specific_humidity_from_dewpoint
- specific_humidity_from_dewpoint(td[, p])
New in Metview version 5.13.0.
Computes the specific humidity from the given dewpoint (
td
) and pressure (p
).- Parameters
- Return type
same type as
td
or None
The result is the specific humidity in kg/kg units. On error None is returned. The following rules are applied when
td
is aFieldset
:if
td
is a pressure levelFieldset
nop
is neededif
td
is defined on ECMWF model levels (hybrid/eta)p
must be either a single LNSP (logarithm of surface pressure, identified by paramId=152) field or aFieldset
defining the pressure on the same levels astd
for other level types
p
must be aFieldset
defining the pressure on the same levels astd
When the result is a
Fieldset
the ecCodes paramId in the output is set to 133 (=specific humidity).The computation is based on the following equation:
\[e(q, p) = e_{wsat}(td)\]- where:
e is the vapour pressure (see
vapour_pressure()
)ewsat is the saturation vapour pressure over water (see
saturation_vapour_pressure()
)td is the dewpoint temperature