Sometimes Simpler is Enough: Representing Cloud-Radiation Effects in Climate Models 


A challenge of climate modeling is to accurately and sufficiently represent complex climate processes.  Although it is well known that clouds scatter and emit radiation in all three dimensions, state-of-the-art global climate models (GCMs) represent atmospheric radiation as simple one-dimensional streams.  DOE scientists have now found that statistics for cloud radiative impacts are almost the same for low-level clouds whether cloud-radiative interactions are represented by one-dimensional or three-dimensional approaches.  This result resolves a longstanding question, demonstrating that the simplified approach taken by GCMs is adequate to obtain realistic low-level cloud properties and that a more complicated treatment of radiation that allows streams in multiple directions may not be required.  This is an important and useful result as climate models continue to increase in complexity and computational intensity.


Matthew Hecht and Hiroyasu Hasumi, editors, 2008: Ocean Modeling in an Eddying Regime. American Geophysical Union Geophysical Monograph Series No. 177, Washington, D.C.