Martian Climate Database Documentation

What Climate and Meteorology are there on Mars?

Just like on the Earth, there are winds and clouds on Mars...but also CO2 snow, dust storms and other exotic meteorological events!
Mars' atmosphere is a complete and complex system, governed by specific physical, dynamical and chemical processes, which can be observed and understood.
The diurnal and seasonal cycles, combined to extreme and diversified topography, make the red planet's climate quite variable in space and time.
These variations can be modelled and predicted, and this is what the Mars Climate Database is about.
Mars Global Surveyor MOC wide angle camera mozaic displaying water ice clouds, from JPL.

What is the Mars Climate Database?

The Mars Climate Database (MCD) aims at providing scientists, engineers and enthusiasts with a realistic and reliable modelisation of the martian climatological system.
The 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 GCM is developed at Laboratoire de Météorologie Dynamique du CNRS (Paris, France) in collaboration with 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 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.
Water ice column, extracted from the Mars Climate Database.

How to cite the Mars Climate Database ? ^{(click to expand/fold section)}

For general use of the MCD, please cite Forget et al. 1999 and Millour et al. 2018 .
For specific use of variables regarding:

• Dust cycle: please cite Madeleine et al. 2012
• Water cycle: please cite Navarro et al. 2014
• CO2 cycle: please cite Forget et al. 1998
• Planetary Boundary Layer: please cite Colaitis et al. 2013
• Ozone: please cite Lefèvre et al. 2008
• Upper atmosphere: please cite Gonzalez-Galindo et al. 2015
• Electron content in the Ionosphere: please cite Gonzalez-Galindo et al. 2013
• Argon, Nitrogen, and other non-condensable species: please cite Forget et al. 2008

What are the Dust and Solar Extreme UV scenarios? ^{(click to expand/fold section)}

Combinations of dust and solar scenarios have been used because these are the two forcings that are highly variable from year to year.

• On one hand, the solar conditions describe variations in the Extreme UV input which control the heating of the atmosphere above 120 km, which typically varies on a 11 years cycle. Depending on the scenarios, either fixed (i.e. constant over time) solar maximum average and/or minimum conditions are provided, or varying (i.e. changing from day to day, as observed) realistic solar EUV.
• On the other hand, the major factor which governs the variability in the Martian atmosphere is the amount and distribution of suspended dust. Because of this variability, and since even for a given year the details of the dust distribution and optical properties can be uncertain, various model integrations were carried out for the database assuming different "dust scenarios", i.e. prescribing various amount of airborne dust in the simulated atmosphere. 5 dust scenarios are proposed:
  • The Climatology (clim) scenario, which is a simulation ran using the latest version of the LMD Global Climate Model (GCM) forced by a dust distribution reconstructed from observations over Mars Years 24 to 31, and thus representative of a standard (i.e. devoid of a planet-encircling global dust storm). This Climatology scenario is provided with 3 solar EUV conditions: solar min, solar ave, solar max.
  • The cold scenario corresponds to an extremely clear atmosphere ("low dust scenario"; where the dust opacity at a given location is set to be the minimum observed over Mars years 24-31, further decreased by 50%), topped with a solar EUV minimum thermospheric forcing.
  • The warm scenario corresponds to "dusty atmosphere" conditions, but nonetheless non-dust storm conditions (the dust opacity at a given location is set to the maximum observed, unless during a global dust storm, further increased by 50%), topped with a solar maximum thermosphere.
  • The dust storm scenario represents Mars during a global dust storm (dust opacity set to 5 at all times and over the whole planet). Moreover the dust optical properties are for this case set to represent "darker dust" than nominal (in practice for these runs, Ockert-Bell et al. dust properties were used, rather than the more recently derived Wolff et al. ones). This scenario is only provided for when such storms are likely to happen, during northern fall and winter (Ls=180-360), but with 3 cases of solar EUV inputs: solar min, solar ave, solar max.
  • The Mars Years scenarios (MY24, MY25, ..., MY32, MY33) correspond to our best representation of these specific years, both in terms of daily atmospheric dust loading and daily solar EUV input.

How does the MCD interpolate to high resolution topography? ^{(click to expand/fold section)}

The MCD access software includes a "high resolution" mode which combines high resolution (32 pixels/degree) MOLA topography and the smoothed Viking Lander 1 pressure records (used as a reference to correct the atmospheric mass) with the MCD surface pressure in order to compute surface pressure as accurately as possible. The latter is then used to reconstruct vertical pressure levels and hence, within the restrictions of the procedure, yield high resolution values of atmospheric variables. The procedure by which high accuracy surface pressure is computed is also implemented as a light and autonomous tool (see user manual for more detailed explanations).

What's more in the full version of the MCD? ^{(click to expand/fold section)}

The full version of the MCD includes :

• the MCD access software, as a Fortran subroutine so that users can call it from their own programs;
• examples of interfaces to call the MCD from Python, C or C++ programs or IDL, Matlab and Scilab softwares;
• realistic added large scale and small scale perturbation schemes to represent the possible meteorology at a given location and time.

Complete documentation of the MCD ^{(click to expand/fold section)}

Interested readers are encouraged to read the following documents:

• The Mars Climate Database v6.1 user's manual, which is included in the distributed database.
• The Mars Climate Database v6.1 detailed design document, which presents the technical details on the Mars Climate Database post-processing software design and implementation.
• The Mars Climate Database v6.1 validation document, which presents comparisons between available data and outputs from the Mars Climate Database.

How does the LMD Global Climate Model (GCM) work? ^{(click to expand/fold section)}

A General Circulation Model (GCM) is a numerical model that computes the temporal evolution of the atmosphere of a planet. It solves well known equations of motion and thermodynamics on a 3D grid that covers the entire atmosphere.
The LMD Mars GCM accounts for the specific physical processes at work on Mars, from the surface to the exobase such as the condensation of the CO2 atmosphere during polar nights, the generation and evolution of water ice clouds, the distribution of airborne dust, the many chemical reactions that take place, etc.