bluuebunny/crossref_metadata_2025_split huggingface dataset:
Decomposition of Deglacial Pacific Radiocarbon Age Controls Using an Isotope‐Enabled Ocean Model
Authors: Zanowski Hannah , Jahn Alexandra , Gu Sifan , Liu Zhengyu , Marchitto Thomas M. 
Published: July 2022

AbstractDuring the last deglaciation Earth’s climate experienced strong and abrupt variations, resulting in major changes in global temperature, sea level, and ocean circulation. Although proxy records have significantly improved our understanding of climate during this period, questions remain regarding the connection between ocean circulation evolution and resulting geotracer distributions, including those of deep waters in the Pacific. Here we use the C‐iTRACE simulation, a transient ocean‐only, isotope‐enabled version of the Community Earth System Model, to better understand deglacial deep Pacific radiocarbon evolution in the context of circulation and reservoir age changes. Throughout the deglaciation, the Pacific Ocean circulation in C‐iTRACE responds strongly to glacial meltwater forcing, leading to large changes in deep Pacific Δ14C age. A multi‐millennial weakening of the overturning circulation from 20 to 15 ka BP leads to increases in deep Pacific Δ14C ages, but from 20 to 18 ka BP, nearly half (40%–60%) of this aging is controlled by changing surface reservoir age, corroborating previous studies showing that Δ14C is not solely a circulation age tracer. As the deglaciation proceeds, circulation change controls progressively more of the Δ14C age, accounting for more than 75% of it across the deep Pacific from 15 to 8 ka BP.
Late‐Syn‐ to Post‐Rift Salt Tectonics on Wide Rifted Margins—Insights From Geodynamic Modeling
Authors: Pichel Leonardo M. , Huismans Ritske S. , Gawthorpe Robert , Faleide Jan Inge , Theunissen Thomas 
Published: July 2022

AbstractRifted margins are often associated with widespread and thick evaporite (salt) deposits and pronounced salt tectonics. The largest salt basins formed during the latest stages of rifting, immediately prior to continental breakup. Salt tectonics along these rifted margins commonly exhibit structural domains characterized by gravity‐driven updip extension, translation, downdip shortening, and salt nappe advance. The precise spatial and temporal links between these structural processes, their relative contributions and dynamics are still a topic of debate on many margins. We use 2D thermo‐mechanically coupled finite‐element modeling of lithospheric extension to investigate the evolution of salt tectonics along wide rifted margins and the interplay between rifting and post‐rift deformation. The models integrate lithospheric extension with post‐rift salt tectonics using a geodynamically self‐consistent approach where the geometries of the lithosphere and salt basins are not prescribed. They confirm that wide salt‐bearing rifted margins are characterized by gravity‐driven updip extension and downdip shortening, but also that syn‐depositional salt flow and salt stretching occurs in their distal portions prior to and during continental breakup. This produces widening of the basin and emplacement of a salt nappe over newly formed oceanic crust. Post‐rift updip extension is mostly balanced by downdip diapir shortening, all related to Couette flow. The salt nappe initiated by late syn‐rift stretching advances further by post‐rift pressure‐driven Poiseuille salt flow so that its final width is a product of both processes. The results can be directly compared to examples from various salt‐bearing rifted margins and improve our understanding of their enigmatic genesis and evolution.
The Mass Change Designated Observable Study: Overview and Results
Authors: Wiese D. N. , Bienstock B. , Blackwood C. , Chrone J. , Loomis B. D. , Sauber J. , Rodell M. , Baize R. , Bearden D. , Case K. , Horner S. , Luthcke S. , Reager J. T. , Srinivasan M. , Tsaoussi L. , Webb F. , Whitehurst A. , Zlotnicki V. 
Published: July 2022

AbstractThe 2017–2027 United States National Academy of Sciences Decadal Survey (DS) for Earth Science and Applications from Space identified Mass Change (MC) as one of five Designated Observables (DOs) having the highest priority in terms of Earth observations required to advance Earth system science over the next decade. In response to this designation, NASA initiated several multi‐center studies, with the goal of recommending observing system architectures for each DO for implementation within this decade. This paper provides an overview of the Mass Change Designated Observable (MCDO) Study along with key findings. The study process included: (a) generation of a Science and Applications Traceability Matrix (SATM) that maps required measurement parameters to the DS Science and Applications Objectives; (b) identification of three architecture classes relevant for measuring mass change: Precise Orbit Determination (POD), Satellite‐Satellite‐Tracking (SST) and Gravity Gradiometry (GG), along with variants within each architecture class; and (c) creation of a Value Framework process that considers science value, cost, risk, schedule, and partnership opportunities, to identify and recommend high value observing systems for further in‐depth study. The study team recommended the implementation of an SST architecture, and identified variants that simultaneously (a) satisfy the baseline measurement parameters of the SATM; (b) maximize the probability of providing overlap with the Gravity Recovery and Climate Experiment Follow‐On (GRACE‐FO) mission currently in operation, accelerating science return from both missions; and (c) provide a pathway towards substantial improvements in resolution and accuracy of mass change data products relative to the program of record.
Detection of Magma Beneath the Northern and Southern Rift Zones of Axial Seamount at the Juan de Fuca Ridge
Authors: Lee Michelle K. , Carbotte Suzanne M. , Arnulf Adrien F. 
Published: July 2022

AbstractAxial Seamount is an active hotspot‐related volcanic system located along the Juan de Fuca Ridge (JdFR) that includes a central volcano and bounding northern and southern rift zones (NRZ and SRZ). Three documented volcanic eruptions in 1998, 2011, and 2015 included dike propagation into and eruptions within the rift zones that are believed to have been sourced from the well‐imaged large magma reservoir found beneath the central volcano. However, areas beyond the central volcano have not been explored for potential magma sources that could have contributed to these events, and geochemical studies of older rift zone lavas indicate differences in compositions suggestive of magma reservoirs fed by more mid‐ocean ridge‐dominated mantle sources. In this study, we analyze multichannel seismic data acquired in 2002 to characterize the internal crustal structure of the rift zones. The new reflectivity images reveal small (<5 km wide) and discontinuous crustal magma bodies at depths of ∼1.5 to 4 km beneath and in the vicinity of the rift zone lava flows from the three eruptions. We also image wide magma bodies within the overlap regions between the rift zones and neighboring segments of JdFR including a 6.4 km wide body under the east flank of NRZ and a 1‐km wide, ∼400 to 500 m, thick body near the base of the crust under the SRZ‐Vance overlap basin. Collectively the new observations indicate that multiple small crustal magma bodies underlie Axial segment, in addition to the main reservoir, and likely contribute to rift zone magmatism with implications for interpretations of seismicity patterns and lava flow compositions.
Increasing Health Risks During Outdoor Sports Due To Climate Change in Texas: Projections Versus Attitudes
Authors: Dee Sylvia G. , Nabizadeh Ebrahim , Nittrouer Christine L. , Baldwin Jane W. , Li Chelsea , Gaviria Lizzy , Guo Selena , Lu Karen , Saunders‐Shultz Beck Miguel , Gurwitz Emily , Samarth Gargi , Weinberger Kate R. 
Published: July 2022

AbstractExtreme heat is a recognized threat to human health. This study examines projected future trends of multiple measures of extreme heat across Texas throughout the next century, and evaluates the expected climate changes alongside Texas athletic staff (coach and athletic trainer) attitudes toward heat and climate change. Numerical climate simulations from the recently published Community Earth System Model version 2 and the Climate Model Intercomparison Project were used to predict changes in summer temperatures, heat indices, and wet bulb temperatures across Texas and also within specific metropolitan areas. A survey examining attitudes toward the effects of climate change on athletic programs and student athlete health was also distributed to high‐school and university athletic staff. Heat indices are projected to increase beyond what is considered healthy/safe limits for outdoor sports activity by the mid‐to‐late 21st century. Survey results reveal a general understanding and acceptance of climate change and a need for adjustments in accordance with more dangerous heat‐related events. However, a portion of athletic staff still do not acknowledge the changing climate and its implications for student athlete health and their athletic programs. Enhancing climate change and health communication across the state may initiate important changes to athletic programs (e.g., timing, duration, intensity, and location of practices), which should be made in accordance with increasingly dangerous temperatures and weather conditions. This work employs a novel interdisciplinary approach to evaluate future heat projections alongside attitudes from athletic communities toward climate change.
Width‐Based Discharge Partitioning in Distributary Networks: How Right We Are
Authors: Hariharan Jayaram , Piliouras Anastasia , Schwenk Jon , Passalacqua Paola 
Published: July 2022

AbstractRiver deltas are home to large populations and can be composed of complex channel networks which convey flows of matter to the shoreline. Knowledge of flow within individual channels is needed to quantify the distribution of discharge across the delta, and thus its sustainability over time. Due to a lack of field measurements at the local channel scale, researchers leverage remote sensing data to estimate the partitioning of flow. We compare data from 15 river deltas to discharge partitioning estimates based on channel network graphs derived from remote sensing imagery. We quantify errors in the common width‐based method and test alternative partitioning techniques to find that width‐based discharge partitioning is universally applicable, suggesting that absent any site‐specific information, discharge partitioning by average channel width is an appropriate approach. We also provide networks, streamflow measurements, and flux partitioning estimates for 28 delta networks as the Discharge In Distributary NeTworks (DIDNT) dataset.
Observational Evidence of Generation and Propagation of Barotropic Rossby Waves Induced by Tropical Instability Waves in the Northeastern Pacific
Authors: Lee Kang‐Nyeong , Jeon Chanhyung , Seung YoungHo , Shin Hong‐Ryeol , Son Seung‐Kyu , Park Jae‐Hun 
Published: July 2022

AbstractTropical instability waves (TIWs) in the equatorial eastern Pacific exhibit 25–40‐day westward‐propagating fluctuations with seasonal and interannual variations, which are stronger during July–December and La Niña periods. There is evidence that the instability of the equatorial currents that generates TIWs also induce radiation of barotropic Rossby waves (BTRWTIW). Long‐term near‐bottom current measurements at 10.5°N and 131.3°W during 2004–2013 revealed a spectral peak at 25–40 days, where significant coherences were found with satellite‐measured sea surface height with maxima approximately 5°N. Simulated deep currents from a data‐assimilated ocean model concur with the observed near‐bottom currents, and both currents vary seasonally and interannually, consistent with the typical characteristics of TIW. Further analyses using 25–40‐day bandpass‐filtered barotropic velocity data from the model revealed that they reasonably satisfied the theoretical dispersion relation of BTRWTIW. The in situ and model analysis support the conclusion that BTRWTIW propagate north of 10°N in the northeastern Pacific.
Core Surface Flow Changes Associated With the 2017 Pacific Geomagnetic Jerk
Authors: Whaler K. A. , Hammer M. D. , Finlay C. C. , Olsen N. 
Published: July 2022

AbstractA geomagnetic jerk was seen in Swarm satellite data in 2017 over the Pacific region. We invert time series of spatial gradient secular variation data between 2014 and 2020, reduced to a grid of points at satellite altitude, for spatially‐ and temporally‐regularized core surface flow. Pacific region flow acceleration was almost constant before and after the jerk, with a sharp change, especially in the azimuthal component, at the jerk epoch, despite the temporal regularization. Azimuthal acceleration is oppositely signed either side of 160°W, where it effectively vanishes, and also reverses sign at the jerk epoch. Acceleration features drift westward at about 900 km year−1. Unlike previous studies, the evidence presented here for low latitude waves does not depend on imposing flow equatorial symmetry, quasi‐ or tangential geostrophy, or band‐pass filtering, and has no reliance on stochastic models or numerical simulations.
Fugitive Gas Migration in the Vadose Zone at an Experimental Field Site in the Montney Shale Gas Region
Authors: Forde Olenka N. , Cahill Aaron G. , Mayer Bernhard , Beckie Roger D. , Mayer K. Ulrich 
Published: July 2022

AbstractFugitive gas migration (GM) from compromised oil and gas wells remains a global concern. To understand environmental impacts from GM there is a need to characterize the transport and fate of fugitive gas in the vadose zone. We simulated subsurface wellbore leakage by injecting natural gas into thick unsaturated glacio‐lacustrine deposits in a region of petroleum development in Western Canada. Methane and carbon dioxide effluxes were monitored and soil‐gas samples were collected for molecular and stable carbon isotope analyses. A conceptual model was developed to demonstrate the physical and biogeochemical processes that control the spatial‐temporal variability of GM. Methane oxidation partially attenuated natural gas; however, gas transport and fate were strongly influenced by variations in grain‐size distribution and barometric pressure, resulting in episodic effluxes and lateral gas transport. To accurately detect, quantify and assess GM at oil and gas sites, adequate site characterization and continuous, spatially dense monitoring are necessary.
Electron Energization Signatures in Traveling Kinetic Alfvén Waves at Storm Time Injection Fronts
Authors: Hull A. J. , Damiano P. A. , Chaston C. C. , Johnson J. R. , Reeves G. D. 
Published: July 2022

AbstractThe properties of traveling kinetic Alfvén waves (KAWs) and their role in energizing electrons in the inner magnetosphere during a geomagnetic storm are examined using measurements from the Van Allen Probes and Gyrofluid‐Kinetic Electron (GKE) model simulations. Traveling KAWs occur in the vicinity of energetic plasma injection fronts in association with magnetic field dipolarizations. The KAWs coincide with energized field‐aligned electrons at energies ≲1 keV. By using observational constraints and incorporating hot and cold electron populations, the GKE simulations are able to reproduce the observed energized electron distribution signatures. The modeling results demonstrate the crucial importance of cold electrons for best observational agreement. The results show that the electron response to KAWs can be substantially different for opposing current regions and are a sensitive function of the cold electron relative density.
Active Silica Diagenesis in the Deepest Hadal Trench Sediments
Authors: Luo Min , Li Weiding , Geilert Sonja , Dale Andrew W. , Song Zijun , Chen Duofu 
Published: July 2022

AbstractPorewater dissolved silicic acid (DSi) concentrations and stable Si isotope compositions (δ30Si) together with biogenic silica (bSiO2) contents of sediments in five sediment cores collected from the southern Mariana Trench are presented. These data suggest the occurrence of bSiO2 dissolution and concomitant authigenic clay formation in three bSiO2‐bearing cores. A reaction‐transport model constrained by the measured geochemical data was applied to quantify the rates of Si turnover. Model results predicted the greatest rates of both bSiO2 dissolution and authigenic clay formation at the trench axis core that displayed low bSiO2 contents and abundant detrital materials, suggesting that detrital materials may be a limiting factor for bSiO2 diagenesis. Model results further predicted that ∼40%–70% of DSi generated by bSiO2 dissolution is consumed by authigenic clay formation. This is the first study that demonstrates active silica diagenesis in the hadal realm and has implications for understanding benthic Si cycling in deep‐sea settings.
Spectral Analysis of the Martian Atmospheric Turbulence: InSight Observations
Authors: Temel Orkun , Senel Cem Berk , Spiga Aymeric , Murdoch Naomi , Banfield Don , Karatekin Ozgur 
Published: July 2022

AbstractIn this study, we perform spectral analysis of Martian near‐surface turbulence using the in‐situ observations by NASA's InSight lander on Mars. A recent study on the daytime Martian boundary layer using the InSight observations showed that the conventional Kolmogorov energy cascade of inertial subrange fails to predict the spectral density of pressure (Banfield et al., 2020, https://doi.org/10.1038/s41561-020-0544-y). Here we extend this by investigating diurnal and seasonal variations in the spectral density of pressure, as the indicator of the Martian atmospheric turbulence. We show distinct spectral behaviors for the daytime and nighttime conditions. Moreover, we report the important effects of regional dust storms, gravity waves (GWs), bore, and solitary waves on the turbulent energy cascade. Our results show that the presence of a dust storm and GW activity can enhance the turbulence of the nighttime boundary layer of Mars despite the extreme stably stratified conditions compared to the terrestrial case.
Ongoing Lithospheric Alteration of the North China Craton Revealed by Surface‐Wave Tomography and Geodetic Observations
Authors: Feng J. K. , Yao H. J. , Chen L. , Li C. L. 
Published: July 2022

AbstractThe North China Craton (NCC) is renowned for cratonic reactivation and dramatic destruction. Detailed lithospheric structure is crucial for understanding the geological evolution and seismogenesis of the NCC. We imaged the lithospheric structure of the central and eastern NCC with ambient noise and teleseismic surface wave tomography. Our new model unveils remarkable N‐S variation in the lithospheric structure. An E‐W elongated lithospheric weak zone, coinciding with contemporary left‐lateral shearing revealed by geodetic observation, occupies the northern central and eastern NCC. Our model suggests that radical destruction of the eastern NCC in the late Mesozoic facilitated the late‐Cenozoic shearing induced by the continuous India‐Eurasia convergence. The late‐Cenozoic shearing progressively altered the pre‐thinned lithosphere accompanied by asthenospheric upwelling and strong seismic activity. Our results suggest a transition from the Pacific subduction dominating tectonic regime to the India‐Asia collision dominating lithospheric deformation framework in the Cenozoic and ongoing lithospheric alteration of the NCC.
On the Relation Between Active Network Length and Catchment Discharge
Authors: Durighetto Nicola , Botter Gianluca 
Published: July 2022

AbstractThe ever‐changing hydroclimatic conditions of the landscape induce ceaseless variations in the wet channel length (L) and the streamflow (Q) of a catchment. Here we use a perceptual model to analyze the links among (and the drivers of) four descriptors commonly used to characterize discharge and active length dynamics in streams, namely the L(Q) relationship and the cumulative distributions of local persistency, flowrate and active length. The model demonstrates that the shape of the L(Q) law is defined by the cumulative distribution of the specific subsurface discharge capacity along the network, a finding which provides a clue for the parametrization of L(Q) relations in dynamic streams. Furthermore, we show that L(Q) laws can be constructed combining the streamflow distribution with disjoint active length data. Our framework links previously unconnected formulations for characterizing stream network dynamics, and offers a novel perspective to describe the scaling between wet length and discharge in rivers.
Earthquake Fingerprint of an Incipient Subduction of a Bathymetric High
Authors: Passarelli Luigi , Cesca Simone , Nooshiri Nima , Jónsson Sigurjón 
Published: July 2022

AbstractThe resistance of bathymetric highs to subduction results in large‐scale morphological distortions of the outer‐rise, trench, and fore‐arc regions. Once subducted, bathymetric highs induce frictional segmentation along the plate interface that may result in increase or decrease of the plate coupling. However, the mechanics of the collision is inferred mostly from geophysical and geological surveys since earthquakes rarely illuminate finer details of the subduction of seafloor relief. A year‐long and energetic seismic sequence at the Loyalty Ridge (LR)‐Vanuatu Trench allowed us to characterize how strain is released along the collision zone. Earthquakes revealed complex fracturing in the outer‐rise and fore‐arc regions and segmentation of the interface with both limited magnitude events and aftershock productivity. The complex earthquake activity associated to the collision and subduction of the LR appears to support a frictionally segmented interface where Mw ≥ 8 megathrust earthquakes are unlikely to nucleate.
QBO and ENSO Effects on the Mean Meridional Circulation, Polar Vortex, Subtropical Westerly Jets, and Wave Patterns During Boreal Winter
Authors: Kumar Vinay , Yoden Shigeo , Hitchman Matthew H. 
Published: July 2022

AbstractThe joint influence of the stratospheric quasi‐biennial oscillation (QBO) and the El Niño Southern Oscillation (ENSO) on the polar vortex, subtropical westerly jets (STJs), and wave patterns during boreal winter is investigated in 40 years (1979–2018) of monthly mean ERA‐Interim reanalyses. The method of Wallace et al. (1993), https://doi.org/10.1175/15200469(1993)050<1751:ROTESQ>2.0.CO;2 is used to conduct a QBO phase angle sweep. QBO westerly (W) and easterly (E) composites are then segregated by the phase of ENSO. Two pathways are described by which the QBO mean meridional circulation (MMC) influences the northern winter hemisphere. The “stratospheric pathway” modulates stratospheric planetary wave absorption via the Holton‐Tan mechanism. The “tropospheric pathway” modulates the tropical and subtropical upper troposphere and lower stratosphere. QBO MMC anomalies exhibit a checkerboard pattern in temperature and arched structures in zonal wind which extend into midlatitudes, and are stronger on the winter side. During QBO W, the polar vortex and STJs are enhanced. QBO signals in the polar vortex are amplified during La Niña. During El Niño and QBO W, the strongest STJs occur, and a warm pole/wave two pattern is found. During El Niño and QBO E, a trough is found over Eurasia and a ridge over the North Atlantic, in a wave one pattern. El Niño diminishes QBO anomalies in the tropical stratosphere and reduces the poleward extent and amplitude of the QBO MMC, thereby influencing the stratospheric pathway. Effects on the boreal winter hemisphere are attributed to the combined influence of the QBO and ENSO via both pathways.