scholarly journals Recently discovered small polar motion loops and their atmospheric excitation mechanism

2008 ◽  
Vol 113 (B4) ◽  
Author(s):  
Thomas J. Johnson
Keyword(s):  
Polar Motion ◽  
Excitation Mechanism ◽  
Atmospheric Excitation

scholarly journals Short-Period Oscillations of Earth Rotation

2000 ◽  
Vol 178 ◽  
pp. 533-544 ◽  
Author(s):  
B. Kołaczek ◽  
W. Kosek ◽  
H. Schuh
Keyword(s):  
Seasonal Variations ◽  
Earth Rotation ◽  
Polar Motion ◽  
Correlation Coefficients ◽  
Data Sets ◽  
Annual Variations ◽  
Geodetic Vlbi ◽  
Atmospheric Excitation ◽  
Short Period ◽  
Seasonal Oscillations

AbstractSub-seasonal variations and especially sub-seasonal oscillations with periods of about 120, 60, 50, 40 days in polar motion and of about 120, 60–90, and 50 days in LOD are presented. Variations of amplitudes of these sub-seasonal oscillations of polar motion are shown. Maxima of these amplitudes are of the order of 2–4 mas. These oscillations are elliptical ones. The correlation coefficients between geodetic and atmospheric excitation functions in this range of the spectrum are variable and have annual variations. Maxima of correlation coefficients are of the order of 0.6–0.8.Modern geodetic VLBI experiments provide very accurate results in polar motion and UT1–UTC with a temporal resolution of 3–7 minutes. Several irregular, quasi-periodic variations were found. In many UT1–UTC data sets, oscillations with periods around 8 hours and between 5 and 7 hours can be seen.

scholarly journals Polar motion of the triaxial nonrigid Earth and atmospheric excitation

2011 ◽  
Vol 14 (3) ◽  
pp. 223-229
Author(s):  
Wei Chen ◽  
Wenbin Shen
Keyword(s):  
Polar Motion ◽  
Atmospheric Excitation

Atmospheric excitation of polar motion during the GIG '91 Measurement Campaign

1992 ◽  
Vol 19 (9) ◽  
pp. 849-852 ◽  
Author(s):  
Richard S. Gross ◽  
Ulf J. Lindqwister
Keyword(s):  
Polar Motion ◽  
Measurement Campaign ◽  
Atmospheric Excitation

Atmospheric excitation of nonseasonal polar motion

1993 ◽  
Vol 98 (B11) ◽  
pp. 19973-19978 ◽  
Author(s):  
John Kuehne ◽  
Stuart Johnson ◽  
Clark R. Wilson
Keyword(s):  
Polar Motion ◽  
Atmospheric Excitation

scholarly journals Regional Signals in Atmospheric and Oceanic Excitation of Polar Motion

2000 ◽  
Vol 178 ◽  
pp. 463-472 ◽  
Author(s):  
Jolanta Nastula ◽  
Rui M. Ponte ◽  
David A. Salstein
Keyword(s):  
Atmospheric Pressure ◽  
Polar Motion ◽  
Ocean Model ◽  
Global Ocean ◽  
Relative Role ◽  
Bottom Pressure ◽  
Regional Patterns ◽  
Excitation Functions ◽  
Atmospheric Excitation ◽  
Environmental Prediction

AbstractAtmospheric and oceanic variability have been shown to play a role in the excitation of polar motion. Regional patterns of atmospheric and oceanic excitation are analysed and compared. The equatorial excitation functions, χ1 an χ2, for the ocean are computed using velocity and mass fields from a near-global ocean model, driven by observed surface winds stresses, surface heat and freshwater fluxes, for the period from January 1985 to June 1997. To understand the relative role of the ocean versus the atmosphere, we used atmospheric excitation functions computed from the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalyses. We consider regional mass terms [bottom pressure and atmospheric surface pressure with the inverted barometer (IB) correction] and regional motion terms as well (currents and winds). Results here confirm recent findings that oceans supplement the atmosphere as an important source for polar motion excitation. Regional signals in the oceanic bottom pressure terms have comparable amplitudes to those in the atmospheric pressure-IB terms. The regional wind term amplitudes, however, are several times larger than the values for both regional oceanic currents term and atmospheric pressure-IB term. Power in regional oceanic excitation is distributed between seasonal and subseasonal timescales while in the case of atmospheric excitation it is concentrated rather at seasonal timescales.

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