Confirmation of Prediction of Geomagnetic Secular Change.
Evidence in support of the findings regarding a strong correlation between the change in the length of day and the change in westward velocity of the eccentric dipole of the geomagnetic field. In 1965, Ball and others made an empirical prediction "that the eccentric dipole (westward) velocity will decrease sharply during the next 5 years." A new model of the geomagnetic field for recent epochs was derived from data recorded by the OGO-2 and OGO-4 spacecraft for intervals from October 1965 through December 1967. Using this model, referred to as POGO (10/68), the motion westward is shown to be 0.114 deg/yr. This new value, shown graphically, confirms the predicted decrease. It also shows a level about equivalent to the level of a period 40 years earlier. 4 pp. Refs. (KB)