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ERA Data from the ECMWF

ECMWF Reanalysis data are available from WDCC/DKRZ as well. This page tells what it is and how it works - for the state-of-the-art data of project ERA5 as well as for the older projects ERA Interim, ERA40, and ERA15.

1. What is ERA ?

ERA is the computerised weather data from the European Centre for Medium-Range Weather Forecasts (http://www.ecmwf.int) by re-analysed and homogenised observation data, taken from scientific relevant observations worldwide. The first two of five projects (FGGE and ERA15) were followed by ERA40 (data 1957-09 to 2002-08), ERA Interim (from 1979 to 2018), and ERA5 (1950 to present). Contracted by the German Meteorological Service (Deutscher Wetterdienst, DWD), the World Data Centre for Climate (WDCC) at DKRZ is the German distributor of a selection of these data.

2. Restrictions on ERA Data

ERA5 data is open access and free to download for all uses, including commercial use, after agreement to the terms of use. At the beginning, The older ERA data has been open for scientific use to registered users only. This is the basis, on which WDCC disseminates them. Since few years, these ERA Interim data may be used commercially as well (see ECMWF website).

In case you need ERA15/40/Interim: See below for registration (Chapter 5: "How to get the data?").

3. What different ERA data do exist ?

The ERA data sets differ in several ways:

  • by temporal resolution:

    ERA5 data has a time resolution of one hour, whereas the earlier ERA Interim and ERA40 produced data of four values a day. Additionally at the CDS and/or ECMWF, monthly means of different hours of the day separately are available, as well as the total monthly mean of all data of a certain parameter. WDCC/DKRZ will try to offer these data later.

  • by spatial resolution:

    For ERA5 the resolution is about 31 km globally, ERA Interim had 79km. We mainly offer ERA data on a Gaussian Grid, few data of the dynamical variables are on a grid of spherical harmonics: for atmospheric fields as model levels, the parameters 130, 135, 138, and 155 are offered this way.

  • by level type:

    ground data have only the level "surface" (sfc), upper air fields of ERA5 can be retrieved for 137/37 different model/pressure levels, ERA Interim is on 60/37 different levels.

  • by forecast step:

    For ERA Interim, forecasts have been calculated for 06,12, ... hours step width. Step width 00 corresponds to pure analysis, i.e., no forecast. For ERA Interim the analysis data (step 00) and forecast steps 03,06,09 and 12 are available.
    Step 00 contains only intensive data (like temperature). Their values refer to the time given in the record header. In addition, forecast steps contain extensive data (like precipitation), which are accumulated from programme start (ERA Interim) as given in the file header or from the previous forecast (ERA5).

  • by physical parameter:

    the data is available for many physical parameters, mostly identified by their numbers as listed in table 128 at ECMWF (see list at ECMWF).

4. What ERA data is retrievable at DKRZ ?

Data is available in the CERA DB for five ERA projects:

Note:

  • In case you do not find the data you need, please contact data(at)dkrz.de
  • ERA5 data are available on disk with about 3 months delay, Information is provided on request (data(at)dkrz.de).

5. How to get the data ?

Find out, what types of data you need: start and end time, time resolution, forecast step, level (surface only, pressure levels, model levels) and physical parameters.

In case you want other than ERA5 data: Fill in the "ecrana form" (found here) to confirm the agreement on data usage and fax to +49-40-460094-106 or send it to WDCC by surface mail.

Finally, apply for an ERA user account at data(at)dkrz.de. For ERA5 apply directly there.

6. Links to Further Information on ERA data

Links to more detailed information at ECMWF:

Coarser data is available from the Public Data Server of the ECMWF on a 2.5° x 2.5° grid.

7. Analysis of ERA data

Available software for data analysis are e.g. the Climate Data Operators (CDO).

For conversions between Gaussian grid and spectral representation use cdo commands: sp2gpl and gp2spl.


 

On the following page you find some technical information on the ERA data.

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