Context: Over the past few years, Scientists have observed the increasing trend of intense cyclonic storms over Arabian Sea.
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- India has a coastline of around 7,516 km of which 5,400 km is alongside the mainland.
- Around 76 percent of India’s coastline is susceptible to cyclones and tsunamis.
- Although the north Indian Ocean engenders merely about 10 per cent of the world’s total cyclones, their effect is tremendous and devastating.
- An analysis of the frequencies of the cyclones suggests that during the period 1891-2000, nearly 308 tropical cyclones crossed the east coast, of which 103 were severe in intensity. Of the 48 cyclones that crossed the west coast, 24 were severe.
- Arabian Sea usually sees a single cyclone every year, but over the last few years, it recorded many cyclones.
- The recent case is of Cyclone ‘Tauktae’, which is very likely to intensify into a severe Cyclonic Storm and may bringing heavy to very heavy rain to many parts of the western coast.
More Cyclones in West Coast
- Arabian Sea is comparatively less prone to cyclonic storms than the Bay of Bengal.
- Here, almost 50 percent of the storms do not sustain over its waters because the west-central and north Arabian Sea have a colder sea temperature than other adjacent regions.
- This cold sea surface temperature is not favourable for the development and sustenance of cyclonic storms.
- However, in last few years, there was an occurrence of one extremely severe cyclone in every four-five years in the Arabian.
- Climatological data from the last few years suggest that the Arabian Sea (west coast) also started receiving tropical cyclones of high intensity in a small time interval.
- From 1998 to 2013 five extremely severe cyclones originated in the Sea.
- In 2014, the west coast of India saw an extremely severe cyclonic storm, ‘Nilofar’ (Category 4).
- In 2015, within one week, the Arabian Sea experienced two more cyclones, even stronger than Nilofar: Cyclone ‘Chapal’ followed by Cyclone ‘Megh’.
- In 2018-19, within a year, Western Coast faced 5 cyclones, Cyclone Nisarga being the 'Severe cyclone'.
- As per India Meteorological Department, in year 2019, the frequency and intensity of cyclonic activity in the Arabian Sea was the highest it had been in over a century.
What's causing the strange activity?
- As per scientists, rising sea surface temperatures (SST) in the Arabian Sea are contributing to the formation of an increased number of cyclones.
- In a 2019 report, the Indian Meteorological Department noted that the SST in the Arabian Sea rose by a staggering 0.36 degrees Celsius, compared with the baselines temperatures between 1981 and 2010.
- Ocean heat, among other various factors, increases the chances of cyclone formation.
- The warmer the ocean, the higher is the probability of more cyclones forming.
- The rising temperature is also one of the factors that have increased the intensity of the cyclones forming.
- Contrasting phenomena: Some studies asserted that the two seas, the Arabian Sea and the Bay of Bengal are experiencing contrasting phenomena.
- While the Arabian Sea has been heating up, the fresh water discharge from the Himalayan glaciers, along with other factors, has had a cooling effect on the Bay of Bengal.
- El Nino Modoki (a climate phenomenon also called ‘pseudo El Nino’) creates conditions which are not conducive for cyclogenesis in the Bay of Bengal.
- It also offers large convergence over the Arabian Sea, explaining a large number of cyclones in that region.
How Cyclones are given names?
- Cyclones are named by the regional specialised meteorological centres (RSMCs) and Tropical Cyclone Warning Centres (TCWCs).
- There are six RSMCs in the world, including the India Meteorological Department (IMD), and five TCWCs.
- It was WMO/ESCAP (World Meteorological Organisation/United Nations Economic and Social Commission for Asia and the Pacific) that decided to start naming cyclones in the region.
- WMO/ESCAP comprises Bangladesh, India, the Maldives, Myanmar, Oman, Pakistan, Sri Lanka and Thailand.
- The guidelines to adopt names: Guidelines are mentioned below on the basis of which the name is accepted by the panel on tropical cyclones (PTC) that finalises the selection:
- The proposed name should be neutral to (1) politics and political figures (2) religious believes, (3) cultures and (4) gender
- Name should be chosen in such a way that it does not hurt the sentiments of any group of population over the globe
- It should not be very rude and cruel in nature
- It should be short, easy to pronounce and should not be offensive to any member
- The maximum length of the name will be eight letters
- The proposed name should be provided with its pronunciation and voice over
- The names of tropical cyclones over the north Indian Ocean will not be repeated.
- Being an RSMC, the IMD names the cyclones developing over the north Indian Ocean, including the Bay of Bengal and Arabian Sea, after following a standard procedure.
- The name of a tropical cyclone from South China Sea which crosses Thailand and emerge into the Bay of Bengal as a tropical cyclone will not be changed.
Indian Meteorological Department (IMD)
- It is the National Meteorological Service of the country which was established in 1875.
- It is under Ministry of Earth Sciences.
- It is the principal government agency in all matters relating to meteorology, seismology and allied subjects.
National Cyclone Risk Mitigation Project (NCRMP)
- It was started to address cyclone risks in the country.
- Its main objective is to reduce the vulnerability of coastal communities to cyclone and other hydro-meteorological hazards through improved early warning dissemination systems and enhanced capacity of local communities to respond to disasters.
Source: Times Now