Observations of the nighttime thermospheric wind from two ground‐based Fabry‐Perot Interferometers are compared to the level 2.1 and 2.2 data products from the Michelson Interferometer Global High‐resolution Thermospheric Imaging (MIGHTI) onboard National Aeronautics and Space Administration's Ionospheric Connection Explorer to assess and validate the methodology used to generate measurements of neutral thermospheric winds observed by MIGHTI. We find generally good agreement between observations approximately coincident in space and time with mean differences less than 11 m/s in magnitude and standard deviations of about 20–35 m/s. These results indicate that the independent calculations of the zero‐wind reference used by the different instruments do not contain strong systematic or physical biases, even though the observations were acquired during solar minimum conditions when the measured airglow intensity is weak. We argue that the slight differences in the estimated wind quantities between the two instrument types can be attributed to gradients in the airglow and thermospheric wind fields and the differing viewing geometries used by the instruments.

We used reanalyzed Jicamarca radar measurements to study the response of equatorial ionospheric electrodynamics and spread F during the main phase of the large September 2017 geomagnetic storm. Our observations near dusk on 7 September show very large upward drifts followed by a large short‐lived downward drift perturbation that completely suppressed the lower F region plasma irregularities and severely decreased the backscattered power from the higher altitude spread F. We suggest that this large short‐lived westward electric field perturbation is most likely of magnetospheric origin and is due to a sudden and very strong magnetic field reconfiguration. Later in the early night period, data indicate large, mostly upward, drift perturbations generally consistent with standard undershielding and overshielding electric field effects, but with amplitudes significantly larger than expected. Our analysis suggests that occurrence of storm‐time substorms is one of the major factors causing the large nighttime westward and eastward electric field perturbations observed at Jicamarca near the storm main phase. Our analysis also suggests that magnetospheric substorms play far more important roles on the electrodynamics of the equatorial nighttime ionosphere than has generally been thought.

We used observations from the Peruvian Fabry‐Perot Interferometer network and from the Jicamarca radar to study the coupling of equatorial nighttime thermospheric winds and ionospheric drifts under moderate solar flux conditions. We show that the coupling of the extended quiet time zonal winds and drifts increases from dusk to midnight and is stronger during equinox than during June solstice. After midnight, they are strongly coupled, except during December solstice when the drifts are stronger. The nighttime disturbance zonal winds and drifts, derived by removing the corresponding quiet time values, are westward with peak magnitudes around midnight. They are in close agreement, except at early night when the winds are stronger, and have strongest (weakest) magnitudes during equinox (June solstice). We also present observations showing the strong neutral wind‐plasma drift coupling during the September 2017 and August 2015 large geomagnetic storms. We show that during the early phase of the September 2017 storm there were large and short‐lived, prompt penetration electric field‐driven, correlated oscillations (~1 hr) in the vertical and zonal plasma drifts, and in the zonal and meridional winds. These are the first observations of prompt penetration‐driven equatorial zonal and meridional wind disturbances. In this event, the vertical and zonal drift oscillations were anticorrelated, and the zonal winds followed the zonal drift oscillations with a delay of ~15 min. Our results illustrate the strong coupling of equatorial thermospheric winds and plasma drifts during geomagnetically quiet as well as during short‐lived prompt penetration and long‐lasting disturbance dynamo events.

We use extensive incoherent scatter radar observations from the Jicamarca Radio Observatory to study the local time and bimonthly dependence of the equatorial disturbance dynamo vertical plasma drifts on solar flux and geomagnetic activity. We show that the daytime disturbance drifts have generally small magnitudes with largest values before noon and an apparent annual variation. Near dusk, they are downward throughout the year with largest values during the equinoxes and smallest during June solstice. These downward drifts increase strongly with solar flux and shift to later local times. They also increase with increasing geomagnetically active conditions with no apparent local time shift. The equinoctial evening downward disturbance drifts are larger during the autumnal equinox than during the vernal equinox. The nighttime disturbance drifts are upward and have small seasonal and solar cycle dependence but increase strongly with geomagnetic activity, particularly in the late night sector. Our results are in general agreement with those from previous theoretical and experimental studies, except near dusk where our results show much stronger seasonal and solar cycle dependence.

We used Fabry‐Perot Interferometer (FPI) observations at Jicamarca, Nasca, and Arequipa, Peru, from 2011 to 2017 to study the nighttime zonal and meridional disturbance winds over the Peruvian equatorial region. We derived initially the seasonal‐dependent average thermospheric winds corresponding to 12 hr of continuous geomagnetically quiet conditions. These quiet‐time climatological winds, which are in general agreement with results from the Horizontal Wind Model (HWM14), were then used as baselines for the calculation of the disturbance winds. Our results indicate that the nighttime zonal disturbance winds are westward with peak values near midnight and with magnitudes much larger than predicted by the Disturbance Wind Model (DWM07). The premidnight equinoctial and June solstice westward disturbance winds have comparable values and increase with local time. The postmidnight westward disturbance winds decrease toward dawn and are largest during equinox and smallest during June solstice. The meridional average disturbance winds have small values throughout the night. They are northward in the premidnight sector, and southward with larger (smaller) values during December solstice (equinox) in the postmidnight sector. We also present observations showing that during the main and recovery phases of the April 2012 and May 2016 geomagnetic storms the zonal disturbance winds have much larger magnitudes and lifetimes (up to about 48 hr) than suggested by the HWM14. These observations highlight the importance of longer‐term disturbance wind effects. The large and short‐lived (about 2 hr) observed meridional wind disturbances are not reproduced by current climatological empirical models.