This collaborative research team will investigate the evolution of energy spectra, time-intensity profiles, and charged particle flows along and across the interplanetary magnetic field in co-rotating interaction regions (CIRs) observed during solar cycles 22 and 23. They will use measurements of energetic particles, magnetic fields, and solar wind plasma obtained by the ACE, Wind, and STEREO spacecraft to study these CIR events. This team will also develop a new theoretical model, based on their existing 'Particle Acceleration and Transport in the Heliosphere' (PATH) numerical code, in order to study the time-dependent acceleration and transport of particles associated with CIRs, as well as to probe the 3D structure of CIRs and the evolution of magnetic connections between an observer at Earth and remote CIR locations beyond Earth orbit.
Understanding the properties of solar energetic particle (SEP) events associated with CIRs remains an outstanding problem for the scientific community. This study will yield new information about the 3D structure of CIRs and the configuration of the interplanetary magnetic field, both of which are crucial for the development of future global heliospheric models, which are in turn important for space weather forecasting.
Research results will be presented to the broader community at scientific meetings and at smaller workshops where student participation is encouraged. The team will also publish findings via peer-reviewed journals and web-based monthly electronic newsletters. In this project, several graduate and undergraduate students will be supported at the University of Alabama at Huntsville (UAH) and at the University of Texas at San Antonio (UTSA). This project will integrate and synergize existing research programs at UAH, the Southwest Research Institute (SwRI) in San Antonio, and the Johns Hopkins University's Applied Physics Laboratory (JHU/APL).
This outcome report is for the period of June 1st to October 31st, 2013. This was a 6-month no-cost extension period. During this period we completed perhaps the most important study of the grant, submitted our finding to ApJ and revised our paper and had it accepted. The paper was titled "Observation of Energetic particles between a pair of Corotating Interaction Regions" and the authors are Z. Wu, Y. Chen, G. Li (corresponding author), L. L. Zhao, R. W. Ebert, M. I. Desai, G. M. Mason, B. Lavraud, L. Zhao, Y. C.-M. Liu, F. Guo, C. L. Tang, E. Landi, J.Sauvaud, ApJ, accepted. In this paper, based on the observation of energetic particles at a CIR pair, together with superthermal electron observations and magnetic field observations, we showed that a large scale U-shape magnetic field disconnected from the Sun may exist. Large-scale and continuous magnetic reconnection that occur at high corona has been argued by some workers in the field of space plasma physics for some time. One consequence of these magnetic reconnection is the existence of disconnected magnetic field from the Sun. While it has been proposed for sometime, observational confirmation of such disconnected fields are difficult, if not impossible. Our paper therefore, provides the FIRST evidence of the existence of such large scale magnetic field reconnection. We believe it will have a tremendous impact on heliospheric researches.
