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Mineral dust produced by wind erosion of arid and semi-arid surfaces is a major component of atmospheric aerosol that affects climate, weather, ecosystems, and socio-economic sectors such as human health, transportation, solar energy, and air quality. Understanding these effects and ultimately improving the resilience of affected countries requires a reliable, dense, and diverse set of dust observations, fundamental for the development and the provision of skillful dust forecasts tailored products. The last decade has seen a notable improvement of dust observational capabilities in terms of considered parameters, geographical coverage, and delivery times, as well as of tailored products of interest to both the scientific community and the various end-users. Given this progress, here we review the current state of observational capabilities including in-situ, ground-based and satellite remote sensing observations, in Northern Africa, the Middle East and Europe for the provision of dust information considering the needs of various users. We also critically discuss observational gaps and related unresolved questions while providing suggestions for overcoming the current limitations. Our review aims to be a milestone for discussing dust observational gaps at a global level to address the needs of users, from research communities to nonscientific stakeholders, Authors acknowledge dr Sangboom Ryoo of Korean Meteorological Administration in Seoul for his help and support.The research leading to these results has received funding from the COST ActionCA16202, supported by COST Association (European Cooperation in Science and Technology), from DustClim Project as part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union (Grant 690462) and by the European Union’s Horizon 2020 research program for societal challenges – smart, green and integrated transport under grant agreement no.723986 (project EUNADICS-AV – European Natural Disaster Coordination and Information System for Aviation). L. Mona acknowledges the ACTRIS-IMP (Implementation project), funded by the European Union’s Horizon 2020 research and innovation programme (Grant no 871115) and the contribution of the ACTRIS-ITALIA JRU (CNR prot. n. 0067310/2017). S. Basart acknowledges CAMS-84 and CAMS2-82 (part of the Copernicus Atmospheric Monitoring Services, CAMS) and the Spanish Jose Castillejo mobility programme (CAS18/0033). V. Amiridis acknowledges support from the European Research Council (grant no. 725698, D-TECT). A. Gkikas acknowledges support by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “2nd Call for H.F.R.I. Research Projects to support Post-Doctoral Researchers” (project acronym: ATLANTAS, project number: 544). S. Kazadzis acknowledges the ACTRIS-CH (Aerosol, Clouds and Trace Gases Research Infrastructure–- Swiss contribution) funded by the State Secretariat for Education, Research, and Innovation, Switzerland. Work of P. Dagsson-Waldhauserova was partly funded by the Czech Science Foundation (HLD-CHANGE project, no. 20-06168Y). C. Pérez García-Pando acknowledges the long-term support from the AXA Research Fund, as well as the support received through the Ramón y Cajal programme (grant RYC-2015-18690) of the Spanish Min, Peer Reviewed, "Article signat per 26 autors/es: Lucia Mona, Vassilis Amiridis, Emilio Cuevas, Antonis Gkikas, Serena Trippetta, Sophie Vandenbussche, Angela Benedetti, Pavla Dagsson-Waldhauserova, Paola Formenti, Alexander Haefele, Stelios Kazadzis, Peter Knippertz, Benoit Laurent, Fabio Madonna, Slobodan Nickovic, Nikolaos Papagiannopoulos, Gelsomina Pappalardo, Carlos Pérez García-Pando, Thomas Popp, Sergio Rodríguez, Andrea Sealy, Nobuo Sugimoto, Enric Terradellas, Ana Vukovic Vimic, Bernadette Weinzierl, and Sara Basart ", Postprint (author's final draft)

Mineral dust produced by wind erosion of arid and semi-arid surfaces is a major component of atmospheric aerosol that affects climate, weather, ecosystems, and socio-economic sectors such as human health, transportation, solar energy, and air quality. Understanding these effects and ultimately improving the resilience of affected countries requires a reliable, dense, and diverse set of dust observations, fundamental for the development and the provision of skillful dust forecasts tailored products. The last decade has seen a notable improvement of dust observational capabilities in terms of considered parameters, geographical coverage, and delivery times, as well as of tailored products of interest to both the scientific community and the various end-users. Given this progress, here we review the current state of observational capabilities including in-situ, ground-based and satellite remote sensing observations, in Northern Africa, the Middle East and Europe for the provision of dust information considering the needs of various users. We also critically discuss observational gaps and related unresolved questions while providing suggestions for overcoming the current limitations. Our review aims to be a milestone for discussing dust observational gaps at a global level to address the needs of users, from research communities to non-scientific stakeholders.

Durante la erupción del volcán de Cumbre Vieja, en la isla de La Palma en 2021, la Agencia Estatal de Meteorología (AEMET), en calidad de Servicio Nacional y Autoridad Meteorológica del Estado, prestó diferentes servicios de apoyo al Comité Científico y al Comité Asesor del Plan de Emergencias Volcánicas de Canarias (PEVOLCA). Parte de sus actividades abarcaron la vigilancia y predicción meteorológica, la monitorización y predicción del transporte del penacho volcánico, y la valoración del impacto de las emisiones de gases y cenizas de la erupción volcánica en la calidad del aire en la isla de La Palma y en la región de Canarias.

Recent studies have found increases in the cardiovascular mortality rates during poor air quality events due to outbreaks of desert dust. In Tenerife, we collected (2014–2017) data in 829 patients admitted with a heart failure diagnosis in the Emergency Department of the University Hospital of the Canaries. In this region, concentrations of PM10 and PM2.5 are usually low (~20 and 10 µg/m3), but they increase to 360 and 115 μg/m3, respectively, during Saharan dust events. By using statistical tools (including multivariable logistic regressions), we compared in-hospital mortality of patients with heart failure and exposure to PM10 and PM2.5 during dust and no-dust events. We found that 86% of in-hospital heart failure mortality cases occurred during Saharan dust episodes that resulted in PM10 > 50 µg/m3 (interquartile range: 71–96 µg/m3). A multivariate analysis showed that, after adjusting for other covariates, exposure to Saharan dust events associated with PM10 > 50 µg/m3 was an independent predictor of heart failure in-hospital mortality (OR = 2.79, 95% CI (1.066–7.332), p = 0.03). In conclusion, this study demonstrates that exposure to high Saharan dust concentrations is independently associated with in-hospital mortality in patients with heart failure., The Regional Centre for Northern Africa–Middle East–Europe of the WMO SDS-WAS (https://sds-was.aemet.es/) is funded by AEMET and the Barcelona Supercomputing Center (BSC). Part of this study was performed within the frame of VARDUST-SAL (PGC2018-099166-B-I00, funded by the Research State Agency of Spain and the European Regional Development Fund). S. Basart acknowledges the AXA Research Fund for funding the aerosol research at the Barcelona Supercomputing Center (BSC). inDust (COST Action CA16202) is also gratefully acknowledged., Peer Reviewed, Postprint (published version)

Recent studies have found increases in the cardiovascular mortality rates during poor air quality events due to outbreaks of desert dust. In Tenerife, we collected (2014–2017) data in 829 patients admitted with a heart failure diagnosis in the Emergency Department of the University Hospital of the Canaries. In this region, concentrations of PM10 and PM2.5 are usually low (~20 and 10 g/m3), but they increase to 360 and 115 g/m3, respectively, during Saharan dust events. By using statistical tools (including multivariable logistic regressions), we compared in-hospital mortality of patients with heart failure and exposure to PM10 and PM2.5 during dust and no-dust events. We found that 86% of in-hospital heart failure mortality cases occurred during Saharan dust episodes that resulted in PM10 > 50 g/m3 (interquartile range: 71–96 g/m3). A multivariate analysis showed that, after adjusting for other covariates, exposure to Saharan dust events associated with PM10 > 50 g/m3 was an independent predictor of heart failure in-hospital mortality (OR = 2.79, 95% CI (1.066–7.332), p = 0.03). In conclusion, this study demonstrates that exposure to high Saharan dust concentrations is independently associated with in-hospital mortality in patients with heart failure.

This study considers the role of distance to the African source on the amount of deposition. To this end, dry and wet deposition was measured at a site close to Africa (Santa Cruz de Tenerife in the Canary Islands, SCO) and at a distant site located in NE Spain (La Castanya, Montseny, MSY). Because of the important influence of African influence on the buildup of particles in the atmosphere, we specifically addressed the contribution of North African events (NAF events) compared to other provenances (no-NAF events) in the wet and dry pathways at the two sites. At the site close to Africa, most of the crustal-derived elements were deposited in the dry mode, with NAF events contributing more than no-NAF events. Marine elements, by contrast, were mostly deposited at this site in the wet form with a predominance of no-NAF events. At MSY, wet deposition of SO4–S, NO3–N and NH4–N during NAF events was higher than at the site close to Africa, either in the wet or dry mode. This fact suggests that mineral dust interacts with pollutants, the mineral surface being coated with ammonium, sulphate and nitrate ions as the dust plume encounters polluted air masses in its way from North Africa to the Western Mediterranean. African dust may provide a mechanism of pollution scavenging and our results indicate that this removal is more effective in the wet mode at sites far away from the mineral source.

This paper presents a new empirical equation relating horizontal visibility and PM10 dust concentrations. The new empirical equation (IZO-Eq) is derived from observations performed at the Izana Atmospheric Observatory (IZO, 28.30 degrees N, 16.49 degrees W, 2367 m a.s.l., Tenerife, Spain), recorded during Saharan dust outbreaks from 2003 to 2010. A filter based on relative humidity, present-weather and aerosol optical properties is applied to identify dust events. IZO-Eq is validated in the Sahel region during the dry and wet seasons (2006-2008) using data from two PM10 monitoring stations from the African Monsoon Multidisciplinary Analysis (AMMA) International Project, and data from the nearest meteorological synoptic stations. The estimated PM10, derived from IZO-Eq is compared against that those obtained by other empirical equations and dust surface concentrations from NMMB/BSC-Dust model. IZO-Eq presents better performance than the other equations in both dry and wet seasons when compared with observed PM10 at two Sahelian sites. IZO-Eq is also able to reproduce the surface concentration variability simulated by NMMB/BSC-Dust. Above 10 km of horizontal visibility, empirical equations cannot be used to estimate PM10, since above this threshold equations estimate a nearly constant PM10 value, regardless of the visibility range. A comparison between the PM10 spatial distributions derived from visibility SYNOP observations through IZO-Eq, the modelled values from the NMMB/BSC-Dust model and aerosol optical depth (AOD) retrieved from MODIS is performed for the 2006-2008 period. The different spatial distributions present a rather good agreement among them as well as to reproduce the characteristic seasonal dust features over North Africa., Postprint (published version)

In the present work, atmospheric mineral dust from a MACC-II short reanalysis run for 2 years (2007-2008) has been evaluated over northern Africa and the Middle East using satellite aerosol products (from MISR, MODIS and OMI satellite sensors), ground-based AERONET data, in situ PM10 concentrations from AMMA, and extinction vertical profiles from two ground-based lidars and CALIOP satellite-based lidar. The MACC-II aerosol optical depth (AOD) spatial and temporal (seasonal and interannual) variability shows good agreement with those provided by satellite sensors. The capability of the model to reproduce the AOD, Angstrom exponent (AE) and dust optical depth (DOD) from daily to seasonal time-scale is quantified over 26 AERONET stations located in eight geographically distinct regions by using statistical parameters. Overall DOD seasonal variation is fairly well simulated by MACC-II in all regions, although the correlation is significantly higher in dust transport regions than in dust source regions. The ability of MACC-II in reproducing dust vertical profiles has been assessed by comparing seasonal averaged extinction vertical profiles simulated by MACC-II under dust conditions with corresponding extinction profiles obtained with lidar instruments at M'Bour and Santa Cruz de Tenerife, and with CALIOP. We find a good agreement in dust layers structures and averaged extinction vertical profiles between MACC-II, the lidars and CALIOP above the marine boundary layer from 1 to 6 km. Surface dust daily mean concentrations from MACC-II reanalysis has been evaluated with daily averaged PM10 at three monitoring stations of the Sahelian Dust Transect. MACC-II correctly reproduces daily to interannual surface dust concentration variability, although it underestimates daily and monthly means all year long, especially in winter and early spring (dry season). MACC-II reproduces well the dust variability recorded along the station transect which reflects the variability in dust emi, Postprint (published version)

Epidemics of meningococcal meningitis are concentrated in sub-Saharan Africa during the dry season, a period when the region is affected by the Harmattan, a dry and dusty northeasterly trade wind blowing from the Sahara into the Gulf of Guinea.

Peer Reviewed

El polvo mineral atmosférico desempeña un papel muy importante en la atmósfera por su interacción con el balance radiativo y con la microfísica de nubes. África Septentrional es la mayor fuente de polvo mineral en el mundo. Sin embargo, carece de sistemas de observación desde tierra adecuados y la información desde satélite es muy limitada debido a la alta reflectividad del suelo. Por ello, se valora la posibilidad de usar la visibilidad horizontal observada en las estaciones meteorológicas como una forma indirecta de estimar el contenido de polvo en la atmósfera al nivel de la superficie. En este trabajo se utilizan observaciones de visibilidad para analizar la distribución geográfica de polvo mineral en África Septentrional y Oriente Medio, así como su variabilidad estacional. Posteriormente, se estudia la relación entre visibilidad y la concentración de partículas y se halla una relación empírica entre ambas magnitudes que es comparada con otras relaciones similares deducidas por otros autores., Postprint (published version)

Cuando el viento es moderado o fuerte, puede levantar grandes masas de polvo y arena procedentes de suelos secos y desnudos e incorporarlas a la circulación atmosférica. Las partículas de menor tamaño pueden viajar durante varios días hasta distancias de centenares o millares de kilómetros antes de ser depositadas nuevamente sobre el suelo. Para países situados en zonas áridas o a sotavento de las mismas, el polvo atmosférico supone una grave amenaza para el medio ambiente, la salud humana y la economía. Además, la interacción del polvo con procesos atmosféricos como la radiación o la microfísica de nubes hace imprescindible su incorporación tanto a los modelos climáticos como a los de predicción numérica del tiempo., Postprint (published version)

The BSC-DREAM8b model and its predecessor are analysed in terms of aerosol optical depth (AOD) for 2004 over Northern Africa, the Mediterranean and the Middle East. We discuss the model performance and we test and analyse its behaviour with new components. The results are evaluated using hourly data from 44 AERONET stations and seasonally averaged satellite observations. The operational versions strongly underestimate the winter AOD over the Sahel and overestimate the AOD over the Middle East and the Mediterranean achieving a low average annual correlation (~0.35). The use of a more detailed size distribution and a corrected wash-out ratio, together with a new dry deposition scheme, improves the transport over the Mediterranean, although underestimations remain over the Sahel and overestimations over the Middle East. The inclusion of a ‘preferential source’ mask improves the localisation of the main North African sources and consequently the dust transport towards Europe and the Atlantic. The use of a more physically based dust emission scheme and a new soil texture database leads to significant improvements in the representation of emissions and the transport over the Sahel, achieving an average annual correlation of 0.53. In this case, the use of a preferential source mask does not introduce significant improvements, Postprint (published version)

Postprint (published version)

High mineral dust-laden air mass potential source regions affecting the Marine Boundary Layer (MBL) of the Subtropical Eastern North Atlantic Region above 25°N (SENAR), directly or by means of gravitational settlement, were objectively identified. We introduced a new hybrid Lagrangian-Eulerian receptor model, in which air mass residence time probability maps in the geographical domain latitude = [5°N, 60°N], longitude = [70°W, 30°E] were combined with TOMS-AI data (TAPI Index), and with simulated Total Suspended Particles (TSP) with the BSC/DREAM model (SDPI Index). Both approaches show a good agreement. For dust gravitational settlement episodes within the MBL, the dust sources are located in southernmost latitudes compared to those associated with lower air mass transport. A seasonal variability in potential dust sources is found with both approaches, TAPI and SDPI. In winter, most dust sources are located within the Sahara in an area bounded by latitude = [18°N, 35°N], longitude = [15°W, 15°E]. In summer, a high dust-laden air mass reservoir above the Atlantic Ocean has been found during episodes for low altitudes, and dust source regions in the Sahara have been identified for middle and upper altitudes. The Bodelé depression was found to have a minor impact on dust outbreaks affecting the SENAR. © 2011 Elsevier Ltd.

African dust intrusions in the marine mixing layer of the Eastern North Atlantic subtropical region (23.5◦N to 35◦N) are favoured in winter when the eastern edge of the Azores High covers Southwestern Europe and North Africa. In situ ground pressure observations and reanalysis from National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) and European Centre forMedium-RangeWeather Forecasts (ECMWF) indicate that the Azores High has strengthened and shifted eastward in winter over the last three decades. This is evidenced by the increase over time of the Madrid–Tenerife Index which is defined as the geopotential height anomaly difference at 1000 mb between Tenerife (28.5◦N; 16.3◦W) and Madrid (40.5◦N; 3.5◦W) in winter and of the African Index which is defined as the residence time over Africa of air mass trajectories entering the subtropical Eastern North Atlantic Ocean. Barcelona Supercomputing Center/Dust Regional AtmosphericModel (BSC-DREAM) dust regional model simulations from 1958 to 2006 were performed, assuming that the soil characteristics of dust sources remained unchanged over time. Simulated winter dust concentration levels are well correlated (0.67) with the available background observations for the 1998–2004 period. The model results show a two-fold increase in winter dust concentrations over the 1980–2006 period with respect to the 1958–1979 period, corresponding to the strengthening and eastward shift of the Azores High., Postprint (published version)

Postprint (published version)

Emissions of sulphur hexafluoride (SF6), one of the strongest greenhouse gases on a per molecule basis, are targeted to be collectively reduced under the Kyoto Protocol. Because of its long atmospheric lifetime (estimated as 800 to 3200 years), the accumulation of SF6 in the atmosphere is a direct measure of its global emissions. Examination of our extended data set of globally distributed high-precision SF6 observations shows an increase in SF6 abundance from near zero in the 1970s to a global mean of 6.7 ppt by the end of 2008. In-depth evaluation of our long-term data records shows that the global source of SF6 decreased after 1995, most likely due to SF6 emission reductions in industrialised countries, but increased again after 1998. By subtracting those emissions reported by Annex I countries to the United Nations Framework Convention of Climatic Change (UNFCCC) from our observation-inferred SF6 source leaves a surprisingly large gap of more than 70–80% of non-reported SF6 emissions in the last decade. This suggests a strong under-estimation of emissions in Annex I countries and underlines the urgent need for independent atmospheric verification of greenhouse gases emissions accounting.

Emissions of sulphur hexafluoride (SF6), one of the strongest greenhouse gases on a per molecule basis, are targeted to be collectively reduced under the Kyoto Protocol. Because of its long atmospheric lifetime (estimated as 800 to 3200 years), the accumulation of SF6 in the atmosphere is a direct measure of its global emissions. Examination of our extended data set of globally distributed high-precision SF6 observations shows an increase in SF6 abundance from near zero in the 1970s to a global mean of 6.7 ppt by the end of 2008. In-depth evaluation of our long-term data records shows that the global source of SF6 decreased after 1995, most likely due to SF6 emission reductions in industrialised countries, but increased again after 1998. By subtracting those emissions reported by Annex I countries to the United Nations Framework Convention of Climatic Change (UNFCCC) from our observation-inferred SF6 source leaves a surprisingly large gap of more than 70–80% of non-reported SF6 emissions in the last decade. This suggests a strong under-estimation of emissions in Annex I countries and underlines the urgent need for independent atmospheric verification of greenhouse gases emissions accounting.

We proviede an atmospheric aerosol characterization for North Africa, Northeastern Atlantic, Mediterranean and Middle East based on the analysis of quality-assured direct-sun observations of 39 stations of the AErosol RObotic NETwork (AERONET) which include at least an annual cycle within the 1994–2007 period. We extensively test and apply the recently introduced graphical method of Gobbi and co-authors to track and discriminate different aerosol types and quantify the contribution of mineral dust. The method relies on the combined analysis of the Ångström exponent (α) and its spectral curvature δα. Plotting data in these coordinates allows to infer aerosol fine mode radius (Rf) and fractional contribution (η) to total Aerosol Optical Depth (AOD) and separate AOD growth due to fine-mode aerosol humidification and/or coagulation from AOD growth due to the increase in coarse particles or cloud contamination. Our results confirm the robustness of this graphical method. Large mineral dust is found to be the most important constituent in Northern Africa and Middle East. Under specific meteorological conditions, its transport to Southern Europe is observed from spring to autumn and decreasing with latitude. We observe "pure Saharan dust" conditions to show AOD>0.7 (ranging up to 5), α<0.3 and δα<0 corresponding to η<40% and (Rf)~0.13 μm. Small pollution particles are abundant in sites close to urban and industrial areas of Continental and Eastern Europe and Middle East, as well as, important contributions of biomass burning are observed in the sub-Sahel region in winter. These small aerosols are associated to AOD<1, α>1.5 and δα~−0.2 corresponding to η>70% and Rf~0.13 μm. Here, dust mixed with fine pollution aerosols shifts the observations to the region α<0.75, in which the fine mode contribution is less than 40%., Peer Reviewed, Postprint (published version)

Emissions of sulphur hexafluoride (SF6), one of the strongest greenhouse gases on a per molecule basis, are targeted to be collectively reduced under the Kyoto Protocol. Because of its long atmospheric lifetime (≈3000 years), the accumulation of SF6 in the atmosphere is a direct measure of its global emissions. Examination of our extended data set of globally distributed high-precision SF6 observations shows an increase in SF6 abundance from near zero in the 1970s to a global mean of 6.7 ppt by the end of 2008. In-depth evaluation of our long-term data records shows that the global source of SF6 decreased after 1995, most likely due to SF6 emission reductions in industrialised countries, but increased again after 1998. By subtracting those emissions reported by Annex I countries to the United Nations Framework Convention of Climatic Change (UNFCCC) from our observation-inferred SF6 source leaves a surprisingly large gap of more than 70–80% of non-reported SF6 emissions in the last decade.

Emissions of sulphur hexafluoride (SF6), one of the strongest greenhouse gases on a per molecule basis, are targeted to be collectively reduced under the Kyoto Protocol. Because of its long atmospheric lifetime (≈3000 years), the accumulation of SF6 in the atmosphere is a direct measure of its global emissions. Examination of our extended data set of globally distributed high-precision SF6 observations shows an increase in SF6 abundance from near zero in the 1970s to a global mean of 6.7 ppt by the end of 2008. In-depth evaluation of our long-term data records shows that the global source of SF6 decreased after 1995, most likely due to SF6 emission reductions in industrialised countries, but increased again after 1998. By subtracting those emissions reported by Annex I countries to the United Nations Framework Convention of Climatic Change (UNFCCC) from our observation-inferred SF6 source leaves a surprisingly large gap of more than 70–80% of non-reported SF6 emissions in the last decade.

Surface soil samples from various altitudes on Tenerife Island, ranging from sea level up to 3400 m above mean sea level, were analyzed to study the distribution of 26 polycyclic aromatic hydrocarbons (PAHs) in a remote subtropical area. The stable atmospheric conditions in this island define three vertically stratified layers: marine boundary, trade-wind inversion, and free troposphere. Total PAH concentrations, 1.9 to 6000 µg/kg dry wt., were high when compared with those in tropical areas and in a similar range to those in temperate areas. In the marine boundary layer, fluoranthene (Fla), pyrene (Pyr), benz[a]anthracene (BaA), and chrysene (C + T) were largely dominant. The predominance of Fla over Pyr may reflect photo-oxidative processes during atmospheric transport, although coal combustion inputs cannot be excluded. The PAHs found in higher concentration in the soils from the inversion layer were benzo[b + j]fluoranthene (BbjF) + benzo[k]fluoranthene (BkF) > benzo[e]pyrene (BeP) {approx} indeno[1,2,3-cd]pyrene (Ind) > benzo[a]pyrene (BaP) {cong} benzo[ghi]perylene (Bghi) > coronene (Cor) {cong} dibenz[a,h]anthracene (Dib), reflecting that high temperatures and insolation prevent the accumulation of PAHs more volatile than BbjF in significant amounts. These climatic conditions involve a process of standardization that prevents the identification of specific PAH sources such as traffic, forest fires, or industrial inputs. Only soils with high total organic carbon (TOC) (e.g., 10–30%) preserve the more volatile compounds such as phenanthrene (Phe), methylphenanthrenes (MPhe), dimethylphenanthrenes (DMPhe), and retene (Ret). However, no relation between PAHs and soil TOC and black carbon (BC) was found. The specific PAH distributions of the free tropospheric region suggest a direct input from pyrolytic processes related to the volcanic emission of gases in Teide.