ERA5-Land

Introduction

ERA5 is a global product and widely used for analysing past climate conditions and trends from the 1950s to the present. There are many different datasets and variables produced under the umbrella of ERA5, this post only deals with ERA5-Land monthly averaged data from 1950 to present. The monthly data is a compilation of ERA5-Land hourly data.

ERA5-Land

ERA5 is produced with hourly estimates of a large number of atmospheric, land and oceanic climate variables. A complete list of the main variables (of which some are available at vertical sections) is available HERE. As mentioned above, this post focuses on the ERA5-Land compiled to monthly averaged data from 1950 to present.

The native spatial resolution of the ERA5-Land reanalysis dataset is 9km on a reduced Gaussian grid (TCo1279). The ERA5-land data available via CDS has been regridded to a regular lat-lon grid of 0.1x0.1 degrees. While the core ERA5 data is available from 1959 and is updated within 3 months or real time, the ERA5-Land is extended back to 1950, but with the first years considered preliminary. For details on ERA5, see the page on ERA5: data documentation.

NOTE that ERA5 data is very popular and the queueing time might be exorbitant. Try to download over weekends instead. And chose datasets that cling together as outlined in the troubleshooting page My request is queued for a long time - Web API FAQ and elsewhere.

Access ERA5

If you want to jump right in and check out the ERA5 datasets at CDS.

ERA5-Land ERA5-Land monthly averaged data

The overview tab at the ERA5-Land monthly averaged data from 1950 to present page contains a complete list of the available data variables.

Download dataset

From the overview page ERA5-Land monthly averaged data from 1950 to present, select the tab Download data, as illustrated to the right.

Note that it is easier to download a single variable in each “order”. If you download multiple variables you need to keep track of which variables you did choose in order to disentangle the file you will receive.

Select datasets to download

Select the Product type to download.

Select the Variable you want to retrieve; Total precipitation in the example below. As mentioned above there are some advantages with selecting a single variable with each order.

Set the Year and Month to retrieve. Here it is better to select the full time span and full temporal resolution with each order.

You also have to set Time, which for monthly averade data is defaulted to 00:00.

You can set the Geographical area or accept the default global region.

Available Format options for downloading are GRIB, NetCDF (experimental) and NetCDF-3 (experimental, not recommended). In the example below GRIB is selected.

Accept the Terms of use if you agree to them.

API

With all the required fields selected, the button Show API request should turn green. Click on it to see the API python code:

import cdsapi

c = cdsapi.Client()

c.retrieve(
    'reanalysis-era5-land-monthly-means',
    {
        'product_type': 'monthly_averaged_reanalysis',
        'variable': 'total_precipitation',
        'year': [
            '2010', '2011',
        ],
        'month': [
            '01', '02', '03',
            '04', '05', '06',
            '07', '08', '09',
            '10', '11', '12',
        ],
        'time': '00:00',
        'format': 'grib',
    },
    'download.grib')

If you are using Karttur’s GeoImagine Framework, with the package cdsapi installed, you can run the script above from within the Framework. The instructions for how to setup a non-Framework embedded retrieval using cdsapi, see the Copernicus page on How to use the CDS API.

Some of the ERA5 data is preprocessed and available online, and some need to be processed prior to downloading. In case you order data that needs to be processed you can check the status at https://cds.climate.copernicus.eu/live/queue.