Key publications
Sheen KL, Smith DM, Dunstone NJ, Eade R, Rowell DP, Vellinga M (In Press). Skilful prediction of Sahel summer rainfall on inter-annual and multi-year timescales. Nature Communications
Waterman S, Meyer A, Polzin KL, Naveira Garabato AC, Sheen KL (2021). Antarctic Circumpolar Current Impacts on Internal Wave Life Cycles.
Geophysical Research Letters,
48(8).
Abstract:
Antarctic Circumpolar Current Impacts on Internal Wave Life Cycles
Major gaps exist in our understanding of the pathways between internal wave generation and breaking in the Southern Ocean, with important implications for the distribution of internal wave-driven mixing, the sensitivity of ocean mixing rates and patterns to changes in the ocean environment, and the necessary ingredients of mixing parameterizations. Here we assess the dominant processes in internal wave evolution by characterizing wave and mesoscale flow scales based on full-depth in situ measurements in a Southern Ocean mixing hot spot and a ray tracing calculation. The exercise highlights the importance of Antarctic Circumpolar Current jets as a dominant influence on internal wave life cycles through advection, the modification of wave characteristics via wave-mean flow interactions, and the set-up of critical layers for both upward- and downward-propagating waves. Our findings suggest that it is important to represent mesoscale flow impacts in parameterizations of internal wave-driven mixing in the Southern Ocean.
Abstract.
Sheen K, Gille S, Thompson A, Swart S (2021). Mixing in the Southern Ocean. In Garabato A, Meredith M (Eds.)
Ocean Mixing Drivers, Mechanisms and Impacts, Elsevier, 301-327.
Abstract:
Mixing in the Southern Ocean
Abstract.
Whalen CB, de Lavergne C, Naveira Garabato AC, Klymak JM, MacKinnon JA, Sheen KL (2020). Internal wave-driven mixing: governing processes and consequences for climate. Nature Reviews Earth & Environment, 1(11), 606-621.
Abrahamsen EP, Meijers AJS, Polzin KL, Naveira Garabato AC, King BA, Firing YL, Sallée J-B, Sheen KL, Gordon AL, Huber BA, et al (2019). Stabilization of dense Antarctic water supply to the Atlantic Ocean overturning circulation. Nature Climate Change, 9(10), 742-746.
Dunstone N, Smith D, Scaife A, Hermanson L, Fereday D, O'Reilly C, Stirling A, Eade R, Gordon M, MacLachlan C, et al (2018). Skilful Seasonal Predictions of Summer European Rainfall.
Geophysical Research Letters,
45(7), 3246-3254.
Abstract:
Skilful Seasonal Predictions of Summer European Rainfall
Year-to-year variability in Northern European summer rainfall has profound societal and economic impacts; however, current seasonal forecast systems show no significant forecast skill. Here we show that skillful predictions are possible (r ~0.5, p 80 members) are required for skillful predictions. This work is promising for the development of European summer rainfall climate services.
Abstract.
Publications by category
Journal articles
Sheen KL, Smith DM, Dunstone NJ, Eade R, Rowell DP, Vellinga M (In Press). Skilful prediction of Sahel summer rainfall on inter-annual and multi-year timescales. Nature Communications
Cox I, Brewin RJW, Dall'Olmo G, Sheen K, Sathyendranath S, Rasse R, Ulloa O (2023). Distinct habitat and biogeochemical properties of low‐oxygen‐adapted tropical oceanic phytoplankton.
Limnology and Oceanography,
68(9), 2022-2039.
Abstract:
Distinct habitat and biogeochemical properties of low‐oxygen‐adapted tropical oceanic phytoplankton
AbstractWe use data collected by Biogeochemical Argo (BGC‐Argo) float, over a 5‐year period (2016–2021), to study the dynamics of a unique low‐oxygen‐adapted phytoplanktonic community in the eastern tropical North Pacific. We isolate this community using a model that partitions vertical profiles of chlorophyll a (Chl a) and particulate backscattering into the contributions of three communities of phytoplankton: C1, the community in the mixed‐layer; C2, at the deep Chl a maximum; and C3, in low‐oxygen waters at the base of the euphotic zone. We find that C3 has a similar chl‐specific particulate backscattering to C2, both lower than C1. C2 and C3 contribute significantly to integrated stocks of Chl a, both at around 41%, and both around 30% of integrated particulate backscattering (after removing a background signal attributed to nonalgal particles). Found at depths of around 100 m, the peak biomass of C3 is lower than C2 (located at around 60 m), and yet, C3 makes similar contributions to integrated stocks, because it has a broader peak than C2. In relation to C1 and C2, C3 thrives in a lower temperature, higher density, lower light, lower oxygen, and higher saline habitat. This work illustrates how BGC‐Argo floats, in combination with simple conceptual models, can be used to observe the dynamics of unique communities of phytoplankton in extreme environments. The projected climate‐driven changes in oxygen minimum zones add urgency to understand the vulnerabilities of these communities both in terms of stocks and composition.
Abstract.
Ford DJ, Tilstone GH, Shutler JD, Kitidis V, Sheen KL, Dall’Olmo G, Orselli IBM (2023). Mesoscale Eddies Enhance the Air‐Sea CO<sub>2</sub> Sink in the South Atlantic Ocean.
Geophysical Research Letters,
50(9).
Abstract:
Mesoscale Eddies Enhance the Air‐Sea CO2 Sink in the South Atlantic Ocean
AbstractMesoscale eddies are abundant in the global oceans and known to affect oceanic and atmospheric conditions. Understanding their cumulative impact on the air‐sea carbon dioxide (CO2) flux may have significant implications for the ocean carbon sink. Observations and Lagrangian tracking were used to estimate the air‐sea CO2 flux of 67 long lived (>1 year) mesoscale eddies in the South Atlantic Ocean over a 16 year period. Both anticyclonic eddies originating from the Agulhas retroflection and cyclonic eddies originating from the Benguela upwelling act as net CO2 sinks over their lifetimes. Anticyclonic eddies displayed an exponential decrease in the net CO2 sink, whereas cyclonic eddies showed a linear increase. Combined, these eddies significantly enhanced the CO2 sink into the South Atlantic Ocean by 0.08 ± 0.04%. The studied eddies constitute a fraction of global eddies, and eddy activity is increasing; therefore, explicitly resolving eddies appears critical when assessing the ocean carbon sink.
Abstract.
Gunn KL, Sheen KL, Tang Q (2022). Editorial: Acoustically Mapping the Ocean. Frontiers in Marine Science, 9
Meredith MP, Inall ME, Brearley JA, Ehmen T, Sheen K, Munday D, Cook A, Retallick K, Van Landeghem K, Gerrish L, et al (2022). Internal tsunamigenesis and ocean mixing driven by glacier calving in Antarctica.
Sci Adv,
8(47).
Abstract:
Internal tsunamigenesis and ocean mixing driven by glacier calving in Antarctica.
Ocean mixing around Antarctica exerts key influences on glacier dynamics and ice shelf retreats, sea ice, and marine productivity, thus affecting global sea level and climate. The conventional paradigm is that this is dominated by winds, tides, and buoyancy forcing. Direct observations from the Antarctic Peninsula demonstrate that glacier calving triggers internal tsunamis, the breaking of which drives vigorous mixing. Being widespread and frequent, these internal tsunamis are at least comparable to winds, and much more important than tides, in driving regional shelf mixing. They are likely relevant everywhere that marine-terminating glaciers calve, including Greenland and across the Arctic. Calving frequency may change with higher ocean temperatures, suggesting possible shifts to internal tsunamigenesis and mixing in a warming climate.
Abstract.
Author URL.
Waterman S, Meyer A, Polzin KL, Naveira Garabato AC, Sheen KL (2021). Antarctic Circumpolar Current Impacts on Internal Wave Life Cycles.
Geophysical Research Letters,
48(8).
Abstract:
Antarctic Circumpolar Current Impacts on Internal Wave Life Cycles
Major gaps exist in our understanding of the pathways between internal wave generation and breaking in the Southern Ocean, with important implications for the distribution of internal wave-driven mixing, the sensitivity of ocean mixing rates and patterns to changes in the ocean environment, and the necessary ingredients of mixing parameterizations. Here we assess the dominant processes in internal wave evolution by characterizing wave and mesoscale flow scales based on full-depth in situ measurements in a Southern Ocean mixing hot spot and a ray tracing calculation. The exercise highlights the importance of Antarctic Circumpolar Current jets as a dominant influence on internal wave life cycles through advection, the modification of wave characteristics via wave-mean flow interactions, and the set-up of critical layers for both upward- and downward-propagating waves. Our findings suggest that it is important to represent mesoscale flow impacts in parameterizations of internal wave-driven mixing in the Southern Ocean.
Abstract.
Munoz-Ramirez CP, Beltran-Concha M, Perez-Araneda K, Sands CJ, Barnes DKA, Roman-Gonzalez A, de Lecea AM, Retallick K, van Landeghem K, Sheen K, et al (2021). Genetic variation in the small bivalve Nuculana inaequisculpta along a retreating glacier fjord, King George Island, Antarctica.
REVISTA DE BIOLOGIA MARINA Y OCEANOGRAFIA,
56(2), 151-156.
Author URL.
Fortnam M, Atkins M, Brown K, Chaigneau T, Frouws A, Gwaro K, Huxham M, Kairo J, Kimeli A, Kirui B, et al (2021). Multiple impact pathways of the 2015-2016 El Niño in coastal Kenya.
Ambio,
50(1), 174-189.
Abstract:
Multiple impact pathways of the 2015-2016 El Niño in coastal Kenya.
The 2015-2016 El Niño had large impacts globally. The effects were not as great as anticipated in Kenya, however, leading some commentators to call it a 'non-event'. Our study uses a novel combination of participatory Climate Vulnerability and Capacity Analysis tools, and new and existing social and biophysical data, to analyse vulnerability to, and the multidimensional impacts of, the 2015-2016 El Niño episode in southern coastal Kenya. Using a social-ecological systems lens and a unique dataset, our study reveals impacts overlooked by conventional analysis. We show how El Niño stressors interact with and amplify existing vulnerabilities to differentially impact local ecosystems and people. The policy significance of this finding is that the development of specific national capacities to deal with El Niño events is insufficient; it will be necessary to also address local vulnerabilities to everyday and recurrent stressors and shocks to build resilience to the effects of El Niño and other extremes in climate and weather.
Abstract.
Author URL.
Xiao W, Sheen KL, Tang Q, Shutler J, Hobbs R, Ehmen T (2021). Temperature and Salinity Inverted for a Mediterranean Eddy Captured with Seismic Data, Using a Spatially Iterative Markov Chain Monte Carlo Approach. Frontiers in Marine Science, 8
Wilson DR, Godley BJ, Haggar GL, Santillo D, Sheen KL (2021). The influence of depositional environment on the abundance of microplastic pollution on beaches in the Bristol Channel, UK.
Mar Pollut Bull,
164Abstract:
The influence of depositional environment on the abundance of microplastic pollution on beaches in the Bristol Channel, UK.
Microplastic is a ubiquitous environmental contaminant, but large gaps still exist in our knowledge of its distribution. We conducted a detailed assessment of the extent and variability of microplastic pollution in the Bristol Channel, UK. Sand samples were collected between the 5th and 30th August 2017, with microplastic recovered from 15 of the 16 beaches sampled along a coastal extent of ~230 km. In total, 1446 particles of suspected microplastic were extracted using a cascade of sieves and visual identification. The most common microplastics recovered were fragments (74%) and industrial plastic pellets (13%). We used Fourier-Transform Infrared (FTIR) spectroscopy to analyse 25% of recovered particles, 96.5% of which were confirmed as plastic, with polyethylene (61%) and polypropylene (26%) the most common polymers. Our analysis of local beach environments indicates microplastic burdens were higher on lower energy beaches with finer sediments, highlighting the importance of depositional environment in determining microplastic abundance.
Abstract.
Author URL.
Whalen CB, de Lavergne C, Naveira Garabato AC, Klymak JM, MacKinnon JA, Sheen KL (2020). Internal wave-driven mixing: governing processes and consequences for climate. Nature Reviews Earth & Environment, 1(11), 606-621.
Bascur M, Muñoz-Ramírez C, Román-González A, Sheen K, Barnes DKA, Sands CJ, Brante A, Urzúa Á (2020). The influence of glacial melt and retreat on the nutritional condition of the bivalve Nuculana inaequisculpta (Protobranchia: Nuculanidae) in the West Antarctic Peninsula. PLOS ONE, 15(5), e0233513-e0233513.
Abrahamsen EP, Meijers AJS, Polzin KL, Naveira Garabato AC, King BA, Firing YL, Sallée J-B, Sheen KL, Gordon AL, Huber BA, et al (2019). Stabilization of dense Antarctic water supply to the Atlantic Ocean overturning circulation. Nature Climate Change, 9(10), 742-746.
Dunstone N, Smith D, Scaife A, Hermanson L, Fereday D, O'Reilly C, Stirling A, Eade R, Gordon M, MacLachlan C, et al (2018). Skilful Seasonal Predictions of Summer European Rainfall.
Geophysical Research Letters,
45(7), 3246-3254.
Abstract:
Skilful Seasonal Predictions of Summer European Rainfall
Year-to-year variability in Northern European summer rainfall has profound societal and economic impacts; however, current seasonal forecast systems show no significant forecast skill. Here we show that skillful predictions are possible (r ~0.5, p 80 members) are required for skillful predictions. This work is promising for the development of European summer rainfall climate services.
Abstract.
Clement L, Frajka-Williams E, Sheen KL, Brearley JA, Garabato ACN (2016). Generation of Internal Waves by Eddies Impinging on the Western Boundary of the North Atlantic.
JOURNAL OF PHYSICAL OCEANOGRAPHY,
46(4), 1067-1079.
Author URL.
Smith DM, Booth BBB, Dunstone NJ, Eade R, Hermanson L, Jones GS, Scaife AA, Sheen KL, Thompson V (2016). Role of volcanic and anthropogenic aerosols in the recent global surface warming slowdown. Nature Climate Change, 6(10), 936-940.
Trossman DS, Waterman S, Polzin KL, Arbic BK, Garner ST, Naveira-Garabato AC, Sheen KL (2015). Internal lee wave closures: Parameter sensitivity and comparison to observations.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS,
120(12), 7997-8019.
Author URL.
Sheen KL, Brearley JA, Naveira Garabato AC, Smeed DA, Laurent LS, Meredith MP, Thurnherr AM, Waterman SN (2015). Modification of turbulent dissipation rates by a deep Southern Ocean eddy.
Geophysical Research Letters,
42(9), 3450-3457.
Abstract:
Modification of turbulent dissipation rates by a deep Southern Ocean eddy
AbstractThe impact of a mesoscale eddy on the magnitude and spatial distribution of diapycnal ocean mixing is investigated using a set of hydrographic and microstructure measurements collected in the Southern Ocean. These data sampled a baroclinic, middepth eddy formed during the disintegration of a deep boundary current. Turbulent dissipation is suppressed within the eddy but is elevated by up to an order of magnitude along the upper and lower eddy boundaries. A ray tracing approximation is employed as a heuristic device to elucidate how the internal wave field evolves in the ambient velocity and stratification conditions accompanying the eddy. These calculations are consistent with the observations, suggesting reflection of internal wave energy from the eddy center and enhanced breaking through critical layer processes along the eddy boundaries. These results have important implications for understanding where and how internal wave energy is dissipated in the presence of energetic deep geostrophic flows.
Abstract.
Sarkar S, Sheen KL, Klaeschen D, Brearley JA, Minshull TA, Berndt C, Hobbs RW, Garabato ACN (2015). Seismic reflection imaging of mixing processes in Fram Strait.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS,
120(10), 6884-6896.
Author URL.
Sévellec F, Naveira Garabato AC, Brearley JA, Sheen KL (2015). Vertical Flow in the Southern Ocean Estimated from Individual Moorings.
Journal of Physical Oceanography,
45(9), 2209-2220.
Abstract:
Vertical Flow in the Southern Ocean Estimated from Individual Moorings
AbstractThis study demonstrates that oceanic vertical velocities can be estimated from individual mooring measurements, even for nonstationary flow. This result is obtained under three assumptions: (i) weak diffusion (Péclet number ≫ 1), (ii) weak friction (Reynolds number ≫ 1), and (iii) small inertial terms (Rossby number ≪ 1). The theoretical framework is applied to a set of four moorings located in the Southern Ocean. For this site, the diagnosed vertical velocities are highly variable in time, their standard deviation being one to two orders of magnitude greater than their mean. The time-averaged vertical velocities are demonstrated to be largely induced by geostrophic flow and can be estimated from the time-averaged density and horizontal velocities. This suggests that local time-mean vertical velocities are primarily forced by the time-mean ocean dynamics, rather than by, for example, transient eddies or internal waves. It is also shown that, in the context of these four moorings, the time-mean vertical flow is consistent with stratified Taylor column dynamics in the presence of a topographic obstacle.
Abstract.
Brearley JA, Sheen KL, Naveira Garabato AC, Smeed DA, Speer KG, Thurnherr AM, Meredith MP, Waterman S (2014). Deep boundary current disintegration in Drake Passage. Geophysical Research Letters, 41(1), 121-127.
Sheen KL, Garabato ACN, Brearley JA, Meredith MP, Polzin KL, Smeed DA, Forryan A, King BA, Sallée JB, St. Laurent L, et al (2014). Eddy-induced variability in Southern Ocean abyssal mixing on climatic timescales.
Nature Geoscience,
7(8), 577-582.
Abstract:
Eddy-induced variability in Southern Ocean abyssal mixing on climatic timescales
The Southern Ocean plays a pivotal role in the global ocean circulation and climate. There, the deep water masses of the world ocean upwell to the surface and subsequently sink to intermediate and abyssal depths, forming two overturning cells that exchange substantial quantities of heat and carbon with the atmosphere. The sensitivity of the upper cell to climatic changes in forcing is relatively well established. However, little is known about how the lower cell responds, and in particular whether small-scale mixing in the abyssal Southern Ocean, an important controlling process of the lower cell, is influenced by atmospheric forcing. Here, we present observational evidence that relates changes in abyssal mixing to oceanic eddy variability on timescales of months to decades. Observational estimates of mixing rates, obtained along a repeat hydrographic transect across Drake Passage, are shown to be dependent on local oceanic eddy energy, derived from moored current meter and altimetric measurements. As the intensity of the regional eddy field is regulated by the Southern Hemisphere westerly winds, our findings suggest that Southern Ocean abyssal mixing and overturning are sensitive to climatic perturbations in wind forcing. © 2014 Macmillan Publishers Limited.
Abstract.
Waterman S, Polzin KL, Naveira Garabato AC, Sheen KL, Forryan A (2014). Suppression of Internal Wave Breaking in the Antarctic Circumpolar Current near Topography.
Journal of Physical Oceanography,
44(5), 1466-1492.
Abstract:
Suppression of Internal Wave Breaking in the Antarctic Circumpolar Current near Topography
Abstract
. Simultaneous full-depth microstructure measurements of turbulence and finestructure measurements of velocity and density are analyzed to investigate the relationship between turbulence and the internal wave field in the Antarctic Circumpolar Current. These data reveal a systematic near-bottom overprediction of the turbulent kinetic energy dissipation rate by finescale parameterization methods in select locations. Sites of near-bottom overprediction are typically characterized by large near-bottom flow speeds and elevated topographic roughness. Further, lower-than-average shear-to-strain ratios indicative of a less near-inertial wave field, rotary spectra suggesting a predominance of upward internal wave energy propagation, and enhanced narrowband variance at vertical wavelengths on the order of 100 m are found at these locations. Finally, finescale overprediction is typically associated with elevated Froude numbers based on the near-bottom shear of the background flow, and a background flow with a systematic backing tendency. Agreement of microstructure- and finestructure-based estimates within the expected uncertainty of the parameterization away from these special sites, the reproducibility of the overprediction signal across various parameterization implementations, and an absence of indications of atypical instrument noise at sites of parameterization overprediction, all suggest that physics not encapsulated by the parameterization play a role in the fate of bottom-generated waves at these locations. Several plausible underpinning mechanisms based on the limited available evidence are discussed that offer guidance for future studies.
Abstract.
Brearley JA, Sheen KL, Naveira Garabato AC, Smeed DA, Waterman S (2013). Eddy-Induced Modulation of Turbulent Dissipation over Rough Topography in the Southern Ocean.
Journal of Physical Oceanography,
43(11), 2288-2308.
Abstract:
Eddy-Induced Modulation of Turbulent Dissipation over Rough Topography in the Southern Ocean
Abstract
. Mesoscale eddies are universal features of the ocean circulation, yet the processes by which their energy is dissipated remain poorly understood. One hypothesis argues that the interaction of strong geostrophic flows with rough bottom topography effects an energy transfer between eddies and internal waves, with the breaking of these waves causing locally elevated dissipation focused near the sea floor. This study uses hydrographic and velocity data from a 1-yr mooring cluster deployment in the Southern Ocean to test this hypothesis. The moorings were located over a small (~10 km) topographic obstacle to the east of Drake Passage in a region of high eddy kinetic energy, and one was equipped with an ADCP at 2800-m depth from which internal wave shear variance and dissipation rates were calculated. Examination of the ADCP time series revealed a predominance of upward-propagating internal wave energy and a significant correlation (r = 0.45) between shear variance levels and subinertial near-bottom current speeds. Periods of strong near-bottom flow coincided with increased convergence of eddy-induced interfacial form stress in the bottom 1500 m. Predictions of internal wave energy radiation were made from theory using measured near-bottom current speeds, and the mean value of wave radiation (5.3 mW m−2) was sufficient to support the dissipated power calculated from the ADCP. A significant temporal correlation was also observed between radiated and dissipated power. Given the ubiquity of strong eddy flows and rough topography in the Southern Ocean, the transfer from eddy to internal wave energy is likely to be an important term in closing the ocean energy budget.
Abstract.
Sheen KL, Brearley JA, Naveira Garabato AC, Smeed DA, Waterman S, Ledwell JR, Meredith MP, St. Laurent L, Thurnherr AM, Toole JM, et al (2013). Rates and mechanisms of turbulent dissipation and mixing in the Southern Ocean: Results from the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES).
Journal of Geophysical Research: Oceans,
118(6), 2774-2792.
Abstract:
Rates and mechanisms of turbulent dissipation and mixing in the Southern Ocean: Results from the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES)
The spatial distribution of turbulent dissipation rates and internal wavefield characteristics is analyzed across two contrasting regimes of the Antarctic Circumpolar Current (ACC), using microstructure and finestructure data collected as part of the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES). Mid-depth turbulent dissipation rates are found to increase from O(1×10-10Wkg -1) in the Southeast Pacific to O(1×10-9Wkg -1) in the Scotia Sea, typically reaching 3×10-9Wkg -1 within a kilometer of the seabed. Enhanced levels of turbulent mixing are associated with strong near-bottom flows, rough topography, and regions where the internal wavefield is found to have enhanced energy, a less-inertial frequency content and a dominance of upward propagating energy. These results strongly suggest that bottom-generated internal waves play a major role in determining the spatial distribution of turbulent dissipation in the ACC. The energy flux associated with the bottom internal wave generation process is calculated using wave radiation theory, and found to vary between 0.8 mW m -2 in the Southeast Pacific and 14 mW m-2 in the Scotia Sea. Typically, 10%-30% of this energy is found to dissipate within 1 km of the seabed. Comparison between turbulent dissipation rates inferred from finestructure parameterizations and microstructure-derived estimates suggests a significant departure from wave-wave interaction physics in the near-field of wave generation sites. Key Points Turbulence increases by an order of magnitude between SE Pacific & Scotia Sea Lee waves play a pivotal role in Southern Ocean diapycnal mixing and circulation 10-30 % of Southern Ocean predicted lee wave energy is dissipated locally ©2013. American Geophysical Union. All Rights Reserved.
Abstract.
Sheen KL, White NJ, Caulfield CP, Hobbs RW (2012). Seismic imaging of a large horizontal vortex at abyssal depths beneath the Sub-Antarctic Front. Nature Geoscience, 5(8), 542-546.
Sheen KL, White N, Caulfield CP, Hobbs RW (2011). Estimating Geostrophic Shear from Seismic Images of Oceanic Structure.
Journal of Atmospheric and Oceanic Technology,
28(9), 1149-1154.
Abstract:
Estimating Geostrophic Shear from Seismic Images of Oceanic Structure*
Abstract
. It is shown that geostrophic vertical shear estimates can be recovered from seismic (i.e. acoustic) images of thermohaline structure. In the Southern Ocean, the Antarctic Circumpolar Current forms a loop within the Falkland Trough before it flows northward into the Argentine Basin. Seismic profiles that cross this loop show the detailed structure of different water masses with a horizontal resolution of O(10 m). Coherent seismic reflections are tilted in response to current flow around the Falkland Trough. Average slopes were measured on length scales that are large enough to ensure that the geostrophic approximation is valid (i.e. with a Rossby number &lt;0.1). By combining shear estimates with satellite altimetric measurements and acoustic Doppler current profiles, geostrophic velocities can be calculated throughout the data volume. This technique for estimating geostrophic vertical shear from legacy seismic images yields useful information about the spatial and temporal variation of mesoscale circulation.
Abstract.
Sheen KL, White NJ, Hobbs RW (2009). Estimating mixing rates from seismic images of oceanic structure. Geophysical Research Letters, 36
Chapters
Gille ST, Sheen KL, Swart S, Thompson AF (2022). Chapter 12 Mixing in the Southern Ocean. In (Ed) Ocean Mixing, 301-327.
Sheen K, Gille S, Thompson A, Swart S (2021). Mixing in the Southern Ocean. In Garabato A, Meredith M (Eds.)
Ocean Mixing Drivers, Mechanisms and Impacts, Elsevier, 301-327.
Abstract:
Mixing in the Southern Ocean
Abstract.
Publications by year
In Press
Sheen KL, Smith DM, Dunstone NJ, Eade R, Rowell DP, Vellinga M (In Press). Skilful prediction of Sahel summer rainfall on inter-annual and multi-year timescales. Nature Communications
2023
Cox I, Brewin RJW, Dall'Olmo G, Sheen K, Sathyendranath S, Rasse R, Ulloa O (2023). Distinct habitat and biogeochemical properties of low‐oxygen‐adapted tropical oceanic phytoplankton.
Limnology and Oceanography,
68(9), 2022-2039.
Abstract:
Distinct habitat and biogeochemical properties of low‐oxygen‐adapted tropical oceanic phytoplankton
AbstractWe use data collected by Biogeochemical Argo (BGC‐Argo) float, over a 5‐year period (2016–2021), to study the dynamics of a unique low‐oxygen‐adapted phytoplanktonic community in the eastern tropical North Pacific. We isolate this community using a model that partitions vertical profiles of chlorophyll a (Chl a) and particulate backscattering into the contributions of three communities of phytoplankton: C1, the community in the mixed‐layer; C2, at the deep Chl a maximum; and C3, in low‐oxygen waters at the base of the euphotic zone. We find that C3 has a similar chl‐specific particulate backscattering to C2, both lower than C1. C2 and C3 contribute significantly to integrated stocks of Chl a, both at around 41%, and both around 30% of integrated particulate backscattering (after removing a background signal attributed to nonalgal particles). Found at depths of around 100 m, the peak biomass of C3 is lower than C2 (located at around 60 m), and yet, C3 makes similar contributions to integrated stocks, because it has a broader peak than C2. In relation to C1 and C2, C3 thrives in a lower temperature, higher density, lower light, lower oxygen, and higher saline habitat. This work illustrates how BGC‐Argo floats, in combination with simple conceptual models, can be used to observe the dynamics of unique communities of phytoplankton in extreme environments. The projected climate‐driven changes in oxygen minimum zones add urgency to understand the vulnerabilities of these communities both in terms of stocks and composition.
Abstract.
Ford DJ, Tilstone GH, Shutler JD, Kitidis V, Sheen KL, Dall’Olmo G, Orselli IBM (2023). Mesoscale Eddies Enhance the Air‐Sea CO<sub>2</sub> Sink in the South Atlantic Ocean.
Geophysical Research Letters,
50(9).
Abstract:
Mesoscale Eddies Enhance the Air‐Sea CO2 Sink in the South Atlantic Ocean
AbstractMesoscale eddies are abundant in the global oceans and known to affect oceanic and atmospheric conditions. Understanding their cumulative impact on the air‐sea carbon dioxide (CO2) flux may have significant implications for the ocean carbon sink. Observations and Lagrangian tracking were used to estimate the air‐sea CO2 flux of 67 long lived (>1 year) mesoscale eddies in the South Atlantic Ocean over a 16 year period. Both anticyclonic eddies originating from the Agulhas retroflection and cyclonic eddies originating from the Benguela upwelling act as net CO2 sinks over their lifetimes. Anticyclonic eddies displayed an exponential decrease in the net CO2 sink, whereas cyclonic eddies showed a linear increase. Combined, these eddies significantly enhanced the CO2 sink into the South Atlantic Ocean by 0.08 ± 0.04%. The studied eddies constitute a fraction of global eddies, and eddy activity is increasing; therefore, explicitly resolving eddies appears critical when assessing the ocean carbon sink.
Abstract.
2022
Gille ST, Sheen KL, Swart S, Thompson AF (2022). Chapter 12 Mixing in the Southern Ocean. In (Ed) Ocean Mixing, 301-327.
Gunn KL, Sheen KL, Tang Q (2022). Editorial: Acoustically Mapping the Ocean. Frontiers in Marine Science, 9
Meredith MP, Inall ME, Brearley JA, Ehmen T, Sheen K, Munday D, Cook A, Retallick K, Van Landeghem K, Gerrish L, et al (2022). Internal tsunamigenesis and ocean mixing driven by glacier calving in Antarctica.
Sci Adv,
8(47).
Abstract:
Internal tsunamigenesis and ocean mixing driven by glacier calving in Antarctica.
Ocean mixing around Antarctica exerts key influences on glacier dynamics and ice shelf retreats, sea ice, and marine productivity, thus affecting global sea level and climate. The conventional paradigm is that this is dominated by winds, tides, and buoyancy forcing. Direct observations from the Antarctic Peninsula demonstrate that glacier calving triggers internal tsunamis, the breaking of which drives vigorous mixing. Being widespread and frequent, these internal tsunamis are at least comparable to winds, and much more important than tides, in driving regional shelf mixing. They are likely relevant everywhere that marine-terminating glaciers calve, including Greenland and across the Arctic. Calving frequency may change with higher ocean temperatures, suggesting possible shifts to internal tsunamigenesis and mixing in a warming climate.
Abstract.
Author URL.
Ford DJ, Tilstone GH, Shutler JD, Kitidis V, Sheen KL, Dall'Olmo G, Orselli IBM (2022). Mesoscale eddies enhance the air-sea CO2 sink in the South Atlantic Ocean.
2021
Waterman S, Meyer A, Polzin KL, Naveira Garabato AC, Sheen KL (2021). Antarctic Circumpolar Current Impacts on Internal Wave Life Cycles.
Geophysical Research Letters,
48(8).
Abstract:
Antarctic Circumpolar Current Impacts on Internal Wave Life Cycles
Major gaps exist in our understanding of the pathways between internal wave generation and breaking in the Southern Ocean, with important implications for the distribution of internal wave-driven mixing, the sensitivity of ocean mixing rates and patterns to changes in the ocean environment, and the necessary ingredients of mixing parameterizations. Here we assess the dominant processes in internal wave evolution by characterizing wave and mesoscale flow scales based on full-depth in situ measurements in a Southern Ocean mixing hot spot and a ray tracing calculation. The exercise highlights the importance of Antarctic Circumpolar Current jets as a dominant influence on internal wave life cycles through advection, the modification of wave characteristics via wave-mean flow interactions, and the set-up of critical layers for both upward- and downward-propagating waves. Our findings suggest that it is important to represent mesoscale flow impacts in parameterizations of internal wave-driven mixing in the Southern Ocean.
Abstract.
Waterman S, Meyer A, Polzin K, Naveira Garabato AC, Sheen KL (2021). Antarctic Circumpolar Current impacts on internal wave life cycles.
Munoz-Ramirez CP, Beltran-Concha M, Perez-Araneda K, Sands CJ, Barnes DKA, Roman-Gonzalez A, de Lecea AM, Retallick K, van Landeghem K, Sheen K, et al (2021). Genetic variation in the small bivalve Nuculana inaequisculpta along a retreating glacier fjord, King George Island, Antarctica.
REVISTA DE BIOLOGIA MARINA Y OCEANOGRAFIA,
56(2), 151-156.
Author URL.
Sheen K, Fortnam M, Hailey P, Balfour N, Lea R (2021). Innovation history of the CMAM Surge approach Towards a shock-responsive health system in Kenya.
Sheen K, Gille S, Thompson A, Swart S (2021). Mixing in the Southern Ocean. In Garabato A, Meredith M (Eds.)
Ocean Mixing Drivers, Mechanisms and Impacts, Elsevier, 301-327.
Abstract:
Mixing in the Southern Ocean
Abstract.
Fortnam M, Atkins M, Brown K, Chaigneau T, Frouws A, Gwaro K, Huxham M, Kairo J, Kimeli A, Kirui B, et al (2021). Multiple impact pathways of the 2015-2016 El Niño in coastal Kenya.
Ambio,
50(1), 174-189.
Abstract:
Multiple impact pathways of the 2015-2016 El Niño in coastal Kenya.
The 2015-2016 El Niño had large impacts globally. The effects were not as great as anticipated in Kenya, however, leading some commentators to call it a 'non-event'. Our study uses a novel combination of participatory Climate Vulnerability and Capacity Analysis tools, and new and existing social and biophysical data, to analyse vulnerability to, and the multidimensional impacts of, the 2015-2016 El Niño episode in southern coastal Kenya. Using a social-ecological systems lens and a unique dataset, our study reveals impacts overlooked by conventional analysis. We show how El Niño stressors interact with and amplify existing vulnerabilities to differentially impact local ecosystems and people. The policy significance of this finding is that the development of specific national capacities to deal with El Niño events is insufficient; it will be necessary to also address local vulnerabilities to everyday and recurrent stressors and shocks to build resilience to the effects of El Niño and other extremes in climate and weather.
Abstract.
Author URL.
Xiao W, Sheen KL, Tang Q, Shutler J, Hobbs R, Ehmen T (2021). Temperature and Salinity Inverted for a Mediterranean Eddy Captured with Seismic Data, Using a Spatially Iterative Markov Chain Monte Carlo Approach. Frontiers in Marine Science, 8
Wilson DR, Godley BJ, Haggar GL, Santillo D, Sheen KL (2021). The influence of depositional environment on the abundance of microplastic pollution on beaches in the Bristol Channel, UK.
Mar Pollut Bull,
164Abstract:
The influence of depositional environment on the abundance of microplastic pollution on beaches in the Bristol Channel, UK.
Microplastic is a ubiquitous environmental contaminant, but large gaps still exist in our knowledge of its distribution. We conducted a detailed assessment of the extent and variability of microplastic pollution in the Bristol Channel, UK. Sand samples were collected between the 5th and 30th August 2017, with microplastic recovered from 15 of the 16 beaches sampled along a coastal extent of ~230 km. In total, 1446 particles of suspected microplastic were extracted using a cascade of sieves and visual identification. The most common microplastics recovered were fragments (74%) and industrial plastic pellets (13%). We used Fourier-Transform Infrared (FTIR) spectroscopy to analyse 25% of recovered particles, 96.5% of which were confirmed as plastic, with polyethylene (61%) and polypropylene (26%) the most common polymers. Our analysis of local beach environments indicates microplastic burdens were higher on lower energy beaches with finer sediments, highlighting the importance of depositional environment in determining microplastic abundance.
Abstract.
Author URL.
2020
Whalen CB, de Lavergne C, Naveira Garabato AC, Klymak JM, MacKinnon JA, Sheen KL (2020). Internal wave-driven mixing: governing processes and consequences for climate. Nature Reviews Earth & Environment, 1(11), 606-621.
Bascur M, Muñoz-Ramírez C, Román-González A, Sheen K, Barnes DKA, Sands CJ, Brante A, Urzúa Á (2020). The influence of glacial melt and retreat on the nutritional condition of the bivalve Nuculana inaequisculpta (Protobranchia: Nuculanidae) in the West Antarctic Peninsula. PLOS ONE, 15(5), e0233513-e0233513.
2019
Abrahamsen EP, Meijers AJS, Polzin KL, Naveira Garabato AC, King BA, Firing YL, Sallée J-B, Sheen KL, Gordon AL, Huber BA, et al (2019). Stabilization of dense Antarctic water supply to the Atlantic Ocean overturning circulation. Nature Climate Change, 9(10), 742-746.
2018
Dunstone N, Smith D, Scaife A, Hermanson L, Fereday D, O'Reilly C, Stirling A, Eade R, Gordon M, MacLachlan C, et al (2018). Skilful Seasonal Predictions of Summer European Rainfall.
Geophysical Research Letters,
45(7), 3246-3254.
Abstract:
Skilful Seasonal Predictions of Summer European Rainfall
Year-to-year variability in Northern European summer rainfall has profound societal and economic impacts; however, current seasonal forecast systems show no significant forecast skill. Here we show that skillful predictions are possible (r ~0.5, p 80 members) are required for skillful predictions. This work is promising for the development of European summer rainfall climate services.
Abstract.
2016
Clement L, Frajka-Williams E, Sheen KL, Brearley JA, Garabato ACN (2016). Generation of Internal Waves by Eddies Impinging on the Western Boundary of the North Atlantic.
JOURNAL OF PHYSICAL OCEANOGRAPHY,
46(4), 1067-1079.
Author URL.
Smith DM, Booth BBB, Dunstone NJ, Eade R, Hermanson L, Jones GS, Scaife AA, Sheen KL, Thompson V (2016). Role of volcanic and anthropogenic aerosols in the recent global surface warming slowdown. Nature Climate Change, 6(10), 936-940.
2015
Trossman DS, Waterman S, Polzin KL, Arbic BK, Garner ST, Naveira-Garabato AC, Sheen KL (2015). Internal lee wave closures: Parameter sensitivity and comparison to observations.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS,
120(12), 7997-8019.
Author URL.
Sheen KL, Brearley JA, Naveira Garabato AC, Smeed DA, Laurent LS, Meredith MP, Thurnherr AM, Waterman SN (2015). Modification of turbulent dissipation rates by a deep Southern Ocean eddy.
Geophysical Research Letters,
42(9), 3450-3457.
Abstract:
Modification of turbulent dissipation rates by a deep Southern Ocean eddy
AbstractThe impact of a mesoscale eddy on the magnitude and spatial distribution of diapycnal ocean mixing is investigated using a set of hydrographic and microstructure measurements collected in the Southern Ocean. These data sampled a baroclinic, middepth eddy formed during the disintegration of a deep boundary current. Turbulent dissipation is suppressed within the eddy but is elevated by up to an order of magnitude along the upper and lower eddy boundaries. A ray tracing approximation is employed as a heuristic device to elucidate how the internal wave field evolves in the ambient velocity and stratification conditions accompanying the eddy. These calculations are consistent with the observations, suggesting reflection of internal wave energy from the eddy center and enhanced breaking through critical layer processes along the eddy boundaries. These results have important implications for understanding where and how internal wave energy is dissipated in the presence of energetic deep geostrophic flows.
Abstract.
Sarkar S, Sheen KL, Klaeschen D, Brearley JA, Minshull TA, Berndt C, Hobbs RW, Garabato ACN (2015). Seismic reflection imaging of mixing processes in Fram Strait.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS,
120(10), 6884-6896.
Author URL.
Sévellec F, Naveira Garabato AC, Brearley JA, Sheen KL (2015). Vertical Flow in the Southern Ocean Estimated from Individual Moorings.
Journal of Physical Oceanography,
45(9), 2209-2220.
Abstract:
Vertical Flow in the Southern Ocean Estimated from Individual Moorings
AbstractThis study demonstrates that oceanic vertical velocities can be estimated from individual mooring measurements, even for nonstationary flow. This result is obtained under three assumptions: (i) weak diffusion (Péclet number ≫ 1), (ii) weak friction (Reynolds number ≫ 1), and (iii) small inertial terms (Rossby number ≪ 1). The theoretical framework is applied to a set of four moorings located in the Southern Ocean. For this site, the diagnosed vertical velocities are highly variable in time, their standard deviation being one to two orders of magnitude greater than their mean. The time-averaged vertical velocities are demonstrated to be largely induced by geostrophic flow and can be estimated from the time-averaged density and horizontal velocities. This suggests that local time-mean vertical velocities are primarily forced by the time-mean ocean dynamics, rather than by, for example, transient eddies or internal waves. It is also shown that, in the context of these four moorings, the time-mean vertical flow is consistent with stratified Taylor column dynamics in the presence of a topographic obstacle.
Abstract.
2014
Brearley JA, Sheen KL, Naveira Garabato AC, Smeed DA, Speer KG, Thurnherr AM, Meredith MP, Waterman S (2014). Deep boundary current disintegration in Drake Passage. Geophysical Research Letters, 41(1), 121-127.
Sheen KL, Garabato ACN, Brearley JA, Meredith MP, Polzin KL, Smeed DA, Forryan A, King BA, Sallée JB, St. Laurent L, et al (2014). Eddy-induced variability in Southern Ocean abyssal mixing on climatic timescales.
Nature Geoscience,
7(8), 577-582.
Abstract:
Eddy-induced variability in Southern Ocean abyssal mixing on climatic timescales
The Southern Ocean plays a pivotal role in the global ocean circulation and climate. There, the deep water masses of the world ocean upwell to the surface and subsequently sink to intermediate and abyssal depths, forming two overturning cells that exchange substantial quantities of heat and carbon with the atmosphere. The sensitivity of the upper cell to climatic changes in forcing is relatively well established. However, little is known about how the lower cell responds, and in particular whether small-scale mixing in the abyssal Southern Ocean, an important controlling process of the lower cell, is influenced by atmospheric forcing. Here, we present observational evidence that relates changes in abyssal mixing to oceanic eddy variability on timescales of months to decades. Observational estimates of mixing rates, obtained along a repeat hydrographic transect across Drake Passage, are shown to be dependent on local oceanic eddy energy, derived from moored current meter and altimetric measurements. As the intensity of the regional eddy field is regulated by the Southern Hemisphere westerly winds, our findings suggest that Southern Ocean abyssal mixing and overturning are sensitive to climatic perturbations in wind forcing. © 2014 Macmillan Publishers Limited.
Abstract.
Waterman S, Polzin KL, Naveira Garabato AC, Sheen KL, Forryan A (2014). Suppression of Internal Wave Breaking in the Antarctic Circumpolar Current near Topography.
Journal of Physical Oceanography,
44(5), 1466-1492.
Abstract:
Suppression of Internal Wave Breaking in the Antarctic Circumpolar Current near Topography
Abstract
. Simultaneous full-depth microstructure measurements of turbulence and finestructure measurements of velocity and density are analyzed to investigate the relationship between turbulence and the internal wave field in the Antarctic Circumpolar Current. These data reveal a systematic near-bottom overprediction of the turbulent kinetic energy dissipation rate by finescale parameterization methods in select locations. Sites of near-bottom overprediction are typically characterized by large near-bottom flow speeds and elevated topographic roughness. Further, lower-than-average shear-to-strain ratios indicative of a less near-inertial wave field, rotary spectra suggesting a predominance of upward internal wave energy propagation, and enhanced narrowband variance at vertical wavelengths on the order of 100 m are found at these locations. Finally, finescale overprediction is typically associated with elevated Froude numbers based on the near-bottom shear of the background flow, and a background flow with a systematic backing tendency. Agreement of microstructure- and finestructure-based estimates within the expected uncertainty of the parameterization away from these special sites, the reproducibility of the overprediction signal across various parameterization implementations, and an absence of indications of atypical instrument noise at sites of parameterization overprediction, all suggest that physics not encapsulated by the parameterization play a role in the fate of bottom-generated waves at these locations. Several plausible underpinning mechanisms based on the limited available evidence are discussed that offer guidance for future studies.
Abstract.
2013
Brearley JA, Sheen KL, Naveira Garabato AC, Smeed DA, Waterman S (2013). Eddy-Induced Modulation of Turbulent Dissipation over Rough Topography in the Southern Ocean.
Journal of Physical Oceanography,
43(11), 2288-2308.
Abstract:
Eddy-Induced Modulation of Turbulent Dissipation over Rough Topography in the Southern Ocean
Abstract
. Mesoscale eddies are universal features of the ocean circulation, yet the processes by which their energy is dissipated remain poorly understood. One hypothesis argues that the interaction of strong geostrophic flows with rough bottom topography effects an energy transfer between eddies and internal waves, with the breaking of these waves causing locally elevated dissipation focused near the sea floor. This study uses hydrographic and velocity data from a 1-yr mooring cluster deployment in the Southern Ocean to test this hypothesis. The moorings were located over a small (~10 km) topographic obstacle to the east of Drake Passage in a region of high eddy kinetic energy, and one was equipped with an ADCP at 2800-m depth from which internal wave shear variance and dissipation rates were calculated. Examination of the ADCP time series revealed a predominance of upward-propagating internal wave energy and a significant correlation (r = 0.45) between shear variance levels and subinertial near-bottom current speeds. Periods of strong near-bottom flow coincided with increased convergence of eddy-induced interfacial form stress in the bottom 1500 m. Predictions of internal wave energy radiation were made from theory using measured near-bottom current speeds, and the mean value of wave radiation (5.3 mW m−2) was sufficient to support the dissipated power calculated from the ADCP. A significant temporal correlation was also observed between radiated and dissipated power. Given the ubiquity of strong eddy flows and rough topography in the Southern Ocean, the transfer from eddy to internal wave energy is likely to be an important term in closing the ocean energy budget.
Abstract.
Sheen KL, Brearley JA, Naveira Garabato AC, Smeed DA, Waterman S, Ledwell JR, Meredith MP, St. Laurent L, Thurnherr AM, Toole JM, et al (2013). Rates and mechanisms of turbulent dissipation and mixing in the Southern Ocean: Results from the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES).
Journal of Geophysical Research: Oceans,
118(6), 2774-2792.
Abstract:
Rates and mechanisms of turbulent dissipation and mixing in the Southern Ocean: Results from the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES)
The spatial distribution of turbulent dissipation rates and internal wavefield characteristics is analyzed across two contrasting regimes of the Antarctic Circumpolar Current (ACC), using microstructure and finestructure data collected as part of the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES). Mid-depth turbulent dissipation rates are found to increase from O(1×10-10Wkg -1) in the Southeast Pacific to O(1×10-9Wkg -1) in the Scotia Sea, typically reaching 3×10-9Wkg -1 within a kilometer of the seabed. Enhanced levels of turbulent mixing are associated with strong near-bottom flows, rough topography, and regions where the internal wavefield is found to have enhanced energy, a less-inertial frequency content and a dominance of upward propagating energy. These results strongly suggest that bottom-generated internal waves play a major role in determining the spatial distribution of turbulent dissipation in the ACC. The energy flux associated with the bottom internal wave generation process is calculated using wave radiation theory, and found to vary between 0.8 mW m -2 in the Southeast Pacific and 14 mW m-2 in the Scotia Sea. Typically, 10%-30% of this energy is found to dissipate within 1 km of the seabed. Comparison between turbulent dissipation rates inferred from finestructure parameterizations and microstructure-derived estimates suggests a significant departure from wave-wave interaction physics in the near-field of wave generation sites. Key Points Turbulence increases by an order of magnitude between SE Pacific & Scotia Sea Lee waves play a pivotal role in Southern Ocean diapycnal mixing and circulation 10-30 % of Southern Ocean predicted lee wave energy is dissipated locally ©2013. American Geophysical Union. All Rights Reserved.
Abstract.
2012
Sheen KL, White NJ, Caulfield CP, Hobbs RW (2012). Seismic imaging of a large horizontal vortex at abyssal depths beneath the Sub-Antarctic Front. Nature Geoscience, 5(8), 542-546.
2011
Sheen KL, White N, Caulfield CP, Hobbs RW (2011). Estimating Geostrophic Shear from Seismic Images of Oceanic Structure.
Journal of Atmospheric and Oceanic Technology,
28(9), 1149-1154.
Abstract:
Estimating Geostrophic Shear from Seismic Images of Oceanic Structure*
Abstract
. It is shown that geostrophic vertical shear estimates can be recovered from seismic (i.e. acoustic) images of thermohaline structure. In the Southern Ocean, the Antarctic Circumpolar Current forms a loop within the Falkland Trough before it flows northward into the Argentine Basin. Seismic profiles that cross this loop show the detailed structure of different water masses with a horizontal resolution of O(10 m). Coherent seismic reflections are tilted in response to current flow around the Falkland Trough. Average slopes were measured on length scales that are large enough to ensure that the geostrophic approximation is valid (i.e. with a Rossby number &lt;0.1). By combining shear estimates with satellite altimetric measurements and acoustic Doppler current profiles, geostrophic velocities can be calculated throughout the data volume. This technique for estimating geostrophic vertical shear from legacy seismic images yields useful information about the spatial and temporal variation of mesoscale circulation.
Abstract.
2009
Sheen KL, White NJ, Hobbs RW (2009). Estimating mixing rates from seismic images of oceanic structure. Geophysical Research Letters, 36
