Variations of Short Periodical Oscillations of Polar Motion with Periods Ranging from 10-140 Days
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Date
1992-04
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Ohio State University. Division of Geodetic Science
Abstract
At present, highly accurate Earth Rotation Parameters (ERP) determined by the use of Lageos Laser Ranging (SLR) and Very Long Baseline Interferometry (VLBI) enable not only the detection of short periodical oscillations of Earth Rotation, but also their investigation. Variations of short periodical oscillations with periods of 100-120, 80-90, 60, 50, and 30 days have been investigated based on SLR and VLBI Earth rotation parameters from the period 1980-1991 and 1983-1991 respectively. These oscillations are seen in the fast Fourier transform (FFT) spectra as double or multiple peaks showing their variabilities. The 100-120 days oscillations are the strongest ones. They are elliptical oscillations with variable amplitudes and orientations. Their amplitudes achieve about 4 milliarcseconds (mas) maxima. Other short periodical oscillations are weaker and also have amplitude variations with a period of about 2 years.
Description
For U.S. Naval Observatory, Washington, D.C.: Contract No. N10092-89-M-0429