1961—2010年松花江流域实际蒸散发时空变化及影响要素分析

Changes of Actual Evapotranspiration over the Songhua River Basin from 1961 to 2010

采用1961—2010年松花江流域60个气象站逐日资料,基于平流-干旱模型(AA模型)计算并分析了流域实际蒸散发时空变化特征,采用相关分析方法研究了影响实际蒸散发变化的主要气象要素。结果表明,1961—2010年,松花江流域年均实际蒸散发为420.8 mn,总体呈现增加趋势,增加速率为4.9 mm/10a,呈"减-增-减-增"年代际波动变化。季节上,春、冬两季实际蒸散发增加趋势较明显,夏、秋两季则呈现与年实际蒸散发类似的年代际波动。春、夏、秋三季和年实际蒸散发的空间分布特征基本一致,高值主要出现在流域南部,低值区主要分布在流域西部。冬季绝大部分区域的实际蒸散发呈现微弱上升趋势。1961-2010年,松花江流域年和四季的平均气温、最高气温和最低气温都呈上升趋势,其中平均气温和最低气温上升显著,日照时数和风速大都呈现显著下降趋势。相关分析结果表明,松花江流域实际蒸散发的时空变化是各气象要素共同影响的结果,而且各气象要素在不同时期对实际蒸散发的影响是有差异的。总体上看,松花江流域实际蒸散发的增加主要是由平均气温,特别是最低气温的增加引起,特别在春、冬季体现得较为明显。夏、秋季节,影响实际蒸散发的要素包括气温日较差、实际水汽压、平均风速及降水量等气象要素,但夏、秋季节这些要素的多年变化趋势不明显,导致夏、秋实际蒸散发的总体变化趋势并不明显。

Based on the daily data from 60 meteorological stations for the period of 1961-2010,spatial and temporal trends of actual evapotranspiration （E） were analyzed by applying the Advection-Aridity model in the Songhua River basin.The research results show that annual E in the Songhua River basin shows a significant upward trend at a rate of about 4.9 mm per decade.More significant upward trend can be detected in spring and winter.While the summer and autumn E show obvious inter-decadal fluctuation.Annual E has similar spatial distribution pattern to those of spring,summer and autumn,with high values located in the southern part and relatively low values in the west part.In 1961-2010,the annual and seasonal air temperatures,especially the minimum air temperature of the Songhua River basin,have significant upward trends,but the sunshine duration and wind speed have significant downward trends.Correlation analysis results show that,the spatial-temporal distribution of the E is derived from the comprehensive impact of the main meteorological factors.In general,the increase of the average/minimum air temperature can give explanations for the rising of annual and seasonal E,especially in spring and winter.In summer and autumn,the E has no significant trend in 1961-2010,because the main meteorological factors such as daily temperature range,actual vapor pressure,wind speed and precipitation all have no obvious trend.