3.1 The general circulation of planetary atmospheres as turbulent equilibria

Monday, 8 June 2009: 1:50 PM
Pinnacle BC (Stoweflake Resort and Confernce Center)
Brian Farrell, Harvard Univ., Cambridge, MA; and P. J. Ioannou

A survey of the solar system reveals a variety of turbulent regimes in the large scale circulation of planetary atmospheres. These regimes include convectively forced turbulence in Jupiter's atmosphere and self maintained baroclinic turbulence in the Earth's midlatitude atmosphere. A general theory of turbulent equilibria, Stochastic Structural Stability Theory (SSST), and its expression in mechanistic models for the maintenance of statistically steady turbulent states in planetary atmospheres will be described and applied to obtain the turbulent equilibria that determine the general circulation of Jupiter's atmosphere and of the Earth's midlatitude atmosphere. Among the phenomena explained by the statistically steady fixed points of the SSST system are spontaneous self organization of turbulent flows into large spatial scale jets; geophysical examples of which include the Jovian banded winds and the Earth's polar front jet. Also explained is emergence of marginally stable, highly non-normal equilibria in baroclinic turbulence. These states characterize both observations and simulations of strongly turbulent baroclinic flows and are referred to generically as baroclinically adjusted states. The baroclinically adjusted state is revealed to be not simply a marginally stable state but to have the structure of a specific fixed point equilibrium. In addition it will be shown that these equilibria naturally imply power law relations such as that between heat flux and temperature gradient.
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