ABSTRACT

The geostationary satellite-borne lightning measurements provide new and more effective way for lightning detection from space. In December 2016, Lightning Mapping Imager (LMI) onboard the Fengyun-4A (FY-4A) geostationary satellite was launched, which was the first satellite-borne lightning imager developed in China. Up to now, LMI has been working stably for more than 4 years to implement the continuous and effective lightning detections within China and its surrounding areas. In this study, the preliminary characteristics of measurements from LMI were analysed in detail by using the LMI data between 2018 and 2019. Moreover, the factors that affect the detection capability of LMI were investigated through an inter-comparison between the observations of LMI and International Space Station (ISS) Lightning Imaging Sensor (LIS). The results show that the LMI detection results are generally stable and reliable. The relative spatial distribution, monthly and diurnal variations, and the relative optical radiance of lightning observed by the LMI are consistent with those observed by ISS/LIS. However, the absolute values between the two sensors behave significant differences. Caused by the observation geometry, the detection results of LMI in low-latitude regions are more similar to those of ISS/LIS than in mid-latitude regions. In addition, there are some errors in the lightning radiance observed by LMI, which are possibly affected by the bright cloud background as well as radiometric calibration errors. Through targeted improvements to the onboard and ground algorithms for LMI, its detection capability can be greatly improved in future.