AGU: Geophysical Research Letters

 

Editors' Highlight

Quantifying the variation in motion of the Earth's rotation pole on weekly scales

The motion of the Earth's rotation pole shows two large trends, one with a period of about 433 days corresponding to Chandler wobble (free Eulerian wobble), and another corresponding to annual oscillations forced by the seasonal displacement of air and water masses. Every 6.4 years, annual and Chandler wobble combine to almost cancel each other out, severely reducing polar motion. Noting that between November 2005 and February 2006 Chandler and annual wobble interfered destructively, Lambert et al. (2006) sought to characterize the small amount of wobble left, a value representing wobble on weekly scales. Using high-precision Earth orientation data for these days, the authors were able to directly observe the very small structures of this weekly wobble for the first time in the history of polar motion observation. They also calculated the polar motion predicted during this time interval from atmospheric and oceanic circulation models, and found that the centimeter-level polar motion displacements during the 2005–2006 winter season are almost fully explained by major pressure events on the continents and on the ocean.

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