1. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 Characterization of Global Ocean Turbidity from MODIS Aqua Ocean Color Observations Wei Shi 1 and Menghua Wang 2 (GOVERNMENT PRINCIPAL INVESTIGATOR) 1 CIRA,, 2NOAA/NESDIS/STAR The NIR-SWIR combined atmospheric correction algorithm and a new K d (490) algorithm have been used to derive K d (490) data to study and quantify seasonal global ocean turbidity for both the global open ocean and coastal turbid waters.  Global ocean turbidity shows significantly seasonal K d (490) variations with highs in the boreal (or austral) spring and summer and lows in the winter for the northern (or southern) hemisphere.  Global clear waters with K d (490) >=0.05 m -1 and 0.05 m -1 <K d (490) <=0.1 m -1 account for 83% and 13%of the global ocean coverage.  Turbid waters with K d (490) over 0.3 m -1 are all located along the coastal regions, river estuaries, and inland lakes with a global coverage of ~2–3  10 6 km 2, accounting for ~8–12% of the total global continental shelf area.  Amazon River estuary ranks the world’s most turbid region with the mean K d (490) value ~5 m -1.The highly turbid waters include: (1) China’s east coast region, (2) U.S. east coast region and northern Gulf of Mexico, (3) Amazon River estuary, (4) La Plata River estuary, (5) Ganges River estuary and Gulf of Martaban in the Bay of Bengal, (6) Caspian Sea, (7) North Sea Region and (8) Gulf of Carpentaria between Australia and New Guinea.  In US East Coast, turbid waters are primarily located in the Chesapeake Bay, Delaware Bay, and Pamlico Sound within the Outer Banks. Highly turbid regions with K d (490) > ~2 m -1 are located at the upper Chesapeake Bay and Delaware Bay. MODIS K d (490) CLIMATOLOGY IN US EAST COAST DURING 2002 - 2008 January April July October  Seasonal phytoplankton bloom dominates the global geographic perspective of the modestly turbid waters (for waters with 0.1 m -1 < K d (490) ≤ 0.3 m -1 ).  In the coastal region, high turbidity (K d (490) > 0.3 m -1 ) is attributed to the high loading of sediment concentration due to various physical processes, such as sediment re-suspension, river run off MECHANISMS FOR MODESTLY TURBID AND HIGHLY TURBID WATERS K d (490) in July, 2005 (scale: 0.03-1.0 log) nLw(645) in July 2005‏ (scale: 0-6) Jul. 2005 Oct. 2005 SEASONAL GLOBAL OCEAN K d (490) April. 2005 Jan. 2005 Chlorophyll-a Concentration in July, 2005 (scale: 0.1-32 log) K d (490) in July, 2005 (scale:0-5) 0.031.0 5.0 0.0 log m -1 Requirement: Ecosystems: (1) Advancing understanding of ecosystems to improve resource management, (2) Healthy and productive coastal and marine ecosystems that benefit society. Science: How to characterize and quantify global ocean turbidity for both open ocean and coastal waters, understand different ocean and atmospheric processes that control the variability of ocean turbidity? Benefit: Better understand global ocean ecosystem and water quality, help refining the ocean and atmosphere models and improve the prediction accuracy. Science Challenges: Inter-annual variability of the global ocean turbidity and its relation to the decadal and long term ocean and atmospheric variability. Next Step: Regional studies of the seasonal and inter-annual ocean turbidity. Transition Plan: Transition newly developed K d (490) algorithm for the operational use.