Spatiotemporal patterns of long series of cloud-to-ground lightning in Beijing and its cause

Previous studies on the climatic characteristics of lightning activity in Beijing are sparse due to the lack of long-term, continuous and stable lightning location data. In this paper, the long series of lightning location data during 2009–2018 were applied to reveal the spatiotemporal distribution of cloud-to-ground (CG) lightning in Beijing. The spatial characteristics were low west and high east, and the temporal characteristics were frequent in summer. In the complex terrain areas of northeast Beijing, there was a positive relationship between CG density and altitude, with the correlation coefficient higher than 0.8. The northeastern trumpet-shaped terrain had the forced lifting effect on thunderstorms, forming lightning-intensive areas of 500 km2. In addition, urban heat island (UHI) effect provided the necessary thermal conditions for the development of thunderstorms, forming lightning-intensive areas in the built-up areas, with the highest value of CG flash density exceeding 6 fl/km2. Note that the lightning-sparse areas in the urban center exhibited a distinct barrier effect on the spatial patterns of summertime CG lightning in the built-up areas, which was mainly modulated by the type of synoptic background. •The long series of lightning location dataset were necessary for studying the patterns of cloud-to-ground (CG) lightning.•The forced lifting effect of terrain on CG lightning was significant.•Urban heat island effect played an important role in forming lightning-intensive areas in the built-up areas.•The strong synoptic background was an essential condition for the distinct barrier effect over the built-up areas.