Research And Analysis Of GF-4 Cross Radiation Calibration Technology Based On MODIS And LandSat8

GF-4 satellite is the only geosynchronous orbiting remote sensing satellite in China’s high-resolution earth observation system,which is used in the field of environment and forest fire monitoring.Since the launch of GF-4,uncertainties in orbital space and aging of components have caused some radiation deviations in the visible and near infrared bands of GF-4.However,at present,only one site radiometric calibration is carried out annually for GF-4 satellite.Under this background,how to improve the data accuracy of GF-4 satellite and expand the application field and scope of data by using ground data processing technology is an important research content of this paper.In this paper,the cross-radiation calibration of PMS in visible and near infrared bands and IRS in thermal infrared bands of GF-4 is carried out by using MODIS and LandSat8 as reference sensors.The main work is as follows:1.For the four spectral bands of GF-4 near and visible light,this paper uses MODIS and LandSat8 data as the reference image and Dunhuang Radiation Correction Field as the test area for cross-radiation calibration.The results show that the calibration errors of both visible and near infrared bands of MODIS are less than 10%,while those of visible and near infrared bands of LandSat8 are less than 8%.The calibration accuracy of MODIS is close to the official calibration coefficients and meets the quantitative requirements of remote sensing.2.For the special spectrum of GF-4 thermal infrared band IRS,a dual-band spectral matching method is proposed.In this paper,using MODIS as reference sensor and Qinghai Lake as calibration radiation field,the calibration coefficients calculated by five spectral matching methods of single-band and double-band method are compared with the official calibration coefficients.The analysis shows that the weight factor calculated by the central wavelength distance method in the dual-band method has the best calibration accuracy.However,the use of band 20 in the single-band method is equally important for fast calculation of correction coefficients and can provide correction coefficients with similar accuracy.The brightness temperature difference is calculated by using the coefficients obtained by the five methods and the official calibration coefficients.The brightnesstemperature difference obtained by the central wavelength distance method is mainly between0.3K and 0.6K.The validity and feasibility of the dual-band method are also verified by multi-site verification.Therefore,the research in this paper can provide an effective alternative method for IRS calibration of GF-4 with similar accuracy to site calibration.