R. A. Jones

Interaction between coronal mass ejections and the solar wind

[1] Observations suggest that the interplanetary extensions of coronal mass ejections (iCMEs) may be accelerated or decelerated in their passage through the solar wind. Interplanetary scintillation measurements (IPS) can detect the passage of iCMEs beyond the field of view of the Large-Angle and Spectrometric Coronagraph coronagraphs and can provide information on their velocities. The European Incoherent Scatter Radar and the Multi Element Radio Linked Interferometer Network systems, with a field of view covering 10–120 solar radii, can provide information on iCMEs in the inner regions of the solar wind. IPS observations can also provide solar wind velocity measurements ahead of the iCME, and using this information, we consider the velocity profile of a number of clearly defined iCMEs and the relationship between iCME velocities and that of the background solar wind. The results provide additional confirmation that iCMEs converge toward the velocity of the solar wind ahead of the event and that most of the resulting acceleration or deceleration occurs in the innermost regions of the solar wind.

Large-scale structure of the fast solar wind

We present the results of a comprehensive study of the fast solar wind near solar minimum conditions using interplanetary scintillation (IPS) data taken with the EISCAT system in northern Scandinavia, and a recent extremely long baseline observation using both EISCAT and MERLIN systems. The results from IPS observations suggest that the fast wind inside 100 solar radii (R-circle dot) can be represented by a two-mode model in some cases but this distinction is much less clear by in situ distances beyond 1 astronomical unit (215 R-circle dot). Two distinct fast streams are seen in the extremely long baseline IPS observation; comparison of the IPS line of sight with a synoptic map of white light indicates the faster mode overlies the polar crown and the slower fast mode overlies an equatorial extension of the polar coronal hole.

Dual-frequency interplanetary scintillation observations of the solar wind

Fallows, R. A., Breen, A. R., Bisi, M. M., Jones, R. A., Wannberg, G. (2006). Dual-frequency interplanetary scintillation observations of the solar wind. Geophysical Research Letters, 33 (11), 11106.

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.