Early Onset of Southwest Indian Monsoon

Context

According to the IMD, there are possibilities of early onset of the southwest monsoon. The normal onset date of the monsoon over Kerala is June 1 and it typically takes approximately 10 days for the system to reach Kerala from the Nicobar islands.

Mechanism of the Indian Monsoon: The Driving Forces

• Differential Heating of Land and Sea: In summer, India’s landmass heats faster than the sea, growing low pressure over land and drawing in moisture-encumbered winds from the sea.
• Inter-Tropical Convergence Zone (ITCZ): The ITCZ, in which trade winds meet near the equator, shifts north during summer season, intensifying low strain over the Indo-Gangetic plain and drawing in monsoon winds.
• Tibetan Plateau: Its high elevation heats up, developing an upper-air low-pressure region that strengthens vertical move and draws monsoon winds.
• Tropical Easterly Jet: Develops all through the summer season, strengthening monsoon trough and rainfall.

ENSO

• • El Niño: Warms Pacific waters, typically weakening Indian monsoon.
  • La Niña: Cools Pacific, often strengthening monsoon.

• Indian Ocean Dipole (IOD):

• • Positive IOD: Strengthens monsoon with warm western Indian Ocean.
  • Negative IOD: Weakens monsoon.

Onset and Advancement

• Arabian Sea Branch: Hits Kerala round June 1, movements up the west coast, bringing heavy rain to Western Ghats and inland states.
• Bay of Bengal Branch: Reaches Northeast India in early June, then movements westward alongside the Indo-Gangetic simple. India is generally completely included by mid-July.
• Retreat of the Monsoon: Retreat starts in October from northwest India. Clear skies and residual moisture cause hot, humid conditions called “October heat.”
  • Reversal of wind direction brings rain to the southeastern coast, considerably Tamil Nadu and Andhra Pradesh.

Impact of the Monsoon

• Agriculture: Essential for Kharif crops like rice and maize. A good monsoon improves yields; a bad one leads to drought.
• Economy: Monsoon-linked agriculture affects GDP, rural income, and food prices.
• Water Resources and Hydropower: Rains recharge rivers and reservoirs, crucial for drinking water, irrigation, and energy.
• Environment and Culture: Supports biodiversity and cultural traditions like fairs celebrating rain.
• Disasters: Heavy rains can trigger floods, landslides, and other disasters, specifically in inclined regions.

Recent Government Initiatives to Improve Monsoon Forecasting

• Monsoon Mission: Launched in 2012 by the Ministry of Earth Sciences it was a significant initiative aimed at improving the accuracy of monsoon forecasting.
• National Supercomputing Mission: Aimed at enhancing computational infrastructure needed for running high-end dynamical climate models.
• ICAR & IMD Collab: The IMD, in collaboration with the Indian Council of Agricultural Research (ICAR), gives Agromet Advisory Services.

Source: The Indian Express

UPSC Mains Practice Question

Q. What do you understand by the phenomenon of temperature inversion in meteorology? How does it affect weather and the inhabitants of the place? (2013)

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