bluuebunny/crossref_metadata_2025_split huggingface dataset:
Curlometer Technique and Applications
Authors: Dunlop M. W. , Dong X.‐C. , Wang T.‐Y. , Eastwood J. P. , Robert P. , Haaland S. , Yang Y.‐Y. , Escoubet P. , Rong Z.‐J. , Shen C. , Fu H.‐S. , De Keyser J. 
Published: November 2021

AbstractWe review the range of applications and use of the curlometer, initially developed to analyze Cluster multi‐spacecraft magnetic field data; but more recently adapted to other arrays of spacecraft flying in formation, such as MMS small‐scale, 4‐spacecraft configurations; THEMIS close constellations of 3–5 spacecraft, and Swarm 2–3 spacecraft configurations. Although magnetic gradients require knowledge of spacecraft separations and the magnetic field, the structure of the electric current density (for example, its relative spatial scale), and any temporal evolution, limits measurement accuracy. Nevertheless, in many magnetospheric regions the curlometer is reliable (within certain limits), particularly under conditions of time stationarity, or with supporting information on morphology (for example, when the geometry of the large scale structure is expected). A number of large‐scale regions have been covered, such as: the cross‐tail current sheet, ring current, the current layer at the magnetopause and field‐aligned currents. Transient and smaller scale current structures (e.g., reconnected flux tube or dipolarisation fronts) and energy transfer processes. The method is able to provide estimates of single components of the vector current density, even if there are only two or three satellites flying in formation, within the current region, as can be the case when there is a highly irregular spacecraft configuration. The computation of magnetic field gradients and topology in general includes magnetic rotation analysis and various least squares approaches, as well as the curlometer, and indeed the added inclusion of plasma measurements and the extension to larger arrays of spacecraft have recently been considered.
Electrodynamic Contributions to the Hall‐ and Parallel Electric Fields in Collisionless Magnetic Reconnection
Authors: Lu San , Angelopoulos V. , Pritchett P. L. , Nan Jia , Huang Kai , Tao Xin , Artemyev A. V. , Runov A. , Jia Yingdong , Sun Haomin , Kang Ning 
Published: November 2021

AbstractIn collisionless magnetic reconnection, the Hall electric field and the parallel electric field play important roles because they are responsible for acceleration of charged particles, especially electrons. Using particle‐in‐cell simulations, we study electrodynamic nature of the two electric fields in two‐dimensional collisionless reconnection. We find that the Hall electric field is predominantly () electrostatic; its electromagnetic (induced) component is small but nonzero (). The parallel electric field or potential is contributed comparably by its electrostatic and induced components. In the electron inflow region, along the separatrix, and at the X‐line, the electrostatic component of the parallel electric field (or potential) is larger; while in the electron outflow region, the electromagnetic (induced) component is larger. An initial guide field does not change the electrodynamic nature of the Hall electric field but does change that of the parallel electric field. In the guide field case, the parallel electric field is contributed predominantly by the electromagnetic component from the electron inflow region to the X‐line and by the electrostatic component in the electron outflow region.
The Influence of Depth‐Varying Elastic Properties of the Upper Plate on Megathrust Earthquake Rupture Dynamics and Tsunamigenesis
Authors: Prada Manel , Galvez Percy , Ampuero Jean‐Paul , Sallarès Valentí , Sánchez‐Linares Carlos , Macías Jorge , Peter Daniel 
Published: November 2021

AbstractMegathrust earthquakes are strongly influenced by the elastic properties of rocks surrounding the fault. In contrast to friction, these properties can be derived in situ from geophysical measurements along the seismogenic zone. However, they are often overestimated in numerical simulations, particularly in the shallow megathrust. Here we explore the influence that realistic depth‐varying upper‐plate elastic properties along the megathrust have on earthquake rupture dynamics and tsunamigenesis using 3D dynamic rupture and tsunami simulations. We compare results from three subduction zone scenarios with homogeneous and heterogeneous elastic media, and bimaterial fault. Elastic properties in the heterogeneous model follow a realistic depth‐distribution derived from controlled‐source tomography models of subduction zones. We assume the same friction properties for all scenarios. Simulations in the heterogeneous and homogeneous models show that rigidity depth variations explain the depth‐varying behavior of slip, slip rate, frequency content, and rupture time. The depth‐varying behavior of slip, frequency content, and rupture duration quantitatively agree with previous predictions based on worldwide data compilations, explaining the main depth‐dependent traits of tsunami earthquakes and large shallow megathrust earthquakes. Large slip, slow rupture and slip rate amplification in bimaterial simulations are largely controlled by elastic rock properties of the most compliant side of the fault, which in subduction zones is the upper plate. Large shallow slip and trenchward increasing upper‐plate compliance of the heterogeneous model lead to the largest co‐seismic seafloor deformation and tsunami amplitude. This highlights the importance of considering realistic upper‐plate rigidity variations to properly assess the tsunamigenic potential of megathrust earthquakes.
Spatial Patterns in Frictional Behavior of Sediments Along the Kumano Transect in the Nankai Trough
Authors: Okuda Hanaya , Ikari Matt J. , Roesner Alexander , Stanislowski Katja , Hüpers Andre , Yamaguchi Asuka , Kopf Achim J. 
Published: November 2021

AbstractFault slip activity at subduction zones is governed by sediment frictional properties, which in turn are affected by diagenetic processes. To study the spatial patterns in frictional properties across the Nankai Trough, SW Japan, and their relations to fault slip activity, we used sediment samples (10%–59% clay mineral content) along the Kumano transect covering a large spatial range from the inputs via the outer prism to the inner prism, including the deepest sample ever recovered to date. We performed laboratory friction experiments under in situ effective normal stresses and seawater‐saturated conditions. Our results generally demonstrate that the friction coefficient inversely correlates with the clay mineral content. However, the outer prism sediments show higher friction coefficients than sediments from the other locations for a comparable clay mineral content. All samples show velocity‐weakening behavior at low velocities, but the outer prism and the deep inner prism sediments show velocity strengthening at higher velocities. Based on the experimental results combined with a Coulomb wedge model, we propose that the lowest friction coefficient on the décollement occurs beneath the trenchward portion of the outer prism, whereas the minimum friction coefficient of the prism sediment occurs in the landward portion of the outer prism. In addition, the calculated critical nucleation length for slip instability suggests that the décollement beneath the outer prism area is more frictionally unstable than it is beneath the inner prism. This inference is consistent with the spatial distribution of very‐low‐frequency earthquakes and slow slip events along the shallow Nankai Trough.
Wave Regime and Wave‐Current Coupling in an Upwelling–Driven Bay: Seasonal and Inter‐Annual Variability
Authors: Villacieros‐Robineau Nicolás , Gilcoto Miguel , Pardo Paula C. , Barton Eric Desmond 
Published: November 2021

AbstractData from an acoustic Doppler current profiler (ADCP), a wave‐gauge, a met‐ocean buoy and model results provide new insights into the wave regime in a partially sheltered upwelling‐driven bay, the Ría de Vigo (NW Iberia), and the adjacent continental shelf from June 2013 to August 2014. Swell on the NW‐Iberian shelf comes mainly from NW directions, while wind sea comes from the NW under upwelling conditions, and from the SW under downwelling conditions. As the ria is protected from the NW and exposed to the SW, swell is almost always attenuated when entering the bay, and wave height inside the ria depends mostly on shelf wind sea variability. During the upwelling season, swell and wind sea barely enter the ria and wave heights inside the ria are small (0.21 m). During the downwelling season, shelf wind sea directly enters the ria, contributing more to the total wave height which achieves its maximum values (0.46 m). There is a cumulative action of wave and currents (wave current coupling, WCC) that is stronger during the downwelling season. The WCC entails an increase in the seabed energy which could reinforce bottom remineralization. The inter‐annual variability (2009–2016) of winter wave height and WCC in the ria is associated with the combined role played by the North Atlantic Oscillation (NAO) and West Europe Pressure Anomaly (WEPA) indices. The highest waves and strongest WCC occur during the coincidence of negative NAO and positive WEPA phases and can have potentially relevant repercussions on the ecosystem services of the ria.
Reconstruction of Three‐Dimensional Temperature and Salinity Fields From Satellite Observations
Authors: Meng Lingsheng , Yan Chi , Zhuang Wei , Zhang Weiwei , Yan Xiao‐Hai 
Published: November 2021

AbstractObservation of the ocean is crucial to the studies of ocean dynamics, climate change, and biogeochemical cycle. However, current oceanic observations are patently insufficient, because the in situ observations are of difficulty and high cost while the satellite remote‐sensed measurements are mainly the sea surface data. To make up for the shortage of ocean interior data and make full use of the abundant satellite data, here we develop a data‐driven deep learning model to estimate ocean subsurface and interior variables from satellite‐observed sea surface data. Exclusively and simply using satellite data, three‐dimensional ocean temperature and salinity fields are successfully reconstructed, which are at 26 level depths from 0 to 2,000 m. We further design a scheme to increase the horizontal resolution from 1° to 1/4°, which is higher than the Argo gridded data. Estimations from our model are accurate, reliable, and stable for a wide range of research areas and periods. Dynamic height fields that are derived from the estimated temperature and salinity, as well as the associated ocean geostrophic flows, are also calculated and analyzed, which indicates the potentials of our model for reconstructing the ocean circulation fields as well. This study enriches oceanic observations with respect to vertical dimension and horizontal resolution, which can largely make up for the paucity of the subsurface and deep ocean observation, both before and during Argo era. This work also provides some new foundations for and insights into geoscience and climate change fields.
Observed Variability of Bottom‐Trapped Topographic Rossby Waves Along the Slope of the Northern South China Sea
Authors: Wang Jinghong , Shu Yeqiang , Wang Dongxiao , Xie Qiang , Wang Qiang , Chen Ju , Zu Tingting , Liu Danian , He Yunkai 
Published: November 2021

AbstractStrong deep‐current variabilities with periods of 8–25, 16–40, and 30–80 days observed in the northern South China Sea (NSCS) are interpreted as topographic Rossby waves (TRWs) based on the moored observations from July 25, 2017 to August 13, 2018. The TRWs present significantly spatial distribution in the frequency and intensity, which are largely controlled by the mesoscale perturbations in the upper layer. Longer‐period (30–80‐day) TRWs observed to the west of the Dongsha Islands were excited by locally enhanced perturbations with the periods of 30–80 days in the upper ocean. The bottom currents in the periods of 8–25 days observed on the slope of the northeastern South China Sea (NESCS) were influenced by upper‐layer mesoscale perturbations on their northeastern side through TRW propagation in the deep ocean in addition to local processes. In the Luzon Strait, deep currents with the periods of 16–40 days were associated with locally strong perturbations in the upper layer. The distribution of the bottom current variability was closely related to the spatial variability of the upper‐layer fluctuations. The 8‐25‐day bandpass‐filtered surface eddy kinetic energy (EKE) was overall maximal in the Luzon Strait and weakened westward to the east side of the Dongsha Islands, which explained why TRWs with the periods of 8–25 days were more energetic in the Luzon Strait. The surface fluctuations with the periods of 30–80 days were dominant in the west of the Dongsha Islands, and triggered the strong TRWs with the frequency band.
Large‐Scale Tectonic Forcing of the African Landscape
Authors: O’Malley C. P. B. , White N. J. , Stephenson S. N. , Roberts G. G. 
Published: November 2021

AbstractSuccessful inverse modeling of observed longitudinal river profiles suggests that fluvial landscapes are responsive to continent‐wide tectonic forcing. However, inversion algorithms make simplifying assumptions about landscape erodibility and drainage planform stability that require careful justification. For example, precipitation rate and drainage catchment area are usually assumed to be invariant. Here, we exploit a closed‐loop modeling strategy by inverting drainage networks generated by dynamic landscape simulations in order to investigate the validity of these assumptions. First, we invert 4,018 African river profiles to determine an uplift history that is independently calibrated, and subsequently validated, using separate suites of geologic observations. Second, we use this tectonic forcing to drive landscape simulations that permit divide migration, interfluvial erosion and changes in catchment size. These simulations reproduce large‐scale features of the African landscape, including growth of deltaic deposits. Third, the influence of variable precipitation is investigated by carrying out a series of increasingly severe tests. Inverse modeling of drainage inventories extracted from simulated landscapes can largely recover tectonic forcing. Our closed‐loop modeling strategy suggests that large‐scale tectonic forcing plays the primary role in landscape evolution. One corollary of the integrative solution of the stream‐power equation is that precipitation rate becomes influential only if it varies on time scales longer than ∼1 Ma. We conclude that calibrated inverse modeling of river profiles is a fruitful method for investigating landscape evolution and for testing source‐to‐sink models.
Assessing the Trustworthiness of Crowdsourced Rainfall Networks: A Reputation System Approach
Authors: Chen Alexander B. , Behl Madhur , Goodall Jonathan L. 
Published: November 2021

AbstractHigh resolution and accurate rainfall information is essential to modeling and predicting hydrological processes. Crowdsourced personal weather stations (PWSs) have become increasingly popular in recent years and can provide dense spatial and temporal resolution in rainfall estimates. However, their usefulness could be limited due to less trust in crowdsourced data compared to traditional data sources. Using crowdsourced PWSs data without a robust evaluation of its trustworthiness can result in inaccurate rainfall estimates as PWSs are installed and maintained by non‐experts. In this study, we advance the Reputation System for Crowdsourced Rainfall Networks (RSCRN) to bridge this trust gap by assigning dynamic trust scores to PWSs. Based on rainfall data collected from 18 PWSs in two dense clusters in Houston, Texas, USA as a case study, we found that using RSCRN‐derived trust scores can increase the accuracy of 15‐min PWS rainfall estimates when compared to rainfall observations recorded at the city's high‐fidelity rainfall stations. Overall, RSCRN rainfall estimates improved for 77% (48 out of 62) of the analyzed storm events, with a median root‐mean‐square error (RMSE) improvement of 27.3%. Compared to an existing PWS quality control method, results showed that RSCRN improved rainfall estimates for 71% of the storm events (44 out of 62), with a median RMSE improvement of 18.7%. Using RSCRN‐derived trust scores can make the rapidly growing network of PWSs a more useful resource for hydrologic applications, greatly improving knowledge of rainfall patterns in areas with dense PWSs.
Estimation of Evapotranspiration Rates and Root Water Uptake Profiles From Soil Moisture Sensor Array Data
Authors: Li Weiyu , Wainwright Haruko M. , Yan Qina , Zhou Haiyan , Dafflon Baptiste , Wu Yuxin , Versteeg Roelof , Tartakovsky Daniel M. 
Published: November 2021

AbstractEvapotranspiration is arguably the least quantified component of the hydrologic cycle. We propose two complementary strategies for estimation of evapotranspiration rates and root water uptake profiles from soil‐moisture sensor‐array data. One is our implementation of ensemble Kalman filter (EnKF); it treats the evapotranspiration sink term in the Richards equation, rather than soil moisture, as the observable to update. The other is a maximum likelihood estimator (MLE) applied to the same observable; it is supplemented with the Fisher information matrix to quantify uncertainty in its predictions. We use numerical experiments to demonstrate the accuracy and computational efficiency of these techniques. We found our EnKF implementation to be two orders of magnitude faster than either the standard EnKF or MLE, and our MLE procedure to require an order of magnitude fewer iterations to converge than its counterpart applied to soil moisture. These findings render our methodologies a viable and practical tool for estimation of the root water uptake profiles and evaporation rates, with the MLE technique to be used when the prior knowledge about evapotranspiration at the site is elusive.
Introducing gradient severe shot peening as a novel mechanical surface treatment
Authors: Maleki Erfan , Bagherifard Sara , Unal Okan , Bandini Michele , Farrahi Gholam Hossein , Guagliano Mario 
Published: November 2021

AbstractShot peening is widely used for improving mechanical properties especially fatigue behavior of metallic components by inducing surface hardening, compressive residual stresses and surface grain refinement. In air blast shot peening, projection pressure and surface coverage (an index of peening duration) have been considered as major controlling process parameters; the combination of these parameters plays a critical role in the beneficial effects of shot peening. Generally in severe shot peening aimed at obtaining surface grain refinement, constant values of pressure are considered with different peening durations. Considering very high peening duration, however, the phenomenon of over shot peening, which can be identified with the formation of surface defects could occur. The present study introduces a novel shot peening treatment, here called gradient severe shot peening (GSSP) that instead of using constant projection pressure, implements gradually increasing or decreasing pressures. The gradual increase of the projection pressure acts as a pre-hardening stage for the following higher projection pressure boosting the potential of the material to tolerate the sequential impacts and thus become less prone to the formation of surface defects. The results of the experiments indicate significant fatigue life improvement obtained for GSSP treated specimens compared to the standard treatment with constant pressure. GSSP avoids the detrimental effects of over-peening, while maintaining the beneficial effects of surface nano-crystallization, surface hardening and compressive residual stresses. The notable difference in fatigue strength enhancement for GSSP treated material can be also attributed to the modulated surface morphology with lower surface roughness compared to a standard shot peening treatment with the same exposure time.
The definition of low wall shear stress and its effect on plaque progression estimation in human coronary arteries
Authors: Hartman Eline M. J. , De Nisco Giuseppe , Gijsen Frank J. H. , Korteland Suze-Anne , van der Steen Anton F. W. , Daemen Joost , Wentzel Jolanda J. 
Published: November 2021

AbstractWall shear stress (WSS), the frictional force of the blood on the vessel wall, plays a crucial role in atherosclerotic plaque development. Low WSS has been associated with plaque growth, however previous research used different approaches to define low WSS to investigate its effect on plaque progression. In this study, we used four methodologies to allocate low, mid and high WSS in one dataset of human coronary arteries and investigated the predictive power of low WSS for plaque progression. Coronary reconstructions were based on multimodality imaging, using intravascular ultrasound and CT-imaging. Vessel-specific flow was measured using Doppler wire and computational fluid dynamics was performed to calculate WSS. The absolute WSS range varied greatly between the coronary arteries. On the population level, the established pattern of most plaque progression at low WSS was apparent in all methodologies defining the WSS categories. However, for the individual patient, when using measured flow to determine WSS, the absolute WSS values range so widely, that the use of absolute thresholds to determine low WSS was not appropriate to identify regions at high risk for plaque progression.
Patterns of exposure to SARS-CoV-2 carriers manifest multiscale association between urban landscape morphology and human activity
Authors: Cotlier Gabriel I. , Lehahn Yoav , Chelouche Doron 
Published: November 2021

AbstractThe outbreak of the Coronavirus disease 2019 (COVID-19), and the drastic measures taken to mitigate its spread through imposed social distancing, have brought forward the need to better understand the underlying factors controlling spatial distribution of human activities promoting disease transmission. Focusing on results from 17,250 epidemiological investigations performed during early stages of the pandemic outbreak in Israel, we show that the distribution of carriers of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which causes COVID-19, is spatially correlated with two satellite-derived surface metrics: night light intensity and landscape patchiness, the latter being a measure to the urban landscape’s scale-dependent spatial heterogeneity. We find that exposure to SARS-CoV-2 carriers was significantly more likely to occur in “patchy” parts of the city, where the urban landscape is characterized by high levels of spatial heterogeneity at relatively small, tens of meters scales. We suggest that this spatial association reflects a scale-dependent constraint imposed by the city’s morphology on the cumulative behavior of the people inhabiting it. The presented results shed light on the complex interrelationships between humans and the urban landscape in which they live and interact, and open new avenues for implementation of multi-satellite data in large scale modeling of phenomena centered in urban environments.