Performance evaluation of normalized difference chlorophyll index in northern Gulf of Mexico estuaries using the Hyperspectral Imager for the Coastal Ocean |
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| Authors: | Deepak R. Mishra Blake A. Schaeffer Darryl Keith |
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| Affiliation: | 1. Department of Geography, University of Georgia, Athens, GA 30602, USAdmishra@uga.edu;3. National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Durham, NC 27711, USA;4. National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Narragansett, RI 02882, USA |
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| Abstract: | The Hyperspectral Imager for the Coastal Ocean (HICO) was used to derive chlorophyll-a (chl-a) based on the normalized difference chlorophyll index (NDCI) in two Gulf of Mexico coastal estuaries. Chl-a data were acquired from discrete in situ water sample analysis and above-water hyperspectral surface acquisition system (HyperSAS) remote sensing reflectance in Pensacola Bay (PB) and Choctawhatchee Bay (CB). NDCI algorithm calibrations and validations were completed on HICO data. Linear and best-fit (polynomial) calibrations performed strongly with R2 of 0.90 and 0.96, respectively. The best validation of NDCI resulted with an R2 of 0.74 and root-mean-square error (RMSE) of 1.64 µg/L. A strong spatial correspondence was observed between NDCI and chl-a, with higher NDCI associated with higher chl-a and these areas were primarily located in the northern PB and eastern CB at the river mouths. NDCI could be effectively used as a qualitative chl-a monitoring tool with a reduced need for site-specific calibration. |
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| Keywords: | HICO NDCI HyperSAS chlorophyll-a remote sensing reflectance |
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