Articles | Volume 24, issue 5
Ann. Geophys., 24, 1411–1418, 2006
https://doi.org/10.5194/angeo-24-1411-2006

Special issue: The 11th International Symposium on Equatorial Aeronomy (ISEA-11),...

Ann. Geophys., 24, 1411–1418, 2006
https://doi.org/10.5194/angeo-24-1411-2006

  03 Jul 2006

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 S. Fukao et al.
  • 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.