bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intrusion dynamics of particle plumes in stratified water with weak crossflow: Application to deep ocean blowouts
Authors: Wang Dayang , Adams E. Eric 
Published: May 2016

AbstractWe present an experimental study of particle plumes in ambient stratification and a mild current. In an inverted framework, the results describe the fate of oil droplets released from a deep ocean blowout. A continuous stream of dense glass beads was released from a carriage towed in a salt‐stratified tank. Nondimensional particle slip velocity UN ranged from 0.1 to 1.9, and particles with UN ≤ 0.5 were observed to enter the intrusion layer. The spatial distributions of beads, collected on a bottom sled towed with the source, present a Gaussian distribution in the transverse direction and a skewed distribution in the along‐current direction. Dimensions of the distributions increase with decreasing UN. The spreading relations can be used as input to far‐field models describing subsequent transport of particles or, in an inverted framework, oil droplets. The average particle settling velocity, Uave, was found to exceed the individual particle slip velocity, Us, which is attributed to the initial plume velocity near the point of release. Additionally, smaller particles exhibit a “group” or “secondary plume” effect as they exit the intrusion as a swarm. The secondary effect becomes more prominent as UN decreases, and might help explain observations from the 2000 Deep Spill field experiment where oil was found to surface more rapidly than predicted based on Us. An analytical model predicting the particle deposition patterns was validated against experimental measurements, and used to estimate near‐field oil transport under the Deepwater Horizon spill conditions, with/without chemical dispersants.
Internal tides recorded at ocean bottom off the coast of Southeast Taiwan
Authors: Chang Emmy T. Y. , Chao Benjamin F. , Chen Guan‐Yu , Liau Jian‐Ming 
Published: May 2016

AbstractAn ocean‐bottom experiment consisting of an array of four ocean‐bottom seismometers (OBS) was conducted off the coast of southeast Taiwan during May–July 2011. We develop comprehensive analyses of the space‐time kinematics of the tidal signals recorded in the compact high‐sensitivity temperature loggers (CHTL) and the OBS geophones at the ocean bottom with depths ranging from 1254 to 1610 m. The evidence suggests that internal tides are responsible for the recorded signals: baroclinic internal waves (mainly the M2 tide) are generated by barotropic tidal currents in the Luzon Strait. The internal tides exhibit gradual phase changing and irregularly fluctuating strength, leaving signatures in the CHTL as ambient temperature variations, signifying low‐mode wave motions within the stratified water layers; and in OBS geophones as intermittent “tremor” agitations, signifying high‐mode turbulent flows on the seafloor. The M2 internal tides across our array are found to propagate in the northeast direction at speeds ranging from 1 to 2+ m s−1. Furthermore, the internal tides are identified at the ocean‐bottom based on an operational hydrodynamic hindcast/forecast model. The simulations show good agreement with the observed temperature variation on the seafloor and substantiate the vertical velocity and displacement of the water parcel driven by the internal tides. The joint detection of the temperature and tremor signals provides further information about the interactions of internal tides with the seafloor topography and the associated energy dissipation. Our results elucidate the space‐time ubiquity of the internal tides at the ocean bottom, which is an important interface of dynamic oceanography.
Atmospheric drivers of Greenland surface melt revealed by self‐organizing maps
Authors: Mioduszewski J. R. , Rennermalm A. K. , Hammann A. , Tedesco M. , Noble E. U. , Stroeve J. C. , Mote T. L. 
Published: May 2016

AbstractRecent acceleration in surface melt on the Greenland ice sheet (GrIS) has occurred concurrently with a rapidly warming Arctic and has been connected to persistent, anomalous atmospheric circulation patterns over Greenland. To identify synoptic setups favoring enhanced GrIS surface melt and their decadal changes, we develop a summer Arctic synoptic climatology by employing self‐organizing maps. These are applied to daily 500 hPa geopotential height fields obtained from the Modern Era Retrospective Analysis for Research and Applications reanalysis, 1979–2014. Particular circulation regimes are related to meteorological conditions and GrIS surface melt estimated with outputs from the Modèle Atmosphérique Régional. Our results demonstrate that the largest positive melt anomalies occur in concert with positive height anomalies near Greenland associated with wind, temperature, and humidity patterns indicative of strong meridional transport of heat and moisture. We find an increased frequency in a 500 hPa ridge over Greenland coinciding with a 63% increase in GrIS melt between the 1979–1988 and 2005–2014 periods, with 75.0% of surface melt changes attributed to thermodynamics, 17% to dynamics, and 8.0% to a combination. We also confirm that the 2007–2012 time period has the largest dynamic forcing relative of any period but also demonstrate that increased surface energy fluxes, temperature, and moisture separate from dynamic changes contributed more to melt even during this period. This implies that GrIS surface melt is likely to continue to increase in response to an ever warmer future Arctic, regardless of future atmospheric circulation patterns.
Simulation of the urban climate in a Chinese megacity with spatially heterogeneous anthropogenic heat data
Authors: Chen Feng , Yang Xuchao , Wu Juanjia 
Published: May 2016

AbstractAnthropogenic heat release (AHR) by human activities in cities is a key contributing factor to the generation of the urban heat island (UHI) effect; thus, AHR should be incorporated into urban climate and environmental modeling. In this study, gridded AHR data with high spatial resolution (1 km) were included in the integrated weather research and forecasting (WRF)/urban modeling system to investigate the urban environment of Hangzhou City, which is the capital of Zhejiang Province in east China. The AHR data were estimated for this province based on the significant correlation between energy consumption statistics data and multisensor remote‐sensing data (namely, nighttime light imagery and a vegetation index). The coupled model was evaluated against available observational data derived from a dense automatic weather station network in Hangzhou. The effects of AHR and urban land use on the urban environment were investigated with three sensitivity numerical experiments. Results showed that the mean UHI intensity reached 0.95°C and 1.66°C in winter and in summer, respectively, and that AHR contributed 65.26% and 17.47% to UHI intensity in the two seasons. In winter, AHR significantly impacted the diurnal variation in UHI, and the two UHI intensity peaks ascribed to AHR were detected during rush hours. The impact of AHR on planetary boundary layer (PBL) height was similar to its contribution to UHI effect, with a large contribution in winter. Moreover, UHI enhanced atmospheric vertical motions, which led to precipitation changes, especially during summer. A convective and deep PBL was detected and triggered convective precipitation over or downwind of Hangzhou City during summer. Given the anticipated increase in global urban populations, characterizing the spatial‐temporal variations of AHR and its impacts is essential toward continued progress in urban climate assessment.
Comprehensive multiyear carbon budget of a temperate headwater stream
Authors: Argerich Alba , Haggerty Roy , Johnson Sherri L. , Wondzell Steven M. , Dosch Nicholas , Corson‐Rikert Hayley , Ashkenas Linda R. , Pennington Robert , Thomas Christoph K. 
Published: May 2016

AbstractHeadwater streams comprise nearly 90% of the total length of perennial channels in global catchments. They mineralize organic carbon entering from terrestrial systems, evade terrestrial carbon dioxide (CO2), and generate and remove carbon through in‐stream primary production and respiration. Despite their importance, headwater streams are often neglected in global carbon budgets primarily because of a lack of available data. We measured these processes, in detail, over a 10 year period in a stream draining a 96 ha forested watershed in western Oregon, USA. This stream, which represents only 0.4% of the watershed area, exported 159 kg C ha−1 yr−1, similar to the global exports for large rivers. Stream export was dominated by downstream transport of dissolved inorganic carbon (63 kg C ha−1 yr−1) and by evasion of CO2 to the atmosphere (42 kg C ha−1 yr−1), leaving the remainder of 51 kg C ha−1 yr−1 for downstream transport of organic carbon (17 kg C ha−1 yr−1 and 34 kg C ha−1 yr−1 in dissolved and particulate form, respectively).
Effects of cumulus parameterization closures on simulations of summer precipitation over the United States coastal oceans
Authors: Qiao Fengxue , Liang Xin‐Zhong 
Published: May 2016

AbstractThis study evaluates the effects of major cumulus parameterization closures on summer precipitation simulations over the U.S. Atlantic Coasts and Gulf of Mexico. A series of mesoscale regional climate model simulations using an Ensemble Cumulus Parameterization (ECP) that incorporates multiple alternate closure schemes into a single cloud model formulation are conducted and compared to determine the systematic errors and relative performances of individual and combined closures in capturing precipitation spatiotemporal variations. The results show that closure algorithms largely affect precipitation's geographic distribution, frequency and intensity, and diurnal cycle. The quasi‐equilibrium and total instability adjustment closures simulate widespread wet biases, while the instability tendency closure produces systematic dry biases. Two closure algorithms based on the average vertical velocity at the cloud base and column moisture convergence complementarily reproduce the observed precipitation pattern and amount, and capture the frequency of heavy rainfall events better than other closures. In contrast, the instability tendency closures are better at capturing the diurnal phase but yield much larger deficits in amount. Therefore, cloud base vertical velocity and moisture convergence may be the primary factors controlling precipitation seasonal mean and daily variation, while the instability tendency may play a critical role in regulating the diurnal cycle phase.
On the formation of Ganymede's surface brightness asymmetries: Kinetic simulations of Ganymede's magnetosphere
Authors: Fatemi S. , Poppe A. R. , Khurana K. K. , Holmström M. , Delory G. T. 
Published: May 2016

AbstractGanymede possesses strong surface brightness asymmetries both between its polar cap and equatorial regions and between its leading and trailing hemispheres. Here we test the hypothesis that these asymmetries are due to differential Jovian plasma and energetic particle precipitation to the surface with the combination of a hybrid plasma model (kinetic ions and fluid electrons) and a particle tracing model. We describe the hybrid model, the first of its kind applied to Ganymede, and compare the results to both Galileo observations and previous MHD and MHD‐EPIC models of Ganymede. We calculate spatially resolved precipitating Jovian ion fluxes to the surface of Ganymede for energies 1 < E < 104 keV and find (1) precipitating fluxes peak near 100 keV and (2) excellent correlation between the precipitating flux and Ganymede's surface brightness variations. Thus, we conclude that precipitating energetic particle fluxes are the primary driver for altering the surface brightness of Ganymede.
Drivers of δ2H variations in an idealized extratropical cyclone
Authors: Dütsch Marina , Pfahl Stephan , Wernli Heini 
Published: May 2016

AbstractNumerical model simulations of stable water isotopes help to improve our understanding of the complex processes driving isotopic variability in atmospheric moisture. We use the isotope‐enabled Consortium for Small‐Scale Modelling (COSMO) model to study the governing mechanisms of δ2H variations in an idealized extratropical cyclone. A set of experiments with differing initial conditions of δ2H in vapor and partly deactivated isotopic fractionation allows us to quantify the relative roles of cloud fractionation and vertical and horizontal advection for the simulated δ2H signals associated with the cyclone and fronts. Horizontal transport determines the large‐scale pattern of δ2H in both vapor and precipitation, while fractionation and vertical transport are more important on a smaller scale, near the fronts. During the passage of the cold front fractionation leads to a V‐shaped trend of δ2H in precipitation and vapor, which is, for vapor, superimposed on a gradual decrease caused by the arrival of colder air masses.
Ocean chemistry, ocean warming, and emerging hypoxia: Commentary
Authors: Brewer Peter G. , Peltzer Edward T. 
Published: May 2016

AbstractFor 50 years, ocean scientists have represented deep sea biogeochemical rates as a temperature independent function of depth with form R = R0e−αz where z is depth in km. We show this resembles, but is not an identity for, a form of the classical Arrhenius equation K = Ae−Ea/RT where T is temperature in Kelvins, R is the gas constant (8.314 JK−1mol−1), and A is a preexponential factor. For a deep Sargasso Sea data set, we find oxygen consumption rates are accurately represented by an Arrhenius process with apparent activation energy of 86.5 kJ mol−1, and Q10 = 3.63.
Remote sensing of nearshore wave interference
Authors: Smit P. B. , Bland R. , Janssen T. T. , Laughlin B. 
Published: May 2016

AbstractWave focusing of energetic swell fields can result in small‐scale variations associated with coherent interference that can be important for nearshore circulation and beach dynamics. However, coherent interference is difficult to measure with conventional in situ instruments and is not accounted for in operational wave models. As a result, such effects are generally ignored. In this work, we analyze X‐band radar observations collected at Ocean Beach, San Francisco using a Wigner‐Ville or coupled‐mode spectrum, to show how long‐dwell remote sensing technology allows us to identify coherent wave interference. Our analysis demonstrates that during energetic swell events, the nearshore wave field consists of two noncollinear, but coherent, swell patterns that originate from the same offshore source but are directionally separated due to refraction over the San Francisco Bar. The length scale of the associated alongshore wave height variability (200 m) is consistent with the wavenumber separation obtained from the coupled mode analysis. This confirms that the small‐scale variability is primarily due to coherent interference. In addition, our analysis shows that the shoreline exhibits a strong localized response near the radar site on the 200 m scale, which suggests that coherent interference effects can affect wave‐driven nearshore transport processes and localized erosion.
Thermal perturbation, mineral assemblages, and rheology variations induced by dyke emplacement in the crust
Authors: Lavecchia Alessio , Clark Stuart R. , Beekman Fred , Cloetingh Sierd A. P. L. , Burov Evgueni 
Published: May 2016

AbstractWe constructed a thermomechanical model to examine the changes in rheology caused by the periodic intrusion of basaltic dykes in a two‐layered continental crust. Dyke intrusion can locally change the mineralogical composition of the crust in space and time as a result of temperature‐induced metamorphism. In our models we paid particular attention to determine how different mineral assemblages and reaction kinetics during metamorphism impact on the thermomechanical behavior of the crust, in terms of differential stress values. We investigated several lithologies characteristic for intracontinental crust: (1) a quartz‐feldspathic crust (QF), (2) a crust with a mineralogical assemblage resembling the average chemical composition occurring in literature (CC), and (3) a micaschist crust (MS). Our model shows that temperature profiles are weakly influenced by metamorphism, with negligible variations in the T‐t paths. The results indicate that intrusion‐induced changes in the crustal rheology are strongly dependent on mineralogical assemblage variation. The strength of a dyke aureole in the upper crust increases during dyke emplacement, which may cause migration of later dykes and influence the dyke spacing. In contrast, in the lower crust the strength of a dyke aureole decreases during dyke emplacement. Fast kinetics results in a ductile lower crust in proximity of the dykes, whereas slower kinetics leads to the formation of partial melts and subsequent switch from ductile to brittle behavior. Lithology exerts a dominant role on the quantity of melt produced, with higher volume percentages occurring in the MS case study. Produced melts may migrate and support acidic volcanic activity.
Palladium‐Catalyzed Cascade Reactions of α‐Halo‐N‐Tosylhydrazones, Indoles, and Aryl Iodides
Authors: Wu Guojiao , Deng Yifan , Luo Haiqing , Li Tianjiao , Zhang Yan , Wang Jianbo 
Published: May 2016

Abstractα‐Halo‐N‐tosylhydrazones are explored as reagents for the multiple carbon–carbon bond formations in palladium‐catalyzed three‐component reactions. A strategy has been designed for this transformation by using a nucleophile to react with the azoalkene intermediate formed in situ from the α‐halo‐N‐tosylhydrazone to generate the diazo intermediate, which is further subjected to palladium‐catalyzed C−C bond forming reactions with aryl iodides.
Prognostication of long‐term outcomes after subarachnoid hemorrhage: The FRESH score
Authors: Witsch Jens , Frey Hans‐Peter , Patel Sweta , Park Soojin , Lahiri Shouri , Schmidt J. Michael , Agarwal Sachin , Falo Maria Cristina , Velazquez Angela , Jaja Blessing , Macdonald R. Loch , Connolly E. Sander , Claassen Jan 
Published: May 2016

ObjectiveTo create a multidimensional tool to prognosticate long‐term functional, cognitive, and quality of life outcomes after spontaneous subarachnoid hemorrhage (SAH) using data up to 48 hours after admission.MethodsData were prospectively collected for 1,619 consecutive patients enrolled in the SAH outcome project July 1996 to March 2014. Linear models (LMs) were applied to identify factors associated with outcome in 1,526 patients with complete data. Twelve‐month functional, cognitive, and quality of life outcomes were measured using the modified Rankin scale (mRS), Telephone Interview for Cognitive Status, and Sickness Impact Profile. Based on the LM residuals, we constructed the FRESH score (Functional Recovery Expected after Subarachnoid Hemorrhage). Score performance, discrimination, and internal validity were tested using the area under the receiver operating characteristic curve (AUC), Nagelkerke and Cox/Snell R2, and bootstrapping. For external validation, we used a control population of SAH patients from the CONSCIOUS‐1 study (n = 413).ResultsThe FRESH score was composed of Hunt & Hess and APACHE‐II physiologic scores on admission, age, and aneurysmal rebleed within 48 hours. Separate scores to prognosticate 1‐year cognition (FRESH‐cog) and quality of life (FRESH‐quol) were developed controlling for education and premorbid disability. Poor functional outcome (mRS = 4–6) for score levels 1 through 9 respectively was present in 3, 6, 12, 38, 61, 83, 92, 98, and 100% at 1‐year follow‐up. Performance of FRESH (AUC = 0.90), FRESH‐cog (AUC = 0.80), and FRESH‐quol (AUC = 0.78) was high. External validation of our cohort using mRS as endpoint showed satisfactory results (AUC = 0.77). To allow for convenient score calculation, we built a smartphone app available for free download.InterpretationFRESH is the first clinical tool to prognosticate long‐term outcome after spontaneous SAH in a multidimensional manner. Ann Neurol 2016;80:46–58
Preparation and characterization of hyperbranched polymer modified montmorillonite/chlorinated butyl rubber damping composites
Authors: Fuhai Cao , Jincheng Wang 
Published: May 2016

ABSTRACTIn this work, Na+‐montmorillonite (MMT) was modified by hyperbranched polymer (HBP) and grafted with hindered phenol to improve the damping and other properties of the chlorinated butyl rubber (CIIR) composites. The hyperbranched polymer‐modified montmorillonite (HBP‐OMMT) was prepared by organic montmorillonite (OMMT) that was obtained from the cation exchange reaction between MMT and silane quaternary ammonium salt. The main characterization methods were Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance, X‐ray diffraction, scanning electron microscopy, energy dispersive spectrometer, and thermogravimetric (TG) analysis. The basal spacings of MMT, OMMT, and HBP‐OMMT were 1.47, 2.94, and 4.09 nm, respectively. The onset and center temperatures of decomposition (T−5% and Tmax) of HBP‐OMMT were improved from 301 and 369 °C to 332 and 398 °C, respectively. The CIIR damping composites were prepared by mechanical blending of HBP‐OMMT with pure CIIR. The tensile strength and elongation at break of the composites were improved from 5.4 MPa and 890% to 7.6 MPa and 1066%. From TG curves, T−5% and Tmax were increased from 297.4 and 406.0 °C to 323.3 and 410.5 °C, respectively. The dynamic mechanical analysis results showed that tan δ rose from the original 1.20 to 1.44 with the addition of HBP‐OMMT. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43645.
Thin film composite forward osmosis membranes with poly(2‐hydroxyethyl methacrylate) grafted nano‐TiO2 as additive in substrate
Authors: Kuang Wu , Liu Zhongnan , Kang Guodong , Liu Dandan , Zhou Meiqing , Cao Yiming 
Published: May 2016

ABSTRACTThe poly(2‐hydroxyethyl methacrylate) grafted titanium dioxide nanoparticles were synthesized and added to the substrate of flat‐sheet thin film composite forward osmosis (TFC‐FO) membranes. The hydrophilicity of substrate was improved, which was advantageous to enhance the water flux of TFC‐FO membranes. The membranes containing a 3 wt % TiO2‐PHEMA in the substrate exhibited a finger‐like structure combined with sponge‐like structure, while those with lower or without TiO2‐PHEMA content showed fully finger‐like structures. As for FO performance, the TFC‐FO membranes with 3 wt % TiO2‐PHEMA content achieved the highest water flux of 42.8 LMH and 24.2 LMH against the DI water using 2M NaCl as the draw solution tested under the active layer against draw solution (AL‐DS) mode and active layer against feed solution (AL‐FS) mode, respectively. It was proven that the hydrophilic property of membrane substrates was a strong factor influencing the water flux in FO tests. Furthermore, the structural parameter was remarkably decreased with an increase of TiO2‐PHEMA content in membrane substrate, indicating the reducing of internal concentration polarization. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43719.