scholarly journals Simulation of Severe Local Storm by Mesoscale Model MM5 and Validation Using Data from Different Platforms

2015 ◽  
Vol 2015 ◽  
pp. 1-23 ◽  
Author(s):  
Prosenjit Chatterjee ◽  
Utpal Kumar De ◽  
Devendra Pradhan
Keyword(s):  
Heavy Rainfall ◽  
West Bengal ◽  
Mesoscale Model ◽  
Temperature Drop ◽  
Pressure Rise ◽  
Convective Cloud ◽  
Rainfall Simulation ◽  
Temporal Shift ◽  
Rainfall Occurrence ◽  
Using Data

During premonsoon season (March to May) convective developments in various forms are common phenomena over the Gangetic West Bengal, India. In the present work, simulation of wind squall on three different dates has been attempted with the help of mesoscale model MM5. The combination of various physical schemes in MM5 is taken as that found in a previous work done to simulate severe local storms over the Gangetic West Bengal. In the present study the model successfully simulates wind squall showing pressure rise, wind shift, wind surge, temperature drop, and heavy rainfall, in all cases. Convective cloud development and rainfall simulation by the model has been validated by the corresponding product from Doppler Weather Radar located at Kolkata and TRMM satellite product 3B42 (V6), respectively. It is found that the model is capable of capturing heavy rainfall pattern with up to three-hour time gap existing between simulation and observation of peak rainfall occurrence. In all simulations there is spatial as well as temporal shift from observation.

scholarly journals Role of land state in a high resolution mesoscale model for simulating the Uttarakhand heavy rainfall event over India

2016 ◽  
Vol 125 (3) ◽  
pp. 475-498 ◽  
Author(s):  
P V Rajesh ◽  
S Pattnaik ◽  
D Rai ◽  
K K Osuri ◽  
U C Mohanty ◽  
...  
Keyword(s):  
High Resolution ◽  
Heavy Rainfall ◽  
Mesoscale Model ◽  
Rainfall Event ◽  
Heavy Rainfall Event

scholarly journals Initiation and Maintenance Mechanisms for Heavy Precipitation System over a Mountainous Island under a Prevailing Monsoon Current

2016 ◽  
Vol 5 (2) ◽  
pp. 90
Author(s):  
Y.-L. Lin ◽  
K.-Y. Lee ◽  
C.-S. Chen ◽  
F.-Y. Cheng ◽  
P.-L. Lin ◽  
...  
Keyword(s):  
Heavy Rainfall ◽  
Mesoscale Model ◽  
Convective Available Potential Energy ◽  
Leading Edge ◽  
Western Slope ◽  
Mountain Range ◽  
Unstable Flow ◽  
Near Surface ◽  
Precipitation System ◽  
Early Afternoon

In this study, the initiation and maintenance mechanisms of two long-lived, summer heavy rainfall systems over Taiwan are investigated by performing observational data analyses and numerical simulations using a mesoscale model. For both cases of 9-10 July 2008 (Case A) and 18-19 August 2006 (Case B), the heavy rainfall system developed over the western slope of the Central Mountain Range (CMR) under low-level prevailing southwesterly and westerly flows in early afternoon, respectively. These heavy rainfall systems were moving westward toward Taiwan Strait from CMR, while the embedded individual cells were moving in the opposite direction, behaving like a multicell storm. It was also found these individual cells were initiated, enhanced, and then maintained at the leading edge of the near-surface cool outflow and merged with the heavy rainfall systems which became long-lived. These heavy rainfall systems were classified as an upstream propagating precipitation system in a low Froude-number, conditionally unstable flow with high convective available potential energy (CAPE) or Regime I as proposed in a previous study.

scholarly journals Cause Analysis on Eastward Movement of Southwest China Vortex and Its Induced Heavy Rainfall in South China

2015 ◽  
Vol 2015 ◽  
pp. 1-22 ◽  
Author(s):  
Yongren Chen ◽  
Yueqing Li ◽  
Tianliang Zhao
Keyword(s):  
South China ◽  
Heavy Rainfall ◽  
Southwest China ◽  
Dominant Role ◽  
Vertical Wind Shear ◽  
Heavy Rain ◽  
Convective Systems ◽  
Rainfall Occurrence ◽  
Positive Vorticity ◽  
Upper Level Jet

The movement of southwest China vortex (SWV) and its heavy rainfall process in South China had been investigated during June 11–14, 2008. The results show that under the steering of upper-level jet (ULJ) and mid-level westerly trough, SWV moved eastward from southern Sichuan Plateau, across eastern Yunnan-Guizhou Plateau to South China, forming an obvious heavy rain belt. SWV developed in the large storm-relative helicity (SRH) environment, as environmental wind field continuously transferred positive vorticity to it to support its development. The thermodynamic structures of distinctive warm (cold) advections in front (rear) of the SWV movement are also important factors for the SWV evolutions with a southwest low-level jet (LLJ) and vertical wind shear. SWV development was associated with the distributions of negative MPV1 (the barotropic item of moist potential vorticity) and positive MPV2 (the baroclinic item of it). The MPV1 and MPV2 played the dominant role in the formation and the evolution of SWV, respectively. The mesoscale convective systems (MCSs) frequently occurred and persisted in water vapor convergence areas causing the severe heavy rainfall. The areas of high moist helicity divergence and heavy rainfall are consistent, and the moist helicity divergence could be a good indicator for heavy rainfall occurrence.

North Sea Wave Analysis Using Data Assimilation and Mesoscale Model Forcing Winds

2018 ◽  
Vol 144 (4) ◽  
pp. 04018005 ◽  
Author(s):  
S. Caires ◽  
G. J. Marseille ◽  
M. Verlaan ◽  
A. Stoffelen
Keyword(s):  
Data Assimilation ◽  
North Sea ◽  
Mesoscale Model ◽  
Wave Analysis ◽  
Using Data ◽  
Sea Wave

Numerical Simulations of Convective Cloud Merging Processes at Different Development Stages

2020 ◽  
Author(s):  
Jing Zhai ◽  
Yong Huang
Keyword(s):  
Mesoscale Model ◽  
Convective Cloud ◽  
Cloud Water ◽  
The Other ◽  
Small Cells ◽  
Horizontal Scale ◽  
Development Stages ◽  
Ice Surface ◽  
Radar Echo ◽  
Simulation Results

<p>Mergers of cells in a severe convective weather on 22 July 2008 are simulated and analyzed by Mesoscale Model 5 (referred to as MM5）and radar network data. Observation results show that, the horizontal scale of the echo above 30 dBZ, which represent the small cells, is about 10 km, and the small cells that the echo centers are 20km apart merge into a larger cell at dozens of km of horizontal scale.. Mergers begin from the peripheral radar echo, and then strong central radar echo merges at the low level, at last, the acreage of strong radar echo increases after the merger. The contrast between the observations and the simulation results shows that they are consistent. Analysis on the simulation results of two kinds of cell mergers at different development stages based on the third network model output shows that, while the cell pairs are with almost the same intensity, cells would develop after merger; while one of the cell pairs is in stronger development however the other one weaker, the stronger cell would keep on development and the weaker cell would die out. During the merger, a new cloud water center appears in the low convergence region between the cell pairs, and would replace the two cloud water centers of the former cells, or the new cloud water center would merger with one of the old cloud water centers while the other old cloud water center disappears. The analysis of the simulation results also shows that, the cell merger would lead to the cloud top lifting and the increase in the radar echo, content of cloud water and ice, surface rainfall.</p>

Mesoscale Surface Pressure and Temperature Features Associated with Bow Echoes

2010 ◽  
Vol 138 (1) ◽  
pp. 212-227 ◽  
Author(s):  
Rebecca D. Adams-Selin ◽  
Richard H. Johnson
Keyword(s):  
Gravity Wave ◽  
Surface Pressure ◽  
Temperature Drop ◽  
Gravity Current ◽  
Pressure Rise ◽  
Surface Pattern ◽  
Cold Pool ◽  
Surface Features ◽  
Oklahoma Mesonet ◽  
Reflectivity Data

Abstract This study examines observed mesoscale surface pressure, temperature, and wind features of bow echoes. Bow-echo events in the area of the Oklahoma Mesonet are selected for study to take advantage of high-resolution surface data. Thirty-six cases are identified using 2-km-resolution radar reflectivity data over a 4-yr period (2002–05); their surface features are interrogated using the mesonet data. Distinct surface features usually associated with squall lines, the mesohigh and cold pool, are found to also accompany bow echoes. A common surface pattern preceding bowing is identified. Prior to new bowing development, the mesohigh surges ahead of the convective line while the cold pool remains centered behind it. Surface winds shift to a ground-relative outflow pattern upon arrival of the mesohigh surge. Approximately 30 min later, a new bowing segment forms with its apex slightly to the left (with respect to the direction of system motion) of the mesohigh surge. The cold pool follows the convective line as it bows. This process is termed the “pressure surge–new bowing” cycle, and a conceptual model is presented. In one representative case, the surface signature of a gravity wave, identified through spatial and temporal filtering, is tracked. It is presumed to be generated by deep heating within the convective line. The wave moved at nearly 35 m s−1 and has heretofore been undetected in mesoanalysis studies. Two other distinct features, a sharp pressure rise and temperature drop, were also observed at all mesonet stations affected by the system. Possible explanations for these features in terms of a gravity current, gravity wave, or atmospheric bore are explored.

scholarly journals Impact of radar data assimilation for the simulation of a heavy rainfall case in central Italy using WRF–3DVAR

2014 ◽  
Vol 7 (9) ◽  
pp. 2919-2935 ◽  
Author(s):  
I. Maiello ◽  
R. Ferretti ◽  
S. Gentile ◽  
M. Montopoli ◽  
E. Picciotti ◽  
...  
Keyword(s):  
Heavy Rainfall ◽  
Mesoscale Model ◽  
Initial Conditions ◽  
Positive Impact ◽  
Central Italy ◽  
Wrf Model ◽  
Forecast Accuracy ◽  
Radar Data ◽  
Heavy Rainfall Event ◽  
Dwr Data

Abstract. The aim of this study is to investigate the role of the assimilation of Doppler weather radar (DWR) data in a mesoscale model for the forecast of a heavy rainfall event that occurred in Italy in the urban area of Rome from 19 to 22 May 2008. For this purpose, radar reflectivity and radial velocity acquired from Monte Midia Doppler radar are assimilated into the Weather Research Forecasting (WRF) model, version 3.4.1. The general goal is to improve the quantitative precipitation forecasts (QPF): with this aim, several experiments are performed using the three-dimensional variational (3DVAR) technique. Moreover, sensitivity tests to outer loops are performed to include non-linearity in the observation operators. In order to identify the best initial conditions (ICs), statistical indicators such as forecast accuracy, frequency bias, false alarm rate and equitable threat score for the accumulated precipitation are used. The results show that the assimilation of DWR data has a large impact on both the position of convective cells and on the rainfall forecast of the analyzed event. A positive impact is also found if they are ingested together with conventional observations. Sensitivity to the use of two or three outer loops is also found if DWR data are assimilated together with conventional data.

scholarly journals Exceptional heavy rainfall over Ajoy, Mayurakshi and Kansabati catchments and QPF verification during flood season of September 2009

MAUSAM ◽  
2022 ◽  
Vol 63 (3) ◽  
pp. 479-488
Author(s):  
SOUMENDU SENGUPTA ◽  
B.K. MANDAL ◽  
D. PRADHAN
Keyword(s):  
Heavy Rainfall ◽  
West Bengal ◽  
Precipitation Forecast ◽  
Flood Season ◽  
Quantitative Precipitation Forecast ◽  
Damodar Valley ◽  
Average Precipitation ◽  
Synoptic Features ◽  
River Catchments

Ajoy, Mayurakshi, Kansabati are three important river catchments of West Bengal and Jharkhand state, received very heavy rainfall during two consecutive days of flood season in the month of September 2009. The contribution of heavy rainfall & combined discharges from Damodar Valley Corporation (DVC) reservoirs during the period of heavy rainspells over these catchments enhanced flood situation in some districts of West Bengal. The synoptic features based on weather charts, cloud imageries of satellite and radar pictures have been taken to analyse. The realized areal average precipitation (AAP) as per rainfall recorded at 0300 UTC of next day have also been taken to verify the quantitative precipitation forecast (QPF) of 6&7 September 2009.

scholarly journals PERBAIKAN ESTIMASI CURAH HUJAN BERBASIS DATA SATELIT DENGAN MEMPERHITUNGKAN FAKTOR PERTUMBUHAN AWAN

2020 ◽  
Vol 20 (2) ◽  
pp. 67-78
Author(s):  
Adi Mulsandi ◽  
Mamenun Mamenun ◽  
Lutfi Fitriano ◽  
Rahmat Hidayat
Keyword(s):  
Growth Factor ◽  
Satellite Data ◽  
Point Cloud ◽  
Heavy Rainfall ◽  
Convective Cloud ◽  
Cloud System ◽  
Slope Parameter ◽  
Rainfall Estimation ◽  
Coupled Method ◽  
Stratiform Clouds

Intisari Permasalahan utama dalam mengestimasi curah hujan menggunakan data satelit adalah kegagalan membedakan antara awan cumuliform dengan awan stratiform dimana dapat menyebabkan nilai estimasi hujan under/overestimate. Dalam penelitian ini teknik estimasi curah hujan berbasis satelit yang digunakan adalah modifikasi Convective Stratiform Technique (CSTm). CSTm memiliki kelemahan ketika harus menghitung sistem awan konveksi dengan inti konveksi yang sangat luas karena akan memiliki nilai slope parameter kecil, sehingga menghasilkan estimasi curah hujan yang underestimate. Dengan melibatkan perhitungan faktor pertumbuhan awan di algoritma CSTm permasalahan tersebut dapat diatasi. Penelitian ini menerapkan algoritma CSTm dan faktor pertumbuhan awan (CSTm+Growth Factor) untuk mengestimasi kejadian hujan lebat yang menyebabkan banjir di Jakarta pada tanggal 24 Januari 2016 yang digunakan juga sebagai studi kasus di proyek pengembangan model NWP di BMKG. Hasil penelitian menunjukan bahwa perlibatan faktor pertumbuhan awan sangat efektif memperbaiki kelemahan teknik CSTm, diperlihatkan dengan peningkatan nilai korelasi dari 0.6 menjadi 0.8 untuk wilayah Kemayoran dan -0.1 menjadi 0.83 untuk wilayah Cengkareng. Secara umum gabungan teknik CSTm dan faktor pertumbuhan awan dapat memperbaiki estimasi nilai intensitas dan fase hujan. Abstract  The main problem in estimating rainfall using satellite data is a failure to distinguish between cumuliform and stratiform clouds, which can cause under/overestimate of rains. In this research, the Modified Convective Stratiform Technique (CSTm) has been used to estimate rainfall based on satellite data. The weakness of the CSTm technique is defined when calculating the convective cloud system within a widely convective point. Cloud convective will have a low value of parameter slope and produce an underestimate of rainfall. This issue can be resolved by calculating the cloud growth factor on CSTm. CSTm algorithm and cloud growth factor (CSTm+Growth Factor) has been applied to this research to estimate heavy rainfall for floods event in Jakarta area on January 24th, 2016. The result showed that the cloud growth factor is very effective in improving the weakness of rainfall estimation using the CSTm technique. Correlation between estimation and observation rainfall has increased from 0,6 to 0,8 on Kemayoran and from -0,1 to 0,83 on Cengkareng. The coupled method of CSTm and cloud growth factor significantly improve in estimating phase and intensity of rainfall.

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