bluuebunny/crossref_metadata_2025 huggingface dataset:
An operational geomagnetic baseline derivation for ground magnetometer data located in mid-latitudinal regions
Authors: Haberle Veronika , Marchaudon Aurélie , Chambodut Aude , Blelly Pierre-Louis
Published: March 2024

As a direct response to the increasing dependency on technological systems, the need for operational now- and forecasting of space weather events has been rising within the past decades.In order to monitor these events and their impacts, ground magnetic field data has proven to be a long-lasting and powerful source of information. Especially for the determination of the intensity and strength of solar forcing events, the derivation of geomagnetic baselines that extract the solar forcing portion from the rest of the superposing sources within geomagnetic field signals are of importance.In this work, we present a derivation method for determining the geomagnetic baseline for magnetic field data recorded at mid-latitudes. The contributing sources include the secular variation and the day-to-day variability, enabling the extraction of solar forcing contributions accurately. The derivation method is based on standard algorithms and does not need a-priori information other than the geomagnetic field measurements themselves. This enables the production of the baseline in near-real time and is thus suitable for operational purposes.The deployment of the introduced baseline allows for the operational identification of solar forcing intensities and may also be used for derivation of magnetic indices that use magnetic field data from mid-latitudinal observatories.
Exploring the Depths: 3D Modeling of Ukraine's Caves through Terrestrial Laser Scanning and Digital Photogrammetry
Authors: Oliinyk Mariia , Bubniak Ihor , Bubniak Andrij , Shylo Yevhenii , Vivat Anatolii , Mandzuk Valerii , Marko Taras
Published: March 2024

This study presents a comprehensive exploration of Mlynky Cave in Ternopil Region and Medova Cave in Lviv, Ukraine, utilizing advanced geospatial technologies for 3D modeling. In the investigation of Mlynky Cave located in the Ternopil region, terrestrial laser scanning and digital photogrammetry techniques were employed. Concurrently, for the exploration of Medova Cave situated in the city of Lviv and renowned as a unique tourist attraction, a combination of terrestrial laser scanning and manual scanning using the Stonex X120 handheld laser scanner was implemented.The application of terrestrial laser scanning and digital photogrammetry to Mlynky Cave facilitated the capture of high-resolution point clouds, resulting in a detailed three-dimensional representation of the cave's interior. The generated 3D model offers an immersive and navigable experience, allowing for remote exploration and analysis.In contrast, the exploration of Medova Cave, being a distinctive tourist landmark in Lviv, involved a dual scanning approach. Terrestrial laser scanning contributed to the overall mapping of the cave, while the Stonex X120 handheld laser scanner was specifically employed for targeted and detailed scanning of intricate features. This combination of technologies resulted in a holistic 3D model that preserves the unique geological formations and historical significance of Medova Cave.The findings from this research highlight the effectiveness of integrating various scanning methodologies, including terrestrial laser scanning and manual scanning with devices like the Stonex X120. The comprehensive 3D models not only contribute to scientific research and geological analysis but also serve as valuable tools for conservation efforts and educational purposes.This study sets a precedent for the application of advanced scanning techniques in cave exploration, showcasing the adaptability of technology in addressing the diverse challenges encountered during fieldwork. As the boundaries of geospatial technology in subterranean environments continue to expand, this research contributes to the evolving methodologies in cave exploration, emphasizing the importance of a multi-faceted approach to documentation and preservation.
Legacy IODP Cores Data in the Era of Big Data
Authors: John Cédric M.
Published: March 2024

Core data is pivotal for understanding our planet’s past, present, and future. Despite this richness, extracting meaningful insights from core description poses significant challenges due to the inherent complexity and variability of the data, the amount of existing material, and the subjectivity of the interpreter. IODP (and the preceding programs) offers a rich, well labelled source of core images that can be used in machine learning and deep learning.Focusing largely (but not exclusively) on carbonate rocks, characterized by their heterogeneity at all observational scales, I will discuss how my research group and I have pioneered the application of deep-learning computer vision to geological core interpretation. This technology transcends the traditional, tedious manual interpretations of cores, offering a rapid, and often more accurate, alternative for delineating depositional environments and sequence stratigraphy. Convolutional neural networks (CNNs) form the backbone of our approach, enabling us to process core data with unprecedented efficiency. I will show that these sophisticated models, when correctly trained and fed with substantial datasets, serve as invaluable tools for geologists, outpacing conventional methods in speed without compromising on precision.Our early work was centred on transfer learning, an AI approach that adapts pre-existing models to new data. I will show that this remains one of the best way to train classification algorithms for geological dataset. But we also worked on generative algorithms that fill gaps in our sampling of core imagery: for instance, we use Generative Adversarial Networks (GANs) to transform the resistivity images from formation micro scanners into representations mirroring actual core photographs, thus enhancing the interpretability for geologists irrespective of their background in downhole tools.We tackle the often-limiting factor of dataset size in two ways. First, we recourse to generative AI to oversample our training set. Second, we also explore semi-supervised learning techniques.  I will demonstrate that we successfully train models on core deformation images from IODP with minimal labelled data, achieving accuracy on par with, if not exceeding, that of transfer learning models.None of our achievements would have been possible without the recourse to IODP data. Hence, this presentation serves as a clear illustration of the value of legacy IODP data for future geoscientists.
Genesis and Tectonic Setting of Yanshanian Magmatic Rocks in the Northern Margin of South China Sea
Authors: lu fanrong , zhao junfeng
Published: March 2024

  Yanshanian magmatic rocks are widely distributed in the northern margin of the South China Sea and the continental margin of South China. These magmatic rocks are generally believed to have been formed by the subduction of the Paleo-Pacific plate to the South China Plate from Late Jurassic to Early Cretaceous. Due to the small number of wells drilled to the basement, most predecessors have studied on the distribution range, origin and tectonic setting of Yanshanian magmatic rocks by geophysical means(magnetic anomalies and seismic data). At present, The reported ages of basement magmatic rocks in the Pearl River Mouth Basin are mainly concentrated in Zhu 1 Depression and Panyu Low Uplift, and there is no petrological evidence in other regions.Baiyun Depression, as the largest hydrocarbon generating depression in the Pearl River Mouth Basin, has important oil and gas significance. In order to better define the spatial and temporal distribution of Yanshanian magmatic rocks, nearly 30 basement drilling samples in the periphery of Baiyun Depression and 8 onshore outcrop samples were collected. The genesis and tectonic significance of Yanshanian magmatic rocks are discussed through 76 thin sections, 7 U-Pb zircons dating, 26 major elements analysis, 16 trace elements analysis and 4 Sr-Nd-Pb isotope analysis.The results show that the magmatic rocks in the study area are concentrated in the J3-K1 and mainly developed S-type granite. These magmatic rocks are basically derived from the crust, and a few magmatic rocks or a small amount of mantle-derived materials are mixed in. The trace element discrimination diagram indicates that all samples belong to volcanic island arc type granite. The distribution curve of rare earth elements shows that light rare earth elements are enriched and heavy rare earth elements are low and stable.According to the above results, these magmatic rocks are part of the NE-trending continental margin magmatic arc formed by subduction and accretion of the paleo-Pacific plate to the South China Plate during the Yanshanian.Combined with the previous research results, it is believed that the extensional action caused by subduction and retreat of the Paleo-Pacific plate migrated to the ocean direction in the late stage of tensile rupture, and magmatism also migrated to the ocean, so the intrusion time of the magmatic rocks from continental to marine along the NW-SE direction gradually became late.This study adds important petrological evidence to clarify the genesis and tectonic setting of Yanshanian magmatic rocks in the northern margin of the South China Sea and the South China continent, and also has important application value for oil and gas exploration of buried hills in the Pearl River Mouth Basin.
Paleoarchean volcanic stratigraphy and geochemistry of the mafic-ultramafic Kromberg Formation type-section, Barberton greenstone belt, South Africa.
Authors: Grosch Eugene , Ndlela Sibu , Murphy David , McLoughlin Nicola , Trubac Jakub , Slama Jiri
Published: March 2024

In this study, the c. 3.334 Ga Kromberg Formation of the Onverwacht Group, in the south-eastern limb of the Onverwacht Anticline in the Barberton greenstone belt (South Africa) is investigated. Various geodynamic models have been proposed for the evolution of the Kromberg Formation, but detailed geochemical constraints on the mafic-ultramafic sequence are sparse. The objectives are to constrain the Paleoarchean mantle source characteristics and geodynamic setting for the Kromberg mafic-ultramafic rocks, placed in the context of recent high-resolution field mapping data. To study the protolith volcanic rocks, sampling has been conducted to avoid areas affected by deformation-related alteration. In addition, screening for alteration due to Archean seawater silicification has also been conducted. In conjunction with major, trace and rare earth element data, this study presents the first whole-rock Lu-Hf isotope analyses of mafic-ultramafic rocks of the Paleoarchean Kromberg Formation type-section in the Barberton greenstone belt (Grosch et al., 2022). Three compositionally distinct volcanic rock types are identified namely Group 1 metabasalts, Group 2 metabasalts and komatiitic metabasalts. The geochemistry of these rock types will be presented, and a possible geodynamic setting on the early Earth will be explored.  Grosch, E.G., Ndlela S., Murphy D., McLoughlin N., Trubac J., Slama J., (2022) Geochemistry of mafic-ultramafic rocks of the 3.33 Ga Kromberg type-section, Barberton greenstone belt, South Africa: Implications for early Earth geodynamic processes. Chemical Geology 605, 120947
Enhancing debris flow warning through seismic feature selection and machine learning model comparison
Authors: Zhou Qi , turowski Jens , Tang Hui , Hibert Clément , Chmiel Małgorzata , Walter Fabian , Dietze Michael
Published: March 2024

Machine learning can improve the accuracy of detecting mass movements in seismic signals and extend early warning times. However, we lack a profound understanding of the limitations of different machine learning methods and the most effective seismic features especially for the identifcation of debris flows. This contribution explores the importance of seismic features with Random Forest and XGBoost models. We find that a widely used approach based on more than seventy seismic features, including waveform, spectrum, spectrogram, and network metrics features, suffers from redundant input information. Our results show that six seismic features are sufficient to perform binary debris flow classification with equivalent or even better results., e.g., the Random Forest and XGBoost models achieve improvements over the benchmark of 0.09% and 1.10%, respectively, when validated on the ILL12 station. Considering models that aim to capture patterns in sequential data rather than information in the current time window, using the Long Short-Term Memory algorithm does not improve the binary classification performance over Random Forest and XGBoost models. However, in the early warning context, the Long Short-Term Memory model performs better and more consistently detects the initiation of debris flows. Our proposed framework simplifies seismic signal-driven early warning for debris flows and provides a proper workflow that can be used for detecting also other mass movements.
Summer fresh layers and winter mixed layers in the western Subpolar Gyre
Authors: de Jong Femke , Fried Nora
Published: March 2024

The strength of the Atlantic Meridional Overturning Circulation has been tied to deep convection in the subpolar North Atlantic. The depth of convection in winter, and the density of its product, depends on the balance between the water column stratification at the end of summer and the buoyancy removed through cooling in winter. As climate change progresses, ocean stratification is expected to increase as a result of warming and increasing fluxes of freshwater from the Arctic and Greenland, which in turn may weaken convection. Recently, a large freshwater anomaly has been seen to go round the Subpolar Gyre and has been speculated to increase stratification to the point where it inhibited convection in the Irminger Sea in 2019. However, less is known about near surface salinity in other years.Both the extent of the upper ocean summer fresh layer and the winter mixed layers are investigated using Argo profiles and gridded salinity products. Particularly the westernmost basins of the North Atlantic Subpolar Gyre are characterized by a strong seasonal cycle in near surface salinity. Fresh layers of around 50 m depth form over spring and summer and are diluted through mixing with deeper, more saline waters in winter. Larger fresh anomalies are seen in recent years, but Argo profiles show that this upper ocean freshwater can still be mixed over the water column if winter cooling is strong enough. This diminishes the fresh signal in amplitude, while spreading it over a much thicker layer. In the Labrador Sea and south of Greenland this can be seen in mixed layers over 1000 m deep, but even in the Irminger Sea fresh mixed layers down to 800 m were recorded in the winter of 2021-2022. Concomitantly, the western Subpolar Gyre has exhibited a freshening of the upper to intermediate water column that may partly be related to this spreading of freshwater over the water column. Documenting the strength and variability of the near surface summer fresh layer, and the extent to which it can be incorporated into winter mixed layers or not, will help project how deep convection may transition to a less frequent or weaker state in the future.
Unravelling the spatial structure of regular environmental spatial patterns
Authors: Kästner Karl , van de Vijsel Roeland C. , Caviedes Voullieme Daniel , Hinz Christoph
Published: March 2024

Spatial patterns where patches of high biomass alternate with bare ground occur in many resource-limited ecosystems. Especially fascinating are regular patterns, which are self-similar at a lag distance corresponding to the typical distance between patches. Regular patterns are understood to form autogenously through self-organization, which can be generated with deterministic reaction-diffusion models. Such models generate highly regular patterns, which repeat at the characteristic wavelength and are therefore periodic. Natural patterns do not repeat, as they are noisy and as the patch size and spacing vary. Natural patterns are therefore usually perceived as perturbed periodic patterns. However, the self-similarity of natural patterns decreases at longer lag distances, which indicates that their spatial structure is not a perturbed periodic structure originating through deterministic processes. Here, we provide an overview of our recent work on the spatial structure and formation of natural environmental spatial patterns as a basis for discussion: First, we develop a statistical periodicity test and compile a large dataset of more than 10,000 regular environmental spatial patterns. We find that neither isotropic (spotted) nor anisotropic (banded) patterns are periodic. Instead, we find that their spatial structure can be well described as random fields originating through stochastic processes. Second, we recognize the regularity as a gradually varying property, rather than a dichotomous property of being periodic or not. We develop a method for quantifying the regularity and apply it in a metastudy to a set of natural and model-generated patterns found in the literature. We find that patterns generated with deterministic reaction-diffusion models do not well reproduce the spatial structure of environmental spatial structure, as they are too regular. Third, we develop an understanding of pattern formation through stochastic reaction-diffusion processes, which incorporate random environmental heterogeneities. We find that regular patterns form through filtering of the environmental heterogeneities and identify stochastic processes which reproduce both isotropic and anisotropic patterns.
Rebuilding Lives on Lava: The Dynamic Forces Shaping Resettlement in Post-Eruption Goma 
Authors: Mafuko Nyandwi Blaise , Mani Lara
Published: March 2024

Crises and disasters are good opportunities for acquiring valuable insights and evolving toward the improvement of disaster recovery and resilience. Understanding the ability of a community to adapt and recover from the impacts of volcanic eruptions can significantly inform the effectiveness of future mitigation initiatives. This study analyses the aftermath of the 2021 Nyiragongo eruption in Goma (East DR Congo), exploring the dynamic forces shaping the decision of resettling on recent lava flows. In addition, it describes the affected population's self-initiatives in rebuilding their lives on recent lava flows. Focused on the recovery phase, this evaluation centres on key aspects of affected population resilience, specifically the individual strategies employed in self-housing reconstruction, water and power self-supply, and the community transformation of lava-impacted areas into green spaces. This study uses a multi-approach method, combining a large-scale survey (approximately 850 households), 20 interviews, and 4 focus groups.
Preliminary results indicate that the population exhibited adaptability, employing unconventional methods and using local and reused materials to rebuild their homes. Several households have developed a traditional composting system to foster the rapid development of soil on recent lava flows. Vegetable gardens and green spaces are beginning to appear 2 years after the eruption. At the community level, the population have set up a system of mutual aid to transform their environment and developed a community solar panel systems to light streets.
This research contributes to the broader discourse on disaster resilience, offering insights into the adaptive capacities of communities facing extreme challenges in the Global South. It can contribute to improving risk mitigation by taking into account positive local adaptive initiatives in the wake of crises in the Global South.
Monsoon Break over the South China Sea during Summer: Statistical Features and Associated Atmospheric Anomalies
Authors: Bi Minghao , Xu Ke , Lu Riyu
Published: March 2024

This study identifies break events of the South China Sea (SCS) summer monsoon (SCSSM) based on 42 years of data from 1979 to 2020, and investigates their statistical characteristics and associated atmospheric anomalies. A total of 214 break events are identified by examining the convection evolution during each monsoon season. It is found that most events occur between June and September and show a roughly even distribution. Short-lived events (3–7 days) are more frequent, accounting for about two thirds of total events, with the residual one third for long-lived events (8–24 days).The SCSSM break is featured by drastic variations in various atmospheric variables. Particularly, the convection and precipitation change from anomalous enhancement in adjoining periods to a substantial suppression during the break, with the differences being more than 60 W m−2 for outgoing longwave radiation (OLR) and 10 mm d−1 for precipitation. This convection/precipitation suppression is accompanied by an anomalous anticyclone in the lower troposphere, corresponding to a remarkable westward retreat of the monsoon trough from the Philippine Sea to the Indochina Peninsula, which reduces the transportation of water vapor into the SCS. Besides, the pseudo-equivalent potential temperature (θse) declines sharply, mainly attributable to the local specific humidity reduction caused by downward dry advection. Furthermore, it is found that the suppressed convection and anomalous anticyclone responsible for the monsoon break form near the equatorial western Pacific and then propagate northwestward to the SCS.
New perspectives and challenges on geodetic volcano monitoring using InSAR and last generation interpretation tools
Authors: Fernandez Jose , Camacho Antonio G.
Published: March 2024

Recent developments in InSAR (Interferometric Synthetic Aperture Radar) during the past decades allow to obtain high-precision, high-resolution ground deformation data with a broad spatio-temporal coverage. These large new datasets offer comprehensive insights into the deformation field and its time-evolution. Unfortunately, these new data sets cannot be fully exploited using the classical approaches for interpretation. In particular if we look for the most detailed estimation of the processes occurring in geologically active areas. Normally these classical approaches assume a priori geometries (e.g., point sources, disks, prolate or oblate spheroids, etc.) and nature of the source, and invert separately for the different sources when more than one is considered. Also, many time-series deformations in active regions are characterized by complicated patterns of ground deformation resulting from multiple natural and anthropogenic sources. In response to these challenges, we consider a new interpretation methodology which employs a combination of 3-D arbitrary sources for pressure and dislocations (including strike-slip, dip-slip, and tensile) simultaneously. This approach does not assume any a priori hypotheses regarding the deformation source’s number, nature, shape or location, providing deformation sources as 3D cell aggregations for which the inversion process automatically assigns a source type, magnitude values (MPa for pressure and cm for dislocations), position and orientation (angles of dislocation planes). The methodology inverts simultaneously ascending and descending LOS displacement time series data from InSAR, assuming the possible existence of offset values in the data sets. We show, as a way of example, a summary of the obtained results using last generation InSAR observation techniques and the new interpretation modeling to study the recent volcanic unrest and eruption in La Palma, Canary Islands, showing the obtained results.
Swath altimetry simulations with Radarspy, in preparation of Copernicus mission Sentinel-3 Next Generation - Topography
Authors: Yu Louise , Boy François , Desroches Damien , Bohe Alejandro
Published: March 2024

We wish to present the CNES contribution to the Sentinel-3 Next Generation - Topography (S3NG-T) project. In the wake of the SWOT mission, which pioneered the use of SAR interferometry for surface water altimetry, ESA is considering using this new approach for the successor to its current operational mission Sentinel-3 (S3), S3NG. Such so-called “swath altimetry” enables the access to two-dimensional features on water surfaces, much more directly than traditional Nadir altimetry (such as that used aboard S3) does, but it must also stand the test of accuracy requirements.Scheduled to take flight in 2033, the altimetry component of S3NG, called S3NG-T, is wrapping up its development phase B1 wherein two consortia designed their proposal of a swath altimetry mission, and during which SWOT’s very promising first data released. A Mission Gate Review in early 2024 should lead to the definitive decision whether to adopt this new measurement technique for S3NG-T or not. Rich with the heritage of their contribution to SWOT and convinced of the potential of swath altimetry, the CNES teams bring a technical expertise to the S3NG table.As such, we developed evolutions for Radarspy, our in-house simulator of swath altimeter data, in order to assess S3NG’s performances over oceans and inland waters. The swath altimetry instrument aboard S3NG-T, called SAOOH, differs from SWOT’s instrument mainly in its 3-meter baseline, its multiple receptors (four per swath – left or right – in order to flatten the gain pattern), and its interleaved observation pattern, where bursts of 128 Radar pulses are sent alternatively left and right. We wish to present the results of our simulations, which test SAOOH over scenes of various reflectivity, water content and topography. These simulations yield encouraging first results and let us see how some choices made in its on-board processing algorithm affect the random noise, the water detection performance and the point-target response.
Tidewater Glaciers and Ice Shelves as Self-Organising Systems
Authors: Benn Douglas , Åström Jan , Wheel Iain , Luckman Adrian , Nick Faezeh
Published: March 2024

Marine-terminating glaciers and ice shelves are notoriously complex, with a wide range of ice-dynamic and calving processes occuring in response to oceanographic, atmospheric and glaciological influences. Within this complexity, however, we can recognise order on at least two scales. First, marine ice fronts typically form vertical cliffs, reflecting competition between oversteepening (ice flow and melt-undercutting) and failure. Calving magnitude-frequency distributions have power-law form with an exponent of -1.2, characteristic of self-organising criticality (SOC). Such systems have a critical point as an attractor, such that the system converges on the failure threshold.The second scale is that of the whole ice tongue. Tidewater glaciers and ice shelves typically oscillate around stable positions for multiple years, punctuated by transitions to new quasi-stable positions. Stability is encouraged by pinning points which function as attractors at thresholds between stable and metastable states. Ice tongues may exist in metastable states for variable amounts of time, from days to decades. Factors encouraging rapid relaxation to the threshold include large stress gradients and rapid basal melt, and factors encouraging long relaxation times include low stress gradients, low melt rates, and buttressing from mélange or sea ice. Calving magnitude-frequency distributions have exponential form, reflecting the stochastic nature of calving in the metastable zone.Both scales of self-organisation emerge spontaneously from physically-based calving models such as the Helsinki Discrete Element Model (HiDEM) and the crevasse-depth (CD) calving law implemented in Elmer/Ice. Purely deterministic models, however, are not optimal for long-term simulations, especially in Antarctic contexts. We present results of preliminary simulations using a stochastic CD calving law, which opens up the possibility of a universal calving model applicable to both the Greenland and Antarctic ice sheets.
Drivers of the time-varying heat-cold-mortality association in Spain
Authors: Achebak Hicham , Rey Grégoire , Lloyd Simon , Quijal-Zamorano Marcos , Méndez-Turrubiates Raúl Fernando , Ballester Joan
Published: March 2024

Background: A number of studies have reported reductions in mortality risk due to heat and cold over time. However, questions remain about the drivers of these adaptation processes to ambient temperatures. We aimed to analyse the demographic and socioeconomic drivers of the downward trends in vulnerability to heat- and cold-related mortality observed in Spain during recent decades (1980-2018).Methods: We collected data on all-cause mortality, temperature and relevant contextual indicators for 48 provinces in mainland Spain and the Balearic Islands between Jan 1, 1980, and Dec 31, 2018. Fourteen contextual indicators were analysed representing ageing, isolation, urbanicity, heating, air conditioning (AC), house antiquity and ownership, education, life expectancy, macroeconomics, socioeconomics, and health investment. The statistical analysis was separately performed for the range of months mostly causing heat- (June-September) and cold- (October-May) related mortality. We first applied a quasi-Poisson generalised linear regression in combination with distributed lag non-linear models (DLNM) to estimate province-specific temperature-mortality associations for different periods, and then we fitted univariable and multivariable multilevel spatiotemporal meta-regression models to evaluate the effect modification of the contextual characteristics on heat- and cold-related mortality risks over time.Findings: The average annual mean temperature has risen at an average rate of 0·36°C per decade in Spain over 1980-2012, although the increase in temperature has been more pronounced in summer (0·40°C per decade in June-September) than during the rest of the year (0·33°C per decade). This warming has been observed, however, in parallel with a progressive reduction in the mortality risk associated to both hot and cold temperatures. We found independent associations for AC with heat-related mortality, and heating with cold-related mortality. AC was responsible for about 28·6% (31·5%) of the decrease in deaths due to heat (extreme heat) between 1989-1993 and 2009-2013, and heating for about 38·3% (50·8%) of the reductions in deaths due to cold (extreme cold) temperatures. Ageing (ie, proportion of population over 64 years) attenuated the decrease in cold-related mortality.Conclusion: AC and heating are effective societal adaptive measures to heat and cold temperatures. This evidence holds important implications for climate change health adaptation policies, and for the projections of climate change impacts on human health.
Grain size distribution of bulk-sample, detrital zircons and rutiles from the Yangtze River: implications for the sediment routing
Authors: Guo Rujun , Sun Xilin , Li Chang’an , Wegner Wencke , Zhang Zengjie , Wei Chuanyi , Li Yawei , Klotzli Urs
Published: March 2024

Changes in the grain size distribution of river sediment have environmental, ecological and social implications. This study investigated the variation of the grain size of bulk samples, detrital zircons and rutiles from the mainstream and major tributaries of the Yangtze River. The mean size of bulk samples from the upper reaches is significantly higher than the mid-lower reaches. The Equivalent Spherical Diameter (ESD) of most zircons (from previous work) and rutile grains fall within the range of 32-250 μm with dominant size of 63-125 μm. Coarse-sized zircons and rutiles with ESD of 125-250 μm are found in higher proportions in the upper reaches than in the mid-lower reaches, and a significant grain size decrease is observed downstream of the Three Gorges Dam. The significantly decreasing in coarse grains downstream of the dam indicates that the massive sediment contributed by the Three Gorges Dam (TGD), especially coarse-sized sediment. Our study demonstrates that a complex sediment routing system like the Yangtze River is interrupted by the Three Gorges Dam. The problem of grain-size bias caused by human activities on age-data acquisition and interpretation of detrital minerals (rutile and zircon) from large rivers is not negligible and deserves more attention when using single grain geochronology to constrain sediment provenance and tectonic evolution.
Ocean Bottom Seismic Model in the Knipovich Ridge area
Authors: Czuba Wojciech , Mjelde Rolf , Murai Yoshio , Janik Tomasz
Published: March 2024

The structure of the oceanic crust generated by the ultraslow-spreading mid-ocean Knipovich Ridge still remains relatively uninvestigated compared to the other North Atlantic spreading ridges further south. The complexity of the Knipovich Ridge, with its oblique ultraslow-spreading and segmentation, makes this end-member of Spreading Ridge Systems an important and challenging ridge to investigate. At spreading rates below 20 mm/y, ultraslow spreading ridges are characterized by a low melt supply. The Ocean Bottom Seismometer (OBS) data along a refraction/reflection profile (~280 km) crossing the Knipovich Ridge off the western Barents Sea was acquired by use of RV G.O. Sars on July 24 - August 6, 2019. The project partners are University of Bergen, Institute of Geophysics, Polish Academy of Sciences, and Hokkaido University. The seismic energy was emitted every 200 m by an array of air-guns with total volume of 80 l. To receive and record the seismic waves at the seafloor, ocean bottom seismometers were deployed at 12 positions with about 15-km spacing in 2 deployments. All the stations were recovered and correctly recorded data. Seismic energy from airgun shots were obtained up to 50 km from the OBSs. The profile provides information on the seismic crustal structure of the Knipovich Ridge and oceanic and continental crust in the transition zone. Seismic record sections were analyzed with 2D trial-and-error forward seismic modeling. This profile is a prolongation of the previously acquired profile AWI-20090200 (Hermann & Jokat 2013) and together will allow to interpret of ~535 km long transect crossing the Knipovich Ridge from the American to the European plate. This work is supported by the National Science Centre, Poland according to the agreement UMO-2017/25/B/ST10/00488. The cruise was funded by University of Bergen. Hermann, T. and Jokat, W., 2013. Crustal structures of the Boreas Basin and the Knipovich Ridge, North Atlantic. Geophys. J. Int., 193, 1399–1414, doi: 10.1093/gji/ggt048
Pulse of the Hall term compared to the frozen-in term and the triggering mechanism of magnetic reconnection at the reconnection point
Authors: Huang FuCheng
Published: March 2024

 The Hall effect closely relates to the decoupling between the motion of ions and that of electrons during magnetic reconnection. It is the key to understand the triggering mechanism of magnetic reconnection. In our previous research result, the energy cascade at the reconnection point is first found (Huang et al. 2018, GRL). It leads to the pulse of the Hall term compared to the frozen-in term at the reconnection point, explaining well the motion decoupling between ions and electrons . In order to understand better the energy cascade at the reconnection point, we will study further the physical process which acts between the energy cascade at the reconnection point and the motion of plasma waves in the reconnection region. The wave-number distribution of both magnetic field and electric field is investigated by use of simulation. The role of Landau damping of KAW in the reconnection region is discussed in detail based on the simulation result. It is also provide a physical mechanism to understand the resistivity which is essential for the colisionless reconnection.
Assimilation of HY-2D scatterometer wind field data in CMA-GFS
Authors: Wei Chuanwen , Han Wei , Liu Yan , Hu Hao , Lu Huijuan , Xiao Hongyi , Wang Dan
Published: March 2024

Satellite sea surface wind fields can compensate for the shortcomings of conventional observation data, thereby improving the forecasting skills of global medium-range numerical weather models. China successfully launched the HY2D satellite carrying a Ku band microwave scatterometer (HSCAT) on May 19, 2021. It can provide a large amount of high-quality sea surface wind field data for numerical forecasting models. In order to test the potential application of HY2D sea surface wind field data in the Global Assimilation Forecasting System of the China Meteorological Administration (CMA-GFS). A three-step study was conducted, with the first step being the timeliness evaluation of HY2D wind, followed by the quality evaluation of HY2D wind using ERA5 and buoy data, and finally assessment of impacts of the HY2D wind assimilation on the analyses and forecasts. Two sets of assimilation experiments were conducted: the control experiment without HY2D wind (CTRL) and sensitivity experiment with HY2D wind based on a new quality control scheme (HY2D-FlagQC). The experimental period is from March 1, 2023 to April 1, 2023. The results show that the timeliness of HY2D wind field obtained through National Satellite Ocean Application Service (NSOAS) has been improved by about 20% compared to Koninklijk Nederlands Meteorologisch Instituut (KNMI). But the timeliness fluctuation is relatively large in terms of time and space. The root mean square error of HY2D wind field is less than 2m/s. After assimilating the HY2D wind, the analysis errors of the wind fields in the lower-middle troposphere of the tropics and the southern hemisphere (SH) are significantly reduced. Furthermore, assimilating the HY2D wind data can improve the forecast skill of wind, geopotential height, and temperature in the troposphere of the tropics and SH. 
The gully system on the NW sector of La Fossa cone (Vulcano Island): 2D evolution and hazard implication
Authors: Fornaciai Alessandro , Favalli Massimiliano , Nannipieri Luca , Turchi Agnese , Bonasia Rosanna , Di Traglia Federico
Published: March 2024

The Island of Vulcano is the emerged portion of a composite volcanic edifice within the Aeolian volcanic archipelago, situated in the southern Tyrrhenian Sea. The remobilization, triggered by heavy rainfall, of loose volcaniclastic material from La Fossa cone and the generation of small debris flows are recurrent hazards on Vulcano. Although these debris flows generally transport small volumes of material, in the case of severe events, they can  be channeled along the roads, flood several buildings, inundate the main harbor, and eventually be discharged into the sea. Gravitational and erosive processes, mainly due to rainfall, have formed several gully systems around the La Fossa cone. The presence of gully systems along slopes enhances both runoff and downslope mass wasting, and, above all, the gullies themselves act as a source of mass wasting due to the collapse of their walls and the processes of aggradation and degradation of their beds. Therefore, understanding the behaviour of gullies and their response to rainfall is crucial for predicting the effects of environmental changes, whether climatic or volcanic, on gully dynamics. In the frame of "VOlcaniclastic debris flows at La Fossa cone (Volcano  Island): evolution and hazard implication (VOLF)" project funded by the Istituto Nazionale di Geofisica e Vulcanologia, we here analyze aerial photos of the NW sector of La Fossa cone to describe the evolution of its gully system from the 1954 to 2022. First, we create a georeferenced dataset of photos by orthorectifying existing photos and generating new ones through the Structure from Motion (SfM) method applied to Unmanned Aerial System (UAS) photos. Second, we describe the geomorphological features of the gullies in the NW sector of La Fossa cone, identifying features to be parameterized. Finally, we qualitatively and quantitatively describe their evolution over almost 70 years.  This work aims to investigate the morphological evolution of the NW flanks of La Fossa cone, a crucial aspect for assessing hazards associated with volcaniclastic sediment-charged flows and floods on Vulcano Island. This is especially relevant in a scenario where ongoing climate changes may potentially disturb the current equilibrium, heightening the likelihood of short-term extreme rainfall events.
Back reaction of magnetic field on rotating penetrative convection
Authors: Barman Tirtharaj , Das Arpan , Sahoo Swarandeep
Published: March 2024

The origin of the Earth's and planetary magnetic field is thought to arise from the convective flow of conducting liquid metal, particularly iron, in the deep interior of planetary systems through dynamo action. In numerical simulations, the nature of the resulting magnetic field depends on the imposition of buoyancy profiles that drive convection. Additional influence of imposed magnetic field on convective flows have been studied to understand the back reaction of dynamo action on fluid flow. In the present study, onset of  magnetoconvection is investigated to understand the physical effects in polar regions of the Earth's core where buoyancy forces exhibit a substantial component along the rotation axis. A simplified plane layer convection setup has been used to investigate the fundamental physical mechanisms. Various strengths of uniform magnetic fields in both horizontal and vertical directions have been incorporated. The novel aspect of the study is the incorporation of thermally stable layers with weak and strong stratification. Imposition of thermally stable stratification reduces the threshold of convective instability. It also restricts heat transport to unstable regions only. However, rapid rotation favors penetration of axial velocity into the thermally stable region, although critical thermal forcing for initiating convection also increases. The spectral characteristics of the flow is significantly modified due to the imposition of a stable stratified layer with background uniform magnetic field.
Variations in tropospheric ozone driven by Rossby Wave Breaking events over the Indian subcontinent through Remote Sensing Retrievals
Authors: Thomas Biyo , Kunchala Ravi Kumar , Singh Bhupendra Bahadur , Kondapalli Niranjan Kumar
Published: March 2024

Rossby wave breaking (RWB) is a significant pathway for intrusion of stratospheric ozone into the troposphere. These events increase tropospheric ozone, which influences the greenhouse effect, atmospheric chemistry, and local ecosystems. As RWBs frequently affect the Indian subcontinent, a comprehensive study is required to understand the impact of RWB-induced ozone variations in the troposphere over the study region. To identify the RWB events, we used a contour searching algorithm and analyzed them for the period from 2004 to 2021 for Indian domain. Furthermore, we analyzed the anomalous ozone variability during the detected RWB event days using the CAMS global reanalysis (EAC4) and two independent satellite data sets, the Microwave Limb Sounder (MLS) and the Atmospheric Infrared Sounder (AIRS). Additionally, we utilized ground-based observations from the CPCB to examine the influence of RWB on the changes in surface ozone. The results of our study suggest that the CAMS reanalysis agrees well with the two independent satellite products, which provide a comprehensive understanding of ozone variability from various datasets. The upper-level potential vorticity anomaly allows ozone evolution to begin a few days before the strongest breaking time and intensify on the strongest day. Moreover, RWB enables the vertical intrusion of ozone down to 750 hPa, with variations observed from one case to another. Intrusion strength yields diverse tropospheric column increments (e.g., 190.5 ppbv at 100-150 hPa). Surface ozone response (850 hPa) to RWB correlates with intrusion intensity, resulting in 10-19 ppbv ozone anomalies. This could arise from the augmented tropospheric column ozone due to turbulent mixing. These findings deepen our understanding of RWB–related ozone variability and its impact on surface levels.
Ridge-formation simulations in three dimensions using discrete element methods
Authors: Muchow Marek , Polojärvi Arttu
Published: March 2024

Sea-ice ridges form as a part of sea-ice deformation, while the ice is moved by winds and ocean currents. While ridging is a localized process, it is assumed to limit the compressive strength of sea ice in large scale. However, formulations of large-scale ice strength, as used in Earth System Models, do not consider individual ridge formation processes in detail. Thus, it is necessary to understand the energy spend in ridge formation and various processes related to generating ice rubble and redistributing it. To investigate ridge formation in detail, we use the Aalto University in-house discrete-element-method (DEM) model. This three-dimensional DEM model features deformable, multi-fracturing, ice floes, which can fail and form ridges when coming into contact, while recording the ridging forces. With this, we discuss why three-dimensional simulations are important to investigate ridge formation process.
Machine-Learning-based Relocation Analysis: Revealing the Spatiotemporal Changes in the 2019 Cotabato and Davao del Sur Earthquakes
Authors: Sawi Paulo , Kita Saeko , Bürgmann Roland
Published: March 2024

From October to December 2019, the provinces of Cotabato and Davao del Sur in the Philippines experienced an earthquake sequence that involved five M~6 (Mw 6.4, 6.6, 5.9, 6.5, and 6.7) inland earthquakes. A deep-neural network-based phase picker, PhaseNet, was used to obtain the seismic phases of earthquake waveforms of stations within 200 km from the area of the events for 80 days from October 16 to December 31, 2019. The acquired seismic phases were initially associated and located using the Rapid Earthquake Association and Location (REAL). Subsequently, the initial hypocenter locations were adjusted through relocation utilizing VELEST, with further refinement achieved through a relative relocation technique hypoDD. By employing these methodologies, we successfully created an earthquake catalog that contains ~5,000 earthquakes for the corresponding period. The number of determined earthquakes through this method surpassed the ~3,000 event count reported in the original catalog by DOST-PHIVOLCS which depended solely on manually selected seismic phases. The spatial distribution of the relocated hypocenters reveals two seismic alignments: one trending in the SW-NE direction, parallel to the existing mapped active faults, and the other in the NW-SE direction. These lineaments intersect near the location of the Mw6.4 event, suggesting the presence of a conjugate fault or cross fault. The created earthquake catalog illuminates the spatial and temporal evolution of seismicity following each significant event, offering insights into the detailed patterns that characterize the clustering of aftershocks.