The characteristics of the magnetopause reconnection X-line deduced from low-altitude satellite observations of cusp ions

Journal Article · Thu Dec 01 04:00:00 EST 1994 · Geophysical Research Letters

DOI:https://doi.org/10.1029/94GL02696· OSTI ID:86414

Lockwood, M; Davis, C J ^[1]; Onsager, T G ^[2]; Smith, M F ^[3]; Denig, W F ^[4]

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1. Rutherford Appleton Lab., Oxon (United Kingdom)
2. Univ. of New Hampshire, Durham, NH (United States)
3. Goddard Space Flight Center, Greenbelt, MD (United States)
4. Phillips Lab., Bedford, MA (United States)

The authors present an analysis of a {open_quotes}quasi-steady{close_quotes} cusp ion dispersion signature observed at low altitudes. They reconstruct the field-parallel part of the Cowley-D ion distribution function, injected into the open LLBL in the vicinity of the reconnection X-line. From this they find the field-parallel magnetosheath flow at the X-line was only 20 {+-} 60 km s{sup {minus}1}, placing the reconnection site close to the flow streamline which is perpendicular to the magnetosheath field. Using interplanetary data and assuming the subsolar magnetopause is in pressure balance, they derive a wealth of information about the X-line, including: the density, flow, magnetic field and Alfven speed of the magnetosheath; the magnetic shear across the X-line; the de-Hoffman Teller speed with which field lines emerge from the X-line; the magnetospheric field; and the ion transmission factor across the magnetopause. The results indicate that some heating takes place near the X-line as the ions cross the magnetopause, and that sheath densities may be reduced in a plasma depletion layer. The authors also compute the reconnection rate. Despite its quasi-steady appearance on an ion spectrogram, this cusp is found to reveal a large pulse of enhanced reconnection rate. 11 refs., 5 figs., 1 tab.

• OSTI ID: 86414
• Journal Information: Geophysical Research Letters, Journal Name: Geophysical Research Letters Journal Issue: 24 Vol. 21; ISSN GPRLAJ; ISSN 0094-8276
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DISTRIBUTION FUNCTIONS
IONS
MAGNETIC RECONNECTION
MAGNETOPAUSE
POLAR CUSP