Regional Climate Simulation for Arizona: Impact of Resolution on Precipitation

This study performs regional climate simulations for Arizona, a region with complicated terrain. The dependence of simulated rainfall on model resolution is explore by climate downscaling experiments using the Weather Research and Forecasting model. The model’s horizontal resolution was refined from 12 to 6, then to 3 km. The total rainfall for winter and for different subdomains of Arizona is found to increase substantially with the refinement from 12 to 6 km grid. A further refinement to 3 km leads to a smaller change in rainfall, indicating numerical convergence at that scale. Comparisons with observations revealed that the 6 and 3 km runs produced excessive rainfall for winter while the 12 km simulations are closer to observation. This implies that the parameterization schemes for rainfall are not resolution independent, thus a refinement of resolution does not guarantee better results. It cautions against hastily pushing for increasingly higher resolution in practical downscaling simulations. An analysis of the simulated hourly rainfall shows that the 3 km runs produce significantly more extreme rainfall events than the 12 km runs. The 6 and 3 km runs also produced more complicated spatial patterns of seasonal rainfall and vertical velocity, reflecting the influence of fine-scale topography.

[1]  Valérie Dulière,et al.  Extreme Precipitation and Temperature over the U.S. Pacific Northwest: A Comparison between Observations, Reanalysis Data, and Regional Models , 2011 .

[2]  F. Giorgi,et al.  Resolution effects on regional climate model simulations of seasonal precipitation over Europe , 2010 .

[3]  Melissa Bukovsky,et al.  Precipitation Simulations Using WRF as a Nested Regional Climate Model , 2009 .

[4]  M. Vuille,et al.  Climate change projections for the tropical Andes using a regional climate model: Temperature and precipitation simulations for the end of the 21st century , 2009 .

[5]  Hans von Storch,et al.  Dynamical downscaling: Assessment of model system dependent retained and added variability for two different regional climate models , 2008 .

[6]  Vincenzo Artale,et al.  Mediterranean water cycle changes: transition to drier 21st century conditions in observations and CMIP3 simulations , 2008 .

[7]  Govindasamy Bala,et al.  Evaluation of a WRF dynamical downscaling simulation over California , 2008 .

[8]  S. Schubert,et al.  North American Monsoon and Convectively Coupled Equatorial Waves Simulated by IPCC AR4 Coupled GCMs , 2008 .

[9]  Zong-Liang Yang,et al.  Assessment of three dynamical climate downscaling methods using the Weather Research and Forecasting (WRF) model , 2008 .

[10]  G. Powers,et al.  A Description of the Advanced Research WRF Version 3 , 2008 .

[11]  Stephen T. Garner,et al.  Simulation of the Recent Multidecadal Increase of Atlantic Hurricane Activity Using an 18-km-Grid Regional Model , 2007 .

[12]  R. Seager,et al.  Model Projections of an Imminent Transition to a More Arid Climate in Southwestern North America , 2007, Science.

[13]  A. Sairouní,et al.  Sensitivity of precipitation forecasts to cumulus parameterizations in Catalonia ( NE Spain ) , 2007 .

[14]  G. Zhang,et al.  Effects of increased horizontal resolution on simulation of the North American Monsoon in the NCAR CAM3: An evaluation based on surface, satellite, and reanalysis data , 2006 .

[15]  R. Arritt,et al.  Simulations of Present and Future Climates in the Western United States with Four Nested Regional Climate Models , 2006 .

[16]  Jinwon Kim.  A Projection of the Effects of the Climate Change Induced by Increased CO2 on Extreme Hydrologic Events in the Western U.S. , 2005 .

[17]  John S. Kain,et al.  The Kain–Fritsch Convective Parameterization: An Update , 2004 .

[18]  Y. Qian,et al.  Hydroclimate of the Western United States Based on Observations and Regional Climate Simulation of 1981–2000. Part I: Seasonal Statistics , 2003 .

[19]  Malcolm K. Hughes,et al.  The climate of the US Southwest , 2002 .

[20]  Raquel V. Francisco,et al.  Emerging patterns of simulated regional climatic changes for the 21st century due to anthropogenic forcings , 2001 .

[21]  Christopher Daly,et al.  Development of a 103-year high-resolution climate data set for the conterminous United States , 2000 .

[22]  C. Woodhouse.  Winter climate and atmospheric circulation patterns in the Sonoran desert region, USA , 1997 .

[23]  F. Giorgi,et al.  A Investigation of the Sensitivity of Simulated Precipitation to Model Resolution and Its Implications for Climate Studies , 1996 .

[24]  F. Hare,et al.  Climates of North America , 1974 .