Improved red-edge chlorophyll-a detection for Sentinel 2

Chlorophyll-a (chl-a) concentration is an indicator of algal biomass. The Sentinel 2 platform offers greatly improved spatial resolution over other satellite platforms designed for water based chl-a retrievals and includes a “red-edge” band at 704 nm not present on the Landsat 8 operational land ima...

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Autores principales: James Bramich, Christopher J.S. Bolch, Andrew Fischer
Formato: article
Lenguaje:EN
Publicado: Elsevier 2021
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Acceso en línea:https://doaj.org/article/6e60ad27db5a4877bd2be224cd1af407
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spelling oai:doaj.org-article:6e60ad27db5a4877bd2be224cd1af4072021-12-01T04:28:09ZImproved red-edge chlorophyll-a detection for Sentinel 21470-160X10.1016/j.ecolind.2020.106876https://doaj.org/article/6e60ad27db5a4877bd2be224cd1af4072021-01-01T00:00:00Zhttp://www.sciencedirect.com/science/article/pii/S1470160X20308141https://doaj.org/toc/1470-160XChlorophyll-a (chl-a) concentration is an indicator of algal biomass. The Sentinel 2 platform offers greatly improved spatial resolution over other satellite platforms designed for water based chl-a retrievals and includes a “red-edge” band at 704 nm not present on the Landsat 8 operational land imager. This study provides validation of an improved version of a well known semi-analytical chl-a retrieval algorithm. The algorithm is provided with several free image processing utilities and the improved approach can be implemented with minimal technology skills. The improved performance is the result of replacing a fixed chl-a specific absorption coefficient (a*) with a variable model. This method was applied to three Sentinel 2 images taken over the Lake Erie western basin correlating with an in-situ dataset of 24 samples where chl-a ranged from 1.89 mg m−3 to 70.20 mg m−3. The variable a* model produced chl-a retrievals with normalised root mean squared error of prediction (NRMSEP) = 7.5%, bias = -0.47 mg m−3, coefficient of determination (R2) = 0.91 and Nash-Sutcliffe efficiency (NSE) = 0.90). This represented a 23% reduction in NRMSEP, an 85% reduction in bias and an increase in NSE of 7% over the default algorithm using a fixed a* value. Creation of chl-a retrieval algorithms that consider the variability in a* should result in algorithms that perform better against a wide range of chl-a concentrations and are less likely to require local recalibration. Obtaining accurate chl-a retrievals from a satellite platform with the spatial resolution of Sentinel 2 will allow satellite monitoring of many more inland waters than previously possible.James BramichChristopher J.S. BolchAndrew FischerElsevierarticleRemote sensingChlorophyll-aSentinel 2MSIRed-edgeEcologyQH540-549.5ENEcological Indicators, Vol 120, Iss , Pp 106876- (2021)
institution DOAJ
collection DOAJ
language EN
topic Remote sensing
Chlorophyll-a
Sentinel 2
MSI
Red-edge
Ecology
QH540-549.5
spellingShingle Remote sensing
Chlorophyll-a
Sentinel 2
MSI
Red-edge
Ecology
QH540-549.5
James Bramich
Christopher J.S. Bolch
Andrew Fischer
Improved red-edge chlorophyll-a detection for Sentinel 2
description Chlorophyll-a (chl-a) concentration is an indicator of algal biomass. The Sentinel 2 platform offers greatly improved spatial resolution over other satellite platforms designed for water based chl-a retrievals and includes a “red-edge” band at 704 nm not present on the Landsat 8 operational land imager. This study provides validation of an improved version of a well known semi-analytical chl-a retrieval algorithm. The algorithm is provided with several free image processing utilities and the improved approach can be implemented with minimal technology skills. The improved performance is the result of replacing a fixed chl-a specific absorption coefficient (a*) with a variable model. This method was applied to three Sentinel 2 images taken over the Lake Erie western basin correlating with an in-situ dataset of 24 samples where chl-a ranged from 1.89 mg m−3 to 70.20 mg m−3. The variable a* model produced chl-a retrievals with normalised root mean squared error of prediction (NRMSEP) = 7.5%, bias = -0.47 mg m−3, coefficient of determination (R2) = 0.91 and Nash-Sutcliffe efficiency (NSE) = 0.90). This represented a 23% reduction in NRMSEP, an 85% reduction in bias and an increase in NSE of 7% over the default algorithm using a fixed a* value. Creation of chl-a retrieval algorithms that consider the variability in a* should result in algorithms that perform better against a wide range of chl-a concentrations and are less likely to require local recalibration. Obtaining accurate chl-a retrievals from a satellite platform with the spatial resolution of Sentinel 2 will allow satellite monitoring of many more inland waters than previously possible.
format article
author James Bramich
Christopher J.S. Bolch
Andrew Fischer
author_facet James Bramich
Christopher J.S. Bolch
Andrew Fischer
author_sort James Bramich
title Improved red-edge chlorophyll-a detection for Sentinel 2
title_short Improved red-edge chlorophyll-a detection for Sentinel 2
title_full Improved red-edge chlorophyll-a detection for Sentinel 2
title_fullStr Improved red-edge chlorophyll-a detection for Sentinel 2
title_full_unstemmed Improved red-edge chlorophyll-a detection for Sentinel 2
title_sort improved red-edge chlorophyll-a detection for sentinel 2
publisher Elsevier
publishDate 2021
url https://doaj.org/article/6e60ad27db5a4877bd2be224cd1af407
work_keys_str_mv AT jamesbramich improvedrededgechlorophylladetectionforsentinel2
AT christopherjsbolch improvedrededgechlorophylladetectionforsentinel2
AT andrewfischer improvedrededgechlorophylladetectionforsentinel2
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