scholarly journals A diagnostic study on the environmental influence of a mesoscale convective system over southern China in Meiyu season

2003 ◽  
Vol 84 (1-2) ◽  
pp. 33-55 ◽  
Author(s):  
G. T.-J. Chen ◽  
C.-C. Wang ◽  
C.-S. Hsieh
Keyword(s):  
Environmental Influence ◽  
Southern China ◽  
Mesoscale Convective System ◽  
Convective System ◽  
Diagnostic Study ◽  
Mesoscale Convective ◽  
Meiyu Season

Numerical simulation on mesoscale convective system along Mei-Yu front in Southern China

2000 ◽  
Vol 45 (22) ◽  
pp. 2093-2096 ◽  
Author(s):  
Qinghong Zhang ◽  
Kai-Hon Lau ◽  
Hongqing Wang ◽  
Shoujun Chen
Keyword(s):  
Numerical Simulation ◽  
Southern China ◽  
Mesoscale Convective System ◽  
Convective System ◽  
Mesoscale Convective

scholarly journals A Diagnostic Study of a Retreating Mei-Yu Front and the Accompanying Low-Level Jet Formation and Intensification

2006 ◽  
Vol 134 (3) ◽  
pp. 874-896 ◽  
Author(s):  
George Tai-Jen Chen ◽  
Chung-Chieh Wang ◽  
Li-Fen Lin
Keyword(s):  
Mesoscale Convective System ◽  
Heavy Rain ◽  
Meridional Wind ◽  
Convective System ◽  
Diagnostic Study ◽  
Cloud Band ◽  
Weather Forecasts ◽  
Low Level ◽  
Mesoscale Convective ◽  
Low Level Jet

Abstract During 7–8 June 1998, an organized mesoscale convective system (MCS) formed within the mei-yu frontal cloud band and moved northeastward to produce heavy rain over the island of Taiwan. During this period, the section of the mei-yu front east of Taiwan moved northward, most significantly for about 300 km over 12 h. Meanwhile, a low-level jet (LLJ) developed within the environmental southwesterly flow to the south of the mei-yu front and the MCS. Observations revealed that the front retreated as low-level meridional wind components over the postfrontal region shifted from northerly to southerly. Using European Centre for Medium-Range Weather Forecasts (ECMWF) analyses with piecewise potential vorticity (PV) inversion technique and other methods, a diagnostic study was carried out to investigate the northward frontal movement and the formation of the LLJ. Results indicated that diabatic latent heating from the MCS, large enough in scale, generated positive PV and height fall at low levels. The enhanced height gradient induced northwestward-directed ageostrophic winds and the LLJ formed southeast of the MCS through Coriolis torque. The southwesterly flow associated with this diabatic PV perturbation led to rapid retreat of the frontal segment east of Taiwan at a speed of about 25 m s−1, while the movement was dominated by horizontal advection in the present case. During this process of readjustment toward geostrophy, a thermally indirect circulation also appeared over and south of the front, and the LLJ formed within its lower branch at 850 hPa. The enhanced southwesterly winds reached LLJ strength because they were superimposed upon a background monsoon flow at the same direction. To the lee of Taiwan, the topography also played the role in enhancing local wind speed at lower levels and contributed toward the frontal retreat at nearby regions.

Ensemble Probabilistic Prediction of a Mesoscale Convective System and Associated Polarimetric Radar Variables Using Single-Moment and Double-Moment Microphysics Schemes and EnKF Radar Data Assimilation

2017 ◽  
Vol 145 (6) ◽  
pp. 2257-2279 ◽  
Author(s):  
Bryan J. Putnam ◽  
Ming Xue ◽  
Youngsun Jung ◽  
Nathan A. Snook ◽  
Guifu Zhang
Keyword(s):  
Mesoscale Convective System ◽  
Radar Data ◽  
Convective Precipitation ◽  
Convective System ◽  
Ensemble Forecasts ◽  
Verification Methods ◽  
Probabilistic Forecasts ◽  
Mesoscale Convective ◽  
Single Moment ◽  
Double Moment

Abstract Ensemble-based probabilistic forecasts are performed for a mesoscale convective system (MCS) that occurred over Oklahoma on 8–9 May 2007, initialized from ensemble Kalman filter analyses using multinetwork radar data and different microphysics schemes. Two experiments are conducted, using either a single-moment or double-moment microphysics scheme during the 1-h-long assimilation period and in subsequent 3-h ensemble forecasts. Qualitative and quantitative verifications are performed on the ensemble forecasts, including probabilistic skill scores. The predicted dual-polarization (dual-pol) radar variables and their probabilistic forecasts are also evaluated against available dual-pol radar observations, and discussed in relation to predicted microphysical states and structures. Evaluation of predicted reflectivity (Z) fields shows that the double-moment ensemble predicts the precipitation coverage of the leading convective line and stratiform precipitation regions of the MCS with higher probabilities throughout the forecast period compared to the single-moment ensemble. In terms of the simulated differential reflectivity (ZDR) and specific differential phase (KDP) fields, the double-moment ensemble compares more realistically to the observations and better distinguishes the stratiform and convective precipitation regions. The ZDR from individual ensemble members indicates better raindrop size sorting along the leading convective line in the double-moment ensemble. Various commonly used ensemble forecast verification methods are examined for the prediction of dual-pol variables. The results demonstrate the challenges associated with verifying predicted dual-pol fields that can vary significantly in value over small distances. Several microphysics biases are noted with the help of simulated dual-pol variables, such as substantial overprediction of KDP values in the single-moment ensemble.

scholarly journals Comprehensive Analysis of a Coast Thunderstorm That Produced a Sprite over the Bohai Sea

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 718
Author(s):  
Cong Pan ◽  
Jing Yang ◽  
Kun Liu ◽  
Yu Wang
Keyword(s):  
Bohai Sea ◽  
Mesoscale Convective System ◽  
Convective System ◽  
Return Stroke ◽  
Absolute Value ◽  
Transient Luminous Events ◽  
Stratiform Region ◽  
Before And After ◽  
Mesoscale Convective ◽  
Cloud To Ground Lightning

Sprites are transient luminous events (TLEs) that occur over thunderstorm clouds that represent the direct coupling relationship between the troposphere and the upper atmosphere. We report the evolution of a mesoscale convective system (MCS) that produced only one sprite event, and the characteristics of this thunderstorm and the related lightning activity are analyzed in detail. The results show that the parent flash of the sprite was positive cloud-to-ground lightning (+CG) with a single return stroke, which was located in the trailing stratiform region of the MCS with a radar reflectivity of 25 to 35 dBZ. The absolute value of the negative CG (−CG) peak current for half an hour before and after the occurrence of the sprite was less than 50 kA, which was not enough to produce the sprite. Sprites tend to be produced early in the maturity-to-dissipation stage of the MCS, with an increasing percentage of +CG to total CG (POP), indicating that the sprite production was the attenuation of the thunderstorm and the area of the stratiform region.

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