1961—2007年云南干季干湿气候变化研究

Dry-Wet Climate Change of the Dry Season in Yunnan During 1961-2007

从影响自然干湿变化的多种因素出发,基于云南省15个站点1961—2007年干季9项气候要素实测数据,应用因子分析法研究云南干季干湿气候变化特征。提取了表征干季干湿气候变化的3个公共因子,阐明了云南干季干湿气候变化特点和原因。结果显示:1960年代以来5个年代干湿气候变化明显,变化原因各异,总变化趋势是湿度缓降、干旱强度渐强;1960—1980年代都处于中等干旱偏弱态势,进入1990年代后降水时间分布不均和气候变暖导致干季气候持续典型偏干;干季总降水量变化趋势有不确定性,年代际变化明显、变率不大,但其年际变化突出造成干季干湿状况年际波动大。

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.