Estudos da deriva zonal e dinâmica das bolhas de plasma na região tropical / Zonal drifts and dynamical study of the plasma bubbles over the tropical region

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

All-sky airglow OI 630 nm images obtained at Cachoeira Paulista in the period from January 1989 to December 1991 and January 1995 to December 1997 are analysed to study the nocturnal and seasonal dynamic behavior, as well as bifurcation variations of plasma bubbles during high and low solar activity. Also, all-sky images from São João do Cariri and Cachoeira Paulista are analysed from October 1998 to May 2000 in order to investigate the nocturnal, seasonal and latitudinal behavior of the ionospheric plasma zonal drift velocities in the tropical region. The statistics shows that the occurrence frequency of plasma bubbles is very low during the period May-August and maximizes during October-March for both low and high solar activity periods. However, the occurrence frequency is larger during high solar activity. It is noticed that the occurrence of bifurcation in bubbles is also larger during high solar activity. It is observed that, when the ratio of the electron densities outside and inside the depletion is less than 4, the bifurcation tendency is high, when it is greater than 4, the bifurcation tendency is small. The ionospheric plasma zonal drift velocities in the tropical region, for the period analysed, show a high eastward velocity during 20:00-22:00 local time and, after midnight, the velocities decrease. Another characteristic observed is a significant latitudinal variation in the ionospheric plasma zonal drift velocities in the tropical region between 20:00-22:00 local time, which may be related to the ionospheric equatorial anomaly and the zonal neutral wind. Also, it is noticed that, during intense geomagnetic storms, the plasma bubbles move westward. This behavior may be due to the effects of magnetospheric electric fields penetrating to tropical latitudes, during enhanced magnetic activity.

ASSUNTO(S)

luminescence deriva ionosférica upper atmosphere luminescência bolhas de plasma ionospheric drift geofÍsica espacial f region região f alta atmosfera plasma bubbles

ACESSO AO ARTIGO

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