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Dependence of velocity fluctuations on solar wind speeds: A simple analysis with IPS methodA number of theoretical works have suggested that MHD plasma fluctuations in solar winds should play an important role particularly in the acceleration of high speed winds inside or near 0.1 AU from the sun. Since velocity fluctuations in solar winds are expected to be caused by the MHD plasma fluctuations, measurements of the velocity fluctuations give clues to reveal the acceleration process of solar winds. We made interplanetary scintillation (IPS) observations at the region out of 0.1 AU to investigate dependence of velocity fluctuations on flow speeds. For evaluating the velocity fluctuation of a flow, we selected the IPS data-set acquired at 2 separate antennas which located in the projected flow direction onto the baseline plane, and tried to compare skewness of the observed cross correlation function(CCF) with skewness of modeled CCFs in which velocity fluctuations were parametrized. The integration effect of IPS along a ray path was also taken into account in the estimation of modeled CCFs. Although this analysis method is significant to derive only parallel fluctuation components to the flow directions, preliminary analyses show following results: (1) High speed winds (Vsw greater than or equal to 500 km/s out of 0.3 AU) indicate enhancement of velocity fluctuations near 0.1 AU; and (2) Low speed winds (Vsw less than or equal to 400 Km/s out of 0.3 AU) indicate small velocity fluctuations at any distances.
Document ID
19960021356
Acquisition Source
Jet Propulsion Laboratory
Document Type
Conference Paper
Authors
Misawa, H.
(Nagoya Univ. Toyokawa, Japan)
Kojima, M.
(Nagoya Univ. Toyokawa, Japan)
Date Acquired
August 17, 2013
Publication Date
June 30, 1995
Subject Category
Solar Physics
Accession Number
96N24752
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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