At the Earth’s poles, energetic particles that are injected into the atmosphere can chemically react and form nitric oxide (NO) molecules, which then descend through the atmosphere and can destroy ozone there. Previous studies have found that intense geomagnetic events lead to the largest descents of NO, but more recent research—following a large flux of NO in a period of quiet geomagnetic activity—suggests that such fluxes can have different origins.
Instead, Bailey et al. suggest, the largest movements of NO are triggered by stratospheric sudden warming (SSW) events—when interactions between different atmospheric waves slow or reverse the polar night jet stream, causing a sudden and significant warming in the stratosphere. The authors confirmed these findings by studying a 2013 SSW and the subsequent NO descent, using data from the Solar Occultation for Ice Experiment (SOFIE). The instrument, which is aboard an orbiting satellite, uses methane, water, and NO as tracers of atmospheric movement.
The authors tracked the resulting descent of NO and found that it was one of the largest of such events on record, confirming previous suggestions that it does not necessarily depend on geomagnetic activity. They note, however, that more research is needed to determine the meteorological effects on NO transport to fully understand the phenomenon. (Geophysical Research Letters, doi:10.1002/2014GL059860, 2014)
—JoAnna Wendel, Staff Writer
Citation: Wendel, J. (2014), What causes nitric oxide to infiltrate the ozone layer?, Eos Trans. AGU, 95(49), 472, doi:10.1002/2014EO490018.