A Statistical Analysis of Snow Depth Variability in Norway and Evaluation of Norwegian Snow Maps

• Main Author: Dyrrdal, Anita Verpe
• Other Authors: Gary M. Lackmann, Committee Member, John F. Monahan, Committee Member, Frederick H.M. Semazzi, Committee Chair
• Language: unknown
• Published: 2009
• Subjects: snow depth; Norway; statistical anlysis; snow; maps; norwegian snow maps; Arctic; Global warming
• Online Access: http://www.lib.ncsu.edu/resolver/1840.16/2527

This study examines snow depth variability in Norway applying a number of statistical tools. A time series analysis of snow depth and length of snow season is carried out at eleven meteorological stations situated in three different parts of the country, named Region 1, Region 2, and Region 3. In addition, empirical orthogonal function (EOF) analysis and simple correlation analysis is performed in order to determine the spatial patterns and dominant modes of snow depth variability in Norway. The snow map service introduced by the Norwegian Meteorological Institute and Norwegian Water Resources and Energy Directorate in 2004 is evaluated at the same stations mentioned above. The focus is on the start and end of the snow season and the total number of snow days per hydrological year (Sep 1st – Aug 31st). A decreasing trend in snow depth is evident at nine of eleven stations. Stations in Region 1 and Region 2 reveal a later start of snow season, while stations in Region 3 reveal a slightly earlier start of snow season. An earlier end of snow season and a decrease in number of snow days is seen at all eleven stations. Region 3 shows the strongest decrease in the number of snow days and daily snow depth, probably due to low elevation and proximity to the coast, leaving this region more sensitive to global warming. Two leading eigenmodes (EOF1 and EOF2) accounting for 41.4% and 18.6% of the variability in snow depth, respectively, are identified and attempted defined. Existing Northern Hemisphere teleconnection indices are mainly established to explain variability in temperature and precipitation. Snow accumulation is dependent on both previous mentioned variables, and so the EOFs cannot be defined by one single teleconnection index. EOF1 appears to be related to East Atlantic/Western Russia (EA/WR) pattern, Arctic Oscillation (AO) and possibly to enhanced sea breeze, where the prevailing flow perpendicular to the southern coast of Norway helps push precipitation inland. The time series reveal a decadal variability ...