ADS functionality

Downloading Data Sets from Copernicus’s Atmosphere Data Store

Copernicus.eu provides a set of interesting data sets for research, education, and applied earth sciences on their Atmospheric Data Store (ADS) as part of the Copernicus Atmospheric Monitoring Service (CAMS). These data provide consistent information on the atmosphere anywhere in the world.

Before Downloading Data

Before you will be able to download any data you need to get a free personal account.

• Register yourself for CDS services
• Terms and conditions

To retrieve data ecmwfr use wf_set_key()to add the login details to your local keyring (requires the R package keyring).

Once you are in possession of your personal user (namely your user ID and a secret key) ecmwfr allows to send requests to CDS and/or download the data.

The Request Syntax

ADS data retrievals are based on a list object which specifies the data set to be downloaded. These definitions are called requests (for those who are familiar with mars: these are basically mars requests). A request defined the type of the dataset, the variables to be downloaded, the time period, output format, target location, a custom area extent, and other details.

The request syntax is available for a range of different CDS data sets. Check the ADS Dataset website to see a list of available datasets and to check whether API requests are allowed or not (go to Download Data, select some data, show request by clicking Show API Request (red button, bottom of page).

The conversion from a python based string to the list format can be automated if you use the RStudio based Addin. By selecting and using Addin -> python to list (or ‘Mars to list’) you dynamically convert queries copied from either ECMWF or CDS based services.

# Specify the data set
request <- list(
  date = "2003-01-01/2003-01-01",
  format = "netcdf",
  variable = "particulate_matter_2.5um",
  time = "00:00",
  dataset_short_name = "cams-global-reanalysis-eac4",
  target = "particulate_matter.nc"
)

# Start downloading the data, the path of the file
# will be returned as a variable (ncfile)
file <- wf_request(user     = "2345",   # user ID (for authentification)
                   request  = request,  # the request
                   transfer = TRUE,     # download the file
                   path     = ".")      # store data in current working directory

# Open NetCDF file and plot
# the log transformed data
r <- raster::raster(ncfile)
raster::plot(log(rotate(r)),
             main = "CAMS reanalysis data (particulate matter 2.5u)",
             col = rev(heat.colors(100)))
maps::map("world", add = TRUE)