Atmospheric excitation of polar motion during the GIG '91 Measurement Campaign
Abstract
Daily determinations of the Earth's pole position from Global Positioning System (GPS) observations acquired during the first GPS IERS and Geodynamics (GIG) experiment held during January 22, 1991 to February 13, 1991 are interpreted in terms of atmospheric wind and pressure fluctuations as parameterized by the atmospheric angular momentum (AAM) χfunctions. All available AAM χfunctions spanning the GIG '91 period have been collected and compared to the observations in the time and polar motion domains. The greatest level of agreement is obtained using the total (wind plus pressure) χfunctions from the Japanese Meteorological Agency (JMA) where the pressure term is computed by assuming the inverted barometer approximation. In this case, the correlation coefficient between the observed and JMAinduced polar motion series is 0.91 for the xcomponent and 0.72 for the ycomponent, the rms of the difference between the observed and JMAinduced series is 0.71 mas for the xcomponent and 0.69 mas for the ycomponent, and the percentage of the variance of the observed series explained by the JMAinduced series is 83% for the xcomponent and 48% for the ycomponent. Thus, it is demonstrated that atmospheric wind and pressure fluctuations are largely responsible for exciting the rapid polar motions observed during GIG '91.
 Publication:

Geophysical Research Letters
 Pub Date:
 May 1992
 DOI:
 10.1029/92GL00935
 Bibcode:
 1992GeoRL..19..849G
 Keywords:

 Atmospheric Effects;
 Earth Axis;
 Earth Rotation;
 Global Positioning System;
 Angular Momentum;
 Correlation Coefficients;
 Pressure Effects;
 Wind Effects;
 Geophysics;
 Geodesy and Gravity: Rotational variations;
 Geodesy and Gravity: Instruments and techniques;
 Meteorology and Atmospheric Dynamics: General circulation;
 Meteorology and Atmospheric Dynamics: Waves and tides