中文摘要：

地表温度是生态系统中极其重要的环境因子,中小尺度区域的热量资源和热场分布对绿洲冷岛效应的研究以及评价绿洲的稳定性具有重要意义。利用LandsatTM卫星影像,采用单窗算法,反演了张掖绿洲1999年和2007年两个时期的陆地表面温度（LST）,构建了绿洲＂冷岛＂比例指数,定量分析了张掖地区近8年来绿洲冷岛效应的时序变化,并且通过对张掖热场的分析,揭示了冷岛效应的空间变化特点。结果表明：①张掖绿洲冷岛效应明显,但近8年来有减弱的趋势;②南北向绿洲内部和荒漠内部温度差异均在减小,城区温差在扩大;东西向绿洲内部和城区内部温度差异均在减小,荒漠温差在扩大;③水体、耕地、草地、建设用地和林地的平均LST有所降低,荒漠等未利用土地LST有所升高,其中建筑用地的LST减幅最大。为研究绿洲的光、热、水、土的空间分布及区域变化,评价绿洲的稳定性提供了一种新的角度,同时对绿洲与荒漠之间的大气物理模型及动力学有一定参考意义。

英文摘要：

As a product of the regional differences in arid zone internal,oasis is a complex dissipative structural system.Unique climatic characteristics and surface properties difference between Gobi and oasis underlies the formation of the non-uniform heat in arid zone.Relative to the surrounding desert,oasis environment is a cold source,then,the most significant effect of Oasis,＂Cool island＂ effect,is formed.＂Cool island＂ effect is a major aspect in oasis effect.The land surface temperature （LST） is a very important factor in ecosystem.The resource and distribution of thermal energy have significance to the analysis of the cold island effect and evaluation of the oasis ecological environment condition in middle and small scale areas.Zhangye oasis lies in the middle reach of Heihe River.LST of Zhangye oasis was retrieved from Landsat TM images in 1999 and 2007 by using Mono-window Algorithm.LST map was divided into 7 grades.In this paper,a Oasis-Cold-Island Ratio Index was constructed,and the west to east and the north to south temperature profiles was also established taking the Ganzhou county as the centre.The spatial-temporal change of ＂cold island＂ effect in Zhangye oasis for resent 8 years has quantitatively analyzed.Through the analysis to Zhangye oasis temperature field,the representation aspects of the spatial variation of ＂the cool island＂ effect were summarized.Results indicate that,from 1999 to 2007,high temperature area expanded rapidly,which was equivalent to 4.83 times that of 1999.Extremely high temperature area also increased.LSP of alluvial plains in the west of Zhangye oasis showed a slight decline generally,while land surface temperature of all desert and Gobi in the east of Zhangye oasis rose sharply during the past 8 years.In 1999 and 2007,the Oasis-Cold-Island Ratio Index was 0.028 1 and 0.008 2,respectively.Significant reduce of the Oasis-Cold-Island Ratio Index reflected that the ＂Cool island＂ effect was weakening.The interior temperature gradient of oasis and city areas ch