A statistical study of plasma bubble zonal drift velocity variations with geomagnetic activity and events of corotating and transient solar wind streams

A study of the plasma bubble zonal drift velocities is carried out using experimental airglow data registered at Cachoeira Paulista (22.5° S, 45° W, dip 30° S) during the period from October to March, between 1980-1994. This study is based upon 109 nights of zonal scanning photometer measurements of OI 630 nm airglow. The zonal velocity magnitudes of the ionospheric bubbles are investigated taking into account the geomagnetic effects. The geomagnetic activity condition in this study is based on the 3-hour geomagnetic index Kp. A detailed analysis of these plasma bubble velocities, as a function of geomagnetic activity, shows that the velocity variations expressed by Vfinal – Vinitial are smaller during quiet nights than during disturbed nights. In addition, it is noted that the mean velocities present the highest (lowest) values during quiet (disturbed) nights of solar maximum (minimum). Also it is observed that the tendency of the plasma bubbles is to appear earlier during corotating stream events than transient or no stream periods.