Atmospheric response to NO_y source due to energetic electron precipitation

Abstract

We have introduced additional NO y sources caused by energetic electron precipitation (EEP) during 1987 into a Chemistry‐Climate model. Comparison of two model runs with and without EEP reveals increase of reactive nitrogen by about 2 ppbv in the middle stratosphere over the tropical and middle latitudes. In the upper stratosphere over the polar winter regions the simulated NO y enhancement reaches 10 ppbv. Decreases of the ozone mixing ratio in the stratosphere by up to 5% over midlatitudes and up to 30% over southern high‐latitudes are calculated. A ∼0.5 K cooling in the middle stratosphere over the tropics and up to 2 K over southern high‐latitudes is calculated with detectable changes in the surface air temperatures. These results confirm that the magnitude of the atmospheric response to EEP events can potentially exceed the effects from solar UV fluxes. These mechanisms work in phase outside polar latitudes, but can compensate each other within polar latitudes.