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This letter reports first simultaneous detection of F‐region plasma‐depleted structure in O(1D) 630.0 and O(1S) 557.7 nm airglow images on a geomagnetically quiet‐night (Ap = 3) of 26 June 2021 from mid‐latitude station (Hanle, India) due to enhanced thermospheric 557.7 nm emission. Since nighttime thermospheric 557.7 nm emission over mid‐latitudes is predominantly masked by significantly larger mesospheric component, F‐region plasma structures are rarely observed in 557.7 nm images. Interestingly, thermospheric 557.7 nm emission was not significant on the following geomagnetically quiet‐night as bands of medium‐scale traveling ionospheric disturbance were only observed in 630.0 nm images. Poleward wind generated by Equatorial Temperature and Wind Anomaly transported plasma from the boundary of equatorial ionization anomaly, causing significant electron density enhancement around 250 km and descent of F‐layer peak over Hanle on 26 June 2021. This amplified the dissociative recombination enabling the simultaneous detection of plasma‐depleted structure in 557.7 and 630.0 nm images. Plain Language Summary The thermospheric O(1S) 557.7 generated through dissociative recombination of O2+ in the F‐region is significantly lower than its mesospheric counterpart which is generated via the Barth mechanism in the Mesosphere‐Lower‐Thermosphere region. This causes difficulties in the simultaneous detection of mid‐latitude F‐region plasma structures in 630.0 and 557.7 nm airglow images during geomagnetically quiet nights of low solar active years. We report, for the first time, such simultaneous detection of plasma‐depleted structure from mid‐latitude station (Hanle, India) on a geomagnetically quiet night of 26 June 2021. Interestingly, the thermospheric 557.7 nm emission was not significant on the following geomagnetically quiet night as bands of medium‐scale traveling ionospheric disturbance were detected only in the 630.0 nm images. Results from multi‐instrument data sets showed the descent of F‐layer peak and significant electron density enhancement over Hanle. The local poleward wind generated by stronger Equatorial Temperature and Wind Anomaly on 26 June 2021 transported the plasma from the boundary of the equatorial ionization anomaly region to Hanle through geomagnetic field lines. This caused the enhancement of electron density around 250 km and descent of F‐layer peak over Hanle that created suitable condition for the amplification of dissociative recombination reaction. Key Points Simultaneous observation of mid‐latitude F‐region plasma‐depleted structure in O(1D) 630.0 and O(1S) 557.7 nm airglow images Significantly higher electron density is observed over the region on 26 June 2021 than on the following night at airglow emission altitude Thermospheric O(1S) 557.7 nm emission contributed significantly due to the enhancement in the dissociative recombination reaction

Most environmental satellite radiometers use solar reflectance information when it is available during the day but must resort at night to emission signals from infrared bands, which offer poor sensitivity to low-level clouds and surface features. A few sensors can take advantage of moonlight, but the inconsistent availability of the lunar source limits measurement utility. Here we show that the Day/Night Band (DNB) low-light visible sensor on the recently launched Suomi National Polar-orbiting Partnership (NPP) satellite has the unique ability to image cloud and surface features by way of reflected airglow, starlight, and zodiacal light illumination. Examples collected during new moon reveal not only meteorological and surface features, but also the direct emission of airglow structures in the mesosphere, including expansive regions of diffuse glow and wave patterns forced by tropospheric convection. The ability to leverage diffuse illumination sources for nocturnal environmental sensing applications extends the advantages of visible-light information to moonless nights.

The equatorial plasma bubble (EPB) evolutionary behavior in the Chinese sector remains poorly understood due to insufficient long‐term statistical characterization. Leveraging prior machine learning frameworks, this work presents the first statistical profile of EPB evolution over an entire solar cycle (2012–2022) in southern China, using airglow observations from Qujing, China (geographical: 25°N, 104°E; geomagnetic: 15.1°N, 176.7°E). The results reveal that: the relative occurrence frequency (ROF) peaks at ∼22:15 local time (LT) and exhibits equinoctial asymmetry, with spring and autumn showing double pre‐midnight peaks (22:15 and 23:30 LT), while winter displays a single peak (22:15 LT). The peak activities of the area within the observation field of view (FOV) and poleward magnetic latitude extension (PMLE) exhibit synchronous timing, predominantly occurring at 21:00, 23:00, 01:00, 03:30, and 05:00 LT. Before 02:00 LT, area in FOV and PMLE show seasonal variations: spring > autumn > winter. The zonal drift velocity (ZDV) peaks at 22:15 LT (primary), 01:45 LT (secondary), 03:45 LT (tertiary), and 05:45 LT (quaternary). Higher area in FOV, PMLE, and ZDV occur during high solar activity. Geomagnetic disturbances weakly increase ROF but suppress ZDV, PMLE, and area in FOV. Notably, our results show that the ROF near 00:00 LT drops sharply first and then rises suddenly, which persists regardless of statistical methodology. The correlations among PMLE, area in FOV, and speed exhibit seasonal variations, and are influenced by the intensity of solar and geomagnetic activity. These findings provide critical insights into EPB evolution in Chinese sector.

Using the observations of the 630-nm all-sky imagers (ASIs) located in the geomagnetic conjugate points in the American sector from 2014 to 2017, this study statistically analyzed the features of conjugate equatorial plasma bubbles (EPBs), including their occurrence rate, zonal width, location and zonal drift velocity. The results show that the occurrence rate of the EPBs that occur simultaneously at geomagnetic conjugate points is ∼84%. The zonal widths of the EPBs are mainly ∼100 km, and the width differences of EPBs between the northern and southern hemispheres are mainly within ±30 km. The zonal displacements of the center locations of the northern and southern EPBs are within ±50 km. The zonal drift velocities of the northern and southern EPBs are nearly equal. However, it should be noted that the velocity of the EPBs in the northern hemisphere is 10% faster than that in the southern hemisphere. The results suggest that conjugate EPBs are common. Moreover, the non-conjugate EPBs in the northern and southern hemisphere can occur occasionally, which is probably associated with the different ionospheric backgrounds between the two hemispheres. The features of the conjugate EPBs as shown in this study provides support for the nowcasting of EPBs in the conjugate hemispheres.

Measurements of hydroxyl (OH*) airglow intensity are a straightforward and cost-efficient method which allows the derivation of information about the climate and dynamics of the upper mesosphere/lower thermosphere (UMLT) on different spatiotemporal scales during darkness. Today, instrument components can be bought “off-the-shelf” and developments in detector technology allows operation without cooling, or at least without liquid nitrogen cooling, which is difficult to automate. This makes instruments compact and suitable for automated operation. Here, we briefly summarize why an OH* airglow layer exists, how atmospheric dynamics influence it and how temperature can be derived from OH* airglow measurements. Then, we provide an overview of the scientific results regarding atmospheric dynamics (mainly gravity waves (GWs) but also planetary waves (PWs) and infrasound) achieved with OH* airglow measurements. We focus on long-term ground-based OH* airglow measurements or airglow measurements using a network of ground-based instruments. The paper includes further results from global or near-global satellite-based OH* airglow measurements, which are of special importance for characterizing the OH* airglow layer. Additionally, the results from the very few available airborne case studies using OH* airglow instruments are summarized. Scientific and technical challenges for the next few years are described.

China’s Mars exploration mission has stimulated tremendous interest in planetary science exploration recently. To propose potential scientific research projects, this study presents a concept simulation for the measurement of Martian atmospheric winds using the Doppler Michelson interferometry technique. The simulation is based on the satellite instrument initially designed for the Dynamic Atmosphere Mars Observer (DYNAMO) project to measure vertical profiles of winds from the 1.27 μm airglow observations in the Martian atmosphere. A comprehensive DYNAMO measurement simulation forward model based on an orbit submodel, an atmospheric background field submodel, and an instrument submodel is developed using the Michelson equation. The simulated interferogram signal over the field of view (FOV) calculated by the forward model is associated with the filter transmittance function, column emission rate of airglow, wind velocity, temperature, and the Michelson phase. The agreement between the derived atmospheric signals from the simulated interferogram without altitude inversion and the input parameters used to initiate the forward model confirms the validity of the forward model.

The atmosphere of Mars is thin, although rich in dust aerosols, and covers a dry surface. As such, Mars provides an opportunity to expand our knowledge of atmospheres beyond that attainable from the atmosphere of the Earth. The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) lander is measuring Mars’s atmosphere with unprecedented continuity, accuracy and sampling frequency. Here we show that InSight unveils new atmospheric phenomena at Mars, especially in the higher-frequency range, and extends our understanding of Mars’s meteorology at all scales. InSight is uniquely sensitive to large-scale and regional weather and obtained detailed in situ coverage of a regional dust storm on Mars. Images have enabled high-altitude wind speeds to be measured and revealed airglow—faint emissions produced by photochemical reactions—in the middle atmosphere. InSight observations show a paradox of aeolian science on Mars: despite having the largest recorded Martian vortex activity and dust-devil tracks close to the lander, no visible dust devils have been seen. Meteorological measurements have produced a catalogue of atmospheric gravity waves, which included bores (soliton-like waves). From these measurements, we have discovered Martian infrasound and unexpected similarities between atmospheric turbulence on Earth and Mars. We suggest that the observations of Mars’s atmosphere by InSight will be key for prediction capabilities and future exploration.The InSight lander has expanded our knowledge of the atmosphere of Mars by observing various phenomena, including airglow, bores, infrasound and Earth-like turbulence.

The plasmas (electrons and ions) in the inner magnetosphere have wide energy ranges from electron volts to mega-electron volts (MeV). These plasmas rotate around the Earth longitudinally due to the gradient and curvature of the geomagnetic field and by the co-rotation motion with timescales from several tens of hours to less than 10 min. They interact with plasma waves at frequencies of mHz to kHz mainly in the equatorial plane of the magnetosphere, obtain energies up to MeV, and are lost into the ionosphere. In order to provide the global distribution and quantitative evaluation of the dynamical variation of these plasmas and waves in the inner magnetosphere, the PWING project (study of dynamical variation of particles and waves in the inner magnetosphere using ground-based network observations, http://www.isee.nagoya-u.ac.jp/dimr/PWING/ ) has been carried out since April 2016. This paper describes the stations and instrumentation of the PWING project. We operate all-sky airglow/aurora imagers, 64-Hz sampling induction magnetometers, 40-kHz sampling loop antennas, and 64-Hz sampling riometers at eight stations at subauroral latitudes (~ 60° geomagnetic latitude) in the northern hemisphere, as well as 100-Hz sampling EMCCD cameras at three stations. These stations are distributed longitudinally in Canada, Iceland, Finland, Russia, and Alaska to obtain the longitudinal distribution of plasmas and waves in the inner magnetosphere. This PWING longitudinal network has been developed as a part of the ERG (Arase)-ground coordinated observation network. The ERG (Arase) satellite was launched on December 20, 2016, and has been in full operation since March 2017. We will combine these ground network observations with the ERG (Arase) satellite and global modeling studies. These comprehensive datasets will contribute to the investigation of dynamical variation of particles and waves in the inner magnetosphere, which is one of the most important research topics in recent space physics, and the outcome of our research will improve safe and secure use of geospace around the Earth.

Horizontals drifts of equatorial Spread F (ESF) at post-sunset and post-midnight are investigated by analyzing six ESF events observed during the period of November 2022–March 2023. Horizontal drift velocities of ESFs are calculated from the time lags between signals recorded by different transmitter–receiver pairs of a new Continuous Doppler Sounding (CDS) system operating at 6.80 MHz in a low latitude station, Tucumán, Argentina (26° 49’ S, 65° 13' W, mag. latitude ~ 13°) and by the older CDS system working at 4.63 MHz. A new method of time lags determination for spread structures is presented. In addition, the occurrence of airglow depletions associated with ESF events is verified using images of airglow emissions of atomic O red line, 630 nm. We found that the typical speeds of the ESF drift in the post-sunset hours (around 130 m/s) are about two times greater than the speeds of ESF occurring around midnight or in post-midnight hours (around 80 m/s). The drift speeds obtained using 4.63 and 6.80 MHz systems were practically the same with the exception of one event, which might have been due to wind shear. Azimuths obtained by 4.63 and 6.80 MHz systems are almost similar. No systematic dependence of the azimuth on the local time and sounding frequency was found. All ESF events drift roughly eastward with an average azimuth of about 105 ∘ with respect to the geographic north. Graphical Abstract