Extended Range Tropical Cyclone Predictions for East Coast of India - Monitoring and Prediction of Tropical Cyclones in the Indian Ocean and Climate Change - page 133

Extended Range Tropical Cyclone
Predictions for East Coast of India
M. Rajasekhar*, C.M. Kishtawal 1 , M.Y.S. Prasad 2 ,
V. Seshagiri Rao 2 and M. Rajeevan 3
Meteorology Facility, Range Operations, Sathish Dhawan Space
Centre (SDSC SHAR), Indian Space Research Organization
(ISRO), Sriharikota, India
1 Atmospheric Sciences Division, Meteorology and Oceanography
Group, Space Applications Centre (ISRO), Ahmedabad, India
2 SDSC SHAR (ISRO) , Sriharikota, India
3 Ministry of Earth Sciences (MoES), New Delhi, India
*e-mail: [e-mail]
1. Introduction
East Coast of India is vulnerable for tropical cyclone hazards which form over
Bay of Bengal (BoB). The average annual frequency of tropical cyclones over
the BoB and Arabian Sea (AS) is about five (about 5-6% of the global annual
average) and about 80 cyclones form around the globe in a year. The frequency
is more in the BoB than in the Arabian Sea, the ratio being 4:1. The monthly
frequency of tropical cyclones in the north Indian Ocean display a bi-modal
characteristic with a primary peak in November and secondary peak in May.
The months of April-May and October-December are known to produce
cyclones of severe intensity. Tropical cyclones developing during the monsoon
months (June to September) are generally not so intense . Though considered to
be much weaker in intensity and smaller in size as compared to the cyclones of
other regions, the BoB storms are exceptionally devastating, especially when
they cross the land (I.M.D., 1979, 1996). This is mainly due to shallow
bathymetry, nearly funnel shape of the coastline, and the long stretch of the
low-lying delta region entrenched with large number of river systems leading
to high storm surges and coastal inundations (Das, 1974; Dube, 1997).
Tropical cyclogenesis has been a popular atmospheric science research
topic in the past few decades, but it remains the least understood phase of the
tropical cyclone life cycle (Emanuel, 2005). There are some well-accepted