scholarly journals DIAGNOSTIC ANALYSIS OF CATASTROPHIC FLOOD OVER EASTERN INDIA IN JULY 2017 - A CASE STUDY

MAUSAM ◽  
2021 ◽  
Vol 71 (3) ◽  
pp. 513-522
Author(s):  
Sharma R S ◽  
Mandal B K ◽  
Das G K
Keyword(s):  
Heavy Rainfall ◽  
West Bengal ◽  
Monsoon Season ◽  
Geographical Location ◽  
River Basins ◽  
Southwest Monsoon ◽  
Eastern India ◽  
Monsoon Period ◽  
Indian States ◽  
South West Monsoon

Floods are very common in eastern India during southwest monsoon season. It brings a lot of misery to the people of this region. Every year eastern Indian states namely West Bengal, Odisha and Bihar witness such types of flood during monsoon period. Major river basins in eastern India are Ganga river basin in Bihar and West Bengal area, Odisha has three river basins namely Mahanadi, Subarnarekha, Brahmani and Baitarani        [Fig. 1(a)]. As majority of tributary rivers of Ganga passing through Bihar and West Bengal; these two states are more prone to massive flood during monsoon season. The abnormal occurrence of rainfall generally causes floods. It occurs when surface runoff exceeds the capacity of natural drainage. The heavy rainfall is frequently occurring event over the area during South-West Monsoon (SWM) every year. The geographical location of the area, orography and its interaction with the basic monsoon flow is considered as one of prime factors of these heavy rainfall activities. Synoptically, the latitudinal oscillation of eastern end of the Monsoon Trough and the synoptic disturbances formed or passing over the eastern India region and / or its neighbourhood that brings moisture laden Easterly or South-Easterly winds over the area are the main causes responsible for heavy rainfall in this area.

scholarly journals Verification of operational rainfall forecast over eastern India during southwest monsoon season

MAUSAM ◽  
2021 ◽  
Vol 68 (2) ◽  
pp. 327-334
Author(s):  
G. C. DEBNATH ◽  
G. K. DAS
Keyword(s):  
West Bengal ◽  
Monsoon Rainfall ◽  
Monsoon Season ◽  
Skill Score ◽  
Southwest Monsoon ◽  
Summer Monsoon Rainfall ◽  
Eastern India ◽  
Rainfall Forecast ◽  
Heidke Skill Score ◽  
Southwest Monsoon Season

The Indian summer monsoon rainfall forecast and its verification has a direct impact on various sectors of public interest besides economy of the country. The present study highlights the verification of distribution forecast of synoptic method issued daily for six met subdivisions, comprising of five states of eastern India namely West Bengal, Sikkim, Bihar, Jharkhand and Odisha. Three years monsoon season rainfall data from 2011 through 2013 are used for the study area. The distribution-oriented verification is done for different rainfall classes like dry, isolated, scattered, fairly widespread and widespread to understand the usefulness of the synoptic method. Statistics are presented for both combined classes of Percentage Correct (PC) and Heidke Skill Score (HSS) of the met subdivision wise forecast and PC, POD and CSI for individual classes. It has been observed that among the met subdivision the efficiency of the method is highest in Sub Himalayan West Bengal (SHWB) & Sikkim followed by Gangetic West Bengal (GWB), Odisha, Jharkhand and Bihar.

scholarly journals Study of rainfall features over Goa state during southwest monsoon season

MAUSAM ◽  
2021 ◽  
Vol 61 (2) ◽  
pp. 155-162
Author(s):  
S. M. METRI ◽  
KHUSHVIR SINGH
Keyword(s):  
Heavy Rainfall ◽  
Monsoon Season ◽  
Southwest Monsoon ◽  
Annual Rainfall ◽  
Statistical Parameters ◽  
Maximum Rainfall ◽  
Rainfall Events ◽  
Average Rainfall ◽  
Southwest Monsoon Season ◽  
Heavy Rainfall Events

In this paper the rainfall features at different raingauge stations of Goa state have been studied for the period of 30 years. The statistical parameters such as mean monthly rainfall, Standard Deviation and Coefficient of Variation have been computed for each raingauge station of Goa. Some heavy rainfall events during the period have also been studied. The study shows the significant rising trend of rainfall towards the eastern parts of Goa. Goa experiences an average rainfall of about 330 cm annually and around 90% of annual rainfall occurs during southwest monsoon season i.e. (June to September). Studies revealed that most of heavy rainfall events caused due to active off-shore trough and low pressure systems formed over southeast Arabian Sea. It has also come out from the study that the orography of Goa plays an important role in rainfall distribution. Valpoi receives maximum rainfall due to its orographic effect.

scholarly journals Present operational long range forecasting system for southwest monsoon rainfall over India and its performance during 2010

MAUSAM ◽  
2021 ◽  
Vol 62 (2) ◽  
pp. 179-196
Author(s):  
D.S. PAI ◽  
O.P. SREEJITH ◽  
S.G. NARGUND ◽  
MADHURI MUSALE ◽  
AJIT TYAGI
Keyword(s):  
Monsoon Season ◽  
Central India ◽  
Southwest Monsoon ◽  
Northeast India ◽  
Peninsular India ◽  
South West ◽  
Operational Forecasts ◽  
Geographical Regions ◽  
South West Monsoon ◽  
West Monsoon

At present, India Meteorological Department (IMD) issues various monthly and seasonal operational forecasts for the south-west monsoon season using models based on latest statistical techniques with useful skill. Operational models are reviewed regularly and improved through in house research activities. For the forecasting of the south-west monsoon season (June – September) rainfall over the country as a whole, a newly introduced statistical ensemble forecasting system is used. In addition, models have been developed for the forecast of the monsoon season rainfall over four geographical regions (NW India, NE India, Central India and South Peninsula) of the country and forecast for the rainfall over the second half of the monsoon season over the country as a whole. Models have also been developed for issuing operational forecast for the monthly rainfall for the months of July, August & September over the country as a whole. Operational forecasts issued by IMD for 2010 south-west monsoon rainfall have been discussed and verified. In addition, the experimental forecasts for the season rainfall over the country as a whole based on bothstatistical and dynamical models received from various climate research institutes within the country other than IMD arealso discussed. The operational monthly and seasonal long range forecasts issued for the 2010 southwest monsoon season for the country as a whole were accurate. However, forecasts for the season rainfall over the 4 geographical regions (Northwest India, Central India, Northeast India and south Peninsular India) were not accurate as the forecast for South Peninsular India overestimated the actual rainfall and that for northeast India underestimated the actual rainfall. The experimental forecasts for the season rainfall over the country as whole from various climate research institutes within the country showed large variance (91 % - 112% of LPA).

scholarly journals QPF Model for lower Yamuna catchment, synoptic analogue method

MAUSAM ◽  
2021 ◽  
Vol 62 (1) ◽  
pp. 27-40
Author(s):  
MEHFOOZ ALI ◽  
U. P. SINGH ◽  
D. JOARDAR
Keyword(s):  
Monsoon Season ◽  
Skill Score ◽  
Southwest Monsoon ◽  
Precipitation Forecast ◽  
Synoptic Situation ◽  
Analogue Model ◽  
Quantitative Precipitation Forecast ◽  
South West Monsoon ◽  
Heidke Skill Score ◽  
Southwest Monsoon Season

The paper formulates a synoptic analogue model for issuing Quantitative Precipitation Forecast (QPF) for Lower Yamuna Catchment (LYC) based upon eleven years data (1998-2008) during southwest monsoon season. The results so derived were verified with realized Average Areal Precipitation (AAP) for the corresponding synoptic situation during 2009 southwest monsoon season. The performance of the model was observed Percentage Correct (PC) up to 86 % and for extreme events showed 100% correct with Heidke Skill Score (HSS) value 0.9. The experience during south west monsoon 2009 has shown that Synoptic analogue model can produce 24 hours advance QPF with accuracy and greater skill to facilitate the flood forecasters of Central Water Commission.

Seasonal foraging activity of stingless bee Tetragonula travancorica Shanas and Faseeh (Hymenoptera: Apidae: Meliponini)

ENTOMON ◽  
2021 ◽  
Vol 46 (2) ◽  
pp. 149-166
Author(s):  
Lincy Abraham ◽  
S. Shanas
Keyword(s):  
Weather Conditions ◽  
Southwest Monsoon ◽  
Stingless Bee ◽  
Foraging Activity ◽  
Monsoon Period ◽  
North East ◽  
South West ◽  
South West Monsoon ◽  
Two Peaks ◽  
West Monsoon

The foraging hive activity of stingless bee Tetragonula travancorica Shanas and Faseeh was studied from November 2018 to August 2019. The activity varied between the seasons, weather conditions and time hours of study. The outgoing and incoming pollen foragers exhibited two peaks in activity, from 0800-1200 h (first) and during 1500-1600 h (second). The activity of incoming non-pollen foragers displayed only one distinct peak between 1000-1200 h except during the southwest monsoon period. The greatest activity was recorded during the dry season (January-May), followed by the south-west monsoon (June-August) and north-east monsoon (November- December) seasons. Maximum overall activity was recorded during hotter months February, March and April while the lowest was observed in January and December. At any season or time, the number of incoming foragers without pollen was greater than pollen foragers.

scholarly journals Heavy rainfall analysis over Teesta catchment and adjoining areas of Sub-Himalayan West Bengal and Sikkim

MAUSAM ◽  
2021 ◽  
Vol 71 (1) ◽  
pp. 133-144
Author(s):  
RAHA G N ◽  
BANDYOPADHYAY S ◽  
DAS S
Keyword(s):  
Heavy Rainfall ◽  
West Bengal ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Primary Objective ◽  
Analogue Model ◽  
River Catchment ◽  
Rainfall Analysis ◽  
Hilly Region ◽  
Good Agreement

Heavy rainfall (HRF) forecasting in hilly region is always a challenge to the operational forecasters. Synoptic Analogue Model (SAM) is considered as one of the useful tools for HRF forecasting in topographically influenced hilly regions. In every monsoon season, the Teesta river catchment and its adjoining areas in Sub-Himalayan West Bengal and Sikkim (SHWB-S) generally receive several events of HRF. With the primary objective to find the method to issue HRF warning over Teesta river catchment and adjoining areas in SHWB-S, a SAM has been developed by analyzing 18 years (1998-2015) data comprising prevailing synoptic situations affecting the area and daily rainfall data of subsequent day of HRF. In addition, impact of different synoptic systems on the distribution of HRF has also been studied. The results revealed that there exists a good agreement between daily HRF warnings issued with the corresponding HRF event observed over this region on the next day.

scholarly journals Moisture trajectories during heavy rainfall events using Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model

2021 ◽  
Vol 2070 (1) ◽  
pp. 012066
Author(s):  
S Aryalakshmi ◽  
Dhanya Madhu
Keyword(s):  
Single Particle ◽  
Moisture Transport ◽  
Heavy Rainfall ◽  
Back Trajectory ◽  
Hysplit Model ◽  
Monsoon Period ◽  
Back Trajectories ◽  
North East ◽  
The North ◽  
South West Monsoon

Abstract Heavy rainfall inducing other catastrophic events are frequently experienced globally. Understanding the mechanisms of moisture transport during such events will help in furthering our knowledge about such systems. In the current study, estimation of most likely moisture trajectoriesis performed using back trajectory analyses. Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model available from National Oceanic and Atmospheric Administration’s (NOAA) Air Resources Laboratory (ARL) is used for the purpose. A preliminary analysis is conducted by calculating the frequencies of back trajectories from two locations in Kerala for three heavy rainfall cases. The analysis indicates that both the locations have similar pattern of moisture trajectories during the cases occurring in south west monsoon and pre monsoon periods. However, a change in the behaviour of the trajectories for the two locations is observed for the case during the north east monsoon period. Since this study involved only individual cases, robust conclusions cannot be made based on this for the dynamics of moisture transport for these locations. More detailed analysis will follow this preliminary study in future for the purpose.

scholarly journals Variability of south west monsoon rainfall in West Bengal : An application of principal component analysis

MAUSAM ◽  
2021 ◽  
Vol 65 (4) ◽  
Author(s):  
PIJUSH BASAK
Keyword(s):  
Principal Component Analysis ◽  
West Bengal ◽  
Monsoon Rainfall ◽  
Principal Component ◽  
Component Analysis ◽  
Southwest Monsoon ◽  
Spatial And Temporal Variability ◽  
Annual Variations ◽  
South West Monsoon ◽  
Southwest Monsoon Rainfall

The principal component analysis is utilized to understand the spatial and temporal variability of monsoonal rainfall. The southwest monsoon rainfall data of West Bengal, situated over 21 stations widely spread over the state, has been analyzed for a period of 60 years for inter-annual variations. A coherent subset of 8 north and 13 south stations has been studied separately to produce statistically significant inter-annual signals. It is observed that the above/below transition is quite significant both for station rainfalls and principal components for state-wise and coherent zone analysis.

scholarly journals A satellite based study of pre-monsoon thunderstorms (Nor’westers) over eastern India and their organization into mesoscale convective complexes

MAUSAM ◽  
2021 ◽  
Vol 63 (1) ◽  
pp. 29-54
Author(s):  
AJIT TYAGI ◽  
D.R SIKKA ◽  
SUMAN GOYAL ◽  
MANSI BHOWMICK
Keyword(s):  
West Bengal ◽  
India Meteorological Department ◽  
Eastern India ◽  
Indian States ◽  
North East ◽  
Ne India ◽  
Mesoscale Convective ◽  
History Of ◽  
Science Community ◽  
Convective Cells

Nor’wester studies have a long history of climatological, synoptic and radar observations. These studies have been briefly mentioned and the field programs for the study of Nor’westers implemented in India Meteorological Department (IMD) from 1931-1941 have been touched upon. Indian atmospheric science community organized a multi-year STORM program during 2007-2010 to understand the formation of these severe local storms and also understand their dynamics through modeling. An attempt is made to use INSAT Infrared and Visible imageries to document the convective cells which developed over Eastern and North-East (NE) Indian states and adjoining countries of Bangladesh, Bhutan and Nepal for the year 2009. Also convective cells which organized themselves into Mesoscale Convective Complexes (MCCs) for the four years period 2007-2010 have been studied. It is found that by and large Eastern India (Jharkhand, Orissa, Sub Himalayan West Bengal and Bangladesh) is responsible for the initiation of convection. Development occurs as the cells propagate over the neighbouring areas of Bangladesh and NE India. Important observations with regard to initiation, maturity and dissipation etc. of the MCCs are provided. It is suggested that half hourly to hourly monitoring of convection can be accomplished by using INSAT imagery, along with multiple overlapping radar coverages, which could help in nowcasting of convective cells. Synoptic and thermodynamic forcing can help as broad guidance. The only effective way for effective warning is nowcasting using satellite and multiple radar coverage.

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