North American Climate in CMIP5 Experiments. Part I: Evaluation of 20th Century Continental and Regional Climatology

Justin Sheffield, Andrew Barrett, Brian Colle, Rong Fu, Kerrie L. Geil, Qi Hu, Jim Kinter, Sanjiv Kumar, Baird Langenbrunner, Kelly Lombardo, Lindsey N. Long, Eric Maloney, Annarita Mariotti, Joyce E. Meyerson, Kingtse C. Mo, J. David Neelin, Zaitao Pan, Alfredo Ruiz-Barradas, Yolande L. Serra, Anji Seth, Jeanne M. Thibeault, Julienne C. Stroeve J. Climate, submitted 7/30/12.

Preprint (6.2 MB).


Abstract This is the first part of a three-part paper on North American climate in CMIP5 that evaluates the 20th simulations of continental and regional climatology. In general the models capture the main features of North American climate including seasonal precipitation, air temperature and sea surface temperature. The hydrological cycle is also reasonably well simulated for the main characteristics of atmospheric moisture convergence and seasonality of the surface water budget but the latter is subject to the biases in precipitation. The spatial distribution of growing season length and number of frost days are generally well simulated, with biases highest in western regions. The frequency of hydroclimate extreme events is not well represented by the models. Regionally, the skill of the models is variable and can often be attributed to model resolution. The models capture the location of cool season west North Atlantic cyclone density but under predict the magnitude. The models do reasonably well at simulating temperature and precipitation extremes in the southern US, with a tendency to underestimate extreme temperatures and heavy rainfall. The timing and magnitude of the North American monsoon is generally too late and too small in the models. The main features of the summer time Great Plains low-level jet are simulated with model fidelity dependent on resolution. Observed sea ice extent and its decline are generally underestimated. The skill of the multi-model ensemble in capturing the main features of North American climate has not improved significantly since CMIP3, although improvements in some individual models are noticeable.

Citation Sheffield, J. Et al,: North American Climate in CMIP5 Experiments. Part I: Evaluation of 20th Century Continental and Regional Climatology. J. Climate, submitted 7/30/12.

Acknowledgments. We acknowledge the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modeling groups for producing and making available their model output. For CMIP the U.S. Department of Energy's Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. The authors acknowledge the support of NOAA Climate Program Office Modeling, Analysis, Predictions and Projections (MAPP) Program as part of the CMIP5 Task Force.