Eddy Heat Diffusivity at Maximum Dissipation in a Radiative-convective One-dimensional Climate Model

[摘要] The hypothesis that the steady state of the climate is constrained to maximize its dissipation is investigated by using a one-dimensional radiative-convective model where the convective fluxes are parameterized following the mixing length theory. The eddy heat diffusivity is chosen to produce the maximum energy dissipation caused by convection (maximum dissipation principle). The state of maximum dissipation due to heat diffusion in a model atmosphere with a fixed vertical profile of specific humidity is obtained for a value of the eddy heat diffusivity, which is in close agreement with that expected for air in stirred conditions. By including the temperature—opacity feedback (i.e., condensable absorbing gas in the infrared with a fixed vertical profile of relative humidity), the state of maximum dissipation is attained for a value of the eddy heat diffusivity that lies within the range of the expected values. In this case, the vertical temperature profile is convectively stable and does not differ in excess from the observed one. Thus, it is suggested that the results here reported represent an ‘empirical’ support to the maximum dissipation principle.

[学科分类] 大气科学