Torrential rainfall responses to ice microphysical processes during pre-summer heavy rainfall over southern China

2012 ◽  
Vol 29 (3) ◽  
pp. 493-500 ◽  
Author(s):  
Xinyong Shen ◽  
Jia Liu ◽  
Xiaofan Li
Keyword(s):  
Heavy Rainfall ◽  
Southern China ◽  
Torrential Rainfall ◽  
Microphysical Processes

scholarly journals Heavy Rainfall Associated with Double Low-Level Jets over Southern China. Part II: Convection Initiation

2019 ◽  
Vol 147 (2) ◽  
pp. 543-565 ◽  
Author(s):  
Yu Du ◽  
Guixing Chen
Keyword(s):  
Heavy Rainfall ◽  
Mesoscale Model ◽  
Southern China ◽  
Northern South China Sea ◽  
Lower Troposphere ◽  
Small Scale ◽  
The South ◽  
Low Level ◽  
Low Level Jets ◽  
Convection Initiation

Abstract Heavy rainfall that occurred at the south coast of China on 10–11 May 2014 was associated with a synoptic-system-related low-level jet (SLLJ) and a boundary layer jet (BLJ). To clarify the role of the double low-level jets in convection initiation (CI), we perform convective-permitting simulations using a nonhydrostatic mesoscale model. The simulations reproduce the occurrence location and mesoscale evolution of new convective cells as well as their small-scale wavelike structures at the elevated layers, which are generally consistent with radar observations despite some differences in their orientation. The nighttime BLJ over the northern South China Sea strengthens the convergence at ~950 hPa near the coast where the BLJ’s northern terminus reaches the coastal terrain. Meanwhile, the SLLJ to the south of the inland cold front provides divergence at ~700 hPa near the SLLJ’s entrance region. Such low-level convergence and midlevel divergence collectively produce strong mesoscale lifting for CI at the coast. In addition to the enhanced mesoscale lifting, the double low-level jets also provide favorable conditions for the superimposed small-scale disturbances that can serve as effective moistening mechanisms of the lower troposphere during CI. In a sensitivity experiment with coastal terrain removed, CI still occurs near the coast but is delayed and weaker compared to the control run. This latter experiment suggests that double low-level jets and their coupling indeed exert key effects on CI, while the BLJ colliding with terrain may enhance coastal convergence for amplifying CI. These findings provide new insights into the occurrence of coastal heavy rainfall in the warm sector far ahead of the fronts.

scholarly journals Impact of 3DVAR Data Assimilation on the Prediction of Heavy Rainfall over Southern China

2013 ◽  
Vol 2013 ◽  
pp. 1-17 ◽  
Author(s):  
Tuanjie Hou ◽  
Fanyou Kong ◽  
Xunlai Chen ◽  
Hengchi Lei
Keyword(s):  
Data Assimilation ◽  
Heavy Rainfall ◽  
Positive Impact ◽  
Southern China ◽  
Precipitation Forecast ◽  
Radiosonde Data ◽  
Near Surface ◽  
Rainfall Events ◽  
Forecasting System ◽  
The Impact

This study examines the impact of three-dimensional variational data assimilation (3DVAR) on the prediction of two heavy rainfall events over Southern China by using a real-time storm-scale forecasting system. Initialized from the European Centre for Medium-Range Weather Forecasts (ECMWF) high-resolution data, the forecasting system is characterized by combining the Advanced Research Weather Research and Forecasting (WRF-ARW) model and the Advanced Regional Prediction System (ARPS) 3DVAR package. Observations from Doppler radars, surface Automatic Weather Station (AWS) network, and radiosondes are used in the experiments to evaluate the impact of data assimilation on short-term quantitative precipitation forecast (QPF) skill. Results suggest that extrasurface AWS data assimilation has slight but general positive impact on rainfall location forecasts. Surface AWS data also improve model results of near-surface variables. Radiosonde data assimilation improves the QPF skill by improving rainfall position accuracy and reducing rainfall overprediction. Compared with radar data, the overall impact of additional surface and radiosonde data is smaller and is reflected primarily in reducing rainfall overestimation. The assimilation of all radar, surface, and radiosonde data has a more positive impact on the forecast skill than the assimilation of either type of data only for the two rainfall events.

scholarly journals The Southern China Monsoon Rainfall Experiment (SCMREX)

2017 ◽  
Vol 98 (5) ◽  
pp. 999-1013 ◽  
Author(s):  
Yali Luo ◽  
Renhe Zhang ◽  
Qilin Wan ◽  
Bin Wang ◽  
Wai Kin Wong ◽  
...  
Keyword(s):  
Rainy Season ◽  
Heavy Rainfall ◽  
Monsoon Rainfall ◽  
Southern China ◽  
Precipitation Forecast ◽  
Ensemble Prediction ◽  
Rainfall Events ◽  
The World ◽  
Field Campaigns ◽  
Heavy Rainfall Events

Abstract During the presummer rainy season (April–June), southern China often experiences frequent occurrences of extreme rainfall, leading to severe flooding and inundations. To expedite the efforts in improving the quantitative precipitation forecast (QPF) of the presummer rainy season rainfall, the China Meteorological Administration (CMA) initiated a nationally coordinated research project, namely, the Southern China Monsoon Rainfall Experiment (SCMREX) that was endorsed by the World Meteorological Organization (WMO) as a research and development project (RDP) of the World Weather Research Programme (WWRP). The SCMREX RDP (2013–18) consists of four major components: field campaign, database management, studies on physical mechanisms of heavy rainfall events, and convection-permitting numerical experiments including impact of data assimilation, evaluation/improvement of model physics, and ensemble prediction. The pilot field campaigns were carried out from early May to mid-June of 2013–15. This paper: i) describes the scientific objectives, pilot field campaigns, and data sharing of SCMREX; ii) provides an overview of heavy rainfall events during the SCMREX-2014 intensive observing period; and iii) presents examples of preliminary research results and explains future research opportunities.

Observational Analysis of Heavy Rainfall Mechanisms Associated with Severe Tropical Storm Bilis (2006) after Its Landfall

2009 ◽  
Vol 137 (6) ◽  
pp. 1881-1897 ◽  
Author(s):  
Shuanzhu Gao ◽  
Zhiyong Meng ◽  
Fuqing Zhang ◽  
Lance F. Bosart
Keyword(s):  
Heavy Rainfall ◽  
Inner Core ◽  
Southern China ◽  
North Pacific Ocean ◽  
Mainland China ◽  
Vertical Wind Shear ◽  
Tropical Storm ◽  
Moist Convection ◽  
Second Stage ◽  
Deep Moist Convection

Abstract This observational study attempts to determine factors responsible for the distribution of precipitation over large areas of southern China induced by Bilis, a western North Pacific Ocean severe tropical storm that made landfall on the southeastern coast of mainland China on 14 July 2006 with a remnant circulation that persisted over land until after 17 July 2006. The heavy rainfalls associated with Bilis during and after its landfall can be divided into three stages. The first stage of the rainfall, which occurred in Fujian and Zhejiang Provinces, could be directly induced by the inner-core storm circulation during its landfall. The third stage of rainfall, which occurred along the coastal areas of Guangdong and Fujian Provinces, likely resulted from the interaction between Bilis and the South China Sea monsoon enhanced by topographical lifting along the coast. The second stage of the rainfall, which appeared inland around the border regions between Jiangxi, Hunan, and Guangdong Provinces, caused the most catastrophic flooding and is the primary focus of the current study. It is found that during the second stage of the rainfall all three ingredients of deep moist convection (moisture, instability, and lifting) are in place. Several mechanisms, including vertical wind shear, warm-air advection, frontogenesis, and topography, may have contributed simultaneously to the lifting necessary for the generation of the heavy rainfall at this stage.

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