基于MODIS卫星资料研究三峡工程对库区地表温度的影响

Impacts of Three Gorges Project on Land Surface Temperature Based on MODIS Dataset

利用2001—2012年MODIS地表温度资料,分析了三峡库区蓄水后水体对冬、夏两季白天和夜间地表温度的影响。由于下垫面水陆和地势的影响,白天地表温度高值区主要位于四川盆地东部,夜间则主要出现在长江江面;温度日较差在长江和海拔较高地区较小,且夏季水体日较差小于冬季。分别用水体和I^X缓冲区地表温度减去XI缓冲区去除气候背景场影响,发现冬季白天地表温度趋势在水体及I^VI缓冲区由下降转为上升,夜间地表温度在相同距离内显著升高。利用蓄水后(2003—2012年)地表温度和日较差分别减去蓄水前(2001—2002年)剔除地形影响,发现:冬季,三峡工程水库蓄水对局地地表温度具有增温效果,且强度和范围夜间大于白天;夏季,对地表温度有降温作用,白天大于夜间;同时,冬、夏季的温度日较差减小;且水体对局地地表温度和日较差的影响随距水体距离的增加而减小,其影响范围基本维持在0~8 km范围内。

Using MODIS dataset during 2001-2012, impacts of water body at daytime and nighttime on land surface temperatures due to the Three Gorges Project were analyzed both in winter and summer. To fully consider the impacts of topography, it is found that high land surface temperature mainly located in the eastern part of Sichuan basin at daytime, and in the Yangtze River at nighttime. Diurnal temperature ranges in the Yangtze River and high altitude area are small, also diurnal temperature ranges in the water body in summer are less than those in winter. After removing impacts of climate background by subtracting the average land surface temperatures over the buffer zone XI from the water body and buffer zones I-X, temporal trends in winter daytime climb up in water body and buffer zones I-VI, land surface temperatures at winter night in the same range also have significant rise. Removing the impacts of climate background and then separating the topographical effects through subtracting the variables after impounding （2003-2012） from ones before impounding （2001-2002）, it is shown that, relative to the period before impounding, winter land surface temperatures after impounding obviously increase, and the intensity and range at nighttime are stronger than at daytime. Summer land surface temperatures decrease, the intensity at nighttime is weaker than at daytime, respectively, and the corresponding diurnal temperature ranges in both winter and summer decrease. With increment in distance from the water body, additionally, the climatic effects of reservoir become weaker. The potential spatial zones of influences induced by the Three Gorges Project are limited to the distances of 0-8 km from the water body.