Gridded 20km Daily Reference Evapotranspiration for the State of Alaska from 1979 to 2017

Reference evapotranspiration (ET0), like potential evapotranspiration, is a measure of atmospheric evaporative demand. It was used in the context of this study to evaluate drought conditions that can lead to wildfire activity in Alaska using the Evaporative Demand Drought Index (EDDI) and the Standardized Precipitation Evapotranspiration Index (SPEI). The ET0 data are on a 20km grid with daily temporal resolution and were computed using the meteorological inputs from the dynamically downscaled ERA-Interim reanalysis and two global climate model projections (CCSM4 and GFDL-CM3). The model projections are from CMIP5 and use the RCP8.5 scenario. The dynamically downscaled data are available at https://registry.opendata.aws/wrf-alaska-snap/. The ET0 was computed following the American Society of Civil Engineers Standardized Reference Evapotranspiration Equation based on the downscaled daily temperature, humidity and winds. The full details of the computation of ET0, an evaluation of the underlying data, and the assessment of the fire indices are described in Ziel et al. (2020; https://doi.org/10.3390/f11050516).