Energetic particle precipitation: A major driver of the ozone budget in the Antarctic upper stratosphere

Abstract

Geomagnetic activity is thought to affect ozone and, possibly, climate in polar regions via energetic particle precipitation (EPP) but observational evidence of its importance in the seasonal stratospheric ozone variation on long time scales is still lacking. Here we fill this gap by showing that at high southern latitudes, late winter ozone series, covering the 1979–2014 period, exhibit an average stratospheric depletion of about 10–15% on a monthly basis caused by EPP. Daily observations indicate that every austral winter EPP‐induced low ozone concentrations appear at about 45 km in late June and descend later to 30 km, before disappearing by September. Such stratospheric variations are coupled with mesospheric ozone changes also driven by EPP. No significant correlation between these ozone variations and solar ultraviolet irradiance has been found. This suggests the need of including the EPP forcing in both ozone model simulations and trend analysis.

NO<sub><i>y</i></sub> production, ozone loss and changes in net radiative heating due to energetic particle precipitation in 2002–2010

“…A clear negative downwelling signal of 5-30 % is observed in Antarctic winter 2003 from the lower mesosphere (≈ 0.3 hPa) in mid-winter to the lower stratosphere (below 10 hPa) in spring, preceded by a weaker (5-10 %) positive signal. The structure and strengths of this signal are similar to the downwelling anomalies derived from global satellite observations for the Southern Hemisphere (Fytterer et al, 2015a;Damiani et al, 2016) when comparing composites of years with high minus low geomagnetic activity, and are interpreted as particle impacts there. In the Northern Hemisphere, a similar negative downwelling signal starts in the lower mesosphere in early winter [2003][2004], but is interrupted by a strong (> 40 %) positive anomaly in late 2003 and early 2004 that is probably related to the onset of the sudden stratospheric warming.…”

“…Previous studies based on observations have compared observations of ozone in situations with and without elevated amounts of NO y on the same day and in the same latitude range (Natarajan et al, 2004), the evolution of ozone in years with high energetic particle fluxes compared to years with low particle fluxes (Randall et al, 2005), and the composite difference of years with high minus years with low particle fluxes (Fytterer et al, 2015a;Damiani et al, 2016). All methods have yielded lower values of ozone in the upper stratosphere presumably related to the energetic particle precipitation; the composite method also shows negative ozone anomalies proceeding downwards from the stratopause to the mid-stratosphere during polar winter.…”

“…Lower values of ozone in the upper stratosphere are observed during winters characterized by large particle forcing or enhanced values of NO y (Natarajan et al, 2004;Randall et al, 2005), and downwelling negative ozone anomalies were observed for the first time by Fytterer et al (2015a) and Damiani et al (2016). However, quantification of the particle-induced ozone loss by observations is difficult, because (a) MIPAS observations of EPP NO x show that EPP-induced ozone loss must occur in every year, so only relative differences can be obtained from observations; (b) stratospheric ozone is quite variable anyway; and (c) a much longer time series than used by (Fytterer et al, 2015a) would be necessary to attribute the observed anomalies clearly to the particle precipitation.…”

Solar forcing for CMIP6 (v3.2)

“…This has been postulated already by Solomon et al (1982) and observed many times (Callis et al, 1996;Stratospheric ozone loss due to electron-induced NO x production in the upper mesosphere-lower thermosphere and subsequent downward transport has been postulated by model experiments many times (Solomon et al, 1982;Schmidt et al, 2006;Marsh et al, 2007;Baumgaertner et al, 2009;Reddmann et al, 2010;Semeniuk et al, 2011;Rozanov et al, 2012). However, observational evidence for EPP-induced variations of stratospheric ozone linked to geomagnetic activity, characterized by a negative anomaly moving down with time during polar winter, have been given only very recently (Fytterer et al, 2015a;Damiani et al, 2016).…”

Climate impact of idealized winter polar mesospheric and stratospheric ozone losses as caused by energetic particle precipitation

“…Only recently have long-term satellite observations with good temporal and spatial coverage become available. In austral polar winter EPP causes an ozone loss of about 10-15 % descending from 1 hPa in early winter to 10 hPa in late winter (Fytterer et al, 2015;Damiani et al, 2016). Extensive information on the current knowledge of energetic particle precipitation can be found in Sinnhuber et al (2012) and Mironova et al (2015).…”