Anticyclones, hanging even now over India, link warming to heat

• During its pre-monsoon demise El Nino’s impact on the Indian Easterly Jet tends to produce a stronger and more persistent anticyclone which is leading to long lasting and intense heat waves.

Highlights:

• In March, the anticyclonic circulations over the North Indian Ocean created unusual rainfall over Odisha.
• Global warming creates unique features locally that modulate heat waves on top of cool background temperatures.
• Heat waves over India have been of special concern this season
  • Some persistent circulation patterns have been creating heat waves and this pattern serves as a focal point for improving predictions.

Anticyclones:

• In anticyclonic conditions winds move in a clockwise direction, with air sinking down in the middle of it. The air is compressed and warmed as it hits the ground and can create a high pressure heat dome.
• During the pre-monsoon season,
  • The upper-level Indian Easterly Jet (IEJ) begins to take shape in the upper atmosphere, across the Arabian Sea, peninsular India, and the Bay of Bengal.
  • A strong westerly jet exists to the north.
• During the monsoon season the westerly jet is pushed north and the IEJ dominates the Indian subcontinent.
• Anticyclonic conditions can be generated by these two over the Indian Ocean and the Indian subcontinent.
• A strong anticyclone can bring dry and hot weather over many parts of India while a weak anticyclone produces milder weather.

Way forward:

• India’s prediction system and early warning systems have improved.
  • However, challenges remain to build resilience for the future by better predicting the trajectory of the weather at every location over India.
• Governments, their departments, and the people at large need to be trained and engaged with to make this a sustained success.

Prelims Takeaway

• ANTICYCLONE
• CYCLONE