Influence of interplanetary magnetic field on global auroral patterns

We produce average patterns of global auroral brightness using images from the Polar Ultraviolet Imager (UVI). UVI measures auroral brightness at two wavelength bands within the N2 Lyman-Birge-Hopfield emission spectra, allowing a determination of average energy and total precipitating energy flux. The auroral patterns are organized by both season (to show the effects of solar UV flux on auroral patterns) and interplanetary magnetic field (IMF) orientation. One global pattern for each of eight IMF clock angles in the GSM YZ plane is presented. It is shown that the dependence of global auroral patterns on IMF changes with the season. The afternoon bright spot is more distinct from the nightside aurora for B_y < 0 than for By > 0 under large northward IMF or small IMF B_z conditions during the summer. The average position of the duskside aurora varies with the sign of IMF B _y during the summer. However, its location remains almost the same during the winter. Northern Hemisphere auroral power is greater for B _y < 0 than for B_y > 0. The B_y effect on auroral power is more pronounced when the southward IMF is larger.