37th DPS Meeting, 4-9 September 2005
Session 33 Mars' Atmosphere
Poster, Tuesday, September 6, 2005, 6:00-7:15pm, Music Recital Room

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[33.18] Perihelion season mesoscale circulations in the Hellas: simulations based on MGS/TES assimilated data

T. Siili, S. Järvenoja (Finnish Meteorological Institute), J. Kauhanen (University of Helsinki), S. R. Lewis, L. Montabone (Oxford University), M. Parviainen (Finnish Meteorological Institute), P. L. Read (Oxford University), H. Savijärvi (University of Helsinki)

The Mars Limited Area Model (MLAM) is a spatially fully 3-D Mars Mesoscale Circulation Model and is based on the dynamical core of the widely (primarily in Europe) used operational weather forecast model HIRLAM (HIgh Resolution Limited Area Model), v.\ 5.0.0. For MLAM the planetary constants and parameterisations (the ``physics'') appropriate for Mars have replaced the terrestrial values and schemes of the HIRLAM. The MLAM reference version is ``dry'', i.e., it does not include water vapour processes; dust transport capabilities are also not included yet.

A limited area model needs also realistic initial and boundary conditions; in the early test phase they were taken from the European Mars Climate Database. Our current MLAM reference version utilises primarily simulation results of the Oxford University's Mars General Circulation Model (OxMGCM). Results from the model with either a prescribed dust scenario or with assimilation of thermal and dust observations from Mars Global Surveyor's Thermal Emission Spectrometer (MGS/TES) can be used.

In this work we have used the MLAM to simulate mesoscale circulations in the Hellas impact basin region in the vicinity of the perihelion season. As an extension to initial Hellas simulations, both scenario and assimilation type of OxMGCM initial and boundary conditions have been used and comparisons made. Due to the limitations of the current MLAM, the season is chosen to minimise influence of carbon dioxide and water vapour processes. Despite of the lack of dust transport in the model, the focus has still been selected to be in the dust lifting season: as the Hellas basin has such large areas of sloped terrain and since the area is a known dust storm onset region, special emphasis is put on the slope flow characteristics and dust lifting diagnostics.

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