An Extreme Rainfall Event in Coastal South China During SCMREX‐2014: Formation and Roles of Rainband and Echo Trainings

Liu, Lei; Luo, Yali; Guan, Zhaoyong; Zhang, Dalin

doi:10.1029/2018jd028418

Cited by 65 publications

(60 citation statements)

References 57 publications

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“…2). These statistics further supplement those of previous case studies that found existence of dual rain belts over coastal and inland SC during the pre-summer rainy season (Huang et al 1986;Ding 1994;Du and Chen 2018;Liu et al 2018). The presence and structure of LLJs are analyzed using ERA-interim data, largely following the methods adopted by Du et al (2014) to reveal their possible relation with the pre-summer rainfall over the SC coast.…”

Section: Analysis Of the Synoptic Conditionssupporting

confidence: 61%

Statistical Characteristics of Pre-summer Rainfall over South China and Associated Synoptic Conditions

Luo

et al. 2020

Journal of the Meteorological Society of Japan

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Climatological characteristics of pre-summer (April-to-June) rainfall over Southern China (SC) and associated synoptic conditions are examined using 1980-2017 hourly rainfall observations and reanalysis data. The rainfall amount, frequency, and intensity show pronounced regional variations and substantial changes between pre-and post-monsoon-onset periods. Owing to more favorable thermodynamic conditions after monsoon onset over South China Sea (SCS), rainfall intensifies generally over entire SC irrespective of the rainfall-event durations. Increased magnitudes of rainfall amount in longerduration (>6 h) events are found over a designated west-inland region (west of 111ºE), which are partially attributed to enhanced dynamic instability. In addition, rainfall events occur more frequently over the west-inland region, as well as coastal regions west side of 118ºE, but less over a designated east-inland region. The inland-region rainfall is closely linked to dynamic lifting driven by subtropical synoptic systems (low pressure and an associated front or shearline). The westward extension of the western North Pacific high and the eastward extension/movement of the front or shearline, interacting with the intra-period intensification of the southwesterly monsoonal flows, play important roles in providing high-θe (equivalent potential temperature) air to the west-and east-inland regions, respectively. The warm-sector, coastal rainfall is closely related to the deceleration of the southerly boundary layer (BL) jet (BLJ) over the northern SCS and associated convergence of BL high-θe air near the coast. Meanwhile the southwesterly synoptic-system-related low-level jet in the lowerto-middle troposphere to the south of the inland cold front can contribute to the coastal rainfall occurrence by providing divergence above the BL convergence near the coast. The BLJ often simultaneously strengthens with the lowertroposphere horizontal winds, suggesting a close association between the BLJ and the synoptic systems. The quantitative statistics provided in this study complement previous case studies or qualitative results and thus advance understanding about pre-summer rainfall over SC.

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Section: Analysis Of the Synoptic Conditionssupporting

confidence: 61%

Statistical Characteristics of Pre-summer Rainfall over South China and Associated Synoptic Conditions

Luo

et al. 2020

Journal of the Meteorological Society of Japan

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“…The impact of low-level warm and humid flow (e.g., Huang et al, 1986;Wang, Luo, et al, 2014), land-sea effects (e.g., Chen et al, 2014;Wu et al, 2017), terrain effects (e.g., Wu & Luo, 2016;Xu et al, 2012), and convective environmental conditions of mesoscale convective systems (MCSs; e.g., Xia et al, 2006;Zhang et al, 2011) have been emphasized. In recent years, using smaller spacing mesoscale observation data, several observation-based analyses have examined the structure, initiation, maintenance, and properties of warm-sector torrential rainfallassociated MCSs (e.g., Wang, Luo, et al, 2014;Wu & Luo, 2016;Liu et al, 2018). Planetary boundary layer (PBL) weather systems such as low-level jets, near-surface winds, and precipitation-generated cold outflows have been demonstrated to play important roles in initiating and maintaining warm-sector rainfall (Chen et al, 2017;Du & Chen, 2019;Wang, Luo, et al, 2014;Wu et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Practical and Intrinsic Predictability of a Warm‐Sector Torrential Rainfall Event in the South China Monsoon Region

Zhuang

Min

et al. 2020

JGR Atmospheres

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Warm‐sector torrential rainfall (WR) in the South China monsoon region has long been a forecasting challenge because of the limited capability of numerical models in heavy rainfall without strong synoptic forcing. Through convection‐allowing ensemble forecasts, this study explores both the intrinsic and practical predictability of a coastal WR event on 19–20 May 2015 during SCMREX (the Southern China Monsoon Rainfall Experiment). The results show a large variability in forecast performance among different members, indicating the practical limit of predictability. In general, GOOD members tend to have a stronger low‐level southerly wind over the sea (monsoon flow) and a considerable surface cooling over the northern mountains (associated with land/mountain breeze). Further investigation via ensemble‐based sensitivity analysis shows that the occurrence of WR is closely related to the nighttime strengthened (cooling) southerly wind (temperatures) over the sea (mountains), 1–3 hr prior to the convection initiation. In contrast, spatial scaling of the initial perturbations has little impact on the forecast after 3 hr and the meso‐γ‐scale rainfall is fully decorrelated after 12 hr, suggesting an intrinsic predictability limit for lead times as short as 6–12 hr. Sensitivity experiments are conducted with the initial‐condition differences reduced by almost an order of magnitude smaller than typical ensemble perturbations, with the results demonstrating that the rainstorm might be near the point of bifurcation, where predictability is intrinsically limited. The limits of both intrinsic and practical predictability highlight the need for rapidly updated and probabilistic convection‐allowing ensemble forecasts for events of this type.

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“…Organized mesoscale convective systems (MCSs) are regarded as a main contributor to heavy rainfall during the rainy season (Kuo & Chen, ; Luo et al, ; Zhang et al, ). Heavy rainfall and relevant MCSs during the presummer rainy season can be influenced by complicated multiscale atmospheric processes, including synoptic or subsynoptic weather systems (Huang et al, ; Kuo & Chen, ; Luo et al, ; Zhang et al, ; Zhang & Meng, ), local forcings such as terrain effects (Wang, Luo & Jou., ), land‐sea breezes (Chen et al, ; Chen et al, ), boundary layer winds or jets (Du & Chen, ), convectively generated cold pools (Liu et al, ; Wu & Luo, ), and urban heat islands (Wu et al, ).…”

Section: Introductionmentioning

confidence: 99%

Ensemble Sensitivity Analysis of Heavy Rainfall Associated With Three MCSs Coexisting Over Southern China

Shen

Chen

2020

JGR Atmospheres

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Using ensemble‐based sensitivity analysis, a heavy rainfall event over southern China was analyzed to investigate the key controlling factors of rainfall amount and relevant predictability. The heavy rainfall event was caused by three coexisting mesoscale convective systems (MCSs) over southwestern China (MCS‐A), the south coast of China (MCS‐B), and northern Taiwan (MCS‐C). The three MCSs exhibited differences and similarities with respect to their forecast accuracy and relevant key factors contributing to the rainfall centers, such as low‐level vortex/shear lines and low‐level jets. The strength and shape of the southwest vortex, a mesoscale vortex usually located over southwestern China with a horizontal scale of 200–600 km, exerted a significant effect on MCS‐A and MCS‐B, whereas the stronger shear line near the east coast of China was accompanied by increased precipitation in MCS‐C. In addition, the low‐level jets (LLJs) and their associated moisture transports had a strong influence on the three MCSs according to the LLJ location, strength, height, and direction. A synoptic LLJ located to the southeast of the southwest vortex with a stronger meridional (zonal) wind component and an axis more to the north (south) was related to increased precipitation in the corresponding region of MCS‐A (MCS‐B). In addition to the synoptic LLJ, the rainfall of MCS‐B was also influenced by a boundary layer jet over the ocean. Uncertainties in the aforementioned key factors might further influence the predictability of the three MCSs and thus lead to the differences in their forecast accuracy.

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An Extreme Rainfall Event in Coastal South China During SCMREX‐2014: Formation and Roles of Rainband and Echo Trainings

Cited by 65 publications

References 57 publications

Statistical Characteristics of Pre-summer Rainfall over South China and Associated Synoptic Conditions

Statistical Characteristics of Pre-summer Rainfall over South China and Associated Synoptic Conditions

Practical and Intrinsic Predictability of a Warm‐Sector Torrential Rainfall Event in the South China Monsoon Region

Ensemble Sensitivity Analysis of Heavy Rainfall Associated With Three MCSs Coexisting Over Southern China

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