bluuebunny/crossref_metadata_2025 huggingface dataset:
La conservation des parcs nationaux au-delà de leurs frontières
Authors: Deshaies Marie-Ève , Charest René
Published: December 2017

Le réseau des parcs nationaux du Québec vise à assurer la conservation et la protection permanente de territoires représentatifs des régions naturelles du Québec ou de sites naturels exceptionnels. Cependant, dans certains parcs, principalement ceux au sud du 50e parallèle, il peut s’avérer ardu de répondre aux besoins des espèces à grand domaine vital en raison des superficies variables des parcs. De plus, l’utilisation ou la dégradation du territoire en périphérie de ces parcs peut contribuer à une perte de leur valeur écologique. Afin de favoriser la mise en oeuvre de la mission de conservation des parcs nationaux, la Société des établissements de plein air du Québec (Sépaq) a entrepris de mobiliser les acteurs dans les territoires périphériques des parcs. Elle s’est fixé pour objectifs de caractériser les zones périphériques, de tenir des journées de réflexion rassemblant les acteurs locaux et régionaux et de mobiliser ces derniers afin qu’ils réalisent des actions concrètes pour mieux conserver ces territoires. Le maintien des richesses écologiques des parcs repose, en partie, sur l’engagement des acteurs à participer aux efforts de conservation en périphérie des parcs afin de réduire les effets des activités humaines sur les territoires protégés et assurer le maintien des services écologiques essentiels.
Extension du territoire connu de la fourmi Myrmica lampra au Québec (Formicides, Hyménoptères)
Authors: Francoeur André , Bouchard Mathieu
Published: December 2017

Lors d’un projet de recherche en foresterie, une gyne (reine) de la fourmi parasite Myrmica lampra a été capturée dans la région du Lac-Saint-Jean, au Québec. Cette découverte agrandit le territoire connu de cette espèce, rarement observée jusqu’à présent.
Les variations de niveau du lac Saint-Jean : effets sur la reproduction des poissons dans les habitats en milieux humides riverains
Authors: Plourde-Lavoie Patrick , Archer Marc , Gagnon Karine , Sirois Pascal
Published: December 2017

Le lac Saint-Jean a vu son régime hydrologique considérablement modifié depuis sa transformation en réservoir en 1926. Cet article examine les effets de la gestion du niveau du lac pour la fraie de la perchaude (Perca flavescens) et du grand brochet (Esox lucius). Une analyse des niveaux des eaux des 100 dernières années a permis de mettre en évidence une réduction des écarts entre les niveaux printaniers et estivaux, qui contribue vraisemblablement à diminuer la taille et la qualité des sites de reproduction, et un retardement de l’atteinte du niveau maximal au printemps par rapport au régime naturel. L’utilisation de données historiques de températures du lac et des milieux humides riverains a permis d’estimer les périodes de fraie de 1991 à 2015 et de mettre en évidence les conséquences des bas niveaux au printemps sur l’accessibilité des milieux humides. À présent, ces habitats ne sont généralement que partiellement inondés lors de la fraie des 2 espèces. Nous recommandons d’adopter une gestion du lac Saint-Jean qui vise à devancer l’atteinte des hauts niveaux printaniers et à maximiser les écarts entre les niveaux printaniers et estivaux, tout en maintenant un niveau stable au printemps pour permettre l’éclosion des oeufs de poissons et assurer la survie des jeunes stades de vie.
Effets du réseau routier sur la connectivité des frayères du grand brochet (Esox lucius) au lac Saint-Pierre (fleuve Saint-Laurent, Canada)
Authors: Le Pichon Céline , Mingelbier Marc , Legros Maëlle , Foubert Aline , Brodeur Philippe
Published: December 2017

Afin de compléter le portrait des pressions agissant sur les habitats aquatiques de la plaine d’inondation du lac Saint-Pierre, une analyse géomatique avancée évalue les effets du réseau routier sur la connectivité des frayères et des nourriceries du grand brochet (Esox lucius). Les résultats révèlent des effets négatifs sur les habitats à fort potentiel lorsque le débit à Sorel dépasse 12 000 m3.s−1 (récurrence : de 1 à 2 ans), créant des pertes directes au niveau des emprises (maximum : 142 ha) et de la fragmentation entre les habitats situés de part et d’autre des routes (maximum : 39 ha). Ces effets, principalement circonscrits dans la région nord-ouest du lac, dépendent largement des conditions hydrologiques entre la période de fraie et la première semaine de vie des larves. Les mesures de connectivité soulignent l’importance des ponceaux fonctionnels et du réseau hydrographique de la zone littorale, éléments essentiels à l’interconnexion des habitats. Il apparaît que les répercussions du réseau routier, bien qu’elles soient moindres que celles provoquées par les pratiques agricoles intensives ou encore par la régularisation du débit, demeurent non négligeables. La présente étude identifie les habitats à fort potentiel et des corridors de connectivité constituant des milieux prioritaires à protéger ou à restaurer.
Géopolitique de l’Ukraine
Authors: Lahille Éric
Published: December 2017

L’article questionne la pertinence heuristique des approches géopolitiques occidentales dominantes de la crise ukrainienne au regard de leurs fondements épistémologiques. Dérivés de paradigmes de Relations internationales controversés, les discours aujourd’hui les plus influents, d’essence culturaliste, peinent à dépasser les biais méthodologiques et les limites des approches idéalistes, étatistes ou néo-réalistes. L’essai de déconstruction des différentes modélisations met en évidence une même conception ethnocentriste et normative de l’ordre mondial servant de substrat à une véritable « convention hégémoniste ». Mais cette vision des relations internationales, organisée autour du présupposé de la prééminence états-unienne, ne permet pas de penser la complexité d’un conflit qui ne se réduit ni à l’impérialisme séculaire russe ni au simple retour de la guerre froide.
Le traité de Lisbonne et le droit international de l’investissement
Authors: Beaumier Guillaume
Published: December 2017

Le droit international des investissements a connu une évolution exponentielle au cours des deux dernières décennies. Avec plus de 3 000 accords et une abondante jurisprudence, certains qualifient ce système de chaotique et d’instable. Les divergences entre traités bilatéraux d’investissement et les décisions contraires de tribunaux arbitraux donnent certes cette impression. Cet article sur le développement du modèle de négociation de la Commission européenne, après l’entrée en vigueur du traité de Lisbonne, montre néanmoins que, tout en étant un système décentralisé et flexible, le régime des investissements est en réalité dynamiquement stable et favorise une répétition des normes préexistantes. Le chapitre sur l’investissement du récent Accord économique et commercial global (aecg) montre en effet que, tout en ayant eu l’occasion d’innover, la Commission européenne s’est largement inspirée du complexe institutionnel en place, y compris notamment, mais pas uniquement, le modèle d’accord des États-Unis.
La multipolarité et sa tournure « revanchiste » dans la politique internationale de la Russie : ses causes, son cheminement et les options du Canada
Authors: Lévesque Jacques , Breault Yann
Published: December 2017

Cet essai vise à montrer et expliquer comment le cheminement et le positionnement de la Russie sur la scène internationale ont pu aboutir, avec l’annexion de la Crimée et la guerre du Donbass, à une dégradation sans précédent des ses relations avec le monde occidental depuis la fin de la guerre froide. Il montre comment dès 1996, le processus d’élargissement de l’Otan a fait de la multipolarité le premier objectif de sa politique extérieure pour devenir ensuite le principal facteur récurent parmi ceux qui ont conduit à la situation actuelle. Il met aussi en relief et en comparaison les choix faits dans ce contexte par les deux gouvernements du Canada qui se sont succédé depuis la crise. Il montre comment et dans quelle mesure les prises de position et options du gouvernement actuel peuvent être tributaires du passé des relations du Canada avec la Russie.
An Aedes aegypti-associated fungus increases susceptibility to dengue virus by modulating gut trypsin activity
Authors: Angleró-Rodríguez Yesseinia I , Talyuli Octavio AC , Blumberg Benjamin J , Kang Seokyoung , Demby Celia , Shields Alicia , Carlson Jenny , Jupatanakul Natapong , Dimopoulos George
Published: December 2017

Transmission of dengue virus (DENV) requires successful completion of the infection cycle in the Aedes aegypti vector, which is initiated in the midgut tissue after ingestion of an infectious blood meal. While certain Ae. aegypti midgut-associated bacteria influence virus infection, little is known about the midgut-associated fungi (mycobiota), and how its members might influence susceptibility to DENV infection. We show that a Talaromyces (Tsp_PR) fungus, isolated from field-caught Ae. aegypti, render the mosquito more permissive to DENV infection. This modulation is attributed to a profound down-regulation of digestive enzyme genes and trypsin activity, upon exposure to Tsp_PR-secreted factors. In conclusion, we show for the first time that a natural mosquito gut-associated fungus can alter Ae. aegypti physiology in a way that facilitates pathogen infection.
Deciphering caveolar functions by syndapin III KO-mediated impairment of caveolar invagination
Authors: Seemann Eric , Sun Minxuan , Krueger Sarah , Tröger Jessica , Hou Wenya , Haag Natja , Schüler Susann , Westermann Martin , Huebner Christian A , Romeike Bernd , Kessels Michael M , Qualmann Britta
Published: December 2017

Several human diseases are associated with a lack of caveolae. Yet, the functions of caveolae and the molecular mechanisms critical for shaping them still are debated. We show that muscle cells of syndapin III KO mice show severe reductions of caveolae reminiscent of human caveolinopathies. Yet, different from other mouse models, the levels of the plasma membrane-associated caveolar coat proteins caveolin3 and cavin1 were both not reduced upon syndapin III KO. This allowed for dissecting bona fide caveolar functions from those supported by mere caveolin presence and also demonstrated that neither caveolin3 nor caveolin3 and cavin1 are sufficient to form caveolae. The membrane-shaping protein syndapin III is crucial for caveolar invagination and KO rendered the cells sensitive to membrane tensions. Consistent with this physiological role of caveolae in counterpoising membrane tensions, syndapin III KO skeletal muscles showed pathological parameters upon physical exercise that are also found in CAVEOLIN3 mutation-associated muscle diseases.
Hedgehog signaling via Gli2 prevents obesity induced by high-fat diet in adult mice
Authors: Shi Yu , Long Fanxin
Published: December 2017

Obesity poses a significant risk of developing type II diabetes and other diseases. Hedgehog (Hh) signaling has been shown to inhibit adipose tissue development, but its effect on diet-induced obesity during postnatal life is not known. Here by inducing expression of constitutively active Smoothened (SmoM2) or Gli2 (ΔNGli2) in the adipocyte lineage of postnatal mice, we show that targeted activation of Hh signaling suppresses high-fat-diet-induced obesity and improves whole-body glucose tolerance and insulin sensitivity. Both SmoM2 and ΔNGli2 induce the expression of Wnt6, a known anti-adipogenic factor, in fat depots of the mouse. Hh-Gli2 signaling inhibits not only adipocyte differentiation but also lipogenesis in adipocytes in vitro. Finally, pharmacological inhibition of Porcupine, an acyltransferase essential for Wnt secretion, alleviates both anti-adipogenic and anti-lipogenic effects of Hh in cell culture models. Overall, targeted activation of Hh signaling ameliorates diet-induced obesity and may be explored for pharmaceutical development.
A population of innate myelolymphoblastoid effector cell expanded by inactivation of mTOR complex 1 in mice
Authors: Tang Fei , Zhang Peng , Ye Peiying , Lazarski Christopher A , Wu Qi , Bergin Ingrid L , Bender Timothy P , Hall Michael N , Cui Ya , Zhang Liguo , Jiang Taijiao , Liu Yang , Zheng Pan
Published: December 2017

Adaptive autoimmunity is restrained by controlling population sizes and pathogenicity of harmful clones, while innate destruction is controlled at effector phase. We report here that deletion of Rptor in mouse hematopoietic stem/progenitor cells causes self-destructive innate immunity by massively increasing the population of previously uncharacterized innate myelolymphoblastoid effector cells (IMLECs). Mouse IMLECs are CD3-B220-NK1.1-Ter119- CD11clow/-CD115-F4/80low/-Gr-1- CD11b+, but surprisingly express high levels of PD-L1. Although they morphologically resemble lymphocytes and actively produce transcripts from Immunoglobulin loci, IMLECs have non-rearranged Ig loci, are phenotypically distinguishable from all known lymphocytes, and have a gene signature that bridges lymphoid and myeloid leukocytes. Rptor deletion unleashes differentiation of IMLECs from common myeloid progenitor cells by reducing expression of Myb. Importantly, IMLECs broadly overexpress pattern-recognition receptors and their expansion causes systemic inflammation in response to Toll-like receptor ligands in mice. Our data unveil a novel leukocyte population and an unrecognized role of Raptor/mTORC1 in innate immune tolerance.
Branching into brains
Authors: Shai Adam , Larkum Matthew Evan
Published: December 2017

What can artificial intelligence learn from neuroscience, and vice versa?
Neither slim nor fat: estimating the mass of the dodo (Raphus cucullatus, Aves, Columbiformes) based on the largest sample of dodo bones to date
Authors: van Heteren Anneke H. , van Dierendonk Roland C.H. , van Egmond Maria A.N.E. , ten Hagen Sjang L. , Kreuning Jippe
Published: December 2017

The dodo (Raphus cucullatus) might be the most enigmatic bird of all times. It is, therefore, highly remarkable that no consensus has yet been reached on its body mass; previous scientific estimates of its mass vary by more than 100%. Until now, the vast amount of bones stored at the Natural History Museum in Mauritius has not yet been studied morphometrically nor in relation to body mass. Here, a new estimate of the dodo’s mass is presented based on the largest sample of dodo femora ever measured (n= 174). In order to do this, we have used the regression method and chosen our variables based on biological, mathematical and physical arguments. The results indicate that the mean mass of the dodo was circa 12 kg, which is approximately five times as heavy as the largest living Columbidae (pigeons and doves), the clade to which the dodo belongs.
Identification and antioxidant activity of carotenoids from superfine powder of Rhodobacter sphaeroides
Authors: Li Zuming , Kong Lina , Hui Bodi , Shang Xiaoya , Gao Liping , Luan Na , Zhuang Xuliang , Wang Dong , Bai Zhihui
Published: December 2017

The interest in carotenoids from the natural-antioxidant point of view has recently risen sharply because of their substantial health benefits. Here, we report the identification and antioxidant activity of carotenoids extracted by superfine grinding from Rhodobacter sphaeroides 3757 which is a species of photosynthetic bacteria. After separation and purification by silica gel column chromatography and reversed-phase high performance liquid chromatography (RP-HPLC), the four major carotenoids from the superfine powder of R. sphaeroide 3757 were identified as bixin, hydroxyspheroidenone, 3,3¢,4¢-tetrahydrospirilloxanthin-20-al, and spheroidenone by reversed phase - high performance liquid chromatography - atmospheric pressure chemical ionization - mass spectrometry (RP-HPLC-APCI-MS). The antioxidant activity of the carotenoids extracted after superfine grinding of dry biomass of R. sphaeroide 3757 was higher than that after ultrasonic treatment. When the ratio solvent-to-solid was 30, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity, reducing power, and lipid peroxidation inhibitory activity of the extracts after superfine grinding were 74.0% ± 3.1%, 0.497 ± 0.022, and 77.6% ± 3.2%, respectively. By contrast, the extracts after ultrasonic treatment, these numbers were 61.0% ± 2.5%, 0.328 ± 0.014, and 55.2% ± 2.3%, respectively. These results indicate that carotenoids from R. sphaeroide 3757 show a significant antioxidant activity in vitro in a concentration-dependent manner, and that superfine grinding is the optimal extraction method. We hope to provide scientific guidance for commercial production of natural- antioxidant and functional food from carotenoids of R. sphaeroide.
Toxicologic evaluation of chronic feeding of glyphosate-resistant transgenic soybean GTS40-3-2 meal to rats
Authors: Yuan Jianqin , Tang Zhongwei , Zhao Jianghe , Shi Zongyong , Wang Jundong
Published: December 2017

To assess the safety of glyphosate-resistant transgenic soybean, the transgenic soybean GTS40-3-2 meal and its non-transgenic counterpart parent A5403 were fed to first- and second-generation Sprague-Dawley (SD) rats (Rattus norvegicus) for 195 days. The soybean meal made up 20% of the total weight of the feed. Body weight, food consumption, hematology, blood biochemistry, and pathological observations were monitored weekly. The results showed that rats of each group experienced good growth and development, and although results of some organ weight ratios and serum biochemistry between the groups were significantly different (P<0.05), they were of no biological significance because the variations were within the normal range. These results indicate that glyphosate-resistant transgenic soybean GTS40-3-2 meal is as safe as its non-transgenic parent soybean A5403 in a long-term SD rat feeding study. The study provides experimental evidence for the safe usage of transgenic soybean GTS40-3-2.
Effect of irrigation frequency on growth and production of a cucumber crop under soilless culture
Authors: Nikolaou Georgios , Neocleous Damianos , Katsoulas Nikolaos , Kittas Constantinos
Published: December 2017

Three irrigation frequencies were applied on a soilless cucumber crop, in a greenhouse located in the coastal area of southern Cyprus. Irrigation scheduling was based on solar radiation and performed whenever accumulated solar radiation energy outside the greenhouse reached 1.3 MJ m-2 [High Irrigation Frequency (HIF)], 1.9 MJ m-2 [Medium Irrigation Frequency (MIF)] and 3.0 MJ m-2 [Low Irrigation Frequency (LIF)]. The amount of water applied was 0.192 Kg m-2, 0.288 Kg m-2 and 0.448 Kg m-2 for high, medium and low irrigation frequencies, respectively. Appropriately, the total volume of water applied was identical in each of the three cases.  In order to study the effects of irrigation frequency on cucumber crops, multiple measurements were taken; the  fresh and dry weight of plant organs (i.e. leaves, stem and fruit), marketable fresh yield production, and microclimate variables for a 75 day period, beginning in April and ending in June. The results revealed that the irrigation frequency did not influence the cucumber crop’s growth and production. Plants at LIF were facing water stress conditions, as estimated from leaf temperature and stem micro variation measurements. However, HIF increased the transpiration rate of the plants, resulting in less water and nutrient losses.
Pathogenicity and rDNA-ITS sequence analysis of the Corynespora cassiicola isolates from rubber plantations in Indonesia
Authors: Oktavia Fetrina , . Kuswanhadi , . Widodo , Dinarti Diny , . Sudarsono
Published: December 2017

Corynespora cassiicola is an important pathogen causing Corynespora leaf fall disease on the rubber tree. Analysis of virulence, rDNA-ITS sequence and identification of cas gene were undertaken to investigate the effect of agro-climatic conditions and host rubber clones to virulence of 23 C. cassiicola isolates on six clones (RRIC 100, BPM 24, BPM 1, PB 260, GT 1 and RRIM 600) and to observed the evolution pattern of C. cassiicola isolates. Virulence analysis showed that there is an interaction between isolates and clones, indicating the differences of each isolates virulence to six clones. Agro-climatic conditions and host clones influenced the virulence of isolates and rDNA-ITS sequence variation. Analysis of rDNA-ITS showed that there were three of Single Nucleotide Polymorphism (SNP) that separated of isolates into 5 haplotypes. Most of the isolates belonging to the haplotype 1. Phylogenetic analysis indicated that C. cassiicola have a high diversity, however the clustering did not indicate country and host species of isolates. This information will be very useful on developing strategies of disease management and rubber plant breeding towards resistance to CLF disease.
Shelf-life of reduced-fat white chocolate fillings using iota-carrageenan
Authors: Dias João , Alvarenga Nuno , Sousa Isabel
Published: December 2017

The conservation of traditional chocolate fillings can present some hurdles due to the use of perishable raw matters, physical changes during processing and to the influence of external factors, which tends to shorten shelf-life of traditional filled pralinés to only 3-4 months. The aim of this study was to evaluate the influence of the concentration of iota-carrageenan on chemical, rheological, image analysis and microbial properties of reduced-fat white chocolate fillings during storage time. Two batches of reduced-fat filling were produced using white chocolate, commercial grade sugar, skimmed milk, inverted sugar and iota-carrageenan (at 0.5 % w/w and 1.0 % w/w concentration) and stored at 4 ºC during 12 months. A control batch with no hydrocolloid was also produced. The results presented a decrease in pH, aw and moisture during storage time. The rheological characterization concluded that all formulations presented a shearthinning behaviour and both flow index (n) and consistency (K) were correlated with iota-carrageenan concentration and with storage time. The concentration of iota-carrageenan did not influence the digital image analysis of chocolate fillings, but a shift was observed during storage time, especially at the end. The microbial analysis showed a positive correlation to storage time in the formulation using 1.0 % iota-carrageenan, nevertheless all results were quite acceptable and within the recommended safety values.
Improvement effect of nitrogen fertilizer and plant density on wheat (Triticum aestivum L.) seed deterioration and yield
Authors: Mosanaei Hedieh , AjamNorozi Hossein , Dadashi Mohammad Reza , Faraji Abolfazleh , Pessarakli Mohammad
Published: December 2017

In order to study the effect of seed deterioration, plant density and nitrogen fertilizer application on yield, yield components and somequalitative traits of wheat, a field experiment was conducted in Golestan province of Iran, as split factorial in the randomized completeblock design, with four replications in two growing seasons, 2014-2015 and 2015-2016. The experimental treatments included seedquality at 4 levels (control, 15, 30, and 45 hours of accelerated deterioration), plant density at two levels (350 and 420 plants/m) and nitrogen consumption at 3 levels (recommended rate, 15 and 30 percentages higher than the recommended rate, i.e., 125, 143.75, and162.5 kg N fertilizer ha, respectively). All quantitative traits (plant height, spike length, number of seeds per spike, number of spikeletsper spike, weight of 1000 seed, grain yield, straw yield, biological yield and harvest index) and quality traits (yield and protein content,nitrogen content, yield and starch content) were significantly different in different years. Application of recommended rate of nitrogenfertilizer in the first and the second year resulted in the highest average of number of seeds per spike and spike length. The highestgrain yield was achieved in the recommended and 30% higher than the recommended application rate of nitrogen fertilizer (4061.9 and4166.3 kg/ha, respectively) in the second year. Seed deterioration caused a significant reduction in yield and the yield components, sothe highest level of seed deteriorations in the first and the second years decreased 34.11 and 22.63% of the grain yield compared tothe control treatment. The highest protein content was achieved in the second year with the application of nitrogen 30% higher than therecommended rate (with a mean of 623.6 kg/ha), which increased by about 23% compared to the overall average. Seed deteriorationreduced the starch content, so that the highest mean was in non-deterioration in the second year (68.13%), which increased by 10%compared with that of the overall average. The lowest starch content was achieved at the highest level of deterioration (45 hours) in thefirst year (55.63%). In general, the results indicated that seed deterioration had negative effects on quantitative and some qualitativetraits, but the application of more nitrogen fertilizer and higher plant density reduced the negative effects of deterioration and improvedgrain yield and quality.
Ferrimagnetic Iron Sulfide Formation and Methane Venting Across the Paleocene‐Eocene Thermal Maximum in Shallow Marine Sediments, Ancient West Siberian Sea
Authors: Rudmin Maxim , Roberts Andrew P. , Horng Chorng‐Shern , Mazurov Aleksey , Savinova Olesya , Ruban Aleksey , Kashapov Roman , Veklich Maxim
Published: December 2017

Authigenesis of ferrimagnetic iron sulfide minerals (greigite and monoclinic pyrrhotite) occurred across the Paleocene‐Eocene Thermal Maximum (PETM) within the Bakchar oolitic ironstone in southeastern Western Siberia. Co‐occurrence of these minerals is associated with diagenetic environments that support anaerobic oxidation of methane, which has been validated by methane fluid inclusion analysis in the studied sediments. In modern settings, such ferrimagnetic iron sulfide formation is linked to upward methane diffusion in the presence of minor dissolved sulfide ions. The PETM was the most extreme Cenozoic global warming event and massive methane mobilization has been proposed as a major contributor to the globally observed warming and carbon isotope excursion associated with the PETM. The studied sediments provide rare direct evidence for methane mobilization during the PETM. Magnetic iron sulfide formation associated with methanogenesis in the studied sediments can be explained by enhanced local carbon burial across the PETM. While there is no strong evidence to link local methane venting with more widespread methane mobilization and global warming, the magnetic, petrographic, and geochemical approach used here is applicable to identifying authigenic minerals that provide telltale signatures of methane mobility that can be used to assess methane formation and mobilization through the PETM and other hyperthermal climatic events.
Changes in Fe Oxidation Rate in Hydrothermal Plumes as a Potential Driver of Enhanced Hydrothermal Input to Near‐Ridge Sediments During Glacial Terminations
Authors: Cullen J. T. , Coogan L. A.
Published: December 2017

Recent studies have hypothesized that changes in sea level due to glacial‐interglacial cycles lead to changes in the rate of melt addition to the crust at mid‐ocean ridges with globally significant consequences. Arguably the most compelling evidence for this comes from increases in the hydrothermal component in near‐ridge sediments during glacial‐interglacial transitions. Here we explore the hypothesis that changes in ocean bottom water [O2] and pH across glacial‐interglacial transitions would lead to changes in the rate of Fe oxidation in hydrothermal plumes. A simple model shows that a several fold increase in the rate of Fe oxidation is expected at glacial‐interglacial transitions. Uncertainty in bottom water chemistry and the relationship between oxidation and sedimentation rates prevent direct comparison of the model and data. However, it appears that the null hypothesis of invariant hydrothermal vent fluxes into ocean bottom water that changed in O2 content and pH across these transitions cannot currently be discounted.
Rapid Water Transport by Long‐Lasting Modon Eddy Pairs in the Southern Midlatitude Oceans
Authors: Hughes Chris W. , Miller Peter I.
Published: December 2017

Water in the ocean is generally carried with the mean flow, mixed by eddies, or transported westward by coherent eddies at speeds close to the long baroclinic Rossby wave speed. Modons (dipole eddy pairs) are a theoretically predicted exception to this behavior, which can carry water to the east or west at speeds much larger than the Rossby wave speed, leading to unusual transports of heat, nutrients, and carbon. We provide the first observational evidence of such rapidly moving modons propagating over large distances. These modons are found in the midlatitude oceans around Australia, with one also seen in the South Atlantic west of the Agulhas region. They can travel at more than 10 times the Rossby wave speed of 1–2 cm s−1 and typically persist for about 6 months carrying their unusual water mass properties with them, before splitting into individual vortices, which can persist for many months longer.
Volcano and Ship Tracks Indicate Excessive Aerosol‐Induced Cloud Water Increases in a Climate Model
Authors: Toll Velle , Christensen Matthew , Gassó Santiago , Bellouin Nicolas
Published: December 2017

Aerosol‐cloud interaction is the most uncertain mechanism of anthropogenic radiative forcing of Earth's climate, and aerosol‐induced cloud water changes are particularly poorly constrained in climate models. By combining satellite retrievals of volcano and ship tracks in stratocumulus clouds, we compile a unique observational data set and confirm that liquid water path (LWP) responses to aerosols are bidirectional, and on average the increases in LWP are closely compensated by the decreases. Moreover, the meteorological parameters controlling the LWP responses are strikingly similar between the volcano and ship tracks. In stark contrast to observations, there are substantial unidirectional increases in LWP in the Hadley Centre climate model, because the model accounts only for the decreased precipitation efficiency and not for the enhanced entrainment drying. If the LWP increases in the model were compensated by the decreases as the observations suggest, its indirect aerosol radiative forcing in stratocumulus regions would decrease by 45%.
Tidal Conversion and Mixing Poleward of the Critical Latitude (an Arctic Case Study)
Authors: Rippeth Tom P. , Vlasenko Vasiliy , Stashchuk Nataliya , Scannell Brian D. , Green J. A. Mattias , Lincoln Ben J. , Bacon Sheldon
Published: December 2017

The tides are a major source of the kinetic energy supporting turbulent mixing in the global oceans. The prime mechanism for the transfer of tidal energy to turbulent mixing results from the interaction between topography and stratified tidal flow, leading to the generation of freely propagating internal waves at the period of the forcing tide. However, poleward of the critical latitude (where the period of the principal tidal constituent exceeds the local inertial period), the action of the Coriolis force precludes the development of freely propagating linear internal tides. Here we focus on a region of sloping topography, poleward of the critical latitude, where there is significant conversion of tidal energy and the flow is supercritical (Froude number, Fr > 1). A high‐resolution nonlinear modeling study demonstrates the key role of tidally generated lee waves and supercritical flow in the transfer of energy from the barotropic tide to internal waves in these high‐latitude regions. Time series of flow and water column structure from the region of interest show internal waves with characteristics consistent with those predicted by the model, and concurrent microstructure dissipation measurements show significant levels of mixing associated with these internal waves. The results suggest that tidally generated lee waves are a key mechanism for the transfer of energy from the tide to turbulence poleward of the critical latitude.
Analysis of the Duration of Rising Tone Chorus Elements
Authors: Teng S. , Tao X. , Xie Y. , Zonca F. , Chen L. , Fang W. B. , Wang S.
Published: December 2017

The duration of chorus elements is an important parameter to understand chorus excitation and to quantify the effects of nonlinear wave‐particle interactions on energetic electron dynamics. In this work, we analyze the duration of rising tone chorus elements statistically using Van Allen Probes data. We present the distribution of chorus element duration (τ) as a function of magnetic local time (MLT) and the geomagnetic activity level characterized by auroral electrojet (AE) index. We show that the typical value of τ for nightside and dawnside is about 0.12 s, smaller than that for dayside and duskside by about a factor of 2 to 4. Using a previously developed hybrid code, DAWN, we suggest that the background magnetic field inhomogeneity might be an important factor in controlling the chorus element duration. We also report that τ is larger during quiet times and shorter during moderate and active periods; this result is consistent with the MLT dependence of τ and the occurrence pattern of chorus waves at different levels of geomagnetic activity. We then investigate the correlation between τ and the frequency chirping rate (Γ). We show that, from observation, τ scales with Γ as
, suggesting that statistically the frequency range of chorus elements (τΓ) should be roughly the same for different elements. These findings should be useful to the further development of a theoretical model of chorus excitation and to the quantification of nonlinear wave‐particle interactions on energetic electron dynamics.
Kinematics of Active Deformation Across the Western Kunlun Mountain Range (Xinjiang, China) and Potential Seismic Hazards Within the Southern Tarim Basin
Authors: Guilbaud Christelle , Simoes Martine , Barrier Laurie , Laborde Amandine , Van der Woerd Jérôme , Li Haibing , Tapponnier Paul , Coudroy Thomas , Murray Andrew
Published: December 2017

The Western Kunlun mountain range is a slowly converging intracontinental orogen where deformation rates are too low to be properly quantified from geodetic techniques. This region has recorded little seismicity, but the recent July 2015 (Mw 6.4) Pishan earthquake shows that this mountain range remains seismic. To quantify the rate of active deformation and the potential for major earthquakes in this region, we combine a structural and quantitative morphological analysis of the Yecheng–Pishan fold, along the topographic mountain front in the epicentral area. Using a seismic profile, we derive a structural cross section in which we identify the fault that broke during the Pishan earthquake, an 8–12 km deep blind ramp beneath the Yecheng–Pishan fold. Combining satellite images and DEMs, we achieve a detailed morphological analysis of the Yecheng–Pishan fold, where we find nine levels of incised fluvial terraces and alluvial fans. From their incision pattern and using age constraints retrieved on some of these terraces from field sampling, we quantify the slip rate on the underlying blind ramp to 0.5 to 2.5 mm/yr, with a most probable long‐term value of 2 to 2.5 mm/yr. The evolution of the Yecheng–Pishan fold is proposed by combining all structural, morphological, and chronological observations. Finally, we compare the seismotectonic context of the Western Kunlun to what has been proposed for the Himalayas of Central Nepal. This allows for discussing the possibility of M ≥ 8 earthquakes if the whole decollement across the southern Tarim Basin is seismically locked and ruptures in one single event.
Improved Phase Corrections for Transoceanic Tsunami Data in Spatial and Temporal Source Estimation: Application to the 2011 Tohoku Earthquake
Authors: Ho Tung‐Cheng , Satake Kenji , Watada Shingo
Published: December 2017

Systemic travel time delays of up to 15 min relative to the linear long waves for transoceanic tsunamis have been reported. A phase correction method, which converts the linear long waves into dispersive waves, was previously proposed to consider seawater compressibility, the elasticity of the Earth, and gravitational potential change associated with tsunami motion. In the present study, we improved this method by incorporating the effects of ocean density stratification, actual tsunami raypath, and actual bathymetry. The previously considered effects amounted to approximately 74% for correction of the travel time delay, while the ocean density stratification, actual raypath, and actual bathymetry, contributed to approximately 13%, 4%, and 9% on average, respectively. The improved phase correction method accounted for almost all the travel time delay at far‐field stations. We performed single and multiple time window inversions for the 2011 Tohoku tsunami using the far‐field data (>3 h travel time) to investigate the initial sea surface displacement. The inversion result from only far‐field data was similar to but smoother than that from near‐field data and all stations, including a large sea surface rise increasing toward the trench followed by a migration northward along the trench. For the forward simulation, our results showed good agreement between the observed and computed waveforms at both near‐field and far‐field tsunami gauges, as well as with satellite altimeter data. The present study demonstrates that the improved method provides a more accurate estimate for the waveform inversion and forward prediction of far‐field data.
A Simple and Universal Aerosol Retrieval Algorithm for Landsat Series Images Over Complex Surfaces
Authors: Wei Jing , Huang Bo , Sun Lin , Zhang Zhaoyang , Wang Lunche , Bilal Muhammad
Published: December 2017

Operational aerosol optical depth (AOD) products are available at coarse spatial resolutions from several to tens of kilometers. These resolutions limit the application of these products for monitoring atmospheric pollutants at the city level. Therefore, a simple, universal, and high‐resolution (30 m) Landsat aerosol retrieval algorithm over complex urban surfaces is developed. The surface reflectance is estimated from a combination of top of atmosphere reflectance at short‐wave infrared (2.22 μm) and Landsat 4–7 surface reflectance climate data records over densely vegetated areas and bright areas. The aerosol type is determined using the historical aerosol optical properties derived from the local urban Aerosol Robotic Network (AERONET) site (Beijing). AERONET ground‐based sun photometer AOD measurements from five sites located in urban and rural areas are obtained to validate the AOD retrievals. Terra MODerate resolution Imaging Spectrometer Collection (C) 6 AOD products (MOD04) including the dark target (DT), the deep blue (DB), and the combined DT and DB (DT&DB) retrievals at 10 km spatial resolution are obtained for comparison purposes. Validation results show that the Landsat AOD retrievals at a 30 m resolution are well correlated with the AERONET AOD measurements (R2 = 0.932) and that approximately 77.46% of the retrievals fall within the expected error with a low mean absolute error of 0.090 and a root‐mean‐square error of 0.126. Comparison results show that Landsat AOD retrievals are overall better and less biased than MOD04 AOD products, indicating that the new algorithm is robust and performs well in AOD retrieval over complex surfaces. The new algorithm can provide continuous and detailed spatial distributions of AOD during both low and high aerosol loadings.
Snow Cover and Vegetation‐Induced Decrease in Global Albedo From 2002 to 2016
Authors: Li Qiuping , Ma Mingguo , Wu Xiaodan , Yang Hong
Published: December 2017

Land surface albedo is an essential parameter in regional and global climate models, and it is markedly influenced by land cover change. Variations in the albedo can affect the surface radiation budget and further impact the global climate. In this study, the interannual variation of albedo from 2002 to 2016 was estimated on the global scale using Moderate Resolution Imaging Spectroradiometer (MODIS) datasets. The presence and causes of the albedo changes for each specific region were also explored. From 2002 to 2016, the MODIS‐based albedo decreased globally, snow cover declined by 0.970 (percent per pixel), while the seasonally integrated normalized difference vegetation index increased by 0.175. Some obvious increases in the albedo were detected in Central Asia, northeastern China, parts of the boreal forest in Canada, and the temperate steppe in North America. In contrast, noticeable decreases in the albedo were found in the Siberian tundra, Europe, southeastern Australia, and northeastern regions of North America. In the Northern Hemisphere, the greening trend at high latitudes made more contribution to the decline in the albedo. However, the dramatic fluctuation of snow‐cover at midlatitudes predominated in the change of albedo. Our analysis can help to understand the roles that vegetation and snow cover play in the variation of albedo on global and regional scales.
Drivers of Seasonal Variability in Marine Boundary Layer Aerosol Number Concentration Investigated Using a Steady State Approach
Authors: Mohrmann Johannes , Wood Robert , McGibbon Jeremy , Eastman Ryan , Luke Edward
Published: December 2017

Marine boundary layer (MBL) aerosol particles affect the climate through their interaction with MBL clouds. Although both MBL clouds and aerosol particles have pronounced seasonal cycles, the factors controlling seasonal variability of MBL aerosol particle concentration are not well constrained. In this paper an aerosol budget is constructed representing the effects of wet deposition, free‐tropospheric entrainment, primary surface sources, and advection on the MBL accumulation mode aerosol number concentration (Na). These terms are then parameterized, and by assuming that on seasonal time scales Na is in steady state, the budget equation is rearranged to form a diagnostic equation for Na based on observable variables. Using data primarily collected in the subtropical northeast Pacific during the MAGIC campaign (Marine ARM (Atmospheric Radiation Measurement) GPCI (GCSS Pacific Cross‐Section Intercomparison) Investigation of Clouds), estimates of both mean summer and winter Na concentrations are made using the simplified steady state model and seasonal mean observed variables. These are found to match well with the observed Na. To attribute the modeled difference between summer and winter aerosol concentrations to individual observed variables (e.g., precipitation rate and free‐tropospheric aerosol number concentration), a local sensitivity analysis is combined with the seasonal difference in observed variables. This analysis shows that despite wintertime precipitation frequency being lower than summer, the higher winter precipitation rate accounted for approximately 60% of the modeled seasonal difference in Na, which emphasizes the importance of marine stratocumulus precipitation in determining MBL aerosol concentrations on longer time scales.
The Diurnal Cycle of Clouds and Precipitation at the ARM SGP Site: An Atmospheric State‐Based Analysis and Error Decomposition of a Multiscale Modeling Framework Simulation
Authors: Zhao Wei , Marchand Roger , Fu Qiang
Published: December 2017

Long‐term reflectivity data collected by a millimeter cloud radar at the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site are used to examine the diurnal cycle of clouds and precipitation and are compared with the diurnal cycle simulated by a Multiscale Modeling Framework (MMF) climate model. The study uses a set of atmospheric states that were created specifically for the SGP and for the purpose of investigating under what synoptic conditions models compare well with observations on a statistical basis (rather than using case studies or seasonal or longer time scale averaging). Differences in the annual mean diurnal cycle between observations and the MMF are decomposed into differences due to the relative frequency of states, the daily mean vertical profile of hydrometeor occurrence, and the (normalized) diurnal variation of hydrometeors in each state. Here the hydrometeors are classified as cloud or precipitation based solely on the reflectivity observed by a millimeter radar or generated by a radar simulator. The results show that the MMF does not capture the diurnal variation of low clouds well in any of the states but does a reasonable job capturing the diurnal variations of high clouds and precipitation in some states. In particular, the diurnal variations in states that occur during summer are reasonably captured by the MMF, while the diurnal variations in states that occur during the transition seasons (spring and fall) are not well captured. Overall, the errors in the annual composite are due primarily to errors in the daily mean of hydrometeor occurrence (rather than diurnal variations), but errors in the state frequency (that is, the distribution of weather states in the model) also play a significant role.
Multiyear Composite View of Ozone Enhancements and Stratosphere‐to‐Troposphere Transport in Dry Intrusions of Northern Hemisphere Extratropical Cyclones
Authors: Jaeglé Lyatt , Wood Robert , Wargan Krzysztof
Published: December 2017

We examine the role of extratropical cyclones in stratosphere‐to‐troposphere (STT) exchange with cyclone‐centric composites of O3retrievals from the Microwave Limb Sounder (MLS) and the Tropospheric Emission Spectrometer (TES), contrasting them to composites obtained with the Modern‐Era Retrospective‐analysis for Research and Applications (MERRA and MERRA‐2) reanalyses and the GEOS‐Chem chemical transport model. We identify 15,978 extratropical cyclones in the northern hemisphere (NH) for 2005–2012. The lowermost stratosphere (261 hPa) and middle troposphere (424 hPa) composites feature a 1,000 km wide O3enhancement in the dry intrusion (DI) airstream to the southwest of the cyclone center, coinciding with a lowered tropopause, enhanced potential vorticity, and decreased H2O. MLS composites at 261 hPa show that the DI O3enhancements reach a 210 ppbv maximum in April. At 424 hPa, TES composites display maximum O3enhancements of 27 ppbv in May. The magnitude and seasonality of these enhancements are captured by MERRA and MERRA‐2, but GEOS‐Chem is a factor of 2 too low. The MERRA‐2 composites show that the O3‐rich DI forms a vertically aligned structure between 300 and 800 hPa, wrapping cyclonically with the warm conveyor belt. In winter and spring DIs, O3is enhanced by 100 ppbv or 100–130% at 300 hPa, with significant enhancements below 500 hPa (6–20 ppbv or 15–30%). We estimate that extratropical cyclones result in a STT flux of 119 ± 56 Tg O3 yr−1, accounting for 42 ± 20% of the NH extratropical O3STT flux. The STT flux in cyclones displays a strong dependence on westerly 300 hPa wind speeds.