3-D Perspectives of Solar Activity Using Modern Solar and Heliospheric Imaging

Rouillard Alexis, arouillard@irap.omp.eu, Institut De Recherche En Astrophysique et Planetologie

Abstract
3-D perspectives of solar activity can be obtained from a wide range of in-situ measurements and remote-sensing techniques. Extreme ultraviolet (EUV) or white-light imaging sensed from several vantage points can be used to infer the 3-D geometry of a variety of coronal and solar wind features. We will show that the twin STEREO spacecraft launched in 2006 offer multi-point observations of the corotating solar wind and provide direct information on its 3-D structure and variability. Other sources of valuable 3-D remote-sensing observations are obtained by applying tomographic techniques to Earth-based observations of interplanetary scintillations and white-light observations obtained by the Solar Mass Ejection Imager (SMEI) launched in 2003. All these observations provide an uninterrupted coverage of plasma streaming radially outward from the Sun to 1AU and beyond, thereby allowing remote-sensing observations to be combined with in-situ measurements. They show that the spinning Sun ejects continually small- and large-scale transients that, for a fixed source region, will be distributed along a spiral rooted in that source region. These transients often have twisted magnetic fields that can extend over a wide range of scales and that may transport a significant amount of total magnetic flux. The launch of the Solar Dynamics Observatory (SDO) during the recent high solar-activity period has provided a third eye with unprecedented high-cadence and high-resolution observations. These latter observations combined with STEREO imaging permit very detailed analyses of the eruption of Coronal Mass Ejections (CMEs) and the 3-D extent of CME-driven pressure waves. Remote sensing of pressure waves launched in the near-CME environment can be compared with in-situ measurements of the onset, abundance ratios and flux of energetic particles providing critical information on the 3-D extent of the acceleration and transport of energetic particles near the Sun and in the inner heliosphere.