High frequency tropical waves and MJO initiation

The wavelet analysis of TRMM precipitation in the equatorial area indicates that the initiation of MJO is often associated with bursts of small scale, high frequency, eastward propagating waves. The waves are accompanied by high wind velocities and large air-sea fluxes. The analysis of the shallow water model indicates that the short, intense waves may be forced by highly variable SST field. MJO episodes observed in DYNAMO and SST variability observed by ship and ocean sea glider measurements right before the MJO active phase appear to support this hypothesis The conclusions from DYNAMO observations are extended to other seasons and the longer period covered by the TRMM observations, to establish the prevalence of the short wave episodes in the MJO initial stages, the role of the waves in the moistening of the atmosphere before the active MJO phase and the role of the air sea interaction in triggering of these perturbations.