CopernicusMarine.jl

Julia interface to the Copernicus Marine Toolbox for downloading Copernicus Marine datasets.

Overview

CopernicusMarine.jl drives the standalone copernicusmarine command-line executable. The required executable is a single, self-contained binary that is downloaded automatically on first use — there is no Python, conda, or pip dependency.

Installation

using Pkg
Pkg.add("CopernicusMarine")

Authentication

You need free Copernicus Marine credentials to download data. Either store them once with login:

using CopernicusMarine
login(username="your_username", password="your_password")

or set them in the environment before downloading:

ENV["COPERNICUSMARINE_SERVICE_USERNAME"] = "your_username"
ENV["COPERNICUSMARINE_SERVICE_PASSWORD"] = "your_password"

Usage

Keyword arguments map directly to the toolbox's command-line options (underscores become dashes, e.g. output_directory → --output-directory). Options that accept multiple values, such as --variable, take a vector.

Subset a dataset

using CopernicusMarine

subset(dataset_id = "cmems_mod_ibi_bgc_anfc_0.027deg-3D_P1D-m",
       variable = ["chl", "o2"],
       minimum_longitude = -5, maximum_longitude = -3,
       minimum_latitude = 43, maximum_latitude = 44,
       start_datetime = "2023-09-01", end_datetime = "2023-09-30",
       output_directory = "data")

Download original files

CopernicusMarine.get(dataset_id = "cmems_mod_ibi_bgc_anfc_0.027deg-3D_P1D-m",
                     filter = "*20241221*",
                     output_directory = "data")

(get is not exported because it would clash with Base.get; call it as CopernicusMarine.get.)

Inspect the catalogue

describe returns the catalogue as a parsed JSON object:

catalogue = describe(contains="Global Ocean")

Access the executable directly

exe = CopernicusMarine.executable()   # path to the downloaded binary
run(`$exe subset --help`)

Downloaded data files (NetCDF or Zarr) can be read with packages such as NCDatasets.jl.