The Spatial Pattern of Soil Moisture in Northern Tibet Based on TVDI Method
Using enhanced vegetation index (EVI) and land surface temperature (LST) dataset derived from TERRA/MODIS synthetic products MOD13 A2 (16-day composite, DOY 209 in 2010) and MODll A2 (8-day composite, DOY 209 and 217 in 2010), the LST-EVI two-dimensional characteristic space was constructed, and then TVDI (temperature-vegetation drought index) was extracted to indicate the top-soil moisture of northern Tibet. Furthermore, the simulated soil moisture was verified by synchronously measured data in the field. The two groups of data showed a strong relationship and the correlation coefficient got through the 0.05 significance level. Then the spatial pattern and heterogeneity of soil moisture in the studied area were further analyzed, and the results showed: (1) the TVDI values of pixels in northern Tibet proved to have a statistically normal distribution,and the soil moisture in eastern region, central region and western region respectively showed wet, normal and dry situations; (2) evident difference in soil moisture existed in different climatic zones, and the soil moisture in the mountain and valley-in-valley structured Nagqu sub-arctic and sub-humid zone was the highest and that in southern Qinghai sub arctic and semiarid zone was the lowest; (3) the spatial distribution of soil moisture in the area was obviously affected by the altitude. The soil moisture in the region below 4500 m showed a negative correlation with the altitude and the correlation was positive in the region higher than 4500 m.
NETL
NSTL
万方数据
维普
