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Your search keyword '"THOMPSON, ANDREW F."' showing total 131 results
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131 results on '"THOMPSON, ANDREW F."'

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. Assessment of oceanographic conditions during the North Atlantic EXport processes in the ocean from RemoTe sensing (EXPORTS) field campaign

Author

Johnson, Leah, Siegel, David A., Thompson, Andrew F., Fields, Erik, Erickson, Zachary K., Cetinic, Ivona, Lee, Craig M., D'Asaro, Eric A., Nelson, Norman B., Omand, Melissa M., Sten, Michaela, Traylor, Shawnee, Nicholson, David P., Graff, Jason R., Steinberg, Deborah K., Sosik, Heidi M., Buesseler, Ken O., Brzezinski, Mark A., Ramos, Inia Soto, Carvalho, Filipa, and Henson, Stephanie A.

Published
2024
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7. EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) North Atlantic sensor calibration and intercalibration documents

Author

Siegel, David A., primary, Cetinic, Ivona, additional, Thompson, Andrew F., additional, Nelson, Norman B., additional, Sten, Michaela, additional, Omand, Melissa, additional, Traylor, Shawnee, additional, Nicholson, David, additional, D’Asaro, Eric, additional, Zhang, Xiaodong, additional, Erickson, Zachary K., additional, Johnson, Leah, additional, and Soto Ramos, Inia M., additional

Published
2023
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10. List of contributors

Author

Abernathey, Ryan, primary, Brearley, J. Alexander, additional, Couespel, Damien, additional, de Lavergne, Casimir, additional, Fer, Ilker, additional, Fox-Kemper, Baylor, additional, Frajka-Williams, Eleanor, additional, Gille, Sarah T., additional, Gnanadesikan, Anand, additional, Groeskamp, Sjoerd, additional, Gula, Jonathan, additional, Hallberg, Robert, additional, Johnson, Helen L., additional, Johnson, Leah, additional, Kelly, Samuel, additional, Lachkar, Zouhair, additional, Lenn, Yueng-Djern, additional, Lévy, Marina, additional, MacKinnon, Jennifer A., additional, Mahadevan, Amala, additional, Marshall, David P., additional, McDougall, Trevor J., additional, Melet, Angélique V., additional, Meredith, Michael, additional, Moum, James N., additional, Musgrave, Ruth, additional, Nash, Jonathan D., additional, Natarov, Andrei, additional, Naveira Garabato, Alberto, additional, Nikurashin, Maxim, additional, Palter, Jaime B., additional, Pollmann, Friederike, additional, Polzin, Kurt L., additional, Pradal, Marie-Aude, additional, Qiao, Fangli, additional, Resplandy, Laure, additional, Richards, Kelvin J., additional, Shcherbina, Andrey, additional, Sheen, Katy L., additional, Shroyer, Emily L., additional, Smyth, William D., additional, Sundermeyer, Miles A., additional, Swart, Sebastiaan, additional, Taylor, John, additional, Thomas, Leif N., additional, Thompson, Andrew F., additional, Timmermans, Mary-Louise, additional, Whalen, Caitlin B., additional, Zhai, Xiaoming, additional, and Zika, Jan, additional

Published
2022
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15. Pathways of Inter‐Basin Exchange From the Bellingshausen Sea to the Amundsen Sea.

Author

Flexas, M. Mar, Thompson, Andrew F., Robertson, Megan L., Speer, Kevin, Sheehan, Peter M. F., and Heywood, Karen J.

Subjects
MELTWATER, ICE shelves, OCEAN temperature, CONTINENTAL slopes, WATER masses, ANTARCTIC ice, GLIDERS (Aeronautics), HYDROGRAPHY
Abstract

The West Antarctic Ice Sheet is experiencing rapid thinning of its floating ice shelves, largely attributed to oceanic basal melt. Numerical models suggest that the Bellingshausen Sea has a key role in setting water properties in the Amundsen Sea and further downstream. Yet, observations confirming these pathways of volume and tracer exchange between coast and shelf break and their impact on inter‐sea exchange remain sparse. Here we analyze the circulation and distribution of glacial meltwater at the boundary between the Bellingshausen Sea and the Amundsen Sea using a combination of glider observations from January 2020 and hydrographic data from instrumented seals. Meltwater distributions over previously unmapped western regions of the continental shelf and slope reveal two distinct meltwater cores with different optical backscatter properties. At Belgica Trough, a subsurface meltwater peak is linked with hydrographic properties from Venable Ice Shelf. West of Belgica Trough, the vertical structure of meltwater concentration changes, with peak values occurring at greater depths and denser isopycnals. Hydrographic analysis suggests that the western (deep) meltwater core is supplied from the eastern part of Abbot Ice Shelf, and is exported to the shelf break via a previously‐overlooked bathymetric trough (here named Seal Trough). Hydrographic sections constructed from seal data reveal that the Antarctic Coastal Current extends west past Belgica Trough, delivering meltwater to the Amundsen Sea. Each of these circulation elements has distinct dynamical implications for the evolution of ice shelves and water masses both locally and downstream, in the Amundsen Sea and beyond. Plain Language Summary: Floating ice shelves in West Antarctica are thinning, which is largely due to melting of the ice shelf base by the ocean. Here, measurements of ocean temperature, salinity, and dissolved oxygen, collected by a remotely‐controlled underwater vehicle (a glider), are used to estimate the amount of ice shelf meltwater released in the Bellingshausen Sea. Distinct cores of meltwater can be distinguished by the amount of suspended material that is present in the water, which we attribute to meltwater following different circulation pathways after entering the ocean. Historical data from seals equipped with temperature and salinity sensors provide additional information about how the meltwater circulates in the region. The seal data show the presence of a narrow coastal current that brings meltwater from the Bellingshausen Sea into the Amundsen Sea. The pathways of meltwater revealed in this study suggest an important influence of the Bellingshausen Sea on ice shelves throughout West Antarctica. Key Points: Hydrographic observations identify both shelf‐break and coastal meltwater pathways from the western Bellingshausen Sea into the Amundsen SeaDifferences in optical backscatter properties associated with meltwater are related to distinct coast‐to‐shelf break pathwaysThe main pathway to the shelf break is via Seal Trough, identified as the de facto western boundary of the Bellingshausen Sea [ABSTRACT FROM AUTHOR]

Published
2024
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16. 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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18. Assessment of Oceanographic Conditions during the North Atlantic EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) Field Campaign

Author

Johnson, Leah, primary, Siegel, David A., additional, Thompson, Andrew F., additional, Fields, Erik, additional, Erickson, Zachary, additional, Cetinic, Ivona, additional, Lee, Craig M., additional, D'Asaro, Eric, additional, Nelson, Norman B., additional, Omand, Melissa, additional, Sten, Michaela, additional, Traylor, Shawnee, additional, Nicholson, David, additional, Graff, Jason R., additional, Steinberg, Deborah, additional, Sosik, Heidi M., additional, Buesseler, Ken, additional, Brzezinski, Mark, additional, Soto Ramos, Inia, additional, Carvalho, Filipa, additional, and Henson, Stephanie, additional

Published
2023
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22. 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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24. 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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29. 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

30. 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

31. 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

32. 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. The Southern Ocean mixed layer and its boundary fluxes: fine-scale observational progress and future research priorities

Author

Swart, Sebastiaan, primary, du Plessis, Marcel D., additional, Nicholson, Sarah-Anne, additional, Monteiro, Pedro M. S., additional, Dove, Lilian A., additional, Thomalla, Sandy, additional, Thompson, Andrew F., additional, Biddle, Louise C., additional, Edholm, Johan M., additional, Giddy, Isabelle, additional, Heywood, Karen J., additional, Lee, Craig, additional, Mahadevan, Amala, additional, Shilling, Geoff, additional, and de Souza, Ronald Buss, additional

Published
2023
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39. 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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41. 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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43. 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

47. 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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49. 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, WESTERLIES, EL Nino, SEA ice, OCEANIC mixing
Abstract

Antarctic sea ice gradually increased from the late 1970s until 2016, when it experienced an abrupt decline. A number of mechanisms have been proposed for both the gradual increase and abrupt decline of Antarctic sea ice, 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 spatial-temporal 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. This mode is associated with periods of abrupt Antarctic sea-ice decline and is related to a weakening of the circumpolar westerlies, which favors surface warming through a shoaling of the ocean mixed layer and decreased northward Ekman heat convergence. Broadly, these results suggest that climate model biases in long-term Antarctic sea-ice and global sea-surface temperature trends are related to each other and that eastern Pacific ENSO variability causes abrupt sea ice changes. [ABSTRACT FROM AUTHOR]

Published
2023
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