scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...

STP12 Abstracts
Berlin, 12 - 16 July 2010
SCOSTEP Symposium 2010
Impact of energetic particle precipitation on the middle atmosphere
Randall Cora 1 , Harvey Lynn 1 , Jackman Charles 2 , Marsh Daniel 3 , Fang Xiaohua 1 , Mills Michael 3 ,
Lopez-Puertas Manuel 4 , Bailey Scott 5
1 University of Colorado, 2 NASA GSFC, 3 NCAR, 4 IAA, 5 Virginia Tech
Research into the effects of energetic particle precipitation (EPP) on the atmosphere has
expanded significantly in recent years. This is due to a combination of factors, including the
availability of more observations, improvements in models, and intriguing occurrences of EPP
effects, beginning with the 2003 “Halloween” storms. This talk will summarize our current
understanding of the middle atmosphere response to EPP, and will highlight some of the
recent advances in this field. In particular, emphasis will be placed on vertical coupling in the
polar regions, and the so-called “indirect effect” of EPP. In three of the last seven Arctic
winters, extraordinary meteorology in the SMLT (Stratosphere-Mesosphere-Lower-
Thermosphere) led to unusually strong descent of air from the mesosphere into the
stratosphere. In each of these three years (2004, 2006, 2009), the descent led to enhancements
in polar NOx mixing ratios that were larger than ever before recorded. These enhancements
have been attributed to EPP even though, in 2006 and 2009, geomagnetic activity levels were
lower than average. This talk will describe the observational evidence for this coupling, and
will put the results into the context of current modeling efforts.