珠江流域蒸发皿蒸发量的变化特征及其原因分析

Variation characteristics and impact factors of pan evaporation in Pearl River Basin,China

为探讨珠江流域蒸发皿蒸发量的时空变化特征,该文利用1960-2001年65个气象站的小型蒸发皿观测资料,采用Mann-Kendall趋势检验方法、完全相关系数法以及GIS空间分析技术分析了蒸发皿蒸发量的变化趋势及其可能原因。结果表明:近42a来整个珠江流域年蒸发皿蒸发量呈显著的减少趋势,减少速率为2.79mm/a。四季中,夏季(6-8月)与秋季(9-11月)蒸发皿蒸发量变化趋势不显著,冬季(12月-次年2月)和春季(3-5月)均呈现明显下降趋势,其中春季下降最为显著;就各月份而言,除6、11、12月3个月份呈不显著增加趋势外,其余9个月份均呈不同程度的下降趋势。蒸发皿蒸发量的变化趋势存在区域差异性,全流域仅有少数区域显示为增加趋势,其他大部分地区均以显著减少为主,减少速率最大的区域集中在西江中游、北江与东江下游。珠江流域蒸发皿蒸发量的减少主要是由热力因子日照时数、气温日较差和动力因子平均风速的减少引起的,该结果可以为流域气候变化及水文循环研究提供参考。

With the data of monthly 20 cm pan evaporation and its impact climatic factors at 65 meteorological stations in Pearl River Basin from 1960 to 2001,spatial-temporal change characteristics of pan evaporation are analyzed by using Mann-Kendall test method,complete correlation methods and geographic information systems. The results showed that there was a significant decreasing trend in the observations on pan evaporation in Pearl River Basin,with an average rate of 2.79 mm/a in the whole basin. In autumn and summer,pan evaporation had no apparent decline trend;but in spring and winter,there existed a significant decreasing trend. The spatial distribution of the change rate showed that the maximum decrease of annual pan evaporation mainly occurs in the south and middle of Pearl River Basin. On the attribution,the paper calculated the complete correlation coefficients of eight climate factors with pan evaporation. And decreases in the sunshine duration,diurnal temperature range and the average wind speed were found to be the main influencing factors leading to the decrease of pan evaporation. These can provide references for study of climate change and hydrologic cycle in Pearl River Basin.