bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clause-initial AND usage in a cross-sectional and longitudinal corpus of school-age children's narratives
Authors: KALLAY Jeffrey E. , REDFORD Melissa A. 
Published: April 2020

AbstractYoung children adopt an event-chaining strategy when storytelling, frequently linking clauses withand. The current study tested whether age-related changes in clause-initialandusage might index narrative structure development in the Eugene Children's Story Corpus (ECSC), which includes 180 structured spontaneous narratives elicited yearly for three years from 60 children, aged five to seven at study onset. The narratives were segmented into clauses to quantify clause-initialandusage. Adult judgments of narrative coherence and cohesiveness were elicited as measures of narrative structure. Mean length of utterance (MLU) and clause (MLC) were used as measures of language complexity. Results indicated developmental increases in all measures, but onlyand-connected dependent clause usage increased with cross-sectional and longitudinal age. Only MLC predicted the relative frequency of clause-initialandregardless of children's age. These results suggest children's frequent use ofandto connect events reflects immature language; its association with flat narrative structure is likely epiphenomenal.
Association of biomarker S100B and cerebral oximetry with	neurological changes during carotid endarterectomy performed in awake	patients
Authors: Makovec Matej , Kerin Klemen , Skitek Milan , Jerin Aleš , Klokočovnik Tomislav 
Published: April 2020

Summary. Background: This study attempted to correlate neurological symptoms in awake patients undergoing carotid endarterectomy (CEA) under local anaesthesia (LA) with serum concentration of S100B protein and measurement of cerebral oximetry with near-infrared spectroscopy (NIRS). Patients and methods: A total of 64 consecutive CEAs in 60 patients operated under LA during an 18-month period were prospectively evaluated. A cerebral oximeter was used to measure cerebral oxygen saturation (rSO2) before and after cross-clamping along with serum concentration of the S100B protein. Selective shunting was performed when neurological changes occurred, regardless of NIRS. Neurological deterioration occurred (neurological symptoms group) in 7 (10.9 %) operations. In 57 (89.1 %) operations, the patients were neurologically stable (no neurological symptoms group). Results: The neurological symptoms that occurred after clamping correlated with an increase in the serum level of S100B ( P = .040). The cut-off of 22.5 % of S100B increase was determined to be optimal for identifying patients with neurological symptoms. There was no correlation between rSO2 decline and neurological symptoms ( P = .675). Two (3.1 %) perioperative strokes occurred. Conclusions: We found a correlation between neurological symptoms and serum S100B protein increase. However, because of the long evaluation time of serum S100B, this monitoring technique cannot be performed during CEA.
The Role of Seismic and Slow Slip Events in Triggering the 2018 M7.1 Anchorage Earthquake in the Southcentral Alaska Subduction Zone
Authors: Segou M. , Parsons T. 
Published: April 2020

AbstractThe M7.1 2018 Anchorage earthquake occurred in the bending part of the subducting North Pacific plate near the geometrical barrier formed by the underthrusting Yakutat terrane. We calculate the triggering potential related with stress redistribution from deformation sources including the M9.2 1964 earthquake coseismic slip, postseismic deformation, slip from regional M > 5 earthquakes, and the cumulative slip of previously detected slow slip events over the past 55 years. We investigate the deeper shallow depth (20–60 km) seismicity response to these perturbations using an epidemic type aftershock sequence model to describe earthquake‐to‐earthquake interactions. The statistical forecast captures the triggered seismicity during the 1983 M6+ aftershocks in Columbia Bay but performs poorly during the slow slip event period between 1992.0 and 2004.8 that presents a statistically significant rate change (β, Z > 2; M < 4.0). We find that stress effects from the 1964 postseismic source and the 12‐year‐long slow slip event (~M7.8) contribute to the 2018 Anchorage earthquake occurrence and that slow slip events modulate the deeper shallow depth seismicity patterns in the region.
Analysis of Iron Sources in Antarctic Continental Shelf Waters
Authors: Dinniman Michael S. , St‐Laurent Pierre , Arrigo Kevin R. , Hofmann Eileen E. , van Dijken Gert L. 
Published: April 2020

AbstractPrevious studies showed that satellite‐derived estimates of chlorophyll a in coastal polynyas over the Antarctic continental shelf are correlated with the basal melt rate of adjacent ice shelves. A 5‐km resolution ocean/sea ice/ice shelf model of the Southern Ocean is used to examine mechanisms that supply the limiting micronutrient iron to Antarctic continental shelf surface waters. Four sources of dissolved iron are simulated with independent tracers, assumptions about the source iron concentration for each tracer, and an idealized summer biological uptake. Iron from ice shelf melt provides about 6% of the total dissolved iron in surface waters. The contribution from deep sources of iron on the shelf (sediments and Circumpolar Deep Water) is much larger at 71%. The relative contribution of dissolved iron supply from basal melt driven overturning circulation within ice shelf cavities is heterogeneous around Antarctica, but at some locations, such as the Amundsen Sea, it is the primary mechanism for transporting deep dissolved iron to the surface. Correlations between satellite chlorophyll a in coastal polynyas around Antarctica and simulated dissolved iron confirm the previous suggestion that productivity of the polynyas is linked to the basal melt of adjacent ice shelves. This correlation is the result of upward advection or mixing of iron‐rich deep waters due to circulation changes driven by ice shelf melt, rather than a direct influence of iron released from melting ice shelves. This dependence highlights the potential vulnerability of coastal Antarctic ecosystems to changes in ice shelf basal melt rates.
Seasonal Variations of the North Equatorial Current Across the Pacific Ocean
Authors: Liu Xueqi , Zhou Hui 
Published: April 2020

AbstractThe seasonal variations of North Equatorial Current (NEC) axis (YCM), intensity (INT), and transport across the Pacific basin are investigated based on altimetry data, Argo data, and ocean reanalysis data. In the western Pacific (WP), the NEC shifts southward/northward when it is intensified/weakened in the first/latter half of the year. However, in the interior Pacific (IP), the INT shows antiphase fluctuations with that in the WP with obvious westward propagations of the meridional shift of theYCM. In the eastern Pacific (EP), the phase relationship between the YCM and INT is opposite to that in the WP with the strengthening/weakening of the NEC being accompanied by a northward/southward shift of its axis. Different locations of the NEC seasonal thermocline departure maxima/minima in the WP, IP, and EP contribute to its distinct seasonal variations in these three basins. One of the new findings is that the seasonal shallowest thermocline generally corresponds to its largest meridional slope in the IP and EP, hence favoring the intensification of the NEC in these two basins, but not the case in the WP. Model experiments by blocking the baroclinic Rossby wave propagations and Ekman pumpings in different basins suggest that the seasonal variations of the NEC in the WP and EP are mainly controlled by the Ekman pumping, while those in the IP are controlled by the joint effect of the local Ekman pumping and the Rossby waves. The Sverdrup theory tends to overestimate the NEC's mean transport.
Atlantic Meridional Overturning Circulation and δ13C Variability During the Last Interglacial
Authors: Kessler A. , Bouttes N. , Roche D. M. , Ninnemann U. S. , Galaasen E. V. , Tjiputra J. 
Published: April 2020

AbstractThe Atlantic Meridional Overturning Circulation (AMOC) is thought to be relatively vigorous and stable during Interglacial periods on multimillennial (equilibrium) timescales. However, recent proxy (δ13C benthic) reconstructions suggest that higher frequency variability in deep water circulation may have been common during some interglacial periods, including the Last Interglacial (LIG, 130–115 ka). The origin of these isotope variations and their implications for past AMOC remain poorly understood. Using iLOVECLIM, an Earth system model of intermediate complexity (EMIC) allowing the computation of
and direct comparison to proxy reconstructions, we perform a transient experiment of the LIG (125–115 ka) forced only by boundary conditions of greenhouse gases and orbital forcings. The model simulates large centennial‐scale variations in the interior
of the North Atlantic similar in timescale and amplitude to changes resolved by high‐resolution reconstructions from the LIG. In the model, these variations are caused by changes in the relative influence of North Atlantic Deep Water (NADW) and southern source water (SSW) and are closely linked to large (∼50%) changes in AMOC strength provoked by saline input and associated deep convection areas south of Greenland. We identify regions within the subpolar North Atlantic with different sensitivity and response to changes in preformed
of NADW and to changes in NADW versus SSW influence, which is useful for proxy record interpretation. This could explain the relatively large δ13C gradient (∼0.4%0) observed at ∼3 km water depth in the subpolar North Atlantic at the inception of the last glacial.
Application of a Modified Spheromak Model to Simulations of Coronal Mass Ejection in the Inner Heliosphere
Authors: Singh Talwinder , Kim Tae K. , Pogorelov Nikolai V. , Arge Charles N. 
Published: April 2020

AbstractThe magnetic fields of interplanetary coronal mass ejections (ICMEs), which originate close to the Sun in the form of a flux rope, determine their geoeffectiveness. Therefore, robust flux rope‐based models of CMEs are required to perform magnetohydrodynamic (MHD) simulations aimed at space weather predictions. We propose a modified spheromak model and demonstrate its applicability to CME simulations. In this model, such properties of a simulated CME as the poloidal and toroidal magnetic fluxes, and the helicity sign can be controlled with a set of input parameters. We propose a robust technique for introducing CMEs with an appropriate speed into a background, MHD solution describing the solar wind in the inner heliosphere. Through a parametric study, we find that the speed of a CME is much more dependent on its poloidal flux than on the toroidal flux. We also show that the CME speed increases with its total energy, giving us control over its initial speed. We further demonstrate the applicability of this model to simulations of CME‐CME collisions. Finally, we use this model to simulate the 12 July 2012 CME and compare the plasma properties at 1 AU with observations. The predicted CME properties agree reasonably with observational data.
Deep Learning Emulation of Subgrid‐Scale Processes in Turbulent Shear Flows
Authors: Pal Anikesh 
Published: April 2020

AbstractDeep neural networks (DNNs) are developed from a data set obtained from the dynamic Smagorinsky model to emulate the subgrid‐scale (SGS) viscosity (νsgs) and diffusivity (κsgs) for turbulent stratified shear flows encountered in the oceans and the atmosphere. These DNNs predict νsgs and κsgs from velocities, strain rates, and density gradients such that the evolution of the kinetic energy budget and density variance budget terms is similar to the corresponding values obtained from the original dynamic Smagorinsky model. These DNNs also compute νsgs and κsgs ∼2–4 times quicker than the dynamic Smagorinsky model resulting in a ∼2–2.5 times acceleration of the entire simulation. This study demonstrates the feasibility of deep learning in emulating the subgrid‐scale (SGS) phenomenon in geophysical flows accurately in a cost‐effective manner. In a broader perspective, deep learning‐based surrogate models can present a promising alternative to the traditional parameterizations of the subgrid‐scale processes in climate models.
Will Climate Change Impact Polar NOxProduced by Energetic Particle Precipitation?
Authors: Maliniemi Ville , Marsh Daniel, R. , Tyssøy Hilde Nesse , Smith‐Johnsen Christine 
Published: April 2020

AbstractEnergetic electron precipitation (EEP) is an important source of polar nitrogen oxides (NOx) in the upper atmosphere. During winter, mesospheric NOxhas a long chemical lifetime and is transported to the stratosphere by the mean meridional circulation. Climate change is expected to accelerate this circulation and therefore increase polar mesospheric descent rates. We investigate the Southern Hemispheric polar NOxdistribution during the 21st century under a variety of future scenarios using simulations of the Whole Atmosphere Community Climate Model (WACCM). We simulate stronger polar mesospheric descent in all future scenarios that increase the atmospheric radiative forcing. Polar NOxin the upper stratosphere is significantly enhanced in two future scenarios with the largest increase in radiative forcing. This indicates that the ozone depleting NOxcycle will become more important in the future, especially if stratospheric chlorine species decline. Thus, EEP‐related atmospheric effects may become more prominent in the future.
Spatiotemporal Evolution of Heat Wave Severity and Coverage Across the United States
Authors: Keellings David , Moradkhani Hamid 
Published: April 2020

AbstractHeat waves have pronounced impacts on human health, ecosystems, and society. Heat waves have become more frequent and intense globally and are likely to intensify further in a warming climate. Across the United States there is a warming trend in average surface temperatures, but concordant increase in heat wave severity appears absent. Limitations in heat waves studies may be responsible for limited detection of a heat wave warming signal. We track daily spatiotemporal evolution of heat waves using geometric concepts and clustering algorithms to investigate how heat manifests on the land surface. We develop a spatial metric combining heat wave frequency, magnitude, duration, and areal extent. We find mixed trends in some individual heat wave characteristics across the United States during 1981–2018. However, exploration of the spatiotemporal evolution of combined heat wave characteristics shows considerable increases during this period and indicates a substantial increase in heat wave hazard across the United States.
Propagation Teepee: A Possible High‐Frequency (15–30 MHz) Remote Lightning Signature Identified by Citizen Scientists
Authors: Fung Shing F. , Typinski David , Flagg Richard , Ashcraft Thomas , Greenman Wes , Higgins Charles , Brown James , Dodd Larry , Reyes Francisco , Sky Jim , Thieman James , Garcia Leonard 
Published: April 2020

AbstractA high‐frequency spectral feature is identified in ground‐based spectrograph data at 15–30 MHz. The feature, likely of terrestrial origin, is often recorded by a group of citizen scientists (the Spectrograph User Group) whose main interest is to observe Jupiter's radio emissions. The feature appears as radio band noise enhancement in which the frequency of enhancement increases and then decreases with time, forming a “triangular spectral feature.” The teepee tent shape leads to its name (TP for short). TPs usually have well‐defined leading and trailing edges. While some TPs occur in isolation, they are often seen in groups, distributed either in time or in apex frequency. While most TPs appear diffuse, close‐up views of a few TPs reveal that they actually consist of discrete bursts, highly suggestive of lightning strokes as possible radiation sources. Here, we investigate the possible generation of TPs by ionospheric reflection of radiation from remote lightning storms.
Internal Variability Dominates Over Externally Forced Ocean Circulation Changes Seen Through CFCs
Authors: Lester J. G. , Lovenduski N. S. , Graven H. D. , Long M. C. , Lindsay K. 
Published: April 2020

AbstractObservations of oceanic transient tracers have indicated that the circulation in the Southern Ocean has changed in recent decades, potentially driven by changes in external climate forcing. Here, we use the CESM Large Ensemble to analyze changes in two oceanic tracers that are affected by ocean circulation: the partial pressure of chlorofluorocarbon‐12 (pCFC12) and the idealized model tracer Ideal Age (IAGE) over the 1991 to 2005 period. The small ensemble mean change in IAGE suggests that there has been very little externally forced change in Southern Ocean circulation over this period, in contrast to strong internal variability. Further, our analysis implies that real‐world observations of changes in pCFC12 may not be a robust way to characterize externally driven changes in Southern Ocean circulation because of the large internal variability in pCFC12 changes exhibited by the individual ensemble members.
Drought Reconstruction Over the Past Two Centuries in Southern Myanmar Using Teak Tree‐Rings: Linkages to the Pacific and Indian Oceans
Authors: Zaw Zaw , Fan Ze‐Xin , Bräuning Achim , Xu Chen‐Xi , Liu Wen‐Jie , Gaire Narayan Prasad , Panthi Shankar , Than Kay Zin 
Published: April 2020

AbstractTo develop a high‐resolution paleoclimate proxy record facilitating adaptation measures on drought impacts, we constructed a regional composite tree‐ring chronology of teak (Tectona grandis) by combining three local site chronologies from southern Myanmar. Our regional tree‐ring record is strongly correlated with the November–April self‐calibrated Palmer drought severity index and enabled us to reconstruct drought variability for the period 1802–2016. The reconstruction explained 46.5% of the actual self‐calibrated Palmer drought severity index variance. Over the past two centuries, we detected one extreme (1812) and six severe drought years (1810, 1811, 1816, 1852, 1887, and 1980). Dry periods coincided with six major famines that occurred in India. Spatial correlation analyses revealed that drought occurrence is linked to broader‐scale atmospheric circulations of the Pacific and Indian Oceans, especially during the positive phase of the El Niño–Southern Oscillation. Our reconstruction provides a useful historical perspective for assessing adaptation measures intent on mitigating future drought impacts in Myanmar.
Assessment of Sea Ice Extent in CMIP6 With Comparison to Observations and CMIP5
Authors: Shu Qi , Wang Qiang , Song Zhenya , Qiao Fangli , Zhao Jiechen , Chu Min , Li Xinfang 
Published: April 2020

AbstractBoth the Arctic and Antarctic sea ice extents (SIEs) from 44 coupled models in the Coupled Model Intercomparison Project Phase 6 (CMIP6) are evaluated by comparing them with observations and CMIP5 results. The CMIP6 multimodel mean can adequately reproduce the seasonal cycles of both the Arctic and Antarctic SIE. The observed Arctic September SIE declining trend (−0.82 ± 0.18 million km2 per decade) between 1979 and 2014 is slightly underestimated in CMIP6 models (−0.70 ± 0.06 million km2 per decade). The observed weak but significant upward trend of the Antarctic SIE is not captured, which was an issue already in the CMIP5 phase. Compared with CMIP5 models, CMIP6 models have lower intermodel spreads in SIE mean values and trends, although their SIE biases are relatively larger. The CMIP6 models did not reproduce the new summer tendencies after 2000, including the faster decline of Arctic SIE and the larger interannual variability in Antarctic SIE.
Decadal Changes of Meridional Eddy Heat Transport in the Subpolar North Atlantic Derived From Satellite and In Situ Observations
Authors: Müller Vasco , Melnichenko Oleg 
Published: April 2020

AbstractThe interannual variability of the meridional eddy heat transport in the North Atlantic is investigated based on the combined use of satellite observations of sea level anomaly (SLA) and sea surface temperature (SST) over the 25 year period from 1993 to 2017. The focus is on 47°N, a latitude close to the boundary between the subpolar and the subtropical gyres. The vertical structure of the eddy heat transport is reconstructed in 10° longitude × 5° latitude boxes from a composite analysis of Argo profile data and observations of mesoscale eddies in altimetric SLA. The transport is surface intensified with almost 95% happening above the pycnocline. It can vary immensely both zonally and vertically, in some cases reversing sign below the pycnocline. The basin‐wide integrated eddy heat transport accounts for around 6% of the total meridional heat transport. During the observed period, the eddy heat transport increased on average by 0.6 TW/yr, accelerating to 1.3 TW/yr after 2005. The observed trends and variations in the eddy heat transport can be related to the large‐scale temperature gradients in the region and in response to the North Atlantic Oscillation. They provide a considerable contribution to the variability of the total oceanic heat transport, suggesting a potentially important forcing mechanism in the ocean component of the climate system.
Submesoscale Eddy and Frontal Instabilities in the Kuroshio Interacting With a Cape South of Taiwan
Authors: Cheng Yu‐Hsin , Chang Ming‐Huei , Ko Dong S. , Jan Sen , Andres Magdalena , Kirincich Anthony , Yang Yiing Jang , Tai Jen‐Hua 
Published: April 2020

AbstractThe processes underlying the strong Kuroshio encountering a cape at the southernmost tip of Taiwan are examined with satellite‐derived chlorophyll and temperature maps, a drifter trajectory, and realistic model simulations. The interaction spurs the formation of submesoscale cyclonic eddies that trap cold and high‐chlorophyll water and the formation of frontal waves between the free stream and the wake flow. An observed train of eddies, which have relative vorticity about one to four times the planetary vorticity (f), is shed from the recirculation that occurs in the immediate lee of the cape as a result of flow separation. These propagate downstream at a speed of 0.5–0.6 m s−1. Farther downstream, the corotation and merging of two or three adjacent eddies are common owing to the topography‐induced slowdown of eddy propagation farther downstream. It is found that the relative vorticity of a corotating system (1.2f) is 70% weaker than that of a single eddy due to the increase of eddy diameter from ~16 to ~33 km, in agreement with Kelvin's circulation theorem. The shedding period of the submesoscale eddies is strongly modulated by either diurnal or semidiurnal tidal flows, which typically reach 0.2–0.5 m s−1, whereas its intrinsic shedding period is insignificant. The frontal waves predominate in the horizontal free shear layer emitted from the cape, as well as a density front. Energetics analysis suggests that the wavy features result primarily from the growth of barotropic instability in the free shear layer, which may play a secondary process in the headland wake.