Study by Juhi Yadav and colleagues titled "Contrasting response of regional spring Arctic Sea ice variations on Indian summer monsoon rainfall."
Published in the journal Remote Sensing of Environment, Vol 311, September 1, 2024.
Incessant Rainfall in India
Heavy rainfall in southeast India has caused destruction.
17 dead in Andhra Pradesh.
Thousands left homeless due to floods in Telangana.
Indian Meteorological Department warns of more rain in parts of Gujarat, Himachal Pradesh, and Delhi.
Erratic Indian Monsoon Patterns
Unpredictable and erratic rainfall has become common during the Indian monsoon season.
Once considered a bringer of relief, monsoons are now often associated with floods and drought.
Role of Climate Change
Climate change is a significant contributor to these erratic monsoon patterns.
Multiple factors, including surface temperature, pressure gradients, and sea ice, play roles in influencing the Indian monsoon.
Study Findings on Arctic Sea Ice and Monsoon
National Centre for Polar and Ocean Research (NCPOR) in India and Korea Polar Research Institute conducted the study.
Study shows a link between Arctic sea ice levels and the Indian monsoon.
Mechanics of the Indian Summer Monsoon
The Indian summer monsoon rainfall (ISMR) occurs from July to September, with peak rains in July and August.
The monsoon is driven by:
Low-pressure areas created by heating of the Indian landmass.
Coriolis force deflecting trade winds, bringing moisture from the Arabian Sea to India.
Two monsoon branches:
Arabian Sea arm (west coast).
Bay of Bengal arm (east and northeast India).
Influence of Oceans on Monsoon
Surface temperatures of the Indian, Atlantic, and Pacific Oceans significantly affect the ISMR.
Circum-global teleconnection (CGT), a large atmospheric wave, also influences monsoons.
Impact of Arctic Sea Ice
Arctic sea ice levels influence the Indian monsoon through complex atmospheric circulations:
Less sea ice in the central Arctic leads to:
Less rain in western and peninsular India.
More rain in central and northern India.
Less sea ice in the Barents-Kara Sea region causes:
Delayed and unpredictable monsoon onset.
Central Arctic sea ice increase triggers:
Cyclonic circulation in the North Atlantic, enhancing Rossby waves.
Rossby waves, also known as planetary waves, naturally occur in rotating fluids.
Within the Earth's ocean and atmosphere, these waves form as a result of the rotation of the planet.
Changes in Asian jet stream and subtropical easterly jet.
Resulting in high pressure over northwest India and more rain in western India.
Low sea ice in the Barents-Kara Sea triggers:
High pressure over southwest China.
Affects the Arctic Oscillation and weakens the CGT.
Causes anticyclonic circulation over northwest Europe, affecting monsoons in subtropical Asia.
Regional Monsoon Variations
High surface temperature of the Arabian Sea and moisture from nearby water bodies enhance rainfall in northeast India.
Central and northwest India may receive less rainfall.
Climate Change and Monsoon Variability
Climate change accelerates Arctic sea ice reduction, increasing ISMR variability.
Leads to more frequent droughts and flooding in different parts of India.
Urgency for Further Research
The study emphasizes the need for more research into climate dynamics.
Aims to improve forecasting of the increasingly unpredictable Indian monsoon.
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