Monday, 7 July 2014
The energy budgets over land and oceans are key determinants of terrestrial and maritime climates. However, these budgets are still afflicted with considerable uncertainties, and largely differ in their representation in global climate models, particularly at the surface. We combine a comprehensive set of radiation observations with 43 state-of-the-art climate models to infer best estimates for downward solar and thermal radiation averaged over land and ocean surfaces. Over land, where most direct observations are available to constrain the surface fluxes, we obtain 185 and 305 Wm-2 for surface solar and thermal downward radiation, respectively. Over oceans, with weaker observational constraints, corresponding estimates are around 185 and 356 Wm-2. These estimates closely agree, mostly within 3 Wm-2, with the respective quantities independently determined from recent state-of-the-art reanalyses (ERA Interim) and satellite-derived products (CERES EBAF). This remarkable consistency enhances confidence in the determined flux magnitudes, which have traditionally introduced large discrepancies in the energy budget estimates and often hampered an accurate representation of surface climates in models. Considering additionally surface albedo and emission, we infer an absorbed solar and net thermal radiation of 137 and -67 Wm-2 over land, and of 170 and -53 Wm-2 over oceans, respectively. The surface net radiation is thus estimated at around 70 Wm-2 over land and 117 Wm-2 over oceans, which may impose additional constraints on the respective sensible and latent heat fluxes. Combining these surface budget estimates with satellite-determined TOA budgets (CERES-EBAF) results in an atmospheric solar absorption of 76 and 82 Wm-2 over land and oceans, respectively.
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