Prof. Peter Read

Abstract:

Data assimilation is a technique for the analysis of atmospheric observations which combines current information with prior knowledge from previous observations, summarized and forecast in time via the use of a numerical model. A sequential data assimilation scheme has been implemented with a full general circulation model (GCM) of the martian atmosphere for the first time, and has been adapted for the types of atmospheric data which might be expected in the near future, e.g. remote-sensed temperature profiles from a polar orbiter mission such as Mars Surveyor '96 and '98. Tests demonstrate the performance of the scheme using artificial data generated from independent model experiments. (C) 1997 COSPAR. Published by Elsevier Science Ltd.

Abstract:

The effect of orographically generated breaking gravity waves is parametrised in a global circulation model of the Martian atmosphere using schemes adapted from terrestrial models. The schemes are 'tuned' by comparing model integrations with and without gravity wave drag with temperatures derived from the Mariner 9 IRIS instrument. Without gravity wave drag the global circulation model temperature field has excessively cold upper level polar regions. Gravity wave drag can correct for such cold temperatures by warming the atmosphere adiabatically via a dynamically induced circulation. The model climatology is significantly improved in the polar regions with the introduction of the parametrisation. (C) 1997 COSPAR. Published by Elsevier Science Ltd.