scholarly journals Intensification and movement of cyclonic storm in the Bay of Bengal during post monsoon season

MAUSAM ◽  
2021 ◽  
Vol 59 (1) ◽  
pp. 51-68
Author(s):  
A. MUTHUCHAMI ◽  
S. SRIDHARAN
Keyword(s):  
Relative Humidity ◽  
Bay Of Bengal ◽  
Wind Shear ◽  
Monsoon Season ◽  
India Meteorological Department ◽  
Reanalysis Data ◽  
Cyclonic Storm ◽  
Post Monsoon ◽  
Post Monsoon Season ◽  
Cyclonic Storms

Using NCEP/NCAR reanalysis data and from the available data on tracks of the storms from India Meteorological Department for the period 1981-2005 an attempt is made to understand the intensification of storms and their movements in the Bay of Bengal during post-monsoon season. It is noticed that in the month of October only 12 % of the cyclonic storms weakened whereas in November and December it is 28 % and 41 % respectively. Cyclonic storms moving in a northeast direction weaken in all the months of post-monsoon season. Most of the westward moving storms do not undergo weakening. In the Bay of Bengal, SST and relative humidity are not responsible for weakening of the storms except in December but wind shear is responsible for weakening. The orientation of isotherms of SST of Bay of Bengal influences the direction of motion.  During the years when the storms are predominantly moving west/northwest the SST over the Bay of Bengal is about 1.0° C warmer than the years when the storms are predominantly moving in north/northeastward. If the isotherms of SST are oriented southwest-northeast with higher value in the east then system may move in north or northeastward and on such occasions east Bay of Bengal is warmer than west Bay of Bengal.

scholarly journals Seasonal Variation of Tropical Cyclone Genesis and the Related Large-Scale Environments: Comparison between the Bay of Bengal and Arabian Sea Sub-Basins

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1593
Author(s):  
Wei Duan ◽  
Junpeng Yuan ◽  
Xu Duan ◽  
Dian Feng
Keyword(s):  
Tropical Cyclone ◽  
Relative Humidity ◽  
Wind Shear ◽  
Monsoon Season ◽  
Vertical Wind Shear ◽  
Vertical Wind ◽  
Tropical Cyclone Genesis ◽  
Positive Contribution ◽  
Post Monsoon ◽  
Post Monsoon Season

Using tropical cyclone data along with sea surface temperature data (SST) and atmospheric circulation reanalysis data during the period of 1980–2019, the seasonal variation of tropical cyclone genesis (TCG), and the related oceanic and atmospheric environments over the Arabian Sea (AS) and Bay of Bengal (BOB) are compared and analyzed in detail. The results show that TCG in both the BOB and AS present bimodal seasonal variations, with two peak periods in the pre-monsoon and post-monsoon season, respectively. The frequencies of TCG in the BOB and AS are comparatively similar in the pre-monsoon season but significantly different in the post-monsoon season. During the post-monsoon season of October–November, the TCG frequency in the BOB is approximately 2.3 times higher than that of the AS. The vertical wind shear and relative humidity in the low- and middle-level troposphere are the two major contributing factors for TCG, and the combination of these two factors determines the bimodal seasonal cycle of TCG in both the AS and BOB. In the pre-monsoon season, an increase in the positive contribution of vertical wind shear and a decrease in the negative contribution of relative humidity are collaboratively favorable for TCG in the AS and BOB. During the monsoon season, the relative humidity factor shows a significant and positive contribution to TCG, but its positive effect is offset by the strong negative effect of vertical wind shear and potential intensity, thus resulting in very low TCG in the AS and BOB. However, the specific relative contributions of each environmental factor to the TCG variations in the AS and BOB basins are quite different, especially in the post-monsoon season. In the post-monsoon season, the primary positive contributor to TCG in the AS basin is vertical wind shear, while the combined effect of vertical wind shear and relative humidity dominates in the BOB TCG. From the analysis of environmental factors, atmospheric circulations, and genesis potential index (GPI), the BOB is found to have more favorable TCG conditions than the AS, especially in the post-monsoon season.

scholarly journals Climatology of Energetics of cyclones over Indian Seas

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Somenath Dutta ◽  
Geena Sandhu ◽  
Sanjay G Narkhedkar ◽  
Sunitha Devi
Keyword(s):  
Tropical Cyclones ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Monsoon Season ◽  
Recent Decade ◽  
Reanalysis Data ◽  
Monsoon Period ◽  
Post Monsoon ◽  
Post Monsoon Season ◽  
Indian Seas

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.

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 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.

Evapotranspiration Distribution and Variation of Pakistan (1931-2015)

2017 ◽  
Vol 17 (2) ◽  
pp. 184-197 ◽  
Author(s):  
Saifullah Khan ◽  
Mahmood Ul Hasan
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Surface Pressure ◽  
Sunshine Duration ◽  
Monsoon Season ◽  
Winter Season ◽  
Main Element ◽  
Mountainous Region ◽  
Post Monsoon ◽  
Post Monsoon Season

AbstractEvapotranspiration is the main element of aridity and desertification and to balance the natural hydrological processes. Pakistan has a high degree of evapotranspiration, as it is in subtropical belt, with long sunshine duration and low cloudiness in summers. June is the warmest month, when the evapotranspiration exceeds 7mm (0.28inches), whereas, January is the coldest month, when evapotranspiration of the country falls to 1mm (0.04inches). The maximum evapotranspiration has been recorded at the southern latitudes of the country (Hyderabad and Jacobabad), while it decreases towards northwest (mountainous region) and Gilgit-Baltistan (Astore and Skardu). This variation in evapotranspiration is due to fluctuation in temperature, precipitation, sunshine duration, wind speed, relative humidity, physical relief and latitudinal as well as altitudinal extend of the country. The average evapotranspiration of Pakistan is 4.5mm with an increase of 1.0mm during 1931-2015. In winter and summer season, the lower Indus basin, has recorded high evapotranspiration as compared to the northern mountainous region. The average evapotranspiration of Pakistan during winter season is 2.7mm, while in summer it is 6.3mm. This variation is due to the variation in the length of day and night, humidity, precipitation, surface pressure, wind speed, and topography of the land. During cold season the average evapotranspiration of the country is 13.7mm, pre-monsoon season 17.1mm, monsoon season 15.8mm and post monsoon season 8mm. Obviously, the highest evapotranspiration of Pakistan has recorded during pre-monsoon season with extreme temperature, scarce precipitation, long sunshine duration, lowest relative humidity, low pressure, and calm winds and chilly condition. Furthermore, during cold (0.1mm), pre-monsoon (3.5mm), and monsoon season (2.2mm) the evapotranspiration shows an increase, where as it reveals a negative deviation of -5.6mm in post monsoon season due to increase in the precipitation from reversible monsoon lows at the southern latitudes of the country. Generally, the evapotranspiration of Pakistan increases from northwest to southeast and a main agent of delimitation of the arid region of the country. The main factors that cause variation in the evapotranspiration of the country from south towards north are temperature, precipitation, sunshine duration, relative humidity, surface pressure, wind speed, fogs, cloudiness, topography, latitudinal and altitudinal extend of the country that required further research.

scholarly journals Modulation of environmental conditions on the significant difference in the super cyclone formation rate during the pre- and post-monsoon seasons over the Bay of Bengal

2021 ◽  
Author(s):  
Zhi Li ◽  
Yuhuan Xue ◽  
Yue Fang ◽  
Kuiping Li
Keyword(s):  
Bay Of Bengal ◽  
Monsoon Season ◽  
Formation Rate ◽  
Specific Humidity ◽  
Global Maximum ◽  
Tropical Ocean ◽  
Post Monsoon ◽  
Significant Difference ◽  
Post Monsoon Season ◽  
Upper Level

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.

scholarly journals Intercomparison review of IPWV retrieved from INSAT-3DR sounder, GNSS and CAMS reanalysis data

2021 ◽  
Vol 14 (7) ◽  
pp. 4857-4877
Author(s):  
Ramashray Yadav ◽  
Ram Kumar Giri ◽  
Virendra Singh
Keyword(s):  
Water Vapor ◽  
Monsoon Season ◽  
Winter Season ◽  
Precipitable Water ◽  
Satellite System ◽  
Reanalysis Data ◽  
Regional Variability ◽  
Post Monsoon ◽  
Post Monsoon Season ◽  
Gnss Data

Abstract. The spatiotemporal variations of integrated precipitable water vapor (IPWV) are very important in understanding the regional variability of water vapor. Traditional in situ measurements of IPWV in the Indian region are limited, and therefore the performance of satellite and Copernicus Atmosphere Meteorological Service (CAMS) retrievals with the Indian Global Navigation Satellite System (GNSS) as reference were analyzed. In this study the CAMS reanalysis data of 1 year (2018) and the Indian GNSS and INSAT-3DR sounder retrieval data for 1.5 years (January 2017 to June 2018) were utilized, and statistics were computed. It is noticed that seasonal correlation coefficient (CC) values between INSAT-3DR and Indian GNSS data mainly lie within the range of 0.50 to 0.98 for all the selected 19 stations except Thiruvananthapuram (0.1), Kanyakumari (0.31) and Karaikal (0.15) during the monsoon season and Panjim (0.2) during the post-monsoon season. The seasonal CC values between CAMS and GNSS IPWV range from 0.73 to .99 except for Jaipur (0.16) and Bhubaneswar (0.29) during the pre-monsoon season, Panjim (0.38) during the monsoon season, Nagpur (0.50) during the post-monsoon season, and Dibrugarh (0.49) Jaipur (0.58) and Bhubaneswar (0.16) during the winter season. The root mean square error (RMSE) values are higher under the wet conditions (pre-monsoon and monsoon season) than under dry conditions (post-monsoon and winter season), and we found differences in magnitude and sign of bias for INSAT-3DR and CAMS with respect to GNSS IPWV from station to station and season to season. This study will help to improve understanding and utilization of CAMS and INSAT-3DR data more effectively along with GNSS data over land, coastal and desert locations in terms of the seasonal flow of IPWV, which is an essential integrated variable in forecasting applications.

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