Inversion Of Mid-infrared Data Reflection Information

This paper describes the research status of mapping snow cover and mid-infrared data reflection information on the Qinghai-Tibet Plateau,and introduces the basic overview of the Qinghai-Tibet Plateau.In this paper,the reflection information of mid-infrared data is mainly studied because the medium-resolution snow-bearing sub-pixel mapping research after 1998 is relatively mature.In order to extend the timeline of the snow-bearing sub-pixel mapping,the earlier AVHRR/2 data was selected,but the data covered only two bands in the visible light range,which made the optical information in the snow-bearing sub-pixel mapping process somewhat insufficient.If you can increase the optical band of AVHRR/2 data,it will improve the accuracy and reliability of the information based on AVHRR/2 data identification.The mid-infrared band of AVHRR/2 data contains reflected energy and emission energy,so as long as the mid-infrared band The inverse of the reflected energy in the reflection is equivalent to adding an optical band to the AVHRR/2 data,which improves the accuracy and reliability of the snow-bearing pixel mapping study.In this paper,we present an energy radiative transfer equation that uses mid-infrared band of AVHRR/2(3.55?m-3.93?m),by which the surface reflectance of mid-infrared band of AVHRR/2 can be calculated and then improves the accuracy of snow sub-pixel mapping.Specifically,the contents mainly covered the following four aspects:1.The MODTRAN software is used to simulate the radiative transmission process of the mid-infrared band in atmosphere.When simulating the transmission process,various atmospheric parameters should be input.Among them,water vapor is the most important parameter,which could be calculated from NCEP data in our study.After the atmospheric parameters are determined,we could obtain the atmospheric radiation,atmospheric transmittance and other data by simulation.2.The land surface temperature can be calculated by using split-window algorithm.In the simulation process of radiative transmission,land surface temperature is deemed to be an important factor.The objects are classified according to NDVI threshold,and the emissivity of different objects is determined by empirical algorithm.Then we could obtained the land surface temperature based on split-window algorithm.3.On the basis of land surface temperature,the radiation energy of object in mid-infrared band can be calculated.We can get the emission energy of land surface in the mid-infrared band by differential summation for the Planck function based on different land surface temperature.4.The surface reflectance is calculated.In view of the Energy radiation transfer equation,we ultimate determine the surface reflectance by inputting radiation energy values.