2
$\begingroup$

I am using ERA5 data to drive the land surface model. One of the forcing required by LSM is specific humidity. We want to use the 2-m specific humidity. So how can I calculate the specific humidity based on dew point at 2 meters, surface pressure at 2 meters and temperature at 2 meters? I saw in ERA5 documentation we can calculate the 'saturated specific humidity' by some equations (https://confluence.ecmwf.int/display/CKB/ERA5%3A+data+documentation#ERA5:datadocumentation-Computationofnear-surfacehumidityandsnowcover). enter image description here But how can I get the specific humidity?

Thanks and hope for your early reply!

Improve this question
$\endgroup$
1
$\begingroup$

The answer is easy. Replace $T$ with $T_d$, where $T_d$ is the dewpoint temperature.

I will say I am not all that familiar with those equations, but that is besides the point.

Improve this answer
$\endgroup$
0
$\begingroup$

Just in case it will save a great deal of time for others in the future, ill recommend the metpy package.

https://unidata.github.io/MetPy/latest/api/generated/metpy.calc.specific_humidity_from_dewpoint.html

Improve this answer
$\endgroup$
2
  • 1
    $\begingroup$ Please expand the answer to detail the specifics of the package $\endgroup$
    – arkaia
    Jun 5 at 12:20
  • $\begingroup$ The specifics are detailed in the link. In summary, it's a python function that requires the surface pressure and the dew point temperature and computes the specific humidity from these two variables. $\endgroup$
    – innomask
    Jun 5 at 13:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.