Physical oceanography

  • Article
    | Open Access

    The motion of the ocean transports microorganisms, pollutants, and other particles, but these are challenging to track. Here the authors present a Lagrangian form of Betweenness Centrality which identifies bottlenecks in dynamical systems and fluid flows as well as an interpretation of diversity hotspots.

    • Enrico Ser-Giacomi
    • , Alberto Baudena
    •  & Emilio Hernández-García
  • Article
    | Open Access

    Marine heat waves and cold spells threaten ocean ecosystems and are thought to be increasing with climate change. Here the author shows that MHW/MCS in the Tasman Sea co-occur with corresponding events in the Atlantic, Indian, and Pacific Oceans, and these southern hemisphere events are driven by stalling of a global wavenumber-4 atmospheric wave.

    • Stephen M. Chiswell
  • Article
    | Open Access

    The deep North Pacific is the end of the road for global ocean circulation, but the circulation patterns and ventilation are poorly understood. Here the authors show that diffusive transports both along and across density layers play a leading role in returning 1,400 year old water to the surface.

    • Mark Holzer
    • , Tim DeVries
    •  & Casimir de Lavergne
  • Article
    | Open Access

    Estimating velocities in gas liquid flows is of importance in many engineering applications. Hohermuth et al. show that previous bubble velocities obtained from intrusive probes have been underestimated and provide a correction scheme for more accurate velocity measurements.

    • B. Hohermuth
    • , M. Kramer
    •  & D. Valero
  • Article
    | Open Access

    How sea-level in the western Mediterranean reacts to climate changes is not well known. Here, the authors present a regional reconstruction and show that temperatures influenced sea-level change rates during the Holocene, while recent sea-level rise is happening faster than during any other period of the last 4000 years.

    • Matteo Vacchi
    • , Kristen M. Joyse
    •  & Alessio Rovere
  • Article
    | Open Access

    Reprocessed data from satellite altimetry show that the mean significant wave height decreases globally by 22% on average from 30 km to 3 km from the coast. By combining these data with wave period from reanalysis, we estimate a mean reduction of 38% concerning the mean wave energy flux.

    • Marcello Passaro
    • , Mark A. Hemer
    •  & Florian Seitz
  • Article
    | Open Access

    As sea levels rise, coasts are being increasingly  threatened by overtopping caused by the combination of sea level rise, storm surge and wave runup. Here the authors find that global coastal overtopping has increased by over 50% in the last two decades, and under a RCP 8.5 scenario this could increase up to 50 times by 2100 compared to today.

    • Rafael Almar
    • , Roshanka Ranasinghe
    •  & Elodie Kestenare
  • Article
    | Open Access

    New data from five hot-water drilled boreholes show how atmospheric anomalies affect the circulation beneath Filchner-Ronne Ice Shelf on multi-year time scales. The apparent link of the dense water formation to remote teleconnections is an important step for better predicting contributions to future sea level rise from this sector of Antarctica.

    • Tore Hattermann
    • , Keith W. Nicholls
    •  & Torsten Kanzow
  • Article
    | Open Access

    The Arctic Ocean cooling machine, currently the Barents Sea, plays a crucial role in both regulating the climate and determining the deep ocean circulation. Here the authors show that the efficiency of the cooling machine is poleward enhanced in a warming climate, which pushes Arctic Atlantification poleward.

    • Qi Shu
    • , Qiang Wang
    •  & Fangli Qiao
  • Article
    | Open Access

    Warming ocean water plays a significant role in accelerating Arctic sea ice melt. Here the authors present detailed observations of warm water of Pacific origin entering and diving beneath the Arctic ocean surface, and explore the dynamical processes governing its evolution.

    • Jennifer A. MacKinnon
    • , Harper L. Simmons
    •  & Kevin R. Wood
  • Article
    | Open Access

    New simulations find that one of Antarctica’s largest ice shelves, the Filchner–Ronne, may be less vulnerable to climate change than previously thought. Melting of the ice shelf initially decreases for many decades, and only increases when global warming exceeds approximately 7 °C.

    • Kaitlin A. Naughten
    • , Jan De Rydt
    •  & Jeff K. Ridley
  • Article
    | Open Access

    Atmospheric rivers are responsible for much of the poleward water vapour transport in the mid-latitudes and can cause extreme precipitation after landfall. Here, the authors show that ocean fronts and eddies can influence atmospheric rivers and increase the associated precipitation along the North American west coast.

    • Xue Liu
    • , Xiaohui Ma
    •  & Christina M. Patricola
  • Article
    | Open Access

    The Beaufort Gyre in the western Arctic Ocean has accumulated a large amount of freshwater. Here, the authors show that a historical release in the 1980s resulted in a strong freshening of the western Labrador Sea, suggesting that a future release of the current freshwater volume could even be more impactful.

    • Jiaxu Zhang
    • , Wilbert Weijer
    •  & Milena Veneziani
  • Article
    | Open Access

    The Getz region of West Antarctica is losing ice at an increasing rate; however, the forcing mechanisms remain unclear. Here we show for the first time that since 1994, widespread speedup has occurred on the majority of glaciers in the Getz drainage basin, with some glaciers speeding up by over 44 %.

    • Heather L. Selley
    • , Anna E. Hogg
    •  & Tae-Wan Kim
  • Article
    | Open Access

    Evaluating sea-level projections used by the IPCC is challenging due to the short overlap with measurements. Here, the authors show that observed global and regional sea-level trends confirm projections and that the acceleration of sea-level rise is between the one expected from the scenarios RCP4.5 and RCP8.5.

    • Jinping Wang
    • , John A. Church
    •  & Xianyao Chen
  • Article
    | Open Access

    Eddy heat fluxes crucially affect large-scale oceanic currents but are challenging to monitor on a global scale. Here the authors develop a Deep Learning model to predict the eddy heat fluxes from sea surface height data only, bypassing the need for simultaneous observations of the deep ocean.

    • Tom M. George
    • , Georgy E. Manucharyan
    •  & Andrew F. Thompson
  • Article
    | Open Access

    The Southern Ocean takes up the most heat and carbon, yet because of its remote and harsh location, it remains relatively sparsely measured. Here the authors use a 25 year temperature series which shows a clear, long term trend in subsurface warming that emerges from interannual variability.

    • Matthis Auger
    • , Rosemary Morrow
    •  & Rebecca Cowley
  • Article
    | Open Access

    How and why the ‘Snowball Earth’ occurred during the Cryogenian period is debated. Here, the authors show that the cryogenian ocean hosted diminished tidal amplitudes and associated energy dissipation rates, reaching 10-50% of today’s rates thus perhaps contributing to prolonged glaciations.

    • J. A. Mattias Green
    • , Hannah S. Davies
    •  & Christopher Scotese
  • Article
    | Open Access

    Iceberg melting releases large volumes of freshwater in fjords, yet the impact on oceanic heat delivery to tidewater glaciers is unknown. Here the authors show that iceberg melting invigorates fjord circulation in a large, iceberg-congested fjord, thereby increasing oceanic heat delivery to its tidewater glaciers.

    • B. J. Davison
    • , T. R. Cowton
    •  & A. J. Sole
  • Article
    | Open Access

    Dense water from the Nordic Seas sustains the Atlantic Meridional Overturning Circulation, yet the upstream pathways are not fully known. Here, the authors provide evidence of a deep current between Iceland and the Faroe Islands, which supplies 50% of the transport through the Faroe Bank Channel overflow.

    • Stefanie Semper
    • , Robert S. Pickart
    •  & Bogi Hansen
  • Article
    | Open Access

    Overflow water is an important part of the Atlantic Meridional Overturning Circulation, yet how it reaches the Greenland-Scotland Ridge is not fully known. Here, the authors show that the interior of the Greenland Sea gyre is the primary wintertime source of the densest portion of both Denmark Strait and Faroe Bank Channel overflows.

    • Jie Huang
    • , Robert S. Pickart
    •  & Fanghua Xu
  • Article
    | Open Access

    How the El Niño Southern Oscillation depends on the background conditions is not well known. Here, the authors present individual foraminifera distributions which show that central Pacific variability is related to the warmth and depth of the thermocline across varying climate background conditions over the past ~285,000 years.

    • Gerald T. Rustic
    • , Pratigya J. Polissar
    •  & Sarah M. White
  • Article
    | Open Access

    This study investigates the effect of changing sea level on deep sea gas emissions in the Arctic. The results show that small decreases in sea-level favors gas release. This implies that sea-level rise may partially counterbalance the effect of warming oceans on gas emissions overall.

    • Nabil Sultan
    • , Andreia Plaza-Faverola
    •  & Jochen Knies
  • Article
    | Open Access

    Exposure to extreme events is a major concern in coastal regions where human populations and stressed ecosystems are at risk to such phenomena. Here the authors show a marine heatwave on the continental shelf resulted from a novel set of compounding effects due to a tropical storm followed by an atmospheric heatwave.

    • B. Dzwonkowski
    • , J. Coogan
    •  & T. Lee
  • Article
    | Open Access

    Trough mouth fans are created via repeated glacigenic sediment transport from ice sheets. Here the authors use 3D seismic reflection data to present a formation model for the North Sea Fan and find that exceptionally large volumes of meltwater may mean that freshwater supply is underestimated during glacial cycles.

    • Benjamin Bellwald
    • , Sverre Planke
    •  & Reidun Myklebust
  • Article
    | Open Access

    The asymmetry between El Niño and La Niña episodes in the tropical Pacific is often not well represented in models. Here, the authors show that this asymmetry is related to subsurface nonlinear dynamical heating and that a realistic representation of this process can potentially improve tropical climate projections.

    • Michiya Hayashi
    • , Fei-Fei Jin
    •  & Malte F. Stuecker
  • Article
    | Open Access

    East Antarctic ice shelves typically have cold ice cavities with low basal melt rates. Here the authors direct observational evidence of high basal melt rates beneath Shirase Glacier Tongue in East Antarctica, driven by inflowing warm water guided by a deep continuous trough extending to the continental slope.

    • Daisuke Hirano
    • , Takeshi Tamura
    •  & Shigeru Aoki
  • Article
    | Open Access

    Some palaeotemperature proxies suffer from inaccuracies related to kinetic fractionations occurring during carbonate mineral growth. Here, the authors show that dual clumped isotope thermometry can identify the origin of these kinetic biases and allows for the reconstruction of accurate environmental temperatures.

    • David Bajnai
    • , Weifu Guo
    •  & Jens Fiebig
  • Article
    | Open Access

    Predicted sea-level rise is widely anticipated to lead to increased coastal erosion, however, assessing how rocky coasts will respond to changes in marine conditions is difficult to constrain. Here, the authors find that a North Yorkshire rocky cliff has been eroding at a similar rate over the last 7 kyr, and they do not observe an increase in erosion rates in response to modern sea level rise.

    • Zuzanna M. Swirad
    • , Nick J. Rosser
    •  & John Barlow
  • Article
    | Open Access

    Every year, hundreds of people die at sea because of vessel accidents, and a key challenge in reducing these fatalities is to make Search and Rescue (SAR) planning more efficient. Here, the authors uncover hidden flow features that attract floating objects, providing specific information for optimal SAR planning.

    • Mattia Serra
    • , Pratik Sathe
    •  & George Haller
  • Article
    | Open Access

    The non-linear interaction between tide and non-tidal residual impacts current and future extreme water levels. Here, based on 620 gauge records, the authors find a large non-linear interaction in the US East Coast, North Sea and parts of southern Japan, that results in a reduction of extreme sea levels.

    • Arne Arns
    • , Thomas Wahl
    •  & Jürgen Jensen
  • Article
    | Open Access

    Global ocean circulation overturns and starts anew in the North Atlantic, propagating climate signals to the rest of the oceans. Using drifter data, Zou and colleagues re-map the spreading pattern for one of the deep water masses and show the impact of mesoscale processes on that pattern.

    • Sijia Zou
    • , Amy Bower
    •  & Xiaobiao Xu
  • Article
    | Open Access

    The North Atlantic current has been suspected to trigger intrusions of temperate marine species in the Arctic. Here, Oziel and colleagues reveal the link between the poleward intrusion of the temperate coccolithophore Emiliania huxleyi and the North Atlantic current, showing evidence for bio-advection as an important mechanism.

    • L. Oziel
    • , A. Baudena
    •  & M. Babin
  • Article
    | Open Access

    The Southern Ocean is an important sink of carbon via the biological pump. Here authors run high-resolution physical/biogeochemical simulations of an open-Southern Ocean ecosystem forced with a realistic seasonal cycle and confirm that (sub)mesoscale iron transport across the mixing-layer base sustains primary productivity.

    • Takaya Uchida
    • , Dhruv Balwada
    •  & Marina Lévy
  • Article
    | Open Access

    The freshwater content of the Beaufort Gyre in the Western Arctic Ocean has increased in response to almost two decades of persistent anti-cyclonic winds. Here, the authors found that dramatic loss of sea ice and acceleration of surface currents after 2007 led to a net annual wind energy input to the Beaufort Gyre, and anticipate that continued sea ice decline will lead to an increasingly energetic Beaufort Gyre.

    • Thomas W. K. Armitage
    • , Georgy E. Manucharyan
    •  & Andrew F. Thompson
  • Article
    | Open Access

    Ross Sea Bottom Water, a major source of Antarctic Bottom Water, has experienced significant freshening in recent decades. Here the authors use 23 years of summer measurements to document temporal variability in the salinity of the Ross Sea High Salinity Shelf Water (HSSW) and found that HSSW salinity decreased between 1995 and 2014 and rebounded sharply after 2014.

    • Pasquale Castagno
    • , Vincenzo Capozzi
    •  & Giorgio Budillon
  • Article
    | Open Access

    The California Current System is characterized by wind-driven upwelling and by rich mesoscale eddy activity, resulting in a highly productive ecosystem. Here the authors show that offshore cyclonic eddies which were generated near the coast contain higher carbon concentrations in their interior than eddies of the same amplitude generated locally offshore.

    • Caitlin M. Amos
    • , Renato M. Castelao
    •  & Patricia M. Medeiros
  • Article
    | Open Access

    The marginal interaction zones of oceans are understudied. Here, the authors analyse seismic observations of temporal changes at the interface between thermocline layers in the Panama Basin, that reveal a critical mixing state in which turbulent diffusion is gradually replaced by double-diffusion as the dominant mixing process.

    • Qunshu Tang
    • , Vincent C. H. Tong
    •  & Miguel Ángel Morales Maqueda
  • Article
    | Open Access

    The nature of erosion featured at the outlet of submarine channels is still a topic of debate. Here the authors present, based on scaled experiments, a novel flow mechanism for turbidity currents at the end of submarine channels and for the first time describe their erosional character.

    • F. Pohl
    • , J. T. Eggenhuisen
    •  & M. J. B. Cartigny
  • Article
    | Open Access

    During the Miocene, the Central American seaway was not closed, allowing low-salinity Pacific water to potentially weaken the Atlantic circulation. A new, continuous Nd isotope record shows that there was no direct intermediate water mass export from the Caribbean to the Florida Strait and thus, the Atlantic circulation could strengthen.

    • Valeriia Kirillova
    • , Anne H. Osborne
    •  & Martin Frank
  • Article
    | Open Access

    Tropical cyclone-induced coastal flooding will increase under climate change. Here the authors estimate the effects of sea level rise and tropical cyclone climatology change on late–21st–century flood hazards along the US Atlantic and Gulf Coasts and find that the effect of tropical cyclone change could surpass the effect of sea level rise at some areas in the Gulf of Mexico.

    • Reza Marsooli
    • , Ning Lin
    •  & Kairui Feng