REGIONAL BEHAVIOR OF MINIMUM TEMPERATURES IN SWITZERLAND FOR THE PERIOD 1979-1993

A series of anomalously cold and warm winters which occurred in Switze rland during the 15-year period from 1979 to 1993 has been analyzed in detail in terms of temperature minima. The warm winters between 1988- 1992 were particularly marked in the Alps, where lack of snow had seve re consequences for the tourist-based economies of mountain communitie s. The investigations presented here focus primarily on minimum temper ature records for up to 88 climatological observing sites distributed over Switzerland. Analyses of the departures of temperature minima fro m the 15-year means in warm and cold winters has shown that there is a very significant altitudinal dependency of the anomalies except at lo w elevations which are subject to fog or stratus conditions; the strat us tends to decouple the underlying stations from processes occurring at higher altitudes. It is also shown that there is a switch in the gr adient of the temperature anomaly with height from cold to warm winter s. For warm winters, the higher the elevation, the stronger the positi ve anomaly; the reverse is true for cold winters. The statistics for t he 88 observational stations provide a measure of the damping of the c limate signal as an inverse function of height. The altitudinal depend ency of temperature departures from the mean are the most important fe ature, followed by latitudinal effects (north and south of the Alps); continentality is not seen to be a major factor in determining the geo graphical distribution of temperature anomalies at this scale. The pre sent investigation also emphasizes the fact that high elevation record s can more readily identify significant interannual climatic fluctuati ons than at lower-elevation sites. This is also likely to be the case for longer-term climate change, where possible greenhouse-gas warming would presumably be detected with more clarity at higher elevations. T his type of study can help orientate future high-resolution climate mo del studies of climate change and in particular the assessment of mode l capability in reproducing a range of possible temperature anomalies and their altitudinal dependency.