bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Atmospheric Rivers in Extratropical and Polar Hydroclimate
Authors: Nash Deanna , Waliser Duane , Guan Bin , Ye Hengchun , Ralph F. Martin 
Published: June 2018

AbstractAtmospheric rivers (ARs) are narrow, long, transient, water vapor‐rich corridors of the atmosphere that are responsible for over 90% of the poleward water vapor transport in and across midlatitudes. However, the role of ARs in modulating extratropical and polar hydroclimate features (e.g., water vapor content and precipitation) has not been fully studied, even though moistening of the polar atmosphere is both a key result and amplifier of Arctic warming and sea ice melt, and precipitation is key to the surface mass balance of polar sea ice and ice sheets. This study uses the Modern‐Era Retrospective analysis for Research and Applications, Version 2 reanalysis to characterize the roles of AR water vapor transport on the column‐integrated atmospheric water vapor budget in the extratropical and polar regions of both hemispheres. Meridional water vapor transport by ARs across a given latitude (examined for 40°, 50°, 60°, and 70°) is strongly related to variations in area‐averaged (i.e., over the cap poleward of the given latitude) total water vapor storage and precipitation poleward of that latitude. For the climatological annual cycle, both AR transport (i.e., nonlocal sources) and total evaporation (i.e., local sources) are most correlated with total precipitation, although with slightly different phases. However, for monthly anomalies, the water budget at higher latitudes is largely dominated by the relationship between AR transport and precipitation. For pentad and daily anomalies, AR transport is related to both precipitation and water vapor storage variations. These results demonstrate the important role of episodic, extreme water vapor transports by ARs in modulating extratropical and polar hydroclimate.
Probabilistic Prediction and Forecast of Daily Suspended Sediment Concentration on the Upper Yangtze River
Authors: Matos José Pedro , Hassan Marwan A. , Lu Xi Xi , Franca Mário J. 
Published: June 2018

AbstractSediment transport in suspension can represent more than 90% of a river's total annual flux of sediment. In the case of the Yangtze River, more than 99% of the sediment supplied to the sea is suspended load. Suspended sediment is thus an important component of the total sediment load, with implications for channel dynamics, landscape evolution, ecology, and human‐related activities. For hydrological management of large basins such as the Yangtze River, knowledge of the processes governing suspended sediment concentration (SSC) is essential. An analysis of the temporal variation of SSC for the Upper Yangtze basin (defined at Pingshan station) is presented here. For this purpose, a database of 50 years of concurrent discharge and SSC measurements, made by the Yangtze River Commission, is used. The analysis is made using a novel probabilistic data‐driven technique, the Generalized Pareto Uncertainty (GPU). This technique allows for the testing of several strategies of prediction and forecast applied to a time series of SSC and streamflow. Changing between local or seasonal variables to feed these strategies, we inferred that although the main driver of the SSC transport is flow (as reported by previous authors), sediment storage is also a major control. Furthermore, the maximum necessary time lag for forecasts made with the data is on the order of one week, which provides one indication of the time scale of the local processes of SSC transport in the Upper Yangtze. In this paper, limitations and data requirements of the GPU methodology are also discussed.
Comment on “Large Eddy Simulation of Turbulence and Solute Transport in a Forested Headwater Stream” by Khosronejad et al.: Invalid Representation of Scalar Transport by the Act of Diffusion
Authors: Sookhak Lari Kaveh , Davis Greg B. 
Published: June 2018

AbstractAn invalid representation of diffusion‐based scalar transport in the advection‐diffusion equation in Khosronejad et al. (2016, https://doi.org/10.1002/2014JF003423) is discussed here. It is discussed that the error may increase diffusion‐based transport by up to 3 orders of magnitude where the turbulence intensity is low.
Pacific Plate Apparent Polar Wander, Hot Spot Fixity, and True Polar Wander During the Formation of the Hawaiian Island and Seamount Chain From an Analysis of the Skewness of Magnetic Anomaly 20r (44 Ma)
Authors: Zheng Lin , Gordon Richard G. , Woodworth Daniel 
Published: June 2018

AbstractWhile it is well documented that the Hawaiian hot spot has shifted southward relative to the spin axis since the formation of some of the Emperor seamounts, the paleolatitude of the hot spot during the formation of the Hawaiian chain is poorly known. To better determine the latter, here we estimate the location of the 44 Ma Pacific plate paleomagnetic pole by investigating the skewness (asymmetry) of 14 airplane and 19 ship‐board crossings of magnetic anomaly 20r between the Murray and Marquesas fracture zones on the Pacific plate. The new 44 Ma paleomagnetic pole (78.0°N, 26.0°E, A95_1 = 5.4° at 101°, A95_2 = 2.0°) differs by ≈4° from its position expected if the Pacific hot spots have been fixed relative to the spin axis. This shift is independently recorded by the chron 12r (32 Ma) Pacific plate skewness paleomagnetic pole and is also confirmed by paleomagnetic poles reconstructed from the continents, indicating that global hot spots have moved in unison with respect to the spin axis, probably due to true polar wander, which may continue today as recorded by optical astronomy and geodetic very long baseline interferometry. An analysis of spreading rates recorded in the magnetic profiles indicates that spreading rates doubled between ≈50 and ≈42 Ma (confirming prior results), as expected if the bend in the Hawaiian‐Emperor chain records a change in Pacific plate motion relative to the deep mantle.
Transient Groundwater Travel Time Distributions and Age‐Ranked Storage‐Discharge Relationships of Three Lowland Catchments
Authors: Kaandorp V. P. , de Louw P. G. B. , van der Velde Y. , Broers H. P. 
Published: June 2018

AbstractThe contribution of groundwater to streams is controlled by temporally and spatially variable groundwater flow paths with distinctive travel times. The aggregated average travel time distribution (TTD) of all these flow paths functions as a catchment characteristic. Currently, research on TTDs is expanding towards dynamic TTDs and building on this, we present dynamic backward TTDs and residence time distributions using forward particle tracking on a high‐resolution spatially distributed groundwater flow model (25*25 m). We show that the dynamic backward TTDs of three Dutch catchments are determined by the interplay between the activation of shallow short flow paths and the intensification of fluxes through all flow paths when groundwater levels rise. In addition, the preference for young water in our lowland catchments appears strongly controlled by drainage density. Variations in catchment mixing with time and between catchments were analyzed using dynamic StorAge Selection (SAS) functions. This showed the effect of differences in geology and topography on the shape of the SAS functions. Additionally, the variability of SAS functions in time was shown to depend on the extent to which new flow paths can be activated. Time‐varying SAS functions are required for computation of dynamic TTDs, and this research showed realistic values for the variability in the SAS functions of lowland catchments. The step towards dynamic TTDs is crucial for understanding the temporal and spatial behavior of streams, their chemical composition, and their ecological value.
UAVSAR and Optical Analysis of the Thomas Fire Scar and Montecito Debris Flows: Case Study of Methods for Disaster Response Using Remote Sensing Products
Authors: Donnellan Andrea , Parker Jay , Milliner Christopher , Farr Tom G. , Glasscoe Margaret , Lou Yunling , Zheng Yang , Hawkins Brian 
Published: June 2018

AbstractWe use the 2017 Thomas fire and ensuing Montecito debris flow as a case study to demonstrate how application of various interferometric synthetic aperture radar postprocessing techniques can be used to highlight the fire scar and major damage areas from the debris flows. We use National Aeronautics and Space Administration's airborne Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) L‐band polarimetric interferometric synthetic aperture radar (InSAR) for this study. Results demonstrate that a single polarimetric radar image highlights burn areas. Coherence and interferometric radar pairs show the fire scar and debris flow. An unwrapped interferogram shows the location of the debris flow over the 101 Freeway in greater detail than a raw interferogram. We enhanced the interferogram and coherence product of a pair of images acquired before and after the fire and debris flows, which highlights areas of destroyed structures and major damage. We first despeckled the images and then converted the interferogram to four colors and the coherence map to two colors. Analysis of optical imagery between before and after images shows that the debris flows are best identified using visible bands and that near‐infrared better highlights the lower part of the flows where more mud was deposited. These simplified products provide more actionable products for disaster responders; the products were downloaded for use by the State of California.
Modeling of Stick‐Slip Behavior in Sheared Granular Fault Gouge Using the Combined Finite‐Discrete Element Method
Authors: Gao Ke , Euser Bryan J. , Rougier Esteban , Guyer Robert A. , Lei Zhou , Knight Earl E. , Carmeliet Jan , Johnson Paul A. 
Published: June 2018

AbstractSheared granular layers undergoing stick‐slip behavior are broadly employed to study the physics and dynamics of earthquakes. Here a two‐dimensional implementation of the combined finite‐discrete element method (FDEM), which merges the finite element method (FEM) and the discrete element method (DEM), is used to explicitly simulate a sheared granular fault system including both gouge and plate, and to investigate the influence of different normal loads on seismic moment, macroscopic friction coefficient, kinetic energy, gouge layer thickness, and recurrence time between slips. In the FDEM model, the deformation of plates and particles is simulated using the FEM formulation while particle‐particle and particle‐plate interactions are modeled using DEM‐derived techniques. The simulated seismic moment distributions are generally consistent with those obtained from the laboratory experiments. In addition, the simulation results demonstrate that with increasing normal load, (i) the kinetic energy of the granular fault system increases, (ii) the gouge layer thickness shows a decreasing trend, and (iii) the macroscopic friction coefficient does not experience much change. Analyses of the slip events reveal that, as the normal load increases, more slip events with large kinetic energy release and longer recurrence time occur, and the magnitude of gouge layer thickness decrease also tends to be larger; while the macroscopic friction coefficient drop decreases. The simulations not only reveal the influence of normal loads on the dynamics of sheared granular fault gouge but also demonstrate the capabilities of FDEM for studying stick‐slip dynamic behavior of granular fault systems.
Partitioning of Kinetic Energy in the Arctic Ocean's Beaufort Gyre
Authors: Zhao Mengnan , Timmermans Mary‐Louise , Krishfield Richard , Manucharyan Georgy 
Published: June 2018

AbstractKinetic energy (KE) in the Arctic Ocean's Beaufort Gyre is dominated by the mesoscale eddy field that plays a central role in the transport of freshwater, heat, and biogeochemical tracers. Understanding Beaufort Gyre KE variability sheds light on how this freshwater reservoir responds to wind forcing and sea ice and ocean changes. The evolution and fate of mesoscale eddies relate to energy pathways in the ocean (e.g., the exchange of energy between barotropic and baroclinic modes). Mooring measurements of horizontal velocities in the Beaufort Gyre are analyzed to partition KE into barotropic and baroclinic modes and explore their evolution. We find that a significant fraction of water column KE is in the barotropic and the first two baroclinic modes. We explain this energy partitioning by quantifying the energy transfer coefficients between the vertical modes using the quasi‐geostrophic potential vorticity conservation equations with a specific background stratification observed in the Beaufort Gyre. We find that the quasi‐geostrophic vertical mode interactions uphold the persistence of KE in the first two baroclinic modes, consistent with observations. Our results explain the specific role of halocline structure on KE evolution in the gyre and suggest depressed transfer to the barotropic mode. This limits the capacity for frictional dissipation at the sea floor and suggests that energy dissipation via sea ice‐ocean drag may be prominent.
Vertical Distributions of Soil Organic Carbon and its Influencing Factors Under Different Land Use Types in the Desert Riparian Zone of Downstream Heihe River Basin, China
Authors: Fan Hao , Zhao Wenwu , Daryanto Stefani , Fu Bojie , Wang Shuai , Wang Yaping 
Published: June 2018

AbstractThe amount of soil organic carbon (SOC) reflects the ability of ecosystem to sequester carbon (C). In the desert riparian zone of Heihe River basin, northwest China, that has been the subject of an ecological water conveyance since 2000, studies on SOC under different land use types remain scarce. Yet analyzing soil organic carbon content (SOCC) and its spatial distribution in the area is a key component when studying C cycle in this desert ecosystem. We therefore investigated the vertical distribution of SOC and its influencing factors using field study, and we found significant differences among different land use types and soil depths. The average SOCC and soil organic carbon density in the 0–100 cm soil layers were 23.31 g kg−1 and 6.08 kg m−2, respectively. SOCC and soil organic carbon density decreased in the following order: grassland (5.73 g kg−1) > forestland (5.03 g kg−1) > shrubland (4.79 g kg−1) > cropland (4.28 g kg−1) > Gobi desert (2.10 g kg−1). We also found that vegetation and soil properties jointly affected SOCC in this riparian arid zone, in addition to human disturbance, as indicated by a low stratification ratio in the grassland (1.575) and cropland (1.366). When natural vegetation was transformed into cropland, SOCC decreased with the removal of plant biomass and the increase of wind erosion. Consequently, conservation agricultural practices that consider preservation of soil organic matter (e.g., no‐tillage and intercropping with deep‐rooted leguminous perennial plants) should be introduced in order to prevent further degradation.
Initiation of Streamers Due to Hydrometeor Collisions in Thunderclouds
Authors: Cai Qiheng , Jánský Jaroslav , Pasko Victor P. 
Published: June 2018

AbstractIn order to initiate streamers and leaders under thunderstorm conditions the electric field should reach values higher than the critical breakdown field Ek (i.e., ∼30 kV·cm−1·atm−1). However, the maximum electric field in thunderstorms measured by balloons is ∼6–9 kV·cm−1·atm−1. In present work, to achieve the electric field amplification required for streamer initiation, a system of two approaching spherical hydrometeors is investigated. Streamer initiation is determined from a Meek number, describing electron multiplication in fields above Ek. We have found the relationships between radii of particles for successful streamer initiation in the gap between these two particles and also on the outside periphery of the two particle system when the particles are connected by a discharge channel. Furthermore, we estimated the frequency of streamer initiation using three realistic hydrometeor size model distributions available in the literature and found that the scenario of streamer initiation on the outside periphery is only possible for relatively high electric fields ≥0.5Ek at altitudes of 3 and 6 km.
Crop Residue Burning in Northern India: Increasing Threat to Greater India
Authors: Sarkar S. , Singh R. P. , Chauhan A. 
Published: June 2018

AbstractCrop residue burning (CRB) is a recurring problem, during October–November, in the northwestern regions (Punjab, Haryana, and western Uttar Pradesh) of India. The emissions from the CRB source regions spread in all directions through long‐range transport mechanisms, depending upon the meteorological conditions. In recent years, numerous studies have been carried out dealing with the impact of CRB on the air quality of Delhi and surrounding areas, especially in the Indo‐Gangetic Basin (also referred to as Indo‐Gangetic Plain). In this paper, we present detailed analysis using both satellite‐ and ground‐based sources, which show an increasing impact of CRB over the eastern parts of the Indo‐Gangetic Basin and also over parts of central and southern India. The increasing trends of finer black carbon particles and greenhouse gases have accelerated since the year 2010 onward, which is confirmed by the observation of different wavelength dependent aerosol properties. Our study shows an increased risk to ambient air quality and an increased spatiotemporal extent of pollutants in recent years, from CRB, which could be a severe health threat to the population of these regions.
Development of Multivariable Dynamic System Response Curve Method for Real‐Time Flood Forecasting Correction
Authors: Sun Y. , Bao W. , Jiang P. , Ji X. , Gao S. , Xu Y. , Zhang Q. , Si W. 
Published: June 2018

AbstractError correction method is widely used to improve the performance of flood forecasting. The Dynamic System Response Curve method (DSRC) has been proposed as an error correction method to improve the performance of hydrological modeling. One of the critical problems is the unstable performance caused by the ill‐posed property of the model structure and the inability of estimating multiple variables. To address this problem, the original structure of DSRC was modified to enable the capability of estimating multiple variables. Using the variable forgetting factor recursive least squares algorithm (VFF‐RLS), we proposed an improved version of DSRC (VFF‐RLS‐MDSRC). The proposed method was tested in a synthetic case to examine the ability to correct state variables of a hydrological model. In addition, it was compared with the autoregressive technique in a real case study to evaluate the effects on the improvement of model performance. The results of the synthetic study indicate that the proposed method can significantly improve the performance of both the model output and the state variables. The results of the real case study indicate that the performance obtained by the proposed method tends to have a slower decline trend when increasing the lead time compared with autoregressive technique.
Inverse Modeling of Hydrologic Systems with Adaptive Multifidelity Markov Chain Monte Carlo Simulations
Authors: Zhang Jiangjiang , Man Jun , Lin Guang , Wu Laosheng , Zeng Lingzao 
Published: June 2018

AbstractMarkov chain Monte Carlo (MCMC) simulation methods are widely used to assess parametric uncertainties of hydrologic models conditioned on measurements of observable state variables. However, when the model is CPU‐intensive and high dimensional, the computational cost of MCMC simulation will be prohibitive. In this situation, a CPU‐efficient while less accurate low‐fidelity model (e.g., a numerical model with a coarser discretization or a data‐driven surrogate) is usually adopted. Nowadays, multifidelity simulation methods that can take advantage of both the efficiency of the low‐fidelity model and the accuracy of the high‐fidelity model are gaining popularity. In the MCMC simulation, as the posterior distribution of the unknown model parameters is the region of interest, it is wise to distribute most of the computational budget (i.e., the high‐fidelity model evaluations) therein. Based on this idea, in this paper we propose an adaptive multifidelity MCMC algorithm for efficient inverse modeling of hydrologic systems. In this method, we evaluate the high‐fidelity model mainly in the posterior region through iteratively running MCMC based on a Gaussian process system that is adaptively constructed with multifidelity simulation. The error of the Gaussian process system is rigorously considered in the MCMC simulation and gradually reduced to a negligible level in the posterior region. Thus, the proposed method can obtain an accurate estimate of the posterior distribution with a small number of the high‐fidelity model evaluations. The performance of the proposed method is demonstrated by three numerical case studies in inverse modeling of hydrologic systems.
A nanomedicine approach enables co-delivery of cyclosporin A and gefitinib to potentiate the therapeutic efficacy in drug-resistant lung cancer
Authors: Han Weidong , Shi Linlin , Ren Lulu , Zhou Liqian , Li Tongyu , Qiao Yiting , Wang Hangxiang 
Published: June 2018

AbstractDrug resistance, accounting for therapeutic failure in the clinic, remains a major challenge to effectively manage cancer. Cyclosporin A (CsA) can reverse multidrug resistance (MDR), especially resistance to epidermal growth factor receptor tyrosine kinase inhibitors. However, the application of both drugs in cancer therapies is hampered by their poor aqueous solubility and low bioavailability due to oral administration. CsA augments the potency of gefitinib (Gef) in both Gef-sensitive and Gef-resistant cell lines. Here, we show that the simultaneous encapsulation of CsA and Gef within polyethylene glycol-block-poly(D, L-lactic acid) (PEG-PLA) produced a stable and systemically injectable nanomedicine, which exhibited a sub-50-nm diameter and spherical structures. Impressively, the co-delivery of therapeutics via single nanoparticles (NPs) outperformed the oral administration of the free drug combination at suppressing tumor growth. Furthermore, in vivo results indicated that CsA formulated in NPs sensitized Gef-resistant cells and Gef-resistant tumors to Gef treatment by inactivating the STAT3/Bcl-2 signaling pathway. Collectively, our nanomedicine approach not only provides an alternative administration route for the drugs of choice but also effectively reverses MDR, facilitating the development of effective therapeutic modalities for cancer.