TABLE 1.

Basic characteristics of precipitation sources used in this study.

Characteristics	NLDAS	GLDAS	DAYMET	PRISM	GHCN-D (NCDC)
Source	NASA with collaborations (NOAA, Princeton University, University of Washington)	NASA with collaborations (NOAA, Princeton University, University of Washington)	Oak Ridge National Laboratory (developed by University of Montana/Peter Thornton)	Climate Group of Oregon State University	NOAA/NCDC
Product type	Interpolated	Interpolated	Interpolated	Interpolated	Gauged data
Interpolation method	Bilinear interpolation of NCEP- NCAR Reanalysis (Kalnay et al. 1996) adjusted for elevation using PRISM methodology, temporally disaggregated to one hour (Xia et al. 2012)	Similar to NLDAS	Geographically weighted regression (Thornton et al. 1997)	Geographic- and elevation-weighted regression, station weighting by topography, distance to coast, atmospheric factors (Daly et al. 2008)	Not applicable
Spatial resolution	0.125° × 0.125°	0.25° × 0.25°	1 × 1 km	2.5 arcmin (~4 × 4 km)	Not applicable
Spatial coverage	North America (U.S., southern Canada and northern Mexico)	Global	North America	The conterminous U.S. Global
Temporal resolution	Hourly and monthly	Three-hourly and monthly	Daily	Daily, monthly	Daily
Temporal coverage	1979-present	2000-present	1980-present	1981-present	1880 to present (not in all stations)

Notes: NLDAS, North American Land Data Assimilation System; GLDAS, Global Land Data Assimilation System; DAYMET, Daily Surface Weather and Climatological Summaries; and PRISM, Parameter-elevation Regressions on Independent Slopes Model; NASA, National Aeronautics and Space Administration; NOAA, National Oceanic and Atmospheric Administration; NCEP, National Center for Environmental Prediction; NCAR, National Center for Atmospheric Research.