IISc Study Finds Key Factors Affecting Indian Monsoon Rains

A recent study by the Indian Institute of Science (IISc) has challenged previous theories on monsoon rain patterns. 

• The study reveals that the strength of a cloud band plays a crucial role in both its movement and the intensity of rainfall during India’s monsoon season.

Understanding Indian Monsoon Rains

• The Indian monsoon is vital for the country, as it provides about 80% of the annual rainfall needed for drinking water and agriculture. 
  • The rains occur between June and September, driven by cloud bands moving northward from the equator.

What Are Cloud Bands?

• A cloud band is a nearly continuous formation of clouds that influences weather patterns. 
• In the context of the Indian monsoon, a cloud band moves from the equator towards India, bringing wet spells.

Role of BSISO in Monsoon Rainfall

• The Boreal Summer Intraseasonal Oscillation (BSISO) is a key weather phenomenon that controls wet and dry spells during the monsoon. 
• It moves cloud bands from the equator to the Indian subcontinent.

Key Findings of the Study

• Strength of Cloud Bands Matters: Earlier theories suggested that cloud bands always move northward, regardless of their initial strength.
  • The IISc study found that weak cloud bands fail to move northward, affecting rainfall patterns.
• Stronger Cloud Bands Bring More Rain: When the cloud band at the equator is strong, it increases atmospheric moisture.
  • This triggers stronger winds that help push the cloud band northward, leading to heavier rainfall.
• Impact of Ocean-Atmosphere Interaction: The interaction between the Indian Ocean and the atmosphere plays a major role in monsoon rainfall.
  • Warmer atmospheric conditions in the future will likely increase moisture levels, leading to stronger wet spells.

Future Implications: More Intense Rains

• The study predicts that rainfall during wet spells may increase by 42% to 63% due to rising atmospheric moisture levels. 
• This could impact water availability, agriculture, and flood risks in India.

Significance of New Study

• The findings will help improve climate models, leading to better monsoon and seasonal rainfall predictions. 
• This can assist in planning for agriculture, water management, and disaster preparedness.