Australia: The Land Where Time Began

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Indian Ocean Dipole - Impact on the Equatorial Indian Ocean Salinity Budget

In this paper the authors analysed the salinity variability, based on observations, and ocean dynamics relating to it, in the equatorial regions of the Indian Ocean. Significant interannual salinity variability associated with the Indian Ocean Dipole (IOD) in the boreal autumn is shown by the results. When anomalous easterly winds prevail, during the positive IOD phase (pIOD) there is a strengthening of the western advection along the equator in summer, and there is a weakening of the eastward advection that is associated with a weakening of the Yoshida-Wyrtki Jet in the autumn. It is indicated by salinity analysis that the main cause of salinity anomalies is advection, the zonal component being the dominant component. The equatorwards large northern Indian Ocean salinity gradient is more important than the current anomalies as a determent of the asymmetric distribution of low-salinity advection, as zonal current anomalies are symmetric about the equator. Low-salinity water is advected westward in the mature phase of the pIOD, which then shoals the surface mixed layer, therefore a favourable condition is provided for warm sea surface temperatures in the western equatorial Indian Ocean. Low salinity water is advected across the equator to the southwestern Indian Ocean in the decay phase of the pIOD. At times when the pIOD occurs at the same time as an El Niņo event the strengthened off-equatorial anticyclonic circulations, which are associated with El Niņo, advect water of low salinity towards the pole following the decay phase.

Sources & Further reading

  1. Yuhong, Zhang, Du Yan, Zheng Shaojun, Yang Yali, and Cheng Xuhua. "Impact of Indian Ocean Dipole on the Salinity Budget in the Equatorial Indian Ocean." Journal of Geophysical Research: Oceans 118, no. 10 (2013): 4911-23.
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                                                                                           Author: M.H.Monroe  Email:     Sources & Further reading