earthkit.meteo.thermo.fieldlist.saturation_ept

earthkit.meteo.thermo.fieldlist.saturation_ept(t, p=None, method='ifs')

Compute the saturation equivalent potential temperature.

Parameters:

• t (FieldList|Field) – Temperature (K).

• p (FieldList|Field|Iterable[float]|float|None) – Pressure (Pa). If None, inferred from the field metadata of t. Otherwise, if t is a FieldList p must be a FieldList or an array-like of the same length as t. If t is a Field, p must be a single Field or a float.

• method (str, optional) – Specifies the computation method. The possible values are: “ifs”, “bolton35”, “bolton39”.

Returns:

Saturation equivalent potential temperature (K). The result has the same type as the input t (FieldList or Field).

Return type:

FieldList|Field

The actual computation is based on the method:

• “ifs”: The formula is based on the equivalent potential temperature definition used

  in the IFS model [IFS-CY47R3-PhysicalProcesses] (see Chapter 6.11) :

  \[\Theta_{esat} = \Theta exp(\frac{L_{v} q_{sat}}{c_{pd} t})\]

• “bolton35”: Eq (35) from [Bolton1980] is used:

  \[\Theta_{e} = \Theta (\frac{10^{5}}{p})^{\kappa 0.28 w_{sat}} exp(\frac{2675 w_{sat}}{t})\]

• “bolton39”: Eq (39) from [Bolton1980] is used:

  \[\Theta_{e} = t (\frac{10^{5}}{p-e_{sat}})^{\kappa} exp[(\frac{3036}{t} - 1.78)w_{sat}(1+0.448 w_{sat})]\]

where:

• \(\Theta\) is the potential_temperature()

• \(e_{sat}\) is the saturation_vapor_pressure()

• \(q_{sat}\) is the saturation_specific_humidity()

• \(w_{sat}\) is the saturation_mixing_ratio()

• \(L_{v}\) is the specific latent heat of vaporization (see earthkit.meteo.constants.Lv)

• \(c_{pd}\) is the specific heat of dry air on constant pressure (see earthkit.meteo.constants.c_pd)