Development and Rapid Intensification of Tropical Cyclone OCKHI (2017) over the North Indian Ocean

2020 ◽  
Vol 3 (3) ◽  
Author(s):  
Geetha B ◽  
Balachandran S
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
North Indian Ocean ◽  
Vertical Shear ◽  
Rapid Intensification ◽  
Initial Development ◽  
Structural Mechanism ◽  
The North ◽  
Mature Phase ◽  
South Indian

Tropical Cyclone OCKHI over the North Indian Ocean during 2017 underwent dramatic development and rapid intensification very close to the land - Sri Lanka, extreme South Indian coast and Lakshadweep area during its initial developmental stage and caused extensive damages over these areas. On examining the physical and structural mechanism involved in such development, it is observed that the initial development was associated with axi-symmetrisation of the vortex that could be associated with Vortex Rossby waves near the eyewall. Associated with the expulsion of high vorticity from the centre during asymmetry mixing, there was outward propagation of eddy angular momentum flux in the lower levels that strengthened a low level anticyclone to the northeast of the TC centre which in turn enhanced the cyclonic inflow near the TC centre. The rapid intensification phase was associated with vertical non-uniform heating with upper and lower tropospheric warming associated with latent heat release in convection.  During the mature phase, the system sustained ‘very severe’ intensity even under increasing vertical shear and lower ocean heat flux under the influence of a break in the sub tropical ridge to the north of the system centre that enhanced the poleward outflow in the upper troposphere.

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 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.

Trend Analysis with a New Global Record of Tropical Cyclone Intensity

2013 ◽  
Vol 26 (24) ◽  
pp. 9960-9976 ◽  
Author(s):  
James P. Kossin ◽  
Timothy L. Olander ◽  
Kenneth R. Knapp
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
Satellite Data ◽  
Formal Analysis ◽  
P Value ◽  
Tropical Cyclone Intensity ◽  
The South ◽  
Cyclone Intensity ◽  
The North ◽  
South Indian

Abstract The historical global “best track” records of tropical cyclones extend back to the mid-nineteenth century in some regions, but formal analysis of these records is encumbered by temporal heterogeneities in the data. This is particularly problematic when attempting to detect trends in tropical cyclone metrics that may be attributable to climate change. Here the authors apply a state-of-the-art automated algorithm to a globally homogenized satellite data record to create a more temporally consistent record of tropical cyclone intensity within the period 1982–2009, and utilize this record to investigate the robustness of trends found in the best-track data. In particular, the lifetime maximum intensity (LMI) achieved by each reported storm is calculated and the frequency distribution of LMI is tested for changes over this period. To address the unique issues in regions around the Indian Ocean, which result from a discontinuity introduced into the satellite data in 1998, a direct homogenization procedure is applied in which post-1998 data are degraded to pre-1998 standards. This additional homogenization step is found to measurably reduce LMI trends, but the global trends in the LMI of the strongest storms remain positive, with amplitudes of around +1 m s−1 decade−1 and p value = 0.1. Regional trends, in m s−1 decade−1, vary from −2 (p = 0.03) in the western North Pacific, +1.7 (p = 0.06) in the south Indian Ocean, +2.5 (p = 0.09) in the South Pacific, to +8 (p < 0.001) in the North Atlantic.

The phosphate levels of the major surface currents of the Indian Ocean

1967 ◽  
Vol 18 (1) ◽  
pp. 1 ◽  
Author(s):  
DJ Rochford
Keyword(s):  
Indian Ocean ◽  
High Salinity ◽  
Average Rate ◽  
North Indian Ocean ◽  
Surface Currents ◽  
The South ◽  
South Indian Ocean ◽  
The North ◽  
South Indian ◽  
South West Monsoon

The principal surface currents of the north Indian Ocean are much richer in phosphate (greater than 0.25 �g-atom/l) than those of the south Indian Ocean (less than 0.15 �g-atom/I). In summer large areas of the surface waters of the south-east Indian Ocean have a very low phosphate content (less than 0.10 �g-atom/l). These waters are by far the lowest in phosphate of the whole Indian Ocean. Their salinity-temperature- phosphate relations show that waters from two regions, the South Equatorial Current in the north and the high salinity belt around 30-35� S., contribute to their formation. Waters of this high salinity belt are carried northward into the low phosphate region by the West Australian Current in summer. These high-salinity waters most probably form by evaporation of an upper 50-m mixed layer of waters of the south-east Atlantic drifting eastward in the south Indian Ocean at an average rate of 15 cm per sec. In the eastern Indian Ocean north of 10�S., surface phosphate levels in summer are governed by the circulation of the richer phosphate waters of the counter current. In winter the circulation of richer phosphate waters of the South-west Monsoon Current governs the phosphate level.

A Tropical Cyclone Analog Program for the North Indian Ocean

1975 ◽  
Vol 103 (3) ◽  
pp. 258-261
Author(s):  
Samson Brand ◽  
James M. Long ◽  
Jack W. Blelloch ◽  
Glenn D. Hamilton
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
North Indian Ocean ◽  
The North

scholarly journals Recent emergence of CAT5 tropical cyclones in the South Indian Ocean

2018 ◽  
Vol 114 (11/12) ◽  
Author(s):  
Jennifer M. Fitchett
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
Satellite Imagery ◽  
Storm Damage ◽  
The South ◽  
South Indian Ocean ◽  
The North ◽  
South Indian ◽  
Recent Emergence

The IBTrACS global best track data set endorsed by the World Meteorological Organization provides a valuable global record of tropical cyclone genesis, track and intensity, and spans 1842 to the present. The record is significantly more robust from the late 1970s onwards, as it is supported by satellite imagery. These records indicate that the first tropical cyclone in the South Indian Ocean to intensify to CAT5 status did so in 1994. This date is significantly later than the first CAT5 storms recorded in the IBTrACS database for the Atlantic Ocean (1924) and the North Pacific (1951) recorded from ship records, and half a decade later than those of the North Indian Ocean (1989) and South Pacific (1988), captured from satellite imagery. Following this late emergence, in the period 1990–2000, eight CAT5 tropical cyclones were recorded for the South Indian Ocean. A further four have been recorded for the period 2010–2015. This recent emergence of tropical cyclones attaining category five intensity in the South Indian Ocean is of significance for the forecasting of tropical cyclone landfall and the anticipation of storm damage for the developing economies that characterise the region. Although an increase in tropical cyclone intensity is frequently projected under global climate change scenarios, the dynamics for the South Indian Ocean have remained poorly understood. Notable are early results indicating an increased frequency and poleward migration of these CAT5 storms, concurrent with a poleward migration in the position of the 26.5 °C, 28 °C and 29 °C sea surface temperature isotherms in the South Indian Ocean. Significance: Category 5 tropical cyclones, the strongest category of storms, have only recently emerged in the South Indian Ocean. Since 1989, their frequency of occurrence has increased. This increase poses a heightened risk of storm damage for the South Indian Ocean Island States and the countries of the southern African subcontinent as a result of the strong winds, heavy rainfall and storm surges associated with these storms, and the large radial extent at category 5 strength.

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