bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Investigation of Parameters, Influencing Velocity Fields during Beer Fermentation
Authors: Meironke Heiko , Böttcher Kai
Published: December 2013

In the course of the research aiming on the optimisation of beer fermentation, a large number of fermentations have been performed under various boundary conditions. We carried out different measurements, including temperature and velocity investigations. Due to turbidity, the latter cannot be performed easily by using common techniques like laser Doppler anemometry or particle image velocimetry. Therefore the ultrasound Doppler velocimetry got utilised. It permits measurements in opaque fluids and provides velocity fields for any time during the fermentation.
Organic Rankine Cycle as Bottoming Cycle to a Combined Brayton and Clausius - Rankine Cycle
Authors: Mikielewicz Dariusz , Wajs Jan , Żmuda Elżbieta
Published: December 2013

A preliminary evaluation has been made of a possibility of bottoming of a conventional Brayton cycle cooperating with the CHP power plant with the organic Rankine cycle installation. Such solution contributes to the possibility of annual operation of that power plant, except of operation only in periods when there is a demand for the heat. Additional benefit would be the fact that an optimized backpressure steam cycle has the advantage of a smaller pressure ratio and therefore a less complex turbine design with smaller final diameter. In addition, a lower superheating temperature is required compared to a condensing steam cycle with the same evaporation pressure. Bottoming ORCs have previously been considered by Chacartegui et al. for combined cycle power plants [ Their main conclusion was that challenges are for the development of this technology in medium and large scale power generation are the development of reliable axial vapour turbines for organic fluids. Another study was made by Angelino et al. to improve the performance of steam power stations [. This paper presents an enhanced approach, as it will be considered here that the ORC installation could be extra-heated with the bleed steam, a concept presented by the authors in [. In such way the efficiency of the bottoming cycle can be increased and an amount of electricity generated increases. A thermodynamic analysis and a comparative study of the cycle efficiency for a simplified steam cycle cooperating with ORC cycle will be presented. The most commonly used organic fluids will be considered, namely R245fa, R134a, toluene, and 2 silicone oils (MM and MDM). Working fluid selection and its application area is being discussed based on fluid properties. The thermal efficiency is mainly determined by the temperature level of the heat source and the condenser conditions. The influence of several process parameters such as turbine inlet and condenser temperature, turbine isentropic efficiency, vapour quality and pressure, use of a regenerator (ORC) will be presented. Finally, some general and economic considerations related to the choice between a steam cycle and ORC are discussed.
Liquid Metal Embrittlement of Steel with a Coating Obtained by Batch Hot Dip Method in a Zn + 2% Sn Bath
Authors: Mendala Jacek , Liberski Piotr
Published: December 2013

The article presents investigation of steel subjected to external stress during hot-dip metallization. The results of experimental investigations of the LME phenomenon, reasons of its formation and influence of different parameters are described. Samples made of C70D steel subjected to various loads inducing tensile stress (400-800 MPa) during hot dip metallization ina zinc bath with 2% tin addition were investigated. The processes of hot dip metallization were carried out at 450°C temperature and immersion time of 180 s. It can be observed that the stress value can affect the behaviour of metal during the hot dip metallization process. Coated samples were analysed on a light microscope to specify the possibility of the occurrence of LME. These studies provided the basis for the selection of samples and areas for further quantitative andqualitative analysis on a scanning electron microscope (SEM) with a microanalysis system. The analysis of cracks in three microareas revealed that the tin content in the front of a fracture is twice as big as it is in other measuring points. It may be related to crack propagation due to the phenomenon of LME, by the accumulation of the initiating element atoms and those propagating the fracture.
Influence of the Ion Nitriding Process on the Electrochemical Properties of X39Cr13 Steel Used for Surgical Instruments
Authors: Basiaga Marcin , Przondziono Joanna
Published: December 2013

The main aim of this work was to determine the effect of nitriding process on the electrochemical properties of martensitic steel X39Cr13 used for surgical instruments treatments. The research was conducted on the samples of diameter d = 14 mm made of X39Cr13 martensitic steel in the annealed condition. The samples were subjected to heat-treatment: hardening and tempering processes. The way of surface preparation of the samples contained mechanical processing: barrel finishing, chemical passivation and nitriding using fluorescent methods. The nitriding process was carried out in an apparatus for machining a cooled anode glow type JON-600. Nitriding process was carried out at a temperature T = 470 °C. To evaluate the electrochemical properties the pitting corrosion resistance were studied. The corrosion resistance tests of samples were carried out by means of potentiodynamic method (registering anodic polarization curves). The measurements were conducted in physiological Tyrodes solution. On the basis of the results it was affirmed diverse corrosion resistance of the samples for different variants of the surface preparation. The highest corrosion resistance was observed for the barrel finished and nitriding process of the samples. The research revealed that the suggested variants of surface treatment influence the corrosion resistance of the X39Cr13 steel intended for surgical tools.
Kinetics of Growth and Structure of Coatings Obtained on Sandelin Steels in the High-Temperature Galvanizing Process
Authors: Kania Henryk
Published: December 2013

In the paper the author presents the results of tests defining the characteristics of behaviour of Sandelin steel in the high-temperature galvanizing process. The growth kinetics of hot-dip zinc coatings on the substrate of 0.05% Si steel in the temperature range of 540-580°C has been established. The structure of the coatings and their phase composition have been developed and the chemical composition of structural components of the coating has be defined. It has been determined that the coating is composed of a compact layer δ1 and an area of a two-phase mixture of δ1 and Zn. The conducted tests confirmed the presence of phase Γ1 , which does not form a continuous layer but it forms individual precipitates which are irregular in shape. The growth kinetics of the coating indicates that an increase in temperature causes a decrease in the coating thickness, which might prove that dissolving processes prevailed over the processes of diffuse coating growth.
Kinetics of Corrosion Processes of Alloy on the Intermetallic Phase Matrix FeAl in High Temperature in Air Atmosphere
Authors: Cebulski Janusz , Lalik Stanisław
Published: December 2013

The aim of this paper was to determine the resistance to high-temperature corrosion in atmosphere of air for alloy Fe-40Al-5Cr-0.2Ti-0.2B. Corrosion tests were conducted in temperatures from 600 to 900°C in time from 2 to 64 hours. Conducted tests have shown a slight increase of weight of samples in periods of time which followed. Increase of weight is connected with corrosion products in the form of passive oxides which form on the surface of the alloy. Kinetics of corrosion processes has parabolic course in tested temperature range which proves the formation of passive layers of corrosion products on the surface of samples. Heat resistance of the alloy on intermetallic phase matrix FeAl brings about potential possibilities to apply this alloy as a material meant for work in elevated and high temperatures in the environment which includes oxygen.
Influence of Corrosion in "Acid Rain" on the Structure of Surface Layer of the ZnAl22Cu3 Alloy
Authors: Michalik Rafał
Published: December 2013

The effect of corrosion in an "acid rain" (pH = 3.5) environment on the structure of the surface layer of the ZnAl22Cu3 alloy are presented in this study. Base alloy, alloy with silicon and alloy with silicon and rare earth elements were tested. The scope of the examination included potentiostatic tests in acid rain and studies of structure of surface layer of samples after corrosion tests. The studies have shown, that corrosion processes initially run quickly which leads to reduction of zinc in the surface layer and enriching in aluminum and copper so that the corrosion rate decreases. The presence of the silicon precipitates does not decrease the corrosion resistance of the ZnAl22Cu3 alloy in acid rain environment. The addition of rare earth elements improves the corrosion resistance of the ZnAl22Cu3 alloy in acid rain environment.
Application of Incremental Metal Forming for Production of Aircraft Integral Panels
Authors: Tkocz Marek , Grosman Franciszek
Published: December 2013

The principle and the potential of an incremental bulk metal forming method is presented in the paper. It can be used for manufacturing of the specific aircraft integral panels in a form of ribbed parts with high surface/thickness ratio. A unique laboratory device has been developed to investigate the effect of process parameters on the material flow and the press load. It utilizes tooling consisting of working rolls, a die and a punch that is divided into a number of segments. The results of preliminary numerical simulations proved that the presented forming method offers significant advantages in comparison with conventional forging.
Influence of Heat Treatment on the Hardness of ZnAl22Cu3 Alloy
Authors: Michalik Rafał , Tomaszewska Agnieszka
Published: December 2013

The effect of heat treatment on the structure and hardness of the ZnAl22Cu3 alloy is presented in the paper. ZnAl22 and ZnAl22Cu3 alloys were tested. The scope of the examination included dilatometry, structural and hardness tests. Very interesting is the effect of the transformation, occurring at lower temperatures on the structure and hardness of the alloy. There are found, that soaking at 185°C causes a decrease in the hardness of the ZnAl22Cu3 alloy. Observed ZnAl22Cu3 alloy hardness decrease is related to the disappearance of zinc-rich dendrites and the transition of zinc to a eutectoid mixture.
The Correlation between the Surface Geometry of Tested Materials and the Shape of Lubricant Drop
Authors: Dolata Anna J. , Wieczorek Jakub
Published: December 2013

In manufacturing of air compressors, piston engines and guides, lubricants are used to result in formation of a continuous oil film that separates the friction surfaces. The continuity of this film within the entire operating range of the friction pair, from starting to steady state, is the guarantee of proper operation. The surface geometry of friction elements plays significant role in maintaining continuity of the oil film. The widely used method for obtaining proper surface condition of the structural components of piston systems is the honing process. This method consists of shaping the microgeometry of the surface of friction pair elements by material removal processing methods (turning, grinding, laser processing) to prevent rapid spreading of lubricant, and thus to prevent breaking of the oil film. In case of Al-MMCs using for manufacturing the parts of machines working under friction with lubrication conditions the shaping of their working surface by honing is limited by the machining efficiency. The investigations on surface geometry of elements made of composites including ceramic reinforcement revealed that presence of reinforcement particles on the working surface bring the changes which can be used for shaping the correct oil film. The investigations presented in this article can be used for evaluation of lubricant propagation process on the composite material surface.
Regularity of expanding front and its application to solidification/melting in undercooled liquid/superheated solid
Authors: Chen Xinfu , Jiang Huiqiang
Published: December 2013

This article proves that fronts of expanding domains with Hölder continuous speeds are contained in finite unions of Lipschitz graphs. As an application, the global in time existence of a solution to a free boundary problem modelling solidification in undercooled liquid or liquidation in superheated solid is established; here the propagation speed of the liquid/solid interface is assumed to be a known positive smooth function of the temperature, known as a kinetic undercooling/superheating effect.
Traveling waves from the arclength parameterization: Vortex sheets with surface tension
Authors: Akers Benjamin , Ambrose David M. , Wright J. Douglas
Published: December 2013

We study traveling waves for the vortex sheet with surface tension. We use the angle-arclength description of the interface rather than Cartesian coordinates, and we utilize an arclength parameterization as well. In this setting, we make a new formulation of the traveling wave ansatz. For this problem, it should be possible for traveling waves to overturn, and notably, our formulation does allow for waves with multi-valued height. We prove that there exist traveling vortex sheets with surface tension bifurcating from equilibrium. We compute these waves by means of a quasi-Newton iteration in Fourier space; we find continua of traveling waves bifurcating from equilibrium and extending to include overturning waves, for a variety of values of the mean vortex sheet strength.
On the interactions between a solid body and a compressible inviscid fluid
Authors: Borsche Raul , Colombo Rinaldo M. , Garavello Mauro
Published: December 2013

This paper presents a model describing the interaction between a solid body and a compressible inviscid fluid in a pipe. The resulting system consists in a 1D hyperbolic balance law coupled with an ordinary differential equation and is proved to be well posed. Simple explicit solutions and numerical integrations show qualitative features of this model. In particular, we consider a ball falling in a vertical tube closed at the bottom. This system results in the ball bouncing on the shocks reflected between the ball and the bottom.
Optimizing CALIPSO Saharan dust retrievals
Authors: Amiridis V. , Wandinger U. , Marinou E. , Giannakaki E. , Tsekeri A. , Basart S. , Kazadzis S. , Gkikas A. , Taylor M. , Baldasano J. , Ansmann A.
Published: December 2013

Abstract. We demonstrate improvements in CALIPSO (Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations) dust extinction retrievals over northern Africa and Europe when corrections are applied regarding the Saharan dust lidar ratio assumption, the separation of the dust portion in detected dust mixtures, and the averaging scheme introduced in the Level 3 CALIPSO product. First, a universal, spatially constant lidar ratio of 58 sr instead of 40 sr is applied to individual Level 2 dust-related backscatter products. The resulting aerosol optical depths show an improvement compared with synchronous and collocated AERONET (Aerosol Robotic Network) measurements. An absolute bias of the order of −0.03 has been found, improving on the statistically significant biases of the order of −0.10 reported in the literature for the original CALIPSO product. When compared with the MODIS (Moderate-Resolution Imaging Spectroradiometer) collocated aerosol optical depth (AOD) product, the CALIPSO negative bias is even less for the lidar ratio of 58 sr. After introducing the new lidar ratio for the domain studied, we examine potential improvements to the climatological CALIPSO Level 3 extinction product: (1) by introducing a new methodology for the calculation of pure dust extinction from dust mixtures and (2) by applying an averaging scheme that includes zero extinction values for the nondust aerosol types detected. The scheme is applied at a horizontal spatial resolution of 1° × 1° for ease of comparison with the instantaneous and collocated dust extinction profiles simulated by the BSC-DREAM8b dust model. Comparisons show that the extinction profiles retrieved with the proposed methodology reproduce the well-known model biases per subregion examined. The very good agreement of the proposed CALIPSO extinction product with respect to AERONET, MODIS and the BSC-DREAM8b dust model makes this dataset an ideal candidate for the provision of an accurate and robust multiyear dust climatology over northern Africa and Europe.
Estimates of turbulent diffusivities and energy dissipation rates from satellite measurements of spectra of stratospheric refractivity perturbations
Authors: Gavrilov N. M.
Published: December 2013

Abstract. Approaches for estimations of effective turbulent diffusion and energetic parameters from characteristics of anisotropic and isotropic spectra of perturbations of atmospheric refractivity, density and temperature are developed. The approaches are applied to the data obtained with the GOMOS instrument for measurements of stellar scintillations on-board the Envisat satellite to estimate turbulent Thorpe scales, LT, diffusivities, K, and energy dissipation rates, ϵ, in the stratosphere. At low latitudes, effective values are LT ~ 1–1.1 m, ϵ ~ (1.8–2.4) × 10−5 W kg−1, and K ~ (1.2–1.6) × 10−2 m2 s−1 at altitudes of 30–45 km in September–November 2004, depending on different assumed values of parameters of anisotropic and isotropic spectra. Respective standard deviations of individual values, including all kinds of variability, are δLT ~ 0.6–0.7 m, δϵ ~ (2.3–3.5) × 10−2 W kg−1, and δK ~ (1.7–2.6) × 10−2 m2 s−1. These values correspond to high-resolution balloon measurements of turbulent characteristics in the stratosphere, and to previous satellite stellar scintillation measurements. Distributions of turbulent characteristics at altitudes of 30–45 km in low latitudes have maxima at longitudes corresponding to regions of increased gravity wave dissipation over locations of stronger convection. Correlations between parameters of anisotropic and isotropic spectra are evaluated.
The regime of intense desert dust episodes in the Mediterranean based on contemporary satellite observations and ground measurements
Authors: Gkikas A. , Hatzianastassiou N. , Mihalopoulos N. , Katsoulis V. , Kazadzis S. , Pey J. , Querol X. , Torres O.
Published: December 2013

Abstract. The regime of intense desert dust (DD) episodes over the broader Mediterranean Basin is studied for the period 2000–2007 at a complete spatial coverage. An objective and dynamic algorithm has been set up which uses daily measurements of various aerosol optical properties taken by different satellite databases, enabling the identification of DD episodes and their classification into strong and extreme ones. The algorithm's performance was tested against surface-based (in situ) particulate matter (PM) and (columnar) sun-photometric AERONET (AErosol RObotic NETwork) measurements from stations distributed across the Mediterranean. The comparisons have shown the reasonable ability of the algorithm to detect the DD episodes taking place within the study region. The largest disagreements with PM data were found in the western Mediterranean in summer, when African dust transport has a great vertical extent that cannot be satisfactorily captured by surface measurements. According to our results, DD episodes in the Mediterranean Basin are quite frequent (up to 11.4 episodes yr−1), while there is a significant spatial and temporal variability in their frequency of occurrence and their intensity. Strong episodes occur more frequently in the western Mediterranean Basin, whilst extreme ones appear more frequently over central Mediterranean Sea areas. Apart from this longitudinal variation, there is a predominant latitudinal variability in both frequency and intensity, with decreasing values from south to north. A significant seasonal variation was also found for the frequency of DD episodes, with both strong and extreme episodes being more frequent during summer in the western Mediterranean Basin, but during spring in its central and eastern parts. In most cases (> 85%) the Mediterranean dust episodes last a bit longer than a day on average, although their duration can reach six days for strong episodes and four days for extreme episodes. A noticeable year-to-year variability was also found, especially for the frequency of the episodes.
Advances in understanding and parameterization of small-scale physical processes in the marine Arctic climate system: a review
Authors: Vihma T. , Pirazzini R. , Renfrew I. A. , Sedlar J. , Tjernström M. , Nygård T. , Fer I. , Lüpkes C. , Notz D. , Weiss J. , Marsan D. , Cheng B. , Birnbaum G. , Gerland S. , Chechin D. , Gascard J. C.
Published: December 2013

Abstract. The Arctic climate system includes numerous highly interactive small-scale physical processes in the atmosphere, sea ice, and ocean. During and since the International Polar Year 2007–2008, significant advances have been made in understanding these processes. Here these advances are reviewed, synthesized and discussed. In atmospheric physics, the primary advances have been in cloud physics, radiative transfer, mesoscale cyclones, coastal and fjordic processes, as well as in boundary-layer processes and surface fluxes. In sea ice and its snow cover, advances have been made in understanding of the surface albedo and its relationships with snow properties, the internal structure of sea ice, the heat and salt transfer in ice, the formation of super-imposed ice and snow ice, and the small-scale dynamics of sea ice. In the ocean, significant advances have been related to exchange processes at the ice–ocean interface, diapycnal mixing, tidal currents and diurnal resonance. Despite this recent progress, some of these small-scale physical processes are still not sufficiently understood: these include wave-turbulence interactions in the atmosphere and ocean, the exchange of heat and salt at the ice–ocean interface, and the mechanical weakening of sea ice. Many other processes are reasonably well understood as stand-alone processes but challenge is to understand their interactions with, and impacts and feedbacks on, other processes. Uncertainty in the parameterization of small-scale processes continues to be among the largest challenges facing climate modeling, and nowhere is this more true than in the Arctic. Further improvements in parameterization require new year-round field campaigns on the Arctic sea ice, closely combined with satellite remote sensing studies and numerical model experiments.
On the variability of atmospheric 222Rn activity concentrations measured at Neumayer, coastal Antarctica
Authors: Weller R. , Levin I. , Schmithüsen D. , Nachbar M. , Asseng J. , Wagenbach D.
Published: December 2013

Abstract. We report on continuously measured 222Rn activity in near surface air at Neumayer Station in the period 1995 through 2011. This 17 yr record showed no long-term trend and has overall mean ± standard deviation of (0.019 ± 0.012) Bq m−3. A distinct and persistent seasonality could be distinguished with maximum values of (0.028 ± 0.013) Bq m−3 from January through March and minimum values of (0.015 ± 0.009) Bq m−3 from May through October. Elevated 222Rn activity concentrations were typically associated with air mass transport from the Antarctic Plateau. Our results do not support a relation between enhanced 222Rn activity concentrations at Neumayer and cyclonic activity or long-range transport from South America. The impact of oceanic 222Rn emissions could not be properly assessed but we tentatively identified regional SIE variability as a significant driver of the annual 222Rn cycle.
The response of super pressure balloons to gravity wave motions
Authors: Vincent R. A. , Hertzog A.
Published: December 2013

Abstract. Super pressure balloons (SPB), which float on constant density (isopycnic) surfaces, provide a unique way of measuring the properties of atmospheric gravity waves (GW) as a function of wave intrinsic frequency. Here we devise a quasi-analytic method of investigating the SPB response to GW motions. It is shown that the results agree well with more rigorous numerical simulations of balloon motions and provide a better understanding of the response of SPB to GW, especially at high frequencies. The methodology is applied to ascertain the accuracy of GW studies using 12 m diameter SPB deployed in the 2010 Concordiasi campaign in the Antarctic. In comparison with the situation in earlier campaigns, the vertical displacements of the SPB were measured directly using GPS. It is shown using a large number of Monte-Carlo type simulations with realistic instrumental noise that important wave parameters, such as momentum flux, phase speed and wavelengths, can be retrieved with good accuracy from SPB observations for intrinsic wave periods greater than about 10 min. The noise floor for momentum flux is estimated to be about 10−4 mPa.
Simulating boreal forest carbon dynamics after stand-replacing fire disturbance: insights from a global process-based vegetation model
Authors: Yue C. , Ciais P. , Luyssaert S. , Cadule P. , Harden J. , Randerson J. , Bellassen V. , Wang T. , Piao S. L. , Poulter B. , Viovy N.
Published: December 2013

Abstract. Stand-replacing fires are the dominant fire type in North American boreal forests. They leave a historical legacy of a mosaic landscape of different aged forest cohorts. This forest age dynamics must be included in vegetation models to accurately quantify the role of fire in the historical and current regional forest carbon balance. The present study adapted the global process-based vegetation model ORCHIDEE to simulate the CO2 emissions from boreal forest fire and the subsequent recovery after a stand-replacing fire; the model represents postfire new cohort establishment, forest stand structure and the self-thinning process. Simulation results are evaluated against observations of three clusters of postfire forest chronosequences in Canada and Alaska. The variables evaluated include: fire carbon emissions, CO2 fluxes (gross primary production, total ecosystem respiration and net ecosystem exchange), leaf area index, and biometric measurements (aboveground biomass carbon, forest floor carbon, woody debris carbon, stand individual density, stand basal area, and mean diameter at breast height). When forced by local climate and the atmospheric CO2 history at each chronosequence site, the model simulations generally match the observed CO2 fluxes and carbon stock data well, with model-measurement mean square root of deviation comparable with the measurement accuracy (for CO2 flux ~100 g C m−2 yr−1, for biomass carbon ~1000 g C m−2 and for soil carbon ~2000 g C m−2). We find that the current postfire forest carbon sink at the evaluation sites, as observed by chronosequence methods, is mainly due to a combination of historical CO2 increase and forest succession. Climate change and variability during this period offsets some of these expected carbon gains. The negative impacts of climate were a likely consequence of increasing water stress caused by significant temperature increases that were not matched by concurrent increases in precipitation. Our simulation results demonstrate that a global vegetation model such as ORCHIDEE is able to capture the essential ecosystem processes in fire-disturbed boreal forests and produces satisfactory results in terms of both carbon fluxes and carbon-stock evolution after fire. This makes the model suitable for regional simulations in boreal regions where fire regimes play a key role in the ecosystem carbon balance.
Seasonal and interannual variations of the nitrogen cycle in the Arabian Sea
Authors: Rixen T. , Baum A. , Gaye B. , Nagel B.
Published: December 2013

Abstract. The Arabian Sea is strongly influenced by the Asian monsoon and plays an important role as a climate archive and in the marine nitrogen cycle, because bio-available NO3− is reduced to dinitrogen gas (N2) in its mid-water oxygen minimum layer (OMZ). In order to investigate seasonal and interannual variations of the nitrogen cycle, nutrient data were obtained from the literature prior to 1993, evaluated, and compared with data measured during five expeditions in 1995 as well as a research cruise in 2007. Our results imply that the area characterized by a pronounced secondary nitrite maximum (SNM) was by 63% larger in 1995 than before. This area, referred to as the core of the denitrifying zone, shows strong seasonal and interannual variations driven by the monsoon. During the SW monsoon the SNM retreats eastwards due to the inflow of oxygen-enriched Indian Ocean Central Water (ICW) and it expands westwards during the NE monsoon because of the reversal of the current regime, which allows the propagation of denitrification signals from the Indian shelf into the open Arabian Sea. On an interannual time-scale an enhanced SW monsoon increases NO3− losses by increasing the upwelling-driven carbon export into the subsurface waters. An associate enhanced inflow of ICW increases the transport of denitrification signals from the SNM into the upwelling region and compensates NO3− losses by enhanced NO3− supply from the Indian Ocean. The latter sustains an enhanced productivity, which in turn transfers denitrification signals into the sedimentary records. On glacial interglacial time scales sea level changes affecting the inflow of ICW seem to increase variations in the accumulation of denitrification tracers in the SNM by reducing the residence time during glacial periods.
Isoprene emissions track the seasonal cycle of canopy temperature, not primary production: evidence from remote sensing
Authors: Foster P. N. , Prentice I. C. , Morfopoulos C. , Siddall M. , van Weele M.
Published: December 2013

Abstract. Isoprene is important in atmospheric chemistry, but its seasonal emission pattern – especially in the tropics, where most isoprene is emitted – is incompletely understood. We set out to discover general, biome-independent relationships between large-scale isoprene emission and a series of potential predictor variables, including both observed and model-estimated variables related to gross primary production (GPP) and canopy temperature. To this end we used remotely sensed atmospheric concentrations of formaldehyde, an intermediate oxidation product of isoprene, as a proxy for isoprene emission in 22 regions selected to span high to low latitudes, to sample major biomes, and to minimize interference from pyrogenic sources of volatile organic compounds that could interfere with the isoprene signal. Formaldehyde concentrations showed the highest average seasonal correlations with remotely sensed (r = 0.85) and model-estimated (r = 0.80) canopy temperatures. Both variables predicted formaldehyde concentrations better than air temperature (r = 0.56) and a "reference" isoprene model that includes both temperature and GPP (r = 0.49), and far better than either remotely sensed green vegetation cover (r = 0.25) or model-estimated GPP (r = 0.14). GPP in tropical regions was anti-correlated with formaldehyde concentration (r = –0.30), which peaks during the dry season. We conjecture that the positive correlations of isoprene emission with primary production, and with air temperature, found in temperate forest regions arise simply because all three peak during the relatively short growing season. In most tropical regions, where the seasonal cycles of GPP and canopy temperature are very different, isoprene emission is revealed to depend on canopy temperature but not at all on GPP. The lack of a general correlation between GPP and formaldehyde concentration is consistent with experimental evidence that isoprene emission is decoupled from photosynthesis, and with the likely adaptive significance of isoprene emission in protecting leaves against heat damage and oxidative stress. In contrast, the high correlation between canopy temperature and formaldehyde concentration indicates the importance of including canopy temperature explicitly in large-scale models.
Projecting Antarctic ice discharge using response functions from SeaRISE ice-sheet models
Authors: Levermann A. , Winkelmann R. , Nowicki S. , Fastook J. L. , Frieler K. , Greve R. , Hellmer H. H. , Martin M. A. , Mengel M. , Payne A. J. , Pollard D. , Sato T. , Timmermann R. , Wang W. L. , Bindschadler R. A.
Published: December 2013

Abstract. The largest uncertainty in projections of future sea-level change results from the potentially changing dynamical ice discharge from Antarctica. Basal ice-shelf melting induced by a warming ocean has been identified as a major cause for additional ice flow across the grounding line. Here we derive dynamic ice-sheet response functions for basal ice-shelf melting for four different Antarctic drainage regions using experiments from the Sea-level Response to Ice Sheet Evolution (SeaRISE) intercomparison project with five different Antarctic ice-sheet models. Under the assumptions of linear-response theory we project future ice-discharge for each model, each region and each of the four Representative Concentration Pathways (RCP) using oceanic temperatures from 19 comprehensive climate models of the Coupled Model Intercomparison Project, CMIP-5, and two ocean models from the EU-project Ice2Sea. The uncertainty in the climatic forcing, the oceanic response and the ice-model response is combined into an uncertainty range of future Antarctic ice-discharge induced from basal ice-shelf melt. The uncertainty range we derived for the Antarctic contribution to global sea-level rise from 1992 to 2011 is in full agreement with the observed contribution for this period if we use the three ice-sheet models with an explicit representation of ice-shelf dynamics and account for the time delayed warming of the oceanic subsurface compared with the surface air temperature. The median of the additional ice-loss for the 21st century (Table 6) is 0.07 m (66%-range: 0.02–0.14 m; 90%-range: 0.0–0.23 m) of global sea-level equivalent for the low-emission RCP-2.6 scenario and 0.09 m (66%-range: 0.04–0.21 m; 90%-range: 0.01–0.37 m) for the strongest RCP-8.5 if models with explicit ice-shelf representation are applied. These results were obtained using a time delay between the surface warming signal and the subsurface oceanic warming as observed in the CMIP-5 models. Without this time delay the values increase to 0.09 m (66%-range: 0.04–0.17 m; 90%-range: 0.02–0.25 m) for RCP-2.6 and 0.15 m (66%-range: 0.07–0.28 m; 90%-range: 0.04–0.43 m) for RCP-8.5. Our results are scenario dependent which is most visible in the upper percentiles of the distribution, i.e. highest contributions to sea level rise. All probability distributions, as provided in Fig. 12, are highly skewed towards high values. The applied ice-sheet models are coarse-resolution with limitations in the representation of grounding-line motion. However, we find the main uncertainty to be introduced by the external forcing to the ice-sheets, i.e. the climatic and oceanic uncertainty dominate. The scaling coefficients for the four different drainage basins provide valuable information for further assessments of future Antarctic ice discharge.
Tsunami evacuation modelling as a tool for risk reduction: application to the coastal area of El Salvador
Authors: González-Riancho P. , Aguirre-Ayerbe I. , Aniel-Quiroga I. , Abad S. , González M. , Larreynaga J. , Gavidia F. , Gutiérrez O. Q. , Álvarez-Gómez J. A. , Medina R.
Published: December 2013

Abstract. Advances in the understanding and prediction of tsunami impacts allow the development of risk reduction strategies for tsunami-prone areas. This paper presents an integral framework for the formulation of tsunami evacuation plans based on tsunami vulnerability assessment and evacuation modelling. This framework considers (i) the hazard aspects (tsunami flooding characteristics and arrival time), (ii) the characteristics of the exposed area (people, shelters and road network), (iii) the current tsunami warning procedures and timing, (iv) the time needed to evacuate the population, and (v) the identification of measures to improve the evacuation process. The proposed methodological framework aims to bridge between risk assessment and risk management in terms of tsunami evacuation, as it allows for an estimation of the degree of evacuation success of specific management options, as well as for the classification and prioritization of the gathered information, in order to formulate an optimal evacuation plan. The framework has been applied to the El Salvador case study, demonstrating its applicability to site-specific response times and population characteristics.
Modeling of the cave-ins occurrence using AHD and GIS
Authors: Malinowska A. A. , Dziarek K.
Published: December 2013

Abstract. The analysis of mining-induced sinkholes occurrence is a very important problem as far as the spatial development optimization is concerned. Research conducted within this paper was oriented to revealing the applicability of GIS and the associated AHD method for estimating the risk of discontinuous deformation occurrence on the surface. The qualitative factors were accounted for in the sinkhole risk assessment, thus creating bases for the research. These elements play an important role in the process of sinkholes formation; however they were not used in prediction models. Another assumption lied in minimizing the number of variables in the model. Accordingly, the most important qualitative and quantitative risk factors were finally selected, on the basis of which the risk of cave-ins occurrence on the surface could be calculated. The results of estimations of zones with sinkholes potential were verified. The places of actual and high-risk potential discontinuous deformations were compared. The congruence between predicted values and actual observations of sinkholes was very high. The results of presented research prove the necessity to evaluate the sinkhole hazard in view of qualitative factors.
The morphology and surface features of olivine in kimberlite lava: implications for ascent and emplacement mechanisms
Authors: Jones T. J. , Russell J. K. , Porritt L. A. , Brown R. J.
Published: December 2013

Abstract. Many kimberlite rocks contain large proportions of ellipsoidal-shaped xenocrystic olivine grains that are derived mainly from the disaggregation of peridotite. Xenocrystic olivine grains from a lava erupted from the Quaternary Igwisi Hills kimberlites, Tanzania, are compared to phenocrystic olivine, liberated from picritic lavas, and mantle olivine, liberated from a fresh peridotite xenolith, in order to examine the potential modification of olivine surface textures due to transport from the mantle to the surface within kimberlite magmas. Image analysis, SEM imagery and laser microscopy reveals significant differences in the surface features and morphologies of the three crystal populations. Xenocrystic olivine grains are characterised by rough surfaces, ellipsoidal shapes and impact pits. Mantle olivines are characterised by flaked surfaces and indented shapes consistent with growth as a crystal aggregates. Phenocrystic olivines are smooth-surfaced and exhibit flat crystal faces. We infer that the distinctive shapes and surfaces of xenocrystic olivine grains resulted from three distinct mechanical processes attending their rapid transport from their source in the mantle lithosphere: (1) penetrative flaking from micro-tensile failure induced by rapid decompression; (2) sustained abrasion and attrition arising from particle-particle collisions between grains in a turbulent, volatile-rich flow regime, and; (3) higher energy particle-particle collisions that produced impact cavities superimposed on decompression structures. The combination of these processes during the rapid ascent of kimberlite magmas is responsible for the distinctive ellipsoidal shape of olivine xenocrysts found in kimberlites worldwide.
Brief Communication: Low-cost, on-demand aerial photogrammetry for glaciological measurement
Authors: Whitehead K. , Moorman B. J. , Hugenholtz C. H.
Published: December 2013

Abstract. Remotely sensed glaciological measurements can be expensive, often involving a trade-off between resolution, scale, and frequency. We report on a case study in which two low-cost techniques were used to generate digital elevation models and orthomosaics of an Arctic glacier in consecutive ablation seasons. In the first aerial survey we used an unmanned aerial vehicle and acquired images autonomously. The following year we took advantage of the helicopter used for site access, and were able to acquire images manually, for little additional helicopter time. We present a preliminary assessment of accuracy and apply these data to measure glacier thinning and motion.
The growth of sublimation crystals and surface hoar on the Antarctic plateau
Authors: Gallet J.-C. , Domine F. , Savarino J. , Dumont M. , Brun E.
Published: December 2013

Abstract. On the Antarctic plateau, the budget of water vapor and energy is in part determined by precipitation, but these are so low that the dynamic of snow crystal growth and sublimation at the surface can be important factors. At Dome C (75° S, 123° E), we have frequently observed the growth of crystals on the snow surface under calm sunny weather. Here, we present the time variations of specific surface area and density of these crystals. Using the detailed snow model Crocus, we conclude that these crystals were very likely due to the nighttime formation of surface hoar crystals and to the daytime formation of sublimation crystals. These latter crystals form by processes similar to those involved in the formation of frost flowers on young sea ice. The formation of these crystals impact the albedo, mass and energy budget of the Antarctic plateau. In particular, the specific surface area variations of the surface layer can induce an instantaneous forcing of up to −10 W m−2 at noon, resulting in a surface temperature drop of 0.45 K.
PepArML: A Meta‐Search Peptide Identification Platform for Tandem Mass Spectra
Authors: Edwards Nathan J.
Published: December 2013

The PepArML meta‐search peptide identification platform for tandem mass spectra provides a unified search interface to seven search engines; a robust cluster, grid, and cloud computing scheduler for large‐scale searches; and an unsupervised, model‐free, machine‐learning‐based result combiner, which selects the best peptide identification for each spectrum, estimates false‐discovery rates, and outputs pepXML format identifications. The meta‐search platform supports Mascot; Tandem with native, k‐score and s‐score scoring; OMSSA; MyriMatch; and InsPecT with MS‐GF spectral probability scores—reformatting spectral data and constructing search configurations for each search engine on the fly. The combiner selects the best peptide identification for each spectrum based on search engine results and features that model enzymatic digestion, retention time, precursor isotope clusters, mass accuracy, and proteotypic peptide properties, requiring no prior knowledge of feature utility or weighting. The PepArML meta‐search peptide identification platform often identifies two to three times more spectra than individual search engines at 10% FDR. Curr. Protoc. Bioinform. 44:13.23.1‐13.23.23. © 2013 by John Wiley & Sons, Inc.
Annual net community production and the biological carbon flux in the ocean
Authors: Emerson Steven
Published: December 2013

The flux of biologically produced organic matter from the surface ocean (the biological pump), over an annual cycle, is equal to the annual net community production (ANCP). Experimental determinations of ANCP at ocean time series sites using a variety of different metabolite mass balances have made it possible to evaluate the accuracy of sediment trap fluxes and satellite‐determined ocean carbon export. ANCP values at the Hawaii Ocean Time‐series (HOT), the Bermuda Atlantic Time‐series Study (BATS), Ocean Station Papa (OSP) are 3 ± 1 mol C m−2 yr−1—much less variable than presently suggested by satellite remote sensing measurements and global circulation models. ANCP determined from mass balances at these locations are 3–4 times particulate organic carbon fluxes measured in sediment traps. When the roles of dissolved organic carbon (DOC) flux, zooplankton migration, and depth‐dependent respiration are considered these differences are reconciled at HOT and OSP but not at BATS, where measured particulate fluxes are about 3 times lower than expected. Even in the cases where sediment trap fluxes are accurate, it is not possible to “scale up” these measurements to determine ANCP without independent determinations of geographically variable DOC flux and zooplankton migration. Estimates of ANCP from satellite remote sensing using net primary production determined by the carbon‐based productivity model suggests less geographic variability than its predecessor (the vertically generalized productivity model) and brings predictions at HOT and OSP closer to measurements; however, satellite‐predicted ANCP at BATS is still 3 times too low.
Radio‐tomographic images of postmidnight equatorial plasma depletions
Authors: Hei Matthew A. , Bernhardt Paul A. , Siefring Carl L. , Wilkens Matthew R. , Huba Joseph D. , Krall Jonathan F. , Valladares Cesar E. , Heelis Roderick A. , Hairston Marc R. , Coley W. Robin , Chau Jorge L. , De La Jara Cesar
Published: December 2013

For the first time, equatorial plasma depletions (EPDs) have been imaged in the longitude‐altitude plane using radiotomography. High‐resolution (~10 km) reconstructions of electron density were derived from total electron content (TEC) measurements provided by a receiver array in Peru. TEC data were obtained from VHF/UHF signals transmitted by the Coherent Electromagnetic Radio Tomography (CERTO) beacon on the C/NOFS satellite. EPDs generated premidnight were observed near dawn. On one night, the bubble densities were highly reduced, 100–1000 km wide, and embedded within a layerlike ionosphere. Three nights later, the EPDs exhibited similar features but were embedded in a locally uplifted ionosphere. The C/NOFS in situ instruments detected a dawn depletion where the reconstruction showed lifted EPDs, implying that the postmidnight electric fields raised sections of ionosphere to altitudes where embedded/reactivated fossil EPDs were detected as dawn depletions. Satellites flying under domelike distortions of the ionosphere may observe these distortions as broad plasma decreases (BPDs).
Variation of the solar magnetic flux spectrum during solar cycle 23
Authors: Jin C. L. , Wang J. X.
Published: December 2013

By using the unique database of Solar and Heliospheric Observatory/Michelson Doppler Imager full disk magnetograms from September 1996 to January 2011, covering the entire solar cycle 23, we analyze the time‐variability of the solar magnetic flux spectrum and study the properties of extended minimum of cycle 23. We totally identify 11.5 million magnetic structures. It has been revealed that magnetic features with different magnetic fluxes exhibit different cycle behaviors. The magnetic features with flux larger than 4.0×1019 Mx, which cover solar active regions and strong network features, show exactly the same variation as sunspots; however, the remaining 82% magnetic features which cover the majority of network elements show anti‐phase variation with sunspots. We select a criterion that the monthly sunspot number is less than 20 to represent the Sun's low activity status. Then we find the extended minimum of cycle 23 is characterized by the long duration of low activity status, but the magnitude of magnetic flux in this period is not lower than previous cycle. Both the duration of low activity status and the minimum activity level defined by minimum sunspot number show a century period approximately. The extended minimum of cycle 23 shows similarities with solar cycle 11, which preceded the mini‐maxima in later solar cycles. This similarity is suggestive that the solar cycles following cycle 23 are likely to have low activity.