基于干旱区地面实测热红外光谱的土壤含水量反演研究

A Study on Inversion of Soil Moisture Based on Measured Ground Thermal Infrared Spectrum in Arid Area

土壤水分在干旱地区生态系统中起着重要的作用,同时土壤含水量是确定土壤干旱的重要参数。通过分析野外和室内实测土壤发射率光谱特征参数与含水量之间的关系,采用光谱特征分析参数提取反演土壤含水量的最佳敏感波段,发现波长在9.480 2~9.790 1μm土壤含水量对其发射率最为敏感。根据最佳敏感波段的范围,模拟MODIS,ASTER,HJ-1B卫星的热红外波段,对波段及波段比值与土壤含水量进行回归分析,得出波段比值的线性模型可有效地反演出土壤的含水量。然后对该模型进行验证分析,确定模拟ASTER卫星传感器的12和14两个热红外波段的发射率比值与土壤含水量的线性关系,其反演精度更高。建立了适合研究区的土壤热红外发射率与含水量之间的反演模型。

Soil moisture plays an important role in arid ecological system, and soil moisture content is an important parameter in determining soil drought. We analyzed the relationship between the spectral characteristic parameters of emissivity and the soil moisture content that were measured in field and laboratory, and extracted the best sensitive band of inversed soil moisture content by the parameters from spectral characteristic analysis, it was found that the wave length were in 9. 480 2^-9. 7901 μm and the soil moisture content was the most sensitive to its emissivity. Based on the scope of the most optimal sensitive waveband, the thermal infrared wavebands of MODIS, ASTER and HJ-1B Satellites were simulated, a regression analysis was made for waveband, waveband ratio and soil moisture content, and a linear model of waveband ratio was ultimately constructed, which can effectively deduce soil moisture content. The model was verified so as to find the linear relation of soil moisture content with the emissivity of thermal infrared bands 12 to 14（simulated ASTER satellite sensor）. The inversion is so precise that an inversion model applicable to the relation of infrared emissivity and soil moisture content in the studied area was established.