Nudging and correction module

[timspainNERSC]

One currently unimplemented, but needed, module for nextSIM-DG is one that allow implementation of corrective fluxes or corrections to the prognostic fields. Uses cases would include

• Nudging fluxes for when data assimilation has removed sea ice, but the underlying modelled ocean surface is still cold enough to freeze
• Flux correction when running a low resolution model, using the rests derived from higher resolution runs.

Amongst the questions that need to be answered are:

• What kind of data sources does the interface class need to support?
  • Are there any, or can this all be handled by implementation code?
• What fields might need to be adjusted?
  • All prognostic fields?
  • A subset?
  • Some diagnostic fields?
• What fluxes should be supported?
  • Where do these fluxes need to be applied?