农业旱灾监测中的地表温度遥感反演方法——以MODIS数据为例

Methodology to retrieve land surface temperature from MODIS datafor agricultural drought monitoring in China

以目前农业旱灾监测中应用较广泛的多波段MOD IS卫星遥感数据为例,探讨农业旱灾遥感监测中所需要的地表温度反演问题,尤其是反演算法的选择、基本参数的估计和具体反演中的工作流程,为快速地进行农业旱灾监测中的水热遥感参数估计提供方法选择。虽然MOD IS有8个热红外波段用来监测地表热量变化,但波段31和32特别适用于农业旱灾监测中所需要的地表温度遥感反演。因此,在算法上,我们将选择计算过程相对简便但反演精度又很高的两因素分裂窗算法。详细地讨论了如何快速地估计分裂窗算法中大气透过率和地表比辐射率这两个基本参数。从实际应用来看,本文所提出的方法能快速地用来反演我国农业旱灾监测中所需要的农田地表温度参数,并获得很好的反演结果。

This paper takes the MODIS data extensively employed in agricultural drought monitoring as an example to present an applicable methodology for land surface temperature retrieval, with fucos on algorithm selection, parameter determination, and computation processes. Though MODIS data contain 8 thermal bands for earth observation, bands 31 and 32 are especially suitable for land surface temperature retrieval required by agricultural drought monitoring. After comparing their accuracy, two-factor split window algorithm is selected for the retrieval. Then the estimation of the algorithm＇s essential parameters for the retrieval, especially how to fastly estimate the ground emissivity and atmospheric transmittance from other bands of the same scene MODIS data discussed. Finally an experiment of applying the methodology to the real world for land surface temperature retrieval is conducted. The resuhs from our preliminary applications confirm the applicability of the proposed methodology in retrieving surface temperature parameters from MODIS data required for agricultural drought monitoring in China.