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Model parameters

Functions that can calculate the parameters required to run a Pitzer model from temperature and pressure are compiled into ParameterLibrarys, which can be imported from pytzer.libraries.

Parameter libraries

Import library

Import the ParameterLibrary that you wish to use with (e.g.):

from pytzer.libraries import Seawater

The options are:

  • Clegg22: CHW22
  • Clegg94: CRP94
  • Greenberg89: GM89
  • Harvie84: HMW84
  • Humphreys22: HWT22
  • MarChemSpec
  • MarChemSpec25
  • Millero98: MP98, a.k.a. MIAMI
  • Moller88: M88
  • Seawater
  • Waters13: WM13
  • Waters13_MarChemSpec25

Update unsymmetrical mixing function

Different ParameterLibrarys are designed for use with different J functions for unsymmetrical mixing. To change which function is being used throughout Pytzer, use (e.g.):

import pytzer as pz
from pytzer.libraries import Seawater

pz = Seawater.set_func_J(pz)

This step can be slow, as all the model functions must be recompiled afterwards. It only needs to be repeated if the ParameterLibrary being used is changed.

Evaluate parameters

To generate the params dict required for various functions in Pytzer, use (e.g.):

from pytzer.libraries import Seawater

params = Seawater.get_parameters(
    solutes=None, temperature=298.15, pressure=10.1023, verbose=True

The arguments are:

  • solutes: an OrderedDict where the keys represent the solutes in the solution, as described in the model arguments. If None, then parameters are evaluated for all solutes represented by the ParameterLibrary's functions.
  • temperature: in K.
  • pressure: in dbar.
  • verbose: do you want to print a warning to stdout whenever there is no function in the ParameterLibrary for any interaction between the solutes?

If you are running Pytzer over multiple different solutions, then you need to re-run get_parameters() between each solution only if the temperature, pressure, or combination of solutes has changed. In other words, if only the molality values for the solutes have changed between calculations, then you do not need to re-run get_parameters().