The Sensitivity of the Simulated Normal and Enhanced C02 Climates to Different Heat Transport Parameterizations in a Two-Dimensional Multilevel Energy Balance Model

Abstract

Atmospheric sensible and latent heat fluxes constitute an important component of the total poleward energy transport in the climate system. The authors investigate the relative role of these heat fluxes in normal and enhanced C02 warming scenarios, using a two-dimensional latitude-height multilayer energy balance climate model. The model uses a diffusive scheme to parameterize the heat transports, where the diffusion coefficients are calculated as a function of the temperature gradient. Results of various numerical experiments show that changes in the diffusion coefficients of both the latent and sensible heat fluxes can significantly affect the present (1?C02) equilibrium climate. The difference between the 2?C02 and 1?C02 climate, however, as measured by the simulated difference temperature field, is much more sensitive to changes in the latent heat rather than the sensible beat diffusion coefficients, particularly in the Tropics. The parameterization scheme with temperature-dependent diffusion coefficients is able to resolve the water vapor feedback in the 2?C02 warming, thus enabling simple energy balance climate models to produce results comparable to those obtained by more complex climate models such as general circulation models.