Three-dimensional radiative transfer makes its mark

Clearly atmospheric three-dimensional (3-D) radiative transfer has crossed the invisible but important threshold that makes it a subject of scientific interest in its own right, and this transition happened almost without anyone noticing. It took an AGU Spring Meeting special session this year on the topic to come to this realization. The outcome was a pleasant surprise for all involved. Three-dimensional radiative transfer is traditionally viewed as a rather specialized subtopic, generally subordinated to some well-defined application. Consider, for instance, this question: “What is the effect of unresolved horizontal variability in cloud structure on energy budgets in general circulation models (GCMs); that is, on fluxes at the grid-cell scale? “This is clearly an important issue and was addressed head-on by Bob Cahalan and Graeme Stephens. The answer currently is anticipated in the form of a bias with respect to predictions based on the standard horizontally uniform cloud models implemented in the GCM parameterizations; this way, fluxes can be readily corrected for 3-D effects.