商丘近44年蒸发量变化及其影响因子分析

Evaporation Variation and Its Relationship with Meteorological Factors in Shangqiu from 1961 to 2004

利用商丘市8个台站1961-2004年的20cm口径蒸发皿资料,进行蒸发量的年际变化、年代际变化、季节变化以及月分布的分析,结果显示蒸发量存在显著的减少趋势。年际间减少趋势通过了99%的置信度水平,各季节蒸发量以春季和夏季减少最为明显。同时还分析了近44年来日照、风速和温度的变化趋势,并计算了这些气象因子与蒸发量变化的相关系数。分析表明日照时数减少和风速减小是造成商丘市蒸发量下降的主要因素,而气温上升对蒸发量的影响不十分明显。

The interdecadal, interannual and seasonal evaporation variations are analyzed on the basis of the available observation data from 1961 to 2004 from eight stations over Shangqiu. The results show that although the annual mean air temperature showed an increasing trend over the past 44 years, the evaporation of the same time showed a remarkable decreasing trend, which passed the statistical test with a significant level of 99%. The evaporation variation is most obvious in spring, and least in winter. Compared with the 1960s and the 1970s, the annual pan evaporation rate in the 1980s and the 1990s decreased by about 34 mm. The cause is directly correlated to the decreased average wind speed and sunshine.