bluuebunny/crossref_metadata_2025 huggingface dataset:
Detecting the preparatory phase of induced earthquakes at The Geysers (California) using K-means clustering
Authors: Iaccarino Antonio Giovanni , Picozzi Matteo
Published: February 2023

The generation of strong earthquakes is a long-debated problem in seismology, and its importance is increased by the possible implications for earthquake forecasting. It is hypothesized that the earthquake generation processes are anticipated by several phenomena occurring within a nucleation region. These phenomena, also defined as preparatory processes, load stress on the fault leading it to reach a critical state. In this paper, we investigate the seismicity preceding 19 moderate (Mw≥3.5) earthquakes at The Geysers, Northern California, aiming to verify the existence of a preparatory phase before their occurrence. We apply an unsupervised K-means clustering technique to analyze time-series of physics-related features extracted from catalog information and estimated for events occurred before the mainshocks. Specifically, we study the temporal evolution of the b-value from the Gutenberg-Richter (b), the magnitude of completeness (Mc), the fractal dimension (Dc), the inter-event time (dt), and the moment rate (Mr). Our analysis shows the existence of a common preparatory phase for 11 events, plus other 5 events for which we can guess a preparatory phase but with different characteristics of previous ones, indicating different possible activation behavior. The duration of the preparatory process ranges between about 16 hours and 4 days. We find that the retrieved preparatory process involves a decrease of b, Mc, and Dc, and an increase of Mr, as found by many authors. Finally, we show a clear correlation between events showing a preparation phase and the location of injection’s wells, suggesting an important role of fluids in the preparatory process.
Degradation Risk Assessment methods: comparative analysis and typology
Authors: Selmi Lidia , Vandelli Vittoria , Coratza Paola
Published: February 2023

The susceptibility to deterioration of a geosite is known as degradation risk. Its assessment is fundamental to have an overview of the condition of a geosite and to schedule a correct monitoring plan in order to conserve the geoheritage relevance and re-establish stable conditions that were lost. The degradation risk assessment provides precious information for a correct protection of the geological heritage and its management, with attention to the effects of climate change. A periodic assessment of the degradation risk helps the researchers to understand the environmental and anthropogenic processes that act on a geosite and to monitor its possible changes across time.Due to the increase in geoconservation studies, several methods of assessment of geosites have been published since the 1990s. However, there is little literature about degradation risk in connection with geoheritage. Geoheritage degradation risk should be assessed in the first stages of any geoconservation strategy, even more when the aim is to tackle the effects of climate change already in action. Four main criteria to assess the degradation risk are usually considered: fragility, natural vulnerability, anthropic vulnerability and public use. However, the terminology is not univocal and same terms are used by the authors differently. Hence, a standard methodology that supports the recognition and prevention of threats affecting geosites is missing.In this work are summarised and analysed the papers published until now on degradation risk assessment and  are classified in different typologies. The aims of this study is to analyse how methods of degradation risk of geoheritage developed and to compare them, to shed light on terms and methods and helps future research consider using the best methodology to evaluate how their own work.
Statistical Properties of Hot Flow Anomalies around Mars
Authors: Wu Mingyu
Published: February 2023

Hot flow anomalies (HFAs) are not only a terrestrial, but also a solar-system-wide phenomenon that could cause strong perturbations of the planetary magnetosphere and ionosphere. Based on the observations of Mars Atmosphere and Volatile EvolutioN (MAVEN) upstream of the Martian bow shock from 2014 to 2020, we have investigated the statistical properties of HFAs around Mars in this study. Our observation results show that HFAs can distribute in a wide region from the dayside to the terminator region of Mars. On average, these HFAs can last 63 seconds and have a thickness of 28 local proton gyroradii. They are more prevalent when the ambient solar wind is denser and faster. HFAs occur most preferentially for IMF magnitude from 1-4 nT. Most of HFAs around Mars are formed during the interaction between tangential discontinues and the bow shock. Heavy ions originating from Mars do not appear to affect the formation of HFAs. Martian HFAs can lead to tens of times variations of solar wind dynamic pressure only in tens of seconds, which could strongly influence the heights of Martian ionopause and induced magnetosphere boundary.
How does the potential to sequester carbon via short rotation forestry vary with species?
Authors: Gatis Naomi , Galstaun Leslie , Luscombe David , Vanguelova Elena , Hill Timothy , Xenakis George , Wilkinson Matthew , Heard Matthew , Anderson Karen , Morrison James , Brazier Richard
Published: February 2023

Conversion of land to short rotation forestry (fast growing, densely planted trees, harvested within 15 years) has increased in recent years.  The wood produced is primarily used in short lived products (e.g. paper) or as biomass for renewable energy production, quickly returning carbon to the atmosphere. We ask, how much potential is there to sequester carbon via short rotation forestry and how does it differ between species when soil type and meteorological conditions are the same?We present preliminary results from a species field trial nearing maturity (planted in 2010), comparing soil carbon stocks (pre-planting to the present day); woody biomass; total and heterotrophic below-ground respiration; soil methane fluxes and leaf area index assessments between six commonly used short rotation forestry species (silver birch, common alder, sycamore, sweet chestnut, aspen and red alder). 
A framework for quantifying parametric ice sheet model uncertainty
Authors: Maddison James , Recinos Beatriz , Goldberg Daniel
Published: February 2023

Ice sheet models, calibrated using observational data, provide a means of projecting our current best state of the knowledge of the system state into the future, so as to obtain information about possible future behaviour. However it is important to be able to estimate the uncertainty associated with these projections. The problem of quantifying ice sheet parametric uncertainty is considered, focusing specifically on the problem of quantifying the posterior uncertainty in inferred basal sliding and rheology coefficients. These measures of uncertainty are projected forwards in time to obtain measures of uncertainty in future quantities of interest. Automated code generation and automated differentiation tools are utilised, leading to an extensible approach. The role of the observational error model in defining parametric uncertainty is considered.
A global tracer release experiment to help estimate OH tropospheric concentrations and benchmark chemistry-transport models
Authors: Thanwerdas Joel , Brunner Dominik , Henne Stephan
Published: February 2023

Despite the urgent need for reduction of greenhouse gas concentrations, their emissions remain at high levels worldwide. Atmospheric inverse modelling allows to quantify these emissions by leveraging observations of greenhouse gas mole fractions and chemistry-transport models. However, this technique largely relies on models with an imperfect representation of transport and chemical processes and the resulting errors propagate to emission estimates. Atmospheric scientists can improve their models by comparing simulated processes against available observational data.One efficient, although challenging, way of acquiring such validation data is to perform a tracer release experiment. It consists of releasing one or multiple decaying tracers into the atmosphere at one or multiple locations in the world, and then observe their time-evolving mixing ratios to understand transport pathways, mixing and decay rates. To the best of our knowledge, tracer release experiments have only been performed at local or regional scales to study transport processes, but never at the global scale. A global tracer release experiment could generate invaluable data against which to compare model outputs. However, modelers must be able to disentangle transport and chemical processes from the data, which requires that the experiment be carefully designed. Subject to this requirement being met, it could help to better quantify and even reduce 1) transport errors by investigating inter- and intra-hemispheric transport and 2) chemistry errors by constraining OH tropospheric concentrations. These data could also help to create a benchmarking methodology to highlight the strengths and weaknesses of the regional and global models that are currently used to quantify greenhouse gas emissions.Here, we present design considerations for such a global tracer release experiment based on simulations with the 3-D chemistry-transport model ICON-ART. Our first results indicate that releasing several hundred tons of two tracers with different lifetimes as pulses could be sufficient to obtain a good estimate of OH concentrations along the parcel trajectories. This method could be applied at different locations in order to sample a large part of the world and at different times, e.g., to account for seasonal variations in OH concentrations. However, we also show that many parameters influence the results and therefore we enumerate the benefits but also the limits of such an experiment.
Ultramafic mine waste - potential material for CO2 storage and metallic elements immobilization
Authors: Kierczak Jakub , Cieślik Błażej , Pietranik Anna , Łacińska Alicja , Bateman Keith
Published: February 2023

Carbon dioxide, which is a direct product of the combustion of fossil fuels is the main component that enhances the greenhouse effect on Earth. For years, solutions have been developed to reduce the carbon dioxide present in the atmosphere. One of the methods of CO2 reduction is the mineral carbonation of rocks and anthropogenic materials. As a result of the reaction of silicates with CO2, new carbonate minerals that are stable under surface conditions are formed. Ultramafic rocks are considered one of the best substrates for mineral carbonation with the experiments showing relatively high carbonation efficiency. This is because they contain abundant Mg-rich minerals (olivine, serpentine) that readily react with CO2-rich fluids to form Mg-carbonates and silica. However these rocks contain also high abundances of metallic elements, in particular Ni, Cr, and Co, that may be mobilized during the carbonation experiments. This presentation aims at the characterization of selected ultramafic mine waste, in terms of the metallic element content. The goal of our research is to answer the question of whether it is possible to simultaneously bind both CO2 and metallic elements using mineral carbonation experiments. We have chosen three types of ultramafic rocks for our study, two are from abandoned quarries and the third is a mine waste accompanying magnesite exploitation. Their chemical composition is characteristic of ultramafic rocks with high contents of silica and magnesia (both up to 40 wt %), with minor Fe2O3 and alumina (up to 10 and 3 wt % respectively). Metallic element content reaches values of up to 3,400 mg kg-1 for Cr, 2,500 mg kg-1 for Ni, and 125 mg kg-1 for Co. Two rocks represent partially serpentinized peridotites, whose main minerals are olivine and serpentine. The third rock is serpentinite, composed almost exclusively of serpentine group minerals. The minor phases in all the rocks are chlorite and spinel group minerals, with variable chemical compositions ranging from magnesiochromite through Cr-magnetite to magnetite. Peridotites contain amphiboles as minor components whereas carbonates (dolomite and magnesite) and sulfides (mainly Ni-Fe sulfides) were identified as accessory minerals in all the samples. The main Cr-bearing phases are the spinel group minerals, in the case of Ni these are serpentines and olivines, while Co is mainly concentrated in sulfides. Bulk chemical analyses of magnesite veins, naturally occurring in one of the quarries, revealed up to 250 mg kg-1 of Ni, and up to 3 and 5 mg kg-1 of Cr and Co, respectively. Although this indicates that magnesite has the potential to structurally incorporate Ni, further investigations are required to constrain the incorporation mechanism and the potential for the immobilization of Cr and Co in carbonate minerals.AcknowledgmentThe work is funded by the National Science Centre, research project No. 2021/43/B/ST10/01594.
The effects of the temperature increase on the rainfall regimes in north-central Italy
Authors: Luppichini Marco , Bini Monica , Giannecchini Roberto , Zanchetta Giovanni
Published: February 2023

In the last few years, several works have studied rainfall regime changes with the increase of temperature as a result of global warming. These changes, documented mainly in northern Europe, still need to be clarified in the Mediterranean area. Many studies have identified sometimes contradictory trends according to the type of data used, the methodology, and the daily or subdaily types of events. Therefore, an in-depth investigation of the Mediterranean area is required for the definition of more certain future scenarios.In this study, we examined a database with more than 1,000 raingauges and thermometers in northern and central Italy to analyze the rapid extreme precipitation events (EPEs) in relation to temperature. This large database covers a low rainfall accumulation period (RAP) that allowed us to study the relationship between temperature and rainfall and to distinguish rapid from long events related to rainfall intensity. The results show different relationships between rainfall and temperature regarding seasons, RAPs, rainfall intensity, and geographical factors. The high spatial density of the database made it possible to identify spatial clusters with homogenous characteristics influenced mainly by geographical factors. With an increase in temperature, the wet season is characterized by a general increase in rainfall with a higher surge for intense and fast events. Instead, the dry season shows a general rainfall decrease for less intense and longer events, but an increase in rapid and more intensive rainfall events. This outcome has further implications involving a future decrease in water availability and an increase of the EPEs, causing an extremization of the climate during the dry season for northern and central Italy.
Effects of the Assimilation of Relative Humidity Reproduced From T-PARCII and Himawari-8 Satellite Imagery Using Dynamical Initialization and Ocean Coupled Model: A Case Study of Typhoon Trami (2018)
Authors: Lee JaeDeok , Chang Eun-Chul , Ito Kosuke , Wu Chun-Chieh
Published: February 2023

This study investigated rapid intensification (RI, +30 kt in 24 h) and rapid weakening (RW, -20 kt in 24 h) for Typhoon Trami (2018) using the Weather Research and Forecasting V4.2 with the three-dimensional Price-Weller- Pinkel ocean model. As with the previous Typhoon Lan (2017) case study, the three-dimensional relative humidity field reproduced from Tropical Cyclones-Pacific Asian Research Campaign for the Improvement of Intensity Estimations/Forecasts dropsonde data and Himawari-8 satellite imagery was assimilated during every tropical cyclone dynamical initialization process. Specifically, dropsonde data obtained from two aircraft campaigns for Lan and Trami is used. Numerical results showed that compared to without this special data assimilation, Trami’s RI and RW simulations were better improved with this special data assimilation with respect to track and intensity forecasts. Around the RI period, vertical wind shear noticeably decreased and convective bursts (vertical velocity ≥ 3 m s-1 with 30 dBZ at 2 km height) significantly increased during the RI period. With these favorable ambient and storm inner-core environments, Trami quickly formed an eye structure. After RI and slow intensification periods, Trami eventually reached the Category 5 Saffir-Simpson hurricane scale. This maximum intensity was almost maintained until it had turned northwards. After that, as its translation speed significantly decreased, RW occurred with substantial upwelling. This upwelling caused a stable boundary layer and made significant asymmetry of surface heat fluxes and convective clouds. During this significant sea surface cooling period, deep convective cells were significantly suppressed in the eyewall area. As a result, Trami underwent RW during this period. To sum up, Trami’s RI may be associated with the reduction of negative dynamic forcing around the RI period, whereas Trami’s RW may be related to negative thermodynamic forcing by ocean cooling with a very slow translation speed during the RW period. More numerical results and detailed analyses of Trami’s RI and RW will be shown in the 2023 EGU General Assembly. Keywords: dropsonde data assimilation, tropical cyclone dynamical initialization, rapid intensification, rapid weakening, WRF atmosphere and ocean coupled model AcknowledgmentThis work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMI2022-00410. 
Study on physical and chemical characteristics and source of atmospheric Single particulate matter in Rizhao city based on EPAS technology
Authors: Yao Weijie , Pan Xiaole
Published: February 2023

The physical and chemical characteristics of atmospheric aerosol particles are complex in urban areas. It is of great significance to clarify the influence of different emission sources on atmospheric chemical components for tracing and fine control of air pollution. In this study, passive aerosol samplers were used to collect samples in urban area and steel industrial area in Rizhao, a typical coastal city in eastern China, the collected samples were analyzed by intelligent scanning electron microscope environmental particle analysis system (IntelliSEM-EPAS), which is based on computer-controlled scanning electron microscopy technology. The results show that the atmospheric particulates in Rizhao city are mainly composed of irregular carbonaceous particles, sulfur-containing particles and mineral particles, the number contribution of C-rich particles in urban samples is 53.5%, which is 2.5 times higher than that in steel industrial area samples, the number contribution of particles greater than 1 μm was 9.0%, which is 1.7 times that of the samples in steel industrial area, urban dwellers' activities and industrial processes are the main sources of atmospheric particulate matter in urban area. In steel industrial area, the number contribution of sulfur-containing particles is 72.9%, the mass contribution of sulfur-containing particles is 30.9%, and the mass contribution of iron rich particles is 5.3%, which are 1.8 times, 3.6 times and 2.9 times higher than that of urban samples, respectively. These results indicated that primary pollutants emitted by iron and steel enterprises and secondary formation are the main sources of atmospheric particles in steel industrial area, which has a significant impact on the composition of regional atmospheric particulates.
Parameterizing the evolution of active regions from emergence to eruption. Recent results and future work.
Authors: Kontogiannis Ioannis
Published: February 2023

The emergence of magnetic flux in the Sun can lead to the formation of active regions with highly complex magnetic fields, evident by δ-spots, filaments, and sigmoids. These regions are often the sources of major flares and coronal mass ejections (CMEs) and monitoring their evolution is crucial for a deeper understanding of these phenomena as well as space weather applications. To this end, high-quality observations of the photospheric magnetic field are routinely used to derive parameters and physical magnitudes, and quantify the magnetic complexity of active regions. Thus, we know that eruptive active regions are associated with highly non-potential magnetic field configurations, with strong electric currents and huge amounts of free magnetic energy and helicity. This talk reviews recent efforts to parameterize this non-potentiality of active regions and discusses ongoing and future work on developing new and improved parameters suitable for flare and CME prediction. It further focuses on the evolution of net electric currents in active regions, from their emergence to eruption. The significance of net electric currents on flare and CME prediction and new ways to utilize them in order to produce improved eruptivity parameters and understand solar eruptions will be discussed.
Microbial and environmental factors affecting nitrate removal in bio-electrochemical systems (BES)
Authors: Gadegaonkar Sharvari Sunil , Mander Ülo , Espenberg Mikk
Published: February 2023

Excess nitrogen has caused environmental issues by polluting the air and water. Many different processes help remove nitrogen compounds from contaminated soils and waters, and the presence of oxygen is one of the most decisive factors. Denitrification in anaerobic conditions is considered the main removal processes of excessive nitrogen, although lately discovered anaerobic ammonium oxidation (ANAMMOX) and dissimilatory nitrate reduction to ammonium (DNRA) may also have an important role in nitrogen elimination of different systems. To a lesser extent, also nitrification can contribute to nitrogen elimination in watery systems. All previously pointed out removal mechanisms occur in the constructed wetlands and could even be enhanced with the bio-electrochemical systems (BES). BES exploit the ability of the electroactive microorganisms to reduce the oxides of nitrogen.We analyzed various articles treating nitrate (NO3) polluted water in BES and normalized their NO3 removal efficiencies to a common unit (mg liter−1 day−1). We analyzed the effect of various factors such as electrode materials, working mode, type of inoculum, number of chambers, systems’ capacity and the microbial community structure on the NO3 removal efficiencies. The highest removal efficiencies were displayed by granular carbon and carbon cloth used as cathode and anode material, respectively. The electrode materials and operational parameters, such as working mode and number of chambers, were deemed important by the random forest classification algorithm. Continuous mode of operation, denitrifying microbes as inoculum type, and two chamber systems have displayed optimum NO3 removal efficiencies. Feature selection using random forest classification showed the type of inoculum and capacity of the BES were unimportant factors. Proteobacteria and Firmicute were the prominent phyla observed in BES treating NO3 polluted water. Besides the denitrification (abundance of narG, nirS, nirK, nosZI, and nosZII genes) process in BES, there is evidence of electrochemical support for anaerobic ammonium oxidation (ANAMMOX) (abundance of hzsB or ANAMMOX specific 16S rRNA gene) and dissimilatory NO3 reduction to ammonium (DNRA) (abundance of nrfA gene) processes. The results of this work aid in understanding the prevalent processes in the BES and help to build efficient BES for optimum NO3 removal.
Physics-Informed Neural Networks for Statistical Emulation of Hydrodynamical Numerical Models
Authors: Donnelly James , Daneshkhah Alireza , Abolfathi Soroush
Published: February 2023

The application of numerical models for flood and inundation modelling has become widespread in the past decades as a result of significant improvements in computational capabilities. Computational approaches to flood forecasting have significant benefits compared to empirical approaches which estimate statistical patterns of hydrological variables from observed data. However, there is still a significant computational cost associated with numerical flood modelling at high spatio-temporal resolutions. This limitation of numerical modelling has led to the development of statistical emulator models, machine learning (ML) models designed to learn the underlying generating process of the numerical model. The data-driven approach to ML involves relying entirely upon a set of training data to inform decisions about model selection and parameterisations. Deep learning models have leveraged data-driven learning methods with improvements in hardware and an increasing abundance of data to obtain breakthroughs in various fields such as computer vision, natural language processing and autonomous driving. In many scientific and engineering problems however, the cost of obtaining data is high and so there is a need for ML models that are able to generalise in the ‘small-data’ regime common to many complex problems. In this study, to overcome extrapolation and over-fitting issues of data-driven emulators, a Physics-Informed Neural Network model is adopted for the emulation of all two-dimensional hydrodynamic models which model fluid according the shallow water equations. This study introduces a novel approach to encoding the conservation of mass into a deep learning model, with additional terms included in the optimisation criterion, acting to regularise the model, avoid over-fitting and produce more physically consistent predictions by the emulator.
Effect of initialisation within a 20yr multi-annual climate prediction system
Authors: Düsterhus André , Brune Sebastian
Published: February 2023

Decadal climate predictions use state-of-the-art climate models and combine them with initialisation procedures to create information about our future. Their development has proven successful in the past years and offer a wide range of applications. One of them is the option to learn about the used climate models. With predictions usually aiming at time periods up to ten lead years it is often assumed that initialisation will wear off over time and the model will regress to results comparable to uninitialised simulations.This contribution investigates decadal predictions over lead times of up to twenty years. The decadal prediction system is based on the Max Planck Institute Earth system model (MPI-ESM), uses atmospheric nudging and an oceanic Ensemble Kalman filter for initialisation and is applied for periods from 1960 onwards. We demonstrate that the effect of initialisation within the prediction can be found for long lead years and does not necessarily regresses back to the uninitialised simulation.We show that in some areas the prediction skill varies over time, while in others it persists or drops quickly. Examples are a consistently increased prediction skill compared to historical simulations in the North East Pacific or decreased prediction skill for lead years longer than ten in the South Atlantic. We also take a look at the Atlantic Meridional Overturning Circulation (AMOC) and its development over time. We show that the AMOC drifts on short time scales towards a new state, which is reached after about ten lead years. For decadal predictions with MPI-ESM we find that for large areas of the globe the correct determination of future developments of external forcings plays an important role. This asks the question whether the current approach to hindcasts is appropriate to determine our capability to predict the future.
Tracking volcanic, plutonic, and pegmatitic sources in sediments: implications for the Early Earth history
Authors: Fonseca Teixeira Ludmila Maria , Laurent Oscar , Troch Juliana , Siddoway Christine S. , Bachmann Olivier
Published: February 2023

Understanding magmatic activity on the Early Earth remains a challenge for geoscientists, as most of its rock record has been destroyed or altered. The oldest exposed rocks belong to the Tonalite-Trondhjemite-Granodiorite (TTG) plutonic suite, only rarely associated with volcanic units of the same age. For this reason, TTGs are often interpreted as magmas that have not erupted, and their compositions thought to represent melts. However, if TTGs are the left-overs from shallow magma reservoirs that have lost some melt to the now-eroded volcanic record, their bulk composition would be at least partly biased towards crystal cumulates. As post-emplacement metamorphism typically overprints many of the chemical characteristics of the initial magmatic minerals, the more resistant magmatic minerals (quartz and zircons) within sedimentary successions derived from these systems provide the best chance of identifying volcanic lithologies that have been completely eroded. Here we use a novel approach to show that Ti-in-quartz and Ti-in-zircon thermometers can be used to recognise different magmatic sources in sedimentary rocks. In quartz, Ti thermometry calibrated against blue cathodoluminescence obtained from scanning electron microscopy allows for fast and statistically meaningful Ti quantification in hundreds of sedimentary quartz grains. This imaging-derived Ti distribution matches well with the distribution of Ti concentrations obtained by LA-ICP-MS spot measurements of individual crystals. We compare this quartz record to Ti distributions in zircons, which have the benefit of also providing a crystallisation age. We applied these techniques to the Pikes Peak Batholith (CO, USA), a 1.1 Ga A-type granite hosting several pegmatites, and the Tava sandstone, a series of Cryogenian intra-granite sedimentary dikes that represents the oldest terrestrial sediments in the Front Ranges of Colorado. Our data successfully separates plutonic from pegmatitic crystals and shows that quartz and zircon crystals in the Tava Sandstone crystallised at statistically higher temperatures than the ones observed in the Pikes Peak Batholith, implying potential contribution from a volcanic source that is no longer available on the surface. The proposed techniques can therefore be used to identify eroded magmatic lithologies and to estimate proportions of different magmatic components (volcanic, plutonic, pegmatitic) in sediments.
How Low Can You Go? Implications of Spatial Aggregation for the Estimation of Ecosystem Resilience
Authors: Smith Taylor , Boers Niklas
Published: February 2023

Spatial and temporal aggregations are common when preparing remote sensing data for analysis. Aggregations often serve to enhance the underlying signal of interest while suppressing noise, and can improve estimations of mean states and long-term trends in data. However, aggregating means that the highest-resolution parts of a signal can no longer be resolved, and rapid or fine-scale fluctuations are removed, potentially biasing analyses that rely on these parts of the signal. Further, data aggregation often goes along with gap-filling, which can further dilute the signals of interest.In this work, we examine the impact of spatial aggregation on estimates of vegetation resilience by comparing MODIS vegetation data sets at a range of spatial resolutions (native 250 m – 25 km). We first use synthetic data to investigate various de-seasoning and de-trending schemes and their responsiveness to gaps in the underlying data. Based on these insights, we calculate two estimates of vegetation resilience at the global scale and at multiple spatial resolutions to determine the optimal level of spatial aggregation for MODIS data, considering the tradeoffs between fine-scale (gappy, noisy) and aggregated (continuous, smooth) vegetation data in terms of resilience estimation. Our results provide best practices for the aggregation, deseasoning, detrending, and analysis of vegetation resilience at the global scale.
Implications for Possible Fault Zones Deduced from Lithogeochemical Characterization of Reservoir Levels of a Geothermal Field: Edremit Example
Authors: Elidemir Sanem , Güleç Nilgün , Deniz Kıymet , Kadıoğlu Yusuf Kağan
Published: February 2023

Investigation of the reservoir lithology of Edremit geothermal field from western Anatolia is performed using the drill cuttings that belong to the reservoir levels. The samples are analysed in an attempt to determine the mineralogical and petrographical features, mineral compositions and whole rock geochemistry. The examinations include macroscopic and microscopic analyses, followed by the techniques of X-Ray Diffraction (XRD), Confocal Raman Spectroscopy (CRS), Electron Probe Micro Analysis (EPMA) and X-Ray Fluorescence (XRF). Dominant rock fragments and mineral phases are identified as granitic rocks and quartz, feldspars, micas, carbonates and amphiboles, respectively. Textural characteristics of the samples display the effects of cataclasm and alteration, indicating faulting and hydrothermal fluid activity. The changes in major and trace element concentrations along the well bore reveal three different concentration levels at depth intervals of 900-928 m, 930-974 m and 976-1038 m as well as an inverse relationship between SiO2 and CaO. These three distinctive zones correlate well with the variations in grains sizes (coarse to fine) and textural features (cataclastic to mylonitic) with depth. Taking into account the reported water leakage zone around 930 m depth and the evidences for hydrothermal fluid effect (such as pyrite abundance, alterations, sulphur presence) observed along the well bore, possible fault zone and as a result, the likely pathway for the hydrothermal fluid is inferred to be in the middle section (930-974 m) of the identified three zones. It is also deduced from the lithogeochemical results that the fluid is potentially Si-rich in this zone and Ca-rich in deeper levels which are in line with the previously investigated hydrogeochemistry of the system. This study points out that mineralogical-petrographical studies integrated with geochemical analyses can potentially serve as significant indicators in determination of lithological variations that can be correlated with fault zones of deep systems for prospective exploration sites. This study has been published in Applied Geochemistry in 2022 and complete work can be accessed from https://doi.org/10.1016/j.apgeochem.2022.105388
Building the inorganic carbon budget of a young, actively extending carbonate-rich mountain range: the interplay between chemical weathering and tectonics
Authors: Erlanger Erica , Bufe Aaron , Paris Guillaume , D'Angeli Ilenia , Pisani Luca , Kemeny Preston , Stammeier Jessica , Haghipour Negar , Hovius Niels
Published: February 2023

Mountain building has classically been linked with CO2 drawdown from silicate weathering in the critical zone, although recent views on mountain building recognize the importance of rock-derived CO2 emissions from other organic and inorganic carbon sources. However, the focus on critical zone weathering reactions during mountain building does not consider the emission of metamorphic CO2 from subduction processes in the crust and mantle. Such deep carbon sources could outpace the surficial drawdown and release of carbon, in particular in actively extending mountain ranges that subduct large volumes of carbonate rock. Thus, accounting for weathering processes at depth and in the critical zone in parallel is crucial to fully assess how mountain-range uplift impacts the carbon cycle. Here, we quantify the exchange of CO2 between rock and the atmosphere from subduction-related processes and from critical zone weathering reactions in two major river systems in the central Apennine Mountains of Italy. The catchments straddle a geodynamic gradient across the subduction zone that is expressed as changes in surface heat flow and crustal thickness, whereas climatic boundary conditions are relatively constant.  At the regional scale, we find that metamorphic CO2 sources outpace critical zone inorganic carbon sources and sinks by 2 orders of magnitude above a window in the subducting slab that is characterized by high heat flow and low crustal thickness, and could have driven efficient degassing over the last 2 Ma. In contrast, surficial weathering processes dominate the carbon budget where crustal thickness is greater and heat flow is lower. Importantly, the difference in metamorphic degassing fluxes across the geodynamic gradient is multiple orders of magnitude larger than the difference in critical zone weathering fluxes. Thus, modulations of metamorphic decarbonation reactions are the most efficient process by which tectonics can regulate the inorganic carbon cycle in the Apennines. Both near-surface and deep sources of CO2 must be considered when constructing the carbon budget of orogenic systems that include the subduction of carbonate rock.
Precipitation and temperature variability in Vietnam during Marine Isotope Stage 3 from terrestrial biomarkers
Authors: Tran Trang , Stevens-Landon Lora , Tierney Jessica , Murphy Patrick , Vu-Van Tich
Published: February 2023

Southeast (SE) Asia is located in a transitional zone where hydroclimate is controlled by both the Indian and East Asian summer monsoon branches. Recent proxy-based studies and climate models suggest that the hydroclimate of SE Asia may be out of phase with neighboring regions, such as India and China. However, we lack sufficient proxy records to verify this postulation or to identify spatial and temporal variations. This study reconstructs both past temperatures and effective moisture in Central Vietnam during Marine Isotope Stage 3 (approximately 50,00 to 30,000 years BP) to determine how these two climate variables relate in the past. Terrestrial temperatures and precipitation are reconstructed using biomarkers (branched glycerol dialkyl glycerol tetraethers, brGDGT) and compound-specific isotope analyses (carbon and hydrogen-isotopic values of leaf wax n-acids, δ13Cwax, and δDwax) from a buried peat deposit in the Central Highlands of Vietnam. The brGDGTs-derived annual temperatures range from 22.9 to 26.2°C and show a warming trend coincident with a weakening of summer insolation. A coincident and gradual enrichment of δ13Cwax from 47 to 33 kyr BP suggests a transition from C3 to C4 vegetation dominance. Such a response could signal an overall decrease in precipitation or a shift in the seasonality of precipitation. The δDwax data, however, do not indicate an overall drying trend, which supports the idea that a shift in the seasonality of rainfall, along with higher annual temperatures, is driving the vegetation change. In addition, the δDwax records may exhibit a trend opposite to a site in Thailand. We argue that the isotopic variability in the precipitation of Central Vietnam reflects the shift in moisture sources along with the shift in seasonality. In this case, an increase in amount of precipitation derived from the South China Sea in winter months is marked by rain enriched in δ2H-which could also be interpreted as a decrease in precipitation. The increase in rainfall during winter monsoon months (e.g. winter) in the Central Highlands of Vietnam does not appear to reach Thailand. We recommend that the precipitation proxies should be applied with knowledge of regional climate context and argue that better geographic representation of monsoonal climates is necessary to fully understand and model this critical climate system.
New ocean spreading beneath the Arabian Shield controlled by LAB-structure
Authors: Thybo Hans , Artemieva Irina , Yang Haibin
Published: February 2023

Formation of new oceans by continental break-up is traditionally understood as a continuous evolution from rifting to ocean spreading. Here we show that already the break-up phase may involve a jump of extensional axis, as earlier observed in e.g. the mature North Atlantic Ocean. The Red Sea is one of few locations on Earth where a new plate boundary presently forms. The new plate boundary is already active in the southern Red Sea oceanic spreading centre, but the north-central segment is still in a continental rifting stage, and the associated magmatism is offset by ca 300 km into Arabia.This situation is similar to the Baikal Rift Zone, where the rift-related magmatism in the north is offset by 200-300 km into the Sayan-Baikal Fold Belt, but not offset in the south. Our earlier numerical modelling has shown that the location of the magmatism may be controlled by thinning of the lithosphere from the Siberian Craton into the fold belt, whereas the rift location is controlled by pre-existing crustal scale weakness zones (Yang et al., 2018).Here, we propose a new geodynamic model for the evolution of the Red Sea region which is consistent with all geological and geophysical observations. We demonstrate that the north-central rift is a transient feature that will not develop into coincident ocean spreading. Instead, a new plate boundary forms across Arabia. Our numerical experiments predict that in 1–5 Myr the north-central extensional axis will jump ~300 km eastward into Arabia. The existing Ad Damm strike-slip fault, perpendicular to the central Red Sea rift axis, will evolve into a transform fault between the on-going ocean spreading in the southern Red Sea and the future spreading in north-central Arabia.We demonstrate that crustal-scale weakness zones can control lithosphere extension and lead to long-distance jumps of extensional axes in continental lithosphere not affected by hotspots. Therefore, our model also provides theoretical basis for understanding dynamics and mechanisms of the transition from rifting to continental break-up at passive continental margins not affected by hotspots.
Effect of anomalous high-pressure in Eastern Europe on the prediction of 2018 East Asian heatwave
Authors: Kang Jinhee , Wie Jieun , Lee Sang-Min , Lee Johan , Kim Baek-Jo , Yun Semin , Moon Byung-Kwon
Published: February 2023

In 2018, a severe and long-lasting heatwave in East Asia resulted in significant socio-economic damage. To possibly reduce losses, it is necessary to understand the mechanisms of heatwaves and increase their predictability. In this study, we identify the patterns of geopotential height responsible for the 2018 East Asian heatwave from ERA5 observation and compare them with simulations using Global Seasonal Forecasting System version 6 (GloSea6). The K-means clustering analysis reveals an anomalous high-pressure pattern in Eastern Europe, which is mainly associated with the 2018 East Asian heatwave. GloSea6 experiments were then conducted with various initial conditions. Notably, GloSea6 runs reproducing the observed high-pressure anomaly in Eastern Europe shows a good prediction of the 2018 East Asian heatwave. Sensitivity experiments further highlight the lack of soil moisture in Eastern Europe seems to be a key factor for the anomalous high-pressure pattern there, resulting in the 2018 East Asian heatwave. Our results imply that model- and observation-consistent representations of soil moisture in Eastern Europe are required to reduce the uncertainty in predicting the East Asian heatwaves.This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMI2020-01212. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No. 2022R1A2C1008858).
Snowpack nitrate photolysis drives the summertime atmospheric nitrous acid (HONO) budget in coastal Antarctica
Authors: Bond Amelia M. H. , Frey Markus M. , Kaiser Jan , Kleffmann Jörg , Jones Anna E. , Squires Freya A.
Published: February 2023

In the polar regions, the usual OH radical formation pathway (ozone photolysis and reaction of O(1D) with H2O) is limited by the low water vapour concentration. However, gases emitted from the snowpack can be pre-cursors of HOx radicals and ozone, thereby controlling the oxidising capacity of the lower atmosphere above remote snow-covered regions.Snowpack photolysis of nitrate and the resulting emissions of the reactive nitrogen species NOx and HONO can lead to OH production through rapid cycling of RO2 → HO2 → OH and photolysis of HONO. Research into reactive nitrogen species in polar environments has focused on NOx, with far fewer investigations into HONO. Previous studies of HONO in the polar boundary layer and snowpack interstitial air suggest a photolytic snowpack source but the exact mechanism for HONO production is poorly understood; photochemical models of HONO sources and sinks often cannot be reconciled with the measured HONO concentrations.A LOng Path Absorption Photometer (LOPAP) was used to investigate the net HONO flux density above snow in the Clean Air Sector at Halley VI Research Station in coastal Antarctica during Austral summer 2021/22. We present amount fraction measurements of HONO in ambient air, as well as measurements of the HONO flux density between the snow and atmosphere by the flux-gradient method. The potential snowpack reactions driving this HONO release are discussed, as well as the implications of these measurements for the HOx budget. These findings help further our understanding of the atmospheric budget of reactive nitrogen and highlight the significant effects snow surfaces can have on the atmospheric chemistry in the boundary layer above.
Climatic and environmental changes in the North Sea Basin during the Early Miocene
Authors: Fredborg Julie Margrethe , Sistiaga Ainara , Soltau Emil Munck , Dybkjær Karen , Piasecki Stefan , Rasmussen Erik Skovbjerg , Thibault Nicolas , Sliwinska Kasia Kamilla
Published: February 2023

The Miocene Climatic Optimum (~17 to 14 Million years ago) has recently gained attention as a future climate analogue. However, the number of climatic records from the northern high and middle latitudes is very limited, so the global impact across this climatic transition is still poorly understood. The most northernly located site penetrating a nearly complete Miocene succession is located in the eastern North Sea Basin (Sdr. Vium borehole, Denmark). This research provides a multi proxy investigation performed on the Lower Miocene part of the succession. The studied interval corresponds with the time leading up to the onset of the Miocene Climatic Optimum. A total of 44 samples have been studied for their relative abundances of major palynological groups (dinocysts, acritarchs, spores, non-saccate pollen, saccate pollen and freshwater algae) and for the dinocyst/pollen ratio. In addition, 11 selected palynological samples were studied for their content of  dinocyst and acritarch taxa (counting a minimum of 200 specimens per sample). 77 samples constitute the basis of a HH-XRF based chemical analysis. Furthermore, the n-alkanes of 8 samples have been analysed in order to assess their potential within a paleoenvironmental context. This study provides an updated age model (derived from dinocysts) and sequence stratigraphy of the Burdigalian (Early Miocene) succession of the Sdr. Vium core. The studied interval belongs to the Sumatradinium hamulatum Zone, the Cordosphaeridium cantharellus Zone and the Exochosphaeridium insigne Zone.  XRF analysis combined with palynology improved the existing sequence stratigraphical framework of the studied site. Furthermore, the low resolution record of the n-alkanes show a good correlation between high content of the C23-25 and position of sequence boundaries.  The changes in the relative abundance of warm-water dinocysts as well as alkenone-derived sea surface temperature suggest a brief interval of colder sea surface conditions just prior to the onset of the Miocene Climatic Optimum.   