05/08/2019 - Geography

KEY POINTS

·        The Indian Ocean Dipole (IOD) is a coupled ocean­atmosphere phenomenon in the Indian Ocean.

·        It is normally characterized by anomalous cooling of Sea Surface Temperature (SST) in the south eastern equatorial Indian Ocean and anomalous warming of SST in the western equatorial Indian Ocean.

Influence on monsoon of India

The IOD has three  phases such as Neutral, Positive and Negative IOD

Neutral Phase of IOD

·        During this phase Water flows from the Pacific between Indonesia’s islands, keeping seas warm to the northwest of Australia. Air rises above this area and falls across the western half of the Indian Ocean basin, blowing westerly winds along the equator. This has very less impact on Indian monsoon.

Positive Phase of IOD

·        During this phase the Westerly winds weaken along the equator, allowing warm water to move to Africa.

·        This creates a temperature difference across the tropical Indian Ocean with cooler than normal water in the east and warmer than normal water in the west. This event has been found to be beneficial for the monsoon, both southwest and northeast monsoon.

Negative Phase of IOD

·        During this phase westerly winds intensify along the equator,  allowing the concentration of warmer waters near Australia. This creates a temperature difference across the tropical Indian Ocean, with warmer than normal water in the east and cooler than normal water in the west. This event obstructs the progression of monsoon over India.

·        This is in turn attributable to the persisting negative phase of the Indian Ocean Dipole (IOD), which causes the Indian Ocean just south to Bay of Bengal to warm up abnormally.

·        This has direct implications for the North-East monsoon, since the warmth builds up lower pressure over the Indian Ocean where most of the moisture gets directed.

Kindly review, thank you

Pls review

Kindly review. Thank you. 

Kindly review. Thanks.