Sensitivity Analysis of Severe Convection Conditions Triggering Thunderstorms Based on Various Slope Inclinations and Aspects in Complex Terrain

Based on the minute-by-minute ADTD—2 lightning monitoring data in the southeastern coastal area of China from April to September 2015 to 2022 and the hourly reanalysis data of ERA5 of the European Center for Medium-Range Weather Forecasts, the southeastern coastal area of China is divided into different geomorphic elements according to slope and aspect by using the climate composite statistical analysis method, and the strong convective conditions such as water vapor conditions, unstable energy and vertical wind shear generated by thunderstorms of various types are analyzed. The results show that: (1) China's geomorphic characteristics are complex, and the strong convective conditions caused by thunderstorms under different geomorphic types are inconsistent. The water vapor conditions caused by thunderstorms under different geomorphic elements are uneven. When the slope is less than 60°, the area is affected by PWAT, CAPE, DT85 and SHEAR6, which makes it very easy to have rough thunderstorms. However, the area with a slope of more than 60° is almost unaffected by the three strong convective conditions. (2) The three strong convective conditions have no significant effect on the slope direction. Relatively speaking, PWAT is the most affected in all directions in June and September. (3) The impact of strong convective conditions caused by thunderstorms on land resource utilization is mainly reflected in time. With the beginning of the flood season, PWAT, CAPE and DT85 all show a trend of first increasing and then decreasing, while SHEAR6 has been decreasing. The vertical wind shear is the largest in April and May, the water vapor conditions and unstable energy are the main factors in June and July, and the PWAT is the main factor in August and September. In summary, the convective instability energy of thunderstorms caused by different geomorphic elements presents a single peak with the month, and the unstable energy generated by thunderstorms shows a downward trend with the increase of terrain height. The convective conditions that trigger thunderstorms are more likely to appear on cultivated land, grassland and water surfaces.