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Re: CAPE in NSHARP

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  • Subject: Re: CAPE in NSHARP
  • Date: Wed, 23 Aug 2006 11:29:27 -0600
Guilherme,

NSHARP does use the virtual temperature in the CAPE calculation (through
the parcel subroutine in $GEMPAK/source/programs/gui/nsharp/skparams.c,
pcl.bplus).

The default CAPE (CAPV) shown in the GUI display is the value calculated
from the most unstable level. You can change this through the PARCEL
button to be the surface, or specified level that represents the mixed
layer.

When calculating CAPE (or CAPV- either can be specified) from a sounding
using SNPROF, the user has the ability to define the depth of the layer
(default is !500). For nsharp, you would specify the level that
represents the mixed layer.
Typically, for a sounding showing strong surface heating, the CAPE value
reported using a single surface value would be much higher than when you
specify a level or mixed layer depth that is more representative of the
boundary layer.

Steve Chiswell
Unidata User Support


On Wed, 2006-08-23 at 14:01 -0300, Guilherme Chagas wrote:
> Hi everyone,
> 
> I'm using NSHARP to generate CAPE indices from soundings. However,
> when compared to values generated in MCIDAS theres a considerable
> difference between them, specially with lower values of CAPE. Is
> NSHARP using the virtual temperature correction to calculate stability
> indices? How can I change it (on the source code)?
> 
> Thanks for your help!
> ___________________________
>                 Guilherme O. Chagas
>                               address@hidden
-- 
Steve Chiswell <address@hidden>
Unidata