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Hidalgo, H.G., Dettinger, M.D., and Cayan, D.C., 2008, Changes in Aridity in the Western United States: Californa Drought: An Update -- 2008, California Department of Water Resources, State of California, p. 54-59. (on-line report in pdf format, 4148 KB)
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Hidalgo, H.G., Dettinger, M.D., and Cayan, D.C., 2008, Downscaling With Constructed Analogues: Daily Precipitation and Temperature Fields Over The United States: California Energy Commission Report CEC-500-2007-123, 62 p. (on-line abstract or on-line report in pdf format, 2200 KB)
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Three statistical downscaling methods were applied to NCEP/NCAR reanalysis (used as a surrogate for the best possible general circulation model), and the downscaled meteorology was used to drive a hydrologic model over California. The historic record was divided into an "observed" period of 1950–1976 to provide the basis for downscaling, and a "projected" period of 1977–1999 for assessing skill. The downscaling methods included a bias-correction/spatial downscaling method (BCSD), which relies solely on monthly large scale meteorology and resamples the historical record to obtain daily sequences, a constructed analogues approach (CA), which uses daily large-scale anomalies, and a hybrid method (BCCA) using a quantile-mapping...
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This study examines the geographic structure of observed trends in key hydrologically relevant variables across the western United States at ⅛° spatial resolution during the period 1950–99. Geographical regions, latitude bands, and elevation classes where these trends are statistically significantly different from trends associated with natural climate variations are identified. Variables analyzed include late-winter and spring temperature, winter-total snowy days as a fraction of winter-total wet days, 1 April snow water equivalent (SWE) as a fraction of October–March (ONDJFM) precipitation total [precip(ONDJFM)], and seasonal [JFM] accumulated runoff as a fraction of water-year accumulated runoff. Observed changes...
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