中国北方近45年蒸发变化的特征及与环境的关系

Characteristics of the Changes in Pan Evaporation over Northern China during the Past 45 Years and the Relations to Environment Factors

对整个中国北方及东北、华北、西北区东部和西北区西部四个子区域蒸发皿蒸发时间序列的分析发现,近45年(1960—2004年)中国北方蒸发皿蒸发的下降趋势明显,并且在空间上从东北向西北的下降趋势逐渐增大。同时结合降水、相对湿度、日较差及日照等环境因子对过去45年的变化特征及与蒸发皿蒸发之间的关系进行了分析,结果表明:在中国北方,无论是在半湿润的东北区还是干旱的西北区,气温日较差和风速都是影响蒸发皿蒸发的最重要的因子,这可能是导致蒸发皿蒸发下降的主要原因;而降水、相对湿度、日照等的作用也不可忽视。

Analyzing the time series of the whole Northern China and the sub-regions of it, Northeastern China, northern China, the east part and the west one of Northwestern China, it is found that the pan evaporation obviously decrease in the past 45 years（1961-2004）. And the space pattern of change is： Pan evaporation declined least in the Northeast China, when moving westward, its decrease trend gradually increase. Analysis of the relations among pan evaporation and some environment factors, for instance, wind speed, precipitation, relative humidity and diurnal temperature range, etc, show that either whole North China or in its sub-regions both the diurnal temperature range and wind speed were the most important factors, while precipitation, relative humidity and temperature, etc, were also important impact factors on pan evaporation. In total, many meteorology factors have a close correlation with pan evaporation. The correlation changes with the change of time and space in the past 45 years, the influences of the diurnal temperature range and wind speed changes on pan evaporation change were dominant, they are the primary reasons for the decreasing of pan evaporation in the Northern China in the past 45 years.