Directional Discontinuities Found During Bartels Rotation 2286
Abstract
Cluster spacecraft triangulation measurements demonstrate that most, if not, all directional discontinuities (DDs) have small normal magnetic field components, consistent with tangential discontinuities (TDs). However, many of these have small total magnetic intensity jumps which render them unclassifiable by conventional two-parameters methods. In general, these DDs can occur in association with Alfvénic fluctuations. As a result, classification is not unique and it could also be that some share of the DDs belong to persistent, nondissipative rotational discontinuities (RDs) or to transient, dissipative turbulent current sheets. To move beyond individual classification, we adopt a statistical approach. With 1/3 per second magnetic field data from the ACE spacecraft from days 7 to 33 in 2001, we use an automated technique to find discontinuities individually in each of the RTN field components and then overlap them. This technique is independent of spread angle. We have found that the distance separating neighboring DDs forms a log-normal distribution. The tendency for DDs to cluster in close vicinity to each other is inconsistent with an in situ population of RDs generated by wave steepening. Widths are determined by the cross-product method and peak at 4 proton inertial lengths for DDs with spread angles exceeding 3°. The magnetic intensity jumps are mostly small and layers behave as smooth ramps. Little indication is seen of a transient character. The statistical properties appear to come from a single population which is most likely TDs. This work is performed in association with the Living With A Star focus team on Heliospheric Magnetic Fields.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFMSH53A1473V
- Keywords:
-
- 2109 Discontinuities (7811);
- 2134 Interplanetary magnetic fields;
- 7811 Discontinuities (2109)