QUANTITATIVE DETECTION OF CYANOBACTERIAL BLOOMS BY OCEAN COLOUR SENSORS*

摘要

Potentially toxic cyanobacterial blooms occur in the middle of summer in the Baltic Sea. Depending from nutrient availability and local hydro-meteorological conditions chlorophyll concentration increases from 1-4 mg/m-3 up to hundreds mg/m-3. Aggregations of cyanobacteria form often dense subsurface blooms or even surface scum, which are spatially extremely patchy. Use of remote sensing is hampered because of failure standard atmospheric correction procedures and water quality algorithms of common ocean color sensors during cyanobacterial blooms. It is possibly caused by very high (up to 50%) reflectance in near-infrared part of spectrum in the areas where concentrations of cyanobacteria are very high. SeaWiFS, MODIS and MERIS standards products over heavy bloom region are compared with each other and with results of bio-optical modeling to study suitability of these sensors for quantitative detection of cyanobacterial blooms. For comparisons results obtained by sensors with better spatial and spectral resolution (Hyperion) were used.