bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of Body Composition in Male Patients during Chronic Obstructive Pulmonary Disease (COPD) Development
Authors: Makarevich Aliaksandr , Lemiasheuskaya Sviatlana
Published: November 2015

Introduction: The various distribution of fat mass (FM) and lean mass (LM) during COPD development is not yet researched. Materials and Methods: 82 male patients (40–67 years) with acute exacerbation of COPD and 19 comparable healthy males (the control group) were examined by dual-energy X-ray absorptiometry. The patients were divided into 3 groups according to COPD severity: 1st—19 (GOLD I stage); 2nd—43 (GOLD II) and 3rd—20 (GOLD III). Results: The patients of 3rd group had lower indices of FM, LM, bone mineral component (BMC) vs. the control and 1st, 2nd groups. A significant increase in FM share was noted in android and gynoid regions, trunk, legs and arms in 2nd groups vs. the control with the decline of these parameters in the 3rd group below the control level. A greater proportion of FM in 1st and 2nd groups was distributed in android and trunk regions vs. the control. TNF-α and leptin levels were significantly increased by 12%, 15% 17% and by 18%, 75%, 79% respectively in 1st, 2nd, 3rd groups vs. the control, while free testosterone level was lower in these groups vs. the control (by 28%, 30% and 47% respectively; p < 0.05). Conclusions: Body mass index (BMI) was within the control range in mild-moderate COPD patients in spite of LM, FM and BMC changes. The level of LM and BMC was decreased during COPD progression, while FM was increased in mild-moderate COPD and then it was decreased in severe COPD.
Ensino de programação para Olimpíada Brasileira de Informática
Authors: Santos Aellison C. T. dos , Monteiro José A. , Machado Karla Cristina T. , Lins Paulo R. Branco , Ramos Thaís De Almeida R. , Batista Leonardo V.
Published: November 2015

Com o crescimento vertiginoso do uso da tecnologia, o conhecimento em computação e em programação vem se tornando um elemento vital na sociedade, porém muitos jovens possuem uma ideia equivocada a respeito deste conhecimento, o que reflete na elevada taxa de evasão dos cursos relacionados à área da computação. Este artigo apresenta um projeto de extensão que tem como objetivo ensinar programação para alunos do ensino médio, capacitandoos à participar da Olimpíada Brasileira de Informática, evento que permite que os alunos conheçam mais a fundo a Ciência da Computação. Os alunos participantes demonstraram grande satisfação com os cursos, possuindo interesse na participação de edições posteriores dos mesmos.
Robótica Educacional em Prol do Ensino de Matemática
Authors: Barbosa Fernando da C. , Alexandre Mário L. , Alves Deive B. , Menezes Douglas C. de , Campos Gabriel L. , Nakamura Ygor S. N. , S. Junior Arlindo J. de , Lopes Carlos R.
Published: November 2015

Este relato expõe como construímos momentos de práticas e reflexões educativas, que relacionaram conteúdos de matemática com a Robótica Educacional utilizando kits da LEGO, a partir da necessidade de obter dados precisos na programação de um robô para execução de giros. Essa necessidade culminou em um problema que surgiu em um trabalho com alunos do Ensino Médio resultando em um aplicativo para futuras programações de robôs. Essa experiência se configurou como um espaço de relação entre os conteúdos de matemática e problemas reais, desse modo, apresentamos em nossas considerações finais a relação entre o que foi desenvolvido e a Modelagem Matemática.
Informática Aplicada à Educação nas Escolas Públicas: Estudos e Perspectivas de Parcerias com o Instituto Federal de Goiás, Campus Inhumas
Authors: Silveira Junior Carlos R. da , Araújo Wederson X. de , Barra Alex S. B. , Vieira Marcos A.
Published: November 2015

A inserção da informática no ambiente escolar faz-se necessária, pois permite o acesso do estudante aos recursos tecnológicos, vislumbrando o conhecimento de forma mais criativa, integrativa e motivadora, devendo ser disponível nas escolas. No Brasil o PROINFO tem o papel de introduzir tecnologia de informação e comunicação nas escolas. No entanto a realidade é diferente: laboratórios sucateados, professores sem formação e alunos desmotivados. Este artigo refere-se a estudos estatísticos de dados coletados, realizados com questionários e entrevista, nas escolas públicas estaduais na Região de Inhumas, estado de Goiás, que foram contemplados pelo Programa Nacional de Tecnologia Educacional. Através dos resultados pode-se pensar em alternativas de parcerias com o Instituto Federal de Goiás, Campus Inhumas, para auxiliar na melhoria do processo ensino de Informática na Educação.
Utilizando o Scratch como ferramenta de apoio para desenvolver o raciocínio lógico das crianças do ensino básico de uma forma multidisciplinar
Authors: Batista Esteic Janaina S. , Castro Jr. Amaury A. , Bogarim Cintia Adriana C. , Larrea Andreia A.
Published: November 2015

Este trabalho tem como objetivo apresentar a oficina sobre a ferramenta Scratch para professores das salas de tecnologia das escolas de uma cidade, para que possa ser utilizada em sala de aula pelos professores, uma vez que permite ser utilizado em diferentes disciplinas, e ensinar conceitos de programação de forma quase inconsciente. Será apresentado como o Scratch favorece o desenvolvimento do raciocínio lógico das crianças, que pode resultar em melhores notas destes alunos em provas da OBI e OBR por exemplo, que exigem essa capacidade de resolver problemas e desafios.
Iniciativas de Inclusão Digital em escolas públicas por meio de uma revisão sistemática da literatura
Authors: Mendonça Patricia Graziely Antunes de , Maciel Cristiano , Alonso Katia Morosov
Published: November 2015

O artigo identifica estudos que tratam de projetos de inclusão digital induzida, oriundos do Governo Federal, executados em escolas públicas brasileiras. Utiliza-se da metodologia de revisão sistemática, executando a pesquisa em etapas bem definidas com o apoio da ferramenta StArt para aplicação do protocolo de pesquisa. Assim, este estudo identifica e seleciona trabalhos que contemplam os projetos ProUCA e Proinfo, e, detecta a dificuldade com a qual os projetos estão sendo implantados nas escolas envolvidas.
Pensamento Computacional: transformando ideias em jogos digitais usando o Scratch
Authors: Rodriguez Carla Lopes , Zem-Lopes Aparecida Maria , Marques Leonardo , Isotani Seiji
Published: November 2015

A integração das Tecnologias de Informação e Comunicação à rotina das escolas se faz hoje necessária, uma vez que possuem potencial para transformar o processo de ensino e aprendizagem e podem contribuir para o desenvolvimento de diversas habilidades nos jovens estudantes como, por exemplo, o raciocínio lógico e a capacidade de resolução de problemas. Nesse sentido, esse trabalho apresenta a experiência vivenciada em um projeto, realizado no âmbito de um programa de Pré-Iniciação Científica, cujo objetivo principal foi desenvolver noções básicas do "pensamento computacional", junto aos alunos do primeiro ano do ensino médio de uma escola pública, por meio dos recursos do Scratch.
Monitoring on CO2 Migration in a Tight Oil Reservoir during CO2-EOR Process
Authors: Ren Bo , Ren Shaoran , Zhang Liang , Huang Haidong , Chen Guoli , Zhang Hua
Published: November 2015

Monitoring CO2 migration in the oil reservoir is one of the most important MVA (monitoring, verification and accounting) activities. A systematic monitoring program has been deployed to track the movement of CO2 in a tight oil reservoir during a CCS-EOR project in the Jilin oilfield, China. CO2 separated from a nearby natural gas reservoir (15–30 mole% CO2) has been injected into the northern part of H59 oil block with permeability and porosity of 3.5mD and 12.7%, respectively. A microseismic monitoring program has been implemented to map the CO2 flow anisotropy and estimate its sweeping conformance profile. Gas tracer testing has also been conducted to examine the inter-well connectivity. The composition of produced gas has been analyzed in a real-time mode to monitor the dynamic response of different production wells along with the microseismic. In applying the microseismic technique, the open and closure of the pre-existing natural fractures were well corresponding with the variation of CO2 injection pressure. Higher injection pressure can induce the re-open of the pre-existing natural fractures, and the CO2 flow pattern induced by the fracture network become less anisotropic. And the microseismic events detected were consistent with the orientation of the natural fractures and the stress distribution in the reservoir. However, for the lower injection pressure, the inversed microseismic profiles clearly show the preferential CO2 flows and their anisotropy in different well groups, which are mainly dominated by the pressure gradient and the heterogeneity of reservoir permeability. And the detected micro-seismicity is caused by stress gradients induced by production and injection gradient, rather than the local natural fractures. The sweeping profiles of CO2 obtained from the microseismic were in good agreement with the temporal change of the produced CO2 rate from production wells as well as the permeability characterization of the reservoir. The mapped preferential flow direction and sweeping profile of CO2 from microseismic provides a good prediction for the breakthrough of CO2 and its extent, which is useful for conformance control and injection optimization. Also, the microseismic test provides a very good indicator of CO2 leakage from the oil reservoir, which is a cost-effective technique in ensuring long and safe storage of CO2 in the subsurface.
The Pore Scale Description of Carbon Dioxide Storage into High Asphaltene Content Reservoirs
Authors: Coelho Raphael , Hascakir Berna
Published: November 2015

The knowledge of how CO2 interacts with reservoir fluids and rock is essential for effective and reliable CO2 storage. This work investigates CO2 storage in unconventional oil reservoirs with high asphaltene content and explains the CO2 storage mechanism in pore-scale. Considering that asphaltenes are insoluble in CO2, asphaltene precipitation is induced during CO2 injection, controlling CO2 solubility and capillary trapping mechanisms. In this study, CO2-oil interaction is examined through core flooding experiments in a high asphaltene content (34.3 wt%) Canadian bitumen sample with 8.8º API. To study how irreversible clay-asphaltene interaction affects CO2 capillary trapping, the reservoir rock is prepared with and without clay addition. The role of CO2 injection rate on solubility trapping with experiments at varying injection flow rates. Displaced fluids and postmortem samples are subjected to several analyses to observe the CO2 storage mechanisms in pore scale due to CO2-asphaltene and CO2-clay-asphaltene interactions. It was found that CO2-clay-asphaltene interaction may favor CO2 capillary trapping into high asphaltene content reservoirs. Reservoir clays play important roles in porosity and permeability reduction due to clay interactions with asphaltenes. The low CO2 flow rate was found to favor solubility trapping. Therefore, our results suggest that the presence of clays and the CO2 injection rate are critical parameters controlling the effectiveness of CO2 storage in high asphaltene content reservoirs.

Introduction

Underground carbon dioxide (CO2) storage projects usually target the depleted light oil and natural gas fields due to operational expertise, favorable geological features, and existence of infrastructure [1; 2]. However, as CO2 emissions are projected to increase in the next 35 years [3], other storage alternatives are required to mitigate environmental impacts. In this context, CO2 storage in unconventional oil reservoirs with low API gravity may be an attractive candidate on the short to medium term [4; 5].

These low API gravity oils usually have high asphaltene content, which can represent up to 45.3 wt% of the crude oil [6]. CO2 injection can cause asphaltenes precipitate in the pore space as CO2 is insoluble in asphaltenes [7; 8]. Therefore, the effectiveness of CO2 microscopic storage mechanisms will be affected, particularly for capillary (or residual) and solubility trapping.
Se désaffilier pour mieux s’affilier ? Complexité du cheminement d’anciens membres de gang de rue d’origine haïtienne
Authors: Lacroix1 Olivier , Gilbert Sophie
Published: November 2015

La désaffiliation vis-à-vis des gangs de rue correspond à un cheminement complexe, long et sinueux. Les processus psychiques impliqués sont présentés dans cet article à travers les résultats d’une recherche qualitative d’orientation psychodynamique. Trois anciens membres de gang d’origine haïtienne ont été recrutés et ont participé à des récits de vie. L’analyse des entrevues a été élaborée à l’aide de catégories conceptualisantes. Intégrés dans une métaphore globale, nos résultats permettent de discuter trois dimensions principales et interreliées du processus de sortie : l’investissement des rencontres, l’évolution du récit et les étapes psychiques du passage par les gangs de rue. Ces résultats soutiennent des pistes d’intervention novatrices auprès de cette population.
Do intertidal flats ever reach equilibrium?
Authors: Maan D. C. , van Prooijen B. C. , Wang Z. B. , De Vriend H. J.
Published: November 2015

Various studies have identified a strong relation between the hydrodynamic forces and the equilibrium profile for intertidal flats. A thorough understanding of the interplay between the hydrodynamic forces and the morphology, however, concerns more than the equilibrium state alone. We study the basic processes and feedback mechanisms underlying the long‐term behavior of the intertidal system, restricting ourselves to unvegetated intertidal flats that are controlled by cross‐shore tidal currents and wind waves and applying a 1‐D cross‐shore morphodynamic model. The results indicate that by an adjustment of the profile slope and shape, an initial imbalance between deposition and erosion is minimized within a few decades. What follows is a state of long‐term seaward progradation or landward retreat of the intertidal flat, in which the cross‐shore profile shape is largely maintained and the imbalance between deposition and erosion is not further reduced. These long‐term trends can be explained by positive feedbacks from the morphology onto the hydrodynamic forces over the flat: initial accretion (erosion) decreases (increases) the shear stresses over the flat, which induces further accretion (erosion). This implies that a static equilibrium state cannot exist; the flat either builds out or retreats. The modeled behavior is in accordance with observations in the Yangtze Estuary. To treat these unbalanced systems with a one‐dimensional numerical model, we propose a moving (Lagrangian) framework in which a stable cross‐sectional shape and progradation speed can be derived for growing tidal flats, as a function of the wave climate and the sediment concentration in deeper water.
Mechanisms and predictability of multiyear ecosystem variability in the North Pacific
Authors: Chikamoto Megumi O. , Timmermann Axel , Chikamoto Yoshimitsu , Tokinaga Hiroki , Harada Naomi
Published: November 2015

Aleutian Low variations provide vorticity, buoyancy, and heat‐flux forcing to the North Pacific Ocean, which in turn cause changes in ocean circulation, mixed layer characteristics and sea ice coverage. In this process the white noise atmospheric characteristics are integrated dynamically and thermodynamically to generate red noise ocean spectra. Using the Community Earth System Model (version 1.0.3) we study the resulting biogeochemical and ecosystem responses in the North Pacific. We find that ocean dynamical variables have an impact on the tendencies of key nutrients and biological production, which leads to a further reddening of biogeochemical spectra resulting in potential predictability on time scales of 2–4 years. However, this low‐pass filtering does not apply to all biogeochemical variables and is regionally dependent. It is shown that phytoplankton biomass in the Central North Pacific adjusts to the much shorter‐term variability associated with changes in mixed layer depth, light availability, and zooplankton grazing, thus limiting the predictability of phytoplankton anomalies to about 1 year. In the eastern North Pacific the slow advection of anomalous nutrient concentrations leads to longer persistence of phytoplankton variability and increased potential predictability of up to 3 years.
Ammonia and nitrite oxidation in the Eastern Tropical North Pacific
Authors: Peng Xuefeng , Fuchsman Clara A. , Jayakumar Amal , Oleynik Sergey , Martens‐Habbena Willm , Devol Allan H. , Ward Bess B.
Published: November 2015

Nitrification plays a key role in the marine nitrogen (N) cycle, including in oceanic oxygen minimum zones (OMZs), which are hot spots for denitrification and anaerobic ammonia oxidation (anammox). Recent evidence suggests that nitrification links the source (remineralized organic matter) and sink (denitrification and anammox) of fixed N directly in the steep oxycline in the OMZs. We performed shipboard incubations with 15N tracers to characterize the depth distribution of nitrification in the Eastern Tropical North Pacific (ETNP). Additional experiments were conducted to investigate photoinhibition. Allylthiourea (ATU) was used to distinguish the contribution of archaeal and bacterial ammonia oxidation. The abundance of archaeal and β‐proteobacterial ammonia monooxygenase gene subunit A (amoA) was determined by quantitative polymerase chain reaction. The rates of ammonia and nitrite oxidation showed distinct subsurface maxima, with the latter slightly deeper than the former. The ammonia oxidation maximum coincided with the primary nitrite concentration maximum, archaeal amoA gene maximum, and the subsurface nitrous oxide maximum. Negligible rates of ammonia oxidation were found at anoxic depths, where high rates of nitrite oxidation were measured. Archaeal amoA gene abundance was generally 1 to 2 orders of magnitude higher than bacterial amoA gene abundance, and inhibition of ammonia‐oxidizing bacteria with 10 μM ATU did not affect ammonia oxidation rates, indicating the dominance of archaea in ammonia oxidation. These results depict highly dynamic activities of ammonia and nitrite oxidation in the oxycline of the ETNP OMZ.
Observations of wind stress direction during Typhoon Chaba (2010)
Authors: Potter Henry , Collins Clarence O. , Drennan William M. , Graber Hans C.
Published: November 2015

Direct flux measurements of stress direction taken at the ocean surface during Typhoon Chaba (2010) over 3 days are examined for wind speeds between 12 and 26.5 m s−1. Results show stress deviated up to 35° from the wind direction and resided predominantly between the wind and peak wave directions in both bimodal and unimodal seas. Off‐wind stress angle was most pronounced in Chaba's wake where wind sea and swell created an apparent unimodal system with narrow directional spread. These conditions lasted 2 days during which the stress direction was midway between the wind and wave directions. The implications for tropical cyclone forecasting are discussed.
Kinetic Alfvén waves and particle response associated with a shock‐induced, global ULF perturbation of the terrestrial magnetosphere
Authors: Malaspina David M. , Claudepierre Seth G. , Takahashi Kazue , Jaynes Allison N. , Elkington Scot R. , Ergun Robert E. , Wygant John R. , Reeves Geoff D. , Kletzing Craig A.
Published: November 2015

On 2 October 2013, the arrival of an interplanetary shock compressed the Earth's magnetosphere and triggered a global ULF (ultra low frequency) oscillation. The Van Allen Probe B spacecraft observed this large‐amplitude ULF wave in situ with both magnetic and electric field data. Broadband waves up to approximately 100 Hz were observed in conjunction with, and modulated by, this ULF wave. Detailed analysis of fields and particle data reveals that these broadband waves are Doppler‐shifted kinetic Alfvén waves. This event suggests that magnetospheric compression by interplanetary shocks can induce abrupt generation of kinetic Alfvén waves over large portions of the inner magnetosphere, potentially driving previously unconsidered wave‐particle interactions throughout the inner magnetosphere during the initial response of the magnetosphere to shock impacts.
The competition of electron and ion heating during magnetic reconnection
Authors: Haggerty C. C. , Shay M. A. , Drake J. F. , Phan T. D. , McHugh C. T.
Published: November 2015

The physical processes that control the partition of released magnetic energy between electrons and ions during reconnection is explored through particle‐in‐cell simulations and analytical techniques. We demonstrate that the development of a large‐scale parallel electric field and its associated potential controls the relative heating of electrons and ions. The potential develops to restrain heated exhaust electrons and enhances their heating by confining electrons in the region where magnetic energy is released. Simultaneously, the potential slows ions entering the exhaust below the Alfvénic speed expected from the traditional counterstreaming picture of ion heating. Unexpectedly, the magnitude of the potential and therefore the relative partition of energy between electrons and ions is not a constant but rather depends on the upstream parameters and specifically the upstream electron normalized temperature (electron beta). These findings suggest that the fraction of magnetic energy converted into the total thermal energy may be independent of upstream parameters.
Acoustically induced slip in sheared granular layers: Application to dynamic earthquake triggering
Authors: Ferdowsi Behrooz , Griffa Michele , Guyer Robert A. , Johnson Paul A. , Marone Chris , Carmeliet Jan
Published: November 2015

A fundamental mystery in earthquake physics is “how can an earthquake be triggered by distant seismic sources?” Here we use discrete element method simulations of a granular layer, during stick slip, that is subject to transient vibrational excitation to gain further insight into the physics of dynamic earthquake triggering. Using Coulomb friction law for grains interaction, we observe delayed triggering of slip in the granular gouge. We find that at a critical vibrational amplitude (strain) there is an abrupt transition from negligible time‐advanced slip (clock advance) to full clock advance; i.e., transient vibration and triggered slip are simultaneous. The critical strain is of order 10−6, similar to observations in the laboratory and in Earth. The transition is related to frictional weakening of the granular layer due to a dramatic decrease in coordination number and the weakening of the contact force network. Associated with this frictional weakening is a pronounced decrease in the elastic modulus of the layer. The study has important implications for mechanisms of triggered earthquakes and induced seismic events and points out the underlying processes in response of the fault gouge to dynamic transient stresses.
Observations of runup and energy flux on a low‐slope beach with high‐energy, long‐period ocean swell
Authors: Fiedler Julia W. , Brodie Katherine L. , McNinch Jesse E. , Guza Robert T.
Published: November 2015

The transformation of surface gravity waves from 11 m depth to runup was observed on the low‐sloped (1/80) Agate Beach, Oregon, with a cross‐shore transect of current meters, pressure sensors, and a scanning lidar. Offshore wave heights H0 ranged from calm (0.5 m) to energetic (>7 m). Runup, measured with pressure sensors and a scanning lidar, increases linearly with (H0L0)1/2, with L0 the deep‐water wavelength of the spectral peak. Runup saturation, in which runup oscillations plateau despite further increases in (H0L0)1/2, is not observed. Infragravity wave shoaling and nonlinear energy exchanges with short waves are included in an infragravity wave energy balance. This balance closes for high‐infragravity frequencies (0.025–0.04 Hz) but not lower frequencies (0.003–0.025 Hz), possibly owing to unmodeled infragravity energy losses of wave breaking and/or bottom friction. Dissipative processes limit, but do not entirely damp, increases in runup excursions in response to increased incident wave forcing.
Influence of sediment cohesion on deltaic shoreline dynamics and bulk sediment retention: A laboratory study
Authors: Straub Kyle M. , Li Qi , Benson W. Matthew
Published: November 2015

While boundary and forcing conditions influence the average location of a shoreline in deltaic systems, internal morphodynamics can drive high‐magnitude deviations from the long‐term trend. Here we explore the role of sediment cohesion on these morphodynamics using physical experiments. Specifically, we explore the role of sediment cohesion on the scales of autogenic shoreline transgressions and regressions. Results indicate that sediment cohesion enhances the time and space scales associated with autogenic cycles of channel formation, elongation, and abandonment. In systems with high sediment cohesion, this cycle can drive shoreline transgressions that produce flooding surfaces in the resulting stratigraphy which could be confused with surfaces produced by increases in sea level rise or subsidence rates. Enhanced channelization resulting from sediment cohesion also increases the pumping of fine‐grained sediment into the marine realm, where it can bypass the delta foreset, thus decreasing total delta sediment retention rate.
Modeling aftershocks as a stretched exponential relaxation
Authors: Mignan A.
Published: November 2015

The decay rate of aftershocks has been modeled as a power law since the pioneering work of Omori in the late nineteenth century. Although other expressions have been proposed in recent decades to describe the temporal behavior of aftershocks, the number of model comparisons remains limited. After reviewing the aftershock models published from the late nineteenth century until today, I solely compare the power law, pure exponential and stretched exponential expressions defined in their simplest forms. By applying statistical methods recommended recently in applied mathematics, I show that all aftershock sequences tested in three regional earthquake catalogs (Southern and Northern California, Taiwan) and with three declustering techniques (nearest‐neighbor, second‐order moment, window methods) follow a stretched exponential instead of a power law. These results infer that aftershocks are due to a simple relaxation process, in accordance with most other relaxation processes observed in Nature.
Impact of the Atlantic meridional overturning circulation on the decadal variability of the Gulf Stream path and regional chlorophyll and nutrient concentrations
Authors: Sanchez‐Franks A. , Zhang R.
Published: November 2015

In this study, we show that the underlying physical driver for the decadal variability in the Gulf Stream (GS) path and the regional biogeochemical cycling is linked to the low frequency variability in the Atlantic meridional overturning circulation (AMOC). There is a significant anticorrelation between AMOC variations and the meridional shifts of the GS path at decadal time scale in both observations and two Earth system models (ESMs). The chlorophyll and nutrient concentrations in the GS region are found significantly correlated with the AMOC fingerprint and anticorrelated with the GS path at decadal time scale through coherent isopycnal changes in the GS front in the ESMs. Our results illustrate how changes in the large‐scale ocean circulation, such as AMOC, are teleconnected with regional decadal physical and biogeochemical variations near the North American east coast. Such linkages are useful for predicting future physical and biogeochemical variations in this region.
Tropical sources and sinks of carbonyl sulfide observed from space
Authors: Glatthor N. , Höpfner M. , Baker I. T. , Berry J. , Campbell J. E. , Kawa S. R. , Krysztofiak G. , Leyser A. , Sinnhuber B.‐M. , Stiller G. P. , Stinecipher J. , von Clarmann T.
Published: November 2015

According to current budget estimations the seasonal variation of carbonyl sulfide (COS) is governed by oceanic release and vegetation uptake. Its assimilation by plants is assumed to be similar to the photosynthetic uptake of CO2 but, contrary to the latter process, to be irreversible. Therefore, COS has been suggested as cotracer of the carbon cycle. Observations of COS, however, are sparse, especially in tropical regions. We use the comprehensive data set of spaceborne measurements of the Michelson Interferometer for Passive Atmospheric Sounding to analyze its global distribution. Two major features are observed in the tropical upper troposphere around 250 hPa: enhanced amounts over the western Pacific and the Maritime Continent, peaking around 550 parts per trillion by volume (pptv) in boreal summer, and a seasonally varying depletion of COS extending from tropical South America to Africa. The large‐scale COS depletion, which in austral summer amounts up to −40 pptv as compared to the rest of the respective latitude band, has not been observed before and reveals the seasonality of COS uptake through tropical vegetation. The observations can only be reproduced by global models, when a large vegetation uptake and a corresponding increase in oceanic emissions as proposed in several recent publications are assumed.
Quantifying changes in climate variability and extremes: Pitfalls and their overcoming
Authors: Sippel Sebastian , Zscheischler Jakob , Heimann Martin , Otto Friederike E. L. , Peters Jonas , Mahecha Miguel D.
Published: November 2015

Hot temperature extremes have increased substantially in frequency and magnitude over past decades. A widely used approach to quantify this phenomenon is standardizing temperature data relative to the local mean and variability of a reference period. Here we demonstrate that this conventional procedure leads to exaggerated estimates of increasing temperature variability and extremes. For example, the occurrence of “two‐sigma extremes” would be overestimated by 48.2% compared to a given reference period of 30 years with time‐invariant simulated Gaussian data. This corresponds to an increase from a 2.0% to 2.9% probability of such events. We derive an analytical correction revealing that these artifacts prevail in recent studies. Our analyses lead to a revision of earlier reports: For instance, we show that there is no evidence for a recent increase in normalized temperature variability. In conclusion, we provide an analytical pathway to describe changes in variability and extremes in climate observations and model simulations.
Disruption of groundwater systems by earthquakes
Authors: Liao Xin , Wang Chi‐Yuen , Liu Chun‐Ping
Published: November 2015

Earthquakes are known to enhance permeability at great distances, and this phenomenon may also disrupt groundwater systems by breaching the barrier between different reservoirs. Here we analyze the tidal response of water level in a deep (~4 km) well before and after the 2008 M7.9 Wenchuan earthquake to show that the earthquake not only changed the permeability but also altered the poroelastic properties of the groundwater system. Based on lithologic well logs and experimental data for rock properties, we interpret the change to reflect a coseismic breaching of aquitards bounding the aquifer, due perhaps to clearing of preexisting cracks and creation of new cracks, to depths of several kilometers. This may cause mixing of groundwater from previously isolated reservoirs and impact the safety of groundwater supplies and underground waste repositories. The method demonstrated here may hold promise for monitoring aquitard breaching by both natural and anthropogenic processes.
Spatially coherent trends of annual maximum daily precipitation in the United States
Authors: Sun Xun , Lall Upmanu
Published: November 2015

A new multilevel, hierarchical Bayesian model is developed to simultaneously identify clusters of stations with similar temporal patterns, the trend associated with each cluster and for the individual stations within each cluster. An application to the annual maximum daily precipitation in the United States for a common 70 year (1941–2010) period across the HADEX2 sites is presented. The model identifies statistically homogeneous regions, spatially clustering the data into groups according to the intensity and the trend. Partial pooling of model parameters for each group is considered. Spatially consistent trends are detected in the Midwest and Northeast U.S., at the cluster and at the station level. The new approach can dramatically improve trend identification for precipitation extremes; e.g., all 14 stations in the Midwest report a significant trend as opposed to only 4 stations based on single site analysis. The method is generally applicable for improving trend identification over a heterogeneous region.
Ozone‐induced climate change propped up by the Southern Hemisphere oceanic front
Authors: Ogawa Fumiaki , Omrani Nour‐Eddine , Nishii Kazuaki , Nakamura Hisashi , Keenlyside Noel
Published: November 2015

The late twentieth century was marked by a significant summertime trend in the Southern Annular Mode (SAM), the dominant mode of tropospheric variability in the extratropical Southern Hemisphere (SH). This trend with poleward shifting tropospheric westerlies was attributed to downward propagation of stratospheric changes induced by ozone depletion. However, the role of the ocean in setting the SAM response to ozone depletion and its dynamical forcing remains unclear. Here we show, using idealized experiments with a state‐of‐the‐art atmospheric model and analysis of Intergovernmental Panel on Climate Change climate simulations, that frontal sea surface temperature gradients in the midlatitude SH are critical for translating the ozone‐induced stratospheric changes down to the surface. This happens through excitation of wave forcing, which controls the vertical connection of the tropospheric SAM with the stratosphere and shows the importance of internal tropospheric dynamics for stratosphere/troposphere coupling. Thus, improved simulation of oceanic fronts may reduce uncertainties in simulating SH ozone‐induced climate changes.
A submonthly database for detecting changes in vegetation‐atmosphere coupling
Authors: Zscheischler Jakob , Orth René , Seneviratne Sonia I.
Published: November 2015

Land‐atmosphere coupling and changes in coupling regimes are important for making precise future climate predictions and understanding vegetation‐climate feedbacks. Here we introduce the Vegetation‐Atmosphere Coupling (VAC) index which identifies regions and times of concurrent strong anomalies in temperature and photosynthetic activity. The different classes of the index determine whether a location is currently in an energy‐limited or water‐limited regime, and its high temporal resolution allows to investigate how these regimes change over time at the regional scale. We show that the VAC index helps to distinguish different evaporative regimes. It can therefore provide indirect information about the local soil moisture state. We further demonstrate how the index can be used to understand processes leading to and occurring during extreme climate events, using the 2010 heat wave in Russia and the 2010 Amazon drought as examples.
A coupled ionosphere‐raytrace model for high‐power HF heating
Authors: Zawdie K. A. , Huba J. D. , Drob D. P. , Bernhardt P. A.
Published: November 2015

The first 3‐D model of artificial HF ionospheric heating to self‐consistently calculate the modification in heating location due to evolving ionospheric gradients has been developed. The model combines the ionosphere model SAMI3/ESF and the HF propagation code MoJo‐15. At each time step, the simulated path of the HF wave through the ionosphere is used to determine the HF heating location. These calculations have been used to explain the physical mechanism responsible for the snapback effect observed in an Arecibo HF heating experiment described by Bernhardt et al. (1988). The heater wave is refracted by the density cavity, which causes the heating location to drift in longitude. Eventually, the density cavity convects into the path of the refracted ray, such that only a small portion of the ray is above the threshold for HF heating and the heating location snaps back even though the ray itself is still refracted in longitude.
High‐resolution wind speed measurements using actively heated fiber optics
Authors: Sayde Chadi , Thomas Christoph K. , Wagner James , Selker John
Published: November 2015

We present a novel technique to simultaneously measure wind speed (U) at thousands of locations continuously in time based on measurement of velocity‐dependent heat transfer from a heated surface. Measuring temperature differences between paired passive and actively heated fiber‐optic (AHFO) cables with a distributed temperature sensing system allowed estimation ofUat over 2000 sections along the 230 m transect (resolution of 0.375 m and 5.5 s). The underlying concept is similar to that of a hot wire anemometer extended in space. The correlation coefficient betweenUmeasured by two colocated sonic anemometers and the AHFO were 0.91 during the day and 0.87 at night. The combination of classical passive and novel AHFO provides unprecedented dynamic observations of both air temperature and wind speed spanning 4 orders of magnitude in spatial scale (0.1–1000 m) while resolving individual turbulent motions, opening new opportunities for testing basic theories for near‐surface geophysical flows.
Simultaneous ground‐based optical and HF radar observations of the ionospheric footprint of the open/closed field line boundary along the geomagnetic meridian
Authors: Chen X.‐C. , Lorentzen D. A. , Moen J. I. , Oksavik K. , Baddeley L. J.
Published: November 2015

Previous studies have confirmed that the equatorward boundaries of OI 630.0 nm auroral emissions and broad Doppler spectral widths in Super Dual Auroral Radar Network (SuperDARN) data, the so‐called spectral width boundary (SWB), are good empirical proxies for the dayside open/closed field line boundary (OCB) in the ionosphere. However, both observational techniques are associated with mapping errors. SuperDARN uses a virtual height model for mapping, but it is not well known how the mapping error responds to a changing background ionosphere or transient reconnection events. Optical instruments, such as the meridian‐scanning photometers, have high spatial resolution near zenith, where the mapping error due to the assumed OI 630.0 nm auroral emission height becomes small by comparison. In this work, an adjusted method is introduced to identify the SWB, which does not require temporal smoothing across several scans. The difference in latitude between the SWB, as identified using this method, and the simultaneously observed OI 630.0 nm auroral emission boundary along a common line of sight is compared. Utilizing the OI 630.0 nm boundary as a reference location, we present two case studies observed at different levels of solar activity. In both instances the latitude offset of SWB from the reference location is discussed in relation to the background ionospheric electron density. The compared results indicate that the intake of high‐density solar extreme ultraviolet ionized plasma from subauroral latitudes causes a refraction of the HF radar beam path, which results in an overestimation of range mapping. The adjusted method would thus be a useful tool for identifying the OCB under changing ionospheric conditions in the cusp region.
Low‐latitude ionosphere response to super geomagnetic storm of 17/18 March 2015: Results from a chain of ground‐based observations over Indian sector
Authors:   Ramsingh, Sripathi S. , Sreekumar Sreeba , Banola S. , Emperumal K. , Tiwari P. , Kumar Burudu Suneel
Published: November 2015

In this paper, we present unique results of equatorial and low‐latitude ionosphere response to one of the major geomagnetic storms of the current solar cycle that occurred during 17–18 March 2015, where Dst reached its minimum of −228 nT. Here we utilized data from magnetometers, chain of ionosondes located at Tirunelveli (8.73°N, 77.70°E; geometry: 0.32°N), Hyderabad (17.36°N, 78.47°E; geometry 8.76°N), and Allahabad (25.45°N, 81.85°E; geometry 16.5°N) along with multistation GPS receivers over Indian sector. The observations showed a remarkable increase of h′F to as high as ~560 km over Tirunelveli (magnetic equator) with vertical drift of ~70 m/s at 13:30 UT due to direct penetration of storm time eastward electric fields which exactly coincided with the local time of pre‐reversal enhancement (PRE) and caused intense equatorial spread F irregularities in ionosondes and scintillations in GPS receivers at wide latitudes. Plasma irregularities are so intense that their signatures are seen in Allahabad/Lucknow. Storm time thermospheric meridional winds as estimated using two ionosondes suggest the equatorward surge of gravity waves with period of ~2 h. Suppression of anomaly crest on the subsequent day of the storm suggests the complex role of disturbance dynamo electric fields and disturbance wind effects. Our results also show an interesting feature of traveling ionospheric disturbances possibly associated with disturbance meridional wind surge during recovery phase. In addition, noteworthy observations are nighttime westward zonal drifts and PRE‐related total electron content enhancements at anomaly crests during main phase and counter electrojet signatures during recovery phase.
Sustained lobe reconnection in Saturn's magnetotail
Authors: Thomsen M. F. , Jackman C. M. , Mitchell D. G. , Hospodarsky G. , Kurth W. S. , Hansen K. C.
Published: November 2015

The degree to which solar wind driving may affect Saturn's magnetosphere is not yet fully understood. We present observations that suggest that under some conditions the solar wind does govern the character of the plasma sheet in Saturn's outer magnetosphere. On 16 September 2006, the Cassini spacecraft, at a radial distance of 37 Rs near local midnight, observed a sunward flowing ion population for ~5 h, which was accompanied by enhanced Saturn Kilometric Radiation emissions. We interpret this beam as the outflow from a long‐lasting episode of Dungey‐type reconnection, i.e., reconnection of previously open flux containing magnetosheath material. The beam occurred in the middle of a several‐day interval of SKR activity and enhanced lobe magnetic field strength, apparently caused by the arrival of a solar wind compression region with significantly higher than average dynamic pressure. The arrival of the high‐pressure solar wind also marked a change in the composition of the plasma‐sheet plasma, from water‐group‐dominated material clearly of inner‐magnetosphere origin to material dominated by light‐ion composition, consistent with captured magnetosheath plasma. This event suggests that under the influence of prolonged high solar wind dynamic pressure, the tail plasma sheet, which normally consists of inner‐magnetospheric plasma, is eroded away by ongoing reconnection that then involves open lobe field lines. This process removes open magnetic flux from the lobes and creates a more Earth‐like, Dungey‐style outer plasma sheet dominantly of solar wind origin. This behavior is potentially a recurrent phenomenon driven by repeating high‐pressure streams (corotating interaction regions) in the solar wind, which also drive geomagnetic storms at Earth.
Effects of Earth's rotation on the early differentiation of a terrestrial magma ocean
Authors: Maas Christian , Hansen Ulrich
Published: November 2015

Similar to other terrestrial planets like Moon and Mars, Earth experienced a magma ocean period about 4.5 billion years ago. On Earth differentiation processes in the magma ocean set the initial conditions for core formation and mantle evolution. During the magma ocean period Earth was rotating significantly faster than today. Further, the viscosity of the magma was low, thus that planetary rotation potentially played an important role for differentiation. However, nearly all previous studies neglect rotational effects. All in all, our results suggest that planetary rotation plays an important role for magma ocean crystallization. We employ a 3‐D numerical model to study crystal settling in a rotating and vigorously convecting early magma ocean. We show that crystal settling in a terrestrial magma ocean is crucially affected by latitude as well as by rotational strength and crystal density. Due to rotation an inhomogeneous accumulation of crystals during magma ocean solidification with a distinct crystal settling between pole and equator could occur. One could speculate that this may have potentially strong effects on the magma ocean solidification time and the early mantle composition. It could support the development of a basal magma ocean and the formation of anomalies at the core‐mantle boundary in the equatorial region, reaching back to the time of magma ocean solidification.
Near‐inertial ocean response to tropical cyclone forcing on the Australian North‐West Shelf
Authors: Rayson M. D. , Ivey G. N. , Jones N. L. , Lowe R. J. , Wake G. W. , McConochie J. D.
Published: November 2015

The Regional Ocean Modeling System (ROMS) was applied to the Australian North‐West Shelf (NWS) to hindcast the ocean response to four intense historical tropical cyclones (TCs). While the four cyclones had very different trajectories across the NWS, all passed within 150 km of a long‐term vertical mooring located on the continental shelf in 125 m depth. The observed ocean response at this relatively shallow, Southern Hemisphere shelf site was characterized by the development of a peak in the counter‐clockwise (CCW) near‐inertial kinetic energy, mixed layer deepening, and subsequent restratification. Strong near‐inertial isotherm oscillations were also observed following two of the cyclones. ROMS reproduced these features and also showed that the peak in the near‐inertial CCW kinetic energy was observed on the left side of each cyclone trajectory. The time rate of change of near‐inertial kinetic energy depended strongly on the storm Rossby number, i.e., defined based on the storm speed, the storm length scale, and the Coriolis frequency. The shallow water depth on the NWS resulted in first, a more rapid decay of near‐inertial oscillations than in the deep ocean, and second a generation efficiency (the ratio of near‐inertial power to the rate of wind work) of up to 10%, smaller than found for cyclones propagating across deeper water. The total energy put into near‐inertial motions is nevertheless large compared to the background tidal energy. The rapid decay of near‐inertial motions emphasizes the importance of frictional effects in characterizing the response to cyclone forcing in shallow seas.