Solar radiation budgets from 20 general circulation
models (GCMs) participating in the second phase of the
Atmospheric Model Intercomparison Project (AMIPII) are
analyzed. The models largely differ in their global mean
radiation budgets, particularly at the surface. Compared to a
comprehensive data set of 760 worldwide-distributed
surface stations from the Global Energy Balance Archive,
the models tend to overestimate the land surface insolation
by 9 Wm-2 on average. The biases in the net solar fluxes at
the top of atmosphere are generally smaller. This suggests
that the excessive surface insolation in the GCMs is rather
related to inaccurate partitioning of solar absorption
between surface and atmosphere than to excessive
absorption by the planet as a whole. This applies also to
13 state-of-the-art GCMs participating in IPCC AR4.
Uncertainties in the solar absorption by the atmospheric
constituents are thus still significant in current GCMs and
contribute to the large discrepancies amongst the GCM
radiation budgets and their biases compared to surface
observations.

Full Article: http://www.iac.ethz.ch/publications/index?authors=wild

Last Updated: 2007-02-27