• Issue

    Journal of Geophysical Research: Oceans: Volume 124, Issue 2

    789-1378
    February 2019

Issue Information

Free Access

Issue Information

  • Pages: 789-790
  • First Published: 18 March 2019

Research Articles

Free Access

Effects of Coastal Upwelling and Downwelling on Hydrographic Variability and Dissolved Oxygen in Mobile Bay

  • Pages: 791-806
  • First Published: 04 January 2019
Key Points

  • Heat flux observations highlight large differences in heat content associated with advection from offshore upwelling and downwelling events
  • Small thermal eddy diffusivity values are associated with stratification in the estuary
  • Advection of low dissolved oxygen water from the shelf into the estuary was observed in the shipping channel and near the estuary mouth

Free Access

Advancing Short-Term Forecasts of Ice Conditions in the Beaufort Sea

  • Pages: 807-820
  • First Published: 14 January 2019
Key Points

  • Ice concentration and thickness data collected in the Beaufort Sea in September–December 2015 were assimilated into a numerical model
  • The 24-hr forecast skill of the model was improved
  • Improvement is achieved by introducing ice thickness assimilation capabilty, flow-dependent correlations, and Gaussianization

Free Access

Significant Biologically Mediated CO2 Uptake in the Pacific Arctic During the Late Open Water Season

  • Pages: 821-843
  • First Published: 10 January 2019
Key Points

  • We evaluate biological carbon cycling in the Pacific Arctic during the late open water season
  • ∆O2/Ar and ΔpCO2 observations suggest an important role for late season biological activity toward maintaining an ocean carbon sink
  • High mesoscale variability in biological metabolism inferred from O2/Ar suggests localized and likely episodic nutrient supply

Free Access

The Beaufort Gyre Extent, Shape, and Location Between 2003 and 2014 From Satellite Observations

  • Pages: 844-862
  • First Published: 16 January 2019
Key Points

  • Dynamic ocean topography shows the Beaufort Gyre area expanded at a rate of 53,000 km2/year over 2003-2014, with elevated gyre center from 2007–2012
  • Gyre strength is determined by the intensity of the Beaufort Sea High, while its area is also determined by the Beaufort Sea High location
  • Shallow bathymetry of Chukchi Plateau restricts westward expansion, resulting in asymmetry and potential changes to gyre dynamics

Free Access

Circulation of Pacific Winter Water in the Western Arctic Ocean

  • Pages: 863-881
  • First Published: 16 January 2019
Key Points

  • PWW is a deeper freshwater source in contrast to the wind-driven Ekman convergence of freshwater in the surface layer of the western Arctic
  • An anticyclonic pathway of PWW is identified from hydrographic and mooring data over the years 2002-2016
  • The upper and lower bounds of PWW show a significantly different deepening rate at the edge of the Beaufort Gyre due to the advection of PWW

Free Access

Tracing Atlantic Waters Using 129I and 236U in the Fram Strait in 2016

  • Pages: 882-896
  • First Published: 16 January 2019
Key Points

  • In 2016, inflowing Atlantic waters to the Arctic Ocean have lower 129I and 236U concentrations than outflowing Arctic waters
  • High 129I and 236U in outflowing surface Arctic waters indicate substantial influence from the Norwegian Coastal Current
  • Combination of 129I and 236U allowed for an estimation of transit times for Atlantic branches through the Arctic Ocean to the Fram Strait

Free Access

Wind Limits on Rain Layers and Diurnal Warm Layers

  • Pages: 897-924
  • First Published: 26 October 2018
Key Points

  • Rain layers were detected at values of U10 up to 9.8 m s−1, while diurnal warm layers were only detected at U10 < 7.6 m s−1 (99th percentile values)
  • The formation and persistence of stable layers at depths ≤ 5 m were well estimated by U10 and the surface buoyancy flux, B
  • Rain layers (and their combinations with diurnal warm layers) formed often in disturbed and active MJO periods before westerly wind bursts

Open Access

Green Icebergs Revisited

  • Pages: 925-938
  • First Published: 10 January 2019
Key Points

  • Icebergs of marine ice vary in color from blue to green
  • The color is probably caused more by iron oxides than by dissolved organic carbon
  • The color may indicate the ability of icebergs to deliver iron as a nutrient

Open Access

Short-Term Variations in the Surface Upwelling off Northeastern Taiwan Observed via Satellite Data

  • Pages: 939-954
  • First Published: 18 January 2019
Key Points

  • A gradient-based edge detection algorithm is proposed for monitoring short-term surface upwelling processes via SST data
  • The features observed by Himawari-8 are quantitatively analyzed and verified using 8 years of combined satellite data
  • A preliminary discussion shows that the processes may be caused by the collective effects of multiple dynamical mechanisms

Free Access

The Generation of Overtides in Flow Around a Headland in a Low Inflow Estuary

  • Pages: 955-980
  • First Published: 06 January 2019
Key Points

  • Constricted flow around a headland results in elevated horizontal and vertical velocity shear in the water column, especially at the surface
  • Gyres induce quarter-diurnal patterns in velocity
  • Stress divergence, through bottom friction and other mechanisms, in addition to advection influence quarter-diurnal overtides

Free Access

Meridional Heat and Salt Transport Across the Subantarctic Front by Cold-Core Eddies

  • Pages: 981-1004
  • First Published: 28 January 2019
Key Points

  • We characterize for the first time the physical structure of a Subantarctic Front cold-core eddy, south of Tasmania in the Southern Ocean
  • Long-lived cold-core eddies transport about 21% of the required meridional heat flux across the Subantarctic Front
  • Previous studies have underestimated the total heat and salt content transport by cold-core eddies due to limited observations

Free Access

Effects of Locally Generated Wind Waves on the Momentum Budget and Subtidal Exchange in a Coastal Plain Estuary

  • Pages: 1005-1028
  • First Published: 28 January 2019
Key Points

  • Wind stresses in shallow coastal plain estuaries depend on wave age, bathymetry, and fetch
  • Subtidal bay-ocean exchange is modulated by wind waves, wind direction, tidal residual flows, and wind-driven Stokes drift
  • Wave breaking forces in a swell-sheltered bay were negligible except on shallow, steeply sloping ridges

Free Access

Processing Choices Affect Ocean Mass Estimates From GRACE

  • Pages: 1029-1044
  • First Published: 04 February 2019
Key Points

  • Published ocean mass rates from GRACE differ by up to more than 1 mm/year globally and for individual ocean basins
  • The main reasons are (1) how different techniques correct for GIA and (2) inconsistent restoring of the background atmosphere-ocean models
  • We provide a reconciled range of ocean mass rates (1.4-1.8 mm/s depending on analysis interval) that agrees within 0.1 mm/year across methods

Free Access

Formation and Removal of a Coastal Flood Deposit

  • Pages: 1045-1062
  • First Published: 05 January 2019
Key Points

  • A flood of the Elwha River generated near-bed coastal sediment concentrations of >10 g/L and deposited >15 cm of muddy sand in 1 day
  • Despite high fluvial-sediment concentrations, gravity-flow processes occurred for less than 2 hr
  • The deposit was completely eroded within 3 weeks, highlighting the difficulty of preserving event records in strongly tidal systems

Free Access

The Effect of Internal Variability on Ocean Temperature Adjustment in a Low-Resolution CESM Initial Condition Ensemble

  • Pages: 1063-1073
  • First Published: 30 January 2019
Key Points

  • Ocean internal variability is important when evaluating ocean variables
  • Ocean adjustment time scales are faster in the Atlantic than the Pacific due to basin dynamics
  • Gridded contours of time scales reflect general ocean circulation patterns

Free Access

Spatial Distribution and Biogeochemical Cycling of Dimethylated Sulfur Compounds and Methane in the East China Sea During Spring

  • Pages: 1074-1090
  • First Published: 11 December 2018
Key Points

  • Spatial distributions of dimethylated sulfur compounds and CH4 were measured, and the controlling factors were discussed
  • DMSP was used by bacteria for potential production of CH4 under certain conditions
  • Atmospheric DMS concentrations were measured for the first time, and sea-air fluxes of DMS and CH4 were estimated

Free Access

New Hydrographic Measurements of the Upper Arctic Western Eurasian Basin in 2017 Reveal Fresher Mixed Layer and Shallower Warm Layer Than 2005–2012 Climatology

  • Pages: 1091-1114
  • First Published: 25 January 2019
Key Points

  • Autonomous profilers provide an extensive physical and biogeochemical characterization of the western Eurasian Basin upper 350 m in 2017
  • The western Eurasian Basin exhibits a fresher surface layer and shallower warm Atlantic Water layer in 2017 than in 2005-2012
  • Mercator Ocean operational model outputs bring insights on the observed mesoscale structures in the halocline and warm layer

Free Access

Seasonal and Spatial Variations of the M2 Internal Tide in the Yellow Sea

  • Pages: 1115-1138
  • First Published: 30 January 2019
Key Points

  • The M2 internal tides in the Yellow Sea are numerically simulated and show significant spatial and seasonal variability
  • Stratification has a crucial impact on the generation, propagation, and dissipation of internal tides
  • Internal tidal-induced mixing and its seasonality are nonnegligible in the Yellow Sea

Free Access

Subtropical Mode Water and Permanent Pycnocline Properties in the World Ocean

  • Pages: 1139-1154
  • First Published: 04 February 2019
Key Points

  • In each subtropical basin, the stratification pattern of a mode water pycnostad overlying a permanent pycnocline exists continuously throughout the gyre
  • The pycnocline has a double-bowl pattern with two deep centers colocated with thick mode waters and shallower in the center of the gyre
  • The North Atlantic subtropical permanent pycnocline and mode waters are much deeper, thicker, and less stratified than those in other gyres

Free Access

Model-Derived Uncertainties in Deep Ocean Temperature Trends Between 1990 and 2010

  • Pages: 1155-1169
  • First Published: 28 January 2019
Key Points

  • We present a novel framework for estimating the uncertainties in deep ocean heat content trends using models
  • Biases due to infrequent sampling in time and space lead to largest errors between 2,000 and 3,000 m
  • There are substantial biases in regional change estimates calculated from hydrographic style sampling

Free Access

Long-Term Trends in Phytoplankton Chlorophyll a and Size Structure in the Benguela Upwelling System

  • Pages: 1170-1195
  • First Published: 18 January 2019
Key Points

  • Long-term trends showed linear increases in Chla and microphytoplankton in the Northern Benguela
  • Chla and microphytoplankton on the Southern Benguela shelf showed small long-term decreases
  • Chla and microphytoplankton showed long-term increases in summer but decreased in autumn, winter, and spring on the Agulhas Bank shelf

Free Access

A Wedge Mechanism for Summer Surface Water Inflow Into the Ross Ice Shelf Cavity

  • Pages: 1196-1214
  • First Published: 28 January 2019
Key Points

  • Summer surface water inflow is regularly seen in the Ross Ice Shelf cavity close to the front
  • Observations show a less saline wedge that curves isopycnals and guides flow of surface waters under the Ross Ice Shelf
  • The wedge in the Western Ross Sea is likely formed from ice shelf front meltwater

Open Access

Parameterizing Sea Surface Temperature Cooling Induced by Tropical Cyclones: 1. Theory and An Application to Typhoon Matsa (2005)

  • Pages: 1215-1231
  • First Published: February 2019
Key Points

  • We developed a fast and effective parameterization scheme for TC-induced SST cooling that can be used in atmospheric TC prediction models
  • This scheme includes vertical mixing, advection, and SST recovery for given sea surface height anomalies and ocean subsurface temperature
  • This scheme is evaluated through numerical simulations of Typhoon Matsa (2005) and validated against remote sensing data

Open Access

Parameterizing Sea Surface Temperature Cooling Induced by Tropical Cyclones: 2. Verification by Ocean Drifters

  • Pages: 1232-1243
  • First Published: 31 January 2019
Key Points

  • We analyzed sea surface responses to tropical cyclone passage using SST and ocean current data from 57 buoy drifters and satellite data
  • Three different sea surface responses in terms of the starting time, duration, strength, and rate of SST cooling and ocean currents are found
  • All the three response modes are well parameterized by the SST cooling scheme, when verified against the drifters-measured data

Free Access

The Initial Condition Errors Occurring in the Indian Ocean Temperature That Cause “Spring Predictability Barrier” for El Niño in the Pacific Ocean

  • Pages: 1244-1261
  • First Published: 30 January 2019
Key Points

  • Exploring the Indian Ocean sea temperature errors
  • Identifying the initial errors that frequently cause spring predictability barrier for Pacific El Niño
  • Exploring the evolutionary mechanism of such errors and its implication to El Niño predictions

Free Access

Distribution Patterns of Picosized and Nanosized Phytoplankton Assemblages in the East China Sea and the Yellow Sea: Implications on the Impacts of Kuroshio Intrusion

  • Pages: 1262-1276
  • First Published: February 2019
Key Points

  • Four phytoplankton assemblages in the East China Sea and the Yellow Sea were studied using flow cytometry
  • Distribution pattern of Prochlorococcus in spring well indicated the intrusion of Kuroshio in the East China Sea
  • Kuroshio intrusion could affect oceanographic and ecological processes in the coastal waters adjacent to the Changjiang River estuary

Free Access

Response of the Arctic Marine Inorganic Carbon System to Ice Algae and Under-Ice Phytoplankton Blooms: A Case Study Along the Fast-Ice Edge of Baffin Bay

  • Pages: 1277-1293
  • First Published: 15 January 2019
Key Points

  • An ice algae bloom beneath landfast sea ice did not impact DIC/pCO2, and is not expected to contribute to CO2 uptake from the atmosphere
  • Under ice phytoplankton blooms did significantly reduce DIC/pCO2, likely making the region a stronger sink for atmospheric CO2 at break-up
  • Arctic seas do not often experience supersaturation of pCO2 during the Arctic winter

Free Access

Relative Contributions of Bed Load and Suspended Load to Sediment Transport Under Skewed-Asymmetric Waves on a Sandbar Crest

  • Pages: 1294-1321
  • First Published: 14 January 2019
Key Points

  • Bed load and suspended load transport rates were measured on a sandbar crest under field-scale wave forcing
  • Total net transport rate was offshore-directed when suspended load dominated and onshore-directed when bed load dominated
  • Net bed load transport rates were well correlated with third moments of free-stream velocity

Free Access

Constraining Evaporation Rates Based on Large-Scale Sea Surface Transects of Salinity or Isotopic Compositions

  • Pages: 1322-1330
  • First Published: 26 January 2019
Key Points

  • A Lagrangian model is developed for changes in salinity and isotopic composition of a moving water column that undergoes net evaporation
  • The model is successfully applied to four oceanic transects
  • The observations provide reliable estimates of the model's new single-parameter – evaporation length

Open Access

Temporal and Spatial Variations of Cross-Shelf Nutrient Exchange in the East China Sea, as Estimated by Satellite Altimetry and In Situ Measurements

  • Pages: 1331-1356
  • First Published: 30 January 2019
Key Points

  • Nitrate transport shows a significant three-dimensional spatial structure with annual and interannual variations
  • Spatial structure of nitrate transport is determined by velocity in the horizontal and nitrate concentration in the vertical
  • Temporal variation in nitrate transport is mainly determined by velocity and particularly by its geostrophic component

Free Access

Estimation of Secondary Phytoplankton Pigments From Satellite Observations Using Self-Organizing Maps (SOMs)

  • Pages: 1357-1378
  • First Published: 07 February 2019
Key Points

  • The dynamic of phytoplankton communities can be observed while reconstructing accessory pigment variability from ocean color observations
  • Self-organizing maps allow an accurate retrieval of different phytoplankton pigment concentrations from satellite observations
  • A consistent global approach is established to estimate accessory pigment concentrations along with the uncertainties