earthkit.meteo.thermo.dewpoint_from_specific_humidity

earthkit.meteo.thermo.dewpoint_from_specific_humidity(q: ArrayLike, p: ArrayLike) → ArrayLike

earthkit.meteo.thermo.dewpoint_from_specific_humidity(q: xarray.DataArray, p: xarray.DataArray) → xarray.DataArray

earthkit.meteo.thermo.dewpoint_from_specific_humidity(q: earthkit.data.FieldList, p: earthkit.data.FieldList) → earthkit.data.FieldList

Compute the dewpoint temperature from specific humidity.

Parameters:

• q (array-like) – Specific humidity (kg/kg)

• p (array-like) – Pressure (Pa)

Returns:

Dewpoint temperature (K). For zero q values returns nan.

Return type:

array-like

The computation starts with determining the the saturation vapour pressure over water at the dewpoint temperature:

\[e_{wsat}(td) = e(q, p)\]

where:

• \(e\) is the vapour pressure (see vapour_pressure_from_specific_humidity())

• \(e_{wsat}\) is the saturation_vapour_pressure() over water

• \(td\) is the dewpoint

Then \(td\) is computed from \(e_{wsat}(td)\) by inverting the equations used in saturation_vapour_pressure().

Implementations

dewpoint_from_specific_humidity() calls one of the following implementations depending on the type of the input arguments:

• earthkit.meteo.thermo.array.dewpoint_from_specific_humidity() for array-like

• earthkit.meteo.thermo.xarray.dewpoint_from_specific_humidity() for xarray.DataArray

• earthkit.meteo.thermo.fieldlist.dewpoint_from_specific_humidity() for FieldList

The function returns an object of the same type as the input arguments.