呼伦湖水面蒸发量计算及变化特征分析

Caculation and characteristics of Hulun lake surface evaporation

针对呼伦湖区小型蒸发器水面蒸发量折算系数难以确定及观测资料系统性较差的问题,选择penman公式及其简化式计算水面蒸发量,并对结果进行比较验证。两种方法的精度均较高,且简化式计算量小,不易出错。经过统计相关分析,将新巴尔虎右旗、新巴尔虎左旗、满洲里的计算蒸发量的平均值作为呼伦湖水面蒸发量。在此基础上,通过敏感性分析,确定水面蒸发的主控因子。结果表明:不同时间、地点,气象因子的敏感性不同,但相同的是,5、10月风速决定蒸发的大小,9月则为相对湿度,其他月份为最高温度和日照时数。借助累积距平值分析1960～2008年湖面蒸发量及各气象因子年均值的变化,发现1982年后湖面蒸发的降低的原因是气候条件发生了变化,即温度、日照时数、风速降低,相对湿度增加。

For the problem of undefined conversion coefficient of small evaporation pan in Hulun lake catchment and short of measured data,the classical and simplified Penman formulas were used to calculate the water evaporation.The accuracy of both methods is high,while simplified version has a small calculated amount and is less error-prone.The average water surface evaporations of New Barag Right Banner,New Barag Left Banner and Manzhouli was regarded as that of Hulun lake after correlation ship analysis between calculated and measured value.Sensitivity analysis was done on the basis of regression equation,which was derived from stepwise regression between simulated evaporation and meteorological factors.The results showed that the sensitivity of meteorological factors in different time and places were different,nevertheless,there was something in common,that was,wind velocity was the most sensitive factor in May and October,while in September it turned out to be the relative humidity,in other monthes the maximum temperature and sunshine hours were the sensitive factors.After analyzing the change of lake surface evaporation and meteorological factors and theirs cumulative sum from 1960 to 2008,it came to the conclusion that the reduction of evaporation after 1982 was caused by the change of climatic conditions,i.e.temperature,sunshine hours and wind velocity were decreasing,while the relative humidity was increasing.