34 research outputs found
Explanation for the increase in high altitude water on Mars observed by NOMAD during the 2018 global dust storm
The Nadir and Occultation for MArs Discovery (NOMAD) instrument on board ExoMars Trace Gas Orbiter (TGO) measured a large increase in water vapor at altitudes in the range of 40â100 km during the 2018 global dust storm on Mars. Using a threeâdimensional general circulation model, we examine the mechanism responsible for the enhancement of water vapor in the upper atmosphere. Experiments with different prescribed vertical profiles of dust show that when more dust is present higher in the atmosphere the temperature increases and the amount of water ascending over the tropics is not limited by saturation until reaching heights of 70â100 km. The warmer temperatures allow more water to ascend to the mesosphere. Photochemical simulations show a strong increase in highâaltitude atomic hydrogen following the highâaltitude water vapor increase by a few days
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Carbon dioxide retrievals from NOMADâSO on ESAâs ExoMars Trace Gas Orbiter and temperature profiles retrievals with the hydrostatic equilibrium equation: 2. Temperature variabilities in the mesosphere at Mars terminator.
The Solar Occultation (SO) channel of the Nadir and Occultation for Mars Discovery (NOMAD) instrument scans the Martian atmosphere since 21 April 2018. In this work, we present a subset of the NOMAD SO data measured at the mesosphere. We focused on a spectral range that started to be recorded in Martian year (MY) 35. A total of 968 vertical profiles of carbon dioxide density and temperature covering MY 35 and the beginning of MY 36 were investigated until 135° of solar longitude. We compared 47 profiles with co-located profiles of the Mars Climate Sounder onboard the Mars Reconnaissance Orbiter. Most profiles show a good agreement as SO temperatures are only 1.8 K higher, but some biases lead to an average absolute difference of 7.4°K. The SO data set is also compared with simulations from the Global Environmental Multiscale-Mars general circulation model. Both data sets are in good agreement except for the presence of a cold layer in the winter hemisphere and a warm layer at dawn in the Northern hemisphere for solar longitudes between 240° and 360°. Five profiles contain temperatures lower than the limit for CO2 condensation. Strong warm layers were found in 13.5% of the profiles. They are present mainly at dawn and in the winter hemisphere, while the Northern dusks appear featureless. The data set mainly covers high latitudes around 60° and we derived some non-migrating tides. In the Southern winter hemisphere, we derived apparent zonal wavenumber-1 (WN-1) and WN-3 tidal components with a maximum amplitude of 10% and 5% at 63 km, respectively
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Water Vapor Vertical Profiles on Mars in Dust Storms Observed by TGO/NOMAD
It has been suggested that dust storms efficiently transport water vapor from the nearâsurface to the middle atmosphere on Mars. Knowledge of the water vapor vertical profile during dust storms is important to understand water escape. During Martian Year 34, two dust storms occurred on Mars: a global dust storm (June to midâSeptember 2018) and a regional storm (January 2019). Here we present water vapor vertical profiles in the periods of the two dust storms (Ls = 162â260° and Ls = 298â345°) from the solar occultation measurements by Nadir and Occultation for Mars Discovery (NOMAD) onboard ExoMars Trace Gas Orbiter (TGO). We show a significant increase of water vapor abundance in the middle atmosphere (40â100 km) during the global dust storm. The water enhancement rapidly occurs following the onset of the storm (Ls~190°) and has a peak at the most active period (Ls~200°). Water vapor reaches very high altitudes (up to 100 km) with a volume mixing ratio of ~50 ppm. The water vapor abundance in the middle atmosphere shows high values consistently at 60°Sâ60°N at the growth phase of the dust storm (Ls = 195°â220°), and peaks at latitudes greater than 60°S at the decay phase (Ls = 220°â260°). This is explained by the seasonal change of meridional circulation: from equinoctial Hadley circulation (two cells) to the solstitial one (a single poleâtoâpole cell). We also find a conspicuous increase of water vapor density in the middle atmosphere at the period of the regional dust storm (Ls = 322â327°), in particular at latitudes greater than 60°S
Lixiviação do picloram em argissolo vermelho-amarelo e latossolo vermelho-amarelo com diferentes valores de pH
Relationships between structure of the tree component and environmental variables in a subtropical seasonal forest in the upper Uruguay River valley, Brazil
Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries
Background
Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres.
Methods
This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and lowâmiddle-income countries.
Results
In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of âsingle-useâ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for lowâmiddle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia.
Conclusion
This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both highâ and lowâmiddleâincome countries
Impact of gradients at the Martian terminator on the retrieval of ozone from SPICAM/MEx
International audienc
Impact of gradients at the Martian terminator on the retrieval of ozone from SPICAM/MEx
International audienc
Optical and radiometric models of the NOMAD instrument part II: the infrared channels - SO and LNO
NOMAD is a suite of three spectrometers that will be launched in 2016 as part of the joint ESA-Roscosmos ExoMars Trace Gas Orbiter mission. The instrument contains three channels that cover the IR and UV spectral ranges and can perform solar occultation, nadir and limb observations, to detect and map a wide variety of Martian atmospheric gases and trace species. Part I of this work described the models of the UVIS channel; in this second part, we present the optical models representing the two IR channels, SO (Solar Occultation) and LNO (Limb, Nadir and Occultation), and use them to determine signal to noise ratios (SNRs) for many expected observational cases. In solar occultation mode, both the SO and LNO channel exhibit very high SNRs >5000. SNRs of around 100 were found for the LNO channel in nadir mode, depending on the atmospheric conditions, Martian surface properties, and observation geometry