scholarly journals Seasonal Nature and Trends of Tropical Cyclone Frequency and Intensity over the North Indian Ocean

2020 ◽  
Vol 15 (3) ◽  
pp. 526-534
Author(s):  
Abhisek Pal ◽  
Soumendu Chatterjee
Keyword(s):  
Time Series ◽  
Tropical Cyclone ◽  
Indian Ocean ◽  
Monsoon Season ◽  
North Indian Ocean ◽  
Post Monsoon ◽  
The North ◽  
Increasing Trend ◽  
Post Monsoon Season ◽  
Cyclone Frequency

Tropical cyclone (TC) genesis over the North Indian Ocean (NIO) region showed significant amount of both spatial and temporal variability.It was observed that the TC genesis was significantly suppressed during the monsoon (June-September) compared to pre-monsoon (March-May) and post-monsoon (October-December) season specifically in terms of severe cyclonic storms (SCS) frequency. The Bay of Bengal (BoB) was characterized by higher TC frequency but lower intensity compared to the Arabian Sea (AS). It was also observed that the TC genesis locations were shifted significantly seasonally.The movement of the TCs also portrayed some significant seasonal differences. The pre-monsoon and post-monsoon season was responsible for generating TCs with higher values of accumulated cyclone energy (ACE) compared to the monsoon. The time series of TC frequency showed a statistically significant decreasing trend whereas the time series of ACE showed astatistically significant increasing trend over the NIO.

scholarly journals Modulation of cyclonic disturbances over the north Indian Ocean by Madden - Julian oscillation

MAUSAM ◽  
2021 ◽  
Vol 62 (3) ◽  
pp. 375-390
Author(s):  
M. MOHAPATRA ◽  
S. ADHIKARY
Keyword(s):  
Indian Ocean ◽  
Bay Of Bengal ◽  
Monsoon Season ◽  
Phase 1 ◽  
North Indian Ocean ◽  
Maritime Continent ◽  
Phase 3 ◽  
Post Monsoon ◽  
The North ◽  
Post Monsoon Season

The relationship of genesis and intensity of cyclonic disturbances (CDs) over the north Indian Ocean with the Madden – Julian Oscillation (MJO) has been examined using 33 years (1975 - 2007) data of MJO index and best track of (CDs) developed by India Meteorological Department (IMD). The MJO index based on outgoing long wave radiation (OLR) and zonal wind in upper (200 hPa) and lower (850 hPa) troposphere (Wheeler and Hendon, 2004) has been used for this purpose. The MJO strongly modulates the genesis and intensity of CDs over the north Indian Ocean. However there are other factors contributing to cyclogenesis over the north Indian Ocean, as about 60% of cyclogenesis during monsoon and post-monsoon seasons are not significantly related with MJO. While the probability of cyclogenesis during monsoon season is higher with MJO in phase 4 and 5 (Maritime Continent), that during post-monsoon season is higher with MJO in phase 3 and 4 (east Indian Ocean and adjoining Maritime Continent). It indicates that while possibility of genesis during monsoon season is significantly suppressed with active MJO at phase 1, 7 and 8 (Africa, western Hemisphere and adjoining Pacific Ocean), there is no significant relationship between genesis and active MJO at phase 1, 7 and 8 during post-monsoon season. The anomalous cyclonic circulation at lower levels over central and north Bay of Bengal in association with MJO at phase 4 and 5 favours enhanced probability of cyclogenesis over the Bay of Bengal during monsoon season. The anomalous easterlies in association with MJO at phase 1 and development of anomalous ridge over south India in association with MJO at phase 7 and 8 which are weak monsoon features lead to suppressed cyclogenesis over north Indian Ocean during this season. The anomalous north-south trough in easterlies embedded with cyclonic circulation over the south west/west central Bay of Bengal in association with southerly surge over the region during active MJO in phase 3 and 4 most favourably influences the convection and enhances the probability of cyclogenesis over the north Indian Ocean during post-monsoon season. The genesis of CDs is more sensitive to phase than the amplitude while the intensification of CDs is more dependent on the amplitude of MJO. Comparing monsoon and post-monsoon seasons, the modulation of genesis, intensification and duration of CDs by the MJO is more during the monsoon season than the post-monsoon season.

scholarly journals Analysis of rainfall and temperature trends of selected stations over North East India during last century

MAUSAM ◽  
2021 ◽  
Vol 65 (4) ◽  
pp. 497-508
Author(s):  
S.I. LASKAR ◽  
S.D. KOTAL ◽  
S.K.ROY BHOWMIK
Keyword(s):  
Monsoon Season ◽  
Maximum Temperature ◽  
Rainfall Time Series ◽  
North East India ◽  
Post Monsoon ◽  
North East ◽  
The North ◽  
Increasing Trend ◽  
Post Monsoon Season ◽  
Increasing Trends

In this study, the trends of seasonal maximum and minimum temperatures and rainfall time series were investigated for 9 selected stations in the north eastern India with the available data stretching between the years 1913-2012.During the period under study the minimum temperature has increasing trends in almost all the stations of north east India except Cherrapunji where it shows decreasing trend in all the season of the year. In case of maximum temperature Cherrapunji, Guwahati and Imphal show increasing trends during all the seasons. Agartala and Shillong show increasing trend of maximum temperature during monsoon and post monsoon season. Dibrugarh and Pasighat show decreasing trend during pre monsoon season and increasing trend during all other seasons of the year. Gangtok shows decreasing trend of maximum temperature during all the seasons where as Silchar shows no trend in maximum temperature.Out of all the selected nine stations, most of the stations show either decreasing trend or no trend of rainfall except Guwahati which shows significant increasing trend of rainfall during post monsoon season.

scholarly journals Cyclonic storms and Depressions over the north Indian Ocean during 2019*

MAUSAM ◽  
2021 ◽  
Vol 71 (3) ◽  
pp. 357-376
Author(s):  
Kashyapi A ◽  
Shripad V K ◽  
Natu J C
Keyword(s):  
Arabian Sea ◽  
Monsoon Season ◽  
North Indian Ocean ◽  
Cyclonic Storm ◽  
Post Monsoon ◽  
The North ◽  
Post Monsoon Season ◽  
Severe Cyclonic Storm ◽  
Cyclonic Storms ◽  
Indian Seas

During 2019, in all 12 intense low pressure systems formed over the Indian Seas. These include; one Super cyclonic storm (KYARR), one extremely severe cyclonic storm (FANI), 4 very Severe Cyclonic Storms (VAYU, HIKAA, MAHA & BULBUL), 2 Cyclonic Storms (PABUK & PAWAN), 3 Deep Depressions and  1 Depression. Out of these 12 systems, 4 systems formed over the Bay of Bengal and 8 over the Arabian Sea. Arabian Sea remained exceptionally active in terms of cyclogenesis this year, especially in the post monsoon season. The season-wise distribution had been one cyclonic storm in winter, one in pre-monsoon season,  2 depressions and 2 very severe cyclonic storms during the monsoon season and 4 cyclonic storms and 3 depressions in Post monsoon season.

scholarly journals Tropical cyclone frequency in the north Indian Ocean in relation to southern oscillation phenomenon

MAUSAM ◽  
2022 ◽  
Vol 52 (3) ◽  
pp. 511-514
Author(s):  
O. P. SINGH ◽  
TARIQ MASOOD ALI KHAN ◽  
MD. SAZEDUR RAHMAN
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Southern Oscillation ◽  
North Indian Ocean ◽  
Tropical Cyclone Frequency ◽  
The North ◽  
Cyclone Frequency

The present paper deals with the influence of Southern Oscillation (SO) on the frequency of tropical cyclones in the north Indian Ocean. The results show that during the negative phase of SO the frequency of tropical cyclones and depressions over the Bay of Bengal and the Arabian Sea diminishes in May which is most important pre-monsoon cyclone month. The correlation coefficient between the frequency of cyclones and depressions and the Southern Oscillation Index (SOI) is +0.3 which is significant at 99% level. Post-monsoon cyclone frequency in the Bay of Bengal during November shows a significant positive correlation with SOl implying that it also decreases during the negative phase of SO. Thus there is a reduction in the tropical cyclone frequency over the Bay of Bengal during both intense cyclone months May and November in EI-Nino/Southern Oscillation (ENSO) epochs. Therefore it would not be correct to say that ENSO has no impact on the cyclogenesis in the north Indian Ocean. It is true that ENSO has no significant impact on the frequency of cyclones in the Arabian Sea. ENSO also seems to affect the rate of intensification of depressions to cyclone stage. The rate of intensification increases in May and diminishes in November in the north Indian Ocean during ENSO. The results are based on the analysis of monthly frequencies of tropical cyclones and depressions and SOI for the 100 year period from 1891-1990.

Extended Prediction of North Indian Ocean Tropical Cyclones

2012 ◽  
Vol 27 (3) ◽  
pp. 757-769 ◽  
Author(s):  
James I. Belanger ◽  
Peter J. Webster ◽  
Judith A. Curry ◽  
Mark T. Jelinek
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
North Indian Ocean ◽  
Ensemble Prediction ◽  
Tropical Cyclone Genesis ◽  
Lead Times ◽  
Prediction System ◽  
Ensemble Prediction System ◽  
The North

Abstract This analysis examines the predictability of several key forecasting parameters using the ECMWF Variable Ensemble Prediction System (VarEPS) for tropical cyclones (TCs) in the North Indian Ocean (NIO) including tropical cyclone genesis, pregenesis and postgenesis track and intensity projections, and regional outlooks of tropical cyclone activity for the Arabian Sea and the Bay of Bengal. Based on the evaluation period from 2007 to 2010, the VarEPS TC genesis forecasts demonstrate low false-alarm rates and moderate to high probabilities of detection for lead times of 1–7 days. In addition, VarEPS pregenesis track forecasts on average perform better than VarEPS postgenesis forecasts through 120 h and feature a total track error growth of 41 n mi day−1. VarEPS provides superior postgenesis track forecasts for lead times greater than 12 h compared to other models, including the Met Office global model (UKMET), the Navy Operational Global Atmospheric Prediction System (NOGAPS), and the Global Forecasting System (GFS), and slightly lower track errors than the Joint Typhoon Warning Center. This paper concludes with a discussion of how VarEPS can provide much of this extended predictability within a probabilistic framework for the region.

scholarly journals Pacific Decadal Oscillation Causes Fewer Near-Equatorial Cyclones in North Indian Ocean

2021 ◽  
Author(s):  
Shinto Roose ◽  
Ajayamohan Ravindran ◽  
Pallav Ray ◽  
Shang-Ping Xie ◽  
Cherumadanakadan Thelliyil Sabeerali ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Tropical Cyclones ◽  
Pacific Decadal Oscillation ◽  
North Indian Ocean ◽  
Mitigation Strategies ◽  
The Past ◽  
The North ◽  
The Pacific ◽  
Low Latitudes ◽  
Cyclone Frequency

Abstract Tropical cyclones do not form easily near the equator but can intensify rapidly, leaving little time for preparation. We investigated the number of near-equatorial (originating between 5°N and 11°N) tropical cyclones over the north Indian Ocean during post-monsoon seasons (October to December) over the past 60 years. A marked 43% decline in the number of such cyclones was detected in recent decades (1981-2010) compared to earlier (1951-1980). This decline in tropical cyclone frequency is primarily due to the weakened low-level vorticity modulated by the Pacific Decadal Oscillation (PDO). In the presence of basin-wide warming at low latitudes, and a favorable phase of the PDO, both the intensity and frequency of such cyclones is expected to increase. Such dramatic and unique changes in tropical cyclonic activity due to the interplay between natural variability and climate change call for appropriate planning and mitigation strategies.

scholarly journals The relationship between geopotential height and movement & landfall of tropical cyclone in the Bay of Bengal region

MAUSAM ◽  
2022 ◽  
Vol 63 (3) ◽  
pp. 469-474
Author(s):  
G.K. DAS ◽  
S.K. MIDYA ◽  
G.C. DEBNATH ◽  
S.N. ROY
Keyword(s):  
Tropical Cyclone ◽  
Bay Of Bengal ◽  
Geopotential Height ◽  
Monsoon Season ◽  
Simple Relationship ◽  
Post Monsoon ◽  
Post Monsoon Season ◽  
The Relationship

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.

scholarly journals Trends and fluctuations of the cyclonic systems over North Indian Ocean

MAUSAM ◽  
2021 ◽  
Vol 52 (1) ◽  
pp. 37-46
Author(s):  
D. V. BHASKAR RAO ◽  
C. V. NAIDU ◽  
B. R. SRINIVASA RAO
Keyword(s):  
Time Series ◽  
Indian Ocean ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
North Indian Ocean ◽  
Pass Filter ◽  
Long Term Trends ◽  
High Pass ◽  
Cyclone Frequency

The data of the monthly cyclone frequencies over North Indian Ocean for the period 1877-1998 has been analysed to study the long-term trends and fluctuations. Analysis has been made separately for depressions and cyclones for the pre-monsoon, monsoon and post-monsoon seasons along with the annual frequencies. The data was subjected to 11-year moving averages and the epochs of increasing and decreasing trends have been identified. A consistent decreasing trend after 1950s is a notable feature.   The time series of the monthly cyclone frequency were passed through a high-pass filter to eliminate periods greater than 21 years and then subjected to spectrum analysis using Maximum Entropy Method to obtain dominant periodicities. Three significant periodicities at 2.2-2.8; 3.5-6.5 and 10-15 years have been identified which could be attributed to QBO, ENSO and decadal frequencies.

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