Characteristics and Preliminary Causes of Extremely Persistent Heavy Rainfall Generated by Landfalling Tropical Cyclones Over China
Haisheng Liu, Xiaogang Huang, Jianfang Fei, Chi Zhang, Xiaoping Cheng
Abstract
Abstract Extremely persistent heavy rainfall (EPHR) generated by landfalling tropical cyclones (LTCs) can cause destructive natural disasters. In this study, hourly precipitation data and best‐track data set for 2009–2019 are used to investigate the basic characteristics and preliminary causes of LTC‐generated EPHR over China. Using the relative threshold method, heavy precipitation lasting more than 7 hr is defined as EPHR. The result shows that most of the EPHR events occur in the south and southeast China, especially in the northwest of Hainan Island and the coastal areas of Zhejiang. The maximum duration of EPHR can reach 13 hr with a maximum cumulative rainfall of 668.9 mm. EPHR in the intermediate region (150–300 km away from the tropical cyclone (TC) center) of the LTCs tends to have a higher frequency and greater intensity, and the development process of the EPHR events exhibits a significant asymmetrical feature. Although EPHR accounts for a relatively small proportion (29.4%) of duration in EPHR events, it accounts for a large proportion (61.0%) of cumulative precipitation. The combination effects of topographic forcing and tracks of the TCs directly determines the high incidence areas of EPHR. And the preliminary causes of EPHR are mainly due to the upliftment or blocking effects of the topography. In addition, the translation speed and intensity of the TC can also restrict the generation of EPHR. In general, a stronger and slower TC is more likely to cause EPHR events when it passes through north of Hainan Island or makes landfall at Zhejiang‐Fujian area.