TVDI在藏北地区的适用性分析

Analysis on Applicability of Temperatuer Vegetation Index in Northern Tibet Area

为研究温度植被指数(TVDI)在藏北地区旱情监测的适用性,文章利用2015年7—8月和2016年5月的MODIS数据反演了藏北地区的NDVI和EVI植被指数,并与地表温度构建关系模型,反演出藏北地区的土壤水分。结合研究区同时段野外实测土壤相对湿度数据,对TVDI-NDVI和TVDI-EVI的准确性进行评价。结果表明:TVDI-NDVI和TVDI-EVI与5 cm、20 cm的土壤水分数据呈显著相关,均可以有效地反演土壤水分,实现大面积、长时间的旱情监测;其中TVDI-NDVI的相关系数总体高于TVDI-EVI,因此TV-DI-NDVI能够更好地反映藏北地区土壤水分状况。

NDVI and EVI vegetation index were evaluated by using MODIS data from July to August in 2015 and May 2016 in Northern Tibet in order to studying applicability of temperature vegetation index(TVDI)for monitoring drought situation in northern Tibet.A relationship model was developed with structured surface temperature for inverting the soil moisture in northern Tibet.The accuracy of TVDI-NDVI and TVDI-EVI were evaluated combining with soil relative humidity data measured in field.The results showed that there are significant correlations between TVDI-NDVI,TVDI-EVI and surface soil moisture.Both TVDI-NDVI and TVDI-EVI can effectively characterize the soil moisture and achieve large-area,long-term drought monitoring well.The correlation coefficient of TVDI-NDVI was higher than that of TVDI-EVI,therefore TVDI-NDVI can better be reflecting the soil moisture status in northern Tibet.