基于MOD16产品的我国2001-2010年蒸散发时空格局变化分析

蒸散发的时空格局分析对理解气候变化与水资源之间的相互影响具有重要的作用。本文基于MODIS全球蒸散发产品（MOD16），分析了2001-2010年我国陆面蒸散发的时空格局变化，得出以下结论：（1）站点尺度和流域尺度的精度验证结果表明，MOD16产品对于我国森林、农田生态系统类型，以及辽河、海河、黄河和淮河流域的模拟精度较高；（2）2001-2010年，我国年均蒸散发为532±10 mm，年内蒸散值变化最大的是东北区，月均蒸散变异系数为0.87，而西北区变化幅度最小，变异系数为0.19；（3）2001-2010年，我国陆面蒸散发年际变化总的趋势不明显，占陆地面积11.2%区域的蒸散发呈显著减少趋势（p＜0.05），主要分布在青藏高原中部，内蒙古中东部地区及新疆北部，只有2.3%的区域的蒸散发增加趋势显著，（p＜0.05），主要分布在黄土高原地区、黄淮海平原及东北平原；（4）通过对比干旱指数变化趋势、植被指数变化趋势图可以看出，蒸散发显著减少的区域主要分布于干旱加剧的半干旱地区，而蒸散发显著增加的区域主要位于植被变好的地区。

Spatial-temporal Variation of Terrestrial Evapotranspiration in China from 2001 to 2010 Using MOD16 Products

Terrestrial evapotranspiration （ET） is a key process in the climate system and a nexus of the water and energy cycles. Understanding the temporal and spatial change of ET is important to analyze the climate impact on water resource. However, large scale ET estimation methods are still in evolution due to the complexity of processing ET. With the aid of MODIS ET products （MOD16）, we obtained the 10-year spatial-temporal data sets of terrestrial ET in China from 2001 to 2010.MOD16 ET products were first validated at 8 flux towers and 10 large basins in China. The results show that although some uncertainties are present, the magnitudes and spa-tial pattern of ET in China are basically reasonable. The MOD16 products withthe best performances were ob-served at sites with forest and crop land cover, as well as in four basins in the north of China.The average annual terrestrial ET in China from 2001 to 2010 is 532 ± 10 mm.The seasonal change of the ET in Northeast China is most obvious with a coefficient of variation （CV） of 0.87 based onthe average monthly ET, while the Northwest China has little seasonal variations making the CV is only 0.19. Generally, the estimated terrestrial ET in China＆amp;nbsp;shows littlesignificant variation during the 2001 to 2010 period. On the regional scale, approximately11.2% of the areas show significant negative ET trends, which occur mainly in the center of Tibetan Plateau, northeast of Inner Mongolia and the north of Xinjiang. Only 2.3% of the areas show significant positive ET trends, which mostly occur in Loess Plateau, Northeast Plain and Huang-Huai-Hai Plain. According to the analysis of the maps of the linear trends of PDSI and NDVI in China during 2001 to 2010, we can see the negative ET mainly occurs in the semi-arid areas which under go increasing drought;while the positive ET occurs in areas where the vegeta-tion is turning better after large-scale ecological restoration projects were implemented.