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20020328: Calculation of CAPE from CD-ROM soundings

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  • Subject: 20020328: Calculation of CAPE from CD-ROM soundings
  • Date: Thu, 28 Mar 2002 12:33:02 -0700
Matthew,

It could be the need to interpolate temperature and dewpoint over 
levels missing data, or something else. Remember that the STNDEX allows you
to specify the depth of the layer from which the lifted parcel
is computed. The default for CAPE is CAPE!500. Verying the depth
of the layer of course can change the computed value especially
if the boundary layer lape rate causes the surface temperature value
or moinsture not to be representative of the layer.

Can you provide me with the soundings for one of the times below.
Snlist output for all levels would be fine.

Steve Chiswell
Unidata User Support





>From: "Matthew Menne" <address@hidden>
>Organization: National Climatic Data Center, NOAA
>Keywords: 200203281838.g2SIc7a22625

>This is a multi-part message in MIME format.
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>Hello,
>
>I am calculating a number of sounding parameters for soundings from the
>CD-ROM "Radiosonde Data for North America".  I used what I believe to be
>your latest version of the fsltogem program to convert from the FSL to
>GEMPAK format.  Using SNLIST, I occasionally get values of CAPE=0 for
>soundings that I think should have non-zero CAPE.  At first I thought
>the it must be that either LFC or EL or both could not be obtained.
>However, I checked a few examples using the NSHARP program and it looks
>like at least in some cases the sounding may be OK, and NSHARP gives
>reasonable values CAPE, the LI, etc.  I'll provide few station/days as
>examples where NSHARP calculates non-zero CAPE and SNLIST calculates
>zero.  They all happen to be from 1996 but this problem occurs in other
>years that I've looked at.
>
>Station (WMO)    Date/Time
>72340                    03/31/1996    0000z
>72451                     05/14/1996  1200Z
>72451                      09/07/1996   1200Z
>72456                    05/25/1996    1200Z
>
>Any ideas regarding what may be happening are most appreciated.
>
>thanks,
>
>Matthew Menne
>
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