[ncl-talk] Full model and Half model height of WRF output

[Bill Ladwig]

Hi Shreeta,

The "height" product from wrf_user_getvar and the half model levels are the
same, since the wrf_user_getvar routines always calculate the values on the
mass grid.  Unfortunately, the description for 'height' says 'full model
levels' but this is a bit of a misnomer, since it's actually the model
levels for the mass grid.  If you want the full model height, just do:

(ph + phb) / 9.81


The example for wrf_interp_1d must have been written before wrf_user_getvar
was implemented.  You should just use the 'height' product from
wrf_user_getvar when you want the height for half levels.

Hope this helps,

Bill



On Thu, Aug 31, 2017 at 11:18 PM, Shreta Ghimire <shreta.g at gmail.com> wrote:

> Dear NCL users,
>
>
> I was trying to calculate full and half model height using WRF output. For
> half-model height i used the formula:
>
>
> z = 0.5*(tmp(0:dimv(0)-2,:,:)+tmp(1:dimv(0)-1,:,:) ; On half (mass) levels
> z at description = "height"
> z at units = "m"
>
>
> that was given in an example of wrf_interp_1d (http://www.ncl.ucar.edu/
> Document/Functions/Built-in/wrf_interp_1d.shtml).
>
>
> To calculate full-model height I used "height" in wrf_user_getvar (
> https://www.ncl.ucar.edu/Document/Functions/WRF_arw/wrf_user_getvar.shtml
> ).
>
>
> The values obtained from both of these are same. Now I am a bit confused
> on what do I need to use to compute the full model height and were they
> suppose to give the same values?
>
>
> Thank you in advance. Any help will be appreciated.
>
>
>
> Regards,
> Shreta
>
>
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