We made an attempt to further constrain the magnitudes of the surface radiative components with largest uncertainties, namely the surface downward solar and thermal fluxes. Complementary to the approaches using satellite-derived products as references we make extensive use of the growing number of surface observations to constrain the radiative components at the Earth's surface. These observations stem from the Global Energy Balance Archive (GEBA) and the Baseline Surface Radiation Network (BSRN). We combine these observations with the latest global modeling efforts performed within the Coupled Model Intercomparison Project Phase 5 (CMIP5) to infer best estimates for the global mean surface radiative components. A regression between the model calculated global mean fluxes and their respective biases compared to the surface observations suggests global mean values of downward surface solar and thermal radiation near 185 and 342 Wm-2, respectively, to be most compatible with surface observations. It is encouraging that these estimates, which make full use of the information contained in the surface networks, coincide within 2 Wm-2 with the latest satellite-derived estimates from CERES-EBAF (Kato et al. 2013), which are completely independently determined. Combined with an estimated global mean surface absorbed solar radiation and thermal emission of 161 Wm-2 and 398 Wm-2, respectively, this leaves around 105 Wm-2 of surface net radiation globally available for the distribution amongst the non-radiative surface energy balance components. This may impose additional constraints on the global mean sensible and latent heat fluxes and associated hydrological cycle.
Kato, S., Loeb, N.G., Rose, F.G., Doelling, D.R., Rutan, D.A., Caldwell ,T.E., Yu, L., and Weller, R., 2013: Surface irradiances consistent with CERES-derived top-of-atmosphere shortwave and longwave irradiances. J. Clim. 26, 2719-2740
Wild, M., Folini, D., Schär, C., Loeb, N., Dutton, E.G., and König-Langlo, G., 2013: The global energy balance from a surface perspective, Clim. Dyn., 40, 3107-3134, Doi:10.1007/s00382-012-1569-8.
Wild, M., Folini, D., Schär, C., Loeb, N., Dutton, E.G., and König-Langlo, G., 2013: A new diagram of the global energy balance, AIP Conf. Proc., 1531, 628-631, doi: 10.1063/1.4804848.