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›› 2012, Vol. 35 ›› Issue (03): 446-455.

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Estimating soil water in Northern China based on Vegetation  Temperature Condition Index (VTCI)

WANG Mingcheng,YANG Shengtian,DONG Guotao,BAI Juan   

  1. School of Geography, Beijing Normal University, State Key Laboratory of Remote Sensing Science,  Beijing Key Laboratory of Environmental Remote Sensing and Digital City, Beijing 100875, China
  • Received:2011-09-18 Revised:2011-12-27 Online:2012-05-25
  • Contact: WANG Mingcheng E-mail:wangmcyao@163.com

Abstract: Drought is one of the main meteorological disasters in Northern China and it does great harm to national economic and agriculture of China.Soil moisture is an important parameter to study the characteristics of drought.A lot of methods were developed to monitor soil moisture both in field scale and macro scale regions,and there are too many limitations for these methods to monitor soil moisture.A nearreal time drought monitoring approach called Vegetation Temperature Condition Index (VTCI) integrates land surface reflectance and thermal properties and can invert soil conditions of land surface in macro scale region more accurately.It is calculated based on the triangular space of NDVI-Ts and closely related to soil moisture.On the basis of Terra-Moderate Resolution Imaging Spectoradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) products and soil moisture observation data during 2000-2008,we employed this method to monitor land surface soil moisture of northern China.Considering the complexity of geography environment and weather characteristics in northern China,we divided the study area into four division: the North region,the Northeast region,the Northwest region and the Qinghai region,and the soil moisture between 0-10 cm during 2000-2008 were calculated separately.We extracted the intercept and slope of the “Wet edge” and “Dry edge”and calculated VTCI,and soil moisture was calculated according to the linear relationship between VTCI and observation data.The results show that land surface soil moisture is various in different regions and different time:it is lower in the northern and western regions than that in the southern and eastern regions; it is greater than 0.2 cm3/ cm3 in the Northeast and the Qinghai region and less than 0.05 cm3/ cm3 in the desert region of Xinjiang;it is high in July and August and low in March and April,September and October due to the variety of rainfall and crop water requirement;it increased from 2000 to 2001,2001 to 2002,2005 to 2006,and decreased from 2002 to 2003,2004 to 2005 in most part of the study area;the changes of soil moisture are various in different years and regions,precipitation is highly correlated to the temporal and spatial distribution of soil water.Compared with ground measurements,it shows that the inversion based on VTCI method has good precision and can monitor the drought conditions in northern China more accurately.

Key words: soil moisture, remote sensing, Vegetation Temperature Condition Index, drought

CLC Number: 

  • S127