Mars General Circulation Model (GCM) and data assimilation

We have developed a Mars GCM in collaboration with scientists at the Laboratoire de Météorologie Dynamique of the Ecole Normale Supèrieure in Paris and Université de Paris VI, and at the Instituto de Astrofisica de Andalucia in Spain. This is being used to study the meteorology and climate of Mars, and to produce a Mars Climate Database with the support of the European Space Agency. The model is able to simulate realistic weather conditions, including atmospheric dust conditions and the planet's water cycle, as well as long term climate evolution.

Current projects:

Dust lifting and dust storm initiation in the Martian atmosphere (David Mulholland)

Atmospheric dust represents a major component of the Martian climate system, with a radiative forcing that can dramatically alter the global mean circulation and temperature structure. The initiation of dust storms appears to be a somewhat random process, and is not well understood at present. We use the UK Mars GCM to investigate the mechanisms and locations of storm initiation, and the effects of feedbacks with the surface and interactions with the water/ice cycle. Accurate prediction of the occurrence of dust lifting events is of particular importance with regard to lander/rover missions to Mars.

HST images of Mars from 2001 showing the huge increase in atmospheric dust loading that occurs during a global storm.

A planet-encircling dust storm beginning on the rim of the Hellas basin simulated by the Mars GCM

The movie above shows a simulated planet-encircling dust storm beginning on the rim of the Hellas basin, close to where several storms have been observed. The basin can be seen in the shading on the surface, which denotes the topography. The 3D colours are dust mass mixing ratio in kg/kg. Each timestep is a quarter of a sol (day) so the video spans 15 sols, showing the rapid formation of the storm. The axes are lat/lon in degrees and pseudo-height in km.

Mars data assimilation (Luca Montabone and Tao Ruan)

On Earth, data assimilation is used in routine operational weather forecasting, primarily to produce accurate initial conditions for the forecasts. We have applied a similar technique to another planet in the Solar System: Mars.

Observations of atmospheric temperature and dust opacity from the Thermal Emission Spectrometer on board NASA's Mars Global Surveyor spacecraft have been assimilated for three complete Martian years into the UK Mars Global Circulation Model. This four-dimensional 'reanalysis' allows us to study the evolution of the atmospheric state on a model grid while remaining consistent with the observations, the model, and our physical understanding. It also allows us to access variables that cannot be directly observed, such as winds and surface pressure, as the model balances the unobserved variables against the observed variables as the assimilation progresses.

Assimilated transient surface pressure in Mars' southern hemisphere during Mars year 25, just before the onset of the planet-encircling dust storm.

Mars Analysis Correction Data Assimilation (MACDA)

This dataset contains the three years of assimilated data, and is available here via the British Atmospheric Data Centre's website.

Currently we are extending the reanalysis to two further Martian years, using observations from the Mars Climate Sounder instrument on board NASA's Mars Reconnaissance Orbiter.