scholarly journals EI- Nino and tropical storm tracks over Bay of Bengal during post monsoon season

MAUSAM ◽  
2021 ◽  
Vol 42 (3) ◽  
pp. 257-260
Author(s):  
AKHILESH GUPTA ◽  
A. MUTHUCHAMI

The role of EI-Nino in modulating tropical cyclone motion over Bay of Bengal during post monsoon season has been examined. Storms which formed during the years 1901-1987 have been classified into recuriving or those of which crossing north of 17° N and non-recurving or those of which crossing south of 17° N the east coast of India. It has been found that in most of the cases (87 %) during EI-Nino years, the tropical cyclones which formed over Bay of Bengal crossed south of 17° N, i.e. south Andhra Pradesh Tamil Nadu coast, whereas tropical cyclones, ed during the year prior to the EI-Nino years [El- Nino (-1 ) year] are seen crossing mostly (in 79% of cases) either h of 17°N or recurving m northeastward direction. In other years this kind of behaviour is not generally onseerved. The correlation between southern oscillation indices and the fractional values of storms crossing south of 170 N for the period 1901-1987 (n=87) is found to be ---0.63 which is significant at 1 per cent level.

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Somenath Dutta ◽  
Geena Sandhu ◽  
Sanjay G Narkhedkar ◽  
Sunitha Devi

The study discusses the energetic aspects of tropical cyclones formed over Arabian Sea (AS) and Bay of Bengal (BOB) during the period from 1991 till 2013 and aims at bringing out climatology of the energetics of tropical cyclones over Indian Seas. Total 88 cyclones that developed over the Indian Seas during the recent decade of 1991-2013 have been studied. These intense systems are categorized on the basis of their formation region and season of formation. It is seen that during the study period, the frequency of formation of cyclones over BOB is twice that over AS which is consistent with the climatology of the regions. Further, it is noticed that over both the regions, they are more frequently formed in the post monsoon period compared to pre monsoon. The trend analysis of the frequency of cyclones forming over both basins, season wise shows that the overall trend for both basins is of just decreasing type. However, for Arabian Sea; the decreasing trend is more apparent in the post monsoon season, whereas in the case of the Bay of Bengal the decreasing trend is more evident in the pre monsoon season. Various energy terms, their generation and conversion terms have been computed using NCEP/NCAR reanalysis data. Day to day quantitative analysis of these parameters is studied critically during various stages of the cyclones. The composites of these categorized systems are formed and studied. The formative, intensification and dissipation stages showed variations in their energy terms.


MAUSAM ◽  
2022 ◽  
Vol 63 (3) ◽  
pp. 469-474
Author(s):  
G.K. DAS ◽  
S.K. MIDYA ◽  
G.C. DEBNATH ◽  
S.N. ROY

In this paper a simple relationship is employed to investigate relative impacts on the movement and landfall of tropical cyclone in the Bay of Bengal region when geopotential height of different troposphere levels is used as an input. Five tropical cyclone during pre-monsoon and post-monsoon season over the Bay of Bengal region has been selected for the study. The RS/RW data of coastal stations namely Kolkata (Dumdum), Dhaka, Agartala, Bhubaneswar, Visakhapatnam, Machlipatnam, Chennai and Karaikal has been collected for the period of the cyclones under study. The geopotential height of different standard levels has been plotted against the time for the stations for every cyclone. The study suggests that the cyclone moves towards and cross near the station having relatively steeper decrease in geopotential height upto mid tropical level followed by increased in geopotential height.


2021 ◽  
Author(s):  
Zhi Li ◽  
Yuhuan Xue ◽  
Yue Fang ◽  
Kuiping Li

AbstractUnlike other tropical ocean basins, the Bay of Bengal (BoB) has two tropical cyclone (TC) seasons: a pre-monsoon season (Pre-MS) and a post-monsoon season (Post-MS). More interestingly, during the period from 1981 to 2016, the global maximum and minimum formation rates of super cyclones (SCs, categories 4 and 5) occurred in the Pre-MS and Post-MS, respectively, in the BoB. Methods including Butterworth filter, box difference index analysis and quantitative diagnosis were utilized herein to detect what and how background environmental factors cause significantly different SC formation rates between the Pre- and Post-MS. Diagnosis results revealed that the vertical temperature difference (VTD) mainly determines whether TCs can develop into SCs during the Post-MS, similar to Pre-MS. It’s in agreement with previous studies demonstrating that the VTD is controlled by the low-level temperature during the Post-MS but is determined by the upper-level temperature during the Pre-MS. The results also revealed that the background sea surface temperature is much higher in the Pre-MS than in the Post-MS and forces higher 1000 hPa-level air temperature. Additionally, there is higher saturated specific humidity (qs) due to the higher temperature in the Pre-MS. The differences in the bottom-level temperature and qs cooperate to predominantly contribute to the significant difference in Vpot2, which could denote the maximum potential intensity of TC, eventually leading to the remarkably different SC formation rates between the Pre- and Post-MS in the BoB.


2020 ◽  
Author(s):  
Sreenath Avaronthan Veettil ◽  
Abhilash Sukumarapillai ◽  
Vijaykumar Pattathil

Abstract. The El-Nino Southern Oscillation (ENSO) modulates the lightning flash rate (LFR) variability over India during pre-monsoon, monsoon, and post-monsoon seasons. The impact of ENSO phases on the LFR over the Indian subcontinent is studied using the data obtained from Optical Transient Detector and Lightning Imaging Sensors onboard the TRMM satellite. The study shows that irrespective of ENSO phases, the LFR is maximum over northeast India (NEI) in the pre-monsoon season, and the peak is shifted to the north of northwest India (NNWI) in the monsoon season. The LFR over Northeast India (NEI) and southern peninsular India (SPI) intensified (reduced) during the warm (cold) phase of ENSO in the pre-monsoon season. In the monsoon season, NEI (NNWI) is showing above normal LFR in the warm (cold) ENSO phase. It is fascinating that the three hotspots of LFR over the Indian land region became more prominent in the last decade of the monsoon season. A widespread increase of LFR is observed all over India during the warm phase of ENSO in the post-monsoon season. However, a marked increase in the LFR is confined mostly over the NNWI in the cold ENSO phase. The subtropical westerly jet stream is shifted south in association with the warm phase, and an increase in the geopotential height (GPH) is also noticed all over India in the same period. ENSO’s warm phase indirectly influences the LFR over India during the post-monsoon season by pushing the mean position of subtropical westerly towards south latitudes.


Check List ◽  
2011 ◽  
Vol 7 (1) ◽  
pp. 083
Author(s):  
Palanisamy Satheeshkumar ◽  
Anisa B. Khan

Cantharus tranquebaricus (Gmelin, 1791) is reported for the first time in Pondicherry mangroves, southeast coast of India. Three adult specimens have been found in the Thengaithittu lagoon during post monsoon season of 2009. It is a characteristic species of molluscan fauna of the Bay of Bengal and the descriptions of the shell are provided.


MAUSAM ◽  
2022 ◽  
Vol 64 (1) ◽  
pp. 171-188
Author(s):  
D.R. PATTANAIK ◽  
M. MOHAPATRA ◽  
B. MUKHOPADHYAY ◽  
AJIT TYAGI

o"kZ 2010 esa ekulwuksRrj _rq ds nkSjku nks pØokrh; rwQku fufeZr gq, FksA tSls ‘fxjh’ uked vfr izpaM pØokrh; rwQku ¼oh-,l-lh-,l-½ 19 vDrwcj dks fufeZr gqvk vkSj ;g 22 rkjh[k dks E;kaekj leqnz rV dks ikj dj x;k vkSj nwljk ‘tky’ uked izpaM pØokrh; rwQku ¼,l-lh-,l-½ 2 uoacj dks fufeZr gqvk vkSj ;g psUuS ds mRrjh Hkkx ds lehi mRrjh rfeyukMq & nf{k.kh vka/kz izns’k ds leqnzh rVksa dks 07 uoacj dks ikj dj x;k ftldh otg ls rfeyukMq vkSj nf{k.kh vka/kz izns’k ds leqnz rVh; {ks=ksa esa u dsoy rhoz iou ls cfYd mlls gqbZ Hkkjh o"kkZ ls Hkkjh {kfr gqbZA okLrfod le; foLr`r {ks= iwokZuqeku xR;kRed fHkUurkvksa ds lkIrkfgd vkSlr ds vk/kkj ij nks lIrkg ds fy, rS;kj fd, x, gSa tks- bZ- lh- ,e- MCY;w- ,Q-] ,u- bZ- lh- ih- rFkk nksuksa ds 2 ekWMYl vkSlr ¼2 ,e- ,- oh- bZ-½ ds ;qfXer ekWMy ifj.kke ij vk/kkfjr gSaA lkIrkfgd vkSlr] iou vkSj lkisf{kd Hkzfeyrk ds 5&11 fnuksa ds izpkyukRed iwokZuqeku 14 vDrwcj 2010 ds vkjafHkd fLFkfr ij vk/kkfjr gSa ftlls irk pyk gS fd 18&24 vDrwcj dh vof/k ds nkSjku e/; caxky dh [kkM+h ds Åij fuEu nkc dk pØokrh; ldqZys’ku Fkk tks vfr izpaM pØokrh; rwQku ‘fxjh’ ds leku FkkA ‘tky’ uked pØokr  dh mRifRr dk 2 ,e- ,- oh- bZ- esa vPNh rjg irk yxk fy;k x;k FkkA bldk iwokZuqeku 12&18 fnuksa ds fy, oS/k Fkk vkSj ;g 21 vDrwcj 2010 dh vkjafHkd fLFkfr ij vk/kkfjr FkkA 2 ,e- ,- oh- bZ- iwokZuqeku 1&7 uoacj rd ds fy, oS/k Fkk tks 28 ,oa 21 vDrwcj dh vkjafHkd fLFkfr;ksa ij vk/kkfjr Fkk ¼buds iwokZuqeku dh vof/k Øe’k% 5&11 fnuksa rFkk 12&18 fnuksa dh Fkh½ ftlesa Li"V :i ls n’kkZ;k x;k gS fd rfeyukMq leqnz rV vkSj blls yxs gq, vka/kz izns’k ds {ks= esa izsf{kr dh xbZ folaxfr;ksa ls dkQh vf/kd ?kukRed o"kkZ folaxfr;k¡ ns[kh xbZ gSaA bl izkjafHkd v/;;u esa vkxs crk;k x;k gS fd lkIrkfgd pØokrh; Hkzfeyrk ds  ekWMy iwokZuqekuksa dh vf/kdre folaxfr =qfV yxHkx &0-8 ls &1-0 × 10&5 izfr lSds.M dks fuEu LRkjh; vf“lj.k folaxfr yxHkx &0-8 ls &1-0 × 10&5 izfr lSds.M ds lkFk feyus ij m".kdfVca/kh pØokr cuus dh laHkkouk curh gSA rFkkfi bl flLVe ds pØokr ds :i esa rhozhdj.k gsrq Fkzs’kgksYM oSY;w dh igpku djus ds fy, vkSj vf/kd ekeyksa ds fo’ys"k.k djus dh vko’;drk gSA There were two cyclonic storms formed during the post monsoon season of 2010 viz., “Giri” a very severe cyclonic storm (VSCS) formed on 19th October  and  crossed the Myanmar coast on 22nd and the second system “Jal” a severe cyclonic storm (SCS) formed on 2nd November and  crossed north Tamil Nadu-south Andhra Pradesh coasts, close to north of Chennai on 7th November, which caused lot of damage in Tamil Nadu and south Andhra Pradesh coast associated with not only strong wind but also due to associated heavy rainfall.           The real time extended range forecasts in terms of weekly mean of dynamical variables are prepared for two weeks based on the coupled model outputs from ECMWF, NECP and the 2 models average (2MAVE) of both. The operational forecast for days 5-11 of weekly mean wind and relative vorticity based on 14th October, 2010 initial condition indicates cyclonic circulation at low level over the central Bay of Bengal during the period from 18-24 October associated with the very severe cyclone “Giri”. The genesis of the cyclone “Jal” was very much captured in the 2MAVE forecast valid for 12-18 days forecast based on the initial condition of 21st October, 2010. The 2MAVE forecast valid for 1-7 November based on 28 October and 21 October initial conditions (with forecast period of days 5-11 and days 12-18 respectively) also clearly indicated large positive rainfall anomalies over Tamil Nadu coast and adjoining coastal Andhra Pradesh region like that of observed rainfall anomalies. This preliminary study further indicates that the model forecasts anomaly of weekly cyclonic vorticity maximum of about   2.5´10-5 sec-1 combined with a low level convergence anomaly of about -0.8 to -1.0 ´ 10-5 sec-1 may lead to formation of a tropical cyclone.  However, more number of cases required to be analysed for the proper identification of the threshold values for intensification of the system into a cyclone. 


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