question about CAPE, LFC calculation in skewt.ncl function

To whomever may be able to help:

I am using the skew-t function in ncl ($NCARG_ROOT/lib/ncarg/nclscripts/csm/skewt_func.ncl) to plot a skew-t for wrf output. The function can draw the outline for CAPE, as well as find its value. I would like to draw a similar outline for CIN, so I attempted to plot a parcel's path (where a parcel is defined at the lowest level pressure and temperature). For computing the parcel's path, I used the dry adiabatic lapse rate below the LCL (whose value I believe is correct) and then the moist adiabatic lapse rate above it. However my parcel does not seem to follow the moist adiabat as drawn on the skew-t, nor does it match up with the outline drawn for CAPE. I believe that the value for the moist adiabatic lapse rate is correct (using the AMS definition found here: http://glossary.ametsoc.org/wiki/Moist-adiabatic_lapse_rate), so I am not sure what is going wrong.

So my question is this:

1) Does anyone know how the CAPE or LFC values are computed in the script skewt_func.ncl? And if so, could you show how it is done, so that I may compare it to how I get my values? The script has functions inside of it that compute it, but I do not see those embedded functions anywhere in it.

2) Is there any ncl function that can compute the pressure for LFC? There is one for LCL (lclvl) but none that I've found for LFC, which would be helpful.

Thank you for your time and energy.

Jeremy
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Received on Mon Jun 23 05:13:03 2014