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González-Toril E, Amils R, Delmas R J, Petit J-R, Komárek J, Elster J, . (2008). Diversity of bacteria producing pigmented colonies in aerosol, snow and soil samples from remote glacial areas (Antarctica, Alps and Andes)
. Biogeosciences Discuss., 5(2), 1607–1630.
Abstract: Four different communities and one culture of pigmented microbial assemblages were obtained by incubation in mineral medium of samples collected from high elevation snow in the Alps (Mt. Blanc area) and the Andes (Nevado Illimani summit, Bolivia), from Antarctic aerosol (French station Dumont d'Urville) and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas). Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. The phylogenetic comparison with the currently available rDNA database allowed the identification of sequences belonging to Proteobacteria (Alpha-, Beta- and Gamma-proteobacteria), Actinobacteria and Bacteroidetes phyla. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified) and the maritime Antarctic soil the poorest (only one). Snow samples from Col du midi (Alps) and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones). These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteria clone). The only microorganism identified in the maritime Antarctica soil (Brevundimonas sp.) was also detected in the Antarctic aerosol. The two snow samples from the Alps only shared one common microorganism. Most of the identified microorganisms have been detected previously in cold environments (Dietzia kujamenisi, Pseudonocardia Antarctica, Hydrogenophaga palleronii and Brebundimonas sp.), marine sediments (Aquiflexus balticus, Pseudomonas pseudoalkaligenes, Pseudomonas sp. and one uncultured Alphaproteobacteria), and soils and rocks (Pseudonocardia sp., Agrobactrium sp., Limnobacter sp. and two uncultured Alphaproteobacetria clones). Air current dispersal is the best model to explain the presence of very specific microorganisms, like those used in this work, in very distant environments. In addition these microorganisms have to be resistant to extreme conditions and able to grow in oligotrophic environments. Considering the habitats in which they have been identified, the presence of pigments must be related with their ability to resist high doses of radiation.
Programme: 355
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Coco I, Amata E, Marcucci M F, Ambrosino D, Villain J-P, Hanuise C, . (2008). The effects of an interplanetary shock on the high-latitude ionospheric convection during an IMF By-dominated period
. Ann. Geophys., 26(9), 2937–2951.
Abstract: On 6 January 1998 an interplanetary shock hit the magnetosphere around 14:15 UT and caused a reconfiguration of the northern high-latitude ionospheric convection. We use SuperDARN, spacecraft and ground magnetometer data to study such reconfiguration. We find that the shock front was tilted towards the morning flank of the magnetosphere, while the Interplanetary Magnetic Field (IMF) was By-dominated, with By<0, IMF Bz>0 and |By|>>Bz. As expected, the magnetospheric compression started at the first impact point of the shock on the magnetopause causing an increase of the Chapman-Ferraro current from dawn to dusk and yielding an increase of the geomagnetic field at the geostationary orbit and on the ground. Moreover, the high-latitude magnetometer data show vortical structures clearly related to the interaction of the shock with the magnetosphere-ionosphere system. In this context, the SuperDARN convection maps show that at very high latitudes above the northern Cusp and in the morning sector, intense sunward convection fluxes appear, well correlated in time with the SI arrival, having a signature typical for Bz>0 dominated lobe reconnection. We suggest that in this case the dynamic pressure increase associated to the shock plays a role in favouring the setting up of a new lobe merging line albeit |By|>>Bz≥0.
Programme: 312;911
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Marchaudon A, Cerisier J-C, Dunlop M W, Pitout F, Bosqued J-M, Fazakerley A N, . (2009). Shape, size, velocity and field-aligned currents of dayside plasma injections: a multi-altitude study
. Ann. Geophys., 27(3), 1251–1266.
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Kuttippurath J, Godin-Beekmann S, Lefèvre F, Goutail F, . (2010). Spatial, temporal, and vertical variability of polar stratospheric ozone loss in the Arctic winters 2004/052009/10
. Atmos. Chem. Phys. Discuss., 10(6), 14675–14711.
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van der Laan-Luijkx I T, Neubert R E M, van der Laan S, Meijer H A J, . (2010). Continuous measurements of atmospheric oxygen and carbon dioxide on a North Sea gas platform
. Atmos. Meas. Tech., 3(1), 113–125.
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Sirignano C, Neubert R E M, Rödenbeck C, Meijer H A J, . (2010). Atmospheric oxygen and carbon dioxide observations from two European coastal stations 20002005: continental influence, trend changes and APO climatology
. Atmos. Chem. Phys., 10(4), 1599–1615.
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Myriokefalitakis S, Tsigaridis K, Mihalopoulos N, Sciare J, Nenes A, Kawamura K, Segers A, Kanakidou M, . (2011). In-cloud oxalate formation in the global troposphere: a 3-D modeling study
. 1680-7316, 11(12), 5761–5782.
Abstract: Organic acids attract increasing attention as contributors to atmospheric acidity, secondary organic aerosol mass and aerosol hygroscopicity. Oxalic acid is globally the most abundant dicarboxylic acid, formed via chemical oxidation of gas-phase precursors in the aqueous phase of aerosols and droplets. Its lifecycle and atmospheric global distribution remain highly uncertain and are the focus of this study. The first global spatial and temporal distribution of oxalate,
simulated using a state-of-the-art aqueous-phase chemical scheme embedded within the global 3-dimensional chemistry/transport model TM4-ECPL, is here presented. The model accounts for comprehensive gas-phase chemistry and its coupling with major aerosol constituents (including secondary organic aerosol). Model results are consistent with ambient observations of oxalate at rural and remote locations (slope = 1.16±0.14, r2 = 0.36, N =114) and suggest that aqueous-phase chemistry contributes significantly to the global atmospheric burden of secondary organic aerosol. In TM4-ECPL most oxalate is formed in-cloud and less than 5% is produced in aerosol water. About 62% of the oxalate is removed via wet deposition, 30% by in-cloud reaction with hydroxyl radical, 4% by in-cloud reaction with nitrate radical and 4% by dry deposition. The in-cloud global oxalate net chemical production is calculated to be about 21–37 Tg yr-1 with almost 79% originating from biogenic hydrocarbons, mainly isoprene. This condensed phase net source of oxalate in conjunction with a global mean turnover time against deposition of about 5 days, maintain oxalate’s global tropospheric burden of 0.2–0.3 Tg, i.e. 0.05–0.1 Tg-C that is about 5–9% of model-calculated water soluble organic carbon burden.
Programme: 415
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Smirnov A, Holben B N, Giles D M, Slutsker I, O'Neill N T, Eck T F, Macke A, Croot P, Courcoux Y, Sakerin S M, Smyth T J, Zielinski T, Zibordi G, Goes J I, Harvey M J, Quinn P K, Nelson N B, Radionov V F, Duarte C M, Losno R, Sciare J, Voss K J, Kinne S, Nalli N R, Joseph E, Krishna Moorthy K, Covert D S, Gulev S K, Milinevsky G, Larouche P, Belanger S, Horne E, Chin M, Remer L A, Kahn R A, Reid J S, Schulz M, Heald C L, Zhang J, Lapina K, Kleidman R G, Griesfeller J, Gaitley B J, Tan Q, Diehl T L, . (2011). Maritime aerosol network as a component of AERONET first results and comparison with global aerosol models and satellite retrievals
. 1867-1381, 4(3), 583–597.
Abstract: The Maritime Aerosol Network (MAN) has been collecting data over the oceans since November 2006. Over 80 cruises were completed through early 2010 with deployments continuing. Measurement areas included various parts of the Atlantic Ocean, the Northern and Southern Pacific Ocean, the South Indian Ocean, the Southern Ocean, the Arctic Ocean and inland seas. MAN deploys Microtops handheld sunphotometers and utilizes a calibration procedure and data processing traceable to AERONET. Data collection included areas that previously had no aerosol optical depth (AOD) coverage at all, particularly vast areas of the Southern Ocean. The MAN data archive provides a valuable resource for aerosol studies in maritime environments. In the current paper we present results of AOD measurements over the oceans, and make a comparison with satellite AOD retrievals and model simulations.
Programme: 415
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Hendrick F, Pommereau J-P, Goutail F, Evans R D, Ionov D, Pazmino A, Kyrö E, Held G, Eriksen P, Dorokhov V, Gil M, Van Roozendael M, . (2011). NDACC/SAOZ UV-visible total ozone measurements: improved retrieval and comparison with correlative ground-based and satellite observations
. Atmos. Chem. Phys., 11(12), 5975–5995.
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Bencherif H, El Amraoui L, Kirgis G, Leclair De Bellevue J, Hauchecorne A, Mzé N, Portafaix T, Pazmino A, Goutail F, . (2011). Analysis of a rapid increase of stratospheric ozone during late austral summer 2008 over Kerguelen (49.4° S, 70.3° E)
. Atmos. Chem. Phys., 11(1), 363–373.
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