Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/21140
Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: Validation of Envisat MERIS algorithms for chlorophyll retrieval in a large, turbid and optically-complex shallow lake
Authors: Palmer, Stephanie
Hunter, Peter
Lankester, Thomas
Hubbard, Steven
Spyrakos, Evangelos
Tyler, Andrew
Presing, Matyas
Horvath, Hajnalka
Lamb, Alistair
Balzter, Heiko
Toth, Victor
Contact Email: p.d.hunter@stir.ac.uk
Keywords: MERIS
Chlorophyll-a
Inland waters
Validation
Lake Balaton
Algorithm
Issue Date: Feb-2015
Publisher: Elsevier
Citation: Palmer S, Hunter P, Lankester T, Hubbard S, Spyrakos E, Tyler A, Presing M, Horvath H, Lamb A, Balzter H & Toth V (2015) Validation of Envisat MERIS algorithms for chlorophyll retrieval in a large, turbid and optically-complex shallow lake, Remote Sensing of Environment, 157, pp. 158-169.
Abstract: The 10-year archive of MEdium Resolution Imaging Spectrometer (MERIS) data is an invaluable resource for studies on lake system dynamics at regional and global scales. MERIS data are no longer actively acquired but their capacity for global scale monitoring of lakes from satellites will soon be re-established through the forthcoming Sentinel-3 Ocean and Land Colour Instrument (OLCI). The development and validation of in-water algorithms for the accurate retrieval of biogeochemical parameters is thus of key importance if the potential of MERIS and OLCI data is to be fully exploited for lake monitoring. This study presents the first extensive validation of algorithms for chlorophyll-a (chl-a) retrieval by MERIS in the highly turbid and productive waters of Lake Balaton, Hungary. Six algorithms for chl-a retrieval from MERIS over optically complex Case 2 waters, including band-difference and neural network architectures, were compared using the MERIS archive for 2007-2012. The algorithms were locally-tuned and validated using in situ chl-a data (n = 289) spanning the five year processed image time series and from all four lake basins. In general, both band-difference algorithms tested (Fluorescence Line Height (FLH) and Maximum Chlorophyll Index (MCI)) performed well, whereas the neural network processors were generally found to much less accurately retrieve in situ chl-a concentrations. The Level 1b FLH algorithm performed best overall in terms of chl-a retrieval (R2 = 0.87; RMSE = 4.19 mg m - 3; relative RMSE = 30.75%) and particularly at chl-a concentrations of ≥ 10 mg m- 3 (R2 = 0.85; RMSE = 4.81 mg m- 3; relative RMSE = 20.77%). However, under mesotrophic conditions (i.e., chl-a < 10 mg m- 3) FLH was outperformed by the locally-tuned FUB/WeW processor (relative FLH RMSE < 10 mg m- 3 = 57.57% versus relative FUB/WeW RMSE < 10 mg m- 3 = 46.96%). An ensemble selection of in-water algorithms is demonstrated to improve chl-a retrievals.
Type: Journal Article
URI: http://hdl.handle.net/1893/21140
DOI Link: http://dx.doi.org/10.1016/j.rse.2014.07.024
Rights: © 2014 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/).
Affiliation: University of Leicester
Biological and Environmental Sciences
Airbus Defence and Space
Airbus Defence and Space
Biological and Environmental Sciences
Biological and Environmental Sciences
Hungarian Academy of Sciences
Hungarian Academy of Sciences
Airbus Defence and Space
University of Leicester
Hungarian Academy of Sciences

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