Estimating and mapping chlorophyll‐a concentration in Pensacola Bay, Florida using Landsat ETM+ data

Abstract The purpose of this study was to develop algorithms for estimating chlorophyll‐a concentration in Pensacola Bay using Landsat 7 ETM+ data. The techniques used were band ratioing and regression modelling. Pensacola Bay is located on the west end of the Florida panhandle. As one of 39 estuaries located on the Gulf of Mexico, Pensacola Bay is impacted largely by rivers. The Landsat ETM+ data were first geometrically rectified. Then brightness values were converted to reflectance through the radiometric correction process. For the regression models, logarithmically transformed chlorophyll‐a was used as the dependent variable. Single bands, band ratios and logarithmically transformed band ratios were the independent variables. R 2 values were computed and evaluated. Results from the study indicate that the ratio of ETM+1/ETM+3 was the most effective in estimating chlorophyll‐a. Using this model a chlorophyll‐a map was generated for Pensacola Bay. Acknowledgements This research has been supported by a grant from the US Environmental Protection Agency's Science to Achieve Results (STAR) Estuarine and Great Lakes (EaGLe) program through funding to the CEER‐GOM, US EPA Agreement R82945801. Although the research described in this article has been funded wholly or in part by the United States Environmental Protection Agency, it has not been subjected to the Agency's required peer and policy review and therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred. The Gulf Ecology Division of the US EPA provided water quality data and facilitated the spectral data collection. The authors thank Yongtao Luo for providing expertise in image processing and modelling.