El Nino Occurrences of over 400 Years

  • A study has tracked El Niño occurrences of over 400 years.
  • The El Niño trends of the past have been studied on the basis of coral cores spanning the Pacific Ocean.
  • Coral cores — like tree rings and ice cores — have centuries-long growth patterns and contain isotopes that can tell us a lot about the climate of the past.
  • El Niños are linked to extreme weather across the globe, with particularly profound effects on precipitation and temperature extremes in Australia, South East Asia and the Americas.
  • Hence, the study is expected to strengthen the science of predicting extreme weathers and plan better.

Finding of the Study

  • El Niños have become stronger and their pattern too has been changing.
  • The trend of El Niño in the last four centuries shows a variation in El Niño types.
  • There has been an increase in central Pacific events (El Niño Modoki) lately.
  • The most recent 30-year period includes fewer, but more intense, eastern Pacific El Niño events.

Madden-Julian Oscillation (MJO)

  • MJO is an eastward moving pulse of cloud & rainfall in the tropics that recurs every 30 to 60 days.
  • Unlike ENSO, which is stationary (in Pacific Ocean), the MJO is an eastward moving disturbance.
  • ENSO is associated with persistent features that last several seasons over the Pacific Ocean basin.
  • On the other hand, multiple MJO events occur within a season (i.e. weather varies on a week-to-week basis).
  • The MJO consists of enhanced rainfall convective phase and suppressed rainfall convective phase.
  • These two phases produce opposite changes in rainfall and this entire dipole propagates eastward.

Madden-Julian Oscillation impact on Weather

  • The MJO can modulate the timing and strength of monsoons.
  • The MJO can influence tropical cyclone numbers and strength in nearly all ocean basins.

The MJO can result in jet stream changes that can lead to cold air outbreaks, extreme heat events, and flooding rains over North America

Cyclone Fani

Cyclone Fani has left a trail of destruction across a large part of coastal Odisha ,but its management has emerged as a Cyclone Faniglobal example of how timely weather alerts,  preparedness and informed public participation can dramatically reduce loss of life.

The toll from the extremely severe cyclonic storm on May 3 , 2019 stood, at last count, at 34 deaths. In terms of material losses, several districts were battered, houses flattened and electricity and telecommunications infrastructure destroyed, but the relatively low mortality shows a dramatic transformation from the loss of over 10,000 lives in 1999 when super cyclone 05B struck. Odisha then worked to upgrade its preparedness, which was tested when very severe cyclonic storm Phailin struck in 2013. It was able to bring down the number of deaths to 44 then, in spite of a wide arc of destruction: 13 million people were hit and half a million houses destroyed. The Odisha government and the Centre now have the task of rebuilding infrastructure. They should use the opportunity to upgrade technology, achieve cost efficiencies and build resilience to extreme weather, all of which can minimise future losses. Given the vulnerability of Odisha and Andhra Pradesh to cyclones, the frequency and intensity of which may be influenced by a changing climate, the center should press for global environmental funding under the UN framework to help in the rebuilding. Both States have received funding from the World Bank in cyclone risk mitigation efforts since 2011.

Cyclones in India

India is highly vulnerable to natural hazards especially earthquakes, floods, drought, cyclones and landslides. Studies indicate that natural disaster losses equate to up to 2% of India Gross Domestic Product (GDP) and up to 12% of Central government revenue. The cyclones that occur between Tropics of Cancer and Capricorn are known as Tropical Cyclones. Tropical cyclones are weather systems in which winds equal or exceed gale force (minimum of 34 knot, i.e., 62 kmph). Indian sub-continent is the worst affected region of the world, having a coastline of 7516 kms. (5400 kms along the mainland, 132 kms in Lakshadweep and 1900 kms in Andaman and Nicobar Islands) is exposed to nearly 10% of the world.Tropical Cyclones. There are 13 coastal states/UTs encompassing 84 coastal districts which are affected by cyclones Four States (Andhra Pradesh , Odisha, Tamil Nadu and West Bengal) and one UT ( Pondicherry ) on the East Coast and One State (Gujarat) on the West Coast are more vulnerable to cyclone disasters. 40% of the total population lives within 100 km of coastline. Cyclones occur in the month of May-June and October-November, with primary peak in November and secondary peak in May. Although cyclones affect the entire coast of India the East Coast is more prone compared to the West Coast. Recurring cyclones account for large number of deaths, loss of livelihood opportunities, loss of public and private property and severe damage to infrastructure, thus seriously reversing the developmental gains at regular intervals. Climate change and its resultant sea-level rises can significantly increase the vulnerability of coastal population.

Classification of tropical Cyclone

The criteria followed by Meteorological Department of India (IMD) to classify the low pressure systems in the Bay of Bengal and in the Arabian Sea as adopted by World Meteorological Organisation (WMO) are as under:

Type of Disturbances Associated Wind Speed in the Circulation
Low pressure Area Less than17 knots (<31 kmph)
Depression 17 to 27 knots (31 to 49 kmph)
Deep Depression 28 to 33 knots (50 to 61 kmph)
Cyclonic Storm 34 to 47 knots (62 to 88 kmph)
Severe Cyclonic Storm 48 to 63 knots (89 to 118 kmph)
Very Severe Cyclonic Storm 64 to 119 knots (119 to 221 kmph)
Super Cyclonic Storm 119 knots and above (221 kmph and above)

Refrences –

The Hindu

National Cyclone Risk Mitigation Project