Mesopheric odd nitrogen enhancements during relativistic electron precipitation events

Abstract The behavior of mesospheric odd nitrogen species during and following relativistic and diffuse auroral precipitation events is simulated Below 75 km nitric oxide is enhanced in proportion to the ion pair production function associated with the electron precipitation and the length of the event. Nitrogen dioxide and nitric acid are also enhanced. At 65 Ian the percentage of odd nitrogen for N is 0.1%, HNO 3 is 1.6%, NO 2 is 15%, and NO is 83.3%. Between 75 and 85 km, NO is depleted during particle events due to the faster destruction of NO by N relative to the production of NO by N reacting with O 2 Recovery of NO depends on transport from the lower thermosphere, where NO is produced in abundant amounts during particle events.