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Equatorial Indian Ocean provided warmth to the mother Earth in past 137,000 years
The most densely populated area of the Earth is the tropical region. The tropical sea surface temperature (SST) influence the amount and duration of rainfall in this area. Today, the tropical western Pacific contains the warmest water, and is an important reservoir of heat on the planet. The sea surface temperature (SST) in the tropical Indian Ocean also remains consistently high throughout the year, thus making it a part of the world's oceanic warm pool ( oceanic warm pool is a warm water mass, with seawater warmer than 28 ?C, throughout the year). However, at present, the tropical Indian Ocean is not as warm as western equatorial Pacific (WEP). The warm pool keeps fluctuating annually and geographically, leading to changing east-west gradients in tropical SST that contribute to El-Nino Southern Oscillation (ENSO) and other related processes. The foraminifera, the tiny organisms with jelly-like body and a calcareous or sandy test (shell) usually divided into chambers and perforated with small apertures are very sensitive to the climatic fluctuations. The tests of foraminifera are found in the sediments and their presence in the sediments help in understanding the climatic conditions during the past. One of the species of foraminifera - Globigerinoides ruber was used by the scientists of NIO to understand the SST of the past 137,000 years and therefore draw conclusions on the changing extent of the warm pool, the east-west gradients and its influence on ENSO. Based on the studies, the scientists have arrived at a conclusion that throughout the larger part of the last ~137 ka BP, equatorial Indian Ocean (EIO) was the warmest part of the tropics except for a brief period during penultimate glacial?interglacial transition. At this time, the eastern equatorial Pacific (EEP) Ocean was warmer than both the WEP and EIO. The SST difference between EIO and EEP as well as between WEP and EEP shows strong positive correlation over the entire period of ~137 ka BP, suggesting that during the large part of the past glacial period, more intense and frequent El-Nino-like conditions persisted and influenced the tropical Indian and Pacific oceans.
For more information please read:
Saraswat, R.; Nigam, R.; Weldeab, S.; Mackensen, A.
A tropical warm pool in the Indian Ocean and its influence on ENSO over the past 137, 000 yrs BP.
Curr. Sci.: 92(8); 2007; 1153-1156.
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