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1. Volcanic crisis management supported by near real-time lava flow hazard assessment at Piton de la Fournaise, La Réunion

Author: Magdalena Oryaëlle Chevrel, Andrew Harris, Aline Peltier, Nicolas Villeneuve, Diego Coppola, Mathieu Gouhier, and Stéphane Drenne
Subjects: risk mitigation, effusive eruption, communication tool, civil protection, hazard map, modeling, Geology, QE1-996.5
Abstract: Since 1979, Piton de la Fournaise (La Réunion) has erupted on average two times per year, with 95 % of these eruptions occurring within an uninhabited caldera. However, lava flows have occasionally impacted populated regions on the island, as in 1977 and 1986. Since 2014, an integrated satellite data–driven multinational response to effusive crises has been developed to rapidly assess lava inundation area and flow runout distance. In 2018, this protocol was implemented as a standalone software to provide a lava flow hazard map showing the probability of flow coverage and runouts as a function of discharge rate. Since 2019, the produced short-term hazard map is shared with local civil protection in the first few hours following the start of an eruption to aid in mitigation actions. Multiple exchanges between scientists, the observatory, and civil protection has improved the delivered hazard map, ensuring a common understanding, a product which is of use and usable, and helping to build effective mitigation strategies at Piton de la Fournaise. In this work we illustrate this effective near real-time protocol with case studies and document how the produced short-term hazard map has been tailored to meet the needs of civil protection.
Published: 2022
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2. New Insights Into the Relationship Between Mass Eruption Rate and Volcanic Column Height Based On the IVESPA Data Set

Author: Thomas J. Aubry, Samantha L. Engwell, Costanza Bonadonna, Larry G. Mastin, Guillaume Carazzo, Alexa R. VanEaton, David E. Jessop, Roy G. Grainger, Simona Scollo, Isabelle A. Taylor, A. Mark Jellinek, Anja Schmidt, Sébastien Biass, and Mathieu Gouhier
Subjects: explosive eruption, column height, mass eruption rate, scaling model, eruption intensity, atmospheric conditions, Geophysics. Cosmic physics, QC801-809
Abstract: Abstract Rapid and simple estimation of the mass eruption rate (MER) from column height is essential for real‐time volcanic hazard management and reconstruction of past explosive eruptions. Using 134 eruptive events from the new Independent Volcanic Eruption Source Parameter Archive (IVESPA, v1.0), we explore empirical MER‐height relationships for four measures of column height: spreading level, sulfur dioxide height, and top height from direct observations and as reconstructed from deposits. These relationships show significant differences and highlight limitations of empirical models currently used in operational and research applications. The roles of atmospheric stratification, wind, and humidity remain challenging to detect across the wide range of eruptive conditions spanned in IVESPA, ultimately resulting in empirical relationships outperforming analytical models that account for atmospheric conditions. This finding highlights challenges in constraining the MER‐height relation using heterogeneous observations and empirical models, which reinforces the need for improved eruption source parameter data sets and physics‐based models.
Published: 2023
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3. CNES-ESA satellite contribution to the operational monitoring of volcanic activity: The 2021 Icelandic eruption of Mt. Fagradalsfjall

Author: Mathieu Gouhier, Virginie Pinel, Joaquín M. C. Belart, Marcello De Michele, Catherine Proy, Claire Tinel, Etienne Berthier, Yannick Guéhenneux, Magnus Tumi Gudmundsson, Birgir V. Óskarsson, Shan Gremion, Daniel Raucoules, Sébastien Valade, Francesco Massimetti, and Bjorn Oddsson
Subjects: Volcanology, Remote sensing, Pléiades images, Infrared monitoring, Lava, Environmental protection, TD169-171.8, Disasters and engineering, TA495
Abstract: Abstract Within the framework of the CIEST2 (Cellule d'Intervention d'Expertise Scientifique et Technique new generation) and thanks to the support of CNES, the French space agency, the first phase of the Fagradalsfjall eruption was exceptionally well covered by high resolution optical satellite data, through daily acquisitions of Pléiades images in stereo mode. In this study, we show how Pléiades data provided real-time information useful for the operational monitoring of the ongoing eruption. An estimation of the volume of lava emitted as well as the corresponding effusion rate could be derived and delivered to the civil protection less than 6 h after the data acquisition. This information is complementary to and consistent with estimates obtained through the HOTVOLC service using SEVIRI (Spinning Enhanced Visible and Infrared Imager) sensor on-board Meteosat Second Generation (MGS) geostationary satellites, operated by the European Space Agency (ESA), characterized by a lower spatial resolution and a higher temporal one. In addition to the information provided on the lava emission, Pléiades data also helped characterize the intensity of the eruption by providing insight into the elevation and the velocity of the volcanic plume. The survey of this effusive eruption, well anticipated by a series of precursors, is a proof of concept of the efficiency of optical/thermal satellite data for volcanic crisis real-time monitoring.
Published: 2022
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4. SO2 and tephra emissions during the December 22, 2018 Anak Krakatau eruption

Author: Mathieu Gouhier and Raphaël Paris
Subjects: SO2 degassing, Volcanic ash, Flank Collapse, Anak Krakatau, Geology, QE1-996.5
Abstract: On December 22, 2018 the south-western flank of Anak Krakatau collapsed into the sea, removing 93.8 × 106 m3 of subaerial lavas, and generated a tsunami. Synchronously with the collapse, a large volcanic plume of SO2 and ash (14–15 km in height) has formed, marking the onset of a paroxysmal eruption lasting from December 22, 2018 to January 06, 2019. From remote sensing analysis, we show that the eruption can be divided into three main phases. Phase I and II show both tephra and gas emissions while phase III is mostly degassing. The total amount of SO2 injected in the atmosphere is 173±52 kt, while the minimum bulk magma volume emplaced, estimated from a topographic reconstruction, is ∼45 × 106 m3. This value compares well with a petrologic-based estimate of 56.4 × 106 m3, making the existence of external sulphur sources and sinks quite unlikely. The ice-rich ash plume formation shows that a strong sea-water/magma interaction was responsible for the phreatomagmatic activity throughout the eruption. However, we distinguish a first Vulcanian blast-derived eruption (lasting 40 min) just after the collapse having a Mass Eruption Rate (MER) of 9 × 105 kgs−1, followed by a sustained lower-intensity eruption resulting in ash emissions over hours (MER = 5 × 105 kgs−1). From December 23, daytime photos show typical Surtseyan activity.
Published: 2019
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5. Particle Sedimentation in Numerical Modelling: A Case Study from the Puyehue-Cordón Caulle 2011 Eruption with the PLUME-MoM/HYSPLIT Models

Author: Alessandro Tadini, Mathieu Gouhier, Franck Donnadieu, Mattia de’ Michieli Vitturi, and Federica Pardini
Subjects: tephra fallout, numerical modelling, PLUME-MoM, HYSPLIT, Meteorology. Climatology, QC851-999
Abstract: Numerical modelling of tephra fallout is a fast-developing research area in volcanology. Several models are currently available both to forecast the dispersion of volcanic particles in the atmosphere and to calculate the particles deposited at different locations on the ground. Data from these simulations can then be used both to manage volcanic crises (e.g., protect air traffic) or perform long-term hazard assessment studies (e.g., through hazard maps). Given the importance of these tasks, it is important that each model is thoroughly tested in order to assess advantages and limitations, and to provide useful information for quantifying the model uncertainty. In this study we tested the coupled PLUME-MoM/HYSPLIT models by applying them to the Puyehue–Cordon Caulle 2011 sub-Plinian eruption. More specifically, we tested new features recently introduced in these well-established models (ash aggregation, external water addition, and settling velocity models), we implemented a new inversion procedure, and we performed a parametric analysis. Our main results reaffirm the pivotal role played by mass eruption rate on the final deposit and show that some choices for the input parameters of the model can lead to the large overestimation in total deposited mass (which can be reduced with our inversion procedure). The parametric analysis suggests a most likely value of the mass eruption rate in the range 2.0–6.3 × 106 kg/s. More studies with a similar approach would be advisable in order to provide final users with useful indications about the parameters that should be carefully evaluated before being used as input for this kind of model.
Published: 2022
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6. Evidences of Plug Pressurization Enhancing Magma Fragmentation During the September 2016 Basaltic Eruption at Piton de la Fournaise (La Réunion Island, France)

Author: Simon Thivet, Lucia Gurioli, Andrea Di Muro, Allan Derrien, Valérie Ferrazzini, Mathieu Gouhier, Diego Coppola, Bo Galle, and Santiago Arellano
Subjects: ash, basaltic, fragmentation, Hawaiian‐style activity, Piton de la Fournaise, transient explosions, Geophysics. Cosmic physics, QC801-809, Geology, QE1-996.5
Abstract: Abstract In September 2016, Piton de la Fournaise volcano, well known for its effusive and Hawaiian fountaining activity, produced, at the end of the eruption, an unusual phase of pulsating ash and bomb emission. Integration of geophysical data, with textural and petrological analysis of the samples, allowed us to constrain the main factors that controlled this sudden shift in activity, potentially dangerous for the tourist population that usually approach these “gentle” eruptive sites. Volcanic tremor, lava discharge rates, fountain heights, and SO2 emission changed rapidly during the eruption. Grain size and componentry of the tephra beds evolved from unimodal all along the sequence to bimodal on the last day of the activity, reflecting the contribution of both Hawaiian fountaining at the main vent (Vent A) and transient explosive activity at the second vent (Vent B). Hawaiian fountaining produced highly vesicular and almost microlite‐free tephra (golden pumice and fluidal scoria) while transient explosive activity emitted denser and crystal‐rich tephra (sideromelane and tachylite scoria) sometimes mingled with vesicular fragments. Permeability measurements on lapilli and bomb‐sized samples reveal that golden pumice and fluidal scoria were more gas‐permeable than the sideromelane and tachylite ones, while textural and chemical analyses of the ash support the hypothesis that these sideromelane and tachylite components were inherited from the subsurface crystallization of the initial golden pumice and fluidal scoria components. We thus suggest that Vent B accumulated a plug of degassed, cooled, and low‐permeable magma, which modulated overpressure pulses under the late input of ascending magma.
Published: 2020
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7. The Effect of Using a New Parameterization of Nucleation in the WRF-Chem Model on New Particle Formation in a Passive Volcanic Plume

Author: Somayeh Arghavani, Clémence Rose, Sandra Banson, Aurelia Lupascu, Mathieu Gouhier, Karine Sellegri, and Céline Planche
Subjects: new particle formation, nucleation, CCN, volcanic passive plume, Mount Etna, WRF-Chem, Meteorology. Climatology, QC851-999
Abstract: We investigated the role of the passive volcanic plume of Mount Etna (Italy) in the formation of new particles in the size range of 2.5–10 nm through the gas-to-particle nucleation of sulfuric acid (H2SO4) precursors, formed from the oxidation of SO2, and their evolution to particles with diameters larger than 100 nm. Two simulations were performed using the Weather Research and Forecasting Model coupled with chemistry (WRF-Chem) under the same configuration, except for the nucleation parameterization implemented in the model: the activation nucleation parameterization (JS1 = 2.0 × 10−6 × (H2SO4)) in the first simulation (S1) and a new parameterization for nucleation (NPN) (JS2 = 1.844 × 10−8 × (H2SO4)1.12) in the second simulation (S2). The comparison of the numerical results with the observations shows that, on average, NPN improves the performance of the model in the prediction of the H2SO4 concentrations, newly-formed particles (~2.5–10 nm), and their growth into larger particles (10–100 nm) by decreasing the rates of H2SO4 consumption and nucleation relative to S1. In addition, particles formed in the plume do not grow into cloud condensation nuclei (CCN) sizes (100–215 nm) within a few hours of the vent (tens of km). However, tracking the size evolution of simulated particles along the passive plume indicates the downwind formation of particles larger than 100 nm more than 100 km far from the vent with relatively high concentrations relative to the background (more than 1500 cm−3) in S2. These particles, originating in the volcanic source, could affect the chemical and microphysical properties of clouds and exert regional climatic effects over time.
Published: 2021
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8. A Spectra Classification Methodology of Hyperspectral Infrared Images for Near Real-Time Estimation of the SO2 Emission Flux from Mount Etna with LARA Radiative Transfer Retrieval Model

Author: Charlotte Segonne, Nathalie Huret, Sébastien Payan, Mathieu Gouhier, and Valéry Catoire
Subjects: volcanic plume, SO2 emission flux, passive degassing, remote sensing, spectra image classification, hyperspectral, Science
Abstract: Fast and accurate quantification of gas fluxes emitted by volcanoes is essential for the risk mitigation of explosive eruption, and for the fundamental understanding of shallow eruptive processes. Sulphur dioxide (SO2), in particular, is a reliable indicator to predict upcoming eruptions, and its systemic characterization allows the rapid assessment of sudden changes in eruptive dynamics. In this regard, infrared (IR) hyperspectral imaging is a promising new technology for accurately measure SO2 fluxes day and night at a frame rate down to 1 image per second. The thermal infrared region is not very sensitive to particle scattering, which is an asset for the study of volcanic plume. A ground based infrared hyperspectral imager was deployed during the IMAGETNA campaign in 2015 and provided high spectral resolution images of the Mount Etna (Sicily, Italy) plume from the North East Crater (NEC), mainly. The LongWave InfraRed (LWIR) hyperspectral imager, hereafter name Hyper-Cam, ranges between 850–1300 cm−1 (7.7–11.8 µm). The LATMOS (Laboratoire Atmosphères Milieux Observations Spatiales) Atmospheric Retrieval Algorithm (LARA), which is used to retrieve the slant column densities (SCD) of SO2, is a robust and a complete radiative transfer model, well adapted to the inversion of ground-based remote measurements. However, the calculation time to process the raw data and retrieve the infrared spectra, which is about seven days for the retrieval of one image of SO2 SCD, remains too high to infer near real-time (NRT) SO2 emission fluxes. A spectral image classification methodology based on two parameters extracting spectral features in the O3 and SO2 emission bands was developed to create a library. The relevance is evaluated in detail through tests. From data acquisition to the generation of SO2 SCD images, this method requires only ~40 s per image, which opens the possibility to infer NRT estimation of SO2 emission fluxes from IR hyperspectral imager measurements.
Published: 2020
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9. Operational Response to Volcanic Ash Risks Using HOTVOLC Satellite-Based System and MOCAGE-Accident Model at the Toulouse VAAC

Author: Mathieu Gouhier, Mathieu Deslandes, Yannick Guéhenneux, Philippe Hereil, Philippe Cacault, and Béatrice Josse
Subjects: ash cloud, volcano, VAAC, satellite, HOTVOLC, risk, Meteorology. Climatology, QC851-999
Abstract: In 2010, the Eyjafjallajökull volcano erupted, generating an ash cloud causing unprecedented disruption of European airspace. Despite an exceptional situation, both the London and Toulouse Volcanic Ash Advisory Centres (VAAC) provided critical information on the location of the cloud and on the concentration of ash, thus contributing to the crisis management. Since then, substantial efforts have been carried out by the scientific community in order to improve remote sensing techniques and numerical modeling. Satellite instruments have proven to be particularly relevant for the characterization of ash cloud properties and a great help in the operational management of volcanic risk. In this study, we present the satellite-based system HOTVOLC developed at the Observatoire de Physique du Globe de Clermont-Ferrand (OPGC) using Meteosat geostationary satellite and designed for real-time monitoring of active volcanoes. After a brief presentation of the system we provide details on newly developed satellite products dedicated to the ash cloud characterization. This includes, in particular, ash cloud altitude and vertical column densities (VCD). Then, from the Stromboli 2018 paroxysm, we show how HOTVOLC can be used in a timely manner to assist the Toulouse VAAC in the operational management of the eruptive crisis. In the second part of the study, we provide parametric tests of the MOCAGE-Accident model run by the Toulouse VAAC from the April 17 Eyjafjallajökull eruption. For this purpose, we tested a range of eruption source parameters including the Total Grain Size Distribution (TGSD), the eruptive column profile, the top plume height and mass eruption rate (MER), as well as the fine ash partitioning. Finally, we make a comparison on this case study between HOTVOLC and MOCAGE-Accident VCD.
Published: 2020
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10. Reconstruction of the 2014-2015 FOGO Volcano (Cape Verde) Eruption Through Thermal Remotely Sensed Imagery.

Author: Vasco Miranda, Pedro Pina, Sandra Heleno, Mathieu Gouhier, and Stéphanie Dumont
Published: 2019
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11. HOTVOLC: The official French satellite-based service for operational monitoring and early warning of volcanic ash plumes

Author: Guéhenneux, Yannick, primary and Mathieu, Gouhier, additional
Published: 2023
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12. New insights into the relationship between mass eruption rate and volcanic column height based on the IVESPA dataset

Author: Thomas Jacques Aubry, Samantha L Engwell, Costanza Bonadonna, Larry Garver Mastin, Guillaume Carazzo, Alexa Van Eaton, David Jessop, Roy Gordon Grainger, Simona Scollo, Isabelle Alice Taylor, Mark Jellinek, Anja Schmidt, Sébastien Biass, Mathieu Gouhier, Université de Genève = University of Geneva (UNIGE), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania (INGV), Istituto Nazionale di Geofisica e Vulcanologia, and University of Cambridge [UK] (CAM)
Subjects: [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology
Abstract: Relating the mass eruption rate (MER) of explosive eruptions to column height in the atmosphere is key to reconstructing past eruptions and forecasting volcanic hazards. Using 134 eruptive events from the Independent Volcanic Eruption Source Parameter Archive (IVESPA v1.0), we explore the canonical MER-height relationship for four measures of column height: spreading level, sulfur dioxide height, and top height from both directly observed plumes and those reconstructed from deposits. These relationships show significant differences and should be chosen carefully for operational and research applications. The roles of atmospheric stratification, wind, and humidity remain challenging to assess across the large range of eruptive conditions in this database, ultimately resulting in empirical relationships outperforming analytical models that account for atmospheric conditions. This finding reveals the complexity of the height-MER relation that is difficult to constrain based on available heterogeneous observations, which reinforces the need for improved datasets to develop eruptive column models.
Published: 2023

13. Surveillance des volcans par télédétection spatiale

Author: Mathieu GOUHIER
Abstract: Depuis les années 1980, l’avènement des techniques de télédétection spatiales a permis une amélioration notable de la détection et du suivi des éruptions volcaniques. C'est un domaine en fort évolution, avec le développement de nouveaux capteurs et l'amélioration des résolutions spectrales et spatiales ainsi que temporelles. On utilise soit des capteurs passifs (visible, UV et IR), soit des capteurs actifs (radar, lidar). On surveille les anomalies thermiques, les écoulements, les panaches de cendres et certains gaz. Ce chapitre décrit à la fois les principes des méthodes et leurs applications à la surveillance opérationnelle.
Published: 2022
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14. Tephra Fallout Probabilistic Hazard Maps for Cotopaxi and Guagua Pichincha Volcanoes (Ecuador) With Uncertainty Quantification

Author: Andrea Bevilacqua, Benjamin Bernard, Arnaud Guillin, Silvana Hidalgo, Olivier Roche, Mathieu Gouhier, Alessandro Tadini, Nourddine Azzaoui, Pablo Samaniego, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Laboratoire de Mathématiques Blaise Pascal (LMBP), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Instituto Geofísico, Escuela Politécnica Nacional, Escuela Politécnica Nacional (EPN), Istituto Nazionale di Geofisica e Vulcanologia – Sezione di Pisa (INGV), Istituto Nazionale di Geofisica e Vulcanologia, ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), and ANR-16-IDEX-0001,CAP 20-25,CAP 20-25(2016)
Subjects: geography, geography.geographical_feature_category, Cotopaxi, uncertainty quantification, Probabilistic logic, Numerical models, Hazard analysis, Hazard, Tephra fallout, Guagua Pichincha, Geophysics, Volcano, Space and Planetary Science, Geochemistry and Petrology, volcanic hazard assessment, Earth and Planetary Sciences (miscellaneous), [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Environmental science, Physical geography, Uncertainty quantification, Tephra
Abstract: co-auteur étranger; International audience; Tephra fallout hazard assessment is undertaken with probabilistic maps that rely on numerical models. Regarding maps production, the input parameters of the model (including atmospheric conditions), the physical approximations of the numerical simulations, and the probabilities of occurrence of different eruption types in specific time frames are among the most critical sources of uncertainty. We therefore present a tephra fallout hazard assessment study for two active volcanoes (Cotopaxi and Guagua Pichincha) in Ecuador. We utilize PLUME-MoM/HYSPLIT models, and a procedure for uncertainty quantification where: i) the uncertainty on eruptive source parameters and eruption type occurrence is quantified through expert elicitation; ii) we implement a new procedure for correlations between the different parameters, and iii) we use correction coeffients to take into account the uncertainty of the numerical model. Maps of exceedance probability given a deposit thickness threshold, and thickness maps given a robability of exceedence, are produced 1) for two eruptive scenarios (sub-plinian and Plinian) and 2) as a combination of these scenarios in case the next eruption will be sub-Plinian or Plinian. These maps are described according to the uncertainty distribution of eruption type occurrence probabilities, considering their 5th percentile, mean, and 95th percentile values. We finally present hazard curves describing exceeding probabilities in 10 sensitive sites within the city of Quito. Additional information includes the areal extent and the population potentially affected by different isolines of tephra accumulation. This work indicates that full uncertainty quantification helps in providing more robust scientific information, improving the hazard assessment reliability.
Published: 2022
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15. The Effect of Using a New Parameterization of Nucleation in the WRF-Chem Model on New Particle Formation in a Passive Volcanic Plume

Author: Somayeh Arghavani, Clémence Rose, Sandra Banson, Aurelia Lupascu, Mathieu Gouhier, Karine Sellegri, Céline Planche, Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Institute for Advanced Sustainability Studies [Potsdam] (IASS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, CCN, Atmospheric Science, 010504 meteorology & atmospheric sciences, nucleation, new particle formation, volcanic passive plume, Mount Etna, WRF-Chem, Environmental Science (miscellaneous), 010502 geochemistry & geophysics, 01 natural sciences, 13. Climate action, Meteorology. Climatology, QC851-999, 0105 earth and related environmental sciences
Abstract: We investigated the role of the passive volcanic plume of Mount Etna (Italy) in the formation of new particles in the size range of 2.5–10 nm through the gas-to-particle nucleation of sulfuric acid (H2SO4) precursors, formed from the oxidation of SO2, and their evolution to particles with diameters larger than 100 nm. Two simulations were performed using the Weather Research and Forecasting Model coupled with chemistry (WRF-Chem) under the same configuration, except for the nucleation parameterization implemented in the model: the activation nucleation parameterization (JS1 = 2.0 × 10−6 × (H2SO4)) in the first simulation (S1) and a new parameterization for nucleation (NPN) (JS2 = 1.844 × 10−8 × (H2SO4)1.12) in the second simulation (S2). The comparison of the numerical results with the observations shows that, on average, NPN improves the performance of the model in the prediction of the H2SO4 concentrations, newly-formed particles (~2.5–10 nm), and their growth into larger particles (10–100 nm) by decreasing the rates of H2SO4 consumption and nucleation relative to S1. In addition, particles formed in the plume do not grow into cloud condensation nuclei (CCN) sizes (100–215 nm) within a few hours of the vent (tens of km). However, tracking the size evolution of simulated particles along the passive plume indicates the downwind formation of particles larger than 100 nm more than 100 km far from the vent with relatively high concentrations relative to the background (more than 1500 cm−3) in S2. These particles, originating in the volcanic source, could affect the chemical and microphysical properties of clouds and exert regional climatic effects over time.
Published: 2022
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16. Evidence of New Particle Formation Within Etna and Stromboli Volcanic Plumes and Its Parameterization From Airborne In Situ Measurements

Author: Jonathan Duplissy, Maher Sahyoun, T. Bourianne, Mathieu Gouhier, Chao Yan, Markku Kulmala, Alfons Schwarzenboeck, Régis Dupuy, Céline Planche, John B. Nowak, Karine Sellegri, Tuukka Petäjä, Joel Brito, Evelyn Freney, Aurélie Colomb, Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Helsinki Institute of Physics (HIP), Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), NASA Langley Research Center [Hampton] (LaRC), ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), ANR-16-IDEX-0001,CAP 20-25,CAP 20-25(2016), Institute for Atmospheric and Earth System Research (INAR), INAR Physics, Polar and arctic atmospheric research (PANDA), University of Helsinki, Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Particle number, volcanic secondary aerosols, 116 Chemical sciences, Mesoscale meteorology, ASH, Atmospheric sciences, 114 Physical sciences, 01 natural sciences, CLOUD CONDENSATION NUCLEI, Troposphere, chemistry.chemical_compound, SULFURIC-ACID, ATMOSPHERIC NUCLEATION, new particle formation, CHEMISTRY, aerosol formation rate parameterization, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Earth and Planetary Sciences (miscellaneous), Cloud condensation nuclei, EMISSIONS, Sulfur dioxide, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, sulfuric acid, volcanic plume, AEROSOL, KILAUEA VOLCANO, Aerosol, Boundary layer, Geophysics, chemistry, Volcano, GAS, 13. Climate action, Space and Planetary Science, GROWTH, Etna and Stromboli
Abstract: Co-auteur étranger; International audience; Volcanic emissions can significantly affect the Earth's radiation budget by emitting aerosol particles and gas‐phase species that can result in the new particle formation (NPF). These particles can scatter solar radiation or modify cloud properties, with consequences on health, weather, and climate. To our knowledge, this is the first dedicated study detailing how gas‐phase precursors emitted from volcanic plumes can influence the NPF. A series of airborne measurements were performed around the Etna and Stromboli volcanoes within the framework of the CLerVolc and STRAP projects. The ATR‐42 aircraft was equipped with a range of instrumentation allowing the measurement of particle number concentration in diameter range above 2.5 nm, and gaseous species to investigate the aerosol dynamics and the processes governing the NPF and their growth within the volcanic plumes. We demonstrate that NPF occurs within the volcanic plumes in the Free Troposphere (FT) and Boundary Layer (BL). Typically, the NPF events were more pronounced in the FT, where the condensational sink was up to two orders of magnitude smaller and the temperature was ~20°C lower than in the BL. Within the passive volcanic plume, the concentration of sulfur dioxide, sulfuric acid, and N2.5 were as high as 92 ppbV, 5.65×108 and 2.4×105 cm–3, respectively. Using these measurements, we propose a new parameterization for NPF rate (J2.5) within the passive volcanic plume in the FT. These results can be incorporated into mesoscale models to better assess the impact of the particle formed by natural processes, i.e. volcanic plumes, on climate.
Published: 2019
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17. The buried caldera boundary of the Vesuvius 1631 eruption revealed by present-day soil CO2 concentration

Author: Alexis Shakas, Giovanni Orsi, G. P. Ricciardi, M. A. Di Vito, Anthony Finizola, Niklas Linde, Stéphanie Barde-Cabusson, Guillaume Levieux, Ludovic Baron, G. Mauri, Francesco Sortino, X. Guichet, Julie Morin, Riccardo Vassallo, Mathieu Gouhier, Tullio Ricci, Emilie Roulleau, Matthieu Poret, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Laboratoire GéoSciences Réunion (LGSR), Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Napoli (INGV), Applied and Environmental Geophysics Group, Institute of Earth Sciences [Lausanne], Université de Lausanne = University of Lausanne (UNIL)-Université de Lausanne = University of Lausanne (UNIL), Centre for Hydrogeology and Geothermics [Switzerland], Université de Neuchâtel (UNINE), IFP Energies nouvelles (IFPEN), Ministère de l'environnement, Ministère de l'Environnement, Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Palermo (INGV), Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), University of Naples Federico II = Università degli studi di Napoli Federico II, European Project: 308665,EC:FP7:ENV,FP7-ENV-2012-two-stage,MED-SUV(2013), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université de La Réunion (UR)-Institut de Physique du Globe de Paris, Université de Lausanne (UNIL)-Université de Lausanne (UNIL), and Università degli studi di Napoli Federico II
Subjects: geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Anomaly (natural sciences), [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Pyroclastic rock, Present day, 010502 geochemistry & geophysics, 01 natural sciences, Hydrothermal circulation, Geophysics, Impact crater, Volcano, 13. Climate action, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Caldera, Petrology, Tephra, Geology, 0105 earth and related environmental sciences
Abstract: International audience; Volcanic risk at Vesuvius is one of the highest in the world due to the ~670,000 inhabitants living in the Red Zone, the area exposed to both pyroclastic flows and tephra fallout, to be evacuated before renewal of any eruptive activity. The national emergency plan for Vesuvius builds its risk zonation on a scenario similar to the last sub-Plinian eruption, which occurred in 1631. This study aims at providing new insights on the geometry of the caldera associated with this historical eruption. The impact of past Vesuvius eruptions on present-day soil CO2 concentration has been investigated by means of an extended geochemical survey carried out for identifying the circulation pathways of hydrothermal fluids inside the volcano. We performed 4018 soil CO2 concentration measurements over the whole Somma-Vesuvius volcanic complex, covering an area of 50 km2. Besides relatively low values, the results show a significant spatial CO2 concentration heterogeneity over Somma-Vesuvius ranging from the atmospheric value (~400 ppm) up to ~24,140 ppm. The summit of Vesuvius shows an area with anomalous CO2 concentrations well matching the crater rim of the 1906 eruption. Along the cone flanks, secondary CO2 anomalies highlight a roughly circular preferential pathway detected along 8 radial profiles at distances between ~840 m and ~1150 m from the bottom of the present-day crater resulting from the last eruption in 1944. In depth review of the available literature highlights an agreement between this circle-like shaped anomaly and the 1631 sub-Plinian eruption caldera boundary. Indeed, based on the historical chronicles the depression produced by the 1631 eruption had a diameter of 1686 m, whereas the CO2 circular anomaly indicates a diameter of 1956 m. Finally, the results were compared with a 3-D density model obtained from a recent gravity survey that corroborates both the literature and the CO2 data in terms of potential buried structure at the base of the Vesuvius cone.
Published: 2019
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18. Eruption type probability and eruption source parameters at Cotopaxi and Guagua Pichincha volcanoes (Ecuador) with uncertainty quantification

Author: Andrea Bevilacqua, Silvana Hidalgo, Antonio Proaño, Nourddine Azzaoui, Hugo Yepes, Pablo Samaniego, Benjamin Bernard, Olivier Roche, Mia Pique, Augusto Neri, Elizabeth Gaunt, Alessandro Tadini, Willy Aspinall, Mattia de' Michieli Vitturi, Marjorie Encalada, Arnaud Guillin, Raffaello Cioni, Julia Eychenne, Marco Pistolesi, Mathieu Gouhier, Silvia Vallejo, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Instituto Geofísico, Escuela Politécnica Nacional, Laboratoire de Mathématiques Blaise Pascal (LMBP), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Istituto Nazionale di Geofisica e Vulcanologia – Sezione di Pisa (INGV), Istituto Nazionale di Geofisica e Vulcanologia, School of Earth Sciences [Bristol], University of Bristol [Bristol], Dipartimento di Scienze della Terra [Firenze] (DST), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Dipartimento di Scienze della Terra [Pisa], University of Pisa - Università di Pisa, School of Earth and Environmental Sciences, University of Queensland, University of Queensland [Brisbane], ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), ANR-16-IDEX-0001,CAP 20-25,CAP 20-25(2016), and Università degli Studi di Firenze = University of Florence (UniFI)
Subjects: Volcanic hazards, 010504 meteorology & atmospheric sciences, 010502 geochemistry & geophysics, 01 natural sciences, Geochemistry and Petrology, Joint probability distribution, Rhyolite, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Tephra, Uncertainty quantification, 0105 earth and related environmental sciences, Event (probability theory), Guagua Pichincha volcano, geography, geography.geographical_feature_category, Andesite, Cotopaxi volcano, Expert elicitation, Volcanic hazard, Scoring methods, Elicitation, Volcano, 13. Climate action, Seismology, Geology
Abstract: Co-auteur étranger; International audience; Future occurrence of explosive eruptive activity at Cotopaxi and Guagua Pichincha volcanoes, Ecuador, is assessed probabilistically, utilizing expert elicitation. Eight eruption types were considered for each volcano. Type event probabilities were evaluated for the next eruption at each volcano and for at least one of each type within the next 100 years. For each type, we elicited relevant eruption source parameters (duration, average plume height, and total tephra mass). We investigated the robustness of these elicited evaluations by deriving probability uncertainties using three expert scoring methods. For Cotopaxi, we considered both rhyolitic and andesitic magmas. Elicitation findings indicate that the most probable next eruption type is an andesitic hydrovolcanic/ash-emission (~ 26–44% median probability), which has also the highest median probability of recurring over the next 100 years. However, for the next eruption at Cotopaxi, the average joint probabilities for sub-Plinian or Plinian type eruption is of order 30–40%—a significant chance of a violent explosive event. It is inferred that any Cotopaxi rhyolitic eruption could involve a longer duration and greater erupted mass than an andesitic event, likely producing a prolonged emergency. For Guagua Pichincha, future eruption types are expected to be andesitic/dacitic, and a vulcanian event is judged most probable for the next eruption (median probability ~40–55%); this type is expected to be most frequent over the next 100 years, too. However, there is a substantial probability (possibly >40% in average) that the next eruption could be sub-Plinian or Plinian, with all that implies for hazard levels.
Published: 2021
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19. A spectra classification methodology of infrared hyperspectral images to reach near real-time SO2 emission flux estimation of Mount Etna plume

Author: Charlotte Segonne, Mathieu Gouhier, Nathalie Huret, Sébastien Payan, Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: geography, geography.geographical_feature_category, Infrared, Longwave, Hyperspectral imaging, Context (language use), Plume, Atmospheric radiative transfer codes, Volcano, 13. Climate action, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Environmental science, Spectral resolution, Remote sensing
Abstract: Monitoring active volcanoes activity passes through the detection of fluctuations in degassing levels which may reflect changes in the magma supply rate and help inform a short-term forecast of on-going eruptions. Infrared hyperspectral imagers, which is an imaging technology still little used for volcanoes monitoring, have been deployed for various field campaigns on active volcanoes recently. For example, the Hyper-Cam LWIR (LongWave InfraRed) ranging between 850-1300 cm-1 (7.7 - 11.8 µm) with a spectral resolution up to 0.25 cm-1, provided high spectral resolution images from ground-based measurements of the Mount Etna (Sicily, Italy) plume during IMAGETNA campaign in June 2015. Processing the raw data and retrieving the infrared spectra with the LATMOS (Laboratoire Atmosphères Milieux Observations Spatiales) Atmospheric Retrieval Algorithm (LARA), a robust and a complete radiative transfer model, require a calculation time of ~7 days per image.One of the main ways of risk mitigation effects of explosive eruptions is to get a fast and accurate quantification of SO2 fluxes emitted by volcanoes. In this context, using the dataset acquired during IMAGETNA campaign at Mount Etna, a spectra classification methodology has been developed to drastically decrease the calculation time and reach near real-time retrievals of SO2 slant column densities. The methodology is based on a network built on two layers of information from the extraction of spectral features in the O3 and SO2 emission bands. A training dataset of five SO2 slant column densities images retrieved with the time-consuming pixel-by-pixel retrieval method allowed the creation of a library. The spectra classification makes it possible to process each hyperspectral image in less than 40 seconds. It opens the possibility to infer near real-time estimation of SO2 emission fluxes from IR hyperspectral imager measurements.
Published: 2021
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20. Response of Fogo volcano (Cape Verde) to lunisolar gravitational forces during the 2014-2015 eruption

Author: Graça Silveira, Jean-Louis Le Mouël, Susana Custódio, Mathieu Gouhier, Yannick Guéhenneux, Fernando Lopes, Stéphanie Dumont, Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)
Subjects: Volcanic hazards, 010504 meteorology & atmospheric sciences, Physics and Astronomy (miscellaneous), Lava, 2014-2015 Fogo eruption, Fogo eruption, Context (language use), Forcing (mathematics), 010502 geochemistry & geophysics, Eruptive activity, 01 natural sciences, Cape verde, Effusive eruption, SSA, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Astronomy and Astrophysics, Geophysics, Volcano, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Magma, Seismic tremor, Earth tides, External forcing, Geology, Seismology
Abstract: International audience; Volcanoes are complex systems that evolve in space and time as a result of their eruptive activity. Volcanic eruptions represent the ultimate expression of a complex interplay between internal and external processes that span across different time scales. Deciphering how internal and external processes interact at the time scale of eruptions may provide key insights on the temporal evolution of eruptions and also help to better evaluate associated volcanic hazards. Studies of the tidal influence on volcanic activity have fallen within this context, although the cause-effect relationship between tides and eruptions is still unclear. In this study, we used Singular Spectrum Analysis to analyze three time-series, namely the seismic tremor, SO2 emission and lava volume flow rate, which cover the first month of effusive activity at Fogo volcano, Cape Verde, in 2014-2015. We detect 9 tidal periodicities and up to 5 in each time-series ranging from semi-diurnal to fortnightly periods. We show that the movement of magma at crustal depths and at surface as well as gas emission during the effusive eruption are all modulated by lunisolar gravitational forces. We highlight the relevance of the volcano location on Earth, which together with the timing of the eruption, associated with a specific astronomical configuration, result in a specific combination of tides that directly influence the volcano eruptive activity. With this data set, we further investigate the response of Fogo volcano to this external forcing. We show that during the 2014-2015 eruption, Fogo volcano acted as a bandpass filter to quasi-permanent tidal oscillations.
Published: 2021
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21. The Independent Volcanic Eruption Source Parameter Archive (IVESPA, version 1.0): A new observational database to support explosive eruptive column model validation and development

Author: David Jessop, Sébastien Biass, Kristi L. Wallace, Simona Scollo, A. Mark Jellinek, Isabelle Taylor, Mathieu Gouhier, Larry G. Mastin, Anja Schmidt, Thomas Aubry, Samantha Engwell, Marcus Bursik, Costanza Bonadonna, Julia Eychenne, Roy G. Grainger, Alexa R. Van Eaton, Guillaume Carazzo, Aubry, Thomas [0000-0002-9275-4293], Schmidt, Anja [0000-0001-8759-2843], Apollo - University of Cambridge Repository, Department of Geography, University of Cambridge, University of Cambridge [UK] (CAM), Sidney Sussex College, British Geological Survey [Edinburgh], British Geological Survey (BGS), Department of Earth Sciences, University of Geneva, University of Geneva [Switzerland], Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania (INGV), Istituto Nazionale di Geofisica e Vulcanologia, U.S. Geological Survey, Cascades Volcano Observatory, COMET, Atmospheric, Oceanic and Planetary Physics, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Observatoire Volcanologique et Sismologique de Guadeloupe (OVSG), Institut de Physique du Globe de Paris, U.S. Geological Survey, Alaska Volcano Observatory, Earth Observatory of Singapore, Nanyang Technological University, Earth Ocean and Atmospheric Sciences, University of British Columbia, Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K, Université de Genève = University of Geneva (UNIGE), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut de Physique du Globe de Paris (IPG Paris), and Nanyang Technological University [Singapour]
Subjects: geography, geography.geographical_feature_category, Vulcanian eruption, Explosive eruption, 010504 meteorology & atmospheric sciences, Pyroclastic rock, 37 Earth Sciences, 3705 Geology, Volcanology, Eruption column, 010502 geochemistry & geophysics, 01 natural sciences, 3703 Geochemistry, Geophysics, Volcano, 13. Climate action, Geochemistry and Petrology, ddc:550, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Range (statistics), Tephra, 3706 Geophysics, Geology, Seismology, 0105 earth and related environmental sciences
Abstract: International audience; Eruptive columnmodels are powerful tools for investigating the transport of volcanic gas and ash, reconstructing past explosive eruptions, and simulating future hazards. However, the evaluation of these models is challenging as it requires independent estimates of themainmodel inputs (e.g.mass eruption rate) and outputs (e.g. column height). There exists no database of independently estimated eruption source parameters (ESPs) that is extensive, standardized, maintained, and consensus-based. This paper introduces the Independent Volcanic Eruption Source Parameter Archive (IVESPA, ivespa.co.uk), a community effort endorsed by the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) Commission on Tephra HazardModelling.We compiled data for 134 explosive eruptive events, spanning the 1902-2016 period, with independent estimates of: i) total erupted mass of fall deposits; ii) duration; iii) eruption column height; and iv) atmospheric conditions. Crucially, we distinguish plume top versus umbrella spreading height, and the height of ash versus sulphur dioxide injection. All parameter values provided have been vetted independently by at least two experts. Uncertainties are quantified systematically, including flags to describe the degree of interpretation of the literature required for each estimate. IVESPA also includes a range of additional parameters such as total grain size distribution,eruption style, morphology of the plume (weak versus strong), and mass contribution from pyroclastic density currents, where available. We discuss the future developments and potential applications of IVESPA and make recommendations for reporting ESPs to maximize their usability across different applications. IVESPA covers an unprecedented range of ESPs and can therefore be used to evaluate and develop eruptive column models across a wide range of conditions using a standardized dataset.
Published: 2021
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22. A Spectra Classification Methodology of Hyperspectral Infrared Images for Near Real-Time Estimation of the SO2 Emission Flux from Mount Etna with LARA Radiative Transfer Retrieval Model

Author: Sébastien Payan, Valéry Catoire, Nathalie Huret, Mathieu Gouhier, Charlotte Segonne, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), CNES/INSU APR 2020, ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), European Project: 730970, Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES)
Subjects: 010504 meteorology & atmospheric sciences, Infrared, Science, [INFO.INFO-DS]Computer Science [cs]/Data Structures and Algorithms [cs.DS], SO2 emission flux, 010502 geochemistry & geophysics, 01 natural sciences, remote sensing, Atmospheric radiative transfer codes, Data acquisition, Radiative transfer, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Spectral resolution, 0105 earth and related environmental sciences, Remote sensing, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], passive degassing, volcanic plume, Longwave, Hyperspectral imaging, Frame rate, spectra image classification, hyperspectral, infrared, General Earth and Planetary Sciences, Environmental science, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing
Abstract: Fast and accurate quantification of gas fluxes emitted by volcanoes is essential for the risk mitigation of explosive eruption, and for the fundamental understanding of shallow eruptive processes. Sulphur dioxide (SO2), in particular, is a reliable indicator to predict upcoming eruptions, and its systemic characterization allows the rapid assessment of sudden changes in eruptive dynamics. In this regard, infrared (IR) hyperspectral imaging is a promising new technology for accurately measure SO2 fluxes day and night at a frame rate down to 1 image per second. The thermal infrared region is not very sensitive to particle scattering, which is an asset for the study of volcanic plume. A ground based infrared hyperspectral imager was deployed during the IMAGETNA campaign in 2015 and provided high spectral resolution images of the Mount Etna (Sicily, Italy) plume from the North East Crater (NEC), mainly. The LongWave InfraRed (LWIR) hyperspectral imager, hereafter name Hyper-Cam, ranges between 850&ndash, 1300 cm&minus, 1 (7.7&ndash, 11.8 &micro, m). The LATMOS (Laboratoire Atmosph&egrave, res Milieux Observations Spatiales) Atmospheric Retrieval Algorithm (LARA), which is used to retrieve the slant column densities (SCD) of SO2, is a robust and a complete radiative transfer model, well adapted to the inversion of ground-based remote measurements. However, the calculation time to process the raw data and retrieve the infrared spectra, which is about seven days for the retrieval of one image of SO2 SCD, remains too high to infer near real-time (NRT) SO2 emission fluxes. A spectral image classification methodology based on two parameters extracting spectral features in the O3 and SO2 emission bands was developed to create a library. The relevance is evaluated in detail through tests. From data acquisition to the generation of SO2 SCD images, this method requires only ~40 s per image, which opens the possibility to infer NRT estimation of SO2 emission fluxes from IR hyperspectral imager measurements.
Published: 2020
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23. Operational Response to Volcanic Ash Risks Using HOTVOLC Satellite-Based System and MOCAGE-Accident Model at the Toulouse VAAC

Author: Yannick Guéhenneux, Mathieu Gouhier, Mathieu Deslandes, Béatrice Josse, Philippe Cacault, and Philippe Hereil
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Plume height, satellite, Cloud computing, Environmental Science (miscellaneous), lcsh:QC851-999, 010502 geochemistry & geophysics, 01 natural sciences, modelling, Altitude, HOTVOLC, 0105 earth and related environmental sciences, risk, geography, geography.geographical_feature_category, business.industry, VAAC, volcano, Volcano, ash cloud, Geostationary orbit, Environmental science, Satellite, lcsh:Meteorology. Climatology, Eruption rate, business, Volcanic ash
Abstract: In 2010, the Eyjafjallaj&ouml, kull volcano erupted, generating an ash cloud causing unprecedented disruption of European airspace. Despite an exceptional situation, both the London and Toulouse Volcanic Ash Advisory Centres (VAAC) provided critical information on the location of the cloud and on the concentration of ash, thus contributing to the crisis management. Since then, substantial efforts have been carried out by the scientific community in order to improve remote sensing techniques and numerical modeling. Satellite instruments have proven to be particularly relevant for the characterization of ash cloud properties and a great help in the operational management of volcanic risk. In this study, we present the satellite-based system HOTVOLC developed at the Observatoire de Physique du Globe de Clermont-Ferrand (OPGC) using Meteosat geostationary satellite and designed for real-time monitoring of active volcanoes. After a brief presentation of the system we provide details on newly developed satellite products dedicated to the ash cloud characterization. This includes, in particular, ash cloud altitude and vertical column densities (VCD). Then, from the Stromboli 2018 paroxysm, we show how HOTVOLC can be used in a timely manner to assist the Toulouse VAAC in the operational management of the eruptive crisis. In the second part of the study, we provide parametric tests of the MOCAGE-Accident model run by the Toulouse VAAC from the April 17 Eyjafjallaj&ouml, kull eruption. For this purpose, we tested a range of eruption source parameters including the Total Grain Size Distribution (TGSD), the eruptive column profile, the top plume height and mass eruption rate (MER), as well as the fine ash partitioning. Finally, we make a comparison on this case study between HOTVOLC and MOCAGE-Accident VCD.
Published: 2020
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24. Modelling new particle formation in a passive volcanic plume using a new parameterisation in WRF-Chem - effects on climate-relevant variables at the regional scale

Author: Céline Planche, Sandra Banson, Clémence Rose, Mathieu Gouhier, Karine Sellegri, and Aurelia Lupascu
Subjects: Scale (ratio), Volcanic plume, Weather Research and Forecasting Model, Environmental science, Particle, Atmospheric sciences
Abstract: New particle formation (NPF) is an important source of aerosol particles at global scale, including, in particular, cloud condensation nuclei (CCN). NPF has been observed worldwide in a broad variety of environments, but some speciﬁc conditions, such as those encountered in volcanic plumes, remain poorly documented in the literature. Yet, these conditions could promote the occurrence of the process, as recently evidenced in the volcanic eruption plume of the Piton de la Fournaise (Rose at al. 2019); a dominant fraction of the volcanic particles was moreover found to be of secondary origin in the plume, further highlighting the importance of the particle formation and growth processes associated to the volcanic plume eruption. A deeper comprehension of such natural processes is thus essential to assess their climate-related effects at present days but also to better deﬁne pre-industrial conditions and their variability in climate model simulations.Sulfuric acid (SA) is commonly accepted as one of the main precursors for atmospheric NPF, and its role could be even more important in volcanic plume conditions, as recently evidenced by the airborne measurements conducted in the passive volcanic plumes of Etna and Stromboli (Sahyoun et al., 2019). Indeed, the flights performed in the frame of the STRAP campaign have allowed direct measurement of SA in such conditions for the first time, and have highlighted a strong connection between the cluster formation rate and SA concentration. Following these observations, the objective of the present work was to further quantify the formation of new particles in a volcanic plume and assess the effects of the process at a regional scale. For that purpose, the new parameterisation of nucleation derived by Sahyoun et al. (2019) was introduced in the model WRF-Chem, further optimized for the description of NPF. The flight ETNA13 described in detail in Sahyoun et al. (2019) was used as a case study to evaluate the effect of the new parameterisation on the cluster formation rate and particle number concentration in various size ranges, including CCN (i.e. climate-relevant) sizes.References: Sahyoun, M., Freney, E., Brito, J., Duplissy, J., Gouhier, M., Colomb, A., Dupuy, R., Bourianne, T., Nowak, J. B., Yan, C., Petäjä, T., Kulmala, M., Schwarzenboeck, A., Planche, C., and Sellegri, K.: Evidence of new particle formation within Etna and Stromboli volcanic plumes and its parameterization from airborne in-situ measurements, J. Geophys. Res.-Atmos., 124, 5650–5668, https://doi.org/10.1029/2018JD028882, 2019.Rose, C., Foucart, B., Picard, D., Colomb, A., Metzger, J.-M., Tulet, P., and Sellegri, K.: New particle formation in the volcanic eruption plume of the Piton de la Fournaise: specific features from a long-term dataset, Atmos. Chem. Phys., 19, 13243–13265, https://doi.org/10.5194/acp-19-13243-2019, 2019.
Published: 2020
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25. A new database of independently estimated eruption source parameters devoted to eruptive column model evaluation

Author: Samantha Engwell, Thomas Aubry, Sebastien Biass, Costanza Bonadonna, Marcus Bursik, Guillaume Carazzo, Julia Eychenne, Mathieu Gouhier, Don Grainger, Mark Jellinek, David Jessop, Larry Mastin, David Pyle, Simona Scollo, Isabelle Taylor, Alexa Van Eaton, Kristi Wallace, and Mark Woodhouse
Abstract: Eruptive column models are crucial for managing volcanic crises, forecasting future events, and reconstructing past eruptions. Given their central role in volcanology and the large uncertainties weakening their predictions, the evaluation and improvement of these models is critical. Such evaluation is challenging as it requires independent estimates of the main model inputs (e.g. mass eruption rate) and outputs (e.g. column height). Despite recent efforts to extend datasets of independently estimated eruption source parameters (ESP) (e.g. Mastin 2014, Aubry et al. 2017), there is no standardized, maintained, and community-based ESP database devoted to the evaluation of eruptive column models.Here we present a new ESP database designed to respond to the needs of the plume modelling community, and which will also be valuable to observatories, field volcanologists, and volcanic ash advisory centers. We compiled data for over 130 eruptive events with independent estimates of: i) the mass eruption rate; ii) the height reached by the column; and iii) atmospheric conditions during the eruption. In contrast with previous ESP datasets, we distinguish estimates of column height that relate to different phases (ash and SO2) and parts of the column (plume top or umbrella). We additionally provide the total grain size distribution, uncertainties in eruption parameters, and multiple sources for atmospheric profiles for events where these parameters are available. The database also includes a wealth of additional information which will enable modelers to distinguish between different eruptions when evaluating or calibrating models. This includes the type of eruption, the morphology of the plume (weak/transitional/strong), and the occurrence and mass entrained within pyroclastic density currents.We will apply the new database to revisit empirical scaling relationships between the mass eruption rate and “plume height”. In particular, we will show how such relationships depend on the type of height (e.g. SO2 height vs. ash top height) and eruption (e.g. magmatic vs. phreatomagmatic) considered. We will also discuss the difficulties and limitations of compiling ESP estimates from the literature as well as characterizing fundamentally unsteady volcanic events by a single value for each ESP.
Published: 2020
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26. Quantifying the Uncertainty of a Coupled Plume and Tephra Dispersal Model: PLUME‐MOM/HYSPLIT Simulations Applied to Andean Volcanoes

Author: Arnaud Guillin, Olivier Roche, Pablo Samaniego, M. de' Michieli Vitturi, Silvana Hidalgo, Alessandro Tadini, Federica Pardini, Benjamin Bernard, Mathieu Gouhier, Nourddine Azzaoui, Julia Eychenne, J. L. Le Pennec, Istituto Nazionale di Geofisica e Vulcanologia – Sezione di Pisa (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Instituto Geofísico, Escuela Politécnica Nacional, Quito, Ecuador, Laboratoire de Mathématiques Blaise Pascal (LMBP), Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), ANR-16-IDEX-0001,CAP 20-25,CAP 20-25(2016), ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Advection, Magnitude (mathematics), Atmospheric sciences, 01 natural sciences, Plume, Geophysics, Volcano, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Earth and Planetary Sciences (miscellaneous), HYSPLIT, Environmental science, Biological dispersal, Uncertainty quantification, Tephra, 0105 earth and related environmental sciences
Abstract: Co-auteur étranger; International audience; Numerical modelling of tephradispersaland depositionis essential forevaluation of volcanichazards. Manymodels consider reasonable physical approximations in order toreducecomputational times, but this may introduce a certain degree of uncertainty in the simulation outputs.The important step of uncertainty quantification is dealt in this paper with respect to a coupled version of a plume model (PLUME-MoM) and a tephra dispersal model (HYSPLIT). The performances of this model are evaluated through simulationsoffourpasteruptions of different magnitudesand styles from three Andean volcanoes, and the uncertainty is quantified by evaluating the differences between modeled and observed data of plume height (at different time steps above the vent)as well asmass loading and grain sizeat givenstratigraphic sections.Different meteorological datasets were alsotestedand hada sensible influence on the model outputs. Other results highlight that the modeltendsto underestimate plume heights whileoverestimatingmass loading values, especially for higher magnitude eruptions.Moreover, the advective part of HYSPLIT seems to work more efficiently than the diffusive part.Finally, though the coupledPLUME-MoM/HYSPLIT model generally is less efficient inreproducing deposit grain sizes, we propose itmay be used for hazard maps production for higher magnitude eruptions (sub-Plinian or Plinian)for what concern mass loading.
Published: 2020
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27. Observation of SO2 degassing at Stromboli volcano using a hyperspectral thermal infrared imager

Author: Mathieu Gouhier, Jean-François Smekens, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), ANR-16-IDEX-0001,CAP 20-25,CAP 20-25(2016), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM)
Subjects: 010504 meteorology & atmospheric sciences, Infrared, Multispectral image, 010502 geochemistry & geophysics, 01 natural sciences, Volcanic Gases, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, event, Stromboli, Spectral resolution, Thermal infrared, 0105 earth and related environmental sciences, Remote sensing, event.disaster_type, geography, geography.geographical_feature_category, Hyperspectral imager, Detector, Hyperspectral imaging, Geophysics, Sulfur dioxide, Volcano, 13. Climate action, Brightness temperature, Volcanic plumes, Geology
Abstract: co-auteur étranger; International audience; Thermal infrared (TIR) imaging is a common tool for the monitoring of volcanic activity. Broadband cameras with increasing sampling frequency give great insight into the physical processes taking place during effusive and explosive event, while Fourier transform infrared (FTIR) methods provide high resolution spectral information used to assess the composition of volcanic gases but are often limited to a single point of interest. Continuing developments in detector technology have given rise to a new class of hyperspectral imagers combining the advantages of both approaches. In this work, we present the results of our observations of volcanic activity at Stromboli volcano with a ground-based imager, the Telops Hyper-Cam LW, when used to detect emissions of sulfur dioxide (SO2) produced at the vent, with data acquired at Stromboli volcano (Italy) in early October of 2015. We have developed an innovative technique based on a curve-fitting algorithm to quickly extract spectral information from high-resolution datasets, allowing fast and reliable identification of SO2. We show in particular that weak SO2 emissions, such as inter-eruptive gas puffing, can be easily detected using this technology, even with poor weather conditions during acquisition (e.g., high relative humidity, presence of fog and/or ash). Then, artificially reducing the spectral resolution of the instrument, we recreated a variety of commonly used multispectral configurations to examine the efficiency of four qualitative SO2 indicators based on simple Brightness Temperature Difference (BTD). Our results show that quickly changing conditions at the vent – including but not limited to the presence of summit fog – render the establishment of meaningful thresholds for BTD indicators difficult. Building on those results, we propose recommendations on the use of multispectral imaging for SO2 monitoring and routine measurements from ground-based instruments.
Published: 2018
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28. SO2 and tephra emissions during the December 22, 2018 Anak Krakatau flank-collapse eruption

Author: Mathieu Gouhier, Raphaël Paris, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), ANR-16-IDEX-0001,CAP 20-25,CAP 20-25(2016), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)
Subjects: Daytime, 010504 meteorology & atmospheric sciences, Geochemistry, Geology, 010502 geochemistry & geophysics, 01 natural sciences, Anak Krakatau, Plume, Atmosphere, Geophysics, 13. Climate action, Geochemistry and Petrology, Magma, Subaerial, Earth and Planetary Sciences (miscellaneous), Phreatomagmatic eruption, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Tephra, Volcanic ash, SO2 degassing, Flank Collapse, 0105 earth and related environmental sciences
Abstract: On December 22, 2018 the south-western flank of Anak Krakatau collapsed into the sea, removing 93.8 × 106 m3 of subaerial lavas, and generated a tsunami. Synchronously with the collapse, a large volcanic plume of SO2 and ash (14–15 km in height) has formed, marking the onset of a paroxysmal eruption lasting from December 22, 2018 to January 06, 2019. From remote sensing analysis, we show that the eruption can be divided into three main phases. Phase I and II show both tephra and gas emissions while phase III is mostly degassing. The total amount of SO2 injected in the atmosphere is 173±52 kt, while the minimum bulk magma volume emplaced, estimated from a topographic reconstruction, is ?45 × 106 m3. This value compares well with a petrologic-based estimate of 56.4 × 106 m3, making the existence of external sulphur sources and sinks quite unlikely. The ice-rich ash plume formation shows that a strong sea-water/magma interaction was responsible for the phreatomagmatic activity throughout the eruption. However, we distinguish a first Vulcanian blast-derived eruption (lasting 40 min) just after the collapse having a Mass Eruption Rate (MER) of 9 × 105 kgs?1, followed by a sustained lower-intensity eruption resulting in ash emissions over hours (MER = 5 × 105 kgs?1). From December 23, daytime photos show typical Surtseyan activity.
Published: 2019
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29. Reconstruction of the 2014-2015 FOGO Volcano (Cape Verde) Eruption Through Thermal Remotely Sensed Imagery

Author: Sandra Heleno, V. Miranda, Pedro Pina, Stéphanie Dumont, and Mathieu Gouhier
Subjects: geography, Vulcanian eruption, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Lava, 010502 geochemistry & geophysics, 01 natural sciences, Cape verde, Volcano, Temporal resolution, Thermal remote sensing, Seismology, Geology, 0105 earth and related environmental sciences
Abstract: A volcanic eruption initiated on 23/Nov/2014 on Fogo Island in Cape Verde (14.91°N, 24.38°W, Figure 1 ) lasted for 78 days until 08/Feb/2015 [1] – [4] . Volcanic eruptions are phenomena with strong heat fluxes due to the release of lava and gases that can be suitably monitored through thermal remote sensing and its principles [5] . The sensors acquiring such type of data have generally a high temporal resolution but a low spatial one. But at the same time, non-thermal imagery captured by other sensors can also be very useful to better understand the ongoing event and track its temporal evolution [6] . Therefore, we propose a methodology to reconstruct the 2014-2015 Fogo eruption based on multi-platform imagery.
Published: 2019
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30. Author Correction: Low efficiency of large volcanic eruptions in transporting very fine ash into the atmosphere

Author: Antonio Costa, Nourddine Azzaoui, Arnaud Guillin, Mathieu Gouhier, Mathieu Deslandes, Julia Eychenne, Philippe Husson, Matthieu Poret, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Laboratoire de Mathématiques Blaise Pascal (LMBP), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), and Météo-France
Subjects: geography, Multidisciplinary, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Earth science, lcsh:R, lcsh:Medicine, 010502 geochemistry & geophysics, 01 natural sciences, Computer Science::Digital Libraries, Atmosphere, Volcano, [SDU]Sciences of the Universe [physics], ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, lcsh:Q, lcsh:Science, Author Correction, Geology, 0105 earth and related environmental sciences
Abstract: Volcanic ash clouds are common, often unpredictable, phenomena generated during explosive eruptions. Mainly composed of very fine ash particles, they can be transported in the atmosphere at great distances from the source, having detrimental socio-economic impacts. However, proximal settling processes controlling the proportion (ε) of the very fine ash fraction distally transported in the atmosphere are still poorly understood. Yet, for the past two decades, some operational meteorological agencies have used a default value of ε = 5% as input for forecast models of atmospheric ash cloud concentration. Here we show from combined satellite and field data of sustained eruptions that ε actually varies by two orders of magnitude with respect to the mass eruption rate. Unexpectedly, we demonstrate that the most intense eruptions are in fact the least efficient (with ε = 0.1%) in transporting very fine ash through the atmosphere. This implies that the amount of very fine ash distally transported in the atmosphere is up to 50 times lower than previously anticipated. We explain this finding by the efficiency of collective particle settling in ash-rich clouds which enhance early and en masse fallout of very fine ash. This suggests that proximal sedimentation during powerful eruptions is more controlled by the concentration of ash than by the grain size. This has major consequences for decision-makers in charge of air traffic safety regulation, as well as for the understanding of proximal settling processes. Finally, we propose a new statistical model for predicting the source mass eruption rate with an unprecedentedly low level of uncertainty.
Published: 2019
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31. Indo-French High-resolution Thermal Infrared Space Mission for Earth Natural Resources Assessment and Monitoring -Concept and Definition of TRISHNA

Author: G. Boulet, Isabelle Dadou, Philippe Gamet, J.-L. Roujean, D. Adlakha, M. R. Pandya, Olivier Hagolle, M. Irvine, Muddu Sekhar, Frédéric Jacob, Bimal K. Bhattacharya, S. K. Singh, Rahul Nigam, M. V. Shukla, Benoit Laignel, Jean-Pierre Lagouarde, Mathieu Gouhier, Philippe Maisongrande, Xavier Briottet, Manoj Kumar Mishra, Gérard Dedieu, Catherine Ottlé, Albert Olioso, S. Suresh Babu, Ratheesh Ramakrishnan, K. K. Kumar, Philippe Crebassol, P. V. Raju, Kaniska Mallick, C. S. Murthy, José A. Sobrino, S. S. Sarkar, Institut National de la Recherche Agronomique (INRA), Indian Space Research Organisation (ISRO), Morphodynamique Continentale et Côtière (M2C), Centre National de la Recherche Scientifique (CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Indian Institute of Science, Interactions Sol Plante Atmosphère (UMR ISPA), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro), Centre National d'Études Spatiales [Toulouse] (CNES), Institut de Recherche pour le Développement (IRD), ONERA / DOTA, Université de Toulouse [Toulouse], ONERA-PRES Université de Toulouse, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Centre d'études spatiales de la biosphère (CESBIO), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire d'étude des Interactions Sol - Agrosystème - Hydrosystème (UMR LISAH), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Luxembourg Institute of Science and Technology (LIST), Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes (EMMAH), Institut National de la Recherche Agronomique (INRA)-Avignon Université (AU), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation des Surfaces et Interfaces Continentales (MOSAIC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Valence, University of Valencia, International Society for Photogrammetry and Remote Sensing (ISPRS). INT., Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Universitat de València (UV)
Subjects: lcsh:Applied optics. Photonics, 010504 meteorology & atmospheric sciences, 0207 environmental engineering, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 02 engineering and technology, 01 natural sciences, lcsh:Technology, global monitoring, Evapotranspiration, Nadir, 020701 environmental engineering, 0105 earth and related environmental sciences, Remote sensing, TIR remote sensing, surface energy balance, TRISHNA mission, Spacecraft, business.industry, lcsh:T, Primary production, lcsh:TA1501-1820, Natural resource, 13. Climate action, lcsh:TA1-2040, Environmental science, Radiometry, Satellite, business, lcsh:Engineering (General). Civil engineering (General), Water use
Abstract: The Indian and French Space Agencies, ISRO and CNES, have conceptualized a space-borne Thermal Infrared Reflectance (TIR) mission, TRISHNA (Thermal infRared Imaging Satellite for High-resolution Natural Resource Assessment). The primary design drivers of TRISHNA are the monitoring of (i) terrestrial water stress and use, and of (ii) coastal and continental water. A suit of four TIR bands and six optical bands is planned. The TIR bands will be centred at 8.6 μm, 9.1 μm, 10.3 μm and 11.5 μm to provide noon-night global observations at 57m nadir resolution over land and coastal regions. The field of view (FOV) is ±34° and the orbit of 761 km altitude was designed to allow 3 sub-cycle acquisitions during the 8-day cycle. The optical bands correspond to blue, green, red, and NIR plus two SWIR bands at 1.38 μm and 1.61 μm. The green, red, NIR and the 1.61 μm SWIR bands will have better radiometry quality than those of AWiFS. ISRO and CNES will develop optical and TIR payloads, respectively. Assessing evapotranspiration and furthermore Gross and Net Primary Productivity (GPP and NPP) will in turn assist in quantifying water use in rainfed and irrigated agriculture, water stress and water use efficiency, with expected applications to agricultural drought and early warning, crop yield prediction, water allocation, implementation of water rights, crop insurance business and agro-advisories to farmers. The other scientific objectives of TRISHNA are also briefly described. TRISHNA instrument will fly aboard a ISRO spacecraft scheduled to be launched from 2024 for a minimum period of 5 years’ mission lifetime.
Published: 2019
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32. The Indian-French Trishna Mission: Earth Observation in the Thermal Infrared with High Spatio-Temporal Resolution

Author: Benoit Laignel, Isabelle Dadou, Bimal K. Bhattacharya, Mathieu Gouhier, Xavier Briottet, José A. Sobrino, Albert Olioso, Philippe Gamet, Anil Kumar, Frédéric Jacob, S. K. Singh, G. Boulet, M. Irvine, Muddu Sekhar, Ratheesh Ramakrishnan, K. K. Kumar, Gérard Dedieu, Catherine Ottlé, S. Cherchali, J.-L. Roujean, S. Suresh Babu, C. S. Murthy, Olivier Hagolle, Krishna Mohan Buddhiraju, M. R. Pandya, P. V. Raju, Philippe Crebassol, M. V. Shukla, Kaniska Mallick, Jean-Pierre Lagouarde, Laboratoire de recherche en Hydrodynamique, Énergétique et Environnement Atmosphérique (LHEEA), École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Indian Space Research Organisation (ISRO), Centre National d'Études Spatiales [Toulouse] (CNES), Space Physics Laboratory, Centre d'études spatiales de la biosphère (CESBIO), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), ONERA / DOTA, Université de Toulouse [Toulouse], ONERA-PRES Université de Toulouse, Space technology cell (ISRO, ITT(B)), DYNBIO LEGOS, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP), Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen (GREYC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'étude des Interactions Sol - Agrosystème - Hydrosystème (UMR LISAH), Institut de Recherche pour le Développement (IRD)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut de Recherche pour le Développement (IRD [ Madagascar])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), School of Medicine and Health Sciences [George Washigton University] (SMHS), George Washington University (GW), Morphodynamique Continentale et Côtière (M2C), Centre National de la Recherche Scientifique (CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Institut de Physique Théorique - UMR CNRS 3681 (IPHT), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Luxembourg Institute of Science and Technology (LIST), National Remote Sensing Centre [Hyderabad] (NRSC), Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes (EMMAH), Avignon Université (AU)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Indian Institute of Science, Foundation for Innovation and Technology Transfer (FITT), Indian Institute of Technology Delhi (IIT Delhi), Global Change Unit, University of Valencia, Universitat de València (UV), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), The George Washington University (GW), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation des Surfaces et Interfaces Continentales (MOSAIC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institute of Electrical and Electronics Engineers (IEEE). USA., Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Interactions Sol Plante Atmosphère (ISPA), Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro)-Institut National de la Recherche Agronomique (INRA), ISRO, Centre National d’Etudes Spatiales, Space Phys Lab, Vikram Sarabhai Space Ctr, Institut de Recherche pour le Développement (IRD [Réunion]), Université de Toulouse, Institut de Recherche pour le Développement (IRD), Université de Rouen Normandie (UNIROUEN), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: Earth observation, 010504 meteorology & atmospheric sciences, INFRAROUGE, CLIMATE CHANGE, WATER MANAGEMENT, 0211 other engineering and technologies, Climate change, 02 engineering and technology, 01 natural sciences, [SDV.BV]Life Sciences [q-bio]/Vegetal Biology, WATER STRESS, Water cycle, Thermal infrared, Baseline (configuration management), SATELLITE, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Remote sensing, THERMAL, [SDE.IE]Environmental Sciences/Environmental Engineering, INFRARED, Spectral bands, MISSION SPATIALE, Natural resource, 13. Climate action, Temporal resolution, [SDE]Environmental Sciences, Environmental science, Satellite
Abstract: International audience; The monitoring of the water cycle at the Earth surface which tightly interacts with the climate change processes as well as a number of practical applications (agriculture, soil and water quality assessment, irrigation and water resource management, etc...) requires surface temperature measurements at local scale. Such is the goal of the Indian-French high spatio-temporal TRISHNA mission (Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment). The scientific objectives of the mission and research work conducted to consolidate the mission specifications are presented. Progress in modelling of surface fluxes is then discussed. The main specifications of the mission such as the revisit, the spatial resolution, the overpass time, the spectral bands and the orbit are analyzed and justified. The resulting baseline of the mission is given.
Published: 2018
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33. Elevated gas flux and trace metal degassing from the 2014-2015 fissure eruption at the Bárðarbunga volcanic system, Iceland

Author: Pierre-Jean Gauthier, Baptiste Haddadi, Olgeir Sigmarsson, Mathieu Gouhier, and Séverine Moune
Subjects: geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Lava, Earth science, Trace element, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), chemistry.chemical_compound, Geophysics, Flux (metallurgy), chemistry, Volcano, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, Carbon dioxide, Earth and Planetary Sciences (miscellaneous), Trace metal, Petrology, Geology, 0105 earth and related environmental sciences, Melt inclusions
Abstract: The 2014 Barðarbunga rifting event in Iceland resulted in a 6-month long eruption at Holuhraun. This eruption was characterized by high lava discharge rate and significant gas emission. The SO2 flux for the first 3 months was measured with satellite sensors and the petrologic method. High-resolution time series of the satellite data give 1200 kg/s that concurs with 1050 kg/s obtained from melt inclusion minus degassed lava sulfur contents scaled to the mass of magma produced. A high-purity gas sample, with elevated S/Cl due to limited chlorine degassing, reveals a similar degassing pattern of trace metals as observed at Kīlauea (Hawai'i) and Erta Ale (Ethiopia). This suggests a common degassing mechanism at mantle plume-related volcanoes. The trace metal fluxes, calculated from trace element to sulfur ratios in the gas sample and scaled to the sulfur dioxide flux, are 1–2 orders of magnitude stronger at Holuhraun than Kīlauea and Erta Ale. In contrast, volcanoes at convergent margins (Etna and Stromboli, Italy) have 1–2 orders of magnitude higher trace element fluxes, most likely caused by abundant chlorine degassing. This emphasizes the importance of metal degassing as chlorine species. Short-lived disequilibria between radon daughters, 210Pb-210Bi-210Po measured in the gas, suggest degassing of a continuously replenished magma batch beneath the eruption site. Earlier and deep degassing phase of carbon dioxide and polonium is inferred from low (210Po/210Pb) in the gas, consistent with magma transfer rate of 0.75 m/s.
Published: 2016
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34. HOTVOLC: a web-based monitoring system for volcanic hot spots

Author: Mathieu Gouhier, S. Rivet, Philippe Cacault, Philippe Labazuy, J. Decriem, and Yannick Guéhenneux
Subjects: geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, business.industry, Geology, Ocean Engineering, Monitoring system, 010502 geochemistry & geophysics, 01 natural sciences, Volcano, Web application, business, 0105 earth and related environmental sciences, Water Science and Technology, Remote sensing
Published: 2016
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35. The geometry of Strombolian explosions: insights from Doppler radar measurements

Author: Franck Donnadieu and Mathieu Gouhier
Subjects: Jet (fluid), 010504 meteorology & atmospheric sciences, Doppler radar, Geometry, 010502 geochemistry & geophysics, 01 natural sciences, Strombolian eruption, Spectral line, Physics::Geophysics, law.invention, symbols.namesake, Geophysics, Impact crater, 13. Climate action, Geochemistry and Petrology, law, symbols, Dispersion (water waves), Ejecta, Doppler effect, Geology, 0105 earth and related environmental sciences
Abstract: SUMMARY Observations of Strombolian volcanic explosions were carried out at Etna's southeast crater on 2001 July 4 using a ground-based pulsed Doppler radar (VOLDORAD). To obtain quantitative constraints on the geometry of the explosions, we modelled synthetic Doppler spectra by combining the outputs of a ballistic model to compute the theoretical velocities of gas and particles, and an electromagnetic scattering model to calculate the synthetic echo power. This allowed us to reproduce the shapes of recorded Doppler spectra for each volcanic explosion. We examined the geometrical distribution of ejected pyroclasts for about 200 explosions and found two main types of explosion, each showing a distinctive spectral signature. The first type, characterized by the triangular shape of their Doppler spectra, represents 34 per cent of the explosions. This spectrum shape is related to a Gaussian distribution of the pyroclast ejection angles, where most of the volcanic material is ejected vertically within a narrow cone, with the particle concentration decreasing radially. The second type represents about 12 per cent of the explosions, and is characterized by a top-hat-shaped spectrum. It is produced by a uniform distribution of pyroclast ejection angles. In this case, the bubbles tend to burst above the crater rim and eject the ballistic clasts hemispherically without preferential orientation. The majority of the Strombolian explosions analysed (54 per cent) are intermediate between these end-member shapes, and show a triangular spectra truncated by a plateau. They result from a uniform distribution of ejection angles around the jet axis. The continuous radar recordings allowed us to carry out a statistical analysis on the geometrical features of the same 200 Strombolian explosions. Thus we find that 40° is a statistically representative aperture of the dispersion cone characterized by uniform ejecta distribution for explosions having a plateau component (i.e. 2/3 of all explosions studied). We also find that 80 per cent of the total particle load remains within this 40° dispersion cone, which in our case is oriented nearly vertically. Such quantification of the geometrical features of Strombolian explosions can provide constraints on shallow conduit processes. For example, the time evolution of the top-hat Doppler spectra during the paroxysm suggests that the magma level varies over a 15 min timescale.
Published: 2010
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36. A year of lava fountaining at Etna: Volumes from SEVIRI

Author: Gaetana Ganci, Philippe Labazuy, Sonia Calvari, Mathieu Gouhier, C. Del Negro, Yannick Guéhenneux, Andrew J. L. Harris, and Annalisa Cappello
Subjects: Maximum intensity, 010504 meteorology & atmospheric sciences, Meteorology, Lava, Radiant heat flux, 010502 geochemistry & geophysics, Geodesy, 01 natural sciences, Geophysics, 13. Climate action, Temporal resolution, General Earth and Planetary Sciences, High temporal resolution, Geology, 0105 earth and related environmental sciences
Abstract: [1] We present a new method that uses cooling curves, apparent in high temporal resolution thermal data acquired by geostationary sensors, to estimate erupted volumes and mean output rates during short lava fountaining events. The 15 minute temporal resolution of the data allows phases of waxing and peak activity to be identified during short (150-to-810 minute-long) events. Cooling curves, which decay over 8-to-21 hour-periods following the fountaining event, can also be identified. Application to 19 fountaining events recorded at Etna by MSG's SEVIRI sensor between 10 January 2011 and 9 January 2012, yields a total erupted dense rock lava volume of ∼28 × 106 m3, with a maximum intensity of 227 m3 s−1being obtained for the 12 August 2011 event. The time-averaged output over the year was 0.9 m3 s−1, this being the same as the rate that has characterized Etna's effusive activity for the last 40 years.
Published: 2012
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37. Eyjafjallajökull ash concentrations derived from both lidar and modeling

Author: Patrick Chazette, Jean-Christophe Raut, Marc Bocquet, Mélody Lardier, Philippe Royer, Jean-Pierre Cariou, Victor Winiarek, Mathieu Gouhier, and Philippe Labazuy
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Soil Science, Aquatic Science, 010502 geochemistry & geophysics, Oceanography, Atmospheric sciences, Eulerian model, 01 natural sciences, Geochemistry and Petrology, Wind lidar, Earth and Planetary Sciences (miscellaneous), 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, geography, Satellite observation, geography.geographical_feature_category, Ecology, Paleontology, Forestry, Plume, Aerosol, Geophysics, Lidar, Volcano, 13. Climate action, Space and Planetary Science, Environmental science, Satellite
Abstract: [1] Following the eruption of the Icelandic volcano Eyjafjallajokull on the 14 April 2010, ground-based N2-Raman lidar (GBL) measurements were used to trace the temporal evolution of the ash plume from 16 to 20 April 2010 above the southwestern suburb of Paris. The nighttime overpass of the Cloud-Aerosol LIdar with Orthogonal Polarization onboard Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation satellite (CALIPSO/CALIOP) on 17 April 2010 was an opportunity to complement GBL observations. The plume shape retrieved from GBL has been used to assess the size range of the particles size. The lidar-derived aerosol mass concentrations (PM) have been compared with model-derived PM concentrations held in the Eulerian model Polair3D transport model, driven by a source term inferred from the SEVIRI sensor onboard Meteosat satellite. The consistency between model and ground-based wind lidar and CALIOP observations has been checked. The spatial and temporal structures of the ash plume as estimated by each instrument and by the Polair3D simulations are in agreement. The ash plume was associated with a mean aerosol optical thickness of 0.1 ± 0.06 and 0.055 ± 0.053 for GBL (355 nm) and CALIOP (532 nm), respectively. Such values correspond to ash mass concentrations of ∼400 ± 160 and ∼720 ± 670 μg m−3, respectively, within the ash plume, which was lower than 0.5 km in width. The relative uncertainty is ∼75% and mainly due to the assessment of the specific cross-section assuming an aerosol density of 2.6 g cm−3. The simulated ash plume is smoother leading to integrated mass of the same order of magnitude (between 50 and 250 mg m−2).
Published: 2012
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38. Causes and consequences of bimodal grain-size distribution of tephra fall deposited during the August 2006 Tungurahua eruption (Ecuador)

Author: Mathieu Gouhier, Julia Eychenne, Jean-Luc Le Pennec, Liliana Troncoso, Jean-Marie Nedelec, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), instituto Geofísico, Escuela Politécnica Nacional (EPN), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie de Clermont-Ferrand (ICCF), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-SIGMA Clermont (SIGMA Clermont)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), MI, and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-SIGMA Clermont (SIGMA Clermont)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-SIGMA Clermont (SIGMA Clermont)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Tungurahua volcano, Eruption type, Volcanic Explosivity Index, Tephra fall, Bimodal grain size, Eruption type, Geochemistry, Pyroclastic rock, Volcanic explosivity index, 010502 geochemistry & geophysics, 01 natural sciences, Volcanic Explosivity Index, Bimodal grain size, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Tephra, Geomorphology, Tephra fall, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Tungurahua volcano, Lapilli, Plume, Volcano, 13. Climate action, Scoria, Geology, Volcanic ash
Abstract: International audience; The violent August 16-17, 2006 Tungurahua eruption in Ecuador witnessed the emplacement of numerous scoria flows and the deposition of a widespread tephra layer west of the volcano. We assess the size of the eruption by determining a bulk tephra volume in the range 42-57 × 106 m3, which supports a Volcanic Explosivity Index 3 event, consistent with calculated column height of 16-18 km above the vent and making it the strongest eruptive phase since the volcano's magmatic reactivation in 1999. Isopachs west of the volcano are sub-bilobate in shape, while sieve and laser diffraction grain-size analyses of tephra samples reveal strongly bimodal distributions. Based on a new grain-size deconvolution algorithm and extended sampling area, we propose here a mechanism to account for the bimodal grain-size distribution. The deconvolution procedure allows us to identify two particle subpopulations in the deposit with distinct characteristics that indicate dissimilar transport-depositional processes. The log-normal coarse-grained subpopulation is typical of particles transported downwind by the main volcanic plume. The positively skewed, fine-grained subpopulation in the tephra fall layer shares close similarities with the elutriated co-pyroclastic flow ash cloud layers preserved on top of the scoria flow deposits. The area with the higher fine particle content in the tephra layer coincides with the downwind prolongation of the pyroclastic flow deposits. These results indicate that the bimodal distribution of grain size in the Tungurahua fall deposit results from synchronous deposition of lapilli from the main plume and fine ash elutriated from scoria flows emplaced on the western flank of the volcano. Our study also reveals that inappropriate grain-size data processing may produce misleading determination of eruptive type.
Published: 2012
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39. Physical and optical properties of 2010 Eyjafjallajökull volcanic eruption aerosol: ground-based, Lidar and airborne measurements in France

Author: Boris Quennehen, Philippe Labazuy, Patrick Fréville, Nina Iren Kristiansen, Andreas Stohl, Jean-Marc Pichon, Karine Sellegri, David Picard, J. Boulon, Aurélie Colomb, Mathieu Gouhier, Maxime Hervo, Jean-Claude Roger, Alfons Schwarzenboeck, Laboratoire de météorologie physique (LaMP), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Norwegian Institute for Air Research (NILU), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Laboratoire Magmas et Volcans (LMV), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP), Laboratoire de Physico-Chimie de l'Atmosphère (LPCA), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale, Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Chercheur indépendant, Laboratoire de Météorologie Physique - Clermont Auvergne (LaMP), Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, Angstrom exponent, 010504 meteorology & atmospheric sciences, Planetary boundary layer, [SDE.MCG]Environmental Sciences/Global Changes, Atmospheric sciences, 01 natural sciences, 010309 optics, Troposphere, lcsh:Chemistry, 0103 physical sciences, Mass concentration (chemistry), ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [PHYS]Physics [physics], [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], lcsh:QC1-999, Plume, Aerosol, Lidar, lcsh:QD1-999, 13. Climate action, [SDU]Sciences of the Universe [physics], [SDE]Environmental Sciences, Environmental science, lcsh:Physics, Volcanic ash
Abstract: During the Eyjafjallajökull eruption (14 April to 24 May 2010), the volcanic aerosol cloud was observed across Europe by several airborne in situ and ground-based remote-sensing instruments. On 18 and 19 May, layers of depolarizing particles (i.e. non-spherical particles) were detected in the free troposphere above the Puy de Dôme station, (PdD, France) with a Rayleigh-Mie LIDAR emitting at a wavelength of 355 nm, with parallel and crossed polarization channels. These layers in the free troposphere (FT) were also well captured by simulations with the Lagrangian particle dispersion model FLEXPART, which furthermore showed that the ash was eventually entrained into the planetary boundary layer (PBL). Indeed, the ash cloud was then detected and characterized with a comprehensive set of in situ instruments at the Puy de Dôme station (PdD). In agreement with the FLEXPART simulation, up to 65 μg m−3 of particle mass and 2.2 ppb of SO2 were measured at PdD, corresponding to concentrations higher than the 95 percentile of 2 yr of measurements at PdD. Moreover, the number concentration of particles increased to 24 000 cm−3, mainly in the submicronic mode, but a supermicronic mode was also detected with a modal diameter of 2 μm. The resulting optical properties of the ash aerosol were characterized by a low scattering Ångström exponent (0.98), showing the presence of supermicronic particles. For the first time to our knowledge, the combination of in situ optical and physical characterization of the volcanic ash allowed the calculation of the mass-to-extinction ratio (η) with no assumptions on the aerosol density. The mass-to-extinction ratio was found to be significantly different from the background boundary layer aerosol (max: 1.57 g m−2 as opposed to 0.33 ± 0.03 g m−2). Using this ratio, ash mass concentration in the volcanic plume derived from LIDAR measurements was found to be 655 ± 23 μg m−3 when the plume was located in the FT (3000 m above the sea level – a.s.l.). This ratio could also be used to retrieve an aerosol mass concentration of 579 ± 60 μg m−3 on 19 April, when LIDAR observations detected the ash cloud at 3000 m a.s.l. in correspondence with model simulations (FLEXPART). On 22 April, another ash plume entered the BL, and although it was more diluted than during the May episode, the French research aircraft ATR42 that passed over Clermont-Ferrand in the PBL confirmed the presence of particles with a supermicronic mode, again with a modal diameter at 2 μm. This data set combining airborne, ground-based and remote sensing observations with dispersion model simulations shows an overall very good coherence during the volcanic eruption period, which allows a good confidence in the characteristics of the ash particles that can be derived from this unique data set.
Published: 2012
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40. An unloading foam model to constrain Etna's 11-13 January 2011 lava fountaining episode

Author: Andrew J. L. Harris, Enzo Boschi, Giuseppe Salerno, Mathieu Gouhier, Emilio Pecora, Philippe Labazuy, Letizia Spampinato, Emilio Biale, A. La Spina, and Sonia Calvari
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Lava, Soil Science, Pyroclastic rock, Aquatic Science, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Impact crater, Geochemistry and Petrology, Satellite data, Earth and Planetary Sciences (miscellaneous), 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, geography, geography.geographical_feature_category, Ecology, Paleontology, Forestry, Pit crater, Strombolian eruption, Geophysics, Etna volcano, Volcano, 13. Climate action, Space and Planetary Science, Geology, Seismology
Abstract: [1] The 11–13 January 2011 eruptive episode at Etna volcano occurred after several months of increasing ash emissions from the summit craters, and was heralded by increasing SO2 output, which peaked at ∼5000 megagrams/day several hours before the start of the eruptive activity. The eruptive episode began with a phase of Strombolian activity from a pit crater on the eastern flank of the SE-Crater. Explosions became more intense with time and eventually became transitional between Strombolian and fountaining, before moving into a lava fountaining phase. Fountaining was accompanied by lava output from the lower rim of the pit crater. Emplacement of the resulting lava flow field, as well as associated lava fountain- and Strombolian-phases, was tracked using a remote sensing network comprising both thermal and visible cameras. Thermal surveys completed once the eruptive episode had ended also allowed us to reconstruct the emplacement of the lava flow field. Using a high temporal resolution geostationary satellite data we were also able to construct a detailed record of the heat flux during the fountain-fed flow phase and its subsequent cooling. The dense rock volume of erupted lava obtained from the satellite data was 1.2 × 106 m3; this was emplaced over a period of about 6 h to give a mean output rate of ∼55 m3 s−1. By comparison, geologic data allowed us to estimate dense rock volumes of ∼0.85 × 106 m3 for the pyroclastics erupted during the lava fountain phase, and 0.84–1.7 × 106 m3 for lavas erupted during the effusive phase, resulting in a total erupted dense rock volume of 1.7–2.5 × 106 m3 and a mean output rate of 78–117 m3 s−1. The sequence of events and quantitative results presented here shed light on the shallow feeding system of the volcano.
Published: 2011
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41. Systematic retrieval of ejecta velocities and gas fluxes at Etna volcano using L-Band Doppler radar

Author: Mathieu Gouhier, Franck Donnadieu, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: L band, 010504 meteorology & atmospheric sciences, Gas velocity, [SDE.MCG]Environmental Sciences/Global Changes, Doppler radar, Gas fluxes, 010502 geochemistry & geophysics, 01 natural sciences, Acquisition rate, law.invention, Jet velocity, Geochemistry and Petrology, law, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Ejecta, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Particle sizes, Ejecta velocities, Etna volcano, 13. Climate action, Particle diameter, Ejecta velocities Gas fluxes Etna volcano Doppler radar Particle sizes, Atomic physics, Geology, Seismology
Abstract: Strombolian-type volcanic activity is characterized by a series of gas bubbles bursting at the top of a magma column and leading to the ejection of lava clots and gas emission at the surface. The quantitative analysis of physical parameters (e.g., velocity, size, and mass fluxes) controlling the emission dynamics of these volcanic products is very important for the understanding of eruption source mechanisms but remains difficult to obtain in a systematic fashion. Ground-based Doppler radar is found to be a very effective tool for measuring ejecta velocities at a high acquisition rate and close to the emission source. We present here a series of measurements carried out at Mt. Etna’s Southeast crater, using an L-band volcanological Doppler radar, during the 4 July 2001 Strombolian eruptions. Doppler radar data are supplemented by the analysis of video snapshots recorded simultaneously. We provide here a set of physical parameters systematically retrieved from 247 Strombolian explosions spanning 15 min and occurring during the paroxysm of the eruption from 21:30 to 21:45 UT. The time-average values give a maximum particle velocity of \( V_{{\max }}^p = {94}.{7}\pm {24} {\text{m/s}} \), a bulk lava jet velocity of \( {V_{{{\text{PW - rad}}}}} = {37}.{6}\pm {1}.{9} {\text{m/s}} \), and an initial gas velocity at the source vent of \( V_0^g = {118}.{4}\pm {36} {\text{m/s}} \). The time-averaged particle diameter is found to be about \( {D_{{{\text{PW - rad}}}}} = {4}.{2}\pm {2}.{1} {\text{cm}} \). The volume and mass gas fluxes are estimated from time-averaged source gas velocities over the sequence duration at \( Q_v^g = {3} - {11} \times {1}{0^{{3}}}{{\text{m}}^{{3}}}{\text{/s}} \) and \( Q_m^g = 0.{5} - {2} \times {1}{0^{{3}}}{\text{kg/s}} \), respectively.
Published: 2011
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42. Tephra sedimentation during the 2010 Eyjafjallajökull eruption (Iceland) from deposit, radar, and satellite observations

Author: Riccardo Genco, Mathieu Gouhier, Marco Pistolesi, Raffaello Cioni, F. Alfano, Ármann Höskuldsson, Maurizio Ripepe, and Costanza Bonadonna
Subjects: Atmospheric Science, Doppler radar, Soil Science, explosive volcanism, Aquatic Science, Oceanography, Atmospheric sciences, Sphericity, law.invention, Atmosphere, Settling, Geochemistry and Petrology, law, Earth and Planetary Sciences (miscellaneous), ddc:550, weak plumes, Tephra, Earth-Surface Processes, Water Science and Technology, geography, geography.geographical_feature_category, Plateau, Eyjafjallajökull, Ecology, settling velocity, particle aggregation, Paleontology, Forestry, Geophysics, Sedimentation, PLUDIX, Volcano, Space and Planetary Science, MSG-SEVIRI, tephra deposits, Geology
Abstract: The April-May 2010 eruption of Eyjafjallajokull volcano (Iceland) was characterized by a nearly continuous injection of tephra in the atmosphere that affected various economic sectors in Iceland and caused a global-wide interruption of air traffic. Eruptive activity during 4-8 May 2010 was characterized based on short-duration physical parameters in order to capture transient eruptive behavior of a long-lasting eruption (i.e., total grainsize distribution, erupted mass and mass eruption rate averaged over 30-minute activity). Resulting 30-minute total grainsize distribution based on both ground and MSG-SEVIRI satellite measurements is characterized by Mdphi of about 2 phi and a fine-ash content of about 30wt%. Accumulation rate varied by two orders of magnitude with an exponential decay away from the vent, whereas Mdphi shows a linear increase until about 18 km from vent reaching a plateau of about 4.5 phi between 20-56 km. Associated mass eruption rate is in between 0.6-1.2 x 10^5 kg s^-1. In-situ sampling showed how fine ash mainly fell as aggregates of various typologies. About 5 to 9 wt% of the erupted mass remained in the cloud up to 1000 km from the vent, suggesting that nearly half of the ash >7 phi settled as aggregates within the first 60 km. Particle sphericity and shape factor varied between 0.4 and 1 with no clear correlation with size and distance from vent. Our experiments also demonstrate how satellite retrievals and Doppler radar grainsize detection can provide real-time description of the source term but for a limited particle-size range.
Published: 2011

43. Satellite-based evidence for a large hydrothermal system at Piton de la Fournaise volcano (Reunion Island)

Author: Diego Coppola and Mathieu Gouhier
Subjects: geography, Geophysics, geography.geographical_feature_category, Volcano, Impact crater, Lava, Geochemistry, General Earth and Planetary Sciences, Satellite, Hydrothermal circulation, Geology, Seismology
Abstract: [1] Hydrothermal systems are active structures present at many volcanoes. Their characterization is essential as they reveal the evolution of the magmatic source and may play a role in the eruptive style. Many studies have already suggested the existence of a shallow hydrothermal system beneath the summit craters at Piton de la Fournaise volcano (La Reunion), although there is still no clear evidence. Here we present new arguments on the basis of satellite-based data acquired during April 2007 eruption suggesting the existence of a large hydrothermal system beneath the Dolomieu crater at Piton de la Fournaise. SO2 released during the collapse phase of the Dolomieu crater (∼April 6–13) has been estimated at 935 ± 244 kilotons whereas erupted SO2 calculated from lava effusion rates was found to be clearly insufficient (179 ± 89 kilotons). We suggest that the excess of SO2 originated from a large hydrothermal system suddenly opened by the collapse.
Published: 2011
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44. Mass estimations of ejecta from Strombolian explosions by inversion of Doppler radar measurements

Author: Franck Donnadieu, Mathieu Gouhier, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Mass flux, Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Doppler radar, Soil Science, Mineralogy, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Aquatic Science, 010502 geochemistry & geophysics, Oceanography, Kinetic energy, 01 natural sciences, 7. Clean energy, law.invention, Geochemistry and Petrology, law, Earth and Planetary Sciences (miscellaneous), Ejecta, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Weibull distribution, Physics, Ecology, Paleontology, Forestry, Strombolian eruption, Geophysics, 13. Climate action, Space and Planetary Science, Particle-size distribution, Log-normal distribution
Abstract: [1] We present a new method for estimating particle loading parameters (mass, number, volume) of eruptive jets by inversion of echo power data measured using a volcano Doppler radar (VOLDORAD) during typical Strombolian activity from the southeast (SE) crater of Mount Etna on 4 July 2001. Derived parameters such as mass flux, particle kinetic and thermal energy, and particle concentration are also estimated. The inversion algorithm uses the complete Mie (1908) formulation of electromagnetic scattering by spherical particles to generate synthetic backscattered power values. In a first data inversion model (termed the polydisperse model), the particle size distribution (PSD) is characterized by a scaled Weibull function. The mode of the distribution is inferred from particle terminal velocities measured by Doppler radar for each explosion. The distribution shape factor is found to be 2.3 from Chouet et al.’s (1974) data for typical Strombolian activity, corresponding to the lognormal PSDs commonly characteristic of other Strombolian deposits. The polydisperse model inversion converges toward the Weibull scale factor producing the best fit between synthetic and measured backscattered power. A cruder, alternative monodisperse model is evaluated on the basis of a single size distribution assumption, the accuracy of which lies within 25% of that of the polydisperse model. Although less accurate, the monodisperse model, being much faster, may be useful for rapid estimation of physical parameters during real-time volcano monitoring. Results are illustrated for two explosions at Mount Etna with contrasted particle loads. Estimates from the polydisperse model give 58,000 and 206,000 kg as maxima for the total mass of pyroclasts, 26,400 and 73,600 kg s � 1 for mass flux rates, 38 and 135 m 3 (22 and 76 m 3 equivalent magma volume) for the pyroclast volumes, and 0.02–0.4 and 0.06–0.12 kg m � 3 for particle concentrations, respectively. The time-averaged kinetic energy released is found to be equal to 4.2 � 10 7 and 3.9 � 10 8 J, and thermal energy is estimated at 8.4 � 10 10 and 3 � 10 11 J.
Published: 2008
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45. Erratum to: Lava discharge during Etna’s January 2011 fire fountain tracked using MSG-SEVIRI

Author: Sonia Calvari, Mathieu Gouhier, Sébastien Valade, Andrew J. L. Harris, Yannick Guéhenneux, Philippe Labazuy, and Franck Donnadieu
Subjects: geography, geography.geographical_feature_category, Meteorology, Lava, Doppler radar, law.invention, Volcano, Impact crater, Etna volcano, Geochemistry and Petrology, law, Radar, Fountain, Geology
Abstract: In the paper by Gouhier, M., Harris, A., Calvari, S., Labazuy, P., Guehenneux, Y., Donnadieu, F., Valade, S, entitled “Lava discharge during Etna’s January 2011 fire fountain tracked using MSG-SEVIRI” (Bull Volcanol (2012) 74:787–793, DOI 10.1007/s00445-011-0572-y), we present data from a Doppler radar (VOLDORAD 2B). This ground-based Lband radar has been monitoring the eruptive activity of the summit craters of Mt. Etna in real-time since July 2009 from a site about 3.5 km SSE of the craters. Examples of applications of this type of radar are reviewed by Donnadieu (2012) and shown on the VOLDORAD website (http://wwwobs. univbpclermont.fr/SO/televolc/voldorad/). Although designed and owned by the Observatoire de Physique du Globe in Clermont-Ferrand (OPGC), France, VOLDORAD 2B is operated jointly with the INGV-Catania (Italy) in the framework of a technical and scientific collaboration agreement between the INGV of Catania, the French CNRS and the OPGC-Universite Blaise Pascal in ClermontFerrand. The system also utilizes a dedicated micropatch antenna designed at the University of Calabria (Boccia et al. 2010) and owned by INGV. The objective of the joint acquisition of the radar data by INGV-Catania and the OPGC is twofold: (1) to mitigate volcanic risks at Etna by better assessing the hazards arising from ash plumes and (2) to allow detailed study of volcanic activity and its environmental impact. In the paper by Gouhier et al. (2012), we failed to highlight this important collaboration between the INGV Catania and the OPGC; a cooperation essential for the past, current and future generation of such valuable data sets. Specifically we wish to acknowledge the roles of Mauro Coltelli, Michele Prestifilippo and Simona Scollo for their important input into this project, and pivotal role in setting up, and maintaining, this collaborative deployment.
Published: 2012
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46. Near real-time monitoring of the April-May 2010 Eyjafjallajökull ash cloud: an example of a web-based, satellite data-driven, reporting system

Author: S. Rivet, Andrew J. L. Harris, Jean Claude Bergès, Philippe Cacault, Yannick Guéhenneux, Maxime Hervo, Patrick Fréville, Philippe Labazuy, Mathieu Gouhier, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de météorologie physique (LaMP), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS), and Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE)
Subjects: Eyjafjallajökull eruption, LiDAR, 010504 meteorology & atmospheric sciences, Meteorology, near real time monitoring, [SDE.MCG]Environmental Sciences/Global Changes, plume location maps, Iceland, volcanoes, Management, Monitoring, Policy and Law, 010502 geochemistry & geophysics, 01 natural sciences, remote sensing, Satellite data, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Web application, ash cloud monitoring, Waste Management and Disposal, satellite data, web based reporting, 0105 earth and related environmental sciences, Remote sensing, volcanic crisis, geography, geography.geographical_feature_category, business.industry, Cloud top, plume metrics, cloud top height, mass flux, SEVIRI, Pollution, Plume, Lidar, Volcano, volcanic ash clouds, 13. Climate action, Icelandic volcano, Satellite, business, Geology, Volcanic ash
Abstract: International audience; During the 2010 eruption of Eyjafjallajökull volcano (Iceland) we set up a system designed to ingest satellite data and output volcanic ash cloud products. The system (HVOS = HotVolc Observing System) ingested on-reception data provided every 15 minutes by the SEVIRI sensor flown aboard the Meteosat Second Generation (MSG) satellite. Data were automatically processed and posted on the web to provide plume location maps, as well as to extract plume metrics (cloud top height and mass flux), in near-real time. Given the closing speeds for aircraft approaching such hazardous ash clouds, reporting delays for such products have to be minimised.
Published: 2012
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47. Modeling Eruption Source Parameters by Integrating Field, Ground-Based, and Satellite-Based Measurements: The Case of the 23 February 2013 Etna Paroxysm

Author: Simona Scollo, Antonio Cristaldi, Mathieu Gouhier, Daniele Andronico, Matthieu Poret, Antonio Costa, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Synopsys Inc., Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Istituto Nazionale di Geofisica e Vulcanologia – Sezione di Pisa (INGV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), and Jouhannel, Sylvaine
Subjects: 010504 meteorology & atmospheric sciences, total grain-size distribution, total grain‐size distribution, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Lava, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, PM10, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Tephra, Sea level, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Sampling (statistics), tephra dispersal, Wind direction, SEVIRI, Aerosol, Geophysics, Volcano, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], [SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology, FALL3D, [SDU.STU.GP] Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Satellite, Geology, air traffic safety
Abstract: International audience; Volcanic plumes from Etna volcano (Italy) are governed by easterly winds driving ash over the Ionian Sea. The limited land tephra deposit makes total grain-size distribution (TGSD) assessment and its fine ash fraction highly uncertain. On 23 February 2013, a lava fountain produced a 9-km-high column above sea level (a.s.l.). The atypical north-easterly wind direction dispersed the tephra from Etna to the Puglia region (southern Italy) allowing sampling up to very distal areas. This study uses field measurements to estimate the field-based TGSD. Very fine ash distribution (particle matter below 10 μm—PM10) is explored parameterizing the field-TGSD through a bi-lognormal and bi-Weibull distribution. However, none of the two latter TGSDs allow simulating any far-traveling airborne ash up to distal areas. Accounting for the airborne ash retrieved from satellite (Spinning Enhanced Visible and Infrared Imager), we proposed an empirical modification of the field-based TGSD including very fine ash through a power law decay of the distribution. The input source parameters are inverted by comparing simulations against measurements. Results suggest a column height of 8.7 km a.s.l., a total erupted mass of 4.9 × 109 kg, a PM10 content between 0.4 and 1.3 wt%, and an aggregate fraction of 2 wt% of the fine ash. Aerosol optical depth measurements from the AErosol RObotic NETwork are also used to corroborate the results at 1,700 km from the source. Integrating numerical models with field, ground-based, and satellite-based data aims at providing a better TGSD estimation including very fine ash, crucial for air traffic safety.
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48. Volcano Crisis Management at Piton de la Fournaise (La Réunion) during the COVID-19 Lockdown

Author: Frédéric Lauret, Valérie Ferrazzini, Luciano Garavaglia, Aline Peltier, Nicolas Villeneuve, Andrew J. L. Harris, Lise Retailleau, Michael S. Ramsey, Diego Coppola, Christophe Brunet, Jean-Luc Froger, Santiago Arellano, Fabrice J. Fontaine, Marco Liuzzo, Jacques Lebreton, Lucia Gurioli, Nicolas Desfete, Philippe Catherine, François Beauducel, Patrice Boissier, Sergio Gurrieri, Kevin Canjamale, Cyprien Griot, Andrea Di Muro, Alexis Hrysiewicz, Mathieu Gouhier, Nicole Richter, Philippe Kowalski, Oryaëlle Chevrel, Institut de Physique du Globe de Paris, Observatoire Volcanologique du Piton de la Fournaise (OVPF), Laboratoire GéoSciences Réunion (LGSR), Université de La Réunion (UR)-Institut de Physique du Globe de Paris, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Dipartimento di Scienze della Terra, Università di Torino, Turin, Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), Department of Space, Earth and Environment, Chalmers University of Technology, Chalmers University of Technology [Gothenburg, Sweden], Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Palermo (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Department of Geology and Environmental Science [Pittsburgh], University of Pittsburgh (PITT), Pennsylvania Commonwealth System of Higher Education (PCSHE)-Pennsylvania Commonwealth System of Higher Education (PCSHE), Institut de Physique du Globe de Paris (IPG Paris), Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris), Università degli studi di Torino = University of Turin (UNITO), and ANR-16-CE39-0009,LAVA,Lava et la Ville: l'évaluation des risques, de réduction des risques et de gestion des crises de effusive Désastres(2016)
Subjects: geography, History, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Coronavirus disease 2019 (COVID-19), business.industry, Environmental resource management, Context (language use), Crisis management, 010502 geochemistry & geophysics, 01 natural sciences, World health, Geophysics, Trustworthiness, Volcano, 13. Climate action, Observatory, Global health, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, business, 0105 earth and related environmental sciences
Abstract: In March 2020, the coronavirus disease 2019 outbreak was declared a pandemic by the World Health Organization and became a global health crisis. Authorities worldwide implemented lockdowns to restrict travel and social exchanges in a global effort to counter the pandemic. In France, and in French overseas departments, the lockdown was effective from 17 March to 11 May 2020. It was in this context that the 2–6 April 2020 eruption of Piton de la Fournaise (La Réunion Island, Indian Ocean) took place. Upon the announcement of the lockdown in France, a reduced activity plan was set up by the Institut de Physique du Globe de Paris, which manages the Observatoire Volcanologique du Piton de la Fournaise (OVPF). The aim was to (1) maintain remote monitoring operations by teleworking and (2) authorize fieldwork only for critical reasons, such as serious breakdowns of stations or transmission relays. This eruption provided an opportunity for the observatory to validate its capacity to manage a volcanic crisis with 100% remotely operated monitoring networks. We thus present the long- and short-term precursors to the eruption, and the evolution of the eruption recorded using the real-time monitoring data as communicated to the stakeholders. The data were from both continuously recording and transmitting field instruments as well as satellites. The volcano observatory staff remotely managed the volcano crisis with the various stakeholders based only on these remotely functioning networks. Monitoring duties were also assured in the absence of ad hoc field investigation of the eruption by observatory staff or face-to-face communications. The density and reliability of the OVPF networks, combined with satellite observations, allowed for trustworthy instrument-based monitoring of the eruption and continuity of the OVPF duties in issuing regular updates of volcanic activity in the context of a double crisis: volcanic and health.
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49. Low efficiency of large volcanic eruptions in transporting very fine ash into the atmosphere

Author: Arnaud Guillin, Matthieu Poret, Antonio Costa, Mathieu Deslandes, Nourddine Azzaoui, Mathieu Gouhier, Julia Eychenne, Philippe Husson, Laboratoire Magmas et Volcans (LMV), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), Equipe Probabilités, Analyse et Statistique, Laboratoire de Mathématiques Blaise Pascal (LMBP), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Bologna (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0301 basic medicine, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], lcsh:Medicine, Particle (ecology), Atmospheric sciences, Article, Atmosphere, 03 medical and health sciences, 0302 clinical medicine, Settling, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, lcsh:Science, geography, Multidisciplinary, Explosive eruption, geography.geographical_feature_category, lcsh:R, Sedimentation, Grain size, 030104 developmental biology, Volcano, 13. Climate action, Environmental science, lcsh:Q, 030217 neurology & neurosurgery, Volcanic ash
Abstract: Volcanic ash clouds are common, often unpredictable, phenomena generated during explosive eruptions. Mainly composed of very fine ash particles, they can be transported in the atmosphere at great distances from the source, having detrimental socio-economic impacts. However, proximal settling processes controlling the proportion (ε) of the very fine ash fraction distally transported in the atmosphere are still poorly understood. Yet, for the past two decades, some operational meteorological agencies have used a default value of ε = 5% as input for forecast models of atmospheric ash cloud concentration. Here we show from combined satellite and field data of sustained eruptions that ε actually varies by two orders of magnitude with respect to the mass eruption rate. Unexpectedly, we demonstrate that the most intense eruptions are in fact the least efficient (with ε = 0.1%) in transporting very fine ash through the atmosphere. This implies that the amount of very fine ash distally transported in the atmosphere is up to 50 times lower than previously anticipated. We explain this finding by the efficiency of collective particle settling in ash-rich clouds which enhance early and en masse fallout of very fine ash. This suggests that proximal sedimentation during powerful eruptions is more controlled by the concentration of ash than by the grain size. This has major consequences for decision-makers in charge of air traffic safety regulation, as well as for the understanding of proximal settling processes. Finally, we propose a new statistical model for predicting the source mass eruption rate with an unprecedentedly low level of uncertainty.
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