Daily variation of the equatorial geomagnetic field in the vicinity of the IMF sector boundaries

Abstract

The response of the equatorial geomagnetic field to the passage of over 170 spacecraft-observed and well-established sector boundaries during the period 1962-1972 has been studied. It is shown from superposed epoch analysis of the daily range of magnetic field from 10 days before to 10 days after sector boundary crossings, that the significant aspect of the association is not mainly the increase in the daily range following the boundary crossing, but also the minimum of the daily range before crossing. A distinct difference in the responses of the range of daily variation with respect to the type of boundary passage, namely, a transition from positive to negative polarity and negative to positive polarity, has been noticed.