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Eta level height variation

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neel14

Member
Hi,
My question is regarding the variation of eta level heights. Does the level heights vary with time during the simulation?
since eta is a function of pressure and pressure is a variable.
Thanks!
 
Ming Chen said:
Yes the level heights vary with time during the integration.

1. In that case how to get an output at a specified level above ground? Is it possible?
2. Would that mean the volume of that grid would vary with time ? and species concentration would be calculated
using the total integrated mass divided by the changing grid volume?

Pardon me if I am asking noobie questions. Am completely new to WRF.
 
All variables in wrfout are in model levels ( either full or half levels). If you want to get variables at specified levels other than the model levels, you need to do vertical interpolation. Several post-process packages like UPP, RIP, NCL can handle the vertical interpolation. Please take a look at the website here: http://www2.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/index.php. The answer to your second question is yes.
 
Ming Chen said:
All variables in wrfout are in model levels ( either full or half levels). If you want to get variables at specified levels other than the model levels, you need to do vertical interpolation. Several post-process packages like UPP, RIP, NCL can handle the vertical interpolation. Please take a look at the website here: http://www2.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/index.php. The answer to your second question is yes.

Thank you!
 
Hi,
How can I know the height above ground corresponding to a given eta level? Or how can I I define eta levels to correspond to wanted height (e.g: 15m,25m, 60m, ...)?
Thank you.
 
You cannot specify WRF eta levels to specific height levels like 10m, 25m, 50m, etc. This is because WRF implements hybrid vertical coordinate, which is roughly terrain following in lower levels and pressure levels in the upper.

But you can always calculate the height if eta levels based. In wrfinput and wrfout, you can find PH and PHB for each eta level. PH + PHB can give you geopotential height of the eta level.
 
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