Macroscale coherence of the heliospheric current sheet: Pioneers 10 and 11 comparisons
Abstract
We use the near radial alignments of Pioneers 10 and 11 during 1974 to study the macroscale geometry of the heliospheric current sheet (HCS). The interval of near alignment gave eight analyzable cases of encounters of both spacecraft with the same HCS and one case in which the IMP and Pioneer 11 spacecraft, while nearly radially aligned, encountered the same current sheet. The degree of macroscale coherence of the HCS was judged by comparing observed solar wind speeds against solar wind speeds calculated on the bases of HCS encounter times and ideal Parker spiral geometry. The correlation coefficient between the two sets of speeds is 0.53. The difference between the calculated and observed speeds can be understood in terms of observed deviations from ideal spiral geometry in the ecliptic plane or in terms of typical corrections to the calculations from small latitudinal factors. One case, however, defies explanation in these terms. This range of behavior demonstrates that the HCS is a useful probe of heliospheric dynamics.
 Publication:

Geophysical Research Letters
 Pub Date:
 September 1994
 DOI:
 10.1029/94GL01704
 Bibcode:
 1994GeoRL..21.2075S
 Keywords:

 Coronal Holes;
 Current Sheets;
 Helical Flow;
 Heliosphere;
 Transit Time;
 Pioneer Space Probes;
 Solar Wind Velocity;
 Spectrum Analysis;
 Velocity Measurement;
 Solar Physics;
 Interplanetary Physics: General or miscellaneous;
 Interplanetary Physics: Solar wind plasma;
 Interplanetary Physics: Interplanetary magnetic fields;
 Space Plasma Physics: General or miscellaneous