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The Mars NO and the O2nightglow are produced by the recombination of atoms produced on the dayside by photodissociation and transported to the nightside. These emissions are tracers of the summer to winter pole dynamics in the upper Mars atmosphere. The UV‐visible (UVIS) channel of the Nadir and Occultation for MArs Discovery (NOMAD) spectrometer onboard Trace Gas Orbiter (TGO) is the first instrument able to simultaneously monitor both nightglow emissions. Observations by NOMAD/UVIS during the first part of the Martian year show that both the NO and O2nightglow emissions are enhanced near the southern winter pole. Their mean brightnesses are 15 and 108 kR, respectively. These nightglow emissions generally occur between 30 and 60 km, the NO emitting layer being consistently located ∼10 km higher than the O2nightglow layer. Numerical simulations with the Mars Planetary Climate Model (MPCM, v6.1) properly reproduce the nightglow brightness but tend to overestimate the NO peak altitude by ∼10 km. These results suggest that the atomic oxygen density is correctly predicted by the model but that the nitrogen density altitude distribution might not be properly modeled. Nightside emissions of the Martian upper atmosphere are excited by the recombination of atoms created on the dayside. For the first time, the NO ultraviolet emission and the O2visible emission have been observed simultaneously with the UV‐visible (UVIS) channel of the Nadir and Occultation for MArs Discovery (NOMAD) spectrometer onboard Trace Gas Orbiter (TGO). They are used as tracers of the atmospheric dynamics to demonstrate the summer to winter pole circulation that governs the Mars upper atmosphere. We show that the two nightglow layers occur between 30 and 60 km and that they are separated by ∼10 km. We compare our results with simulations from the Mars Planetary Climate Model. Simulations manage to properly reproduce the nightglow brightness but tend to overestimate the NO peak altitude by ∼10 km. These results suggest that the atomic oxygen density is correctly predicted by the model but that the altitude distribution of the nitrogen density might not be properly modeled. For the first time, NOMAD/UVIS simultaneously monitors both the NO UV and O2visible nightglow in the Mars southern winter atmosphereThe NO emitting layer is consistently located ∼10 km above the O2nightglow layer (∼55 and ∼45 km, respectively)Brightness is overall well predicted but the altitude difference between the two polar emission layers is overestimated by the MPCM v6.1 model For the first time, NOMAD/UVIS simultaneously monitors both the NO UV and O2visible nightglow in the Mars southern winter atmosphere The NO emitting layer is consistently located ∼10 km above the O2nightglow layer (∼55 and ∼45 km, respectively) Brightness is overall well predicted but the altitude difference between the two polar emission layers is overestimated by the MPCM v6.1 model

The detection of hydrogen chloride (HCl) in the atmosphere of Mars was among the primary objectives of the ExoMars Trace Gas Orbiter (TGO) mission. Its discovery using the Atmospheric Chemistry Suite mid‐infrared channel (ACS MIR) showed a distinct seasonality and possible link to dust activity. This paper is part 2 of a study investigating the link between HCl and aerosols by comparing gas measurements made with TGO to dust and water ice opacities measured with the Mars Climate Sounder (MCS). In part 1, we showed, and compared, the seasonal evolution of vertical profiles of HCl, water vapor, temperature, dust opacity, and water ice opacity over the dusty periods around perihelion (solar longitudes 180°–360°) across Mars years 34–36. In part 2, we investigated the quantitative correlations in the vertical distribution between each quantity, as well as ozone. We show that there is a strong positive correlation between HCl and water vapor, which is expected due to fast photochemical production rates for HCl when reacting with water vapor photolysis products. We also show a strong positive correlation between water vapor and temperature, but are unable to show any correlation between temperature and HCl. There are weak correlations between the opacities of dust and water ice, and dust and water vapor, but only very low correlations between dust and HCl. We close with a discussion of possible sources and sinks and that interactions between HCl and water ice are the most likely for both, given the inter‐comparison. The ExoMars Trace Gas Orbiter (TGO) has observed three Martian dusty seasons (summer in the southern hemisphere). In mid‐2018, we made the first detection of hydrogen chloride (HCl) in the Martian atmosphere using the Atmospheric Chemistry Suite (ACS). Finding this gas, among others, was a priority of ExoMars because its primary source may be volcanic. Since then, we have observed two more dusty periods with the reappearance of HCl each time. In part 1, we presented the climatology of HCl over these three dusty periods (in Mars years 34, 35, and 36) and investigate their relationships with temperature and water vapor measured by ACS, and with airborne dust and water ice measured with the Mars Climate Sounder (MCS) on the Mars Reconnaissance Orbiter (MRO). In this paper, part 2, we quantify the correlations between HCl, water vapor, ozone, dust, temperature, and water ice. We show that HCl is closely correlated to water vapor, which is, in turn, correlated to temperature. There is only a very low correlation between HCl and dust or water ice, which both impact water vapor. Possible mechanisms for seasonal HCl production and destruction are discussed, concluding that the freeze‐thaw cycle of atmospheric water is most likely. Comparison of trace gases and aerosol opacity between ACS on ExoMars TGO and MCS on MROLow correlations between HCl and the opacities of dust or water ice, but very strong correlation with water vapor and the formation of icesHCl source and sink possibilities are discussed, concluding that frost activity may be the most likely possibility for both Comparison of trace gases and aerosol opacity between ACS on ExoMars TGO and MCS on MRO Low correlations between HCl and the opacities of dust or water ice, but very strong correlation with water vapor and the formation of ices HCl source and sink possibilities are discussed, concluding that frost activity may be the most likely possibility for both

Detecting trace gases such as hydrogen chloride (HCl) in Mars' atmosphere is among the primary objectives of the ExoMars Trace Gas Orbiter (TGO) mission. Terrestrially, HCl is closely associated with active volcanic activity, so its detection on Mars was expected to point to some form of active magmatism/outgassing. However, after its discovery using the mid‐infrared channel of the TGO Atmospheric Chemistry Suite (ACS MIR), a clear seasonality was observed, beginning with a sudden increase in HCl abundance from below detection limits to 1–3 ppbv in both hemispheres coincident with the start of dust activity, followed by very sudden and rapid loss at the southern autumnal equinox. In this study, we have investigated the relationship between HCl and atmospheric dust by making comparisons in the vertical distribution of gases measured with ACS and aerosols measured co‐located with the Mars Climate Sounder (MCS). This study includes HCl, water vapor, and ozone measured using ACS MIR, water vapor and temperature measured with the near infrared channel of ACS, and temperature, dust opacity, and water ice opacity measured with MCS. In part 1, we show that dust loading has a strong impact in temperature, which controls the abundance of water ice and water vapor, and that HCl is very closely linked to water activity. In part 2, we investigate the quantitative correlations between each quantity and discuss the possible source and sinks of HCl, their likelihood given the correlations, and any issues arising from them. After four full Martian years in orbit since 2018, the ExoMars Trace Gas Orbiter (TGO) has observed three Martian dusty seasons, which occur when it is spring and summer in the southern hemisphere. The first, starting in summer 2018, featured a global dust storm (GDS) after which we made the first detection of hydrogen chloride (HCl) in the Martian atmosphere using the Atmospheric Chemistry Suite (ACS) instrument. Finding this gas was a priority of ExoMars because its presence may indicate that the planet is volcanically active. Since then, we have observed two more dusty periods without a GDS and observed the reappearance of HCl each time. Here, we present the climatology of HCl in both hemispheres over these three dusty periods (in Mars years 34, 35, and 36) and investigate their relationships with temperature and water vapor measured by ACS, and with airborne dust and water ice measured with the Mars Climate Sounder (MCS) on the Mars Reconnaissance Orbiter (MRO). In this paper, we examine how the vertical structure of each quantity changes over time. We show that there is a close relationship between HCl and H2O, and that both are controlled by temperature, driven by dust loading. Comparison of trace gas abundance and aerosol extinction between Atmospheric Chemistry Suite on ExoMars TGO and Mars Climate Sounder on Mars Reconnaissance OrbiterReveal the seasonal changes in hydrogen chloride on MarsShow that dust affects atmospheric temperature, which controls water vapor abundance and ice extinction, and thus impacts HCl abundance Comparison of trace gas abundance and aerosol extinction between Atmospheric Chemistry Suite on ExoMars TGO and Mars Climate Sounder on Mars Reconnaissance Orbiter Reveal the seasonal changes in hydrogen chloride on Mars Show that dust affects atmospheric temperature, which controls water vapor abundance and ice extinction, and thus impacts HCl abundance

Ozone simulated in Mars Global Climate Models (MGCMs) is used to assess the underlying chemistry occurring in the atmosphere. Currently, ozone total column abundance (TCA) is under‐predicted in MGCMs by up to 120%, implying missing or inaccurate chemistry in models. Heterogeneous reactions of hydroxyl radicals (HOX) have been offered as an explanation for some of this bias, because they cause ozone to increase at locations where it's currently under‐predicted. We use four simulations to compare modeled ozone TCA with observations from the UVIS spectrometer aboard the ExoMars Trace Gas Orbiter to improve the representation of heterogeneous processes and their impact on ozone. We use a gas‐phase only run, a dissociative scheme, an adsorbed HOXretention scheme, and a hybrid scheme that combines the dissociative mechanism with the retention of HOXon water ice. We find retention of HOXis dependent on water ice sublimation, and ozone abundance increases when water ice persists for longer periods (1–20 sols). Over time, the loss of HOXcauses a depletion in H2O2concentration (HOXreservoir), and thus allows ozone concentration to increase. When adsorbed HOXare desorbed and dissociate into other by‐products, HOXare not immediately available to destroy ozone. This results in larger ozone concentrations than if desorbed HOXare released directly back into their gaseous states. When using the hybrid scheme, ozone TCA is increased up to 50% where the ozone deficit is greatest, demonstrating the best agreement with observations, and implying that HOXradicals are both retained when adsorbed and dissociate. Ozone is a trace gas in the martian atmosphere, sensitive to chemical and light‐induced reactions. This makes it ideal for assessing the underlying reactions for chemical species called hydroxyl radicals, which destroy ozone and would otherwise be too reactive and shortlived to be measured directly. There has been an under‐prediction of ozone in global climate models which implies missing or inaccurate reactions. Heterogeneous reactions (a reaction which includes two or more phases) have been suggested to fill the deficit in modeled ozone. This involves hydroxyl radicals adsorbing onto water ice, which causes ozone to increase. We look at different simulations to understand hydroxyl radical chemistry on the surface of water ice by comparing to observations from the ExoMars Trace Gas Orbiter. We run four climate model simulations to test different theories as to what is occurring at the surface. There are two theories (a) reactions happen at the surface which alter hydroxyl radicals into other chemicals, and (b) hydroxyl radicals stay adsorbed onto water ice for as long as the ice persists. When we combine these theories, we have a more accurate prediction of ozone, which we can then use to infer what happens at the surface. Heterogeneous reactions can have a major impact on martian ozone abundance at locations where water ice clouds persist for several solsLifetime of adsorbed hydroxyl radicals depends on water ice sublimation and longer lifetimes result in a greater abundance of ozoneA combination of longer lifetimes and dissociation of adsorbed HOXsuppresses gaseous HOXand improves simulated ozone total column abundance Heterogeneous reactions can have a major impact on martian ozone abundance at locations where water ice clouds persist for several sols Lifetime of adsorbed hydroxyl radicals depends on water ice sublimation and longer lifetimes result in a greater abundance of ozone A combination of longer lifetimes and dissociation of adsorbed HOXsuppresses gaseous HOXand improves simulated ozone total column abundance

Carbon monoxide (CO) is the main product of CO2photolysis in the Martian atmosphere. Production of CO is balanced by its loss reaction with OH, which recycles CO into CO2. CO is therefore a sensitive tracer of the OH-catalysed chemistry that contributes to the stability of CO2in the atmosphere of Mars. To date, CO has been measured only in terms of vertically integrated column abundances, and the upper atmosphere, where CO is produced, is largely unconstrained by observations. Here we report vertical profiles of CO from 10 to 120?km, and from a broad range of latitudes, inferred from the Atmospheric Chemistry Suite on board the ExoMars Trace Gas Orbiter. At solar longitudes 164–190°, we observe an equatorial CO mixing ratio of ~1,000?ppmv (10–80?km), increasing towards the polar regions to more than 3,000?ppmv under the influence of downward transport of CO from the upper atmosphere, providing a view of the Hadley cell circulation at Mars’s equinox. Observations also cover the 2018 global dust storm, during which we observe a prominent depletion in the CO mixing ratio up to 100?km. This is indicative of increased CO oxidation in a context of unusually large high-altitude water vapour, boosting OH abundance.

The Imaging UltraViolet Spectrograph (IUVS) instrument of the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has acquired data on Mars for more than one Martian year. During this time, beginning with March 2015, hundreds of stellar occultations have been observed, in 12 dedicated occultation campaigns, executed on average every 2 to 3 months. The occultations cover the latitudes from 80°S to 75°N and the full range longitude and local times with relatively sparse sampling. From these measurements we retrieve CO2, O2, and O3number densities as well as temperature profiles in the altitude range from 20 to 160 km, covering 8 orders of magnitude in pressure from ∼2 × 101to ∼4 × 10−7Pa. These data constrain the composition and thermal structure of the atmosphere. The O2mixing ratios retrieved during this study show a high variability from 1.5 × 10−3to 6 × 10−3; however, the mean value seems to be constant with solar longitude. We detect ozone between 20 and 60 km. In many profiles there is a well‐defined peak between 30 and 40 km with a maximum density of 1–2 ×109cm−3. Examination of the vertical temperature profiles reveals substantial disagreement with models, with observed temperatures both warmer and colder than predicted. Examination of the altitude profiles of density perturbations and their variation with longitude shows structured atmospheric perturbations at altitudes above 100 km that are likely nonmigrating tides. These perturbations are dominated by zonal wave numbers 2 and 3 with amplitudes greater than 45%. The execution of MAVEN/IUVS stellar occultation campaigns and the retrieval process to infer physical quantities are described in detailDistribution of molecular oxygen and ozone is measuredHighly structured atmospheric perturbations are interpreted as atmospheric tides

The article focuses on the study which examines the use of molecules from gallic acid to avoid enlarged and clogged facial pores and protect against oxidative stress and excess sebum. Topics include the factors contributing to the formation of facial pores, the antioxidant properties of trihydroxybenzoic acid glucoside (THBG) molecule and their possible impact to facial pores, and the efficacy of THBG in protecting the skin against DNA lession caused by ultraviolet (UV) irradiation.

We report observations of Martian mesospheric ice clouds and thermospheric scale heights by the Imaging Ultraviolet Spectrograph on NASA's Mars Atmosphere and Volatile Evolution mission. The clouds are observed between 6 A.M. and 8 A.M. local time using mid‐UV limb observations between 60 and 80 km tangent altitude where ice particles that scatter sunlight can appear as detached layers near the equator. The equatorial longitudinal distribution shows populations of clouds near −110°E and −10°E as well as a population near 90°E, which does not have a clear precedent. The cloud populations indicate a wave 3 pattern near 70 km, which is confirmed by independent mesospheric temperature observations. Scale heights 100 km above the clouds derived from concurrent Imaging Ultraviolet Spectrograph (IUVS) observations also reveal a wave 3 longitudinal structure, suggesting that the temperature oscillations enabling the formation of mesospheric clouds couple to the upper atmosphere. The manuscript describes the observation of Martian mesospheric clouds between 60 and 80 km altitude by the Imaging Ultraviolet Spectrograph (IUVS) on NASA's MAVEN spacecraft. The cloud observations are uniquely obtained at early morning local times, which complement previous observations obtained primarily later in the diurnal cycle. Differences in the geographic distribution of the clouds from IUVS observations indicate that the local time is crucial for the interpretation of mesospheric cloud formation. We also report concurrent observations of upper atmospheric scale heights near 170 km altitude, which are diagnostic of temperature. These observations suggest that the dynamics enabling the formation of mesospheric clouds propagate all the way to the upper atmosphere. Martian mesospheric clouds are observed by solar scattering of midultraviolet sunlight from a fully illuminated atmosphereThe early morning mesospheric cloud observations are complementary to previous observations, which are primarily made in the afternoonThe data suggest that the geographic distribution of clouds is controlled by tides that propagate all the way to the upper atmosphere

We report results from a study of nitric oxide nightglow over the northern hemisphere of Mars during winter, the southern hemisphere during fall equinox, and equatorial latitudes during summer in the northern hemisphere based on observations of the δand γbands between 190 and 270 nm by the Imaging UltraViolet Spectrograph (IUVS) on the Mars Atmosphere and Volatile EvolutioN mission (MAVEN) spacecraft. The emission reveals recombination of N and O atoms dissociated on the dayside of Mars and transported to the nightside. We characterize the brightness (from 0.2 to 30 kR) and altitude (from 40 to 115 km) of the NO nightglow layer, as well as its topside scale height (mean of 11 km). We show the possible impact of atmospheric waves forcing longitudinal variability, associated with an increased brightness by a factor of 3 in the 140–200° longitude region in the northern hemisphere winter and in the −102° to −48° longitude region at summer. Such impact to the NO nightglow at Mars was not seen before. Quantitative comparison with calculations of the LMD‐MGCM (Laboratoire de Météorologie Dynamique‐Mars Global Climate Model) suggests that the model globally reproduces the trends of the NO nightglow emission and its seasonal variation and also indicates large discrepancies (up to a factor 50 fainter in the model) in northern winter at low to middle latitudes. This suggests that the predicted transport is too efficient toward the night winter pole in the thermosphere by ∼20° latitude north. We study nitric oxide nightglow at equinox, summer, and winter and compare to the LMD‐MGCM predictionsThis study reveals the seasonal control on the emission, as well as unexpected longitudinal variations caused by waves/tidesWe suggest future work on NO nightglow using GCMs and IUVS disk images and tangent limb data

Stellar occultation measurements conducted by the Mars Atmosphere and Volatile and EvolutioN/Imaging UltraViolet Spectrograph instrument were able to make vertically resolved measurements of ozone density in the middle atmosphere of Mars that offered good coverage with respect to latitude, longitude, and local time. These measurements were used to identify systematic variations in the vertical structure of ozone with longitude that could be distinguished from general trends in the evolution of ozone with respect to season and latitude. A total of 583 individual nightside occultations between Martian years 32 and 36 were analyzed, of which 224 were confirmed to have ozone, all found between Ls= 15°–165°. Close to aphelion (Ls= 60°–90°), peak ozone densities between 30 and 40 km altitude were observed to be within error of model predictions at all measured latitudes, but diverged from model predictions before and after this time. At low latitudes, seasonal changes were seen to have the greatest effect on the observed vertical structure of ozone, with detached ozone layer densities at altitudes above 30 km usually varying within approximately a factor of two along a given latitudinal band at a given time of year. Nonetheless, evidence of a persistent regional enhancement of ozone abundance was observed over equatorial latitudes during the aphelion season, spanning a longitude range of approximately 50°–130°E longitude. Planetary waves were clearly observed at higher Southern latitudes during Southern winter, often resulting in order of magnitude variations in ozone density with longitude. The presence of ozone is key to the stability of carbon dioxide in the Martian atmosphere, and can also be used to monitor Martian meteorology. Previous measurements of vertical variations of ozone in the Martian atmosphere relied on orbiters designed mostly to look for latitudinal and seasonal trends in ozone on Mars, with little information on how ozone varies with longitude. We used data from the Imaging UltraViolet Spectrograph instrument on board the Mars Atmosphere and Volatile and EvolutioN orbiter to make independent measurements of seasonal, latitudinal, longitudinal, and altitudinal variations of ozone in the Martian atmosphere from March 2015 to January 2022. Close to the Equator of Mars, ozone tended to vary more with season than with longitude. Nonetheless, we observed a region of increased ozone densities in the Eastern hemisphere of Mars, centered over the Equator. This region was consistently seen during the same season of each observed Martian year. At higher latitudes, variations with longitude tended to be much larger and more important than seasonal variations. Variations in ozone also exhibited wave structures at Southern subpolar latitudes, possibly indicating meteorological patterns in the middle atmosphere of Mars. The first study is presented distinguishing zonal variations in vertical ozone structure on Mars from seasonal and meridional trendsOzone variability is mostly driven by seasonal changes in the tropics but by zonal circulation patterns at higher latitudesPersistent regional enhancements in mesospheric ozone are observed at equatorial latitudes during aphelion season The first study is presented distinguishing zonal variations in vertical ozone structure on Mars from seasonal and meridional trends Ozone variability is mostly driven by seasonal changes in the tropics but by zonal circulation patterns at higher latitudes Persistent regional enhancements in mesospheric ozone are observed at equatorial latitudes during aphelion season

Même si depuis 18 mois, le SARS-Cov2 a fait disparaître toute trace des virus respiratoires hivernaux historiques, les virus de la grippe, responsables de plusieurs pandémies durant le 20esiècle et d’une mortalité non négligeable, restent un sujet d’étude d’actualité. De nombreux travaux ont étudié la réaction immune innée post infection grippale mais sous un angle quantitatif en terme cellulaire et cytokinique. Le développement de technologie de microscopie moderne permettant d’étudier un organe entier en profondeur en conservant une excellente résolution mérite d’être évaluée. Peu de données sont disponibles sur l’intérêt de la M2P dans l’exploration du poumon et aucune sur son intérêt dans l’exploration des mécanismes immunitaires post infection grippale. Le but de ce travail est donc d’étudier l’intérêt de la M2P dans l’exploration des dommages structurales pulmonaires et du recrutement cellulaire après infection par le virus de la grippe d’un modèle murin.

We report a comprehensive study of Mars dayglow observations focusing on upper atmospheric structure and seasonal variability. We analyzed 744 vertical brightness profiles comprised of ∼109,300 spectra obtained with the Imaging Ultraviolet Spectrograph (IUVS) aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) satellite. The dayglow emission spectra show features similar to previous UV measurements at Mars. We find a significant drop in thermospheric scale height and temperature between LS= 218° and LS= 337–352°, attributed primarily to the decrease in solar activity and increase in heliocentric distance. We report the detection of a second, low‐altitude peak in the emission profile of OI 297.2 nm, confirmation of the prediction that the absorption of solar Lyman alpha emission is an important energy source there. The CO2+UV doublet peak intensity is well correlated with simultaneous observations of solar 17–22 nm irradiance at Mars. Significant drop in thermospheric temperature between two Martian seasonsDetection of second layer of OI 297.2 nm emission below 100 kmStrong correlation between observed mid‐UV dayglow and simultaneously measured EUV flux at Mars

We identify molecular nitrogen (N2) emissions in the Martian upper atmosphere using the Imaging Ultraviolet Spectrograph (IUVS) on NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. We report the first observations of the N2Lyman‐Birge‐Hopfield (LBH) bands at Mars and confirm the tentative identification of the N2Vegard‐Kaplan (VK) bands. We retrieve N2density profiles from the VK limb emissions and compare calculated limb radiances between 90 and 210 km against both observations and predictions from a Mars general circulation model (GCM). Contrary to earlier analyses using other satellite data, we find that N2abundances exceed GCM results by about a factor of 2 at 130 km but are in agreement at 150 km. The analysis and interpretation are enabled by a linear regression method used to extract components of UV spectra from IUVS limb observations. N2detected in the upper atmosphere of Mars by IUVS on MAVENTentative identification of N2Vegard‐Kaplan band emission confirmedN2Lyman‐Birge‐Hopfield bands identified on Mars for the first time

We present direct number density retrievals of carbon dioxide (CO2) and molecular nitrogen (N2) for the upper atmosphere of Mars using limb scan observations during October and November 2014 by the Imaging Ultraviolet Spectrograph on board NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. We use retrieved CO2densities to derive temperature variability between 170 and 220 km. Analysis of the data shows (1) low‐mid latitude northern hemisphere CO2densities at 170 km vary by a factor of about 2.5, (2) on average, the N2/CO2increases from 0.042 ± 0.017 at 130 km to 0.12 ± 0.06 at 200 km, and (3) the mean upper atmospheric temperature is 324 ± 22 K for local times near 14:00. Retrieved CO2densities at 170 km vary by a factor of about 2.5On average, N2/CO2increases from 4% at 130 km to 12% at 200 kmMean Martian upper atmospheric temperature over the sampled time frame is 324 {±} 22 K

The first campaign of stellar occultations with the Imaging Ultraviolet Spectrograph (IUVS) instrument on board of Mars Atmosphere and Volatile EvolutioN (MAVEN) mission was executed between 24 and 26 March 2015. From this campaign 13 occultations are used to retrieve CO2and O2number densities in the altitude range between 100 and 150 km. Observations probe primarily the low‐latitude regions on the nightside of the planet, just past the dawn and dusk terminator. Calculation of temperature from the CO2density profiles reveals that the lower thermosphere is significantly cooler than predicted by the models in the Mars Climate Database. A systematically cold layer with temperatures of 105–120 K is seen in the occultations at a pressure level around 7 × 10−6Pa. First results of FUV stellar occultations taken with the IUVS instrument onboard MAVENTemperature profiles reveals that the lower thermosphere is significantly cooler than predictedDetection of CO2and O2number densities

The mid‐infrared channel of the Atmospheric Chemistry Suite (ACS MIR) onboard the ExoMars Trace Gas Orbiter is capable of observing the infrared absorption of ozone (O3) in the atmosphere of Mars. During solar occulations, the 003←000 band (3,000‐3,060 cm−1) is observed with spectral sampling of ∼0.045 cm−1. Around the equinoxes in both hemispheres and over the southern winters, we regularly observe around 200–500 ppbv of O3below 30 km. The warm southern summers, near perihelion, produce enough atmospheric moisture that O3is not detectable at all, and observations are rare even at high northern latitudes. During the northern summers, water vapor is restricted to below 10 km, and an O3layer (100–300 ppbv) is visible between 20 and 30 km. At this same time, the aphelion cloud belt forms, condensing water vapor and allowing O3to build up between 30 and 40 km. A comparison to vertical profiles of water vapor and temperature in each season reveals that water vapor abundance is controlled by atmospheric temperature, and H2O and O3are anti‐correlated as expected. When the atmosphere cools, over time or over altitude, water vapor condenses (observed as a reduction in its mixing ratio) and the production of odd hydrogen species is reduced, which allows O3to build up. Conversely, warmer temperatures lead to water vapor enhancements and ozone loss. The LMD Mars Global Climate Model is able to reproduce vertical structure and seasonal changes of temperature, H2O, and O3that we observe. However, the observed O3abundance is larger by factors between 2 and 6, indicating important differences in the rate of odd‐hydrogen photochemistry. Ozone on Mars is part of the so‐called odd‐oxygen family of reactive, oxidizing gases. It is part of many chemical cycles that help convert one type of gas into another, facilitating the transfer of carbon or hydrogen. Odd‐oxygen is crucial to linking the cycles of water vapor and carbon dioxide, or the destruction of trace gases, such as methane. With the Atmospheric Chemistry Suite onboard the ExoMars Trace Gas Orbiter, we are able to study the vertical structure of ozone in the Martian atmosphere and make direct comparisons between it and water vapor and temperature. We have observed ozone abundances several times larger than predicted, suggesting that the oxidizing power of the Martian atmosphere is stronger or faster than expected. We have also observed and measured the relationship between these products: temperature controls the abundance of water vapor, and when the atmosphere cools and water condenses, ozone is able to build up. It is the by‐products of when water vapor breaks down in sunlight that remove odd‐oxygen from the atmosphere. Observations of the vertical distribution of ozone on Mars over 3 yearsDirect comparison of water vapor, ozone, and temperature, revealing trends and correlationsOzone is observed in higher abundances than photochemical models predict Observations of the vertical distribution of ozone on Mars over 3 years Direct comparison of water vapor, ozone, and temperature, revealing trends and correlations Ozone is observed in higher abundances than photochemical models predict

The Nadir and Occultation for MArs Discovery (NOMAD)/UV‐visible (UVIS) spectrometer on the ExoMars Trace Gas Orbiter provided observations of ozone (O3) and water vapor in the global dust storm of 2018. Here we show in detail, using advanced data filtering and chemical modeling, how Martian O3in the middle atmosphere was destroyed during the dust storm. In data taken exactly 1 year later when no dust storm occurred, the normal situation had been reestablished. The model simulates how water vapor is transported to high altitudes and latitudes in the storm, where it photolyzes to form odd hydrogen species that catalyze O3. O3destruction is simulated at all latitudes and up to 100 km, except near the surface where it increases. The simulations also predict a strong increase in the photochemical production of atomic hydrogen in the middle atmosphere, consistent with the enhanced hydrogen escape observed in the upper atmosphere during global dust storms. Global dust storms are rare but impactful events on Mars, occurring about once in a decade. Previous investigations found how water vapor is redistributed throughout the entire atmosphere in a dust storm. Photolysis of water vapor by sunlight produces highly reactive species that destroy ozone (O3). Here we present O3measurements taken by the NOMAD/UVIS instrument on the ExoMars Trace Gas Orbiter in the 2018 global dust storm. After advanced data filtering, they demonstrate how O3in the middle atmosphere was much reduced compared to one Mars year later when no dust storm occurred. 3D atmospheric model simulations of atmospheric chemistry in the global dust storm confirm this planet‐wide O3destruction, and help to understand the involved processes. The simulations also predict a strong increase in production of atomic hydrogen in the middle atmosphere, that can explain the observed increased hydrogen atmospheric escape during global dust storms. NOMAD ozone (O3) data filtering during the 2018 global dust storm shows strong O3destruction compared to one year later with no dust storm3D simulations of atmospheric chemistry in the 2018 global dust storm are presented to understand impact on odd hydrogen and odd oxygenThe model confirms middle‐atmospheric O3destruction in the dust storm and predicts increased photochemical production of hydrogen NOMAD ozone (O3) data filtering during the 2018 global dust storm shows strong O3destruction compared to one year later with no dust storm 3D simulations of atmospheric chemistry in the 2018 global dust storm are presented to understand impact on odd hydrogen and odd oxygen The model confirms middle‐atmospheric O3destruction in the dust storm and predicts increased photochemical production of hydrogen

Water escape on Mars has recently undergone a paradigm shift with the discovery of unexpected seasonal variations in the population of hydrogen atoms in the exosphere where thermal escape occurs and results in water lost to space. This discovery led to the hypothesis that, contradicting the accepted pathway, atomic hydrogen in the exosphere was not only produced by molecular hydrogen but mostly by high altitude water vapor. Enhanced presence of water at high altitude during southern spring and summer, due to atmospheric warming and intensified transport, favors production of H through photon‐induced ion chemistry of water molecules and thus appears to be the main cause of the observed seasonal variability in escaping hydrogen. This hypothesis is supported by the observation of large concentrations of water vapor between 50 and 150 km during the southern summer solstice and global dust events. Using a simplified yet representative air parcel transport model, we show that in addition to the formation of atomic hydrogen from water photolysis above 80 km, a major fraction of the exospheric hydrogen is formed at altitudes as low as 60 km and is then directly advected to the upper atmosphere. Comparing the injection modes of a variety of events (global dust storm, perihelion periods, and regional storm), we conclude that southern spring/summer controls H production and further ascent into the upper atmosphere on the long term with direct implication for water escape. Numerous lines of evidence suggest that Mars' water inventory was much larger in the past than it is today. The loss of this inventory has been driven by the formation of hydrated minerals on the surface, as well as by the escape of water to space. The first part of the escape process comprises the formation of H atoms, which may escape the planet once they reach the uppermost layers of the atmosphere. Here, we investigate one mechanism by which the H atoms may reach these high altitudes: the breakdown of water molecules by solar ultraviolet photons in the middle atmosphere (60–70 km above the surface), and the posterior ascent of the newly formed H atoms to the upper altitudes. We use a model that reveals that this process is the dominant contributor of atomic H to the upper atmosphere during periods of strong atmospheric circulation. In particular, we find that this mechanism is most efficient during the spring/summer season in the Southern Hemisphere, when Mars is closest to the Sun. Given that this season occurs every Martian year, our calculations suggest that this process has been the dominant contributor to water escape in the long term. We decipher hydrogen production and migration to Mars' upper atmosphere using a box model for a variety of elevated water vapor casesH atoms formed between 60 and 80 km supply a dominant fraction of hydrogen to the upper atmosphereOur results suggest that perihelion climate has a key role in the hydrogen transfer to the upper atmosphere overall We decipher hydrogen production and migration to Mars' upper atmosphere using a box model for a variety of elevated water vapor cases H atoms formed between 60 and 80 km supply a dominant fraction of hydrogen to the upper atmosphere Our results suggest that perihelion climate has a key role in the hydrogen transfer to the upper atmosphere overall

Lipases/esterases represent one of the most important classes of industrial biocatalysts due to their ability to catalyze reactions in organic media. These enzymes fulfill many important industrial specifications such as chemoselectivity, regioselectivity and stereoselectivity. The recent use of thermostable enzymes opens novel perspectives in applications involving poorly soluble substrates (or products), such as the synthesis of specialty intermediates for cosmetics. In order to discover novel thermostable esterases we have screened various thermophilic microorganisms selected within the Archaeaand the Bacteriadomains using CLIPS‐O™ substrates. One of these strains which showed activity at very high temperature was selected and the corresponding esterase gene was cloned and characterized. After recombinant expression optimization, a complete production process of this thermophilic esterase was developed, turning a ‘gene discovery’ into a biocatalyst available for industry.

We have characterized a new gene, SWI1, involved in sister chromatid cohesion during both male and female meiosis in Arabidopsis thaliana. A first allele, swi1.1, was obtained as a T-DNA tagged mutant and was described previously as abnormal exclusively in female meiosis. We have isolated a new allele, swi1.2, which is defective for both male and female meiosis. In swi1.2 male meiosis, the classical steps of prophase were not observed, especially because homologs do not synapse. Chromatid arms and centromeres lost their cohesion in a stepwise manner before metaphase I, and 20 chromatids instead of five bivalents were seen at the metaphase plate, which was followed by an aberrant segregation. In contrast, swi1.2 female meiocytes performed a mitotic-like division instead of meiosis, indicating a distinct role for SWI1 or a different effect of the loss of SWI1 function in both processes. The SWI1 gene was cloned; the putative SWI1 protein did not show strong similarity to any known protein. Plants transformed with a SWI1-GFP fusion indicated that SWI1 protein is present in meiocyte nuclei, before meiosis and at a very early stage of prophase. Thus, SWI1 appears to be a novel protein involved in chromatid cohesion establishment and in chromosome structure during meiosis, but with clear differences between male and female meiosis.

Surface films are obtained on Hg0.79Cd0.21Te and CdTe by treatment in a solution of 0.1M Fe(CN)63−(ferricyanide) in 0.5M KOH. Composition profiles are obtained by X-ray photoelectron spectroscopy (XPS), and they reveal the presence of cadmium oxide (CdO) and elemental tellurium (Te0). The film on Hg0.79Cd0.21Te is porous and thick (e.g. 800Å), whereas the film on CdTe is nonporous and thin (<100Å). The presence of CdO instead of Cd(OH)2and the presence of Te0despite the highly oxidizing Fe(CN)63−ions are not predicted by equilibrium thermodynamics; they are due to the film growth kinetics. The origin of the surface chemical films is discussed in detail.

Abstract:: Proton-π0 coincidences have been measured at the beam energy of 180A MeV in the reaction Ar+Ca studied by TAPS at SIS/GSI. In the proton-π0 invariant mass spectrum we observe a significant excess of strength above the background obtained by event mixing. We attribute this signal to the strength distribution N Δ of the Δ baryonic resonance. No correlation is observed in the case of deuteron-π0 coincidences. Assuming isotropic emission of π0 and Δ+ from a midrapidity thermal source and isospin symmetry, we determined the global N Δ/N πratio of 0.79 �0.30(stat) �0.2(syst). This value indicates that most pions produced at subthreshold energy in heavy-ion reaction are mediated by the Δ-resonance.

AbstractTetracycline‐controlled expression plasmids that allow inducible expression of proteins in mammalian cells (Gossen & Bujard, 1992), have been used to express porcine interferon‐γ in the RK‐13 rabbit kidney cell line. Following neomycin selection, stable clones produced recombinant, glycosylated porcine interferon‐γ (rGPoIFN‐γ) only after removal of tetracycline (Tc). Southern blot analysis of one clone showed that approximately 50 copies of IFN‐γ cDNA were present in the cell genome. In the absence of Tc, stable clones secreted large amounts of rGPoIFN‐γ (up to 16 μg/ml) into the medium supplemented with 10% FCS and high glucose concentration. Molecular weight comparison of 35S‐Methionine, labelled rGPoIFN‐γ with natural leukocytic IFN‐γ after immunoprecipitation, revealed 4 major glycoforms with apparent Mr of 27,000; 25,000; 20,000 and 18,500, that are almost identical in both IFN‐γ species. In both cases, all 4 glycoforms resolved into 2 polypeptide monomers with apparent Mr of 16,500 and 14,500 upon deglycosylation with N‐glycosydase F. The biological activity of rGPoIFN‐γ was in the same range as that of natural leukocytic PoIFN‐γ (2 × 106U/mg). Eventually, this recombinant mammalian IFN‐γ should constitute a very useful substitute for leukocyte PoIFN‐γ in in vitroor in vivoexperiments.

In cats, dogs and rats, clonidine (20.0 μg/Kg, i.v.) reduced the sustained tachycardia evoked by a continuous electrical stimulation of cardiac sympathetic nerve fibres. This effect of clonidine resulting from stimulation of cardiac presynaptic α-adrenoceptors could be completely antagonized by phentolatnine and prazosin in the dog and the cat, whereas in the rat, prazosin, unlike phentolamine, failed to effectively inhibit the clonidine induced reduction in heart rate. The calculated doses of phentolamine and prazosin needed to produce a 50% antagonism were of similar magnitude in the dog, but in the cat prazosin was about three times less potent than phentolamine.As opposed to clonidine, LD 3098, a potent vascular postsynaptic α-adrenoceptor stimulating imidazoline, and phenylephrine (20.0 μg/Kg, i.v.) did not significantly alter the sympathetic tachycardia in the pithed rat and the spinal dog.These results indicate that compounds stimulating postsynaptic α-adrenoceptors may be inactive as agonists of cardiac presynaptic α-adrenoceptors within the same animal species. Furthermore, a compound showing selective activity as an antagonist of vascular α-adrenoceptors in one species may not necessarily exert the same selective effects in other animals as demonstrated here for prazosin.

Hard photon production was investigated in the system 68Kr+natNi at 60 AMeV for a wide range of impact parameters. The parameters characteristic of hard photon emission such as source velocities, angular distributions and energy spectra were studied from peripheral to central collisions. The energy spectrum is seen to be strongly dependent on the centrality of the collision reflecting both a static and dynamic momentum distribution of the nucleons inside the collision zone.

Starch gel electrophoresis was used to assess isozyme polymorphism in two Manihot species. Crude extracts were obtained from leaves and pollen. Ten enzymes were examined for their polymorphism in a germplasm collection of 365 cultivated plus 109 wild accessions, mainly from Africa. The inheritance of these enzymes was examined using 13 intra and interspecific progenies. Seventeen polymorphic loci were found for the ten enzyme systems, with 59 alleles. All the markers showed disomic heredity and three linkage groups were identified.

Isozyme diversity is described among a collection of 365 Manihot esculenta cultivars plus 109 accessions from wild relatives (M. glaziovii and spontaneous hybrids) from Africa. The study is based on 17 polymorphic loci. A natural hybrid swarm is detected between the two species. Although they were recently introduced, M. esculenta and M. glaziovii show high levels of polymorphism: heterozygosity estimates are 0.225 and 0.252 respectively. For the wild species, diversity is structured at the unilocus level, and the multilocus approach reveals a geographical pattern. The organization of the diversity is not so clear for the cultivated cassava, but a multilocus approach, based on both common and rare alleles, led us to identify different groups of clones with many intermediate genotypes between them. Elements of the secondary diversification process of Manihot in Ivory Coast are discussed.

TEM-35 (inhibitor resistant TEM (IRT)-4) and TEM-36 (IRT-7) clavulanic acid-resistant beta-lactamases have evolved from TEM-1 beta-lactamase by two substitutions: a methionine to a leucine or a valine at position 69 and an asparagine to an aspartic acid at position 276. The substitutions at position 69 have previously been shown to be responsible for the resistance to clavulanic acid, and they are the only mutations encountered in TEM-33 (IRT-5) and TEM-34 (IRT-6). However, the N276D substitution has never been found alone in inhibitor-resistant beta-lactamases, and its role in resistance to clavulanic acid was thus unclear. The N276D mutant was constructed, purified, and kinetically characterized. It was shown that the substitution has a direct effect on substrate affinities and leads to slightly decreased catalytic efficiencies and that clavulanic acid becomes a poor substrate of the enzyme. Electrospray mass spectrometry demonstrated the simultaneous presence of free and inhibited enzymes after incubation with clavulanic acid and showed that a cleaved moiety of clavulanic acid leads to the formation of the major inactive complex. The kinetic properties of the N276D mutant could be linked to a salt-bridge interaction of aspartic acid 276 with arginine 244 that alters the electrostatic properties in the substrate binding area.

Summary.Antiviral activities present in uterine flushings from pregnant Large White, Large White 'hyperprolific', and prolific Meishan gilts, between Days 8 and 20 of gestation were compared. Flushings (20 ml) from all gilts between Days 14 and 20 were positive in an in-vitro interferon (IFN) assay using vesicular stomatitis virus as a challenge infection. Highest antiviral activities (of up to 400 000–1 200 000 total Units/flushing) were obtained at Day 16 of gestation, i.e. clearly after the beginning of attachment. There was no major difference between breeds although, at Day 14, flushings from Meishan gilts yielded significantly higher titres than those from the other two, suggesting a correlation with the previously described earlier trophoblast elongation in Meishan gilts. Conceptus cultures contained antiviral activity, with values very close to those obtained in vivo, but the difference between breeds was not significant. Cultures from Day 20 on contained very little antiviral activity. The antiviral activity was associated with a mixture of at least two IFNs, one of which was IFN-alpha like, and the other was serologically identified as an IFN-gamma, that is an 'immune IFN', previously found to be secreted only by T lymphocytes. This finding may have implications for our understanding of the immunology of early pregnancy.Keywords:pig; conceptus; attachment; antiviral activity; immune interferon

Clonal variation for rust resistance was studied in a factorial mating design of Populus trichocarpa and P. deltoides with 17 intraspecific and 15 interspecific progenies. Susceptibility to Melampsora larici-populina was assessed both under natural conditions in the nursery and after leaf-disk inoculation with two pathogen races in a controlled environment. Different components of the resistance were taken into account: immunity in the field or in the laboratory, latent period, number and size of uredia in the laboratory, and field resistance at the end of the growing season. Genes controlling immunity were contributed only by the P. deltoides parents. The distributions of clonal means within each family suggested a polygenic inheritance of field resistance in the P. trichocarpa x P. trichocarpa crosses, but major gene effects were suspected in the interspecific progenies. Inefficiency of the quantitative mechanisms of resistance in the interspecific F1 hybrids might have important implications for future breeding strategies. Field and laboratory trials complemented each other well, and a combined selection approach is proposed.

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Hydrogen chloride (HCl) was recently discovered in the atmosphere of Mars by two spectrometers onboard the ExoMars Trace Gas Orbiter. The reported detection made in Martian Year 34 was transient, present several months after the global dust storm during the southern summer season. Here, we present the full data set of vertically resolved HCl detections obtained by the NOMAD instrument, which covers also Martian year 35. We show that the particular increase of HCl abundances in the southern summer season is annually repeated, and that the formation of HCl is independent from a global dust storm event. We also find that the vertical distribution of HCl is strikingly similar to that of water vapor, which suggests that the uptake by water ice clouds plays an important role. The observed rapid decrease of HCl abundances at the end of the southern summer would require a strong sink independent of photochemical loss. A new species, hydrogen chloride (HCl), was recently discovered in the atmosphere Mars. Whereas, this gas plays a key role in the atmospheric chemistry on Earth and Venus, the chlorine cycle on Mars is not understood. HCl was found just after the global dust storm, so a connection between the storm and appearance of HCl was suggested. This study shows that HCl is detected even in a year without a global dust storm, which demonstrates that the formation of HCl is primary independent from global dust storms. This study also finds that the vertical distributions of HCl and water vapor are strikingly similar in shape. As the vertical profile of water vapor is controlled by the formation of water ice clouds, it suggests that HCl is taken up by water ice clouds. Finally, we observe that HCl is rapidly disappearing at the end of the southern summer on Mars. We demonstrate that this fast destruction cannot be explained by the standard photochemistry, which suggests that another (unknown) process plays a key role. Increase of hydrogen chloride (HCl) during the southern summer is annually repeated. It shows that HCl formation is independent from a global dust stormVertical distributions of HCl are strikingly similar to water vapor. It suggests that uptake by water ice clouds plays an important roleA rapid decrease of HCl at the end of the southern summer suggests the presence of a strong sink in addition to the photochemical loss Increase of hydrogen chloride (HCl) during the southern summer is annually repeated. It shows that HCl formation is independent from a global dust storm Vertical distributions of HCl are strikingly similar to water vapor. It suggests that uptake by water ice clouds plays an important role A rapid decrease of HCl at the end of the southern summer suggests the presence of a strong sink in addition to the photochemical loss

Ozone (O3) in the atmosphere of Mars is produced following the photolysis of CO2and is readily destroyed by the hydrogen radicals (HOx) released by the photolysis and oxidation of water vapor. As a result, an anti‐correlation between ozone and water vapor is expected. We describe here the O3‐H2O relationship derived from 4 Martian years of simultaneous observations by the SPICAM spectrometer onboard the Mars Express spacecraft. A distinct anti‐correlation is found at high latitudes, where the O3column varies roughly with the −0.6 power of the H2O column. The O3and H2O columns are uncorrelated at low latitudes. To evaluate our quantitative understanding of the Martian photochemistry, the observed O3‐H2O relationship is then compared to that predicted by a global climate model with photochemistry. For identical model and observed abundances of H2O, the model underpredicts observed ozone by about a factor of 2 relative to SPICAM when using the currently recommended gas‐phase chemistry. Sensitivity studies employing low‐temperature CO2absorption cross sections, or adjusted kinetics rates, do not solve this bias. Taking into account potential heterogeneous processes of HOxloss on clouds leads to a significant improvement, but only at high northern latitudes. More broadly, the modeled ozone deficits suggest that the HOx‐catalyzed photochemistry is too efficient in our simulations. This problem is consistent with the long‐standing underestimation of CO in Mars photochemical models, and may be related to similar difficulties in modeling O3and HOxin the Earth's upper stratosphere and mesosphere. The thin ozone layer on Mars is produced when the solar ultraviolet light breaks the CO2molecules that compose 95% of its atmosphere. Conversely, ozone on Mars is readily destroyed by the hydrogen species released by water vapor. An inverse relationship is therefore expected between the quantities of ozone and water vapor. Quantifying this relationship provides important insight into the hydrogen chemistry that stabilizes the composition of the Mars atmosphere. We describe here the ozone and water vapor measurements performed during 4 Martian years (7.5 Earth years) by the SPICAM instrument onboard the Mars Express spacecraft. We then attempt to reproduce these measurements with a Mars climate model with photochemistry. Although the model reproduces the inverse relationship observed between ozone and water vapor, the ozone amount is underestimated by about a factor of 2 in the simulations. The ozone deficit suggests that the destruction by hydrogen species is too strong when one uses the currently recommended reaction rates. This problem is consistent with the long‐standing underestimation in Mars models of carbon monoxide, also destroyed by hydrogen species, and can be related to similar difficulties in modeling ozone in the Earth's upper atmosphere. The relationship between the O3and H2O columns on Mars is quantified from 4 Martian years of simultaneous measurementsThe O3and H2O columns are distinctly anti‐correlated at high latitudes but are uncorrelated at low latitudesModel simulations using the observed amount of H2O and the currently recommended kinetics underpredict O3by about a factor of 2 The relationship between the O3and H2O columns on Mars is quantified from 4 Martian years of simultaneous measurements The O3and H2O columns are distinctly anti‐correlated at high latitudes but are uncorrelated at low latitudes Model simulations using the observed amount of H2O and the currently recommended kinetics underpredict O3by about a factor of 2

The nighttime ozone and sulfur dioxide distributions were analyzed using the entire Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Venus (SPICAV) UV/Venus Express stellar occultation data set. After the discovery of an ozone layer at 100 km in the mesosphere reported by Montmessin, Bertaux, et al. (2011, https://doi.org/10.1016/j.icarus.2011.08.010), 132 other detections were made during the entire 8 years long observing period of the SPICAV UV instrument. In the rare detections, the peak abundances of O3accumulating in the mesosphere are observed with densities from 107to 108molecules⋅cm−3at 85–110 km. The ozone layer is estimated to vary from 1 to 30 ppbv at 85–95 km while at 95–105 km the volume mixing ratio is expected within an interval from 6 to 120 ppbv. Below 93 km, a puzzling decrease of mixing ratio is observed towards midnight at 30°N. Our work also provides an improved sequel to the analysis of the sulfur dioxide survey previously made in the upper mesosphere by Belyaev, Evdokimova, et al. (2017, https://doi.org/10.1016/j.icarus.2017.05.002). On average, the SO2content is found to remain constant throughout the vertical profile at a value of around 135 ± 21 ppbv between 85 and 100 km. Rapid and large variations prevent to conclude firmly on any time or space pattern of SO2. Observations of light attenuation while bright ultraviolet stars were rising or setting behind Venus permitted us to characterize the quantity of carbon dioxide (the main atmospheric component), sulfur oxide, and ozone between 85 and 110 km of altitude at night. They were performed by the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Venus (SPICAV) UV instrument on board the ESA Venus Express mission in 2006–2014. For the first time, this data set has been entirely analyzed with the benefit of recent calibration's improvements enabled more faithful restitution of gases’ abundances. For ozone, discovered on Venus in 2011, thanks to SPICAV, we have been able to detect maximum concentrations and to estimate its nightside characterization. At midlatitudes, a ratio between ozone and carbon dioxide densities, or O3mixing ratio, decreases below 93 km at midnight. This puzzling result is tentatively explained by chemical compounds transported by winds from the dayside hemisphere to the nightside and which are known to quickly react with ozone and destroy it. Sulfur dioxide has been found to vary considerably on a short time scale (days) but, on average, the SO2mixing ratio is constant within 85–100 km. Ozone density is within 107to 108cm−3in the 85–110 km altitude range from 2006 to 2015The altitude profile of the sulfur dioxide volume mixing ratio is vertically uniform around 135 ppbv between 85 and 100 kmTemporal variations of ozone and sulfur dioxide are analyzed Ozone density is within 107to 108cm−3in the 85–110 km altitude range from 2006 to 2015 The altitude profile of the sulfur dioxide volume mixing ratio is vertically uniform around 135 ppbv between 85 and 100 km Temporal variations of ozone and sulfur dioxide are analyzed

We report results from a study of two consecutive Martian years of imaging observations of nitric oxide ultraviolet nightglow by the Imaging Ultraviolet Spectrograph (IUVS) on the Mars Atmosphere and Volatile Evolution (MAVEN) mission spacecraft. The emission arises from recombination of N and O atoms in Mars' nightside mesosphere. The brightness traces the reaction rate as opposed to the abundance of constituents, revealing where circulation patterns concentrate N and O and enhance recombination. Emissions are brightest around the winter poles, with equatorial regions brightening around the equinoxes. These changes offer clear evidence of circulation patterns transitioning from a single cross‐equatorial cell operating during solstice periods to more symmetric equator‐to‐poles circulation around the equinoxes. Prominent atmospheric tides intensify the emissions at different longitudes, latitude ranges, and seasons. We find a strong eastward‐propagating diurnal tide (DE2) near the equator during the equinoxes, with a remarkably bright spot narrowly confined near (0°, 0°). Wave features at the opposite winter poles are dissimilar, reflecting different circulation patterns at perihelion versus aphelion. LMD‐MGCM simulations agree with the patterns of most observed phenomena, confirming that the model captures the dominant physical processes. At the south winter pole, however, the model fails to match a strong wave‐1 spiral feature. Observed brightnesses exceed model predictions by a factor of 1.9 globally, probably due to an underestimation of the dayside production of N and O atoms. Further study of discrepancies between the model and observations offers opportunities to improve our understanding of chemical and transport processes controlling the emission. The MAVEN spacecraft orbiting Mars has obtained a new type of imaging data which reveals the effects of global‐scale winds and waves in the upper atmosphere. Ultraviolet emissions confirm the expected change of wind patterns with season and pinpoint an unusually bright spot on Mars' nightside. Computer model runs successfully match many of the observed features and allow an examination of the underlying physical causes. Differences between the model and observations offer insights on how to improve the model. The MAVEN spacecraft orbiting Mars has obtained a new type of nightside imaging data which reveals the effects of global‐scale winds and waves in the upper atmosphereUltraviolet nightglow emissions confirm the expected change of circulation patterns with season and pinpoint an unusually bright spot on Mars' nightsideA Mars general circulation model successfully matches many of the observed features and allows an examination of the underlying physical causes

Surfur-bearing molecules have been found at the surface of Mars by the Viking lander, the Spirit and Opportunity rovers, and the OMEGA infrared spectrometer aboard Mars Express. However, no gaseous sulfur-bearing species have ever been detected in the Martian atmosphere. We search for SO2signatures in the thermal spectrum of Mars at 7.4 μm using the Texas Echelon Cross Echelle Spectrograph (TEXES) at the NASA Infrared Telescope Facility (IRTF). Data were obtained on Oct. 12, 2009 (Ls = 353°), in the 1350–1360 cm-1range, with a spatial resolution of 1 arcsec (after convolution over three pixels along the N-S axis and two steps along the E-W axis) and a resolving power of 80 000. To improve the signal-to-noise ratio (S/N), we co-added the Martian spectrum around the positions of nine selected SO2transitions with a high S/N and no telluric contamination. From a mean spectrum, averaged over 35 pixels in the region of maximum continuum, we infer a 2σupper limit of 0.3 ppb to the SO2mixing ratio, assuming that our instrumental errors are combined according to Gaussian statistics. Our upper limit is three times lower than the upper limit derived by Krasnopolsky (2005, Icarus, 178, 487), who used the same technique on previous TEXES data. In addition, we derive an upper limit of 2 ppb at each spatial pixel of the region observed by TEXES, which covers the longitude ranges 50 E–170 E for latitudes above 30 N, 100 E–170 E for latitudes between 0 and 30 N, and 110 E–170 E for latitudes between 15 S and 0. The non-detection of localized SO2sources in the observed area is consistent with a homogeneous distribution being expected around equinox for non-condensible species with a lifetime longer than the global mixing time. In view of the typically large SO2/CH4ratio observed in terrestrial volcanoes, and assuming a comparable volcanic composition for Mars and the Earth, our result reaffirms that a volcanic origin is unlikely for any methane in the Martian atmosphere.

Ground-based spatial mapping of Mars provides a unique way to retrieve the global distribution of minor atmospheric species and to study transient phenomena or possible variations with the local hour. We have obtained an instantaneous map of water vapor on Mars near summer solstice (Ls = 80°) using the Texas Echelon Cross Echelle Spectrograph (TEXES) at the NASA Infrared Telescope Facility (IRTF) at Mauna Kea Observatory. Data have been obtained in the 1230–1245 cm-1range (λ= 8.1 μm), with a spatial resolution of 1.1 arcsec (after convolution) and a spectral resolution of 0.012 cm-1(R= 105). The map has been retrieved from the line depth of a weak HDO transition, compared with the line depth of a weak CO2nearby transition. The TEXES map exhibits a strong maximum around the northern pole, as expected from previous observations and from climate model predictions. More interestingly, it shows longitudinal variations, both at high northern latitudes and at mid-latitudes, in close agreement with the predictions of the Global Climate Model developed at the Laboratoire de Meteorologie Dynamique (LMD GCM). The inferred water vapor mixing ratio is also in good agreement with the model predictions. The longitudinal variations at mid latitudes show a general enhancement toward the east. They do not seem to be due to the effect of local hour, but can be explained by dynamical effects generated by the topography. The map of surface temperatures, inferred from the continuum flux, is surprisingly different from the map expected from the climate models; the source of this discrepancy is still unclear.