ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 48 Issue 8 > 2022,48(8):963-978. DOI:10.7519/j.issn.1000-0526.2022.041001 Prev Next
Statistical Characteristics of the Hourly Heavy Rainfall Events over Anhui Province During the 2011-2018 Warm Seasons and the Associated Synoptic Circulation Patterns
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Abstract:
Using the 10 min surface rainfall observations in Anhui Province during the 2011-2018 warm seasons (May to August), the spatio-temporal distributions of hourly heavy rainfall (HHR) events during the pre-Meiyu, Meiyu, and post-Meiyu periods are comparatively analyzed. The results show that the HHR events frequently occur over the areas from Dabie Mountains (Mt.DB) to the southwest of the southern Anhui Mountains (Mt.WN). The contribution of the HHR events over the southwest and northeast of Anhui Province to the total precipitation during the warm-season reaches 30%-40%. During the pre-Meiyu period, the HHR events have a lower occurrence frequency and weaker rainfall intensity than in the Meiyu and post-Meiyu periods. The HHR events during the Meiyu period last longer and produce a larger rainfall accumulation than those during the pre- and post-Meiyu periods, while those during the post-Meiyu period have larger intensity but shorter duration. Defined according to the 99th percentile threshold, more than 60% of the extreme persistent (accumulated rainfall) HHR events take place during the Meiyu period, while more than 60% of the extreme rainfall intensity HHR events with 10 min rainfall ≥25 mm occur during the post-Meiyu period. The HHR events’ occurrence frequency peaks at 06:00 BT and 17:00 BT during the Meiyu period, but exhibits a prominent single peak at 16:00 BT during the post-Meiyu period. Based on the rotating T model of the principal component analysis, the main synoptic circulation patterns of the HHR events can be classified as the southwest vortex/shear type or front type (SP2) and northwest trough type (SP1) during the Meiyu period. The SP2 type HHR events are the major contributor to the HHR accumulation and mainly occur in Mt. DB, Mt. WN and their transition zones. HHR events of the SP1 type tend to occur in mountainous areas such as Mt.DB, Mt.WN and northeastern Anhui. During the post-Meiyu period, the two major patterns are the southern low-pressure or typhoon type (SP6) and northwest low trough type (SP1). The major contributor to the HHR accumulation is the SP6 type HHR events that occur mainly in Mt. DB and Mt. WN, while the SP1 type HHR events take place more in the north than in the south.
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