bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deciphering Patterns and Drivers of Heat and Carbon Storage in the Southern Ocean
Authors: Chen Haidi , Morrison Adele K. , Dufour Carolina O. , Sarmiento Jorge L. 
Published: March 2019

AbstractThe storage of anomalous heat and carbon in the Southern Ocean in response to increasing greenhouse gases greatly mitigates atmospheric warming and exerts a large impact on the marine ecosystem. However, the mechanisms driving the ocean storage patterns are uncertain. Here using recent hydrographic observations, we compare for the first time the spatial patterns of heat and carbon storage, which show substantial differences in the Southern Ocean, in contrast with the conventional view of simple passive subduction into the thermocline. Using an eddy‐rich global climate model, we demonstrate that redistribution of the preindustrial temperature field is the dominant control on the heat storage pattern, whereas carbon storage largely results from passive transport of anthropogenic carbon uptake at the surface. Lastly, this study highlights the importance of realistic representation of wind and surface buoyancy flux in climate models to improve future projection of circulation change and thus heat and carbon storage.
The 2015 Gorkha Earthquake: Earthquake Reflection Imaging of the Source Fault and Connecting Seismic Structure With Fault Slip Behavior
Authors: Kurashimo Eiji , Sato Hiroshi , Sakai Shin'ichi , Hirata Naoshi , Gajurel Ananta Prasad , Adhikari Danda Pani , Subedi Krishna Prasad , Yagi Hiroshi , Upreti Bishal Nath 
Published: March 2019

AbstractA seismic array observation across the central focal area of the 2015 Gorkha earthquake was conducted to investigate aftershock distribution and crustal structure. Most aftershocks near Kathmandu were located above the Main Himalayan Thrust (MHT). Earthquake reflection imaging revealed the geometry of the MHT, which lies at ~10‐km depth at 75 km away from the Main Frontal Thrust. We found three areas of seismic velocity variability around the MHT above 15 km depth: (1) a high‐Vp zone where the MHT changes its dip angle from 5° to 13°, coinciding with a local maximum in coseismic slip, (2) a low‐Vp zone showing less coseismic slip, and (3) a high‐Vp zone where coseismic slip decreased further but afterslip occurred. These differences in slip behavior may indicate changes in frictional properties on the fault, which are reflected in the heterogeneity of the velocity structure.
How Well Can We Estimate Pedersen Conductance From the THEMIS White‐Light All‐Sky Cameras?
Authors: Lam M. M. , Freeman M. P. , Jackman C. M. , Rae I. J. , Kalmoni N. M. E. , Sandhu J. K. , Forsyth C. 
Published: March 2019

AbstractWe show that a white‐light all‐sky imager can estimate Pedersen conductance with an uncertainty of 3 mho or 40%. Using a series of case studies over a wide range of geomagnetic activity, we compare estimates of Pedersen conductance from the backscatter spectrum of the Poker Flat Incoherent Scatter Radar with auroral intensities. We limit this comparison to an area bounding the radar measurements and within a limited area close to (but off) imager zenith. We confirm a linear relationship between conductance and the square root of auroral intensity predicted from a simple theoretical approximation. Hence, we extend a previous empirical result found for green‐line emissions to the case of white‐light off‐zenith emissions. The difference between the radar conductance and the best‐fit relationship has a mean of −0.76 ± 4.8 mho and a relative mean difference of 21% ± 78%. The uncertainties are reduced to −0.72 ± 3.3 mho and 0% ± 40% by averaging conductance over 10 min, which we attribute to the time that auroral features take to move across the imager field being greater than the 1‐min resolution of the radar data. Our results demonstrate and calibrate the use of Time History of Events and Macroscale Interactions during Substorms all‐sky imagers for estimating Pedersen conductance. This technique allows the extension of estimates of Pedersen conductance from Incoherent Scatter Radars to derive continental‐scale estimates on scales of ~1–10 min and ~100 km2. It thus complements estimates from low‐altitude satellites, satellite auroral imagers, and ground‐based magnetometers.
Outer Van Allen Radiation Belt Response to Interacting Interplanetary Coronal Mass Ejections
Authors: Kilpua E. K. J. , Turner D. L. , Jaynes A. N. , Hietala H. , Koskinen H. E. J. , Osmane A. , Palmroth M. , Pulkkinen T. I. , Vainio R. , Baker D. , Claudepierre S. G. 
Published: March 2019

AbstractWe study the response of the outer Van Allen radiation belt during an intense magnetic storm on 15–22 February 2014. Four interplanetary coronal mass ejections (ICMEs) arrived at Earth, of which the three last ones were interacting. Using data from the Van Allen Probes, we report the first detailed investigation of electron fluxes from source (tens of kiloelectron volts) to core (megaelectron volts) energies and possible loss and acceleration mechanisms as a response to substructures (shock, sheath and ejecta, and regions of shock‐compressed ejecta) in multiple interacting ICMEs. After an initial enhancement induced by a shock compression of the magnetosphere, core fluxes strongly depleted and stayed low for 4 days. This sustained depletion can be related to a sequence of ICME substructures and their conditions that influenced the Earth's magnetosphere. In particular, the main depletions occurred during a high‐dynamic pressure sheath and shock‐compressed southward ejecta fields. These structures compressed/eroded the magnetopause close to geostationary orbit and induced intense and diverse wave activity in the inner magnetosphere (ULF Pc5, electromagnetic ion cyclotron, and hiss) facilitating both effective magnetopause shadowing and precipitation losses. Seed and source electrons in turn experienced stronger variations throughout the studied interval. The core fluxes recovered during the last ICME that made a glancing blow to Earth. This period was characterized by a concurrent lack of losses and sustained acceleration by chorus and Pc5 waves. Our study highlights that the seemingly complex behavior of the outer belt during interacting ICMEs can be understood by the knowledge of electron dynamics during different substructures.
Fluid Pressure‐Triggered Foreshock Sequence of the 2008 Mogul Earthquake Sequence: Insights From Stress Inversion and Numerical Modeling
Authors: Jansen G. , Ruhl C. J. , Miller S. A. 
Published: March 2019

AbstractIn Mogul west of Reno, Nevada, USA, in late February 2008 an earthquake sequence occurred that culminated in a magnitude 4.9 mainshock after a foreshock‐rich period lasting approximately 2 months on previously unidentified fault structures. In this article, we show that the foreshock sequence may have been driven by a fluid pressure intrusion. We use 1,082 previously calculated earthquake focal mechanisms to infer the local stress field as well as 1,408 relocated foreshock events to determine the required excess fluid pressure field in the source region of the Mogul earthquake sequence to trigger these events. A model of nonlinear pore pressure diffusion is used to model the fluid flow in a highly fractured subsurface. We find a strong correlation between high fluid pressure fronts and foreshock hypocenters, suggesting a natural fluid‐driven earthquake sequence.
Capillary Pressure Curve Determination Based on a 2‐D Cross‐Section Analysis Via Fractal Geometry: A Bridge Between 2‐D and 3‐D Pore Structure of Porous Media
Authors: Chen Xiaojun , Yao Guangqing , Luo Chengfei , Jiang Ping , Cai Jianchao , Zhou Kun , Herrero‐Bervera E. 
Published: March 2019

AbstractPore structure is a crucial attribute in characterizing fluid flow through porous media. However, direct experimental measurements or numerical reconstructions are commonly expensive and not environmentally friendly, with great uncertainty caused by the complex nature of porous media. In this study, we demonstrate that one special bridge function, which is a function of the apparent length and tortuosity fractal dimension, can characterize the relationship of pore structures between two dimensions (2‐D) and three dimensions (3‐D), and it can serve as a conversion bridge of the radius to determine the capillary pressure curve (CPC). We compare estimations by the proposed method with experimental results obtained by mercury intrusion porosimetry in six typical natural sandstones with varying porosities and permeabilities. The result shows that cross sections of the global pore structure, such as thin section, electronic probe, and microcomputed tomography slices, give a reliable estimation of the CPC using the bridge function in porous media with a medium porosity. However, in unconventional porous media with a relatively low porosity (~10%) or extra high porosity (~30%), due to the empirical nature of the equation widely used to calculate the tortuosity fractal dimension, the necessary modification is necessary to obtain the CPC when applying the bridge function in such porous media. This insight can significantly simplify the procedure for obtaining the petrophysical properties of a porous medium, which may shed light on the inherent differences and correlations between the 2‐D and 3‐D pore structures of porous media.
Fluid Distribution in the Central Andes Subduction Zone Imaged With Magnetotellurics
Authors: Araya Vargas J. , Meqbel N. M. , Ritter O. , Brasse H. , Weckmann U. , Yáñez G. , Godoy B. 
Published: March 2019

AbstractWe present a model of the electrical resistivity structure of the lithosphere in the Central Andes between 20° and 24°S from 3‐D inversion of 56 long‐period magnetotelluric sites. Our model shows a complex resistivity structure with significant variability parallel and perpendicular to the trench direction. The continental forearc is characterized mainly by high electrical resistivity (>1,000 Ωm), suggesting overall low volumes of fluids. However, low resistivity zones (LRZs, <5 Ωm) were found in the continental forearc below areas where major trench‐parallel faults systems intersect NW‐SE transverse faults. Forearc LRZs indicate circulation and accumulation of fluids in highly permeable fault zones. The continental crust along the arc shows three distinctive resistivity domains, which coincide with segmentation in the distribution of volcanoes. The northern domain (20°–20.5°S) is characterized by resistivities >1,000 Ωm and the absence of active volcanism, suggesting the presence of a low‐permeability block in the continental crust. The central domain (20.5°–23°S) exhibits a number of LRZs at varying depths, indicating different levels of a magmatic plumbing system. The southern domain (23°–24°S) is characterized by resistivities >1,000 Ωm, suggesting the absence of large magma reservoirs below the volcanic chain at crustal depths. Magma reservoirs located below the base of the crust or in the backarc may fed active volcanism in the southern domain. In the subcontinental mantle, the model exhibits LRZs in the forearc mantle wedge and above clusters of intermediate‐depth seismicity, likely related to fluids produced by serpentinization of the mantle and eclogitization of the slab, respectively.
Constraining a Historical Black Carbon Emission Inventory of the United States for 1960–2000
Authors: Sun T. , Liu L. , Flanner M. G. , Kirchstetter T. W. , Jiao C. , Preble C. V. , Chang W. L. , Bond T. C. 
Published: March 2019

AbstractWe present an observationally constrained United States black carbon emission inventory with explicit representation of activity and technology between 1960 and 2000. We compare measured coefficient of haze data in California and New Jersey between 1965 and 2000 with predicted concentration trends and attribute discrepancies between observations and predicted concentrations among several sources based on seasonal and weekly patterns in observations. Emission factors for sources with distinct fuel trends are then estimated by comparing fuel and concentration trends and further substantiated by in‐depth examination of emission measurements. We recommend (1) increasing emission factors for preregulation vehicles by 80–250%; (2) increasing emission factors for residential heating stoves and boilers by 70% to 200% for 1980s and before; (3) explicitly representing naturally aspired off‐road engines for 1980s and before; and (4) explicitly representing certified wood stoves after 1985. We also evaluate other possible sources for discrepancy between model and measurement, including bias in modeled meteorology, subgrid spatial heterogeneity of concentrations, and inconsistencies in reported fuel consumption. The updated U.S. emissions are higher than thea prioriestimate by 80% between 1960 and 1980, totaling 690 Gg/year in 1960 and 620 Gg/year in 1970 (excluding open burning). The revised inventory shows a strongly decreasing trend that was present in the observations but missing in thea prioriinventory.
Warmer Winter Ground Temperatures Trigger Rapid Growth of Dahurian Larch in the Permafrost Forests of Northeast China
Authors: Zhang Xianliang , Bai Xueping , Hou Meiting , Chen Zhenju , Manzanedo Rubén D. 
Published: March 2019

AbstractPermafrost degradation due to rapid increase in ground surface temperature (GST) in recent years may strongly affect boreal forest ecosystems. However, comparatively few studies have explored how changes in permafrost affect tree growth dynamics in boreal forest. Here, we used a tree ring network of 12 Dahurian larch (Larix gmelinii) sites across permafrost regions in northeast China. We observed an increase in L. gmelinii growth over the past decade, seemingly linked to a shift in their climatic limitations, where winter GST has become the most strongly limiting factor for L. gmelinii growth. The recent increase in growth was particularly strong in older trees (>300 years), which could be related to older trees having a more developed root system. GST was the main limiting factor for tree growth. While summer GST had a somewhat consistently positive correlation with tree growth, winter GST has shifted from a negative to a strongly positive correlation with growth in the last decade, coincidental with a sharp increase in winter GST since 2004. Winter GST is also strongly correlated with the rapidly thawing permafrost dynamics. Overall, our results suggest a link between recent changes in the permafrost and shifts in climate‐growth correlations for one of the main boreal tree species. As a result, L. gmelinii has experienced an important increase in radial growth that may indicate that, unlike what has been reported for other boreal species, it may temporally benefit from warming climate in the continuous permafrost region of the Asian boreal forests.
Cenozoic Stages of Forearc Evolution Following the Accretion of a Sliver From the Late Cretaceous‐Caribbean Large Igneous Province: SW Ecuador‐NW Peru
Authors: Aizprua Carlos , Witt Cesar , Johansen Ståle E. , Barba Diego 
Published: March 2019

AbstractThe SW Ecuador‐NW Peru forearc region is the southernmost location, where the Caribbean large igneous province (CLIP) interacted with the South American margin since the Late Cretaceous. The accretion of the CLIP to the margin led to the entrapment of the North Andean crustal Sliver, conforming the underlying basement of the forearc region in Ecuador, whereas in NW Peru, forearc depocenters involve rocks of continental affinity. Many existing tectonic reconstructions have treated these two areas independently, largely based on their crustal affinities. In contrast, this study integrates previous studies into an analysis of unpublished seismic profiles, potential field data, outcrop stratigraphy, and recent studies dealing with the dynamics of allochthonous terrane accretion along continental margins. Our integrated approach shows that SW Ecuador was dominated by a Late Cretaceous deforming outer wedge, which may have constituted a remnant of a northeast or northwest dipping obliquely obducted oceanic block at the edge of the CLIP. This tectonic phase was governed by plate instability, affecting NW Peru and SW Ecuador, followed by reestablishment of the margin by early Eocene. The resulting margin configuration and the spatial distribution of the different tectonic elements seem to have played a key role into the further Cenozoic development of the forearc region. The model presented in this study proposes that the accretion of buoyant oceanic terranes may have had a profound impact on the early margin configuration of SW Ecuador and NW Peru and led to the development of localized but genetically related forearc depocenters.
Simulation of Counterstreaming H+ Outflows During Plasmasphere Refilling
Authors: Krall J. , Huba J. D. 
Published: March 2019

AbstractPlasmasphere refilling is modeled using an upgraded version of the Naval Research Laboratory SAMI2 (Sami2 is Another Model of the Ionosphere) ionosphere/plasmasphere code. In this implementation of SAMI2, two fluid species are used for H+, each having a source in only one magnetic hemisphere. This is the first comprehensive plasmasphere model with two‐stream H+. With two counterstreaming H+ fluids, artificial shocks or compressions at high altitude are avoided during storms and early‐stage refilling. For late‐stage refilling, runs with two‐stream SAMI2 validate previous SAMI2 (one H+ fluid) refilling rates. At ionospheric altitudes (
2,000 km), where the single‐fluid approximation is valid for each ion, two‐stream SAMI2 results agree closely with SAMI2 results.
Direct Evidence for the Dissipation of Small‐Scale Ionospheric Plasma Structures by a Conductive E Region
Authors: Ivarsen Magnus F , Jin Yaqi , Spicher Andres , Clausen Lasse B N 
Published: March 2019

AbstractThe conductivity of the ionospheric E region is known to cause effective dissipation of plasma structures in the F region. We use 3.5 years of 16‐Hz sampling rate electron density measurements from the Swarm advanced data set to investigate seasonal dependencies of plasma structure dissipation. Using a novel algorithm to infer plasma structure dissipation through detection of spectral breaks in density fluctuation power spectra, we analyze 100,000 spectra based on data from Swarm A in both the northern and southern polar caps. For the first time, we can present long‐term development of small‐scale (∼1‐10 km) plasma structure diffusion in the high‐latitude ionospheric F region. We discuss possible reasons for these variations. This study presents evidence for the E region as an important factor in the seasonal variation of F region plasma irregularity amplitudes.
Thank You to Our 2018 Peer Reviewers
Authors: Florindo Fabio , Halekas Jasper S. , Okin Gregory , Robock Alan , Rohling Eelco J. 
Published: March 2019

AbstractOn behalf of the authors and readers of Reviews of Geophysics, the American Geophysical Union (AGU), and the broader scientific community, the Editors wish to wholeheartedly thank those who reviewed the manuscripts for Reviews of Geophysics in 2018. Reviews of Geophysics is the top rated journal in Geophysics and Geochemistry and it could not exist without your investment of time and effort, lending your expertise to ensure that the papers published in this journal meet the standards that the research community expects for it. We sincerely appreciate the time spent reading and commenting on manuscripts, and we are very grateful for your willingness and readiness to serve in this role. Reviews of Geophysics published 20 review papers and an editorial in 2018, covering most of the AGU Section topics, and for this we were able to rely on the efforts of 85 dedicated reviewers from 20 countries. Many reviewers answered the call multiple times. Thank you again. We look forward to a 2019 of exciting advances in the field and communicating those advances to our community and to the broader public.
Thank You to Our 2018 Peer Reviewers
Authors: Salous Sana , Wilkinson Phil 
Published: March 2019

AbstractScience operates best by sharing accurate new knowledge in clear ways. In order to check our assumptions, our methods, and our interpretations of the observations, experiments, analyses, and calculations that we do, we ask experts who were not involved in the study to critically evaluate our work. We call this peer review. They look for completeness, accuracy, whether work is new, and how clearly we have written the descriptions. We continue to be humbled by the time, effort, and careful insights that our colleagues share with each other through the process of peer review. In 2018, Radio Science benefited from 720 reviews provided by 420 of our peers for papers submitted to the journal. Thank you all for your efforts toward advancing radio science now and for the future.
Tissue resident and follicular Treg cell differentiation is regulated by CRAC channels
Authors: Vaeth Martin , Wang Yin-Hu , Eckstein Miriam , Yang Jun , Silverman Gregg J. , Lacruz Rodrigo S. , Kannan Kasthuri , Feske Stefan 
Published: March 2019

AbstractT regulatory (Treg) cells maintain immunological tolerance and organ homeostasis. Activated Treg cells differentiate into effector Treg subsets that acquire tissue-specific functions. Ca2+ influx via Ca2+ release-activated Ca2+ (CRAC) channels formed by STIM and ORAI proteins is required for the thymic development of Treg cells, but its function in mature Treg cells remains unclear. Here we show that deletion of Stim1 and Stim2 genes in mature Treg cells abolishes Ca2+ signaling and prevents their differentiation into follicular Treg and tissue-resident Treg cells. Transcriptional profiling of STIM1/STIM2-deficient Treg cells reveals that Ca2+ signaling regulates transcription factors and signaling pathways that control the identity and effector differentiation of Treg cells. In the absence of STIM1/STIM2 in Treg cells, mice develop a broad spectrum of autoantibodies and fatal multiorgan inflammation. Our findings establish a critical role of CRAC channels in controlling lineage identity and effector functions of Treg cells.
Live imaging of alveologenesis in precision-cut lung slices reveals dynamic epithelial cell behaviour
Authors: Akram Khondoker M. , Yates Laura L. , Mongey Róisín , Rothery Stephen , Gaboriau David C. A. , Sanderson Jeremy , Hind Matthew , Griffiths Mark , Dean Charlotte H. 
Published: March 2019

AbstractDamage to alveoli, the gas-exchanging region of the lungs, is a component of many chronic and acute lung diseases. In addition, insufficient generation of alveoli results in bronchopulmonary dysplasia, a disease of prematurity. Therefore visualising the process of alveolar development (alveologenesis) is critical for our understanding of lung homeostasis and for the development of treatments to repair and regenerate lung tissue. Here we show live alveologenesis, using long-term, time-lapse imaging of precision-cut lung slices. We reveal that during this process, epithelial cells are highly mobile and we identify specific cell behaviours that contribute to alveologenesis: cell clustering, hollowing and cell extension. Using the cytoskeleton inhibitors blebbistatin and cytochalasin D, we show that cell migration is a key driver of alveologenesis. This study reveals important novel information about lung biology and provides a new system in which to manipulate alveologenesis genetically and pharmacologically.