Thursday, 18 January 2007: 9:15 AM
The role of synoptic eddy and low-frequency flow (SELF) interaction in the MJO-midlatitude teleconnection
214B (Henry B. Gonzalez Convention Center)
The role of synoptic eddy and low-frequency flow (SELF) interaction in the MJO-midlatitude teleconnection is investigated by using observational data and numerical models. A statistic closure for describing synoptic eddy-low frequency flow (SELF) interaction is used, which is derived on the basis of observed synoptic eddy forcing and low-frequency anomaly. After validating the statistical closure with observational data, we use a barotropic model and a two and half layer model with such closure to investigate the role of SELF feedback in the midlatitude response to the tropical forcing associated with MJO heating. Both observational analysis and modeling studies show that the synoptic eddy forcing on the middlatitude response to the MJO heating mainly locates at the Pacific and Atlantic Storm track region, which has a positive feedback in the momentum field. It is also shown that the disturbance (e.g., synoptic scale vorticity forcing) in the midlatitude can excite/intensify MJO through Rossby wave propagation. The signal propagates from midlatitude to equator at a timescle around several days, which does not require westerly basic flow. Thus the MJO-midlatitude teleconnection mainly can be explained in terms of Rossby wave propagation and eddy-zonal flow interaction.