Abstract : O.3
A quantified correlation between Swiss Alpine snow cover duration and atmospheric thickness for a range of terrestrial altitudes and snow depths

Victoria Smith, Stephen Mobbs
Institute for Atmospheric Science

Regional Climate Model predictions for the Swiss Alps have forecast a localised warming by 2100 of 4°C. Anomalously warm winters during the past 40 years ave evoked speculation concerning potential consequences for the skiing industry, exposing the vulnerability of low altitude resorts to suffer significant decreases in snow cover duration. In order to maintain viability, resorts require a snow depth of 30cm for a duration that includes both the Christmas and Easter holiday periods, typically 130 days.

Mean atmospheric 1000-500 hPa thickness has been calculated using ECMWF ERA-40 re-analysis pressure data for the winter seasons from 1960 to 1999. This has been compared to snow cover duration, during these seasons, at 27 locations within the Southern Swiss Alps whose altitudes range from 910m to 1800m. Duration was calculated for three snow depth thresholds as the number of consecutive days with 5cm, 30cm, and 50cm of snow. Strong correlation were found to exist between all locations and depth Similarly, strong correlations were found to exist between mean 500 hPa height and snow duration for all locations and depth thresholds. However, the highest and most significant correlations were found at the lower altitudes.