The goal of icecdr is to download sea ice concentration data from the NSIDC Climate Data Record.
You can install the icecdr with:
install.packages("icecdr")Use the cdr_* functions to download satellite-derived
Antarctic or Arctic sea ice concentration data at monthly or daily
resolution. They use version 5 by default but version 4 is also
supported.
The basic usage downloads a NetCDF file in a temporary directory.
library(icecdr)
dates <- c("2020-01-01", "2023-01-01")
cdr_antarctic_monthly(dates, dir = "data", use_cache = TRUE)
#> Returning existing file.
#> [1] "data/995732f34533e77ab2bf32f847c84deb.nc"With use_cache = TRUE, files are only downloaded if
needed.
system.time(cdr_antarctic_monthly(dates, dir = "data", use_cache = TRUE))
#> Returning existing file.
#> user system elapsed
#> 0.019 0.000 0.018There are four simple functions to download whole-domain data:
cdr_antarctic_daily()
cdr_antarctic_monthly()
cdr_arctic_daily()
cdr_arctic_monthly()But the cdr() function exposes all arguments to download
any crazy subset
cdr(date_range = dates,
# Data every 7 days
date_stride = 7,
resolution = "daily",
# Thin the grid by taking every other gridpoint
xgrid_stride = 2,
ygrid_stride = 2,
hemisphere = "north"
)The cdr_fix() function will fix the grid information to
make it work with CDO and standardise
variable names. This requires CDO installed in your system.
library(rcdo)
library(ggplot2)
cdr_antarctic_monthly(dates, dir = "data", use_cache = TRUE) |>
cdr_fix() |>
cdo_fldint() |>
cdo_execute() |>
metR::ReadNetCDF(c("aice")) |>
ggplot(aes(time, aice)) +
geom_line() +
labs(y = "Sea ice area")
#> Warning: Using CDO version 2.4.0 which is different from the version supported by this
#> version of rcdo (2.5.1).
#> ℹ This warning is displayed once per session.
#> Returning existing file.
#> No standard variable name found, returning unchanged file