Mean meridional circulation driven by eddy forcings of different timescales
- Massachusetts Institute of Technology, Cambridge, MA (United States)
In this paper, the mean meridional circulation (MMC) forced by the eddy fluxes of heat and momentum is examined using a simple two-level model of the zonal-mean atmosphere. Analytical solutions have been obtained, which show that analyses of the eddy-induced MMC using the Kuo-Eliassen equations are most appropriate for high-frequency fluctuations. For steady-state or low-frequency fluctuations, the eddy-fluxes will lead to changes in the zonal-mean zonal wind and temperature. These changes in the zonal-mean state will induce changes in frictional dissipation and diabetic heating, which (together with the eddy-fluxes) are constrained to satisfy a generalization of the Eliassen-Palm theorem and will also act as source terms to the Kou-Eliassen equation. The inclusion of these induced terms usually leads to a significant enhancement in the diagnosed intensity of the MMC. This can explain why previous studies of the MMC found a much weaker eddy-induced Ferrel cell than that observed when the induced frictional and diabetic heating terms were left out and the eddy fluxes were only used as source terms. The relevant timescale separating the high- and low-frequency limits is found to be the radiative timescale in the model. 38 refs., 4 fig., 1 tab.
- OSTI ID:
- 258537
- Journal Information:
- Journal of the Atmospheric Sciences, Vol. 53, Issue 1; Other Information: PBD: 1 Jan 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Eddy heat flux convergence in the troposphere and its effect on the meridional circulation and ozone distribution
The significance of cloud-radiative forcing to the general circulation on climate time scales -- a satellite interpretation