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Task 1 Project 1

What is the effect of transient solar events on the middle and lower atmosphere?

Input for this task is expected from WG3. Output will be used in task 1.3.

Co-leaders

• Irina Mironova (RU)
• Annikka Seppälä (UK/FI)

Proposed active collaborators

• studies of aerosol, water vapor response of SPE - M. Kulmala (FI), J. Kazil (GER);
• Energetic particle precipitation – P. Veronnen (Finland), M. Clilverd (UK), C. Randall (US), C. Rodger (NZ)

Introduction

Solar Energetic Particle (SEP) events – flux of the charged particles accelerated to high energies during solar flares and/or coronal mass ejections. These particles are mostly protons and heaver ions with energy ranging from a few tens of keV to GeV. Normally SEP penetrate into the upper polar atmosphere, and only during some extremely strong SEP events, called Ground Level Enhancements (GLE), energetic particles can reach the troposphere increasing the ionization rate here. Transient solar events in energetic particles on the Earth atmosphere are events with enhanced energetic particle precipitation (mostly in polar and sub-polar regions) of the duration of hours-days. This gives a unique opportunity to study a direct effect on the atmosphere in case studies.

What is the effect of transient solar events on the mesosphere and upper stratosphere?

What we know?

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What we should do?

What is the effect of transient solar events on the low stratosphere and upper troposphere?

The ultimate goal of this problem is to elaborate (probably empirical but better physics based) model of solar/geomagnetic energetic particle events on the mid- and lowatmosphere.

What we know?

One of the atmospheric characteristics that can respond to rapid changes in ionization rate is the atmospheric aerosol content. However, an increase in atmospheric aerosols can only occur in regions where both ions production and trace gases with a possibility to attach to atmospheric ions are present. The maximum ionization rate occurs in the stratospheric layers at about 15–20 km. This corresponds to the altitudes of maximum of sulphuric and nitric acid vapor concentrations and where the formation of stratospheric clouds takes place. It can be supposed that the aerosol particles can be involved in the ion induced aerosol formation scheme.

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What we should do?

Topical publications

• • Butikofer, R., Fluckiger, E., Desorgher, L., and Moser, M.: The extreme solar cosmic ray particle event on January 2005 and its influence on the radiation dose rate at aircraft altitude, Sci. Total Env., 391,177–183, 2008. • Mironova, I. A., Desorgher, L., Usoskin, I. G., Fluckiger, E. O., and Butikofer, R.: Variations of aerosol optical properties during the extreme solar event in January 2005, Geophys. Res. Lett., 35, L18610, 2008. • Randall, C. E., Harvey, V. L., Singleton, C. S., Bailey, S. M., Bernath, P. F., Codrescu, M., Nakajima, H., and Russell, J. M.: Energetic particle precipitation effects on the Southern Hemisphere stratosphere in 1992-2005, J. Geophys. Res., 112, D08 308, 2007. • Semeniuk, K., McConnell, J. C., and Jackman, C. H.: Simulation of the October- November 2003 solar proton events in the CMAM GCM: Comparison with observations, Geophys. Res. Lett., 32, L15S02, 2005. • Seppala, A., Clilverd, M. A., Rodger, C. J., Verronen, P. T., and Turunen, E.: The effects of hard-spectra solar proton events on the middle atmosphere, J. Geophys. Res., 113, A11 311, 2008.

Current projects

• ISSI Team Project: "Geospace coupling to Polar Atmosphere", 2009-2011, (leader Annika Seppälä ) • ISSI Team Project: “Study of cosmic ray influence upon atmospheric processes”, accepted for 2010-2012, (leader Irina Mironova) • EU COST Project: “Towards a sounder assessment of the impact of solar variability on the Earth’s climate”, (leader T. Dudok de Witte)

Planed Workshops, Meetings and Conferences

• During IUGG in Melbourne, Australia (28.06-7.07.2011) we plan to organize workshop on the topic of Project 1 Task 1.

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