Influences of climate change on California and Nevada regions revealed by a high-resolution dynamical downscaling studyReport as inadecuate

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Climate Dynamics

, Volume 37, Issue 9–10, pp 2005–2020

First Online: 14 December 2010Received: 04 April 2010Accepted: 25 November 2010


In this study, the influence of climate change to California and Nevada regions was investigated through high-resolution 4-km grid spacing dynamical downscaling using the WRF Weather Research and Forecasting model. The dynamical downscaling was performed to both the GFS Global forecast model reanalysis called GFS-WRF runs from 2000–2006 and PCM Parallel Climate Model simulations called PCM-WRF runs from 1997–2006 and 2047–2056. The downscaling results were first validated by comparing current model outputs with the observational analysis PRISM Parameter-elevation Regressions on Independent Slopes Model dataset. In general, the dominant features from GFS-WRF runs and PCM-WRF runs were consistent with each other, as well as with PRISM results. The influences of climate change on the California and Nevada regions can be inferred from the model future runs. The averaged temperature showed a positive trend in the future, as in other studies. The temperature increases by around 1–2°C under the assumption of business as usual over 50 years. This leads to an upward shifting of the freezing level the contour line of 0°C temperature and more rain instead of snow in winter December, January, and February. More hot days >32.2°C or 90°F and extreme hot days >37.8°C or 100°F are predicted in the Sacramento Valley and the southern parts of California and Nevada during summer June, July, and August. More precipitation is predicted in northern California but not in southern California. Rainfall frequency slightly increases in the coast regions, but not in the inland area. No obvious trend of the surface wind was indicated. The probability distribution functions PDF of daily temperature, wind and precipitation for California and Nevada showed no significant change in shape in either winter or summer. The spatial distributions of precipitation frequency from GFS-WRF and PCM-WRF were highly correlated r = 0.83. However, overall positive shifts were seen in the temperature field; increases of 2°C for California and 3°C for Nevada in summer and 2.5°C for California and 1.5°C for Nevada in winter. The PDFs predicted higher precipitation in winter and lower precipitation in the summer for both California and Nevada.

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Author: Lin-Lin Pan - Shu-Hua Chen - Dan Cayan - Mei-Ying Lin - Quinn Hart - Ming-Hua Zhang - Yubao Liu - Jianzhong Wang


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