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  • Ruiz-Barradas, A., and S. Nigam, 2006: IPCC’s 20th Century Climate Simulations: Varied Representations of North American Hydroclimate Variability. Journal of Climate, 19, 4041-4058.

The annual cycle of precipitation and the interannual variability of the
North American hydroclimate during summer months are analyzed in coupled
simulations of the twentieth-century climate. The state-ofthe-art
general circulation models, participating in the Fourth Assessment Report
for the Intergovernmental Panel on Climate Change (IPCC), included in the
present study are the U.S. Community Climate System Model version 3
(CCSM3), the Parallel Climate Model (PCM), the Goddard Institute for
Space Studies model version EH (GISS-EH), and the Geophysical Fluid
Dynamics Laboratory Coupled Model version 2.1 (GFDL-CM2.1); the Met
Office's Third Hadley Centre Coupled Ocean-Atmosphere GCM (UKMOHadCM3);
and the Japanese Model for Interdisciplinary Research on Climate version
3.2 [MIROC3.2(hires)]. Datasets with proven high quality such as NCEP's
North American Regional Reanalysis (NARR), and the Climate Prediction
Center (CPC) U.S.-Mexico precipitation analysis are used as targets for

Climatological precipitation is not easily simulated. While models
capture winter precipitation very well over the U.S. northwest, they
encounter failure over the U.S. southeast in the same season. Summer
precipitation over the central United States and Mexico is also a great
challenge for models, particularly the timing. In general the UKMO-HadCM3
is closest to the observations.

The models' potential in simulating interannual hydroclimate variability
over North America during the warm season is varied and limited to the
central United States. Models like PCM, and in particular UKMO-HadCM3,
exhibit reasonably well the observed distribution and relative importance
of remote and local contributions to precipitation variability over the
region (i.e., convergence of remote moisture fluxes dominate over local
evapotranspiration). However, in models like CCSM3 and GFDL-CM2.1 local
contributions dominate over remote ones, in contrast with warm-season
observations. In the other extreme are models like GISS-EH and
MIROC3.2(hires) that prioritize the remote influence of moisture fluxes
and neglect the local influence of land surface processes to the regional
precipitation variability.

Full Article: http://www.atmos.umd.edu/~alfredo/ipcc_ams_final.pdf

Last Updated: 2007-05-29

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