Equatorial Nighttime Thermospheric Zonal Wind Jet Response to the Temporal Oscillation of Solar Wind

Abstract

AbstractThis work investigates the response of the equatorial thermospheric wind jet to the temporal oscillation of the Bz component of the interplanetary magnetic field using Thermosphere Ionosphere Electrodynamics General Circulation Model simulations and CHAllenging Minisatellite Payload observations. The thermospheric wind jet is formed in the magnetic equatorial region with the strongest zonal winds. Both the morning westward jet and the nighttime eastward wind jet at the dip equator decrease during the oscillation periods of IMF Bz. Ion drag dominates the deceleration of the equatorial eastward wind jet in the nighttime, with a minor contribution from the viscous force. The relative motion between the ions and neutrals has a dominant influence on the ion drag at the 60–180°W and 107–180°E geographic longitude; at other longitudes, both relative velocity (∆velocity) and electron density changes (∆Ne) are dominant. Moreover, the decrease in the equatorial eastward wind jet at 20 magnetic local time, which is also driven by ion drag, is significant above 270 km. The generation of the equatorial westward wind jet disturbance is significantly influenced by ∆velocity at all altitudes, whereas ∆Ne becomes important below 450 km.