bluuebunny/crossref_metadata_2025 huggingface dataset:
Untersuchung von asynchronen Timing-Strategien für digitale Subthreshold-Schaltungen
Authors: Lotze N. , Ortmanns M. , Manoli Y.
Published: April 2010

Abstract. Eine der großen Herausforderungen beim Betrieb von Schaltungen bei extrem niedrigen Versorgungsspannungen ist die starke Zunahme des Einflusses zufälliger Prozessvariationen auf die Verzögerungszeiten der Gatter. Dies erfordert sehr hohe Sicherheitsmargen im Timing der Schaltungen, was zu einer deutlichen Verringerung der Geschwindigkeit und einem Anstieg der Energie pro Operation führt. Asynchrone Schaltungstechniken, die durch ihre Kodierung das Ende einer Operation detektieren können, sind daher bei dieser Anwendung eine interessante Alternative. In dieser Veröffentlichung werden die notwendigen Sicherheitsmargen in Delay-Line basierten Subthreshold-Schaltungen diskutiert und mögliche asynchrone Dual-Rail Entwurfsmethoden vorgestellt. Transistor-Level Simulationsergebnisse für einen einfachen, in den diskutierten Techniken realisierten Zähler werden vorgestellt, um die Funktionsfähigkeit dieser Techniken im Subthreshold-Bereich zu demonstrieren. Multiplizier mit unterschiedlicher Wortbreite dienen als Beispiel für eine komplexere Schaltung, welche bezüglich Geschwindigkeit, Energiebedarf und Flächenaufwand mit einer entsprechenden Standard-Realisierung verglichen wird, was abschließend eine Aussage darüber zulässt, wann die untersuchten Techniken gewinnbringend eingesetzt werden können.
Measurement of the transient shielding effectiveness of shielding cabinets
Authors: Herlemann H. , Koch M.
Published: April 2010

Abstract. Recently, new definitions of shielding effectiveness (SE) for high-frequency and transient electromagnetic fields were introduced by Klinkenbusch (2005). Analytical results were shown for closed as well as for non closed cylindrical shields. In the present work, the shielding performance of different shielding cabinets is investigated by means of numerical simulations and measurements inside a fully anechoic chamber and a GTEM-cell. For the GTEM-cell-measurements, a downscaled model of the shielding cabinet is used. For the simulations, the numerical tools CONCEPT II and COMSOL MULTIPHYSICS were available. The numerical results agree well with the measurements. They can be used to interpret the behaviour of the shielding effectiveness of enclosures as function of frequency. From the measurement of the electric and magnetic fields with and without the enclosure in place, the electric and magnetic shielding effectiveness as well as the transient shielding effectiveness of the enclosure are calculated. The transient SE of four different shielding cabinets is determined and discussed.
Subjects of discussion in radiated emission measurements above 1 GHz
Authors: Battermann S. , Garbe H.
Published: April 2010

Abstract. Some emission and susceptibility EMC standards already require measurements above 1 GHz or test site validations (IEC 2006, CISPR 2006). A simple assignment of the established measurement methods below 1 GHz to the frequency range above 1 GHz bears some risks. The ratio between the physical size of the equipment under test (EUT) and the wave-length rises with frequency. This increases the electrical size of the EUT. The directivity may become larger and the radiation pattern of the EUT is getting more complex which reduces the probability to detect the maximum emission with a simple planar cut scan. To analyse these effects in more detail this paper shows radiation characteristics of an exemplary EUT. The influence of a receiving antenna height scan and the angle increment of the turntable scan on the detection of the maximum of the electrical field strength will be discussed. As a result some ideas will be given to reduce the measurement time but keeping the reliability of the measurement results constant.
Power optimization of digital baseband WCDMA receiver components on algorithmic and architectural level
Authors: Schämann M. , Bücker M. , Hessel S. , Langmann U.
Published: April 2010

Abstract. High data rates combined with high mobility represent a challenge for the design of cellular devices. Advanced algorithms are required which result in higher complexity, more chip area and increased power consumption. However, this contrasts to the limited power supply of mobile devices. This presentation discusses the application of an HSDPA receiver which has been optimized regarding power consumption with the focus on the algorithmic and architectural level. On algorithmic level the Rake combiner, Prefilter-Rake equalizer and MMSE equalizer are compared regarding their BER performance. Both equalizer approaches provide a significant increase of performance for high data rates compared to the Rake combiner which is commonly used for lower data rates. For both equalizer approaches several adaptive algorithms are available which differ in complexity and convergence properties. To identify the algorithm which achieves the required performance with the lowest power consumption the algorithms have been investigated using SystemC models regarding their performance and arithmetic complexity. Additionally, for the Prefilter Rake equalizer the power estimations of a modified Griffith (LMS) and a Levinson (RLS) algorithm have been compared with the tool ORINOCO supplied by ChipVision. The accuracy of this tool has been verified with a scalable architecture of the UMTS channel estimation described both in SystemC and VHDL targeting a 130 nm CMOS standard cell library. An architecture combining all three approaches combined with an adaptive control unit is presented. The control unit monitors the current condition of the propagation channel and adjusts parameters for the receiver like filter size and oversampling ratio to minimize the power consumption while maintaining the required performance. The optimization strategies result in a reduction of the number of arithmetic operations up to 70% for single components which leads to an estimated power reduction of up to 40% while the BER performance is not affected. This work utilizes SystemC and ORINOCO for the first estimation of power consumption in an early step of the design flow. Thereby algorithms can be compared in different operating modes including the effects of control units. Here an algorithm having higher peak complexity and power consumption but providing more flexibility showed less consumption for normal operating modes compared to the algorithm which is optimized for peak performance.
Sievenpiper HIS and its influence on antenna correlation
Authors: Hampel S. K. , Schmitz O. , Rolfes I.
Published: April 2010

Abstract. \\label{sec:abstract} This paper deals with the influence of artificial magnetic conductors (AMC), so-called Sievenpiper High Impedance Surfaces (HIS), on the MIMO and Diversity performance of a planar linear-polarized 2×2 dipole array in the ISM-band at 2.45 GHz. The characteristic performance criteria such as envelope correlation coefficient, spectral efficiency, Mean Effective Gain (MEG) and Diversity gain of a coupled 2×2 dipole array are investigated. By means of full-wave electromagnetic analysis as well as Monte-Carlo simulations applying statistical channel models the characteristic antenna pattern just as the MIMO and Diversity analysis is performed, respectively. The obtained results show that the application of Sievenpiper High Impedance Surfaces to planar antenna arrays enables good MIMO and Diversity performance compared to ideal configurations in free-space while offering the design of low profile antennas with simultaneously enhanced characteristics.
Bistatic extension for coherent MMW-ISAR-Imaging of objects and humans
Authors: Bertl S. , Dallinger A. , Detlefsen J.
Published: April 2010

Abstract. We present a bistatic extension of a broadband monostatic FMCW Radar working in the Millimetre-Wave (MMW) region and its bistatic imaging properties used for imaging purposes. Due to the different perspective of a bistatic setup compared to a monostatic one, additional information can be obtained. A wide bandwidth of approx. 10 GHz is used for the task of high resolution imaging as it could be used for the detection of threats at a person's body in security-sensitive environments. Since MMWs propagate easily through common clothing, it is feasible to image objects like concealed weapons worn under the clothing. MMW-Imaging of humans is one possibility to enhance the capabilities of nowadays security checkpoints, e.g. at airports.
Transformation of passive electrical networks with distributed PWL-sources using a Model Order Reduction
Authors: Ludwig S. , Mathis W.
Published: April 2010

Abstract. In modeling of distributed systems with distributed sources large networks with RLC-elements and independent sources arise. This high complexity leads to a high effort in simulations. Therefore model reduction can be used to reduce these networks, preserving the behavior at the observed nodes in the networks. For the reduction of networks with a large number of independent sources only a weak reduction is enabled with standard model reduction techniques. In this paper an efficient reduction of networks with a large number of sources with piece-wise-linear waveforms is presented, using the decomposition of piece-wise-linear functions. With the proposed method a higher reduction of the network and/or a higher accuracy can be achieved with model reduction. The validity and efficiency of the proposed method is shown by reducing a RCI-Grid model.
Analyse unterschiedlicher Modellierungsvarianten des "Direct Power Injection" Verfahrens für die EMV Charakterisierung integrierter Schaltungen
Authors: Stürmer U. , Ritzmann S. , Jovic O. , Wilkening W.
Published: April 2010

Abstract. Dieser Beitrag analysiert zwei Ansätze zur Modellierung eines Teststandes zur Charakterisierung von integrierten Schaltungen mittels Direct Power Injection (DPI) auf einem Wafer. Die erste Variante ist zur Analyse bereits vorliegender integrierter Schaltungen nutzbar. Sie benötigt gemessene S-Parameterdaten, mit denen die an einem realen Messobjekt anliegenden Störspannungen frequenzabhängig bestimmt werden können. Die zweite Variante ist bereits anwendbar, bevor Silizium gefertigt worden ist. Sie modelliert einen Netzwerkanalysatorkanal der aus einer Signalquelle, einem Leistungsmesser und einem Verstärker mit nachgeschaltetem Richtkoppler und Entkoppelnetzwerken besteht. Zunächst werden die oben genannten verschiedenen Varianten der DPI-Streckenmodellierung dargestellt. Sie werden miteinander und anhand von Messdaten einer einfachen Teststruktur verglichen. Die Teststruktur besteht aus einem MOS-Transistor mit Arbeitswiderstand. Der Beitrag diskutiert Vor- und Nachteile der Varianten einschließlich Modellierungsaufwand und Simulationsgeschwindigkeit.
Modellierung und Simulation des Substrat-Rauschens in integrierten RF CMOS-Schaltungen
Authors: Lin L. , Xiong J. , Mathis W.
Published: April 2010

Abstract. Im integrierten CMOS-Schaltungsentwurf kann das Substrat-Rauschen, das vom digitalen Teil entsteht, die Funktionalität des analogen Teils stark beeinflussen. Es wird daher immer wichtiger, das Substrat als ein Medium der Rauschen-Propagation genau zu modellieren. Im vorliegenden Artikel wird ein auf der Finite Elemente Methode (FEM) und Modellordnungsreduktion (MOR) basiertes Modellierungsverfahren zur Admittanzen-Extraktion im Halbleitersubstrat vorgestellt. Nach der Diskretisierung mit FEM wird das Substrat im Allgemeinen als ein resistives/kapazitives Netz angesehen. Durch Bestimmung der Admittanz-Matrix und MOR ist es möglich ein äquivalentes Dreipol-Modell zwischen digitalem und analogem Teil über das Substrat zu bilden. Das Ergebnis der Modellierung wird dargestellt und mit numerischer Simulation des Substrat-Rauschens verglichen. Die Modellierung ermöglicht es, die Einflüsse des Substrat-Rauschens im Schaltungsentwurf zu berücksichtigen und so bestehende CMOS-Schaltungsarchitekturen zu optimieren.
Nichtlineare Analyse von LC-TANK VCOs unter Berücksichtigung parasitärer Substrateffekte
Authors: Przytarski J. , Bremer J.-K. , Mathis W.
Published: April 2010

Abstract. In dieser Arbeit wird ein Konzept vorgestellt, die Schaltungsarchitektur des LC-Tank-VCOs im höherdimensionalen Zustandsraum zu modellieren. Dabei wurde die VCO-Schaltung auf dominante nichtlineare und asymmetrische Effekte näher untersucht. Das entwickelte Modell bildet die Grundlage für nachfolgende parameterabhängige Analysen der Oszillatorschaltung mittels der Andronov-Hopf Bifurkationsanalyse. Zu diesem Zweck wurde ein höherdimensionales Modell entwickelt, welches für die Bifurkationsanalyse auf ein System 2. Ordnung reduziert werden muss. Als mathematisches Hilfsmittel zur Ordnungsreduktion des Systems wird das Verfahren der Zentrumsmannigfaltigkeit verwendet. Das Differentialgleichungssystem wird sehr schaltungsnah aufgestellt, daraus resultiert der Vorteil einer genaueren Repräsentation des physikalischen Verhaltens der Schaltung. Ziel ist es möglichst viele Effekte die sich auf das Verhalten des VCOs auswirken können, mit zu berücksichtigen.
Modellierung von Quanteneffekten in einem ladungsbasierten MOS-Transistor-Modell zur Simulation von nanoskalierten CMOS-Analogschaltungen
Authors: Stegemann S. , Xiong J. , Mathis W.
Published: April 2010

Abstract. Aufgrund der fortschreitenden Miniaturisierung der Bauelemente in CMOS-Schaltungen und den dadurch erreichten Strukturgrößen nehmen quantenmechanische Effekte zunehmenden Einfluss auf die Funktion von Transistoren und damit auf die gesamte Schaltung. Unter Einbeziehung der Energiequantisierung an der Si/SiO2-Grenzfläche wird untersucht, wie sich durch eine Modifikation der Beschreibung des Oberflächenpotenzials die Inversionsladung quantenmechanisch formulieren lässt. Im Hinblick auf den Entwurf und die Simulation von CMOS-Analogschaltungen wird dazu ein ladungsbasiertes MOS-Transistor-Modell zugrunde gelegt. Die sich daraus ergebenden Veränderungen für die Kapazitäten und die Inversionsladung werden dabei für die Modellierung des quasiballistischen Drain-Source-Stromes verwendet. Dazu wird innerhalb dieses Modells ein Streufaktor berechnet, mit dem nanoskalierte MOS-Transistoren mit einer Kanallänge von unter 20 nm simuliert werden können. Ausgehend von Parametern eines CMOS-Prozesses werden mit MATLAB die Einflüsse der quantenmechanischen Effekte bei der Skalierung des Transistors analysiert.
Impact of negative and positive bias temperature stress on 6T-SRAM cells
Authors: Drapatz S. , Georgakos G. , Schmitt-Landsiedel D.
Published: April 2010

Abstract. With introduction of high-k gate oxide materials, the degradation effect Positive Bias Temperature Instability (PBTI) is starting to play an important role. Together with the still effective Negative Bias Temperature Instability (NBTI) it has significant influence on the 6T SRAM memory cell. We present simulations of both effects, first isolated, then combined in SRAM operation. During long hold of one data, both effects add up to a worst case impact. This leads to an asymmetric cell, which, in a directly following read cycle, combined with the generally unavoidable production variations, maximizes the risk of destructive reading. In future SRAM designs, it will be important to consider this combination of effects to avoid an undesired write event.
Circuit design with Independent Double Gate Transistors
Authors: Weis M. , Emling R. , Schmitt-Landsiedel D.
Published: April 2010

Abstract. Circuits with transistors using independently controlled gates have been proposed to reduce the number of transistors and to increase the logic density per area. This paper introduces a novel Vertical Slit Field Effect Transistor with unique independent double gate properties to demonstrate the possible advantages for independent double gate circuits. A new adder circuit is proposed, where the power could be reduced by one fifth and the area by on third compared to a tied gate configuration.
High-voltage (100 V) ChipfilmTM single-crystal silicon LDMOS transistor for integrated driver circuits in flexible displays
Authors: Asif A. , Richter H. , Burghartz J. N.
Published: April 2010

Abstract. System-in-Foil (SiF) is an emerging field of large-area polymer electronics that employs new materials such as conductive polymers and electrophoretic micro-capsules (E-Ink) along with ultra-thin and thus flexible chips. In flexible displays, the integration of gate and source drivers onto the flexible part increases the yield and enhances the reliability of the system. In this work we propose a high-voltage ChipfilmTM lateral diffused MOS transistor (LDMOS) structure on ultra-thin single-crystalline silicon chips. The fabrication process is compatible with CMOS standard processing. This LDMOS structure proves to be well suited for providing adequately large switching voltages in spite of the thin (<10 μm) substrate. A breakdown voltage of more than 100 volts with drain-to-source saturation current Ids(sat)≈85 μA/μm for N-LDMOS and Ids(sat)≈20 μA/μm for P-LDMOS is predicted through process and device simulations.
Improving MIMO-OFDM decision-directed channel estimation by utilizing error-correcting codes
Authors: Beinschob P. , Lieberei M. , Zölzer U.
Published: April 2010

Abstract. In this paper a decision-directed Multiple-Input Multiple-Output (MIMO) channel tracking algorithm is enhanced to raise the channel estimate accuracy. While DDCE is prone to error propagation the enhancement employs channel decoding in the tracking process. Therefore, a quantized block of symbols is checked on consistency via the channel decoder, possibly corrected and then used. This yields a more robust tracking of the channel in terms of bit error rate and improves the channel estimate under certain conditions. Equalization is performed to prove the feasibility of the obtained channel estimate. Therefore a combined signal consisting of data and pilot symbols is sent. Adaptive filters are applied to exploit correlations in time, frequency and spatial domain. By using good error-correcting coding schemes like Turbo Codes or Low Density Parity Check (LDPC) codes, adequate channel estimates can be acquired even at low signal to noise ratios (SNR). The proposed algorithm among two others is applied for channel estimation and equalization and results are compared.
Somewhere over the rainbow – advantages and pitfalls of colourful visualizations in geosciences
Authors: Spekat A. , Kreienkamp F.
Published: April 2010

Abstract. Computer-generated visualizations of geoscientific data, such as those from climate models are in high demand for a wide variety of usages; these include, among others, scientific publications, reports and graphical aides for the general public's improved understanding of complex developments. The paper will focus on the effects of colours in two-dimensional displays. Practical examples are given from which it becomes clear that considerable confusion or even damage can arise from an uninformed use of colour mapping and if results become, e.g., published in an unchecked manner by the media.
Sensitivity experiments of a severe rainfall event in north-western Italy: 17 August 2006
Authors: Milelli M. , Oberto E. , Parodi A.
Published: April 2010

Abstract. This study is embedded into a wider project named "Tackle deficiencies in Quantitative Precipitation Forecast (QPF)'' in the framework of the COSMO (COnsortium for Small-scale MOdelling) community. In fact QPF is an important purpose of a numerical weather prediction model, for forecasters and customers. Unfortunately, precipitation is also a very difficult parameter to forecast quantitatively. This priority project aims at looking into the COSMO Model deficiencies concerning QPF by running different numerical simulations of various events not correctly predicted by the model. In particular, this work refers to a severe event (moist convection) happened in Piemonte region during summer 2006. On one side the results suggest that details in orography representation have a strong influence on accuracy of QPF. On the other side COSMO Model exhibits a poor sensitivity on changes in numerical and physical settings when measured in terms of QPF improvements. The conclusions, although not too general, give some hint towards the behaviour of the COSMO Model in a typical convective situation.
Mesoscale heat waves induced by orography
Authors: Gladich I. , Gallai I. , Giaiotti D. B. , Mordacchini Gp. , Palazzo A. , Stel F.
Published: April 2010

Abstract. This work is devoted to the analysis of an unusual and sudden thermal fluctuation that interested portions of Friuli Venezia Giulia (Italy) during the night of 27 July 1983. The whole 1983 summer was extremely warm in Europe and in particular on the Italian peninsula, from the Alps down to Sicily. Nevertheless, the day of 27 July 1983 in Friuli Venezia Giulia deserves special attention because the observed maximum temperatures did not occur during day-time but during night-time (from 23:00 up to 24:00 LT, 21:00–22:00 UTC). Peaks of 34.8°C and values of relative humidity of the order of 28% were registered by the official network of weather stations. This event interested mainly the central-eastern part of the plain of Friuli Venezia Giulia, a few kilometers far from the Slovenian border and relieves. The thermal anomalies lasted up to an hour, then temperatures decreased toward values more usual for the climate of the month. The study of this event is carried out with the aid of the AR-WRF numerical atmospheric model, initialized through the ECMWF analysis. The numerical simulations highlight the important role played by orography, jointly with the peculiar thermal structure of the atmosphere, for the enhancing of the internal wave pattern over that area. According to the sensitivity studies realized, the amplification of the internal wave pattern might represent a possible explanation for that meteorological enigma.
Analysis of a low ozone episode over Extremadura (Spain) in January 2006 and its influence on UV radiation
Authors: Antón M. , Cancillo M. L. , Serrano A. , García J. A. , Acero F. J.
Published: April 2010

Abstract. The main objectives of this work are to analyze, firstly, the detail of the causes of a low ozone event which occurred in January 2006 and, secondly, the related effects of this anomalous episode on ultraviolet (UV) radiation measured at three locations in Extremadura (South-Western Spain). On 19 January 2006, the OMI total ozone column (TOC) was 16–20% below the January mean value of TOMS/NASA TOC (period 1996–2005). The back trajectories analysis with the HYSplit model indicates that the notable decrease of TOC could be attributed to a fast rise of the isentropic trajectories height. Concomitantly, UV erythemal radiation greatly increases (between 23% and 37%) on 19 January 2006 respect to UV erythemal radiation measured on 19 January 2005. This notable increase in winter UV solar radiation may involve harmful effects for organisms adapted to receive less radiation during that season (e.g. early developmental stages of terrestrial plants and phytoplankton).
The impact of biogenic VOC emissions on photochemical ozone formation during a high ozone pollution episode in the Iberian Peninsula in the 2003 summer season
Authors: Castell N. , Stein A. F. , Salvador R. , Mantilla E. , Millán M.
Published: April 2010

Abstract. Throughout Europe the summer of 2003 was exceptionally warm, especially July and August. The European Environment Agency (EEA) reported several ozone episodes, mainly in the first half of August. These episodes were exceptionally long-lasting, spatially extensive, and associated to high temperatures. In this paper, the 10$ndash;15 August 2003 ozone pollution event has been analyzed using meteorological and regional air quality modelling. During this period the threshold values of the European Directive 2002/3/EC were exceeded in various areas of the Iberian Peninsula. The aim of this paper is to computationally understand and quantify the influence of biogenic volatile organic compound (BVOC) emissions in the formation of tropospheric ozone during this high ozone episode. Being able to differentiate how much ozone comes from biogenic emissions alone and how much comes from the interaction between anthropogenic and biogenic emissions would be helpful to develop a feasible and effective ozone control strategy. The impact on ozone formation was also studied in combination with various anthropogenic emission reduction strategies, i.e., when anthropogenic VOC emissions and/or NOx emissions are reduced. The results show a great dependency of the BVOC contribution to ozone formation on the antropoghenic reduction scenario. In rural areas, the impact due to a NOx and/or VOC reduction does not change the BVOC impact. Nevertheless, within big cities or industrial zones, a NOx reduction results in a decrease of the biogenic impact in ozone levels that can reach 85 μg/m3, whereas an Anthropogenic Volatile Organic Compound (AVOC) reduction results in a decrease of the BVOC contribution on ozone formation that varies from 0 to 30 μg/m3 with respect to the contribution at the same points in the 2003 base scenario. On the other hand, downwind of the big cities, a decrease in NOx produces a minor contribution of biogenic emissions and a decrease in AVOCs results in greater contributions of BVOCs to the formation of ozone.
Reference crop evapotranspiration estimate using high-resolution meteorological network's data
Authors: Lussana C. , Uboldi F.
Published: April 2010

Abstract. Water management authorities need detailed information about each component of the hydrological balance. This document presents a method to estimate the evapotranspiration rate, initialized in order to obtain the reference crop evapotranspiration rate (ET0). By using an Optimal Interpolation (OI) scheme, the hourly observations of several meteorological variables, measured by a high-resolution local meteorological network, are interpolated over a regular grid. The analysed meteorological fields, containing detailed meteorological information, enter a model for turbulent heat fluxes estimation based on Monin-Obukhov surface layer similarity theory. The obtained ET0 fields are then post-processed and disseminated to the users.
Possible adaptation measures of agriculture sector in the Nile Delta to climate change impacts
Authors: Attaher S. M. , Medany M. A. , Abou-Hadid A. F.
Published: April 2010

Abstract. The overall agricultural system in the Nile Delta region is considered as one of the highest intensive and complicated agriculture systems in the world. According to the recent studies, the Nile Delta region is one of the highly vulnerable regions in the world to climate change. Sea level rise, soil and water degradation, undiversified crop-pattern, yield reduction, pests and disease severity, and irrigation and drainage management were the main key factors that increased vulnerability of the agriculture sector in that region. The main objective of this study is to conduct a community-based multi-criteria adaptation assessment in the Nile Delta using a preset questionnaire. A list of possible adaptation measures for agriculture sector was evaluated. The results indicated that the Nile Delta growers have strong perceptions to act positively to reduce the impacts of climate change. They reflected the need to improve the their adaptive capacity based on clear scientific message with adequate governmental support to coop with the negative impacts of climate change.
Adaptation of vulnerable regional agricultural systems in Europe to climate change – results from the ADAGIO project
Authors: Eitzinger J. , Kubu G. , Alexandrov V. , Utset A. , Mihailovic D. T. , Lalic B. , Trnka M. , Zalud Z. , Semeradova D. , Ventrella D. , Anastasiou D. P. , Medany M. , Altaher S. , Olejnik J. , Lesny J. , Nemeshko N. , Nikolaev M. , Simota C. , Cojocaru G.
Published: April 2010

Abstract. During 2007-2009 the ADAGIO project (http://www.adagio-eu.org) is carried out to evaluate regional adaptation options in agriculture in most vulnerable European regions (mediterranean, central and eastern European regions). In this context a bottom-up approach is used beside the top-down approach of using scientific studies, involving regional experts and farmers in the evaluation of potential regional vulnerabilities and adaptation options. Preliminary results of the regional studies and gathered feedback from experts and farmers show in general that (increasing) drought and heat are the main factors having impact on agricultural vulnerability not only in the Mediterranean region, but also in the Central and southern Eastern European regions. Another important aspect is that the increasing risk of pest and diseases may play a more important role for agricultural vulnerability than assumed before, however, till now this field is only rarely investigated in Europe. Although dominating risks such as increasing drought and heat are similar in most regions, the vulnerabilities in the different regions are very much influenced by characteristics of the dominating agroecosystems and prevailing socio-economic conditions. This will be even be more significant for potential adaptation measures at the different levels, which have to reflect the regional conditions.
Biodiversity and climate change in relation to the Natura 2000 network
Authors: Harley M. , de Soye Y. , Dickson B. , Tucker G. , Keder G.
Published: April 2010

Abstract. This project will provide the European Commission (EC) with an overview of the likely impacts of climate change on biodiversity in the European Union (EU), particularly within the Natura 2000 (N2K) network of protected areas, and indications of how the design and implementation of current policy might need to be adapted to ensure that the EU delivers its commitment to halt biodiversity loss by 2010 and beyond. The study will identify those species and associated habitats that are likely to be most vulnerable to climate change and the steps required to protect the integrity of the network from negative effects. The study will also assess the impacts of large-scale renewable energy schemes (wind parks, hydroelectric schemes and tidal barrages) on biodiversity and produce guidelines on the sorts of measures that might be used to maintain and protect N2K sites.
Multi-scale atmospheric environment modelling for urban areas
Authors: Baklanov A. A. , Nuterman R. B.
Published: April 2010

Abstract. Modern supercomputers allow realising multi-scale systems for assessment and forecasting of urban meteorology, air pollution and emergency preparedness and considering nesting with obstacle-resolved models. A multi-scale modelling system with downscaling from regional to city-scale with the Environment – HIgh Resolution Limited Area Model (Enviro-HIRLAM) and to micro-scale with the obstacle-resolved Micro-scale Model for Urban Environment (M2UE) is suggested and demonstrated. The M2UE validation results versus the Mock Urban Setting Trial (MUST) experiment indicate satisfactory quality of the model. Necessary conditions for the choice of nested models, building descriptions, areas and resolutions of nested models are analysed. Two-way nesting (up- and down-scaling), when scale effects both directions (from the meso-scale on the micro-scale and from the micro-scale on the meso-scale), is also discussed.
On daily interpolation of precipitation backed with secondary information
Authors: Krähenmann S. , Ahrens B.
Published: April 2010

Abstract. This paper investigates the potential impact of secondary information on rainfall mapping applying Ordinary Kriging. Secondary information tested is a natural area indicator, which is a combination of topographic features and weather conditions. Cross validation shows that secondary information only marginally improves the final mapping, indicating that a one-day accumulation time is possibly too short.
A field-based method for simultaneous measurements of the δ18O and δ13C of soil CO2 efflux
Authors: Mortazavi B. , Prater J. L. , Chanton J. P.
Published: April 2010

Abstract. Three approaches for determining the stable isotopic composition (δ13C and δ18O) of soil CO efflux were compared. A new technique employed mini-towers, constructed of open-topped piping, that were placed on the soil surface to collect soil-emitted CO2. Samples were collected along a vertical gradient and analyzed for CO2 concentration and isotopic composition. These data were then used to produce Keeling plots to determine the δ18O and δ13C of CO2 emitted from the soil. These results were then compared to the δ18O and δ13C of soil-respired CO2 measured with two other techniques: (1) flux chambers and (2) estimation from the application of the diffusional fractionation factor to measured values of below ground soil CO2 and to CO2 in equilibrium with soil water δ18O. Mini-tower δ18O Keeling plots were linear and highly significant (0.81< r 2 > 0.96), in contrast to chamber δ18O Keeling plots, which showed significant curvature, necessitating the use of a mass balance to calculate the δ18O of respired CO2. In the chambers, the values determined for the δ18O of soil respired CO2 approached the value of CO2 in equilibrium with surficial soil water, and the results were significantly δ18O enriched relative to the mini-tower results and the δ18O of soil CO2 efflux determined from soil CO2. There were close agreements between the three methods for the determination of the δ13C of soil efflux CO2. Results suggest that the mini-towers can be effectively used in the field for determining the δ18O and the δ13C of soil-respired CO2.
Modeling the nitrogen fluxes in the Black Sea using a 3D coupledhydrodynamical-biogeochemical model: transport versus biogeochemicalprocesses, exchanges across the shelf break and comparison of the shelf anddeep sea ecodynamics
Authors: Grégoire M. , Beckers J. M.
Published: April 2010

Abstract. A 6-compartment biogeochemical model of nitrogen cycling and plankton productivity has been coupled with a 3D general circulation model in an enclosed environment (the Black Sea) so as to quantify and compare, on a seasonal and annual scale, the typical internal biogeochemical functioning of the shelf and of the deep sea as well as to estimate the nitrogen and water exchanges at the shelf break. Model results indicate that the annual nitrogen net export to the deep sea roughly corresponds to the annual load of nitrogen discharged by the rivers on the shelf. The model estimated vertically integrated gross annual primary production is 130gCm-2yr-1 for the whole basin, 220gCm-2yr-1 for the shelf and 40gCm-2yr-1 for the central basin. In agreement with sediment trap observations, model results indicate a rapid and efficient recycling of particulate organic matter in the sub-oxic portion of the water column (60-80m) of the open sea. More than 95% of the PON produced in the euphotic layer is recycled in the upper 100m of the water column, 87% in the upper 80 m and 67% in the euphotic layer. The model estimates the annual export of POC towards the anoxic layer to 4 1010molyr-1. This POC is definitely lost for the system and represents 2% of the annual primary production of the open sea.
Link or sink: a modelling interpretation of the open Baltic biogeochemistry
Authors: Vichi M. , Ruardij P. , Baretta J. W.
Published: April 2010

Abstract. A 1-D model system, consisting of the 1-D version of the Princeton Ocean Model (POM) coupled with the European Regional Seas Ecosystem Model (ERSEM) has been applied to a sub-basin of the Baltic Proper, the Bornholm basin. The model has been forced with 3h meteorological data for the period 1979-1990, producing a 12-year hindcast validated with datasets from the Baltic Environmental Database for the same period. The model results demonstrate the model to hindcast the time-evolution of the physical structure very well, confirming the view of the open Baltic water column as a three layer system of surface, intermediate and bottom waters. Comparative analyses of modelled hydrochemical components with respect to the independent data have shown that the long-term system behaviour of the model is within the observed ranges. Also primary production processes, deduced from oxygen (over)saturation are hindcast correctly over the entire period and the annual net primary production is within the observed range. The largest mismatch with observations is found in simulating the biogeochemistry of the Baltic intermediate waters. Modifications in the structure of the model (addition of fast-sinking detritus and polysaccharide dynamics) have shown that the nutrient dynamics are linked to the quality and dimensions of the organic matter produced in the euphotic zone, highlighting the importance of the residence time of the organic matter within the microbial foodweb in the intermediate waters. Experiments with different scenarios of riverine nutrient loads, assessed in the limits of a 1-D setup, have shown that the external input of organic matter makes the open Baltic model more heterotrophic. The characteristics of the inputs also drive the dynamics of nitrogen in the bottom layers leading either to nitrate accumulation (when the external sources are inorganic), or to coupled nitrification-denitrification (under strong organic inputs). The model indicates the permanent stratification to be the main feature of the system as regulator of carbon and nutrient budgets. The model predicts that most of the carbon produced in the euphotic zone is also consumed in the water column and this enhances the importance of heterotrophic benthic processes as final closure of carbon and nutrient cycles in the open Baltic.
Global uptake of carbonyl sulfide (COS) by terrestrial vegetation: Estimates corrected by deposition velocities normalized to the uptake of carbon dioxide (CO2)
Authors: Sandoval-Soto L. , Stanimirov M. , von Hobe M. , Schmitt V. , Valdes J. , Wild A. , Kesselmeier J.
Published: April 2010

Abstract. COS uptake by trees, as observed under dark/light changes and under application of the plant hormone abscisic acid, exhibited a strong correlation with the CO2 assimilation rate and the stomatal conductance. As the uptake of COS occurred exclusively through the stomata we compared experimentally derived and re-evaluated deposition velocities (Vd; related to stomatal conductance) for COS and CO2. We show that Vd of COS is generally significantly larger than that of CO2. We therefore introduced this attribute into a new global estimate of COS fluxes into vegetation. The new global estimate of the COS uptake based on available net primary productivity data (NPP) ranges between 0.69-1.40 Tga-1. However, as a COS molecule is irreversibly split in contrast to CO2 which is released again by respiration processes, we took into account the Gross Primary Productivity (GPP) representing the true CO2 leaf flux the COS uptake has to be related to. Such a GPP based deposition estimate ranged between 1.4-–2.8 Tga-1 (0.73-1.50 TgSa-1). We believe that in order to obtain accurate global COS sink estimates such a GPP-based estimate corrected by the different deposition velocities of COS and CO2 must be taken into account.
Non-invasive diagnostics in fossils - Magnetic Resonance Imaging of pathological belemnites
Authors: Mietchen D. , Keupp H. , Manz B. , Volke F.
Published: April 2010

Abstract. For more than a decade, Magnetic Resonance Imaging (MRI) has been routinely employed in clinical diagnostics because it allows non-invasive studies of anatomical structures and physiological processes in vivo and to differentiate between healthy and pathological states, particularly of soft tissue. Here, we demonstrate that MRI can likewise be applied to fossilized biological samples and help in elucidating paleopathological and paleoecological questions: Five anomalous guards of Jurassic and Cretaceous belemnites are presented along with putative paleopathological diagnoses directly derived from 3D MR images with microscopic resolution. Syn vivo deformities of both the mineralized internal rostrum and the surrounding former soft tissue can be traced back in part to traumatic events of predator-prey-interactions, and partly to parasitism. Besides, evidence is presented that the frequently observed anomalous apical collar might be indicative of an inflammatory disease. These findings highlight the potential of Magnetic Resonance techniques for further paleontological applications.
Solubilization of particles in sediment traps: revising the stoichiometry of mixed layer export
Authors: Antia A. N.
Published: April 2010

Abstract. Sinking particles, once caught in sediment trap jars, release dissolved elements into the surrounding medium through leaching from their pore fluids, chemical dissolution and the activity of free exoenzymes. This results in an increase in dissolved elements in the trap jar supernatant. Elemental fluxes as traditionally measured by sediment traps underestimate total export when this particle-associated dissolved flux is not considered. The errors introduced are variable and alter both the absolute levels of flux as well as the stoichiometry of export. These errors have been quantified and corrections applied for samples from sediment traps in the North Atlantic based on measurements of excess dissolved carbon, nitrogen, phosphorus, silica and calcium in the supernatant of the collection cups. At the base of the winter mixed layer, on average 90±6% of phosphorus fluxes are found as excess phosphate whereas for carbon and nitrogen dissolved concentrations account for 30 (±8)% and 47(±11)% of total fluxes respectively. Excess dissolved silica is on average 61 (±17)% of total biogenic silica flux. Little (<10%) of calcium is solubilized. The proportion of dissolved to total flux decreases with trap deployment depth. Calculations of the C:N:P ratios for particles only are well above the Redfield ratios of 106:16:1 (Redfield et al., 1963), although the mid-water dissolved N:P and N:Si values as well as the C:N:P ratios of remineralisation along isopycnals conform to the Redfield ratios at this site. Accounting for dissolved fluxes of all these elements brings the stoichiometry of export in agreement with the Redfield Ratio and with other geochemical estimates of winter mixed layer export. A factor of 3 to 4 higher ratios of organic: inorganic carbon export also implies that the net atmospheric CO2 sequestration by the biological pump is about 50% higher at this site when the dissolved elemental fluxes are considered. Solubilization is thus a process that should be accounted for in protocols used to measure vertical fluxes with sediment traps.
Seasonal cycling of phosphorus in the Southern Bight of the North Sea
Authors: van der Zee C. , Chou L.
Published: April 2010

Abstract. We have investigated the seasonal cycle of nutrients, chlorophyll a, dissolved organic nitrogen (DON), and dissolved and particulate organic carbon (DOC and POC) for 10 stations in the Belgian coastal zone. Special attention was given to phosphorus speciation, i.e. dissolved inorganic and organic phosphorus (DIP and DOP) and particulate inorganic and organic phosphorus (PIP and POP). Spatial and temporal trends of the inorganic nutrients and the organic species are discussed. The Belgian part of the southern North Sea is strongly influenced by the river plumes of the Rhine, Meuse and Scheldt resulting in northeast-southwest salinity gradient. Extrapolation of winter nutrient and DOC concentrations versus salinity plots yielded zero-salinity values typical of the river Scheldt. The polyphosphate concentration did not show any temporal trend, whereas both the phosphate and the DOP concentrations exhibited distinct seasonal variations. Silica or phosphorus was the potential limiting nutrient for phytoplankton growth based on elemental ratios.
Factors influencing the dissolved iron input by river water to the open ocean
Authors: Krachler R. , Jirsa F. , Ayromlou S.
Published: April 2010

Abstract. The influence of natural metal chelators on the bio-available iron input to the ocean by river water was studied. Ferrous and ferric ions present as suspended colloidal particles maintaining the semblance of a dissolved load are coagulated and settled as their freshwater carrier is mixed with seawater at the continental boundary. However, we might argue that different iron-binding colloids become sequentially destabilized in meeting progressively increasing salinities. By use of a 59Fe tracer method, the partitioning of the iron load from the suspended and dissolved mobile fraction to storage in the sediments was measured with high accuracy in mixtures of natural river water with artificial sea water. The results show a characteristic sequence of sedimentation. Various colloids of different stability are removed from a water of increasing salinity, such as it is the case in the transition from a river water to the open sea. However, the iron transport capacities of the investigated river waters differed greatly. A mountainous river in the Austrian Alps would add only about 5% of its dissolved Fe load, that is about 2.0 µg L-1 Fe, to coastal waters. A small tributary draining a sphagnum peat-bog, which acts as a source of refractory low-molecular-weight fulvic acids to the river water, would add approximately 20% of its original Fe load, that is up to 480 µg L-1 Fe to the ocean's bio-available iron pool. This points to a natural mechanism of ocean iron fertilization by terrigenous fulvic-iron complexes originating from weathering processes occurring in the soils upstream.
Inventories of N2O and NO emissions from European forest soils
Authors: Kesik M. , Ambus P. , Baritz R. , Brüggemann N. , Butterbach-Bahl K. , Damm M. , Duyzer J. , Horváth L. , Kiese R. , Kitzler B. , Leip A. , Li C. , Pihlatie M. , Pilegaard K. , Seufert S. , Simpson D. , Skiba U. , Smiatek G. , Vesala T. , Zechmeister-Boltenstern S.
Published: April 2010

Abstract. Forest soils are a significant source for the primary and secondary greenhouse gases N2O and NO. However, current estimates are still uncertain due to the still limited number of field measurements and the herein observed pronounced variability of N trace gas fluxes in space and time, which are due to the variation of environmental factors such as soil and vegetation properties or meteorological conditions. To overcome these problems we further developed a process-oriented model, the PnET-N-DNDC model, which simulates the N trace gas exchange on the basis of the processes involved in production, consumption and emission of N trace gases. This model was validated against field observations of N trace gas fluxes from 19 sites obtained within the EU project NOFRETETE, and shown to perform well for N2O (r2=0.68, slope=0.76) and NO (r2=0.78, slope=0.73). For the calculation of a European-wide emission inventory we linked the model to a detailed, regionally and temporally resolved database, comprising climatic properties (daily resolution), and soil parameters, and information on forest areas and types for the years 1990, 1995 and 2000. Our calculations show that N trace gas fluxes from forest soils may vary substantial from year to year and that distinct regional patterns can be observed. Our central estimate of NO emissions from forest soils in the EU amounts to 98.4, 84.9 and 99.2 kt N yr−1, using meteorology from 1990, 1995 and year 2000, respectively. This is <1.0% of pyrogenic NOx emissions. For N2O emissions the central estimates were 86.8, 77.6 and 81.6 kt N yr−1, respectively, which is approx. 14.5% of the source strength coming from agricultural soils. An extensive sensitivity analysis was conducted which showed a range in emissions from 44.4 to 254.0 kt N yr−1 for NO and 50.7 to 96.9 kt N yr−1 for N2O, for year 2000 meteorology. The results show that process-oriented models coupled to a GIS are useful tools for the calculation of regional, national, or global inventories of biogenic N trace gas emissions from soils. This work represents the most comprehensive effort to date to simulate NO and N2O emissions from European forest soils.