John Ssebandeke, Jin-Song von Storch, Nils Brüggemann
{"title":"Sensitivity of the Lorenz energy cycle of the global ocean","authors":"John Ssebandeke, Jin-Song von Storch, Nils Brüggemann","doi":"10.1007/s10236-023-01568-6","DOIUrl":null,"url":null,"abstract":"Abstract We re-examine the Lorenz energy cycle (LEC) for the global ocean by assessing its sensitivity to model and forcing differences. We do so by comparing LECs derived from two simulations based on different eddy-rich ocean models, ICON-O and MPI-OM, both driven by NCEP/NCAR reanalysis, and by comparing LECs derived from two simulations generated using ICON-O model but driven by two different reanalyses, NCEP/NCAR and ERA5. Regarding model difference, we find weaker eddy kinetic energy, $$k_e$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>k</mml:mi> <mml:mi>e</mml:mi> </mml:msub> </mml:math> , in the ICON-O simulation than in the MPI-OM simulation. We attribute this to the higher horizontal resolution of MPI-OM in the Southern Ocean. The weaker $$k_e$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>k</mml:mi> <mml:mi>e</mml:mi> </mml:msub> </mml:math> in ICON-O is not caused by the lack of eddy available potential energy, $$p_e$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>p</mml:mi> <mml:mi>e</mml:mi> </mml:msub> </mml:math> , but by the strong dissipation of $$p_e$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>p</mml:mi> <mml:mi>e</mml:mi> </mml:msub> </mml:math> and the resulting weak conversion from $$p_e$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>p</mml:mi> <mml:mi>e</mml:mi> </mml:msub> </mml:math> to $$k_e$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>k</mml:mi> <mml:mi>e</mml:mi> </mml:msub> </mml:math> . Regarding forcing difference, we find that considerably more mechanical energy is generated by the ERA5 forcing, which has a higher spatial-temporal resolution compared to the NCEP/NCAR forcing. In particular, the generation of $$k_e$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>k</mml:mi> <mml:mi>e</mml:mi> </mml:msub> </mml:math> , which also contains the resolved part of the internal wave spectrum, is enhanced by about 1 TW (40%). However, the dominance of the baroclinic and the barotropic pathways forces the enhanced generation of $$k_e$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mi>k</mml:mi> <mml:mi>e</mml:mi> </mml:msub> </mml:math> to be balanced by an enhanced dissipation in the surface layer. The gross features of LEC are insensitive to both model and forcing differences, picturing the ocean as an inefficient “windmill” that converts only a small portion of the inputted mechanical energy into the interior mean and transient circulations.","PeriodicalId":19387,"journal":{"name":"Ocean Dynamics","volume":null,"pages":null},"PeriodicalIF":2.2000,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Ocean Dynamics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1007/s10236-023-01568-6","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"OCEANOGRAPHY","Score":null,"Total":0}
引用次数: 0
Abstract
Abstract We re-examine the Lorenz energy cycle (LEC) for the global ocean by assessing its sensitivity to model and forcing differences. We do so by comparing LECs derived from two simulations based on different eddy-rich ocean models, ICON-O and MPI-OM, both driven by NCEP/NCAR reanalysis, and by comparing LECs derived from two simulations generated using ICON-O model but driven by two different reanalyses, NCEP/NCAR and ERA5. Regarding model difference, we find weaker eddy kinetic energy, $$k_e$$ ke , in the ICON-O simulation than in the MPI-OM simulation. We attribute this to the higher horizontal resolution of MPI-OM in the Southern Ocean. The weaker $$k_e$$ ke in ICON-O is not caused by the lack of eddy available potential energy, $$p_e$$ pe , but by the strong dissipation of $$p_e$$ pe and the resulting weak conversion from $$p_e$$ pe to $$k_e$$ ke . Regarding forcing difference, we find that considerably more mechanical energy is generated by the ERA5 forcing, which has a higher spatial-temporal resolution compared to the NCEP/NCAR forcing. In particular, the generation of $$k_e$$ ke , which also contains the resolved part of the internal wave spectrum, is enhanced by about 1 TW (40%). However, the dominance of the baroclinic and the barotropic pathways forces the enhanced generation of $$k_e$$ ke to be balanced by an enhanced dissipation in the surface layer. The gross features of LEC are insensitive to both model and forcing differences, picturing the ocean as an inefficient “windmill” that converts only a small portion of the inputted mechanical energy into the interior mean and transient circulations.
通过评估全球海洋的洛伦兹能量循环对模式和强迫差异的敏感性,我们重新审视了全球海洋的洛伦兹能量循环。我们通过比较基于NCEP/NCAR再分析驱动的ICON-O和MPI-OM两种不同富涡海洋模型的模拟结果得出的LECs,以及通过比较由ICON-O模型生成但由NCEP/NCAR和ERA5两种不同再分析驱动的两个模拟结果得出的LECs。在模式差异方面,ICON-O模拟的涡动能$$k_e$$ ke比MPI-OM模拟的弱。我们将此归因于南大洋MPI-OM的水平分辨率较高。ICON-O中较弱的$$k_e$$ ke不是由于缺乏涡动有效势能$$p_e$$ p e造成的,而是由于$$p_e$$ p e的强耗散以及由此产生的从$$p_e$$ p e到$$k_e$$ ke的弱转换。在强迫差异方面,ERA5强迫产生的机械能明显高于NCEP/NCAR强迫,且具有更高的时空分辨率。特别是,$$k_e$$ k e的生成,也包含了内波谱的分解部分,增强了约1 TW (40)%). However, the dominance of the baroclinic and the barotropic pathways forces the enhanced generation of $$k_e$$ k e to be balanced by an enhanced dissipation in the surface layer. The gross features of LEC are insensitive to both model and forcing differences, picturing the ocean as an inefficient “windmill” that converts only a small portion of the inputted mechanical energy into the interior mean and transient circulations.
期刊介绍:
Ocean Dynamics is an international journal that aims to publish high-quality peer-reviewed articles in the following areas of research:
Theoretical oceanography (new theoretical concepts that further system understanding with a strong view to applicability for operational or monitoring purposes);
Computational oceanography (all aspects of ocean modeling and data analysis);
Observational oceanography (new techniques or systematic approaches in measuring oceanic variables, including all aspects of monitoring the state of the ocean);
Articles with an interdisciplinary character that encompass research in the fields of biological, chemical and physical oceanography are especially encouraged.