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JOURNAL OF DESERT RESEARCH ›› 2016, Vol. 36 ›› Issue (3): 734-740.DOI: 10.7522/j.issn.1000-694X.2015.00029

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Space-temporal Analysis on Surface Soil Moisture Data in the Different Dunes of the Southeast Margin of the Tengger Desert

Li Sen, Yan Changzhen, Xie Jiali   

  1. Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China
  • Received:2015-02-06 Revised:2015-12-31 Online:2016-05-20 Published:2016-05-20

Abstract:

The surface soil moisture is the main water source of sand-fixing vegetation for growing. The temporal and spatial variations of surface soil moisture determines the stability and succession direction of sand-fixing vegetation. Through integrated the spatial and temporal resolution advantages of passive microwave and optical remote sensing data, a model for retrieving surface soil moisture was established to provide a scientific basis for the analysis of the stability evolution of sand-fixing vegetation in different fixed degree sandy lands. In this paper, AMSR-E soil moisture products and MODIS data of the study area were selected for downscaling the surface soil moisture, which covered the southeast margin of the Tengger Desert in growing period from 2003 to 2010. Using multiple regression method, NDVI (Normalized Difference Vegetation Index) and land surface temperature (Ts) have been applied to conduct analysis on AMSR-E soil moisture data that have a spatial resolution of 0.25 . As a result, a group of time series data featuring the spatial and temporal resolutions are 1 km and 1 month, respectively, was obtained. Then, combined with the spatial distribution of three dune types which are mobile dunes, semi-fixed dunes and fixed dunes, respectively, we analyzed the temporal and spatial heterogeneity of soil moisture among these three dune types. The results show that: (1) The surface soil moisture of mobile dunes are different from the whole area, which was higher than that of semi-fixed dunes and fixed dunes. And, in extreme drought years (for example 2005), the differentiation of surface soil moisture was little in the whole area. The spatial differentiation of surface soil moisture of fixed dunes was significantly higher than that of semi-fixed dunes and mobile dunes within the same type. (2) The average moisture content of the surface soil of three dunes types had similar variation. Namely, the changes of soil moisture had parabolic shape from 5-9 months, rising after the first drop in July to a minimum. (3) From different sand types in the same month, surface soil moisture content in turn is fixed dune> semi-fixed dune> mobile dune; Variation of soil moisture between years showed that mobile and semi-fixed sand was affected by rainfall, and fixed sand basically unchanged.

Key words: downscaling, regional scale, surface soil moisture, sandy type

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