Observations of a Hurricane Katrina‐induced phytoplankton bloom in the Gulf of Mexico

Abstract

A combined dataset of ocean surface winds from the National Center for Environmental Prediction (NCEP), the sea surface temperature (SST) from the Advanced Microwave Scanning Radiometer EOS (AMSR‐E) on Aqua, and ocean color products from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua are used to analyze physical, optical, and biological processes after Hurricane Katrina in the August of 2005. The atmospheric correction algorithm using shortwave infrared (SWIR) bands is employed for the MODIS ocean color data processing. A notable phytoplankton bloom centered at (24.4°N, 84°W) in the Gulf of Mexico is observed four days after Katrina's passing. There was no evidence of sediment re‐suspension and transport from nearby locations into the bloom region. The phytoplankton bloom is attributed to the enhanced nutrient supply brought up by the wind‐driven upwelling and vertical mixing, and is identified as the only source of observed changes in ocean optical and bio‐optical properties.