Atomic Oxygen Profiles Research Articles

Raman-corrected two-photon absorption laser induced fluorescence of atomic oxygen in premixed hydrogen, cellular tubular flames

Femtosecond, Two-photon Absorption Laser Induced Fluorescence (fs-TALIF) corrected for collisional quenching with Raman scattering is used to capture spatially resolved atomic oxygen profiles in lean premixed, hydrogen cellular tubular flames. This method has allowed comparisons of number density and O-atom concentration distributions in flames of variable stretch rates in a manner similar to that previously performed on the minor flame species H and OH. As stretch rate increases, the radii of peak O-atom in the cells decrease while O-atom concentrations remain relatively unaffected. This differs from non-cellular flame data where increasing stretch rate increases minor species number densities. Three chemical mechanisms are employed to perform direct numerical simulations of the O-atom profiles in the tubular flames and are found to be in close agreement with one another. For N2-diluted flames, the simulations predict O-atom number densities within the uncertainty of the data for the cellular region but over-predict the O-atom number densities in the dearth region of the 2D flames. Additionally, simulated O-atom concentrations contradict the trend of the data and increase with stretch rate. Changing the diluent from N2 to CO2 lowers the peak concentrations of atomic oxygen as CO2 becomes reactive at flame temperatures. This allows the CO+O(+M)⇌CO2(+M) reaction to consume atomic oxygen. Flames diluted with carbon dioxide caused the model to over-predict the O-atom concentration in these flames. This discrepancy is similar to past minor species measurements in cellular tubular flames though it does not occur in minor species profiles of non-cellular (1D), CO2-diluted tubular flames. The discrepancy could be caused by the simplifying relationships employed to convert the 3D geometry to 2D in the simulations.

Specific Features of Radiation Transfer in the Hydrogen Lyman-alpha Line and Their Possible Relationship with Changes in the Electron Concentration in the Ionospheric D Region

The effect of neutral atmospheric parameters on the radiation transfer in the Lyman-alpha line and the electron concentration in the ionospheric D region is studied for various seasons and nitric oxide (NО) concentrations. The radiation transfer was calculated with a modified radiation transfer model that allows multiscattering radiation effects. The atomic hydrogen and molecular oxygen profiles affecting Lyman-alpha radiation propagation were given with the MSIS-00 model. It is shown the radiation fluxes in the Lyman-alpha line and the electron concentration in the D region can be markedly affected upon sudden stratospheric warming and by the influence of planetary waves on the mesosphere. The changes in radiation fluxes in the Lyman-alpha line under unstable atmospheric conditions in the winter and the possible NО variations qualitatively explain the phenomenon of the winter anomaly.

On the relationship between atomic oxygen and vertical shifts between OH Meinel bands originating from different vibrational levels

OH Meinel emissions from different vibrational levels are known to occur at slightly different altitudes in the terrestrial airglow. Earlier model studies suggested quenching by atomic oxygen to be a principal cause of these vertical shifts. Here we employ the tropical mesopause region—characterized by pronounced semiannual variations—as a natural laboratory to test the hypothesis that vertical shifts between different OH Meinel bands are a consequence of quenching by atomic oxygen. Nighttime satellite measurements of OH(3–1) and OH(6–2) volume emission rate profiles and atomic oxygen with Scanning Imaging Absorption Spectrometer for Atmospheric Chartography on Envisat are used for this purpose. Upper mesospheric atomic oxygen profiles are retrieved from measurements of the O(1S–1D) green line emission. The results demonstrate that vertical shifts between the OH bands investigated are indeed correlated with the amount of atomic oxygen in the upper mesosphere, corroborating the hypothesis.

Global observations of thermospheric temperature and nitric oxide from MIPAS spectra at 5.3μm

[1] We present vertically resolved thermospheric temperatures and NO abundances in terms of volume mixing ratio retrieved simultaneously from spectrally resolved 5.3 μm emissions recorded by the Michelson Interferometer for Passive Atmospheric Spectroscopy (MIPAS) in its upper atmospheric observation mode during 2005–2009. These measurements are unique since they represent the first global observations of temperature and NO for both day and night conditions taken from space. A retrieval scheme has been developed which accounts for vibrational, rotational and spin-orbit non-LTE distributions of NO. Retrieved polar temperature and NO profiles have a vertical resolution of 5–10 km for high Ap values, and degrade to 10–20 km for low Ap conditions. Though retrieved NO abundances depend strongly on the atomic oxygen profile used in the non-LTE modeling, observations can be compared to model results in a consistent manner by applying a simple correction. Apart from this, total retrieval errors are dominated by instrumental noise. The typical single measurement precision of temperature and NO abundances are 5–40 K and 10–30%, respectively, for high Ap values, increasing to 30–70 K for Tk and 20–50% for NO VMR for low Ap conditions. Temperature and NO profiles observed under auroral conditions are rather insensitive to smoothing errors related to the mapping of a priori profile shapes. However, for extra-polar and low Ap conditions, a potential systematic bias in the retrieved nighttime temperature and NO profiles related to smoothing errors has been identified from a comparison to Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME-GCM) simulations. We have constructed a solar minimum monthly climatology of thermospheric temperature and NO from MIPAS observations taken during 2008–2009. MIPAS temperature distributions agree well, on average, with the Mass Spectrometer and Incoherent Scatter radar model (NRLMSISE-00), but some systematic differences exist. MIPAS temperatures are generally colder than NRLMSISE-00 in the polar middle thermosphere (mainly in the summer polar region) by up to 40 K; and are warmer than NRLMSISE-00 in the lower thermosphere around 120–125 km by 10–40 K. Thermospheric NO daytime distributions agree well with the Nitric Oxide Empirical Model (NOEM), based on Student Nitric Oxide Explorer (SNOE) observations. A comparison of MIPAS NO number density with the previous climatology for the declining phases of the solar cycle based on HALOE and SME data shows that MIPAS is generally larger with values ranging from 10 to 40%, except in the auroral region and at the equatorial latitudes above 130 km where the MIPAS/HALOE+SME ratio varies from 1.6 to 2. Day-night differences in MIPAS NO show daytime enhancements of up to 140% in the tropical and midlatitudes middle thermosphere. In the lower thermosphere, the diurnal amplitude is smaller and NO concentrations are generally higher during night by about 10–30%, particularly in the auroral regions.

Use of O<sub>2</sub> airglow for calibrating direct atomic oxygen measurements from sounding rockets

Abstract. Accurate knowledge about the distribution of atomic oxygen is crucial for many studies of the mesosphere and lower thermosphere. Direct measurements of atomic oxygen by the resonance fluorescence technique at 130 nm have been made from many sounding rocket payloads in the past. This measurement technique yields atomic oxygen profiles with good sensitivity and altitude resolution. However, accuracy is a problem as calibration and aerodynamics make the quantitative analysis challenging. Most often, accuracies better than a factor 2 are not to be expected from direct atomic oxygen measurements. As an example, we present results from the NLTE (Non Local Thermodynamic Equilibrium) sounding rocket campaign at Esrange, Sweden, in 1998, with simultaneous O2 airglow and O resonance fluorescence measurements. O number densities are found to be consistent with the nightglow analysis, but only within the uncertainty limits of the resonance fluorescence technique. Based on these results, we here describe how better atomic oxygen number densities can be obtained by calibrating direct techniques with complementary airglow photometer measurements and detailed aerodynamic analysis. Night-time direct O measurements can be complemented by photometric detection of the O2 (b1∑g+−X3∑g-) Atmospheric Band at 762 nm, while during daytime the O2 (a1Δg−X3∑g-) Infrared Atmospheric Band at 1.27 μm can be used. The combination of a photometer and a rather simple resonance fluorescence probe can provide atomic oxygen profiles with both good accuracy and good height resolution.

The role of atomic oxygen concentration in the ionization balance of the lower ionosphere during solar proton events

Abstract. The influence of atomic oxygen concentration on the height distribution of the main positive and negative ions and on electron density in the mesosphere is studied for the conditions prevailing during the solar proton event on 17 January 2005. It is shown by numerical modeling that the electron and ion density profiles are strongly dependent on the choice of the atomic oxygen profile. Experimental measurements of the electron density are used as the criterion for choosing the atomic oxygen profile in the mesosphere. With the help of modeling, the atomic oxygen profile in the daytime in the winter mesosphere is found to lead to a model electron density profile best matching the electron density profile obtained experimentally. As a result, with the help of modeling, we find the atomic oxygen profiles at various solar zenith angles in the winter mesosphere which lead to model electron density profiles matching the electron density profiles obtained experimentally. Alteration of the atomic oxygen concentration leads to a redistribution of the abundance of both positive and negative ion constituents, with changes in their total concentrations and transition heights. In consequence this results in changes of the electron density and effective recombination coefficient. For conditions of low concentration of atomic oxygen (during a solar proton event), the formation of cluster ions is the key process determining electron and ion densities at altitudes up to 77 km. The complex negative CO3− ion is formed up to about 74 km and the final NO3− ion, which is stable in relation to the atomic oxygen, is the dominant negative ion up to 74 km. As a result the transition heights between cluster ions and molecular ions and between negative ions and electron density are located at 77 km and 66 km, respectively.

Atomic oxygen profiles (80 to 115 km) derived from Wind Imaging Interferometer/Upper Atmospheric Research Satellite measurements of the hydroxyl and greenline airglow: Local time–latitude dependence

Hydroxyl and oxygen greenline nightglow observations from the Wind Imaging Interferometer (WINDII) are used to examine the local time–latitude variation of atomic oxygen in the mesopause region. Individual hydroxyl and greenline emission profiles from over 5 years of data are converted to oxygen mixing ratio (or concentration) profiles and then binned into local times, latitudes, and seasons. The two derived oxygen profiles from each emission are then combined into a single profile that spans a significant portion of the mesopause region (80 to 115 km). A technique developed earlier that addresses the altitude variability of the emission profiles is used. This level of agreement indicates a high degree of consistency in the radiance observations and in the photochemistry used to convert the emission rates to oxygen profiles. We demonstrate that the atomic oxygen concentration or mixing ratio profiles are very sensitive to local nighttime, and we display the manner in which they vary. The local time variation is primarily due to the tidal dynamics in the atmosphere. Comparisons between our atomic oxygen data set, a simple tidal model, and the TIME‐GCM show good agreement; however, the local time tidal structure of atomic oxygen from MSISE‐90 shows a 180° phase inconsistency. The measured local time oxygen variations vary with season and latitude, and we show that these oscillations are stronger under equinox conditions.

Airglow on Mars: Some model expectations for the OH Meinel bands and the O 2 IR atmospheric band

This work presents model calculations of the diurnal airglow emissions from the OH Meinel bands and the O 2 IR atmospheric band in the neutral atmosphere of Mars. A time-dependent photochemical model of the lower atmosphere below 80 km has been developed for this purpose. Special emphasis is placed on the nightglow emissions because of their potential to characterize the atomic oxygen profile in the 50–80 km region. Unlike on Earth, the OH Meinel emission rates are very sensitive to the details of the vibrational relaxation pathway. In the sudden death and collisional cascade limits, the maximum OH Meinel column intensities for emissions originating from a fixed upper vibrational level are calculated to be about 300 R, for transitions v ′ = 9 → v ′ ⩽ 8 , and 15,000 R, for transitions v ′ = 1 → v ′ = 0 , respectively. During the daytime the 1.27 μm emission from O 2( a Δ g 1 ), primarily formed from ozone photodissociation, is of the order of MegaRayleighs (MR). Due to the long radiative lifetime of O 2( a Δ g 1 ), a luminescent remnant of the dayglow extends to the dark side for about two hours. At night, excited molecular oxygen is expected to be produced through the three body reaction O + O + CO 2. The column emission of this nighttime component of the airglow is estimated to amount to 25 kR. Both nightglow emissions, from the OH Meinel bands and the O 2 IR atmospheric band, overlap in the 50–80 km region. Photodissociation of CO 2 in the upper atmosphere and the subsequent transport of the atomic oxygen produced to the emitting layer are revealed as key factors in the nightglow emissions from these systems. The Mars 5 upper constraint for the product [H][O 3] is revised on the basis of more recent values for the emission probabilities and collisional deactivation coefficients.

A Method of Inversing the Peak Density of Atomic Oxygen Vertical Distribution in the MLT Region From the OI (557.7nm) Night Airglow Intensity

In this paper, using the MSISE-90 model as the reference atmosphere, we discuss the feasibility and method of deducing the peak densities of the undisturbed atomic oxygen profiles in the MLT region (the mesosphere and lower thermosphere region) from OI (557.7 nm) night airglow intersities. The peak densities for different seasons, latitudes and longitudes are deduced from OI (557.7nm) airglow intensities through this expression. We analyze the features of inversion relative errors and discuss the influence of the variations in temperature on inversion errors. The results indicate that all inversion errors are less than 5% except for those at high altitudes in the summer hemisphere. And the impact of the variations in temperature on errors is not significant.

Atomic oxygen annual and semi-annual variations in the mesopause region for mid and equatorial latitudes

Satellite volume emission rates of the hydroxyl airglow and the atomic oxygen greenline measured by the wind imaging interferometer (WINDII) on board the upper atmospheric research satellite (UARS) are used to infer atomic oxygen profiles in the mesopause region. The data extends during the lifetime of the instrument from late 1991 through to 1997. The atomic oxygen derived from each emission is combined to provide a climatology extending from 80 to 115 km which includes up to 15 km above and below the peak in atomic oxygen concentration. A spectral analysis is performed for each latitude/local time/altitude bin on the time series of the atomic oxygen where the measurements were taken. Annual and semi-annual variations were identified and their resulting amplitudes and phases showed strong variability as functions of altitude and latitude. A summary of the conclusions are as follows: At mid-latitudes, the atomic oxygen time series consists of both annual and semi-annual variations with amplitudes up to 50% from the mean. The maximum and minimum of the annual variation depended on the hemisphere and the altitude. At the atomic oxygen peak (about 96 km ), the amplitude of the annual variation minimized in the winter hemisphere with a change phase in 180° through the equator towards the summer hemisphere and is consistent with previous observations. The phase of these variations depends on height. Below the oxygen peak (about 87 km ), the phase of the annual variation changed by 180°. At the equator, the atomic oxygen is dominated by the semi-annual variation with maxima about a month after the equinoxes with an amplitude that is stronger than in the northern hemisphere. The mid-latitude semi-annual results are in contrast to previous observations. There is also evidence for a quasi-biennial oscillation in the mesopause region in atomic oxygen at altitudes above 95 km .

Atomic oxygen profiles (80–94 km) derived from Wind Imaging Interferometer/Upper Atmospheric Research Satellite measurements of the hydroxyl airglow: 1. Validation of technique

The use of satellite measurements of the hydroxyl airglow volume emission rate profile to infer the atomic oxygen profile of the mesopause region is complicated by uncertainties as to the collision de‐excitation mechanism and the vibration transition probabilities that are needed for the analysis. In this paper, we demonstrate that the shape of the derived atomic oxygen profiles is, to a large extent, independent of the choice of these factors. We use data from two nights of observation from the Wind Imaging Interferometer (WINDII) instrument onboard Upper Atmospheric Research Satellite (UARS) where the instrument observed the hydroxyl emission and the oxygen greenline emission on alternate orbits. The comparison between the derived atomic oxygen profiles from the two emissions is difficult because the region of overlap of good quality data lies in between the peaks and is small (about 4 km). Also, the altitude of the good overlap is not fixed but is a function of both latitude and local time and may lie anywhere in the altitude range from 88 to 94 km because the heights of the emission layers also change. We have adopted a technique of doing the comparison only at certain altitude/local time combinations depending on where the best data exists. The hydroxyl parameter set that used Goldman transition probabilities and a sudden death quenching model best fit the greenline derived atomic oxygen and will be used to complete a full atomic oxygen climatology from 80 to 110 km.

The criterion of gravity wave instability induced by photochemistry in summer polar mesopause region

This paper studies the effect of photochemistry on the gravity wave instability in summer polar mesopause region. The calculation method of the effects of eddy viscosity, conductivity and eddy diffusion of chemical species on the gravity wave instability induced by photochemistry are studied. The critical wavelength of the instability is given in this paper. The influences of some parameters on it are discussed. The study shows that the gravity wave instability induced by photochemistry is sensitive to the temperature and atomic oxygen profiles.

Odd oxygen measurements during the Noctilucent Cloud 93 rocket campaign

The NLC‐93 campaign at Esrange, Sweden, addressed the chemical, dynamical and electrical environment of the summer mesopause in the presence of noctilucent clouds (NLC). A major topic was the detailed investigation of odd oxygen abundances and their structure in the vicinity of the cloud layer. Applying independent in situ measurements, we have obtained consistent profiles of atomic oxygen, ozone, and mesospheric total density. Atomic oxygen was measured on two rocket flights by means of a newly developed probe utilizing the 1304 Å resonance fluorescence / absorption technique. Detailed Monte Carlo simulations of the radiative transfer and the instrument aerodynamics are included in the data analysis. We find relatively low atomic oxygen densities with a peak of 2 × 1011 cm−3 at 96 km. An airglow radiometer recorded the O2 IR‐atmospheric band emission, allowing the retrieval of ozone densities by means of an inversion model that considers both direct and indirect sources of O2 (a1Δg). The odd oxygen measurements are compared to a steady state photochemical model. While good agreement is found in the mesosphere, the results deviate close to the cold mesopause. Significant vertical structures are found in the atomic oxygen profiles; sharp gradients and distinct minima coincide with the observed NLC layer. Possible influences of heterogeneous chemistry on the odd oxygen abundance are discussed.

Analytical models for the responses of the mesospheric OH* and Na layers to atmospheric gravity waves

Analytic models are developed to describe gravity wave induced perturbations in the high ν OH* Meinel Band emissions and in atomic Na density. The results are used to predict the fluctuations in OH* intensity and rotational temperature, Na abundance, and the centroid heights of the OH* and Na layers. The OH* model depends critically on the assumed form for the atomic oxygen profile. In this study the O profile is modeled as a Chapman layer, which is in excellent agreement with MSIS‐90. We also neglect the wave‐induced redistribution of O3 because the chemical lifetime of ozone in the mesopause region is short compared to most gravity wave periods. Under these conditions the OH* response is ΔV/Vu ≃ −3[1 ‐ (z ‐ zOH)hOH + (z − zOH)2/σ12]Δρ/ρu, where ΔV/Vu are the relative emission rate fluctuations, Δρ/ρu are the relative atmospheric density fluctuations, zOH ≃ 89 km is the layer centroid height, hOH ≃ 3.6 km, and σ1 ≃ 8.0 km. By using these results, we show that cancellation of the induced perturbations in emission intensity and rotational temperature is significant for short vertical wavelengths. The amplitude attenuation in both parameters is proportional to exp(−m2σ2OH/2), where m = 2π/λz and σOH ≃ 4.4 km is the rms thickness of the OH* layer. For example, at λz = 15 km, the predicted rotational temperature perturbation is only 20% of the atmospheric temperature perturbation. Because the most sensitive instruments are only capable of accuracies approaching ±2 K, there are few reported observations of waves with λz ≤ 15 km. The cancellation effects are not as limiting in OH intensity observations because the relative intensity perturbations are larger than the relative temperature perturbations, and intensities can be measured more accurately than temperature, especially with broadband instruments. Fluctuations in the emission rate are largest on the bottomside of the OH* layer, ∼ 3.75 km below the layer peak (∼89 km), where the effects due to the redistribution of atomic oxygen dominate. Fluctuations in rotational temperature are largest near the peak of the OH layer, where the volume emission rate is largest. The ∼3.75 km separation between the maxima of the intensity and rotational temperature perturbations is largely responsible for the phase differences observed in the fluctuations of these parameters. Rotational temperature and Krassovsky's ratio are found to be very sensitive to the form of the background temperature profile. Wave‐induced OH* layer centroid height fluctuations coupled with the mean lapse rate of the background temperature profile can contribute significantly to the observed rotational temperature fluctuations, especially for the shorter wavelength waves λz ≤ 15 km. The OH* intensity fluctuations are relatively insensitive to the temperature profile as well as variations in atomic oxygen density and therefore appear to be excellent tracers of gravity wave dynamics. OH temperature observations are best suited for studying long‐period waves, including tides, with λz ≥ 15 km.

Gravity wave signature simultaneously observed in the oxygen atom and electron density profiles in the lower thermosphere

The fine structures of lower thermospheric atomic oxygen and electron density profiles obtained by a rocket experiment were investigated, assuming that these structures are due to a quasimonochromatic internal gravity wave. The height variation of the horizontal wind amplitude is similar to that of the intrinsic horizontal phase speed below ∼105 km, implying an evidence of saturation effects. At higher altitudes, the dissipation due to molecular diffusion was suggested. The wavy variation of the intrinsic horizontal phase speed with height can be explained by the mean wind modulation due to an atmospheric tide. The horizontal phase velocity vector inferred is interpreted as a consequence of selective transmission of internal gravity waves in lower atmosphere.

Infra‐red rocket glow: A mechanistic analysis

A two channel infra‐red radiometer observed a contaminating glow at 1.53 µm on the up and down legs of a rocket flight between 90 and 105 km. No contamination was detectable at 1.27 µm nor by broadband uv/visible photodiode photometers. The structures in the glow showed a remarkable similarity with the structures on the simultaneously measured atomic oxygen profile. We have been able to show that the glow can be successfully modelled by I ∞ [O]² v², where v is the rocket speed. This implies that two oxygen atoms arriving on the surface are involved in the production of the emitting species. It is suggested that the oxygen atoms form a molecule which is either radiatively stabilized or undergoes an association/dissociation with a surface adsorbed oxygen molecule.

A reference model for atomic oxygen in the terrestrial atmosphere

The various methods that have been used to measure, or derive, the atomic oxygen profile in the atmosphere are discussed briefly. It is suggested that while there is a very significant uncertainty in the actual concentration the natural variability may be quite large and could explain some of the reported concentration differences. Even with these limitations an Atomic Oxygen Reference model has been derived from average monthly ozone profiles and the MSIS-86 reference model atmosphere. The model concentration profiles are presented in tabular form for each month, at 10 degree latitude steps over the altitude range 40 – 130 km.

On the [formula omitted] emission rate ratio in aurora

We examine the sources of variability in the vertically integrated I(557.7 nm) I(427.8 nm) ratio of auroral green line emission to N 2 + 1 NG emission, in terms of its response to changes both in the electron energy spectrum and the atomic oxygen concentration. Assuming that N 2(A) + O and O + e are the only mechanisms producing the O( 1S) 557.7 nm emission, the emission rate ratio was modelled for varying atomic oxygen concentration and a fixed electron energy spectrum. The range of ratios obtained corresponds well with the range of observed ratios, from 1 to 10. The ratios were then computed for an MSIS atomic oxygen profile, but for electron fluxes having Maxwellian energy distributions with E 0 varying from 0.125 keV to 8 keV. The resulting ratios all lie between 5 and 6, a range that is much smaller than the observed ratio range. The curve obtained is in good agreement with coordinated ground-based and satellite observations. Through the introduction of an energy-independent ratio, it is shown that the insensitivity of the emission rate ratio to electron characteristic energy results from a balancing of the N 2(A) contribution at low altitude against the O + e contribution at high altitude, making the overall contribution relatively constant with altitude. On this basis, it is concluded that atomic oxygen variability is dominantly responsible for changes in the emission rate ratio. It is also shown that additional mechanisms are unlikely to influence this conclusion.

Interference filter spectral imaging of twilight O<sup>+</sup>(<sup>2</sup>P-<sup>2</sup>D) emission

Abstract. A spectral imager specifically designed to measure the O+(2P-2D) emission in the thermosphere during twilight has been constructed and tested in Toronto (43.8°N, 79.3°W), and found to show promise for long-term and campaign-mode operations. A modification of the mesopause oxygen rotational temperature imager (MORTI), it consists basically of a narrow-band interference filter (0.14 nm bandwidth) to separate wavelengths as a function of off-axis angle, a lens to focus the spectrum into a series of concentric rings, and a focal plane array (CCD) to record the spectral images in digital form. The instrument was built with two fields of view, one for the zenith and one for 20° above the horizon, movable to track the azimuth of the Sun, in order to provide appropriate data for inversion. Data gathered during June 1991 provided measurements of the column-integrated emission rate with a precision of about 3%. An atomic oxygen profile was deduced that showed good agreement with that predicted by the MSIS-90 model atmosphere. Geomagnetically induced variations of the O+ lines, calcium spectra resulting from meteor showers, and OH nightglow were also observed.

Gravity Wave Characteristics Derived from Structured Atomic Oxygen Profile and Multiple Es Layers.

We investigated the fine structures of lower thermospheric atomic oxygen and electron density profiles obtained by a rocket experiment, assuming that these structures are due to a quasi-monochromatic internal gravity wave. The dissipation process of a gravity wave was inferred from the atomic oxygen profile. The height variation of the horizontal wind amplitude is similar to that of the intrinsic horizontal phase speed below ∼105 km, implying an evidence of saturation effects. At higher altitudes, dissipation due to molecular diffusion was suggested. The propagation direction of the wave was determined from both atomic oxygen and electron profiles based on the fact that the response of ionic species to gravity waves is different from that of neutral species depending on the propagation direction. The propagation direction inferred is interpreted as a consequence of selective transmission of gravity waves in lower atmosphere.