In an attempt to find the role of subsurface Indian Ocean on the evolution of Indian Ocean Dipole, Rao et al (2001) carried out an empirical and numerical modelling study. They showed that significant subsurface changes in the Indian Ocean occur only during the IOD events and not during the El Nino years by contradicting several previous studies. They also found that the first two dominant EOF modes of the subsurface temperatures are closely connected with the Indian Ocean Dipole. Rao et al., (2001) further showed that the subsurface Indian Ocean helps in reversing the polarity of the surface dipole through propagation of Rossby waves in the off-equatorial regions.
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First complex EOF mode of |
Correlation of eastern IO (90°-110°E; 10°S-10°N) sea surface height anomalies with basin-wide SST anomalies at different lags |
Reference:Suryachandra Rao A., S.K.Behera, Y.Masumoto and T.Yamagat. Interannual variability in the subsurface Indian Ocean with a special emphasis on the Indian Ocean Dipole. 2001 Deep Sea Research-II, 49, 1549-1572. (Manuscript in pdf) (Figures in pdf)