SMEI Remote Sensing and the 3D Reconstruction of Corotating Heliospheric Structures

We report observations and 3D reconstructions of corotating heliospheric structures observed by the Solar Mass Ejection Imager (SMEI). Observations of the inner heliosphere have been carried out on a routine basis by SMEI since its launch in early 2003, and these have been used to measure and map the outward flow of several-hundred CMEs. Most of these observations use short-term variations of brightness from one SMEI orbit to the next (every 102 minutes) to track outward motion. The disadvantage of these orbit-to-orbit analyses is that they cannot measure features that remain stationary relative to the Sun-Earth line (or those which corotate with the Sun) and change slowly over time periods of several days. At UCSD we provide measurements of heliospheric structures relative to a long-term base and, even in these observations, there is little evidence of long-term stationary-standing density structures that corotate. By employing a kinematic model of the solar wind, we reconstruct three-dimensional (3D) solar wind structures from multiple observing lines of sight through the outward-flowing solar wind. By including interplanetary scintillation (IPS) velocity observations from STELab, Japan or from Ooty, India we can extract both the solar wind density and velocity from these analyses to compare with "ground truth" measurements from multi-point, in-situ solar wind measurements from the STEREO, SOHO, Wind, and ACE spacecraft. We define the heliospheric structures by these 3D velocity analyses, and they show that while the velocities map large regions near the ecliptic that corotate, the dense structures that front and follow these regions are far more tenuous.