[ncl-talk] error in pot_temp_equiv

[Carl Schreck]

Hi Jonathan,

Thanks, I was also getting some values in the tropics that didn't match up
with others studies. It's been on my todo list to dig in and see why, but
it sounds like you might have already done it.

I'm on travel now, but do you have an alternative NCL function we could
test using Bolton?

Thanks!
Carl

On Tue, Nov 14, 2017 at 5:16 PM, Buzan, Jonathan R <jbuzan at purdue.edu>
wrote:

> Hi NCL-Talk,
>
> I was checking out the pot_temp_equiv function in NCL.  Unfortunately, I
> believe I found an error.  https://www.ncl.ucar.edu/Document/Functions/
> Contributed/pot_temp_equiv.shtml
> The descriptions page states it uses Davies-Jones (2009) for the
> calculation.  However, looking at the contributed file, the code uses Stull
> 1988 §13.1 p. 546, which does not use the lifting condensation temperature.
>
>
> I use Bolton 1980 equation 22 for lifting condensation temperature and
> equation 39 for equivalent potential temperature.
> Using typical warm pool values, T = 27°C-31°C, and an average humidity 75%
> at 1000mb:
>
> NCL: pot_temp_equiv = 69.1°C, 72.7°C, 76.4°C, 80.3°C, 84.3°C
> Bolton Eqn 39  = 77.8°C, 82.2°C, 86.9°C, 91.8°C, 97.0°C
>
> These are substantially different values for the warm pool.  This is
> important for researchers analyzing buoyancy differences for tropical
> disturbances.
>
> -Jonathan R. Buzan
>
>
>
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<http://www.cyclonecenter.org/>   *Carl J. Schreck III, PhD*
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