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[python #JDP-816316]: Pseudo-adiabatic parameters with ice processes

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  • Subject: [python #JDP-816316]: Pseudo-adiabatic parameters with ice processes
  • Date: Wed, 10 May 2023 14:27:10 -0600
Hello, and thanks for reaching out!

MetPy's parcel calculations depend on 
`moist_lapse`(https://unidata.github.io/MetPy/latest/api/generated/metpy.calc.moist_lapse.html),
 which uses a saturated pseudoadiabatic process (aka "moist adiabat"), 
described in Section 1b of Bakshaii and Stull 2013 
(https://journals.ametsoc.org/view/journals/apme/52/1/jamc-d-12-062.1.xml). 
Similarly, calculations of stability and moisture quantities rely on saturation 
vapor pressure 
(https://unidata.github.io/MetPy/latest/api/generated/metpy.calc.saturation_vapor_pressure.html)
 assumptions to be over water.

These functions don't currently support specifying different processes or 
assumptions. There are ongoing discussions on GitHub about enabling alternative 
calculations, processes, and thermodynamic assumptions:

  https://github.com/Unidata/MetPy/issues/434
  https://github.com/Unidata/MetPy/issues/461
  https://github.com/Unidata/MetPy/issues/142

There have been movements on these issues recently, including adopting the 
usage of virtual temperature in CAPE/CIN calculations. We welcome community 
input and contributions here! I hope this helps, and please do follow up if we 
can answer any additional questions.


All the best,

Drew


> I'm looking to gain some clarity on the adiabatic processes used in the
> following Metpy functions:
> 
> 1. metpy.calc.parcel_profile
> 2. metpy.calc.cape_cin
> 3. metpy.calc.most_unstable_parcel
> 4. metpy.calc.most_unstable_cape_cin
> 
> Is the default process pseudo-adiabatic with liquid only, reversible with
> liquid only, pseudo-adiabatic with ice, or reversible with ice for those 4
> functions? Do these functions have the capacity to specify which adiabatic
> process to use?
> 
> I've looked through some of the online documentation but haven't found
> explicit mention of adiabatic process information (however, if I missed
> this, please point me in the right direction!).
> 


Ticket Details
===================
Ticket ID: JDP-816316
Department: Support Python
Priority: Low
Status: Closed
===================
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