| With the development of thermal infrared remote sensing technology,a large number of earth observation satellite remote sensors with thermal infrared band detection capabilities have been launched.During the orbit operation of the satellite remote sensor,in addition to using the onboard blackbody for on-board calibration,it is also necessary to carry out radiometric calibration in test-site to verify or replace the on-board calibration results to ensure the accuracy of the data products.At present,the radiometric calibration in test-site of the thermal infrared band of satellite remote sensor,mainly obtains the thermal infrared radiation characteristics of the site through manual field campaigns.This method of measuring is expensive,the efficiency is low,is limited by factors such as weather conditions,is difficult to guarantee the calibration frequency and amount of data effectively,unable to provide timely observation data for analyzing the decay of the remote sensor.The research on the automatic calibration method of the satellite infrared remote sensor thermal infrared band site has important application value for improving the timeliness and accuracy of radiometric calibration in test-site of the satellite infrared remote sensor thermal infrared band.In this paper,combined with the development trend of radiometric calibration in test-site in the thermal infrared band of the satellite remote sensor,the technical process of thermal infrared band radiation calibration is improved.designed and developed a multi-channel self-calibration infrared radiometer(Muli-channel Self-calibrated Infrared autonmous Radiometer,MSIR).The thesis completed the research work in the following aspects.In order to design a reasonable automatic site calibration process,the accuracy of obtaining different physical parameters in the process of site radiative calibration was compared,and a technical process of site automatic calibration based on temperature-based method was designed.MSIR was used to obtain the downward radiance and site radiance,combined with the multi-channel temperature and emissivity separation algorithm to obtain site temperature and emissivity,and the optimal offset method was used to obtain site hyperspectral emissivity data.With the help of the reanalysis data provided by NCEP of the United States,the atmospheric temperature and humidity pressure profile was obtained,and the equivalent radiation brightness at the entrance pupil of the satellite was calculated by combining with the radiation transmission model.The relation between the received radiation brightness and the output signal value of the synchronous observation remote sensor is established to realize the radiometric calibration of the thermal infrared band of the transit remote sensor.Compared with the conventional calibration method,the calibration process has the characteristics of high frequency,high time and high applicability,avoids the radiation measurement error caused by human factors,and reflects the influence of atmospheric downward radiation and site true emissivity on the temperature of the inversion site.MSIR with automatic observation ability was developed to meet the requirement of obtaining the radiance of the site automatically.The device shall have the following features:1)The design of the gold-plated reflector driven by an electric motor realizes the measurement of atmospheric downgoing radiation of 0°?90° elevation Angle and surface radiance,providing a technical means to eliminate the influence of atmospheric downgoing radiation on the inversion of surface temperature.2)The filter wheel is adopted to realize the automatic setting of 6 spectral channels.Combined with IMTES algorithm,the site temperature and emissivity can be obtained,providing two key factors for the absolute radiometric calibration of thermal infrared band of satellite remote sensor.3)Two blackbodies with temperature control accuracy better than 0.04k and 0.05k respectively,emissivity higher than 0.994 and stability better than 0.0014 are built into MSIR for internal radiometric calibration detectors,effectively eliminating the influence of internal background radiation on radiometric measurement,and calibration uncertainty less than 0.143%.The laboratory calibration experiment of MSIR was carried out.The two internal calibration blackbodies of MSIR were calibrated by using non-point source blackbodies as the standard radiation source.It was verified that the temperature control accuracy of the two internal calibration blackbodies was better than 0.04 K and 0.05 K respectively,and the emissivity was higher than 0.994.Radiation calibration experiments of MSIR internal detector were carried out by using non-point source blackbody and MSIR internal blackbody as calibration radiation sources.The relative deviation of the responsiveness slope and the intercept of the two methods were<1%and<0.2%respectively,indicating that the two methods with blackbody as the radiation source had good consistency.The calibration uncertainty of MSIR was analyzed.The results showed that the radiation calibration uncertainty of non-point source blackbody was less than 0.122%,and the uncertainty of equivalent radiation temperature measurement was less than 0.15 K(@300 K,11 ?m).The built-in boldbody radiometric calibration uncertainty is less than 0.143%,and the equivalent radiometric temperature uncertainty is less than 0.196 K(@300 K,11 ?m).It is verified that the MSIR self-calibration system has the same calibration accuracy as the laboratory calibration method and meets the requirements of the radiation measurement accuracy of the field observation equipment in the thermal infrared band of satellite remote sensor. |
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