近50 a三江源地区蒸发量的变化特征及其影响因子分析

选用青海省三江源地区1964~2013年14个气象台站观测的基本气象数据,利用线性倾向性估计和Mann-Kendall检验方法等分析了三江源地区蒸发皿蒸发量的时空变化和变化趋势,并以完全相关分析方法进行蒸发量上升成因分析。结果表明:三江源地区年蒸发量总体呈显著上升趋势,其线性变化速率为30.1 mm/10 a,夏秋冬季蒸发量均呈显著上升变化,春季变化趋势不明显,夏季和秋季蒸发量上升对年蒸发量上升贡献最大;逐月蒸发量变化趋势均增加,但幅度各异;冬季蒸发量在2011年发生了突变,其余各季和年均未发生突变.蒸发量月际变化规律明显,表现为双峰型分布,双峰出现在5月和7月,最小值出现在1月;季节变化也十分明显,夏季蒸发量最大,其次为春季和秋季,冬季蒸发量最少,表明春夏两季蒸发量的多少对三江源地区水循环起重要作用。年和四季蒸发量呈现出西北部少,东南部及东北部多的分布特点,气候变化速率分布自西向东逐渐增大。蒸发量年际变化不剧烈,年蒸发量变异系数从西北向东南逐渐增大,四季蒸发量变异系数空间分布明显不同。年蒸发量与平均气温总体上呈正相关,与气温日较差、相对湿度呈负相关,平均气温上升、气温日较差和相对湿度下降是三江源地区蒸发量上升的主要因素。

STUDY ON CHANGING CHARACTERISTICS AND IMPACT FACTOR OF EVAPORATION OVER THREE-RIVER SOURCE AREA IN RECENT 50 YEARS

Based on the general meteorological data recorded by 14 stations from 1964 to 2013 in the Three-River Source Area, the spatial and temporal variation and trend of evaporation were analyzed using linear trend estimation and Mann-Kendall abrupt change test, and the causes of increasing evaporation were analyzed by the full correlation analysis. The results showed that the annual evaporation was increasing significantly in Three-River Source Area, and the linear change rate was 30.1 mm/10 a. The change of evaporation in summer, fall and winter was significant. The evaporation in summer and fall contributed to annual evaporation mainly. The monthly evaporation was generally increasing, but the rate different. The winter evaporation was changing abruptly in 2011. The other seasons and annual changing were not abrupt. The monthly evaporation was not significant, distributing double peaks, and peaks appeared in May and July, the minimum was in January. Seasonal change was obvious. The max evaporation was present in summer, secondly in spring and fall, minimum in winter. That showed evaporation in spring and summer played an important role on hydrologic cycle in Three-River Source Area. Annual and seasonal evaporation showed the northwest was less, the southeast and northeast was more. Climate change rate increased from west to east. The change of annual evaporation was not acute, the rates were increasing from northwest to southeast. The rates of seasonal evaporation distributed differently in space. Annual evaporation was positively correlated with average temperature, but had negative correlations with daily range of temperature and relative humidity. The main reasons of evaporation decline are the rise of average temperature, and the decline of daily range of temperature and relative humidity.