Revisiting the Surface Energy Balance

The traditional surface energy balance (SEB), which is based on matching upward and the downward sensible and latent heat fluxes, was re-examined by integrating the total energy conservation to a finite volume that includes an atmospheric layer and a bare soil layer, both adjacent to the surface. This yielded several terms in the SEB that have been previously overlooked. Two important thermal energy transfer mechanisms are associated with capillary water flow toward the surface and the surface heat transfer to kinetic energy through non-hydrostatic pressure work. However, these terms are relatively small to explain the surface energy imbalance. Additionally, different physical processes between molecular thermal conduction required by the SEB and mechanically and thermally generated turbulent heat transfers are examined. Ultimately, the surface energy imbalance is found to be mainly associated with thermal energy trapped near the surface as a result of physical characteristics of molecular diffusion and convective mixing without mechanically generated turbulent mixing. Better measurements to investigate thermal energy balance in the atmosphere near the surface are needed.