bluuebunny/crossref_metadata_2025 huggingface dataset:
Atmospheric Nitrous Oxide Variations on Centennial Time Scales During the Past Two Millennia
Authors: Ryu Y. , Ahn J. , Yang J.‐W. , Brook E. J. , Timmermann A. , Blunier T. , Hur S. , Kim S.‐J.
Published: August 2020

The continuous growth of atmospheric nitrous oxide (N2O) is of concern for its potential role in global warming and future stratospheric ozone destruction. Climate feedbacks that enhance N2O emissions in response to global warming are not well understood, and past records of N2O from ice cores are not sufficiently well resolved to examine the underlying climate‐N2O feedbacks on societally relevant time scales. Here, we present a new high‐resolution and high‐precision N2O reconstruction obtained from the Greenland NEEM (North Greenland Eemian Ice Drilling) and the Antarctic Styx Glacier ice cores. Covering the N2O history of the past two millennia, our reconstruction shows a centennial‐scale variability of ~10 ppb. A pronounced minimum at ~600 CE coincides with the reorganizations of tropical hydroclimate and ocean productivity changes. Comparisons with proxy records suggest association of centennial‐ to millennial‐scale variations in N2O with changes in tropical and subtropical land hydrology and marine productivity.
Laboratory Electrical Conductivity of Marine Gas Hydrate
Authors: Constable Steven , Lu Ryan , Stern Laura A. , Du Frane Wyatt L. , Roberts Jeffery J.
Published: August 2020

Methane hydrate was synthesized from pure water ice and flash frozen seawater, with varying amounts of sand or silt added. Electrical conductivity was determined by impedance spectroscopy, using equivalent circuit modeling to separate the effects of electrodes and to gain insight into conduction mechanisms. Silt and sand increase the conductivity of pure hydrate; we infer by contaminant NaCl contributing to conduction in hydrate, to values in agreement with resistivities observed in well logs through hydrate‐saturated sediment. The addition of silt and sand lowers the conductivity of hydrate synthesized from seawater by an amount consistent with Archie's law. All samples were characterized using cryogenic scanning electron microscopy and energy dispersive spectroscopy, which show good connectivity of salt and brine phases. Electrical conductivity measurements of pure hydrate and hydrate mixed with silt during pressure‐induced dissociation support previous conclusions that sediment increases dissociation rate.
Massive Ice Control on Permafrost Coast Erosion and Sensitivity
Authors: Lim M. , Whalen D. , Martin J. , Mann P. J. , Hayes S. , Fraser P. , Berry H. B. , Ouellette D.
Published: August 2020

High overall rates of permafrost cliff retreat, coupled with spatial variability, have been accompanied by increased uncertainty over future landscape dynamics. We map long‐term (>80 years) retreat of the shoreline and photogrammetrically analyze historic aerial imagery to quantify the processes at a permafrost coast site with massive ground ice. Retreat rates have been relatively constant, but topographic changes show that subsidence is a potentially critical but often ignored component of coastal sensitivity, exceeding landward recession by over three times during the last 24 years. We calibrate novel passive seismic surveys along clear and variable exposures of massive ground ice and then spatially map key subsurface layers. Combining decadal patterns of volumetric change with new ground ice variation maps enables past trends to be interpreted, future volumetric geomorphic behavior to be better constrained, and improves the assessment of permafrost coast sensitivity and the release of carbon‐bearing material.
To What Extent Biomass Burning Aerosols Impact South America Seasonal Climate Predictions?
Authors: Freire Julliana L. M. , Longo Karla M. , Freitas Saulo R. , Coelho Caio A. S. , Molod Andrea M. , Marshak Jelena , da Silva Arlindo , Ribeiro Bruno Z.
Published: August 2020

We applied the Goddard Earth Observing System for subseasonal to seasonal climate prediction to assess the impact of inclusion biomass burning (BB) aerosols over South America (SA) during the austral winter. We also evaluated the model sensitivity to the BB emissions prescription using no emissions, monthly climatological, and daily emissions. Each hindcast consisted of four members running from June to November of each year between 2000 and 2015. Our results indicated that interactive BB aerosols improve the seasonal climate prediction performance over SA. More realistic daily based emissions significantly further improve the performance in comparison with the climatological ones. Therefore, improvements in the BB emissions representation are urged to represent the aerosol impacts on seasonal climate prediction performance adequately.
Surface Melting Drives Fluctuations in Airborne Radar Penetration in West Central Greenland
Authors: Otosaka Inès N. , Shepherd Andrew , Casal Tânia G. D. , Coccia Alex , Davidson Malcolm , Di Bella Alessandro , Fettweis Xavier , Forsberg René , Helm Veit , Hogg Anna E. , Hvidegaard Sine M. , Lemos Adriano , Macedo Karlus , Kuipers Munneke Peter , Parrinello Tommaso , Simonsen Sebastian B. , Skourup Henriette , Sørensen Louise Sandberg
Published: August 2020

Greenland Ice Sheet surface melting has increased since the 1990s, affecting the rheology and scattering properties of the near‐surface firn. We combine firn cores and modeled firn densities with 7 years of CryoVEx airborne Ku‐band (13.5 GHz) radar profiles to quantify the impact of melting on microwave radar penetration in West Central Greenland. Although annual layers are present in the Ku‐band radar profiles to depths up to 15 m below the ice sheet surface, fluctuations in summer melting strongly affect the degree of radar penetration. The extreme melting in 2012, for example, caused an abrupt 6.2 ± 2.4 m decrease in Ku‐band radar penetration. Nevertheless, retracking the radar echoes mitigates this effect, producing surface heights that agree to within 13.9 cm of coincident airborne laser measurements. We also examine 2 years of Ka‐band (34.5 GHz) airborne radar data and show that the degree of penetration is half that of coincident Ku‐band.
Evidence of Nonlinear Interactions Between Magnetospheric Electron Cyclotron Harmonic Waves
Authors: Gao Zhonglei , Zuo Pingbing , Feng Xueshang , Wang Yi , Jiang Chaowei , Wei Fengsi
Published: August 2020

Electron cyclotron harmonic (ECH) waves play an important role in the magnetosphere‐ionosphere coupling. They are usually considered to be generated by the Bernstein‐mode instability with electron loss cone distributions. By analyzing the Van Allen Probes wave data, we present the direct evidence of the nonlinear interactions between ECH waves in the magnetosphere. Substorm‐injected electrons excite primary ECH waves in a series of structureless bands between multiples of the electron gyrofrequency. Nonlinear interactions between the primary ECH waves produce secondary waves at sum‐ and difference‐frequencies of the primary waves. Our results suggest that the nonlinear wave‐wave interactions can redistribute the primary ECH wave energy over a broader frequency range and hence potentially affect the magnetospheric electrons over a broader range of pitch angles and energies.
High‐Resolution Evidence for Middle Holocene East Asian Winter and Summer Monsoon Variations: Snapshots of Fossil Coral Records
Authors: Asami Ryuji , Yoshimura Natsumi , Toriyabe Hiroto , Minei Shogo , Shinjo Ryuichi , Hongo Chuki , Sakamaki Takashi , Fujita Kazuhiko
Published: August 2020

We first generated 53‐, 4‐, 10‐, and 9‐year‐long bimonthly time series of oxygen isotopes (δ18O), Sr/Ca, and U/Ca from 4.4 and 4.9 ka corals in Okinawa, Japan. Results indicate that the mid‐Holocene sea surface temperature (SST) and seawater δ18O were <1°C lower and 0.1–0.2‰ higher than today. Spectral analyses of reconstructed SST and seawater δ18O time series revealed East Asia monsoon (EAM) and El Niño/Southern Oscillation (ENSO) variations. Moreover, the latter had a dominant component of decade‐scale hydrologic variations. The Sr/Ca and U/Ca variations with removal of the ENSO component showed larger fluctuations by ~2°C in winter and ~0.6°C in summer at 4.4 ka relative to today, demonstrating (slightly) greater influences of the EAM variation on the northwestern subtropical Pacific in winter (summer) at that time, which are probably caused by enhancement of the EAM intensity and/or a southward migration of the latitudinal circulation.
Observed Hemispheric Asymmetry in Stratospheric Transport Trends From 1994 to 2018
Authors: Strahan Susan E. , Smale Dan , Douglass Anne R. , Blumenstock Thomas , Hannigan James W. , Hase Frank , Jones Nicholas B. , Mahieu Emmanuel , Notholt Justus , Oman Luke D. , Ortega Ivan , Palm Mathias , Prignon Maxime , Robinson John , Schneider Matthias , Sussmann Ralf , Velazco Voltaire A.
Published: August 2020

Total columns of the trace gases nitric acid (HNO3) and hydrogen chloride (HCl) are sensitive to variations in the lower stratospheric age of air, a quantity that describes transport time scales in the stratosphere. Analyses of HNO3 and HCl columns from the Network for the Detection of Atmospheric Composition Change panning 77°S to 79°N have detected changes in the extratropical stratospheric transport circulation from 1994 to 2018. The HNO3 and HCl analyses combined with the age of air from a simulation using the MERRA2 reanalysis show that the Southern Hemisphere lower stratosphere has become 1 month/decade younger relative to the Northern Hemisphere, largely driven by the Southern Hemisphere transport circulation. The analyses reveal multiyear anomalies with a 5‐ to 7‐year period driven by interactions between the circulation and the quasi‐biennial oscillation in tropical winds. This hitherto unrecognized variability is large relative to hemispheric transport trends and may bias ozone trend regressions.
Global Marine Isochore Estimates Using Machine Learning
Authors: Lee Taylor R. , Phrampus Benjamin J. , Obelcz Jeffrey , Wood Warren T. , Skarke Adam
Published: August 2020

The thickness normal to deposition (isopachs) and vertical thickness (isochores) of geological units is important for assessing various geologic processes. We present the first marine global sediment isochore estimates for five geological periods dating from middle Miocene (15.97 Ma) to present. We use sparsely distributed sediment depth vs. age observations from the Deep Sea Drilling Project and global maps of biological, oceanographic, geographic, and geological variables as training features in a k‐nearest neighbor regressor to estimate isochores. Results are compared to isochore estimates generated by applying a constant depositional rate from recent estimates of global total sediment thicknesses. Both models of isochore thickness exhibit consistent error. Results from a machine learning approach show major advantages, including results that are quantitative, easily updatable, and accompanied with uncertainty estimation. Final predictions can provide first‐order constraints on sediment deposition with geologic time, which is of timely importance for assessing past climate variability.
Using Seismic Noise Levels to Monitor Social Isolation: An Example From Rio de Janeiro, Brazil
Authors: Dias Fábio L. , Assumpção Marcelo , Peixoto Pedro S. , Bianchi Marcelo B. , Collaço Bruno , Calhau Jackson
Published: August 2020

Decrease of seismic noise level, after reduction of traffic due to the COVID‐19 pandemic, has been observed worldwide. The possibility of using seismic noise as another proxy to estimate social isolation was tested with a station within Rio de Janeiro city. We used the isolation index measured from smartphone movement to calibrate the seismic noise levels and estimated an Isolation Seismic Index, ISI (% of the population at home), using the seismic noise energy. Noise levels best correlate with isolation measures in the frequency range 4–8 Hz. Small differences between the smartphone and the ISI indexes are interpreted as differences in social activities and noise sources. All mobility indexes are proxies to the actual isolation. Although ISI does not measure the number of people outside, it measures the number of noise sources (vehicles, trains, factories, etc.) and can be used as additional information to interpret anomalies in other proxies.
Step Increase in Eastern U.S. Precipitation Linked to Indian Ocean Warming
Authors: Strong Courtenay , McCabe Gregory J. , Weech Alexander
Published: August 2020

A step increase in annual precipitation over the eastern United States in the early 1970s commenced five decades of invigorated hydroclimate, with ongoing impacts on streamflow and water resources. Despite its far‐reaching impacts, the dynamical origin of this change is unknown. Here analyses of a century of atmospheric and oceanic data trace the dynamics to changes in the Indian Ocean. Increases in fall precipitation contribute most strongly to the step increase, and the associated mechanism is emergence of a pan‐Pacific atmospheric wave emanating from deep convection over the warming Indian Ocean. Documentation of this fall teleconnection draws attention to projected anthropogenic increases in tropical oceanic heat content and their potential impacts on hydroclimate of the midlatitudes.
Dayside Auroral Observation Resulting From a Rapid Localized Compression of the Earth's Magnetic Field
Authors: Briggs Jennifer K. , Fasel Gerard J. , Silveira Marcos , Sibeck David G. , Lin Yu , Sigernes Fred
Published: August 2020

This paper presents observations of dayside auroral signatures resulting from a massive localized compression of the magnetopause, magnetosheath, and bow shock. On 10 December 2016, the Magnetospheric Multiscale Mission (MMS) spacecraft observed a compression of the entire magnetosheath and bow shock, which moved past the spacecraft in 1 min and 45 s. Shortly afterward, the resulting auroral signature was observed at the Kjell Henriksen Observatory located in Longyearbyen, Norway. The characteristics of this unique event have major ramifications for understanding dayside magnetospheric physics.
First Measurements of Low‐Frequency Sferics Associated With Terrestrial Gamma‐Ray Flashes Produced by Equatorial Thunderstorms
Authors: Zhang Hongbo , Lu Gaopeng , Lyu Fanchao , Ahmad Mohd Riduan , Qie Xiushu , Cummer Steven A. , Xiong Shaolin , Briggs Michael S.
Published: August 2020

The low‐frequency (LF) lightning sferics associated with terrestrial gamma‐ray flashes (TGFs) detected by Fermi Gamma‐ray Burst Monitor over equatorial thunderstorms have been recorded at a station in Melaka, Malaysia, since 2017. We examine the LF sferics of two Fermi TGFs, including one TGF‐associated lightning discharge at only about 28 km range. Both TGFs are related to the strongest pulse during the initial stage of their parent intracloud (IC) lightning, while in both cases, the light curve of gamma‐ray photon lags the major lightning pulse by approximately 100 μs. TGF occurred about 3 ms after the lightning initiation when the initial upward negative leader has ascended for about 2 km to reach the height of 10–11 km. Our analyses on a statistical basis show that TGF‐related lightning is mostly located in the strong convection of equatorial thunderstorms at the mature stage, and nearly half TGFs are not produced in the strongest convection region.
Intermittent Slip Along the Alto Tiberina Low‐Angle Normal Fault in Central Italy
Authors: Vuan A. , Brondi P. , Sugan M. , Chiaraluce L. , Di Stefano R. , Michele M.
Published: August 2020

The Alto Tiberina normal fault (ATF) in central Italy is a 50‐km‐long crustal structure that dips at a low angle (15–20°). Events on the fault plane are about 10 times less frequent than those located in its shallower syn‐ and antithetic hanging‐wall splays. To enhance ATF catalog and achieve a better understanding of the degree of coupling in the fault system, we apply a template matching technique in the 2010–2014 time window. We augment by a factor 5 the detections and decrease the completeness magnitude to negative values. Contrary to what previously observed on ATF, we highlight intermittent seismic activity and long‐lasting clusters interacting with sequences on the shallower splays. One of these episodes of prolonged seismic activity, detected at the end of 2013 on a 30‐km‐long ATF segment, suggest the ATF active role during an aseismic transient unraveled by geodetic data.
Evidence of Hydrological Intensification and Regime Change From Northern Alaskan Watershed Runoff
Authors: Arp C. D. , Whitman M. S. , Kemnitz R. , Stuefer S. L.
Published: August 2020

Snowmelt‐dominated runoff regimes have defined northern Alaskan rivers. Discharge records from three watersheds within the National Petroleum Reserve in Alaska (NPR‐A) span 19 years and capture three notable periods of changing runoff. In the first, 2001–2008, mean annual runoff (MAR) averaged 90 mm, characterized by sharp snowmelt runoff and summer drought. Over the next 7 years, larger MAR averaged 120 mm driven by high and early snowmelt runoff. The most recent 4 years, 2016–2019, had even higher MAR of 163 mm with high and sustained late summer flows. Hydrograph analysis suggests a shift toward rainfall‐dominated runoff in the most recent period compared to snowmelt‐dominated hydrographs in the previous two. Declining sea ice appears closely linked to increasing late summer precipitation and a shift toward rainfall runoff. Future development in the NPR‐A will require continued hydrological monitoring and planning to mitigate flood and erosion hazards, permafrost degradation, and ecosystem impairment.
Momentum and Energy Predict the Backwater Rise Generated by a Large Wood Jam
Authors: Follett E. , Schalko I. , Nepf H.
Published: August 2020

Wood reintroduction is now considered an important aspect of stream restoration, due to ecohydraulic benefits associated with wood presence. Channel‐spanning wood jams create an upstream backwater, increasing flow heterogeneity, sediment deposition, and ecological productivity, but also flood risk. Backwater rise prediction is necessary to evaluate flood hazards in hydraulic models, improve design of engineered logjam projects, and compare jam effects across river systems. We present experimental results demonstrating that a jam can be modeled as a porous obstruction generating momentum loss proportional to the number, size, and packing density of the logs and the jam length. Energy and momentumconstraints are combined to predict backwater rise from unit discharge and a dimensionless structural parameter. This novel approach allows description of preexisting jams with a common metric. The model was used to demonstrate how backwater length, pool size, and upstream sediment deposition depend on jam structure and channel slope.
Reduced Poleward Transport Due to Stratospheric Heating Under Stratospheric Aerosols Geoengineering
Authors: Visioni Daniele , MacMartin Douglas G. , Kravitz Ben , Lee Walker , Simpson Isla R. , Richter Jadwiga H.
Published: August 2020

By injecting SO2 into the stratosphere at four latitudes (30°, 15°N/S), it might be possible not only to reduce global mean surface temperature but also to minimize changes in the equator‐to‐pole and inter‐hemispheric gradients of temperature, further reducing some of the impacts arising from climate change relative to equatorial injection. This can happen only if the aerosols are transported to higher latitudes by the stratospheric circulation, ensuring that a greater part of the solar radiation is reflected back to space at higher latitudes, compensating for the reduced sunlight. However, the stratospheric heating produced by these aerosols modifies the circulation and strengthens the stratospheric polar vortex which acts as a barrier to the transport of air toward the poles. We show how the heating results in a feedback where increasing injection rates lead to stronger high‐latitudinal transport barriers. This implies a potential limitation in the high‐latitude aerosol burden and subsequent cooling.
In Situ Observation of the Phase Transition Behavior of Shocked Baddeleyite
Authors: Takagi Sota , Kyono Atsushi , Nozawa Shunsuke , Kawai Nobuaki , Inukai Koji , Fukaya Ryo , Funamori Nobumasa , Adachi Shin‐ichi , Ichiyanagi Kouhei
Published: August 2020

Baddeleyite (ZrO2) is used to infer shock pressures and understand the impact history of planetary bodies. Although the high‐pressure phase transition behavior of baddeleyite has been intensively investigated under hydrostatic conditions, there is little information on the dynamic response of phase transitions under shock‐loading conditions. We performed in situ X‐ray diffraction measurements on shock‐loaded baddeleyite using a synchrotron X‐ray pulse at beamline NW14A of the Photon Factory Advanced Ring, High Energy Accelerator Research Organization (KEK), Japan. A phase transition from monoclinic to orthorhombic‐I ZrO2 occurs at 3.3 GPa during shock compression and immediately returns to the monoclinic phase during subsequent release. Orthorhombic‐II ZrO2 is not observed up to 15 GPa. This study refines the phase transition behavior of baddeleyite under shock conditions up to 15 GPa, and the phase transition boundary is determined from direct observations. These findings improve the understanding of the shock history of planetary bodies.
Crater Morphometry on the Mafic Floor Unit at Jezero Crater, Mars: Comparisons to a Known Basaltic Lava Plain at the InSight Landing Site
Authors: Warner Nicholas H. , Schuyler Andrew J. , Rogers A. Deanne , Golombek Matthew P. , Grant John , Wilson Sharon , Weitz Cathy , Williams Nathan , Calef Fred
Published: August 2020

A secondary objective for the Perseverance rover mission to Jezero crater, Mars, is to collect igneous rocks for analysis on Earth. The mafic crater floor unit (MFU) represents the best candidate. Ten‐meter‐scale craters on the MFU exhibit rocky ejecta, rims, and slopes that indicate resistant rock. The frequency distribution of these craters is, however, low. Comparisons of MFU craters to craters on a lava plain at the Interior Exploration using Seismic Investigation, Geodesy and Heat Transport mission (InSight) landing site reveal that the MFU lacks a granular regolith. Removal of regolith or exhumation of the MFU explains the rocky crater morphology and low density. Erosion rates, calculated using crater retention timescales of ~2.0 Ga for both locations, are 10−3 to 10−4 m/Myr. The rates derive from craters impacted into rocky materials on the MFU versus regolith at InSight. The difference in material strength, yet comparable erosion rates, requires more vigorous surface processes at Jezero relative to global averages on Mars.
Ocean Heat Storage Rate Unaffected by MOC Weakening in an Idealized Climate Model
Authors: Shatwell Peter , Czaja Arnaud , Ferreira David
Published: August 2020

To study the role of the Atlantic meridional overturning circulation (AMOC) in transient climate change, we perform an abrupt CO2‐doubling experiment using a coupled atmosphere‐ocean‐ice model with a simple geometry that separates the ocean into small and large basins. The small basin exhibits an overturning circulation akin to the AMOC. Over the simulated 200 years of change, it stores heat at a faster rate than the large basin by 0.6 ± 0.2 W m−2. We argue that this is due to the small basin MOC. However, we find that as the MOC weakens significantly, it has little impact on the small basin's heat storage rate. We suggest this is due to the effects of both compensating warming patterns and interbasin heat transports. Thus, although the presence of a MOC is important for enhanced heat storage, MOC weakening is surprisingly unimportant.
Generalized Substorm Current Wedge Model: Two Types of Dipolarizations in the Inner Magnetosphere
Authors: Ohtani S. , Motoba T. , Takahashi K. , Califf S.
Published: August 2020

The present study investigates dipolarization signatures in the inner magnetosphere using sharp geosynchronous dipolarizations as a reference. The results are summarized as follows: (1) The region of sharp and structured dipolarizations expands earthward while dipolarizations are sustained at geosynchronous orbit; (2) within 5 RE from Earth, dipolarization signatures are often smooth and gradual, resembling midlatitude positive bays, and they start simultaneously with substorm onsets; (3) off the equator (>0.5 RE), sharp dipolarizations often take place before geosynchronous dipolarizations. These results can be explained by a model current system with R1‐sense and R2‐sense current wedges (R1CW and R2CW) if (a) the R1CW, which is located outside, is more intense than the R2CW in total current, (b) the R1CW stays outside of geosynchronous orbit, and (c) the R2CW moves earthward. The model suggests that the region of sharp dipolarizations is confined between the two current wedges, and it expands earthward as the R2CW moves earthward (Result 1). Sufficiently earthward of the R2CW, the remote effect of the R1CW dominates that of the R2CW, and accordingly, magnetic disturbances resemble midlatitude positive bays (Result 2). Since the timing of sharp dipolarizations is determined by the passage of the R2CW, they take place earlier for outer flux tubes. Away from the magnetic equator, sharp dipolarizations can precede geosynchronous dipolarizations especially if the magnetic configuration is stretched (Result 3). Thus, this double‐current wedge model explains the variability of dipolarization signatures at different distances, and it may be regarded as a generalized substorm current wedge model.
Explicit Global Simulation of Gravity Waves in the Thermosphere
Authors: Becker Erich , Vadas Sharon L.
Published: August 2020

We present a new version of the high‐resolution Kühlungsborn Mechanistic general Circulation Model (KMCM) extended to z ∼ 450 km. This model is called HIAMCM (HI Altitude Mechanistic general Circulation Model) and explicitly simulates gravity waves (GWs) down to horizontal wavelengths of λh ∼ 165 km. We find predominant tertiary GWs in the winter thermosphere at middle/high latitudes. These GWs typically have horizontal wavelengths λh ∼ 300–1,100 km, ground‐based periods ∼ 25–90 min, and intrinsic horizontal phase speeds cIh ∼ 250–350 m s−1. Above z ∼ 200 km, the predominant GW horizontal propagation directions are roughly against the background winds from the diurnal tide; the GWs propagate mainly poleward at midnight, eastward at 6 local time (LT), equatorward at noon, and westward at 18 LT. Wintertime GWs at z ∼ 300 km having 165 km ≤ λh ≤ 330 km create a large hot spot over the Southern Andes/Antarctic Peninsula that agrees well with quiet time satellite measurements. Due to cancelation effects, the time‐averaged zonal mean Eliassen‐Palm flux divergence from the resolved GWs in the thermosphere is negligible compared to that of the tides and compared to the zonal component of the time‐averaged zonal mean ion drag. We also find that the thermospheric GWs dissipate mainly from macroturbulent diffusion and, above z ∼ 200 km, from molecular diffusion, whereas the tides dissipate mainly from ion drag. The averaged dissipative heating in the thermosphere due to tides is much stronger than that due to GWs.
Generation and Evolution of Two Opposite Types of Mesoscale Plasma Sheet Bubbles
Authors: Wang Chih‐Ping , Yang Jian , Gkioulidou Matina , Lyons Larry R. , Wolf Richard A.
Published: August 2020

Previous observations showed that there are two major types of mesoscale plasma sheet bubbles (plasma with relatively lower total entropy than ambient plasma): the type‐1 has density lower and temperature higher than ambient plasma, and the type‐2 has the opposite differences. We first show, from statistical analysis of observations, that both the type‐1 and type‐2 bubbles can be possibly generated locally by magnetic reconnection in the magnetotail. We then conduct simulations based on the Rice Convection Model to show that the density and temperature characteristics of a bubble can affect the bubble's evolution and associated magnetic field and flow perturbations through magnetic drift and precipitation. For both types, the bubble extends azimuthally as it moves inward, and Bz is enhanced near the bubble's earthward front. The flow perturbations within the bubble consist of two interchange flow vortices with a fast earthward‐flow channel near the center and return flows on the two sides. The low entropy of a bubble is contributed by the reduction in the higher energy ions in the type‐2 bubble but in the lower energy ions in the type‐1 bubble. Duskward magnetic drift of the bubble's depleted high‐energy ions allows the type‐2 bubble and the Bz enhancement to expand azimuthally wider toward dusk than does the type‐1 bubble. The electrons within the type‐2 bubble produce weaker ionospheric conductance, in particular on the dawnside of the bubble because these electrons drift toward dawn, which results in stronger flows within the dawnside flow vortex, as compared to the type‐1 bubble.
A Comparative Study of Spacecraft Charging Onset at Geosynchronous Altitudes: A Nonextensive Particle Approach
Authors: Ali S. , Rubab N. , Nawaz K. , Sarwar S.
Published: August 2020

Space plasma particlesand space weather conditions strongly affect spacecraft and satellites at geosynchronous Earth orbit (GEO) and their charging essentially occurs for incoming primary electrons and outgoing secondary and backscattered electrons. Due to the presence of high energetic (superthermal) electrons at GEO altitudes, a generalized power law q‐nonextensive particle distribution is utilized to solve the current‐balance equation for spacecraft charging both analytically and numerically. The impact of subextensivity (q>1) and superextensivity (q<1) is discussed for plasma systems to analyze more pronounced energy tails associated with q distribution as compared to standard Kappa distribution. The present findings indicate the suitability of proposed distribution for better describing the charge triggering as compared to Kappa and Maxwellian distributions. Furthermore, numerical estimation is made for identifying the current and charging onset due to various space grade materials.
Nondetection of Radio Emissions From Titan Lightning by Cassini RPWS
Authors: Fischer G. , Farrell W. M. , Gurnett D. A. , Kurth W. S.
Published: August 2020

The Saturn‐orbiting Cassini spacecraft completed 126 close Titan flybys from 2004 until 2017. During almost all of them the Cassini Radio and Plasma Wave Science (RPWS) instrument was turned on to search for radio emissions attributed to Titan lightning. Here we report about their nondetection after close inspection of all Titan flybys throughout the Cassini mission. We also infer new and strong constraints on the permissible flash energy and flash rate of potential Titan lightning. The nondetection of lightning flashes by Cassini observations implies that any lightning on Titan must be either very weak, very rare, or does not exist at all, and the latter could be due to cloud electric fields being too low to initiate a discharge. This finding holds important implications for the prebiotic chemistry of Titan and also implies that lightning will not be a significant hazard to the upcoming Dragonfly mission.
Thank You to Our 2019 Reviewers
Authors: East Amy E. , Finnegan Noah Joseph , Hoitink A. J. F. (Ton) , Sergienko Olga V.
Published: August 2020

During 2019, the Journal of Geophysical Research‐Earth Surface handled a record‐high number of submitted manuscripts. Managing these in order to deliver the highest‐quality published science relies, of course, on obtaining quality peer review. We all recognize the demand that this places on the reviewers' time, especially as members of the Earth surface scientific community receive ever increasing numbers of requests to review manuscripts for many journals. The editors wish to extend our sincere thanks to all the 674 reviewers who volunteered their time to provide 962 reviews for JGR‐Earth Surface in 2019. We certainly appreciate the time and effort that these reviewers have put into writing insightful, constructive review comments, an essential part of moving the science forward.
ELABELA attenuates deoxycorticosterone acetate/salt-induced hypertension and renal injury by inhibition of NADPH oxidase/ROS/NLRP3 inflammasome pathway
Authors: Chen Zhida , Wu Chunying , Liu Yuting , Li Haonan , Zhu Yeyan , Huang Cailing , Lin Huangbo , Qiao Qiao , Huang Mengming , Zhu Qing , Wang Lei
Published: August 2020

ELABELA (ELA), a 32-residue hormone peptide abundantly expressed in adult kidneys, has been identified as a novel endogenous ligand for APJ/Apelin receptor. The aim of this study was to investigate the role of ELA in deoxycorticosterone acetate (DOCA)/salt-induced hypertension and further explore the underlying mechanism. In DOCA/salt-treated rats, the mRNA level of ELA greatly decreased in the renal medulla. Next, overexpression of ELA in the kidney was found to attenuate DOCA/salt-induced hypertension and renal injury, including lower blood pressure, reversed glomerular morphological damage, decreased blood urea nitrogen (BUN), and blocked the accumulation of fibrotic markers. Mechanistically, ELA overexpression inhibited renal nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity and subsequent reactive oxygen species (ROS) production, thus resulted in the blockade of formation and activation of Nod-like receptor protein 3 (NLRP3) inflammasome. The inhibitory effects of ELA on Aldosterone-stimulated NADPH oxidase/ROS/NLRP3 inflammasome pathway were confirmed in the human renal tubular cells. Furthermore, our in vivo and in vitro results showed that the deficiency of the apelin receptor APJ did not influence the antihypertensive effect and blockage to NADPH oxidase/ROS/NLRP3 pathway of ELA. Moreover, in heterozygous ELA knockout mice (ELA+/−), the ELA deficiency remarkably accelerated the onset of DOCA/salt-induced hypertension. Our data demonstrate that ELA prevents DOCA/salt-induced hypertension by inhibiting NADPH oxidase/ROS/NLRP3 pathway in the kidney, which is APJ independent. Pharmacological targeting of ELA may serve as a novel therapeutic strategy for the treatment of hypertensive kidney disease.
Prognostic significance of Rab27 expression in solid cancer: a systematic review and meta-analysis
Authors: Koh Hyun Min , Jang Bo Gun , Kim Dong Chul
Published: August 2020

Rab27 is an essential molecule of vesicle fusion and trafficking in exosome secretion process, which plays important roles in cancer progression and metastasis. Recent studies reported that Rab27 expression is also associated with cancer prognosis. Therefore, we performed a meta-analysis to reveal the prognostic significance of Rab27 expression in solid cancer. Data were extracted by searching on PubMed, Embase and Cochrane library until February 15 2020. Pooled hazard ratio (HR) with confidence interval (CI) was calculated to evaluate the association between Rab27 expression and survival in solid cancer. Ten studies with 1434 cancer patients were including for this meta-analysis. High expression of Rab27 was associated with poor survival (HR 2.67, 95% CI 1.52–4.69, p = 0.001). High expression of Rab27A was significantly associated with lymph node metastasis (HR 1.53, 95% CI 1.00–2.34, p = 0.048). High expression of Rab27B was significantly correlated with lymph node and distant metastasis (HR 2.15, 95% CI 1.56–2.95, p < 0.001; HR 6.80, 95% CI 3.12–14.85, p < 0.001), and higher TNM stage (HR 2.55, 95% CI 1.78–3.65, p < 0.001). This meta-analysis revealed that Rab27 expression could be a potential prognostic marker in solid cancer.
A heterogeneous bio-inspired peroxide shunt for catalytic oxidation of organic molecules
Authors: Mukherjee Manjistha , Dey Abhishek
Published: August 2020

Iron porphyrins with three different axial ligands installed atop self-assembled monolayer modified gold electrodes can oxidize C–H bonds and epoxidize alkenes efficiently using H2O2via the formation of a high-valent intermediate.
Mitochondria-targeted polydopamine nanoprobes for visualizing endogenous sulfur dioxide derivatives in a rat epilepsy model
Authors: Ci Qiaoqiao , Qin Xiaofei , Liu Jinhua , Wang Rui , Li Zheng , Qin Wenjing , Lim Kah-Leong , Zhang Cheng-Wu , Li Lin
Published: August 2020

The authors designed and synthesized a mitochondria-targeted polydopamine nanoprobe for visualizing endogenous SO32−/HSO3− by the nucleophilic addition reaction. The nanoprobe was used for imaging SO2 derivatives both in the mitochondria of cells, zebrafish, and hippocampus of a rat model of epilepsy.
Practical and inexpensive acid-activated montmorillonite catalysts for energy-efficient CO2 capture
Authors: Bhatti Umair H. , Kazmi Wajahat W. , Muhammad Hafiz A. , Min Gwan Hong , Nam Sung Chan , Baek Il Hyun
Published: August 2020

Acid-activated montmorillonite catalysts were prepared and tested for optimizing CO2 desorption from CO2-rich amine solutions, eventually for energy-efficient CO2 capture.
A highly sensitive quartz crystal microbalance sensor modified with antifouling microgels for saliva glucose monitoring
Authors: Dou Qian , Wang Shiwen , Zhang Zifeng , Wang Yanxiang , Zhao Zhipeng , Guo Haijian , Liu Hongliang , Dai Qing
Published: August 2020

A microgels@amino acids@cross-linked-coated sensor was fabricated to realize saliva glucose detection as well as to provide high resistance to protein pollution.
Activating Co nanoparticles on graphitic carbon nitride by tuning the Schottky barrier via P doping for the efficient dehydrogenation of ammonia-borane
Authors: Xu Shao-Hong , Wang Jing-Feng , Valério Alexsandra , Zhang Wen-Yu , Sun Jia-Lun , He Dan-Nong
Published: August 2020

A highly active Mott–Schottky nanocatalyst for the efficient dehydrogenation of ammonia-borane was constructed by rationally tuning the Schottky barrier of Co/PxCN (P-doped g-C3N4) via simply varying the doping amount of P atoms.
In situ transformation of ZIF-67 into hollow Co2V2O7 nanocages on graphene as a high-performance cathode for aqueous asymmetric supercapacitors
Authors: Le Kai , Gao Mengjiao , Xu Dongmei , Wang Zhou , Wang Guanwen , Lu Guixia , Liu Wei , Wang Fenglong , Liu Jiurong
Published: August 2020

A Co2V2O7/G composite with MOF-derived hollow Co2V2O7 nanocages uniformly distributed on graphene exhibits excellent electrochemical performance for supercapacitors.
Recyclable CPL switch regulated by using an applied DC electric field from chiral nematic liquid crystals (N*-LCs)
Authors: Li Xiaojing , Shen Yihao , Liu Kerui , Quan Yiwu , Cheng Yixiang
Published: August 2020

Recyclable CPL response in N*-LCs could be observed by using the applied DC electric field with EPT effect through texture change. This kind of “on–off–on” system based on DC electric field can adjust gem value and direction of CPL in N*-LCs.
Palladium-catalyzed double-carbonylative cyclization of propargyl alcohols and aryl triflates to expedite construction of 4-aroyl-furan-2(5H)-ones
Authors: Ying Jun , Le Zhengjie , Wu Xiao-Feng
Published: August 2020

A palladium-catalyzed double-carbonylative cyclization of propargyl alcohols and aryl triflates has been developed. Various 4-aroyl-furan-2(5H)-one scaffolds were produced in good yields with Cr(CO)6 as the CO source.
Tailoring desolvation kinetics enables stable zinc metal anodes
Authors: Hou Zhen , Tan Hong , Gao Yao , Li Menghu , Lu Ziheng , Zhang Biao
Published: August 2020

The solvation structure of Zn2+ is regulated through incorporating acetonitrile (AN) into the electrolyte, elevating nucleation sites and stablizing zinc metal anode, as revealed by the complementary theoretical and experimental studies.
High-performance filters from biomimetic wet-adhesive nanoarchitectured networks
Authors: Liu Hui , Zhang Shichao , Liu Lifang , Yu Jianyong , Ding Bin
Published: August 2020

Biomimetic nanofiber-net filters with nano-scale fibers, spider-web-like network structures, and mussel-mimetic wet-adhesive surfaces, were created for high-performance air/water filtration.
A Janus upconverting nanoplatform with biodegradability for glutathione depletion, near-infrared light induced photodynamic therapy and accelerated excretion
Authors: Zhou Hang , Li Qunying , Cheng Xi , Zhang Chao , Sun Jiawei , Du Linyao , Cao Jing , Liu Yajing , Huang Pintong
Published: August 2020

The major limitations of photodynamic therapy (PDT) are the poor tissue penetration of excitation light and the neutralization of reactive oxygen species (ROS) generated by overexpressed glutathione (GSH) in cancer cells.
Structural regulation and optical behavior of three-dimensional metal halide perovskites under pressure
Authors: Shi Yue , Zhou Yu , Ma Zhiwei , Xiao Guanjun , Wang Kai , Zou Bo
Published: August 2020

The high-pressure behaviors of three-dimensional (3D) metal halide perovskites (MHPs) have been summarized in this “scientific dictionary”.
Tuning electronic properties in LaNiO3 thin films by B-site Cu-substitution
Authors: Sønsteby Henrik H. , Skaar Erik , Bratvold Jon E. , Freeland John W. , Yanguas-Gil Angel , Elam Jeffrey W. , Nilsen Ola , Fjellvåg Helmer
Published: August 2020

Cu-Substitution in LaNiO3 by atomic layer deposition provides films spanning six orders of magnitude in resistivity, with metal insulator transition temperatures from 0 K to room temperature.
Testing gravity using galaxy-galaxy lensing and clustering amplitudes in KiDS-1000, BOSS, and 2dFLenS
Authors: Blake Chris , Amon Alexandra , Asgari Marika , Bilicki Maciej , Dvornik Andrej , Erben Thomas , Giblin Benjamin , Glazebrook Karl , Heymans Catherine , Hildebrandt Hendrik , Joachimi Benjamin , Joudaki Shahab , Kannawadi Arun , Kuijken Konrad , Lidman Chris , Parkinson David , Shan HuanYuan , Tröster Tilman , van den Busch Jan Luca , Wolf Christian , Wright Angus H.
Published: August 2020

The physics of gravity on cosmological scales affects both the rate of assembly of large-scale structure and the gravitational lensing of background light through this cosmic web. By comparing the amplitude of these different observational signatures, we can construct tests that can distinguish general relativity from its potential modifications. We used the latest weak gravitational lensing dataset from the Kilo-Degree Survey, KiDS-1000, in conjunction with overlapping galaxy spectroscopic redshift surveys, BOSS and 2dFLenS, to perform the most precise existing amplitude-ratio test. We measured the associated EG statistic with 15 − 20% errors in five Δz = 0.1 tomographic redshift bins in the range 0.2 <  z <  0.7 on projected scales up to 100 h−1 Mpc. The scale-independence and redshift-dependence of these measurements are consistent with the theoretical expectation of general relativity in a Universe with matter density Ωm = 0.27 ± 0.04. We demonstrate that our results are robust against different analysis choices, including schemes for correcting the effects of source photometric redshift errors, and we compare the performance of angular and projected galaxy-galaxy lensing statistics.
Feasibility Study on Installation of Rooftop Photovoltaic System in Complied with Thailand Energy Building Code
Authors: Chiradeja Pathomthat , Ngaopitakkul Atthapol
Published: August 2020

Renewable energy especially solar energy has become a significant part in electrical power generation with its advantage in the environmentally friendly and current trend of decrease in installation cost. The photovoltaic (PV) system on a rooftop is one of the power generating system based on renewable energy that can fit building to utilize space efficiently. This paper is analyzing the feasibility of installing a solar PV rooftop on the building using a case study building located in Bangkok, Thailand. The performance will be evaluated in term of both energy and economic perspective. The comparison with Thailand building energy code also been done to show that overall energy consumption with PV system complies with the law. The result has shown that with rooftop photovoltaic system installation, annual energy consumption in the building can be reduced significantly and it can achieve feasibility in term of economic perspective.
Lens dose and risk of radiation-induced early lens opacities among hospital staff. A cross-sectional study
Authors: Coppeta L. , Spataro A. , Pietroiusti A. , Rizza S. , Perrone S.
Published: August 2020

The main health effect of exposure to ionizing radiation on the eyes is lens opacities and cataracts. Recent findings have raised questions about the pathogenesis of lenticular damage and the exact threshold dose for the onset of this effect. Occupational dose limits for the lens have been therefore recently reduced to 0.02 Gy/year averaged over 5 years with no single year exceeding 0.05 Gy/year. Healthcare workers can be exposed to ionizing radiation during interventional and other medical procedures. The aim of our study was to evaluate the annual dose to the lens in a large group of healthcare workers exposed to ionizing radiation who are working in a university hospital in Rome and to evaluate a dose-response relationship between lens exposure and the onset of lenticular opacities. We reviewed the exposure data of 702 subjects; the average annual dose to the crystalline lens was calculated using a physical algorithm. Moreover, the clinical records of 107 radiation exposed workers were reviewed: the presence of radiation-compatible opacities were assessed for all operators according to the Lens Opacities Classification System (LOCS) III and Merriam-Focht classification. Annual doses exceeding 0.02 Gy were found in 2.1% of the exposed population. Incipient lenticular opacities were observed in 18.6% of the study population. The presence of alterations was associated with higher lens dose (>0.0092 Gy). Based on our results, optimization of procedures and protection of the lens from ionizing radiation by means of personal protection equipment are strongly recommended in higher exposure scenarios.
Allgemeine Übersicht zu Mediastinaltumoren: Einteilung, Zugangswege, Biopsie
Authors: Kirschbaum Andreas
Published: August 2020

Mediastinaltumoren können für das Behandlungsteam hinsichtlich der Diagnostik und Therapie eine echte Herausforderung darstellen. Dies liegt u. a. an dem weiten Spektrum an Tumorarten. Viele Betroffene sind zum Zeitpunkt der Diagnosestellung völlig asymptomatisch trotz erheblicher Tumorgröße. In der räumlichen Zuordnung zu einem mediastinalen Kompartiment kann i. d. R. die Tumorart schon eingeschränkt werden. Ziel ist es jedoch, die Diagnose über eine Punktion oder eine Biopsie zu sichern. Dazu stehen verschiedene Verfahren zur Verfügung. Anhand der räumlichen Lage und der Ausdehnung in der Bildgebung muss der optimale Zugangsweg für die operative Entfernung eines Mediastinaltumors geplant werden. Nur so kann eine risikoarme und komplette Entfernung der Mediastinaltumoren gewährleistet werden.