Large-scale and solar-cycle variations of the solar wind

Heliocentric distance dependence of the interplanetary magnetic field

“…The Mariner 4 and 5 results were combined by Neugebauer (1975a) with those from Pioneer 10 ( Smith, 1974) to show that the total data set was consistent with an inverse-square law variation. Neugebauer pointed out that the data sets from the various spacecraft were not strictly comparable, however, with differences both in methods of analysis (see Table 1) and in coordinate systems employed.…”

“…Mariner 5 and Pioneer 6 solar rotation averages as presented by Neugebauer (1975a), plus Pioneer 10 solar rotation averages and …”

“…In the review by Neugebauer (1975a), the variation of the azimuthal component B with heliocentric distance for a composite data set was also shown.…”

“…The average value of AV during the Pioneer 10 transit to 5 AU was 38 km/sec. Figure 5 shows the most probable Pioneer 10 field angles for each solar rotation plotted as a function of heliocentric distance, together with least-squares fits to the Mariner 4 and 5 data (Smith, 1974;Neugebauer, 1975a), for the two sector directions. Also shown are the theoretical spiral angles for a constant solar wind velocity of 60 kin/sec.…”

“…Recent reviews of this subject have been concerned either with a broad coverage of topics related to the magnetic field alone (e.g., Schatten, 1971;Burlaga and Ness, 1976) or have treated the more general subject of large-scale solar wind variations (Neugebauer, 1975a). Smith (1974) In general, two methods of deriving radial gradients can be used 0…”