SOLAR SOURCE OF THE INTERPLANETARY SECTOR STRUCTURE.
CALIFORNIA UNIV BERKELEY SPACE SCIENCES LAB
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The interplanetary sector structure observed by the IMP-1 satellite during three solar rotations in 1963-64 is compared with the photospheric magnetic field structure observed with the solar magnetograph at Mt. Wilson Observatory. The interplanetary sector structure was most prominent on the sun in latitudes between 10 deg. N and 20 deg. N, although the average heliographic latitude of the satellite was 3 12 deg. S. A superposed-epoch analysis of the calcium plage structure obtained from the Fraunhofer Institute daily maps of the sun is used to discuss the relation between the structure of the plages and the interplanetary sector structure. A possible explanation for the observations is discussed in terms of a north-south asymmetry in the flow of the solar wind. It is suggested that these observations favor the equinoctial hypothesis as compared with the axial hypothesis for the explanation of the semiannual maxima in geomagnetic activity. Author