[Wrf-users] Question about levels in wrf

[Brandt Maxwell - NOAA Federal]

Jose,

First of all, I think these should be sigma levels, even though they're
called eta levels in WRF.  The sigma levels are based on pressure, so one
can calculate approximately how many levels would be below the pressure
found at 1 km above the surface (though not this will vary based on surface
elevation, temperature in the layer, among other things).

If you have a surface (for simplicity sake) of 1010 mb and a top of 10 mb
(many of us will have a lower top), then 0,001 in the sigma coordinates
would equate to about 1 mb.  1 km above the surface would be around 900 mb
given the above surface pressure, so you can approximate anything between
sigma levels of .890 and 1.000 to be below 1 km (you can use a standard
atmosphere calculator to see how things like temperature can affect this).
If your model top is really low, like 100 mb, then your 1 km sigma level
would be more like .880.

Later...
Brandt Maxwell
National Weather Service/San Diego




On Sun, Sep 4, 2016 at 4:03 PM, Jose Augusto Paixão Veiga <
veiga.uea at gmail.com> wrote:

> Dear all,
>
> I am using the following eta levels in my runs with WRF (38 in this case).
>
>
>
> *eta_levels                          = 1.000, 0.995, 0.990, 0.985, 0.980, *
>
> *                                      0.970, 0.960, 0.950, 0.940, 0.930, *
>
> *                                       0.920, 0.910, 0.900, 0.880,
> 0.860, *
>
> *                                       0.830, 0.800, 0.770, 0.740,
> 0.710, *
>
> *                                       0.680, 0.640, 0.600, 0.560,
> 0.520, *
>
> *                                       0.480, 0.440, 0.400, 0.360,
> 0.320, *
>
> *                                       0.280, 0.240, 0.200, 0.160,
> 0.120, *
>
> *                                       0.080, 0.040, 0.000*
>
>
>
> However, I would like to know how many levels, in this example, are
> included (a) in the first km and (b) how can I identify the eta level
> representing the first km?
>
> I really appreciate any comment on this issue.
>
> Thanks.
>
>
>
>
>
>
> José Augusto P. Veiga
> CREA n.: 24161
>
> ======================================
> Universidade do Estado do Amazonas
> Departamento de Meteorologia
> Escola Superior de Tecnologia (EST)
> ======================================
> Av. Darcy Vargas, 1200, Manaus-AM Brasil
> Work phone:    (92) 3878 4317, Ramal 4317
> Skype: veiga_j.a.p.
> ======================================
> CV: http://lattes.cnpq.br/4027612512091565
> Site: https://scientificmet.wordpress.com
> ======================================
>
>
>
>
> _______________________________________________
> Wrf-users mailing list
> Wrf-users at ucar.edu
> http://mailman.ucar.edu/mailman/listinfo/wrf-users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ucar.edu/pipermail/wrf-users/attachments/20160906/2d111eee/attachment.html