Polar vortex evolution during SSWs influenced by energetic electron precipitation

Many studies have shown that energetic electron precipitation (EEP) depletes ozone in the mesosphere and upper stratosphere, inducing radiative and dynamical changes in the wintertime stratosphere, which enhance the polar vortex. Past studies have indicated that EEP may affect the probability of sudden stratospheric warmings (SSWs), events where the stratospheric polar vortex momentarily collapses. Here we study the stratospheric response to EEP during SSWs and find that that the polar vortex is enhanced by EEP only during winters with SSW. By concentrating on the times around the SSW onset dates we show that the EEP also influences the evolution of the polar vortex during the SSWs. This is evident primarily during the first two weeks after the SSW onset, so that during periods of high EEP, the polar vortex recovers faster. These responses are related to anomalous planetary wave convergence before and divergence after the SSW in the polar stratosphere.