MODIS-derived Spatiotemporal Water Clarity Patterns in Optically Shallow Florida Keys Waters: A New Approach to Remove Bottom Contamination

Brian B. Barnes; Chuanmin Hu; Blake A. Schaeffer; Zhongping Lee; David A. Palandro; John C. Lehrter

doi:10.1016/j.rse.2013.03.016

MODIS-derived Spatiotemporal Water Clarity Patterns in Optically Shallow Florida Keys Waters: A New Approach to Remove Bottom Contamination

Brian B. Barnes, Chuanmin Hu, Blake A. Schaeffer, Zhongping Lee, David A. Palandro, John C. Lehrter

College of Marine Science

Research output: Contribution to journal › Article › peer-review

Abstract

Retrievals of water quality parameters from satellite measurements over optically shallow waters have been problematic due to bottom contamination of the signals. As a result, large errors are associated with derived water column properties. These deficiencies greatly reduce the ability to use satellites to assess the shallow water environments around coral reefs and <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/seagrass-bed" title="Learn more about Seagrass Bed from ScienceDirect's AI-generated Topic Pages"> seagrass beds </a> . Here, a modified version of an existing algorithm is used to derive multispectral diffuse <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/attenuation-coefficient" title="Learn more about Attenuation Coefficient from ScienceDirect's AI-generated Topic Pages"> attenuation coefficient </a> (K d ) from MODIS/Aqua measurements over optically shallow waters in the Florida Keys. Results were validated against concurrent in situ data (K d (488) from 0.02 to 0.20 m− 1, N = 22, R 2 = 0.68, Mean Ratio = 0.93, unbiased RMS = 31%), and showed significant improvement over current products when compared to the same in situ data (N = 13, R 2 = 0.37, Mean Ratio = 1.61, unbiased RMS = 50%). The modified algorithm was then applied to time series of MODIS/Aqua data over the Florida Keys (in particular, the Florida Keys Reef Tract), whereby spatial and temporal patterns of water clarity between 2002 and 2011 were elucidated. Climatologies, time series, anomaly images, and <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/empirical-orthogonal-function-analysis" title="Learn more about Empirical Orthogonal Function Analysis from ScienceDirect's AI-generated Topic Pages"> empirical orthogonal function analysis </a> showed primarily nearshore–offshore gradients in water clarity and its variability, with peaks in both at the major channels draining Florida Bay. ANOVA revealed significant differences in K d (488) according to distance from shore and geographic region. Excluding the Dry Tortugas, which had the lowest climatological K d (488), water was clearest at the northern extent of the Reef Tract, and K d (488) significantly decreased sequentially for every region along the tract. Tests over other shallow-water tropical waters such as the Belize <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/barrier-reef" title="Learn more about Barrier Reef from ScienceDirect's AI-generated Topic Pages"> Barrier Reef </a> also suggested general applicability of the algorithm. As water clarity and light availability on the ocean bottom are key environmental parameters in determining the health of shallow-water plants and animals, the validated new products provide unprecedented information for assessing and monitoring of coral reef and <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/sea-grasses" title="Learn more about Sea Grasses from ScienceDirect's AI-generated Topic Pages"> seagrass </a> health, and could further assist ongoing regional zoning efforts.

Original language	American English
Journal	Remote Sensing of Environment
Volume	134
DOIs	https://doi.org/10.1016/j.rse.2013.03.016
State	Published - Jul 1 2013

Keywords

Ocean color
Optically shallow water
Water clarity

Disciplines

Life Sciences

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10.1016/j.rse.2013.03.016License: CC BY

https://doi.org/10.1016/j.rse.2013.03.016

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@article{5f93f264813b43d0a05fa69a4c2f4e0e,

title = "MODIS-derived Spatiotemporal Water Clarity Patterns in Optically Shallow Florida Keys Waters: A New Approach to Remove Bottom Contamination",

abstract = " Retrievals of water quality parameters from satellite measurements over optically shallow waters have been problematic due to bottom contamination of the signals. As a result, large errors are associated with derived water column properties. These deficiencies greatly reduce the ability to use satellites to assess the shallow water environments around coral reefs and seagrass beds . Here, a modified version of an existing algorithm is used to derive multispectral diffuse attenuation coefficient (K d ) from MODIS/Aqua measurements over optically shallow waters in the Florida Keys. Results were validated against concurrent in situ data (K d (488) from 0.02 to 0.20 m− 1, N = 22, R 2 = 0.68, Mean Ratio = 0.93, unbiased RMS = 31%), and showed significant improvement over current products when compared to the same in situ data (N = 13, R 2 = 0.37, Mean Ratio = 1.61, unbiased RMS = 50%). The modified algorithm was then applied to time series of MODIS/Aqua data over the Florida Keys (in particular, the Florida Keys Reef Tract), whereby spatial and temporal patterns of water clarity between 2002 and 2011 were elucidated. Climatologies, time series, anomaly images, and empirical orthogonal function analysis showed primarily nearshore–offshore gradients in water clarity and its variability, with peaks in both at the major channels draining Florida Bay. ANOVA revealed significant differences in K d (488) according to distance from shore and geographic region. Excluding the Dry Tortugas, which had the lowest climatological K d (488), water was clearest at the northern extent of the Reef Tract, and K d (488) significantly decreased sequentially for every region along the tract. Tests over other shallow-water tropical waters such as the Belize Barrier Reef also suggested general applicability of the algorithm. As water clarity and light availability on the ocean bottom are key environmental parameters in determining the health of shallow-water plants and animals, the validated new products provide unprecedented information for assessing and monitoring of coral reef and seagrass health, and could further assist ongoing regional zoning efforts. ",

keywords = "Ocean color, Optically shallow water, Water clarity",

author = "Barnes, {Brian B.} and Chuanmin Hu and Schaeffer, {Blake A.} and Zhongping Lee and Palandro, {David A.} and Lehrter, {John C.}",

year = "2013",

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day = "1",

doi = "10.1016/j.rse.2013.03.016",

language = "American English",

volume = "134",

journal = "Remote Sensing of Environment",

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TY - JOUR

T1 - MODIS-derived Spatiotemporal Water Clarity Patterns in Optically Shallow Florida Keys Waters: A New Approach to Remove Bottom Contamination

AU - Barnes, Brian B.

AU - Hu, Chuanmin

AU - Schaeffer, Blake A.

AU - Lee, Zhongping

AU - Palandro, David A.

AU - Lehrter, John C.

PY - 2013/7/1

Y1 - 2013/7/1

N2 - Retrievals of water quality parameters from satellite measurements over optically shallow waters have been problematic due to bottom contamination of the signals. As a result, large errors are associated with derived water column properties. These deficiencies greatly reduce the ability to use satellites to assess the shallow water environments around coral reefs and seagrass beds . Here, a modified version of an existing algorithm is used to derive multispectral diffuse attenuation coefficient (K d ) from MODIS/Aqua measurements over optically shallow waters in the Florida Keys. Results were validated against concurrent in situ data (K d (488) from 0.02 to 0.20 m− 1, N = 22, R 2 = 0.68, Mean Ratio = 0.93, unbiased RMS = 31%), and showed significant improvement over current products when compared to the same in situ data (N = 13, R 2 = 0.37, Mean Ratio = 1.61, unbiased RMS = 50%). The modified algorithm was then applied to time series of MODIS/Aqua data over the Florida Keys (in particular, the Florida Keys Reef Tract), whereby spatial and temporal patterns of water clarity between 2002 and 2011 were elucidated. Climatologies, time series, anomaly images, and empirical orthogonal function analysis showed primarily nearshore–offshore gradients in water clarity and its variability, with peaks in both at the major channels draining Florida Bay. ANOVA revealed significant differences in K d (488) according to distance from shore and geographic region. Excluding the Dry Tortugas, which had the lowest climatological K d (488), water was clearest at the northern extent of the Reef Tract, and K d (488) significantly decreased sequentially for every region along the tract. Tests over other shallow-water tropical waters such as the Belize Barrier Reef also suggested general applicability of the algorithm. As water clarity and light availability on the ocean bottom are key environmental parameters in determining the health of shallow-water plants and animals, the validated new products provide unprecedented information for assessing and monitoring of coral reef and seagrass health, and could further assist ongoing regional zoning efforts.

AB - Retrievals of water quality parameters from satellite measurements over optically shallow waters have been problematic due to bottom contamination of the signals. As a result, large errors are associated with derived water column properties. These deficiencies greatly reduce the ability to use satellites to assess the shallow water environments around coral reefs and seagrass beds . Here, a modified version of an existing algorithm is used to derive multispectral diffuse attenuation coefficient (K d ) from MODIS/Aqua measurements over optically shallow waters in the Florida Keys. Results were validated against concurrent in situ data (K d (488) from 0.02 to 0.20 m− 1, N = 22, R 2 = 0.68, Mean Ratio = 0.93, unbiased RMS = 31%), and showed significant improvement over current products when compared to the same in situ data (N = 13, R 2 = 0.37, Mean Ratio = 1.61, unbiased RMS = 50%). The modified algorithm was then applied to time series of MODIS/Aqua data over the Florida Keys (in particular, the Florida Keys Reef Tract), whereby spatial and temporal patterns of water clarity between 2002 and 2011 were elucidated. Climatologies, time series, anomaly images, and empirical orthogonal function analysis showed primarily nearshore–offshore gradients in water clarity and its variability, with peaks in both at the major channels draining Florida Bay. ANOVA revealed significant differences in K d (488) according to distance from shore and geographic region. Excluding the Dry Tortugas, which had the lowest climatological K d (488), water was clearest at the northern extent of the Reef Tract, and K d (488) significantly decreased sequentially for every region along the tract. Tests over other shallow-water tropical waters such as the Belize Barrier Reef also suggested general applicability of the algorithm. As water clarity and light availability on the ocean bottom are key environmental parameters in determining the health of shallow-water plants and animals, the validated new products provide unprecedented information for assessing and monitoring of coral reef and seagrass health, and could further assist ongoing regional zoning efforts.

KW - Ocean color

KW - Optically shallow water

KW - Water clarity

UR - https://digitalcommons.usf.edu/msc_facpub/1919

UR - https://doi.org/10.1016/j.rse.2013.03.016

U2 - 10.1016/j.rse.2013.03.016

DO - 10.1016/j.rse.2013.03.016

M3 - Article

VL - 134

JO - Remote Sensing of Environment

JF - Remote Sensing of Environment

ER -

MODIS-derived Spatiotemporal Water Clarity Patterns in Optically Shallow Florida Keys Waters: A New Approach to Remove Bottom Contamination

Abstract

Keywords

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