Atmospheric tides in a Mars general circulation model with data assimilation

The prominence of thermal tides in the Martian atmosphere has long been recognized, through classical theory, models and observations, including surface pressure records from the Viking and Mars Pathfinder Landers. A unique record of observations over more than two Martian years is now available from the Mars Global Surveyor spacecraft, although since the spacecraft is Sun-synchronous it is difficult to extract information about many tidal modes directly. Data assimilation is a technique by which observations may be combined with a Mars general circulation model (MGCM) to produce a consistent, time-evolving global analysis. Thermal and total dust opacity measurements derived from the Thermal Emission Spectrometer have been assimilated into the Oxford MGCM and the tidal modes analysed from the model surface pressure record produced by this process. Periods around regional and global dust storm events show strong, characteristic tidal signatures in the assimilations.