bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elevated Post K‐Pg Export Productivity in the Gulf of Mexico and Caribbean
Authors: Lowery Christopher M. , Bralower Timothy J. 
Published: September 2022

AbstractThe global heterogeneity in export productivity after the Cretaceous‐Paleogene (K‐Pg) mass extinction is well documented, with some sites showing no change on geologic timescales, some demonstrating sustained decline, and a few showing a somewhat surprising increase. However, observational data come from sites so widespread that a key outstanding question is the geographic scale of changes in export productivity, and whether similar environments (e.g., open ocean gyres) responded similarly or whether heterogeneity is unrelated to environment. To address this, we developed three new Ba/Ti export productivity records from sites in the Gulf of Mexico and Caribbean which, combined with published data from a fourth site in the Chicxulub Crater itself, allow us to reconstruct regional changes in post K‐Pg export productivity for the first time. We find that, on a regional scale, export productivity change was homogenous, with all four sites showing a ∼300 Kyr period of elevated export production just after the boundary, followed by a longer period of decline. Interestingly, this interval of elevated export production appears to coincide with the post K‐Pg global micrite layer, which is thought to at least partially have been produced by blooms of carbonate‐producing cyanobacteria and other picophytoplankton. Global comparison of sites shows that elevated export productivity appears to have been most common in oligotrophic gyres, which suggests that changing plankton ecology evidenced by the micrite layer altered the biological pump, leading to a temporary increase in export production in these settings.
Predictive Soft Computing Methods for Building Digital Rock Models Verified by Positron Emission Tomography Experiments
Authors: Ebadi Mohammad , Armstrong Ryan T. , Mostaghimi Peyman , Wang Ying Da , Alqahtani Naif , Amirian Tammy , James Lesley Anne , Parmar Arvind , Zahra David , Hamze Hasar , Koroteev Dmitry 
Published: September 2022

AbstractThe influence of core‐scale heterogeneity on continuum‐scale flow and laboratory measurements are not well understood. To address this issue, we propose a fully automated workflow based on soft computing to characterize the heterogeneous flow properties of cores for predictive continuum‐scale models. While the proposed AI‐based workflow inherently has no trained knowledge of rock petrophysical properties, our results demonstrate that image features and morphological properties provide sufficient measures for petrophysical classification. Micro X‐ray computed tomography (μxCT) image features were extracted from full core plug images by using a Convolutional Neural Network and Minkowski functional measurements. The features were then classified into specific classes using Principal Component Analysis followed by K‐means clustering. Next, the petrophysical properties of each class were evaluated using pore‐scale simulations to substantiate that unique classes were identified. The μxCT image was then up‐scaled to a continuum‐scale grid based on the defined classes. Last, simulation results were evaluated against real‐time flooding data monitored by Positron Emission Tomography. Both homogeneous sandstone and heterogeneous carbonate were tested. Simulation and experimental saturation profiles compared well, demonstrating that the workflow provided high‐fidelity characterization. Overall, we provided a novel workflow to build digital rock models in a fully automated way to better understand the impacts of heterogeneity on flow.
Simplified Automatic Atmospheric Correction for THEMIS Infrared Data
Authors: Ye Cheng , Pan Cong , Edwards Christopher S. , Rogers A. Deanne 
Published: September 2022

AbstractThermal infrared spectral data from the Thermal Emission Imaging System (THEMIS) on Mars Odyssey can provide diagnostic information to characterize Martian surface compositions. Accurately isolating the atmospheric contribution from the thermal radiance of THEMIS data is essential for surface mineralogy analysis. In this work, we present improved semi‐automatic and fully automated tools to simplify the traditional atmospheric correction method for THEMIS data. Both methods use the Thermal Emission Spectrometer surface emissivity data but in different ways. These two methods are applied to several locations that have been well documented in previous studies, to assess their capability of determining surface spectral features. The fully automatic method demonstrates its simplicity, viability, and robustness by which more consistent results have been generated for the same area across multiple THEMIS images and for areas with large topographic gradients. The tools developed in this work will broaden the utilization of THEMIS infrared spectral data to the wider planetary science community.
Using ARMAX Models to Determine the Drivers of 40–150 keV GOES Electron Fluxes
Authors: Simms L. E. , Ganushkina N. Yu. , van de Kamp M. , Liemohn M. W. , Dubyagin S. 
Published: September 2022

AbstractWe investigate the drivers of 40–150 keV hourly electron flux at geostationary orbit (GOES 13) using autoregressive moving average transfer functions (ARMAX) multiple regression models which remove the confounding effect of diurnal cyclicity and allow assessment of each parameter independently. By taking logs of the variables, we create nonlinear models. While many factors show high correlation with flux in single variable analysis (substorms, ULF waves, solar wind velocity (V), pressure (P), number density (N) and electric field (Ey), IMF Bz, Kp, and SymH), ARMAX models show substorms are the dominant influence at 40–75 keV and over 20–12 MLT, with little difference seen between disturbed and quiet periods. The Ey influence is positive post‐midnight, negative post‐noon. Pressure shows a negative influence, strongest at 150 keV. ULF waves are a more modest influence than suggested by single variable correlation. Kp and SymH show little effect when other variables are included. Using path analysis, we calculate the summed direct and indirect influences through the driving of intermediate parameters. Pressure shows a summed direct and indirect influence nearly half that of the direct substorm effect. N, V, and Bz, as indirect drivers, are equally influential. While simple correlation or neural networks can be used for flux prediction, neither can effectively identify drivers. Instead, consideration of physical influences, removing cycles that artificially inflate correlations, and controlling the effects of other parameters gives a clearer picture of which are most influential in this system.
On the Moments of Probability Distribution Function of Amplitude Scintillation in the Polar Region
Authors: Meziane K. , Hamza A. M. , Jayachandran P. T. 
Published: September 2022

AbstractThe distortions seen in the Global Navigation Satellite Systems radio signal caused by ionospheric irregularities in the polar region are examined through the lens of probability distributions of fluctuations in the recorded scintillation signals. The first four moments of the probability distribution function (PDF) of the amplitude scintillation are computed and analyzed for 106 events collected at Pond Inlet station [Magnetic Coordinates = (80.0°N, 2.6°E)]. As a starting point, the background variation level is investigated using similar computations carried out with about 400 30‐s window segments. The resulting distribution for the skewness (third moment) and the kurtosis (fourth moment) strongly indicate that the background fluctuations are nearly Gaussian; given the computed variances, the Rayleigh distribution hypothesis is ruled out. In the case where scintillation is present, we found that the skewness distribution nearly overlaps with the background while the excess kurtosis strongly indicates a departure from normality. More precisely, the PDF appear mostly symmetric and leptokurtic (positive kurtosis K) and exhibit, in some cases, significant flatness (K ∼ 1). These results reveal that the analyzed scintillations are statistically consistent with stationarity and therefore vanishing skewness. Moreover, the empirical moments are compared with those derived from probability densities referred in the literature regarding scintillations. We have found that none of the log‐normal, Nakagami, Rician and α–μ distributions account for the analyzed data. The generalized Gaussian distribution with a shape parameter 1 < β < 2 seems the most probable and the most adequate to account for the results.
Multi‐Fluid MHD Simulations of Europa's Plasma Interaction: Effects of Variation in Europa's Atmosphere
Authors: Harris Camilla D. K. , Jia Xianzhe , Slavin James A. 
Published: September 2022

AbstractEuropa's plasma interaction is inextricably coupled to its O2 atmosphere by the chemical processes that generate plasma from the atmosphere and the sputtering of magnetospheric plasma against Europa's ice to generate O2. Observations of Europa's atmosphere admit a range of possible densities and spatial distributions (Hall et al., 1998, https://doi.org/10.1086/305604). To better understand this system, we must characterize how different possible configurations of the atmosphere affect the 3D magnetic fields and bulk plasma properties near Europa. To accomplish this, we conducted a parameter study using a multi‐fluid magnetohydrodynamic model for Europa's plasma interaction (Harris et al., 2021, https://doi.org/10.1029/2020ja028888). We varied parameters of Europa's atmosphere, as well as the conditions of Jupiter's magnetosphere, over 18 simulations. As the scale height and density of Europa's atmosphere increase, the extent and density of the ionosphere increase as well, generating strong magnetic fields that shield Europa's surface from impinging plasma on the trailing hemisphere. We also calculate the precipitation rate of magnetospheric plasma onto Europa's surface. As the O2 column density increased from (1–2.5) × 1014 cm−2, the precipitation rate decreased sharply then leveled off at 2 × 1024 ions/s for simulations with low magnetospheric plasma density and 6.4 × 1024 ions/s for simulations with high magnetospheric plasma density. These results indicate that the coupling between Europa's plasma populations and its atmosphere leads to feedback that limits increases in the ionosphere density.
Spectral Properties of Whistler‐Mode Waves in the Vicinity of the Moon: A Statistical Study With ARTEMIS
Authors: Sawaguchi W. , Harada Y. , Kurita S. , Nakamura S. 
Published: September 2022

AbstractWe present statistical analyses of whistler‐mode waves observed by Acceleration, Reconnection, and Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS). Although some observations showed that the lunar whistler‐mode waves have similarities to the terrestrial chorus emissions, it remains unknown whether the banded structure typically seen in chorus is common to the lunar waves. In this study, we automatically detected whistler‐mode waves from 9 years of ARTEMIS data and classified them into four types of spectral shapes: lower band only, upper band only, banded, and no‐gap. We first show that a magnetic connection to the lunar surface is a dominant factor in the wave generation. The occurrence rate of whistler‐mode waves is 10 times larger on the magnetic field line connected to the Moon. Then we compared the field line connected events according to the position of the Moon and the condition of the field‐line foot point (day/night and existence of magnetic anomalies). The results show that (a) almost no banded event is observed in any circumstances, suggesting that generation mechanisms for the two band structure of the terrestrial chorus are largely ineffective around the Moon and (b) the wave occurrence rate depends on the foot point conditions, presumably affected by electrostatic/magnetic reflections deforming the velocity distribution of the resonant electrons. Thus, our results provide implications for the two band structure formation and new insights into fundamental processes of the Moon‐plasma interaction.
Mechanisms for Zonal Mean Wind Responses in the Thermosphere to Doubled CO2 Concentration
Authors: Kogure Masaru , Liu Huixin , Tao Chihiro 
Published: September 2022

AbstractWe explored mechanisms for the thermospheric zonal mean wind responses to doubled CO2 concentration through investigating the zonal mean momentum balance in the thermosphere using GAIA model simulations in June. The analysis shows that ion drag, molecular viscosity, and meridional pressure gradient force vary 3–20 times more than the other forces due to the doubled CO2 concentration. The three forces strongly attenuate each other; consequently, the increase in zonal mean zonal ion drag dominantly strengthens the southward wind (∼15 ms−1 at maximum) in the northern (summer) hemisphere and latitudes north of 35S. This strengthened ion drag was attributed to increased ion density/relative velocity between ions and neutral particles in the northern/southern hemisphere. Southward of 35, the zonal pressure gradient force and the meridional advection of zonal wind strengthen the southward wind by 4–12 ms−1 in total. On the other hand, the zonal wind is mainly altered by increased meridional pressure gradient force (∼15 ms−1 at maximum) caused by a latitudinally asymmetric response of the thermosphere density to increasing CO2 concentration. Our results suggest that the increased ion density in the northern hemisphere is the underlying trigger for the wind responses to increasing CO2 concentration. Furthermore, we show that the meridional advection was mainly (∼70%) due to that of the DW1 tidal component.
Electron Heat Fluxes Generated by Intense Whistler Waves at the Upper Ionospheric Altitudes
Authors: Khazanov George V. , Ma Qianli , Chu Mike 
Published: September 2022

AbstractMagnetospheric whistler waves, chorus and hiss, can't provide the resonance heating of the core electron plasma population. However, these whistler‐mode branches, can implicitly participate in the heating processes of the core plasma thermal electron population by triggering the electron precipitation over a broad energy range from the magnetosphere and subsequent atmospheric ionization processes leading to the production of superthermal electron population. These superthermal electrons play a large role in the magnetosphere‐ionosphere‐atmosphere energy interplay with participation of both magnetically conjugate hemispheres, and their Coulomb interaction with background magnetospheric thermal electrons. Using strong hiss and chorus wave events measured by the Van Allen Probes and SuperThermal Electron Transport code, we evaluate the formation of electron heat fluxes at the upper ionospheric altitudes and discuss their consequences on the formation of electron temperature. It is found that chorus and hiss waves that initiate the precipitation of magnetospheric electrons with energies below 30 keV and the follow‐up production of secondary electrons play an important role in the energy balance of ionosphere‐magnetosphere system.
Sub‐Decadal Volcanic Tsunamis Due To Submarine Trapdoor Faulting at Sumisu Caldera in the Izu–Bonin Arc
Authors: Sandanbata Osamu , Watada Shingo , Satake Kenji , Kanamori Hiroo , Rivera Luis , Zhan Zhongwen 
Published: September 2022

AbstractThe main cause of tsunamis is large subduction zone earthquakes with seismic magnitudes Mw > 7, but submarine volcanic processes can also generate tsunamis. At the submarine Sumisu caldera in the Izu–Bonin arc, moderate‐sized earthquakes with Mw < 6 occur almost once a decade and cause meter‐scale tsunamis. The source mechanism of the volcanic earthquakes is poorly understood. Here we use tsunami and seismic data from the recent 2015 event to show that abrupt uplift of the submarine caldera, with a large brittle rupture of the ring fault system due to overpressure in its magma reservoir, caused the earthquake and tsunami. This submarine trapdoor faulting mechanism can efficiently generate tsunamis due to large vertical seafloor displacements, but it inefficiently radiates long‐period seismic waves. Similar seismic radiation patterns and tsunami waveforms due to repeated earthquakes indicate that continuous magma supply into the caldera induces quasi‐regular trapdoor faulting. This mechanism of tsunami generation by submarine trapdoor faulting underscores the need to monitor submarine calderas for robust assessment of tsunami hazards.
Strong Modulation of Human‐Activity‐Induced Weekend Effect in Urban Heat Island by Surface Morphology and Weather Conditions
Authors: Wang Chunli , Zhan Wenfeng , Liu Xue , Liu Zihan , Miao Shiqi , Du Huilin , Li Jiufeng , Wang Chenguang , Li Long , Yue Wenze 
Published: September 2022

AbstractThe weekend effect of the canopy urban heat island (UHI) has been long recognized. However, how the UHI weekend effect (UWE) varies with the hour of day and season of year is still unclear; it remains largely unknown on how the UWE is regulated by various controls. To address these knowledge gaps, here we took Beijing, China as an example and investigated the detailed spatiotemporal UWE patterns and the major regulators with a 3‐year data set of in‐situ surface air temperatures. Our results indicate that the annual ΔIc (the UHI intensity difference on weekends and weekdays) is stronger at night (−0.13 ± 0.12 K; mean ± 1 STD) than during the day (−0.05 ± 0.10 K); at the seasonal scale, ΔIc reaches the strongest in winter (−0.14 K) and the weakest in summer (−0.05 K). The ΔIc is strongly regulated by anthropogenic heat flux (AHF), evidenced by a quasi‐synchronous diurnal pattern between ΔIc and ΔAHF (i.e., the AHF difference between weekends and weekdays). The nighttime ΔIc is intensely modulated by urban morphology, with a stronger modulation by the landscape shape index than by the distance of the station from the urban center. Weather conditions also modulate the ΔIc, with the ΔIc weakening with the increase of cloud coverage and wind speed level. We consider these findings deepen our understanding of the weekly rhythms of UHI as well as the underlying modulators.
Characteristics of Latent Heating Rate From GPM and Convective Gravity Wave Momentum Flux Calculated Using the GPM Data
Authors: Lee Hyun‐Kyu , Kang Min‐Jee , Chun Hye‐Yeong , Kim Donghyeck , Shin Dong‐Bin 
Published: September 2022

AbstractParameterizations of convective gravity‐wave (CGW) drag (CGWD) require cloud information as input parameters. As cloud information provided from reanalyses includes some uncertainties, observed cloud information is required for better representation of CGWs. For this, characteristics of the latent heating rate (LHR) based on the Global Precipitation Measurement (GPM) satellite over 6 yr (June 2014 to May 2020) are investigated, and the CGW momentum flux and CGWD based on an offline CGWD parameterization are calculated using the GPM‐LHR and the Modern‐Era Retrospective Analysis for Research and Applications, Version 2 (MERRA‐2) background variables. Additionally, they are compared with those using LHR afforded by MERRA‐2. The averaged cloud‐bottom height is lower than that from MERRA but the cloud top height is similar for the both data, yielding deeper clouds from GPM that can generate more high phase‐speed components of CGWs. The column‐maximum heating rate, which is an input of the CGW momentum flux, of GPM‐LHR is maximal near the equator and the secondary maximum locates in the winter hemisphere storm tracks. The maximum of the cloud top momentum flux (CTMF) of CGWs locates in the winter hemisphere storm tracks, with the GPM‐CTMF being much larger than MERRA‐CTMF, as extreme convective events occur more frequently in GPM. In the equatorial region above z = 40 km, the GPM‐CGWD is significantly larger because high phase‐speed components of CGWs that survive up to the upper stratosphere are abundant for GPM‐CTMF, and this will contribute to drive more realistic semi‐annual oscillation.
ASL-BIDS, the brain imaging data structure extension for arterial spin labeling
Authors: Clement Patricia , Castellaro Marco , Okell Thomas W. , Thomas David L. , Vandemaele Pieter , Elgayar Sara , Oliver-Taylor Aaron , Kirk Thomas , Woods Joseph G. , Vos Sjoerd B. , Kuijer Joost P. A. , Achten Eric , van Osch Matthias J. P. ,   BIDS maintainers, Appelhoff Stefan , Blair Ross , Feingold Franklin , Gau Rémi , Markiewicz Christopher J. , Salo Taylor , Detre John A. , Lu Hanzhang , Alsop David C. , Chappell Michael A. , Hernandez-Garcia Luis , Petr Jan , Mutsaerts Henk J. M. M. 
Published: September 2022

AbstractArterial spin labeling (ASL) is a non-invasive MRI technique that allows for quantitative measurement of cerebral perfusion. Incomplete or inaccurate reporting of acquisition parameters complicates quantification, analysis, and sharing of ASL data, particularly for studies across multiple sites, platforms, and ASL methods. There is a strong need for standardization of ASL data storage, including acquisition metadata. Recently, ASL-BIDS, the BIDS extension for ASL, was developed and released in BIDS 1.5.0. This manuscript provides an overview of the development and design choices of this first ASL-BIDS extension, which is mainly aimed at clinical ASL applications. Discussed are the structure of the ASL data, focussing on storage order of the ASL time series and implementation of calibration approaches, unit scaling, ASL-related BIDS fields, and storage of the labeling plane information. Additionally, an overview of ASL-BIDS compatible conversion and ASL analysis software and ASL example datasets in BIDS format is provided. We anticipate that large-scale adoption of ASL-BIDS will improve the reproducibility of ASL research.
Task prioritization modulates alpha, theta and beta EEG dynamics reflecting proactive cognitive control
Authors: Liegel Nathalie , Schneider Daniel , Wascher Edmund , Arnau Stefan 
Published: September 2022

AbstractMost neuroscientific studies investigating mental effort apply unspecific effort allocation paradigms. In contrast, the present EEG study targets specific effort allocation during task prioritization. Twenty-eight participants performed a cued number classification task during the retention interval of a working memory task including retrospective cues. One of two possible number classifications was done per trial. Each trial started with a cue indicating which of the two tasks would be more important in the upcoming trial. Subjects were told to engage in both tasks, but to concentrate on the important one. Feedback given at the end of each trial was calculated based on task performance, with scores obtained from the relevant task being tripled. Participants performed significantly better in either task when it was important compared to when not. Task prioritization modulates theta, alpha and beta oscillations, predominantly during task preparation. Multivariate pattern analysis revealed that the exact type of the two possible number classifications was decodable, however, decoding accuracy did not depend on task importance. Hemispheric alpha power asymmetries indicating attentional orienting between working memory representations also did not depend on task importance. The findings suggest that task prioritization primarily affects proactive cognitive control on a superordinate level.