A Preliminary Study of 3—5 Year Cycle over 500 hPa Height Field in the Northern Hemisphere

In the paper, the time series of 500 hPa height departure field from Jannary 1951 to December 1986 are calculated by using a band-pass filter at all grid points in the northern Hemisphere. The preliminary results are as follows: ① There exists a 3—5 year cycle for 500 hPa height field in the northern Hemisphere. The relative variance are over 30% in the northern Hemisphere and 50% to the south of 35oN latitude. The maximun relative variances in the Pacific, Atlantic and Eurasia low latitute area are more than 70%. ② The 3—5 year cycle is provided with more obvious construction of wavetrain than wallace’s teleconnection types. The atmospheric encrgy is transferred by dispersing from low latitude to high latitude along ray path of the wavetrains. ③ From the filtered 500 hPa height departure field during 1982/1983 El Nino event, it is found that in response of atmospheric circulation to the tropical Pacific SST anomaly forcing, there may be another path, in addition to the PNA teleconnection type.