Comparison of high frequency variations of the atmosphere and the polar motion

The inferred excitation function X-m derived from EOP(IERS 97C04) polar motion series and the series X-p and X-ib(p) of the atmospheric angular momentum (AAM) provided by NCEP/NCAR for 1988-1999 are used to assess the contribution of AAM to the polar motion. Power spectra and complex wavelet analysis show that there are high peaks and similar structures in X-m and X-p, and their cross correlation coefficient is 0.75 (retrograde) and 0.60 (prograde). The peaks in X-ib(p) are lower. The phase of X-p is about one day ahead of X-m. The indications are that atmosphere variation is the main source of excitation of polar motion in the high-frequency range, and particularly so for the retrograde motion, while there may be other sources