bluuebunny/crossref_metadata_2025 huggingface dataset:
Very-high-resolution simulations with Harmonie-AROME of a heatwave case for the city of Pari with different landuse datasets.
Authors: Zonato Andrea , Theeuwes Natalie
Published: March 2024

In this work, various very-high-resolution simulations with the Harmonie-AROME Numerical Weather Prediction (NWP) model are performed for the city of Paris during an intense heatwave event in the summer of 2022, to evaluate the capability of the model to reproduce real conditions, at various resolutions and incorporating different kinds of landuse and urban morphology types. In particular, simulations are performed using ECWMF operational forecasts at 9 km resolution as boundary conditions, for the operational 2.5 km runs. Moreover, two 500 m and 100 m resolution domains have been one-way nested in the parent one.For considering the impact of urban areas, the state-of-the-art urban canopy parameterization Town Energy Balance (TEB, Masson et al., 2000), has been employed within the modeling system, and its single-layer and multi-layer options have been compared to evaluate the improvements brought by the multi-layer capability. To test the impact of various urban morphologies, simulations have been run with 1) the default ECOCLIMAP-SG landuse at 300-meter resolution, which considers urban areas as 10 different categories, derived from the WUDAPT Local Climate Zones Classification, and 2) the Geoclimate urban morphology at 100-meter resolution, derived from the Open Street Map (OSM) database (Bernard et al., 2022). The latter employs the Open Street Map database to estimate close-to-reality urban geometries, with the help of a random forest technique to estimate missing building heights in the dataset. The comparison with 79  in-situ observations shows that all the simulations are able to currently represent urban air temperature trends for homogeneous areas, such as the Paris city center and compact homogeneous areas. On the other hand, heterogeneous and scattered urban areas temperatures are not well represented by both higher-resolution simulations and the category-based ECOCLIMAP-SG landuse.On the contrary, the OSM-based landuse is sensible to city heterogeneity and horizontal variability. Considering the 100-m simulations, it is clear that category-based land uses are not suitable for very-high-resolution urban canopy layer simulations, since they cannot truly capture the neighborhood-scale variation within the same city.For this reason, it is important, with increasing NWP resolution, to employ suitable landuse datasets, coherent with the employed horizontal resolution and applicable physical parameterizations.
Protocol for a Last Interglacial Antarctic ice-sheet model inter-comparison
Authors: Gregoire Lauren , Menthon Maxence , Gasson Edward , Sime Louise
Published: March 2024

During the last interglacial, geological records show evidence that the sea level peaked between 6 and 9 m above pre-industrial sea level, with a major contribution from the Antarctic ice sheet. However, ice-sheet models give a very large range of values due to a lack of understanding of the mechanisms leading to the Antarctic ice sheet retreat during the Last InterglacialHere, we propose a protocol to apply systematically to multiple ice-sheet models to better understand the climate and ice-sheet model uncertainties as well as mechanisms leading to a smaller Antarctic ice sheet. We present the climate forcing choices and methodology, ice-sheet model requirements and the group of simulations suggested. The protocol includes transient penultimate deglaciation and last interglacial equilibrium simulations to make it accessible to all types of ice-sheet models. The protocol includes also sensitivity experiments such as hosing.Inputs from the community are welcome to improve the protocol under development and make it relevant to all ice-sheet modelling groups interested in participating!
Direct Numerical Simulation of shear turbulence interacting with a melting-freezing ice layer
Authors: Perissutti Diego , Zonta Francesco , Roccon Alessio , Marchioli Cristian , Soldati Alfredo
Published: March 2024

When a turbulent flow of water interacts with an ice boundary at near-freezing temperature, the fluid can undergo freezing or melting, depending on the local temperature. The turbulence structures that develop in proximity to the ice layer can affect the convective heat transport patterns, leading to the formation of complex phase-boundary morphologies. The ice layer evolves as part of the solution and modifies the near-boundary fluid structures, resulting in heat transfer perturbations. We investigate these ice-water interactions at small scales by performing Direct Numerical Simulations of an open channel flow at shear Reynolds number in the range between 10^2 and 10^3. The upper section of the channel is occupied by ice, while free shear conditions are applied at the bottom. Temperature is imposed on both walls. The ice melting/freezing is simulated using a phase field method [1] combined with a volume penalization immersed boundary method. A pseudo-spectral scheme [2] is used to solve the equations for momentum and energy transport and for phase evolution. We investigated how the behavior of the system changes with the flow conditions (i.e. Reynolds number), with a specific focus on characterizing the features of the ice morphology. In particular, we observed a remarkable influence of turbulence intensity on the ice morphology: at low shear Reynolds, the typical streamwise-oriented canyons already reported in similar studies [3] are present. However, at higher shear Reynolds, spanwise instabilities are triggered, making the final ice morphology more complex.FIgure1: Render view from below of the open channel flow at a low Reynolds number. On the top section of the channel, the corrugated ice layer is shown. On the ice boundary, the normalized heat flux passing through it is displayed (high heat flux is shown in red, low heat flux in blue). The local temperature field is reported on the side domain boundaries. The typical streamwise-oriented canyons at the ice interface are visible and the heat flux correlates well with those patterns (the heat flux is higher inside the canyons).[1]R. Yang et al., Morphology evolution of a melting solid layer above its melt heated from below, Journal of Fluid Mechanics, 956, A23, 2023.[2]F Zonta et al., Nusselt number and friction factor in thermally stratified turbulent channel flow under non-Oberbeck–Boussinesq conditions, International journal of heat and fluid flow, 44:489–494, 2013.[3]L. A. Couston et al., Topography generation by melting and freezing in a turbulent shear flow, Journal of Fluid Mechanics, 911, A44, 2021.
State-of-the-art radio tracking data performance of BepiColombo MORE during cruise
Authors: di Stefano Ivan , Cappuccio Paolo , Doria Irene , Iess Luciano
Published: March 2024

The BepiColombo mission, a collaborative venture between ESA and JAXA, started its journey on October 20, 2018, from the Kourou spaceport in French Guiana, with the goal of reaching Mercury by late 2025. During its 7-year cruise phase, BepiColombo encounters eleven superior solar conjunctions, an alignment where the Sun is positioned between the spacecraft and Earth. The Mercury Orbiter Radio Science Experiment (MORE) utilized the first six conjunctions to test gravitational theories by measuring the relativistic time delay and frequency shift of photons as they pass near the Sun. This process involved collecting range and Doppler data from the ESTRACK DSA-3 antenna in Malargue (Argentina) and NASA’s DSS 25 antenna in Goldstone (California). Over 15 radio tracking passes were scheduled for each of the six campaigns (March 2021, February 2022, July 2022, February 2023, July 2023, and December 2023). A comprehensive calibration process, addressing various noise sources, was essential for conducting the general relativity tests.Central to the superior conjunction experiments are the onboard Deep Space Transponder (DST) and the Ka-band transponder (KaT). MORE's KaT establishes a two-way coherent radio link in the Ka-band, enabling both uplink and downlink communications and incorporating a novel 24 Mcps pseudo-noise (PN) modulation. The DST supports two-way coherent X/X and X/Ka Doppler and PN ranging at 3 Mcps. Multi-frequency radio links are crucial for calibrating dispersive noise, primarily from solar corona plasma. This technique has been previously employed in Cassini's cruise radio science experiments, providing plasma-free observations up to a minimum impact parameter of 7 solar radii.Furthermore, the Tropospheric Delay Calibration System (TDCS) at DSA-3 significantly reduces the impact of tropospheric water vapor. The KaT is equipped with a self-calibration loop for measuring the transponder group delay, while the DST relies on pre-flight ground test values. DSA-3's group delay calibration system conducts pre-tracking pass measurements for each link (X/X, X/Ka, Ka/Ka), with continuous in-pass measurements available exclusively for the Ka/Ka link, the primary data source for the radio science experiments.This work presents the performance of calibrated range and Doppler data from DSA-3 across five solar conjunction experiments. We report the spectral properties of the calibrated residuals, highlighting the improvements achieved through calibration procedures. Notably, these campaigns marked the first use of a plasma-cancellation scheme for calibrating range data, proving effective up to an impact parameter of about 4 solar radii. The final accuracy of the radiometric data was  about 0.02 mm/s  at 60-second integration time and ~4.5 cm at 2 s interval, respectively for range rate and range measurements.
Influence of trenches and subway system on pluvial flood forecast 
Authors: Sämann Robert , Treindl Johanna , Fuchs Lothar , Beeneken Thomas , Berkhahn Simon
Published: March 2024

The FURBAS project (Forecasting urban floods and strong rainfall events, 2022-2025) aims at establishing a real-time pluvial flood forecast system for the city of Hanover in Germany with a total catchment area of 260 km². The forecast system consists of radar rainfall with nowcasting  and an Artificial Neuronal Network (ANN) to forecast the dynamical evolution of surface water levels in the city with a spatial resolution of 5x5 meter and a temporal resolution of 5 minutes (Berkhahn & Neuweiler, 2023). The ANN is trained based on results of a physically based hydrodynamic model (HYSTEM EXTRAN 2D) with bi-directional coupled storm-sewer (1d) to surface (2d) domain.The terrain has a slight gradient which causes a long travel time in the sewer system. The pipe network is partially built as combined sewer and separate sewer system. In the latter, rainfall is partially routed via trenches that are modelled as part of the 2d surface. These trenches are required to get an impression of the overall extent of the flooding and the interaction with the sewer system. In classical modelling approaches the drainage volume vanishes when reaching the outlets of the pipe network which leads to an underestimation of the flood level. We show the effects of modelling trenches as elements of the surface and provide tips for the correct arrangement of trenches.The underground transport tunnels of a city are a rarely modelled factor in the flooding of a city. The underground stations are connected to the public drainage system where it can lead to a drainage delay, due to underground storage tanks. Flooding or overload of the drainage pipes along the underground tunnels have an important influence on the operability of the trains because the inflowing water is pumped into the regular drainage network. The fill level of the pipes is therefore the decisive limit value. We show the effects of station entrances and tunnel ramps to the water level at the surface and how the precipitation intensity is decisive for the operation of the trains.Funding:The FURBAS research project is a cooperation of the Institute for Technical and Scientific Hydrology (itwh) GmbH, the Institute of Fluid Mechanics and Environmental Physics in Civil Engineering, Leibniz University of Hanover, and the municipal operation for Hanover city drainage. The project is funded by the German Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection under grand number 67DAS224.Literature: Berkhahn, S., & Neuweiler, I. (2023). Data driven real-time prediction of urban floods with spatial and temporal distribution. Journal of Hydrology X, 100167.
Modeling the transport and residence time of microplastic particles in lakes and reservoirs
Authors: Aizinger Vadym , Jagau Lisa , Gilfedder Benjamin , Fleckenstein Jan
Published: March 2024

Microplastic (MP) particles are assumed to be potentially harmful to organisms in the hydrosphere. To better assess the exposure and the associated risk it is essential to quantify the transport and sedimentation behavior of MP particles in aquatic environments.Using the Delft3D Flexible Mesh Suite we set up a three-dimensional hydrodynamic and MP transport model for lakes and reservoirs. Our focus is on modeling polymers with different densities and particle sizes to identify patterns of particle residence time and sedimentation. The reservoir Großer Brombachsee in Germany serves as the research site with realistic forcings and boundary conditions.We present first results for horizontal and vertical distribution patterns for different polymer types. We found that the distribution of MP in the computational domain is strongly affected by both particle density and particle size. Smaller, lighter particles are spread over the entire horizontal extent of the reservoir, but particles of higher density or of larger size settle within a limited area around the inflow location, indicating a much higher settling velocity.
Continuous 3D modelling over deep time – the SCION Earth Evolution Model
Authors: Mills Benjamin , Zheng Dongyu , Gurung Khushboo , Merdith Andrew , Krause Alexander , Xu Zhen , Bowyer Fred , Hunter Stephen
Published: March 2024

Earth system models for deep time have typically been unable to represent geological timespans in 3D because climate and ocean circulation plays a key role in global biogeochemistry and generating a 3D physical climate simulation is extremely computationally expensive. This means that Earth System Modelling for periods of over 1 Myr has been exclusively carried out in nondimensional box models, which leads to oversimplification of spatially heterogeneous processes like continental weathering and marine carbon burial. This simplification may be a key reason why so many climate questions over deep time remain unresolved. The SCION (Spatial Continuous IntegratiON) project aims to produce a 3D and self-consistent climate and biogeochemical system that can be run over billion-year timeframes. To do this, it employs a physical climate emulator which is developed using a Deep Learning method trained on hundreds of General Circulation Model runs over different paleogeographies and CO2 levels. The SCION development project – SIM-EARTH – also includes a new process-based reconstruction of paleotopography using the GPlates kinematic plate model, development of a long-term dynamic global vegetation module and ocean biogeochemical module, and databasing projects to establish 3D datasets for marine and terrestrial palaeontology and geochemistry that can be compared to model outputs at the local scale to test hypotheses. We hope that new model frameworks like this can help us better understand the evolution of Earth’s surface conditions over time, assess the contribution of the biosphere to global environmental change, and help determine what fundamental characteristics are required for a planet to be habitable for complex life.
Time’s up, bottom-up! A successful bottom-up approach for diversity and inclusions at Utrecht University
Authors: Verberne Manon , Cox Jana R. , Dunn Frances E. , Postma Merel , Venema Tina
Published: March 2024

Young Women of Geoscience (YWOG) is a group of young professionals (PhDs, postdocs, assistant professors and supporting staff) at Utrecht University with the aim to inspire, connect and support women and historically underrepresented groups in the field of geosciences, by creating an equal and inclusive working environment. We do this by opening up conversations and creating a safe and positive space for discussion. Now in our seventh year, the committee has established itself as a constant and stable presence within the faculty with regular events and initiatives that can easily be organized from our reputable base.Our regular events consist of meet-and-greet sessions with senior staff members, that are well-attended by a variety of colleagues, which result in inspiring conversations. Additionally, book give-aways combined with book discussions are a recurring event, where books on diversity, inclusions and climate change are used to open conversations. These events often engage individuals who may not have initially identified with the committee's target audience, but afterwards their interest was sparked. In recent years we also organized successful events due to requests from staff members. Parenting during COVID was a successful online event with a panel discussion consisting of colleagues sharing tips and struggles. Additionally, this year we organized an event on pronouns, reaching a wide audience, from PhDs to supporting staff, professors and the faculty dean. It was also this session, with informative presentations and lively discussion, that led to immediate action from higher level staff on practical matters concerning pronouns in the workplace.Our experience highlights the importance of a bottom-up approach in instigating meaningful change. The pronouns event is a prime example of this, opening the eyes of many attendees and making people feel the urgency for action. The event stemmed from a need within the faculty. However, to be able to organize such an event there must be a platform to do so. We have the opportunity to organize many events helped by funding through an Equality, Diversity and Inclusion (EDI) scheme and an internal award won by the committee. We aim to continue with the regular events like the meet-and-greets and book shares, and hope to organize more events that are based on the needs in the faculty to open conversations. YWOG's experience demonstrates the efficacy of a bottom-up approach, emphasizing the importance of diverse perspectives in fostering substantial changes toward a more inclusive working environment. The committee looks forward to sharing its experiences, connecting with other faculties and universities, and inspiring collective efforts to promote diversity and inclusion within geosciences.
A novel index for forest structure complexity mapping from single multispectral images
Authors: Xu Xin , Tong Xiaowei , Brandt Martin , Yue Yuemin , Mugabowindekwe Maurice , Li Sizhuo , Fensholt Rasmus
Published: March 2024

Due to the provisioning of essential ecosystem goods and services by forests, the monitoring of forests has attracted considerable attention within the academic community. However, the majority of remote sensing studies covering large areas primarily focus on tree cover due to resolution limitations. It is necessary to integrate innovative spatial methods and tools in the monitoring of forest ecosystems. Forest Structure Complexity, representing the spatial heterogeneity within forest structures, plays a pivotal role in influencing ecosystem processes and functions. In this study, we use multi-spectral remote sensing image data to extract the crown information of the single tree through deep learning technology; Subsequently, we analyze the relationship between each single tree and its neighboring trees, and explore the structural characteristics at tree level. Finally, we developed the canopy structural complexity index and applied it to Nordic forests, urban areas, savanna, rainforest, and the most complex tree plantations and natural forests in China Karst. This study aims to gain a deeper understanding of the forest structure complexity in diverse ecosystems and provide valuable information for sustainable forestry management and ecosystem conservation. The method developed in this study eliminates the need  for additional field measurement and radar data, offering robust tool support for extensive and efficient the monitoring of forest structure complexity, which has a wide application prospect.
Exploring Regional-Scale Covariation: Atmospheric CO2 Anomalies Distribution Patterns, Vegetation Spread, and Climate Variables
Authors: Jagadish Buddola , Patra Prabir Kumar , Behera Mukunda Dev
Published: March 2024

The role of the terrestrial biosphere in regulating the global carbon cycle is critical, and it is crucial to comprehend the regional-scale source-sink dynamics and the underlying mechanisms for developing effective mitigation strategies. The present study investigated the dynamic relationship between atmospheric CO2 levels and environmental factors in South Asia (SA), Southeast Asia (SEA) and West Asia (WA); these regions are home to diverse ecosystems, including tropical rainforests, mangroves, and coral reefs. Understanding carbon dynamics in these ecosystems is crucial as they play a significant role in sequestering and storing carbon. Utilizing data from 2015 to 2021 from the OCO-2 satellite, we analyzed the column-averaged dry air mole fraction of atmospheric CO2 (XCO2) along with variables such as precipitation, temperature, and Leaf Area Index (LAI), which distinguishes between high and low vegetation types. These environmental factors were synchronized with the spatial and temporal attributes of bias-corrected Lite (V11) level-2 daily files obtained from OCO-2. The majority of the zones in the area showed a positive relationship between their temperature anomalies and XCO2 anomalies, albeit with varying lag periods (ranging from 0 to 4 months). This suggests that these zones could potentially act as sources of CO2 during warmer periods. This trend was not observed in some regions, including the western plateau and hills, eastern coastal planes and hills, Pakistan, and Nepal, where the relationship between temperature and CO2 exhibited varying lag effects. The correlations were examined between the inter-annual variability (IAV) of detrended and depersonalized monthly-resampled anomalies of XCO2 datasets and various environmental factors (anomalies) across diverse agroclimatic zones. In tropical savannah and humid subtropical climates, observed a positive correlation, between XCO2 anomalies and precipitation whereas arid and semi-arid areas displayed negative correlations. These patterns indicate that increased rainfall in certain regions might enhance vegetation productivity, thereby reducing atmospheric CO2 levels. Furthermore, in areas dominated by tropical aseasonal forests, a dense LAI correlated negatively with XCO2, suggesting that more dense vegetation leads to increased CO2 absorption through photosynthesis. In contrast, tropical seasonal forests showed a positive correlation between LAI and XCO2, each with a unique lag period. Our analysis demonstrates the complex patterns of CO2 anomalies distribution in SA, WA and SEA influenced by climatic factors (precipitation and temperature) and vegetation density (LAI). These insights are crucial for understanding regional CO2 source-sink dynamics and formulating effective climate change mitigation strategies.
Studying the influence of environmental parameters on calving variability at Hansbreen, in Svalbard
Authors: Maniktala Dhruv , Glowacki Oskar
Published: March 2024

The marine-terminating glaciers in Svalbard are retreating and losing mass at an alarming rate due to the rapidly warming climate. And glacier calving is one of the most important process contributing to the glacier mass loss. Hence, it is very important to observe the glacier termini to understand calving variability and the influence of local environmental conditions on them. Here, high frequency time-lapse images have been used to observe the calving front of Hansbreen (a tidewater glacier in the Honrsund fjord, Svalbard) at a 15-minute interval. The time-lapse images have been visually analyzed from April 2016 to October 2016, to observe the calving variability. The calving events are identified and then classified based on several parameters. The environmental parameters like air temperature, sea surface temperature, tidal cycle, water salinity, etc, for the same region have been understood to see if they have any influence spatial and temporal distribution of the observed calving events. [This research has been supported by the National Science Centre, Poland (grant no. 2021/43/D/ST10/00616) and the Ministry of Education and Science, Poland (subsidy for the Institute of Geophysics, Polish Academy of Sciences).]
Fostering an Earthquake Culture: Towards Enhancing Seismic Resilience in Türkiye
Authors: Ertuncay Deniz , Karasözen Ezgi , Büyükakpınar Pınar , Oral Elif , Havazlı Emre
Published: March 2024

The recent M 7.5 earthquake that struck Japan on January 1st, 2024, marked a significant event due to its substantial magnitude and surprisingly minimal damage. This occurrence serves as a stark contrast to Türkiye's experience, notably the devastating Kahramanmaraş earthquake of February 2023. Japan's impressive success in earthquake resilience, achieved through strict building code enforcement and effective public awareness campaigns, stands in sharp contrast to Türkiye's ongoing struggle with seismic vulnerability. This discrepancy underscores the urgent need to bridge the gap between scientific knowledge and societal preparedness in Türkiye.To address this pressing issue, we propose a set of actionable guidelines. Firstly, there is a need to integrate geoscience into Türkiye's educational system, thereby enhancing public understanding of earthquake risks. Simultaneously, opportunities for geoscientists should be expanded to facilitate expertise growth. Establishing local earthquake centers is paramount to improving seismic monitoring, research, and outreach efforts, bolstering the nation's preparedness for seismic events. Furthermore, geoscientists should prioritize science communication training to effectively engage the public and combat misinformation, thereby fostering a more informed and proactive society. In addition to these measures, implementing earthquake scenario modeling and regular preparedness exercises are instrumental in enhancing nationwide earthquake readiness and preparing Türkiye for future seismic events. Lastly, we emphasize the importance of fostering an earthquake culture through memory and awareness initiatives. This approach will instill a collective consciousness about seismic risks and responses, creating a more resilient society.It is essential to recognize that the successful implementation of these guidelines will require active participation from scientists, institutions, and the public. By following these recommendations, Türkiye can build resilience and mitigate the impact of future earthquakes, ultimately ensuring a safer future for its citizens.
Flow focusing associated with doublet operation
Authors: Mumand Fahim , Renner Jörg
Published: March 2024

Heat and cold storage in the subsurface as well as geothermal energy provision intrinsically involve cyclic pumping operations, often in fields of several boreholes. We investigated the pressure and flow-rate fields resulting from the simultaneous periodic operation of two boreholes. The interference in pressure experienced by further (monitoring) boreholes can be assessed by an analytical solution when assuming radial flow from and to the pumping wells. This solution is derived through superposition, relying on the known solution for periodic pumping in a single well. The pressure gradient field, indicative of flow direction, is distorted from radial form, implying dominant flow and consequently heat advection between the two boreholes. We compared the analytical results to observations from field tests conducted in four boreholes located close to the northwestern banks of an artificial freshwater reservoir, the Kemnader See, at the southern city-limits of Bochum, Germany. In the light of the derived solutions, the field observations allow us to assess the role of inhomogeneity and fracture flow for the flow focusing between the pumping wells. Solving and investigating the hydraulic problem constitutes the necessary first step towards devising schemes for the optimization of cold and heat storage or geothermal energy provision by varying the period and phase of pumping coeval operations in several boreholes.
The influence of the PPP-RTK reference station network configuration on position accuracy and real-time performance
Authors: Rost Christian , Riedel Franziska , Freitag Martin , Vennebusch Markus , Winter Vitaly , Stockhaus Timon , Trautvetter Christian , Knöfel Christoph
Published: March 2024

PPP-RTK is a GNSS-based method for absolute positioning in real-time that has gained importance in recent years. Unlike network RTK, correction data can be provided as broadcast to an unlimited number of users.In Germany, a nationwide PPP-RTK service is about to be implemented. The service is being set up in cooperation with the surveying authorities of the federal states and the Bundesamt für Kartographie und Geodäsie (BKG). Two independent computing facilities at BKG and Zentrale Stelle SAPOS® guarantee a high level of reliability of the service. Although both facilities use the GNSS processing software GNSMART, the analysed reference station networks differ. The service is currently being tested with various scenarios and setups. Due to its redundancy, different configurations can be analysed in parallel.  The service performance is monitored in a nationwide monitoring network. Three of these monitoring stations are equipped with two identical receivers that are connected to the same antenna and can be used for detailed comparisons of the two service setups. We present results how the network configuration impacts the service performance with a special focus on the present ionosphere activity.
Complex subduction and mantle dynamics induced by along-strike variations in overriding plate structure
Authors: Gea Jódar Pedro José , Negredo Ana M. , Mancilla Flor de Lis , van Hunen Jeroen , Billen Magali
Published: March 2024

Subduction zones are intrinsically three-dimensional and present a huge variability in observables along the trench, such as deformation style of the overriding plate, trench velocity, slab depth and mantle flow patterns. Geodynamic models commonly rely on factors such as external mantle flow and/or along-strike variations in the properties of subducting slabs to account for these variations in the trench-parallel direction, often ignoring the role of the overriding plate, which has been proven to strongly affect subduction dynamics. In this work, we investigate through self-consistent 3D subduction models how along-strike variations in the overriding plate structure can induce along-strike variations in subduction dynamics and mantle flow. Our results show that variations of the overriding plate thickness along the trench-parallel direction result in large along-strike variations of the trench retreat velocities, leading to highly arcuated trenches. This difference in trench retreat velocities along the trench induce complex mantle flow patterns, with the toroidal flow cells that surround the slab converging below the thin part of the overriding plate. Due to this complex mantle flow, regions of maximum localised extension are found within the thin portion of the overriding plate. Overall, our results contribute to a better understanding of seismic anisotropy observations at subduction zones on Earth.
Assessing the accuracy of GEDI for mapping resilience in the Amazon rainforest along a gradient of disturbance to recovery 
Authors: Doyle Emily , Boulton Chris , Graham Hugh , Lenton Tim , Feldpausch Ted , Cunliffe Andrew
Published: March 2024

Understanding the resilience of tropical vegetation, its ability to recover from disturbance, is fundamental to assess future responses to environmental and climatic fluctuations. The Amazon rainforest has been identified as a potential tipping element in the Earth’s climate system and there is mounting concern over its persistent degradation. Extreme climate events and continued logging, forest fire and fragmentation threaten the Amazon’s structural integrity and its role as a carbon sink, with remotely sensed data providing observational evidence of resilience loss since the early 2000s. Fragmentation and degradation of tropical forest is suggested to slow recovery from perturbations, ensuing a potential to destabilise the rainforest and cause widespread transition from forest to savanna-like ecosystem state.Remotely sensed LiDAR data provides a structural blueprint of forest canopy. The Global Ecosystem Dynamics Investigation (GEDI) spaceborne LiDAR characterises a new era of large-scale forest height quantification, with capabilities to further understand forest structure, and therefore forest response to perturbation across the entire Amazon. Although GEDI’s capabilities have been realised in boreal forest early disturbance monitoring, and to assess growth rates of tropical secondary forest, research thus far is yet to assess its ability to identify tropical forest of various degradation and recovery including logged, burned and fragmented over increasing timescales of recovery. Forest degraded by burning is characterised by different structure than selectively logged, or edge forest, and validating the ability of GEDI to represent these states is essential for identifying alternative forest states.  Here, we investigate the potential of the GEDI LiDAR mission to map tropical forest along a gradient of degradation to recovery. A combination of ground data, MapBiomas secondary forest and burned area products are utilised to classify perturbed forest. We then assess the correspondence of GEDI waveform metrics including relative height and canopy cover, extracted from 2A and 2B products using the newly developed R package ‘chewie’, with airborne LiDAR across the Brazilian Amazon. This research will inform further tropical forest alternative-state study, whilst the assessment of GEDI’s structural capability to represent degraded forest types provides valuable information for forest restoration status to support post-degradation management strategies. 
Devonian paleomagnetism in the West Qinling mountains of China and its tectonic significance
Authors: Chen Yongfa , Dai Shuang , Dekkers Mark , Fu Qiang
Published: March 2024

The Qinling Orogenic Belt (QOB) traverses east-west across the central part of continental China. Being the suturing of the North China Block and the South China Block, it represents a distinctive and typical composite continental orogenic belt that holds a prominent position in the formation and evolution of continental China. As an integral segment of the QOB, the West Qinling was originally formed by the collision of the North China block and the South China block during the Paleozoic and Triassic. It was superimposed by the Mesozoic and Cenozoic intracontinental orogeny. Thus it has undergone a prolonged history of formation and evolution. Devonian strata are central to our understanding of the QOB geology. However, their paleolatitude is currently poorly constrained. Therefore, we conducted a paleomagnetic study on Devonian limestone samples (32 sites, 352 samples) from the West Qinling (34.2°N, 103.1°E). For optimal results, a combination of thermal demagnetization and alternating field demagnetization was employed. In addition, rock magnetic experiments will be executed on a subset of representative samples, including M-T curves, hysteresis loops, and FORCs. About 55% of the samples yield characteristic remanent magnetization (ChRM) directions. The demagnetization curves show two-component characteristics, with the medium and high temperature components tending to the origin (200~500℃), while the remainder unveiled inconsistent ChRM directions. This study aims to reconstruct the paleolatitude of the West Qinling during the Devonian, and to provide new insights into the tectonic evolution of the QOB.
Observations of thunderstorms with a neuromorphic camera: First results of the THOR-DAVIS experiment on the International Space Station.
Authors: Chanrion Olivier , Pedersen Nicolas , Yair Yoav , Stendel Martin , Mogensen Andreas , Li Dongshuai , Stokholm Andreas , Neubert Torsten
Published: March 2024

THOR-DAVIS is an experiment on the International Space Station to observe thunderclouds and their electrical activity with a neuromorphic camera and a co-aligned video camera. A neuromorphic camera, or 'event camera,' only reads pixels when there is a change in pixel illumination, allowing for a temporal resolution that may reach 10 microseconds. Launched by the SpaceX Commercial Resupply Service mission on June 5, 2023, THOR-DAVIS was part of Danish ESA astronaut Andreas Mogensen’s Huginn mission. The scientific focus was to conduct video observations of electrical activity at the cloud tops and the stratosphere above and to extract their altitudes. The technical objective was to test the neuromorphic concept for observations of thunderstorms from space. Andreas Mogensen performed 15 days of observations, passing over 48 thunderstorms, most forecasted by us a day in advance following a procedure inherited from previous ISS experiments (THOR (2015), ILAN-ES (2022)) and some at his own initiative. In all, 36 thunderstorms were recorded in both cameras, totaling ~3 hours of observations. Most notably, Andreas Mogensen secured the first observations of sprites and of an elve with a neuromorphic camera. In addition, numerous lightning flashes, including spider lightning with leader branches extending above the clouds, were observed. The presentation will provide an overview of the THOR-DAVIS payload design, laboratory measurements, and some of the observations from the ISS.
Projection of near-surface winds in Antarctica using ESMs downscaled by a regional atmospheric model (MAR)
Authors: Davrinche Cécile , Agosta Cécile , Amory Charles , Kittel Christoph , Orsi Anaïs
Published: March 2024

Antarctica's climate is unique, partly due to strong westerlies on the ocean and strong easterlies at the ice sheet margins. On the continent, near-surface winds play a major role in shaping the climate of the continent as they influence sea-ice formation, the amount of precipitation reaching the ground or the stability of the boundary layer. They result from both large-scale and surface forcings, whose relative magnitude and future evolution is yet uncertain.We show an evaluation at present day of a selection of Earth System Models (ESMs) from CMIP6 and their downscalings by the regional atmospheric model MAR. The ESMs have been selected based on their demonstrated ability to represent fairly well the southern hemisphere general atmospheric circulation. They are thus expected to have a good representation of the large-scale forcing of near-surface wind. We present a framework for evaluating against field observations how accurately different CMIP6 products are able to represent near-surface winds over Antarctica. We also present the selection process for the automatic weather stations to use and the metrics for the evaluation.Then, we investigate the future evolution of near-surface winds on the Antarctic continent as projected by the ESMs and their downscalings. We show maps of their projected changes up to 2100 and investigate whether these changes are significant with regards to the internal variability of the ESMs and their historical biases. This evaluation provides us with a first step towards characterizing the future evolution of near-surface winds in Antarctica. Further work will then be undertaken to provide a more comprehensive analysis of their potential drivers, including the evolution of both large-scale and surface forcings.
The Pioneering Role of Natural-Occurring Peptides on Methane Hydrate Formation—Insights from Experiments and Numerical Simulations
Authors: Pan Mengdi , Radola Bastien , Allen Christopher C.R. , English Niall J.
Published: March 2024

Methane hydrates are the most abundant clathrates found in the environment, predominantly in the permafrost and marine continental margins. As such, they consitute an energy resource, a concern for climate change, as well as a potentially significant source of carbon for microorganisms. However, relatively little is known about the way that these microorganisms interact, if at all, with methane hydrate deposits in their environment. Recently, a porin produced by a marine methylotroph (Methylophaga aminisulfidivorans) was found to promote hydrate formation in conditions mimicking that of the seafloor. A specific peptide sequence (TAFDGGS) was shown to be at least partially responsible for this behaviour. However, the exact physico-chemical mechanisms underlying such effects are still unclear.Our research employed a dual methodology, integrating experimental procedures with molecular dynamics simulations to answer the question of how naturally occurring peptides can influence methane hydrate formation. Initially, laboratory experiments were conducted to observe the kinetics of methane hydrate formation in the presence of the selected natural peptide (TAFDGGS) and the traditional hydrate promoter: sodium dodecyl sulfate (SDS). Methane hydrate formation from deionized water served as a reference. Parameters such as rate of formation, induction time and total gas consumption were meticulously recorded and analysed. In parallel, molecular dynamics simulations of the hydrate formation process with and without the peptide were carried out. The careful analysis of the interactions between water, methane and the peptide provided molecular-level insights on how peptides can influence the nucleation and growth of methane hydrate clusters. Our results indicate that the natural peptide exhibits a distinctive promoting effect on the formation kinetics of methane hydrates. However, the mechanistic hypothesis that the promotion effect is achieved by providing more nucleation sites was ruled out by comparison with the reference groups. Instead, the results suggest a more complex biocatalytic effect on hydrate kinetics.These findings suggest a potential for peptides as eco-friendly alternatives to traditional chemical promoters in methane hydrate research and provide valuable insights into the design of more efficient and sustainable bio-based promoters. More fundamentally, this study lays a solid foundation for our understanding of the interactions between peptides and hydrates in nature and paves the way for further research on the role of proteins or microorganisms on hydrate deposits.
How to benefit from multi-sensor synergy using open Ocean Virtual Laboratory tools
Authors: Gaultier Lucile , Collard Fabrice , Donlon Craig , El Khoury Hanna Ziad , Herlédan Sylvain , Le Seach Guillaume
Published: March 2024

In the past decade, the emergence of new satellites and sensors has facilitated the observation of a diverse range of oceanic physical variables across various scales. For instance, the Sentinel 1-2-3-6 program encompasses sensors like SAR, Ocean Color, Temperature brightness, or altimeter, each with an individual long revisit time but a rapid revisit from a constellation perspective. Additionally, geostationary sensors such as SEVIRI contribute by providing Infra Red SST every hour, significantly enhancing coverage in cloudy areas. These variables contain crucial information about the ocean's state.Despite the wealth of data, discovering, collocating, and analyzing a heterogeneous dataset can be challenging and act as a barrier for potential users wishing to leverage Earth Observation (EO) data. Accessing low-level data and preparing them for analysis requires a diverse set of skills. Addressing this challenge, the Ocean Virtual Laboratory Next Generation (OVL-NG) project has developed two tools, which will be introduced.Firstly, online data visualization websites, such as https://ovl.oceandatalab.com, have been made publicly accessible. These platforms empower users to explore various satellite, in-situ, and model data with just a few clicks. Users can navigate through time and space, easily compare hundreds of products (some in Near Real-Time), and utilize drawing and annotation features. The OVL web portal also facilitates sharing interesting cases with fellow scientists and communicating about captivating oceanic structures.Secondly, a complementary tool named SEAScope offers additional features for analyzing pre-processed data and user-generated data. SEAScope is a free and open-source standalone application compatible with Windows, Linux, and macOS. It allows users to collocate data in time and space, rendering them on a 3D globe. Users can adjust rendering settings on the fly, extract data over a specific area or transect, and interface with external applications like Jupyter notebooks. This functionality enables users to extract data on a shared grid, analyze them, and import the results back into SEAScope for visualization alongside the input data.                                         The OVL-NG tools will be showcased at the OceanDataLab booth                                  
Advancing Automated Detection in Neutron Scattering Imaging for Improved Root Structure Analysis of Rhizobox-Grown Salix Cuttings
Authors: Eliyahu-Yakir Yahel , Wittwer Mallory , Kaestner Anders , Carminati Andrea , Perona Paolo
Published: March 2024

Abstract:In this work, we present a sequential procedure to analyze non-destructive neutron scattering imaging, which allows to improve the signal-to-noise ratio and maximize the identification of root structure architecture of plant cuttings grown in rhizoboxes containing humid sand sediment.Plant cuttings play a pivotal role in water bioengineering applications, contributing significantly to enhancing waterway ecohydraulic processes, ecomorphodynamic mechanisms, flood protection strategies, and river restoration techniques. Despite their crucial role, various dynamics related to in-channel and bank vegetation responses to hydromechanical forces remain insufficiently understood. In this study, we conducted flume experiments to systematically examine the impact of hydrodynamic forces and subsurface flow on the root structure development of riparian plant cuttings (Salix species). Specifically, we addressed to role of such actions on triggering dynamotropism and hydropatterning mechanisms, which both lead to (upstream) asymmetrical plant root growth and spatially-variable soil reinforcement. The plant cuttings were cultivated in rhizoboxes filled with sand, which did undergo four different treatments aiming at single out which one better controls dynamotropism and hydropatterning. After a 6-week growth period, we employed a Neutron scanner to scan the boxes and detect the intricate root structures non-destructively. Analysis of the scans revealed significant challenges in distinguishing roots from the background due to factors such as the remaining water content at the pore level, sand texture, and variations in root dimensions. The high spatial variability of these parameters significantly influenced the accuracy of root detection. To address these challenges, we have developed a process utilizing advanced tools to enhance the probability of successfully detecting roots within the sand matrix. The automatization of such a procedure will allow to non-destructively analyse a large number of samples for statistically significant correlation analyses.