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  • 1
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    Copernicus
    Publication Date: 2018-03-05
    Description: An evaluation of the potential of Sentinel 1 for improving flash flood predictions via soil moisture–data assimilation Luca Cenci, Luca Pulvirenti, Giorgio Boni, Marco Chini, Patrick Matgen, Simone Gabellani, Giuseppe Squicciarino, and Nazzareno Pierdicca Adv. Geosci., 44, 89-100, https://doi.org/10.5194/adgeo-44-89-2017, 2017 This research aims at improving hydrological modelling skills of flash flood prediction by exploiting earth observation data. To this aim, high spatial/moderate temporal resolution soil moisture maps, derived from Sentinel 1 acquisitions, were used in a data assimilation framework. Findings revealed the potential of Sentinel 1-based soil moisture data assimilation for flash flood risk reduction and improved our understanding of the capabilities of the aforementioned satellite-derived product.
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    Topics: Geosciences
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  • 2
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    Copernicus
    Publication Date: 2018-03-05
    Description: Design of a dual linear polarization antenna using split ring resonators at X-band Sadiq Ahmed and Madhukar Chandra Adv. Radio Sci., 15, 259-267, https://doi.org/10.5194/ars-15-259-2017, 2017 In this paper, a novel approach (using metamaterials) is used to enhance the XPD for a dual linear polarization patch antenna at the frequency of 10 GHz. This improvement is obtained by placing two S-RRs close to the microstrip patch antenna, placing a SRR between two microstrip feed lines, and etching two pairs of CSRRs in the ground plane. An improvement in the XPD by 8.8 dB as compared to the conventional dual linear polarization antenna is noticed.
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  • 3
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    Copernicus
    Publication Date: 2018-03-05
    Description: Design of a carrier-depletion Mach-Zehnder modulator in 250 nm silicon-on-insulator technology María Félix Rosa, Lotte Rathgeber, Raik Elster, Niklas Hoppe, Thomas Föhn, Martin Schmidt, Wolfgang Vogel, and Manfred Berroth Adv. Radio Sci., 15, 269-281, https://doi.org/10.5194/ars-15-269-2017, 2017 We present the design of an optical modulator for amplitude modulation in a special silicon-on-insulator technology with 250 nm silicon layer thickness. The design of the modulator is optimized by simulating different parameters like dimension of the structure and doping of the silicon to improve the performance of the device. In addition, a prototype is fabricated and successfully measured to demonstrate the functionality of the technology.
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  • 4
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    Copernicus
    Publication Date: 2018-03-05
    Description: Experimentelles FMCW-Radar zur hochfrequenten Charakterisierung von Windenergieanlagen Karsten Schubert, Jens Werner, and Fabian Schwartau Adv. Radio Sci., 15, 1-9, https://doi.org/10.5194/ars-15-1-2017, 2017 A cost-effective and universal FMCW radar is developed for the RF characterisation of wind turbine plants. This radar is modular and can be easily adapted for different measurement tasks. A long-term goal is to investigate high-frequency characteristics of wind turbines at different locations by their Doppler spectrum. The results obtained will be used to derive a statistical model.
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  • 5
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    Copernicus
    Publication Date: 2018-03-05
    Description: Comparison of non-convex cost functionals for the consideration of phase differences in phaseless near-field far-field transformations of measured antenna fields Josef Knapp, Alexander Paulus, Carlos Lopez, and Thomas F. Eibert Adv. Radio Sci., 15, 11-19, https://doi.org/10.5194/ars-15-11-2017, 2017 This work introduces two methods which extend the non-convex minimization problem arising in phaseless (NF) far-field (FF) transformations. With the new extensions, knowledge about phase differences between measurement points can be incorporated into the minimization problem. The additional information helps to avoid stationary points of the minimization cost functional which would otherwise compromise the result of the near-field far-field transformation. The methods are incorporated into the Fast Irregular Antenna Field Transformation Algorithm (FIAFTA), analyzed and compared. Their effectiveness is shown by transforming synthetic near-field data sets with partial knowledge of phase differences to the far-field.
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  • 6
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    Copernicus
    Publication Date: 2018-03-05
    Description: Physical optics and full-wave simulations of transmission of electromagnetic fields through electrically large planar meta-sheets Ezgi Öziş, Andrey V. Osipov, and Thomas F. Eibert Adv. Radio Sci., 15, 29-35, https://doi.org/10.5194/ars-15-29-2017, 2017 Meta-sheets open up new opportunities in the design of radomes for microwave antennas. A meta-sheet typically consists of a periodic array of small resonators embedded in a thin dielectric layer. The smallness of unit cells and the large electrical size of microwave radomes significantly complicate full-wave numerical simulations as a very fine sampling over a large area is required. This paper proposes an efficient simulation approach, which combines Physical Optics and Finite Element methods.
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  • 7
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    Copernicus
    Publication Date: 2018-03-05
    Description: Behavioral modeling of nonlinear transfer systems with load-dependent X -parameters Seyed Mohammadamin Moosavi, Christian Widemann, and Wolfgang Mathis Adv. Radio Sci., 15, 37-41, https://doi.org/10.5194/ars-15-37-2017, 2017 In this contribution, different approaches based on the X -parameters TM to model the behavior of mismatched nonlinear transfer systems are examined. The X -parameters based on the PHD 1 -principle introduced by Verspecht and Root (2006) as an extension of the well-known S -parameters describe nonlinear microwave 2-port-networks under large signal conditions. Using load-pull measurement techniques they can be used for arbitrary load situations. Beside this load-pull approach, in the work of Cai et al. (2015), it is stated that it is sufficient to use one optimized X -parameter set for each value of the load reflection coefficient without introducing a large error. In another contribution of Cai and Yu (2015), this approach is extended to cover the whole smith chart with one optimized X -parameter set instead. In this work, these different approaches are compared and brought into question. 1 polyharmonic distortion; Verspecht and Root (2006).
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  • 8
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    Copernicus
    Publication Date: 2018-03-05
    Description: Advanced design and characterization methodologies for memory-aware CMOS power-amplifier implementation Martin Schleyer, Dominic Maurath, Heinrich Klar, and Friedel Gerfers Adv. Radio Sci., 15, 49-54, https://doi.org/10.5194/ars-15-49-2017, 2017 This paper reports on an effective root-cause analysis method of memory effects in power amplifiers, as well as introduces compensation techniques on a circuit design level. Despite conventional memory-effect approaches, the discussed method uses a two-tone scan over a wide operation and modulation range. The approach is demonstrated on a 65-nm CMOS power amplifier with an OIP1 of 27 dBm and a PAE of over 30 % using WCDMA and LTE signals.
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  • 9
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    Copernicus
    Publication Date: 2018-03-05
    Description: Sparse representation discretization errors in multi-sensor radar target motion estimation Hossein Azodi, Uwe Siart, and Thomas F. Eibert Adv. Radio Sci., 15, 69-76, https://doi.org/10.5194/ars-15-69-2017, 2017 This work investigates the errors, numerically and analytically, which occur due to the discretization of surveillance space in a multi-sensor radar system. The result of these investigations help to imprve the efficiency of the well-known compressed sensing algorithms. The improvement is critical for the cases where the signal processing algorithms must deliver the results within very short time intervals, e.g. 5 milliseconds or less.
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  • 10
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    Copernicus
    Publication Date: 2018-03-05
    Description: A Novel Target-Height Estimation Approach Using Radar-Wave Multipath Propagation for Automotive Applications Amir Laribi, Markus Hahn, Jürgen Dickmann, and Christian Waldschmidt Adv. Radio Sci., 15, 61-67, https://doi.org/10.5194/ars-15-61-2017, 2017 This paper introduces a novel target height estimation approach using a Frequency Modulation Continuous Wave (FMCW) automotive radar. The presented algorithm takes advantage of radar wave multipath propagation to measure the height of objects in the vehicle surroundings. A multipath propagation model is presented first, then a target height is formulated using geometry, based on the presented propagation model. It is then shown from Sensor-Target geometry that height estimation of targets is highly dependent on the radar range resolution, target range and target height. The high resolution algorithm RELAX is discussed and applied to collected raw data to enhance the radar range resolution capability. This enables a more accurate height estimation especially for low targets. Finally, the results of a measurement campaign using corner reflectors at different heights are discussed to show that target heights can be very accurately resolved by the proposed algorithm and that for low targets an average mean height estimation error of 0.03 m has been achieved by the proposed height finding algorithm.
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  • 11
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    Copernicus
    Publication Date: 2018-03-05
    Description: State of charge classification for lithium-ion batteries using impedance based features Marian Patrik Felder and Jürgen Götze Adv. Radio Sci., 15, 93-97, https://doi.org/10.5194/ars-15-93-2017, 2017 Currently, the electrification of the drive train of passenger cars takes place, and the task of obtaining precise knowledge about the condition of the on board batteries gains importance. Due to internal characteristics, several existing methods cannot be used. This work describes an impedance based approach using the Taylor Fourier transformation. The parameters extracted by the method can be used as features in machine learning algorithms.
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  • 12
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    Copernicus
    Publication Date: 2018-03-05
    Description: Implementation of envelope detection based Wake-Up Receiver for IEEE 802.15.4 WPAN from off-the-shelf components Josua Arndt, Lukas Krystofiak, Vahid Bonehi, Ralf Wunderlich, and Stefan Heinen Adv. Radio Sci., 15, 107-113, https://doi.org/10.5194/ars-15-107-2017, 2017 Power consumption in wireless networks is crucial. In most scenarios the transmission time is short compared to the idle listening time for data transmission, the most power is consumed by the receiver. In low latency systems there is a need for low power wake-up receivers (WuRx) that reduce the power consumption when the node is idle, but keep it responsive. This work presents a WuRx designed out of commercial components to investigate the needs of a WuRx when it is embedded in a WPAN.
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  • 13
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    Copernicus
    Publication Date: 2018-03-05
    Description: Wind regimes and their relation to synoptic variables using self-organizing maps Sigalit Berkovic Adv. Sci. Res., 15, 1-9, https://doi.org/10.5194/asr-15-1-2018, 2018 This study exemplifies the ability of the self-organizing maps method to directly define well known wind regimes over Israel during the entire year, except summer, period at 12:00 UTC. This procedure may be applied at other hours and is highly relevant to future automatic climatological analysis and applications. The investigation is performed by analysing surface wind measurements. The relation between the synoptic variables and the wind regimes is revealed from composite calculations.
    Print ISSN: 1992-0628
    Electronic ISSN: 1992-0636
    Topics: Natural Sciences in General
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  • 14
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    Copernicus
    Publication Date: 2018-03-05
    Description: Deriving evaluation indicators for knowledge transfer and dialogue processes in the context of climate research Renate Treffeisen, Klaus Grosfeld, and Franziska Kuhlmann Adv. Sci. Res., 14, 313-322, https://doi.org/10.5194/asr-14-313-2017, 2017 Knowledge transfer and dialogue processes (KT) in the field of climate science have captured intensive attention. This paper aims to serve as an input to stimulate further reflection on the field of evaluation of KT in the context of climate sciences. We carry out an analysis of three example activities and derive a set of indicators for measuring the output/outcome by balancing the wide diversity and range of activity contents as well as the different tools to realize them.
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    Topics: Natural Sciences in General
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  • 15
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    Copernicus
    Publication Date: 2018-03-05
    Description: Evaluating co-creation of knowledge: from quality criteria and indicators to methods Susanne Schuck-Zöller, Jörg Cortekar, and Daniela Jacob Adv. Sci. Res., 14, 305-312, https://doi.org/10.5194/asr-14-305-2017, 2017 Climate services and other fields, that are used to integrate the users in research activities (co-creation), are pledging for existing evaluation methods to be widened up. The authors harmonize the different elements of evaluation in an evaluation cascade , scaling down from very general evaluation dimensions to tangible assessment methods and suggest how to proceed in developing evaluation criteria and indicators. Two examples demonstrate how co-creation of knowledge could be assessed.
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  • 16
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    Copernicus
    Publication Date: 2018-03-05
    Description: Stakeholder-based evaluation categories for regional climate services – a case study at the German Baltic Sea coast Insa Meinke Adv. Sci. Res., 14, 279-291, https://doi.org/10.5194/asr-14-279-2017, 2017 In this study, categories, dimensions and criteria for evaluating regional climate services are derived by a participatory approach with potential service users at the German Baltic Sea coast. The results show that stakeholders do mainly address other components than those found in the literature. This might indicate that an evaluation, following solely literature-based (non-participative) components, is not sufficient to localize deficiencies or efficiencies within a regional climate service.
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    Topics: Natural Sciences in General
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  • 17
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    Copernicus
    Publication Date: 2018-03-05
    Description: The smoothing effect for renewable resources in an Afro-Eurasian power grid Maria Krutova, Alexander Kies, Bruno U. Schyska, and Lueder von Bremen Adv. Sci. Res., 14, 253-260, https://doi.org/10.5194/asr-14-253-2017, 2017 Renewable power systems have to cope with highly variable generation. Increasing the spatial extent of an interconnected power transmission grid smooths the feed-in by exchange of excess energy over long distances and therefore supports renewable power integration. In this work, we investigate and quantify the balancing potential of a supergrid covering Europe, Africa and Asia. We use ten years of historical weather data to model the interplay of renewable generation and consumption and show that a pan-continental Afro-Eurasian supergrid can smooth renewable generation to a large extent and reduce the need for backup energy by around 50 %. In addition, we show that results for different weather years vary by up to approximately 50 %.
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    Topics: Natural Sciences in General
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  • 18
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    Copernicus
    Publication Date: 2018-03-05
    Description: Deriving user-informed climate information from climate model ensemble results Heike Huebener, Peter Hoffmann, Klaus Keuler, Susanne Pfeifer, Hans Ramthun, Arne Spekat, Christian Steger, and Kirsten Warrach-Sagi Adv. Sci. Res., 14, 261-269, https://doi.org/10.5194/asr-14-261-2017, 2017 There is still a large gap between climate research results and their use in climate impact research and policy advisory. One of the many approaches taken to reduce this gap was a midterm user workshop of the German project ReKliEs-De. The users were asked to guide the further project work towards their needs. Conclusions from the workshop included the need for more plain text guidance on climate model strengths and weaknesses as well as more research on climate impact system functioning.
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  • 19
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    Copernicus
    Publication Date: 2018-03-05
    Description: Civil protection and Damaging Hydrogeological Events: comparative analysis of the 2000 and 2015 events in Calabria (southern Italy) Olga Petrucci, Tommaso Caloiero, Angela Aurora Pasqua, Piero Perrotta, Luigi Russo, and Carlo Tansi Adv. Geosci., 44, 101-113, https://doi.org/10.5194/adgeo-44-101-2017, 2017 This work presents a methodological approach to perform the comparative analysis of 2 events affecting the Calabria region (southern Italy), by collecting all the qualitative and quantitative features useful to describe both rain and damage. The first event occurred between 8 and 10 September 2000 while the second event occurred between 30 October and 1 November 2015. We concluded that, in the 2015 event, the management of pre-event phases allowed to reduce the number of victims.
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  • 20
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    Copernicus
    Publication Date: 2018-03-05
    Description: Flood and landslide warning based on rainfall thresholds and soil moisture indexes: the HEWS (Hydrohazards Early Warning System) for Sicily Giuseppina Brigandì, Giuseppe Tito Aronica, Brunella Bonaccorso, Roberto Gueli, and Giuseppe Basile Adv. Geosci., 44, 79-88, https://doi.org/10.5194/adgeo-44-79-2017, 2017 The paper presents the flood and landslide early warning system HEWS developed by the University of Messina for the Integrated Multi-Risk Decentralised Functional Centre of Sicily (Italy). HEWS implements a methodology based on the combined use of rainfall thresholds, soil moisture modelling and quantitative precipitation forecast (QPF) to issue alert bulletins both for floods and landslide. The software Delft-FEWS has been adopted as operation platform to support the implementation of HEWS.
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  • 21
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    Copernicus
    Publication Date: 2018-03-05
    Description: Effects of damaging hydrogeological events on people throughout 15 years in a Mediterranean region Luigi Aceto, A. Aurora Pasqua, and Olga Petrucci Adv. Geosci., 44, 67-77, https://doi.org/10.5194/adgeo-44-67-2017, 2017 Damaging Hydrogeological Events (DHE) are defined as rainy periods during which landslides and floods can damage people. The paper investigated the effects of DHE on people living in Calabria (southern Italy) in the period 2000–2014, using data coming from the systematic survey of regional newspapers. Data about fatalities , people injured and people involved (not killed neither hurt) were stored in the database named PEOPLE, made of three sections: (1) event identification, (2) victim-event interaction, (3) effects on people. The outcomes highlighted vulnerability factors related to gender and age: males were killed more frequently (75 %) than females (25 %), and fatalities were older (average age 49 years) than injured (40.1 years) and involved people (40.5 years). The average ages of females killed (67.5 years), injured (43.4 years) and involved (44.6 years) were higher than the same values assessed for males, maybe indicating that younger females tended to be more cautious than same-age males, while older females showed an intrinsic greater vulnerability. Involved people were younger than injured people and fatalities, perhaps because younger people show greater promptness to react in dangerous situations. In the study region, floods caused more fatalities (67.9 %), injured (55 %) and involved people (55.3 %) than landslides. Fatalities and injuries mainly occurred outdoor, especially along roads, and the most dangerous dynamic was to be dragged by flood , causing the majority of fatalities (71.4 %). These outcomes can be used to strengthen the strategies aimed at saving people, and to customise warning campaigns according to the local risk features and people's behaviour. The results can improve the understanding of the potential impacts of geo-hydrological hazards on the population and can increase risk awareness among both administrators and citizens.
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  • 22
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    Copernicus
    Publication Date: 2018-03-05
    Description: Comparison of digital beamforming algorithms for 3-D terahertz imaging with sparse multistatic line arrays Bessem Baccouche, Patrick Agostini, Falco Schneider, Wolfgang Sauer-Greff, Ralph Urbansky, and Fabian Friederich Adv. Radio Sci., 15, 283-292, https://doi.org/10.5194/ars-15-283-2017, 2017 In this contribution we compare the back-projection algorithm with our recently developed modified range migration algorithm for 3D terahertz imaging using sparse multistatic line arrays. Numerical and experimental investigations show that imaging results from the proposed range migration algorithm approximates very nicely these of the back-projection algorithm, yet with a significant computational saving. These results are appealing for time critical 3D terahertz imaging.
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  • 23
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    Copernicus
    Publication Date: 2018-03-05
    Description: Results of an intercomparison for electric field strength measurements within the German calibration service Reiner Pape, Uwe Karsten, Frank-Michael Lindner, Frank Rittmann, Joachim von Freeden, Thomas Kleine-Ostmann, and Thorsten Schrader Adv. Radio Sci., 15, 243-248, https://doi.org/10.5194/ars-15-243-2017, 2017 We discuss the results of an intercomparison for electric field strength measurements within the DKD. The comparison has been carried out on the field strength value required to reach a display reading of 20 V m −1 of the field probes. While the results agree well for the small field probe and when the larger commercial 3-axis field probe is oriented in the direction of the magnetic field, larger deviations occur, when the larger 3-axis field probe is oriented into the direction propagation.
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  • 24
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    Copernicus
    Publication Date: 2018-03-05
    Description: A 24 GHz Waveguide based Radar System using an Advanced Algorithm for I/Q Offset Cancelation Christoph Will, Sarah Linz, Sebastian Mann, Fabian Lurz, Stefan Lindner, Robert Weigel, and Alexander Koelpin Adv. Radio Sci., 15, 249-258, https://doi.org/10.5194/ars-15-249-2017, 2017 This paper presents a guided wave Six-Port interferometric radar system with integrated I/Q offset cancelation. An intelligent algorithm is proposed which optimally adjusts three voltage controlled attenuators and one voltage controlled phase shifter in the radio frequency part of the system. By minimizing the I/Q offset, the standard deviation as well as the relative error are decreased in comparison to an uncompensated measurement setup.
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  • 25
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    Publication Date: 2018-03-05
    Description: Differential form representation of stochastic electromagnetic fields Michael Haider and Johannes A. Russer Adv. Radio Sci., 15, 21-28, https://doi.org/10.5194/ars-15-21-2017, 2017 In this work, we revisit the theory of stochastic electromagnetic fields using exterior differential forms. We present a short overview as well as a brief introduction to the application of differential forms in electromagnetic theory. Within the framework of exterior calculus we derive equations for the second order moments, describing stochastic electromagnetic fields. Since the resulting objects are continuous quantities in space, a discretization scheme based on the Method of Moments (MoM) is introduced for numerical treatment. The MoM is applied in such a way, that the notation of exterior calculus is maintained while we still arrive at the same set of algebraic equations as obtained for the case of formulating the theory using the traditional notation of vector calculus. We conclude with an analytic calculation of the radiated electric field of two Hertzian dipole, excited by uncorrelated random currents.
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  • 26
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    Publication Date: 2018-03-05
    Description: Discretization analysis of bifurcation based nonlinear amplifiers Sven Feldkord, Marco Reit, and Wolfgang Mathis Adv. Radio Sci., 15, 43-47, https://doi.org/10.5194/ars-15-43-2017, 2017 Recently, for modeling biological amplification processes, nonlinear amplifiers based on the Andronov–Hopf bifurcation have become a focus of attention. In this contribution, we analyze discrete-time implementations of this type of amplifiers. The effects of the time-discretization by explicit integration methods are discussed. A novel discrete-time system based on the Neimark–Sacker bifurcation is introduced, that outstandingly approximates the behavior of a particular Hopf-type amplifier.
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  • 27
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    Publication Date: 2018-03-05
    Description: Electrostatic sensor modeling for torque measurements Michał Mika, Mirjam Dannert, Felix Mett, Harry Weber, Wolfgang Mathis, and Udo Nackenhorst Adv. Radio Sci., 15, 55-60, https://doi.org/10.5194/ars-15-55-2017, 2017 Torque load measurements play an important part in various engineering applications, as for automotive industry, in which the drive torque of a motor has to be determined. A widely used measuring method are strain gauges. A thin flexible foil, which supports a metallic pattern, is glued to the surface of the object the torque is being applied to. In case of a deformation due to the torque load, the change in the electrical resistance is measured. With the combination of constitutive equations the applied torque load is determined by the change of electrical resistance. The creep of the glue and the foil material, together with the temperature and humidity dependence, may become an obstacle for some applications Kapralov and Fesenko (1984). Thus, there have been optical and magnetical, as well as capacitive sensors introduced). This paper discusses the general idea behind an electrostatic capacitive sensor based on a simple draft of an exemplary measurement setup. For better understanding an own electrostatical, geometrical and mechanical model of this setup has been developed.
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  • 28
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    Copernicus
    Publication Date: 2018-03-05
    Description: Novel post-Doppler STAP with a priori knowledge information for traffic monitoring applications: basic idea and first results André B. C. da Silva and Stefan V. Baumgartner Adv. Radio Sci., 15, 77-82, https://doi.org/10.5194/ars-15-77-2017, 2017 This paper presents a novel algorithm for traffic monitoring applications, where the powerful post-Doppler space-time adaptive processing (PD STAP) is combined with the OpenStreetMap database. The road map is applied after the PD STAP for recognizing and rejecting false detections, and for repositioning off-road vehicles. The algorithm was tested using real multi-channel data acquired by DLR’s airborne F-SAR. The experimental results are shown and discussed, and the novelties are highlighted.
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  • 29
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    Copernicus
    Publication Date: 2018-03-05
    Description: Lithium-ion battery models: a comparative study and a model-based powerline communication Fida Saidani, Franz X. Hutter, Rares-George Scurtu, Wolfgang Braunwarth, and Joachim N. Burghartz Adv. Radio Sci., 15, 83-91, https://doi.org/10.5194/ars-15-83-2017, 2017 This paper presents a comparative overview of models for lithium-ion batteries from an electrical Engineering Point of view. The comparison criteria and the different models are presented. After this comparison, a model is used to establish a new communication concept.
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  • 30
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    Publication Date: 2018-03-05
    Description: Orthogonal frequency division multiplexing with amplitude shift keying subcarrier modulation as a reliable and efficient transmission scheme for self-mixing receivers Jonas Kornprobst, Thomas J. Mittermaier, and Thomas F. Eibert Adv. Radio Sci., 15, 99-106, https://doi.org/10.5194/ars-15-99-2017, 2017 By analyzing the behavior of a self-mixing receiver, an appropriate model with a squre-law device can be obtained. This model is analyzed and a novel transmission technique with higher spectral efficiency is deduced by the formulation of the signal reconstruction problem as a phase retrival problem. Simulation results show the good performance of the proposed method.
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  • 31
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    Publication Date: 2018-03-05
    Description: Applications of a shadow camera system for energy meteorology Pascal Kuhn, Stefan Wilbert, Christoph Prahl, Dominik Garsche, David Schüler, Thomas Haase, Lourdes Ramirez, Luis Zarzalejo, Angela Meyer, Philippe Blanc, and Robert Pitz-Paal Adv. Sci. Res., 15, 11-14, https://doi.org/10.5194/asr-15-11-2018, 2018 Downward-facing shadow cameras might play a major role in future energy meteorology. Shadow cameras image shadows directly on the ground from an elevated position. They are used to validate other systems (e.g. all-sky imager based nowcasting systems, cloud speed sensors or satellite forecasts) and can potentially provide short term forecasts for solar power plants. Such forecasts are needed for electricity grids with high penetrations of renewable energy and solar power plants.
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    Topics: Natural Sciences in General
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  • 32
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    Publication Date: 2018-03-05
    Description: An interoperable research data infrastructure to support climate service development Tiziana De Filippis, Leandro Rocchi, and Elena Rapisardi Adv. Sci. Res., 14, 335-340, https://doi.org/10.5194/asr-14-335-2018, 2018 Accessibility, availability, re-use and re-distribution of scientific data are prerequisites to build climate services across Europe. The proposed architecture uses open-source tools and interoperable standards to ensure sustainability in the development and deployment of Web applications. The availability of structured raw data as customized information paves the way for building climate service purveyors to support adaptation, mitigation and risk management at different scales.
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  • 33
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    Publication Date: 2018-03-05
    Description: Modelling Glaciers in the HARMONIE-AROME NWP model Ruth Mottram, Kristian Pagh Nielsen, Emily Gleeson, and Xiaohua Yang Adv. Sci. Res., 14, 323-334, https://doi.org/10.5194/asr-14-323-2017, 2017 The HARMONIE weather forecasting model is used successfully in Greenland, but there are some problems over the ice sheet due to the lack of realistic glacier surface characteristics. By introducing a correction to the model, preventing glacier surface temperatures over 0 °C, we improve both 2 m air temperature and the surface winds (both strength and direction) forecast by the model. We also identify other corrections needed before HARMONIE can be used for climate and ice sheet modelling.
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  • 34
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    Publication Date: 2018-03-05
    Description: Risk management perspective for climate service development – Results from a study on Finnish organizations Atte Harjanne, Riina Haavisto, Heikki Tuomenvirta, and Hilppa Gregow Adv. Sci. Res., 14, 293-304, https://doi.org/10.5194/asr-14-293-2017, 2017 Weather, climate and climate change can cause significant risks to businesses and public administration. By asking Finnish organizations about their weather and climate risk perceptions and management, this study aims to improve ways climate services can support in adapting to current and future climate. The results indicate that climate risk management is often de-centralized and relies on expert networks but that practices differ between actors.
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  • 35
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    Publication Date: 2018-03-06
    Description: Aerosol indirect effects on summer precipitation in a regional climate model for the Euro-Mediterranean region Nicolas Da Silva, Sylvain Mailler, and Philippe Drobinski Ann. Geophys., 36, 321-335, https://doi.org/10.5194/angeo-36-321-2018, 2018 Aerosols affect atmospheric dynamics because they absorb radiations (direct effects) and because they act as cloud condensation nuclei (indirect effects). The present study shows that aerosol indirect effects reduce summer precipitation in the Euro-Mediterranean region through reduction of the radiative heating of the surface and corresponding reductions of surface temperature, resulting in increased atmospheric stability in the presence of high aerosol loads.
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  • 36
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    Publication Date: 2018-03-06
    Description: Mesopause region temperature variability and its trend in southern Brazil Mateus S. Venturini, José V. Bageston, Nattan R. Caetano, Lucas V. Peres, Hassan Bencherif, and Nelson J. Schuch Ann. Geophys., 36, 301-310, https://doi.org/10.5194/angeo-36-301-2018, 2018 In the past years, the study of the temperature trend and its variability in the upper atmosphere has increased. However, most works were conducted in regions of medium and high latitude. Therefore, we aim to analyze a low-latitude region, the south of Brazil and surrounding areas. Using data from the TIMED/SABER instrument and applying the Trend-Run model for temperature trend analyses, no substantial temperature trend was found in the MLT region (80–100 km) from the years 2003 to 2014.
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  • 37
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    Publication Date: 2018-03-06
    Description: Case study of mesospheric front dissipation observed over the northeast of Brazil Amauri Fragoso Medeiros, Igo Paulino, Cristiano Max Wrasse, Joaquim Fechine, Hisao Takahashi, José Valentin Bageston, Ana Roberta Paulino, and Ricardo Arlen Buriti Ann. Geophys., 36, 311-319, https://doi.org/10.5194/angeo-36-311-2018, 2018 On 3 October 2005, a mesospheric front was observed over São João do Cariri (7.4° S, 36.5° W) propagating to the northeast in the OH airglow images. One and a half hours later, it disappeared completely and ripples were observed in the eastern part of the images. After studying the background atmosphere, the main conclusion of this work was that the instability in the airglow layer did not allow the propagation of the front to the other side of the local zenith.
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  • 38
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    Publication Date: 2018-03-06
    Description: Intrinsic parameters of periodic waves observed in the OI6300 airglow layer over the Brazilian equatorial region Igo Paulino, Joyrles F. Moraes, Gleuson L. Maranhão, Cristiano M. Wrasse, Ricardo Arlen Buriti, Amauri F. Medeiros, Ana Roberta Paulino, Hisao Takahashi, Jonathan J. Makela, John W. Meriwether, and José André V. Campos Ann. Geophys., 36, 265-273, https://doi.org/10.5194/angeo-36-265-2018, 2018 This article presents characteristics of periodic waves observed in the thermosphere from airglow images collected in the Northeast of Brazil. Using simultaneous measurements of the background wind in the airglow emission altitudes, it was possible to estimate the intrinsic parameters and the role of the wind in the propagation of the waves into the thermosphere. An anisotropy in the propagation direction of the waves was observed and it could be explained by the wind filtering process.
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  • 39
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    Publication Date: 2018-03-06
    Description: A statistical study of spatial distribution and source region size of chorus waves using Van Allen Probes data Shangchun Teng, Xin Tao, Wen Li, Yi Qi, Xinliang Gao, Lei Dai, Quanming Lu, and Shui Wang Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-16,2018 Manuscript under review for ANGEO (discussion: open, 0 comments) Spatial distribution and source region size of chorus waves are important parameters in understanding their generation.In this work, we analyze over 3 years of continuous wave burst mode data from Van Allen Probes and build a data set of rising and falling tone chorus. For the L shell range covered by Van Allen Probes data (3.5 ≤  L  ≤ 7), statistical results demonstrate that the sector where rising tones are most likely to be observed is the dayside during geomagnetically quiet and moderate times and the dawnside during active times. Moreover, rising tone chorus waves have a higher occurrence rate near the equatorial plane, while the falling tone chorus waves have a higher possibility to be observed at lower L -shell and higher magnetic latitude. By analyzing the direction of Poynting wave vector, we statistically investigate the chorus source region size along a field line, and compare the results with previous theoretical estimates. Our analysis confirms previous conclusions that both rising tone and falling tone chorus waves are generated near the equatorial plane, and shows that previous theoretical estimates roughly agree with the observation within a factor of two. Our results provide important insights into further understanding of chorus generation.
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  • 40
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    Publication Date: 2018-03-06
    Description: Case study of ozone anomalies over northern Russia in the 2015/2016 winter: Measurements and numerical modeling Yury M. Timofeyev, Sergei P. Smyshlyaev, Yana A. Virolainen, Alexander S. Garkusha, Alexander V. Polyakov, Maxim A. Motsakov, and Ole Kirner Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-15,2018 Manuscript under review for ANGEO (discussion: open, 0 comments) Atmospheric ozone plays a vital role, absorbing the ultraviolet Sun radiation and heating the air, thus forming the stratosphere itself. If not absorbed, UV radiation would reach Earth surface in amounts that are harmful to a variety of life-forms. Climate change may lead to increasing ozone depletion especially in Arctic. Observation and prediction of the ozone variability is both crucial for the investigation of its nature and for the prediction of potential increase of surface UV-radiation.
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  • 41
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    Publication Date: 2018-03-06
    Description: Ultrafast Kelvin waves in the MLT airglow and wind, and their interaction with the atmospheric tides Fabio Egito, Ricardo Arlen Buriti, Amauri Fragoso Medeiros, and Hisao Takahashi Ann. Geophys., 36, 231-241, https://doi.org/10.5194/angeo-36-231-2018, 2018 Airglow and wind measurements from the Brazilian equatorial region were used to investigate the presence and the effects of the 3–4-day ultrafast Kelvin waves in the MLT. The airglow integrated intensities of the OI557.7 nm, O 2 b(0-1) and OH(6-2) emissions, as well as the OH rotational temperature, were measured by a multichannel photometer, and the zonal and meridional wind components between 80 and 100 km were obtained from a meteor radar. Both instruments are installed in the Brazilian equatorial region at São João do Cariri (7.4° S, 36.5° W). Data from 2005 were used in this study. The 3–4-day oscillations appear intermittently throughout the year in the airglow. They were identified in January, March, July, August and October–November observations. The amplitudes induced by the waves in the airglow range from 26 to 40 % in the OI557.7 nm, 17 to 43 % in the O 2 b(0-1) and 15 to 20 % in the OH(6-2) emissions. In the OH rotational temperature, the amplitudes were from 4 to 6 K. Common 3–4-day oscillations between airglow and neutral wind compatible with ultrafast Kelvin waves were observed in March, August and October–November. In these cases, the amplitudes in the zonal wind were found to be between 22 and 28 m s −1 and the vertical wavelength ranges from 44 to 62 km. Evidence of the nonlinear interaction between the ultrafast Kelvin wave and diurnal tide was observed.
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  • 42
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    Publication Date: 2018-03-06
    Description: Seasonal variability of atmospheric tides in the mesosphere and lower thermosphere: meteor radar data and simulations Dimitry Pokhotelov, Erich Becker, Gunter Stober, and Jorge L. Chau Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-17,2018 Manuscript under review for ANGEO (discussion: open, 0 comments) Atmospheric tides are produced by solar heating of the lower atmosphere. The tides propagate to upper atmosphere and ionosphere playing an important role in the vertical coupling. Ground radar measurements of the seasonal variability of tides are compared with global numerical simulations. The agreement with radar data and limitations of the numerical model are discussed. The work represents a first step in modelling the impact of tidal dynamics on the upper atmosphere and ionosphere.
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  • 43
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    Publication Date: 2018-03-06
    Description: Monitoring potential ionosphere changes caused by Van earthquake (Mw 7.2) using GNSS measurements Selcuk Peker, Samed Inyurt, and Cetin Mekik Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-11,2018 Manuscript under review for ANGEO (discussion: open, 0 comments) Several scientists from different disciplines have studied earthquakes for many years. As a result of these studies, it has been proposed that some changes take place in the ionosphere layer before, during or after earthquakes, and the ionosphere should be monitored in earthquake prediction studies. This study investigates the changes in the ionosphere created by the earthquake with magnitude of Mw=7.2 in the northwest of the Lake Erçek which is located to the north of the province of Van in Turkey on 23 October 2011 and at 1.41 pm local time (−3 UT) with the epicenter of 38.758° N, 43.360° E using the TEC values obtained by the Global Ionosphere Models (GIM) created by IONOLAB-TEC and CODE. In order to see whether the ionospheric changes obtained by the study in question were caused by the earthquake or not, the ionospheric conditions were studied by utilizing indices providing information on solar and geomagnetic activities (F10.7 cm, Kp, Dst). As a result of the statistical test on the TEC values obtained from the both models, positive and negative anomalies were obtained for the times before, on the day of and after the earthquake, and the reasons for these anomalies are discussed in detail in the last section of the study. As the ionospheric conditions in the analyzed days were highly vibrant, it was thought that the anomalies were caused by geomagnetic effects, solar activity and the earthquake. The authors believe that interdisciplinary studies are needed to distinguish the earthquake-related part of the anomalies in question.
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  • 44
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    Publication Date: 2018-03-06
    Description: The geomagnetic coast effect at two 80° S stations in Antarctica, observed in the ULF range Mauro Regi, Marcello De Lauretis, Patrizia Francia, Stefania Lepidi, Andrea Piancatelli, and Stefano Urbini Ann. Geophys., 36, 193-203, https://doi.org/10.5194/angeo-36-193-2018, 2018 Our results suggest that sea–land interface affects the polarization parameters at coastal stations. We proposed a method for directly estimating, in the frequency domain, the normal field variations at coastal stations, by inverting the linear relationship between horizontal field measurements at coastal and reference stations. Our techniques could also be used to detect possible anomalous effects due to sporadic changes in ground conductivity.
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  • 45
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    Publication Date: 2018-03-06
    Description: Increasing persistent haze in Beijing: potential impacts of weakening East Asian winter monsoons associated with northwestern Pacific sea surface temperature trends Lin Pei, Zhongwei Yan, Zhaobin Sun, Shiguang Miao, and Yao Yao Atmos. Chem. Phys., 18, 3173-3183, https://doi.org/10.5194/acp-18-3173-2018, 2018 This paper demonstrates the increasing frequency of persistent haze events (PHE) in Beijing based on updated observations and explores the associated changes in large-scale atmospheric circulations with possible links to the large-scale warming trend. We propose a more concrete observation-based mechanism for explaining how the local PHE in Beijing change with large-scale climate warming via the sea surface temperature anomaly in the northwestern Pacific.
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  • 46
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    Publication Date: 2018-03-06
    Description: Aircraft Observations of Aerosol in the Manaus Urban Plume and Surrounding Tropical Forest during GoAmazon 2014/15 John E. Shilling, Mikhail S. Pekour, Edward C. Fortner, Paulo Artaxo, Suzane de Sá, John M. Hubbe, Karla M. Longo, Luiz A. T. Machado, Scot T. Martin, Stephen R. Springston, Jason Tomlinson, and Jian Wang Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-193,2018 Manuscript under review for ACP (discussion: open, 0 comments) We report aircraft observations of the evolution of organic aerosol in the Manaus urban plume as it ages. We observe dynamic changes in the organic aerosol. The mean carbon oxidation state of the OA increases from −0.6 to −0.45. Hydrocarbon-like organic aerosol (HOA) mass is lost and is balanced out by formation of oxygenated organic aerosol (OOA). Because HOA loss is balanced by OOA formation, we observe little change in the net Δorg/ΔCO values with aging.
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  • 47
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    Publication Date: 2018-03-06
    Description: Lower tropospheric ozone over India and its linkage to the South Asian monsoon Xiao Lu, Lin Zhang, Xiong Liu, Meng Gao, Yuanhong Zhao, and Jingyuan Shao Atmos. Chem. Phys., 18, 3101-3118, https://doi.org/10.5194/acp-18-3101-2018, 2018 Deteriorating tropospheric ozone pollution over India may not only affect local human health and vegetation but also perturb global ozone distribution. This study analyzes the processes controlling lower tropospheric ozone over India using OMI satellite observations (2006–2014) and model simulations (1990–2010). We show that the South Asian monsoon largely controls the seasonal cycle and interannual variability of Indian lower tropospheric ozone via changes in ozone production and transport.
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  • 48
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    Publication Date: 2018-03-06
    Description: Exploring the relationship between surface PM 2.5 and meteorology in Northern India Jordan L. Schnell, Vaishali Naik, Larry W. Horowitz, Fabien Paulot, Jingqiu Mao, Paul Ginoux, Ming Zhao, and Kirpa Ram Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-24,2018 Manuscript under review for ACP (discussion: open, 0 comments) We evaluate the ability of a developmental version of the NOAA GFDL Atmospheric Model, version 4 to simulate observed wintertime pollution and its relationship to weather over Northern India, one of the most densely populated and polluted regions in world. We also compare two emission inventories and find that the newest version dramatically improves our simulation. Observed and modeled pollution is the highest within the Indo-Gangetic Plain, where it is closely related to near-surface weather.
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  • 49
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    Publication Date: 2018-03-06
    Description: A high-resolution inventory of air pollutant emissions from crop residue burning in China Xiaohui Zhang, Yan Lu, Qin'geng Wang, and Xin Qian Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2017-1113,2018 Manuscript under review for ACP (discussion: open, 0 comments) Activity data at prefectural-city level combined with high-resolution land use data were adopted to improve spatial resolution and detailed crop rotations and harvest times in different regions were considered in determining temporal distribution. Also, MODIS fire products were applied to verify the spatial and temporal variations of the emissions. Results showed that high emissions were generally located in Eastern, Central and Northeastern China, and temporally peaking in June and October.
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  • 50
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    Publication Date: 2018-03-06
    Description: Technical Note: Atmospheric CO 2 inversions on the mesoscale using data-driven prior uncertainties: methodology and system evaluation Panagiotis Kountouris, Christoph Gerbig, Christian Rödenbeck, Ute Karstens, Thomas Frank Koch, and Martin Heimann Atmos. Chem. Phys., 18, 3027-3045, https://doi.org/10.5194/acp-18-3027-2018, 2018 Atmospheric inversions are widely used in the optimization of surface carbon fluxes on a regional scale using information from atmospheric CO 2 dry mole fractions. In many studies the prior flux uncertainty applied to the inversion schemes does not directly reflect the true flux uncertainties but is used to regularize the inverse problem. Here, we aim to implement an inversion scheme using the Jena inversion system and applying a prior flux error structure derived from a model–data residual analysis using high spatial and temporal resolution over a full year period in the European domain. We analyzed the performance of the inversion system with a synthetic experiment, in which the flux constraint is derived following the same residual analysis but applied to the model–model mismatch. The synthetic study showed a quite good agreement between posterior and true fluxes on European, country, annual and monthly scales. Posterior monthly and country-aggregated fluxes improved their correlation coefficient with the known truth by 7 % compared to the prior estimates when compared to the reference, with a mean correlation of 0.92. The ratio of the SD between the posterior and reference and between the prior and reference was also reduced by 33 % with a mean value of 1.15. We identified temporal and spatial scales on which the inversion system maximizes the derived information; monthly temporal scales at around 200 km spatial resolution seem to maximize the information gain.
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    Publication Date: 2018-03-06
    Description: Establishing the Impact of Model Surfactants on Cloud Condensation Nuclei Activity of Sea Spray Aerosols Sara D. Forestieri, Sean M. Staudt, Thomas M. Kuborn, Katharine Faber, Christopher R. Ruehl, Timothy H. Bertram, and Christopher D. Cappa Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-207,2018 Manuscript under review for ACP (discussion: open, 0 comments) Our work establishes how surface tension reduction influences droplet growth and activation of simple sea spray mimics, i.e. NaCl coated with fatty acids. Fatty acids can substantially reduce droplet surface tension near activation, but have limited impact on activation. Coating of NaCl by stearic acid (a wax) impedes water uptake, but this impedance is removed if oleic acid (a liquid) is mixed in. The properties that surface active compounds need to impact activation are theoretically examined.
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  • 52
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    Publication Date: 2018-03-06
    Description: Chemical characterization of laboratory-generated tar ball particles Ádám Tóth, András Hoffer, Mihály Pósfai, Tibor Ajtai, Zoltán Kónya, Marianne Blazsó, Zsuzsanna Czégény, Gyula Kiss, Zoltán Bozóki, and András Gelencsér Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-132,2018 Manuscript under review for ACP (discussion: open, 0 comments) Atmospheric tar balls are abundant particles in biomass smoke and were shown to be strongly light-absorbing. Being able to synthesize pure tar balls in the laboratory we deployed various analytical techniques to determine the chemical characteristics of tar balls and to compare them with those of other light-absorbing particle types such as soot (black carbon, BC). The results have relevance in better representing these specific smoke particles in global climate models.
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  • 53
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    Publication Date: 2018-03-06
    Description: Influence of anthropogenic emissions and boundary conditions on multi-model simulations of major air pollutants over Europe and North America in the framework of AQMEII3 Ulas Im, Jesper Heile Christensen, Camilla Geels, Kaj Mantzius Hansen, Jørgen Brandt, Efisio Solazzo, Ummugulsum Alyuz, Alessandra Balzarini, Rocio Baro, Roberto Bellasio, Roberto Bianconi, Johannes Bieser, Augustin Colette, Gabriele Curci, Aidan Farrow, Johannes Flemming, Andrea Fraser, Pedro Jimenez-Guerrero, Nutthida Kitwiroon, Peng Liu, Uarporn Nopmongcol, Laura Palacios-Peña, Guido Pirovano, Luca Pozzoli, Marje Prank, Rebecca Rose, Ranjeet Sokhi, Paolo Tuccella, Alper Unal, Marta G. Vivanco, Greg Yarwood, Christian Hogrefe, and Stefano Galmarini Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2017-1231,2018 Manuscript under review for ACP (discussion: open, 0 comments) We evaluate the impact of global and regional anthropogenic emission reductions on major air pollutant levels over Europe and North America, using a multi-model ensemble of regional chemistry and transport models. Results show that ozone levels are largely driven by long-range transport over both continents while other pollutants such as carbon monoxide or aerosols are mainly controlled by domestic sources. Use of multi model ensembles can help to reduce the uncertainties in individual models.
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  • 54
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    Publication Date: 2018-03-06
    Description: Investigating the yield of H 2 O and H 2 from methane oxidation in the stratosphere Franziska Frank, Patrick Jöckel, Sergey Gromov, and Martin Dameris Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-170,2018 Manuscript under review for ACP (discussion: open, 0 comments) Previously, it was assumed that one molecule of methane produces two water molecules. Applying various modeling concepts, we find that this overestimates the production in some areas of the atmosphere and underestimate it in other. Additionally, the chemical loss of water influences the actual abundance of it, especially in the upper atmosphere. We question the assumption of a vertically constant chemical production of water vapor and rather encourage to apply a sophisticated vertical profile.
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    Publication Date: 2018-03-06
    Description: Aerosol–cloud interactions in mixed-phase convective clouds – Part 1: Aerosol perturbations Annette K. Miltenberger, Paul R. Field, Adrian A. Hill, Phil Rosenberg, Ben J. Shipway, Jonathan M. Wilkinson, Robert Scovell, and Alan M. Blyth Atmos. Chem. Phys., 18, 3119-3145, https://doi.org/10.5194/acp-18-3119-2018, 2018 Changes induced by perturbed aerosol conditions in moderately deep mixed-phase convective clouds (cloud top height  ∼  5 km) developing along sea-breeze convergence lines are investigated with high-resolution numerical model simulations. The simulations utilise the newly developed Cloud–AeroSol Interacting Microphysics (CASIM) module for the Unified Model (UM), which allows for the representation of the two-way interaction between cloud and aerosol fields. Simulations are evaluated against observations collected during the COnvective Precipitation Experiment (COPE) field campaign over the southwestern peninsula of the UK in 2013. The simulations compare favourably with observed thermodynamic profiles, cloud base cloud droplet number concentrations (CDNC), cloud depth, and radar reflectivity statistics. Including the modification of aerosol fields by cloud microphysical processes improves the correspondence with observed CDNC values and spatial variability, but reduces the agreement with observations for average cloud size and cloud top height. Accumulated precipitation is suppressed for higher-aerosol conditions before clouds become organised along the sea-breeze convergence lines. Changes in precipitation are smaller in simulations with aerosol processing. The precipitation suppression is due to less efficient precipitation production by warm-phase microphysics, consistent with parcel model predictions. In contrast, after convective cells organise along the sea-breeze convergence zone, accumulated precipitation increases with aerosol concentrations. Condensate production increases with the aerosol concentrations due to higher vertical velocities in the convective cores and higher cloud top heights. However, for the highest-aerosol scenarios, no further increase in the condensate production occurs, as clouds grow into an upper-level stable layer. In these cases, the reduced precipitation efficiency (PE) dominates the precipitation response and no further precipitation enhancement occurs. Previous studies of deep convective clouds have related larger vertical velocities under high-aerosol conditions to enhanced latent heating from freezing. In the presented simulations changes in latent heating above the 0°C are negligible, but latent heating from condensation increases with aerosol concentrations. It is hypothesised that this increase is related to changes in the cloud field structure reducing the mixing of environmental air into the convective core. The precipitation response of the deeper mixed-phase clouds along well-established convergence lines can be the opposite of predictions from parcel models. This occurs when clouds interact with a pre-existing thermodynamic environment and cloud field structural changes occur that are not captured by simple parcel model approaches.
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    Publication Date: 2018-03-06
    Description: Aerosol optical properties over Europe: an evaluation of the AQMEII Phase 3 simulations against satellite observations Laura Palacios-Peña, Pedro Jiménez-Guerrero, Rocío Baró, Alessandra Balzarini, Roberto Bianconi, Gabriele Curci, Tony Christian Landi, Guido Pirovano, Marje Prank, Angelo Riccio, Paolo Tuccella, and Stefano Galmarini Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2017-1119,2018 Manuscript under review for ACP (discussion: open, 0 comments) The main uncertainties in estimates of changes in the Earth's energy budget are related to the role of atmospheric aerosols. These changes are caused mainly by aerosol-radiation (ARI) and aerosol-cloud interactions (ACI), which heavily depend on aerosol properties. From the 1980s, many international modelling initiatives have studied atmospheric aerosols and their climate effects. Phase 3 of the Air Quality Model Evaluation International Initiative (AQMEII) focuses on evaluating and intercomparing regional and linked global/regional modelling systems by collaborating with the Task Force on the Hemispheric Transport of Air Pollution Phase 2 (HTAP2) initiative. Within this framework, the main aim of this work was to evaluate the representation of aerosol optical depth (AOD) and the Ångström exponent (AE) by the AQMEII Phase 3 simulations over Europe. The evaluation was made using satellite data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on board the Terra and Aqua platforms. The results indicated that the skills of AQMEII simulations in the AOD representation produced fewer errors than in the AE. Regardless of the models and emissions used, models were skilful at representing the low and medium AOD values observed (below 0.5). However, high values (close to 1.0) were underestimated for biomass burning episodes, and were overestimated for desert dust contributions, related mainly to emission and boundary conditions. Despite this behaviour, the spatial and temporal variability of this variable was well-represented by all the models. Generally, the AE evaluation showed more serious errors than the AOD evaluation. Moreover, the observed variability of this parameter was strongly underestimated in all the simulations.
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    Publication Date: 2018-03-06
    Description: Contrasting the co-variability of daytime cloud and precipitation over tropical land and ocean Daeho Jin, Lazaros Oreopoulos, Dongmin Lee, Nayeong Cho, and Jackson Tan Atmos. Chem. Phys., 18, 3065-3082, https://doi.org/10.5194/acp-18-3065-2018, 2018 To what degree can precipitation be predicted given information about clouds? Or, conversely, with precipitation information at hand, can we provide good guesses about the clouds responsible? To answer these questions, we performed joint analysis of rainfall and cloud data, which are significantly decoupled. We find that only for the deepest and thickest clouds does cloud amount relate strongly with the intensity of rainfall, and that the details are different over oceans and land.
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  • 58
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    Publication Date: 2018-03-06
    Description: Source apportionment of atmospheric aerosol in a marine dusty environment by Ionic/composition Mass Balance (IMB) João Cardoso, Susana M. Almeida, Teresa Nunes, Marina Almeida-Silva, Mário Cerqueira, Célia Alves, Fernando Rocha, Paula Chaves, Miguel Reis, Pedro Salvador, Begoña Artiñano, and Casimiro Pio Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-10,2018 Manuscript under review for ACP (discussion: open, 0 comments) Atmospheric aerosol was sampled in Cape Verde islands and analysed for chemical composition. Very high levels of dust were measured during the winter months, as a result of transport from Africa. Mass Balances were applied to the particulate material, permitting the determination of 7 different source contributions to the aerosol loading. The balance methodology compared well with Standard Source Apportionment methods, showing its capability for the source apportionment of aerosol particles.
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  • 59
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    Publication Date: 2018-03-06
    Description: Field calibration of electrochemical NO 2 sensors in a citizen science context Bas Mijling, Qijun Jiang, Dave de Jonge, and Stefano Bocconi Atmos. Meas. Tech., 11, 1297-1312, https://doi.org/10.5194/amt-11-1297-2018, 2018 Although in many cities the population is exposed to air pollution, real-time air quality is usually only measured at a few locations. New low-cost sensor technology has the potential to extend the monitoring network significantly. We show that citizen science campaigns using the current generations of electrochemical NO 2 sensors may provide useful complementary data on local air quality in an urban setting, provided that experiments are properly set up and the data are carefully analysed.
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    Publication Date: 2018-03-06
    Description: Regional uncertainty of GOSAT XCO 2 retrievals in China: quantification and attribution Nian Bie, Liping Lei, ZhaoCheng Zeng, Bofeng Cai, Shaoyuan Yang, Zhonghua He, Changjiang Wu, and Ray Nassar Atmos. Meas. Tech., 11, 1251-1272, https://doi.org/10.5194/amt-11-1251-2018, 2018 The results imply that XCO 2 from satellite observations could be reliably applied in the assessment of atmospheric CO 2 enhancements induced by anthropogenic CO 2 emissions. The large inconsistency among different algorithms presented in western deserts with a high albedo and dust aerosols demonstrates that further improvement is still necessary in such regions, even though many algorithms have endeavored to minimize the effects of aerosols and albedo.
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    Publication Date: 2018-03-06
    Description: Evaluation of linear regression techniques for atmospheric applications: the importance of appropriate weighting Cheng Wu and Jian Zhen Yu Atmos. Meas. Tech., 11, 1233-1250, https://doi.org/10.5194/amt-11-1233-2018, 2018 A new data generation scheme that employs the Mersenne twister (MT) pseudorandom number generator is proposed to conduct benchmark tests on a variety of linear regression techniques. With an appropriate weighting, Deming regression (DR), weighted ODR (WODR), and York regression (YR) are recommended for atmospheric studies when both x and y data have measurement errors. An Igor-based program (Scatter Plot) is developed to facilitate the regression implementation.
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  • 62
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    Publication Date: 2018-03-06
    Description: Cloud fraction determined by thermal infrared and visible all-sky cameras Christine Aebi, Julian Gröbner, and Niklaus Kämpfer Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-68,2018 Manuscript under review for AMT (discussion: open, 0 comments) A newly developed hemispherical thermal infrared cloud camera (IRCCAM) is presented. The IRCCAM allows to detect clouds automatically during day and nighttime. The cloud fraction determined from the IRCCAM is compared with the cloud fraction determined from other instruments over a time period of two years. The IRCCAM has an agreement of ±2 oktas cloud fraction in 90 % of the data compared to other instruments. There are no significant differences between seasons or different times of day.
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    Publication Date: 2018-03-06
    Description: The Effect of Instrumental Stray Light on Brewer and Dobson Total Ozone Measurements Omid Moeini, Zahra Vaziri, C. Thomas McElroy, David W. Tarasick, Robert D. Evans, Irina Petropavlovskikh, and Keh-Harng Feng Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-2,2018 Manuscript under review for AMT (discussion: open, 0 comments) This study documents the error caused by the effect of stray light in the Brewer and Dobson total ozone measurements using a mathematical model for each instrument. The errors caused by stray light are particularly significant at high latitudes in the late winter and early spring when measurements are made at large solar zenith angles and large total ozone column. It is considerable importance if those data are to be used for trend analysis or satellite data validation.
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  • 64
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    Publication Date: 2018-03-06
    Description: Water vapour retrieval using the Precision Solar Spectroradiometer Panagiotis-Ioannis Raptis, Stelios Kazadzis, Julian Gröbner, Natalia Kouremeti, Lionel Doppler, Ralf Becker, and Constantinos Helmis Atmos. Meas. Tech., 11, 1143-1157, https://doi.org/10.5194/amt-11-1143-2018, 2018 The purpose of this work is to retrieve integrated water vapour using spectral measurements from Precision Solar Spectroradiometer (PSR). Two different approaches were developed one using single-channel direct sun irradiance measurements, and the second one integrating at a certain spectral region. The results of the spectral approach are closer to the retrievals of non-photometric techniques (GPS, microwave radiometer and radiosondes), suggesting this method provide more accurate IWV product.
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  • 65
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    Publication Date: 2018-03-06
    Description: Atmospheric QBO and ENSO indices with high vertical resolution from GNSS radio occultation temperature measurements Hallgeir Wilhelmsen, Florian Ladstädter, Barbara Scherllin-Pirscher, and Andrea K. Steiner Atmos. Meas. Tech., 11, 1333-1346, https://doi.org/10.5194/amt-11-1333-2018, 2018 Tropical atmospheric variability is often described using proxy indices of the Quasi-Biennial Oscillation and the El Niño–Southern Oscillation. We introduce new proxies derived from GNSS radio occultation (RO) satellite measurements. Using the high vertical resolution of the RO temperature fields we obtain altitude-resolved indices which can improve the description of atmospheric variability patterns and can be used in climate studies where a detailed knowledge of these patterns is required.
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    Publication Date: 2018-03-06
    Description: The SPARC water vapour assessment II: Comparison of stratospheric and lower mesospheric water vapour time series observed from satellites Farahnaz Khosrawi, Stefan Lossow, Gabriele P. Stiller, Karen H. Rosenlof, Joachim Urban, John P. Burrows, Robert P. Damadeo, Patrick Eriksson, Maya García-Comas, John C. Gille, Yasuko Kasai, Michael Kiefer, Gerald E. Nedoluha, Stefan Noël, Piera Raspollini, William G. Read, Alexei Rozanov, Christopher E. Sioris, Kaley A. Walker, and Katja Weigel Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-33,2018 Manuscript under review for AMT (discussion: open, 0 comments) Time series of stratospheric and lower mesospheric water vapour using 33 data sets were compared in the framework of the second SPARC water vapour assessment. We find that all data sets can be considered in observational and modelling studies addressing e.g. stratospheric and lower mesospheric water vapour variability and trends when data set specific characteristics (e.g. a drift) and restrictions (e.g. temporal and spatial coverage) are taken into account.
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    Publication Date: 2018-03-06
    Description: Calibration and field testing of cavity ring-down laser spectrometers measuring CH 4 , CO 2 , and δ 13 CH 4 deployed on towers in the Marcellus Shale region Natasha L. Miles, Douglas K. Martins, Scott J. Richardson, Christopher W. Rella, Caleb Arata, Thomas Lauvaux, Kenneth J. Davis, Zachary R. Barkley, Kathryn McKain, and Colm Sweeney Atmos. Meas. Tech., 11, 1273-1295, https://doi.org/10.5194/amt-11-1273-2018, 2018 Analyzers measuring methane and methane isotopic ratio were deployed at four towers in the Marcellus Shale natural gas extraction region of Pennsylvania. The methane isotopic ratio is helpful for differentiating emissions from natural gas activities from other sources (e.g., landfills). We describe the analyzer calibration. The signals observed in the study region were generally small, but the instrumental performance demonstrated here could be used in regions with stronger enhancements.
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  • 68
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    Publication Date: 2018-03-06
    Description: Comparisons of the tropospheric specific humidity from GPS radio occultations with ERA-Interim, NASA MERRA, and AIRS data Panagiotis Vergados, Anthony J. Mannucci, Chi O. Ao, Olga Verkhoglyadova, and Byron Iijima Atmos. Meas. Tech., 11, 1193-1206, https://doi.org/10.5194/amt-11-1193-2018, 2018 This study cross-compares the 10-year record of GPS radio occultation (GPS-RO) specific humidity product against independent databases (e.g., AIRS satellite, NASA/MERRA, and ERA-Interim). Our objective is to investigate the suitability of the GPS-RO humidity as a climate variable, which the science community could use in climate research. GPS-RO offers high vertical resolution, low sensitivity to clouds, and long-term stability making GPS-RO humidity a valuable complementary data set.
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    Publication Date: 2018-03-06
    Description: Reflected ray retrieval from radio occultation data using radio holographic filtering of wave fields in ray space Michael E. Gorbunov, Estel Cardellach, and Kent B. Lauritsen Atmos. Meas. Tech., 11, 1181-1191, https://doi.org/10.5194/amt-11-1181-2018, 2018 We apply linear and non-linear representations of wave fields, based on Fourier integral operators and Wigner distribution function, to the retrieval of reflected rays from radio occultation observations. We introduce a reflection index that characterizes the relative intensity of the reflected ray. A comparison of indices evaluated for a large base of events including the visual identification of reflections indicated a good agreement with our definition of reflection index.
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    Publication Date: 2018-03-06
    Description: Information content analysis: the potential for methane isotopologue retrieval from GOSAT-2 Edward Malina, Yukio Yoshida, Tsuneo Matsunaga, and Jan-Peter Muller Atmos. Meas. Tech., 11, 1159-1179, https://doi.org/10.5194/amt-11-1159-2018, 2018 We present an assessment of the predicted information content and retrieval errors for 13 CH 4 retrieval from the planned GOSAT-2 satellite, assuming a wide range of land surface conditions. Retrieval of this quantity may allow for estimation of methane source types (e.g. biological or non-biological) based on the δ 13 C metric. We conclude that GOSAT-2 can be used for this purpose (to an accuracy of 10 ‰) assuming sufficient spatial (regional) and temporal (at least monthly) averaging.
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    Publication Date: 2018-03-06
    Description: Potential of INSAT-3D Sounder Derived Total Precipitable Water Product for Weather Forecast Shailesh Parihar, Ashim Kumar Mitra, and Rajiv Bhatla Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-8,2018 Manuscript under review for AMT (discussion: open, 0 comments) Current work is based on operational work carried out at IMD, New Delhi using INSAT-3D satellite derived sounder product TPW for the weather events such as rainfall and thunderstorm. The INSAT-3D TPW is being used by forecasters as well as many user community from last 2 years. This work is mainly bring out the in-depth validation with in-situ ground measurement data as well as GNSS system for its suitability in weather prediction. This paper can be utilized operationally for weather purpose.
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  • 72
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    Publication Date: 2018-03-06
    Description: Evaluation of linear regression techniques for atmospheric applications: the importance of appropriate weighting Cheng Wu and Jian Zhen Yu Atmos. Meas. Tech., 11, 1233-1250, https://doi.org/10.5194/amt-11-1233-2018, 2018 A new data generation scheme that employs the Mersenne twister (MT) pseudorandom number generator is proposed to conduct benchmark tests on a variety of linear regression techniques. With an appropriate weighting, Deming regression (DR), weighted ODR (WODR), and York regression (YR) are recommended for atmospheric studies when both x and y data have measurement errors. An Igor-based program (Scatter Plot) is developed to facilitate the regression implementation.
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  • 73
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    Publication Date: 2018-03-06
    Description: A full-mission data set of H 2 O and HDO columns from SCIAMACHY 2.3 μm reflectance measurements Andreas Schneider, Tobias Borsdorff, Joost aan de Brugh, Haili Hu, and Jochen Landgraf Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2017-489,2018 Manuscript under review for AMT (discussion: open, 0 comments) A new data set of vertical column densities of the water vapour isotopologues H 2 O and HDO retrieved from shortwave infrared measurements (2339 nm to 2383 nm) by the SCIAMACHY satellite instrument for the whole mission period from 2003 to 2012 is presented. The data are validated against ground-based Fourier transform infrared measurements. High-altitude stations observe different air columns, thus in this case collocated scenes with clouds around station height are needed for agreement.
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  • 74
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    Publication Date: 2018-03-06
    Description: Modelling biogeochemical processes in sediments from the north-western Adriatic Sea: response to enhanced particulate organic carbon fluxes Daniele Brigolin, Christophe Rabouille, Bruno Bombled, Silvia Colla, Salvatrice Vizzini, Roberto Pastres, and Fabio Pranovi Biogeosciences, 15, 1347-1366, https://doi.org/10.5194/bg-15-1347-2018, 2018 We present the result of a study carried out in the north-western Adriatic Sea by combining two different types of models with field sampling. A mussel farm was taken as a local source of perturbation to the natural flux of particulate organic carbon to the sediment. Differences in fluxes were primarily associated with mussel physiological conditions. Although restricted, these changes in particulate organic carbon fluxes induced visible effects on sediment biogeochemistry.
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    Publication Date: 2018-03-06
    Description: The pyrogeography of eastern boreal Canada from 1901 to 2012 simulated with the LPJ-LMfire model Emeline Chaste, Martin P. Girardin, Jed O. Kaplan, Jeanne Portier, Yves Bergeron, and Christelle Hély Biogeosciences, 15, 1273-1292, https://doi.org/10.5194/bg-15-1273-2018, 2018 A vegetation model was used to reconstruct fire activity from 1901 to 2012 in relation to changes in lightning ignition, climate, and vegetation in eastern Canada's boreal forest. The model correctly simulated the history of fire activity. The results showed that fire activity is ignition limited but is also greatly affected by both climate and vegetation. This research aims to develop a vegetation model that could be used to predict the future impacts of climate changes on fire activity.
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    Publication Date: 2018-03-06
    Description: Manganese incorporation in living (stained) benthic foraminiferal shells: A bathymetric and in-sediment study in the Gulf of Lions (NW Mediterranean) Shauna Ní Fhlaithearta, Christophe Fontanier, Frans Jorissen, Aurélia Mouret, Adriana Dueñas-Bohórquez, Pierre Anschutz, Mattias B. Fricker, Detlef Günther, Gert J. de Lange, and Gert-Jan Reichart Biogeosciences Discuss., https//doi.org/10.5194/bg-2018-42,2018 Manuscript under review for BG (discussion: open, 0 comments) This study looks to how foraminifera interact with their geochemical environment in the seabed. We focus on the incorporation of the trace metal manganese (Mn), with the aim of developing a tool to reconstruct past pore water profiles. Manganese concentrations in foraminifera are investigated relative to their ecological preferences and geochemical environment. This study demonstrates that Mn in foraminiferal tests is a promising tool to reconstruct oxygen conditions in the seabed.
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    Publication Date: 2018-03-06
    Description: Plant responses to volcanically-elevated CO 2 in two Costa Rican forests Robert R. Bogue, Florian M. Schwandner, Joshua B. Fisher, Ryan Pavlick, Troy S. Magney, Caroline A. Famiglietti, Kerry Cawse-Nicholson, Vineet Yadav, Justin P. Linick, Gretchen B. North, and Eliecer Duarte Biogeosciences Discuss., https//doi.org/10.5194/bg-2018-100,2018 Manuscript under review for BG (discussion: open, 0 comments) We studied trees growing on the outer areas of two volcanoes in Costa Rica to examine the effects of volcanic CO 2 emissions on tree characteristics. We measured two tree species and found that they were comprised of carbon from the volcanic CO 2 . Volcanic CO 2 emissions may also have measurable impacts on leaf function measurements. Our results have implications for reconstructing volcanic degassing histories at previously unmonitored volcanoes and studying biological impacts of elevated CO 2 .
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    Publication Date: 2018-03-06
    Description: Technical Note: Rapid image-based field methods improve the quantification of termite mound structures and greenhouse-gas fluxes Philipp A. Nauer, Eleonora Chiri, David de Souza, Lindsay B. Hutley, and Stefan K. Arndt Biogeosciences Discuss., https//doi.org/10.5194/bg-2018-43,2018 Manuscript under review for BG (discussion: open, 0 comments) Termites provide important functions in tropical ecosystems, but the complex structure of their mounds impede an accurate quantitative description. We present two novel field methods, based on photogrammetry and image analysis, to quantify the volume, surface area and porosities of termite mounds. The methods are accurate, rapid to apply and superior to established methods, therefore greatly improve biogeochemical rate estimates such as greenhouse-gas fluxes from termite mounds.
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    Publication Date: 2018-03-06
    Description: A niche comparison of Emiliania huxleyi and Gephyrocapsa oceanica and potential effects of climate change Natasha A. Gafar and Kai G. Schulz Biogeosciences Discuss., https//doi.org/10.5194/bg-2018-88,2018 Manuscript under review for BG (discussion: open, 1 comment) Emiliania huxleyi and Gephyrocapsa oceanica are the most prolific calcifying phytoplankton in todays oceans. Here we compare their sensitivity to combined anthropogenic stressors of temperature, light and CO 2 . For the future we project a niche contraction for G. oceanica . Furthermore, there was good correlation of our new metric, the CaCO 3 production potential, with satellite derived concentrations in the modern ocean, indicating means of assessing overall coccolithophorid success in the future.
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    Publication Date: 2018-03-06
    Description: Coral reef carbonate budgets and ecological drivers in the naturally high temperature and high total alkalinity environment of the Red Sea Anna Roik, Till Roethig, Claudia Pogoreutz, Vincent Saderne, and Christian R. Voolstra Biogeosciences Discuss., https//doi.org/10.5194/bg-2018-57,2018 Manuscript under review for BG (discussion: open, 0 comments) In this study we collected in situ accretion/erosion rates and abiotic/biotic variables to estimate carbonate budgets and ecological drivers of coral reef growth in the central Red Sea. Our data suggest that reef growth is comparable to estimates of other regions, but the erosive forces in the Red Sea are not as pronounced. Comparison with recent data suggest that Red Sea reef growth might not have decreased over the past decades, despite warming, calling for more detailed investigations.
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    Publication Date: 2018-03-06
    Description: Catchment tracers reveal discharge, recharge and sources of groundwater-borne pollutants in a novel lake modelling approach Emil Kristensen, Mikkel Madsen-Østerbye, Philippe Massicotte, Ole Pedersen, Stiig Markager, and Theis Kragh Biogeosciences, 15, 1203-1216, https://doi.org/10.5194/bg-15-1203-2018, 2018 We propose a novel modelling approach enabling swift hydrological surveys based on multiple conservative and non-conservative tracers to estimate water retention time, groundwater discharge sites, fractions of water originating from the discharge sites, groundwater recharge sites and sites that are especially important in regard to groundwater recharge. Thus we provide a whole lake hydrological survey while pinpointing sources of pollutants like colored dissolved organic matter and nutrients.
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    Copernicus
    Publication Date: 2018-03-06
    Description: Eolian dust dispersal patterns since the last glacial period in eastern Central Asia: insights from a loess-paleosol sequence in the Ili Basin Yue Li, Yougui Song, Kathryn E. Fitzsimmons, Hong Chang, Rustam Orozbaev, and Xinxin Li Clim. Past, 14, 271-286, https://doi.org/10.5194/cp-14-271-2018, 2018 This paper finds a close tie between loess magnetic susceptibility and wind strength in the Ili Basin, eastern Central Asia, and identifies three distinct aerodynamic environments with end-member modeling analysis of grain size. The Siberian High is the dominant influence on wind dynamics, resulting in loess deposition, and acts as a teleconnection between the climatic systems of the North Atlantic and East Asia in the high northern latitudes, but not for the mid-latitude westerlies.
    Print ISSN: 1814-9324
    Electronic ISSN: 1814-9332
    Topics: Geosciences
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  • 83
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    Copernicus
    Publication Date: 2018-03-06
    Description: Climate impact on the development of Pre-Classic Maya civilization Kees Nooren, Wim Z. Hoek, Brian J. Dermody, Didier Galop, Sarah Metcalfe, Gerald Islebe, and Hans Middelkoop Clim. Past Discuss., https//doi.org/10.5194/cp-2018-15,2018 Manuscript under review for CP (discussion: open, 0 comments) We present two new palaeoclimatic records for the Central Maya Lowlands, adding valuable new insights into the impact of climate change on the development of Maya civilization. Lake Tuspan's diatom record is indicative of precipitation changes at a local scale, while a beach ridge elevation record from world’s largest late Holocene beach ridge plain provides a regional picture.
    Print ISSN: 1814-9324
    Electronic ISSN: 1814-9332
    Topics: Geosciences
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  • 84
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    Copernicus
    Publication Date: 2018-03-06
    Description: Astronomical tunings of the Oligocene–Miocene transition from Pacific Ocean Site U1334 and implications for the carbon cycle Helen M. Beddow, Diederik Liebrand, Douglas S. Wilson, Frits J. Hilgen, Appy Sluijs, Bridget S. Wade, and Lucas J. Lourens Clim. Past, 14, 255-270, https://doi.org/10.5194/cp-14-255-2018, 2018 We present two astronomy-based timescales for climate records from the Pacific Ocean. These records range from 24 to 22 million years ago, a time period when Earth was warmer than today and the only land ice was located on Antarctica. We use tectonic plate-pair spreading rates to test the two timescales, which shows that the carbonate record yields the best timescale. In turn, this implies that Earth’s climate system and carbon cycle responded slowly to changes in incoming solar radiation.
    Print ISSN: 1814-9324
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  • 85
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    Copernicus
    Publication Date: 2018-03-06
    Description: Climate information preserved in seasonal water isotope at NEEM: relationships with temperature, circulation and sea ice Minjie Zheng, Jesper Sjolte, Florian Adolphi, Bo Møllesøe Vinther, Hans Christian Steen-Larsen, Trevor James Popp, and Raimund Muscheler Clim. Past Discuss., https//doi.org/10.5194/cp-2018-8,2018 Manuscript under review for CP (discussion: open, 0 comments) Analyzing seasonally resolved δ 18 O ice core data can aid the interpretation of the climate information in ice cores, providing also insights into factors governing the δ 18 O signal that cannot be deciphered by investigating the annual δ 18 O data only. However, the seasonal isotope signal has not yet to be investigated in northern Greenland, e.g. at the NEEM (North Greenland Eemian Ice Drilling) ice core drill site. Here we analyze seasonally resolved δ 18 O data from four shallow NEEM ice cores covering the last 150 years. Based on correlation analysis with observed temperature, we attribute about 70 % and 30 % of annual accumulation to summer and winter respectively. The NEEM summer δ 18 O signal correlates strongly with summer western Greenland coastal temperature and with the first principal component (PC1) of summer δ 18 O from multiple seasonally resolved ice cores from central/southern Greenland. However, there are no significant correlations between NEEM winter δ 18 O data and western Greenland coastal winter temperature, or southern/central Greenland winter δ 18 O PC1. The stronger correlation with temperature during summer and the dominance of summer precipitation skew the annual δ 18 O signal in NEEM. The strong footprint of temperature in NEEM summer δ 18 O record also suggests that the summer δ 18 O record, rather than the winter δ 18 O record, is a better temperature proxy at the NEEM site. Despite dominant signal of North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO) in the central-southern ice cores data, both NAO and AMO exert weak influences on NEEM seasonal δ 18 O variations. The NEEM seasonal δ 18 O is found to be highly correlated with Baffin Bay sea ice concentration (SIC) in satellite observation period (1979–2004), suggesting a connection of the sea ice extent with δ 18 O at NEEM. NEEM winter δ 18 O significantly correlates with SIC even for the period prior to satellite observation (1901–1978). The NEEM winter δ 18 O may reflect sea ice variations of Baffin Bay rather than temperature itself. This study shows that seasonally resolved δ 18 O records, especially for sites with seasonal precipitation bias such as NEEM, provide a better understanding of how changing air temperature and circulation patterns are associated with the variability of the δ 18 O records.
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  • 86
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    Copernicus
    Publication Date: 2018-03-06
    Description: Response of the carbon cycle in an intermediate complexity model to the different climate configurations of the last nine interglacials Nathaelle Bouttes, Didier Swingedouw, Didier M. Roche, Maria F. Sanchez-Goni, and Xavier Crosta Clim. Past, 14, 239-253, https://doi.org/10.5194/cp-14-239-2018, 2018 Atmospheric CO 2 is key for climate change. CO 2 is lower during the oldest warm period of the last million years, the interglacials, than during the most recent ones (since 430 000 years ago). This difference has not been explained yet, but could be due to changes of ocean circulation. We test this hypothesis and the role of vegetation and ice sheets using an intermediate complexity model. We show that only small changes of CO 2 can be obtained, underlying missing feedbacks or mechanisms.
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  • 87
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    Copernicus