LASG;
Institute of Atmospheric Physics Academia Sinica;
Beijing 100080eatures of structure and propagation of the 30 to SO day atmospheric oscillations are investigated using the ECMWF analysis of 1980-1983. Evidence is provided to confirm the characteristics of the oscillation in the equatorial region. Those in the mid-high latitudes;
however;
are revealed to be very different from the tropics and pose a strong barotropic structure. Horizontal coherence shows teleconnection patterns which can be identified as EAP and PNA. The wind field of the specified time scale of the oscillation appears as long-lived vortices and vortex pairs. Mid-latitude perturbations propagate clearly westwards;
especially during the winter season. In the high latitudes;
they propagate westwards in the winter but eastwards in the summer. Meridional propagations are rather different from region to region.;
winter; latitude; season; ECMWF; perturbations; vortex; equatorial; oscillation; propagate; monsoon;