Determining the azimuthal properties of coronal mass ejections from multi-spacecraft remote-sensing observations with stereo secchi

摘要

We discuss how simultaneous observations by multiple heliospheric imagers canprovide some important information about the azimuthal properties of CoronalMass Ejections (CMEs) in the heliosphere. We propose two simple models of CMEgeometry that can be used to derive information about the azimuthal deflectionand the azimuthal expansion of CMEs from SECCHI/HI observations. We apply thesetwo models to four CMEs well-observed by both STEREO spacecraft during the year2008. We find that in three cases, the joint STEREO-A and B observations areconsistent with CMEs moving radially outward. In some cases, we are able toderive the azimuthal cross-section of the CME fronts, and we are able tomeasure the deviation from self-similar evolution. The results from thisanalysis show the importance of having multiple satellites dedicated to spaceweather forecasting, for example in orbits at the Lagrangian L4 and L5 points.