This constructed an xyz object which can easily be converted to a raster object with the raster package. Xyz.swe <- cbind(grid, swe.mat) # and for plotting swe Xyz.tmean <- cbind(grid, tmean.mat) # xyz for plotting tmean on April 1st They are paired together in a dataframe with id() and then combined with the vector to be plotted. X and Y coordinates for our tile were retrieved at the start. psgdd5 <- mapply(PSGDD5, tmean.list, ns.index) Plotting Results The PSGDD5() function is called with the mapply() function so that it can simultaneously receive each element, in order, from the tmean.list and ns.index lists. dir 5] - 5 # for days with no-snow and tmean > 5☌, calculate degrees above 5☌Īnn.ns.gdd5 <- sum(ns.gdd5) # sum these 'degree-days' over the year Open a typical daymet netCDF named swe.OP.1980.nc in order to grab some global dimensions. Set a working directory where tmax, tmin, and swe netCDF files are located. Joining Daymet Tiles with NCL Setup and define global variablesįirst, load the required libraries. Two were used in this example prior to executing the following R code.ĭownloading netCDF Files from THREDDS Server provides many useful tools for processing Daymet files. NetCDF files containing daily minimum temperature (tmin), daily maximum temperature (tmax), and daily snow-water equivalent (swe) are used to calculate PSGDD5. The following example uses a mosaic of 4 Daymet tiles to cover the Olympic Peninsula, Washington. Tiles are available in netCDF format here: PSGDD5 is a bioclimatic variable that quantifies the length and intensity of the growing season, where the growing season is defined by days of the year when daily average temperature exceeds 5☌ and no snowpack is present.ĭaymet is a 1km resolution gridded climate model of daily values covering much of North America (Thornton et al. The following R code inputs Daymet netCDF climate grids and computes raster surfaces of a bioclimatic variable called Post-Snow Growing Degree-Days (PSGDD5). Analysis and Visualization of netCDF files with R

Working with net cdf files in r