What are Walker circulations and how does it influence the Indian monsoons?

Walker circulation or east-west circulation or southern oscillation is a system developed especially in the South Pacific Ocean, resulting in East-West pressure differences creating currents.

• When the pressure is suddenly increased in the West Pacific Ocean, water from the west Pacific ocean moves along the wind to East Pacific. This is called the low phase of southern oscillation.
• When the pressure in the east Pacific is increased, wind and water start moving towards the west Pacific. This is called the high phase of southern oscillations.

• The first condition is called as El-Nino. It leads to rains in the East Pacific coast of Chile, Argentina, etc, and droughts in India, Indonesia, Australia, etc.
• The second condition is called as La-Nina. It is an augmented normal condition. It causes more than average rainfall in India, due to the intensification of low pressure. It also causes upwelling on the west coast of South America. It is associated with good Fish harvest and fertilizer production.
• El Nino events occur every 2-7 years. It has a dramatic impact on agriculture in India, due to the failure of monsoons and droughts.

Systems for prediction and adaptive major should be put in place to cope with the challenges associated with it.

Topics: GS-I: Salient Features of World Physical Geography • GS-I: Important Geophysical Phenomena