Journal cover Journal topic
Annales Geophysicae Sun, Earth, planets, and planetary systems An interactive open-access journal of the European Geosciences Union
Ann. Geophys., 24, 1411-1418, 2006
© Author(s) 2006. This work is distributed under
the Creative Commons Attribution 3.0 License.
03 Jul 2006
Eastward traverse of equatorial plasma plumes observed with the Equatorial Atmosphere Radar in Indonesia
S. Fukao1, T. Yokoyama1,*, T. Tayama1,**, M. Yamamoto1, T. Maruyama2, and S. Saito2 1Research Institute for Sustainable Humanosphere, Kyoto University, Kyoto, Japan
2National Institute of Information and Communications Technology, Tokyo, Japan
*now at: Solar-Terrestrial Environment Laboratory, Nagoya University, Aichi, Japan
**now at: NTT Data Co. Ltd., Tokyo, Japan
Abstract. The zonal structure of radar backscatter plumes associated with Equatorial Spread F (ESF), probably modulated by atmospheric gravity waves, has been investigated with the Equatorial Atmosphere Radar (EAR) in West Sumatra, Indonesia (0.20° S, 100.32° E; dip latitude 10.1° S) and the FM-CW ionospheric sounders on the same magnetic meridian as the EAR. The occurrence locations and zonal distances of the ESF plumes were determined with multi-beam observations with the EAR. The ESF plumes drifted eastward while keeping distances of several hundred to a thousand kilometers. Comparing the occurrence of the plumes and the F-layer uplift measured by the FM-CW sounders, plumes were initiated within the scanned area around sunset only, when the F-layer altitude rapidly increased. Therefore, the PreReversal Enhancement (PRE) is considered as having a zonal variation with the scales mentioned above, and this variation causes day-to-day variability, which has been studied for a long time. Modulation of the underlying E-region conductivity by gravity waves, which causes inhomogeneous sporadic-E layers, for example, is a likely mechanism to determine the scale of the PRE.

Citation: Fukao, S., Yokoyama, T., Tayama, T., Yamamoto, M., Maruyama, T., and Saito, S.: Eastward traverse of equatorial plasma plumes observed with the Equatorial Atmosphere Radar in Indonesia, Ann. Geophys., 24, 1411-1418,, 2006.
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