bluuebunny/crossref_metadata_2025 huggingface dataset:
The radiative transfer model for the greenhouse effect
Authors: Bardos Claude , Pironneau Olivier
Published: August 2021

Radiative transfer is at the heart of the mechanism to explain the greenhouse effect based on the partial infrared opacity of carbon dioxide, methane and other greenhouse gases in the atmosphere. In absence of thermal diffusion, the mathematical model consists of a first order integro-differential equation coupled with an integral equation for the light intensity and the temperature, in the atmosphere. We revisit this much studied system from a mathematical and numerical point of view. Existence and uniqueness and implicit solutions of the Milne problem for grey atmospheres are stated. Numerical simulations are given for grey and non-grey atmospheres and applied to calculate the effect of greenhouse gases. In the context of a transparent atmosphere for sunlight, it is found that by doubling the absorption coefficient in the infrared absorption range of $$\texttt {CO}_2$$

CO
2

the temperature decreases by 2%. On the other hand, the same changes but in the low infrared range of the sunlight leads to an increase of temperature in the atmosphere. Several computer codes were written to cross-validate the results. The authors conclude that the radiative transfer model without thermal diffusion for an atmosphere transparent to the incident sunlight is not capable of explaining the greenhouse effect due to the greenhouse gases. A decreasing temperature due to an increasing proportion of $$\texttt {CO}_2$$

CO
2

has been observed in the high atmosphere (D.W.J. Thomson et al, nature11579). In the lower atmosphere thermal diffusion and convection cannot be neglected and since the absorption coefficient are highly dependent on the temperature, a full ocean–atmosphere–biosphere climate model is required. Hence, driving conclusions from this study on climate change should be cautiously avoided and a review of the hypothesis of the radiative transfer argument commonly found in textbooks should be revisited.
Afriat and arbitrage
Authors: Beggs Alan
Published: August 2021

This paper presents a proof of Afriat’s (Int Econ Rev 8:67–77) theorem on revealed preference by using the idea that a rational consumer should not be vulnerable to arbitrage. The main mathematical tool is the separating hyperplane theorem.
Insights from principal component analysis applied to Py-GCMS study of Indian coals and their solvent extracted clean coal products
Authors: Roy Abyansh , Dhawan Heena , Upadhyayula Sreedevi , Kodamana Hariprasad
Published: August 2021

The present work aims at studying five Indian coals and their solvent extracted clean coal products using Py-GCMS analysis and correlating the characterization data using theoretical principal component analysis. The pyrolysis products of the original coals and the super clean coals were classified as mono-, di- and tri-aromatics, while other prominent products that were obtained included cycloalkanes, n-alkanes, and alkenes ranging from C10–C29. The principal component analysis is a dimensionality reduction technique that reduced the number of input variables in the characterization dataset and gave inferences on the relative composition of constituent compounds and functional groups and structural insights based on scores and loading plots which were consistent with the experimental observations. ATR-FTIR studies confirmed the reduced concentration of ash in the super clean coals and the presence of aromatics. The Py-GCMS data and the ATR-FTIR spectra led to the conclusion that the super clean coals behaved similarly for both coking and non-coking coals with high aromatic concentrations as compared to the raw coal. Neyveli lignite super clean coal was found to show some structural similarity with the original coals, whereas the other super clean coals showed structural similarity within themselves but not with their original coal samples confirming the selective action of the e,N solvent in solubilizing the polycondensed aromatic structures in the coal samples.
Comparative Evaluation of Marking Methods on Cast Parts of Al–Si Alloy with Image Processing
Authors: Deng Fangtian , Li Rui , Klan Steffen , Volk Wolfram
Published: August 2021

Quality issues caused by casting defects are commonly complicated to solve, because the part-specific process parameters are not traced to the individual cast part. This problem can be mitigated by the traceability of each cast part with an identifier code. Therefore, a study of the influence of marked surface topography and post-treatments on code symbol quality is desirable for a well-designed traceability system. In this work, the code symbol quality of laser, dot peen, and electrolytic marking methods on three as-cast surfaces of Al–Si alloy, after sandblasting and heat treatment, is evaluated comparatively with a customized image processing software. The result shows that the laser marking method produces the highest performance for different as-cast surfaces; electrolytic marking provides acceptable results only on the smooth surfaces of high-pressure die casting; dot peen marking produces the codes of high symbol contrasts, which are similar to those of laser marking, especially for rough as-cast surfaces of sand casting. However, for all marking methods, the code qualities of all surface topographies decrease substantially after post-treatments. Considering that dot peen marking has satisfying performances as well as low equipment and maintenance costs, this method is more suitable for small- and medium-size foundries to start to trace each cast part in an economical manner.
FEM Simulations for the Optimization of the Inlet Gate System in Rapid Investment Casting Process for the Realization of Heat Exchangers
Authors: Almonti D. , Baiocco G. , Mingione E. , Ucciardello N.
Published: August 2021

Over the last decades, additive manufacturing (AM) has become the principal production technology for prototypes and components with high added value. In the production of metallic parts, AM allows producing complex geometry with a single process. Also, AM admits a joining of elements that could not be realized with traditional methods. In addition, AM allows the manufacturing of components that could not be realized using other types of processes like reticular structures in heat exchangers. A solid mold investment casting that uses printed patterns overcomes typical limitations of additive processes such as expensive machinery and challenging process parameter settings. Indeed, rapid investment casting provides for a foundry epoxy pattern reproducing the component to exploit in the lost wax casting process. In this paper, aluminium radiators with flat heat pipes seamlessly connected with a cellular structure were conceived and produced. This paper aims at defining and investigating the principal foundry parameters to achieve a defect-free heat exchanger. For this purpose, different device CAD models were designed, considering four pipes’ thickness and length. Finite element method numerical simulations were performed to optimize the design of the casting process. Three different gate configurations were investigated for each length. The numerical investigations led to the definition of a castability range depending on flat heat pipes geometry and casting parameters. The optimal gate configuration was applied in the realization of AM patterns and casting processes
Set-Based Adaptive Distributed Differential Evolution for Anonymity-Driven Database Fragmentation
Authors: Ge Yong-Feng , Cao Jinli , Wang Hua , Chen Zhenxiang , Zhang Yanchun
Published: August 2021

By breaking sensitive associations between attributes, database fragmentation can protect the privacy of outsourced data storage. Database fragmentation algorithms need prior knowledge of sensitive associations in the tackled database and set it as the optimization objective. Thus, the effectiveness of these algorithms is limited by prior knowledge. Inspired by the anonymity degree measurement in anonymity techniques such as k-anonymity, an anonymity-driven database fragmentation problem is defined in this paper. For this problem, a set-based adaptive distributed differential evolution (S-ADDE) algorithm is proposed. S-ADDE adopts an island model to maintain population diversity. Two set-based operators, i.e., set-based mutation and set-based crossover, are designed in which the continuous domain in the traditional differential evolution is transferred to the discrete domain in the anonymity-driven database fragmentation problem. Moreover, in the set-based mutation operator, each individual’s mutation strategy is adaptively selected according to the performance. The experimental results demonstrate that the proposed S-ADDE is significantly better than the compared approaches. The effectiveness of the proposed operators is verified.
BC tree-based spectral sampling for big complex network visualization
Authors: Hu Jingming , Chu Tuan Tran , Hong Seok-Hee , Chen Jialu , Meidiana Amyra , Torkel Marnijati , Eades Peter , Ma Kwan-Liu
Published: August 2021

Graph sampling methods have been used to reduce the size and complexity of big complex networks for graph mining and visualization. However, existing graph sampling methods often fail to preserve the connectivity and important structures of the original graph. This paper introduces a new divide and conquer approach to spectral graph sampling based on graph connectivity, called the BC Tree (i.e., decomposition of a connected graph into biconnected components) and spectral sparsification. Specifically, we present two methods, spectral vertex sampling$$BC\_SV$$BC_SVand spectral edge sampling$$BC\_SS$$BC_SSby computing effective resistance values of vertices and edges for each connected component. Furthermore, we present$$DBC\_SS$$DBC_SSand$$DBC\_GD$$DBC_GD, graph connectivity-based distributed algorithms for spectral sparsification and graph drawing respectively, aiming to further improve the runtime efficiency of spectral sparsification and graph drawing by integrating connectivity-based graph decomposition and distributed computing. Experimental results demonstrate that$$BC\_SV$$BC_SVand$$BC\_SS$$BC_SSare significantly faster than previous spectral graph sampling methods while preserving the same sampling quality.$$DBC\_SS$$DBC_SSand$$DBC\_GD$$DBC_GDobtain further significant runtime improvement over sequential approaches, and$$DBC\_GD$$DBC_GDfurther achieves significant improvements in quality metrics over sequential graph drawing layouts.
Delay in payment effects on productivity of small and medium construction companies in Oman: exploration and ranking
Authors: Al Alawi Mubarak
Published: August 2021

Maintaining a stable productivity rate in a construction project is a challenge. Many external and internal factors influence it. Delay in payment is one of the factors representing the project cash flow and mirrors the company’s financial stability status. This study explores the delay in payments effects on the construction productivity of the small and medium construction companies in Oman. Also, it ranks the delay in payment among other productivity factors. Sixty-five small and medium construction companies registered in Oman Tender Board participated in the questionnaire survey. The results showed that delay in payment significantly affects the financial stability of the companies. The delay in payment was ranked third out of 21 influencing productivity factors. The results were compared with a previous study that covered large construction companies in Oman. It was found that the rank of delay in payment in the small and medium construction is significantly higher than what was found in large companies.
Irreversible phase field models for crack growth in industrial applications: thermal stress, viscoelasticity, hydrogen embrittlement
Authors: Kimura Masato , Takaishi Takeshi , Alfat Sayahdin , Nakano Takumi , Tanaka Yoshimi
Published: August 2021

Three new industrial applications of irreversible phase field models for crack growth are presented in this study. The phase field model for irreversible crack growth in an elastic material is derived as a unidirectional gradient flow of the Francfort–Marigo energy with the Ambrosio–Tortorelli regularization, which is known to be consistent with classic Griffith fracture theory. The obtained compact parabolic-elliptic system of PDEs including two regularization parameters for space and time enables us to simulate various kinds of crack behaviors with standard finite element software, without any geometric restriction on the crack path. We extend the irreversible phase field model to thermal cracking in solder and to cracking in a viscoelastic material, keeping the compact forms of the PDEs and the energy consistency. On the other hand, for hydrogen-assisted cracking in metal, we propose a compact phase field model focusing on a kinematic jamming effect of the hydrogen by a weak coupling approach. Several numerical experiments for these three models show not only their reasonableness and usefulness but also flexible extendability of the phase field approach in fracture mechanics.
Design and exploration of neural network microsystem based on SiP
Authors: Lv Hao , Zhang Shengbing , Deng Bao , Wang Jia , Jing Desheng , Chu Yaoqin , Zhang Kun
Published: August 2021

In recent years, microelectronics technology has entered the era of nanoelectronics/integrated microsystems. System in package (SiP) and system on chip (SoC) are two important technical approaches for the realization of microsystems. Deep learning technology based on neural networks is used in graphics and images. Computer vision and target recognition are widely used. The deep learning technology of convolutional neural network is an important research field in the miniaturization and miniaturization of embedded platforms. How to combine the lightweight neural network with the microsystem to achieve the optimal balance of performance, size, and power consumption is a difficult point. This article introduces a micro-system implementation scheme that combines SiP technology and FPGA-based convolutional neural network. It uses Zynq SoC and FLASH and DDR3 memory as the main components, and uses SiP high-density system packaging technology to integrate. PL end (FPGA) design Convolutional Neural Network, convolutional neural network accelerator, adopt the method of convolution multi-dimensional division and cyclic block to design the accelerator structure, design multiple multiplication and addition parallel computing units to provide the computing power of the system. Improving and accelerating perform on the YOLOv2_Tiny model. The test uses the COCO data set as the training and test samples. The microsystem can accurately identify the target. The volume is only 30 × 30 × 1.2 mm. The performance reaches 22.09GOPs and the power consumption is only 0.81 W under the working frequency of 150 MHz. Multi-objective balance (performance, size and power consumption) of lightweight neural network Microsystems has realized.
Changes in Heme Levels During Acute Vaso-occlusive Crisis in Sickle Cell Anemia
Authors: Cardoso Evilazio Cunha , Silva-Neto Pedro Vieira , Hounkpe Bidossessi Wilfried , Chenou Francine , Albuquerque Cintia Cristina Mateus Xerez , Garcia Nadja Pinto , Silva-Junior Alexander Leonardo , Malheiro Adriana , Cesar Purim , de Lima Franciele , De Paula Erich V. , Fraiji Nelson Abrahim
Published: August 2021

Objective/Background:

Sickle cell anemia (SCA) is associated with increased levels of extracellular heme, which is a key mediator of inflammation in this condition. Despite abundant evidence supporting this concept in cell and animal models, few studies addressed the association between heme levels and the development and severity of acute vasoocclusive crises (VOC) in humans.

Methods:

A cross-sectional study was conducted in patients with acute VOC. Total extracellular heme levels were measured in both plasma and serum at admission and after convalescence, and correlated with other clinical and laboratory markers of SCA severity.

Results:

A total of 28 episodes of VOC in 25 patients were included. Heme levels were similar between admission and convalescence, and correlated with the difference between pre and post hemoglobin, and SCA severity estimated by a composite score of clinical and laboratory markers. Heme levels were neither associated with VOC severity nor with markers of hemostasis activation, and were similar to those reported in an independent population of SCA patients at steady state.

Discussion:

Acute VOC are not characterized by significant increases in total extracellular heme levels. Studies measuring the fraction of free extracellular heme unbound to proteins are warranted to further refine our understanding of the role of heme in acute VOC.
Comprehensive analysis of the association of seasonal variability with maternal and neonatal nutrition in lowland Nepal
Authors: Saville Naomi M , Cortina-Borja Mario , De Stavola Bianca L , Pomeroy Emma , Marphatia Akanksha , Reid Alice , Manandhar Dharma S , Wells Jonathan CK
Published: August 2021

Objective:

To provide a comprehensive seasonal analysis of pregnant mothers’ eating behaviour and maternal/newborn nutritional status in an undernourished population from lowland rural Nepal, where weather patterns, agricultural labour, food availability and disease prevalence vary seasonally.

Design:

Secondary analysis of cluster-randomised Low Birth Weight South Asia Trial data, applying cosinor analysis to predict seasonal patterns.

Outcomes:

Maternal mid-upper arm circumference (MUAC), BMI, dietary diversity, meals per day, eating down and food aversion in pregnancy (≥31 weeks’ gestation) and neonatal z-scores of length-for-age (LAZ), weight-for-age (WAZ) and head circumference-for-age (HCAZ) and weight-for-length (WLZ).

Setting:

Rural areas of Dhanusha and Mahottari districts in plains of Nepal.

Participants:

2831 mothers aged 13–50 and 3330 neonates.

Results:

We found seasonal patterns in newborn anthropometry and pregnant mothers’ anthropometry, meal frequency, dietary diversity, food aversion and eating down. Seasonality in intake varied by food group. Offspring anthropometry broadly tracked mothers’. Annual amplitudes in mothers’ MUAC and BMI were 0·27 kg/m2 and 0·22 cm, with peaks post-harvest and nadirs in October when food insecurity peaked. Annual LAZ, WAZ and WLZ amplitudes were 0·125, 0·159 and 0·411 z-scores, respectively. Neonates were the shortest but least thin (higher WLZ) in winter (December/January). In the hot season, WLZ was the lowest (May/June) while LAZ was the highest (March and August). HCAZ did not vary significantly. Food aversion and eating down peaked pre-monsoon (April/May).

Conclusions:

Our analyses revealed complex seasonal patterns in maternal nutrition and neonatal size. Seasonality should be accounted for when designing and evaluating public heath nutrition interventions.
Magnetic Field and Energetic Particle Flux Oscillations and High‐Frequency Waves Deep in the Inner Magnetosphere During Substorm Dipolarization: ERG Observations
Authors: Miyashita Yukinaga , Chang Tzu‐Fang , Miyoshi Yoshizumi , Hori Tomoaki , Kadokura Akira , Kasahara Satoshi , Wang Shiang‐Yu , Keika Kunihiro , Matsuoka Ayako , Tanaka Yoshimasa , Kasahara Yoshiya , Teramoto Mariko , Jun Chae‐Woo , Asamura Kazushi , Kazama Yoichi , Tam Sunny W. Y. , Wang Bo‐Jhou , Yokota Shoichiro , Kumamoto Atsushi , Tsuchiya Fuminori , Shoji Masafumi , Kurita Satoshi , Imajo Shun , Shinohara Iku
Published: August 2021

Using Exploration of energization and Radiation in Geospace (ERG or Arase) spacecraft data, we studied low‐frequency magnetic field and energetic particle flux oscillations and high‐frequency waves deep in the inner magnetosphere at a radial distance of ~4–5 during substorm dipolarization. The magnetic field oscillated alternately between dipole‐like and taillike configuration at a period of 1 min during dipolarization. When the magnetic field was dipole‐like, the parallel magnetic component of the Pi2 waves was at trough. Both energetic ion and electron fluxes with a few to tens of kiloelectronvolts enhanced out of phase, indicating that magnetosonic waves were in slow mode. Field‐aligned currents also oscillated. These observations are consistent with signatures of ballooning instability. In addition, we found that broadband waves from the Pi1 range to above the electron cyclotron frequency tended to appear intermittently in the central plasma sheet near dipole‐like configuration.
The Winter Heat Budget of Sea Ice in Kotzebue Sound: Residual Ocean Heat and the Seasonal Roles of River Outflow
Authors: Witte Carson R. , Zappa Christopher J. , Mahoney Andrew R. , Goodwin John , Harris Cyrus , Schaeffer Robert J. , Schaeffer Roswell , Betcher Sarah , Hauser Donna D. W. , Laxague Nathan J. M. , Lindsay Jessica M. , Subramaniam Ajit , Turner Kate E. , Whiting Alex
Published: August 2021

The winters of 2017/18 and 2018/19 saw unprecedented sea ice minima in the Bering and Chukchi Seas. Kotzebue Sound, located in the southeastern corner of the Chukchi Sea, remained largely ice‐free throughout the winter in a stark departure from both recorded history and Indigenous oral history. The only sea ice that persisted throughout the winter was landfast ice and most of this occupied a small corner of the Sound near the outflow of the Noatak and Kobuk Rivers. We present oceanographic and atmospheric time series from a heavily instrumented “ice‐tethered observatory” located on this landfast ice above the river outflow channel. This observing station was deployed as part of the Ikaaġvik Sikukun (Iñupiaq for “Ice Bridges”) project, in which hypotheses and subsequent observational programs were co‐produced in partnership with an Indigenous Elder Advisory Council in Kotzebue. The measurements allow us to quantify the heat budget of the ice above the outflow channel, and identify the ocean as the primary source of heat contributing to thinning of the ice, which began in early February and accelerated rapidly before the recovery of the station in April of 2019. In concert with the ice‐tethered observations, we use 2 years of oceanographic measurements from the mouth of Kotzebue Sound to characterize the influence of river outflow on the heat budget of the landfast ice, revealing a seasonal pattern in which the rivers promote ice formation and growth in the fall/winter, but help to drive melting of the ice in spring and early summer.
The Role of Differential Ablation and Dynamic Detachment in Driving Accelerating Mass Loss From a Debris‐Covered Himalayan Glacier
Authors: Rowan Ann V. , Egholm David L. , Quincey Duncan J. , Hubbard Bryn , King Owen , Miles Evan S. , Miles Katie E. , Hornsey Josephine
Published: August 2021

Sustained mass loss from Himalayan glaciers is causing supraglacial debris to expand and thicken, with the expectation that thicker debris will suppress ablation and extend glacier longevity. However, debris‐covered glaciers are losing mass at similar rates to clean‐ice glaciers in High Mountain Asia. This rapid mass loss is attributed to the combined effects of; (a) low or reversed mass balance gradients across debris‐covered glacier tongues, (b) differential ablation processes that locally enhance ablation within the debris‐covered section of the glacier, for example, at ice cliffs and supraglacial ponds, and (c) a decrease in ice flux from the accumulation area in response to climatic warming. Adding meter‐scale spatial variations in supraglacial debris thickness to an ice‐flow model of Khumbu Glacier, Nepal, increased mass loss by 47% relative to simulations assuming a continuous debris layer over a 31‐year period (1984–2015 CE) but overestimated the reduction in ice flux. Therefore, we investigated if simulating the effects of dynamic detachment of the upper active glacier from the debris‐covered tongue would give a better representation of glacier behavior, as suggested by observations of change in glacier dynamics and structure indicating that this process occurred during the last 100 years. Observed glacier change was reproduced more reliably in simulations of the active, rather than entire, glacier extent, indicating that Khumbu Glacier has passed a dynamic tipping point by dynamically detaching from the heavily debris‐covered tongue that contains 20% of the former ice volume.
Geochemical, Biological, and Clumped Isotopologue Evidence for Substantial Microbial Methane Production Under Carbon Limitation in Serpentinites of the Samail Ophiolite, Oman
Authors: Nothaft Daniel B. , Templeton Alexis S. , Rhim Jeemin H. , Wang David T. , Labidi Jabrane , Miller Hannah M. , Boyd Eric S. , Matter Juerg M. , Ono Shuhei , Young Edward D. , Kopf Sebastian H. , Kelemen Peter B. , Conrad Mark E. ,   The Oman Drilling Project Science Team
Published: August 2021

In hyperalkaline () fluids that have participated in low‐temperature (<150) serpentinization reactions, the dominant form of C is often methane (), but the origin of this is uncertain. To assess origin in serpentinite aquifers within the Samail Ophiolite, Oman, we determined fluid chemical compositions, analyzed taxonomic profiles of fluid‐hosted microbial communities, and measured isotopic compositions of hydrocarbon gases. We found that 16S rRNA gene sequences affiliated with methanogens were widespread in the aquifer. We measured clumped isotopologue (D and ) relative abundances less than equilibrium, consistent with substantial microbial production. Furthermore, we observed an inverse relationship between dissolved inorganic C concentrations and across fluids bearing microbiological evidence of methanogenic activity, suggesting that the apparent C isotope effect of microbial methanogenesis is modulated by C availability. An additional source of is evidenced by the presence of ‐bearing fluid inclusions in the Samail Ophiolite and our measurement of high values of ethane and propane, which are similar to those reported in studies of ‐rich inclusions in rocks from the oceanic lithosphere. In addition, we observed 16S rRNA gene sequences affiliated with aerobic methanotrophs and, in lower abundance, anaerobic methanotrophs, indicating that microbial consumption of in the ophiolite may further enrich in 13C. We conclude that substantial microbial is produced under varying degrees of C limitation and mixes with abiotic released from fluid inclusions. This study lends insight into the functioning of microbial ecosystems supported by water/rock reactions.
Reconstructing the Dynamics of the Outer Electron Radiation Belt by Means of the Standard and Ensemble Kalman Filter With the VERB‐3D Code
Authors: Castillo Tibocha Angelica M. , de Wiljes Jana , Shprits Yuri Y. , Aseev Nikita A.
Published: August 2021

Reconstruction and prediction of the state of the near‐Earth space environment is important for anomaly analysis, development of empirical models, and understanding of physical processes. Accurate reanalysis or predictions that account for uncertainties in the associated model and the observations, can be obtained by means of data assimilation. The ensemble Kalman filter (EnKF) is one of the most promising filtering tools for nonlinear and high dimensional systems in the context of terrestrial weather prediction. In this study, we adapt traditional ensemble‐based filtering methods to perform data assimilation in the radiation belts. By performing a fraternal twin experiment, we assess the convergence of the EnKF to the standard Kalman filter (KF). Furthermore, with the split‐operator technique, we develop two new three‐dimensional EnKF approaches for electron phase space density that account for radial and local processes, and allow for reconstruction of the full 3D radiation belt space. The capabilities and properties of the proposed filter approximations are verified using Van Allen Probe and GOES data. Additionally, we validate the two 3D split‐operator Ensemble Kalman filters against the 3D split‐operator KF. We show how the use of the split‐operator technique allows us to include more physical processes in our simulations and is a computationally efficient data assimilation tool that delivers an accurate approximation of the optimal KF solution, and is suitable for real‐time forecasting. Future applications of the EnKF to direct assimilation of fluxes and nonlinear estimation of electron lifetimes are discussed.
Global Hotspots for Future Absolute Temperature Extremes From CMIP6 Models
Authors: Ajjur Salah Basem , Al‐Ghamdi Sami G.
Published: August 2021

Two questions motivated this study: (a) Are global land regions exposed to future changes in absolute temperature extremes? (b) And to which degree? To answer these questions, we projected the trend in four indices, recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI), through the 21st century. Observational (HadEX3) and reanalyses (ERA5, JRA‐55, NCEP‐R‐1, and NCEP‐R‐2) datasets were used to validate and correct the bias in the Coupled Model Intercomparison Project phase 6 (CMIP6) models. CMIP6 models were then used to evaluate the changes globally and in 44 reference regions under two shared socioeconomic pathways (SSPs): SSP2‐4.5 and SSP5‐8.5. Globally, the analysis showed that, under SSP5‐8.5, TXx and TNx would increase by 0.07°C/year, and TXn (TNn) would increase by 0.09 (0.08)°C/year, during the middle of the 21st century (2021–2050), compared with the reference period (1981–2010). These trends are larger during the end of the 21st century (2071–2100). The analysis also showed that all land reference regions are projected to indices growth up to 3.5°C in TXx; 2.8°C in TNx; 4.5°C in TXn; and 4°C in TNn, during the mid‐21st century under SSP5‐8.5. The latter growth in indices increased by 211% for TXx, 237% for TNx, 242% for TXn, and 300% for TNn during the end‐21st century. The global hotspots affected by absolute temperature extremes are in the Northern Hemisphere, including North America, Iceland, Central Asia, Tibetan Plateau, Russian Arctic, Siberia, Mediterranean, Sahara, and Arabian Peninsula. The study's findings help understand the evolution of climate extremes, which is essential for climate change mitigation and adaptation plans.
PBL Height From AIRS, GPS RO, and MERRA‐2 Products in NASA GES DISC and Their 10‐Year Seasonal Mean Intercomparison
Authors: Ding Feng , Iredell Lena , Theobald Michael , Wei Jennifer , Meyer David
Published: August 2021

Within the planetary boundary layer (PBL), surface forcing response, drag, turbulence, and vertical mixing are important processes and play a more critical role here than in the overlying “free atmosphere.” The PBL height (PBLH) is an important parameter in climate models, weather forecasts, and air quality prediction. The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) provides data processing, archiving, and distribution services for numerous Earth science products. PBLH is a parameter in three products served by GES DISC, which are from the atmospheric infrared sounder (AIRS), the global positioning system (GPS) radio occultation (RO) experiment, and the NASA reanalysis product Modern‐Era Retrospective analysis for Research and Applications‐2 (MERRA‐2). These products have different spatial and temporal resolutions and coverages, and their PBLH definitions are also different. To better serve the PBL research community, we have summarized the specifications of these products. A 10‐year seasonal mean intercomparison is also conducted to provide further guidance to users. The intercomparison results show that MERRA‐2 has a much shallower PBL than AIRS and GPS RO. An experimental study indicates that the different PBLH definition in MERRA‐2 caused smaller values of PBLH. The improvement of the water vapor retrieval in AIRS version 7 over version 6 results in the version 7 PBLH agreeing better with GPS RO and MERRA‐2 than version 6, especially near the equator and low latitudes.
Swipe Left on the “Big One”: Better Dates for Cascadia Quakes
Authors: Pearl Jessie , Staisch Lydia
Published: August 2021

Improving our understanding of hazards posed by future large earthquakes on the Cascadia Subduction Zone requires advancements in the methods and sampling used to date and characterize past events.
Lightning Tames Typhoon Intensity Forecasting
Authors: Tripathy-Lang Alka
Published: August 2021

Typhoons regularly drench densely populated western Pacific regions, but lightning could forecast intensity more than a day before a storm’s strength peaks.
Shear‐Wave Velocity Structure of Sediments on Cascadia's Continental Margin From Probabilistic Inversion of Seafloor Compliance Data
Authors: Mosher Stephen G. , Audet Pascal , Gosselin Jeremy M.
Published: August 2021

Several seismic techniques, both passive and active, exist for estimating the shear‐wave velocitystructure of shallow sedimentary structures. In particular, passive compliance signals recorded by broadband ocean‐bottom seismometers (OBSs) can be used to invert forstructure. While compliance‐based imaging studies have been carried out at several locations across the Cascadia Subduction Zone, such an approach has not been extensively applied to OBSs deployed on the continental shelf and slope. In this study, we measure compliance and coherence signals at 13 broadband OBSs deployed along Cascadia's continental shelf and upper slope. We then use a recently developed technique to probabilistically invert compliance signals for shallowstructure that makes use of mixture density neural networks. Finally, we compare and contrast our invertedprofiles and derived properties obtained using this method with previous studies focused on the properties of basin sediments.
Multidisciplinary Constraints on Magma Compressibility, the Pre‐Eruptive Exsolved Volatile Fraction, and the H2O/CO2 Molar Ratio for the 2006 Augustine Eruption, Alaska
Authors: Wasser Valerie K. , Lopez Taryn M. , Anderson Kyle R. , Izbekov Pavel E. , Freymueller Jeffrey T.
Published: August 2021

Geodetically modeled reservoir volume changes during volcanic eruptions are commonly much smaller than the observed eruptive volumes. This discrepancy is thought to be partially due to the compressibility of magma, which is largely controlled by the presence of exsolved volatiles. The 2006 eruption of Augustine Volcano, Alaska, produced an eruptive volume that was ∼3 times larger than the geodetically estimated syn‐eruptive subsurface volume change. In this study, we use a multistep methodology that combines constraints from geodetic, volcanic gas, geologic, and petrologic data together with equations relating physical processes to observable parameters. We apply a Monte Carlo approach to quantify uncertainties. Ultimately, we solve for the exsolved volatile volume fraction and the magma compressibility. We estimate Augustine's 2006 pre‐eruptive exsolved volatile phase to be ∼5.5 vol% of the magma at storage depths, yielding a bulk magma compressibility of ∼3.8 × 10−10 Pa−1. We develop a novel approach to estimate the H2O/CO2 ratio of the syn‐eruptive gas emissions in the absence of direct H2O emission measurements which are hard to obtain due to the high background levels in ambient air. We find a best‐fit H2O/CO2 molar ratio of 29. We also investigate the effects of applying different equations of state to our model. We find that the Ideal Gas Law might be used as a first approximation due to its simplicity; however, it overestimates volatile density and compressibility significantly at storage depths. This project capitalizes on the insights that can be gained by integrating multidisciplinary data with models of physical processes.
Multiscale Geoelectrical Properties of the Rochechouart Impact Structure, France
Authors: Quesnel Yoann , Sailhac Pascal , Lofi Johanna , Lambert Philippe , Rochette Pierre , Uehara Minoru , Camerlynck Christian
Published: August 2021

The 205 Ma Rochechouart impact structure (France) is characterized by various impactite formations overlying the Hercynian crystalline basement. New constraints from downhole logging and surface electrical resistivity measurements along >100 m long profiles reveal that the top melt‐bearing breccia layer is more conductive and porous than the underlying melt‐poor breccia layer. The stratigraphy within the impactite and the transition with the basement are irregular at small (∼1–10 m) and medium (>100 m) scales, with vertical amplitude up to 40–50 m. At larger scale (>1 km), audio‐magnetotelluric observations are able to map the lateral and vertical extent of fracturing/brecciation in the basement, reaching 200 m below the surface nearby Chassenon, in the northern part of the structure. Our results also unveil that the impactite deposits and the brecciated basement of the Rochechouart impact structure may have been shifted laterally and vertically during the modification stage of the impact event through displacements of megablocks, which may be associated with the collapse of a central uplift.
Estimated Mortality and Morbidity Attributable to Smoke Plumes in the United States: Not Just a Western US Problem
Authors: O’Dell Katelyn , Bilsback Kelsey , Ford Bonne , Martenies Sheena E. , Magzamen Sheryl , Fischer Emily V. , Pierce Jeffrey R.
Published: August 2021

As anthropogenic emissions continue to decline and emissions from landscape (wild, prescribed, and agricultural) fires increase across the coming century, the relative importance of landscape‐fire smoke on air quality and health in the United States (US) will increase. Landscape fires are a large source of fine particulate matter (PM2.5), which has known negative impacts on human health. The seasonal and spatial distribution, particle composition, and co‐emitted species in landscape‐fire emissions are different from anthropogenic sources of PM2.5. The implications of landscape‐fire emissions on the sub‐national temporal and spatial distribution of health events and the relative health importance of specific pollutants within smoke are not well understood. We use a health impact assessment with observation‐based smoke PM2.5 to determine the sub‐national distribution of mortality and the sub‐national and sub‐annual distribution of asthma morbidity attributable to US smoke PM2.5 from 2006 to 2018. We estimate disability‐adjusted life years (DALYs) for PM2.5 and 18 gas‐phase hazardous air pollutants (HAPs) in smoke. Although the majority of large landscape fires occur in the western US, we find the majority of mortality (74%) and asthma morbidity (on average 75% across 2006–2018) attributable to smoke PM2.5 occurs outside the West, due to higher population density in the East. Across the US, smoke‐attributable asthma morbidity predominantly occurs in spring and summer. The number of DALYs associated with smoke PM2.5 is approximately three orders of magnitude higher than DALYs associated with gas‐phase smoke HAPs. Our results indicate awareness and mitigation of landscape‐fire smoke exposure is important across the US.
Electron Partial Density and Temperature Over Jupiter's Main Auroral Emission Using Juno Observations
Authors: Allegrini F. , Kurth W. S. , Elliott S. S. , Saur J. , Livadiotis G. , Nicolaou G. , Bagenal F. , Bolton S. , Clark G. , Connerney J. E. P. , Ebert R. W. , Gladstone G. R. , Louarn P. , Mauk B. H. , McComas D. J. , Sulaiman A. H. , Szalay J. R. , Valek P. W. , Wilson R. J.
Published: August 2021

We present a survey of electron partial densities (i.e., the portion of the total density measured between ∼0.05 and 100 keV) and temperatures in Jupiter's main auroral emission region using plasma measurements from the Jovian Auroral Distributions Experiment (JADE) on Juno. The electron partial density increases from ∼0.01 or 0.1 cm−3 near the main oval to a few cm−3 at the edge of the measurable part of the UV emission equatorward of the main oval. The electron temperature is highest near the main oval at ∼10–20 keV and decreases equatorward down to ∼0.3–2 keV. The JADE electron partial density agrees within a factor of ∼2 with the total electron densities derived from Juno‐Waves when the comparison is possible. The electron density and temperature trends are consistent for all sampled longitudes, for the north and the south, and there is no significant trend with radial distance in the range examined in this study (1.25–1.96 RJ). The electron density is anti‐correlated with the temperature and the characteristic energy. The ratio of the magnetic field strength to the electron density is maximum near the main oval.
The Importance of Counting: A New Index to Correctly Quantify Equatorial Plasma Bubble Occurrence in COSMIC Radio Occultation Data
Authors: Currie J. L. , Carter B. A. , Dao T. , Terkildsen M.
Published: August 2021

The Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Radio Occultation data has been previously used as a way of investigating the climatology of Equatorial Plasma Bubbles (EPB). These low‐density regions can cause random phase and amplitude scintillation of satellite signals and forecasting these is an important priority in the space physics community. The ability to build useful forecasting models depends on the underlying data sets used in testing and validating these models. Correctly identifying days of EPB activity is important, but statistical studies using large data sets require the use of automated detection methods. Many of these detection methods heavily reduce data sets by removing unfavorable data, such as COSMIC profiles where the maximum scintillation occurs in the E region. This study presents a new F region s4max9sec index that can be used to study the presence of F region scintillation without excluding profiles that exhibit E region scintillation. The new index is shown to decrease EPB occurrence through the increase in available data, and is also shown to detect EPB events previously excluded from climatological studies. Calculation of the climatology using the new index is shown to resolve some differences that exist in the EPB climatology literature, particularly the location of the maximum scintillation occurrence during the equinox seasons. The use of this index is highlighted as a potential for studying F region scintillation in the presence of E region scintillation; an area of research that needs to be expanded for a complete understanding of EPBs.
Marine Aerosol Records of Arctic Sea‐Ice and Polynya Variability From New Ellesmere and Devon Island Firn Cores, Nunavut, Canada
Authors: Criscitiello A. S. , Geldsetzer T. , Rhodes R. H. , Arienzo M. , McConnell J. , Chellman N. , Osman M. B. , Yackel J. J. , Marshall S.
Published: August 2021

Sea ice plays a critical role in the Earth’s climate system, including influencing ocean heat uptake, reflecting solar radiation, and contributing to dense water formation. Instrumental records of polar sea ice extent are only available since 1979, however. The short length of such records also limits our knowledge of polynya variability, which can reflect large‐scale atmospheric and climate changes. Ice core proxy records can extend these observations, but require further development and regional validation. We compare chloride and methanesulfonic acid concentrations from two new firn cores from the Canadian Arctic with satellite‐derived observations of regional sea‐ice concentration and polynya variability from 2002 to 2014. The sub‐annual resolution of these cores allows for detailed investigation of how regional sea‐ice concentration is recorded in the ice at Prince of Wales Icefield (POW), Ellesmere Island and Devon Ice Cap (DIC), Devon Island, Nunavut. Over the period 2002–2014 we find that the primary sources of marine aerosols to POW are polynyas within Arctic Canada and the Canada basin of the Arctic Ocean, whereas the primary sources of marine aerosols to DIC are a broader region of the Queen Elizabeth Islands, Baffin Bay, and the Arctic Ocean. Marine aerosol sources to the two core sites are distinct, reflecting different moisture source regions and, likely, differing transport pathways. Air mass back trajectory results support the satellite‐derived results. Glaciochemical records from this dynamic, warming region may provide a proxy for reconstructing North Water polynya and other regional polynya and shore‐lead variability prior to the satellite era.
Multiple Gamma‐Ray Glows and a Downward TGF Observed From Nearby Thunderclouds
Authors: Hisadomi S. , Nakazawa K. , Wada Y. , Tsuji Y. , Enoto T. , Shinoda T. , Morimoto T. , Nakamura Y. , Yuasa T. , Tsuchiya H.
Published: August 2021

Around 17:00 on January 12, 2020 (UTC), radiation detectors installed at two locations with a 1.35 km separation in Kanazawa City, Japan, captured a total of four gamma‐ray enhancements. The first pair was simultaneously observed at the two locations at 17:03 and were abruptly terminated by a lightning discharge. The remaining two enhancements were also nearly simultaneously observed 3 min later, and one of them was also terminated by another lightning discharge. At the last termination, a downward terrestrial gamma‐ray flash and a negative energetic in‐cloud pulse were observed. Both pairs were associated with thundercloud cells. In the first pair, simultaneous detection in two locations 1.35 km apart suggests either a gamma‐ray glow emerged in‐between and time variability of its intensity were directly observed or there were two (or more) gamma‐ray glows in the cell which reached the two detectors coincidentally. In the latter pair, the peak time in the downwind detector was 40 s later than that of the upwind detector. If the irradiation region moved with the cell, it would have taken ∼110 s. The discrepancy suggests either the glow moved 2.5 times faster than the cell or there were two (or more) glows in the cell. Also, the fact that the thunderstorm cell hosting the latter glows experienced the lightning discharge 3 min before suggests that the strong electric field in the cell can develop within a few minutes.
Global and Regional Estimation of Carbon Uptake Using CMIP6 ESM Compared With TRENDY Ensembles at the Centennial Scale
Authors: Peng Jing , Dan Li , Yang Fuqiang , Tang Xiba , Wang Dayong
Published: August 2021

To evaluate the ability of CMIP6 Earth System Models to simulate net biome production (NBP) changes caused by natural and man‐made forcing, the simulated NBP during the period 1901–2010 at global, hemispheric and regional scales was compared with the estimated NBP of the TRENDY ensemble. The annual NBP, globally and over the Northern Hemisphere and tropics, from the CMIP6 ensemble reflected well the TRENDY ensemble annual values from 1901 to 2010, and the correlation coefficient passed the 0.05 significance level. The annual NBP estimated by CMIP6 over the globe, Northern Hemisphere and tropics was 0.20 ± 0.46, 0.25 ± 0.34, and −0.02 ± 0.14 Pg C yr−1, respectively; while from the TRENDY ensemble it was 1.04 ± 0.41, 0.55 ± 0.24, and 0.43 ± 0.20 Pg C yr−1, respectively. The main weaknesses of the CMIP6 multi‐model ensemble simulation was the lower strength of NBP, especially at low latitudes. The simulated results showed higher soil respiration estimated by CMIP6 for these regions, especially in the Amazon Basin, than that by the TRENDY ensemble, which produced the greater NPB estimated by TRENDY. The CMIP6 ensemble exaggerated the increasing trend of carbon sinks between 30° and 60°N in the Northern Hemisphere after 1961, due to the stronger positive response of NPP (net primary production) in the high‐latitude Northern Hemisphere to global warming. The NBP during 1901–2010 could not be reproduced well by the CMIP6 ensemble in most sub‐regions, as evidenced by the failure to pass the statistical test at the 5% significance level in 70% of the sub‐regions in terms of the correlation coefficients with the TRENDY ensemble. In eastern Asia, for example, NBP was poorly estimated by the CMIP6 ensemble, as evidenced by negative correlation coefficients with the TRENDY ensemble.