Analyses of seasonal snow disappearance in an alpine valley from micro- to meso-scale (Loetschental, Switzerland)

The seasonal snow cover duration depends on climatic conditions, vegetation and topography. Conventional approaches of snow cover monitoring, based on point measurements or remote sensing techniques, are not suitable for meso-scale spatial and temporal observations, or for analyses of the snow extent. However, these meso-scale analyses are the basis for an understanding of ecological, hydrological and climatic systems in high mountains. Therefore, new approaches are required to monitor and to analyse the meso-scale spatial snow cover distribution. In the presented study, we used 30 point measurement data and terrestrial images, which were taken by two digital cameras. The micro-scale point measurements show the snow cover duration in several topographical positions. The terrestrial images monitor the variation of snow extent on a northwest and southeast-facing slope. They provide a spatial resolution of 10 ill, and due to bad weather conditions, a temporal resolution of 5 days. Both, the micro- as well as meso-scale data enabled statistical analyses of the impact of topography on snow cover duration. The combination of terrestrial images and point measurements facilitated the verification of the representativeness of point measurements as well as their extrapolation capabilities. One important conclusion of the presented study is that snow cover duration can be explained just partly by topographical features. Copyright (C) 2008 John Wiley & Sons, Ltd.