Reading data from one grid and adding the value of a cell to another grid

[lizadams]

Is your feature request related to a problem? Please describe.
The user would like to add a concentration value from one grid to another grid.

Describe the solution you'd like
(this request was from the CMAS Center Forum post: https://forum.cmascenter.org/t/reading-data-from-one-grid-and-adding-the-value-of-a-cell-to-another-grid/4768
I’m running CMAQ on two different grids, one coarse and one fine within the former one, but these are not nested and come from two different sets of simulations (one with wind blown dust and one without).
I wonder if I can evaluate the value of one variable at a specific cell of the coarse grid and add it to the data of all cells in the fine grid inside VERDI, by some kind of formula?
To be more specific (in VERDI environment), can I write a formula based on the value of a specific cell (or a probe)?
I think it’s quite doable outside VERDI, but I prefer to do it in VERDI, as it makes things much easier for me.
By the way, I’m working on VERDI 2.1.3.

Describe alternatives you've considered

Additional context