In this study, the characteristics and propagating mechanisms of the oscillation are also suggested from the coupled model result. The lagged correlation patterns are used to investigate relationships between the simulated atmospheric and oceanic variables associated with IO. The correlation patterns reveal that there are systematic relationships between convection, low-level wind, evaporation, downward shortwave radiation flux, low-level moisture convergence, upper-level zonal current and SST associated with the oscillation. Evaporation is increased (decreased) to the west (east) of the convective region, which is consistent with the observations. The result indicates that evaporation-wind feedback is not the dominant mechanism for promoting the eastward propagation of the IO. The relationship between convection and SST shows systematic changes in SST with warming to the east and cooling to the west of the convection. The increase of the SST in the east of the convection is related to downwelling, reduced evaporation and increased downward shortwave radiation flux, and the decrease of the SST in the west is due to upwelling, increased evaporation and decreased downward shortwave flux. The positive SST anomaly seems to provide favorable condition for convection to develop in the east of the convection region.
The results suggest that the role of interactive ocean is vital in the CGCM experiment for the simulation of IO and that the variation of SST as well as the low-level moisture convergence seems to be important to the eastward migration of the convection associated with IO.
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