Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation 1Department of Earth and Space Science and Engineering, York University, Toronto, Ontario, Canada
31 May 2011
2Canadian Space Agency, St.-Hubert, Quebec, Canada
3Sodankylä Geophysical Laboratory, University of Oulu, Oulu, Finland
Received: 05 October 2010 – Published in Atmos. Chem. Phys. Discuss.: 25 October 2010 Abstract. The impact of NOx and HOx production by three types
of energetic particle precipitation (EPP), auroral zone medium and high
energy electrons, solar proton events and galactic cosmic rays on the middle
atmosphere is examined using a chemistry climate model. This process study
uses ensemble simulations forced by transient EPP derived from observations
with one-year repeating sea surface temperatures and fixed chemical boundary
conditions for cases with and without solar cycle in
irradiance. Our model results show a wintertime polar stratosphere ozone
reduction of between 3 and 10 % in agreement with previous studies. EPP is
found to modulate the radiative solar cycle effect in the middle atmosphere
in a significant way, bringing temperature and ozone variations closer to
observed patterns. The Southern Hemisphere polar vortex undergoes an
intensification from solar minimum to solar maximum instead of a weakening.
This changes the solar cycle variation of the Brewer-Dobson circulation, with
a weakening during solar maxima compared to solar minima. In response, the
tropical tropopause temperature manifests a statistically significant solar
cycle variation resulting in about 4 % more water vapour transported into the
lower tropical stratosphere during solar maxima compared to solar minima.
This has implications for surface temperature variation due to the associated
change in radiative forcing.
Revised: 29 April 2011 – Accepted: 11 May 2011 – Published: 31 May 2011
Citation: Semeniuk, K., Fomichev, V. I., McConnell, J. C., Fu, C., Melo, S. M. L., and Usoskin, I. G.: Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation, Atmos. Chem. Phys., 11, 5045-5077, doi:10.5194/acp-11-5045-2011, 2011.