The dependence of hydroclimate projections in snow‐dominated regions of the western United States on the choice of statistically downscaled climate data

Water Resources Research
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Abstract

We assess monthly temperature and precipitation data produced by four statistically based techniques that were used to downscale general circulation models (GCMs) in the Climate Model Intercomparison Program Phase 5 (CMIP5) (Taylor et al., 2012). We drive a simple water-balance model with the downscaled data to demonstrate the effect of the methods on the cold season hydrology of three, snow dominated regions in the western U.S. Independent of substantial variation among the GCM simulations over the regions (maximum range of ~3.5 °C and 50% change in precipitation), the four methods produce disparate high resolution representations of the magnitude and spatial patterns of future temperature and precipitation simulated by the models that range for up to ~3 °C and 30% change in precipitation that propagate into the hydrologic simulations. Temperature-dependent snowfall, accumulation, and melt in the model are sensitive to how atmospheric lapse rates are applied in the gridded observations that are used to remove the bias in raw GCM temperatures. By the end of the century the same downscaling method (Bias Corrected Spatial Disaggregation) yields a loss of cold-season snowpack of 34% over the Greater Yellowstone Area under a constant lapse rate ( 6.5°C km-1), whereas spatially variable lapse rates nearly double the loss to 66%, highlighting the roll of both lapse rates and high elevation stations in the bias correction dataset. The two newest downscaling methods (Multivariate Adaptive Constructed Analogs and Localized Constructed Analogs) preserve the magnitude of change simulated GCMs better than the other methods and the produce comparable hydrologic projections. Because the downscaled data from the methods vary spatially and by GCM, the downscaled data should be evaluated carefully as part of the process of using downscaled climate products to drive hydrological models over the area of interest.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title The dependence of hydroclimate projections in snow‐dominated regions of the western United States on the choice of statistically downscaled climate data
Series title Water Resources Research
DOI 10.1029/2018WR023458
Volume 55
Issue 3
Year Published 2019
Language English
Publisher American Geophysical Union
Contributing office(s) Geosciences and Environmental Change Science Center
Description 22 p.
First page 2279
Last page 2300
Country United States
State Arizona, California, Colorado, Idaho, Montana,Nevada, New Mexico, Oregon, Washington, Wyoming
Other Geospatial Columbia River Basin, Greater Yellowstone Area, Sierra Nevada, Upper Colorado Basin