Different response of dayside auroras to increases in solar wind dynamic pressure

Variations in the solar wind dynamic pressure can create changes in the auroral brightness, especially in the dayside region. In this study, mainly using Polar Ultraviolet Imager auroral images and NASA OMNI magnetic field and plasma data, we investigate the relationship between interplanetary parameters and dayside aurora intensification. We first identify the dayside aurora cases caused by the solar wind dynamic pressure increases from 1997 through 1999 and divide these cases into two types: one with intensification and the other without significant intensification following the increase in the solar wind dynamic pressure. Then, case by case, we examine the separate roles of the solar wind density and velocity on auroral brightness. Our result demonstrates that the dayside aurora intensification requires the contributions of both the density and solar wind velocity increases. The solar wind density increase alone (without velocity increase) could not create the dayside aurora intensification.