Memoirs of the Kakioka Magnetic Observatory Vol.15 No.02， p.107, December, 1973

Variations of Focus Latitude and Intensity of Overhead Current System of Sq with the Solar Activity

Shiraki, M.

Abstract

 A simple method to estimate focus latitude of Sq is presented. Using this method latitude changes due to the solar activity are studied in the West Pacific and the North American regions. The changes are large in winter for both regions, and the center of focus is in higher latitude during solar quiet years than that during solar active years. The changes in equinox and summer are smaller than that in winter, and in summer the change shows rather opposite sense. Consequently, the seasonal changes of focus latitude are different between the active and quiet years of the sun.
  A measure of intensity is obtained simultaneously and the relation between the measure and the sunspot number is also examined. The coefficient m of the relation shows seasonal and regional differences. The largest value of m in winter is consistent with the large change of focus latitude in winter.

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