Recreating the Three Dimensional Structure of Interplanetary Coronal Mass Ejections

With the abundance of heliospheric image data in recent years from the Solar Mass Ejection Imager (SMEI) aboard Coriolis and the Heliospheric Imagers (HIs) aboard STEREO it is of critical importance that the appearance of Interplanetary Coronal Mass Ejections (ICMEs) in these images be thoroughly understood. At large distances from the Sun, many of the standard assumptions required for producing measurements from images of Coronal Mass Ejections (CMEs) in coronagraphs do not apply. To extract meaningful physical parameters from ICME images it is necessary to consider the physics responsible for their appearance. We have developed a model based on a theory that builds up a picture of the observed ICME from the Thomson physics of a single electron, to an integrated line of sight, to a complete ICME including the consequences of its geometry relative to the observer. This has allowed us to extract the physical parameters responsible for the ICME appearance (kinematic properties and geometry) for any ICME from which reliable leading edge measurements can be made. We present the theoretical framework for the model and demonstrate its utility by discussing a single example ICME that was observed by SMEI and the HIs in November 2007. Our results indicate the model has produced a reliable convergence for this event and the extracted parameters corresponding to the structure and timing of the event observed with the heliospheric imagers and the available in-situ measurements from the STEREO and ACE spacecraft. We conclude with a discussion of the physics responsible for the evolution of this ICME.