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630.0 nm all-sky imaging data are used to detect airglow depletions associated with equatorial spread F. Pairs of imagers located at geomagnetically conjugate locations in the American sector at low and mid-latitudes provide information on the occurrence rate and zonal motion of airglow depletions. Airglow depletions are seen extending to magnetic latitudes as high as 25°. An asymmetric extension is observed with structures in the northern hemisphere reaching higher latitudes. By tracking the zonal motion of airglow depletions, zonal plasma drifts in the thermosphere can be inferred and their simultaneous behavior in both hemispheres investigated. Case studies using El Leoncito and Mercedes imagers in the southern hemisphere, and the respective magnetically conjugate imagers at Villa de Leyva and Arecibo, provide consistent evidence of the influence of the South Atlantic Magnetic Anomaly on the dynamics and characteristics of the thermosphere–ionosphere system at low and mid-latitudes. 

Abstract. In March 2014 an all-sky imager (ASI) was installed at the Jicamarca Radio Observatory (11.95°S, 76.87°W; 0.3°S MLAT). We present results of equatorial spread F (ESF) characteristics observed at Jicamarca and at low latitudes. Optical 6300 and 7774Å airglow observations from the Jicamarca ASI are compared with other collocated instruments and with ASIs at El Leoncito, Argentina (31.8°S, 69.3°W; 19.8°S MLAT), and Villa de Leyva, Colombia (5.6°N, 73.52°W; 16.4°N MLAT). We use Jicamarca radar data, in incoherent and coherent modes, to obtain plasma parameters and detect echoes from irregularities. We find that ESF depletions tend to appear in groups with a group-to-group separation around 400–500km and within-group separation around 50–100km. We combine data from the three ASIs to investigate the conditions at Jicamarca that could lead to the development of high-altitude, or topside, plumes. We compare zonal winds, obtained from a Fabry–Pérot interferometer, with plasma drifts inferred from the zonal motion of plasma depletions. In addition to the ESF studies we also investigate the midnight temperature maximum and its effects at higher latitudes, visible as a brightness wave at El Leoncito. The ASI at Jicamarca along with collocated and low-latitude instruments provide a clear two-dimensional view of spatial and temporal evolution of ionospheric phenomena at equatorial and low latitudes that helps to explain the dynamics and evolution of equatorial ionospheric/thermospheric processes. 

Abstract The lunar surface is constantly bombarded by the solar wind, photons, and meteoroids, which can liberate Na atoms from the regolith. These atoms are subsequently accelerated by solar photon pressure to form a long comet‐like tail opposite the sun. Near new moon, these atoms encounter the Earth's gravity and are “focused” into a beam of enhanced density. This beam appears as the ∼3° diameter Sodium Moon Spot (SMS). Data from the all sky imager at the El Leoncito Observatory have been analyzed for changes in the SMS shape and brightness. New geometry‐based relationships have been found that affect the SMS brightness. The SMS is brighter when the Moon is north of the ecliptic at new moon; the SMS is brighter when new moon occurs near perigee; and the SMS peaks in brightness ∼5 h after new moon. After removing these effects, the data were analyzed for long term and seasonal patterns that could be attributed to changes in source mechanisms. No correlation was found between the SMS brightness and the 11‐year solar‐cycle, the proton or the He⁺⁺flow pressure, the density, the speed or the plasma temperature of the solar wind, but an annual pattern was found. A ∼0.83 correlation (Pearson's “r”) was found between the SMS brightness and a 4‐year average of sporadic meteor rates at Earth, suggesting a cause‐and‐effect. The new insights gained from this long‐term study put new constraints on the variability of the potential sources of the Na atoms escaping from the Moon. 

Abstract All‐sky imagers located in Asiago, Italy (45.87^oN, 11.53^oE; 40.7^omagnetic latitude) and Sutherland, South Africa (32.37^oS, 20.81^oE; −40.7^omagnetic latitude) are used to study magnetically conjugate medium scale traveling ionospheric disturbances (MSTIDs). We present initial results from the first year of joint Asiago‐Sutherland data sets from July 2016 to June 2017. The 630.0‐nm airglow perturbations showing different kinds of waves were frequently observed. Some of these wave events resemble MSTIDs propagating south‐westward in Asiago, typical direction observed at other longitude sectors in the northern hemisphere. They are mostly observed as single bands propagating through the field of view of the all‐sky imagers. We select and analyze five cases of magnetically conjugate bands associated with MSTIDs. The bands observed at Sutherland move mainly westward, noticeably different from the north‐west direction of propagation of MSTIDs observed in the southern hemisphere. We compare the MSTIDs propagation speeds and find that three cases show larger values at Sutherland. When we compare the zonal speeds all the cases show larger values at Sutherland. On average, the propagation speed at Sutherland is 20% larger and the zonal speed is ~35% larger. The westward motion at Sutherland is explained by taking onto account how its magnetic declination (~24^oW) affects the orientation of the bands. The larger speed at Sutherland is due to the weaker Earth's magnetic field in the southern hemisphere and the particular configuration of the magnetic field lines in this longitude sector.