bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Study on Spatial Correlation Characteristics of Tsunami Inundation Depth
Authors: Fukutani Yo
Published: March 2020

For a probabilistic tsunami risk assessment of multiple sites, it is important to consider the spatial correlation between tsunami inundation depth and the sites because it affects the aggregated probability distribution of site damages. Various uncertainties such as ground motion, building response characteristics, and material strength are considered in the probabilistic seismic risk assessment. However, any research that evaluates the spatial correlation characteristics of tsunamis is yet to be reported. In this study, we evaluate the macro spatial correlation coefficient of the tsunami inundation depth according to the relative distance in the tsunami run-up region. We firstly constructed the fault parameters of the Sagami trough earthquake which has a large slip off the Kanto area in Japan. The moment magnitude of the earthquake is 8.7, and there are 6,149 small faults. Using the initial water level calculated from the earthquake parameters as input data, we solved the continuous equation and 2D linear long wave equation, targeting Zushi city, Kanagawa Prefecture. The maximum tsunami inundation depth was 8.71 m. We regressed the exponential function (ρ(x) = aexp(bx) + cexp(dx)) for the relationship between the distance from the coastline and the tsunami inundation depth. As a result, we obtained an evaluation formula with a relatively high accuracy. The coefficient were a = 0.4555, b = −0.1653, c = 0.5434, d = −0.007345 and the determination coefficient was 0.992. The results of this study can be used for a probabilistic tsunami risk assessment for multiple sites.
Dynamic rupture and seismic radiation in a damage-breakage rheology model
Authors: Lyakhovsky Vladimir , Kurzon Ittai , Ben-Zion Yehuda
Published: March 2020

We present simulations of dynamic ruptures in a continuum damage-breakage rheological model and waves radiated by the ruptures observed in the far field. The model combines aspects of a continuum viscoelastic damage framework for brittle solids with a continuum breakage mechanics for granular flow. The brittle instability is associated with a phase transition between a damaged solid with distributed cracks and a granular medium within the generated rupture zone. The formulation significantly extends the ability to model brittle processes in structures with complex volumetric geometries and evolving elastic properties, compared to the traditional models of pre-existing frictional surface(s) in a solid with fixed properties. A set of numerical simulations examines the sensitivity of dynamic ruptures, seismic source properties and radiated waves to material properties controlling the coupled damage-breakage evolution, the thickness and geometry of the damage zone, and fluidity of the granular material. The simulations are performed in two stages. First, details of the rupture process are simulated using adaptive fine grid model. The results of these simulations include source parameters such as rupture velocity, potency, stress and strain drop, heat generation, and others. In the second stage, the obtained velocity source function is used for simulating radiated seismic waves and synthetic seismograms sampled by stations around the rupture zone and in the far field.

Detailed comparisons between the simulated source properties and those obtained by analyzing the synthetic seismograms demonstrate the relations between different source processes and inferred seismic parameters (potency, strain drop, directivity, rupture velocity, corner frequency, and others). One main effect shown in these simulations emphasizes the important role of rock damage and granulation process generating dynamic expansion-compaction around the process-zone. This expansion-compaction process leads to isotropic source term, while shear motion that accumulates behind the propagating front produces deviatoric deformation and shear heating behind the rupture front. Changing through our simulations, source geometries, and fault zone properties, we demonstrate that the process-zone dissipation due to the damage-breakage mechanism, and the isotropic source component, significantly affect the radiation pattern, rupture directivity, S/P energy partitioning, seismic potency and moment, and more. The results are significant for understanding better the proper usage and limitations of methods applied within the observational framework of earthquake seismology.
The effect of seismic-like induced cyclic loading on damage response of sandstone and granite
Authors: Geranmayeh Vaneghi Rashid , V. Dyskin Arcady , Thoeni Klaus , Sharifzadeh Mostafa , Sarmadivaleh Mohammad
Published: March 2020

The detailed study of rock response to cyclic loading induced by natural phenomena, such as seismic and volcanic activities, and man-made explosions and excavation is necessary for failure prediction and hazard mitigation. The effect of the maximum stress level, loading amplitude, and frequency of stress cycles on the fatigue life and failure mechanisms of two microstructurally different rocks of granite/granodiorite and sandstone is investigated. Test data obtained from comprehensive experiments conducted on these rock types incorporated with the results of previous studies show that the fatigue life time of both rock types increases with a decrease in either maximum stress level or stress amplitude. Nevertheless, the fatigue strength threshold of hard rocks like granite is generally lower than that of soft rocks like sandstone. The study also shows that the low-frequency cyclic loading has more damaging effect on both rock types than the high frequency loading. This investigation demonstrates that the failure mechanism of rocks under cyclic loading is characterized by the development of more tensile microcracks compared to the monotonic loading and the opening and extension of the axial tensile microfractures are more evident at higher maximum stresses or loading amplitudes or at lower loading frequencies. The results presented in this study will contribute to a deeper understanding of the fatigue responses of sandstone and granite to seismic-generated loading–unloading processes under different conditions of stress cycles.
A Late Pleistocene wetland setting in the hyperarid Jurf ed Darawish region in central Jordan
Authors: Mischke Steffen , Lai Zhongping , Faershtein Galina , Porat Naomi , Braun Paul , Kalbe Johannes , Ginat Hanan
Published: March 2020

Current conditions in the southern Levant are hyperarid and local communities rely on fossil subsurface water resources. However, the Levantine Corridor provided a pathway for the migration of humans out of Africa and their spread in the Near East and beyond in the Pleistocene, but times of more favourable wetter periods are not well constrained yet. To improve our understanding of past climate and environmental conditions in the deserts of the Near East, two nearby sedimentary sections (9.8 and 16.5 m thick, respectively) from the Central Jordanian Plateau containing a layer of stone tools and production debris were investigated using micropalaeontological analysis and OSL dating. Recorded fossils are mostly ostracod valves of the genera Pseudocandona, Potamocypris and Ilyocypris. Additional remains are shells of aquatic and terrestrial gastropods and charophyte gyrogonites and stem encrustations. The organism remains and mostly silty sediments suggest that a wetland with small streams and ponds existed at the location of Jurf ed Darawish in the past. OSL dating of the sedimentary sequence revealed mostly Late Pleistocene ages of the Marine Isotope Stages 4 and 3. The sedimentary layer containing stone tools and production debris was formed ca. 60 ka ago. In contrast, the base of the section provided only minimum ages of ca. 150 ka. The accumulated data indicate that climate conditions supported human activities on the Central Jordanian Plateau in the middle part of the Late Pleistocene.
Nearshore morphodynamics along the coastline of southern Sweden from detailed surficial mapping and hydrodynamic modelling
Authors: Nyberg Johan , Goodfellow Bradley , Ising Jonas , Hedenström Anna
Published: March 2020

With a view to assessing morphodynamic responses of the southern Swedish coast to predicted future sea level rise, the Geological Survey of Sweden has conducted detailed onshore and offshore sediment mapping and commissioned modelling of nearshore wave and current dynamics. Seamless, full coverage land and seabed mapping from approximately 3 m above sea level to 1000 m offshore has been completed along 500 km of coastline. On land, mapping of surficial sediments was done using conventional field-based methods and a high-resolution LIDAR-based digital elevation model. For the seabed, sediment and bathymetric mapping was based on ship-borne hydroacoustic surveying data, as shallow and close to shore as permitted by the ship draught, involving multibeam, swath-sonar, side-scanning sonar, sediment profiling and reflection seismics. For the white ribbon zone, i.e., the nearshore zone that is too shallow for the ships to enter, airplane-borne LIDAR and orthophoto-data were acquired. Ground-truthing in the form of sediment-sampling and visual observations was also done to verify sediment interpretations in the hydro-acoustical data. The exposure of the coast to waves and currents was modelled from several decades of historical wind data.  The sediment-, bathymetric- and topographic data were then combined with the modelled data of exposure to wind, waves, and currents to analyze spatial patterns of sediment erosion, transport and deposition. The results have been compiled into maps showing the location and distribution of mobile sediments, their transport pathways and storage compartments in the nearshore and deeper offshore zones, whether these compartments are closed or leaky, and their onshore-offshore exchange, including long-term trends in coastline accretion and erosion. The results show the coastline adapting to sea level rise that is associated both with the cessation of postglacial isostatic uplift and global warming, and to other climatic factors such as long-term changes in dominant wind direction.  At present, erosion causing long-term shoreline recession is localized. However, there is high potential for this to become a much more general and high magnitude problem in coming decades along this heavily populated, low lying, sedimentary coastline.
Variations of upper atmospheric high-order solar tidal harmonics during sudden stratospheric warming 2018
Authors: He Maosheng , Forbes Jeffrey , Chau Jorge , Li Guozhu , Wan Weixing , Korotyshkin Dmitry
Published: March 2020

Solar tides are the most predictably-occurring waves in the upper atmosphere. Although the dynamical theory can be dated back to Laplace in the 16th century, in the upper atmosphere tides  were rarely studied observationally until satellites and ground-based radars became common. To date, studies have mainly focused on low-order harmonics. Here, we combine mesospheric wind observations from three longitudinal sectors to investigate high-order harmonics. Results illustrate that the first six harmonics appear in early 2018, all of which are dominated by sum-synchronous components. Among these harmonics, the 6hr, 4.8hr, and 4hr components weaken at the sudden stratospheric warming (SSW) onset. The weakening could be explained in terms of variations in the background zonal wind.
Fault (un-)stability and strain partitioning across the brittle-ductile transition
Authors: Aubry Jérôme , Passelègue François , Escartín Javier , Deldicque Damien , Gasc Julien , Marty Samson , Page Marine , Schubnel Alexandre
Published: March 2020

In the lithosphere, the transition from brittle to ductile deformation corresponds to a regime where brittle fracturing and plastic flow coexist, called the semi-brittle deformation zone. Within these different regimes, a large fault slip spectrum has been observed, from fast to slow earthquakes. Studying the parameters controlling fault (un-)stability and strain partitioning across this transition is fundamental to understand how natural faults behave at varying crustal depths.

To investigate semi-brittle deformation and the conditions promoting it, we report here the results of experiments performed on Carrara marble saw-cut faults in triaxial conditions. We studied the influence of the confining pressure, axial loading rates and initial fault roughness on fault (un-)stability. From mechanical data, we performed strain partitioning calculations to infer elastic, frictional and plastic strain contributions during the deformation process.

We conclude that (laboratory) earthquakes may nucleate within a regime where homogeneous plastic deformation of the bulk and dynamic fault slip may coexist. The contribution of plastic strain is promoted with increasing confining pressure and fault roughness.
Geoscience education in a Nepali school
Authors: pandey Kalpana
Published: March 2020

Nepal lies in the center of the Himalayas range and it is also in the active seismic zone. We have regularly experienced different kinds of geohazards like as earthquake, landslides, floods etc. Most of the students in Nepal badly felt the 2015 Gorkha earthquake but fortunately, it was during the weekend and schools were closed.

For the purpose of earthquake education, we have installed seismometer inside the school under the framework of Seismology at School in Nepal program, which is recording earthquake continuously. We are teaching earth science in the classrooms using the seismometer. This seismometer is very good for the education purposes as each element is visible and easy to install in the classroom. In addition, we teach about seismic risk in the special lectures in classes range between 5 -12 using different educational materials provided by the Seismology at School in Nepal program. Sometimes, extra activities including the members from the communities are also performed to share the knowledge about natural hazards, its associated risk and the preparedness. The level of awareness and the motivation towards geoscience is found to be increased in the community after the installation of the seismometer. Students are interested to know the fact and real science even it is not the part of the official curriculum. It would be great if geoscience education in inserted to the high school curriculum. From the side of school, we are looking for the support and more materials to teach geoscience in the classroom in the future.
Carbon dioxide retrieval from OCO-2 satellite observations using the nonlinear least squares four-dimensional variational method: observing system simulation experiments
Authors: Jin Zhe , Tian Xiangjun
Published: March 2020

In this study, we apply the nonlinear least squares four-dimensional variational (NLS-4DVar) method to the retrieval of the column-averaged dry air mole fraction of carbon dioxide (XCO2 ) from the Orbiting Carbon Observatory-2 (OCO-2) satellite observations. The NLS-4DVar method avoids the computation of the tangent linear and adjoint models of the forward model, which reduces the computational and implementation complexity greatly. We use the forward model from the Atmospheric CO2 Observations from Space (ACOS) XCO2 retrieval algorithm. The inverse model is constructed of two parts, generating samples and minimizing the cost function. For the CO2 profile, we apply an improved sampling algorithm based on ensemble singular value decomposition (SVD). For the other elements in the state vector, we apply a sampling algorithm based on normal distributions, and values of standard deviations of normal distributions are vital to the accuracy of retrieval. To minimize the cost function, the NLS-4Dvar method rewrite it into a nonlinear least squares problem, and solve it by a Gauss-Newton iterative method. We have tested our method in summer and winter at four sites through observing system simulation experiments, which are Lamont, Bremen, Wollongong and an ocean site in the North Pacific respectively. All the four sites show an improved XCO2 and CO2 profile after the retrieval.
Using stable isotopes to understand water flow paths and ages in complex urban catchments
Authors: Marx Christian , Soulsby Chris , Hinkelmann Reinhard , Tetzlaff Dörthe
Published: March 2020

The need to understand how urbanization impacts the hydrological cycle and creates a complex, hybrid system of artificial and natural flow paths is an increasing focus of research.  A key question is how routing processes are affected by preferential flow of urban runoff into storm drains and infiltration trenches, and how this affects catchment travel time distributions of water and groundwater recharge. Isotopic tracers are commonly used in hydrology in order to identify dominant runoff sources, track flows paths and estimate water ages. However, isotope studies in urban areas are surprisingly scarce.  Here, we address this research gap by using stable isotopes for a preliminary investigation of the effects of urbanization on the stream flow generation and groundwater  discharge in the Panke catchment (230 km²) in the northern part of Berlin. The Panke is highly urbanised, with the built areas occupying 30% of the catchment, and a waste water treatment plant (WWTP) for around 700,000 people. Daily isotope samples of precipitation and streamflow were collected through the transition period from summer (dry) to winter (wet) conditions. In addition, spatially synoptic surveys in summer and winter gathered samples from throughout the catchment surface water drainage network and numerous groundwater wells. The natural hydrology of the catchment is groundwater-dominated, with isotopes indicating that an aquifer of glacial sands and gravel still providing the main source of runoff in the catchment headwaters, upstream of Berlin. Increasingly downstream, urban impacts become more dominant, especially during high flows when urban storm drains are active. In addition, the isotopic imprint of discharge from a WWTP dominates baseflow composition in the lower catchment. This preliminary work will be extended throughout 2020 and ultimately seek to inform models to quantify how the travel time distributions of the catchment have changed due to urban drainage, and how both impermeable surfaces and urban green space affect the spatial distribution of groundwater recharge.

 
Attribution of inter-annual and seasonal hydrological alteration to climatic and anthropologic changes at a perennial basin in Southeast China
Authors: Zha Xini
Published: March 2020

Change detection and attribution of water cycle are increasingly crucial for promoting society‘s capacity to embed adaptation planning confronting both climate change and anthropogenic forces at catchment scale. Nevertheless, current researches either neglect the difference between internal climate variability and climate change (including internal climate variability and external radiative forcing) or don’t consider different anthropogenic activities (e.g. land use changes, reservoir operation and water consumption). In this study, a new stepwise multiply scenarios approach (SMSA), using model simulations of the Fifth Coupled Model Intercomparison Project (CMIP5) archive and the new generation Soil and Water Assessment Tool (SWAT), dubbed SWAT+ model to identify and quantify influence of total five different factors (internal climate variability, external radiative forcing, land use changes, reservoir operation and water consumption) on inter-annual and seasonal hydrological alteration. Application of this approach to a perennial basin in Southeast China highlights the role of reservoir operation. 
Application of on-site EEW technology in South Korea.
Authors: Lee Ho Jun , Seo Jeong Beom , Lee Jin Koo , Jeon Inchan
Published: March 2020

The potential seismic hazard in South Korea is known to be that mid-sized earthquakes could occur nationwide. Because the damages of mid-sized earthquake are concentrated only in the vicinity of the epicenter, on-site EEW technology is known to be effective as a means to reduce absence of alarm near the epicenter and to ensure safety from earthquake threat. This study aims to simulate on-site EEW suitable for South Korea's seismic observation environment and verify its reliability. Seismic observations of 267 events occurred in South Korea, have been collected over the past five years for the simulation . Filter Picker was utilized to detect P-wave features from more than 37,000 data sets using a time window suitable for mid-sized earthquakes. The ground noises are removed from the detected P-waves, and a linear empirical relationship between the maximum P-wave amplitudes in vertical direction and observed PGVs on the base rock are derived. Convert the forecasted and observed PGVs to MMI, respectively. Assuming a successful prediction within the MMI±1 margin of error by comparing the two values, the results of this study showed an 80% success rate in the range above MMI 4. Through this study, feasibility and performance of on-site EEWS using domestic earthquake records were verified in South Korea. It is expected that this will contribute to the reduction of earthquake damage near the epicenter through an on-site warning in Korea.
The Effects of Hyperbolic Meteoroids from Parker Solar Probe to the Moon
Authors: Szalay Jamey , Pokorny Petr , Horanyi Mihaly , Bale Stuart , Christian Eric , Goetz Keith , Goodrich Katherine , Hill Matthew , Kuchner Marc , Larsen Rhiannon , Malaspina David , McComas David , Mitchell Donald , Page Brent , Schwadron Nathan
Published: March 2020

The zodiacal cloud in the inner solar system undergoes continual evolution, as its dust grains are collisionally ground and sublimated into smaller and smaller sizes. Sufficiently small (~<500 nm) grains known as beta-meteoroids are ejected from the inner solar system on hyperbolic orbits under the influence of solar radiation pressure. These small grains can reach significantly larger speeds than those in the nominal zodiacal cloud and impact the surfaces of airless bodies. Since the discovery of the Moon's asymmetric ejecta cloud, the origin of its sunward-canted density enhancement has not been well understood. We propose impact ejecta from beta-meteoroids that hit the Moon's sunward side could explain this unresolved asymmetry. The proposed hypothesis rests on the fact that beta-meteoroids are one of the few truly asymmetric meteoroid sources in the solar system, as unbound grains always travel away from the Sun and lack a symmetric inbound counterpart. This finding suggests beta-meteoroids may also contribute to the evolution of other airless surfaces in the inner solar system as well as within other exo-zodiacal disks. We will also highlight recent observations from the Parker Solar Probe (PSP) spacecraft, which suggest it is being bombarded by the very same beta-meteoroids. We discuss how observations by PSP, which lacks a dedicated dust detector, can be used to inform the structure and variability of beta-meteoroids in the inner solar system closer to the Sun than ever before.
Space oddity: estimating Earth biodiversity from a satellite
Authors: Rocchini Duccio
Published: March 2020

Assessing biodiversity from field-based data is difficult for a number of practical reasons: (i) establishing the total number of sampling units to be investigated and the sampling design (e.g. systematic, random, stratified) can be difficult; (ii) the choice of the sampling design can affect the results; and (iii) defining the focal population of interest can be challenging. Satellite remote sensing is one of the most cost-effective and comprehensive approaches to identify biodiversity hotspots and predict changes in species composition. This is because, in contrast to field-based methods, it allows for complete spatial coverages of the Earth's surface under study over a short period of time. Furthermore, satellite remote sensing provides repeated measures, thus making it possible to study temporal changes in biodiversity. While taxonomic diversity measures have long been established, problems arising from abundance related measures have not been yet disentangled. Moreover, little has been done to account for functional diversity besides taxonomic diversity measures. The aim of this talk is to propose robust measures of remotely sensed heterogeneity to perform exploratory analysis for the detection of hotspots of taxonomic and functional diversity of plant species.
The Nature of Intrinsic Attenuation
Authors: Wu Yu-Chang , Wu Cheng-Ju
Published: March 2020

Intrinsic attenuation plays an important role in investigating the interior structure of Earth, especially for the Lithosphere-asthenosphere system, the best place to understand the physical mechanics of plate tectonic. The dissipation, the high attenuation of seismic waves in the low-velocity zones, and the frequency dependence are the characteristic of intrinsic attenuation. However, N. Takeuchi, et al. measured the Northwestern Pacific Ocean’s lithosphere-asthenosphere system, and state the attenuation of the asthenosphere is 50 times larger than the attenuation of lithosphere attenuation. The attenuation of the lithosphere shows strong frequency dependency, but the attenuation of the asthenosphere does not. Previous theories of attenuation failed to explain this phenomenon. Here we demonstrate an explicit attenuation formulation to explain the high attenuation of seismic waves in the low-velocity zones and to show the mechanisms of spectral of teleseismic body waves rapidly fall off as frequency bigger than 1 Hz by perturbing the wave equation with the novel method we proposed. The result also indicates that the difference between the attenuation of the lithosphere and asthenosphere is because their attenuation governs by different physics mechanisms and mathematical models. Moreover, we illustrate the explicit formulation of the relationship between apparent t*, wave velocity, and frequency.
Multi-scale global reconstruction of water fluxes and states with mHM
Authors: Samaniego Luis , Kaluza Maren , Thober Stephen , Rakovec Oldrich
Published: March 2020

Land surface and hydrologic models (LSM/HMs) have been typically calibrated with streamflow for selected river basins. This procedure, although it is the current standard, it is highly disadvantageous because the resulting model 1) is not transferable to other locations and scales, 2) it underperforms against multivariate data not used during calibration, and 3) simulated fluxes do not fulfill the flux-matching closure condition [1] if compared across scales. These shortcomings lead to parameter fields exhibiting artifacts and sharp discontinuities over space (not seamless) [2] and thus, to a poor spatial representation of water fluxes and states. Existing terrestrial water cycle observations have spatial supports ranging from few hundred square meters to hundred square kilometers. Currently, most of the existing LSM/HMs are not able to assimilate simultaneously these observations because they do not have scale-invariant parameterizations. Preliminary tests at continental scale indicate that nested multiscale simulations are possible only if the model exhibits a scale-invariant parameterization [3]. In mHM [4], this capability is provided via the multiscale parameter regionalization (MPR) technique [1].

In this study, transfer-function parameters for mHM are estimated with 5500 GRDC streamflow time series, tens of FLUXNET evapotranspiration products, and the terrestrial total water storage anomaly (GRACE). This parameter estimation problem at global-scale requires a powerful supercomputer (JUWELS) [5] and the usage of recently implemented and extremely efficient parallelized algorithms [6]. The daily reconstructed high-resolution hydrologic simulations (0.25°) since 1950 reveal that the use of the MPR technique improves the overall model efficiency (compared to other global models [7]) and allows us to identify locations of consistent changes in hydrologic variables responding to long-term climate variability. The median of the NSE for the uncalibrated mHM model over the selected GRDC stations reaches a value of 0.40 for daily streamflow. Models reported in Beck et al. [7] exhibit a mean value of -0.09! This indicates the great potential of the proposed method. Comparison of terrestrial water storage (TWS) of GRACE against mHM simulations reveals hotspots of weaker model performance in regions where the water balance closure error is large. 

References

[1] https://doi.org/10.1029/2008WR007327
[2] https://doi.org/10.5194/hess-21-4323-2017
[3] https://doi.org/10.1175/JHM-D-15-0054.1
[4] www.ufz.de/mhm
[5] http://www.fz-juelich.de/ias/jsc/juwels
[6] https://meetingorganizer.copernicus.org/EGU2019/EGU2019-8129-1.pdf
[7] https://doi.org/10.1002/2015WR018247
Influence of pore geometry on motility and trapping of metal reducing bacteria
Authors: Perez Lazaro J. , Sund Nicole L. , Parashar Rishi , Plymale Andrew E. , Hu Dehong , Scheibe Timothy D.
Published: March 2020

Diverse processes such as bioremediation, biofertilization, and microbial drug delivery
rely on bacterial migration in porous media. However, how pore-scale confinement alters
bacterial motility is unknown due to the inherent heterogeneity in porous media. As a
result, models of migration are limited and often employ ad hoc assumptions.
We aim to determine the impact of pore confinement in the spreading dynamics of two
populations of motile metal reducing bacteria by directly visualizing individual Acidovorax
and Pelosinus in an unconfined liquid medium and in a microfluidic chip containing regular
placed pillars. We observe that the length of runs of the two species differs from the
unconfined and confined medium. Results show that bacteria in the confined medium
display a systematic shorter jumps due to grain obstacles when compared to the open
porous medium. Close inspection of the trajectories reveals that cells are intermittently
and transiently trapped, which produces superdiffusive motion at early and subdiffusion
behavior at late times, as they navigate through the confined pore space. While in the open
medium, we observe a linearly increasing variance with respect to time for Acidovorax, and
for Pelosinus the variance increases at a much faster rate showing super diffusive behavior
at early times. At late times, the rate of growth in spreading increases for Acidovorax while
it reduces for Pelosinus. We finally discuss that the paradigm of run-and-tumble motility
is dramatically altered in the confined porous medium and its practical applications of
these effects on large-scale transport.
Glacial Termination: Going, Going, Gone
Authors: Knorr Gregor , Barker Stephen
Published: March 2020

Within the Late Pleistocene, a ‘termination’ is the name given to the rapid (~10kyr) deglacial transition marking the end of a (~100kyr) glacial cycle. These massive events involve all the critical elements of Earth’s climate system: global temperatures, precipitation patterns, ice sheet extent, ocean and atmospheric circulation systems, atmospheric composition and biological activity. Investigations into the mechanisms of glacial termination have been many and it is now thought that abrupt shifts in the ocean/atmosphere system play a ubiquitous and critical role in deglaciation. However, significant uncertainties remain concerning the timing and magnitude of deglacial changes and the likelihood that they will be interrupted by ‘terminal oscillations’ such as the Bølling-Allerød / Younger Dryas oscillation during Termination 1. In this presentation we will address these uncertainties in the light of recent developments in the understanding of glacial terminations as the ultimate expression of the interaction between millennial and orbital timescale variations in Earth’s climate. Innovations in numerical climate simulation and new geologic records that enable us to test these simulations allow us to highlight new avenues of research as well as to emphasise the importance of lingering uncertainties in key climatic parameters such as sea level variability through time.
Determination of the Ni isotope fractionation in microfossils embedded in the aragonite phase
Authors: Tulej Marek , Neubeck Anna , Lukmanov Rustam , Grimaudo Valentine , Riedo Andreas , Cedeño López Alena , de Koning Coenraad, Pieter , Ligterink Niels, Frank, Willem , Ivarsson Magnus , Wurz Peter
Published: March 2020

Stable nickel isotopes are known to fractionate by biological processes and their measurements can be important biomarker. In searches for ancient fossilised materials such as microbial cells, the Ni isotope fractionation record can be preserved after death and fossilization of microstructures. Typically, transition metal isotopes in microfossils are difficult to measure accurately because of their low concentration in the fossil. Furthermore, microsized fossil structures  are difficult to isolate from the host phase. Thus, the measurement of their chemical composition can be conducted only by a few  analytical methods. We have applied femtosecond-laser ablation/ionisation time-of-flight mass spectrometry (LIMS) to measure chemical composition of the fossilised material embedded in the aragonite phase and accurately derive the Ni isotopic fractionation pattern. High resolution depth profiling method was applied to isolate fossilised material composition from the host phase. The mass peak intensity correlation and peak integration methods were subsequently applied to derive isotope concentrations. The accuracies and precision in permill level or better of the isotope values were achieved. For comparison the studies of Ni isotopes were conducted on inorganic samples. The instrument used in the studies is a miniature mass analyser developed for space research holding promisses that differentiation between abiotic and biogenic microstructures in rocks can be studied also in situ on the surfaces of Solar System bodies.

References

1. U. Rohner et al., Meas. Sci. Technol. 14 (2003) 2159–2164

2. A. Riedo et al., JAAS, 28:1256–1269, 2013

3. A. Neubeck et al., Int. J. Astrobiology, 15, 133-146, 2016

4. M. Tulej et al., Astrobiology, 2015, DOI: 10.1089/ast.2015.1304;JAAS,33(8):1292-1303, 2018

5. S. Meyer et al., J. Mass Spectrom. 2017, DOI: org/10.1002/jms.3964   

6. R. Wisendanger et al., J. Chemometrics, 2018, DOI: 10.1002/cem.3081

7. V. Grimaudo et al., Anal. Chem., 2018, DOI: 10.1021/acs.analchem.7b05313

 

 
Hydraulic and sediment transport metrics of river systems from inverse modelling of seismic ground motion data
Authors: Dietze Michael , Lagarde Sophie , Halfi Eran , Polvi Lina E. , Lotsari Eliisa , Turowski Jens M. , Laronne Jonathan B. , Hovius Niels
Published: March 2020

Constraining bedload flux in rivers is a challenging objective, especially when the data need to be continuous, beyond-point estimates. Seismometers are potentially valuable alternatives to in‐stream devices, which involve extensive measurement infrastructure or labour‐intensive manual sampling that can be potentially dangerous. We present a Monte Carlo-based inverse approach to deducing hydraulic and bedload transport dynamics continuously, with high temporal resolution, from seismic data, that averages the system’s behaviour over tens of metres. Water depths and bedload fluxes can be reproduced with average deviations of 0.10 m and 0.02 kg/sm, respectively. The method is validated against synthetic data sets and independently measured metrics from several challenging streams: we show applications of the technique from a flash flood-dominated catchment in Israel (Nahal Eshtemoa), from an ice-covered subarctic river (Sävarån, Sweden), and from a typhoon-driven major mountain river in Taiwan (Liwu River). The presented approach is a generic method implemented in the R package ‘eseis’ that can be used with off-the-shelf seismic equipment, installed at safe distances from potentially hostile conditions with minimum site disturbance.
Seismic attribute mapping of a fluvial reservoir in Rhourde Chegga field (Hassi Messaoud, Algeria)
Authors: Medjdouba Nasrine , benaissa zahia , boudella amar
Published: March 2020

Rhourde Chegga field is located in the north of Hassi Messaoud giant field, Algeria. The main hydrocarbon-bearing reservoir in Rhourde Chegga field is the lower Triassic Argilo-Gréseux reservoir. The Triassic sand is deposited as fluvial channels and overbank sands with a thickness ranging from 15 to 20 m, lying unconformably on the Paleozoic formations. Lateral and vertical distribution of the sand bodies makes their mapping very difficult and, sometimes, even impossible with conventional seismic interpretation. 

To better define drilling targets within the Triassic sand in the Rhourde Chegga field, 3D stratigraphic seismic attribute analysis was performed along the reservoir level, using PSTM and mid angle stack seismic data. By combining various attributes (RMS amplitude, half energy, variance, etc.), the channelized feature has been clearly imaged and delineated on the horizon slices and the volume extraction. The relationship between the combined seismic attributes and reservoir properties at well locations showed a good correlation.

Based on this study, about ten produced wells have been successfully drilled, confirming the efficiency of seismic attribute analysis to predicted channel body geometry.

Keywords: Channel, Attributes, Amplitude, Fluvial reservoir.

 
Modelling regional- and global-scale glacier volume changes over the last millennium
Authors: Parkes David , Goosse Hugues
Published: March 2020

We demonstrate modelling of regional- and global-scale volume changes in glaciers over the last millennium with the Open Global Glacier Model (OGGM) - a glacier geometry and surface mass balance model in active development - using reconstructed climate data timeseries from a set of 6 GCMs. The goals are: 1) to better understand how well different longer-term (extending back to the pre-industrial period) climate datasets perform specifically in terms of their impact on glaciers; 2) to analyse the ability of OGGM to model glaciers over longer timescales while still capturing observed changes over the period of instrumental record; and 3) to determine which regions are better or worse suited to this type of modelling on large scales. A secondary goal is to understand the relative impact of precipitation and temperature - the two primary climate variables used to drive OGGM - on regional glacier volume over this time period, using synthetic climate inputs which isolate long-term trends from each variable individually. Modelling over this last millennium timescale is important due to the preponderance of available instrumental data being much more recent, with glacier models developed and calibrated using data that are mostly recorded in a period of pronounced global glacier retreat. Modelling periods that include both recent warming (and associated observed glacier retreat) and the preceding period that is without such globally coherent changes in climate provides a valuable test of glacier models, to ensure they can generate both relative stability in glacier geometry in stable climates with realistic variability and subsequent reduction in ice mass where appropriate in response to clearer recent temperature trends.
Plant‐mycorrhizae association affects plant diversity, biomass, and soil nutrients along temporal gradients of natural restoration after farmland abandonment in the Loess Plateau, China
Authors: Liu Hongfei , Xue Sha , Liu Guobin
Published: March 2020

The interaction between plants and arbuscular mycorrhizal fungi in the rhizosphere plays a vital role in driving vegetation recovery and restoration of soil nutrients. However, how this interaction affects vegetation succession and how soil nutrient recovery is driven by vegetation restoration and rhizosphere processes are still largely unknown. In this study, a well‐documented grassland restoration chronosequence on the Loess Plateau, China (fields at 0, 7, 12, 17, 22, and 32 years after farmland abandonment and a natural grassland reference) was selected. The species richness and diversity reached maximum values between 17 and 22 years after farmland abandonment, whereas the plant total above and belowground biomasses simultaneously peaked at 22 years and then remained stable. In the dominant plant rhizosphere and bulk soil concentrations of total glomalin‐related soil protein (including both old and recently produced fungal proteins) substantially increased from 3.58 to 4.87 g kg-1 and from 2.67 to 3.86 g kg-1, respectively, between 12 and 32 years after farmland abandonment. The concentrations of soil organic carbon (SOC) and total nitrogen (TN) in the plant rhizosphere and bulk soil significantly increased between 17 and 32 years and reached the levels of the natural grassland. The aboveground plant biomass, soil SOC, and TN concentrations were positively correlated with the glomalin‐related soil protein (GRSP) concentration (p < 0.05). Our study suggested that interactions among plant‐mycorrhizae association, plant diversity, and biomass promote GRSP and nutrient accumulation in the plant rhizosphere and bulk soil, and GRSP largely contributes to SOC stabilization and the accumulation of SOC and TN.
Design and implementation of climate and flood risks educational program in Mali, West Africa: A methodological approach
Authors: Sambou Djiby
Published: March 2020

The republic of Mali, like other countries in the Sahelian zone, is highly vulnerable to climate and flood risks. Also, in recent years, Mali has engaged in prevention, mitigation and adaptation to climate change effects, by adopting different policies and strategies. The design and implementation of an educational program on climate change and floods are part of strategies to strengthen resilience of populations. The objective of this program is to develop climate and flood risk culture, to explain and make children, from 6 to 15 years, understand actions to prevent, protect and adapt in extreme climate and flood events. It will be integrated into school curricula. The methodological approach adopted is based on two major principles:  involvement of all potential actors in the process and adaptation of the program to the cultural context of the country; in order to guarantee national ownership, sustainability of activities and success. These steps and activities have been used to define and implement the program: 1) analyze the situation in Mali in terms of climate change and flood risk; 2 identify stakeholders that are involved in curricula development; 3) define the skills benchmark; 4) design the program; 5) share the program that has been developed with all stakeholders and teachers; 6) test and evaluate the program in schools; 7) generalize and perpetuate the program in Malian educational system.
Characterization of the St. Lawrence Estuary's suspended matter size and composition
Authors: Fabris Anne-Sophie , Larouche Pierre , Montero-Serrano Jean-Carlos
Published: March 2020

The St. Lawrence Estuary is a large seasonally ice-covered estuarine system in eastern Canada. The suspended particulate matter (SPM) dynamic in this estuary is strongly influenced by winds, tides, river runoff, and coastal jets. The particle size distribution (PSD) is an important property of the SPM as it may affect sinking rates, particle re-suspension and distribution of pollutants. A deeper understanding of the PSD helps to determine the vertical and horizontal fluxes of the matter in the water column.

Although information exists concerning the composition and the SPM dynamic in the St. Lawrence Estuary in summer, there is a lack of recent spatial and vertical characterization while no winter data is available. Thus, the purpose of this study is to better characterize the SPM particle size and sedimentological properties in the St. Lawrence Estuary during summer and winter conditions.

The PSD was measured using a laser diffractometer LISST-100X directly in the water column during the summer of 2010 and in the laboratory using water samples taken at discrete depths for winter 2019. X-ray diffraction and fluorescence analysis were used for the characterization of the particles’ mineralogical and chemical composition from which the detrital sources were evaluated.

Results show that SPM concentration is spatially more variable during summer than in winter. In contrast, the PSD’s is inverted in winter with relatively smaller size particles upstream and larger particles downstream. The depth distribution of the PSD shows slight differences between the seasons. In summer, larger particles are mostly present at the pycnocline whereas in winter, larger particles reach deeper depths and are mostly of inorganic origin. Throughout the estuary for both seasons, particulate inorganic matter contributed the most to total SPM. The winter mineralogical and chemical composition of the SPM was similar throughout the estuary confirming previous studies indicating an origin from the Canadian Shield. Taken as a whole, this study provided valuable new information on suspended matter dynamics in a large Subarctic estuarine environment.
Estimation of evapotranspiration components across China based on a modified Priestley–Taylor algorithm with assimilated soil moisture data
Authors: Xing Wanqiu , Wang Weiguang , Deng Chao , Chen Zefeng
Published: March 2020

Consisting of evaporation from wet surfaces (E) and transpiration through plants (T), evapotranspiration (ET) is an integral part of earth’s ecological and climate systems. Since the different ET components have their certain water resource function and ecological significance, accurate estimation of regional ET components is essential to better understand water cycle and surface energy budget. Incorporating soil relative humidity (SRH) into remote sensing ET algorithm, this study presented an update to the widely-used Priestley Taylor-Jet Propulsion Laboratory (PT-JPL) ET algorithm to incorporate spatially explicit monthly SRH control on soil evaporation (Es) and canopy transpiration (T). The updated algorithm (i.e., PT-SM) was evaluated using 17 eddy covariance towers across different biomes, and 24 hydrological catchments across different climatic regions of China, respectively. The PT-SM model shows increased R2 and NSE, and reduced RMSE and Bias, with the greatest improvements occurring in water-limited regions. SRH incorporation into Es can improve ET estimates by increasing R2 and NSE by 3% and 17%, respectively, and RMSE and Bias were reduced by 13% and 26%, respectively, while SRH incorporation into T would improve ET estimates by raising R2 and NSE by 6% and 27%, respectively, and RMSE and Bias were reduced by 32% and 63%, respectively. We apply the algorithm to the whole China using SRH data at depths [10-cm, 20-cm, and 50-cm] and a resolution of 0.5° × 0.5° assimilated by the farmland soil moisture observation, the NASA’s Gravity Recovery And Climate Experiment (GRACE) solutions and observed precipitation. The mean annual of total estimated ET increased from the northwest to the southeast, with Es/ET and T/ET roughly presenting opposite spatial distribution characteristics.