Assimilating Martian atmospheric constituents using a gobal circulation model

Copyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyright owners. For more information on Open Research Online's data policy on reuse of materials please consult the policies page. Introduction: The technique of data assimilation is employed in a novel way for a planetary atmosphere to perform a complete spatial and temporal analysis of martian atmospheric constituent data over periods of several Mars years. Observations of martian atmospheric constituents, generally made from orbiting spacecraft, are often sparse and incomplete. A global circulation model can be used to predict the transport, phase changes and chemical reactions that these species undergo. If constrained by observations, it can then provide a consistent interpolation to unobserved regions and, in principle, a useful a priori for future retrievals. Furthermore, any consistent misfit between the model predictions and new observations can be used to identify potentially important physical processes that are missing from the model, including inferring the presence and location of sources and sinks. The scientific impact possible by applying data assimilation techniques to retrieved observations including those of water vapour, water ice and ozone will be demonstrated, as well as some of the constraints on the data sets required to make the process useful. Data Assimilation: Data assimilation, the combination of observations and numerical models which provide physical constraints, and organize and propagate the observational information that is introduced, is commonly used as a means of analysing large atmospheric and oceanic observational data sets for the Earth [1] and notably to form initial states for numerical weather forecasts [2]. Data assimilation also offers significant potential advantages for the analysis of atmospheric data from other planets, which have been demonstrated by the successful assimilation of thermal and dust opacity data over a period of up to eight martian years (about fifteen Earth years). This includes thermal and dust opacity observations from the Thermal Emission Spectrometer (TES) aboard NASA Mars Global Surveyor [3,4] and Mars Climate Sounder (MCS) observations from NASA Mars Reconnaissance Orbiter (MRO). While previous work, with both the present [3] and other data assimilation schemes [5], has largely focussed on assimilation of temperature and total column dust opacity in order to constrain the atmospheric circulation , we have now implemented an extension to the procedure to include three-dimensional dust transport, water cloud aerosol and chemical species. This will enhance our understanding of the dynamics …