Veronique Garcon, Vers SOLAS 2025 ( PDF).
Le projet SOLAS (IGBP, SCOR, WCRP, ICACGP) a demarré en 2000 avec la Open Science Conference à Damp en Allemagne et le premier Science and Implementation Strategy Plan fut publié en 2004. En 2008, le comité Scientifique a revisité certains des thèmes, les Mid-Term Strategy initiatives, qui nécessitaient une collaboration internationale renforcée (Law et al., 2013). En 2015, le paysage institutionnel et programmatique en sciences du changement global a profondément évolué au niveau international par la disparition de IGBP fin 2015 et l'émergence de Future Earth.Le nouveau SOLAS Science Plan 2015-2025 sera présenté ainsi que la transition vers Future Earth et les enjeux qui y sont associés.
Sandrine Paillard, Future Earth ( PDF).
Séverine Alvain, Polar Pod ( PDF).
Marion Benetti, What have we learned on air-sea vapor exchange from water isotopologue measurements during cruises in the tropical and subtropical Atlantic (SPURS, PIRATA, Rara Avis) ( PDF).
Rachel Shelley, Geraldine Sarthou, Eric Machu, Habib Senghor, Muntsa Roca Marti, Pere Masque, Georges Tymen, Christophe Messager, Thomas Gorgues, Hamet Diadhiou, Patrice Brehmer, Trace element composition, solubility and flux estimates of aerosols from contrasting regions of the North Atlantic Ocean (GEOTRACES GA01 and offshore Senegal) ( PDF).
Atmospheric deposition of aerosols is an important source of trace elements (TE) to the surface ocean. Aerosols contain both essential bioactive elements, e.g. Fe, Cu, Co, Zn, and pollution-derived elements which have no known biological role, e.g. Pb. In particular, the aerosol Fe flux is a key component of biogeochemical and ecosystem models. At present, TE flux estimates are poorly constrained. The largest contribution to this uncertainty results from the use of a fixed deposition velocity. In this study, we take a novel approach to estimate TE fluxes. Beryllium-7 (7Be) is a cosmogenically-formed radioisotope (T1/2=53 days). By multiplying the water column inventory of 7Be activity with the TE/7Be ratio in the bulk aerosol we are able to significantly reduce the uncertainty of the flux estimates. As only a certain fraction of the aerosol TE are soluble (the most readily bioavailable fraction), it is of paramount importance to determine this fraction. To this end, samples were collected from two contrasting regions of the North Atlantic Ocean. Data is presented from the French-GEOTRACES cruise (GA01) which sampled a low aerosol regime (e.g. total aerosol Fe = 0.19-18.7 ng Fe m-3 air filtered), and from the AWA series of cruises (ECOAO, Upsen-2, AWA) off the coast of Senegal, under the Saharan plume with tropical influence (Fe = 52.4-3471ng Fe m-3 air filtered). Aerosol-Fe solubility was lowest for the AWA samples (<0.5% soluble in DI water). However, what the combined effects of changing meteorological conditions, increasing industrialisation and land-use changes will have on aerosol solubility is largely unknown.
Guieu et al., Atmospheric impact on ocean biogeochemistry: from experiments to modelling ( PDF).
E. Journet, S. Lafon, M. Bandak, S. Nowak, S. Chevaillier, P. Ausset, B. Laurent, Dust mineralogical composition to study Iron nutrient solubility (FERATMO+ project) ( PDF).
Violaine Gérard (CNRS/Ircelyon), Barbara Nozière (CNRS/Ircelyon), Christine Baduel (The University of Queensland, Australia), Amanda Frossard (UC Berkeley, USA) et Ron. C. Cohen (UC Berkeley, USA), Surface tension and anionic, cationic, and non-ionic surfactant concentration in aerosols from contrasting regions: filling the gaps in the ecosystems-aerosol-cloud relationship ( PDF).
K. Sellegri, A. Culot, C. Rose, J. pey, S. Mas, B. D’anna, R. Sempere B. Charriere and N. Marchand, Secondary aerosol emissions from open sea waters via halogenated species: evidences from mesocosm experiments
New particle formation through the gas-to-particle conversion is an important and complex process that generate aerosols which can, in turn, affect the climate on a global scale by influencing cloud radiative processes (Slingo, 1990). This phenomenon has been widely studied in many environments, including marine coastal areas where the largest nucleation rates have been reported so far in the literature, when macro-algae are exposed to ambient air at low tide during daytime. However, extremely scarce information is available for open-ocean conditions which represent 71 % of the earth surface. Nucleation is suspected to occur over open ocean areas (O’Dowd (2010)), but there were, to our knowledge, no direct measurement of new cluster particle significant formation. Iodine has been identified as a precursor to formation of new particles in coastal environment (O’Dowd 2002), and is also released by microalgae species (Thorenz et al. 2014), but in-situ measurement failed to identify iodine as a precursor to new particle formation events in the open-ocean atmosphere. Here, we evidence that new cluster particles (1-6 nm of diameter) are abundantly produced from open-sea-representative seawater, free of coastal macro-algae, from mesocosm experiments.
Kahina DJAOUDI, Elvira PULIDO-VILLENA et France VAN WAMBEKE, Rôle de l'apport atmosphérique sur les processus de biodégradation et la stœchiométrie de la matière organique dissoute en mer Méditerranée. ( PDF).
Pulido-Villena, E., Djaoudi, K., Charrière, B., Delmont, A., Helias-Nunige, S., Tedetti, M., Van-Wambeke, F. , Experimental evidence of dust-induced changes in DOM bioavailability in the surface ocean ( PDF).
H. El Masri, N. Visez and D. Petitprez, Lab measurements of oxydation of fatty acid in marine organic aerosol ( PDF).
Marine Claeys, Développements en cours dans le modèle Méso-NH pour la génération des sels marins primaires ( PDF).
Zihan Qu, Aerosol at Rio Gallegos, Patagonia. ( PDF).
Patagonia (South America) is a major atmospheric mineral dust source in the South Hemisphere. The input of Patagonian dust plays a critical role in the biogeochemistry of Southern Ocean. From November 2011 to August 2014, aerosol samples were continuously collected on a weekly basis in Río Gallegos (69.32°W, 51.60°S), by the south Patagonia east coast. This three-year measurement is the first long term time series of mineral dust concentrations obtained in the sub-Antarctic region. Backward trajectories by HYSPLIT model showed that up to 90% of air mass arrived at Río Gallegos originated from the west side (between NNW and SSW) of sampling site. Amounts of Al, Si and Fe were determined by XRF analysis. The compositions of the three elements remained stable during the three years samplings. Weekly dust concentrations measured in South Patagonia varied from 0.07 to 3.68 µg.m-3 and reveals a strong seasonal variation pattern. Average winter dust concentrations could decrease down to five times lower than in other seasons. Higher wind speeds unexpectedly did not result in higher dust concentrations. However, variations of the temperature and the air relative humidity correlated significantly with the dust concentration variation. This suggests that surface soil moisture changes are the primary regulating factor of dust concentration variation in Patagonia. Land frozen effect was potentially another factor resulting low level of dust concentration in winter. The temperature and relative humidity dependence of seasonal dust concentration variation implicate a feedback of dust emission in response to short term climate variations. Our results permit also the improvement of atmospheric dust modelling in the South Hemisphere.
This work is in SOLAS scope, and is supported by French project “Dust From Patagonia” (CNRS-INSU, LEFE/CHAT) and France-Argentina cooperation program “ASAR” (ECOS-Sud).
C. Lo Monaco, N. Metzl, F. d'Ovidio, J. Llort, C. Ridame, R. Gomez, C. Mignon, V. Racapé , S. Blain et B. Quéguiner, Seasonal cycles of air-sea CO2 fluxes in the Southern Ocean: what do we learn from observations around Kerguelen?
Iron, light and silicic acid availability are the main factors limiting the biological CO2 uptake in the Southern Ocean (south of 50°S), leading to a small uptake of atmospheric CO2 in this region (~0.1 PgC/yr). Iron fertilization experiments have demonstrated the potential for increased CO2 uptake for short periods (a few weeks), but little is known about the seasonal evolution of biogeochemical cycles in iron-fertilized ecosystems. In the frame of the KEOPS2 and OISO projects, observations were collected in October-November 2011 over and downstream of the Kerguelen Plateau, allowing to investigate for the first time the mechanisms that control the oceanic CO2 uptake at the onset of the blooming period. As soon as vertical mixing is reduced, we observed the rapid establishment of strong CO2 sinks in waters fertilized with iron (up to -20 mmolC/m²/d). We then used all data available since 1991 to draw the seasonal evolution of air-sea CO2 fluxes in different regions of Kerguelen’s phytoplankton bloom. The impact of iron fertilization on the ocean CO2 uptake is revealed by comparing estimates in the bloom (1-1.5 molC/m²/yr) and in the iron-poor waters (about 0.4 molC/m²/yr). Extrapolating these results to the large High-Nutrient Low-Chlorophyll area in the Southern Ocean (~50°S-60°S) suggests that iron fertilization may increase the uptake of atmospheric CO2 by less than 0.1 PgC/yr, i.e., less than 1% of the current anthropogenic CO2 emissions.
Aurélien PAULMIER, Marine BRETAGNON, Boris DEWITTE, Véronique GARCON, Christophe MAES, Fernando CAMPOS, Augusto FRANCO-GARCIA, Koby MOSQUERA, Oscar VERGARA, Carole BARUS, Laurent COPPOLA, Edgardo CARRASCO, Olivier DEPRETZ-DE-GESINCOURT, Gérard ELDIN, Emilio GARCIA-ROBLEDO, Jacques GRELET, Séréna ILLIG, Ivonne MONTES, Nathalie LEBLOND, Andreas OSCHLIES, Jorge QUISPE, Joël SUDRE, Oxygen Minimum Zone (OMZ) dynamics in the context of the ocean deoxygenation: the case off Peru from the AMOP «Activities of research dedicated to the Minimum of Oxygen in the eastern Pacific» project - Poster
Oxygen Minimum Zones (OMZs), defined as suboxic (O2 <20 µmol/L) subsurface layer and mainly associated with Eastern Boundary Upwelling Systems (EBUS), would contract and expand during cold and warming periods, respectively. In the current context of the ocean deoxygenation, OMZs are known to play a key-role on the evolution of climate (greenhouse gases) and on the ecosystems and fisheries (nitrogen loss, respiratory barrier, sulfidic events) at both local and global scales. The objective of AMOP project (“Activties of research dedicated to the Minimum of Oxygen in the eastern Pacific”)is to carry out a complete O2 budget off Peru considering physical (advection/diffusion) and biological (O2 consumption/production) contributions. The central hypothesis is that the physical and biogeochemical O2 contribution to the OMZ maintaining and variability depends on the different OMZ layers, in particular the oxycline which would be the engine of an intense but intermittent biogeochemical and ecosystem activity. The project is focused in one of the most intense and shallow OMZs associated with the most productive upwelling system (10 % of the world fisheries), the Peruvian OMZ. The trans-disciplinary approach is based on: a cruise (January-February 2014; in the Peruvian OMZ) focused on 8 fixed stations (~54 h) on 3 transects at 7°S, 12°S and 14°S with the RV Atalante associated with an effort of experimental development (instrumentation, sensors: argo-floats experiments; drifting lines; a trimaran dedicated to ocean-atmosphere exchanges; nanomolar O2 measurements); a monitoring (2013-2014) mooring at 12°S at 30 nm from the coast; a complementary high resolution regional coupled modeling platform integrating the different spatio-temporal scales. This French-Peruvian-German project involving 5 other countries (~90 participants) is viewed as one of the main pilot projects of the SOLAS Mid Term Strategy Initiative on OMZ-EBUS. Preliminary results, in particular from recent high frequency (15-30 min) mooring data complemented with models simulations show a intra-annual variability of the OMZ dynamics associated with the productivity and environmental forcing (i.e. tide, wind-forced upwelling, meso-scale activity and equatorial Kelvin wave). For the first time, three main regimes of variability have been reported (sub-daily: < 1 day; sub-monthly: 1-30 days; sub-seasonal: 30-90 days), which should be taken into account for the validation of regional models and the interpretation of the evolution of marine resources along the coast of Peru. Cruise and fixed and drifting sediment traps core parameters (including nanomolar O2 and nutrients, organic matter, and respiratory rates from incubations) will be analyzed in order to estimates the physical and biogeochemical contributions to the OMZ dynamics. In particular, the influence of the phytoplankton on the OMZ and of the OMZ on the organic matter quantity and quality will be explored.
Céline Ridame, Violaine Jacq,Stéphane L’helguen, Desboeufs Karine, Impact of atmospheric iron from Saharan dust on /Crocosphaera watsonii
Laurie Perrot, Diana Ruiz-Pino, Francis Gohin ( PDF).
Calcareous phytoplankton group (coccolithophores) has an ubiquist repartition and is the main calcifying organism in the open ocean. At a global scale coccolithopore blooms are studied in regard of CaCO3 production and three potential feedback on climate change: albedo modification by the way of dimethylsulfide (DMS) production and atmospheric CO2 source by calcification and a CO2 pump by photosynthesis
Contradictory assumptions were pointed out about the evolution of coccolithophore blooms during the anthropogenic era. At one hand, calcification and coccolithophores blooms extension could be decreasing as a consequence of acidification (pH decrease). At the contrary an extension and an increase of blooms and propagation to high latitudes have been pointed out by recently studies. The remote-sensing approach based on Ocean Colour data give us a large temporal and spatial view allowing us to understand the phenology of these calcareous phytoplankton blooms. Determination of the trend of blooms, from satellite data, in a long term view (inter-annual variability), needs the discrimination of the coccolithophore signal from other active materials, such as mineral particles (Suspended Particulate Matter SPM) mainly in coastal waters.
To detect coccolithophores from satellite reflectance and overcome the induced noise in the signal calcareous phytoplankton SPM signal we developed a method based on fuzzy mathematical scheme principles. It uses as input the 6 wave lengths (412, 443, 488, 532, 550, 670) of colour satellite reflectance signal of the SeaWifs and MODIS satellite and extracted from the SPM signal the associated signal of coccolithophores. The calibration of the algorithm is made from Suspended Particulate Matter (SPM) concentration derived from SeaWiFS (1998-2002) and MODIS (2003-2014) reflectance obtained in a region of strong bloom of coccolithophores: North-East Atlantic ocean. The algorithm is calibrated with in-situ taxonomic data obtained during the years 98 and 99.The SPM concentration derived from the semi-analytical algorithm appear to be well correlated to the coccolithophores mass derived from the NASA calcite algorithm. Although a regular pattern in the phenology of the North east Atlantic blooms is observed, starting south in April and moving northwards until July, there is a high temporal (seasonal and inter-annual) variability in the blooms extension.
To be used at global scale and for the long trend studies the method has to be validate in other oceanic region where in-situ observation of coccolithophores has been obtained. This method applied to the reflectance of chlorophyll pixels could provide a daily and quantitative variability of other groups of phytoplankton as a function of their spectral reflectance.
Rémi Losno, Alexie Heimburger, Antoine Cogez, Fabrice Monna and Jérôme Gaillardet, Dust transport from Patagonia to Kerguelen. ( PDF).
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