- Conference date: 5-9 Oct 1998
- Location: Nantucket, Massachusetts (USA)
Simultaneous interplanetary scintillation (IPS) observations at 2 and 8 GHz with the Kashima radio telescope are used to study the radial profile of the solar wind speed near the sun; in the distance range between 10 and 80 solar radii The solar wind speed has been estimated from Kashima IPS data with the co-spectrum method. These speed data are compared with K-corona brightness data taken at from the Mauna Loa coronameter. The inverse relation between wind speed and K-corona brightness is revealed from this comparison, and better correlation is found for large distances. Derived velocities are sorted by the K-corona brightness to obtain the radial variation unaffected by the latitudinal/longitudinal movement of the line-of-sight. The radial profile of the wind speed from the bright K-corona region shows that the solar wind reaches the terminal speed of about 400 km/s by and this terminal speed corresponds to the slow wind. As for the speed profile from the dark K-corona region, the terminal speed is about 700–800 km/s, which is consistent with the fast wind. A velocity increase is found between 10 and in the dark K-corona data, although further study to confirm this is needed. The effect due to the non-radial expansion of the solar wind near the sun is examined from the calculation of the coronal magnetic field with the potential field model. As result, no significant improvement in the radial profile is obtained after the consideration of the non-radial expansion effect. This suggests that the radial projection is a better mapping method for our IPS observations than the non-radial projection.
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