Accession Number : AD0684116

Title :   CONFIRMATION OF PREDICTION OF GEOMAGNETIC SECULAR CHANGE,

Corporate Author : RAND CORP SANTA MONICA CALIF

Personal Author(s) : Kahle,Anne B. ; Ball,R. H. ; Cain,J. C.

Report Date : FEB 1969

Pagination or Media Count : 6

Abstract : In two recent papers it was shown that a strong (0.93) correlation exists between the change in the length of day and the change in westward velocity of the eccentric dipole or 'magnetic center' of the geomagnetic field. The correlation is presumed to be due to the necessity to conserve angular momentum of the earth. If one assumes that the motion of the eccentric dipole is related to a motion somewhere in the core in which the magnetic field is 'frozen' into the fluid, then a change in westward motion and angular momentum in the core must be compensated by a change in angular momentum of the mantle. This appears as a change in the length of day, as determined astronomically. Calculation of the eccentric dipole motion depends primarily on the secular change rather than the main field. Therefore, although these new data have been referred back to the arbitrary epoch 1965, they best represent the state of the eccentric dipole motion at the epoch during which the data were acquired -- the period October 1965-December 1967. Using this model the eccentric dipole motion is westward at 0.114 degrees/year. (Author)

Descriptors :   (*GEOMAGNETISM, MOTION), MATHEMATICAL PREDICTION, SCIENTIFIC SATELLITES, MOMENTUM, TIME

Subject Categories : Geomagnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE