ERA5 data can be used to train, evaluate and forecast phenology models (using CMIP routines). The data used in the download sections is ERA5 land which is re-analysis data at a 10km resolution.

# ERA5 example
pr_dl_era5(
  path = "~/Desktop",
  user = "2088",
  product = "era5",
  extent = c(
    50.73149477111302,
    -7.08887567473501,
    40.365567456020266,
    12.748594284373073
    )
  )

# ERA5-land example
pr_dl_era5(
  path = "~/Desktop",
  user = "2088",
  product = "land",
  file = "era5-land.nc",
  extent = c(
    48.345183009475015,
    4.782986565238425,
    45.64153500799514,
    11.44515031394129
  )
)
# format ERA5 data for upscaling
data <- pr_fm_era5(
  path = "~/Desktop/",
  file = "era5-land.nc",
  year = 2019
)
# load the included data using
data("phenocam_DB")

# optimize model parameters
# using daymet data for training
set.seed(1234)
optim.par <- pr_fit(
  data = phenocam_DB,
  cost = rmse,
  model = "TT",
  method = "GenSA"
)

output <- pr_predict(
  optim.par$par,
  data = data,
  model = "TT"
  )

raster::plot(output)
maps::map("world", add = TRUE)