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Download sea ice concentration from NSIDC Climate Data Record

Source: R/cdr.R
cdr.Rd

This is a low-level function to download data from PolarWatch's ERDDAP server.

Usage

cdr(
  date_range = c(NA, NA),
  variables = "aice",
  hemisphere = c("south", "north"),
  resolution = c("monthly", "daily"),
  date_stride = 1,
  xgrid_range = c(NA, NA),
  xgrid_stride = 1,
  ygrid_range = c(NA, NA),
  ygrid_stride = 1,
  version = 5,
  format = "nc",
  file = NULL,
  dir = tempdir(),
  use_cache = TRUE
)

Arguments

date_range

Vector of size two with the start and end dates. Supported formats are:

  • A Date or POSIXct/POSIXlt object.

  • A character vector with ISO format dates: c("2020-01-01", "2020-12-31")

  • A character vector with year-month: c("2020-01", "2020-06") (expands to first/last day of month).

  • A character vector with year only: c("2020", "2021") (expands to full year).

variables

Character vector with the variables to fetch. Valid values are

qa

Quality control flag.

stdev

Sea ice standard deviation.

interpolation_spatial

Flag for spatial interpolation.

interpolation_temporal

Flag for temporal interpolation.

aice_bt

Sea ice concentration of the Bootstrap method.

aice_nt

Sea ice concentration of the Nasa Team method.

Although not all variables are available in all versions and all resolutions. The *_nt and *_bt variables are only available in version 4 and the interpolation flags are only available for daily values.

hemisphere

Character with the hemisphere to download. Can be either "south" or "north".

resolution

Character with the temporal resolution. Can be either "monthly" or "daily".

date_stride

Numeric with the temporal stride. A number greater than 1 means to take only the nth date in the series.

xgrid_range

Numeric vector of size 2 with the range of the x dimension.

xgrid_stride

Numeric with the stride of the x dimension.

ygrid_range

Numeric vector of size 2 with the range of the y dimension.

ygrid_stride

Numeric with the stride of the y dimension.

version

Version of the dataset. Can be 4 or 5.

format

Character with the format.

file

Character with the file name to use for download. If NULL, the file name will be constructed by hashing the request URL. Requests consisting in more than one file will append a number.

dir

Directory where to download the file.

use_cache

Logical indicating whether to not perform the download if the file already exist.

Value

Path or vector of paths to the downloaded files.

Examples

if (FALSE) { # \dontrun{
cdr(date_range = c("2022-01", "2022-01"),
    # 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"
    )
} # }