bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological ice nucleation particles in the urban atmosphere of two megacities Beijing and Tianjin in North China
Authors: Hu Wei , Huang Shu , Chen Jie , Chen Jingchuan , Pei Xiangyu , Wu Zhijun , Fu Pingqing
Published: March 2020

Biological materials are the most active ice nucleating particles (INPs), which can nucleate ice at relatively warm temperatures, affecting cloud properties and regional or even global climate. However, the understanding on the impact of biological INPs in urban areas is quite limited. Beijing is the biggest megacity in North China suffered from severe air pollution. Tianjin is the biggest coastal megacity in North China and influenced by both continental/anthropogenic pollution and marine air masses, especially in summer. In this study, we collected aerosol samples on the urban campuses of Tianjin University (39.11°N, 117.17°E) from 01 to 08 July 2019 and PeKing University (39.99°N, 116.31°E) from 11 to 18 August 2019 with SKC Biosamplers. The concentration of INPs in aerosols has been investigated using the PeKing University Ice Nucleation Array (PKU-INA). The abundance of total bacteria in aerosols was enumerated using the LIVE/DEAD bacterial viability assay and an epifluorescence microscope (DM2500, Leica, Germany). The average concentration of INPs in Beijing (18 ± 23 L-1) is higher than in Tianjin (8 ± 18 L-1) at -19 °C. Heat-sensitive INPs inactivated by heat treatment (inactivating ice nucleation protein, 95°C, 15 min) and lysozyme-sensitive INPs (digested by lysozyme) were inferred to biological INPs and bacterial INPs, respectively. The contribution of biological INPs in Beijing (86 ± 14%) was higher than in Tianjin (72 ± 26%), but the proportion of bacterial INPs in Beijing (57 ± 20%) was lower than in Tianjin (64 ± 22%). In addition, we measured the ice nucleation activity of ice nucleating macromolecules (INMs) in filtrate (0.22 µm) and after heat treatment. INMs can be found both in Tianjin and Beijing and the majority of them can be inactivated by heat treatment, indicating most of them were likely proteinaceous materials. Also, we found a significant increase in the concentration of INPs during a rain period with strong wind in Tianjin, which implies rainfall and wind speed may significantly influence the abundance of INPs in this region. Backward air masses trajectories indicated that continental air masses can bring high bacterial INPs in Tianjin and Beijing. Interestingly, the air masses in Tianjin with low bacterial INP concentration were mainly from marine areas. These results imply that biological sources including bacteria may contribute a large fraction of INPs above -19 °C in Tianjin and Beijing in the summer of 2019, and biological INPs potentially play an important role in cloud formation and precipitation in Chinese urban areas.
Comparison of uncertainty quantification methods on the example of soil organic carbon stock mapping in Hungary
Authors: Szatmári Gábor , Pásztor László
Published: March 2020

Digital soil mapping (DSM) aims to provide spatial soil information for a wide range of studies (e.g. agro-environmental management, nature conservation, rural development, water and food security etc.). For this purpose, advanced statistical methods are in use for inferring the spatial variations of soil. Nowadays, there is a heap of evidences that researchers and stakeholders are not just interested in the maps of soil properties, functions and/or services but in their uncertainties as well. This is indispensable to support decision making process. In DSM various uncertainty quantification methods are in use, however, only a few studies have addressed the issue of comparing them. In this study, we compared the suitability of several commonly applied digital soil mapping methods to quantify uncertainty with regard to a survey of soil organic carbon stock in Hungary. To fairly represent the wide range of DSM methods, the followings were selected: universal kriging (UK), sequential Gaussian simulation (SGS), random forest plus kriging (RFK) and quantile regression forest (QRF). For RFK two uncertainty quantification methods were adopted based on kriging variance (RFK-1) and bootstrapping (RFK-2). We used a control dataset consisting of 200 independent SOC stock observations for validating not just the spatial predictions but their uncertainty quantifications as well. For validating the uncertainty quantifications we applied accuracy plots (a.k.a. prediction interval coverage probability plots) and a modified version of G-statistics. According to our results, QRF and SGS provided the best quantifications of uncertainty. UK and RFK-2 overestimated whereas RFK-1 underestimated the uncertainty. Based on our results we could draw a conclusion that there is a need to validate the uncertainty quantifications before using them for decision making. Furthermore, special attention should be paid to the assumptions made in uncertainty quantification.

 

Acknowledgment: Our research was supported by the Hungarian National Research, Development and Innovation Office (NRDI; Grant No: KH126725) and the Premium Postdoctoral Scholarship of the Hungarian Academy of Sciences (PREMIUM-2019-390) (Gábor Szatmári).
Monitoring and performances evolutions of the 3 in-flight IASI instruments on-board METOP satellites
Authors: Le Barbier Laura , Faillot Mathilde , Jacquette Elsa , Buffet Laurence , Penquer Antoine , Vandermarcq Olivier , Tournier Bernard , Kanghah Yannick , Jouglet Denis , Vincensini Anais , Enache Silvia , Calvel Jean-Christophe , Andrianony Fy , Lalanne Tristan
Published: March 2020

The EUMETSAT Polar System (EPS) programme is composed of three polar orbiting meteorological METOP satellites. The main payload instrument on-board each METOP is an InfraRed Atmospheric Sounding Interferometer (IASI). METOP-A, the first one of this series, was launched in 2006. Then METOP-B and METOP-C were launched successively in 2012 and 2018. IASI instrument products are disseminated to meteorological institutions for numerical weather prediction, to laboratories for atmospheric and climate studies and also to space agencies for expertise and monitoring. Since their beginning of life, IASI on-board METOP-A and METOP-B continue to perform very well and therefore demonstrate IASI instrument great performances stability and its sturdiness over time. Since July 2019, IASI on-board METOP-C is operational. It will ensure the continuity of good calibrated data dissemination to the user community for the next decade.

The purpose of this paper is to present the current performances status of the 3 in-flight IASI instruments, up to the Level 1 data. The objective is to give a feedback on the validation and the monitoring performed on IASI instruments during its life time. Moreover, during the past few years, some operational improvements were applied like the update of the on-board non-linerity correction for the 3 instruments. The impact of this new correction will be presented, also the reprocessing of a huge amount of IASI-A data for climate series.

New improvements will be assessed, like the impact on the spectral calibration monitoring of the new release of the GEISA spectroscopic database and the 4A/OP atlases or improvements of inter-comparison techniques.
Poroelastic aspects in geothermics
Authors: Kretz Bianca , Freeden Willi , Michel Volker
Published: March 2020

The aspect of poroelasticity is anywhere interesting where a solid material and a fluid come into play and have an effect on each other. This is the case in many applications and we want to focus on geothermics. It is useful to consider this aspect since the replacement of the water in the reservoir below the Earth's surface has an effect on the sorrounding material and vice versa. The underlying physical processes can be described by partial differential equations, called the quasistatic equations of poroelasticity (QEP). From a mathematical point of view, we have a set of three (for two space and one time dimension) partial differential equations with the unknowns u (displacement) and p (pore pressure) depending on the space and the time.

Our aim is to do a decomposition of the data given for u and p in order that we can see underlying structures in the different decomposition scales that cannot be seen in the whole data.
For this process, we need the fundamental solution tensor of the QEP (cf. [1],[5]).
That means we assume that we have given data for u and p (they can be obtained for example by a method of fundamental solutions, cf. [1]) and want to investigate a post-processing method to these data. Here we follow the basic approaches for the Laplace-, Helmholtz- and d'Alembert equation (cf. [2],[4],[6]) and the  Cauchy-Navier equation as a tensor-valued ansatz (cf. [3]). That means we want to modify our elements of the fundamental solution tensor in such a way that we smooth the singularity concerning a parameter set τ=(τx,τt). 
With the help of these modified functions, we construct scaling functions which have to fulfil the properties of an approximate identity.
They are convolved with the given data to extract more details of u and p.

References

[1] M. Augustin: A method of fundamental solutions in poroelasticity to model the stress field in geothermal reservoirs, PhD Thesis, University of Kaiserslautern, 2015, Birkhäuser, New York, 2015.
[2] C. Blick, Multiscale potential methods in geothermal research: decorrelation reflected post-processing and locally based inversion, PhD Thesis, Geomathematics Group, Department of Mathematics, University of Kaiserslautern, 2015.
[3] C. Blick, S. Eberle, Multiscale density decorrelation by Cauchy-Navier wavelets, Int. J. Geomath. 10, 2019, article 24.
[4] C. Blick, W. Freeden, H. Nutz: Feature extraction of geological signatures by multiscale gravimetry. Int. J. Geomath. 8: 57-83, 2017.
[5] A.H.D. Cheng and E. Detournay: On singular integral equations and fundamental solutions of poroelasticity. Int. J. Solid. Struct. 35, 4521-4555, 1998.
[6] W. Freeden, C. Blick: Signal decorrelation by means of multiscale methods, World of Mining, 65(5):304-317, 2013.
Signature of supershear transition seen in damage and aftershock pattern
Authors: Bhat Harsha , Jara Jorge , Bruhat Lucile , Antoine Solene , Okubo Kurama , Thomas Marion , Rougier Esteban , Rosakis Ares , Sammis Charles , Klinger Yann , Jolivet Romain
Published: March 2020

Supershear earthquakes are rare but powerful ruptures with devastating consequences. How quickly an earthquake rupture attains this speed, or for that matter decelerates from it, strongly affects high-frequency ground motion and the spatial extent of coseismic off-fault damage. Traditionally, studies of supershear earthquakes have focused on determining which fault segments sustained fully-grown supershear ruptures. Knowing that the rupture first propagated at subshear rupture speeds, these studies usually guessed an approximate location for the transition from subshear to supershear regimes. The rarity of confirmed supershear ruptures, combined with the fact that conditions for supershear transition are still debated, complicates the investigation of supershear transition in real earthquakes. Here, we find a unique signature of the location of a supershear transition: we show that, when a rupture accelerates towards supershear speed, the stress concentration abruptly shrinks, limiting the off-fault damage and aftershock productivity. First, we use theoretical fracture mechanics to demonstrate that, before transitioning to supershear, the stress concentration around the rupture tip shrinks, confining the region where damage & aftershocks are expected. Then, employing two different dynamic rupture modeling approaches, we confirm such reduction in stress concentration, further validating the expected signature in the transition region. We contrast these numerical and theoretical results with high-resolution aftershock catalogs for three natural supershear earthquakes, where we identify a small region with lower aftershock density near the supershear transition. Finally, using satellite optical image correlation techniques, we show that, for a fourth event, the transition zone is characterized by a diminution in the width of the damage zone. Our results demonstrate that the transition from subshear to supershear rupture can be clearly identified by a localized absence of aftershocks, and a decrease in off-fault damage, due to a transient reduction of the stress intensity at the rupture tip.
Analysis of Geomagnetic Variability by Empirical Orthogonal Functions
Authors: Chung Chi-Hua , Chao Benjamin Fong
Published: March 2020

We examine the secular variations of global geomagnetic field on long temporal scales using the IGRF model given in Gauss coefficients for 1900 - 2020. We apply the Empirical Orthogonal Function (EOF) analysis to the geomagnetic field truncated at degree 6 and downward continue it to the core-mantle boundary (CMB) under the assumption of an insulating mantle. The first three EOF modes show the periods around 120, 75 and 60 years with corresponding spatial structures. These oscillational modes potentially support the manifestation of magnetic, Archimedes and Coriolis (MAC) waves in the stably stratified layer near CMB (Buffett, 2016). We also model and decompose the geomagnetic field to standing and drifting components according to trajectories of the Gauss coefficients similarly to Yukutake (2015). We then use the Complex EOF (CEOF) analysis on the drifting field. The results indicate the presence of the westward drift phenomenon but only weakly given the fact that the westward drift has only completed a fraction of a cycle during this time.
Towards more realistic values of elastic moduli for volcano modelling
Authors: Heap Michael , Villeneuve Marlène , Albino Fabien , Farquharson Jamie , Brothelande Elodie , Amelung Falk , Got Jean-Luc , Baud Patrick
Published: March 2020

The accuracy of elastic analytical solutions and numerical models, widely used in volcanology to interpret surface ground deformation, depends heavily on the Young’s modulus chosen to represent the medium. The paucity of laboratory studies that provide Young’s moduli for volcanic rocks, and studies that tackle the topic of upscaling these values to the relevant lengthscale, has left volcano modellers ill-equipped to select appropriate Young’s moduli for their models. Here we present a wealth of laboratory data and suggest tools, widely used in geotechnics but adapted here to better suit volcanic rocks, to upscale these values to the scale of a volcanic rock mass. We provide the means to estimate upscaled values of Young’s modulus, Poisson’s ratio, shear modulus, and bulk modulus for a volcanic rock mass that can be improved with laboratory measurements and/or structural assessments of the studied area, but do not rely on them. In the absence of information, we estimate upscaled values of Young’s modulus, Poisson’s ratio, shear modulus, and bulk modulus for volcanic rock with an average porosity and an average fracture density/quality to be 5.4 GPa, 0.3, 2.1 GPa, and 4.5 GPa, respectively. The proposed Young’s modulus for a typical volcanic rock mass of 5.4 GPa is much lower than the values typically used in volcano modelling. We also offer two methods to estimate depth-dependent rock mass Young’s moduli, and provide two examples, using published data from boreholes within Kīlauea volcano (USA) and Mt. Unzen (Japan), to demonstrate how to apply our approach to real datasets. It is our hope that our data and analysis will assist in the selection of elastic moduli for volcano modelling. To this end, our new publication (Heap et al., 2019), which outlines our approach in detail, also provides a Microsoft Excel© spreadsheet containing the data and necessary equations to calculate rock mass elastic moduli that can be updated when new data become available. The selection of the most appropriate elastic moduli will provide the most accurate model predictions and therefore the most reliable information regarding the unrest of a particular volcano or volcanic terrain.

Heap, M.J., Villeneuve, M., Albino, F., Farquharson, J.I., Brothelande, E., Amelung, F., Got, J.L. and Baud, P., 2019. Towards more realistic values of elastic moduli for volcano modelling. Journal of Volcanology and Geothermal Research, https://doi.org/10.1016/j.jvolgeores.2019.106684.
Data Management for Early Career Scientists – How to Tame the Elephant
Authors: Comas-Bru Laia , Schmidt Marcus
Published: March 2020

Data Management can be overwhelming, especially for Early Career Scientists. In order to give them a kick-start, the World Data System (WDS) organised a 3-day EGU-sponsored workshop on current achievements and future challenges in November 2019 in Paris. The purpose of the workshop was to provide Early Career Scientists with practical skills in data curation and management through a combination of practical sessions, group discussions and lectures. Participants were introduced to what are research data andcommon vocabulary to be used during the workshop. Later, a World Café session provided an opportunity to discuss individual challenges on data management and expectations of the workshop in small groups of peers. Lectures and discussions evolved around Open Science, Data Management Plans (DMP), data exchange, copyright and plagiarism, the use of Big Data, ontologies and cloud platforms in Science. Finally, the roles and responsibilities of the WDS as well as its WDS Early Career Researcher Network were discussed. Wrapping-up the workshop, attendees were walked through what is a data repository and how do they obtain their certifications.This PICO presentation given by two attendees of the workshop will showcase the main topics of discussion on data management and curation, provide key examples with special emphasis on the importance of creating a DMP at an early stage of your research project and share practical tools and advise on how to make data management more accessible.
Update on scales and energetics of auroral field-aligned currents as observed by Swarm
Authors: Pick Leonie , Vogt Joachim , Blagau Adrian , Stachlys Nele
Published: March 2020

Auroral field-aligned currents (FACs) are of key importance for the electromagnetic coupling and the energy transport in the magnetosphere-ionosphere system. We use Swarm multi-spacecraft magnetic and electric field measurements from a selection of auroral oval crossing events to advance our understanding of the spatial scales and the electromagnetic energy flux (Poynting flux) associated with sheets of auroral FACs. Our study comprises the derivation of a scale-dependent correlation function based on dual-satellite vectorial magnetic field perturbation time series, in order to identify and analyze planar current structures. Applying concepts from multi-point boundary crossing analysis to data from Swarm-A and Swarm-C, a correlation measure is constructed using the mean square deviation of the observed magnetic perturbations and an empirical pattern function. Peak correlations indicate the positions and the scales of auroral FAC sheets, which we contextualize with the magnetic local time, the geomagnetic latitude, and geomagnetic activity indices (e.g., AL). In a parallel strand of work, we estimate the associated Poynting flux from the combination of the magnetic field perturbations and those of the electric field as deduced from the observed cross-track ion drift velocity. We assess the quality of our Swarm-based estimate by a comparison to the Poynting flux given by the “Cosgrove-PF” empirical model, which is based on FAST data from 1996 to 2001 and available from NASA’s Community Coordinated Modeling Center. Connecting both strands of work, we check to what degree this data-model comparison depends on the current sheets’ spatial scale. Throughout the study, we adopt a framework for describing planar magnetic structures that facilitates error analysis and accommodates not only boundary analysis, but also single-spacecraft polarization techniques.
Traceability of real-time reference gas generation for reactive gaseous compounds
Authors: Rajamäki Timo , Saxholm Sari
Published: March 2020

For reactive gaseous compounds, limited availability of bottled standard gases often limits their measurement accuracy and comparability. Typically, an available reference gas concentration range for the specific compounds may be limited to even orders of magnitude higher than the levels normally measured at atmospheric measurements and most often only dry reference gases in inert matrices, typically nitrogen, are available. This means that when applying test gases from cylinders humidity in measurement system may cause significantly longer measurement response than in normal operation.

 

A real-time reference gas generation is an effective method to circumvent these obstacles. Controlled evaporation of the reference solution enables flexible and reliable generation of test gases in wide concentration and flow ranges as well as in different gas matrices. The method is useable in field conditions and it may provide cost savings since necessary consumables include solely pure carrier gas and solution of the studied chemical with know concentration.

 

We validate this method for different reactive gaseous compounds and key impurities. For mercury chloride, the most typical form of oxidised mercury in process emissions and atmosphere, reference gas with concentration ranging from sub-ng/m3 to tens of µg/m3 is generated. In case of typical base and acid trace impurities, ammonia, hydrogen chloride and hydrogen fluoride, the reference gases are generated in (bio-) methane and air matrices. In all cases studied, the stabilization time of generating gas flow is no longer, than some minutes. Accuracy and traceability of the generated gas concentration are estimated based on full uncertainty calculation as well as comparison with traceable reference gas standards.
The impact of land use change, climate change and reservoir construction on ecosystem services in a Mediterranean catchment
Authors: Eekhout Joris , Boix-Fayos Carolina , Pérez-Cutillas Pedro , de Vente Joris
Published: March 2020

The Mediterranean region has been identified as one of the most affected global hot-spots for climate change. Recent climate change in the Mediterranean can be characterized by faster increasing temperatures than the global mean and significant decreases in annual precipitation. Besides, important land cover changes have occurred, such as reforestation, agricultural intensification, urban expansion and the construction of many reservoirs, mainly with the purpose to store water for irrigation. Here we study the impacts of these changes on several ecosystem services in the Segura River catchment, a typical large Mediterranean catchment where many of the before mentioned changes have occurred in the last half century. We applied a hydrological model, coupled with a soil erosion and sediment transport model, to study the impact of climate and land cover change and reservoir construction on ecosystem services for the period 1971-2010. Eight ecosystem services indicators were defined, which include runoff, plant water stress, hillslope erosion, reservoir sediment yield, sediment concentration, reservoir storage, flood discharge and low flow. To assess larger land use changes, we also applied the model for an extended period (1952-2018) to the Taibilla subcatchment, a typical Mediterranean mountainous subcatchment, which plays an important role in the provision of water within the Segura River catchment. As main results we observed that climate change in the evaluated period is characterized by a decrease in precipitation and an increase in temperature. Detected land use change over the past 50 years is typical for many Mediterranean catchments. Natural vegetation in the headwaters increased due to agricultural land abandonment. Agriculture expanded in the central part of the catchment, which most likely is related to the construction of reservoirs in the same area. The downstream part of the catchment is characterized by urban expansion. While land use changed in more than 30% of the catchment, most impact on ecosystem services can be attributed to climate change and reservoir construction. All these changes have had positive and negative impacts on ecosystem services. The positive impacts include a decrease in hillslope erosion, sediment yield, sediment concentration and flood discharge (-21%, -18%, -82% and -41%, respectively). The negative impacts include an increase in plant water stress (+5%) and a decrease in reservoir storage (-5%). The decrease in low flow caused by land use change was counteracted by an increase in low flow due to reservoir construction. The results of our study highlight how relatively small climate and land use changes compared to the changes foreseen for the coming decades, have had an important impact on ecosystem services over the past 50 years.
Reconciling phase velocities from ambient noise and earthquake-generated surface waves by accounting for arrival-angle effects
Authors: Diaferia Giovanni , Cammarano Fabrizio , Boschi Lapo , Cammarano Fabio
Published: March 2020

The shear-wave velocities structure at depth can be unraveled from ambient noise (AN) as well as from earthquake-generated (EQ) surface waves. While the first approach mostly provides information at crustal scale, earthquake-based surface waves sense deeper structures due to their lower frequency content. However, for periods between 20 and 40 s, where the two methods often overlap, a number of studies have shown that phase velocities from EQ surface waves are systematically higher (~1%) than those retrieved from AN. The reason for such systematic bias is still debated; finite-frequency effects, overtone contamination, and off-path propagation of surface waves due to structural inhomogeneities have all been invoked as possible explanations of the discrepancy in question.

We explore the validity of the latter hypothesis, by correcting Rayleigh-wave phase velocities for the effect of off-path arrivals at two stations. The deviation from the theoretical path is estimated by evaluating the resemblance of the vertical with the π/2-shifted radial component of the recorded seismograms. We developed a two-station algorithm implementing such a correction and tested it on a dataset of seismograms collected from more than 350 stations recording 443 earthquake events from 2005 to 2019. We demonstrate that by compensating for the arrival-angle effects, the discrepancy between the two methods is significantly reduced. This result suggests that the off-path propagation between epicenters and receivers due to lateral inhomogeneity in the Earth's structure explains most of the discrepancy between AN and EQ phase velocities previously reported in the literature. Such improvement in determining Rayleigh phase velocities will lead to more reliable seismic tomographies and enhanced interpretations of seismic anomalies in terms of thermo-chemical characteristics.
Earthquake preferred days in the Lake Baikal and Yunnan-Sichuan Regions
Authors: Kossobokov Vladimir , Schepalina Polina , Nekrasova Anastasia
Published: March 2020

Understanding the cyclic and other forces governing geodynamics may provide fundamental clues for unraveling characteristics of earthquakes occurrence, which remains spectacular evidence induced by plate tectonics fueled by tidal drag and associated global cooling of the Earth (Riguzzi et al., 2010; Doglioni and Panza, 2015).

To check the hypotheses of earthquake-preferred days the nonparametric Kuiper test statistics for cyclic variations applied to the seismic evidence resulting from the empirical distributions of the earthquake origin time versus solar (Julian Day, JD) or lunar (Moon Phase, MP) cycles. We present the results of the Kuiper test application to seismicity of the Lake Baikal and Yúnnán-Sichuan Regions aimed at verification on a solid statistical base the hypotheses of uniform distribution of earthquake origin time JD’s and MP’s in respect to the earthquake magnitude cut-off.
Mixing States of Aerosol Particles in Urban Haze
Authors: Yang Shuo , Alpert Peter , Xu Yunzhi , Duan Fengkui , He Kebin , Ammann Markus
Published: March 2020

Secondary organic aerosols (SOA) are a large fraction of PM2.5 mass and contribute to extreme haze events, reducing visibility and impairing human health, especially in the Northern China Plain. It has been observed that laboratory generated and field collected SOA material can undergo liquid-liquid phase separation (LLPS), however this has never been directly observed in single ambient aerosol particles. Oligomers are a significant component of atmospheric SOA typically having a molecular mass of >200 g mol-1. These large molecules can be produced via multiphase chemical processes and, when soluble in the aerosol phase, may lead to interesting phase separation behavior.

We conducted a campaign in Beijing during which PM2.5 was analyzed using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) to observe oligomers at significant quantities. Aerosol particle samples collected before, during and at the peak of a pollution event were targeted. We have evidence that oligomers were the result of multiphase chemistry at high relative humidity. Single particles were probed for chemical morphology and mixing states using X-ray spectro-microscopy to characterize the numbers of particles mixed with inorganic matter, organic matter or soot. Using an environmental microchamber, we subjected single ambient particles to humidity cycles and observed any LLPS to occur. We also quantify the humidity required for LLPS to occur. Our data links oligomeric material having different solubility than e.g. inorganic hygroscopic components with LLPS, giving rise to a clear constraint for urban haze. The results will give statistically significant information about particle mixing state for aerosol population having different oligomer content, humidity history, LLPS behavior and pollution levels.
Hydraulic characterization of a karstic limestone vadose zone based on multi-methods geophysical measurements and lab testing
Authors: Jodry Clara , Mallet Céline , Deparis Jacques , Ammor Salma , Baltassat Jean-Michel , Azaroual Mohamed
Published: March 2020

The vadose zone (VZ) is a highly heterogeneous and dynamic system that have a huge impact on fluid flows and heat transfer, from the soil to the saturated zone. In order to characterize flow patterns within the vadose zone, a comprehensive knowledge of spatial hydraulic parameters distribution is necessary. In this matter, geophysical techniques have proven to be efficient, providing various physical parameters and imaging of the underground. Nonetheless, these techniques are mainly used for water-saturated media and an appropriate calibration of the standard petrophysical relationships is necessary for VZ.

This study is carried out in the framework of the implementation, in an agricultural field, of the platform “Observatory of Transfers in the Vadose Zone” (O-ZNS, Centre – Val de Loire, France). The O-ZNS aims to understand and quantify mass and heat transfers in the VZ thanks to an exceptional well (depth – 20 m and diameter – 4m) associated with boreholes dedicated to geophysical measurements and instrumented piezometers. The emphasis is put on developing high-resolution investigations and focused monitoring techniques and sensors for the vadose zone. This observatory offers a unique support to study and establish the relationships to convert physical responses into hydraulic parameters, especially water content, in the VZ of a limestone aquifer.

The geophysical field investigations, conducted prior to the digging of the well, included various scales of observation with 3D Electrical Resistivity Imaging, 2D Magnetic Resonance tomography and crossholes Ground Penetrating Radar tomography. These highlighted three main lithological groups with a few meter-thick soil, a heterogeneous karstified limestone and a massive fractured limestone, all part of the same geological formation. The results put forth the importance of the karstified level heterogeneity on transfers’ behaviour in the VZ, highlighting the presence of clay lens and a disparate water content distribution.

Going further, laboratory investigations have been carried out using field cores in order to characterize the VZ of the Beauce Limestone aquifer. Laboratory analyses enable us to establish Topp’s, Archie’s and CRIM (Complex Refractive Index Model) empirical relations and model. The objective now is to link quantitatively these geophysical field measurements, primarily electrical conductivity and dielectric permittivity, to the medium’s hydraulic parameters (e.g., hydraulic conductivity, porosity, water content). Results from this analysis should bring valuable information on the hydrogeological behaviour of the aquifer system and underline the influence of the observation scales on the estimation of the hydraulic parameter values of the vadose zone.
Persistent millennial-scale links between North Pacific intermediate-water ventilation and North Atlantic Climate during the deglaciation and last glaciation
Authors: Zou Jianjun , Shi Xuefa , Zhu Aimei , Chang Yuan-Pin , Chen Min-Te , Gong Xun , Lembke-Jene Lester
Published: March 2020

The deep ocean carbon cycle, especially carbon sequestration and outgassing, is one of the mechanisms to explain variations in atmospheric CO2 concentrations on millennial and orbital timescales. However, the potential role of subtropical North Pacific subsurface waters in modulating atmospheric CO2 levels on millennial timescales is poorly constrained. Here, we investigate a suite of geochemical proxies in a sediment core from the northern and middle Okinawa Trough to understand variations in intermediate-water ventilation of the subtropical North Pacific over the last 50,000 years (50 ka). Our results suggest that enhanced mid-depth western subtropical North Pacific (WSTNP) sedimentary oxygenation occurred during cold intervals during the last deglaciation and last glaciation, while oxygenation decreased during the Bölling-Alleröd (B/A) and warm interstadials. The enhanced oxygenation during cold spells is linked to the intensified North Pacific Intermediate Water (NPIW), while interglacial increase after 8.5 ka is linked to an intensification of the Kuroshio Current due to strengthened northeast trade winds over the tropics. The enhanced formation of NPIW during Heinrich Stadials was likely driven by the perturbation of sea ice formation and sea surface salinity oscillations in high-latitude North Pacific. The diminished sedimentary oxygenation during the B/A and interstadials due to decreased NPIW formation and enhanced export production, indicates an expansion of oxygen minimum zone in the North Pacific and enhanced CO2 sequestration at mid-depth waters. We attribute the millennial-scale changes to intensified NPIW and enhanced abyss flushing during deglacial cold and warm intervals, respectively, closely related to variations in North Atlantic Deep Water formation. Out study extends the millennial-scale links between ventilation in the subtropical North Pacific Ocean and the Atlantic Climate into the last glaciations, highlighting the key roles of Atlantic Meridional Overturning Circulation in regulating the North Pacific environment at millennial timescales. Note: Financial support was provided by the National Program on Global Change and Air-Sea Interaction (GASI-GEOGE-04) and by the National Natural Science Foundation of China (Grant Nos.: 41876065, 41476056, and U1606401).
A general BEST method predicting soil hydraulic parameters for any type of water retention and hydraulic conductivity curves
Authors: Fernández-Gálvez Jesús , Pollacco Joseph , Lassabatere Laurent , Angulo-Jaramillo Rafael , Carrick Sam
Published: March 2020

Soil hydraulic characterization is crucial to describe the retention and transport of water in soil, but current methodologies limit its spatial applicability. This work presents a cost-effective general Beerkan Estimation of Soil Transfer parameters (BEST) methodology using single ring infiltration experiments to derive soil hydraulic parameters for any type of unimodal water retention and hydraulic conductivity functions. The proposed method relies on the BEST approach. The novelty lies in the use of Kosugi hydraulic parameters without need for textural information. Kosugi functions were chosen because they are based on physical principles (log-normal distribution for pore size distributions). A link between the Kosugi parameters (i.e., relationship between σ and hkg) was introduced to reduce the number of parameters estimated and to avoid the need for information on the soil texture. This simplifies the procedures and avoids sources of errors related to the use of pedotransfer functions as for the previous BEST methods. Lastly, the method uses a quasi-exact formulation that is valid for all times, instead of the approximate expansions previously used, avoiding related inaccuracy and allowing the use of any infiltration data encompassing or not both transient and steady states. The new BEST methods were tested against numerically generated data for several contrasting synthetic soils, and the results show that these methods provide consistent hydraulic functions close to the target functions. The new BEST method is accurate and can use any type of water retention and hydraulic conductivity functions (Fernández-Gálvez et al., 2019).

 

 

Reference

Fernández-Gálvez, J., Pollacco, J.A.P., Lassabatere, L., Angulo-Jaramillo, R., Carrick, S., 2019. A general Beerkan Estimation of Soil Transfer parameters method predicting hydraulic parameters of any unimodal water retention and hydraulic conductivity curves: Application to the Kosugi soil hydraulic model without using particle size distribution data. Adv. Water Resour. 129, 118–130. https://doi.org/10.1016/j.advwatres.2019.05.005
Effect of Dissolved CO2 in Acid Mine Drainage on Sludge Composition
Authors: Yim Giljae , Cheong Youngwook , Lee Joonhak , Cho Sanghyun , Ji Wonhyun
Published: March 2020

Among the variables affecting the volume and composition sludge generated in the semi-active mine drainage treatment facility operating in Korea, the effect of CO2 dissolved in the mine drainage on the sludge composition was studied.

The water quality change was analyzed by neutralizing 1m3 of mine drainage from the Ilkwang abandoned mine. The neutralization with lime slurry resulted in removal of Fe, Al, Cu and SiO2, and an increase in Ca content in neutralized water. The dissolved CO2 in raw water was 56 mg/L but decreased to <1 mg/L after neutralization. The dissolved CO2 in the mine drainage can be consumed to form calcite or be removed by degassing before neutralization. There is also a possibility that gypsum may be produced depending on pH due to the high concentration of Ca and SO4 enriched.

The amount of sludge generated through the neutralization test was insufficient for analysis. Therefore, chemical analysis and mineral assessment were performed on the effluent, sludge and cakes generated in the settling pond in the Ilkwang abandoned mine. XRD analysis showed that calcite (CaCO3) and Bassanite (CaSO4 · H2O) were commonly found in red and white sludge. CO2 in the mine drainage reacted with CaO to affect the sludge composition. As a result of the XRF, white sludge contained 35.57% of CaO, indicating that a large amount of slaked lime was included. Red sludge and cakes had a Fe2O3 content of more than 35%, so iron was the main ingredient. In addition, the CaO content was analyzed as 15.28%, the second major component. As a result of measuring the paste pH of the dehydrated cake, it can be seen that the pH is in the range of 9 to 10 due to CaO. The sludge shows strong alkali characteristics, indicating that slaked lime remains in the sludge. The remaining slaked lime will increase the sludge volume and increase the sludge management costs.
Building Damage Information Extraction From Fully Polarimetric SAR Images Based on Variogram Texture Feature
Authors: Zhai Wei , Xiao Xiu-lai , Zhang Hao-ran
Published: March 2020

Rapid evaluation of building earthquake disaster information is of great significance for earthquake emergency rescue. Although polarimetric SAR has rich polarimetric information, there are still clear texture information in polarimetric SAR that could not be ignored, especially the intact artificial buildings show regular texture features in the image, and the texture distribution in the collapsed building area is disordered, so combining the texture information can also extract the building information well. In this paper, the full polarization SAR data of Yushu area in 2010 is taken as the research object, and the building area in SAR image is extracted by using the volume scattering component PV in Yamaguchi decomposition. On this basis, the intact building area and collapsed building area are extracted based on the variogram value. Comparing and analyzing the result with the intact building area is extracted by using the secondary scattering component PD in Yamaguchi decomposition. Finally, verified the accuracy by combing the optical remote sensing image after the earthquake, the extraction accuracy of intact buildings is 80.18%, collapsed buildings is 84.54%, and road water system is 77.58%.

Firstly, buildings and non-buildings are distinguished in SAR image. 100 sample matrixes are selected in building area and non-building area on PV component image respectively. After calculating the mean value of sample matrixes, the threshold values of building and non-building area are obtained based on the minimum error, and the building area and non-building area are extracted respectively according to the threshold values. Secondly, in the building area, the sample matrix of intact buildings and collapsed buildings is selected to calculate the variograms value, and then the variograms curve is drawn. When the range a = 11, the variograms value of the building area is calculated, and the FCM algorithm is used to extract the calculation results of intact buildings and collapsed buildings respectively; In order to compare and analyze the classification results, based on PD component, use K-means algorithm to extract intact buildings and the collapsed building areas are extracted separately, and the results are compared with the results based on the variogram texture feature method. Finally, the intact buildings and collapsed buildings extracted are calibrated and the extraction accuracy is calculated by combining the Google Earth historical image.

At the end of this paper, the shortcomings of extraction results based on Yamaguchi four component decomposition method and variogram method are discussed, and the idea of combining geographic information data to further improve the accuracy of earthquake damage assessment is proposed.
Radar-based characterization of heavy precipitation in the eastern Mediterranean and its representation in a convection-permitting model
Authors: Morin Efrat , Armon Moshe , Marra Francesco , Enzel Yehouda , Rostkier-Edelstein Dorita
Published: March 2020

Heavy precipitation events (HPEs) can lead to natural hazards (floods, debris flows) and contribute to water resources. Spatiotemporal rainfall patterns govern the hydrological, geomorphological and societal effects of HPEs. Thus, a correct characterization and prediction of rainfall patterns is crucial for coping with these events. However, information from rain gauges suitable for these goals is generally limited due to the sparseness of the networks, especially in the presence of sharp climatic gradients and small precipitating systems. Forecasting HPEs depends on the ability of weather models to generate credible rainfall patterns. In this study we characterize rainfall patterns during HPEs based on high-resolution weather radar data and evaluate the performance of a high-resolution (1 km2), convection-permitting Weather Research and Forecasting (WRF) model in simulating these patterns. We identified 41 HPEs in the eastern Mediterranean from a 24-year long radar record using local thresholds based on quantiles for different durations, classified these events into two synoptic systems, and ran model simulations for them. For most durations, HPEs near the coastline were characterized by the highest rain intensities; however, for short storm durations, the highest rain intensities were characterized for the inland desert. During the rainy season, center of mass of the rain field progresses from the sea inland. Rainfall during HPEs is highly localized in both space (<10 km decorrelation distance) and time (<5 min). WRF model simulations accurately generate the structure and location of the rain fields in 39 out of 41 HPEs. However, they showed a positive bias relative to the radar estimates and exhibited errors in the spatial location of the heaviest precipitation. Our results indicate that convection-permitting model outputs can provide reliable climatological analyses of heavy precipitation patterns; conversely, flood forecasting requires the use of ensemble simulations to overcome the spatial location errors.
Decrypting the sources of dissolved inorganic carbon in river water: Isotopic study from river Ganga, India
Authors: Kumar Anurag , Sanyal Prasanta
Published: March 2020

Freshwater flux transport large amount of carbon (dissolved and particulate, organic and inorganic) from the continent into the ocean, contributing significantly to the global carbon cycle. The present sources and sinks of natural as well as anthropogenically produced C compounds in the global carbon cycle remain enigmatic. Among the carbon sources in the river ecosystem, the dissolved inorganic carbon (DIC) constitutes a major component of carbon influx from land to ocean. These fluxes are significantly influenced by the terrestrial and estuary processes. The isotopic composition of DIC can be used to understand the sources and cycling of carbon in rivers and estuaries. In this study, δ13C values of DIC in river water of Ganga have been used to understand the sources of dissolved inorganic carbon into the river. The river Ganga (2500 km) is the largest river of the Indian subcontinent which originates from the Gangotri glacier and drains into the Bay of Bengal through its vast delta in the Sunderban. The Ganga river basin (GRB) covers an area of 106 km2 draining the carbon sources of the entire basin into the mainstream of river Ganga. The river transports nearly 0.2% of the global freshwater flux, 1% of global DIC flux and 5% of the global sediment flux into the ocean. Despite its significant importance to the global carbon transport, the understanding of the DIC sources in the complex Ganga river system remains enigmatic. Therefore to elucidate the carbon sources in the river Ganga, the δ13C DIC of river water were measured from source (Gomukh) to sink (Bay of Bengal) of the river Ganga for pre and late-monsoon period. The seasonal variation in the δ13C DIC shows enriched isotopic values in pre-monsoon compared to late-monsoon samples. The upper, middle and lower stretch of the river shows distinct enrichment factors for pre and late-monsoon samples. The variation in the δ13C DIC of river water might be indicating the DIC signature of the source water. The pre-monsoon samples show enrichment in the δ13C DIC values as we move downstream of the river, whereas the late-monsoon samples show a slight depletion trend. The difference between the pre and late- monsoon samples might be indicating the high input of soil CO2 during the late-monsoon season which is characterized by lower δ13C values.