Is it possible to do complete Moisture budget analysis using MetPy ?

[AniIlyich]

Hi there,
I am currently working on project in which I have to do the moisture budget analysis in the atmosphere, for which I have to calculate the vertically integrated moisture advection ⟨ω 𝜕q𝜕p ⟩ and vertically integrated horizontal moisture advection term −⟨V ̄ ⋅ ∇ q⟩.
I believe that the horizontal advection can be calculated using MetPy's advection function, I was wondering how can I calculate the vertical advection of moisture in isobaric coordinates ( where I ω is the pressure velocity and q specific humidity)
Thanks !
(refer for terms : https://doi.org/10.1007/s00382-018-4394-x )

[dopplershift]

Provided you have q on pressure levels, you should be able to calculate vertical advection with:

import metpy.calc as mpcalc
vert_adv = mpcalc.advection(q, w=omega)

[AniIlyich]

@dopplershift Thanks for the reply this was very helpfull.

[AniIlyich]

@dopplershift On a side note, is it possible to calculate vertical gradient and divergence also using Metpy function like this, If yes I was curios to know how dp is determined ?

[dopplershift]

If you're only worried about a single direction, you don't need to bother with gradient, just use first_derivative, which can handle discrete data with arbitrary spacing. (I'm not sure "divergence" has any meaning given a single component.)

first_derivative is going to calculate using either the attached vertical coordinate information (when given an xarray DataArray), or rely on what is passed in as x). This means you either already have data on isobaric coordinates, or you'll need to make the effort to convert data in height coordinates to isobaric ones--otherwise first_derivative will be producing d/dz.

[AniIlyich]

Great, Thanks a lot @dopplershift

[nora-fahrenbach]

@AniIlyich Hi there, your post has been a while ago but I am working on a somewhat similar problem now. The moisture decomposition I want to do is similar to the one in Seager et al 2010 (Eq. 4-7), including to calculate the thermodynamic, mean circulation dynamic and transient eddy term. Did you by any chance do a full moisture decomposition in the end using MetPy?

[AniIlyich]

@nora-fahrenbach Hi there, What I ended up doing was separately finding each term using the first_derivative and adding to complete the equation.