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What is the use of the variable CANWAT ?

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I am wondering what's the use of the variable CANWAT output from WRF and how to use it ? :?:
It is descripted in wrfout file as 'canopy water' and unit is 'kg/m2'. But there are no detail about what is the level height and why its unit is that.
I want a variable which can indicate the content of liquid water in air at roughly 10m above the ground, can I derive it by using of CANWAT?
and how to deal with it? could you give some instruction? Thank you very much !
I am sorry to answer late. This post is listed under a different forum topic that I didn't subscribe.
CANWET is the water content within vegetation canopy. The unit of kg/2 is specified for the convenience of computation in LSM physics.
When you say you want the liquid water content at 10m above the ground, do you mean the water content from the ground to 10m height? If you, you can use vapor at 2m to roughly represent water vapor mixing ratio within the layer from the surface to 10m, and then compute the water content by the algorithm:

liquid_water_below_10m = (qv+qc)*airdensity*10

Usually qc below 10m height is zero.