bluuebunny/crossref_metadata_2025 huggingface dataset:
SAIPy: A Python Package for single station Earthquake Monitoring using Deep Learning
Authors: Srivastava Nishtha , Li Wei , Chakraborty Megha , Cartaya Claudia Quinteros , Köhler Jonas , Faber Johannes , Rümpker Georg
Published: March 2024

Seismology has witnessed significant advancements in recent years with the application of deeplearning methods to address a broad range of problems. These techniques have demonstrated theirremarkable ability to effectively extract statistical properties from extensive datasets, surpassing thecapabilities of traditional approaches to an extent. In this study, we present SAIPy, an open-sourcePython package specifically developed for fast data processing by implementing deep learning.SAIPy offers solutions for multiple seismological tasks, including earthquake detection, magnitudeestimation, seismic phase picking, and polarity identification. We introduce upgraded versionsof previously published models such as CREIME_RT capable of identifying earthquakes with anaccuracy above 99.8% and a root mean squared error of 0.38 unit in magnitude estimation. Theseupgraded models outperform state-of-the-art approaches like the Vision Transformer network. SAIPyprovides an API that simplifies the integration of these advanced models, including CREIME_RT,DynaPicker_v2, and PolarCAP, along with benchmark datasets. The package has the potential to beused for real-time earthquake monitoring to enable timely actions to mitigate the impact of seismicevents.
Recycled Aggregates Effects on Acid Minesoils Response to Rainfall Events: Short-Term Study
Authors: Barba-Brioso Cinta , Delgado Joaquín , Campos Paloma , Martín Domingo , Romero-Baena Antonio
Published: March 2024

This investigation focused on the response of minesoils to which an upper substrate of recycled aggregates was added. The experience consisted in a first characterization of the minesoils (February’23) and two sampling after rainfall events, occurred in consecutive months (March and April’23). Soil sample reaction (pH-Eh and electrical conductivity) was studied with a portable multiparametric, chemical composition was analysed by X-Ray fluorescence and mineralogy was assessed by X-Ray diffraction and electron microscopy SEM.Results showed that soil surface became less acidic, changing from 3.6 to up 6 units of pH. It was probed that the alkalinizing lost reactivity at depth, since level b and c were progressively more acid, but also that it was being depleted in time. Redox conditions, nevertheless, behaved in distinct way, increasing at the three levels in time, that could affect the distribution of elements. In fact, content of Al, Fe and S slightly decreased in surface with time, but specially Al increased in depth, suggesting any mobilization to leader elements. On the other side, trace elements, specially As, trended to concentrate at the intermediate level, marking the importance of redox conditions in their distribution.Initial mineralogy hardly varied along time, maintaining the presence of the main minerals (quartz, mica and jarosite from the soil and calcite and dolomite from the amendment). Anyway, bassanite appeared during treatment, at the time than calcite and dolomite were depleted, showing the interaction of those with sulphur liberated from the oxidized pyrite observed by SEM.
Zircon U-Pb and Hf petrochronology of mafic high-grade rocks of a Neoproterozoic nappe system in West Gondwana (Socorro Nappe, SE Brazil)
Authors: Balis Mikaella , Schulz Bernhard , Campos Neto Mario da Costa
Published: March 2024

In the Southern Brasília Orogen (south-eastern Brazil), a nappe system that represents the roots of a magmatic arc records HT-UHT metamorphic conditions in lower to mid-crustal rocks. It is divided into two segments by a major shear zone, of which the northern nappe hosts the most extreme metamorphism and has been targeted for most petrochronological studies. These rocks carry insights into the stages of orogeny, as well as the first direct evidence of the paleo-active margin basement, and time-constraint (1) a metamorphism related to the magmatic arc consolidation on the active margin at 670-640 Ma and (2) an enduring UHT event related to collision and decompression at 630-590 Ma. The southern nappe (Socorro Nappe) hosts felsic and mafic granulites, amphibolites and migmatites with intricate occurrences and complex pressure-temperature-time histories that may preserve distinct age populations in the inner nappe and its outward boundaries (Embu Terrane and São Roque Domain). The mafic lower to mid-crustal rocks of the Socorro Nappe lack detailed comprehensive studies of their P-T-t evolution. We present new preliminary LA-ICPMS U-Pb and Lu-Hf systematics in zircon retrieved from metamafic rocks such as granulites, amphibolites and orthogneisses, and partial results on conventional thermobarometry and thermodynamic modelling. We investigate the significance of a wide timespan from ca. 750 to 570 Ma where granulites tend to preserve older ages in contrast to amphibolites. However, Hf signatures are complex and also show a wide range of ε values from 0 to weakly radiogenic, and strongly radiogenic that are not straightforwardly related to a clear time evolution. Herein we discuss preliminary insights into the zircon petrochronology and P-T-t evolution of metamafic high-grade rocks as a tool to unravel the tectonic evolution of the southernmost segment of the Southern Brasília Orogen in relation to the adjacent São Roque Domain and Embu Terrane, in the context of the Western Gondwana amalgamation. 
Unveiling global sub-daily precipitation extremes: Insights and development of the INTENSE Project 
Authors: Fowler Hayley , Green Amy , Lewis Elizabeth , Pritchard David , Blenkinsop Stephen , Patino Velasquez Luis , Whitford Anna
Published: March 2024

Precipitation extremes result in flooding and droughts, causing substantial damages and loss of life. Understanding the variability of precipitation extremes with climate change is challenging, as we do no fully understand processes causing extreme precipitation under current climate variability. The INTENSE project focuses on understanding of the nature and drivers of global sub-daily precipitation extremes and change on societally relevant timescales. As part of this a Global sub-daily precipitation dataset has been collected, containing hourly rainfall data from approximately 25,000 rain gauges across over 200 territories, from a wide range of sources. This has been quality controlled using a rule-based open-source methodology, combining a number of checks against neighbouring gauges, known biases and errors, and thresholds based on the Expert Team on Climate Change Detection and Indices (ETCCDI) Climate Change Indices.  

A set of global hydroclimatic indices have been produced, characterising key aspects of shorter duration precipitation variability, including intensity, duration and frequency properties. An analysis of the indices, trends and corresponding climatology is carried out, providing information on various sub-daily precipitation characteristics (including extremes) across large parts of the world. These indices are publicly available for as many gauges as possible, alongside a gridded dataset that also incorporates indices calculated for additional restricted-access gauge records. To progress further with this work, updates to the dataset are required, with work ongoing to update resources for 2016 onwards, and attempts to automate the process where open-source datasets are available. Any collaborations, information, suggested contacts and relevant resources for developing the dataset are welcomed. 
Forward Model for Subsurface Retrievals of Icy Moons
Authors: wang Suyun , Yamada Takayoshi , Kasai Yasuko
Published: March 2024

We develop a radiative transfer model including scattering for Icy moon. We model it as a random medium with rough top and bottom boundaries and a host medium situated beneath. The total scattering and emission consists of three sources:  rough boundaries, the volume, and the boundaries and the volume interactions. To account for these sources, we model their respective phase matrices and apply the matrix doubling approach to couple these phase matrices to compute the total emission. The model is then used to explore insights into Icy moon scattering and emission processes. The developed model is readily applied to physical parameters inversion of icy moons.
High-resolution exploration of transiting sub-Neptunes’ atmospheres with NIRPS
Authors: Mounzer Dany , Lovis Christophe , Allart Romain
Published: March 2024

Atmospheric characterization of smaller exoplanets has entered a new era with the capabilities of JWST and the latest high-resolution spectrographs such as NIRPS, in combination with HARPS on the ESO 3.6m at La Silla, which has started operations on April 1st, 2023. By the start of the EGU General Assembly 2024, the NIRPS consortium has scheduled 25 transits of more than 10 sub-Neptunes (< 3 REarth) not named TRAPPIST-1, and many more to come during the 725 total nights of NIRPS Guaranteed Time Observations (GTO).In this talk, we present an early overview of the high-resolution transmission spectroscopy analysis of those targets, looking for a wide range of atomic and molecular species both in infrared and in the visible, and compare those results with the latest JWST findings for those targets. We show that NIRPS observations lead to some of the most precise transmission spectra in the metastable helium region ever produced, strongly constraining this element's presence or lack thereof in the upper atmosphere of exoplanets.
Environmental stability of MEMS gravimeters.
Authors: Passey Elizabeth , Prasad Abhinav , Toland Karl , Anastasiou Kristian , Paul Douglas , Hammond Giles
Published: March 2024

Wee-g is a new gravimeter that utilises a micro-electromechanical system (MEMS) sensor. The use of MEMS-based sensors has benefits as a new gravimetry technology because the low cost of the base material silicon and accessibility of manufacturing facilities will enable increased availability of gravimeters. However, the challenge of working with silicon for a gravimetry device is its thermal sensitivity, which affects the Young's Modulus of the material. In the context of Wee-g's sensor design, when the flexures that support the proof mass become softer because of temperature changes, under gravity the proof mass change position. Changes to the ambient pressure can also result in changes to the proof mass position. Wee-g has a thermal control system that effectively controls the temperature at the sensor to within 1mK, but field observations indicate that large changes to ambient environmental conditions can be coupled to the sensor output. Here we present the results of environmental stability tests conducted on a Wee-g field prototype with implications for its performance in field environments that vary in temperature and pressure significantly.
Investigating the Impact of Time Series Structure in Performance of Transformer-Based Model for River Streamflow Forecasting
Authors: Tepetidis Nikolaos , Iliopoulou Theano , Dimitriadis Panayiotis , Koutsoyiannis Demetris
Published: March 2024

River discharge forecasting plays a pivotal role in water resource management and environmental planning. Understanding the long-term dependence or changes in these processes is crucial for accurate predictions. Deep-learning methodologies have garnered significant scientific interest and are progressively becoming more prevalent across water-resources-related endeavors. Transformer models, a novel architecture that aims to track relationships in sequential data through attention mechanism, have increasing popularity last years. Through comprehensive experiments and analysis on real-world river discharge datasets, we aim to elucidate the impact of long-term dependence detection, as facilitated by the climacogram and Hurst coefficient, on the predictive capabilities of a transformer-based model. Insights from this investigation are anticipated to contribute to the advancement of river discharge forecasting methodologies, enhancing our understanding of long-term dependencies in these environmental processes.
Next steps towards the Tipping Point Modelling Intercomparison Project (TIPMIP)
Authors: Dennis Donovan , Donges Jonathan , Loriani Sina , Sakschewski Boris , Winkelmann Ricarda
Published: March 2024

Anthropogenic climate change poses considerable risk to the stability of the Earth system. The consequences associated with crossing certain tipping thresholds, wherein relatively small-scale changes in the state of a specific tipping element may induce widespread and potentially irreversible feedbacks, are among the most severe. The Tipping Point Modelling Intercomparison Project (TIPMIP, www.tipmip.org) seeks to systematically investigate tipping risks for the Greenland and Antarctic ice sheets, the Atlantic Meridional Overturning Circulation, tropical and boreal forests as well as high-latitude permafrost  in order to both advance the understanding of the underlying  dynamics as well as to quantify the associated uncertainties around crossing such thresholds. Here, we discuss the initial proposed experimental protocols for TIPMIP for each domain (cryosphere, ocean, biosphere, fully coupled), the next  steps towards their implementation within the modelling community as well as the alignment with other ongoing and planned MIPs. 
Radon measurements in work environments for underground water extraction in an area of central-north Italy with low potential risk: a concrete case of passive/active measurements in the workplace and active measurements in water by LSC.
Authors: Taroni Mattia , Iannarone Andrea , Zambelli Giacomo
Published: March 2024

The measurement of Radon gas is now a consolidated activity: the impetus given by the new regulations and technical guides, in addition to the awareness of the health risks linked to high exposures to the gas, have made it possible to increase controls even in geographical areas considered potentially at low risk, bringing out critical situations for workers and the population.
This work presents the results of passive and active measurement campaigns of Radon gas in an area of Emilia Romagna in workplaces responsible for the extraction of water from underground and for its distribution. 
Monitoring carried out in groundwater collection sites such as sources and outlets in the mid-Apennine area has instead highlighted the presence of significant concentrations of Radon which will be higher than the reference level, reaching 46,000 Bq/m3 in some cases.
Radon measurements were followed in the distributed waters using Liquid Scintillation Counting to complete the passive measurements: the results show a shallow level of radon in the drinking water, minus the 30 Bq/lt.The action remediation has permitted the Radon concentration reduction in the workplace with a gas level very close to the parametric value of Radon, 300 Bq/m3. 
How does bed load transport influence the longitudinal profile of reservoir sedimentation?
Authors: Zeng Xin , Yuan Yuan
Published: March 2024

The construction of the reservoir has destroyed the equilibrium of the natural river and promoted the siltation of a large amount of sediment in the reservoir. The longitudinal profile after reservoir siltation will have a great impact on the amount of the reservoir siltation, the retention of effective reservoir capacity, and the raise of water elevation caused by the backwater effect. Therefore, the estimation of the longitudinal profile is of great significance to the calculation of the reservoir sedimentation. For mountain rivers, the amount of bed load usually accounts for a large proportion of the total sediment load, which affects the longitudinal bed profile after dam construction. Because the amount and gradation data of bed load are often not available, the effects of bed load transport on the longitudinal profile of reservoir sedimentation cannot be accurately simulated. Until now, how bed load transport influences the longitudinal profile of reservoir sedimentation has not been fully understood. The motivation of our study is to clarify the effects of bed load transport on the longitudinal bed profile of reservoir sedimentation. We use a 1D mathematical model to study the evolution of the longitudinal bed profile after dam construction to answer the question. Various scenarios with different boundary conditions are considered to analyze the effects of bed load, such as the amount, gradation and distribution during the year, on the longitudinal bed profile after dam construction. Our results show the effect of the amount of bed load on the longitudinal bed profile of reservoir sedimentation.is greater than that of bed load gradation and distribution during the year. In the early stage of reservoir operation, the influence of the bed load transport on the longitudinal profile is negligible. With the increase of operation time, the effects of bed load becomes more and more significant. The larger the amount of bed load, the higher the bed elevation, and the larger the slope of the riverbed near the dam. For areas with large initial topographic slopes, the greater the bed load amount, the smaller the slope of the riverbed after siltation. In contrast, the effects of bed load gradation and distribution during the year.on the longitudinal bed profile of reservoir sedimentation is not significant.
Combined Orbit Determination Based on Carrier-Range observation
Authors: Wang Hengyi , Zhou Xingyu , Cui Zilu , Chen Hua
Published: March 2024

In recent years, an increasing number of Low-Earth-Orbit (LEO) satellites have been launched into space, some of which carry at least one onboard GNSS receiver. The combined orbit determination of LEO and GNSS satellites, utilizing onboard GNSS receivers and ground GNSS stations, is of great significance for improving the geometric observation configuration of GNSS satellites and enhancing the accuracy of satellite orbit determination. The aim of this study is to address the key issues in the integration of onboard GNSS observations from LEO satellites and ground-based GNSS observations. Our primary objectives includes exploring methods for fixing single station ambiguity based on integer clocks and subsequently forming carrier range observations, which is the basis of our study on combined orbit determination; establishing a proper stochastic model for integrating onboard GNSS observations with ground-based GNSS observations, by utilizing the variance component estimation; evaluating effects of different narrow lane UPD estimation strategies on the fixed ambiguity rate and orbit determination accuracy, offering an estimation strategies which could balance computational efficiency and accuracy of orbit determination better. Data from LEO satellites such as GRACE-FO, Swarm, Sentinel-6A and data from IGS network are processed in our study for evaluating different strategies and validating our conclusion.
Source- and receiver-coupling effects for time-domain Full Waveform Inversion
Authors: Söding Hagen , Maurer Hansruedi , Fechner Thomas
Published: March 2024

Tomographic techniques have been an indispensable tool for tackling manifold problems in earth and environmental sciences. For wavefield techniques, like seismics and ground penetrating radar, full waveform inversions offer powerful tools for extracting the full waveform information content to obtain high-resolution subsurface images. Although mostly applied to deeper targets (exploration scale), near-surface full waveform information holds a strong potential to analyse the often more complicated subsurface structures both in imaging and monitoring applications. Due to the complexity of the very shallow subsurface, source- and receiver coupling often exhibit substantial variations and can thus not be neglected. Maurer et al. (2012) showed that this problem can be addressed in frequency domain full waveform inversions by including source- and receiver coupling terms as additional unknowns into the inversion workflow. However, there are inherent trade-offs between the source- and receiver coupling factors. This is irrelevant for frequency-domain full waveform inversions, but this problem needs to be addressed for time-domain inversion problems.In our contribution we present two possible options to make source- and receiver coupling inversions also applicable in time-domain problems, using either a parameterized source wavelet or a sparsity regularisation approach. We demonstrate our novel methodology with a synthetic study and with an application to an acoustic seismic full waveform inversion on a CCS study from the Digimon project from Svelvik, Norway. References:Hansruedi Maurer, Stewart A. Greenhalgh, Edgar Manukyan, Stefano Marelli, Alan G. Green; Receiver-coupling effects in seismic waveform inversions. Geophysics 2012;; 77 (1): R57–R63. doi: https://doi.org/10.1190/geo2010-0402.
Simulations of energy and water balances with WRF and WRF-Hydro models: the role of model coupling and parameterizations
Authors: Sofokleous Ioannis , Bruggeman Adriana , Camera Corrado , Djuma Hakan , Amini Fasakhodi Mohsen , Zittis George
Published: March 2024

We tested the widely used atmospheric WRF (Weather Research and Forecasting) model in a coupled mode to the hydrological model WRF-Hydro. The coupled WRF/WRF-Hydro model adds the simulation of horizontal surface and subsurface flow of water relative to the standalone WRF. We conducted simulations for the Mediterranean island of Cyprus and 31 small mountainous river basins for the hydrological year 2011-2012. We found higher soil moisture (20%), more evapotranspiration (33%) and a small increase in rainfall (3%) for the coupled WRF/WRF-Hydro model, compared to the WRF model without horizontal flows. We also forced WRF-Hydro with observed rainfall and five different set-ups of WRF and examined the modelled streamflow. The WRF set-ups were adapted from combinations of different microphysics, cumulus cloud, planetary boundary layer and surface layer schemes. We found that WRF-Hydro with observed rain underestimated the average streamflow by 6%, during a two-year simulation (2011-2013). The best of the five WRF set-ups showed a 19% underestimation of the average streamflow, thus, an optimized ensemble of WRF set-ups is needed to model the streamflow. Our study suggests that the coupling of WRF with the WRF-Hydro model can improve land-atmosphere simulations. We will also present the calibration of parameters of the land surface component of the coupled model with observations of soil moisture and transpiration that could further enhance the ability of the model to represent the different parts of the combined terrestrial-atmospheric water cycle.
Evaluating the MULESME downscaling scheme in retrieving soil moisture content: A case study from Greece
Authors: Detsikas Spyridon E. , Petropoulos George
Published: March 2024

Remote sensing (RS) has a proven capability to retrieve surface soil moisture (SSM) content at different spatiotemporal resolutions and a wide range of techniques have been proposed for this purpose. In recent years, there has been particular interest towards developing techniques for local or regional SSM retrievals. To this end, a very promising approach is MULESME (MUltitemporal Least Square Moisture Estimator), which is capable of producing SSM estimates at 1 km from the synergy of optical and radar data. Its effectiveness has already been demonstrated for producing an operational, national scale SSM product in Italy. The present study evaluates the use of MULESME in predicting regional SSM over selected agricultural sites in Greece. To evaluate MULESME’s performance, a standardized validation procedure was followed employing a series of statistical measures comparing MULESME’s predictions against in-situ SSM data from probes installed at the selected experimental sites. Our findings demonstrate the potential of MULESME in producing accurate regional SSM predictions. Our results can be useful in a wide range of environmental studies and hydrological applications that require knowledge on the spatiotemporal variation of SSM. The present work has been implemented under the framework of Listen-EO (DeveLoping new awareness and Innovative toolS to support efficient waTer rEsources management Exploiting geoinformatiOn technologies), funded by the Hellenic Foundation for Research and Innovation programme (ID 015898).
Investigating Hydrological Connectivity inthe Yamuna River System, India
Authors: Karnatak Nikita , Jain Vikrant , Shekhar Shashank , Padhya Virendra , Deshpande Rajendrakumar Dattatraya
Published: March 2024

Vertical connectivity between groundwater and river discharge is fundamental in maintaining river health. Groundwater sustains baseflow in rivers during lean period, helps in maintaining e-flow, and facilitates the transfer of nutrients and organisms across the hyporheic zone. The present study has been conducted in a ~300 km long alluvial reach of the Yamuna river from the Himalayan mountain front to Delhi National Capital Region (NCR), India. The Yamuna river is the largest tributary of the Ganga River system. It originates from the Higher Himalaya at an elevation of 6387m with an average annual rainfall of 906 mm. Seasonal and downstream variability in vertical hydrological connectivity along long profile was assessed using field measurements and laboratory analysis of stable isotopes.A total of 71 samples from both groundwater and river water were analyzed for δd, δ18O, and d-excess values during both pre-monsoon and post-monsoon seasons of the year 2021. The average δ18O isotopic composition of most of the post-monsoon river water samples exhibit depletion in heavy isotopes in comparison to pre-monsoon samples. Depleted δ18O values indicate increase in rainfall contribution to river water during monsoon period. The low slope of the pre-monsoon groundwater in the graph plotted between δ18O and δd indicate lack of groundwater recharge during pre-monsoon period. This is responsible for higher values of δ18O isotopic composition of the groundwater, which is especially significant in the upstream reaches of Delhi NCR. Seasonal changes are evident only in the reaches upstream of Delhi NCR with similar pattern in groundwater and river water isotopic values. Data indicates a well-developed vertical hydrological connectivity in the upstream reaches. Our field based measurement of river and groundwater head validates the existence of hydrological connectivity in this reach. However, vertical connectivity is not apparent in the downstream reaches around Delhi NCR, as the seasonal changes in the isotopic composition of both river and groundwater are not prominent. Integrating these findings with water depth measurements in the field facilitated that out of 4 sub-reaches of our study area loose water to the groundwater, while 3 sub-reaches are gaining streams. This study will help to identify areas of concern and develop an effective management and conservation strategies to protect and restore the health of the river.
Current and future projections of forest aboveground carbon storage over Northeast China using an advanced deep convolutional neural network 
Authors: Wang Xiaoyi , Lyu Guanting
Published: March 2024

Forests are the largest carbon reservoirs in terrestrial ecosystems, with climate and anthropogenic disturbance have considerably reshaped the size of this system. However, remote sensing estimates to quantify current and future carbon stock are characterized by large uncertainty. Here, we developed a new spatially explicit map of forest aboveground carbon storage at a 30 m spatial resolution across Northeast China, by integrating an image-to-image U-Net deep convolutional neural network algorithm with in situ measurements, Global Ecosystem Dynamics Investigation observations, Landsat, and PALSAR2 images. The result yields a high coefficient of determination (R2) of 0.83 and a relatively low relative root mean squared error of 24.02%, and is superior to traditional pixel-based and in situ-based methods. The forest aboveground biomass carbon stock was estimated as 2.74 ± 0.38 PgC, with precipitation and forest age being important determinants. By developing a climate and age-driven predictive model, local forest biomass C sink is estimated to be 7.42 and 2.51 TgC year-1 for 2060s and 2100s, a significant decline due to aging forests. The study highlights the importance of forest protection and management to optimize forest age structure and sustain natural forest carbon sinks.
Boron isotope fractionation during oceanic-crust dehydration in subduction zones: boron coordination in omphacite
Authors: Xu Jie , Marschall Horst R. , Gerdes Axel
Published: March 2024

Boron has two stable isotopes, 10B and 11B, which are strongly fractionated during geological processes. They have been widely used to trace fluids in subduction zones. The temperature-dependent equilibrium boron isotope fractionation depends on boron coordination in the B-hosting minerals and fluids. In blueschist- and eclogite-facies high-pressure metamorphic rocks, omphacite (Cpx), amphibole and white mica are the dominant hosts of B. Yet, different crystallographic mechanisms of B substitution in Cpx have been proposed with first-order implications for B isotope fractionation during slab dehydration and eclogite formation. Hence, clarification of B coordination in clinopyroxene is desired, but a direct determination of boron coordination in silicates at the trace-element level is not technically possible. In this study, we have thus determined the B coordination in omphacite, glaucophane and mica by indirect means through the investigation of the B isotope fractionation in natural rocks.We investigated a set of six different tourmaline-bearing reaction zone rocks from the high-pressure (HP) mélange on the island of Syros formed at approximately 0.7 GPa, 430 °C. The rocks show the paragenesis tourmaline + phengite + omphacite + glaucophane in textural equilibrium, which offers the opportunity to determine equilibrium B isotope fractionation among these minerals. The proportions of trigonally and tetrahedrally coordinated B in omphacite, glaucophane and phengite was then estimated from the respective boron isotope fractionation against tourmaline. The B isotope fractionation between phengite and tourmaline is -14.7 ±0.6 ‰, and -12.4 ±0.8 ‰ between omphacite and tourmaline. B isotope composition in omphacite is 2.5 ±1.6 ‰ heavier than in phengite. No significant difference was found between glaucophane and phengite. From these results, we conclude that boron in omphacite is dominantly in tetrahedral coordination (84 ±6 % of the total B) with a minor amount of B in trigonal coordination (16 ±6 %).
Understanding Tectonic and Sedimentary Controls for the Reconstruction of the Hydrothermal History in Magma-poor Rifted Margins
Authors: García-Pintado Javier , Pérez-Gussinyé Marta
Published: March 2024

The spatio-temporal reconstruction of the sedimentary and thermal state in magma-poor rifted margins, along with fluid-rock interactions driven by hydrothermal activity is key to support the understanding of processes leading to the accumulation of resources as, for example, base metals and Rare Earth elements, in these settings. One specific example is natural hydrogen, which is becoming a key player in the energy mix. Beyond the various sources of currently produced synthetic hydrogen, a recent focus is being given to natural (white) and stimulated (orange) geological hydrogen. A key production mechanism for the abiotic generation of natural hydrogen is the geochemical process known as serpentinization, which results from the reaction of water with low-silica, ferrous minerals at the adequate pressure and temperature conditions. For serpentinization to occur, the ultramafic rocks in the lithospheric mantle need to fracture to allow for water to infiltrate. This chiefly happens when rocks are mechanically stressed by tectonics, and can be further supported by local stresses generated by the same metamorphic reactions associated to serpentinization. More generally, further understanding of the effects of geological controls and structural plate tectonic positions on thermal and hydrogeologic regimes, as well as their coupling with fluid dynamics, fluid chemistry, fractures and faults, and lithological sequences is needed for the historic analysis of hydrothermal systems. Numerical simulations are suitable for investigating these multicomponent systems, as they allow for sensitivity analyses of individual processes and interactions, including appropriate time and length scales. Here we focus on the continent-ocean transition (COT) of magma-poor rifted margins. By means of basin-scale numerical simulations we analyze the interactions between tectonics, sedimentary and hydrothermal processes. While it has long been acknowledged that the patterns of impermeable sediment blankets are a strong control on hydrothermal activity, here we first show how tectonics and these sedimentary structures relate to patterns of fluid circulation and temperature at the basin scale and at geological scales. We further relate them with historic reconstructions of advective and conductive heat flow in rifted margins, and finally give consideration to the serpentinization and generation of potential natural hydrogen reservoirs.
Distribution of sulfur and oxygen isotopes in rivers of eastern himalayan states: Implications for riverine sulfate source partitioning in coal mining areas of northeast India
Authors: Kumar Vivek , Paul Dibyendu , Kumar Sudhir
Published: March 2024

Stable isotopes of sulfur and oxygen in water can provide valuable information about sources, geochemical and biogeochemical processes, and conditions influencing source to sink movement of sulfur in hydrological systems. Although research on stable isotopes of sulfur and oxygen in water has gained momentum worldwide, there are limited study from water bodies in the eastern himalayan states of northeast India. The present study was conducted in the eastern himalayan states of northeast India, in rivers flowing nearby Namchik-Namphuk Coalfields in Arunachal Pradesh, Makum Coalfields in Assam, coal mining areas near Changki village in Mokokchung district of Nagaland, and Bapung coalfields in Jaintia Hills region of Meghalaya. Water samples were collected from twenty-one (21) sampling stations and analyzed for major ions, sulfur and oxygen stable isotopes (δ34SSO4 & δ18OSO4) in sulfate and hydrogen and oxygen stable isotopes (δDH2O  & δ18OH2O ). δ18OH2O and δ18OSO4, coupled with δ34SSO4 are used to partition riverine sulfate sources in water. pH of water samples in study area ranged between 2.90 to 7.95 and ionic abundance was in order SO42- > Ca2+ > Mg2+ > HCO3- > Na+ > Cl- > K+ > NO3- > NH4+ > F-. Sulfate ion ranged between 9.29 to 5051.57 mg/L. δ34SSO4 ranged between -12.87 to 9.75 ‰ (V-CDT) and δ18OSO4 ranged between -17.32 to 22.36 ‰ (V- SMOW). δ18OH2O ranged between -7.91 to -3.94 ‰ (V- SMOW) and δDH2O ranged between -49.57 to -28.69 ‰ (V- SMOW). The difference between oxygen isotope compositions in SO42- and H2O (Δ 18OSO4-H2O) ranged from -11.26 to 28.96 ‰. Oxidation of sulfides contributed sulfur largely in rivers impacted by acid mine drainage (AMD) followed by evaporites weathering and dissolution in the study area. Evaporation and mineral dissolution play dominant roles in AMD impacted water. The results from study will help in defining measures for remediation of polluted rivers in the study area.
The changing relationship between precipitation efficiency and global precipitation
Authors: Sarkar Subhadip , Kuttippurath Jayanarayanan , Patel Vikas Kumar
Published: March 2024

Precipitation efficiency (PE) is the relationship between cloud condensation and precipitation that links the atmospheric circulation to the hydrological cycle. Definition and thus, estimates vary greatly due to the underlying microphysical dependencies of PE. It also quantifies the fraction of condensed water in clouds that falls as surface precipitation. Consequently, there is a dearth of knowledge about the sensitivity of PE to the global warming and its subsequent implications for climate change. Therefore, here, we estimate the global PE based on the surface precipitation and cloud water path1 , and quantify its role in the variability and changes in precipitation in the climate change context using the Moderate Resolution Imaging Spectroradiometer (MODIS) and Global Precipitation Measurement (GPM) observations for the period of 2001–2020. We find that the annul mean PE is very high in the tropics, including both the West Pacific and Indian Ocean Warm Pool. Other regions in the tropics, like Amazonia and Central Africa also show very high PE values. These regions also have very high surface precipitation. There is gradual decline in PE in the tropics in the last decade (2010–2020), which is consistent with the decreasing trend of precipitation there. Regions such as the warm pool, Northeast India and Amazonia show a decreasing pattern in both PE and precipitation in the past decade. This decline in both PE and precipitation in the tropics suggests that, a fraction of condensed water falls as precipitation decreases. On the other hand, there is notable rise in temperature in the tropics during the same period. However, the quantification of the sensitivity of PE to global warming on a regional scale is very critical.
Assessing similarity in continuous seismic cross-correlation functions using hierarchical clustering
Authors: Yates Alexander , Caudron Corentin , Lesage Philippe , Mordret Aurélien , Lecocq Thomas , Soubestre Jean
Published: March 2024

Passive seismic interferometry has become a popular technique towards monitoring subsurface activities in a variety of settings. This includes active volcanoes and geothermal fields spanning a large range of temperatures (25C to 250C) in Belgium and Iceland. The method depends on the relative stability of background seismic sources in order to make repeatable measurements of subsurface properties. Such stability is typically assessed by examining the similarity of cross-correlation functions through time. Thus, techniques that can better assess the temporal similarity of cross-correlation functions may aid in discriminating between real subsurface processes and artificial changes related variable seismic sources.In this work, we apply agglomerative hierarchical clustering to cross-correlation functions computed using seismic networks at volcanoes. These include Piton de la Fournaise volcano (La Réunion island) and Mt Ruapehu volcano (New Zealand). Clustering is then used to form groups of cross-correlation functions that share similar characteristics and also, unlike common similarity measures, the method does not require a defined reference period. At Piton de la Fournaise, we resolve distinct clusters that relate both to changes in the seismic source (volcanic tremor onset) and changes in the medium following volcanic eruptions. At Mt Ruapehu, we observe a consistency to cross-correlation functions computed in the frequency band of volcanic tremor, suggesting tremor could be useful as a repeatable seismic source. Our results demonstrate the potential of hierarchical clustering as a similarity measure for cross-correlation functions, suggesting it could be a useful step towards recognizing structure, or complex patterns, in seismic interferometry datasets. This can benefit both decisions in processing and interpretations of observed subsurface changes.
Examining surface water conditions over the past 250,000 years off the coast of Namibia: exploring the diverse impacts of Agulhas Leakage and Benguela Upwelling
Authors: Zarkogiannis Stergios , Frankel James , Rickaby Rosalind
Published: March 2024

The Southeast Atlantic Ocean plays a crucial role in the overall circulation of the world's oceans facilitating the transfer of heat and salt into the Atlantic and hosting the productive Benguela Upwelling System. Heat and salt are introduced to the South Atlantic via the Agulhas leakage and thus this leakage is considered important in controlling the strength of the Atlantic meridional overturning circulation (AMOC). In this study we reconstruct sea surface temperatures and salinities using coupled Mg/Ca and δ18Ο of Globigerina bulloides shells from site GeoB 1710-3 offshore Namibia. Our goal is to investigate the paleoceanography and surface ocean circulation patterns in this area during the late Pleistocene (0-250 ka). Furthermore, the chemical investigation is complemented by X-ray μCT measurements of the foraminifera specimens for dissolution assessment, aiding in the interpretation of a perplexing pattern in the G. bulloides shell weight record during the penultimate glaciation. 
Miocene to recent precipitation history of the central Atacama Desert as reconstructed from a clay pan record in the Coastal Cordillera, northern Chile. 
Authors: Wennrich Volker , Diederich-Leicher Julia , Scheidt Stephanie , Ritter Benedikt , Leicher Niklas , Albert Richard , Blanco-Arrue Barbara , Yogeshwar Pritam , Carballeira Rafael , Bao Roberto , Brill Dominik , Medialdea Alicia , Bartz Melanie , Campos Sepúlveda Eduardo , Dunai Tibor , Melles Martin
Published: March 2024

Hyperaridity is the major limiting factor of Earth-surface processes and biological activity in the Atacama Desert of northern Chile, one of the oldest and driest deserts on Earth. On geological timescales, however, the general aridity, which is thought to have onset during the Oligocene to Miocene, has been punctuated by distinct pluvial periods. Also nowadays sporadic but severe rainfall events, like during the flood in 2015, occur within the hyperarid core of the Atacama Desert. During the Miocene and Pliocene, such wetter conditions caused lake formation in parts of the Central Depression and Coastal Cordillera, but also amplified surface processes as well as changes in vegetation dynamics. Unfortunately, due to the limited number and heterogeneity of suitable paleoclimate archives, the long-term precipitation history of the central Atacama Desert and its drivers are still a matter of controversy.Here we present a first quasi-continuous (on time periods of 10-100 kyr) record of the Mid-Miocene to present paleoclimatic and environmental history of the central Atacama Desert obtained from an endorheic clay pan. Due to its location in the Coastal Cordillera, the investigated clay pan is assumed to have been decoupled from Andean ground and surface-water inflow, and thus to have recorded only local and regional precipitation variations on different timescales.The investigated 52 m-long sediment sequence exhibits significant changes in the sedimentological, geochemical paleontological, and mineralogical properties. Preliminary data from the recovered Mid-Miocene sediments imply permanent lacustrine conditions with alternating evaporation cycles that point to significantly different hydrological and/or climatic conditions in Coastal Cordillera than today. A major lithological shift, accompanied by a well-preserved paleosol, documents a significant local groundwater lowering, probably due to fault activation during the mid-Miocene. Subsequent high sedimentation of coarse-grained alluvial deposits indicates alternating periods of wetter than present precipitation, though still arid, conditions with episodic shallow lake phases during the Miocene. A distinct drop in the sedimentation rate and a synchronous transition to fine-grained distal alluvial deposits highlights a significant change in the moisture availability in the Coastal Cordillera during the Pliocene and Pleistocene, probably marking the final onset of hyperarid conditions in the central Atacama Desert.
Attributing low-frequency variations in ocean water mass redistribution during 2002-202
Authors: Deng Shanshan , Liu Yuxin , Zhang Wenxi , Hu Ange
Published: March 2024

Studying how ocean water mass is redistributed can help with a better understanding of the regional sea level change. This study investigates the roles of the different physical processes involved in low-frequency ocean water mass, including the sea level fingerprint and the dynamic ocean mass change, from regional to global scales over the period 2004-2021. Global water mass redistribution data from the GRACE and GRACE-FO satellites were used, as well as surface wind and sea surface temperature data from the ERA5 reanalysis. The sea-level equation is used to simulate the sea level fingerprint, and the maximum covariance analysis is used to extract possible signals of the wind-forcing and temperature-gradient-forcing ocean mass redistribution. The results show that the low-frequency ocean water mass is dominated by the long-term trend and the decadal-like fluctuation. Sea level fingerprint significantly contributes to the open ocean. Compared with temperature gradients, wind forcing plays a more important role in dynamic ocean mass redistribution. The wind-forcing dynamic processes significantly drive the anomalies near the North Indian Ocean, North Atlantic Ocean, South Pacific Ocean, and some marginal seas. After removing the sea level fingerprint and ocean dynamics, some non-negligible noise, located in seismic zones, was also found, suggesting the misestimation of seafloor deformation resulting from earthquakes in the GRACE/GRACE-FO data processing. These findings may improve our understanding of the long-term anomalies in regional and global sea levels.
Gauging the Sensitivity of GNSS for Resolving Vertical Land Motion Over Europe
Authors: Hohensinn Roland , Bock Yehuda
Published: March 2024

Through a parametric fit to daily vertical displacement time series from European Permanent GNSS stations, we conducted a statistical sensitivity analysis focusing on Vertical Land Motion (VLM) – specifically, station velocity (linear trend). We compared two independent corrections to raw observed displacements: non-tidal atmospheric, oceanic, and hydrological loading displacements, as well as a correction for common mode errors (CME). Our methodology involved selecting the most realistic stochastic models based on information criteria, analyzing GNSS-observed displacements and identifying discrepancies with loading model predictions. We also employed restricted maximum likelihood estimation (RMLE) to mitigate low-frequency noise biases, enhancing the reliability of velocity uncertainty estimates.Our results demonstrate that 1) an autoregressive, power-law, and white noise model combination is preferred for uncorrected GNSS VLM data, 2) when compared to the corrected cases, this model choice yields lower improvement rates in trend sensitivity than previously reported, and 3) RMLE reveals that for many stations, noise is optimally modeled by a combination of random-walk, flicker-noise, and white noise. We report median trend sensitivity and detection rates of about 0.5 mm/year (with best results for the CME-corrected case), approaching the GGOS goal of a 0.1 mm/year precision, crucial for sea level studies and other applications.
PACE-PAX validation campaign – validating PACE and supporting Earthcare
Authors: Cetinić Ivona , Knobelspiesse Kirk , Cairns Brian , Piñol Solé Monserrat
Published: March 2024

NASA’s Plankton, Aerosol, Clouds and ocean Ecosystems (PACE) Mission, scheduled to be launched in early 2024, will produce a variety of ocean color, aerosol, cloud and land surface data products from its three sensors. Some of these products will be created with established ‘heritage’ algorithms, and others are new, representing recent algorithm development and the unique measurement capability of the PACE sensors. A crucial part of the validation activities is the PACE Postlaunch Airborne eXperiment (PACE-PAX), that is planned to occur in September of 2024. This dedicated field campaign, due to its platform and instrumental setup, offers an opportunity to support not only PACE, but the EarthCARE mission as well, opening opportunities for validation, new collaborations, and development of new algorithms for both Earth science missions.