Filtering by Subject: Oceanography

High-resolution observations of the North Pacific transition layer from a Lagrangian float

Alexis Kaminski, Eric A. D'Asaro, Andrey Y. Shcherbina, Ramsey R. Harcourt

Published: 2021-02-11
Subjects: Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

A crucial region of the ocean surface boundary layer (OSBL) is the strongly-sheared and -stratified transition layer (TL) separating the mixed layer from the upper pycnocline, where a diverse range of waves and instabilities are possible. Previous work suggests that these different waves and instabilities will lead to different OSBL behaviours. Therefore, understanding which physical processes [...]

Modeling and SAR Imaging of the Sea Surface: a Review of the State-of-the-Art with Simulations

Igor Rizaev, Oktay Karakus, John Hogan, Alin Achim

Published: 2021-02-10
Subjects: Oceanography

Among other remote sensing technologies, synthetic aperture radar (SAR) has become firmly established in the practice of oceanographic research. Despite solid experience in this field, comprehensive knowledge and interpretation of ocean/sea and vessel wave signatures on radar images are still very challenging. This is not only due to the complex mechanisms involved in the SAR imaging of moving [...]

Dynamical attribution of North Atlantic interdecadal predictability to oceanic and atmospheric turbulence under realistic and optimal stochastic forcing

Dafydd Stephenson, Florian Sévellec

Published: 2021-02-01
Subjects: Climate, Environmental Sciences, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

Unpredictable variations in the ocean originate from both external atmospheric forcing and chaotic processes internal to the ocean itself, and are a crucial sink of predictability on interdecadal timescales. In a global ocean model, we present i.) an optimisation framework to compute the most efficient noise patterns to generate uncertainty and ii.) a uniquely inexpensive, dynamical method for [...]

The active and passive roles of the ocean in generating basin-scale heat content variability

Dafydd Stephenson, Florian Sévellec

Published: 2021-01-28
Subjects: Climate, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

The role of ocean circulation in transforming surface forcing into interannual-to-multidecadal oceanic variability is an area of ongoing debate. Here, a novel method, establishing exact causal links, is used to quantitatively determine the role of ocean active and passive processes in transforming stochastic surface forcing into heat content variability. To this end, we use a global ocean model [...]

Vertical fluxes conditioned on vorticity and strain reveal submesoscale ventilation

Dhruv Balwada, Qiyu Xiao, Shafer Smith, Ryan Abernathey, Alison Gray

Published: 2021-01-24
Subjects: Oceanography, Oceanography and Atmospheric Sciences and Meteorology

It has been hypothesized that submesoscale flows play an important role in the vertical transport of climatically important tracers, due to their strong associated vertical velocities. However, the multi-scale, non-linear and Lagrangian nature of transport makes it challenging to attribute proportions of the tracer fluxes to certain processes, scales, regions or flow features. Here we show that [...]

The Rayleigh-Haring-Tayfun distribution of wave heights in deep water

Saulo Mendes, Alberto Scotti

Published: 2021-01-17
Subjects: Engineering, Fluid Dynamics, Hydraulic Engineering, Oceanography, Statistical Models

Regarding wave statistics, nearly every known exceeding probability distribution applied to rogue waves has shown disagreement with its peers. More often than not, models and experiments have shown a fair agreement with the Rayleigh distribution whereas others show that the latter underpredicts extreme heights by almost one order of magnitude. Virtually all previous results seem to be [...]

Near-inertial dissipation due to stratified flow over abyssal topography

Varvara E Zemskova, Nicolas Grisouard

Published: 2021-01-12
Subjects: Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

Linear theory for steady stratified flow over topography sets the range for topographic wavenumbers over which freely propagating internal waves are generated, and the radiation and breaking of these waves contribute to energy dissipation away from the ocean bottom. However, previous numerical work demonstrated that dissipation rates can be enhanced by flow over large scale topographies with [...]

Enhanced hydrological cycle increases ocean heat uptake and moderates transient climate sensitivity

Maofeng Liu, Gabriel Vecchi, Brian Soden, Wenchang Yang, Bosong Zhang

Published: 2020-11-25
Subjects: Climate, Oceanography, Oceanography and Atmospheric Sciences and Meteorology

The large-scale moistening of the atmosphere in response to the greenhouse gas increases tends to amplify the existing patterns of precipitation minus evaporation (P-E) which, in turn, amplifies the spatial contrast in sea surface salinity (SSS). We propose that subtropical surface salinification due to the intensified hydrological cycle provides a buoyancy sink that increases the rate of ocean [...]

Ventilation of the abyss in the Atlantic sector of the Southern Ocean

Camille Akhoudas, Jean-Baptiste Sallée, Alexander Haumann, Michael Meredith, Alberto Naveira-Garabato, Gilles Reverdin, Loïc Jullion, Giovanni Aloisi, Marion Benetti, Melanie Leng, Carol Arrowsmith

Published: 2020-11-10
Subjects: Oceanography

The Atlantic sector of the Southern Ocean is the world’s main production site of Antarctic Bottom Water, a water-mass that is ventilated at the ocean surface before sinking and entraining older water-masses – ultimately replenishing the abyssal global ocean. In recent decades, numerous attempts at estimating the rates of ventilation and overturning of Antarctic Bottom Water in this region have [...]

Utilizing Distributed Acoustic Sensing and Ocean Bottom Fiber Optic Cables for Submarine Structural Characterization

Feng Cheng, Jonathan Ajo-Franklin, Benxin Chi, Nathaniel J. Lindsey, Craig T. Dawe

Published: 2020-11-09
Subjects: Geophysics and Seismology, Oceanography

The sparsity of permanent seismic instrumentation in marine environments often limits the availability of subsea information on geohazards, including active fault systems, in both time and space. One sensing resource that may provide observational access to the seafloor environment are existing networks of ocean bottom fiber optic cables; these cables, coupled to modern distributed acoustic [...]

A Storm Hazard Matrix combining coastal flooding and beach erosion

Christopher Kenji Leaman, Mitchell D Harley, Kristen D Splinter, Mandi C Thran, Michael A Kinsela, Ian L Turner

Published: 2020-10-24
Subjects: Oceanography, Other Civil and Environmental Engineering

Coastal storms cause widespread damage to property, infrastructure, economic activity and the environment. Along open sandy coastlines, two of the primary coastal storm hazards are coastal flooding by elevated ocean water levels and beach erosion as the result of storm wave action. At continental margins characterized by a shallow, wide continental shelf, coastal storms are more commonly [...]

1600 year-long sedimentary record of tsunamis and hurricanes in the Lesser Antilles (Scrub Island, Anguilla)

Maude BIGUENET, Pierre Sabatier, Eric Chaumillon, Catherine Chagué, Fabien Arnaud, Frans Jorissen, Thibault Coulombier, Emeline Geba, Louise Cordrie, Pierre Vacher, Anne-Lise Develle, Emilie Chalmin, Fayçal Soufi, Nathalie Feuillet

Published: 2020-10-22
Subjects: Geochemistry, Oceanography, Sedimentology

The Lesser Antilles are a densely populated and a very touristic region exposed to many short-term hazards such as hurricanes and tsunamis. However, the historical catalog of these events is too short to allow risk assessment and return period estimations, and it needs to be completed with long-term geological records. Two sediment cores were sampled in March 2018 in a small coastal lagoon on [...]

Mercury stable isotope composition of seawater suggests important net gaseous elemental mercury uptake

Martin Jiskra, Lars-Eric Heimburger-Boavida, Marie-Maelle Desgranges, Mariia Petrova, Aurelie Dufour, Beatriz Ferreira-Araujo, Jeremy Masbou, Jerome Chmeleff, Melilotus Thyssen, David Point

Published: 2020-08-29
Subjects: Earth Sciences, Environmental Sciences, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

Human exposure to toxic mercury (Hg) is dominated by the consumption of seafood. Earth system models suggest that Hg in marine ecosystems is supplied by Hg(II) deposition, with a 3x smaller contribution from gaseous Hg(0) uptake, and that photochemical reduction of marine Hg(II) drives important Hg(0) evasion to the atmosphere. Observations of marine Hg(II) deposition and gas exchange are sparse [...]

Identifying and correcting the World War 2 warm anomaly in sea surface temperature measurements

DUO CHAN, Peter Huybers

Published: 2020-08-20
Subjects: Climate, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

Most foregoing estimates of historical sea surface temperature (SST) feature warmer global-average SSTs during World War 2 well in excess of climate-model predictions. This warm anomaly, referred to as the WW2WA, was hypothesized to arise from incomplete corrections of biases associated with rapid changes in measurement instruments and protocols. Using linear mixed-effects methods we confirm [...]

A general expression for wave-induced sediment bypassing of an isolated headland

Robert Jak McCarroll, Gerd Masselink, Nieves G. Valiente, Erin V. King, Timothy Scott, Christopher Stokes, Mark Wiggins

Published: 2020-07-21
Subjects: Earth Sciences, Engineering, Geomorphology, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Other Engineering, Physical Sciences and Mathematics

Accurate knowledge of the sediment budget of a coastal cell is necessary for coastal management and predicting long-term coastal change. An important component in the sediment budget of many wave-dominated embayed coastlines is the amount of sediment that bypasses rocky headlands, which present partial barriers to alongshore transport. Despite a recent surge in research interest in headland [...]


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