MARTIAN ATMOSPHERIC DATA ASSIMILATION WITH A SIMPLIFIED GENERAL-CIRCULATION MODEL - ORBITER AND LANDER NETWORKS

A meteorological data assimilation scheme for the martian atmosphere h as been implemented and tested, based on techniques used in the curren t operational scheme for weather forecasting at the U.K. Meteorologica l Office. The scheme has been interfaced with a range of simple models and with the martian GCM currently under simultaneous development at Laboratoire de Meteorologie Dynamique du CNRS in Paris and at Oxford. As well as the interpretation of data from any future spacecraft, the assimilation scheme may be used for comparisons between different mode ls, for model validation using earlier martian data, and for data impa ct studies to assist in planning new missions. Despite proposed new mi ssions to Mars, observations of the atmosphere of Mars in the near fut ure are still likely to be very sparse compared to those of the Earth (perhaps comprising a single orbiter and a few surface stations at any one time) and the scheme has been adapted with this in mind. Twin mod el experiments are conducted in which simulated observations are gener ated from a second model started from different initial conditions. Su ch experiments reveal the importance of surface pressure measurements (in combination with an accurate topographic map, such as will be avai lable from laser altimetry) in the determination of the amplitude of l arge-scale atmospheric waves. It is shown that atmospheric temperature profiles from a remote-sensing instrument on a polar orbiting satelli te combined with simultaneous surface pressure observations at a limit ed number of sites, as planned for the InterMarsNet mission, is a usef ul scenario for data assimilation. Copyright (C) 1996 Elsevier Science Ltd