What is the difference between TCWV (Total Column Water Vapour) and TCW (Total Column Water


I would like to use the ERA-Interim data to evaluate precipitable water. Note that TCWV and TCW are all related to water. However I don't know the difference between the two variable.   Although I had read this page,  and found the ERA-Interim archive document: http://www.ecmwf.int/en/elibrary/8174-era-interim-archive-version-20

The document gives the equation of TCWV, however ,the equation of TCW was not given.  I calculated the value of TCW-TCWV, the result is always positive. Does it means the TCW contains the vertical integerations of water in all phases? Thanks in advance.


please have a look at the following links:



Hope this helps.


Dear Micela,

Thank you for your reply. I got it.