IMF BY dependence of the extent of substorm westward electrojet |
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| Authors: | T Arun Ajay Dhar K Emperumal B M Pathan |
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| Institution: | (1) Indian Institute of Geomagnetism, Kalamboli (Highway), New Panvel, 410 218 Navi Mumbai, India |
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| Abstract: | In this paper the duskward extension of the westward auroral electrojet is investigated for substorm intervals on the basis
of magnetograms recorded at the Indian Antarctic station, Maitri. The database comprises three years from 1998–2000. Based
on an initial study of the magnetograms, an arbitrary local time of 2030 MLT is fixed to define the early manifestation of
the substorm westward electrojet. Using this criterion 12 substorms are identified and the possible causes examined. Many
of these events are observed to be associated with a moderate to intense ring current. The hourly average of the GSM BY-component of the interplanetary magnetic field (IMF) for the hour preceding the substorm onset at Maitri is negative for
most of the events. It is suggested that the azimuthal shift of the auroral electrojets in the southern hemisphere resulting
from a negative BY-component of the IMF influences the extent of the substorm westward electrojet. This finding implies that the IMF may have
a role in controlling the longitudinal extent of substorm occurrence. |
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| Keywords: | Interplanetary magnetic field westward auroral electrojet substorm ring current |
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