Project to Intercompare Regional Climate Simulations (PIRCS): Simulation of the 1993 flood over the central U.S

An important component of climate change impacts assessment is the ability to represent extreme events such as droughts and floods. We have analyzed results from eight regional climate models for simulations over the continental U.S. during 1 June - 31 July 1993, covering the peak precipitation episode during the record-breaking 1993 flood over the central U.S. Analysis focuses on the amount, timing and location of maximum precipitation. Results indicate that the models as a group are able to capture the timing of the flood episode and that the magnitude of the maximum precipitation is generally within 10 to 20 percent of observed amounts. Contributors to the flood, such as low-level jets, also are diagnosed from the archive fields for each model and are used to interpret inter-model differences in simulated precipitation. Comparison to results from a companion study of the 1988 drought using the same ensemble of models suggests first, that the models tend to underrepresent the amplitudes of extreme events (i.e., precipitation is too high during droughts and too low during floods); and second, that model performance as measured by quantitative comparison to observed precipitation tends to be better for floods than for droughts.