The interpretation of temperature and salinity variables in numerical ocean model output and the calculation of heat fluxes and heat content
The international Thermodynamic Equation of Seawater 2010 (TEOS-10) defined the enthalpy and entropy of seawater, thus enabling the global ocean heat content to be calculated as the volume integral of the product of in situ density, ρ, and potential enthalpy, h 0 (with reference sea pressure of 0 db...
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ftosti:oai:osti.gov:1829584 2023-07-30T04:06:48+02:00 The interpretation of temperature and salinity variables in numerical ocean model output and the calculation of heat fluxes and heat content None, None 2021-12-17 application/pdf http://www.osti.gov/servlets/purl/1829584 https://www.osti.gov/biblio/1829584 https://doi.org/10.5194/gmd-14-6445-2021 unknown http://www.osti.gov/servlets/purl/1829584 https://www.osti.gov/biblio/1829584 https://doi.org/10.5194/gmd-14-6445-2021 doi:10.5194/gmd-14-6445-2021 54 ENVIRONMENTAL SCIENCES 2021 ftosti https://doi.org/10.5194/gmd-14-6445-2021 2023-07-11T10:08:10Z The international Thermodynamic Equation of Seawater 2010 (TEOS-10) defined the enthalpy and entropy of seawater, thus enabling the global ocean heat content to be calculated as the volume integral of the product of in situ density, ρ, and potential enthalpy, h 0 (with reference sea pressure of 0 dbar). In terms of Conservative Temperature, Θ, ocean heat content is the volume integral of $ρc^0_p$Θ, where c$^0_p$ is a constant “isobaric heat capacity”. However, many ocean models in the Coupled Model Intercomparison Project Phase 6 (CMIP6) as well as all models that contributed to earlier phases, such as CMIP5, CMIP3, CMIP2, and CMIP1, used EOS-80 (Equation of State – 1980) rather than the updated TEOS-10, so the question arises of how the salinity and temperature variables in these models should be physically interpreted, with a particular focus on comparison to TEOS-10-compliant observations. In this article we address how heat content, surface heat fluxes, and the meridional heat transport are best calculated using output from these models and how these quantities should be compared with those calculated from corresponding observations. We conclude that even though a model uses the EOS-80, which expects potential temperature as its input temperature, the most appropriate interpretation of the model's temperature variable is actually Conservative Temperature. This perhaps unexpected interpretation is needed to ensure that the air–sea heat flux that leaves and arrives in atmosphere and sea ice models is the same as that which arrives in and leaves the ocean model. We also show that the salinity variable carried by present TEOS-10-based models is Preformed Salinity, while the salinity variable of EOS-80-based models is also proportional to Preformed Salinity. These interpretations of the salinity and temperature variables in ocean models are an update on the comprehensive Griffies et al. (2016) paper that discusses the interpretation of many aspects of coupled Earth system models. Other/Unknown Material Sea ice SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) Geoscientific Model Development 14 10 6445 6466 |
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SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
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54 ENVIRONMENTAL SCIENCES |
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54 ENVIRONMENTAL SCIENCES None, None The interpretation of temperature and salinity variables in numerical ocean model output and the calculation of heat fluxes and heat content |
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54 ENVIRONMENTAL SCIENCES |
description |
The international Thermodynamic Equation of Seawater 2010 (TEOS-10) defined the enthalpy and entropy of seawater, thus enabling the global ocean heat content to be calculated as the volume integral of the product of in situ density, ρ, and potential enthalpy, h 0 (with reference sea pressure of 0 dbar). In terms of Conservative Temperature, Θ, ocean heat content is the volume integral of $ρc^0_p$Θ, where c$^0_p$ is a constant “isobaric heat capacity”. However, many ocean models in the Coupled Model Intercomparison Project Phase 6 (CMIP6) as well as all models that contributed to earlier phases, such as CMIP5, CMIP3, CMIP2, and CMIP1, used EOS-80 (Equation of State – 1980) rather than the updated TEOS-10, so the question arises of how the salinity and temperature variables in these models should be physically interpreted, with a particular focus on comparison to TEOS-10-compliant observations. In this article we address how heat content, surface heat fluxes, and the meridional heat transport are best calculated using output from these models and how these quantities should be compared with those calculated from corresponding observations. We conclude that even though a model uses the EOS-80, which expects potential temperature as its input temperature, the most appropriate interpretation of the model's temperature variable is actually Conservative Temperature. This perhaps unexpected interpretation is needed to ensure that the air–sea heat flux that leaves and arrives in atmosphere and sea ice models is the same as that which arrives in and leaves the ocean model. We also show that the salinity variable carried by present TEOS-10-based models is Preformed Salinity, while the salinity variable of EOS-80-based models is also proportional to Preformed Salinity. These interpretations of the salinity and temperature variables in ocean models are an update on the comprehensive Griffies et al. (2016) paper that discusses the interpretation of many aspects of coupled Earth system models. |
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None, None |
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title |
The interpretation of temperature and salinity variables in numerical ocean model output and the calculation of heat fluxes and heat content |
title_short |
The interpretation of temperature and salinity variables in numerical ocean model output and the calculation of heat fluxes and heat content |
title_full |
The interpretation of temperature and salinity variables in numerical ocean model output and the calculation of heat fluxes and heat content |
title_fullStr |
The interpretation of temperature and salinity variables in numerical ocean model output and the calculation of heat fluxes and heat content |
title_full_unstemmed |
The interpretation of temperature and salinity variables in numerical ocean model output and the calculation of heat fluxes and heat content |
title_sort |
interpretation of temperature and salinity variables in numerical ocean model output and the calculation of heat fluxes and heat content |
publishDate |
2021 |
url |
http://www.osti.gov/servlets/purl/1829584 https://www.osti.gov/biblio/1829584 https://doi.org/10.5194/gmd-14-6445-2021 |
genre |
Sea ice |
genre_facet |
Sea ice |
op_relation |
http://www.osti.gov/servlets/purl/1829584 https://www.osti.gov/biblio/1829584 https://doi.org/10.5194/gmd-14-6445-2021 doi:10.5194/gmd-14-6445-2021 |
op_doi |
https://doi.org/10.5194/gmd-14-6445-2021 |
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Geoscientific Model Development |
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14 |
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6445 |
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6466 |
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