Abstract
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)
Highlights
Coronagraph measurements provide information about the size and three-dimensional shape of coronal structures within ∼30 RS of the Sun, but further out in the solar wind, much less is known about how such large-scale structures evolve
When we examine the data for spacecraft latitude separations between 0◦ and 42◦, there are many instances where both spacecraft appear to observe very similar sectors
The Ulysses orbit is such that larger latitude separations between the spacecraft occur at smaller radial separations; the percent improvement is larger at distances less than 4 AU
Summary
Coronagraph measurements provide information about the size and three-dimensional shape of coronal structures within ∼30 RS of the Sun, but further out in the solar wind, much less is known about how such large-scale structures evolve. Elliott et al.: Latitudinal extent (2002) compared Ulysses and ACE data to solar observations to determine the source site on the Sun of the different types of solar wind We use both ACE and Ulysses data as do Neugebauer et al (2002), but we focus on the dynamics of large-scale structures. Recent work by Riley et al (2002) provides motivation for examining the dynamics of large-scale features in the inner heliosphere. They found that using constant speed mapping produces a significantly different heliospheric current sheet shape than when dynamics are included. The region from 1–5 AU is ideal for studying stream evolution and the development of corotating interaction regions
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call