Influence of IMF by on the location of western electrojets during the magnetic storm on Nov. 9-10, 2004

The spatial-temporal distribution of westward electrojets in the northern hemisphere has been investigated using geomagnetic ground observation data for November 9-10, 2004 geomagnetic storm. It is shown that the location of the maximum westward electrojet depends on the IMF orientation. It is in the evening or morning sector when Bγ<0 or Bγ>0. With the increase of positive IMF Bγ, the region of intensity maximum shifts to morning hours. Thus, the azimuthal IMF component not only controls the pattern of magnetospheric convection, but also affects the longitudinal location of the westward electrojet pattern during the magnetic storm.