Water Mass Transformation Budgets in Finite‐Volume Generalized Vertical Coordinate Ocean Models
Abstract Water Mass Transformation (WMT) theory provides conceptual tools that in principle enable innovative analyses of numerical ocean models; in practice, however, these methods can be challenging to implement and interpret, and therefore remain under‐utilized. Our aim is to demonstrate the feas...
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American Geophysical Union (AGU)
2025-03-01
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| Series: | Journal of Advances in Modeling Earth Systems |
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| Online Access: | https://doi.org/10.1029/2024MS004383 |
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| author | Henri F. Drake Shanice Bailey Raphael Dussin Stephen M. Griffies John Krasting Graeme MacGilchrist Geoffrey Stanley Jan‐Erik Tesdal Jan D. Zika |
| author_facet | Henri F. Drake Shanice Bailey Raphael Dussin Stephen M. Griffies John Krasting Graeme MacGilchrist Geoffrey Stanley Jan‐Erik Tesdal Jan D. Zika |
| author_sort | Henri F. Drake |
| collection | DOAJ |
| description | Abstract Water Mass Transformation (WMT) theory provides conceptual tools that in principle enable innovative analyses of numerical ocean models; in practice, however, these methods can be challenging to implement and interpret, and therefore remain under‐utilized. Our aim is to demonstrate the feasibility of diagnosing all terms in the water mass budget and to exemplify their usefulness for scientific inquiry and model development by quantitatively relating water mass changes, overturning circulations, boundary fluxes, and interior mixing. We begin with a pedagogical derivation of key results of classical WMT theory. We then describe best practices for diagnosing each of the water mass budget terms from the output of Finite‐Volume Generalized Vertical Coordinate (FV‐GVC) ocean models, including the identification of a non‐negligible remainder term as the spurious numerical mixing due to advection scheme discretization errors. We illustrate key aspects of the methodology through the analysis of a polygonal region of the Greater Baltic Sea in a regional demonstration simulation using the Modular Ocean Model v6 (MOM6). We verify the convergence of our WMT diagnostics by brute‐force, comparing time‐averaged (“offline”) diagnostics on various vertical grids to timestep‐averaged (“online”) diagnostics on the native model grid. Finally, we briefly describe a stack of xarray‐enabled Python packages for evaluating WMT budgets in FV‐GVC models (culminating in the new xwmb package), which is intended to be model‐agnostic and available for community use and development. |
| format | Article |
| id | doaj-art-0ab53fd00a1e4d58ba6e3ba688e6ca2b |
| institution | DOAJ |
| issn | 1942-2466 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | American Geophysical Union (AGU) |
| record_format | Article |
| series | Journal of Advances in Modeling Earth Systems |
| spelling | doaj-art-0ab53fd00a1e4d58ba6e3ba688e6ca2b2025-08-20T02:54:12ZengAmerican Geophysical Union (AGU)Journal of Advances in Modeling Earth Systems1942-24662025-03-01173n/an/a10.1029/2024MS004383Water Mass Transformation Budgets in Finite‐Volume Generalized Vertical Coordinate Ocean ModelsHenri F. Drake0Shanice Bailey1Raphael Dussin2Stephen M. Griffies3John Krasting4Graeme MacGilchrist5Geoffrey Stanley6Jan‐Erik Tesdal7Jan D. Zika8Department of Earth System Science University of California Irvine Irvine CA USADepartment of Earth and Environmental Sciences Columbia University New York NY USAUniversity Corporation for Atmospheric Research Boulder CO USANOAA Geophysical Fluid Dynamics Laboratory Princeton NJ USANOAA Geophysical Fluid Dynamics Laboratory Princeton NJ USASchool of Earth and Environmental Sciences University of St. Andrews Saint Andrews UKCanadian Centre for Climate Modelling and Analysis Environment and Climate Change Canada Victoria BC CanadaPrinceton University Program in Atmospheric and Oceanic Sciences Princeton NJ USASchool of Mathematics and Statistics University of New South Wales Kensington NSW AustraliaAbstract Water Mass Transformation (WMT) theory provides conceptual tools that in principle enable innovative analyses of numerical ocean models; in practice, however, these methods can be challenging to implement and interpret, and therefore remain under‐utilized. Our aim is to demonstrate the feasibility of diagnosing all terms in the water mass budget and to exemplify their usefulness for scientific inquiry and model development by quantitatively relating water mass changes, overturning circulations, boundary fluxes, and interior mixing. We begin with a pedagogical derivation of key results of classical WMT theory. We then describe best practices for diagnosing each of the water mass budget terms from the output of Finite‐Volume Generalized Vertical Coordinate (FV‐GVC) ocean models, including the identification of a non‐negligible remainder term as the spurious numerical mixing due to advection scheme discretization errors. We illustrate key aspects of the methodology through the analysis of a polygonal region of the Greater Baltic Sea in a regional demonstration simulation using the Modular Ocean Model v6 (MOM6). We verify the convergence of our WMT diagnostics by brute‐force, comparing time‐averaged (“offline”) diagnostics on various vertical grids to timestep‐averaged (“online”) diagnostics on the native model grid. Finally, we briefly describe a stack of xarray‐enabled Python packages for evaluating WMT budgets in FV‐GVC models (culminating in the new xwmb package), which is intended to be model‐agnostic and available for community use and development.https://doi.org/10.1029/2024MS004383water mass transformationspurious numerical mixingocean mixingocean modelingdiapycnal mixing |
| spellingShingle | Henri F. Drake Shanice Bailey Raphael Dussin Stephen M. Griffies John Krasting Graeme MacGilchrist Geoffrey Stanley Jan‐Erik Tesdal Jan D. Zika Water Mass Transformation Budgets in Finite‐Volume Generalized Vertical Coordinate Ocean Models Journal of Advances in Modeling Earth Systems water mass transformation spurious numerical mixing ocean mixing ocean modeling diapycnal mixing |
| title | Water Mass Transformation Budgets in Finite‐Volume Generalized Vertical Coordinate Ocean Models |
| title_full | Water Mass Transformation Budgets in Finite‐Volume Generalized Vertical Coordinate Ocean Models |
| title_fullStr | Water Mass Transformation Budgets in Finite‐Volume Generalized Vertical Coordinate Ocean Models |
| title_full_unstemmed | Water Mass Transformation Budgets in Finite‐Volume Generalized Vertical Coordinate Ocean Models |
| title_short | Water Mass Transformation Budgets in Finite‐Volume Generalized Vertical Coordinate Ocean Models |
| title_sort | water mass transformation budgets in finite volume generalized vertical coordinate ocean models |
| topic | water mass transformation spurious numerical mixing ocean mixing ocean modeling diapycnal mixing |
| url | https://doi.org/10.1029/2024MS004383 |
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