Measurements of the dynamics and coupling of the equatorial thermosphere and the F-region ionosphere in Peru

Simultaneous Fabry-Perot Interferometer (FPI) and Incoherent Scatter Radar (ISR) observations from Arequipa and Jicamarca, Peru, respectively, were obtained on 24 and 25 September 1986, during which there was substantial geomagnetic activity. Comparison of the neutral thermosphere’s zonal velocity (measured by the FPI during twilight and night-time) and the F-region plasma’s zonal drift (measured by the ISR throughout the day and night) indicate that at certain times, such as evening twilight, the two motions are not correlated, but that in the late night they are. The change from uncorrelated to correlated motion occurs as the ionospheric electron density decays, leading to a decreasing Pedersen conductivity which diminishes E-region shorting of the F-region dynamo, allowing the local thermospheric winds to c&trol the F-region ionospheric drift.