precipitable_water - data source for Europe

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Joanns S

May 23, 2024, 9:10:47 AMMay 23
to pvlib-python
Hello everyone!

I am using the pvlib.spectrum function where precipitable_water data is needed.
Who can tell me where to get them for Europe?
Are they among ECMWF data and what are they called there. Because so far the search has not been successful.

Thanks in advance! 

Will Hobbs

May 24, 2024, 10:57:15 AMMay 24
to pvlib-python
I think ERA5 (ECMWF) and MERRA-2 (NASA) both have precipitable water, although I have never used it from either, so I'm not 100% sure. 

This discussion might have some helpful info about accessing ERA5 and MERRA-2 data:


Brighton Mabasa

May 24, 2024, 2:33:38 PMMay 24
to Joanns S, pvlib-python

You can calculate precipitable  water using temperature and humidity data.

Some sources of pw (Solcast, CAMS, ERA5)

You can also calculate pw from dew point temperature, if you don’t have dew point temperature information you can also estimate it using temperature and humidity data (see screen shot attached)


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Joanns S

May 24, 2024, 2:33:45 PMMay 24
to Brighton Mabasa, pvlib-python
Thank you so much for the info! 
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