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A note on new indices for the equatorial Indian Ocean oscillation

Francis, PA and Gadgil, Sulochana (2013) A note on new indices for the equatorial Indian Ocean oscillation. In: JOURNAL OF EARTH SYSTEM SCIENCE, 122 (4). pp. 1005-1011.

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Official URL: http://dx.doi.org/10.1007/s12040-013-0320-0


It is now well known that there is a strong association of the extremes of the Indian summer monsoon rainfall (ISMR) with the El Nio and southern oscillation (ENSO) and the Equatorial Indian Ocean Oscillation (EQUINOO), later being an east-west oscillation in convection anomaly over the equatorial Indian Ocean. So far, the index used for EQUINOO is EQWIN, which is based on the surface zonal wind over the central equatorial Indian Ocean. Since the most important attribute of EQUINOO is the oscillation in convection/precipitation, we believe that the indices based on convection or precipitation would be more appropriate. Continuous and reliable data on outgoing longwave radiation (OLR), and satellite derived precipitation are now available from 1979 onwards. Hence, in this paper, we introduce new indices for EQUINOO, based on the difference in the anomaly of OLR/precipitation between eastern and western parts of the equatorial Indian Ocean. We show that the strong association of extremes of the Indian summer monsoon with ENSO and EQUINOO is also seen when the new indices are used to represent EQUINOO.

Item Type: Journal Article
Additional Information: Copyright of this article is belongs to INDIAN ACAD SCIENCES
Keywords: Indian summer monsoon variability; equatorial Indian Ocean oscillation; Indian Ocean dipole; El Nino and southern oscillation
Department/Centre: Division of Mechanical Sciences > Centre for Earth Sciences
Date Deposited: 02 Oct 2013 14:56
Last Modified: 02 Oct 2013 14:56
URI: http://eprints.iisc.ac.in/id/eprint/47441

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