Collaborative Mechanism for Tropical Cyclone Monitoring and Prediction over North Indian Ocean
Tropical Cyclones (TCs) are intense synoptic scale weather systems which originate over warm oceans of the world, develop into massive vortices composed of swirling winds, intense clouds and torrential rains by drawing energy from the ocean. When they mov
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1 Introduction Tropical Cyclones (TCs) are intense synoptic scale weather systems which originate over warm oceans of the world, develop into massive vortices composed of swirling winds, intense clouds and torrential rains by drawing energy from the ocean. When they move over land, they cause large scale destruction to life and property over the coastal areas of the world. India, with an extensive coastline of about 7500 km is vulnerable to the destructive features associated with landfalling TCs of the North Indian Ocean (NIO) basin comprising of the Bay of Be ngal (BOB) and the Arabian Sea (AS). Generally, under favourable environmental conditions, a pre-existing low pressure area develops into a cyclonic disturbance (CD) (maximum sustained wind speed (MSW) of 17 knots or more) which intensifies into a TC (MSW: 34 knots or more) or a severe TC (MSW of 48 knots or more) or even a very severe TC (MSW of 64 knots or more). On an average, about 11 CDs develop over the NIO during a year including 9 and 2 over the BOB and AS (Mohapatra et al. 2014). Out of these, about five intensify into TC (4 over BOB and 1 over the AS), 3 into severe TC (2 over the BOB and 1 over the AS) and 1–2 into very severe TC. Low lying coastal belts of West Bengal, Odisha and Andhra Pradesh have borne the brunt of the fury of these very severe TCs (IMD 2002; Mohapatra et al. 2012a; Mohapatra and Sharma 2015). Adverse impact of destructive TCs in the past over Indian coasts emphasized the need for a storm warning service in the country. As an effort towards mitigating the disastrous effects of landfalling TCs, the Government of India appointed a committee in 1865 to formulate a scheme for TC warning and based on the recommendations of the committee, the first storm warning centre in
L.S. Rathore (*) • M. Mohapatra • B. Geetha India Meteorological Department, Mausam Bhawan, Lodi Road, 110003 New Delhi, India e-mail: [email protected] © Capital Publishing Company 2017 M. Mohapatra et al. (eds.), Tropical Cyclone Activity over the North Indian Ocean, DOI 10.1007/978-3-319-40576-6_1
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India was established at Kolkata in 1865 (Mohapatra et al. 2012b). Subsequently, India Meteorological Department (IMD), the National Weather Service of India was established in 1875 and the important mandate of monitoring and forecasting of TCs over the NIO was vested with it. Since then, IMD is involved in detection, tracking and forecasting the movement and intensity of TCs over the NIO, which has been a highly challenging task during the early years with data sparse sea areas of BOB and AS. Further, the following few peculiarities of the NIO basin added to the challenging task: 1. Though TCs are in general seasonal phenomena, with most tropical ocean basins having maximum frequency of formation during the late summer to early autumn period, TC frequency over the NIO shows bimodal character with primary peak during the post-monsoon season (October to December) followed by the secondary peak during the pre-monsoon season (March to May
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