bluuebunny/crossref_metadata_2025_split huggingface dataset:
Importance of mesoscale eddies and mean circulation in ventilation of the Southern Ocean
Authors: Kamenkovich Igor , Garraffo Zulema , Pennel Romain , Fine Rana A. 
Published: March 2017

AbstractThis study examines the relative importance of the mean advection and mesoscale currents in the property exchange between the Southern Ocean mixed layer and downstream in the upper 2000 m; this exchange is referred to as ventilation. A new, highly efficient off‐line tracer model employed here uses precalculated velocities to advect dynamically passive tracers. Two idealized tracers are considered: the Boundary Impulse Response (BIR) tracer, which helps to determine the ventilation pathways and time scales, and the Transient Surface Tracer (TST), which is relevant to transient atmospheric tracers. The importance of eddies is isolated by contrasting the control simulation with a simulation without mesoscale currents. The analysis reveals complex three‐dimensional ventilation pathways, controlled by the interplay between the mean advection and eddy‐induced spreading. The mean currents carry the tracers eastward within ACC and contribute to the formation of the Antarctic Intermediate Water (AAIW) in the South Pacific and South Atlantic. The main effect of eddies is to disperse tracers away from the mean pathways, and this dispersion acts to retain the BIR tracer in the Atlantic and Indian sectors and reduce the upstream influence of these regions on the South Pacific. In addition, the eddy‐induced along‐isopycnal spreading within ACC increases the ventilated depth and the inventory of TST. The results can be used to interpret distribution of tracers in the ocean in numerical simulations and observations.
Striations and preferred eddy tracks triggered by topographic steering of the background flow in the eastern South Pacific
Authors: Belmadani Ali , Concha Emilio , Donoso David , Chaigneau Alexis , Colas François , Maximenko Nikolai , Di Lorenzo Emanuele 
Published: March 2017

AbstractIn recent years, persistent quasi‐zonal jets or striations have been ubiquitously detected in the world ocean using satellite and in situ data as well as numerical models. This study aims at determining the role of mesoscale eddies in the generation and persistence of striations off Chile in the eastern South Pacific. A 50 year climatological integration of an eddy‐resolving numerical ocean model is used to assess the long‐term persistence of striations. Automated eddy tracking algorithms are applied to the model outputs and altimetry data. Results reveal that striations coincide with both polarized eddy tracks and the offshore formation of new eddies in the subtropical front and coastal transition zone, without any significant decay over time that discards random eddies as a primary driver of the striations. Localized patches of vortex stretching and relative vorticity advection, alternating meridionally near the eastern edge of the subtropical front, are associated with topographic steering of the background flow in the presence of steep topography, and with baroclinically and barotropically unstable meridional flow. These sinks and sources of vorticity are suggested to generate the banded structure further west, consistently with a β‐plume mechanism. On the other hand, zonal/meridional eddy advection of relative vorticity and the associated Reynolds stress covariance are consistent with eddy deformation over rough topography and participate to sustain the striations in the far field. Shear instability of mean striations is proposed to feedback onto the eddy field, acting to maintain the subtropical front eddy streets and thus the striations.
Response of theKuroshioExtension path state to near‐term global warming in CMIP5 experiments with MIROC4h
Authors: Li Rui , Jing Zhao , Chen Zhaohui , Wu Lixin 
Published: March 2017

AbstractIn this study, responses of the Kuroshio Extension (KE) path state to near‐term (2006–2035) global warming are investigated using a Kuroshio‐resolving atmosphere‐ocean coupled model. Under the representative concentration pathway 4.5 (RCP4.5) forcing, the KE system is intensified and its path state tends to move northward and becomes more stable. It is suggested that the local anticyclonic wind stress anomalies in the KE region favor the spin‐up of the southern recirculation gyre, and the remote effect induced by the anticyclonic wind stress anomalies over the central and eastern midlatitude North Pacific also contributes to the stabilization of the KE system substantially. The dominant role of wind stress forcing on KE variability under near‐term global warming is further confirmed by adopting a linear 1.5 layer reduced‐gravity model forced by wind stress curl field from the present climate model. It is also found that the main contributing longitudinal band for KE index (KEI) moves westward in response to the warmed climate. This results from the northwestward expansion of the large‐scale sea level pressure (SLP) field.
Downstream evolution of the Kuroshio's time‐varying transport and velocity structure
Authors: Andres M. , Mensah V. , Jan S. , Chang M.‐H. , Yang Y.‐J. , Lee C. M. , Ma B. , Sanford T. B. 
Published: March 2017

AbstractObservations from two companion field programs—Origins of the Kuroshio and Mindanao Current (OKMC) and Observations of Kuroshio Transport Variability (OKTV)—are used here to examine the Kuroshio's temporal and spatial evolution. Kuroshio strength and velocity structure were measured between June 2012 and November 2014 with pressure‐sensor equipped inverted echo sounders (PIESs) and upward‐looking acoustic Doppler current profilers (ADCPs) deployed across the current northeast of Luzon, Philippines, and east of Taiwan with an 8 month overlap in the two arrays' deployment periods. The time‐mean net (i.e., integrated from the surface to the bottom) absolute transport increases downstream from 7.3 Sv (±4.4 Sv standard error) northeast of Luzon to 13.7 Sv (±3.6 Sv) east of Taiwan. The observed downstream increase is consistent with the return flow predicted by the simple Sverdrup relation and the mean wind stress curl field over the North Pacific (despite the complicated bathymetry and gaps along the North Pacific western boundary). Northeast of Luzon, the Kuroshio—bounded by the 0 m s−1 isotach—is shallower than 750 dbar, while east of Taiwan areas of positive flow reach to the seafloor (3000 m). Both arrays indicate a deep counterflow beneath the poleward‐flowing Kuroshio (–10.3 ± 2.3 Sv by Luzon and −12.5 ± 1.2 Sv east of Taiwan). Time‐varying transports and velocities indicate the strong influence at both sections of westward propagating eddies from the ocean interior. Topography associated with the ridges east of Taiwan also influences the mean and time‐varying velocity structure there.
Using a 1‐D model to reproduce the diurnal variability ofSST
Authors: Karagali Ioanna , Høyer Jacob L. , Donlon Craig J. 
Published: March 2017

AbstractA wide range of applications, from air‐sea interaction studies to fisheries and biological modeling, need accurate, high resolution SST which requires that the diurnal signal is known; for many applications, diurnal estimates are necessary and should be included in blended SST products. A widely preferred approach to bridge the gap between in situ and remotely sensed measurements and obtain diurnal warming estimates at large spatial scales is modeling of the upper ocean temperature. This study uses the one‐dimensional General Ocean Turbulence Model (GOTM) to resolve diurnal signals identified from satellite SSTs and in situ measurements. Focus is given on testing and validation of different parameterizations of the basic physical processes known to influence the generation of a warm surface layer. GOTM is tested and validated using in situ measurements obtained at three locations, two in the Atlantic Ocean and one in the Baltic Sea, where different oceanographic and atmospheric conditions occur, in order to obtain an insight into its general performance. It is found that the model, with a 9 band solar absorption model rather than the standard 2 band scheme, performs well when using 3 hourly NWP forcing fields and is able to resolve daily SST variability seen both from satellite and in situ measurements. As such, and due to its low computational cost, it is proposed as a candidate model for diurnal variability estimates.
Sea‐level rise impacts on the temporal and spatial variability of extreme water levels: A case study for St. Peter‐Ording, Germany
Authors: Santamaria‐Aguilar S. , Arns A. , Vafeidis A. T. 
Published: March 2017

AbstractBoth the temporal and spatial variability of storm surge water level (WL) curves are usually not taken into account in flood risk assessments as observational data are often scarce. In addition, sea‐level rise (SLR) can further affect the variability of WLs. We analyze the temporal and spatial variability of the WL curve of 75 historical storm surge events that have been numerically simulated for St. Peter‐Ording at the German North Sea coast, considering the effects induced by three SLR scenarios (RCP 4.5, RCP 8.5, and a RCP 8.5 high end scenario). We assess potential impacts of these scenarios on two parameters related to flooding: overflow volumes and fullness. Our results indicate that due to both the temporal and spatial variability of those events the resulting overflow volume can be two or even three times greater. We observe a steepening of the WL curve with an increase of the tidal range under the three SLR scenarios, although SLR induced effects are relatively higher for the RCP 4.5. The steepening of the WL curve with SLR produces a reduction of the fullness, but the changes in overflow volumes also depend on the magnitude of the storm surge event.
Validation of sea ice models using an uncertainty‐based distance metric for multiple model variables
Authors: Urrego‐Blanco Jorge R. , Hunke Elizabeth C. , Urban Nathan M. , Jeffery Nicole , Turner Adrian K. , Langenbrunner James R. , Booker Jane M. 
Published: March 2017

AbstractWe implement a variance‐based distance metric (Dn) to objectively assess skill of sea ice models when multiple output variables or uncertainties in both model predictions and observations need to be considered. The metric compares observations and model data pairs on common spatial and temporal grids improving upon highly aggregated metrics (e.g., total sea ice extent or volume) by capturing the spatial character of model skill. The Dn metric is a gamma‐distributed statistic that is more general than the χ2 statistic commonly used to assess model fit, which requires the assumption that the model is unbiased and can only incorporate observational error in the analysis. The Dn statistic does not assume that the model is unbiased, and allows the incorporation of multiple observational data sets for the same variable and simultaneously for different variables, along with different types of variances that can characterize uncertainties in both observations and the model. This approach represents a step to establish a systematic framework for probabilistic validation of sea ice models. The methodology is also useful for model tuning by using the Dn metric as a cost function and incorporating model parametric uncertainty as part of a scheme to optimize model functionality. We apply this approach to evaluate different configurations of the standalone Los Alamos sea ice model (CICE) encompassing the parametric uncertainty in the model, and to find new sets of model configurations that produce better agreement than previous configurations between model and observational estimates of sea ice concentration and thickness.
Near‐shore talik development beneath shallow water in expanding thermokarst lakes, Old Crow Flats, Yukon
Authors: Roy‐Leveillee Pascale , Burn Christopher R. 
Published: March 2017

AbstractIt is generally assumed that permafrost is preserved beneath shallow lakes and ponds in the Western North American Arctic where water depth is less than about two thirds of the late‐winter lake ice thickness. Here we present field observations of talik development beneath water as shallow as 0.2 m despite a lake ice thickness of 1.5 m, in Old Crow Flats (OCF), YT. Conditions leading to the initiation and development of taliks beneath shallow water were investigated with field measurements of shore erosion rates, bathymetry, ice thickness, snow accumulation, and lake bottom temperature near the shores of two expanding lakes in OCF. The sensitivity of talik development to variations in lake bottom thermal regime was then investigated numerically. Where ice reached the lake bottom, talik development was controlled by the ratio of freezing degree days to thawing degree days at the lake bottom (FDDlb/TDDlb). In some cases, spatial variations in on‐ice snow depth had a minimal effect on annual mean lake bottom temperature (Tlb) but caused sufficient variations in FDDlb/TDDlb to influence talik development. Where Tlb was close to but greater than 0°C simulations indicated that the thermal offset allowed permafrost aggradation to occur under certain conditions, resulting in irregular near‐shore talik geometries. The results highlight the sensitivity of permafrost to small changes in lake bottom thermal conditions where the water column freezes through in early winter and indicate the occurrence of permafrost degradation beneath very shallow water in the near‐shore zone of Arctic ponds and lakes.
Evaluating the trade‐offs between ensemble size and ensemble resolution in an ensemble‐variational data assimilation system
Authors: Lei Lili , Whitaker Jeffrey S. 
Published: March 2017

AbstractThe current NCEP operational four‐dimensional ensemble‐variational data assimilation system uses a control forecast at T1534 resolution coupled with an 80 member ensemble at T574 resolution. Given an increase in computing resources, and assuming the control forecast resolution is fixed, would it be better to increase the ensemble size and keep the ensemble resolution the same, or increase the ensemble resolution and keep the ensemble size the same? To answer this question, experiments are conducted at reduced resolutions. Two sets of experiments are conducted which both use approximately four times more computational resources than the control experiment that uses a control forecast at T670 and an 80 member ensemble at T254. One increases the ensemble size to 320 but keeps the ensemble resolution at T254; and the other increases the ensemble resolution to T670 but retains an 80 ensemble size. When ensemble size increases to 320, turning off the static component of the background‐error covariance does not degrade performance. When the data assimilation parameters are tuned for optimal performance, increasing either ensemble size or ensemble resolution can improve the forecast performance. Increasing ensemble resolution is slightly, but significantly better than increasing ensemble size for these experiments, particularly when considering errors at smaller scales. Much of the benefit of increasing ensemble resolution comes about by eliminating the need for a deterministic control forecast and running all of the background forecasts at the same resolution. In this “single‐resolution” mode, the control forecast is replaced by an ensemble average, which reduces small‐scale errors significantly.
Simultaneous observations of traveling convection vortices: Ionosphere‐thermosphere coupling
Authors: Kim Hyomin , Lessard Marc R. , Jones Sarah L. , Lynch Kristina A. , Fernandes Philip A. , Aruliah Anasuya L. , Engebretson Mark J. , Moen Jøran I. , Oksavik Kjellmar , Yahnin Alexander G. , Yeoman Timothy K. 
Published: March 2017

AbstractWe present simultaneous observations of magnetosphere‐ionosphere‐thermosphere coupling over Svalbard during a traveling convection vortex (TCV) event. Various spaceborne and ground‐based instruments made coordinated measurements, including magnetometers, particle detectors, an all‐sky camera, European Incoherent Scatter (EISCAT) Svalbard Radar, Super Dual Auroral Radar Network (SuperDARN), and SCANning Doppler Imager (SCANDI). The instruments recorded TCVs associated with a sudden change in solar wind dynamic pressure. The data display typical features of TCVs including vortical ionospheric convection patterns seen by the ground magnetometers and SuperDARN radars and auroral precipitation near the cusp observed by the all‐sky camera. Simultaneously, electron and ion temperature enhancements with corresponding density increase from soft precipitation are also observed by the EISCAT Svalbard Radar. The ground magnetometers also detected electromagnetic ion cyclotron waves at the approximate time of the TCV arrival. This implies that they were generated by a temperature anisotropy resulting from a compression on the dayside magnetosphere. SCANDI data show a divergence in thermospheric winds during the TCVs, presumably due to thermospheric heating associated with the current closure linked to a field‐aligned current system generated by the TCVs. We conclude that solar wind pressure impulse‐related transient phenomena can affect even the upper atmospheric dynamics via current systems established by a magnetosphere‐ionosphere‐thermosphere coupling process.
Family history of cardiovascular disease and parental lifestyle behaviors are associated with offspring cardiovascular disease risk markers in childhood
Authors: Silva Danilo R. , Werneck André O. , Collings Paul J. , Fernandes Rômulo A. , Barbosa Décio S. , Ronque Enio R. V. , Sardinha Luís B. , Cyrino Edilson S. 
Published: March 2017

AbstractINTRODUCTIONCardiovascular disease risk markers have become more prevalent in childhood. To provide increased understanding of the etiology of this public health issue, we investigated associations between family characteristics with cardiovascular disease risk markers in adolescents from a developing nation.METHODSIn this cross‐sectional study data for fasting glucose, lipoproteins (LDL‐C and HDL‐C), triglycerides, and total cholesterol were collected from 991 adolescents aged 10–17 who were recruited from public schools in Londrina city, Southern Brazil. Family history of cardiovascular disease and parental engagement in risk behavior (alcohol consumption and tobacco smoking) were collected using a self‐reported parental questionnaire. Socioeconomic status, adolescent physical activity (estimated by Baecke questionnaire), self‐reported tobacco and alcohol intake, and somatic maturation (age at peak height velocity) were used as covariates. Logistic regression was used for the main analyses.RESULTSIndependent of adolescent lifestyle behaviors, associations (ORadj [95% CI]) were found between: (1) paternal family history of cardiovascular disease with increased likelihood of high adolescent offspring BMI (1.53 [1.01 to 2.32]) and high triglycerides (2.93 [1.04 to 8.27]); (2) maternal family history of cardiovascular disease with heightened odds of high adolescent offspring triglycerides (2.84 [1.02 to 7.91]); (3) maternal cardiovascular disease with higher odds of high fasting glucose (2.16 [1.13 to 4.14]), and (4) maternal smoking with increased odds of high LDL‐C (1.78 [1.14 to 2.79]) and high total cholesterol (1.77 [1.01 to 3.10]) in adolescent offspring.CONCLUSIONFamily history of cardiovascular disease and maternal tobacco smoking are related to increased cardiovascular risk in adolescents, potentially independent of their own lifestyle behaviors.
Solid–solid phase‐change materials based on hyperbranched polyurethane for thermal energy storage
Authors: Du Xiaosheng , Wang Haibo , Wu Yan , Du Zongliang , Cheng Xu 
Published: March 2017

ABSTRACTA hyperbranched polyol (HBP) was synthesized with poly(ethylene glycol) (PEG) as the core molecule and 2,2‐bis(hydroxymethyl) propionic acid as the chain extender. Then, a series of hyperbranched polyurethane phase‐change materials (HP‐PCMs) with different crosslinking densities was synthesized with isophorone diisocyanate and HBP as a molecular skeleton and PEG 6000 as a phase‐change ingredient. 1H‐NMR, gel permeation chromatography, and Fourier transform infrared spectroscopy confirmed the successful synthesis of the HBP and HP‐PCMs. The polarization optical microscopy and wide‐angle X‐ray diffraction results show that the HP‐PCM exhibited good crystallization properties, but the crystallinity was lower than that of PEG 6000. The analysis results from differential scanning calorimetry indicated that the HP‐PCMs were typical solid–solid phase‐change materials with suitable phase‐transition temperatures. In addition, HP‐PCM‐3, with an appropriate degree of hyperbranched structure, possessed the highest thermal transition enthalpy of 123.5 J/g. Moreover, thermal cycling testing and thermogravimetric analysis showed that the HP‐PCMs exhibited good thermal reliability and stability. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45014.
Polypropylene‐based composites reinforced with textile wastes
Authors: Araújo Rafael S. , Rezende Claudinei C. , Marques Maria F. V , Ferreira Leonardo C. , Russo Pietro , Emanuela Errico Maria , Avolio Roberto , Avella Maurizio , Gentile Gennaro 
Published: March 2017

ABSTRACTThe present work describes the preparation of polypropylene composites reinforced with cotton fibers, which were obtained from textile waste. The cellulosic fibers were bleached and then chemically modified on the surface using acetylation or silanization methods. Fourier transform infrared spectroscopy analysis and energy dispersive X‐ray spectroscopy confirmed the efficiency of both treatments. Results of thermal degradation by thermogravimetric analysis (TGA) of treated fibers indicated that the acetylated ones decreased thermal stability while the silanized fibers increased this property. The influence of the chemical modifications and fibers content in polypropylene‐based composites was studied by thermomechanical and mechanical properties (dynamic mechanical analysis and tensile tests) and thermal analyses (TGA and differential scanning calorimetry). The results showed that the addition of the obtained cellulose fibers in polypropylene caused increase of storage and Young's moduli, along with stress at break. Moreover, scanning electronic microscopy micrographs of cryofractured surfaces revealed stronger adhesion between fiber and matrix in the composites reinforced with the modified fibers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45060.
A thermomechanical study on selective dispersion and different loading of graphene oxide in polypropylene/polycarbonate blends
Authors: Tiwari Santosh K. , Oraon Ramesh , De Adhikari Amrita , Nayak Ganesh Chandra 
Published: March 2017

ABSTRACTCarbon nanofiller reinforced polymeric materials offer the opportunity to obtain materials with desired properties. In the present study, effects of different loading of graphene oxide (GO) on the compatibility, thermomechanical, and morphological properties of incompatible polypropylene (PP)/polycarbonate (PC) polymer blends were investigated. The neat blend and blend nanocomposites were prepared by using a twin‐screw extruder under controlled shear pressure to explore the role of GO on thermomechanical properties of blends. Fourier transform infrared analysis showed the presence of GO in PC phase which was further confirmed by differential scanning calorimetry and morphological analysis. It was observed that up to loading of 0.5%, GO preferable dispersed in only PC phase and then dispersed in both PP and PC phase with further increase in GO loading due to increase in viscosity of PC phase. Field emission scanning electron microscopy investigation of PNCs showed the coalescence of PC phase with increase of GO loading. Tensile analysis confirmed that 1% of GO loading produced highest reinforcement in thermomechanical properties and further increase of GO loading deteriorate the mechanical properties. Dynamic mechanical analysis also showed high storage modulus for 1% loading. Thermal stability of 1% GO loaded nanocomposite was found to be higher than other blend nanocomposites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45062.