Satellite Optical Water Mass Classification to Map Coastal Hypoxia

摘要

We applied an optical water mass classification technique to estimate the areal extent of coastal hypoxia in the northern Gulf of Mexico. Partitioned absorption coefficients (phytoplankton, sediment/detrital, and CDOM) derived from satellite ocean color imagery are coupled with a stratification index (surface-to-bottom temperature difference) derived from a circulation model. Optical properties (relative and absolute absorption coefficients) were extracted from a 10-year climatology of monthly satellite composites to define expected optical conditions of hypoxic waters, which were delineated by mid-summer ship surveys (LUMCON, 2009). Then, for a given year, the satellite-derived optical properties are compared to the expected conditions and coupled with the model-derived water column stratification index, to provide a real-time spatial estimate of hypoxia.