A multiscale model for tropical intraseasonal oscillations.

The tropical intraseasonal 40- to 50-day oscillation (TIO) is the dominant component of variability in the tropical atmosphere with remarkable planetary-scale circulation generated as envelopes of complex multiscale processes. A new multiscale model is developed here that clearly demonstrates the fashion in which planetary-scale circulations sharing many features in common with the observational record for the TIO are generated on intraseasonal time scales through the upscale transfer of kinetic and thermal energy generated by wave trains of organized synoptic-scale circulations having features in common with observed superclusters. The appeal of the multiscale models developed below is their firm mathematical underpinnings, simplicity, and analytic tractability while remaining self-consistent with key features of the observational record. The results below demonstrate, in a transparent fashion, the central role of organized vertically tilted synoptic-scale circulations in generating a planetary circulation resembling the TIO.