TM与MODIS植被供水指数反演及对比分析

为了探讨多源卫星遥感数据针对同一地区同一时刻旱情所得植被供水指数的差异,选择我国华北地区旱灾发生频率较高、影响较广的河北地区为研究区,针对近年来干旱监测应用较为广泛的Landsat TM/ETM+和EOS MODIS数据,分别进行植被供水指数的提取,并进行两者之间的对比分析,得出以下结论:① TM VSWI (Vegetation Supply Water Index) 与MODIS VSWI之间数值上存在一定的差别,变化范围在-0.51~0.20之间。其中负值主要集中在城镇、裸地及水体地表；② 在植被覆盖区,TM的平均VSWI大于MODIS的,但两者差别不大；③ 在各种植被覆盖度条件下,TM VSWI与MODIS VSWI差值的最小值、最大值和均值均表现出随着植被覆盖度的增加,其值逐渐增大的特点。该结论可以为两种遥感数据源干旱监测的差异分析及综合应用提供重要的参考依据。

VSWI Retrieved and Compared between TM and MODIS

In order to present the difference between VSWIes (Vegetation Supply Water Index) retrieved from different remote sensing data,VSWIes abstracted from Landsat TM and EOS MODIS data of Hebei province in North China are calculated and compared. At first, NDVI (Normalized Difference Vegetation Index) and LST (Land Surface Temperature) are calculated from the two remote sensing sources respec-tively. And then VSWIes are retrieved and compared. Finally, the following conclusions are be drawn: ① On September 8,2004 in the study region,the difference between TM VSWI and MODIS VSWI is changing from -0.51 to 0.20,and the negative values are mainly happened in towns,bare fields and water bodies; ② In vegetation cover areas,TM VSWI is often bigger than MODIS VSWI,but the difference is little; ③ The minimum,maximum and average values of the difference between TM VSWI and MODIS VSWI present the same trend: the values are increasing with the increase of vegetation coverage. The conclusions of this paper are helpful for recognizing VSWIes difference between TM and MODIS and can provide important in-formation for fusion of the drought indices extracted from the two different sources.