ERA5

Revision as of 22:05, 27 March 2019 by C.carouge (talk | contribs)

ERA5 is a climate reanalysis dataset, covering the period 1950 to present. ERA5 is being developed through the Copernicus Climate Change Service (C3S).

Data processing for ERA5 is carried out by ECMWF, using ECMWFS' Earth System model IFS, cycle 41r2. The name ERA refers to 'ECMWF ReAnalysis', with ERA5 being the fifth major global reanalysis produced by ECMWF (after FGGE, ERA-15, ERA-40, ERA-Interim). The next reanalysis, ERA6, is planned for around 2020.

We are providing a small subset of ERA5 while waiting for a longer term solution to store and manage this big dataset. Currently data is available from 1979 to present. We have covered the period 2000-2018 for all the requested variables and we are in the process of downloading the other years, refer to the ERA% variable list for more details. ERA5 comprises different data stream, we have only a small subset of the surface operative analysis. For the moment we are not considering downloading model or pressure level data as the size of these are quite big and we wouldn't be able to provide enough data to use them to run a model. For more information on ERA5 data refer to the ECMWF website.

If you need other variables for your current research then you can contact us at climate_help@nci.org.au

NB: this is a temporary fix so we will download only variables which are useful for a variety of projects and that are needed now, if you can use ERA-Interim instead or you will be using ERA5 in the future but not in the next few months, then we won't consider your request.


Requests constraints

We will only accept requests for: - data on regular 0.25 by 0.25 lat/lon grid - global region for surface variables - Austral-Asian region for pressure level. The region includes Australia and the Maritime continent and the CORDEX domain and is defined as: Latitude: 20 to -57 Longitude: 78 to 220 NB longitude for the global region is -180 to 180 - analysis data and no ensemble data (analysis includes surface forecast fields such as precipitation). It is currently impossible to provide input data for a climate model You can submit a request for downloading following these criteria. We will only consider requests that specify the exact code/stream etc. You can refer for more information to the documentation here and to the ERA5 catalogue. Be as specific as possible in your request: grib or netcdf format? which forecast steps do you need if you request forecast data? (see ERA5 website)

 

Latest updates

We added minimum and maximum 2m temperature, these surface variables are the first ones available for the entire period 1979 -2018 together with: mean sea level pressure, 2m temperature, convective precipitation and total precipitation.

Known Issues

Known issues from ECMWF website

Dec 7 2018: an error has been discovered affecting the values of the following variables

CDS Dataset ERA5 hourly data on pressure levels from 2000 to present]
Parameters affected U-component of wind, V-component of wind
Level All pressure levels
Time periods affected 01 Jan. 2000 - 31 Dec. 2008
01 Jun. 2018 - present

This problem was caused by the computation of U/V from Vorticity (Vo) and Divergence (D) already interpolated onto a regular grid in CDS. U/V should have been computed from Vo and D in the spherical harmonics representation (the native model representation) and then interpolated to a regular grid before saving to the climate data store.

The problem is now fixed and we have re-downloading the data, download should be completed by the 19 March 2019. From the CDS communication: "During our investigations, we found that wind values are far too low on pressure levels at the poles in CDS, which has been documented as a known issue. Please use winds at neighbouring locations at 89.75 (N/S) and 89.5 (N/S) for Reanalysis and Ensemble members winds instead of 90 (N/S)."

License

ERA5 data is open access and free to download for all uses, including commercial use. As for ERAI and other ECMWF datasets, though, you need to have an account with ECMWF and accept their terms and conditions, in this particular case ERA5 is covered by the Copernicus license

ERA5 on raijin

Surface

data is downloaded as netcdf on a regular 0.25x0.25 longitude/latitude global grid at 1 hr resolution, as available from the Copernicus server. These are the maximum spatial and temporal resolutions possible for this dataset.

/g/data/ub4/era5/netcdf/surface/<variable>/<yr>/<files>

filename: <variable>_era5_global_<from-date>_<to-date>.nc

Pressure levels

data is downloaded as netcdf on a regular 0.25x0.25 longitude/latitude grid at 1 hr resolution, on an Australian region defined as in the criteria.

/g/data/ub4/era5/netcdf/pressure/<variable>/<yr>/<files>

filename: <variable>_era5_aus_<from-date>_<to-date>.nc

NB variable names are as in the ECMWF param tables, our ERAI netcdf files were following where possible the CMIP conventions

Wave surface level

data is downloaded as netcdf on a regular 0.5x0.5 longitude/latitude grid at 1 hr resolution, on a global grid.

/g/data/ub4/era5/netcdf/wave/<variable>/<yr>/<files>

filename: <variable>_era5_global_<from-date>_<to-date>.nc

Requested variables

ERA5 variable list

 

Note on forecasts

Forecasts are accumulated values defined at 20 steps (0-19) starting from times 06.00 and 18.00.

The accumulations are over the hour ending at the forecast step which is a different behaviour from era interim. The 0 step is always zero because it would be the accumulation from timestep and timestep +0 hours (I.e. 06.00 to 06.00)

The others would be for example for precipitation: Time 06.00 Step 1: forecast of accumulated precipitation between 06.00-07.00 Time 06.00 Step 19: forecast of accumulated precipitation between 06.00-01.00+1 day