Relation between solar-wind structure and solar-wind rotational and tangential discontinuities

Solar wind plasma and magnetic field data were used to identify rotational and tangential discontinuities during the first 40 days of the flight of Mariner 5. Of the 40 rotational discontinuities found, 36 were clustered in three distinct 3- to 6-day intervals. These three intervals were characterized by high solar wind bulk velocities, high magnetic field magnitudes, low densities, high correlation between velocity and magnetic field changes, and the presence of smooth Alfvén waves. The rotational discontinuities had magnetic field changes that were generally close to the direction of magnetic field changes for smooth Alfvén waves. Although the primary component of these changes was perpendicular to the equatorial plane for both, the radial component for the discontinuities was generally larger. The normals to the tangential discontinuity surfaces strongly preferred a direction near the ecliptic plane and perpendicular to the spiral field direction. For quiet plasma streams there is evidence suggesting that the least likely directions of changes in B and V near the discontinuity tended to be distributed along the normal to the discontinuity surface. In disturbed plasma streams the magnetic field also behaved as it did in the quiet stream case, whereas the velocity confinement was only true at the discontinuity and did not persist away from the discontinuity. The least likely directions of change for the magnetic field and velocity near the discontinuities were different from those found overall for the 40 days studied. An examination of the qualitative features of fast and slow plasma streams revealed differences in the behavior of the magnetic field and velocity and their fluctuations, the field magnitude, and the density. It is suggested that these differences are correlated with the occurrence of rotational discontinuities.