Intercalibration of SVISSR/FY-2 thermal infrared channels with AIRS/Aqua channels

Abstract

The intercalibration of the two thermal infrared channels of SVISSR/FY-2 with AIRS/Aqua is developed by using an improved HSC (High Spectral Convolution) method. The improvement of HSC includes two aspects: sub-pixel spatial matching and automatic removing coarse errors of the measurement pairs. According to the viewing geometries of SVISSR/FY-2 and AIRS/Aqua, a study area with the longitude from 41.5°E to 149.5°E and the latitude from 10°S to 10°N is especially selected. To transfer the calibration coefficients from AIRS/Aqua to SVISSR/FY-2, the SVISSR/FY-2 Normalized (NOM) 1B dataset and the AIRS/Aqua 1B infrared data in the months of December 2006, September 2007, December 2007, September 2009 and May 2010 covering the study area are employed and are aggregated into the study area with the spatial resolution of 0.5°×0.5°. The measurement pairs are extracted from the aggregated SVISSR/FY-2 and AIRS/Aqua images under the following conditions: co-location, absolute solar zenith angle difference in the same day less than 2° (|▵SZA|<2°), absolute viewing zenith angle differences less than 3° (|ΔVZA|<3°), and absolute relative azimuth angle differences less than 6° (|▵RAA|<6°). The intercalibration results show that the SVISSR/FY-2 measurements are well linearly correlated with the convolved AIRS/Aqua data. On contrast to AIRS/Aqua channels, the calibration biases exist in two SVISSR/FY-2 thermal infrared channels, and the re-calibration coefficients are presented.