近31年来云南省潜在蒸散量变化成因

Causes of Potential Evapotranspiration Change in Yunnan During 1981-2011

为了探讨云南省潜在蒸散量(ET0)与气候变化间的效应,增强干旱发生预测的准确性,基于云南省1981—2011年52个站点气象数据,采用Penman-Monteith公式计算逐年四季潜在蒸散量(ET_(0,w)、ET_(0,s)、ET_(0,e)、ET_(0,u))以及年潜在蒸散量(ET_(0,y)),通过敏感系数和贡献率,分析了云南省ET_0变化的成因。结果表明(:1)云南省ET_0对气象因子的敏感程度从高到低为:平均气温>相对湿度>日照时数>风速;相对湿度为高敏感因子,但对ET0的影响低于平均气温和日照时数。(2)云南省ET_0变化的主导因子具有阶段性。1981—1990年,日照时数减少是ET_(0,y)下降的主要原因,1991—2011年,平均气温上升是ET_(0,y)上升的主要原因。(3)云南省ET_0变化的主导因子具有季节性。1981—1990年时段,云南省冬季ET_(0,w)上升的主导因子是平均气温,春、夏、秋季ET0呈下降的主导因子均为日照时数;1991—2011年时段,平均气温上升是冬季和秋季潜在蒸散量呈上升趋势的主要原因,春季ET_(0,s)下降和夏季ET_(0,e)呈上升趋势的主导因子均为日照时数。

The paper aims to explore the relationship between ET_0 and climate change in Yunnan forenhancing forecast accuracy of drought occurrence. Based on data of 52 meteorological stations in Yunnan from1981 to 2011, the causes for ET_0 change were analyzed by using sensitivity coefficient and the contributionrate, with the ET_0 estimated by Penman-Monteith equation, including the annual ET_0(ET_(0,y)) and the yearly ET_0 of four seasons(ET_(0,w), ET_(0,s), ET_(0,e), ET_(0,u)). The results showed that:(1) the order of sensitivity degree of ET_0 inYunnan to climatic factors was: the average temperature>relative humidity>sunshine hours>wind speed;though the relative humidity was a high sensitive factor, its impact on ET_0 was lower than average temperatureand sunshine hours;(2) the leading factor of ET_0 change in Yunnan had periodicity; the decreasing sunshinehours was the main factor leading to the decrease of ET_(0,y) in 1981-1990, and in 1991-2011 the rising ofaverage temperature was the leading factor of the ET_(0,y) increase;(3) the leading factor of ET_0 change in Yunnanhad the seasonal characteristics; in 1981-1990, the leading factor of the increase of ET_(0,w) in winter was theaverage temperature, and the leading factor of the other three seasons was the sunshine hours which led to their ET_0decrease; in 1991-2011, the rising of average temperature was the dominating factor leading to theincrease of ET_(0,w) and ET_(0,u), and the leading factor of both the decrease of ET_(0,s) and the increase of ET_(0,e) wassunshine hours.