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A note on new indices for the equatorial Indian Ocean oscillation

Francis, PA and Gadgil, S (2013) A note on new indices for the equatorial Indian Ocean oscillation. Journal of Earth System Science, 122 (4). pp. 1005-1011.

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It is now well known that there is a strong association of the extremes of the Indian summer monsoon rainfall (ISMR) with the El Niño 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: Article
Additional Information: Copyright of this article belongs to Indian Academy of Sciences.
Uncontrolled Keywords: Indian summer monsoon variability; equatorial Indian Ocean oscillation; Indian Ocean dipole; El Ni˜no and southern oscillation
Subjects: Oceanography > oceanography
Depositing User: INCOIS Library
Date Deposited: 14 Dec 2013 05:33
Last Modified: 14 Dec 2013 05:33

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