earthkit.meteo.thermo.xarray.wet_bulb_potential_temperature_from_dewpoint

earthkit.meteo.thermo.xarray.wet_bulb_potential_temperature_from_dewpoint(t, td, p, ept_method='ifs', t_method='direct')

Compute the pseudo adiabatic wet bulb potential temperature from dewpoint.

Parameters:

• t (xarray.DataArray) – Temperature (K)

• td (xarray.DataArray) – Dewpoint (K)

• p (xarray.DataArray) – Pressure (Pa)

• ept_method (str, optional) – Specifies the computation method for the equivalent potential temperature. The possible values are: “ifs”, “bolton35”, “bolton39”. (See ept_from_dewpoint() for details.)

• t_method (str, optional) –

  Specifies the method to find the temperature along the moist adiabat defined by the equivalent potential temperature. The possible values are as follows:

  • ”direct”: the rational formula defined by Eq (3.8) in [DaviesJones2008] is used

  • ”bisect”: temperature_on_moist_adiabat() with t_method = “bisect” is used

  • ”newton”: temperature_on_moist_adiabat() with t_method = “newton” is used

Returns:

Wet bulb potential temperature (K)

Return type:

xarray.DataArray

The computation is based on Normand’s rule [Wallace2006] (Chapter 3.5.6):

• first the equivalent potential temperature is computed with the given ept_method (using ept_from_dewpoint()). This defines the moist adiabat.

• then the wet bulb potential temperature is determined as the temperature at pressure \(10^{5}\) Pa on the moist adiabat with the given t_method.