Spatiotemporal Features and Associated Synoptic Patterns of Extremely Persistent Heavy Rainfall Over China

Abstract

Extreme precipitation, which can rapidly surpass local climatological values, may lead to natural disasters such as torrents, landslides, and debris flows, causing extensive loss of life and property. Strongly affected by the East Asian monsoon, central and east China frequently experience extreme precipitation events (Zhang et al., 2017). Studies have shown that extreme precipitation tends to increase with global warming (Fischer & Knutti, 2016;Wang & Zhou, 2005;Zhai et al., 2005), causing a rise in the number of studies performed on extreme precipitation over China in recent years. Two primary methods define extreme precipitation. The first classifies extreme precipitation according to a threshold, such as the commonly used 95th percentile threshold method (Wu et al., 2019;Xiao et al., 2016;Zhai et al., 2005) and 99.9th percentile threshold method (Luo et al., 2016), as well as the fixed threshold method (Chen & Yu, 1988). The second method involves fitting an empirical function (Wu et al., 2017;Zheng et al., 2016), which is usually utilized to discuss the return period of extreme precipitation events. Before the early 21st century, due to the lack of long-term high-resolution rainfall data, researchers only had access to daily or monthly data to investigate extreme precipitation events. However, it is easy to overestimate the intensity of long-term light precipitation or underestimate the intensity of short-term heavy precipitation, limiting the availability of detailed characteristics of extreme precipitation (Trenberth et al., 2003). With the continuous refinement of observational technology, researchers can use hourly rainfall datasets to determine extreme hourly precipitation event, focusing on extreme precipitation intensity within an hour.Extreme hourly precipitation generally means that the hourly intensity reaches a certain historical threshold (e.g., 95% or 99%), and then an extreme hourly precipitation event is defined as follows: within a period of time when the station continuously observes the occurrence of precipitation (≥0.1 mm hr −1 ), at most 1-hr precipitation interruption is allowed, and at least one extreme hourly precipitation occurs (Li et al., 2013). Studies indicate that the extreme hourly precipitation event typically exhibits an asymmetrical pattern, meaning that the duration from the beginning to the peak of the precipitation is usually faster than the duration from the peak to the end of the Abstract Extremely persistent heavy rainfall (EPHR) is characterized by high rainfall intensity and long durations, which can cause destructive natural disasters. In this study, hourly merged precipitation data for 2009-2019 are used to investigate the spatiotemporal distribution of EPHR over China. Reanalysis data are used to classify synoptic patterns related to EPHR. Observations show that the EPHR process is substantially asymmetrical, occurring mostly in South China, whereas its strongest intensity takes place in North China. There is a tendency for EPHR to occur near coastal and mountainou...

Mechanisms of Ageostrophic Wind Convergence in the Boundary Layer of Coastal Warm‐Sector Extreme Heavy Rainfall in South China

“…Compared with other objective classification methods, PCT could give more realistic and physically interpretable synoptic patterns and exhibit higher temporal and spatial stability and less sensitivity to preset parameters (Compagnucci & Richman, 2008; Huth, 1996a; Huth et al., 2008). The method has been used in many studies for synoptic classification in China (Li et al., 2016; Liu et al., 2022; Rao et al., 2019; Wang et al., 2021). More details on the method can refer to Huth (1996a, 1996b).…”

“…In their definition of EPHR, the duration of hourly precipitation exceeding 20 mm at a fixed location should be at least 5 hr (although there can be an interruption of up to 1 hr). The EPHR process mostly occurs in South China, especially in the coastal area of Guangdong (Liu et al., 2022). The majority of the EPHR in this region are accompanied by southwest maritime BLJs and can be classified as WSHR (Huang et al., 2022).…”

A Comparison of Different Station Data on Revealing the Characteristics of Extreme Hourly Precipitation Over Complex Terrain: The Case of Zhejiang, China

“…Previous studies have suggested a reasonably good performance of the PCA-T in the synoptic-pattern classification in China (Bai et al, 2021;Chen et al, 2022;Liu et al, 2022). The fifth generation of the European Centre for Medium-Range Weather Forecasts atmospheric reanalysis (ERA5) data are used as the input data for the weather type classification analysis, which are hourly available at a horizontal resolution of 0.25° (Hersbach et al, 2020).…”

Evaluation and Error Source Analysis of Convection‐Permitting Forecasts for Localized Nocturnal Rainfall Over a Complex Mountainous Region in Pearl River Delta, South China

“…In addition, the GBA urban heat island effect significantly modifies the triggering and development of heavy rainfall, especially when collaborated with orographic forcings and sea breeze (Li, Luo, et al., 2021; Li, Zhao, et al., 2021; Sun et al., 2021; Xiao, Sun, et al., 2019; Yin et al., 2020). Several other factors also contribute to the occurrence of heavy rain in South China, such as the low level jet (e.g., Chen et al., 2014; Li & Du, 2021; Liu et al., 2022; Zhang & Meng, 2019) and the mesoscale boundary between cold pool outflows and moist prevailing winds (e.g., Huang et al., 2019; Li, Huang, et al., 2021; Liu et al., 2023; Wang et al., 2014).…”