[ncl-talk] geopotential height calculation

[Barry Lynn]

Laura:

There are many wrf_ncl functions I use (plus get user variables).

Is it possible with MPAS to use similar functions?

Barry

On Wed, Oct 24, 2018 at 5:25 PM Laura Fowler <laura at ucar.edu> wrote:

> Zhifeng:
>
> I just read your ncl question related to the calculation of the 500 hPa
> geopotential height in MPAS. Just wanted to let you know that the vertical
> discretization uses a height coordinate and not sigma (see Klemp (2011) for
> details on the terrain-following coordinate system used in MPAS).
>
> To calculate the 500 hPa geopotential height, you need to use the "height"
> variable zgrid that is written in the init condition file by default if you
> have not saved it in a history file. You also need the "pressure" variable
> which you need to save in your history file. Once you have those 2 fields
> from your outputs, you can use any of the ncl functions int2p, int2p_n, or
> int2p_n_Wrap to interpolate you data to the 500 hPa level.
>
> Note that MPAS also calculates the geopotential height at several fixed
> pressure levels too (see the User's guide on how to use the "diagnostics"
> stream so that you do not have to do that separately.
>
>
> Hope this helps,
> Laura
>
>
> On Tue, Oct 23, 2018 at 3:13 PM Zhifeng Yang <yangzf01 at gmail.com> wrote:
>
>> Hi Adam and Barry,
>>
>> Sorry for less information. The vertical grid in MPAS is sigma. The
>> horizontal grid is Voronoi mesh, unstructured grid. I saw there is a
>> section in NCL processing MPAS model data. I thought MPAS is very common
>> while using NCL. Here I attached the output from ncdump and
>> printVarSummary. There are three types of model output files. diagnos,
>> history, and restart. I am planning to use history output to calculate the
>> geopotential height.
>>
>> I took a look of several wrf related functions in NCL, e.g.
>> wrf_interp_3d_z, wrf_interp_2d_xy. However, they are for latitude-longitude
>> grids, like WRF.
>>
>> Zhifeng
>>
>>
>> On Mon, Oct 22, 2018 at 11:02 PM Barry Lynn <barry.h.lynn at gmail.com>
>> wrote:
>>
>>> Just curious -- have your tried the WRF functions?
>>>
>>> On Mon, Oct 22, 2018 at 11:53 PM Adam Phillips <asphilli at ucar.edu>
>>> wrote:
>>>
>>>> Hi Zhifeng,
>>>> I think more information is needed about your data to answer the
>>>> question. Is your data on hybrid-sigma levels, or some other vertical
>>>> coordinate? Is your data on an unstructured grid, or some other type? A
>>>> printVarSummary of your data would also be helpful.
>>>> Adam
>>>>
>>>> On Mon, Oct 22, 2018 at 1:40 PM Zhifeng Yang <yangzf01 at gmail.com>
>>>> wrote:
>>>>
>>>>> Hi all,
>>>>>
>>>>> I want to get the geopotential height at 500 mb from MPAS model
>>>>> output. Do we have NCL function to calculate it, or other possible methods?
>>>>> Thank you
>>>>>
>>>>> Zhifeng
>>>>> _______________________________________________
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>>>>
>>>>
>>>> --
>>>> Adam Phillips
>>>> Associate Scientist,  Climate and Global Dynamics Laboratory, NCAR
>>>> www.cgd.ucar.edu/staff/asphilli/   303-497-1726
>>>>
>>>> <http://www.cgd.ucar.edu/staff/asphilli>
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>>>
>>>
>>> --
>>> Barry H. Lynn, Ph.D
>>> Senior Associate Scientist, Lecturer,
>>> The Institute of the Earth Science,
>>> The Hebrew University of Jerusalem,
>>> Givat Ram, Jerusalem 91904, Israel
>>> Tel: 972 547 231 170
>>> Fax: (972)-25662581
>>>
>>> C.E.O, Weather It Is, LTD
>>> Weather and Climate Focus
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>
>
> --
>
> !-------------------------------------------------------------------------------------------------------------
> Laura D. Fowler
>
> Mesoscale and Microscale Meteorology Division (MMM)
> National Center for Atmospheric Research
> P.O. Box 3000, Boulder CO 80307-3000
>
> e-mail: laura at ucar.edu
> phone: 303-497-1628
>
>
> !-------------------------------------------------------------------------------------------------------------
>


-- 
Barry H. Lynn, Ph.D
Senior Associate Scientist, Lecturer,
The Institute of the Earth Science,
The Hebrew University of Jerusalem,
Givat Ram, Jerusalem 91904, Israel
Tel: 972 547 231 170
Fax: (972)-25662581

C.E.O, Weather It Is, LTD
Weather and Climate Focus
http://weather-it-is.com
Jerusalem, Israel
Local: 02 930 9525
Cell: 054 7 231 170
Int-IS: x972 2 930 9525
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