Near Realtime Snow Covered Area Mapping with Envisat Asar Wideswath in Norwegian Mountaineous Areas

A near-real time GMES-relevant monitoring system for semi-operational retrieval of snow covered area for hydrological and climatological applications has been developed in the Envisnow EC EESD FP 5 project. The system, using ENVISAT ASAR wide swath data from ESA AOE 785 and from the Kongsberg satellite station, geocodes and classifies Envisat ASAR data automatically, and produces SCA maps with confidence flags. The snow covered area maps are used in hydrological models in Norway to improve run-off forecasting and flood warnings. We show that Envisat ASAR wide swath data can be used to produce snow cover maps with 100 m resolution and 500 km by 500 km coverage. This allows semioperational use of SAR data for regional and maybe global snow mapping. The applied wet snow detection algorithm (Nagler and Rott, 2000) has been complimented with a dry snow algorithm, predicting dry snow above medium wet snow line. Results and accuracy assessments from campaigns in southern Norway in 2003 and 2004 will be shown. Results from a near-real time multi-sensor demonstration of the system in 2004 will also be shown. Snow cover; SAR;Near real time;GMES;Hydrology