bluuebunny/crossref_metadata_2025 huggingface dataset:
AI-driven spatiotemporal quantification and prediction of soil salinity at European scale using the LUCAS database
Authors: Zarif Mohammad Aziz , Hassani Amirhossein , Panagos Panos , Lebron Inma , Robinson David A. , Shokri Nima
Published: March 2024

Soil salinization, referring to the excessive accumulation of soluble salt in soils, adversely influences nutrient cycling, microbial activity, biodiversity, plant growth and crop production thus affecting soil health and ecosystem functioning. Soil salinity quantification is a major step toward mitigation of its effects. Therefore, developing quantitative tools to predict soil salinity at regional and continental levels under different boundary conditions and scenarios is crucial for sustainable soil management and security of natural resources (1-3). This study proposes an AI-driven soil salinity quantification and projection approach focused on EU soils using a set of environmental covariates which consist of soil properties, terrain attributes, climate, and remotely sensed variables. The soil salinity point data which was used for model training and validation, expressed as electrical conductivity, was obtained from the LUCAS survey for the years 2015 and 2018. The novelty of this work lies in the careful integration of LUCAS data point with AI-driven models aiming to produce soil salinity maps for EU soils. Different AI algorithms including Random Forest, LightGBM, and XGBoost were used in this study enabling us to evaluate the performance of each algorithm in predicting soil salinity across EU with the XGBoost algorithm producing the most accurate results. Feature engineering technique was applied to reduce the models’ collinearity; thus 17 covariates were selected as the most important model variables influencing soil salinity from the initial 34 covariates investigated in our analysis. The output of the predictive model will be a gridded dataset illustrating the spatial and temporal (yearly) distribution of soil salinity across the EU, accompanied by the corresponding uncertainty maps with the spatial resolution of 1-km. This information is crucial for identifying regions with elevated salinity levels and formulating necessary action plans to mitigate the situation.ReferencesHassani, A., Azapagic, A., Shokri, N. (2020). Predicting Long-term Dynamics of Soil Salinity and Sodicity on a Global Scale, Proc. Nat. Acad. Sci., 117(52), 33017-33027, https://doi.org/10.1073/pnas.2013771117
Hassani, A., Azapagic, A., Shokri, N. (2021). Global Predictions of Primary Soil Salinization Under Changing Climate in the 21st Century, Nat. Commun., 12, 6663. https://doi.org/10.1038/s41467-021-26907-3
Shokri-Kuehni, S.M.S., Raaijmakers, B., Kurz, T., Or, D., Helmig, R., Shokri, N. (2020). Water Table Depth and Soil Salinization: From Pore-Scale Processes to Field-Scale Responses. Water Resour. Res., 56, e2019WR026707, https://doi.org/10.1029/2019WR026707
Alternative tree-cover states of dryland ecosystems: Inconsistencies between global and continental scales
Authors: Ma Li , Yang Liping , Chang Qinqin , Wang Siqing , Guan Chao , Chen Ning , Zhao Changming
Published: March 2024

Dryland ecosystems are complex systems that can exhibit alternative tree-cover states, making conservation and restoration efforts challenging. However, our understanding of these states is still limited, particularly at the global level. In this study, we utilized remote sensing data to analyze the distribution of tree cover in drylands and assess the impacts of factors such as the aridity index, temperature, fire frequency, and grazing on tree cover at both the global and continental scales. The results showed that dryland ecosystems in Asia, Australia, and South America exhibited alternative tree-cover states, while dryland ecosystems at the global scale and in Africa, Europe, and North America did not. Livestock density and the aridity index appeared to be the primary drivers of these states in the regions where they occurred. This study highlights the importance of considering the variability in dryland vegetation states across different scales and regions, as small-scale processes may not always accurately predict large-scale dynamics. By examining dryland woody vegetation at both global and continental scales, our work contributes to a more comprehensive understanding of the factors that affect the tree-cover states in these ecosystems.
Estimation of the Peak Runoff Coefficient on Small Catchments in Slovakia
Authors: Paulíková Lynda , Kohnová Silvia , Výleta Roman
Published: March 2024

Runoff is one of the essential indicators for designing measures that retain or safely divert water in the country. However, in the 21st century, rural basins face changes caused by climate or land use. These alters force society to think about the transformation that time brings and to change the view on some parameters of the country's functioning within the outflow processes. The presented contribution deals with runoff changes over the last decades, in which the difference in the values ​​of peak runoff coefficients in small watersheds is analysed using direct and indirect estimation methods.The first part of the study deals with the indirect approximate calculation of the peak runoff coefficient in 128 small catchments up to an area of 150 km2 (approx. 58 mi2 ) located on the territory of the Slovak Republic. Input data consisted of estimated concentration times according to Nash and Kirpich formulae, estimated design values for maximum floods and IDF curves for all available rain gauge stations in each analysed basin. The results were compared to previous studies.In the second part, for two selected basins (Parná – Horné Orešany and Belá – Liptovský Hrádok), we estimated the peak runoff coefficient using the direct method. The chosen watersheds represent different landscape structures, where the first is a lowland type, and the second a high-mountain type of landscape. The analysis was based on direct measurements of hourly peak flows from 1989 to 2021. The flood wave parameters for calculating the peak runoff coefficients were obtained by substituting the causative precipitation. These data were subsequently statistically analysed using the Johnson probability distribution. The peak runoff coefficient for a 100-year return period was separately modelled for the summer and winter periods in both basins and compared to the indirect estimation results.The study's results are intended to highlight the differences in the methods used to estimate peak runoff coefficients in small watersheds. AcknowledgementsThis study was supported by the Slovak Research and Development Agency under Contract VEGA Grant Agency No 1/0782/21. The authors thank the agencies for their research support.
Understanding the origin of dolomite in the sedimentary record: the contribution of clumped isotope thermometry.
Authors: Bernasconi Stefano , Rosskopf Ricarda , Looser Nathan , Hemingway Jordon
Published: March 2024

The formation of dolomite in the sediments of the Sabkha of Abu Dhabi was the subject of Judy’s PhD thesis and the question of the origin of dolomite remained at the center of her scientific interests throughout her career. The main focus was on the influence of microbial activity on dolomite formation, both in the field and through laboratory experiments. Over the years, Judy’s contributions particularly advanced our understanding of the role of microbes in the formation of dolomite.With the development of clumped isotope geochemistry, a new tool is now available to better characterize the conditions leading to the formation of dolomite in the geological record. This tool exploits the preference of13C-18O bonds in carbonate molecules to form with decreasing temperature and provides a thermometer that can be used to constrain the formation temperature and the oxygen isotope composition of the fluids involved in the precipitation of dolomite. The interpretation of dolomite clumped isotopes in the geological record, however, is complicated by the fact that early-diagenetic dolomite is generally poorly ordered and non-stoichiometric, and it converts to a more stable form during diagenesis. In this contribution we will present case studies from the Alps to show how the original clumped isotope compositions of dolomite are modified during diagenesis under different thermal regimes, and we will discuss the preservation of clumped isotope signatures in dolomite.
SEAS: a simulation system for forecasting the atmosphere-coupled ocean dynamics in the Southern EuropeAn Seas
Authors: Maicu Francesco , Pinardi Nadia , Guadi Silvio , Clementi Emanuela , Trotta Francesco , Coppini Giovanni
Published: March 2024

The prototype of a short-term forecasting system of the ocean dynamics of Southern European Seas (SEAS), was developed. It is based on a regional coupled ocean-atmosphere model, with NEMO and WRF codes implemented on the same computational grid, with 1/24° resolution, which encompasses Mediterranean Sea, Marmara Sea and Black Sea. The domain extends also westward and northward in the Atlantic Ocean to downscale properly the mid-latitudes atmospheric perturbations from the parent ECMWF HRES model.The forecasting uncertainty of the atmospheric regimes in such a complex Euro-Mediterranean region must be considered along with the uncertainties of the parametrizations of the surface processes at the ocean-atmosphere interface. Therefore, the goal of coupling oceanic and atmospheric models is to reduce these uncertainties and exploit the second type predictability to increase the forecast skills of the ocean dynamics.The uncoupled ocean model has been validated against Sea Surface Temperature (SST) satellite observed data, and the skills compared to those of the Copernicus Mediterranean Forecasting System (MedFS hereafter) both in the short-term forecast over two seasonal periods and in the simulation of the medicane Ianos.Various physical schemes, domain extensions, boundary, and initial conditions were initially tested using the uncoupled atmospheric model to obtain the best representation of the medicane Ianos. Furthermore, these experiments were also useful to determine the coupling strategy more appropriate to reduce the heat fluxes imbalance between the two components.The SST differences between coupled and uncoupled experiments are determined by the heat fluxes computation in the atmospheric component rather than using the MedFS bulk formulae implemented in the ocean model. These differences are largely dependent on the surface boundary layer scheme used in WRF, therefore, several coupled experiments were conducted.In terms of SST, the coupled model replicates the skills of the MedFS in the winter period while in the summer period the skills are worsened due to the larger heat fluxes. Numerical experiments focused on the parametrizations of the atmospheric boundary layer are still ongoing work.The skill of the coupled model in reproducing the observed SST during the medicane Ianos is comparable with the one of the uncoupled oceanic model in the Ionian Sea. In terms of heat fluxes, the coupling changes significantly the heat budget locally in the Ionian Sea, mainly through the latent heat flux and the shortwave radiation. The coupling is not that relevant for the intensification of the cyclone, whereas it enhances the representation of its path and the time of the landfall on the Ionian Islands.
Rainfall Microphysics and Instrument Measurement Assessments via Rainfall Simulators
Authors: Testik Firat Y. , Saha Rupayan , Rahman Kalimur
Published: March 2024

This study presents investigations on rainfall microphysical processes and ground-based rainfall instrument measurements through laboratory rainfall simulations with careful considerations for in-situ observations and validations.  Controlled laboratory rainfall experimentation has a pivotal role in systematic investigations to deepen our understanding of rainfall microphysical processes and the development, calibration, and assessment of rainfall instruments.  In the rainfall and related investigations in the PI’s laboratory over the past nearly two decades, we have utilized a variety of laboratory rainfall simulation setups, each featuring customized drop generators for the application, that were designed to address the specific aspects and objectives of the targeted research.  Here we will present our select experimental investigations on raindrop morphodynamics (shape and fall speed) and collisions as well as assessments of the OTT Parsivel2 disdrometer and OTT Pluvio2 rain gauge measurements.  Raindrop morphodynamics and collisions are of importance for various applications, including radar rainfall retrievals and hydrological modeling.  Parsivel2 and Pluvio2 are widely used ground-based instruments to monitor various precipitation quantities (e.g. raindrop size distribution, fall speed, and rainfall intensity, amount, and kinetic energy) that are of importance for a variety of rainfall- and water resources-related applications, including ground validation and soil erosion studies.  This material is based upon work supported by the National Science Foundation under Grants No. AGS-1741250 to the first author (FYT).
Machine Learning-based Mineral Prospectivity Mapping: Exploring the Role of Negative Training Labels to Enhance Predictive Models
Authors: Bay Nyah , Noh Kyubo , Parsasadr Mohammad , Swidinsky Andrei
Published: March 2024

Mineral Prospectivity Mapping (MPM) is an important tool to identify areas with significant potential to host mineral deposits. Recent advancements in computational sciences, especially the advent of Machine Learning (ML), have enhanced MPM's capabilities. ML techniques enable a higher degree of data integration and extraction compared to traditional statistical methods such as Weights of Evidence, enhancing the accuracy and efficiency of identifying mineral exploration zones. When using ML techniques for MPM, the influence of negative training labels (ie. barren areas with no mineralization) remains a neglected research area, and this study investigates the influence of such label selection to optimize predictive models for Canadian critical mineral exploration.
Previous approaches to ML-based MPM often adopted a random assignment of negative training labels wherever positive training labels were absent. This study aims to refine this method, striving for a more systematic approach in negative label selection. The evolution of MPM, transitioning from traditional statistical methods to modern ML algorithms, signifies a shift towards heightened accuracy and efficiency. Prior research underscores the importance of balanced representation between mineralized and non-mineralized labels in ML models. Techniques such as Synthetic Minority Over-Sampling (SMOTE) and Positive and Unlabelled Learning (PUL) have been highlighted in previous studies, emphasizing the necessity of effectively handling negative training labels to prevent biases and enhance model performance. While SMOTE and PUL synthetically balance datasets by either oversampling minority classes or considering only positive and unlabeled instances, this study focuses on leveraging public exploration data to identify real negative training labels and provide a more authentic representation of non-mineralized areas without synthetic augmentation.
Using datasets compiled by the Geological Survey of Canada containing discoveries & occurrences of magmatic Ni (±Cu ±Co ±PGE), this research incorporates geological, geochemical, and geophysical data from established sources. Public exploration data will be used to identify areas devoid of magmatic Ni (±Cu ±Co ±PGE). These locations will serve as negative training labels for this study. Our particular choice of ML model is a Gradient Boosting Machine (GBM), and validation involves comprehensive evaluation techniques such as confusion matrices and receiver operating characteristic curves to assess model performance.
Icequake source location using seismic data in Dålk Glacier, East Antarctica
Authors: Zhao Shun , Cao Zheyi , Gu Yuanyuan , Lv Chen , Ma Zhitu , Hao Tong , Qiao Gang , Wang Benfeng , Li Rongxing
Published: March 2024

Icequakes are closely associated with glacier movement and rupture, and their temporal and spatial distribution patterns can portray the dynamics of glaciers. In this study, we used the seismic data recorded by 34 short-period Smartsolo seismometers deployed in Dålk Glacier, East Antarctica for about 60 days to detect and locate icequakes. The array was deployed at the edge of the Dålk Glacier and across the grounding line previously generated by satellite observations. The recorded data were strongly affected by Antarctica storms and we selected two days with little wind noise for preliminary analysis. Using time-frequency analysis and particle motion, we found that the seismic events are either dominated by body waves or surface waves, which likely correspond to deep icequakes or near-surface crevasse icequakes. Since the propagation of surface waves is easier to analyze and possible detections of crevasse icequakes are more likely to be verified from satellite images, we chose to focus on surface wave signals in this preliminary analysis. We first filtered records to 5-20 Hz and manually examined records with clear surface wave arrivals. We then produced templates using these events to scan through our records. We successfully identified 89 events within the two-day period. Lastly, these signals were located using a grid-search approach for their latitudes and longitudes, together with an average group velocity for each event. Nearly half of the incidents were concentrated on the edges of rock outcrops, which suggests they were generated by the relative movement between the glacier and outcrops. The other half of the events was found in the eastern region, where a large number of surface crevasses were observed on satellite imagery. In addition, the optimal velocity from the grid search is ~2.8 km/s for events from the North and West, while the optimal velocity for events from the East is ~1.8 km/s. The difference in wave velocity suggests the existence of a boundary between rock and ice at a depth of about 100-150m within or near our seismometer array. By analyzing the amplitude variations of incidents in different directions recorded at various stations, we observed that this boundary is within our array and its location and geometry can be estimated. Compared to the grounding line predicted from satellite observations, our result shows that the boundary is offset to the East by ~100 m. The reason for this discrepancy will be further discussed in the meeting.
Response of calcareous nannoplankton to paleoenvironmental changes across the Aptian-Albian transition of the southern South Atlantic (Falkland Plateau, DSDP Site 511)
Authors: Bottini Cinzia , Bettoni Chiara , Erba Elisabetta , Herrle Jens
Published: March 2024

The late Aptian-early late Albian transition has been characterized by changes in surface water temperature and fertility recognized in several successions at low- and mid-latitudes. Less is known about paleoenvironmental conditions at higher latitudes. In this work we focused on the southern South Atlantic which is a key region to explore the Early Cretaceous oceanography and climate. We studied calcareous nannofossils in the Deep Sea Drilling Project (DSDP) Site 511, drilled on the Falkland Plateau, which yields one of the few sedimentary sequences at southern high-latitudes that records a relatively continuous upper Aptian–Albian sequence. Calcareous nannofossils were investigated to refine the biostratigraphy, reconstruct size variations of Watznaueria barnesiae and Biscutum constans and obtain relative abundances.The data collected indicate that responded to temperature and fertility fluctuations throughout the studied interval. Specifically, the temperature and nutrient index are suggestive of multiple variations in surface water conditions related either to global perturbations and local changes in the paleoceanography. Relatively lower temperature and fertility characterized the late Aptian. A brief warming phase is associated with the Aptian/Albian boundary followed by a moderate change in the assemblage composition in the early and early late Albian, with abundant cold-water species Repagulum parvidentatum and more abundant surface-water fertility species. Morphometric analyses indicate changes in W. barnesiae and B. constans average size which mostly follow the size patterns identified in the Tethys across the same stratigraphic interval suggestive to reflect a global response to paleoenvironmental changes occurred during this peculiar phase. W. barnesiae size variations are of less amplitude compared to B. constans and occur at different stratigraphic levels. Both species show smaller specimens in the late Aptian compared to the middle-late Aptian. Largest B. constansare identified in the early late Albian. A difference in the total average size of both species is also identified, with average larger specimens occurring in the Falkland compared to the Tethys.
Wide-area deformation surveying and Groundwater Volume Loss assessment in the North China Plain by Multi-track InSAR Observations and mechanical models
Authors: zhang xing , hu jun
Published: March 2024

The long-term over-extraction of groundwater in the North China Plain(NCP) has led to disasters such as ground subsidence, ground fissures, and seawater intrusion. These have posed serious threats to infrastructure, aquifer systems, and the ecological environment. By establishing a functional model of surface deformation and groundwater changes, we can enhance our understanding of the mechanisms behind ground subsidence and quantitatively assess how groundwater storage evolves under the dual influences of human activities and natural processes. InSAR (Interferometric Synthetic Aperture Radar) has proven to be the most effective tool for long-term、wide-area ground deformation monitoring and underground hydrological parameter inversion. Considering the characteristics of ground subsidence such as long-term, progressive, and wide distribution, in this study, eight stacks of 1496 Sentinel-1A/1B SAR scenes spanning from 2017 to 2023 were acquired in ascending mode along tracks T40 and T142. Through methods like (InSAR) time series analysis method、phase unwrapping correction and spatio-temporal smoothing fitting, we obtained a long-time-series high-precision LOS deformation field for the NCP. Secondly, by introducing the spatial domain network adjustment method, we can implement joint adjustment and correction of wide-area multi-map results to obtain a unified spatio-temporal reference for the NCP's wide-area InSAR vertical ground deformation field. Finally, we use the InSAR-VSM model based on elastic half-space and the one-dimensional poroelastic model considering elastic unloading to obtain independent quantitative estimates of groundwater loss in NCP. For the first time, we have reduced the spatial resolution of groundwater reserves inversion in the NCP from hundreds of kilometers to several kilometers, breaking through the bottleneck of insufficient spatial resolution in groundwater hydrological research. By integrating the South-to-North Water Diversion Project, groundwater extraction policies in the NCP, meteorological datasets, and groundwater level data, we have found that there are significant differences in the response mechanisms of groundwater and land subsidence between piedmont plains and flood plains in the NCP. Our data and results have enhanced our understanding of changes in groundwater storage in the North China Plain and provide scientific support for scientifically managing groundwater resources and carrying out related work on preventing and mitigating ground subsidence disasters.
Multi-source in situ and satellite variational data assimilation into a fully distributed hydrological model for floods and droughts modeling over poorly gauged and ungauged areas
Authors: Ettalbi Mouad , Garambois Pierre-Andre , Baghdadi Nicolas , Ferreira Emmanuel , Huynh Ngo-Nghi-Truyen
Published: March 2024

Estimating water flows and stocks in surface hydrology is crucial for addressing important socio-economic issues, such as managing water resources and predicting extreme events like floods and droughts. These challenges become more significant with the ongoing global climate change, which may intensify the hydrological cycle. Advanced modeling tools are necessary for making precise and reliable local forecasts. However, hydrological models, regardless of their complexity and status, encounter difficulties in accurately and reliably predicting quantities of interest such as river flows or soil moisture states, and in accounting for meteorological-climatic effects on hydrology. Given the complexity of the physical processes involved and their heterogeneous and limited observability, hydrological modeling is a challenging task, and internal flows often have significant uncertainties. These uncertainties could be reduced by integrating new observations from remote sensing applied to continental surfaces, which is rapidly evolving. A variety of satellites and sensors now allow the observation of watershed surface characteristics and hydrological responses with increasing spatial-temporal resolutions. In particular, products of soil moisture, evaporation, and land use are now available at relatively high spatial-temporal resolution. This work focuses on improving the integration of satellite and in-situ land surface data into spatially distributed hydrological models. The Hybrid Data Assimilation and Parameter Regionalization (HDA-PR) approach incorporating learnable regionalization mappings, based on neural networks into the differentiable hydrological model SMASH, is modified to account for satellite moisture maps in addition to discharge at gauging stations and basins physical descriptors maps. Regional optimizations are performed on flash-flood-prone areas located in the South of France and their accuracy and robustness is evaluated in terms of simulated discharge and moisture against observations. 
Investigating the applicability of long short-term memory model for streamflow prediction 
Authors: Tanhapour Mitra , Hlavcova Kamila , Kohnova Silvia , Shakibian Hadi , Soltani Jaber , Malekmohammadi Bahram
Published: March 2024

Streamflow prediction, especially extreme events, poses a significant challenge due to the intricate and unpredictable nature of the rainfall-runoff process. Recently, promising results have been observed in time series problems by applying deep learning methods, including Long Short Memory (LSTM) and sequential modelling. This study investigates the application of the LSTM network to predict daily streamflow in the Dez River basin, Iran, during 2012–2019. Accordingly, observed precipitation, temperature, empirical evapotranspiration, and runoff were utilized as predictor variables. The performance of the LSTM model was compared with an established process-based approach, the Hron rainfall-runoff model, which served as a benchmark to evaluate the effectiveness of this innovative model. The models were evaluated using Kling-Gupta efficiency (KGE), Nash-Sutcliff efficiency coefficient (NSE), normalized root mean square error (NRMSE), and mean absolute percentage error (MAPE). Through evaluation and analysis, the NSE and MAPE indices were, respectively, 0.95 and 15.6% for the LSTM model in the validation stage. The results demonstrated that the LSTM model performed better than the Hron model in predicting daily streamflow. The superior performance of the LSTM network represents its efficiency in capturing and utilizing inherent temporal dependencies in hydrological data. This finding highlights the potential of the proposed model for improving the accuracy and reliability of real-time hydrological forecasts.
Quantifying landslide erosion rates over millennial timescales in the Southern Alps and Fiordland, New Zealand
Authors: Roda-Boluda Duna , Schildgen Taylor , Lupker Maarten , Bufe Aaron , Søndergaard Anne Sofie , Haghipour Negar , Prancevic Jeff , Tofelde Stefanie , Wittmann Hella , Hovius Niels
Published: March 2024

Landslides are a major erosional mechanism in mountain landscapes, play a crucial role in source-to-sink systems by delivering coarse sediment, and constitute a major geohazard. However, quantifying long-term (>102 yrs) landslide sediment fluxes is challenging, because remote sensing offers high-resolution constraints only over the last few years or decades, and landslide scars and deposits are often obliterated in
Crustal structure along the island arc of the Java subduction zone from receiver functions and its tectonic implications
Authors: Liu Zhangju , Kong Fansheng , Yu Youqiang , Li Jiabiao
Published: March 2024

Crustal thickness (H) and bulk Vp/Vs ratio (k) are widely used to understand crustal deformation and probe tectonic evolution of plates. In the study, 17 pairs of H and k are obtained based on the H-k stacking of receiver functions in the Java subduction zone, among which 14 pairs are corrected for sedimentary effect by applying a resonance removal procedure. The measured crustal thicknesses of Java Island range from 30.2 to 36.5 km, with an average of 32.5 km, and the crustal thicknesses of the Lesser Sunda Islands are strongly variable, ranging from 20.1 to 34.1 km. The crust thickness in the island arc is consistent with that of the extended crust, and the crust thickness of Java Island is on average thicker than that of the Lesser Sunda Islands. This characteristic is consistent with the current extension environment caused by trench retreat and crustal movement, and the stretching stress increases from west to east. The study area has extremely high Vp/Vs ratios, ranging from 1.80 in western Java, to an average of 2.0 in central and eastern Java, and up to 2.2 on average in the Lesser Sunda Islands. The Vp/Vs ratios increase from west to east, which we attribute to: (1) The history of block collision and volcanic activity of the Java subduction zone gradually decrease from west to east, resulting in relatively weak crustal magmatic activity in western Java; (2) The crust of the Lesser Sunda Islands is subjected to the stronger stretching stress, which makes it easier for the mantle material intrusion; (3) The significant variation of crustal thicknesses and widespread lateral crustal dips and faults of the Lesser Sunda Islands provide good vertical channels for the intrusion of basic mantle materials.
Intensification of the hydrological and carbon cycles linked to volcanism during theCarnian Pluvial Episode
Authors: Xu Yanhua , He Dengfa
Published: March 2024

Extreme hydroclimatic changes in the geological record are commonly associated with voluminous greenhouse gas emissions from large igneous provinces. A possible example of this is the Carnian Pluvial Episode (CPE) of the Late Triassic (~233 Ma). The precise temporal relationship between increased hydrological cycling and volcanism at the CPE is unclear, however, as most studies have focused on marine records that provide only indirect and likely delayed evidence of hydrological changes on land. Here we present a multiproxy analysis (including organic carbon isotopes, mercury (Hg) concentrations and isotopes, trace elements, and zircon U-Pb dating) of a terrestrial sedimentary record of the Carnian deposited in the northeastern Paleo-Tethys. We can identify the onset of volcanic activity in this record based on Hg enrichment and near-zero mass independent fractionation of Hg isotopes, which serve as a proxy for volcanism, and find that this onset is broadly coeval with the onset of the CPE and enhanced terrestrial runoff and rapid lake expansion. Enhanced hydrological cycling persisted throughout the CPE. Our results provide a direct link between volcanism and its impact on the hydrological and carbon cycles.
On the radiocesium distribution on the Romanian territory 30 years after the Chernobyl disasters
Authors: Duliu Octavian G. , Blebea-Apostu Ana-Maria , Margineanau Romul Mircea , Persa Diana , Gomoiu Maria-Claudia
Published: March 2024

The Chernobyl 1986 accident, considered one of the worst of its kind, occupies the highest 7th position on the seven levels IAEA International Nuclear and Radiological Event Scale. Following the thermal explosions which took parts, an impressive amount of new and spent nuclear fuel, rich in fission and neutron activation products was dispersed into the atmosphere at an altitude up to a few km, but without reaching the stratosphere. In this way, about 20 to 40 % of the total radiocesium inventory estimated to be 280 PBq of 137Cs was transported by the atmospheric circulation contaminating significant areas of Ukraine, Belarus, Russia, Scandinavian countries, Central and Eastern Europe. Its presence was signaled also in Japan, Canada, and the United States.Due to the geographical position of Romania in the vicinity of Ukraine, the total 137Cs contamination of Romanian territory was estimated immediately after the Chernobyl accident at 51 ± 2 TBq, an estimation based on more detailed measurements performed during the 1993 y on 62 locations.Under these circumstances, and for a more accurate estimation of the 137Cs contamination, 747 soil samples covering the entire Romanian territory were collected, and the radiocesium inventory was measured by gamma-ray high-resolution spectroscopy performed in the low backgrounder laboratory located in the Slanic-Prahova former salt mine. Soil sampling and radiometric measurements were performed between 2016 and 2018 years, all data being recalculated for May 2016, i.e. 30 years after the Chernobyl accident.The results showed for the 2016 radiocesium distribution an irregular pattern containing four maxima of which positions were quite different from the 1993 ones. Concerning the 137Cs inventory, its total value decreased from 43 ± 2 TBq in May 1993 to 14.1± 0.7 TBq in May 2016, i.e. by a factor of 3 ± 0.3, twice of natural disintegration. This finding could be explained by taking into account that a significant amount of radiocesium was washed out by precipitation and, in a lower measure, was incorporated into plants.The same data permitted evaluation of the total contribution of 137Cs to the population exposure. Accordingly, in 1993 and even more so in 2016, the average supplementary annual effective dose did not exceed 1 mSv, i.e. the maximum annual effective dose considered not harmful for the unexposed population.
Urgency of Climate Change through the lens of COVID-19 Pandemic: the case of heat-related mortality
Authors: Batibeniz Fulden , Seneviratne Sonia Isabelle , Jha Srinidhi , Ribeiro Andreia , Gutierrez Laura Suarez , Raible Christoph C. , Armstrong Ben , Bell Michelle L. , Lavigne Eric , Gasparrini Antonio , Guo Yuming , Hashizume Masahiro , Masselot Pierre , Pereira da Silva Susana , Royé Dominic , Sera Francesco , Tong Shilu , Urban Aleš , Vicedo-Cabrera Ana M. ,   Multi-Country Multi-City Collaborative Research Network
Published: March 2024

The COVID-19 pandemic and climate change are both urgent global health concerns. However, their impact on human lives has not been compared on the same scale. In this study, we compared mortality due to heat with COVID-19 in 38 cities worldwide, considering different levels of global warming (+1°C, +1.5°C, +2°C, and +3°C). Our findings reveal that even at a global warming level of +1.0ºC, 6 cities are already at a point where heat-related deaths could equal COVID-19 deaths within 15 years. Regardless of high or low COVID-19 mortality in the cities, the number of years to reach the level of COVID-19 mortality decreases with higher global warming levels. In 18.4% to 47.4% of the cities, heat-related mortality is projected to equal COVID-19 mortality within 15 years, ranging from +1.0ºC to +3.0ºC of global warming. The vulnerability to climate change varies among regions, with European, Mediterranean, and North American cities experiencing a significant rise in heat-related mortality with higher global warming levels. It is important to note that the given number of years represents the time required to reach COVID-19 mortality. However, unlike the peak and decline of COVID-19, climate change-driven heat-related deaths will persistently worsen unless substantial adaptation measures are taken. This emphasizes the crucial need to integrate climate change into public health discourse and policy.
Assessment of variability in urban HONO using MAX-DOAS measurements in Central London
Authors: Gershenson-Smith Eleanor , Marais Eloise A. , Ryan Robert G. , Lu Gongda
Published: March 2024

In polluted cities with large sources of NOx, rapid photolysis of nitrous acid (HONO) may be a major daytime source of the main atmospheric oxidant, OH. Current understanding of urban HONO is problematic. Its abundance is generally underestimated by models, and urban and rural networks. Campaigns with in situ instruments routinely identify a mystery midday HONO source. These measurements do not directly measure HONO and offer no insight into its vertical distribution. We use remotely sensed daytime differential slant column density (dSCD) measurements of HONO from a Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument which was installed on a 60 m rooftop during summer 2022 on the Bloomsbury University College London (UCL) campus. Modelled (GEOS-Chem) and surface network measurements of air quality and meteorology are used to characterise conditions conducive to HONO detection. To be detected, dSCDs must exceed the detection limit, which we define as 2 times the root mean square of the fit of residuals divided by the maximum absorption cross section of HONO. We find that MAX-DOAS HONO dSCDs at elevation angles measuring the lowest layers of the atmosphere are only ever above the instrument detection limit in winter mornings (8:30 am–12:00 pm local time), suggesting substantial nighttime accumulation of HONO. This early morning HONO decreases rapidly (within 3-4 hours) to below detection after sunrise. Consistent characteristics of these mornings include cloud-free, cold (< 0°C) and calm conditions (wind speeds < 2.5 m s-1), a shallow boundary layer (< 100 m), substantial surface ozone depletion (< 10 µg m-3), and relatively large contribution of NO to total NOx (NO/NOx mass ratio ³ 0.3). Work is underway to further characterise urban HONO using 190 m measurements of NOx from the Central London BT Tower observatory and assess the reaction kinetics balancing HONO loss and formation. New knowledge of HONO gained from MAX-DOAS measurements will then be used to evaluate best understanding of urban HONO as simulated with the GEOS-Chem model.
Analysis of dike-induced stresses and deformation: new insights from Mt. Etna and SW Iceland
Authors: Corti Noemi , Tibaldi Alessandro , Bonali Fabio Luca
Published: March 2024

During eruptions, magma arrives at the surface through vertical dikes. However, dikes often arrest in the crust, not feeding an eruption. Moreover, their emplacement causes a concentration of tensile and shear stresses in the host rock, that can lead to fracturing and/or faulting at the topographic surface. The relation between magma intrusion and dike-induced surface deformation has been analysed in the last decades through analytical, analogue and numerical models, but mostly considering an elastic and homogeneous half-space. Realistic data should therefore be considered to overcome this limitation.For this reason, in this work, field structural data are used as inputs for numerical modelling. Three case studies, all affected by shallow dike emplacement, are considered: the 1928 and 1971 eruptive fissures on Mt. Etna (Italy), and the Younger Stampar eruptive fissure in SW Iceland. On Mt. Etna, dike-induced brittle deformation is visible at the surface, in plan view for both cases, and in section view for the 1971 case study. In Iceland, two dikes (one feeder and one arrested) are exposed along a cliff; the tip of the arrested dike is only 5 m below the surface, but no brittle deformation is observed. These case studies allow us to investigate the parameters that i) favour/inhibit dike-induced brittle deformation at the surface, ii) affect the geometry of dike-induced graben faults, and iii) promote dike arrest at shallow depths.We collected structural data integrating classical fieldwork and remote sensing analyses, using high-resolution 2D and 3D models, reconstructed through Structure from Motion photogrammetry from drone images and historical aerial photos. We used all these structural data as inputs for 2D Finite Element Method numerical models, using the software COMSOL Multiphysics. In the models, sensitivity analyses were run to analyse the parameters that affect dike propagation and the induced surface deformation.This work underlines the role of layering on the formation of stress barriers and on the distribution of dike-induced stresses, that concentrate in stiffer materials and are suppressed in softer layers. Furthermore, it confirms the effects of dike overpressure and inclination on its propagation and on dike-induced stresses. Topography also affects the dike propagation path and the geometry of dike-induced graben faults. Finally, the role of lateral compression induced by nearby previous intrusions is investigated, showing how this can promote dike arrest and the lack of brittle deformation.
Surface forcing controls on the volume and heat content of subtropical and subpolar mode waters over the global ocean
Authors: Pimm Ciara , Williams Richard , Jones Dani , Meijers Andrew
Published: March 2024

Mode waters provide an important role within the climate system, sequestering large amounts of heat and anthropogenic carbon and play a key role in the transport of these properties around the globe. Our aim is to assess the roles of local versus remote surface forcing in controlling the properties of mode waters over the northern Atlantic and Pacific basins and the Southern Ocean. A set of adjoint sensitivity experiments are conducted using the ECCOv4r4 state estimate to assess the impacts of surface heat flux, freshwater flux, and wind stresses on the volume and heat content of mode waters in density space. Mode waters are identified using areas of deep winter mixed layers and their characteristic temperature, stratification, and neutral density properties. The adjoint modelling approach calculates time-evolving sensitivity maps that identify where and when specific surface forcing impacts properties in the mode water formation sites. The sensitivity analysis reveals the dominance of local forcing from surface heat fluxes with surface cooling initially increasing volume. On longer time scales, the sensitivities have differing responses to surface forcing including surface heat loss leading to a delayed restratification due to a haline contribution after a thermal contribution is effectively damped. The responses of the mode waters to surface forcing are then compared across their formation sites, in the northern basins involving western boundary currents and gyre interiors and in the Southern Ocean involving the Antarctic Circumpolar Current.
Demonstrating the potential of km-scale multi-annual coupled global simulations in nextGEMS: a (urban) surface perspective
Authors: Pedruzo-Bagazgoitia Xabier , Becker Tobias , Milinski Sebastian , Rackow Thomas , Sandu Irina , Boussetta Souhail , Dutra Emanuel , Hadade Ioan , Martins Joao , McNorton Joe , Sützl Birgit , Wedi Nils
Published: March 2024

The nextGEMS project is dedicated to develop global coupled earth-system models for multidecadal climate projections at a kilometre-scale resolution. By harnessing the strengths of high spatial resolution, the project seeks to improve the representation of physical processes and provide climate information at spatial scales that align with real-world measurements. Preparing for 30-year production runs, nextGEMS has achieved significant milestones, including the successful completion of five-year global coupled runs with a 5 km spatial resolution by two different Earth-System models: ICON, and ECMWF’s Integrated Forecasting System (IFS) coupled to the sea ice-ocean model FESOM. In this work we focus on the km-scale IFS-FESOM configuration, along with a comparable set of coarser IFS simulations coupled to either FESOM or NEMO ocean models.We first provide a brief overview of the most relevant scientific modifications on IFS and FESOM through the development cycles needed to perform multi-annual simulations: a reduction of the global water and energy imbalance by orders of magnitude, as well as the modification in cloud physics parameters to provide a stable climate, improved coupling of ocean surface currents and fluxes, and the addition of improved high-resolution land use and land cover maps. We further investigate the impact that the new refined surface maps have on the representation of climate at the surface and near-surface. We first explore the spatio-temporal surface-atmosphere coupling in these km-scale simulations. We then focus on more local phenomena: In particular, we pioneer the study of urban climate via coupled global multiannual simulations and explore surface-atmosphere interactions over urbanized areas, by combining refined land use/land cover maps with the active urban scheme in IFS. We find a more realistic spatial distribution of surface temperature in both urban and rural areas, especially noticeable at spatial resolutions of 9km and finer. By showing that the diurnal cycle of urban heat island intensity exhibits improved accuracy in numerous large European urban areas, our global simulations can provide local granularity at the scale of individual cities The enhancements in representing urban climate features are quantified through reduced bias, root-mean square error, and increased correlation with successively increasing model resolution.
Using ambient noise to study the co-seismic and post-seismic velocity changes of the 2021 Yangbi MS 6.4 earthquake in Yunnan, China
Authors: An Yanru , Wang Weitao , Yang Wei , Jiang Haikun , Yang Jun , Li Xiaobin , Pan Rui
Published: March 2024

Seismic velocity change is a good indicator reflecting the stress state variation of the underground media. Therefore, seismogenic process could be effectively revealed by the velocity change calculation. Based on the seismic ambient noise interferometry, we study the co-seismic velocity change and post-seismic recovery process of the 21 May 2021 MS6.4 Yangbi earthquake using the continuous records from 16 stations within 50km of the epicenter. The results show that the relative velocity changes between the station pairs (dv/vpair) decrease significantly after the mainshock. The amplitude ranges from -0.29% to -0.02% and decreases with the increase of station spacing. The relative velocity changes of each station (dv/vstation) obtained by linear regression range from -0.16% to -0.02%, and are generally negatively correlated with the epicenter distance. It is notable that the measured co-seismic velocity changes are mainly originated from the shallow media (≤2km). Such changes are considered to be caused by both static and dynamic strain, but the primary controlling factor is rock fragmentation and large-scale adjustment of stress produced by strong ground motion. In addition, dv/vstation located at the northern stations far from the epicenter have the largest drop values, demonstrating that they are more sensitive to stress disturbances. This may be related to the distribution of thermal fluids below these stations. The results of velocity changes indicate that around the study area the seismic velocity reached its minimum value within a few days after the mainshock. The value then gradually recovered, reaching the pre-seismic level around August, which characterizes the healing process of broken rocks. In this study, ambient noise interferometry has been effectively applied to measure the velocity changes during and after the Yangbi earthquake, and the results show that co-seismic velocity changes are jointly controlled by various factors including the fracture degree of the fault zone, dynamic strain, and the existence of fluids.