A satellite-based climatology of European alpine lake surface water temperature for the period 1989–2013

Abstract:

Lake water temperature (LWT) is an important driver of lake ecosystems and it has been identified as an indicator of climate change. At some European lakes LWT has been observed over several decades, but the majority of lakes is not monitored, or only on a non-regular basis, which is insufficient to track a climate signal. Satellite observations might be utilized to fill these gaps, however, only few satellite sensors offer the possibility to analyze time series which cover 25 years or more. The Advanced Very High Resolution Radiometer (AVHRR) is among these and has been flown as a heritage instrument for almost 35 years. It will be carried on for at least ten more years finally offering a unique opportunity for satellite-based climate studies.

We present a satellite-based lake surface water temperature (LSWT) data set for European (pre-alpine) water bodies based on the extensive AVHRR 1 km data record (1989–2013) of the Remote Sensing Research Group at the University of Bern, Switzerland. It has been compiled out of AVHRR/2 (NOAA-07, -09, -11, -14) and AVHRR/3 (NOAA-16, -17, -18, -19 and Metop-A) day and night time data. We will discuss the processing steps (e.g. geolocation, calibration, LSWT algorithm, etc.) which are necessary to obtain the accuracy needed for climate related studies. The resulting climatology covers pre-alpine and alpine lakes with sizes between 14 and 580 km². We will present and discuss the analysis of trends for some sample lakes in various regions of the Alps.