bluuebunny/crossref_metadata_2025 huggingface dataset:
L’évolution Plio-Quaternaire du bassin du Puy (Massif Central, France) : rythmes morphosédimentaires et volcanisme
Authors: Defive Emmanuelle , Gauthier Agnès , Pastre Jean-François
Published: June 2011

Dans le bassin supérieur de la Loire (Velay, Massif Central, France), l’interaction du volcanisme basaltique Plio-Pléistocène du Devès (3 à 0,8 Ma) et de la dynamique fluviale est à l’origine de nombreuses modifications morphosédimentaires entre 3 et 0,8 Ma. Dans le bassin du Puy, elles ont abouti à la mise en place d’une séquence sédimentaire fluvio-lacustre de 150 m d’épaisseur qui représente un enregistrement de référence pour la connaissance du Pléistocène inférieur européen. Aux marqueurs biostratigraphiques fournis initialement par les faunes de mammifères sont venus s’ajouter d’autres jalons (palynologie, paléomagnétisme, datations K‑Ar, minéraux lourds...) précisant la chronologie du dépôt et le contexte de sa formation. La sédimentation apparaît contrôlée par l’édification en deux temps d’un barrage volcanique à l’exutoire aval du bassin. L’âge de la partie inférieure de ce barrage est fourni par des datations K‑Ar qui permettent de fixer vers 2,5 Ma le début de la sédimentation. Cet âge est corroboré par les données chronostratigraphiques fournies par la séquence lacustre de Ceyssac. Les dépôts accumulés au-dessus des alluvions grossières basales anté-barrage témoignent des ambiances lacustres brutalement induites au sein du bassin par ce premier barrage. Malgré la complexité paléogéographique de la zone, les données sédimentologiques et minéralogiques aident à élaborer un schéma évolutif général. Sphène et apatite du Mont‑Dore sont ainsi indicateurs de cette première étape dans l’élaboration du remblaiement. De même, l’apparition d’augites vertes du Mont-Dore à la partie intermédiaire du dépôt coïncide avec un regain de détritisme au sein du bassin, corrélatif du franchissement du premier barrage. Cet épisode est mal calé chronologiquement. La mise en place vers 2 Ma d’un deuxième barrage superposé au premier provoque le retour rapide d’une sédimentation lacustre qui prend fin vers 1 Ma. Les coulées du plateau du Devès recouvrent alors largement le secteur, avant leur réincision par la Loire et la Borne. Forçant la sédimentation dans le bassin du Puy, le volcanisme y a permis l’enregistrement des modifications bioclimatiques, qui s’expriment de manière générale par des dépôts fins durant les phases tempérées et des apports grossiers durant les périodes froides. Ces données, corroborées par la palynologie des séquences de Ceyssac et de La Rochelambert, établissent en particulier un détritisme accru lors de phases sédimentaires qui semblent se rapporter à l’Éburonien de la chronologie nordique. En amont du bassin du Puy se pose la question d’une corrélation de ces phénomènes sédimentaires avec l’évolution de la morphologie de la vallée, qui passe d’un berceau à une gorge.
Middle and Upper Pleistocene fluvial evolution of the Meurthe and Moselle valleys in the Paris Basin and the Rhenish Massif
Authors: Cordier Stéphane , Frechen Manfred , Harmand Dominique , Beiner Monique
Published: June 2011

The terrace systems of the River Meurthe (Me), and the River Moselle (M) downstream from the present Moselle-Meurthe confluence are composed of eight stepped alluvial terraces (Me8-M8 to Me1-M1), situated at less than 90 m above the modern floodplain Me0-M0. Morphological, mineralogical and petrographical studies evidence that the oldest five terraces (Me8-M8 to Me4-M4) were formed by the “Palaeo-Meurthe”, while the Upper Moselle flowed towards the Meuse valley. Downstream from the confluence, the three youngest alluvial terraces (Me3-M3 to Me1-M1) contain crystalline sediments from the Upper Moselle basin; they have been formed since the Upper Moselle capture, dated about 250-270 ka before present. IRSL and radiocarbon datings provide independent absolute age control for these post-capture terraces, which respectively correlate with the end of the Saalian (Me3-M3) and the Weichselian (Me2-M2 and Me1‑M1). The constant relative height of the terraces between France, Luxemburg and Germany gives evidences that there was no differenciated tectonic movements along the valley since at least the capture. A cyclic evolution scheme for the formation of the terraces is presented. The main gravel sedimentation occurred during cold periods (pleniglacial and late glacial phases), with a minor erosive period at the beginning of late glacial periods. Major incision occurs at the warm-to-cold transition.
Discontinuités dans l'enregistrement des cycles interglaciaire-glaciaire sur un littoral en contexte intraplaque. Exemple du Val de Saire (Normandie, France)
Authors: Coutard Sylvie , Lautridou Jean‑Pierre , Rhodes Edward
Published: June 2011

Les travaux récents menés dans le Val de Saire (Basse-Normandie, France), en bordure d’une mer épicontinentale, la Manche, ont mis en évidence quatre plates-formes d’abrasion marine étagées entre 0 et 35 m d’altitude. Ces plates-formes supportent des dépôts marins siliciclastiques d’épaisseur variable, souvent métrique. Leur étagement témoigne du caractère cyclique de la morphogenèse au Pléistocène moyen due à l’interaction entre variations eustatiques et activité tectonique. L’enregistrement sédimentaire d’une phase interglaciaire, soumis à l’eustatisme, se présente sous la forme d’une séquence marine régressive de type galets-sables. Il n’existe pas de relations stratigraphiques directes entre les dépôts marins des diverses périodes puisque chaque plateforme est séparée de la précédente par une paléofalaise. Lors des phases froides, le Val de Saire a été soumis à l’action d’un climat périglaciaire marqué, avec dégradation des reliefs, mobilisation des versants, apports éoliens… Cette dualité de la morphogenèse au cours des cycles interglaciaireglaciaire est responsable de fortes discontinuités dans l’enregistrement sédimentaire, tant spatiales que temporelles. Les volumes érodés sont importants : les séquences continentales antérieures au dernier cycle ne sont quasiment pas conservées. De plus, la séquence du Pléistocène supérieur, seule préservée, est elle-même incomplète et montre de nombreux hiatus : troncatures majeures pendant et à la fin du stade 5 et au début du stade 4, absence du pédocomplexe du Pléniglaciaire moyen, érosion des loess ante- Nagelbeek. Ainsi, la répétition des processus de formation des plates-formes et du dépôt d’une séquence détritique traduit une continuité dans le fonctionnement d’un système, dans lequel l’enregistrement est intrinsèquement discontinu avec un bilan sédimentaire relativement maigre. Ce système, ici particulièrement bien exprimé, est représentatif d’une grande partie du Massif Armoricain.
Surgical Treatment of Atrial Fibrillation: A Review
Authors: Hiari Nadine
Published: June 2011

Atrial fibrillation is the most commonly sustained arrhythmia in man. While it affects millions of patients worldwide, its incidence will markedly increase with an aging population. Primary goals of AF therapy are to (1) reduce embolic complications, particularly stroke, (2) alleviate symptoms, and (3) prevent long-term heart remodelling. These have been proven to be a challenge as there are major limitations in our knowledge of the pathological and electrophysiological mechanisms underlying AF. Although advances continue to be made in the medical management of this condition, pharmacotherapy is often unsuccessful. Because of the high recurrence rate of AF despite antiarrhythmic drug therapy for maintenance of sinus rhythm and the adverse effects of these drugs, there has been growing interest in nonpharmacological strategies. Surgery for treatment of AF has been around for some time. The Cox-Maze procedure is the gold standard for the surgical treatment of atrial fibrillation and has more than 90% success in eliminating atrial fibrillation. Although the cut and sew maze is very effective, it has been superseded by newer operations that rely on alternate energy sources to create lines of conduction block. In addition, the evolution of improved ablation technology and instrumentation has facilitated the development of minimally invasive approaches. In this paper, the rationale for surgical ablation for atrial fibrillation and the different surgical techniques that were developed will be explored. In addition, it will detail the new approaches to surgical ablation of atrial fibrillation that employ alternate energy sources.
Use of Fine-Needle Aspiration in the Evaluation of Breast Lumps
Authors: Bukhari Mulazim Hussain , Arshad Madiha , Jamal Shahid , Niazi Shahida , Bashir Shahid , Bakhshi Irfan M. , Shaharyar
Published: June 2011

Background. A study was designed to see the role of fine needle aspiration cytology (FNAC) in palpable breast lumps. Materials and Methods. Four hundred and twenty five (425) patients came to the Department of Pathology King Edward Medical University, Lahore in four years for FNAC of their palpable breast masses from June 2006 to June 2010. FNAC diagnosis was compared with histological diagnosis to see the accuracy of fine needle aspiration cytology for neoplastic lesions. Results. There were 271/425 benign, 120/425 malignant, and 32/425 suspicious smears. Inadequate samples were repeated twice or thrice, and the degree of success was improved with consecutive repeating approaches. The frequency of inadequacy declined from 86 to 18, and 2 for first, second and third attempts, respectively. The number of repeats increased the diagnostic accuracy of aspirates which is statistically significant (). Invasive ductal carcinoma was the most commonly reported lesion with maximum incidence in the 4th, 5th, and 6th decades followed by invasive lobular carcinoma and other malignant lesions. The sensitivity, specificity, accuracy, negative predictive value, and the positive predictive value of FNAC was 98%, 100%, 98%, 100%, and 97%, respectively.
Conclusion. FNAC serves as a rapid, economical, and reliable tool for the diagnosis of palpable breast lesions because the cytopathological examination of these lesions before operation or treatment serves as an important diagnostic modality.
Clinical Impact of Hypercalcemia in Kidney Transplant
Authors: Messa Piergiorgio , Cafforio Cosimo , Alfieri Carlo
Published: June 2011

Hypercalcemia (HC) has been variably reported in kidney transplanted (KTx) recipients (5–15%). Calcium levels peak around the 3rd month after KTx and thereafter slightly reduce and stabilize. Though many factors have been claimed to induce HC after KTx, the persistence of posttransplant hyperparathyroidism (PT-HPT) of moderate-severe degree is universally considered the first causal factor. Though not proven, there are experimental and clinical suggestions that HC can adversely affect either the graft (nephrocalcinosis) and other organs or systems (vascular calcifications, erythrocytosis, pancreatitis, etc.). However, there is no conclusive evidence that correction of serum calcium levels might avoid the occurrence of these claimed clinical effects of HC. The best way to reduce the occurrence of HC after KTx is to treat as best we can the secondary hyperparathyroidism (SHP) during the uraemic stages. The indication to Parathyroidectomy (PTX), either before or after KTx, in order to prevent or to treat, respectively, HC after KTx, is still a matter of debate which has been revived by the availability of the calcimimetic cinacalcet for the treatment of PT-HPT. However, we still need to better clarify many points as regards the potential adverse effects related to either PTX or cinacalcet use in this clinical set, and we are waiting for the results of future randomized controlled trials to achieve some more definite conclusions on this topic.
A Case Report of a Patient with Ribbing Disease Underlines the Connections between the Skeletal and Cardiovascular Complications
Authors: Cocco Giuseppe , Gasparyan Armen Yuri
Published: June 2011

A 69-year-old woman suffered from Ribbing disease, a hereditary X autosomal dominant disease with multiple sclerosing dysplasias. However, it is less known that the genetic mutation can often induce cardiovascular complications. The patient had a hypertensive cardiopathy and had been treated with percutaneous coronary angioplasty and stenting because of a myocardial infarction. She was seen because of dyspnea and we detected an aneurysm of the ascending thoracic aorta. The patient underwent surgical repair. In Ribbing disease an up-regulation of genes interferes with the production, processing, or formation of collagen type II and XI. These genetic effects are thought to be specific for osteoblasts and are responsible for the skeletal pathology. However, the defective synthesis of collagen can also induce cardiovascular complications which may be similar to those described in patients with type III Ehlers-Danlos syndrome, with type IV Marfan syndrome, and with osteogenesis imperfecta. Rheumatologists who treat patients with Ribbing disease should seek the advice of cardiologists for the occurrence of cardiovascular complications.
Elevated Alkaline Phosphatase in Children: An Algorithm to Determine When a “Wait and See” Approach is Optimal
Authors: Otero Jaclyn L. , González-Peralta Regino P. , Andres Joel M. , Jolley Christopher D. , Novak Don A. , Haafiz Allah
Published: June 2011

Due to the possibility of underlying hepatobiliaryor bone diseases, the diagnostic work up of a child with elevated alkaline phosphatase (AP) levels can be quite costly. In a significant proportion of these patients, elevated AP is benign, requiring no intervention: hence, known as transient hyperphosphatasemia (THP) of infants and children. A 27-month old previously healthy Caucasian female was found to have isolated elevation of AP four weeks after the initial symptoms of acute gastroenteritis. One month later, when seen in hepatobiliary clinic, signs and symptoms of gastrointestinal, hepatobiliary, or bone disease were absent and physical examination was normal. The diagnosis of THP was made, and, as anticipated, AP levels normalized after four months. Using this case as an example, we suggest an algorithm that can be utilized as a guide in a primary care setting to arrive at the diagnosis of THP and avoid further tests or referrals.
A note on hybrid heteroclinic solutions for a class of semilinear elliptic PDEs
Authors: Bolotin Sergey , Rabinowitz Paul H.
Published: June 2011

Variational methods will be used to find solutions of a semilinear elliptic PDE by ‘‘glueing’’ mountain pass critical points of the corresponding functional to minima or to other mountain pass critical points.
Some recent results concerning a class of forward-backward parabolic equations
Authors: Smarrazzo Flavia , Tesei Alberto
Published: June 2011

We study a quasilinear parabolic equation of forward-backward type in one space dimension, under assumptions on the nonlinearity satisfied by important mathematical models (e.g., the one-dimensional Perona–Malik equation). We first address a degenerate pseudoparabolic regularization of the equation, which takes time delay e¤ects into account, proving existence and uniqueness of positive solutions of the regularized problem in a space of Radon measures, as well as qualitative properties of such solutions. Then we address the vanishing viscosity limit of the regularized problem, proving that the limiting points (in a suitable topology) of the family of solutions of the regularized problem can be regarded as solutions of the original problem. In particular, we characterize the disintegration of the narrow limit of the family of Young measures associated with the absolutely continuous part of the solutions of the regularized problem, proving that it is a superposition of two Dirac masses with support on the branches of the graph of the nonlinearity
φ
. In the above study, the existence of a family of infinitely many entropy inequalities plays an important role.
Transition of Liesegang Precipitation Systems: Simulations with an Adaptive Grid PDE Method
Authors: Zegeling Paul A. , Lagzi István , Izsák Ferenc
Published: June 2011

The dynamics of the Liesegang type pattern formation is investigated in a centrally symmetric two-dimensional setup. According to the observations in real experiments, the qualitative change of the dynamics is exhibited for slightly different initial conditions. Two kinds of chemical mechanisms are studied; in both cases the pattern formation is described using a phase separation model including the Cahn-Hilliard equations. For the numerical simulations we make use of an adaptive grid PDE method, which successfully deals with the computationally critical cases such as steep gradients in the concentration distribution and investigation of long time behavior. The numerical simulations show a good agreement with the real experiments.
A Kinetic Monte Carlo Approach for Self-Diffusion of Pt Atom Clusters on a Pt(111) Surface
Authors: Deák R. , Néda Z. , Barna P. B.
Published: June 2011

A lattice Kinetic Monte Carlo (KMC) approach is considered to study the statistical properties of the diffusion of Pt atom clusters on a Pt(111) surface. The interatomic potential experienced by the diffusing atoms is calculated by the embedded atom method and the hopping barrier for the allowed atomic movements are calculated using the Nudged Elastic Band method. The diffusion coefficient is computed for various cluster sizes and system temperatures. The obtained results are in agreement with the ones obtained in previous experimental and theoretical works. A simple scaling argument is proposed for the size dependence of the diffusion coefficient’s pre-factor. A detailed statistical analysis of the event by event KMC dynamics reveals two important and co-existing mechanisms for the diffusion of the cluster’s center of mass. At low temperatures (below T = 400K) the dominating mechanism responsible for the displacement of the cluster’s center of mass is the periphery (or edge) diffusion of the atoms. At high temperatures (above T = 800K) the dissociation and recombination of the clusters becomes more and more important.
Conservative Semi-Lagrangian Finite Difference WENO Formulations with Applications to the Vlasov Equation
Authors: Qiu Jing-Mei , Shu Chi-Wang
Published: June 2011

In this paper, we propose a new conservative semi-Lagrangian (SL) finite difference (FD) WENO scheme for linear advection equations, which can serve as a base scheme for the Vlasov equation by Strang splitting [4]. The reconstruction procedure in the proposed SL FD scheme is the same as the one used in the SL finite volume (FV) WENO scheme [3]. However, instead of inputting cell averages and approximate the integral form of the equation in a FV scheme, we input point values and approximate the differential form of equation in a FD spirit, yet retaining very high order (fifth order in our experiment) spatial accuracy. The advantage of using point values, rather than cell averages, is to avoid the second order spatial error, due to the shearing in velocity (v) and electrical field (E) over a cell when performing the Strang splitting to the Vlasov equation. As a result, the proposed scheme has very high spatial accuracy, compared with second order spatial accuracy for Strang split SL FV scheme for solving the Vlasov-Poisson (VP) system. We perform numerical experiments on linear advection, rigid body rotation problem; and on the Landau damping and two-stream instabilities by solving the VP system. For comparison, we also apply (1) the conservative SL FD WENO scheme, proposed in [22] for incompressible advection problem, (2) the conservative SL FD WENO scheme proposed in [21] and (3) the non-conservative version of the SL FD WENO scheme in [3] to the same test problems. The performances of different schemes are compared by the error table, solution resolution of sharp interface, and by tracking the conservation of physical norms, energies and entropies, which should be physically preserved.
Particle Collisions in a Lumped Particle Model
Authors: al-Khayat Omar , Bruaset Are Magnus , Langtangen Hans Petter
Published: June 2011

This paper presents an extension of the lumped particle model in [1] to include the effects of particle collisions. The lumped particle model is a flexible framework for the modeling of particle laden flows, that takes into account fundamental features, including advection, diffusion and dispersion of the particles. In this paper, we transform a binary collision model and concepts from kinetic theory into a collision procedure for the lumped particle framework. We apply this new collision procedure to investigate numerically the role of particle collisions in the hindered settling effect. The hindered settling effect is characterized by an increase in the effective drag coefficient CD that influences each particle in the flow. This coefficient is given by , where ϕ is the volume fraction of particles, is the drag coefficient for a single particle, and n ≃ 4.67 for creeping flow. We obtain an approximation for CD/CD by calculating the effective work done by collisions, and comparing that to the work done by the drag force. In our numerical experiments, we observe a minimal value of n = 3.0. Moreover, by allowing high energy dissipation, an approximation for the classical value for creeping flow, n = 4.7, is reproduced. We also obtain high values for n, up to n = 6.5, which is consistent with recent physical experiments on the sedimentation of sand grains.
Development and Validation of Detailed Clinical Models for Nursing Problems in Perinatal care
Authors: Kim Y. , Park H.-A.
Published: June 2011

Objectives: The aims of this study were to develop detailed clinical models (DCMs) for nursing problems related to perinatal care and to test the applicability of these detailed clinical models. Methods: First, we extracted entities of nursing problems by analyzing nursing-problem statements from nursing records, reviewing the literature, and interviewing nurse experts. Second, we extracted attributes and possible values needed to describe the entities in more detail by again analyzing nursing statements, reviewing the literature, and consulting nurse experts. Third, DCMs were modeled by linking each entity with possible attributes with value sets and optionalities. Fourth, entities, attributes and value sets in the DCMs were mapped to the International Classification for Nursing Practice (ICNP) version 2. Finally, DCMs were validated by consulting a group of experts and by applying them to real clinical data and nursing care scenarios published in the literature. The adequacy of the entities, attributes, value sets, and optionalities of the attributes were validated.

Results: Fifty-eight entities were identified, 41 entities from nursing records, 12 entities from literature review and 5 entities from nurse experts. Sixty-five attributes with values were identified, 25 attributes from nursing records, 34 attributes from literature review, and 6 attributes from nurse experts. In total 58 DCMs were developed and validated.

Conclusions: The DCMs developed in this study can ensure that electronic health records contain meaningful and valid information, and support the semantic interoperability of nursing information.
Evaluation of cloud convection and tracer transport in a three-dimensional chemical transport model
Authors: Feng W. , Chipperfield M. P. , Dhomse S. , Monge-Sanz B. M. , Yang X. , Zhang K. , Ramonet M.
Published: June 2011

Abstract. We investigate the performance of cloud convection and tracer transport in a global off-line 3-D chemical transport model. Various model simulations are performed using different meteorological (re)analyses (ERA-40, ECMWF operational and ECMWF Interim) to diagnose the updraft mass flux, convective precipitation and cloud top height. The diagnosed upward mass flux distribution from TOMCAT agrees quite well with the ECMWF reanalysis data (ERA-40 and ERA-Interim) below 200 hPa. Inclusion of midlevel convection improves the agreement at mid-high latitudes. However, the reanalyses show strong convective transport up to 100 hPa, well into the tropical tropopause layer (TTL), which is not captured by TOMCAT. Similarly, the model captures the spatial and seasonal variation of convective cloud top height although the mean modelled value is about 2 km lower than observed. The ERA-Interim reanalyses have smaller archived upward convective mass fluxes than ERA-40, and smaller convective precipitation, which is in better agreement with satellite-based data. TOMCAT captures these relative differences when diagnosing convection from the large-scale fields. The model also shows differences in diagnosed convection with the version of the operational analyses used, which cautions against using results of the model from one specific time period as a general evaluation. We have tested the effect of resolution on the diagnosed modelled convection with simulations ranging from 5.6° × 5.6° to 1° × 1°. Overall, in the off-line model, the higher model resolution gives stronger vertical tracer transport, however, it does not make a large change to the diagnosed convective updraft mass flux (i.e., the model results using the convection scheme fail to capture the strong convection transport up to 100 hPa as seen in the archived convective mass fluxes). Similarly, the resolution of the forcing winds in the higher resolution CTM does not make a large improvement compared to the archived mass fluxes. Including a radon tracer in the model confirms the importance of convection for reproducing observed midlatitude profiles. The model run using archived mass fluxes transports significantly more radon to the upper troposphere but the available data does not strongly discriminate between the different model versions.
Characterization of wildfire NOx emissions using MODIS fire radiative power and OMI tropospheric NO2 columns
Authors: Mebust A. K. , Russell A. R. , Hudman R. C. , Valin L. C. , Cohen R. C.
Published: June 2011

Abstract. We use observations of fire radiative power (FRP) from the Moderate Resolution Imaging Spectroradiometer~(MODIS) and tropospheric NO2 column measurements from the Ozone Monitoring Instrument (OMI) to derive NO2 wildfire emission coefficients (g MJ−1) for three land types over California and Nevada. Retrieved emission coefficients were 0.279±0.077, 0.342±0.053, and 0.696±0.088 g MJ−1 NO2 for forest, grass and shrub fuels, respectively. These emission coefficients reproduce ratios of emissions with fuel type reported previously using independent methods. However, the magnitude of these coefficients is lower than prior estimates. While it is possible that a negative bias in the OMI NO2 retrieval over regions of active fire emissions is partly responsible, comparison with several other studies of fire emissions using satellite platforms indicates that current emission factors may overestimate the contributions of flaming combustion and underestimate the contributions of smoldering combustion to total fire emissions. Our results indicate that satellite data can provide an extensive characterization of the variability in fire NOx emissions; 67 % of the variability in emissions in this region can be accounted for using an FRP-based parameterization.
Thin and subvisible cirrus and contrails in a subsaturated environment
Authors: Kübbeler M. , Hildebrandt M. , Meyer J. , Schiller C. , Hamburger Th. , Jurkat T. , Minikin A. , Petzold A. , Rautenhaus M. , Schlager H. , Schumann U. , Voigt C. , Spichtinger P. , Gayet J.-F. , Gourbeyre C. , Krämer M.
Published: June 2011

Abstract. The frequency of occurrence of cirrus clouds and contrails, their life time, ice crystal size spectra and thus their radiative properties depend strongly on the ambient distribution of the relative humidity with respect to ice (RHice). Ice clouds do not form below a certain supersaturation and both cirrus and contrails need at least saturation conditions to persist over a longer period. Under subsaturated conditions, cirrus and contrails should dissipate. During the mid-latitude aircraft experiment CONCERT 2008 (CONtrail and Cirrus ExpeRimenT), RHice and ice crystals were measured in cirrus and contrails. Here, we present results from 2.3/1.7 h of observation in cirrus/contrails during 6 flights. Thin and subvisible cirrus with contrails embedded therein have been detected frequently in a subsaturated environment. Nevertheless, ice crystals up to radii of 50 μm and larger, but with low number densities were often observed inside the contrails as well as in the cirrus. Analysis of the meteorological situation indicates that the crystals in the contrails were entrained from the thin/subvisible cirrus clouds, which emerged in frontal systems with low updrafts. From model simulations of cirrus evaporation times it follows that such thin/subvisible cirrus can exist for time periods of a couple of hours and longer in a subsaturated environment and thus may represent a considerable part of the cirrus coverage.
Development and evaluation of the aerosol dynamics and gas phase chemistry model ADCHEM
Authors: Roldin P. , Swietlicki E. , Schurgers G. , Arneth A. , Lehtinen K. E. J. , Boy M. , Kulmala M.
Published: June 2011

Abstract. The aim of this work was to develop a model suited for detailed studies of aerosol dynamics, gas and particle phase chemistry within urban plumes, from local scale (1 × 1 km2) to regional scale. This article describes and evaluates the trajectory model for Aerosol Dynamics, gas and particle phase CHEMistry and radiative transfer (ADCHEM). The model treats both vertical and horizontal dispersion perpendicular to an air mass trajectory (2-space dimensions). The Lagrangian approach enables a more detailed representation of the aerosol dynamics, gas and particle phase chemistry and a finer spatial and temporal resolution compared to that of available regional 3D-CTMs. These features make it among others well suited for urban plume studies. The aerosol dynamics model includes Brownian coagulation, dry deposition, wet deposition, in-cloud processing, condensation, evaporation, primary particle emissions and homogeneous nucleation. The organic mass partitioning was either modeled with a 2-dimensional volatility basis set (2D-VBS) or with the traditional two-product model approach. In ADCHEM these models consider the diffusion limited and particle size dependent condensation and evaporation of 110 and 40 different organic compounds respectively. The gas phase chemistry model calculates the gas phase concentrations of 61 different species, using 130 different chemical reactions. Daily isoprene and monoterpene emissions from European forests were simulated separately with the vegetation model LPJ-GUESS, and included as input to ADCHEM. ADCHEM was used to simulate the ageing of the urban plumes from the city of Malmö in southern Sweden (280 000 inhabitants). Several sensitivity tests were performed concerning the number of size bins, size structure method, aerosol dynamic processes, vertical and horizontal mixing, coupled or uncoupled condensation and the secondary organic aerosol formation. The simulations show that the full-stationary size structure gives accurate results with little numerical diffusion when more than 50 size bins are used between 1.5 and 2500 nm, while the moving-center method is preferable when only a few size bins are selected. The particle number size distribution in the center of the urban plume from Malmö was mainly affected by dry deposition, coagulation and vertical dilution. The modeled PM2.5 mass was dominated by organic material, nitrate, sulfate and ammonium. If the condensation of HNO3 and NH3 was treated as a coupled process (pH independent) the model gave lower nitrate PM2.5 mass than if considering uncoupled condensation. Although the time of ageing from that SOA precursors are emitted until condensable products are formed is substantially different with the 2D-VBS and two product model, the models gave similar total organic mass concentrations.
Aerosol ageing in an urban plume – implication for climate
Authors: Roldin P. , Swietlicki E. , Massling A. , Kristensson A. , Löndahl J. , Eriksson A. , Pagels J. , Gustafsson S.
Published: June 2011

Abstract. The climate effects downwind of an urban area resulting from gaseous and particulate emissions within the city are as yet inadequately quantified. The aim of this work was to estimate these effects for Malmö city in southern Sweden (population 280 000). The chemical and physical particle properties were simulated with a model for Aerosol Dynamics, gas phase CHEMistry and radiative transfer calculations (ADCHEM) following the trajectory movement from upwind of Malmö, through the urban background environment and finally tens and hundreds of kilometers downwind of Malmö. The model results were evaluated using measurements of the particle number size distribution and chemical composition. The total particle number concentration 50 km (~ 3 h) downwind, in the center of the Malmö plume, is about 3700 cm−3 of which the Malmö contribution is roughly 30%. Condensation of nitric acid, ammonium and to a smaller extent oxidized organic compounds formed from the emissions in Malmö increases the secondary aerosol formation with a maximum of 0.7–0.8 μg m−3 6 to 18 h downwind of Malmö. The secondary mass contribution dominates over the primary soot contribution from Malmö already 3 to 4 h downwind of the emission sources and contributes to an enhanced total surface direct or indirect aerosol shortwave radiative forcing in the center of the urban plume ranging from −0.3 to −3.3 W m−2 depending on the distance from Malmö, and the specific cloud properties.
Wind tunnel experiments on the retention of trace gases during riming: nitric acid, hydrochloric acid, and hydrogen peroxide
Authors: von Blohn N. , Diehl K. , Mitra S. K. , Borrmann S.
Published: June 2011

Abstract. Laboratory experiments were carried out in a vertical wind tunnel to study the retention of different atmospheric trace gases during riming. In the experiments, the rimed ice particles floated in a laminar air stream carrying a cloud of supercooled droplets with radii between 10 and 20 μm. Ice particles, dendritic ice crystals, and snow flakes with diameters between 6 mm and 1.5 cm were allowed to rime at temperatures between −5 and −12 °C where riming mainly proceeds in the atmosphere and with cloud liquid water contents between 1 and 1.5 g m−3 which are values typically found in atmospheric mixed phase clouds. Three trace species were investigated, nitric and hydrochloric acid, and hydrogen peroxide. They were present in the supercooled liquid droplets in concentrations from 1 to 120 ppmv, i.e. similar to the ones measured in cloud drops. The chemical analyses of the rimed ice particles allow to determine the trace species concentration in the ice phase. Together with the known liquid phase concentration the retention coefficients were calculated in terms of the amount of the species which remained in the ice phase after freezing. It was found that the highly soluble trace gases nitric and hydrochloric acid were retained nearly completely (98.6 ± 8 % and 99.7 ± 9 %, respectively) while for hydrogen peroxide a retention coefficient of 64.3 ± 11 % was determined. No influence of the riming temperature on the retention was found which can be explained by the fact that in the observed range of temperature and liquid water content riming proceeded in the dry growth regime.
Sources and seasonality of atmospheric methanol based on tall tower measurements in the US Upper Midwest
Authors: Hu L. , Mohr M. J. , Wells K. C. , Griffis T. J. , Helmig D. , Millet D. B.
Published: June 2011

Abstract. We present over one year of continuous atmospheric methanol measurements from the University of Minnesota tall tower Trace Gas Observatory (KCMP tall tower; 244 m a.g.l.), and interpret the dataset in terms of constraints on regional methanol sources and seasonality. The seasonal cycle of methanol concentrations observed at the KCMP tall tower is generally similar to that simulated by a global 3-D chemical transport model (GEOS-Chem, driven with MEGANv2.0 biogenic emissions) except the seasonal peak occurs ~1 month earlier in the observations, apparently reflecting a model underestimate of emission rates for younger versus older leaves. Based on a source tracer approach, which we evaluate using GEOS-Chem and with multiple tracers, we estimate that anthropogenic emissions account for approximately 40 % of ambient methanol abundance during winter and 10 % during summer. During daytime in summer, methanol concentrations increase exponentially with temperature, reflecting the temperature sensitivity of the biogenic source, and the observed temperature dependence is statistically consistent with that in the model. Nevertheless, summertime concentrations are underestimated by on average 35 % in the model for this region. The seasonal importance of methanol as a source of formaldehyde (HCHO) and carbon monoxide (CO) is highest in spring through early summer, when biogenic methanol emissions are high but isoprene emissions are still relatively low. During that time observed methanol concentrations account for on average 20 % of the total CO and HCHO production rates as simulated by GEOS-Chem, compared to 12 % later in the summer and 12 % on an annual average basis. The biased seasonality in the model means that the photochemical role for methanol early in the growing season is presently underestimated.
Flight-based chemical characterization of biomass burning aerosols within two prescribed burn smoke plumes
Authors: Pratt K. A. , Murphy S. M. , Subramanian R. , DeMott P. J. , Kok G. L. , Campos T. , Rogers D. C. , Prenni A. J. , Heymsfield A. J. , Seinfeld J. H. , Prather K. A.
Published: June 2011

Abstract. Biomass burning represents a major global source of aerosols impacting direct radiative forcing and cloud properties. Thus, the goal of a number of current studies involves developing a better understanding of how the chemical composition and mixing state of biomass burning aerosols evolve during atmospheric aging processes. During the Ice in Cloud Experiment – Layer Clouds (ICE-L) in fall of 2007, smoke plumes from two small Wyoming Bureau of Land Management prescribed burns were measured by on-line aerosol instrumentation aboard a C-130 aircraft, providing a detailed chemical characterization of the particles. After ~2–4 min of aging, submicron smoke particles, produced primarily from sagebrush combustion, consisted predominantly of organics by mass, but were comprised primarily of internal mixtures of organic carbon, elemental carbon, potassium chloride, and potassium sulfate. Significantly, 100 % of the fresh biomass burning particles contained minor mass fractions of nitrate and sulfate, suggesting that hygroscopic material is incorporated very near or at the point of emission. The mass fractions of ammonium, sulfate, and nitrate increased with aging up to ~81–88 min and resulted in acidic particles, with both nitric acid and sulfuric acid present. Decreasing black carbon mass concentrations occurred due to dilution of the plume. Increases in the fraction of oxygenated organic carbon and the presence of dicarboxylic acids, in particular, were observed with aging. Cloud condensation nuclei measurements suggested all particles >100 nm were active at 0.5 % water supersaturation in the smoke plumes, confirming the relatively high hygroscopicity of the freshly emitted particles. For immersion/condensation freezing, ice nuclei measurements at −32 °C suggested activation of ~0.03–0.07 % of the particles with diameters greater than 500 nm.
Interannual variability of ozone and carbon monoxide at the Whistler high elevation site: 2002–2006
Authors: Macdonald A. M. , Anlauf K. G. , Leaitch W. R. , Chan E.
Published: June 2011

Abstract. In spring 2002, an atmospheric measurement site was established at the peak of Whistler Mountain in British Columbia, Canada to measure trace gases, particle chemistry and physics, and meteorology. This paper uses continuous measurements from March 2002 to December 2006 to investigate the influence of trans-Pacific transport and North American forest fires on both O3 and CO at Whistler. Annual mean mixing ratios of O3 and CO were 41 ppbv (monthly means of 35–48 ppbv) and 145 ppbv (monthly means of 113–177 ppbv) respectively with both species exhibiting an annual cycle of late-winter to early-spring maxima and summer minima. The absence of a broad summer O3 peak differs from previously-reported high altitude sites in the western US. The highest monthly-averaged O3 and CO mixing ratios relative to the 5-year monthly means were seen in fall 2002 and spring 2003 with increased O3 and CO of 10 % and 25 % respectively. These increases correspond to anomalously-high values reported at other Northern Hemisphere sites and are attributed to fires in the Russian Federation. Air mass back trajectory analysis is used to associate the mean enhancements of O3 and CO with trans-Pacific transported or North American air masses relative to the Pacific background. Mean values of the enhancements for March to June were 6 ppbv and 16 ppbv for O3 and CO respectively. In summers 2002–2006, higher CO and O3 mixing ratios were always observed in North American air masses and this relative enhancement co-varied for each year with the western US and Canada total wildfire area. The greatest enhancements in O3 and CO were seen in 2004, a record year for forest fires in Alaska and the Yukon Territory. In August 2004, average O3 and CO mixing ratios were 13 and 44 ppbv above background values.
Polarisation in the auroral red line during coordinated EISCAT Svalbard Radar/optical experiments
Authors: Barthélémy M. , Lilensten J. , Pitout F. , Simon Wedlund C. , Thissen R. , Lorentzen D. , Sigernes F. , Moen J. , Gronoff G. , McCrea I. , Rothkael H. , Ménager H. , Aruliah A.
Published: June 2011

Abstract. The polarisation of the atomic oxygen red line in the Earth's thermosphere is observed in different configurations with respect to the magnetic field line at high latitude during several coordinated Incoherent Scatter radar/optical experiment campaigns. When pointing northward with a line-of-sight nearly perpendicular to the magnetic field, we show that, as expected, the polarisation is due to precipitated electrons with characteristic energies of a few hundreds of electron Volts. When pointing toward the zenith or southward with a line-of-sight more parallel to the magnetic field, we show that the polarisation practically disappears. This confirms experimentally the predictions deduced from the recent discovery of the red line polarisation. We show that the polarisation direction is parallel to the magnetic field line during geomagnetic activity intensification and that these results are in agreement with theoretical work.
Effect of ocean acidification on otolith development in larvae of a tropical marine fish
Authors: Munday P. L. , Hernaman V. , Dixson D. L. , Thorrold S. R.
Published: June 2011

Abstract. Calcification in many invertebrate species is predicted to decline due to ocean acidification. The potential effects of elevated CO2 and reduced carbonate saturation state on other species, such as fish, are less well understood. Fish otoliths (earbones) are composed of aragonite, and thus, might be susceptible to either the reduced availability of carbonate ions in seawater at low pH, or to changes in extracellular concentrations of bicarbonate and carbonate ions caused by acid-base regulation in fish exposed to high pCO2. We reared larvae of the clownfish Amphiprion percula from hatching to settlement at three pHNBS and pCO2 levels (control: ~pH 8.15 and 404 μatm CO2; intermediate: pH 7.8 and 1050 μatm CO2; extreme: pH 7.6 and 1721 μatm CO2) to test the possible effects of ocean acidification on otolith development. There was no effect of the intermediate treatment (pH 7.8 and 1050 μatm CO2) on otolith size, shape, symmetry between left and right otoliths, or otolith elemental chemistry, compared with controls. However, in the more extreme treatment (pH 7.6 and 1721 μatm CO2) otolith area and maximum length were larger than controls, although no other traits were significantly affected. Our results support the hypothesis that pH regulation in the otolith endolymph can lead to increased precipitation of CaCO3 in otoliths of larval fish exposed to elevated CO2, as proposed by an earlier study, however, our results also show that sensitivity varies considerably among species. Importantly, our results suggest that otolith development in clownfishes is robust to even the more pessimistic changes in ocean chemistry predicted to occur by 2100.
A coupled climate model simulation of Marine Isotope Stage 3 stadial climate
Authors: Brandefelt J. , Kjellström E. , Näslund J.-O. , Strandberg G. , Voelker A. H. L. , Wohlfarth B.
Published: June 2011

Abstract. We present a coupled global climate model (CGCM) simulation, integrated for 1500 yr to quasi-equilibrium, of a stadial (cold period) within Marine Isotope Stage 3 (MIS 3). The simulated Greenland stadial 12 (GS12; ~44 ka BP) annual global mean surface temperature (Ts) is 5.5 °C lower than in the simulated recent past (RP) climate and 1.3 °C higher than in the simulated Last Glacial Maximum (LGM; 21 ka BP) climate. The simulated GS12 is evaluated against proxy data and previous modelling studies of MIS3 stadial climate. We show that the simulated MIS 3 climate, and hence conclusions drawn regarding the dynamics of this climate, is highly model-dependent. The main findings are: (i) Proxy sea surface temperatures (SSTs) are higher than simulated SSTs in the central North Atlantic, in contrast to earlier simulations of MIS 3 stadial climate in which proxy SSTs were found to be lower than simulated SST. (ii) The Atlantic Meridional Overturning Circulation (AMOC) slows down by 50 % in the GS12 climate as compared to the RP climate. This slowdown is attained without freshwater forcing in the North Atlantic region, a method used in other studies to force an AMOC shutdown. (iii) El-Niño-Southern Oscillation (ENSO) teleconnections in mean sea level pressure (MSLP) are significantly modified by GS12 and LGM forcing and boundary conditions. (iv) Both the mean state and variability of the simulated GS12 is dependent on the equilibration. The annual global mean Ts only changes by 0.10 °C from model years 500–599 to the last century of the simulation, indicating that the climate system may be close to equilibrium already after 500 yr of integration. However, significant regional differences between the last century of the simulation and model years 500–599 exist. Further, the difference between simulated and proxy SST is reduced from model years 500–599 to the last century of the simulation. The results of the ENSO variability analysis is also shown to depend on the equilibration.