Validation of satellite data for quality assurance in lake monitoring applications

This paper focuses on importance of radiometric corrections for an operational use of EO technologies to lake water quality monitoring. Fundamental elements in this quality assurance framework are sensor calibration and atmospheric correction, which are briefly discussed in the paper. In order to evaluate the accuracy of present operational techniques to retrieve basic parameters from satellite data, such as water-leaving radiance and reflectance, an experiment was organised in the frame of an EU co-funded RTD project. A series of ship-based radiometric and atmospheric measuring campaigns were conducted on Lake Iseo and Lake Garda (Italy) together with limnological sampling. Four Landsat-5 TM scenes were acquired during different seasons and simultaneous in situ measurements were made. After the radiometric calibration procedure, satellite digital images were processed by applying different image-based atmospheric correction models. The results achieved using these procedures were evaluated by comparing satellite-based estimates with in situ measurements of water reflectance.