G. Siscoe et D. Intriligator, 3 VIEWS OF 2 GIANT STREAMS - ALIGNED OBSERVATIONS AT 1 AU, 4.6 AU, AND 5.9 AU, Geophysical research letters, 20(20), 1993, pp. 2267-2270
A close radial alignment of the IMP and Pioneers 10 and 11 spacecraft
in 1974 allows a nearly unambiguous , empirical study of the radial ev
olution of the interaction regions of two contrasting weak and strong,
giant streams. The study confirms the main aspects of the standard mo
del of corotating interaction regions: an expanding and strengthening
pair of forward-reverse shocks sandwich a stream interface. It adds th
e following concepts: stream group speed--the speed at the stream inte
rface tends to remain constant with distance; corotating stream comple
xes--interaction regions can include features like noncompressive dens
ity enhancements and streamer belts; secondary interfaces--a possible
precursor to the reverse shock; and emerging stream interfaces--one em
erged between 1 AU and 4.6 AU. The study uses the conservation specifi
c entropy to correlate features between spacecraft.