The overarching goal of this project is to achieve full understanding of evolution of coronal mass ejections (CMEs) in the interplanetary space  in order to make effective prediction of their arrival  at the Earth. This project has yielded several important scientific results toward achieving this goal. (1) An outstanding question concerning interplanetary coronal mass ejections (ICMEs) is whether all ICMEs have a magnetic flux rope Structure. We test this hypothesis by studying two different ICMEs, one having a magnetic cloud (MC) showing smooth rotation of magnetic field lines and the other not, but both ICMEs had similar origin on the Sun. We find that the difference in the in-situ observation was mainly caused by the geometric selection effect. We infer that all ICMEs have a flux rope origin.  (2) Through a detailed study of a Sun-Earth connection event, we find that the propagation of the CME ejecta front and the shock front is not completely dependent upon one another, but can each be modeled in the heliosphere with a drag model that assumes the dominant force of affecting CME evolution to be the aerodynamic drag force of the ambient solar wind. Results indicate that the CME ejecta front undergoes a more rapid deceleration than the shock front within 50 solar radii.  (3) We investigated the physical nature of halo coronal mass ejections (CMEs) based on the stereoscopic observations from the two STEREO spacecraft, Ahead and Behind, and the SOHO spacecraft. It has been widely believed that the halo appearance of a CME is caused by the geometric projection effect, i.e., a CME moves along the Sun-observer line. However, to our surprise, we find that 41 out of 62 events (66%) were observed as halo CMEs by all coronagraphs. This result suggests that a halo CME is not just a matter of the propagating direction. We conclude that the apparent width of CMEs, especially halos or partial halos is driven by the existence and the extent of the associated waves or shocks and does not represent an accurate measure of the CME ejecta size. (4) One key outcome of this project is that we have successfully demonstrated that accurate space weather prediction is possible. The method is based upon geometrical separate measurement of the CME ejecta and the sheath. The measurements are used to constrain a drag-based model, which is improved over earlier studies through a more realistic assumption, that is, the drag parameter is a function of distance instead of a constant. We further constrain the geometry of the model to determine the error introduced as a function of the deviation of the CME nose from the Sun– Earth line. Our model shows the ability to predict the CME ejecta arrival with an average error less thatn 1.5 hours, and the sheath arrival of under 3.5 hours.

      The broader impact resides in multiple fronts. We show that accurate space weather prediction is possible, giving the usage of full-coverage observations and proper theoretical models. If the accurate space weather prediction can be transitioned to operation, it will significantly mitigate the adverse space weather effects on various advanced human technological systems, including satellite operation, communication and navigation, power grids and airline flights. The project also provided opportunities for research, teaching and mentoring in science areas. The project supported the training of two graduate students, the professional development of one post-doc and two faculty members.  In particular, one graduate student was supported by this project for more than three years. His disseration topic, titled as “Understanding the Evolution and Propagation of Coronal Mass Ejections and Driven Shock Waves in the Interplanet...