Asymmetry of the Geomagnetic Variations at the Conjugate Stations, Cape Wellen and Macquarie Island, in the Northern and Southern Hemispheres
Nagai, M.
Abstract
Asymmetry of the geomagnetic variations at the conjugate stations in the northern and southern hemispheres are analyzed, using the hourly values of horizontal intensity at Cape Wellen (CWE) and Macql1arie Island (MCQ) during 1961-1964 and 1966-1967.
Main results are as follows:
(1) Relatively large trends of +20nT/year at CWE and -25nT/year at MCQ in the secular variations are found at the conjugate stations.
(2) There are different patterns of seasonal variations on quiet and disturbed days. Semi-annual variations are seen on quiet days, which have almost symmetrical pattern in summer and winter. On the other hand，the seasonal variations on disturbed days have particl1larly large amplitudes at both stations in summer，showing asymmetrical pattern.
(3) Solar-daily variations on quiet (Sq) and disturbed (Sd) days are shown asymmetrical patterns, respectively.
(4) In the variation of the polar disturbance, sharp minimums are seen at the onset time of breakup, and it is shown that the amplitude of disturbance at MCQ is larger about by 40nT than that at CWE throughout the period of activity.
(5) The highly developed magnetic storms with large Dst-index indicate that the differences in the horizontal intensity between the northern and southern stations, (CWE-MCQ), increases with a increase of AU or AL-index, showing complicated variations.
