Features of Quasi–3.5 Year Oscillation of Zonal Wind in Troposphere

Using the monthly zonal wind data at 700 and 200 hPa during 1968—1985 analyzed by NMC, the features of quasi–3.5 year oscillation are discussed. It is found that the oscillation is mainly in the sourthern and northern hemispheres of 180 o—150oW and in the belt of 25o—35oN. It moves eastward over the equator and the midlatitude, and moves westward over the subtropics. For the meridional propagation, it is northward over the Pacific and there is no obvious propagation direction over the region of 50 o—90oE. The results of CEOF analysis show that the variance of oscillation is mainly concentrated at the first and second main component. In this paper, the evolution of oscillation and its relation to the 3.5 year oscillation of SSTA in the equatorial eastern Pacific are also discussed