dorsal/arxiv
View SchemaAuroral field-aligned currents by incoherent scatter plasma line observations in the E region
| Authors | Ingemar Haggstrom, Mikael Hedin, Takehiko Aso, Asta Pellinen-Wannberg, Assar Westman |
|---|---|
| Categories | |
| ArXiv ID | physics/0003019 |
| URL | https://arxiv.org/abs/physics/0003019 |
| Journal | Adv. Polar Upper Atmos. Res., 14, 2000, pp 103--121 |
Abstract
The aim of the Swedish-Japanese EISCAT campaign in February 1999 was to measure the ionospheric parameters inside and outside the auroral arcs. The ion line radar experiment was optimised to probe the E-region and lower F-region with as high a speed as possible. Two extra channels were used for the plasma line measurements covering the same altitudes, giving a total of 3 upshifted and 3 downshifted frequency bands of 25 kHz each. For most of the time the shifted channels were tuned to 3 (both), 4 (up), 5.5 (down) and 6.5 (both) MHz. Weak signals are seen whenever the radar is probing the diffuse aurora, corresponding to the relatively low plasma frequencies. At times when auroral arcs pass the radar beam, significant increases in return power are observed. Many cases with simultaneously up and down shifted plasma lines are recorded. In spite of the rather active environment, the highly optimised measurements enable investigation of the properties of the plasma lines. A modified theoretical incoherent scatter spectrum is used to explain the measurements. The general trend is an upgoing field-aligned current in the diffuse aurora, confirmed with a full fit of the combined ion and plasma line spectra. There are also cases with strong suprathermal currents indicated by large differences in signal strength between up- and downshifted plasma lines.
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"abstract": "The aim of the Swedish-Japanese EISCAT campaign in February 1999 was to\nmeasure the ionospheric parameters inside and outside the auroral arcs. The ion\nline radar experiment was optimised to probe the E-region and lower F-region\nwith as high a speed as possible. Two extra channels were used for the plasma\nline measurements covering the same altitudes, giving a total of 3 upshifted\nand 3 downshifted frequency bands of 25 kHz each. For most of the time the\nshifted channels were tuned to 3 (both), 4 (up), 5.5 (down) and 6.5 (both) MHz.\nWeak signals are seen whenever the radar is probing the diffuse aurora,\ncorresponding to the relatively low plasma frequencies. At times when auroral\narcs pass the radar beam, significant increases in return power are observed.\nMany cases with simultaneously up and down shifted plasma lines are recorded.\nIn spite of the rather active environment, the highly optimised measurements\nenable investigation of the properties of the plasma lines. A modified\ntheoretical incoherent scatter spectrum is used to explain the measurements.\nThe general trend is an upgoing field-aligned current in the diffuse aurora,\nconfirmed with a full fit of the combined ion and plasma line spectra. There\nare also cases with strong suprathermal currents indicated by large differences\nin signal strength between up- and downshifted plasma lines.",
"arxiv_id": "physics/0003019",
"authors": [
"Ingemar Haggstrom",
"Mikael Hedin",
"Takehiko Aso",
"Asta Pellinen-Wannberg",
"Assar Westman"
],
"categories": [
"physics.space-ph"
],
"journal_ref": "Adv. Polar Upper Atmos. Res., 14, 2000, pp 103--121",
"title": "Auroral field-aligned currents by incoherent scatter plasma line observations in the E region",
"url": "https://arxiv.org/abs/physics/0003019"
},
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