An analysis of regional climate-change in Switzerland
Martin Beniston, Martine Rebetez, F Giorgi & M Marinucci
| Résumé |
An analysis of daily climatological data covering the period from
1901 to 1992 for four locations in Switzerland (Zurich, Lugano,
Davos, and Santis) has been made. The study has highlighted the
fact that climate change this century is characterized by increases
in minimum temperatures of about 2K, a more modest increase in
maximum temperatures (in some instances a decrease of maxima in the
latter part of the record), little trend in the precipitation data,
and a general decrease of sunshine duration through to the mid
1980s. The interannual variability is generally large, and
filtering of the data to remove high-frequency noise shows that the
regional climate undergoes a series of fluctuations of between 8 and
20 years' duration. The temperature change over this century is of
greater magnitude than the global temperature changes published in
the literature, reflecting an amplification of the global signal in
the Alpine region; warming has been most intense in the 1940s,
followed by the 1980s; the cooling which intervened from the 1950s
to the late 1970s was not sufficient to offset the warming in the
middle of the century. Pressure statistics have been compiled as a
means of providing a link between the regional-scale climatological
variables and the synoptic, supra-regional scale. These statistics
show that pressure also exhibits a number of decadal-scale
fluctuations, with the appearance of a new and anomalous behavior
in the 1980s; in this decade, pressure reaches annual average
values far higher than at other times this century. The pressure
field is well correlated with the North Atlantic Oscillation (NAO)
Index for distinct periods of the record (1931-1950 and 1971-1990)
and is almost decorrelated from the NAO Index for the other decades
of the century; this is indicative of transition from one climatic
regime to another, dominated by zonal flow when the correlation
with the NAO Index is high. In the 1980s, when zonal flow over the
North Atlantic is strong, episodes of persistent, anomalously high
pressures (blocking highs) are seen to occur over Switzerland,
particularly during the winter season. The difference between the
zonal and non-zonal regimes is particularly marked between the
decade of the 1950s and that of the 1980s. The impact of this
change between the 1950s and the 1980s on a number of
climatological variables has been investigated statistically in
order to provide an illustration of the manner in which changes in
synoptic regimes (i.e., 'climate change') impacts upon climate
characteristics on a regional scale. The analysis shows that
temperature, precipitation, snow depth, and sunshine duration are
indeed sensitive to large-scale influences; not only can yearly
mean changes be quantified, but also seasonal and monthly
fluctuations. |
| Mots-clés |
NORTHERN-HEMISPHERE, TEMPERATURE, VARIABILITY |
| Citation | Beniston, M., Rebetez, M., Giorgi, F., & Marinucci, M. (1994). An analysis of regional climate-change in Switzerland. Theoretical and Applied Climatology, 49(3), 135-159. |
| Type | Article de périodique (Français) |
| Date de publication | 1994 |
| Nom du périodique | Theoretical and Applied Climatology |
| Volume | 49 |
| Numéro | 3 |
| Pages | 135-159 |