The Northwestern Tropical atlantic is a region of great importance within the salinity mission context due to the large freshwater flux from the discharge of the Amazon and Orinoco rivers, and their interactions with northward propagating eddies from the retroreflection of the North Brazil Current (NBC).

AMSR-E SSS estimates were then validated using a complement of sources. Recent ocean color work (e.g., Hu et al. [2004]) demonstrated the strong negative correlation between satellite-derived colored dissolved organic matter (CDOM) and the surface salinity in the Amazon plume region. To support spatial validation in this study, composite of SeaWiFS and MODIS products are used to produce CDOM maps as a proxy for delineating the spatial extent and patterns of the Amazon and Orinoco freshwater plumes. In addition, both a climatology (Reverdin et al. [2007]) and a match-up data base between in situ upper layer salinity measurements and AMSR-E estimates are used for quantitative evaluation.

The results for each month of the year 2003 are shown below.Each set of figure for each month has 4 subplots (click on images for a bigger size plot ). Subplot (a) is the monthly averaged difference in estimated flat sea surface brightness temperature between 6.9 and 10.7 GHz frequencies in vertical polarization, (b) is the corresponding monthly averaged AVHRR-AMSR OI 0.25° sea surface temperatures, (c) is the monthly composite map of the colored dissolved organic matter (CDOM) absorption coefficient obtained with the GSM model and the SeaWiFS and MODIS sensors and (d) is the monthly averaged sea surface salinity retrieved from AMSR-E. The black contour lines on each figure represent the levels of the CDOM absorption coefficient, used here as an independent proxy for delineating the spatial extent and patterns of the Amazon and Orinoco freshwater plumes.