Term of Award

Fall 2023

Degree Name

Master of Science, Applied Geography

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Geology and Geography

Committee Chair

Christine Hladik

Committee Member 1

John Schalles

Committee Member 2

Munshi Rahman

Committee Member 3

Risa Cohen

Committee Member 3 Email

rcohen@georgiasouthern.edu

Abstract

Water quality is a key indicator in understanding and representing an environment's overall health. Through developments in remote sensing, we can utilize satellite imagery to measure water parameters in each aquatic system. When accurate atmospheric correction is performed, remote sensing can account for atmospheric attenuation and scattering effects to better measure the reflectance and estimate optically active constituents (OAC) present in upper water columns. Atmospheric Correction for OLI lite (ACOLITE) is an atmospheric correction algorithm designed specifically for robust atmospheric correction of water surfaces, in comparison to algorithms designed more for land surfaces such as the European Space Agency’s (ESA) Sen2Cor. An evaluation of atmospheric correction methods for coastal water quality for Georgia, USA, where contributions from pigments, inorganic matter, and organic matter are quite variable, has not been performed. This project analyzes the application and accuracy of atmospheric correction methods for several Georgia estuaries with spatially and temporally variable concentrations of water quality constituents using satellite imagery, in situ close-range spectral reflectance remote sensing match-up data, and field and laboratory analysis of water variables. The objectives of this study are: (1) Characterize study sites and individual water samples based on their concentrations of chlorophyll-a pigments, inorganic matter, and color-

dissolved organic matter based on hyperspectral close-range reflectance, multispectral Sentinel-2 MultiSpectral Instrument (MSI) reflectance, and analysis bulk water samples and; (2) Evaluate and compare the accuracy of spectral reflectance data with no atmospheric correction, and ACOLITE and Sen2Cor atmospheric correction algorithms. It was found that hierarchical clustering had inconclusive results at characterizing optical water types, and some variation in optical water types were even seen within study sites. Further, ACOLITE and Sen2Cor atmospheric correction algorithms performed comparably at each specific wavelength in these environments (ACOLITE R²=0.215 (band 5) to 0.33 (band 2), Sen2cor R²=0.061 (band 5) to 0.299 (band 3)), and further validation would be required for a deeper understanding of their performance on more than a band-to-band comparison.

Research Data and Supplementary Material

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