Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 11 5 2007 10.5194/hess-11-1543-2007 http://www.hydrol-earth-syst-sci.net/11/1543/2007/ http://www.hydrol-earth-syst-sci.net/11/1543/2007/hess-11-1543-2007.html http://www.hydrol-earth-syst-sci.net/11/1543/2007/hess-11-1543-2007.pdf 1543 1550 2007-09-06 Modelling the spatial variability of snow water equivalent at the catchment scale T. Skaugen ths@nve.no Norwegian Water Resources and Energy Directorate, P.O. Box 5091, Maj, 0301, Oslo, Norway Department of Geosciences, University of Oslo, P.O. Box 1047, Blindern, Oslo, Norway The spatial distribution of snow water equivalent (SWE) is modelled as a two parameter gamma distribution. The parameters of the distribution are dynamical in that they are functions of the number of accumulation and melting events and the temporal correlation of accumulation and melting events. The estimated spatial variability is compared to snow course observations from the alpine catchments Norefjell and Aursunden in Southern Norway. A fixed snow course at Norefjell was measured 26 times during the snow season and showed that the spatial coefficient of variation change during the snow season with a decreasing trend from the start of the accumulation period and a sharp increase in the melting period. The gamma distribution with dynamical parameters reproduced the observed spatial statistical features of SWE well both at Norefjell and Aursunden. Also the shape of simulated spatial distribution of SWE agreed well with the observed at Norefjell. The temporal correlation tends to be positive for both accumulation and melting events. However, at the start of melting, a better fit between modelled and observed spatial standard deviation of SWE is obtained by using negative correlation between SWE and melt. Alfnes, E., Andreassen, L. M., Engeset, R. 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