[gradsusr] LFC calculation

[Arlindo da Silva]

On Wed, Apr 20, 2011 at 10:39 AM, Meredith Croke <mcroke at airdat.com> wrote:

> Hi Everyone,
>
> I’m looking to plot a contour plot of LFC height, similar to the graphic on
> the SPC Mesoscale Analysis page, my control file does not output LFC
> directly,  is there anyway I can calculate this in grads?
>
>
>

The opengrads bundle includes a GS-udf function to compute the pressure &
temperature at the lifiting condensation level (plcl, tlcl):

      http://opengrads.org/doc/udxt/saakeskus/

(For implementation, see file plcl.gsf/tlcl.gsf under
Contents/Resources/Scripts.)

>From the LCL, follow the moist adiabatic lapse
rate<http://en.wikipedia.org/wiki/Moist_adiabatic_lapse_rate> until
the temperature of the parcel reaches the air mass temperature, at the
equilibrium
level <http://en.wikipedia.org/wiki/Equilibrium_level> (EL). If the
temperature of the parcel along the moist adiabat is warmer than the
environment on further lift, one has found the LFC. The wikipedia has some
useful information:

     http://en.wikipedia.org/wiki/Level_of_free_convection

If someone comes up with such GS udf for computing the LFC I'd be more than
glad to include it in the next opengrads release. Any volunteer?

   Good Luck,

       Arlindo

-- 
Arlindo da Silva
dasilva at alum.mit.edu
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