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Those with root access, or that have already configured a working python environment can go tho the next session.

To fully cover the topic of installing virtual environments, users can look at this tutorial Using virtual Python environment.

Users that want to permanently and quickly access the virtual environment have to create a file $HOME/.bashrc and put the following content in it.

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Or in case of root install sudo pip install cdsapi

Installing the API using conda

/<install_path>/conda/anaconda2/bin/conda config --add channels conda-forge
/<install_path>/conda/anaconda2/bin/conda install cdsapi

For non linux/mac users

The point is to download and install your favorite python version then install the command pip, following common instructions, set up the command line environment to point to python and pip and then run pip install cdsapi.

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Registered users can access https://cds.climate.copernicus.eu/api-how-to and locate the fieeld field named "Install the CDS API key" .

The two lines specifying url and key must be copied ina in a specific file: $HOME/.cdsapirc

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For users using non ECMWF's computers (windows and othere other notebooks) this step is not necessary.

In order to use the web api we need that in the environment running it the proxy settings are deactivated (this is because the CDS is within the premesispremises)

To achieve this goal, in the console with the cdsapi environment type:

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The 2 examples presented in https://cds.climate.copernicus.eu/api-how-to  are a good and simple examples working under unix like systems

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In case the user is using python under windows, the script need needs to be changed.

The change involve onlu involves only the code line c = cdsapi.Client()

It must may be changed in:

This method for providing the credentials may be considered bad practice, because a user will put in plane text his credentials.

A more safe way usable also in all platforms is to set up 2 environmental variables with the required informations:

CDSAPI_URL
CDSAPI_KEY

More hands-on example:

#!/usr/bin/env python
import cdsapi
from datetime import datetime, timedelta
from dateutil.relativedelta import relativedelta

p_levels = [str(z)  for z in ([1] + list(range(50, 1050, 50)))]
c = cdsapi.Client()


def days_of_month(y, m):
    d0 = datetime(y, m, 1)
    d1 = datetime(y, m + 1, d0 + relativedelta(months=1)
    out = list()
    while d0 < d1:
        out.append(d0.strftime('%Y-%m-%d'))
        d0 += timedelta(days=1)
    return out

for y in range(2008, 2018):
    for m in range(1,13):
        for d in days_of_month(y, m):
            c.retrieve("reanalysis-era5-pressure-levels",
                       {
                           "variable": "temperature",
                           "pressure_level": p_levels,
                           "product_type": "reanalysis",
                           "date": d,
                           "time":[
                               '00:00','01:00','02:00',
                               '03:00','04:00','05:00',
                               '06:00','07:00','08:00',
                               '09:00','10:00','11:00',
                               '12:00','13:00','14:00',
                               '15:00','16:00','17:00',
                               '18:00','19:00','20:00',
                               '21:00','22:00','23:00'
                           ],
                           "format": "netcdf"
                       },
                       "ea_t_{day}.nc".format(day=d)
                       )

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