遥感物理-红外遥感2009-3详解.ppt

第六章 热红外遥感;第三节 陆面温度遥感;1. 陆面温度遥感反演面临的主要问题 非同温混合象元占绝大多数，对这样的象元而言，定义象元的有效平均温度也比较困难，关于这类非同温混合象元的陆面温度遥感问题需要专门讨论。 对纯象元陆面温度的遥感问题，由于陆面目标的比辐射率明显小于“1”，所以需要考虑大气下行辐射的贡献与干扰。 陆面目标的比辐射率往往受物理状况（如土壤比辐射率随土壤含水量而变），表面粗糙度、地表起伏造成传感器对地表实际视角的起伏等因子控制，所以一般只能作为未知量，不能事先设定。; 大气效应纠正 地表真实辐射亮度值 地表真实比辐射率值 ;? ;? ;? ;? ;? ;? ;? ;? ; 为了提高分裂窗口法反演地表温度的精度，近年来的工作越来越把大气状态作为温度反演中的信息。而放弃那种建立对任何大气模式都适用的“全能”模型。 Francois和Ottle(1996)指出在 已知的条件下，考虑水汽修正可使地表温度反演的精度达到0.2~0.1K。这以Francois(1996)，Wan (1996)，Sobrino(1994)所作的工作为代表。 ;? ;6.3.1 陆面温度遥感反演概述 6.3.2 陆面地表温度的分裂窗反演算法 6.3.3 地表比辐射率的遥感反演方法;1. Quantity Measured by Radiometry from Space ;Spectral Radiance at Satellite Level at viewing angle ;During the nighttime or for channels in the 8-14mm;Influence of e and the atmosphere on Ts measurement;Influence of e and the atmosphere on Ts measurement;Influence of e and the atmosphere on Ts measurement;Temperature Correction (Deficit) due to Absorption and Emission of Atmosphere ;and are constant for a reference temperature ;;;2. Multi-channel (Split-Window) method;Land Surface Temperature Retrieval –Local Split Window;Land Surface Temperature Retrieval –Local Split Window An algorithm for AVHRR/NOAA14;3. Determination of Atmospheric Water Vapor;? . ;Relationship between and ;;Principle of Method;Emissivity ratios of channels 11mm and 12mm of ATSR2 calculated from the hemispheric reflectances measured in laboratory by Salisbury and D’Aria [1992] for different types of natural surfaces. ;Relationship between transmittance ratio and W ;Angular dependence of regression coefficients; W values retrieved from satellite data are comparable in magnitude with W observed by radiosoundings, g/cm2, g/cm2;第三节 陆面温度遥感;1. Why Measure Surface Emissivity e;How to Get Surface Emissivity e (1);How to Get Surface Emissivity e (2);Using emissivity database Needs: a) Images classification from VIS/NIR and TIR images