|
|
 |
|
|
Ann. Geophys., 22, 3123-3128, 2004
www.ann-geophys.net/22/3123/2004/
© European Geosciences Union 2004
Plasma bubble zonal velocity variations with solar activity in the Brazilian region
P. M. Terra, J. H. A. Sobral, M. A. Abdu, J. R. Souza, and H. Takahashi
Instituto Nacional de Pesquisas Espaciais – INPE, Avenida dos Astronautas, 1758, Jardim da Granja, CX. 515, CEP: 12.245-970, São José dos Campos, São Paulo, Brazil
Abstract. A statistical study of the zonal drift velocities of the ionospheric plasma
bubbles using experimental airglow data acquired at the low-latitude station
Cachoeira Paulista (Geogr. 22.5° S, 45° W, dip angle 28° S) during the period of
October to March, between 1980 and 1994, is presented here. This study is
based on 109 nights of zonal plasma bubble velocity estimations as
determined from bubbles signatures on the OI 630nm scanning photometer
airglow data. The zonal velocity magnitudes of the plasma bubbles are
investigated with respect to solar activity and local time. It is verified
that these velocities tend to increase with the solar EUV flux, using the
solar 10.7-cm radio flux as a proxy (F10.7). These velocities are seen to be
larger during the solar maximum activity period than in the solar minimum
period. As to the local time variation, they are seen to peak before
midnight, in the 20:30-22:30 LT time frame, depending on the season. The
all-data plot based on the 109 nights of airglow experiments shows that the
plasma bubble mean zonal drift velocities tend to decrease with local time,
but they peak at 22:25 LT, where the velocity magnitude reaches 127.4ms-1.
The zonal drift variations with local time and solar flux are
shown in Figs. 1 and 2, respectively.
Full Article in PDF (618 KB) |
|
|
