bluuebunny/crossref_metadata_2025 huggingface dataset:
Lower Cretaceous Bullhead Group between Bullmoose Mountain and Tetsa River, Rocky Mountain Foothills, northeastern British Columbia
Authors: Stott D F
Published: January 2017

The Cadomin and Gething formations were studied in outcrop along the Foothills of northeastern British Columbia between latitude 55°N and 59°N. The study was supplemented by data from wells in the adjoining Plains.
The Bullhead Group represents the initial deposits of the early transgressive phase (late Neocomian/Aptian) of an advancing boreal sea which culminated in the widespread marine inundation of Albian time. The margins of the embayment essentially parallel the present structural trends of the Rocky
Mountains but a strong northeasterly element, related to the ancient Peace River Arch, produced a major deltaic complex in the vicinity of Peace River. The group attains a maximum thickness of 2,500 feet at Peace River and thins northeastward to a depositional edge.
The Bullhead Group is a deltaic wedge comprised dominantly of detritus derived from a source area lying west of the front ranges of the Rocky Mountains which was being elevated during the Columbian orogeny. A basal sequence of some 500 to 700 feet of chert conglomerate and conglomeratic sandstones
thins in a northeasterly direction and grades laterally into finer elastics. The overlying and, in part laterally equivalent, Gething Formation contains deltaic sediments at Peace River which interfinger northward with nearshore and shallow marine sandstones and shale which, in turn, grade into
marine shales and siltstones of the offshore environment.
The base of the group is marked by an erosional unconformity and underlying rocks, ranging in age from Valanginian (Early Cretaceous) to Triassic, are truncated in a northerly and northeasterly direction. Marine shales overlying the Bullhead Group are of early Albian age. The group contains the
"Lower Blairmore-Luscar" flora and a previously unreported marine microfauna of late Neocomian to early Albian age.
The Bullhead Group contains rocks from which petroleum and natural gas have been produced already. Potential reservoir rock occurs within a thick succession of Gething sandstones which extend beneath the Plains adjacent to the Foothills of British Columbia. Deposits of sub-bituminous to bituminous
coal occur within the Gething Formation between Smoky and Sikanni Chief rivers, and a large potential reserve is indicated.
Isotope hydrogeology and geothermometry of the Mount Meager geothermal area, final report, August 1980
Authors: Clark I D , Fritz P , Michel A
Published: January 2017

A substantial survey of stable and radioactive environmental isotopes has been carried out in order to investigate the recharge, thermal history, age and geothermometry of the thermal waters at Mount Meager, B.C., a Quaternary volcano currently the site of active
exploration for geothermal resources. Isotope determinations include 18 0, 2 H and 3H in precipitation, runoff waters, thermal and cold groundwaters and glacier ice, 13c and 14c in dissolved inorganic carbon and 180 and 34s in dissolved sulphate from thermal and cold groundwaters as well as 13c and
180 in hydrothermal calcite crystals. Major ion analyses were performed on thermal and cold spring waters. Precipitation and cold spring data have been used to define the local meteoric waterline and to document the altitude effect on waters recharging the geothermal system, demonstrating there to
be two hydrogeologically separate reservoirs which are recharged at different altitudes. Both pools of geothermal waters have experienced shifts of between +0.5 and +1.5 %0 in o1 8 0 values indicating a limited degree of 180 exchange with hot silicate minerals. Tritium contents indicate these
waters to have recharged prior to 1955. Carbon-13 contents in dissolved inorganic carbon and in hydrothermal calcites from drill core demonstrate there to be contamination of the thermal wate; s with "dead" volcanogenic co2 plus carbon exchange with ... fracture calcite which precludes the
possibility of dating the thermal waters using carbon-14. Several chemical and isotopic geothermometers are used to estimate the maximum temperatures experienced by the thermal waters. The fractionation of 180 between so 4 2- and H 2 o in these waters gives calculated maximum temperatures of less
than 140°C. The dissolved sulphate is shown to comprise inputs from oxidized volcanogenic H2s and so2 gases and from dissolution of marine sulphate in the metasedimentary basement rocks. The Mg-corrected Na-K-Ca geothermometer shows excellent correlation with the so 4 -H2o estimates with
maximum temperatures less than 120°c. Fractionation of 13c and 180 in the systems CaCO3-co2 and CaCO 3 -H 2 o using hydrothermal calcites and borehole fluids off er no indications of subsurface temperatures in excess of 140°C.Silica geothermometer results are not reliable due to
equilibrium with amorphous silica phases in the subsurface. The thermal waters are shown to have mixed with up to 15% cold groundwaters with apparently no substantial effect on the geothermometer estimates. It is concluded that these thermal waters are not deeply circulating and have not
experienced temperatures in excess of 140°C.
Regional hydrocarbon potential of the Labrador Shelf
Authors: Nantais P
Published: January 2017

The hydrocarbon potential of the Labrador Shelf has been evaluated sing source rock analyses and maturation indices· from 14 wells drilled between 1978 and 1983. This data supplements previous studies on 9 earlier wells. Using corrected subsurface
temperatures, an average geothermal gradient of 2.93° C/100m was calculated. The distribution of gradients does not dis­play any clear relationship to sediment thickness or basement structure. Wells drilled on the flank of basement highs may have enhanced geothermal gradients. This reflects the
proximity of these wells to faults penetrating to basement. The Cenozoic-Mesozoic sediments contain above average concentrations of organic carbon, however, it is predominantly terrestrially derived and thus gas prone. The concentration of heavy hydrocarbons in the sediments are generally below
required threshold values for significant oil generation. A few oil prone zones were encountered, but are thin and discontinuous. These suggest there is considerable variation in the source potential of the or­ganic matter on the Labrador Shelf. Tertiary sediments have reached full maturity in only
one well. Full maturity is attained at a depth of approximately 3000-3300m. Wells pene­trating thick Tertiary sections (>4km) are only marginally mature despite high subsurface temperatures (110-120° C). This reflects the effect of time on maturation. Consideration of recent
hydrocarbon generation models indi­cate the reservoired gas condensate on the Labrador Shelf is derived from predominantly Cretaceous sediments dominated by terrestrial organic matter in the marginally mature to mature zone.
Axial length, anterior chamber depth and lens thickness: Their intercorrelations in black South Africans
Authors: Mashige Khathutshelo P. , Oduntan Olalekan A.
Published: January 2017

Purpose: To determine means and ranges for axial length, anterior chamber depth, lens thickness values and their intercorrelations in an African population.Methods: Six hundred participants (N = 600) were selected through stratified random cluster sampling from geographically contiguous areas of Durban, South Africa. All participants underwent height measurements and standard vision testing. Repeated measures of axial length, anterior chamber depth and lens thickness were taken with the Nidek US-500 Echoscan.Results: Participants’ ages ranged from 10 to 66 years with a mean age of 28.15 ± 13.09 years (95% confidence interval, 27.09–29.19). Of all the subjects, 295 (49.17%) were females and 305 (50.83%) were males. Axial length ranged from 20.42 mm to 27.28 mm with a mean of 23.05 mm ± 0.98 mm (95% confidence interval, 22.97–23.14), anterior chamber depth ranged from 2.38 mm to 4.13 mm with a mean of 3.21 mm ± 0.37 mm (95% confidence interval, 3.18–3.24) and crystalline lens thicknesses ranged from 2.24 mm to 4.66 mm with a mean of 3.69 mm ± 0.25 mm (95% confidence interval, 3.66–3.71). All three biometric indices were significantly higher in men than in women (all p-values < 0.05). A multivariate linear regression model indicated that axial length and anterior chamber depth decreased with age, while lens thickness increased with age. All biometric indices directly correlated with the male gender and height (all p-values < 0.001). Pearson correlation coefficient tests showed that axial length was significantly positively correlated with anterior chamber (r = 0.66, p < 0.001) and negatively correlated with lens thickness (r = -0.52, p < 0.001). A significant negative correlation was found between lens thickness and anterior chamber depth values (r = -0.68, p < 0.001).Conclusion: Normative values for axial length, anterior chamber depth and lens thickness are determined for the first time in a black South African sample, aged 10–66 years. Age, gender and height were associated with biometric indices. While there was a positive correlation between axial length and anterior chamber depth, there was a negative correlation between lens thickness and both axial length and anterior chamber depth. These biometric data and their intercorrelations may provide some insights into the pathophysiological mechanisms of angle-closure glaucoma in this population.
Assessing social vulnerability to drought in South Africa: Policy implication for drought risk reduction
Authors: Muyambo Fumiso , Jordaan Andries J. , Bahta Yonas T.
Published: January 2017

The aim of this article was to assess and identify social vulnerability of communal farmers to drought in the O.R. Tambo district in the Eastern Cape province of South Africa using a survey data and social vulnerability index (SoVI). Eleven social vulnerability indicators were identified using Bogardi, Birkman and Cardona conceptual framework. The result found that an SoVI estimated for O.R. Tambo district was very high with a Likert scale of 5 for cultural values and practices, security or safety, social networks, social dependence, preparedness strategies and psychological stress attributed for the high value of social vulnerability to drought. Indigenous knowledge and education had an SoVI value of 2, which was of low vulnerability, contributing positively to resilience to drought. The study also found that government involvement in drought risk reduction is limited; as a result, the study recommends that a national, provincial and district municipalities policy on drought risk reduction and mitigation should be developed.
A successful story of translational orthodontic research: Micro-osteoperforation-from experiments to clinical practice
Authors: Chou Michelle Yuching , Alikhani Mani
Published: January 2017

The gap between basic science research and clinical application has long existed and therefore translational research has emerged in recent years to bridge such gap. Consortium for Translational Orthodontic Research (CTOR) was established with missions to integrate resources from different entities and to provide a platform for interdisciplinary groups who share the same vision to exchange ideas and inspire innovations. During its short existence, CTOR has successfully carried out several research projects which led to various innovations. Micro-osteoperforation is by far one of the most successful examples of translational research in the orthodontic field. It exemplifies how translational research can benefit scientists, clinicians, and patients. In this article, the process of its development, the rationale and scientific evidence from animal and clinical studies, and how it can be applied in daily practice will be depicted.
Clear retainer
Authors: Chaimongkol Priyakorn , Suntornlohanakul Supanee
Published: January 2017

A clear retainer is a removable retainer that is popular in the present day. Compared with conventional fixed and removable orthodontic retainers, it is a more esthetic, comfortable, and inexpensive appliance. Although several studies have been published about clear retainers, it could be difficult to interpret the results because of the variety of study designs, sample sizes, and research methods. This article is intended to compile the content from previous studies and discuss advantages, disadvantages, fabrication, insertion, and adjustment. Moreover, the effectiveness in maintaining dental position, occlusion, retention protocols, thickness, and survival rate of clear retainers is discussed.
Validity of mathematical proportions in maxillary anterior teeth among Bangladeshi population
Authors: Aziz Monwarul , Hossain Md. Zakir
Published: January 2017

Objective

To investigate the existence and suitability of mathematical proportions between the widths of maxillary anterior teeth in Bangladeshi population having an esthetic smile, with the aid of digital photographs and computer analysis.

Place of Study

The study was conducted at the Department of Orthodontics and Dentofacial Orthopedics of Dhaka Dental College and Hospital, Dhaka.

Period of Study

The study was conducted from April 2016 to September 2016.

Sample Selection

The study samples collected from Students of Dhaka Dental College, Mirpur-14, Dhaka, Bangladesh, with age limit 18–35 years.

Materials and Methods

Standardized frontal images of 100 dental students of Dhaka Dental College were captured. All the images were downloaded to a personal computer, and width of each tooth was measured by the scale tool of Photoshop CS version 8.0. All the data were analyzed (through standard statistical method) using Statistical Package for Social Science Software version 20 (IBM Corp., USA).

Results

The golden proportion existed in 17% of the perceived width ratios of lateral incisor to central incisor and 4% of the width ratios of canine to lateral incisor in natural dentition. Sixty-six percent lateral incisors are following the golden percentage, but only 7% central incisors and 21% canines are following the golden percentage. The recurring esthetic dental (RED) proportion existed in only 4% of participants.

Conclusions

The golden proportion, golden percentage, and the RED proportion cannot be used as constant proportions to create a harmonious proportion throughout the width of maxillary anterior teeth. The adjusted golden percentage might serve as a guideline to create harmonious proportions in maxillary anterior teeth for Bangladeshi population.
Clinical photography: A to Z
Authors: Nayak Arun
Published: January 2017

Clinical orthodontic photography is a vital skill set that every practicing orthodontist should master to be successful at the documentation of case records, patient education, peer presentations, marketing, and at acquiring additional certifications. This article aims to review various aspects of orthodontic photography and relevant research.
A new proof of the sharpness of the phase transition for Bernoulli percolation on $\mathbb Z^d$
Authors: Duminil-Copin Hugo , Tassion Vincent
Published: January 2017

We provide a new proof of the sharpness of the phase transition for nearest-neighbour Bernoulli percolation on

\mathbb Z^d

. More precisely, we show that

In [DCT], we give a more general proof which covers long-range Bernoulli percolation (and the Ising model) on arbitrary transitive graphs. This article presents the argument of [DCT] in the simpler framework of nearest-neighbour Bernoulli percolation on

\mathbb Z^d

.
New theoretical discourses in the discussion of the Neolithisation process in South Scandinavia during the late 5th and early 4th millennium BC – an identification of learning processes, communities of practise and migrations
Authors: Sørensen Lasse
Published: January 2017

In this paper, it is argued that agriculture is a very complex technology, which takes a long time to learn, thus making it very difficult for agrarian practises to spread as ideas. Instead, based on a detailed survey of primary agrarian evidence (direct 14C dates of cereals and domesticated animals) and secondary evidence of material culture (polished axes and pottery), it is claimed that the expansions of agrarian practises in South Scandinavia are associated with the migration of farmers who were related to the Michelsberg Culture. These incoming farmers had the appropriate skills and the ability to teach the indigenous hunter-gatherer populations about agriculture by establishing communities of practice, a fact which supports the theory of integrationism. The engagement in these communities of practise changed the identity and material culture of the immigrating farmers, as well as the indigenous hunter-gatherers, thus creating new agrarian societies in South Scandinavia which were interconnected in a regional as well as larger European network.
What is a lunar standstill III?
Authors: Sims Lionel Duke
Published: January 2017

Prehistoric monument alignments on lunar standstills are currently understood for horizon range, perturbation event, crossover event, eclipse prediction, solstice full Moon and the solarisation of the dark Moon. The first five models are found to fail the criteria of archaeoastronomy field methods. The final model of lunar-solar conflation draws upon all the observed components of lunar standstills – solarised reverse phased sidereal Moons culminating in solstice dark Moons in a roughly nine-year alternating cycle between major and minor standstills. This lunar-solar conflation model is a syncretic overlay upon an antecedent Palaeolithic template for lunar scheduled rituals and amenable to transformation.
Landscape construction and time reckoning in Iron Age Celtic Iberia
Authors: González-García A. César , García Quintela Marco V. , Belmonte Juan A.
Published: January 2017

In this paper, we report on three areas of the Iberian Peninsula that were occupied at least during the Iron Age and the early stages of Romanisation, where observations of astronomical phenomena in the landscape, rock carvings, and Latin inscriptions point to a particular method of time reckoning. All of these sites have previously been connected with the Celtic culture. The knowledge of the natural world that Classical sources assigned to these peoples need not have been reflected in a monolithic calendrical system used by all Celtic communities on the Continent. In fact, such a ‘Celtic calendar’ may have had different expressions in different areas, expressed in different ways, although sharing some common characteristics such as the particual use of the lunar and solar cycles.
Function and behaviour: use-wear evidence from Upper Paleolithic tools in southern Shanxi Province, North China
Authors: Chen Hong , Wang Yiren , Chen Chun
Published: January 2017

Lithic use-wear analysis has become a principal approach for interpreting the function of stone tools and inferring human behaviour. This study presents the results of use-wear analysis on lithic tools excavated from the Upper Paleolithic sites of Xiachuan and Chaisi in the southern part of Shanxi Province, North China. In this study, microblades and so-called core-like tools from these two sites were selected for examination by low-power techniques to identify their use patterns. The results suggest that approx. 30% of microblades might have been used mainly to process animal substances, and a lower percentage for vegetal substances. Based on the use-wear evidence, items classified as core-like tools should be regarded as microblade-cores, since they exhibit few traces of utilisation.
Neolithisation of technology: innovation and tradition in the Starčevo culture osseous industry
Authors: Vitezović Selena
Published: January 2017

The earliest Neolithic cultures in Southeast Europe brought significant changes in many aspects of everyday life, in subsistence, settlement patterns, architecture, and also ritual aspects. Technological changes are also very important – the introduction of completely new technologies, such as clay working, or new techniques in existing industries, e.g., lithic, osseous, etc. The osseous industry is especially informative for questions on innovations and traditions, since it was well developed in both the Mesolithic and Neolithic periods. In Starčevo culture, certain Mesolithic traditions may be observed, such as techniques for antler manufacture; however, numerous innovations are also visible, particularly techno-types of Near Eastern origin such as spatula-spoons, the most characteristic bone techno-type of the Early Neolithic in South-east Europe, as well as diverse decorative items. Furthermore, new raw materials (bones from domestic animals) are introduced, and new techniques for manufacture and new tools. It is also interesting to observe that, although osseous materials remain the dominant raw material for personal ornaments, they are no longer used for artistic expression.
Neolithisation of Sava-Drava-Danube interfluve at the end of the 6600–6000 BC period of Rapid Climate Chang: a new solution to an old problem
Authors: Botić Katarina
Published: January 2017

The idea of the Neolithisation of the Sava-Drava-Danube interfluve has undergone very little change since S. Dimitrijević's time. Despite their many shortcomings, new archaeological excavations and radiocarbon dates of Early Neolithic sites have provided us with new insight into the process of Neolihisation of this region. Using the recently published work by B. Weninger and L. Clare (Clare, Weninger 2010; Weninger et al. 2009; Weninger et al. 2014) as a starting point, the available radiocarbon and archaeological data are used to build up a time frame comparable to the wider region of Southeast Europe and climate conditions for specific period. The results fit the model of Neolithisation well (Weninger et al. 2014.9, Fig. 4), filling in the geographical gaps.
Time-varying changes in the simulated structure of the Brewer–Dobson Circulation
Authors: Garfinkel Chaim I. , Aquila Valentina , Waugh Darryn W. , Oman Luke D.
Published: January 2017

Abstract. A series of simulations using the NASA Goddard Earth Observing System Chemistry Climate Model are analyzed in order to assess changes in the Brewer–Dobson Circulation (BDC) over the past 55 years. When trends are computed over the past 55 years, the BDC accelerates throughout the stratosphere, consistent with previous modeling results. However, over the second half of the simulations (i.e., since the late 1980s), the model simulates structural changes in the BDC as the temporal evolution of the BDC varies between regions in the stratosphere. In the mid-stratosphere in the midlatitude Northern Hemisphere, the BDC does not accelerate in the ensemble mean of our simulations despite increases in greenhouse gas concentrations and warming sea surface temperatures, and it even decelerates in one ensemble member. This deceleration is reminiscent of changes inferred from satellite instruments and in situ measurements. In contrast, the BDC in the lower stratosphere continues to accelerate. The main forcing agents for the recent slowdown in the mid-stratosphere appear to be declining ozone-depleting substance (ODS) concentrations and the timing of volcanic eruptions. Changes in both mean age of air and the tropical upwelling of the residual circulation indicate a lack of recent acceleration. We therefore clarify that the statement that is often made that climate models simulate a decreasing age throughout the stratosphere only applies over long time periods and is not necessarily the case for the past 25 years, when most tracer measurements were taken.
Aerosol optical depth thresholds as a tool to assess diffuse radiation fertilization of the land carbon uptake in China
Authors: Yue Xu , Unger Nadine
Published: January 2017

Abstract. China suffers from frequent haze pollution episodes that alter the surface solar radiation and influence regional carbon uptake by the land biosphere. Here, we apply combined vegetation and radiation modeling and multiple observational datasets to assess the radiative effects of aerosol pollution in China on the regional land carbon uptake for the 2009–2011 period. First, we assess the inherent sensitivity of China's land biosphere to aerosol pollution by defining and calculating two thresholds of aerosol optical depth (AOD) at 550 nm, (i) AODt1, resulting in the maximum net primary productivity (NPP), and (ii) AODt2, such that if local AOD < AODt2, the aerosol diffuse fertilization effect (DFE) always promotes local NPP compared with aerosol-free conditions. Then, we apply the thresholds, satellite data, and interactive vegetation modeling to estimate current impacts of aerosol pollution on land ecosystems. In the northeast, observed AOD is 55 % lower than AODt1, indicating a strong aerosol DFE on local NPP. In the southeastern coastal regions, observed AOD is close to AODt1, suggesting that regional NPP is promoted by the current level of aerosol loading, but that further increases in AOD in this region will weaken the fertilization effects. The North China Plain experiences limited enhancement of NPP by aerosols because observed AOD is 77 % higher than AODt1 but 14 % lower than AODt2. Aerosols always inhibit regional NPP in the southwest because of the persistent high cloud coverage that already substantially reduces the total light availability there. Under clear-sky conditions, simulated NPP shows widespread increases of 20–60 % (35.0 ± 0.9 % on average) by aerosols. Under all-sky conditions, aerosol pollution has spatially contrasting opposite sign effects on NPP from −3 % to +6 % (1.6 ± 0.5 % on average), depending on the local AOD relative to the regional thresholds. Stringent aerosol pollution reductions motivated by public health concerns, especially in the North China Plain and the southwest, will help protect land ecosystem functioning in China and mitigate long-term global warming.
Qualitative and quantitative analysis of atmospheric organosulfates in Centreville, Alabama
Authors: Hettiyadura Anusha P. S. , Jayarathne Thilina , Baumann Karsten , Goldstein Allen H. , de Gouw Joost A. , Koss Abigail , Keutsch Frank N. , Skog Kate , Stone Elizabeth A.
Published: January 2017

Abstract. Organosulfates are components of secondary organic aerosols (SOA) that form from oxidation of volatile organic compounds (VOCs) in the presence of sulfate. In this study, the composition and abundance of organosulfates were determined in fine particulate matter (PM2.5) collected from Centreville, AL, during the Southern Oxidant and Aerosol Study (SOAS) in summer 2013. Six organosulfates were quantified using hydrophilic interaction liquid chromatography (HILIC) with triple quadrupole mass spectrometry (TQD) against authentic standards. Among these, the three most abundant species were glycolic acid sulfate (0.5–52.5 ng m−3), lactic acid sulfate (0.5–36.7 ng m−3), and hydroxyacetone sulfate (0.5–14.3 ng m−3). These three species were strongly inter-correlated, suggesting similar precursors and/or formation pathways. Further correlations with sulfate, isoprene, and isoprene oxidation products indicate important roles for these precursors in organosulfate formation in Centreville. Positive filter sampling artifacts associated with these organosulfates due to gas adsorption or reaction of gas phase precursors of organosulfates with sulfuric acid were assessed for a subset of samples and were less than 7.8 % of their PM2.5 concentrations. Together, the quantified organosulfates accounted for  <  0.3 % of organic carbon mass in PM2.5. To gain insights into other organosulfates in PM2.5 collected from Centreville, semi-quantitative analysis was employed by way of monitoring characteristic product ions of organosulfates (HSO4− at m∕z 97 and SO4− ⋅  at m∕z 96) and evaluating relative signal strength by HILIC–TQD. Molecular formulas of organosulfates were determined by high-resolution time-of-flight (TOF) mass spectrometry. The major organosulfate signal across all samples corresponded to 2-methyltetrol sulfates, which accounted for 42–62 % of the total bisulfate ion signal. Conversely, glycolic acid sulfate, the most abundant organosulfate quantified in this study, was 0.13–0.57 % of the total bisulfate ion signal. Precursors of m∕z 96 mainly consisted of nitro-oxy organosulfates. Organosulfates identified were mainly associated with biogenic VOC precursors, particularly isoprene and to a lesser extent monoterpenes and 2-methyl-3-buten-2-ol (MBO). While a small number of molecules dominated the total organosulfate signal, a large number of minor species were also present. This study provides insights into the major organosulfate species in the southeastern US, as measured by tandem mass spectrometry that should be targets for future standard development and quantitative analysis.
Nitro-polycyclic aromatic hydrocarbons – gas-particle partitioning, mass size distribution, and formation along transport in marine and continental background air
Authors: Lammel Gerhard , Mulder Marie D. , Shahpoury Pourya , Kukučka Petr , Lišková Hana , Přybilová Petra , Prokeš Roman , Wotawa Gerhard
Published: January 2017

Abstract. Nitro-polycyclic aromatic hydrocarbons (NPAH) are ubiquitous in polluted air but little is known about their abundance in background air. NPAHs were studied at one marine and one continental background site i.e., a coastal site in the southern Aegean Sea (summer 2012) and a site in the central Great Hungarian Plain (summer 2013), together with the parent compounds, PAHs. A Lagrangian particle dispersion model was used to track air mass history. Based on Lagrangian particle statistics, the urban influence on samples was quantified for the first time as a fractional dose to which the collected volume of air had been exposed to. At the remote marine site, the 3–4 ring nitro-PAH (sum of 11 targeted species, with 2-nitrofluoranthene (2NFLT) and 3-nitrophenanthrene being the most abundant) concentration was 23.7 pg m−3 while the concentration of 4-ring PAHs (6 species) was 426 pg m−3. Urban fractional doses in the range
Quantifying the global atmospheric power budget
Authors: Makarieva Anastassia M. , Gorshkov Victor G. , Nefiodov Andrei V. , Sheil Douglas , Nobre Antonio Donato , Li Bai-Lian
Published: January 2017

Abstract. The power of atmospheric circulation is a key measure of the Earth's climate system. The mismatch between predictions and observations under a warming climate calls for a reassessment of how atmospheric power W is defined, estimated and constrained. Here we review published formulations for W and show how they differ when applied to a moist atmosphere. Three factors, a non-zero source/sink in the continuity equation, the difference between velocities of gaseous air and condensate, and interaction between the gas and condensate modyfing the equations of motion, affect the formulation of W. Starting from the thermodynamic definition of mechanical work, we derive an expression for W from an explicit consideration of the equations of motion and continuity. Our analyses clarify how some past formulations are incomplete or invalid. Three caveats are identified. First, W critically depends on the boundary condition for gaseous air velocity at the Earth's surface. Second, confusion between gaseous air velocity and mean velocity of air and condensate in the expression for W results in gross errors despite the observed magnitudes of these velocities are very close. Third, W expressed in terms of measurable atmospheric parameters, air pressure and velocity, is scale-specific; this must be taken into account when adding contributions to W from different processes. We further present a formulation of the atmospheric power budget, which distinguishes three components of W: the kinetic power associated with horizontal pressure gradients (WK), the gravitational power of precipitation (WP) and the condensate loading (Wc). This formulation is valid with an accuracy of the squared ratio of the vertical to horizontal air velocities. Unlike previous approaches, it allows evaluation of WP + Wc without knowledge of atmospheric moisture or precipitation. This formulation also highlights that WP and Wc are the least certain terms in the power budget as they depend on vertical velocity; WK depending on horizontal velocity is more robust. We use MERRA and NCAR/NCEP re-analyses to evaluate the atmospheric power budget at different scales. Estimates of WK are found to be consistent across the re-analyses, while estimates for W and WP drastically differ. We then estimate independent precipitation-based values of WP and discuss how such estimates could reduce uncertainties. Our analyses indicate that WK increases with temporal resolution approaching our theoretical estimate for condensation-induced circulation when all convective motion is resolved. Implications of these findings for constraining global atmospheric power are discussed.
Speciation of anthropogenic emissions of non-methane volatile organic compounds: a global gridded data set for 1970–2012
Authors: Huang Ganlin , Brook Rosie , Crippa Monica , Janssens-Maenhout Greet , Schieberle Christian , Dore Chris , Guizzardi Diego , Muntean Marilena , Schaaf Edwin , Friedrich Rainer
Published: January 2017

Abstract. Non-methane volatile organic compounds (NMVOC) include a large number of chemical species which differ significantly in their chemical characteristics and thus in their impacts on ozone and secondary organic aerosols formation. It is important that chemical transport models (CTMs) simulate the chemical transformation of the different NMVOC species in the troposphere consistently. In most emission inventories, however, only total NMVOC emissions are reported, which need to be decomposed into classes to fit the requirements of CTMs. For instance, the Emissions Database for Global Atmospheric Research (EDGAR) provides spatially resolved global anthropogenic emissions of total NMVOC. In this study the EDGAR NMVOC inventory was revised and extended in time and in sectors. Moreover the new version of NMVOC emission data in the EDGAR database were disaggregated on a high sector resolution to individual species or species groups, thus enhancing the usability of the NMVOC emission data by the modelling community. Region- and source-specific speciation profiles of NMVOC species or species groups, are compiled and mapped to EDGAR processes (high resolution of sectors), with corresponding quality codes specifying the quality of the mapping. Individual NMVOC species in different profiles are aggregated to 25 species groups, in line with the common classification of the Global Emissions Initiative (GEIA). Global annual grid maps with a resolution of 0.1° × 0.1° for the period 1970–2012 are produced by sector and species. Furthermore, trends of NMVOC composition are analysed taking road transport and residential sources in Germany and the United Kingdom (UK) as examples.
Understanding the variability of magnetic storms caused by ICMEs
Authors: Benacquista Remi , Rochel Sandrine , Rolland Guy
Published: January 2017

Abstract. In this paper, we study the dynamics of magnetic storms due to interplanetary coronal mass ejections (ICMEs). We used multi-epoch superposed epoch analyses (SEAs) with a choice of epoch times based on the structure of the events. By sorting the events with respect to simple large-scale features (presence of a shock, magnetic structure, polarity of magnetic clouds), this method provides an original insight into understanding the variability of magnetic storm dynamics. Our results show the necessity of seeing ICMEs and their preceding sheaths as a whole since each substructure impacts the other and has an effect on its geoeffectiveness. It is shown that the presence of a shock drives the geoeffectiveness of the sheaths, while both the shock and the magnetic structure impact the geoeffectiveness of the ICMEs. In addition, we showed that the ambient solar wind characteristics are not the same for ejecta and magnetic clouds (MCs). The ambient solar wind upstream magnetic clouds are quieter than upstream ejecta and particularly slower. We also focused on the polarity of magnetic clouds since it drives not only their geoeffectiveness but also their temporal dynamics. South–north magnetic clouds (SN-MCs) and north–south magnetic clouds (NS-MCs) show no difference in geoeffectiveness for our sample of events. Lastly, since it is well-known that sequences of events can possibly induce strong magnetic storms, such sequences have been studied using superposed epoch analysis (SEA) for the first time. We found that these sequences of ICMEs are very usual and concern about 40 % of the ICMEs. Furthermore, they cause much more intense magnetic storms than isolated events do.
Leaf nitrogen from first principles: field evidence for adaptive variation with climate
Authors: Dong Ning , Prentice Iain Colin , Evans Bradley J. , Caddy-Retalic Stefan , Lowe Andrew J. , Wright Ian J.
Published: January 2017

Abstract. Nitrogen content per unit leaf area (Narea) is a key variable in plant functional ecology and biogeochemistry. Narea comprises a structural component, which scales with leaf mass per area (LMA), and a metabolic component, which scales with Rubisco capacity. The co-ordination hypothesis, as implemented in LPJ and related global vegetation models, predicts that Rubisco capacity should be directly proportional to irradiance but should decrease with increases in ci : ca and temperature because the amount of Rubisco required to achieve a given assimilation rate declines with increases in both. We tested these predictions using LMA, leaf δ13C, and leaf N measurements on complete species assemblages sampled at sites on a north–south transect from tropical to temperate Australia. Partial effects of mean canopy irradiance, mean annual temperature, and ci : ca (from δ13C) on Narea were all significant and their directions and magnitudes were in line with predictions. Over 80 % of the variance in community-mean (ln) Narea was accounted for by these predictors plus LMA. Moreover, Narea could be decomposed into two components, one proportional to LMA (slightly steeper in N-fixers), and the other to Rubisco capacity as predicted by the co-ordination hypothesis. Trait gradient analysis revealed ci : ca to be perfectly plastic, while species turnover contributed about half the variation in LMA and Narea. Interest has surged in methods to predict continuous leaf-trait variation from environmental factors, in order to improve ecosystem models. Coupled carbon–nitrogen models require a method to predict Narea that is more realistic than the widespread assumptions that Narea is proportional to photosynthetic capacity, and/or that Narea (and photosynthetic capacity) are determined by N supply from the soil. Our results indicate that Narea has a useful degree of predictability, from a combination of LMA and ci : ca – themselves in part environmentally determined – with Rubisco activity, as predicted from local growing conditions. This finding is consistent with a plant-centred approach to modelling, emphasizing the adaptive regulation of traits. Models that account for biodiversity will also need to partition community-level trait variation into components due to phenotypic plasticity and/or genotypic differentiation within species vs. progressive species replacement, along environmental gradients. Our analysis suggests that variation in Narea is about evenly split between these two modes.
CFD simulations to optimize the blades design of water wheels
Authors: Quaranta Emanuele , Revelli Roberto
Published: January 2017

Abstract. In low head sites and at low discharges, water wheels can be considered among the most convenient hydropower converters to install. The scope of this work is to improve the performance of an existing breastshot water wheel changing the blades shape, using Computational Fluid Dynamic (CFD) simulations. Three optimal profiles are investigated: the profile of the existing blades, a circular profile and an elliptical profile. The results are validated performing experimental tests on the wheel with the existing profile. The numerical results show that the efficiency of breastshot wheels is affected by the blades profile. The average increase in efficiency using the new circular profile is about 4 % with respect to the profile of the existing blades.
Soilscape evolution of aeolian-dominated hillslopes during the Holocene: investigation of sediment transport mechanisms and climatic–anthropogenic drivers
Authors: Cohen Sagy , Svoray Tal , Sela Shai , Hancock Greg , Willgoose Garry
Published: January 2017

Abstract. Here we study the soilscape (soil-landscape) evolution of a field site in the semiarid zone of Israel. This region, like similar regions around the world, was subject to intensive loess accumulation during the Pleistocene and early Holocene. Today, hillslopes in this region are dominated by exposed bedrock with deep loess depositions in the valleys and floodplains. The drivers and mechanism that led to this soilscape are unclear. Within this context, we use a soilscape evolution model (mARM5D) to study the potential mechanisms that led to this soilscape. We focus on advancing our conceptual understanding of the processes at the core of this soilscape evolution by studying the effects of fluvial and diffusive sediment transport mechanisms, and the potential effects of climatic and anthropogenic drivers. Our results show that, in our field site, dominated by aeolian soil development, hillslope fluvial sediment transport (e.g., surface wash and gullies) led to downslope thinning in soil, while diffusive transport (e.g., soil creep) led to deeper and more localized soil features at the lower sections of the hillslopes. The results suggest that, in this semiarid, aeolian-dominated and soil-depleted landscape, the top section of the hillslopes is dominated by diffusive transport and the bottom by fluvial transport. Temporal variability in environmental drivers had a considerable effect on soilscape evolution. Short but intensive changes during the late Holocene, imitating anthropogenic land use alterations, rapidly changed the site's soil distribution. This leads us to assume that this region's soil-depleted hillslopes are, at least in part, the result of anthropogenic drivers.
Steady state, erosional continuity, and the topography of landscapes developed in layered rocks
Authors: Perne Matija , Covington Matthew D. , Thaler Evan A. , Myre Joseph M.
Published: January 2017

Abstract. The concept of topographic steady state has substantially informed our understanding of the relationships between landscapes, tectonics, climate, and lithology. In topographic steady state, erosion rates are equal everywhere, and steepness adjusts to enable equal erosion rates in rocks of different strengths. This conceptual model makes an implicit assumption of vertical contacts between different rock types. Here we hypothesize that landscapes in layered rocks will be driven toward a state of erosional continuity, where retreat rates on either side of a contact are equal in a direction parallel to the contact rather than in the vertical direction. For vertical contacts, erosional continuity is the same as topographic steady state, whereas for horizontal contacts it is equivalent to equal rates of horizontal retreat on either side of a rock contact. Using analytical solutions and numerical simulations, we show that erosional continuity predicts the form of flux steady-state landscapes that develop in simulations with horizontally layered rocks. For stream power erosion, the nature of continuity steady state depends on the exponent, n, in the erosion model. For n = 1, the landscape cannot maintain continuity. For cases where n ≠ 1, continuity is maintained, and steepness is a function of erodibility that is predicted by the theory. The landscape in continuity steady state can be quite different from that predicted by topographic steady state. For n < 1 continuity predicts that channels incising subhorizontal layers will be steeper in the weaker rock layers. For subhorizontal layered rocks with different erodibilities, continuity also predicts larger slope contrasts than in topographic steady state. Therefore, the relationship between steepness and erodibility within a sequence of layered rocks is a function of contact dip. For the subhorizontal limit, the history of layers exposed at base level also influences the steepness–erodibility relationship. If uplift rate is constant, continuity steady state is perturbed near base level, but these perturbations decay rapidly if there is a substantial contrast in erodibility. Though examples explored here utilize the stream power erosion model, continuity steady state provides a general mathematical tool that may also be useful to understand landscapes that develop by other erosion processes.
Public Perceptions of a Rip Current Hazard Education Program: Break the Grip of the Rip!
Authors: Houser Chris , Trimble Sarah , Brander Robert , Brewster B. Chris , Dusek Greg , Jones Deborah , Kuhn John
Published: January 2017

Abstract. Rip currents pose a major global beach hazard; estimates of annual rip current related deaths in the United States alone range from 35 to 100 per year. Despite increased social research into beach-goer experience, little is known about levels of rip current knowledge within the general population. This study describes results of an online survey to determine the extent of rip current knowledge across the United States, with the aim of improving and enhancing existing beach safety education material. Results suggest that the Break the Grip of the Rip® campaign has been successful in educating the public about rip current safety directly or indirectly, with the majority of respondents able to provide an accurate description of how to escape a rip current. However, the success of the campaign is limited by discrepancies between personal observations at the beach and rip forecasts that are broadcasted for a large area and time. It was the infrequent beach user that identified the largest discrepancies between the forecast and their observations. Since infrequent beach users also do not seek out lifeguards or take the same precautions as frequent beach users, it is argued that they are also at greatest risk of being caught in a dangerous situation. Results of this study suggest a need for the national campaign to provide greater focus on locally specific and verified rip forecasts and signage in coordination with lifeguards, but not at the expense of the successful national awareness program.
The past, present, and future viscous heat dissipation available for Greenland subglacial conduit formation
Authors: Mankoff Kenneth D. , Tulaczyk Slawek M.
Published: January 2017

Abstract. Basal hydrology of the Greenland Ice Sheet (GIS) influences its dynamics and mass balance through basal lubrication and ice–bed decoupling or efficient water removal and ice–bed coupling. Variations in subglacial water pressure through the seasonal evolution of the subglacial hydrological system help control ice velocity. Near the ice sheet margin, large basal conduits are melted by the viscous heat dissipation (VHD) from surface runoff routed to the bed. These conduits may lead to efficient drainage systems that lower subglacial water pressure, increase basal effective stress, and reduce ice velocity. In this study we quantify the energy available for VHD historically at present and under future climate scenarios. At present, 345 km3 of annual runoff delivers 66 GW to the base of the ice sheet per year. These values are already ∼ 50 % more than the historical 1960–1999 value of 46 GW. By 2100 under IPCC AR5 RCP8.5 (RCP4.5) scenarios, 1278 (524) km3 of runoff may deliver 310 (110) GW to the ice sheet base. Hence, the ice sheet may experience a 5-to-7-fold increase in VHD in the near future which will enhance opening of subglacial conduits near the margin and will warm basal ice in the interior. The other significant basal heat source is geothermal heat flux (GHF), which has an estimated value of 36 GW within the present-day VHD area. With increasing surface meltwater penetration to the bed the basal heat budget in the active basal hydrology zone of the GIS will be increasingly dominated by VHD and relatively less sensitive to GHF, which may result in spatial changes in the ice flow field and in its seasonal variability.