Can a Point Measurement Represent the Snow Depth in its Vicinity? A Comparison of Areal Snow Depth Measurements With Selected Index Sites

Information on the amount of snow stored in a catchment or on a mountain is an impor- tant issue for hydrology, natural hazards, winter tourism or mountain ecology. Area-wide measure- ments of the snow depth in an appropriate spatial and temporal resolution are usually not available as they are costly and difficult to obtain. In practice one often relies on few, selected point measurements, like meteorological stations which measure snow depth at a specific location in a high temporal resolu- tion and one assumes that these index sites represent the snow cover of their vicinity. Such index sites are usually located in flat and sheltered terrain and it has been questioned if such places are really capable to represent the snow cover of their larger surrounding. In this study we use a large data set of areal snow depth measurements obtained by airborne laser scanning in different mountain regions and analyse, if virtual index-sites within the study areas do represent the real snow distribution of their direct vicinity and of the entire catchment. We show that single stations are not able to repre- sent the snow cover and that most stations tend to clearly overestimate snow depth. There are, how- ever, also index sites which measure lower snow depths than the surrounding area. Such stations are typically dominated by strong winds. We also show that elevation gradients of snow depth are qualita- tively captured by index sites, even though quantitative estimation of real gradients using index sites has a large error.