Browsing by Author "Tracy, Brian D."
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Item Restricted Equatorial zonal plasma drifts measured by the C/NOFS satellite during the 2008–2011 solar minimum(American Geophysical Union, 2013-06-26) Fejer, Bela G.; Tracy, Brian D.; Pfaff, Robert F.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° 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.Item Restricted Lunar tidal effects in the electrodynamics of the low latitude ionosphere(Elsevier, 2013-02-04) Fejer, Bela G.; Tracy, Brian D.The low latitude ionosphere is highly variable over a large range of temporal and spatial scales even during geomagnetically quiet periods, largely as a result of electrodynamic plasma drift effects. Several recent experimental and modeling studies have investigated the electrodynamic response of the low latitude ionosphere to high latitude and lower atmospheric wave activity, particularly during sudden stratospheric warmings. In this work, we review some recent results on the short-term variability of equatorial vertical plasma drifts measured mostly at the Jicamarca Radio Observatory and their effects on equatorial short-scale spread F irregularities. We show that lunar tidal semidiurnal and diurnal effects, which have been largely ignored in most studies, can play significant roles in low latitude ionospheric variability.