Neutral Wind Profiles During Periods of Eastward and Westward Equatorial Electrojet

The equatorial electrojet (EEJ) is a band of zonal electric current flowing along the magnetic equator in the dayside E-region ionosphere. The direction of the EEJ is often eastward but sometimes westward. The mechanism for generating westward EEJ is not fully understood. This study examines the relationship between the eastward/westward EEJ and equatorial neutral winds using simultaneous observations of the EEJ from the European Space Agency's Swarm satellite mission and thermospheric winds from the Michelson Interferometer for Global High-resolution Thermospheric Imaging on NASA's Ionospheric Connection Explorer mission during December 2019-January 2021. Significant differences are found in the average zonal wind profiles between times of eastward and westward EEJ. The EEJ intensity correlates negatively (R = -0.54) and positively (R = 0.58) with the eastward wind velocities at similar to 110 and similar to 140 km, respectively. The results suggest that the modulation of the zonal electric field by the equatorial zonal wind plays a role in producing the westward EEJ.