bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Associations Between Visitation, Social Media Use, and Search and Rescue in United States National Parks
Authors: Lu Zachary N. , Briggs Amy , Saadat Soheil , Algaze Isabel M. 
Published: October 2021

Introduction Search and rescue (SAR) is vital for visitor safety in US national parks, which are popular destinations for tourists. Previous studies have described SAR and seasonal visitation patterns, but not in the context of overall visitation. In addition, studies on the association between SAR and developed park areas remain limited. Concurrently, social media can be valuable for sharing information about conservation awareness and the joy of being outdoors. However, social media can potentially be an avenue for users to share risky and dangerous behaviors performed during attempts to obtain photos and videos. The associations between SAR and social media have not been discussed in existing literature. Methods Variables included recreational visits, developed site stay visits, backcountry visits, SAR incidents, and tweets. Data from 2017 were obtained from National Park Service visitor use statistics, the SAR incident dashboard, and the University of California, Irvine, Cloudberry application. Correlation analysis was performed using nonparametric Kendall rank correlation coefficients. Results Recreational visits were correlated with SAR incidents (rτ=0.415, P<0.001). Developed site stays were similarly correlated with SAR incidents (rτ=0.447, P<0.001), as were backcountry visits (rτ=0.428, P<0.001). Backcountry visits had a stronger correlation with fatalities (rτ=0.380, P<0.001) compared to developed site stays (rτ=0.304, P<0.001). Tweets were correlated with SAR incidents (rτ=0.468, P<0.001), recreational visits (rτ=0.403, P<0.001), and fatalities (rτ=0.367, P<0.001). Conclusions Our findings demonstrate associations between national park visitation, SAR incidents, fatalities, and Twitter use and provides a concept framework for future prospective studies to further investigate the relationships between visitation, SAR, and social media.
Imaging Elastodynamic and Hydraulic Properties of In Situ Fractured Rock: An Experimental Investigation Exploring Effects of Dynamic Stressing and Shearing
Authors: Wood Clay E. , Shokouhi Parisa , Manogharan Prabhakaran , Rivère Jacques , Elsworth Derek , Marone Chris 
Published: October 2021

AbstractWe describe laboratory experiments to elucidate the relationship between nonlinear elasticity and permeability evolution in fractured media subjected to local stress perturbations. This study is part of an effort to measure fluid pathways and fracture properties using active‐source acoustic monitoring during fluid injection and shear of rough fractures. Experiments were conducted with L‐shaped samples of Westerly granite fractured in situ under triaxial conditions with deionized water subsequently circulated through the resulting fractures. After in situ fracturing, we separately imposed oscillations of the applied normal stress and pore pressure with amplitudes ranging from 0.2 to 1 MPa and frequencies from 0.1 to 40 Hz. In response to normal stress and pore pressure oscillations, fractured Westerly granite samples exhibit characteristic transient softening, acoustic velocity fluctuations, and slow recovery, together with permeability enhancement or decay, informing us about the coupled nonlinear elastodynamic and poromechanical rock properties. Fracture interface properties (contact asperity stiffness, aperture) are then altered in situ by shearing, which generally decreases the measured elastic nonlinearity and permeability change for both normal stress and pore pressure oscillations.
Volume Budget of Subantarctic Mode Water in the Southern Ocean From an Ocean General Circulation Model
Authors: Jing Wandi , Luo Yiyong 
Published: October 2021

AbstractThe volume budget of Subantarctic Mode Water (SAMW) in the Southern Ocean (SO) is examined using a 0.1° ocean model output from 1950 to 2017. The results show that air–sea buoyancy fluxes, advective exports, and diapycnal mixing are all important to the SAMW volume budget. A climatological mean analysis finds that, for the SO as a whole, water in the SAMW density range ( kg m−3) is balanced between the following: formation due to air–sea buoyancy fluxes ( Sv), removal due to advective export northward out of the SO ( Sv), destruction due to diapycnal mixing ( Sv), and storage ( Sv). Decadal changes in the SAMW volume in the Indian and Pacific sectors display a two‐layer density structure, in which the volumes of the upper and lower layers vary predominantly out of phase with each other. In addition, the SAMW volume changes in the Indian and Pacific sectors appear to compensate each other on decadal time scales. The volume of SAMW in the SO has increased by ∼11% since the 1950s, and this increase tends to emerge gradually from denser to lighter layers. The increased SAMW volume mainly results from a consistent increase in oceanic buoyancy gain over the outcropping area at approximately 27.1 .
The Role of Intensifying Precipitation on Coastal River Flooding and Compound River‐Storm Surge Events, Northeast Gulf of Mexico
Authors: Dykstra S. L. , Dzwonkowski B. 
Published: October 2021

AbstractDestructive coastal floods are commonly increasing in frequency and may be caused by global precipitation intensification. Such connections through climate, watershed, and river processes are poorly understood because of complex interactions in transitional fluvial‐marine environments where flooding is caused by rivers, marine storm surge, or both in compound events. To better understand river floods along the fluvial‐marine transition, we study watersheds of the northeastern Gulf of Mexico using long‐term observations. Results show intensifying precipitation decreased precipitation‐discharge lag times, increasing river‐flood frequency and the likelihood of compound events in fluvial‐marine transitions. This reduction in lag time occurred when the Atlantic Multidecadal Oscillation and El Niño Southern Oscillation began strongly affecting river discharge through the advection of moist air, intensifying precipitation. Along the fluvial‐marine transition, compound events were largest in inland reaches. However, for inland reaches, compound event water levels did not exceed the floods caused solely by river flooding, the largest flood hazard in these systems. Our results demonstrate precipitation and river discharge play critical roles in coastal flooding and will likely escalate flooding as the climate continues to warm and intensify precipitation.
Seasonality and Life History Complexity Determine Vulnerability of Dungeness Crab to Multiple Climate Stressors
Authors: Berger Halle M. , Siedlecki Samantha A. , Matassa Catherine M. , Alin Simone R. , Kaplan Isaac C. , Hodgson Emma E. , Pilcher Darren J. , Norton Emily L. , Newton Jan A. 
Published: October 2021

AbstractScaling climate change impacts from individual responses to population‐level vulnerability is a pressing challenge for scientists and society. We assessed vulnerability of the most valuable fished species in the Northwest U.S.—Dungeness crab—to climate stressors using a novel combination of ocean, population, and larval transport models with stage‐specific consequences of ocean acidification, hypoxia, and warming. Integration across pelagic and benthic life stages revealed increased population‐level vulnerability to each stressor by 2100 under RCP 8.5. Under future conditions, chronic vulnerability to low pH emerged year‐round for all life stages, whereas vulnerability to low oxygen continued to be acute, developing seasonally and impacting adults, which are critical to population growth. Our results demonstrate how ontogenetic habitat shifts and seasonal ocean conditions interactively impact population‐level vulnerability. Because most valuable U.S. fisheries rely on species with complex life cycles in seasonal seas, chronic and acute perspectives are necessary to assess population‐level vulnerability to climate change.
Patched Local Lunar Gravity Solutions Using GRAIL Data
Authors: Goossens Sander , Fernández Mora Álvaro , Heijkoop Eduard , Sabaka Terence J. 
Published: October 2021

AbstractWe present a method to determine local gravity fields for the Moon using Gravity Recovery and Interior Laboratory (GRAIL) data. We express gravity as gridded gravity anomalies on a sphere, and we estimate adjustments to a background global start model expressed in spherical harmonics. We processed GRAIL Ka‐band range‐rate data with a short‐arc approach, using only data over the area of interest. We determine our gravity solutions using neighbor smoothing constraints. We divided the entire Moon into 12 regions and 2 polar caps, with a resolution of (which is equivalent to degree and order 1199 in spherical harmonics), and determined the optimal smoothing parameter for each area by comparing localized correlations between gravity and topography for each solution set. Our selected areas share nodes with surrounding areas and they are overlapping. To mitigate boundary effects, we patch the solutions together by symmetrically omitting the boundary parts of overlapping solutions. Our new solution has been iterated, and it has improved correlations with topography when compared to a fully iterated global model. Our method requires fewer resources, and can easily handle regionally varying resolution or constraints. The smooth model describes small‐scale features clearly, and can be used in local studies of the structure of the lunar crust.
Raman Spectral Shifts in Naturally Faulted Rocks
Authors: Muirhead D. K. , Kedar L. , Schito A. , Corrado S. , Bond C. E. , Romano C. 
Published: October 2021

AbstractRaman spectral shifts of carbonaceous materials arising from faulted rocks produce varied and complex results. By analyzing faulted and adjacent non‐faulted samples from three discrete localities in France, Italy, and Morocco, we assess changes in specific Raman parameters, including G‐peak width, G‐peak position, and peak intensity ratios. We consistently observe a shift in Raman parameters between faulted and non‐faulted samples; however, the direction and magnitude of this shift varies. Raman peak intensity ratios are shown to both increase and decrease on fault planes. The majority of samples exhibit decreasing peak width and peak position in the faulted samples, but this is not consistent; in two samples an increase is observed, but the shift tends to be small. These data are compared to published Raman spectral shifts from experimental fault data. Our results suggest that fault zone deformation processes may measurably change the carbon nanostructure in faulted rocks. The inconsistent nature of Raman spectral shifts in the fault rock samples analyzed, and those published suggest that a complex set of factors control carbon nanostructure changes in fault rocks. These factors, although not discriminated here, likely include, background temperature, frictional heating, strain, carbonaceous material type, amongst others. We have shown that Raman Spectral shifts occur in faulted rocks with implications for how Raman data are used to predict maximum temperatures in faulted sedimentary rocks. We recognize the potential for a range of fault zone processes to modify Raman spectral shifts, however, systematic sampling across individual fault zones is critical.
Variability in Timing and Transport of Pleistocene Meltwater Recharge to Regional Aquifers
Authors: Mowat Aidan C. , Francis Daniel J. , McIntosh Jennifer C. , Lindsay Matthew B. J. , Ferguson Grant A. G. 
Published: October 2021

AbstractThe impacts of Pleistocene glaciation on groundwater flow systems in sedimentary basins are widely recognized, but the timing and distribution of subglacial recharge events remain poorly constrained. We investigate the spatial and temporal variability of recharge events from glaciations over the last 2 million years in the Williston Basin, Canada. Integration of fluid chemistry, stable isotope data, and transport modeling indicate that meltwater arrived at depths of ∼600–1000 m in the northcentral region of the Williston Basin at two separate time periods, 75–150 and 300 ka, which we attribute to permeability differences between stacked aquifer systems. Our findings indicate that meltwater recharge extended along the northern margin of the Williston Basin as well as previously identified recharge areas to the east. Given the distance of measurements from recharge areas, evidence of recharge from the early to mid‐Pleistocene appears to be preserved in the Williston Basin.
Compound Parameterization to Improve the Accuracy of Radiation Emulator in a Numerical Weather Prediction Model
Authors: Song Hwan‐Jin , Roh Soonyoung , Park Hyesook 
Published: October 2021

AbstractTo improve the numerical weather prediction model over Korea using a neural network (NN) radiation emulator, two types of compound parameterization (CP) were developed. Although the CP returning to the original parameterization causes a considerable increase in the computational time, this increase can be compensated by the infrequent use of the radiation scheme, thus maintaining the 60‐fold speedup of the radiation process with the NN emulator. The first CP is based on the prediction of the heating rate error using the additional NN for all given input variables. In contrast, the second CP uses the cloud fraction to estimate the uncertainty of the NN emulator. As a result of model simulations for independent cases, including extreme flood events, the first CP was the most effective for passive use, whereas the second was useful in active use and exhibited the lowest error. Thus, these CP methods can help improve weather forecasting.
Ultra‐Thick Paleoregolith Layer Detected by Lunar Penetrating Radar: Implication for Fast Regolith Formation Between 3.6 and 2.35 Ga
Authors: Zhu Tieyuan , Zhang Jinhai , Lin Yangting 
Published: October 2021

AbstractLunar paleoregolith was formed by repeated asteroid impact and space weathering and then buried by later lava flows, serving as important records for early solar system history. However, direct observational evidence for the paleoregolith layer is rather limited. We present the evidence for the existence of the paleoregolith layer by processing 60 MHz lunar penetrating radar data acquired by the Chang’E‐3 Yutu rover. We find successive reflections with reversed polarities due to a low permittivity (paleoregolith) layer sandwiched in two high permittivity (lava) layers. From modeling and migration imaging of radar reflections, we determine an ultra‐thick paleoregolith layer (∼5–9 m) beneath the Eratosthenian unit and on the top of the Imbrian unit, suggesting a high regolith production rate of 5.8–10.5 m/Ga between late Imbrian and early Eratosthenian periods compared to the previous estimation ∼2 m/Ga, implying fast regolith formation and possible high meteoric flux during these periods.
A Tale of Two Radiation Belts: The Energy‐Dependence of Self‐Limiting Electron Space Radiation
Authors: Olifer L. , Mann I. R. , Kale A. , Mauk B. H. , Claudepierre S. G. , Baker D. N. , Spence H. E. , Ozeke L. G. 
Published: October 2021

AbstractThe flux of energetic electrons in the terrestrial Van Allen Belts varies by orders of magnitude during a magnetic storm. Here, we show how the dynamics of these electrons are clearly separated by energy into two distinct populations which are governed by different storm time behavior. We reveal how self‐limiting processes, described theoretically by Kennel and Petschek (1966), https://doi.org/10.1029/JZ071i001p00001, govern the energy‐dependent dynamics of the electrons. For terrestrial magnetic storms, accelerated electrons with energies below 850 keV quickly reach a maximum energy‐dependent differential flux level which is almost the same in every storm. Higher energy electrons typically do not reach a limiting flux and instead are governed by the differential impacts of competing acceleration and loss mechanisms. In general, electron fluxes saturate at the Kennel‐Petschek limit first at lower energies, impacting higher energies later in the storm. For the most intense storms, the maximum energy at which the fluxes are capped can also increase.
An Investigation of Auroral E Region Energy Exchange Using Poker Flat Incoherent Scatter Radar Observations During Fall Equinox Conditions
Authors: Zhan Weijia , Kaeppler Stephen R. , Larsen Miguel F. , Reimer Ashton , Varney Roger 
Published: October 2021

AbstractWe present new results using data collected by the Poker Flat Incoherent Scatter Radar (PFISR) of energy transfer rates, which include the effects from neutral winds in the high latitude E‐region ionosphere‐thermosphere (IT) during Fall 2015. The purpose of our investigation is to understand the magnetic local time (MLT) dependence of the peak energy transfer, which occurs asymmetrically in the morning‐evening (dawn‐dusk) MLT sector. The statistical characteristics of both altitude‐resolved and altitude‐integrated energy transfer rates in the auroral E region local to PFISR during different geomagnetic conditions are quantified. Our analysis shows that the geomagnetic activity level has large impacts on the energy transfer rates. In contrast with previous investigations, we find both the altitude integrated electromagnetic (EM) energy transfer rate and Joule heating rate are larger in the evening sector than in the morning sector during all geomagnetic activity conditions. We also observe a non‐negligible negative EM energy transfer rates below 110 km in the morning sector during active conditions, which is associated with neutral winds during this MLT interval. The statistical results show that the neutral winds tend to increase the Joule heating rate in a narrow altitude range in the morning sector and impact a broader region with respect to altitude and time in the evening sector in the E region under moderate and active conditions. We find that during quiet conditions that the neutral winds have a significant contribution to the Joule heating and contribute up to 75% of the Joule heating. However, during active conditions the enhanced electric fields are a dominant driver of Joule heating, while the neutral wind effects can reduce the Joule heating rates by 25% or more relative to the passive heating rates.
MAVEN Observations of Low Frequency Steepened Magnetosonic Waves and Associated Heating of the Martian Nightside Ionosphere
Authors: Fowler C. M. , Hanley K. G. , McFadden J. P. , Chaston C. C. , Bonnell J. W. , Halekas J. S. , Espley J. R. , DiBraccio G. A. , Schwartz S. J. , Mazelle C. , Mitchell D. L. , Xu S. , Lillis R. J. 
Published: October 2021

AbstractWe present Mars Atmosphere and Volatile EvolutioN (MAVEN) observations of low frequency steepened fast magnetosonic waves in the Martian magnetosphere and ionosphere. Solar wind pressure pulses generated in the upstream foreshock region impact the magnetopause and generate the magnetosonic waves within the magnetosphere, in a process analogous to the production of magnetic Pc pulsations in the terrestrial magnetosphere. The draped nature of the IMF about Mars, combined with the near‐perpendicular propagation of these waves across the magnetic field, act to channel these waves into the nightside ionosphere, where they are observed in their non‐linear steepened form. Coincident‐in‐time ion observations show that the light (H+) and heavy (O+, O2+, CO2+) planetary ion distribution functions possess significant suprathermal energetic tails, arising from wave‐particle interactions with the steepened waves. The short gyro period and small gyro radius of the protons, relative to the steepened waves, results in proton heating via adiabatic compression. In contrast, the long gyro period of the heavy ions relative to the wave frequency leads to nonadiabatic heating via wave‐trapping processes. The light and heavy ion species are heated above escape energy by these waves, even down close to the exobase. A limited statistical study of 101 neighboring orbits found that similar wave events occurred on 28% of orbits analyzed, suggesting that such wave‐heating events may be important drivers of the Mars nightside ionospheric dynamics and energy budget. Our discussion includes placing our results in the context of solar wind energy transfer to the ionospheres of unmagnetized and magnetized bodies in general.
Numerical Considerations in the Simulation of Equatorial Spread F
Authors: Li Zezhong , Lei Jiuhou , Zhang Binzheng 
Published: October 2021

AbstractThe ionospheric irregularities known as equatorial spread F (ESF) have drawn great attention in decades due to their disruption of communications and navigation systems. ESF is generally attributed to Rayleigh–Taylor instability, but there are still many remaining issues about its formation and evolution. Numerical simulations have been widely used to study such a phenomenon due to the complex nonlinear evolution of ESF. A two‐dimensional ESF model was developed in this work and a series of experiments were conducted to study the effects of grid resolution and numerical diffusion on idealized ESF simulation. It was found that advection schemes with the total variation diminishing property are preferred for preventing spurious oscillations which occur near the steep density gradients in the ESF. On the other hand, schemes with low diffusion are also desirable in order to model complicated dynamic structures of the ESF. Moreover, numerical experiments suggest that some of the secondary instabilities in idealized ESF simulations, although with morphological similarities, are possibly initiated by numerical seeding, which may differ from the observed evolution of secondary ESF.
Geodetic Constraints on a 25‐year Magmatic Inflation Episode Near Three Sisters, Central Oregon
Authors: Lisowski Michael , McCaffrey Robert , Wicks Charles W. , Dzurisin Daniel 
Published: October 2021

AbstractCrustal inflation near the Three Sisters volcanic center documented since the mid‐1990s has persisted for more than two decades. We update past analyses of the event through 2020 by simultaneously inverting InSAR interferograms, GPS time series, and leveling data for time‐dependent volcanic deformation source parameters. We explore several source models to estimate how the deformation rate varied through time and to identify parameters that can reproduce measured deformation. Our preferred model is a Mogi source 4.1 km below sea level (5.9 km below the surface) about 5 km west of the summit of South Sister. Inflation started in late 1995 or 1996; the rate increased rapidly during 1998–1999, and peaked in late 1999, resulting in maximum surface uplift of about 30 cm by mid‐2020. Since 2000, the inflation rate generally declined exponentially with a time constant of about 6 years. Two source inflation scenarios fit the data equally well. In the first, the crust surrounding the source is elastic and the net source‐volume increase, which we attribute to persistent magma input, has been about 49 × 106 m3. The second scenario adds a viscoelastic shell surrounding the Mogi source. In that case, an injection of about 21 × 106 m3 of magma prior to 2000, followed by continuing relaxation of the viscoelastic shell, can account for most of the observed surface deformation. In both scenarios, modeling reveals quasiperiodic increases in the inflation rate (pulses) with a recurrence interval of 3–4 years, both before and after 2000.