Factors determining spectral width of HF echoes from high latitudes

P. V. Ponomarenko (1) , C. L. Waters (1) , F. W. Menk (1)

1 University of Newcastle

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 ?_l?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 ~?_l.

Domaines: Océan, Atmosphère; Sciences de la Terre

P. V. Ponomarenko, C. L. Waters, F. W. Menk. Factors determining spectral width of HF echoes from high latitudes. Annales Geophysicae, 2007, 25 (3), pp.675-687. ⟨hal-00318291⟩