bluuebunny/crossref_metadata_2025 huggingface dataset:
Using explainable machine learning to better understand source and process contributions to atmospheric bio-aerosol
Authors: Zhang Hao , Song Congbo , Topping David , Crawford Ian , Gallagher Martin , Chan Man Nin , Lee Hing Bun martin , Xing Sinan , Ng Tsin Hung , Tai Amos
Published: March 2024

The role of atmospheric bio-aerosols as determinants of environmental and human health outcomes is receiving more attention. However, a lack of fully evaluated end-to-end detection techniques hinders our understanding of identifying bioaerosol types and their environmental drivers, particularly in complex environments. In this study we mitigate these challenges through development of a novel machine learning framework that combines unsupervised deep learning and explainable machine learning techniques. The first step combines bidirectional long short-term memory autoencoder (Bilstm-AE) and a relatively new hierarchical, fast, clustering technique. Our results indicate that this approach outperforms other models, successfully distinguishing between fungal spores, non-biological aerosols, and pollen solely based on fluorescence information without the need for training data. Subsequently using automated machine learning and the SHapley Additive eXplanation (SHAP) method, we quantitatively discerned the environmental drivers of bioaerosol types. The variation of SHAP value indicated that the elevated pollen concentrations at night could be attributed to changes in its air mass composition and origins. More importantly, we find ambient evidence that pollen may break into smaller fragments when RH is over 90, leading to significant changes in its fluorescence spectrum and a rapid increase in its concentration. Overall we find that combining unsupervised deep learning and explainable machine learning could provide new insights into type-specific bioaerosols process.
A Radial Standing Pc5-6 Wave and Its Energy Coupling With Field Line Resonance Within the Dusk-Sector Magnetosphere
Authors: Yi-Jia Zhou , Fei He , Xiao-Xin Zhang , Archer Martin , Yu Lin , Han Ma , An-Min Tian , Zhong-Hua Yao , Yong Wei , Binbin Ni , Wenlong Liu , Qiu-Gang Zong , Zu-Yin Pu
Published: March 2024

Global ultra-low frequency (ULF) oscillations are believed to play a significant role in the mass,energy, and momentum transport within the Earth's magnetosphere. In this letter, we observe a ∼1.2 mHzradial standing wave in the dusk-sector magnetosphere accompanied by the field line resonance (FLR) on 16July 2017. The frequency estimation from the simple box model also confirms the radial standing wave. Theessential characteristics of FLR are concurrently identified at the dusk-sector magnetosphere and the conjugatedground location. Further, the radial standing wave dissipates energy into upper atmosphere to enhance thelocal aurora by coupling itself to the FLR. The magnetospheric dominant 1.2/1.1 mHz ULF waves plausiblycorrespond well with the discrete ∼1 mHz magnetosheath ion dynamic pressure/velocity oscillation, suggestingthis radial standing wave and FLR in the flank magnetosphere may be triggered by the solar-wind and/ormagnetosheath dynamic pressure/velocity fluctuations.
Understanding the hyporheic methane cycle based on field investigations in a small stream
Authors: Michaelis Tamara , Wunderlich Anja , Baumann Thomas , Einsiedl Florian
Published: March 2024

Global methane emission estimates from aquatic ecosystems, especially from rivers, remain highly uncertain due to a lack of high-resolution (temporal and spatial) data. Over three years, we have gathered data on the methane cycle in the river Moosach, a small stream in Southern Germany, to increase our conceptual understanding of the methane cycle in the hyporheic zone.The methane distribution in the streambed was measured at ten geochemical profiles with a 1 cm vertical resolution during different seasons and at several locations in the stream. Measurements of the stable carbon isotopes of methane (13C), in conjunction with analyses of the microbial community distribution, were used to decipher pathways of methane production and oxidation. To unravel the relevance of different transport pathways, methane ebullition was monitored weekly for one year at four test sites and compared to diffusive fluxes across the sediment-water and water-air interfaces. Quantifying the oxidation of methane to CO2 proved to be the most challenging part of the project. Especially when it came to distinguishing which reduction processes the oxidation was coupled to. This is because the observed geochemical gradients in the hyporheic zone were very steep, and dissolved oxygen reduction and denitrification zones often overlapped.Dissolved methane concentrations were generally high and reached up to 1000 µmol L-1 but had a heterogeneous distribution. Ebullition transported up to 30 times more methane to the atmosphere than diffusive fluxes, although this was also highly site-specific and subject to significant seasonal variations. From the isotopic difference in 13C between dissolved methane in the surface water and in gas bubbles, we estimated that up to 44% of the methane transported diffusively was oxidized.Taken together, these results show a high methane production in the hyporheic zone of river Moosach. The highly depleted stable carbon isotope composition of methane suggests a large contribution from hydrogenotrophic methanogenesis but the abundance of certain microbial groups and high ebullition in winter also indicate that methanol could be a substrate for methane production. Methane was oxidized at the top of the hyporheic zone, as shown by a clear isotopic enrichment in 13C of methane in several geochemical profiles, but could only marginally reduce greenhouse gas emissions since most methane escaped to the atmosphere as gas bubbles. Dissolved oxygen, nitrate, and nitrite were possible electron acceptors for methane oxidation. Factors favoring methane emissions were higher temperatures, high organic carbon contents in the hyporheic zone, and a fine-grained but permeable bed substrate that ensured anoxic conditions while allowing good exchange with the surface water. Spatial heterogeneity appeared to be larger than temporal variations, which renders extrapolation from point measurements a challenge for the overall assessment of greenhouse gas emissions.
Modeling the source temperature of fast and slow winds using a 16 moments multi-species model
Authors: Lomazzi Paul , Thomas Simon , Rouillard Alexis , Poirier Nicolas , Réville Victor , Lavarra Michael , Blelly Pierre-Louis
Published: March 2024

Understanding the general properties of the various solar winds requires an understanding of the phenomena at their source. The properties of the solar wind are influenced by the exchange of energy at the base of the solar corona. For example, the speed of the solar wind is strongly influenced by the level of heating below the sonic point. The heating that occurs in the collisional part of the atmosphere modifies the ionisation level of the heavy elements and therefore their charge state. This is why the charge state ratios of heavy ions measured in the solar wind are good parameters for distinguishing between fast and slow solar winds. In this study, we use the new Irap solar atmospheric model (ISAM) to study the level of ionisation of heavy ions transported in fast and slow solar winds. ISAM is a 16-moment multi-species model that self-consistently couples the transport equations for neutral and ionised particles (H, p, e, He, O and Mg) from the lower chromosphere through the solar corona to the solar wind. The lower corona is a region that is strongly coupled to the transition region by the downward heat flux. By solving first for H, p and e, we recover the results of previous modelling showing that variations in the source temperature modify the pressure of the transition region which, in turn, modulates the mass flux of the solar wind. Using an ad-hoc heating function characterised by a scale height inversely proportional to the expansion factor of the magnetic field lines channelling the solar wind, we first recover the general properties of the fast and slow solar winds, as well as the known observation that the source temperature of the slow wind is higher than that of the fast wind. We then solve explicitly the ionisation processes and the coupled transport of oxygen with the major species (H, p, e) in order to isolate the different processes that contribute to the ionisation level of the heavy ions. We compare the results of our modelling with spectroscopic and in situ data. This work was funded by the ERC SLOW SOURCE - DLV - 819189.
The effectiveness of oyster reefs as a nature-based erosion control measure under storm events
Authors: van de Lageweg Wietse , van Steen Thijs , Walles Brenda , de Smit Jaco
Published: March 2024

Coastal ecosystems such as oyster reefs, salt marshes and mangroves are widely recognised as nature-based solutions reducing coastal erosion. Oyster reefs maintain their own habitat and have the ability to grow at the rate of sea level rise, making them self-sustainable, flexible and cost-effective coastal erosion measures in the face of climate change. By attenuating waves and stabilising sediment as well as facilitating and protecting neighbouring ecosystems, they stimulate coastal resilience. However, effective employment of oyster reefs as a nature-based erosion control measure is not trivial and requires the integration of ecological and engineering parameters. Given the satisfaction of these eco-engineering parameters, recent work demonstrates that oyster reefs lead to a four-fold reduction in erosion in the protected area compared to a non-protected area across a decadal period. Despite this apparent effectiveness across a longer time period, it is still poorly understood how effective oyster reefs are in reducing erosion during individual storm events and how large their morphological footprint during these events is.We present the findings of a series of detailed morphological field surveys of the Viane oyster reef in the Eastern Scheldt, the Netherlands, during which three storm events (Ciaran, Gerrit and Henk) were captured. These storms led locally to significant wave heights of 1.3-1.5 m, corresponding to the highest percentile of wave events recorded locally. Results show that storm Ciaran resulted in an transect-average erosion of 0.02-0.05 m for the unprotected areas, corresponding to the typical annual erosion for the intertidal flats of this area. In contrast, the reef-protected areas showed a greatly reduced erosion of maximum 0.02 m but typically 0.01 m. It is important to note that the erosion pattern as a result of this storm event is far from homogeneous: erosion is greatest immediately behind the reef (~first 50 m), then reduces up to 150 m behind the reef, followed by a zone of deposition (150-250 m behind the reef) and then transitions into another zone of erosion (250-450 m behind the reef). Complementary numerical modelling with XBeach will be used to obtain additional insights into the role of wave angle, wave period and tidal timing on the flow, sediment transport and morphological changes caused by the Viane reef structure during storm events.
Decadal predictions outperform projections in forecasting winter precipitation over the Mediterranean region
Authors: Nicolì Dario , Gualdi Silvio , Athanasiadis Panos
Published: March 2024

The Mediterranean region is highly sensitive to climate change, having experienced an intense warming and drying trend in recent decades, primarily due to the increased concentrations of anthropogenic greenhouse gases. In the context of decision-making processes, there is a growing interest in understanding the near-term climate evolution of this region.In this study, we explore the climatic fluctuations of the Mediterranean region in the near-term range (up to 10 years ahead) using two different products: projections and decadal predictions. The former are century-scale climate change simulations initialized from arbitrary model states to which were applied anthropogenic and natural forcings. A major limitation of climate projections is their limited information regarding the current state of the Earth’s climate system. Decadal climate predictions, obtained by constraining the initial conditions of an ensemble of model simulations through a best estimate of the observed climate state, provide a better understanding of the next-decade climate and thus represent an invaluable tool in assisting climate adaptation.Using retrospective forecasts from eight decadal prediction systems contributing to the CMIP6 Decadal Climate Prediction Project (CMIP6 DCPP) and the corresponding ensemble of non-initialized projections, we compare the capabilities of the state-of-the-art climate models in predicting future climate changes of the Mediterranean region for some key quantities so as to assess the added value of initialization. Beyond the contribution of external forcings, the role of internal variability is also investigated since part of the detected predictability arises from internal climate variability patterns affecting the Mediterranean. The observed North Atlantic Oscillation, the dominant climate variability pattern in the Euro-Atlantic domain, as well as its  impact on wintertime precipitation over Europe are well reproduced by decadal predictions, especially over the Mediterranean, outperforming projections. We also apply a sub-sampling method to enhance the respective signal-to-noise ratio and consequently improve precipitation skill over the Mediterranean.
Modeling Wildfire Dynamics in Latin America Using the FLAM Framework
Authors: San Pedro Johanna , Krasovskiy Andrey , Corning Shelby , Kiparisov Pavel , Kraxner Florian
Published: March 2024

The increasing frequency of wildfires caused by climate change poses a significant threat globally, particularly in Latin America – a region known for its critical ecosystems. Its vulnerability to climate change-induced wildfire threats, resulting from increasing temperatures and changing precipitation patterns, is uncertain, highlighting the need for comprehensive strategies such as incorporating advanced modeling and proactive measures to understand, manage, and conserve its ecological state  in the face of  threats posed by climate change, such as wildfires. This study utilizes the wildFire cLimate impacts and Adaptation Model (FLAM) by IIASA to provide a comprehensive analysis of past and projected wildfire dynamics in Latin America. FLAM is a process-based fire parameterization algorithm used to assess the impacts of climate, fuel availability, topography, and anthropogenic factors on wildfire characteristics. It is highly adjustable and adaptable, making it suitable to analyze past and future wildfire trends in diverse regions such as Latin America. We analyzed spatial and temporal wildfire patterns using MODIS satellite data alongside historical climate and anthropogenic data to calibrate FLAM. We generated projections of burned areas until 2100 under 3 RCP scenarios for Latin American as a whole, as well as for distinct sub-regions to better assess regional wildfire dynamics and climate change impacts. Moreover, we developed a scenario to explore the impacts of increased fire suppression efficiency on projected burned area and highlight the impacts of focusing mitigation and management efforts on areas identified as hotspots (high risk of wildfire).The study shows FLAM’s effectiveness in modeling historical wildfires and its sensitivity to the RCP scenarios in predicting wildfire trends in Latin America. Our analysis and results show how FLAM helps in evaluating the potential future changes in wildfire intensity, and geographic spread under various climatic scenarios.  FLAM projected a dramatic rise in burned area until the end of the century across Latin America in line with observed trends, especially under severe climate change scenarios. Regions with the highest temperature rises are also prone to reduced precipitation, which further increase  wildfire risks. The spatially-explicit projections highlight  areas at higher risk of wildfire, enabling targeted and efficient fire management and mitigation strategies. Our study further showed the potential impact of adaptive measures, such as enhanced fire suppression efficiency in identified hotspots, in reducing annual mean burned area. Overall, this study provides critical insights into the relationship between climate change and wildfire dynamics using a state of the art model. It sets the foundation for further research on fires in Latin America and efficient management strategies which can be modelled by FLAM.
Analysis of historical flood events in Denmark with information from digital news media
Authors: Pedersen Jonas Wied , Mikkelsen Peter Steen , Butts Michael Brian
Published: March 2024

Reliable information on historical flood events is critical for flood risk analysis, climate change adaptation, verification of forecast models, etc. Unfortunately, such information is often difficult to find, due to e.g. lack of monitoring equipment at the location of a flood. In Denmark, management of water has traditionally been the responsibility of local authorities, which means there is a limited national overview of historical events and their consequences. Previous studies have employed different strategies for compiling a flood event inventory, including mining information from (1) insurance data, (2) social media data, and (3) newspaper archives. The aim of this study is to exploit a comprehensive digital news media archive to compile an inventory of Danish flood events in the period 2007-2020 with information on the time and location of the event, to classify the type of flood, and note any available information on local consequences and damages.We have gained access to the company Infomedia’s large digital media archive, which consists of digitized articles from news sources ranging from major national newspapers to small, local outlets. The archive contains more than 75 million news articles with the earliest articles dating back to 1990. The archive is searchable through calls to an API with a custom search language that combine user-specified keywords. A hydrologist has read all articles that match the keywords, noting all the relevant information.1,118 distinct flooded locations where identified over the 14-year period of 2007-2020. Results show that there is large year-to-year variability in the different types of floods. Urban pluvial floods are experienced somewhere in Denmark every single year, while the number of both fluvial and storm surge floods are very low (or entirely missing) in some years. Urban pluvial floods occur throughout the year but are highly concentrated in the summer months with a mean date of occurrence in late July, while storm surges are observed only between September and March with a mean date in mid-December. Fluvial floods are the least concentrated type of floods and occur throughout the year with a slight overweight in winter months (mean date in early January). The spatial distribution of floods is uneven with four out the 10 municipalities that experience the highest number of floods being located in Eastern Jutland (Vejle, Horsens, Kolding, Aarhus) and another four located in the Northern half of Zealand (Copenhagen, Roskilde, Gribskov, Holbæk).Storm surge events occur over large geographical areas and we therefore speculate that they are more likely to be reported in news media than urban pluvial floods, which are often local events due to the small-scale nature of convective rainfall cells. Ongoing work is trying to quantify these aspects and validate the individual flood events in the inventory using additional data sources.
Chemical characterisation and comparison of Isoprene Organosulphates in simulation chamber experiments and ambient aerosol samples in the Amazon rainforest
Authors: Hildmann Stefanie , Wasserzier David , Hopson Lea , Kremper Leslie , Pöhlker Christopher , Hoffmann Thorsten
Published: March 2024

In tropical forests, organic material accounts for a large fraction of particulate matter and the contribution can be as high as 90 % at the submicrometer scale, mainly through the formation of secondary organic aerosols (SOA) from the oxidation of biogenically released volatile organic compounds (VOCs). Despite the abundance of organic material and the important role these particles play in the rainforest boundary layer, the composition of submicrometer organic aerosols is poorly understood (Andreae et al., 2015; Hallquist et al., 2009).Several different biogenic VOCs are released in tropical regions, but it is undisputed that isoprene is emitted in such large global quantities (600 Tg year-1) that the formation of SOA results in significant production of atmospheric particulate matter even at small yields (Chen et al., 2015; Liu et al., 2016).  NOx concentrations have a strong influence on SOA production, but SO2 also affects SOA composition.  Reactions of acidic sulphate aerosol with Isoprene derived oxidation products leads to the formation of organosulphates (OS) that provide information about mixtures of biogenic gases and anthropogenic pollutants. Due to the large variety of formation processes, the composition of SOA is very complex and varies constantly. To understand the formation and transformation processes, specific molecular marker compounds must be identified and quantified. Methyltetrol sulphates and methyltetrols are isoprene SOA markers that are formed from isoprene-derived epoxydiols (IEPOX). However, organosulphates have proved analytically challenging to quantify, due to lack of authentic standards and the complex sample matrix in which they are observed.This study provides a suitable analytical tool for chemical characterisation of such isoprene derived organosulphates by combining high performance liquid chromatography (HPLC) with electrospray ionisation ultra-high resolution orbitrap mass spectrometry (ESI-UHR-Orbitrap-MS). Chamber simulation experiments  were performed to investigate isoprene OS formation by comparing different atmospheric reaction pathways and authentic standards were synthesised to enable complete identification of individual OS compounds. Marker compounds for aged isoprene derived organic aerosols could be assigned and quantified in ambient aerosol samples of the Amazon rainforest. Moreover, it could be shown that the lack of authentic standards has led to significant underestimation of isoprene derived OS concentrations in the past. Andreae, M., Acevedo, O., et al. (2015), Atmos. Chem. Phys., 15(18), 10723-10776.Chen, Q., et al. (2015), Atmos. Chem. Phys. 15(7), 3687-3701.Hallquist, M., Wenger, J. C., et. al. (2009), Atmos. Chem. Phys., 9(14), 5155–5236.Liu, Y., et al. (2016), PNAS, 113(22), 6125-6130. 
Sensing enabled submarine telecom networks for seismology
Authors: Morten Jan Petter , Wienecke Susann , Waagaard Ole Henrik , Brenne Jan Kristoffer , Rønnekleiv Erlend
Published: March 2024

Distributed acoustic sensing (DAS) on submarine fiber optic cables will contribute to resilient societies by significantly enhancing environment and hazard monitoring. Recent studies have emphasized applications to earthquake and tsunami early warning, volcanic eruptive events observation, and characterizing climate change effects. Widespread deployment of DAS instrumentation on the existing cable networks traversing the coastal zones and oceans can vastly expand data coverage with real-time capabilities at low cost. The use of DAS in existing long-haul telecommunication systems has so far been limited since most DAS interrogators rely on optical wavelengths that interfere with the existing telecom traffic. Recent developments in DAS technology enable co-existence of telecom traffic with the sensing application. Lab and field investigations have demonstrated that there is no detrimental effect from the interrogation on the transmission line performance when the DAS instrument is configured to operate at sufficiently separated wavelength channels. Thus, it is possible to utilize all existing cable networks for sensing applications in unison with continued telecom transmission without sacrificing any capacity in the link and maintaining high-quality DAS measurements.This study describes a DAS deployment on a submarine cable system with live telecom traffic. The interrogation scheme facilitates consistent high sensing sensitivity exceeding 120 km range. The data quality and interrogator performance are quantified, and the localization and characterization for a representative set of environmental and anthropic signal sources is shown. We will describe real-time processing and detection implementations that transform such sensing enabled submarine telecom networks into measurement arrays suitable for seismic monitoring. Moreover, the technical solutions for DAS installation with existing terminal equipment and the practical aspects of data sharing will be described.
Development and verification of preconcentrator to measure clumped isotopologues (Δ13CH3D and Δ12CH2D2) of methane from the atmosphere and sources
Authors: Defratyka Sara , Rennick Chris , Wilson Freya , Clog Matthieu , Houston Andrew , Arnold Tim
Published: March 2024

Bulk isotopic signatures (δ13C-CH4 and δD-CH4) are widely used for determination of methane source types and relative contributions. For example, these measurements are implemented as additional tracers in top-down studies. However, for some sources, for example certain fossil fuels sources in Europe and waste sector, the bulk isotopic signatures are overlapping, thus some methane sources remain indistinguishable1–4.The multiply substituted (clumped) isotopes can be used as additional tracers to better distinguish methane sources, and potentially, better understand methane sinks. Measurement of methane clumped isotopes, Δ13CH3D and Δ12CH2D2 is more challenging than measurements of bulk isotopes and requires more advanced instruments 3,5–8. Currently, a NERC project called POLYGRAM aims to develop the sample preparation (automated preconcentration) and measurement infrastructure to measure atmospheric air samples using High Resolution - Isotope Ratio Mass Spectrometer (HR-IRMS), to determine clumped isotopes from air samples collected at the world-recognised global monitoring sites at Cape Point, South Africa and station Zeppelin, Svalbard. Moreover, the project also aims to determine the clumped isotopes ratios of methane sources, like wetlands, agriculture or coal mines, as currently clumped isotopes database is constrained.Use of custom-built preconcentrator is a key step in the measurement chain, as HR-IRMS requires ultra-pure methane samples to measure clump isotopes. For ambient air studies, our aim is to obtain, at ambient pressure, a 150 ml sample containing at least 1% of methane from hundreds of litres of ambient air, where CH4 mole fraction is less than 2 ppm. To achieve it, we aim to concentrate methane in our sample by up to 62500 times. Additionally, we develop our preconcentrator to prepare samples containing at least 1% of methane from gas samples containing
Simulating Arctic aerosol-cloud interactions in a warm air intrusion event during the MOSAiC campaign
Authors: Price Ruth , Field Paul R. , Engdahl Bjørg Jenny Kokkvoll , Landgren Oskar , Rinke Annette , Orr Andrew
Published: March 2024

Aerosols play a crucial role in determining the characteristics and radiative impacts of Arctic clouds. Parameterisations of aerosols and clouds in climate models remain uncertain, confounding efforts to improve our understanding of their behaviour both now and in the future. Moreover, model biases in cloud microphysics are compounded by interlinked biases in Arctic boundary layer structure, surface properties and large-scale meteorology. This interdependence among variables poses significant hurdles for modelers attempting to accurately simulate Arctic atmospheric processes.
In this study, we have used a regional atmospheric model, the UK Met Office Unified Model, coupled to a cloud microphysical model (Cloud Aerosol Interacting Microphysics, CASIM) and an aerosol-chemistry-climate model (UK Chemistry and Aerosols, UKCA). This integrated approach has been employed to investigate warm air intrusion events during April 2020 of the MOSAiC campaign. Our results provide vital information on the behaviour of model processes that have been tuned for mid-latitude regimes, such as cloud droplet activation, in the Arctic environment during warm air intrusion events that had clear impacts on the surface energy budget. 
Behaviour of Kinetic Electron and Proton Instabilities in the Magnetosheath Modelled with Semi-Implicit Particle-In-Cell
Authors: O'Neill Stuart , Boella Elisabetta , Micera Alfredo , Verscharen Daniel , Innocenti Maria Elena
Published: March 2024

Temperature anisotropies are often encountered in space and astrophysical plasmas. A sufficiently large ratio between the electron temperatures perpendicular and parallel with respect to the magnetic field causes whistler and mirror instabilities to grow. Similarly, a sufficiently large perpendicular proton temperature ratio is expected to result in instabilities such as mirror and proton acoustic instabilities. In the parameter regime surrounding Earth’s magnetosheath linear theory predicts that proton cyclotron instability will have the lowest threshold of all anisotropy-driven instabilities. Despite this, unstable mirror modes are observed in apparent contradiction to linear theory. It has been suggested that an electron perpendicular to parallel temperature anisotropy can alter the relative growth rates of mirror and proton acoustic instabilities by boosting the growth rates of mirror modes. Such an anisotropy could also be consumed by (faster) electron instabilities. Given the potential for cross-species interplay, a thorough understanding of the behaviour of the electron whistler instability, which typically grows fastest compared to instabilities in the electron species, is crucial. By leveraging multidimensional kinetic simulations with the Energy Conserving Semi-Implicit Method ECSIM, this work studies the competition of electron instabilities in parameter space typical of Earth’s magnetosheath. In addition, the possibility that residual electron temperature anisotropy left over after the saturation of electron instabilities can affect the proton acoustic to mirror competition is explored. This second part of the study relies on the semi-implicit nature of the ECSIM code, which allows spatial and temporal resolution to be dimensioned on the basis of the smallest and fastest dynamics expected in the system, rather than the Courant condition that one has to respect for stability in explicit PIC codes. 
A Physics-informed Deep Learning Based Clustering to Investigate the Impact of Regional European Radiative Forcing on Arctic Climate and Upper Atmospheric Dynamics
Authors: Mehrdad Sina , Handorf Dörthe , Höschel Ines , Karami Khalil , Quaas Johannes , Dipu Sudhakar , Jacobi Christoph
Published: March 2024

Heterogeneous radiative forcing in mid-latitudes, such as those caused by aerosols, has been observed to influence the Arctic climate, although the underlying mechanisms continue to be a subject of scientific discussion. In this research, we employed Deep Learning (DL) methodologies to explore the complex response of the Arctic climate system to localized radiative forcing over Europe. We performed sensitivity experiments using the Max Planck Institute Earth System Model (MPI-ESM1.2). By applying a DL-driven clustering approach, we classified atmospheric circulation patterns within a reduced-dimensional framework, with a particular focus on Poleward Moist Static Energy Transport (PMSET) as our primary parameter of interest. Additionally, we developed a new methodology to assess the contributions of these circulation patterns to anomalies in various climatic parameters.Our results demonstrate that anomalous negative forcing over Europe alters existing circulation patterns and their occurrence frequency without leading to the emergence of new patterns. The clusters change between the Experiment and Control runs in two main ways: variations in their frequency of occurrence and seasonal shifts between the class mean characteristics in the Experiment and Control runs. While pronounced changes in seasonal occurrence frequency can substantially contribute to the observed seasonal anomaly, even subtle alterations in the seasonal differences between class mean characteristics can profoundly affect the class's contribution to the anomaly, especially if that cluster occurs with a high frequency.We identify changes in the circulation pattern with the high-pressure system over Scandinavia as a key driver for reduced sea ice concentration (SIC) in the Barents-Kara Sea in autumn through enhancing the PMSET. The alterations in this circulation pattern also impact the dynamics of the middle atmosphere. However, its influence is relatively minor compared to other circulation patterns that are analogous to the various phases of the North Atlantic Oscillation (NAO). These results shed light on the complex interactions between diverse atmospheric circulation patterns and climatic variables, revealing the underlying mechanisms responsible for the anomalies observed across different seasons. Notably, a complex interplay of different circulation patterns, particularly those mirroring the distinct phases of the NAO, plays a crucial role in dictating wave propagation and the dynamics within the stratosphere. While our study did not specifically investigate the stratospheric pathway, our findings highlight that regional negative radiative forcing over Europe can lead to changes in both Arctic climatic parameters and the dynamics of the stratosphere.
Exploring the efficiency of anaerobic oxidation of methane as a sink to hydrate-sourced methane
Authors: De La Fuente Ruiz Maria , Arndt Sandra , Marín-Moreno Héctor , Minshull Tim A. , Vaunat Jean
Published: March 2024

Ocean warming threatens methane hydrate stability in continental margins, potentially leading to methane release into marine sediments, the water column, and ultimately the atmosphere. Over the decadal to millennial timescales during which hydrate-sourced methane release is anticipated, microbially mediated anaerobic oxidation of methane (AOM) in marine sediments may mitigate benthic methane efflux. While traditionally considered a highly efficient biofilter, recent studies reveal significant variability in the AOM sink efficiency. For instance, in cold seep settings, efficiency ranges from 80% to 20% with slow to high fluid flow, respectively, and this decreases to around 10% in pristine seepage environments. This variability is directly related to the balance between multiphase methane transport and the growth dynamics of microbial communities.In this study, we use a novel 1D multiphase reaction-transport model to investigate the transient evolution of the AOM sink efficiency and its impact on seafloor methane emissions in response to a centennial-scale methane release caused by climate-driven hydrate destabilization. We examine the combined influence of gaseous methane transport, including induced tensile fracturing by pore fluid overpressure, and methanotrophic biomass dynamics on weakening the efficiency of the AOM sink. Preliminary findings suggest that the AOM sink is notably limited to mitigating benthic methane emissions in gassy sediments. Additionally, the slow growth rate of methane-oxidizing microorganisms may lead to significant temporal windows for methane to escape into the ocean. This integrated analysis provides insights into the intricate dynamics governing the efficiency of the benthic AOM sink subjected to hydrate-sourced methane. It contributes to a more comprehensive assessment of potential methane emissions in continental margins in the context of global warming.
Spontaneous destabilization of a compositionally stably stratified mantle in the Early Earth
Authors: Hansen Ulrich , Dude Sabine
Published: March 2024

Crystallization processes, a partial or complete overturn of the early mantle and other processes can lead to a compositionally stably stratified mantle which may hinder of even prevent convective currents. In the classical view, the layer will be stable if the restoring force, generated by the compositional stratification will exceed the driving force as provided by heating the layer from the core. The situation resembles the diffusive scenario of double diffusive convection, characterized by the fast diffusing component (heat) being the driving force, while the slowly diffusing component (composition) acts as the restoring force. If perturbed, subcritical convection can eventually take plain ce.  While in  pure thermal convection , subcritical flow only develops as localized patterns, in the double diffusive case, a perturbation can lead to a global destabilization (blue sky bifurcation) of the system, due to a sufficient finite  amplitude perturbation. . In this study we have investigated the influence of a finite amplitude perturbation of varying magnitudes , namely realze by an impact on a stably stratified mantle. Numerical experiments in 2- and 3D, cartesian and spherical simulations, based on a Finite Volume scheme  have been conducted to study the evolution of such a system. Key parameters  which characterize the evolution are the (1) initial stratification and the structure f the perturbation. The viscosity structure is a further influencing factor.The experiments show that an impact into a stably stratified mantle can lead to a global destabilization, giving rise to complex flow patterns, including local and transient layering of the mantle flow. An evolutionary path of a planet from a stably stratified state to a complex layered period and/or to a full convection mode seems sensitive.
H2 formation in subduction zone
Authors: Gauthier Alexis , Larvet Tiphaine , Le Pourhiet Laetitia , Moretti Isabellle
Published: March 2024

Dihydrogen (H2) is a promising decarbonized energy source, but traditional artificial production methods emit CO2 and/or consume a lot of energy. However, there are natural sources of H2 on Earth originating from diverse geochemical processes. A recent study above the Nazca plate subduction in the Andes, detected variations in the H2 emanation function on the slab dip angle. This H2 release is likely the result of peridotite hydration in the mantle wedge, notably through serpentinization. The water required for peridotite hydration is sourced from dehydration of the subducting plate as it sinks into the Earth's mantle.This study aims to understand the influence of slab dip angle on H2 production in the mantle wedge using the pTatin2D code. Fluid circulation were implemented based on two principles:The hydration and dehydration capacity of rocks under varying pressure and temperature conditions is predicted using tables from the thermodynamic software PerpleX.
The velocity of free water is equivalent to that of surrounding rocks, with a vertical component related to percolation.
Numerical simulations show that in the case of flat subduction, the mantle hydration zone, where H2 is produced, is wide and extending up to 500 km from the trench. On the other hand, in the case of a steep subduction, the zone is narrower, and is located between the trench and the volcanic arc. Magma formation competes with H2 generation for the use of water released from the subducting plate. During the transition from steep to flat subduction, the mantle hydration zone undergoes widening while the volcanic zone migrates significantly away from the trench. This transition may also trigger oceanic crust melting, resulting in a shift in magma composition before the volcanism intensity diminishes and then disappears.
Svalbard Integrated Arctic Earth Observing System: Tools to help you do fieldwork in Svalbard
Authors: Jones Eleanor L. , Matero Ilkka S. O. , Hübner Christiane , Denkmann Rudolf , Morris Ashley , Godøy Øystein , Lihavainen Heikki
Published: March 2024

Svalbard Integrated Arctic Earth Observing System (SIOS) is an international consortium in which 28 member institutions from 10 countries cooperate to develop and maintain a regional Earth observing system in and around Svalbard. We will present some of the tools that this consortium uses to facilitate fieldwork within Earth System Science. Firstly, our Logistics Sharing Notice Board is a platform where you can offer spare logistical resources or ask for logistical support with your fieldwork. Secondly, our Observation Facility Catalogue can help you learn about existing infrastructure and measurements in Svalbard, and you can even enter your own instruments and infrastructure. In addition, our e-learning platform is a valuable resource for newcomers to research and fieldwork in Svalbard and our data catalogue provides an overview of and access to relevant existing datasets. Finally, SIOS offers funding to facilitate access to the research infrastructure owned by SIOS member institutions (our Access Programme), as well as to improve infrastructure in and around Svalbard (our Optimisation Programme).
31P NMR Reveals Predominance of Small Molecules in Organic Phosphorus within NaOH-EDTA Soil Extracts
Authors: Haddad Lenny , Vincent Andrea , Giesler Reiner , Schleucher Jürgen
Published: March 2024

Organic phosphorus (P) plays a crucial role in maintaining the health and productivity of soils. Understanding the composition of organic phosphorus in soils is thus relevant to a range of disciplines, spanning from agricultural sciences to ecology. Over the past few decades, efforts have been directed towards characterizing and quantifying various soil organic P compounds and determining their turnover rates. Despite these efforts, the precise nature of soil organic P remains unclear, particularly that of orthophosphate monoesters, which dominate 31P NMR spectra of NaOH-EDTA extracts globally.Typically, the monoester region of 1D 31P NMR spectra appears as a series of sharp signals "sitting" on a broad background where the broad background can account for a substantial part of the monoester region. This is prompting questions about how to integrate and identify these signals and to what extent this fraction may be ecologically important. To investigate this monoester background, we employed 1D 31P NMR and 2D 1H-31P NMR1, along with 31P transverse relaxation (T2)2 measurements to calculate intrinsic linewidths. We related this linewidth to molecular weight to unveil the nature of the observed background. Analysing seven soils from different ecosystems, we observed linewidths ranging from 0.5 to 3 Hz for both resolved monoester signals and the background. This suggests that the background comprises numerous, possibly exceeding 100, sharp signals associated with small (
Representing mean wind speed profile over urban canopy with building height variability
Authors: Nakao Keisuke , Kikumoto Hideki , Takimoto Hiroshi , Hongyuan Jia , Xiang Wang
Published: March 2024

 The horizontal mean wind speed profile in vertical direction within and above urban canopy (UC) is an essential information to drive the exchange of momentum, heat, moisture and pollutants in atmosphere. Well-known profiles in logarithmic and exponential layers, which express upper and lower wind over UC, respectively, are efficient assumptions used to express UC wind profile. This study attempted to add the intermediate layer (IL) between those two-layers to include the effect of building height variability on the mean wind speed profile. Large-eddy simulations (LESs) of UC with building height variability were conducted using a wide range of morphology parameters, that is, plan area index, aspect ratio, and the standard deviation of building height. A tendency of the bulk drag coefficient of the IL was expressed by the plan area index and the frontal area index at the intermediate layer. The wind speed at IL was modeled linearly by the length- and velocity-scale analysis. By parameterizing the coefficients of these three layers, we attempted to analytically represent an entire wind speed profile by the three-layer wind profiles. The results indicated reasonable consistency in the wind speeds at mean building height and the momentum flux with LES data. Effect of the thermal stratification was investigated by the correction of the length-scale in IL.
Unraveling the structure and function of soil food webs using an untargeted lipidomics approach
Authors: samrat Rahul , wanek Wolfgang
Published: March 2024

Belowground (soil) communities are highly diverse and encompass higher plants, bacteria, fungi, protists, invertebrates and vertebrates. The feeding relationships are as diverse, ranging from symbiotic associations (e.g. mycorrhizae), saprotrophs, grazers, shredders, predators and parasites. These material flows underly the biogeochemical functions of soils, driving organic matter decomposition, soil carbon sequestration, nutrient recycling and greenhouse gas emissions. Despite the importance of understanding the structure and dynamics of such complex soil food webs we are still lacking quantitative and detailed approaches to characterize them. Recently lipidomics analysis of intact polar lipids of soil communities has emerged indicating its potential to allow disentangling the food web structure beyond just abundances of bacteria and fungi based on phospholipid fatty acids or amplicon sequencing data, but extending this analysis across the whole soil food web including its base, higher plants, and including higher consumer levels with diverse protists and invertebrates Our study introduces and develops an untargeted lipidomics platform, employing reversed-phase liquid chromatography and electrospray ionization tandem mass spectrometry (UPLC ESI Orbitrap MS), to examine the intact polar lipidomes of soil biota. With advanced high resolution mass spectrometry and a newly adopted bioinformatics toolbox, we analyze lipidomes from complex soil communities and from pure cultures and single species, including plants, archaea, bacteria, fungi, protists (amoebozoa, ciliophora, cercozoa, etc.), collembola, mites, nematodes, and other soil fauna, as well as their diets. Our workflow facilitates the rapid identification and quantification of thousands of unique intact polar lipid molecules, representing a variety of biological classes, which we currently analyze for their biomarker potential, for being indicative for the presence and activity of specific groups of soil organisms. Utilizing this method of biomarker analysis, finally in combination with isotopic tracing into the fatty acyl residues (containing carbon, hydrogen and oxygen) and the lipid head groups (containing additionally nitrogen, sulfur and phosphorus), is expected to provide valuable quantitative insights into the structure of soil food webs and their activity and matter transfer, by following the incorporation and transfer of isotopically labeled matter and how this responds to climate and land use change. Thereby we foresee to improve our understanding of the contributions made by soil organisms to the stability and function of soil ecosystems, thus providing a foundation for ongoing ecological and environmental research.