Empirical reconstruction and long-duration tracking of the magnetospheric boundary in single- and multi-spacecraft contexts

Abstract

Abstract.The magnetospheric boundary is always moving, making it difficult to establish its structure. This paper presents a novel method for tracking the motion of the boundary, based on in-situ observations of the plasma velocity and of one or more additional observables. This method allows the moving boundary to be followed for extended periods of time (up to several hours) and aptly deals with limitations on the time resolution of the data, with measurement errors, and with occasional data gaps; it can exploit data from any number of spacecraft and any type of instrument. At the same time the method is an empirical reconstruction technique that determines the one-dimensional spatial structure of the boundary. The method is illustrated with single-and multi-spacecraft applications using data from Ampte/Irm and Cluster.

Magnetopause and Boundary Layer

“…As first suggested by Dungey (1955), the Kelvin-Helmholtz instability (KHI) may also be a mechanism for creating surface waves (Drazin and Reid, 1985). The KHI may occur when two fluids are in motion with respect to one another.…”

“…De Keyser et al (2004b) have computed an empirical reconstruction using the optimisation approach. The time resolution with which the motion of the boundary is reconstructed was 20 s. The CIS/HIA perpendicular plasma velocity v ⊥x (only on C1 and C3) is used as a proxy for boundary motion.…”

Properties of standing Kruskal-Schwarzschild-modes at the magnetopause

“…The magnetopause is located between the half spaces at x = 0 (blue surface). measured in the vicinity of the magnetopause (Paschmann et al, 1990) or the more advanced empirical reconstruction method (De Keyser et al, 2005) until the start of the five spacecraft mission THEMIS (Angelopoulos, 2008).…”

Analysis of three-spacecraft data using planar reciprocal vectors: methodological framework and spatial gradient estimation

“…The least-squares approach allows to address diverse multipoint analysis tasks such as the estimation of spatial gradients and boundary parameters (Harvey, 1998;De Keyser et al, 2005 as well as wave vectors (Vogt et al, 2008a). In the case of four spacecraft, and if no further constraints are taken into account, the homogeneous least-squares approach to spatial gradient estimation is equivalent to the reciprocal vector method that allows to write down estimators for various analysis parameters in a very transparent way (Chanteur, 1998;Chanteur and Harvey, 1998).…”