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Lorène Julia Marchand, Françoise Hennion, Michèle Tarayre, Marie-Claire Martin, Benoit Renaud Martins, Cécile Monard |
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Title |
Fellfields of the Kerguelen Islands harbour specific soil microbiomes and rhizomicrobiomes of an endemic plant facing necrosis |
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2022 |
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Frontiers in Soil Science |
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2 |
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Polar regions are characterized by rocky terrains with sparse vegetation and oligotrophic soils, i.e. “fellfields”. In such ecosystems, microbial communities should be essential for soil-plant functioning but their diversity is poorly explored. The sub-Antarctic Kerguelen Islands fellfields are characterized by an endemic long-lived cushion plant, Lyallia kerguelensis which rhizosphere may be a shelter for microbes in this harsh environment. Cushions are affected by necrosis and we expect the rhizomicrobiome composition to be related to plant necrosis. We analysed bacterial and fungal communities in bulk- and rhizospheric soils from L. kerguelensis in five different fellfields across the Kerguelen Islands using 16S rRNA and ITS1 metabarcoding. We found that soil microbial communities were composed of both restricted and cosmopolitan taxa. While all sites were dominated by the same bacterial taxa (Chloroflexi, Actinobacteria, α-Proteobacteria and Acidobacteria), the relative abundance of the main fungal phyla (Ascomycota, Basidiomycota, Mortierellomycota and Rozellomycota) highly differed between sites. L. kerguelensis rhizomicrobiome was at least as diverse as the bulk soil, making the rhizosphere a possible reservoir of microbial diversity. It was composed of the same main bacterial phyla than detected in the bulk soil while the composition of the rhizosphere fungal communities was specific to each plant. No common microorganisms were identified regarding cushion necrosis extent across plants and sites, but several microbial putative functions were shared, suggesting a possible shift in soil functioning with cushion necrosis increase. Our study brings new information on the diversity and composition of the microbial communities of fellfield soils in a sub-Antarctic Island and the rhizomicrobiome of a characteristic endemic cushion plant. |
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8492 |
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Lassalle Coralie |
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Title |
Apport des isotopes de l’eau pour comprendre la dynamique climatique et le cycle hydrologique en Terre Adélie |
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Master 2 |
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2022 |
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Dans un contexte de réchauffement climatique, la compréhension de l’évolution passée et future du climat dans le monde représente un enjeu majeur, dans la mesure où la calotte Antarctique peut contribuer à la hausse du niveau marin de près de 60 m. De ce fait, il est important d’appréhender et de documenter la variabilité climatique récente impactant le bilan de masse de surface antarctique, plus spécifiquement dans les régions côtières. Néanmoins, les enregistrements issus des observations instrumentales et satellitaires sont bien trop courts pour faire la distinction entre la variabilité naturelle du signal climatique et l’impact anthropique. D’où le lancement du raid scientifique ASUMA (« Improving the Accurancy of SUrface Mass balance of Antarctica »), dans le cadre de l’ANR (« Agence Nationale de la Recherche »), en Terre Adélie, zone côtière à fort taux d’accumulation caractérisée par la présence de vents catabatiques, afin de mieux connaitre l’évolution actuelle du bilan de masse. Un volet du projet est d’analyser la composition isotopique des carottes de névé dans l’objectif de fournir des informations sur le cycle hydrologique atmosphérique et la dynamique climatique. D’ailleurs, Sentia GOURSAUD (2018) montre que, dans la région côtière de Terre Adélie, la composition isotopique ne dépend pas que de la température de surface locale mais qu’elle est aussi sous l’influence d’autres facteurs (dynamique atmosphérique, sources et transport de l’humidité, phénomènes post-déposition). Dans ce rapport, deux sites de forages de carottes courtes du programme ASUMA ont été étudiés dans l’objectif de faire un transect le long de la pente menant au haut plateau antarctique, entre les points D47 à 1550 m d’altitude et STOP_0 à 2460m. Les mesures isotopiques effectuées ont permis de reconstruire la variabilité climatique sur les 50 dernières années grâce à une méthode analytique continue, l’analyse en flux continu ou CFA (« Continuous Flow Analysis »). Bien que cette méthode soit utilisée en laboratoire depuis quelques années, elle a été récemment développée au LSCE sur les carottes de névé. |
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1205 |
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8493 |
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Elisa Floch |
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Catalogage de métadonnées polaires |
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Master 1 |
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2022 |
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Rapport de stage de master 1, université de rennes 1 (encadrement : d. renault, r. georges) |
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136 |
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8496 |
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Elisa Floch |
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Catalogage de métadonnées polaires |
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Master 1 |
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2022 |
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Rapport de stage de master 1, université de rennes 1 (encadrement : d. renault, r. georges) |
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136 |
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8497 |
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Meeta Cesler-Maloney, William R. Simpson, Tate Miles, Jingqiu Mao, Kathy S. Law, Tjarda J. Roberts |
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Title |
Differences in Ozone and Particulate Matter Between Ground Level and 20 m Aloft are Frequent During Wintertime Surface-Based Temperature Inversions in Fairbanks, Alaska |
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Year |
2022 |
Publication |
Journal of Geophysical Research: Atmospheres |
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127 |
Issue |
10 |
Pages |
e2021JD036215 |
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Alaska inversion ozone PM2.5 pollution vertical |
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During winter in Fairbanks, Alaska, fine particulate matter (PM2.5) accumulates to large concentrations at breathing level; yet little is known about atmospheric composition aloft. To investigate vertical differences of pollutants, we measured PM2.5 and ozone (O3) at 3 and 20 m above ground level (AGL) in Fairbanks during winter (November 2019–March 2020). We measured temperature and PM2.5 at 3, 6, 9, and 11 m AGL on a tower to quantify surface-based temperature inversions (SBIs) and near-surface PM2.5 gradients. We defined SBIs as data with an 11 m minus 3 m temperature difference greater than 0.5°C. We observed the largest differences in PM2.5 and O3 when SBIs were present. During SBIs, PM2.5 accumulated to large concentrations at 3 m but to a lesser extent at 20 m, demonstrating reduced vertical mixing. During SBIs, the median PM2.5 concentration was 4.8 μg m−3 lower at 20 m than at 3 m. When PM2.5 concentrations were large at 3 m, O3 was often completely chemically removed (titrated) but was still present at 20 m. During SBIs, the O3 mixing ratio was more than 2 nmol mol−1 larger at 20 m than at 3 m in 48% of the data. Results show that during SBIs, pollution in Fairbanks is mixed to altitudes below 20 m AGL and that the oxidation regime of the atmosphere changes from 3 to 20 m AGL as large differences in O3 mixing ratios were measured during SBIs. |
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2169-8996 |
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8503 |
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Knut von Salzen, Cynthia H. Whaley, Susan C. Anenberg, Rita Van Dingenen, Zbigniew Klimont, Mark G. Flanner, Rashed Mahmood, Stephen R. Arnold, Stephen Beagley, Rong-You Chien, Jesper H. Christensen, Sabine Eckhardt, Annica M. L. Ekman, Nikolaos Evangeliou, Greg Faluvegi, Joshua S. Fu, Michael Gauss, Wanmin Gong, Jens L. Hjorth, Ulas Im, Srinath Krishnan, Kaarle Kupiainen, Thomas Kühn, Joakim Langner, Kathy S. Law, Louis Marelle, Dirk Olivié, Tatsuo Onishi, Naga Oshima, Ville-Veikko Paunu, Yiran Peng, David Plummer, Luca Pozzoli, Shilpa Rao, Jean-Christophe Raut, Maria Sand, Julia Schmale, Michael Sigmond, Manu A. Thomas, Kostas Tsigaridis, Svetlana Tsyro, Steven T. Turnock, Minqi Wang, Barbara Winter |
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Title |
Clean air policies are key for successfully mitigating Arctic warming |
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2022 |
Publication |
Communications Earth & Environment |
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3 |
Issue |
1 |
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1-11 |
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Atmospheric chemistry Climate-change mitigation |
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A tighter integration of modeling frameworks for climate and air quality is urgently needed to assess the impacts of clean air policies on future Arctic and global climate. We combined a new model emulator and comprehensive emissions scenarios for air pollutants and greenhouse gases to assess climate and human health co-benefits of emissions reductions. Fossil fuel use is projected to rapidly decline in an increasingly sustainable world, resulting in far-reaching air quality benefits. Despite human health benefits, reductions in sulfur emissions in a more sustainable world could enhance Arctic warming by 0.8 °C in 2050 relative to the 1995–2014, thereby offsetting climate benefits of greenhouse gas reductions. Targeted and technically feasible emissions reduction opportunities exist for achieving simultaneous climate and human health co-benefits. It would be particularly beneficial to unlock a newly identified mitigation potential for carbon particulate matter, yielding Arctic climate benefits equivalent to those from carbon dioxide reductions by 2050. |
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1255 |
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2662-4435 |
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8505 |
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Cynthia H. Whaley, Rashed Mahmood, Knut von Salzen, Barbara Winter, Sabine Eckhardt, Stephen Arnold, Stephen Beagley, Silvia Becagli, Rong-You Chien, Jesper Christensen, Sujay Manish Damani, Xinyi Dong, Konstantinos Eleftheriadis, Nikolaos Evangeliou, Gregory Faluvegi, Mark Flanner, Joshua S. Fu, Michael Gauss, Fabio Giardi, Wanmin Gong, Jens Liengaard Hjorth, Lin Huang, Ulas Im, Yugo Kanaya, Srinath Krishnan, Zbigniew Klimont, Thomas Kühn, Joakim Langner, Kathy S. Law, Louis Marelle, Andreas Massling, Dirk Olivié, Tatsuo Onishi, Naga Oshima, Yiran Peng, David A. Plummer, Olga Popovicheva, Luca Pozzoli, Jean-Christophe Raut, Maria Sand, Laura N. Saunders, Julia Schmale, Sangeeta Sharma, Ragnhild Bieltvedt Skeie, Henrik Skov, Fumikazu Taketani, Manu A. Thomas, Rita Traversi, Kostas Tsigaridis, Svetlana Tsyro, Steven Turnock, Vito Vitale, Kaley A. Walker, Minqi Wang, Duncan Watson-Parris, Tahya Weiss-Gibbons |
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Model evaluation of short-lived climate forcers for the Arctic Monitoring and Assessment Programme: a multi-species, multi-model study |
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2022 |
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Atmospheric Chemistry and Physics |
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22 |
Issue |
9 |
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5775-5828 |
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While carbon dioxide is the main cause for global warming, modeling short-lived climate forcers (SLCFs) such as methane, ozone, and particles in the Arctic allows us to simulate near-term climate and health impacts for a sensitive, pristine region that is warming at 3 times the global rate. Atmospheric modeling is critical for understanding the long-range transport of pollutants to the Arctic, as well as the abundance and distribution of SLCFs throughout the Arctic atmosphere. Modeling is also used as a tool to determine SLCF impacts on climate and health in the present and in future emissions scenarios. In this study, we evaluate 18 state-of-the-art atmospheric and Earth system models by assessing their representation of Arctic and Northern Hemisphere atmospheric SLCF distributions, considering a wide range of different chemical species (methane, tropospheric ozone and its precursors, black carbon, sulfate, organic aerosol, and particulate matter) and multiple observational datasets. Model simulations over 4 years (2008–2009 and 2014–2015) conducted for the 2022 Arctic Monitoring and Assessment Programme (AMAP) SLCF assessment report are thoroughly evaluated against satellite, ground, ship, and aircraft-based observations. The annual means, seasonal cycles, and 3-D distributions of SLCFs were evaluated using several metrics, such as absolute and percent model biases and correlation coefficients. The results show a large range in model performance, with no one particular model or model type performing well for all regions and all SLCF species. The multi-model mean (mmm) was able to represent the general features of SLCFs in the Arctic and had the best overall performance. For the SLCFs with the greatest radiative impact (CH4, O3, BC, and SO42-), the mmm was within ±25 % of the measurements across the Northern Hemisphere. Therefore, we recommend a multi-model ensemble be used for simulating climate and health impacts of SLCFs. Of the SLCFs in our study, model biases were smallest for CH4 and greatest for OA. For most SLCFs, model biases skewed from positive to negative with increasing latitude. Our analysis suggests that vertical mixing, long-range transport, deposition, and wildfires remain highly uncertain processes. These processes need better representation within atmospheric models to improve their simulation of SLCFs in the Arctic environment. As model development proceeds in these areas, we highly recommend that the vertical and 3-D distribution of SLCFs be evaluated, as that information is critical to improving the uncertain processes in models. |
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1680-7316 |
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8506 |
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Julia Maillard |
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Title |
Boundary layer processes impacting the surface energy balance in the Arctic // Processus de la couche limite Arctique et impact sur le bilan d'énergie en surface |
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Thesis |
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2022 |
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Thèse de doctorat en Physique de l'atmosphère, Sorbonne Université, Juillet 2022 |
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551.51 Arctic Arctique Arctique -- Climat Boundary-layer Clouds Couche limite Couche limite (météorologie) Inversions de température Modélisation Nuages Nuages -- Arctique Observations Physique de l'atmosphère Température atmosphérique -- Arctique -- Modèles mathématiques |
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L'Arctique se réchauffe deux à trois fois plus vite que le reste de la Terre, et c'est donc une zone d'étude cruciale des sciences de l'atmosphère. Cette thèse a pour but d'étudier deux caractéristiques de la couche limite de l'Arctique (les nuages et les inversions de température en surface) et de déterminer leur impact sur le bilan d'énergie de surface en combinant observations et modélisation. Tout d'abord, une nouvelle statistique des caractéristiques nuageuses au-dessus de la banquise a été dérivée d'un ensemble de 1777 profils lidar obtenus au cours de la campagne Ice, Atmosphere, Ocean Observation Systems (IAOOS). Lors de cette campagne, les nuages étaient présents plus de 85% du temps de mai à octobre et l'épaisseur (optique et géométrique) des couches de nuages individuelles était maximale en octobre. Le forçage radiatif total des nuages en été a été était négatif pour les nuages optiquement minces, mais positif pour les nuages optiquement épais. Deuxièmement, l'impact des vitesses de vent sur le développement des inversions de température en surface en Arctique continental a été étudié. L'analyse des mesures de la campagne pré-ALPACA, qui a eu lieu à Fairbanks, Alaska, en hiver 2019, a montré qu'une circulation locale se renforce en conditions anticycloniques. Cet écoulement inhibe le développement de fortes inversions de température en alimentant la turbulence, même lorsque le refroidissement radiatif est très fort. La modélisation des inversions de température en conditions de ciel clair en lien avec la vitesse du vent a ensuite été étudiée, plus particulièrement en zones de couvert forestier. Un modèle analytique à deux couches de la couche de surface végétalisée a été développé. Ce modèle prévoit une diminution plus lente du gradient de température en fonction de la vitesse du vent par rapport à un modèle à une seul couche, et il est cohérent avec les observations menées à un site du réseau Ameriflux près de Fairbanks. En revanche, deux schémas de couche de surface de WRF se sont avérés imposer des limites excessives à la turbulence. |
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8508 |
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Eleftherios Ioannidis |
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Title |
Local and remote sources of Arctic air pollution // Sources locales et éloignées de pollution atmosphérique dans l'Arctique |
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Thesis |
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2022 |
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Thèse de doctorat en Physico-chimie de l'atmosphère, Sorbonne Université, Sept. 2022. |
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551.5113 577.278 Aérosols marins Arctic air pollution Arctique Chimie de l'atmosphère -- Modèles mathématiques Effets du réchauffement de la Terre Local sources Pollution atmosphérique Pollution atmosphérique -- Arctique Sources locales WRF-Chem |
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La région arctique se réchauffe plus rapidement que toute autre région de la planète en raison de l’effet des gaz à effet de serre, notamment le CO2, et des forçeurs climatiques à courte durée de vie d’origine anthropique, comme le carbone suie (BC). Au cours des 20 à 30 dernières années, les émissions anthropiques lointain au-dessus des régions de latitude moyenne ont diminué. Les émissions anthropiques dans l’Arctique y contribuent également et pourraient augmenter à l’avenir et influencer davantage la pollution atmosphérique et le climat de l’Arctique. Les émissions naturelles, telles que les aérosols d’origine marine, pourraient également augmenter en raison du changement climatique en cours. Cependant, les processus et les sources qui influencent les aérosols et les gaz traces dans l’Arctique sont mal quantifiés, surtout en hiver. Dans cette thèse, des simulations quasi-hémisphériques et régionales sont réalisées à l’aide du modèle Weather Research Forecast, couplé à la chimie (WRF-Chem). Le modèle est utilisé pour étudier la composition atmosphérique sur la région Arctique et lors de deux campagnes de terrain, l’une au nord de l’Alaska à Barrow, Utqiagvik en janvier et février 2014 et la seconde à Fairbanks, au centre de l’Alaska en novembre et décembre 2019 lors de la campagne française pré-ALPACA (Alaskan Layered Pollution And Chemical Analysis). Tout d’abord, les aérosols inorganiques et les aérosols de sel marin (SSA) modélisés sont évalués sur des sites arctiques pendant l’hiver. Ensuite, le modèle est amélioré en ce qui concerne les traitements des SSA, après évaluation par rapport aux données de la campagne de Barrow, et leur contribution à la charge totale d’aérosols dans la région arctique est quantifiée. Une série d’analyses de sensibilité est effectuée sur le nord de l’Alaska, révélant des incertitudes du modèle dans les processus influençant les SSA dans l’Arctique, tels que la présence de glace de mer et de chenaux ouverts. Ensuite, une analyse de sensibilité est effectuée pour étudier les processus et les sources qui influencent le BC hivernale dans l’ensemble de l’Arctique et au nord de l’Alaska, en se concentrant sur les traitements de dépôt et les émissions régionales. Des variations de la sensibilité du modèle aux dépôts humides et secs sont constatées dans tout l’Arctique et pourraient expliquer les biais du modèle. Dans le nord de l’Alaska, les émissions régionales provenant de l’extraction pétrolière contribuent de manière importante au BC observée. Les résultats du modèle sont également sensibles aux schémas de paramétrisation de la couche limite. Troisièmement, la version améliorée du modèle est utilisée pour étudier la contribution des sources régionales et locales à la pollution atmosphérique dans la région de Fairbanks pendant l’hiver 2019. En utilisant des émissions actualisées, le modèle donne de meilleurs résultats pour l’hiver 2019 que pour l’hiver 2014, lorsqu’on le compare aux observations effectuées sur des sites de fond en Alaska. Les sous-estimations des aérosols modélisés de BC et de sulfate s’expliquent en partie par le manque d’émissions anthropiques locales et régionales. Dans le cas du sulfate , des mécanismes supplémentaires de formation d’aérosols secondaires dans des conditions sombres/froides doivent également être pris en compte. |
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8509 |
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Brice Temime Roussel, Meeta Cesler-Maloney, Benjamin Chazeau, Amna Ijaz, Natalie Brett, Katharine Law, Slimane Bekki, Jingqiu Mao, Damien Ketcherside, Vanessa Selimovic, Lu Hu, William R. Simpson, Barbara D'Anna |
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Concentrations and Sources of VOCs during wintertime urban pollution at Fairbanks, Alaska |
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2022 |
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AGU Fall Meeting 2022, 11-15 December 2023, San Francisco, USA |
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2022 |
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A51J-04 |
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Fairbanks, Alaska is an urban area that has multiple local emission sources including power plants, domestic heating, and mobile sources, leading to severe wintertime pollution events during cold stable episodes where strong temperature inversions limit pollutant dispersion. In order to evaluate the individual contribution of these sources on Volatile Organic Compounds (VOCs) concentrations, ground-based measurements were carried out at high temporal resolution (2 minutes) using on-line instrumentation (Proton Transfer Reaction Time of Flight Mass Spectrometer: PTR-ToF-MS) during the winter 2022 in downtown Fairbanks as part of the Alaskan Layered Pollution and Chemical Analysis (ALPACA) 2022 field experiment. These measurements are recorded in the urban business district, which probably enhances the traffic component compared to domestic heating. From the detailed analysis of the mass spectra acquired in the 0-500 amu range, more than 330 ions were found of interest for further investigation. Source apportionment analysis was performed using Positive Matrix Factorization (PMF) resolved with the multilinear engine (ME-2) approach. Based on their mass spectral profiles, diurnal cycles and correlation with external collocated measurements (gaseous pollutants: CO, CO2, NOx, SO2, ozone, and specific particulate matter markers), the factors identified could be related to mobile sources (gasoline-like and diesel-like traffic), to heating (residential, diesel-like heating in addition to a couple of specific biomass burning, and to non-combustion sources attributed to secondary processes. This study contributes to the Air Pollution in the Arctic: Climate, Environment and Societies – Alaskan Layered Pollution And Chemical Analysis (PACES-ALPACA) initiative. The French contribution is part of the CASPA (Climate-relevant Aerosol Sources and Processes in the Arctic)/IPEV project. |
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