bluuebunny/crossref_metadata_2025 huggingface dataset:
Mise en débat de la figure de l'expert dans les échanges en ligne sur les changements climatiques: héros, anti-héros et représentations de la science
Authors: Campion Baptiste
Published: October 2013

Cet article rend compte d’un travail exploratoire étudiant les représentations de la science et des scientifiques débattues et diffusées dans des débats en ligne entre non professionnels de la science au sujet du réchauffement climatique anthropique. Nous avons analysé de manière qualitative et compréhensive les commentaires sur deux sites où sont discutées des thèses dites « sceptiques ». Les résultats montrent que ces échanges sont le fait de communautés actives réduites développant un propos assez structuré. Les défenseurs de positions sceptiques prétendent produire un véritable discours scientifique, et développent une représentation de la science où les sceptiques incarnent l’idéal scientifique véritable face à des institutions et des chercheurs perçus comme corrompus et animés par l’idéologie. Les opposants aux vues sceptiques mettent en avant les mécanismes propres à la littérature scientifique pour refuser aux sceptiques le statut d’experts.
Au nom de la lutte contre le changement climatique : le mécanisme pour un développement propre et ses travers
Authors: Demaze Moïse Tsayem
Published: October 2013

Institué par le protocole de Kyoto, le Mécanisme pour un Développement Propre (MDP) permet aux pays développés de remplir une partie de leurs engagements de réduction de leurs émissions de gaz à effet de serre (EGES) dans le cadre de projets réalisés dans des pays en développement. De la sorte, les pays développés peuvent être crédités d’EGES correspondant au volume évité ou réduit dans des pays en développement, et les pays en développement peuvent se targuer de se développer « proprement ». L’utilisation du MDP a suscité de nombreuses critiques, voire des controverses : réduction non avérée des EGES, caractère douteux ou insuffisamment « propre » des technologies transférées dans des pays en développement, inégale répartition géographique et sectorielle des projets, faiblesse ou absence de développement durable que les projets MDP sont censés entraîner dans les pays en développement, etc. Cet article propose un inventaire et une évaluation de ces critiques, à partir du dépouillement et de l’analyse de deux bulletins d’informations rendant compte de la mise en œuvre des projets MDP dans le monde (Nouvelles Francophones du marché du carbone et du MDP, et Moniteur du MDP et de la Mise en Œuvre Conjointe). Les critiques inventoriées et évaluées ont été confrontées aux expertises faites sur le MDP par deux Organisations Non Gouvernementale Internationales (ONGI) spécialisées dans le suivi du MDP : CDM Watch et NOE 21. Les entretiens menés avec les responsables de ces ONGI ont permis d’évaluer la pertinence des critiques dont le MDP est l’objet, ainsi que la portée de ce mécanisme. Les résultats de cette étude amènent à s’interroger sur l’efficacité réelle du MDP et sur les reformes envisagées dans le but de faire en sorte qu’il contribue davantage aux efforts de réduction des EGES.
Modélisation de réseaux écologiques et impacts des choix méthodologiques sur leur configuration spatiale : analyse de cas en Estrie (Québec, Canada)
Authors: Bernier Amélie , Théau Jérôme
Published: October 2013

Les réseaux écologiques visent à maintenir la biodiversité et les processus écologiques en protégeant les habitats et leur connectivité. Plusieurs approches peuvent être utilisées pour délimiter les composantes de ces réseaux, et ce, à chaque étape de la conception. Ces différentes possibilités constituent une source majeure d’incertitude qui influence la configuration spatiale des réseaux obtenus, mais qui est peu étudiée et documentée. Dans cette étude, plusieurs méthodes ont été appliquées aux étapes de sélection des zones nodales et de tracé des corridors sur un même territoire en Estrie, Québec. L’étude visait à concevoir un réseau écologique adapté à une espèce indicatrice, le Grand Pic (Dryocopus pileatus). Deux méthodes de sélection des zones nodales ont été testées : l’analyse multicritères et l’indice de qualité d’habitat. Ces deux méthodes, reprises également à l’étape de création des matrices de résistance aux déplacements, ont été combinées à trois méthodes de tracé des corridors : le chemin de moindre coût, le corridor de moindre coût et la théorie des circuits. Six réseaux écologiques résultants ont été créés et comparés. Les résultats montrent d’importantes différences de configuration spatiale entre les réseaux que ce soit en termes de superficie et de périmètre des différents éléments que de largeurs de corridors. Ces résultats sont discutés en lien avec deux facteurs limitants concernant ces étapes méthodologiques soient la disponibilité des données et la représentativité des modèles. Des pistes de réflexion sont également proposées afin d’outiller davantage les décideurs dans leurs choix face aux nombreux scénarios possibles de réseaux écologiques.
Multifonctionnalité des espaces végétalisés urbains
Authors: Selmi Wissal , Weber Christiane , Mehdi Lotfi
Published: October 2013

Les espaces végétalisés urbains (EVU), souvent considérés comme un décor urbain, font depuis les 20 dernières années l’objet de nombreux travaux scientifiques, et ce non seulement pour leur valeur socio-urbanistique, mais aussi pour leur valeur écologique (Clergeau, 2012). Actuellement, de nouveaux concepts-clés sont associés aux espaces végétalisés urbains, comme le concept de « multifonctionnalité » et celui de « services écosystémiques » (SE) (Bastian et al., 2011). Cependant, l’absence d’un consensus terminologique sur ces différents concepts limite leur utilisation et leur intégration dans le processus décisionnel, par exemple dans l’établissement des trames vertes urbaines. Cet article propose d’étudier la prise en compte de ces concepts par la communauté scientifique à partir d’une revue de la littérature. Le cadre conceptuel actuel y sera discuté en relevant certaines imprécisions terminologiques. Enfin, différentes approches d’évaluation des SE urbains pouvant fournir de nouvelles orientations pour la mise en œuvre de la future trame verte urbaine (TVU), seront aussi abordées.
Differential Uptake of Nanoparticles and Microparticles by Pulmonary APC Subsets Induces Discrete Immunological Imprints
Authors: Hardy Charles L. , LeMasurier Jeanne S. , Mohamud Rohimah , Yao Jun , Xiang Sue D. , Rolland Jennifer M. , O’Hehir Robyn E. , Plebanski Magdalena
Published: October 2013

There is increasing interest in the use of engineered particles for biomedical applications, although questions exist about their proinflammatory properties and potential adverse health effects. Lung macrophages and dendritic cells (DC) are key regulators of pulmonary immunity, but little is known about their uptake of different sized particles or the nature of the induced immunological imprint. We investigated comparatively the immunological imprints of inert nontoxic polystyrene nanoparticles 50 nm in diameter (PS50G) and 500 nm in diameter (PS500G). Following intratracheal instillation into naive mice, PS50G were preferentially taken up by alveolar and nonalveolar macrophages, B cells, and CD11b+ and CD103+ DC in the lung, but exclusively by DC in the draining lymph node (LN). Negligible particle uptake occurred in the draining LN 2 h postinstillation, indicating that particle translocation does not occur via lymphatic drainage. PS50G but not PS500G significantly increased airway levels of mediators that drive DC migration/maturation and DC costimulatory molecule expression. Both particles decreased frequencies of stimulatory CD11b+MHC class IIhi allergen-laden DC in the draining LN, with PS50G having the more pronounced effect. These distinctive particle imprints differentially modulated induction of acute allergic airway inflammation, with PS50G but not PS500G significantly inhibiting adaptive allergen-specific immunity. Our data show that nanoparticles are taken up preferentially by lung APC stimulate cytokine/chemokine production and pulmonary DC maturation and translocate to the lung-draining LN via cell-associated transport. Collectively, these distinctive particle imprints differentially modulate development of subsequent lung immune responses. These findings support the development of lung-specific particulate vaccines, drug delivery systems, and immunomodulators.
Targeting F Box Protein Fbxo3 To Control Cytokine-Driven Inflammation
Authors: Mallampalli Rama K. , Coon Tiffany A. , Glasser Jennifer R. , Wang Claire , Dunn Sarah R. , Weathington Nathaniel M. , Zhao Jing , Zou Chunbin , Zhao Yutong , Chen Bill B.
Published: October 2013

Cytokine-driven inflammation underlies the pathobiology of a wide array of infectious and immune-related disorders. The TNFR-associated factor (TRAF) proteins have a vital role in innate immunity by conveying signals from cell surface receptors to elicit transcriptional activation of genes encoding proinflammatory cytokines. We discovered that a ubiquitin E3 ligase F box component, termed Fbxo3, potently stimulates cytokine secretion from human inflammatory cells by mediating the degradation of the TRAF inhibitory protein, Fbxl2. Analysis of the Fbxo3 C-terminal structure revealed that the bacterial-like ApaG molecular signature was indispensible for mediating Fbxl2 disposal and stimulating cytokine secretion. By targeting this ApaG motif, we developed a highly unique, selective genus of small-molecule Fbxo3 inhibitors that by reducing TRAF protein levels, potently inhibited cytokine release from human blood mononuclear cells. The Fbxo3 inhibitors effectively lessened the severity of viral pneumonia, septic shock, colitis, and cytokine-driven inflammation systemically in murine models. Thus, pharmacological targeting of Fbxo3 might be a promising strategy for immune-related disorders characterized by a heightened host inflammatory response.
Salmonella Infection Induces Recruitment of Caspase-8 to the Inflammasome To Modulate IL-1β Production
Authors: Man Si Ming , Tourlomousis Panagiotis , Hopkins Lee , Monie Tom P. , Fitzgerald Katherine A. , Bryant Clare E.
Published: October 2013

Nucleotide-binding oligomerization domain–like receptors (NLRs) detect pathogens and danger-associated signals within the cell. Salmonella enterica serovar Typhimurium, an intracellular pathogen, activates caspase-1 required for the processing of the proinflammatory cytokines, pro–IL-1β and pro–IL-18, and pyroptosis. In this study, we show that Salmonella infection induces the formation of an apoptosis-associated specklike protein containing a CARD (ASC)–Caspase-8–Caspase-1 inflammasome in macrophages. Caspase-8 and caspase-1 are recruited to the ASC focus independently of one other. Salmonella infection initiates caspase-8 proteolysis in a manner dependent on NLRC4 and ASC, but not NLRP3, caspase-1 or caspase-11. Caspase-8 primarily mediates the synthesis of pro-IL-1β, but is dispensable for Salmonella-induced cell death. Overall, our findings highlight that the ASC inflammasome can recruit different members of the caspase family to induce distinct effector functions in response to Salmonella infection.
Evolution of B Cell Responses to Clec9A-Targeted Antigen
Authors: Park Hae-Young , Light Amanda , Lahoud Mireille H. , Caminschi Irina , Tarlinton David M. , Shortman Ken
Published: October 2013

The response of B cells to Ag targeted to Clec9A on dendritic cells was followed using the hapten nitrophenol (NP) conjugated to rat Ig carrier. Injection of small amounts of NP conjugated to anti-Clec9A in the absence of adjuvants gave high and very prolonged Ab responses, approaching those obtained by high doses of nontargeted NP–protein conjugates with alum adjuvant. The response to NP–anti-Clec9A included the transient formation of germinal centers, maturation of Ab affinity, and some memory B cell formation. Serum Ab titers remained high 35 wk postimmunization, well after the initial follicular response had faded. The results suggest Clec9A-targeting strategies for improving Ab responses to vaccine Ags.
A Longitudinal Career-Focused Block for Third-Year Pediatrics Residents
Authors: Rosenberg Adam A. , Lockspeiser Tai , Lane J. Lindsey , Nomura Yosuke , Schmitter Pat , Urban Kathy , Jimenez Sheilah , Hanson Janice
Published: October 2013

Background

The traditional 1-month training blocks in pediatrics may fail to provide sufficient exposure to develop the knowledge, skills, and attitudes residents need for practice and may not be conducive to mentoring relationships with faculty and continuity with patients.

Intervention

We created a 4-month career-focused experience (CFE) for third-year residents. The CFE included block time and longitudinal experiences in different content areas related to residents' choice of urban and rural primary care, hospitalist medicine, or subspecialty care (prefellowship). Content was informed by graduate surveys, focus groups with primary care pediatricians and hospitalists, and interviews with fellowship directors. Outcomes were assessed via before and after surveys of residents' attitudes and skills, assessment of skills with an objective structured clinical examination (OSCE), and interviews with residents and mentors.

Results

Twenty-three of 49 third-year residents took part in the first 2 years of CFE. Two residents dropped out, leaving 21 who completed the 4-month experience (9 in primary care, 2 in hospitalist medicine, and 10 in a subspecialty). Residents reported improvement in their clinical skills, increased satisfaction with faculty mentoring and evaluation, and the ability to focus on what was important to their careers. OSCE performance did not differ between residents who completed the CFE and those who did not. Administrative burden was high.

Conclusions

Four-month career-focused training for pediatrics residents is feasible and may be effective in meeting part of the new requirement for 6 months of career-focused training during pediatrics residency.
Balancing Industry Needs against Global Competitiveness: A Challenge for the Australian Vegetable Industry
Authors: Ariyawardana Anoma , Collins Ray
Published: October 2013

The Australian vegetable industry is a significant contributor to the national economy and regional development, generating employment opportunities both on-farm and along the farm-to-market chain. However, the high cost structure of the industry has negatively affected its competitiveness and production is declining, resulting in the relocation of some processing facilities to other countries and increasing imports. These outcomes threaten the future viability of the industry and impact on food-safety-conscious consumers in Australia. Thus, the aim of this paper is to review policy issues along the producer to consumer chain and discuss how key stakeholders could be affected by alternative policy options. The current context of the vegetable industry shows that Australia faces a challenge to find appropriate policy solutions to achieve global competitiveness and secure the interests of its stakeholders while at the same time adopting a market-based policy approach to its food industry.
Adoption of Integrated Farming in Thailand Delivered by the Royal Development Study Centres
Authors: Bunbongkarn Suleeporn , Pongquan Soparth
Published: October 2013

This study assesses the extent to which integrated farming has been adopted in response to support from Royal Development Study Centres (RDSCs) in Thailand. Primary data were collected from 129 sample farmers who lived in the area surrounding two RDSCs and participated in integrated farming programmes. Both RDSCs are located in central Thailand and follow similar modes and processes in promoting integrated farming knowledge and technology extension. Linear regression was used to determine the factors influencing the levels of adoption in the two areas. The findings help to explain variations in the uptake and scale of integrated farming adoption. Policy implications regarding the adoption and promotion of integrated farming are highlighted.
Looking at Agricultural Innovation Platforms through an Innovation Champion Lens
Authors: Klerkx Laurens , Adjei-Nsiah Samuel , Adu-Acheampong Richard , Saïdou Aliou , Zannou Elizabeth , Soumano Lassine , Sakyi-Dawson Owuraku , van Paassen Annemarie , Nederlof Suzanne
Published: October 2013

The concept of an innovation platform is increasingly used in interventions inspired by agricultural innovation systems thinking, as a way of bringing stakeholders from a sector together to enable transformative change. An essential role on such innovation platforms is thought to be that of the ‘innovation champion’, but this role has so far not been unravelled. In this paper, by applying insights from management science to analyse three innovation platforms in West Africa from the Convergence of Sciences – Strengthening Innovation Systems programme (CoS–SIS), different types of innovation champions are mapped. The authors conclude that making a distinction among different types of innovation champions can be useful in identifying members for innovation platforms, but that the specifics of agricultural innovation appear not to be adequately captured by roles attributed to existing categories of innovation champions. Further research is needed to ascertain whether other categories exist, and how different innovation champions interact over time on agricultural innovation platforms.
Whole‐Genome Amplification of Single‐Cell Genomes for Next‐Generation Sequencing
Authors: Korfhage Christian , Fisch Evelyn , Fricke Evelyn , Baedker Silke , Loeffert Dirk
Published: October 2013

DNA sequence analysis and genotyping of biological samples using next‐generation sequencing (NGS), microarrays, or real‐time PCR is often limited by the small amount of sample available. A single cell contains only one to four copies of the genomic DNA, depending on the organism (haploid or diploid organism) and the cell‐cycle phase. The DNA content of a single cell ranges from a few femtograms in bacteria to picograms in mammalia. In contrast, a deep analysis of the genome currently requires a few hundred nanograms up to micrograms of genomic DNA for library formation necessary for NGS sequencing or labeling protocols (e.g., microarrays). Consequently, accurate whole‐genome amplification (WGA) of single‐cell DNA is required for reliable genetic analysis (e.g., NGS) and is particularly important when genomic DNA is limited. The use of single‐cell WGA has enabled the analysis of genomic heterogeneity of individual cells (e.g., somatic genomic variation in tumor cells). This unit describes how the genome of single cells can be used for WGA for further genomic studies, such as NGS. Recommendations for isolation of single cells are given and common sources of errors are discussed. Curr. Protoc. Mol. Biol. 104:7.14.1‐7.14.11. © 2013 by John Wiley & Sons, Inc.
Pyrosequencing: Powerful and Quantitative Sequencing Technology
Authors: Kreutz Martin , Hochstein Norbert , Kaiser Julia , Narz Frank , Peist Ralf
Published: October 2013

Pyrosequencing is a sequencing‐by‐synthesis method for DNA analysis that has emerged as a platform not only for de novo sequencing applications, but also for quantitative analysis of genomic methylation, single‐nucleotide polymorphisms, and allele quantification. In this unit, we describe a complete workflow from sample to result that is suitable for each of these applications. As cytosine conversion is a key element of successful methylation analysis using pyrosequencing, a support protocol for bisulfite treatment is also included. Curr. Protoc. Mol. Biol. 104:7.15.1‐7.15.23. © 2013 by John Wiley & Sons, Inc.
A numeric evaluation of attenuation from ambient noise correlation functions
Authors: Lawrence Jesse F. , Denolle Marine , Seats Kevin J. , Prieto Germán A.
Published: October 2013

The ambient noise correlation function (NCF) calculated between seismic stations contains, under appropriate conditions, accurate travel time information. However, NCF amplitudes are highly debated due to noise source intensity and distribution, seismic intrinsic attenuation, scattering, and elastic path effects such as focusing and defocusing. We prove with various numerical simulations that the NCFs calculated for a uniformly dispersive medium using the coherency method preserve accurate geometrical spreading and attenuation decay. We show that for a wide range of noise source distributions, the coherency of the noise correlation functions matches a Bessel function decaying exponentially with a specific attenuation coefficient. Conditions needed to obtain these results include averaging over long enough time intervals, a uniformly distributed seismic network, and a good distribution of far‐field noise sources. We also show that the estimated attenuation coefficient corresponds to the interstation and not the noise‐source‐to‐receiver structure.
On the statistics of urban heat island intensity
Authors: Zhou B. , Rybski D. , Kropp J. P.
Published: October 2013

We perform a systematic study of all cities in Europe to assess the Urban Heat Island (UHI) intensity by means of remotely sensed land surface temperature data. Defining cities as spatial clusters of urban land cover, we investigate the relationships of the UHI intensity, with the cluster size and the temperature of the surroundings. Our results show that in Europe, the UHI intensity in summer has a strong correlation with the cluster size, which can be well fitted by an empirical sigmoid model. Furthermore, we find a novel seasonality of the UHI intensity for individual clusters in the form of hysteresis‐like curves. We characterize the shape and identify apparent regional patterns.
Ice sheet grounding zone stabilization due to till compaction
Authors: Christianson Knut , Parizek Byron R. , Alley Richard B. , Horgan Huw J. , Jacobel Robert W. , Anandakrishnan Sridhar , Keisling Benjamin A. , Craig Brian D. , Muto Atsuhiro
Published: October 2013

Based on modeling motivated by new GPS and radio‐echo sounding surveys, a few‐kilometers‐long zone of Whillans Ice Stream, West Antarctica, just inland of the grounding line has higher basal shear stress than the ice farther upstream or the freely slipping ice shelf downstream. Data from this zone show a few‐meter‐high upwarp of the surface overlying a large fold extending through all internal radar layers observed. Flowband modeling shows that the fold can be generated by decreased basal lubrication beneath the upwarp. Basal topography alone cannot create this fold. Physical modeling and available data suggest that low‐amplitude tidal flexure of the ice shelf extends a few kilometers inland. Downward flexing of this grounded ice from the rising tide would compact subglacial till, resulting in higher basal shear stress. This result suggests that important processes influencing grounding line stability are not included in modern whole‐ice‐sheet models.
Nailing down the slip rate of the Altyn Tagh fault
Authors: He Jiankun , Vernant Philippe , Chéry Jean , Wang Weimin , Lu Shuangjiang , Ku Wenfei , Xia Wenhai , Bilham Roger
Published: October 2013

Previous estimates of the geodetic and geologic slip rates of the 1500 km long Altyn Tagh fault bordering the northern edge of the Tibetan plateau vary by a factor of five. Proposed reasons for these discrepancies include poor GPS geometry, interpretative errors in terrace morphology, and changes in fault slip rate over time. Here we present results from a new dense GPS array orthogonal to the fault at ~86.2°E that indicates a velocity of 9.0−3.2/+4.4 mm/yr, in close agreement with geomorphologic estimates at the same location. Our estimated geodetic slip rate is consistent with recent geological slip rates based on terrace offsets. The resulting mean combined geological and geodetic slip rate (9.0 ± 4.0 mm/yr) is remarkably uniform for the central ~800 km of the Altyn Tagh fault, significantly lower than early kinematic estimates and consistent with deformation elsewhere in Tibet and central Asia.
Two‐dimensional simulation of ionospheric variations in the vicinity of the epicenter of the Tohoku‐oki earthquake on 11 March 2011
Authors: Shinagawa H. , Tsugawa T. , Matsumura M. , Iyemori T. , Saito A. , Maruyama T. , Jin H. , Nishioka M. , Otsuka Y.
Published: October 2013

Unusual ionospheric variations were observed in the M9.0 Tohoku‐oki earthquake on 11 March 2011. Among various kinds of features in the ionosphere, significant depletion of total electron content (TEC) near the epicenter was observed after the earthquake. Although previous studies have suggested that the coseismic ionospheric variations are associated with atmospheric perturbation caused by vertical displacement of the sea surface, the mechanism of the TEC depletion has not been fully understood. In this paper, a two‐dimensional nonlinear nonhydrostatic compressible atmosphere‐ionosphere model is employed to investigate the ionospheric variations in the vicinity of the epicenter. The simulation results reveal that an impulsive pressure pulse produced by a sudden uplift of the sea surface leads to local atmospheric expansion in the thermosphere and that the expansion of the thermosphere combined with the effect of inclined magnetic field lines in the ionosphere causes the sudden TEC depletion above the epicenter region.
The role of vertical eddy flux in Southern Ocean heat uptake
Authors: Morrison A. K. , Saenko O. A. , Hogg A. McC. , Spence P.
Published: October 2013

The role of changing vertical eddy heat flux on Southern Ocean heat uptake is investigated in an idealized eddy‐permitting ocean model. Enhanced air‐sea heat flux drives deep‐reaching southern warming, due to a reduction in the isopycnal meridional temperature gradient and therefore decreased upward eddy heat flux. This mechanism is qualitatively similar in models with either permitted or parameterized eddies, due to its dependence on the isopycnal temperature gradient rather than the dynamical response of the eddy field. In contrast, increased wind stress drives mid‐depth Southern Ocean cooling through an enhancement of the eddy field and resultant eddy heat divergence. The transient cooling extends over multiple decades while the mean flow adjusts to balance the faster eddy response. This wind‐driven cooling mechanism has not been captured by coarse resolution models with fixed eddy parameterizations and is a possible candidate for the recent cooling observed in the Southern Ocean.
Agulhas ring formation as a barotropic instability of the retroflection
Authors: Weijer Wilbert , Zharkov Volodymyr , Nof Doron , Dijkstra Henk A. , de Ruijter Wilhelmus P. M. , van Scheltinga Arjen Terwisscha , Wubs Fred
Published: October 2013

Agulhas Leakage is an important link in the global ocean circulation, as it transfers a significant volume of relatively warm and salty water from the Indian Ocean to the Atlantic Ocean. The main route of this transfer is through the shedding of large Agulhas rings from the Agulhas retroflection. In this paper we study the dynamics of the ring formation process by analyzing the stability of the Indian/Atlantic supergyre in a reduced gravity model. We show that the ring‒shedding process results from a barotropic instability of the steady circulation in the Agulhas retroflection region. The destabilizing mode appears to be linked to a Rossby basin mode of the combined South Indian/Atlantic basin, which is localized in the retroflection region by the background flow.
Tasman Leakage of intermediate waters as inferred from Argo floats
Authors: Rosell‐Fieschi Miquel , Rintoul Stephen R. , Gourrion Jeröme , Pelegrí Josep L.
Published: October 2013

We use Argo float trajectories to infer ocean current velocity at the sea surface and 1000 dbar near Australia. The East Australian Current flows southward along the east coast of Australia at both surface and intermediate levels, but only the intermediate waters leak round the southern tip of Tasmania and cross the Great Australian Bight. We calculate the transport of Antarctic Intermediate Water (AAIW) between the southern Australian coast and the Antarctic Circumpolar Current (ACC) as the velocity at 1000 dbar times the layer thickness. Between March 2006 and December 2012, the Eulerian AAIW transport through 147°E ranges between 0 and 12.0 sverdrup (Sv). The mean Tasman Leakage of intermediate waters from the Pacific Ocean into the Indian Ocean, obtained using all Argo data until March 2013, is 3.8 ± 1.3 Sv. The mean intermediate water transport into the Indian Ocean through 115°E increases to 5.2 ± 1.8 Sv due to contributions from the westward recirculation of ACC waters.
Tide‐induced microseismicity in the Mertz glacier grounding area, East Antarctica
Authors: Barruol Guilhem , Cordier Emmanuel , Bascou Jérôme , Fontaine Fabrice R. , Legrésy Benoit , Lescarmontier Lydie
Published: October 2013

The deployment of a seismic network along the Adélie and George V coasts in East Antarctica during the period 2009–2012 provides the opportunity to monitor cryoseismic activity and to obtain new insights on the relationship between tidal cycles and coastal glacier dynamics. Here we focus on records from a seismometer located on a rocky outcrop in the vicinity of the grounding line of the 35 km broad Mertz glacier, a major outflow of this region. We detect numerous icequakes (50,000 events within 10 months and up to 100 events/h) and demonstrate their clear tidal modulation. We suggest that they result from ice friction and fracturing around the rocky peak and from the glacier flexure in response to the falling and rising tides at its grounding area. We propose that such icequake monitoring could be used as a climate proxy since grounding lines are subject to migrate with sea level changes.
Natural aerosol–climate feedbacks suppressed by anthropogenic aerosol
Authors: Spracklen D. V. , Rap A.
Published: October 2013

The natural environment is an important source of atmospheric aerosol such as dust, sea spray, and wildfire smoke. Climate controls many of these natural aerosol sources, which, in turn, can alter climate through changing the properties of clouds and the Earth's radiative balance. However, the Earth's atmosphere is now heavily modified by anthropogenic pollution aerosol, but how this pollution may alter these natural aerosol–climate feedbacks has not been previously explored. Here we use a global aerosol microphysics model to analyze how anthropogenic aerosol alters one link within these feedbacks, namely, the sensitivity of cloud albedo to changes in natural aerosol. We demonstrate that anthropogenic aerosol in the Northern Hemisphere has halved the hemispheric mean cloud albedo radiative effect that occurs due to changes in natural aerosol emissions. Such a suppression has not occurred in the more pristine Southern Hemisphere.
Lightning attachment process involving connection of the downward negative leader to the lateral surface of the upward connecting leader
Authors: Lu Weitao , Chen Luwen , Ma Ying , Rakov V. A. , Gao Yan , Zhang Yang , Yin Qiyuan , Zhang Yijun
Published: October 2013

High‐speed video camera records, with a temporal resolution of 20 µs and a spatial resolution of 2.4 m per pixel, of a downward negative lightning flash that terminated on a 440 m high building are examined. The attachment process in this flash exhibited an unexpected behavior in that the downward leader tip connected to the lateral surface of the ~400 m upward connecting leader (UCL) below its tip. It appears that the effect of the downward leader on the UCL is significant, while the effect of the UCL on the downward leader is negligible, except for the final 80 µs preceding the beginning of the first return stroke. The ratio of speeds of the downward leader and the UCL tends to decrease with time, ranging from 1.8 to 0.12, although the lower 80–100 m or so of the UCL were too faint to allow speed measurements.
Local time, seasonal, and solar cycle dependency of longitudinal variations of TEC along the crest of EIA over India
Authors: Sunda Surendra , Vyas B. M.
Published: October 2013

The global wave number 4 structure in the Indian longitudinal region spanning from ~70 to 95°E forming the upward slope of the peak in the total electron content (TEC) are reported along the crest of equatorial ionization anomaly (EIA). The continuous and simultaneous measurements from five GPS stations of GPS Aided Geo Augmented Navigation (GAGAN) network are used in this study. The long‐term database (2004–2012) is utilized for examining the local time, seasonal, and solar cycle dependency on the longitudinal variations of TEC. Our results confirm the existence of longitudinal variations of TEC in accordance with wave number 4 longitudinal structure including its strength. The results suggest that these variations, in general, start to develop at ~09 LT, achieve maximum strength at 12–15 LT, and decay thereafter, the decay rate depending on the season. They are more pronounced in equinoctial season followed by summer and winter. The longitudinal variations persist beyond midnight in equinox seasons, whereas in winter, they are conspicuously absent. Interestingly, they also exhibit significant solar cycle dependence in the solstices, whereas in the equinoxes, they are independent of solar activity. The comparison of crest‐to‐trough ratio (CTR) in the eastern (92°E) and western (72°E) extreme longitudes reveals higher CTR on the eastern side than over the western extreme, suggesting the role of nonmigrating tides in modulating the ExB vertical drift and the consequential EIA crest formation.
Empirical modeling of plasma sheet pressure and three‐dimensional force‐balanced magnetospheric magnetic field structure: 2. Modeling
Authors: Yue Chao , Wang Chih‐Ping , Zaharia Sorin G. , Xing Xiaoyan , Lyons Larry
Published: October 2013

The magnetic field configuration is crucial to plasma sheet dynamics and magnetosphere‐ionosphere coupling. In this study we established 3‐D force‐balanced magnetic fields and investigated configuration changes with Kp and solar wind dynamic pressure (PSW). Pressure distributions from the empirical model developed in Wang et al. (2013) were used for obtaining the force‐balanced field. Based on our model results, we found that (1) higher PSW mainly enhances pressure in the tail plasma sheet, while larger convection during higher Kp drives plasma sheet further earthward, resulting in a pressure increase closer to the Earth; (2) comparing with the magnetic field changes due to increasing PSW, the Kp associated pressure enhancement causes the azimuthal current density (Jϕ) peak and field‐aligned currents (FACs) to move deeper earthward, the magnetic field to decrease further near Earth but increase more in the tail, and field lines to stretch more significantly; (3) as Kp and PSW change, the whole plasma sheet remains stable to interchange instability but may be ballooning unstable in the midnight region at X between −15 and −10 RE; (4) the force‐balanced configurations are characteristically different from the non‐force‐balanced Tsyganenko 89 (T89) magnetic field. A region of positive dBz/dz in the near‐Earth region, which has been observed, is seen in our field but not in T89. On the other hand, a local equatorial Bz minimum is predicted by T89 but not by our model. Jφ bifurcation appears in the near‐Earth region as a result of our Jφ configuration being approximately aligned with field lines, while the T89 Jφ everywhere decreases monotonically with increasing Z by construction.
An empirical model for the location and occurrence rate of near‐Earth magnetotail reconnection
Authors: Genestreti K. J. , Fuselier S. A. , Goldstein J. , Nagai T.
Published: October 2013

We introduce an empirical model for the location and rate of occurrence of magnetic reconnection in the near‐Earth magnetotail. The model is constructed using Geotail data, including the set of diffusion region and fast tailward flow events identified in Nagai et al. (2005). Events are arranged by their XGSM location. The event occurrence profile is normalized by the time spent by Geotail within a distance d of the modeled neutral sheet. To locate the neutral sheet, we use the empirical model of Fairfield (1980). We organize our data via a coordinate system that conforms to the Fairfield neutral sheet model. In this new coordinate system, we calculate the deviation of physical neutral sheet crossings from their Fairfield‐model‐predicted locations. We equate d to constant multiples of this standard deviation (0.5 RE, 2 RE, and 5 RE). Using these values, we find that our deduced rate of occurrence of reconnection events has a magnitude consistent with those from similar calculations found in the existing literature. We then use our empirical model to analyze the predicted ephemeris for the Magnetospheric Multiscale (MMS) mission. We predict that during its upcoming near‐tail survey phase, MMS will observe between nine and four diffusion region events (nominal estimate of 7), and between 57 and 31 fast tailward flow events (nominal estimate of 47). Because of the restrictive nature of the criteria used to identify diffusion region events, we emphasize that the number of predicted events that we calculate represents a conservative estimate.
Suppression of slip and rupture velocity increased by thermal pressurization: Effect of dilatancy
Authors: Urata Yumi , Kuge Keiko , Kase Yuko
Published: October 2013

We investigated the effect of dilatancy on dynamic rupture propagation on a fault where thermal pressurization (TP) is in effect, taking into account permeability varying with porosity; the study is based on three‐dimensional (3‐D) numerical simulations of spontaneous ruptures obeying a slip‐weakening friction law and Coulomb failure criterion. The effects of dilatancy on dynamic ruptures interacting with TP have been often investigated in one‐ or two‐dimensional numerical simulations. The sole 3‐D numerical simulation gave attention only to the behavior at a single point on a fault. Moreover, with the sole exception based on a single‐degree‐freedom spring‐slider model, the previous simulations including dilatancy and TP have not considered changes in hydraulic diffusivity. However, the hydraulic diffusivity, which strongly affects TP, can vary as a power of porosity. In this study, we apply a power law relationship between permeability and porosity. We consider both reversible and irreversible changes in porosity, assuming that the irreversible change is proportional to the slip rate and dilatancy coefficient ɛ. Our numerical simulations suggest that the effects of dilatancy can suppress slip and rupture velocity increased by TP. The results reveal that the amount of slip on the fault decreases with increasing ɛ or exponent of the power law, and the rupture velocity is predominantly suppressed by ɛ. This was observed regardless of whether the applied stresses were high or low. The deficit of the final slip in relation to ɛ can be smaller as the fault size is larger.
Improved cirrus simulations in a general circulation model using CARMA sectional microphysics
Authors: Bardeen C. G. , Gettelman A. , Jensen E. J. , Heymsfield A. , Conley A. J. , Delanoë J. , Deng M. , Toon O. B.
Published: October 2013

We have developed a new cirrus model incorporating sectional ice microphysics from the Community Aerosol and Radiation Model for Atmospheres (CARMA) in the latest version of NCAR's Community Atmosphere Model (CAM5). Comparisons with DARDAR and 2C‐ICE show that CAM5/CARMA improves cloud fraction, ice water content, and ice water path compared to the standard CAM5. Prognostic snow in CAM5/CARMA increases overall ice mass and results in a melting layer at ~4 km in the tropics that is largely absent in CAM5. Subgrid scale supersaturation following Wilson and Ballard (1999) improves ice mass and relative humidity. Increased middle and upper tropospheric condensate in CAM5/CARMA requires a reduction in low‐level cloud for energy balance, resulting in a 3.1 W m−2 improvement in shortwave cloud forcing and a 3.8 W m−2 improvement in downwelling shortwave flux at the surface compared to CAM5 and Clouds and Earth's Radiant Energy Systems (CERES). Total and clear‐sky longwave upwelling flux at the top are improved in CAM5/CARMA by 1.0 and 2.6 W m−2, respectively. CAM has a 2–3 K cold bias at the tropical tropopause mostly from the prescribed ozone file. Correction of the prescribed ozone or nudging the CAM5/CARMA model to GEOS5‐DAS meteorology yields tropical tropopause temperatures and water vapor that agree with the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) and the Microwave Limb Sounder (MLS). CAM5 relative humidity appears to be too large resulting in a +1.5 ppmv water vapor bias at the tropical tropopause when using GEOS5‐DAS meteorology. In CAM5/CARMA, 75% of the cloud ice mass originates from ice particles detrained from convection compared to 25% from in situ nucleation.
Long‐term trends of biogenic sulfur aerosol and its relationship with sea surface temperature in Arctic Finland
Authors: Laing James R. , Hopke Philip K. , Hopke Eleanor F. , Husain Liaquat , Dutkiewicz Vincent A. , Paatero Jussi , Viisanen Yrjö
Published: October 2013

Forty‐seven years of week‐long total suspended particle samples from Kevo Finland were analyzed for methane sulfonic acid (MSA) and sulfate. Kevo is located 350 km north of the Arctic Circle. MSA and non‐sea‐salt sulfate (NSS‐SO4) showed clear seasonal trends. MSA peaks from May to July, coinciding with warmer waters and increased biogenic activity in the surrounding seas. NSS‐SO4 peaks in March with a minimum during the summer, the typical pattern for Arctic haze. MSA concentrations were found to be positively correlated (p < 0.001) with sea surface temperature anomalies in the surrounding seas. MSA showed a trend of 0.405 ng/m3/yr (0.680%/yr) for June and July. NSS‐SO4 concentrations at Kevo declined dramatically in the early 1990s, probably as a result of the collapse of the Soviet Union. The decline has continued since the mid‐1990s.
Suomi NPP VIIRS sensor data record verification, validation, and long‐term performance monitoring
Authors: Cao Changyong , Xiong Jack , Blonski Slawomir , Liu Quanhua , Uprety Sirish , Shao Xi , Bai Yan , Weng Fuzhong
Published: October 2013

The successful launch of the Suomi National Polar‐orbiting Partnership Satellite on 28 October 2011 with the key instrument Visible Infrared Imaging Radiometer Suite signifies a new era of moderate‐resolution imaging capabilities following the legacy of AVHRR and Moderate‐Resolution Imaging Spectroradiometer (MODIS). After a year and half of calibration and validation, the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument is performing very well. By early 2013, the sensor data records have achieved provisional maturity status and have been used in the routine production of more than 20 environmental data records by users worldwide. Based on comparisons with MODIS, the VIIRS reflective solar band radiometric uncertainties are now comparable in reflectance to that of MODIS Collection 6 equivalent bands (within 2%) although radiance differences could be larger for several bands, while an agreement on the order of 0.1 K has also been achieved for the thermal emissive bands, except for bands with significant spectral differences or certain bands at extreme temperatures (below 200 K or above 343 K). The degradation in the VIIRS rotating telescope assembly mirrors is gradually leveling off after reaching ~30% and thus far has limited impact on instrument performance and products. Environmental data record users are generally satisfied with the VIIRS data quality which meets the product requirements. While the specific technical details are documented in other papers in this special issue and in Cao et al. (2013a), this paper focuses on the major findings of VIIRS calibration and validation since launch, radiometric performance validation, and uncertainties, as well as lessons learned.
Inverse modeling of flow tomography experiments in fractured media
Authors: Klepikova Maria V. , Le Borgne Tanguy , Bour Olivier , de Dreuzy Jean‐Raynald
Published: October 2013

The accurate characterization of the location, hydraulic properties, and connectivity of major fracture zones is essential to model flow and solute transport in fractured media. Cross‐borehole flowmeter tests, which consist of measuring changes in vertical borehole flows when pumping a neighboring borehole, were shown to be an efficient technique to provide information on the properties of the flow zones that connect borehole pairs. The interpretation of such experiments may, however, be quite uncertain when multiple connections exist. In this study, we explore the potential of flow tomography (i.e., sequential cross‐borehole flowmeter tests) for characterizing aquifer heterogeneity. We propose a framework for inverting flow and drawdown data to infer fracture connectivity and transmissivities. We demonstrate that successively exchanging the roles of pumping and observation boreholes improves the quality of available information and reduces the under‐determination of the problem. The inverse method is validated for several synthetic flow scenarios. It is shown to provide a good estimation of connectivity patterns and transmissivities of main flow paths. It also allows the estimation of the transmissivity of fractures that connect the flow paths but do not cross the boreholes, although the associated uncertainty may be high for some geometries.
Competing controls on groundwater oxygen concentrations revealed in multidecadal time series from riverbank filtration sites
Authors: Figura Simon , Livingstone David M. , Kipfer Rolf
Published: October 2013

Dissolved oxygen (DO) is an important indicator of groundwater quality, but long time series of groundwater DO concentration are rare. Here we describe and analyze multidecadal time series of groundwater DO data from five Swiss aquifers that are recharged by riverbank filtration (RBF), and relate temporal features of the DO time series to potential forcing factors. Features found in the DO time series include long‐term decreases and abrupt increases. Some features occur simultaneously in hydrologically unconnected aquifers, suggesting that external forcing partially determines DO concentrations at RBF sites. The data indicate that: (i) the DO concentration in the losing river is not a critical determinant of groundwater DO concentration; (ii) increasing river‐water and groundwater temperatures, by affecting both the physical solubility of oxygen and DO consumption in the hyporheic zone, probably cause the long‐term decline in DO concentration observed in most aquifers investigated; and (iii) a complex interaction between hydrological factors such as groundwater pumping rate and river discharge results in abrupt changes in groundwater DO concentration. Climate models predict higher temperatures and more frequent flood events in central Europe, implying that groundwater DO concentrations at many RBF sites will continue to decrease in the long term, but that irregular high‐discharge events, by scouring and unclogging riverbeds, will probably prevent the occurrence of long periods of hypoxia. Nonetheless, the risk of short periods of hypoxia at RBF sites is likely to increase.