# computing model height/thickness

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##### New member
How do I compute the model vertical layer thickness from the wrf output variables?
I require either the layer full height/model layer thickness parameter

Hi,
This value can differ because thickness varies at each point due to the model being terrain-following.
(PHB + PH)/g gives geopotential on each model (vertical) level.
Then you will need to find geopotential above and below that to obtain thickness, at each grid point.

Just to note: geopotential and velocity are on full levels. All other variables are on half levels.

Thanks for the reply. I am computing the parameter for each vertical level and I am obtaining values of the order of 10 KM for the first level on land and around 20 KM at level 30 on land. Hope the numbers are realistic, as I am new to this computation.

Hi,
No, that is way too high to be reasonable. The thickness will certainly vary, and will increase with height for a while, but you shouldn't be seeing anything above 1km per layer. I'm attaching a plot showing what I've calculated for a basic run, over a water location, and then one over higher altitude. I used 45 levels for this run.

Kelly

#### Attachments

• 45_levels_thickness_land.png
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• 45_levels_thickness_water.png
14.1 KB · Views: 1,238
Many thanks for the plot.I was plotting the absolute value and not the actual difference between the layers...!
Problem solved, I hope.

Hi,
Thank you for letting us know. I'm glad you were able to solve it.