Intraseasonal Variation of Winter Precipitation over the Western United States Simulated by 14 IPCC AR4 Coupled GCMs

• Main Authors: Lin, Jia-Lin, Shinoda, Toshiaki, Qian, Taotao, Han, Weiqing, Roundy, Paul, Zheng, Yangxing
• Other Authors: NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
• Format: Text
• Language: English
• Published: 2010
• Subjects: Meteorology; *VALIDATION; *ATMOSPHERIC PRECIPITATION; *ATMOSPHERE MODELS; METHODOLOGY; UNITED STATES; TABLES(DATA); WEATHER FORECASTING; DATA BASES; WINTER; REPRINTS; COMPUTERIZED SIMULATION; SEASONAL VARIATIONS; INTRASEASONAL VARIABILITY; MODEL SIMULATIONS; GCM(GENERAL CIRCULATION MODELS); Byrd; Canada; Pacific; Byrd Polar Research; Byrd Polar Research Center
• Online Access: http://www.dtic.mil/docs/citations/ADA522863; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA522863

This study evaluates the intraseasonal variation of winter precipitation over the western United States in 14 coupled general circulation models (GCMs) participating in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). Eight years of each model's twentieth-century climate simulation are analyzed. The focus is on the two dominant intraseasonal modes for the western U.S. precipitation: the 40-day mode and the 22-day mode. The results show that the models tend to overestimate the northern winter (November-April) seasonal mean precipitation over the western United States and Canada. The models also tend to produce overly strong intraseasonal variability in western U.S. wintertime precipitation, in spite of the overly weak tropical intraseasonal variability in most of the models. All models capture both the 40-day mode and the 22-day mode, usually with overly large variances. For the 40-day mode, models tend to reproduce its deep barotropic vertical structure and three-cell horizontal structure, but only 5 of the 14 models capture its northward propagation, and only 2 models simulate its teleconnection with the Madden-Julian oscillation in the tropical Pacific. For the 22-day mode, 8 of the 14 models reproduce its coherent northward propagation, and 9 models capture its teleconnection with precipitation in the tropical Pacific. Published in the Journal of Climate, v23 n11 p3094-3119, 1 Jun 2010. Prepared in collaboration with the Department of Geography and the Byrd Polar Research Center, The Ohio State University, Columbus, OH; Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO; University at Albany, State University of New York, Albany, NY; and NOAA/ESRL/CIRES Climate Diagnostics Center, Boulder,CO. Sponsored in part by National Science Foundation Grants no. ATM-0745872, OCE-0453046 and ATM-0745897. The original document contains color images. All DTIC reproductions will be in black and white.