Potential artifacts in conservation laws and invariants inferred from sequential state estimation
<p>In sequential estimation methods often used in oceanic and general climate calculations of the state and of forecasts, observations act mathematically and statistically as source or sink terms in conservation equations for heat, salt, mass, and momentum. These artificial terms obscure the i...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-08-01
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| Series: | Ocean Science |
| Online Access: | https://os.copernicus.org/articles/19/1253/2023/os-19-1253-2023.pdf |
| Summary: | <p>In sequential estimation methods often used in oceanic and general climate
calculations of the state and of forecasts, observations act mathematically
and statistically as source or sink terms in conservation equations for heat, salt, mass, and momentum.
These artificial terms obscure the inference of the system's variability or secular changes.
Furthermore, for the purposes of calculating changes in
important functions of state variables such as total mass and energy or
volumetric current transports, results of both filter and smoother-based estimates are sensitive to misrepresentation
of a large variety of parameters, including initial conditions, prior
uncertainty covariances, and systematic and random errors in observations.
Here, toy models of a coupled mass–spring oscillator system and of a barotropic Rossby wave system are used to
demonstrate many of the issues that arise from such misrepresentations.
Results from Kalman filter estimates and those from finite interval
smoothing are analyzed.
In the filter (and prediction) problem, entry of data leads to violation of
conservation and other invariant rules.
A finite interval smoothing method restores the conservation rules, but
uncertainties in all such estimation results remain. Convincing trend and
other time-dependent determinations in “reanalysis-like” estimates require a full understanding of models, observations, and underlying error structures. Application of smoother-type methods that are designed for optimal reconstruction purposes alleviate some of the issues.</p> |
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| ISSN: | 1812-0784 1812-0792 |