Generation of zonal flows by Rossby waves in the atmosphere
- 1Institute of Physics of the Earth, 12 3810 Moscow, 10 B. Gruzinskaya Str., Russia
- 2Department of Physics, University of Maryland, College Park, Maryland 20 740, USA
- 3Institut für Theoretische Physik IV, Fakultät für Physik und Astronomie, Ruhr-Univ. Bochum, D-44780 Bochum, Germany
- 4Department of Plasma Physics, Umeå University S-90 187 Umeå, Sweden
Abstract. A novel mechanism for the short-scale Rossby waves interacting with long-scale zonal flows in the Earth's atmosphere is studied. The model is based on the parametric excitation of convective cells by finite amplitude Rossby waves. We use a set of coupled equations describing the nonlinear interaction of Rossby waves and zonal flows which admits the excitation of zonal flows. The generation of such flows is due to the Reynolds stresses of the finite amplitude Rossby waves. It is found that the wave vector of the fastest growing mode is perpendicular to that of the pump Rossby wave. We calculate the maximum instability growth rate and deduce the optimal spatial dimensions of the zonal flows as well as their azimuthal propagation speed. A comparison with previous results is made. The present theory can be used for the interpretation of existing observations of Rossby type waves in the Earth's atmosphere.