Accesses the CMIP6 data of the Copernicus API via the
ecmwfr package. Saves the downloaded
files as .zip objects in the specified path in a subfolder with the
coordinates of the downloaded area as subfolder name. You can either specify
the GCMs by name, take the combinations of scenario and GCM that worked in
the past (model = 'default') or you can try out all GCMs for a scenario and
take the ones for which there is data (model = 'all').
download_cmip6_ecmwfr(
scenarios,
area,
user,
key,
model = "default",
service = "cds",
frequency = "monthly",
variable = c("Tmin", "Tmax"),
year_start = 2015,
year_end = 2100,
month = 1:12,
sec_wait = 3600,
n_try = 10,
update_everything = FALSE,
path_download = "cmip6_downloaded"
)NULL, the downloaded files are saved in the stated directory
vector of characters specifying the shared socioeconomic pathway scenarios (SSP) to be downloaded. Currently the values 'ssp126', 'ssp245', 'ssp370' and 'ssp585' are the only accepted options. These are the standard scenarios of CMIP6.
numeric vector of length 4. Sets the spatial boundaries of the downloaded data. Coordinates are supplied in the following format: c(maximum latitude, minimum longitude, minimum latitude, maximum longitude), which corresponds to the northern extent, western extent, southern extent and eastern extent of the area of interest.
a character, user name from the Copernicus climate data store. See 'Details' for more information.
a character. Can be found just beneath the user id on the profile when registering for the Copernicus website. Should be provided as a character (so in quotation marks).
character, by default "default". Decides which global climate models are requested. If set to "default" then depending on the scenario and temporal resolution around 20 models are selected for which we know that certain combinations of scenario and variables are available. If this is set to "all", then all potential models are requested. You can also hand-pick the models you want to download as a vector of the model names. You can check https://cds.climate.copernicus.eu/cdsapp#!/dataset/projections-cmip6?tab=form for the list of models. In case a certain request fails because either the model name is wrong or the requested combination of SSP, time period and variable is not available, then the model is dropped from the requests and the function carries on with the remaining requests. The user will get a warning in these cases.
character, by default 'cds'. Decides which database is used.
For more details see in the documentation of
ecmwfr::wf_set_key().
character, can be either 'daily' or 'monthly'. Sets if the downloaded CMIP6 data is in daily or monthly format.
vector of characters, decides which variables get downloaded. Currently, the options "Tmin" (Daily minimum temperature in degree centigrade), "Tmax" (Daily maximum temperature in degree centigrade) and "Prec" (Daily sum of precipitation in mm) are the only valid options.
numeric, earliest year for downloaded CMIP6 data. By default set to 2015.
numeric, latest year for downloaded CMIP6 data. By default set to 2100.
numeric vector, sets for which months data should be downloaded. By default set to 1:12.
numeric, sets the maximum waiting time per requested file. By default is 3600, so 1 hour.
numeric, number of repeated calls for the API. For more information see 'Details'.
logical, by default set to FALSE. When set to FALSE, scenarios with matching names that have already been downloaded are skipped. If set to TRUE, then files are downloaded regardless if a file with the same name is already present.
character, sets the path for the download of the CMIP6 file. If not already present, then a new folder will be created. The path is relative to the working directory.
Lars Caspersen, Antonio Picornell
Registering for cds.climate.coperincus.eu: https://cds.climate.copernicus.eu/cdsapp#!/home
Finding the user id and the key:
On the website of the Copernicus climate data store, navigate to the user profile and scroll to the bottom to "API key". There you can find the item "UID". The user id should be provided as character (within quotation marks). Just below, you can also find the key, which is also needed when using this function.
After successful registration some extra steps are needed in order to be able to download CMIP6 data. In addition to the "Terms of use of the Copernicus Climate Store" and the "Data Protection and Privacy Agreement", you also need to agree to the "CMIP6 - Data Access - Terms of Use". This needs to be done after registering. You can agree to the terms via the following link: https://cds.climate.copernicus.eu/cdsapp/#!/terms/cmip6-wps.
Alternatively, you can navigate to the terms within the Copernicus webpage. Go to "Datasets", you can find it in the upper ribbon of the main page. There you need to search for "CMIP6" using the search field and choose the first result, which is named "CMIP6 climate projections". There you need to click on "Download data" and scroll to the very bottom of the page to the field "Terms of Use". There you need to click on the button saying "Accept Terms". If you do not accept the terms the download via the API (and consequently via this function) will not be possible!
Sometimes the server is not responding in time, which can make the download fail. In such cases, after a short waiting time of 5 seconds, the request is started again. If the error reoccurs several times, the requested model will be dropped from the list of requests. By default the number of allowed repeated requests is 10. The user will get a warning if the model is dropped from the requests.