bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Drivers of the Martian Bow Shock Location: A Statistical Analysis of Mars Atmosphere and Volatile EvolutioN and Mars Express Observations
Authors: Garnier P. , Jacquey C. , Gendre X. , Génot V. , Mazelle C. , Fang X. , Gruesbeck J. R. , Sánchez‐Cano B. , Halekas J. S. 
Published: May 2022

AbstractThe Martian interaction with the solar wind leads to the formation of a bow shock upstream of the planet. The shock dynamics appear complex, due to the combined influence of external and internal drivers. The extreme ultraviolet fluxes and magnetosonic Mach number are known major drivers of the shock location, while the influence of other possible drivers is less constrained or unknown such as crustal magnetic fields, solar wind dynamic pressure, or the Interplanetary Magnetic Field (IMF) intensity, and orientation. In this study, we compare the influence of the main drivers of the Martian shock location, based on several methods and published datasets from Mars Express (MEX) and Mars Atmosphere Volatile EvolutioN (MAVEN) missions. We include here the influence of the crustal fields, extreme ultraviolet fluxes, solar wind dynamic pressure, as well as (for MAVEN, thanks to magnetic field measurements) magnetosonic Mach number and Interplanetary Magnetic Field parameters (intensity and orientation angles). The bias due to the cross‐correlations among the possible drivers is investigated with a partial correlations analysis. Several model selection methods (Akaike Information Criterion and Least Absolute Shrinkage Selection Operator regression) are also used to rank the relative importance of the physical parameters. We conclude that the major drivers of the shock location are extreme ultraviolet fluxes and magnetosonic Mach number, while crustal fields and solar wind dynamic pressure are secondary drivers at a similar level. The IMF orientation also plays a significant role, with larger distances for perpendicular shocks rather than parallel shocks.
Improved Climate Simulation by Using a Double‐Plume Convection Scheme in a Global Model
Authors: Li Xiaohan , Zhang Yi , Peng Xindong , Chu Wenchao , Lin Yanluan , Li Jian 
Published: May 2022

AbstractConvective parameterization can drastically regulate the mean climate and tropical transient activity of a General circulation model (GCM). In this study, the physics suite of the NCAR Community Atmosphere Model, version 5 (CAM5) was first ported to the Global‐to‐Regional Integrated Forecast System model. Then, the original convective parameterization of CAM5—with a separate representation of deep convection Zhang–Mcfarlane (ZM) and shallow convection University of Washington (UW)—was replaced by a double‐plume (DP) scheme. This DP scheme adopts a quasi‐unified representation of shallow and deep convection within a single framework. Results demonstrate that the new scheme brings about several improvements in the modeled climate. The differences in the trigger and closure assumptions, lateral mixing rate, and cloud model for the deep convection result in systematic regional differences in the simulated precipitation pattern, cloud vertical structure, and the associated radiative forcing. Compared with ZM‐UW, DP reduces the biases in precipitation over the Indian Ocean, ameliorates the “high‐frequency and low‐intensity” problem of tropical precipitation, and leads to an improved representation of tropical variability, including the Madden–Julian Oscillation. Double‐plume reduces low clouds and increases high clouds in the tropics, due to its internal parallel‐split convective processes and smaller cumulus cloud fraction. Discussions related to parametric tuning of convective parameterization are also presented.
The Geophysical Environment of (486958) Arrokoth—A Small Kuiper Belt Object Explored by New Horizons
Authors: Keane James T. , Porter Simon B. , Beyer Ross A. , Umurhan Orkan M. , McKinnon William B. , Moore Jeffrey M. , Spencer John R. , Stern S. Alan , Bierson Carver J. , Binzel Richard P. , Hamilton Douglas P. , Lisse Carey M. , Mao Xiaochen , Protopapa Silvia , Schenk Paul M. , Showalter Mark R. , Stansberry John A. , White Oliver L. , Verbiscer Anne J. , Parker Joel W. , Olkin Catherine B. , Weaver Harold A. , Singer Kelsi N. 
Published: May 2022

AbstractNASA's New Horizons mission performed the first flyby of a small Kuiper Belt Object (KBO), (486958) Arrokoth on 1 January 2019. The fast flyby revealed a fascinating, flattened, contact binary replete with a variety of unexpected geologic terrains. However, the irregular shape and constraints imposed by the fast flyby makes it a challenge to understand these features. Here we use the latest New Horizons shape models of Arrokoth to investigate its geophysical environment, including its surface slopes, gravity field, and moments of inertia—which are critical context for understanding Arrokoth's formation, evolution, and peculiar geology. We find that Arrokoth's surface features have a complicated relationship to its geophysical environment. For example, bright material tends to be concentrated in geopotential lows (like the neck), consistent with mass wasting—however, this trend is not consistently observed across Arrokoth. Mass wasting may naturally explain some aspects of Arrokoth's geology, but the actual dynamics of material transport may be complicated owing to Arrokoth's unique shape, spin‐rate, and inferred density. While New Horizons's fast and distant flyby precluded directly measuring Arrokoth's mass, we used techniques previously pioneered for comets and asteroids to infer its density. We find that Arrokoth has a low bulk density of ρ = 235 kg/m3 (1σ range: 155–600 kg/m3). This density is low compared to previously explored small bodies, but is comparable to comets, select binary KBOs, and the ring‐moons of Saturn. This low density may be a critical data‐point for understanding the formation of planetesimals at the dawn of the Solar System.
Constraints on the Emplacement of Martian Nakhlite Igneous Rocks and Their Source Volcano From Advanced Micro‐Petrofabric Analysis
Authors: Griffin S. , Daly L. , Keller T. , Piazolo S. , Forman L. V. , Lee M. R. , Baumgartner R. J. , Trimby P. W. , Benedix G. K. , Irving A. J. , Hoefnagels B. 
Published: May 2022

AbstractThe Martian nakhlite meteorites, which represent multiple events that belong to a single magma source region represent a key opportunity to study the evolution of Martian petrogenesis. Here 16 of the 26 identified nakhlite specimens are studied using coupled electron backscatter diffraction (EBSD) and emplacement end‐member calculations. EBSD was used to determine shape preferred orientation of contained augite (high Ca‐clinopyroxene) phenocrysts by considering their crystallographic preferred orientation (CPO). Parameters derived from EBSD, and energy dispersive X‐ray spectroscopy spectra were used in basic emplacement models to assess their dominant mechanism against three end‐member scenarios: thermal diffusion, crystal settling, and crystal convection. Results from CPO analyses indicate low intensity weak‐moderate CPO. In all samples, a consistent foliation within the <001> axes of augite are observed typically coupled with a weaker lineation CPO in one of the other crystallographic axes. These CPO results agree best with crystal settling being the dominant emplacement mechanism for the nakhlites. Modeled crystal settling results identify two distinguishable groups outside of the model's resolution indicating the presence of secondary emplacement mechanisms. Comparison of the two identified groups against CPO, geochemical, and age parameters indicate random variability between individual meteorites. Therefore, coupled CPO and emplacement modeling results identify an overarching characteristic of a dominant crystal settling emplacement mechanism for the nakhlite source volcano despite exhibiting random variation with each discharge through time.
A New Global Ionospheric Electron Density Model Based on Grid Modeling Method
Authors: Le Huijun , Han Tingwei , Li Qiaoling , Liu Libo , Chen Yiding , Zhang Hui 
Published: May 2022

AbstractBased on nearly 4.6 million radio occultation (RO) ionospheric profile data from Constellation Observing System for Meteorology, Ionosphere, and Climate satellites in 2006–2020, a global three‐dimensional ionospheric electron density model was constructed with a new concept. The global 3D ionosphere structure was divided into total 338,661 grids with longitude intervals of 10°, latitude intervals of 2°, and height intervals of 5 km. On each grid, the electron density is modeled as a function of solar activity, geomagnetic activity, local time, and season variation using 21 coefficients. Then all grid models are combined to form a global ionospheric model. This method makes full use of all ionospheric electron density data. The spatial resolution of the model is high with 10° in longitude, 2° in latitude, and 5 km in height, which can effectively model the fine ionospheric spatial structure like the longitudinal wavenumber‐4 structure in low latitudes. The model also takes into account the influence of both solar and geomagnetic activities on the ionosphere. At the altitude below the F2 peak, the RO electron density observation suffers from an artificial meridional maximum between the double peaks of the equatorial ionization anomaly, referred hereafter as the three‐peak error. By combining our model with the International Reference Ionospheric electron density results of the E layer below 140 km, the problem of three‐peak error is effectively solved. Compared the with other data sources such as the ZH01 and the ROCSAT‐1, the modeling ability of model in fine spatial structure is verified.
An Interactively Corrected Smoothed Particle Hydrodynamics (IC‐SPH) for Simulating Solute Transport in a Nonuniform Velocity Field
Authors: Jiao Tian , Ye Ming , Jin Menggui , Yang Jing 
Published: May 2022

AbstractThe Smoothed Particle Hydrodynamics (SPH) method is a Lagrangian approach that has been widely used to eliminate numerical dispersion for solving advection‐dispersion equation (ADE) of groundwater solute transport under advection‐dominated situations. It has been found that accuracy of SPH results is severely deteriorated, when particles are irregularly distributed in a model domain with heterogeneous hydraulic conductivity. To resolve this problem, we developed a new approach called Interactively Corrected SPH (IC‐SPH), which is an improved version of the Corrected SPH (C‐SPH) method. IC‐SPH uses an interactively corrected kernel gradient to construct concentration gradients used to solve ADE. This correction is made for each particle by using not only the particle's neighbor particles within the particle's support domain but also the particles within each neighbor particle's support domain. We evaluated IC‐SPH performance in two numerical studies. One considers diffusive transport with an analytical solution, and the other considers advection‐dispersion transport in a heterogeneous field of hydraulic conductivity. For each numerical study, several numerical experiments were conducted using multiple sets of irregularly distributed particles with different levels of particle irregularity. The numerical experiments indicate that, while IC‐SPH is more computationally expensive than SPH and C‐SPH, IC‐SPH produces more accurate ADE solutions, and converges faster to the analytical solution. IC‐SPH is mathematically general, and can be applied to a wide range of problems that require solving ADE.
On Infiltration and Infiltration Characteristic Times
Authors: Rahmati Mehdi , Latorre Borja , Moret‐Fernández David , Lassabatere Laurent , Talebian Nima , Miller Dane , Morbidelli Renato , Iovino Massimo , Bagarello Vincenzo , Neyshabouri Mohammad Reza , Zhao Ying , Vanderborght Jan , Weihermüller Lutz , Jaramillo Rafael Angulo , Or Dani , Th. van Genuchten Martinus , Vereecken Harry 
Published: May 2022

AbstractIn his seminal paper on the solution of the infiltration equation, Philip (1969), https://doi.org/10.1016/b978-1-4831-9936-8.50010-6 proposed a gravity time, tgrav, to estimate practical convergence time and the time domain validity of his infinite time series expansion, TSE, for describing the transient state. The parameter tgrav refers to a point in time where infiltration is dominated equally by capillarity and gravity as derived from the first two (dominant) terms of the TSE. Evidence suggests that applicability of the truncated two‐term equation of Philip has a time limit requiring higher‐order TSE terms to better describe the infiltration process for times exceeding that limit. Since the conceptual definition of tgrav is valid regardless of the infiltration model used, we opted to reformulate tgrav using the analytic implicit model proposed by Parlange et al. (1982), https://doi.org/10.1097/00010694-198206000-00001 valid for all times and related TSE. Our derived gravity times ensure a given accuracy of the approximations describing transient states, while also providing insight about the times needed to reach steady state. In addition to the roles of soil sorptivity (S) and the saturated (Ks) and initial (Ki) hydraulic conductivities, we explored the effects of a soil specific shape parameter β, involved in Parlange's model and related to the type of soil, on the behavior of tgrav. We show that the reformulated tgrav (notably where F(β) is a β‐dependent function) is about three times larger than the classical tgrav given by . The differences between the classical tgrav,Philip and the reformulated tgrav increase for fine‐textured soils, attributed to the time needed to attain steady‐state infiltration and thus i + infiltration for inferring soil hydraulic properties. Results show that the proposed tgrav is a better indicator of time domain validity than tgrav,Philip. For the attainment of steady‐state infiltration, the reformulated tgrav is suitable for coarse‐textured soils. Still neither the reformulated tgrav nor the classical tgrav,Philip are suitable for fine‐textured soils for which tgrav is too conservative and tgrav,Philip too short. Using tgrav will improve predictions of the soil hydraulic parameters (particularly Ks) from infiltration data compared to tgrav,Philip.
Hydrodynamic Analysis of CO2 Migration in Heterogeneous Rocks: Conventional and Micro‐Bubble CO2 Flooding Experiments and Pore‐Scale Numerical Simulations
Authors: Wang Dayong , Fan Jiarui , Xue Ziqiu 
Published: May 2022

AbstractThe hydrodynamics of CO2 flooding determine its capacity and efficiency in CO2 geological storage; however, this is not sufficiently understood. In this study, a medical X‐ray CT was used to visualize CO2 flooding in a Berea sandstone sample, and the migration pattern and distribution of injected CO2 were carefully analyzed in a series of comparison experiments. For conventional flooding, CO2 migrated mostly along the high‐porosity and large‐pore‐size layers, leaving a large area of low‐porosity and small‐pore‐size regions undisplaced. Comparatively, before CO2 broke through, CO2 fingering developed and migrated slowly for micro‐bubble flooding, showing that CO2 micro‐bubbles infiltrated into more regions than the CO2 continuous fluid. After CO2 breakthrough began, the micro‐bubble CO2 continued to enter some previously undisplaced regions; however, this was inconspicuous for conventional flooding. Finally, micro‐bubble flooding increased CO2 saturation by 6.1% over conventional flooding. Compared to conventional flooding, an essential hydrodynamic change by micro‐bubble flooding weakened the resistance of interface tension over CO2 infiltration into the small pores. Accordingly, two types of hydrodynamic models were proposed for conventional and micro‐bubble CO2 flooding, and their simulated pore‐scale CO2 migration results in a cluster of heterogeneous pores were compatible with the aforementioned core‐scale experimental observations. According to these models, both the small sizes and high injection rates of micro‐bubble CO2 were instrumental in enhancing the displacement effect. The filter for micro‐bubble CO2 injection in our experiment achieved even injection of the small CO2 micro‐bubbles at a relatively high rate, ensuring its practical potential in field applications.
Observations of Modulation of Ion Flux in the Coma of Comet 67P/Churyumov‐Gerasimenko
Authors: Goldstein R. , Burch J. L. , Llera K. , Altwegg K. , Rubin M. , Eriksson A. I. , Nilsson H. 
Published: May 2022

AbstractOn 6–8 June 2015, the Ion and Electron Sensor on board Rosetta observed keV‐range water‐group pickup ions arriving from the solar direction. Based on magnetic field intensification and variations, the appearance of the ions was likely to have been caused by a coronal mass ejection. During the 3‐day period when Rosetta was 200 km from the comet, peak ion energy/charge (E/q) varied over a range from 50 eV to 1 keV in concert with neutral gas density variations caused by the rotation of the comet and its variable solar illumination. Thermal ion densities showed the same variations. The neutral density variations provided a unique opportunity to observe the repeated slowing of the solar wind by mass loading caused by charge exchange between energetic water‐group ions and thermal water‐group molecules. Such solar wind slowing was observed previously only by flyby missions that provided single events.
Evidence of Transient Energy and Enstrophy Cascades in Tidal Flows: A Scale to Scale Analysis
Authors: De Leo A. , Stocchino A. 
Published: May 2022

AbstractTidal currents are predominant in coastal areas, causing the generation of vortices at different scales. We reproduce the main process of vortex shedding generated in tidal systems with inlets and channels using a laboratory large‐scale model. A filter‐space technique is implemented to analyze nonlinear energy/enstrophy transfer rates and map out the energy pathways through the flow scales of the measured velocity fields. We provide sound evidence of the transitional character of the energy cascades during a tidal period. The periodic generation and destruction of tidal vortices plays a relevant role in the transition from an inverse to a direct energy cascade within a tidal period. The period‐averaged energy budget shows the coexistence of multiple cascades. Small scales follow a direct energy cascade, whereas a split‐energy cascade is found at intermediate and large scales, where part of the injected energy goes to small scales and part to a larger flow scale.
Signatures of Auroral Potential Structure Extending Through the Near‐Equatorial Inner Magnetosphere
Authors: Imajo S. , Miyoshi Y. , Asamura K. , Shinohara I. , Nosé M. , Shiokawa K. , Kasahara Y. , Kasaba Y. , Matsuoka A. , Kasahara S. , Yokota S. , Keika K. , Hori T. , Shoji M. , Nakamura S. , Teramoto M. 
Published: May 2022

AbstractThe auroral acceleration region plays an important role in the magnetosphere‐ionosphere coupling system. In this study, signatures of an auroral U‐shaped potential structure were found for the first time in the near‐equatorial inner magnetosphere by the Arase satellite at ∼6.0 RE geocentric distance and 11° magnetic latitude. The observed magnetic and electric field variations corresponded to the equatorward motion of the upward field‐aligned current and converging perpendicular electric field. Examining the three‐dimensional velocity distribution function of H+ and O+ ions, we demonstrate that upflowing ion beams were significantly deflected in an east‐west direction with a perpendicular velocity up to ∼80 km/s, which is consistent with the ExB drift velocity. A simple particle drift model with the inferred auroral perpendicular potential presents a new kink‐like drift path of ions from the magnetotail, implying that the auroral potential structure has a great impact on particle dynamics in the near‐earth plasma sheet.
Occurrence Statistics of Horse Collar Aurora
Authors: Bower G. E. , Milan S. E. , Paxton L. J. , Anderson B. J. 
Published: May 2022

AbstractHorse collar aurora (HCA) are an auroral feature where the dawn and dusk sector auroral oval moves polewards and the polar cap becomes teardrop shaped. They form during prolonged periods of northward interplanetary magnetic field (IMF), when the IMF clock angle is small. Their formation has been linked to dual‐lobe reconnection (DLR) closing magnetic flux at the dayside magnetopause. The conditions necessary for DLR are currently not well‐understood therefore understanding HCA statistics will allow DLR to be studied in more detail. We have identified over 600 HCA events between 2010 and 2016 in UV images captured by the Special Sensor Ultraviolet Spectrographic Imager instrument on‐board the Defense Meteorological Satellite Program spacecraft F16, F17 and F18. As expected, there is a clear preference for HCA occurring during northward IMF. We find no clear seasonal dependence in their occurrence, with an average of 8 HCA events per month. The occurrence of HCA events does not appear to depend on the Bx component of the IMF. Considering the average radiance intensity across the dusk‐dawn meridian shows the HCA as a separate bulge inside the auroral oval and that the dawn side arc of the HCA is usually brighter than the dusk in the Lyman‐Birge‐Hopfield short band. We relate this to the expected field aligned current pattern of HCA formation. We further suggest that transpolar arcs observed in the dawn sector simultaneously in both northern and southern hemispheres are misidentified HCA.
InSight Pressure Data Recalibration, and Its Application to the Study of Long‐Term Pressure Changes on Mars
Authors: Lange L. , Forget F. , Banfield D. , Wolff M. , Spiga A. , Millour E. , Viúdez‐Moreiras D. , Bierjon A. , Piqueux S. , Newman C. , Pla‐García J. , Banerdt W. B. 
Published: May 2022

AbstractObservations of the South Polar Residual Cap suggest a possible erosion of the cap, leading to an increase of the global mass of the atmosphere. We test this assumption by making the first comparison between Viking 1 and InSight surface pressure data, which were recorded 40 years apart. Such a comparison also allows us to determine changes in the dynamics of the seasonal ice caps between these two periods. To do so, we first had to recalibrate the InSight pressure data because of their unexpected sensitivity to the sensor temperature. Then, we had to design a procedure to compare distant pressure measurements. We propose two surface pressure interpolation methods at the local and global scale to do the comparison. The comparison of Viking and InSight seasonal surface pressure variations does not show changes larger than ±8 Pa in the CO2 cycle. Such conclusions are supported by an analysis of Mars Science Laboratory (MSL) pressure data. Further comparisons with images of the south seasonal cap taken by the Viking 2 orbiter and MARCI camera do not display significant changes in the dynamics of this cap over a 40 year period. Only a possible larger extension of the North Cap after the global storm of MY 34 is observed, but the physical mechanisms behind this anomaly are not well determined. Finally, the first comparison of MSL and InSight pressure data suggests a pressure deficit at Gale crater during southern summer, possibly resulting from a large presence of dust suspended within the crater.