Long term trend of snow depth at Sonnblick (Austrian Alps) and its relation to climate change

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Abstract

The extensive snow measurement network of the Sonnblick region (Hohe Tauern, Austrian Alps) is used to describe temporal trends of snow-depth as well as its relation to climate change for a high-elevated site of the European Alps (2400–3100 m.a.s.l.). Spatial representativeness of single snow stakes, with readings back to 1928, is derived for maximum snow-depth in May using a spatially dense snow depth probing from glacier mass balance measurements. Long-term trends of snow depth show a significant reduction in the contribution of snow accumulation from core-winter (1 December to 1 March) compared to early and late-winter periods. Largest values of snow-depth since 1928 were measured in the 1940s and 1950s. Comparison of monthly changes in snow-depth with precipitation measurements underlines the high influence of wind drift on snow-depth during winter season from 1 October to 30 April. Whereas inter-annual variability of maximum snow-depth is better explained by low elevation precipitation measurements than by local (high elevation) precipitation measurements, the longer-term mean of local precipitation measurements, however, fits well to the snow-depth measurements, if a mean snow-density of about 400 kg m−3 is assumed (which matches field observations). Both maximum snow-depth and winter season precipitation show a clear decreasing trend for inter-annual variability. A statistical relationship between air temperature and fraction of solid precipitation is used for estimation of temporal trends in the fraction of solid precipitation at measurement sites. For summer a decrease of about 1% of solid precipitation per decade was found for the lowest elevated sites whereas fraction of solid precipitation in winter remains stable. Relation between snow-depth and climate is investigated by means of local climate data of Sonnblick-Observatory (SBO) and by means of the North-Atlantic Oscillation Index (NAOI). Whereas winter air-temperature is significantly correlated with the NAOI, for winter precipitation and snow depth on 1 May no correlation was found with NAOI. Copyright © 2008 John Wiley & Sons, Ltd.

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