干旱区典型绿洲热场分布规律研究——以渭干河—库车河三角洲绿洲为例

Thermal field distributions of typical oasis in arid region:A case study in Weigan and Kuqa rivers delta oasis

利用Landsat 7 ETM+遥感资料热红外波段定量反演晴空状态下夏季干旱区典型绿洲地表真实温度,运用影像叠加分析、直方图比对、缓冲区分析和空间自相关分析及剖面线分析等方法,分析其热场分布规律。结果表明:绿洲热场分布具有显著正空间自相关特性,Moran′s值为0.5489,z值为48.44,同时呈现出显著的局部空间集聚现象;就局部而言,在相同热力环境下,由于盐碱地与裸地热容量不同,盐碱地温度低于周边裸地温度,盐碱地平均温度比周边300、900 m和1500 m缓冲区裸地的平均气温分别低0.59、0.44℃和0.26℃;然而盐碱地大多分布在裸地的高温区中心,且温度变化幅度小,在裸地低温区周围分布较少,所以就整体而言,裸地平均气温低于盐碱地温度,热场分布规律依次为水体温度21.65、耕地温度27.86、林草地温度35.59、城镇温度40.06℃、裸地温度42.07℃。水体、城镇、盐碱地、裸地的温度波动较小,热力景观单一,热场分布均匀,而耕地和林草地的温度梯度大,热力景观复杂多样,热场分布极不均匀,局部热场存在突变现象。绿洲荒漠交错带的面积较大,可以降低荒漠对绿洲的热力侵蚀,对保护绿洲有重要作用。

Based on Landsat 7 ETM plus remote sensing data, the real land surface temperature of the typical oasis was retrieved under the clear weather of summer in arid region using a thermal infrared band of satellite image. The thermal field distributions were analyzed by using a satellite image overlaying analysis, a histogram comparison, a buffer analysis, a spatial autocorrelation analysis and profile-line analysis methods, etc.. The results indicate that the thermal field distributions of oasis are of significantly positive spatial autocorrelation. Moran＇s value is 0. 5489 and Z value is 48.44. At the same time,it takes on the notably local spatial cluster phenomenon. For the local study area, temperature is lower in saline-alkali soil than in the surrounding bare land under the same thermal environ- mental condition because of their different specific heat capacity. Mean temperature is lower 0. 59℃ ,0. 44℃ and 0. 26℃ in saline-alkali soil than in the surrounding buffer bare land of 300 m,900 m and 1500 m,respectively. However, the saline-alkali soil is often located in the center of high temperature region of bare land and seldom in the low temperature region, and the amplitude of temperature variation is not large. Consequently, the mean temper- ature is lower in bare land than in saline-alkali soil as a whole,and it is 21.65 ℃ in water bodies ,27.86℃ in cultivated land,35.59 ℃ in woodland and grassland,36. 52 ~C in town,40. 06 ℃in bare land and 42. 07 ℃ in salinealkali soil. Temperature variation is not large in water bodies, town, saline-alkali soil and bare land, and their ther- mal landscapes are simple and thermal filed distributions are even. Whereas the temperature variation is large in cultivated land and in woodland and grassland, and their thermal landscapes are complex and thermal filed distributions are uneven. There are abrupt changes in the local thermal fields. The areas of ecotone between oasis and desert are large, which could reduce the thermal erosion of desert to oasis and protect the oasis.