Equatorial zonal plasma drifts measured by the C/NOFS satellite during the 2008-2011 solar minimum

We use the measurements by the Vector Electric Field Investigation (VEFI) on board the Communication/Navigation Outage Forecasting System (C/NOFS) satellite to study the local time and seasonal- and longitudinal-dependent climatology of equatorial F region zonal plasma drifts during 2008-2011. These drifts are essentially westward during the day and eastward at night. Over Jicamarca Radio Observatory, the satellite measurements are in good agreement with incoherent scatter radar drifts. Our data show strong longitudinal variations, particularly in the South American sector during the solstices. The equinoctial data exhibit short-lived and largely enhanced westward drifts near sunrise and wave-4 structures from the early afternoon to late night equinoctial periods. The nighttime eastward drifts are largest near the western American sector at all seasons. The June solstice postmidnight eastward drifts decrease sharply at longitudes of about 310 degrees and have much smaller values in the entire Eastern Hemisphere. We also briefly discuss the relationship between the longitude-dependent vertical and zonal plasma drifts.