Variation in the Earth’s Angular Velocity Resulting from Fluctuations in Atmospheric and Oceanic Circulation

Fluctuations in the circulation of the atmosphere are associated with very small anomalies in the angular velocity of the earth. The seasonal component of these anomalies has been computed from weather maps, and is found to agree, with respect to magnitude and phase, with anomalies first reported by STOKYO in 1936 on the basis of astronomic observations. The effects of fluctuations in the oceanic circulation, and of shifting of air and water masses, have been estimated to account for not more than 15 per cent of the observed effect.

The detection of shorter period fluctuations is presently limited by the accuracy of astronomic time determination. The developments of an atomic clock and of the photographic zenith tube open the possibility of determining anomalies persisting for only two weeks, and of providing a new tool for obtaining an index of integrated atmospheric circulation.