bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduction in Near‐Surface Wind Speeds With Increasing CO2 May Worsen Winter Air Quality in the Indo‐Gangetic Plain
Authors: Paulot Fabien , Naik Vaishali , W. Horowitz Larry 
Published: September 2022

AbstractWe analyze the relationship between fine particulate matter (PM2.5) and meteorology in winter in the Indo‐Gangetic Plain (IGP). We find that the concentration of PM2.5 exhibits similar increase with decreasing surface wind speed in 15 out of 18 cities considered. Using this observed relationship, we estimate that the reduction of surface wind speed with increasing CO2 simulated by models participating in the Coupled Model Intercomparison Project Phase 6 will result in higher average wintertime PM2.5 concentrations (1% per degree K of global warming) and more frequent high‐pollution events. This observation‐based estimate is qualitatively consistent with the simulated response of black carbon to global warming inferred from the AerChemMIP ssp370SST and ssp370pdSST experiments. We hypothesize that a reduction in the frequency and intensity of western disturbances with increasing CO2 may contribute to the reduction in the surface wind in the IGP.
Satellite Detection of a Massive Phytoplankton Bloom Following the 2022 Submarine Eruption of the Hunga Tonga‐Hunga Haʻapai Volcano
Authors: Barone B. , Letelier R. M. , Rubin K. H. , Karl D. M. 
Published: September 2022

AbstractThe largest submarine volcanic eruption of this century led to a dramatic phytoplankton bloom north of the island of Tongatapu, in the Kingdom of Tonga. In the absence of shipboard observations, we reconstructed the dynamics of this event by using a suite of satellite observations. Two independent bio‐optical approaches confirmed that the phytoplankton bloom was a robust observation and not an optical artifact due to volcanogenic material. Furthermore, the timing, size, and position of the phytoplankton bloom suggest that plankton growth was primarily stimulated by nutrients released from volcanic ash rather than by nutrients upwelled through submarine volcanic activity. The appearance of a large region with high chlorophyll a concentrations <48 hr after the largest eruptive phase indicates a fast ecosystem response to nutrient fertilization. However, net phytoplankton growth probably initiated before the main eruption, when weaker volcanism had already fertilized the ocean.
Melting Experiments on Fe‐O‐H and Fe‐H: Evidence for Eutectic Melting in Fe‐FeH and Implications for Hydrogen in the Core
Authors: Oka Kenta , Ikuta Nagi , Tagawa Shoh , Hirose Kei , Ohishi Yasuo 
Published: September 2022

AbstractWe examined liquidus phase relations in Fe‐O ± H at ∼40 and ∼150 GPa, and in Fe‐H at 45 GPa. While it has been speculated that Fe and FeH form continuous solid solution to core pressures, our experiment on Fe‐H showed that FeH0.20 forms with the hcp structure, different from fcc for stoichiometric FeH, and melts at temperature lower than that for FeH, suggesting eutectic melting between Fe and FeH. It is consistent with the liquidus phase diagram in Fe‐O‐H, which implies the Fe‐FeH binary eutectic liquid composition of FeH0.42 at ∼40 GPa. These experiments also demonstrated the partition coefficient of H between solid Fe and liquid, DH (solid/liquid) = 0.77–0.89. We estimated the outer core liquid composition based on the liquidus phase relations, solid‐liquid partitioning, and outer/inner core densities and velocities, indicating that O and either H or Si are important core light elements.
Nitrogen Isotope Evidence for Changing Arctic Ocean Ventilation Regimes During the Cenozoic
Authors: Knies Jochen 
Published: September 2022

AbstractIn this work, I report on the coupling of dinitrogen (N2) fixation and denitrification in oxygen‐deficient waters of the Arctic Ocean during the Paleogene. This coupling fertilized marine phytoplankton growth and favored organic carbon burial. Reduced vertical mixing due to salinity stratification in a tectonically closed oceanic basin created conditions favorable for N2‐fixation by phytoplankton harboring diazotrophic bacterial symbionts. A positive shift of 5‰ in the δ15N record indicates a change in the main source of biologically available nitrogen due to rapidly changing nutrient availability. I interpret this shift as a switch to Atlantic‐sourced nitrate as the main nitrogen source owing to the opening of the Arctic‐Atlantic gateway to the northern North Atlantic. While the timing of the opening is still disputed among the available Arctic records, I use evidence from the northern North Atlantic to argue that the Arctic Ocean has been fully ventilated since the early Neogene.
Evolving Interior Mixing Regimes in a Tidal River Plume
Authors: Spicer Preston , Huguenard Kimberly , Cole Kelly L. , MacDonald Daniel G. , Whitney Michael M. 
Published: September 2022

AbstractMicrostructure profiling was utilized to estimate vertical mixing (via vertical turbulent buoyancy flux) during a tidal pulse in the interior Merrimack River plume in calm winds. Multiple stratified shear mixing regimes appear and evolve with time. Initially the plume acts as a nearfield jet, with mixing in the plume (plume layer mixing) and over the plume‐ambient interface (nearfield interfacial mixing). As the plume grows, interfacial mixing is suppressed offshore of the nearfield as currents slow, diminishing turbulent exchange between plume and shelf. At the end of ebb, ambient tidal currents reverse direction below plume, initiating another mode of internal, interfacial mixing (coined here as tidal interfacial mixing), allowing exchange between plume and ambient waters offshore. This work highlights previously unreported tidally modulated mixing within the near and midfield of a river plume.
The Value of Probabilistic Prediction for Lightning Ignited Fires
Authors: Di Giuseppe F. 
Published: September 2022

AbstractIn 2021, the availability of a physical model for lightning density prediction at ECMWF led to the development of data driven models to identify episodes conducive of fires. The machine‐learning classifiers worked remarkably well reaching an overall accuracy up to 78%. Still, errors in the lightning forecast substantially reduce the prediction skill. An ensemble of predictions is used to take into account the stochastic nature of the forecast errors. An assessment of the predictive skill in terms of probabilities is performed and is bench‐marked against the deterministic outcome provided by a single deterministic realization. The probabilistic prediction is more skillful than the deterministic one and there is an optimal probability threshold that allows to maximize the correlation between prediction and observed ignitions. Probabilistic forecast also brings the best value for money when a cost‐loss analysis is performed, and a potential economic value is attributed to the forecast.
Hexagonal Prisms Form in Water‐Ice Clouds on Mars, Producing Halo Displays Seen by Perseverance Rover
Authors: Lemmon M. T. , Toledo D. , Apestigue V. , Arruego I. , Wolff M. J. , Patel P. , Guzewich S. , Colaprete A. , Vicente‐Retortillo Á. , Tamppari L. , Montmessin F. , de la Torre Juarez M. , Maki J. , McConnochie T. , Brown A. , Bell J. F. 
Published: September 2022

AbstractObservations by several cameras on the Perseverance rover showed a 22° scattering halo around the Sun over several hours during northern midsummer (solar longitude 142°). Such a halo has not previously been seen beyond Earth. The halo occurred during the aphelion cloud belt season and the cloudiest time yet observed from the Perseverance site. The halo required crystalline water‐ice cloud particles in the form of hexagonal columns large enough for refraction to be significant, at least 11 μm in diameter and length. From a possible 40–50 km altitude, and over the 3.3 hr duration of the halo, particles could have fallen 3–12 km, causing downward transport of water and dust. Halo‐forming clouds are likely rare due to the high supersaturation of water that is required but may be more common in northern subtropical regions during northern midsummer.
Ionic Charge Emission Into Fog From a Remotely Piloted Aircraft
Authors: Harrison R. Giles , Nicoll Keri A. , Marlton Graeme J. , Tilley Douglas J. , Iravani Pejman 
Published: September 2022

AbstractCharge influences the properties of liquid droplets, such as evaporation rates, hydrodynamic stability, and sticking probabilities. Modifying droplet charge therefore provides a possible method of influencing fogs or clouds. An instrumented, remotely piloted aircraft has been equipped with positive and negative corona emitters to cause droplet charging. With the aircraft circling at 20 m altitude, effects of ion release were compared in clear air and natural fog. In clear air, the surface atmospheric electrical field changed whenever the emitters were activated, but without significant differences in the short‐wave radiation as the aircraft passed over previously ionized air. In fog, radiation fluctuations showed a Gaussian distribution before either emitter operated or when both emitters were operating, but with different distributions during unipolar ion emission. Introducing unipolar ions led to a maximum change in fog reflectivity of ∼2%, about 25 s later.
Emirates Mars Ultraviolet Spectrometer's (EMUS) Observation of Argon in the Martian Thermosphere
Authors: Lootah Fatma Hussain , Deighan Justin , Fillingim Matthew , Jain Sonal , Evans J. Scott , Al Matroushi Hessa , Chaffin Michael , Holsclaw Gregory , Lillis Robert , Al Mazmi Hour , Correira John , England Scott 
Published: September 2022

AbstractThe Emirates Mars Ultraviolet Spectrometer (EMUS) is a far ultraviolet spectrometer on‐board the Emirates Mars Mission's (EMM) which arrived at Mars on 9 February 2021. EMUS is designed to observe key neutral species in the Martian thermosphere (100–200 km) and exosphere (≥200 km). EMUS has observed two neutral argon (Ar) emission lines, Ar I 104.8 nm and Ar I 106.6 nm, in the thermosphere. Our interest in these emissions stem from argon's non‐reactiveness, making it a tracer for transport between the upper and lower atmosphere. We report average argon disk brightness measured by EMUS and compare them to measurements from Earth orbiting observatories. For the first time, this work investigates the variability of Ar I 106.6 nm brightness due to emission angles, solar zenith angles, solar longitudes, local times and latitudes. To contrast the behavior of inert argon we compare these results with the photochemically reactive oxygen 135.6 nm.
Relativistic Electron Precipitation by EMIC Waves: Importance of Nonlinear Resonant Effects
Authors: Grach Veronika S. , Artemyev Anton V. , Demekhov Andrei G. , Zhang Xiao‐Jia , Bortnik Jacob , Angelopoulos Vassilis , Nakamura Rumi , Tsai Ethan , Wilkins Colin , Roberts Owen W. 
Published: September 2022

AbstractRelativistic electron losses in Earth's radiation belts are usually attributed to electron resonant scattering by electromagnetic waves. One of the most important wave modes for such scattering is the electromagnetic ion cyclotron (EMIC) mode. Within the quasi‐linear diffusion framework, the cyclotron resonance of relativistic electrons with EMIC waves results in very fast electron precipitation to the atmosphere. However, wave intensities often exceed the threshold for nonlinear resonant interaction, and such intense EMIC waves have been shown to transport electrons away from the loss cone due to the force bunching effect. In this study we investigate if this transport can block electron precipitation. We combine test particle simulations, low‐altitude observations of EMIC‐driven electron precipitation by the Electron Losses and Fields Investigations mission, and ground‐based EMIC observations. Comparing simulations and observations, we show that, despite the low pitch‐angle electrons being transported away from the loss cone, the scattering at higher pitch angles results in the loss cone filling and electron precipitation.
Volcano Monitoring With Magnetic Measurements: A Simulation of Eruptions at Axial Seamount, Kīlauea, Bárðarbunga, and Mount Saint Helens
Authors: Biasi Joseph , Tivey Maurice , Fluegel Bailey 
Published: September 2022

AbstractMonitoring of active volcanic systems is a challenging task due in part to the trade‐offs between collection of high‐quality data from multiple techniques and the high costs of acquiring such data. Here we show that magnetic data can be used to monitor volcanoes by producing similar data to gravimetric techniques at significantly lower cost. The premise of this technique is that magma and wall rock above the Curie temperature are magnetically “transparent,” but not stationary within the crust. Subsurface movements of magma can affect the crustal magnetic field measured at the surface. We construct highly simplified magnetic models of four volcanic systems: Mount Saint Helens (1980), Axial Seamount (2015–2020), Kīlauea (2018), and Bárðarbunga (2014). In all cases, observed or inferred changes to the magmatic system would have been detectable by modern magnetometers. Magnetic monitoring could become common practice at many volcanoes, particularly in developing nations with high volcanic risk.
The Magnetization of an Underwater Caldera: A Time‐Lapse Magnetic Anomaly Study of Axial Seamount
Authors: Fluegel Bailey , Tivey Maurice , Biasi Joseph , Chadwick William W. , Nooner Scott L. 
Published: September 2022

AbstractAxial Seamount in the northeast Pacific erupted in 2015, 2011, and 1998. Although monitored by the Regional Cabled Array of the Ocean Observatory Initiative, few magnetic surveys have been conducted over the region. This study uses high‐resolution magnetic data over the seamount collected by autonomous underwater vehicle Sentry during three years (2015, 2017, and 2020). The goal is to investigate whether there are temporal changes in the near‐surface magnetic field observable over the time scale of one volcanic cycle. We compare magnetic maps from repeated tracklines from each year. We find maps of the yearly difference in magnetization show coherent patterns that are not random. The central region of the caldera has become more magnetic during recent years, suggesting cooling of the surficial lava flows since 2015. Sentry data are more sensitive to shallow crustal structure compared to sea surface data which show longer wavelength anomalies extending deeper into the crust.
Significant Effective Radiative Forcing of Stratospheric Wildfire Smoke
Authors: Liu Cheng‐Cheng , Portmann Robert W. , Liu Shang , Rosenlof Karen H. , Peng Yifeng , Yu Pengfei 
Published: September 2022

AbstractThe radiative forcing (RF) of volcanic sulfate is well quantified. However, the RF of pyrocumulonimbus (pyroCb) smoke with absorbing carbonaceous aerosols has not been considered in climate assessment reports. With the Community Earth System Model, we studied two record‐breaking wildfire events, the 2017 Pacific Northwest Event (PNE) and the 2019–2020 Australian New Year event (ANY), that perturbed stratospheric chemistry and the earth's radiation budget. We calculated a global annual‐mean effective RF (ERF) of −0.04 ± 0.02 and −0.17 ± 0.02 W/m2 at the top of the atmosphere (TOA) for PNE and ANY, respectively. The complexity of longwave RF led to an uncertainty of about 50% in the ERF at the TOA among climate models. We found that modeled ERF from wildfire smoke was 70%–270% more negative than the ERF of mass‐equivalent sulfate aerosol, highlighting its important role in the climate radiative budget.
BepiColombo Mio Observations of Low‐Energy Ions During the First Mercury Flyby: Initial Results
Authors: Harada Yuki , Aizawa Sae , Saito Yoshifumi , André Nicolas , Persson Moa , Delcourt Dominique , Hadid Lina Z. , Fraenz Markus , Yokota Shoichiro , Fedorov Andréi , Miyake Wataru , Penou Emmanuel , Barthe Alain , Sauvaud Jean‐André , Katra Bruno , Matsuda Shoya , Murakami Go 
Published: September 2022

AbstractWe present initial results of low‐energy ion observations from BepiColombo's first Mercury flyby. Unprecedentedly high time resolution measurements of low energy ions at Mercury by BepiColombo Mio reveal rapid (a few seconds) and large (1–2 orders of magnitude) fluctuations of ion flux around the magnetopause and within the magnetosphere. Around the magnetic equator in the pre‐midnight magnetotail, Mio observed plasma sheet ions consistent with previous observations. In the midnight magnetotail near the closest approach, Mio observed the co‐existence of high‐energy (∼keV/q) and low‐energy (<∼300 eV/q) ion components. The low‐energy component is inferred to be cold with a temperature well below 100 eV and have a major contribution to the total density as opposed to previously reported cold tenuous ions. Future observations by Mio will provide insights into the sources, transport, and acceleration of the newly identified ion components.
Hydrogen Relative Permeability Hysteresis in Underground Storage
Authors: Lysyy Maksim , Føyen Tore , Johannesen Else Birkeland , Fernø Martin , Ersland Geir 
Published: September 2022

AbstractImplementation of the hydrogen economy for emission reduction will require storage facilities, and underground hydrogen storage (UHS) in porous media offers a readily available large‐scale option. Lack of studies on multiphase hydrogen flow in porous media is one of the several barriers for accurate predictions of UHS. This paper reports, for the first time, measurements of hysteresis in hydrogen‐water relative permeability in a sandstone core under shallow storage conditions. We use the steady state technique to measure primary drainage, imbibition and secondary drainage relative permeabilities, and extend laboratory measurements with numerical history matching and capillary pressure measurements to cover the whole mobile saturation range. We observe that gas and water relative permeabilities show strong hysteresis, and nitrogen as substitute for hydrogen in laboratory assessments should be used with care. Our results serve as calibrated input to field scale numerical modeling of hydrogen injection and withdrawal processes during porous media UHS.
Day‐to‐Day Variability of the Semidiurnal Tide in the F‐Region Ionosphere During the January 2021 SSW From COSMIC‐2 and ICON
Authors: Oberheide J. 
Published: September 2022

AbstractThe semidiurnal tidal spectrum in the F‐region ionosphere obtained from hourly COSMIC‐2 Global Ionospheric Specification (GIS) data assimilation is greatly (>50%) enhanced during the January 2021 Sudden Stratospheric Warming (SSW). Moreover, the semidiurnal migrating tidal response in topside electron densities closely follows the day‐to‐day changes of the 10 hPa, 60°N zonal wind from MERRA‐2 during the SSW. The response is similar in the northern and southern crests of the Equatorial Ionization Anomaly (EIA) but persists toward higher magnetic latitudes and the EIA trough. A slight phase shift toward earlier local times is consistent with theoretical expectations of an E‐region dynamo driving and agrees with semidiurnal tidal diagnostics of MIGHTI/ICON zonal winds at 105 km. COSMIC‐2 GIS are the first data set to resolve the tidal weather of the ionosphere on a day‐to‐day basis and, therefore, provide a new perspective on space weather variability driven by lower and middle atmosphere dynamics.
Hadley Cell Edge Modulates the Role of Ekman Heat Flux in a Future Climate
Authors: Hasan Mahdi , Larson Sarah , McMonigal Kay 
Published: September 2022

AbstractIn a future climate, the Hadley cell and associated trade easterlies are projected to expand poleward. This projected change in the atmospheric circulation is expected to impact the ocean through changes in the mean sea surface temperature (SST). We also expect implications for the large‐scale SST variability, because near‐surface wind is directly related to two drivers of the SST, that is, turbulent heat flux and anomalous wind‐driven Ekman heat flux. Previous studies show that in the subtropics, anomalous turbulent and Ekman heat fluxes oppose each other, acting to reduce SST variability, whereas, in the midlatitudes, they reinforce each other and enhance SST variability. Through analysis of reanalysis products and Coupled Model Intercomparison Project simulations, we find that the subtropical regions where the fluxes oppose each other are projected to expand poleward in a future climate, following the poleward expansion of the Hadley cell, with potential implications for the amplitude of subtropical SST variability.
Droughts, Pluvials, and Wet Season Timing Across the Chao Phraya River Basin: A 254‐Year Monthly Reconstruction From Tree Ring Widths and δ18O
Authors: Nguyen Hung T. T. , Galelli Stefano , Xu Chenxi , Buckley Brendan M. 
Published: September 2022

AbstractWater system operations require subannual streamflow data—e.g., monthly or weekly—that are not readily achievable with conventional streamflow reconstructions from annual tree rings. This mismatch is particularly relevant to highly seasonal rivers such as Thailand's Chao Phraya. Here, we combine tree ring width and stable oxygen isotope ratios (δ18O) from Southeast Asia to produce 254‐year, monthly‐resolved reconstructions for all four major tributaries of the Chao Phraya. From the reconstructions, we derive subannual streamflow indices to examine past hydrological droughts and pluvials, and find coherence and heterogeneity in their histories. The monthly resolution reveals the spatiotemporal variability in wet season timing, caused by interactions between early summer typhoons, monsoon rains, catchment location, and topography. Monthly‐resolved reconstructions, like the ones presented here, not only broaden our understanding of past hydroclimatic variability, but also provide data that are functional to water management and climate‐risk analyses, a significant improvement over annual reconstructions.
Auroral Spiral Structure Formation Through Magnetic Reconnection in the Auroral Acceleration Region
Authors: Huang Kai , Liu Yi‐Hsin , Lu Quanming , Hu Zejun , Lynch Kristina A. , Hesse Michael , Vaivads Andris , Yang Huigen 
Published: September 2022

AbstractAuroral spiral is one of the auroral vortex structures. Here, we propose a model to explain the formation of auroral spiral structure based on three‐dimensional particle‐in‐cell simulations. In our model, an auroral arc develops through precipitations of electrons accelerated during magnetic reconnection in the auroral acceleration region. The arc morphology at low altitudes can be modified by electron‐scale magnetic flux ropes, which are generated through secondary oblique tearing modes in the intensified current sheet along one particular branch of the primary reconnection separatrices. The resulting vortex structures agree well with high‐resolution observations of auroral spirals. We find that the rotational sense of these spirals is determined by electron kinetic processes and controlled by the guide field direction. Our study further suggests that when the field‐aligned length of the auroral acceleration region is shorter than a critical length, these auroral spiral structures will not form.