• Issue
    Volume 122, Issue 5
    3501-4477
    May 2017

Issue Information

Free Access

Issue Information

  • Pages: 3501-3504
  • First Published: 27 June 2017

Introduction to a Special Section

Free Access

Targeted ocean sampling guidance for tropical cyclones

  • Pages: 3505-3518
  • First Published: 25 April 2017
Key Points

  • Assimilation of AXBT observations has large impacts on reducing forecast errors in the COAMPS-TC prediction of ocean temperature
  • The impact of adjoint-based targeted ocean observation are sensitive to the prestorm ocean conditions, TC-induced cold wake, and the TC model forecast track errors

Research Articles

Free Access
Highlight

Downstream evolution of the Kuroshio's time-varying transport and velocity structure

  • Pages: 3519-3542
  • First Published: 11 March 2017
Key Points

  • Kuroshio mean transport increases by 50% between Luzon and Taiwan, primarily via a downstream increase in thickness of the poleward flow
  • Observations suggest a deep cyclonic recirculation east of Taiwan, which arises because the mean poleward flow impinges on the Ilan Ridge
  • Transport and velocity structure east of Taiwan are modulated by arrivals of deep-reaching eddies and their interactions with the ridges

Free Access
Highlight

Bio-optical anomalies in the world's oceans: An investigation on the diffuse attenuation coefficients for downward irradiance derived from Biogeochemical Argo float measurements

  • Pages: 3543-3564
  • First Published: 23 March 2017
Key Points

  • Different optical behaviors among oceanic regions as observed from diffuse attenuation coefficients within the first optical depth
  • High content of colored dissolved organic matter causes the deviation of most open ocean waters from existing bio-optical models
  • Bio-optical anomalies as proxies for revealing the occurrence of specific events and related biogeochemical processes

Free Access

Transport and thermohaline variability in Barrow Canyon on the Northeastern Chukchi Sea Shelf

  • Pages: 3565-3585
  • First Published: 28 March 2017
Key Points

  • Transport variations are controlled by Chukchi and Bering seas winds, which allow statistically robust transport hindcasts
  • Hindcasts define an climatological annual transport cycle that is downcanyon in summer, upcanyon in fall, and zero in winter
  • Canyon water properties and upcanyon and downcanyon transport event durations vary seasonally

Free Access

A statistical study on the subthermocline submesoscale eddies in the northwestern Pacific Ocean based on Argo data

  • Pages: 3586-3598
  • First Published: 31 March 2017
Key Points

  • Submesoscale STEs were identified using 14 years of Argo T/S data in the northwestern Pacific Ocean
  • Statistical characteristics and spatial-temporal distributions of these submesoscale STEs were revealed
  • The origination, generation mechanism, and contribution to water subduction of these submesoscale STEs were discussed

Open Access
Highlight

An idealized study of near equatorial river plumes

  • Pages: 3599-3620
  • First Published: 31 March 2017
Key Points

  • Near equatorial river plumes can be characterized as beta-plumes
  • Eddy merging arrests the decay of the plume against mixing effects
  • Freshwater discharges on stratified basins generate cyclones that pump saltier water to the surface thus eroding the low-salinity signal

Free Access

Impacts of oil spills on altimeter waveforms and radar backscatter cross section

  • Pages: 3621-3637
  • First Published: 04 April 2017
Key Points

  • Confirmed the impact of oil spills on satellite altimetry measured waveforms
  • Quantified the variation of altimetry sigma0 as a function of oil thickness, wind speed, and radar band
  • Altimeter data can certainly be used as a complementary data set to validate and delineate thick oil cover

Free Access

Interannual surface salinity on Northwest Atlantic shelf

  • Pages: 3638-3659
  • First Published: 23 March 2017
Key Points

  • Spatially coherent interannual SSS encompasses the Scotia-to-Hatteras NW Atlantic shelf region
  • Salty and warm events occur coincident with east-southeast wind anomalies and weakening of both branches of the Scotian Shelf Current
  • Salt advection by anomalous SSC is the primary driver that regulates the transport of fresh/cold water from high latitudes

Free Access

The wave-driven current in coastal canopies

  • Pages: 3660-3674
  • First Published: 28 March 2017
Key Points

  • Submerged canopies under surface waves generate a strong mean current in the direction of wave propagation
  • The maximum current speed (at the top of the canopy) increases with vertical orbital excursion and canopy density
  • Characterization of this current allows an enhanced predictive capability for residence time in coastal canopies

Free Access

The role of ocean-atmosphere interaction in Typhoon Sinlaku (2008) using a regional coupled data assimilation system

  • Pages: 3675-3695
  • First Published: 07 April 2017
Key Points

  • Strongly coupled atmosphere-ocean data assimilation system was developed
  • The coupled assimilation system well reproduced variations in in situ SST
  • Coupled assimilation contributes to the improvement of TC simulation

Free Access

How well does wind speed predict air-sea gas transfer in the sea ice zone? A synthesis of radon deficit profiles in the upper water column of the Arctic Ocean

  • Pages: 3696-3714
  • First Published: 07 February 2017
Key Points

  • We present previously overlooked details related to gas tracer budgets in the presence of sea ice
  • Radon-deficit estimates of k show statistically adequate fit to wind speed parameterizations, when measured in 100% open water
  • Radon-deficit estimates of k do not fit with wind speed parameterizations, when measured beneath sea ice cover

Free Access

Erosion of a California Undercurrent eddy by bottom topography

  • Pages: 3715-3735
  • First Published: 07 April 2017
Key Points

  • A mesoscale-resolving ocean hindcast simulation is analyzed
  • The erosion of a California Undercurrent eddy is reported
  • Strong eddy-topography interactions induce a sign change in the heat flux direction

Free Access

Seagrass blade motion under waves and its impact on wave decay

  • Pages: 3736-3752
  • First Published: 13 April 2017
Key Points

  • Wave decay over a model seagrass bed was measured in experiments that also involved blade motion imaging
  • The reduction in wave-energy dissipation due to vegetation motion depends on the Cauchy number
  • Scaling laws describing individual blade behavior are able to predict the reduction in wave decay over the meadow

Free Access

Spatial variability of upper ocean POC export in the Bay of Bengal and the Indian Ocean determined using particle-reactive 234Th

  • Pages: 3753-3770
  • First Published: 24 April 2017
Key Points

  • The (234)Th-based particulate organic carbon export fluxes showed high values in the equatorial Indian Ocean
  • On the other hand, intense remineralization of organic matter reduced carbon export in the Bay of Bengal
  • Region-specific refinement of models is required to better predict carbon export fluxes from surface productivity

Open Access

A new look at ocean ventilation time scales and their uncertainties

  • Pages: 3771-3798
  • First Published: 17 March 2017
Key Points

  • Eddy-resolving simulations quantifying ocean variability and biases from tracers are used to reinterpret temporal trends in ventilation
  • Ocean ventilation increased in southern subtropical gyres between mid-1990s and 2000s, while between mid-1990s and 2010s there was no trend
  • Observed age/ventilation changes are linked to a combination of natural cycles and climate change and there is regional variability

Free Access

Rip currents and alongshore flows in single channels dredged in the surf zone

  • Pages: 3799-3816
  • First Published: 23 March 2017
Key Points

  • Rip currents, feeder currents, and meandering alongshore currents were observed in single channels dredged in the surf zone
  • The model COAWST reproduces the observed circulation patterns, and is used to investigate dynamics for a wider range of conditions
  • A parameter based on breaking-wave-driven setup patterns and alongshore currents predicts offshore-directed flow speeds

Free Access

Seasonal cycle of cross-equatorial flow in the central Indian Ocean

  • Pages: 3817-3827
  • First Published: 16 March 2017
Key Points

  • Mean volume transport is southward across the equator in the central Indian Ocean in approximate Sverdrup balance
  • Meridional winds force northward surface flow above deeper southward flow to generate an equatorial roll in the surface layer
  • Surface Ekman convergence and thermocline geostrophic divergence are superimposed on annual variations in cross-equatorial flow

Open Access

Fjord light regime: Bio-optical variability, absorption budget, and hyperspectral light availability in Sognefjord and Trondheimsfjord, Norway

  • Pages: 3828-3847
  • First Published: 13 April 2017
Key Points

  • Euphotic depth decreases from outer to inner fjord sections
  • Light availability curves are V shaped in the turbid fjord sections and U shaped in others
  • Sognefjord and Trondheimsfjord exhibit bio-optical variability

Free Access

Modeling temperature inversion in southeastern Yellow Sea during winter 2016

  • Pages: 3848-3860
  • First Published: 21 April 2017
Key Points

  • Significant temperature inversion observed in southwestern YS in February 2016
  • Occurrence of large temperature inversion closely related to northwesterly wind burst.
  • Northward propagation of sea level elevation results in large temperature inversion

Free Access

Boussinesq modeling of wave-induced hydrodynamics in coastal wetlands

  • Pages: 3861-3883
  • First Published: 04 April 2017
Key Points

  • An improved formulation of vegetation drag in Boussinesq models was implemented
  • Modeled and validated wave setup and wave height attenuation on a vegetated slope in the laboratory
  • The validated model was applied to hurricane field conditions

Free Access

Flow variability within the Alaska Coastal Current in winter

  • Pages: 3884-3906
  • First Published: 28 March 2017
Key Points

  • Under winter storm winds, swift along-shelf nearly-barotropic flow was typically observed
  • Flow fluctuations were primarily driven by variations of the sea-surface gradient and not by local winds
  • Under weak winds, a cross-shelf density gradient developed that generated near-surface currents of about 20 cm s−1

Free Access

Strongly nonlinear internal solitons: Models and applications

  • Pages: 3907-3916
  • First Published: 13 April 2017
Key Points

  • Strongly nonlinear internal waves are often observed in the ocean. The weakly nonlinear models are inapplicable for these waves
  • Here a strongly nonlinear evolution equation based on approximate Hamiltonian is suggested and applied to non-stationary internal waves
  • Comparison with numerical calculations and the available experimental data confirms applicability of this approach to oceanic processes

Free Access

Impact of sea level rise on tidal range in Chesapeake and Delaware Bays

  • Pages: 3917-3938
  • First Published: 21 April 2017
Key Points

  • Tidal range in Chesapeake and Delaware Bays decreases under sea level rise if low-lying land is allowed to flood
  • Increased dissipation in shallow water and newly inundated areas results in smaller tidal range
  • Hardening shorelines to prevent overland inundation cause tidal range to increase with rising sea level

Free Access

Nonbreaking wave-induced mixing in upper ocean during tropical cyclones using coupled hurricane-ocean-wave modeling

  • Pages: 3939-3963
  • First Published: 13 April 2017
Key Points

  • Evaluation of nonbreaking wave parameterization in coupled hurricane-ocean-wave model
  • Increased SST and enhanced mixed layer depth due to nonbreaking wave turbulence during hurricanes
  • Rapid response of increased wave heights to strong winds while delay in maximum SST cooling by a lag of 10–15 h

Free Access

Characterizing frontal eddies along the East Australian Current from HF radar observations

  • Pages: 3964-3980
  • First Published: 13 April 2017
Key Points

  • Cyclonic eddies occur frequently along the East Australian Current (30°S) on average every 7 days over a 12 month period
  • Frontal eddies with high Rossby number (0.6–1.9) and inshore radius ∼10 km propagate downstream all year round at 0.3–0.4 m/s
  • Cyclonic frontal eddies influence biology through vertical uplift favoring local production or entrainment of productive water over 100s of km

Free Access

Energy-optimal path planning in the coastal ocean

  • Pages: 3981-4003
  • First Published: 21 April 2017
Key Points

  • Fundamental energy-optimal path planning, rigorously utilizing realistic multiscale ocean forecasts
  • Using stochastic optimization showcased energy-optimal paths in data-assimilative simulations
  • Analyzed effects of tides, wind events, jets, shelfbreak front, and local circulations on the paths

Free Access

Warm water pathways toward Nioghalvfjerdsfjorden Glacier, Northeast Greenland

  • Pages: 4004-4020
  • First Published: 24 April 2017
Key Points

  • The shelf bathymetry is sufficiently deep to provide a pathway for Atlantic waters toward the 79NG
  • Warmest waters exceeding 1°C found at the bottom of the 79NG cavity originate from the Norske Trough
  • A boundary current carries warm waters via Norske Trough toward the 79NG

Free Access

Spatial patterns of mixing in the Solomon Sea

  • Pages: 4021-4039
  • First Published: 25 April 2017
Key Points

  • Within isopycnal layers dissipation varies by at least 2 orders of magnitude in the Solomon Sea
  • Dissipation is maximum in the surface and decreases by 2–3 orders of magnitude by 2000 m depth
  • Dissipation is seasonally variable, particularly in the thermocline

Free Access

Tide-induced residual circulation in a bay with laterally asymmetric depth

  • Pages: 4040-4050
  • First Published: 27 April 2017
Key Points

  • Residual circulation in an asymmetric bay is calculated by numerical and analytical models
  • Both models show a closed gyre above the wider shoal
  • The maximum inward residual current is shifted toward the wider shoal

Free Access

Intraseasonal-to-semiannual variability of sea-surface height in the astern, equatorial Indian Ocean and southern Bay of Bengal

  • Pages: 4051-4067
  • First Published: 27 April 2017
Key Points

  • 30–60 day SSH variability is strong in the southern BoB and along the coast of Sumatra
  • Eddies propagating from the east play a primary role in SSH variability east of Sri Lanka, indicating the importance of nonlinear processes
  • In the southern BoB, the n = 2 mode is dominant at 180 days, due to basin resonance and strong wind forcing

Free Access

Air-sea heat flux climatologies in the Mediterranean Sea: Surface energy balance and its consistency with ocean heat storage

  • Pages: 4068-4087
  • First Published: 21 January 2017
Key Points

  • Heat flux in the Mediterranean Sea
  • Net air-sea heat flux bias
  • Physical constraint on Qnet

Free Access

Behavior of a wave-driven buoyant surface jet on a coral reef

  • Pages: 4088-4109
  • First Published: 07 March 2017
Key Points

  • Reef-ocean temperature gradients are important in regulating reef-ocean exchange
  • Substantial recirculation of wave-driven jets exiting reef passes can occur
  • Alongshore velocity is important in determining amount of jet recirculation

Open Access

The 2014 Lake Askja rockslide-induced tsunami: Optimization of numerical tsunami model using observed data

  • Pages: 4110-4122
  • First Published: 23 March 2017
Key Points

  • Unique field data set on joint landslide deposit and tsunami runup presented
  • First model to show that frequency dispersion is needed to closely reproduce runup field data
  • Optimization procedure used to retrofit the likely landslide dynamics

Free Access

Observation-based parameterization of air-sea fluxes in terms of wind speed and atmospheric stability under low-to-moderate wind conditions

  • Pages: 4123-4142
  • First Published: 31 March 2017
Key Points

  • The turbulent fluxes through air-sea interface including momentum, sensible heat, and water vapor are systematically observed and analyzed
  • CDN, CHN, and CEN decrease when wind speed less than 5 m/s. CDN keeps constant then increases with wind speed. CHN and CEN remain constant
  • A new parameterization model is proposed as a function of Richardson number, which is free of the MOST and self-correlation

Free Access
Highlight

Short-crested waves in the surf zone

  • Pages: 4143-4162
  • First Published: 13 April 2017
Key Points

  • Short-crested waves generated by intersecting wave trains are numerically modeled by GPUSPH
  • Wave-current and wave-wave interactions drive enhanced wave amplitude diffraction and multiple nearshore circulation cells and vortices
  • Short-crested wave breaking generates vorticity, verified by waves with a limited number of components, but also directional wave spectra

Open Access

Subtidal circulation in a deep-silled fjord: Douglas Channel, British Columbia

  • Pages: 4163-4182
  • First Published: 15 February 2017
Key Points:

  • An annual 3 month long deep water renewal replenishes the deep basin water in Douglas Channel
  • The observed landward net volume flux suggests the importance of the complex channel network to the system
  • Counter-wind current velocity response is observed at 100–120 m depth

Free Access

A modeling study of the impact of major storms on seabed shear stress and sediment transport on the Grand Banks of Newfoundland

  • Pages: 4183-4216
  • First Published: 02 March 2017
Key Points

  • Storms enhance bed shear velocity by >5 times and cause significant transport of medium sand over the entire Grand Banks
  • The direction of sediment transport rotates clockwise progressively during the passage of storms due to the clockwise rotation of the tidal and storm-induced currents
  • Maximum shear stress and peak transport typically occur on central and southeastern Grand Bank but transport patterns show strong spatial and temporal variability

Open Access

Generation of exchange flows in estuaries by tidal and gravitational eddy viscosity-shear covariance (ESCO)

  • Pages: 4217-4237
  • First Published: 20 March 2017
Key Points

  • We generalize and further systematize theory on exchange flows through eddy viscosity-shear covariance (ESCO)
  • We identify a new exchange flow contribution due to gravitational eddy viscosity-shear covariance (g-ESCO)
  • g-ESCO is typically of a similar importance as gravitational circulation and tidal ESCO (previously also called tidal straining circulation)

Free Access
Highlight

New insights on tsunami genesis and energy source

  • Pages: 4238-4256
  • First Published: 20 March 2017
Key Points

  • A set of large-scale laboratory experiment with a piston wavemaker is conducted to replicate the tsunami energy ratio associated with earthquake-induced seafloor slope displacements
  • The laboratory experiment reveals a three-dimensional nature of tsunami generation mechanism, differing from the vertically forced tsunami theory
  • A new source energy formulation with both potential and kinetic energy for tsunami generation is proposed and applied to scale tsunamis

Free Access

Coastal-trapped behavior of the diurnal internal tide at O'ahu, Hawai'i

  • Pages: 4257-4273
  • First Published: 24 April 2017
Key Points

  • Model and observations show the diurnal internal tide propagates clockwise around O'ahu as an imperfectly trapped wave
  • This coastal trapping has consequences for the island's nearshore variability
  • Imperfect trapping of superinertial internal tides may be an overlooked phenomenon at other locations worldwide

Free Access

Short-term variability of aragonite saturation state in the central Mid-Atlantic Bight

  • Pages: 4274-4290
  • First Published: 09 May 2017
Key Points

  • Large changes in surface water aragonite saturation state were observed off the Delaware and Chesapeake Bays over a short period of 10 days
  • Biological carbon removal and CO2 degassing largely affected the aragonite saturation state on the shelf
  • Physical processes were the dominant forces for large aragonite saturation state changes in the slope water

Free Access

Bay of Bengal salinity stratification and Indian summer monsoon intraseasonal oscillation: 1. Intraseasonal variability and causes

  • Pages: 4291-4311
  • First Published: 04 May 2017
Key Points

  • Intraseasonal variability of the mixed-layer depth (MLD) and barrier layer thickness (BLT) during MISO events is investigated
  • MISOs induce in-phase variations in MLD and isothermal layer depth, and variation of BLT is relatively small
  • MLD deepening is caused by wind stress through turbulent mixing and surface salinity change while the ILD deepening is driven by heat flux

Free Access
Highlight

Bay of Bengal salinity stratification and Indian summer monsoon intraseasonal oscillation: 2. Impact on SST and convection

  • Pages: 4312-4328
  • First Published: 11 March 2017
Key Points

  • In the BoB, the MISO induces intraseasonal SST variability primarily through surface heat flux forcing
  • The ocean salinity stratification has a strong control on SST but generally weak impact on convection of the MISO
  • Shallow MLD and thin barrier layer greatly enhance intraseasonal SST anomalies and amplify convection fluctuations of the MISO

Free Access

Isopycnal eddy mixing across the Kuroshio Extension: Stable versus unstable states in an eddying model

  • Pages: 4329-4345
  • First Published: 24 April 2017
Key Points

  • Cross-jet eddy mixing was compared for the stable and unstable states of the Kuroshio Extension
  • Mixing has significant spatiotemporal variability: both mean flow and eddies differ between the two states
  • Eddy mixing coefficients in coarse-resolution models should have spatiotemporal variations

Free Access

On the spatial coherence of the Atlantic Water inflow across the Nordic Seas

  • Pages: 4346-4363
  • First Published: 25 April 2017
Key Points

  • Change in the AW circulation across the Nordic Seas in the mid-1990s
  • The circulation change appears to be linked to a weakening of the southwesterly wind anomalies in the Norwegian Sea
  • Circulation change may be accompanied by increased heat transfer from Atlantic Water current to the interior of the Nordic Seas

Open Access

Importance of Ekman transport and gyre circulation change on seasonal variation of surface dissolved iron in the western subarctic North Pacific

  • Pages: 4364-4391
  • First Published: 03 May 2017
Key Points

  • Seasonal variation of dissolved Fe in the western subarctic North Pacific is studied using an OGCM coupled with simple biogeochemical model
  • Lateral advection and vertical mixing contribute comparably to the increase of dissolved Fe during winter
  • Ekman transport and upwelling/downwelling as well as the geostrophic current system is related to lateral advection process

Free Access

Tropical cyclone sensitivity to ocean coupling in the ECMWF coupled model

  • Pages: 4392-4412
  • First Published: 04 May 2017
Key Points

  • We have used the coupled ECMWF model to simulate a set of tropical cyclones in the North-western Pacific
  • The impact of coupling the atmosphere to the ocean is different for different TC's
  • We use TC Haiyan and TC Neoguri to illustrate the reasons for the different coupling impact

Free Access
Highlight

Wind-driven ocean dynamics impact on the contrasting sea-ice trends around West Antarctica

  • Pages: 4413-4430
  • First Published: 31 March 2017
Key Points

  • An ocean and sea-ice coupled model reproduced the contrasting sea-ice trends around West Antarctica during the past decades
  • In the East Pacific, enhanced Ekman upwelling and northward cold water transport helped summer-retreat and winter-expansion of sea-ice
  • In the Atlantic, enhanced Weddell Gyre and related meridional thermal gradient helped summer-expansion and winter-retreat of sea-ice

Free Access

Evaluation of anthropogenic influences on the Luhuitou fringing reef via spatial and temporal analyses (from isotopic values)

  • Pages: 4431-4443
  • First Published: 09 May 2017
Key Points

  • Isotopic values revealed strong anthropogenic influences on coral reefs
  • Hydrodynamic conditions coupled with human activities have profound implications for nutrient concentrations
  • There might be more inputs from terrestrial detritus and anthropogenic-derived discharges in dry seasons

Free Access

The formation processes of phytoplankton growth and decline in mesoscale eddies in the western North Pacific Ocean

  • Pages: 4444-4455
  • First Published: 15 May 2017
Key Points

  • The historical (2005–2013) ship-observed Chla in mesoscale eddies in western Pacific Ocean are composite
  • Sunlight and initially upwelled nutrients promotes the growth of phytoplankton in cold eddies
  • The upwelling/downwelling-induced nitrate flux accounts for a small percentage of the total nitrate flux after eddy formation

Free Access

The impact of storms and stratification on sediment transport in the Rhine region of freshwater influence

  • Pages: 4456-4477
  • First Published: 23 March 2017
Key Points

  • Net cross-shore transport results from the combination of three transport mechanisms that turn on and off in response to the forcing conditions
  • Barotropic transport at depth during storms results in net offshore transport. Baroclinic transport at depth during stratified periods results in onshore transport
  • Tidal plume fronts manifest as strong pulses of seaward transport at depth, presenting a dynamical component not observed in the far-field