bluuebunny/crossref_metadata_2025 huggingface dataset:
GLONASS modernization: initial characterization of the first K2 spacecraft
Authors: Steigenberger Peter , Thoelert Steffen , Montenbruck Oliver
Published: March 2024

The current operational GLONASS constellation comprises three different types of spacecraft: GLONASS-M, GLONASS-M+ and GLONASS-K1. All satellites transmit legacy frequency division multiple access (FDMA) signals in the L1 and L2 frequency bands, where individual satellites make use of different transmit frequencies. For the M+ and K1 satellites, an L3 code division multiple access (CMDA) signal was added. CDMA signals are transmitted at the same frequency but with satellite-specific ranging codes.K2 is the latest generation of GLONASS adding CDMA signals in the L1 and L2 frequency bands. The first GLONASS-K2 satellite was launched in August 2023 and started signal transmission in early September 2023. Unfortunately, as of early 2024, no commercial GNSS receiver is able to track the L1 and L2 CDMA signals. Thus, measurements of a 30 m high-gain antenna are used for the characterization of these signals.The FDMA and CDMA signals of GLONASS-K2 are transmitted via dedicated antennas separated by about 1 m. The differential baseline vector between the phase centers of the two antennas is estimated from an ionosphere- and geometry-free linear combination of L1 and L2 FDMA and L3 CDMA signals observed by a global tracking network. Furthermore, the FDMA L1/L2 ionosphere-free phase center offsets (PCOs) w.r.t. the center of mass are estimated. Both types of estimates are compared to PCOs obtained from the FDMA and CDMA navigation message.The spacecraft body size of GLONASS-K2 is twice as large as the previous K1 generation. Due to the increased size and the more stretched shape of the satellite body, a proper modeling of the solar radiation pressure is of particular importance for precise orbit determination. Based on approximate dimensions of the satellite and default optical properties, an initial box-wing model is constructed. The performance of this model is evaluated by day boundary discontinuities, clock residuals, and the magnitude of estimated empirical orbit parameters. Finally, the latter quantities are used for an empirical tuning of the box-wing model.
Challenges in traffic emission modeling and their application
Authors: Matthias Volker
Published: March 2024

Atmospheric chemistry transport models (CTMs) are since long time an important tool for studying multi-phase chemical reactions, particle formation and deposition processes of numerous trace gases and primary particles emitted into the atmosphere. These models need emission and meteorological information as essential inputs. Emissions are more than just a static inventory, they have dynamical spatial and temporal components. Therefore, separate model systems are typically applied for calculating the CTM input data. Their development and comprehensive evaluation are essential for enabling progress in air quality modelling. Emission control politics, in addition, need well suited tools to assess the overall impact of often costly emission reduction measures beforehand.This contribution focuses on emission models for ground based transport, in particular for ship traffic and road traffic. While state-of-the-art ship emission models apply bottom-up approaches that are based on ship position data and technical ship characteristics, road traffic emission models cannot treat each vehicle individually. Nevertheless, road traffic activity data can also be combined with emission factors for certain vehicle types and emission standards. However, diurnal profiles and weekday dependencies are often not included in the activities. How highly resolved traffic activity data from mobile phones can be used was demonstrated during the lockdowns in the early phase of the COVID-19 pandemic. Google mobility data or Apple data was widely used to improve road traffic emission estimates in spring 2020.In the presentation, challenges and limitations of ground based traffic emission model systems are discussed. In addition, their power for improving air quality simulations as well as for constructing consistent future emission scenarios, that are essential for intelligent emission reduction policies, are illustrated.
Provenance Analysis of Zeus/Owl bronze Coins from Velia: A Comprehensive Study using ICP-MS and TIMS Techniques
Authors: Ercoles Isabella , Castorina Francesca , Nisi Stefano , Carbone Federico , Pardini Giacomo , Trincherini Pier Renato
Published: March 2024

The project focuses on a provenance study carried out on Zeus/Owl bronze coins, coming from the Greek colony of Velia in southern Italy, and dating back to the 3rd century BC. Chemical elemental composition and lead isotope analyses were carried out at the Laboratori Nazionali del Gran Sasso-INFN by using ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and TIMS (Thermal Ionization Mass Spectrometry) techniques. Lead isotope ratios of the coin samples were compared with data from various ore deposits in the main Mediterranean areas documented in existing literature. Additionally, the elemental composition was examined to establish distinctive geological characteristics aiding in identifying the provenance sources of the studied coins. The majority of the coins exhibited an isotope signature of the lead, that makes up the alloy, overlapping with multiple clusters in the Aegean Greece area (Syros, Kea, Antiparos, Serifos and Sifnos) and the Spain South-East area (Cartagena-Mazarron and Almeria). Six coins displayed an uncertain provenance, suggesting the possibility of mixing and/or metal recycling. Notably, one coin demonstrated overlap with both Spain South-East and Tuscany clusters, indicating a shared provenance probability. Regarding the results of the elemental analysis, the main elements that make up the coins alloy are copper, lead and tin. The Pb content ranges considerably from a minimum of 0.5% to a maximum of 24.9%, while the concentration of Cu ranges from a minimum of 73.3% to a maximum of 93.5% and that of Sn ranges between 1.7% and 10.3%. This information contributes to the reconstruction of historical trade routes, enhancing our understanding of the dynamics of metal supply and socio-economic relationships in Velia.Keywords: Provenance study; Isotopes; Ancient Coins; Ore Deposit; TIMS
Exploring the diversity of methods in the study of minerals: a case study on organic-rich shale in the Shahejie Formation, Bohai Bay Basin
Authors: Gao Bo , Xu Shang , Zhang Zhiyao , Zhao Tongxu
Published: March 2024

This study delves into the continental organic-rich shale of the Shahejie Formation in the Lijin Sag, Dongying Sag, Bohai Bay Basin, with a focus on exploring the diverse array of methods and approaches utilized to study minerals. By employing an assortment of analytical techniques, including XRD diffraction, scanning electron microscope observation, QEMSCAN scanning, organic matter type detection, TOC testing, and thermal maturity tests, we elucidate the material composition, lithofacies type, and lithofacies combination of the organic-rich shale. Moreover, our investigation incorporates comprehensive imaging logging, core scanning, thin section observation, SEM, CT scanning, FIB-SEM, porosity analysis, nuclear magnetic resonance, high-pressure mercury injection, and gas adsorption to characterize the pores and fractures of shale reservoirs at different scales. The controlling factors influencing the spatial development and evolution of shale reservoirs are thoroughly discussed. In addition, we conducted conventional pyrolysis and multi-temperature pyrolysis experiments to study the shale oil content in different occurrence states. This allowed us to clarify the oil-bearing properties and occurrence characteristics of the shale. Lastly, based on our research findings and the comprehensive evaluation of the oil-bearing capacity and production performance of wells with different productivity in the study area, we not only discuss the law of shale oil enrichment but also establish a model for shale oil enrichment. This study serves as an important contribution to understanding the diversity of methods employed in the study of minerals, particularly in the context of continental organic-rich shale reservoirs. It offers valuable insights for guiding regional shale oil exploration endeavors.
First results of the analysis of the input data series provided by the IAG technique services for the extension of xTRF202
Authors: Seitz Manuela , Bloßfeld Mathis , Glomsda Matthias , Angermann Detlef , Rudenko Sergei , Zeitlhöfler Julian
Published: March 2024

The latest realizations of the ITRS, specifically the ITRF2020, the JTRF2020 and the DTRF2020, have been computed using input data series provided by the IAG technique services IVS, ILRS, IGS and IDS. They cover the entire observation period of the individual techniques until the end of 2020. Since 1996, recalculations of the ITRF have been performed approximately every 3 to 6 years. The main reason for recalculation is to ensure a high accuracy of the ITRF for current applications. In particular, seismic events that occure after an ITRF release as well as the general increase of the ITRF extrapolation error with time are key factors that cause the increase of the ITRF uncertainty. To enhance the frequency of ITRS realizations and consequently improve the accuracy of the ITRF, the ITRS Product Center plans to calculate annual updates of the ITRF2020 starting in 2024. The IAG technique services will provide three additional years of analyzed observations (2021-2023) collected after the end of the ITRF2020 observation period in February 2024. As an ITRS Combination Center, at DGFI-TUM, we will analyze the data series w.r.t. discontinuities, post-seismic deformations and their consistency with the input data series provided for the ITRS 2020 realizations. Model changes performed in between by the individual technique services, e.g. new PCO (phase center offsets) for GNSS satellites, updated mean long-term range biases for SLR satellites or gravitational deformation models for some more VLBI antennas, are expected to have an impact on the relevant ITRF parameters (station coordinates, EOP and datum parameters). Its order of magnitude and the effect of possible inconsistencies on the DTRF solution need to be investigated. We will present the first results of our analyses and draw preliminary conclusions regarding the accuracy of a possible DTRF2020 extension.
Rapid Earth uplift in southeast Greenland driven by recent ice melt above low-viscosity upper mantle
Authors: Weerdesteijn Maaike F. M. , Conrad Clinton P.
Published: March 2024

Along the periphery of the Greenland ice sheet, Global Navigation Satellite System (GNSS) stations observe uplift of a few mm/yr, reflecting Earth’s response to past and contemporary changes in Greenland’s ice mass. On the coast of southeast Greenland, near the Kangerlussuaq glacier, GNSS stations show abnormally rapid ground uplift, faster than 10 mm/yr. Current earth deformation models, which employ a layered Earth structure, cannot explain such rapid uplift. Here we develop 3D regional models of uplift in response to deglaciation occurring over timescales corresponding to the last glacial cycle (past 1000s of years), the last millennium (past 100s of years), and recent rapid deglaciation (past 10s of years). These 3D models incorporate a track of low-viscosity upper mantle and thin lithosphere, consistent with the passage of Greenland over the Iceland plume during the past ~50 Myr. We find that the fastest ground uplift occurs where rapid deglaciation occurs above the low-viscosity plume track of the Iceland plume. This uplift reflects viscous deformation of the upper mantle, and is much larger than the (instantaneous) elastic deformation that also results from this deglaciation. Above the low-viscosity plume track, the uplift contribution is greatest for the most recent deglaciation (past decades), followed by the contribution from deglaciation during the last millennium. The combination of these viscous contributions can explain uplift observations of more than 10 mm/yr near the rapidly deglaciating Kangerlussuaq glacier, which lies above the Iceland plume track, and slower uplift in the surrounding areas. Rapid uplift observed to the south of the Kangerlussuaq glacier can be explained if the low-viscosity plume track extends farther southward beneath the Helheim glacier, which is also rapidly deglaciating. Such rapid viscous uplift from recent and local ice melt is not usually considered in glacial isostatic adjustment (GIA) models, but likely happened in the past in response to previous deglaciation. It will also become increasingly important in the future as deglaciation accelerates.
Firn Density Distribution and Annual Snow Water Equivalent Estimates from Ground Penetrating Radar
Authors: Patil Akash , Mayer Christoph , Braun Matthias
Published: March 2024

Abstract: Accurate estimation of glacier volume-to-mass conversion relies on a thorough understanding of firn density, both in-depth and over time. Ground-penetrating radar (GPR) serves as a suitable geophysical tool to trace internal reflection horizons (IRHs) and estimate the physical properties of different layers. Our goal is to characterize the IRHs as annual layers and ascertain the spatial firn density-depth profile in the accumulation zone of the Aletsch glacier.The process involves identifying IRHs from radargrams and iteratively selecting the annual layers by excluding unreasonable layer structures. For an accurate estimation of firn density distribution, it is necessary to derive the velocity-depth profile of electromagnetic waves within the firn zone. The common mid-point (CMP) method was applied to track the velocity distribution within the firn body. Additionally, a method was introduced to estimate the velocity-depth profile for longer GPR profiles by backtracking the calculated velocity from the CMP gather.To validate IRHs as annual firn layers, we utilized annual accumulation measurements at a nearby stake for Snow Water Equivalent (SWE) estimation. The resulting firn density-depth profile was compared to different firn densification models, considering regional meteorological information. This approach enables us to determine a reliable density-depth function for bulk SWE computations. The study also addresses uncertainties associated with selecting IRHs as annual layers and enhances the application of local volume-to-mass estimates.
Do beech and spruce change their carbon allocation under future environmental conditions? Lessons learned from a three-year growth chamber experiment. 
Authors: Gu Qiao-Lin , Baumgarten Manuela , Jakli Balint , Rammig Anja , Grams Thorsten , Hesse Benjamin
Published: March 2024

Plant carbon (C) allocation describes the distribution of carbon among different organs and processes and is sensitive to environmental conditions. As climate change proceeds, it will introduce additional uncertainties to the forest’s function as a crucial terrestrial carbon sink. Previous studies have explored the effect of single environmental variables on plant carbon allocation. Still, they cannot provide insights into the combined effects of changing environment in the future. To understand how European tree species will alter their C allocation after acclimating to the future environment, beech and spruce seedlings were grown in controlled environment facilities (CEFs) of different scenarios for three years. The scenarios represent the present condition of 1987 to 2016 (PC) and, in accordance with the IPCC scenarios, a mitigation scenario (RCP2.6) and a worst-case scenario (RCP8.5) of 2017 to 2100. This implies an increase in air temperature by approximately 1°C (RCP2.6) and 3°C (RCP8.5), an increase in CO2 concentration by approximately 30 ppm (RCP2.6) and 500 ppm (RCP8.5), and changes in other variables over the three years, including the irradiance, the relative humidity, and the O3 concentration. After three years of treatment, the plants were labeled with 13C-enriched CO2 for three days to understand the allocation and turnover of new photoassimilates. Both beech and spruce had greater biomass under RCP8.5 compared to RCP2.6 and PC, accompanied by enhanced allocation to belowground biomass. The concentration of non-structural carbohydrates (NSC) showed no significant difference across the scenarios, neither in leaves nor fine roots. Yet, the mean residence time of carbon (MRT) of the soil respiratory pool had shortened in the RCP scenarios in both species. Specifically for beech, a compartmental model showed an increased pool size of mobile carbon and confirmed the shortened MRT of the mobile carbon pool under RCP8.5. The unchanged NSC concentration in the sink organ with the shortened MRT has indicated a more rapid carbon turnover under both RCP scenarios accompanied by more substantial C allocation to the immediate respiration. Additionally, the fixed C was substantially invested in biomass growth, i.e., structural carbon, only under RCP8.5, which indicates that the doubled CO2 concentration has alleviated the environmental stress. In contrast, the minor increase in CO2 concentration under RCP2.6 had no such effect. We thus recommend that the relationship between C fixation and biomass growth should be interpreted more cautiously under changing environmental conditions in the future.  
A lacustrine sediment perspective on the seismic cycle in Southeast Tibet
Authors: lemot François , Sabatier Pierre , Chevalier Marie-Luce , Crouzet Christian , Rioual Patrick , Develle Anne-Lise , Fang Ziqi , Replumaz Anne
Published: March 2024

The Tibetan Plateau formation, resulting from the collision between India and Eurasia, is accompanied by significant seismic activity. Along its SE margin, the sinistral Xianshuihe fault is one of the most active faults in China. To understand the seismic cycle and estimate subsequent hazards, long-term records extending beyond historical archives are required. In Kangding's restraining bend, fault partitioning leads to seismic activity being distributed across four branches, exposing significant population and critical infrastructures to seismic hazards. To document the long-term patterns of fault activity, we identified seismically-triggered event deposits in three mountain lakes near the fault, using a multiproxy approach, including CT scanning, grain-size analysis, and XRF core scanning, associated with chronology based on palaeomagnetism, short-lived radionuclides, and radiocarbon ages. Our investigation across three sites (Yari Acuo, Yalatuo, Mugecuo) distributed over 30 km of the fault, revealed varying sensitivities to seismic events over the past ~300 years. Based on these different sensitivities to record earthquakes, this multi-site approach allowed us to relocate historical earthquakes based on sediment core evidence. However, the high frequency of events and the uncertainties in age models limit our ability to unambiguously attribute the oldest deposits to specific events. The recently retrieved 3.6 m-long core from Lake Yalatuo, on which we will apply similar analyses, appears more promising to reconstruct the long-term regional palaeoseismological record and discuss the Xianshuihe fault seismic cycle.
Towards a 2D model of Discrete Fracture Network with permeability and friction evolution for modeling fluid-induced seismicity 
Authors: Romanet Pierre , Scuderi Marco , Chaillat Stéphanie , Ampuero Jean-Paul , Cappa Frédéric
Published: March 2024

Numerical modeling of Discrete Fracture Networks (DFNs) is commonly used to assess the behavior and properties of hydraulic diffusion and seismicity in the Earth’s crust within a network of fractures and faults, and to study the hydromechanical evolution of fractured reservoirs stimulated by hydraulic injection and production. The modelling of such fractures is typically carried out under a quasi-static approximation, and occasionally accounting for elasto-dynamics in single-rupture studies that assume a slip-weakening friction law. In this work, we develop a 2D DFN model to simulate fluid-induced seismicity that couples hydraulic diffusion and slip governed by rate-and-state friction on multiple interacting faults. The main goal of this numerical model is to establish a connection between laboratory derived friction parameters and field observations, enabling the inference of the long-term evolution of fractured reservoirs and crustal fault systems undergoing multiple earthquakes and (slow) slip events induced by fluid pressure perturbations.In the model, the elastic interactions are computed with a boundary element method, accelerated by the hierarchical matrix method. We assessed the convergence of the method at fracture junctions and verified it does not create unphysical singularities. The use of rate-and-state friction makes it possible to model several seismic events over the injection duration.The simulations will be later used to fit measurements of permeability and friction collected in laboratory experiments, in-situ observations of fault slip and opening from fluid injection experiments at decametric scale, and finally, induced seismicity at reservoir scale.  
Be/9Be in Arctic Ocean Sediments: Another clue towards a fresh Arctic hypothesis
Authors: Ollive Agathe , Adolphi Florian , Geibert Walter , Matthiessen Jens , Lachner Johannes , Stübner Konstanze
Published: March 2024

Marine sediments provide invaluable records of past climate variations. However, dating these sediments with classical dating methods is challenging in the Arctic Ocean because of the lack of foraminifera, their poor preservation, and the extremely low sedimentation rates. Yet, understanding the history of the Arctic Ocean is of great importance for assessing its potential response to the current fast warming of these high latitudes.Recently, Geibert et al. (2021) proposed that during some glacial periods, the Arctic Ocean might have been filled with freshwater. This hypothesis, which has potentially far-reaching implications, can explain intervals of low 230Th-excess and low 10Be concentration in Arctic sediments but is strongly debated (Spielhagen et al., 2022; Hillaire-Marcel et al., 2022). This hypothesis posits that during these freshwater intervals, primary input fluxes originated from Arctic rivers rather than the North Atlantic.To test this theory, we assess the 10Be/9Be ratio in sediments that correspond to the freshwater intervals. Since the 10Be/9Be ratio differs systematically between North Atlantic and riverine waters, this proxy used as a water mass tracer can give novel insights into the Quaternary history of the Arctic Ocean. We discuss our results in the light of the hypothesis by Geibert et al. and evaluate the use of 10Be/9Be as a dating and correlation tool of Arctic Ocean sediments contributing to the ongoing chronostratigraphic investigations in the Arctic Ocean. Geibert, Walter, et al. "Glacial episodes of a freshwater Arctic Ocean covered by a thick ice shelf." Nature 590.7844 (2021): 97-102.Spielhagen, Robert F., et al. "No freshwater-filled glacial Arctic Ocean." Nature 602.7895 (2022): E1-E3.Hillaire‐Marcel, Claude, et al. "Challenging the hypothesis of an Arctic Ocean lake during recent glacial episodes." Journal of Quaternary Science 37.4 (2022): 559-567.
Rock magnetic anomaly caused by the pyritization linking to the gas hydrate dissociation off SW Taiwan
Authors: Huang Yin-Sheng , Horng Chorng-Shern , Su Chih-Chieh , Hsu Shu-Kun , Doo Wen-Bin , Lin Jing-Yi
Published: March 2024

      In the study, we present the rock magnetic property from three sediment cores collected by the R/V Marion Dufresne (MD) during the cruise MD214 off SW Taiwan, and two of these cores, MD18-3542 and MS18-3543, have collected shallow hydrate samples. Core site MD18-3542 is on the South Yuan-An East Ridge, where an unconformity covered by fine-silt sediments lies at ~5.5 m below the seafloor, and the core site MD18-3543 is close to the Good-Weather Ridge with a gas-related pockmark and authigenic carbonates near shallow strata. The other core MD18-3548 was obtained at a basin with relatively stable deposition settings to get the background information. Rock magnetic measurements, including magnetic susceptibility (MS) and hysteresis parameters, are used to describe the downcore variations of the magnetic features, while the Day Plot and XRD analysis are applied to classify and identify the dominance of core magnetic components. Both cores MD18-3542 and MD18-3543 show the attractive anomaly with dramatic value-drop in the records of MS and hysteresis parameters, and the feature looks absent in the core MD18-3548. Such signature may link to the pyritization caused by the gas hydrate dissociation. The dissociated methane with hydrogen sulfide trapped under the structures (an unconformity at site MD18-3542 and authigenic carbonates at site MD18-3543) would form an anoxic setting and activate the pyritization at shallow layers. Detrital magnetite would be gradually turned into authigenic iron sulfides, and thus could cause the attractive anomaly in the MS and hysteresis records.
Daily to decadal changes: Insights from a high resolution 10-year record of atmospheric carbon dioxide, observed from coastal Antarctica.
Authors: Squires Freya , Jones Anna , Phillips Tony , France James , Wullenweber Nellie , Weller Rolf
Published: March 2024

The Southern Ocean is the dominant marine sink for anthropogenic carbon, absorbing around 40% of carbon emitted since industrialisation, but it is a remote and challenging region to measure. Sparsity of observational data is the main cause of uncertainty in air-sea carbon flux in the Southern Ocean. Year-round observations of CO2 mixing ratios can aid understanding of air-sea flux in this critical region and provide valuable insight into how the carbon sink is changing over time as well as its seasonal and interannual variability.This work presents ten years of high frequency in situ carbon dioxide mixing ratios measured from two coastal Antarctic research stations; Halley, operated by the British Antarctic Survey, and the German research station, Neumayer. This data set provides a rare long-term measurement of CO2 in the Southern Ocean region, allowing annual growth rates, seasonal changes and interannual variability to be studied. The mean annual growth rate was calculated to be ~2.4 ppm year-1 between 2013 and 2022.The coastal location of these stations mean they are ideally placed to explore air-sea CO2 exchange in the Southern Ocean. Both the Halley and Neumayer records show short-term fluctuations in CO2 mixing ratios during the summer, with up to ~0.5 ppm decreases in CO2 over the course of a day, about one fifth of the average annual growth rate. Air mass trajectory analysis carried out using Hysplit with ERA5 meteorological data, suggests that these decreases in CO2 correspond to periods where the air sampled has spent time over the Southern Ocean, suggesting CO2 uptake has occurred. This work explores the possible drivers for the short-term variability in CO2 mixing ratios, focusing on the role of ocean uptake in the summer.
Stable-isotope probing identifies microorganisms actively degrading DMSP in anaerobic saltmarsh sediments
Authors: Eyice Özge , Hawthorne Susan , Tsola Stephania , Carrión Ornella , Todd Jonathan
Published: March 2024

Billions of tons of dimethylsulfoniopropionate (DMSP) are produced every year in marine and coastal ecosystems such as saltmarshes and estuaries. DMSP has far-reaching roles in global carbon and sulfur cycling, also as an osmotolerant and signalling molecule. Furthermore, the microbial degradation of DMSP contributes significantly to the formation of dimethylsulfide (DMS) and methanethiol (MT), other abundant organosulfur compounds with ecological significance. Particularly, in anaerobic sediments, microbial DMS and MT degradation leads to the formation of methane, a powerful greenhouse gas. However, research to date has predominantly focused on aerobic settings, revealing diverse groups of microbes and enzymes mediating DMSP degradation. DMSP concentrations in anaerobic ecosystems and microbial populations underlying DMSP breakdown have never been studied, prohibiting improvements in our understanding of global carbon and sulfur cycles. To address this key knowledge gap, we applied stable-isotope probing combined with 16S rRNA sequencing to identify the active DMSP-degraders in anaerobic saltmarsh sediments.We collected sediments from a 5-10 cm depth of Medway Saltmarshes (UK) using 3.5cm Perspex corers. We transferred the samples to the laboratory and measured in situ DMSP concentrations of 7.7 (±0.5) μmol g−1 wet sediment. In line with the in situ concentrations, we set up replicated incubations anaerobically with 8 μmol g−113C- and 12C-labelled DMSP, and applied stable-isotope probing combined with 16S rRNA sequencing.We observed immediate degradation of DMSP in the sediment incubations and DMS production, suggesting the existence of a resident microbial community actively carrying out this process. A total of 48 μmol/g 13C- or 12C-DMSP was amended and a total of 34 (±3.2) μmol/g DMS was produced in the incubations over 12 days.  DNA was extracted and ultracentrifugation was applied to separate heavy and light DNA fractions for downstream analysis. 16S rRNA sequencing of the fractions from 13C and 12C-labelled DNA demonstrated significant enrichment of the family Nitrincolaceae within the order Oceanospirillales in 13C-heavy fractions compared to 13C- light and 12C-heavy fractions (P
Tracking high-alpine snow mass evolution using signals of a superconducting gravimeter combined with snowpack modelling and stereo satellite imagery
Authors: Koch Franziska , Gascoin Simon , Achmüller Korbinian , Schattan Paul , Wetzel Karl-Friedrich , Rehm Till , Schulz Karsten , Voigt Christian
Published: March 2024

Monitoring the amount of snow, its spatiotemporal distribution as well as the onset and amount of snow-melt induced runoff generation are key challenges in alpine hydrology. Cryo-hydro-gravimetry is a non-invasive method of observing temporal gravity variations after the reduction of all other geophysical signals as the integral of all cryospheric and hydrological mass variations including snow accumulation and ablation. It has an accuracy of up to 9 decimals on a wide spectrum from high temporal resolution of up to 1 min to several years within footprints up to approx. 50 km². At the Zugspitze Geodynamic Observatory Germany (ZUGOG) with its worldwide unique installation of a superconducting gravimeter at a high-alpine summit (2.962 m a.s.l.), this method is applied for the first time on top of a well-instrumented, snow-dominated catchment. We use this instrumental setup in synthesis with in situ measured data, detailed physically-based snowpack modelling with Alpine3D as well as satellite-based snow depth maps derived by stereo photogrammetry. We will give an introduction into the novel sensor setup and will show first results, including the sensitivity of the integrative gravimetric signal regarding the spatially distributed snowpack and the cryo-hydro-gravimetric signal changes since 2019. The amount of the simulated snow water equivalent within the footprint of the gravimeter correlates well with the gravimetric signal (Pearson correlation coefficient r = 0.98). Based on the applied snowpack modelling approach including the snow depth maps for precipitation scaling, topography information as well as Newton’s Law of Gravitation, the gravimetric signal contribution and footprint can be described spatiotemporally over winter periods.
Developing High-Resolution Models for Forecasting Sea Surface Currents and Marine Effluent Dispersion
Authors: Petelin Boris , Ličer Matjaž , Vodopivec Martin , Čermelj Branko
Published: March 2024

The Gulf of Trieste is the northernmost part of the Mediterranean and the Adriatic Sea. It is home to lively shipping traffic, tourism, and fishing. The Gulf of Trieste is home to two of the most important ports on the Adriatic coast - Trieste and Koper. We have developed high-resolution operational numerical models for the operational prediction of the distribution of sea surface currents and the dispersion of wastewater from the sewage treatment plant into the sea:(1) Prediction of the distribution of surface currents in the Gulf of Trieste (northern Adriatic Sea) to complement measurements from four HF radars stationed in the Gulf of Trieste. The radar provides current measurements at 30-minute intervals, except during maintenance work and occasional technical faults. In some areas, there are also occasional outages and unreliable current measurements, so high-resolution current models are of additional benefit. The two-day hourly forecast of sea currents provided by our model is displayed on the website along with the HF radar measurements. The most typical user of the HF radar measurements is the Slovenian Maritime Administration, which is responsible for the safety of navigation, management of maritime traffic and maintenance of safety facilities and waterways. The results of our numerical model can provide reliable information on the direction and strength of sea currents, which helps ship operators to plan their routes more efficiently, reduce fuel consumption and emissions, increase shipping safety, and enable better control of oil spills.(2) Predicting the dispersion of wastewater from a wastewater treatment plant into the coastal sea. The Rižana wastewater treatment plant is located in the Gulf of Trieste, just upstream of the mouth of the Rižana river into the port of Koper. The results of the numerical model show whether the wastewater from the treatment plant enters protected areas or bathing waters. The results can help the relevant authorities to predict and prepare for potential pollution events, contribute to a better understanding of the processes in the coastal sea that control the transport, mixing and fate of pollutants, and show which marine areas are particularly vulnerable to pollution.The high-resolution numerical models for predicting surface currents and the dispersion of sewage in the Gulf of Trieste represent a significant advance in maritime safety and environmental management. This underlines the valuable role of advanced modeling in promoting sustainable maritime practices and protecting the fragile ecosystem of the northern Adriatic.
Dynamic response of the Mediterranean Sea surface circulation at various global warming levels: A multi-model approach
Authors: Parras-Berrocal Iván Manuel , Waldman Robin , Sevault Florence , Gonzalez Nicolas , Somot Samuel
Published: March 2024

Changes in the Mediterranean circulation patterns due to global warming may have strong socio-economic and environmental impacts. Here, we analyze the future evolution of the Mediterranean surface circulation under different levels of global warming (from 1°C to 4ºC) with respect to the preindustrial period. To this end, we use a set of 18 multi-decadal simulations (7 historical and 11 scenario projections) from a set of seven coupled regional climate system models of the Med-CORDEX initiative. For the first time, global warming levels are used to assess impacts of climate change on the Mediterranean Sea, allowing us to combine CMIP5 (RCP2.6, RCP4.5 and RCP8.5) and CMIP6 (SSP5-8.5) scenarios in a multi-model and ensemble approach. Most of the models show an accurate representation of the surface circulation in the historical period, although biases in the mean SSH and wind stress are observed. In terms of variability, we show that a minimum horizontal resolution of ~11 km is necessary to reproduce the dominant eddy-driven dynamics. The circulation is mainly driven by geostrophic currents, while Ekman currents are about one order of magnitude smaller than the mass-driven circulation. We find a linear relationship between the mean absolute dynamical response and the global warming level. The mean surface circulation shows the strongest response in the Balearic Sea, the Gulf of Lions, the southern Adriatic and along the Mid-Mediterranean Jet. Furthermore, our results suggest that future changes in the Mediterranean circulation variability will be primarily associated with a general increase of high-frequency processes (eddies), while the seasonal cycle and interannual variability will play a secondary role.
Augmenting Tsunami Detection with a Ship-based GNSS Network
Authors: Foster James , Ericksen Todd , Thomas Bruce , Avery Jonathan , Xie Yuke , Knogl Robin
Published: March 2024

We demonstrated the potential for ship-based GNSS systems to contribute to tsunami warning with a pilot network of 10 ships – 8 commercial and 2 research vessels - equipped with a tsunami detection package that included a geodetic-grade GNSS antenna and receiver, and a satellite internet communication system. The ships we instrumented operated throughout the Pacific, and transmitted real-time precise positions to our shore server from 2015-2018. This data set is used to examine the performance that an operational system would be able to expect if employed for tsunami detection. The estimated accuracy for our real-time vertical position solutions is 5.6 cm, commensurate with the advertised accuracy of the positioning service we employed. This indicates it is plausible to expect to observe the sea surface perturbation of a potentially dangerous tsunami with open ocean wave amplitude of more than 10 cm.  Significant numbers of long period (10s of minutes) excursions, however, appear in the data in the absence of actual tsunami. The similarity of these excursions with the signals expected from a tsunami would result in a high rate of false positive detections if the ship data were used to independently identify tsunami events. A significant number of these were associated with ships changing speed as they were approaching or leaving port. A simple masking strategy based on the ship’s speed reduces the number of these artifacts by 48%. The rate of false positive detections can be reduced to negligible levels by treating the network as an ensemble detection system and examining the data from 4 or more ships together. The density of ships in the open oceans are shown to be well matched to the source regions of historical fatal tsunamis, confirming this approach could provide valuable additional data to tsunami warning centers. We suggest that a network of ships, equipped with geodetic GNSS packages, based on a voluntary participation model, and leveraging the results from our pilot project would provide a valuable low-cost augmentation to the current tsunami detection systems. Furthermore, extended tsunami detection capability from this proposed ship network is possible by leveraging the ability of dual frequency GNSS to detect ionospheric perturbations. Tracking perturbations in the total electron count along the ray paths between each ship and each GNSS satellite provides multiple additional time series that have demonstrated capability to detect the ionospheric signals induced by open ocean tsunamis.  Implementing these data streams would therefore expand the effective monitoring zone of each ship in the network from a single tide-gauge-like point to multiple observations within a circle with radius more than 500 km.
Atmospheric excitation of the annual wobble over the 21st-century from CMIP6 predictions under different scenarios
Authors: Böhm Sigrid , Strümpf Anne , Salstein David
Published: March 2024

The annual wobble is the second distinct feature of polar motion after the Chandler wobble. It is a seasonally forced oscillation driven mainly by significant pressure differences between boreal winter and summer over Siberia. In this study, we investigate the future evolution of the annual wobble amplitude from 21st-century model projections of atmospheric pressure and wind velocities. The model variables are provided within the Coupled Model Intercomparison Project Phase 6 (CMIP6) for different scenarios that simulate possible future anthropogenic drivers of climate change. We use the simulations of 11 models for five such scenarios, which range from very mild to quite extreme future climate changes. The 21st-century simulations span 85 years, from 2015 to 2100. Our analysis focuses on the temporal evolution of the amplitude of the annual oscillation in equatorial atmospheric angular momentum functions. More intense scenarios involving more substantial global warming show an increase in the magnitude of the annual wobble towards the end of the century. More extreme annual pressure anomalies over the North Asian landmass probably cause the rising amplitudes.
Metamorphic P–T-t path and tectonic implications of the eclogite from Changning–Menglian orogenic belt, southeastern Tibetan Plateau
Authors: Zhou Ying , Cheng Hao , Peng Zhimin , Fu Yuzhen , Du Kaiyang
Published: March 2024

Understanding the relationship between ultra-high-pressure (UHP) metamorphic rocks and their surrounding country rocks is crucial for interpreting the tectono-metamorphic dynamics within orogenic belts. This study focuses on the Changning–Menglian orogenic belt in Southeast Tibet to delineate the subduction history of the Paleo-Tethys Ocean. We integrate garnet Sm–Nd and Lu–Hf dating, rutile/zircon U–Pb geochronology, phase equilibria modeling, and thermobarometry to examine high-pressure eclogites and surrounding metasediments. Pseudosection modeling and conventional thermobarometry suggest a clockwise pressure-temperature (P–T) path for the eclogite, from ~1.4 GPa/~505–530 °C to ~2.4–2.8 GPa/~600–640 °C, followed by decompression to
Verification of susceptibility and density relationship from 3D joint inversion of airborne magnetic and gravity data in northern Victoria Land, East Antarctica, with petrophysical measurements
Authors: Lowe Maximilian , Jordan Tom , Moorkamp Max , Ebbing Jörg , Koglin Nikola , Ruppel Antonia , Green Chris , Liebsch Jonas , Ginga Mikhail , Larter Robert
Published: March 2024

Subglacial geology remains largely unknowns in Antarctica. Direct geological samples are limited to ice free regions along the coast, high mountain ranges or isolated nunataks, while the origin of geological material transported by glaciers themselves is often ambiguous. 3D singular and joint inversions of airborne gravity and magnetic data recovers subsurface density and susceptibility distribution. The relationship between both inverted petrophysical quantities provide crucial insight for subglacial geology and rock provinces interpretations. Validation of indirect derived subglacial geology models are critical but very challenging in Antarctica due to the sparsity of rock samples.We present 324 new density and susceptibility measurements on rock samples from Northern Victory Land, East Antarctica. 251 samples have been measured at the National Polar Sample Archive (NAPA) from the Federal Institute for Geosciences and Natural Resources (BGR) in Berlin-Spandau, Germany and additional 73 samples were measured at the BGR in Hannover, Germany. We use the petrophysical measurements to validate our recent regional scale 3D joint inversion model of the Wilkes Subglacial Basin and the Transantarctic Mountains. Furthermore, we validate inversion results on a local scale of singular magnetic inversion based on high resolution airborne magnetic data with a flight line spacing of 500m in the Mesa Range.We demonstrate that we can provide reliable discrimination between Ferrar Dolerites, Kirkpatrick Basalt and Granite Harbour intrusion rocks based on our local inversion model and that the recovered susceptibilities agree with those measured at rock samples from the study area. Furthermore, we show that regional scale inversion model of gravity and susceptibility distribution agrees for samples of the dominant crustal rock types. However, densities of small-scale dense intrusion bodies like Ferrar Dolerites are underestimated by the regional scale inversion, while the susceptibility range is correctly recovered.Constraining subglacial geology with joint inversion of airborne potential field data is heavily depended on the resolution of the airborne survey, flight line coverage, the inversion scale, and the scale of the target feature. Regional scale inversion is adequate for large scale geological heterogeneities, which underestimate petrophysical quantities for small scale structures, while local scale inversions are able to resolve such structures but are more computational demanding and in the case of Antarctica lack ultra-high resolution airborne gravity data with a line spacing below 1000 – 500m.
A Statistical and Multiscale study of Kelvin-Helmholtz events under different IMF orientations 
Authors: Settino Adriana , Nakamura Rumi , Khotyaintsev Yuri , Graham Daniel B. , Blasl Kevin-Alexander , Nakamura Takuma , Perrone Denise
Published: March 2024

The Kelvin-Helmholtz instability (KHI) is a shear-driven phenomenon frequently observed at the Earth's low-latitude magnetopause when the velocity shear is super Alfvénic. KHI represents a way for plasmas to give rise to a turbulent scenario and to convert the energy due to the large-scale motion of the shear flow into heat. Indeed, the evolution of the KHI is characterized by the nonlinear coupling of different modes, which tends to generate smaller and smaller vortices along the shear layer. Both kinetic simulations and in situ measurements, focusing on the kinetic effects during the nonlinear phase of the instability, have shown the generation of strong current sheets between well-developed vortices, and temperature anisotropy and agyrotropy at both ion and electron scales, in accordance with the multi-scale nature of the phenomenon.Moreover, KHI is thought to play a crucial role in the transport of solar wind plasma into the magnetosphere and to efficiently contribute to the formation of the low latitude boundary layer. Although the instability threshold is equally satisfied during both northward and southward interplanetary magnetic field (IMF) conditions, in-situ measurements show that KHI privileges the northward orientation. We investigate this different behavior by analyzing the kinetic features at both boundaries and inside the KH structures. Thus, we statistically investigate several KHI crossings observed by the Magnetospheric Multiscale mission for different IMF orientations. Our statistical study can provide a better understanding about the global dynamics of the near Earth's environment and gives an important contribution to the solar wind-magnetosphere coupling mechanism.