Indian Monsoon and India’s Extreme Rainfall ‘Corridor’

December 13, 2023

GS Paper III Environment and Ecology

Context: Existence of a stationary element in the dynamics of Indian monsoon since 1901-2019, where the synchronized extreme rainfall events occur and are restricted to a corridor, finds a new study.

Key Findings of Study on Indian Monsoon

Trends in Indian monsoon: For more than seven decades, total seasonal rainfall has trended downwards due to differential heating of land masses and sea due to global warming.
Large-scale extreme rainfall events: Intense wet spells particularly over Central India have become larger in scale due to the influence of the Arabian Sea and the Bay of Bengal combined.
The ‘highway’/corridor: It extends from parts of West Bengal and Odisha to parts of Gujarat and Rajasthan, making it a narrow highway or corridor of concentrated large-scale extreme rainfall events.
Capturing Complex Rainfall Relationships: Traditional statistical methods tend to miss the complex relations between multiple nodes of rainfall centers.
- Nodes are the Centre points of concentrated rainfall over a period of time considered for the study purpose.
Unpredictability of the Indian Monsoon: Stationary elements no longer exist in climate systems because of global warming.
- Yet the Indian monsoon continues to produce surprises in the way it is able to synchronize heavy rain events as well as stick to the ‘highway’ for such a long time.

About Indian Monsoon

Definition: Indian Monsoon is a seasonal change in the direction of the prevailing, or strongest, winds of a region.
India gets southwest monsoon winds in the summers (formation of an intense low-pressure system over the Tibetan Plateau) and northeast monsoons during the winters (due to the high-pressure cells that are formed over the Siberian and Tibetan plateaus.)
Features:
- Onset( may- june): factors affecting arrival of monsoon
  - Intense low-pressure formation over the Tibetan Plateau due to intense heating of landmass during summers
  - The permanent high-pressure cell in the South of the Indian Ocean near madagascar
  - Subtropical jet stream
  - African Easterly jet (Tropical easterly jet)
  - low-pressure systems (or monsoon depressions), presence of ITCZ (InterTropical Convergence Zone)

Inter Tropical Convergence Zone: It is a belt of low pressure zone which circles the Earth generally near the equator where the trade winds of the Northern and Southern Hemispheres come together.

Learn more about ‘Onset’ Of The Monsoon, here.

News source: The Hindu