Spatio-temporal dynamics of inherent optical properties in oligotrophic northern Gulf of Mexico estuaries. (15th August 2018)

• Record Type: Journal Article
• Authors: Astuti, Ike Sari; Mishra, Deepak R.; Mishra, Sachidananda; Schaeffer, Blake
• Is Part Of: Continental shelf research. Volume 166(2018)
• Page Start: 92
• Page End: 107
• Publication Date: 2018-08-15
• Subjects: Hybrid model -- Quasi-analytical algorithm -- Water quality -- Florida estuaries -- MERIS -- Sentinel-3 -- OLCI -- Choctawhatchee Bay -- St. Andrew Bay -- Pensacola Bay -- St. Joseph Bay; Continental shelf -- Periodicals; Submarine geology -- Periodicals; 551.41
• DOI: 10.1016/j.csr.2018.06.016
• Languages: English
• ISSNs: 0278-4343

Abstract

Abstract: Coastal and estuarine ecosystems provide numerous economic and environmental benefits to society. However, increasing anthropogenic activities and developmental pressure may stress these areas and hamper their ecosystem services. Satellite remote sensing could be used as a tool for monitoring water quality parameters, including inherent optical properties (IOP) in coastal regions. Spatio-temporal information on IOP variability will help in understanding the dynamics of the water quality of estuaries. The objective of this research was to develop a novel hybrid model by combining and parameterizing existing quasi analytical and semi-analytical algorithms to estimate IOPs in four oligotrophic northern Gulf of Mexico Florida estuaries. The hybrid model was applied to above surface remote sensing reflectance data representing the Medium Resolution Imaging Spectrometer (MERIS) and Sentinel-3's Ocean and Land Colour Instrument (OCLI) bands. The hybrid model produced a root means squared error (RMSE) of 0.32 m −1 (13.95% NRMSE) for total absorption ( a t ), 0.21 m −1 (7.61% NRMSE) for detritus-gelbstoff absorption ( a dg ), and 0.09 m −1 (22.77% NRMSE) for phytoplankton pigment absorption (a phi ). Results showed that absorption by detritus and gelbstoff (a dg ) dominates the water in these estuaries. Monthly IOP variability in 2010 revealed that compared to other estuaries, magnitudes of IOPs was the highest in Pensacola Bay and therefore the highest attenuation. Findings also indicated that river discharge and precipitation predominantly govern the IOP variations in all four estuaries, showing an increase in IOP values following the high flow period. The hybrid model improved IOP retrieval in these low chlorophyll-a (Chl-a) estuaries where the existing spectral decomposition models did not perform satisfactorily. Highlights: Existing models for inherent optical properties were tested in Florida estuaries. Poor phytoplankton estimates from all modes imply a new estimation approach. A hybrid model combining quasi and semi-analytical models improved the estimation. Spatio-temporal variability of inherent optical properties in FL estuaries is shown. The model has strong potential for water quality using MERIS and Sentinel-3A OLCI.