Objective Identification and Analysis of Warm-Sector Rainstorm with Warm-Shear Pattern over Yangtze–Huaihe River Region

This paper investigates the warm-sector rainstorm (WR) and warm-shear pattern (WSWR) over the Yangtze–Huaihe River region. Herein, the merged rain gauge-satellite gridded hourly precipitation dataset and ERA5 reanalysis data are utilized to identify the WSWR over the Yangtze–Huaihe River basin (YHRB) from 2010 to 2017 based on the WR and shear line definitions and objective identification criteria of the mesoscale rainstorm cluster, front, and shear line. A total of 1268 WR clusters were identified over the 8 years. Accordingly, 451 WSWR clusters among the total WR clusters frequently occurred over the junction of the Anhui, Jiangxi, and Hubei provinces and in the coastal areas of the Jiangsu and Zhejiang provinces. The WSWR clusters exhibited a horizontal distribution similar to the WR clusters over the YHRB. These clusters mainly occurred from mid-June to mid-July. During this period, the WSWR clusters with an average hourly precipitation of 29 mm accounted for more than 40% of the total WR clusters and gradually moved northward, consistent with the main rainfall belt migration. The WSWR cluster occurrence showed a considerable diurnal variation, with one peak from morning to early afternoon 0800–1300 BJT (Beijing time) and another after sunset (2000–2200 BJT). The maximum precipitation of the WSWR clusters was observed in the afternoon (1300–1900 BJT) and early morning (0100–0500 BJT).