Transport of thermospheric NOX to the stratosphere and mesosphere

Odd Nitrogen (NOX) is produced in the Earth's thermosphere when N2 is dissociated by solar radiation and energetic particle precipitation. Thermospheric production and downward transport in winter high latitudes gives rise to a polar reservoir containing very large quantities of NOX. This reservoir, which is maintained throughout the winter, can affect the photochemistry of the upper stratosphere and mesosphere. In particular, it can account for variations in the ozone concentration in the stratosphere associated with the 11-year solar cycle, and for the smooth and sporadic D-region winter anomalies. The results of numerical modeling studies bearing on these phenomena are compared with observations to ascertain the impact of the thermospheric NOX source on lower levels of the middle atmosphere.