bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of Ozone above Togo during the 1979–2020 Period
Authors: Ayassou Koffi , Pazmiño Andrea , Sabi Kokou , Bazureau Ariane , Godin-Beekmann Sophie
Published: March 2024

The objective of this paper is to estimate the trend of the Total Ozone Column (TOC) over Togo. A Multi-Sensor Reanalysis-2 (MSR-2) of the TOC over the entire territory of Togo was used. A Multiple Linear Regression (MLR) method has been applied to retrieve the interannual contributions of different forcings and the long-term variability. It was found that the Annual Oscillation (AnO), the Quasi Biennial Oscillation at 30 mb (QBO30), the Solar Flux (SF), and the El Niño–Southern Oscillation (ENSO) has a statistically significant influence on the interannual variability of the TOC. The strongest contribution (22 ± 1.4 DU) is allocated to the AnO while the weakest (<1 DU) is attributed to the Semi-Annual Oscillations (SAnO). Before the peak year of the Equivalent Effective Stratospheric Chlorine (EESC) in the tropics in 1997, the trend is negative (−0.3% ± 0.9% per decade) and is not statistically significant. After the peak year, a statistically significant positive trend is observed. The trend of the TOC is 0.6% ± 0.2% per decade. The monthly TOC trend over Togo is positive and statistically significant during the rainy season (particularly during the monsoon period) except in April, unlike during the harmattan period (DJF), where the trend is not significant.
Unveiling Microplastic Pollution in the Air: Optimizing filter material and Work-up in PM10 studies
Authors: Schumacher Mareike , Lederer Albena , Fischer Dieter
Published: March 2024

Microplastics (MP) are prevalent environmental pollutants found in urban, rural, and remote locations worldwide. Although aquatic and soil samples are extensively studied, the examination of aerosol samples is a relatively new area of research. The investigation of inhalation exposure to nano- and microplastic particles is particularly noteworthy, given that the portion of particulate matter (PM) with an aerodynamic diameter less than 10 µm (PM10) is believed to exert the most significant impact on human health. Analyzing MP involves the application of mass-balanced or particle-related methods. To allow the applicability of both methods, the election of filter material during sampling is crucial. Membrane filters like quartz fibre filters (QFF) are the material of choice used for various types of analytes due to their high uptake capacity of PM. The direct analysis of the sampled QFF with particle related methods is impeded without particle extraction, since microscopic methods require all analytes to be detectable on the surface.The mechanical stress induced on the filters during extraction leads to an extensive fibre loss of the filter material that aggravates the following evaluation. A pre-sampling filter treatment for QFF with potassium silicate solution (K2SiO3 ⋅ n H2O, also known as water glass) as inorganic adhesive is presented. The advantages of the improved filter properties during post-sampling processing for microscopic analysis are shown and results are compared to non-treated filters.A multiple step QFF work-up is applied including particle extraction, digestion (removal of organics by employing chemical treatment) and density separation. Since every processing step is prone to particle loss, the evaluation of recovery rates is essential. We present two approaches for quality assurance within the particle size range of interest. The optical approach allows the assessment in terms of absolute particle numbers, while mass spectrometry method provides the particle loss specified in mass.After successful work-up, we are combining both method types by using Raman Microscopy (µRaman) and Pyrolysis Gas Chromatography-Mass Spectronomy (py-GC/MS) for the characterisation of MP. This combination raises the possibility to compare the results of both method types. We will show that the combination of both methods can be a significant contribution to the analysis of MP in the atmosphere. 
Model geometry determined contrast in the feedback between compositionally originating LLSVPs and dynamically generated plates
Authors: Lowman Julian , Langemeyer Sean , Tackley Paul
Published: March 2024

Nearly three decades of investigation has made steady progress towards self-consistently generating multiple features of plate tectonics from global mantle convection models.  Accordingly, the modelling of dynamic plates with migrating boundaries and evolving areas has become commonplace in both 2-D and 3-D geometries. Investigating the properties required for obtaining durable deep mantle formations similar to the Large Low Shear-wave Velocity Provinces (LLSVPs) has received similar attention. In this study, we model LLSVPs by assuming their composition is persistent  (i.e, we assume steady-state chemistry). To this end, we incorporate a Compositionally Anomalous Intrinsically Dense (CAID) mantle component comprising 2–3.5 per cent of the total mantle volume. We explore the impact of both an intrinsic contrast in density and viscosity for the CAID component, in an effort to stimulate the formation of a pair of LLSVP-like structures and a surface that exhibits the principle features of terrestrial plate tectonics; including recognizable and narrowly focused divergent, convergent and (in 3-D) transform plate boundaries that separate 8–16 distinct plate interiors. Although we find that a pair of CAID material provinces can be readily obtained in 2-D calculations while maintaining a surface exhibiting plate-like behaviour, specifying the same system parameters in 3-D calculations does not yield a pair of enduring provinces for any values of the parameters investigated.  In addition, CAID component inclusion in the calculations can affect global geotherms, so that in comparison to the surface behaviour obtained for the initial condition isochemical model, the cases incorporating the dense component do not yield surfaces that simulate plate tectonics. In general, CAID material components that are 3.75–5 percent denser than the surrounding mantle (at surface temperatures), and up to a factor of 100 times greater in intrinsic viscosity, form layers populated by voids, or nodes connected by ridges that reach across the core–mantle boundary (CMB), rather than distinct piles resembling the morphology of the LLSVPs. However, due to their temperature, we find the CAID material forms masses on the CMB that are relatively less dense (0.625–1.5 per cent) and viscous than the adjacent mantle material, in comparison to the percentage differences obtained at common temperatures. By adjusting our yield stress model to account for the influence of the CAID material on the geotherm, we find a highly satisfactory plate-like surface can be re-attained. Nevertheless, the formation of a pair of LLSVP-shaped masses remains elusive in 3-D calculations with plate-like surface behaviour and we suggest that caution is required if inferring the physical properties of the LLSVPs from 2-D models.
The Lithosphere Structure Of Bohai Bay Basin: Combining Gravity, Geoid, And Topography Data
Authors: Ma Jing , Wang Wanyin , Zeyen Hermann , Li Zhongsheng
Published: March 2024

The Bohai Bay Basin, located in northeast China, is a Meso-Cenozoic strike-slip extensional basin. A lot of research work carried out in Bohai Bay Basin, has shown that there is a huge potential of oil and gas resources. However, the proportion of known oil and gas reserves to the total estimated resources is not high, which means that this area still has broad exploration prospects. Although oil and gas resources are mainly distributed in sedimentary basins, their enrichment degree is largely influenced by the structure and development of the lithosphere. Based on lithospheric local isostasy theory and thermal conduction principle linked to temperature dependence of rock densities, the three-dimensional deep structure of the lithosphere under the Bohai Bay Basin is calculated by using geoid and gravity anomalies, topographic and existing geological-geophysical data. The results show that the lithosphere-asthenosphere boundary of Bohai Bay Basin gradually rises from the western onshore to the eastern offshore area from 90 to 110 km. The thinnest lithosphere is found under the Bozhong Depression in the southeast of the Bohai Bay Basin. It is concluded that the thinning of the lithosphere in the Bohai Bay Basin is closely related to the subduction of the Meso-Cenozoic Pacific plate, which led first to thickening followed by delamination of the North China Craton lithosphere, and then the magma upwelling led to slow uplift of the Earth’s surface and continuous stretching of the lithosphere. At the same time, favorable conditions of temperature, pressure, chemistry and structure were provided for the formation of oil and gas. In this wqy, the Bohai Bay basin developed into the present oil-rich basin. This study provides a new perspective for understanding the deep structure and hydrocarbon resource control mechanisms of Bohai Bay Basin.
A Bipolar Multi-Reagent Chemical Ionization Mass Spectrometer for Versatile Measurements of Gas and Particle Phase Organics
Authors: Canagaratna Manjula , Stark Harald , Williams Leah , Alton Mitch , Joo Taekyu , Lopez-Hilfiker Felipe , Avery Anita , Pospisilova Veronika , Gentner Drew , Lambe Andrew
Published: March 2024

Organic species in the atmosphere originate from a wide range of sources and processes. While real time chemical ionization mass spectrometry (CIMS) has improved our capability to characterize individual organic species in the atmosphere, the selectivity of CIMS reagent ions can limit the range of species that can be measured.  In this work the need to detect a broader range of species with a single CIMS instrument is addressed. A fast-switching bipolar time-of-flight CIMS that switches between four different reagent ions, including positive and negative ions, is demonstrated.  The performance and utility of this instrument is demonstrated by measurements obtained on board a ship in Antarctica during the PolarChange field campaign and from New York City during the AEROMMA campaign.  During both campaigns the instrument cycled through iodide (I-), benzene (C6H6+), and acetone dimer ((C3H6O)2H+) reagent ions at a 2 second data acquisition rate per cycle.  In the case of PolarChange, this combination of ions enabled simultaneous detection of trends in primary marine biological emissions such as dimethyl sulfide, nucleating species such as ammonia and methyl amine, and acids, such as nitric acid.  During AEROMMA, the fast bipolar switching capability enabled Eddy Correlation measurements of primary biogenic and urban emissions (i.e. monoterpenes and aromatics), secondary products of atmospheric oxidation (i.e. highly oxidized organics and organic nitrates), and reduced nitrogen species.  Preliminary results from this dataset, including positive matrix analyses of the combined multi-reagent ion datasets, are discussed.  Simultaneous gas and aerosol composition measurements obtained by coupling this mass spectrometer with aerosol inlets are also described.
Reducing our school's carbon footprint through composting the canteen food waste
Authors: Molinos Solsona Marta
Published: March 2024

Over one-third of global food production is estimated to contribute to the waste stream, leading to greenhouse gas emissions. Composting food waste emerges as a sustainable solution, effectively mitigating emissions by sequestering carbon in the soil, while also offering various environmental, economic and social benefits. However, food waste management pathways are mainly landfilling and controlled combustion, only a little fraction ends up being composted.Our secondary school is actively engaged in promoting recycling and sustainability within the scholar and local communities. With the active collaboration of students, we initially focused on separating light packing and paper, but we recognized that a substantial portion, approximately 40%, of our waste was organic waste from the school canteen. In response, we launched a composting initiative to convert this organic waste into valuable fertile soil.  Presently, four composters are consistently fed twice a week, yielding compost that enriches the soil in our school vegetable garden.This poster shows the comprehensive procedure, detailing the collection of food waste and the employed composting methods, including vermicomposting. The final product is a nutrient-rich organic material that enhances soil structure, fertility, ad moisture retention.This experience has not only significantly reduced our school’s waste output but has also played a pivotal role in raising awareness and educating students about climate change, waste-related issues, and the importance of local actions. Through active collaboration, we aim to install a sense of responsibility and environmental consciousness among students, fostering a sustainable mindset for the future.
Estimating terrestrial carbon dioxide and water vapor fluxes from geostationary satellites in near-real time: the ALIVE framework
Authors: Stoy Paul , Ranjbar Sadegh , Hoffman Sophie , Losos Danielle
Published: March 2024

The terrestrial carbon and water cycles can change rapidly in response to extreme events, human management, meteorological drivers, and more. Many established remote sensing-based estimates of terrestrial ecosystem function are not designed to observe such rapid changes. To address this shortcoming, we developed a machine learning (ML) approach trained on eddy covariance measurements to estimate terrestrial carbon dioxide and water vapor fluxes at five-minute intervals using geostationary (“weather”) satellite observations from the Advanced Baseline Imager on the GOES-R satellite series. Our approach, which we call ALIVE (Advanced Baseline Imager Live Imaging of Vegetated Ecosystems), creates a ‘hypertemporal’ view of terrestrial ecosystem functioning over the diurnal cycle and in near-real time.We will describe the training and testing procedure used to develop ALIVE with a focus on ML model skill and uncertainty estimation. We then compare ALIVE against the historical MODIS eight-day gross primary productivity (GPP) product to demonstrate how ALIVE can estimate the carbon cycle consequences of land management and extreme events to lead to an improved understanding of the carbon and water cycles. Comparisons during seasonal transitions and in response to extreme events including continental-scale wildfire smoke across North America in 2023 highlight the importance of rapid observations of land surface function.ALIVE is currently limited to the Conterminous United States (CONUS) and surrounding areas. We discuss the steps necessary to expand it, namely the availability of eddy covariance observations across the Americas and opportunities to apply the ALIVE framework to similar geostationary satellites worldwide like the new Meteosat-12 (formerly MTG-I1) which observes Africa, Europe, and parts of western Asia and is currently scheduled to become operational in Spring 2024. We also discuss opportunities to combine ALIVE estimates with other carbon and water cycle products in a remote sensing data fusion framework to help observe terrestrial ecosystems ‘everywhere, all the time’. By quantifying the carbon and water cycle across all of the time scales over which they vary, we hope to improve the ability of satellite remote sensing to understand our changing planet. 
Physical and chemical controls on ikaite (calcium carbonate hexahydrate) precipitation in seawater
Authors: Vickers Madeleine , Evans David
Published: March 2024

Ikaite, CaCO3•6H2O, is a metastable polymorph of calcium carbonate which is the parent mineral to glendonites (stellate calcite pseudomorphs found throughout the geological record). In the modern ocean, ikaite may be found below the sediment-water interface, or in tufa columns, at temperatures of 10 °C) suggests that this ikaite could have formed under warmer conditions than it does today, or that short-duration cooling interrupted hyperthermal episodes of the early Cenozoic (Vickers et al., 2024). As much uncertainty surrounds the timing, and physical and chemical conditions of the formation, and transformation, of the precursor ikaite, the usefulness of glendonite for (semi-)quantitatively reconstructing temperature and environmental conditions is uncertain, and the explanation for the early Cenozoic glendonites remains obscure. This study examines the physical and chemical controls on ikaite nucleation, growth and transformation in seawater, with a view to understanding trace element and isotope partitioning into ikaite and ikaite transformation products, and if and how certain elemental and isotopic environmental proxies may be applied to glendonite calcite phases.ReferencesBuchardt, B., Israelson, C., Seaman, P. and Stockmann, G., 2001. Ikaite tufa towers in Ikka Fjord, southwest Greenland: their formation by mixing of seawater and alkaline spring water. Journal of Sedimentary Research, 71(1), 176-189.Zhou, X., Lu, Z., Rickaby, R.E., Domack, E.W., Wellner, J.S. and Kennedy, H.A., 2015. Ikaite abundance controlled by porewater phosphorus level: Potential links to dust and productivity. The Journal of Geology, 123(3), 269-281.Vickers, M.L., Vickers, M., Rickaby, R.E., Wu, H., Bernasconi, S.M., Ullmann, C.V., Bohrmann, G., Spielhagen, R.F., Kassens, H., Schultz, B.P. and Alwmark, C., 2022. The ikaite to calcite transformation: Implications for palaeoclimate studies. Geochimica et Cosmochimica Acta, 334, 201-216.Vickers, M.L., Jones, M.T., Longman, J., Evans, D., Ullmann, C.V., Wulfsberg Stokke, E., Vickers, M., Frieling, J., Harper, D.T., Clementi, V.J. and Expedition, I.O.D.P., 2024. Paleocene–Eocene age glendonites from the Mid-Norwegian Margin–indicators of cold snaps in the hothouse?. Climate of the Past, 20(1), 1-23.
Recent developments in dust electrification research 
Authors: Nicoll Keri , Harrison R. Giles
Published: March 2024

Electrification of dust in the atmosphere is abundant, observed by helicopter blades glowing from corona discharge in dusty environments, and sparks from barbed wire fences during the US Dust Bowl.  Electrification of particles in blowing sand, dust devils and dust storms can result from contact charging/triboelectrification during dust generation or through its atmospheric transport, causing particles to accumulate large amounts of charge on their surface.  Strong electrostatic forces can affect the lofting of dust particles from the ground, as well as the transport of dust particles, however the details of such effects are still largely unexplored.  The charging of dust particles, and separation of the charge by mechanical processes yields large electric fields (E-fields, up to tens of kV m−1).  Satellite remote sensing of dust is based on measurements of electromagnetic wave propagation, which can be attenuated by large electric fields, thereby the accuracy of dust measurements can be affected by electric fields arising from charge separation in dusty environments. Such E-fields are also expected to alter the orientation of dust particles, changing the effective optical depth of dust layers, existing calculations for which assume randomly oriented particles.Although the existence of dust electrification has been known about for over a century, the details of the electrification mechanisms, and impact of dust electrification on particle behaviour are not yet fully understood.  This is partly due to a lack of observations of coincident space charge, E-field and particle measurements in dusty regions, particularly at altitudes above the surface.  This presentation will discuss recent research in understanding dust electrification processes, including surface observations of dust electrification in the United Arab Emirates (UAE), and measurements of charge in high altitude dust layers above the surface.
“Climate crisis and its impact: New ways to awaken curiosity and hope in the classroom environment”
Authors: Bredberg Camilla
Published: March 2024

Teaching about the ongoing climate crisis feels many times emotionally exhausting. This is particularly because it is often sensed that a large number of our students are hopeless about climate change and its impact. In our experience, we have also recognized that classroom discussions may result in misleading conclusions, namely that “if there is hope, is not for us”.  Therefore, in recent years, I have been trying to explore new methods to approach this subject. I have searched how students' interest about climate crisis, i.e., global warming and climate change, as well as their engagement as citizens to deal with climate crisis could be awakened.The aspects that I have particularly explored are as follows:1).Geological field studies together with scientists provides new insights into climate crisisSince 2013, I have been working on several projects in collaboration with researchers at the Department of Geological Sciences at Stockholm University. This collaboration began when I participated in a Research Council. Since then, I have been co-leading several projects, which had resulted in that many of my students participated in scientific activities, including making observations, collecting data, and doing fieldwork. By doing fieldwork my students have got new insights into and the time to reflect over the present as well as the past climate changes. This is a way of learning that the “climate crisis” is in fact “a geological problem”.2). Engagement creates hopeI have been involving my students in several cultural projects where they had the opportunity to express their thoughts about climate crisis to politicians, dream about future solutions, and to search why other people in the society make their voice heard through climate demonstrations. By participating and expressing their thoughts in such activities, my students realized that they could contribute making “Earth a wonderful planet to live on”. For examples, a group of them participated in a workshop co-organized by Stockholm University, the Researchers’ Desk, and Lava at Kulturhuset Stadsteatern. The students created textile messages to politicians and decision makers about climate change.In another project, my students have participated in the research project “Utopian stories”, a collaboration between the Department of Literary Studies and the Centre of Digital Humanities at the University of Gothenburg and the Bolin Centre for Climate Research at Stockholm University and the Nobel Prize Museum.
A Program to Introduce Students to Scientific Research and Build Capacity in STEM 
Authors: Damas M. Chantale
Published: March 2024

Engaging undergraduate students in research is considered a high impact practice (HIP), and has the potential to increase student persistence, retention, and graduation in science, technology, engineering, and mathematics (STEM). Through the use of large data sets freely available on the Internet, undergraduate students are engaged in applied research that contribute to the fundamental understanding of space weather’s impact on Earth’s space environment, life, and society.  Research and educational activities focus on a CubeSat mission and design for both space weather and climate change applications. Engaging undergraduate students in space science and technology research and education activities has the following broader impacts: 1) long-term integration of space weather into the undergraduate curricula, thus exposing students to research early in their academic careers; and 2) increasing students’ interest in and motivation to study science, technology, engineering, and mathematics (STEM), as well as preparing them for choosing a career path in space science and related fields. This work describes the program, as well as best strategies that are used to build capacity in space science and technology at the undergraduate level.
Utilization of clay-containing aggregate sludge waste as structural concrete and asphalt aggregate
Authors: Avci Erdi , Tugrul Atiye
Published: March 2024

In the aggregate quarries in Çiftalan and Ağaçlı (Eyüpsultan, Turkey) regions, grovak-shale type rocks belonging to the Thracian Formation are used as concrete and asphalt aggregates. After crushing, these rocks are classified into 0-5 mm, 5-12 mm and 12-24 mm sizes and marketed as concrete and asphalt aggregates. Aggregates with sizes larger than 5 mm can be used directly in concrete and asphalt applications without any washing process, while aggregates with sizes smaller than 5 mm are called fine aggregates and are marketed after the washing process since the methylene blue value is too high for concrete and aggregate. After the washing process, grains smaller than approximately 100 microns in size (especially clay minerals) are stockpiled in waste sites. Within the scope of this study, it is aimed to produce sinter aggregates with strength that can be used in concrete from these waste materials. It was determined that the waste materials with a grain diameter of less than 100 micron consisted of 28.6% quartz, 21.9% albite, 17% muscovite, 24.9% chlorite and 3.6% calcite minerals. In addition to minerals, 3.4% organic matter was detected. In addition, the main oxide compositions of these wastes were determined, and it was found that 54.51% SiO2, 18.1% Al2O3, 19.66% sum of fluxes (CaO, Na2O, Fe2O3, K2O, MgO) and 5.8% loss on ignition. Within the scope of determining the thermal properties of the wastes, DTA analyzes were carried out and it was determined that two different endothermic reactions took place in the range of 500-600 °C and 700-800 °C, thus dehydroxylation reactions took place in these temperature ranges. In the range of 1000-1100 °C, it was determined that an exothermic reaction, that is, a new phase or several phases were realized. Considering these thermal properties of the wastes, 1100 °C was determined as the sintering temperature. For the sintering process, the samples were first dried at 105 °C and then milled and powdered again. The powdered samples were placed in a metal cell with a diameter of 5 cm and a height of 10 cm and then compressed with a load of 200 kg per cm2. The compressed samples were heated to 1100 °C in a high temperature furnace with a temperature increase of 10 °C per minute and kept at 1100 °C for 30 minutes and then allowed to cool in the furnace. Since the height of these sintered cylindrical specimens was less than 10 cm, the Brazilian test method was used to determine their strength. As a result of the experiment, it was determined that the Brazilian test strengths of 3 different specimens reached 8.8 MPa, 9.6 MPa and 15.7 MPa. Considering the strength values obtained, it was determined that ideal products for concrete and asphalt aggregate can be produced from the dust wastes released in these aggregate quarries. 
Analysing spatial variability in drought sensitivity of rivers using explainable artificial intelligence
Authors: De Meester Joke , Willems Patrick
Published: March 2024

Several severe drought events occurred in the past years and droughts will likely occur more frequent and be more intense in the future. Hydrological drought, which reflects the shortage of water in the river system, can lead to economic losses and can have severe negative impacts on aquatic ecosystems. Therefore being able to predict and increase insights in which rivers are more vulnerable to hydrological droughts, based on catchment characteristics and human interactions, can be of relevance for water managers. In this analysis, the drought sensitivity of rivers is predicted at a regional scale (Flanders, Belgium). Hereby the interests of multiple stakeholders is taken into account by considering four drought metrics, namely the yearly summer volume, the number of dry days, the drought intensity and drought severity. Whereby the latter three are based on the ecological flow. To predict each of these drought metrics, five models ranging from statistical to tree-based methods are applied using twelve input variables ranging from catchment characteristics to human interactions. Hereby random forest without bootstrap and XGBoost outperforms the other methods. To increase the interpretability of the results, the XGBoost models are used to calculate the SHAP and SHAP interaction values. As a result, the impact of the different input variables on the model results is assessed.From this analysis, some general conclusions can be drawn. Irrigation is the most important variable for each of the considered drought metrics. However, not for every drought metric a clear, unique dependence between the irrigation and the drought sensitivity of a river could be observed. Rivers which have sand as dominant soil texture in their drainage area are less vulnerable to drought. When there are more human interaction in the drainage area, the river is more vulnerable to drought. Beside this, several other dependencies are observed of which many can be explained by the difference in ease of water transferability between sandy soils and clay soils. Next to this, it became clear that the impact of forest and agricultural area on the drought sensitivity of a river is complex, whereby especially its interaction with soil texture and human activities needs further investigation. The applied method can predict the drought sensitivity of a river based on catchment characteristics and human interactions, and therefore define rivers that are more vulnerable to drought. They moreover can provide additional insights in the importance of catchment characteristics and human interactions, and their relation to the drought sensitivity of a river.
Monitoring Based on Differential Radar Interferometry (DInSAR) of the Activity of San Miguel Volcano, El Salvador
Authors: Villalobos Ana Mirian , Tolomei Cristiano , Euillades Pablo , Bignami Christian , Euillades Leonardo , Trasatti Elisa
Published: March 2024

The present study demonstrates the application of time series techniques with Differential Interferometry Radar (MT-InSAR) using images from the Sentinel-1 (C-band) and SAOCOM (L-band) radar sensors. The main objective was to identify and assess ground deformation at the San Miguel volcano, one of the most active volcanoes in El Salvador, for study and monitoring purposes. Various approaches were employed to enhance phase signal quality, including the use of Small Baseline Subset (SBAS) and Persistent Scatterers (PS) MT-InSAR methodologies, as well as atmospheric corrections using both the GACOS (Generic Atmospheric Correction Online Service for InSAR) data and an altitude-dependent linear model able to estimate and then remove the stratified component of the troposphere. Additionally, orbital corrections were performed, and the impact of Digital Elevation Model (DEM) accuracy and updates of the topography on phase, especially for SAOCOM L-band images, were evaluated.The InSAR results revealed subsidence in the volcano crater showing a maximum rate of -25 mm per year, then we modeled the retrieved deformation patterns as a system of normal faults simulating two concentric craters. Moreover, limited deformation was detected in the western upper flank of the volcano during the 2023 period using SAOCOM data. We also observed that the volcano was strongly affected by atmospheric disturbances, although the performed corrections by using GACOS information did not yield to fully satisfactory results. In our work, the importance of using updated and accurate DEMs when processing L-band images has been emphasized.Finally, our study suggests to continue using SAR images for monitoring San Miguel volcano activity, implementing longer time series with SAOCOM, and performing comparisons between SAR data acquired from both C- and L-band, possibly covering the same period, to gain a more comprehensive understanding of the deformation occurring at San Miguel volcano, and to improve the understanding of the volcanic activity.
A Comparison of SimCLR and SwAV Contrastive Self-Supervised Learning Models For Landslide Detection
Authors: Shahabi Hejar , Ghorbanzadeh Omid , Homayouni Saeid , Ghamisi Pedram
Published: March 2024

Deep Learning (DL) algorithms have demonstrated superior efficacy compared to traditional Machine Learning (ML) methods in the realm of landslide detection through the analysis of Remote Sensing (RS) imagery. However, their performance is notably contingent upon the quantity of manual annotations utilized during the training process. This investigation delves into the utilization of two distinct Self-Supervised Learning (SSL) models, specifically the Simple Framework for Contrastive Learning of Visual Representations (SimCLR) and Swapping Assignments between multiple Views (SwAV). These models were adapted and enhanced for downstream tasks, particularly in the domain of landslide detection. To train the SSL models, the Landslide4Sense competition dataset was employed, consisting of 3799 training patches, 245 validation patches, and 800 testing patches generated from Sentinel-2 images acquired from diverse regions worldwide. During the training of SimCLR and SwAV models, only the training patches were utilized, with a series of data augmentations applied to the input dataset based on each model's architecture. Both models employed ResNet-50 as the encoder.For the downstream task of landslide detection, a custom U-Net model was developed. The trained ResNet-50 served as the encoder, and during fine-tuning, only the decoder part was permitted to be trained while the encoder remained frozen. During the fine-tuning process, subsets comprising 1% and 10% of labeled data from the training dataset were randomly selected to train the model, and predictions were exclusively conducted on the testing data. While a conventional supervised ResU-Net model, which was trained on all labeled training datasets, attained an F1 score of 72%, the SSL models achieved F1 scores of 64% and 71% with 1% labeled data, and 68% and 76% with 10% labeled data for SimCLR and SwAV, respectively. In addition, comparisons were conducted with all supervised reference models in the Landslide4Sense competition, revealing that SwAV, with 10% labeled data, outperformed all models, surpassing their top model by 4%. This study underscores the potential of SSL techniques in the segmentation and classification of RS images for natural hazard mapping, particularly in scenarios where labeled data is not available or is limited.
A winter temperature reconstruction based on the Bayesian approach in southwest China during the 18th-19th century
Authors: Chen Siyu , Brönnimann Stefan
Published: March 2024

Some classic approaches to climate reconstruction, such as employing transfer functions, have stringent requirements for the quality and continuity of historical records. As a result of limited data sources and complex topography, it’s hard to estimate the winter temperature in southwest China. However, the Bayesian approach allows integrating probabilities into the temperature indices and assimilating documentary information with different uncertainties with climate modeling data. Some gap years with less or even absent information in narrative sources could also be evaluated.Based on Bayes’ theory, a large-scale simulation ensemble containing 20 members called ModE-Sim serves for the estimate of prior atmospheric states. The documentary data, including abnormal phenomena records in the local history and official reports of precipitation, contain various information on snow, rainfall, flower phenomena, and personal feelings. They are used to generate Indices from extremely cold to warm as well as the associated likelihood of each winter and contribute to the reconstruction of the posterior probability. Finally, a series of winter temperature with uncertainty in southwest China during the 18th-19th century is generated from the prior and posterior probability.This new 200-yr reconstruction in this study fits well with an independent dataset called ModE-RA, which is a global monthly reanalysis also employing ModE-Sim as the background state of the atmosphere. The cold winters of 1700/1701, 1783/1784, 1809/1810, and 1892/1893 and the cold late 19th century are expressed in this reconstruction. This study presents a new application of the Bayesian approach in the historical climatology field and has the potential to contribute to the analysis of large-scale circulation in past winters in China.
Arctic methane emissions under novel disturbance regimes: interactions between permafrost thaw, changing precipitation, and peat fires
Authors: Turetsky Merritt
Published: March 2024

Cross-scale feedbacks between hydrology, vegetation, permafrost thaw, and wildfire will drive Arctic carbon cycle responses including methane emissions to the atmosphere. This presentation will summarize recent findings from several large-scale empirical projects examining interactions between disturbance regimes and their consequences for vegetation and carbon storage and fluxes in interior Alaska and northwestern Canada.  A long-term monitoring project at the Alaska Peatland Experiment (APEX) found that early onset of abrupt thaw, driven by active layer thickening with no visible thermokarst, was predicted by changes in the moss community and stimulated CH4 fluxes 5-fold, accounting for 30% of the total annual thaw-driven increase in CH4. Methane emissions at several sites in interior Alaska were sensitive to rainfall and surface moisture conditions, with spring rain events stimulating soil warming and methane fluxes. Finally, new tools have allowed us to identify and examine forests and peatlands that experienced overwintering or zombie fire conditions, with early results showing interesting regional differences in how these novel fire conditions influence fuel combustion and carbon release.  Results from recent and ongoing studies will be used to frame forward-looking research questions and approaches urgently needed to better understand the fate of permafrost carbon.  In particular, I will discuss several efforts to incorporate abrupt thaw into circumpolar upscaling and modeling studies. Unlike active layer thickening, abrupt thaw impacts meters of soil rapidly, occurs on a fine-scale not easily detected in remote sensing products, and is further destabilized by rainfall, wildfire, and vegetation change.
Interaction between aseismic slip phenomena in a collision orogen
Authors: Chen Kate Huihsuan , Ide Satoshi , Peng Wei , Hua I-Chu , Chen Chieh-Chih , Hsu Ya-Ju
Published: March 2024

Using continuous seismological data of Central Weather Administration (CWA) Seismographic Network and Broadband Array in Taiwan for Seismology (BATS), we applied the envelope correlation method of Mizuno and Ide (2019) to identify tectonic tremors in Taiwan 2012 to 2022. With a large number of seismic stations used in this study and removal of short-lasted events (< 10 s), we successfully detected ~7000 events. Except for the tremor zone previously observed at southern Central Range, we reported the new tremor “hotspots” across the mountain range of the island, over a distance of 200 km. Different from the fluid-rich environment previously established for tremors in subduction zones, the newly discovered tremor zones in Taiwan coincide with the spots with high geothermal heat flux, indicating that the temperature effect may be the common mechanism for tremor generation in a mountain belt of Taiwan.Other than tectonic tremors, several seismic phenomena are believed to be driven by aseismic slip process such as repeating earthquakes and earthquake swarms. The three catalogs may provide new insight into the controls of quasi-periodic aseismic slip and the role of deep fluid in their generation mechanism. We found that only < 5% of repeating earthquakes and swarms are located in 5 km of the tremor clusters, indicating that the deep-seated tremors might be engineered differently, comparing with the shallower repeaters and swarms. The spatial association is only observed underneath the southern Central Range, where the shallow swarms (< 15 km) and deep tremors (20-50 km depth) are likely interactive. We found 69-80% tremors and 86-96% swarm events occurred at the lower ground water level, respectively. This is contradictory with opposite clamping effect of hydrological/tidal stresses on thrust faulting (tremor) and normal faulting (swarm) slip. We hypothesized that in the lower crust where the thrust-faulting tremors are generated, the vertical fluid mobility could be easily elevated during the decreasing ground water level under the condition of near-lithostatic pore-fluid pressure. The upward migration of fluids may play an important role in the occurrence of swarm activities above the tremors. The continuous magnetotelluric monitoring at the location of active swarms will help us to confirm and further establish the temporal variation of fluid flow. 
Numerical investigation about propagation characteristics and hydro-sediment-morphodynamic interactions of multi-sized debris flow with a two-phase continuum model
Authors: Hu Peng , Lyu Binghan , Li Ji , Li Wei , Cao Zhixian
Published: March 2024

Debris flows are classical two-phase flows that can be enhanced by entraining multi-grain sizes of sediments from the bed as they rush down steep slopes, in which particle segregation is related to assessing the potential hazards. However, understanding the characteristics and fluid-particle interaction mechanisms remains challenging. Here an existing depth-averaged two-phase continuum flow model is further improved by incorporating the effects of pore-fluid pressure and bed sediment conditions on erosion. To demonstrate its reliability, we compare numerical solutions with measurements of thickness, front location, and bed deformation in two sets of USGS large-scale experimental debris flows over erodible beds. The following physical understandings are obtained. First, the positive effects of pore-fluid pressure and coarse bed materials on erosion rates are numerically reproduced. Moreover, an additional mechanism for this phenomenon has been revealed. Specifically, debris flows on steep slopes are likely to fall into a high shear stress regime, under which conditions the sediment transport capacity always takes a maximum value and is independent of the sediment size. Therefore, the sediment settling velocity that is proportional to the sediment size affects the erosion rate directly. Second, we probe into the non-dimension number and energetics of the debris flows to find it necessary to incorporate water-sediment and particle-particle interactions into reproducing the debris flow processes. Third, two kinds of mechanisms for particle size coarsening in the head region of the debris flow are resolved: on the one hand, they can be incorporated and retained there if the debris flow acquires sediment from the bed in transit due to considering the hiding/exposure mechanisms and on the other hand, they can migrate to the head by preferential transport. Furthermore, a series of idealized tests were conducted to explore the factors contributing to the segregation of particles within a debris flow. The longitudinal particle segregation was reproduced by incorporating the shear-induced non-uniform vertical distributions of velocity and sediment concentrations, the visco-inertial rheology, as well as the grain-size heterogeneity into the modelling. Sensitive analysis shows that the transport of fine particles is more inhibited by the interaction of the flow, contributing to the larger transportation velocity of the coarse particle. We further observed that the water content, the slope, and the particle size would have positive effects on the longitudinal size segregation in the head region, contrasting with the negative effects of the flow viscosity. These factors affecting the segregation ratio are attributed to the changes in the ratio of the Reynolds Number of the flow between fine and coarse particle.
A synchronously coupled global model iOM4: a new modeling tool for simulations of the ocean-cryosphere interactions 
Authors: Sergienko Olga , Harrison Matthew , Huth Alexander , Schlegel Nicole
Published: March 2024

Recent model developments have allowed to account for the effect of the Antarctic Ice Sheet in the Earth System Models (ESMs). Thus far, coupling between an ice-sheet model and other model components of an ESM is performed off-line, and the exchange of the relative fields is done once a year.  However, decades of remote sensing and in situ observations show that there is a tight coupling  between the Southern Ocean, sea ice and Antarctic  Ice Sheet on a variety of temporal scales, including seasonal and subseasonal. Interactions between the ocean, sea ice and ice sheet give rise to a number of feedbacks in this tightly coupled system. Investigations of such interactions and feedbacks require modeling tools capable of representing tight coupling between all three components.  In order to be able to accurately simulate these interactions, investigate feedbacks and mutual impacts of these components, we have  developed a synchronously coupled global ocean-cryosphere model iOM4. In this model,   a global ocean-circulation model MOM6, an ice-sheet model MOM6-IS, which is a component of MOM6, and a sea-ice model SIS2,  share the same horizontal grid; this ensures a tight coupling between the ice shelves and ocean circulation in the cavity.  As a demonstration of the coupled-model capabilities, we perform global simulations using JRA-55 reanalysis as the atmospheric forcing for MOM6 and SIS2 and the output of simulations of the regional model MAR forced with JRA-55 for MOM6-IS.
Rapid Estimation of 2022 Tonga Erupted Volume from the Remote Seismo-Acoustic Resonance
Authors: Lin Cheng-Horng , Shih Min-Hung , Lai Ya-Chuan
Published: March 2024

The powerful acoustic waves generated by the major eruption on January 15, 2022 on Hunga Tonga Hunga Ha’apai (HTHH) of Tonga were unambiguously recorded in Taiwan by several infrasonic stations and Formosa array, which consists of 146 broadband seismic stations with an average spacing of ~5 km in northern Taiwan. Based on the carefully analyses of the broadband frequency-wavenumber method (BBFK) and the Fast Fourier Transform (FFT), it was interesting to see that both data sets consistently showed a resonant frequency of ~0.0117 Hz persisted for more than 25 minutes after the first major eruption. Such a long-duration resonance of the remote seismo-acoustic waves provides a rapid estimation of the erupted magma volume of 0.215 ± 0.015 if the volcanic cavity produced by the erupting magma is considered as a classic Helmholtz resonator. Thus, we may obtain that the first major eruption alone of HTHH rated a 4 on the VEI scale. But the total erupted volume could reach up VEI 5 or even 6 if we consider all of the accumulated magma from the following eruptions.