Potential Evapotranspiration (PET), Utah and Colorado Plateau - Historic (1968-1999) and Future (2015-2030) (2045-2060)

This dataset is used in the Utah & Colorado Plateau Environmental Evaluation Mapping and Plotting System (EEMAPS), a web mapping application designed for exploring climate projections and fuzzy logic (EEMS) model results for the state of Utah & the Colorado Plateau.

Criteria set forth by the Utah Division of Natural Resources (UT-DWR) and Utah State Office of the Bureau of Land Management (UT-BLM) specified that the time periods used in the analysis be consistent with those used in the Colorado Plateau Rapid Ecological Assessment Report (Bryce et al., 2012), the spatial resolution for the study area be downscaled from 4 km x 4 km pixel resolution to 1 km x 1 km, that data used for future climate projections be obtained from phase 5 of the Coupled Model Intercomparison Project (CMIP5; Taylor et al., 2012), and that the study area be expanded to include the entire State of Utah as well as the Colorado Plateau (Figure 1).
 
The time series climate data used to represent the historical period (1968-1999) were obtained from the LT71m PRISM 30 arc-second spatial climate dataset for the Conterminous United States (Daly et al., 2008).  We evaluated ten of the 34 CMIP5 General Circulation Models (GCMs) that have been shown to reproduce several observed climate metrics such as the Pacific Decadal Oscillation (PDO) and El Niño Southern Oscillation (ENSO) over the study area (Wang et al., 2011; Wang et al., 2014).  Four models (Table 1) were selected that captured the full range of projected change for both annual average temperature and annual precipitation (Figure 2) under the representative concentration pathway 8.5 (RCP8.5; Meinshausen et al., 2011; van Vuuren et al., 2011).  We then obtained downscaled time series climate projections for the selected GCMs from the NASA Earth Exchange (NEX) U.S. Downscaled Climate Projections (NEX US-DCP30) dataset (Thrasher et al., 2013) for the entire spatial extent of the study area and for the period 2015-2060 time. The multi-model ensemble mean of the four downscaled climate models was calculated for each of the climate variables discussed below.

Download the complete Methods document (PDF).

Post-Processing: For analytical purposes, all climate datasets were converted from NetCDF files to geodatabase rasters and subsequently shifted by 0.004166666667 decimal degrees in both latitude and longitude to correct for the shift in the NEX data. Each dataset was then projected to USA_Contiguous_Albers_Equal_Area_Conic_USGS_version_NAD83 at a 1km resolution using a cubic convolution resampling method, and set to snap to the 1km grid used for the UTAH-DWR-COP-BLM climate/intactness project.