Re: wrf_cape_2d

From: wrfhelp <wrfhelp_at_nyahnyahspammersnyahnyah>
Date: Fri May 18 2012 - 13:05:31 MDT

Is this WRF data. If not, we cannot guarantee this will for for other datasets.

If it is WRF data, have you look at all times? As there is no moisture in the model at time 0, this will give -1 values.
Also, I would suggest trying this script - it will do all the calculations for you:
        http://www.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/Examples/DIAGNOSTICS/wrf_cape.htm

Hope this helps
wrfhelp
------------------------------------------------------------------------------
http://www.mmm.ucar.edu/wrf/users/supports/wrfhelp.html

On May 8, 2012, at 10:01 AM, Dennis Shea wrote:

> All the wrf_* functions were written by wrfhelp@ucar.edu.
> This is being forwarded to wrfhelp
>
> Cheers
>
> On 05/08/2012 09:51 AM, jonathan meyer wrote:
>> Hi,
>>
>> I am attempting to plot the four stability parameters output by the
>> function wrf_cape_2d.
>>
>> Looking at the output, the LCL and LFC parameters all look reasonable
>> but the CAPE and CIN parameters are all constant fields of -0.1 so I am
>> hoping to get some guidance from the experts.
>> I have repeated this problem with both version 6.0 and 5.2.
>>
>> I've attached a .txt file showing a single WRF-model grid point's
>> incoming arguments and the 4 output parameters for that specific point
>> to show how the data looks coming in and the problematic CAPE/CIN fields
>> coming out.
>>
>> It seems all the units and ordering are fine for each argument
>> (Pressure: Pa, Temp: K, Q: kg/kg, Z: m, Zsfc: m, and Psfc: hPa).
>> I also do not show any missing values that could influence the output
>> for the single point that I am reporting (see attached ncl.txt file for
>> the actual values). The point falls in central Arizona and is for
>> January 1st.
>>
>>
>> The following is my code snippet that I've cleaned up a bit:
>>
>> NCEPf = addfile (NCEP+NCEPc(nf), "r")
>> NCEPP = wrf_user_getvar(NCEPf, "pres", 0)
>> NCEPT = wrf_user_getvar(NCEPf, "tk", 0)
>> NCEPQ = NCEPf->QVAPOR(0,:,:,:)
>> NCEPZ = wrf_user_getvar(NCEPf, "geopt", 0) ;comes in as m2/s2
>> NCEPZ = NCEPZ / 9.81 ;reduce to units of m
>> NCEPsfc= NCEPf->PSFC(0,:,:) / 100. ; comes in as Pa, reduce to units of hPa
>> NCEPCape = wrf_cape_2d( NCEPP, NCEPT, NCEPQ, NCEPZ, HGT, NCEPsfc, True)
>>
>>
>> Thanks for any advice.
>>
>> Jon
>>
>>
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Received on Fri May 18 13:05:40 2012

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