The equatorial electric field (EEF), created by the E-region dynamo, drives vertical plasma drifts which influence many important ionospheric processes. Vertical drifts drive the plasma fountain which results in the equatorial ionization anomaly (EIA), a dense band of plasma about 20 degrees north and south of the magnetic equator. Understanding the EEF is important for other processes as well, including the equatorial electrojet (EEJ) and ionospheric density irregularities.

The JULIA (Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere) radar located near Lima, Peru has been measuring these vertical plasma drifts at an altitude of 150 km since about 1996. Here we have created a climatological model of these drifts as a function of local time, season and solar flux level. The model contains two components: an estimate of the climatological mean as well as the standard deviation from the mean.

Fig. 1: Scherliess and Fejer model output (left), raw JULIA vertical drift data (middle) and JULIA Vertical Drift Model output using EUVAC index of 80 (right).