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Paper: Global Observations of Evolving 3D Solar Wind Structure
Volume: 454, The 3rd Hinode Science Meeting
Page: 413
Authors: Tokumaru, M.; Fujiki, K.; Itoh, H.; Iju, T.; Kojima, M.
Abstract: Interplanetary scintillation (IPS) and Thomson scattered whitelight serve as effective tools to obtain a global view of the evolving solar wind structure, which is hardly accessible to in situ measurements using a limited number of spacecraft. This capability has been greatly enhanced owing to the use of the computer-assisted tomography (CAT) method. From a comparison between IPS reconstructions and photospheric magnetic field observations, we have identified the solar wind sources, which are consistent with plasma outflows observed by Hinode. We have also found a coronal parameter which is closely related to the terminal wind speed, and this result show excellent agreement with the nonlinear Alfven-wave-driven solar wind model. Our IPS observations over three cycles have revealed that the global distribution of solar wind speeds changes systematically depending on the solar activity. An excellent correlation between fast/slow wind areas and polar magnetic fields is demonstrated here. The important point to note is that the solar wind speed distribution for the current minimum differs significantly from that for the previous minimum. This difference is considered a consequence of weaker polar fields in the current minimum. Rapid evolution of the 3D solar wind structure associated with CMEs has been investigated from the combined analysis of IPS and whitelight observations. The results reveal global features of interplanetary CMEs and a drastic change in the expansion speed between the Sun and Earth orbit, suggesting important implications for the propagation dynamics of CMEs in the solar wind.
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