Open AccessAspect angle dependence of the E region irregularity velocity at large flow angles
Author(s) -
Makarevich R. A.,
Koustov A. V.,
Senior A.,
Uspensky M.,
Honary F.,
Dyson P. L.
Publication year - 2007
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007ja012342
Subject(s) - incoherent scatter , drift velocity , physics , radar , doppler effect , plasma , stochastic drift , flow velocity , computational physics , optics , flow (mathematics) , scattering , mechanics , telecommunications , statistics , mathematics , quantum mechanics , astronomy , computer science
We present the Doppler velocity observations of 1‐m plasma waves in the auroral E region by the Scandinavian Twin Auroral Radar Experiment (STARE) Norway VHF coherent radar in the context of simultaneous and coincident measurements of electron and ion drift velocities determined by the European Incoherent Scatter (EISCAT) tristatic radar facility. The measurements were performed in the afternoon sector (1500–2000 MLT) at seven locations along the STARE radar beam 2 with different values of the magnetic off‐perpendicular (aspect) angle α between 0.48° and 2.63° and at large angles with respect to the electron background drift (θ = 55°–90°). It is demonstrated that the STARE line‐of‐sight velocity, normalized to the EISCAT‐derived electron drift speed at large flow angles, exhibits a decrease with increasing aspect angle, and the rate of decrease is investigated as a function of the flow angle. We also compare the STARE velocity with the electron and ion drift velocity components along the STARE radar beam look direction and show that, at large aspect angles, the E region velocity is correlated (anticorrelated) with the ion (electron) drift velocity component. The results are discussed in the contexts of the linear fluid theory of the modified two‐stream plasma instability and the theory of anomalous collisions.