Short- and medium-term atmospheric constituent effects of very large solar proton events C. H. Jackman1, D. R. Marsh2, F. M. Vitt2, R. R. Garcia2, E. L. Fleming1, G. J. Labow1, C. E. Randall3, M. López-Puertas4, B. Funke4, T. von Clarmann5, and G. P. Stiller5 1NASA/Goddard Space Flight Center, Greenbelt, MD, USA 2National Center for Atmospheric Research, Boulder, CO, USA 3University of Colorado, Boulder, CO, USA 4Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain 5Institut für Meteorologie und Klimaforschung, Forschungszentrum Karlsruhe and Univ. Karlsruhe, Karlsruhe, Germany
Abstract. Solar eruptions sometimes produce protons, which impact the Earth's
atmosphere. These solar proton events (SPEs) generally last a few days and
produce high energy particles that precipitate into the Earth's atmosphere.
The protons cause ionization and dissociation processes that ultimately lead
to an enhancement of odd-hydrogen and odd-nitrogen in the polar cap regions
(>60° geomagnetic latitude). We have used the Whole Atmosphere
Community Climate Model (WACCM3) to study the atmospheric impact of SPEs
over the period 1963–2005. The very largest SPEs were found to be the most
important and caused atmospheric effects that lasted several months
after the events. We present the short- and medium-term (days to a few
months) atmospheric influence of the four largest SPEs in the past 45 years
(August 1972; October 1989; July 2000; and October–November 2003) as
computed by WACCM3 and observed by satellite instruments. Polar
mesospheric NOx (NO+NO2) increased by over 50 ppbv
and mesospheric ozone decreased by over 30% during these very large
SPEs. Changes in HNO3, N2O5, ClONO2, HOCl,
and ClO were indirectly caused by the very large SPEs
in October–November 2003, were simulated by WACCM3, and
previously measured by Envisat Michelson Interferometer for Passive
Atmospheric Sounding (MIPAS).
WACCM3 output was also represented by sampling with the
MIPAS averaging kernel for a more valid comparison.
Although qualitatively similar,
there are discrepancies between the model and measurement with WACCM3
predicted HNO3 and ClONO2 enhancements being smaller than measured
and N2O5 enhancements being larger than measured.
The HOCl enhancements were fairly similar in amounts and temporal
variation in WACCM3 and MIPAS.
WACCM3 simulated ClO decreases below 50 km, whereas MIPAS
mainly observed increases, a very perplexing difference.
Upper stratospheric and lower mesospheric
NOx increased by over 10 ppbv and was transported during polar night
down to the middle stratosphere in several weeks past the SPE. The WACCM3
simulations confirmed the SH HALOE observations of enhanced NOx
in September 2000 as a result of the July 2000 SPE and the NH SAGE II
observations of enhanced NO2 in March 1990 as a result of
the October 1989 SPEs.
Citation: Jackman, C. H., Marsh, D. R., Vitt, F. M., Garcia, R. R., Fleming, E. L., Labow, G. J., Randall, C. E., López-Puertas, M., Funke, B., von Clarmann, T., and Stiller, G. P.: Short- and medium-term atmospheric constituent effects of very large solar proton events, Atmos. Chem. Phys., 8, 765-785, doi:10.5194/acp-8-765-2008, 2008.