N2O production by high energy auroral electron precipitation

The Fourier transform spectrometer on SCISAT-1 observed enhanced concentrations of N2O above 50 km in February of 2004 and 2006 in the wintertime polar region. These anomalously high concentrations are associated with the transport of high levels of NOx in the polar night region from the upper mesosphere and lower thermosphere in both cases following sudden warming events in the middle of January. The NOx is produced by auroral electron precipitation. Simulations using a middle atmosphere chemistry climate model show significant amounts of N2O are produced in the upper mesosphere from the reaction of NO2 and ground state atomic nitrogen. Thus, N2O acts as a signature of energetic electron precipitation. The model results exhibit polar-night-confined descent of NOx in the wake of sudden warmings and other dynamical regimes when the polar vortex intensifies at high latitudes in the mesosphere.