The impact of sudden stratospheric warming events on energetic particle precipitation effects
Abstract
The main source of stratospheric NOx (NO+NO2) is N2O from the troposphere. Another source of stratospheric NOx in the polar region is energetic particle precipitation (EPP). EPP produces NO in the mesosphere and lower thermosphere (MLT). During the polar night the EPP-produced NOx (EPP-NOx) can be transported to the stratosphere without being photochemically destroyed. The process whereby EPP-NOx is transported to the stratosphere from the MLT is referred to as the EPP indirect effect (EPP IE). In the Southern Hemisphere the EPP IE is highly correlated with the level of EPP; however, in the Northern Hemisphere (NH) interannual variability in dynamics is an important factor controlling the EPP IE. In the most recent decade we have ample observational evidence of the importance of dynamics. January 2004, 2006 and 2009 had major sudden stratospheric warming (SSW) events followed by a reformation of the stratopause at an altitude characteristic of the mesosphere. This is known as an elevated stratopause (ES) event. Multitple satellite instruments have shown strong descent of NOx into the stratosphere following the ES event in all three years even though the level of EPP was relatively low during the 2005-2006 and 2008-2009 NH winters. In the work presented here we investigate the effects of SSW and ES events on the magnitude of the EPP IE. We find a very strong relationship between the seasonal timing of major SSW and ES events and the strength of the EPP IE.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMSA22A..06H
- Keywords:
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- 0341 ATMOSPHERIC COMPOSITION AND STRUCTURE Middle atmosphere: constituent transport and chemistry;
- 0342 ATMOSPHERIC COMPOSITION AND STRUCTURE Middle atmosphere: energy deposition