Radial and latitudinal dependencies of discontinuities in the solar wind between 0.3 and 19 AU and -80 degrees and +10 degrees

Directional discontinuities (DD) from 5 missions at 7 different locations b etween 0.3 and 19 AU and -80 degrees and +10 degrees in the 3D heliosphere are investigated during minimum, solar activity. The data are surveyed usin g the identification criteria of Burlaga (1969) (B) and Tsurutani and Smith (1979) (TS). The rate of occurrence depends linearly on the solar wind vel ocity caused by the geometric effect of investigating a larger plasma volum e if the solar wind velocity v(sw) increases. The radial dependence is prop ortional to r(-0.78) (TS criterion) and r(-1.28) (B criterion), respectivel y. This dependence is not only due to an increasing miss rate with increasi ng distance. The DDs must be unstable or some other physical effect must ex ist. After normalization of the daily rates to 400 km/s and 1 AU, no depend ence on heliographic latitude or on solar wind structures is observable. Th is means that the DDs are uniformly distributed on a spherical shell. Norma lizezd 64 DD per day are identified with both criteria. But large variation s of the daily rate still occur, indicating that other influences must exis t. The ratio of the rates of rotational (RDs) and tangential discontinuitie s (TDs) depends on the solar wind structures. In high speed streams, relati vely more RDs exist than in low speed streams. In the inner heliosphere (r< 10 AU), no radial or latitudinal dependence of the portions of the DD types occur. 55% clear RDs, 10% clear TDs and 33% EDs (either discontinuities) a re observed, but the portions differ with regard to the criteria used. In t he middle heliosphere (10 AU < r < 40 AU), the DD types are more uniformly distributed. The distribution of the directional change <omega> over the tr ansition evolves to an increase of smaller omega with increasing distance f rom the sun. The evolution is yielded by the anisotropic RDs with small ome ga. The spatial thickness d(km) in kilometers increases with distance. The thickness d(rg) normalized to the proton gyro radius decreases by a factor of 50 between 0.3 and 19 AU, from 201.3 r(g) down to 4.3 r(g). In the middl e heliosphere, the orientation of the normals relative to the local magneti c field is essentially uniform except for the parallel direction where no D Ds occur. This indicates that RDs propagating parallel to B play a special role. In addition, in only a few cases is [v] parallel to [B/rho], which is required by the MHD theory for RDs. The DDs have strongly enhanced values of proton gyro radius r(g) for omega similar to 90 degrees. In contrast, in the inner heliosphere, only a small increase in r(g) with omega is observe d.