Abstract : 3K.5
A statistical study of the relationship between the North Atlantic oscillation and Swiss Alpine snow depth

Stephen Mobbs, William Billany
University of Leeds

An analysis of snow depth observations covering the period from 1931 to 1999 in the Swiss Alps has been made. The study has revealed a significant relationship between the North Atlantic Oscillation (NAO) and snow depth in the Swiss Alps. On an interannual timescale the relationship is largely masked by other processes. The relationship was found to be most strongly pronounced on an eight year timescale, with periods of a negative phase in the NAO, associated with larger seasonal snow depths. A one season time-lag in the relationship was found, which could not be explained. The influence of the NAO on snow depth observations weakens to the south and east of the Swiss Alps, with an overall mean correlation of -0.60. The strongest correlating regions are situated in the west and north of the Swiss Alps with a mean correlation of -0.74. This may be explained by the stronger Atlantic influence towards the west of the region. Correlation values were not found to vary significantly with altitude. This provides evidence in support of the hypothesis that precipitation and not temperature is the main variable that is governed by the NAO.