bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphometry and average temperature affect lake stratification responses to climate change
Authors: Kraemer Benjamin M. , Anneville Orlane , Chandra Sudeep , Dix Margaret , Kuusisto Esko , Livingstone David M. , Rimmer Alon , Schladow S. Geoffrey , Silow Eugene , Sitoki Lewis M. , Tamatamah Rashid , Vadeboncoeur Yvonne , McIntyre Peter B. 
Published: May 2015

AbstractClimate change is affecting lake stratification with consequences for water quality and the benefits that lakes provide to society. Here we use long‐term temperature data (1970–2010) from 26 lakes around the world to show that climate change has altered lake stratification globally and that the magnitudes of lake stratification changes are primarily controlled by lake morphometry (mean depth, surface area, and volume) and mean lake temperature. Deep lakes and lakes with high average temperatures have experienced the largest changes in lake stratification even though their surface temperatures tend to be warming more slowly. These results confirm that the nonlinear relationship between water density and water temperature and the strong dependence of lake stratification on lake morphometry makes lake temperature trends relatively poor predictors of lake stratification trends.
D/H isotope ratios in the global hydrologic cycle
Authors: Good Stephen P. , Noone David , Kurita Naoyuki , Benetti Marion , Bowen Gabriel J. 
Published: May 2015

AbstractDeuterium to hydrogen (D/H) ratios in Earth's hydrologic cycle have long served as important tracers of climate processes, yet the global HDO budget remains poorly constrained because of uncertainties in the isotopic compositions of continental evapotranspiration and runoff. Here bias‐corrected satellite retrievals of HDO and H2O concentrations from the Tropospheric Emissions Spectrometer are used to estimate the marine atmospheric surface layer HDO vapor pressure deficit, from which we calculate the global flux‐weighted average oceanic evaporation isotopic composition as −37.6‰. Using these estimates, combined with D/H ratios in precipitation, global mass balance suggests H isotope compositions for global runoff and terrestrial evapotranspiration of −77.3‰ and −40.0‰, respectively. By resolving the HDO budget, we establish an accurate global baseline for geochemically enabled Earth system models, demonstrate patterns in entrainment of moisture into the marine surface layer, and determine the isotopic composition of continental fluxes critical for global ecohydrologic investigations.
Dipole tilt angle effect on magnetic reconnection locations on the magnetopause
Authors: Zhu C. B. , Zhang H. , Ge Y. S. , Pu Z. Y. , Liu W. L. , Wan W. X. , Liu L. B. , Chen Y. D. , Le H. J. , Wang Y. F. 
Published: May 2015

AbstractPlasma energy dispersion properties inside reconnection jet flows observed inside the low‐latitude boundary layer are used to determine the distances of observing satellites to reconnection sites. The locations of the reconnection sites are then retrieved by tracing the modeled field lines by those distances. The controlling effects of the dipole tilt angle to the location of X lines or reconnection sites are investigated. Our results show that the Earth's dipole tilt angles strongly modify the location of X lines predicted by Cooling et al's model, which is thought to be the result of magnetopause reshaping due to finite dipole tilt angles.
Ionospheric and geomagnetic disturbances caused by the 2008 Wenchuan earthquake: A revisit
Authors: Zhao Biqiang , Hao Yongqiang 
Published: May 2015

AbstractPrevious works have shown that coseismic ionospheric disturbances (CIDs) after the tsunamigenic 2011 Tohoku earthquake (Tohoku EQ, Mw9.1) covered a vast area and were observed thousands of kilometers away from the epicenter. For the purpose of making a comprehensive comparison between powerful oceanic and inland EQs, we conduct a retrospective investigation of CIDs and geomagnetic responses to the 2008 Wenchuan EQ (Mw7.9) using a combination of techniques, total electron content, HF Doppler, and ground magnetometer. It is the very first study to present CIDs recorded by different techniques at co‐located sites and profiled with regard to changes of both ionospheric plasma and current (geomagnetic field) simultaneously. The integrated observation also shows that (1) in the Wenchuan case, most of the ionospheric and geomagnetic disturbances were observed within 1000 km distance which is far less than the Tohoku case; (2) two groups of CIDs were found with maximum amplitudes in the direction of azimuth 150° and 135°, respectively; and (3) the geomagnetic changes were only registered by three magnetometers located to the east and southeast of the epicenter. All the facts indicate that the main directional lobe of Wenchuan EQ energy propagation is to southeast and perpendicular to the direction of the fault rupture, but this kind of directivity is not that distinct in the Tohoku case. We suggest that the different fault slip (inland or submarine) affecting the way of couplings of lithosphere with atmosphere may contribute to the discrepancies between the two events.
The long‐wavelength geoid from three‐dimensional spherical models of thermal and thermochemical mantle convection
Authors: Liu Xi , Zhong Shijie 
Published: May 2015

AbstractThe Earth's long‐wavelength geoid anomalies have long been used to constrain the dynamics and viscosity structure of the mantle in an isochemical, whole mantle convection model. However, there is strong evidence that the seismically observed large low shear velocity provinces (LLSVPs) in the lower mantle underneath the Pacific and Africa are chemically distinct and likely denser than the ambient mantle. In this study, we have formulated dynamically self‐consistent 3‐D spherical mantle convection models to investigate how chemically distinct and dense piles above the core‐mantle boundary may influence the geoid. Our dynamic models with realistic mantle viscosity structure produce dominantly spherical harmonic degree‐2 convection, similar to that of the present‐day Earth. The models produce two broad geoid and topography highs over two major thermochemical piles in the lower mantle, consistent with the positive geoid anomalies over the Pacific and African LLSVPs. Our geoid analysis showed that the bottom layer with dense chemical piles contributes negatively to the total geoid, while the layer immediately above the chemical piles contributes positively to the geoid, canceling out the effect of the piles. Thus, the bottom part of the mantle, as a compensation layer, has zero net contribution to the total geoid, and the thickness of the compensation layer is ~1000 km or 2 to 3 times as thick as the chemical piles. Our results help constrain and interpret the large‐scale thermochemical structure of the mantle using surface observations of the geoid and topography, as well as seismic models of the mantle.
Injection‐induced seismicity: Poroelastic and earthquake nucleation effects
Authors: Segall P. , Lu S. 
Published: May 2015

AbstractThe standard model of injection‐induced seismicity considers changes in Coulomb strength due solely to changes in pore pressure. We consider two additional effects: full poroelastic coupling of stress and pore pressure, and time‐dependent earthquake nucleation. We model stress and pore pressure due to specified injection rate in a homogeneous, poroelastic medium. Stress and pore pressure are used to compute seismicity rate through the Dieterich (1994) model. For constant injection rate, the time to reach a critical seismicity rate scales with t ∼ r2/(cfc), where r is distance from the injector, c is hydraulic diffusivity, and fc is a factor that depends on mechanical properties, and weakly on r. The seismicity rate decays following a peak, consistent with some observations. During injection poroelastic coupling may increase or decrease the seismicity rate, depending on the orientation of the faults relative to the injector. If injection‐induced stresses inhibit slip, abrupt shut‐in can lead to locally sharp increases in seismicity rate; tapering the flux mitigates this effect. The maximum magnitude event has been observed to occur postinjection. We suggest the seismicity rate at a given magnitude depends on the nucleation rate, the size distribution of fault segments, and if the background shear stress is low, the time‐varying volume of perturbed crust. This leads to a rollover in frequency‐magnitude distribution for larger events, with a “corner” that increases with time. Larger events are absent at short times, but approach the background frequency with time; larger events occurring post shut‐in are thus not unexpected.
Accounting for dust aerosol size distribution in radiative transfer
Authors: Li Jiangnan , Min Qilong , Peng Yiran , Sun Zhian , Zhao Jian‐Qi 
Published: May 2015

AbstractThe impact of size distribution of mineral dust aerosol on radiative transfer was investigated using the Aerosol Robotic Network‐retrieved aerosol size distributions. Three methods for determining the aerosol optical properties using size distributions were discussed. The first is referred to as a bin method in which the aerosol optical properties are determined for each bin of the size distribution. The second is named as an assembly mean method in which the aerosol optical properties are determined with an integration of the aerosol optical parameters over the observed size distribution. The third is a normal parameterization method based on an assumed size distribution. The bin method was used to generate the benchmark results in the radiation calculations against the methods of the assembly mean, and parameterizations based on two size distribution functions, namely, lognormal and gamma were examined. It is seen that the assembly mean method can produce aerosol radiative forcing with accuracy of better than 1%. The accuracies of the parameterizations based on lognormal and gamma size distributions are about 25% and 5%, respectively. Both the lognormal and gamma size distributions can be determined by two parameters, the effective radius and effective variance. The better results from the gamma size distribution can be explained by a third parameter of skewness which is found to be useful for judging how close the assumed distribution is to the observation result. The parameterizations based on the two assumed size distributions are also evaluated in a climate model. The results show that the reflected solar fluxes over the desert areas determined by the scheme based on the gamma size distribution are about 1 W m−2 less than those from the scheme based on the lognormal size distribution, bringing the model results closer to the observations.
Reconstruction of an atmospheric tracer source in Fusion Field Trials: Analyzing resolution features
Authors: Singh Sarvesh Kumar , Turbelin Gregory , Issartel Jean‐Pierre , Kumar Pramod , Feiz Amir Ali 
Published: May 2015

AbstractReconstruction of unknown atmospheric releases using measured concentrations is an ill‐posed inverse problem. Due to insufficient measurements and dispersion model uncertainties, reliable interpretation of a retrieved source is limited by lack of resolution, nonuniqueness, and instability in the inverse solution. The study presents an optimality analysis, in terms of resolution, stability, and reliability, of an inverse solution given by a recently proposed inversion technique, called as renormalization. The inversion technique is based on an adjoint source‐receptor framework and construction of a weight function which interprets a priori information about the unknown release apparent to the monitoring network. The properties of weight function provide a perfect data resolution, maximum model resolution, and minimum variance (or stability) for the retrieved source. The reliability of the retrieved source is interpreted in view of the information derived from the geometry of the monitoring network. The inversion technique and resolution features are evaluated for a point source reconstruction using measurements from a recent dispersion experiment (Fusion Field Trials 2007) conducted at Dugway Proving Ground, Utah. With the real measurements, the point release is reconstructed within an average distance of 23 m from the true release where the average distance of the nearest receptor from the true source was 32 m. In all the trials, the point release is retrieved within 3–60 m Euclidean distance from their true location. The source strength is retrieved within a factor of 1.5 to the true release mass. The posterior uncertainty in the release parameters is observed to be within 20% of their mean value. The source localization features are resolved to its maximum extent feasible with the design of the monitoring network. The sensitivity studies are conducted to highlight the importance of receptors reporting zero concentration measurements and variations in the resolution features of the source retrieval with respect to the various arrangements of the receptors.
Lagrangian dust model simulations for a case of moist convective dust emission and transport in the western Sahara region during Fennec/LADUNEX
Authors: Sodemann H. , Lai T. M. , Marenco F. , Ryder C. L. , Flamant C. , Knippertz P. , Rosenberg P. , Bart M. , McQuaid J. B. 
Published: May 2015

AbstractDue to the harshness and inaccessibility of desert regions, the uncertainties concerning the processes of dust mobilization at the surface, airborne transport, and sedimentation are still considerable, limiting the ability to perform model simulations. In June 2011, a comprehensive data set of ground‐based and airborne in situ measurements and remote sensing observations was acquired within the Fennec/Lagrangian Dust Source Inversion Experiment (LADUNEX) field campaign in the western Sahara region. Here we evaluate the ability of the state‐of‐the‐art Lagrangian particle dispersion model FLEXPART, newly fitted with a dust mobilization capability, to simulate dust transport in this region. We investigate a case where a large mesoscale convective system (MCS) triggered dust emissions in central Mali, which subsequently moved as a large cold pool dust front toward northern Mauritania. Specifying dust mobilization for this case is shown to be an important obstacle to simulating dust transport during this event, since neither the MCS nor the associated cold pool‐causing dust emission is represented in the meteorological analysis. Obtaining a realistic dust transport simulation for this case therefore requires an inversion approach using a manual specification of the dust sources supported by satellite imagery. When compared to in situ and remote sensing data from two aircraft, the Lagrangian dust transport simulations represent the overall shape and evolution of the dust plume well. While accumulation and coarse mode dust are well represented in the simulation, giant mode particles are considerably underestimated. Our results re‐emphasize that dust emission associated with deep moist convection remains a key issue for reliable dust model simulations in northern Africa.
Is it appropriate to model turbidity currents with the three‐equation model?
Authors: Hu Peng , Pähtz Thomas , He Zhiguo 
Published: May 2015

AbstractThe three‐equation model (TEM) was developed in the 1980s to model turbidity currents (TCs) and has been widely used ever since. However, its physical justification was questioned because self‐accelerating TCs simulated with the steady TEM seemed to violate the turbulent kinetic energy balance. This violation was considered as a result of very strong sediment erosion that consumes more turbulent kinetic energy than is produced. To confine bed erosion and thus remedy this issue, the four‐equation model (FEM) was introduced by assuming a proportionality between the bed shear stress and the turbulent kinetic energy. Here we analytically proof that self‐accelerating TCs simulated with the original steady TEM actually never violate the turbulent kinetic energy balance, provided that the bed drag coefficient is not unrealistically low. We find that stronger bed erosion, surprisingly, leads to more production of turbulent kinetic energy due to conversion of potential energy of eroded material into kinetic energy of the current. Furthermore, we analytically show that, for asymptotically supercritical flow conditions, the original steady TEM always produces self‐accelerating TCs if the upstream boundary conditions (“ignition” values) are chosen appropriately, while it never does so for asymptotically subcritical flow conditions. We numerically show that our novel method to obtain the ignition values even works for Richardson numbers very near to unity. Our study also includes a comparison of the TEM and FEM closures for the bed shear stress to simulation data of a coupled Large Eddy and Discrete Element Model of sediment transport in water, which suggests that the TEM closure might be more realistic than the FEM closure.
A forward analysis on the applicability of tracer breakthrough profiles in revealing the pore structure of tight gas sandstone and carbonate rocks
Authors: Mehmani Ayaz , Mehmani Yashar , Prodanović Maša , Balhoff Matthew 
Published: May 2015

AbstractWe explore tracer breakthrough profiles (TBP) as a macroscopic property to infer the pore‐space topology of tight gas sandstone and carbonate rocks at the core scale. The following features were modeled via three‐dimensional multiscale networks: microporosity within dissolved grains and pore‐filling clay, cementation in the absence and presence of microporosity (each classified into uniform, pore‐preferred, and throat‐preferred modes), layering, vug, and microcrack inclusion. A priori knowledge of the extent and location of each process was assumed to be known. With the exception of an equal importance of macropores and pore‐filling micropores, TBPs show little sensitivity to the fraction of micropores present. In general, significant sensitivity of the TBPs was observed for uniform and throat‐preferred cementation. Layering parallel to the fluid flow direction had a considerable impact on TBPs whereas layering perpendicular to flow did not. Microcrack orientations seemed of minor importance in affecting TBPs.
Organic contaminant transport and fate in the subsurface: Evolution of knowledge and understanding
Authors: Essaid Hedeff I. , Bekins Barbara A. , Cozzarelli Isabelle M. 
Published: May 2015

AbstractToxic organic contaminants may enter the subsurface as slightly soluble and volatile nonaqueous phase liquids (NAPLs) or as dissolved solutes resulting in contaminant plumes emanating from the source zone. A large body of research published in Water Resources Research has been devoted to characterizing and understanding processes controlling the transport and fate of these organic contaminants and the effectiveness of natural attenuation, bioremediation, and other remedial technologies. These contributions include studies of NAPL flow, entrapment, and interphase mass transfer that have advanced from the analysis of simple systems with uniform properties and equilibrium contaminant phase partitioning to complex systems with pore‐scale and macroscale heterogeneity and rate‐limited interphase mass transfer. Understanding of the fate of dissolved organic plumes has advanced from when biodegradation was thought to require oxygen to recognition of the importance of anaerobic biodegradation, multiple redox zones, microbial enzyme kinetics, and mixing of organic contaminants and electron acceptors at plume fringes. Challenges remain in understanding the impacts of physical, chemical, biological, and hydrogeological heterogeneity, pore‐scale interactions, and mixing on the fate of organic contaminants. Further effort is needed to successfully incorporate these processes into field‐scale predictions of transport and fate. Regulations have greatly reduced the frequency of new point‐source contamination problems; however, remediation at many legacy plumes remains challenging. A number of fields of current relevance are benefiting from research advances from point‐source contaminant research. These include geologic carbon sequestration, nonpoint‐source contamination, aquifer storage and recovery, the fate of contaminants from oil and gas development, and enhanced bioremediation.
Preparation and graft‐copolymerization of hydrogenated natural rubber in latex stage
Authors: Ha Nguyen Thu , Kaneda Keisuke , Naitoh Yoshitaka , Fukuhara Lina , Kosugi Kenichiro , Kawahara Seiichi 
Published: May 2015

ABSTRACTPreparation and graft‐copolymerization of hydrogenated natural rubber are performed in latex stage after removal of proteins from the rubber with urea and surfactant. Hydrogenation of deproteinized natural rubber (DPNR) latex is carried out with palladium catalyst under hydrogen atmosphere. The hydrogenated DPNR (HDPNR) is crosslinked with a peroxide followed by graft‐copolymerization of styrene (Sty) and acrylonitrile (AN) in latex stage in order to prepare a graft‐copolymer of crosslinked HDPNR with poly(Sty‐co‐AN) (HDPNR‐graft‐PSAN). Characterization of the products is performed by nuclear magnetic resonance spectroscopy. The conversion of hydrogenation is investigated with respect to the catalyst feed, acidity (pH), and dry rubber content. In the resulting HDPNR‐graft‐PSAN, mole fraction of AN and Sty is 1.4 and 5.8 mol %, respectively. The graft‐copolymer is used to improve properties of PSAN as an impact modifier. The Charpy impact strength of crosslinked HDPNR‐graft‐PSAN/PSAN is about eight times as high as that of PSAN. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42435.
Plasmonic device based on a PAAm hydrogel/gold nanoparticles composite
Authors: Monteiro Johny Paulo , Predabon Sheila Maria , da Silva Cleiser Thiago Pereira , Radovanovic Eduardo , Girotto Emerson Marcelo 
Published: May 2015

ABSTRACTStimuli‐resposive hydrogels, such as poly(acrylamide), are smart materials that can be loaded with gold nanoparticles to explore the localized surface plasmon resonance effect to develop an optical device. Here we used electropolymerized poly(acrylamide) hydrogel for entrapped gold nanoparticles into gel structure (composite) to prepare a plasmonic device. Sensing tests were performed; for this bovine serum albumin molecules were placed into the composite by diffusion from an aqueous solution. The presence of the molecules alters the refractive index around the gold nanoparticles, changing its resonance conditions. The plasmonic band shifted ∼3.8 nm when the composite was incubated at the 20 µg/mL bovine serum albumin solution, which is a result comparable to reports elsewhere using gold nanoparticles on glass substrates. The device showed that it was possible to detect significantly low concentrations up to 10 ng/mL of protein in aqueous solution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42449.