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An assessment of differences in gridded precipitation datasets in complex terrain

TitleAn assessment of differences in gridded precipitation datasets in complex terrain
Publication TypeJournal Article
Year of PublicationSubmitted
AuthorsHenn B, Newman AJ, Livneh B, Daly C, Lundquist JD
JournalJournal of Hydrology
Date Published2017/03
ISBN Number0022-1694
Keywordsclimate trends; gridded forcing data; hydroclimatology; orographic enhancement; precipitation; uncertainty

Hydrologic modeling and other geophysical applications are sensitive to precipitation forcing data quality, and there are known challenges in spatially distributing gauge-based precipitation over complex terrain. We conduct a comparison of six high-resolution, daily and monthly gridded precipitation datasets over the Western United States. We compare the long-term average spatial patterns, and interannual variability of water-year total precipitation, as well as multi-year trends in precipitation across the datasets. We find that the greatest absolute differences among datasets occur in high-elevation areas and in the maritime mountain ranges of the Western United States, while the greatest percent differences among datasets relative to annual total precipitation occur in arid and rain-shadowed areas. Differences between datasets in some high-elevation areas may exceed 200 mm yr-1 on average, and relative differences range from 5-60% across the Western United States. In areas of high topographic relief, true uncertainties are likely higher than the differences among the datasets due to evidence of biases based on streamflow observations. Trend representation in the datasets are sensitive to how temporal inhomogeneities in the underlying precipitation gauge data are handled.

Short TitleJ. Hydrol.
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