scholarly journals Trends in the frequency of cyclonic disturbances and their intensification over Indian seas

MAUSAM ◽  
2021 ◽  
Vol 51 (2) ◽  
pp. 113-118
Author(s):  
A. K. SRIVASTAVA ◽  
K. C. SINHA RAY ◽  
U. S. DE
Keyword(s):  
Bay Of Bengal ◽  
Arabian Sea ◽  
Hadley Circulation ◽  
Cyclonic Activity ◽  
Recent Period ◽  
Level Of Confidence ◽  
Cyclonic Disturbances ◽  
Indian Seas

Trends in cyclonic disturbances for the period 1891-1997 were studied over Bay of Bengal and Arabian Sea. It is noticed that there is a significant decreasing trend at 99% level of confidence in the frequency of storms. The slopes of decreasing trend in cyclonic activity over Bay of Bengal and that over Arabian Sea were found to be maximum during last four decades. Weakening of Hadley circulation due to upper tropospheric warming may be one of the cause of this decreasing trend. There appears to be decrease in intensification of cyclonic disturbances in recent period.

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 Latitudinal distribution of water vapour over the Arabian Sea and Bay of Bengal using Bhaskara-II SAMIR data

MAUSAM ◽  
2021 ◽  
Vol 43 (4) ◽  
pp. 385-394
Author(s):  
P.N. PATHAK ◽  
N. GAUTAM
Keyword(s):  
Water Vapour ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Latitudinal Gradient ◽  
Southwest Monsoon ◽  
Climatological Data ◽  
Latitude Range ◽  
Uniform Value ◽  
Northern Winter ◽  
Indian Seas

The main purpose of the present work is to establish the reliability of the SAMIR-derived water vapour (WV) data over the Arabian Sea and the Bay of Bengal for the entire 18-month from January 1982 to June 1983 period of the in-orbit operation of the SAMIR system. The average latitudinal distributions of WV over the Arabian Sea and Bay of Bengal for different months, derived from the SAMJR data were found to be broadly consistent with the climatological data on WV from the coastal and island radiosonde stations.   A significant latitudinal gradient in WV has been found during the northern winter months (Dec-Feb) with the highest value of 4-5 gm/cm2 near the equator and thc lowest value of about 2 gm/cm2 at about 20oN over the Indian seas. This gradient gradually decreases during the subsequent months and almost vanishes during the southwest monsoon months (Jun-Sep) when the WV has nearly uniform value of 4-5 gm/cm2 in the entire latitude range from the equator to 20oN over the Indian seas. Finally, it has been found that WV values over the Bay of Bengal are generally higher than those over the Arabian Sea at co-latitudinal positions. The implications of this result are discussed in the light of other considerations.

scholarly journals Simulations of frequency, intensity and tracks of cyclonic disturbances in the Bay of Bengal and the Arabian Sea

MAUSAM ◽  
2021 ◽  
Vol 60 (2) ◽  
pp. 167-174
Author(s):  
O. P. SINGH
Keyword(s):  
Greenhouse Gas ◽  
Bay Of Bengal ◽  
Andhra Pradesh ◽  
Arabian Sea ◽  
Climate Model ◽  
Global Climate ◽  
North Indian Ocean ◽  
Post Monsoon ◽  
Cyclonic Disturbances ◽  
Monsoon Depressions

The paper presents the results of simulation experiments conducted for the assessment of likely changes in the cyclogenesis pattern in the Bay of Bengal (BOB) and the Arabian Sea (AS) resulting from global climate change. Two experiments were performed, namely the ‘control’ (CTL) experiment in which the greenhouse gas concentration in the atmosphere was fixed as per 1990 levels and the ‘greenhouse gas’ (GHG) experiment in which an annual compound increase of 1% from 1990 onwards was introduced. CTL and GHG experiments of 20 years length were performed for the period 2041-2060. The model used is the regional climate model Had RM2 of the Hadley Centre of Climate Prediction and Research, U.K.    The results have brought out some significant changes in the cyclogenesis pattern in the North Indian Ocean (BOB and AS). The most significant likely change is the increase in the frequency of post-monsoon storms in the Bay of Bengal. The experiments show an increase of about 50% in the post-monsoonal cyclogenesis by 2041-2060 as a result of increased greenhouse gas concentrations in the atmosphere. The frequency of monsoon depressions / storms in the BOB is likely to decrease considerably during June-August. Due to varying impacts in different seasons, the annual frequency of cyclonic disturbances may change marginally in the BOB. In the Arabian Sea, however the model has simulated a significant reduction in the frequency which may be halved by the period 2041-2060. The results show intensification of storms during May-June and September-November. The monsoon depressions  during July-August are  likely to become less intense.   In GHG experiment most of the post-monsoon storms have a tendency to strike north Andhra-Orissa coasts whereas in CTL experiment the storms strike coast from Tamilnadu to south Orissa. Thus, the focus of post-monsoon storms in the BOB is likely to shift northwards from Tamilnadu-Andhra Pradesh coast to north Andhra Pradesh-south Orissa coast. Another important simulated change in storm tracks is that more number of pre-monsoon storms in the BOB may have a tendency to recurve north or northeastwards by 2041-2060.

scholarly journals Multiple variability of summer sea surface temperature (SST) and evaporation over the Indian Seas

MAUSAM ◽  
2021 ◽  
Vol 50 (4) ◽  
pp. 355-342
Author(s):  
O. P. SINGH
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Evaporation Rate ◽  
Function Analysis ◽  
Meteorological Data ◽  
North Indian Ocean ◽  
Sea Surface ◽  
Indian Seas

Utilising thirty one years' marine meteorological data from 1961-91 recorded over the north Indian Ocean the sea surface temperature (SST) and evaporation have been obtained for different regions of the Arabian Sea and the Bay of Bengal. The moving pentad averages of SST and evaporation reveal increasing tendencies of both the parameters over the Arabian Sea and that of evaporation over the Bay of Bengal during May. The changes are real and significant as revealed by the trend analysis. The spectral analysis shows that SST has a 2-3 year significant cycle and evaporation rate has a 2-5 year cycle over the Indian Seas. In addition, a significant 15-year cycle is present in the SST over the Bay of Bengal and evaporation rate over the Arabian Sea. Empirical orthogonal function analysis performed on the anomalies of SST and evaporation rate over the Arabian Sea and the Bay of Bengal reveals that the time coefficient of first EOF has an increasing tendency.

Cyclogenesis in the Bay of Bengal and the Arabian Sea

Tellus ◽  
1970 ◽  
Vol 22 (6) ◽  
pp. 716-718
Author(s):  
K. G. Mowla
Keyword(s):  
Bay Of Bengal ◽  
Arabian Sea

scholarly journals Wind-Driven Response of the Northern Indian Ocean to Climate Extremes*

2007 ◽  
Vol 20 (13) ◽  
pp. 2978-2993 ◽  
Author(s):  
Tommy G. Jensen
Keyword(s):  
Indian Ocean ◽  
Ocean Circulation ◽  
Bay Of Bengal ◽  
El Niño ◽  
Arabian Sea ◽  
El Nino ◽  
Ocean Model ◽  
La Niña ◽  
Northern Indian Ocean ◽  
La Nina

Abstract Composites of Florida State University winds (1970–99) for four different climate scenarios are used to force an Indian Ocean model. In addition to the mean climatology, the cases include La Niña, El Niño, and the Indian Ocean dipole (IOD). The differences in upper-ocean water mass exchanges between the Arabian Sea and the Bay of Bengal are investigated and show that, during El Niño and IOD years, the average clockwise Indian Ocean circulation is intensified, while it is weakened during La Niña years. As a consequence, high-salinity water export from the Arabian Sea into the Bay of Bengal is enhanced during El Niño and IOD years, while transport of low-salinity waters from the Bay of Bengal into the Arabian Sea is enhanced during La Niña years. This provides a venue for interannual salinity variations in the northern Indian Ocean.

Seasonal and Interannual Sea Surface Temperature Variability in the Coastal Cities of Arabian Sea and Bay of Bengal

2004 ◽  
Vol 31 (2) ◽  
pp. 549-560 ◽  
Author(s):  
Tariq Masood Ali Khan ◽  
Dewan Abdul Quadir ◽  
Tad S. Murty ◽  
Majajul Alam Sarker
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Temperature Variability ◽  
Sea Surface ◽  
Coastal Cities

scholarly journals Seven year satellite observations of the mean structures and variabilities in the regional aerosol distribution over the oceanic areas around the Indian subcontinent

2005 ◽  
Vol 23 (6) ◽  
pp. 2011-2030 ◽  
Author(s):  
S. K. Nair ◽  
K. Parameswaran ◽  
K. Rajeev
Keyword(s):  
Indian Ocean ◽  
Southern Hemisphere ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Indian Subcontinent ◽  
Monsoon Season ◽  
Dry Season ◽  
Aerosol Transport ◽  
Summer Monsoon Season ◽  
Aerosol Distribution

Abstract. Aerosol distribution over the oceanic regions around the Indian subcontinent and its seasonal and interannual variabilities are studied using the aerosol optical depth (AOD) derived from NOAA-14 and NOAA-16 AVHRR data for the period of November 1995–December 2003. The air-mass types over this region during the Asian summer monsoon season (June–September) are significantly different from those during the Asian dry season (November–April). Hence, the aerosol loading and its properties over these oceanic regions are also distinctly different in these two periods. During the Asian dry season, the Arabian Sea and Bay of Bengal are dominated by the transport of aerosols from Northern Hemispheric landmasses, mainly the Indian subcontinent, Southeast Asia and Arabia. This aerosol transport is rather weak in the early part of the dry season (November–January) compared to that in the later period (February–April). Large-scale transport of mineral dust from Arabia and the production of sea-salt aerosols, due to high surface wind speeds, contribute to the high aerosol loading over the Arabian Sea region during the summer monsoon season. As a result, the monthly mean AOD over the Arabian Sea shows a clear annual cycle with the highest values occurring in July. The AOD over the Bay of Bengal and the Southern Hemisphere Indian Ocean also displays an annual cycle with maxima during March and October, respectively. The amplitude of the annual variation is the largest in coastal Arabia and the least in the Southern Hemisphere Indian Ocean. The interannual variability in AOD is the largest over the Southeast Arabian Sea (seasonal mean AOD varies from 0.19 to 0.42) and the northern Bay of Bengal (seasonal mean AOD varies from 0.24 to 0.39) during the February–April period and is the least over the Southern Hemisphere Indian Ocean. This study also investigates the altitude regions and pathways of dominant aerosol transport by combining the AOD distribution with the atmospheric circulation. Keywords. Atmospheric composition and structure (Aerosols and particles) – Meteorology and atmospheric dynamics (Climatology) – Oceanography: physical (Ocean fog and aerosols)

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