A semi-operative approach to lake water quality retrieval from remote sensing data

A semi-operative approach to retrieve chlorophyll-a concentration from airb orne/spaceborne spectrometer observations has been developed and tested usi ng the airborne imaging spectrometer (AISA) data from 11 lakes located in s outhern Finland. The retrieval approach is empirical and requires nearly si multaneous in situ training data on water quality for the determination of regression coefficients. However, the training data does not have to be col lected from every lake under investigation. Instead, the results obtained i ndicate that reliable estimates on the level of chlorophyll-a (chl-a) for a n individual lake can be achieved without employing in situ data representi ng this specific lake. This enables the estimation of water quality from re motely sensed data for numerous lakes with the aid of reference data only f or a few selected lakes representing the region under investigation. In add ition, it is shown that the remotely sensed spectrum shape characteristics are highly affected by the trophic and humic state of the lake water. (C) 2 001 Elsevier Science B.V. All rights reserved.