bluuebunny/crossref_metadata_2025 huggingface dataset:
A Hydrogenated amorphous silicon detector for Space Weather Applications
Authors: Grimani Catia , Sabbatini Federico ,   HASPIDE Collaboration
Published: March 2024

The fleet of present and future space missions aimed at studying the Sun and the solar-terrestrial relationships carryparticle detectors, among other instruments. The monitoring of intense solar activity and solar energetic particle (SEP)events provide fundamental contributions to Space Weather and Space Weather science. Unfortunately, very few of these instruments are optimizedfor the  measurement of the proton differential flux above 200 MeV/n. We show that by increasing this minimum energy to 400-600 MeV/n it is possible to infer the trend of the differential flux with small uncertainties up to GeV energies, while this is not the case if the measurements are limited  to 200 MeV/n. To this purpose, we report on the characteristics of a single instrument meant for the detection of  solar flares and high-energy particles, galactic magnetar activity and gamma-ray burst observations. The instrument is based on hydrogenated amorphous silicon as a sensitive material that presents an excellent radiation hardness and finds application for particle beam characterization and medical purposes.
 
Assessment of global high-resolution water storage simulations from the LISFLOOD hydrological model
Authors: Dobslaw Henryk , Jensen Laura , Dill Robert , Balidakis Kyriakos
Published: March 2024

Simulated terrestrial water storage (TWS) data from global hydrological models are indispensable for various geodetic applications, e.g., for simulating Earth orientation parameters, deriving time series of deformations of the Earth’s surface needed for the realization of global reference systems, or de-aliasing purposes of GRACE/-FO gravity products. So far, the Land Surface Discharge Model (LSDM) has been routinely used for such tasks at the GFZ. However, the current standard experiment of LSDM is already several years old, and many limitations are known, in particular a limited spatial resolution of 0.5°, which limits the accuracy of crustal deformation predictions close to rivers and lakes. In this contribution, we evaluate the suitability of LISFLOOD (https://ec-jrc.github.io/lisflood/), an open source, high-resolution hydrological rainfall-runoff-routing model, for geodetic purposes.We compare the performance of various global LISFLOOD model runs for the time period 2000 – 2022 against the current LSDM configuration. In addition to two LISFLOOD model generations, which differ in their spatial resolution (0.1° and 0.05°) and their input land surface parameter data set, we also explore a number of high-resolution (0.05°) model runs with respect to the influence of the soil depth on simulated TWS. Model results are validated against mass anomalies from the satellite gravimetry missions GRACE and GRACE-FO on different spatial and temporal scales. Furthermore, to demonstrate the benefit of the higher spatial resolution of LISFLOOD, we utilize data from selected ground based GNSS stations to validate the models’ performance regarding mass-induced loading.We find that LISFLOOD significantly outperforms LSDM in many regions, especially on interannual time scales, in terms of various validation metrics (i.e., correlation, root mean squared deviation, and explained variance). Analyzing the different LISFLOOD runs reveals advantages of the new (0.05°) over the old (0.1°) model version, and a large impact of the choice of soil depth on simulated TWS.
CDGP data center, new data for interdisciplinarity research 
Authors: Benlalam Salsabyl , Derode Benoit , Engels Fabien , Grunberg Marc , Schmittbuhl Jean
Published: March 2024

The Data Center for Deep Geotermal Energy (CDGP-Centre de Données de Géothermie Profonde, https://cdgp.u-strasbg.fr/) was launched in 2016 and managed by Interdisciplinary Thematic Institute for Geosciences for the energy system Transition (ITI GeoT, https://geot.unistra.fr/), with the purpose of archiving, preserving and distributing deep geothermal data in the Alsace region (France) for the scientific community and R&D activities. The CDGP is furthermore an internal node of EPOS TCS Anthropogenic Hazards (https://www.epos-eu.org/tcs/anthropogenic-hazards), the data provided concerning geothermal sites in Alsace are therefore also available on the EPISODES platform (https://episodesplatform.eu/), which enables users to process and analyze the data they download. The CDGP collects high-quality data from different phases of deep geothermal projects, especially from exploration and development phases. The aim of this service is to provide downloadable multi-disciplinary data, ranging from industrial hydraulic information to seismic records and catalogs, through geological logs and fault maps for example. The data are thoroughly filtered, controlled and validated by analysts, and are grouped into “episodes”, referring to a set of relevant geophysical data correlated over time, and establishing links between anthropogenic seismicity and an industrial activity.As part of the European Geo-INQUIRE project (GA n. 101058518, https://www.geo-inquire.eu/), we are now expanding the types of data that we distribute. The raw data (RINEX) from GNSS stations that are monitoring the surface deformation around geothermal site are now available on the website. In a next step, we will add complementary information and metadata to our provided database (e.g. precise position/velocity/strain) thanks to our collaboration with EPOS TCS GNSS. We are currently in the process of developing strategies with EPOS TCS GIM (Geological Information and Modeling)  to provide geological maps and borehole data for the “episodes” sites. The aim is to use the TCS GIM services currently under development and benefit of the synergy from the various leading projects.Specific procedures have also been implemented since the beginning of the project to respect international requirements for data management. FAIR recommendations, for example, are followed to distribute data that are Findable, Accessible, Interoperable, and Reusable. 
Direct observations of coupled ice-ocean interactions within a basal terrace beneath Thwaites Eastern Ice Shelf
Authors: Washam Peter , Schmidt Britney , Nicholls Keith , Davis Peter , Eayrs Clare , Hegelein Veronica , Lawrence Justin , Meister Matt , Quartini Enrica , Holland David , Bryson Frances
Published: March 2024

At present, considerable uncertainty surrounds the details of how Earth’s ice sheets interact with the surrounding ocean. This inhibits the reliability of future sea level rise projections from ice sheet models and highlights a need to better constrain ice-ocean interactions with in situ observations. Here, we present detailed ice and ocean data from beneath Thwaites Eastern Ice Shelf, Antarctica, collected with the underwater vehicle Icefin as part of the ITGC MELT project. The observations are a subset of the full data set that focus on the ice-ocean interactions within one 4-m-tall and 200-m-wide terrace formation in the ice base. We present ocean conditions in the terrace from 18 hydrographic profiles that reached within 1 cm of the ice along the feature’s flat roof and 13 cm from its steep sidewall. The ocean observations depict highly stable near-ice ocean stratification within 1 m of the terrace roof that break down near its sidewall, allowing warmer and more saline water to contact the ice there. The ocean observations are combined with ice base elevations and scaled morphological melt patterns in the ice to understand the dominant mechanisms driving ice-ocean interactions within this feature. We then input these data into the three-equation melt parameterization to estimate spatial variability in melt rates within these topographic features. We test various parameterizations for ocean heat flux into the flat and sloped ice surfaces, and compare the results to melt rates sampled along a nearby terrace sidewall and roof with a phase sensitive radar. This work in progress aims to better understand how ocean conditions interact with ice slope on small scales to drive variable melting in warm, highly stratified environments, with hopes of refining existing parameterizations of this process. We expect regions beneath much of the ice shelves occupying West Antarctica to interact similarly with the underlying ocean to what we observe beneath Thwaites. Hence, our observations hold relevance for how ice sheet models parameterize ocean-driven melting in this type of melt-driven regime.
Development of a dusty cirrus calendar based on satellite data
Authors: Moradikian Samaneh , Moghim Sanaz , Hoshyaripour Gholam Ali
Published: March 2024

Mineral dust particles have the potential to serve as natural nuclei for cirrus cloud formation in the upper troposphere. Several studies demonstrate that dust aerosol plays a pivotal role in initiating cirrus clouds and forming extended optically thick cirrocumulus decks known as “dusty cirrus”. Despite this, our ability to accurately identify and predict these climatically significant clouds is still limited. In this work, we propose an algorithm to identify dusty cirrus clouds based on satellite data over the Aral Sea region between 2006 and 2021. The algorithm uses the CALIOP Vertical Feature Mask (VFM) to verify the coexistence of dust particles and cirrus clouds and determine the occurrence of dusty-cirrus. To enhance the accuracy of the algorithm, temperature obtained from an external source (the GEOS-5 data product supplied to CALIPSO) is also incorporated as a constraint for cirrus cloud identification. A random selection of identified dusty cirrus events (5% of the data, 90 events) is cross-validated against other data sources including cloud top temperature (MODIS), cloud top height (MODIS), and AOD (MODIS and VIIRS). The cross-validation confirms approximately 97% of the events to be associated with dusty-cirrus. This confirms that the developed algorithm can be used for developing a dusty cirrus calendar using available CALIOP data. This calendar reveals different facts about the dusty-cirrus occurrence in the study area. Out of the 4407 available samples, 2709 cirrus cloud events are identified, with approximately 65% (1790 events) of them being associated with dusty cirrus. The average values obtained for summer, fall, winter, and spring are 54%, 63%, 66% and 75%, respectively. Annual and seasonal trend analysis reveals different increasing rates for this region. Despite the important uncertainties, our analysis and results suggest that the proposed algorithm can be used for first-order identification and statistical analysis of dusty cirrus.
Electron to Light Ion Density Ratios During Cassini’s Grand Finale: Addressing Open Questions About Saturn’s Low-latitude Ionosphere
Authors: Dreyer Joshua , Vigren Erik , Johansson Fredrik L. , Hadid Lina , Morooka Michiko , Wahlund Jan-Erik , Waite J. Hunter
Published: March 2024

During Cassini's Grand Finale in 2017, the number densities of electron and light ions in Saturn's low-latitude ionosphere were measured in situ. This region is strongly influenced by the influx of ring material from Saturn's D ring.The electron data from the onboard Langmuir probe (LP) and light ion densities from the Ion and Neutral Mass Spectrometer (INMS) correlate very well even on short timescales after correcting the INMS timestamps, whereas prior the correlation was limited to broader scales. We analyze the electron-to-ion ratios for the proximal orbits and identify three distinct regions in Saturn's ionosphere:1) For altitudes above ∼2500 km and latitudes between -20° and 20°, the electron-to-light-ion ratios for the four analysed orbits are generally 8000 km) the ratios increase rapidly. This may indicate the presence of heavier ions, such as O+ and water group species, spiralling in from the C ring.
Seasonal quantification of the inter-city transport of PM2.5 in the Yangtze River Delta region of China based on a source-oriented chemical transport model and the Michaelis-Menten equation
Authors: Hu Jianlin , Gong Kangjia , Xie Xiaodong
Published: March 2024

Regional transport plays a crucial role in the pollution of fine particulate matter (PM2.5) over the Yangtze River Delta region (YRD). A practical joint regional emission control strategy requires quantitative assessment of the contribution of regional transport. In this study, the contribution of inter-city transport to PM2.5 among the 41 cities in the YRD region were quantitatively estimated using a source-oriented chemical transport model, and then the relationship between the cumulative contribution of regional transport and the distance was examined using the Michaelis-Menten equation. The results show that the Michaelis-Menten equation is suitable to represent the relationship between the cumulative contribution and transport distance. The coefficient of determination (r2) of the fittings is greater than 0.9 in 71% of the cases in the six subregions and four seasons in YRD. Two key parameters in the Michaelis-Menten equation K1, indicating the maximum contribution of regional transport, and K2, indicating the distance to which the regional transport contribution reach half the maximum contribution, show substantial regional and seasonal variations. The average K1 is 73.6%, with lower values observed in the northern part of the YRD and higher values in central Jiangsu. K2 is larger in northern Jiangsu, as well as central and southern Zhejiang. The local contribution in autumn and winter is lower than that in spring and summer in the northern part of the YRD. Particularly in northern Jiangsu, the local contribution reaches 90.4% in summer but drops to 53.0% in autumn and winter, illustrating significant impacts of regional transport to PM2.5 in autumn and winter in this area. K2 is larger on polluted days, compared to clean days, indicating greater contributions from regional transport to PM2.5 in YRD. The results can serve as a scientific foundation for implementing regional joint prevention and control measures in the YRD region.
Impact of radiation, water vapour and ice clouds on the tropopause region
Authors: Spichtinger Peter , Reutter Philipp
Published: March 2024

In the tropopause region, the thermal structure is strongly influenced by the interaction of radiation, ice clouds and water vapour. Features as the tropopause inversion layer as well as potentially unstable layers are suspected to be (partly) driven by radiative effects in connection with the frequently occurring large concentrations of water vapour (i.e. supersaturations with respect to ice) and ice clouds. Since there is a high variability of water vapour and ice clouds in terms of microphysical properties and vertical layers, it is still unclear under which conditions clouds and their precursor (i.e. water vapour) lead to a stronger or a weaker stratification, respectively.In this study we investigate the interaction of radiation and clouds within an idealized framework of a combined cloud-radiation scheme within a vertical column. Using different environmental conditions in terms of water vapour concentrations, ice cloud properties, and thermal stratification we investigate the temporal evolution of the thermodynamic properties of the tropopause region. The results are statistically investigated for characterizing dominant impacts and feedbacks.
Uncertainty spreading and shrinking among eight land carbon cycle models in response to climate change
Authors: Luo Yiqi
Published: March 2024

Large uncertainty in model predictions of land carbon responses to climate change has been ubiquitously demonstrated in model intercomparison projects (MIPs). The large uncertainty become a major impediment in advancing climate change prediction. Thus, it is imperative to identify sources of the uncertainty before we can fully understand and address the uncertainty issue. In this presentation, I show a novel matrix approach to analytically pin down the sources of model uncertainty in predicting carbon dynamics in response to rising atmospheric CO2 concentration and increasing temperature. We developed a matrix-based MIP by converting the carbon cycle module of eight land models (i.e., TEM, CENTURY4, DALEC2, TECO, FBDC, CASA, CLM5 and ORCHIDEE) into eight matrix models. In response to rising atmospheric CO2 concentration and increasing temperature, predicted ecosystem net primary production (NPP), net ecosystem production (NEP), and net ecosystem carbon storage spread among the eight models as simulations go over time. We applied the traceability analysis method to decompose simulated carbon dynamics to their traceable components according to the matrix equations. Our analysis indicates that the uncertainty among the eight models was mainly due to inter-model difference in baseline carbon residence time and environmental scalar. Once the sources of model uncertainty were identified, we sequentially standardized model parameters to shrink simulated ecosystem carbon storage and NEP to almost none. Our study demonstrates that the sources of uncertainty in carbon cycle modeling can be precisely traced to model structures and parameters, regardless of their complexity, so that the uncertainty issue for MIPs can be precisely understood and well addressed.
Will 2024 be the first year above 1.5 C?
Authors: Dunstone Nick , Smith Doug , Scaife Adam , Hermanson Leon , Colman Andrew , Folland Chris
Published: March 2024

Global mean surface temperature is the key metric by which our warming climate is monitored and for which international climate policy is set. At the end of each year the Met Office makes a global mean temperature forecast for the coming year. Following on from the new record 2023, we predict a high probability of another record year in 2024 and a 35% chance of exceeding 1.5 C above pre-industrial. Whilst a one-year temporary exceedance of 1.5 C would not constitute a breech of the Paris Agreement target, our forecast highlights how close we are now to breeching this target. We show that our 2024 forecast can be largely explained by the combination of the continuing warming trend of +0.2 C/decade and the lagged warming affect of a strong tropical Pacific El Nino event. We further highlight 2023 was significantly warmer than forecast and that much of this warming signal came from the southern hemisphere and requires further understanding.
Estimation of the dynamical contribution to European temperature variations.
Authors: Cariou Enora , Cattiaux Julien , Qasmi Saïd , Ribes Aurélien
Published: March 2024

Europe is one of the fastest-warming region of the world and temperatures of the recent years have been systematically higher than best estimates of the forced response. This may be due to internal variability in favor of warmer situations, or it may indicate that the forced response is underestimated.In Europe, inter-annual temperature variations are primarily linked to the variability of North Atlantic atmospheric dynamics. The temperature T for a given day and year can be written as the sum of the forced response µ (the non-stationary climate normal) and the internal variability D + ε (D the atmospheric dynamics and ε the residual).We investigate two methods for estimating the forced response in transient simulations, via a denoising of the temperature T from the dynamical term D. To test these methods, we use a perfect model framework, here the large ensemble of 50 MIROC6 transient simulations. The mean of the large ensemble provides an accurate estimate of the forced response (the « truth »), to which estimates from individual members can be compared.The contribution of the D term is first estimated with a circulation analogues method. We reconstruct the temperatures of one individual member from similar atmospheric situations of the other 49 members. The analogues are calculated on the T-µ series, rather than on the T series directly.Second, we reconstruct temperatures using deep neural networks. Using a U-NET, we estimate the function f in the equation T=µ+f(X)+ ε, where X is the sea level pressure. Our network is trained on the different members of the large ensemble.
A mechanism for reconciling the synchronisation of Heinrich events and Dansgaard-Oeschger cycles
Authors: Schannwell Clemens , Mikolajewicz Uwe , Kapsch Marie-Luise , Ziemen Florian
Published: March 2024

The evolution of the northern hemispheric climate during the last glacial period was shaped by two prominent signals of glacial climate variability known as Dansgaard-Oeschger cycles and Heinrich events. Dansgaard- Oeschger cycles are characterised by a period of rapid, decadal warming of up to 14°C in the high northern latitudes, followed by a more gradual cooling spanning several centuries. Temperature reconstructions from ice cores indicate a dominant recurrence interval of ∼1,500 years for Dansgaard-Oeschger cycles. Heinrich events are quasi-episodic iceberg discharge events from the Laurentide ice sheet into the North Atlantic. The paleo record places most Heinrich events into the cold phase of the millennial-scale Dansgaard-Oeschger cycles. However, not every Dansgaard-Oeschger cycle is accompanied by a Heinrich event, revealing a complex interplay between the two prominent modes of glacial variability that remains poorly understood to this day. Here, we present simulations with a coupled ice sheet-solid earth model to introduce a new mechanism that explains the synchronicity between Heinrich events and the cooling phase of the Dansgaard-Oeschger cycles. Unlike earlier studies, our proposed mechanism does not require a trigger mechanism during the cooling phase. Instead, the atmospheric warming signal associated with the interstadial phase of the Dansgaard-Oeschger cycle causes enhanced ice stream thickening such that a critical ice thickenss and temperature threshold is reached faster, triggering the Heinrich event during the early cooling phase of the Dansgaard-Oeschger cycle. An advantage of our mechanism in comparison to previous theories is that it is not restricted to marine-terminating ice streams, but applies equally to land-terminating ice streams that only become marine-terminating during the actual Heinrich event. Our simulations demonstrate that this mechanism is able to reproduce the Heinrich event characteristics as known from the paleo record under a wide range of forcing scenarios and provides a simple explanation for the observational evidence of synchronous Heinrich events from different ice streams within the Laurentide ice sheet.
Hydrological modelling of the extreme flooding event of July 202
Authors: Baguis Pierre , Van den Bergh Joris , Roulin Emmanuel , Gellens-Meulenberghs Françoise
Published: March 2024

The flooding event of July 2021 is a natural disaster that resulted in fatalities and extensive damage to infrastructure. The flood was triggered by the extreme precipitation event of 13-16 July 2021. We investigate it for a selection of catchments of the Meuse River in Belgium using hydrological modelling and forecasting. We make use of a high resolution radar-based quantitative precipitation estimation of the event (RADFLOOD21), generated at the Royal Meteorological Institute of Belgium. This dataset is used to perform simulations with the hydrological model SCHEME in order to analyze the hydrometeorological conditions responsible for the flooding. Hydrological reforecasts are also performed, using the RADFLOOD21 data for initialization and precipitation hindcasts as input to a hydrological prediction system. Precipitation hindcasts are provided by numerical weather prediction (NWP) models, including the ECMWF ENS ensemble predictions. The main goal of the study is to evaluate the model and forecasting system performance in terms of river discharge for this exceptional precipitation event, and to investigate the impact of the new input data.
Peatland GHG emissions estimated with redox potential
Authors: Boonman Jim , Harpenslager Sarah Faye , Tolunay Duygu , Buzacott Alexander , van den Berg Merit , van Dijk Gijs , Smolders Alfons , Hefting Mariet , van der Velde Ype
Published: March 2024

Peat decomposition processes account for ~2% of the annual anthropogenic greenhouse gas emissions (GHG). The rate of microbial peat respiration is determined by temperature, the quality and abundancy of organic matter, moisture and electron acceptor (such as O2, Fe[III], SO42-) availability. The redox potential and pH reflect the chemical state of the soil and are an indicator for biogeochemical metabolic processes that occur within the soil. Here, we introduce a novel methodology to estimate peatland GHG emission (CO2 and CH4) by linking soil temperature and redox potential over time and depth with aerobic and anaerobic CO2 and CH4 incubation fluxes. Soil metabolic processes (at 0.1, 0.3, 0.5, 0.7 and 0.9 m depth) were classified based on the redox potential and pH. Individual rates of CO2 and CH4 emission (based on newly acquired and literature lab incubation data) were assigned to aerobic, anaerobic and methanogenic metabolic processes and were multiplied by a soil temperature factor relying on a Q10 relation. The estimated GHG emissions were compared with measured eddy covariance and automated transparent chamber GHG fluxes, both on short and long timescales for various agriculturally managed or semi-natural minerotrophic peatlands in the Netherlands. Our results indicate that seasonal patterns in GHG emissions are well captured by our approach. Moreover, estimations of short term (< 1 week) GHG dynamics matched measured GHG fluxes well for research locations with high methane emission. During our presentation we elaborate upon new results and discuss the suitability to indirectly determine peatland GHG emissions by measuring the soil redox potential.
UAV-based imagery for monitoring and predicting vegetation water stress across landscape-scale gradients
Authors: El-Mejjaouy Yousra , Hufkens Koen , Walthert Lorenz , Schoch Julian , Stocker Benjamin
Published: March 2024

The extreme summer droughts across Central Europe (i.e., 2003, 2015, and 2018), driven by anthropogenic climate change, emphasized the urgency of understanding and predicting ecosystem responses to extreme droughts.Water limitation during severe drought limits photosynthesis and respiration by closing stomata, induces xylem cavitation, and reduces plant carbon balance, which leads to seasonal decreases in productivity and long-term increases in tree vulnerability to major disturbances and mortality. Drought-induced stress can be measured by remote sensing as it influences physical leaf properties and alters leaf spectral responses in both the visible and thermal part of the spectrum.The physiological responses to drought events not only depend on their timing, i.e. recurrence and duration, but also on their geography (landscape-scale heterogeneity). For example, large gradients in soil depth, slope, and exposition in mountainous landscapes can therefore cause differential vegetation responses to drought across scales of 101-104 m. Combining both vegetation (spectral) indices, and a highly variable geography, offers a non-destructive and rapid method for investigating plant physiological processes under a wide range of drought stress.Our research maps temporal variations and landscape-scale heterogeneity in vegetation water stress using UAV-based multispectral remote sensing. To investigate landscape-scale heterogeneity of drought impacts, the study is carried out at various sites in Valais, Switzerland, with different elevations, soil and plant rooting depths, slopes, and various species exhibiting varying responses to drought stress. All sites are part of a larger tree monitoring network and provide co-located plant and soil-point measurements of water stress. Here we outline the heterogeneity in the study locations, the methodological approach, as well as tree responses during recent summers at these sites. The collected data will be used to develop predictive models for water stress using UAV imagery, aiming to upscale the effects of water stress on vegetation functioning across a heterogeneous landscape. 
Variations in regional hydrological environment and human activities inferred from δ18O and δ2H of stalagmite fluid inclusions in southwest China
Authors: Wu Yao , Warken Sophie , Li Jun-Yun , Li Ting-Yong , Frank Norbert
Published: March 2024

The interpretation of δ18Oc and δ13Cc values of stalagmites within China is still complex, although numerous cave archives have been reported in this region. Present challenges include distinguishing between natural and anthropogenic influences on regional hydrological and environmental changes, in particular due to the increasing human activities during the mid-to late Holocene. Here, we report for the first time the δ18Ofi and δ2Hfi records of fluids entombed as inclusions during the Holocene (6290 to 690 yr BP) from a stalagmite from southwest China. We excluded measurement-induced artefacts using Rayleigh fractionation models and improved measurement methods, producing reliable results. We observed very high δ18Ofi and δ2Hfi values during a weak Asian summer monsoon (ASM). Our record reveals six drought events during the mid- and late-Holocene (~950, 1360, 2260, 3450, and 5600 yr BP), which coincide with the weakening of ASM intensity and variations in low latitude forcing, such as tropical sea surface temperature, El Niño/Southern Oscillation, and intertropical convergence zone. In 950-1100 A.D., the dramatic enrichment of δ18Ofi (magnitude ~7‰) corresponds with the increase in regional population density due to large-scale population migration at this time (historically known as the Jingkang event). The overall coefficient of variation (C.V = standard deviation/mean) of the δ18Ofi sequence is 125% compared to only 5% for δ18Oc. Hence, δ18Ofi seems to exhibit a greater sensitivity to regional environment wet/dry variations than traditional carbonate isotope proxies.
On the time and space scales of geological, climatic, and biological changes
Authors: Husson Laurent , Lorcery Manon , Salles Tristan
Published: March 2024

It is commonplace to claim that the geo-, atmo-, and bio- spheres of the Earth are coupled, or that biodiversity depends on their interplays, but the implicit hypothesis on the time and space scales at which coupling holds are seldom envisioned. For instance, "deep time" is a convenient shortcut that loosely conveys the ideas of steady state and large spatial scales, but what are the limits? Observations often fall short because the geological record is fragmentary, but also because it is uncommon to access crucial informations such as rates of speciation, extinction, or migration. Recent advances in numerical landscape evolution models permit to explore the dynamic equilibrium between the spheres of the Earth. Based on a few examples at different time and space scales, we will browse settings where steady state holds (where biodiversity depends on the instantaneous states of the geology and climate, as for instance set by the Wilson cycle), where transient state prevails (where considering the time derivative of their states is needed, as for instance when the pace of landscape reshaping promotes biodiversification), and where dynamic equilibrium breaks down in some sort of metastable situations (as in the press-pulse theory that well applies to the mass extinction events). 
Direct Measurements of Field-Particle Energy Exchange and Anomalous Effects Associated with Electromagnetic Turbulence in Electron Diffusion Region of Collisionless Magnetic Reconnection
Authors: Zhong Zhihong , Zhou Meng , Graham Daniel , Khotyaintsev Yuri , Pang Ye , Tang Rongxin , Deng Xiaohua
Published: March 2024

Magnetic reconnection and turbulence are two fundamental cross-scale processes in collisionless plasmas. Whether kinetic-scale electromagnetic (EM) turbulence can drive and support fast collisionless reconnection is an open and controversial question. In this work, we directly estimated the net field-particle energy exchange and anomalous electric fields associated with EM turbulence within the electron diffusion region, where the magnetic field lines were broken and reconnected. The results confirmed that these anomalous electric fields are mainly contributed by anomalous viscosity term. The maximum contribution of anomalous effects can be up to about 20% of the fast reconnection electric field, while that in most events is less than 5%. Furthermore, the locally generated EM turbulence is inclined to support the fast reconnection, while the locally damping EM turbulence could backfire on the fast reconnection.
Josephine Submarine Seamount: New Insights from multibeam data and seabed sampling for environmental conditions in the Early Quaternary
Authors: Carvalho Vasco , Terrinha Pedro , Neres Marta , Voelker Antje , Batista Luís , Rosa Marcos
Published: March 2024

The Josephine submarine seamount is located in the NE Atlantic Ocean around 470 km west of the coast of mainland Portugal and 500 km northeast of Madeira Island on the vicinity of the Africa-Eurasia plate boundary. With 47 km in length and 10 km in width, it rises 2500 meters above the adjacent abyssal plains, with its top standing at a depth of 170 m. It is a basaltic submarine seamount that yielded ages of 16.3 ± 0.9Ma to 11.7±0.7Ma (Geldmacher et al. 2006).Multibeam and backscatter data were acquired to increase our knowledge about the seamount. The backscatter data shows the presence of fine sediment on the eroded top of the seamount, not present in the northern part. The top of the seamount dips gently (~1º) to the northwest allowing the deposition of fine grained sediment down to ~500 m where the seafloor is irregular with slopes dipping between 10⁰ and 15⁰ and the igneous rocks crop out.Morphologic analysis suggests that the very flat and smooth surface of the southernmost portion of Josephine Seamount has been above sea level and subjected to near coastal erosive processes of areas lying at ~420 m depth. Since the sea level of the last 15 Ma has not been lower than 160 m of the present-day levels (Miller et al. 2020), tectonic and/or erosional processes must have lowered the seamount’s height by at least 260 meters.Sedimentary rocks were dredged from depths from 480 to 347 m, on the southeastern part of the Josephine seamount and were analyzed for their shape, composition and sedimentary facies. The dredged samples are calciclastic limestone blocks that have a half horn torus shape (donut). Most of the specimens are trespassed by a 3 to 5 cm long conical cavity that developed from the base to the top of each sample.The rocks consist of 96.6% of foraminifera tests (82.4% planktic and 17.6% benthic), with a very low mineral content. The grains are diagenetically cemented by a calcite matrix (confirmed by EDS analysis). The presence of the planktonic foraminifera species Globorotalia truncatulinoides, whose first occurrence dates of 1.93 Ma (Wade et al., 2011), provides a maximum age of formation, making these sedimentary rocks at least 10 Ma younger than the volcanic rocks that constitute the Josephine Seamount basement. The presence of the benthic foraminifera Lobatula lobatula and Discanomalina semipunctata indicate strong currents that could have contributed to the erosion of the seamount’s top.This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds through the project LISA (https://doi.org/10.54499/PTDC/CTA-GEF/1666/2020).
Enhancing Geoscience Analysis: AI-Driven Imputation of Missing Data in Well Logging Using Generative Models
Authors: Al-Fakih Abdulrahman , Koeshidayatullah Ardiansyah , Kaka Sanlinn
Published: March 2024

The integrity of well logging data is paramount in geophysical explorations for accurate subsurface analysis, notably in the North Sea Dutch region known for its extensive hydrocarbon exploration. Addressing the common challenge of missing data in well logs, our study introduces an AI-driven methodology employing generative models. These models utilize machine learning to analyze existing data patterns and generate realistic imputations for missing values. The approach has shown to not only enhance the quality of geological interpretations but also to streamline the workflow in hydrocarbon exploration. This integration of AI signifies a substantial move towards more precise and efficient geoscience data analysis. A qualitative comparison using Principal Component Analysis (PCA) and t-Distributed Stochastic Neighbor Embedding (t-SNE) was conducted to evaluate the results. The PCA comparison demonstrates the synthetic data’s alignment with real data in principal component space, effectively capturing the variance. The t-SNE analysis further validates the model's fidelity, with the synthetic data exhibiting clustering behaviors analogous to real data. Together, these results showcase the transformative potential of machine learning in geosciences, providing a robust framework for enhancing data reliability in geophysical studies.
Effects of timber harvesting techniques on soil biodiversity and greenhouse gas fluxes of temperate forest soils susceptible to compaction
Authors: Hofbauer Armin , Behringer Maximilian , Froemel Marcus , Gasser Lisa , Grünberg Julian , Haas Christoph , Katzensteiner Klaus , Kühmaier Martin , Markart Gerhard , Meissl Gertraud , Nemestothy Nikolaus , Rewald Boris , Scheidl Christian , Schlögl Matthias , Wieshaider Alexandra , Kitzler Barbara
Published: March 2024

Temperate forests are a substantial sink for the greenhouse gases (GHG) methane (CH4), carbon dioxide (CO2) and soil emissions of nitrous oxide (N2O) are low. However, most of these forests are managed with ground-based harvesting systems causing severe soil disturbance. Soil displacement and compaction has a long-term effect on the soil microbial community structure and alters soil respiration, CH4 uptake, and nitrogen turnover. This significantly reduces the soil ecosystem services on extraction tracks and landings. Soil disturbance is particularly severe and persistent in compaction-prone silty and loamy soils, emphasizing the urgent need for specific techniques for these sites.In an empirical Before-After Control-Impact study we compare the effects of harvester-forwarder use with/without tracks (HF/HFt) and cable-yarding with motor-manual-felling (CMM), on the soil chemistry, microbial community, and the soil-GHG balance. Our study is carried out within the project HoBo: Securing the Sustainability of Forest Soil Functions via Optimized Harvesting Technologies (https://dafne.at/projekte/hobo). The study sites are located in the Flysch zone and in the Molasse basin (North Alpine foreland basin). Soil GHG flux rates of CO2, CH4, and N2O are measured with trace gas analyzers (Li-Cor 7810 and 7820), either manually at the recently thinned stands, or continuously with automatic chambers at plots that were thinned in 2016.  For deeper understanding of the effects on soil chemistry and the changes in the microbial community, we determine nitrogen availability, microbial biomass carbon and nitrogen as well as the phospholipid fatty acids (PLFA).Preliminary results show a significant impact of all applied mechanized timber harvesting systems (HF/HFt/CMM) reducing CH4 uptake rates and increasing N2O emissions of both skid trails and cable yarding corridors, compared to the control plots outside the extraction tracks (thinned stand). Our findings underline that sustainable forest management practices should not only reduce soil compaction. It should also consider additional factors, particularly soil displacement induced by logging activities.
HoStIr: Holocene Storminess in Ireland
Authors: Pyne-O'Donnell Sean , Shaw Helen , Turner Jonathan , Carter Elliot , Stock Michael , Mitchell Fraser , Curran Michelle , Swindles Graeme , Evans Callum , Orme Lisa
Published: March 2024

HoStIr is a palaeoclimate research project investigating how and why storminess has changed throughout the Holocene in Ireland. The project has three stages: 1) testing of proxies for storminess, 2) development of three Holocene storm reconstructions for Ireland, and 3) a data-model comparison of past storminess.
Here, we present the preliminary results of the first stage of the project, where we are testing two potential indicators of past sea spray deposition in coastal peatlands. Past storminess has primarily been investigated using sand-based proxies deposited by wind or waves into coastal depositional environments. By testing proxies related to the deposition of sea spray during storms, it is anticipated that storminess reconstructions can be developed from a wider range of sites.
The first potential proxy is preserved bromine within peat, which potentially reflects the deposition and retention of sea salt. The second is the biomass of microscopic testate amoebae preserved in peat, as a previous study from the sub-Antarctic suggests this can be influenced by changing salinity as a result of sea spray (Whittle et al. 2019). Thirty cores have been sampled along a transect from a coastal peatland on the west coast of Ireland, spanning a gradient of marine influence. We will present preliminary results of the bromine retention along this transect, measured using XRF analysis and with tephrochronology used for age control, as well as the results of the testate amoebae biomass. Bromine concentrations along two cores has also been assessed by ITRAX (X-Ray Fluorescence) core scanning and compared with humification analysis, to test the possibility that bromine concentrations are influenced by the degree of peat humification.
Analyses of this and the remaining project stages is ongoing. It is anticipated that this first stage, if successful, will provide a methodological breakthrough by proving that peatland sea-spray proxies provide reliable evidence for past storminess and would enable storminess records to be developed more extensively than sand-based approaches alone.
 
Whittle, A. et al. (2019) ‘Salt-Enrichment Impact on Biomass Production in a Natural Population of Peatland Dwelling Arcellinida and Euglyphida (Testate Amoebae)’, Microbial Ecology, 78, pp. 534–538.
Study of Dust Impact Signals around Mars using MAVEN/LPW Observations
Authors: Ijaz Samia , Vaverka Jakub , Němeček Zdeněk , Šafránková Jana
Published: March 2024

Electric field instruments can detect dust impacts on a spacecraft body as transient pulses in the measured electric field. Our study investigates these transient (millisecond) pulses detected by the Langmuir Probe and Waves (LPW) instrument onboard the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. We present a statistical analysis of 360,000 medium frequency burst electric field waveforms recorded in 2015; the study aims to identify and analyze the characteristics of these transient pulses. An automatic routine is used to detect waveforms with rapid fluctuations in the electric field data; this comprises over 12,000 events in the dipole and nearly 5,000 in the monopole configurations. Our findings reveal that most of the pulses in monopole configuration are likely the result of interference rather than dust impacts. Our analysis mainly focuses on dipole observations, which predominantly consist of bipolar events typically associated with dust impacts. These events are mainly detected in the Martian ionosphere, where the spacecraft is negatively charged. Fewer events are recorded when the spacecraft is positively charged, with a maximum at an altitude of 1200 km. The low detection rate of dust impact signals outside the ionosphere suggests that the planet is the most probable source of these dust particles. However, the physical processes by which dust grains are lifted from the surface of the planet to high altitudes are not clear, and thus a possibility that the signals observed might not be generated by dust impacts remains for further investigations.
Combining convection permitting modeling results with CMIP6 global climate model results to produce scenarios for local precipitation extremes
Authors: Lenderink Geert , de Vries Hylke , van Meijgaard Erik
Published: March 2024

Convection permitting climate models (CPMs) display much improved present-day rainfall statistics at local scales as compared to common regional and global climate models. Yet, because CPMs are computationally very demanding, runs are short — typically covering 10 to 20 years  only  —  which makes it hard to distinguish the changes due to global warming from the noise due to internal variability. In addition, runs cover a limited set of changes at larger scales as only few global climate models have been downscaled so far. This challenges the representativeness of the results. Here, we discus these issues within the context of the production of the Dutch climate scenarios issued in fall 2023. We use spatial pooling of information to improve signal to noise. To produce scenarios for local rainfall extremes, we combined information from the CPMs with information from CMIP6 and one RCM (RACMO) using a simple scaling framework. From the CPMs we derived sensitivities of changes in rainfall intensity to surface dew point temperature change. By using spatial pooling and by taking out rain frequency change (using wet conditional statistics) a reasonable collapse of the data of 7 CPM simulations could be obtained, with typical dependencies between 1 and 2 times the Clausius Clapeyron relation. The change in rain frequency and the dew point temperature are derived from a  set of RACMO simulations using pseudo-global warming perturbations derived from CMIP6 combined with a simple perturbed physics method. With these RACMO simulations we covered a range in large-scale conditions compatible with CMIP6.  Subsequently, rain intensity change and frequency change are combined using a transformation of the observed rainfall distribution.  In this way, we could produce a set of climate scenarios for daily and hourly precipitation extremes covering a wide range in global change conditions. Besides these changing rainfall statistics, we also analyzed the spatial temporal characteristics of showers in order to investigate whether showers become larger in scale in the future climate.
Balancing simplicity with efficiency: a comparison of river flood mapping models on past events on the French Mediterranean coast
Authors: Royer-Gaspard Paul , Troin Magali , Fox Dennis
Published: March 2024

Floods are one of the most dangerous and disastrous natural hazards that cause economic damages and human loss. In particular, flash floods related to heavy precipitation represent a major hazard on the French Eastern Mediterranean coast where growing population and tourism increase the exposure and vulnerability of coastal cities to extreme events. A few well recorded severe events have demonstrated the vulnerability of this area to river floods during the last 15 years. Consequently, various modelling approaches has been recently proposed to support flood prevention and mitigation in urban region. However, mapping floods events with limited computational costs remains challenging. In this study, four open-source numerical flood mapping tools are compared regarding their ability at simulating past flood events over five catchments in the southeastern region of France. The flood mapping models range from the simple Height Above Nearest Drainage approach (MHYST) to more complex methods that solve the full shallow water equations (LISFLOOD-FP DG2). Models of intermediate complexity, such as a 1D shallow water solver (HEC-RAS) and a 2D cellular automata (CAflood), are also included. Model evaluations are performed based on water depth accuracy estimation against high water marks data. The flood mapping tools are also compared in terms of flood extent using critical success indices. This study outlines how the more complex models provide the more accurate and realistic flood simulations, however with high computationally demanding which requires the deployment of substantial computer resources before their use in operational flood systems.