Fox-Kemper Baylor

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  • Article
    Wind-driven barotropic gyre I : circulation control by eddy vorticity fluxes to an enhanced removal region
    (Sears Foundation for Marine Research, 2004-03) Fox-Kemper, Baylor ; Pedlosky, Joseph
    It is well known that the barotropic, wind-driven, single-gyre ocean model reaches an inertially-dominated equilibrium with unrealistic circulation strength when the explicit viscosity is reduced to realistically low values. It is shown here that the overall circulation strength can be controlled nonlocally by retaining thin regions of enhanced viscosity parameterizing the effects of increased mixing and topographic interaction near the boundaries. The control is possible even when the inertial boundary layer width is larger than the enhanced viscosity region, as eddy fluxes of vorticity from the interior transport vorticity across the mean streamlines of the inertial boundary current to the frictional region. In relatively inviscid calculations the eddies are the major means of flux across interior mean streamlines.
  • Article
    Saildrone: adaptively sampling the marine environment
    (American Meteorological Society, 2020-06-01) Gentemann, Chelle L. ; Scott, Joel P. ; Mazzini, Piero L. F. ; Pianca, Cassia ; Akella, Santha ; Minnett, Peter J. ; Cornillon, Peter ; Fox-Kemper, Baylor ; Cetinić, Ivona ; Chin, T. Mike ; Gomez-Valdes, Jose ; Vazquez-Cuervo, Jorge ; Tsontos, Vardis ; Yu, Lisan ; Jenkins, Richard ; De Halleux, Sebastien ; Peacock, David ; Cohen, Nora
    From 11 April to 11 June 2018 a new type of ocean observing platform, the Saildrone surface vehicle, collected data on a round-trip, 60-day cruise from San Francisco Bay, down the U.S. and Mexican coast to Guadalupe Island. The cruise track was selected to optimize the science team’s validation and science objectives. The validation objectives include establishing the accuracy of these new measurements. The scientific objectives include validation of satellite-derived fluxes, sea surface temperatures, and wind vectors and studies of upwelling dynamics, river plumes, air–sea interactions including frontal regions, and diurnal warming regions. On this deployment, the Saildrone carried 16 atmospheric and oceanographic sensors. Future planned cruises (with open data policies) are focused on improving our understanding of air–sea fluxes in the Arctic Ocean and around North Brazil Current rings.
  • Article
    Wind-driven barotropic gyre II : effects of eddies and low interior viscosity
    (Sears Foundation for Marine Research, 2004-03) Fox-Kemper, Baylor
    Using boundary-enhanced viscosity to control the mean circulation, a simple model can be created and used for study of strong inertial effects in a western-intensified calculation. The simplicity allows for a greater number of strongly-inertial numerical experiments than computationally feasible in a general circulation model. This paper is an introduction to the behavior of this model, covering its general features. Some of the inertial phenomena, including the primary balances of the boundary current and basin interior, the temporal behavior, and the changes in the mean state across parameter space are presented. The analysis of these phenomena focuses on the effects of eddies and the type of eddies present. The low interior viscosity allows for more pronounced eddy effects. As this model is intended for use in future studies, many of the diagnostic tools found to be useful here are likely to be reused effectively.
  • Article
    Ocean climate observing requirements in support of climate research and climate information
    (Frontiers Media, 2019-07-31) Stammer, Detlef ; Bracco, Annalisa ; AchutaRao, Krishna ; Beal, Lisa M. ; Bindoff, Nathaniel L. ; Braconnot, Pascale ; Cai, Wenju ; Chen, Dake ; Collins, Matthew ; Danabasoglu, Gokhan ; Dewitte, Boris ; Farneti, Riccardo ; Fox-Kemper, Baylor ; Fyfe, John ; Griffies, Stephen M. ; Jayne, Steven R. ; Lazar, Alban ; Lengaigne, Matthieu ; Lin, Xiaopei ; Marsland, Simon ; Minobe, Shoshiro ; Monteiro, Pedro M. S. ; Robinson, Walter ; Roxy, Mathew Koll ; Rykaczewski, Ryan R. ; Speich, Sabrina ; Smith, Inga J. ; Solomon, Amy ; Storto, Andrea ; Takahashi, Ken ; Toniazzo, Thomas ; Vialard, Jérôme
    Natural variability and change of the Earth’s climate have significant global societal impacts. With its large heat and carbon capacity and relatively slow dynamics, the ocean plays an integral role in climate, and provides an important source of predictability at seasonal and longer timescales. In addition, the ocean provides the slowly evolving lower boundary to the atmosphere, driving, and modifying atmospheric weather. Understanding and monitoring ocean climate variability and change, to constrain and initialize models as well as identify model biases for improved climate hindcasting and prediction, requires a scale-sensitive, and long-term observing system. A climate observing system has requirements that significantly differ from, and sometimes are orthogonal to, those of other applications. In general terms, they can be summarized by the simultaneous need for both large spatial and long temporal coverage, and by the accuracy and stability required for detecting the local climate signals. This paper reviews the requirements of a climate observing system in terms of space and time scales, and revisits the question of which parameters such a system should encompass to meet future strategic goals of the World Climate Research Program (WCRP), with emphasis on ocean and sea-ice covered areas. It considers global as well as regional aspects that should be accounted for in designing observing systems in individual basins. Furthermore, the paper discusses which data-driven products are required to meet WCRP research and modeling needs, and ways to obtain them through data synthesis and assimilation approaches. Finally, it addresses the need for scientific capacity building and international collaboration in support of the collection of high-quality measurements over the large spatial scales and long time-scales required for climate research, bridging the scientific rational to the required resources for implementation.
  • Article
    Mean biases, variability, and trends in air–sea fluxes and sea surface temperature in the CCSM4
    (American Meteorological Society, 2012-11-15) Bates, Susan C. ; Fox-Kemper, Baylor ; Jayne, Steven R. ; Large, William G. ; Stevenson, Samantha ; Yeager, Stephen G.
    Air–sea fluxes from the Community Climate System Model version 4 (CCSM4) are compared with the Coordinated Ocean-Ice Reference Experiment (CORE) dataset to assess present-day mean biases, variability errors, and late twentieth-century trend differences. CCSM4 is improved over the previous version, CCSM3, in both air–sea heat and freshwater fluxes in some regions; however, a large increase in net shortwave radiation into the ocean may contribute to an enhanced hydrological cycle. The authors provide a new baseline for assessment of flux variance at annual and interannual frequency bands in future model versions and contribute a new metric for assessing the coupling between the atmospheric and oceanic planetary boundary layer (PBL) schemes of any climate model. Maps of the ratio of CCSM4 variance to CORE reveal that variance on annual time scales has larger error than on interannual time scales and that different processes cause errors in mean, annual, and interannual frequency bands. Air temperature and specific humidity in the CCSM4 atmospheric boundary layer (ABL) follow the sea surface conditions much more closely than is found in CORE. Sensible and latent heat fluxes are less of a negative feedback to sea surface temperature warming in the CCSM4 than in the CORE data with the model’s PBL allowing for more heating of the ocean’s surface.
  • Article
    Reevaluating the roles of eddies in multiple barotropic wind-driven gyres
    (American Meteorological Society, 2005-07) Fox-Kemper, Baylor
    Multiple-gyre ocean models have a weaker mean subtropical circulation than single-gyre calculations with the same viscosity and subtropical forcing. Traditionally, this reduction in circulation is attributed to an intergyre eddy vorticity flux that cancels some of the wind input, part of which does not require a Lagrangian mass exchange (theory of dissipative meandering). Herein the intergyre eddy vorticity flux is shown to be a controlling factor in barotropic models at high Reynolds number only with exactly antisymmetric gyres and slip boundary conditions. Almost no intergyre flux occurs when no-slip boundary conditions are used, yet the subtropical gyre is still significantly weaker in multiple-gyre calculations. Sinuous modes of instability present only in multiple gyres are shown here to vastly increase the eddy vorticity transport efficiency. This increase in efficiency reduces the mean circulation necessary for equilibrium. With slip boundary conditions, the intergyre eddy transport is possibly much larger. However, with wind forcing relevant for the ocean—two unequal gyres—a mean flow flux of vorticity rather than an eddy flux between the regions of opposing wind forcing is increasingly important with increasing Reynolds number. A physical rationalization of the differing results is provided by diagnosis of the equilibrium vorticity budget and eddy transport efficiency. Calculations varying 1) boundary conditions, 2) sources and sinks of vorticity, 3) eddy transport efficiency, and 4) the degree of symmetry of the gyres are discussed.
  • Article
    NeverWorld2: an idealized model hierarchy to investigate ocean mesoscale eddies across resolutions
    (European Geosciences Union, 2022-09-01) Marques, Gustavo ; Loose, Nora ; Yankovsky, Elizabeth ; Steinberg, Jacob M. ; Chang, Chiung-Yin ; Bhamidipati, Neeraja ; Adcroft, Alistair ; Fox-Kemper, Baylor ; Griffies, Stephen M. ; Hallberg, Robert ; Jansen, Malte F. ; Khatri, Hemant ; Zanna, Laure
    We describe an idealized primitive-equation model for studying mesoscale turbulence and leverage a hierarchy of grid resolutions to make eddy-resolving calculations on the finest grids more affordable. The model has intermediate complexity, incorporating basin-scale geometry with idealized Atlantic and Southern oceans and with non-uniform ocean depth to allow for mesoscale eddy interactions with topography. The model is perfectly adiabatic and spans the Equator and thus fills a gap between quasi-geostrophic models, which cannot span two hemispheres, and idealized general circulation models, which generally include diabatic processes and buoyancy forcing. We show that the model solution is approaching convergence in mean kinetic energy for the ocean mesoscale processes of interest and has a rich range of dynamics with circulation features that emerge only due to resolving mesoscale turbulence.
  • Thesis
    Eddies and friction : removal of vorticity from the wind-driven gyre
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2003-06) Fox-Kemper, Baylor
    Inertial terms dominate the single-gyre ocean model and prevent western-intensification when the viscosity is small. This occurs long before the oceanically-appropriate parameter range. It is demonstrated here that the circulation is controlled if a mechanism for ultimate removal of vorticity exists, even if it is active only in a narrow region near the boundary. Vorticity removal is modeled here as a viscosity enhanced very near the solid boundaries to roughly parameterize missing boundary physics like topographic interaction and three dimensional turbulence over the shelf. This boundary-enhanced viscosity allows western-intensified mean flows even when the inertial boundary width, is much wider than the frictional region because eddies flux vorticity from within the interior streamlines to the frictional region for removal. Using boundary-enhanced viscosity, western-intensified calculations are possible with lower interior viscosity than in previous studies. Interesting behaviors result: a boundary-layer balance novel to the model, calculations with promise for eddy parameterization, eddy-driven gyres rotating opposite the wind, and temporal complexity including basin resonances. I also demonstrate that multiple-gyre calculations have weaker mean circulation than single-gyres with the same viscosity and subtropical forcing. Despite traditional understanding, almost no inter-gyre flux occurs if no-slip boundary conditions are used. The inter-gyre eddy flux is in control only with exactly symmetric gyres and free slip boundaries. Even without the inter-gyre flux, the multiple-gyre circulation is weak because of sinuous instabilities on the jet which are not present in the single-gyre model. These modes efficiently flux vorticity to the boundary and reduce the circulation without an inter-gyre flux, postponing inertial domination to much smaller viscosities. Then sinuous modes in combination with boundary-enhanced viscosity can control the circulation.
  • Article
    SEASTAR: A mission to study ocean submesoscale dynamics and small-scale atmosphere-ocean processes in coastal, shelf and polar seas
    (Frontiers Media, 2019-08-13) Gommenginger, Christine ; Chapron, Bertrand ; Hogg, Andy ; Buckingham, Christian ; Fox-Kemper, Baylor ; Eriksson, Leif ; Soulat, Francois ; Ubelmann, Clement ; Ocampo-Torres, Francisco ; Nardelli, Bruno Buongiorno ; Griffin, David ; Lopez-Dekker, Paco ; Knudsen, Per ; Andersen, Ole ; Stenseng, Lars ; Stapleton, Neil ; Perrie, Will ; Violante-Carvalho, Nelson ; Schulz-Stellenfleth, Johannes ; Woolf, David K. ; Isern-Fontanet, Jordi ; Ardhuin, Fabrice ; Klein, Patrice ; Mouche, Alexis ; Pascual, Ananda ; Capet, Xavier ; Hauser, Daniele ; Stoffelen, Ad ; Morrow, Rosemary ; Aouf, Lotfi ; Breivik, Øyvind ; Fu, Lee-Lueng ; Johannessen, Johnny A. ; Aksenov, Yevgeny ; Bricheno, Lucy ; Hirschi, Joel ; Martin, Adrien C. H. ; Martin, Adrian P. ; Nurser, A. J. George ; Polton, Jeff ; Wolf, Judith ; Johnsen, Harald ; Soloviev, Alexander ; Jacobs, Gregg A. ; Collard, Fabrice ; Groom, Steve ; Kudryavtsev, Vladimir ; Wilkin, John L. ; Navarro, Victor ; Babanin, Alexander ; Martin, Matthew ; Siddorn, John ; Saulter, Andrew ; Rippeth, Tom P. ; Emery, Bill ; Maximenko, Nikolai ; Romeiser, Roland ; Graber, Hans C. ; Alvera Azcarate, Aida ; Hughes, Chris W. ; Vandemark, Douglas ; da Silva, Jose ; Van Leeuwen, Peter Jan ; Naveira Garabato, Alberto C. ; Gemmrich, Johannes ; Mahadevan, Amala ; Marquez, Jose ; Munro, Yvonne ; Doody, Sam ; Burbidge, Geoff
    High-resolution satellite images of ocean color and sea surface temperature reveal an abundance of ocean fronts, vortices and filaments at scales below 10 km but measurements of ocean surface dynamics at these scales are rare. There is increasing recognition of the role played by small scale ocean processes in ocean-atmosphere coupling, upper-ocean mixing and ocean vertical transports, with advanced numerical models and in situ observations highlighting fundamental changes in dynamics when scales reach 1 km. Numerous scientific publications highlight the global impact of small oceanic scales on marine ecosystems, operational forecasts and long-term climate projections through strong ageostrophic circulations, large vertical ocean velocities and mixed layer re-stratification. Small-scale processes particularly dominate in coastal, shelf and polar seas where they mediate important exchanges between land, ocean, atmosphere and the cryosphere, e.g., freshwater, pollutants. As numerical models continue to evolve toward finer spatial resolution and increasingly complex coupled atmosphere-wave-ice-ocean systems, modern observing capability lags behind, unable to deliver the high-resolution synoptic measurements of total currents, wind vectors and waves needed to advance understanding, develop better parameterizations and improve model validations, forecasts and projections. SEASTAR is a satellite mission concept that proposes to directly address this critical observational gap with synoptic two-dimensional imaging of total ocean surface current vectors and wind vectors at 1 km resolution and coincident directional wave spectra. Based on major recent advances in squinted along-track Synthetic Aperture Radar interferometry, SEASTAR is an innovative, mature concept with unique demonstrated capabilities, seeking to proceed toward spaceborne implementation within Europe and beyond.
  • Article
    Ocean mesoscale and frontal-scale ocean–atmosphere interactions and influence on large-scale climate: a review
    (American Meteorological Society, 2023-03-01) Seo, Hyodae ; O’Neill, Larry W. ; Bourassa, Mark A. ; Czaja, Arnaud ; Drushka, Kyla ; Edson, James B. ; Fox-Kemper, Baylor ; Frenger, Ivy ; Gille, Sarah T. ; Kirtman, Benjamin P. ; Minobe, Shoshiro ; Pendergrass, Angeline G. ; Renault, Lionel ; Roberts, Malcolm J. ; Schneider, Niklas ; Small, R. Justin ; Stoffelen, Ad ; Wang, Qing
    Abstract Two decades of high-resolution satellite observations and climate modeling studies have indicated strong ocean–atmosphere coupled feedback mediated by ocean mesoscale processes, including semipermanent and meandrous SST fronts, mesoscale eddies, and filaments. The air–sea exchanges in latent heat, sensible heat, momentum, and carbon dioxide associated with this so-called mesoscale air–sea interaction are robust near the major western boundary currents, Southern Ocean fronts, and equatorial and coastal upwelling zones, but they are also ubiquitous over the global oceans wherever ocean mesoscale processes are active. Current theories, informed by rapidly advancing observational and modeling capabilities, have established the importance of mesoscale and frontal-scale air–sea interaction processes for understanding large-scale ocean circulation, biogeochemistry, and weather and climate variability. However, numerous challenges remain to accurately diagnose, observe, and simulate mesoscale air–sea interaction to quantify its impacts on large-scale processes. This article provides a comprehensive review of key aspects pertinent to mesoscale air–sea interaction, synthesizes current understanding with remaining gaps and uncertainties, and provides recommendations on theoretical, observational, and modeling strategies for future air–sea interaction research. Significance Statement Recent high-resolution satellite observations and climate models have shown a significant impact of coupled ocean–atmosphere interactions mediated by small-scale (mesoscale) ocean processes, including ocean eddies and fronts, on Earth’s climate. Ocean mesoscale-induced spatial temperature and current variability modulate the air–sea exchanges in heat, momentum, and mass (e.g., gases such as water vapor and carbon dioxide), altering coupled boundary layer processes. Studies suggest that skillful simulations and predictions of ocean circulation, biogeochemistry, and weather events and climate variability depend on accurate representation of the eddy-mediated air–sea interaction. However, numerous challenges remain in accurately diagnosing, observing, and simulating mesoscale air–sea interaction to quantify its large-scale impacts. This article synthesizes the latest understanding of mesoscale air–sea interaction, identifies remaining gaps and uncertainties, and provides recommendations on strategies for future ocean–weather–climate research.
  • Article
    Integrated observations of global surface winds, currents, and waves: Requirements and challenges for the next decade
    (Frontiers Media, 2019-07-24) Villas Bôas, Ana B. ; Ardhuin, Fabrice ; Ayet, Alex ; Bourassa, Mark A. ; Brandt, Peter ; Chapron, Bertrand ; Cornuelle, Bruce D. ; Farrar, J. Thomas ; Fewings, Melanie R. ; Fox-Kemper, Baylor ; Gille, Sarah T. ; Gommenginger, Christine ; Heimbach, Patrick ; Hell, Momme C. ; Li, Qing ; Mazloff, Matthew R. ; Merrifield, Sophia T. ; Mouche, Alexis ; Rio, Marie H. ; Rodriguez, Ernesto ; Shutler, Jamie D. ; Subramanian, Aneesh C. ; Terrill, Eric ; Tsamados, Michel ; Ubelmann, Clement ; van Sebille, Erik
    Ocean surface winds, currents, and waves play a crucial role in exchanges of momentum, energy, heat, freshwater, gases, and other tracers between the ocean, atmosphere, and ice. Despite surface waves being strongly coupled to the upper ocean circulation and the overlying atmosphere, efforts to improve ocean, atmospheric, and wave observations and models have evolved somewhat independently. From an observational point of view, community efforts to bridge this gap have led to proposals for satellite Doppler oceanography mission concepts, which could provide unprecedented measurements of absolute surface velocity and directional wave spectrum at global scales. This paper reviews the present state of observations of surface winds, currents, and waves, and it outlines observational gaps that limit our current understanding of coupled processes that happen at the air-sea-ice interface. A significant challenge for the coming decade of wind, current, and wave observations will come in combining and interpreting measurements from (a) wave-buoys and high-frequency radars in coastal regions, (b) surface drifters and wave-enabled drifters in the open-ocean, marginal ice zones, and wave-current interaction “hot-spots,” and (c) simultaneous measurements of absolute surface currents, ocean surface wind vector, and directional wave spectrum from Doppler satellite sensors.