Tuesday, 11 January 2005
Interannual variability of Great Plains summer rainfall in Reanalyses and NCAR and NSIPP AMIP-like simulations
Interannual variability of summer precipitation and moisture fluxes over the US Great Plains from AMIP simulations of two state-of-the-art models are compared, the NCAR Community Atmosphere Model (CAM2.0), and the NASA Seasonal-to-Interannual Prediction Project (NSIPP) Model; NCEP and ECMWF reanalyses and the US-MEX precipitation analysis are the targets for the simulations. While models do produce precipitation anomalies over the region, there is little temporal consistency with observations. Simulated precipitation anomalies are mostly due to the local recycling of evaporation in both models. On the other hand, observed precipitation anomalies are linked to remote water sources via moisture fluxes from the Gulf of Mexico; the associated moisture flux convergence anomalies are larger than evaporation anomalies in both reanalysis. Preliminary analysis of the recent "frozen" version of the NCAR model (CAM3.0) does not seem to indicate a substantial improvement.