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Impact of Indian Ocean Dipole and El Nio/Southern Oscillation wind-forcing on the Wyrtki jets

Gnanaseelan, C and Deshpande, A and McPhaden, MJ (2012) Impact of Indian Ocean Dipole and El Nio/Southern Oscillation wind-forcing on the Wyrtki jets. Journal of Geophysical Research C: Oceans, 117 (8).

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Interannual variability of the Wyrtki jets is studied in the context of Indian Ocean Dipole (IOD) and El Nio and Southern Oscillation (ENSO) wind-forcing using a three dimensional numerical ocean model and observations. The boreal fall (October-November) Wyrtki jet is more significantly affected than the boreal spring (April-May) Wyrtki jet since both the IOD and ENSO tend to peak toward the end of the calendar year. Various statistical methods are used in an attempt to separate the impacts of the IOD and ENSO on these jets, with emphasis on the fall jet. The first two modes of an Empirical Orthogonal Function (EOF) decomposition account for about 90 and 85 of variability in zonal currents and wind stress respectively along the equator in the Indian Ocean, but EOF analysis does not cleanly separate out IOD and ENSO forcing and response. Partial correlation analysis reveals that IOD wind-forcing and zonal equatorial current response are stronger on average than for ENSO and extend further west across the basin. Composite analysis of IOD only, ENSO only, and combined IOD and ENSO years provides a complementary definition of the relative contributions of these two phenomena on Wyrtki jet variability and in general is consistent with the results of the partial correlation analysis.

Item Type: Article
Additional Information: Copyright of this article belongs to American Geophysical Union.
Uncontrolled Keywords: Boreal Spring; Composite analysis; Current response; Empirical orthogonal function decompositions; Indian ocean; Indian Ocean dipole; Indian ocean dipoles; Interannual variability; Ocean model; Partial correlation; Relative contribution; Southern oscillation; Zonal currents, Atmospheric pressure; Ocean currents; Separation; Three dimensional, Correlation methods, annual variation; El Nino-Southern Oscillation; jet stream; numerical model; seasonality; three-dimensional modeling; wind forcing; wind stress
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 04 Jan 2014 17:47
Last Modified: 04 Jan 2014 17:47

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