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Missing driver in the Sun-Earth connection from energetic electron precipitation impacts mesospheric ozone.

Andersson ME, Verronen PT, Rodger CJ, Clilverd MA, Seppälä A - Nat Commun (2014)

Bottom Line: However, the long-term mesospheric ozone variability caused by EEP has not been quantified or confirmed to date.On solar cycle timescales, we find that EEP causes ozone variations of up to 34% at 70-80 km.With such a magnitude, it is reasonable to suspect that EEP could be an important part of solar influence on the atmosphere and climate system.

View Article: PubMed Central - PubMed

Affiliation: Earth Observation, Finnish Meteorological Institute, PO Box 503 (Erik Palménin aukio 1), Helsinki FI-00101, Finland.

ABSTRACT
Energetic electron precipitation (EEP) from the Earth's outer radiation belt continuously affects the chemical composition of the polar mesosphere. EEP can contribute to catalytic ozone loss in the mesosphere through ionization and enhanced production of odd hydrogen. However, the long-term mesospheric ozone variability caused by EEP has not been quantified or confirmed to date. Here we show, using observations from three different satellite instruments, that EEP events strongly affect ozone at 60-80 km, leading to extremely large (up to 90%) short-term ozone depletion. This impact is comparable to that of large, but much less frequent, solar proton events. On solar cycle timescales, we find that EEP causes ozone variations of up to 34% at 70-80 km. With such a magnitude, it is reasonable to suspect that EEP could be an important part of solar influence on the atmosphere and climate system.

No MeSH data available.


Related in: MedlinePlus

Magnitude of the long-term EEP effects on mesospheric ozone.(a–c) Ozone anomalies (%) of deseasonalized daily means, averaged over the winter time. (a) November to February in the Northern hemisphere from GOMOS showing years 2003 (blue line) and 2008–2009 (red line). (b) November to February in the Northern hemisphere from SABER showing years 2003 (blue line) and 2008–2009 (red line). (c) May to August in the Southern hemisphere from MLS showing years 2005 (blue line) and 2009 (red line). Black lines: winter time climatology from 2002 to 2012; grey area: 95% confidence range of the climatological mean. Subplots: winter time average ECRs between 2002 and 2012.
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f3: Magnitude of the long-term EEP effects on mesospheric ozone.(a–c) Ozone anomalies (%) of deseasonalized daily means, averaged over the winter time. (a) November to February in the Northern hemisphere from GOMOS showing years 2003 (blue line) and 2008–2009 (red line). (b) November to February in the Northern hemisphere from SABER showing years 2003 (blue line) and 2008–2009 (red line). (c) May to August in the Southern hemisphere from MLS showing years 2005 (blue line) and 2009 (red line). Black lines: winter time climatology from 2002 to 2012; grey area: 95% confidence range of the climatological mean. Subplots: winter time average ECRs between 2002 and 2012.

Mentions: Although the duration of the forcing for individual EEP events is only a few days, the high frequency of the events during active years (Fig. 1a) is enough to cause variability in mesospheric ozone on solar cycle timescales (Fig. 3a–c). Determining EEP-related ozone anomaly as a function of year or solar cycle is not straight forward because the temporal distribution of EEP events does not smoothly vary across the solar cycle. For example, the majority of the strong EEP events were observed during the declining phase of SC23, with a peak in year 2003 (Fig. 1). Instead, we can look at the EEP impact by contrasting periods of maximum and minimum EEP activity, which is then an indication of the maximum variability during the solar cycle. On the basis of the strength and frequency of the EEP (Fig. 3a,b, Subplots), for GOMOS and SABER we selected wintertime 2003 and 2008–2009 as maximum and minimum EEP periods, respectively. For MLS data, because they do not cover 2003, we selected year 2005 to represent the EEP maximum (Fig. 3c, Subplot). Before the analysis, we carefully removed SPE-influenced periods from all data sets. For example, in November 2003 (Fig. 2a) we excluded days 1–8 which, according to previously published satellite observations of ozone789, were affected by the Halloween 2003 SPE. The wintertime ozone values are much smaller during the EEP maximum than during the EEP minimum. The largest differences, ~21% for GOMOS (Fig. 3a) and 34% for SABER (Fig. 3b), are observed at the altitudes of 70–80 km that are known to be most strongly affected by EEP. For MLS, the difference between years 2005 and 2009 is smaller (~9%), which is consistent with weaker forcing in 2005 compared with 2003 (Fig. 3, Subplots). Note that the ozone anomalies during the EEP maximum and minimum years are outside the 95% confidence range of the climatological mean from 2002 to 2012 (Fig. 3).


Missing driver in the Sun-Earth connection from energetic electron precipitation impacts mesospheric ozone.

Andersson ME, Verronen PT, Rodger CJ, Clilverd MA, Seppälä A - Nat Commun (2014)

Magnitude of the long-term EEP effects on mesospheric ozone.(a–c) Ozone anomalies (%) of deseasonalized daily means, averaged over the winter time. (a) November to February in the Northern hemisphere from GOMOS showing years 2003 (blue line) and 2008–2009 (red line). (b) November to February in the Northern hemisphere from SABER showing years 2003 (blue line) and 2008–2009 (red line). (c) May to August in the Southern hemisphere from MLS showing years 2005 (blue line) and 2009 (red line). Black lines: winter time climatology from 2002 to 2012; grey area: 95% confidence range of the climatological mean. Subplots: winter time average ECRs between 2002 and 2012.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4214406&req=5

f3: Magnitude of the long-term EEP effects on mesospheric ozone.(a–c) Ozone anomalies (%) of deseasonalized daily means, averaged over the winter time. (a) November to February in the Northern hemisphere from GOMOS showing years 2003 (blue line) and 2008–2009 (red line). (b) November to February in the Northern hemisphere from SABER showing years 2003 (blue line) and 2008–2009 (red line). (c) May to August in the Southern hemisphere from MLS showing years 2005 (blue line) and 2009 (red line). Black lines: winter time climatology from 2002 to 2012; grey area: 95% confidence range of the climatological mean. Subplots: winter time average ECRs between 2002 and 2012.
Mentions: Although the duration of the forcing for individual EEP events is only a few days, the high frequency of the events during active years (Fig. 1a) is enough to cause variability in mesospheric ozone on solar cycle timescales (Fig. 3a–c). Determining EEP-related ozone anomaly as a function of year or solar cycle is not straight forward because the temporal distribution of EEP events does not smoothly vary across the solar cycle. For example, the majority of the strong EEP events were observed during the declining phase of SC23, with a peak in year 2003 (Fig. 1). Instead, we can look at the EEP impact by contrasting periods of maximum and minimum EEP activity, which is then an indication of the maximum variability during the solar cycle. On the basis of the strength and frequency of the EEP (Fig. 3a,b, Subplots), for GOMOS and SABER we selected wintertime 2003 and 2008–2009 as maximum and minimum EEP periods, respectively. For MLS data, because they do not cover 2003, we selected year 2005 to represent the EEP maximum (Fig. 3c, Subplot). Before the analysis, we carefully removed SPE-influenced periods from all data sets. For example, in November 2003 (Fig. 2a) we excluded days 1–8 which, according to previously published satellite observations of ozone789, were affected by the Halloween 2003 SPE. The wintertime ozone values are much smaller during the EEP maximum than during the EEP minimum. The largest differences, ~21% for GOMOS (Fig. 3a) and 34% for SABER (Fig. 3b), are observed at the altitudes of 70–80 km that are known to be most strongly affected by EEP. For MLS, the difference between years 2005 and 2009 is smaller (~9%), which is consistent with weaker forcing in 2005 compared with 2003 (Fig. 3, Subplots). Note that the ozone anomalies during the EEP maximum and minimum years are outside the 95% confidence range of the climatological mean from 2002 to 2012 (Fig. 3).

Bottom Line: However, the long-term mesospheric ozone variability caused by EEP has not been quantified or confirmed to date.On solar cycle timescales, we find that EEP causes ozone variations of up to 34% at 70-80 km.With such a magnitude, it is reasonable to suspect that EEP could be an important part of solar influence on the atmosphere and climate system.

View Article: PubMed Central - PubMed

Affiliation: Earth Observation, Finnish Meteorological Institute, PO Box 503 (Erik Palménin aukio 1), Helsinki FI-00101, Finland.

ABSTRACT
Energetic electron precipitation (EEP) from the Earth's outer radiation belt continuously affects the chemical composition of the polar mesosphere. EEP can contribute to catalytic ozone loss in the mesosphere through ionization and enhanced production of odd hydrogen. However, the long-term mesospheric ozone variability caused by EEP has not been quantified or confirmed to date. Here we show, using observations from three different satellite instruments, that EEP events strongly affect ozone at 60-80 km, leading to extremely large (up to 90%) short-term ozone depletion. This impact is comparable to that of large, but much less frequent, solar proton events. On solar cycle timescales, we find that EEP causes ozone variations of up to 34% at 70-80 km. With such a magnitude, it is reasonable to suspect that EEP could be an important part of solar influence on the atmosphere and climate system.

No MeSH data available.


Related in: MedlinePlus