Regional Climate Model Projection Credibility for the North American Monsoon

Climate change projections from the North American Regional Climate Change Assessment Program (NARCCAP) suite of regional climate model (RCM) simulations for the North American monsoon system are assessed herein. We focus on changes in precipitation and the many factors effecting the projections. The end goal of our in-depth, process-based assessment is to establish the differential credibility of the ensemble members. In the end, there is a deceptively strong full-ensemble agreement for a decrease in precipitation during the monsoon season. Bias is considerably affecting many of the model projections, and we find that the simulations that are the most biased, in varying ways, in the baseline/current climate, produce the greatest decreases. Problems in the baseline simulations and projections include those related to: atmospheric moisture content, the monsoon high, the Gulf of California low-level jet, tropical easterly waves, the El Niņo Southern Oscillation, precipitation intensity, and other features/phenomena. This presentation will provide a summary of our findings.