Science and prediction of monsoon heavy rainfall

Luo, Yali; Li, Liye; Johnson, Richard H.; Chang, C. P.; Chen, Lianshou; Wong, W.C.; Chen, Jing; Furtado, Kalli; McBride, John L.; Tyagi, Ajit; Lomarda, Nanette; Lefort, Thierry; Cayanan, Esperanza O.

doi:10.1016/j.scib.2019.09.005

Cited by 14 publications

(11 citation statements)

References 17 publications

(19 reference statements)

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“…The presummer rainy season also features frequent occurrence of extremely heavy rainfall, that is, rainfall accumulations exceeding 100 mm in 1 hr and beyond 300 or even 500 mm in several hours along the coastline (e.g., Liu et al., 2018; H. Wang et al., 2014; Wu & Luo, 2016) and over the PRD urban cluster (M. Li et al., 2021; Zeng & Wang, 2022). The onset of the summer monsoon over SCS significantly influences the initiation and organization of rainstorms, as well as the amount, intensity, and diurnal variations of precipitation over South China during the presummer rainy season (e.g., Ding, 1992; Jiang et al., 2017; Z. Li et al., 2020; Luo et al., 2019), as abundant air with high‐equivalent potential temperature ( θ e ) is transported by the strengthened southwesterly monsoonal flow to South China (Chen & Luo, 2018). The later rainy season of South China often begins in late June when the major monsoon rain belt moves northward to the Yangtze and Huaihe River Basin in central East China in accordance of the northward advance of the East Asian summer monsoon (EASM) (Ding & Chan, 2005), and ends in late September.…”

Section: Introductionmentioning

confidence: 99%

Subseasonal Variations of Convective and Microphysical Characteristics of Extreme Precipitation Over the Pearl River Delta at Monsoon Coast

Luo

et al. 2023

JGR Atmospheres

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The large‐scale flows and rainfall pattern change markedly with the progression of the summer monsoon, but how the convective and microphysical characteristics of monsoon extreme precipitation vary subseasonally remains elusive. This study compares 16,844 extreme precipitation features (EPFs) among the pre‐monsoon, active‐monsoon, post‐monsoon periods, and tropical cyclone (TC) days using multisource data including dual‐polarimetric radar observations over the Pearl River Delta in South China. Results indicate that the environmental dynamics and thermodynamics significantly influence the EPFs' convective and microphysical properties. Despite the similar environmental conditions such as abundant moisture and moderate to large convective available potential energy (CAPE) under which the EPFs occur, differences among the four periods are noticed. During the pre‐monsoon period, precipitation systems are the largest in area but their EPFs are the least frequent and have the lowest raindrop concentration, likely due to the colder and drier environment with large vertical wind shear (VWS). The onset of the summer monsoon increases both the frequency and the convective intensity of EPFs, leading to an increase in raindrop size, which is consistent with the substantial increases of CAPE and moisture during the active‐monsoon period. The EPFs share similar convective intensity and raindrop size distribution (RSD) between the post‐monsoon and the active‐monsoon periods, although the post‐monsoon EPFs are slightly less frequent and have a smaller horizontal scale related to the reduced 0–6‐km VWS. Interestingly, EPFs associated with TCs have the weakest convective intensity but the most active warm‐rain processes with the RSD being closer to the maritime regime.

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Section: Introductionmentioning

confidence: 99%

Subseasonal Variations of Convective and Microphysical Characteristics of Extreme Precipitation Over the Pearl River Delta at Monsoon Coast

Luo

et al. 2023

JGR Atmospheres

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“…The presummer heavy rainfall can be roughly classified into two types according to the dominant dynamic forcing origin: one closely associated with subtropical synoptic weather systems (hereafter, synoptic heavy rainfall ), for example, a cold or quasi‐stationary front, a low‐level vortex, and a shear line (Ding, 1994; Huang, 1986); and the other often occurring in the warm sector, a couple of hundred kilometers away from the subtropical weather systems (hereafter, warm‐sector heavy rainfall ) (Luo, 2017). The former type of heavy rainfall is often distributed extensively over inland south China, while the latter is located over coastal or inland south China with a smaller horizontal span but a larger accumulated amount (Luo et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Roles of Double Low‐Level Jets in the Generation of Coexisting Inland and Coastal Heavy Rainfall Over South China During the Presummer Rainy Season

et al. 2020

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In this study, the key dynamic factors influencing the formation of six heavy-rainfall events with coexisting inland and coastal rainfall over south China during May-June 2011-2017 are investigated using global ensemble forecasts from the European Centre for Medium-Range Weather Forecasts. An ensemble sensitivity analysis and comparisons between the identified good and bad members are conducted. Results confirm the importance of the synoptic low-level jet (SLLJ) and boundary layer jet (BLJ), but with different contributions, in determining the generation of the inland and coastal rainbelts, respectively. The inland heavy rainfall is closely related to both the SLLJ and BLJ, especially their meridional wind components. The more intense cold or quasi-stationary front, low-level vortex, or shear line accompanied by the stronger geostrophic southerly winds within both jets over inland and coastal south China is, the more rainfall over the inland region is favored. The ageostrophic southerly winds of the BLJ make limited contributions to the inland rainfall production but exert greater impacts on the generation of extreme (yet localized) coastal rainfall. The geostrophic meridional winds and associated low-level front/vortex also play a nonnegligible but indispensable role in producing the coastal rainfall. These findings add to our knowledge of heavy rainfall in the East Asian monsoon region.

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“…The most intense rainfall in the South China coasts usually appears in the warm sector, at least a couple of kilometers ahead of a front or without a front over South China [7][8][9][10][11][12]. Compared with the heavy precipitation caused by typhoons, the warm-sector heavy rainfall on the South China coast is more localized and occurs suddenly, making it an even greater challenge for operational forecasting [13].…”

Section: Introductionmentioning

confidence: 99%

Multiscale Perspectives on an Extreme Warm-Sector Rainfall Event over Coastal South China

Luo

et al. 2022

Remote Sensing

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On 22 June 2017, an extreme warm-sector rainfall event hit the western coastal area of South China, with maximum hourly and 12-h rainfall accumulations of 189.4 and 464.8 mm, respectively, which broke local historical records. Multisource observations were used to reveal multiscale processes contributing to the extreme rainfall. The results showed that a marine boundary layer jet (BLJ) coupled with a synoptic low-level jet (LLJ) inland played an important role in the formation of an extremely humid environment with a very low lifting condensation level of near-surface air. Under the favorable pre-convective conditions, convection was initialized at a mesoscale convergence line, aided by topographic lifting in the evening. During the nocturnal hours, the rainstorm developed and was maintained by a quasi-stationary mesoscale outflow boundary, which continuously lifted warm, moist air transported by the enhanced BLJ. When producing the extreme rainfall rates, the storm possessed relatively weak convection, with the 40 dBZ echo top hardly reaching 6 km. The extreme rainfall was produced mainly by the warm rain microphysical processes, mainly because the humid environment and the deep warm cloud layer facilitated the clouds’ condensational growth and collision–coalescence, and also reduced rain evaporation. As the storm evolved, the raindrop concentration increased rapidly from its initial stage and remained high until its weakening stage, but the mean raindrop size changed little. The extreme rain was characterized by the highest concentration of raindrops during the storm’s lifetime with a mean size of raindrops slightly larger than the maritime regime.

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Science and prediction of monsoon heavy rainfall

Cited by 14 publications

References 17 publications

Subseasonal Variations of Convective and Microphysical Characteristics of Extreme Precipitation Over the Pearl River Delta at Monsoon Coast

Subseasonal Variations of Convective and Microphysical Characteristics of Extreme Precipitation Over the Pearl River Delta at Monsoon Coast

Roles of Double Low‐Level Jets in the Generation of Coexisting Inland and Coastal Heavy Rainfall Over South China During the Presummer Rainy Season

Multiscale Perspectives on an Extreme Warm-Sector Rainfall Event over Coastal South China

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