The mesosphere and lower thermosphere (MLT) region is dominated globally by dynamics at various scales: planetary waves, tides, gravity waves, and stratified turbulence. The latter two can coexist and be significant at horizontal scales less than 500 km, scales that are difficult to measure. This study presents a recently deployed multistatic specular meteor radar system, SIMONe Peru, which can be used to observe these scales. The radars are positioned at and around the Jicamarca Radio Observatory, which is located at the magnetic equator. Besides presenting preliminary results of typically reported large‐scale features, like the dominant diurnal tide at low latitudes, we show results on selected days of spatially and temporally resolved winds obtained with two methods based on: (a) estimation of mean wind and their gradients (gradient method), and (b) an inverse theory with Tikhonov regularization (regularized wind field inversion method). The gradient method allows improved MLT vertical velocities and, for the first time, low‐latitude wind field parameters such as horizontal divergence and relative vorticity. The regularized wind field inversion method allows the estimation of spatial structure within the observed area and has the potential to outperform the gradient method, in particular when more detections are available or when fine adaptive tuning of the regularization factor is done. SIMONe Peru adds important information at low latitudes to currently scarce MLT continuous observing capabilities. Results contribute to studies of the MLT dynamics at different scales inherently connected to lower atmospheric forcing and E‐region dynamo related ionospheric variability.

We conducted a comprehensive analysis of the vertical drifts and equatorial spread F (ESF) measurements made by the Jicamarca incoherent scatter radar (ISR) between 1994 and 2013. The ISR measurements allowed us to construct not only updated climatological curves of quiet‐time vertical plasma drifts but also time‐versus‐height maps of ESF occurrence over the past two solar cycles. These curves and maps allowed us to better relate the observed ESF occurrence patterns to features in the vertical drift curves than previously possible. We identified an excessively high occurrence of post‐midnight F region irregularities during December solstice and low solar flux conditions. More importantly, we also found a high occurrence of ESF events during sudden stratospheric warming (SSW) events. We also proposed and evaluated metrics of evening enhancement of the vertical drifts and ESF occurrence, which allowed us to quantify the relationship between evening drifts and ESF development. Based on a day‐to‐day analysis of these metrics, we offer estimates of the minimum pre‐reversal enhancement (PRE) peak (and mean PRE) values observed prior to ESF development for different solar flux and seasonal conditions. We also found that ESF irregularities can reach the altitudes at least as high as 800 km at the magnetic equator even during low solar flux conditions.

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.

Previous studies of the Earth's low‐latitude ionosphere using in situ measurements made by sensors on the Communication/Navigation Outage Forecasting System (C/NOFS) satellite showed an unexpected predominance of equatorial spread F (ESF) events in the postmidnight sector during June and December solstice months of the 2008–2009 deep solar minimum. It has been suggested that these events might have been driven by the unusual behavior of the equatorial plasma drifts, which showed an abnormal upward peak around midnight during the same period. We use coherent backscatter radar (Jicamarca Unattended Long‐term Investigations of the Ionosphere and Atmosphere ‐ JULIA) measurements made at the Jicamarca Radio Observatory (11.95°S, 76.87°W, ∼1^∘ dip lat) in Peru to better understand the origin of the ESF irregularities observed by C/NOFS. The radar observations show that ESF events during December solstice start in the postsunset sector. These ESF events and the conditions for their development are shown to continue through midnight hours. The predominance of postmidnight irregularities on C/NOFS observations during December solstice is caused by the slow vertical development of the ESF structures, which only reach the topside near midnight in most cases. On June solstice, however, JULIA observations show that ESF started predominately in the midnight to postmidnight sector. Collocated digisonde observations provide additional insight on F‐region conditions leading to these ESF events.