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4. Impact of subsurface crevassing on the depth–age relationship of high-Alpine ice cores extracted at Col du Dôme between 1994 and 2012.

Author

Preunkert, Susanne, Bohleber, Pascal, Legrand, Michel, Gilbert, Adrien, Erhardt, Tobias, Purtschert, Roland, Zipf, Lars, Waldner, Astrid, McConnell, Joseph R., and Fischer, Hubertus

Subjects
*ICE cores, *CORE drilling, *ALPINE glaciers, *BEDROCK, *SEA level, *TWENTIETH century
Abstract

Three seasonally resolved ice core records covering the 20th century were extracted in 1994, 2004, and 2012 at a nearly identical location from the Col du Dôme (4250 m above sea level, m a.s.l.; Mont Blanc, French Alps) drill site. Here, we complete and combine chemical records of major ions and radiometric measurements of 3 H and 210 Pb obtained from these three cores with a 3D ice flow model of the Col du Dôme glacier to investigate in detail the origin of discontinuities observed in the depth–age relation of the ice cores drilled in 2004 and 2012. Taking advantage of the granitic bedrock at Col du Dôme, which makes the ice core 210 Pb records sensitive to the presence of upstream crevasses, and the fact that the depth–age disturbances are observed at depths for which absolute time markers are available, we draw an overall picture of a dynamic crevasse formation. This can explain the non-disturbed depth–age relation of the ice core drilled in 1994 and the perturbations observed in those drilled in 2004 and 2012. Since crevasses are common at high-Alpine glacier sites, our study points to the important need for rigorous investigations of the depth–age scale and glaciological conditions upstream of drill sites before interpreting high-alpine ice core records in terms of atmospheric changes. [ABSTRACT FROM AUTHOR]

Published
2024
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5. 20th Century Changes of DOC and Its 14C Signature Archived in Caucasus Ice‐Core: Implications for Past Sources of Organic Carbon Aerosol in South‐Eastern Europe.

Author

Legrand, Michel, Preunkert, Susanne, Kutuzov, Stanislav, Siour, Guillaume, Mikhalenko, Vladimir, Dolgova, Ekaterina, and Friedrich, Ronny

Subjects
AEROSOLS, TWENTIETH century, ICE cores, CORE drilling, GLOBAL warming
Abstract

To reconstruct the history of organic carbon (OC) aerosol over south‐eastern Europe, dissolved organic carbon (DOC) and its 14C signature (DO14C) were investigated along an ice core drilled at the Mount Elbrus (ELB) in Caucasus. In summer, compared to pre‐1945 levels, the DOC concentrations increased by 45% after 1960, the mean DO14C depletion in recent ELB ice relative to atmospheric 14CO2 of 32% being attributed to fossil‐fuel sources. DO14C content of ice deposited during the bomb‐peak era (1955–1980) closely followed atmospheric 14CO2 changes caused by atmospheric nuclear tests, suggesting the living biosphere as the main biogenic source of DOC in summer in this region. ELB data contrast with those previously obtained in summer Alpine (western Europe) ice in which a post‐1950 doubling of DOC was observed and attributed to enhanced emissions of organic compounds from vegetation in France. This regional difference is discussed with respect to changes of biogenic organic compound emissions in response to past change of use‐land and global warming. ELB data document, for the first time, changes of DOC and DO14C in winter mountain ice showing an increase by 44% of DOC levels associated with a 14C signature being 47% lower than that of atmospheric 14CO2 in ELB ice deposited after 1960. The 14C winter ELB ice record followed atmospheric 14CO2 changes with a delay of ∼3 years, suggesting that remaining emissions from the living biosphere, together with a small contribution from wood burning, are the main biogenic sources of DOC in winter in this region. Plain Language Summary: A good knowledge of past aerosol load and composition is important for climate change. In addition to sulfate, organic carbon aerosol (OC) is a major constituent of present‐day aerosol but its budget remains far less understood. Ice‐core chemical studies help to quantify natural versus anthropogenic sources over the past. Previous investigations of OC and its radiocarbon signature in Alpine ice had shown a doubling of summer OC due to enhanced emissions from vegetation contrasting with a weak impact of fossil‐fuel emissions in western Europe. The regional character of biogenic emissions motivated, however, further studies conducted in other regions. Investigations of OC and its radiocarbon signature in an ice core extracted in the Caucasus permitted to reconstruct past OC changes in the south‐eastern Europe. It is shown that, even in 1970, vegetation emissions still dominate fossil‐fuel emissions as source of OC in summer. A quite large temporal variability of OC is observed and attributed to variations of vegetation emissions in response to past fluctuations of summer temperature in this region. After 1960, fossil‐fuel emissions in winter became almost as large as biogenic emissions that were related to the living biosphere with a small contribution from wood burning at that season. Key Points: Biogenic sources dominate fossil‐fuel sources of present‐day summer organic carbon aerosol (70% vs. 30%) in south‐eastern EuropeLarge pre‐industrial variability of organic carbon aerosol in summer driven by vegetation emissions modulated by past temperaturesLiving biosphere with a small contribution from wood burning slightly exceeds present‐day fossil‐fuel sources of organic carbon in winter [ABSTRACT FROM AUTHOR]

Published
2024
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10. Accumulation rates over the past 260 years archived in Elbrus ice core, Caucasus.

Author

Mikhalenko, Vladimir, Kutuzov, Stanislav, Toropov, Pavel, Legrand, Michel, Sokratov, Sergey, Chernyakov, Gleb, Lavrentiev, Ivan, Preunkert, Susanne, Kozachek, Anna, Vorobiev, Mstislav, Khairedinova, Aleksandra, and Lipenkov, Vladimir

Subjects
ICE cores, PRECIPITATION anomalies, NORTH Atlantic oscillation, PRECIPITATION variability, PRECIPITATION gauges
Abstract

In this study, we present a seasonally resolved accumulation record spanning from 1750 to 2009 Common Era (CE), based on a 181.8 m ice core obtained from the Elbrus Western Plateau in the Caucasus. We implemented various methods to account for uncertainties associated with glacier flow, layer thinning, and dating. Additionally, we applied a novel approach to calculate a seasonal calendar for meteorological data, enabling comparison with ice core records. The reconstructed accumulation data were compared with available meteorological data, gridded precipitation records, and paleo-reanalysis data. Reconstructed accumulation is representative for a large region south of the Eastern European plain and Black Sea region with summer precipitation being the primary driver of precipitation variability. We identified a statistically significant relationship between changes in regional precipitation and fluctuations in the North Atlantic Oscillation (NAO) index, which is, however, not stable over the entire period covered by the ice core. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Supplementary material to "Impact of subsurface crevassing on the depth-age relationship of high-alpine ice cores extracted at Col du Dôme between 1994 and 2012"

Author

Preunkert, Susanne, primary, Bohleber, Pascal, additional, Legrand, Michel, additional, Fischer, Hubertus, additional, Gilbert, Adrien, additional, Erhardt, Tobias, additional, Purtschert, Roland, additional, Zipf, Lars, additional, Waldner, Astrid, additional, and McConnell, Joseph R., additional

Published
2023
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17. Accumulation rates over the past 260 years archived in Elbrus ice core, Caucasus.

Author

Mikhalenko, Vladimir, Kutuzov, Stanislav, Toropov, Pavel, Legrand, Michel, Sokratov, Sergey, Chernyakov, Gleb, Lavrentiev, Ivan, Preunkert, Susanne, Kozachek, Anna, Vorobiev, Mstislav, Khairedinova, Aleksandra, and Lipenkov, Vladimir

Abstract

In this study, we present a seasonal-resolution accumulation record spanning the period from 1750 to 2009 Common Era (CE), based on a 181.8-m ice core obtained from the Elbrus Western Plateau in the Caucasus. We implemented various methods to account for uncertainties associated with glacier flow, layer thinning, and dating. Additionally, we developed a novel approach to calculate a seasonal calendar for meteorological data, enabling comparison with ice core records. The reconstructed accumulation data were compared with available meteorological data, gridded precipitation records, and paleo reanalysis data. Reconstructed accumulation is representative for a large region south of Eastern European plain and Black sea region. Summer precipitation was found to be the primary driver of precipitation variability. We identified a statistically significant but unstable in time relationship between changes in precipitation in the region and fluctuations of the North Atlantic Oscillation (NAO) index. [ABSTRACT FROM AUTHOR]

Published
2023
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20. Changes of ammonia and nitrogen oxide emissions in South-eastern Europe inferred from an Elbrus (Caucasus, Russia) ice core record (1774-2009 CE)

Author

Legrand, Michel, primary, Vorobyev, Mstislav, additional, Bokuchava, Daria, additional, Khairedinova, Aleksandra, additional, Kutuzov, Stanislav, additional, Mikhalenko, Vladimir, additional, Vinogradova, Maria, additional, Plach, Andreas, additional, Stohl, Andreas, additional, Ginot, Patrick, additional, Eckhardt, Sabine, additional, and Preunkert, Susanne, additional

Published
2022
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22. Impact of subsurface crevassing on the depth-age relationship of high-alpine ice cores extracted at Col du Dôme between 1994 and 2012.

Author

Preunkert, Susanne, Bohleber, Pascal, Legrand, Michel, Fischer, Hubertus, Gilbert, Adrien, Erhardt, Tobias, Purtschert, Roland, Zipf, Lars, Waldner, Astrid, and McConnell, Joseph R.

Abstract

Three seasonally-resolved ice-core records covering the 20th century were extracted in 1994, 2004 and 2012 at a nearly identical location at the Col du Dôme (4250 m above sea level, m asl, Mont Blanc, French Alps) drill site. Here we complete and combine chemical records of major ions and radiometric measurements of ³H and 210Pb obtained on these three cores together with a 3D ice flow model of the Col du Dôme glacier, to investigate in detail the origin of the discontinuities observed 25 in the depth-age relation of the ice cores drilled in 2004 and 2012. Taking advantage of the granitic bedrock at Col du Dôme, which makes the 210Pb ice-core records sensitive to the presence of upstream crevasses, and the fact that the depth-age disturbances are observed at depths for which absolute time markers were available, we draw an overall picture of a dynamic crevasse formation which can explain the non-disturbed depth-age relation of the ice core drilled in 1994 as well as the perturbations observed in those drilled in 2004 and 2012. Since crevasses are common at high alpine glacier sites, our study 30 points out the mandatory need of rigorous investigations of the depth-age scale before using high alpine sites to interpret atmospheric changes. [ABSTRACT FROM AUTHOR]

Published
2023
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24. RADIOCARBON IN GLOBAL TROPOSPHERIC CARBON DIOXIDE.

Author

Levin, Ingeborg, Hammer, Samuel, Kromer, Bernd, Preunkert, Susanne, Weller, Rolf, and Worthy, Douglas E

Subjects
TROPOSPHERIC aerosols, CARBON dioxide, CARBON isotopes, CARBON cycle, TROPOSPHERIC ozone
Abstract

Since the 1950s, observations of radiocarbon (14C) in tropospheric carbon dioxide (CO2) have been conducted in both hemispheres, documenting the so-called nuclear "bomb spike" and its transfer into the oceans and the terrestrial biosphere, the two compartments permanently exchanging carbon with the atmosphere. Results from the Heidelberg global network of Δ14C-CO2 observations are revisited here with respect to the insights and quantitative constraints they provided on these carbon exchange fluxes. The recent development of global and hemispheric trends of Δ14C-CO2 are further discussed in regard to their suitability to continue providing constraints for 14C-free fossil CO2 emission changes on the global and regional scale. [ABSTRACT FROM AUTHOR]

Published
2022
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26. Ammonium in Antarctic aerosol: Marine biological activity versus long-range transport of biomass burning

Author

Legrand, Michel, Weller, Rolf, Preunkert, Susanne, Jourdain, B., Legrand, Michel, Weller, Rolf, Preunkert, Susanne, and Jourdain, B.

Abstract

Year-round records of the ionic composition of Antarctic aerosol were obtained at the inland Dome C (DC) and coastal Neumayer (NM) sites, with additional observations of black carbon at NM. Discussions focus on the origin of ammonium in Antarctica. This first Antarctic atmospheric study of several species emitted by biomass burning indicates that black carbon, oxalate, and fine potassium reach a maximum in October in relation to biomass burning activity in the southern hemisphere. Ammonium reaches a maximum two months later, suggesting that biomass burning remains a minor ammonium source there. The ammonium maximum in December coincides with the occurrence of diatom blooms in the austral ocean, suggesting that oceanic ammonia emissions are the main source of ammonium in Antarctica. The ammonium to sulfur-derived biogenic species molar ratio of 0.15 in summer suggests far lower ammonia emissions from the Antarctic oceans than mid-latitude southern oceans.

Published
2021

27. Radiocarbon in global tropospheric carbon dioxide

Author

Levin, Ingeborg, Hammer, Samuel, Kromer, Bernd, Preunkert, Susanne, Weller, Rolf, Worthy, Douglas E., Levin, Ingeborg, Hammer, Samuel, Kromer, Bernd, Preunkert, Susanne, Weller, Rolf, and Worthy, Douglas E.

Abstract

Since the 1950s, observations of radiocarbon (14C) in tropospheric carbon dioxide (CO2) have been conducted in both hemispheres, documenting the so-called nuclear "bomb spike" and its transfer into the oceans and the terrestrial biosphere, the two compartments permanently exchanging carbon with the atmosphere. Results from the Heidelberg global network of 14C-CO2 observations are revisited here with respect to the insights and quantitative constraints they provided on these carbon exchange fluxes. The recent development of global and hemispheric trends of 14C-CO2 are further discussed in regard to their suitability to continue providing constraints for 14C-free fossil CO2 emission changes on the global and regional scale.

Published
2021

28. Regional characteristics of atmospheric sulfate formation in East Antarctica imprinted on 17O-excess signature

Author

Ishino, Sakiko, primary, Hattori, Shohei, additional, Legrand, Michel, additional, Chen, Qianjie, additional, Alexander, Becky, additional, Shao, Jingyuan, additional, Huang, Jiayue, additional, Jaegle, Lyatt, additional, Jourdain, Bruno, additional, Preunkert, Susanne, additional, Yamada, Akinori, additional, Yoshida, Naohiro, additional, and Joel, Savarino, additional

Published
2021
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30. What can we learn from ice collected in high mountain rockfall scars? Three examples from the Mont Blanc massif (France)

Author

Ravanel, Ludovic, Magnin, Florence, Guillet, Grégoire, Montagnat, Maurine, Preunkert, Susanne, Duvillard, P.A, Deline, Philip, Pallandre, François, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut de gestion des entreprises -USJ (IGE), Université Saint-Joseph de Beyrouth (USJ), Institut des Géosciences de l’Environnement (IGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Recherche pour le Développement (IRD)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Ecole nationale de ski et d'alpinisme, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), and Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[SDE.MCG]Environmental Sciences/Global Changes, [SDE]Environmental Sciences, [SDE.ES]Environmental Sciences/Environmental and Society, ComputingMilieux_MISCELLANEOUS
Abstract

International audience; The study of the ice (cryostructures, cryostratigraphy, types and age) that partly fills the fractures in rockwall permafrost is necessary to better understand the increasing frequency/volume of rockfalls in the high alpine rockwalls. Typically inaccessible, this ice is visible only when a rockfall occurs, exposing previously hidden ice. Over the past two years, the two largest rockfalls of the decade in the Mont Blanc massif and a smaller one allowed to start the documentation of the rockwall permafrost ice. This poster aims to present the three cases. Up to now, dating has been carried out for only one of the three cases. How to date permafrost ice? Dating ice cores from alpine glaciers has shown the wide time span covered by these, from a few decades to several thousand years. Several dating methods are available to quantify the age. Counting the annual layers, which proved to be effective, is widely used in the study of mountain glaciers but cannot be used for the internal ice of the permafrost since it does not present these annual layers. Structure of the ice in the scar of the Trident of Tacul rockfall scar shows nevertheless a series of layers. We will therefore use radionuclide dating to obtain the absolute age of the ice. So far, only one age is available for interstitial ice from permafrost-affected rockwall: the ice sampled from a felt block that is part of the deposit of the 150'000 m 3 rockfall that occurred in Feb. 2014 at Piz Kesch (Swiss Alps

Published
2019

35. Investigation of a cold-based ice apron on a high-mountain permafrost rock wall using ice texture analysis and micro-14C dating: a case study of the Triangle du Tacul ice apron (Mont Blanc massif, France).

Author

Guillet, Grégoire, Preunkert, Susanne, Ravanel, Ludovic, Montagnat, Maurine, and Friedrich, Ronny

Subjects
PERMAFROST, CORE drilling, COLLOIDAL carbon, GLACIAL Epoch, TRIANGLES, ICE cores
Abstract

The current paper studies the dynamics and age of the Triangle du Tacul (TDT) ice apron, a massive ice volume lying on a steep high-mountain rock wall in the French side of the Mont-Blanc massif at an altitude close to 3640 m a.s.l. Three 60 cm long ice cores were drilled to bedrock (i.e. the rock wall) in 2018 and 2019 at the TDT ice apron. Texture (microstructure and lattice-preferred orientation, LPO) analyses were performed on one core. The two remaining cores were used for radiocarbon dating of the particulate organic carbon fraction (three samples in total). Microstructure and LPO do not substantially vary with along the axis of the ice core. Throughout the core, irregularly shaped grains, associated with strain-induced grain boundary migration and strong single maximum LPO, were observed. Measurements indicate that at the TDT ice deforms under a low strain-rate simple shear regime, with a shear plane parallel to the surface slope of the ice apron. Dynamic recrystallization stands out as the major mechanism for grain growth. Micro-radiocarbon dating indicates that the TDT ice becomes older with depth perpendicular to the ice surface. We observed ice ages older than 600 year BP and at the base of the lowest 30 cm older than 3000 years. [ABSTRACT FROM AUTHOR]

Published
2021
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38. Atmospheric Transport Pathways to Antarctica and the Remote Southern Ocean using Radon-222

Author

Chambers, Scott, Preunkert, Susanne, Weller, Rolf, Hong, Sang-Bum, Humphries, Ruhi S., Tositti, Laura, Angot, Hélène, Legrand, Michel, Williams, Alastair G., Griffiths, Alan D., Crawford, Jagoda, Simmons, Jack, Choi, Taejin, Krummel, Paul B., Molloy, Suzie, Loh, Zoe, Galbally, Ian, Wilson, Stephen, Magand, Olivier, Sprovieri, Frabcesca, Pirrone, Nicola, and Dommergue, Aurélien

Abstract

We discuss remote terrestrial influences on boundary layer air over the Southern Ocean and Antarctica, and the mechanisms by which they arise, using atmospheric radon observations as a proxy. Our primary motivation was to enhance the scientific community’s ability to understand and quantify the potential effects of pollution, nutrient or pollen transport from distant land masses to these remote, sparsely-instrumented regions. Seasonal radon characteristics are discussed at 6 stations (Macquarie Island, King Sejong, Neumayer, Dumont d’Urville, Jang Bogo and Dome Concordia) using 1-4 years of continuous observations. Context is provided for differences observed between these sites by Southern Ocean radon transects between 45-67S made by the Research Vessel Investigator. Synoptic transport of continental air within the marine boundary layer (MBL) dominated radon seasonal cycles in the mid-Southern Ocean site (Macquarie Island). MBL synoptic transport, tropospheric injection, and Antarctic outflow all contributed to the seasonal cycle at the sub-Antarctic site (King Sejong). Tropospheric subsidence and injection events delivered terrestrially-influenced air to the Southern Ocean MBL in the vicinity of the circumpolar trough (or “Polar Front”). Katabatic outflow events from Antarctica were observed to modify trace gas and aerosol characteristics of the MBL 100-200 km off the coast. Radon seasonal cycles at coastal Antarctic sites were dominated by a combination of local radon sources in summer and subsidence of terrestrially-influenced tropospheric air, whereas those on the Antarctic Plateau were primarily controlled by tropospheric subsidence. Separate characterisation of long-term marine and katabatic flow air masses at Dumont d’Urville revealed monthly mean differences in summer of up to 5 ppbv in ozone and 0.3 ng m-3 in gaseous elemental mercury. These differences were largely attributed to chemical processes on the Antarctic Plateau. A comparison of our observations with some Antarctic radon simulations by global climate models over the past two decades indicated that: (i) some models overestimate synoptic transport to Antarctica in the MBL, (ii) the seasonality of the Antarctic ice sheet needs to be better represented in models, (iii) coastal Antarctic radon sources need to be taken into account, and (iv) the underestimation of radon in subsiding tropospheric air needs to be investigated.

Published
2018

44. Characterizing Atmospheric Transport Pathways to Antarctica and the Remote Southern Ocean Using Radon-222

Author

Chambers, Scott D., primary, Preunkert, Susanne, additional, Weller, Rolf, additional, Hong, Sang-Bum, additional, Humphries, Ruhi S., additional, Tositti, Laura, additional, Angot, Hélène, additional, Legrand, Michel, additional, Williams, Alastair G., additional, Griffiths, Alan D., additional, Crawford, Jagoda, additional, Simmons, Jack, additional, Choi, Taejin J., additional, Krummel, Paul B., additional, Molloy, Suzie, additional, Loh, Zoë, additional, Galbally, Ian, additional, Wilson, Stephen, additional, Magand, Olivier, additional, Sprovieri, Francesca, additional, Pirrone, Nicola, additional, and Dommergue, Aurélien, additional

Published
2018
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46. Atmospheric nitrogen oxides (NO and NO2) at Dome C, East Antarctica, during the OPALE campaign

Author

Frey, N. M., Roscoe, H. K., Kukui, Alexandre, Savarino, Joël A., France, J. L., King, M.D., Legrand, Michel, Preunkert, Susanne, British Antarctic Survey (BAS), Natural Environment Research Council (NERC), 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)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), School of Environmental Sciences [Norwich], University of East Anglia [Norwich] (UEA), School of Earth Sciences [Bristol], University of Bristol [Bristol], Université Joseph Fourier - Grenoble 1 (UJF), 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), 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), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:Chemistry, lcsh:QD1-999, [SDE]Environmental Sciences, lcsh:Physics, lcsh:QC1-999
Abstract

Mixing ratios of the atmospheric nitrogen oxides NO and NO2 were measured as part of the OPALE (Oxidant Production in Antarctic Lands & Export) campaign at Dome C, East Antarctica (75.1° S, 123.3° E, 3233 m), during December 2011 to January 2012. Profiles of NOx mixing ratios of the lower 100 m of the atmosphere confirm that, in contrast to the South Pole, air chemistry at Dome C is strongly influenced by large diurnal cycles in solar irradiance and a sudden collapse of the atmospheric boundary layer in the early evening. Depth profiles of mixing ratios in firn air suggest that the upper snowpack at Dome C holds a significant reservoir of photolytically produced NO2 and is a sink of gas-phase ozone (O3). First-time observations of bromine oxide (BrO) at Dome C show that mixing ratios of BrO near the ground are low, certainly less than 5 pptv, with higher levels in the free troposphere. Assuming steady state, observed mixing ratios of BrO and RO2 radicals are too low to explain the large NO2 : NO ratios found in ambient air, possibly indicating the existence of an unknown process contributing to the atmospheric chemistry of reactive nitrogen above the Antarctic Plateau. During 2011–2012, NOx mixing ratios and flux were larger than in 2009–2010, consistent with also larger surface O3 mixing ratios resulting from increased net O3 production. Large NOx mixing ratios at Dome C arise from a combination of continuous sunlight, shallow mixing height and significant NOx emissions by surface snow (FNOx). During 23 December 2011–12 January 2012, median FNOx was twice that during the same period in 2009–2010 due to significantly larger atmospheric turbulence and a slightly stronger snowpack source. A tripling of FNOx in December 2011 was largely due to changes in snowpack source strength caused primarily by changes in NO3− concentrations in the snow skin layer, and only to a secondary order by decrease of total column O3 and associated increase in NO3− photolysis rates. A source of uncertainty in model estimates of FNOx is the quantum yield of NO3− photolysis in natural snow, which may change over time as the snow ages.

Published
2015

47. Size distribution and ionic composition of marine summer aerosol at the continental Antarctic site Kohnen

Author

Weller, Rolf, Legrand, Michel, Preunkert, Susanne, Weller, Rolf, Legrand, Michel, and Preunkert, Susanne

Abstract

We measured aerosol size distributions and conducted bulk as well as size segregated aerosol sampling during two summer campaigns in January 2015 and January 2016 at the continental Antarctic station Kohnen (Dronning Maud Land). Physical and chemical aerosol properties differ conspicuously during the episodic impact of an outstanding low pressure system in 2015 (LPS15) compared to the prevailing clear sky conditions (CSC): The about three days persisting LPS15, located in the eastern Weddell Sea, was associated with marine boundary layer (MBL) air mass intrusion, enhanced condensation particle concentrations (1400±700 cm-3 compared to 250±120 cm-3 during CSC; mean ± SD), occurrence of a new particle formation (NPF) event exhibiting a continuous growth of particle diameters (Dp) from 12 nm to 43 nm over 44 hours (growth rate 0.6 nm h-1), peaking methane sulfonate (MS-), non-sea salt sulfate (nss-SO42-) and Na+ concentrations (190 ng m-3 MS-, 137 ng m-3 nss-SO42-, and 53 ng m-3 Na+ compared to 24±15 ng m-3, 107±20 ng m-3 and 4.1±2.2 ng m-3, respectively, during CSC), and finally an increased MS-/nss-SO42- mass ratio ßMS of 0.4 up to 2.3 (0.21±0.1 during CSC) comparable to typical values found at coastal Antarctic sites. Throughout the observation period a larger part of MS- could be found in super micron aerosol compared to nss-SO42-, i.e. (10±2) % by mass compared to (3.2±2) %, respectively. On the whole, during CSC aged aerosol characterized by an usually mono-modal size distribution around Dp = 60 nm was observed. Although our observations indicate that sporadic impacts of coastal cyclones were associated with enhanced marine aerosol entry, at large aerosol deposition on-site during austral summer should be dominated by the typical steady CSC.

Published
2018

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