For several hundred years after the Europeans arrived in West Indies, hurricanes were named after the saint’s day on which the storm struck. If a second storm struck on the same saint’s day later, it would be referred to as segundo (Spanish for ‘the second’), such as hurricane San Felipe Segundo. The practice of naming storms after people was introduced by Clement Lindley Wragge, an Anglo-Australian meteorologist, at the end of 19th century. He used female names and names of politicians who had offended him apart from names from history and mythology. The modern convention of systematically naming tropical storms and hurricanes was initiated in 1953 by the United States National Hurricane Centre. From 1979 onwards, female and male names are alternately assigned. Naming is now, however maintained by the World Meteorological Organisation (WMO).
There has been no system of cyclone naming in the North Indian Ocean comprising of Bay of Bengal and Arabian Sea until recently. Eight countries of the region – India, Bangladesh, Myanmar, Thailand, Sri Lanka, Pakistan, Maldives and Oman are part of a regional entity called ‘WMO ESCAP Panel’. In 2004 the countries agreed that terms that depict nature – such as agni, akash, vayu, lehar, sagar, etc., or names that do not allude to gods or goddesses of any faith, such as Nisha, Nargis, Priya, etc., could be assigned to cyclones. As per agreed arrangement, all countries were expected to provide a list of names which would be clubbed together and listed alphabetically country wise. Depending on the genesis of cyclones, the names would be picked up from the list. Nargis was a name from Pakistan. Subsequent cyclones in the region will be named Abe (Srilanka), Khai Muk (Thailand), Nisha (Bangladesh) and Bijili (India).
Anatomy of Nargis
Nargis was born as a low pressure system over southeast Bay of Bengal in the morning of 26th April, 2008. It intensified over an area where it found favourable conditions like warmer sea surface temperature, low vertical wind shear and poleward outflow. By 27th Nargis was a deep depression. The system was initially propelled westward but under the influence of a steering (wind) flow from the southeast, it started moving in a northwesterly direction. It intensified into a cyclonic storm by 28th, further intensified into a severe cyclonic storm and then into very severe cyclonic storm by 29th. As the system came under the influence of easterly winds it began to move in east-northeast on 1st May and then eastward registering further intensification before it crossed southwest coast of Myanmar close to capital city of Yangon, between 12 to 14 GMT of 2nd May. After crossing the coast, it took northeasterly course. Interestingly, even after crossing the coast, the system maintained its intensity of a very severe cyclonic storm until 3rd morning and gradually weakened thereafter. Nargis had an associated surface wind of 170 kmph which caused the storm surge (sea waves) to rise to a height of about 4 meters. Widespread rainfall caused floods in Ayeyarwady Delta and Yangon. Nargis has been one of the deadliest cyclones of the region in recent times after April 1991 cyclone of Bangladesh which killed 1,32,000 people. Although official figure of deaths caused by Nargis has been over 78,000 with 55,000 missing, unofficial figures of death may be well over a lakh.
Indian cyclones the deadliest
Tropical cyclones are considered one of nature’s most violent manifestations and potentially deadliest of all meteorological phenomena. It is a unique combination of violent winds, heavy rainfall and storm surges. Of all regions, Indian sub-continent is the worst affected with the death toll being highest in the globe. Records of past two centuries indicate that 21 out of 23 major cyclones with associated human deaths of over 10,000, have occurred in the Indian subcontinent. The propensity of devastating consequences is attributed to three factors –
- Shallow bathymetry of continental shelf (gentle slope of coastal region which propels greater heights in storm surges. About 90 percent of deaths are caused by storm surges);
- High population density and poor economic conditions in the coastal areas of India and Bangladesh; and
- Reluctance of people in coastal regions to vacate under a cyclonic threat.
Interestingly, cyclone frequency in the Indian region is one of the lowest in the world. Only 5 percent of the total global cyclone genesis takes place in the Indian seas.
India is first
India is one of first countries in the world to set up a tropical cyclone warning system. Way back in 1864, a disastrous tropical cyclone struck Bengal killing over 60,000 people. Soon after, the colonial rulers established a cyclone warning system for the country. In fact, the cyclone warning system was the progenitor of the India Meteorological Department (IMD) which was established in 1875 – a decade later. The Asiatic Society of Bengal founded in 1784 at Calcutta, promoted scientific studies in meteorology in India. The word ‘cyclone’ has been gifted by India to the world. Captain Henry Piddington, a scientist working in the Society coined the word signifying a coil of a snake. In 1842 he published his monumental work on the ‘Laws of the Storms’, which is one of the oldest citations in the world.
Cyclone warning which occupied a place of pride among the meteorological services in India underwent continuous and substantial improvements as days passed. But, at the core of these improvements were scientific and technological interventions. Recognising this and our strategic position in the region, the WMO during early nineties designated IMD Delhi as one of the five Regional Specialised Meteorological Centres (RSMCs) of the world for tropical cyclones. India has been given responsibility to provide cyclone advisories to all the countries bordering Bay of Bengal and Arabian Sea.
Cyclone warning system
As the RSMC is mandated to provide cyclone advisories to the WMO ESCAP Panel Region, it fulfilled its commitment and followed the Nargis track with complete accuracy. The WMO appreciated Delhi RSMC’s real time services towards providing cyclone warnings to Myanmar which helped initiate necessary action for disaster management.
There are four major components of early warning system on tropical cyclone
- Risk identification;
- Observing and forecast system;
- Communication and dissemination; and
- Emergency planning, preparedness and response.
The steps are sequential- the last two actions can’t be initiated unless first two are made available to disaster managers. The accuracy and timeliness of the meteorological observations and forecasts are therefore critical to effective disaster management.
The IMD has recently launched a modernisation plan for setting up advanced observing system for tropical cyclones and other disasters. Plans are afoot to set up a close network of Doppler weather radars to cover entire east and west coasts to detect the dynamics of each cyclone. A close network of cyclone proof satellite based automatic weather stations is also being established. As India never had an exclusive cyclone prediction model, an Indo-US collaborating programme is underway to implement a Hurricane Weather Research Forecast (H-WRF) model for cyclone prediction. Countries like US, Japan, Australia etc., have tropical cyclone probing programmes wherein instrumented aircraft are being used to take observations of the cyclones. India has been lagging behind in this area. Ministry of Earth Sciences in collaboration with the USA and several institutions in the country are launching a Forecast Demonstration Project on cyclone probing. Taking a cue from the US experience, this is expected to bring a quantum jump in our capability to provide most accurate predictions on tropical cyclones.