Heliospheric tomography using interplanetary scintillation observations

Abstract We have produced a Computer Assisted Tomography (CAT) program that optimizes a three-dimensional model to fit observational data. We have used this program with interplanetary scintillation data from Nagoya, Japan and Cambridge, England. The program iterates to a least-squares solution fit of observed data using solar rotation and solar wind motion to provide perspective views of each point in space accessible to the observations. We plot the optimized model as Carrington maps in velocity, V , and density, N e , for the two data sets with resolutions of ten degrees in heliographic longitude and latitude. High velocities modeled at the solar surface for individual rotations trace the outlines of coronal holes (including polar ones) observed in Yohkoh Soft X-ray Telescope (SXT) observations. Regions of slow velocity generally map to bright regions in SXT data. Regions of high density modeled from the Cambridge scintillation level data generally show a high correlation with regions of high solar activity observed as bright in Yohkoh SXT observations.