Comparison of the extent and mass of CME events in the interplanetary medium using IPS and SMEI Thomson scattering observations

The Solar-Terrestrial Environment Laboratory (STELab), Japan, interplanetary scintillation (IPS) g-level and velocity measurements can be used to give the extent of CME disturbances in the interplanetary medium arising from the scattering of the radio waves from distant point-like natural sources through the intervening medium. In addition, white-light Thomson-scattering observations from the Solar Mass Ejection Imager (SMEI) have recorded the inner heliospheric response to several hundred CMEs. The work described here compares and details the difference in three-dimensional (3D) reconstructions for these two data sets for the well-observed 28 October 2003 halo CME seen in LASCO; this passed Earth on 29 October in the SMEI data at the same elongations as IPS g-level observations. The SMEI data analysis employs a 3D tomographic reconstruction technique that obtains perspective views from outward-flowing solar wind as observed from Earth, iteratively fitting a kinematic solar wind density model, and when av...