Measurements of the Plasma Vertical and Zonal Drift Velocities: Comparison of the Results From Digisondes and Incoherent Scatter Radar During the Copex Campaign

Simultaneous measurements taken by instruments located at the Brazilian and Peruvian longitudinal sectors are presented in this work. These studies show the vertical and zonal drift velocity time series obtained in two periods of observation in October and November, 2002, during the COPEX campaign. Three instruments provided the data: two Digisondes (DPS-4 type), one located at Cachimbo (9.5°S, 54.8°W, dip -4.25°), Brazil, and another one located at the Jicamarca Radio Observatory (11.95°S, 76.87°W, dip ~ 1°), and the Incoherent Scatter Radar also operates at Jicamarca. Earlier work has shown a comparative study of the vertical drift velocity obtained from these instruments (Bertoni et al., 2006). The values of the vertical velocity measurements at the two longitude sectors, Jicamarca (JIC) and Cachimbo (CAC), presented very reasonable correlation, around sunset/evening hours, during moderate magnetic activity. In this paper, we have processed the zonal component of the ionospheric plasma drift velocity. Our results show that the Digisonde drift velocity local time variation, for both the vertical and zonal components, follow the same behavioral trends as that of the velocities from the ISR, during most of the nighttime hours, including the afternoon and sunrise hours. It motivates us to use the zonal velocity of the ionospheric plasma (vertical dynamo electric fields) obtained by Digisondes, in order to further discuss the behavior of zonal and vertical plasma drift for periods conditioned by quiescent and disturbed magnetic and solar activity around the time ranges with good correlation.