基于MOD16A2的毛乌素沙地实际蒸散量时空稳定性模拟

基于MOD16A2遥感数据产品,统计分析毛乌素沙地2000—2014年地表实际蒸散量(ET)多年年、月平均值,探讨不同时空尺度下ET的分布特征及变化趋势。结果表明:毛乌素沙地ET年际月均的时空分布规律总体呈现显著地带性和季节性。冬春季节,ET呈下降趋势,下降速率53.24%;夏秋季节,ET先增后减。沙地4月份ET最低最干旱,多年ET均值在10 mm以下,9月和12月出现2次峰值,其ET量约为20 mm和25 mm。多年ET年均值呈现东南部高于西北部的趋势。主要蒸散范围在17.5～22.5 mm之间。15 a间毛乌素沙地波动区间面积排序为:轻度(33.67%)>中度(32.04%)>强烈(18.46%)>微弱(15.83%)。ET总体表现为西南波动强烈,东北波动较缓,中部平稳。15 a间,毛乌素沙地ET增加趋势占34.38%,减少和不变趋势基本一致,各占28.49%和28.13%。沙地总体增加大于减少,说明沙地气候改善,干旱减轻。MOD16产品反演结果与多年气象、文献等研究结果一致,能够满足毛乌素沙地地表蒸散量时空变化分析的要求。

Simulation on spatio|temporal stability of ET based on MOD16A2 in Mu Us sandy land

This paper used MOD16A2 remote sensing data to analyze the mean value of evapotranspiration (ET) at different years and months of 2000-2014 in the Mu Us sandy land, in order to discuss the distribution characteristics and variation tendency of ET in different time|space scales. The results showed that, the temporal distribution of ET in the Mu Us sandy land had significant zonality and seasonality variation characteristics. ET had a decreasing trend in winter and spring, which was dropping by the rate of 53.24% at first, on the contrary, ET increased first and then decreased in the summer and autumn. The lowest mean value of ET in April was less than 10 mm and the others peaks appeared in September and December that mean values were 20 mm and 25 mm. The annual average of ET in the southeast was higher than that in the northwest, which changed from 17.5 to 22.5 mm. For the past 15 years, the order of fluctuating area was: mild (33.67%) > morderate (32.04%) > severe (18.46%) > slight (15.83%). ET fluctuated strongly in the southwest, then slowly in the northeast and steadily in the middle of Mu Us sandy land. During the past 15 years, the ET increased by 34.38%, decreased by 28.49%, and remained unchanged by 28.13%. Mu Us sandy land showed that the increasing trend was rapider than the decreasing trend. Meanwhile, it indicated that the climate of this area improved and the drought was reduced. The results illustrated that MOD16A2 product was applicable for the analysis of Mu Us sandy land distribution characteristic of ET, which were satisfied the requirement of spatial and temporal variation analysis.