Study of Vertical Plasma Drifts and Spread-F Variability Using Ionospheric Radar Measurements over the Peruvian Sector

We use the Jicamarca Unattended Long term Investigations of the Ionosphere and Atmosphere (JULIA) radar system and the JULIA medium power mode to compare and analyze the characteristics of vertical ion drift and spread F occurrence over Peru during geomagnetically quiet periods. By combining multi year radar time series with event based analyses, we characterize the diurnal, seasonal, and solar activity dependencies of pre sunset and post sunset vertical drift behavior, and we quantify the magnitudes and timing of peak values as well as the associated spread F occurrence patterns for the period 2001–2025. Our analysis reveals consistent pre reversal enhancement signatures that precede spread F initiation. We also present distinct seasonal patterns in drift variability that explain observed differences in spread F occurrence between equinox and solstice periods. Monthly and bimonthly average occurrence rates of 3 m F region irregularities are characterized as functions of local time and altitude. Our results show similar equinoctial occurrence patterns but significant differences during the solstices. We also compare irregularity occurrence near solar minimum and maximum. Our results agree with previous climatological studies of ionospheric irregularity occurrence. These observations can be used to improve ionospheric specification and to develop empirical models of ionospheric irregularities, and they demonstrate the unique value of continuous radar monitoring for advancing forecasting capabilities of ionospheric disturbances that impact radio propagation and navigation systems.