Observation Errors in UFO

UFO provides many ways of specifying observation uncertainites (also known as observation errors). Below is an outline of options:

• Using filters to specify observation uncertainties
  • GNSS-RO observation uncertainties
• Observation error covariances in UFO
  • Observation error covariance with cross-variable (cross-channel) correlations
  • Diagonal observation error covariance
  • Correlated Observation Error Covariance with Diffusion
  • Observation error covariance with correlations for observations within one record
  • Specifying observation error standard deviations

Some observation error operators have reconditioning options for cases in which the operator may not be positive definite (which can cause instabilities when inverting the operator). For more information see:

• Obs Error Reconditioning
  • Ridge Regression
  • Minimum Eigenvalue