Water Quality Monitoring by Satellite

Abstract

To establish and maintain certain water quality standards, effective control methods of water parameters are of high importance. Eutrophication and annual phytoplankton blooms play an important role in areas with a strong anthropogenic influence, such as the Baltic Sea. Annual mass growth of phytoplankton and the subsequent biomass, causes several problems for ma-rine life and the matter budget. Cyanobacteria is capable of fixing atmospheric nitrogen and thereby adds to the already dominant problem of eutrophication and threatens other marine organisms with its capability of producing toxins. These cyanotoxins can even affect human beings directly or indirectly through the food chain. Solid knowledge about the place and extent of these blooms as well as interannual variability is very important for understanding and improving the ecological situation. In Situ measurements in wide aquatic areas are time-consuming and expensive, yet only give spatially and temporally limited information whereas satellite remote sensing offers monitoring of bio-optical parameters with a high spatial and temporal resolution. Over the past years, the Marine Remote Sensing Group at the German Aerospace Center has developed different methods for the derivation of water constituent parameters from spectral satellite sensor data. Besides todays standard parameters for chlorophyll, suspended matter and gelbstoff, novel approaches for important parameters like water transparency and cyanobacteria specific pigments were taken. A new neural-network-based algorithm addressing the specific optical properties of cyanobacteria in the Baltic Sea was developed. The algorithms were developed for the MERIS sensor and will be adjustable to the OLCI instrument aboard the coming SENTINEL-3 mission. Besides the development of new methods, InSitu-measurements of important optical properties above and beneath the water surface are another expertise of the workgroup, based in Berlin- Adlershof. These measurements are needed for validation and improvement of existing algorithms as well as the development of new algorithms. The Poster will give an overview over the current algorithms and results.