1. Seasonal-to-Interannual Hydroclimate Variability in Reanalyses and Model Simulations Alfredo Ruiz-Barradas, and Sumant Nigam Department of Atmospheric & Oceanic Science University of Maryland Objectives: Assess seasonal hydroclimate variability over North America. Investigation of the atmospheric water-balance over the Great Plains. Interannual variability of summer and winter precipitation over North America.

2. Regressions of Great Plains Precipitation Indices on hydroclimate fields during the warm-season from NARR and CAM3.0’s AMIP simulation Large Precipitation anomalies over the Great Plains are associated with: +Large moisture flux convergence anomalies in NARR; +Large evaporation anomalies in CAM3.0. Those findings suggest different views of the anomalous atmospheric water budget. NARR Precipitation Vertically-integrated Stationary Moisture Fluxes Evaporation CAM3.0

3. Conclusions NARR successfully assimilates precipitation. Unbalanced water budget over the Great Plains in NARR: –Large evaporation in spring and summer. –Weak transient moisture flux convergence. Interannual variability of warm-season rainfall over the Great Plains indicates: –the importance of remote water sources in nature via convergence of moisture fluxes. –State-of-the-art GCMs vigorously recycle precipitation via evaporation, erroneously. Underway Work Analysis of radiative fluxes and Bowen’s ratio to shed light into the causes of the dominance of evaporation over moisture flux convergence in accounting for Great Plains precipitation variability in many GCMs. Analysis of winter precipitation variability over North America.