Mineral dust and carbonaceous aerosols in West Africa : source assessment and characterization

International audienceAs part of the AMMA (African Monsoon Multidisciplinary Analysis) international research project, an intensive field campaign called "Special Observing Period" (SOP 0) was carried out in WestAfrica during the dry season (February 2006), near M'Bour, Senegal. The aim of the ground-based sampling experiment was to determine the chemical composition of dust and carbonaceousaerosols in the surface layer, then to investigate the main source areas influencing the chemical composition of the particles. Major elements (Al, Ca and Fe), total (TC) and black carbon (BC), and water soluble ion (Na+, K+, Mg2+, NH4+, Cl−, NO3−, and ) concentrations were measured. Total mass, number concentration and aethalometer measurements of PM-10 were also obtained. Mineraldust in the surface layer is principally present in the coarse fraction representing 75-90% of the collected mass (wt.%). Dust, suggested by backward trajectories of the air masses and supported by the variations of Ca/Al ratios, originates mainly from Northern Sahara. Particulate organic matter (POM) concentrations are more variable, but POM is mainly present in the fine fraction (up to 77 wt.%). Its presence is due to local sources such as domestic fire emissions rather than to remote sources as open-field vegetation fires in the Sahelian zone. Comparisons of Black Carbon (BC) concentrations measured with an aethalometer in the Ultra-violet and the Near-infrared wavelengths, show that POM originating from the adjacent Western African coast contains less aromatics than POM transported from the main biomass burning areas of the Sahelian zone. Thus, smouldering, the main combustion process for locally emitted carbon aerosols appears to generate less aromatic compounds than burning of vegetation. -------------------------------------------------------------------------------

Hyperspectral versus multispectral remote sensing approach to detect phytoplankton blooms in coastal waters : application to a Phaeocystis bloom.

International audienc

Hyperspectral versus multispectral remote sensing approach to detect phytoplankton blooms in coastal waters : application to a Phaeocystis bloom.

International audienc

Hyperspectral versus multispectral remote sensing approach to detect phytoplankton blooms in coastal waters : application to a Phaeocystis bloom.

International audienc

Hyperspectral versus multispectral remote sensing approach to detect phytoplankton blooms in coastal waters : application to a Phaeocystis bloom.

International audienc

Seasonal and inter-annual (2002-2010) variability of the suspended particulate matter as retrieved from satellite ocean color sensor over the French Guiana coastal waters

International audienceA regional algorithm has been developed for estimating total suspended matter (TSM) concentration over the MODIS time period in the French Guiana coastal waters. The temporal analysis of the 8-year time series (2002-2010) shows very different patterns of temporal variability translating the influence of the various hydrodynamic forcings occurring in this coastal system. Hydrodynamical rings formation associated with the retroflecting North Brazil current system induce strong irregular variations in the TSM loads offshore the Guiana coast. Further, strong significant 8-year interannual changes have been detected along the nearshore waters of French Guiana. The alternance in the distribution of the areas showing increasing and decreasing trends might underline the migration of mud banks particularly dynamic in this coastal regio

Analyze of the inherent optical properties of French Guiana coastal waters for remote sensing applications.

International audienc