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D.M.G.C. Luz (Observat\'orio Astron\'omico de Lisboa), F. Hourdin (Laboratoire de Meteorologie Dinamique, CNRS, Paris)
Recent studies have shown that transient planetary waves play an important role in the build up and maintenance of the state of superrotation observed in Titan's atmosphere and in the seasonal redistribution of trace species throughout the atmosphere.
With the aim of conducting a global study of Titan's atmosphere before the arrival of the Cassini-Huygens spacecraft in 2004, a general circulation model is currently being developed which takes account of dynamics, aerosol microphysics and atmospheric chemistry. Due to the high numerical cost of such a model, we are developing a 2-dimensional, latitude-altitude axisymmetric version of the general circulation model. In this version, the effect of transient planetary waves must be parameterized.
Recently, we have been investigating those transient waves with a 2-dimensional model of the shallow-water equations on the sphere. Numerical results show a clear relationship between the occurrence of the barotropic instability in the flow and the immediate generation of large scale non-axisymetric transient waves in the atmosphere. A simple model of the dependence of these waves on the flow will be presented, as a first step towards a parameterization.
The author(s) of this abstract have provided an email address for comments about the abstract: dluz@milkyway.cii.fc.ul.pt