Total precipitation data

[Tononi Davide]

Dear grads user.

I´m Davide Tononi and i'm doing some research about moisture on structure. For that i need the precipitation data for some cities in different part of Europe.
For the data of precipitation i download from the web page: http://data-portal.ecmwf.int/data/d/interim_daily the data of total precipitation.
This data are every 12 hours so 2 times for day and is the sum of the 12 previous hours.
I've tried to compare this data, downloaded with step 3, with the data of metereological observation and the situation is like this:
        city    Average temperature [ºC]        Average RH [%]  Annual precipitation from INTERIM [mm]  Annual precipitation [mm] from observation
B       Florence        13.7    76      386     920
C       Helsinki        6.3     83      293     653
 Do you know how is possible this difference?
I've tried also to download the data with step 6 and in this case for the city of helsinki the situation change but now is bigger than in the real situation.
        city    Average temperature [ºC]        Average RH [%]  Annual precipitation from INTERIM [mm]  Annual precipitation [mm] from observation
C       Helsinki        6.3     83      1380    653
And if i sum al the precipitation for 10 years for different cities in Europe the sum are very close each other for different cities.

So some of you can explain to me the meaning of the step? Some of you have already use that data and can explain better how is the meaning of this total precipitation?

Thank you so much
Best regards

Davide Tononi
VTT researcher

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