Citation: Crimmins, M.A and T.M. Crimmins, 2019. Does an Early Spring Indicate an Early Summer? Relationships between Intra-seasonal Growing Degree Day Thresholds. Journal of Geophysical Research - Biogeosciences.

Contact: Mike Crimmins, University of Arizona, crimmins@email.arizona.edu

Data File Description: The zip file contains six seperate netcdf files. Each file contains a stack of raster grids that are the day of year the specified growing degree day threshold was reached. Each raster layer is a year from 1948 to 2016.
- GDD50_DOY_BaseT10.nc --> Day of year 50 growing degree day threshold was reached (Base 10C)
- GDD250_DOY_BaseT10.nc --> Day of year 250 growing degree day threshold was reached (Base 10C)
- GDD450_DOY_BaseT10.nc --> Day of year 450 growing degree day threshold was reached (Base 10C)
- GDD50_DOY_BaseT0.nc --> Day of year 50 growing degree day threshold was reached (Base 0C)
- GDD250_DOY_BaseT0.nc --> Day of year 250 growing degree day threshold was reached (Base 0C)
- GDD450_DOY_BaseT0.nc --> Day of year 450 growing degree day threshold was reached (Base 0C)

Growing degree day thresholds were calculated using mean daily temperatures derived from daily min/max TopoWx grid (http://www.scrimhub.org/resources/topowx/). The TopoWx grids were resampled from 800m to a nominal resolution of 3.3 km. Script used to download and process TopoWx grids can be found at:
https://github.com/mcrimmins/GDD-climate/blob/master/GDD_tmeanTopoWx_parallel_wDownload.R

Netcdf information
dimensions : 813, 1750, 1422750, 69  (nrow: latitude, ncol: longitude, ncell, nlayers: years, 1948-2019)
resolution : 0.03333333, 0.03333333  (x, y)
extent     : -125.0042, -66.67083, 24.09583, 51.19583  (xmin: longitude, xmax: longitude, ymin: latitude, ymax: latitude)
crs        : +proj=longlat +lon_0=0 +a=6378137 +rf=298.257223563 
names      : X1, X2, X3, X4, X5, X6, X7, X8, X9, X10, X11, X12, X13, X14, X15, ... (yrs: 1948-2016)