Quasi-stationary extreme rain produced by mesoscale convective system on the Mei-Yu front

2020 ◽  
Vol 132 (5) ◽  
pp. 721-742
Author(s):  
Yuchun Zhao ◽  
Changhai Liu ◽  
Yehong Wang ◽  
Mitchell W. Moncrieff
Keyword(s):  
Mesoscale Convective System ◽  
Convective System ◽  
Mesoscale Convective ◽  
Extreme Rain

scholarly journals Identifikasi Fenomena Mesoscale Convective System (MCC) di Selat Karimata

2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Estri Diniyati ◽  
Yosafat Donni Haryanto
Keyword(s):  
Mesoscale Convective System ◽  
Equatorial Region ◽  
Extreme Weather Events ◽  
Convective System ◽  
Physical Conditions ◽  
Weather Events ◽  
Mesoscale Convective ◽  
Extreme Rain ◽  
Cloud Top Temperature ◽  
Cloud Core

Abstract—Indonesia located in the equatorial region which has potential to have a major impact on atmospheric physical conditions during extreme weather events such as the Mesoscale Convective Complex (MCC). MCC is a phenomenon that was first discovered by (Maddox, 1980) where this phenomenon is characterized by the presence of a quasi-circular (almost circular) cloud shield with an eccentricity of 0.7 with a cloud cover area of 100,000 km², the cloud core area covers 50,000 km² and cloud top temperature IR1 -52 ℃. These cloud conditions last for a minimum of 6 hours and cause severe weather and extreme rain. This study aims to identify the MCC phenomenon in the Karimata Strait on 19-20 September 2020 which caused heavy rains in parts of the West coast of Kalimantan and Bangka Island using Himawari-8 Satellite imagery data and the MATLAB application. The results showed that on September 19, MCC was identified at 09.00-19.00 UTC, then on September 20, MCC was identified at 16.00-23.00 UTC. At the time of the MCC event, Bangka and Pontianak regions experienced extreme rains recorded on AWS Digi Stamet Pontianak with rainfall reaching 43.4 mm/hour and ARG Lubuk Besar Bangka Tengah with rainfall reaching 16.8 mm/hour. Keywords: mesoscale convective complex (MCC), himawari-8, MATLAB Abstrak—Indonesia merupakan negara yang terletak diwilayah ekuator dimana berpotensi memiliki dampak besar terhadap kondisi fisik atmosfer saat terjadi cuaca ekstrem seperti Mesoscale Convective Complex (MCC). MCC merupakan fenomena yang pertama kali ditemukan oleh (Maddox, 1980) dimana fenomena ini dicirikan dengan adanya perisai awan yang berbentuk quasi circular (hampir lingkaran) dengan eksentrisitas ≥ 0,7 dengan luas area selimut awan ≥ 100.000 km² , luas area inti awan mencakup ≥ 50.000 km² serta suhu puncak awan IR1 ≤ -52 ℃. Kondisi awan tersebut bertahan minimun selama 6 jam dan menyebabkan cuaca buruk dan hujan ekstrem. Penelitian ini bertujuan untuk mengidentifikasi fenomena MCC di Selat Karimata pada Tanggal 19-20 September 2020 yang menyebabkan hujan lebat di sebagian wilayah Kalimantan bagian pesisir Barat dan Pulau Bangka menggunakan data citra Satelit Himawari-8 dan aplikasi MATLAB. Hasil penelitian menunjukkan pada tanggal 19 September, MCC teridentifikasi pada pukul 09.00-19.00 UTC selanjutnya tanggal 20 September 2020 MCC teridentifikasi pada pukul 16.00-23.00 UTC. Pada saat peristiwa MCC, wilayah Bangka dan Pontianak mengalami hujan ekstrem yang tercatat pada AWS Digi Stasiun Meteorologi Pontianak dengan curah hujan mencapai 43,4 mm/jam dan ARG Lubuk Besar Bangka Tengah dengan curah hujan mencapai 16,8 mm/jam. Kata kunci: mesoscale convective complex (MCC), himawari-8, MATLAB

Initiation and Organizational Modes of an Extreme-Rain-Producing Mesoscale Convective System along a Mei-Yu Front in East China

2014 ◽  
Vol 142 (1) ◽  
pp. 203-221 ◽  
Author(s):  
Yali Luo ◽  
Yu Gong ◽  
Da-Lin Zhang
Keyword(s):  
Spatial Scales ◽  
Mesoscale Convective System ◽  
Extreme Rainfall ◽  
Early Morning ◽  
East China ◽  
Convective System ◽  
Convective Initiation ◽  
Mesoscale Convective ◽  
Extreme Rain ◽  
Convective Cells

Abstract The initiation and organization of a quasi-linear extreme-rain-producing mesoscale convective system (MCS) along a mei-yu front in east China during the midnight-to-morning hours of 8 July 2007 are studied using high-resolution surface observations and radar reflectivity, and a 24-h convection-permitting simulation with the nested grid spacing of 1.11 km. Both the observations and the simulation reveal that the quasi-linear MCS forms through continuous convective initiation and organization into west–east-oriented rainbands with life spans of about 4–10 h, and their subsequent southeastward propagation. Results show that the early convective initiation at the western end of the MCS results from moist southwesterly monsoonal flows ascending cold domes left behind by convective activity that develops during the previous afternoon-to-evening hours, suggesting a possible linkage between the early morning and late afternoon peaks of the mei-yu rainfall. Two scales of convective organization are found during the MCS's development: one is the east- to northeastward “echo training” of convective cells along individual rainbands, and the other is the southeastward “band training” of the rainbands along the quasi-linear MCS. The two organizational modes are similar within the context of “training” of convective elements, but they differ in their spatial scales and movement directions. It is concluded that the repeated convective backbuilding and the subsequent echo training along the same path account for the extreme rainfall production in the present case, whereas the band training is responsible for the longevity of the rainbands and the formation of the quasi-linear MCS.

Equatorial Waves Triggering Extreme Rainfall and Floods in Southwest Sulawesi, Indonesia

2021 ◽  
Vol 149 (5) ◽  
pp. 1381-1401
Author(s):  
Beata Latos ◽  
Thierry Lefort ◽  
Maria K. Flatau ◽  
Piotr J. Flatau ◽  
Donaldi S. Permana ◽  
...  
Keyword(s):  
Mesoscale Convective System ◽  
Extreme Rainfall ◽  
Convective System ◽  
Rain Event ◽  
Equatorial Waves ◽  
Kelvin Wave ◽  
Atmospheric Variability ◽  
Low Level ◽  
Mesoscale Convective ◽  
Extreme Rain

AbstractOn the basis of detailed analysis of a case study and long-term climatology, it is shown that equatorial waves and their interactions serve as precursors for extreme rain and flood events in the central Maritime Continent region of southwest Sulawesi, Indonesia. Meteorological conditions on 22 January 2019 leading to heavy rainfall and devastating flooding in this area are studied. It is shown that a convectively coupled Kelvin wave (CCKW) and a convectively coupled equatorial Rossby wave (CCERW) embedded within the larger-scale envelope of the Madden–Julian oscillation (MJO) enhanced convective phase, contributed to the onset of a mesoscale convective system that developed over the Java Sea. Low-level convergence from the CCKW forced mesoscale convective organization and orographic ascent of moist air over the slopes of southwest Sulawesi. Climatological analysis shows that 92% of December–February floods and 76% of extreme rain events in this region were immediately preceded by positive low-level westerly wind anomalies. It is estimated that both CCKWs and CCERWs propagating over Sulawesi double the chance of floods and extreme rain event development, while the probability of such hazardous events occurring during their combined activity is 8 times greater than on a random day. While the MJO is a key component shaping tropical atmospheric variability, it is shown that its usefulness as a single factor for extreme weather-driven hazard prediction is limited.

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.

scholarly journals Evaluating Smartphone Pressure Observations for Mesoscale Analyses and Forecasts

2017 ◽  
Vol 32 (2) ◽  
pp. 511-531 ◽  
Author(s):  
Luke E. Madaus ◽  
Clifford F. Mass
Keyword(s):  
United States ◽  
Rural Areas ◽  
Mesoscale Convective System ◽  
Convective System ◽  
Active Period ◽  
Eastern United States ◽  
Short Term ◽  
Mesoscale Convective ◽  
Dynamic Structures ◽  
Further Development

Abstract Smartphone pressure observations have the potential to greatly increase surface observation density on convection-resolving scales. Currently available smartphone pressure observations are tested through assimilation in a mesoscale ensemble for a 3-day, convectively active period in the eastern United States. Both raw pressure (altimeter) observations and 1-h pressure (altimeter) tendency observations are considered. The available observation density closely follows population density, but observations are also available in rural areas. The smartphone observations are found to contain significant noise, which can limit their effectiveness. The assimilated smartphone observations contribute to small improvements in 1-h forecasts of surface pressure and 10-m wind, but produce larger errors in 2-m temperature forecasts. Short-term (0–4 h) precipitation forecasts are improved when smartphone pressure and pressure tendency observations are assimilated as compared with an ensemble that assimilates no observations. However, these improvements are limited to broad, mesoscale features with minimal skill provided at convective scales using the current smartphone observation density. A specific mesoscale convective system (MCS) is examined in detail, and smartphone pressure observations captured the expected dynamic structures associated with this feature. Possibilities for further development of smartphone observations are discussed.

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