Imaging observations of nighttime mid-latitude F-region field-aligned irregularities by an MU radar ultra-multi-channel system S. Saito1,*, M. Yamamoto2, and H. Hashiguchi2 1National Institute of Information and Communications Technology, Nukui-kita 4-2-1, Koganei, Tokyo 184-8795, Japan 2Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan *now at: Electronic Navigation Research Institute, Jindaiji-higashi 7-42-23, Chofu, Tokyo 182-0012, Japan
Abstract. Mid-latitude F-region field-aligned irregularities (FAIs) were studied
by using the middle-and-upper atmosphere (MU) radar ultra-multi-channel system
with the radar imaging technique.
On 12 June 2006, F-region FAI echoes with a period
of about one hour were observed intermittently.
These echoes were found to be embedded in medium-scale
traveling ionospheric disturbances (MSTIDs) observed as variations of total electron
The echoes drifting away from (toward) the radar were observed in
the depletion (enhancement) phase of the MSTID.
The Doppler velocity of the echoes is consistent with the range rates in the
the range-time-intensity (RTI) maps.
Fine scale structures with a spatial scale of 10 km or less were
found by the radar imaging analysis.
Those structures with positive Doppler velocities (moving away from the radar)
appeared to drift
north- (up-) westward, and those with negative Doppler velocities
south- (down-) eastward approximately along the wavefronts of the MSTID.
FAIs with positive Doppler velocities filling TEC depletion regions were observed.
Citation: Saito, S., Yamamoto, M., and Hashiguchi, H.: Imaging observations of nighttime mid-latitude F-region field-aligned irregularities by an MU radar ultra-multi-channel system, Ann. Geophys., 26, 2345-2352, doi:10.5194/angeo-26-2345-2008, 2008.