OH Emission Research Articles

Inner coma of comet 67P/Churyumov–Gerasimenko during increased activity at perihelion on 22-23 August 2015

Abstract The study presents observations of the coma of comet 67P/Churyumov–Gerasimenko using the Wide Angle Camera of the OSIRIS instrument aboard the Rosetta spacecraft on August 22-23, 2015. An outburst occurred on August 22, resulting in the release of a significant amount of icy particles. The spatial distribution of CN, OH, NH, NH2, and OI emissions was analyzed. The brightness of CN emission exhibits weak dependence on position angle and distance from the nucleus, unlike other emissions, which peak strongly in the solar direction. The ability to determine the bulk density of dust particles through photometry of the shadow cast by the nucleus has been demonstrated. The distribution of the bulk density of dust particles reveals the existence of two components, each characterized by different rates of density decrease with distance from the nucleus: larger particles are located closer to the nucleus, while smaller particles dominate in the region of free expansion. In the free expansion region, the power law index describing the decrease in volumetric density of dust particles with distance is significantly greater than -2. This is attributed to the rapid fragmentation of dust resulting from the evaporation of volatile components in the free expansion area.

Discharge and emission characteristics of rotating gliding arc plasma using air, ammonia, and ammonia/air mixtures

Owing to the application limitations of ammonia as a clean energy source, plasma-assisted combustion technology has become an effective method for improving the ammonia combustion performance. In this study, the discharge characteristics of a rotating gliding arc (RGA) plasma in air, ammonia (NH3), and mixed ammonia/air gases were investigated, as well as their effects on combustion and emissions. Studies have shown that increasing the RGA plasma power enhances the stability of the gas discharge voltage and current waveforms, promotes the combustion reaction of mixed gas, and shortens the flame when a high ammonia content is present. In the ammonia discharge spectrum, NH, N2, Hα, and Hβ were primarily observed, whereas in the air discharge spectrum, NO, N2, OH, and O were mainly observed. The discharge spectrum of the mixed gas containing 10% ammonia was mainly composed of substances common to both discharges, with the intensity of the OH emissions significantly increasing as the power increased. Under varying ammonia concentrations and discharge power conditions, the introduction of the RGA plasma extended the combustion range of ammonia from 20%–25% to 15%. When the ammonia content was low (less than 15%), the NO generated by the air discharge was reduced owing to the reduction reaction of ammonia. When the ammonia content exceeded 15%, the NO concentration increased with increasing power. When the discharge power was less than 10% of the combustion power (power ratio), the NO produced was either less than or comparable to the NO generated by ammonia combustion without plasma. However, when the power ratio exceeded 10%, the combustion reaction was enhanced, leading to a sharp increase in NO emissions. The combustion reaction temperature of the mixture increased steadily as the power increased. These findings offer valuable insights into optimizing the plasma-assisted ammonia combustion process, enhancing the combustion efficiency, and minimizing pollutant emissions, thereby improving environmental sustainability.

JWST’s Sharper View of EX Lup: Cold Water from Ice Sublimation during Accretion Outbursts

Abstract The unstable accretion phases during pre-main-sequence evolution of T Tauri stars produce variable irradiation and heating of planet-forming regions. A strong accretion outburst was observed with Spitzer-InfraRed Spectrograph in 2008 in EX Lup, the prototype of EXor variables, and found to increase the mid-infrared water and OH emission and decrease organic emission, suggesting large chemical changes. We present here two JWST-MIRI epochs of quiescent EX Lup in 2022 and 2023 obtained over a decade after the 2008 outburst and several months after a moderate burst in 2022. With JWST’s sharper spectral view, we can now analyze water emission as a function of temperature in the two MIRI epochs and, approximately, also in the previous Spitzer epochs. This new analysis shows a strong cold water vapor “burst” in low-energy lines during the 2008 outburst, which we consider clear evidence for enhanced ice sublimation due to a recession of the snowline, as found in protostellar envelopes. JWST shows that EX Lup still has an unusually strong emission from cold water in comparison to other T Tauri disks, suggesting >10 yr long freeze-out timescales in the inner disk surface. EX Lup demonstrates that outbursts can significantly change the observed organic-to-water ratios and increase the cold water reservoir, providing chemical signatures to study the recent accretion history of disks. This study provides an unprecedented demonstration of the chemical evolution triggered by accretion outbursts in the class II phase and of the high potential of time-domain experiments to reveal processes that may have fundamental implications on planet-forming bodies near the snowline.

Influence of gas free stream layer on charge accumulation and hydroxyl radical production in the atmospheric pressure plasma jets

This study investigates the influence of gas free stream layer on the charge accumulation and hydroxyl radical (OH) production in the atmospheric pressure plasma jet. It is hypothesized that the inertial force of the gas free stream layer influences plasma interactions, including wall charge accumulation and air entrainment. Electrical measurements revealed that increased gas flow rate led to higher breakdown voltage, indicating reduced charge accumulation on the wall. Schlieren imaging and OH-planar laser-induced fluorescence diagnostics showed that OH generation occurs primarily at the boundary between the plasma jet and ambient air. Notably, a linear correlation was observed between the simulated free stream layer and the OH emission boundary gap, suggesting that the gas free stream layer critically affects air entrainment for OH production. These findings provide insight into optimizing gas flow conditions for enhanced OH production and discharge in atmospheric plasma jets.

Chemiluminescence emissions of OH measured at different positions during flame propagation of H2/CH4 mixtures explosion

Chemiluminescence emissions of OH measured at different positions during flame propagation of H2/CH4 mixtures explosion

Emissions Characteristics of OH During H2/CH4/Air Mixtures Explosion in a 20 L Closed Tank

To study the emission intensity of OH during H2/CH4/air mixtures explosion, experiments were performed inside a 20 L spherical closed tank. The pressure history and flame propagation characteristics of H2/CH4/air mixtures explosion were recorded and analyzed. The effects of the volume fraction of hydrogen and equivalence ratio on explosion pressure, flame radius, and emission intensity of OH were surveyed. The results show that after α > 0.6, hydrogen started to take a leading role in the explosion pressure and flame propagation of H2/CH4/air mixtures. The effect on the high equivalence ratio of H2/CH4/air mixtures is more obvious, which makes the reaction of H2/CH4/air mixtures explosion faster and more dangerous. The emission intensity of OH at 308.9 nm is strongest, with 282.8 nm being the earliest and 347.2 nm being the latest. As the volume fraction of hydrogen increases, the Imax and (dI/dt)max of OH continue to increase, and at a higher equivalence ratio, the Imax of OH begins to rise sharply from α = 0.6. As the equivalence ratio increases, Imax and (dI/dt)max of OH increase first and then decrease. The important sources of OH emissions in the H2/CH4/air mixtures explosion are the reaction of R38 and the reverse reaction of R84.

First Search for Pulsed CH Maser Emission Stimulated by a Pulsar

Abstract We present the first search for pulsed CH maser emission potentially stimulated by PSR J1644-4559, conducted using the ultra-wide-bandwidth low-frequency receiver on Murriyang, CSIRO's Parkes Radio Telescope. Observations targeted three CH Λ-doublet transitions at 3264, 3335, and 3349 MHz, with a variability timescale of 78 ms. We detected ten CH emission features at 3335 and 3349 MHz, and seven features at 3264 MHz, during both pulsar-ON and pulsar-OFF phases. The observed velocities align with the OH emission and absorption reported by a previous study, suggesting a close spatial association between CH and OH molecules. The derived column densities for CH clouds within the Parkes beam range from 0.05 to 9.8 × 1013 cm−2, indicating that these clouds are likely in diffuse and translucent states. Upper limits for CH column densities within the pulsar beam ranged from 0.3 to 9.8 × 1013 cm−2. Comparison of these column densities suggests that CH clouds may exhibit clumpiness and substructure. No significant stimulated emission feature was detected in the optical depth spectra. Additionally, as part of our search for pulsed stimulated emission, we investigated the potential CH absorption of the pulsar signal and found none, in agreement with astrophysical expectations. The upper limits for the potential maser amplification factors towards PSR J1644-4559 at 3264, 3335, and 3349 MHz are 1.014, 1.009, and 1.009, respectively. This study demonstrates the feasibility of detecting pulsed CH maser emission in the interstellar medium stimulated by pulsar photons.

MINDS. JWST-MIRI reveals a peculiar CO2-rich chemistry in the drift-dominated disk CX Tau

Context. Radial drift of icy pebbles can have a large impact on the chemistry of the inner regions of protoplanetary disks, where most terrestrial planets are thought to form. Disks with compact millimeter dust emission (≲50 au) are suggested to have a higher H2O flux than more extended disks, as well as show excess cold H2O emission, likely due to efficient radial drift bringing H2O-rich material to the inner disk, where it can be observed with IR facilities such as the James Webb Space Telescope (JWST). Aims. We present JWST MIRI/MRS observations of the disk around the low-mass T Tauri star CX Tau (M2.5, 0.37 M⊙) taken as a part of the Mid-INfrared Disk Survey (MINDS) GTO program, a prime example of a drift-dominated disk based on ALMA data. In the context of compact disks, this disk seems peculiar: the source possesses a bright CO2 feature instead of the bright H2O that could perhaps be expected based on the efficient radial drift. We aim to provide an explanation for this finding in the context of the radial drift of ices and the disk’s physical structure. Methods. We modeled the molecular features in the spectrum using local thermodynamic equilibrium (LTE) 0D slab models, which allowed us to obtain estimates of the temperature, column density, and emitting area of the emission. Results. We detect molecular emission from H2O, 12CO2, 13CO2, C2H2, HCN, and OH in this disk, and even demonstrate a potential detection of CO 18O emission. Analysis of the 12CO2 and 13CO2 emission shows the former to be optically thick and tracing a temperature of ∼450 K at an (equivalent) emitting radius of ∼0.05 au. The optically thinner isotopologue traces significantly colder temperatures (∼200 K) and a larger emitting area. Both the ro-vibrational bands of H2O at shorter wavelengths and its pure rotational bands at longer wavelengths are securely detected. Both sets of lines are optically thick, tracing a similar temperature of ∼500–600 K and emitting area as the CO2 emission. We also find evidence for an even colder, ∼200 K H2O component at longer wavelengths, which is in line with this disk having strong radial drift. We also find evidence of highly excited rotational OH emission at 9–11 µm, known as “prompt emission”, caused by H2O photodissociation. Additionally, we firmly detect four pure rotational lines of H2, which show evidence of extended emission. Finally, we also detect several H recombination lines and the [Ne II] line. Conclusions. The cold temperatures found for both the 13CO2 and H2O emission at longer wavelengths indicate that the radial drift of ices likely plays an important role in setting the chemistry of the inner disk of CX Tau. The H2O-rich gas has potentially already advected onto the central star, which is now followed by an enhancement of comparatively CO2-rich gas reaching the inner disk, explaining the enhancement of CO2 emission in CX Tau. The comparatively weaker H2O emission can be explained by the source’s low accretion luminosity. Alternatively, the presence of a small, inner cavity with a size of roughly 2 au in radius, outside the H2O iceline, could explain the bright CO2 emission. Higher angular resolution ALMA observations are needed to test this.

Dissociative excitation of acetone induced by electron impact

Abstract We report the results of an experimental study focused on the low-energy (10–100 eV) electron impact excitation of acetone. In the emission spectrum, the most prominent excited species were found to be the hydrogen Balmer series, the excited CH radical in the A and B electronic states, and atomic carbon. The presence of OH emission in the spectra confirms the tautomerization process induced by electron impact. The acetone emission spectra were measured at several different reaction energies, forming a unique 3D spectral electron energy map. Excitation-emission functions were extracted for selected most prominent products and corresponding threshold energies were determined.

Study of H<sub>2</sub>O and OH Masers in the Region Formation of a Young High Mass Stellar Object (S255 NIRS 3)

The results of a study of a star formation region are presented. S255 IR, where a young high-mass star is forming (20M•). Observations in H2O were carried out on RT-22 in Pushchino, and in the OH lines at the Large Radio Telescope in Nance (France). Data observations in the H2O line at 1.35 cm were used for the period 2017–2023. Our observations in H2O showed the existence strong flares, especially in 2023. Drift was also observed emission by radial velocity for most spectral details and predominantly in the direction of decreasing radial velocity. In OH lines 18 cm in 2008 no emission was detected. We observed OH emission in the main lines 1665 and 1667 MHz in 2015, 2023 and 2024. Structures of spectra, degrees of circular and linear polarizations varied greatly during these epoch. However, at the same time the longitudinal magnetic field vectors had predominantly two directions: relative to the vertical, i. e. almost perpendicular to the jet or along it. Zeeman splitting was detected only in the 1667 MHz line for one pair of features: 2.26 and 2.37 km/s. The amount of splitting 0.11 km/s corresponds to a longitudinal magnetic field value of 0.31 mGs; the field is directed towards the observer. It is assumed that the appearance of OH maser emission in 2015 associated with an accretion flares. Significant structure changes OH spectra, their degrees of polarization and very strong flares H2O maser in 2023 may be associated with a new possibility accretion flares in S255 IR.

A detailed kinetic submechanism for OH* chemiluminescence in hydrocarbon combustion

A detailed kinetic submechanism for OH* chemiluminescence in hydrocarbon combustion

The salty emission of the intermediate-mass AGB star OH 30.1−0.7

ABSTRACT We analyse continuum and molecular emission, observed with Atacama Large Millimetre/submillimetre Array, from the dust-enshrouded intermediate-mass asymptotic giant branch (AGB) star OH 30.1−0.7. We find a secondary peak in the continuum maps, ‘feature B’, separated by 4.6 arcsec from the AGB star, which corresponds to a projected separation of $1.8\times 10^{4}$ au, placing a lower limit on the physical separation. This feature is most likely composed of cold dust and is likely to be ejecta associated with the AGB star, though we cannot rule out that it is a background object. The molecular emission we detect includes lines of CO, SiS, CS, $\mathrm{SO}_2$, NS, NaCl, and KCl. We find that the NS emission is off centre and arranged along an axis perpendicular to the direction of feature B, indicative of a UV-emitting binary companion (e.g. a G-type main sequence star or hotter), perhaps on an eccentric orbit, contributing to its formation. However, the NaCl and KCl emission constrain the nature of that companion to not be hotter than a late B-type main-sequence star. We find relatively warm emission arising from the inner wind and detect several vibrationally excited lines of SiS ($\upsilon =1$), NaCl (up to $\upsilon =4$), and KCl (up to $\upsilon =2$), and emission from low-energy levels in the mid to outer envelope, as traced by $\mathrm{SO}_2$. The CO emission is abruptly truncated around 3.5 arcsec or 14 000 au from the continuum peak, suggesting that mass loss at a high rate may have commenced as little as 2800 yr ago.

Chemiluminescence spectra investigation of ammonia flame over a wide-range equivalence ratios in a rapid compression machine

Chemiluminescence spectra investigation of ammonia flame over a wide-range equivalence ratios in a rapid compression machine

OH mid-infrared emission as a diagnostic of H2O UV photodissociation

Context. The Mid-InfraRed Instrument (MIRI) on board the James Webb Space Telescope (JWST) gives unique access to the physical and chemical structure of inner disks (<10 au), where the majority of the planets are forming. However, the interpretation of mid-infrared (mid-IR) spectra requires detailed thermo-chemical models able to provide synthetic spectra readily comparable to spectroscopic observations. This is particularly important for OH, which can be excited by a number of processes. Aims. Our goal is to explore the potential of mid-IR emission of OH to probe H2O photodissociation, and thus implicitly the far-ultraviolet (FUV) radiation field in the inner disks. Methods. We include in the DALI disk model prompt emission of OH following photodissociation of H2O in its B~ electronic state by photons at λ < 144 nm. Compared with previous modeling work, we also take into account the propensity of forming OH in the A′ symmetric states. This model allows us to compute in a self-consistent manner the thermal and chemical structure of the disk and the resulting mid-IR line intensities of OH and H2O. Results. The OH line intensities in the 9–13 μm range are proportional to the total amount of water photodissociated in the disk. As such, these OH lines are a sensitive tracer of the amount of H2O exposed to the FUV field, which depends on the temperature, density, and strength of the FUV field reaching the upper molecular layers. In particular, we show that the OH line fluxes primarily scale with the FUV field emitted by the central star in contrast with H2O lines in the 10–20 μm range which scale with the bolometric luminosity. OH is therefore an important diagnostic to probe the effect of Lyα and constrain the dust FUV opacity in upper molecular layers. A strong asymmetry between the A′ and A″ components of each rotational quadruplet is predicted. Conclusions. OH mid-IR emission is a powerful tool to probe H2O photodissociation and infer the physical conditions in disk atmospheres. As such, the inclusion of OH mid-IR lines in the analysis of JWST-MIRI spectra will be crucial for robustly inferring the chemical composition of planet-forming disks. The interpretation of less excited OH lines in the MIRI-MRS range requires additional quantum calculations of the formation pumping of OH (ro-)vibrational levels by O+H2 and the collisional rate coefficients.

FAST Detection of OH Emission in the Carbon-rich Planetary Nebula NGC 7027

We present the first detection of the ground-state OH emission line at 1612 MHz toward the prototypical carbon-rich planetary nebula (PN) NGC 7027, utilizing the newly installed ultrawideband (UWB) receiver of the Five-hundred-meter Aperture Spherical radio Telescope (FAST). This emission is likely to originate from the interface of the neutral shell and the ionized region. The other three ground-state OH lines at 1665, 1667, and 1721 MHz are observed in absorption and have velocities well matched with that of HCO+ absorption. We infer that the OH absorption is from the outer shell of NGC 7027, although the possibility that they are associated with a foreground cloud cannot be completely ruled out. All the OH lines exhibit a single blueshifted component with respect to the central star. The formation of OH in carbon-rich environments might be via photodissociation-induced chemical processes. Our observations offer significant constraints for chemical simulations, and they underscore the potent capability of the UWB receiver of FAST to search for nascent PNe.

Manifestation of the normal intensity distribution law (NIDL) in the rovibrational emission spectrum of hydroxyl radical

The latest experimental [Noll et al. Atmos. Chem. Phys. 20, 5269 (2020)] and theoretical [Brooke et al. J. Quant. Spectr. Rad. Transfer 168, 142 (2016)] data on the OH emission intensities are analysed with use of the NIDL. It is found that the calculated intensities of the Δ v > 6 transitions should not be trusted. The analysis of the OH data revealed that the NIDL theory is not applicable to the satellite bands. The effect of small reduced mass previously discovered in H 2 [Ushakov et al. J. Mol. Spectrosc. 399, 111863 (2024)], causing the NIDL straight-line slope to be larger than the one associated with the repulsive branch of the potential, is demonstrated in OH, and the same should be true of all the diatomic hydrides. We performed ab initio calculations of the OH repulsive branch and compared it with the one of Brooke et al. and the other due to Varandas and Voronin [Chem. Phys. 194, 91 (1995)]. We found that the ab initio PEF closely follows the Varandas-Voronin potential in the repulsive region important for calculating the overtone intensities [Medvedev, J. Chem. Phys. 137, 174307 (2012)].

Light Emission from Fe2+-EGTA-H2O2 System Depends on the pH of the Reaction Milieu within the Range That May Occur in Cells of the Human Body.

A Fe2+-EGTA(ethylene glycol-bis (β-aminoethyl ether)-N,N,N',N'-tetraacetic acid)-H2O2 system emits photons, and quenching this chemiluminescence can be used for determination of anti-hydroxyl radical (•OH) activity of various compounds. The generation of •OH and light emission due to oxidative damage to EGTA may depend on the buffer and pH of the reaction milieu. In this study, we evaluated the effect of pH from 6.0 to 7.4 (that may occur in human cells) stabilized with 10 mM phosphate buffer (main intracellular buffer) on a chemiluminescence signal and the ratio of this signal to noise (light emission from medium alone). The highest signal (4698 ± 583 RLU) and signal-to-noise ratio (9.7 ± 1.5) were noted for pH 6.6. Lower and higher pH caused suppression of these variables to 2696 ± 292 RLU, 4.0 ± 0.8 at pH 6.2 and to 3946 ± 558 RLU, 5.0 ± 1.5 at pH 7.4, respectively. The following processes may explain these observations: enhancement and inhibition of •OH production in lower and higher pH; formation of insoluble Fe(OH)3 at neutral and alkaline environments; augmentation of •OH production by phosphates at weakly acidic and neutral environments; and decreased regeneration of Fe2+-EGTA in an acidic environment. Fe2+-EGTA-H2O2 system in 10 mM phosphate buffer pH 6.6 seems optimal for the determination of anti-•OH activity.

FASHI: A Search for Extragalactic OH Megamasers with FAST

The FAST All Sky H i survey (FASHI) is broader in frequency band and sky volume, and deeper in detection sensitivity than the Arecibo Legacy Fast ALFA survey. To efficiently expand the sample of OH megamasers (OHMs), whose strongest line has a rest frequency of 1667.35903 MHz, we directly matched the IRAS Point Source Catalog Redshift (PSCz) catalog with the corresponding FASHI data cube. From 145 PSCz sources already covered by FASHI, we obtained 27 OHMs with a detection rate of 18.6%, including 9 previously known and 18 new ones, within a redshift range of 0.14314 ≲ z OH ≲ 0.27656. We also measured the hyperfine ratio of nine OHMs between the 1667 and 1665 MHz lines. The ratio ranges from 1.32 to 15.22, with an average of R 1667:1665 = 4.74. In a fit to the L OH versus L FIR relation, we have logLOH=(1.57±0.10)logLFIR−(15.80±1.19) , which is almost the same as derived from previous observations. As expected, since the OHM sample was selected by cross correlation with the IRAS-selected PSCz, our detected OHMs are (ultra)luminous infrared galaxies ((U)LIRGs). However, not all (U)LIRGs have detectable OH emission, suggesting that the OH emission may be triggered within a specific stage of the merger or can only be seen in specific orientations. In general, FAST, with its 19-beam array and Ultra-Wide Bandwidth receiver, will be a powerful tool for observing more OHMs and unraveling their mystery in the future.

Development of efficient nonthermal atmospheric-pressure Ar-plasma jet through simultaneous spectroscopic characterization and radical quantification

The work investigates the correlation between the plasma characteristics and reactive chemical species generation in an Ar-nonthermal atmospheric pressure plasma-jet (Ar-NTAPPJ) under various operating conditions such as gas flow rate, excitation voltage, and electrode gap and demonstrates the application of such understanding in developing efficient nonthermal plasma systems. The critical plasma parameters such as electron temperature (T e) and electron density (n e) under the various operating conditions were estimated using optical emission spectroscopy coupled with the collision radiative model and Stark broadening methods. At optimal setting of 5 LPM gas flow rate, 4 kV excitation voltage, and 6 mm electrode gap resulted in maximum T e (0.6 eV), enhancing •OH production (0.056 mM) in the liquid phase and OH(A-X) emission in the gas phase, highlighting the significance of operating conditions on building energy efficient plasma systems. The enhanced performance of the optimized Ar-NTAPPJ is demonstrated by taking atrazine as a model herbicide. The degradation performance data was correlated and validated with results obtained from spectroscopic diagnostics. By adequately tuning the operating parameters, four times enhancement in energy yield (∼150 mg kWh−1) was obtained without perturbing the nonthermal plasma mode. In nonthermal mode, to best of the authors knowledge, it is the highest reported energy yield for atrazine degradation. The scalability aspect of the present plasma jet was also investigated by Intensified Charge-Coupled Device camera-based imaging technique. The study establishes the importance of adequate diagnostics in developing efficient next-generation plasma reactors.

Wind comparisons between meteor radar and Doppler shifts in airglow emissions using field-widened Michelson interferometers

Abstract. Upper-atmosphere winds from a meteor radar and a field-widened Michelson interferometer, co-located at the Polar Environment Atmospheric Research Laboratory in Eureka, Nunavut, Canada (80° N, 86° W) are compared. The two instruments implement different wind-measuring techniques at similar heights and have very different temporal and spatial observational footprints. The meteor radar provides winds averaged over a ∼ 300 km horizontal area in 3 km vertical bins between 82 and 97 km on a 1 h cadence. The E-Region Wind Interferometer II (ERWIN) provides airglow-weighted winds (averaged over volumes of ∼ 8 km in height by ∼ 5 km radius) from three nightglow emissions (O(1S), oxygen green line, 557.7 nm, 97 km; an O2 line, 866 nm, 94 km; and an OH line, 843 nm, 87 km) on a ∼ 5 min cadence. ERWIN's higher precision (1–2 m s−1 for the O(1S) and OH emissions and ∼ 4 m s−1 for the O2 emissions) and higher cadence allows more substantive comparisons between winds measured by meteor radar and Doppler shifts in airglow emissions than previously possible for similar meteor radar/airglow Doppler shift comparisons using Fabry–Perot interferometers. The best correlation is achieved using Gaussian weighting of meteor radar winds with peak height and vertical width being optimally determined. Peak heights agree well with co-located SABER airglow observations. Offsets between the two instruments are ∼ 1–2 m s−1 for the O2 and O(1S) emissions and less than 0.3 m s−1 for the OH emission. Wind directions are highly correlated with a ∼ 1:1 correspondence. On average, meteor radar wind magnitudes are ∼ 40 % larger than those from ERWIN. Gravity wave airglow brightness weighting of observations is discussed. Non-quadrature phase offsets between the airglow weighting and gravity wave associated wind and temperature perturbations will result in enhanced or reduced layer-weighted wind amplitudes.