International Research Institute/Applied Research Centers (IRI/ARCs) regional model intercomparison over South America

[1] A regional modeling intercomparison project for South America among the ( 1) Scripps Experimental Climate Prediction Center regional spectral model (RSM), ( 2) Florida State University nested regional spectral model (FSUNRSM), ( 3) Goddard Institute for Space Studies regional climate model (RCM), and ( 4) IRI regional climate model (RegCM2) is described herein. All regional models were driven by the NCEP/ NCAR I global reanalysis over a South American domain centered on Brazil. In comparison to new Xie and Arkin 0.5degrees land observations, the regional models had a seasonal systematic precipitation error that was somewhat similar to the driving NCEP/ NCAR reanalysis systematic error, although the regional model ensemble mean error was somewhat smaller, indicating a potential value for using multiple model ensembles. However, correlations, threat scores and biases were not noticeably better. In short, at their current levels of skill, regional models do not yet provide a noticable improvement over large-scale analyses.