Aircraft and in Situ Salinity and Ocean Color Measurements: Bridging the Satellite Salinity Coastal Gap

New microwave salinity measuring satellites (SMOS, launched Nov, 2009 and AQUARIUS, to be launched spring 2010) have relatively large pixel size (35-80 km). This does affect their primary ocean missionglobal open ocean salinity measurements on a monthly time scale, to a limited extent. However, the large pixel size has a dramatic effect on measurements near the coast. It requires a large coastal gap in the observed salinity eld, since land brightness temperatures bias the salinity (derived from brightness temperature) for nearshore pixels. One approach to reducing the coastal gap is using optical ocean color as a proxy for salinity. Rivers owing into the coastal ocean carry freshwater as well as CDOM (Colored Dissolved Organic Matter). To the extent that CDOM, like freshwater, is conserved, CDOM concentration changes can serve as a proxy for freshwater dilution by mixing, and hence determine near-surface salinity in coastal waters. However, because CDOM characteristics are determined by unique conditions in each watershed, the relationship of CDOM to salinity can vary for different rivers. We have reported earlier [1] results using STARRS (Salinity, Temperature, and Roughness Remote Scanner airborne instrument) and ocean color from SeaWiFS simulator optical instruments, to estimate salinity in the nearshore region. In this study we will show an aerially derived Ocean Color Salinity algorithm as applied using the SeaWiFS level 1 & 2 normalized water leaving radiance (nwr) data products. In order to retrieve the remote sensing re ectance (Rrs), normalized water leaving radiances are divided by the mean incoming irradiances. To the extent this is successful, it may provide the means to produce a coastal image of SSS with a 4 km resolution. This will show the capability of using ocean color to estimate salinity via optical satellite to a broader coastal zone of the Louisiana Shelf. We address the confounding factors of seasonal and river speci c variation of fresh water sources by applying these results to observations at multiple seasons and locations. We have made multiple STARRS ights, primarily over the northern Gulf of Mexico, and also over the Atlantic Ocean ( ying southeast from Newport News, VA). We apply the methods in [1] to multiple ights and survey regions.