Upper Atmosphere Of Mars Research Articles

Bridging Model–Data Discrepancies in Mars’ Dayside Ionosphere: Exploring Varying Reaction Rate Coefficients

Measurements of concentrations of neutral and ion species in the upper atmosphere of Mars by the Neutral Gas and Ion Mass Spectrometer (NGIMS) on board the Mars Atmosphere and Volatile EvolutioN mission have served as model input and/or for comparison with model output in numerous earlier studies of the Martian dayside ionosphere. While many models reproduce the altitudinal density profiles of key ion species within a factor of a few, it has proven challenging to achieve a level of agreement within tens of percent for multiple ion species over a wide range of altitudes. We explore means to overcome this issue while keeping with a reduced chemical model and utilizing the assumptions of photochemical equilibrium and that the NGIMS data are devoid of any measurement errors. We entertain, for instance, the idea that the rate coefficient for the charge-transfer reaction between CO2+ and O may vary with altitude as a result of a pressure-controlled internal energy distribution of the CO2+ population.

An Empirical Predictive Model for Atmospheric H Lyman‐α Emission Brightness at Mars

AbstractCharacterizing the abundance of atmospheric hydrogen (H) at Mars is critical for determining the current and, subsequently, the primordial water content on the planet. At present, the atmospheric abundance of Martian H is not directly measured but is simulated using proprietary models that are constrained with observations of H Lyman‐α emission brightness, as well as with observations of other atmospheric parameters, such as temperature and Solar UV irradiance. Publicly available brightness measurements require further processing to have scientific utility. To make the data needed to model H abundances and escape rates more accessible to the community, we use H Lyman‐α emissions made with the Mars Atmosphere and Volatile Evolution (MAVEN) mission. The near decade‐spanning data set is reduced to obtain disk‐pointed averages of the H brightness in the upper atmosphere of Mars and then analyzed for statistical trends across multiple variables. The H Lyman‐α emission brightness is found to be dependent on Solar illumination, Solar cycle, and season. The resulting data trends are used to derive empirical fits to build a predictive framework for future observations or an extrapolative tool for estimates of water content at previous epochs. Data that was intentionally not included in the empirical derivations are used to validate the predictions successfully to within 18% accuracy, on average. This first‐of‐its kind predictive model for H brightness is presented to the community and can be used with atmospheric models to further derive and interpret the abundances and escape rate of H atoms at Mars.

Retrieval of Ar, N2, O, and CO in the Martian Thermosphere Using Dayglow Limb Observations by EMM EMUS

AbstractThe Emirates Ultraviolet Spectrometer (EMUS) onboard the Emirates Mars Mission (EMM) Hope probe images Mars at wavelengths extending from approximately 100 to 170 nm. EMUS observations began in February 2021 and cover over a full Mars year. We report the first limb scan observations at Mars of ultraviolet emissions Ar I 106.6 nm, N I 120 nm, and carbon monoxide (CO) Fourth Positive Group (A − X) band system excited by electron impact on CO. We use EMUS limb scan observations to retrieve number density profiles of argon, molecular nitrogen, atomic oxygen, and CO in the upper atmosphere of Mars from 130 to 160 km. CO is a sensitive tracer of the thermal profile and winds in Mars' middle atmosphere and the chemistry that balances CO2 in the atmosphere of Mars. EMUS insertion orbit special observations demonstrate that far ultraviolet limb measurements of the Martian thermosphere can be spectroscopically analyzed with a robust retrieval algorithm to further quantify variations of CO composition in the Martian upper atmosphere.

Atmospheric Tides in the Middle and Upper Atmosphere of Mars at Northern High Latitudes: A Comparison of MAVEN‐EUVM and MRO‐MCS Observations With Model Results

AbstractMuch of the variability in the Martian thermosphere can be attributed to vertically propagating atmospheric tides that are known to achieve significant amplitudes in this region. Concurrent observations from different altitudes have been used previously to discern the vertical propagation characteristics of tides but have primarily focused on low latitudes. The spectrum of tides and their vertical evolution are thereby less constrained at high latitudes. Few studies that have focused on high latitudes identified wavenumber‐3 structures which were interpreted to originate mainly from the non‐migrating tides SE1 and DE2. This paper presents the first analysis of MAVEN‐EUVM solar occultation observations to deduce atmospheric tides in the Martian thermosphere. These are compared to tides observed by MRO‐MCS in the middle atmosphere for six cases at high northern latitudes. To identify vertical propagation, wave signatures in the middle and upper atmosphere are compared and are found to be dominated by a mix of zonal wavenumbers‐2 and ‐3 in fixed local time. MCS observations show eastward propagating tides dominate, specifically highlighting SE1 near 76 km. Additionally, these observations indicate the presence of stationary planetary waves and terdiurnal tides. Mars Climate Database also indicates the presence of SE1, DE2, DE1, S0, TW1, and T0 tides. A change in the dominant wavenumber component with local time is seen, which is attributed to the presence of all three diurnal, semidiurnal and terdiurnal components at these latitudes. The significant decrease in the diurnal tide amplitude indicates the effect of zonal mean wind on vertical propagation.

Impacts of Gravity Waves in the Martian Thermosphere: The Mars Global Ionosphere‐Thermosphere Model Coupled With a Whole Atmosphere Gravity Wave Scheme

AbstractGravity waves are a key mechanism that facilitates coupling between the lower and upper atmosphere of Mars. In order to better understand the mean, large‐scale impacts of gravity waves on the thermosphere, a modern whole atmosphere, nonlinear, non‐orographic gravity wave parameterization scheme has been incorporated into a three‐dimensional ground‐to‐exosphere Mars general circulation model, the Mars Global Ionosphere‐Thermosphere Model (M‐GITM). M‐GITM simulations utilizing the gravity wave parameterization indicate that significant gravity wave momentum is deposited in the thermosphere, especially within the altitude range of 90–170 km. This impacts the winds in the thermosphere; in particular, M‐GITM simulations show a decrease in speed of the wind maximum in the summer hemisphere by over a factor of two. Gravity wave effects also impact the temperatures above 120 km in the model, producing a cooler simulated thermosphere at most latitudes. M‐GITM results were also compared to upper atmospheric temperature and wind data sets from the MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft. Some aspects of wind data‐model comparisons improved once the gravity wave scheme was added to M‐GITM; furthermore, a cooler temperature profile produced by these new M‐GITM simulations for the MAVEN Deep Dip 2 observational campaign resulted in a closer data‐model comparison, particularly above 180 km. Overall, these modeling results show that gravity waves play an important role for the energy and momentum budget of the Martian thermosphere.

A Modeling Study of the Seasonal, Latitudinal, and Temporal Distribution of the Meteoroid Mass Input at Mars: Constraining the Deposition of Meteoric Ablated Metals in the Upper Atmosphere

This study provides a comprehensive description of the deposition of meteor-ablated metals in the upper atmosphere of Mars, accounting for the temporal, vertical, latitudinal, and seasonal distribution. For this purpose, the Leeds Chemical Ablation Model is combined with a meteoroid input function to characterize the size and velocity distributions of three distinctive meteoroid populations around Mars—the Jupiter-family comets (JFCs), main-belt asteroids, and Halley-type comets (HTCs). These modeling results show a significant midnight-to-noon enhancement of the total mass influx because of the orbital dynamics of Mars, with meteoroid impacts preferentially distributed around the equator for particles with diameters below 2000 μm. The maximum total mass input occurs between the northern winter and the first crossing of the ecliptic plane with 2.30 tons sol−1, with the JFCs being the main contributor to the overall influx with up to 56% around Mars’ equator. Similarly, total ablated atoms mainly arise from the HTCs with a maximum injection rate of 0.71 tons sol−1 spanning from perihelion to the northern winter. In contrast, the minimum mass and ablated inputs occur between the maximum vertical distance above the ecliptic plane and aphelion with 1.50 and 0.42 tons sol−1, respectively. Meteoric ablation occurs approximately in the range altitude between 100 and 60 km with a strong midnight-to-noon enhancement at equatorial latitudes. The eccentricity and the inclination of Mars’ orbit produces a significant shift of the ablation peak altitude at high latitudes as Mars moves toward, or away, from the northern/southern solstices.

Thermal Structure of the Middle and Upper Atmosphere of Mars From ACS/TGO CO2Spectroscopy

AbstractTemperature and density in the upper Martian atmosphere, above ∼100 km, are key diagnostic parameters to study processes of the species' escape, investigate the impact of solar activity, model the atmospheric circulation, and plan spacecraft descent or aerobraking maneuvers. In this paper, we report vertical profiling of carbon dioxide (CO2) density and temperature from the Atmospheric Chemistry Suite (ACS) solar occultations onboard the ExoMars Trace Gas Orbiter. A strong CO2absorption band near 2.7 μm observed by the middle infrared spectrometric channel (ACS MIR) allows the retrieval of the atmospheric thermal structure in an unprecedentedly large altitude range, from 20 to 180 km. We present the latitudinal and seasonal climatology of the thermal structure for 1.5 Martian years (MYs), from the middle of MY 34 to the end of MY 35. The results show the variability of distinct atmospheric layers, such as a mesopause (derived from 70 to 145 km) and homopause, changing from 90 to 100 km at aphelion to 120–130 km at perihelion. Some short‐term homopause fluctuations are also observed depending on the dust activity.

Solar cycle and seasonal variability of H in the upper atmosphere of Mars

The complex seasonal, dust, and atmospheric circulation patterns at Mars affect the abundance and spatial extent of water and its photo-dissociated atomic byproduct H. Recent observations by the Mars Atmosphere and Volatile Evolution (MAVEN) mission have been used to constrain the H abundance at the exobase (200 km altitude) as well as its thermal and global escape rate. The MAVEN observations span the last seven years and encompass the effects of the declining phase of Solar Cycle 24 and activating phase of Solar Cycle 25 from mid-perihelion of Mars Year (MY) 32 through most of aphelion of MY36. Results show that there are seasonal as well as solar cycle variations in H exobase temperatures, densities, thermal escape rates, and global escape rates. During perihelion of MYs 32–35, the H exobase density fluctuates with a cadence that corresponds to the approach to perihelion as well as the onset and peak of regional dust storms. Additionally, the abundance of H atoms did not show exceptional variability during the MY34 Global Dust Storm, when compared with trends from adjacent years. Seasonal averages of H exobase densities, thermal escape rates, and global escape rates indicated an order of magnitude difference between perihelion and aphelion, and suggest a water global equivalent layer range of 0.02–13 m lost over 4 billon years. H properties are also found to vary with solar cycle to a lesser extent than with seasons across the MAVEN timeline. Trends show that the exobase density varies inversely with solar activity, while both the thermal and global escape rates vary directly with solar activity. It remains to be seen if the effects of a stronger than recent solar cycle on the upper atmospheric H properties would become more pronounced.

Observations of Atmospheric Tides in the Middle and Upper Atmosphere of Mars From MAVEN and MRO.

Variability in the Martian upper atmosphere is strongly linked to the lower atmosphere and much of it can be attributed to vertical wave propagation. Atmospheric tides in particular are a well‐known phenomenon in the Martian atmosphere that play a key role in the transport of energy as they propagate to higher altitudes. Previous theoretical predictions and observations suggest that tides producing wavenumber‐2 and wavenumber‐3 patterns are strongest in a fixed local time at high altitudes, however, the energy they carry and the region of deposition are not well characterized. Given the availability of atmospheric observations from several spacecraft at the same time, in this paper, the nature and behavior of tides are studied concurrently at several altitudes. Here, six intervals are identified focused at fixed low latitudes utilizing simultaneous observations of the middle and upper atmosphere from in situ and remote sensing instruments on different spacecraft. In the middle atmosphere, strong wavenumber‐2 signatures are identified in the intervals north of the equator whereas, in the south, wavenumber‐3 signatures are strongest. Wave signatures observed in the upper atmosphere seem to be dominated by a mix of wavenumbers‐2 and ‐3. Seasonal variation is observed in the northern intervals, with very little interannual variability in all intervals considered. Estimates of energy based on dominant wavenumber amplitude suggest that most of the energy dissipates below ∼90 km. Furthermore, model sampled output captures the dominant wavenumbers observed in the middle atmosphere as well as the energy dissipation characteristics.

Influence of Magnetic Fields on Precipitating Solar Wind Hydrogen at Mars.

Solar wind protons can interact directly with the hydrogen corona of Mars through charge exchange, resulting in energetic neutral atoms (ENAs) able to penetrate deep into the upper atmosphere of Mars. ENAs can undergo multiple charge changing interactions, leading to an observable beam of penetrating protons in the upper atmosphere. We seek to characterize the behavior of these protons in the presence of magnetic fields using data collected by the Mars Atmosphere and Volatile EvolutioN spacecraft. We find that backscattered penetrating proton flux is enhanced in regions where the magnetic field strength is greater than 200 nT. We also find a strong correlation at CO2 column densities less than 5.5 × 1014 cm−2 between magnetic field strength and the observed backscattered and downward flux. We do not see significant changes in penetrating proton flux with magnetic field strengths on the order of 10 nT.

Atmospheric Loss of Atomic Oxygen during Proton Aurorae on Mars

—For the first time, the calculations of the penetration of protons of the undisturbed solar wind into the daytime atmosphere of Mars due to charge exchange in the extended hydrogen corona (Shematovich et al., 2021) are used allowing us to determine self-consistently the sources of suprathermal oxygen atoms, as well as their kinetics and transport. An additional source of hot oxygen atoms—collisions accompanied by the momentum and energy transfer from the flux of precipitating high-energy hydrogen atoms to atomic oxygen in the upper atmosphere of Mars—was included in the Boltzmann kinetic equation, which was solved with the Monte-Carlo kinetic model. As a result, the population of the hot oxygen corona of Mars has been estimated; and it has been shown that the proton aurorae are accompanied by the atmospheric loss of atomic oxygen, which is evaluated within a range of (3.5–5.8) × 107 cm–2 s–1. It has been shown that the exosphere becomes populated with a substantial amount of suprathermal oxygen atoms with kinetic energies up to the escape energy, 2 eV. The atomic oxygen loss rate caused by a sporadic source in the Martian atmosphere—the precipitation of energetic neutral atoms of hydrogen (H‑ENAs) during proton aurorae at Mars—was estimated by the self-consistent calculations according to a set of the Monte-Carlo kinetic models. These values turned out be comparable to the atomic oxygen loss supported by a regular source—the exothermic photochemical reactions (Groeller et al., 2014; Jakosky et al., 2018). It is currently supposed that the atmospheric loss of Mars due to the impact of the solar wind plasma and, in particular, the fluxes of precipitating high-energy protons and hydrogen atoms during solar flares and coronal mass ejections may play an important role in the loss of the neutral atmosphere on astronomic time scales (Jakosky et al., 2018).

Isotopic fractionation of water and its photolytic products in the atmosphere of Mars

The current Martian atmosphere is about five times more enriched in deuterium than Earth’s, providing direct testimony that Mars hosted vastly more water in its early youth than nowadays. Estimates of the total amount of water lost to space from the current mean D/H value depend on a rigorous appraisal of the relative escape between deuterated and non-deuterated water. Isotopic fractionation of D/H between the lower and the upper atmospheres of Mars has been assumed to be controlled by water condensation and photolysis, although their respective roles in influencing the proportions of atomic D and H populations have remained speculative. Here we report HDO and H2O profiles observed by the Atmospheric Chemistry Suite (ExoMars Trace Gas Orbiter) in orbit around Mars that, once combined with expected photolysis rates, reveal the prevalence of the perihelion season for the formation of atomic H and D at altitudes relevant for escape. In addition, while condensation-induced fractionation is the main driver of variations of D/H in water vapour, the differential photolysis of HDO and H2O is a more important factor in determining the isotopic composition of the dissociation products. Three years of observations with the ExoMars TGO Atmospheric Chemistry Suite have clarified the mechanism of atmospheric water loss from Mars, and particularly the fraction of deuterium compared with hydrogen. Analysis of several isotopologues of water in the mid-atmosphere of Mars shows that atomic H and D are produced at perihelion in relative amounts controlled by photolysis. These atoms are able to escape from the atmosphere.

Forbidden atomic oxygen emissions in the martian dayside upper atmosphere

Recently, Nadir and Occultation for Mars Discovery (NOMAD) ultraviolet and visible spectrometer instrument on board the European Space Agency’s ExoMars Trace Gas Orbiter (TGO) simultaneously measured the limb emission intensities for both [OI] 2972 and 5577 Å (green) emissions in the dayside of Martian upper atmosphere. But the atomic oxygen red-doublet emission lines ([OI] 6300 and 6364 Å), which are expected to be observed along with [OI] 5577 and 2972 Å emissions, are found to be absent in the NOMAD-TGO dayside observed spectra. We aim to explore the photochemistry of all these forbidden atomic oxygen emissions ([OI] 2972, 5577, 6300, 6464 Å) in the Martian daylight upper atmosphere and suitable conditions for the simultaneous detection of these emissions lines in the dayside visible spectra. A photochemical model is developed to study the production and loss processes of O(1S) and O(1D), which are the respective excited states of green and red-doublet emissions, by incorporating various chemical reactions of different O-bearing species in the upper atmosphere of Mars. By reducing Fox (2004) modelled neutral density profiles by a factor of 2, the calculated limb intensity profiles for [OI] 5577 and 2972 Å emissions are found to be consistent with the NOMAD-TGO observations. In this case, at altitudes below 120 km, our modelled limb intensity for [OI] 6300 Å emission is smaller by a factor 2 to 5 compared to that of NOMAD-TGO observation for [OI] 2972 Å emission, and above this distance it is comparable with the upper limit of the observation. We studied various parameters which can influence the limb intensities of these atomic oxygen forbidden emission lines. Our calculated limb intensity for [OI] 6300 Å emission, when the Mars is at near perihelion and for solar maximum condition, suggests that all these forbidden emissions should be observable in the NOMAD-TGO visible spectra taken on the dayside of Martian upper atmosphere. More simultaneous observations of forbidden atomic oxygen emission lines will help to understand the photochemical processes of oxygen-bearing species in the dayside Martian upper atmosphere.

Horizontal Internal Gravity Waves in the Mars Upper Atmosphere From MAVEN ACC and NGIMS Measurements

AbstractInternal gravity waves (IGWs) play an important role in the planetary atmospheres, which transfer energy and momentum from the lower layers to the upper atmosphere. However, the IGW perturbations and behaviors are not clear in the Mars upper atmosphere, particularly for the horizontal internal gravity waves (hIGWs). In this study, the hIGWs in the upper atmosphere of Mars are estimated and investigated for the first time using both accelerometer (ACC)‐derived mass density and Neutral Gas and Ion Mass Spectrometer‐measured neutral density from Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. The results show that the amplitudes of hIGWs variations are significantly affected by the dust storms and increase with the altitudes. The larger amplitudes are triggered in Martian Year (MY) 34 during a global dust event. The characteristics of Ar and CO2 hIGWs variations are similar. Furthermore, the trend of the CO perturbations seems to follow the CO2. However, the dust storms play little role in shaping hIGWs of atomic O. The hIGWs show the stable waveform with the increasing altitudes.

Temperature extraction from spacecraft density profiles in the presence of wave activity

In the absence of direct atmospheric temperature measurements, density data along spacecraft trajectories are often used to extract temperature profiles, a process that can fail in the presence of wave activity (Leclercq et al., 2020). Because spacecraft data are often not sufficient to uniquely characterize wave-like perturbations, we examine the difference between predicted and extracted temperature profiles based on linearized solutions to the wave equations and briefly discuss the relevance to wave activity in the upper atmospheres of Mars and Titan. We find that the extracted temperatures are significantly overestimated for the full range of acoustic gravity wave parameters but are somewhat underestimated for a range of internal gravity wave parameters, and the density amplitudes can serve as a proxy for the extracted temperature amplitudes when estimating the heating rates.

Solar Tides in the Middle and Upper Atmosphere of Mars

AbstractSolar tides are responsible for much of the spatial‐temporal variability of Mars' upper atmosphere (100–∼200 km). However, the tidal spectrum, its latitude versus Ls variability, and its vertical evolution remain uncertain. In this paper, Mars Climate Sounder temperature measurements at 76 km above Mars' areoid are used to construct a multiyear latitude versus Ls climatology of the tidal spectrum. The most important spectral components include the solar‐synchronous (“migrating”) components DW1, SW2, and the solar‐asynchronous (“nonmigrating”) tides DE3, DE2, DE1, SE1, S0, and SW1. The Mars Climate Database (MCD), which provides predictions from the Laboratoire de Météorologie Dynamique Global Climate Model, captures particularly well the amplitudes and key structural features of the solar‐asynchronous tides at 76 km that furthermore underly the large longitudinal structures in density that are observed between 100 and 200 km. Height‐latitude and latitude‐Ls structures of MCD density perturbations are therefore examined between 76 and 172 km and interpreted in terms of mean wind and dissipation effects. In particular, due to the smaller radius and more intense zonal‐mean zonal winds at Mars compared to Earth, Doppler‐shift effects are significantly exaggerated compared to Earth. Evidence is also provided for nonnegligible contributions to density variability from stationary planetary waves which arise from tide‐tide nonlinear interactions. It is moreover shown that MCD captures the salient amplitude and phase characteristics of the ∼±30–60% longitudinal density perturbations measured by the Mars Global Surveyor accelerometer. This, and the excellent MCD‐MCS agreement at 76 km, lends credibility to the ability of MCD to provide new insights into thermosphere density variability at Mars due to vertical coupling by solar tides.

CO+first-negative band emission: A tracer for CO in the Martian upper atmosphere

Context.Recently, the Imaging Ultraviolet Spectrograph (IUVS) on board the Mars Atmosphere and Volatile EvolutioN (MAVEN) satellite observed CO+first-negative band limb emission in the Martian upper atmosphere.Aims.We aim to explore the photochemical processes in the Martian upper atmosphere, which drive this band emission.Methods.A photochemical model was developed to study the excitation processes of CO+first-negative band emission (B2Σ+→ X2Σ+) in the upper atmosphere of Mars. The number density profiles of CO2and CO from two different models, namely, Mars Climate Database (MCD) and Mars Global Ionosphere-Thermosphere (MGIT), were used to determine the limb intensity of this band emission.Results.By increasing the CO density by a factor of 4 and 8 in MCD and MGIT models, respectively, the modelled CO+first-negative band limb intensity profile is found to be consistent with the IUVS/MAVEN observation. In this case, the intensity of this band emission is significantly determined by the ionisation of CO by solar photons and photoelectrons, and the role of dissociative ionisation of CO2is negligible.Conclusions.Since CO is the major source of the CO+(B2Σ+), we suggest that the observed CO+first-negative band emission intensity can be used to retrieve the CO density in the Martian upper atmosphere for the altitudes above 150 km.

Density Fluctuations in the Lower Thermosphere of Mars Retrieved From the ExoMars Trace Gas Orbiter (TGO) Aerobraking

The upper atmosphere of Mars is constantly perturbed by small-scale gravity waves propagating from below. As gravity waves strongly affect the large-scale dynamics and thermal state, constraining their statistical characteristics is of great importance for modeling the atmospheric circulation. We present a new data set of density perturbation amplitudes derived from accelerometer measurements during aerobraking of the European Space Agency’s Trace Gas Orbiter. The obtained data set presents features found by three previous orbiters: the lower thermosphere polar warming in the winter hemisphere, and the lack of links between gravity wave activity and topography. In addition, the orbits allowed for demonstrating a very weak diurnal variability in wave activity at high latitudes of the southern winter hemisphere for the first time. The estimated vertical damping rates of gravity waves agree well with theoretical predictions. No clear anticorrelation between perturbation amplitudes and the background temperature has been found. This indicates differences in dissipation mechanisms of gravity waves in the lower and upper thermosphere.

A user-orientated column modelling framework for efficient analyses of the Martian atmosphere

Abstract. As spacecraft missions return ever more data from Mars, additional tools will be required to explore and analyse these datasets efficiently. To streamline research into the atmosphere of Mars, a user-orientated modelling capability is developed that enables automatic initialisation and running of a column model. As a demonstration we utilise the modelling framework to provide additional verification for the University of Helsinki and Finnish Meteorological Institute Mars column model temperature profiles above the height of typical lander meteorological measurements, i.e. above 2 m. We utilise the framework at landing site locations that are well characterised to understand the model's applicability and to identify future opportunities for modifications to the framework. We do this by using the framework to compare the column model to temperature soundings made by the Mars Reconnaissance Orbiter. We find that the column model, without any modification, is able to reproduce the observed lapse rates and average temperatures closely in most cases except for a 20–60 K increase over the northern hemisphere mid-winter. We can reproduce this discrepancy by incorporating an adiabatic heating term into the column model. Fitting of the modified column model to the observations results in estimated maximum downward vertical wind velocities of ∼ 10 cm s−1 at altitudes of 15–20 km over the winter solstice at the VL-1 and VL-2 sites. The approach developed here may possibly provide a way to independently estimate or observe the vertical motion in the Martian atmosphere. However, even though the magnitude of the vertical wind speed appears reasonable, it is not clear at this point how much the atmospheric heating is due to other mechanisms such as advection. We have introduced new application software that can quickly find and display the requested data and can be immediately analysed using the included tools. We have demonstrated the potential of this type of software application with a glimpse into the upper atmosphere of Mars.

Global characteristics of gravity waves in the upper atmosphere of Mars as measured by MAVEN/NGIMS

We present an analysis of gravity waves in Mars' upper atmosphere above 120 km. Using in-situ data from NGIMS onboard MAVEN we have been able to characterise waves from nearly 4000 orbits. We have used temperature and density profiles to extract perturbations and interpret these as vertically propagating gravity waves which we characterise by their amplitude and wavelength. In this region of the atmosphere gravity waves have amplitudes of around 10%. Vertical wavelengths are found to be around 10–30 km. We observe an increase in gravity wave amplitudes with increasing solar zenith angle. Gravity wave amplitudes appear invariant in altitude on the dayside, however increase with altitude on the nightside.