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Difficulty: MediumClimate, Weather Systems, and Monsoon of India

Which of the following atmospheric and oceanic features actively contribute to strengthening the South-West Monsoon system over the Indian subcontinent?

  1. The upper-tropospheric anticyclone formed over the intensely heated Tibetan Plateau during summerAnswer
  2. The semi-permanent high-pressure cell known as the Mascarene High near Madagascar in the Southern Indian OceanAnswer
  3. C
    The prevalence of strong El Niño conditions in the central and eastern equatorial Pacific Ocean
  4. D
    The persistent southward displacement of the Inter-Tropical Convergence Zone (ITCZ) away from the Ganga plains during July

Answer

The mechanisms that actively strengthen the South-West Monsoon are the upper-tropospheric anticyclone over the heated Tibetan Plateau and the Mascarene High in the Southern Indian Ocean.
The South-West Monsoon system relies on two critical drivers: the upper-tropospheric anticyclone over the Tibetan Plateau, which generates the Tropical Easterly Jet and maintains monsoon circulation, and the Mascarene High in the Southern Indian Ocean, which drives moisture-rich cross-equatorial winds into the Indian subcontinent.

Step-by-Step Solution

1
Analyze thermal and dynamic drivers over Asia during summer
Intense thermal heating over the high-altitude Tibetan Plateau creates a thermal ridge and high-pressure anticyclone in the upper troposphere (~200 hPa). Air diverging from this anticyclone forms the Tropical Easterly Jet (TEJ), which reinforces the low-level monsoon trough over India.
Tibetan heating is a major dynamic thermal engine for monsoon onset and maintenance.
2
Analyze oceanic pressure hubs in the Southern Hemisphere
The Mascarene High, positioned at ~30°S near Madagascar, serves as the pressure gradient source pushing southeast trade winds north across the equator. Upon crossing the equator, these winds deflect right due to the Coriolis force, becoming the moisture-laden South-West Monsoon winds.
A strong Mascarene High directly enhances cross-equatorial flow and monsoon rainfall strength.
3
Evaluate Pacific and ITCZ anomalous influences
El Niño creates descending air over the western Pacific and Indian Ocean, weakening monsoon winds. Similarly, a southward shift of the ITCZ during peak summer causes a break in the monsoon over Northern India.
Both factors suppress, rather than strengthen, South-West Monsoon activity.

Key Concept

Driving Mechanisms and Atmospheric Circulation of the Indian South-West Monsoon
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Topics

Climate, Weather Systems, and Monsoon of India

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