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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.


Signature of EEP in observed mesospheric ozone.(a) Monthly mean ECRs (black bars), maximum proton flux >10 MeV (red numbers) in proton flux units (1 pfu=1 p cm−2 sr−1 s−1) and sunspot number (SSN, grey area) between 2002 and 2012. (b,c) Maximum O3 loss (%) at altitudes between 70 and 78 km in the Northern hemisphere (b) and Southern hemisphere (c) during 60 EEP events, with daily ECR >150 (counts s−1). Numbers: the average O3 loss (%) for each set of available satellite measurements (MLS, SABER and GOMOS).
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f1: Signature of EEP in observed mesospheric ozone.(a) Monthly mean ECRs (black bars), maximum proton flux >10 MeV (red numbers) in proton flux units (1 pfu=1 p cm−2 sr−1 s−1) and sunspot number (SSN, grey area) between 2002 and 2012. (b,c) Maximum O3 loss (%) at altitudes between 70 and 78 km in the Northern hemisphere (b) and Southern hemisphere (c) during 60 EEP events, with daily ECR >150 (counts s−1). Numbers: the average O3 loss (%) for each set of available satellite measurements (MLS, SABER and GOMOS).

Mentions: Solar cycle 23 (SC23) was one of the longest cycles since 1847 and exhibited large variation in solar (UV radiation) and geomagnetic activity (solar storms, energetic particle precipitation). In 2003, during the declining phase of SC23, the majority of the days were geomagnetically disturbed. In contrast, the deep solar minimum that occurred in 2009 showed the lowest activity since the beginning of the Twentieth century. The current solar cycle (SC24) is so far the weakest cycle in the last 100 years. For this period, EEP events were strongest and most frequent during the transition between SC23 maximum and the following minimum (Fig. 1a). Almost 75% of all major EEP events (major=daily mean electron precipitation count rate exceeding 150 counts s−1) in the 2002–2012 period occurred between 2003 and 2006. The occurrence of solar proton events (SPEs) peaked during high solar activity (red numbers in Fig. 1a).


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)

Signature of EEP in observed mesospheric ozone.(a) Monthly mean ECRs (black bars), maximum proton flux >10 MeV (red numbers) in proton flux units (1 pfu=1 p cm−2 sr−1 s−1) and sunspot number (SSN, grey area) between 2002 and 2012. (b,c) Maximum O3 loss (%) at altitudes between 70 and 78 km in the Northern hemisphere (b) and Southern hemisphere (c) during 60 EEP events, with daily ECR >150 (counts s−1). Numbers: the average O3 loss (%) for each set of available satellite measurements (MLS, SABER and GOMOS).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: Signature of EEP in observed mesospheric ozone.(a) Monthly mean ECRs (black bars), maximum proton flux >10 MeV (red numbers) in proton flux units (1 pfu=1 p cm−2 sr−1 s−1) and sunspot number (SSN, grey area) between 2002 and 2012. (b,c) Maximum O3 loss (%) at altitudes between 70 and 78 km in the Northern hemisphere (b) and Southern hemisphere (c) during 60 EEP events, with daily ECR >150 (counts s−1). Numbers: the average O3 loss (%) for each set of available satellite measurements (MLS, SABER and GOMOS).
Mentions: Solar cycle 23 (SC23) was one of the longest cycles since 1847 and exhibited large variation in solar (UV radiation) and geomagnetic activity (solar storms, energetic particle precipitation). In 2003, during the declining phase of SC23, the majority of the days were geomagnetically disturbed. In contrast, the deep solar minimum that occurred in 2009 showed the lowest activity since the beginning of the Twentieth century. The current solar cycle (SC24) is so far the weakest cycle in the last 100 years. For this period, EEP events were strongest and most frequent during the transition between SC23 maximum and the following minimum (Fig. 1a). Almost 75% of all major EEP events (major=daily mean electron precipitation count rate exceeding 150 counts s−1) in the 2002–2012 period occurred between 2003 and 2006. The occurrence of solar proton events (SPEs) peaked during high solar activity (red numbers in Fig. 1a).

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.