Discrete Aurora at Mars: Dependence on Upstream Solar Wind Conditions

At Mars, discrete aurora are defined by their small spatial extent and general tendency to form near strong crustal magnetic fields. They are produced when precipitating electrons enter the upper atmosphere and collide with neutral molecules, causing them to emit ultraviolet radiation. The auroral emissions are routinely detected by MAVEN’s Imaging Ultraviolet Spectrograph (IUVS) during nightside periapsis limb scans. In this presentation, we present a statistical study of the IUVS dataset that shows how the discrete aurora detection frequency depends on upstream solar wind conditions at Mars. We find that the probability of detecting an aurora increases during times of high solar wind dynamic pressure and increased interplanetary magnetic field (IMF) strength. We also find that the IMF clock and cone angles control the detection frequency and locations of the aurora. These results provide useful constraints for future theoretical and modelling studies that attempt to explain the physics of discrete aurora at Mars.