scholarly journals Large Scale Processes for Understanding Extreme Rain Storm Over Rangamati on 12 June 2017- A Case Study

2020 ◽  
Vol 11 (2) ◽  
pp. 87-97
Author(s):  
Samarendra Karmakar ◽  
Mohan Kumar Das ◽  
Haripada Sarker
Keyword(s):  
Bay Of Bengal ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Early Period ◽  
Analysis Data ◽  
Southwest Monsoon ◽  
Monsoon Depression ◽  
Heavy Rainfall Event ◽  
Strong Wind ◽  
Synoptic Conditions

Attempts have been made to study the large-scale surface and upper air synoptic processes associated with a monsoon depression during 11-12 June 2017. In this study, Grid Analysis and Display System (GrADS) software has been used to prepare the large-scale sea level pressure and upper flow patterns by analyzing the FNL re-analysis data. In this analysis, FNL dataset is used to characterize the rainstorms, with key hydrometeorological variables describing the prior conditions of the very heavy rainfall event presented the study. National Center for Environmental Prediction (NCEP) Final (FNL) analysis data of 1o by 1o grids for every 6 hours are used for large scale synoptic analysis. The disastrous event was a strong monsoon depression in the early period of southwest monsoon 2017. Due to this depression, very heavy rainfall occurred in the southeastern Bangladesh. Rangamati recorded 343 mm of rainfall in the 24 hours on 12 June 2017. Massive landslides occurred in three districts such as Rangamati, Bandarban and Chittagong. The analysis of surface and upper air synoptic conditions has revealed that a well-marked low was formed over the northwest Bay of Bengal within the low-pressure belt passing from Somalia coast extending through southern Pakistan, and India up to east central Bay of Bengal and adjoining Bangladesh. The wind speed is calculated from the pressure distribution and is found to be 24.23ms-1, which is at par with the observed one. The well-marked low was subsequently intensified into a depression and moved northeastwards over Bangladesh. Strong southsouthwesterly winds were associated in the eastern side of the depression, especially over Chittagong Hill Tracts. The depression was found to extend up to 500 hPa level as seen from the distribution of geopotential and strong circulation around the centre. Winds were advecting from large continental and Ocean areas over the South Asia. Strong winds and moisture influx, strong narrow coma-like trough from a micro low at the surface to 500 hPa level as well as strong wind shear were responsible for the heavy rainfall, disastrous effects and massive landslides over Rangamati and adjoining areas. Journal of Engineering Science 11(2), 2020, 87-97

Simulation of a heavy rainfall event during southwest monsoon using high-resolution NCUM-modeling system: a case study

2018 ◽  
Vol 131 (4) ◽  
pp. 1035-1054 ◽  
Author(s):  
Devajyoti Dutta ◽  
A. Routray ◽  
D. Preveen Kumar ◽  
John P. George ◽  
Vivek Singh
Keyword(s):  
High Resolution ◽  
Heavy Rainfall ◽  
Southwest Monsoon ◽  
Rainfall Event ◽  
Heavy Rainfall Event ◽  
System A

scholarly journals A Study of Two Propagating Heavy-Rainfall Episodes near Taiwan during SoWMEX/TiMREX IOP-8 in June 2008. Part II: Sensitivity Tests on the Roles of Synoptic Conditions and Topographic Effects

2014 ◽  
Vol 142 (8) ◽  
pp. 2644-2664 ◽  
Author(s):  
Chung-Chieh Wang ◽  
Jason Chieh-Sheng Hsu ◽  
George Tai-Jen Chen ◽  
Dong-In Lee
Keyword(s):  
Heavy Rainfall ◽  
Warm Season ◽  
Southwest Monsoon ◽  
First Episode ◽  
Topographic Effects ◽  
Terrain Effects ◽  
Sensitivity Tests ◽  
Synoptic Conditions ◽  
Synoptic Forcing ◽  
Central United States

Abstract This study is the second of a two-part series to investigate two rainfall episodes in the Hovmöller space near Taiwan during the eighth intensive observing period (IOP-8, 12–17 June 2008) of the Southwest Monsoon Experiment/Terrain-influenced Monsoon Rainfall Experiment (SoWMEX/TiMREX). The first episode moved eastward and the second westward, and both caused heavy rainfall in Taiwan. The goal of Part I was to better understand the mechanism and controlling factors for the organization and propagation of the episodes. Here in Part II, the detailed roles played by synoptic conditions and terrain effects are further examined. Three sensitivity tests (at 2.5-km grid spacing) are designed to include only the effects of synoptic evolution (SNP), and those from land–sea distribution–diurnal variations on top of a mean background with/without topography (DIU/DNT). As the benchmark, the control (CTL) experiment captures the 6-day event successfully and is validated in Part I. In SNP, the two episodes are reproduced with overall similarity to CTL and the observation, and this confirms that the general location/time of rainfall are mainly controlled by synoptic forcing in this case, in contrast to typical warm-season conditions in the central United States. Even so, diurnal effects can still exert discernible impacts and modulate local convective development in many instances, particularly an afternoon enhancement over terrain, and the averaged diurnal cycle in CTL over southeastern China resembles those in DIU/DNT rather than that in SNP (with no land). The steep topography of Taiwan is especially important for its rainfall distribution, including the heavy rainfall on 16 June through processes as postulated by Xu et al.

scholarly journals The Impact of Tropical Storm Paul (1999) on the Motion and Rainfall Associated with Tropical Storm Rachel (1999) near Taiwan

2010 ◽  
Vol 138 (5) ◽  
pp. 1635-1650 ◽  
Author(s):  
Chun-Chieh Wu ◽  
Kevin K. W. Cheung ◽  
Jan-Huey Chen ◽  
Cheng-Chuan Chang
Keyword(s):  
Conceptual Model ◽  
South China ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Monsoon Trough ◽  
Tropical Storm ◽  
Heavy Rainfall Event ◽  
Key Factors ◽  
Southern Taiwan ◽  
The Impact

Abstract A heavy rainfall event associated with the passage of Tropical Storm Rachel (1999) over southern Taiwan was studied in which a conceptual model was proposed. In the model, Tropical Storm Paul (1999) plays an important role in impeding the movement of Rachel, thus becoming one of the key factors in enhancing the rainfall amount in southern Taiwan. To further quantify the above concept, a mesoscale numerical model is used to evaluate the influence of Paul on the simulated rainfall associated with Rachel near Taiwan. Sensitivity experiments are performed by removing the circulation of Paul, and/or the large-scale monsoon trough system, where Paul is imbedded. The potential vorticity diagnosis shows that the movement of Rachel is indeed affected by the presence of Paul. Nevertheless, a more detailed analysis shows that it is the presence of the entire monsoon trough that impedes the movement of Rachel and steers the storm toward southwestern Taiwan especially before its landfall. In all, these results generally support the conceptual model with regard to the heavy rainfall mechanism proposed in a previous study. Moreover, this study further points out that it is the circulation associated with both Paul and the entire monsoon trough that affects the movement of Rachel. In addition, the analyses based on the no-terrain simulation depict the relationships among the moisture-rich air from the South China Sea associated with Rachel, relatively dry air from South China, and the mechanism of forming a warm and dry region to the eastern side of the Taiwan terrain, which greatly influences the heavy rainfall distribution in the event.

Collaborative Effects of Cold Surge and Tropical Depression–Type Disturbance on Heavy Rainfall in Central Vietnam

2008 ◽  
Vol 136 (9) ◽  
pp. 3275-3287 ◽  
Author(s):  
Satoru Yokoi ◽  
Jun Matsumoto
Keyword(s):  
Heavy Rainfall ◽  
Large Scale ◽  
Lower Troposphere ◽  
Heavy Rainfall Event ◽  
Wind Anomaly ◽  
Southerly Wind ◽  
Cold Surge ◽  
Tropical Depression ◽  
Orographic Rainfall ◽  
Central Vietnam

Abstract This paper reveals synoptic-scale atmospheric conditions over the South China Sea (SCS) that cause heavy rainfall in central Vietnam through case study and composite analyses. The heavy rainfall event discussed in this study occurred on 2–3 November 1999. Precipitation in Hue city (central Vietnam) was more than 1800 mm for these 2 days. Two atmospheric disturbances played key roles in this heavy rainfall. First, a cold surge (CS) northerly wind anomaly in the lower troposphere, originating in northern China near 40°N, propagated southward to reach the northern SCS and then lingered there for a couple of days, resulting in stronger-than-usual northeasterly winds continuously blowing into the Indochina Peninsula against the Annam Range. Second, a southerly wind anomaly over the central SCS, associated with a tropical depression–type disturbance (TDD) in southern Vietnam, seemed to prevent the CS from propagating farther southward. Over the northern SCS, the southerly wind anomaly formed a strong low-level convergence in conjunction with the CS northeasterly wind anomaly, and supplied warm and humid tropical air. These conditions induced by the CS and TDD are favorable for the occurrence of the heavy orographic rainfall in central Vietnam. The TDD can be regarded as a result of a Rossby wave response to a large-scale convective anomaly over the Maritime Continent associated with equatorial intraseasonal variability. Using a 24-yr (1979–2002) reanalysis and surface precipitation datasets, the authors confirm that the coexistence of the CS and TDD is important for the occurrence of heavy precipitation in central Vietnam. In addition, it is observed that CSs without a TDD do not lead to much precipitation.

On the Baiu frontal-scale rainfall characteristics and atmospheric conditions in the extremely heavy rainfall event around western Japan during 5-7 July 2018 with attention to the synoptic climatological viewpoint

2020 ◽  
Author(s):  
Kuranoshin Kato ◽  
Kengo Matsumoto ◽  
Takato Yamatogi ◽  
Chihiro Miyake
Keyword(s):  
Heavy Rainfall ◽  
Large Scale ◽  
Rainfall Amount ◽  
Heavy Rainfall Event ◽  
Atmospheric Conditions ◽  
Total Rainfall ◽  
Central Japan ◽  
Rainfall Characteristics ◽  
Western Japan ◽  
Eastern Japan

<p>   In East Asia, a significant subtropical front called the Baiu/Meiyu front appears just before midsummer and brings the huge rainfall there, greatly influenced by the Asian summer monsoon. However, large-scale atmospheric features and rainfall characteristics (such as convective or stratiform rain) as well as the total rainfall amount around the front show rather great differences between the western and eastern portions. For example, in the western part of the Japan Islands (especially around Kyushu District, the most western part) and the Changjiang River Basin in Central China, the more frequent appearance of the heavy rainfall events due to the organized deep convective clouds than in the eastern Japan results in the larger climatological precipitation amount there. This is greatly related to the larger moisture transport toward the western part of the Baiu front than toward the eastern part. On the other hand, the rainfall characteristics around the front in the eastern Japan tend to be largely influenced by the cool Okhotsk air mass with rather stable stratification. Furthermore, their year-to-year, intraseasonal and short-period variations including the diversity of the “heavy rainfall types” are also very large.</p><p>The extreme events in association with the Baiu/Meiyu activity are greatly reflected by the above variability of the frontal activity. Inversely, it would be also important viewpoint that detailed examination of some extreme events could lead to the better understanding of the “dynamic climatological features” of the Baiu/Meiyu system itself.</p><p>In such concept, the present study will examine the frontal-scale rainfall features and the atmospheric conditions for the extremely heavy rainfall event around the Baiu front in western to central Japan during 5-7 July 2018. Although it is the common feature for the Baiu frontal rainfall heavy in western Japan that the frequent appearance of the meso-scale intense rain bands results in the huge total rainfall amount there, it is noted that the extremely large total rainfall area was distributed much more widely up to the central Japan with also considerable contribution of the long-persistent “not-so-intense rain” there, as often found in the heavy rainfall in the eastern Japan. Our analyses of the atmospheric fields suggest that this extreme event seems to be characterized by the strong mixture both of the large-scale factors for activating the “western Japan Baiu” and the “eastern Japan Baiu”.</p><p>As for the precipitation analyses, the 10-minute precipitation data at many meteorological stations in the Japan Islands area were used to discuss on the frontal-scale “rainfall characteristics” as well as the total rainfall amounts.</p>

scholarly journals Remote effect of a tropical cyclone in the Bay of Bengal on a heavy-rainfall event in subtropical East Asia

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Sho Arakane ◽  
Huang-Hsiung Hsu ◽  
Chia-Ying Tu ◽  
Hsin-Chien Liang ◽  
Zheng-Yu Yan ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
East Asia ◽  
Bay Of Bengal ◽  
Heavy Rainfall ◽  
Rainfall Event ◽  
Heavy Rainfall Event

scholarly journals Improving weather forecasts by means of HPC solutions: the LEXIS approach in the 2020 Bitti flood event

2021 ◽  
Author(s):  
Paola Mazzoglio ◽  
Paolo Pasquali ◽  
Andrea Parodi ◽  
Antonio Parodi
Keyword(s):  
Real Time ◽  
Spatial Resolution ◽  
Early Warning ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Detection System ◽  
Daily Rainfall ◽  
Early Warning Systems ◽  
Flood Event ◽  
Heavy Rainfall Event

<p>In the framework of LEXIS (Large-scale EXecution for Industry & Society) H2020 project, CIMA Research Foundation is running a 3 nested domain WRF (Weather Research and Forecasting) model with European coverage and weather radar data assimilation over Italy. Forecasts up to 48 hours characterized by a 7.5 km resolution are then processed by ITHACA ERDS (Extreme Rainfall Detection System), an early warning system for the heavy rainfall monitoring and forecasting. This type of information is currently managed by ERDS together with two global-scale datasets. The first one is provided by NASA/JAXA GPM (Global Precipitation Measurement) Mission through the IMERG (Integrated Multi-satellitE Retrievals for GPM) Early run data, a near real-time rainfall information with hourly updates, 0.1° spatial resolution and a 4 hours latency. The second one is instead provided by GFS (Global Forecast System) at a 0.25° spatial resolution.<br>The entire WRF-ERDS workflow has been tested and validated on the heavy rainfall event that affected the Sardinia region between 27 and 29 November 2020. This convective event significantly impacted the southern and eastern areas of the island, with a daily rainfall depth of 500.6 mm recorded at Oliena and 328.6 mm recorded at Bitti. During the 28th, the town of Bitti (Nuoro province) was hit by a severe flood event.<br>Near real-time information provided by GPM data allowed us to issue alerts starting from the late morning of the 28th. The first alert over Sardinia based on GFS data was provided in the late afternoon of the 27th, about 40 km far from Bitti. In the early morning of the 28th, a new and more precise alert was issued over Bitti. The first alert based on WRF data was instead provided in the morning of the 27th and the system continued to issue alerts until the evening of the 29th, confirming that, for this type of event, precise forecasts are needed to provide timely alerts.<br>Obtained results show how, taking advantage of HPC resources to perform finer weather forecast experiments, it is possible to significantly improve the capabilities of early warning systems. By using WRF data, ERDS was able to provide heavy rainfall alerts one day before than with the other data.<br>The integration within the LEXIS platform will help with the automatization by data-aware orchestration of our workflow together with easy control of data and workflow steps through a user-friendly web interface.</p>

scholarly journals Synoptic study of extremely heavy rainfall events over lower Yamuna catchment : Some cases

MAUSAM ◽  
2021 ◽  
Vol 64 (2) ◽  
pp. 265-280
Author(s):  
MEHFOOZ ALI MEHFOOZALI ◽  
U.P. SINGH ◽  
D. JOARDAR ◽  
NIZAMUDDIN NIZAMUDDIN
Keyword(s):  
Bay Of Bengal ◽  
Heavy Rainfall ◽  
Extreme Rainfall ◽  
Low Pressure ◽  
Crop Damage ◽  
Local Conditions ◽  
Rainfall Events ◽  
Synoptic Conditions ◽  
Heavy Rainfall Events ◽  
Low Pressure Systems

vR;f/kd o"kkZ gksus ds dkj.k HkwL[kyu gksrk gS vDlekr ck<+ vk tkrh gS vkSj Qly dks {kfr igq¡prh gSA lekt] vFkZO;oLFkk vkSj i;kZoj.k ij bldk cgqr nq"izHkko iM+rk gSA i;kZoj.kh; vkSj flukWfIVd fLFkfr;ksa ds mRiUu gksus ls  vR;f/kd vFkok cgqr Hkkjh o"kkZ gksus ds dkj.k Hkkjr esa nf{k.k if’peh ekulwu _rq ds nkSjku vf/kdk¡’kr% ck<+ vkrh gSA bl 'kks/k i= esa izeq[k flukWfIVd dkj.kksa dk irk yxkus dk iz;kl fd;k x;k gS tks y?kq vof/k iwokZuqeku ds {ks= esa fodflr iwokZuqeku rduhd vkSj vk/kqfud izs{k.kkRed izkS|ksfxdh ij vk/kkfjr o"kZ 1998&2010 dh vof/k dh bl o"kkZ  vkSj ok;qeaMyh; iz.kkfy;ksa ds e/; laca/kksa ds fo’ys"k.k ds ek/;e ls ;equk ds fupys tyxzg.k {ks= ¼,y-okbZ-lh-½ esa vR;f/kd Hkkjh o"kkZ dh ?kVukvksa ds fy, mRrjnk;h gSA bl v/;;u ls ;g irk pyk gS fd  bl {ks= esa caxky dh [kkM+h esa fuEu nkc iz.kkfy;ksa dk cuuk izeq[k dkjd gS fuLlansg ;fn LFkkuh; fLFkfr;k¡ izHkkoh gks tSlsa fd xehZ dk c<+uk rks ogk¡ ij Hkkjh o"kkZ gksrh gSA lkekU;r% caxky dh [kkM+h esa fuEu vcnkc iz.kkfy;k¡ ¼pØokr] vonkc] fuEu vonkc {ks= vkfn tSls ¼,y-ih-,l-½ fodflr gqbZ tks if’pe ls mRrjh  if’peh fn’kk dh vksj c<+h rFkk ;equk ds fupys tyxzg.k ¼,y-okbZ-lh-½ {ks= esa igq¡phA ,slh ?kVukvksa ds fy, mRrjnk;h mifjru  ok;q pØokrh ifjlapj.k ¼lkblj½ ds izHkko ls ogha ij ,y- ih- ,l- Hkh cu ldrk gSA ,slh iz.kkyh ls bDds&nwDds LFkkuksa ij vR;f/kd Hkkjh o"kkZ dh ?kVuk,¡ ¼lkekU;r% iz.kkyh ds nf{k.k if’pe {ks= esa½ vkSj dqN LFkkuksa ij Hkkjh ls cgqr Hkkjh o"kkZ gqbZ ftlds dkj.k ck<+ vkbZA ;fn ;equk ds fupys tyxzg.k ¼,y-okbZ-lh-½ {ks= esa ,y-ih-,l- fuf"Ø; ;k /khek iM+ tkrk gS rks bl izdkj dh o"kkZ dh ?kVukvksa dh laHkkouk c<+ ldrh gSA ,y-ih-,l- ds vkxs c<+us dk lgh iwokZuqeku nsus ds fy, vkj-,l-,e-lh- ¼Hkkjr ekSle foKku foHkkx½ ubZ fnYYkh ds iwoZuqeku :i js[kk ds ,u-MCY;w-ih- mRikn@72] 48 vkSj 24 ?kaVksa ds iou pkVZ lgh lk/ku ik, x, gSaA vR;f/kd o"kkZ dh ?kVukvksa ds iwokZuqeku esa bl izdkj dh lwpuk nsus ls iwokZuqekudrkvksa dks fuf’pr :i ls lgh iwokZuqeku feysxk rkfd ftyk izkf/kdkjh le; jgrs vkink dh rS;kjh ds fy, vko’;d ewyHkwr lqfo/kk,¡ miyC/k djk ldsaA  Extreme rainfall results in landslides, flash flood and crop damage that have major impact on society, the economy and the environment. During southwest monsoon season, flood mostly occurs in India due to extremely or very heavy rain that originates from environmental and   synoptic conditions. An attempt has been made to identify the main synoptic reasons, which are responsible for extremely heavy rainfall events over Lower Yamuna catchment (LYC) through the analysis of the relationship between this rainfall and atmospheric systems for the period 1998-2010 based on modern observational technology and developed forecasting technique in the field of short range prediction. The finding of this study show that the major factor have is the arrival of Bay of Bengal low pressure systems in this region, of course if the ascent local conditions such as heat occur, causing the heaviest rains there. The low pressure systems (LPS like, Cyclone, depression, low pressure area etc.) developed generally over Bay of Bengal moved in west to north-westwards direction and reached over the LYC region. Also LPS may be formed in situ under the influence of upper air cyclonic circulation (cycir) responsible for such events. Such system yield extremely heavy rainfall events (generally in the south-west sector of the system) at isolated places and heavy to very heavy rainfall at a few places and there by caused flood situation. The possibility of occurrence of such type of rainfall would be higher if the LPS is either stagnate or slow over LYC region. The NWP products of RSMC (IMD) New Delhi forecast contours / wind charts for 72, 48 & 24 hrs were found good tool for accurate forecast position of the movement of the LPS. Such information certainly facilitate to forecaster in prediction of extreme rainfall events more accurately so that district authorities may set up necessary infrastructures for disaster preparedness in time.

Numerical Experiments on Spatially Averaged Precipitation in Heavy Rainfall Event Using the WRF Model

2015 ◽  
Vol 10 (3) ◽  
pp. 436-447 ◽  
Author(s):  
Yuji Sugihara ◽  
◽  
Sho Imagama ◽  
Nobuhiro Matsunaga ◽  
Yukiko Hisada ◽  
...  
Keyword(s):  
Numerical Experiments ◽  
Heavy Rainfall ◽  
Wrf Model ◽  
Analysis Data ◽  
Rainfall Event ◽  
Weather Research And Forecasting ◽  
Heavy Rainfall Event ◽  
Spatial Averaging ◽  
Hourly Rainfall ◽  
Precipitation Analysis

It is difficult to forecast hourly rainfall locally even using the latest meteorological models, although hourly rainfall averaged spatially to some extent can be used for calculating practical rainfall. This study conducts numerical experiments with triple nesting on the 2012 heavy rainfall event in northern Kyushu using the weather research and forecasting (WRF) model and examines the features of hourly rainfall averaged spatially. The dependence of rainfall is averaged spatially on a spatial averaging scale and clarified by comparing rainfall calculated by simulation using the WRF model with radar/AMeDAS precipitation analysis data. This study’s findings indicate the effective spatial averaging scale making relative error of calculated values to the observed ones minimum.

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