title: Missing driver in the Sun-Earth connection from energetic electron precipitation impacts mesospheric ozone.
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.
authors.affiliation: Earth Observation, Finnish Meteorological Institute, PO Box 503 (Erik Palménin aukio 1), Helsinki FI-00101, Finland.
authors.forename: M E
authors.initials: ME
authors.lastname: Andersson
authors.affiliation: Earth Observation, Finnish Meteorological Institute, PO Box 503 (Erik Palménin aukio 1), Helsinki FI-00101, Finland.
authors.forename: P T
authors.initials: PT
authors.lastname: Verronen
authors.affiliation: Department of Physics, University of Otago, PO Box 56, Dunedin 9016, New Zealand.
authors.forename: C J
authors.initials: CJ
authors.lastname: Rodger
authors.affiliation: British Antarctic Survey (NERC), High Cross, Madingley Road, Cambridge CB3 0ET, UK.
authors.forename: M A
authors.initials: MA
authors.lastname: Clilverd
authors.affiliation: Earth Observation, Finnish Meteorological Institute, PO Box 503 (Erik Palménin aukio 1), Helsinki FI-00101, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Seppälä