bluuebunny/crossref_metadata_2025 huggingface dataset:
Metallated Macrocyclic Derivatives as a Hole – Transporting Materials for Perovskite Solar Cells
Authors: Reddy Govind , Devulapally Koteshwar , Islavath Nanaji , Giribabu Lingamallu
Published: January 2019

Spiro‐OMeTAD is widely used as thehole‐transporting material (HTM) in perovskite solar cells (PSC), which extracts positive charges and protects the perovskite materials from metal electrode, setting a new world‐record efficiency of more than 20 %. Spiro‐OMeTAD layer engross moisture leading to the degradation of perovskite, and therefore, has poor air stability. It is also expensive therefore limiting scale‐up, so macrocyclic metal complex derivatives (MMDs) could be a suitable replacement. Our review covers low‐cost, high yield hydrophobic materials with minimal steps required for synthesis of efficient HTMs for planar/mesostructured PSCs. The MMDs based devices demonstrated PCEs around 19 % and showed stability for a longer duration, indicating that MMDs are a promising alternative to spiro‐OMeTAD and also easy to scale‐up via solution approach. Additionally, this review describes how optical and electrical properties of MMDs change with chemical structure, allowing for the design of novel hole‐mobility materials to achieve negligible hysteresis and act as effective functional barriers against moisture which results in a significant increase in the stability of the device. We provide an overview of the apt green‐synthesis, characterization, stability and implementation of the various classes of macrocyclic metal complex derivatives as HTM for photovoltaic applications.
Multiscale simulation on thermal stability of supported metal nanocatalysts
Authors: Deng Shengwei , Qiu Chenglong , Yao Zihao , Sun Xiang , Wei Zhongzhe , Zhuang Guilin , Zhong Xing , Wang Jian‐guo
Published: January 2019

Supported metal nanocatalysts offer a wide range of promising applications because of their many enhanced catalytic properties arising from highly active species dispersed onto a high surface area support. Developing a deep understanding of thermal stability is of great importance to avoid irreversible catalyst deactivation. It is generally acknowledged that many factors including the chemical composition, morphology, support material, metal–support interaction, reaction condition and environment have significant impacts on the thermal stability. The rapid developments of computational capacity and advanced simulation techniques allow one to correlate the structure–property relationships at the atomic level. In this review, the widely used simulation methods and computational strategies on supported metal nanocatalysts will be briefly introduced. Next, we will summarize the theoretical models of structure evolution of nanoparticles and describe the calculation of metal–support interaction, accompanying with intra‐ and inter‐particle sintering process in the vacuum or reaction environments, and then give perspectives on the future directions towards better utilization of various simulation techniques.

This article is categorized under:

Structure and Mechanism > Reaction Mechanisms and Catalysis

Structure and Mechanism > Computational Materials Science
Turbulence and interphase mass diffusion assumptions on the performance of secondary settling tanks
Authors: Gao Haiwen , Stenstrom Michael K.
Published: January 2019

Secondary settling tanks (SSTs), also known as secondary sedimentation tanks or secondary clarifiers, are a basic yet complicated process in a biological water resource recovery facility. In order to understand and improve SST performance, computational fluid dynamics methods have been employed over the last 30 years. In the present investigation, a Fluent‐based two‐dimensional axisymmetric numerical model is applied to understand the effects of the buoyancy term (Gb) in the turbulent kinetic energy (TKE) equation and two model parameters (the coefficient of buoyancy term (C3) in the turbulent dissipation rate equation and the turbulent Schmidt number (σc) in the sludge transport equation) on the performance of an SST. The results show that the hydrodynamics can only be correctly predicted by buoyancy‐coupled TKE equation, unless the mixed liquor suspended solids is low and sludge settling velocity is extremely high. When the field observations show the SST is operating well, the buoyancy‐decoupled TKE equation predicts the correct result, but the buoyancy‐decoupled TKE equation may predict failure. Care is required in selecting the correct modeling technique for various conditions. This study provides guidance on how to avoid modeling problems and increase rates of convergence.

Practitioner points

C3 can be set to zero to improve rate of convergence and reduce computing time.

σc can be used to adjust SBH, when ESS and RAS concentrations are well calibrated to the field data, but the SBH does not fit field observation.
A data mining application in credit scoring processes of small and medium enterprises commercial corporate customers
Authors: Gulsoy Nihan , Kulluk Sinem
Published: January 2019

The constant need to assess loans makes risk evaluation a very important problem for the banking sector. A crucial function of the banks is to fund households and companies from various industries in the economy. Risk is taken by the banks as soon as a loan is given to an entity. Currently, there are sector‐and‐experience based methods of analysis employed by the banks to estimate the risks to be taken. For the credit process, there exist a large number of studies in the literature on scoring individual clients but there are very few studies on scoring small and medium enterprises (SME) commercial corporate customers. In this study, we propose an objective risk measurement method for the lending process of SME commercial corporate customers and performed classification task of data mining by collecting current customer data on credit evaluation process of a bank. For this purpose, we first create a risk measure by looking into the risks identified for existing customers by the analysts of a bank. These scores are used as target variable in the classification process. Then, we extract rules for estimating these scores using Weka software. We used six different algorithms, and compared results in terms of test accuracy, the number of rules, recall, precision and Kappa statistic. We obtained high accuracy rates on real life data by our approach. As a result, we showed that an objective evaluation strategy is possible to use in the lending process for SME commercial corporate customers in the banking system using data mining.

This article is categorized under:

Application Areas > Business and Industry

Technologies > Classification

Application Areas > Industry Specific Applications
Lithium Ion Motion in Lithium Nitridoborate Chalcogenides Li5(BN2)Ch (Ch = Se, Te)
Authors: Schmidt Robert , Ströbele Markus , Eichele Klaus , Meyer Hans‐Jürgen
Published: January 2019

The compounds Li5(BN2)Se and Li5(BN2)Te were synthesized at 900 °C in a closed system utilizing weld shut niobium ampoules and obtained as white microcrystalline powders. Their crystal structures were solved and refined on the basis of single‐crystal X‐ray diffraction data with the space group I41md [a = 6.3983(4) Å, c = 11.1072(9) Å for Li5(BN2)Se and a = 6.5878(3) Å, c = 11.4382(7) Å for Li5(BN2)Te]. The temperature dependent Li+ motion was investigated by 7Li MAS NMR spectroscopy.
The Sodium (Iso)Cyanurates Nax[H3–xC3N3O3]·yH2O (x = 1–3, y = 0, 1): A Key‐Series for Understanding the Crystal Chemistry of Metal (Iso)Cyanurates
Authors: Gross Peter , Höppe Henning A.
Published: January 2019

The (iso)cyanurates Na[H2C3N3O3]·H2O, Na2[HC3N3O3]·H2O, Na2[HC3N3O3], and Na3[C3N3O3] were synthesized phase pure from Na2CO3·10H2O, NaOH, and cyanuric acid, respectively, in aqueous solution by carefully adjusting the crystallization conditions. The crystal structures of all compounds were determined by single‐crystal X‐ray diffraction {Na2[HC3N3O3]·H2O: P1, a = 3.51660(10) Å, b = 7.8300(3) Å, c = 11.3966(4) Å, α = 86.4400(10)°, β = 85.5350(10)°, γ = 85.0720(10)°, Z = 2, R1 = 0.030, wR2 = 0.078; Na2[HC3N3O3]: Pnma, a = 6.3409(6) Å, b = 12.2382(13) Å, c = 6.5919(7) Å, Z = 4, R1 = 0.045, wR2 = 0.079; Na3[C3N3O3]: R3c, a = 11.7459(3) Å, c = 6.5286(3) Å, Z = 3, R1 = 0.039, wR2 = 0.066}. The structures show ribbons (Na[H2C3N3O3]·H2O), dimers (Na2[HC3N3O3]·H2O), chains (Na2[HC3N3O3]), or columns (Na3[C3N3O3]) of hydrogen‐bonded and parallel stacked (iso)cyanurate anions. These motifs are shown to be characteristic for certain degrees of protonation and hydration, and all (iso)cyanurate crystal structures found so far were classified accordingly. X‐ray powder patterns, thermogravimetry curves, IR and UV/Vis spectra were measured for all compounds.
Maximally $$ \mathcal{N} $$ -extended super-BMS3 algebras and generalized 3D gravity solutions
Authors: Banerjee Nabamita , Bhattacharjee Arindam , Lodato Ivano , Neogi Turmoli
Published: January 2019

Abstract

We consider the maximal

$$ \mathcal{N} $$

N

-extended supergravity theory in 3 dimensions with fermionic generators transforming under real but non necessarily irreducible representations of the internal algebra. We obtain the symmetry algebra at null infinity preserving boundary conditions of asymptotically flat solutions, i.e. the maximal

$$ \mathcal{N} $$

N

-extended super-BMS3 algebra, which possesses non-linear correction in the anti-commutators of supercharges. We present the supersymmetric energy bound and derive the explicit form of the asymptotic Killing spinors. We also find the most generic circular symmetric ground state of the theory, which corresponds to a non-supersymmetric cosmological solutions and derive their entropy.
Upper and lower bounds on the integrated null energy in gravity
Authors: Leichenauer Stefan , Levine Adam
Published: January 2019

Abstract

We prove a lower bound on the integrated null energy along achronal geodesic segments using induced gravity on a brane in AdS/CFT. The bound follows from the assumption that bulk causality respects brane causality, and matches a bound recently conjectured by Freivogel and Krommydas for semiclassical gravity. We also prove a more general upper bound on the same quantity that follows simply from achronality. We check that the lower bound is satisfied in recent constructions of traversable wormholes, and demonstrate that the bound is related to causality in the ambient spacetime of the wormhole.
Shedding light on top partner at the LHC
Authors: Alhazmi Haider , Kim Jeong Han , Kong Kyoungchul , Lewis Ian M.
Published: January 2019

Abstract

We investigate the sensitivity of the 14 TeV LHC to pair-produced top partners (T) decaying into the Standard Model top quark (t) plus either a gluon (g) or a photon (γ). The decays T → tg and T → tγ can be dominant when the mixing between the top partner and top quark are negligible. In this case, the conventional decays T → bW , T → tZ, and T → th are highly suppressed and can be neglected. We take a model-independent approach using effective operators for the T -t-g and T -t-γ interactions, considering both spin-

$$ \frac{1}{2} $$

1
2

and spin-

$$ \frac{3}{2} $$

3
2

top partners. We perform a semi-realistic simulation with boosted top quark tagging and an appropriate implementation of a jet-faking-photon rate. Despite a simple dimensional analysis indicating that the branching ratios BR(T → tγ) ≪ BR(T → tg) due to the electric-magnetic coupling being much smaller than the strong force coupling, our study shows that the LHC sensitivity to

$$ T\overline{T}\to t\overline{t}\gamma g $$

T

T
¯

→
t

t
¯

γ
g

is more significant than the sensitivity to

$$ T\overline{T}\to t\overline{t} gg $$

T

T
¯

→
t

t
¯

gg

. This is due to much smaller backgrounds attributed to the isolated high-p

T
photon. We find that with these decay channels and 3 ab−1 of data, the LHC is sensitive to top partner masses m

T
≲ 1.4-1.8 TeV for spin-

$$ \frac{1}{2} $$

1
2

and spin-

$$ \frac{3}{2} $$

3
2

top partners, respectively.
Searching for a charged Higgs boson with both H±W∓Z and H±tb couplings at the LHC
Authors: Cen Jian-Yong , Chen Jung-Hsin , He Xiao-Gang , Li Gang , Su Jhih-Ying , Wang Wei
Published: January 2019

Abstract

In certain new physics scenarios, a singly charged Higgs boson can couple to both fermions andW±Zat tree level. We develop new strategies beyond current experimental searches usingpp→jjH±,H±→tbat the Large Hadron Collider (LHC). With the effectiveH±W∓ZandH±tbcouplings we perform a model-independent analysis at the collision energy$$ \sqrt{s}=13 $$s=13TeV with the integrated luminosity of 3 ab−1. We derive the discovery prospects and exclusion limits for the charged Higgs boson in the mass range from 200 GeV to 1 TeV. With |FWZ|,|At| ∼ 0.5–1.0 and 300 GeV ≲$$ {m}_{H^{\pm }} $$mH±≲ 400 GeV, we point out that a discovery significance of 5σcan be achieved. The constraints and projected sensitivities are also discussed in a realistic model, i.e., the modified Georgi-Machacek model without custodial symmetry. Our proposed search would provide direct evidence for a charged Higgs bosonH±that couples toW±Zandtb, and has better sensitivity to the couplings ofH±W∓ZandH±tbthan current searches.
Safety and tolerability of moxifloxacin for the treatment of disseminated BCGitis in children
Authors: Alsuhaibani Mohammed , Felimban Ghada , Shoukri Mohamed , Alosaimi Abdullah , Almohaizeie Abdullah , AlHajjar Sami
Published: January 2019

Background and objective:

Disseminated BCGitis is a rare but serious complication of BCG vaccine in patients with underlying primary immunodeficiency. Fluoroquinolone antibiotics containing antimycobacterial regimen have been considered in the treatment of disseminated BCGitis, but there are limited data about the dosing, safety, and tolerability of fluoroquinolone such as moxifloxacin in children. The aim of this study was to report the experience with the dosing, safety, and tolerability of moxi- floxacin in children with disseminated BCGitis.

Method:

This retrospective descriptive study included children who had been diagnosed with disseminated BCGitis and treated with an antimycobacterial regimen including moxifloxacin for more than two weeks from 2007 to 2017 at King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.

Result:

Ten children were included: six (60.0%) were male and four (40.0%) were female. The primary diagnosis for five patients was Mendelian susceptibility to mycobacterial diseases (MSMD), four patients were diagnosed with severe combined immune deficiency (SCID), and the remaining patient had human immunodeficiency virus (HIV) infection. The overall mean duration of moxifloxacin treatment was 10.1 months. Liver toxicity was recorded in three patients. The most common medications used with mox- ifloxacin were ethambutol and clarithromycin. Moxifloxacin serum concentration level was determined in 5 patients. No musculoskeletal side effects were reported while the patient was on moxifloxacin. The treated patients showed a different response to an antimycobacterial regimen including moxifloxacin, with mortality in two patients.

Conclusion:

Our study suggests that moxifloxacin is generally tolerated in children and might be considered in disseminated BCGitis cases. Additionally, paying attention to side effects such as liver toxicity is recommended, particularly with the use of other antimycobacterial antibiotics, which could also be hepatotoxic. A moxifloxacin-containing regimen for disseminated BCGitis showed clinical improvement in some patients in this study, although the majority presented the same clinical condition.
Kscien's list; a new strategy to hoist predatory journals and publishers
Authors: Kakamad Fahmi H. , Mohammed Shvan H. , Najar Kayhan A. , Qadr Goran A. , Ahmed Jaafar O. , Mohammed Karukh K. , Salih Rawezh Q. , Hassan Marwan N. , Mikael Tomas M. , Kakamad Suhaib H. , Baba Hiwa O. , Aziz Masrur S. , Rahim Hawbash M. , Ahmmad Dlshad R. , Hussein Dahat A. , Ali Rebwar A. , Hammood Zuhair D. , Essa Rawand A. , Hassan Hunar Ali
Published: January 2019

ABSTRACT

The trend through which academia finances scientific publication has been changed into open access publishing, the latter is exploited by predatory journals and publishers. The aim of this paper is to review the current situation of predatory publishing and introduce Kscien's list of predatory journals and publishers. Kscien has recruited a special committee consisting of 23 young researchers. They are working unceasingly to keep the list refurbished, expose current tricks invented by the predators and guide authors. The list is designed to be updated daily. Currently, the criteria used to recognize predatory journals and publishers basically depend on the journal's misconduct, fabrication and inadequate peer review. Researches are ongoing to recapitulate more solid criteria with objective evidence to overcome the critics faced by Beall. Kscien's list has been proposed to replace the vanished Beall's list from the interior of the drawn region in fake journals and publishers.

Highlights:
Prospect theory and presidential elections: Two cases from Yugoslavia and Serbia
Authors: Pavlović Dušan
Published: January 2019

Why do presidents in semi-presidential regimes sometimes call early elections? Is the behavior of incumbent presidents different from the behavior of presidential contenders when the former do not need to run for office but face the loss of parliamentary majority in a semi-presidential system? Prospect theory claims that agents make risky choices when facing a loss. Consequently, if incumbent presidents face a loss of majority in the parliament, they will call for early election to try to shore up or salvage the majority. To provide empirical evidence supporting this claim, prospect theory has been applied to the two presidential elections in Yugoslavia and Serbia in which two incumbent presidents, Slobodan Miloševiš (2000) and Boris Tadiš (2012), had lost early presidential elections. The expected contribution of the paper is to deepen our understanding of how semipresidential regimes resolve the problem of temporal rigidity and offer novel empirical data in support of the application of prospect theory in political science.
Risk of influenza infection with low vaccine effectiveness: the role of avoidance behaviour
Authors: Vilches Thomas N. , Jaberi-Douraki Majid , Moghadas Seyed M.
Published: January 2019

Low vaccine-effectiveness has been recognised as a key factor undermining efforts to improve strategies and uptake of seasonal influenza vaccination. Aiming to prevent disease transmission, vaccination may influence the perceived risk-of-infection and, therefore, alter the individual-level behavioural responses, such as the avoidance of contact with infectious cases. We asked how the avoidance behaviour of vaccinated individuals changes disease dynamics, and specifically the epidemic size, in the context of imperfect vaccination. For this purpose, we developed an agent-based simulation model, and parameterised it with published estimates and relevant databases for population demographics and agent characteristics. Encapsulating an age-stratified structure, we evaluated the per-contact risk-of-infection and estimated the epidemic size. Our results show that vaccination could lead to a larger epidemic size if the level of avoidance behaviour in vaccinated individuals reduces below that of susceptible individuals. Furthermore, the risk-of-infection in vaccinated individuals, which follows the pattern of age-dependent frailty index of the population, increases for older age groups, and may reach, or even exceed, the risk-of-infection in susceptible individuals. Our findings indicate that low engagement in avoidance behaviour can potentially offset the benefits of vaccination even for vaccines with high effectiveness. While highlighting the protective effects of vaccination, seasonal influenza immunisation programmes should enhance strategies to promote avoidance behaviour despite being vaccinated.
Modeling the Impact of Zooplankton Diel Vertical Migration on the Carbon Export Flux of the Biological Pump
Authors: Archibald Kevin M. , Siegel David A. , Doney Scott C.
Published: January 2019

One pathway of the biological pump that remains largely unquantified in many export models is the active transport of carbon from the surface ocean to the mesopelagic by zooplankton diel vertical migration (DVM). Here, we develop a simple representation of zooplankton DVM and implement it in a global export model as a thought experiment to illustrate the effects of DVM on carbon export and mesopelagic biogeochemistry. The model is driven by diagnostic satellite measurements of net primary production, algal biomass, and phytoplankton size structure. Due to constraints on available satellite data, the results are restricted to the latitude range from 60°N to 60°S. The modeled global export flux from the base of the euphotic zone was 6.5 PgC/year, which represents a 14% increase over the export flux in model runs without DVM. The mean (± standard deviation, SD) proportional contribution of the DVM‐mediated export flux to total carbon export, averaged over the global domain and the climatological seasonal cycle, was 0.16 ± 0.04 and the proportional contribution of DVM activity to total respiration within the twilight zone was 0.16 ± 0.06. Adding DVM activity to the model also resulted in a deep local maximum in the oxygen utilization profile. The model results were most sensitive to the assumptions for the fraction of individuals participating in DVM, the fraction of fecal pellets produced in the euphotic zone, and the fraction of grazed carbon that is metabolized.
Reply to “Geochemical Characteristics of Anatolian Basalts: Comment on ‘Neogene Uplift and Magmatism of Anatolia: Insights from Drainage Analysis and Basaltic Geochemistry’ by McNab et al.”
Authors: McNab F. , Ball P.W. , Hoggard M. J. , White N. J.
Published: January 2019

Uslular and Gençalioğlu‐Kuşcu (2018) have written a lengthy, and highly critical, comment about McNab et al. (2018, https://doi.org/10.1002/2017GC007251) which states that our data compilation for Neogene (and Quaternary) volcanic rocks from Anatolia is selective, inconsistent, and not fit for purpose. We state for the record that our compilation is not based on analyses from the published GEOROC database. Uslular and Gençalioğlu‐Kuşcu (2018) also state that our subdivision of this database into three broad longitudinal categories is unrealistic since it does not consider the full range of different tectonic units. They conclude that our interpretation of the link between Neogene‐Quaternary volcanism and uplift of Anatolia is erroneous. We refute this rather strongly worded comment by carefully addressing the five substantive issues raised.
Predicting the Impact of Climate Change on Severe Wintertime Particulate Pollution Events in Beijing Using Extreme Value Theory
Authors: Pendergrass D. C. , Shen L. , Jacob D. J. , Mickley L. J.
Published: January 2019

We use extreme value theory to develop point process statistical models relating the probability of extreme winter particulate pollution events in Beijing (“winter haze”) to local meteorological variables. The models are trained with the 2009–2017 record of fine particulate matter concentrations (PM2.5) from the U.S. embassy. We find that 850‐hPa meridional wind velocity (V850) and relative humidity successfully predict the probability for 24‐hr average PM2.5to exceed 300 μg/m3(95th percentile of the frequency distribution) as well as higher thresholds. We apply the point process models to mid‐21st century climate projections from the Coupled Model Intercomparison Project Phase 5 model ensemble under two radiative forcing scenarios (RCP8.5 and RCP4.5). We conclude that 21st century climate change alone is unlikely to increase the frequency of severe PM2.5pollution events (PM2.5 > 300 μg/m3) in Beijing and is more likely to marginally decrease the probability of such events.
Insights on Hydrothermal‐Magmatic Interactions and Eruptive Processes at Poás Volcano (Costa Rica) From High‐Frequency Gas Monitoring and Drone Measurements
Authors: de Moor J. M. , Stix J. , Avard G. , Muller C. , Corrales E. , Diaz J. A. , Alan A. , Brenes J. , Pacheco J. , Aiuppa A. , Fischer T. P.
Published: January 2019

Identification of unambiguous signals of volcanic unrest is crucial in hazard assessment. Processes leading to phreatic and phreatomagmatic eruptions remain poorly understood, inhibiting effective eruption forecasting. Our 5‐year gas record from Poás volcano, combined with geophysical data, reveals systematic behavior associated with hydrothermal‐magmatic eruptions. Three eruptive episodes are covered, each with distinct geochemical and geophysical characteristics. Periods with larger eruptions tend to be associated with stronger excursions in monitoring data, particularly in SO2/CO2 and SO2 flux. The explosive 2017 phreatomagmatic eruption was the largest eruption at Poás since 1953 and was preceded by dramatic changes in gas and geophysical parameters. The use of drones played a crucial role in gas monitoring during this eruptive period. Hydrothermal sealing and volatile accumulation, followed by top‐down reactivation of a shallow previously emplaced magma body upon seal failure, are proposed as important processes leading to and contributing to the explosivity of the 2017 eruption.
On Moisture Flux of the Indian Summer Monsoon: A New Perspective
Authors: Rao Kusuma G. , Reddy N. Narendra
Published: January 2019

Moisture flux is the driver of the Indian summer monsoon on all space‐time scales and its accurate representation in monsoon simulation models is crucial. For the first time, the moisture flux measurements are made over India during the PRWONAM (Prediction of Regional Weather using Observational meso‐Network and Atmospheric Modelling) program. These measurements best represented low wind free convection regime (U10 < 2 m/s). Here we show moisture flux scaled linearly with appropriate near‐surface humidity and temperature differentials. The drag scaled linearly with wind speed unlike the moisture and sensible heat fluxes. The sensible heat flux scaled as “4/3” power of a near‐surface temperature differential consistent with Rao et al. (1996a, https://doi.org/10.1029/96GL02368) and Rao (2004, https://doi.org/10.1023/B:BOUN.0000016495.85528.d7). A striking result is that the moisture flux is a linear function of the sensible heat flux at all wind speeds; while drag does not show any dependence on heat flux.
Estimating River Discharge With Swath Altimetry: A Proof of Concept Using AirSWOT Observations
Authors: Tuozzolo S. , Lind G. , Overstreet B. , Mangano J. , Fonstad M. , Hagemann M. , Frasson R. P. M. , Larnier K. , Garambois P.‐A. , Monnier J. , Durand M.
Published: January 2019

The forthcoming Surface Water and Ocean Topography (SWOT) satellite mission will provide global measurements of the free surface of large rivers, providing new opportunities for remote sensing‐derived estimates of river discharge in gaged and ungaged basins. SWOT discharge algorithms have been developed and benchmarked using synthetic data but remain untested on real‐world swath altimetry observations. We present the first discharge estimates from AirSWOT, a SWOT‐like airborne Ka‐band radar, using 6 days of measurements over a 40‐km segment of the Willamette River in Oregon, USA. The three evaluated discharge algorithms estimated discharge with normalized root‐mean‐square errors of 10–31% when compared with in situ gage data but were sensitive to an initial estimate of mean annual discharge. Our results show that these discharge algorithms provide reliable discharge estimates on remotely sensed data at SWOT‐like spatial scales while highlighting the need for further algorithm sensitivity tests.
Reconnection With Magnetic Flux Pileup at the Interface of Converging Jets at the Magnetopause
Authors: Øieroset M. , Phan T. D. , Drake J. F. , Eastwood J. P. , Fuselier S. A. , Strangeway R. J. , Haggerty C. , Shay M. A. , Oka M. , Wang S. , Chen L.‐J. , Kacem I. , Lavraud B. , Angelopoulos V. , Burch J. L. , Torbert R. B. , Ergun R. E. , Khotyaintsev Y. , Lindqvist P. A. , Gershman D. J. , Giles B. L. , Pollock C. , Moore T. E. , Russell C. T. , Saito Y. , Avanov L. A. , Paterson W.
Published: January 2019

We report Magnetospheric Multiscale observations of reconnection in a thin current sheet at the interface of interlinked flux tubes carried by converging reconnection jets at Earth's magnetopause. The ion skin depth‐scale width of the interface current sheet and the non‐frozen‐in ions indicate that Magnetospheric Multiscale crossed the reconnection layer near the X‐line, through the ion diffusion region. Significant pileup of the reconnecting component of the magnetic field in this and three other events on approach to the interface current sheet was accompanied by an increase in magnetic shear and decrease in Δβ, leading to conditions favorable for reconnection at the interface current sheet. The pileup also led to enhanced available magnetic energy per particle and strong electron heating. The observations shed light on the evolution and energy release in 3‐D systems with multiple reconnection sites.
Warming Trends in Summer Heatwaves
Authors: Chapman S. C. , Watkins N. W. , Stainforth D. A.
Published: January 2019

The frequency and severity of heatwaves is expected to increase as the global climate warms. We apply crossing theory for the first time to determine heatwave properties solely from the distribution of daily observations without time‐correlation information. We use Central England Temperature time series to quantify how the simple increased occurrence of higher temperatures makes heatwaves (consecutive summer days with temperatures exceeding a threshold) more frequent and intense. We find an overall twofold to threefold increase in heatwave activity since the late 1800's. Week‐long heatwaves that on average return every 5 years were typically below ∼28 °C and now typically exceed it. Our analysis takes as inputs average user‐specific heat wave properties. Its output pinpoints the range of temperatures for which changes in the distribution must be well resolved statistically in order to track how these heatwave properties are changing. This provides a quantitative benchmark for models used for the attribution of heat waves.
Crustal Structure in Alaska From Receiver Function Analysis
Authors: Zhang Ying , Li Aibing , Hu Hao
Published: January 2019

New maps of crustal thickness and Vp/Vs in Alaska and western Canada were obtained using P receiver functions recorded at 198 stations from the USArray Transportable Array and the Alaska Regional Network. Our results indicate that topography and Moho depth are correlated as crustal thickness varies from 28 to 43 km across Alaska. A thick crust occurs under the mountains in the south and north with relatively thin crust in central Alaska. The deepest crustal root beneath the Brooks Range may have lost its buoyancy based on Airy isostasy. In addition, a buoyant upper mantle is required to support the high topography in east central Alaska. Vp/Vs is determined between 1.7 and 1.8 beneath most of Alaska except a high average of 1.9 in the south central region. We attribute this high Vp/Vs to the underplating of Yakutat and Pacific oceanic crust.
Machine Learning Can Predict the Timing and Size of Analog Earthquakes
Authors: Corbi F. , Sandri L. , Bedford J. , Funiciello F. , Brizzi S. , Rosenau M. , Lallemand S.
Published: January 2019

Despite the growing spatiotemporal density of geophysical observations at subduction zones, predicting the timing and size of future earthquakes remains a challenge. Here we simulate multiple seismic cycles in a laboratory‐scale subduction zone. The model creates both partial and full margin ruptures, simulating magnitude Mw 6.2–8.3 earthquakes with a coefficient of variation in recurrence intervals of 0.5, similar to real subduction zones. We show that the common procedure of estimating the next earthquake size from slip‐deficit is unreliable. On the contrary, machine learning predicts well the timing and size of laboratory earthquakes by reconstructing and properly interpreting the spatiotemporally complex loading history of the system. These results promise substantial progress in real earthquake forecasting, as they suggest that the complex motion recorded by geodesists at subduction zones might be diagnostic of earthquake imminence.
Six‐Degree‐of‐Freedom Broadband Seismogeodesy by Combining Collocated High‐Rate GNSS, Accelerometers, and Gyroscopes
Authors: Geng Jianghui , Wen Qiang , Chen Qijin , Chang Hua
Published: January 2019

Combining collocated high‐rate Global Navigation Satellite Systems (GNSS) and accelerometers produces broadband seismogeodetic displacements. However, accelerometer data must be heavily downweighted due to their baseline errors originating primarily in instrument rotations, and therefore their contribution to seismogeodetic displacements is seriously underestimated. We further introduced a gyroscope into this classic seismogeodesy to mitigate baseline errors and formulated advanced six‐degree‐of‐freedom (6‐DOF) seismogeodesy without undervaluing accelerometer data. A shake table holding one GNSS antenna, four accelerometers, and one gyroscope was used to simulate waveforms from the 2010 Mw 7.2 El Mayor‐Cucapah earthquake. We found that the displacements derived from the 6‐DOF seismogeodesy were up to 68% more accurate than those from the classic seismogeodesy over 0.04–0.4 Hz. Moreover, broadband rotations containing the permanent components were also generated, which were unachievable by integrating gyroscope data. We believe that the 6‐DOF seismogeodesy is capable of improving both source rupture studies of large earthquakes and high‐rise monitoring under strong seismic waves.
Thermospheric Weather as Observed by Ground‐Based FPIs and Modeled by GITM
Authors: Harding Brian J. , Ridley Aaron J. , Makela Jonathan J.
Published: January 2019

The first long‐term comparison of day‐to‐day variability (i.e., weather) in the thermospheric winds between a first‐principles model and data is presented. The definition of weather adopted here is the difference between daily observations and long‐term averages at the same UT. A year‐long run of the Global Ionosphere Thermosphere Model is evaluated against a nighttime neutral wind data set compiled from six Fabry‐Perot interferometers at middle and low latitudes. First, the temporal persistence of quiet‐time fluctuations above the background climate is evaluated, and the decorrelation time (the time lag at which the autocorrelation function drops to e−1) is found to be in good agreement between the data (1.8 hr) and the model (1.9 hr). Next, comparisons between sites are made to determine the decorrelation distance (the distance at which the cross‐correlation drops to e−1). Larger Fabry‐Perot interferometer networks are needed to conclusively determine the decorrelation distance, but the current data set suggests that it is ∼1,000 km. In the model the decorrelation distance is much larger, indicating that the model results contain too little spatial structure. The measured decorrelation time and distance are useful to tune assimilative models and are notably shorter than the scales expected if tidal forcing were responsible for the variability, suggesting that some other source is dominating the weather. Finally, the model‐data correlation is poor (−0.07 < ρ < 0.36), and the magnitude of the weather is underestimated in the model by 65%.
On the Influence of the Earth's Magnetic Dipole Eccentricity and Magnetospheric Ring Current on the Magnetopause Location
Authors: Machková A. , Němec F. , Němeček Z. , Šafránková J.
Published: January 2019

We investigate the influence of two typically unconsidered parameters—Earth's magnetic dipole eccentricity and ring current—on the location of the magnetopause. Although empirical magnetopause models generally assume the Earth's magnetic field to be axially symmetric, the terrestrial magnetic dipole is shifted by as much as 500 km out of the Earth's center. Additionally, the magnetic field at the magnetopause is further modified by magnetospheric currents, most importantly by the ring current. In order to quantify the effects related to these phenomena on the magnetopause location, we compare observed magnetopause distances with model distances calculated using a model, which does not take them into account. International Geomagnetic Reference Field is used to describe the dipole eccentricity and relevant multipoles, which results in a statistically observable magnetopause displacement (≈0.2RE) at locations where the magnetic field strength increases/decreases as compared to the dipole field. Additionally, the magnetic field at the magnetopause is modified by the ring current, becoming stronger at the times of a stronger ring current. We use the corrected Dst* index to describe the ring current strength, and we demonstrate that its variation results in a change of the magnetopause stand‐off distance as large as about 0.8RE. We further use the T96 magnetic field model to estimate the total contribution of magnetospheric currents to the magnetic field at the magnetopause and their effects on the magnetopause location. We suggest empirical relations that can be used to incorporate the obtained dependences into existing empirical models of magnetopause location.
Long‐Term and Solar Cycle Variation of Galactic Cosmic Rays: Evidence for Variable Heliospheric Turbulence
Authors: Väisänen Pauli , Usoskin Ilya , Mursula Kalevi
Published: January 2019

The Sun modulates the flux of galactic cosmic rays (GCR) reaching the Earth's orbit. GCR flux has been measured by ground‐based neutron monitors (NMs) for several decades, which provides an interesting long‐term monitor of solar activity and the heliospheric magnetic field. Here we study the long‐term evolution of the power spectrum of GCR over the last six solar cycles, using the power law slope in the frequency range 5.56·10−6 to 2.14·10−6 Hz (between 50 and 130 hr). We use data from 31 neutron monitors during 1953–2016. We show that the power law slopes vary within the solar cycle, with a Kolmogorov‐type slope observed at solar minimum and a random‐walk‐type slope observed at solar maximum. This implies that the different conditions in the different phases of the solar cycle affect the scaling properties of heliospheric turbulence and, thereby, cosmic ray variability.
A Revised Look at Relativistic Electrons in the Earth's Inner Radiation Zone and Slot Region
Authors: Claudepierre S. G. , O'Brien T. P. , Looper M. D. , Blake J. B. , Fennell J. F. , Roeder J. L. , Clemmons J. H. , Mazur J. E. , Turner D. L. , Reeves G. D. , Spence H. E.
Published: January 2019

We describe a new, more accurate procedure for estimating and removing inner zone background contamination from Van Allen Probes Magnetic Electron Ion Spectrometer (MagEIS) radiation belt measurements. This new procedure is based on the underlying assumption that the primary source of background contamination in the electron measurements at L shells less than three, energetic inner belt protons, is relatively stable. Since a magnetic spectrometer can readily distinguish between foreground electrons and background signals, we are able to exploit the proton stability to construct a model of the background contamination in each MagEIS detector by only considering times when the measurements are known to be background dominated. We demonstrate, for relativistic electron measurements in the inner zone, that the new technique is a significant improvement upon the routine background corrections that are used in the standard MagEIS data processing, which can “overcorrect” and therefore remove real (but small) electron fluxes. As an example, we show that the previously reported 1‐MeV injection into the inner zone that occurred in June of 2015 was distributed more broadly in L and persisted in the inner zone longer than suggested by previous estimates. Such differences can have important implications for both scientific studies and spacecraft engineering applications that make use of MagEIS electron data in the inner zone at relativistic energies. We compare these new results with prior work and present more recent observations that also show a 1‐MeV electron injection into the inner zone following the September 2017 interplanetary shock passage.
A North‐South Contrast of Subsurface Salinity Anomalies in the Northwestern Pacific From 2002 to 2013
Authors: Yan Youfang , Svendsen Lea , Wang Chunzai , Keenlyside Noel , Xu Dazhi
Published: January 2019

This paper finds a north‐south contrast of subsurface salinity trend during 2002–2013 in the northwestern Pacific. Both Argo float data and long‐term repeat hydrographic measurements along the 137°E section show that salinity anomalies along the isopycnals of 24.5–25.4 kg/m3 exhibit a pronounced decreasing trend north of 15°N and an increasing trend south of 15°N. We perform a quantitative analysis based on satellite‐derived data and a qualitative analysis that used a lower‐order isopyncal salinity model that represents key balance terms (i.e., evaporation E, precipitation P, and wind forcing advection). Both of the analyses consistently show that the subsurface salinity anomalies in the north and south of 15°N are induced by different physical processes. Fresher surface waters in the northwestern subtropical outcrop region due to an excess freshwater supply (E − P < 0) contribute to the freshening of subsurface waters north of 15°N. In contrast, saltier surface waters in the northeastern subtropical subduction region induced by a deficit of freshwater (E − P > 0) and anomalous ocean circulation associated with the recent accelerated trade winds of the tropical Pacific cause the saltiness of subsurface waters south of 15°N. The results imply that the salinity north‐south contrast may play an important role in changing ocean thermocline structure and upper ocean stratification in the northwestern Pacific.
Observed Vertical Structure of Convection During Dry and Wet Summer Monsoon Epochs Over the Western Ghats
Authors: Utsav Bhowmik , Deshpande Sachin M. , Das Subrata K. , Pandithurai Govindan , Niyogi Dev
Published: January 2019

Summer precipitation over the Western Ghats is an important facet of Indian monsoon. The vertical structure of mesoscale convection during dry and wet epochs of regional precipitation is studied using X‐band Doppler radar, for the first time. The observed characteristics are distinctly different in terms of small‐scale convective and large‐scale atmospheric features for the dry versus wet regimes. The depth and intensity of convection is analyzed using various echo‐top heights (ETHs). The frequency distribution of 0‐ and 15‐dBZ ETH exhibits bimodality during the dry period, which changes to unimodal in wet period. Top heights of precipitating convection (characterized by 30‐dBZ echoes) decreased with low‐level static stability, suggesting preponderance of shallow convection with little stratiform clouds. Suppressed heating in the dry period is a signature of reduced 0‐dBZ ETH occurrence. However, its enhanced occurrence during the wet period resulted in cooling below 2 km and increased heating aloft with maxima at 6 km. Near high precipitation events, midtropospheric humidity rapidly builds up over 2–3 days prior to increase in cloud‐top heights and areal coverage. Observations indicate large amplitude of ETH diurnal cycle during the dry period (especially over leeside) accompanied by weak upstream winds. However, during the wet period, smaller amplitude of ETH is evident (throughout the radar domain) under strong upstream wind conditions. Convective activity during the late afternoon hours produces higher lighting flashes in the dry period compared to the wet. The lightning occurrences are related with penetrations of 30‐dBZ ETH above the freezing level and convective area fractions.
Characteristics of Summer Season Raindrop Size Distribution in Three Typical Regions of Western Pacific
Authors: Wu Zuhang , Zhang Yun , Zhang Lifeng , Lei Hengchi , Xie Yanqiong , Wen Long , Yang Jiefan
Published: January 2019

Raindrop size distribution (DSD) measurements were taken with an onboard OTT Particle Size Velocity (Parsivel) disdrometer over the western Pacific during a marine survey from June to July 2014. Three subregions named south western Pacific (SWP), west western Pacific, and north western Pacific were separated for a comparative study of the variability of DSD. In addition to disdrometer data, FengYun‐2E, Moderate Resolution Imaging Spectroradiometer, National Centers for Environmental Prediction Global Final Analysis, and radiosonde data sets are used to illustrate the dynamical and microphysical characteristics associated with summer season rainfall of western Pacific. The DSD characteristics of six different rain rates and two rain types (convective and stratiform) were studied. Histograms of normalized intercept parameter log10(Nw) and mass‐weighted mean diameter Dm indicated largest log10(Nw) values in west western Pacific, while largest Dm values in south western Pacific, and the convective clusters in three regions could be identified between maritime like and continental like. The constrained relations between shape μ and slope Λ, Nw, and Dm of gamma DSDs are derived. An inverse relation of the coefficients and exponents of Z‐ARb for convective rain were found in three regions. The R (ZH, ZDR) estimator is proved to be more accurate than Z‐R relation algorithm. And the empirical relations between Dm and radar reflectivity factor in the Ku and Ka bands are also derived to improve the rainfall retrieval algorithms in the open sea of Pacific. Furthermore, the possible causative mechanisms for the significant DSD variability in three regions were investigated with respect to convective intensity, raindrop evaporation, and other meteorological variables.
Banded Convective Activity Associated With Mesoscale Gravity Waves Over Southern China
Authors: Du Yu , Zhang Fuqing
Published: January 2019

Banded convective activity that occurred near the south coast of China on 30 January 2018 was investigated through convection‐allowing simulations using a nonhydrostatic mesoscale model. The simulations capture reasonably well the observed characteristics of this event. The convective bands are found to be closely related to an episode of mesoscale gravity waves propagating northeastward with a wave speed of around 12 m/s and a primary wavelength of about ~40–50 km. Further analyses and sensitivity experiments reveal that the environment provides a wave duct for these gravity waves, with a thick low‐level stable layer below 850 hPa capped by a low‐stability reflecting layer with a critical level. The strength and depth of the low‐level stable layer determine the intrinsic phase speed and wavelength of the ducted gravity waves. In the sensitivity tests that the stable layer depth is reduced, the wave characteristics change according to what are predicted with the wave duct theory. The convective bands collocate and propagate in phase with the peak updraft regions of the gravity waves, suggesting strong interactions of convection and gravity waves, in which the ducted gravity waves can trigger and modulate convection, while latent heating from convection enhances the waves. In essence, both wave ducting and wave‐convection interaction are jointly responsible for the banded convective activity.