Modeling Particle Acceleration and Transport at CIRs

Monday, 15 December 2014
Gang Li1, Lulu Zhao1, Robert W Ebert2, Mihir Indrajit Desai2, Maher A Dayeh2, Glenn M Mason3, Yao Chen4 and Zhao Wu4, (1)University of Alabama in Huntsville, Huntsville, AL, United States, (2)Southwest Research Institute, San Antonio, TX, United States, (3)JHU / APL, Laurel, MD, United States, (4)Shandong University at Weihai, Weihai, China
CIRs are a major site for particle acceleration during solar minimum. Earlier Ulysses observations have found that particles can be accelerated at both the forward and the reverse shocks that often form at a few AUs. The accelerated particles then propagate back to the Earth along Parker's field line. Theoretical calculations predicted a modulation of the spectrum at low energies, qualitatively agreed with obsevations at 1 AU. However, this picture was recently challenged by STEREO observations, where local accelerations near 1 AU were inferred in many events. In this work, we perform a detailed numerical calculation to study particle acceleration and transport in one CIR event which was observed by both ACE and STEREO spacecraft. We obtain particle currents at different heliocentric distances and different longitudes, as well as particle anisotropy. These values are compared with observations and the implication on the acceleration site and the interplanetary turbulence spectrum is discussed.