bluuebunny/crossref_metadata_2025 huggingface dataset:
Rock magnetic signatures reveal the dissociated gas distribution in the gas hydrate reservoir off SW Taiwan
Authors: Huang Yin-Sheng , Horng Chorng-Shern , Su Chih-Chieh , Hsu Shu-Kun , Lin Jing-Yi
Published: February 2023

The first shallow hydrate sample off southwest Taiwan has been collected at core site MD18-3542 in cruise MD214. Attractive features are present at ~5.5 m core depth where an unconformity lies, and sediment properties are distinctively different above and below the layer. In the work, we perform rock magnetic analyses to study the core magnetic behavior, including magnetic susceptibility (MS), hysteresis parameters, and X-ray diffraction spectra. Combining the core features and rock magnetic results with the shallow hydrate formation off southwest Taiwan, we consider that variation of the core magnetic property could relate to the pyritization of magnetic minerals caused by the dissociated gas, and summarize the gas distribution at the shallow strata: Abundant methane with hydrogen sulfide trapped below the unconformity could form an anoxic setting and activate the pyritization. Dissociated gas may have also leaked to its above layer, featuring the MS anomaly at ~3.5 m core depth. Magnetite appears in addition to iron sulfides at the depth between ~6.5 and ~10.0 m, indicating a transition layer and implying the insufficiency of the dissociated gas to complete the pyritization. Iron sulfides become dominant again at the core bottom, revealing that the dissociated gas mainly migrates from deep strata.
High debit sampling of airborne micro and nanoplastics in remote sea
Authors: Eyheraguibel Boris , Ter Halle Alexandra , Ourmieres Yann , Ghiglione Jean-Francois , Amato Pierre
Published: February 2023

The occurrence of micro and nano plastics has been reported in every environmental compartment including marine and freshwaters, soils and sediments, air and atmospheric precipitations.  Recent evidence showing the presence of airborne microplastics in remote ecosystems highlights the extent of this pollution. The atmospheric transportation and the distribution of airborne microplastics still need to be better documented to understand the dynamic of microplastic transfer between ecosystems.While most studies dedicated to the analysis of microplastics in the air use a passive sampling methodology through atmospheric deposition we developed an original stainless device to sample large volumes of air with high debit (2000 L/min) providing a fast sampling of aerosols within a small localized area. An optimized sampling protocol has been deployed in the North Western Mediterranean Sea from the Expedition 7th Continent (E7C) boat. 19 sampling sites have been studied during the E7C expedition in September-October 2019, including measurements in port and coastal areas as well as offshore environments. The analysis of micro/nano plastics was carried out using pyrolysis coupled with gas chromatography and tandem mass spectrometry (Py-GC-MS/MS). This approach allowed us to evaluate the concentrations of micro and nano plastics present in the samples for 5 types of plastics (polypropylene, polystyrene, polymethyl methacrylate, polyethylene terephthalate and polycarbonate) and for 2 size ranges (5-50μm and <5μm).This study confirmed that plastic particles are present in the atmosphere even in remote areas such as the offshore environments. The results showed that airborne micro and nano plastics were detected at each sampling station, from the coast to the open sea, at various concentrations. Py-GC-MS/MS analysis allowed us to quantify the 5 types of polymer and revealed the predominance of PET and PP material. High-volume samplers and  Py-GC-MS/MS analysis have proven to be an efficient and powerful methodology to gather and quantify airborne plastic particles at micro and nanoscale level.
Forecast of Particle Spreading Using Machine Learning in a Complex Multiple-Inlet Coastal System
Authors: Fajardo-Urbina Jeancarlo M. , Liu Yang , Gräwe Ulf , Georgievska Sonja , Grootes Meiert W. , Clercx Herman J.H. , Gerkema Theo , Duran-Matute Matias
Published: February 2023

The implementation of continuous operational forecast systems using numerical models for coastal environments are scarce, computationally expensive, and difficult to maintain. As an alternative, computationally cheaper tools such as machine learning models can be employed. This is especially relevant when the time to produce a forecast is paramount like in oil spills, marine litter spread due to container-ship accidents, and search and rescue operations. Working in this direction, we tested the skill of an advanced deep learning model, namely a convolutional long short-term memory network (ConvLSTM), to predict the Lagrangian advection (the displacement vector of the center of mass) and the dispersion (the spread described by a covariance matrix) of patches of passive tracers. This model was trained with data from a realistic numerical simulation of the Dutch Wadden Sea: a multiple-inlet system of great ecological importance. Using the relevant drivers (wind, tidal amplitude, and atmospheric pressure), the model was set to learn the advection and dispersion after one tidal period of clouds of particles released on a 200 x 200 m grid, covering the entire DWS. Our results show that the model learned the system-wide temporal variability of both advection and dispersion, while the local spatial features were better reproduced for advection than for dispersion. We use the predicted advection and dispersion as inputs to a set of stochastic differential equations for the reconstruction of particle trajectories, as it is commonly done in particle tracking applications that employ diffusion instead of dispersion. We were able to predict the temporal evolution over several tidal periods of particle patches released from specific locations under contrasting cases like calm and stormy conditions. Our method was employed to predict only the horizontal spreading, but it can be extended to predict the 3D evolution of the particle clouds. Finally, our approach requires simulation data and relevant drivers (e.g. atmospheric forcing and tidal amplitudes) for training and the same drivers from any typical forecast systems for forecasting the evolution of particle patches, which makes it a promising operational tool.
A new prewhitening approach for trend analysis in the autocorrelated time series.
Authors: Sheoran Rahul , Dumka Umesh C.
Published: February 2023

In combination with Sen's slope, the non-parametric Mann–Kendall (MK) test is one of the most often used statistical techniques for determining a time series' trends. A serially uncorrelated time series is required for the MK test since the autocorrelation in the dataset seriously affects the type 1 and type 2 errors and reduces the performance of the MK test in detecting the statically significant trend. To mitigate this problem, numerous prewhitening techniques (PW, PW-Cor, TFPW-Y, TFPW-WS, VCTFPW; See Collaud Coen et al., 2020) have been developed that effectively reduce lag-1 autocorrelation. In this work, we have proposed a new prewhitening scheme (named as TFPW-Mod) and compared it with previous prewhitening schemes by constructing 5000 linear-trend superimposed (β) AR1 time series with lag-1 autocorrelation (ρ1) using Monte Carlo simulation. We found that the new prewhitening approach keeps a very good balance between maintaining a low number of type 1 and type 2 errors. The results show that the occurrence of both types of errors largely depends on the length of the time series, with longer periods leading to a strong reduction of errors and to lower bias in the trend slope estimation. For weaker trends and/or the low number of samples, TFPW-Mod couldn’t restore the power of test. However, for a strong trend, this method yields the strongest power, almost independent of the lag-1 autocorrelation. The slope estimation of TFPW-Mod is robust for lower/Medium ρ1, but significantly deviates from the original trend for highly correlated time series. In most cases, βTFPW-Mod has lower RMSEs than βVCTFPW, and leads to the unbiased slope estimation with better accuracy.
Climate Information Services for smallholder farmers in the global South
Authors: Paparrizos Spyridon , Sutanto Samuel , Kumar Uthpal , Kranjac-Berisavljevic Gordana , Ludwig Fulco
Published: February 2023

Rural households and farming communities in developing economies of the global South are increasingly developing their agricultural operations and are becoming more (urban) market oriented. Growing higher value crops is essential for their further development. However, climate and weather-related risks are also growing which reduces farming productivity. A vital adaptation strategy is to become better informed about weather and climate variability and change.

Planning of farming activities (e.g. choice of crops, planting date, irrigation, pesticide and fertilizer application, etc.) in many developing countries, used to rely on experiential knowledge of climatic patterns and weather variability. Farmers used to possess knowledge on, for example, when the first rains arrive and how much water is likely to become available and when to expect floods. However, increased hydro-climatic variability as a result of climate change makes farmer predictions increasingly uncertain and farmers are threatened by extreme conditions resulting in crop failure, pest and disease outbreak.

Participatory climate information services can reduce these uncertainties and support farm activities. It can offset climate change impacts, increase adaptive capacity of local vulnerable farmers, unlock their farm potential and build resilient and sustainable farming systems in developing areas of the global South.
Achieving Sustainable Groundwater Development with Effective Measures in Beijing Plain, China
Authors: Liu Sida , Zhou Yangxiao , Eiman Fatima , McClain Michael , Wang Xu-Sheng
Published: February 2023

Intensive groundwater exploitation has depleted groundwater storage and led to a series of geo-environmental problems in Beijing Plain, China. To cope with the groundwater depletion problem and achieve sustainable groundwater development, groundwater abstraction has been reduced and Managed Aquifer Recharge (MAR) and Environmental Flow Release (EFR) projects have been piloted and planned. To evaluate the effectiveness of the proposed measures in restoring groundwater storage depletion in Beijing Plain, a 3D transient groundwater was constructed to simulate the effects of these proposed measures regionally and locally. Results show that with the reduction of groundwater abstraction, the declining trend of groundwater level has been stopped. The implementation of MAR and EFR projects have successfully enhanced the groundwater recharge and restored the connectivity of the surface water and groundwater. Prediction model results also show that with the large-scale MAR implementation and current level of groundwater abstraction, groundwater levels and groundwater storage will slowly increase in the next 30 years. With these combined measures in Beijing Plain, sustainable development of groundwater resources is expected to be achieved in the near future.
Monitoring ionospheric gradients using SWARM satellite data
Authors: Hoque M. Mainul , Jakowski Norbert , Cahuasqui Llerena Juan Andres , Buchert Stephan C. , Kriegel Martin , David Paul , Vasylyev Dmytro , Berdermann Jens , Nielsen Klaus
Published: February 2023

The Swarm data products are well-suited to address a number of crucial topics for space weather science and monitoring, such as investigating spatial and temporal characteristics of ionospheric irregularities or improving topside approaches in ionospheric models for monitoring and forecasting the dynamics of the geo-plasma environment. Precision and safety of life applications using trans-ionospheric signals require key information on space weather conditions in particular on the perturbation degree of the ionosphere. Such applications are particularly vulnerable against severe spatial gradients and rapid changes of the electron density (Ne) as well as the total electron content (TEC) measured along different satellite‐receiver links. Here, we propose two new Swarm products 1) the TEC Gradient Ionosphere indeX (TEGIX) and 2) the Ne Gradient Ionosphere indeX (NEGIX). The TEGIX estimates spatial TEC gradients in the topside ionosphere (Swarm up to GNSS orbit) using GNSS Precise Orbit Determination (POD) measurements whereas the NEGIX estimates spatial Ne gradients using Swarm onboard Langmuir probe (LP) measurements (2 Hz sampled).  The approach takes benefit from the coordinated flight of satellites A and C at an orbit height of about 460 km. We will present a first version of both products and will explore their potential impact, utility, and use through case studies.Acknowledgement:The work is funded by the MIGRAS (Monitoring of Ionospheric Gradients At SWARM) project under the Swarm DISC Subcontract Doc. no: SW‐CO‐DTU‐GS‐133, Rev: 1.
Why is there a systematic bias in the Asian Monsoon in the Met Office Unified Model?
Authors: Furtado Kalli , Martin Gill , Sexton David , Rostron John , Field Paul
Published: February 2023

Many global-climate models have substantial biases in their predictions of the Asian monsoon. For example, the Met Office Unified Model predicts a  monsoon trough that is too zonal and therefore underestimates summer rainfall over south and east Asia. These errors have persisted over many cycles of research-to-operations, and appear robust to significant developments in all major parametrizations in the model. Here, we address a simple question: why are these biases systematic? That is, why have they not been removed by optimization of parameters in the model's physics? Using a Perturbed Parameter Ensemble of AMIP simulations, we show that a strong constraint exists which prevents the Unified Model from simultaneously producing an unbiased monsoon and unbiased global top-of-atmosphere radiation fluxes. We use this constraint to define a scalar parameter, the "structural bias"  of the ensemble, the magnitude of which measures the conflict between the constraints and therefore how "untunable" the model is. We identify the drivers of this parameter, show that it is related to an inability to independently affect the properties of tropical and extra-tropical clouds, and suggest ways in which it could be reduced in future model versions.
Hydrocarbon plays of the Antarctic Peninsula margin: Determining fluid flow pathways
Authors: Arasanz Raquel , Urgeles Roger , León Ricardo , F. Pérez Lara , García Xavier , Bartolomé Rafael
Published: February 2023

The continental margin off the Antarctic Peninsula hosts significant gas hydrates accumulations off the South Shetland Islands. The area has experienced remarkable isostatic rebound due to ice sheet retreat since the Last Glacial Maximum (LGM). Considering heat flow data reported in the area, hydrates could undergone active dissociation. Such dissociation may modify the mechanical properties of hydrate bearing sediments, eventually leading to slope failures and related fluid seepage may also translate in methane emissions to the ocean. Here we use legacy seismic data to map the occurrence of gas hydrates and free gas and their relation to tectonic structures with the aim of determining the nature of fluid emissions (diffuse or focused).The subduction of the former Phoenix plate beneath the Shetland plate is the main tectonic control of the area. Normal faults are particularly apparent in the upper part of the slope. These faults disrupt the seafloor or the upper subsurface (within 0.25 to 1 s TWTT below seafloor).Seismic indicators related to the presence of marine gas hydrates, referred to as bottom simulator reflectors (BSRs), have been observed in the continental slope between Snow and Greenwich Islands and among the Shackleton Fracture Zone and Nelson Island. They are located at water depths between 450 and 4800 m and 0.12 to 0.9 s TWTT below seafloor, becoming shallower towards the shelf edge.  The BSRs are commonly affected by normal faults.In seismic data, free gas is inferred by acoustic blanking and chimneys. However, the same acoustic response could result from intense tectonic activity, particularly at the foot of the slope, where the Shetland block overthrusts the Phoenix plate. Acoustic blanking and seismic chimneys are often found on the slope in water depths between 590 to 5175m and 0 to 2 s TWTT below seafloor. In general the acoustic blanking is identified in the upper part of the sedimentary record, particularly in the accretionary prism. In most seismic profiles, BSRs occur together with faults, chimneys and acoustic blanking.According to our results, faulting plays a significant role in the migration of fluids trapped in the sedimentary record. In addition, the presence of chimneys and acoustic blanking in replacement of BSRs suggests unstable gas hydrates under the present-day Pressure/Temperature conditions.
Assessment of preselected Satellites and Reanalysis Precipitation Products using ground observations over the Upper and the Middle Drâa catchment, central-east of Morocco.
Authors: Khettouch Athmane , Hssaisoune Mohammed , Hermans Thomas , Aouijil Aziz , Bouchaou Lhoussaine
Published: February 2023

In most ungauged areas, validation of precipitation gridded satellite products is fundamental to provide precipitation information with high accuracy and spatial-temporal resolution. Drâa river basin (DRB) in southeastern Morocco is one of ten driest watersheds worldwide with a limited network of rain-measured stations. However, literatures investigations have shown the necessity of strong climatic datasets to conduct water resources management. In this study, five satellite precipitation products with high spatio-temporal resolution were evaluated including: the latest version of Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS V2.0), the atmospheric reanalysis dataset for the global climate by the ECMWF (ERA5-Land), the latest version of Multi-Source Weighted-Ensemble Precipitation (MSWEP V2.2), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Cloud Classification System-Climate Data Record (PERSIANN-CCS-CDR) and Tropical Applications of Meteorology using SATellite data and ground-based observations (TAMSAT V3.1). The evaluation was conducted in terms of their performance in capturing occurred precipitation events and reliable amounts. The Monthly and seasonal precipitation amounts determined by these products at different altitude levels were evaluated against available rain gauge observations for a period of 81 months using point-to-pixel method and with reference to continuous, categorical and volumetrics indices. The only available station belonging to SYNOP weather network (Surface Synoptic Observations) with more than 40 years of data was included to advance our conclusion regarding the performance of a given P-dataset. The achieved results show that the best performance was obtained for ERA5-Land and MSWEP V2.2 for monthly and seasonal time-step, respectively, while CHIRPS V2.0 followed by TAMSAT V3.1 and PERSIANN-CCS-CDR perform the worst. The expected results will cover the performance of each P-dataset for different sub-seasons, elevation, intensities and their ability to detect extreme rain events. The outcomes of this investigation provide valuable information in one of the most scarcely gauged and arid Moroccan watersheds, indicating which P-dataset could be an alternative to rain gauges measurement.Key words: Drâa river basin (DRB), ungauged arid areas, precipitation satellite products, ground observations. 
The 1531-1540 dry summers in Europe - Identifying potential drivers of decadal dry spells using climate reconstructions and ensemble simulations of the past 600 years
Authors: Hövel Laura , Hand Ralf , Franke Jörg , Brönnimann Stefan
Published: February 2023

The decade 1531-1540 was characterized by a high number of dry summer episodes making it the driest summer decade of the past 500 years in some areas of Central Europe. In addition to established climate reconstructions, we use the ModE-RA (Modern Era Reanalysis) and ModE-Sim (Modern Era Simulations) data sets which provide gridded climate information of the past 600 years to analyse the summers of 1531-1540 and compare it with other decadal dry spells over Europe.While most previous studies focus on the variability of individual drought events or multi-decadal mega droughts, our aim is to identify decadal scale dry spells similar to the 1531-1540 decade. With our three-dimensional reanalysis and the model simulations forced with observed volcanic forcings and prescribed SST we can then investigate the atmospheric and oceanic drivers of such events as well as the influence of the volcanic forcings.Our first results show that the magnitude and distribution of observed decadal dry spells in ModE-RA is realistic and comparable to other climate reconstructions. In the ModE-Sim ensemble mean the drying signal for the 1531-1540 event is less strong but still visible. Overall, with our ongoing analysis we contribute to the evaluation of past and future decadal dry spells over Europe that are driven by both natural and anthropogenic forcings.
Formation and identification of Kelvin-Helmholtz generated vortices at Earths magnetopause: Insight from adapting hydrodynamic techniques for MHD
Authors: Kelly Harley , Archer Martin , Eggington Joseph , Heyns Mike , Southwood David , Desai Ravindra , Eastwood Jonathan , Mejnertsen Lars , Chittenden Jeremy
Published: February 2023

The Kelvin-Helmholtz Instability (KHI) plays a significant role in the viscous-like mass, momentum, and energy transfer from the solar wind into the magnetosphere through both vortical and wave dynamics. To confidently study and compare the effects of these dynamics, we must formally define a vortex. Previously, a definition did not exist for the magnetohydrodynamic (MHD) regime. Consequently, we have developed a novel vortex definition (the `λMHD definition’) for MHD flows. This is based on adapting well-used hydrodynamic techniques (the λ2 family of methods) that defines a vortex as a local minimum in an adapted pressure field. We derive the MHD suitable adapted pressure field from the ideal MHD Cauchy-Momentum equation, and find that it is composed of four components. The first three components represent the hydrodynamic properties of rotational momentum flow, density inhomogeneity, and fluid compressibility respectively. The final component makes the λMHD definition unique from hydrodynamics as it represents the rotational component of the J×B Lorentz force which is found using a Helmholtz decomposition. We use the Gorgon global 3-Dimensional MHD code to validate the λMHD vortex definition within a northward IMF simulation run exhibiting KHI-driven waves at the magnetopause flanks. Comparison of λMHD with existing hydrodynamic definitions shows good correlations and skill scores, particularly with the more advanced methods. Our analysis also reveals that the rotational momentum flow term dominates at the magnetopause. The other components provide typically small corrections to this. We have found that at the magnetopause, compressibility generally acts in opposition to the existence of a pressure minimum and thus a vortex. Alternatively, inhomogeneity and the rotational component of the Lorentz force generally act to support the pressure minimum. We explore potential physical reasons for these results and discuss potential applications of this method to further simulation and spacecraft observations.
Hydrological evaluation of the CryoSat-2 Thematic Data Products for inland water monitoring
Authors: Tarpanelli Angelica , Camici Stefania , Renou Julien
Published: February 2023

The monitoring of fresh water is fundamental for political, environmental and economic reasons. The use of satellite altimetry to measure water height is a well-established technique that has advanced over the past three decades. Unlike other repeated orbit missions, CryoSat-2, a Synthetic Aperture Radar satellite launched in 2010 by the European Space Agency, adopts a long repetitive (369 days) drift orbit with the advantages of having short distance between tracks and high spatial coverage.Here, we present the hydrological evaluation of the CryoSat-2 product provided by the ESA Cryo-TEMPO project as a Thematic Data Product. This TDP is an improved version of the CryoSat-2 product as it is specifically dedicated to the inland water theme for non-expert users. The analysis focuses on the evaluation of the water height products based on three retrackers (MLE4, OCOG, TFMRA) during a 10-year period and considering the three different acquisition modes of the CryoSat-2 radar instrument (LRM, SAR and SARin). The study areas are related to two Italian rivers, the Po and the Tiber River, with different characteristics. Results of the validation phase are presented referring to the comparison against ground recorded water level for selected stations over the two rivers. Moreover, the analysis includes the evaluation of the capability of the TDP to fulfil user requirements and to respond adequately to the scientific questions related to 1) flood prediction and forecasting activities, 2) water management demand and supply and 3) climate analysis.
Bipolar volcanic ice-core synchronization of the last glacial cycle
Authors: Svensson Anders ,   Bipolar volcano team
Published: February 2023

Precise synchronization of climate records is essential for deducing the dynamics of the climate system. Ice cores from the Greenland and Antarctic ice sheets have previously been synchronized by the use of cosmogenic isotopes, gas concentrations, and traces of large volcanic eruptions. Identification of identical sequences of volcanic sulfate depositions at both poles have been applied to synchronize ice cores in the Holocene, in the last deglaciation, in Marine Isotope Stage 3 (MIS3) and around the Indonesian Toba eruption occurring close to 74 ka. We now extend this inter-hemispheric volcanic synchronization approach to also cover MIS2 (16.5-24.5 ka BP), MIS4 and part of MIS5 (60-110 ka BP) allowing for a precise bipolar synchronization of the entire last glacial period. The synchronization is based on some 250 volcanic eruptions that are identified as acidity spikes in both Greenland and Antarctica. Similar to previous work, the identification of volcanic sequences at the two poles is supported by annual layer counting in both Greenland and Antarctica, although the identification of annual layers becomes increasingly difficult with depth. To support the synchronization we investigate the deduced annual layer thicknesses (not requiring layer counting) and the inferred depth-depth relation between synchronized ice cores. The precise bipolar synchronization allows to determine the exact inter-hemispheric phasing of abrupt climate change during the last glacial, and to investigate a possible relation between abrupt climate change and volcanism. Furthermore, the frequency and magnitude of large volcanic eruptions of the last glacial can be established.
The riparian zone as a gatekeeper for subsurface stormflow
Authors: Kuleshov Alexey , Hartmann Anne , Blume Theresa , Hopp Maria-Luisa
Published: February 2023

Subsurface stormflow (SSF) can be a major streamflow generation process in small catchments. It is known that SSF generated on the hillslopes of the catchment may change both in its chemical and quantitative composition on the way to the stream. This occurs primarily due to processes in the riparian zone. The riparian zone plays the role of a "reactor" where mixing, storage, and biogeochemical transformation of the hillslope SSF composition occurs.  However, we still lack a comprehensive understanding of this “gatekeeper function” of the riparian zone, controlling the timing and spatial patterns of connectivity and the chemistry of the water being transferred from the hillslopes into the stream.In our study we aim to investigate the SSF signal transformation in the riparian zone. We installed three “dual-use trenches” per catchment in four different catchments located in Germany and Austria. With this novel dual-use trench approach we are able to measure hillslope SSF as well as inject tracer into the riparian zone. We measure response dynamics, timing, flow volumes and chemistry at the upslope side of the trench. We will identify tracers or tracer combinations that characterize SSF and can be used to identify hillslope SSF in riparian zone groundwater and stream flow. The inter-comparison of the four different catchments allows us to evaluate the influence of landscape and climate characteristics. We then use tracer injections at the downslope side of the dual-use trench in combination with an array of shallow groundwater observation wells downslope of the trench to investigate the physical and chemical transformation of hillslope SSF in the riparian zone. This array of wells extends both upstream and downstream of the trench, enabling us to trace the transformation of the uninterrupted physical and chemical signal of SSF on the adjacent hillslopes on its passage to the stream and to evaluate the influence of parafluvial flow.Here, we present first data on tracer concentrations in hillslope SSF and riparian zone groundwater from our test catchments. Ultimately, we aim to develop a conceptual matrix, by which it will be possible to estimate the degree of SSF transformation in the riparian zone, depending on watershed characteristics (topography, soil depth and soil hydraulic properties) and hydrological conditions (antecedent wetness of the watershed and seasonal dynamics).
B2G4: A synthetic data pipeline for the integration of Blender models in Geant4 simulation toolkit.
Authors: Bueno Angel , Sattler Felix , Perez Prada Maximilian , Stephan Maurice , Barnes Sarah
Published: February 2023

Particle simulation software is essential for the development and validation of theoretical prototypes in a myriad of physical appplications. The Geant4 simulation toolkit provides precise particle transport and matter interaction simulations in a controlled setting. The interpretation of simulated results is intimately linked to the level of detail represented in the simulation itself, including the ability of the simulation framework to create detailed geometries. Yet, rendering such highly detailed geometries is a daunting task in Geant4, where high-variance scenes must often be manually coded. Potential geometrical errors increase the time required for this coding procedure, and thus in-depth knowledge of the underlying simulation engine in Geant4 is needed.This research proposes Blender2Geant4 (B2G4), a novel framework which transplants 3D scenes from Blender into Geant4 for synthetic data generation. This was achieved by synergizing the descriptive 3D modelling tools in Blender with the simulation capabilities of Geant4. The ability to import, arrange, and manipulate 3D objects in Blender permits the creation of highly detailed and varied scenes: users can easily create sophisticated geometries by using drag-and-drop placement, shape variance randomization, and intuitive material assignments. The suite of functionalities defined in B2G4 lexically translates geometry facets from Blender into a readable format for Geant4, enabling the automated export and import of scenes with minimal manual input. Hence, the B2G4 framework enables automated mass production of corrected 3D scene variations with precise annotations and geometrical consistency checks. The B2G4 framework is designed as an all-purpose geometry creation interface to reduce the complexity of simulation scenes in Geant4 for a variety of physical applications. The applicability of B2G4 in a muon tomography setup is highlighted with a set of procedurally generated 3D scenes.
Snow evolution through the Last Interglacial with a multi-layer snow model
Authors: Hoang Thi Khanh Dieu , Quiquet Aurélien , Dumas Christophe , Roche Didier M.
Published: February 2023

The Last Interglacial period (LIG), which occurred approximately between 130 and 116 kyr BP, is characterized by similar/warmer temperatures and higher sea levels compared to the present-day conditions due to the orbital variation of the Earth. Hence, the period provides insights into the behavior of the Earth's system components under stable and prolonged warm climates and their subsequent evolution into a glacial state. To better understand the ice sheet's surface mass balance that ultimately drives the advance and retreat of ice-sheets, we study the snow cover changes in the Northern Hemisphere during the LIG. In order to do so, we used BESSI (BErgen Snow Simulator), a physical energy balance model with 15 vertical snow layers and high computational efficiency, to simulate the snowpack evolution. First, BESSI was validated using the regional climate model MAR (Modèle Atmosphérique Régional) as forcing and benchmark for snow cover over the Greenland and Antarctica Ice Sheets under present-day climate. Using two distinct ice sheet climates helps constrain the different processes in place (e.g., albedo and surface melt for Greenland and sublimation for Antarctica). For the LIG simulations, the latest version of an Earth system model of intermediate complexity iLOVECLIM was used to force BESSI in different time slices to fully capture the snow evolution in the Northern Hemisphere throughout this period. Impacts of the downscaling component of iLOVECLIM, which provides higher resolution data and accounts for the influences of the topography, on BESSI performance are also discussed.  The results show that BESSI performs well compared to MAR for the present-day climate, even with a less complex model set-up. Through the LIG, with the ability to model the snow compaction, the change of snow density and snow depth, BESSI simulates the snow cover evolution in the studied area better than the simple snow model (bucket model) included in iLOVECLIM. The findings suggest that BESSI can provide a more physical surface mass balance scheme to ice sheet models such as GRISLI of iLOVECLIM to improve simulations of the ice sheet - climate interactions.  
Revisit the solar wind deceleration upstream of the Martian bow shock based on MAVEN observations
Authors: Liu Yuqi , Liu Kaijun , Hui Huang , Lu Ducheng
Published: February 2023

The solar wind deceleration upstream of the Martian bow shock is examined using particle and magnetic field measurements obtained by Mars Atmosphere and Volatile Evolution (MAVEN). Mars lacks a strong intrinsic magnetic field so its upper atmosphere extends beyond the Martian bow shock and interacts directly with the solar wind. Neutral atoms in the Martian upper atmosphere can be ionized through several physical processes and then start to move with the solar wind flow to form pickup ions. In return, the solar wind is expected to slow down due to the momentum transfer to the pickup ions. The present study surveys the MAVEN solar wind measurements between 2015 and 2019 to evaluate the solar wind deceleration upstream of the Martian bow shock. Different than the previous studies of solar wind deceleration, our analysis carefully excludes the solar wind deceleration in the shock magnetic foot region. The average solar wind deceleration calculated is about 0.7% of the upstream solar wind speed, much smaller than the values given by the previous studies. Further calculation using several reasonable Martian upper atmosphere profiles demonstrates that the deceleration observed is consistent with the pickup ion mass loading scenario.
The Multi-Channel Maximum-Likelihood (MCML) method: towards a multisource detection and wave parameter estimations using deep learning
Authors: Poste Benjamin , Charbit Maurice , Janela Cameijo Alice , Le Pichon Alexis , Listowski Constantino , Roueff François , Vergoz Julien
Published: February 2023

We present an improvement of the Multi-Channel Maximum-Likelihood (MCML) method [1]. This approach is based on the likelihood function derived from a multi-sensor stochastic model expressed in different frequency channels. Using the likelihood function, we determine, for the detection problem, the Generalized Likelihood Ratio (GLR) with a p-value threshold to discriminate signal of interest and noise. For the estimation of the slowness vector, we determine the Maximum Likelihood Estimation (MLE). Comparisons with synthetic and real datasets show that MCML, when implemented in the time-frequency domain, outperforms state-of-the-art detection algorithms in terms of detection probability and false alarm rate in poor signal-to-noise ratio scenarios. We evaluate the capability of MCML to detect overlapping coherent signals in the same time frequency domain, depending on various scenarios with varying signal-to-noise ratio (SNR), frequency bands and array geometry. We quantify the performance of deep learning method to discriminate between interfering coherent signals by predicting the number of sources in a given time-frequency cell using synthetics and real data recorded by stations part of the International Monitoring System (IMS). [1] B Poste, M Charbit, A Le Pichon, C Listowski, F Roueff, J Vergoz (2022), The Multi-Channel Maximum-Likelihood (MCML) method: a new approach for infrasound detection and wave parameter estimation, Geophysical Journal International, https://doi.org/10.1093/gji/ggac377
Interplay between Primary and Secondary Ice Production (SIP) in Arctic Mixed-Phase Clouds (MPCs) as simulated for the M-PACE campaign in ICON
Authors: Possner Anna , Pfannkuch Kevin , Ramadoss Veeramanikandan
Published: February 2023

Recent experiments and modelling studies suggest that secondary ice production (SIP) may close the gap between observed Arctic ice nucleating particle (INP) concentrations and ice crystal number concentrations (Ni). Here we explore model sensitivities with respect to the complexity of different INP parameterisations in numerical simulations under the premiss that Ni is governed by SIP. Idealised, cloud-resolving simulations are performed for the marine cold air outbreak cloud deck sampled during M-PACE (cloud-top temperature of -17°C) with the ICOsahedral Nonhydrostatic (ICON) model.Droplet shattering (DS) of rain drops according to Phillips et al. (2018), and collisional breakup (CB) (Phillips et al. 2017) were implemented and tested in addition to the existing Hallet-Mossop (HM) rime splintering implemented in ICON’s state-of-the-art two-moment bulk microphysics scheme. Furthermore, a fully prognostic temperature-dependent budget representation of INP (Solomon et al. 2015) was implemented and contrasted to a less sophisticated time-relaxation formulation of atmospheric INP concentrations.Overall, 16 different model experiments (24h runs) were performed and analysed. Despite the considerable amount of uncertainty remaining with regard to ice production mechanisms and their process representation in numerical models we conclude from these experiments that: (i) Ni-enhancement through SIP can close the gap between measured and simulated Ni concentrations during M-PACE in ICON consistent with previous studies (e.g. Sotiropoulou et al. 2020; Zhao et al. 2021), (ii) only simulations where DS dominates the SIP signal (potentially amplified by CB) capture the vertical Ni in-cloud profile correctly, (iii) INP recycling remains necessary for MPC maintenance during M-PACE even if Ni is dominated by SIP, and (iv) experiments using a computationally more efficient relaxation-based prognostic parameterisation of primary nucleation are statistically invariant from simulations considering a prognostic INP budget.
Benthic foraminiferal response to the paleoenvironmental changes during the Late Cretaceous Oceanic Anoxic Event 2 at Clot Chevalier (Vocontian Basin, SE France)
Authors: Amaglio Giulia , Petrizzo Maria Rose , Holbourn Ann , Kuhnt Wolfgang , Wolfgring Erik
Published: February 2023

The Cenomanian-Turonian boundary interval is characterized by environmental perturbations related to the Oceanic Anoxic Event 2 (OAE 2), affecting marine biota, including benthic and planktonic foraminifera. This study shows a continuous record of benthic foraminifera that, together with published planktonic foraminiferal and geochemical data, allow to interpret the paleoceanographic changes in surface and bottom waters across the OAE 2 interval in the Clot Chevalier section (Vocontian Basin, SE France). The Clot Chevalier section is located at an outer shelf-upper bathyal environment according to benthic foraminifera, and their composition and abundance changes allow the identification of seven distinct faunal intervals. Below the OAE 2 (middle Cenomanian), the seafloor shows moderately oxic conditions and oligotrophic regimes suggested by high species diversity and abundance of infaunal and epifaunal taxa. Within the OAE 2 (upper Cenomanian), characterized by the highest values of Total Organic Carbon (TOC), the benthic calcareous taxa (Gavelinella sp., Gyroidinoides sp., Praebulimina elata, Tappanina laciniosa) are abundant and radiolaria dominate the microfossil assemblages (> 50%) suggesting eutrophy and suboxic conditions at the seafloor. The lowest part of the OAE 2 shows high abundance of the benthic agglutinated taxa Ammobaculites sp., Ammodiscus cretaceus, Gaudryina sp., Textulariopsis bettenstaedti that gradually disappear close to the top of OAE 2. Moreover, at ~1 m above the onset of the OAE 2, and simultaneously to the Plenus Cold Event (PCE), a repopulation event and ventilation at the seafloor is documented by the occurrence of the oxic benthic foraminiferal taxa Frondicularia sp. and Ramulina aculeata. Above the OAE 2 (lowermost Turonian), calcareous and agglutinated taxa re-occur with high species diversity and abundance, identifying moderately oxic conditions and mesotrophic regimes. In conclusion, oxygen and organic carbon variations at the seafloor associated to the OAE 2 can be inferred by the benthic foraminiferal composition and distribution.
Potential role of methane and other non-CO2 trace gases in past warm climates
Authors: Hopcroft Peter , Segalla Diane , Ramstein Gilles , Pugh Thomas
Published: February 2023

Past warm climates allow the evaluation model predictions of the response of the Earth System to elevated greenhouse gas levels. However, Earth System model simulations routinely underestimate high-latitude warmth for past states, meaning that the forcings provided to models, the models themselves or the climate reconstructions are in error. We focus on the first of these and review the potential role of varying levels of atmospheric trace gases besides carbon dioxide (non-CO2 trace gases), which has been investigated in relatively few studies to date. Using a combination of terrestrial biogeochemistry models and simplified atmospheric chemistry scheme we make first-order estimates of the radiative forcing by non-CO2 trace gases for the mid-Pliocene and compare these with new results for the Miocene. We will discuss the main uncertainties involved and review potential avenues for future research.
Wave turbulence in inertial electron magnetohydrodynamics
Authors: David Vincent , Galtier Sébastien
Published: February 2023

A wave turbulence theory is developed for inertial electron magnetohydrodynamics (IEMHD) in the presence of a relatively strong and uniform external magnetic field B0 = B0e∥. This regime is relevant for scales smaller than the electron inertial length de. We derive the kinetic equations that describe the three-wave interactions between inertial whistler or kinetic Alfvén waves. We show that for both invariants, energy and momentum, the transfer is anisotropic (axisymmetric) with a direct cascade mainly in the direction perpendicular (⊥) to B0. The exact stationary solutions (Kolmogorov–Zakharov spectra) are obtained for which we prove the locality. We also found the Kolmogorov constant CK ≃ 8.474. In the simplest case, the study reveals an energy spectrum in k⊥−5/2k∥−1/2 (with k the wavenumber) and a momentum spectrum enslaved to the energy dynamics in k⊥−3/2k∥−1/2. These solutions correspond to a magnetic energy spectrum ∼k⊥−9/2, which is steeper than the EMHD prediction made for scales larger than de.
Ray-theoretical and finite-frequency seismic traveltime predictions for tomographic filtering of 3D mantle circulation models
Authors: Freissler Roman , Schuberth Bernhard S.A. , Zaroli Christophe
Published: February 2023

Linking geodynamic models to observations from seismology is essential for improving our understanding of the present-day thermodynamic state of the mantle. From the geodynamic perspective, 3D mantle circulation models (MCMs) yield physically relevant predictions of the global distribution of buoyancy forces, while complementing information is available from seismic data and tomography that can reveal the location and morphology of mantle heterogeneity. Investigating this powerful interplay in a fully synthetic framework has great potential. It allows us to make robust interpretations of mantle structure provided that quantitatively meaningful comparisons can be made. This especially relates to the magnitudes of heterogeneity that can not be effectively constrained by the individual modelling approaches.Following this general concept, there are two possible links: 1) synthetic seismic data can be predicted from the MCM and statistically be compared against observed data. 2) the MCM gets modified by a tomographic operator (informing us about spatially variable seismic resolution and, if applicable, model uncertainty), and subsequently this filtered version gets compared against the corresponding tomographic image from real observations.Here, we discuss these two strategies together based on observed data for S-wave cross-correlation traveltime residuals that have been applied to global seismic tomography. Taking the same set of source-receiver configurations, synthetic traveltime predictions are computed in a state-of-the-art MCM using ray theory (RT), paraxial finite-frequency kernels (FFK), as well as cross-correlation measurements on synthetic seismograms (SPECFEM). The latter requires computationally demanding 3D-wavefield simulations using SPECFEM3D_GLOBE for an earthquake catalog comprising over 4,200 teleseismic events.These data sets can be used for tomographic filtering by application of the generalized inverse operator of the actual tomographic model. Filtered MCMs derived from the differently predicted data sets appear largely similar on a global scale with regards to the shape and amplitudes of imaged mantle heterogeneity. This is observed despite the lack of more accurate wave physics in RT or FFK and possible measurement errors for the SPECFEM data that, although being computed in a synthetic case, can not be completely ruled out. Stronger differences between filtered models appear in regions of higher image resolution where model uncertainty by propagated data errors can play a more prominent role.We discuss the impact of the different filtering strategies by comparing filtered models to the original MCM and synthetic traveltime residuals to the underlying real observations. The results strongly highlight the need for incorporating both resolution and model uncertainty in combined tomographic-geodynamic studies.