On-orbit performance of Fengyun-4A advanced geosynchronous radiation imager

Abstract

The performance of the Advanced Geosynchronous Radiation Imager (AGRI) onboard the Fengyun-4 (FY-4) satellite was evaluated. The results showed that its performance has approached the international advanced level of similar instruments. A wavelet filter was designed to filter the striping noises of the AGRI, which come from the inconsistency of the spectrum and thus varies with the observed target. The non-uniformity of the whole image was evaluated by weighting the probability variance of its count values. After filtering, the infrared image of the AGRI had a uniform visual effect on a single channel, and the pattern noise was reduced to below 0.2 K, which ensures the uniformity of products such as cloud detection and sea temperature that use the infrared splitting window channels. Furthermore, the AGRI carries the surface source blackbody as the on-orbit radiation calibration benchmark and rotates the north-south scanning mirror to point to the blackbody to obtain the blackbody observation data in each infrared band. In the current mode, the infrared calibration is performed every 15 minutes. The long-term evaluation results showed that the radiation calibration accuracy of the infrared channels of the AGRI was better than 0.5 K, and some of the channels reached 0.2 K. In addition, the long-term monitoring of the sensitivity and radiative cooling of the AGRI has shown the on-orbit variation of the instrument, which provides a reference for the development of the subsequent instrument.