Simulation of the 14-month chandler wobble in a global climate model

The agent that generates and maintains the 14-month Chandler wobble of the solid earth about its rotation axis has remained unresolved for a century with first the atmosphere, later earthquakes, and more recently the earth's fluid core proposed as candidates. Here we report that surface air pressure calculated in a coupled ocean-atmosphere general circulation model (GCM) displays a 14.7 month signal, whose amplitude is similar to that found by Maksimov (1960) in station data; we identify it as the atmospheric Chandler wobble. This result indicates that changes in atmospheric mass distribution excite and maintain the wobble of the solid earth, and that neither earthquakes nor the fluid core are significant contributors. Another result is that in the GCM the amplitude of the wobble at high latitudes is a substantial fraction of the annual cycle, and thus is an important factor in climate formation as Maksimov (1960) suggested.