scholarly journals Environment and Processes for Heavy Rainfall in the Early Morning over the Korean Peninsula during Episodes of Cloud Clusters Associated with Mesoscale Troughs

2019 ◽  
Vol 97 (3) ◽  
pp. 633-655 ◽  
Author(s):  
Uju SHIN ◽  
Tae-Young LEE ◽  
Sang-Hun PARK
Keyword(s):  
Korean Peninsula ◽  
Heavy Rainfall ◽  
Early Morning ◽  
Cloud Clusters

scholarly journals An Observational Study of Mesoscale Convective Systems with Heavy Rainfall over the Korean Peninsula

2006 ◽  
Vol 21 (2) ◽  
pp. 125-148 ◽  
Author(s):  
Hyung Woo Kim ◽  
Dong Kyou Lee
Keyword(s):  
Observational Study ◽  
Korean Peninsula ◽  
Wind Shear ◽  
Heavy Rainfall ◽  
Vertical Wind Shear ◽  
Vertical Wind ◽  
Mesoscale Convective Systems ◽  
Low Level ◽  
Convective Systems ◽  
Mesoscale Convective

Abstract A heavy rainfall event induced by mesoscale convective systems (MCSs) occurred over the middle Korean Peninsula from 25 to 27 July 1996. This heavy rainfall caused a large loss of life and property damage as a result of flash floods and landslides. An observational study was conducted using Weather Surveillance Radar-1988 Doppler (WSR-88D) data from 0930 UTC 26 July to 0303 UTC 27 July 1996. Dominant synoptic features in this case had many similarities to those in previous studies, such as the presence of a quasi-stationary frontal system, a weak upper-level trough, sufficient moisture transportation by a low-level jet from a tropical storm landfall, strong potential and convective instability, and strong vertical wind shear. The thermodynamic characteristics and wind shear presented favorable conditions for a heavy rainfall occurrence. The early convective cells in the MCSs initiated over the coastal area, facilitated by the mesoscale boundaries of the land–sea contrast, rain–no rain regions, saturated–unsaturated soils, and steep horizontal pressure and thermal gradients. Two MCSs passed through the heavy rainfall regions during the investigation period. The first MCS initiated at 1000 UTC 26 July and had the characteristics of a supercell storm with small amounts of precipitation, the appearance of a mesocyclone with tilting storm, a rear-inflow jet at the midlevel of the storm, and fast forward propagation. The second MCS initiated over the upstream area of the first MCS at 1800 UTC 26 July and had the characteristics of a multicell storm, such as a broken areal-type squall line, slow or quasi-stationary backward propagation, heavy rainfall in a concentrated area due to the merging of the convective storms, and a stagnated cluster system. These systems merged and stagnated because their movement was blocked by the Taebaek Mountain Range, and they continued to develop because of the vertical wind shear resulting from a low-level easterly inflow.

scholarly journals Evaluation of Rainfall Forecasts with Heavy Rain Types in the High-Resolution Unified Model over South Korea

2019 ◽  
Vol 34 (5) ◽  
pp. 1277-1293 ◽  
Author(s):  
Hwan-Jin Song ◽  
Byunghwan Lim ◽  
Sangwon Joo
Keyword(s):  
High Resolution ◽  
South Korea ◽  
Korean Peninsula ◽  
Heavy Rainfall ◽  
Rainfall Intensity ◽  
Heavy Rain ◽  
Unified Model ◽  
Moderate Intensity ◽  
Local Data ◽  
Total Rainfall

Abstract Heavy rainfall events account for most socioeconomic damages caused by natural disasters in South Korea. However, the microphysical understanding of heavy rain is still lacking, leading to uncertainties in quantitative rainfall prediction. This study is aimed at evaluating rainfall forecasts in the Local Data Assimilation and Prediction System (LDAPS), a high-resolution configuration of the Unified Model over the Korean Peninsula. The rainfall of LDAPS forecasts was evaluated with observations based on two types of heavy rain events classified from K-means clustering for the relationship between surface rainfall intensity and cloud-top height. LDAPS forecasts were characterized by more heavy rain cases with high cloud-top heights (cold-type heavy rain) in contrast to observations showing frequent moderate-intensity rain systems with relatively lower cloud-top heights (warm-type heavy rain) over South Korea. The observed cold-type and warm-type events accounted for 32.7% and 67.3% of total rainfall, whereas LDAPS forecasts accounted for 65.3% and 34.7%, respectively. This indicates severe overestimation and underestimation of total rainfall for the cold-type and warm-type forecast events, respectively. The overestimation of cold-type heavy rainfall was mainly due to its frequent occurrence, whereas the underestimation of warm-type heavy rainfall was affected by both its low occurrence and weak intensity. The rainfall forecast skill for the warm-type events was much lower than for the cold-type events, due to the lower rainfall intensity and smaller rain area of the warm-type. Therefore, cloud parameterizations for warm-type heavy rain should be improved to enhance rainfall forecasts over the Korean Peninsula.

Predictability for Heavy Rainfall over the Korean Peninsula during the Summer using TIGGE Model

Atmosphere ◽  
2012 ◽  
Vol 22 (3) ◽  
pp. 287-298 ◽  
Author(s):  
Yoon-Jeong Hwang ◽  
Yeon-Hee Kim ◽  
Kwan-Young Chung ◽  
Dong-Eon Chang
Keyword(s):  
Korean Peninsula ◽  
Heavy Rainfall

scholarly journals The scale of typhoon RUSA

2006 ◽  
Vol 3 (5) ◽  
pp. 3147-3182 ◽  
Author(s):  
N. W. Kim ◽  
Y. S. Won ◽  
I. M. Chung
Keyword(s):  
Return Period ◽  
Korean Peninsula ◽  
Heavy Rainfall ◽  
Hydraulic Structure ◽  
Hydrological Variable ◽  
Areal Rainfall ◽  
Qualitative Analyses ◽  
Extensive Damage

Abstract. In August 2002, Typhoon RUSA hit Korea with severe gale and storm, causing extensive damage throughout the whole country and especially in the Gangneung area. Even on a single day, Typhoon RUSA recorded up to 879.5 mm of rainfall in the Gangneung area. Quantitative and qualitative analyses of the scale of Typhoon RUSA are performed in this study. Most of the inland affected by RUSA in the Korean Peninsula recorded heavy rainfall, equivalent to a return period of more than 200 years. Especially, rainfall of 24 h duration exceeded the maxima observed so far. Although areal rainfall showed a rapidly decreasing trend with increasing area, it reached 96 percent of the existing PMP within a 2000 km2 area and recorded the maximum observed value of Korea according to a DAD analysis of rainfall. Re-estimated PMP values obtained from a hydro-meteorological approach compared with existing PMP estimates revealed a discrepancy between the two values, which showed that re-estimated PMP values of 12 to 24 h duration within 2000 km2 exceeded the existing PMP estimates of Korea. Therefore, modification of the existing PMP is required, which is used as a design hydrological variable of hydraulic structure.

The Crucial Role of Synoptic Pattern in Determining the Spatial Distribution and Diurnal Cycle of Heavy Rainfall over the South China Coast

2020 ◽  
pp. 1-47
Author(s):  
Chenli Wang ◽  
Kun Zhao ◽  
Anning Huang ◽  
Xingchao Chen ◽  
Xiaona Rao
Keyword(s):  
South China ◽  
Heavy Rainfall ◽  
Warm Season ◽  
Early Morning ◽  
The South ◽  
Synoptic Patterns ◽  
Low Level ◽  
South China Coast ◽  
China Coast

AbstractSouth China coast suffers frequent heavy rainfall every warm-season. Based on the objective classification method of principle components analysis, the key role of synoptic pattern in determining the heavy rainfall processes occurred over the South China coast in warm season during 2008-2018 is examined in this study. We found heavy rainfall occurs most frequently under three typical synoptic patterns (P1-P3 hereafter) characterized by strong low-level onshore winds. P1 and P3 are featured by a prevailing southwesterly monsoonal flow in the lower troposphere, with heavy rainfall frequently occurring over the inland windward region in the afternoon associated with the orographic lifting and solar heating. The onshore wind of P3 is stronger than P1 as the western Pacific subtropical high extends more westward to 122°E, which induces stronger low-level convergence along the coastline than P1 when the ageostrophic wind veers from offshore to onshore direction in the early morning. Hence, a secondary early morning rainfall peak can be found along the coastline. P2 is characterized by a low-level vortex located over the southwest of south China. Heavy rainfall under P2 usually initiate over the western part of the coastal region in the morning and then propagate towards inland in the afternoon. Overall, the synoptic patterns strongly determine the spatial distribution and diurnal cycle of heavy rainfall over the South China coast. It is closely related to the diurnally varying low-level onshore winds rather than the low-level jets, as well as the different interactions between the low-level onshore winds and the local orography, coastline and land-sea breeze circulations under different synoptic patterns.

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