Abstract
Fundamental dynamics of two-dimensional atmospheric general circulations symmetric about the rotation axis of planets is investigated to obtain a wide perspective from the Held and Hou model of the Hadley circulation to the Venus super-rotation driven by the Gierasch mechanism. A parameter sweep experiment is performed to explore steady solutions of the axisymmetric primitive equations of the Boussinesq fluid on a rotating sphere. Sweep parameters are the external thermal Rossby number (R_T), the horizontal Ekman number (E_H), and the vertical Ekman number (E_V). Two indices are introduced to make a dynamical analysis of the numerically obtained circulations: a measure of the intensity of super-rotation and a measure of rigid rotation. The characteristics of steady solutions change largely in a certain range of EH for given RT and EV. Approximate positions of this transition can be estimated theoretically as E_H ~ E_V*R_T for R_T < 1 or E_H ~ E_V*R_T^(1/2) for R_T > 1. We will discuss the comparison between behavior of this 2D model and that of 3D model, focusing the effect of asymmetric large eddies on zonally averaged meridional circulation.
Related Links
- http://www-mete.kugi.kyoto-u.ac.jp/hiroki/file/nctam-submit.pdf - ''Axisymmetric Steady Solutions in an Idealized Model of Atmospheric General Circulations: Hadley Circulation and Super-rotation'' Theoretical and Applied Mechanics Japan (submitted version)