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Search for fine scale structures in high latitude solar windAbout 25 years ago, E. Parker suggested that, as a consequence of the inhomogeneous structure of the corona, the solar wind might consist of adjacent structures with different physical conditions. Since that suggestion was made, the solar wind plasma characteristics have been measured in situ through many experiments, but little has been done to check whether the solar wind shows any evidence for fine scale structures, and, in the affirmative, how far from the Sun these structures persist. A previous work on this subject, by Thieme, Marsch and Schwenn (1990), based on Helios data, lead these authors to claim that the solar wind, between 0.3 and 1 AU, is inhomogeneous on a scale consistent with the hypothesis that the plume-interplume plasmas, at those distances, still retain their identity. In this work we present preliminary results from an investigation of the solar wind fine structure from Ulysses high latitude observations. To this end, we have analyzed data over several months, during 1994, at times well after Ulysses's last encounter with the Heliospheric Current Sheet, when the spacecraft was at latitudes above 50 degrees. These data refer to high speed wind coming from southern polar coronal holes and are best suited for plume-interplume identification. We have performed a power spectra analysis of typical plasma parameters, to test whether the wind plasma consist of two distinct plasma populations. We also examined data to check whether there is any evidence for an horizontal pressure balance over the hypothesized distinct structures. Our results are discussed and compared with previous findings.
Document ID
19960021461
Acquisition Source
Jet Propulsion Laboratory
Document Type
Conference Paper
Authors
Livi, S.
(Max-Planck-Inst. fuer Aeronomie Katlenburg-Lindau, Germany)
Parenti, S.
(Florence Univ. Italy)
Poletto, G.
(Osservatorio Astrofisico di Arcetri Florence, Italy)
Date Acquired
August 17, 2013
Publication Date
June 30, 1995
Subject Category
Solar Physics
Accession Number
96N24857
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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