earthkit.meteo.thermo.xarray.dewpoint_from_specific_humidity

earthkit.meteo.thermo.xarray.dewpoint_from_specific_humidity(q, p)

Compute the dewpoint temperature from specific humidity.

Parameters:

• q (xarray.DataArray) – Specific humidity (kg/kg)

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

Returns:

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

Return type:

xarray.DataArray

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().