|
|
 |
|
|
Ann. Geophys., 23, 2391-2399, 2005
www.ann-geophys.net/23/2391/2005/
© European Geosciences Union 2005
The first coordinated observations of mid-latitude E-region quasi-periodic radar echoes and lower thermospheric 557.7-nm airglow
T. Ogawa1, Y. Otsuka1, F. Onoma1, K. Shiokawa1, and M. Yamamoto2
1Solar-Terrestrial Environment Laboratory, Nagoya University, Honohara, Toyokawa, Aichi 442-8507, Japan
2Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
Abstract. We present the first coordinated observations of quasi-periodic (QP) radar
echoes from sporadic-E (Es) field-aligned irregularities (FAIs),
OI 557.7-nm airglow, and neutral winds in a common volume over Shigaraki,
Japan (34.9° N, 136.1° E) on the night of 5 August 2002 during the SEEK-2
campaign. QP echo altitudes of 90-110 km were lower than usual by 10 km,
enabling us to make a detailed comparison among QP echoes, airglow intensity,
and neutral wind at around 96 km altitude. Eastward movement of the QP echo
regions is consistent with the motions of neutral winds, airglow structures,
and FAIs, suggesting that the electrodynamics of Es-layers is
fundamentally controlled by the neutral atmospheric dynamics. During the QP echo
event, the echo altitudes clearly went up (down) in harmony with an airglow
enhancement (subsidence) that also moved to the east. This fact suggests that
the eastward-moving enhanced airglow region included an upward (downward)
component of neutral winds to raise (lower) the altitude of the wind-shear node
responsible for the Es formation. The airglow intensity, echo intensity,
and Doppler velocity of FAIs at around 96 km altitude fluctuated with periods
from 10 min to 1h, indicating that these parameters were modulated with
short-period atmospheric disturbances. Some QP echo regions below 100km
altitude contained small-scale QP structures in which very strong neutral
winds exceeding 100 m/s existed. The results are compared with recent
observations, theories, and simulations of QP echoes.
Keywords. Ionosphere (Ionosphere-atmosphere interactions;
Ionospheric irregularities; Mid-latitude ionosphere)
Full Article in PDF (4079 KB) |
|
|
