bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Paleomagnetic Bias in Ediacaran Global Paleogeographic Reconstructions
Authors: Wu Lei , Murphy J. Brendan , Nance R. Damian 
Published: December 2022

AbstractPaleogeographic models provide first‐order insights into Earth's tectonic evolution in deep geologic time. However, there is a lack of objective metrics to distinguish between rival models. Using a recent compilation of reliable Precambrian paleomagnetic data, we quantify the extent of paleomagnetic compliance of existing Ediacaran global reconstruction models. We determine spherical arc distances between modeled paleopositions of the geographic South Pole and reconstructed coordinates of all paleopoles from a continent acquired at various times. We identify significant paleomagnetic bias for a reconstructed location of a continent if arc distances of the majority of high‐quality paleopoles with reliable age constraints are greater than their standard errors at the 95% confidence interval. Our study provides quantifiable measures of paleogeographic bias that allows researchers to make informed decisions when selecting among existing global models as a foundation for interpreting their geologic data.
Diverse Interannual Variability of Asian Summer Monsoon Onset Process
Authors: Liu Boqi , Duan Yanan 
Published: December 2022

AbstractThe onset of the Asian summer monsoon (ASM) starts the rainy season in one of the most world populous regions. The present study found that the stepwise ASM onset process (ASMOP) in the Bay of Bengal, South China Sea (SCS), and India exhibits three distinct interannual modes induced by different sea surface temperature anomalies (SSTAs). The first mode features are in‐phase variation of ASMOP in southern Asia, which originates from the ENSO‐related SSTAs and anomalous circulations in the tropical Indo‐Pacific Ocean. The second mode indicates the anomalous ASMOP in India and depends on the southwestern Indian SSTAs that alter the low‐level cross‐equatorial flow over the Arabian Sea. In the third mode, the western North Pacific SSTAs and their resultant circulation anomalies regulate ASMOP in the northern SCS. These extra‐equatorial SSTAs and their associated air‐sea interaction serve as an additional source of seasonal predictability for ASMOP besides El Niño–Southern Oscillation events.
Seasonal Predictability of the East Atlantic Pattern in Late Autumn and Early Winter
Authors: Thornton H. E. , Smith D. M. , Scaife A. A. , Dunstone N. J. 
Published: December 2022

AbstractThe North Atlantic Oscillation (“NAO”) and the East Atlantic Pattern (“EAP”) dominate winter atmospheric variability over the North Atlantic. Unlike the NAO, seasonal predictability of the EAP has remained elusive. A multi‐model ensemble of seasonal predictions yields skillful forecasts of the EAP in late autumn and early winter, complementing NAO prediction skill in winter. The shift in prediction skill from EAP to NAO reflects the ability of the ensemble to forecast the evolving influence of the El Niño South Oscillation on the North Atlantic region. In early winter, the ensemble correctly forecasts the key tropical–extratropical teleconnections, resulting in skillful predictions of the EAP and western European temperatures and rainfall. However, the modeled tropical–extratropical teleconnections are weak compared to observations, contributing to a signal to noise error in predictions of the EAP. Improving the strength of such teleconnections would improve predictions of the EAP and associated surface climate.
Characterization of Aquifer Poroelastic Response to Impulse and Oscillatory Well Pressure Using Distributed Acoustic Sensing
Authors: Becker Matthew W. , Harris Brett , Pevzner Roman 
Published: December 2022

AbstractThe storage of fluids in the subsurface is critical for a broad spectrum of applications including managed aquifer recharge, storage of liquefied carbon dioxide and hydrogen, geothermal heat extraction and exploitation of hydrocarbon. It is surprising then, that there has been relatively little measurement of the vertical distribution of poroelastic storage in geologic formations as compared with permeability. We present experiments in which fluid was injected into an important regional aquifer and the depth‐dependent strain response measured using fiber optic distributed acoustic sensing. The formation expansion and contraction in response to fluid injection were several 100 nanostrain. Strain, and the implied storage distribution, was highly localized in specific strata and demonstrated complex, hydromechanical behavior. This new window into fluid‐geomechanical coupling undermines some typically use models and observations currently in practice, but provides potential for complete representation and prediction of fluid storage in the subsurface.
Flow‐To‐Fracture Transition of Linear Maxwell‐Type Versus Yield Strength Fluids by Air Injection—Implications for Magma Fracturing
Authors: Sánchez Claudia , Ichihara Mie , Kuwano Osamu 
Published: December 2022

AbstractTo illuminate brittle and ductile fracturing of magma, we investigated bubble expansion and fracturing in two contrasting fluids: a Maxwell‐type viscoelastic fluid and a Bingham‐type yield‐strength fluid. Measurements of the complex shear modulus, G′ + iG″ (i is the imaginary unit), under small‐strain oscillation showed that both fluids are elastic (G′ > G″) with similar rigidity. Viscous behavior (G′ < G″) appeared at lower frequency in the Maxwell fluid but at larger strain in the Bingham fluid. When we injected air into the Maxwell fluid, bubbles expanded viscously at low flux, fractured in a brittle manner at high flux, and behaved transitionally at intermediate flux. In contrast, we observed no fracturing in the Bingham fluid. This demonstrates that the G′ > G″ condition is insufficient to infer that brittle fracturing can occur. Brittle fracturing of the Maxwell fluid occurred not at a critical strain rate but under decreasing strain rate and increasing stress.
A “Floatilla” of Airborne Seismometers for Venus
Authors: Krishnamoorthy Siddharth , Bowman Daniel C. 
Published: December 2022

AbstractBarometers floating on high‐altitude balloons in the relatively clement cloud layer on Venus could detect and characterize acoustic waves generated by seismic activity, avoiding the need for high‐temperature electronics required for surface seismology. Garcia et al. (2022, https://doi.org/10.1029/2022GL098844) recently demonstrated the detection of low‐frequency sound (infrasound) caused by earthquakes of magnitudes 7.3 and 7.5 from stratospheric balloons nearly 3,000 km away from the epicenter. They provided a preliminary demonstration of earthquake magnitude and location inversion, and the determination of S‐ and Rayleigh wave velocities using only their acoustic signature. Large earthquakes produce low‐frequency seismic waves that penetrate the interiors of planets; their detection at continental‐scale distances from a high‐vantage point demonstrates the feasibility of balloon‐based investigations of Venus' interior. We contextualize these results within the effort to perform seismology on Venus from balloons, discuss its limitations, and share perspectives on open research questions in this area.
Sensitivity of the Tropical Dust Cycle to Glacial Abrupt Climate Changes
Authors: Hopcroft Peter O. , Pichat Sylvain , Valdes Paul J. , Kienast Stephanie S. 
Published: December 2022

AbstractDuring abrupt climate changes of the last glacial period paleorecords show large amplitude changes in the dust cycle. We use Earth System model simulations to evaluate processes operating across these events. Idealized Heinrich stadial‐like simulations show a southwards migration of tropical rainfall that dries the Sahel and reduces wet deposition causing a widespread enhancement of tropical dust loading. However, several discrepancies with marine core dust deposition reconstructions are evident. Simulations with a more limited freshwater forcing (0.4 Sv instead of 1.0 Sv) and weaker cooling over the North Atlantic (less than 3°C) show a switch in sign of the stadial dust deposition anomaly in several regions, improving agreement with paleorecords. The simulated dust cycle therefore displays in places a non‐linear response to abrupt change. The global‐mean stadial dust radiative forcing in the more realistic simulations is around −0.2 to −0.6 W m−2 and so could represent an amplifying feedback during these events.
Fracture‐Mesh Faulting in the Swarm‐Like 2020 Maacama Sequence Revealed by High‐Precision Earthquake Detection, Location, and Focal Mechanisms
Authors: Shelly David R. , Skoumal Robert J. , Hardebeck Jeanne L. 
Published: December 2022

AbstractIn August of 2020, an earthquake sequence initiated within the Maacama fault zone in northern California, raising questions about its relationship with the larger‐scale fault. To investigate the faulting geometry and its implications for physical processes driving seismicity, we applied an integrated, multi‐faceted seismic analysis including waveform‐correlation‐based event detection, relative relocation, and high‐precision focal mechanisms. To determine mechanisms for a large population of very small earthquakes (predominantly M < 1), we combined correlation‐derived polarity analysis with a recently developed technique to determine S/P amplitude ratios from single seismic components. Finally, we applied an iterative stress inversion to distinguish between the likely fault and auxiliary planes. This analysis reveals that although the sequence initiated on a right‐lateral fault, plausibly a strand of the Maacama Fault, it also activated numerous en echelon left‐lateral conjugate faults. Together, these interlocking faults form a fracture mesh, consistent with structures associated elsewhere with fluid‐induced faulting and earthquake swarms.
Soil Stratum Tides
Authors: Shi Bin , Zhang Cheng‐Cheng , Fang Ke , Shi Songge , Wei Guangqing , Hoitink A. J. F. 
Published: December 2022

AbstractRiver deltas, where ocean tides can often freely propagate into the river, are focal points of human settlement. Beneath the delta surface, groundwater stored in the soil strata fluctuates with river tides, resulting in pressure variations within the soil strata. Here, we introduce a novel ultra‐weak fiber‐optic instrument to test the hypothesis that tide‐induced groundwater level variations induce periodic soil stratum deformation. Using borehole deployments ranging over 70 m in the subsurface of the Yangtze Delta, we observe semidiurnal and spring–neap cycles of soil stratum deformation and reveal its dependence on lithology and depth. This allows us to coin the new term “soil stratum tide,” defined as the periodic deformation of soil strata in response to pressure fluctuations induced by tides in open water. High‐accuracy monitoring of the breathing of tidal deltas enables calibrating Earth observation systems, analysis of delta subsidence, and safeguarding of infrastructure jeopardized by soil stratum deformation.
Simultaneous Mesoscale Polar Cusp Field‐Aligned Currents Measured on Mid‐ and Low‐Altitude Satellites
Authors: Dong X.‐C. , Dunlop M. W. , Xiao C. , Wei D. , Wang T.‐Y. , Zhao J.‐S. 
Published: December 2022

AbstractUsing a conjunction of Cluster in the mid‐altitude dayside magnetosphere and Swarm in the low‐altitude ionosphere, we show, by employing multi‐spacecraft analysis, that matched, strong magnetic perturbations and the corresponding mesoscale field‐aligned current (FAC) structures are measured in the high latitude polar cusp region during the 7 October 2015 storm. Two pairs of opposite (positive/negative) FACs are observed by both Cluster and Swarm, which may relate to pulsed magnetic reconnection at the dayside magnetopause. Furthermore, the current intensity of these matched FACs decreases from high to low latitude, consistent with the time elapsed since reconnection. Corresponding geomagnetic disturbances are also observed by ground stations. Our observations provide direct evidence for the coupling of mesoscale FACs between the magnetosphere, ionosphere and ground in the polar cusp region, where the signatures are driven in this case by conditions suitable for inducing reconnection.
Magnetic Fields and Plasma Motions in a Hybrid Martian Magnetosphere
Authors: Dubinin E. , Fraenz M. , Pätzold M. , Tellmann S. , Modolo R. , DiBraccio G. , McFadden J. , Espley J. 
Published: December 2022

AbstractThe Martian magnetosphere contains elements of induced and intrinsic origin. To display them one must use different coordinate systems. Although the solar‐electric coordinate system (Mars Solar Electric [MSE]) adequately describes the main features of the induced magnetosphere, it removes/suppresses aspects caused by the crustal magnetic sources while rotating the spacecraft position to the MSE‐coordinate system and averaging over many orbits. On the other hand, to observe effects of the crustal field one should use the solar orbital coordinates (Mars Solar Orbital [MSO]). To find a compromise and keeping in mind that the most probable value of the clock angle of the interplanetary magnetic field (IMF) on the Mars orbit is ∼90° we can consider separately cases with positive and negative By components of the IMF. It is shown that dynamics of ion fluxes in the distant regions of the magnetosphere is mainly controlled by induced features. However, reconnection of the draping IMF with crustal field leads to a twisting of the classical draping configuration. Despite of the very intricate local geometry of the crustal field, the low‐order harmonics of the magnetic field and mainly the dipole component determine the reconnection sites, at least, statistically for many Mars rotations. For different signs of the By component of the IMF these sites occur either in the +Y‐MSO or −Y‐MSO hemispheres. As a result, statistically the magnetosphere of Mars looks like a hybrid magnetosphere formed during the solar wind interaction with the obstacle which simultaneously contains an extended ionosphere and a weak dipole magnetic field.
SANS: Publicly Available Daily Multi‐Scale Seismic Ambient Noise Source Maps
Authors: Igel Jonas K. H. , Bowden Daniel C. , Fichtner Andreas 
Published: December 2022

AbstractSeismic ambient noise sources have received increased attention recently, creating new possibilities to study the Earth's subsurface and the atmosphere‐ocean‐solid Earth coupling. In efforts to locate such noise sources using nonlinear finite‐frequency inversions, methodological developments such as pre‐computed wavefields and spatially variable grids were necessary. These make inversions feasible for the secondary microseismic sources in a frequency range up to 0.2 Hz on a daily basis. By obtaining a starting model for the inversion using Matched Field Processing (MFP) we are able to further steer the inversion toward acceptable global noise source models and improve the final result. Analysis of 1 year of daily inversions shows the seasonal variations of the secondary microseisms and their dependence on the atmosphere‐ocean‐solid Earth coupling due to storm‐induced ocean waves. We present a web framework, seismic ambient noise sources (SANS, sans.ethz.ch), where daily regional‐ to global‐scale SANS maps for the secondary microseisms are made available to the public. This enables the implementation of time‐variable noise source distributions into full‐waveform ambient noise tomography and time‐dependent subsurface monitoring methods. Additionally, it can act as a reference for other studies that locate secondary microseismic sources on a larger scale.
Revisiting Atmospheric Features of Mars Orbiter Laser Altimeter Data Using Machine Learning Algorithms
Authors: Caillé Vincent , Määttänen Anni , Spiga Aymeric , Falletti Lola 
Published: December 2022

AbstractThe Mars Orbiter Laser Altimeter (MOLA) instrument has been drawing a map of Mars' topography between September 1997 and June 2001. It has also been able to observe clouds during the mission duration, providing data for the low Martian atmosphere for nearly 1.5 Mars years. The Mars Global Surveyor, which carried MOLA, also carried two other instruments that also observed clouds during the same time period (the Mars Orbiter Camera and the Thermal Emission Spectrometer). Combining observations from these three data sets could provide a complete recap of most atmospheric structures during MY24 and MY25. However, previous studies of MOLA data set often had to use stringent detection criteria. Using machine learning clustering methods, we end up finding way more atmospheric returns. Our results are presented in the form of an atmospheric features catalog that we then use to compare MOLA observations with Mars Orbiter Camera and Thermal Emission Spectrometer results, but also with more recent missions. We study the development of recurrent phenomenon in the Martian atmosphere, like the aphelion cloud belt or the south polar hood, but also spontaneous events such as regional dust storms. Methods could be tuned even more finely by using more complex clustering methods or deep learning algorithms to clearly distinguish atmospheric structures.
Cryogenic Sulfuric Weathering and Challenges for Preserving Iron‐Rich Olivine on Cold and Icy Mars
Authors: Yu Xiao‐Wen , Zhao Yu‐Yan Sara , Wu Yanxue , Qi Chao , Li Dongdong , Lin Honglei , Yang Shiling , Liu Jianzhong , Li Xiongyao 
Published: December 2022

AbstractIron‐rich olivine (Fe contents ≥20%) is widely distributed on Mars, but its dissolution rates, weathering products, and particularly Fe behavior under Mars‐relevant conditions are largely unconstrained. Here, we experimentally investigate the dissolution of synthetic Fe‐rich olivine (Fa29 to Fa100; grain size ∼53 μm) for a water‐limited cryogenic sulfuric weathering scenario at 233 K. Fayalite (Fa) and forsterite (Fo) in Fo‐dominant olivine dissolve simultaneously, whereas fayalite dissolution in Fa‐dominant olivine is hindered. Primary alteration products are FeII‐Mg‐sulfates and amorphous silica with minor ferric sulfates and gypsum. Freezing and acidic conditions enhance Fe mobility and subsequent Fe cycling on Mars. The lifetime of Fe‐rich olivine is two to three orders of magnitude shorter than that of Mg‐rich San Carlos olivine. The cryogenic sulfuric weathering scenario greatly challenges the survival of Fe‐rich olivine. Spatial and temporal restrictions for acid‐olivine interactions or insufficient sulfur supply relative to olivine are essential to preserving olivine throughout cold and icy ancient Mars.
About the Propagation of RSDN‐20 “Alpha” Signals in the Earth‐Ionosphere Waveguide During Geomagnetic Disturbances
Authors: Akhmetov O. I. , Belakhovsky V. B. , Mingalev I. V. , Mingalev O. V. , Larchenko A. V. , Suvorova Z. V. 
Published: December 2022

AbstractThe paper presents the results of the modeling of VLF radio waves propagation in horizontally inhomogeneous region of the high‐latitude Earth‐ionosphere waveguide during different types of the geomagnetic disturbances. The frequencies of the model source of signal correspond to the frequencies of the long‐distance navigation radio system RSDN‐20 “Alpha” constantly broadcasting in the VLF range in the Russian Federation. It is considered the geomagnetic storm on 24 January 2012 and geomagnetic substorm on 11 December 2015. Electron density profiles and collision rates of electrons with neutrals are taken from the measurements of EISCAT radar in Tromso and EISCAT 42m radar on Svalbard. The numerical experiments were conducted with a highly horizontally inhomogeneous electron density in the ionosphere. It is shown that the amplitudes and phases of the VLF signals at these frequencies show a noticeable reaction to changes in the ionospheric parameters during the considered geomagnetic disturbances. Calculations show that changes in amplitude of RSDN‐20 “Alpha” signals caused by the action of the Earth's magnetic field and horizontal inhomogeneities depend on the direction of signal propagation relative to the Earth's magnetic field vector and cannot be reversed if the direction of propagation changes to the opposite. The results of the numerical experiment were compared with the corresponding characteristics of the RSDN‐20 signals calculated from the observations of electromagnetic signals at the Lovozero observatory for the case on 11 December 2015.
Quantification and Restoration of the Pre‐Drift Extension Across the NE Atlantic Conjugate Margins During the Mid‐Permian‐Early Cenozoic Multi‐Rifting Phases
Authors: Abdelmalak Mansour M. , Gac Sébastien , Faleide Jan Inge , Shephard Grace E. , Tsikalas Filippos , Polteau Stéphane , Zastrozhnov Dmitry , Torsvik Trond H. 
Published: December 2022

AbstractThe formation of the NE Atlantic conjugate margins is the result of multiple rifting phases spanning from the Late Paleozoic and culminating in the early Eocene when breakup was accompanied with intense magmatic activity. The pre‐breakup configuration of the NE Atlantic continental margins is controlled by crustal extension, magmatism, and sub‐lithospheric processes, all of which need to be quantified for the pre‐breakup architecture to be restored. Key parameters that need to be extracted from the analysis of crustal structures and sediment record include stretching factors, timing of rifting phases, and nature of the deep crustal structures. The aim of this study is to quantify the pre‐drift extension of the NE Atlantic conjugate margins using interpreted crustal structure and forward basin modeling. We use a set of eight 2D conjugate crustal transects and corresponding stratigraphic models, constrained from an integrated analysis of 2D and 3D seismic and well data. The geometry and thickness of the present‐day crust is compared to a reference thickness which has experienced limited or no crustal extension since Permian time allowing the quantification of crustal stretching. Based on the eight conjugate crustal transects, the total pre‐drift extension is estimated to range between 181 and 390 km with an average of 270–295 km. These estimates are supported by the results of forward basin modeling, which predict total extension between 173 and 325 km, averaging 264 km. The cumulative pre‐drift extension estimates derived from basin modeling are in turn used to calculate the incremental crustal stretching factors at each of the three main rifting phases between the conjugate Greenland‐Norwegian margins. The mid‐Permian early Triassic rifting phase represents 32% of the total extension, while the equivalent values are 41% for the mid‐Jurassic to mid‐Cretaceous and 27% for the Late Cretaceous‐Paleocene rifting phases. These values are used to establish and present at first, a full‐fit palinspastic plate kinematic model for the NE Atlantic since the mid‐Permian and will be the base for future work on more elaborated models in order to build accurate paleogeographic and tectonic maps.