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利用傅里叶变换红外光谱仪对绿洲盐渍化土壤进行野外测量,采用光谱平滑迭代法对温度和发射率进行分离,得到了盐渍化土壤的热红外发射率数据。通过对盐渍化土壤发射率光谱的特征分析,得出8～13μm土壤发射率随盐分含量的增加而减小,发射率光谱对盐分因子的响应在8～9.5μm较敏感。分析了原始发射率光谱、一阶导数、二阶导数和标准化比值与含盐量之间的相关性,表明土壤发射率与含盐量呈负相关关系,发射率一阶导数与含盐量的相关性最高,相关系数最大为0.724 2,对应波段为8.370 745～8.390880μm。建立了土壤发射率一阶导数与盐分含量的二次函数回归模型,模型拟合的决定系数为0.741 4,验证结果的均方根误差为0.235 5,说明利用热红外发射率光谱反演土壤盐分含量的方法可行。
Field measurements of oasis salinized soils were carried out by Fourier transform infrared spectroscopy, and the temperature and emissivity were separated by spectral smoothing iteration method. The thermal infrared emissivity data of salinized soils were obtained. According to the characteristic analysis of emissivity spectrum of salinized soils, the emissivity of 8 ~ 13μm soil decreased with the increase of salinity, and the response of emissivity spectrum to salinity factor was sensitive at 8 ~ 9.5μm. The correlation between the original emissivity spectrum, the first derivative, the second derivative and the normalized ratio and the salinity was analyzed. The results showed that there was a negative correlation between soil emissivity and salinity, the first derivative of emissivity and salinity The correlation was the highest with a correlation coefficient of 0.724 2 and the corresponding band was 8.370 745 ~ 8.390880μm. The quadratic function regression model of soil emissivity first derivative and salt content was established. The coefficient of determination of model fitting was 0.741 4, and the root mean square error of validation result was 0.235 5, indicating that the use of thermal infrared emissivity spectrum to retrieve soil salinity Content of the method is feasible.