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Publisher: AGU   (Total: 17 journals)   [Sort by number of followers]

 Showing 1 - 17 of 17 Journals sorted alphabetically Geochemistry, Geophysics, Geosystems       (Followers: 25, SJR: 2.439, h-index: 91) Geophysical Research Letters       (Followers: 101, SJR: 3.323, h-index: 185) Global Biogeochemical Cycles       (Followers: 12, SJR: 3.22, h-index: 136) J. of Advances in Modeling Earth Systems       (Followers: 4, SJR: 4.444, h-index: 18) J. of Geophysical Research : Atmospheres       (Followers: 105) J. of Geophysical Research : Biogeosciences       (Followers: 24) J. of Geophysical Research : Earth Surface       (Followers: 48) J. of Geophysical Research : Oceans       (Followers: 45) J. of Geophysical Research : Planets       (Followers: 101) J. of Geophysical Research : Solid Earth       (Followers: 42) J. of Geophysical Research : Space Physics       (Followers: 112) Paleoceanography       (Followers: 6, SJR: 3.067, h-index: 100) Radio Science       (Followers: 36, SJR: 1.072, h-index: 59) Reviews of Geophysics       (Followers: 33, SJR: 8.833, h-index: 107) Space Weather       (Followers: 16, SJR: 1.341, h-index: 26) Tectonics       (Followers: 12, SJR: 2.628, h-index: 96) Water Resources Research       (Followers: 74, SJR: 2.661, h-index: 144)
 Journal of Geophysical Research : Oceans   [45 followers]  Follow         Partially Free Journal    ISSN (Online) 2169-9291    Published by AGU  [17 journals]
• Quantifying the residual volume transport through a multiple-inlet system
in response to wind forcing: The case of the western Dutch Wadden Sea
• Authors: Matias Duran-Matute; Theo Gerkema, Maximiliano G. Sassi
PubDate: 2016-11-28T14:36:06.232328-05:
DOI: 10.1002/2016JC011807

• Tropical Cyclone asymmetry - development and evaluation of a new
parametric model
• Authors: M. Olfateh; David P. Callaghan, Peter Nielsen, Tom E. Baldock
PubDate: 2016-11-28T14:36:02.040704-05:
DOI: 10.1002/2016JC012237

• Large-eddy simulation of wave-breaking induced turbulent coherent
structures and suspended sediment transport on a barred beach
• Authors: Zheyu Zhou; Tian-Jian Hsu, Daniel Cox, Xiaofeng Liu
PubDate: 2016-11-28T14:35:58.920394-05:
DOI: 10.1002/2016JC011884

• The ocean mixed-layer under Southern Ocean sea-ice: Seasonal cycle and
forcing
• Authors: Violaine Pellichero; Jean-Baptiste Sallée, Sunke Schmidtko, Fabien Roquet, Jean-Benoît Charrassin
Abstract: The oceanic mixed-layer is the gateway for the exchanges between the atmosphere and the ocean; in this layer all hydrographic ocean properties are set for months to millennia. A vast area of the Southern Ocean is seasonally capped by sea-ice, which alters the characteristics of the ocean mixed-layer. The interaction between the ocean mixed-layer and sea-ice plays a key role for water-mass transformation, the carbon cycle, sea-ice dynamics, and ultimately for the climate as a whole. However, the structure and characteristics of the under-ice mixed-layer are poorly understood due to the sparseness of in-situ observations and measurements. In this study, we combine distinct sources of observations to overcome this lack in our understanding of the Polar Regions. Working with Elephant Seal-derived observations, ship-based and Argo float observations, we describe the seasonal cycle of the ocean mixed-layer characteristics and stability of the ocean mixed-layer over the Southern Ocean and specifically under sea-ice. Mixed-layer heat and freshwater budgets are used to investigate the main forcing mechanisms of the mixed-layer seasonal cycle. The seasonal variability of sea surface salinity and temperature are primarily driven by surface processes, dominated by sea-ice freshwater flux for the salt budget, and by air-sea flux for the heat budget. Ekman advection, vertical diffusivity and vertical entrainment play only secondary roles.Our results suggest that changes in regional sea-ice distribution and annual duration, as currently observed, widely affect the buoyancy budget of the underlying mixed-layer, and impact large-scale water-mass formation and transformation with far reaching consequences for ocean ventilation. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-28T14:35:55.289042-05:
DOI: 10.1002/2016JC011970

• Bottom-slope-induced net sheet-flow sediment transport rate under
sinusoidal oscillatory flows
• Authors: Jing Yuan; Zhiwei Li, O. S. Madsen
PubDate: 2016-11-28T14:35:52.278979-05:
DOI: 10.1002/2016JC011996

• Gulf of Maine salinity variation and its correlation with upstream Scotian
Shelf currents at seasonal and interannual time scales
• Authors: Hui Feng; Doug Vandemark, John Wilkin
PubDate: 2016-11-28T14:35:50.974821-05:
DOI: 10.1002/2016JC012337

• On the generation and evolution of internal solitary waves in the southern
Red Sea
• Authors: Daquan Guo; T. R. Akylas, Peng Zhan, Aditya Kartadikaria, Ibrahim Hoteit
PubDate: 2016-11-28T14:35:49.785171-05:
DOI: 10.1002/2016JC012221

• Role of wind in erosion–accretion cycles on an estuarine mudflat
• Authors: B.W. Shi; S.L. Yang, Y.P. Wang, G.C. Li, M.L. Li, P. Li, C. Li
Abstract: Wind is an important regulator of coastal erosion and accretion processes that have significant ecological and engineering implications. Nevertheless, previous studies have mainly focused on storm−generated changes in the bed level. This paper aims to improve the understanding of wind−induced erosion–accretion cycles on intertidal flats under normal (non−stormy) weather conditions using data that relates to the wave climate, near−bed 3D flow velocity, suspended sediment concentration, and bed−level changes on a mudflat at the Yangtze Delta front. The following parameters were calculated at 10−minute intervals over 10 days: the wind wave orbital velocity (Ûδ), bed shear stress from combined current–wave action, erosion flux, deposition flux, and predicted bed−level change. The time series of measured and predicted bed−level changes both show tidal cycles and a 10−day cycle. We attribute the tidal cycles of bed−level changes to tidal dynamics, but we attribute the 10−day cycle of bed−level changes to the interaction between wind speed/direction and neap−spring cyclicity. We conclude that winds can significantly affect bed−level changes in mudflats even during non−stormy weather and under macro−mesotidal conditions and that the bed−level changes can be predicted well using current–wave–sediment combined models. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-28T14:35:48.454254-05:
DOI: 10.1002/2016JC011902

• Effect of tides and source location on nearshore tsunami-induced currents
• Authors: Aykut Ayca; Patrick J. Lynett
Abstract: Here, we present the results of a numerical modeling study that investigates how event-maximum tsunami-induced currents vary due to the dynamic effects of tides and wave directivity. First, analyses of tide-tsunami interaction are presented in three harbors by coupling the tsunami with the tide, and allowing the initial tsunami wave to arrive at various tidal phases. We find that tsunami-tide interaction can change the event-maximum current speed experienced in a harbor by up to 25% for the events and harbors studied, and we note that this effect is highly site-specific. Second, to evaluate the effect of wave directionality on event-maximum currents, earthquakes sources were placed throughout the Pacific, with magnitudes tuned to create the same maximum near-coast amplitude at the harbor of study. Our analysis also shows that, for the harbor and sources examined, the effect of offshore directionality and tsunami frequency content has a weak effect on the event-maximum currents experienced in the harbor. The more important dependency of event-maximum currents is the near-harbor amplitude of the wave, indicating that event-maximum currents in a harbor from a tsunami generated by a large far-field earthquake may be reasonably well predicted with only information about the predicted local maximum tsunami amplitude. This study was motivated by the hope of constructing a basis for understanding the dynamic effects of tides and wave directivity on current-based tsunami hazards in a coastal zone. The consideration of these aspects is crucial and yet challenging in the modeling of tsunami currents. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-28T14:35:43.818112-05:
DOI: 10.1002/2016JC012435

• The impact of glacier meltwater on the underwater noise field in a glacial
bay
• Authors: Oskar Glowacki; Mateusz Moskalik, Grant B. Deane
PubDate: 2016-11-28T14:35:40.161873-05:
DOI: 10.1002/2016JC012355

• Factors controlling enhanced N2O concentrations over the southwestern
Indian shelf
• Authors: V. Sudheesh; G.V.M. Gupta, K.V. Sudharma, H. Naik, D.M. Shenoy, M. Sudhakar, S.W.A. Naqvi
Abstract: Repeat measurements of dissolved nitrous oxide (N2O) along two transects of the western continental shelf of India in 2012 revealed high concentrations of 45±32 nM (off Kochi) and 73±63 nM (off Mangalore) during the summer monsoon (SM). N2O concentrations increased non-linearly during the peak of the SM upwelling, when low O2 (
PubDate: 2016-11-28T14:35:38.617189-05:
DOI: 10.1002/2016JC012166

• Temporal variability of diapycnal mixing in the northern South China Sea
• Authors: Hui Sun; Qingxuan Yang, Wei Zhao, Xinfeng Liang, Jiwei Tian
Abstract: Temporal variability of diapycnal mixing over seven months in the northern South China Sea was examined based on McLane Moored Profiler observations from 850 to 2,200 m by employing a finescale parameterization. Intensified diffusivity exceeding the order of 10−3 m2/s in magnitude was found over the first half of Oct 2014, and from 2 Dec 2014 to 21 Jan 2015 (a typical wintertime). Strong internal tides and winds in winter were the likely candidates for the high-level diapycnal mixing in winter. As for the enhanced mixing during Oct 2014, we suspect the generation of near-bottom near-inertial waves through the interaction of mesoscale eddies and unique bottom topography was the cause. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-28T14:35:34.842422-05:
DOI: 10.1002/2016JC012044

• Hydrographic responses to regional covariates across the Kara Sea
• Authors: Jussi Mäkinen; Jarno Vanhatalo
Abstract: The Kara Sea is a shelf sea in the Arctic Ocean which has a strong spatiotemporal hydrographic variation driven by river discharge, air pressure and sea ice. There is a lack of information about the effects of environmental variables on surface hydrography in different regions of the Kara Sea. We use a hierarchical spatially varying coefficient model to study the variation of sea surface temperature (SST) and salinity (SSS) in the Kara Sea between years 1980 and 2000. The model allows us to study the effects of climatic (Arctic oscillation index, AO) and seasonal (river discharge and ice concentration) environmental covariates on hydrography. The hydrographic responses to covariates vary considerably between different regions of the Kara Sea. River discharge decreases SSS in the shallow shelf area and has a neutral effect in the northern Kara Sea. The responses of SST and SSS to AO show the effects of different wind and air pressure conditions on water circulation and hence on hydrography. Ice concentration has a constant effect across the Kara Sea. We estimated the average SST and SSS in the Kara Sea in 1980-2000. The average August SST over the Kara Sea in 1995-2000 was higher than the respective average in 1980-1984 with 99.9% probability and August SSS decreased with 77% probability between these time periods. We found a support that the winter season AO has an impact on the summer season hydrography, and temporal trends may be related to the varying level of winter season AO index. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-28T14:35:33.545373-05:
DOI: 10.1002/2016JC011981

• Turbulence-resolving, two-phase flow simulations of wave-supported gravity
flows: A conceptual study
• Authors: Celalettin Emre Ozdemir
PubDate: 2016-11-28T14:35:27.589828-05:
DOI: 10.1002/2016JC012061

• Formation of summer phytoplankton bloom in the northwestern Bay of Bengal
in a coupled physical-ecosystem model
• Authors: V. Thushara; P. N. Vinayachandran
PubDate: 2016-11-28T14:35:23.407116-05:
DOI: 10.1002/2016JC011987

• Seasonal variation of the Beaufort shelfbreak jet and its relationship to
Arctic cetacean occurrence
• Authors: Peigen Lin; Robert S. Pickart, Kathleen M. Stafford, G.W.K. Moore, Daniel J. Torres, Frank Bahr, Jianyu Hu
PubDate: 2016-11-16T16:06:01.205411-05:
DOI: 10.1002/2016JC011890

• Sea ice algae chlorophyll a concentrations derived from under-ice spectral
• Authors: Benjamin A. Lange; Christian Katlein, Marcel Nicolaus, Ilka Peeken, Hauke Flores
PubDate: 2016-11-16T16:05:54.138874-05:
DOI: 10.1002/2016JC011991

• Net primary productivity estimates and environmental variables in the
Arctic Ocean: An assessment of coupled physical-biogeochemical models
• Authors: Younjoo J. Lee; Patricia A. Matrai, Marjorie A. M. Friedrichs, Vincent S. Saba, Olivier Aumont, Marcel Babin, Erik T. Buitenhuis, Matthieu Chevallier, Lee de Mora, Morgane Dessert, John P. Dunne, Ingrid Ellingsen, Doron Feldman, Robert Frouin, Marion Gehlen, Thomas Gorgues, Tatiana Ilyina, Meibing Jin, Jasmin G. John, Jonathan Lawrence, Manfredi Manizza, Christophe Eugène Menkes, Coralie Perruche, Vincent Le Fouest, Ekaterina Popova, Anastasia Romanou, Annette Samuelsen, Jörg Schwinger, Roland Séférian, Charles A. Stock, Jerry Tjiputra, L. Bruno Tremblay, Kyozo Ueyoshi, Marcello Vichi, Andrew Yool, Jinlun Zhang
PubDate: 2016-11-14T14:18:16.980562-05:
DOI: 10.1002/2016JC011993

• Seasonal and interannual variability of the Arctic sea ice: A comparison
between AO-FVCOM and observations
• Authors: Yu Zhang; Changsheng Chen, Robert C. Beardsley, Guoping Gao, Jianhua Qi, Huichan Lin
Abstract: A high-resolution (up to 2 km), unstructured-grid, fully ice-sea coupled Arctic Ocean Finite-Volume Community Ocean Model (AO-FVCOM) was used to simulate the sea ice in the Arctic over the period 1978-2014. The spatial-varying horizontal model resolution was designed to better resolve both topographic and baroclinic dynamics scales over the Arctic slope and narrow straits. The model-simulated sea ice was in good agreement with available observed sea ice extent, concentration, drift velocity and thickness, not only in seasonal and interannual variability but also in spatial distribution. Compared with six other Arctic Ocean models (ECCO2, GSFC, INMOM, ORCA, NAME, and UW), the AO-FVCOM-simulated ice thickness showed a higher mean correlation coefficient of ∼0.63 and a smaller residual with observations. Model-produced ice drift speed and direction errors varied with wind speed: the speed and direction errors increased and decreased as the wind speed increased, respectively. Efforts were made to examine the influences of parameterizations of air-ice external and ice-water interfacial stresses on the model-produced bias. The ice drift direction was more sensitive to air-ice drag coefficients and turning angles than the ice drift speed. Increasing or decreasing either 10% in water-ice drag coefficient or 10° in water-ice turning angle did not show a significant influence on the ice drift velocity simulation results although the sea ice drift speed was more sensitive to these two parameters than the sea ice drift direction. Using the COARE 4.0 derived parameterization of air-water drag coefficient for wind stress did not significantly influence the ice drift velocity simulation. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-11T17:04:26.786954-05:
DOI: 10.1002/2016JC011841

• Seasonal cycle of near-bottom transport and currents in the northern Gulf
of California
• Authors: R. Navarro; M. López, J. Candela
Abstract: Seasonal cycles of near-bottom transport and temperature over the sills of the Northern Gulf of California, as well as surface geostrophic velocity anomalies, are presented. Transport at the sills, where overflows occur, is towards the head of the gulf all year round with maximum in October and minimum in June. Furthermore, transport is 180° out of phase with the surface geostrophic velocity across the northern gulf, consistent with the exchange being strongest in October. Seasonal cycles of near-bottom temperature and transport are also 180° out of phase, indicating that maximum water inflow is associated with the coolest water entering from the Pacific Ocean. Near-bottom temperature over the northern Ballenas Channel sill has a maximum in early August, which is more in phase with the surface temperature and consistent with intense mixing in the channel. Geostrophic velocity at the northern gulf is in phase with that near the mouth of the gulf, and approximately in phase with the seasonal heat input through the mouth, calculated previously by Beron-Vera and Ripa [2000]. Moreover, the maximum lower-layer, horizontal heat output of the Ballenas Channel occurs in November, approximately one month after the maximum transport through the San Lorenzo and Delfín sills. Therefore, heat loss results from the continuous near-bottom inflow of relatively cold water at both sills which bound the deepest basins of the northern gulf. Moreover, the mean and seasonal cycles of heat and mass fluxes in the deepest basins of the northern gulf are almost everywhere in opposite directions. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-11T17:04:12.638414-05:
DOI: 10.1002/2016JC012063

• GNSS-R nonlocal sea state dependencies: Model and empirical verification
• Authors: David D. Chen-Zhang; Christopher S. Ruf, Fabrice Ardhuin, Jeonghwan Park
PubDate: 2016-11-11T17:04:08.99925-05:0
DOI: 10.1002/2016JC012308

• Intrusive upwelling in the Central Great Barrier Reef
• Authors: Jessica A. Benthuysen; Hemerson Tonin, Richard Brinkman, Michael Herzfeld, Craig Steinberg
PubDate: 2016-11-11T17:04:04.859169-05:
DOI: 10.1002/2016JC012294

• Ocean mixing beneath Pine Island Glacier ice shelf, West Antarctica
• Authors: Satoshi Kimura; Adrian Jenkins, Pierre Dutrieux, Alexander Forryan, Alberto C. Naveira Garabato, Yvonne Firing
Abstract: Ice shelves around Antarctica are vulnerable to an increase in ocean-driven melting, with the melt rate depending on ocean temperature and the strength of circulations inside the ice-shelf cavities. We present measurements of velocity, temperature, salinity, turbulent kinetic energy dissipation rate and thermal variance dissipation rate beneath Pine Island Glacier ice shelf, West Antarctica. These measurements were obtained by CTD, ADCP and turbulence sensors mounted on an Autonomous Underwater Vehicle (AUV). The highest turbulent kinetic energy dissipation rate is found near the grounding line. The thermal variance dissipation rate increases closer to the ice-shelf base, with a maximum value found ∼0.5 m away from the ice. The observed dissipation rates near the ice are used to estimate basal melting of the ice shelf. We argue that our estimates of basal melting from dissipation rates are within a range of previous estimates of basal melting. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-11T17:04:03.134314-05:
DOI: 10.1002/2016JC012149

• Reconciling estimates of the ratio of heat and salt fluxes at the
ice-ocean interface
• Authors: T. Keitzl; J.-P. Mellado, D. Notz
Abstract: The heat exchange between floating ice and the underlying ocean is determined by the interplay of diffusive fluxes directly at the ice-ocean interface and turbulent fluxes away from it. In this study, we examine this interplay through direct numerical simulations of free convection. Our results show that an estimation of the interface flux ratio based on direct measurements of the turbulent fluxes can be difficult because the flux ratio varies with depth. As an alternative, we present a consistent evaluation of the flux ratio based on the total heat and salt fluxes across the boundary layer. This approach allows us to reconcile previous estimates of the ice–ocean interface conditions. We find that the ratio of heat and salt fluxes directly at the interface is 83 to 100 rather than 33 as determined by previous turbulence measurements in the outer layer. This can cause errors in the estimated ice-ablation rate from field measurements of up to 40% if they are based on the three-equation formulation. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-11T17:03:08.327637-05:
DOI: 10.1002/2016JC012018

• The diurnal cycle of sea-surface temperature and estimation of the heat
budget of the Mediterranean Sea
• Authors: S. Marullo; P. J. Minnett, R. Santoleri, M. Tonani
Abstract: The diurnal cycle in sea-surface temperature (SST) is reconstructed for the year 2013 by combining numerical model analyses and satellite measurements using Optimal Interpolation (OI). The method is applied to derive hourly Mediterranean SST fields using Spinning Enhanced Visible and Infrared Imager (SEVIRI) data and Mediterranean Forecasting System analyses (Copernicus Marine Environment Monitoring Service - Analysis and Forecast product). The evaluation of the Diurnal OI SST (
DOI SST) values against drifter measurements results in a mean bias of −0.1°C and a RMS of 0.4°C. The
DOI SST fields reproduce well the diurnal cycle in SST including extreme Diurnal Warming events as measured by drifting buoys. We evaluate the impact of resolving the SST diurnal cycle, including extreme events, on estimates of the heat budget of the Mediterranean Sea over an entire annual cycle. It results in the mean annual difference in the heat loss derived using SST's with and without diurnal variations of 4 Wm−2 with a peak of 9 Wm−2 in July. This value is comparable to several other sources of uncertainty in the calculation of the heat and water budgets of the Mediterranean Sea. The results are an important step towards reducing uncertainties in the “Mediterranean Sea Heat Budget Closure Problem. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-11T17:03:06.997545-05:

• Storm surge along the Pacific Coast of North America
• Authors: Peter D. Bromirski; Reinhard E. Flick, Arthur J. Miller
PubDate: 2016-11-11T17:03:03.014741-05:
DOI: 10.1002/2016JC012178

• Nitrous oxide during the onset of the Atlantic Cold Tongue
• Authors: D. L. Arévalo-Martínez; A. Kock, T. Steinhoff, P. Brandt, M. Dengler, T. Fischer, A. Körtzinger, H. W. Bange
Abstract: The tropical Atlantic exerts a major influence in climate variability through strong air-sea interactions. Within this region, the eastern side of the equatorial band is characterized by strong seasonality, whereby the most prominent feature is the annual development of the Atlantic Cold Tongue (ACT). This band of low sea surface temperatures (∼22-23°C) is typically associated with upwelling-driven enhancement of surface nutrient concentrations and primary production. Based on a detailed investigation of the distribution and sea-to-air fluxes of N2O in the eastern equatorial Atlantic (EEA), we show that the onset and seasonal development of the ACT can be clearly observed in surface N2O concentrations, which increase progressively as the cooling in the equatorial region proceeds during spring-summer. We observed a strong influence of the surface currents of the EEA on the N2O distribution, which allowed identifying “high” and “low” concentration regimes that were, in turn, spatially delimited by the extent of the warm eastward-flowing North Equatorial Countercurrent and the cold westward-flowing South Equatorial Current. Estimated sea-to-air fluxes of N2O from the ACT (mean 5.18±2.59 µmol m−2 d−1) suggests that in May-July 2011 this cold-water band doubled the N2O efflux to the atmosphere with respect to the adjacent regions, highlighting its relevance for marine tropical emissions of N2O. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-11T17:02:57.869086-05:
DOI: 10.1002/2016JC012238

• Assessing recent air-sea freshwater flux changes using a surface
temperature-salinity space framework
• Authors: Jeremy P. Grist; Simon A. Josey, Jan D. Zika, Dafydd Gwyn Evans, Nikolaos Skliris
PubDate: 2016-11-11T17:01:55.921755-05:
DOI: 10.1002/2016JC012091

• Barrier island breach evolution: Alongshore transport and bay-ocean
• Authors: Ilgar Safak; John C. Warner, Jeffrey H. List
PubDate: 2016-11-11T17:01:17.6961-05:00
DOI: 10.1002/2016JC012029

• Subduction of North Pacific Tropical Water and Its equatorward pathways as
shown by a simulated passive tracer
• Authors: Xunwei Nie; Shan Gao, Fan Wang, Tangdong Qu
PubDate: 2016-11-11T17:00:57.829169-05:
DOI: 10.1002/2016JC012305

• Radar imaging of shallow water bathymetry: A case study in the Yangtze
Estuary
• Authors: Peng Yu; Johnny A. Johannessen, Vladimir Kudryavtsev, Xiaojing Zhong, Yunxuan Zhou
PubDate: 2016-11-11T17:00:46.082791-05:
DOI: 10.1002/2016JC011973

• Carbon cycling dynamics in the seasonal sea-ice zone of East Antarctica
• Authors: Nicholas P. Roden; Bronte Tilbrook, Thomas W. Trull, Patti Virtue, Guy D. Williams
Abstract: The carbon cycle of the seasonally ice covered region of the southwest Indian Ocean sector of East Antarctica (30°-80°E, 60°-69°S) was investigated during austral summer (January – March 2006). Large variability in the drivers and timing of carbon cycling dynamics were observed and indicated that the study site was a weak net source of carbon dioxide (CO2) to the atmosphere of 0.8 ± 1.6 grams C m−2 during the ice-free period, with narrow bands of CO2 uptake observed near the continental margin and north of the Southern Antarctic Circumpolar Current Front. Continuous surface measurements of dissolved oxygen and the fugacity of CO2 were combined with net community production estimates from oxygen/argon ratios to show that surface heat gain and photosynthesis were responsible for the majority of observed surface water variability. On seasonal timescales, winter sea-ice cover reduced the flux of CO2 to the atmosphere in the study area, followed by biologically driven drawdown of CO2 as the ice retreated in spring-summer highlighting the important role that sea-ice formation and retreat has on the biogeochemical cycling of the region. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-11T17:00:41.888061-05:
DOI: 10.1002/2016JC012008

• Efficient boundary mixing due to near-inertial waves in a non-tidal basin:
Observations from the Baltic Sea
• Authors: C. Lappe; L. Umlauf
PubDate: 2016-11-11T17:00:38.033652-05:
DOI: 10.1002/2016JC011985

• Footprints of obliquely incident internal solitary waves and internal
tides near the shelf break in the northern South China Sea
• Authors: Xiaochuan Ma; Jun Yan, Yijun Hou, Feilong Lin, Xufeng Zheng
PubDate: 2016-11-11T17:00:24.762668-05:
DOI: 10.1002/2016JC012009

• Effects of ocean grid resolution on tropical cyclone-induced upper ocean
responses using a global ocean general circulation model
• Authors: Hui Li; Ryan L. Sriver
Abstract: Tropical cyclones (TCs) have the potential to influence regional and global climate through interactions with the upper ocean. Here we present results from a suite of ocean-only model experiments featuring the Community Earth System Model, in which we analyze the effect of tropical cyclone wind forcing on the global ocean using three different horizontal ocean grid resolutions (3˚, 1˚, and 0.1˚). The ocean simulations are forced with identical atmospheric inputs from the Coordinated Ocean-Ice Reference Experiments version 2 (COREv2) normal year forcing conditions, featuring global blended TC winds from a fully-coupled CESM simulation with a 25 km atmosphere [Small et al., 2014]. The simulated TC climatology shows good agreement with observational estimates of annual TC statistics, including annual frequency, intensity distributions, and geographic distributions. Each ocean simulation is comprised of a 5-year spin up with COREv2 normal year forcing, followed by 18 months with blended TC winds. In addition, we conduct corresponding control simulations for each grid resolution configuration without blended TC winds. We find that ocean horizontal and vertical grid resolutions affect TC-induced heat and momentum fluxes, post-storm cold wake features, and ocean subsurface temperature profiles. The responses are amplified for smaller grid spacing. Moreover, analyses show that the annually accumulated TC-induced ocean heat uptake is also sensitive to ocean grid resolution, which may have important implications for modeled ocean heat budgets and variability. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-07T09:19:03.335803-05:
DOI: 10.1002/2016JC011951

• Equatorial Pacific thermostad response to El Niño
• Authors: Gregory C. Johnson; Abigail N. Birnbaum
PubDate: 2016-11-07T09:18:26.783043-05:
DOI: 10.1002/2016JC012304

• Effects of an Arctic under-ice bloom on solar radiant heating of the water
column
• Authors: Torbjørn Taskjelle; Mats A. Granskog, Alexey K. Pavlov, Stephen R. Hudson, Børge Hamre
PubDate: 2016-11-07T09:18:00.909254-05:
DOI: 10.1002/2016JC012187

• Long-range propagation and associated variability of internal tides in the
South China Sea
• Authors: Zhenhua Xu; Kun Liu, Baoshu Yin, Zhongxiang Zhao, Yang Wang, Qun Li
Abstract: The variability of internal tides during their generation and long-range propagation in the South China Sea (SCS) is investigated by driving a high-resolution numerical model. The present study clarifies the notably different processes of generation, propagation and dissipation between diurnal and semidiurnal internal tides. Internal tides in the SCS originate from multiple source sites, among which the Luzon Strait is dominant, and contributes approximately 90% and 74% of the baroclinic energy for M2 and K1, respectively. To the west of the Luzon Strait, local generation of K1 internal tides inside the SCS is more energetic than the M2 tides. Diurnal and semidiurnal internal tides from the Luzon Strait radiate into the SCS in a north-south asymmetry but with different patterns because of the complex two-ridge system. The tidal beams can travel across the deep basin and finally arrive at the Vietnam coast and Nansha Island more than 1000-1500 km away. During propagation, M2 internal tides maintain a southwestward direction, whereas K1 exhibit complicated wave fields because of the superposition of waves from local sources and island scattering effects. After significant dissipation within the Luzon Strait, the remaining energy travels into the SCS and reduces by more than 90% over a distance of ∼1000 km. Inside the SCS, the K1 internal tides with long crests and flat beam angles are more influenced by seafloor topographical features and thus undergo apparent dissipation along the entire path, whereas the prominent dissipation of M2 internal tides only occurs after their arrival at Zhongsha Island. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-07T09:17:43.023495-05:
DOI: 10.1002/2016JC012105

• A modeling study of processes controlling the Bay of Bengal sea surface
salinity interannual variability
• Authors: V.P. Akhil; M. Lengaigne, J. Vialard, F. Durand, M. G. Keerthi, A.V.S. Chaitanya, F. Papa, V. V. Gopalakrishna, Clément de Boyer Montégut
PubDate: 2016-11-07T09:11:06.488671-05:
DOI: 10.1002/2016JC011662

• Direct estimates of friction factors for a mobile rippled bed
• Authors: S. Rodríguez-Abudo; D. L. Foster
Abstract: New friction factor estimates are computed from the total momentum transfer applied to a rippled sediment bed. The total time-dependent momentum flux is achieved by implementing the double-averaged horizontal momentum equation on the nearbed flow field collected with PIV. Time-independent friction factors are obtained by regressing the total momentum flux to the common quadratic stress law given by . The resulting friction factors compare favorably with available analysis techniques including energy dissipation, vertical turbulence intensity, and maximum shear stress, but can be 2-6 times smaller than estimates determined with the model by [1994] and the formula of Swart [1974] using the ripple roughness. This article is protected by copyright. All rights reserved.
PubDate: 2016-11-07T09:10:54.266417-05:
DOI: 10.1002/2016JC012055

• Isotope constraints on seasonal dynamics of dissolved and particulate N in
the Pearl River Estuary, South China
• Authors: Feng Ye; Guodong Jia, Luhua Xie, Gangjian Wei, Jie Xu
Abstract: Isotope measurements were performed on dissolved NO3−, NH4+ and suspended particulate total N along a salinity gradient in the Pearl River Estuary (PRE) to investigate seasonal changes in main N sources and its biogeochemical processing under the influence of monsoon climate. Our data revealed that municipal sewage and re-mineralized soil organic N were the major sources of DIN (NO3− and/or NH4+) in freshwater during winter and summer, respectively, whereas phytoplankton biomass was a major component of PN in both seasons. In low salinity waters (
PubDate: 2016-11-02T09:10:54.169304-05:
DOI: 10.1002/2016JC012066

• Long-range sediment transport in the world's oceans by stably stratified
turbidity currents
PubDate: 2016-10-27T03:40:35.040523-05:
DOI: 10.1002/2016JC011978

• A validated tropical-extratropical flood hazard assessment for New York
Harbor
• Authors: P.M. Orton; T.M. Hall, S.A. Talke, A.F. Blumberg, N. Georgas, S. Vinogradov
Abstract: Recent studies of flood risk at New York Harbor (NYH) have shown disparate results for the 100-year storm tide, providing an uncertain foundation for the flood mitigation response after Hurricane Sandy. Here, we present a flood hazard assessment that improves confidence in our understanding of the region's present-day potential for flooding, by separately including the contribution of tropical cyclones (TCs) and extratropical cyclones (ETCs), and validating our modeling study at multiple stages against historical observations. The TC assessment is based on a climatology of 606 synthetic storms developed from a statistical-stochastic model of North Atlantic TCs. The ETC assessment is based on simulations of historical storms with many random tide scenarios. Synthetic TC landfall rates and the final TC and ETC flood exceedance curves are all shown to be consistent with curves computed using historical data, within 95% confidence ranges. Combining the ETC and TC results together, the 100-year return period storm tide at NYH is 2.70 m (2.51-2.92 at 95% confidence), and Hurricane Sandy's storm tide of 3.38 m was a 260-year (170-420) storm tide. Deeper analyses of historical flood reports from estimated Category-3 hurricanes in 1788 and 1821 lead to new estimates and reduced uncertainties for their floods, and show that Sandy's storm tide was the largest at NYH back to at least 1700. The flood exceedance curves for ETCs and TCs have sharply different slopes due to their differing meteorology and frequency, warranting separate treatment in hazard assessments. This article is protected by copyright. All rights reserved.
PubDate: 2016-10-25T08:05:34.956258-05:
DOI: 10.1002/2016JC011679

• Circulation and oxygen cycling in the Mediterranean Sea: Sensitivity to
future climate change
• Authors: Helen Powley; Michael Krom, Philippe Van Cappellen
PubDate: 2016-10-25T08:05:33.37871-05:0
DOI: 10.1002/2016JC012224

• Nonlinear multiscale interactions and internal dynamics underlying a
typical eddy-shedding event at Luzon Strait
• Authors: Yuan-Bing Zhao; X. San Liang, Jianping Gan
PubDate: 2016-10-25T08:05:28.945498-05:
DOI: 10.1002/2016JC012483

• A system to measure the data quality of spectral remote sensing
reflectance of aquatic environments
• Authors: Jianwei Wei; Zhongping Lee, Shaoling Shang
Abstract: Spectral remote sensing reflectance (Rrs, sr−1) is the key for ocean color retrieval of water bio-optical properties. Since Rrs from in-situ and satellite systems are subject to errors or artifacts, assessment of the quality of Rrs data is critical. From a large collection of high quality in situ hyperspectral Rrs datasets, we developed a novel quality assurance (QA) system that can be used to objectively evaluate the quality of an individual Rrs spectrum. This QA scheme consists of a unique Rrs spectral reference and a score metric. The reference system includes Rrs spectra of 23 optical water types ranging from purple blue to yellow waters, with an upper and a lower bound defined for each water type. The scoring system is to compare any target Rrs spectrum with the reference and a score between 0 and 1 will be assigned to the target spectrum, with 1 for perfect Rrs spectrum and 0 for unusable Rrs spectrum. The effectiveness of this QA system is evaluated with both synthetic and in situ Rrs spectra and it is found to be robust. Further testing is performed with the NOMAD dataset as well as with satellite Rrs over coastal and oceanic waters, where questionable or likely erroneous Rrs spectra are shown to be well identifiable with this QA system. Our results suggest that applications of this QA system to in situ datasets can improve the development and validation of bio-optical algorithms and its application to ocean color satellite data can improve the short- and long-term products by objectively excluding questionable Rrs data. This article is protected by copyright. All rights reserved.
PubDate: 2016-10-25T08:05:23.160646-05:
DOI: 10.1002/2016JC012126

• Intraseasonal sea level variability along the West Coast of India
• Authors: Laxmikant Dhage; P. Ted Strub
Abstract: The importance of local versus distant forcing is studied for the wind driven intra-seasonal (30-120 day) sea level anomaly (SLA) variations along the west coast of India. Significant correlations of altimeter derived SLA on the west coast are found with the mid-basin SLA east of Sri-Lanka and SLA as far as Sumatra and the Equator, with increased lags, connecting with the remote forcing from the Equator in the form of reflected Rossby waves. The highest correlations between SLA on the west coast and winds are found with the winds at the southern tip of India. Coherence calculations help to identify the importance of a narrow band (40-60 day) for the interactions of winds with the intra-seasonal SLA variations. A multivariate regression model, along with the coherences within this narrower band, suggest the lags of SLA on the west coast with winds to range from 0-2 days with the local forcing to 11-13 days with the forcing along south east coast of India. Hovmöller diagrams illustrate the propagation of signals by estimating phase speed for Rossby waves (57 cm/s) across the Indian Ocean from Sumatra and Coastal trapped Waves (CTWs) along the west coast of India (178 cm/s). Propagation from the south-east coast of India is not as robust as Rossby waves from Sumatra. This article is protected by copyright. All rights reserved.
PubDate: 2016-10-20T21:00:27.430364-05:
DOI: 10.1002/2016JC011904

• Coherent motions and time scales that control heat and mass transfer at
wind-swept water surfaces
• Authors: D. E. Turney
PubDate: 2016-10-19T10:26:45.800745-05:
DOI: 10.1002/2016JC012139

• Seasonal patterns of SST diurnal variation over the Tropical Warm Pool
region
• Authors: Haifeng Zhang; Helen Beggs, Xiao Hua Wang, Andrew E. Kiss, Christopher Griffin
PubDate: 2016-10-19T10:26:34.038591-05:
DOI: 10.1002/2016JC012210

• Structure and dynamics of a subglacial discharge plume in a Greenlandic
Fjord
• Authors: Kenneth D. Mankoff; Fiammetta Straneo, Claudia Cenedese, Sarah B. Das, Clark G. Richards, Hanumant Singh
Abstract: Discharge of surface-derived meltwater at the submerged base of Greenland's marine-terminating glaciers creates subglacial discharge plumes that rise along the glacier/ocean interface. These plumes impact submarine melting, calving and fjord circulation. Observations of plume properties and dynamics are challenging due to their proximity to the calving edge of glaciers. Therefore to date information on these plumes has been largely derived from models. Here we present temperature, salinity, and velocity data collected in a plume that surfaced at the edge of Saqqarliup Sermia, a mid-sized Greenlandic glacier. The plume is associated with a narrow core of rising waters approximately 20 m in diameter at the ice edge that spreads to a 200 m by 300 m plume pool as it reaches the surface, before descending to its equilibrium depth. Volume flux estimates indicate that the plume is primarily driven by subglacial discharge and that this has been diluted in a ratio of 1:10 by the time the plume reaches the surface. While highly uncertain, meltwater fluxes are likely two orders of magnitude smaller than the subglacial discharge flux. The overall plume characteristics agree with those predicted by theoretical plume models for a convection driven plume with limited influence from submarine melting. This article is protected by copyright. All rights reserved.
PubDate: 2016-10-19T10:20:27.03883-05:0
DOI: 10.1002/2016JC011764

• Air pressure effects on sea level changes during the Twentieth Century
• Authors: Christopher G. Piecuch; Philip R. Thompson, Kathleen A. Donohue
Abstract: Interpretation of tide gauge data in terms sea level (η) and ocean dynamics requires estimates of air pressure (pa) to determine the ocean's isostatic response—the inverted barometer effect (ηib). Three gridded pa products (HadSLP2, NOAA-20CRv2, ERA-20C) are used alongside meteorological station pa and tide gauge η records to evaluate the contribution of ηib to η changes over the Twentieth Century. Agreement between gridded products is better during more recent periods and over regions with good historical data coverage, whereas it is worse for earlier time periods or in ocean areas with poor observational data coverage. Comparison against station data reveals the presence of systematic errors in the gridded products, for example, such that uncertainties estimated through differencing the gridded products underestimate the true errors by roughly $40\%$on interannual and decadal time scales. Notwithstanding such correlated errors, gridded products are still {useful} for interpretation of tide gauge data. Removing gridded estimates of ηib from η records reduces spatial variance in centennial trends across tide gauges by 10–30%, formal errors in centennial trends from individual gauges by ∼ 5%, and the temporal variance in detrended records by 10–15% on average (depending on choice of gridded product). Results here advocate for making the ηib correction to tide gauge records in studies of ocean circulation and global η over long, multidecadal and centennial time scales using an ensemble mean taken across several gridded ηib products. This article is protected by copyright. All rights reserved.
PubDate: 2016-10-18T02:50:53.148746-05:
DOI: 10.1002/2016JC012131

• Mapping error in Southern Ocean transport computed from satellite
altimetry and Argo
• Authors: Michael Kosempa; Don P. Chambers
Abstract: In an effort to better estimate transport dynamics in response to wind forcing (primarily the Southern Annual Mode), this study quantifies the uncertainty in mapping zonal geostrophic transport of the Antarctic Circumpolar Current from sparse temperature, salinity and sea surface height observations. To do this, we sampled an ocean state estimate at the locations of both Argo floats and the Jason-1 altimeter groundtrack. These sampled values were then optimally interpolated to create SSH and temperature/salinity grids with 1° resolution. The temperature, salinity and SSH grids were then combined to compute the zonal geostrophic transport and compared to that estimated from the full state estimate. There are significant correlations between the baroclinic and barotropic error contributions to the total transport error. The increase in Argo floats in the Southern Ocean is effective in reducing mapping error. However, that error improvement is not uniform. By analyzing systematic errors in transport time series, we find the transects that are most appropriate for analyzing the dynamics of ACC transport using Argo and altimetric gridded fields. Based on our analysis, we conclude region south of Tasmania is most appropriate, with lowest uncertainty. Using real-world data, we calculated zonal transport variability at a transect south of Tasmania. There is an insignificant trend (0.3 ± 0.4 Sv yr−1, 90% confidence) but significant low-frequency variability correlated with the Southern Annular Mode (0.53, p
PubDate: 2016-10-18T02:50:46.211771-05:
DOI: 10.1002/2016JC011956

• Projecting nuisance flooding in a warming climate using generalized linear
models and Gaussian processes
• Authors: Alexander Vandenberg-Rodes; Hamed R. Moftakhari, Amir AghaKouchak, Babak Shahbaba, Brett F. Sanders, Richard A. Matthew
Abstract: Nuisance flooding corresponds to minor and frequent flood events that have significant socio-economic and public health impacts on coastal communities. Yearly-averaged local mean sea level can be used as proxy to statistically predict the impacts of sea level rise (SLR) on the frequency of nuisance floods (NF). In this study, we use Generalized Linear Models (GLM) and Gaussian Process (GP) models combined to (i) estimate the frequency of NF associated with the change in mean sea level, and (ii) quantify the associated uncertainties via a novel and statistically robust approach. We calibrate our models to the water level data from eighteen tide gauges along the coasts of United States, and after validation, we estimate the frequency of NF associated with the SLR projections in year 2030 (under RCPs 2.6 and 8.5), along with their 90% bands, at each gauge. The historical NF-SLR data is very noisy, and shows large changes in variability (heteroscedasticity) with SLR. Prior models in the literature do not properly account for the observed heteroscedasticity, and thus their projected uncertainties are highly suspect. Among the models used in this study the Negative Binomial Distribution GLM with GP best characterizes the uncertainties associated with NF estimates; on validation data ≈ 93% of the points fall within the 90% credible limit, showing our approach to be a robust model for uncertainty quantification. This article is protected by copyright. All rights reserved.
PubDate: 2016-10-18T02:50:23.747946-05:
DOI: 10.1002/2016JC012084

• Processes of multibathyal aragonite undersaturation in the Arctic Ocean
• Authors: J.G. Wynn; L.L. Robbins, L.G. Anderson
Abstract: During three years of study (2010-2012), the western Arctic Ocean was found to have unique aragonite saturation profiles with up to three distinct aragonite undersaturation zones. This complexity is produced as inflow of Atlantic- and Pacific-derived water masses mix with Arctic-derived waters, which are further modified by physiochemical and biological processes. The shallowest aragonite undersaturation zone, from the surface to ∼ 30 m depth is characterized by relatively low alkalinity and other dissolved ions. Besides local influence of biological processes on aragonite undersaturation of shallow coastal waters, the nature of this zone is consistent with dilution by sea-ice melt and invasion of anthropogenic CO2 from the atmosphere. A second undersaturated zone at ∼ 90-220 m depth (salinity ∼31.8–35.4) occurs within the Arctic Halocline and is characterized by elevated pCO2 and nutrients. The nature of this horizon is consistent with remineralization of organic matter on shallow continental shelves bordering the Canada Basin and the input of the nutrients and CO2 entrained by currents from the Pacific Inlet. Finally, the deepest aragonite undersaturation zone is at greater than 2000 m depth and is controlled by similar processes as deep aragonite saturation horizons in the Atlantic and Pacific Oceans. The comparatively shallow depth of this deepest aragonite saturation horizon in the Arctic is maintained by relatively low temperatures, and stable chemical composition. Understanding the mechanisms controlling the distribution of these aragonite undersaturation zones, and the timescales over which they operate will be crucial to refine predictive models. This article is protected by copyright. All rights reserved.
PubDate: 2016-10-13T03:46:18.997671-05:
DOI: 10.1002/2016JC011696

• Gulf Stream variability and a triggering mechanism of its large meander in
the South Atlantic Bight
• Authors: Xiangming Zeng; Ruoying He
PubDate: 2016-10-13T03:46:11.526959-05:
DOI: 10.1002/2016JC012077

• Impact of an upgraded model in the NCEP Global Ocean Data Assimilation
System: The tropical Indian Ocean
• Authors: Hasibur Rahaman; David Behringer, Stephen G. Penny, M Ravichandran
PubDate: 2016-10-13T03:45:59.559059-05:
DOI: 10.1002/2016JC012056

• Observations of open-ocean deep convection in the northwestern
Mediterranean Sea: Seasonal and interannual variability of mixing and deep
water masses for the 2007–2013 period
• Authors: L. Houpert; X. Durrieu de Madron, P. Testor, A. Bosse, F. D'Ortenzio, M.N. Bouin, D. Dausse, H. Le Goff, S. Kunesch, M. Labaste, L. Coppola, L. Mortier, P. Raimbault
Abstract: We present here a unique oceanographic and meteorological dataset focus on the deep convection processes. Our results are essentially based on in situ data (mooring, research vessel, glider, and profiling float) collected from a multi-platform and integrated monitoring system (MOOSE: Mediterranean Ocean Observing System on Environment), which monitored continuously the northwestern Mediterranean Sea since 2007, and in particular high-frequency potential temperature, salinity and current measurements from the mooring LION located within the convection region.From 2009 to 2013, the mixed layer depth reaches the seabed, at a depth of 2330m, in February. Then, the violent vertical mixing of the whole water column lasts between 9 and 12 days setting up the characteristics of the newly-formed deep water. Each deep convection winter formed a new warmer and saltier '“vintage” of deep water. These sudden inputs of salt and heat in the deep ocean are responsible for trends in salinity (3.3+/-0.2 *10−3/yr) and potential temperature (3.2+/-0.5 *10−3°C/yr) observed from 2009 to 2013 for the 600-2300m layer.For the first time, the overlapping of the 3 “phases” of deep convection can be observed with secondary vertical mixing events (2-4 days) after the beginning of the restratification phase, and the restratification/spreading phase still active at the beginning of the following deep convection event. This article is protected by copyright. All rights reserved.
PubDate: 2016-10-13T03:43:19.995887-05:
DOI: 10.1002/2016JC011857

• Dissipation of wind waves by pancake and frazil ice in the autumn Beaufort
Sea
• Authors: W. Erick Rogers; Jim Thomson, Hayley H. Shen, Martin J. Doble, Peter Wadhams, Sukun Cheng
Abstract: A model for wind-generated surface gravity waves, WAVEWATCH III®, is used to analyze and interpret buoy measurements of wave spectra. The model is applied to a hindcast of a wave event in sea ice in the western Arctic, October 11-14 2015, for which extensive buoy and ship-borne measurements were made during a research cruise. The model, which uses a viscoelastic parameterization to represent the impact of sea ice on the waves, is found to have good skill—after calibration of the effective viscosity—for prediction of total energy, but over-predicts dissipation of high frequency energy by the sea ice. This shortcoming motivates detailed analysis of the apparent dissipation rate. A new inversion method is applied to yield, for each buoy spectrum, the inferred dissipation rate as a function of wave frequency. For 102 of the measured wave spectra, visual observations of the sea ice were available from buoy-mounted cameras, and ice categories (primarily for varying forms of pancake and frazil ice) are assigned to each based on the photographs. When comparing the inversion-derived dissipation profiles against the independently derived ice categories, there is remarkable correspondence, with clear sorting of dissipation profiles into groups of similar ice type. These profiles are largely monotonic: they do not exhibit the “roll-over” that has been found at high frequencies in some previous observational studies. This article is protected by copyright. All rights reserved.
PubDate: 2016-10-13T03:35:53.941718-05:
DOI: 10.1002/2016JC012251

• Chromophoric and fluorescent dissolved organic matter in and above the
oxygen minimum zone off Peru
• Authors: A.N. Loginova; S. Thomsen, A. Engel
PubDate: 2016-10-13T03:30:53.767001-05:
DOI: 10.1002/2016JC011906

• Decomposition of thermal and dynamic changes in the South China Sea
induced by boundary forcing and surface fluxes during 1970‒2000
• Authors: Jun Wei; Paola Malanotte-Rizzoli, Ming-Ting Li, Hao Wang
PubDate: 2016-10-07T10:30:51.901249-05:
DOI: 10.1002/2016JC012078

• Interannual and interdecadal variability of the North Equatorial
Countercurrent in the Western Pacific
• Authors: Xiao Chen; Bo Qiu, Yan Du, Shuiming Chen, Yiquan Qi
PubDate: 2016-10-06T10:15:26.106931-05:
DOI: 10.1002/2016JC012190

• Long-term decrease in phosphate concentrations in the surface layer of the
southern Japan Sea
• Authors: Taketoshi Kodama; Yosuke Igeta, Mizuki Kuga, Shoko Abe
PubDate: 2016-10-05T10:26:00.060089-05:
DOI: 10.1002/2016JC012168

• Winter ocean-ice interactions under thin sea ice observed by IAOOS
platforms during N-ICE2015: Salty surface mixed layer and active basal
melt
• Authors: Zoé Koenig; Christine Provost, Nicolas Villacieros-Robineau, Nathalie Sennéchael, Amélie Meyer
PubDate: 2016-10-05T10:25:57.729296-05:
DOI: 10.1002/2016JC012195

• Time series measurements of transient tracers and tracer derived transport
in the deep western boundary current between the Labrador Sea and the
subtropical Atlantic Ocean at Line W
• Authors: John N. Smith; William M. Smethie, Igor Yashayev, Ruth Curry, Kumiko Azetsu-Scott
PubDate: 2016-10-05T10:25:55.624726-05:
DOI: 10.1002/2016JC011759

• CMIP5 earth system models with biogeochemistry: An assessment for the
southwest Pacific Ocean
• Authors: Graham J. Rickard; Erik Behrens, Stephen M. Chiswell
Abstract: An assessment is made of the ability of CMIP5 models to represent the seasonal biogeochemical cycles over the late twentieth century in the southwest Pacific Ocean. In particular, sea surface temperature (SST), surface chlorophyll a, nitrate, phosphate, silicate, and the depth of the seasonal thermocline, are examined to quantify the physical-biogeochemical capabilities of each model; the result is a “ranking” estimate enabling model ensemble generation. The better/less ranked ensembles we refer to as inner/outer, respectively. The ensembles then allow less well observed variables such as iron and vertically integrated primary production to be assessed. The assessment establishes model output confidence limits for setting bounds on future model scenario ecosystem change projections. By the end of the twenty first century under Representative Concentration Pathways (RCP) RCP4.5 and/or RCP8.5 our best estimates suggest that there will be average domain wide increases in SST and surface iron, but average decreases in surface chlorophyll a, nitrate, and phosphate, accompanied by relatively large decreases in the depth of the seasonal thermocline (all changes realised by both ensembles). On the other hand, for surface silicate the inner ensemble suggests general declines, and vice versa for the outer ensemble. For integrated primary production the ensembles predict declines in subtropical water, but elsewhere generally less significant changes. This article is protected by copyright. All rights reserved.
PubDate: 2016-10-05T10:25:53.513578-05:
DOI: 10.1002/2016JC011736

• Observations and Modeling of a Tidal Inlet Dye Tracer Plume
• Authors: Falk Feddersen; Maitane Olabarrieta, R. T. Guza, D. Winters, Britt Raubenheimer, Steve Elgar
Abstract: A 9 km-long tracer plume was created by continuously releasing Rhodamine WT dye for 2.2 h during ebb tide within the southern edge of the main tidal channel at New River Inlet, NC on May 7, 2012, with highly obliquely incident waves and alongshore winds. Over 6 h from release, COAWST (coupled ROMS and SWAN, including wave, wind, and tidal forcing) modeled dye compares well with (aerial hyperspectral and in situ) observed dye concentration. Dye first was transported rapidly seaward along the main channel and partially advected across the ebb-tidal shoal until reaching the offshore edge of the shoal. Dye did not eject offshore in an ebb-tidal jet because the obliquely incident breaking waves retarded the inlet-mouth ebb-tidal flow and forced currents along the ebb shoal. The dye plume largely was confined to
PubDate: 2016-10-04T10:25:55.161221-05:
DOI: 10.1002/2016JC011922

• The Beaufort Gyre intensification and stabilization: A model-observation
synthesis
• Authors: Jinlun Zhang; Michael Steele, Kay Runciman, Sarah Dewey, James Morison, Craig Lee, Luc Rainville, Sylvia Cole, Richard Krishfield, Mary-Louise Timmermans, John Toole
Abstract: A model–observation synthesis is conducted to investigate changes in the upper ocean circulation and stratification in the Canada Basin (CB) of the Arctic Ocean. Results show that the Beaufort Gyre (BG) has been generally intensifying during 1992–2015 in conjunction with changes in sea ice and the upper ocean including increasing sea surface height (SSH), sea ice and ocean speed, Ekman transport convergence and downwelling, and freshwater content, decreasing ice thickness and upper ocean salinity, shoaling summer halocline and mixed layer, and deepening winter halocline and mixed layer. Increasing Ekman transport convergence draws more water from surrounding areas into the CB, thus lowering SSH in those areas and raising SSH in the CB. The rate of change in the CB began to decrease in 2008 and the BG circulation appears to be stabilizing, if not relaxing slightly. This is reflected in the general plateauing of SSH, the intensity of the sea ice and ocean circulation, and various measures of the CB thermohaline stratification. The BG intensification and subsequent stabilization appear to have been strongly controlled by atmospheric changes in the CB characterized by generally increasing anticyclonic wind circulation and sea level pressure (SLP) before 2008 and falling wind strength and SLP to below-average levels in some years after 2008. Changes in SLP are highly correlated with changes in ocean surface stress curl and downwelling. Since 2008, the magnitude of the stress curl and downwelling in much of the CB has declined, contributing to BG stabilization. The general leveling-off of sea ice thickness also contributes to the stabilization by limiting melt water input to the CB that increases freshwater content. Temperatures in the Near Surface Temperature Maximum layer trended upward slightly over 1992–2015, which is closely correlated with decreasing sea ice thickness. Upper ocean heat content increased over the study period mainly due to strong temperature increases in the summer Pacific Water layer. This article is protected by copyright. All rights reserved.
PubDate: 2016-10-04T10:25:53.440564-05:
DOI: 10.1002/2016JC012196

• Impact of model resolution for on-shelf heat transport along the West
Antarctic Peninsula
• Authors: Jennifer A Graham; Michael S Dinniman, John M Klinck
PubDate: 2016-10-04T10:20:53.977797-05:
DOI: 10.1002/2016JC011875

Variability
• Authors: Igor Yashayaev; John W. Loder
PubDate: 2016-09-30T03:45:42.867176-05:
DOI: 10.1002/2016JC012046

• Tidal distortion caused by the resonance of sexta-diurnal tides in a
micro-mesotidal embayment
• Authors: Dehai Song; Yuhan Yan, Wen Wu, Xiliang Diao, Yang Ding, Xianwen Bao
PubDate: 2016-09-30T03:40:43.680092-05:
DOI: 10.1002/2016JC012039

• Century-scale perspectives on observed and simulated Southern Ocean sea
ice trends from proxy reconstructions
• Authors: Will Hobbs; Mark Curran, Nerilie Abram, Elizabeth R. Thomas
Abstract: Observations show that Southern Ocean sea ice extent has increased since 1979, whereas global coupled climate models simulate a decrease over the same period. It is uncertain whether the observed trends are anthropogenically forced or due to internal variability, and whether the discrepancy between models and observations is also due to internal variability or indicative of a significant deficiency in the models. The length of the passive microwave satellite record hampers research into this question, which is too short to resolve multidecadal variability. Here, we use a number of proxies for regional seasonal sea ice extent around the Antarctic region to reconstruct sea ice extent for the full 20th century, which we compare with CMIP5 model simulations. We find that for the East Antarctic, Amundsen and Bellingshausen Seas, models and reconstructions agree that there has been a decrease in sea ice extent since the early 1970s, but this decrease is small compared to the simulated internal variability of the system. The Ross Sea is a confounding factor, with a significant increase in sea ice since 1979 that is not captured by climate models; however, existing proxy reconstructions of this region are not yet sufficiently reliable for formal change detection. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-30T03:36:08.469928-05:
DOI: 10.1002/2016JC012111

• Laboratory simulation of the geothermal heating effects on ocean
overturning circulation
• Authors: Fei Wang; Shi-Di Huang, Sheng-Qi Zhou, Ke-Qing Xia
Abstract: Motivated by a desire to understand the geothermal heating effects on ocean circulation, a large-scale circulation generated and sustained by thermal forcing at the surface subject to a small amount of heating from the bottom boundary is investigated through laboratory experiments, motivated by understanding the geothermal heating effects on ocean circulation. Despite its idealization, our experiments demonstrate that the leading order effect of geothermal heating is to significantly enhance the abyssal overturning, in agreement with the findings in ocean circulation models. Our experiments also demonstrate that geothermal heating cannot influence the poleward heat transport due to the strong stratification in the thermocline. Our study further reveals that the ratio of geothermal-flux-induced turbulent dissipation to the dissipation due to other energies is the key parameter determining the dynamical importance of geothermal heating. This quantity explains why the impact of geothermal heating is sensitive to the deep stratification, the diapycnal mixing and the amount of geothermal flux. Moreover, it is found that this dissipation ratio may be used to understand results from different studies in a consistent way. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-30T03:36:06.617896-05:
DOI: 10.1002/2016JC012068

• Effects of mesoscale eddies on the volume transport and branch pattern of
the Kuroshio east of Taiwan
• Authors: Xiaomei Yan; Xiao‐Hua Zhu, Chongguang Pang, Linlin Zhang
Abstract: Using satellite altimeter data and a long‐term altimetric transport index for the Kuroshio inflow northeast of Taiwan, the effects of mesoscale eddies on the Kuroshio volume transport (KVT) at the East Taiwan Channel and the branching pattern of the Kuroshio east of Taiwan are investigated at scales from those of individual events to interannual timescales. Both anticyclonic and cyclonic eddies are found to be able either to strengthen or weaken the KVT, depending on the relative strength of mass convergence and divergence produced upstream and downstream of the eddies. The major factor influencing the intensity of the Kuroshio inflow is the meridional location of the eddies. For single eddy events, the KVT is significantly correlated with the latitude of the eddy's center, the correlations being 0.44 and ‐0.48 for anticyclonic and cyclonic eddies, respectively. For dipole eddy events, when the direction angle falls in the interval 40°‐150° (240°‐300°), the KVT anomaly tends to be positive (negative). Furthermore, low KVT events generally correspond to the formation of the Ryukyu Current branch, which is also generated from strong mass divergence produced by the eddies. In addition, on interannual time scales, the variation of KVT is closely related to the relative number of anticyclonic to cyclonic eddies west of 125°E, with a correlation of 0.5. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-28T03:32:07.999989-05:
DOI: 10.1002/2016JC012038

• Weakest winter South China Sea western boundary current caused by the
2015–2016 El Niño event
• Authors: Ruixiang Zhao; Xiao‐Hua Zhu
Abstract: During the winter of 2015–2016, the strongest El Niño event of the 21st century occurred. At the same time, volume transport (VT) time series of the South China Sea western boundary current (SCSWBC) exhibited a minimum value of 3.7 Sv (1 Sv = 1 × 106 m3 s−1) toward the southwest, indicating the weakest strength ever recorded in boreal winter (from November to February). The South China Sea (SCS) cyclonic gyre, inferred from the satellite‐derived surface absolute geostrophic current, was significantly reduced. It was considered that the weakened wind stress curl (negative anomaly) over the SCS resulting from an anticyclone over the Philippine Sea played an essential role. The anticyclone arose from a Rossby‐wave response to a negative sea surface temperature anomaly in the northwest Pacific. This idea is further supported by composite analysis, which shows that during El Niño (La Niña) winter, negative (positive) wind stress curl anomalies prevail in the Philippines Sea and the SCS; thus, the wind stress curl over the SCS is reduced (strengthened), leading to a weaker (stronger) SCS cyclonic gyre and SCSWBC. The mean VT of SCSWBC is 4.7 Sv (5.6 Sv), which is smaller (larger) than 5.2 Sv in normal years. This study provides robust observational evidence from long‐term in situ volume transport monitoring that El Niño can have a significant impact on the SCSWBC through an atmosphere‐bridged teleconnection. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-28T03:31:49.945392-05:
DOI: 10.1002/2016JC012252

• Pressure field induced in the water column by acoustic‐gravity waves
generated from sea bottom motion
• Authors: Tiago C. A. Oliveira; Usama Kadri
Abstract: An uplift of the ocean bottom caused by a submarine earthquake can trigger acoustic‐gravity waves that travel at near the speed of sound in water and thus may act as early tsunami precursors. We study the spatio‐temporal evolution of the pressure field induced by acoustic‐gravity modes during submarine earthquakes, analytically. We show that these modes may all induce comparable temporal variations in pressure at different water depths in regions far from the epicenter, though the pressure field depends on the presence of a leading acoustic‐gravity wave mode. Practically, this can assist in the implementation of an early tsunami detection system by identifying the pressure and frequency ranges of measurement equipment and appropriate installation locations. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-28T03:27:02.815803-05:
DOI: 10.1002/2016JC011742

• Vernal distribution and turnover of dimethylsulfide (DMS) in the surface
water of the Yellow Sea
• Authors: Cheng‐Xuan Li; Gui‐Peng Yang, Bao‐Dong Wang, Zong‐Jun Xu
Abstract: The spatial and interannual variations of dimethylsulfide (DMS) and its precursors, dissolved and particulate dimethylsulfoniopropionate (DMSP), were discussed on the basis of field observations in the surface waters of the Yellow Sea during spring 2007. Maxima of dimethylated sulfur compounds and low chlorophyll a concentrations were found in the central southern Yellow Sea, whereas low concentrations of DMS and DMSP were detected at the boundary between the northern and southern parts of the Yellow Sea. This frontal region is influenced by active water currents, air–sea interface exchanges, and biological turnover. The horizontal variations in DMS production and consumption rates showed a decreasing tendency from the coastal to offshore areas mainly due to the complicated biological features. DMS positively correlated with dissolved CH4 and CO2 but negatively correlated with nutrients (nitrite and phosphate). Particulate DMSP concentrations and DMS production rates positively correlated with dinoflagellate abundances but negatively correlated with diatom cell densities. DMS and DMSP concentrations, as well as DMS production and consumption rates, exhibited approximately 2.0‐2.8 fold increases from 2005 to 2012. This finding was likely caused by shifts in the phytoplankton communities from diatoms to dinoflagellates and the increases in abundances of zooplankton and bacteria. Average sea‐to‐air DMS fluxes were estimated to be 8.12 ± 1.24 µmol·(m−2·d−1), and DMS microbial consumption was approximately 1.68 times faster than the DMS sea–air exchange. These findings imply that biological consumption, relative to ventilation, is a predominant mechanism in DMS removal from the surface water. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-28T03:21:26.848701-05:
DOI: 10.1002/2016JC011901

• Assessing controls on cross‐shelf phytoplankton and suspended particle
distributions using repeated bio‐optical glider surveys
• Authors: Fernanda Henderikx Freitas; David A. Siegel, Libe Washburn, Stuart Halewood, Erik Stassinos
Abstract: Characterizing the space/time variability of bio‐optical properties is essential to understanding the mechanisms that control cross‐shelf phytoplankton and suspended particle distributions in coastal waters. Approximately 400 high‐resolution cross‐shelf sections of bio‐optical properties collected with an oceanographic glider in the coastal Santa Barbara Channel, California, revealed complex relationships among optical properties and environmental conditions. Surface waves were found as a proximate control on suspended sediment variability for both inner and mid‐shelves. Increases in phytoplankton abundances attributed to horizontal advection and upwelling events were observed only on episodic time scales. The lack of all‐encompassing linear relationships between environmental forcings and changes in cross‐shelf phytoplankton highlight the challenge of decoupling bio‐optical signals from their controlling processes in coastal zones where phytoplankton distributions are patchy, and where nearshore and offshore phytoplankton populations and suspended sediments often occupy the same portion of the water column. Clear relationships between runoff and productivity were not observed. Temporal variability of suspended particles and phytoplankton distributions were roughly independent from each other during stratified conditions. Synchronous increases in phytoplankton and suspended sediments were observed when associated with strong upwelling events that may induce mixing and promote productivity. The repeated glider sections illustrated many processes regulating phytoplankton and particle transport in the innershelf and showed the difficulty in establishing general connections between high‐frequency changes in optical properties and potential environmental forcings in a complex coastal environment. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-26T18:15:30.835054-05:
DOI: 10.1002/2016JC011781

• Scales and dynamics of submesoscale coherent vortices formed by deep
convection in the northwestern Mediterranean Sea
• Authors: Anthony Bosse; Pierre Testor, Loïc Houpert, Pierre Damien, Louis Prieur, Daniel Hayes, Vincent Taillandier, Xavier Durrieu de Madron, Fabrizio d'Ortenzio, Laurent Coppola, Johannes Karstensen, Laurent Mortier
PubDate: 2016-09-26T02:57:39.972444-05:
DOI: 10.1002/2016JC012144

• Laboratory experiments on diffusive convection layer thickness and its
oceanographic implications
• Authors: Shuang‐Xi Guo; Sheng‐Qi Zhou, Ling Qu, Yuan‐Zheng Lu
Abstract: We studied the thickness of diffusive convective layers that form when a linearly stratified fluid is subjected to heating from below in the laboratory. The thickness of the bottom convecting layer is much larger than subsequent layers. These thicknesses are systematically identified and used to examine the available convecting layer thickness parameterizations, which are consisted of the measured heat flux F (or thermal buoyancy flux qT), initial stratification N, density ratio Rρ, thermal diffusivity κT, etc. Parameterization with an intrinsic length scale (qT3κTN8)1/4 is shown to be superior. Including the present laboratory convecting layer thicknesses and those observed in oceans and lakes, where layer thickness ranges from 0.01 to 1000 m, the parameterization is updated as H=C(Rρ−1)2(qT3κTN8)1/4, where C=38.3 for the bottom convective layer and 10.8 for the subsequent layers. Different prefactors are proposed to be attributed to different convective instabilities induced by different boundary conditions. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-22T09:55:55.381865-05:
DOI: 10.1002/2016JC012172

• Teleconnection between the North Indian Ocean high swell events and
meteorological conditions over the Southern Indian Ocean
• Authors: P G Remya; S Vishnu, B Praveen Kumar, TM Balakrishnan Nair, B Rohith
PubDate: 2016-09-21T19:10:44.497883-05:
DOI: 10.1002/2016JC011723

• Measurement and modeling of oil slick transport
• Authors: Cathleen E. Jones; Knut‐Frode Dagestad, Øyvind Breivik, Benjamin Holt, Johannes Röhrs, Kai Håkon Christensen, Martine Espeseth, Camilla Brekke, Stine Skrunes
PubDate: 2016-09-21T18:35:26.123817-05:
DOI: 10.1002/2016JC012113

• Tsunami generation and associated waves in the water column and seabed due
to an asymmetric earthquake motion within an anisotropic substratum
• Authors: Amirhossein Bagheri; Stewart Greenhalgh, Ali Khojasteh, Mohammad Rahimian, Reza Attarnejad
PubDate: 2016-09-21T18:35:21.897982-05:
DOI: 10.1002/2016JC011944

• Enhanced turbulence driven by mesoscale motions and flow‐topography
interaction in the Denmark Strait Overflow plume
• Authors: Janin Schaffer; Torsten Kanzow, Kerstin Jochumsen, Klas Lackschewitz, Sandra Tippenhauer, Victor M. Zhurbas, Detlef Quadfasel
Abstract: The Denmark Strait Overflow (DSO) contributes roughly half to the total volume transport of the Nordic overflows. The overflow increases its volume by entraining ambient water as it descends into the subpolar North Atlantic, feeding into the deep branch of the Atlantic Meridional Overturning Circulation. In June 2012 a multi‐platform experiment was carried out in the DSO plume on the continental slope off Greenland (180 km downstream of the sill in Denmark Strait), to observe the variability associated with the entrainment of ambient waters into the DSO plume. In this study we report on two high‐dissipation events captured by an autonomous underwater vehicle (AUV) by horizontal profiling in the interfacial layer between the DSO plume and the ambient water. Strong dissipation of turbulent kinetic energy of O(10‐6) W kg‐1 was associated with enhanced small‐scale temperature variance at wavelengths between 0.05 and 500 m as deduced from a fast‐response thermistor. Isotherm displacement slope spectra reveal a wavenumber‐dependence characteristic of turbulence in the inertial‐convective subrange (k1/3) at wavelengths between 0.14 and 100 m. The first event captured by the AUV was transient, and occurred near the edge of a bottom‐intensified energetic eddy. Our observations imply that both horizontal advection of warm water and vertical mixing of it into the plume are eddy‐driven and go hand in hand in entraining ambient water into the DSO plume. The second event was found to be a stationary feature on the upstream side of a topographic elevation located in the plume pathway. Flow‐topography interaction is suggested to drive the intense mixing at this site. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-21T11:10:38.629141-05:
DOI: 10.1002/2016JC011653

• Wind‐driven export of Weddell Sea slope water
• Authors: A.J.S. Meijers; M.P. Meredith, E.P. Abrahamsen, M.A. Morales Maqueda, D.C. Jones, A.C. Naveira Garabato
Abstract: The export of waters from the Weddell Gyre to lower latitudes is an integral component of the southern subpolar contribution to the three‐dimensional oceanic circulation. Here, we use more than 20 years of repeat hydrographic data on the continental slope on the northern tip of the Antarctic Peninsula and five years of bottom lander data on the slope at 1000 m to show the intermittent presence of a relatively cold, fresh westward‐flowing current. This is often bottom intensified between 600‐2000 dbar with velocities of over 20 cms−1, transporting an average of 1.5±1.5 Sv. By comparison with hydrography on the continental slope within the Weddell Sea and modelled tracer release experiments we show that this slope current is an extension of the Antarctic Slope Current that has crossed the South Scotia Ridge west of Orkney Plateau. On monthly to interannual timescales the density of the slope current is negatively correlated (r >0.6 with a significance of over 95%) with eastward wind stress over the northern Weddell Sea, but lagging it by 6‐13 months. This relationship holds in both the high temporal resolution bottom lander time series and the 20+ year annual hydrographic occupations and agrees with Weddell Sea export variability observed further east. We compare several alternative hypotheses for this wind‐stress/export relationship and find that it is most consistent with wind‐driven acceleration of the gyre boundary current, possibly modulated by eddy dynamics, and represents a mechanism by which climatic perturbations can be rapidly transmitted as fluctuations in the supply of intermediate‐level waters to lower latitudes. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-21T11:00:30.892787-05:
DOI: 10.1002/2016JC011757

• Direct observations of the Antarctic Slope Current transport at 113°E
• Authors: B. Peña‐Molino; M. S. McCartney, S. R. Rintoul
PubDate: 2016-09-21T11:00:26.473997-05:
DOI: 10.1002/2015JC011594

• Wind relaxation and a coastal buoyant plume north of Pt. Conception, CA:
Observations, simulations, and scalings
• Authors: Sutara Suanda; Nirnimesh Kumar, Arthur J. Miller, Emanuele DiLorenzo, Kevin Haas, Donghua Cai, Christopher A. Edwards, Libe Washburn, Melanie Fewings, Rachel Torres, Falk Feddersen
Abstract: In upwelling regions, wind relaxations lead to poleward propagating warm water plumes that are important to coastal ecosystems. The coastal ocean response to wind relaxation around Pt. Conception, CA is simulated with a Regional Ocean Model (ROMS) forced by realistic surface and lateral boundary conditions including tidal processes. The model reproduces well the statistics of observed subtidal water column temperature and velocity at both outer‐ and inner‐shelf mooring locations throughout the study. A poleward‐propagating plume of Southern California Bight water that increases shelf water temperatures by ≈ 5°C is also reproduced. Modeled plume propagation speed, spatial scales, and flow structure are consistent with a theoretical scaling for coastal buoyant plumes with both surface‐trapped and slope‐controlled dynamics. Plume momentum balances are distinct between the offshore (> 30‐m depth) region where the plume is surface‐trapped, and onshore of the 30‐m isobath (within 5 km from shore) where the plume water mass extends to the bottom and is slope‐controlled. In the onshore region, bottom stress is important in the alongshore momentum equation and generates vertical vorticity that is an order of magnitude larger than the vorticity in the plume core. Numerical experiments without tidal forcing show that modeled surface temperatures are biased 0.5°C high, potentially affecting plume propagation distance and persistence. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-20T03:45:32.764738-05:
DOI: 10.1002/2016JC011919

• Variability, trends, and predictability of seasonal sea ice retreat and
• Authors: Mark C. Serreze; Alex D. Crawford, Julienne Stroeve, Andrew P. Barrett, Rebecca A. Woodgate
PubDate: 2016-09-19T18:35:35.422629-05:
DOI: 10.1002/2016JC011977

• Remote sources for year‐to‐year changes in the seasonality of the
Florida Current transport
• Authors: Ricardo Domingues; Molly Baringer, Gustavo Goni
PubDate: 2016-09-19T18:35:31.731373-05:
DOI: 10.1002/2016JC012070

• Identification and classification of very‐low frequency waves on a
coral reef flat
• Authors: Matthijs Gawehn; Ap van Dongeren, Arnold van Rooijen, Curt Storlazzi, Olivia M. Cheriton, Ad Reniers
Abstract: Very‐low frequency (VLF, 0.001‐0.005 Hz) waves are important drivers of flooding of low‐lying coral reef‐islands. In particular, VLF wave resonance is known to drive large wave runup and subsequent overwash. Using a five‐month dataset of water levels and waves collected along a cross‐reef transect on Roi‐Namur Island in the Republic of the Marshall Islands, the observed VLF motions were categorized into four different classes: (1) resonant, (2) (non‐resonant) standing, (3) progressive‐growing and (4) progressive‐dissipative waves. Each VLF class is set by the reef flat water depth and, in the case of resonance, the incident‐band offshore wave period. Using an improved method to identify VLF wave resonance, we find that VLF wave resonance caused prolonged (∼0.5 – 6.0 hr), large‐amplitude water surface oscillations at the inner reef flat ranging in wave height from 0.14 to 0.83 m. It was induced by relatively long‐period, grouped, incident‐band waves, and occurred under both storm and non‐storm conditions. Moreover, observed resonant VLF waves had non‐linear, bore‐like wave shapes, which likely have a larger impact on the shoreline than regular, sinusoidal waveforms. As an alternative technique to the commonly used Fast Fourier Transformation, we propose the Hilbert‐Huang Transformation that is more computationally expensive but can capture the wave shape more accurately. This research demonstrates that understanding VLF waves on reef flats is important for evaluating coastal flooding hazards. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-19T18:30:26.986267-05:
DOI: 10.1002/2016JC011834

• Glider observations of enhanced deep water upwelling at a shelf break
canyon: A mechanism for cross‐slope carbon and nutrient exchange
• Authors: M. Porter; M. E. Inall, J. Hopkins, M. R. Palmer, A. C. Dale, D. Aleynik, J. A. Barth, C. Mahaffey, D. A. Smeed
PubDate: 2016-09-19T18:30:21.487541-05:
DOI: 10.1002/2016JC012087

• Surface shear stress dependence of gas transfer velocity parameterizations
using DNS
• Authors: S. T. Fredriksson; L. Arneborg, H. Nilsson, R. A. Handler
Abstract: Air‐water gas‐exchange is studied in direct numerical simulations (DNS) of free‐surface flows driven by natural convection and weak winds. The wind is modeled as a constant surface‐shear‐stress and the gas‐transfer is modeled via a passive scalar. The simulations are characterized via a Richardson number Ri=Bν/u*4 where B, v, and u* are the buoyancy flux, kinematic viscosity, and friction velocity respectively. The simulations comprise 0 < Ri < ∞ ranging from convection‐dominated to shear‐dominated cases. The results are used to: (i) evaluate parameterizations of the air‐water gas‐exchange, (ii) determine, for a given buoyancy flux, the wind speed at which gas transfer becomes primarily shear driven, and (iii) find an expression for the gas‐transfer velocity for flows driven by both convection and shear. The evaluated gas transfer‐velocity parametrizations are based on either the rate of turbulent kinetic energy dissipation, the surface flow‐divergence, the surface heat‐flux, or the wind‐speed. The parametrizations using dissipation or divergence show an unfavorable Ri dependence for flows with combined forcing whereas the parametrization using heat‐flux only shows a limited Ri dependence. The two parametrizations using wind speed give reasonable estimates for the transfer‐velocity, depending however on the surface heat‐flux. The transition from convection‐ to shear‐dominated gas‐transfer‐velocity is shown to be at Ri ≈ 0.004. Furthermore, the gas‐transfer is shown to be well represented by two different approaches: (i) additive forcing expressed as kg,sum = AShear u* (Ri/Ric+1)1/4 Sc‐n where Ric = (AShear/ABuoy)4, and (ii) either buoyancy or shear dominated expressed as, kg = ABuoy (Bv)1/4Sc‐n, Ri>Ric or kg = Ashearu*Sc‐n, Ri
PubDate: 2016-09-15T18:06:09.423857-05:
DOI: 10.1002/2016JC011852

• Trapping of the near‐inertial wave wakes of two consecutive
hurricanes in the Loop Current
• Authors: E. Pallàs‐Sanz; J. Candela, J. Sheinbaum, J. Ochoa, J. Jouanno
PubDate: 2016-09-15T18:00:56.412806-05:
DOI: 10.1002/2015JC011592

• Impacts of mesoscale activity on the water masses and circulation in the
Coral Sea
• Authors: L. Rousselet; A.M. Doglioli, C. Maes, B. Blanke, A. Petrenko
Abstract: The climatological vision of the circulation within the Coral Sea is today well established with the westward circulation of two main jets, the North Caledonian Jet (NCJ) and the North Vanuatu Jet (NVJ) as a consequence of the separation of the South Equatorial Current (SEC) on the islands of New Caledonia, Vanuatu and Fiji. Each jet has its own dynamic and transports different water masses across the Coral Sea. The influence of mesoscale activity on mean flow and on water mass exchanges is not yet fully explored in this region of intense activity. Our study relies on the analysis of in situ, satellite and numerical data. Indeed we first use in situ data from the Bifurcation cruise and from an Argo float, jointly with satellite‐derived velocities, to study the eddy influence on the Coral Sea dynamics. We identify an anticyclonic eddy as participating in the transport of NVJ‐like water masses into the theoretical pathway of NCJ waters. This transfer from the NVJ to the NCJ is confirmed over the long‐term by a Lagrangian analysis. In particular, this numerical analysis shows that anticyclonic eddies can contribute up to 70% to 90% of the overall eddy transfer between those seemingly independent jets. Finally, transports calculated using S‐ADCP measurements (0‐500 m) show an eddy‐induced sensitivity that can reach up to 15 Sv, i.e, the order of the transport of the jets. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-15T08:30:53.907375-05:
DOI: 10.1002/2016JC011861

• Improving the simulation of landfast ice by combining tensile strength and
a parameterization for grounded ridges
• Authors: Jean‐François Lemieux; Frédéric Dupont, Philippe Blain, François Roy, Gregory C. Smith, Gregory M. Flato
PubDate: 2016-09-10T10:30:22.49546-05:0
DOI: 10.1002/2016JC012006

• Remote Forcing of Subsurface Currents and Temperatures near the Northern
Limit of the California Current System
• Authors: Zelalem Engida; Adam Monahan, Debby Ianson, Richard E. Thomson
Abstract: Local and remote wind forcing of upwelling along continental shelves of coastal upwelling regions play key roles in driving biogeochemical fluxes, including vertical net fluxes of carbon and nutrients. These fluxes are responsible for high primary productivity, which in turn supports a lucrative fishery in these regions. However, the relative contributions of local versus remote wind forcing is not well quantified or understood. We present results of coherence analyses between currents at a single mooring site (48.5° N, 126° W) in the northern portion of the California Current System (CalCS) from 1989–2008 and coincident time series of North America Regional Reanalysis (NARR) 10 m wind stress within the CalCS (36–54° N, 120–132° W). The two‐decade long current records from the three shallowest depths (35, 100 and 175 m) show a remote response to winds from as far south as 36° N. In contrast, only temperatures at the deepest depth (400 m) show strong coherences with remote winds. Weaker local wind influence is observed in both the currents and 400 m temperatures but is mostly due to the large spatial coherence within the wind field itself. Lack of coherence between distal winds and the 400 m currents suggests that the temperature variations at that depth are driven by vertical motion resulting from poleward travelling coastal trapped waves (CTWs). Understanding the effects of remote forcing in coastal upwelling regions is necessary for determining the occurrence and timing of extreme conditions in coastal oceans, and their subsequent impact on marine ecosystems. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-10T10:25:30.534334-05:
DOI: 10.1002/2016JC011880

• Observed subseasonal variability of heat flux and the SST response of the
tropical Indian Ocean
• Authors: Sindu Raj Parampil; G. N. Bharathraj, Matthew Harrison, Debasis Sengupta
PubDate: 2016-09-09T10:15:53.136856-05:
DOI: 10.1002/2016JC011948

• Temporal variability in the Antarctic Polar Front (2002‐2014)
• Authors: Natalie M. Freeman; Nicole S. Lovenduski, Peter R. Gent
Abstract: We investigate intra‐annual to interannual variability in the Antarctic Polar Front (PF) using weekly PF realizations spanning 2002 to 2014 (found at doi.pangaea.de/10.1594/PANGAEA.855640). While several PF studies have used gradient maxima in sea surface temperature (SST) or height to define its location, results from this study are based on a PF defined using SST measurements that avoid cloud contamination and the influence of steric sea level change. With a few regional exceptions, we find that the latitudinal position of the PF does not vary seasonally, yet its temperature exhibits a clear seasonal cycle. Consistent with previous studies, the position and intensity of the PF is largely influenced by bathymetry; generally, over steep topography we find that the front intensifies and interannual variability in its position is low. We also investigate drivers of PF variability in the context of large‐scale climate variability on various spatial and temporal scales, but find that the major modes of Southern Hemisphere climate variability explain only a tiny fraction of the interannual PF variance. Over the study time period, the PF intensifies at nearly all longitudes while exhibiting no discernible meridional displacement in its zonal mean path. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-08T03:55:33.75221-05:0
DOI: 10.1002/2016JC012145

• A modulating effect of tropical instability wave (TIW)‐induced surface
wind feedback in a hybrid coupled model of the tropical Pacific
• Authors: Rong‐Hua Zhang
PubDate: 2016-09-02T14:05:31.92588-05:0
DOI: 10.1002/2015JC011567

• Diagnosing cross‐shelf transport along an ocean front: an observational
case study in the Gulf of Lion
• Authors: F. Nencioli; A. A. Petrenko, A. M. Doglioli
PubDate: 2016-08-29T09:15:33.094553-05:
DOI: 10.1002/2016JC011908

• Alongcoast structure and interannual variability of seasonal midshelf
water properties and velocity in the Northern California Current System
• Authors: B. Hickey; S. Geier, N. Kachel, S. Ramp, P. M. Kosro, T. Connolly
Abstract: Moored sensors were maintained for ∼5 years on the northern California Current System (CCS) midshelf. The alongcoast sensor array spanned the area of influence of the plume from the Columbia River, several submarine canyons, as well as a coastal promontory where the equatorward coastal jet frequently separates from the shelf. Upwelling‐favorable wind stress magnitude decreases poleward by more than a factor of three over the latitudinal range and shelf width varies by a factor of two. In spite of the alongcoast structure in setting, both seasonal and interannual patterns in subsurface layer water properties were remarkably similar at all sites. Higher in the water column, freshwater forcing was substantial. Because of the near surface freshwater input, seasonal sea surface and subsurface temperatures were almost perfectly out of phase in the northernmost CCS (WA and OR), with a mid water column inversion in winter. Year to year differences in subsurface layer wintertime water properties were similar to spatial and temporal patterns of wind stress variability: little alongcoast structure except in salinity, but pronounced interannual differences. Summertime wind and property patterns were the opposite of those in winter: pronounced alongcoast wind stress structure, but little or no alongcoast or interannual variability in water property extremes, and only a weak relationship to local wind stress. Summertime interannual water property variability, including source waters, was shown to be more consistent with “remote forcing” via larger scale wind stress rather than with local wind stress, particularly in the northernmost CCS. This article is protected by copyright. All rights reserved.
PubDate: 2016-08-24T03:56:02.562191-05:
DOI: 10.1002/2015JC011424

• Asymmetric oceanic response to a hurricane: Deepwater observations during
Hurricane Isaac
• Authors: Laura J. Spencer; Steven F. DiMarco, Zhankun Wang, Joseph J. Kuehl, David A. Brooks
Abstract: The eye of Hurricane Isaac passed through the center of an array of six deepwater water‐column current meter moorings deployed in the northern Gulf of Mexico. The trajectory of the hurricane provided for a unique opportunity to quantify differences in the full water‐column oceanic response to a hurricane to the left and right of the hurricane trajectory. Prior to the storm passage, relative vorticity on the right side of the hurricane was strongly negative; while on the left, relative vorticity was positive. This resulted in an asymmetry in the near inertial frequencies oceanic response at depth and horizontally. A shift in the response to a slightly larger inertial frequencies ∼1.11f was observed and verified by theory. Additionally, the storm passage coincided with an asymmetric change in relative vorticity in the upper 1000 m, which persisted for ∼15 inertial periods. Vertical propagation of inertial energy was estimated at 29 m/day, while horizontal propagation at this frequency was approximately 5.7 km/day. Wavelet analysis showed two distinct sub‐inertial responses, one with a period of 2‐5 days and another with a period of 5‐12 days. Analysis of the sub‐inertial bands reveals that the spatial and temporal scales are shorter and less persistent than the near‐inertial variance. As the array is geographically located near the site of the Deepwater Horizon oil spill, the spatial and temporal scales of response have significant implications for the fate, transport, and distribution of hydrocarbons following a deepwater spill event. This article is protected by copyright. All rights reserved.
PubDate: 2016-07-18T03:57:13.921395-05:
DOI: 10.1002/2015JC011560

• Issue Information
• Pages: 7215 - 7217
PubDate: 2016-11-22T01:31:29.876017-05:
DOI: 10.1002/jgrc.21410

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