Comparative analyses of CUTLASS Super Dual Auroral Radar Network HF radar data and images of the dayside ultraviolet aurora from the Polar far ultraviolet imager and the Visible Imaging System Earth Camera have revealed that the GSM y component of the interplanetary magnetic field (By) affects the relative positions of ultraviolet auroral emissions and the HF radar signature of the cusp in the postnoon sector during episodes of flux transfer at the magnetopause. When By is positive, the region of strong auroral emissions is found to be at the same latitude as the radar footprint of the cusp. When By is negative, the radar cusp is found to be poleward of the strong auroral emissions. These results are consistent with models of the ionospheric convection and field-aligned current response to reconnection at the magnetopause under positive and negative By conditions. We extend the models to predict the auroral and convection responses in the morning sector. ¿ 2001 American Geophysical Union