[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

19990419: LIFT question


Ray,
The calculation you are trying to do is very easy in grid programs
using the TMST(thte,pres) function, since this function will return 
the temperature along a moist adiabat at a given pressure  and using
thte which you would calculate from your desired starting point.

There is not a similar function for sounding programs, and the 500 mb
level is hard coded in the $GEMPAKHOME/src/gemlib/ps/pslift.f routine-
though you may find LAPS or STAP useful for determining the instability
of a layer- which in effect is what you are using LIFT for.

If you create your own routine for the library, you will need to enter
the name and calling sequence into the $GEMPAKHOME/src/gemlib/pc/pcdfst.f
and pccstb.f routines which call the desired routines found in STNDEX.

Steve Chiswell
Unidata User Support


On Mon, 19 Apr 1999, Unidata Support wrote:

> 
> ------- Forwarded Message
> 
> >To: address@hidden
> >From: Raymond Tanabe <address@hidden>
> >Subject: LIFT question
> >Organization: .
> >Keywords: 199904150342.VAA07563
> 
> Steve,
> 
> I am currently working on a climatology for waterspouts, funnel clouds,
> and tornodoes in Hawaii from 1976-1997 (the climatology for these events
> prior to 1976 was done by Dr. Tom Schroeder).  Anyway, I was looking to
> try and find a correlation between several stability parameters (CAPE,
> LIFT, SWET, TOTL, etc...) and event occurrence but have so far had poor
> results.  LIFT seems to show some promise, but the correlations are still
> weak.  So far it seems that in most cases waterspouts and funnel clouds in
> hawaii are associated with relatively shallow cumulus-type systems, with
> tops rarely going over 8000-9000 feet.  For these cases, it seems
> irrelevant to look at standard LIFT results because they are using 500 mb
> values.  Just a hunch, but is there anyway that GEMPAK can compute lifted
> index values using other pressure levels, such as 850mb and 700mb, or even
> at other reference levels, such as 2000 meters?  I know that for other
> stability parameters such as BRCH you can specify the depth of the layer.
> If this is possible for LIFT, could you please show me what the command
> looks like.  The following is a copy of the SNLIST values I am using now.
> 
>  SNFILE   = 761201.gem
>  AREA     = @lih
>  DATTIM   = 761215/00
>  SNPARM   = tmpc;dwpc;drct;sped
>  STNDEX   = show;lift;swet;kinx;ctot;vtot;totl;cape;brch
>  LEVELS   = 1020-100-25
>  VCOORD   = pres
>  OUTPUT   = f/lih-data/lih_76121500.txt
>  MRGDAT   = YES
> 
> Finally, where is the location of the source code that calculates the
> stablility parameters?
> 
> Mahalo nui loa for any help that you can provide.
> 
> Aloha...Ray Tanabe
> 
> ##########################################
> Ray Tanabe - Graduate Research Assistant
> Pacific ENSO Applications Center
> c/o Department of Meteorology, HIG Room 350
> University of Hawaii - Manoa Campus
> 2525 Correa Road - Honolulu, HI 96822
> Tel: 808-956-2333  Fax: 808-956-2877
> 
> 
> ------- End of Forwarded Message
> 
>