Characteristic of Short‐Duration Heavy Rainfall and Environmental Parameters

Utilizing ERA5 monthly averaged data from 1981 to 2022, ERA5 hourly data from 2018 to 2022, and observed hourly precipitation data at the airports of the Civil Aviation Flight University of China (CAFUC), the variation characteristics of short‐duration heavy rainfall (SHR) and the environmental conditions of each synoptic category were studied by classifying large‐scale synoptic circulations related to SHR. The results indicated the following: Synoptic circulation was classified into four categories for the 71 SHR selected based on the criteria: vortex (14 cases), low‐pressure trough (29 cases), subtropical high (26 cases), and other categories (2 cases). The average precipitation amount (PA) and precipitation frequency (PF) increased from 00:00 on the day of the SHR to 00:00 the next day, peaking at night, with the largest values in the vortex category and peaking earlier than the other two. The average precipitation intensity (PI) was largest in the subtropical high (9.3 mm/h), smallest in the low‐pressure trough (6.8 mm/h), and closed in the daytime and nighttime in the vortex. For the four thresholds of ≥0.1, ≥10, ≥20, and ≥50 mm/h, the average PA and PF of nighttime were larger than the daytime, the vortex was the largest, and the peak time was shifted forward between the thresholds, while shifted backward in the low‐pressure trough. Under the three synoptic categories, the increase in PA was mainly due to the contribution of increased PF, whereas the impact of PI was relatively small. Before the SHR, the vortex category had better moisture and dynamic uplift conditions than the low‐pressure trough and subtropical high categories, reflecting the dynamic nature of the vortex. Atmospheric conditions were the greatest at the subtropical high, indicating the thermal nature of the subtropical high. A K index greater than 31 was necessary for an SHR event at the CAFUC airports.