Comparison of Lightning Detection Between the FY‐4A Lightning Mapping Imager and the ISS Lightning Imaging Sensor

The Lightning Mapping Imager (LMI) onboard Fengyun‐4A (FY‐4A) is the first Chinese lightning detection sensor in geostationary orbit. This study presents the lightning characteristics observed by the FY‐4A LMI in its first year, and then observations from the Lightning Imaging Sensor (LIS) onboard the International Space Station (ISS) are used to validate the performance of the LMI sensor. LMI lightning events are defined by the pixel's luminosity exceeding the threshold radiance. During the first year of operation, LMI events revealed a reasonable geographical distribution. The diurnal cycles of LMI event/background/threshold radiance are in general agreement with the later afternoon peaks in previous findings. However, the LMI events that occurred around the LIS flash time and in the LMI observation field‐of‐view show a slightly delayed peak at around 1900 LST. This peak can be shifted closer to LIS's results after removing LMI events with event radiance lower than 300 μJsr−1m−2μm−1, suggesting that a larger threshold radiance value is needed to qualify some of these LMI events. Finally, LIS lightning groups were matched with LMI lightning events using different temporal and spatial collocation criteria. The detection efficiency is defined by the fraction of LIS groups detected by LMI to assess LMI's performance. The LMI detection efficiency relative to LIS was found to be regionally dependent and lower in the daytime than at nighttime. These results contribute to applications of LMI lightning observations in storm research and provide suggestions for further algorithm improvement.