Glacier Variation and Weather

Statistical results of measurements of glacier variations in Switzerland 1891–1965 are compared with deviations from average temperature and precipitation in summer for stations above 2000 m. The result is interpreted in terms of meso-scale glacier–weather relations. A correlation between glacier mass budget and deviation from the average height of the 500 mbar surface indicates the importance of cyclonic and anticyclonic conditions during the ablation period, and therefore of the frequency of certain Grosswetterlagen which has been studied for the period 1881–1965. The pattern of the difference of Grosswetterlagen favourable and unfavourable for glaciers resembles the pattern of glacier variations and also of mass-budget data. Atmospheric circulation in zonal and meridional forms, as expressed by the frequency of Grosswetterlagen has to be considered by seasons. There is no simple relation between the intensity of zonal circulation and glacier variation. Glacier recession of the last few decades seems to be caused by the fact that meso-scale weather conditions mainly in the ablation season have become much less cyclonic than in the decades 1886–95 and 1906–15.