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1. Error Bounds for Compositions of Piecewise Affine Approximations

Author

Glunt, Jonah J., Siefert, Jacob A., Thompson, Andrew F., and Pangborn, Herschel C.

Subjects
Electrical Engineering and Systems Science - Systems and Control
Abstract

Nonlinear expressions are often approximated by piecewise affine (PWA) functions to simplify analysis or reduce computational costs. To reduce computational complexity, multivariate functions can be represented as compositions of functions with one or two inputs, which can be approximated individually. This paper provides efficient methods to generate PWA approximations of nonlinear functions via functional decomposition. The key contributions focus on intelligent placement of breakpoints for PWA approximations without requiring optimization, and on bounding the error of PWA compositions as a function of the error tolerance for each component of that composition. The proposed methods are used to systematically construct a PWA approximation for a complicated function, either to within a desired error tolerance or to a given level of complexity.

Published
2024

2. Ross Gyre variability modulates oceanic heat supply toward the West Antarctic continental shelf

Author

Prend, Channing J, MacGilchrist, Graeme A, Manucharyan, Georgy E, Pang, Rachel Q, Moorman, Ruth, Thompson, Andrew F, Griffies, Stephen M, Mazloff, Matthew R, Talley, Lynne D, and Gille, Sarah T

Subjects
Earth Sciences, Oceanography, Physical Geography and Environmental Geoscience, Geophysics, Climate Action, Earth sciences, Environmental sciences
Abstract

Abstract: West Antarctic Ice Sheet mass loss is a major source of uncertainty in sea level projections. The primary driver of this melting is oceanic heat from Circumpolar Deep Water originating offshore in the Antarctic Circumpolar Current. Yet, in assessing melt variability, open ocean processes have received considerably less attention than those governing cross-shelf exchange. Here, we use Lagrangian particle release experiments in an ocean model to investigate the pathways by which Circumpolar Deep Water moves toward the continental shelf across the Pacific sector of the Southern Ocean. We show that Ross Gyre expansion, linked to wind and sea ice variability, increases poleward heat transport along the gyre’s eastern limb and the relative fraction of transport toward the Amundsen Sea. Ross Gyre variability, therefore, influences oceanic heat supply toward the West Antarctic continental slope. Understanding remote controls on basal melt is necessary to predict the ice sheet response to anthropogenic forcing.

Published
2024

3. Set-valued State Estimation for Nonlinear Systems Using Hybrid Zonotopes

Author

Siefert, Jacob A., Thompson, Andrew F., Glunt, Jonah J., and Pangborn, Herschel C.

Subjects
Electrical Engineering and Systems Science - Systems and Control
Abstract

This paper proposes a method for set-valued state estimation of nonlinear, discrete-time systems. This is achieved by combining graphs of functions representing system dynamics and measurements with the hybrid zonotope set representation that can efficiently represent nonconvex and disjoint sets. Tight over-approximations of complex nonlinear functions are efficiently produced by leveraging special ordered sets and neural networks, which enable computation of set-valued state estimates that grow linearly in memory complexity with time. A numerical example demonstrates significant reduction of conservatism in the set-valued state estimates using the proposed method as compared to an idealized convex approach.

Published
2023

4. Reachability Analysis Using Hybrid Zonotopes and Functional Decomposition

Author

Siefert, Jacob A., Bird, Trevor J., Thompson, Andrew F., Glunt, Jonah J., Koeln, Justin P., Jain, Neera, and Pangborn, Herschel C.

Subjects
Electrical Engineering and Systems Science - Systems and Control
Abstract

This paper proposes methods for reachability analysis of nonlinear systems in both open loop and closed loop with advanced controllers. The methods combine hybrid zonotopes, a construct called a state-update set, functional decomposition, and special ordered set approximations to enable linear growth in reachable set memory complexity with time and linear scaling in computational complexity with the system dimension. Facilitating this combination are new identities for constructing nonconvex sets that contain nonlinear functions and for efficiently converting a collection of polytopes from vertex representation to hybrid zonotope representation. Benchmark numerical examples from the literature demonstrate the proposed methods and provide comparison to state-of-the-art techniques.

Published
2023

5. Antarctica and the Southern Ocean

Author

Clem, Kyle R, Adusumilli, Susheel, Baiman, Rebecca, Banwell, Alison F, Barreira, Sandra, Beadling, Rebecca L, Bozkurt, Deniz, Colwell, Steve, Coy, Lawrence, Datta, Rajashree T, De Laat, Jos, du Plessis, Marcel, Dunmire, Devon, Fogt, Ryan L, Freeman, Natalie M, Fricker, Helen A, Gardner, Alex S, Gille, Sarah T, Johnson, Bryan, Josey, Simon A, Keller, Linda M, Kramarova, Natalya A, Lazzara, Matthew A, Lieser, Jan L, MacFerrin, Michael, MacGilchrist, Graeme A, MacLennan, Michelle L, Massom, Robert A, Mazloff, Matthew R, Mikolajczyk, David E, Mote, Thomas L, Nash, Eric R, Newman, Paul A, Norton, Taylor, Ochwat, Naomi, Petropavlovskikh, Irina, Pezzi, Luciano P, Pitts, Michael, Raphael, Marilyn N, Reid, Phillip, Santee, Michelle L, Santini, Marcelo, Scambos, Theodore, Schultz, Cristina, Shi, Jia-Rui, Souza, Everaldo, Stammerjohn, Sharon, Strahan, Susan E, Thompson, Andrew F, Trusel, Luke D, Wille, Jonathan D, Yin, Ziqi, Allen, Jessicca, Camper, Amy V, Haley, Bridgette O, Hammer, Gregory, Love-Brotak, S Elizabeth, Ohlmann, Laura, Noguchi, Lukas, Riddle, Deborah B, and Veasey, Sara W

Subjects
Earth Sciences, Atmospheric Sciences, Climate Change Science, Astronomical and Space Sciences, Physical Geography and Environmental Geoscience, Meteorology & Atmospheric Sciences, Atmospheric sciences, Climate change science
Published
2023

6. A pole-to-equator ocean overturning circulation on Enceladus

Author

Lobo, Ana H., Thompson, Andrew F., Vance, Steven D., and Tharimena, Saikiran

Subjects
Astrophysics - Earth and Planetary Astrophysics, Physics - Fluid Dynamics
Abstract

Enceladus is believed to have a saltwater global ocean with a mean depth of at least 30~km, heated from below at the ocean-core interface and cooled at the top, where the ocean loses heat to the icy lithosphere above. This scenario suggests an important role for vertical convection to influence the interior properties and circulation of Enceladus' ocean. Additionally, the ice shell that encompasses the ocean has dramatic meridional thickness variations that, in steady state, must be sustained against processes acting to remove these ice thickness anomalies. One mechanism that would maintain variations in the ice shell thickness involves spatially-separated regions of freezing and melting at the ocean-ice interface. Here, we use an idealized, dynamical ocean model forced by an observationally-guided density forcing at the ocean-ice interface to argue that Enceladus' interior ocean should support a meridional overturning circulation. This circulation establishes an interior density structure that is more complex than in studies that have focused only on convection, including a shallow freshwater lens in the polar regions. Spatially-separated sites of ice formation and melt enable Enceladus to sustain a significant vertical and horizontal stratification, which impacts interior heat transport, and is critical for understanding the relationship between a global ocean and the planetary energy budget. The presence of low salinity layers near the polar ocean-ice interface also influences whether samples measured from the plumes are representative of the global ocean.

Published
2020
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7. Transient Overturning Compensation between Atlantic and Indo-Pacific Basins

Author

Sun, Shantong, Thompson, Andrew F, and Eisenman, Ian

Subjects
Climate Action, Oceanography, Maritime Engineering
Abstract

AbstractClimate models consistently project (i) a decline in the formation of North Atlantic Deep Water (NADW) and (ii) a strengthening of the Southern Hemisphere westerly winds in response to anthropogenic greenhouse gas forcing. These two processes suggest potentially conflicting tendencies of the Atlantic meridional overturning circulation (AMOC): a weakening AMOC due to changes in the North Atlantic but a strengthening AMOC due to changes in the Southern Ocean. Here we focus on the transient evolution of the global ocean overturning circulation in response to a perturbation to the NADW formation rate. We propose that the adjustment of the Indo-Pacific overturning circulation is a critical component in mediating AMOC changes. Using a hierarchy of ocean and climate models, we show that the Indo-Pacific overturning circulation provides the first response to AMOC changes through wave processes, whereas the Southern Ocean overturning circulation responds on longer (centennial to millennial) time scales that are determined by eddy diffusion processes. Changes in the Indo-Pacific overturning circulation compensate AMOC changes, which allows the Southern Ocean overturning circulation to evolve independently of the AMOC, at least over time scales up to many decades. In a warming climate, the Indo-Pacific develops an overturning circulation anomaly associated with the weakening AMOC that is characterized by a northward transport close to the surface and a southward transport in the deep ocean, which could effectively redistribute heat between the basins. Our results highlight the importance of interbasin exchange in the response of the global ocean overturning circulation to a changing climate.

Published
2020

9. Constraining Southern Ocean Air-Sea-Ice Fluxes Through Enhanced Observations

Author

Swart, Sebastiaan, Gille, Sarah T, Delille, Bruno, Josey, Simon, Mazloff, Matthew, Newman, Louise, Thompson, Andrew F, Thomson, Jim, Ward, Brian, du Plessis, Marcel D, Kent, Elizabeth C, Girton, James, Gregor, Luke, Heil, Petra, Hyder, Patrick, Pezzi, Luciano Ponzi, de Souza, Ronald Buss, Tamsitt, Veronica, Weller, Robert A, and Zappa, Christopher J

Subjects
air-sea/air-sea-ice fluxes, Southern Ocean, ocean-atmosphere interaction, climate, ocean-ice interaction, Oceanography, Ecology
Published
2019

11. Sources of low-frequency variability in observed Antarctic sea ice.

Author

Bonan, David B., Dörr, Jakob, Wills, Robert C. J., Thompson, Andrew F., and Årthun, Marius

Subjects
ANTARCTIC ice, ANTARCTIC oscillation, SEA ice, WESTERLIES, EL Nino, OCEAN temperature
Abstract

Antarctic sea ice has exhibited significant variability over the satellite record, including a period of prolonged and gradual expansion, as well as a period of sudden decline. A number of mechanisms have been proposed to explain this variability, but how each mechanism manifests spatially and temporally remains poorly understood. Here, we use a statistical method called low-frequency component analysis to analyze the spatiotemporal structure of observed Antarctic sea ice concentration variability. The identified patterns reveal distinct modes of low-frequency sea ice variability. The leading mode, which accounts for the large-scale, gradual expansion of sea ice, is associated with the Interdecadal Pacific Oscillation and resembles the observed sea surface temperature trend pattern that climate models have trouble reproducing. The second mode is associated with the central Pacific El Niño–Southern Oscillation (ENSO) and the Southern Annular Mode and accounts for most of the sea ice variability in the Ross Sea. The third mode is associated with the eastern Pacific ENSO and Amundsen Sea Low and accounts for most of the pan-Antarctic sea ice variability and almost all of the sea ice variability in the Weddell Sea. The third mode is also related to periods of abrupt Antarctic sea ice decline that are associated with a weakening of the circumpolar westerlies, which favors surface warming through a shoaling of the ocean mixed layer and decreased northward Ekman heat transport. Broadly, these results suggest that climate model biases in long-term Antarctic sea ice and large-scale sea surface temperature trends are related to each other and that eastern Pacific ENSO variability is a key ingredient for abrupt Antarctic sea ice changes. [ABSTRACT FROM AUTHOR]

Published
2024
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12. Ocean Convective Available Potential Energy. Part II: Energetics of Thermobaric Convection and Thermobaric Cabbeling

Author

Su, Zhan, Ingersoll, Andrew P, Stewart, Andrew L, and Thompson, Andrew F

Subjects
Conditional instability, Diapycnal mixing, Deep convection, Energy transport, Circulation/ Dynamics, Instability, Convection, Oceanography, Maritime Engineering
Abstract

The energetics of thermobaricity- and cabbeling-powered deep convection occurring in oceans with cold freshwater overlying warm salty water are investigated here. These quasi-two-layer profiles are widely observed in wintertime polar oceans. The key diagnostic is the ocean convective available potential energy (OCAPE), a concept introduced in a companion piece to this paper (Part I). For an isolated ocean column, OCAPE arises from thermobaricity and is the maximum potential energy (PE) that can be converted into kinetic energy (KE) under adiabatic vertical parcel rearrangements. This study explores the KE budget of convection using two-dimensional numerical simulations and analytical estimates. The authors find that OCAPE is a principal source for KE. However, the complete conversion of OCAPE to KE is inhibited by diabatic processes. Further, this study finds that diabatic processes produce three other distinct contributions to the KE budget: (i) a sink of KE due to the reduction of stratification by vertical mixing, which raises water column's center of mass and thus acts to convert KE to PE; (ii) a source of KE due to cabbeling-induced shrinking of the water column's volume when water masses with different temperatures are mixed, which lowers the water column's center of mass and thus acts to convert PE into KE; and (iii) a reduced production of KE due to diabatic energy conversion of the KE convertible part of the PE to the KE inconvertible part of the PE. Under some simplifying assumptions, the authors also propose a theory to estimate the maximum depth of convection from an energetic perspective. This study provides a potential basis for improving the convection parameterization in ocean models.

Published
2016

13. Ocean Convective Available Potential Energy. Part I: Concept and Calculation

Author

Su, Zhan, Ingersoll, Andrew P, Stewart, Andrew L, and Thompson, Andrew F

Subjects
Life Below Water, Fluxes, Deep convection, Convection, Conditional instability, Diapycnal mixing, Energy transport, Circulation/ Dynamics, Oceanography, Maritime Engineering
Abstract

Thermobaric convection (type II convection) and thermobaric cabbeling (type III convection) might substantially contribute to vertical mixing, vertical heat transport, and deep-water formation in the World Ocean. However, the extent of this contribution remains poorly constrained. The concept of ocean convective available potential energy (OCAPE), the thermobaric energy source for type II and type III convection, is introduced to improve the diagnosis and prediction of these convection events. OCAPE is analogous to atmospheric CAPE, which is a key energy source for atmospheric moist convection and has long been used to forecast moist convection. OCAPE is the potential energy (PE) stored in an ocean column arising from thermobaricity, defined as the difference between the PE of the ocean column and its minimum possible PE under adiabatic vertical parcel rearrangements. An ocean column may be stably stratified and still have nonzero OCAPE. The authors present an efficient strategy for computing OCAPE accurately for any given column of seawater. They further derive analytical expressions for OCAPE for approximately two-layer ocean columns that are widely observed in polar oceans. This elucidates the dependence of OCAPE on key physical parameters. Hydrographic profiles from the winter Weddell Sea are shown to contain OCAPE (0.001-0.01 J kg-1), and scaling analysis suggests that OCAPE may be substantially enhanced by wintertime surface buoyancy loss. The release of this OCAPE may substantially contribute to the kinetic energy of deep convection in polar oceans.

Published
2016

18. Marine ice-sheet profiles and stability under Coulomb basal conditions

Author

Tsai, Victor C, Stewart, Andrew L, and Thompson, Andrew F

Subjects
Climate Action, Antarctic glaciology, glacial rheology, glacier mechanics, glacier modelling, ice-sheet modelling, Physical Geography and Environmental Geoscience, Meteorology & Atmospheric Sciences
Abstract

The behavior of marine-terminating ice sheets, such as the West Antarctic ice sheet, is of interest due to the possibility of rapid grounding-line retreat and consequent catastrophic loss of ice. Critical to modeling this behavior is a choice of basal rheology, where the most popular approach is to relate the ice-sheet velocity to a power-law function of basal stress. Recent experiments, however, suggest that near-grounding line tills exhibit Coulomb friction behavior. Here we address how Coulomb conditions modify ice-sheet profiles and stability criteria. The basal rheology necessarily transitions to Coulomb friction near the grounding line, due to low effective stresses, leading to changes in ice-sheet properties within a narrow boundary layer. Ice-sheet profiles 'taper off' towards a flatter upper surface, compared with the power-law case, and basal stresses vanish at the grounding line, consistent with observations. In the Coulomb case, the grounding-line ice flux also depends more strongly on flotation ice thickness, which implies that ice sheets are more sensitive to climate perturbations. Furthermore, with Coulomb friction, the ice sheet grounds stably in shallower water than with a power-law rheology. This implies that smaller perturbations are required to push the grounding line into regions of negative bed slope, where it would become unstable. These results have important implications for ice-sheet stability in a warming climate.

Published
2015

19. Eddy‐Induced Dispersion of Sea Ice Floes at the Marginal Ice Zone.

Author

Gupta, Mukund, Gürcan, Emma, and Thompson, Andrew F.

Subjects
ICE floes, SEA ice, ICE prevention & control, OCEAN currents, SEAWATER, MECHANICAL energy
Abstract

Ocean heat exchanges at the marginal ice zone (MIZ) play an important role in melting sea ice. Mixed‐layer eddies transport heat and ice floes across the MIZ, facilitating the pack's access to warm waters. This study explores these frontal dynamics using disk‐shaped floes coupled to an upper‐ocean model simulating the sea ice edge. Numerical experiments reveal that small floes respond more strongly to fine‐scale ocean currents, which favors higher dispersion rates and weakens sea ice drag onto the underlying ocean. Floes with radii smaller than resolved turbulent filaments (∼2–4 km) result in a wider and more energetic MIZ, by a factor of 70% each, compared to larger floes. We hypothesize that this floe size dependency may affect sea ice break‐up by controlling oceanic energy propagation into the MIZ and modulate the sea ice pack's melt rate by regulating lateral heat transport toward the sea ice cover. Plain Language Summary: Sea ice forms as a thin layer of frozen ocean waters, which breaks into individual floes due to the action of waves, ocean currents, and atmospheric winds. At the edge of the pack, these floes are vulnerable to warm waters in the open ocean, which can favor the melt of sea ice. The transport of heat from the open ocean into ice‐covered regions is not well represented in existing climate models, notably due to their poor spatial resolution and their inability to represent the dynamics of individual floes. In this study, we use a regional numerical model to investigate how fine‐scale ocean currents (2–30 km) can help transport heat toward a sea ice pack composed of broken‐up floes. We find that this heat transport is most efficient when floes are small, because they cannot efficiently damp the mechanical energy from the surface currents and they are easily transported into the open ocean by these currents. These two processes combined may lead to sea ice melt feedbacks that are currently not captured by coarser climate models. Key Points: The sensitivity of sea ice dispersion and upper‐ocean energetics to floe size is considered at a mesoscale frontFloes smaller than turbulent filaments disperse more strongly and lead to a wider marginal ice zoneThese small floes allow for stronger eddy kinetic energy propagation and heat transport into the pack [ABSTRACT FROM AUTHOR]

Published
2024
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21. Introduction

Author

Boyer, Tim, primary, Bartow-Gillies, Ellen, additional, Abida, A., additional, Ades, Melanie, additional, Adler, Robert, additional, Adusumilli, Susheel, additional, Agyakwah, W., additional, Ahmasuk, Brandon, additional, Aldeco, Laura S., additional, Alexe, Mihai, additional, Alfaro, Eric J., additional, Allan, Richard P., additional, Allgood, Adam, additional, Alves, Lincoln. M., additional, Amador, Jorge A., additional, Anderson, John, additional, Andrade, B., additional, Anneville, Orlane, additional, Aono, Yasuyuki, additional, Arguez, Anthony, additional, Arosio, Carlo, additional, Atkinson, C., additional, Augustine, John A., additional, Avalos, Grinia, additional, Azorin-Molina, Cesar, additional, Backensto, Stacia A., additional, Bader, Stephan, additional, Baez, Julian, additional, Baiman, Rebecca, additional, Ballinger, Thomas J., additional, Banwell, Alison F., additional, Bardin, M. Yu, additional, Barichivich, Jonathan, additional, Barnes, John E., additional, Barreira, Sandra, additional, Beadling, Rebecca L., additional, Beck, Hylke E., additional, Becker, Emily J., additional, Bekele, E., additional, Bellido, Guillem Martín, additional, Bellouin, Nicolas, additional, Benedetti, Angela, additional, Benestad, Rasmus, additional, Berne, Christine, additional, Berner, Logan. T., additional, Bernhard, Germar H., additional, Bhatt, Uma S., additional, Bhuiyan, A. E., additional, Bigalke, Siiri, additional, Biló, Tiago, additional, Bissolli, Peter, additional, Bjerke Jarle, W., additional, Blagrave, Kevin, additional, Blake, Eric S., additional, Blenkinsop, Stephen, additional, Blunden, Jessica, additional, Bochníček, Oliver, additional, Bock, Olivier, additional, Bodenstein, Barbara, additional, Bodin, Xavier, additional, Bosilovich, Michael, additional, Boucher, Olivier, additional, Bozkurt, Deniz, additional, Brettschneider, Brian, additional, Bringas, Francis G., additional, Bringas, Francis, additional, Buechler, Dennis, additional, Buehler, Stefan A., additional, Bukunt, Brandon, additional, Calderón, Blanca, additional, Camargo, Suzana J., additional, Campbell, Jayaka, additional, Campos, Diego, additional, Carrea, Laura, additional, Carter, Brendan R., additional, Cetinić, Ivona, additional, Chambers, Don P., additional, Chan, Duo, additional, Chandler, Elise, additional, Chang, Kai-Lan, additional, Chen, Hua, additional, Chen, Lin, additional, Cheng, Lijing, additional, Cheng, Vincent Y. S., additional, Chomiak, Leah, additional, Christiansen, Hanne H., additional, Christy, John R., additional, Chung, Eui-Seok, additional, Ciasto, Laura M., additional, Clarke, Leonardo, additional, Clem, Kyle R., additional, Clingan, Scott, additional, Coelho, Caio A.S., additional, Cohen, Judah L., additional, Coldewey-Egbers, Melanie, additional, Colwell, Steve, additional, Cooper, Owen R., additional, Cornes, Richard C., additional, Correa, Kris, additional, Costa, Felipe, additional, Covey, Curt, additional, Coy, Lawrence, additional, Créatux, Jean-François, additional, Crhova, Lenka, additional, Crimmins, Theresa, additional, Cronin, Meghan F., additional, Cropper, Thomas, additional, Crotwell, Molly, additional, Culpepper, Joshua, additional, Cunha, Ana P., additional, Cusicanqui, Diego, additional, Datta, Rajashree T., additional, Davis, Sean M., additional, De Bock, Veerle, additional, de Jeu, Richard A. M., additional, De Laat, Jos, additional, Decharme, Bertrand, additional, Degenstein, Doug, additional, Delaloye, Reynald, additional, Demircan, Mesut, additional, Derksen, Chris, additional, Deus, Ricardo, additional, Dhurmea, K. R., additional, Diamond, Howard J., additional, Dirkse, S., additional, Divine, Dmitry, additional, Dokulil, Martin T., additional, Donat, Markus G., additional, Dong, Shenfu, additional, Dorigo, Wouter A., additional, Drost Jensen, Caroline, additional, Druckenmiller, Matthew L., additional, Drumond, Paula, additional, du Plessis, Marcel, additional, Dugan, Hilary A., additional, Dulamsuren, Dashkhuu, additional, Dunmire, Devon, additional, Dunn, Robert J. H., additional, Durre, Imke, additional, Dusek, Robert, additional, Dutton, Geoff, additional, Duveiller, Gregory, additional, Ekici, Mithat, additional, Elias Chereque, Alesksandra, additional, ElKharrim, M., additional, Epstein, Howard E., additional, Espinoza, Jhan-Carlo, additional, Estilow, Thomas W., additional, Estrella, Nicole, additional, Fauchereau, Nicolas, additional, Fausto, Robert S., additional, Feely, Richard A., additional, Fenimore, Chris, additional, Fereday, David, additional, Fettweis, Xavier, additional, Fioletov, vitali E., additional, Flemming, Johannes, additional, Fogarty, Chris, additional, Fogt, Ryan L., additional, Forbes, Bruce C., additional, Foster, Michael J., additional, Franz, Bryan A., additional, Freeman, Natalie M., additional, Fricker, Helen A., additional, Frith, Stacey M., additional, Froidevaux, Lucien, additional, Frost, Gerald V. (JJ), additional, Fuhrman, Steven, additional, Füllekrug, Martin, additional, Ganter, Catherine, additional, Gao, Meng, additional, Gardner, Alex S., additional, Garforth, Judith, additional, Garg, Jay, additional, Gerland, Sebastian, additional, Gibbes, Badin, additional, Gille, Sarah T., additional, Gilson, John, additional, Gleason, Karin, additional, Gobron, Nadine, additional, Goetz, Scott J., additional, Goldenberg, Stanley B., additional, Goni, Gustavo, additional, Goodman, Steven, additional, Goto, Atsushi, additional, Grooß, Jens-Uwe, additional, Gruber, Alexander, additional, Gu, Guojun, additional, Guard, Charles “Chip” P., additional, Hagos, S., additional, Hahn, Sebastian, additional, Haimberger, Leopold, additional, Hall, Bradley D., additional, Hamlington, Benjamin D., additional, Hanna, Edward, additional, Hanssen-Bauer, Inger, additional, Harnos, Daniel S., additional, Harris, Ian, additional, He, Qiong, additional, Heim, Richard R., additional, Hellström, Sverker, additional, Hemming, Deborah L., additional, Hendricks, Stefan, additional, Hicks, J., additional, Hidalgo, Hugo G., additional, Hirschi, Martin, additional, Ho, Shu-peng (Ben), additional, Hobbs, W., additional, Holmes, Robert M., additional, Holzworth, Robert, additional, Hrbáček, Filip, additional, Hu, Guojie, additional, Hu, Zeng-Zhen, additional, Huang, Boyin, additional, Huang, Hongjie, additional, Hurst, Dale F., additional, Ialongo, Iolanda, additional, Inness, Antje, additional, Isaksen, Ketil, additional, Ishii, Masayoshi, additional, Jadra, Gerardo, additional, Jevrejeva, Svetlana, additional, John, Viju O., additional, Johns, W., additional, Johnsen, Bjørn, additional, Johnson, Bryan, additional, Johnson, Gregory C., additional, Jones, Philip D., additional, Jones, Timothy, additional, Josey, Simon A., additional, Jumaux, G., additional, Junod, Robert, additional, Kääb, Andreas, additional, Kabidi, K., additional, Kaiser, Johannes W., additional, Kaler, Robb S.A., additional, Kaleschke, Lars, additional, Kaufmann, Viktor, additional, Kazemi, Amin Fazl, additional, Keller, Linda M., additional, Kellerer-Pirklbauer, Andreas, additional, Kendon, Mike, additional, Kennedy, John, additional, Kent, Elizabeth C., additional, Kerr, Kenneth, additional, Khan, Valentina, additional, Khiem, Mai Van, additional, Kidd, Richard, additional, Kim, Mi Ju, additional, Kim, Seong-Joong, additional, Kipling, Zak, additional, Klotzbach, Philip J., additional, Knaff, John A., additional, Koppa, Akash, additional, Korshunova, Natalia N., additional, Kraemer, Benjamin M., additional, Kramarova, Natalya A., additional, Kruger, A. C., additional, Kruger, Andries, additional, Kumar, Arun, additional, L’Heureux, Michelle, additional, La Fuente, Sofia, additional, Laas, Alo, additional, Labe, Zachary M., additional, Lader, Rick, additional, Lakatos, Mónika, additional, Lakkala, Kaisa, additional, Lam, Hoang Phuc, additional, Lan, Xin, additional, Landschützer, Peter, additional, Landsea, Chris W., additional, Lang, Timothy, additional, Lankhorst, Matthias, additional, Lantz, Kathleen O., additional, Lara, Mark J., additional, Lavado-Casimiro, Waldo, additional, Lavers, David A., additional, Lazzara, Matthew A., additional, Leblanc, Thierry, additional, Lee, Tsz-Cheung, additional, Leibensperger, Eric M., additional, Lennard, Chris, additional, Leuliette, Eric, additional, Leung, Kinson H. Y., additional, Lieser, Jan L., additional, Likso, Tanja, additional, Lin, I-I., additional, Lindsey, Jackie, additional, Liu, Yakun, additional, Locarnini, Ricardo, additional, Loeb, Norman G., additional, Loomis, Bryant D., additional, Lorrey, Andrew M., additional, Loyola, Diego, additional, Lu, Rui, additional, Lumpkin, Rick, additional, Luo, Jing-Jia, additional, Luojus, Kari, additional, Lyman, John M., additional, Maberly, Stephen C., additional, Macander, Matthew J., additional, MacFerrin, Michael, additional, MacGilchrist, Graeme A., additional, MacLennan, Michelle L., additional, Madelon, Remi, additional, Magee, Andrew D., additional, Magnin, Florence, additional, Mamen, Jostein, additional, Mankoff, Ken D., additional, Manney, Gloria L., additional, Marcinonienė, Izolda, additional, Marengo, Jose A., additional, Marjan, Mohammadi, additional, Martínez, Ana E., additional, Massom, Robert A., additional, Matsuzaki, Shin-Ichiro, additional, May, Linda, additional, Mayer, Michael, additional, Mazloff, Matthew R., additional, McAfee, Stephanie A., additional, McBride, C., additional, McCabe, Matthew F., additional, McClelland, James W., additional, McPhaden, Michael J., additional, Mcvicar, Tim R., additional, Mears, Carl A., additional, Meier, Walter N., additional, Mekonnen, A., additional, Menzel, Annette, additional, Merchant, Christopher J., additional, Merrifield, Mark A., additional, Meyer, Michael F., additional, Meyers, Tristan, additional, Mikolajczyk, David E., additional, Miller, John B., additional, Miralles, Diego G., additional, Misevicius, Noelia, additional, Mishonov, Alexey, additional, Mitchum, Gary T., additional, Moat, Ben I., additional, Moesinger, Leander, additional, Moise, Aurel, additional, Molina-Carpio, Jorge, additional, Monet, Ghislaine, additional, Montzka, Stephan A., additional, Moon, Twila A., additional, Moore, G. W. K., additional, Mora, Natali, additional, Morán, Johnny, additional, Morehen, Claire, additional, Morice, Colin, additional, Mostafa, A. E., additional, Mote, Thomas L., additional, Mrekaj, Ivan, additional, Mudryk, Lawrence, additional, Mühle, Jens, additional, Müller, Rolf, additional, Nance, David, additional, Nash, Eric R., additional, Nerem, R. Steven, additional, Newman, Paul A., additional, Nicolas, Julien P., additional, Nieto, Juan J., additional, Noetzli, Jeannette, additional, Noll, Ben, additional, Norton, Taylor, additional, Nyland, Kelsey E., additional, O’Keefe, John, additional, Ochwat, Naomi, additional, Oikawa, Yoshinori, additional, Okunaka, Yuka, additional, Osborn, Timothy J., additional, Overland, James E., additional, Park, Taejin, additional, Parrington, Mark, additional, Parrish, Julia K., additional, Pasch, Richard J., additional, Pascual Ramírez, Reynaldo, additional, Pellet, Cécile, additional, Pelto, Mauri S., additional, Perčec Tadić, Melita, additional, Perovich, Donald K., additional, Petersen, Guðrún Nína, additional, Petersen, Kyle, additional, Petropavlovskikh, Irina, additional, Petty, Alek, additional, Pezza, Alexandre B., additional, Pezzi, Luciano P., additional, Phillips, Coda, additional, Phoenix, Gareth K., additional, Pierson, Don, additional, Pinto, Izidine, additional, Pires, Vanda, additional, Pitts, Michael, additional, Po-Chedley, Stephen, additional, Pogliotti, Paolo, additional, Poinar, Kristin, additional, Polvani, Lorenzo, additional, Preimesberger, Wolfgang, additional, Price, Colin, additional, Pulkkanen, Merja, additional, Purkey, Sarah G., additional, Qiu, Bo, additional, Quisbert, Kenny, additional, Quispe, Willy R., additional, Rajeevan, M., additional, Ramos, Andrea M., additional, Randel, William J., additional, Rantanen, Mika, additional, Raphael, Marilyn N., additional, Reagan, James, additional, Recalde, Cristina, additional, Reid, Phillip, additional, Rémy, Samuel, additional, Reyes Kohler, Alejandra J., additional, Ricciardulli, Lucrezia, additional, Richardson, Andrew D., additional, Ricker, Robert, additional, Robinson, David A., additional, Robjhon, M., additional, Rocha, Willy, additional, Rodell, Matthew, additional, Rodriguez Guisado, Esteban, additional, Rodriguez-Fernandez, Nemesio, additional, Romanovsky, Vladimir E., additional, Ronchail, Josyane, additional, Rosencrans, Matthew, additional, Rosenlof, Karen H., additional, Rösner, Benjamin, additional, Rösner, Henrieke, additional, Rozanov, Alexei, additional, Rozkošný, Jozef, additional, Rubek, Frans, additional, Rusanovskaya, Olga O., additional, Rutishauser, This, additional, Sabeerali, C. T., additional, Salinas, Roberto, additional, Sánchez-Lugo, Ahira, additional, Santee, Michelle L., additional, Santini, Marcelo, additional, Sato, Katsunari, additional, Sawaengphokhai, Parnchai, additional, Sayouri, A., additional, Scambos, Theodore, additional, Schenzinger, Verena, additional, Schimanke, Semjon, additional, Schlegel, Robert W., additional, Schmid, Claudia, additional, Schmid, Martin, additional, Schneider, Udo, additional, Schreck, Carl J., additional, Schultz, Cristina, additional, _, _, additional, Segele, Z. T., additional, Sensoy, Serhat, additional, Serbin, Shawn P., additional, Serreze, Mark C., additional, Setiawan, Amsari Mudzakir, additional, Sezaki, Fumi, additional, Sharma, Sapna, additional, Sharp, Jonathan D., additional, Sheffield, Gay, additional, Shi, Jia-Rui, additional, Shi, Lei, additional, Shiklomanov, Alexander I., additional, Shiklomanov, Nikolay I., additional, Shimaraeva, Svetlana V., additional, Shukla, R., additional, Siegel, David A., additional, Silow, Eugene A., additional, Sima, F., additional, Simmons, Adrian J., additional, Smeed, David A., additional, Smith, Adam, additional, Smith, Matthew M., additional, Smith, Sharon L., additional, Soden, Brian J., additional, Sofieva, Viktoria, additional, Souza, Everaldo, additional, Sparks, Tim H., additional, Spence-Hemmings, Jacqueline, additional, Spencer, Robert G. M., additional, Spillane, Sandra, additional, Sreejith, O. P., additional, Srivastava, A. K., additional, Stackhouse, Paul W., additional, Stammerjohn, Sharon, additional, Stauffer, Ryan, additional, Steinbrecht, Wolfgang, additional, Steiner, Andrea K., additional, Stella, Jose L., additional, Stephenson, Tannecia S., additional, Stradiotti, Pietro, additional, Strahan, Susan E., additional, Streletskiy, Dmitry A., additional, Surendran, Divya E., additional, Suslova, Anya, additional, Svendby, Tove, additional, Sweet, William, additional, Takahashi, Kiyotoshi, additional, Takemura, Kazuto, additional, Tank, Suzanne E., additional, Taylor, Michael A., additional, Tedesco, Marco, additional, Thackeray, Stephen J., additional, Thiaw, W. M., additional, Thibert, Emmanuel, additional, Thoman, Richard L., additional, Thompson, Andrew F., additional, Thompson, Philip R., additional, Tian-Kunze, Xiangshan, additional, Timmermans, Mary-Louise, additional, Timofeyev, Maxim A., additional, Tobin, Skie, additional, Tømmervik, Hans, additional, Tourpali, Kleareti, additional, Trescilo, Lidia, additional, Tretiakov, Mikhail, additional, Trewin, Blair C., additional, Triñanes, Joaquin A., additional, Trotman, Adrian, additional, Truchelut, Ryan E., additional, Trusel, Luke D., additional, Tye, Mari R., additional, van der A, Ronald, additional, van der Schalie, Robin, additional, van der Schrier, Gerard, additional, Van Hemert, Caroline, additional, Van Meerbeeck, Cedric J., additional, van vliet, Arnold J.H., additional, Vazife, Ahad, additional, Verburg, Piet, additional, Vernier, Jean-Paul, additional, Vimont, Isaac J., additional, Virts, Katrina, additional, Vivero, Sebastián, additional, Volkov, Denis L., additional, Vömel, Holger, additional, Vose, Russell S., additional, Walker, Donald (Skip) A., additional, Walsh, John E., additional, Wang, Bin, additional, Wang, Hui, additional, Wang, Muyin, additional, Wang, Ray H. J., additional, Wang, Xinyue, additional, Wanninkhof, Rik, additional, Warnock, Taran, additional, Weber, Mark, additional, Webster, Melinda, additional, Wehrlé, Adrian, additional, Wen, Caihong, additional, Westberry, Toby K., additional, Widlansky, Matthew J., additional, Wiese, David N., additional, Wild, Jeannette D., additional, Wille, Jonathan D., additional, Willems, An, additional, Willett, Kate M., additional, Williams, Earle, additional, Willis, J., additional, Wong, Takmeng, additional, Wood, Kimberly M., additional, Woolway, Richard Iestyn, additional, Xie, Ping-Ping, additional, Yang, Daqing, additional, Yin, Xungang, additional, Yin, Ziqi, additional, Zeng, Zhenzhong, additional, Zhang, Huai-min, additional, Zhang, Li, additional, Zhang, Peiqun, additional, Zhao, Lin, additional, Zhou, Xinjia, additional, Zhu, Zhiwei, additional, Ziemke, Jerry R., additional, Ziese, Markus, additional, Zolkos, Scott, additional, Zotta, Ruxandra M., additional, Zou, Cheng-Zhi, additional, Allen, Jessicca, additional, Camper, Amy V., additional, Haley, Bridgette O., additional, Hammer, Gregory, additional, Love-Brotak, S. Elizabeth, additional, Ohlmann, Laura, additional, Noguchi, Lukas, additional, Riddle, Deborah B., additional, and Veasey, Sara W., additional

Published
2023
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24. Submesoscale Dynamics in the Upper Ocean

Author

Taylor, John R. and Thompson, Andrew F.

Subjects
Condensed Matter Physics
Abstract

Oceanic motions with spatial scales of 200 m–20 km, called submesoscales, are ubiquitous in the upper ocean and serve as a key intermediary between larger-scale balanced dynamics and unbalanced turbulence. Here, we introduce the fluid dynamics of submesoscales and contrast them with motions at larger and smaller scales. We summarize the various ways in which submesoscales develop due to instabilities that extract potential or kinetic energy from larger-scale balanced currents; some instabilities have counterparts at larger scales, while others are distinct to the submesoscale regime. Submesoscales modify the density stratification in the upper ocean and redistribute energy between scales. These energy transfers are complex, having both up-scale and down-scale components. Submesoscale eddies and fronts also contribute to a spatially heterogeneous distribution of shear and restratification that leave an imprint on upper ocean turbulence. The impact of submesoscales on the Earth's climate remains an exciting research frontier.

Published
2023

25. Sources and pathways of glacial meltwater in the Bellingshausen Sea, Antarctica

Author

Sheehan, Peter M. F., Heywood, Karen J., Thompson, Andrew F., Flexas, M. Mar, and Shodlok, Michael P.

Abstract

Meltwater content and pathways determine the impact of Antarctica's melting ice shelves on ocean circulation and climate. Using ocean glider observations, we quantify meltwater distribution and transport within the Bellingshausen Sea's Belgica Trough. Meltwater is present at different densities and with different turbidities: both are indicative of a layer's ice shelf of origin. To investigate how ice-shelf origin separates meltwater into different export pathways, we compare these observations with high-resolution tracer-release model simulations. Meltwater filaments branch off the Antarctic Coastal Current into the southwestern trough. Meltwater also enters the Belgica Trough in the northwest via an extended western pathway, hence the greater observed southward (0.50 mSv) than northward (0.17 mSv) meltwater transport. Together, the observations and simulations reveal meltwater retention within a cyclonic in-trough gyre, which has the potential to promote climactically important feedbacks on circulation and future melting.

Published
2023

26. Coastal buoyancy controls on multiple melt regimes of warm West Antarctic ice shelves

Author

Moorman, Ruth, Thompson, Andrew F, and Wilson, Earle A

Abstract

Mass loss from the West Antarctic Ice Sheet is currently dominated by discharge through ice shelves exposed to warm modified Circumpolar Deep Waters (mCDW). Basal melt rates in these regions track decadal scale oscillations in the depth of the thermocline separating mCDW from cooler near-surface waters. Prior work has attributed the observed thermocline depth variability to wind-driven variations in shoreward mCDW transport. Here, we show that transformation of mCDW in coastal polynyas also impacts mCDW thickness variability, and we compare the importance of this mechanism to shelf break wind forcing.We introduce a simple overturning circulation model for the continental shelf that distinguishes between thermocline depth variability associated with mCDW supply and mCDW transformation. This model indicates that surface buoyancy fluxes within coastal polynyas can generate large decadal variations in thermocline depth in the absence of variable mCDW inflow, posing an alternative mechanism for observed mCDW thickness variability. The modeled variability takes the form of transitions between bistable high and low melt regimes, made possible by feedbacks between basal ice melt and stratification at the ice front. Our simple model can explain both the magnitude of observed thermocline depth variations and their lagged correlation with stratification strength, which are not fully accounted for in work focussed on wind forcing. The work suggests a previously underestimated role for coastal polynya dynamics in setting the melt rates of West Antarctic ice shelves and demonstrates the utility of framing the transport of ocean heat towards ice shelves in terms of an overturning circulation., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

27. Heat transport towards sea ice by mesoscale eddies in an idealized Southern Ocean

Author

Rieck, Jan, Dufour, Carolina O., Nadeau, Louis-Philippe, and Thompson, Andrew F.

Abstract

The contribution of mesoscale eddies to heat transport can be important in regions with high eddy kinetic energy such as the Southern Ocean. However, there are large gaps in our understanding of this contribution towards seasonally sea ice-covered regions due to the lack of observations and resolution in ocean and climate models. Using an idealized configuration of the Southern Ocean at 10 km horizontal resolution, we investigate the contribution of the resolved mesoscale, that is all transient processes, to the total heat transport towards and under the sea ice in the Southern Ocean. We find that the southward total heat transport is mainly driven by the transient heat transport. We then extract the heat transport by coherent mesoscale eddies from that of all transient processes using an eddy detection and tracking algorithm. Coherent eddies contribute 40-50% to the meridional transient heat transport depending on the latitude. The transient heat transport can almost entirely be attributed to advective processes. Stirring of heat induced by coherent eddies accounts for the majority of meridional heat transport by these eddies. The majority of the heat transport across the ice edge by all transient processes occurs below the mixed layer and about two thirds of this heat is then upwelled across the base of the winter mixed layer with 40-50% of this heat being brought by coherent eddies. Within the mixed layer, the importance of these eddies for the vertical heat transport towards the pack ice is comparatively smaller at 20-30%., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

33. Set-valued State Estimation Using Hybrid Zonotopes

Author

Siefert, Jacob A., Thompson, Andrew F., Glunt, Jonah J., and Pangborn, Herschel C.

Subjects
FOS: Electrical engineering, electronic engineering, information engineering, Systems and Control (eess.SY), Electrical Engineering and Systems Science - Systems and Control
Abstract

This paper proposes methods for set-valued state estimation of nonlinear, discrete-time systems with nonlinear measurements. This is achieved by combining a novel construct called the input-output set, which approximates system dynamics and measurements, with the hybrid zonotope set representation that can efficiently represent nonconvex and disjoint sets. The methods leverage existing approaches for approximation of nonlinear functions including special ordered set approximations and neural networks. A numerical example demonstrates the proposed method with comparison to a convex approach., Comment: arXiv admin note: text overlap with arXiv:2304.06827

Published
2023
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35. Wind work at the air-sea interface: a modeling study in anticipation of future space missions

Author

Torres, Hector S., primary, Klein, Patrice, additional, Wang, Jinbo, additional, Wineteer, Alexander, additional, Qiu, Bo, additional, Thompson, Andrew F., additional, Renault, Lionel, additional, Rodriguez, Ernesto, additional, Menemenlis, Dimitris, additional, Molod, Andrea, additional, Hill, Christopher N., additional, Strobach, Ehud, additional, Zhang, Hong, additional, Flexas, Mar, additional, and Perkovic-Martin, Dragana, additional

Published
2022
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36. Atmospheric circulation and surface observations [in 'State of the Climate in 2021']

Author

Clem, Kyle R., Raphael, Marilyn N., Adusumilli, Susheel, Baiman, Rebecca, Banwell, Alison F., Barreira, Sandra, Beadling, Rebecca L., Colwell, Steve, Coy, Lawrence, Datta, Rajashree T., De Laat, Jos, Dunmire, Devon, Fogt, Ryan L., Freeman, Natalie M., Fricker, Helen Amanda, Gardner, Alex S., Johnson, Bryan, Keller, Linda M., Kramarova, Natalya A., Lazzara, Matthew A., Lieser, Jan L., MacFerrin, Michael, MacGilchrist, Graeme A., MacLennan, Michelle L., Massom, Robert A., Mazloff, Matthew R., Mote, Thomas L., Nash, Eric R., Newman, Paul A., Norton, Taylor, Petropavlovskikh, Irina, Pitts, Michael, Reid, Phillip, Santee, Michelle L., Scambos, Ted A., Shi, Jia-Rui, Stammerjohn, Sharon, Strahan, Susan E., Thompson, Andrew F., Wille, Jonathan D., and Wilson, Earle

Published
2022

38. Antarctica and the Southern Ocean

Author

Clem, Kyle R., primary, Raphael, Marilyn N., additional, Adusumilli, Susheel, additional, Baiman, Rebecca, additional, Banwell, Alison F., additional, Barreira, Sandra, additional, Beadling, Rebecca L., additional, Colwell, Steve, additional, Coy, Lawrence, additional, Datta, Rajashree T., additional, De Laat, Jos, additional, Dunmire, Devon, additional, Fogt, Ryan L., additional, Freeman, Natalie M., additional, Fricker, Helen Amanda, additional, Gardner, Alex S., additional, Johnson, Bryan, additional, Keller, Linda M., additional, Kramarova, Natalya A., additional, Lazzara, Matthew A., additional, Lieser, Jan L., additional, MacFerrin, Michael, additional, MacGilchrist, Graeme A., additional, MacLennan, Michelle L., additional, Massom, Robert A., additional, Mazloff, Matthew R., additional, Mote, Thomas L., additional, Nash, Eric R., additional, Newman, Paul A., additional, Norton, Taylor, additional, Petropavlovskikh, Irina, additional, Pitts, Michael, additional, Reid, Phillip, additional, Santee, Michelle L., additional, Scambos, Ted A., additional, Shi, Jia-Rui, additional, Stammerjohn, Sharon, additional, Strahan, Susan E., additional, Thompson, Andrew F., additional, Wille, Jonathan D., additional, and Wilson, Earle, additional

Published
2022
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44. Exploration of Icy Ocean Worlds Using Geophysical Approaches

Author

Marusiak, Angela G, primary, Vance, Steven, additional, Panning, Mark P, additional, Běhounková, Marie, additional, Byrne, Paul K, additional, Choblet, Gaël, additional, Daswani, Mohit Melwani, additional, Hughson, Kynan, additional, Journaux, Baptiste, additional, Lobo, Ana H, additional, Schmidt, Britney E, additional, Pleiner Sládková, Kateřina, additional, Soderlund, Krista M, additional, Song, WenZhan, additional, Souček, Ondřej, additional, Steinbrügge, Gregor, additional, Thompson, Andrew F., additional, and Wang, Sili, additional

Published
2021
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46. Two-layer baroclinic eddy heat fluxes: zonal flows and energy balance

Author

Thompson, Andrew F. and Young, William R.

Subjects
Eddies -- Observations, Atmospheric circulation -- Research, Air jets -- Mechanical properties, Earth sciences, Science and technology
Abstract

The eddy heat flux generated by statistically equilibrated baroclinic turbulence supported on a uniform, horizontal temperature gradient is examined using a two-layer [beta]-plane quasigeostrophic model. The dependence of the eddy diffusivity of temperature, [D.sub.[tau]], on external parameters such as [beta], bottom friction [kappa], the deformation radius [lambda], and the velocity jump 2U, is provided by numerical simulations at 110 different points in the parameter space [[beta].sub.*] = [beta][[lambda].sup.1]/U and [[kappa].sub.*] = [kappa][lambda]/U. There is a special 'pivot' value of [[beta].sub.*], [[beta].sup.piv.sub.*] [approximately equal to] 11/16, at which [D.sub.[tau]] depends weakly on [[kappa].sub.*]. But otherwise [D.sub.[tau]] has a complicated dependence on both [[beta].sub.*], and [[kappa].sub.*], highlighted by the fact that reducing K, leads to increases (decreases) in [D.sub.[tau]] if [beta] is less than (greater than) [[beta].sup.piv.sub.*]. Existing heat-flux parameterizafions, based on Kolmogorov cascade theories, predict that [D.sub.[tau]] is nonzero and independent of [[kappa].sub.*] in the limit [[kappa].sub.*] [right arrow] 0. Simulations show indications of this regime provided that [[kappa].sub.*] [less than or equal to] 0.04 and 0.25 [less than or equal to] [[beta].sub.*], [less than or equal to]0.5. All important length scales in this problem, namely the mixing length, the scale of the energy containing eddies, the Rhines scale, and the spacing of the zonal jets, converge to a common value as bottom friction is reduced. The mixing length and jet spacing do not decouple in the parameter regime considered here, as predicted by cascade theories. The convergence of these length scales is due to the formation of jet-scale eddies that align along the eastward jets. The baroclinic component of these eddies helps force the zonal mean flow, which occurs through nonzero Reynolds stress correlations in the upper layer, as opposed to the barotropic mode. This behavior suggests that the dynamics of the inverse barotropic cascade are insufficient to fully describe baroclinic turbulence.

Published
2007

47. Atlantic Ocean Heat Transport Enabled by Indo-Pacific Heat Uptake and Mixing

Author

Holmes, Ryan M., Zika, Jan D., Ferrari, Raffaele, Thompson, Andrew F., Newsom, Emily R., and England, Matthew H.

Abstract

The ocean transports vast amounts of heat around the planet, helping to regulate regional climate. One important component of this heat transport is the movement of warm water from equatorial regions toward the poles, with colder water flowing in return. Here, we introduce a framework relating meridional heat transport to the diabatic processes of surface forcing and turbulent mixing that move heat across temperature classes. Applied to a (1/4)° global ocean model the framework highlights the role of the tropical Indo‐Pacific in the global ocean heat transport. A large fraction of the northward heat transport in the Atlantic is ultimately sourced from heat uptake in the eastern tropical Pacific. Turbulent mixing moves heat from the warm, shallow Indo‐Pacific circulation to the cold deeper‐reaching Atlantic circulation. Our results underscore a renewed focus on the tropical oceans and their role in global circulation pathways.

Published
2019

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