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More Cyclones in Arabian Sea

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October 24, 2023

Why in news?

According to a new study, human induced climate change is causing more frequent and intense cyclones in the Eastern Arabian Sea.

What is a cyclone?

  • Cyclone - Any large system of winds that circulates about a centre of low atmospheric pressure in a counter-clockwise direction north of the Equator and in a clockwise direction to the south.
  • Occurrence - Cyclonic winds move across nearly all regions of the Earth except the equatorial belt.
  • Cause - By atmospheric disturbances around a low-pressure area distinguished by swift and often destructive air circulation.
  • Eye of the cyclone - Low-pressure center of the cyclone
    • The lower the pressure in the eye, the more intense is the cyclone.
  • Eye-wall - Surrounds the eye with the strongest winds and heaviest rain and is the most destructive part of the cyclone.

What about the cyclones in Arabian Sea?

  • The Bay of Bengal and Arabian Sea which make up the North Indian Ocean, accounts for 6% of all global tropical cyclones annually.
  • In 2021, a research paper in Nature journal said that there is a significant increasing trend in the intensity, frequency, and duration of cyclones observed over Arabian Sea during 1982 to 2019.
  • According to a 2022 paper in Elsevier’s Earth Science Reviews, the sea surface temperatures over the Arabian Sea increased by 1.2°C to 1.4°C in recent decades.
  • The paper highlighted that there is a 52% increase in the frequency of cyclones during 2001–2019 in the Arabian Sea, while there is a decrease of 8% in the Bay of Bengal.
  • There has been an 80% increase in the total duration of cyclones in the Arabian Sea during the last two decades.
  • Important cyclones in Arabian Sea
    • Cyclone Tej - 2023
    • Cyclone Biparjoy - 2023
    • Cyclone Tauktae – 2021
    • Cyclone Nisarga –  2020
    • Cyclone Kyarr- 2019
    • Cyclone Maha
    • Cyclone Maha
    • Cyclone Vayu

What reasons are attributed to increasing cyclones in Arabian Sea?

  • Global warming - It is causing surface sea temperatures to rise and causing a change in the Arabian Sea’s character.
  • This is leading to more severe cyclones forming and sustaining over it.
  • Vertical shear - It refers to how strongly the winds can change from the surface to the top of the atmosphere.
  • Weak vertical shear promotes the formation of cyclones.
  • Positive Indian Ocean dipole (IOD) phase – It refers to warmer sea surface temperatures in the western Indian Ocean relative to the east.
  • Warming of Arabian Sea can increase the frequency and intensity of tropical cyclones in the North Indian Ocean.

What are the impacts?

  • West India- As the eastern Arabian Sea changes, the coastlines of western India are increasingly at risk.
  • Intensity- Increase in intensity of cyclones increases their potential to cause high wind, storm surges, severe rainfall, etc.
  • Population- The cyclones could pose more and more of a threat to all densely populated coastal regions along the western coast, from Thiruvananthapuram to the coast of Gujarat.
  • Impact on fishers- It will affect the lives and livelihood of the indigenous coastal communities and artisanal fishers.
  • Impact on southwest monsoon – Its impact on southwest monsoon is concerning which as the country relies upon heavily for its drinking water and agricultural needs.

What lies ahead?

  • This report calls for changes to development strategies to account for the dangers posed by more intense and frequent cyclones.
  • There is also a need to develop new policy and technology initiatives in the areas of storm warning, impact-based local weather services and reliable localised weather services.

Related links- Monsoon Mayhem

Quick facts

Indian Metrological Department

  • It is the national meteorological service of the country and the principal government agency in all matters relating to meteorology and allied subjects.
  • Established- 1875
  • Headquarters- New Delhi
  • Aegis- Ministry of Earth Science
  • Mandate-
    • To take meteorological observations and to provide current and forecast meteorological information for optimum operation of weather-sensitive activities like agriculture, irrigation, shipping, aviation, offshore oil explorations, etc.
    • To warn against severe weather phenomena like tropical cyclones, norwesters, duststorms, heavy rains and snow, cold and heat waves, etc., which cause destruction of life and property.
    • To provide meteorological statistics required for agriculture, water resource management, industries, oil exploration and other nation-building activities.
    • To conduct and promote research in meteorology and allied disciplines.

References

  1. Indian Express- Frequent intense cyclones in west coast
  2. IMD- Indian Metrological Department
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