bluuebunny/crossref_metadata_2025 huggingface dataset:
A Phase-Field Model Coupled with Lattice Kinetics Solver for Modeling Crystal Growth in Furnaces
Authors: Lin Guang , Bao Jie , Xu Zhijie , Tartakovsky Alexandre M. , Henager Charles H.
Published: July 2013

In this study, we present a new numerical model for crystal growth in a vertical solidification system. This model takes into account the buoyancy induced convective flow and its effect on the crystal growth process. The evolution of the crystal growth interface is simulated using the phase-field method. A semi-implicit lattice kinetics solver based on the Boltzmann equation is employed to model the unsteady incompressible flow. This model is used to investigate the effect of furnace operational conditions on crystal growth interface profiles and growth velocities. For a simple case of macroscopic radial growth, the phase-field model is validated against an analytical solution. The numerical simulations reveal that for a certain set of temperature boundary conditions, the heat transport in the melt near the phase interface is diffusion dominant and advection is suppressed.
What Do Clinicians Think about Hip Precautions following Total Hip Replacement?
Authors: Coole Carol , Edwards Claire , Brewin Catherine , Drummond Avril
Published: July 2013

Introduction:

Hip precautions are routinely recommended by occupational therapists to reduce the risk of dislocation following total hip replacement. The purpose of this study was to report the views and experiences of clinicians on the use of hip precautions with this client group.

Method:

Data were gathered from six National Health Service trusts, through 16 semi-structured telephone interviews. Participants included occupational therapists, physiotherapists, surgeons and nurses and data were analysed thematically.

Results:

Themes identified were: the rationale for, and disadvantages of, routine hip precautions and issues in the consistency of their application; the barriers and facilitators to relaxing hip precautions and the process and impact of changing practice; the contextual factors of service change and support for further research.

Conclusion:

There is variation in the views of clinicians regarding hip precautions due to differences in surgical opinion and lack of evidence as to whether precautions affect the risk of dislocation. Relaxing the routine provision of hip precautions is perceived to have an impact on patient recovery and satisfaction, the role and skill mix of therapy services, length of hospital stay and resource use. Trials are urgently required to investigate the effect of hip precautions on patient and surgical outcomes.
What Actually Informs Practice: Occupational Therapists' Views of Evidence
Authors: Robertson Linda , Graham Fiona , Anderson Jane
Published: July 2013

Introduction:

This research aims to explore what New Zealand occupational therapists consider ‘evidence’ to be and how the search for evidence is accomplished in their practice.

Method:

Semi-structured interviews were conducted with 14 therapists who had shown variations in comfort levels with locating and implementing evidence.

Findings:

Four themes emerged from the data: (1) finding evidence to support practice: informal quick methods were favoured; (2) the nature of available evidence: evidence was considered to be of limited value in practice as the context of the research was often very different to the context of local practice; (3) the organisational influences: the culture of the work environment played a key role in the dissemination of knowledge and (4) the importance of evidence: the need to use evidence to support practice was appreciated by most therapists. In general, using reliable resources was regarded as key to evidence-based practice with availability of resources, therefore, deemed essential.

Conclusion:

Therapists value trustworthy research information that is pre-digested and can be readily used in practice. Where there is limited research evidence, the focus should be on the generation and dissemination of information from critical reflections on practice.
Forum: Die rot-grüne Gesundheitsreform: Modernisierung als Umverteilung
Authors: Rakowitz Nadja
Published: July 2013

First paragraph

Das Gesundheitswesen ist – nicht nur in Deutschland – ein bedeutender ökonomischer Faktor. Mit einem Anteil von ca. zehn Prozent des BIP (ca. 250 Milliarden Euro Umsatz) liegt der Gesundheitssektor deutlich über dem Anteil der Kraftfahrzeugindustrie (vgl. Paetow 2002: 17). Trotz dieser im internationalen Vergleich relativ hohen Ausgaben hat der Sachverständigenrat für die Konzertierte Aktion im Gesundheitswesen im Jahr 2001 Über-, Unter- und Fehlversorgung im deutschen Gesundheitswesen festgestellt (vgl. Sachverständigenrat 2000 / 2001). Dabei sind die Ausgaben für Gesundheitsversorgung nur absolut gestiegen, in Relation zum BIP in den letzten 20 Jahren aber konstant geblieben. Die Beiträge zur Gesetzlichen Krankenversicherung (GKV) steigen wegen mangelnder Einnahmen, die auf die hohe Arbeitslosigkeit und die drastisch gesunkene bereinigte Lohnquote zurückzuführen sind. Trotzdem hat sich die These von der »Kosten-explosion« nicht nur in der politischen Klasse und bei den Arbeitgebern, sondern – so scheint es zumindest – auch in großen Teilen der Bevölkerung so weit zu einem »ökonomischen Faktum« verfestigt, dass eine »Reform« des Gesundheitswesens mit dem Zweck der Senkung der Beitragssätze geradezu Sachzwangcharakter bekommen hat.
Overcoming Rent by Using Rent: The Challenge of Development
Authors: Elsenhans Hartmut
Published: July 2013

The article tracks the current crises of development theory in the understanding of the differences in political economy of developed capitalism (rising mass incomes) and underdeveloped economies (labor surplus and rent). The challenge of rents consists in spontaneous tendencies of its wasteful use for blocking development, which do, however, not exclude its possible use for the elimination of marginality.

A convoy model of globalization with world wide full employment and an underconsumptionist model are distinguished. In the convoy model, an under-developed economy reaches full employment on the basis of devaluation. In the underconsumptionist model, devaluation-driven export-oriented industrialization does because of its too small impact not lead to the scarcity of average skilled labor. Leading industrialized countries react to the new competitiveness of catching-up economies through the implementation of wage restraint and industrial policies. Rent bounces back. Establishing a convoy model requires development policies characterized by an intelligent mix of rising mass incomes, reduced rents and devaluation-driven industrialization together with state support for investment.
Nichts als Strohfeuer? Eine kritische Analyse des wirtschaftspolitischen Assignments im »Neuen Konsens« mit Hilfe eines makroökonometrischen Politiksimulationsmodells der Schweizer Volkswirtschaft
Authors: Hartwig Jochen
Published: July 2013

The paper is concerned with the traditional »assignment« to be found in many textbooks that holds central bankers responsible for inflation – and inflation only – while government politicians are recommended to care for the short-term stabilisation of the economy (or not to interfere at all, respectively). Building on monetary and fiscal policy simulations done with a macroeconometric model of the Swiss economy, possible long-term real effects of monetary policy are established. Also, a potential role for fiscal policy in the control of inflation is located. Since macroeconometric modelling is now widely regarded as being outmoded, special care is taken to argue that neither the seminal »Lucas critique« nor more recent time series approaches can be said to have overridden the traditional approach.
Kontroversen in der internationalen Währungspolitik. Retrospektive zu Keynes-White-Boughton und IMF
Authors: Muchlinski Elke
Published: July 2013

This paper provides textual evidence that Boughton's interpretation of Keynes's proposals for shaping the international monetary system of the post-war period misses the point. I want to investigate two points which contradict Boughton's interpretation published by the International Monetary Fund. Boughton states that White won the battle against Keynes because White was determined to create a multilateral system whereas Keynes favoured bilateral financial support to Britain by the U.S.A. I submit that Keynes's view on the function of the International Clearing Union (I.C.U.) was first of all to encourage both creditor and debtor countries to avoid trade imbalances. Second, as Keynes mentioned, the I.C.U. was not to be implemented as a »multiplicity of bilateral arrangements«. Here we find the thrust of his view of the post-war period – avoiding bilateral arrangements because he believed that bilateralism could cause a new war.
Gewinn- und/oder Kapitalbeteiligungen – ökonomische Utopie oder Notwendigkeit?
Authors: Bontrup Heinz-J.
Published: July 2013

The article deals with profit and gain sharing and employee capital sharing plans. Non-material forms of participation are mainly concerned with shop floor participation. Material participation, on the other hand, focuses on wage and salary earners who share in their company's profits and/or in other firm capital. Under such a scheme, the profit is divided between shareholders and employees, thereby enabling the latter to earn a higher income and to accumulate wealth. The paper begins with a description of the complex rationale for profit and gain sharing and capital sharing plans. It will also look at problems resulting from a microeconomic perspective. Furthermore, the article deals with the requirements for genuine profit and gain and capital sharing plans, as they exist in practice. Finally the consequences of such a scheme for the economy as a whole will be discussed in detail.
Failed Translations: Textuality of Capital against Walter Benjamin's »The Task of the Translator«
Authors: Marder Michael
Published: July 2013

In order to stage a sustained encounter between literary theory and Marxian political economy, this paper initiates a dialogue between Walter Benjamin's »The Task of the Translator« on one hand, and Marx's Capital, on the other. I will theorize the two-fold transition from the language of labor to value to price in the latter work as an exercise in economic translation haunted by and predicated upon the untranslatability of use-value, or pure difference. In light of this initial outline, I will contend that the specific intentionality of capital, the predominance of the »pure language« of value, and the discursive construction of mainstream economics violate the immanent grounding of economic and non-economic systems of signification.
Multi-decadal variations of atmospheric aerosols from 1980 to 2009: sources and regional trends
Authors:   Mian Chin, Diehl T. , Tan Q. , Prospero J. M. , Kahn R. A. , Remer L. A. , Yu H. , Sayer A. M. , Bian H. , Geogdzhayev I. V. , Holben B. N. , Howell S. G. , Huebert B. J. , Hsu N. C. , Kim D. , Kucsera T. L. , Levy R. C. , Mishchenko M. I. , Pan X. , Quinn P. K. , Schuster G. L. , Streets D. G. , Strode S. A. , Torres O. , Zhao X.-P.
Published: July 2013

Abstract. Aerosol variations and trends over different land and ocean regions during 1980–2009 are analyzed with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model and observations from multiple satellite sensors and ground-based networks. Excluding time periods with large volcanic influences, the tendency of aerosol optical depth (AOD) and surface concentration over polluted land regions is consistent with the anthropogenic emission changes. The largest reduction occurs over Europe, and regions in North America and Russia also exhibit reductions. On the other hand, East Asia and South Asia show AOD increases, although relatively large amount of natural aerosols in Asia makes the total changes less directly connected to the pollutant emission trends. Over major dust source regions, model analysis indicates that the dust emissions over the Sahara and Sahel respond mainly to the near-surface wind speed, but over Central Asia they are largely influenced by ground wetness. The decreasing dust trend in the tropical North Atlantic is most closely associated with the decrease of Sahel dust emission and increase of precipitation over the tropical North Atlantic, likely driven by the sea surface temperature increase. Despite significant regional trends, the model-calculated global annual average AOD shows little changes over land and ocean in the past three decades, because opposite trends in different regions cancel each other in the global average. This highlights the need for regional-scale aerosol assessment, as the global average value conceals regional changes, and thus is not sufficient for assessing changes in aerosol loading.
Increased absorption by giant aerosol particles over the Gangetic–Himalayan region
Authors: Manoharan V. S. , Kotamarthi R. , Feng Y. , Cadeddu M. P.
Published: July 2013

Abstract. Each atmospheric aerosol type has distinctive light-absorption characteristics related to its physical/chemical properties. Climate models treat black carbon as the light-absorbing component of all carbonaceous atmospheric aerosols. Most absorbing aerosols are assumed to be <1 μm in diameter (sub-micron). Here we present results from a recent field study in India, primarily during the post-monsoon season (October–November), suggesting the presence of absorbing aerosols sized 1–10 μm. Absorption due to super-micron-sized particles was nearly 30% greater than that due to smaller particles. Periods of increased absorption by larger particles ranged from a week to a month. Radiative forcing calculations under clear-sky conditions show that super-micron particles account for nearly 44% of the total aerosol-forcing. The origin of the large aerosols is unknown, but meteorological conditions indicate that they are of local origin. Such economic and habitation conditions exist throughout much of the developing world. Hence, large absorbing particles could be an important component of the regional-scale atmospheric-energy balance.
Comparing ECMWF AOD with AERONET observations at visible and UV wavelengths
Authors: Cesnulyte V. , Lindfors A. V. , Pitkänen M. R. A. , Lehtinen K. E. J. , Morcrette J. J. , Arola A.
Published: July 2013

Abstract. This paper presents validation results of the ECMWF Integrated Forecasting System MACC re-analysis aerosol optical depth (AOD) for the period 2003–2006. We evaluate the MACC AOD at a UV wavelength (340 nm) and at mid-visible (500 and 550 nm) by comparing against ground-based AERONET measurements at 12 sites. The AERONET sites cover various parts of the globe and are categorized in three groups: urban/anthropogenic, biomass burning and dust, depending on the typically dominating aerosol type. This is the first time when a global model such as the ECMWF is evaluated for the performance of AOD at a UV wavelength. The results show that the MACC system generally provides a good representation of the AOD on a monthly basis, showing a realistic seasonal cycle. The model is mostly able to capture major dust load events and also the peak months of biomass burning correctly. For Kanpur and Solar Village, however, the model overestimates the AOD during the monsoon period when the aerosol load is generally low. When comparing hourly AOD values, the model-measurement agreement is better for biomass burning and dust sites than for urban sites, with an average correlation coefficient around 0.90 for biomass burning sites, around 0.77 for dust sites, and below 0.70 for urban sites. The AOD at 500 nm averaged over all sites shows only a small systematic difference between modeled and measured values, with a relative mean bias of 0.02. However, for the AOD at 340 nm the relative mean bias is −0.2. All sites included in the study show a relative mean bias at 340 nm smaller (or more negative) than that at 500 nm, indicating a strong wavelength-dependence in the performance of the AOD in the MACC system. A comparison against fine and coarse mode AOD of the AERONET indicates that this has to do with the size distribution of the model: generally, the ECMWF model overestimates the contribution by coarse mode particles.
Longitudinal hot-spots in the mesospheric OH variations due to energetic electron precipitation
Authors: Andersson M. E. , Verronen P. T. , Rodger C. J. , Clilverd M. A. , Wang S.
Published: July 2013

Abstract. Using Microwave Limb Sounder (MLS/Aura) and Medium Energy Proton and Electron Detector (MEPED/POES) observations between 2005–2009, we study the longitudinal response of nighttime mesospheric OH to radiation belt electron precipitation. Our analysis concentrates on geomagnetic latitudes from 55–72° N/S and altitudes between 70–78 km. The aim of this study is to better assess the spatial distribution of electron forcing, which is important for more accurate modeling of its atmospheric and climate effects. In the Southern Hemisphere, OH data show a hot-spot at longitudes between 150° W–30° E, i.e., poleward of the Southern Atlantic Magnetic Anomaly (SAMA) region. In the Northern Hemisphere, energetic electron precipitation–induced OH variations are more equally distributed with longitude. This longitudinal behaviour of OH can also be identified using Empirical Orthogonal Function analysis, and is found to be similar to that of MEPED–measured electron fluxes. The main difference is in the SAMA region, where MEPED appears to measure very large electron fluxes while MLS observations show no enhancement of OH. This indicates that in the SAMA region the MEPED observations are not related to precipitating electrons, at least not at energies > 100 keV, but related to instrument contamination. Analysis of selected OH data sets for periods of different geomagnetic activity levels shows that the longitudinal OH hot-spot south of the SAMA (the Antarctic Peninsula region) is partly caused by strong, regional electron forcing, although atmospheric conditions also seem to play a role. This OH hot-spot is even seen weakly during periods of lower geomagnetic activity, which suggest that there is a steady drizzle of electrons affecting the atmosphere, due to the Earth's magnetic field being weaker in this region.
A review of turbulence measurements using ground-based wind lidars
Authors: Sathe A. , Mann J.
Published: July 2013

Abstract. A review of turbulence measurements using ground-based wind lidars is carried out. Works performed in the last 30 yr, i.e. from 1972–2012 are analyzed. More than 80% of the work has been carried out in the last 15 yr, i.e. from 1997–2012. New algorithms to process the raw lidar data were pioneered in the first 15 yr, i.e. from 1972–1997, where standard techniques could not be used to measure turbulence. Obtaining unfiltered turbulence statistics from the large probe volume of the lidars has been and still remains the most challenging aspect. Until now, most of the processing algorithms that have been developed have shown that by combining an isotropic turbulence model with raw lidar measurements, we can obtain unfiltered statistics. We believe that an anisotropic turbulence model will provide a more realistic measure of a turbulence statistic. Future development in algorithms will depend on whether the unfiltered statistics can be obtained without the aid of any turbulence model. With the tremendous growth of the wind energy sector, we expect that lidars will be used for turbulence measurements much more than ever before.
Kalman filter physical retrieval of geophysical parameters from high temporal resolution geostationary infrared radiances: the case of surface emissivity and temperature
Authors: Masiello G. , Serio C. , De Feis I. , Amoroso M. , Venafra S. , Trigo I. F. , Watts P.
Published: July 2013

Abstract. The high temporal resolution of the data acquisition by geostationary satellites and their capability to resolve the diurnal cycle are a precious source of information which could be suitably used to retrieve geophysical parameters. Currently this information is for the most part considered as uncorrelated, both in space and time: each pixel is treated independently from its neighbors and the present events are not linked to past or future ones. In this paper we develop a Kalman filter approach to apply spatial and temporal constraints to estimate the geophysical parameters from radiance measurements made from geostationary platforms. We apply the new strategy to a particular case study, i.e. the retrieval of emissivity and surface temperature from SEVIRI (Spinning Enhanced Visible and InfraRed Imager) observations over a target area encompassing the Iberian Peninsula and Northwestern Africa. The retrievals are then compared with in situ data, and other similar satellite products.
Timing of fire relative to seed development may enable non-serotinous species to recolonize from the aerial seed banks of fire-killed trees
Authors: Michaletz S. T. , Johnson E. A. , Mell W. E. , Greene D. F.
Published: July 2013

Abstract. The existence of non-serotinous, non-sprouting species in fire regimes where serotiny confers an adaptive advantage is puzzling, particularly when these species recruit poorly from soil seed banks or from burn edges. In this paper, white spruce (Picea glauca (Moench) Voss) was used to show how the timing of fire relative to seed development may permit non-serotinous species to recolonize burned areas from the aerial seed banks of fire-killed trees. To estimate survival of seeds within closed cones during crown fires, cone heating was simulated using a one-dimensional conduction model implemented in a three-dimensional computational fluid dynamics fire behavior model. To quantify the area burned when germinable seed would be contained within closed cones during a mast year, empirical fire occurrence and seed development (germinability and cone opening) data were compared for multiple locations across the white spruce range. Approximately 12% of cones contained viable seed following crown fire simulations (0.072 m s−1 mean spread rate; 9147 kW m−1 mean intensity), and roughly half of the historical area burned resulted from fires that occurred when closed cones would contain germinable seed. Together, these results suggest that non-serotinous species may recolonize burned areas from in situ aerial seed banks, and that this may be an important cause of their existence in fire regimes to which they otherwise seem poorly suited.
Modelling drivers of mangrove propagule dispersal and restoration of abandoned shrimp farms
Authors: Di Nitto D. , Erftemeijer P. L. A. , van Beek J. K. L. , Dahdouh-Guebas F. , Higazi L. , Quisthoudt K. , Jayatissa L. P. , Koedam N.
Published: July 2013

Abstract. Propagule dispersal of four mangrove species Rhizophora mucronata, R. apiculata, Ceriops tagal and Avicennia officinalis in the Pambala–Chilaw Lagoon Complex (Sri Lanka) was studied by combining a hydrodynamic model with species-specific knowledge on propagule dispersal behaviour. Propagule transport was simulated using a finite-volume advection-diffusion model to investigate the effect of dispersal vectors (tidal flow, freshwater discharge and wind), trapping agents (retention by vegetation) and seed characteristics (buoyancy) on propagule dispersal patterns. Sensitivity analysis showed that smaller propagules, like the oval-shaped propagules of Avicennia officinalis, dispersed over larger distances and were most sensitive to changing values of retention by mangrove vegetation compared to larger, torpedo-shaped propagules of Rhizophora spp. and C. tagal. Directional propagule dispersal in this semi-enclosed lagoon with a small tidal range was strongly concentrated towards the edges of the lagoon and channels. Short distance dispersal appeared to be the main dispersal strategy for all four studied species, with most of the propagules being retained within the vegetation. Only a small proportion (max. 5%) of propagules left the lagoon through a channel connecting the lagoon with the open sea. Wind significantly influenced dispersal distance and direction once propagules entered the lagoon or adjacent channels. Implications of these findings for mangrove restoration were tested by simulating partial removal in the model of dikes around abandoned shrimp ponds to restore tidal hydrology and facilitate natural recolonisation by mangroves. The specific location of dike removal, (with respect to the vicinity of mangroves and independently suitable hydrodynamic flows), was found to significantly affect the resultant quantities and species of inflowing propagules and hence the potential effectiveness of natural regeneration. These results demonstrate the value of propagule dispersal modelling in guiding hydrological restoration efforts that aim to facilitate natural mangrove regeneration.
Dynamics of microbial communities during decomposition of litter from pioneering plants in initial soil ecosystems
Authors: Esperschütz J. , Zimmermann C. , Dümig A. , Welzl G. , Buegger F. , Elmer M. , Munch J. C. , Schloter M.
Published: July 2013

Abstract. In initial ecosystems, concentrations of all macro- and micronutrients can be considered as extremely low. Plant litter therefore strongly influences the development of a degrader's food web and is an important source for C and N input into soil in such ecosystems. In the present study, a 13C litter decomposition field experiment was performed for 30 weeks in initial soils from a post-mining area near the city of Cottbus (Germany). Two of this region's dominant but contrasting pioneering plant species (Lotus corniculatus L. and Calamagrostis epigejos L.) were chosen to investigate the effects of litter quality on the litter decomposing microbial food web in initially nutrient-poor substrates. The results clearly indicate the importance of litter quality, as indicated by its N content, its bioavailability for the degradation process and the development of microbial communities in the detritusphere and soil. The degradation of the L. corniculatus litter, which had a low C / N ratio, was fast and showed pronounced changes in the microbial community structure 1–4 weeks after litter addition. The degradation of the C. epigejos litter material was slow and microbial community changes mainly occurred between 4 and 30 weeks after litter addition to the soil. However, for both litter materials a clear indication of the importance of fungi for the degradation process was observed both in terms of fungal abundance and activity (13C incorporation activity)
Introduction to the project DUNE, a DUst experiment in a low Nutrient, low chlorophyll Ecosystem
Authors: Guieu C. , Dulac F. , Ridame C. , Pondaven P.
Published: July 2013

Abstract. The main goal of the project DUNE was to estimate the impact of atmospheric deposition on an oligotrophic ecosystem based on mesocosm experiments simulating strong atmospheric inputs of Aeolian dust. Atmospheric deposition is now recognized as a significant source of macro- and micro-nutrients for the surface ocean, but the quantification of its role on the biological carbon pump is still poorly determined. We proposed in DUNE to investigate the role of atmospheric inputs on the functioning of an oligotrophic system particularly well adapted to this kind of study: the Mediterranean Sea. The Mediterranean Sea – etymologically, sea surrounded by land – is submitted to atmospheric inputs that are very variable both in frequency and intensity. During the thermal stratification period, only atmospheric deposition is prone to fertilize Mediterranean surface waters which has become very oligotrophic due to the nutrient depletion (after the spring bloom). This paper describes the objectives of DUNE and the implementation plan of a series of mesocosms experiments during which either wet or dry and a succession of two wet deposition fluxes of 10 g m−2 of Saharan dust have been simulated. After the presentation of the main biogeochemical initial conditions of the site at the time of each experiment, a general overview of the papers published in this special issue is presented, including laboratory results on the solubility of trace elements in erodible soils in addition to results from the mesocosm experiments. Our mesocosm experiments aimed at being representative of real atmospheric deposition events onto the surface of oligotrophic marine waters and were an original attempt to consider the vertical dimension in the study of the fate of atmospheric deposition within surface waters. Results obtained can be more easily extrapolated to quantify budgets and parameterize processes such as particle migration through a "captured water column". The strong simulated dust deposition events were found to impact the dissolved concentrations of inorganic dissolved phosphorus, nitrogen, iron and other trace elements. In the case of Fe, adsorption on sinking particles yields a decrease in dissolved concentration unless binding ligands were produced following a former deposition input and associated fertilization. For the first time, a quantification of the C export induced by the aerosol addition was possible. Description and parameterization of biotic (heterotrophs and autotrophs, including diazotrophs) and abiotic processes (ballast effect due to lithogenic particles) after dust addition in sea surface water, result in a net particulate organic carbon export in part controlled by the "lithogenic carbon pump".
The East Asian winter monsoon variability in response to precession and inter-hemispheric heat balance
Authors: Yamamoto M. , Sai H. , Chen M.-T. , Zhao M.
Published: July 2013

Abstract. The response of Asian monsoon variability to orbital forcing is still unclear, and all hypotheses are controversial. We present a record of the sea surface temperature difference (ΔSST) between the South China Sea and the other Western Pacific Warm Pool regions as a proxy for the intensity of the Asian winter monsoon, because the winter cooling of the South China Sea is caused by the cooling of surface water at the northern margin and the southward advection of cooled water due to winter monsoon winds. The ΔSST showed significant precession cycles during the last 150 kyr. In the precession cycle, the maximum winter monsoon intensity shown by the ΔSST corresponded to the May perihelion and was delayed behind the maximum ice volume. The East Asian winter monsoon was anti-phase with the Indian summer monsoon and the summer monsoon precipitation in central Japan. The timing of the maximum phase of the East Asian winter monsoon was different from previous results in terms of the March perihelion (ice volume maxima) and June perihelion (minimum of Northern Hemisphere winter insolation). We infer that the variation of the East Asian winter monsoon was caused by a physical mechanism of inter-hemispheric heat balance. The East Asian winter monsoon was intensified by the Northern Hemisphere cooling, which was caused by the combined effect of cooling by the ice volume forcing and the decrease in winter insolation, or by decreased heat transfer from the Southern Hemisphere to the Northern Hemisphere owing to the weak Indian summer monsoon at the May perihelion.
In-flight calibration of Hot Ion Analyser onboard Cluster
Authors: Blagau A. , Dandouras I. , Barthe A. , Brunato S. , Facskó G. , Constantinescu V.
Published: July 2013

Abstract. The Hot Ion Analyser (HIA), part of the Cluster Ion Spectrometry experiment, has the objective to measure the three-dimensional velocity distributions of ions. Due to a variety of factors (exposure to radiation, detector fatigue and aging, changes in the operating parameters etc.), the particles detection efficiency changes over time, prompting for continuous in-flight calibration. This is achieved by comparing the HIA data with the data provided by the WHISPER experiment on magnetosheath intervals, for the high sensitivity section of the instrument, or solar wind intervals, for the low sensitivity section. The paper presents in detail the in-flight calibration methodology, reports on the work carried out for calibrating HIA and discusses plans to extend this activity in order to ensure the instrument highest data accuracy.
Near equipment magnetic field verification and scaling
Authors: Pudney M. A. , Carr C. M. , Schwartz S. J. , Howarth S. I.
Published: July 2013

Abstract. Magnetic field measurements are essential to the success of many scientific space missions. Outside of the Earth's magnetic field the biggest potential source of magnetic field contamination of these measurements is emitted by the spacecraft. Spacecraft magnetic cleanliness is enforced through the application of strict ground verification requirements for spacecraft equipment and instruments. Due to increasingly strict AC magnetic field requirements, many spacecraft units cannot be verified on the ground using existing techniques. These measurements must instead be taken close to the equipment under test (EUT) and then extrapolated. A traditional dipole power law of −3 (with a field fall-off proportional to r−3) cannot be applied at these close distances without risk of underestimating the field emitted by the EUT, but we demonstrate that a power law of −2 is too conservative. We propose a compromise that uses a power law of −2 up to a distance equal to 3 times the unit size, beyond which a dipole power law can be applied. When extrapolating from a distance of 0.20 to 1.00 m from the centre of a 0.20 m wide EUT, we demonstrate that this method avoids an underprediction of the field, and is at least twice as accurate as performing the extrapolation with a fixed power law of −2.
Controls on oxygen dynamics in a riverine salt-wedge estuary – a three-dimensional model of the Yarra River estuary, Australia
Authors: Bruce L. C. , Cook P. L. M. , Teakle I. , Hipsey M. R.
Published: July 2013

Abstract. Oxygen depletion in estuarine waters is an important factor governing water quality and ecological health. A complex and dynamic balance of physical and biogeochemical factors drive the extent and persistence of hypoxia and anoxia making it difficult to predict. An increased understanding of the effect of changing flow regimes and temperature on patterns of estuarine oxygen depletion is required to support ongoing management. Coupled physical and biogeochemical models have been applied to study the interaction of physical processes and seasonal hypoxia, however, application to riverine estuaries with tight curvature and more sporadic periods of oxygen depletion is rare. In this study we apply a finite volume 3-D hydrodynamic-biogeochemical model (TUFLOW-FV–FABM) to the Yarra River estuary, Australia, in order to predict the extent of salt-wedge intrusion and consequent patterns of oxygen depletion. The predictive capacity of the model was evaluated using a series of model verification metrics and the results evaluated to determine the dominant mechanisms affecting salt-wedge position and the extent and persistence of anoxia and hypoxia. Measures of model fit indicated that the model reasonably captured the strength of stratification and the position and extent of the salt wedge (r2 ~ 0.74). The extent of the salt wedge intrusion was controlled by riverine flow and the strength of stratification or mixing dominated by topographical features corresponding to areas of tight curvature ("horseshoe" bends). The model predicted that the extent of anoxic waters generally mimicked the extent of the salt wedge (r2 ~ 0.65) increasing during periods of low flow and reduced following episodic high flow events. The results showed two sporadically isolated "hot spots" of anoxia, the first downstream of the horseshoe bend and the second downstream of a sill. Simulated oxygen concentrations indicated that whilst a threshold salt wedge intrusion was a requirement of oxygen depletion, temperature was critical in determining the extent of hypoxia and anoxia in the estuary. These findings highlight the importance of how seasonal changes in flow events and environmental flow management can impact on estuarine oxygen depletion in a warming climate. This study provides an improved understanding of the controls on hypoxia and anoxia in riverine estuaries, which is essential to support improved prediction of nutrient dynamics and ecological heath.
Lightning flash multiplicity in Eastern Mediterranean thunderstorms
Authors: Yair Y. , Shalev S. , Erlich Z. , Agrachov A. , Katz E. , Saaroni H. , Price C. , Ziv B.
Published: July 2013

Abstract. Cloud-to-ground lightning flashes usually consist of one or several strokes coming in very short temporal succession and close spatial proximity. The common method for converting stroke data into flashes is using the National Lightning Detection Network (NALDN) thresholds of maximum temporal separation of 0.5 s and maximum lateral distance of 10 km radius between successive strokes. In the present study, we tested a location-based algorithm with several spatial and temporal ranges, and analyzed stroke data obtained by the Israel Lightning Location System (ILLS) during one year (1 August 2009–31 July 2010). We computed the multiplicity, the percentage of single stroke flashes and the geographical distribution of single vs. multiple-stroke flashes for thunderstorms in the Eastern Mediterranean region. Results show that for the NALDN thresholds, the percentage of single stroke flashes in Israel was 37% and the average multiplicity was 1.7. We re-analyzed the data with a spatial range that equals twice the ILLS location error and shorter times. For the new thresholds of maximum distance of 2.5 km and maximum allowed temporal separation of 0.2 s we find that the mean multiplicity of negative CGs is lowered to 1.4 and find a percentage of 58% of single stroke flashes. A unique severe storm from 30 October 2009 is analyzed and compared to the annual average of 2009/10, showing that large deviations from the mean values can occur in specific events.
Comment on "Comparative study on earthquake and ground based transmitter induced radiation belt electron precipitation at middle latitude" by Sideropoulos et al. (2011)
Authors: Sauvaud J.-A. , Parrot M. , Slominska E.
Published: July 2013

Abstract. We show that many, if not all, electron bursts claimed to be earthquake precursors by Sideropoulos et al. (2011) are due to the cyclotron resonance of electrons with monochromatic waves from VLF transmitters. The geographic distribution of the VLF-related electron bursts is established during a period in 2007, when the powerful NWC transmitter is off.
Fully integrated physically-based numerical modelling of impacts of groundwater extraction on surface and irrigation-induced groundwater interactions: case study Lower River Murray, Australia
Authors: Alaghmand S. , Beecham S. , Hassanli A.
Published: July 2013

Abstract. Combination of reduction in the frequency, duration and magnitude of natural floods, rising saline water-table in floodplains and excessive evapotranspiration have led to an irrigation-induced groundwater mound forced the naturally saline groundwater onto the floodplain in the Lower River Murray. It is during the attenuation phase of floods that these large salt accumulations are likely to be mobilised and will discharge into the river. The Independent Audit Group for Salinity highlighted this as the most significant risk in the Murray–Darling Basin. South Australian government and catchment management authorities have developed salt interception schemes (SIS). This is to pump the highly saline groundwater from the floodplain aquifer to evaporation basins in order to reduce the hydraulic gradient that drives the regional saline groundwater towards the River Murray. This paper investigates the interactions between a river (River Murray in South Australia) and a saline semi-arid floodplain (Clarks Floodplain) significantly influenced by groundwater lowering (Bookpurnong SIS). Results confirm that groundwater extraction maintain a lower water-table and more fresh river water flux to the saline floodplain aquifer. In term of salinity, this may lead to less amount of solute stored in the floodplain aquifer. This occurs through two mechanisms; extracting some of the solute mass from the system and changing the floodplain groundwater regime from a losing to gaining one. Finally, it is shown that groundwater extraction is able to remove some amount of solute stored in the unsaturated zone and mitigate the floodplain salinity risk.
On the identification of Dragon Kings among extreme-valued outliers
Authors: Riva M. , Neuman S. P. , Guadagnini A.
Published: July 2013

Abstract. Extreme values of earth, environmental, ecological, physical, biological, financial and other variables often form outliers to heavy tails of empirical frequency distributions. Quite commonly such tails are approximated by stretched exponential, log-normal or power functions. Recently there has been an interest in distinguishing between extreme-valued outliers that belong to the parent population of most data in a sample and those that do not. The first type, called Gray Swans by Nassim Nicholas Taleb (often confused in the literature with Taleb's totally unknowable Black Swans), is drawn from a known distribution of the tails which can thus be extrapolated beyond the range of sampled values. However, the magnitudes and/or space–time locations of unsampled Gray Swans cannot be foretold. The second type of extreme-valued outliers, termed Dragon Kings by Didier Sornette, may in his view be sometimes predicted based on how other data in the sample behave. This intriguing prospect has recently motivated some authors to propose statistical tests capable of identifying Dragon Kings in a given random sample. Here we apply three such tests to log air permeability data measured on the faces of a Berea sandstone block and to synthetic data generated in a manner statistically consistent with these measurements. We interpret the measurements to be, and generate synthetic data that are, samples from α-stable sub-Gaussian random fields subordinated to truncated fractional Gaussian noise (tfGn). All these data have frequency distributions characterized by power-law tails with extreme-valued outliers about the tail edges.
A new method for continuous measurements of oceanic and atmospheric N2O, CO and CO2: performance of off-axis integrated cavity output spectroscopy (OA-ICOS) coupled to non-dispersive infrared detection (NDIR)
Authors: Arévalo-Martínez D. L. , Beyer M. , Krumbholz M. , Piller I. , Kock A. , Steinhoff T. , Körtzinger A. , Bange H. W.
Published: July 2013

Abstract. A new system for continuous, highly-resolved oceanic and atmospheric measurements of N2O, CO and CO2 is described. The system is based upon off-axis integrated cavity output spectroscopy (OA-ICOS) and a non-dispersive infrared analyzer (NDIR) both coupled to a Weiss-type equilibrator. Performance of the combined setup was evaluated by testing its precision, accuracy, long-term stability, linearity and response time. Furthermore, the setup was tested during two oceanographic campaigns in the equatorial Atlantic Ocean in order to explore its potential for autonomous deployment onboard voluntary observing ships (VOS). Improved equilibrator response times for N2O (2.5 min) and CO (45 min) were achieved in comparison to response times from similar chamber designs used by previous studies. High stability of the OA-ICOS analyzer was demonstrated by low optimal integration times of 2 and 4 min for N2O and CO respectively, as well as detection limits of < 40 ppt and precision better than 0.3 ppb Hz−1/2. Results from a direct comparison of the method presented here and well-established discrete methods for oceanic N2O and CO2 measurements showed very good consistency. The favorable agreement between underway atmospheric N2O, CO and CO2 measurements and monthly means at Ascension Island (7.96° S 14.4° W) further suggests a reliable operation of the underway setup in the field. The potential of the system as an improved platform for measurements of trace gases was explored by using continuous N2O and CO2 data to characterize the development of the seasonal equatorial upwelling in the Atlantic Ocean during two R/V Maria S. Merian cruises. A similar record of high-resolution CO measurements was simultaneously obtained offering for the first time the possibility of a comprehensive view on the distribution and emissions of these climate relevant gases on the area. The relatively simple underway N2O/CO/CO2 setup is suitable for long-term deployment on board of research and commercial vessels although potential sources of drift such as cavity temperature and further technical improvements towards automation still need to be addressed.
Influence of ice-sheet geometry and supraglacial lakes on seasonal ice-flow variability
Authors: Joughin I. , Das S. B. , Flowers G. E. , Behn M. D. , Alley R. B. , King M. A. , Smith B. E. , Bamber J. L. , van den Broeke M. R. , van Angelen J. H.
Published: July 2013

Abstract. Supraglacial lakes play an important role in establishing hydrological connections that allow lubricating seasonal meltwater to reach the base of the Greenland Ice Sheet. Here we use new surface velocity observations to examine the influence of supraglacial lake drainages and surface melt rate on ice flow. We find large, spatially extensive speedups concurrent with times of lake drainage, showing that lakes play a key role in modulating regional ice flow. While surface meltwater is supplied to the bed via a geographically sparse network of moulins, the observed ice-flow enhancement suggests that this meltwater spreads widely over the ice-sheet bed. We also find that the complex spatial pattern of speedup is strongly determined by the combined influence of bed and surface topography on subglacial water flow. Thus, modeling of ice-sheet basal hydrology likely will require knowledge of bed topography resolved at scales (sub-kilometer) far finer than existing data (several km).
Response of ice cover on shallow lakes of the North Slope of Alaska to contemporary climate conditions (1950–2011): radar remote sensing and numerical modeling data analysis
Authors: Surdu C. M. , Duguay C. R. , Brown L. C. , Fernández Prieto D.
Published: July 2013

Abstract. Air temperature and winter precipitation changes over the last five decades have impacted the timing, duration, and thickness of the ice cover on Arctic lakes as shown by recent studies. In the case of shallow tundra lakes, many of which are less than 3 m deep, warmer climate conditions could result in thinner ice covers and consequently, to a smaller fraction of lakes freezing to their bed in winter. However, these changes have not yet been comprehensively documented. The analysis of a 20 yr time series of ERS-1/2 synthetic aperture radar (SAR) data and a numerical lake ice model were employed to determine the response of ice cover (thickness, freezing to the bed, and phenology) on shallow lakes of the North Slope of Alaska (NSA) to climate conditions over the last six decades. Analysis of available SAR data from 1991–2011, from a sub-region of the NSA near Barrow, shows a reduction in the fraction of lakes that freeze to the bed in late winter. This finding is in good agreement with the decrease in ice thickness simulated with the Canadian Lake Ice Model (CLIMo), a lower fraction of lakes frozen to the bed corresponding to a thinner ice cover. Observed changes of the ice cover show a trend toward increasing floating ice fractions from 1991 to 2011, with the greatest change occurring in April, when the grounded ice fraction declined by 22% (α = 0.01). Model results indicate a trend toward thinner ice covers by 18–22 cm (no-snow and 53% snow depth scenarios, α = 0.01) during the 1991–2011 period and by 21–38 cm (α = 0.001) from 1950–2011. The longer trend analysis (1950–2011) also shows a decrease in the ice cover duration by ∼24 days consequent to later freeze-up dates by 5.9 days (α = 0.1) and earlier break-up dates by 17.7–18.6 days (α = 0.001).