Water

Water quality 

When sunlight penetrates water surfaces, it is scattered and absorbed by constituents that determine the water’s natural color. The color of a lake as seen by a satellite can thus be used to retrieve the constituent concentrations in the surface layer, as well as their horizontal variation. In this respect, remote sensing is an ideal complement to local in situ profile measurements. The feasibility of combining in situ and remotely sensed monitoring has been demonstrated by RSL (University of Zurich) with chlorophyll data from official water quality measurements in perialpine lakes (Odermatt et al., 2010).

Water quality
When sunlight penetrates water surfaces, it is scattered and absorbed by constituents that determine the water’s natural color. The color of a lake as seen by a satellite can thus be used to retrieve the constituent concentrations in the surface layer, as well as their horizontal variation. In this respect, remote sensing is an ideal complement to local in situ profile measurements. The feasibility of combining in situ and remotely sensed monitoring has been demonstrated by RSL (University of Zurich) with chlorophyll data from official water quality measurements in perialpine lakes (Odermatt et al., 2010 External website. Content opens in new window)


Lake surface temperature 

The surface temperature of lakes can be used as a proxy for climate warming. In some regions of the world the water body temperatures show a pronounced increase which exceeds the air temperature over land (Schneider and Hook, 2010). As such, lake surface temperature (LST) is defined as an Essential Climate Variable by GCOS to support UNFCCC and IPCC. The aim of a project at the University of Bern’s Remote Sensing Group is to process and analyze AVHRR data from 1989 – 2010 to derive LST for a large set of sufficiently large lakes. The final data set will be available for other groups on behalf of GCOS Switzerland.

Surface temperature of Lake Geneva
Surface temperature of Lake Geneva, acquired on February 21, 2012. Corresponding data is available through the saturn portal (image by RSGB/NOAA).