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 Showing 1 - 17 of 17 Journals sorted alphabetically Geochemistry, Geophysics, Geosystems       (Followers: 24, SJR: 2.439, h-index: 91) Geophysical Research Letters       (Followers: 96, 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: 102) J. of Geophysical Research : Biogeosciences       (Followers: 25) J. of Geophysical Research : Earth Surface       (Followers: 47) J. of Geophysical Research : Oceans       (Followers: 42) J. of Geophysical Research : Planets       (Followers: 100) J. of Geophysical Research : Solid Earth       (Followers: 42) J. of Geophysical Research : Space Physics       (Followers: 115) Paleoceanography       (Followers: 6, SJR: 3.067, h-index: 100) Radio Science       (Followers: 36, SJR: 1.072, h-index: 59) Reviews of Geophysics       (Followers: 31, SJR: 8.833, h-index: 107) Space Weather       (Followers: 9, SJR: 1.341, h-index: 26) Tectonics       (Followers: 10, SJR: 2.628, h-index: 96) Water Resources Research       (Followers: 71, SJR: 2.661, h-index: 144)
 Journal of Geophysical Research : Oceans   [42 followers]  Follow         Partially Free Journal    ISSN (Online) 2169-9291    Published by AGU  [17 journals]
• 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

• Cross‐shelf water exchange in the East China Sea as estimated by
satellite altimetry and in situ hydrographic measurement
• Authors: Ruibin Ding; Daji Huang, Jiliang Xuan, Bernhard Mayer, Feng Zhou, Thomas Pohlmann
Abstract: Combining satellite altimetry and in situ hydrographic measurement, we estimated the cross‐shelf transport (CST) and its spatial and temporal variations across 200 m isobath in the East China Sea (ECS) from 1993 to 2014. The vertically‐integrated CST can be dynamically divided into three parts: surface Ekman transport, geostrophic transport, and bottom Ekman transport. The results show that the 22‐year‐mean, sectionally‐integrated CST to be 1.7±2.0 Sv (positive in the on‐shelf direction), comprised of bottom and surface Ekman transports of 2.7±1.0 Sv and 0.6±0.6 Sv, respectively, that are partially offset by a geostrophic transport of ‐1.5±1.7 Sv. The sectionally‐integrated CST shows significantly high power at roughly annual period from 1999‐2001, with lower power at intra‐annual period. The time‐averaged, vertically‐integrated CST to the northeast of Taiwan is the main source of sectionally‐integrated CST. The vertically‐integrated CST also shows significant variations in the 6–15 month period band to the northeast of Taiwan as well. The temporal variations of the sectionally‐integrated and vertically‐integrated CST are both controlled primarily by geostrophic transport and modulated by bottom Ekman transport. In the upper 50 m, the geostrophic current to the northeast of Taiwan exhibits large mean and significant variability. The empirical orthogonal function analysis of vertical structure of geostrophic current shows two significant modes with strong annual signal. The first mode is associated with the migration of Kuroshio axis near Taiwan, while the second mode is associated with the variation of the meander of the Kuroshio to the northeast of Taiwan. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-15T08:35:25.891586-05:
DOI: 10.1002/2016JC011972

• 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

• Characterization and Assessment of the meteotsunami hazard in northern
Lake Michigan
• Authors: Álvaro Linares; Adam J. Bechle, Chin H. Wu
Abstract: The meteotsunami hazard is assessed in northern Lake Michigan from both short‐term and long‐term records of water level, wind speed, and air pressure. Cross‐wavelet analysis reveals that meteotsunamis can be caused by atmospheric disturbances that are pressure dominated, wind dominated, or both pressure and wind forced. In total, air pressure and wind stress are found to contribute similarly to meteotsunami initiation in northern Lake Michigan. The pressure‐driven meteotsunamis tend to be associated with convective storms, whereas meteotsunamis that are mainly wind‐driven are associated more with cyclonic‐type storms. The atmospheric disturbances responsible for largest meteotsunamis in northern Lake Michigan are found to have a propagation speed close to 32 m/s and from the south to north direction. A heuristic approach is developed to estimate the maximum meteotsunami height from the atmospheric disturbance strength and velocity. Overall, the heuristic approach is shown to be an effective methodology to assess the meteotsunami hazard over a wide range of potential atmospheric disturbance conditions. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-10T10:30:25.686312-05:
DOI: 10.1002/2016JC011979

• 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

• Physical drivers of chlorophyll variability in the open South China Sea
• Authors: Wen‐Zhou Zhang; Haili Wang, Fei Chai, Guoqiang Qiu
PubDate: 2016-09-10T10:25:22.807672-05:
DOI: 10.1002/2016JC011983

• 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

• Observations of the vertical and temporal evolution of a Natal Pulse along
the Eastern Agulhas Bank
• Authors: Xavier Pivan; Marjolaine Krug, Steven Herbette
PubDate: 2016-09-08T03:55:32.652903-05:
DOI: 10.1002/2015JC011582

• Bayesian hindcast of acoustic transmission loss in the western Pacific
Ocean
• Authors: Margaret Palmsten; J. Paquin Fabre
Abstract: A Bayesian network is developed to demonstrate the feasibility of using environmental acoustic feature vectors (EAFVs) to predict underwater acoustic transmission loss (TL) versus range at two locations for a single acoustic source depth and frequency. Features for the networks are chosen based on a sensitivity analysis. The final network design resulted in a well‐trained network, with high skill, little gain error, and low bias. The capability presented here shows promise for expansion to a more generalized approach, which could be applied at varying locations, depths and frequencies to estimate acoustic performance over a highly variable oceanographic area in real‐time or near‐real‐time. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-08T03:55:30.22015-05:0
DOI: 10.1002/2016JC011982

• A tropical cyclone genesis potential index over the western North Pacific
by using oceanic parameters
• Authors: Min Zhang; Lei Zhou, Dake Chen, Chunzai Wang
Abstract: This study attempts to create a tropical cyclone (TC) genesis potential index (GPI) by considering oceanic parameters and necessary atmospheric parameters. Based on the general understanding of the oceanic impacts on the TC genesis, many candidate factors are evaluated and discriminated, resulting in a new GPI index, which is referred to as GPIocean. GPIocean includes the parameters of (1) absolute vorticity at 1000 hPa, (2) net sea surface longwave radiation, (3) mean ocean temperature in the upper mixed layer, and (4) depth of the 26°C isotherm. GPIocean is comparable to existing GPIs in representing the TC genesis over the western North Pacific on seasonal and interannual variations. The same procedure can be applied to create a similar GPI for the other ocean basins. In the context of climate change, this new index is expected to be useful for evaluating the oceanic influences on TC genesis by using ocean reanalysis products and climate model outputs. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-07T04:23:36.076128-05:
DOI: 10.1002/2016JC011851

• Surface water subduction during a downwelling event in a
semi‐enclosed bay
• Authors: Barton E.D; Torres R, Figueiras F.G, Gilcoto M, Largier J.
PubDate: 2016-09-06T10:20:30.21031-05:0
DOI: 10.1002/2016JC011950

• Contribution of Asian dust and volcanic material to the western Philippine
Sea over the last 220 kyr as inferred from grain size and Sr‐Nd isotopes

• Authors: Fuqing Jiang; Ye Zhou, Qingyun Nan, Yu Zhou, Xufeng Zheng, Tiegang Li, Anchun Li, Hongli Wang
Abstract: Asian dust and volcanogenic materials are two major components in the northwestern Pacific. Quantitatively distinguishing them and estimating their mass accumulation rates (MARs) are very important for understanding regional and global climate change. Here, we present the grain‐size composition of detrital sediments and the radiogenic strontium (Sr) and neodymium (Nd) isotopic compositions of different grain‐size fractions of detrital sediments that were recovered from the western Philippine Sea. These new records show that the different grain‐size distributions can be associated with 1) Asian dust from the western and central Chinese deserts and Chinese loess and 2) volcanogenic materials that were derived from the Luzon Islands. The MARs of this Asian dust and volcanic materials are obtained by using Weibull‐function fitting. The MARs of Asian dust and volcanic materials are coupled with the glacial‐interglacial cycle; these values are found to have been higher and more variable during the glacial period than during the interglacial period. We argue that the strengthening aridity of the Asian continent, which is connected to solar insolation and ice volume variations from orbital eccentricity, constitutes an important mechanism that drives the high MARs of glacial dust in the western Philippine Sea. The internal positive feedback of dust may be another important mechanism. The significant increase in volcanic material during the glacial period was caused by sea level changes, which were driven by the ice volume and solar insolation at high latitudes, and by strengthened precipitation from the El Niño/Southern Oscillation (ENSO), which is driven by orbital eccentricity and precession cycles on the Luzon Islands. This article is protected by copyright. All rights reserved.
PubDate: 2016-09-06T10:20:24.872305-05:
DOI: 10.1002/2016JC012000

• Estimation of Ocean Surface Currents from Maximum Cross Correlation
applied to GOCI geostationary satellite remote sensing data over the
Tsushima (Korea) Straits
• Authors: M. A. Warren; G. D. Quartly, J. D. Shutler, P. I. Miller, Y. Yoshikawa
PubDate: 2016-09-06T04:15:26.973047-05:
DOI: 10.1002/2016JC011814

• Assessing surface heat fluxes in atmospheric reanalyses with a decade of
data from the NOAA Kuroshio Extension Observatory
• Authors: Dongxiao Zhang; Meghan F. Cronin, Caihong Wen, Yan Xue, Arun Kumar, Dai McClurg
PubDate: 2016-09-02T14:20:23.681054-05:
DOI: 10.1002/2016JC011905

• Seasonal predictability of sea surface temperature anomalies over the
Kuroshio‐Oyashio Extension: Low in summer and high in winter
• Authors: Yujie Wu; Wansuo Duan, Xinyao Rong
PubDate: 2016-09-02T14:05:36.503-05:00
DOI: 10.1002/2016JC011887

• 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

• Atmospheric forcing during active convection in the Labrador Sea and its
impact on mixed‐layer depth
• Authors: Lena M. Schulze; Robert S. Pickart, G.W.K. Moore
PubDate: 2016-09-01T10:05:21.616711-05:
DOI: 10.1002/2015JC011607

• A hybrid method to estimate suspended particle sizes from satellite
measurements over Bohai Sea and Yellow Sea
• Authors: Deyong Sun; Zhongfeng Qiu, Chuanmin Hu, Shengqiang Wang, Lin Wang, Lufei Zheng, Tian Peng, Yijun He
Abstract: Particle size distribution (PSD), a measure of particle concentrations at different sizes, is of great importance to the understanding of many biogeochemical processes in coastal marine ecosystems. Here, a hybrid method, including analytical, semi‐analytical, and empirical steps, is developed to estimate PSD through the median diameter of suspended particles (Dv50). Four cruise surveys were conducted to measure optical scattering properties, particle concentrations, spectral reflectance, and particle size distributions (obtained with a LISST instrument covering a size range of 2.5‐500 μm) in coastal waters of Bohai Sea, Yellow Sea, and Jiangsu coastal region. Based on the Mie scattering theory, Dv50 is closely related to mass‐specific backscattering coefficient of suspended particles (bbp*), and their relationship is calibrated through a power model (R2=0.796, n=67, p
PubDate: 2016-08-29T10:10:23.664014-05:
DOI: 10.1002/2016JC011949

• New insights on the upper layer circulation north of the Gulf of Guinea
• Authors: Herbert G; Bourlès B, Penven P, Grelet J.
Abstract: The oceanic circulation in the upper layers of the north of the Gulf of Guinea is analyzed, as inferred from in situ observations and numerical simulations. This particular region, in spite of the presence of a coastal upwelling and its impact on resources and regional climate, is still poorly documented. Cruises carried out in the framework of different international programs (e.g. EGEE/AMMA, PIRATA) allowed to show the existence of an eastward flowing undercurrent, found under the Guinea Current, named the Guinea UnderCurrent (GUC). Numerical results from high resolution simulation allowed the description of the seasonal variability of this current. It appears that the GUC is stronger in spring and reverses westward in August‐September. We also depict the fate and the sources of the GUC based on selected trajectories from numerical particle tracking. The simulated trajectories reveal: i) a preferred route of the GUC along 4°N from Cape Palmas to Cape Three Points and following the coast east of Cape Three Points; ii) strong recirculations in the most eastern part of the Gulf of Guinea and off Cape Palmas including warm and salty waters of the South Equatorial Current; iv) a weak inflow from northern latitudes through a subsurface current flowing southward along the West African coast. In addition, Lagrangian experiments show that the GUC is not an extension of the North Equatorial UnderCurrent and confirm that this current does not penetrate into the Gulf of Guinea. This article is protected by copyright. All rights reserved.
PubDate: 2016-08-29T09:20:28.815618-05:
DOI: 10.1002/2016JC011959

• 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

• Seasonal evolution of the Yellow Sea Cold Water Mass and its interactions
with ambient hydrodynamic system
• Authors: Jianchao Li; Guangxue Li, Jishang Xu, Ping Dong, Lulu Qiao, Shidong Liu, Pingkuo Sun, Zhisong Fan
PubDate: 2016-08-29T09:15:27.859285-05:
DOI: 10.1002/2016JC012186

• Sea surface wind streaks in spaceborne synthetic aperture radar imagery
• Authors: Yuan Zhao; Xiao‐Ming Li, Jin Sha
Abstract: Wind streaks are often observed in Synthetic Aperture Radar (SAR) images. They are used to determine the sea surface wind direction for sea surface wind field retrievals. It is generally understood that visible wind streaks are caused by roll vortices in the marine atmospheric boundary layer. In this study, 227 X‐band spaceborne SAR TerraSAR‐X and TanDEM‐X images acquired from the three FiNO platforms in the North Sea and Baltic Sea were thoroughly analyzed for a comprehensive understanding of the manifestation of wind streaks in SAR images. Approximately 48.0% of the 227 SAR images displayed wind streaks, among which 67.3%, 20.0% and 12.7% occurred under unstable, neutral, stable atmospheric conditions, respectively. The proportions indicate that wind streaks are more likely to be generated from thermal convection. Further investigations suggest that the inflection point and the wind shear may be essential for the appearance of wind streaks in SAR images under stable atmospheric conditions. This article is protected by copyright. All rights reserved.
PubDate: 2016-08-29T04:10:24.087185-05:
DOI: 10.1002/2016JC012040

• The phenology of Arctic Ocean Surface warming
• Authors: Michael Steele; Suzanne Dickinson
PubDate: 2016-08-29T04:05:32.287449-05:
DOI: 10.1002/2016JC012089

• Experiments with mixing in stratified flow over a topographic ridge
• Authors: Yvan Dossmann; Madelaine G. Rosevear, Ross W. Griffiths, Andrew McC. Hogg, Graham O. Hughes, Michael Copeland
PubDate: 2016-08-25T17:45:48.081132-05:
DOI: 10.1002/2016JC011990

• Remote sensing of normalized diffuse attenuation coefficient of
• Authors: Junfang Lin; Zhongping Lee, Mike Ondrusek, Keping Du
Abstract: The diffuse attenuation of downwelling irradiance, Kd (m−1), is an important property related to light penetration and availability in aquatic ecosystems. The standard Kd(490) product (the diffuse attenuation coefficient at 490 nm) of the global oceans from satellite remote sensing has been produced with an empirical algorithm, which limits its reliability and applicability in coastal regions. More importantly, as an apparent optical property (AOP), Kd is a function of the angular distribution of the light field (e.g., solar zenith angle). The empirically derived product thus contains ambiguities when compared with in situ measurements as there is no specification regarding the corresponding solar zenith angle associated with this Kd(490) product. To overcome these shortcomings, we refined the Kd product with a product termed as the normalized diffuse attenuation coefficient (nKd, m−1), which is equivalent to the Kd in the absence of the atmosphere and with the sun at zenith. Models were developed to get nKd from both in situ measurements and ocean color remote sensing. Evaluations using field measurements indicated that the semi‐analytically derived nKd product will not only remove the ambiguities when comparing Kd values of different light fields, but will also improve the quality of such a product, therefore maximizing the value offered by satellite ocean color remote sensing. This article is protected by copyright. All rights reserved.
PubDate: 2016-08-25T05:10:33.4159-05:00
DOI: 10.1002/2016JC011895

• Seaglider surveys at Ocean Station Papa: Circulation and water mass
properties in a meander of the North Pacific current
• Authors: Noel A. Pelland; Charles C. Eriksen, Meghan F. Cronin
PubDate: 2016-08-24T05:50:31.454779-05:
DOI: 10.1002/2016JC011920

• The effect of Kuroshio current on nitrate dynamics in the southern East
China Sea revealed by nitrate isotopic composition
• Authors: Wentao Wang; Zhiming Yu, Xiuxian Song, Zaixing Wu, Yongquan Yuan, Peng Zhou, Xihua Cao
Abstract: In spring 2014 (May‒June), in the southern East China Sea (ECS) and east of Taiwan, nutrient and isotope samples were collected and analyzed. Also, dissolved oxygen (DO), chlorophyll‐a, and physical parameters were determined. The Kuroshio subsurface water intruded into the ECS and separated into two branches on the continental shelf: the nearshore Kuroshio branch current (NKBC) and the offshore Kuroshio branch current (OKBC). Nitrate concentration in the Kuroshio subsurface water slightly decreased east of Taiwan by assimilation, and was supplied by upwelling currents northeast of Taiwan. The variations of DO, nitrate and nitrogen isotopes in the bottom water showed that continuous nitrification occurred in the NKBC after intrusion into the ECS. This process might contribute to the hypoxia zone near the coast of Zhejiang Province, China. Our results also indicated that internal nitrogen cycles appeared in NKBC since the isotope fractionation ratio of oxygen and nitrogen (18ɛ:15ɛ) in NO3‐ was 1.40. The NO3‐ flux and budget were calculated in the NKBC via numerical simulations. It demonstrated that at least ∼0.52 kmol NO3‐·s−1 was produced by nitrification from DH9 to DH5 transect, and ∼0.11 kmol NO3‐·s−1 was consumed in the DH4 transect. Moreover, according to the Rayleigh model, primary production in most of southern ECS was supported by the intrusion of the Kuroshio subsurface water, causing 5‰ isotope fractionation. In some of nearshore stations which located in the northern investigated area, the assimilated nitrate was contributed from both the NKBC and coastal currents originated from the Changjiang diluted water. This article is protected by copyright. All rights reserved.
PubDate: 2016-08-24T05:40:24.59285-05:0
DOI: 10.1002/2016JC011882

• Mesoscale modulation of air‐sea CO2 flux in Drake Passage
• Authors: Hajoon Song; John Marshall, David R. Munro, Stephanie Dutkiewicz, Colm Sweeney, D. J. McGillicuddy, Ute Hausmann
PubDate: 2016-08-24T05:20:27.601083-05:
DOI: 10.1002/2016JC011714

• Western boundary currents and climate change
• Authors: Richard Seager; Isla R. Simpson
Abstract: A recent paper in Journal of Geophysical Research‐Oceans connects recent changes in atmospheric circulation to poleward movement and intensification of western boundary currents. Causes and character of past and future trends in surface wind stress and western boundary currents are discussed here. This article is protected by copyright. All rights reserved.
PubDate: 2016-08-24T05:20:21.93621-05:0
DOI: 10.1002/2016JC012156

• Forcing of recent decadal variability in the Equatorial and North Indian
Ocean
• Authors: P. R. Thompson; C. G. Piecuch, M. A. Merrifield, J. P. McCreary, E. Firing
PubDate: 2016-08-24T03:56:09.328435-05:
DOI: 10.1002/2016JC012132

• 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

• The Atlantic Water boundary current in the Nansen Basin: Transport and
mechanisms of lateral exchange
• Authors: Kjetil Våge; Robert S. Pickart, Vladimir Pavlov, Peigen Lin, Daniel J. Torres, Randi Ingvaldsen, Arild Sundfjord, Andrey Proshutinsky
Abstract: Data from a shipboard hydrographic survey near 30°E in the Nansen Basin of the Arctic Ocean are used to investigate the structure and transport of the Atlantic Water boundary current. Two high‐resolution synoptic crossings of the current indicate that it is roughly 30 km wide and weakly mid‐depth intensified. Using a previously‐determined definition of Atlantic Water, the transport of this water mass is calculated to be 1.6 ± 0.3 Sv, which is similar to the transport of Atlantic Water in the inner branch of the West Spitsbergen Current. At the time of the survey a small anti‐cyclonic eddy of Atlantic Water was situated just offshore of the boundary current. The data suggest that the feature was recently detached from the boundary current, and, due to compensating effects of temperature and salinity on the thermal wind shear, the maximum swirl speed was situated below the hydrographic property core. Two other similar features were detected within our study domain, suggesting that these eddies are common and represent an effective means of fluxing warm and salty water from the boundary current into the interior. An atmospheric low pressure system transiting south of our study area resulted in southeasterly winds prior to and during the field measurements. A comparison to hydrographic data from the Pacific Water boundary current in the Canada Basin under similar atmospheric forcing suggests that upwelling was taking place during the survey. This provides a second mechanism related to cross‐stream exchange of heat and salt in this region of the Nansen Basin. This article is protected by copyright. All rights reserved.
PubDate: 2016-08-24T03:50:58.865812-05:
DOI: 10.1002/2016JC011715

• Annual cycle and destruction of Eighteen Degree Water
• Authors: Sam Billheimer; Lynne D. Talley
PubDate: 2016-08-20T04:06:02.409243-05:
DOI: 10.1002/2016JC011799

• High export via small particles before the onset of the North Atlantic
spring bloom
• Authors: Giering S. L. C; R. Sanders, A. P. Martin, C. Lindemann, K.O. Möller, C. J. Daniels, D. J. Mayor, M. A. St. John
PubDate: 2016-08-19T09:45:29.206809-05:
DOI: 10.1002/2016JC012048

• Consequences of inhibition of mixed‐layer deepening by the West India
Coastal Current for winter phytoplankton bloom in the northeastern Arabian
Sea
• Authors: V. Vijith; P. N. Vinayachandran, V. Thushara, P. Amol, D. Shankar, A. C. Anil
Abstract: The intense winter phytoplankton bloom during November – February in the northeastern Arabian Sea (NEAS) was thought, until recently, to be controlled only by a convective deepening of the mixed layer (ML) owing to cool and dry northeasterlies. But, a recent study has shown that the deepening of the ML in the southern NEAS is inhibited by the poleward advection of low‐salinity water from the south by the West India Coastal Current (WICC). Using an Ocean General Circulation Model coupled with an ecosystem model, we investigate the consequences of the inhibition of mixed‐layer deepening for winter phytoplankton bloom in the NEAS. We show that, during the winter monsoon, the shallow ML inhibits the entrainment of nutrients in the southern NEAS. Strong (weak) positive nitrate tendency in the northern (southern) NEAS seen in the model during the winter monsoon is maintained by strong (weak) entrainment. As a result, the chlorophyll integrated to 200 m depth from the surface is lower in the southern NEAS than in the northern NEAS. The inhibition of mixed‐layer deepening in the south affects the size‐based distribution of small and large phytoplankton, nutrient limitation terms and growth rate, and their elemental composition. The WICC, which inhibits the deepening of the ML and affects the winter bloom in the NEAS, is driven by coastal Kelvin waves generated by remote winds. This paper demonstrates a mechanism by which remotely forced coastal Kelvin waves impact the biology in the north Indian Ocean. This article is protected by copyright. All rights reserved.
PubDate: 2016-08-19T09:35:30.038659-05:
DOI: 10.1002/2016JC012004

• Estimating dense water volume and its evolution for the year 2012‐2013
in the North‐western Mediterranean Sea: An observing system simulation
experiment approach
• Authors: Robin Waldman; Samuel Somot, Marine Herrmann, Pierre Testor, Claude Estournel, Florence Sevault, Louis Prieur, Laurent Mortier, Laurent Coppola, Vincent Taillandier, Pascal Conan, Denis Dausse
Abstract: The northwestern Mediterranean (NWMed) sea includes one of the best observed ocean deep convection sites in the World. An Observing System Simulation Experiment (OSSE) is developed to provide a methodology for estimating observing network errors. It is applied to quantify dense water volumes in the NWMed during 2012‐2013 with their observation error from MOOSE network.Results from the OSSE show low spatio‐temporal sampling errors, which confirms MOOSE network ability to measure dense waters. However, results are highly sensitive to instrumental stability.The dense water volume is then estimated in observations from four ship cruises between summers 2012 and 2013. A large seasonal cycle is found, maximal in spring 2013 and dominated by the area west of 6.5°E. The dense water volume (σ0>29.11kg/m3) is stable between summer 2012 (13.3±0.6 1013m3) and winter 2013 (13.7±1.3 1013m3). It increases dramatically in spring 2013 (17.7±0.9 1013m3) due to an intense convective event, and it finally decreases rapidly in summer 2013 (15.1±0.6 1013m3) due to restratification and spreading. We estimate an open‐sea dense water formation (DWF) rate of 1.4±0.3Sυ between summer 2012 and spring 2013 over the studied area, extrapolated to 2.3±0.5Sυ over the whole NWMed sea and for the optimal timing. This is to our knowledge the highest measured DWF rate, suggesting winter 2013 was exceptionally convective. The observed restratification rate between spring and summer 2013 is ‐0.8±0.4S4Sυ. This study provides robust quantifications of deep convection during an exceptional event that will allow to evaluate numerical simulations. This article is protected by copyright. All rights reserved.
PubDate: 2016-08-19T09:35:26.150189-05:
DOI: 10.1002/2016JC011694

• An ensemble of ocean reanalyses for 1815–2013 with sparse
observational input
• Authors: Benjamin S. Giese; Howard F. Seidel, Gilbert P. Compo, Prashant D. Sardeshmukh
PubDate: 2016-08-18T06:20:49.310455-05:
DOI: 10.1002/2016JC012079

• Geochemical observations within the water column at the CO2‐rich
hydrothermal systems Hatoma Knoll and Yonaguni Knoll IV, in the southern
Okinawa Trough
• Authors: Stine Kedzior; Antje Buß, Bernd Schneider, Jens Schneider von Deimling, Jürgen Sültenfuß, Maren Walter, Christian Mertens, Gregor Rehder
PubDate: 2016-08-18T06:16:35.563099-05:
DOI: 10.1002/2016JC012003

• Upstream control of the frontal jet regulating plankton production in the
Alboran Sea (Western Mediterranean)
• Authors: Temel Oguz; Baptiste Mourre, Joaquín Tintoré
PubDate: 2016-08-18T06:16:23.855833-05:
DOI: 10.1002/2016JC011667

• How does Subantarctic Mode Water ventilate the Southern Hemisphere
subtropics?
• Authors: Daniel C. Jones; Andrew J.S. Meijers, Emily Shuckburgh, Jean‐Baptiste Sallée, Peter Haynes, Ewa Karczewska, Matthew R. Mazloff
Abstract: In several regions north of the Antarctic Circumpolar Current (ACC), deep wintertime convection refreshes pools of weakly stratified subsurface water collectively referred to as Subantarctic Mode Water (SAMW). SAMW ventilates the subtropical thermocline on decadal timescales, providing nutrients for low‐latitude productivity and potentially trapping anthropogenic carbon in the deep ocean interior for centuries. In this work, we investigate the spatial structure and timescales of mode water export and associated thermocline ventilation. We use passive tracers in an eddy‐permitting, observationally‐informed Southern Ocean model to identify the pathways followed by mode waters between their formation regions and the areas where they first enter the subtropics. We find that the pathways followed by the mode water tracers are largely set by the mean geostrophic circulation. Export from the Indian and Central Pacific mode water pools is primarily driven by large‐scale gyre circulation, whereas export from the Australian and Atlantic pools is heavily influenced by the ACC. Export from the Eastern Pacific mode water pool is driven by a combination of deep boundary currents and subtropical gyre circulation. More than 50% of each mode water tracer reaches the subtropical thermocline within 50 years, with significant variability between pools. The Eastern Pacific pathway is especially efficient, with roughly 80% entering the subtropical thermocline within 50 years. The time required for 50% of the mode water tracers to leave the Southern Ocean domain varies significantly between mode water pools, from 9 years for the Indian mode water pool to roughly 40 years for the Central Pacific mode water pool. This article is protected by copyright. All rights reserved.
PubDate: 2016-08-18T06:16:17.051279-05:
DOI: 10.1002/2016JC011680

• Air‐sea interaction at the Southern Brazilian continental shelf: In
situ observations
• Authors: L. P. Pezzi; R. B. Souza, P. C. Farias, O. Acevedo, A. J. Miller
PubDate: 2016-08-18T06:15:59.672622-05:
DOI: 10.1002/2016JC011774

• Budget of organic carbon in the North‐Western Mediterranean Open Sea
over the period 2004–2008 using 3‐D coupled physical‐biogeochemical
modeling
• Authors: C. Ulses; P.‐A. Auger, K. Soetaert, P. Marsaleix, F. Diaz, L. Coppola, M.J. Herrmann, F. Kessouri, C. Estournel
Abstract: A 3D hydrodynamic‐biogeochemical coupled model has been used to estimate a budget of organic carbon and its interannual variability over the 5‐year period 2004‐2008 in the North‐Western Mediterranean Open Sea (NWMOS). The comparison of its results with in situ and satellite observations reveals that the timing and the magnitude of the convection and bloom processes during the study period, marked by contrasted atmospheric conditions, are reasonably well reproduced by the model. Model outputs show that the amount of nutrients annually injected into the surface layer is clearly linked to the intensity of the events of winter convection. During cold winters, primary production is reduced by intense mixing events but then spectacularly increases when the water column restratifies. In contrast, during mild winters, the primary production progressively and continuously increases, sustained by moderate new production followed by regenerated production. Overall, interannual variability in the annual primary production is low. The export in sub‐surface and at mid‐depth is however affected by the intensity of the convection process, with annual values twice as high during cold winters than during mild winters. Finally, the estimation of a global budget of organic carbon reveals that the NWMOS acts as a sink for the shallower areas and as a source for the Algerian and Balearic sub‐basins. This article is protected by copyright. All rights reserved.
PubDate: 2016-08-18T06:10:54.493874-05:
DOI: 10.1002/2016JC011818

• Estimation of melt pond fraction over high‐concentration Arctic sea ice
using AMSR‐E passive microwave data
• Authors: Yasuhiro Tanaka; Kazutaka Tateyama, Takao Kameda, Jennifer K. Hutchings
PubDate: 2016-08-18T06:10:29.516362-05:
DOI: 10.1002/2016JC011876

• Evaluating the use of 1d transit time distributions to infer the mean
state and variability of oceanic ventilation
• Authors: Andrew E. Shao; Sabine Mecking, LuAnne Thompson, Rolf E. Sonnerup
PubDate: 2016-08-06T03:14:14.535536-05:
DOI: 10.1002/2016JC011900

• 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: 6555 - 6556
PubDate: 2016-10-20T02:19:30.43184-05:0
DOI: 10.1002/jgrc.21409

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