The solar eruption of 2005 May 13 and its effects: Long-baseline interplanetary scintillation observations of the Earth-directed coronal mass ejection

Long-baseline observations of interplanetary scintillation (IPS) provide a unique source of information on solar wind speed and meridional direction across the inner regions of the solar system. We report the results of a series of coordinated IPS observations of an Earth-directed CME. A significant development in the interpretation of these data is the use of 3D tomographic reconstructions of solar wind structure derived from STELab IPS data to better constrain the analysis of extremely long baseline observations from EISCAT and MERLIN. The combination of these two approaches leads to a significantly better understanding of the interaction of the CME with the background solar wind than would be possible with either technique alone, revealing a significant rotation in the meridional flow direction of the background wind associated with the passage of the CME. The CME itself is decelerated significantly between its emergence through the corona and its arrival in the IPS ray path, with comparatively little change in speed from then until arrival at ACE.