Articles | Volume 19, issue 4
https://doi.org/10.5194/os-19-1253-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-19-1253-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Potential artifacts in conservation laws and invariants inferred from sequential state estimation
Carl Wunsch
Department of Earth and Planetary Science, Harvard University, Cambridge, MA, USA
Oden Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, USA
Patrick Heimbach
Oden Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, USA
Jackson School of Geosciences, University of Texas at Austin, Austin, TX, USA
Institute for Geophysics, University of Texas at Austin, Austin, TX, USA
Related authors
Carl Wunsch
Ocean Sci. Discuss., https://doi.org/10.5194/os-2021-113, https://doi.org/10.5194/os-2021-113, 2021
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Combinations of observations with dynamical, chemical, etc, models are essential tools for understanding of climate change. By "climate" is meant all of the sub-elements including ocean, atmosphere, ice, et al. A common form of combination arises from sequential estimation theory, a methodology susceptible to a variety of errors that can accumulate through time for long records. Using two simple analogues, many of these errors are identified here, with suggestions for accommodating them.
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This paper examines the oxygen isotope data in several deep-sea cores. The question addressed is whether those data support an inference that the abyssal ocean in the Last Glacial Maximum period was significantly colder than it is today. Along with a separate analysis of salinity data in the same cores, it is concluded that a cold, saline deep ocean is consistent with the available data but so is an abyss much more like that found today. LGM model testers should beware.
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Numerical ocean forecasting is a key part of accurate models of the earth system. However, they require powerful computing resources and the architectures of the necessary computers are evolving rapidly. Unfortunately, this is a disruptive change – an ocean model must be modified to enable it to make use of this new computing hardware. This paper reviews what has been done in this area and identifies solutions to enable operational ocean forecasts to make use of the new computing hardware.
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Operational ocean prediction relies on computationally expensive numerical models and complex workflows known as data assimilation, in which models are fit to observations to produce optimal initial conditions for prediction. Machine learning has the potential to vastly accelerate ocean prediction, improve uncertainty quantification through massive surrogate model-based ensembles, and render simulations more accurate through better model calibration. We review developments and challenges.
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Carl Wunsch
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Preprint withdrawn
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Combinations of observations with dynamical, chemical, etc, models are essential tools for understanding of climate change. By "climate" is meant all of the sub-elements including ocean, atmosphere, ice, et al. A common form of combination arises from sequential estimation theory, a methodology susceptible to a variety of errors that can accumulate through time for long records. Using two simple analogues, many of these errors are identified here, with suggestions for accommodating them.
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Nat Wilson, Fiammetta Straneo, and Patrick Heimbach
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We estimate submarine melt rates from ice tongues in northern Greenland using WorldView satellite imagery. At Ryder Glacier, melt is strongly concentrated around regions where subglacier channels likely enter the fjord. At the 79 North Glacier, we find a large volume imbalance in which melting removes a greater quantity of ice than is replaced by inflow over the grounding line. This leads us to suggest that a reduction in the spatial extent of the ice tongue is possible over the coming decade.
Carl Wunsch
Clim. Past, 12, 1281–1296, https://doi.org/10.5194/cp-12-1281-2016, https://doi.org/10.5194/cp-12-1281-2016, 2016
Short summary
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This paper examines the oxygen isotope data in several deep-sea cores. The question addressed is whether those data support an inference that the abyssal ocean in the Last Glacial Maximum period was significantly colder than it is today. Along with a separate analysis of salinity data in the same cores, it is concluded that a cold, saline deep ocean is consistent with the available data but so is an abyss much more like that found today. LGM model testers should beware.
G. Forget, J.-M. Campin, P. Heimbach, C. N. Hill, R. M. Ponte, and C. Wunsch
Geosci. Model Dev., 8, 3071–3104, https://doi.org/10.5194/gmd-8-3071-2015, https://doi.org/10.5194/gmd-8-3071-2015, 2015
Short summary
Short summary
The ECCO v4 non-linear inverse modeling framework and its reference solution are made publicly available. The inverse estimate of ocean physics and atmospheric forcing yields a dynamically consistent and global state estimate without unidentified sources of heat and salt that closely fits in situ and satellite data. Any user can reproduce it accurately. Parametric and external model uncertainties are of comparable magnitudes and generally exceed structural model uncertainties.
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Short summary
Data assimilation methods that couple observations with dynamical models are essential for understanding climate change. Here,
climateincludes all sub-elements (ocean, atmosphere, ice, etc.). A common form of combination arises from sequential estimation theory, a methodology susceptible to a variety of errors that can accumulate through time for long records. Using two simple analogs, examples of these errors are identified and discussed, along with suggestions for accommodating them.
Data assimilation methods that couple observations with dynamical models are essential for...