Comparison of satellite chlorophyll a algorithms for the Baltic Sea

Abstract

Chlorophyll a (chl-a) products calculated using medium resolution imaging spec- trometer (MERIS) data were tested. The satellite products were compared to chl-a concentra- tions measured in surface waters between 2003 and 2011 throughout the Baltic Sea. Image processing was performed with two neural-network-based MERIS data processors: the Case- 2 Water Properties processor developed at the Freie Universitat Berlin (FUB) and the Case- 2 Regional processor of the German Institute for Coastal Research (C2R). Additionally, two algorithms for deriving chl-a concentrations from atmospherically corrected reflectances origi- nally designed for Moderate Resolution Imaging Spectroradiometer and Sea-viewing Wide Field-of-view Sensor radiometers and adapted to Baltic Sea conditions were tested (algorithms denoted further as MD and SW respectively). The effectiveness of the Improved Contrast between Ocean and Land (ICOL) processor was also verified. Our results showed that the accu- racy of chl-a concentration retrieval from satellite data varies depending on the location of the area. The difference in the statistical error between results from optically different coastal and open sea waters was as high as 200%. The most accurate results for the coastal zone were noted for the standard chl-a FUB processor product, while in open sea waters the highest accuracy was noted for the MD and SW algorithms with reflectance derived from the FUB processor. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10.1117/1.JRS.8.083605)