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Assessment of satellite-derived diffuse attenuation coefficients and euphotic depth in south Florida coastal waters
Jun
Zhao, University of South Florida, junzhao@marine.usf.edu
Using optical data collected from opportunistic cruises in coastal waters off South Florida and in the Caribbean Sea between January 2009 and December 2010, we evaluated several data products derived from MOIDS/Aqua, MODIS/Terra, and SeaWiFS satellite measurements with three bio-optical inversion algorithms. These products included the diffuse attenuation coefficient at 490 nm (Kd_490) and for the visible range (Kd_PAR), and euphotic depth (Zeu, corresponding to 1% of the surface PAR). The large-dynamic range of in situ data (Kd_490) ~ 0.03 – 0.65 m-1) covered a variety of water types in South Florida and the Caribbean Sea, ranging from deep clear waters, turbid coastal waters, and optically shallow waters. Of the three algorithms evaluated, the algorithm based on water’s Inherent Optical Properties (IOPs) yielded the least errors (RMS < 13% for MODIS/Aqua and SeaWiFS) and highest R2 values (often approaching 1.0). The other two algorithms, based on empirical regressions, performed well for offshore clear waters but underestimated Kd_490 and Kd_PAR for nearshore waters due to either high water turbidity or shallow bottom. Similar results were obtained for the Zeu product. A simple empirical model was developed to derive Zeu from Kd_490, which showed the best performance for satellite measurements over nearshore waters. Of the three satellite instruments evaluated, MODIS/Aqua appeared to yield the best results in general. The findings here support future time-series studies of these delicate coastal ecosystems using satellite-based Kd and Zeu with appropriate algorithms and data range. Presentation Type: Poster Session: Science in Support of Decision Making (Wed 10:00 AM) Associated Project(s):
Poster Location ID: 169
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