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Schlagwörter:
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Zusammenfassung:
The Fengyun-4A (FY-4A) Lightning Mapping Imager (LMI) is the first satellite-borne lightning imager developed in China, which can detect lightning over China and its neighboring regions. In this study, the LMI-observed temporal and spatial variations of lightning activity were compared with Lightning Imaging Sensor (LIS) and World Wide Lightning Location Network (WWLLN) observations and the observational characteristics of the LMI were revealed. Moreover, the effects of the response characteristics of the LMI instrument on its detection capability were studied and the factors that may affect LMI detection were discussed.
Comparisons indicate that the spatial distributions of lightning activity among three platforms are consistent. However, among the 16 sub-regions of the LMI, the southern sub-regions are more conducive to the identification of lightning events. The southern regions have the highest coincidence ratio (CR) with LIS, followed by the northeast region, and the northwest region has the lowest CR. Lightning density detected by the LMI during daytime hours is lower than that detected by LIS, which may be due to the large cloud background noise and the raise of the signal filtering threshold during daytime. The peak value of diurnal variation varies largely among the 16 sub-regions, due to the difference in response characteristics between sub-regions and solar zenith angles. Additionally, the proportion of brighter, larger, and longer-duration flashes detected by the LMI is significantly greater than that of LIS, which are related not only to the instrument performance but also to the onboard and ground data processing of the LMI.
