Extreme interplanetary rotational discontinuities at 1 AU

Lepping, R. P., and C.-C. Wu

Abstract:

[1] This study is concerned with the identification and description of a special subset of four Wind interplanetary rotational discontinuities (from an earlier study of 134 directional discontinuities by Lepping et al. (2003)) with some "extreme" characteristics, in the sense that every cas has (1) an alomost planar current sheet surface, (20) a very large discontinuity angle (ω), (3) at least moderately strong normal field components (>0.8 nT), and (4) the overall set has a very broad range of transition layer thicknesses, with one being as thick as 50 R_E and another at the other extreme being 1.6 R_E, most being much thicker than usually studied. Each example has a well-determined surface normal (n) according to minimum variance analysis and corroborated via time delay checking of the discontinuity with observations at IMP 8 by employing the local surface planarity. From the variance analyses, most of these cases had unusually large ratios of intermediate-to-minimum eigenvalues (λ_I/λ_min), being on average 32 for three cases (with a fourth being much larger), indicating compact current sheet transition zones, another (the fifth) extreme property.

J. Geophys. Res., 2005