RAS question
The Indian Ocean Dipole (IOD) affects:
Correct answer: (D) Indian monsoon and regional weather patterns.
The Indian Ocean Dipole affects the Indian monsoon and wider regional weather patterns through sea-surface-temperature oscillations in the Indian Ocean.
Explanation
The Indian Ocean Dipole is a climate pattern built around an east-west contrast in Indian Ocean sea-surface temperatures. NOAA Climate.gov explains that, in a positive IOD phase, cooler-than-normal waters near Java and Sumatra occur with warmer-than-normal waters in the western tropical Indian Ocean, and this contrast alters wind, temperature and rainfall patterns in the region. A positive IOD typically brings more rainfall to India and East Africa, while a negative IOD can contribute to drought conditions in India. The effect is not confined to one country or continent; IOD influences the Indian monsoon as well as regional weather patterns around the Indian Ocean.
Why the other options are wrong
- (A) African climate is part of the IOD impact zone, but the pattern also affects India and other regional weather patterns, so it is not only an African climate phenomenon.
- (B) The IOD involves Indian Ocean sea-surface-temperature contrasts and regional rainfall effects, not a direct role in Arctic ice melting.
- (C) Australia can be affected by the IOD, but the pattern also affects India, East Africa and wider regional weather patterns, so it is not limited to Australia's climate.
Concept
Climate oscillations are linked with monsoon variability, a recurring Environment and Geography theme in RAS. IOD is important because ocean-atmosphere patterns can have broader regional consequences rather than narrow local effects.