Calibration of MODIS satellite images and chlorophyll-a mapping for the Baltic Sea

Seppo Kaitala, Jukka Seppälä, Pasi Ylöstalo
Finnish Institute of Marine Research
PO Box 33, Helsinki, FIN-0091, Finland
Seppo.Kaitala@Fimr.Fi

ABSTRACT

Conventionally, chlorophyll-a estimates are obtained using empirical reflectance ratios. In the case of the Baltic Sea high concentrations of coloured dissolved organic matter (CDOM) and high turbidity due to high contents of suspended matter make the predictions more difficult. In these multi-component cases more complex hyperspectral models are needed. For that purpose multivariate calibration was applied to validate Modis satellite data against automated fluorescence records of chlorophyll-a on board the ferry Finnpartner with a regular route from Travemünde to Helsinki (Alg@line data).

Partial least square (PLS) regression analysis was used to validate chlorophyll-a records against 1 km resolution bands. Also a feasibility study was carried out to use phycocyanin fluorescence to detect cyanobacteria blooms.

Multispectral absorption properties of laboratory cultures of common phytoplankton species were investigated with PLS analysis to compare with spectral signature of satellite images for possible species recognition. Multivariate calibration methods seem to be superior to univariate methods for algorithm development of satellite image analysis in the case of turbid coastal waters.

Last Update: 2005-03-16