Dynamics of the intraseasonal oscillations of the Indian south equatorial current

The intraseasonal oscillations have periods of 40-80 days with a wavelength of ~650 km. They originate from the southeastern Indian Ocean and propagate westward as Rossby waves with a phase speed of 25 cm s⁻¹ in boreal winter and spring.

The baroclinic instability is the main driver for these intraseasonal oscillations. The first baroclinic mode dominates during most of the year, but during boreal winter and spring the second mode contributes significantly and often equally. Consequently, the intraseasonal oscillations are relatively strong in boreal winter and spring.