bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrosion Behavior and Safety Analysis of 80S Steel in H2S/CO2 Environment
Authors: Zhang Yong Qiang , Yang Zhi Gang , Gao Rui Min , Liu Li , Yin Zhi Fu , Ta Chuan
Published: February 2019

Cost factors must be considered in the development of Yan'an gas field. In order to evaluate the applicability of economical 80S steel in the sulfur gas reservoir environment of Yan'an gas field, the indoor corrosion test was conducted to evaluate the resistance of 80S steel to uniform corrosion and SCC resistance in CO2/H2S coexisting corrosion environment, and combined with relevant standards. The security was analyzed. The results show that the uniform corrosion rate of 80S steel is the largest at 50 °C, and it decreases first and then increases with the increase of temperature. When the loading stress is 496.8MPa (552MPa×90%),the test duration was 720h. One sample cracked and the other two parallel samples did not cracked Comprehensive anti-uniform corrosion performance and anti-SCC performance, it is believed that 80S steel has certain risks in the corrosive environment of Yan'an gas field. It needs to cooperate with other anti-corrosion measures and monitor the service of the well string at any time.
Combination Application Strategy of Non-Metal Compound Pipe and its Verification
Authors: Zhang Yong Qiang , Liu Li , Yang Zhi Gang , Ta Chuan
Published: February 2019

The service environment of Yanchang oilfield was researched. The corrosion environment of the oil and gas area of Yanchang group is different, the summer rainstorm is frequent and the landslide debris flow is easy to occur. The theoretical analysis and pilot test of pipeline performance have been carried out. We suggest that the steel pipeline, t FRP pipeline and the flexible composite pipe for high pressure transmission can be used in Yanchang group. The combined application strategy of steel pipeline, FRP pipeline and flexible composite pipe for high pressure transmission was proposed and verified. The results show that the combined application strategy effectively slows down the pipeline corrosion problem, reduces pipeline leakage accidents caused by accidental landslides, and reduces environmental pollution accidents caused by accidents such as pipeline corrosion and leakage. The tracking and analysis of pipeline combined application strategy for up to 5 years, the results show that the pipeline combined application strategy is more economical. It is concluded that the combined application strategy of steel pipelines, FRP pipelines and Flexible Composite Pipe for High Pressure Transmissions can ensure smooth operation of pipelines and save costs in the development of oil and gas fields, and it is recommended to popularize.
Influence of Heterogeneous Reservoirs with Different Depths on Casing Deformation in Fuling Area
Authors: Ma Nan , Li Jun
Published: February 2019

In shale gas horizontal well fracturing operations, casing deformation and cement ring damage occur mostly in heterogeneous formations. Based on the characteristics of shale gas reservoirs in China and related literatures, this paper establishes a finite element model of heterogeneous stratum for the Fuling shale gas field and studies the effects of heterogeneity on casing deformation at different depths. In the heterogeneous stratigraphic model, the effects of shallow reservoir heterogeneity and deep reservoir heterogeneity on casing deformation were analyzed. The results show that the shallow reservoir heterogeneity and deep reservoir heterogeneity affect the casing deformation in different aspects; the stress that is subjected to casing in the shallow reservoir is greater than casing in the deep reservoir; at the lithological interface, the abrupt of stress change in the deep reservoir is significantly larger than that in the shallow reservoir. This conclusion is also applicable to other shale gas fields in China; In the development of shale gas resources, the shallow reservoirs should focus on the overall strength design of casings, the deep reservoirs should focus on the strength design of casings at lithological interface points.
Status and Influence of Shale Gas Well Integrity Failure
Authors: Zhai Wen Bao , Li Jun , Xi Yan , Liu Gong Hui , Zhou Ying Сao
Published: February 2019

The well integrity issues in oil and gas wells have a long history, especially in the shale gas development, which has a direct impact on improving single well production of shale gas horizontal wells. Reviewing the domestic and foreign literature researches, the development status of major shale gas blocks at home and abroad were introduced. Well integrity failure characteristics of major shale gas blocks at home and abroad were counted and analyzed in detail. Finally, considering the shale gas development blocks in China as an example, the structural integrity (casing deformation) and seal integrity (Sustained Casing/Annulus pressure, SCP/SAP) were analyzed by clarifying the failure mechanism that well integrity issues affected shale gas production and that shale gas well integrity issues in China are a new problem was thought. The failure mechanism of shale gas well integrity needs to be further clarified, and a complete set of failure prediction and control methods has not yet been formed. Therefore, based on the concept of shale gas geology-engineering integration, taking into account the actual conditions of shale gas development blocks, it is proposed to scientifically and reasonably study shale gas well integrity failure mechanisms and their control methods, which has a reference and guidance to improve shale gas development.
The Erosion-Corrosion Behaviors of the Full-Scale PFF78-70 Flat Valve and P110SS Tubing
Authors: Zhu Li Juan , Feng Chun , Yang Shang Yu , Han Li Hong , Yuan Jun Tao , Lu Cai Hong , Wang Hang , Lv Nai Xin
Published: February 2019

In the present work, a self-built device called “full scale tubular goods erosion-corrosion test system” was used to test the P110SS tubing with a total length of 10 m and a full scale PFF78-70 flat valve to study their erosion-corrosion behaviors in the acceleration simulation operating condition of a well in Sichuang oil field of China. The erosion-corrosion performance of the specimen was investigated by KH-7700 digital microscope, scanning electron microscopy (SEM), X-ray power diffraction (XRD) and energy-dispersive spectroscopy (EDS). The results indicated that the P110SS tubing suffered catastrophic erosion-corrosion; the maximum pitting corrosion rate of the P110SS in the gas phase fluid was 5.29mm/a; while that in the liquid phase fluid was 11.13mm/a; A double-layer corrosion products scale, inner FeCO3 layer and outer mixture layer mainly dominated by FeO, Fe3O4, Fe2O3 and FeO(OH), formed on the P110SS tubing. Erosion-corrosion only occurred in the stress concentration area of the valve plate hole of the PFF78-70 plate valve, and the size of the corrosion pits is about 0.5mm.
Experimental Analysis on Mechanical Properties of Perforated Casing in Complex Fracturing
Authors: Han Li Hong , Liu Guang Xi , Yang Shang Yu , Wang Peng
Published: February 2019

For unconventional oil and gas well perforating technology, field complex fracturing process to carry out the casing perforation physical simulation test, determine the different perforating process corresponding to the aperture size morphology, based on this, according to the physical simulation test results, perforating casing finite element model is established, the analysis of stress concentration around the perforation under different construction conditions, determine the outer extrusion safety factor, for complex oil and gas field casing string design and provide technical support. Keywords: complex fracturing;perforation; casing; mechanical properties
Multi-Scale Microstructure Regulation Technology of Near-α High Temperature Titanium Alloy
Authors: Qiao Xu , Li Bo Long , Wang Tong Bo , Nie Zuo Ren
Published: February 2019

The served harsh environment of advanced aircraft engine puts forward higher requirements for high temperature titanium alloy performance. The optimized heat treatment technology provides effective theoretical basis for improving the microstructure and properties of high temperature titanium alloys. In this paper, we study the influence of different heat treatment systems on microstructure and mechanical properties of high temperature alloy with equiaxed structure, in order to obtain the corresponding relationship between the process and the microstructure performance of the alloy and the optimal heat treatment process. Analysis the effect of solution treatment on the primary α phase quantitatively by optical microscope and Image-Pro-Plus 6.0 software based on the forged high temperature titanium alloy in α+β phase region. Observe the precipitation of α2 phase and silicide by TEM, optimize the aging process according to hardness test. The results show that the content of primary a phase decrease from 63.3% at 920°C to 15.3% at 990°C with the increase of solution temperature. When the temperature rises to 980~990°C, the structure changes from equiaxed structure to α+β duplex microstructure. And change into lamellar structure when the solution temperature raise to 1010°C. The secondary α phase precipitates more fully when the aging temperature increases. And with increasing aging time, the trend of α2 phase growth become more significantly. The optimum heat treatment system obtained in this experimental is 990°C/1h/AC+700°C/5h/AC, and the α phase is about 15.3%. Hence, the excellent microstructure and properties match has been obtained.
Application of 0.8 Design Factor in China Gas Pipeline
Authors: Wang Ke , Luo Jin Heng , Hui Wen Ying , Zhao Xin Wei , Ma Wei Feng , Huo Chun Yong
Published: February 2019

The paper reviews current situation of high design factor application abroad, and analyzes development of high-strength pipeline in China. It shows that related technology has greatly improved in China, such as manufacture of high strength pipe, inspection, quality control, pipeline construction and pipeline integrity management. So it is available to use 0.8 design factor for the class one location in China. And the paper also introduces trial section experiences in the third West-East pipeline on safety pre-assessment, design check, pipe specification, construction technology and integrity management plan. With relative specifications further perfected, it is promising to put the 0.8 design factor into a wide use in Chinese pipeline project.
Research on Drill Pipe’s Fatigue Life Prediction Based on Reliability
Authors: Li Fang Po
Published: February 2019

Fatigue life of drill pipe is studied systematically based on reliability analysis. Calculation results show that bending and tensile stress in drill pipe body is significantly greater than that in the tool joint during drilling process. Drill pipe body’s fatigue strength is about 500MPa under the condition that the stress ratio is -1. The fatigue strength of tool joint is about 360MPa under the condition that the average tensile stress is 496MPa. The fatigue fracture position of drill pipe is concentrated on pipe body, and most fatigue cracks originate from pipe’s outer surface. Compared with material fatigue life, the fatigue life of whole drill pipe is significantly lower. Under the condition that the confidence level is 95% and deviation is 5%, drill pipe’s fatigue life distribution is normal distribution while the stress amplitude is 660MPa, 620MPa, 580MPa and 540MPa respectively. With the decreasing of stress amplitude, the peak of logarithmic fatigue life’ probability density distribution curve decreases gradually, and its dispersion increases gradually. Drill pipe’s fatigue life prediction equations whose reliability are 50%, 90%, 99% and 99.9% are calculated separately.
Research on Design of Polycrystalline Diamond Composite Pendulum Wear-Resistant Belt
Authors: Wang Wei , Li Jun , Liu Gong Hui , Cha Chun Qing
Published: February 2019

The torque impactor can effectively solve the stick-slip vibration of PDC bit in the deep formation, but the wear of the pendulum seriously restricted the service life of the impactor. In order to reduce the wear of the pendulum under complicated working conditions, the polycrystalline diamond composite material was used as the wear-resistant material to design the pendulum wear-resistant belt. Based on the analysis of the feasibility of using polycrystalline diamond as pendulum wear-resistant material, the finite element model of dynamic contact interaction between pendulum wear-resistant belt and impact cylinder was established, the influence of the arrangement of wear-resistant blocks on the stress of the contact area between the pendulum wear-resistant belt and the impact cylinder was studied. The results show: Polycrystalline diamond composite material has stronger wear resistance and better anti-friction performance than conventional wear-resistant materials, and can reduce the wear of the inner wall of the impact cylinder, which is feasible on the surface of the pendulum hammer. The use of the wear-resistant belt structure is beneficial to improve the variation of the shear stress of the area where the pendulum and the impact cylinder contact each other. The wear-resistant belt structure is beneficial to improve the shear stress variation amplitude of the pendulum and impact cylinder in contact with each other. When the wear-resistant block is arranged in a circular block staggered arrangement, the shear stress change amplitude of the interaction contact area is the largest, the triangular block staggered arrangement mode is second, and the trough block shape staggered arrangement is the smallest. The research results have important reference significance for the design and application of polycrystalline diamond composite pendulum wear-resistant belt.
Efficacy of Chemokine Receptor Inhibition in Treating IL-36α–Induced Psoriasiform Inflammation
Authors: Campbell James J. , Ebsworth Karen , Ertl Linda S. , McMahon Jeffrey P. , Wang Yu , Yau Simon , Mali Venkat R. , Chhina Vicky , Kumamoto Alice , Liu Shirley , Dang Ton , Newland Dale , Charo Israel F. , Zhang Penglie , Schall Thomas J. , Singh Rajinder
Published: February 2019

Several types of psoriasiform dermatitis are associated with increased IL-36 cytokine activity in the skin. A rare, but severe, psoriasis-like disorder, generalized pustular psoriasis (GPP), is linked to loss-of-function mutations in the gene encoding IL-36RA, an important negative regulator of IL-36 signaling. To understand the effects of IL-36 dysregulation in a mouse model, we studied skin inflammation induced by intradermal injections of preactivated IL-36α. We found the immune cells infiltrating IL-36α–injected mouse skin to be of dramatically different composition than those infiltrating imiquimod-treated skin. The IL-36α–induced leukocyte population comprised nearly equal numbers of CD4+ αβ T cells, neutrophils, and inflammatory dendritic cells, whereas the imiquimod-induced population comprised γδ T cells and neutrophils. Ligands for chemokine receptors CCR6 and CXCR2 are increased in both GPP and IL-36α–treated skin, which led us to test an optimized small-molecule antagonist (CCX624) targeting CCR6 and CXCR2 in the IL-36α model. CCX624 significantly reduced the T cell, neutrophil, and inflammatory dendritic cell infiltrates and was more effective than saturating levels of an anti–IL-17RA mAb at reducing inflammatory symptoms. These findings put CCR6 and CXCR2 forward as novel targets for a mechanistically distinct therapeutic approach for inflammatory skin diseases involving dysregulated IL-36 signaling, such as GPP.
Representation and uniqueness for boundary value elliptic problems via first order systems
Authors: Auscher Pascal , Mourgoglou Mihalis
Published: February 2019

Given any elliptic system with

t

-independent coefficients in the upper-half space, we obtain representation and trace for the conormal gradient of solutions in the natural classes for the boundary value problems of Dirichlet and Neumann types with area integral control or non-tangential maximal control. The trace spaces are obtained in a natural range of boundary spaces which is parametrized by properties of some Hardy spaces. This implies a complete picture of uniqueness vs solvability and well-posedness.
Impact of humidity biases on light precipitation occurrence: observations versus simulations
Authors: Bastin Sophie , Drobinski Philippe , Chiriaco Marjolaine , Bock Olivier , Roehrig Romain , Gallardo Clemente , Conte Dario , Domínguez Alonso Marta , Li Laurent , Lionello Piero , Parracho Ana C.
Published: February 2019

Abstract. This work uses a network of GPS stations over Europe from which a homogenized
integrated water vapor (IWV) dataset has been retrieved, completed with
colocated temperature and precipitation measurements over specific stations
to (i) estimate the biases of six regional climate models over Europe in terms
of humidity; (ii) understand their origins; and (iii) finally assess the impact
of these biases on the frequency of occurrence of precipitation. The
evaluated simulations have been performed in the framework of
HYMEX/Med-CORDEX programs and cover the Mediterranean area and part of Europe
at horizontal resolutions of 50 to 12 km. The analysis shows that models tend to overestimate the low values of IWV
and the use of the nudging technique reduces the differences between GPS and
simulated IWV. Results suggest that physics of models mostly explain the
mean biases, while dynamics affects the variability. The land
surface–atmosphere exchanges affect the estimation of IWV over most part of
Europe, especially in summer. The limitations of the models to represent
these processes explain part of their biases in IWV. However, models
correctly simulate the dependance between IWV and temperature, and
specifically the deviation that this relationship experiences regarding the
Clausius–Clapeyron law after a critical value of temperature (Tbreak).
The high spatial variability of Tbreak indicates that it has a strong
dependence on local processes which drive the local humidity sources. This
explains why the maximum values of IWV are not necessarily observed over
warmer areas, which are often dry areas. Finally, it is shown over the SIRTA observatory (near Paris) that the frequency
of occurrence of light precipitation is strongly conditioned by the biases
in IWV and by the precision of the models to reproduce the distribution of
IWV as a function of the temperature. The results of the models indicate
that a similar dependence occurs in other areas of Europe, especially where
precipitation has a predominantly convective character. According to the
observations, for each range of temperature, there is a critical value of
IWV from which precipitation starts to increase. The critical values and the
probability of exceeding them are simulated with a bias that depends on the
model. Those models, which generally present light precipitation too often,
show lower critical values and higher probability of exceeding them.
Mesospheric semidiurnal tides and near-12-hour waves through jointly analyzing five longitudinally-distributed specular meteor radars at boreal midlatitudes
Authors: He Maosheng , Chau Jorge L.
Published: February 2019

Abstract. In the last decades, mesospheric tides have been intensively investigated with observations from both ground-based radars and satellites. Single-site radar observations provide continuous measurements at fixed locations without horizontal information whereas single spacecraft missions provide typically global coverage however with limited temporal coverage at a given location. In this work, combining eight years (2009–2016) of mesospheric winds collected by five specular meteor radars from three different longitudinal sectors at boreal midlatitudes (49 ± 8.5 °N), we develop an approach to investigate the most intense global-scale oscillation, namely, at the period T = 12 ± 0.5 hr. Resolved are six waves: the semidiurnal westward-traveling tidal modes with zonal wavenumber 1, 2, and 3 (SW1, SW2, SW3), the lunar semidiurnal tide M2, and the upper and lower sidebands (USB and LSB) of the 16-day wave nonlinear modulation on SW2. The temporal variations of the waves are studied statistically with a special focus on their responses to sudden stratospheric warming events (SSWs), and on their climatological seasonal variations. In response to SSWs, USB, LSB, and M2 enhance, while SW2 decreases. However, SW1 and SW3 do not respond noticeably to SSWs, contrary to the broadly-reported enhancements in the literature. The USB, LSB, and SW2 responses could be explained in terms of energy exchange through the nonlinear modulation, while LSB and USB might previously have been misinterpreted as SW1 and SW3, respectively. Besides, we find that LSB and M2 enhancements depend on the SSW classification with respect to the associated split or displacement of the polar vortex. In the case of seasonal variations, our results are qualitatively consistent with previous studies, and show a moderate correlation with an empirical tidal model derived from satellite observations.
Description of a formaldehyde retrieval algorithm for the Geostationary Environment Monitoring Spectrometer (GEMS)
Authors: Kwon Hyeong-Ahn , Park Rokjin J. , González Abad Gonzalo , Chance Kelly , Kurosu Thomas P. , Kim Jhoon , De Smedt Isabelle , Van Roozendael Michel , Peters Enno , Burrows John
Published: February 2019

Abstract. We describe a formaldehyde (HCHO) retrieval algorithm for the Geostationary Environment Monitoring Spectrometer (GEMS) that will be launched by the Korean Ministry of Environment in 2019. The algorithm comprises three steps: pre-processes, radiance fitting, and post-processes. The pre-processes include a wavelength calibration, and interpolation and convolution of absorption cross-sections; radiance fitting is conducted using a non-linear fitting method referred to as basic optical absorption spectroscopy (BOAS); and post-processes include air mass factor calculations and bias corrections for stripe patterns, background HCHO, and latitudinal biases. In this study, several sensitivity tests are conducted to examine the retrieval uncertainties using the GEMS HCHO algorithm. We evaluate the algorithm with the OMI Level 1B irradiance/radiance data by comparing our retrieved HCHO column densities with OMI HCHO products of the Smithsonian Astrophysical Observatory (OMHCHO) and the Belgian Institute for Space Aeronomy (OMI BIRA). Results show that OMI HCHO slant columns retrieved using the GEMS algorithm are in good agreement with OMHCHO, with correlation coefficients of 0.77–0.91 and regression slopes of 0.92–1.04 for March, June, September, and December 2005. Spatial distributions of HCHO slant columns from the GEMS algorithm are consistent with the OMI BIRA products, but have relatively poorer correlation coefficients of 0.52 to 0.76 compared to those against the OMHCHO products. Also, we compare the satellite results with ground-based MAX-DOAS observations. OMI GEMS HCHO vertical columns are by 0.8–30 % lower than those of MAX-DOAS at Haute-Provence Observatory (OHP) in France, Bremen in Germany, and Xianghe in China. We find that the OMI GEMS retrievals have less bias than the OMHCHO and OMI BIRA products for OHP and Bremen in comparison with MAX-DOAS.
Method to retrieve
cloud condensation nuclei number concentrations
using lidar
measurements
Authors: Tan Wangshu , Zhao Gang , Yu Yingli , Li Chengcai , Li Jian , Kang Ling , Zhu Tong , Zhao Chunsheng
Published: February 2019

Abstract. Determination of cloud condensation nuclei (CCN) number concentrations at cloud base is important to constrain aerosol-cloud interactions. A new method to retrieve CCN number concentrations using backscatter and extinction profiles from multiwavelength Raman lidars is proposed. The method implements hygroscopic enhancements of backscatter/extinction with relative humidity to derive dry backscatter/extinction and humidogram parameters. Humidogram parameters, Ångström exponents, and lidar extinction-to-backscatter ratios are then linked to the ratio of CCN number concentration to dry backscatter/extinction coefficient (ARξ). This linkage is established based on the datasets simulated by Mie theory and κ-Köhler theory with in situ measured particle size distributions and chemical compositions. CCN number concentration can thus be calculated with ARξ and dry backscatter/extinction. An independent theoretical simulated datasets is used to validate this new method and results show that the retrieved CCN number concentrations at supersaturations of 0.07 %, 0.10 %, and 0.20 % are in good agreement with theoretical calculated values. Sensitivity tests indicate that retrieval error in CCN arise mostly from uncertainties in extinction coefficients and RH profiles. The proposed method improves CCN retrieval from lidar measurements and has great potential in deriving scarce long-term CCN data at cloud base which benefits aerosol-cloud interaction studies.
NWP-based lightning prediction using flexible count data regression
Authors: Simon Thorsten , Mayr Georg J. , Umlauf Nikolaus , Zeileis Achim
Published: February 2019

Abstract. A method to predict lightning by postprocessing numerical weather prediction
(NWP) output is developed for the region of the European Eastern Alps.
Cloud-to-ground (CG) flashes – detected by the ground-based Austrian
Lightning Detection & Information System (ALDIS) network – are counted on
the 18×18 km2 grid of the 51-member NWP ensemble of the European
Centre for Medium-Range Weather Forecasts (ECMWF). These counts serve as the
target quantity in count data regression models for the occurrence of
lightning events and flash counts of CG. The probability of lightning
occurrence is modelled by a Bernoulli distribution. The flash counts are
modelled with a hurdle approach where the Bernoulli distribution is combined
with a zero-truncated negative binomial. In the statistical models the
parameters of the distributions are described by additive predictors, which
are assembled using potentially nonlinear functions of NWP covariates.
Measures of location and spread of 100 direct and derived NWP covariates
provide a pool of candidates for the nonlinear terms. A combination of
stability selection and gradient boosting identifies the nine (three) most
influential terms for the parameters of the Bernoulli (zero-truncated
negative binomial) distribution, most of which turn out to be associated with
either convective available potential energy (CAPE) or convective
precipitation. Markov chain Monte Carlo (MCMC) sampling estimates the final
model to provide credible inference of effects, scores, and
predictions. The selection of terms and MCMC sampling are applied for data of
the year 2016, and out-of-sample performance is evaluated for 2017. The
occurrence model outperforms a reference climatology – based on 7 years of
data – up to a forecast horizon of 5 days. The flash count model is
calibrated and also outperforms climatology for exceedance probabilities,
quantiles, and full predictive distributions.
Benthic alkalinity and DIC fluxes in the Rhône River prodelta generated by decoupled aerobic and anaerobic processes
Authors: Rassmann Jens , Eitel Eryn M. , Cathalot Cécile , Brandily Christophe , Lansard Bruno , Taillefert Martial , Rabouille Chrsitophe
Published: February 2019

Abstract. Estuarine regions are generally considered a net source of atmospheric CO2 as a result of the high organic carbon (OC) mineralization rates in the water column and their sediments. Yet, the intensity of anaerobic respiration processes in the sediments tempered by the reoxidation of reduced metabolites controls the net production of alkalinity from sediments that may partially buffer the metabolic CO2 generated by OC respiration. In this study, a benthic chamber was deployed in the Rhône River prodelta and the adjacent continental shelf (Gulf of Lions, NW Mediterranean) to assess the fluxes of total alkalinity (TA) and dissolved inorganic carbon (DIC) from the sediment. Concurrently, in situ O2 and pH microprofiles, electrochemical profiles, pore water and solid composition were measured in surface sediments to identify the main biogeochemical processes controlling the net production of alkalinity in these sediments. The benthic fluxes of TA and DIC, ranging between 14 and 74 mmol m−2 d−1 and 18 and 78 mmol m−2 d−1, respectively, were up to 8 times higher than the DOU fluxes (10.4 ± 0.9 mmol m−2 d−1) close to the river mouth, but their intensity decreased offshore, as a result of the decline in OC inputs. Low nitrate concentrations and strong pore water sulfate gradients indicated that the majority of the TA and DIC was produced by sulfate and iron reduction. Despite the complete removal of sulfate from the pore waters, dissolved sulfide concentrations were low due to the precipitation and burial of iron sulfide minerals (12.5 mmol m−2 d−1 near the river mouth), while soluble organic-Fe(III) complexes were concurrently found throughout the sediment column. The presence of organic-Fe(III) complexes together with low sulfide concentrations and high sulfate consumption suggests a dynamic system driven by the variability of the organic and inorganic particulate input originating from the river. By preventing reduced substances from being reoxidized, the precipitation and burial of iron sulfide decouples the iron and sulfur cycles from oxygen, therefore allowing a flux of alkalinity out of the sediments. In these conditions, the sediment provides a source of alkalinity to the bottom waters which mitigates the effect of the benthic DIC flux on the carbonate chemistry of coastal waters.
Permafrost distribution in steep slopes in Norway: measurements, statistical modelling and geomorphological implication
Authors: Magnin Florence , Etzelmüller Bernd , Westermann Sebastian , Isaksen Ketil , Hilger Paula , Hermanns Reginald L.
Published: February 2019

Abstract. Permafrost in steep slopes has been increasingly studied since the early 2000s in conjunction with a growing number of rock-slope failures, which likely resulted from permafrost degradation. In Norway, rock-slope destabilization is a widespread phenomenon and a major source of risk for the population and infrastructure. However, the lack of precise understanding of the permafrost distribution in steep slopes hinders the assessment of its role in these destabilizations. This study proposes the first nation-wide permafrost probability map for the steep slopes of Norway (CryoWall map). It is based on a multiple linear regression model fitted with multi-annual rock surface temperature (RST) measurements, collected at 25 rock-wall sites, spread across a latitudinal transect (59–69° N) over mainland Norway. The CryoWall map suggests that discontinuous permafrost widely occurs above 1300–1400 and 1600–1700 m a.s.l. in the north and south slopes of southern Norway (59° N), respectively. This lower altitudinal limit decreases in northern Norway (70° N) by about 500 ± 50 m, with more pronounced decrease for south faces, in reason of the insolation patterns largely driven by midnight sun in summer and polar night in winter. Similarly, the mean annual RST differences between north and south faces of similar elevation range around 1.5 °C in northern Norway and 3.5 °C in southern Norway. The CryoWall map is evaluated against direct ice observations in steep slopes and discussed in the context of former permafrost studies in various types of terrains in Norway. We show that permafrost can occur at much lower elevations in steep rock slopes than in other terrains, especially in north faces. We demonstrate that the CryoWall map is a valuable basis for further investigations related to permafrost in steep slopes in both practical concerns and fundamental science.
Detection and Explanation of Spatiotemporal Patterns in Late Cenozoic Palaeoclimate Change Relevant to Earth Surface Processes
Authors: Mutz Sebastian G. , Ehlers Todd A.
Published: February 2019

Abstract. Detecting and explaining differences between palaeoclimates can provide valuable insight into climatic tipping points and a useful framework of information for Earth scientists investigating processes that are affected by climate change over geological time. We apply a combination of multivariate cluster- and discriminant analysis techniques to a set of consistently set-up high-resolution palaeoclimate simulations conducted with the ECHAM5 climate model. A pre-industrial (PI) climate simulation serves as the control experiment, which is compared to a suite of simulations of Late Cenozoic climates, namely a Mid-Holocene (MH, ca. 6.5 ka), Last Glacial Maximum (LGM, ca. 21 ka) and Pliocene (PLIO, ca. 3 Ma) climate. For each of the study regions (Western South America, Europe and Himalaya–Tibet and South Alaska), differences in climate are subjected to geographical clustering to identify dominant modes of climate change and their spatial extent for each time slice comparison (PI-MH, PI-LGM and PI-PLIO). The selection of climate variables for the cluster analysis is made on the basis of their relevance to Earth surface processes and includes 2 m air temperature, 2 m air temperature amplitude, consecutive freezing days, freeze-thaw days, maximum precipitation, consecutive wet days, consecutive dry days, zonal wind speed and meridional wind speed. We then apply a two-class multivariate discriminant analysis to simulation pairs PI-MH, PI-LGM and PI-PLIO to evaluate and explain the discriminability between climates within each of the anomaly clusters. Changes in ice cover create the most distinct and stable patterns of climate change, and create the best discriminability between climates in western Patagonia. The distinct nature of European palaeoclimates is mostly explained by changes in 2 m air temperature (MH, LGM, PLIO), consecutive freezing days (LGM) and consecutive wet days (PLIO). These factors typically contribute 30 %–50 %, 10 %–40 % and 10 %–30 % respectively to climate discriminability. Finally, our results identify regions particularly prone to changes in precipitation-induced erosion and temperature-dependent physical weathering.
Systematic identification of external influences in multi-year microseismic recordings using convolutional neural networks
Authors: Meyer Matthias , Weber Samuel , Beutel Jan , Thiele Lothar
Published: February 2019

Abstract. Passive monitoring of ground motion can be used for geophysical process
analysis and natural hazard assessment. Detecting events in microseismic
signals can provide responsive insights into active geophysical processes.
However, in the raw signals, microseismic events are superimposed by external
influences, for example, anthropogenic or natural noise sources that distort
analysis results. In order to be able to perform event-based geophysical
analysis with such microseismic data records, it is imperative that negative
influence factors can be systematically and efficiently identified,
quantified and taken into account. Current identification methods (manual and
automatic) are subject to variable quality, inconsistencies or human errors.
Moreover, manual methods suffer from their inability to scale to increasing
data volumes, an important property when dealing with very large data volumes
as in the case of long-term monitoring. In this work, we present a systematic strategy to identify a multitude of
external influence sources, characterize and quantify their impact and
develop methods for automated identification in microseismic signals. We
apply the strategy developed to a real-world, multi-sensor, multi-year
microseismic monitoring experiment performed at the Matterhorn Hörnligrat
(Switzerland). We develop and present an approach based on convolutional
neural networks for microseismic data to detect external influences
originating in mountaineers, a major unwanted influence, with an error rate
of less than 1 %, 3 times lower than comparable algorithms. Moreover, we
present an ensemble classifier for the same task, obtaining an error rate of
0.79 % and an F1 score of 0.9383 by jointly using time-lapse image and
microseismic data on an annotated
subset of the monitoring data. Applying these classifiers to the whole
experimental dataset reveals that approximately one-fourth of events detected
by an event detector without such a preprocessing step are not due to seismic
activity but due to anthropogenic influences and that time periods with
mountaineer activity have a 9 times higher event rate. Due to these findings,
we argue that a systematic identification of external influences using a
semi-automated approach and machine learning techniques as presented in this
paper is a prerequisite for the qualitative and quantitative analysis of
long-term monitoring experiments.
Assessment of the Finite VolumE Sea Ice Ocean Model (FESOM2.0), Part I: Description of selected key model elements and comparison to its predecessor version
Authors: Scholz Patrick , Sidorenko Dmitry , Gurses Ozgur , Danilov Sergey , Koldunov Nikolay , Wang Qiang , Sein Dmitry , Smolentseva Margarita , Rakowsky Natalja , Jung Thomas
Published: February 2019

Abstract. The evaluation and model element description of the second version of the unstructured-mesh Finite-volumE Sea ice–Ocean circulation Model (FESOM2.0) is presented. The model sensitivity to arbitrary Lagrangian Eulerian (ALE) linear and nonlinear free surface formulation, Gent McWilliams eddy parameterisation, isoneutral Redi diffusion and different vertical mixing schemes is documented. The hydrographic biases, large scale circulation, numerical performance and scalability of FESOM2.0 are compared with its predecessor FESOM1.4. FESOM2.0 shows biases with a magnitude comparable to FESOM1.4 and it simulates a more realistic AMOC. Compared to its predecessor FESOM2.0 provides clearly defined fluxes and a three times higher throughput in terms of simulated years per day (SYPD). It is thus the first mature global unstructured-mesh ocean model with computational efficiency comparable to state-of-the-art structured-mesh ocean models. Other key elements of the model and new development will be described in following-up papers.
Beo v1.0: Numerical model of heat flow and low-temperature thermochronology in hydrothermal systems
Authors: Luijendijk Elco
Published: February 2019

Abstract. Low-temperature thermochronology can provide records of the thermal history of the upper crust and can be a valuable tool to quantify the history of hydrothermal systems. However, existing model codes of heat flow around hydrothermal systems do not include low-temperature thermochronology. Here I present a new model code that simulates thermal history around hydrothermal systems on geological timescales. The modelled thermal histories are used to calculate apatite (U-Th)/He (AHe) ages, which is a thermochronometer that is sensitive to temperatures up to 70 °C. The modelled AHe ages can be compared to measured values in surface outcrops or borehole samples to quantify the history of hydrothermal activity. Heat flux at the land surface is based on equations of latent and sensible heat flux, which allows more realistic land surface and spring temperatures than models that use simplified boundary conditions. Instead of simulating fully coupled fluid and heat flow, the code only simulates advective and conductive heat flow, with the rate of advective fluid flux specified by the user. This relatively simple setup is computationally efficient and allows running larger numbers of models to quantify model sensitivity and uncertainty. Example case studies demonstrate the sensitivity of hot spring temperatures to the depth, width and angle of permeable fault zones, and the effect of hydrothermal activity on AHe ages in surface outcrops and at depth.
The multiscale Routing Model mRM v1.0: simple river routing at resolutions from 1 to 50 km
Authors: Thober Stephan , Cuntz Matthias , Kelbling Matthias , Kumar Rohini , Mai Juliane , Samaniego Luis
Published: February 2019

Abstract. Routing streamflow through a river network is a fundamental requirement to verify lateral water fluxes simulated by hydrologic and land surface models. River routing is performed at diverse resolutions ranging from few kilometers to around 1°. The presented multiscale Routing Model mRM calculates streamflow at diverse spatial and temporal resolutions. mRM solves the kinematic wave equation using a finite difference scheme. An adaptive time stepping scheme fulfilling a numerical stability criteria is introduced in this study and compared against the original parametrization of mRM that has been developed within the mesoscale Hydrologic Model (mHM). mRM requires a high-resolution river network, which is upscaled internally to the desired spatial resolution. The user can change the spatial resolution by simply changing one number in the configuration file without any further adjustments of the input data. The performance of mRM is investigated on two datasets: a high-resolution German dataset and a slightly lower resolution European dataset. The adaptive time step scheme within mRM shows a remarkable scalability compared to its predecessor. Median Kling-Gupta efficiencies change less than 3 percent when the model parametrization is transferred from 3 to 48 km resolution. mRM also exhibits seamless scalability in time, providing identical results when forced with hourly and daily runoff. The streamflow calculated over the Danube catchment by the Regional Climate Model REMO coupled to mRM is comparable at 25 and 50 km resolution. The mRM source code is freely available and highly modular facilitating an easy internal coupling in existing Earth System Models.
Technical Note: On the confounding similarity of two water balance formulas – Turc-Mezentsev vs Tixeront-Fu
Authors: Andréassian Vazken , Sari Tewfik
Published: February 2019

Abstract. This Technical Note documents and analyzes the confounding similarity of two widely used water balance formulas: Turc-Mezentsev and Tixeront-Fu. It details their history, their hydrological and mathematical properties, and discusses the mathematical reasoning behind their slight differences. Apart from the difference identified in their partial differential expressions, both formulas share the same hydrological properties and it seems impossible to recommend one over the other as more hydrologically founded: hydrologists should feel free to choose the one they feel more comfortable with.
Improving hydrological projection performance under contrasting climatic conditions using spatial coherence through a hierarchical Bayesian regression framework
Authors: Pan Zhengke , Liu Pan , Gao Shida , Xia Jun , Chen Jie , Cheng Lei
Published: February 2019

Abstract. Understanding the projection performance of hydrological models under contrasting climatic conditions supports robust decision making, which highlights the need to adopt time-varying parameters in hydrological modeling to reduce the performance degradation. Many existing literatures model the time-varying parameters as functions of physically-based covariates; however, a major challenge remains finding effective information to control the large uncertainties that are linked to the additional parameters within the functions. This paper formulated the time-varying parameters for a lumped hydrological model as explicit functions of temporal covariates and used a hierarchical Bayesian (HB) framework to incorporate the spatial coherence of adjacent catchments to improve the robustness of the projection performance. Four modeling scenarios with different spatial coherence schemes, and one scenario with a stationary scheme for model parameters, were used to explore the transferability of hydrological models under contrasting climatic conditions. Three spatially adjacent catchments in southeast Australia were selected as case studies to examine validity of the proposed method. Results showed that (1) the time-varying function improved the model performance but also amplified the projection uncertainty compared with stationary setting of model parameters; (2) the proposed HB method successfully reduced the projection uncertainty and improved the robustness of model performance; and (3) model parameters calibrated over dry periods were not suitable for predicting runoff over wet periods because of a large degradation in projection performance. This study improves our understanding of the spatial coherence of time-varying parameters, which will help improve the projection performance under differing climatic conditions.
Study on Site Amplification Factor Correction for Earthquake Early Warning System
Authors: Xie Quancai , Ma Qiang , Zhang Jingfa , Yu Haiying
Published: February 2019

Abstract. The site amplification factor was usually considered as scalar values, such as amplification of peak ground acceleration or peak ground velocity, increments of seismic intensity in the conventional earthquake early warning system. This paper focus on evaluation of infinite impulse recursive filter method that could produce frequency-dependent site amplification and compare the performance of the scalar value method with the infinite impulse recursive filter method. Firstly, the strong motion data of IBRH10 and IBRH19 of Kiban Kyoshin network (Kik-net）from 2004 to 2012 were processed and selected carefully. The relative spectral ratio of IBRH10 surface acceleration to IBRH10 borehole acceleration, the relative spectral ratio of IBRH19 surface acceleration to IBRH19 borehole acceleration, the relative spectral ratio the IBRH10 surface and borehole acceleration to the IBRH19 surface and borehole acceleration were calculated using the traditional spectral ratio method. Secondly, the relative spectral ratio were modelled using the infinite impulse recursive filter method. The simulated IBRH19 surface acceleration and Fourier spectrum were obtained by filtering the IBRH19 borehole data. The seismic intensity residual were calculated for both the observation and simulation data, it shows that 98.6 % of these seismic intensity residuals are less than 0.5, 100 % of these seismic intensity residuals are less than 1. Similarly, the simulated IBRH10 Surface acceleration and Fourier spectrum were obtained by filtering the IBRH19 surface acceleration time series. The seismic intensity residual were calculated for both the observation data and the simulation data. The statistical data shows that 69.7 % of these seismic intensity residuals are less than 0.5, 98.1 % of these seismic intensity residuals are less than 1. Through these comparisons, we can find that these simulations show better performance than the ARV method and station correction method. It also shows good performance than the average level and the highest level of all the 11 years Japan Meteorological Agency (JMA) earthquake early warning system. Thirdly, compare different simulation cases, it can be easily found that this method could produce different amplification factor for different earthquakes. It could produce the frequency-depend site amplification factor. It highly improve the situation that the scalar value site amplification methods which could not produce different amplification factor for different earthquakes. This method pays attention to the amplitude and ignore the phase characteristic, this problem may be improved by the seismic interferometry method. This paper makes deep evaluation of the infinite impulse recursive filter method. Although there are some problems needed to consider carefully and solve, it shows good potential to be used in the future earthquake early warning systems for more accuracy modelling the site amplification factor.
"Timbeando en Nueva York": Cuban Timba Takes Root Abroad
Authors: Town Sarah
Published: February 2019

Timba came of age during Cuba’s 1990s economic crisis and soon traveled farther afield. In New York City today, diverse musicians reproduce, experiment with, and transform its sound with cover songs, new compositions, and reconfigured formats. This article examines three musical examples in ethnographic context, revealing tensions and overlap between local and cosmopolitan music practices, and sheds light on a popular dance culture that serves as the meeting ground for oral traditions and conservatory training. Through grounded and detailed investigation, it highlights blurred boundaries between musical practices, social spaces, and disciplinary approaches and explores their methodological and narrative implications.