Long-Term Trends in Environmental Parameters Along the Louisiana-Mississippi Outer Continental Shelf Using Remote-Sensing Data.

摘要

The Mississippi River is the primary riverine source of freshwater, nutrients, organic/inorganic particulate and dissolved matter to the Louisiana continental shelf and strongly influences biogeochemical processes in the northern Gulf of Mexico (NGOM). The region is also an important center of economic activity associated with a well-developed fisheries and oil and gas industry. Ocean color remote sensing potentially provides the information on regional scales to address the issue of monitoring both short-term and long-term seawater particulate and dissolved matter distributions and an assessment of the effects of both anthropogenic and natural influences on coastal ecosystems. Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite ocean color data together with field observations were used to examine the short-term, seasonal and long-term distribution of colored dissolved organic matter (CDOM) and chlorophyll along the coastal and shelf waters of the Mississippi, Louisiana, and part of Texas coast. A previously derived CDOM empirical algorithm was validated and used to derive estimates of surface CDOM absorption distribution at 412 nm from the SeaWiFS imagery. Spatial and temporal CDOM absorption distributions from satellite for the NGOM indicated strong seasonal influence associated with river discharge and effects of storms. Multiyear time-series satellite derived chlorophyll (Chl) estimates were used to examine the dominant scales of chlorophyll variability in the river-dominated coastal and oceanic waters. Wavelet analysis was applied to almost 10 years (1998-2007) of data and interpreted in conjunction with wind data from QuikSCAT satellite sensor to provide additional insights on the Chl variability in the region.