Updated LUMIA uncertainty settings

[lumia-dev]

FYI, @vishnuthilakan, @Yohanna-Villalobos, @AugustThomasson, @cdgomezo:

I updated the master to include changes I did for my CH4 inversions, in order to create a new LUMIA release (https://github.com/lumia-dev/lumia/releases/tag/egusphere-2024-3122). It might have introduced some incompatibilities with your existing config files:

Emission uncertainties

There's now two options for the uncertainty structure:

• linear: the uncertainty of a state variable $\mathbf{x_i}$ is proportional to the sum of the absolute value of the emissions/fluxes controlled by that variable (e.g., if $\mathbf{x_i}$ is daily, but the fluxes are hourly, then $\mathbf{\varepsilon_{x_i}}$ will be proportional to the sum of the absolute value of the hourly fluxes. This was the normal LUMIA behaviour until now.
• file: the uncertainty structure is directly read from a file.

This needs to be set in the optimize.emissions.{tracer}.{category}.error_structure section of the YAML files:

optimize:
  emissions:
    tracer_XX:
      category_YY:
        error_structure:
          type: # Should be "linear" or "file"
          file: # Needed only if "type" is set to "file" (then it needs to be the path to the correlation file).
        annual_uncertainty:
        horizontal_correlation:
          type:
          correlation_length:
        temporal_correlation:
          type:
          correlation_length:
        optimization_interval:
      optim_scf: # optional, see section below

See https://github.com/lumia-dev/lumia/blob/master/run/egusphere-2024-3122/LUMIA-Lpri.yaml for a full example.

Optimization type

The standard so far in LUMIA is to solve for an offset to the prior emissions. There should now be the possibility to solve for a scaling factor instead. This is controlled by optimize.emissions.optim_scf. It's turned off by default, and it's not 100% tested.