bluuebunny/crossref_metadata_2025 huggingface dataset:
Sources of material drift into the Ural foredeep at the beginning of collision (Southern Urals)
Authors: Volodina Ekaterina , Tevelev Alexander , Borisenko Alexandra , Koptev Egor , Shestakov Petr , Pravikova Natalia , Novikova Anastasia
Published: February 2023

Introduction. This work is devoted to the study of the sources of   drift material during the formation of Late Paleozoic deposits of the southern part of the Pre-Ural trough. Sample for the study was taken in a quarry near the Urgala region, Bashkortostan area. The section is represented by conglomerates with a sand matrix. These deposits belong to Ural forland basin. The age of this conglomerate formation – Moscovian (Middle Carboniferous).Materials and methods. The most reliable determination of sources is possible due to U-Pb zircon dating. We also analyzed some thin sections for detailed studying of sandstone composition.Results and discussion. Zircon grains vary greatly in shape and size. In some grains, the core and edges are clearly visible; others are full of inclusions, cracks, and zones of metamict decay. The size of the crystals varies from 60 to 400 microns. Most of the ages obtained fall in the interval from the Ordovician to the Devonian, less on the Lower and Middle Riphean. Single grains are of Cambrian, Vendian and Late Riphean age. Early Proterozoic and Archean grains are absent in the sample.The most difficult interval is from the Cambrian to the Devonian, it accounts for the majority of the ages (410-430 Ma). Within the studied territory, the volcanic rocks closest to the sampling site are located in Nyazepetrovsk and Bardym allochthons, as well as in the Tagil arc. In addition, Devonian granitoids are found within the Ufalei anticlinorium. The largest number of Precambrian dates falls on the Middle Riphean. The source of zircons during the middle Riphean could be the Mashak formation, whose age is 1350-1346 Ma, however, there are no grains with the age of the Mashak formation in the sample.A relatively large number of grains have the early Riphean age of 1650-1500 Ma, which correlates perfectly with the age of the Ai formation. However, almost all Riphean formations, including the Ai formation, contain zircons with the peak at 2050 Ma (the age of migmatization in the Taratash block),but  the studied sample contains no zircons of 2050 million years age or older. This means that the Taratash block and the surrounding Riphean formations were not exposed at that time.Also, the largest number of lithoclasts in the studied sandstones are represented by siliceous rocks. The similar rocks compose the Ordovician-Devonian section of the Mayaktau Allochthon, which is located closely to the sampling site. Also, the thickness Aziam  formation   increases towards Mayaktau Allochthon. In addition to the sources described above, there is jne more source – Asha series (Vendian), because there are quite a large number of Middle-Riphean dates in the sample, which are typical for the rocks of the Asha series.Financial support. The research has been funded by RFBR and CNF as a part of the research project № 19-55-26009 Czechia_a
Small-scale Lagrangian modelling of air bubbles and oil droplets under breaking waves
Authors: Nordam Tor , Mostaani Arsalan
Published: February 2023

Lagrangian transport modelling is commonly applied for marine environmental transport problems. When applied to problems on a timescale of days to weeks, such as marine oil spills, Lagrangian models are often forced with environmental data from operational models for atmosphere, waves and ocean currents. These models typically have a temporal resolution of around 1 hour. Effects that take place on shorter timescale, such as entrainment of oil droplets and air bubbles due to breaking waves, must therefore be parametereised.On short timescales, the random flight approach is clearly more realistic than a random walk, since the particles have a well-defined and realistic velocity, regardless of the length of the timestep, and since particles in real turbulence do not instantaneously change their direction by arbitrarily large amounts. A consequence of this is that in random flight, particles exhibit superdiffusion on short timescales, and normal diffusion on long timescales, compared to the de-correlation time of the turbulent motion. Random walk methods, on the other hand, always behave as diffusion. Hence, random flight methods are expected to be more relevant for small-scale modelling of transport on short timescale under breaking waves.Here, we consider small-scale modelling of oil droplet and air bubble entrainment, modelling the transport close to the surface, and at high temporal resolution. We use two different Lagrangian methods: random walk (AR0) and random flight (AR1), and compare the two modelling approaches to each other, as well as to pre-existing parameterisations of the average effects of entrainment. Input parameters to the Lagrangian models are informed by experimental turbulence measurements in a wave flume, and RANS-modelling of the breaking wave. Comparison of particle transport to observations in experimental flume work is ongoing.
On the hypothesis of microplastics resuspension by internal waves in a deep stratified lake.
Authors: Wells John C.
Published: February 2023

Kimitsuki et al (SIL 2022; EGU 2023, this session) have reported near-surface microplastic particle concentrations from 26 quasi-monthly sampling dates over three years in Lake Biwa, Japan.  The concentrations show a high degree of intermittency, both in the shallow South Basin and the deep North Basin.  Kimitsuki et al have suggested that the dates of high particle concentrations followed relatively strong wind events, which are hypothesized to stir up bottom sediments together with deposited microplastic particles. In the South Basin, which has an average depth of 4 m, this hypothesis seems very natural.  However the sampling point in the North Basin was located in waters well exceeding 60 m depth.  If the sampled microplastic particles there originated from wind-induced resuspension events, it seems likely that the resuspension occurred at shallower bottom depths close to shore.Through well-resolved hydrodynamic simulations, combined with particle tracking, the current work considers how resuspension at shallow depths, followed by advection during the days preceding sampling, might explain the two highest spikes in Kimitsuki et al’s sampled concentrations in the North Basin.  These spikes occurred on June 20, 2021 and July 4, 2021, when measured particle concentrations were respectively 54 and 46 particles/m3, as may be compared to the median value over the three-year campaign of 6.5 particles/m3.  Preceding both dates, both forward and time-reversed particle tracking suggest that the sampled microplastic particles could have been resuspended from the lakebed at depths of around 10 meters, near to the shore about 5 km northwest of the sampling point. At this location and depth, internal waves, associated with vertical undulations of the thermocline, were predicted to induce strong water currents near the lake bottom.  The simulated near-surface currents were then predicted to transport such resuspended particles offshore toward the sampling location.
Determining clock errors of ocean-bottom seismometers: an ambient-noise based method designed for large-scale ocean bottom deployments
Authors: Naranjo David , Parisi Laura , Jónsson Sigurjón , Jousset Philippe , Werthmüller Dieter , Weemstra Cornelis
Published: February 2023

The timing of the recordings of ocean-bottom seismometers (OBSs) is critical for accurate earthquake location and Earth model studies. GNSS signals, however, cannot reach OBSs deployed at the ocean bottom. This prevents their clocks from being synchronized with a known reference time. To overcome this, we developed OCloC, a Python package that uses time-lapse cross-correlations of ambient seismic noise to synchronize the recordings of large-scale OBS deployments. By simultaneously quantifying deviations from symmetry of a set of lapse cross-correlations, OCloC recovers the incurred clock errors by means of a least-squares inversion. In fact, because non-uniform noise illumination patterns also break the symmetry of (lapse) cross-correlations, we introduce a distance-based weighted least-squares inversion. This mitigates the adverse effect of the noise illumination on the recovered clock errors. Using noise recordings from the IMAGE project in Reykjanes, Iceland, we demonstrate that OCloC significantly reduces the time and effort needed to detect and correct timing errors in large-scale OBS deployments. In addition, our methodology allows one to evaluate potential timing errors at the time of OBS deployment. These might be caused by incorrect initial synchronization, or by rapidly changing temperature conditions while the OBS is sunk to the sea bottom. Our work advances the use of OBSs for earthquake studies and other applications.
The emergence of projected scaled patterns of extreme weather events over Europe
Authors: Ozturk Tugba , Canbaz Emine , Bilgin Başak , Matte Dominic , Kurnaz Mehmet Levent , Christensen Jens Hesselbjerg
Published: February 2023

This work investigates the scalability of wet and dry persisting condition patterns over the European domain with global warming levels. For this aim, we have used the EURO-CORDEX ensemble of regional climate projections at 0.11° grid-mesh for daily minimum and maximum temperature and precipitation to analyze future changes in extreme weather events addressing climate warming levels of 1°C, 2°C, and 3°C, respectively. A simple scaling with the annual mean global mean temperature change modeled by the driving GCM is applied. The annual minimum of daily minimum temperature (TNN) is found to increase more compared to the annual maximum of daily maximum temperature (TXX) at the end of the century. We also identify the emergence of the scaled patterns of minimum and maximum temperatures and wet and dry persisting conditions about certain extreme weather indices. The emergence of the scaled patterns of TNN occurs from around 2040, whereas TXX pattern is emerging around 2050. Individual GCM-RCM pairs tend to have stable spatial patterns since then for both indices. The ensemble mean patterns are emerging earlier than the individual models.
Investigating the Role of Weather Patterns in Crop Yield Variability and Predictability
Authors: Knight Chris , Khouakhi Abdou , Waine Toby
Published: February 2023

Climate change is causing disruptions in Earth's weather patterns, leading to an increase in the frequency and severity of extreme weather events such as droughts, floods, frost, and heatwaves. These events can impact food production and lead to challenges in meeting the food needs of a growing population. Previous research has documented the role of temperature and precipitation during the growing season in explaining crop yield variability. For example, droughts and extreme heat can reduce cereal production by 9-10%.Current crop yield models use only a few meteorological variables to represent weather conditions. However, weather patterns or weather regimes, (i.e., persistent, and recurrent flow patterns of the large-scale atmospheric circulation) can provide a more comprehensive view of weather conditions, and can be used to predict and characterise extreme weather events and explain crop yield variation.In this study, we first conducted a literature review to examine the links between extreme weather events, such as heat waves, and droughts with weather patterns and regimes. One of the main findings of that review was the need to define what extreme weather is in the context of agriculture. The new definition is based on studies that identified optimal and terminal weather conditions for winter wheat at specific phenological stages. Using this definition of extreme weather, we analyse historic yields in East Anglia, UK, forming statistically based relationships between low yield years with a set of classified weather patterns from the UK Met Office. We focused on the weather patterns frequency of occurrence and persistence with additional consideration given to potential microclimates as we compare the effects weather patterns have on a specific farm with a long-term data set to the effects of the larger region. Preliminary analyses shows that a small number of these weather patterns are associated with high impact weather events that cause yield limiting conditions or physical damage to the crop such as wind lodging.It is hoped that further research will lead to the development of a next-generation crop yield variation model taking into account the weather patterns, which can provide longer-term predictions of regional crop yield variability to help agri-businesses, crop insurers and farmers to facilitate decision making, respond effectively to regional and global crop production shocks and food price spikes, and develop adaptation strategies to reduce the potential impact of extreme weather events.
Maximizing Ecosystem Services through Grassland Restoration and Adaptive Management in Solar Parks
Authors: Blecha Mirjam , Obriejetan Michael , Stangl Rosemarie
Published: February 2023

Keywords: Renewable energy, photovoltaics (PV), ecological restoration, ecosystem services, management strategiesThe drive for renewable energy has resulted in a heightened focus on expanding sustainable energy systems, with solar PV playing a crucial role in this transition. While large-scale solar parks are met with controversy due to potential land-use conflicts and negative effects on the environment, they also present an opportunity for multifunctional land use. To address these concerns, an integrated research project in Austria was launched to develop strategies for integrating solar parks ecologically and maximizing ecosystem services through grassland restoration and adaptive management. Additional data and analysis will be used to improve the ecological integrity and biodiversity of solar parks and explore opportunities for combined agricultural use. By focusing on expanding renewable energy systems, solar PV in particular, and developing strategies for integrating them ecologically, we can address the global climate crisis and species extinction while also creating systems that are beneficial for both the environment and society in the long term.However, specific and local conditions of solar parks must be considered in implementation and management. A monitoring system was set up to continuously record data on vegetation, local climate, and soil conditions, including measurements of soil water content, solar radiation, vegetation height, and plant species. Preliminary results show distinct effects of panel areas on several environmental factors, with the greatest impact on radiation and air temperature, also impacting the species composition in the area beneath and between panels.
High resolution fault analysis of the Vestnesa Ridge: a highly complex deep water fluid flow system in the east Fram Strait
Authors: Cooke Frances , Plaza-Faverola Andreia , Buenz Stefan , Amrouch Khalid , King Rosalind , Koehl Jean-Baptiste
Published: February 2023

Processes such as oblique mid ocean ridge spreading, glacial isostatic adjustment and slope instability provide a highly complex spatial and temporal record of stress in the Fram Strait. The Vestnesa Ridge is a contourite drift bounded by two slow spreading mid ocean ridges located beside a formerly glaciated margin. The total state of stress is difficult to separate into individual components therefore our focus is to ascertain whether there is a stress transfer from the deep crust into the shallow overlying (~200m) sedimentary cover. We use high-resolution P-cable 3D seismic volumes together with 2D seismic, to map deeper faults connecting with near surface deformation. We perform high resolution mapping of the ridge by examining the dip and strike of each distinct fault system. We use a pre trained 3D model to predict faults within each 3D volume and automatically extract faults at multiple intervals to capture temporal stress changes. To minimize noise, the model identifies faults based on edge preserved smoothing for a selection of peak frequencies. In our results we observe fault linkage between parallel faults that may become favourable locations for transtensional and transpressional stress expected in the strike slip regime predicted in the west of the ridge. Our results show that the east of the ridge has a dominant NW-SE fault strike and a present day tensile stress regime while towards the west, the NW-SE assemblage becomes less prominent and multiple fault systems dominate increasing the complexity of the system. We present a high detail comprehensive structural analysis of 3 study sites across the shallow ridge sediments and use our results to investigate differences in the strike and dip between sites to explore the influence of sedimentary faults and ridge geomorphology on the spatial evolution of seafloor seepage at a deep Arctic oceanic basin.
Depositional environment of coal and amber during the PETM and ETM-2 hyperthermal events in northern highlatitudes (Canadian Arctic)
Authors: Lückge Andreas , Reinhardt Lutz , von Gosen Werner , Blumenberg Martin , Galloway Jennifer
Published: February 2023

High-latitude terrestrial records of Paleogene hyperthermal events can help to calibrate global climate models seeking a refined understanding of extreme warming events; however, such high-latitude records are rare. The Margaret Formation at Stenkul Fiord, southern Ellesmere Island, preserves a record of the early Eocene hyperthermal events. This late Paleocene to early Eocene sedimentary archive is composed of fluvially derived clastic sediments and amber-bearing coals. However, as the Eurekan deformation event caused major synsedimentary tectonic movement, resulting in substantial unconformities, the development of a reliable stratigraphic framework for Stenkul Fiord has proved challenging thus far. Field mapping and satellite image interpretation were used to identify unconformities and other tectonic structures in a section at Stenkul Fiord. In combination with a previously dated ash layer (U-Pb zircon age of 53.7 Ma, ID-TIMS) and biostratigraphic association (Graybullian, NALMA) of rare vertebrate fossils, both the PETM and ETM-2 hyperthermal events were identified. In addition, samples for new carbon isotope data of bulk coal, organic-rich sediments and ubiquitous occurring amber were collected. Using this refined stratigraphic framework the average sedimentation rates were calculated, and stratigraphic completeness of the section was evaluated. It was determined that the amount of clastic sediment deposited at Stenkul Fiord increased near the end stages of the PETM and ETM-2 hyperthermal events. This is interpreted as a response of the fluvial depositional system to an intensified hydrological cycle during the hyperthermals. This probably resulted also in discharge events, in which amber was enriched in layers due its lower density and thus their preferential mobilization and re-deposition during water flooding the swamp forest environment. Whereas amber in general shows less depleted isotope values compared to coals, this process may explain the larger offsets between the istopic composition of coals and ambers observed in some layers, respectively. This late Paleocene to early Eocene deposits at Stenkul Fiord offer further possibilities to study the effects of global warming events on terrestrial northern highlatitude depositional systems.
3D Tomography across the Balmuccia Peridotite, Ivrea Zone, Italy - Project DIVE, phase two
Authors: Pasiecznik Damian , Greenwood Andrew , Hetényi György , Bleibinhaus Florian
Published: February 2023

The Ivrea Verbano Zone (IVZ) is one of the most complete crust upper-mantle geological references in the world, an area that the Drilling the Ivrea-Verbano zone project (DIVE) aims to study. Associated with the IVZ, the Ivrea Geophysical Body (IGB) is of particular interest, as it is a structure beneath the IVZ characterized by high seismic velocities and a strong gravity anomaly. Recent studies across the IGB indicate that dense mantle rocks are located at depths as shallow as ca. 3 km. Several geological, geochemical and geophysical studies are planned, including the drilling of a 4 km deep borehole that will cross the crust–mantle transition zone, and provide, for the first time, geophysical in situ measurements of the IGB.In preparation for the drilling campaign, a seismic survey was performed in October 2020 in collaboration with GFZ Potsdam, Université de Lausanne, and Montanuniversität Leoben. In this study, we present results from a shallow seismic survey across the Blamuccia Peridotite, where the prospective drill site is planned. The survey was carried out with a fixed spread of 200 vertical geophones and 160 3C-sensors, spaced at 11 m along three sub-parallel lines 50-80 m apart. Vibroseis source points were at 22 m stations along a 2.2 km line utilizing a 12-140 Hz 10 s linear sweep with 3 s listening time.Through the application of 3D traveltime tomography, a shallow velocity model was obtained. The model shows a good correlation with the surface geology and can outline the east and west boundaries of the peridotite body; however, it is not deep enough to interpret its relationship with the mantle. Velocity analyses performed through the tomography process show that the peridotite body must have a P-wave velocity at least greater than 7.3 km/s, which is consistent with the high velocities measured in several laboratory studies from samples throughout the area.Seismic data show a lack of reflectors from the peridotite body, which could be interpreted in two ways: The peridotite body is attached to the mantle, or its structure is such that reflections from its boundaries cannot be detected by our seismic survey due to its limited aperture. However, a deep reflector was observed in some shot gathers, originating from a depth between 2-3 km from sea level. This corresponds well to the depth of the crust-mantle transition estimated from gravity and receiver function surveys. The shallow 3D velocity was used for the application of refraction statics and the development of a deeper velocity model to perform 3D pre-stack depth migration. Extreme topography, high P-wave velocities, and vertical geological structures present a challenge for the imaging process.
Refactorization of the EVP solver
Authors: Rasmussen Till A. S. , Poulsen Jacob W. , Ribergaard Mads H. , Rethmeier Stefan , Hunke Elizabeth C. , Craig Anthony P.
Published: February 2023

Earth system models (ESM) strive to describe more and more details. This is often accomplished with the use of more complex descriptions or higher resolution. The limitation of this approach is often the computer system at hand. In many cases, ESM’s are written with a focus on the physical system development and less on how to structure the code according to infrastructure on the computer. This presentation focuses on the sea ice dynamics, and particularly on the solver for the Elastic-Viscous-Plastic (EVP) equations. The EVP approach introduces artificial elastic waves that are iteratively dampened. Hundreds of iterations are necessary to reach a solution. In the traditional implementation, each iteration requires communication between the processors using MPI calls.An analysis of the existing solver’s performance was first carried out based on the sea ice model CICE. Three performance challenges were identified with the current implementation: Two challenges relate to the parallelization itself, namely 1) General imbalance issues due to the nature of the challenge and 2) MPI synchronization after each sub-cycling. The third issue relates to the data structures chosen and their corresponding memory access patterns. This study aim at removing all three limiting factors by adjusting the memory access patterns and by adjusting the parallelization approach so that we can avoid the costly MPI synchronization after each sub-cycle, which enables the use of parallel instructions, which are available in modern hardware. The adjusted implementation runs significantly faster.EVP is just one component out of many others in sea ice/ESM model (and other modelling systems). The refactoring includes a novel integration that shows how the EVP solver can be integrated into various model systems via the MPMD pattern and hence also runs on heterogeneous systems.
Antarctic RINGS to characterize the Antarctic Ice Sheet coastal zone and Antarctic contribution to the global sea-level rise
Authors: Matsuoka Kenichi , Cui Xiangbin , Ferraccioli Fausto , Forsberg Rene , Jordan Tom , McCormack Felicity , Moholdt Geir , Tinto Kirsty ,   Antarctic RINGS
Published: February 2023

Regions where the Antarctic Ice Sheet reaches the coast are fundamental to our understanding of the linkages between Antarctica and the global climate system. These coastal regions contain multiple potential tipping points for the Antarctic Ice Sheet in the ongoing 2oC warming world, which must be better understood to predict future sea-level rise. The Antarctic Ice Sheet constitutes the largest uncertainty source in future sea-level projections, and this uncertainty is mainly rooted in poorly known bed topography under the ice sheet. Bed topography matters the most in the coastal regions as it controls the stability of the ice sheet. Together with an overview of the current multidisciplinary understandings of the Antarctic coastal regions, we present ensemble analysis of published datasets to present data and knowledge gaps, and their regional distribution is discussed in the context of ice-sheet evolution and instability. Finally, we identify outstanding science priorities and discuss protocols of airborne surveys to develop a comprehensive dataset uniformly all-around Antarctica.
The new reality of the Mediterranean: accelerating impacts of climate change
Authors: Khodayar Pardo Samira , Pastor Paco , Valiente Jose Antonio , Paredes-Fortuny Laura , Benetó Pau
Published: February 2023

The Mediterranean basin is a hot spot for climate change warming up to 1.5 times faster than the rest of the world with the Mediterranean Sea warming three times more than the oceans (MedECC 2020). A consensus exists about the magnification of extreme phenomena in the area under climate change (IPCC 2021). In fact, several types of risks currently affect and will continue affecting the region severely, from more frequent extreme weather events such as heat waves, droughts, or floods, to increasing sea surface temperature and coastal erosion due to rising sea levels. The impacts affect the region's ecosystems, economic activities, and, ultimately, human health. In addition, the effects also spread like “cascades” that generate multiple impacts in all socioeconomic sectors. Current change and future scenarios consistently point to significant and increasing risks during the coming decades in most impact domains such as water and energy resources, ecosystems, agriculture and food, fishery, health, and human security.The impacts of climate change have accelerated on the Mediterranean coast of the Iberian Peninsula in the last decades. In this presentation, we will discuss this acceleration based on observations of the notorious and progressive rise in atmospheric and sea surface temperature and the generalized reduction of mean accumulated precipitation in the region. In this context, the magnification of extreme weather phenomena in the region will be described in detail focusing on the spatio-temporal evolution of terrestrial and marine heat waves, droughts as well as catastrophic extreme precipitation in the autumn period.
Climix—a flexible suite for the calculation of climate indices
Authors: Zimmermann Klaus , Bärring Lars , Löw Joakim , Nilsson Carolina
Published: February 2023

Climate indices have long been an important tool for the evaluation of climate impacts and are commonly used both in research and practical risk assessment. The term generally refers to advanced statistics derived from daily data, such as the longest spell of consecutive dry days in a year, or the maximal precipitation in a single day in a given month. Initially, these indices were calculated for station data, but with the advent and increased utility of global and regional climate models, they are now commonly calculated for gridded data. The increased spatial resolution, together with the increased length of simulations to hundreds of years, the increased use of ever-larger ensembles of climate simulations, and the interest in a wider selection of possible future climate scenarios renders some established, serial algorithms ineffective. This is compounded by the fact that modern computing architectures derive their growing power no longer from the speedup of single computing units, but rather from the integration of larger numbers of parallel computing units. To fully utilize this potential, it is not enough to implement a straightforward parallelization of existing algorithms. Rather, we need to rethink the computing task from the start in a parallel framework.Here, we present parallel algorithms implemented in the Python framework Climix, that have proven useful in the calculation of climate indices for a large ensemble of climate simulations that provide the basis for the user-oriented climate service of the Swedish Meteorological and Hydrological Institute.Climix is available as open-source software and allows the calculation of a large number of climate indices both from a command-line interface with good support for common HPC schedulers such as SLURM and via a flexible Python API.
Teaching groundwater flow modelling using cloud-hosted Jupyter notebooks and FloPy
Authors: Kremer Yannick
Published: February 2023

Numerical modelling of groundwater flow is a challenging subject for both educators and learners. It requires fundamental insight in hydrogeology, mathematics and computer science. In addition, students need to learn to work with software developed for experts, which is far less user-friendly than the software they are familiar with. Many students will need extensive support to install, use and manage the software. One of the key challenges of teaching software-intensive subjects is the risk of teaching the software rather than the subject. To properly prepare students for further study and their future career they need to understand the modelling process rather than interface of a particular software.

In this presentation we want to share our experience of using FloPy models in cloud-hosted (Google Colab) Jupyter notebooks for teaching groundwater flow modelling. FloPy is a Python library for constructing, running and post-processing MODFLOW groundwater flow models. Models are constructed by describing their properties using Python code. We use Jupyter notebooks to write, store and run the models. These notebooks provide a flexible environment, in which students can combine model code with documentation, results, notes and images. We use Google Colab which is a free service that hosts these notebooks online, so that students can work on the notebook using any computer with an internet connection.

Teaching the class using FloPy and Colab yields several benefits compared to the approaches we used before, where students installed software with a graphical user interface (GUI) on their personal computers. Moving to a cloud-based environment has removed several technical barriers. There is no need to install any software and students need only a basic computer and internet access, reducing barriers to entry. Both FloPy and Google Colab are freely available, allowing students to use them outside the classroom as well. Students initially struggle with using Python as most of them have no programming experience. To overcome this, we give a basic introduction to Python and frequent exercises for students to practice.

The combination of FloPy and Jupyter notebooks also offers benefits to learning. The approach is more transparent than GUI-based modelling tools. The entire model is defined within the notebook, providing students with a clear narrative describing each step of the modelling process. This allows students to develop a deeper understanding of the numerical modelling process. This promotes problem-solving and critical thinking. The cloud-hosted models can easily be shared, promoting cooperation between students and making it easier for the lecturer to help students diagnose and solve problems. In addition to groundwater flow modelling. this combination of tools allows students to develop valuable skills in programming and data analysis that are applicable to a wide range of geoscience careers.
Geomagnetic secular variations over the last 23 ka recorded in Lake Chala, eastern equatorial Africa
Authors: Di Chiara Anita , Maher Barbara A. , Karloukovski Vassil , Hounslow Mark , Blaauw Maarten , Van Daele Maarten , Verschuren Dirk
Published: February 2023

Documenting the Earth’s magnetic field variations through time is fundamental for several disciplines. However, current geomagnetic models heavily rely on datasets biased towards mid- and high northern latitudes, whereas data from Africa and surrounding oceans are particularly underrepresented. In this study, we present a new record of paleo-secular variations (PSV) in geomagnetic field inclinations during the last 23 ka from Lake Chala, situated at 3° S near Mt Kilimanjaro in eastern equatorial Africa. This deep groundwater-fed crater lake is characterized by a high sedimentation rate (ca. 1 cm/10 years) and a particularly well-constrained age model based on 210Pb and 14C dating; and rock magnetic analyses have demonstrated the magnetic stability of the sediments. The Chala dataset is linked to PSV records from Lake Malawi and Lake Victoria using a sequence slotting technique to generate a composite PSV record for East Africa. The Lake Chala PSV record not only represents an important contribution toward a better understanding of local and global features of the Earth’s magnetic field, but also expands the utility of paleomagnetism as a key tool for dating of, and cross-correlation between, lake-based paleoenvironmental records and archeological sites throughout eastern tropical Africa.
b-value variation through the seismic cycle: Revisiting Parkfield
Authors: Mirwald Aron , Gulia Laura , Wiemer Stefan
Published: February 2023

The Parkfield section of the San Andreas fault has a history of frequently occurring moderate (M~6) earthquakes with recurrence times ranging from 12 to 38 years. Since 1985, it has been extensively monitored as part of the experiment to predict the next moderate earthquake. Using the rich data resulting from the high-resolution monitoring, studies have revealed several interesting and consistent patterns of the frequency-magnitude distribution (FMD) of earthquakes, measured by the b-value of the Gutenberg-Richter law. The fault consists of patches of low b-values (b < 0.6) that correlate well with locked patches and with the areas that slipped in the 2004 M6 earthquake. High b-values (b > 1.3) were found to correlate with creeping section of the faults, and both observations support the hypothesis of an inverse relation between differential stress and b-values. Further, the b-value was found to increase during the aftershock periods of the 2004 earthquake, but so far, no gradual loading throughout the seismic cycle has been documented at Parkfield.Here we revisit the b-values along the Parkfield section 19 years after the last M6 event, with the objectives to monitor and better understand the evolution of b-values in space and time as the segment approaches the next rupture. Our aim is first to benchmark and enhance approaches to map and monitor transients, to optimize uncertainty quantification, robustness, and resolving power of our statistical methods. This is best targeted by creating synthetics catalogues with known properties and then benchmarking different methods for spatial mapping and time-series analysis of b-values. We specifically investigate the recently introduced b-positive estimator and convert observed b-values and activity rates to earthquake probabilities. In a second step, we analyse the observed patterns in a context of gradual fault loading and repeated moderate events, to derive insights into the underlying physical processes. Finally, our aim to set up a ‘b-value’ observatory that will continuously monitor the space-time evolution of b-values and earthquake probabilities.
Rock magnetism for investigating the firing temperature of ancient ceramic artifacts: The case of the Sada Nishizuka coffin, Japan
Authors: Tema Evdokia , Hatakeyama Tadahiro , Ferrara Enzo , Davit Patrizia , Matsumoto Naoko , Mitsumoto Jun
Published: February 2023

The Kofun Period is an important epoch of the Japanese protohistory, spanning from the early 3rd to the early 7th century AD. It takes its name from the large megalithic mound tombs, called kofuns (“ancient graves”), which characterize and define this period. Such monumental burial mounds comprised a central stone funeral chamber, inside which a wood, clay or stone coffin was positioned together with offerings to the dead, such as jewelry, ornaments, weapons and pottery. Kofuns are of great importance for better understanding the Japanese archaeology and the social evolution that took place during the Kofun period in Japan. At the same time, the study of the pottery style and the technology of the baked clay coffins offers information about the ancient ceramic technology and the evolution of the funeral practices over time. In this study, we use rock magnetic analysis to investigate the firing temperatures and production technology of a clay coffin excavated at the Sada Nishizuka archaeological site, in Okayama prefecture, Japan. Thermal demagnetization, magnetic susceptibility, thermomagnetic curves and hysteresis loops performed before and after laboratory heating at increasing temperatures were used to determine the ancient firing temperatures. The results showed that all samples, even if belonging to different fragments coming from different parts of the coffin, experienced important enhancement on their magnetic properties at temperatures around 300-400 oC. Such important changes suggest that the coffin was fired at relative low temperatures, which were not enough to cause complete magnetic mineralogy transformations. The magnetic results were further compared with independent data obtained from X-ray powder diffraction analysis (XRPD). The clay mineral pattern obtained from the XRPD data indicates firing temperatures around 400 °C, based on the presence of kaolinite, while in some samples clay minerals characterized by thermal stability up to higher temperatures were also observed. Such results suggest that the coffin, probably due to its large dimensions, has not experienced homogeneous heating during its production, and thermal equilibrium was reached at relatively low temperatures, much lower than those applied in the pottery production. Nevertheless, such firing was sufficient to harder the coffin and make it suitable for its use. This study aims to highlight the potential of magnetic analyses to investigate ancient baked clays and the importance of multidisciplinary archaeometric analysis to better understand our past.
Can selected forage species improve soil quality in subtropical smallholder farming  
Authors: Wickander Niklas , Jørgensen Marit , Dörsch Peter
Published: February 2023

Livestock is vital for food security and economy for a large part of the population in Ethiopia. The country has the highest livestock numbers in Africa, but cultivation of forage crops is still not very common. Most of the feed for the animals is derived from crop residues after harvest of arable crops, and during the dry season, the livestock roams freely and grazes on communal land. The intensive grazing causes a low return of nutrients to the soil, which leads to severe degradation of the soil quality. We are investigating how introduction of selected perennial forage species impacts microbial activity in the soil and if it potentially improves soil quality. We use four different forage species, the grasses Brachiaria hybrid Cayman and Panicum maximum, and the legumes Desmodium intortum and Stylosanthes guianensis, in a greenhouse experiment. The plants are grown in quartz sand inoculated with four degraded Ethiopian farm soils, two from the southern Sidama region and two from the northern Amhara region. The plants are grown in single stands and in two-species mixtures of B. hybrid Cayman and P. maximum, and B. hybrid Cayman and D. intortum, for 12 weeks. To assess potential plant effects on the soils, we will sample the soil at the end of the experiment and determine microbial biomass carbon, nitrogen and phosphorus, and the enzymatic activity of four enzymes involved in C, N and P acquisition. This will be compared to a time zero analysis of the soil to discern the impact the plants have on the soil microbial nutrient stoichiometry.
Subsoil management in agriculture and changes in organic matter stocks
Authors: Guigue Julien , Bauke Sara L , Seidel Sabine J , Athmann Miriam , Schmittmann Oliver , Kögel-Knabner Ingrid , Amelung Wulf
Published: February 2023

Global environmental changes are threatening the productivity of agroecosystems. Floods or droughts, together with long-term decline in soil organic matter stocks are pointing to the necessity of finding solutions for sustainable performance of agroecosystems.Deep soil horizons store significant amounts of water, soil organic carbon and nutrients, and thus subsoil management is being increasingly considered as an option to sustain crop productivity under unfavorable conditions.We used samples from several field experiments in Germany designed to investigate the potential benefits of deep ploughing together with deep placement of organic fertilizers on soil organic matter stocks. We recorded hyperspectral images of 1-metre soil cores in the Vis-NIR range and modelled the C distribution at a very high spatial resolution (53×53 μm²). Using approaches for GIS analyses, we quantified the changes in C and N stocks and we will present their spatial distribution resulting from the incorporation of different types of organic fertilizer (compost vs green manure) in subsoils. The organic matter stocks and C:N stoichiometry are both impacted by the agricultural management and the imaging technique allows us to distinguish between increased amount of organic matter in hotspots or in soil mineral matrice and to discuss the mechanisms controlling the observed changes.
Opportunistic sensing of precipitation using commercial microwave links: opportunities and challenges
Authors: Uijlenhoet Remko
Published: February 2023

Microwave links from cellular communication networks have been proposed as an opportunistic source of precipitation data more than two decades ago. The first scientific studies demonstrating the potential of this ground-based remote sensing technique, in particular for areas around the world were dedicated rainfall observation networks are sparse, were published some 15 years ago. Since then, a small but dedicated community of scientists and engineers working at universities, national meteorological services, consulting companies, mobile network operators and telecommunication equipment manufacturers has been making significant progress in turning this promise into a reality. In the meantime, numerous papers and reports have been published, conference presentations have been given and courses have been delivered. However, real-time access to high-resolution rainfall information from commercial microwave link networks over large continental areas is still a dream. How far have we come after 20 years of research and development? What does the future have in stall for the hydrological and meteorological communities? What should be done to turn this dream into a reality? This presentation will attempt to provide some preliminary answers to these questions.
Some forests like it cold
Authors: Hammerle Albin , Spielmann Felix , Scholz Katharina , Oberhuber Walter , Wohlfahrt Georg
Published: February 2023

Forests cover roughly one third of the global land area and currently remove around one quarter of anthropogenic CO2 emissions, thus slowing down the increase in atmospheric CO2 concentrations. Forests account for approximately 90% of all terrestrial biomass, which corresponds to about 400 Gt C.However, the ratio of carbon uptake to release is a very fragile one and is determined by many factors such as water and nutrient availability, the amount and quality of light or stand age. In addition to the factors mentioned above, temperature is one of the most important factors that determine this ratio. Both fluxes determining the net ecosystem exchange (NEE), the gross uptake of CO2 by photosynthesis (GPP) and ecosystem respiration (Reco) are sensitive to temperature. Thus, we investigated the temperature sensitivity of NEE at a newly established pine forest field site in Austria at 960 m a.s.l. Applying an understory and an ecosystem scale eddy covariance system we were able to disentangle temperature effects on understory and tree crown CO2 exchange.We found a clear temperature optimum for CO2 uptake on ecosystem scale at around 20°C and a decrease in uptake on higher temperatures. This decrease was caused by (i) the understory turning from a slight sink for CO2 into a source of CO2 at higher temperatures, and (ii) a reduction of CO2 uptake in the tree canopy layer. Furthermore, we compared carbon flux data with continuous tree growth data from dendrometer measurements.
Rock Properties of Shallow Martian Subsurface with the RIMFAX Ground Penetrating Radar
Authors: Casademont Titus M. , Eide Sigurd , Shoemaker Emileigh , Berger Tor , Russell Patrick , Hamran Svein-Erik
Published: February 2023

The RIMFAX ground penetrating radar instrument on board the Mars 2020 Perseverance Rover has been continuously sounding the subsurface alongthe Rover traverse. In the data of the first 379 mission days on the Jezero Crater Floor we are able to identify hyperbolic patterns, likely caused by buried scatterers such as boulders or cavities in the upper 5 m of the subsurface. We present the first detailed estimates of radar wave propagation velocity by matching theoretical traveltime hyperbolas to the patterns generated by scatterers. The average dielectric permittivities are derived from these velocities and, consequently, the bulk rock densities for material above the scattering source. Simultaneously, we investigate the surface reflectivity to retrieve permittivity and density of the uppermost centimeter. Finally, we assess the radar attenuation by a constant-Q approach.The results are consistent with a solid rock, mafic interpretation of the Jezero Crater subsurface. The talk is based on the respective two most recent publications as well as work in progress.