Europlanet Science Congress 2022
Palacio de Congresos de Granada, Spain
18 – 23 September 2022
Europlanet Science Congress 2022
Palacio de Congresos de Granada, Spain
18 September – 23 September 2022

TP7

Atmospheres and Exospheres of Terrestrial Bodies

Space missions have provided a wealth of data on the atmospheres and aeronomy of rocky planets and moons, from the lower layers up to the external envelopes in direct contact with the solar wind. A recent emerging finding is evidence that the atmosphere behaves as a single coherent system with complex coupling between layers.

This session solicits contributions that investigate processes at work (chemistry, energetics, dynamics, electricity, escape etc...) on the terrestrial bodies of the Solar System and includes studies of the coupling between the lower/middle and upper atmospheres. Contributions based on analysis of recent spacecraft and ground-based observations, comparative planetology studies, numerical modelling and relevant laboratory investigations are particularly welcome. We encourage colleagues from Tianwen-1 (China) and Hope (UAE) missions to submit abstracts that would help strengthen collaboration with the broader planetary atmospheres community. In view of the three future Venus missions selected by ESA and NASA, papers discussing contemporary Venus atmospheric science in preparation for these missions are also encouraged.
The session will consist of invited and contributed oral talks as well as posters.

Convener: Anni Määttänen | Co-conveners: Francisco González-Galindo, Dmitrij Titov
Orals
| Thu, 22 Sep, 10:00–13:30 (CEST)|Room Machado
Posters
| Attendance Thu, 22 Sep, 18:45–20:15 (CEST)|Poster area Level 1

Orals: Thu, 22 Sep | Room Machado

Mars
10:00–10:10
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EPSC2022-786
Ehouarn Millour, Francois Forget, Aymeric Spiga, Thomas Pierron, Antoine Bierjon, Luca Montabone, Margaux Vals, Franck Lefèvre, Jean-Yves Chaufray, Miguel Lopez-Valverde, Francisco Gonzalez-Galindo, Stephen Lewis, Peter Read, Marie-Christine Desjean, and Fabrice Cipriani and the MCD Team

Introduction:

The Mars Climate Database (MCD) is a database of meteorological fields derived from General Circulation Model (GCM) numerical simulations of the Martian atmosphere and validated using available observational data. The MCD includes complementary post-processing schemes such as high spatial resolution interpolation of environmental data and means of reconstructing the variability thereof.

The GCM that is used to create the MCD data, now known as the Mars Planetary Climate Model (Mars PCM) is developed at Laboratoire de Météorologie Dynamique du CNRS (Paris, France) [1] in collaboration with LATMOS (Paris, France), the Open University (UK), the Oxford University (UK) and the Instituto de Astrofisica de Andalucia (Spain) with support from the European Space Agency (ESA) and the Centre National d'Etudes Spatiales (CNES).

The latest version of the MCD, version 5.3 [2], was released in July 2017, and at the time of writing of this abstract we are working on MCDv6.1 [3], which we will release in June 2022. This new version will benefit from all the recent developments and improvements in the Mars PCM’s physics package.

The MCD is freely distributed and intended to be useful and used in the framework of engineering applications as well as in the context of scientific studies which require accurate knowledge of the state of the Martian atmosphere. Over the years, various versions of the MCD have been released and handed to more than 400 teams around the world.

Current applications include entry descent and landing (EDL) studies for future missions, investigations of some specific Martian issues (via coupling of the MCD with homemade codes), analysis of observations (Earth-based as well as with various instruments onboard Mars Express, Mars Reconnaissance Orbiter, Maven, Trace Gas Orbiter, Hope),...

The MCD is freely available upon request via an online form on the dedicated website: http://www-mars.lmd.jussieu.fr which moreover includes a convenient web interface for quick looks.

Figure 1: Illustrative example of the online Mars Climate Database web interface and its plotting capabilities.

Overview of MCD contents:

The MCD provides mean values and statistics of the main meteorological variables (atmospheric temperature, density, pressure and winds) as well as atmospheric composition (including dust and water vapor and ice content), as the GCM from which the datasets are obtained includes water cycle, chemistry, and ionosphere models. The database extends up to and including the thermosphere (~350km). Since the influence of Extreme Ultra Violet (EUV) input from the sun is significant in the latter, 3 EUV scenarios (solar minimum, average and maximum inputs) account for the impact of the various states of the solar cycle.

As the main driver of the Martian climate is the dust loading of the atmosphere, the MCD provides climatologies over a series of synthetic dust scenarios: standard year (a.k.a. climatology), cold (i.e: low dust), warm (i.e: dusty atmosphere) and dust storm, These are derived from home-made, instrument-derived (TES, THEMIS, MCS, MERs), dust climatology of the last 12 Martian years. In addition, we also provide additional “add-on” scenarios which focus on individual Martian Years (from MY 24 to MY 35) for users more interested in more specific climatologies than the MCD baseline scenarios.

In practice the MCD provides users with:

  • Mean values and statistics of main meteorological variables (atmospheric temperature, density, pressure and winds), as well as surface pressure and temperature, CO2 ice cover, thermal and solar radiative fluxes, dust column opacity and mixing ratio, [H20] vapor and ice concentrations, along with concentrations of many species: [CO], [O2], [O], [N2], [Ar], [H2], [O3], [H] ..., as well as electrons mixing ratios. Column densities of these species are also given.

  • Physical processes in the Planetary Boundary Layer (PBL), such as PBL height, minimum and maximum vertical convective winds in the PBL, surface wind stress and sensible heat flux.
  • The possibility to reconstruct realistic conditions by combining the provided climatology with additional large scale (derived from Empirical Orthogonal Functions extracted from the GCM runs) and small scale perturbations (gravity waves).

  • Dust mass mixing ratio, along with estimated dust effective radius and dust deposition rate on the surface are provided.

  • A high resolution mode which combines high resolution (32 pixel/degree) MOLA topography records and Insight pressure records with raw lower resolution GCM results to yield, within the restriction of the procedure, high resolution values of atmospheric variables (pressure, but also temperature and winds via dedicated schemes).

 

Validation of MCDv6.1:

At EPSC2022 we will present validation campaigns between the MCDv6.1 and multiple measurements such as:

  • Surface temperatures, atmospheric temperatures and water vapor from TES/MGS.

  • Atmospheric temperatures, water ice and airborne dust from MCS/MRO.

  • Atmospheric temperatures from MGS and MEx radio occultations

  • Atmospheric temperatures from TIRVIM/ACS/TGO

  • Surface pressures recorded by Viking Landers, Phoenix, Curiosity and Insight

  • And hopefully much more...

 

References:

[1] Forget et al. (2022), “Challenges in Mars Climate Modelling with the LMD Mars Global Climate Model, Now Called the Mars « Planetary Climate Model »(PCM) “, The 7th International Workshop on the Mars Atmosphere : Modelling and Observations, 14-17 June 2022, Paris, France.

[2] Millour et al. (2018), “The Mars Climate Database (version 5.3) “, From Mars Express to ExoMars Scienfic Workshop, 22-28 February 2018, ESAC Madrid, Spain.

[3] Millour et al. (2022), “The Mars Climate Database, Version 6.1 “, The 7th International Workshop on the Mars Atmosphere : Modelling and Observations, 14-17 June 2022, Paris, France.

How to cite: Millour, E., Forget, F., Spiga, A., Pierron, T., Bierjon, A., Montabone, L., Vals, M., Lefèvre, F., Chaufray, J.-Y., Lopez-Valverde, M., Gonzalez-Galindo, F., Lewis, S., Read, P., Desjean, M.-C., and Cipriani, F. and the MCD Team: The Mars Climate Database (Version 6.1), Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-786, 2022.

10:10–10:20
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EPSC2022-260
Jean-Claude Gérard, Lauriane Soret, Rena Lee, Joe Ajello, J. Scott Evans, Nicholas Schneider, and Sonal Jain

The spin-forbidden CO a 3Π→ X 1Σ Cameron bands (190-270 nm) are the dominant feature of the middle ultraviolet spectrum of the Martian dayglow and aurora. Since their discovery in the Mars dayglow during the Mariner era (Barth, 1969), a number of studies based on observations with the SPICAM instrument on board the Mars Express (Leblanc et al., 2006; Cox et al., 2010; González‐Galindo et al., 2018) and IUVS/MAVEN (Jain et al., 2015) have revealed their altitude distribution and seasonal changes (Gérard et al., 2019). The Cameron bands are also an important marker of the distribution of auroral events on the nightside aurora, together with the CO2+ ultraviolet doublet at 288-289 nm (Gérard et al., 2015; Schneider et al., 2015). One of the important processes producing the metastable a 3Π upper state of the transition is dissociative excitation of CO2 by impact of photoelectrons or auroral electrons:

 e (E> 11.5 eV) + CO2 à CO (a 3Π) + O + e

 The excitation process includes cascades from higher lying states, which makes ab initio calculations quite complex.

Until recently, models for the production of the Cameron bands used the energy dependence of the cross section initially published by Ajello (1971) 50 years ago. It was later normalized by Avakyan et al. (1999) to the value of Erdman and Zipf (1983) at 80 eV. The absolute value of the cross section was later scaled by different factors to account for revisions of the radiative lifetime of the a3Π state and match the observations.  Recently, a new set of measurements in a large laboratory facility attenuating the wall effects has led to a revision of both the shape and the peak value of this cross section (Lee et al., 2021a).

In this presentation, we assess the consequences of this revision on the production of the Cameron bands in the Martian airglow and aurora. In particular, we discuss the importance of the contribution of the excitation of CO by electron impact e (E> 6 eV) + CO → CO(a 3Π) + e,  also recently re-examined by Lee et al. (2021b).  We discuss the relative importance of the two processes and its dependence on the CO mixing ratio in the Mars thermosphere. We also examine how these new values may affect the anomalies in the Cameron/CO2+ UV doublet intensity ratio observed with IUVS in the discrete aurora (Soret et al., 2021).

References

Ajello, J. M. (1971). The Journal of Chemical Physics55(7), 3169-3177.

Avakyan, S. V. et al. (1999).  CRC Press.

Barth, C. A. et al. (1969). Science165(3897), 1004-1005.

Cox, C. et al. (2010). Journal of Geophysical Research: Planets115(E4).

Erdman, P. W., & Zipf, E. C. (1983). Planetary and Space Science31(3), 317-321.

Gérard, J. C. et al. (2019). Journal of Geophysical Research: Space Physics124(7), 5816-5827.

González‐Galindo, F. et al. (2018). Journal of Geophysical Research: Planets123(7), 1934-1952.

Jain, S. K. et al. (2015). Geophysical Research Letters42(21), 9023-9030.

Leblanc, F. et al. (2006). Journal of Geophysical Research: Planets111(E9).

Lee, R., et al. (2021a). Mars and Venus dayglow studies based upon laboratory aeronomy from electron Impact of CO2 for analysis of UV Observations by MAVEN, EMM, MEx, and VEx. AGU Fall meeting 2021, New Orleans.

Lee, R. A. et al. (2021b). Journal of Geophysical Research: Planets126(1), e2020JE006602.

Schneider, N. M. et al. (2015). Discovery of diffuse aurora on Mars. Science350(6261), aad0313.

Soret, L. et al. (2021). Journal of Geophysical Research: Space Physics126(10), e2021JA029495.

 

How to cite: Gérard, J.-C., Soret, L., Lee, R., Ajello, J., Evans, J. S., Schneider, N., and Jain, S.: The CO Cameron bands in the Mars dayglow and aurora:consequences of revised cross sections, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-260, 2022.

10:20–10:30
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EPSC2022-274
Matteo Crismani, Robert Tyo, Nicholas Schneider, John Plane, Wuhu Feng, Juan-Diego Carrillo-Sanchez, Geronimo Villanueva, Sonal Jain, and Justin Deighan

Since the discovery of atmospheric Mg+ at Mars in 2015 by the Mars Atmosphere and Volatile Evolution (MAVEN) mission, there have been almost continuous observations of this meteoric ion layer in a variety of seasons, local times, and latitudes. Here we present the most comprehensive set of observations of the persistent metal ion layer at Mars, constructing the first grand composite maps of a metallic ion species. These maps demonstrate that Mg+ appears in almost all conditions when illuminated, with peak values varying between 100 and 500 cm-3, dependent on season and local time. There exists significant latitudinal variation within a given season, indicating that Mg+ is not simply an inert tracer, but instead may be influenced by the meteoric input distribution and/or atmospheric dynamics and chemistry. Geographic maps of latitude and longitude indicate that Mg+ may be influenced by atmospheric tides, and there is no apparent correlation with remnant crustal magnetic fields. This work also presents counter-intuitive results, such as a reduction of Mg+ ions in the northern hemisphere during Northern Winter in an apparent correlation with dust aerosols.

How to cite: Crismani, M., Tyo, R., Schneider, N., Plane, J., Feng, W., Carrillo-Sanchez, J.-D., Villanueva, G., Jain, S., and Deighan, J.: Martian Meteoric Mg+: Atmospheric Distribution and Variability from MAVEN/IUVS, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-274, 2022.

10:30–10:40
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EPSC2022-436
Franck Montmessin, Denis Belyaev, Franck Lefevre, Juan Alday, Anna Fedorova, Oleg Korablev, Alexander Trokhimovskiy, Mike Chaffin, and Nick Schneider

We have used a 1D hybrid model to represent the ascent of a wet air parcel at times of intense dust and transport activity. This model combines observations of the ACS instrument that measured, for the first time, water vapor abundance from 20 to 120 km. These observations enable the in-depth study of how the water vapor penetration to high altitude contributes to hydrogen production above 80 km. In contrast with other 1D models that have been used to explore Mars’ photochemistry, our model represents the vertical transport through advection with a constant velocity of 10 cm/s up to 100 km. Our results imply that, contrary to a common assumption made in models used to study Mars’ photochemistry and escape processes, the region between 60 and 80 km cannot be neglected in the production and migration of hydrogen to the upper atmosphere. In particular, these results imply that upper atmosphere photochemistry models intending to capture Southern Summer conditions need to carefully consider the flux boundary condition for H at the lower boundary if it is higher than 80 km. Testing a variety of configurations, from the MY34 GDS to the recent MY35 perihelion period, we have been able to assess how the hydrogen upward flux from above 60 km varies with events. Stochastic events (GDS and A, B, C- storms) have a strong imprint on the escape budget, but our results suggest perihelion remains the dominant escape component on the long term.

How to cite: Montmessin, F., Belyaev, D., Lefevre, F., Alday, J., Fedorova, A., Korablev, O., Trokhimovskiy, A., Chaffin, M., and Schneider, N.: Reappraising the Production and Transfer of Hydrogen to the Upper Atmosphere at Times of Elevated Water Vapor  , Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-436, 2022.

10:40–10:50
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EPSC2022-693
Francisco González-Galindo, Jean-Yves Chaufray, Gabriella Gilli, Margaux Vals, Franck Lefèvre, Franck Montmessin, Loic Rossi, Francois Forget, Ehouarn Millour, Miguel Ángel López-Valverde, and Adrián Brines

Introduction

The thermal (Jeans) escape of Hydrogen accumulated during the history of Mars has been one of the major mechanisms explaining the transition of Mars from a thicker and wetter atmosphere in the past to the current thin and dry atmosphere (Brain et al., 2017). Recent observations (Heavens et al., 2018, Chaffin et al., 2021) have revealed a clear link between the water cycle in the lower atmosphere, the transport of water to the middle/upper atmosphere, and the thermal escape of Hydrogen. However, many unknowns remain, including the role of the different processes responsible of transporting water from the lower to the upper atmosphere and converting it to Hydrogen atoms, or the effects of global dust storms (GDS hereafter) compared to the regular seasonal variability.

While different 1D models have been used to reproduce and understand some of the observations (e.g. Chaffin et al., 2017), until now global models have failed to reproduce the observed variability of the H escape. In particular, a recent study with the Laboratoire de Météorologie Dynamique Mars Global Climate Model (LMD-MGCM hereafter) evidences that the model significantly underestimates the H escape rate when comparing with Mars Express SPICAM observations, in particular during the perihelion season (Chaufray et al., 2021).

In this work we will summarize the recent improvements that we have included in the LMD-MGCM in order to better reproduce the observed Hydrogen escape rate, and will discuss some of the results obtained with the improved model.

Model description

We have included three improvements with respect to the version of the LMD-MGCM used in Chaufray et al., 2021.

First, we have incorporated in the simulations a sophisticated model of the microphysics of water ice clouds allowing for the formation of supersaturated water layers (Navarro et al., 2014). Second, we have extended the photochemical model in the LMD-MGCM to incorporate the chemistry of H2O+ and derived ions, as well as of deuterated (both neutral and ion) species. Third, we have also included in the calculations an improved model of deuterium fractionation (Vals et al., 2022). While this allows us to study the D escape, we will focus here only on the H escape; simulations of the deuterium escape are discussed in Chaufray et al. (this issue).

Preliminary results

The incorporation in the calculations of the microphysical model allowing for the formation of supersaturated water layers significantly increases the amount of water in the upper atmosphere of the planet with respect to the previous calculations, producing a strong enhancement of up to one order of magnitude in the H escape rate. The incorporation of the chemistry of water-derived ions further increases the escape rate in between ~20 and ~40%, depending on the season. This results in a better agreement with observations of H escape (figure 1). However, significant differences still remain. In particular, the decrease in the rate of H escape at the end of the year is not well captured by the model, suggesting that, in the model, water remains in the upper atmosphere longer than observed.

We study also the interannual variability of the simulated escape rate. While the solar activity seems to play a secondary role, dust storms in the lower atmosphere have a clear effect over the H escape rate. Our simulations show, for example, that the global dust storm in MY34 increased the annually integrated H escape rate in about 30%. This confirms the importance of taking into account the effects of GDSs when calculating the accumulated escape rate over Martian history.

This work opens the doors to studying the H escape rate at past Mars conditions characterized by different orbital parameters (e.g. obliquity, time of perihelion, etc.). See Gilli et al., this issue, for a first study in this direction.

Figure 1. H escape rate simulated for MY28 (light green line) and MY33 (orange line). The black thin line shows the escape rate for MY28 simulated with the previous model version, taken from Chaufray et al. (2021). The green and red symbols represent measured values of the H escape rate during MY28 and MY33, respectively, taken from Chaffin et al. (2014) and Heavens et al. (2018)

Acknowledgements

F.G-G. and G.G. are funded by the Spanish Ministerio de Ciencia, Innovación y Universidades, the Agencia Estatal de Investigación and EC FEDER funds under project RTI2018-100920-J-I00. AB and MALV were supported by grant PGC2018-101836-B-100 (MCIU/AEI/FEDER, EU). The IAA team acknowledges financial support from the State Agency for Research of the Spanish MCIU through the Center of Excellence “Severo Ochoa" award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709)

References

Brain, D., et al., (2017), Solar Wind Interaction and Atmospheric Escape. Chapter 15 in “The Atmosphere and Climate of Mars”, Cambridge University Press, doi:10.1017/9781139060172.015

Chaffin, M., et al. (2021), Martian water loss to space enhanced by regional dust storms, Nat. Astron. doi:10.1038/s41550-021-01425-w

Chaufray, J.-Y., et al. (2021), Study of the hydrogen escape rate at Mars during martian years 28 and 29 from comparisons between SPICAM/Mars express observations and GCM-LMD simulations. Icarus, doi:10.1016/j.icarus.2019.113498

Heavens, N., et al. (2018). Hydrogen escape from Mars enhanced by deep convection in dust storms. Nat. Astron., doi:10.1038/s41550-017-0353-4

Navarro, T., et al. (2014), Global climate modeling of the Martian water cycle with improved microphysics andadiatively active water ice clouds. JGR (Planets), doi.org:10.1002/2013JE004550

Vals, M., et al. (2022), Improved modeling of Mars' HDO cycle using a Mars' Global Climate Model. Paper submitted to JGR-Planets.

How to cite: González-Galindo, F., Chaufray, J.-Y., Gilli, G., Vals, M., Lefèvre, F., Montmessin, F., Rossi, L., Forget, F., Millour, E., López-Valverde, M. Á., and Brines, A.: Simulation of the Hydrogen escape from Mars using a Global Climate Model, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-693, 2022.

10:50–11:00
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EPSC2022-696
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ECP
Ashwin Braude, Franck Montmessin, Kevin Olsen, Margaux Vals, Juan Alday, Loïc Rossi, Alexander Trokhimovskiy, Anna Fedorova, Frédéric Schmidt, Oleg Korablev, Franck Lefèvre, Lucio Baggio, Abdanour Irbah, Gaetan Lacombe, Andrey Patrakeev, and Alexey Shakun

Abstract

Measuring vertical variations in the deuterium to hydrogen ratio with altitude is essential in understanding the processes that lead to the escape of water vapour from the Martian atmosphere. We retrieve vertical profiles of HDO and H2O from the ACS instrument, monitoring seasonal changes particularly above the water condensation level. We discuss these results in relation to previously observed seasonal variations in D/H together with the expected variations from theoretical models.

Introduction

The ratio of deuterium to hydrogen (D/H) is a sensitive tracer of the rate of escape of water from the Martian atmosphere over its history. Hydrogen preferentially escapes from the atmosphere over its heavier isotope (e.g. [1]), and so the greater the amount of historical escape of water vapour, the larger the average D/H ratio. On Mars, this value is measured to be around 4-6 times that of terrestrial distilled ocean water [2,3], showing that the early atmosphere of Mars contained significantly more water than it does today. In addition, a number of processes in the lower and middle atmosphere can cause relative changes in the concentrations of semi-heavy water (HDO) with respect to water vapour, notably due to differences in rates of cloud deposition (e.g. [4,5]) and photolysis (e.g. [6,7]). We therefore wish to look at spatial and temporal changes in the vertical profile of D/H, particularly above the level of water condensation, in order to better characterise the processes that influence the escape of water vapour from the lower atmosphere into space.

Method

The mid-infrared channel of the Atmospheric Chemistry Suite Instrument (ACS MIR, [8]) on board the ExoMars Trace Gas Orbiter obtains transmission spectra of the Martian atmosphere in solar occultation geometry, which is sensitive to trace gases at very low abundance and at high vertical resolution. We make use of observations in grating position 11, which is sensitive to a wavenumber regime in which a large number of resolvable HDO lines are present that in the best cases provide sensitivity to HDO abundance up to around 70 km. These are then inverted using the RISOTTO radiative transfer and retrieval pipeline [9,10] to give vertical profiles of HDO volume mixing ratio. Concurrent vertical profiles of H2O are obtained using the near-infrared (NIR) channel of the same instrument [11], and then the D/H ratio computed assuming that H2O and HDO are the main carriers of the two isotopes of hydrogen. Accurate quality control of the data is performed using probability-sparse Non-negative Matrix Factorisation (psNMF [12,13]).

Results and Perspective

We report seasonal changes in the fractionation of D/H in the middle atmosphere throughout the temporal range of the data starting from the autumn equinox in MY34 to the end of MY 35. These will be discussed in relation to the findings of seasonal changes in the vertical profiles of D/H reported by the NOMAD instrument [14], and the results interpreted in relation to predictions from Global Climate Models (GCMs) of HDO ([5,15,16]).