The Influence of Solar Differential and Rigid Rotation on the Interplanetary Magnetic Field.
CALIFORNIA UNIV BERKELEY SPACE SCIENCES LAB
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The large-scale photospheric magnetic field has been shown to have 1 a differential rotation pattern not too different from that observed by Newton and Nunn for sunspots, and 2 a rigid rotation pattern for the solar magnetic sector boundaries. Since the observed interplanetary magnetic field has been shown to be closely related to the photospheric magnetic field, it is of interest to search for these two rotation properties in the interplanetary field. An autocorrelation of the direction of the interplanetary field observed during the interval 1962-1968 shows 16 recurrent peaks at intervals of approximately 27 days, i.e. the lag of the autocorrelation extends from 0 to slightly more than 16 x 27 days. The rotation period associated with the first peak is about 27.3 days, and the periods associated with subsequent peaks show a monotonic decline to slightly less than 27.0 days, with the last few peaks showing a suggestion of a constant period. This result is interpreted in terms of photospheric field having differential and rigid rotation properties, and in terms of an assumed change through the sunspot cycle of the heliographic latitude of the source of the interplanetary magnetic field observed near the earth. Author
- Atmospheric Physics