bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating basal thaw as a driver of mass loss from the Antarctic ice sheet
Authors: Dawson Eliza , Schroeder Dustin , Chu Winni , Mantelli Elisa , Seroussi Hélène
Published: March 2022

Contemporary mass loss from the Antarctic ice sheet primarily originates from the discharge of
marine-terminating glaciers and ice streams. The rate of mass loss is influenced by warming ocean
and atmospheric conditions, which lead to subsequent thinning or disintegration of ice shelves and
increased outflow of upstream grounded ice. It is currently unclear how the basal thermal state of
grounded ice could evolve in the future - for example as a result of accelerated ice flow or changes
in the ice sheet geometry - but a change in the basal thermal state could impact rates of mass loss
from Antarctica. Here, we use a combination of numerical simulations and ice-penetrating radar
analysis to investigate the influence of basal thawing on 100yr simulations of the Antarctic ice
sheet’s evolution. Using the Ice-sheet and Sea-level System Model, we find that thawing patches
of frozen bed near the ice sheet margin could drive mass loss extending into the continental
interior, with the highest rates of loss coming from the George V - Adélie - Wilkes Land coast and
the Enderby - Kemp Land regions of East Antarctica. This suggests that the thawing of localized
frozen bed patches is sufficient to cause these East Antarctic regions to transition to an unstable
mass loss regime. We constrain model estimates of the basal thermal state using ice-penetrating
radar surveys and analyze radar characteristics including bed reflectivity and attenuation. In
combination, our work identifies critical regions of Antarctica where the ice-bed interface could
be close to thawing and where basal thaw could most impact mass loss.
Two-stage rifting of Jiaolai Basin, Eastern China, decoding from the source-to-sink reconstruction
Authors: Zhang Bo , Liu Shaofeng , Lin Chengfa , Ma Pengfei
Published: March 2022

The basin is an essential window for exploring tectonic evolution, which preserves the information of regional extension, subsidence, uplift, and denudation. The Jiaolai Basin, located on the northern the Sulu Orogenic Belt, records the extension events of East Asia and the post-orogenic evolution of the Sulu Orogenic Belt during the Cretaceous. Multiple provenance analyses were used in the study to reconstruct the source-to-sink system of the Laiyang Group in the Jiaolai Basin. The results show that the Jiaolai Basin has a two-stage evolution history. In the early Early Cretaceous (ca. 135-122Ma), the Zhucheng sag and Gaomi sag in the south developed firstly. Subsequently, in the late Early Cretaceous (ca. 121-113Ma), the Laiyang Sag in the north developed. Moreover, these sags undergone independent, multi-stage source-sink system evolution in their early stages, and shared similar provenance supply systems at the end of Laiyang Group (ca. 113Ma). The provenance analysis results show that at ~121 Ma, ultra-high pressure (UHP) rock undergone a rapid exhumation in the northern section of the Sulu orogenic belt, whereas, for the southern section, The UHP may not be exposed until ca.113Ma. The two-stage extension in Eastern Asia with the change in direction and magnitude, recorded in the Jiaolai basin, suggests the trench retreat and subduction direction Change of the Izanagi plate should be the first-order drive force of the extension events of Eastern Asia during the Cretaceous. Our results indicate that the change of the Izanagi subduction direction may be ~121 Ma.
Application of ground penetrating radar (GPR) in look-ahead detection of slurry balance shield machine
Authors: Duan Weiwei , Xie Xiongyao , Yang Yong , Zeng Kun , Wu Huiming , Zeng Li , Li Kang
Published: March 2022

The shield machine has become the mainstream of subway tunnels construction because of its safety and efficiency. But with the continuous development of urban construction, the environment of subway tunnel construction is becoming more and more complex. In the process of shield tunnels construction in southern cities of China, slurry balance shield machines often encounter various obstacles, such as large diameter boulders and concrete pile foundations, which result in accidents of shield machine sticking. Therefore, it is necessary to quickly and accurately detect the distribution of obstacles in front of shield excavation face in advance so that operators can in time take measures to reduce the occurrence of such accidents. Ground penetrating radar (GPR) is a method widely used in engineering geological exploration. It has advantages of small working space, high efficiency and no damage compared with other detecting methods. When the GPR antenna is mounted on the cutter head of the shield machine, the obstacles in the stratum ahead of the shield machine can be detected in real time. Under this condition the GPR antenna’s real work mode is that it will rotate with the cutter head to form a circumferential survey line. Based on Finite-Difference-Time-Domain-Method (FDTD), authors use the common numerical simulation software (GPRMAX) to make simulations of GPR circumferential detection under the antenna array rotating with the cutter head, which verifies the theoretical feasibility of this method. By simulating radar emission and reflection pattern of electromagnetic wave, we study the propagation pattern of the reflect wave after encountering the obstacles and conclude the image pattern to establish the foundation for image recognition of obstacles. Due to the radar wave being susceptible to electromagnetic interference, GPR is still lack of engineering practice in shield advanced detection. To reduce the interference of the surrounding metal cutter head, a new strip radar antenna with a shielding shutter is designed to improve the directivity of electromagnetic wave propagation. Several antennas are fixed at several slurry openings of the cutter head of slurry balance shield machine to form radar antenna array and improve detection efficiency and accuracy.
Representation of Low-Level Clouds in West Central Africa in a convection-permitting regional climate simulation
Authors: Champagne Olivier , Moron Vincent , Philippon Nathalie , Klein Cornelia
Published: March 2022

The region of Western Central Africa (WCA) is covered by a large deck of stratocumulus or stratus during the long dry season (June-September). These low clouds are an important component to sustain the Gabonese and Congolese forests, but they are not properly simulated by global climate models. The Pan-African convection-permitting decadal regional climate simulation (4 km resolution), conducted with the Met-office unified model (CP4-Africa), has so far facilitated great advances in scientific understanding on characteristics of organised deep-convection in the climate change context. However, it remains unclear whether there may also be added value in the simulation of extensive low-level clouds. Here, we concentrate on the CP4 historical period (1997-2006) and evaluate its representation of low clouds in WCA. We will present preliminary results on the ability of CP4 to simulate the diurnal and seasonal evolution of low clouds in WCA compared to in-situ observations, ERA5 reanalyses and the non-convection-permitting regional simulation (R25). R25 was run with a similar setup and global driving data as CP4, but using a convective parametrization, thus allowing direct attribution of simulation differences to resolution and the representation of convection. This work is relevant for our understanding of the processes responsible for the development and persistence of low clouds in WCA. Our results may also be used to assess whether future projections at km-scale such as from CP4 can provide more plausible depictions of low cloud changes.
Langmuir Probe observations during eclipses of Cassini with Saturn and the Main Rings: ring optical depths and photoelectrons
Authors: Xystouris Georgios , Arridge Christopher Stephen , Morooka Michiko , Wahlund Jan-Erik
Published: March 2022

The Langmuir Probe (LP) onboard Cassini was one of the three experiments that could measure the cold inner magnetospheric plasma, along with the Radio and Plasma Waves Science (RPWS) and the Cassini Plasma Spectrometer (CAPS). While the century-old LP theory looks quite straight-forward, in reality things are much more complicated.

The operation of the LP is quite simple: by applying positive bias voltages, the probe attracts the electrons and repels the ions of the surrounding plasma. From the resulting current-voltage curve characteristics of the ambient electrons can be estimated, i.e. density and temperature. When negative bias voltages are applied to the probe the characteristics of the ambient ions can be estimated, i.e. density, temperature, and mass.

Though the LP operation and interpretation are quite simple and straightforward, there are assumptions made and therefore the theoretical models may not always reflect the actual plasma conditions in Saturn’s magnetosphere. For this study we are focused on the effect of the photoelectrons, i.e. electrons generated by the incident sunlight on Cassini’s surfaces, that are difficult to calibrate for on the ground and then observe and characterise in the LP data.

We present algorithms for identifying when Cassini is in the shadow of Saturn and its rings, and when the LP is in the shadow of Saturn, its rings or Cassini itself. The LP data inside and outside the eclipses are compared using the algorithms developed. In this presentation we will first discuss the impact of the photoelectron generation from the spacecraft surfaces to the LP current-voltage curves, and understand the variations of the measured plasma density connected with the photoelectrons. Then, using that knowledge, we attempt to define the optical depth of the rings in the wavelengths the LP operates in.
Long-term ecosystem and biogeochemical research at the LTER site“Istituto Scientifico Angelo Mosso” (NW Italian Alps)
Authors: Freppaz Michele , Pintaldi Emanuele , Colombo Nicola , D'Amico Michele , Martin Maria , Lombardi Giampiero , Lonati Michele , Giardino Marco , Perotti Luigi , Balestrini Raffaella , Salerno Franco
Published: March 2022

The vast majority of studies in the ecological literature last less than three years, and only a small number of research works capture unusual events. To detect changes in high-mountain ecosystems, long-term research is mandatory, as these areas are important bellwethers of climate change. The LTER macrosite “Northwestern Italian Alps” includes the research site “Istituto Scientifico Angelo Mosso”, located in the alpine tundra close to the Monte Rosa Massif (NW Italy). The core of the LTER site is the Research Institute Angelo Mosso (2901 m a.s.l.), founded in 1907 by Angelo Mosso, professor of human physiology at the University of Turin. Over the years, the Institute has given support to scientists and scholars from all over the world, who could stay there even for long periods, while conducting their research activities in different research fields. At present times, it includes permanent plots, where different variables are constantly monitored, such as snow cover duration, vegetation composition and phenology, soil temperature, soil water content, and C and N forms. Moreover, the chemical characteristics of rainwater and snowfall are measured, as well as the water chemistry in ponds, focusing for example on how the soil properties control several hydrochemical properties such as the C and N content in water, following the critical zone paradigm. Research is also being carried out in order to investigate the hydrochemical characteristics of ponds and streams fed by different cryospheric features such as rock glaciers, glaciers, and permafrost, with a focus on the main associated weathering processes. Other permanent plots have been established in order to carry out investigations on paleoclimate through the information that could be derived from soils, integrating the information obtained in the same study area by ice core drilling. There is evidence that the paleoclimate influenced the cycling of soil carbon through shifting biomes and by altering soil physicochemical properties. The current distribution of soil carbon stocks thus contains footprints of the paleoclimate at timescales ranging from centuries to millennia. New research lines, aimed at investigating the most recent environmental challenges, have been added to the previous ones. Investigations on sources and routes of atmospheric nitrogen species, on the scarcely known biodiversity hosted in the glacial meltwater, and on the microplastic content in snow are ongoing, thus further extending the range of environmental processes investigated at this high-elevation site.
Convective dissolution of Carbon Dioxide in two- and three-dimensional porous media: the impact of hydrodynamic dispersion
Authors: Méheust Yves , Dhar Jayabrata , Meunier Patrice , Nadal François
Published: March 2022

Convective dissolution is the process by which CO2 injected in geological formations dissolves into the aqueous phase and thus remains stored perennially by gravity. It can be modeled by buoyancy-coupled Darcy flow and solute transport. The transport equation should include a diffusive term accounting for hydrodynamic dispersion, wherein the effective diffusion coefficient is proportional to the local interstitial velocity. We investigate the impact of the hydrodynamic dispersion tensor on convective dissolution in two-dimensional (2D) and three-dimensional (3D) homogeneous porous media. Using a novel numerical model we systematically analyze, among other observables, the time evolution of the fingers’ structure, dissolution flux in the quasi-constant flux regime, and mean concentration of the dissolved CO2; we also determine the onset time of convection, ton. For a given Rayleigh number Ra, the efficiency of convective dissolution over long times is controlled by ton. For porous media with a dispersion anisotropy commonly found in the subsurface, ton increases as a function of the longitudinal dispersion’s strength (S), in agreement with previous experimental findings and in contrast to previous numerical findings, a discrepancy which we explain. More generally, for a given strength of transverse dispersion, longitudinal dispersion always slows down convective dissolution, while for a given strength of longitudinal dispersion, transverse dispersion always accelerates it. Furthermore, systematic comparison between 2D and 3D results shows that they are consistent on all accounts, except for a slight difference in ton and a significant impact of Ra on the dependence of the finger number density on S in 3D.
Stabilization and reuse of PFAS contaminated soil and treatment of leachate and groundwater by Surface Active Foam Fractionation (SAFF)
Authors: Hinrichsen Helena , Murphy Peter , Stewart Richard
Published: March 2022

The management of soils, leachate, and groundwater contaminated with per and polyfluorinated alkyl substances (PFAS) is a major challenge worldwide. Conventional remediation methods are not applicable due to the inherent chemical stability of PFAS substances. On the other hand, landfill disposal, which is common in Europe for other soil contaminants, presents its own challenge for PFAS contaminants, as the disposal of PFAS soil in a landfill creates a concentrated point source of water-soluble substances that poses a threat to human health and the environment.

This paper presents some of the recent progress made in stabilizing PFAS in soil using Rembind's proprietary stabilizer and Surface Active Foam Fractionation (SAFF) for treating PFAS contaminated water with air and electricity only.

The results of a pilot project and two large-scale projects are presented and discussed in terms of the sustainability of the approaches and the total cost per unit of soil/water treated.

 
A rapid, low-cost, high-resolution, map-based assessment of the January 15, 2022 tsunami impact on population and buildings in the Kingdom of Tonga
Authors: Thomas Bruce Enki Oscar , Roger Jean , Gunnell Yanni
Published: March 2022

The population and built infrastructure of the Kingdom of Tonga are highly exposed to ocean- and climate-related coastal hazards. The archipelago was impacted on January 15, 2022, by a destructive tsunami caused by the Hunga Tonga-Hunga Ha'apai submarine volcanic eruption. Weeks later, several islands were still cut off from the world, this situation was made worse by covid-19-related international lockdowns and no precise idea of the magnitude and pattern of destruction. Like in most Pacific islands, the Kingdom of Tonga lacks an accurate population and infrastructure database. The occurrence of events such as this in remote island communities highlights the need for (1) precisely knowing the distribution of residential and public buildings, (2) evaluating what proportion of those would be vulnerable to a tsunami depending on various run-up scenarios, (3) providing tools to the local authorities for elaborating efficient evacuation plans and securing essential services outside the hazard zones. Using a GIS-based dasymetric mapping method previously tested in New Caledonia for assessing, calibrating, and mapping population distribution at high resolution, we produce maps that combine population clusters, critical elevation contours, and the precise location of essential services (hospitals, airports, shopping centers, etc.), backed up by before–after imagery accessible online. Results show that 62% of the population on the main island of Tonga lives in well-defined clusters between sea level and the 15 m elevation contour, which is also the value of the maximum tsunami run-up reported on this occasion. The patterns of vulnerability thus obtained for each island in the archipelago, are further compared to the destruction patterns recorded after the earthquake-related 2009 tsunami in Tonga, thereby also allowing us to rank exposure and potential for cumulative damage as a function of tsunami cause and source-area. By relying on low-cost tools and incomplete datasets for rapid implementation in the context of natural disasters, this approach can assist in (1) guiding emergency rescue targets, and (2) elaborating future land-use planning priorities for disaster risk-reduction purposes. By involving an interactive mapping tool to be shared with the resident population, the approach aims to enhance disaster-preparedness and resilience. It works for all types of natural hazards and is easily transferable to other insular settings.
The 15 January 2022 Hunga eruption, Tonga – first petrographic and geochemical results
Authors: Cronin Shane , Brenna Marco , Kula Taaniela , Ukstins Ingrid , Adams David , Wu Jie , Paredes Marino Joa , Kilgour Geoff , Leonard Graham , White James , Barker Simon , Gravley Darren
Published: March 2022

The phreatoplinan eruption of the shallow submarine Hunga Volcano Tonga formed global air-pressure waves, regional tsunami and an up to 55 km-high eruption column. Despite its large explosive magnitude, the magma erupted were similar to past compositions, and comprised crystal poor (<8 wt% total; plag>cpx>opx) andesite with ~57-63 wt% silica glass. Low magnitude Surtseyan eruptions in 2009-2015 formed from small pockets of andesite that ascended slowly, resulting in high microphenocryst and microlite contents. Large eruptions, including events in ~AD200 and AD1100 and the 2022 event drew magma rapidly from a ~5-7 km deep mid-crustal reservoir. Rapid decompression and quenching (augmented by magma-water interaction) records the heterogeneity of the reservoir, with mingled glass textures and cryptic mixing of subtly different melts. The 2022 feldspar phenocrysts show more mafic melt inclusion compositions than host glass, clear uniform cores and thin rims evidencing ~1 month-long changes caused by decompression, rise and internal mingling of subtlety different melts. CPX phenocrysts show uniform cores a variety of more mafic and similar melt inclusions to the bulk glass, and thin overgrowth rims reflecting only decompression and mingling. Lithic fragments (<8wt%) include common hydrothermal minerals (sulphides, quartz etc). Without evidence of a mafic trigger, or crystalisation induced overpressures, this extremely violent eruption was triggered by top-down processes that led to rapid exhumation/decompression of magma and very efficient explosive magma-water interaction. This could include any, or all of: flank collapse; hydrothermal seal fracturing and ingress of water into the upper magma system and caldera collapse. Subsequent earthquakes suggest that the crustal magma system was rapidly recharged in the days following the eruption.
Understanding fragmentation mechanism(s) during the 15 January 2022 Hunga Volcano (Tonga) eruption through particle characteristics
Authors: Paredes-Mariño Joali , White James , Dürig Tobias , Baxter Rachel , Kula Taaniela , Cronin Shane , Ukstins Ingrid , Wu Jie , Adams David , Brenna Marco , Brooks-Clarke Isabelle
Published: March 2022

The January 2022 eruption of Hunga Volcano, Tonga is likely the most explosive mafic eruption yet documented. It exhibited dynamics of ash plume expansion and atmospheric pressure waves unlike anything seen before. This is remarkable considering that it erupted crystal-poor and microlite-poor andesitic magma (57-63 wt% silica glass). The climactic phase produced an eruptive column of at least 39 km in height, however, the ash volume appears anomalously small for the explosive magnitude. Ash from nine different sites across the Kingdom of Tonga were analyzed for textural and morphological properties and grain size distribution. The tephra comprises light pumice (16%), dark pumice (44%), glassy microlite-rich grains (25%), lithics (7%) and free-crystals (Pl, Cpx, Opx) (8%). Specific gravity of particles range from 0.4 to ~2.5. Secondary electron images show that pumices have a variable vesicularity, from dense glassy blocky particles; glassy particles with isolated vesicles and weakly deformed, thick vesicle walls; and a smaller percentage of microvesicular pumices, coated in finer particles. The general characteristics imply a rapid decompression, fragmentation and chilling. This implies some form of phreatomagmatism but with high-efficiency to generate such a large blast – e.g., via propagation of stress waves and thermal contraction rapidly increasing a magma surface area for interaction. The ash is fine-grained and poorly sorted overall. Less than 20 wt.% of ash particles are >1 mm at 80 km SE of the volcano on the main island of Tongatapu, while 70 km NE of the volcano (Nomuka Island) has finer ash, with only 2% of particles >1 mm. It appears that the dispersion axis for the event was directed toward the E or ESE, across the main population centre of Nuku’alofa on Tongatapu. Of the fine fraction 20 wt.% is < 30 micron, 8 wt.% <10 micron but unusually few particles of very fine range (<0.05 wt.% finer than 1 micron). Variations in the mode and sorting of ash fall at different locations and angles from the vent show that there was potentially complex dispersal of ash from different phases of the 11-hour long eruption, and or different plume heights and fragmentation processes involved. Plume observations suggest at least two different plume levels during main phases of the eruption and the fragmentation mechanisms likely varied from the blast-generating phase and the lesser-explosive phases leading up to and following this.
The global reach of the 2022 Tonga volcanic eruption
Authors: Sepic Jadranka , Medvedev Igor , Fine Isaac , Thomson Richard , Rabinovich Alexander
Published: March 2022

The Tonga volcanic eruption of 15 January 2022 generated tsunami waves that impacted the entire Global Ocean as far away as 18,000 km from the source in the tropical Pacific Ocean. A defining characteristic of the tsunami was the dual forcing mechanism that sent oceanic waves radiating outward from the source at the longwave speed and atmospheric pressure Lamb waves radiating around the globe at the speed of sound (i.e. roughly 1.5 times faster than the longwave phase speed). Based on time series from several hundred high-resolution observational sites, we constructed global maps of the oceanic tsunami waves and the atmospheric Lamb waves. In some areas of the Pacific Ocean, we were able to distinguish between the two types of motions and estimate their relative contribution. A global numerical model of tsunami waves was constructed and results from the model compared with the observations. The modeled and observed tsunami wave heights were in good agreement. The global maps also enabled us to identify regional “hot spots” where the tsunami heights were highest. In addition to areas in the Pacific Ocean (Chile, New Zealand, Japan, the U.S. West Coast, and the Alaska/Aleutian Islands), “hot regions” included the Western Mediterranean and the Atlantic coasts of Europe and northern Africa.
Numerical investigation of hydro-mechanical responses of a single fracture embedded in a porous matrix
Authors: Blöcher Guido , Kluge Christian , Cacace Mauro , Deng Qinglin , Schmittbuhl Jean
Published: March 2022

We have conducted a flow-through experiment using a Flechtingen sandstone sample containing a single macroscopic fracture. Based on this experiment, we obtained range of various intrinsic rock parameters, such as permeability and specific stiffness of the combined matrix-fracture system under hydrostatic loading. In order to quantify the processes behind the laboratory observations, we carried out coupled hydro-mechanical simulations of the matrix-fracture system. Navier-Stokes flow was solved in the 3-dimensional open rough fracture domain, and back-coupled to Darcy flow and mechanical deformation of the rock matrix.

To capture the volumetric shape of the fracture, the two fracture surfaces were scanned using a 3D-profilometer (Keyence VR-3200) before and after the experiment. The resulting fracture surfaces were aligned using a grid-search algorithm and subsequently offset to mimic the shear displacement as applied during the laboratory experiment. Based on the obtained 3D representation of the fracture volume embedded in a porous media, the stress path of the laboratory experiment was simulated numerically. By means of the simulation results, values of fracture closure, increase of contact area, fracture permeability and fracture stiffness due to normal load on the fracture surface were obtained.

The results demonstrate that the numerical simulation could capture the elastic and inelastic behaviour as well as the related permeability alteration of the fracture domain. Both, the laboratory experiments as well as the numerical simulation indicate an inelastic deformation of the single fracture even at low normal stress. The inelastic deformation is expressed by an increase of the fracture contact area and therefore fracture stiffness with increasing stress. The increase in the contact area is due to a reduction in mean aperture and is therefore accompanied by a reduction in the fracture permeability. The development of the contact area is irreversible and thus indicates the maximum stress that the sample previously experienced. We call this behaviour "stress-memory effect".

We present the workflow to obtain the numerical results and a comparison with the laboratory experiment to show that the dominant processes were captured by the simulation.
Balancing sediment connectivity and energy production via optimized reservoir sediment management strategies
Authors: Tangi Marco , Bizzi Simone , Schmitt Rafael , Castelletti Andrea
Published: March 2022

Dam development projects cumulatively alter natural river connectivity, e.g., for fish and sediment, resulting in cumulative negative externalities across different spatio-temporal scales. Strategic siting of dams combined with dam-scale management, e.g., drawdown flushing for sediment passage, can help mitigate these impacts.

Designing optimal reservoir management strategies for multiple dams (i.e., dam portfolios), which account for economic objectives as well as sediment connectivity, is rarely done due to the lack of specifically designed modelling tools to properly quantify the hydro-morphological response of river systems to water and sediment management schemes. Models designed for this purpose must retain both a basin-scale perspective (to capture cumulative impacts of multiple dams) and a dynamic time representation (to capture dynamic reservoir operations).

This work presents a novel approach to reduce trade-offs between hydropower and sediment through integrating both optimal site selection and optimized joint operation of selected dam sites for sediment flushing. To estimate basin-wide sediment delivery and transport and quantify the effect of reservoirs on it, the study uses a new version of the D-CASCADE model, a process-based basin-scale dynamic sediment transport model.

The study focuses on the 3S river system, a data-scarce tributary of the Mekong river, where major dam development is ongoing. First, (1) the D-CASCADE model is set up and compared to available evidence of grain sizes and transport rates in the network. Then, (2) the effect of reservoir management is explored for different, pre-defined dam development portfolios focusing on downstream reservoirs, assessing daily sediment transport and delivery. Reservoirs features (i.e., volume, energy generation, and sediment storage) are dynamically simulated via integrated modelling add-ons. Finally, (3) sediment management (through drawdown flushing) is optimized by including parameters specific to the timing, frequency, and design of drawdown flushing into the operation rules.

Modelled network sediment yields matching field data measurements are identified and used as a baseline scenario to which to compare dam impacts on sediment delivery. Without sediment management, the model estimates a reduction in network sediment yield to the Mekong river of 32%-57%, depending on the dam portfolio. Sediment management portfolios showcase how reservoir sedimentation and downstream sediment starvation can be mitigated via well-designed flushing operations, albeit at a non-indifferent loss in energy production.
Sediment Response to Deforestation within the Amazon River Basin
Authors: Narayanan Anuska , Cohen Sagy
Published: March 2022

The Amazon River Basin is the largest river system in the world, accounting for one-fifth of global freshwater discharge and supplying 40% of the Atlantic Ocean’s sediment flux. Though the Amazon is most often recognized for its rich biological diversity, it also performs a suite of ecosystem functions such as river flow regulation, local climate modulation, and carbon sequestration. Despite its ecological importance, the Amazon experiences thousands of kilometers of deforestation annually with recent rates increasing to levels unseen since the late 2000s. These increased rates of deforestation within the basin have led to changes in sediment concentration within its river systems, affecting not only the ecological balance within the system but also the availability of water to those dependent on river flows. Furthermore, sediment plays an important role in river channel morphology and landscape development, effectively influencing the future topography of the basin. Therefore, it is important to closely examine the relationship between deforestation and suspended sediment in order to characterize the extent of influence anthropogenic activities, such as deforestation, have on rivers.

In this study, we analyze the impact of deforestation from 2001 to 2020 on suspended sediment throughout the Amazon River Basin. These effects are studied by quantifying the spatiotemporal relationships between observed suspended sediment (at gage sites and using a basin wide remote sensing product) and changes in land cover over time. We hypothesize that deforestation will lead to significant increases in suspended sediment flux in adjacent streams and that the effect of deforestation on suspended sediment flux will decrease significantly downstream. 
Using fluorometric techniques to quantify microplastic transport in an experimental flume
Authors: Boos Jan-Pascal , Gilfedder Benjamin , Frei Sven
Published: March 2022

Rivers and streams are a primary transport vector for microplastics (MPs), connecting terrestrial sources to marine environments. While previous studies indicated that pore-scale MPs can accumulate in streambed sediments, the specific MPs transport and retention mechanisms in fluvial systems remain poorly understood. We present a novel method for a quantitative analysis of the spatiotemporal transport and retention of pore-scale MPs in an experimental flume. A continuous mass balance for MPs in surface water was achieved using two online fluorometers, while a laser-induced Fluorescence-Imaging-System was developed to track and quantify the spatial migration of MPs through the streambed sediments. The detection limit was <1 μg/L for 1 μm polystyrene microbeads with the fluorometers and 3 μg/L for the Fluorescence-Imaging-System. The system was able to quantitatively track the advective transfer of MPs into the streambed sediments: a process that has yet not been observed experimentally. Results showed that MPs infiltrated into the streambed sediments up to a depth twice the bedform amplitude. This work provides a novel experimental method to quantitatively monitor MP transport through porous media and advective exchange of MP across the streambed interface.
Barite reactivity at solubility equilibrium as a function of [Ba2+]/[SO42-] ratios
Authors: Zhu Chen , kang Jinting , Bracco jacky , gong Lei
Published: March 2022

We carried out 137Ba and 34S-spiked experiments and measured barium attachment and detachment fluxes from and to barite crystal surfaces in solutions at solubility equilibrium with barite. The [Ba]/[SO4] ratios in solutions varied from 0.06 to 52. Both attachment and detachment fluxes increase with [Ba]/[SO4] ratios. As expected, since the solutions were near solubility equilibrium ( ), the attachment and detachment fluxes were nearly equal and net fluxes or reaction rates were zero.

The isotope flux data together with step velocity data from AFM studies by Kowacz et al. (2007) were simultaneously fit into the Zhang and Nancollas (1998) process-based AB crystal growth model, which describes crystal growth and dissolution through nucleation and propagation of kink sites. The Newton Conjugate Gradient Trust Region algorithm was used for simultaneously and optimally regressing both attachment and detachment rate coefficients. Simultaneous fitting step velocity data of Kowacz et al. (2007) significantly reduced the number of non-unique solutions. The excellent agreement indicates that attachment and detachment fluxes and step velocity are consistent and complement each other.

The results of this study demonstrate significant isotopic changes in solutions and solids from mineral-fluid interactions at solubility equilibrium. The Zhang and Nancollas (1998) model has been used as a foundation for interpreting isotopes and trace element data. Our results therefore have significant implications for extending it to the understanding in diagenetic and low temperature metamorphic processes.
Searching for Mid-Mantle Water with Multitaper-Correlation SS Precursors
Authors: Frazer William , Park Jeffrey
Published: March 2022

Earth’s mantle transition zone (MTZ) is a possible global water reservoir and may be responsible for long-term (~100 Ma) ocean-mass regulation, driven by plate tectonics and mantle convection. Estimates of MTZ mineral water capacity exceed 1 wt%, far greater than that of rocks of either the upper- or lower-mantle. When water-rich material from the transition zone penetrates the upper or lower mantle, partial melting occurs due to the decrease in water capacity after phase transition, generating a reduction in seismic velocities. This process can add an additional low-velocity zone (LVZ) that can be imaged above(below) the 410(660)-km discontinuities, if melt is present. Depending on the melt fraction and wetting angle at mineral-grain boundaries, decreases in shear velocity of 0.5-2.6% can be generated. Seismic receiver functions have detected velocity reductions both above and below the MTZ, interpreted to be partial melting induced by high water content under the Alpine orogeny, in the deep Japan-slab subduction zone, and across the western United States. Since much of Earth lacks seismic stations, we apply SS precursors to conduct a global survey for such LVZs. The precursors to the SS phase reflect off interfaces near the source-receiver midpoint, so seismic stations are not required to be located above the target region. Detection and interpretation of LVZs surrounding sharp positive-velocity gradients, such as the 410- or 660-km discontinuity, is often complicated by side lobes, an artifact of common signal-processing routines. To address this challenge, we develop an SS precursor method based on the multitaper-correlation (MTC) technique. MTC allows for analysis at higher frequency, leading to finer depth resolution, and can increase the number of useful data records. We conduct MTC SS-precursor analysis for seismic waveforms recorded on the ~125 stations of the Global Seismographic Network to benchmark our new method and search for LVZs. Results will be compared to LVZs interpreted from previous seismic analysis.
First order reversal curves (FORCs) as indicators of magnetic PM sources 
Authors: Sheikh Hassan Aftab , Harrison Richard John
Published: March 2022

Real-time monitoring of particulate matter (PM) is performed by traditional air quality monitors using size-fractionated light-scattering laser photometers or gravimetric analysis. However, these quick methods do not fully characterise the particulates, in particular, the more toxic metals such as Fe. Here, we propose the use of first order reversal curves (FORCs) as a method to discriminate different sources of anthropogenic magnetic particles. FORCs is a useful magnetic characterisation technique that is sensitive to particle size, mineralogy and domain state. By measuring known sources of particulates, we hope to come up with a ‘magnetic’ proxy in a heterogenous source of PM in the air using principal component analysis (PCA). FORC fingerprints for exhaust, non-exhaust vehicular sources, resuspended dust and train-related PM are distinct, providing a cost-effective way to monitor relative proportions in the ambient air. The first set of specimens involved measuring FORCs on known, size-fractionated brake abrasion dust on an accelerating gradient magnetometer. Processed FORCs for brake dust residue specimens show a distinct combination of narrow central ridge, extending from 0 to up to 200 mT, and a low-coercivity, vertically spread multi-domain signal. Similarly, known exhaust-pipe residue samples were measured, displaying a more conventional ‘magnetite-like’ signal comprising a lower coercivity central ridge (0-80 mT) and a tri-lobate signal attributed to vortex state and/or magnetostatic interactions. Tyre and road wear samples are generally low-coercivity and vertically spread, hinting at mostly coarser, resuspended dust that has settled down. Third set of data involved measuring gravimetric specimens from London Underground. The source of magnetic particulates in fundamentally the same but different ventilation rates on platforms meant the ‘fingerprints’ were different. Principally, FORC fingerprints are sensitive to grain size, mineralogy and total magnetic content, demonstrating a low-cost approach for identifying different proportions of magnetic particulates. These data will be complemented by measurements with high-resolution microscopy such as TEM and EELS to characterise the magnetic state of particulates and add value to conventional air quality monitoring systems.
Open and collaborative science: 4+ years of going to the extreme
Authors: Schymanski Stanislaus J. , Ceolin Samuele , Corvi Oscar , Gama Adriano , Krieger Louis , Minette Frank , Nijzink Remko C. , O'Nagy Oliver , Osuebi-Iyke Emmanuella , Thakur Gitanjali
Published: March 2022

The goals of open science include easy reproducibility of research results, transparency of research methods and re-usability of artefacts, e.g. data, code, and graphics. Consequently, open science is expected to foster scientific collaboration and sustainability of research, as it enables building on each others' methods and results for many years and decades to come.

Here we report about our collective attempts in the last 4-10 years of taking open science to the extreme by using exclusively open formats, open-source software, sharing all stages of our work online and recording workflows and provenance of code and data. Most of our analyses are carried out in Jupyter Notebooks, which are all shared online through gitlab. In these notebooks and our python-analyses, we integrate the python package essm for transparent and easily reproducible mathematical derivations. For more complex analyses, including large model runs, we use the tool Renku of the Swiss Data Science Center in order to record workflows and provenance of code and data.

Find out where we succeeded, where we failed, what we gained and what we lost in pursuing open science to the extreme. Hear about the views and experiences with open science at the undergraduate, postgraduate, postdoc, engineer and senior researcher level. Eventually, we will also report about what we are still missing for entirely reproducible, verifiable, and reusable open science. We hope we can foster a debate about good open science practices, and how we can remove obstacles that are still in our way.
Relative dispersion and relative diffusivities of model-runs in the North Sea
Authors: Villa Castrillon Luciana , Ricker Marcel , Meyerjürgens Jens , Grayek Sebastian , Staneva Joanna
Published: March 2022

We examined the relative dispersion and relative diffusivities of model-runs in the North Sea for the period Oct-Dec 2018 and Jan 2019. The role of the different wave-induced processes is investigated using a fully coupled (NEMO-WAM) model analysis together with simulations from a particle-drift model (OpenDrift). Coupled model parameterisations account for the feedback between the upper ocean and the waves. The processes that are introduced into the hydrodynamical model are sea state dependent momentum flux, sea state-dependent energy flux and wave-induced mixing. The results are assessed using surface drifter observations and in situ measurements. The analyses of the model skills reveal that the Eulerian currents, produced by coupling wind waves and ocean circulation model and introducing wave-induced parameterisations are essential for improving the particle transport. Further, experiments based on the drifter clusters obtained on the RV Heincke excursion are performed. Experiment 1 contains the initial positions and time taken from the surface drifters. Experiment 2 is the average of the positions in Experiment 1. In addition, diffusivity was considered in OpenDrift to observe its impact on the relative dispersion and relative diffusivity. The results show how turning on the diffusion in OpenDrift makes the curve smoother. There, the Richardson regime, which describes a dispersion following  <img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.481e80392fd164205102461/sdaolpUECMynit/22UGE&app=m&a=0&c=f22e4506b934706b7a3acb260c693d5d&ct=x&pn=gnp.elif&d=1" alt="" width="55" height="18"> , and the exponential growth regime were observed.
Ensemble Kalman Filter based Data Assimilation for Tropical Waves in the MJO Skeleton Model
Authors: Gleiter Tabea , Janjic Tijana , Chen Nan
Published: March 2022

The Madden-Julian oscillation (MJO) is the dominant component of tropical intraseasonal variability with wide reaching impacts even on extratropical weather and climate patterns. However, predicting the MJO is challenging. One reason are suboptimal state estimates obtained with standard data assimilation (DA) approaches. Those are typically based on filtering methods with Gaussian approximations and do not consider physical properties that are specifically important for the MJO.

In our recent paper (Gleiter et al. 2022), a constrained ensemble DA method is applied to study the impact of different physical constraints on the state estimation and prediction of the MJO with the Skeleton model. The utilized quadratic programming ensemble (QPEns) algorithm extends the standard stochastic ensemble Kalman filter (EnKF) with specifiable constraints on the updates of all ensemble members. This allows to recover physically more consistent states and to respect possible associated non-Gaussian statistics. Our results demonstrate an overall improvement in the filtering and forecast skill when the model's total energy is conserved in the initial condition. The degree of benefit is found to be dependent on the observational setup and the strength of the model's nonlinear dynamics. It is also shown that even in cases where the statistical error in some waves remains comparable to the stochastic EnKF during the DA stage, their prediction is remarkably improved when using the initial state resulting from the QPEns.

Gleiter, T., T. Janjic, N. Chen, 2022, Ensemble Kalman Filter based Data Assimilation for Tropical Waves in the MJO Skeleton Model, QJR Meteorol Soc., https://doi.org/10.1002/qj.4245
Reconstructing stress magnitude evolution in deformed carbonates: a paleopaleopiezometric study of the Cingoli anticline (North-Central Apennines, Italy)
Authors: Labeur Aurélie , Beaudoin Nicolas E. , Lacombe Olivier , Petraccini Lorenzo , Callot Jean-Paul
Published: March 2022

Picturing the distribution of stress, in term of magnitude and orientation, during the development of a fold-and-thrusts belt is key for many fundamental and applied purposes, e.g., crustal rheology, orogen dynamics, fluid dynamics and prediction of reservoir properties. Specific meso- and micro-structures observed in fold-and-thrust belts and related forelands (i.e., faults, stylolites, veins and calcite twins), on top of being good markers of the deformation sequence that affected the rocks before, during and after folding and thrusting, can be used to access the past stress orientation and/or magnitude. This study reports the result of a paleopiezometric analysis of calcite twins and stylolite roughness documented in Mesozoic carbonates cropping out in the Cingoli anticline, an arcuate fold in the Umbria-Marche Apennine Ridge (UMAR), where a complex fracturing sequence was highlighted in a previously published study. The stylolite roughness inversion technique (SRIT) was applied to tectonic stylolites related to early folding layer-parallel shortening (LPS), and the calcite twin inversion technique (CSIT) was applied to cements from veins related to either foreland flexure or LPS. Both inversion processes require somehow the knowledge of the depth at which deformation occurred, as the vertical stress is an input for SRIT in the case of its application to tectonic stylolites, and as the differential stress magnitudes obtained by CSIT combined to vertical stress magnitude provides access to the absolute principal stress magnitudes. Building on a previously published time-burial path valid for the studied strata at the Cingoli anticline that also predicted the timing of each deformation stage, we quantify differential and principal stress magnitudes at the scale of the anticline. Beyond regional implications, our approach helps improve our knowledge of the past stress magnitudes in folded carbonate reservoirs.