Abstract: From the angle of manifold factors affecting natural dry-wet change, the research was performed in order to further understand and deal with climate change scientifically. Based on 1961-2007 observed data of nine climatic elements from 15 stations, the factor analysis was used to investigate the dry-wet climate change in the dry season in Yunnan. Three common factors were extracted from the nine climate variables to describe the dry-wet climate change for the dry season; and the features and causes of the change were clarified. The results show that the dry-wet climate has evidently changed since the early 1960s because of the influences of different factors in different decades. The general trends of dry-wet climate change were described as slow decrease in humidity and gradual enhancement in drought intensity. The climates were in a state of the drought of a weaker medium strength during the 1960s-1980s; but since the early 1990s, the markedly drier climate has continually occurred in the dry season owing to the misproportionally temporal distribution of rainfall and the climate warming. The variation tendency of the total precipitation for the dry season had uncertainty regardless of its obvious interdecadal changes of relatively small variance ratio; and its prominent interannual change led to the big interannual fluctuations for dry-wet climate.

Key words: climate change, dry-wet climate, factor analysis, dry season, Yunnan