Analysis of Rapid Variations of Polar Motion Determined by GPS

Abstract

Accurate Earth Rotation Parameter (ERP) series, determined from GPS solutions, allow the study of rapid variations in polar motion, including the detection of oscillations with periods shorter than 12 hours. In this paper, the GPS (CODE) polar motion series in the period 1997.5 through 2001.0 with a resolution of two hours is studied using Fourier Transform Spectral Analysis. The resulting spectra display clear oscillations with periods of 12, 8 and 5–6 hours and have somewhat variable amplitudes throughout the 3.5 years under consideration.To check any association between such high frequency polar motion oscillations and atmospheric forcing a temporally dense set of equatorial Atmospheric Angular Momentum (AAM) functions with a resolution of three hours is analysed for the year 1995. In this series oscillations at a period around 8 and 12 hours were detected in the computed spectra as well.KeywordsPolar MotionGPSAtmospheric Angular Momentum