Context:
- Recently, Australian Bureau of Meteorology has reported a shift in the Indian Ocean Dipole (IOD) index in recent days.
- The IOD index has increased from +0.34°C to +0.79°C, surpassing the positive IOD threshold of +0.4°C.
- Last Positive IOD event occurred in 2019.
About Indian Ocean Dipole (IOD):
- IOD signifies the fluctuation in sea-surface temperatures from warm to cool in the Indian Ocean area south of Sri Lanka.
- The IOD is defined by the difference in sea surface temperature between western Indian Ocean and eastern Indian Ocean south of Indonesia.
- The IOD affects the climate of Australia and other countries that surround the Indian Ocean Basin, and is a significant contributor to rainfall variability in this region.
About IOD index:
- IOD index is defined as the difference between the mean sea surface temperature in the western Indian Ocean and mean sea surface temperature in the eastern Indian Ocean.
- When the IOD index is positive, the phenomenon is referred to as the positive IOD and when it is negative, it is referred to as the negative IOD.
Positive IOD |
Negative IOD |
- Warmer sea surface temperatures in the western Indian Ocean relative to the east.
- Indonesia and Australia tend to be drier than normal, which increases the chances of bushfires, while eastern Africa tends to be wetter than normal, increasing the likelihood of floods.
- It helps rainfall along the African coastline and also over the Indian subcontinent.
- Positive IOD event is known to help the South-West monsoon.
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- Cooler sea surface temperatures in the western Indian Ocean relative to the east.
- Winds become more westerly, bringing increased cloudiness to Australia’s northwest.
- Indonesia and Australia tend to be wetter than normal, while eastern Africa tends to be drier than normal.
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News Source: Hindu BL
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