Ground-based measurements of interplanetary scintillation (IPS) have been used to study the solar wind for many years, but interpretation of the results has always been rendered more difficult by uncertainty about the electron density distribution along the extended line-of-sight from radio source to antenna. This has been particularly marked in the case of Earth-directed coronal mass ejections (CMEs). The launch of the STEREO spacecraft, with its Heliospheric Imager (HI) instruments,provides us with the first detailed view of structures in the Sun-Earthline, revealing the motion of large-scale density structures, and greatly reducing the uncertainties in interpreting IPS observations of the speeds of small-scale irregularities embedded within the larger structures. In this poster we present results from a co-ordinated programme of measurements which brings together STEREO HI and two different IPS experiments. We consider two events, one from 2005 in which we use a combination of long-baseline IPS measurements from EISCAT and MERLIN, tomographically-reconstructed 3D density distributions from STELab IPS observations, and SOHO EIT and LASCO images to track the development of an Earth-directed CME. We discuss the remaining uncertainties in this approach and the ways in which STEREO HI images would have assisted with the analysis. In the second event we combine STEREO HI observations of structures in the solar wind with IPS measurements of solar wind speed from EISCAT and MERLIN and tomographicreconstructions of 3D structure. We discuss the results and present suggestions for future co-ordinated campaigns.
|Cyhoeddwyd - 01 Rhag 2007