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<br />4. SUMMARY AND FUTURE STUDIES
<br />
<br />This paper presents an overview of Reclantation's
<br />approach to nested oumerical modeling of precipitation in
<br />western Colorado for GCCRP research. This collaborative
<br />study with NCAR scientists indicates that the regional
<br />MM4 model provides useful climate information for
<br />regional-scale climate simulations; however, nested local-
<br />scale models are needed to resolve local effects of terrain on
<br />precipitation. Time series of observed high elevation
<br />(>2700 m msl) and regional model predicted daily
<br />cumulative precipitation matched reasonably well during
<br />winter months of 1982-83; however, convective periods
<br />diverged significantly. This suggests that MM4's regional
<br />climate simulations may provide useful estimates of winter
<br />cumulative precipitation. A different pattern occurred in
<br />1988 with a good match of model predictions and
<br />observations below 2100 m msl during January and
<br />February; however, this pattern diverged from March to
<br />September. We are currently examining the sources of this
<br />problem.
<br />
<br />Next, we will perform higher resolution nested
<br />Clark model simulations and will begin simulations of
<br />summer monsoon conditions for more complex convective
<br />clouds and precipitation.
<br />
<br />5. ACKNOWLEDGEMENTS
<br />
<br />Sincere thanks is expressed to Drs. Terry Clark and
<br />Bill Hall of NCAR's MMM Division for their assistance in
<br />providing the model code and instructions regarding its
<br />operation and interpretation. The computing was performed
<br />at NCAR, which is sponsored by the National Science
<br />Foundation. Mr. Ra' Aman, Ms. Karen Morris and Ms.
<br />Anne Reynolds of Reclamation's Water Augmentation
<br />Group contributed to analysis software development and data
<br />processing. Messrs. John Lease and Curt Hartzell provid~d
<br />. helpful suggestions regarding the manuscript
<br />
<br />6. REFERENCES
<br />
<br />Anthes, R. A., E. Y. Hsie, and Y. H. Kuo, 1987.
<br />Description of the Penn State/NCAR Mesoscale Model
<br />Version 4 (MM4). NCAR Tech. Note, NCAR{fN-
<br />282+STR, p. 66
<br />
<br />Clark, T. L., 1977. A Small-scale Dynamic Model using a
<br />Terrain-following Coordinate Transformation. J.
<br />Computational Physics, 24, 186-215.
<br />
<br />_,1979: Numerical Simulations with a Three-
<br />dimensional Cloud Model: Lateral Boundary Conditions
<br />Experiments and Multicellular Severe Storms Simulations.
<br />
<br />.... ~-;:-
<br />
<br />J. Almos. Sci. 36, 2191-2215.
<br />
<br />_,W. D. Hall,1991. Multi-domain Simulations of the
<br />Navier-Stokes Equations: BenchmaIk Error Analysis of
<br />some Nesting Procedures. J. Computational Physics,
<br />92, 456-481.
<br />
<br />Dennis, A. S., 1991. Initial Climate Change Scenario
<br />for the Western United States. Bureau of
<br />Reclamation Report, Penver,CO 80225-0007 p. 35
<br />
<br />Giorgi, F., and G. T. Bates, 1989. On the Oimatological
<br />Skill of a Regional Model Over Complex Terrain. M 0 n.
<br />Wea. ReJl., 117, 2325-2347.
<br />
<br />Giorgi, F. and G. T. Bates, and S. J. Nieman, 1992a. The
<br />Multi-year Surface Clirnatology of a Regional Atmospheric
<br />Model over the Western. United States. Submitted to the J.
<br />of Oimate, August 1991.
<br />
<br />Giorgi, F., G. T. BatE:s and S. J. Nieman 1992b. Simulation
<br />of the Arid Oimate o,f the Southern Great Basin
<br />using a Regional Climate Model. Submitted to the
<br />Bulletin of the American Meteorological
<br />Society,
<br />May 1992.
<br />
<br />Matthews, D. A, F. Giorgi, and G. Bates, 1991. Modeling
<br />Regional Controls of Watershed Precipitation for Oimate
<br />Change Studies. PI'l~prints, Second Symposium on Global
<br />Change Studies, AMS Boston, MA. 63-67.
<br />,
<br />
<br />Matthews, D. A, F. Giorgi, and G. Bates, 1992. Regional
<br />Model Simulation of an Extreme Precipitation Event in the
<br />Colorado River Basin. Preprints, Third Symposium on
<br />Global Change Studies, AMS Boston, MA. pp. 20-23.
<br />
<br />Medina, J. G., 1991. Application of a Simple Local-scale
<br />Numerical Model in the Study of Altered Oimate Impacts on
<br />Watershed Precipit:ation. Proc., Second Symposium on
<br />Global Change Stud'ies, AMS Boston, MA. pp. 68-71.
<br />
<br />Medina, J. G., 1992. Simulation of Winter Precipitation in
<br />Western Mountain Watersheds with a Local- scale Model.
<br />Proc., AWRA Symposium on Managing Water Resources
<br />During Global Change Studies, Reno,NV.
<br />
<br />Rhea, J. 0., 1977. Orographic Precipitation Model for
<br />HydrometeorologiCllil Use. Ph. D. Dissertation, Department
<br />of Atmospheric Science, Colorado State University, Ft.
<br />Collins, CO., July 1977. p. 221
<br />
<br />Washington, W. M and G. A Meehl, 1984: Seasonal cycle
<br />experiment on the climate sensitivity due to a doubling of
<br />CO2 with an atmospheric general circulation model coupled
<br />to a simple mixed-Ia.yer ocean model. J. Geophys. Res.,
<br />89,9475-9503.
<br />
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