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Ann. Geophys., 26, 2061-2067, 2008
www.ann-geophys.net/26/2061/2008/
© European Geosciences Union 2008
The role of the vertical E×B drift for the formation of the longitudinal plasma density structure in the low-latitude F region
S.-J. Oh1,*, H. Kil2, W.-T. Kim1, L. J. Paxton2, and Y. H. Kim3
1Department of Physics and Astronomy, FPRD, Seoul National University, Seoul, Korea
2Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, USA
3Department of Astronomy and Space Science, Chungnam National University, Daejeon, Korea
*now at: SELab, Seoul, Korea
Abstract. The formation of a longitudinally periodic plasma density structure in the
low-latitude F region by the effect of vertical E×B drift
was investigated by analyzing the ROCSAT-1 satellite data and conducting
SAMI2 model simulations. The daytime equatorial ionosphere observed during
the equinox in 1999–2002 from ROCSAT-1 showed the formation of wave number-4
structures in the plasma density and vertical plasma drift. The coincidence
of the longitudes of the peak density with the longitudes of the peak upward
drift velocity during the daytime supported the association of the
longitudinal density structure with the vertical E×B drift.
The reproduction capability of the observed wave-4 structure by the effect of
vertical E×B drift was tested by conducting SAMI2 model
simulations during the equinox under solar maximum condition. When the
ROCSAT-1 vertical drift data were used, the SAMI2 model could reproduce the
observed wave-4 density structure in the low-latitude F region. On the other
hand, the SAMI2 model could not reproduce the observed wave-4 structure using
the Scherliess and Fejer vertical E×B drift model. The
observation and model simulation results demonstrated that the formation of
the longitudinally periodic plasma density structure can be explained by the
longitudinal variation of the daytime vertical E×B drift.
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