Future developments for stand-alone UKCA
- Can some of the `active' code be removed? Because it
- produces calculations we don't need, or
- could be parameterised
- Allow code to receive U, V, W, θ and q from a
concurrent code (in the future, our N216 code)
- Allow code to pass out green house gases and aerosol.
- Convective mass fluxes? Maybe keep in UKCA stand-alone.