[ncl-talk] NaN value using the wrf_cape_2d function

Thu Apr 7 12:11:51 MDT 2016

Ideally 'filling-in' a grid would be based o physical principles (eg:
standard atmosphers) for vertical filling of T, Z. Other variables are
problematic.

When extending beyond boundaries (horizontal or vertical), remember the
adage: extrapolation is dangerous!

On the Application page under 'Data Analysis', please see "Grid Filling".
There are some examples.

http://www.ncl.ucar.edu/Applications/grid_fill.shtml

Note: the poisson_grid_fill is 'pretty good' at filling in horizontal gaps
in arrays.

However, you should carefully look at results.

Good luck
D

On Thu, Apr 7, 2016 at 11:23 AM, Bill Ladwig <ladwig at ucar.edu> wrote:

> Your units look correct in the script.  Pressure should be in Pa and
> surface pressure should be in hPa.  The C wrapper converts the pressure to
> hPa before calling the fortran routine, which expects hPa.
>
> Do you have missing data values in your data set?  Since those files
> aren't WRF model output files, I'm guessing your data has missing values
> (probably for temperature).  If that's the case, the routine is going to
> use the missing/fill values in the cape routines and crash.  You'll need to
> remove or replace these values with something the algorithm can use (via
> interpolation, std atmosphere, etc).
>
> For the variable inputs to the cape routines, you can do a printVarSummary
> on them to see if they contain missing values.
>
> Bill
>
> On Wed, Apr 6, 2016 at 5:56 AM, Guilherme Martins <jgmsantos at gmail.com>
> wrote:
>
>> Dear Guido,
>>
>> I used in Pa and the result is undef. I sent a e-mail to wrfhelp at ucar.edu
>> .
>>
>> Thanks,
>>
>> Guilherme.
>>
>> Em qua, 6 de abr de 2016 às 07:21, Guido Cioni <guidocioni at gmail.com>
>> escreveu:
>>
>>> Guilherme, you should pose this question on the ncl-talk dedicated to
>>> WRF (wrfhelp at ucar.edu).
>>>
>>> It seems that the problem is related to THTE but, judging from the
>>> code, it appears that this variable is computed based on pressure, so that
>>> if you pass the wrong units you will eventually get a NaN. I think that you
>>> are using hPa instead of Pa judging from the output message that you get (
>>> *1016.5871875000000*). Try to use the correct units and see if you
>>> still get an error. If it’s still the case please try to
>>>
>>>
>>>    - pass to the function only a subset of the data in order to see if
>>>    the vertical levels are too much for the routine to handle. In my case I
>>>    omitted the first 30 upper vertical levels doing that:
>>>    values=wrf_cape_2d(pres(:,31:149,:,:),temp(:,31:149,:,:),qvap(:,31:149,:,:),z(:,31:149,:,:),z(:,149,:,:),pres(:,149,:,:),False).
>>>    I was getting a different error but maybe it’s worth trying also in your
>>>    case..
>>>    - do you have missing values in the data used for the computation of
>>>    CAPE? Please mind that there is no control on missing data in that
>>>    function, so that you need to remove them before.
>>>
>>> Cheers
>>>
>>> P.S. Just for reference, you can found the code of the deprecated
>>> function, which I believe it is included in the new one, here
>>> https://www.ncl.ucar.edu/Support/talk_archives/2010/att-0235/rip_cape.f
>>>
>>> Guido Cioni
>>> http://guidocioni.altervista.org
>>>
>>> On 05 Apr 2016, at 21:35, Guilherme Martins <jgmsantos at gmail.com> wrote:
>>>
>>> Hi users,
>>>
>>> I'm using the wrf_cape_2d function to calculate CAPE. I wrote a script
>>> and when I run it I receive the mesage below.
>>>
>>> *capecalc3d: Outside of lookup table bounds. prs,thte=
>>> 1016.5871875000000                            NaN*
>>>
>>> I compared my units and variables with the link below and everything
>>> it's okay.
>>>
>>>
>>> http://www.ncl.ucar.edu/Document/Functions/Built-in/wrf_cape_2d.shtml#Description
>>>
>>> Can anyone give me any tip?
>>>
>>> My script is in attachment.
>>>
>>> Thanks,
>>>
>>> Guiherme.
>>> --
>>>
>>> ------------------------------------------------------------------------------------------
>>> Dr. Guilherme Martins
>>> Instituto Nacional de Pesquisas Espaciais (INPE)
>>> Centro de Ciência do Sistema Terrestre (CCST) - Prédio CES
>>> Grupo de Superfície-Biosfera-Atmosfera (GSBA)
>>> Telefone (INPE/CP): +55 12 3186-9520 || Celular (TIM): +55 12 98152-8580
>>> E-mail: guilherme.martins at inpe.br || jgmsantos at gmail.com
>>> Skype: guilherme.martins.
>>> Homepage: https://sites.google.com/site/jgmsantos
>>> Currículo Lattes: http://lattes.cnpq.br/5997657584785803
>>>
>>> ------------------------------------------------------------------------------------------
>>>
>>> <ex01_wrf_cape_2d.ncl>_______________________________________________
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>>> --
>>
>> ------------------------------------------------------------------------------------------
>> Dr. Guilherme Martins
>> Instituto Nacional de Pesquisas Espaciais (INPE)
>> Centro de Ciência do Sistema Terrestre (CCST) - Prédio CES
>> Grupo de Superfície-Biosfera-Atmosfera (GSBA)
>> Telefone (INPE/CP): +55 12 3186-9520 || Celular (TIM): +55 12 98152-8580
>> E-mail: guilherme.martins at inpe.br || jgmsantos at gmail.com
>> Skype: guilherme.martins.
>> Homepage: https://sites.google.com/site/jgmsantos
>> Currículo Lattes: http://lattes.cnpq.br/5997657584785803
>>
>> ------------------------------------------------------------------------------------------
>>
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