bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of vein-sets and estimation of stress orientations and stress ratios from the Buxa dolomite, Main Boundary thrust (MBT) sheet, Siang Valley, Arunanchal Lesser Himalaya
Authors: Behera Swastik Suman , Bhattacharyya Kathakali
Published: March 2022

We estimate paleostress orientations (σ1, σ2 and σ3), stress ratios (φ) and driving pressure ratios (R′) from the extension veins exposed within the Buxa dolomite of the frontal Main Boundary thrust (MBT) sheet in the Siang valley, Arunanchal Lesser Himalaya. Based on the angular relationship with the bedding, the fractures and veins were divided into low-angle (<30°), moderate-angle (~30°-60°) and high-angle (>60°) sets. Observations in the field as well as at a microscopic level indicate that the high- and moderate-angle veins overprint the low-angle veins implying that the latter are the oldest. The high-angle veins are the most dominant set (~49%; mean orientation: ~23°, ~141°) followed by the moderate- (~31%; mean orientation: ~70°, ~176°) and the low-angle (~20%; mean orientation: ~58°, ~224°) set. The poles to the low- and high-angle veins define a clustered distribution in the stereoplot indicating that the pore fluid pressure (Pf) was less than the intermediate principal stress (σ2) during the formation of these vein sets. In contrast, the poles to the moderate-angle veins mark a girdled pattern in the stereoplot indicating that the pore fluid pressure (Pf) exceeded the intermediate principal stress (σ2) during their formation. On applying the stress inversion method (Yamaji et al., 2010) to the veins, 5 different generations of veins are revealed. Preliminary microstructural study indicates that the low-angle veins are dominantly quartz-rich, whereas the high-angle veins are dominantly calcite-rich indicating the presence of multiple generations of veins. The study also indicates the presence of blocky texture in the veins with the growth direction of the mineral grains at a high angle to the vein wall. Based on the stress ratio (φ), driving pressure ratio (R′) and the orientation of stress axes associated with each generation, the different generations of veins most likely formed under different stress conditions.
Metamorphic P-T-t paths of Neoarchean pelitic granulites from the Qingyuan terrane, eastern North China Craton
Authors: Liu Gang , Lu Jun-sheng , Kong Xu , Feng Qiang , Li Yu-ting , Zhang Yi-yi
Published: March 2022

Precambrian high-pressure (HP) granulites can provide crucial information for reconstructing ancient continental nuclei. Here we report the pelitic granulites from Qingyuan terrane, eastern North China Craton (NCC), which are archean supracrustal rocks occurred as enclaves in gneisses. Two samples from the pelitic granulites both record clockwise P-T paths involving prograde stage (M1), peak stage (M2) and post-peak stage (M3). Prograde stage is represented by biotite, plagioclase, quartz, rutile and ilmenite, preserved as mineral inclusions whthin garnet porphyroblasts, formed at P-T conditions of 8-9 kbar/670-700 ℃ constrained by mineral assemblages within garnet porphyroblasts and Ti-in-quartz geothermometer. The peak stage (M2) can be represented by the garnet cores, matrix rutile, kyanite, K-feldspar and the P-T conditions are constrained to be ~12 kbar/800-820 ℃ by the isopleths of XPy and XGrs from the core of garnet grains. The followed post-peak stage (M3) can be represented by matrix minerals assemblages including garnet, biotite, K-feldspar, sillimanite, ilmenite, quartz and plagioclase, revealing isothermal decompression process to ~9 kbar constrained by the isopleths of XPy and XGrs from inner rims of garnet grains. Monazite age dating suggests that the pelitic granulites possibly reached the peak metamorphic stage at ~2.47 Ga, slightly later than TTG magmatic events. The clockwise P-T paths including sequential isothermal decompression (ITD) segments recorded by the pelitic granulites may be caused by a subduction-collision event during the late Neoarchean in the eastern NCC.
Combining a global groundwater model ensemble with in-situ data for groundwater assessment in the Mediterranean region 
Authors: Ben-Salem Nahed , Reinecke Robert , P. Karatzas George , Rode Michael , Jomaa Seifeddine
Published: March 2022

Growing water demands in the Mediterranean region have increased groundwater exploitation, imposing urgent and efficient groundwater management. Sustainable management requires a proper understanding of groundwater status and accurate estimates of groundwater levels with less uncertainty. In this context, large-scale modelling has been shown to assess groundwater resources under changing conditions, especially in regions known for data scarcity. This study aims to quantify the steady-state groundwater levels at continental scales using a model ensemble and in-situ groundwater observations. To test the models' applicability and validity, we utilize one of the most monitored groundwater systems in the Mediterranean region, the Iberian Peninsula. Outputs of three global gradient-based groundwater models (Reinecke et al. (2019), de Graaf et al. (2017), and Fan et al. (2013)) were compared to observations from long-term groundwater monitoring network. The model ensemble showed reasonable performance in replicating the groundwater levels for shallow groundwater, but performance deteriorated with increased elevation.

In this study, we argue that we can develop continental scale groundwater maps for groundwater assessment by combining model results with in-situ data. Historical groundwater levels were used to test, train and validate the different combination methods. Here we present the outcomes and discuss the accuracy of the final product. We see this study as a benchmark approach of using multi-model ensemble and observations to deliver better groundwater steady-state conditions as a baseline for groundwater users and managers in the Mediterranean region.

This work was supported by the German Federal Ministry of Education and Research (BMBF, Germany, Grant 01DH19015) under the Project Sustain-COAST, co-funded by EU PRIMA 2018 programmes.
Degassing kinetics of high salinity geothermal fluids
Authors: Boeije Chris , Weinzierl Wolfgang , Zitha Pacelli , Pluymakers Anne
Published: March 2022

The formation of free gas bubbles (degassing) is a major issue during production of geothermal fluids. These often contain substantial amounts of dissolved gasses, such as CO2, CH4 and N2. Lower pressures in the region surrounding the production well can cause dissolved gas to come out of the solution. This can have detrimental effects on the production and generally on the operation, such as corrosion of the facilities or reduced water production as the gas limits the space where the water can flow. This study aims to improve the understanding of the conditions under which free gas nucleates, including determination of the bubble point pressure and temperature and the rate at which bubbles form during depressurization.

The focus of this study is on CO2 degassing from high salinity brines. We report a series of well-controlled depressurization experiments in a pressure cell that allows for visual monitoring of the degassing process. The cell is filled with brine saturated with dissolved CO2 at high pressure and temperature. The pressure within the cell can be reduced in a reproducible manner thus allowing for repeatable experiments. A high-speed camera paired with a uniform LED light source is used to record the degassing process. The pressure in the cell is monitored using a transducer synchronized with the camera. The resulting images were analysed using an in-house MATLAB code, which allows for determination of the bubble point pressure and rate of bubble formation. Experiments were performed at high pressure (up to 200 bar) and temperature (up to 200 °C) using a fixed CO2 concentration of 200 mmol/L (i.e. 8.8 g/L). Two saline brine solutions are used to assess the influence of the salt concentration on the bubble nucleation process: a low salinity (1 M NaCl) and a high salinity (1.5 M CaCl2 + 2 M NaCl) solution.

A model based on the geochemical software PHREEQC was also developed to predict the solubility of CO2 in high salinity geothermal brines. This model allows for simulating the degassing behaviour at the same conditions as those used in the experiments. From these simulations, the theoretical bubble point pressure and temperature can be estimated along with the rate of gas exsolution during a depressurization process. As there are several alternative equation-of-states for CO2 in solution with brines, a comparative matching of the depressurization experiments with individual formulations is presented.
Using complex networks to predict abrupt changes in oscillatory systems
Authors: Ehstand Noemie , Donner Reik V. , López Cristóbal , Hernández-García Emilio
Published: March 2022

Functional networks are powerful tools to study statistical interdependency structures in extended systems. They have been used to get insights into the structure and dynamics of complex systems in various areas of science. In particular, several studies have suggested the use of precursors based on percolation transitions in correlation networks to forecast El Niño events.

Our aim is to provide a better understanding of the potential of such percolation precursors for the prediction of episodic events in generic systems presenting chaotic oscillations. To this end, we study the behavior of the precursors in a spatially extended stochastic Vallis model, an asymmetric Lorenz-63 type model for the El Niño-Southern Oscillation (ENSO). Our results demonstrate the ability of the largest connected component of the network to anticipate abrupt changes associated with the system's oscillatory dynamics.

This research was conducted as part of the CAFE Innovative Training Network (http://www.cafes2se-itn.eu/) which has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 813844.
Local Tie Analysis at Fundamental Sites in the CONT17 Campaign
Authors: Herrera Pinzón Iván , Rothacher Markus
Published: March 2022

In this contribution we highlight the challenges of the combination of space geodetic techniques through local ties, during the rigorous estimation of geodetic parameters, for the realisation of a global Terrestrial Reference Frame (TRF). Local ties at geodetic fundamental sites play an important role in the determination of a TRF, providing the necessary links to connect the different geodetic techniques. Moreover, the growing demands on the accuracy and stability of the ITRF, have turned the analysis of the quality of these ties into a crucial element to achieve a highly consistent frame, providing additionally the opportunity to identify technique-specific systematic biases  when comparing the space geodetic results with local measurements.

To study the impact of the local ties at fundamental sites, we use the Very Long Baseline Interferometry (VLBI) observations collected during the CONT17 campaign, together with simultaneous Global Navigation Satellite System (GNSS) observations of a subset of the International GNSS Service (IGS) global network. To this end, our approach performs the rigorous estimation of all parameter types common to the two techniques, namely station coordinates, troposphere zenith delays and gradients, and the full set of five Earth Orientation Parameters (EOPs) and their rates, and we include their full variance-covariance information during the combination process. In the central step of this processing scheme, we realise the GNSS-VLBI combination via the "official" ITRF coordinate ties, using and evaluating different weighting schemes, to obtain a unique set of consistent parameters. Moreover, we study the impact of tropospheric ties between the collocated VLBI and GNSS stations, which are essential for the height estimates. Thus, based on the analysis of the station coordinate repeatabilities and the characteristics and behaviour of the EOPs, we discuss the impact of the accuracy and weighting of the local coordinate and troposphere ties on the estimation of the different geodetic parameters.
Integrated flood risk management prioritization in Indonesia
Authors: Hankin Barry , Ramirez Lorena , Wood Ian , Green Anthony , Quincieu Eric , Lauren Yoas , Lawless Mark
Published: March 2022

Indonesia has severe flood risk from multiple sources, with average annual loss due to flooding estimated to be 33 trillion IDR (US$2.3 billion). Impacts from severe flooding is significant and a growing concern in Indonesia. Since 2001, on average, flooding results in 260 deaths per year, 14,000 people injured, 1.5 million people impacted or evacuated, and over 283,000 houses flooded. The annual budget managed Indonesian Government for investment in flood management is in the order of 7 trillion IDR (about US $493 million).

Prioritisation of budget expenditure therefore requires understanding of a diverse range of factors, including understanding of available hazard data across multiple flood sources, the distribution of risk at the basin scale, and preferences for equitable distribution of budgets and schemes in the pipeline. In a process of capacity building and training with government technical departments, a range of approaches were demonstrated and applied to a test basin, Bengaman Solo, Java. This included identifying areas of high risk based on different hazards and receptors, using a range of metrics from people at risk to economics, and key services against which to compare proposed schemes. Spatio-economic information on planned investments were prepared in a long-term roadmap as part of the project. It also involved understanding residual risk when different spatial strategies are deployed, and a new National Integrated Risk Analytics (NIRA) tool developed for the Asian Development Bank allows users to introduce a range of mixed measures from nature-based-solutions to property-level-resilience, defences and flood early warning system.

Having explored the use of all these tools a prioritisation process was co-developed and made flexible such that assumptions could be iterated to bring in local knowledge, new data such as climate change sensitivity or subsidence. The outcome has been a process that incorporates the best available hazard and risk data nationally across different sources, supported by a range of steps for which on-line training modules are available.
Distribution of carbonate sediments in the Maverick Basin, Texas, during the Cretaceous Ocean Anoxic Event 2 
Authors: Robinson Alexandra Sarah , John Cedric , Dale Annabel , Hawie Nicolas
Published: March 2022

The Ocean Anoxic Event 2 occurred at the Cenomanian-Turonian boundary (95-93 Ma) and is one of the most well defined OAEs of the mid-Cretaceous. It is visible in geological history by mass accumulations of organic-rich fine-grained sediment and a globally recognized positive isotopic carbon excursion. However, during the OAE-2 in numerous locations a period of oxygenation is observed. One of these locations is the Maverick Basin, Tx, situated on the Cretaceous Comanche Platform and between the Cretaceous Western Interior Seaway and the Proto Gulf of Mexico. The sediments deposited in this area prior to the OAE-2 exhibit properties more typical of an OAE, whereas during the OAE-2 sediments exhibit more oxygenated conditions. The Cenomanian-Turonian sediments here are well studied with regards to organic matter, but less understanding regarding the accumulation of the carbonates during the OAE-2. These sediments are known as the Cretaceous Eagle Ford Group. The Eagle Ford Group contains both organic matter and carbonates. The presence of both carbonate and high total organic carbon (TOC) in the Eagle Ford Group requires a balance between organic matter accumulation and preservation and the production and accumulation of carbonate. This is because organic matter preservation requires primarily low oxygen conditions on the sea floor, by contrast carbonate production requires the presence of oxygen for calcifier organisms to thrive. This study will investigate the effect of the oxygen content within seawater on organic matter and carbonate production, accumulation, and preservation. This can then directly be correlated to locally understanding the oxygen conditions of Maverick Basin in relation to what is occurring locally prior, during and post the OAE-2. We chose the Maverick because of [a] the abundance of existing outcrops and subsurface data, and [b] because of the semi-isolated nature of the basin allowing us to test our hypothesis. Our hypothesis being that bottom water conditions in the Maverick Basin is driven by local eustatic changes and the primary control is local fluctuations in sea-level causing opening and closing of the connection with this basin and platform to the Tethys Ocean. We test this hypothesis by constructing forward stratigraphic models using the diffusion based DionisosFlow Forward Modelling Software. Our strategy is to use simplified scenarios in which we directly input ocean oxygen content based on the controlling factors of each scenario. By calibrating our model results against published present day total organic matter (TOC) maps of the Maverick Basin and published carbonate content from geochemical analysis, we can put forward an explanation for the proposed decoupling of the carbon cycle observed in the Eagle Ford Group.
Machine learning-based identification and classification of ocean eddies
Authors: Bolmer Eike , Abulaitijiang Adili , Kusche Jürgen , Fenoglio-Marc Luciana , Stolzenberger Sophie , Roscher Ribana
Published: March 2022

The automatic detection and tracking of mesoscale ocean eddies, the ‘weather of the ocean’, is a well-known task in oceanography. These eddies have horizontal scales from 10 km up to 100 km and above. They transport water mass, heat, nutrition, and carbon and have been identified as hot spots of biological activity. Monitoring eddies is therefore of interest among others to marine biologists and fishery. 
Recent advances in satellite-based observation for oceanography such as sea surface height (SSH) and sea surface temperature (SST) result in a large supply of different data products in which eddies are visible. In radar altimetry observations are acquired with repeat cycles between 10 and 35 days and cross-track spacing of a few 10 km to a few 100 km. Therefore, ocean eddies are clearly visible but typically covered by only one ground track. In addition, due to their motion, eddies are difficult to reconstruct, which makes creating detailed maps of the ocean with a high temporal resolution a challenge. In general, they are considered a perturbation, and their influence on altimetry data is difficult to determine, which is especially limiting for the determination of an accurate time-averaged dynamic topography of the ocean.
Due to their spatio-temporal dynamic behavior the identification and tracking are challenging. There is a number of methods that have been developed to identify and track eddies in gridded maps of sea surface height derived from multi-mission data sets. However, these procedures have shortcomings since the gridding process removes information that is valuable in achieving more accurate results.
Therefore, in the project EDDY carried out at the University of Bonn we intend to use ground track data from satellite altimetry and - as a long-term goal - additional remote sensing data such as SST, optical imagery, as well as statistical information from model outputs. The combination of the data will serve as a basis for a multi-modal deep learning algorithm. In detail, we will utilize transformers, a deep neural network architecture, that originates from the field of Natural Language Processing (NLP) and became popular in recent years in the field of computer vision. This method shows promising results in terms of understanding temporal and spatial information, which is essential in detecting and tracking highly dynamic eddies.
In this presentation, we introduce the deep neural network used in the EDDY project and show the results based on gridded data sets for the Gulf stream area for the period 2017 and first results of single-track eddy identification in the region.
The GEOframe Soil Plant Atmosphere Continuum Estimator (GEOSPACE) to investigate the vadose zone processes
Authors: D'Amato Concetta , Tubini Niccolò , Benettin Paolo , Rinaldo Andrea , Rigon Riccardo
Published: March 2022

This contribution illustrates the GEOframe Soil Plant Atmosphere Continuum Estimator (GEOSPACE). It is the ecohydrological model of the GEOframe system and it wants to simulate the soil-vegetation-atmosphere interactions to study and analyze the complex processes that occur in the Earth Critical Zone (CZ). The CZ is defined as the “heterogeneous, near surface environment in which complex interactions involving rock, soil, water, air, and living organism regulate the natural habitat and determine the availability of life-sustaining resources”.

GEOSPACE is a coupled model in which the three major components are WHETGEO, GEO-ET and BrokerGEO. WHETGEO, Water Heat and Transport in GEOframe, (Tubini N. and Rigon R., 2021), solves the conservative form of Richardson-Richards equation using the Newton-Casulli-Zanolli algorithm (Casulli V. and Zanolli P., 2010) that guarantees the convergence at any time step, and the proper transition from unsaturated condition to saturated one. Besides it deals seamlessly the surface water ponding. WHETGEO also implements the numerical solution shown in Casulli and Zanolli (2005) to solve the advection-dispersion equation and describe the solute transport. GEO-ET, EvapoTranspiration in GEOframe, computes evapotranspiration according to three different formulations, the Priestley-Taylor model, Penman FAO model and GEOframe-Prospero model (Bottazzi, 2020), by considering Jarvis model (Macfarlane et al., 2004) and Ball-Berry-Leuning model (Lin et al., 2015) to compute environmental and water stress factors. BrokerGEO is the coupler component that allow the exchange of data between the other two components in memory and considers the root water uptake for the computation of the actual evapotranspiration. The GEOSPACE model was tested with the lysimeter of the “Spike II” experiment (Nehemy et al., 2019; Benettin et al., 2021) of the Ecole Polytechnic Federal de Lausanne. The analysis we carried out with GEOSPACE concern the flux partitioning of precipitation and irrigation water into evaporation and transpiration; the soil water and groundwater storage; the transport of water stable isotopes through the soil. In this research we present them and show how GEOSPACE can be used to test hypotheses on the links between the plant water status and its isotopic signatures.

GEOSPACE is developed in Java using the Object-Oriented programming paradigm and it is completely open source, available on the GEOframe GitHub website. The code organization and its functionalities besides solving the hydrological issues are designed according to principle of open science to be inspectable and verified by third parties.
Styles of explosive activity during the 2021 Cumbra Vieja eruption, as illuminated by high-frequency imaging and acoustic sensing
Authors: Scarlato Piergiorgio , Taddeucci Jacopo , Andronico Daniele , Ricci Tullio , Civico Riccardo , Del Bello Elisabetta , Spina Laura , D'Auria Luca , Asensio-Ramos Maria , Calvo David , Pardrón Eleazar , Hernández Pedro , Pérez Nemesio
Published: March 2022

A variety of eruptive styles concurred to define the explosive activity of the 2021 Cumbre Vieja eruption (La Palma, Canary Islands, Spain). These styles include, as broadly defined, lava fountaining, Strombolian explosions, rapid Strombolian, spattering, ash-rich jets, and ash venting, and occurred both alternately and simultaneously at the multiple vents that hosted the activity during the more-than-three-months-long eruption. In order to capture the defining features and the underlying processes of these styles and of their transitions, we deployed FAMoUS (Fast, MUltiparametric Setup) during two field campaigns, between 22 September-1 October and between 5-9 November 2021. FAMoUS includes one high-speed camera (frame rate 250 to 500 frames per second (FPS) and 0.021-0.147 m/pixel resolution at the vent), one thermal camera (up to 50 FPS and 0.2-0.8 m/pixel .ca), three high-definition cameras (25 FPS, 0.03-1.2 m/pixel ca.), and one microphone (flat response between 0.5 and 10000 Hz, sampling rate 20 kHz). Preliminary video processing results, obtained using both manual tracking and Optical Flow routines, reveal ejection velocities of pyroclasts in the 20-220 m/s range, with the highest and the lowest values of peak velocity being recorded during Strombolian explosions and ash venting, respectively. All activity styles display ejection velocity fluctuations and variably marked ejection pulses, which are more pronounced during Strombolian explosions. Lava fountains feature the highest mean ejection velocity and a variety of fluctuation patterns, with larger-amplitude and more abrupt ones when transitioning towards Strombolian explosions. The maximum settling velocity of bomb-to lapilli-sized pyroclasts in the vicinity of the vent is remarkably stable around 50 m/s. The transition between the different styles of activity is marked by changing rates of ejection pulse frequency/amplitude and relative proportions of ash and bombs, pointing to a feedback between the volume, ascent rate, and frequency of gas pockets rising in the conduit, and the changes induced by their transit through the magma residing in the uppermost termination of the conduit.
Influence of riverine suspended sediment carbon content and particle size on turbidity
Authors: Sehgal Dhruv , Martinez-Carreras Núria , Hissler Christophe , Bense Victor , Hoitink Ton (A.J.F.)
Published: March 2022

In recent decades, optical backscatter techniques have increasingly become used to measure turbidity for the quantification of suspended sediment (SS) concentrations. One of the limitations of this method is that site-specific calibrations between SS concentration and turbidity (NTU) are needed. This is because turbidity (NTU) readings respond to factors other than SS concentrations, such as organic and mineral fractions, SS density, particle size distributions, and particle shape. Organic matter introduces irregularity in the shape of suspended particles that may aggregate to form flocs, which are not spherical, and different SS particle fractions (clay, silt, and sand) show different optical responses. Even though organic content is known to influence particle size and density and, as a result, turbidity, an explicit formulation of turbidity accounting for organic content is still missing. We conjecture that a better understanding of the relations between turbidity, SS carbon content (proxy for SS organic content under specific conditions) and particle size can help us to move from local calibrations towards ‘global’ dependencies. In this study, we investigate this by means of (i) a laboratory experiment, and (ii) in-situ high frequency SS characterization of carbon content and particle size. We collected sediments from 6 sites in Luxembourg representing different land use types and geological settings. The sampled sediments were wet sieved into 3 size classes and one part of the sieved samples were oxidized with hydrogen peroxide to investigate the effect of carbon content on turbidity and particle size. To this end, we first conducted laboratory experiments using a tailor-made setup consisting of a cylindrical tank (40-L) with an open top. A stirrer facilitated the homogeneous mixing of SS and prevented settling of heavy particles. Here, a submerged UV-VIS spectrolyser was used to estimate SS carbon content, a LISST-200X sensor to measure particle size distribution and a YSI EXO2 multi-parameter sensor to measure turbidity (NTU). Carbon content was measured in the laboratory with a CHNS Elemental analyser to calibrate the spectrometer readings, and a Mastersizer 3000 to measure particle size distribution. Laboratory results were then validated using field data from two instrumented sites in Luxembourg (Alzette River at Huncherange and Attert River at Useldange). Ongoing analysis will be discussed, and a global calibration equation between turbidity and SSC based on particle size, density and carbon content will be presented.
MYRIAD-EU: towards Disaster Risk Management pathways in multi-risk assessment
Authors: Ward Philip ,   MYRIAD-EU team
Published: March 2022

Whilst the last decades have seen a clear shift in emphasis from managing natural hazards to managing risk, the majority of natural hazard risk research still focuses on single hazards. Internationally, there are calls for more attention for multi-hazards and multi-risks. Within the EU-funded project MYRIAD-EU, we argue for an approach that addresses multi-hazard, multi-risk management through the lens of sustainability challenges that cut across sectors, regions, and hazards. In this approach, the starting point is a specific sustainability challenge, rather than an individual hazard or sector, and trade-offs and synergies are examined across sectors, regions, and hazards. We argue for in-depth case studies in which various approaches for multi-hazard and multi-risk management are co-developed and tested in practice. In this contribution, we present this project, whose goal is to enable stakeholders to develop forward-looking disaster risk management pathways that assess trade-offs and synergies of various strategies across sectors, hazards, and scales.
Seismic potential of the northern Chile region of the Nazca subduction zone
Authors: Michel Sylvain , Jolivet Romain , Rollins Chris , Jara Jorge
Published: March 2022

The northern Chile region of the Nazca subduction zone has hosted a Mw 8.5-9.0 earthquake in 1977 which induced a tsunami. The different magnitude estimates of this event are based on the evaluation of seismic intensities, tide gauge information and/or on the event’s inferred length, however, its actual along-strike extent is still under discussion. Based on geodetic data, former studies have also suggested this region awaits a Mw 8.6-8.8. In our study, we propose to revisit the evaluation of the seismic potential of the region, accounting for the fault’s moment deficit rate, earthquake magnitude-frequency distribution and earthquake physics. To do so, we combine an improved probabilistic estimate of moment deficit rate with results from dynamic models of the earthquake cycle, taking into account the influence of a potential barrier which could control the extent and therefore the magnitude of large events.
Extrapolation error quantification of the Arctic flux network across space and time, with data driven network optimization.
Authors: Pallandt Martijn , Jung Martin , Natali Susan , Rogers Brendan , Virkkala Anna , Watts Jennifer , Göckede Mathias
Published: March 2022

Unprecedented change is occurring in the Northern high latitude regions as a result of climate change. With related degradation of large carbon stocks sequestered in Arctic permafrost, it is essential that the carbon cycle, and its changes over time, is properly monitored. Greenhouse gas (GHG) fluxes can directly be monitored through the eddy covariance (EC) method and flux chambers. However, harsh weather conditions and remoteness make it difficult to establish and keep such monitoring sites running in the Arctic, and accordingly the past and current data coverage is comparatively sparse.

In this study, we aim to evaluate the coverage of the existing network of high latitude GHG flux monitoring sites, and quantify uncertainties in our understanding of regional-scale vertical carbon exchange processes. Our intent is to outline the limits of this network both spatially and temporally. We investigate how changes over time in flux observations affect the networks extrapolation potential, and how gaps in the network extent could best be filled. For this purpose, we applied and extended the network representativeness metric used for the FLUXCOM project. First we calculate an extrapolation index, which indicates the relative error when predicting fluxes at increasing dissimilarity in environmental conditions from the existing sites in the network. Here we train a model to predict fluxes based on the top 10 predictor variables from FLUXCOM of the nearest locations in variable space to reference flux data. We then correlate prediction errors to distance in variable space, which allows us to quantify prediction errors for each location and time step in our domain.

This analysis uses an extended version of our database of high latitude GHG flux monitoring sites produced in previous studies. This information is also available as an online mapping tool, which facilitates a variety of science applications. Although coverage is improved over past epochs, large gaps still remain in Russia and Canada, and across the Arctic wintertime. The most consistent year-round coverage of GHG fluxes occurs in Alaska and Europe. Our study prioritizes locations for network extension in Russia, Canada, and select locations in Alaska, and highlights where upgrades in instrumentation and battery capacity (e.g., extend monitoring into shoulder seasons and winter) would be most efficient.  
Planktic foraminifera seasonal calcification variations in the northwestern Mediterranean Sea
Authors: Béjard Thibauld M. , Rigual-Hernández Andrés S. , Sierro Francisco J. , Pérez-Tarruella Javier
Published: March 2022

Ocean Acidification (OA) is considered a major threat and is projected to impact all areas of global ocean, therefore understanding its ecological impacts remains a priority for science and management. The Mediterranean Sea is considered a highly vulnerable region, so we analyzed material coming from Planier sediment trap in order to characterize the seasonal variability of weight and calcification of planktic foraminifera. This sediment trap is located in the Gulf of Lions (GoL), in the northwestern part of the Mediterranean Sea, one of the few non-oligotrophic regions in the Mediterranean (high productivity period from January to May). We performed planktic foraminifera picking focusing on 3 different species: Globigerina bulloides, Neogloboquadrina incompta and Globorotalia truncatulinoides. A mean of 13 to 27 specimens per sample were picked. These foraminifera samples were then cleaned with the ultrasonication in methanol technique and then weighted using a Sartorius ME5 balance (precision= 0.001mg) in the micropaleontology laboratory of the University of Salamanca. A total of 126 samples and 2077 individuals were weighted. SBW (Sieve Based Weight) results showed that traditional used sieved size fractions do not provide enough control on the effect of morphometric parameters on the weight/calcification data, highlighting the need of a size-normalization. Area and diameter measurements were carried using a Nikon SMZ18 and a DS-Fi3 through the NIS Elements. MBW (Measured Based Weights) results showed that both of these parameters (area and diameter) have no influence on MBW values, indicating these values are good index for calcification intensity. Seasonal MBW variations differ according to the species: G.bulloides showed a maximum MBW values during the high productivity period, N.incompta reached its maximum values slightly after the high productivity period while G.truncatulinoides displayed a maximum calcification value during the low productivity period. Finally, we compared these results with “Optimum Growth Conditions” (Chlorophyll-a and species relative abundance) data.
Late Glacial paleoceanography in the outer Norske Trough, NE Greenland
Authors: Junna Tuomas , Pearce Christof , Hansen Katrine , Davies Joanna , Quirós Adrián , Seidenkrantz Marit-Solveig
Published: March 2022

The NE Greenland shelf, together with the Fram Strait, form the main sea ice and cold-water transport pathway between the Arctic Ocean and the Nordic seas. As such, these regions play a part in the Atlantic meridional overturning cell that is driven by the thermohaline convection taking place in subpolar and Polar regions. The ocean circulation, freshwater export and sea ice extent are heavily influenced by the interplay of oceanography, climate, glacial landforms and bathymetry.

Over the outer NE Greenland shelf, a layer of low salinity, cold Polar Water overlies a body of Atlantic Water (AW) that is either recirculated directly across the Fram Strait or further in the Arctic Ocean from where it returns as colder, modified Arctic-Atlantic Water. The relative contributions of these two types of AW recirculation bear significant implications to the deep-water formation and thus, the global ocean circulation, but little is known about the change in AW source over time and how it affects the local environmental settings.

This study aims to describe the paleoceanographic development of the outer Norske Trough using a multi-proxy approach to sediment gravity core DA17-NG-ST12-135G.  The core was taken on the NorthGreen17 Expedition from the outmost location in an east-west transect of cores along the trough. When combined with the other cores, it can be used to reconstruct the  oceanic forcing on the northeastern Greenland Ice Sheet  and its deglaciation history along the Norske Trough. The data used includes AMS 14C dating, sedimentary description, grain size analysis, µ-XRF core scanning and benthic foraminifera analysis. The preliminary results suggest intermittent early AW water influence and high seasonal productivity just east of the Northeast Greenland Ice Stream grounding line during the early deglaciation. AW influence on the outer NE Greenland Shelf is relatively constant after the deglaciation, but changes in productivity and current strengths are captured by the data.
Changes to the IFS atmospheric composition model in support to the CAMS update for CY48R1
Authors: Huijnen Vincent , Remy Samuel , Williams Jason E. , Chabrillat Simon , Guevara Marc , Kipling Zak , Flemming Johannes
Published: March 2022

The Copernicus Atmosphere Monitoring Service (CAMS) provides global analyses and forecasts of atmospheric composition, relying on the Integrated Forecasting System (IFS) of ECMWF.  The CAMS global model consists of the aerosol model of the IFS, IFS-AER, which is a sectional-bulk scheme, while the chemistry scheme is based on a CB05-based carbon-bond mechanism, with the option to couple this to BASCOE-based stratospheric chemistry.

The composition model is updated regularly, aligned with updates of ECMWF’s operational meteorological model. Here we report on updates planned for the next operational version, referred to as CY48R1. This concern revisions on a large range of topics, as developed over the recent years, and therefore impacting many aspects of chemistry and aerosol composition in troposphere and stratosphere. Main aspects concern:

Isoprene oxidation has been redefined, resulting in increased OH recycling and including a first model description of glyoxal as well as basic aromatics chemistry. 

NOy chemistry has been updated to include HONO and the longer-lived species CH3O2NO2.

A coupling with secondary organic aerosol formation has been established, and the coupling of secondary inorganic aerosol has been revisited.

the option to use the BASCOE-based stratospheric chemistry for operational application is actively considered.

Dry and wet deposition parameterizations have been revisited by including a GEOS-Chem based deposition parameterization using tile fraction specific deposition velocities. 

Aerosol dust emissions, and their optical properties have been revised.

The emissions handling has been updated, along with updates of the CAMS global emission inventories themselves.

The updates of the composition model and its emissions are tested in combination with updates to the tracer transport and data assimilation aspects, and the optimal configuration will be selected for operational application.

In this contribution we provide an overview of expected changes with emphasis on changes in composition modeling aspects. We will present the subsequent impacts on key atmospheric composition aspects, including air quality performance for major pollution regions across the world, aerosol optical depth, dust, and stratospheric composition products.  
Ace in the hole or a house of cards: Will a DeCK experiment help atmospheric chemistry?
Authors: Archibald Alexander , Collins William , Evans Mat , Griffiths Paul , O'Connor Fiona , Wild Oliver , Young Paul
Published: March 2022

 Over the past few decades the global atmospheric chemistry modelling community has collectively simulated 100000s of model years, producing petabytes of output, using increasingly complex  chemistry and aerosol schemes and higher resolution models. Yet, our understanding of key aspects of global atmospheric composition change has not evolved at the same pace as the tools we use to study it. Answers to key questions remain as uncertain now as they were two decades ago, including the strength of the methane self-feedback and the past and possible future evolution of tropospheric ozone in response to changing emissions and climate. Here, we will review the progress in understanding that has been generated in model intercomparison experiments (MIPs) from the last three IPCC assessment cycles: ACCENT (AR4), ACCMIP (AR5), and CCMI and AerChemMIP (AR6). We conclude that the aims and experimental design in these MIPs can be improved to reduce  the uncertainty in some of the outstanding questions in atmospheric chemistry. To this end  we propose a new set of experiments, specifically targeted at the atmospheric chemistry modelling community, that will go towards resolving outstanding challenges and integrate the wealth and expertise of chemistry transport and chemistry climate models. These experiments emulate the CMIP DeCK experiments and are designed to provide a continuing legacy for the community in understanding model evolution and process understanding. We aim to elicit  feedback and input into the experimental design from the community  with this presentation. 
Predicting spatial distribution of benthic foraminifera using Species distribution models
Authors: Abduljamiu Amao , Frontalini Fabrizio , Argadestya Ignatius , Kaminski Michael , Muller Pamela
Published: March 2022

In this study, we explore the use of Species Distribution Models (SDM) to infer spatial distribution of four species of benthic foraminifera around the globe. We modelled the distributions of Peneroplis planatus, P. pertusus, P. arietinus and Coscinospira hemprichii against a large collection of ecologically meaningful environmental variables (EMEV) variables in the Arabian Gulf. To identify combinations of effective predictor EMEV, we compiled several models and narrowed down to a subset based on set of predictive performance metrics. Mean iron concentration, diffusion attenuation, and dissolved oxygen were identified as important variables influencing the distribution of these species. The modelling task is essentially composed of two parts (1) Initial modelling of the actual known distributions of species in a well-defined basin and subsequent validation. (2) Spatial extrapolation over a global extent. Our model successfully predicted current habitat suitability for the four species within Arabian Gulf basin (AUROC = 92%).  It also identified areas along the western coastline as highly suitable habitats (Habitat Suitability Index > 0.8). Further, it reliably identified areas with known distributions of the four species (AUROC = 89%) around the world. Here we demonstrate how a SDM model can be a useful tool in capturing complex habitat features for benthic organisms and reduce sampling and accessibility concerns.
Local biaxial loading induced by end friction in uniaxial compression
Authors: Wang Hongyu , Dyskin Arcady , Pasternak Elena , Dight Phil
Published: March 2022

Rock samples tested in uniaxial compression tests are often observed to have spallation failure at the lateral surface of the sample caused by buckling of layers developing parallel to the direction of loading. These layers are caused by extensive crack growth. Yet, the experiments show that extensive crack growth in real 3D situations requires the presence of intermediate compressive principal stress (biaxial loading). We check the hypothesis that the intermediate principal stress is generated by the direct contact with metal loading platens, where the “frictional” boundary conditions are developed at the sample ends, creating non-uniform stress distributions near the sample ends. By the use of the finite element method (FEM), we analyse the stress distributions at the immediate lateral surface of the cylindrical sample in uniaxial compression in the polar coordinate system. It is found that near the ends the sample is actually biaxially loaded: the circumferential stress could be induced to play the role of the intermediate principal stress. The sizes of the zones and the maximum magnitude of the circumferential stress depend upon the friction coefficient and the Poisson’s ratio of the rock. The biaxial load ratio is defined by the ratio between the circumferential compressive stress and the axial stress. Comparing the biaxial load ratio determined in numerical models with the critical biaxial load ratio inducing extensive crack growth, the spallation of rock samples in uniaxial compression tests can be interpreted from a new perspective.
Cluster Analysis of Velocity Profiles around Hudson Bay using Unsupervised Machine Learning
Authors: Kharita Akash , Gilligan Amy
Published: March 2022

Understanding deep crustal structure can provide us with insights into tectonic processes and how they affect the geological record. Deep crustal structure can be studied using a variety of seismological techniques such as receiver function analysis, and surface and body wave tomography. Using models of crustal structure derived from these methods, it is possible to delineate tectonic boundaries and regions that have been affected by similar processes. However, often velocity models are grouped together in a somewhat subjective manner, potentially meaning that some geological insight may be missed. Cluster analysis, based on unsupervised machine learning, can be used to more objectively group together similar velocity profiles and, thus, put additional constraints on the deep crustal structure.

In this study, we apply hierarchical agglomerative clustering to the shear wave velocity profiles obtained by Gilligan et. al. (2016) from the joint inversion of receiver functions and surface wave dispersion data at 59 sites surrounding Hudson Bay. This location provides an ideal natural laboratory to study Precambrian tectonic processes, including the 1.8Ga Trans-Hudson Orogen. We use Ward linkage to define the distance between clusters, as this gives the most physically realistic results, and after testing the number of clusters from 2 to 10 find there are 5 main stable clusters of velocity models. We then compare our results with different inversion parameters, clustering schemes (K-means and GMM), results obtained for Vp (P-wave velocity) and ρ (Density), as well as results obtained for profiles from receiver functions in different azimuths and found that, overall, the clustering results are consistent.

The clusters that form correlate well with the surface geology, crustal thickness, regional tectonics and previous geophysical studies concentrated on specific regions. The profiles in the Archean domains (Rae, Hearne and Superior) were clearly distinguished from the profiles in the Proterozoic domains (Southern Baffin Island and Ungava Peninsula). Further, the crust of Melville Peninsula is found to be in the same cluster as the crust of western coast of Ungava Peninsula, suggesting similar crustal structure. Our study shows the promising use of unsupervised machine learning in interpreting deep crustal structure to gain new geological insights.