Total Precipitable Water Vapor (TQV) and Precipitable Water Vapor (PWV)

[Melra]

TL;DR Summary

Total Precipitable Water Vapor (TQV) and Precipitable Water Vapor (PWV) and what is the difference between them and can one be converted to the other?

I found an opinion that TPW (kg/m2) and PWV (mm) are the same thing, but I only found that kg/m2 = 1 mm and did not find any sources confirming that TPW=PWV. How valid is this? And if they are different things, how do you calculate PWV?

P.S. In general, I need to get the PWV from the data of the MERRA-2, maybe there is another request that you can tell me

 

[BvU]

Hi,

I assume you are reasonably proficient with google or some other search engine. Can you provide links ? To us

I found an opinion

can be anything from the supreme court to someone's five year old nephew !

I find the NASA website pretty impressive; surely they must clearly define what the data represents ?

$\$

 

[Baluncore]

I found an opinion that TPW (kg/m2) and PWV (mm) are the same thing, but I only found that kg/m2 = 1 mm and did not find any sources confirming that TPW=PWV. How valid is this?

It is valid.
Based on the density of water, they are equivalent.
1 m³ of water weighs 1000 kg.
1 mm per m² is 1 litre, which weighs 1 kg.

So they are the same, but one is specified as a mass, the other as a volume, specified as a depth of water. I am ignoring the coefficient of thermal expansion.

 

[Melra]

So they are the same

Okay, they can be reduced to one dimension. But are PWV and TQV the same thing?

 

[Baluncore]

But are PWV and TQV the same thing?

Obviously not. They have different names.

TPW is more accurate, and temperature independent, it specifies precipitate by mass in kg/m².

PWV is not as accurate, but it tells us how much rain we might get, since rainfall is also measured in mm, over an unspecified area.

https://en.wikipedia.org/wiki/Precipitable_water