Intercalibration of FY-4A AGRI Thermal Infrared Channels against AHI Channels Using the Double Difference Method

• Published in: IEEE geoscience and remote sensing letters Vol. 20; p. 1
• Main Authors: Jiang, Geng-Ming, Xin, Yi-Chun
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.01.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: AHI; Calibration; Channels; Coefficients; double difference method; FY-4A AGRI; Intercalibration; Northern Hemisphere; Radiation; Radiative transfer; Satellite imagery; Southern Hemisphere; thermal infrared channels; Southern Hemisphere
• ISSN: 1545-598X; 1558-0571
• DOI: 10.1109/LGRS.2022.3231289

This letter addresses the intercalibration of the thermal infrared channels 11 (8.0~9.0 μm), 12 (10.3~11.3 μm), 13 (11.5~12.5 μm) and 14 (13.2~13.8 μm) of the Advanced Geostationary Radiation Imager (AGRI) on Chinese Fengyun 4A (FY-4A) satellite against the Advanced Himawari Imager (AHI) on the Himawari 8 using the Double Difference (DD) method with the data in January and July of 2020. To transfer the radiometric calibration from AHI to FY-4A AGRI, an accurate thermal infrared radiative transfer model and intercalibration equations are constructed. The results show that the AGRI channel 12 is well calibrated, and keeps stable in the two months. However, in other AGRI thermal infrared channels, radiometric calibration biases are obviously observed, especially the AGRI channel 11, in which the calibration biases vary by hemisphere and month. The observations in the AGRI channels 13 and 14 are about 0.83 K and 0.50 K underestimated, respectively. In the AGRI channel 11, the observations are averagely 2.36 K and 4.08 K overestimated in North hemisphere and South hemisphere, respectively. Moreover, in South hemisphere, the observations in the AGRI channel 11 in the July are averagely 0.55 K warmer than those in the January. The intercalibration coefficients were obtained by linear regression, and finally the radiometric calibration biases in the AGRI thermal infrared channels were successfully removed.