EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Dunlop et al. 2002
Dunlop, M.W., Balogh, A. and Glassmeier, K.-H. (2002). Four-point Cluster application of magnetic field analysis tools: The discontinuity analyzer. Journal of Geophysical Research 107: doi: 10.1029/2001JA005089. issn: 0148-0227.

The Cluster spacecraft have collected 3-D information on magnetic field structures at small to medium scales (100--1000 km) in the Earth's dayside magnetosphere, magnetosheath, and near solar wind. We focus here on the first application of the discontinuity analyzer analysis technique (determination of the geometry and motion of magnetic discontinuities, using interspacecraft timing and variance information) for the case of boundaries that are planar over the four-spacecraft array. This multipoint technique uses minimum variance of the magnetic field to determine the boundary normals at each spacecraft. Identification of the four spacecraft crossings requires accurate timing of encounters at each spacecraft, which depends on key features in each time series being stationary in the frame of the boundary. The technique is tested for selected boundary crossing events (magnetopause and bow shock, and one TD in the magnetosheath), for which the independently determined normals are closely (~1--2¿) colinear. Closely aligned normals, on spatial scales of ~600--1000 km, were found for most crossings studied. For such a planar geometry, the motion can be determined unambiguously and shows that significant acceleration (up to ~10 km s-2) of the boundary over the spacecraft is nearly always present. This has the consequence that previous estimates of boundary scales, based on constant motion between two spacecraft, may be in error by factors of two or three and that implied variations in boundary thickness could therefore be predominantly due to variations in speed. We comment on the error introduced through assumptions of constant motion.

BACKGROUND DATA FILES

Abstract

Keywords
Magnetospheric Physics, Magnetopause, cusp, and boundary layers, Magnetospheric Physics, Instruments and techniques, Magnetospheric Physics, Solar wind/magnetosphere interactions
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit