Lokale Windsysteme in der Charazani-Talung (Bolivien)

Abstract

Local wind phenomena constitute an important ecological factor in the tropical Andes. In this paper the particular case of the upper Charazani Valley is discussed on the basis of anemographic data taken between July 1981and June 1984. The slope winds exhibit definite seasonal variations, and the upslope component is dominating throughout. It is shown that the circulation of slope winds, which depends on the orographical setting, has a decisive influence on the hygric differentiation of the valley. Moreover, the valley wind dominates over the less stable mountain wind throughout the whole year. Nevertheless, this is a typical example of a valley-mountain wind system, with both wind directions occurring regularly. Using cluster analysis, it can be distinguished between five different types of wind days. According to their frequency the individual months have been classified into three wind seasons. It is shown that the predominance of the valley wind and its seasonal variation can be related to the over-heating of the mountains and to the high reaching summer anti cyclone above the Altiplano. Thus the local wind system can be understood as a part of a larger mountain circulation, which to a large extent determines the macroscale climate.