The three‐dimensional solar wind around solar maximum

Ulysses is now completing its second solar polar orbit, dropping back down in latitude as the Sun passes through its post‐maximum phase of the solar cycle. A mid‐sized circumpolar coronal hole that formed around solar maximum in the northern hemisphere has persisted and produced a highly inclined CIR, which was observed from ∼70°N down to ∼30°N. We find that the speed maxima in the high‐speed streams follow the same slow drop in speed with decreasing latitude observed in the large polar coronal holes around solar minimum. These results suggest a solar wind acceleration effect that is related to heliolatitude or solar rotation. We also find that the solar wind dynamic pressure is significantly lower in the post‐maximum phase of this solar cycle than during the previous one, indicating that while the heliosphere is larger than near solar minimum, it should be smaller than during or after the previous maximum.

[1]  P. Gazis,et al.  Solar cycle changes in coronal holes and space weather cycles , 2002 .

[2]  J. Steinberg,et al.  CMEs at High Northern Latitudes During Solar Maximum: Ulysses and SOHO Correlated Observations , 2003 .

[3]  W. Feldman,et al.  Ulysses observations of opposed tilts of solar wind corotating interaction regions in the northern and southern solar hemispheres , 1995 .

[4]  W. Feldman,et al.  The northern edge of the band of solar wind variability: Ulysses at ∼4.5 AU , 1997 .

[5]  J. Gosling.  COROTATING AND TRANSIENT SOLAR WIND FLOWS IN THREE DIMENSIONS , 1996 .

[6]  R. Skoug,et al.  Ulysses' second fast‐latitude scan: Complexity near solar maximum and the reformation of polar coronal holes , 2002 .

[7]  David J. McComas,et al.  The Ulysses solar wind plasma experiment , 1992 .

[8]  J. Richardson,et al.  The solar wind: from solar minimum to solar maximum , 2001 .

[9]  G. Zank,et al.  Interaction of a nonuniform solar wind with the local interstellar medium , 1996 .

[10]  D. Mccomas,et al.  Solar wind from high‐latitude coronal holes at solar maximum , 2002 .

[11]  David J. McComas,et al.  Ulysses' return to the slow solar wind , 1998 .

[12]  J. Phillips,et al.  A new class of forward‐reverse shock pairs in the solar wind , 1994 .

[13]  C. M. Hammond,et al.  ULYSSES solar wind plasma observations from peak southerly latitude through perihelion and beyond , 1995 .

[14]  Edward J. Smith,et al.  Sources of the solar wind at solar activity maximum , 2002 .

[15]  B. Barraclough,et al.  Solar wind observations over Ulysses' first full polar orbit , 2000 .

[16]  D. Mccomas,et al.  Ulysses in the south polar cap at solar maximum: Heliospheric magnetic field , 2001 .

[17]  J. F. Mckenzie,et al.  The southern high-speed stream: results from the SWICS instrument on Ulysses. , 1995, Science.