Factors determining spectral width of HF echoes from high latitudes

• Published in: Annales geophysicae (1988) Vol. 25; no. 3; pp. 675 - 687
• Main Authors: PONOMARENKO, P. V, WATERS, C. L, MENK, F. W
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau European Geophysical Society 29.03.2007; European Geosciences Union; Copernicus Publications
• Subjects: Earth Sciences; Earth, ocean, space; Exact sciences and technology; External geophysics; Ocean, Atmosphere; Physics of the high neutral atmosphere; Physics of the ionosphere; Physics of the magnetosphere; Sciences of the Universe; High latitude; Field line; Ionosphere (Ionospheric irregularities; Particle precipitation); Spectral properties; Latitudinal gradient; Electron precipitation; Ionosphere magnetosphere coupling; turbulence; Lifetime; Magnetospheric physics (Magnetosphere- ionosphere interactions); Particle precipitation; Ionospheric plasma; Ionospheric irregularity; Radar echo
• ISSN: 0992-7689; 1432-0576; 1432-0576
• DOI: 10.5194/angeo-25-675-2007

Spectral width is one of the standard data types produced by the Super Dual Auroral Radar Network (SuperDARN). A pronounced latitudinal gradient in spectral width has been reported in the literature and is used as an empirical proxy for the ionospheric footprint of the open-closed field-line boundary. In this work we investigated the daytime radar echo properties near the spectral width boundary using a multi-frequency sounding regime. We have found that the relatively large spectral width values ≥150 m/s observed poleward of the boundary are produced by ionospheric irregularities with lifetime τl≃10–25 ms, which is essentially independent of the scale size. These irregularities are statistically co-located with low-energy (~100 eV) electron precipitation, which may play a major role in producing F-region turbulence above 75 MLAT via restructuring the ionospheric plasma on time scales ~τl.