ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Study on Characteristics and Forecasting Factors of Flash Heavy Rain in Beijing Daxing International Airport Region
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Abstract:
To enhance the forecasting capability for flash heavy rain (FHR) in the Beijing Daxing International Airport (PKX) region, this study utilizes minute- and hourly-level data from May to September during 2014—2023, combined with ERA5 reanalysis data, to classify circulation patterns and analyze the precipitation and then temporal-spatial distribution characteristics and environmental conditions. The results show that FHR processes are classified into five circulation patterns, listing in descending order of their percentage as follows: the Mongolian Cyclone and Trough Type, the Western Pacific Subtropical High Edge Type, the Interaction Type of Westerly Trough and Western Pacific Subtropical High, the Huang-Huai Cyclone Inverted Trough Type, and the Northeastern China Cold Vortex Rear Type. The annual average frequency of FHR is relatively higher in the eastern region near PKX, showing a fluctuating but upward trend over the past decade. FHR events are most frequent in July and August, with July accounting for more than half of the occurrences. The diurnal variation exhibits a unimodal distribution, peaking at 22:00—23:00 BT, with durations generally ranging from 40 to 80 min. The Western Pacific Subtropical High Edge Type, the Interaction Type of Westerly Trough and Western Pacific Subtropical High, and the Northeastern China Cold Vortex Rear Type display distinct temporal characteristics, with the former two being predominantly nocturnal and the latter occurring more frequently in the afternoon. Intense flash heavy rain (≥50 mm·h?1) primarily occurs under Western Pacific Subtropical High Edge Type, and Mongolian Cyclone and Trough Type. Significant differences are observed in the environmental conditions under different circulation patterns. The Western Pacific Subtropical High Edge Type, Interaction Type of Westerly Trough and Western Pacific Subtropical High, and the Huang-Huai Cyclone Inverted Trough Type are characterized by abundant moisture, with total precipitable water vapor exceeding 50 mm and high convective available potential energy (CAPE), whereas the Huang-Huai Cyclone Inverted Trough Type exhibits strong moisture convergence despite weaker thermal instability, often featuring boundary-layer easterly jets that sustain precipitation. The Northeastern China Cold Vortex Rear Type, despite limited column moisture, favors localized heavy rainfall through strong low-level warm advection and significant upper-lower atmospheric temperature differences, favoring the development of localized heavy rainfall.
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