ERA-Interim: What is the difference between TCWV (Total Column Water Vapour) and VIWV (Vertical Integral of Water Vapour)

ERA-Interim production stopped on 31st August 2019

For the time being and until further notice, ERA-Interim (1st January 1979 to 31st August 2019) shall continue to be accessible through the ECMWF Web API.

ERA5 is now available from the Climate Data Store (CDS) (What are the changes from ERA-Interim to ERA5?) and users are strongly advised to migrate to ERA5 (How to download ERA5).

TCWV (Total Column Water Vapour) and VIWV (Vertical Integral of Water Vapour) are essentially the same, but produced by different software.

TCWV is produced by the IFS (ECMWF forecast system) and is available in the analyses and forecasts.

VIWV is produced by the ERA post processing budget software and, for ERA-Interim, is only available in the analyses.

More information is available in the ERA-Interim archive document:

http://www.ecmwf.int/en/elibrary/8174-era-interim-archive-version-20

Both TCWV and VIWV are in kg m^-2.

This document has been produced in the context of the Copernicus Climate Change Service (C3S).

The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of C3S on behalf of the European Union (Delegation agreement signed on 11/11/2014). All information in this document is provided "as is" and no guarantee or warranty is given that the information is fit for any particular purpose.

The users thereof use the information at their sole risk and liability. For the avoidance of all doubt, the European Commission and the European Centre for Medium-Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view.

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This document has been produced in the context of the Copernicus Climate Change Service (C3S).

The users thereof use the information at their sole risk and liability. For the avoidance of all doubt, the European Commission and the European Centre for Medium-Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view.

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