bluuebunny/crossref_metadata_2025 huggingface dataset:
Atmospheric Corrosion in Marine Environments
Authors: LEGAULT R. A. , PEARSON V. P.
Published: February 2013

It has been demonstrated that the natural atmospheric corrosion behavior of low alloy steels in marine environments can be accurately described by an equation of the form: ΔW = KtN. With this relationship, reliable predictions of long term weight losses can be made from as few as two sets of determinations obtained in relatively short exposures. The reliability of this relationship has also been established for galvanized and aluminized steels.
The Relationship Between Repassivation Behavior and Pitting Corrosion for Ti and Ti6AI4V
Authors: RAETZER-SCHEIBE H. -J.
Published: February 2013

The characteristic pitting potentials of Ti and Ti6AI4V were determined by measurement of potentiodynamic current-potential curves in solutions of 1N NaCl, 1N Nal, and 1N NaBr. Under the same conditions current-time curves were measured for various potentials after generation of a new metallic surface. By means of these curves, one can study the repassivation behavior of materials. The comparison between the potential of pit repassivation and the repassivation/nonrepassivation potential shows a relatively good correlation. The determination of the critical repassivation potentials enables us to predict the pitting corrosion behavior.
Influence of Density and Distribution of Intergranular Sulfides on the Sulfide Stress Cracking Properties of High Strength Steels
Authors: JOSHI A.
Published: February 2013

The common occurrence of sulfide stress cracking failures of many steels in the intergranular mode suggests a need for a better understanding of the grain boundaries, particularly the boundary chemistry. The boundary chemistry of selected high strength steels is correlated to the minimum stress at failure in hydrogen sulfide solutions at room temperature. The technique of Auger electron spectroscopy (AES) in a scanning Auger microprobe was employed to study grain boùndary composition and distribution of second phases at fresh fracture surfaces. The results indicate that S and Mn, precipitated in the form of a thin film of (Fe, Mn)S or P present at grain boundaries degrade the SSC properties of the material.
Microstructure and Chemical Composition of Natural Scale Layers
Authors: FEIGENBAUM C. , GAL-OR L , YAHALOM J.
Published: February 2013

Basic physico-chemical data required to understand the mechanism of corrosion protection by natural scale layers in water pipes were investigated. These included the morphology, distribution of constituent elements, and crystalline phase composition of 15 natural scale layers, formed in potable water supply mains carrying water of various chemical compositions. Using scanning electron microscopy, the morphological studies reveal the following structure: the outer zone (adjacent to the scale/water interface) is relatively compact and consists of contiguous crystals, while the inner zone is considerably more porous. This morphological heterogeneity is explained by differences in crystallographic and chemical composition of the two zones. Crystalline phase analysis of the scales was performed by the Debye-Scherrer method on powdered samples. It was found that calcite-CaCO3, which favors a compact arrangement, appears in the outer zone, while the inner zone is comprised of geothite [α FeO(OH)], siderite (FeCO3), and magnetite (Fe3O4), that favor both needle-like and granular porous structures. Independent microanalysis studies showed the occurrence of a steep gradient in Fe and Ca concentrations inside the bulk of the scale. The location of this gradient in terms of scale depth varies from scale to scale and plays a significant role in corrosion protection. The Fe/Ca ratio as determined by overall chemical analysis varied over the range 0.2 < /Fe/Ca < 182.
Chelate Inhibitors for Zinc and Galvanized Products
Authors: LEROY RODNEY L.
Published: February 2013

White rust corrosion of zinc and galvanized products remains a serious commercial problem, in spite of almost 50 years of development of inorganic passivation techniques. Furthermore, such inhibitors compound the already difficult task of paint application to these materials. In a novel approach, the concept of surface chealtion has been taken as a starting point for the development of organic inhibitors for zinc which will act as monolayers strongly bonded to the metal substrate. Possible chelating groups were screened, resulting in identification of two particularly effective materials: (1) 2,5-dimercapto-1,3,4-thiadiazole, and (2) the esters of thioglycolic acid.
Caustic Stress Corrosion Cracking Studies at 288 C (550 F) Using the Straining Electrode Technique — Comparison of Alloy 600, Alloy 800, and Type 304 Stainless Steel
Authors: CELS J. R.
Published: February 2013

Constant pull rate tests were conducted on tensile specimens of Inconel Alloy 600, Incoloy Alloy 800, and Type 304 stainless steel in deaerated 10% NaOH solution at 288 C (550 F) with a cover gas of 5% H2 in N2. The pull rate used for most experiments was 3.3 x 10−6 cm/s, which corresponds to an initial strain rate of 3 x 10−6 s−1. The electrical potential of the specimens was controlled by a potentiostat using a nickel wire as a hydrogen reference electrode. Under open circuit conditions, Type 304 stainless steel specimens cracked rapidly, but Alloys 600 and 800 specimens exhibited only ductile fracture. However, cracks readily formed in Alloy 800 specimens at potentials in the +50 to +300 mV range and in Alloy 600 specimens at potentials in the +150 to +250 mV range. Scanning electron microscope (SEM) photographs of some of the cracked specimen surfaces showed the transition from ductile to brittle fracture as a consequence of changes in the specimen's electrical potential. Longitudinal metallographic cross sections also revealed the grain structure and the mode of cracking. They showed that the cracks were intergranular in Alloy 600 and Type 304 stainless steel specimens, and were transgranular in Alloy 800 specimens.
Evaluation of Liquid-Metal-Embrittlement by the Quasistatic Crack Propagation Technique
Authors: MAI Y. W.
Published: February 2013

This paper describes a simple quasi-static crack propagation technique which is conveniently used for the evaluation of fracture resistances of metals as embrittled by liquid-metals. Examples given are cast iron, zinc alloy, and alpha-brass immersed in a 0.1 molar mercurous nitrate solution. The advantages and disadvantages of the quasi-static graphical analysis are also discussed.
A Laser Interferometric Study of Corrosion of Coated and Uncoated Metals I. — Technique Standardization with the Zn/ZnSO4/Zn System
Authors: O'BRIEN R. N. , KOLNY H.
Published: February 2013

A laser interferometric method of detecting holidays in and evaluating the corrosion protection of epoxy primer or other coatings was tested in the well known system Zn/ZnSO4/Zn. An electrochemical potential in the general range of corrosion couple values was applied, first to uncoated electrodes, then to coated anodes with measured, prepared holidays. The method is shown to give easily interpretable, visually obvious qualitative results. General methods of calculating good relative values and less accurate true values of corrosion currents are evolved.
Low Temperature Sensitization of Welded Type 304 Stainless Steel
Authors: POVICH M. J. , RAO P.
Published: February 2013

It has been shown that the sensitization of Type 304 stainless steel occurs at temperatures well below the normal isothermal temperature range for sensitization. A prerequisite for this low temperature sensitization (LTS) is the presence of chromium carbide nuclei along grain boundaries. This paper shows that the thermal exposure during welding can nucleate the grain boundary carbides necessary for subsequent LTS. Quantitative transmission electron microscopy studies show that no new carbides nucleate during an LTS heat treatment at 400 C. However, carbides that were nucleated at the time of welding grow during the LTS heat treatment. These findings are consistent with the proposed nucleation and growth LTS model. Using an accelerated test for intergranular stress corrosion cracking (IGSCC) in high temperature, high purity, 8 ppm oxygen water, it has been found that the rate of LTS in a Type 304 stainless steel weld heat affected zone obeys an Arrhenius temperature dependence which predicts that LTS enhanced susceptibility to IGSCC may occur in less than 10 years at 300 C. Similar IGSCC tests in water containing reduced dissolved oxygen indicate that reducing the oxygen level to 0.2 ppm would greatly reduce the probability of IGSCC, even in low temperature sensitized Type 304 stainless steel. The value of LTS as an improved screening test for the presence of carbides and for the qualification of mill annealed stainless steel is noted.
The Use of Potential-pH Diagrams for the Interpretation of Corrosion Phenomena in High Salinity Geothermal Brines
Authors: MACDONALD DIGBY D. , SYRETT BARRY C. , WING SHARON S.
Published: February 2013

Corrosion potentials and cyclic voltammograms are reported for AISI 1010 carbon steel, E-Brite 26-1 stainless steel, AISI 316L stainless steel, Haynes Alloy 20 Mod, Carpenter 20 Cb-3, Inconel Alloy 625, Hastelloy Alloy G, Hastelloy Alloy C-276, Titanium 50A, and TiCode 12 in high salinity geothermal brine at 250 C. Potential-pH diagrams for the component metals (Fe, Ni, Cr, Ti) in the brine at 25 and 250 C are also derived, and are used to interpret the corrosion behavior and cyclic voltammetric responses of the alloys in the elevated temperature brine environment.
Flow Effects on Corrosion of Galvanic Couples in Sea Water
Authors: PERKINS JEFF , GRAHAM K. J. , STORM G. A. , LEUMER G. , SCHACK R. P.
Published: February 2013

A unique “circling-foil” apparatus has been developed to study velocity effects on corrosion processes, and has been used initially to expose single metals and galvanic couples of some common marine structural materials in synthetic sea water electrolyte under controlled hydrodynamic conditions at relative velocities up to 3 m/s. The samples are deployed by mounting in a sample holder with a standard foil profile, which circles in a tank, with a turbulence trip wire at the leading edge of the foil. This scheme allows prediction and measurement of the fluid flow structure over the corrosion samples. Direct determinations of turbulence intensity and boundary layer thickness were made at various velocities, enabling correlations of hydrodynamic parameters with electrochemical data and other measures of corrosion behavior. The effects of velocity and potential distribution on average corrosion rates, and on the mode and distribution of corrosive attack and corrosion products, have been studied.
Corrosion Pretreatments for Copper-Zinc Alloys
Authors: POLING G. W. , NOTOYA T.
Published: February 2013

Combinations of four different types of zinc complexing agents with benzotriazole (BTA), an efficient complexant and corrosion inhibitor for copper, were tested as pretreatment inhibitors for 70/30 and 60/40 brasses in aerated 3% NaCI solutions. Alkyl dithiocarbonates, of C6 to C8 chain length, proved superior to: 2, 5-dimercaptothiadiazole (DMTDA), sodium-diethyldithiocarbamate (DDC), and sodium diethyldithiophosphate (DEDTP), in combination with BTA under a variety of test conditions. Apart from acting as an acid inhibitor for 70/30 brass exposed to acidic NaCI solutions, the DMTDA was also an effective partner inhibitor for BTA. Combinations of the other two complexing agents (DDC and DEDTP) plus BTA actually accelerated the corrosion of 70/30 brass but provided good protection of 60/40 brass in the NaCI solutions. Scanning electron micrographs showing surface topographies of test specimens with and without these inhibitor pretreatments are presented. Galvanostatic polarization curves are shown to help evaluate the inhibiting action of each inhibitor combination.
Effect of Prestrain on Stress Corrosion Cracking of Type 304 Stainless Steel by Means of the Stress Relaxation Method
Authors: KAMIDE HIDEHIKO , SUGAWARA HIDEO
Published: February 2013

The relationship between the susceptibility of stress corrosion cracking (SCC) and the amount of deformation structures in Type 304 stainless steel in an H2SO4/NaCI solution system at room temperature was investigated by means of the stress relaxation method. SCC was observed in the prestrained specimens, whereas no cracking occurred in specimens without prestraining. The number of cracks was affected by the amount of deformation structures, which varied according to the annealing temperature after prestraining or according to the prestraining temperature. The results of magnetic measurements on the prestrained specimens as a function of the annealing temperature showed that the cracking region was in good agreement with the range of existence of strain induced α-martensites. Transmission electron microscope observation showed that ε- and α-martensites formed by prestraining at temperatures below 413 K (140 C) dissolved in preference to the austenite matrix. A strain induced martensite in Type 304 stainless steel seems to precede cracking in this system.
Impedance and Potential Behavior of Surface Oxide Films on Hafnium Electrodes
Authors: EL-BASIOUNY M. S. , BEKHEET A. M. , HEFNY M. M.
Published: February 2013

The open circuit behavior of hafnium at different surface film thicknesses, immersed in 0.5N H2SO4 has been investigated using potential and impedance measurements. When the anodic current is interrupted, a decrease in oxide film thickness (thinning) was attributed mainly to chemical dissolution of the barrier film. A full inertness of the surface is attained when the polarization potential reaches around 25 V (NHE) where the surface film becomes insoluble in the surrounding electrolyte. It was found also that with gradual accumulation of the oxide layer, a pronounced increase of the open circuit potential was observed. At the thickness corresponding to the polarization potential 25 V (NHE), the rate of increase of open circuit potential after cessation of the current becomes very much reduced and thus a perfect, compact, and continuous oxide film was assumed to be formed on the metal surface.
Parametric Evaluation of Susceptibility of Cu-Ni Alloys to Sulfide Induced Corrosion in Sea Water
Authors: GUDAS JOHN P. , HACK HARVEY P.
Published: February 2013

Experiments were performed to determine susceptibility of 90/10 and 70/10 Cu-Ni alloys to sulfide induced corrosion as related to sulfide concentration, sea water velocity, and duration of sulfide exposure. All exposures were conducted in fresh sea water, and the range of experimental variables included sulfide concentration (from sodium sulfide) from 0.007 to 0.25 mg/L, sea water velocity after sulfide exposure from 0.5 to 5.3 m/s, and sulfide exposure times from 1 to 90 days. Results showed that both alloys undergo localized attack in sea water environments with as little as 0.007 mg/L sulfide. The velocity dependence of active attack was minimal in the range tested. Duration of sulfide exposure, particularly at low sulfide concentrations, is a key factor in causing localized corrosion in these alloys and in the degree of attack experienced. On the basis of long term continuous low concentration sulfide exposure, 70/30 Cu-Ni appears to undergo less severe attack than that seen with 90/10 Cu-Ni.
Preparation and Characterization of Model Colloidal Corrosion Products
Authors: MATIJEVIC EGON
Published: February 2013

Model colloidal corrosion products consisting of ferric hydrous oxides, cobalt oxide, and chromium hydroxide particles of well defined shape and uniform size have been prepared. These systems are used to elucidate the mechanism of formation of such materials from aqueous solutions, with special emphasis on the nature and the distribution of solute complexes which act as precursors to precipitation. The role of the anions on the composition and the morphology of the resulting metal hydrous oxide solids is stressed. The so prepared model systems are also used to study properties of the solids and their reactions which are of interest in corrosion of metals. In this work, the magnetic characteristics of iron (III) hydrous oxides as a function of their composition, as well as particle size and shape, are illustrated and discussed. Furthermore, the interactions of a ferric oxyhydroxide with EDTA, a chemical decontaminant for nuclear reactors, has been investigated. It was shown that the stability of these particles and their rate of dissolution is strictly related to the adsorption of this ligand material on the metal hydrous oxide. Finally, the adhesion of chromium hydroxide particles on steel and their removal has been followed as a function of solution conditions (pH, electrolyte presence). The better data could be explained in terms of the theory of the electrical double layer.
Influence of surface albedo heterogeneity on passive remote sensing of cirrus properties
Authors: Fricke C. , Ehrlich A. , Jäkel E. , Bohn B. , Wirth M. , Wendisch M.
Published: February 2013

Abstract. Airborne measurements of solar spectral radiance reflected by cirrus are performed with the HALO-SR instrument onboard the High Altitude and Long Range Research Aircraft (HALO) in November 2010. The data are used to quantify the influence of surface albedo heterogeneities on the retrieval of cirrus optical thickness and crystal effective radius. Based on radiative transfer calculations the cirrus properties are derived using a standard bispectral retrieval method. Frequency distributions of the surface albedos derived from MODIS satellite observations are used to create albedo dependend lookup tables of reflected radiance. For each albedo respectively lookup table, a corresponding result for the cirrus optical thickness and effective radius is retrieved. The retrieved cloud properties are analysed in a statistical manner to investigate the influence of surface albedo heterogeneities. The results for the cirrus optical thickness are compared to HSRL-lidar derived values which allows to investigate the role of ice crystal shape in addition. It is found that if assuming aggregate ice crystals the HSRL-lidar observations fit best to the retrieved optical thickness using spectral radiance. The uncertainty in cirrus optical thickness due to uncertainties in the surface albedo is below 0.1 and thus below the instrument uncertainty. Therefor, it is concluded that for the retrieval of cirrus optical thickness the surface albedo heterogeneity is negligible. For the retrieval of cirrus effective radius, the surface albedo is of importance introducing uncertainties up to 50%. However, it was be shown that the influence of the bidirectional reflectance distribution function (BRDF) is below 10% and thus smaller than the uncertainty caused by the surface albedo.
Evaluation of a cavity ring-down spectrometer for in situ observations of 13CO2
Authors: Vogel F. R. , Huang L. , Ernst D. , Giroux L. , Racki S. , Worthy D. E. J.
Published: February 2013

Abstract. With the emergence of wide-spread application of new optical techniques to monitor δ13C in atmospheric CO2 there is a growing need to ensure well-calibrated measurements. We characterized one commonly available instrument, a cavity ring-down spectrometer (CRDS) system used for continuous in situ monitoring of atmospheric 13CO2. We found no dependency of δ13C on the CO2 concentration in the range of 303–437 ppm. We designed a calibration scheme according to the diagnosed instrumental drifts and established a quality assurance protocol. We find that the repeatability (1-σ) of measurements is 0.25‰ for 10 min and 0.15‰ for 20 min integrated averages, respectively. Due to a spectral overlap, our instrument displays a cross-sensitivity to CH4 of 0.42 ± 0.024‰ ppm−1. Our ongoing target measurements yield standard deviations of δ13C from 0.22‰ to 0.28‰ for 10 min averages. We furthermore estimate the reproducibility of our system for ambient air samples from weekly measurements of a long-term target gas to be 0.18‰. We find only a minuscule offset of 0.002 ± 0.025‰ between the CRDS and Environment Canada's isotope ratio mass spectrometer (IRMS) results for four target gases used over the course of one year.
An overview of drought events in the Carpathian Region in 1961–2010
Authors: Spinoni J. , Antofie T. , Barbosa P. , Bihari Z. , Lakatos M. , Szalai S. , Szentimrey T. , Vogt J.
Published: February 2013

Abstract. The Carpathians and their rich biosphere are considered to be highly vulnerable to climate change. Drought is one of the major climate-related damaging natural phenomena and in Europe it has been occurring with increasing frequency, intensity, and duration in the last decades. Due to climate change, land cover changes, and intensive land use, the Carpathian Region is one of the areas at highest drought risk in Europe. In order to analyze the drought events over the last 50 yr in the area, we used a 1961–2010 daily gridded temperature and precipitation dataset. From this, monthly 0.1° × 0.1° grids of four drought indicators (Standardized Precipitation-Evapotranspiration Index (SPEI), Standardized Precipitation Index (SPI), Reconnaissance Drought Indicator (RDI), and Palfai Aridity/Drought Index (PADI)) have been calculated. SPI, SPEI, and RDI have been computed at different time scales (3, 6, and 12 months), whilst PADI has been computed on an annual basis. The dataset used in this paper has been constructed in the framework of the CARPATCLIM project, run by a consortium of institutions from 9 countries (Austria, Croatia, Czech Republic, Hungary, Poland, Romania, Serbia, Slovakia, and Ukraine) with scientific support by the Joint Research Centre (JRC) of the European Commission. Temperature and precipitation station data have been collected, quality-checked, completed, homogenized, and interpolated on the 0.1° × 0.1° grid, and drought indicators have been consequently calculated on the grid itself. Monthly and annual series of the cited indicators are presented, together with high-resolution maps and statistical analysis of their correlation. A list of drought events between 1961 and 2010, based on the agreement of the indicators, is presented. We also discuss three case studies: drought in 1990, 2000, and 2003. The drought indicators have been compared both on spatial and temporal scales: it resulted that SPI, SPEI, and RDI are highly comparable, especially over a 12-month accumulation period. SPEI, which includes PET (Potential Evapo-Transpiration) as RDI does, proved to perform best if drought is caused by heat waves, whilst SPI performed best if drought is mainly driven by a rainfall deficit, because SPEI and RDI can be extreme in dry periods. According to PADI, the Carpathian Region has a sufficient natural water supply on average, with some spots that fall into the ''mild dry'' class, and this is also confirmed by the FAO-UNEP aridity index and the Köppen-Geiger climate classification.
Estimation of the global inventory of methane hydrates in marine sediments using transfer functions
Authors: Piñero E. , Marquardt M. , Hensen C. , Haeckel M. , Wallmann K.
Published: February 2013

Abstract. The accumulation of gas hydrates in marine sediments is essentially controlled by the accumulation of particulate organic carbon (POC) which is microbially converted into methane, the thickness of the gas hydrate stability zone (GHSZ) where methane can be trapped, the sedimentation rate (SR) that controls the time that POC and the generated methane stays within the GHSZ, and the delivery of methane from deep-seated sediments by ascending pore fluids and gas into the GHSZ. Recently, Wallmann et al. (2012) presented transfer functions to predict the gas hydrate inventory in diffusion-controlled geological systems based on SR, POC and GHSZ thickness for two different scenarios: normal and full compacting sediments. We apply these functions to global data sets of bathymetry, heat flow, seafloor temperature, POC input and SR, estimating a global mass of carbon stored in marine methane hydrates from 3 to 455 Gt of carbon (GtC) depending on the sedimentation and compaction conditions. The global sediment volume of the GHSZ in continental margins is estimated to be 60–67 × 1015 m3, with a total of 7 × 1015 m3 of pore volume (available for GH accumulation). However, seepage of methane-rich fluids is known to have a pronounced effect on gas hydrate accumulation. Therefore, we carried out a set of systematic model runs with the transport-reaction code in order to derive an extended transfer function explicitly considering upward fluid advection. Using averaged fluid velocities for active margins, which were derived from mass balance considerations, this extended transfer function predicts the enhanced gas hydrate accumulation along the continental margins worldwide. Different scenarios were investigated resulting in a global mass of sub-seafloor gas hydrates of ~ 550 GtC. Overall, our systematic approach allows to clearly and quantitatively distinguish between the effect of biogenic methane generation from POC and fluid advection on the accumulation of gas hydrate, and hence, provides a simple prognostic tool for the estimation of large-scale and global gas hydrate inventories in marine sediments.
Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA
Authors: Buzzelli C. , Wan Y. , Doering P. H. , Boyer J. N.
Published: February 2013

Abstract. Interactions among watershed nutrient loading, circulation, and biogeochemical cycling determine the capacity of estuaries to accommodate introduced nutrients. Baseline quantification of loading, flushing time, export, and internal processes is essential to understand responses of sub-tropical estuaries to variable climate and nutrient loading. The goal of this study was to develop seasonal dissolved inorganic nitrogen (DIN) and phosphorus (DIP) budgets for the two estuaries in south Florida, the Caloosahatchee River Estuary (CRE) and the St. Lucie Estuary (SLE), from 2002–2008 spanning various climatic conditions. The Land Ocean Interactions in the Coastal Zone (LOICZ) Biogeochemical Model was used to generate water, salt, and (DIN and DIP) budgets. The predicted increase in internal DIN production for the CRE vs. the SLE was associated with increased external DIN loading. Water column DIN concentrations decreased and stabilized in both estuaries as flushing time increased to > 10 d. The CRE demonstrated heterotrophy or balanced metabolism across all seasonal budgets. Although the SLE was also sensitive to DIN loading, system autotrophy and net ecosystem metabolism increased with DIP loading to this estuary. This included a huge DIP consumption and bloom of a cyanobacterium (Microcystis aeruginosa) following hurricane-induced discharge in 2005. Additionally, while denitrification offered a loss pathway for inorganic nitrogen in the CRE, this potential was not evident for the smaller and more anthropogenically altered St. Lucie Estuary. Disparities between total and inorganic loading ratios suggested that management actions should examine the role of dissolved organic nitrogen (DON) in attempts to reduce both nitrogen and phosphorus inputs to the SLE. Establishment of quantitative loading limits for anthropogenically impacted estuaries requires an understanding of the inter-seasonal and inter-annual relationships for both N and P, circulation and flushing, variability in plankton community composition, and the dynamics of DON.
Origin of the Hawaiian rainforest ecosystem and its evolution in long-term primary succession
Authors: Mueller-Dombois D. , Boehmer H. J.
Published: February 2013

Abstract. Born among volcanoes in the north central Pacific about 4 million years ago, the Hawaiian rainforest became assembled from spores of algae, fungi, lichens, bryophytes, ferns and from seeds of about 275 flowering plants that over the millenia evolved into ca. 1000 endemic species. Outstanding among the forest builders were the tree ferns (Cibotium spp.) and the 'Ōhi'a lehua trees (Metrosideros spp.), which still dominate the Hawaiian rainforest ecosystem today. The structure of this forest is simple. The canopy in closed mature rainforests is dominated by cohorts of Metrosideros polymorpha and the undergrowth by tree fern species of Cibotium. When a new lava flow cuts through this forest, kipuka are formed, i.e. islands of remnant vegetation. On the new volcanic substrate, the assemblage of plant life-forms is similar as during the evolution of this system. In open juvenile forests, a mat-forming fern, the uluhe fern (Dicranopteris lineraris) becomes established. It inhibits further regeneration of the dominant 'Ōhi'a tree, thereby reinforcing the cohort structure of the canopy guild. In the later part of its life cycle, the canopy guild breaks down often in synchrony. The trigger is hypothesized to be a climatic perturbation. After that disturbance the forest becomes reestablished in about 30–40 yr. As the volcanic surfaces age, they go from a mesotrophic to a eutrophic phase, reaching a biophilic nutrient climax by about 1–25 K yr. Thereafter, a regressive oligotrophic phase follows; the soils become exhausted of nutrients. The shield volcanoes break down. Marginally, forest habitats change into bogs and stream ecosystems. The broader 'Ōhi'a rainforest redeveloping in the more dissected landscapes of the older islands looses stature, often forming large gaps that are invaded by the aluminum tolerant uluhe fern. The 'Ōhi'a trees still thrive on soils rejuvenated from landslides and from Asian dust on the oldest (5 million year old) island Kaua'i but their stature and living biomass is greatly diminished.
Using paleo-climate comparisons to constrain future projections in CMIP5
Authors: Schmidt G. A. , Annan J. D. , Bartlein P. J. , Cook B. I. , Guilyardi E. , Hargreaves J. C. , Harrison S. P. , Kageyama M. , LeGrande A. N. , Konecky B. , Lovejoy S. , Mann M. E. , Masson-Delmotte V. , Risi C. , Thompson D. , Timmermann A. , Tremblay L.-B. , Yiou P.
Published: February 2013

Abstract. We present a description of the theoretical framework and "best practice" for using the paleo-climate model component of the Coupled Model Intercomparison Project (Phase 5) (CMIP5) to constrain future projections of climate using the same models. The constraints arise from measures of skill in hindcasting paleo-climate changes from the present over 3 periods: the Last Glacial Maximum (LGM) (21 thousand years before present, ka), the mid-Holocene (MH) (6 ka) and the Last Millennium (LM) (850–1850 CE). The skill measures may be used to validate robust patterns of climate change across scenarios or to distinguish between models that have differing outcomes in future scenarios. We find that the multi-model ensemble of paleo-simulations is adequate for addressing at least some of these issues. For example, selected benchmarks for the LGM and MH are correlated to the rank of future projections of precipitation/temperature or sea ice extent to indicate that models that produce the best agreement with paleoclimate information give demonstrably different future results than the rest of the models. We also find that some comparisons, for instance associated with model variability, are strongly dependent on uncertain forcing timeseries, or show time dependent behaviour, making direct inferences for the future problematic. Overall, we demonstrate that there is a strong potential for the paleo-climate simulations to help inform the future projections and urge all the modeling groups to complete this subset of the CMIP5 runs.
A vertically resolved, global, gap-free ozone database for assessing or constraining global climate model simulations
Authors: Bodeker G. E. , Hassler B. , Young P. J. , Portmann R. W.
Published: February 2013

Abstract. High vertical resolution ozone measurements from eight different satellite-based instruments have been merged with data from the global ozonesonde network to calculate monthly mean ozone values in 5° latitude zones. These ''Tier 0'' ozone number densities and ozone mixing ratios are provided on 70 altitude levels (1 to 70 km) and on 70 pressure levels spaced ~ 1 km apart (878.4 hPa to 0.046 hPa). The Tier 0 data are sparse and do not cover the entire globe or altitude range. To provide a gap-free database, a least squares regression model is fitted to the Tier 0 data and then evaluated globally. The regression model fit coefficients are expanded in Legendre polynomials to account for latitudinal structure, and in Fourier series to account for seasonality. Regression model fit coefficient patterns, which are two dimensional fields indexed by latitude and month of the year, from the N-th vertical level serve as an initial guess for the fit at the N + 1-th vertical level. The initial guess field for the first fit level (20 km/58.2 hPa) was derived by applying the regression model to total column ozone fields. Perturbations away from the initial guess are captured through the Legendre and Fourier expansions. By applying a single fit at each level, and using the approach of allowing the regression fits to change only slightly from one level to the next, the regression is less sensitive to measurement anomalies at individual stations or to individual satellite-based instruments. Particular attention is paid to ensuring that the low ozone abundances in the polar regions are captured. By summing different combinations of contributions from different regression model basis functions, four different ''Tier 1'' databases have been compiled for different intended uses. This database is suitable for assessing ozone fields from chemistry-climate model simulations or for providing the ozone boundary conditions for global climate model simulations that do not treat stratospheric chemistry interactively.
An optimally tuned ensemble of the "eb_go_gs" configuration of GENIE: parameter sensitivity and bifurcations in the Atlantic overturning circulation
Authors: Marsh R. , Sóbester A. , Hart E. E. , Oliver K. I. C. , Edwards N. R. , Cox S. J.
Published: February 2013

Abstract. The key physical parameters of the "eb_go_gs" configuration of GENIE, an Earth system Model of Intermediate Complexity (EMIC), are tuned using a multi-objective genetic algorithm. An ensemble of 90 parameter sets is tuned using two ocean and two atmospheric state variables as targets. These are "Pareto-optimal", representing a range of trade-offs between the four tuning targets. For the leading five parameter sets, simulations are further evaluated alongside a simulation with untuned "default" parameters, comparing selected variables and diagnostics that describe the state of the atmosphere, ocean and sea ice. One of these parameter sets is selected for further analysis of the objective function (error) landscape in the vicinity of its tuned values. "Cliffs" along some dimensions motivate closer inspection of corresponding variations in the Atlantic meridional overturning circulation (AMOC). This reveals that bifurcations in the AMOC are highly sensitive to parameters that are not commonly associated with MOC stability. Specifically, the state of the AMOC is sensitive to parameters governing the wind-driven circulation and atmospheric heat transport. Five optimal parameter sets are recommended for future use of GENIE in the configuration presented here.
Three-dimensional monitoring of soil water content in a maize field using Electrical Resistivity Tomography
Authors: Beff L. , Günther T. , Vandoorne B. , Couvreur V. , Javaux M.
Published: February 2013

Abstract. A good understanding of the soil water content (SWC) distribution at the field scale is essential to improve the management of water, soil and crops. Recent studies proved that Electrical Resistivity Tomography (ERT) opens interesting perspectives in the determination of the SWC distribution in 3 dimensions (3-D). This study was conducted (i) to check and validate how ERT is able to monitor SWC distribution in a maize field during the late growing season; and (ii) to investigate how maize plants and rainfall affect the dynamics of SWC distribution. Time Domain Reflectometry (TDR) measurements were used to validate ERT-inverted SWC values. Evolution of water mass balance was also calculated to check whether ERT was capable of giving a reliable estimate of soil water stock evolution. It is observed that ERT was able to give the same average SWC as TDR (R2 = 0.98). In addition, ERT gives better estimates of the water stock than TDR thanks to its higher spatial resolution. The high resolution of ERT measurements also allows for the discrimination of SWC heterogeneities. The SWC distribution showed that alternation of maize rows and inter-rows was the main influencing factor of the SWC distribution. The drying patterns were linked to the root profiles, with drier zones under the maize rows. During short periods, with negligible rainfall, the SWC decrease took place mainly in the two upper soil horizons and in the inter-row area. In contrast, rainfall increased the SWC mostly under the maize rows and in the upper soil layer. Nevertheless, the total amount of rainfall during the growing season was not sufficient to modify the SWC patterns induced by the maize rows. During the experimental time, there was hardly any SWC redistribution from maize rows to inter-rows. Yet, lateral redistribution from inter-rows to maize rows induced by potential gradient generates SWC decrease in the inter-row area and in the deeper soil horizons.
Identifying a parameterisation of the soil water retention curve from on-ground GPR measurements
Authors: Dagenbach A. , Buchner J. S. , Klenk P. , Roth K.
Published: February 2013

Abstract. We show the potential of on-ground Ground-Penetrating Radar (GPR) to identify the parameterisation of the soil water retention curve, i.e. its functional form, with a semi-quantitative analysis based on numerical simulations of the radar signal. An imbibition and drainage experiment has been conducted at the ASSESS-GPR site to establish a fluctuating water table, while an on-ground GPR antenna recorded traces over time at a fixed location. These measurements allow to identify and track the capillary fringe in the soil. The typical dynamics of soil water content with a transient water table can be deduced from the recorded radargrams. The characteristic reflections from the capillary fringes in model soils that are described by commonly used hydraulic parameterisations are investigated by numerical simulations. The parameterisations used are (i) full van Genuchten, (ii) simplified van Genuchten with m = 1 − 1/n and (iii) Brooks–Corey. All three yield characteristically different reflections, which allows the identification of an appropriate parameterisation by comparing to the measured signals. We show that for the sand used here, these signals are not consistent with the commonly used simplified van Genuchten parameterisation with m = 1 − 1/n.
An assessment of land use change impacts on the water resources of the Mula and Mutha Rivers catchment upstream of Pune, India
Authors: Wagner P. D. , Kumar S. , Schneider K.
Published: February 2013

Abstract. Land use changes are altering the hydrologic system and have potentially large impacts on water resources. Rapid socio-economic development drives land use change. This is particularly true in the case of the rapidly developing city of Pune, India. The present study aims at analyzing past land use changes between 1989 and 2009 and their impacts on the water balance in the Mula and Mutha Rivers catchment upstream of Pune. Land use changes were identified from three multitemporal land use classifications for the cropping years 1989/1990, 2000/2001, and 2009/2010. The hydrologic model SWAT (Soil and Water Assessment Tool) was used to assess impacts on runoff and evapotranspiration. Two model runs were performed and compared using the land use classifications of 1989/1990 and 2009/2010. The main land use changes were identified as an increase of urban area from 5.1% to 10.1% and cropland from 9.7% to 13.5% of the catchment area during the 20 yr period. Urbanization was mainly observed in the eastern part and conversion to cropland in the mid-northern part of the catchment. At the catchment scale we found that the impacts of these land use changes on the water balance cancel each other. However, at the sub-basin scale urbanization led to an increase of the water yield by up to 7.6%, and a similar decrease of evapotranspiration, whereas the increase of cropland resulted in an increase of evapotranspiration by up to 5.9%.
Modelling long-term fire occurrence factors in Spain by accounting for local variations with geographically weighted regression
Authors: Martínez-Fernández J. , Chuvieco E. , Koutsias N.
Published: February 2013

Abstract. Humans are responsible for most forest fires in Europe, but anthropogenic factors behind these events are still poorly understood. We tried to identify the driving factors of human-caused fire occurrence in Spain by applying two different statistical approaches. Firstly, assuming stationary processes for the whole country, we created models based on multiple linear regression and binary logistic regression to find factors associated with fire density and fire presence, respectively. Secondly, we used geographically weighted regression (GWR) to better understand and explore the local and regional variations of those factors behind human-caused fire occurrence. The number of human-caused fires occurring within a 25-yr period (1983–2007) was computed for each of the 7638 Spanish mainland municipalities, creating a binary variable (fire/no fire) to develop logistic models, and a continuous variable (fire density) to build standard linear regression models. A total of 383 657 fires were registered in the study dataset. The binary logistic model, which estimates the probability of having/not having a fire, successfully classified 76.4% of the total observations, while the ordinary least squares (OLS) regression model explained 53% of the variation of the fire density patterns (adjusted R2 = 0.53). Both approaches confirmed, in addition to forest and climatic variables, the importance of variables related with agrarian activities, land abandonment, rural population exodus and developmental processes as underlying factors of fire occurrence. For the GWR approach, the explanatory power of the GW linear model for fire density using an adaptive bandwidth increased from 53% to 67%, while for the GW logistic model the correctly classified observations improved only slightly, from 76.4% to 78.4%, but significantly according to the corrected Akaike Information Criterion (AICc), from 3451.19 to 3321.19. The results from GWR indicated a significant spatial variation in the local parameter estimates for all the variables and an important reduction of the autocorrelation in the residuals of the GW linear model. Despite the fitting improvement of local models, GW regression, more than an alternative to "global" or traditional regression modelling, seems to be a valuable complement to explore the non-stationary relationships between the response variable and the explanatory variables. The synergy of global and local modelling provides insights into fire management and policy and helps further our understanding of the fire problem over large areas while at the same time recognizing its local character.
Borehole temperatures reveal a changed energy budget at Mill Island, East Antarctica, over recent decades
Authors: Roberts J. L. , Moy A. D. , van Ommen T. D. , Curran M. A. J. , Worby A. P. , Goodwin I. D. , Inoue M.
Published: February 2013

Abstract. A borehole temperature record from the Mill Island (East Antarctica) icecap reveals a large surface warming signal manifested as a 0.75 K temperature difference over the approximate 100 m depth in the zone of zero annual amplitude below the seasonally varying zone. The temperature profile shows a break in gradient around 49 m depth, which we model with inverse numerical simulations, indicating that surface warming started around the austral summer of 1980/81 AD ±5 yr. This warming of approximately 0.37 K per decade is consistent with trends seen in both instrumental and other reconstructions for Antarctica and, therefore, suggests that regional- rather than local-scale processes are largely responsible. Alteration of the surface energy budget arising from changes in radiation balances due to local cloud, the amount of liquid deposition and local air temperatures associated with altered air/sea exchanges also potentially plays a role at this location due to the proximity of the Shackleton Ice Shelf and sea-ice zone.
The Center Holds Quite Well: An Ethnographic Study of Social Structure and Control in Jehovah’s Witness Religious Organization
Authors: Trahan Adam
Published: February 2013

Religion has long occupied a singularly prominent position among the various institutions of social control. Evidence suggests, however, that the American religious milieu has changed in recent decades. Several historically fringe religions have grown in terms of power and influence while traditionally dominant religious institutions have deteriorated. One of the fastest growing religious organizations is Jehovah’s Witness. Despite its increasingly powerful role in American society, we know very little about how Jehovah’s Witness operates as a system of social control. This paper presents the findings of an ethnographic study of the mechanisms with which Jehovah’s Witness’ construct and control deviance. The results demonstrate that Jehovah’s Witness operates according to the principles of functional systems theory. Witnesses are isolated from other social systems, which are deemed evil, and those who stray are shamed and labeled. Growth is maintained through careful evangelism processes that minimize threats to the organization and socialize core values to willing participants.
Why sauropods had long necks; and why giraffes have short necks
Authors: Taylor Michael P. , Wedel Mathew J.
Published: February 2013

The necks of the sauropod dinosaurs reached 15 m in length: six times longer than that of the world record giraffe and five times longer than those of all other terrestrial animals. Several anatomical features enabled this extreme elongation, including: absolutely large body size and quadrupedal stance providing a stable platform for a long neck; a small, light head that did not orally process food; cervical vertebrae that were both numerous and individually elongate; an efficient air-sac-based respiratory system; and distinctive cervical architecture. Relevant features of sauropod cervical vertebrae include: pneumatic chambers that enabled the bone to be positioned in a mechanically efficient way within the envelope; and muscular attachments of varying importance to the neural spines, epipophyses and cervical ribs. Other long-necked tetrapods lacked important features of sauropods, preventing the evolution of longer necks: for example, giraffes have relatively small torsos and large, heavy heads, share the usual mammalian constraint of only seven cervical vertebrae, and lack an air-sac system and pneumatic bones. Among non-sauropods, their saurischian relatives the theropod dinosaurs seem to have been best placed to evolve long necks, and indeed their necks probably surpassed those of giraffes. But 150 million years of evolution did not suffice for them to exceed a relatively modest 2.5 m.