Abstract
Abstract. The interaction of the solar wind with the Earth magnetosphere generates a broad variety of plasma waves through different mechanisms. The four Cluster spacecraft allow one to determine the regions where these waves are generated and their propagation directions. One of the tools which takes full advantage of the multi-point capabilities of the Cluster mission is the wave telescope technique which provides the wave vector using a plane wave representation. In order to determine the distance to the wave sources, the source locator – a generalization of the wave telescope to spherical waves – has been recently developed. We are applying the source locator to magnetic field data from a typical traversal of Cluster from the cusp region and the outer magnetosphere into the magnetosheath and the near Earth solar wind. We find a high concentration of low frequency wave sources in the electron foreshock and in the cusp region. To a lower extent, low frequency wave sources are also found in other magnetospheric regions.
Highlights
Numerous studies have been dedicated to the origin and nature of plasma waves in the magnetosheath and its adjacent regions. Song et al (1990, 1992a,b) showed evidence of a standing slow mode wave in front of the magnetopause over which higher frequency mirror modes convected with the magnetosheath flow are superposed. Schwartz et al (1996) gave a comprehensive overview of low frequency waves in the magnetosheath, pointing out the difficulties and complications faced by wave mode identification
In the middle magnetosheath they find orthogonal propagating, linear polarized waves, interpreted as mirror modes which are convected with the plasma flow into the inner magnetosheath region where they coexist with the slow mode
The enhancement of the low energy (≈0.1 keV) electrons density seen in the PEACE (Johnstone et al, 1997) data, the decrease in the energy of the main ion population measured by CIS (Reme et al, 2001), as well as the small decrease in the magnetic field amplitude visible in the Flux Gate Magnetometer (FGM) data around 03:10 indicate the cusp traversal
Summary
It is the aim of this work to systematically study the spatial distribution of wave sources along a magnetosheath crossing by Cluster. One of the most suitable tools for this task is the source locator (Constantinescu et al, 2006) which is the generalization of the wave telescope/k-filtering technique (Pincon and Lefeuvre, 1991; Lefeuvre and Pincon, 1992; Motschmann et al, 1995; Glassmeier et al, 2001; Sahraoui et al, 2003) to spherical waves. Published by Copernicus Publications on behalf of the European Geosciences Union.
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