bluuebunny/crossref_metadata_2025 huggingface dataset:
Middle to Late Pleistocene alluvial surface ages recorded by their spectral reflectance in Patagonia, Argentina.
Authors: Ruby Andreas , Schildgen Taylor , Crawford Henry , D'Arcy Mitch , Fernandes Victoria M. , Wittmann Hella , McNab Fergus , Georgieva Viktoria
Published: February 2023

Alluvial surfaces like fluvial terraces can act as markers for past changes in sediment and water flux along alluvial rivers. By precisely dating terrace surfaces, we can begin to quantify how sedimentary signals propagate though river channels and better infer the paleo-climatic and tectonic conditions during their formation. However, collecting and processing geochronological samples along larger river systems can be costly and time consuming. Here, we extend alluvial landform age control along the Río Santa Cruz of southern Patagonia by applying a spectral surface characteristic model calibrated from a limited set of field samples and cosmogenic nuclide derived exposure ages. This quantitative method leverages the spectral response of surface weathering to ultimately improve age control of the region's fluvial landforms while reducing the time and cost associated with traditional field dating methods.Ages of alluvial surfaces may correlate with time-dependent geochemical weathering processes, such as clay mineral formation. Although previous surface-weathering studies have mostly focused on surface ages since the last or penultimate glaciation, we analyzed the change in weathering state for southern Patagonian fluvial terraces up to a million years old consisting of quarzitic and granitic source lithologies. We find that multispectral Landsat 8 data show a 20% increase in the band 6 to band 2 ratio with terrace elevation (and inferred age), highlighting the higher reflectance in the shortwave infrared band often associated with clay mineral formation. It is likely that weathering rates in the dry and cold Patagonian environment are slower compared to regions with less stable and warmer climate conditions or lithological sources, where age dependent weathering signals in multispectral data tend to saturate on much shorter time scales. Our new 10Be results from surface cobbles and amalgamated pebbles yield exposure ages roughly between 45 and 1000 ka for these surfaces, and the calibrated spectral model allows us to interpolate ages of additional 9 alluvial surface generations based on 11 dated surfaces in the region.Planned in-situ spectral surface measurements will provide robust ground-truthing to the satellite-based observations and allow for further investigation of the mineral changes driving the age-dependent spectral signal. Furthermore, additional terraces will be dated downstream to provide (1) a better understanding of how the weathering process may differ with downstream distance, and (2) a more reliable correlation of surfaces over long distances (> 100 km), enabling us to reconstruct the details of past climate forcing on alluvial-channel evolution.
Continental Scale Landslide Susceptibility Mapping Using Machine Learning Techniques
Authors: Reveley Graham , Mitchell Hamish , Burke Claire , Brennan James , Woodhouse Sally , Ramsamy Laura
Published: February 2023

The identification of areas susceptible to landslides is critical for planners, managers, and decision makers in developing functional mitigation strategies. Recent applications of machine learning and data mining methods have demonstrated their effectiveness in large-scale assessments of landslide susceptibility. At Climate X, we utilise a range of big Earth remote sensing data alongside machine learning techniques to evaluate the spatial susceptibility landslides at continental scale. We compile several conditioning factors— including topographic, subsurface, and land use data—and combine them with continental scale landslide inventories to generate landslide susceptibility maps for Europe and North America. Climate model projections for different emissions scenarios are then used to understand how climate change could modify the spatial occurrence of landslide events with a focus on landslides triggered by rainfall within steeper terrain. Our results demonstrate how the combined application of big Earth data and machine learning can provide time sensitive assessments of landslide hazard over large spatial scales.
Topographic Effect of the Antarctic Peninsula on Strong Wind Event at the King Sejong Station
Authors: Kwon Hataek
Published: February 2023

The topographic effect on the strong wind event occurred on 7 January, 2013 at the King Sejong Station (KSJ), Antarctica was investigated using the Polar Weather Research and Forecasting (WRF) model. Numerical experiments applying three different terrain heights of the Antarctic Peninsula (AP) were performed to quantitatively estimate the topography effect on the selected strong wind event.
The experiment employing original AP topography successfully represented observed features in strong wind, both in terms of peak wind speed by around 94% (~19.7m/s) and abrupt transitions of wind speed. In contrast, the experiment with a attened terrain height signicantly underestimated peak wind speeds by around 51% (~10.4m/s) of observations. An absence of AP topography failed to simulate both a strong discontinuity of sea-level pressure elds around the east coast of the AP and a strong southeasterly over the AP. As a result, the observed downslope windstorm, driven by a ow overriding a barrier, was not formed at the western side of the AP, resulting in no further enhancement of the wind at the KSJ station. This result demonstrates that the topography of the AP plays a critical role in driving strong wind at the KSJ station on 7 January, 2013, accounting for approximately 50% of the total wind speed.
Depositional patterns of microplastics in a meandering river: a case study of the Leie River, Belgium
Authors: Van Daele Maarten , Van Bastelaere Ben , Vercauteren Maaike , Meyer Inka , Asselman Jana
Published: February 2023

Following the discovery of microplastics (MPs) in river sediments, the number of MP studies on rivers and other freshwater systems has increased rapidly, revealing that MPs are omnipresent in all freshwater environments. The abundance of MPs in freshwater sediments seems to be affected by population density, urban centers, water flow velocity, water catchment size and position and type of sewage and waste management. However, not all of these relations are consistent. For example, while many studies report good correlations between MP source regions (highly populated and industrialized areas) and MP abundance in river sediments, others do not. This is in contrast to the concentrations in the water itself, for which better links with MP source areas were found. What all these studies have in common, is their large-scale approach, in which sediment samples are obtained over distances of tens to thousands of kilometers along the river; and at each site sediments are than retrieved either from the deepest part of the channel or from the river bank (depending on the study). Here, we study MP distribution in a section of the meandering Leie River, in a rural area, a few kilometers upstream of the city of Ghent (Belgium). Multibeam bathymetry and side-scan sonar images allowed selecting three undisturbed across-channel transects where surface sediments were retrieved. Sediment samples were analyzed for MP content, organic-matter content and grain size of the clastic fraction. Overall the MP concentrations are much (up to an order of magnitude) lower in the thalweg compared to samples near the river banks, resulting in an asymmetric distribution at the bend apex, where the thalweg approaches the outer banks. Furthermore, MP concentrations show strong correlations with the organic matter content and grain-size parameters as expected form hydrodynamic sorting. Exceptions to these correlations are the outer bank samples, where MP concentrations are lower than predicted from sedimentological characteristics. We attribute this to the more erosive character of the current in the thalweg near the outer banks, which inhibits MP deposition, but exposes fine-grained and organic-rich flood plain sediments. We highlight that the different hydrodynamic conditions across a river channel greatly influence MP distribution (with an order of magnitude), but in a sedimentologically predictable manner. Care should thus be taken in environmental studies, as local variability in MP concentration across a river bed may be larger then the large-scale variability.
A new web-based and open data reduction application to determine Fe2+/Fe3+ ratios using the electron microprobe flank method.
Authors: Hezel Dominik C. , Höfer Heidi E. , Fichtner Andreas
Published: February 2023

The electron microprobe (EPMA) flank method can be used to determine in-situ the Fe2+/Fe3+ ratios in garnet [1], and potentially also in other minerals. It is a tool to reveal the redox history of rocks, especially when the garnet grain size or garnet homogeneity requires a microanalytical technique for Fe3+/Fe(tot) determination (e.g., [2,3,4]). The flank method is based on the accurate intensity measurement at two positions on the flanks of the FeLa and FeLb emission lines, and makes thus use of the systematic change of the intensities and wavelengths of the FeL lines with: (i) the iron oxidation state and (ii) the total iron content.  Data reduction of the obtained data so far required a complex combination of numerous Excel spreadsheets, and, for multiple linear regressions, the conversion to text files in combination with the Matlab clone Octave. This work-flow required a trained expert, and could quickly take up to even several days. We converted this process into a web-application with a simple and intuitive graphical user interface (GUI), with which the entire work-flow can be completed within minutes to hours. The web-application uses the 2-dimensional linear regression fit to determine Fe2+ from its dependency both on the intensity ratio FeLb/FeLa and the total Fe content, based on eq. 2 in [1].  The web-application allows the visual examination of all data using a large variety of plots for in-depth data inspection. Video tutorials embedded on the website explain not only how to use the website, or how the data reduction itself works, but also the flank as well as the EPMA method itself. Own data can be uploaded and reduced, and an available demo dataset allows training and exploring the web-application.The entire web-application is realised using Python, Streamlit and a public GitHub repository. We will present what the flank method is, how it works using the EPMA, how the data reduction process works, and demonstrate how to use the web-application from the raw dataset to the final results.[1] Höfer H. E. and Brey G. P. (2007) The iron oxidation state of garnet by electron microprobe: Its determination with the flank method combined with major-element analysis. Am Mineral 92, 873–885.[2] Wang C, Tao R, Walters JB, Höfer HE, Zhang L (2022): Favorable P–T–ƒO2 conditions for abiotic CH4 production in subducted oceanic crusts: A comparison between CH4-bearing ultrahigh- and CO2-bearing high-pressure eclogite. Geochim. Cosmochim. Acta 336, 269-290[3] Tang M, Lee C-TA, Costin G, Höfer HE (2019): Recycling reduced iron at the base of magmatic orogens. Earth and Planetary Science Letters 528, 115827. doi.org/10.1016/j.epsl.2019.115827[4] Aulbach S, Höfer HE, Gerdes A (2019): High-Mg mantle eclogites from Koidu (West African craton): Neoproterozoic ultramafic melt metasomatism of subducted Archaean plateau-like oceanic crust. Journal of Petrology 60, 723-754
The use of stable pore water isotopes in the study of nitrate leaching
Authors: Lobina Francesca , Da Pelo Stefania , Stumpp Christine , Arras Claudio , Biddau Riccardo , Coppola Antonio , Vacca Andrea
Published: February 2023

In recent years, with the development of intensive farming and livestock breeding activities, nitrate contamination of aquifers has occurred. The importance of the unsaturated zone in the study of nitrate percolation is well recognized. The vadose zone represents a fundamental part of the water cycle, capable of storing water, providing water for vegetation, transporting solutes and degrading contaminants before they reach the aquifer.This research involves two areas with different geological, hydrogeological and pedological properties located in Sardinia. The plain of Arborea has been designated as Nitrate Vulnerable Zone (NVZ) since 2005, but despite the reduction of nitrogen input no significant improvement in water quality has been achieved. In the Southern Campidano plain, an area with an agricultural tradition, significant nitrate concentrations were observed in groundwater.The main objective of this research is to estimate the groundwater recharge rate using vadose-zone water stable isotope profiles.Firstly, to understand the dynamics of water percolation through the vadose zone, soil samples were collected at different depths to analyzed for physical properties, including soil-water content, and grain size to estimate soil hydraulic properties. In addition, suction cups were installed at different depths at each site to extract pore water from the soil for chemical analysis.In hydrological systems, the use of stable isotopes (18O and 2H) of pore water as environmental tracers is considered the most useful tool for establishing water flow and contaminant transport. In this study stable pore water isotope profiles combined with water content profiles were used to obtain insight into the transit time of water percolating through the vadose zone. At each of the two study sites, vertical soil sampling was made along the vadose zone and the soil samples collected were analyzed for stable water isotope ratios (18O and 2H) and volumetric water content. Through the seasonal signatures of stable isotopes in leachate water it is possible to quantify possible groundwater recharge, this approach, called the peak-shift method assumes advection-dominated transport.Analysis of nitrate concentrations in soil water below the root zone using suction cups combined with groundwater recharge rates will allow an estimate of site-specific nitrate leaching. Through this approach, it is possible to evaluate potential and conservative propagation of nitrogen at specific depths to be compared with the concentrations measured to gain information on nitrate transformation processes in the soil.
Estimations of the Ocean Wave Heights using terrestrial seismic data
Authors: Baranbooei Samaneh , Bean Christopher J.
Published: February 2023

Traditionally, there are different approaches to monitoring the ocean wave field consisting of 1) measurements using insitu buoys, 2) numerical ocean wave modeling using wind forecast, and 3) satellite altimetry. Each of these ocean wave monitoring techniques has their own advantages and disadvantages associated with their spatial and temporal resolution. For example, buoys are physical point measurements with excellent temporal resolution (e.g., sub-hourly), but their spatial resolution is very poor (e.g., a single point in space). Buoys are also expensive to maintain; ‘Real-time’ wave height estimations from numerical wave modeling is based on forecast wind, hence the model accuracy is dependent on wind prediction accuracy.  Compare to buoys, the temporal resolution of available outputs from large-scale numerical models is usually low (e.g., every 3 hours), but the spatial resolution is much better (various resolutions depending on the grid size); Satellite altimetry looks over a large region so the spatial coverage is very good but the temporal resolution is very poor (e.g., once every four days). In this work, we consider terrestrial seismic (microseism) data as a proxy for wave heights. Under certain conditions, it has the potential for combined good spatial and temporal resolution, in quasi-real time.  This technique is based on the relationship between secondary microseism amplitudes recorded on land and the ocean wave-wave interactions which excite the sea floor, generating these secondary microseisms.  Here we take a data-driven approach, implementing an Artificial Neural Network (ANN) to quantify the complex underlying relationship between ocean wave height and microseism amplitude. Thus far we trained the ANN using the available seismic and numerical simulated data and then used the trained ANN to estimate significant Ocean Wave Height (SWH) at a particular location(s) in the Northeast Atlantic using amplitudes from seismic stations distributed across Ireland.Our preliminary results look very promising and show relatively small residuals for measured wave height using the ANN compare to the real buoy data for both small and moderate wave heights.  However, currently larger residuals are seen for the largest ocean wave heights. We expect this to improve as ever more data becomes available.  
A methodology for integrating community acceptance of wind energy into energy system modelling (ESM)
Authors: Velasco Herrejón Paola , Zeyringer Marianne , Winther Tanja , Schmidt Johannes
Published: February 2023

Decarbonisation of the energy system is key to achieving the Paris Agreement goal of limiting global temperature rise to below 2°C which can be achieved by electrified and interconnected systems with a high share of variable renewables. This transition is shaped by uncertain factors, which include technology innovation, resource availability, and socio-economic variables. Energy system modelling (ESM) has been a key policy tool to study decarbonisation pathways. ESM provides stakeholders in the energy sector with knowledge-based and systematic methods to reach decisions about which technologies to support. However, present-day ESM mainly integrates techno-economical input parameters, whereas social factors, such as local responses to new installations, are largely understudied. ESM might therefore produce solutions that are not accepted by communities and as a result, could jeopardize energy transition goals. The main goal of this presentation is to present the framework for WINDACCEPT, a Horizon Europe project that aims to develop an innovative and interdisciplinary mixed-methods approach integrating concepts of sociology (stakeholder analysis), economic philosophy (capability approach), and technology systems (energy systems modelling) to better define the ‘real world’ feasibility of large-scale wind farms from a range of economic, political, regulatory, and societal perspectives. This new methodology will be developed and applied to the case of Norway, a country with excellent wind resources but high local opposition towards their development. The selected case study is NVE area No. 40 which includes the municipalities of Hasvik, Hammerfest, Måsøy, Kvalsund, Alta, Porsanger, and Nordkapp. This case study was selected to provide deep knowledge of the context of wind energy social barriers in Norway based on the following factors: 1) excellent wind power conditions, 2) (partly) considered by the NVE as a suitable area for wind power development based on social and environmental factors, 3) a zone where three major RE have been cancelled, and 4) a Sámi area. The methodology aims to contribute to elucidating the impacts of community barriers and value the costs and benefits of alternative options on the net zero energy system design in Norway and the effects on long-term, whole system decarbonisation in an interconnected Europe. The proposed framework will also aim to maximise techno-social synergies that provide beneficial relationships between technological and social systems to increase the social sustainability of RES.
Comparison between DTRT and GEOsniff TRT methods for thermophysical characterization of the ground
Authors: Galgaro Antonio , Visentin Alessandro , Stella Alberto , Di Sipio Eloisa , Dalla Santa Giorgia
Published: February 2023

The research is oriented to provide elements of knowledge, useful for the choice of new generation methods of in situ thermal characterization of the subsoil, which may be more suitable to provide quantitative information on the design and sizing parameters for closed-circuit heat exchange systems. In particular, it is essential to determine the thermal resistance of the ground heat exchanger as well as the ground undisturbed temperature and the thermal conductivity of the ground affected by the heat exchange processes, being able to differentiate the contributions of the different geological levels crossed by the ground heat exchanger. These on-site tests are necessary to design the system and determine the thermal characteristics of cement mixtures to be apply to finally sealing the wells in which the ground heat exchangers are installed.This paper analyzes and compares the results obtained from two different on-site thermal response test methods, carried out to design a borefield of a GSHP plant, foreseen in the renovation project of the Swiss Embassy in Italy in Rome (RM). The boreholes reach a depth of 200m and are installed in a geological context characterized by volcano-clastic deposits. In particular, two methods of distributed investigation of subsoil temperature and thermal properties are compared. The two methods are based on different technologies: optical fiber heating cable (DTS) and an innovative method that uses smart spheres ("GEOsniff"- enOware) floating inside the boreholes, integrated with miniaturized electronics, able to measure the temperature of the water inside the tube all along the whole vertical. Both tests were carried out closed in time and in the same borehole heat exchanger. In particular, the fiber optic DTS (Distributed Temperature Sensing) technology, based on hybrid fiber optic cable and heating wire, performs a distributed thermal response test (DTRT) in one of the vertical geothermal exchangers. The "enOware GEOsniff" technology, based on special sensors and heating cable, was realized 2 months after, to perform a second advanced distributed thermal response (E-TRT) test in the more than one vertical geothermal exchanger.In addition, thermal conductivity measurements and laboratory characterizations were carried out on 4 samples acquired from the corings derived during the drilling operations, thus providing specific values of thermal conductivity of the different levels.The thermal conductivity values obtained in different ways are directly compared and discussed.
An experimental study of the role of ions at modulating the early stages of calcium carbonate formation
Authors: Ruiz-Agudo Encarnacion , Ruiz-Agudo Cristina
Published: February 2023

In the last decades numerous studies have shown that most calcifying organisms build their shells and skeletons via non-classical crystallization processes, including the formation of transient, metastable amorphous calcium carbonate (ACC) as a precursor phase. Although a significant progress has been achieved at understanding CaCO3 growth via amorphous precursors, there are still aspects that remain unexplored. Knowledge of the role of different elements that are commonly co-precipitated with carbonates at modulating the early stages of calcium carbonate formation and the amorphous to crystalline transition is needed to constrain biomineralisation processes and to allow the understanding of how sensitive calcification is to past, current, and future environmental change. In order to address this issue, we investigated the incorporation of boron and magnesium into ACC precipitated under different pHs. This study evaluates the influence of B and Mg on the stability and water content of ACC and its formation mechanism. This information, together with an analysis of the B and Mg content of ACC formed at different pH conditions, provide insights into the factors controlling the chemical signatures and properties of the carbonate polymorphs formed via the ACC pathway.
Characterizing the fire regime evolution and land-use change in the Dry and Wet Chaco between 2001 and 2019
Authors: San Martin Rodrigo , Ottle Catherine , Sörensson Anna
Published: February 2023

Wildfires play an essential role in the biogeophysical cycles of different world ecosystems, from dry savannas to humid wetlands. During the last decades, fire regimes of several global regions began to present significant alterations due to climate change and human land-use pressure. The South American Gran Chaco ecoregion contains one of the most important reservoirs of native forests and biodiversity in the world, including the largest continuous dry tropical forest and some of the most extensive wetlands. The area presents a marked precipitation gradient from the East (wet) to the West (dry), which is manifested in vegetation (from wetlands to dry forests and shrublands). In this work, we mapped natural vegetation with the European Space Agency (ESA) Climate Change Initiative (CCI) medium-resolution land cover maps (MRLC v2.0.7; annual - 300m) and fires with the ESA CCI Fire product (FireCCI51; monthly - 250m) in the Gran Chaco between 2001 and 2019 to establish the past and current effects and dynamics of fires in the area (which are primarily human ignited). To assess the region’s climatology, we used the ERA5 bias-corrected reanalysis dataset (WFDE5; daily - 0.5º). Our results highlight the distinct dynamics of fires in the wet and dry areas of the Gran Chaco, showing two fire seasons - summer and winter - in the wet areas (where grasses predominate) and one fire season - winter - in the dry areas (where shrubs and trees are more abundant). Examining the correlations between annual rain anomalies and burnt area, we find that precipitation anomalies have different effects in dry and wet areas throughout the region’s precipitation gradient. Correlations change from positive in the drier areas to negative in the wetter areas. These results may reflect that summer and winter fires do not have the same drivers and the key role of the available biomass limiting the fire expansion. Since biomass is more dependent on precipitation in dry areas compared to wetter ones, the correlation of winter fires with precipitation is positive in the drier regions. The negative correlations obtained in the summer season could be explained by the fact that summer fires essentially occurred in the wetter part of the Chaco and are intended (through human ignition) to increase the grasslands’ productivity; this practice could be more frequent during negative precipitation anomalies compared to positive ones. Further analysis will try to confirm these findings with biomass satellite data.   
Precipitation of light elements from Earth’s liquid core: Can exsolution power the ancient geodynamo?
Authors: Wilson Alfred , Pozzo Monica , Alfè Dario , Walker Andrew , Pommier Anne , Greenwood Sam , Davies Chris
Published: February 2023

Earth’s core currently sustains a geodynamo through chemical convection in the liquid outer core. This power source originates from the growth of the solid inner core, where light elements are partitioned to the liquid at the lower most outer core. The inner core is expected to be ~1 Gyr old, meaning that for most of Earth history, the geodynamo required alternate power sources to produce a magnetic field. The paleomagnetic record shows that the field has been persistent for the last 3.5 Gyrs. Secular cooling is not capable of providing sufficient power for the geodynamo to remain active during this time if conductive heat transport is large. Recent experiments and calculations find that the thermal conductivity of the core is high, suggesting that the power available for geodynamo action would have been exhausted significantly before inner core growth began. Of the alternate power sources available to supplement secular cooling, precipitation of light elements is the most hopeful. We explore the solubility of silicon and other candidate light elements in iron-rich liquids of the core through ab initio calculations of partitioning. We apply these results to a thermodynamic model of partitioning, informed by experimental partitioning. When incorporated into thermal history models of the deep Earth, we find that the geodynamo can be sustained by silicon precipitation, provided that the oxygen concentration of the ancient core is less than 1.1 wt%. These results highlight the importance of the initial composition of the core and interaction between light elements on the available precipitative power in the core.
Integrated post-event survey of the record-breaking Central Italy flash flood of September 2022: observation strategy and lessons learned
Authors: Borga Marco , Marchi Lorenzo , Gabellani Simone , Morra Di Cella Umberto , Fagugli Giacomo , Libertino Andrea , Brocchini Maurizio , Ballio Francesco , Molinari Daniela , Comiti Francesco , Massari Christian , Fiorucci Federica , Dallan Eleonora , Marra Francesco , Cavalli Marco , Crema Stefano , Rocca Jacopo , Coviello Velio , Saretta Alessandra , Solari Luca ,   central Italy 2022 flash flood post event survey team
Published: February 2023

Spatial and temporal scales of occurrence of flash floods, combined with the space and time scales of conventional measurement networks of rain and discharge, make these events particularly difficult to observe. The effective documentation of flash floods requires therefore post-flood survey strategies encompassing accurate radar rainfall estimation, indirect reconstruction of peak discharges, field observations of the geomorphic processes and large wood dynamics associated. This also provides ground for quantifying, analyzing and interpreting impacts on communities, infrastructures and ecosystems.This work describes the methods applied and the early results achieved with the survey of the exceptional flash flood that hit the Marche region (Central Italy) between the 15th and 16th of September 2022, with rainfall reaching cumulated local peaks exceeding 400mm and recurrence interval exceeding 500 years for certain rainfall durations. The flood occurred at the end of a climatic anomaly of prolonged drought and warm conditions over Europe and the Mediterranean region, and caused 12 fatalities and severe damages to activities and buildings.The documentation of the flash flood reveals high peak flood discharges and a complex flood response. Peak discharges were estimated at 12 cross sections in the upstream sector of the affected river basin, with drainage areas ranging from 4 to 120 km2 and specific flood peaks exceeding 20 m3/(s km2).Among the lessons learned from the field study of this flash flood we underline: i) the need to properly represent the drought history to describe the actual antecedent soil moisture status, ii) the highly variable interaction of flood flows with floating large wood elements trapped at bridges, iii) the need of integrating the documentation of both hazard, impacts and vulnerability aspects to advance models for more effective flood risk management.
The Use of Leucosome Patterns in Migmatites to Decipher Rates of Melt Production, Melt Percolation and External Deformation: Insights from Numerical Modelling
Authors: Fedrizzi Giulia , Piazolo Sandra , Koehn Daniel , Pegler Sam
Published: February 2023

Melt production and migration are important phenomena in the lower and middle crust. The presence of melt in a volume of rock has a significant impact on its rheology and on the structure of the Earth’s crust in general. Once partial melting starts, the molten portion can either flow towards shallower crustal levels or stay in the area where it originated. A partially molten rock can eventually solidify and be brought to the Earth’s surface, where the distribution of the former melt can provide insight into the conditions in which the rock formed.Here we present a set of numerical experiments utilising an innovative DEM-continuum model to simulate partial melting and the initial formation of porosity channels. This hybrid model incorporates porous flow to solve for pervasive percolation of melt and a network of springs on a second grid to represent the linear elastic behaviour of the host rock. The latter also includes phenomena such as fracture formation and propagation.We show under which conditions melt-filled fractures can emerge from local areas of melt production and evolve into larger melt channels. Importantly, our models show that leucosome patterns seen in outcrops can be used to constrain the relative rates of melt diffusion along grain boundaries, syn-migmatisation deformation, and local melt production. Based on the relative rates of these processes, we define regimes with specific melt pattern distributions. The definition of these regimes can be a useful tool for the interpretation of the history of a migmatite.
On the role of antecedent meteorological conditions on soil moisture flash drought initialization in Europe
Authors: Shah Jignesh , Kumar Rohini , Rakovec Oldrich
Published: February 2023

Flash-droughts events are characterized by the fast depletion of soil moisture in the top soil layers. Given their rapid onset and intensification, flash droughts entail severe impacts on ecosystem productivity. Thus understanding their initialization mechanisms is important for improving the skill of drought forecasting systems. Here, we examined the role of antecedent meteorological conditions that lead to flash droughts across Europe over the last 70 years (1950--2020). We found two major flash-drought types based on sequence of development of antecedent hydro-meteorological conditions. The first one is characterized by a joint occurrence of two mechanisms, a continuous decline of precipitation in conjunction with an increase of the evaporative demand, both occurring before the onset of a flash drought event. The second type, on the contrary, is characterized by high precipitation preceding the start of the event followed by a sudden precipitation deficit combined with an increase in evaporative demand at the onset of the drought. Both drought types showed increased occurrence and higher spatial coverage over the last 70 years, the second drought type have increased at a much faster rate compared to the first one specifically over the Central Europe and the Mediterranean region. Overall our study highlights the differences between the two types of flash droughts, related to varying antecedent meteorological conditions, and their changes under recent climate warming. 
Analysis of spatial and temporal evolution of the Brienz/Brinzauls deep-seated landslide, Switzerland
Authors: Manconi Andrea , Bühler Yves , Stoffel Andreas
Published: February 2023

Large compound landslides show long-term evolution, which is characterized by non-steady velocities, sudden accelerations and potential failure events. Accurate data is hence important for the analysis and the interpretation of their kinematic behavior, as well as associated hazard potential. Remote sensing techniques have demonstrated to be a valid complement to standard in-situ monitoring. Here we show how frequent acquisitions with remote Remotely Piloted Aircraft Systems (RPAS) can be used to study large landslide complexes. We performed an extensive analysis at the Brienz/Brinzauls landslide complex, located in canton Graubünden (Switzerland), based on 20 photogrammetric flights acquired between 2018 and 2023. Dem-of-Differences (DoD) and displacements from Digital Image Correlation (DIC) are computed to reconstruct the spatial and temporal evolution of the surface changes. We compare the results with independent monitoring data, and we perform a strain analysis to highlight areas of strain accumulation and identify possible relationships between kinematic domains, geological boundaries, as well as tectonic structures and rock mass discontinuities. The aim of this contribution is to demonstrate how spatial and temporal resolution of the datasets might deeply influence the interpretation of displacements in complex landslide scenarios.
Equilibrium-disequilibrium textures and mineral chemistry of lavas from the Cumbre Vieja 2021 eruption, La Palma, Canary Islands, Spain: insights into magma plumbing systems under intraplate ocean islands
Authors: de Ignacio Cristina , Real Elena , Martín-Crespo Tomás , Gómez-Ortiz David , Martín-Velázquez Silvia , Arnoso José , Montesinos Fuensanta
Published: February 2023

La Palma is one of the youngest and the most active island of all the Canary archipelago, with a total of seven subaerial eruptions over the last 500 years. This magmatic activity is linked to the undergoing growth and development of the youngest volcanic complex in the island: the Cumbre Vieja edifice, a 20 km long and 1950 m high, north-south trending ridge with aligned volcanic cones and fissures forming its summit and flanks. The youngest of them is the Tajogaite volcanic vent, which is located in the western flank of the Cumbre Vieja ridge, and was built up by a mainly strombolian eruption from 19th September to 13th December 2021. The first erupted, clinopyroxene-amphibole-phyric tephrite lavas, are more evolved in composition than the subsequent clinopyroxene-olivine-phyric basanite flows, in a pattern resembling those described from the two former eruptions in Cumbre Vieja: Teneguía (1971) and San Juan (1949). Furthermore, the detailed study of lava samples from the Tajogaite volcano reveals not only a drastic change in mineralogy, from amphibole-rich to olivine-rich lavas, but also the existence of complex textures and chemical zoning patterns including: 1) different olivine crystal populations, with and without disequilibrium textures (reverse zoning trends; reaction rims or coronae); 2) sodium-rich corroded clinopyroxene cores -with occasional titanite inclusions- overgrown by oscillatory zoned euhedral rims in equilibrium with groundmass; 3) a range of oxide mineral compositions from magnetite to chromite and spinel and, 4) the occurrence of early, nickel-bearing sulphides as inclusions in clinopyroxene. All these features record the interaction between ascending primitive mantle magmas and, at least, one shallow reservoir where differentiation had already taken place leading to iron, alkalis and water enrichment. This kind of interaction probably triggered the onset of the eruption, and could also be responsible for episodic phreatomagmatic activity pulses during the whole length of the volcanic process.   
Results of a GPS Zenith Total Delay data assimilation experiment over Italy
Authors: Federico Stefano , Torcasio Rosa Claudia , Realini Eugenio , Tagliaferro Giulio , Dietrich Stefano
Published: February 2023

The Mediterranean area is often struck by severe weather events and deep convective events because of the presence of the warm sea, the complex orography of the area, and the specific synoptic scale environment. This scenario is worsened by climate change because, as climate change is affecting many weather and climate extremes, and the frequency and intensity of heavy precipitation events have increased in most of the world.Over the past years, the use of Numerical Weather Prediction (NWP) models, along with an increasing availability of computing power, led to an improvement of the forecast accuracy. However, NWPs have well-known difficulties in capturing the physical processes at small spatial and temporal scales which are involved in convective or severe weather events. In this work we study the impact of assimilating GPS-ZTD (Global Positioning System-Zenith Total Delay) on the precipitation forecast over Italy for the month of October 2019, characterized by several moderate to intense precipitation events. The Weather Research and Forecasting (WRF, version 4.1.3) is used with its 3DVar data assimilation system. The horizontal resolution is 3km while the vertical domain spans the whole troposphere and lower stratosphere.A dense network of about 500 GPS receivers was used for data assimilation and verification of the atmospheric water content. The dataset was built collecting data from all the major national and regional GNSS permanent networks, achieving dense coverage over the whole area.Results show that WRF underestimates the atmospheric water content for the period, and GPS-ZTD data assimilation reduced this underestimation by increasing the water content of the atmosphere. The GPS-ZTD data assimilation increases the precipitation forecast amount, and the model performance are improved up to 6h.Results for a case study show that the GPS-ZTD data assimilation can improve the precipitation forecast in different ways: predicting rainfall missed by the model without data assimilation or better focusing the precipitation already predicted by the model without GPS-ZTD data assimilation on the impacted area, the main drawback being the prediction of false alarms. 
Difference in the fate of surface and subsurface microplastics: an example for open and coastal waters
Authors: Pakhomova Svetlana , Zhdanov Igor , Berezina Anfisa , Yakushev Evgeny
Published: February 2023

Plastic is recognized as a threat to marine ecosystems and estimating the level of plastic and microplastics (MP) pollution of the World Ocean is nowadays the goal of many studies. However, the use of different methods for sampling and analysis of MPs leads to the problem of comparing the results obtained. Studies on surface MP pollution of the surface sea water are based on the application of the manta or neuston nets that collect water from the upper 10-20 cm layer (the “surface” MP) or submersible pumping systems, that collect water from the water layer 3-5 m below the sea surface (the “subsurface” MP). These two techniques allow to collect particles of different size fraction, i.e. >300 µm for the surface MP and >100 µm for subsurface MP. The aim of this work was to study the distribution of surface and subsurface MPs and to reveal an influence of oceanographic conditions on their spatial distribution as an example of the open ocean waters of the Central Atlantic and coastal water in Norwegian fjords. It was shown that microplastics found in the surface and subsurface layers differ not only in the size of the items found, but also in morphology, types of polymers, abundance, weight concentration and their spatial distribution. Different hydrodynamic processes affect the fate of plastic occurring exactly at the sea surface and several meters deeper. MPs inhabiting the subsurface waters (about 3-5 m depth) have buoyancy close to neutral and appear to be suspended in the surface mixed layer and are readily transported from the sources to the distant regions by ocean currents. Subsurface turbulence is probably the main process that maintains the MPs in the near-surface part of the water column. In contrast, the surface MPs (which are captured by sampling with surface nets) have positive buoyancy and its spatial distribution is significantly influenced by water dynamics, wind and waves, which led to a more scattered distribution on the ocean surface. It was shown that surface and subsurface microplastics differ significantly in a number of properties and, apparently, they should be considered as two independent groups that may have different sources, and their distribution is driven by different hydrophysical processes. Thus, MPs data collected using both methods simultaneously could provide additional information about MPs fate in the ocean.
Mapping and quantifying water fluxes at the land-sea interface using temperature, stable isotopes and pore water chemistry: An example from Königshafen, Sylt
Authors: Gilfedder Benjamin , Riedel Ramona , List Joana , Böttcher Michael E. , Frei Sven
Published: February 2023

Beach faces form the interface between terrestrial and marine systems. They act as a reactive zone between these two compartments, transporting and biogeochemically modifying chemical constituents such as nutrients, pollutants and carbon. Re-circulation of sea water through beach sediments is largely driven by tidal pumping and pressure gradients caused by tides, wave setup, and storm events that pile sea water up on the beach face. In contrast, terrestrial groundwater systems provide a source of low salinity and often nutrient rich water to the coastal zone. Mixing between these water sources is complicated by catchment morphology, variable density flow and very dynamic boundary conditions across temporal scales (e.g. tides, storms, yearly variations in terrestrial groundwater levels). Thus tracing water and nutrients fluxes through the subterranean estuary is not trivial. In this work we use a combination of point and long-term (7 months) temperature profile measurements and heat modelling to estimate water fluxes through the beach sediments into the Königshafen, on Sylt Island, Northern Germany. Temperature measurements were complemented by stable isotope and pore water chemistry measurements to infer the origin of discharge into the bay. The results showed that flow paths are complex, with dune morphology influencing the focal point for fresh groundwater discharge, with fluxes up to 20 cm d-1. Moreover it appears that either the islands fresh groundwater isotopic signature is either variable or at least two end-members contribute to the freshwater signature. Seaward, saline and brackish discharge occurs into the tidal creek draining the bay. Overall temperature measurements and heat modelling combined with pore water chemistry show potential to understand water and chemical exchange through the subterranean estuary and thus help to understand water and material fluxes at the terrestrial-ocean interface.
Estimating ocean dynamic sea level along the coast of the Netherlands using the regional ocean modelling system (ROMS) to seamlessly connect the observational period to projections for the 21st century.
Authors: Keizer Iris , Le Bars Dewi , Drijfhout Sybren
Published: February 2023

For sea-level projections along the coast of the Netherlands, ocean dynamic sea level (ODSL) is one of the most important contributors to sea-level rise in the 21st century. The ODSL output from the latest coupled model intercomparison projects (CMIP5 and CMIP6) is used for these projections. These CMIP models overwhelmingly use ocean models with a spatial resolution of 1° and a vertical z-level coordinate. Using these CMIP models for projections does not provide a seamless connection between observations and projections, this study aims to improve on that. To do so, we use a configuration of the Regional Ocean Modelling System (ROMS) for the North Sea with a resolution of 0.25° to downscale the spatial resolution of CMIP6 models and interpolate the vertical coordinate to topography-following sigma levels to improve the projections for the Netherlands.First, we use ROMS to reconstruct the ODSL along the coast of the Netherlands for the observational period. The regional model is forced using an atmospheric dataset constructed from ERA-interim and ERA-5 surface data and different ocean reanalysis datasets. It is not straightforward to compare the ODSL from different ocean reanalyses, as some datasets assimilate satellite altimetry data, whereas others do not. The ODSL from the reanalysis datasets that assimilate altimetry data are corrected for land ice and terrestrial water storage contributions to correct these differences.Then, we use ROMS to obtain new projections of ODSL for the coast of the Netherlands that seamlessly connect to the estimate of ODSL from ocean reanalysis data. We extend the forcing datasets for the regional ocean model of the observational period using the anomalies of CMIP6 variables. Using this new method, we obtain improved projections along the coast of the Netherlands.