HR: 1340h
AN: A43A-0072    [Abstracts]
TI: Zonal Drift Velocities of Ionospheric Plasma Bubbles over Indonesia:Comparison Between GPS and Optical Measurements
AU: * Ito, Y
EM: yosikuni@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Honohara 3-13, Toyokawa, 442-8507 Japan
AU: Otsuka, Y
EM: otsuka@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Honohara 3-13, Toyokawa, 442-8507 Japan
AU: Shiokawa, K
EM: shiokawa@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Honohara 3-13, Toyokawa, 442-8507 Japan
AU: Kotake, N
EM: kotake@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Honohara 3-13, Toyokawa, 442-8507 Japan
AU: Suzuki, S
EM: shin@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Honohara 3-13, Toyokawa, 442-8507 Japan
AU: Ogawa, T
EM: ogawa@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Honohara 3-13, Toyokawa, 442-8507 Japan
AB: We have operated three single-frequency GPS receivers and an all-sky airglow imager at the Equatorial Atmosphere Radar (EAR) site (0.20S, 100.32; geomagnetic latitude 10.6S) in West Sumatra, Indonesia since October 2002 and January 2003, respectively. Using these instruments, we investigated drift velocities of equatorial plasma bubbles. The GPS receivers sampled GPS signal intensity at 20 Hz. Mutual distance of the three GPS antennas are 100-150 m. Drift velocities of the ionospheric irregularities causing the scintillation were measured using cross-correlation analysis with time series of the GPS signal intensity obtained from the three receivers. The measurement showed that the drift velocity was 150 m/s eastward between 2100 and 2200 LT and decreased to 70 m/s at 2300 LT on the night of March 23, 2004. Simultaneously, 630-nm airglow depletions caused by plasma bubbles were observed in the all-sky airglow images. The all-sky images were converted to maps in geographical coordinates, assuming that the airglow layer exists at 250 km altitude. From time sequence of the image, the depletions were found to move eastward at 100 m/s at 2200 LT and 60 m/s at midnight. The zonal drift velocity obtained from the airglow measurements is 50 m/s smaller than that obtained from the GPS measurements at 2200 LT, while the velocities obtained from the GPS and airglow measurements are almost identical around midnight. The difference of the velocities at the post-sunset period is expected to be caused by the polarization electric fields within the plasma bubbles, because the ionospheric irregularities with scale sizes of 300 m, which cause the scintillation, moves by ExB drift. Our observational result suggests that southward/downward polarization electric fields exist within the plasma bubbles at the post-sunset period.
DE: 0343 Planetary atmospheres (5210, 5405, 5704)
DE: 2435 Ionospheric disturbances
DE: 2439 Ionospheric irregularities
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005