Effects of solar wind density on auroral electrojets

During the magnetic cloud event of January 10-11, 1997, several density enhancements in the solar wind were observed while other solar wind parameters were relatively constant. By using this fortuitous opportunity, the effects of the solar wind density on the intensity of the auroral electrojets are examined. It is found that a positive relationship exists between the solar wind density and the intensity of the auroral electrojets. The relationship is found to be much weaker for northward interplanetary magnetic field (IMF) than for southward IMF. It is also shown that when the IMF is directed southward, the density effect is dominant in the westward electrojet, while it is most effective in the eastward electrojet when the IMF is directed northward.