腾格里沙漠东南缘不同固定程度沙地土壤表层水分时空变化遥感分析

doi:10.7522/j.issn.1000-694X.2015.00029

摘要/Abstract

摘要：

土壤表层水分是固沙植被生长的主要水分来源,其时空变化格局决定了固沙植被的稳定性和演替方向。整合被动微波和光学数据的时空分辨率优势建立模型、反演土壤表层水分,可为不同固定程度沙地固沙植被稳定性评价提供科学依据。以腾格里沙漠东南缘为研究区,选取2003-2011年生长季(5-9月)AMSR-E土壤水分产品与MODIS数据,利用归一化植被指数NDVI、地表温度T_s,采用多元回归的方法,将空间分辨率为0.25°的AMSR-E土壤水分数据降尺度为每月的1 km平均表层土壤水分的时间序列数据,结合沙丘类型数据,分析了不同沙丘类型下土壤水分的时空异质性。结果表明:流动沙地的土壤水分空间分布与整个区域的差异性高于半固定沙地和固定沙地,而在极端干旱年份,研究区的整体分异不大,但同一类型间,固定沙丘空间差异明显高于半固定沙丘和固定沙丘;3种沙地类型表层土壤平均含水量在不同月份具有相似的变化规律,即土壤含水量5-9月呈抛物线形状,先下降后上升,7月达到最低,从同一月份不同沙地类型看,研究区表层土壤水分含量依次是固定沙地>半固定沙地>流动沙地;年际土壤水分在流动沙地和半固定沙地随降雨的变化而变化,而固定沙地基本不变。

关键词: 降尺度, 区域尺度, 表层土壤水分, 沙地类型

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 (T_s) 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

中图分类号:

S152.7

李森, 颜长珍, 谢家丽. 腾格里沙漠东南缘不同固定程度沙地土壤表层水分时空变化遥感分析[J]. 中国沙漠, 2016, 36(3): 734-740.

Li Sen, Yan Changzhen, Xie Jiali. Space-temporal Analysis on Surface Soil Moisture Data in the Different Dunes of the Southeast Margin of the Tengger Desert[J]. JOURNAL OF DESERT RESEARCH, 2016, 36(3): 734-740.

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