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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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