针对MODIS 数据的地表温度非线性迭代反演方法

地表温度是气象、水文、生态等研究领域中的一个重要参数。构建了MODIS31/ 32 波段的热辐射传输方程, 讨论了方程的数值迭代解法, 提出了针对MODIS 数据地表温度的非线性迭代反演方法, 并介绍了大气透过率和地表比辐射率这两个中间参数的估计方法。误差及敏感性分析表明,提出的方法对大气透过率和地表比辐射率都不敏感, 反演精度优于传统的线性分裂窗算法。

A Nonlinear Iterative Method for Retrieving Land Surface Temperature by Using MODIS Data

Land surface temperature(LST) is an important parameter in meteorology,hydrology,ecology and so on.This paper has proposed a nonlinear iterative method for retrieving land surface temperature(LST) from MODIS data which needs two parameters(land surface emissivity and atmosphere transmittance).At first,two radiance transfer equations for MODIS band 31 and 32 had been built,which involves two unknowns(land surface temperature and average atmosphere temperature).Because of complexity,a numerical algorithm has been developed to solve the equations using iterative approach.Then,the estimation of the two essential parameters of the nonlinear iterative method has been extensively discussed.The atmospheric transmittance can be estimated on the basis of the relationship between atmospheric transmittance and water content which can be retrieved from the visible and infrared bans of MODIS data.As MODIS image has the lower resolution,the pixels of MODIS for most natural surfaces can be viewed as composed of three land cover patterns: vegetation,bare soil and water.The composition ration of vegetation and bare soil can be estimated from NDVI,and the land surface emissivity of MODIS31 and MODIS32 can be estimated by using the land surface thermal radiation equations of composed pixel and the known emissivity of land cover patterns.Finally,the sensitivity of parameters is analyzed and the results indicate that the parameters are not sensitive to the LST retrieval method we have proposed.The retrieved LST in Jiangsu province indicated the space difference,urban heat island effect and different ground object types.