HR: 1340h
AN: SA23A-1131    [Abstracts]
TI: The Middle Atmosphere and Energetic Particle Precipitation - response in the Canadian Middle Atmosphere Model
AU: Semeniuk, K
EM: kirill@nimbus.yorku.ca
AF: Centre for research in Earth and Space Science, York University 4700 Keele Street, Toronto, ON M3J 1P3, Canada
AU: Fu, C
EM: Chao.Fu@space.gc.ca
AF: Canadian Space Agency, 6767, Route de l'Aéroport, St Hubert, QC J3Y 8Y9, Canada
AU: Fomichev, V
EM: victor@nimbus.yorku.ca
AF: Centre for research in Earth and Space Science, York University 4700 Keele Street, Toronto, ON M3J 1P3, Canada
AU: * McConnell, J C
EM: jcmcc@yorku.ca
AF: Centre for research in Earth and Space Science, York University 4700 Keele Street, Toronto, ON M3J 1P3, Canada
AU: Melo, S
EM: Stella.Melo@space.gc.ca
AF: Canadian Space Agency, 6767, Route de l'Aéroport, St Hubert, QC J3Y 8Y9, Canada
AB: Abstract: Penetration of ionizing particles from space can substantially modify the composition of the middle atmosphere, its temperature distribution and dynamics. Persistent auroral precipitation affects primarily the upper polar mesosphere but under the right transport conditions it can influence the stratosphere. Galactic cosmic rays and strong but sporadic solar protons can penetrate deeper into the stratosphere. The effect of ionizing particle precipitation varies in response to changes in solar activity and the terrestrial magnetic field. To investigate the response of the middle atmosphere to the energetic particles precipitating from the space and build a hierarchy of different forcing mechanisms, the Canadian Middle Atmosphere Model (CMAM) has been used in several multi-year experiments. Observed daily electron and proton fluxes from 1979 to 2006 and parameterized galactic cosmic rays have been introduced in the model to obtain production rates of NOx, Ox and HOx. It has been found that auroral precipitation has a non-negligible impact on the NOy budget in the polar stratosphere with the largest impact in the southern hemisphere where the annual mean ozone loss is increased by between 5% and 15%. Sporadic solar proton events have a small long-term impact which is greatest during the solar cycle maximum. Due to their persistence, galactic cosmic rays may have a larger long-term temperature effect than solar proton events.
DE: 0342 Middle atmosphere: energy deposition (3334)
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting