Comparison of zonal neutral winds with equatorial plasma bubble and plasma drift velocities

Abstract

A one-year dataset spanning March 2011-March 2012 of coincident observations of night time thermospheric zonal neutral winds, equatorial plasma bubble (EPB) velocities, and zonal plasma drifts are used to examine the relationship between the thermosphere and ionosphere near the geomagnetic equator over Peru. Thermospheric neutral winds are determined by using a bistatic Fabry–Perot interferometer (FPI) experiment located at Merihill and Nazca in Peru. The ambient plasma drift velocities were obtained using the incoherent scatter radar at the Jicamarca Radio Observatory in Peru. The EPB zonal velocities were estimated utilizing images of the OI 630.0-nm emission recorded by a narrow-field optical imaging system at the Cerro Tololo InterAmerican Observatory in Chile. The joint analysis of these datasets illustrates that the night time and night-to-night variations in the zonal neutral winds, EPB velocities, and plasma drifts are well correlated. This consistent result of the local time variations of the neutral winds with that of EPB and plasma drifts illustrates that the F-region dynamo is, in general, fully activated. However, at times, the magnitude of the EPB velocities and the plasma drifts are different from the neutral winds. It is plausible that such a difference is due either to the effect of polarization electric fields developed inside the EPB or due to the latitudinal gradient of the neutral winds and EPB velocity measurements since the EPB velocities are estimated at a higher latitude, corresponding to an apex altitude of ~400 km, than the wind estimates, which derive from an apex altitude of ~250 km.