Transport versus energetic particle precipitation: Northern polar stratospheric NO_x and ozone in January–March 2012

Abstract

In early 2012, a strong sudden stratospheric warming (SSW) took place, accompanied by several medium-scale solar proton events (SPEs). Here we use a chemistry transport model (CTM) in order to assess the relative contributions of (1) intensified downward transport of odd nitrogen (NO x ) and (2) in situ production of NO x by protons, on stratospheric NO x and ozone during January-March 2012. The CTM is constrained by an upper boundary condition for reactive nitrogen (NO y ) species, based on satellite observations from Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board Envisat, and includes a new parameterization of the SPE-caused effects on NO y and odd hydrogen (HO x ) species. We found that the amount of NO x increases due to both transport and in situ production effects, the intensified descent of NO x dominating the middle and upper stratospheric impact. The model results indicate NO x enhancements of 120-3300% (5-48 ppbv) between 38 and 50 km, caused by the transport of mesosphere/lower thermosphere NO x down to the stratosphere following the SSW. The SPEs increase NO x by up to 820-1200% (14-21 ppbv) at 33 to 50 km. The effect on the stratospheric ozone is larger following the downward transport of NO x than during and after the SPEs. The model predicts ozone losses of up to 17% and 9% at around 40 km due to transport and SPE effects, respectively.

Mesospheric ozone destruction by high‐energy electron precipitation associated with pulsating aurora

“…While solar proton events have been studied extensively for their in situ atmospheric effects [e.g., Jackman et al, 2001;Verronen et al, 2006;Funke et al, 2011], most studies on energetic electron precipitation (EEP) have concentrated on the so-called indirect effect in the wintertime polar regions [e.g., Seppälä et al, 2007;Randall et al, 2009;Päivärinta et al, 2016;Damiani et al, 2016]. The indirect effect requires that odd nitrogen (NO x = N + NO + NO 2 ), first produced by EEP in the lower thermosphere and mesosphere, descends to lower altitudes inside the polar vortex and catalytically destroys ozone in the stratosphere.…”

“…While substantial work has been devoted to understand the origin of the phenomenon and related wave-particle interactions in the magnetosphere [e.g., Nishimura et al, 2010;Thorne et al, 2010;Miyoshi et al, 2015b], we still do not quantitatively know the role of this energy input in altering the atmospheric state. The reason is the poor experimental quantification of precipitating electron fluxes [Rodger et al, 2010a], as input to atmospheric modeling.…”

HEPPA-II model–measurement intercomparison project: EPP indirect effects during the dynamically perturbed NH winter 2008–2009

“…However, the ability of the model to adequately simulate mesospheric tracer transport could not be tested because of the constrained NO x in the mesosphere. Salmi et al (2011) and Päivärinta et al (2016), in turn, used FinROSE with constrained NO x at the upper boundary (∼ 80 km) for both early 2009 and 2012. Their results show that FinROSE is able to qualitatively reproduce the downward descent of NO x from the MLT region into the stratosphere, but the actual NO x amounts can differ significantly from the observations.…”

Magnetic local time dependency of radiation belt electron precipitation: impact on polar ozone

“…positive and negative ions and is designed for particle precipitation studies in the mesosphere and upper stratosphere (Verronen et al, 2016). This allows for detailed simulations of the ion-neutral chemistry interaction leading to HO x production, in contrast 60 to simple parameterizations that are typically used.…”