基于MODIS数据的石羊河流域地表温度空间格局

利用2010年4期MODIS影像, 基于植被指数、 地表比辐射率、 大气透过率和星上亮度温度, 采用分裂窗口算法, 反演石羊河流域不同季节地表温度并对其进行验证. 结果表明: 石羊河流域四季地表温度变化明显, 昼夜温差很大, 其中, 春季温度分布在-13.45~29.27℃之间; 夏季温度分布在-3.75~56.29℃之间; 秋季温度分布在-10.15~32.67℃之间; 冬季温度分布在-17.15~12.75℃之间. 从地表温度空间分布上看, 在武威、 民勤、 古浪等绿洲地区地表热量丰富, 水土和植被效应显著, 热量呈圈状空间递减趋势; 在下游地区腾格里沙漠和巴丹吉林沙漠地区夏季温度最高, 祁连山东端的石羊河上游地区由于受常年积雪、 河流、 地表植被和海拔等因素影响地表温度较低. MODIS数据为宏观小流域热环境监测提供了新的途径, 且将遥感数据和地表下垫面数据相结合能提高反演精度.

Spatial Distribution of Land Surface Temperature in Shiyang River Basin Based on MODIS Data

In this paper, the calculations of some parameters such as brightness temperature, atmospheric transmittance, surface emissivity and vegetation index are discussed. Then the land surface temperatures are calculated by using MODIS split windows algorithm of NASA on the base of cloudless MODIS thermal infrared data which were collected seasonally in 2010. It is found that the distribution of land surface temperatures is very different in different seasons and different regions. In spring, the land surface temperature varies between -13.45℃ and 29.27℃. In summer, it varies between -3.75℃ and 56.29℃. In autumn, it varies between -10.15℃ and 32.67℃. In winter, it varies between -17.15℃ and 12.75℃. There are three land surface temperature zones from south to north. The temperature is very high in Wuwei, Minqin and Gulang oasis, where heat is rich and the domino effect among water, soil and vegetation are obvious. In the downstream Tengger Desert and Badain Jaran Desert, land surface temperature is extremely high in summer. Comparatively, in Qilian Mountains the temperature is very low because of perennial snow, high elevation and special land surface vegetation. In addition, MODIS data are able to supply a new way for monitoring thermal environmental change in a small basin. Especially, the derived results will be improved a lot if combine the MODIS data and surface observation.