Abstract
A method for analysis of the ultra-long waves in the atmosphere, which are represented by Fourier harmonics of the geopotential field etc., is presented. Firstly, the ultra-long waves are separated into the quasi-steady and the fluctuating parts by applying several band-pass and one low-pass time filters to the time series of Fourier harmonics. Secondly, the fluctuating parts, which pass through the band-pass filters, are devided into the transient part and the quasi-stationary part with temporal change of the amplitude, with the procedure of shifting the cosine and sine-time series by a quarter of the period. This method is applied to the geopotential field, and some preliminary results are given as an example.
