Irrotational/Non-Divergent Wind Computation

[jsillin]

It would be nice to have functions that return the irrotational and non-divergent components of a given wind field (in u and v form). These quantities have many applications in meteorology, including in the analysis of tropical cyclones, extratropical lows, and larger Rossby Wave dynamics (among I'm sure many others).

So input is a gridded u and v wind field and output is a gridded u and v irrotational wind field or a gridded u and v non-divergent wind field.

NCL has a function that does this

It looks like someone has done a version of this for python but apparently it only works with global data and not regional data as per this twitter thread.

As far as a scholarly reference for how exactly to do this, the best I could find after searching for a few minutes seems to be Shukla and Saha (1974).

I am very far from an expert on the math behind irrotational and non-divergent wind computations, and have never done a feature request like this before so I apologize if I have left out some important information somewhere along the way!

[dopplershift]

@jsillin Thanks for all the info in the feature request, this is great.

[ktyle]

The windspharm project (last updated in 2018) might be a good resource ... I've used it on global (but not regional) grids.