Diagonal observation error covariance (l95/QG/UFO)

The generic diagonal observation error covariance \(R\) implementation in OOPS has been removed and replaced with specific implementations where one is required (in the l95 and QG toy models, in UFO, and in some model interfaces). For the vast majority of use cases, the new generic diagonal \(R\) implmentation can be used instead and will exactly replicate the old OOPS implementation.

The old behavior of defaulting to a diagonal ObsError when not including an ObsError: has been preserved, and can still also be explicitly included as:

obs error:
  covariance model: diagonal

For EDA experiments, the obs perturbations amplitude setting remains in all implementations and can be included in the same format as before:

obs error:
  covariance model: diagonal
  obs perturbations amplitude: 0.5

Availability of the zero-mean perturbations feature for EDA is now implementation specific, but is available in the new generic diagonal observation error covariance in UFO. See Diagonal observation error covariance for more information.