Prof. Peter Read

Abstract:

A new engineering model of the environment of Mars is outlined. The model is based on a database of statistics computed from a state-of-the-art Global Circulation Model of the martian atmosphere which represents our best knowledge of the atmosphere to date. A novel scheme for the representation of large scale variability in the engineering model, in terms of an optimal set of basis functions derived from the Global Circulation Model, is also outlined and shown to be an efficient and accurate method of representing correlated structures in vertical profiles.

Abstract:

A meteorological data assimilation scheme for the martian atmosphere has been implemented and tested, based on techniques used in the current operational scheme for weather forecasting at the U.K. Meteorological Office. The scheme has been interfaced with a range of simple models and with the martian GCM currently under simultaneous development at Laboratoire de Météorologie 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 models, for model validation using earlier martian data, and for data impact studies to assist in planning new missions. Despite proposed new missions to Mars, observations of the atmosphere of Mars in the near future 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 model experiments are conducted in which simulated observations are generated from a second model started from different initial conditions. Such experiments reveal the importance of surface pressure measurements (in combination with an accurate topographic map, such as will be available from laser altimetry) in the determination of the amplitude of large-scale atmospheric waves. It is shown that atmospheric temperature profiles from a remote-sensing instrument on a polar orbiting satellite combined with simultaneous surface pressure observations at a limited number of sites, as planned for the InterMarsNet mission, is a useful scenario for data assimilation. Copyright © 1996 Elsevier Science Ltd.

Abstract:

General Circulation Models, originally developed for the needs of terrestrial meteorology and climatology, have become in the last twenty years a central tool of Martian climate studies. This paper descrcibes how numerical simulation can be also used for determining the environment for a probe. It also highlights the recent modellig efforts which have been made jointly at LMD/CNRS (Paris) and AOPP (Oxford) to develop a new-generation General Circulation Model in order to produce a Martian climate database for the European Space Agency.

Abstract:

A meteorological data assimilation scheme has been developed for Mars, based on techniques used for the current operational scheme at the UK Meteorological Office (UKMO). The scheme has been designed to interface with a range of models of varying complexity, from a simple primitive equations model to a full martian general circulation model with detailed parameterizations of the most important physical processes. The scheme was originally intended to be used primarily for analysis of temperature profiles from the Pressure Modulator Infrared Radiometer (PMIRR) onboard the Mars Observer (MO) spacecraft. It is, however, capable of analysing any asynoptic, randomly-distributed dataset, which may include surface pressure, temperature, velocity or constituent data originating either from other past or future spacecraft missions or from models. It is proposed to use the scheme not only for interpretation of forthcoming data from future spacecraft but also for model inter-comparisons, for hind-casting earlier martian data for model validation and for data impact studies in the planning of new missions. Initial results have demonstrated successful assimilations of trial orbiter and lander data into models with different initial conditions and physics, although a large number of landers might be required if orbiter data were not available. An optimum approach would combine orbiter data with simultaneous measurements from a small number of landers.