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Why is Indian Ocean warming consistently?

Rao, SA and Dhakate, AR and Saha, SK and Mahapatra, S and Chaudhari, HS and Pokhrel, S (2012) Why is Indian Ocean warming consistently? Climatic Change, 110 (3-4). pp. 709-719.

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Abstract

Observations have shown that the Indian Ocean is consistently warming and its warm pool is expanding, particularly in the recent decades. This paper attempts to investigate the reason behind these observations. Under global warming scenario, it is expected that the greenhouse gas induced changes in air-sea fluxes will enhance the warming. Surprisingly, it is found that the net surface heat fluxes over Indian Ocean warm pool (IOWP) region alone cannot explain the consistent warming. The warm pool area anomaly of IOWP is strongly correlated with the sea surface height anomaly, suggesting an important role played by the ocean advection processes in warming and expansion of IOWP. The structure of lead/lag correlations further suggests that Oceanic Rossby waves might be involved in the warming. Using heat budget analysis of several Ocean data assimilation products, it is shown that the net surface heat flux (advection) alone tends to cool (warm) the Ocean. Based on above observations, we propose an ocean-atmosphere coupled positive feedback mechanism for explaining the consistent warming and expansion of IOWP. Warming over IOWP induces an enhancement of convection in central equatorial Indian ocean, which causes anomalous easterlies along the equator. Anomalous easterlies in turn excite frequent Indian ocean Dipole events and cause anti-cyclonic wind stress curl in south-east and north-east equatorial Indian ocean. The anomalous wind stress curl triggers anomalous downwelling oceanic Rossby waves, thereby deepening the thermocline and resulting in advection of warm waters towards western Indian ocean. This acts as a positive feedback and results in more warming and westward expansion of IOWP.

Item Type: Article
Additional Information: Copyright of this article belongs to Springer.
Uncontrolled Keywords: Advection process; Air sea flux; Anomalous winds; Down-welling; Equatorial Indian Ocean; Heat budget analysis; Indian ocean; Indian Ocean dipole; Ocean data assimilation; Ocean-atmosphere; Rossby wave; Sea-surface height anomalies; Surface heat fluxes; Warm pools; Warm water; Wind stress curl, Advection; Data processing; Expansion; Feedback; Global warming; Greenhouse gases; Lakes; Ocean currents; Wind stress, Heat flux, advection; air-sea interaction; anticyclone; data assimilation; downwelling; environmental stress; global warming; greenhouse gas; heat budget; observational method; Rossby wave; sea surface height; thermocline, Indian Ocean; Indian Ocean (Equatorial)
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 21 Dec 2013 06:29
Last Modified: 21 Dec 2013 06:29
URI: http://moeseprints.incois.gov.in/id/eprint/531

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