Paper Reviewed
Lee, H., Kim, J., Waliser, D.E., Loikith, P.C., Mattmann, C.A. and McGinnis S. 2015. Using joint probability distribution functions to evaluate simulations of precipitation, cloud fraction and insolation in the North America Regional Climate Change Assessment Program (NARCCAP). Climate Dynamics 45: 309-323.

Lee et al. (2015) studied regional climate model fidelity by assessing relationships that exist among seasonally-averaged precipitation, cloud fraction and surface insolation -- as determined by the North American Regional Climate Change Assessment Project (NARCCAP) -- and by comparing the results they thereby obtained with real-world observational data that were acquired from both ground stations and satellites, focusing their attention on 14 separate sub-regions of the conterminous United States.

This work revealed, as the six U.S. researchers describe it, that "the skill in capturing these observed relationships varies widely among the NARCCAP regional climate models, especially in the Midwest and Southeast coast regions where observations show weak (or even negative) correlations between precipitation and cloud fraction in winter." In addition, they note that "model performance varies markedly between regions as well as seasons." And, therefore, when all was said and done, they were forced to admit that the "accurate simulation of precipitation, clouds and other variables related to the surface radiation budget still remains a major challenge in climate models."