bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Queuing Theory in Production Efficiency of Direct Rolling Process of Long Product
Authors: Zhang Hong Liang , Feng Guang Hong , Wang Bao Shan , Liu Xu Ming , Liu Xin
Published: February 2020

Based on the mathematical method of queuing theory, the queuing model of billets in the direct rolling process of the long product was established, which represented the conveying process of billets at the casting and rolling interface. Using the billets queuing model, the influence of different steel quantity, length, speed and other factors on the average waiting time of a single billet in the direct rolling production process was analyzed. Combined with the temperature drop of billets, the optimal average waiting time for a single billet was determined. The method improved the conveying connection efficiency of the casting-rolling interface and the direct rolling rate of billets.
The Interlayer Effects of Nitrogen Implantation in the TiN/N2- Film Synthesis on the NAK80 Steel
Authors: Hwang Un Hak
Published: February 2020

Nitrogen ions with an energy of 200keV were used for the investigation of the interlayer effects of nitrogen implantation in the TiN/N2-film synthesis on the NAK80 steel. The nitrogen ion plasmas formed a broad ion mixing area at the interface between TiN film and NAK80 substrate. The measured hardness indicates the well mixing of TiN film into the NAK80 substrate, which may have an effect on increasing the adhesion of the deposited film. The chemical components and micro-hardness of the filmed surface were measured. The micro-hardness of Rockwell C-scale (HRC) was increased from 40 to 61 after the films of TiN/N2 were synthesized on the NAK80 substrate, the increased micro-hardness is attributed to the metallurgical phase change and formation of amorphous crystal due to the nitrogen implantation.
Preparation and Characterization of Al2O3-B4C Coated Composite Powder by Hydrothermal Method
Authors: Wang Fang , Wang Rui Hua , Xu Min Han , Bai Xiao Bo , Chen Ai Xia , Du Da Ming , Li Shi Bin , Song Jie Guang , Chen Lin
Published: February 2020

Both alumina and boron carbide have good hardness and strength, and are widely used in production and life, industrial manufacturing, and military defense. However, due to the insufficiency of research at this stage and the lack of technical means, it is difficult to prepare alumina-boron carbide composite powder with good coating and ultra high strength through large-scale batch production. Therefore, this experiment wants to obtain a relatively good performance of coated Al2O3/B4C cermet by hydrothermal method through different experimental parameter ratios. Through the experimental results and analysis, the following conclusions are obtained. The most suitable concentration of aluminum nitrate is 0.1 mol/l. The low concentration affects the formation of alumina particles. The concentration is too high and prone to agglomeration. Through the optimization of hydrothermal synthesis concentration, a composite of Al2O3/B4C composite with good nanoencapsulated structure was obtained. The composite powder was pure in composition and high in specific surface area, which lays a foundation for solving the low-temperature preparation of high-density boron carbide ceramics.
Dysregulated NADPH Oxidase Promotes Bone Damage in Murine Model of Autoinflammatory Osteomyelitis
Authors: Kralova Jarmila , Drobek Ales , Prochazka Jan , Spoutil Frantisek , Fabisik Matej , Glatzova Daniela , Borna Simon , Pokorna Jana , Skopcova Tereza , Angelisova Pavla , Gregor Martin , Kovarik Pavel , Sedlacek Radislav , Brdicka Tomas
Published: February 2020

Autoinflammatory diseases are characterized by dysregulation of the innate immune system, leading to spontaneous inflammation. Pstpip2cmo mouse strain is a well-characterized model of this class of disorders. Because of the mutation leading to the lack of adaptor protein PSTPIP2, these animals suffer from autoinflammatory chronic multifocal osteomyelitis similar to several human syndromes. Current evidence suggests that it is driven by hyperproduction of IL-1β by neutrophil granulocytes. In this study, we show that in addition to IL-1β, PSTPIP2 also negatively regulates pathways governing reactive oxygen species generation by neutrophil NOX2 NADPH oxidase. Pstpip2cmo neutrophils display highly elevated superoxide production in response to a range of stimuli. Inactivation of NOX2 NADPH oxidase in Pstpip2cmo mice did not affect IL-1β levels, and the autoinflammatory process was initiated with similar kinetics. However, the bone destruction was almost completely alleviated, suggesting that dysregulated NADPH oxidase activity is a key factor promoting autoinflammatory bone damage in Pstpip2cmo mice.
Critical Role for SLAM/SAP Signaling in the Thymic Developmental Programming of IL-17– and IFN-γ–Producing γδ T Cells
Authors: Dienz Oliver , DeVault Victoria L. , Musial Shawn C. , Mistri Somen K. , Mei Linda , Baraev Aleksandr , Dragon Julie A. , Krementsov Dimitry , Veillette Andre , Boyson Jonathan E.
Published: February 2020

During thymic development, mouse γδ T cells commit to either an IFN-γ– or an IL-17–producing phenotype through mechanisms that remain unclear. In this study, we investigated the extent to which the SLAM/SAP signaling pathway regulates the functional programming of γδ T cells. Characterization of SLAM family receptor expression revealed that thymic γδ T cell subsets were each marked by distinct coexpression profiles of SLAMF1, SLAMF4, and SLAMF6. In the thymus, Vγ1 and Vγ4 T cells that exhibited an SLAMF1+SLAMF6+ double positive phenotype were largely contained within immature CD24+CD73− and CD24+CD73+ subsets, whereas SLAMF1 single positive, SLAMF6 single positive, or SLAMF1SLAMF6 double negative cells were found within mature CD24−CD73+ and CD24−CD73− subsets. In the periphery, SLAMF1 and SLAMF6 expression distinguished IL-17– and IFN-γ–producing γδ T cells, respectively. Disruption of SLAM family receptor signaling through deletion of SAP resulted in impaired thymic Vγ1 and Vγ4 T cell maturation at the CD24+CD73−SLAMF1+SLAMF6+ double positive stage that was associated with a decreased frequency of CD44+RORγt+ γδ T cells. Impaired development was in turn associated with decreased γδ T cell IL-17 and IFN-γ production in the thymus as well as in peripheral tissues. The role for SAP was subset-specific, as Vγ1Vδ6.3, Vγ4, Vγ5, but not Vγ6 subsets were SAP-dependent. Together, these data suggest that the SLAM/SAP signaling pathway plays a larger role in γδ T cell development than previously appreciated and represents a critical checkpoint in the functional programming of both IL-17– and IFN-γ–producing γδ T cell subsets.
Highlights on the Management of Oligometastatic Disease
Authors: Alshehri Salem M. , Alkattan Khaled , Abdelwarith Ahmed , Alhussain Hussain , Shaker Shaker , Alghamdi Majed , Alassaf Hossam , Albargawi Ali , Naimi Manal Al , Alomair Ameen , Althaqfi Saif , Alhebshi Adnan , Alothman Majid , Jazieh AbdulRahman
Published: February 2020

Purpose: The understanding of oligometastatic disease (OMD) is rapidly evolving and with this comes the ability to utilize a number of modalities that excel in the localized control of disease. It has been identified that there are no clear guidelines based on high-level evidence to standardized approaches toward the management of OMD. These highlights have been developed to provide a road map for all health-care professionals who are involved in the management of OMD to support standardized patient care. Methods: The Saudi Lung Cancer Guidelines Committee is a part of the Saudi Lung Cancer Association which, in turn, is part of the Saudi Thoracic Society. Considering that lung cancer constitutes a major proportion of OMD prevalence, the committee took the initiative to develop national highlights to support the management of OMD within Saudi Arabia. The committee members are national clinical leaders who collaborated with international expertise to establish these highlights to serve as a general clinical pathway in the management of OMD. Results: Standardization of the indications to diagnose oligometastases and patient selection criteria including ineligibility criteria for treatment are the basis of the highlights. Treatment approaches including surgical and the variety of radiotherapeutical options are discussed in relation to specific oligometastatic sites. Acceptable measurements for response to treatment and the future for the treatment of OMD conclude the development of the highlights. Conclusion: These are the first national highlights addressing this important disease in oncology. The implementation of these highlights as guidelines requires a robust multidisciplinary team and access to specific technology and expertise. These highlights are based on the most recent findings within the literature but will require repeated review and updating due to this rapidly evolving field in disease management.
Visual acuity assessment and the knowledge of road safety rules among commercial motorcyclist in Ekpoma town, Southern Nigeria
Authors: Alenoghena Innocent O. , Awunor N.S. , Ovienra W.A.
Published: February 2020

Introduction:

Motorcycle injuries, particularly from low income countries like Africa and Asia contribute significantly to road traffic injuries globally, according to recent estimates by the World Health Organization.

Objective:

To determine the prevalence of visual acuity disorders, knowledge of road safety rules and one-year prevalence of road crashes in male commercial motorcyclists. Methodology: Male commercial motorcyclists numbering 191 were selected from the motorcycles’ parks in Ekpoma, using a multi-staged random sampling technique. Structured interviewer administered questionnaires were used for data collection. Data were analysed using SPSS version 20.

Results:

A vast majority 189 (99.0%) of respondents had good visual acuity (with visual acuity of between 6/5 and 6/18), Just one percent of the respondents had poor visual acuity (between 6/24 to 6/60). Most respondents 122 (63%) had a good knowledge of road safety rules while 42.9% had been involved in at least a road traffic crash within a year prior to the survey. Knowledge of road safety rules showed a statistically significant association with the educational status of the respondents (P<0.001), but had no association with other socio demographic variables like age (P=0.184), marital status (P=0.298) and religion (P=0.511) in respondents.

Conclusion:

Majority of the male motorcyclist had visual acuity within the normal range, knowledge of road safety rules was good among respondents with the level of education identified as a significant predictor of knowledge Inclusion of at least primary school educational qualification as criteria for all motorcyclists and a proper medical examination of prospective motorcyclists before issuance of driver licenses.
دراسة تغير الأوزون الكلي فوق بعض مدن المملكة العربية السعودية خلال عام 2004 م
Authors: عبدالرحمن خلف الخلف عبدالرحمن خلف الخلف
Published: February 2020

تمت الدراسة باستخدام بيانات الأوزون الكلية فوق بعض المدن الكبرى في المملكة العربية السعودية لمعرفة التغير الزماني والتغير المكاني باستخدام طرق إحصائية وطرق بيانية، حيث تهدف هذه الدراسة إلى معرفة التغيرات اليومية والشهرية والفصلية والسنوية، كما تشير الدراسة إلى مقارنة قيم الأوزون بين تلك المناطق. وقد أخذت البيانات بواسطة جهاز قياس قيم الأوزون الكيلة ،Total Mapping Ozone Spectrometer (TOMS) لعام 2004م على متن القمر الاصطناعي Nimbus-7 حيث تستخدم هذه البيانات لمعرفة تغير الأوزون فوق المدن التي تم اختيارها للدراسة وهي تبوك ، الظهران ، الرياض ، المدينة ، جدة ، وأبها حيث تقع ما بين خطي عرض 18 درجة و 28 درجة شمالاً. لقد وجد أن الأوزون له تغيرات زمنية مختلفة فعلى مستوى التغيرات اليومية تكون متغيرة بشكل متكرر حيث بلغت أعلى قيمة 344 دوبسون فوق مدينة تبوك وأقل قيمة بلغت 209 دوبسون فوق مدينة أبها، كما بلغ أعلى متوسط يوم 269 دوبسون فوق مدينة تبوك وأقل متوسط يومي بلغ 257 دوبسون فوق ميدنة أبها. بلغ المدى اليومي لمدينة تبوك 134 دوبسون أي ما يقارب 50% من المتوسط الحسابي بينما يتراوح المدى لبقية إلى ما يقارب ارتفاع 50 كيلو متر ، وتبين أن أكبر تركيز له يقع بين ارتفاع 19ـ23كم (Kowalok, 1993). إن ما حدث في طبقة الأوزون أخذ أنظار دوائر الأبحاث ومراكز الدراسات في شتى فروع العلم المختلفة، وكان محط اهتمام الجهات المعنية التي أولته عناية فائقة، وطالبت بإزالة أسباب حدوث ذلك الثقب في طبقة الأوزون، لأن هذا الخلل في تلك الطبقة يحدث أضرارا غير مضمونة العواقب على المخلوقات الأرضية كلها بلا استثناء، ولذلك يعتبر ثقب الأوزون من قضايا الساعة ذات الأهمية في زماننا الحاضر فالأوزون ضروري لحياة البشر أجمع. تتأثر طبقة الأوزون بالتفاعلات الكيميائية الناجمة عن الغازات المتصاعدة إلى الطبقات العليا من الغلاف الجوي المحيط بالأرض ، حيث أن أغلب الأوزون الجوي موجود في طبقة الأستراتوسفير، وتأتي أشعة الشمس لتكمل العملية الكيميائية التي تحدث تغيرا في تركيز الأوزون. فالأوزون كغاز، هو شكل من أشكال الأكسجين، بينما يحتوي الأكسجين العادي على ذرتين فقط، ويوجد الأوزون بكميات مختلفة في الغلاف الجوي المحيط بالأرض. وهناك العديد من العمليات الكيميائية تحدث في طبقة الأوزون، فجزيئات الأكسجين الموجودة بوفرة في طبقة الاستراتوسفير تنقسم إلى ذرات مفردة (O+O) عندما تمتص الإشعاع القادم من الشمس. وهذه الذرات الحرة تتحد بجزئيات أكسجين أخرى مكونة الأوزون، Houghton, 1986 )(O3)). وتقوم جزئيات الأوزون بامتصاص الإشعاع الشمسي من الأطوال الموجية فوق البنفسجية التي تضر بالحياة إذا هي نفذت إلى سطح الأرض. على الرغم من التحلل الذي يصيب الأوزون بصورة طبيعية بفعل الأشعة فوق البنفسجية، فإن هذا التحلل وإعادة البناء يتم في دورة متسلسلة تسهم فيها الأشعة فوق البنفسجية نفسها، وهذا التسلسل يحافظ على نسبة موازنة لغاز الأوزون في طبقة الاستراتوسفير. غير أن بعض المركبات والعناصر الكيميائية التي بدأت تدخل الجو بشكل ملحوظ منذ بداية الثورة الصناعية في العالم، أحدثت وما زالت تحدث تغيرات ملحوظة في نسب هذا الغاز في الغلاف الجوي. تؤثر حركة الهواء في طبقة الاستراتوسفير بشكل رئيس في تحديد التوزيع المكاني والزماني للأوزون، حيث يرتفع الهواء إلى طبقة الاستراتوسفير في المناطق المدارية، ثم على المدن المختارة للتعرف على التغير المكاني، وبالتالي يتم التوصل إلى فهم تغيرات الأوزون ومسلكه خلال هذا العام على المناطق المختلفة للمملكة العربية السعودية .
تأثير الكثافة النباتية والأزوت على السلوك الفلاحي لزهرة دوار الشمس بالمناطق الجافة
Authors: حسين الجزولي عثمان حسين الجزولي عثمان
Published: February 2020

أجريت التجارب الحقلية لمدة عامين لدراسة تأثير الكثافة النباتية ومستوى الأزوت على الزراعة المتأخرة لزهرة دورا الشمس ، وشملت الدراسة وزن المحصول وصفات أخرى بالناطق الجافة بوسط السودان. ففي التجربة الأولى زرع الصنفان Hungarian A, Cerninka ) تحت كثافتين ( 83.333 و 166.666 نبات للهكتار ) وثلاثة مستويات أزوتية ( صفر ، 40 ، 80كجم للهكتار ) أما في التجربة الثانية فقد زرع الصنفان ( Cerninka, Bolero ) عند نفس المستويات الأزوتية وعند كثافة نباتية 83.333 و 41.666 نبات للهكتار. اختلفت إنتاجية الصنف Hungarian A في التجربة الأولى معنويا عن الصنف Cerninka بزيادة قدرها 32.7% كما تفوق الصنف Bolero تفوقاً معنويا وبزيادة 29.1% على الصنف Cerninka في التجربة الثانية . وتحت ظروف التجربة الأولى أدت معاملة الأزوت الثانية (40كجم/هكتار) لزيادة معنوية في الإنتاجية وطول النبات، عدد النباتات المحصودة للهكتار وقطر الرأس ووزن الألف حبة . كذلك أدت الزراعة عند المستوى الأدنى ( 83.333 نبات / هكتار ) على العكس من الزراعة عند المستوى الأعلى ( 166.666 نبات / هكتار ) للزيادة المعنوية في الإنتاجية ووزن الألف حبة وإلى النقص المعنوي في عدد النباتات للهكتار. أما في التجربة الثانية فقد أدى التسميد بمعدل 40كجم أزوت للهكتار إلى نقص معنوي في طول النبات وعدد البذور المليئة بالرأس بينما أدت الكثافة النباتية الدنيا (41.666) إلى نقص معنوي في عدد النباتات المحصودة. وفي كلا التجربتين لم يؤثر التسميد بمعدل 80 كجم أزوت/ هكتار معنويا على أي من الصفات التي درست. إذا استبعدنا صفة عدد البذور المليئة بالرأس ( التجربة الأولى ) فإن كل تفاعلات المستوى الأول ( التجربة الأولى ) والمستوى الثاني ( التجربتين ) بين العوامل الثلاثة التي درست كانت معنوية مما يدل على ضرورة إجراء البرامج الانتخابية لتحسين محصول زهرة دوار الشمس تحت معدلات سمادية وكثافات نباتية مختلفة. ويبدو من الدراسة أن المعدلات : 83.333 نبات كحد أدنى و 40 كجم أزوت كحد أقصى للهكتار هما أنسب المعدلات للحصول على إنتاجية أعلى للزراعات المتأخرة لزهرة دوار الشمس بالمناطق المدارية الجافة .
دراسة مقارنة للطرق المختلفة لتقدير الإشعاع الشمسي الكلي فوق مدينة جدة
Authors: محمد أيمن عبد الله محمد أيمن عبد الله
Published: February 2020

قياسات الإشعاع الشمسي وحساباته مهمة جدا لدراسات الطاقة البديلة في العالم. وفي المنطقة شبه المدارية تزداد أهمية مدة سطوع الشمس حيث يصل المتوسط اليومي إلى 10 ساعات أو أكثر . وهي تستقبل أكبر كمية من أشعة الشمس في العالم . استخدمت العديد من المعادلات التجريبية لحساب الإشعاع الشمسي حيث إن حساب الإشعاع الشمسي الكلي على سطح الأرض مرتبط بعدد من عناصر الأرصاد الجوية مثل مدة سطوع الشمس والرطوبة النسبية ودرجة الحرارة . وفي هذه الدراسة تم اختبار عدد من المعادلات التجريبية وشبه التجريبية لحساب الإشعاع الكلي للأيام الصافية خلال أشهر فبراير ومارس وأبريل للسنوات 86-87-88م . وجد أن معادلتي العدوى وجولدبيرج أعطت أفضل النتائج الحسابية وكان الاختلاف بين القياس والحساب من 5% إلى 10% بينما في المعادلات الأخرى من 15% إلى 25% .
A note on observational equivalence of micro assumptions on macro level
Authors: Ponomarenko Alexey A.
Published: February 2020

The author set up a simplistic agent-based model where agents learn with reinforcement observing an incomplete set of variables. The model is employed to generate an artificial dataset that is used to estimate standard macro econometric models. The author shows that the results are qualitatively indistinguishable (in terms of the signs and significances of the coefficients and impulse-responses) from the results obtained with a dataset that emerges in a genuinely rational system.
Diurnal cycle of the semi-direct effect from a persistent absorbing aerosol layer over marine stratocumulus in large-eddy simulations
Authors: Herbert Ross J. , Bellouin Nicolas , Highwood Ellie J. , Hill Adrian A.
Published: February 2020

Abstract. The rapid adjustment, or semi-direct effect, of marine stratocumulus clouds
to elevated layers of absorbing aerosols may enhance or dampen the radiative
effect of aerosol–radiation interactions. Here we use large-eddy
simulations to investigate the sensitivity of stratocumulus clouds to the
properties of an absorbing aerosol layer located above the inversion layer,
with a focus on the location, timing, and strength of the radiative heat
perturbation. The sign of the daily mean semi-direct effect depends on the
properties and duration of the aerosol layer, the properties of the boundary
layer, and the model setup. Our results suggest that the daily mean
semi-direct effect is more elusive than previously assessed. We find that
the daily mean semi-direct effect is dominated by the distance between the
cloud and absorbing aerosol layer. Within the first 24 h the
semi-direct effect is positive but remains under 2 W m−2 unless the
aerosol layer is directly above the cloud. For longer durations, the daily
mean semi-direct effect is consistently negative but weakens by 30 %,
60 %, and 95 % when the distance between the cloud and aerosol layer is
100, 250, and 500 m, respectively. Both the cloud response and semi-direct
effect increase for thinner and denser layers of absorbing aerosol.
Considerable diurnal variations in the cloud response mean that an
instantaneous semi-direct effect is unrepresentative of the daily mean and
that observational studies may underestimate or overestimate semi-direct
effects depending on the observed time of day. The cloud response is
particularly sensitive to the mixing state of the boundary layer: well-mixed
boundary layers generally result in a negative daily mean semi-direct
effect, and poorly mixed boundary layers result in a positive daily mean
semi-direct effect. The properties of the boundary layer and model setup,
particularly the sea surface temperature, precipitation, and properties of
the air entrained from the free troposphere, also impact the magnitude of
the semi-direct effect and the timescale of adjustment. These results
suggest that the semi-direct effect simulated by coarse-resolution models
may be erroneous because the cloud response is sensitive to small-scale
processes, especially the sources and sinks of buoyancy.
Mapping the drivers of uncertainty in atmospheric selenium deposition with global sensitivity analysis
Authors: Feinberg Aryeh , Maliki Moustapha , Stenke Andrea , Sudret Bruno , Peter Thomas , Winkel Lenny H. E.
Published: February 2020

Abstract. An estimated 0.5–1 billion people globally have inadequate intakes of selenium (Se), due to a lack of bioavailable Se in agricultural soils. Deposition from the atmosphere, especially through precipitation, is an important source of Se to soils. However, very little is known about the atmospheric cycling of Se. It has therefore been difficult to predict how far Se travels in the atmosphere and where it deposits. To answer these questions, we have built the first global atmospheric Se model by implementing Se chemistry in an aerosol–chemistry–climate model, SOCOL-AER (modeling tools for studies of SOlar Climate Ozone Links – aerosol). In the model, we include information from the literature about the emissions, speciation, and chemical transformation of atmospheric Se. Natural processes and anthropogenic activities emit volatile Se compounds, which oxidize quickly and partition to the particulate phase. Our model tracks the transport and deposition of Se in seven gas-phase species and 41 aerosol tracers. However, there are large uncertainties associated with many of the model's input parameters. In order to identify which model uncertainties are the most important for understanding the atmospheric Se cycle, we conducted a global sensitivity analysis with 34 input parameters related to Se chemistry, Se emissions, and the interaction of Se with aerosols. In the first bottom-up estimate of its kind, we have calculated a median global atmospheric lifetime of 4.4 d (days), ranging from 2.9 to 6.4 d (2nd–98th percentile range) given the uncertainties of the input parameters. The uncertainty in the Se lifetime is mainly driven by the uncertainty in the carbonyl selenide (OCSe) oxidation rate and the lack of tropospheric aerosol species other than sulfate aerosols in SOCOL-AER. In contrast to uncertainties in Se lifetime, the uncertainty in deposition flux maps are governed by Se emission factors, with all four Se sources (volcanic, marine biosphere, terrestrial biosphere, and anthropogenic emissions) contributing equally to the uncertainty in deposition over agricultural areas. We evaluated the simulated Se wet deposition fluxes from SOCOL-AER with a compiled database of rainwater Se measurements, since wet deposition contributes around 80 % of total Se deposition. Despite difficulties in comparing a global, coarse-resolution model with local measurements from a range of time periods, past Se wet deposition measurements are within the range of the model's 2nd–98th percentiles at 79 % of background sites. This agreement validates the application of the SOCOL-AER model to identifying regions which are at risk of low atmospheric Se inputs. In order to constrain the uncertainty in Se deposition fluxes over agricultural soils, we should prioritize field campaigns measuring Se emissions, rather than laboratory measurements of Se rate constants.
Assessment of natural and anthropogenic aerosol air pollution in the Middle East using MERRA-2, CAMS data assimilation products,and high-resolution WRF-Chem model simulations
Authors: Ukhov Alexander , Mostamandi Suleiman , da Silva Arlindo , Flemming Johannes , Alshehri Yasser , Shevchenko Illia , Stenchikov Georgiy
Published: February 2020

Abstract. Modern-Era Retrospective analysis for Research and Applications v.2 (MERRA-2), Copernicus Atmosphere Monitoring Service Operational Analysis (CAMS-OA) data assimilation products, and a regional Weather Research and Forecasting model (10 km resolution) coupled with Chemistry (WRF-Chem) were used to evaluate natural and anthropogenic aerosol air pollution in the ME during 2015–2016. Satellite and ground-based AOD observations, as well as in-situ Particulate Matter (PM) measurements for 2016, were used for validation. WRF-Chem code was modified to correct the calculation of dust gravitational settling and aerosol optical properties. The dust emission in WRF-Chem is calibrated to fit Aerosol Optical Depth (AOD) and aerosol volume size distributions obtained from Aerosol Robotic Network (AERONET) observations. MERRA-2 was used to construct WRF-Chem initial and boundary conditions both for meteorology and chemical/aerosol species. SO2 emissions in WRF-Chem are based on the novel NASA SO2 emission dataset that reveals unaccounted sources over the ME. Although aerosol fields in WRF-Chem and assimilation products are quite consistent, WRF-Chem, due to its higher spatial resolution and better SO2 emissions, is preferable for analysis of regional air-quality over the ME. The WRF-Chem's PM background concentrations exceed the World Health Organization (WHO) guidelines over the entire ME. The major contributor to PM (~ 75–95 %) is mineral dust. In the ME urban centers and near oil recovery fields, non-dust aerosols (primarily sulfate) contribute up to 26 % into PM2.5. The contribution of sea salt into PM can rich up to 5 %. The contribution of organic matter into PM prevails over black carbon.
Source attribution of Arctic aerosols and associated Arctic warming trend during 1980–2018
Authors: Ren Lili , Yang Yang , Wang Hailong , Zhang Rudong , Wang Pinya , Liao Hong
Published: February 2020

Abstract. Observations show that the concentrations of Arctic sulfate and black carbon (BC) aerosols have declined since the early 1980s, which potentially contributed to the recent rapid Arctic warming. In this study, a global aerosol-climate model equipped with an Explicit Aerosol Source Tagging (CAM5-EAST) is applied to quantify the source apportionment of aerosols in the Arctic from sixteen source regions and the role of aerosol variations in the Arctic surface temperature change over the past four decades (1980–2018). The CAM5-EAST simulated surface concentrations of sulfate and BC in the Arctic had a decrease of 43 % and 23 %, respectively, in 2014–2018 relative to 1980–1984, mainly due to the reduction of emissions from Europe, Russia and Arctic local sources. Increases in emissions from South and East Asia led to positive trends of Arctic sulfate and BC in the upper troposphere. Changes in radiative forcing of sulfate and BC through aerosol-radiation interactions are found to exert a +0.145 K Arctic surface warming during 2014–2018 with respect to 1980–1984, with the largest contribution (61 %) by sulfate decrease, especially originating from the mid-latitude regions. The changes in atmospheric BC outside the Arctic produced an Arctic warming of +0.062 K, partially offset by −0.005 K of cooling due to atmospheric BC within the Arctic and −0.041 K related to the weakened snow/ice albedo effect of BC. Through aerosol-cloud interactions, the sulfate reduction gave an Arctic warming of +0.193 K between the first and last five years of 1980–2018, the majority of which is due to the mid-latitude emission change. Our results suggest that changes in aerosols over the mid-latitudes of the Northern Hemisphere have a larger impact on Arctic temperature than other regions associated with enhanced poleward heat transport from the aerosol-induced stronger meridional temperature gradient. The combined aerosol effects of sulfate and BC together produce an Arctic surface warming of +0.297 K during 1980–2018, explaining approximately 20 % of the observed Arctic warming during the same time period.
Advanced hodograph-based analysis technique to derive gravity-wave parameters from lidar observations
Authors: Strelnikova Irina , Baumgarten Gerd , Lübken Franz-Josef
Published: February 2020

Abstract. An advanced hodograph-based analysis technique to derive gravity-wave (GW) parameters from observations of temperature and winds is developed and presented as a step-by-step recipe with justification for every step in such an analysis. As the most adequate background removal technique the 2-D FFT is suggested. For an unbiased analysis of fluctuation whose amplitude grows with height exponentially, we propose applying a scaling function of the form exp (z∕(ςH)), where H is scale height, z is altitude, and the constant ς can be derived by a linear fit to the fluctuation profile and should be in the range 1–10.
The most essential part of the proposed analysis technique consists of fitting cosine waves to simultaneously measured profiles of zonal and meridional winds and temperature and subsequent hodograph analysis of these fitted waves.
The linear wave theory applied in this analysis is extended by introducing a wave packet envelope term exp⁡(-(z-z0)2/2σ2) that accounts for limited extent of GWs in the observational data set. The novelty of our approach is that its robustness ultimately allows for automation of the hodograph analysis and resolves many more GWs than can be inferred by the manually applied hodograph technique. This technique allows us to unambiguously identify upward- and downward-propagating GWs and their parameters.
This technique is applied to unique lidar measurements of temperature and horizontal winds measured in an altitude range of 30 to 70 km.
Recommendations for spectral fitting of SO2 from MAX-DOAS measurements
Authors: Davis Zoë Y. W. , McLaren Robert
Published: February 2020

Abstract. Fitting SO2 dSCDs from MAX-DOAS measurements of scattered sunlight is challenging because actinic light intensity is low in wavelength regions where the SO2 absorption features are strongest. SO2 dSCDs were fit with different wavelength windows (λlow to λhigh) from ambient measurements with calibration cells of 2.2 × 1017 and 2.2 × 1016 molec cm−2 inserted in the light path at different viewing elevation angles. SO2 dSCDs were the least accurate and fit errors were the largest for fitting windows with λlow  312 nm. The SO2 dSCDs also exhibited an inverse relationship with the SO2 absorption cross-section for fitting windows with λlow  400 nm. Deviation of the SO2 dSCD from the true value depended on the SO2 concentration for some fitting windows rather than exhibiting a consistent bias. Uncertainties of the SO2 dSCD reported by the fit algorithm were significantly less than the true error for many windows, particularly for the measurements without the filter or offset function. For retrievals with the filter or offset function, increasing λhigh > 320 nm tended to decrease the reported fit uncertainty but did not increase the accuracy. Based on the results of this study, a short-pass filter and a fitting window of 307.5
Equatorial plasma bubbles developing around sunrise observed by an all-sky imager and global navigation satellite system network during storm time
Authors: Wu Kun , Xu Jiyao , Yue Xinan , Xiong Chao , Wang Wenbin , Yuan Wei , Wang Chi , Zhu Yajun , Luo Ji
Published: February 2020

Abstract. A large number of studies have shown that equatorial plasma
bubbles (EPBs) occur mainly after sunset, and they usually drift eastward.
However, in this paper, an unusual EPB event was simultaneously observed by
an all-sky imager and the global navigation satellite system (GNSS) network
in southern China, during the recovery phase of a geomagnetic storm that happened
on 6–8 November 2015. Observations from both techniques show that the EPBs
appeared near dawn. Interestingly, the observational results show that the
EPBs continued to develop after sunrise, and they disappeared about 1 h
after sunrise. The development stage of EPBs lasted for at least about 3 h. To our knowledge, this is the first time that the evolution of EPBs
developing around sunrise was observed by an all-sky imager and the GNSS
network. Our observation showed that the EPBs drifted westward, which was
different from the usual eastward drifts of post-sunset EPBs. The
simulation from the Thermosphere–Ionosphere–Electrodynamics General Circulation Model (TIE-GCM) suggest that the westward drift of EPBs should
be related to the enhanced westward winds at storm time. Besides this,
bifurcation and merging processes of EPBs were observed by the all-sky
imager in the event. Associated with the development of EPBs, an increase in
the peak height of the ionospheric F region was also observed near sunrise, and we
suggest the enhanced upward vertical plasma drift during the geomagnetic storm
plays a major role in triggering the EPBs near sunrise.
Leaf wax n-alkane patterns and compound-specific δ13C of plants and topsoils from semi-arid and arid Mongolia
Authors: Struck Julian , Bliedtner Marcel , Strobel Paul , Schumacher Jens , Bazarradnaa Enkhtuya , Zech Roland
Published: February 2020

Abstract. Leaf wax n-alkane patterns and their compound-specific δ13C signatures are valuable proxies for paleoenvironmental reconstructions. So far, their potential has not been investigated in semi-arid to arid Mongolia. We have therefore analysed the leaf wax n-alkanes and their compound-specific δ13C signature of five plant species (Poaceae, Cyperaceae, Artemisia spp., Caragana spp. and Larix sp.) and topsoils (0–5 cm) along two transects in central and southern Mongolia. Grasses show a distinct dominance of the n-C31 homologue, whereas the shrubs Caragana spp. and Artemisia spp. are dominated by n-C29. Larix sp. is characterised by the mid-chain n-alkanes n-C23 and n-C25. From plant to topsoil, n-alkane patterns show the potential to differentiate between grass-covered sites from those covered by Caragana spp. n-Alkane concentrations and odd-over-even predominance (OEP) of the topsoils are distinctly influenced by mean annual temperature, mean annual precipitation and aridity, likely reflecting the degree of n-alkane degradation and biomass production. In contrast, the average chain length (ACL) and the n-alkane ratio (n-C31∕n-C29+n-C31) are not affected by climatic parameters and, thus, are not biased by climate. The compound-specific δ13C signatures are strongly correlated to climate, showing a significant enrichment with increasing aridity, indicating the effect of water use efficiency. Our calibration results suggest that long-chain n-alkanes and their compound-specific δ13C signatures have great potential to reconstruct paleoenvironmental and paleoclimatic conditions when used in sediment archives from Mongolia.
Dissolved organic carbon mobilized from organic horizons of mature and harvested black spruce plots in a mesic boreal region
Authors: Bowering Keri L. , Edwards Kate A. , Prestegaard Karen , Zhu Xinbiao , Ziegler Susan E.
Published: February 2020

Abstract. Boreal forests are subject to a wide range of temporally and
spatially variable environmental conditions driven by season, climate, and
disturbances such as forest harvesting and climate change. We captured
dissolved organic carbon (DOC) from surface organic (O) horizons in a boreal
forest hillslope using passive pan lysimeters in order to identify controls
and hot moments of DOC mobilization from this key C source. We specifically
addressed (1) how DOC fluxes from O horizons vary on a weekly to seasonal
basis in forest and paired harvested plots and (2) how soil temperature,
soil moisture, and water input relate to DOC flux trends in these plots over
time. The total annual DOC flux from O horizons contain contributions from
both vertical and lateral flow and was 30 % greater in the harvested plots
than in the forest plots (54 g C m−2 vs. 38 g C m−2, respectively;
p=0.008). This was despite smaller aboveground C inputs and smaller soil organic carbon stocks in the harvested plots but analogous to larger annual O horizon
water fluxes measured in the harvested plots. Water input, measured as rain, throughfall, and/or snowmelt depending on season and plot type, was
positively correlated to variations in O horizon water fluxes and DOC fluxes
within the study year. Soil temperature was positively correlated to
temporal variations of DOC concentration ([DOC]) of soil water and
negatively correlated with water fluxes, but no relationship existed between
soil temperature and DOC fluxes at the weekly to monthly scale. The relationship between water input to soil and DOC fluxes was seasonally
dependent in both plot types. In summer, a water limitation on DOC flux
existed where weekly periods of no flux alternated with periods of large
fluxes at high DOC concentrations. This suggests that DOC fluxes were water-limited and that increased water fluxes over this period result in
proportional increases in DOC fluxes. In contrast, a flushing of DOC from O
horizons (observed as decreasing DOC concentrations) occurred during
increasing water input and decreasing soil temperature in autumn, prior to
snowpack development. Soils of both plot types remained snow-covered all
winter, which protected soils from frost and limited percolation. The
largest water input and soil water fluxes occurred during spring snowmelt
but did not result in the largest fluxes of DOC, suggesting a production
limitation on DOC fluxes over both the wet autumn and snowmelt periods.
While future increases in annual precipitation could lead to increased DOC
fluxes, the magnitude of this response will be dependent on the type and
intra-annual distribution of this increased precipitation.
The Iso2k Database: A global compilation of paleo-δ18O and δ2H
records to aid understanding of Common Era climate
Authors: Konecky Bronwen L. , McKay Nicholas P. , Churakova (Sidorova) Olga V. , Comas-Bru Laia , Dassié Emilie P. , DeLong Kristine L. , Falster Georgina M. , Fischer Matt J. , Jones Matthew D. , Jonkers Lukas , Kaufman Darrell S. , Leduc Guillaume , Managave Shreyas R. , Martrat Belen , Opel Thomas , Orsi Anais J. , Partin Judson W. , Sayani Hussein R. , Thomas Elizabeth K. , Thompson Diane M. , Tyler Jonathan J. , Abram Nerilie J. , Atwood Alyssa R. , Conroy Jessica L. , Kern Zoltán , Porter Trevor J. , Stevenson Samantha L. , von Gunten Lucien ,   the Iso2k Project Members
Published: February 2020

Abstract. Reconstructions of global hydroclimate during the Common Era (CE; the past ~ 2000 years) are important for providing context for current and future global environmental change. Stable isotope ratios in water are quantitative indicators of hydroclimate on regional to global scales, and these signals are encoded in a wide range of natural geologic archives. Here we present the Iso2k database, a global compilation of previously published datasets from a variety of natural archives that record the stable oxygen (δ18O) or hydrogen (δ2H) isotopic composition of environmental waters, which reflect hydroclimate changes over the CE. The Iso2k database contains 756 isotope records from the terrestrial and marine realms, including: glacier and ground ice (205); speleothems (68); corals, sclerosponges, and mollusks (145); wood (81); lake sediments and other terrestrial sediments (e.g., loess) (158); and marine sediments (99). Individual datasets have temporal resolutions ranging from sub-annual to centennial, and include chronological data where available. A fundamental feature of the database is its comprehensive metadata, which will assist both experts and non-experts in the interpretation of each record and in data synthesis. Key metadata fields have standardized vocabularies to facilitate comparisons across diverse archives and with climate model simulated fields. This is the first global-scale collection of water isotope proxy records from multiple types of geological and biological archives. It is suitable for evaluating hydroclimate processes through time and space using large-scale synthesis, model-data intercomparison and (paleo)data assimilation. The Iso2k database is available for download at: https://doi.org/10.6084/m9.figshare.11553162 (McKay and Konecky, 2020).
ACCESS-OM2 v1.0: a global ocean–sea ice model at three resolutions
Authors: Kiss Andrew E. , Hogg Andrew McC. , Hannah Nicholas , Boeira Dias Fabio , Brassington Gary B. , Chamberlain Matthew A. , Chapman Christopher , Dobrohotoff Peter , Domingues Catia M. , Duran Earl R. , England Matthew H. , Fiedler Russell , Griffies Stephen M. , Heerdegen Aidan , Heil Petra , Holmes Ryan M. , Klocker Andreas , Marsland Simon J. , Morrison Adele K. , Munroe James , Nikurashin Maxim , Oke Peter R. , Pilo Gabriela S. , Richet Océane , Savita Abhishek , Spence Paul , Stewart Kial D. , Ward Marshall L. , Wu Fanghua , Zhang Xihan
Published: February 2020

Abstract. We introduce ACCESS-OM2, a new version of the ocean–sea ice model of the Australian Community Climate and Earth System Simulator.
ACCESS-OM2 is driven by a prescribed atmosphere (JRA55-do) but has been designed to form the ocean–sea ice component of the fully coupled (atmosphere–land–ocean–sea ice) ACCESS-CM2 model.
Importantly, the model is available at three different horizontal resolutions: a coarse resolution (nominally 1∘ horizontal grid spacing), an eddy-permitting resolution (nominally 0.25∘), and an eddy-rich resolution (0.1∘ with 75 vertical levels); the eddy-rich model is designed to be incorporated into the Bluelink operational ocean prediction and reanalysis system.
The different resolutions have been developed simultaneously, both to allow for testing at lower resolutions and to permit comparison across resolutions.
In this paper, the model is introduced and the individual components are documented.
The model performance is evaluated across the three different resolutions, highlighting the relative advantages and disadvantages of running ocean–sea ice models at higher resolution.
We find that higher resolution is an advantage in resolving flow through small straits, the structure of western boundary currents, and the abyssal overturning cell but that there is scope for improvements in sub-grid-scale parameterizations at the highest resolution.
The impact of topography on seismic amplification during the 2005 Kashmir earthquake
Authors: Khan Saad , van der Meijde Mark , van der Werff Harald , Shafique Muhammad
Published: February 2020

Abstract. Ground surface topography influences the spatial distribution of earthquake-induced ground shaking. This study shows the influence of topography on seismic amplification during the 2005 Kashmir earthquake. Earth surface topography scatters and reflects seismic waves, which causes spatial variation in seismic response. We performed a 3-D simulation of the 2005 Kashmir earthquake in Muzaffarabad with the spectral finite-element method. The moment tensor solution of the 2005 Kashmir earthquake was used as the seismic source. Our results showed amplification of seismic response on ridges and de-amplification in valleys. It was found that slopes facing away from the source received an amplified seismic response, and that 98 % of the highly damaged areas were located in the topographically amplified seismic response zone.
Monitoring soil salinity using time-lapse electromagnetic conductivity imaging
Authors: Paz Maria Catarina , Farzamian Mohammad , Paz Ana Marta , Castanheira Nádia Luísa , Gonçalves Maria Conceição , Monteiro Santos Fernando
Published: February 2020

Abstract. Lezíria Grande of Vila Franca de Xira, located in Portugal, is an important agricultural system where soil faces the risk of salinization, being thus prone to desertification and land abandonment. Soil salinity can be assessed over large areas by the following rationale: (1) use of electromagnetic induction (EMI) to measure the soil apparent electrical conductivity (ECa, dS m−1); (2) inversion of ECa to obtain electromagnetic conductivity images (EMCI) which provide the spatial distribution of the soil electrical conductivity (σ, mS m−1); (3) calibration process consisting of a regression between σ and the electrical conductivity of the saturated soil paste extract (ECe, dS m−1), used as a proxy for soil salinity; and (4) conversion of EMCI into salinity maps using the obtained calibration equation. In this study, EMI surveys and soil sampling were carried out between May 2017 and October 2018 at four locations with different salinity levels across the study area of Lezíria de Vila Franca. A previously developed regional calibration was used for predicting ECe from EMCI. This study aims to evaluate the potential of time-lapse EMCI and the regional calibration to predict the spatiotemporal variability of soil salinity in the study area. The results showed that ECe was satisfactorily predicted, with a root mean square error (RMSE) of 3.22 dS m−1 in a range of 52.35 dS m−1 and a coefficient of determination (R2) of 0.89. Results also showed strong concordance with a Lin’s concordance correlation coefficient (CCC) of 0.93, although, ECe was slightly overestimated with a mean error (ME) of −1.30 dS m−1. Soil salinity maps for each location revealed salinity fluctuations related to the input of salts and water either through irrigation, precipitation or groundwater level and salinity. Time-lapse EMCI has proven to be a valid methodology for evaluating the risk of soil salinization, and can further support the evaluation and adoption of proper agricultural management strategies, especially in irrigated areas, where continuous monitoring of soil salinity dynamics is required.
Effects of decimetre-scale surface roughness on L-band brightness temperature of sea ice
Authors: Miernecki Maciej , Kaleschke Lars , Maaß Nina , Hendricks Stefan , Søbjærg Sten Schmidl
Published: February 2020

Abstract. Sea ice thickness is an essential climate variable. Current L-Band sea ice thickness retrieval methods do not account for sea ice surface roughness that is hypothesised to be not relevant to the process. This study attempts to validate this hypothesis that has not been tested yet. To test this hypothesis, we created a physical model of sea ice roughness based on geometrical optics and merged it into the L-band emissivity model of sea ice that is similar to the one used in the operational sea ice thickness retrieval algorithm. The facet description of sea ice surface used in geometrical optics is derived from 2-D surface elevation measurements. Subsequently the new model was tested with TB measurements performed during the SMOSice 2014 field campaign. Our simulation results corroborate the hypothesis that sea ice surface roughness has a marginal impact on near-nadir TB (used in the current operational retrieval). We demonstrate that the probability distribution function of surface slopes can be approximated with a parametric function whose single parameter can be used to characterise the degree of roughness. Facet azimuth orientation is isotropic at scales greater than 4.3 km. The simulation results indicate that surface roughness is a minor factor in modelling the sea ice brightness temperature. The change in TB is most pronounced at incidence angles greater than 40∘ and can reach up to 8 K for vertical polarisation at 60∘. Therefore current and future L-band missions (SMOS, SMAP, CIMR, SMOS-HR) measuring at such angles can be affected. Comparison of the brightness temperature simulations with the SMOSice 2014 radiometer data does not yield definite results.
Sea ice volume variability and water temperature in the Greenland Sea
Authors: Selyuzhenok Valeria , Bashmachnikov Igor , Ricker Robert , Vesman Anna , Bobylev Leonid
Published: February 2020

Abstract. This study explores a link between the long-term variations in the integral sea ice volume (SIV) in the Greenland Sea and oceanic processes. Using the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS, 1979–2016), we show that the increasing sea ice volume flux through Fram Strait goes in parallel with a decrease in SIV in the Greenland Sea. The overall SIV loss in the Greenland Sea is 113 km3 per decade, while the total SIV import through Fram Strait increases by 115 km3 per decade. An analysis of the ocean temperature and the mixed-layer depth (MLD) over the climatic mean area of the winter marginal sea ice zone (MIZ) revealed a doubling of the amount of the upper-ocean heat content available for the sea ice melt from 1993 to 2016. This increase alone can explain the SIV loss in the Greenland Sea over the 24-year study period, even when accounting for the increasing SIV flux from the Arctic. The increase in the oceanic heat content is found to be linked to an increase in temperature of the Atlantic Water along the main currents of the Nordic Seas, following an increase in the oceanic heat flux from the subtropical North Atlantic. We argue that the predominantly positive winter North Atlantic Oscillation (NAO) index during the 4 most recent decades, together with an intensification of the deep convection in the Greenland Sea, is responsible for the intensification of the cyclonic circulation pattern in the Nordic Seas, which results in the observed long-term variations in the SIV.