Dissipation mechanisms for convection in rapidly rotating spheres
and the
formation of banded structures
Vincent Morin,
Institut de Physique du Globe de Paris, 75252 Paris,
France and Department of
Mechanical and Aerospace Engineering, University of California, San Diego,
9500 Gilman Drive, La Jolla, California 92093-0411.
Emmanuel Dormy
Institut de Physique du Globe de Paris, 75252 Paris, France and
Département de Physique, L.P.S.,
Ecole Normale Supérieure, 75231 Paris, France and C.N.R.S.
Physics of Fluids, 18, 068104 (2006)
Abstract.
We report banded zonal structures in numerical simulations of weakly
nonlinear rapidly rotating convection. A quasigeostrophic model of
convection is used to demonstrate how, in the presence of Ekman pumping,
banded structures can develop immediately above the onset of convection,
and in the absence of developed turbulence. We argue that these bands
necessarily correspond to a regime in which both Ekman pumping and bulk
viscosity equally affect the zonal flow and that their width scales with
the Ekman number E as E1/4.