[ncl-talk] About CAPE and CIN for soundings

[Dennis Shea]

CAPE **is** sensitive to the starting LCL.

About 17 years ago, I tested a number of CAPE codes and the calculated
values varied 'considerably'. To be honest, I have forgotten why I chose
the version I put into NCL. I would be open to altering the code or
including a different one if you can substantiate and document the issues.

--

A number of CAPE (mainly fortran) subroutines are at:
    http://www.cgd.ucar.edu/~shea/CAPE/*
    http://www.cgd.ucar.edu/~shea/rip_cape.f

    The capeThermo.f is the one used by NCL (see: subroutine cape_djs)

    The rip_cape.f was originally written by Mark Stoelinga, U. Washington
     http://www2.mmm.ucar.edu/wrf/users/docs/ripug.htm

Also, you can download all of Kerry Emanuel's codes from:

     ftp://texmex.mit.edu/pub/emanuel/BOOK/

===
NOTE: WRF provides two functions. These call rip_cape.f


===
Let ncl-talk know if you need more information.

Cheers
D

On Mon, Apr 11, 2016 at 5:19 AM, Stavros Dafis <sdafis at cc.uoi.gr> wrote:

> Dear users,
>
> I am trying to find the Fortran code that calculates CAPE, as I cannot
> find it
> in my libraries (I am using ncl 6.2.0). I want to try and fix the problem
> with
> the excessive CAPE and also find the CIN from sounding data. Is there any
> ready
> program to calculate CIN as the cape_thermo one?
>
> I am plotting real data from soundings and I have also noticed the problem
> with
> CAPE. The LCL calculated by ncl is always lower than the actual one and EL
> quite higher.
>
> I do not understand why ncl adjusts the LCL higher than the first guess,
> as I
> saw these lines while debugging the code:
>
>
> cape.f: LCL pressure: original    915.26794433593750       mb
> cape.f: adjusted to    925.00000000000000       mb
> cape.f: and lies at level            4
>
>
> In my data, the actual LCL is at 879mb, but 915mb would be better than
> 925mb.
> Anyway, I need to see the Fortran code to find the problem. Any
> suggestions on
> that? Choose the second guess of LCL?
>
> Furthermore, I would like to propose the following changes at the
> skewt_func.ncl
> code, in order the users to find the LFC and Equillibrium levels, because
> they
> are already calculated but not printed:
>
>
>
>   iprnt = 0   ; debug only (>0)
>    nlLcl= 0   ; LCL
>    nlLfc= 0   ; LFC
>  nlCross= 0   ; EL
>
>  cape = cape_thermo(p,tc,plcl,iprnt)       ; (J/kg)
>
>   tpar = cape at tparcel                      ; temp of the parcel
>   nlLcl= cape at jlcl
>   nlLfc= cape at jlfc
>   nlCross= cape at jcross
>                                           ; Equillibrium Level
> EL_p = p(nlCross)                         ; hPa
> EL_z = z(nlCross) /1000                   ; in km
> EL = decimalPlaces(EL_z,1,True)
> print("EL = "+EL+" km")
>
> LFC_p = p(nlLfc)                         ; LFC in hPa
> LFC_z = z(nlLfc) /1000                   ; in km
> LFC = decimalPlaces(LFC_z,2,True)
> print("LFC = "+LFC+" km")
>
>
>
> --
> Stavros Dafis
> MSc student Atmospheric Sciences and Environment
> University of Ioannina
> LATMOS Laboratoire Atmospheres, Milieux,Observations Spatiales; Versailles,
> France.
> Tel: +30 2651008499,  Mobile: +30 6970420242
> e-mails: sdafis at noa.gr or dafis91 at yahoo.gr or sdafis at cc.uoi.gr
> Weather charts: http://www.metar.gr
> http://www.meteovolos.gr
>
>
>
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