TY - JOUR
T1 - Spatial evolution of frictional heating and the predicted thermospheric wind effects in the vicinity of an auroral arc measured with the Sondrestrom incoherent-scatter radar and the Reimei satellite
AU - Oyama, S.
AU - Tsuda, T. T.
AU - Sakanoi, T.
AU - Obuchi, Y.
AU - Asamura, K.
AU - Hirahara, M.
AU - Yamazaki, A.
AU - Kasaba, Y.
AU - Fujii, R.
AU - Nozawa, S.
AU - Watkins, B. J.
PY - 2009
Y1 - 2009
N2 - Simultaneous observation with the Sondrestrom incoherent-scatter (IS) radar and the Reimei satellite was conducted on 3 October 2007. The objective was to measure horizontal patterns of the ionospheric structure in the vicinity of an auroral arc. The IS radar was scanned azimuthally with a fixed elevation angle, and the satellite narrow-view camera (557.7 nm) was directed downward taking pictures every 0.12 s. A stationary auroral arc was captured at 05:17 UT (02:54 MLT) with both instruments simultaneously. Gross ionospheric features measured with the IS radar around the arc were in good agreement with the expected magnetosphere-ionosphere current system. Of particular interest was the horizontal pattern in the ion speed and temperature in the F region. The ion speed within the arc was close to zero; by contrast the larger ion speed (350-400 m s-1) on the poleward side was parallel to the arc and almost no horizontal shear within about 20 km width perpendicular to the arc. This area was separated into two parts by the ion temperature: one was associated with clear enhancements in excess of 1200 K, and another was with more moderate enhancements (less than ∼1000 K). The widths of the two areas were approximately 10 km each. The horizontal shear seen in the ion temperature suggested the presence of a narrow thermospheric wind shear of about 10 km width. This paper suggests that the possible cause for the thermospheric wind shear was ion drag associated with localized soft particle precipitation or F-region ionization.
AB - Simultaneous observation with the Sondrestrom incoherent-scatter (IS) radar and the Reimei satellite was conducted on 3 October 2007. The objective was to measure horizontal patterns of the ionospheric structure in the vicinity of an auroral arc. The IS radar was scanned azimuthally with a fixed elevation angle, and the satellite narrow-view camera (557.7 nm) was directed downward taking pictures every 0.12 s. A stationary auroral arc was captured at 05:17 UT (02:54 MLT) with both instruments simultaneously. Gross ionospheric features measured with the IS radar around the arc were in good agreement with the expected magnetosphere-ionosphere current system. Of particular interest was the horizontal pattern in the ion speed and temperature in the F region. The ion speed within the arc was close to zero; by contrast the larger ion speed (350-400 m s-1) on the poleward side was parallel to the arc and almost no horizontal shear within about 20 km width perpendicular to the arc. This area was separated into two parts by the ion temperature: one was associated with clear enhancements in excess of 1200 K, and another was with more moderate enhancements (less than ∼1000 K). The widths of the two areas were approximately 10 km each. The horizontal shear seen in the ion temperature suggested the presence of a narrow thermospheric wind shear of about 10 km width. This paper suggests that the possible cause for the thermospheric wind shear was ion drag associated with localized soft particle precipitation or F-region ionization.
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U2 - 10.1029/2009JA014091
DO - 10.1029/2009JA014091
M3 - Article
AN - SCOPUS:72649100028
VL - 114
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
SN - 2169-9380
IS - 7
M1 - A07311
ER -