The results show that the propagations of the atmospheric ISO in the East Asian monsoon region in summer include zonal propagation and longitudinal propagation.

By using complex empirical orthogonal function (CEOF), the longitudinal propagations and geographical features of the 10-20 day low-frequency oscillations have been discussed with the data of the daily 200 hPa ECMWF zonal wind data from July 1 to September 12, 1983.

When the basic zonal flow is barotropic, it is demonstrated that the cooling of the Tibetan Plateau in winter not only facilitates the meridional propagation of Rossby waves but is an important driving mechanism of the intraseasonal oscillations in middle and high latitudes.