bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Temperature Inference from Fixed Bias Langmuir Probes Set-Ups in Ionospheric Conditions
Authors: Enengl Florine , Marholm Sigvald , Adhikari Sayan , Marchand Richard , Miloch Wojciech J.
Published: February 2023

In this work, we show the first achievement of inferring the electron temperature in ionospheric conditions from synthetic data using fixed-bias Langmuir probes operating in the electron saturation region. This was done using machine learning, as well as by altering the probe geometry. The electron temperature is inferred at the same rate as the currents are sampled by the probes. For inferring the electron temperature along with the electron density and the floating potential, a minimum number of three probes is required. Furthermore does one probe geometry need to be distinct from the other two, since otherwise the probe setup may be insensitive to temperature. This can be achieved by having either one shorter probe or a probe of a different geometry, e.g. two longer and a shorter cylindrical probe or two cylindrical probes and a spherical probe. We use synthetic plasma parameter data and calculate the synthetic collected probe currents to train a neural network (using TensorFlow) and verify the results with a test set as well as with data from the International Reference Ionosphere (IRI) model. A table with computed currents collected by a spherical probe by Laframboise was extended to calculate currents of the synthetic plasma parameters for high eta values (eta >25) to cover a large altitude range (100-500 km, within Earth's ionosphere). The extrapolated values were benchmarked with Particle-in-Cell simulations. Finally, we evaluate the robustness and errors of different probe setups that can be used to infer the electron temperature. As the inferred temperatures are compared to results from the International Reference Ionosphere model, we verify the validity of the inferred temperature in altitudes ranging from about 100-500 km. We show that electron temperature inference from different combinations of spherical and cylindrical probes - three cylindrical probes, three spherical probes, four cylindrical and a spherical probe - can be achieved. Even minor changes in the probe sizing enable the temperature inference and result in root mean square relative errors (RMSRE) between inferred and ground truth data of under 3%. With further optimizations, the RMSRE can even be decreased to under 1%. When limiting the temperature inference to 120-450 km altitude an RMSRE of under 0.7% is achieved for all probe setups. In future, the multi-needle Langmuir Probe (m-NLP) instrument dimensions can be adapted for higher temperature inference accuracy.
Estimation of Spatially and Temporally Varying Biogeochemical Parameters in a Global Ocean Model
Authors: Mamnun Nabir , Völker Christoph , Vrekoussis Mihalis , Nerger Lars
Published: February 2023

Ocean biogeochemical (BGC) models are, in addition to measurements, the primary tools for investigating ocean biogeochemistry, marine ecosystem functioning, and the global carbon cycle. These models contain a large number of not precisely known parameters and are highly uncertain regarding those parametrizations.  The values of these parameters depend on the physical and biogeochemical context, but in practice values derived from limited field measurements or laboratory experiments are used in the model keeping them constant in space and time. This study aims to estimate spatially and temporally varying parameters in a global ocean BGC model and to assess the effect of those estimated parameters on model fields and dynamics. Utilizing the BGC model Regulated Ecosystem Model 2 (REcoM2), we estimate ten selected BGC parameters with heterogeneity in parameter values both across space and over time using an ensemble data assimilation technique. We assimilate satellite ocean color and BGC-ARGO data using an ensemble Kalman filter provided by the Parallel Data Assimilation Framework (PDAF) to simultaneously estimate the BGC model states and parameters. We assess the improvement in the model predictions with space and time-dependent parameters in reference to the simulation with globally constant parameters against both assimilative and independent data. We quantify the spatiotemporal uncertainties regarding the parameter estimation and the prediction uncertainties induced by those parameters. We study the effect of estimated parameters on the biogeochemical fields and dynamics to get deeper insights into modeling processes and discuss insights from spatially and temporally varying parameters beyond parameter values.
Argo-based anthropogenic carbon concentration and inventory in the Labrador and Irminger Seas over 2011-202
Authors: Asselot Rémy , Carracedo Lidia I. , Thierry Virginie , Mercier Herlé , Velo Anton , Bajon Raphaël , Pérez Fiz F.
Published: February 2023

The ocean is a net sink for a quater of the carbon dioxide emitted to the atmosphere by human industrial activities and land-use change (Cant). The North Atlantic Ocean encompasses the highest ocean storage capacity of Cant per unit area. In particular, the Labrador and Irminger Seas are two basins storing a high amount of Cant due to the deep convection activity taking place there. The temporal evolution of Cant concentration in these two basins and their Cant inventories in the 0-1800 depth layer are estimated over the period 2011-2021. The Cant values are estimated from Argo floats equipped with oxygen sensors, predictive neural networks (ESPER_NN and CONTENT) and a carbon-based back-calculation method (φCOT method). On average, Cant inventories are similar in the two basins and amount to 75.3 and 75.6 mol/m2 in the Irminger and Labrador seas, respectively. Over the study period, Cant inventories increase in the two basins at a storage rate of 1.01±0.14 mol/m2/yr in the Irminger Sea and 0.94±0.2 mol/m2/yr in the Labrador Sea. The processes involved in Cant evolution in the two basins are then investigated.
Salt tectonics and its influence on the development of the Romanian Carpathians
Authors: Tamas Dan Mircea , Tamas Alexandra , Dohan Daria , Tocariu Ioana Silvia Mihaela , Schleder Zsolt , Krezsek Csaba , Urai Janos
Published: February 2023

Salt is present in many orogenic fold-and-thrust belts and it serves as an excellent décollement. This often leads to a localization of deformation (folds and thrusts) within the salt or to the development of salt diapirs. The Romanian Carpathians provide a natural laboratory for the study of salt tectonics in orogenic settings because of the mix of available data. The subsurface data was acquired mostly for hydrocarbon exploration and production but provides aid in the regional understanding of structural style, salt mines offer excellent exposures of cleaned walls and some amazing outcrops that can be used for taking samples and detailed measurements.
The layered rock salt exposed along the Carpathians strongly varies in impurity content, ranging from clean, almost 99% pure halite to salt rich in impurities ranging from micrometer to meter-scale fragments of various lithologies (sandstones, limestones, green schists, and volcanics). Studying these exposures and the difference in deformation and mechanical behavior of impure halite-dominated salt is of high importance when predicting the long-term evolution of underground storage caverns and nuclear waste repositories.
Here, we present how we combine classical fieldwork methods with UAV-based digital outcrop models, with microstructure and composition analysis to gain insights into the long-term deformation and properties of rock salt.
 
Acknowledgments: DMT acknowledges the financial support of UEFISCDI grant PN-III-P1-1.1-PD-2021-0165
Stochastic coastal flood risk modelling in the east coast of Africa
Authors: Benito Lazaro Irene , Aerts Jeroen C.J.H. , Ward Philip J. , Eilander Dirk , Muis Sanne
Published: February 2023

Extreme coastal flood events can have devastating impacts in densely populated and low-lying coastal areas, affecting societies, economies, and the environment. Flood risk assessments play a key role in reducing the potential impacts of these events. At global scale, coastal flood risk assessments allow determining the prime price definition of (re-)insurance companies, establishing of climate adaptation and risk reduction measures and understanding flood hazard and risk in data-scarce regions.Flood risk assessments at large to global scales, however, have generally been based on extreme sea levels estimated for specific return periods, combined with static flood modelling approaches. These traditional approaches are computationally efficient but at large scales they neglect the spatial patterns of flood events, leading to miss-estimation of the risk. Stochastic flood modelling approaches, instead, can become an alternative to capture the spatiotemporal dependency of events.In this study we analyse the added value of a stochastic coastal flood modelling approach over a traditional return period-based approach for 1000 years of synthetic tropical cyclone events in the east coast of Africa. Synthetic tropical cyclone events from the Synthetic Tropical cyclOne geneRation Model (STORM) combined with the Global Tide and Surge Model (GTSM) will be used to simulate water level timeseries. The Super Fast INundation of CoastS (SFINCS) hydrodynamic flood model together with an impact model will be used to derive the flood risk.
Nitrate retention and subsidy in oligotrophic mountain stream-lake networks
Authors: Grefe Imke , Wynn Peter , Mackay Eleanor , Barker Philip , Grant Helen , Pereira Gloria , Maberly Stephen , Surridge Benjamin
Published: February 2023

With human activity rapidly accelerating the global nitrogen cycle, aquatic environments are facing increasing eutrophication and ecosystem damage. Oligotrophic headwater streams are particularly susceptible to nutrient pollution, which is affecting biodiversity, ecosystem services and water quality. However, not much in known about biogeochemical nitrogen cycling in these remote environments. This research presents seasonal data for nitrate concentrations and stable isotope signatures from oligotrophic mountain stream-lake networks in the English Lake District, UK. While phosphate concentrations were frequently below detection limit, nitrate was present throughout the year with concentrations ranging from 0.01 to 0.49 mg N L-1. Dual isotope analysis of δ15N-NO3 and δ18O-NO3 identified atmospheric deposition as an important nutrient source to the ecosystem and provided information on the fate of nitrate moving through hydrologically connected stream-lake networks. Some mountain lakes removed up to 69% of nitrate delivered by the inflow stream, while others were substantial sources compared to upstream concentrations. This contrasting lake response was consistent throughout the year, with in-lake nitrate subsidy being observed in systems where concentrations in the inflow stream dropped below 0.25 mg N L-1. These findings suggest that dominant biogeochemical processes may be controlled by nutrient load, and ecosystem response could potentially change with increasing nutrient pollution.
The decay of Zostera marina, representative for beach wrack, at the micro-tidal southwestern Baltic Sea coast on the island of Poel in Germany
Authors: Schätzle Philipp-Konrad , Schubert Hendrik , Kesy Katharina , Bengtsson Mia , Koziorowska-Makuch Katarzyna , Kuliński Karol
Published: February 2023

Beach wrack is defined as any material washed ashore by wind and wave actions plays a vital part in coastal ecosystems: it fosters dune formation and prevents beach erosion at land, provides food and shelter to beach fauna, both in and off the water. Nevertheless, it is often seen as nuisance and therefore removed at recreational beaches. So far, no complex data has been retrieved regarding the decay of beach wrack when left at the beach and in the shallow water.To gain insight into the decomposition processes of beach wrack local seagrass of the species Zostera marina was chosen as prime example species and vital part of beach wrack at the southwestern German Baltic Sea coast at the island of Poel. In different seasonal experiments, seagrass was filled into white and black litterbags. In another experiment, seagrass in white litterbags was left in the shallow water until total disintegration of biomass. Sampling was conducted in regular intervals. The seasonal experiments were moved from water to land and land to water every week to mimic the movement between these interfaces in tidal seas for a period of six weeks. Constant exposure to the shallow water lasted for between 140 and 210 days. With every sampling, the biofilm was scratched off the decaying leaves of seagrass. The development of its microbial community as well as biomass loss were investigated. C/N-ratio was measured with the respective changes over time. The influence of abiotic parameters like light, salinity and temperature for the microbial community during the decay were then evaluated. In respect to decomposition processes at micro-tidal coasts, these studies provide an important insight into seagrass decay, at land and in the shallow water. Beach management processes at recreational beaches, and the possibilities of nutrient back-flow, need to be implemented into nature-compatible approaches. A corresponding system based on this research results can be promoted for leading to a balanced coexistence between man and nature.  
Ocean and atmospheric forcing of ice dynamic variability of west Antarctic Peninsula glaciers
Authors: Wallis Benjamin , Hogg Anna , van Wessem J. Melchior , Davison Benjamin , van den Broeke Michiel , Meredith Michael
Published: February 2023

In Antarctica changes to ice dynamics dominate the ice sheet’s contribution to rising sea-levels. The Antarctic Peninsula (AP), has undergone the greatest atmospheric warming of any southern hemisphere terrestrial area in the 20th century. Over the last three decades, the AP has experienced significant change; floating ice shelves have collapsed and retreated, and the loss of ice shelf buttressing strength has led to an acceleration in ice speed and dynamic thinning of the grounded ice. On the west coast warming ocean water at depth has been linked to glacier terminus retreat, acceleration, and grounding line retreat.In this study, we use feature tracking of Sentinel-1 synthetic aperture radar (SAR) imagery to measure ice speed of the Antarctic Peninsula’s west coast tidewater glaciers from 2014-2022 at 6-12 day temporal resolution.Our results show widespread patterns of increased summertime ice speed over a study area of 105 tidewater glaciers. We observe average seasonal speed variability of 12.4 ± 4.2 %, with maximum speed change of 22.3 ± 3.2 % on glaciers with the most pronounced seasonality. We also measure ice dynamic changes on inter-annual timescales on the west AP coast in this period. We study one example, Cadman Glacier, in detail, which has increased speed by 1025 ± 83 m/yr (41.6%) from October 2018 to November 2019. This increased flow speed has been maintained until at least May 2022 causing terminus retreat, increased ice discharge, and dynamic thinning of grounded ice by 20.3 ± 2.1 m/yr.We investigate forcing mechanisms which may cause the seasonal and long-term dynamic variability we observe using a regional climate model, ocean temperature reanalysis data and remote sensing observations of terminus position. We find that summertime speed increases may be explained by a combination of perennial firn aquifer modulated meltwater runoff and seasonal patterns of terminus position change, revealing that these glaciers can respond to forcings on seasonal timescales. For the longer-term speed change, we find that the large acceleration of Cadman glacier is coincident with a period of anomalously high ocean temperatures on the west AP shelf.
Hydrated komatiites as a source of water for TTG formation in the Archean
Authors: Hermann Jörg , Tamblyn Renée , Hasterok Derrick , Sossi Paulo , Pettke Thomas , Chatterjee Sukalpa
Published: February 2023

Water plays a crucial role in the formation of new crust on modern Earth. Today, new continental crust is created through arc magmatism by fluid-fluxed mantle melting above subduction zones. The aqueous fluid is derived from the breakdown of hydrous phases in subducted oceanic crust as a result of a delicate interplay between phase stability and the cold thermal conditions in the slab. Hydrated and subducted ultramafic (mantle) rocks play a key role in supplying the water needed for wet mantle melting and provide an important link between the Earth’s deep water cycle and formation of crust with an average andesitic composition.Archean felsic crust consists of the typical Tonalite-Trondhjemite-Granite (TTG) Series, which were likely produced from melting of altered basaltic precursors. Previous studies suggest that the water-present partial melting of metamorphosed basalt at temperatures of 750–950 °C is required to produce large volumes of partial melt with TTG compositions. However, the source of such water is unknown and exposed serpentinised mantle rocks likely played a negligible role in the early Earth’s water cycle.We propose that hydrated komatiites played a vital role in TTG genesis. Using petrology, mineral chemistry and phase equilibria modelling of representative komatiite samples, combined with analysis of a global geochemical dataset of komatiites and basaltic komatiites, we show that during metamorphism hydrated komatiites can release at least 6 wt. % mineral-bound water. The great majority of this water is released by breakdown of chlorite and tremolite at temperatures between 680 and 800 °C. As the temperatures of komatiite dehydration are above the wet basalt solidus, the released water can trigger voluminous partial melting of basalt to ultimately create TTG batholiths. This considerable hydration potential of komatiites is due to their high XMg, which stabilises hydrous minerals during oceanic alteration on the seafloor, but also extends the stability of Mg-rich chlorite to high temperatures. During prograde metamorphism, the XMg, CaO and Al2O3 content of the reactive rock composition determines the proportion of chlorite vs amphibole, and therefore the volume of water which can be transported to temperatures of > 750 °C. Therefore, we suggest that water released from dehydrating komatiites - regardless of the prograde P–T path (i.e., tectonic scenario) they experienced - provided the free water necessary to partially melt large volumes of basalts to form the prominent and expansive TTG suits in the Archean. Even though komatiites make up moderate portions of greenstone belts, they thus likely played a key role in early crustal formation and the Earths’ early water cycle.
How to create the highest manganese ore grade in the world? A geodynamic story in the Atlas of Morocco.
Authors: Dekoninck Augustin , Barbarand Jocelyn , Ruffet Gilles , Missenard Yves , Mattielli Nadine , Leprêtre Rémi , Mouttaqi Abdellah , Saddiqi Omar , Verhaert Michèle , Yans Johan
Published: February 2023

The Imini mining district (Morocco) hosts the largest manganese (Mn) ore deposits of North Africa (~120.000 T in 2016). The area is world recognized for hosting several epigenetic karst-type high-grade manganese deposits in a 10-15 meters thick Cenomanian-Turonian dolostone unit. These unconventional Mn oxide deposits occur along a belt of ~25-30 km in the southern foreland of the intraplate Atlasic belt of Morocco. This is due to two laterally extensive ore bodies of nearly pure pyrolusite-rich manganese ores (72-88 wt.% MnO2) and a third discontinuous medium-grade coronadite-rich Mn ore (40–48 wt.% MnO2)(Dekoninck et al., 2016a, b; Gutzmer et al., 2006). Our recent works allowed precise dating and geodynamic reconstructions of the ore deposit genesis. The ore depositions occurred during (i) late Cretaceous to late Paleocene (~ 92 Ma, ~ 78–82 Ma, ~ 65–67 Ma and ~58 Ma), (ii) late Eocene (c. 36 Ma), and (iii) early Burdigalian to early Serravalian probably in two pulses at c. 19–20 Ma and c. 13 Ma (Dekoninck et al., 2021, 2023). This multistage deposition coincides with three geodynamic events linked to the uplift of the Atlas. The late Cretaceous uplift of the Atlas created the required hydraulic head to sustain (1) fluid-rock interactions between O2-poor acidic ground waters and the Triassic series source, (2) migration of the metal-rich low-temperature hydrothermal fluid from the rock source and (3) overpressure fluid in the Imini depositional site. The vanishing of Triassic series above the Imini anticline forced these hydrothermal fluids to mix with oxygenated ground and alkaline waters resident in the karst system and precipitated the Mn oxides. The N70°-oriented Atlasic tectonic structure controls the orientation of these epigenetic karst-hosted Mn deposits. The late Eocene – Early/Middle Miocene uplifts generated additional supplies and/or in-situ remobilizations of the primary late Cretaceous medium-grade ore to form the high-grade pyrolusite-rich ore.References Dekoninck et al. 2023 (accepted). Mineralium Deposita. Dekoninck et al. 2016. Mineralium Deposita 51, 13-23. Dekoninck et al. 2016. in: Mineral Deposits of North Africa. Springer International Publishing, Cham, pp. 575–594. Dekoninck et al. 2021. Mineralium Deposita 59, 935–956. Gutzmer et al. 2006. Economic Geology 101, 385–405.
Determination of Tidal Datums and Tide Characterization and Prediction in Cyprus via the PYTHEAS National Tide Gauge Network
Authors: Nikolaidis Marios , Danezis Chris
Published: February 2023

Tide gauges remain the fundamental instrument for the determination of the absolute sea level and its variation over time. Following the establishment of the PYTHEAS national tide gauge network, which consists of five tide gauge stations located in strategic positions along the coastline of the government-controlled areas of the Republic of Cyprus, sea level observations were collected and analyzed. The main objective of this research is the determination, for the first time, of the most important tidal datums to support hydrographic surveying activities and promote critical environmental studies, such coastal erosion. Through the analysis of the data the following tidal datums were determined: Mean Sea Level (MSL), Mean Tide Level (MTL), Mean High Water (MHW), Mean Higher High Water (MHHW), Mean Low Water (MLW), Higher High Water (HHW) and Lower Low Water (LLW). These datums were estimated from sea level observations collected over the time span between January 2018 to April 2022. The dataset underwent through a complete quality control procedure, which was designed according to the latest international standards and included, among others, the influence of the tide gauge stability and the barometric pressure on the time series, and the detection and elimination of outliers. Furthermore, a thorough harmonic analysis was carried out, by means of the Harmonic Analysis Method of Least Squares (HAMELS), on the sea level observation dataset to highlight the effect periodic motions of the Earth, Sun and Moon have on local tide. In the context of this research, a total number of 68 tidal constituents were identified. Moreover, by using the Doodson X0 filter, the astronomical impact on the sea level was estimated by separating the astronomical influence component from the meteorological residuals. Data processing and analysis were carried out using custom in-house developed software. Finally, the estimated mathematical values of the tidal constituents, each of which describe a specific cosine curve, were utilized to calculate a tidal prediction up to December 2026.
Earth science teaching in Italy and Sustainable Development Goals (SDGs), how is going?
Authors: Gravina Teresita , Iannace Alessandro
Published: February 2023

In 2010 in Italy a major change in Upper secondary school guidelines have been implemented, and the topic "Natural Science" was strongly affected by this reform (MIUR, 2010). Thanks to the new guidelines Earth science topics were distributed along 5 years of curricula in some fields of study, while before the reform geology topics were studied only during one school year. The new guidelines promoted the use of an experimental and multidisciplinary approach in natural science teaching and outdoor activities. After this reform, Realdon et al (2016) investigated how teachers implemented the new Earth Sciences curriculum through the five teaching years by means of a survey. The aim of this research was to understand the implementation of the new guidelines after the end of the first cycle of studies. Realdon et al (2016) results showed that most of the teachers interviewed did not follow strictly the new guidelines, in fact, there was a tendency to follow old teaching habits and practices, and theoretical teaching was still prevailing as the scarce use of laboratory.In 2022 the eighth cycle of students completed their upper secondary school studies according to MIUR (2010) guidelines, for this reason, we decided to distribute a new survey to natural science teachers to study the state of the art of earth science topics in Italian upper secondary school. The aim of the survey is to understand how to support Italian natural science teachers in their didactical activities with reference to Earth Science topics. This research is needed due to the major change that happened in Italian upper secondary schools after the Covid emergency and the remote learning experience, and evaluate the actual possibility for upper secondary school teachers to work multidisciplinary on civic education, and in particular on Sustainable Development Goals (SDGs). In the survey we investigated the use of digital and online line tools to support earth science teaching, and if there are other types of didactical support needed by teachers. In this poster, we will present the first result of the survey, in particular, the needs expressed by Italian teachers and how they can be supported by Earth Science Faculties and the Italian ministry of education.MIUR , Indicazioni nazionali (D.M. n 211 del 7/10/2010) “Indicazioni nazionali riguardanti gli obiettivi specifici di apprendimento concernenti le attività e gli insegnamenti compresi nei piani degli studi previsti per i percorsi liceali”Realdon, G., Paris, E., & Invernizzi, M. C. (2016). Teaching Earth Sciences in Italian liceo high schools following the 2010 reform: a survey. Rendiconti Online Società Geologica Italiana, 40, 71-79. 
Acoustic signatures of slow and fast earthquake: insights from laboratory experiments on simulated fault gouge
Authors: Pignalberi Federico , Giorgetti Carolina , Tinti Elisa , Casas Nathalie , Marone Chris , Collettini Cristiano , Scuderi Marco Maria
Published: February 2023

In the last decades, it has been observed that faults can slip both by slow aseismic creep and seismic events (i.e., earthquakes). Between these two slip modes, a wide variety of fault slip behavior can be observed, including low-frequency earthquakes, slow slip events and tremors. This wide variety of slip modes can radiate seismic energy at different frequencies whose content may be linked to the physical mechanisms at play. In the laboratory, it is possible to reproduce the entire spectrum of fault slip modes by modulating the loading stiffness of the apparatus depending on the critical fault rheologic stiffness (i.e. k/kc). This technique allows us to study, under controlled laboratory conditions, the acoustic signature of different fault slip modes to infer the physical mechanisms at their origin. To shed light on the nucleation mechanisms and seek for reliable precursors to failure of different slip modes, we performed friction experiments on powders that differ for granulometry and grain shape (i.e., glass beads with a grainsize < 150 µm; and quartz powders MinUSil with an average grain size of 10.5 µm),  to simulate fault gouge.  The experiments were conducted in a double direct shear configuration, instrumented with an array of piezoelectric sensors to record continuously Acoustic Emissions (AEs) at high recording rate (~10MHz). The experiments are performed at a constant displacement rate of 10 µm/s and using a spring to reduce the apparatus stiffness k, to match the critical fault rheological stiffness (kc). Following this procedure we  obtain slow slip events (i.e., k = kc) and fast events (i.e. k<kc). The continuous recording of the AE (a proxy for seismicity) during the seismic cycle shows an increase in the acoustic energy release while approaching failure, which is related to changes in fault physical properties associated with grain sliding/fracturing. This behavior is reflected in a systematic variation of the b-value approaching failure.Through this work, we focus on the frequency content of AEs during the laboratory earthquakes to understand how different slip modes radiate acoustic energy. Indeed, we observe two orders of magnitude differences in frequencies associated with AEs in MinUSil and AEs in Glass Beads. The analysis of this frequency content can add important information on the deformation mechanism of fault gouge at the microscale and the size of the slip patch during laboratory earthquakes.
FD-VIEWS: A new operational global flash drought early-warning system based on evaporative stress forecasts
Authors: G. Miralles Diego , Gou Qiqi , Koppa Akash , E. Beck Hylke , Zhu Yonghua , Lü Haishen , Li Hao
Published: February 2023

Early warning of flash droughts is crucial to mitigate their adverse impacts on agriculture, ecosystems, and water resources. In recent years, advances in weather forecasting have been significant, paving the way for the development of reliable flash drought early-warning systems. Based on these recent developments, we present the operational, global-scale Flash Drought Viewer, Index, and Early Warning System (FD-VIEWS), which combines a deep learning hybrid version of the Global Land Evaporation Amsterdam Model (GLEAM, Koppa et al. 2022) with high-resolution ensemble meteorological forecasts from the Multi-Source Weather product (MSWX, Beck et al. 2022). Based on probabilistic forecasts of evaporative stress, FD-VIEWS diagnoses flash droughts using the Standardized Evaporation Stress Ratio (SESR) proposed by Christian et al. (2019) and further developed by Gou et al. (2022). The early-warning system predicts not only onset, continuation, and termination, but also estimates intensification rate and drought severity. FD-VIEWS is evaluated on its ability to predict flash droughts globally over a 10-day forecast horizon. The evaluation of FD-VIEWS reveals a high skill in predicting flash drought onset and termination; the onset forecast skill is higher in arid regions, whereas the termination forecast skill is higher in humid areas. Overall, FD-VIEWS shows potential in improving our understanding of flash drought predictability and its drivers, and enables more effective water management.––––––––––––––––––––––––––Beck, H. E., van Dijk, A. I., Larraondo, P. R., McVicar, T. R., Pan, M., Dutra, E., Miralles, D. G., 2022: MSWX: Global 3-Hourly 0.1° Bias-Corrected Meteorological Data Including Near-Real-Time Updates and Forecast Ensembles. Bulletin of the American Meteorological Society, 103 (3), E710-E732.Christian, J. I., Basara, J. B., Otkin, J. A., Hunt, E. D., Wakefield, R. A., Flanagan, P. X., Xiao, X., 2019: A Methodology for Flash Drought Identification: Application of Flash Drought Frequency across the United States. Journal of Hydrometeorology, 20 (5), 833-846.Gou, Q., Zhu, Y., Lü, H., Horton, R., Yu, X., Zhang, H., Wang, X., Su, J., Liu, E., Ding, Z., Wang, Z., Yuan, F., 2022: Application of an improved spatio-temporal identification method of flash droughts. Journal of Hydrology, 604, 127224.Koppa, A., Rains, D., Hulsman, P., Poyatos, R., Miralles, D. G., 2022: A deep learning-based hybrid model of global terrestrial evaporation. Nature Communications, 13 (1), 1912.
Hydrodynamics of the Mediterranean Cassidaigne submarine canyon from observations
Authors: Brun Lénaïg , Pairaud Ivane , Silva Jacinto Ricardo , Garreau Pierre , Dennielou Bernard
Published: February 2023

The more than 6000 submarine canyons worldwide constitute key oceanic morphologies incising continental slopes. They favor exchanges of organic matter, water masses, carbon, heat or pollutants between shallow and deep waters, driving ecosystems. They interact with the shelf and slope circulation generating local dynamics that have rarely been surveyed and observed.Observations of currents, temperature and turbidity along the Cassidaigne canyon, in the Gulf of Lions, northwestern Mediterranean Sea, were carried out to understand the specific circulation patterns in submarine canyons and their transitions. Two oceanographic cruises led in 2017 and 2019 gathered data from the outer shelf and canyon head at 100-400 m to the base of the continental slope at 1900 m depth.The Cassidaigne canyon is characterized by a steep and narrow morphology and is located in an active circulation area. Near the canyon head and on the shelf, the current is modulated by the stratification, the bottom morphology, the general circulation and the wind. Intermittent upwellings and consecutive relaxations lead to strong transient dynamics characterized by near inertial oscillations inside the canyon. The succession of upwellings induce a quasi-permanent residual up-canyon flow as observed in the narrow gorge area at 1700 m depth. Along-slope currents crossing the canyon during Northern Current intrusion events in the Gulf of Lions favor a temporary down-canyon circulation. Finally, turbidity currents were observed for the first time in connection with upwelling events, suggesting the triggering role of canyons’ internal hydrodynamics on shelf sedimentary processes.
Estimating the parameters of a flood forecasting model: with or without updating procedures?
Authors: Astagneau Paul C. , Bourgin François , Andréassian Vazken , Perrin Charles
Published: February 2023

When they are used for operational forecasting, hydrological models are almost always combined with some kind of updating procedures. Then a question arises: should the model parameters be calibrated with or without the updating procedures? Calibrating with the updating procedures often improves forecast efficiency, but it can also lead to parameter inconsistency and ultimately to a drop in performance in some cases.In this study, we evaluate the pros and cons of making the parameters of a flood forecasting model vary with lead times. We investigate the dependencies of the model parameters to the lead times and determine where and when this procedure significantly improves forecast quality. A modified version of the GR5H hydrological model is used on 229 French catchments where 10,652 events were selected. The model is run at the hourly time step and combined with a simple updating procedure to produce forecasts at four lead times. The model parameters were estimated from a large screening of the parameter space (3 million runs for each catchment). Results show that the parameters related to fast catchment processes are the most dependant on lead times, indicating the need for more specific parameter estimation methods when modelling catchments prone to flash floods.
Multistability in a Coupled Ocean-AtmosphereReduced Order Model: Non-linear TemperatureEquations
Authors: Hamilton Oisin , Demaeyer Jonathan , Vannitsem Stéphane , Crucifix Michel
Published: February 2023

Reduced order quasi-geostrophic ocean-atmosphere coupled models provide a platform that preserve key atmosphere behaviours, while still being simple enough to allow for analysis of the system dynamics. These models produce typical atmospheric dynamical features like atmospheric blocking and other low-frequency variability, while having a low number of degrees of freedom. For this reason, these models are well suited to investigating tipping points or bifurcations in the Earth's climate due to their simplified but insightful dynamics. In our present work we compare the dynamics of an ocean-atmosphere coupled model, previously implemented with linearised temperature equations (Vannitsem et al., 2015), but here we solve the equations including the non-linear Stefan-Boltzmann law in the radiative temperature term. When compared with the original version of the model with linearised temperature equations, the modified version of the model is found to produce multiple stable flows in the coupled ocean-atmosphere system. We find, for increasing atmospheric emissivity, there is an increase in the number of stable attractors, and these stable attractors present distinct flows in the ocean and atmosphere and distinct Lyapunov stability properties.Vannitsem, S., Demaeyer, J., De Cruz, L., & Ghil, M. (2015). Low-frequency variability and heat transport in a low-order nonlinear coupled ocean–atmosphere model. Physica D: Nonlinear Phenomena, 309, 71-85.
Petrographic and mineralogical studies of the formation of coronitic gabbros in the Ambatondrazaka region, central Madagascar
Authors: Rarivoarison Heninjara
Published: February 2023

The Cryogenian gabbros of the Ambatondrazaka region belong to the Imorona-Itsindro plutonic suite that originated from an upper mantle source after the eastward subduction of the Mozambican oceanic lithosphere beneath the Precambrian Malagasy basement from 0.8–0.7 Ga. These gabbros exhibit a particular coronitic texture where each corona consists of a core of forsteritic olivine surrounded by three successive rims. The first rim is formed by clinoenstatite, the second is formed by the clinoenstatite-diopside intergrowth with some exsolutions of pleonaste and pyrope garnet. However, the last is formed by symplectites of pargasite with exsolutions of pleonaste. Assuming that the temperature gradually decreases and that the pressure remains constant or also gradually decreases, the coronitic texture is the result of three successive stages of mineral reactions. In the first stage at rim one, the crystallization of clinoenstatites was favored by the diffusion of Fe2+ and Mg2+ from the forsteritic olivine being rich in Mg2+ while the supply of Si and Al comes from the surrounding labradorite. During the second stage in rim two, the formation of the clinoenstatite-diopside intergrowth follows the same crystallization process as that in rim one, but the calcium input from the surrounding labradorite favored the crystallization of diopside. Additionally, the supply of Mg and Fe from olivine and Al from labradorite resulted in the formation of pleonaste and pyrope garnet exsolutions. In the last stage at rim three, the formation of pleonaste exsolutions is identical as in stage two, while the supply of H2O favored the crystallization of pargasite symplectites. Overall, the coronitic texture is the result of a solid-state metamorphic reaction due to orogenic uplift related to the Pan-African Orogeny (0.58 – 0.51 Ga). The anhydrous phases of the reaction in the upper mantle formed the pyroxenes, spinels, and garnet in rims one and two, while the hydrous phase in the continental crust favored the formation of pargasites in rim three. 
Find the culprit
Authors: Crea Francesco , Alessandrello Chiara , Parello Francesco , Somma Roberta , Spoto Sebastiano Ettore
Published: February 2023

In Forensic Geology, Environmental Forensics is devoted to ascertaining contaminants in the soil/subsoil, surface waters, and groundwaters. In such cases, forensic geologists usually accomplish activities concerning geological, hydrogeological, geochemical, and geophysical research to individuate the source of the contaminant substance and discover if this latter depends on anthropogenic or natural origins.Preliminary chemical data on groundwaters from some areas of the Peloritani Mountains showed anomalous high contents of fluoride F-, a halogen element in the atmosphere, sea, fresh waters, and minerals. Natural sources of fluoride in the groundwaters are volcanic gas, the sea, and minerals. Fluoride is an essential component in around 300 minerals, among which the most diffused are fluorite and fluorapatite. A significant chemical feature of the ions of fluoride is that they have the same charge as the hydroxyl group OH- and present an ionic radius very similar to OH-. These chemical characteristics make it possible that F- may readily substitute the hydroxyl group in minerals such as micas, X2Y4-6Z8O20(OH,F)4.Most of the collected groundwaters in the present research were hosted in aquifers formed by Variscan high-grade metamorphic rocks provided with fracture permeability and in aquifers made up of Tertiary to Quaternary siliciclastic deposits with porosity permeability. These aquifers have a silicate composition and are rich in biotite. Among micas, biotite is the most diffused mafic mineral in the high-medium grade metamorphic rocks (augen gneiss, gneiss, mica schists) of the Peloritani Mountains. This mineral is also widespread in weathered monomineralic lithoclasts of siliciclastic deposits (Miocene, middle to upper Pleistocene, Holocene to Actual clastic deposits) deriving from dismantling the chain's metamorphic rocks.Previous studies on biotite from acid plutonic rocks of India demonstrated that fluoride contents might reach a concentration up to 7 wt%. Biotite mica may be likely responsible for the natural fluoride contamination of some of the studied groundwaters, in some cases also commercially exploited in the past.WHO suggests that the F- concentration in the drinking waters must range between 700 and 1500 µg/l depending on the different climatic zones. Concentrations over 1500 µg/l in Italian drinking waters are prohibited and dangerous for public health.The present research carried out in the Peloritani Mountains is devoted to: i) defining the actual geographical extent of the identified F- anomaly; ii) studying the water/rock interactions to ascertain if the leaching of F- from biotite mica, present in the high-grade metamorphic rocks and siliciclastic deposits, may be the natural phenomenon responsible for the ascertained fluoride contamination; iii) search for possible other causes of F- contamination as the salt wedge intrusion in the groundwaters of the coastal areas.
Using advanced geophysical data processing to improve low detection data in archaeological sites
Authors: Oliveira Rui Jorge , Caldeira Bento , Borges José Fernando , Bezzeghoud Mourad
Published: February 2023

Geophysical data with noise issues are quite common, resulting in low detection conditions. This prevents the ground content from being evaluated to determine the existence of structures buried in the ground in an archaeological site. Standard processing on ground-penetrating radar and magnetic data does not effectively eliminate or mitigate this effect. The use of advanced and customized data processing is a viable solution to the problem. This processing can be applied using mathematical transforms in conjunction with data decomposition techniques, allowing for easier and less computationally intensive data manipulation. The circular symmetry of the data is enabled by the 2D Fourier transform, making operations like filtering easier to implement. In the transformed domain, factoring techniques such as singular value decomposition can be used (SVD). After analyzing the decomposed signal, the components can be matched to the signal and noise. The 2D wavelet transform allows for data decomposition, with operations such as multiresolution SVD and multidirectional gradient calculation applied to each channel to select the most informative content from a dataset. The chain application of these operations allows for the improvement of geophysical data despite an apparent lack of information. Testing on field data obtained at Villa Romana de Pisões (Beja, Portugal) is an example of successful application. Advanced geophysical data processing operations can improve the data and should be used in conjunction with standard operations.Acknowledgment: The work was supported by the Portuguese Foundation for Science and Technology (FCT) project UIDB/04683/2020 - ICT (Institute of Earth Sciences).
Sensitivity of the mass conservation method to the regularisation scheme
Authors: Gillet-Chaulet Fabien , Jager Eliot , Morlighem Mathieu
Published: February 2023

While being one of the most important variables for predicting the future of the ice sheets, observations of ice thickness are only available along flight tracks, separated by a few to a few tens of kilometres. For many applications, these observations need to be interpolated on grids at a much higher resolution than the actual average spacing between tracks.The mass conservation method is an inverse method that combines the sparse ice thickness data with high resolution surface velocity observations to obtain a high-resolution map of ice thickness that conserves mass and minimizes the departure from observations.  As with any inverse method, the problem is ill-posed and requires some regularisation. The classical approach is to use a Tikhonov regularisation that penalizes the spatial derivatives of the ice thickness and therefore favours smooth solutions with implicit spatial correlation structures. In a Bayesian framework, regularization can be seen as an implicit assumption for the prior probability distribution of the inverted parameter. Other popular geostatistical interpolation algorithms, such as kriging, usually require to parameterize the spatial correlation of the interpolated field using standard correlation functions (e.g., gaussian, exponential, Matèrn).Here we replace the Tikhonov regularisation term in the mass conservation method  by a term that penalises the departure from a prior, where the error statistics are parametrized with the same standard correlation functions. This makes the regularisation independent from grid spacing and regularisation weights do not need to be adjusted. We present and discuss the sensitivity of the mass conservation method to the regularisation scheme using a suite of synthetic and “true” bed from deglaciated areas and show that prescribing the correct regularisation always provides the most accurate solution.
Spatial-temporal development of paleo-pockmarks on the Chatham Rise from 3D imaging with subbottom profiler data
Authors: Warnke Fynn , Pecher Ingo , Hillman Jess , Davy Bryan , Strachan Lorna
Published: February 2023

Seafloor depressions, sometimes known as pockmarks, are commonly observed features on the ocean floor. Their shape and size can range from small, circular indentations (10s m) up to large, often irregularly shaped depressions (several kms in diameter). The origin of pockmarks is often attributed to focused fluid or gas seepage at the seafloor, but their formation mechanisms (e.g., gas/fluid composition, timing, physical processes) remain ambiguous in many cases. On the Chatham Rise, offshore New Zealand’s South Island, seafloor depressions cover an area >50,000 km², and appear to be bathymetrically controlled. For this region, it has been hypothesized that episodic release of geological CO2 resulted in the recurring formation of pockmarks at glacial terminations. Seismo-acoustic surveys allow the investigation of potential fluid-flow pathways and buried paleo-pockmarks. High-resolution imaging of shallow subsurface features can be conducted using hull-mounted, parametric subbottom profilers that are available on most larger research vessels. Higher frequencies (>1 kHz) and narrow acoustic beams provide very high vertical resolution (decimetre range) and small lateral footprints capable of resolving smaller structures than using conventional seismic. A recent voyage in 2020 acquired an extensive grid of densely spaced (~25 m) 2D subbottom profiles over a dense pockmark field on the Chatham Rise.Here we present a novel approach to create a comprehensive pseudo-3D cube from high-resolution 2D echosounder profiles using a recently developed processing workflow. Based on this generated cube, we perform a preliminary analysis of seafloor pockmarks and paleo-pockmarks in the shallow subsurface up to 150 m below the seafloor. Our analysis includes insights into the recurrence of pockmark formation at different geological times and an assessment of morphological changes and varying spatial locations over time. Additionally, we investigate a potential polygonal fault network beneath the lowermost layer of paleo-pockmarks that might channel upward fluid migration in the area.