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13. Parameterized Internal Wave Mixing in Three Ocean General Circulation Models.

Author

Brüggemann, Nils, Losch, Martin, Scholz, Patrick, Pollmann, Friederike, Danilov, Sergey, Gutjahr, Oliver, Jungclaus, Johann, Koldunov, Nikolay, Korn, Peter, Olbers, Dirk, and Eden, Carsten

Subjects
INTERNAL waves, GENERAL circulation model, OCEAN circulation, OCEANIC mixing, ATLANTIC meridional overturning circulation, OCEAN, TIDAL power, ROGUE waves
Abstract

The non‐local model of mixing based on internal wave breaking, IDEMIX, is implemented as an enhancement of a turbulent kinetic energy closure model in three non‐eddy resolving general circulation ocean models that differ in the discretization and choice of computational grids. In IDEMIX internal wave energy is generated by an energy flux resulting from near‐inertial waves induced by wind forcing at the surface, and at the bottom, by an energy flux that parameterizes the transfer of energy between baroclinic and barotropic tides. In all model simulations with IDEMIX, the mixing work is increased compared to the reference solutions without IDEMIX, reaching values in better agreement with finestructure observations. Furthermore, the horizontal structure of the mixing work is more realistic as a consequence of the heterogeneous forcing functions. All models with IDEMIX simulate deeper thermocline depths related to stronger shallow overturning cells in the Indo‐Pacific. In the North Atlantic, deeper mixed layers in simulations with IDEMIX are associated with an increased Atlantic overturning circulation and an increase of northward heat transports toward more realistic values. The response of the deep Indo‐Pacific overturning circulation and the weak bottom cell of the Atlantic to the inclusion of IDEMIX is incoherent between the models, suggesting that additional unidentified processes and numerical mixing may confound the analysis. Applying different tidal forcing functions leads to simulation differences that are small compared to differences between the different models or between simulations with IDEMIX and without IDEMIX. Plain Language Summary: Waves in the ocean interior play a fundamental role for ocean dynamics since they can carry energy over long distances and, once they break, lead to turbulent mixing. This turbulent mixing can cause dense water masses to rise from the deep ocean with a direct impact on large‐scale currents. The wave dynamics occur on spatial scales that cannot be resolved in global ocean or climate models. To account for these processes, we apply the new parameterization IDEMIX that describes internal wave generation, propagation, and mixing. Using three different ocean models with and without IDEMIX ensures that we can identify model‐specific effects of the parameterization and discriminate them from those independent of the model. We find that the simulated mixing patterns agree better with observations once IDEMIX is applied. Large‐scale currents and the vertical temperature distribution are substantially affected by the internal wave parameterization. Whether this leads to an improved agreement with observed currents and water mass properties depends on the specific model and on numerical effects. In most cases, simulations with IDEMIX are not very sensitive to details of how the internal wave model is driven by tidal energy input. Key Points: the IDEMIX closure for a consistent representation of internal wave‐induced mixing is evaluated in three state‐of‐the‐art ocean modelsonly in simulations with IDEMIX can the models reproduce the magnitude and spatial variability of the observed mixing workmost changes with IDEMIX can be attributed to stronger mixing, but some effects are confounded by other processes and numerical mixing [ABSTRACT FROM AUTHOR]

Published
2024
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14. First comprehensive assessment of industrial era land heat uptake from multiple sources

Author

García-Pereira, Félix, primary, González-Rouco, Jesús Fidel, additional, Melo-Aguilar, Camilo, additional, Steinert, Norman Julius, additional, García-Bustamante, Elena, additional, de Vrese, Philip, additional, Jungclaus, Johann, additional, Lorenz, Stephan, additional, Hagemann, Stefan, additional, Cuesta-Valero, Francisco José, additional, García-García, Almudena, additional, and Beltrami, Hugo, additional

Published
2024
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15. High-resolution marine data and transient simulations support orbital forcing of ENSO amplitude since the mid-Holocene

Author

Carré, Matthieu, Braconnot, Pascale, Elliot, Mary, d’Agostino, Roberta, Schurer, Andrew, Shi, Xiaoxu, Marti, Olivier, Lohmann, Gerrit, Jungclaus, Johann, Cheddadi, Rachid, Abdelkader di Carlo, Isma, Cardich, Jorge, Ochoa, Diana, Salas Gismondi, Rodolfo, Pérez, Alexander, Romero, Pedro E., Turcq, Bruno, Corrège, Thierry, and Harrison, Sandy P.

Published
2021
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19. What causes the spread of model projections of ocean dynamic sea-level change in response to greenhouse gas forcing?

Author

Couldrey, Matthew P., Gregory, Jonathan M., Boeira Dias, Fabio, Dobrohotoff, Peter, Domingues, Catia M., Garuba, Oluwayemi, Griffies, Stephen M., Haak, Helmuth, Hu, Aixue, Ishii, Masayoshi, Jungclaus, Johann, Köhl, Armin, Marsland, Simon J., Ojha, Sayantani, Saenko, Oleg A., Savita, Abhishek, Shao, Andrew, Stammer, Detlef, Suzuki, Tatsuo, Todd, Alexander, and Zanna, Laure

Published
2021
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21. A frequency-optimised temperature record for the Holocene

Author

Essell, Helen, primary, Krusic, Paul J, additional, Esper, Jan, additional, Wagner, Sebastian, additional, Braconnot, Pascale, additional, Jungclaus, Johann, additional, Muschitiello, Francesco, additional, Oppenheimer, Clive, additional, and Büntgen, Ulf, additional

Published
2023
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24. First comprehensive assessment of industrial era land heat uptake from multiple sources.

Author

García-Pereira, Félix, González-Rouco, Jesús Fidel, Melo-Aguilar, Camilo, Steinert, Norman Julius, García-Bustamante, Elena, de Vrese, Philip, Jungclaus, Johann, Lorenz, Stephan, Hagemann, Stefan, Cuesta-Valero, Francisco José, García-García, Almudena, and Beltrami, Hugo

Subjects
SURFACE temperature, GREENHOUSE effect, ATMOSPHERIC models, MODELS & modelmaking
Abstract

The anthropogenically-intensified greenhouse effect has caused a radiative imbalance at the top of the atmosphere during the industrial period. This, in turn, has led to an energy surplus in various components of the Earth system, with the ocean storing the largest part. The land contribution ranks second with the latest observational estimates based on borehole temperature profiles, which quantify the terrestrial energy surplus to be 6 % in the last five decades, whereas studies based on state-of-the-art climate models scale it down to 2 %. This underestimation stems from land surface models (LSMs) having a too shallow subsurface, which severely constrains the land heat uptake simulated by Earth System Models (ESMs). A forced simulation of the last 2000 years with the Max Planck Institute ESM (MPI-ESM) using a deep LSM captures 4 times more heat than the standard shallow MPI-ESM simulations in the historical period, well above the estimates provided by other ESMs. However, deepening the LSM does not remarkably affect the simulated surface temperature. It is shown that the heat stored during the historical period by an ESM using a deep LSM component can be accurately estimated by considering the surface temperatures simulated by the ESM using a shallow LSM and propagating them with a standalone forward model. This result is used to derive estimates of land heat uptake using all available observational datasets, reanalysis products, and state-of-the-art ESM experiments. This approach yields values of 10.5-16.0 ZJ for 1971-2018, slightly smaller than the latest borehole-based estimates (18.2 ZJ). [ABSTRACT FROM AUTHOR]

Published
2024
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25. No Consistent Simulated Trends in the Atlantic Meridional Overturning Circulation for the Past 6,000 Years

Author

Jiang, Zhiyi, primary, Brierley, Chris M., additional, Bader, Jürgen, additional, Braconnot, Pascale, additional, Erb, Michael, additional, Hopcroft, Peter O., additional, Jiang, Dabang, additional, Jungclaus, Johann, additional, Khon, Vyacheslav, additional, Lohmann, Gerrit, additional, Marti, Olivier, additional, Osman, Matthew B., additional, Otto‐Bliesner, Bette, additional, Schneider, Birgit, additional, Shi, Xiaoxu, additional, Thornalley, David J. R., additional, Tian, Zhiping, additional, and Zhang, Qiong, additional

Published
2023
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26. ICON-Sapphire: simulating the components of the Earth system and their interactions at kilometer and subkilometer scales

Author

Hohenegger, Cathy, Korn, Peter, Linardakis, Leonidas, Redler, René, Schnur, Reiner, Adamidis, Panagiotis, Bao, Jiawei, Bastin, Swantje, Behravesh, Milad, Bergemann, Martin, Biercamp, Joachim, Bockelmann, Hendryk, Brokopf, Renate, Brüggemann, Nils, Casaroli, Lucas, Chegini, Fatemeh, Datseris, George, Esch, Monika, Geet, George, Giorgetta, Marco, Gutjahr, Oliver, Haak, Helmuth, Hanke, Moritz, Ilyina, Tatiana, Jahns, Thomas, Jungclaus, Johann, Kern, Marcel, Klocke, Daniel, Kluft, Lukas, Kölling, Tobias, Kornblueh, Luis, Kosukhin, Sergey, Kroll, Clarissa, Lee, Junhong, Mauritsen, Thorsten, Mehlmann, Carolin, Mieslinger, Theresa, Naumann, Ann Kristin, Paccini, Laura, Peinado, Angel, Praturi, Divya Sri, Putrasahan, Dian, Rast, Sebastian, Riddick, Thomas, Roeber, Niklas, Schmidt, Hauke, Schulzweida, Uwe, Schütte, Florian, Segura, Hans, Shevchenko, Radomyra, Singh, Vikram, Specht, Mia, Stephan, Claudia Christine, von Storch, Jin-Song, Vogel, Raphaela, Wengel, Christian, Winkler, Marius, Ziemen, Florian, Marotzke, Jochem, and Stevens, Bjorn

Subjects
Ocean, Earth System Modeling, Tropics, General Medicine, Eddie Resolving, ICON-Saphire Model
Abstract

State-of-the-art Earth system models typically employ grid spacings of O(100 km), which is too coarse to explicitly resolve main drivers of the flow of energy and matter across the Earth system. In this paper, we present the new ICON-Sapphire model configuration, which targets a representation of the components of the Earth system and their interactions with a grid spacing of 10 km and finer. Through the use of selected simulation examples, we demonstrate that ICON-Sapphire can (i) be run coupled globally on seasonal timescales with a grid spacing of 5 km, on monthly timescales with a grid spacing of 2.5 km, and on daily timescales with a grid spacing of 1.25 km; (ii) resolve large eddies in the atmosphere using hectometer grid spacings on limited-area domains in atmosphere-only simulations; (iii) resolve submesoscale ocean eddies by using a global uniform grid of 1.25 km or a telescoping grid with the finest grid spacing at 530 m, the latter coupled to a uniform atmosphere; and (iv) simulate biogeochemistry in an ocean-only simulation integrated for 4 years at 10 km. Comparison of basic features of the climate system to observations reveals no obvious pitfalls, even though some observed aspects remain difficult to capture. The throughput of the coupled 5 km global simulation is 126 simulated days per day employing 21 % of the latest machine of the German Climate Computing Center. Extrapolating from these results, multi-decadal global simulations including interactive carbon are now possible, and short global simulations resolving large eddies in the atmosphere and submesoscale eddies in the ocean are within reach.

Published
2023

27. Skillful prediction of the 2015 summer 'cold blob' in the subpolar North Atlantic with the MPI-ESM1.2 'eddy-resolving' climate prediction system

Author

Lohmann, Katja, Gutjahr, Oliver, Jungclaus, Johann, and Matei, Daniela

Abstract

The subpolar North Atlantic is a hotspot with respect to predictability of sea surface temperature (SST) and upper-ocean heat content, as well as one of the regions worldwide, where initialisation with an observation-based state can further improve this predictability. In contrast to longer-term SST variability, high-frequency, impact-relevant extreme events are still challenging to predict by state-of-art decadal prediction systems.One such eventin the eastern subpolar North Atlantic is the record-cold anomaly in summer 2015, often referred to as "Cold Blob". We analyse ensemble prediction experiments with the MPI-ESM1.2 "eddy-resolving" climate prediction system initialized in November 2013 and 2014 to demonstrate that individual ensemble members can reforecast strength and extent of the 2015 summer record "Cold Blob". About half of the members initialized in November 2014 and one third of the members initialized in November 2013 reforecast cold SST conditions in the entire eastern subpolar North Atlantic, with maximum anomalies reaching a similar magnitude as in observations. With respect to upper-ocean heat content, we expect an even higher skill. As in the real world, strong surface heat loss in the (two) winter preceding winters plays a key role in maintainig and deepening the subpolar cold anomaly in most ensemble members reforecasting the "Cold Blob". In some ensemble members, oceanic drivers such as heat transport divergence seem to be important in shaping subpolar SST anomalies. Individual ensemble members reforecasting the "Cold Blob" also reforecast the associated European summer heat wave., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

40. Understanding AMOC stability: the North Atlantic Hosing Model Intercomparison Project

Author

Jackson, Laura Claire, primary, Alastrué de Asenjo, Eduardo, additional, Bellomo, Katinka, additional, Danabasoglu, Gokhan, additional, Haak, Helmuth, additional, Hu, Aixue, additional, Jungclaus, Johann, additional, Lee, Warren, additional, Meccia, Virna L., additional, Saenko, Oleg, additional, Shao, Andrew, additional, and Swingedouw, Didier, additional

Published
2022
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43. External forcing increases the occurrence of internally generated extreme events of North Atlantic Oscillation and East Atlantic pattern

Author

Liu, Quan, Jungclaus, Johann, Matei, Daniela, and Bader, Juergen

Abstract

External forcing is emerging as a factor influencing the internal variabilities of the climate system.However, the external forcing’s influence on the internal variabilities of the large-scale atmospheric circulation modes such as North Atlantic Oscillation (NAO) and East Atlantic (EA) pattern, has never been identified with a large ensemble model.The study analyzes the extreme events of NAO and EA using geopotential height data of the Max Planck Institute Grand Ensemble (MPI-GE)with 100 ensemble members. The internal variability is quantified as the deviation from the ensemble mean.The extreme NAO and EA are defined as those years where the indexes are above (positive extremes) or below (negative extremes) 2 standard deviations. The influence of global warming on the internal variability is checked with a 1pcCO2 experiment, where the CO2 concentration is increased by 1% every year.The results show increased occurrence of extreme events, especially negative extremes, for both NAO and EA during wintertime, in a warmer climate. While NAO extremes increase consistently across the whole troposphere, EA extremes increase more at higher altitudes (500hpa-200hpa) than at lower altitudes. The warming effect of positive extreme NAO over northern Eurasia gets weaker, while the cooling effect of negative extreme NAO over northern Eurasia gets stronger. The effects of both, positive and negative extremes of EA, extend eastward till Eastern Asia. This studyimplies that care should be taken when attributing the increased frequency of extreme weather events solely to global warming or internal variabilities of NAO and EA.&nbsp, The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

46. Greenhouse-gas forced changes in the Atlantic meridional overturning circulation and related worldwide sea-level change

Author

Couldrey, Matthew P., primary, Gregory, Jonathan M., additional, Dong, Xiao, additional, Garuba, Oluwayemi, additional, Haak, Helmuth, additional, Hu, Aixue, additional, Hurlin, William J., additional, Jin, Jiangbo, additional, Jungclaus, Johann, additional, Köhl, Armin, additional, Liu, Hailong, additional, Ojha, Sayantani, additional, Saenko, Oleg A., additional, Savita, Abhishek, additional, Suzuki, Tatsuo, additional, Yu, Zipeng, additional, and Zanna, Laure, additional

Published
2022
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48. ICON-Sapphire: simulating the components of the Earth System and their interactions at kilometer and subkilometer scales

Author

Hohenegger, Cathy, primary, Korn, Peter, additional, Linardakis, Leonidas, additional, Redler, René, additional, Schnur, Reiner, additional, Adamidis, Panagiotis, additional, Bao, Jiawei, additional, Bastin, Swantje, additional, Behravesh, Milad, additional, Bergemann, Martin, additional, Biercamp, Joachim, additional, Bockelmann, Hendryk, additional, Brokopf, Renate, additional, Brüggemann, Nils, additional, Casaroli, Lucas, additional, Chegini, Fatemeh, additional, Datseris, George, additional, Esch, Monika, additional, George, Geet, additional, Giorgetta, Marco, additional, Gutjahr, Oliver, additional, Haak, Helmuth, additional, Hanke, Moritz, additional, Ilyina, Tatiana, additional, Jahns, Thomas, additional, Jungclaus, Johann, additional, Kern, Marcel, additional, Klocke, Daniel, additional, Kluft, Lukas, additional, Kölling, Tobias, additional, Kornblueh, Luis, additional, Kosukhin, Sergey, additional, Kroll, Clarissa, additional, Lee, Junhong, additional, Mauritsen, Thorsten, additional, Mehlmann, Carolin, additional, Mieslinger, Theresa, additional, Naumann, Ann Kristin, additional, Paccini, Laura, additional, Peinado, Angel, additional, Praturi, Divya Sri, additional, Putrasahan, Dian, additional, Rast, Sebastian, additional, Riddick, Thomas, additional, Roeber, Niklas, additional, Schmidt, Hauke, additional, Schulzweida, Uwe, additional, Schütte, Florian, additional, Segura, Hans, additional, Shevchenko, Radomyra, additional, Singh, Vikram, additional, Specht, Mia, additional, Stephan, Claudia Christine, additional, von Storch, Jin-Song, additional, Vogel, Raphaela, additional, Wengel, Christian, additional, Winkler, Marius, additional, Ziemen, Florian, additional, Marotzke, Jochem, additional, and Stevens, Bjorn, additional

Published
2022
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