Abstract
AbstractDuring the period from June 30th to July 6th, 2016, a heavy rainfall event affected the middle and lower reaches of the Yangtze River valley in eastern China. The event was characterized by high‐intensity, long‐duration (lasted more than 6 days) precipitation and huge amounts (over 600.0 mm) of rainfall. The rainfall moved eastward from the Sichuan basin to the middle Yangtze River valley during the first 2 days, then Mei‐yu front formed and circulations became more “quasi‐stationary”. During the second‐phase, successive heavy rainfall systems occurred repeatedly over the same areas along the front, leading to widespread and catastrophic flooding. In this study, limited‐area convection‐permitting models (CPMs) covering all of eastern China, and global‐model simulations from the Met Office Unified Model are compared to investigate the added values of CPMs on the veracity of short‐range predictions of the heavy rainfall event. The results show that all the models can successfully simulate the accumulated amount and the evolution of this heavy rainfall event. However, the global model produces too much light rainfall (10.0 mm/day), fails to simulate the small‐scale features of both atmospheric circulations and precipitation, and tends to generate steady heavy rainfall over mountainous region. Afternoon precipitation is also excessively suppressed in global model. By comparison, the CPMs add some value in reproducing the spatial distribution of precipitation, the smaller‐scale disturbances within the rain‐bands, the diurnal cycle of precipitation and also reduce the spurious topographical rainfall, although there is a tendency for heavy rainfall to be too intense in CPMs.
Highlights
The Mei-yu season is the second major stationary phase of the summer monsoon in East Asia (Tao, 1987; Ding, 1992; Ding and Chan, 2005; Zhou et al, 2009; Luo et al, 2013)
We aim to find the added values of convection-permitting models (CPMs) in reproducing the spatial distribution of precipitation, precipitation structure, the diurnal cycle of precipitation and topographical rainfall, compared with global driving model (UM-GL)
The heaviest rainfall was centered on the YRB-ML and covered a wide area which delineates the mean position of the monsoon front during the heavy-rainfall period (Figure 1a)
Summary
The Mei-yu season (the period from mid-June to mid-July) is the second major stationary phase of the summer monsoon in East Asia (Tao, 1987; Ding, 1992; Ding and Chan, 2005; Zhou et al, 2009; Luo et al, 2013). Because of its quasi-stationary characteristics, the Mei-yu front can act as a “guide” for these storms, heavy rainfall events often occur and propagate eastward repeatedly in a narrow latitudinal corridor over the YRB-ML (Chen et al, 1998; Ding and Chan, 2005; Ninomiya and Shibagaki, 2007; Xu et al, 2009), thereby enhancing their capacity for causing catastrophic flooding (Doswell et al, 1996). The event left about 237 dead and 93 missing, affected more than 10 provinces (Hubei, Anhui, Jiangsu, Jiangxi, Hunan, Chongqing and other provinces) and resulted in over $22 billion in damage (Zhou et al, 2018), making it a high-impact weather event of international significance
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