利用NOAA AVHRR资料提取的归一化植被指数 (NDVI)和陆地表面温度 (LST) ,构建NDVI Ts 特征空间 ,依据该特征空间设计的温度植被旱情指数作为旱情指标 ,对中国 2 0 0 0年 3月和 5月各旬的旱情进行了研究。研究结果表明在 2 0 0 0年 3月和 5月的重旱区主要分布在中国西北地区 ,在华北和华南的部分地区也有较大范围的分布 ,3月和 5月的全国重旱面积分别为 6 7 2× 10 4km2 和 12 6 1× 10 4km2 ;通过与各气象站测定的表层 10cm土壤重量含水量 (θ)数据进行相关性研究表明 ,利用综合了植被覆盖信息和陆地表面温度信息的TVDI旱情指标能够较好地反映表层土壤水分变化趋势 ,作为旱情评价指标是合理的 ;对TVDI随NDVI和Ts 变化的敏感性评价结果表明 ,以陆地表面温度为基础的旱情指标相对比以植被指数为基础的旱情指标更合理。

Land surface temperature derived from brightness temperature dataset and NDVI dataset were used to construct the NDVI / Ts space，from which a dryness index—temperature / vegetation dryness index（ TVDI）was suggested. The dryness index that combines the land surface temperature with vegetation spectral index is computationally straightforward because it is based on the information derived from satellite data only. Using the TVDI，the surface moisture status in China in March and May in 2000 was studied. The results showed that the severe drought was mainly distributed in North-western China and part of North China and South China；the severe drought area enlarged from about 67 × 104km2 in March to 126 × 104km2 in May. TVDI spatial pattern was compared with the measured topsoil moisture from the observatories around China with the linear regression method. A negative linear correlation between TVDI and the measured soil moisture was found，thus TVDI ’s validity in evaluating drought was verified. Afterward，the sensitivity of TVDI to NDVI and Ts was evaluated. The results show that the TVDI are more sensitive to the land surface temperature than to NDVI and land surface temperature have more drought information than NDVI which lead to the conclusion that dryness indexes based on land surface temperature are more reasonable than the ones based on NDVI .