bluuebunny/crossref_metadata_2025 huggingface dataset:
An Updated Model Providing Long‐Term Data Sets of Energetic Electron Precipitation, Including Zonal Dependence
Authors: van de Kamp M. , Rodger C. J. , Seppälä A. , Clilverd M. A. , Verronen P. T.
Published: August 2018

In this study 30‐ to 1,000‐keV energetic electron precipitation (EEP) data from low Earth orbiting National Oceanic and Atmospheric Administration and MetOp Polar Orbiting Environmental Satellites were processed in two improved ways, compared to previous studies. First, all noise‐affected data were more carefully removed, to provide more realistic representations of low fluxes during geomagnetically quiet times. Second, the data were analyzed dependent on magnetic local time (MLT), which is an important factor affecting precipitation flux characteristics. We developed a refined zonally averaged EEP model, and a new model dependent on MLT, which both provide better modeling of low fluxes during quiet times. The models provide the EEP spectrum assuming a power law gradient. Using the geomagnetic index Ap with a time resolution of 1 day, the spectral parameters are provided as functions of the L shell value relative to the plasmapause. Results from the models compare well with EEP observations over the period 1998–2012. Analysis of the MLT‐dependent data finds that during magnetically quiet times, the EEP flux concentrates around local midnight. As disturbance levels increase, the flux increases at all MLT. During disturbed times, the flux is strongest in the dawn sector and weakest in the late afternoon sector. The MLT‐dependent model emulates this behavior. The results of the models can be used to produce ionization rate data sets over any time period for which the geomagnetic Ap index is available (recorded or predicted). This ionization rate data set will enable simulations of EEP impacts on the atmosphere and climate with realistic EEP variability.
The Role of Ligninolytic Enzymes Laccase and a Versatile Peroxidase of the White‐Rot Fungus Lentinus tigrinus in Biotransformation of Soil Humic Matter: Comparative In Vivo Study
Authors: Zavarzina A. G. , Lisov A. V. , Leontievsky A. A.
Published: August 2018

Soil organic matter (SOM) turnover by ligninolytic fungi is a large‐scale process that controls organic carbon geochemistry in terrestrial ecosystems. However, the role of certain oxidative enzymes (e.g., laccase) in humus degradation remains unclear, as well as the molecular structure and recalcitrance of SOM components. In order to address these questions, the degradation of forest soil humic acid (HA) in the presence of laccase and a versatile peroxidase (VP) has been studied in the liquid culture of Lentinus tigrinus. Contrary to the evolving views on humus structure, we have found that alkali‐extractable and acid‐insoluble constituents of SOM (HA) contain true macromolecular components, stable in the presence of 0.1% sodium dodecyl sulfate but degradable/resynthesizable by oxidative enzymes acting on covalent linkages. The HA degradation in the presence of laccase (high N medium) occurs at slower initial rate than in the presence of VP (low N medium). However, each of the enzymes caused about 60% color loss and almost complete degradation of HA into smaller molecules (gel‐filtration data) within 2 weeks of cultivation. Depolymerization of HA in the culture liquid in the presence of laccase was accompanied by polymerization of degradation products on mycelium. Our results show that (1) humus macromolecules are not stable to oxidative enzymes once desorbed from the mineral phase, (2) laccase of Lentinus tigrinus is comparable by its degradation potential to VP, and (3) interfacial secondary synthesis reactions occur during humus decay in the presence of laccase. Our results highlight the important role of laccases in SOM sequestration in soils.
Physical State and Structure of the Crust Beneath the Western‐Central United States From Multiobservable Probabilistic Inversion
Authors: Tork Qashqai Mehdi , Afonso Juan Carlos , Yang Yingjie
Published: August 2018

The Southern Rocky Mountains (SRM) have the highest regional elevations, but a comparable crustal thickness to that of the Great Plains. Isolating the contributions of the crust and upper mantle in supporting the topography of the SRM has been a topic of considerable controversy for the past two decades, leading to contrasting hypotheses. In order to constrain the relative contributions from the crust and mantle, reliable models of the physical state of the crust and upper mantle are necessary. Here we employ a recently developed multiobservable Bayesian inversion approach to study the present‐day physical state (i.e., Vs,Vp, density, Vp/Vs, crustal thickness, and temperature) of the crust in a region encompassing the western‐central United States. We image highly heterogeneous temperature and compositional structures, which combine in a nonintuitive way with total crustal thickness to create the observed topography and control other geophysical signatures. In the SRM, topography is supported by a combination of crustal and mantle contributions. South of 38°N, mantle sources (both static and dynamic) constitute the main support to the high elevations, whereas to the north of this latitude, crustal structure provides the main contribution. In the Colorado Plateau, Arizona transition zone, and Basin and Range provinces, most of the topography seems to be supported by mantle sources (within the lithospheric mantle and/or dynamic). At middle to lower crustal depths beneath the SRM, we image high temperatures, high Vp/Vs values, anomalously low crustal velocities, and low densities. These observations correlate with high electrical conductivities and the location of recent volcanism, suggesting the occurrence of melt/fluids. We do not find low Vp/Vs values at middle/low crustal depths beneath the SRM that may suggest felsic, weak lithologies.
A Subgrid Approach for Modeling Microtopography Effects on Overland Flow
Authors: Jan Ahmad , Coon Ethan T. , Graham Jake D. , Painter Scott L.
Published: August 2018

Microtopography, or heterogeneities in the elevation across scales much smaller than the domain of interest, plays a critical role in surface water retention, surface/subsurface interactions, and runoff. Resolving microtopographic influences on flow requires high‐resolution simulations that are computationally demanding even when considering the surface system in isolation and even more so when surface flow is one component in integrated simulations that couple surface flow with unsaturated subsurface flow. There is thus significant motivation for models that allow the effects of subgrid microtopography to be better represented. Subgrid models modify coarsened models to capture the microtopography‐induced nonlinear effects on hydrologic processes. We present a subgrid model that alters the water storage and flow terms in the diffusion wave equation for surface flow. Stochastically generated microtopography with strongly contrasting spatial structure, high‐resolution digital elevation maps from a polygonal tundra site on the North Slope of Alaska and a hummocky microtopography from a field site in Northern Minnesota are used to assess the accuracy and applicability of the subgrid model to disparate landscapes. Approaches for determining subgrid model parameters are tested and simulation results using the subgrid model are compared to benchmark fine‐scale simulations and to coarse simulations that ignore microtopography. Our findings confirm that a properly parameterized subgrid model greatly improves the coarse‐scale representation of hydrographs and total water content in the system. Using the polygonal tundra example, we propose and test a strategy for moving to application‐relevant spatial scales by combining microtopography classification and a few fine‐scale simulations on small subdomains.
The Impact of Aquifer Flushing on Groundwater Arsenic Across a 35‐km Transect Perpendicular to the Upper Brahmaputra River in Assam, India
Authors: Choudhury R. , Nath B. , Khan M. R. , Mahanta C. , Ellis T. , van Geen A.
Published: August 2018

Well testing in the floodplain of the Brahmaputra River in Golaghat and Jorhat districts of Assam, India, shows that groundwater arsenic (As) concentrations increase with distance from the river. To establish the origin of this pattern, an additional 900 wells <60‐m deep were tested for As and nine sites were drilled along a 35‐km transect perpendicular to the river. The field data show no relation between groundwater As concentrations ranging from <1 to 660 μg/L along the transect and (a) As concentrations of <1–5 mg/kg in cuttings of aquifer sand recovered while drilling or (b) the degree of reduction of iron oxides in these cuttings. The drilling indicates, however, a marked increase in the thickness of a clay layer capping the aquifer starting from <1–5 m near the river to over 60 m at the most distant site toward the base of the Naga foothills. Organic radiocarbon ages of 18–46 kyr obtained from all but one of 13 clay samples indicate pre‐Holocene deposition of the underlying sands across the entire transect. Radiocarbon ages of dissolved inorganic carbon of 0.2, 4.7, and 17.8 kyr were measured in groundwater from three monitoring wells installed to 30–60‐m depth at distances of 10, 20, and 40 km from the river, respectively. A conceptual groundwater flow model consistent with monitored heads and groundwater ages suggests that thick clay layers capping the aquifer further from the river inhibited flushing of the aquifer and, as a result, preserved higher As levels in groundwater.
How Two Massive Space Storms Zapped Alaska
Authors: Underwood Emily
Published: August 2018

New study reveals how space weather causes rapid fluctuations in Earth’s surface geomagnetic field.
Audio Reveals Sizes of Methane Bubbles Rising from the Seafloor
Authors: Kornei Katherine
Published: August 2018

A sensitive underwater microphone captures the sounds of methane, a potent greenhouse gas, escaping into waters off the coast of Oregon. Using this sound, researchers can estimate the bubbles’ sizes.
Recent Acceleration of a Rock Glacier Complex, Ádjet, Norway, Documented by 62 Years of Remote Sensing Observations
Authors: Eriksen H. Ø. , Rouyet L. , Lauknes T. R. , Berthling I. , Isaksen K. , Hindberg H. , Larsen Y. , Corner G. D.
Published: August 2018

Recent acceleration of rock glaciers is well recognized in the European Alps, but similar behavior is hardly documented elsewhere. Also, the controlling factors are not fully understood. Here we provide evidence for acceleration of a rock glacier complex in northern Norway, from 62 years of remote sensing data. Average annual horizontal velocity measured by aerial feature tracking increased from ~0.5 myr−1 (1954–1977) to ~3.6 myr−1 (2006–2014). Measured by satellite synthetic aperture radar offset‐tracking, averages increased from ~4.9 to ~9.8 myr−1 (2009–2016) and maximum velocities from ~12 to ~69 myr−1. Kinematic analysis reveals different spatial‐temporal trends in the upper and the lower parts of the rock glacier complex, suggesting progressive detachment of the faster front. We suggest that permafrost warming, topographic controls, and increased water access to deeper permafrost layers and internal shear zones can explain the kinematic behavior.
On the Limits of CALIOP for Constraining Modeled Free Tropospheric Aerosol
Authors: Watson‐Parris Duncan , Schutgens Nick , Winker David , Burton Sharon P. , Ferrare Richard A. , Stier Philip
Published: August 2018

The spaceborne Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument provides valuable information on the vertical distribution of global aerosol and is often used to evaluate vertical aerosol distributions in general circulation models (GCMs). Here we show, however, that the detection limit of the CALIOP retrievals mean background aerosol is not detected, leading to substantially skewed statistics that moreover differ significantly by product. In the CALIOP Level 2 product this missing low‐backscatter aerosol results in the retrieved aerosol distribution significantly overrepresenting aerosol backscatter and extinction in the middle and upper troposphere if taken to be representative of the undetected aerosol. The CALIOP Level 3 product assumes no aerosol where none is detected, which then leads to an underestimation in the aerosol extinction profile in the upper troposphere. Using the ECHAM‐HAM GCM, we estimate that the mean fraction of aerosol undetected by CALIOP daytime (nighttime) retrievals is 41% (44%) globally.
Dome Collapse Interaction With the Atmosphere
Authors: Barfucci G. , Ripepe M.
Published: August 2018

Dome collapse is a dramatic volcanic process, yet the dynamics and evolution of dome collapse still present open questions. Observational data are rare, and this limits our ability to interpret the evolution of this phenomenon in terms of risk assessment. We show how the partial dome collapse of Soufrière Hills Volcano on 2010 evolved in less than 45 min and was characterized by five main different episode of dome failure process. Time and amplitude of seismic and infrasonic records associated with successive pyroclastic density currents show a nearly quadratic temporal trend suggesting a self‐accelerating process increasing in intensity up to the failure limit. Each episode generated gravity waves in the atmosphere, representing the first evidence of internal waves formed due to propagation of density currents in stratified fluids. Finally, we use gravity waves to estimate the total erupted mass and the plume height of the Vulcanian explosions triggered by the decompression induced by the collapse.
Evidence for Predictive Skill of High‐Latitude Climate Due to Midsummer Sea Ice Extent Anomalies
Authors: He Shengping , Knudsen Erlend M. , Thompson David W. J. , Furevik Tore
Published: August 2018

Previous work has explored the linkages between Arctic sea ice extent (SIE) anomalies at the end of the summer melt season and high‐latitude climate. Here we show that Arctic midsummer SIE anomalies provide predictive skill on time scales of ~2–3 months for high‐latitude climate. Midsummers characterized by low SIE are associated with significant positive temperature and easterly wind anomalies throughout the high‐latitude troposphere through September and significant positive temperature anomalies at the Arctic surface into October. The inferred predictive skill for autumn climate derives from the persistence of the sea ice field. It is robust throughout the Arctic basin and is supported in climate models from the fifth phase of the Coupled Model Intercomparison Project archive and in prediction experiments from the Arctic Predictability and Prediction on Seasonal to Interannual Time scales project. It is theorized that the predictive skill derives from (1) the anomalous storage of heat in the Arctic Ocean during periods of low summertime SIE and (2) the delayed formation of sea ice during the following autumn months.
Electron Energization at a Reconnecting Magnetosheath Current Sheet
Authors: Eriksson Elin , Vaivads Andris , Graham Daniel B. , Divin Andrey , Khotyaintsev Yuri V. , Yordanova Emiliya , André Mats , Giles Barbara L. , Pollock Craig J. , Russell Christopher T. , Contel Olivier Le , Torbert Roy B. , Ergun Robert E. , Lindqvist Per‐Arne , Burch James L.
Published: August 2018

We present observations of electron energization within a sub‐ion‐scale magnetosheath current sheet (CS). A number of signatures indicate ongoing reconnection, including the thickness of the CS (∼0.7 ion inertial length), nonzero normal magnetic field, Hall magnetic fields with electrons carrying the Hall currents, and electron heating. We observe localized electron acceleration and heating parallel to the magnetic field at the edges of the CS. Electrostatic waves observed in these regions have low phase velocity and small wave potentials and thus cannot provide the observed acceleration and heating. Instead, we find that the electrons are accelerated by a parallel potential within the separatrix regions. Similar acceleration has been reported based on magnetopause and magnetotail observations. Thus, despite the different plasma conditions in magnetosheath, magnetopause, and magnetotail, the acceleration mechanism and corresponding heating of electrons is similar.
Impact of Short‐Term Climate Variability on Volatile Organic Compounds Emissions Assessed Using OMI Satellite Formaldehyde Observations
Authors: Stavrakou T. , Müller J.‐F. , Bauwens M. , De Smedt I. , Van Roozendael M. , Guenther A.
Published: August 2018

A major feedback between climate and atmospheric chemistry lies in the meteorological dependence of the emissions of biogenic volatile organic compounds (BVOCs), precursors of important climate forcers, aerosols, and ozone. Whereas the short‐term response of BVOC emissions to meteorological drivers is fairly well simulated by current emission models, it is yet unclear whether models can faithfully predict their response to climate change, given the scarcity of long observation records of BVOC fluxes. Here we take advantage of the high yield of formaldehyde (HCHO) in the oxidation of VOCs and use a long‐term spaceborne record of HCHO observations in combination with model simulations to show that (i) HCHO interannual variability is primarily driven by climate through its impacts on photochemistry, vegetation fire occurrence, and above all, biogenic emissions and (ii) the HCHO record validates the interannual variability of biogenic emissions calculated by the state‐of‐the‐art Model of Emissions of Gases and Aerosols from Nature (MEGAN) emission model in vegetated regions.
Locally Enhanced Aerosols Over a Shipping Lane Produce Convective Invigoration but Weak Overall Indirect Effects in Cloud‐Resolving Simulations
Authors: Blossey Peter N. , Bretherton Christopher S. , Thornton Joel A. , Virts Katrina S.
Published: August 2018

The effect of aerosol emissions from an active shipping lane in the Indian Ocean is simulated using an idealized framework in a cloud‐resolving model. Increased aerosol concentrations over the modeled shipping lane lead to increased cloud droplet number, cloud liquid mass, ice hydrometeor mass, and simulated radar reflectivity. The invigoration of deep convection induces mesoscale uplift and increased precipitation over the shipping lane. A predicted increase in the prevalence of both strong updrafts and radar echoes aloft is suggestive of enhanced lightning activity over the shipping lane, as observed in a recent study. Cloud radiative effects, both shortwave and longwave, are intensified over the shipping lane, but the change in the net radiative flux at top of atmosphere is not significantly different from zero.
Distribution of Vapor and Condensate in a Hydrothermal System: Insights From Self‐Potential Inversion at Mount Tongariro, New Zealand
Authors: Miller C. A. , Kang S. G. , Fournier D. , Hill G.
Published: August 2018

Inversion of self‐potential data for source current density, js, in complex volcanic settings, yields hydrological information without the need for a prior groundwater flow model; js contains information about pH, pore saturation, and permeability, from which we infer the distribution of liquid and vapor phases. To understand the hydrothermal flow dynamics and hydraulic connectivity between surface thermal features at Mount Tongariro volcano, New Zealand, we undertook a reconnaissance scale self‐potential survey and developed an inversion routine for js, constrained by an existing 3‐D conductivity model from magnetotelluric measurements. The 3‐D distribution of js at Mount Tongariro reveals a discontinuous zero js zone interpreted as vapor or residually saturated pore space, surrounded by low to moderate js interpreted as circulating condensate liquid. Bounding faults act as conduits for down flowing groundwater or condensate, as well as barriers for the hydrothermal system. Localized small‐scale circulation associated with individual surface thermal features, rather than a single circulating system, accounts for the lack of widespread anomalous geochemical observations prior to the 2012 Te Maari eruption.
Global Freshwater Availability Below Normal Conditions and Population Impact Under 1.5 and 2 °C Stabilization Scenarios
Authors: Liu Wenbin , Lim Wee Ho , Sun Fubao , Mitchell Dann , Wang Hong , Chen Deliang , Bethke Ingo , Shiogama Hideo , Fischer Erich
Published: August 2018

Based on the large ensembles of the half a degree additional warming, prognosis, and projected impacts historical, +1.5 and +2 °C experiments, we quantify changes in the magnitude of water availability (i.e., precipitation minus actual evapotranspiration; a function of monthly precipitation flux, latent heat flux, and surface air temperature) below normal conditions (less than median, e.g., 20th percentile water availability). We found that, relative to the historical experiment, water availability below normal conditions of the +1.5 and +2 °C experiments would decrease in the midlatitudes and the tropics, indicating that hydrological drought is likely to increase in warmer worlds. These cause more (less) people in East Asia, Central Europe, South Asia, and Southeast Asia (West Africa and Alaska/Northwest Canada) to be exposed to water shortage. Stabilizing warming at 1.5 °C instead of 2 °C would limit population impact in most of the regions, less effective in Alaska/Northwest Canada, Southeast Asia, and Amazon. Globally, this reduced population impact is ~117 million people.
Controls on Open‐Ocean North Atlantic ΔpCO2 at Seasonal and Interannual Time Scales Are Different
Authors: Henson Stephanie A. , Humphreys Matthew P. , Land Peter E. , Shutler Jamie D. , Goddijn‐Murphy Lonneke , Warren Mark
Published: August 2018

The North Atlantic is a substantial sink for anthropogenic CO2. Understanding the mechanisms driving the sink's variability is key to assessing its current state and predicting its potential response to global climate change. Here we apply a time series decomposition technique to satellite and in situ data to examine separately the factors (both biological and nonbiological) that affect the sea‐air CO2 difference (ΔpCO2) on seasonal and interannual time scales. We demonstrate that on seasonal time scales, the subpolar North Atlantic ΔpCO2 signal is predominantly correlated with biological processes, whereas seawater temperature dominates in the subtropics. However, the same factors do not necessarily control ΔpCO2 on interannual time scales. Our results imply that the mechanisms driving seasonal variability in ΔpCO2 cannot necessarily be extrapolated to predict how ΔpCO2, and thus the North Atlantic CO2 sink, may respond to increases in anthropogenic CO2 over longer time scales.
New High‐Pressure Forms of Al2SiO5
Authors: Zhou Y. , Irifune T. , Ohfuji H. , Kuribayashi T.
Published: August 2018

Phase relations of Al2SiO5 have been studied by multianvil experiments at pressures of 13–23 GPa and temperatures of 2000–2900 K. Al2SiO5 kyanite was found to transform into two new high‐pressure forms of Al2SiO5 (kyanite II and III) at temperatures exceeding 2300–2500 K and pressures of 14–23 GPa: The first phase transition occurs near 14 GPa, and the second occurs near 17 GPa. The new Al2SiO5 phases have triclinic and monoclinic crystal symmetries with zero‐pressure densities of 3.876(2) and 3.982(1) g/cm3, respectively, which are significantly denser than kyanite (ρ0 = 3.666 g/cm3) but less dense than the isochemical mixture of Al2O3 corundum and SiO2 stishovite (ρ0 = 4.036 g/cm3). The exceptionally high stability temperatures of the new Al2SiO5 phases suggest that they are unlikely to form in the present mantle but may be found in some impact craters and shocked meteorites and act as important indicators of pressure and temperature for the shock events.
Two‐Dimensional Particle‐in‐Cell Simulation of Magnetosonic Wave Excitation in a Dipole Magnetic Field
Authors: Chen Lunjin , Sun Jicheng , Lu Quanming , Wang Xueyi , Gao Xinliang , Wang Dedong , Wang Shui
Published: August 2018

The excitation of magnetosonic waves in the meridian plane of a rescaled dipole magnetic field is investigated, for the first time, using a general curvilinear particle‐in‐cell simulation. Our simulation demonstrates that the magnetosonic waves are excited near the equatorial plane by tenuous ring distribution protons. The waves propagate nearly perpendicularly to the background magnetic field along both radially inward and outward directions. Different speeds of inward and outward propagation result in the asymmetrical distribution about the source region. The waves are accompanied by energization of both cool protons and electrons near the wave source region. The cool protons are heated perpendicularly, while the cool electrons can be heated in the parallel direction and also experience enhanced perpendicular drift at the presence of intense wave power. The implications of simulation results to the observations of magnetosonic waves and related particle heating in the inner magnetosphere are also discussed.
Generation of Lower Harmonic Magnetosonic Waves Through Nonlinear Wave‐Wave Interactions
Authors: Gao Xinliang , Sun Jicheng , Lu Quanming , Chen Lunjin , Wang Shui
Published: August 2018

Although magnetosonic waves in the Earth's magnetosphere have been well understood by the linear theory, low harmonic magnetosonic waves, which often lack of free energy, can be unusually present. By employing a 1‐D particle‐in‐cell simulation model, we have investigated the generation of those unusual lower harmonic magnetosonic waves in a plasma containing a proton ring distribution. In our simulation, the higher harmonic magnetosonic waves (from~9Ωh to ~12Ωh) are firstly excited due to the unstable proton ring, which can be well explained by the linear theory. Several lower harmonic magnetosonic waves (below 5Ωh), which well separates away from the higher harmonics, soon appear in the system. Those lower harmonics, which do not have any positive linear growth rates, can be generated by a nonlinear mechanism. The bicoherence analysis demonstrates that there is a strong phase coupling among the unusual lower harmonic magnetosonic waves and the magnetosonic waves generated due to the proton ring, supporting the idea that the lower harmonic waves could be driven by the wave‐wave couplings of the generated magnetosonic waves. This wave‐wave coupling generation mechanism is further confirmed by another two simulations, where two or three pump magnetosonic waves are initially injected. The lower‐frequency waves, that is, the fundamental wave and its second harmonic, are also successfully reproduced due to the nonlinear coupling of pump magnetosonic waves. Our simulations not only propose a potential generation mechanism of unusual lower harmonic magnetosonic waves in the Earth's magnetosphere, but also give some new insights on the evolution of magnetosonic spectra.
Observations and Impacts of the 10 September 2017 Solar Events at Mars: An Overview and Synthesis of the Initial Results
Authors: Lee C. O. , Jakosky B. M. , Luhmann J. G. , Brain D. A. , Mays M. L. , Hassler D. M. , Holmström M. , Larson D. E. , Mitchell D. L. , Mazelle C. , Halekas J. S.
Published: August 2018

On 10 September 2017, some of the strongest solar activity occurred in association with active region 12673 (AR2673), including an X‐class solar flare and a fast coronal mass ejection. Although AR2673 was not centrally facing Mars, the activity impacted the local space weather conditions at Mars. We give an overview of observations obtained from the Mars Atmosphere and Volatile EvolutioN, Mars Science Laboratory, and Mars Express missions. Numerical results from the Wang‐Sheeley‐Arge (WSA)‐Enlil‐cone model together with Earth/L1 and STEREO‐A observations are also presented to provide some heliospheric context. We discuss the initial results on the space weather impacts at Mars, which include heating of the upper atmosphere by solar flare emissions, flare‐related enhancements of ion and neutral densities, solar energetic particles impacting the atmosphere and surface, bright emissions of a diffuse (global) aurora, deeply penetrating interplanetary magnetic fields over the Martian dayside, and enhanced atmospheric escape rates.
Impact of Aerosol‐PBL Interaction on Haze Pollution: Multiyear Observational Evidences in North China
Authors: Huang Xin , Wang Zilin , Ding Aijun
Published: August 2018

Atmospheric aerosols have been found to influence the development of planetary boundary layer (PBL) and hence to enhance haze pollution in megacities. Previous works on aerosol‐PBL interaction were mainly based on model simulation for short‐term cases; so far, there is a lack of long‐term observational evidences. In this study, based on multiyear measurements and reanalysis meteorological data, we give observational evidences on aerosol‐PBL interaction and its impact on pollution aggravation. We found a significant heating in upper PBL with maximum temperature change about 0.7 °C on average and a substantial dimming near surface with a mean temperature drop of −2.2 °C under polluted condition. By integrating Eulerian forward simulation and Lagrangian backward trajectory calculation, we demonstrated that the atmospheric heating was mainly induced by light‐absorbing aerosols like black carbon. Then an index representing such effect was proposed, which could well characterize aerosol‐PBL interaction and its impact on air pollution.
Basal Melt and Freezing Rates From First Noble Gas Samples Beneath an Ice Shelf
Authors: Huhn Oliver , Hattermann Tore , Davis Peter E. D. , Dunker Erich , Hellmer Hartmut H. , Nicholls Keith W. , Østerhus Svein , Rhein Monika , Schröder Michael , Sültenfuß Jürgen
Published: August 2018

A climatically induced acceleration in ocean‐driven melting of Antarctic ice shelves would have consequences for both the discharge of continental ice into the ocean and thus global sea level, and for the formation of Antarctic Bottom Water and the oceanic meridional overturning circulation. Using a novel gas‐tight in situ water sampler, noble gas samples have been collected from six locations beneath the Filchner Ice Shelf, the first such samples from beneath an Antarctic ice shelf. Helium and neon are uniquely suited as tracers of glacial meltwater in the ocean. Basal meltwater fractions range from 3.6% near the ice shelf base to 0.5% near the sea floor, with distinct regional differences. We estimate an average basal melt rate for the Filchner‐Ronne Ice Shelf of 177 ± 95 Gt/year, independently confirming previous results. We calculate that up to 2.7% of the meltwater has been refrozen, and we identify a local source of crustal helium.
Statistical Characteristics of Polar Cap Patches Observed by RISR‐C
Authors: Ren Jiaen , Zou Shasha , Gillies Robert G. , Donovan Eric , Varney Roger H.
Published: August 2018

Polar cap “patches” are ~100 to 1,000 km islands of high‐density plasma at polar latitudes, which can cause scintillation to communication and navigation signals. An automatic algorithm for patch identification has been developed and applied to the observations from the Resolute Bay Incoherent Scatter Radar‐Canada during January to March and September to December, 2016. Four hundred thirty‐seven patches have been identified, and their statistical characteristics have been studied, including their occurrence rate as a function of magnetic local time (MLT) and statistical profiles of plasma parameters at different MLT sectors. About 60% of the patches are observed between 1200 and 2400 MLT, consistent with earlier observations near this latitude (~82° MLat) using different instruments. Superposed epoch analysis has been used to study the vertical profiles of electron density and temperature, ion temperature, vertical velocity, and flux measured within the patches where the density peaks. The patch median density is higher than the sector median with a ratio of ~1.8–2.1 at the altitude of F‐region density peak. Meanwhile, the patch electron temperature is typically lower than the sector median between ~200 and 450 km with the largest difference near noon (~380 K). In contrast, the ion temperature profile of the patches does not show obvious differences except in the noon sector, where the ion temperature is about 150 K higher than the sector median at ~360 km. Additionally, downward ion fluxes with peak exceeding ~1013 m−2 s−1 are found in the patches between ~200 and 400 km at all MLT sectors.
Variability and Redistribution of Heat in the Atlantic Water Boundary Current North of Svalbard
Authors: Renner A. H. H. , Sundfjord A. , Janout M. A. , Ingvaldsen R. B. , Beszczynska‐Möller A. , Pickart R. S. , Pérez‐Hernández M. D.
Published: August 2018

We quantify Atlantic Water heat loss north of Svalbard using year‐long hydrographic and current records from three moorings deployed across the Svalbard Branch of the Atlantic Water boundary current in 2012–2013. The boundary current loses annually on average 16 W m−2 during the eastward propagation along the upper continental slope. The largest vertical fluxes of >100 W m−2 occur episodically in autumn and early winter. Episodes of sea ice imported from the north in November 2012 and February 2013 coincided with large ocean‐to‐ice heat fluxes, which effectively melted the ice and sustained open water conditions in the middle of the Arctic winter. Between March and early July 2013, a persistent ice cover‐modulated air‐sea fluxes. Melting sea ice at the start of the winter initiates a cold, up to 100‐m‐deep halocline separating the ice cover from the warm Atlantic Water. Semidiurnal tides dominate the energy over the upper part of the slope. The vertical tidal structure depends on stratification and varies seasonally, with the potential to contribute to vertical fluxes with shear‐driven mixing. Further processes impacting the heat budget include lateral heat loss due to mesoscale eddies, and modest and negligible contributions of Ekman pumping and shelf break upwelling, respectively. The continental slope north of Svalbard is a key example regarding the role of ocean heat for the sea ice cover. Our study underlines the complexity of the ocean's heat budget that is sensitive to the balance between oceanic heat advection, vertical fluxes, air‐sea interaction, and the sea ice cover.
North Atlantic Ocean Internal Decadal Variability: Role of the Mean State and Ocean‐Atmosphere Coupling
Authors: Gastineau Guillaume , Mignot Juliette , Arzel Olivier , Huck Thierry
Published: August 2018

The origin of the decadal variability in the North Atlantic Ocean is investigated in a series of coupled and ocean‐only numerical experiments. Two versions of the IPSL‐CM5A model are considered, differing only by their atmospheric horizontal resolution (3.75° × 1.87° and 2.5° × 1.25°). When the ocean model is forced by the climatological surface fluxes from the low atmospheric resolution coupled model version, a 20‐year variability emerges, similar to the variability found in the coupled simulation. Such decadal variability is consistent with a large‐scale baroclinic instability of the mean flow in the west European basin. Increasing the atmospheric resolution leads to a more intense Icelandic low, which intensifies the western subpolar gyre, and warms the eastern North Atlantic subpolar gyre region. The mean state changes nearly vanish the associated internal oceanic variability under the corresponding climatological surface fluxes. Increasing the atmospheric resolution also produces a slightly weaker atmospheric stochastic forcing. Both the mean state and atmospheric variability changes are consistent with the decreasing amplitude of the variability in the coupled model. For both model versions, the amplitude of the internal oceanic variability is strongly enhanced in the presence of atmospheric stochastic forcing. Air‐sea coupling on the other hand has a moderate influence on the amplitude of the variability only in the low‐resolution model version, where the North Atlantic oceanic variability at 20 years increases by 23% due to coupling. The coupling effect is therefore modest and sensitive to the atmospheric horizontal resolution.
Assessment of Regional Mercury Deposition and Emission Outflow in Mainland China
Authors: Wang Xun , Lin Che‐Jen , Feng Xinbin , Yuan Wei , Fu Xuewu , Zhang Hui , Wu Qingru , Wang Shuxiao
Published: August 2018

Mainland China is the largest emission region of anthropogenic mercury (Hg) in the world. There have been concerns regarding the emission outflow and chemical transport budget of Hg in the region. Earlier assessments of Hg chemical transport were based on relatively outdated emission data. Recent estimates for anthropogenic (Wu et al., 2016, https://doi.org/10.1021/acs.est.6b04308) and natural Hg emissions (X. Wang, Lin, et al., 2016, https://doi.org/10.5194/acp‐16‐11125‐2016) show substantial differences from earlier emission inventories. In this study, we applied the updated Hg emission estimates to reassess the regional transport budget using Community Multiscale Air Quality‐Hg v5.1. Our results show that the variation of simulated concentration, deposition, and associated emission outflow of Hg are primarily influenced by the spatial‐temporal variation of Hg emissions, monsoon shifts, and particulate matter pollution in China. Total Hg deposition in Mainland China is estimated to be 422 Mg/year, and approximately two thirds of the deposition is contributed by domestic emissions. The net Hg transport budget from Mainland China is 511 Mg/year, contributing to 10% of Hg deposition in other regions of the world. This reassessment points to a ~25% reduction in total annual outflow compared to the previous estimate by Lin et al. (2010, https://doi.org/10.5194/acp‐10‐1853‐2010). Such reduction is mainly caused by changes in Hg emission quantity, speciation, and spatial/temporal distributions. More modeling studies focusing on reducing uncertainties of emission inventories and Hg atmospheric chemistry are needed for continuous assessment of Hg emission outflow in this emission‐intensive region.
An Estimate of Equilibrium Climate Sensitivity From Interannual Variability
Authors: Dessler A. E. , Forster P. M.
Published: August 2018

Estimating the equilibrium climate sensitivity (ECS; the equilibrium warming in response to a doubling of CO2) from observations is one of the big problems in climate science. Using observations of interannual climate variations covering the period 2000 to 2017 and a model‐derived relationship between interannual variations and forced climate change, we estimate that ECS is likely 2.4–4.6 K (17–83% confidence interval), with a mode and median value of 2.9 and 3.3 K, respectively. This analysis provides no support for low values of ECS (below 2 K) suggested by other analyses. The main uncertainty in our estimate is not observational uncertainty but rather uncertainty in converting observations of short term, mainly unforced climate variability to an estimate of the response of the climate system to long‐term forced warming.
Rossby Wave Breaking and Isentropic Stratosphere‐Troposphere Exchange During 1981–2015 in the Northern Hemisphere
Authors: Jing P. , Banerjee S.
Published: August 2018

To better understand the potential effects of climate change on atmospheric dynamics, this paper studies Rossby wave breaking and isentropic stratosphere‐troposphere exchange (STE) in the Northern Hemisphere between 320 and 380 K during 1981–2015 using the Modern‐Era Retrospective Analysis for Research and Application version 2 data. The isentropic STE is estimated using Contour Advection. Our results show that anticyclonic wave breaking events have become more frequent, especially in summer at higher isentropic surfaces, and cyclonic wave breaking events have become less frequent at 320 K. The anticyclonic wave breaking has shifted poleward in summer. The isentropic STE is found to be strongest over the regions where Rossby wave breaking activities are most frequent. Both isentropic STE and Rossby wave breaking are shown to be strongest in summer and weakest in winter. Our results do not show any discernable trends during isentropic STE during 1981–2015.
Whole-genome analysis for effective clinical diagnosis and gene discovery in early infantile epileptic encephalopathy
Authors: Ostrander Betsy E. P. , Butterfield Russell J. , Pedersen Brent S. , Farrell Andrew J. , Layer Ryan M. , Ward Alistair , Miller Chase , DiSera Tonya , Filloux Francis M. , Candee Meghan S. , Newcomb Tara , Bonkowsky Joshua L. , Marth Gabor T. , Quinlan Aaron R.
Published: August 2018

Early infantile epileptic encephalopathy (EIEE) is a devastating epilepsy syndrome with onset in the first months of life. Although mutations in more than 50 different genes are known to cause EIEE, current diagnostic yields with gene panel tests or whole-exome sequencing are below 60%. We applied whole-genome analysis (WGA) consisting of whole-genome sequencing and comprehensive variant discovery approaches to a cohort of 14 EIEE subjects for whom prior genetic tests had not yielded a diagnosis. We identified both de novo point and INDEL mutations and de novo structural rearrangements in known EIEE genes, as well as mutations in genes not previously associated with EIEE. The detection of a pathogenic or likely pathogenic mutation in all 14 subjects demonstrates the utility of WGA to reduce the time and costs of clinical diagnosis of EIEE. While exome sequencing may have detected 12 of the 14 causal mutations, 3 of the 12 patients received non-diagnostic exome panel tests prior to genome sequencing. Thus, given the continued decline of sequencing costs, our results support the use of WGA with comprehensive variant discovery as an efficient strategy for the clinical diagnosis of EIEE and other genetic conditions.
Identification and functional study of a mild allele of SlDELLA gene conferring the potential for improved yield in tomato
Authors: Shinozaki Yoshihito , Ezura Kentaro , Hu Jianhong , Okabe Yoshihiro , Bénard Camille , Prodhomme Duyen , Gibon Yves , Sun Tai-ping , Ezura Hiroshi , Ariizumi Tohru
Published: August 2018

Parthenocarpy, or pollination-independent fruit set, is an attractive trait for fruit production and can be induced by increased responses to the phytohormone gibberellin (GA), which regulates diverse aspects of plant development. GA signaling in plants is negatively regulated by DELLA proteins. A loss-of-function mutant of tomatoDELLA(SlDELLA),procera(pro) thus exhibits enhanced GA-response phenotypes including parthenocarpy, although thepromutation also confers some disadvantages for practical breeding. This study identified a new milder hypomorphic allele ofSlDELLA,procera-2(pro-2), which showed weaker GA-response phenotypes thanpro. Thepro-2mutant contains a single nucleotide substitution, corresponding to a single amino acid substitution in the SAW subdomain of the SlDELLA. Accumulation of the mutatedSlDELLAtranscripts in wild-type (WT) resulted in parthenocarpy, while introduction of intactSlDELLAintopro-2rescued mutant phenotypes. Yeast two-hybrid assays revealed that SlDELLA interacted with three tomato homologues of GID1 GA receptors with increasing affinity upon GA treatment, while their interactions were reduced by theproandpro-2mutations. Bothproandpro-2mutants produced higher fruit yields under high temperature conditions, which were resulted from higher fruit set efficiency, demonstrating the potential for genetic parthenocarpy to improve yield under adverse environmental conditions.
Mutual Interaction between Plasma Characteristics and Liquid Properties in AC-driven Pin-to-Liquid Discharge
Authors: Yoon Sung-Young , Jeon Hyeongwon , Yi Changho , Park Seungil , Ryu Seungmin , Kim Seong Bong
Published: August 2018

This study investigated the mutual interaction between the plasma and plasma treated water (PTW). Many works have shown that the plasma treatment decreases the pH of PTW due to nitric oxide electrolyte ion but the interactions between PTW and the plasma are still largely unknown. We investigated the effect of PTW on a plasma as well as the effect of a plasma on PTW using a pin-to-liquid discharge system. It is found that PTW affects not only the chemical properties but also the physical properties of the plasma such as breakdown voltage and concentration of plasma column. The decrease of the liquid surface tension of PTW due to nitric oxide electrolyte ion from the plasma results in the increase of plasma current onto the surface of PTW and vice versa. The feedback process will be continued until the transition from normal discharge to abnormal discharge. These results can be basic data for the development of plasma sources to treat liquids.
Detection of opsonizing antibodies directed against a recently circulating Bordetella pertussis strain in paired plasma samples from symptomatic and recovered pertussis patients
Authors: Hovingh Elise S. , Kuipers Betsy , Bonačić Marinović Axel A , Jan Hamstra Hendrik , Hijdra Danielle , Mughini Gras Lapo , van Twillert Inonge , Jongerius Ilse , van Els Cecile A. C. M. , Pinelli Elena
Published: August 2018

Correlates of protection (CoPs) against the highly contagious respiratory disease whooping cough, caused by Bordetella pertussis, remain elusive. Characterizing the antibody response to this pathogen is essential towards identifying potential CoPs. Here, we evaluate levels, avidity and functionality of B. pertussis-specific-antibodies from paired plasma samples derived from symptomatic and recovered pertussis patients, as well as controls. Natural infection is expected to induce protective immunity. IgG levels and avidity to nine B. pertussis antigens were determined using a novel multiplex panel. Furthermore, opsonophagocytosis of a B. pertussis clinical isolate by neutrophils was measured. Findings indicate that following infection, B. pertussis-specific antibody levels of (ex-) pertussis patients waned, while the avidity of antibodies directed against the majority of studied antigens increased. Opsonophagocytosis indices decreased upon recovery, but remained higher than controls. Random forest analysis of all the data revealed that 28% of the opsonophagocytosis index variances could be explained by filamentous hemagglutinin- followed by pertussis toxin-specific antibodies. We propose to further explore which other B. pertussis-specific antibodies can better predict opsonophagocytosis. Moreover, other B. pertussis-specific antibody functions as well as the possible integration of these functions in combination with other immune cell properties should be evaluated towards the identification of CoPs against pertussis.
Quinolone-fused cyclic sulfonamide as a novel benign antifilarial agent
Authors: Mukherjee Suprabhat , Joardar Nikhilesh , Mondal Shovan , Schiefer Andrea , Hoerauf Achim , Pfarr Kenneth , Babu Santi P. Sinha
Published: August 2018

Search of potent antifilarial drugs has been a major thrust area in tropical medicine research over the decades. Herein, we report 4,7-dimethyl-3,4,7,8-tetrahydro-3λ6-[1,2]thiazino[4,3-f]quinoline-3,3,8-trione (8l) as a new class of antifilarial agent which is extremely potent, with lethality against all the developmental stages (oocyte, microfilaria and adult) of the filarial parasite Setaria cervi. Molecular investigation on its mode of action revealed that 8l is a typical inducer of reactive oxygen species that triggers oxidative stress inside the filarid and further signals induction of apoptosis by activating both intrinsic and extrinsic pathways. Moreover, 8l is also active against Wolbachia, the essential endosymbiont of several human infectious filarids. Selective toxicity against filarial parasites and non-toxic nature in rat model were found as unique traits of 8l to be a future medicine. Taken en masse, this maiden report on a novel quinolone fused cyclic sulfonamide presents a promising therapeutic lead for lymphatic filariasis in future.
ESIPT-based ratiometric fluorescence probe for the intracellular imaging of peroxynitrite
Authors: Wu Luling , Wang Yang , Weber Maria , Liu Liyuan , Sedgwick Adam C. , Bull Steven D. , Huang Chusen , James Tony D.
Published: August 2018

In this work, we set out to develop an ER directed ESIPT-based ONOO− ratiometric fluorescent probe (ABAH-LW).