THE ROLE OF LARGE-SCALE EDDIES IN THE CLIMATE EQUILIBRIUM .2. VARIABLE STATIC STABILITY

Lorenz's two-level model on a sphere is used to investigate how the re sults of Part I are modified when the interaction of the vertical eddy heat flux and static stability is included. In general, the climate s tate does not depend very much on whether or not this interaction is i ncluded, because the poleward eddy heat transport dominates the eddy f orcing of mean temperature and wind fields. However, the climatic sens itivity is significantly affected. Compared to two-level model results with fixed static stability, the poleward eddy heat flux is less sens itive to the meridional temperature gradient and the gradient is more sensitive to the forcing. For example, the logarithmic derivative of t he eddy flux with respect to the gradient has a slope that is reduced from approximately 15 on a beta-plane with fixed static stability and approximately 6 on a sphere with fixed static stability, to approximat ely 3 to 4 in the present model. This last result is more in line with analyses from observations. The present model also has a stronger bar oclinic adjustment than that in Part 1, more like that in two-level be ta-plane models with fixed static stability, that is, the midlatitude isentropic slope is very insensitive to the forcing, the diabatic heat ing, and the friction, unless the forcing is very weak.