Effects of convection and clouds on TOA and surface energy budget and on sea surface temperature

Most GCMs and coupled atmosphere-ocean GCMs are unable to get the energy budgets both at the top of the atmosphere and the surface to agree with observations at the same time. Considerable efforts have been spent to understand the cause of bias in the surface energy budget and to alleviate the climate drift problem in coupled atmosphere-ocean GCMs. In this paper, from a different perspective we investigate this problem using a cloud-resolving model (CRM, which resolves cloud-scale dynamics), a single-column model of NCAR Community Climate Model version 3 (CCM3) (SCM, which parameterizes convection and clouds), and observations during TOGA COARE. It is demonstrated that an accurate representation of cloud systems is of great importance to get BOTH the top-of-atmosphere radiative fluxes and the surface energy budget correct. The vertical distribution of cloud condensate fields matters most.

The accuracy of the CRM-derived surface fluxes is tested by using the fluxes to force a one-dimensional (1D) ocean model. The 1D model, together with the surface forcing from the CRM, can simulate the long-term evolution and diurnal variation of the sea surface temperature (SST). This suggests that the atmosphere-ocean coupling requires accurate representation of mesoscale and cloud-scale processes.