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Ann. Geophys., 21, 1331-1339, 2003
www.ann-geophys.net/21/1331/2003/
© European Geosciences Union 2003
Latitudinal extent of large-scale structures in the solar wind
H. A. Elliott1, D. J. McComas1, and P. Riley2
1Southwest Research Institute, San Antonio, Texas, USA
2Science Applications International Corporation,San Diego, California, USA
Abstract. Comparison of solar wind
observations from the ACE spacecraft, in the ecliptic plane at ~ 1 AU, and the
Ulysses spacecraft as it orbits over the Sun’s poles, provides valuable
information about the latitudinal extent and variation of solar wind structures
in the heliosphere. While qualitative comparisons can be made using average
properties observed at these two locations, the comparison of specific,
individual structures requires a procedure to determine if a given structure
has been observed by both spacecraft. We use a 1-D hydrodynamic code to
propagate ACE plasma measurements out to the distance of Ulysses and adjust for
the differing longitudes of the ACE and Ulysses spacecraft. In addition to
comparing the plasma parameters and their characteristic profiles, we examine
suprathermal electron measurements and magnetic field polarity to help
determine if the same features are encountered at both ACE and Ulysses. The He
I l 1083 nm coronal hole maps are examined to
understand the global structure of the Sun during the time of our heliospheric
measurements. We find that the same features are frequently observed when both
spacecraft are near the ecliptic plane. Stream structures derived from smaller
coronal holes during the rising phase of solar cycle 23 persists over 20°–30°
in heliolatitude, consistent with their spatial scales back at the Sun.
Key words. Interplanetary physics
(solar wind plasma)
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