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Water‐Mass Properties and Circulation in the Deep and Abyssal Philippine Sea

  •  31 May 2021

Key Points

  • Details of the Lower Circumpolar Deep Water's distribution in the Philippine Sea are presented

  • Deep currents transport Lower Circumpolar Deep Water through the Kyushu-Palau Ridge at 22.5°N–29.5°N

  • A notable warming trend (0.33 ± 0.19 × 10−3°C yr−1) is identified below 2,000 m of the deep Philippine Sea since 1990

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Dynamics of Tidal and Residual Currents Based on Coastal Acoustic Tomography Assimilated Data Obtained in Jiaozhou Bay, China

  •  31 May 2021

Key Points

  • Thirteen coastal acoustic tomography stations were deployed to obtain current field data in Jiaozhou Bay, China

  • Tidal and residual currents were obtained by data assimilation based on coastal acoustic tomography observations

  • Generation mechanisms for nonlinear and residual tidal currents in Jiaozhou Bay were demonstrated

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Influence of the Distortion of Vertical Wavenumber Spectra on Estimates of Turbulent Dissipation Using the Finescale Parameterization: Observations in the Antarctic Circumpolar Current

  •  27 May 2021

Key Points

  • Internal wave energy spectra in the Antarctic Circumpolar Current have 0.01 cpm vertical-wavenumber humps

  • The spectral hump is presumably caused by near-inertial or lee wave packets

  • Finescale parameterizations overestimate turbulent dissipation rates for such spectra if the rolloff wavenumber is not resolved

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Tidally Induced Temporal Variations in Growth of Young‐of‐the‐Year Pacific Cod in the Yellow Sea

  •  26 May 2021

Key Points

  • The early growth of Pacific cod was determined by otolith daily increment, which showed a signal similar to the fortnightly tidal cycle

  • Tidally induced growth variations have a lag of about eight days with the spring tide, probably due to digestion and growth

  • The tidal influence was stronger for Pacific cod after migrating into Yellow Sea Cold Water Mass, particularly during the settlement stage

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Time Dependent Flow of Atlantic Water on the Continental Slope of the Beaufort Sea Based on Moorings

  •  26 May 2021

Key Points

  • A short-lived “rebound jet” of Atlantic Water (AW) on the upper slope regularly follows wind-driven upwelling events in the Beaufort Sea

  • A total of 57 such events, lasting on average 3 days each, occurred over the 2 year measurement period

  • The onshore branch of the AW boundary current is impacted by local wind stress as well as wind stress curl in the Canada Basin

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Eddy Induced Trapping and Homogenization of Freshwater in the Bay of Bengal

  •  26 May 2021

Key Points

  • Freshwater from rivers is trapped in a long-lived cyclonic eddy in the north Bay of Bengal (BoB) during the postmonsoon season

  • Observations show a substantial increase in sea surface salinity (SSS) of trapped freshwater on the timescale of a month

  • Lagrangian tracer advection elucidates horizontal mixing across the eddy boundary

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Mixing Efficiency for Breaking Internal Solitary Waves

  •  26 May 2021

Key Points

  • Heuristic model to quantify mixing induced by breaking internal solitary waves (ISWs)

  • Experimental estimation of the change in the total background potential energy

  • Prediction of the mixing efficiency for breaking ISWs

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Issue Information

  •  24 May 2021
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Seasonal and Interannual Variability of the Meridional Overturning Circulation in the Subpolar North Atlantic Diagnosed From a High Resolution Reanalysis Data Set

  •  22 May 2021

Key Points

  • The transport between Greenland and Scotland is the major contributor to the strength of Meridional Overturning Circulation (MOC) in subpolar north Atlantic

  • The Irminger basin modulates the remarkable seasonality of MOC between Greenland and Scotland

  • Interannual variability of MOC between Newfoundland and Greenland is comparable to that between Greenland and Scotland

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Revisiting the Malvinas Current Upper Circulation and Water Masses Using a High‐Resolution Ocean Reanalysis

  •  21 May 2021

Key Points

  • The Malvinas Current is rather steady: Volume transport time series have little seasonality, no trend, and small relative standard deviations

  • The upper 900 m transport mean decreases from 40 Sv at 51°S to 35 Sv at 41°S indicating offshore leakage along the MC path

  • The Malvinas Plateau is a key region for water mass modification through eddy mixing and deep winter mixed layers

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Observations of SST‐induced wind perturbations in the Leeuwin Current

  •  2 June 2021

Key Points

  • Leeuwin Current SST perturbation causes significant wind speed and wind stress curl anomalies along the current core

  • Perturbation wind stress curl drives anomalous downwelling and would reduce surface chlorophyll a concentrations along the LC SST front

  • The relationships between perturbation SST and perturbation wind and their derivatives in the LC have obvious seasonal variations

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Assessing eddying (1/12°) ocean reanalysis GLORYS12 using the 14‐yr instrumental record from 59.5°N Section in the Atlantic

  •  1 June 2021

Key Points

  • Assessment of an eddying 1/12° ocean reanalysis with non-assimilated hydrographic observations along 59.5N in the Atlantic.

  • Reliable representation of the 0-700 m heat content but flaws in overflow waters due to a lack of deep observations.

  • Reliable reproduction outside the western boundary current of the major mesoscale eddy features that contribute to the meridional transport.

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Consistent Predictability of the Ocean State Ocean Model (OSOM) using Information Theory and Flushing Timescales

  •  1 June 2021

Key Points

  • This paper introduces the Ocean State Ocean Model (OSOM), a Regional Ocean Modeling System (ROMS) implementation focused on the Rhode Island region.

  • The predictability of the OSOM is evaluated using information theory and initial condition ensembles in summer and winter conditions.

  • The flushing time scales (freshwater and salinity) of Narragansett and Mt. Hope Bays are calculated and resemble the predictability timescales, indicating that predictability is largely governed by the estuarine circulation in this model.

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Regional Trends in Southern Ocean Eddy Kinetic Energy

  •  31 May 2021

Key Points

  • Eddy kinetic energy (EKE) computed from altimetry crossovers can well represent EKE changes in the Southern Ocean.

  • No coherent increase in EKE over all areas of the Southern Ocean was identified since 1993.

  • EKE in the Southern Ocean has increased since 1993 in one region that is downstream of the Campbell Plateau.

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Extensive remineralization of peatland‐derived dissolved organic carbon and ocean acidification in the Sunda Shelf Sea, Southeast Asia

  •  31 May 2021

Key Points

  • 70–80% of the dissolved organic carbon exported from the tropical peatlands is remineralized in the Sunda Shelf Sea

  • This drives a seasonal decline in pH by 0.1 and a net CO2 efflux of 2.4 – 4.9 mol m-2 yr-1 in the central Sunda Shelf

  • 20–30% of the peatland-derived dissolved organic carbon might be relatively refractory and exported to the open Indian Ocean

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Sub‐ice platelet layer physics: Insights from a mushy‐layer sea ice model

  •  30 May 2021

Key Points

  • A realistic sub-ice platelet layer emerges in a one-dimensional thermodynamic sea ice model when suitably forced

  • Key influences are heat loss to water column, thermal insulation by ice and snow, and brine convection between platelet crystals

  • The sub-ice platelet layer is stabilized by its high liquid content and isothermal character

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A census of eddies in the tropical eastern boundary of the Indian Ocean

  •  30 May 2021

Key Points

  • Eddies identified and quantified in a new comprehensive census for the Indo-Australian Basin

  • Newly identified hotspots for eddy activity identified in the eastern basin

  • More than 41% of eddies detected than in previous surveys

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Substantial Sea Surface Temperature cooling in the Banda Sea associated with the Madden‐Julian Oscillation in the boreal winter of 2015

  •  30 May 2021

Key Points

  • Substantial sea surface temperature cooling occurred in the Banda Sea associated with the 2015 boreal winter Madden-Julian Oscillation.

  • Enhanced vertical mixing associated with the MJO contributes more than surface heat flux for driving this extreme SST cooling.

  • Elevated thermocline associated with the 2015 strong El Niño is largely responsible for the intensified SST cooling.

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Generation of shoreward nonlinear internal waves south of the Hainan Island: SAR observations and numerical simulations

  •  28 May 2021

Key Points

  • Two types of shoreward nonlinear internal waves south of the Hainan Island are identified by analyzing multiple SAR images.

  • The two types of nonlinear internal waves have different source sites and generation mechanisms.

  • Background current can greatly affect the nonlinear evolution of the internal waves.

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Acquisition of the Significant Wave Height from CFOSAT SWIM Spectra through a Deep Neural Network and its Impact on Wave Model Assimilation

  •  27 May 2021

Key Points

  • A deep neural network (DNN) model is developed for the acquisition of significant wave heights from CFOSAT SWIM spectra.

  • Additional positive impacts are found in the assimilation of the SWIM box SWH from the DNN compared to the assimilation of nadir SWH only.

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EN4: Quality controlled ocean temperature and salinity profiles and monthly objective analyses with uncertainty estimates

Key Points

  • EN4 dataset of quality-controlled temperature and salinity profiles is described
  • Dataset covers 1900 to present and includes monthly objective analyses
  • A novel method is presented to estimate uncertainty in the objective analyses

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Observation of rogue wave holes in a water wave tank

Key Points

  • Experimental generation of rogue wave holes
  • Rogue waves holes within the framework of the nonlinear Schrodinger equation
  • Rogue wave holes modeled by the Peregrine soliton

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A Global Perspective on Microplastics

Key Points

  • The sources, behavior, fate, and effects of microplastics are inexplicably tied to those of their plastic product and macrodebris precursors, as well as the nanoplastics into which they fragment
  • Microplastic sampling and characterization methods are evolving, but their inadequacies still hamper efforts to evaluate the true extent of their presence and consequences in the built and natural environments
  • Microplastics are a global/multimedia phenomenon; hence, they cannot be adequately understood, or related concerns resolved, in the context of the marine environment alone or a single discipline

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Seasonal and interannual variability of the Eastern Tropical Pacific Fresh Pool

Key Points

  • Satellite SSS in synergy with complementary EO data allows studying the seasonal and interannual dynamics of the Eastern Pacific Fresh Pool
  • Fresh pool zonal displacements and links between surface and subsurface processes respond to freshwater fluxes, wind stress, and currents
  • Fresh pool interannual variability is related to ENSO phases, a maximal extension was reached in 2015 coinciding with a strong El Nino event

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Enhanced sea‐air CO2 exchange influenced by a tropical depression in the South China Sea

Key Points

  • Surface water diluted by heavy rain had low pCO2,sw
  • Passage of a tropical depression led to high pCO2,sw by eddy-driven uplifting
  • The depression turned local water from a carbon sink to a source temporarily

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Understanding Arctic Ocean Circulation: A Review of Ocean Dynamics in a Changing Climate

Key Points

  • Major features of Arctic Ocean circulation are reviewed and interpreted theoretically
  • Fundamental ocean dynamics are set in the context of a changing Arctic climate
  • We describe how Arctic dynamics might change in the future

Plain Language Summary

The Arctic region is experiencing the most rapid environmental changes on Earth, with unparalleled air temperature increases, a warming ocean, and melting permafrost, snow, and ice. The ocean is a central control via Arctic Ocean warming, freshening, and circulation dynamics that link to the sea ice, atmosphere, and terrestrial environment. Given the rapid pace of Arctic change, it is vital to take stock of present understanding of the ocean circulation to address knowledge gaps and make viable future predictions. Present understanding of the principal geophysical fluid dynamics of Arctic Ocean circulation is synthesized here, and we speculate on how the dynamics of the ocean-ice-atmosphere system might change in a warming Arctic.

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Role of Baroclinic Processes on Flushing Characteristics in a Highly Stratified Estuarine System, Mobile Bay, Alabama

Key Points

  • Baroclinic processes, particularly the density-driven circulation, are important in the flushing of the stratified estuary
  • Without the baroclinic processes, the flushing time can be overestimated by onefold under low to moderate river discharge conditions
  • This is the first study to summarize the full three-dimensional general circulation in Mobile Bay, whose pattern is primarily regulated by river discharge and modulated by wind forcing

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