近50年来四川省潜在蒸散量变化成因研究

Attribution Analyses of Potential Evapotranspiration Change in Sichuan in Recent 50 Years

利用FAO-56Penman-Monteith法计算四川省4个分区1960—2010年逐月的潜在蒸散量(ET0),采用贡献率法分析ET0近50a来变化成因。结果表明:整个四川省、四川盆地和盆周山地日照时数和风速下降对ET0的负贡献超过平均、最高和最低气温上升以及相对湿度下降对ET0的正贡献,使ET0呈下降趋势;川西北高原平均、最高和最低气温上升以及相对湿度下降对ET0的正贡献超过风速和日照时数下降对ET0的负贡献,使ET0呈上升趋势;川西南山地平均、最低气温、日照时数和风速的下降对ET0的负贡献超过了最高气温上升和相对湿度下降对ET0的正贡献,使ET0呈下降趋势。四川省和四川盆地日照时数下降是ET0下降的主要原因,盆周山地和川西南山地风速下降是ET0下降的主要原因,川西北高原最低温度上升是ET0上升的主要原因。

FAO-56Penman-Monteith method was used to estimate the monthly potential evapotranspiration(ET0)from 1960 to 2010in four different regions of Sichuan Province.Then the causes for ET0 change in recent 50 years were analyzed by contribution rate method.Results show that in the whole province,Sichuan basin and mountainous area around basin,the negative contribution of decreased sunshine duration and wind speed to ET0 is greater than the positive contribution of increased average,maximum,minimum temperature and decreased relative humidity to ET0,which causes ET0 to decrease.While in northwest Sichuan plateau the positive contribution of upward average,maximum,minimum temperature and downward relative humidity to ET0 exceeds the negative contribution of downward sunshine duration and wind speed,inducing ET0 to increase.In mountainous area of southwest Sichuan the negative contribution of decreased average,minimum temperature,sunshine duration and wind speed to ET0 exceeds the positive contribution of increased maximum temperature and decreased relative humidity,resulting in decline of ET0.The decreased sunshine duration in the whole province and Sichuan basin and the decreased wind speed in mountainous area around basin and mountainous area of southwest Sichuan are the primary contributors to ET0 decrease,respectively.The increased ET0 in northwest Sichuan plateau is mainly attributed to the increased minimum temperature.