Characteristics of warm-Season convective activity over Lushan, China

To reveal the characteristic laws of convective activities in the Lushan area during the warm season and improve the refined forecast and early warning capabilities for convective weather in this region, we used Nanchang Doppler weather radar data from April to September during 2018–2022, combined with surface observation data, gridded lake surface air temperature products from the China Meteorological Administration Land Data Assimilation System (CLDAS) and the ERA5 reanalysis data. A method based on the Barnes filter and Tracking Radar Echoes by Cross-correlation (BTREC) algorithm was adopted to analyze the spatiotemporal evolution, movement characteristics of convection during the warm season (April–September) in the Lushan area, as well as the impact of the coupling effect on convective evolution between Lushan Mountain and Poyang Lake. The results showed that the frequency and intensity of convection over Lushan and its eastern side were significantly higher than those in adjacent regions at the same latitude. Seasonally, convection frequency was relatively high from May to July (peaking in July), while intensity was stronger from July to September (peaking in August), with July featuring both high frequency and considerable intensity. Diurnally, the high-incidence period was 12:00–16:00 (Beijing Time, hereafter the same), during which convection intensity was optimal, whereas both frequency and intensity were weak at night. More than 80% of convection moved in a southwest–northeast direction: it moved faster with concentrated wind directions from April to June, and slower with increased wind direction dispersion from July to September. The coupling of Lushan Mountain and Poyang Lake drove the spatiotemporal differences in convection through dynamic (triggering by low-level convergence zones) and thermal (lake-land/valley-mountain wind circulations) mechanisms. Based on these findings, 12:00–16:00 in the afternoon was identified as a key period for severe convection early warning in Lushan, and the southwest–northeast movement direction provided a core basis for predicting the impact range of convection. The research results offer important technical support for the refined forecast and early warning of convective weather in this region.