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Plots of Past EO

Plots of Historic Earth Orientation Variations

Polar motion -- x component Polar motion -- y component Excess Length of Day (LOD) -- corrected to remove tides due to the solid Earth and oceans

Comparison Plots of Earth Orientation Variations and Atmospheric Excitation

Variations in the distribution and flow of the Earth's fluid constituents are thought to be responsible for the observed variations in the Earth's polar motion and rate of rotation (UT1). This reflects the physical principle of conservation of angular momentum for the whole-Earth system, including both the solid and fluid parts.

The plots below compare the geodetically observed EOP variations with the expected effects due to the atmosphere. While the atmosphere is only one of the geophysical fluids responsible for EOP variations, it is the most important and most accurately observed. The atmosphere data used here are produced by the National Centers for Environmental Prediction (NCEP) as a byproduct of their meteorological assimilation models. Two time series of geodetic observations are shown for comparison -- the Bulletin A combination and the IGS Final series based on GPS data only.

Polar motion -- x component Polar motion -- y component Excess Length of Day (LOD) -- corrected to remove tides due to the solid Earth and oceans

 

 

 

 

 

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