Remote sensing and radiative transfer in shallow inland waters: investigations at Lake Constance

Abstract

Shallow water areas offer highly spatial and temporal dynamics and variable boundary conditions for biological, chemical and physical processes. With remote sensing instruments on aircrafts, and perhaps in future on satellites, it is possible to observe extended areas with a spatial resolution in the meter range. Airborne sensors offer high temporal resolution. Different remote sensing techniques with optical multispectral sensors allow to determine the concentration and distribution of water constituents such as phytoplankton, suspended sediments, dissolved organic matter etc. This has been done for deep water but not yet for shallow water areas, where the detected light is remarkably influenced also by the reflectance of the bottom and thus has to be taken into consideration in a radiative transfer model for the water body. The classification of bottom surfaces into several groups is a subject of research. Underwater measurements of the light field are performed together with measurements of the optical properties of water constituents and the different bottom types. These measurements are then compared with results of radiative transfer models.