84th AMS Annual Meeting

Wednesday, 14 January 2004
Interannual variability of North America summer precipitation in CAM2.0 and NSIPP AMIP-like simulations
Hall 4AB
Alfredo Ruiz-Barradas, University of Maryland, College Park, MD; and S. Nigam
Interannual variability of summer precipitation and moisture fluxes over North America from AMIP simulations of two state-of-the-art models are compared, the Community Atmosphere Model (CAM2.0), and the NASA Seasonal-to-Interannual Prediction Project (NSIPP) Model. The retrospective U.S. and Mexico precipitation data set, and the NCEP reanalysis are used as targets of the simulations for the 1950-1998 period. The analysis suggests that notable summer precipitation anomalies over the Great Plains are linked to anomalous vertically integrated stationary moisture fluxes from the Gulf of Mexico. AMIP simulations from the models produce significant precipitation anomalies in the Central U.S. but are unable to capture the southerly stationary moisture fluxes from the Gulf of Mexico associated with those events as seen in observations. It is suggested that the moisture transport by transient motions is more active in those models than observations indicate, but that is currently under investigation.

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