bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature responses of leaf respiration in light and darkness are similar and modulated by leaf development
Authors: Zheng Ding Ming , Wang Xuming , Tcherkez Guillaume , Gong Xiao Ying
Published: March 2024

In the context of global warming, temperature responses of leaf respiration (R) in light and darkness (RL and RDk) are essential to models of global carbon dynamics. Many models rely on constant thermal sensitivity (characterized by Q10) of leaf respiration. However, it remains unclear whether Q10 is similar for RL and RDk, given the differences in the rate and pathways of respiration between light and dark. Warm season growth causes thermal acclimation of R, and leaf development stage also affects R. It is uncertain if these factors influence the temperature response of R, which hinders the development of respiration models.Uncertainty in temperature responses of RL can also be associated with methodology. Recently, the Kok method has been improved by combining chlorophyll fluorescence and gas exchange to estimate RL. These advances have improved the accuracy of RL estimates.In this study, we developed a new method, the Kok-iterCc method. Using three methods (the Kok, Yin and Kok-iterCc methods), we measured the temperature response of RL and RDk in leaves of different leaf development stages (immature and mature) of two evergreen tree species (Castanopsis carlesii and Ormosia henryi) in two seasons (winter and summer). Q10 and basal respiration rate (R25) were then calculated.We found that, 1) When estimated by the Yin and Kok-iterCc methods, RL and RDk had similar Q10 (c. 2.5). The Kok method overestimated both Q10 and light inhibition of R. RL/RDk was not influenced by leaf temperature. 2) Acclimation of R in summer was associated with a decrease in R25 but not in Q10 in both species, which was related to changes in leaf nitrogen content between seasons. 3) Leaf development significantly affected R25 and Q10. Importantly, Q10 of RL and RDk was 40% higher in mature leaves than in immature leaves. The difference in contributions of growth and maintenance components of respiration are likely the main reason for the lower Q10 of growing leaves compared with mature leaves. Our results suggest that similar Q10 can be used to model RL and RDk, while leaf development related changes in Q10 require special consideration in future respiration models. 
A simplified calculation method for high-steep soil slope stability due to groundwater rise from irrigation
Authors: Zhuang Jianqi
Published: March 2024

The stability assessment of high-steep soil slopes remains a substantial challenge in slope engineering, especially in areas affected by groundwater. Research on the occurrence and development characteristics of high-steep soil slopes on the Heifangtai loess tableland, influenced by groundwater, reveals that groundwater is the critical factor impacting their stability. Given the shortcomings of commonly used calculation methods for assessing the stability of high-steep soil slopes, based on the Rankine earth pressure, the equilibrium conditions, and the strength failure criterion, a simplified calculation method for high-steep soil slope stability is proposed considering the typical characteristic that the failure surface of the high-steep slope is a double-segment line. In order to consider the influence of groundwater on high-steep soil slopes, the critical groundwater level of the slope of the tableland edge was determined based on the slope stability model. The model built in this study is straightforward, and the results are consistent with slope comparisons from other models, which modified the shortcomings of the existing model, such as the relatively concentrated and smaller stability coefficient. The critical groundwater level prediction model was applied to the Heifangtai tableland to verify the feasibility of the prediction model and point out the three high-risk points along the Heifangtai tableland. The results of this study provide a reference for stability calculations of high-steep soil slopes and a basis for the stability evaluation of slopes along the loess tableland impacted by rising groundwater.
What controls carbon and nitrogen allocation in montane vegetation: A case study from the Himalayas 
Authors: Sanyal Prasanta , Dasgupta Bibhasvata
Published: March 2024

Plants play a critical role in the surficial environment, influencing energy transfer, the global carbon (C) and nitrogen (N) cycles, and climate change. Knowledge of botanical and climatic controls on terrestrial C and N-cycling within and across ecosystems is central to understanding plant ecophysiology. In this study, we examined the effects of climate and forest composition on plant C and N, and systematically measured foliar δ13C and δ15N along an altitudinal gradient ranging 1900 to 5200 m, across three transects spanning west to east Himalayas. Total C and N content in plants significantly decreased with altitude, except for TOC in central and western Himalayan gymnosperms. Precipitation and temperature gradients differentiated 76% of the variation in TN and δ15N, and only 2.5% in TOC and δ13C stocks in the Himalayan plants. We report a complex climatic and topographic control on the C and N allocation in montane ecosystems, quantified via isotopic signature and abundance, linking plant ecophysiology with resource availability. C and N being complementary in several foliar biochemical processes, their mutual abundance was realised, examined and inferred in previously unexplored montane ecosystems and climate. In addition, the spatial distribution of foliar-isotope-abundance helped cluster plant responses, eventually leading to the construction of a spatially comprehensive map known as a dual isoscape.
Geochemistry π: Automated Machine Learning Python Framework for Tabular Data
Authors: Zhao Jianming , ZhangZhou Johnny , He Can , Lyu Yang ,   ZJU Earth Data Group
Published: March 2024

Machine learning has significantly advanced geochemistry research, but its implementation can be arduous and time-consuming. In response to this challenge, we introduce Geochemistry π, an open-source automated machine learning Python framework. With Geochemistry π, geochemists can effortlessly process tabulated data and execute machine learning algorithms by selecting preferred options. This streamlined process operates in a user-friendly question-and-answer format, eliminating the need for coding expertise. Following automatic or manual parameter adjustment, Geochemistry π furnishes users with comprehensive performance metrics and predictive outcomes for their machine learning models. Leveraging the scikit-learn library, Geochemistry π has developed a tailored automated workflow encompassing classification, regression, dimensionality reduction, and clustering algorithms. The framework’s extensibility and portability are enhanced through a modular pipeline architecture, segregating data handling from algorithm application. Geochemistry π’s Auto Machine Learning module integrates Cost-Frugal Optimization and Blended Search Strategy hyperparameter search methods from the A Fast and Lightweight Auto Machine Learning Library. Additionally, model parameter optimization is expedited using the Ray distributed computing framework. Efficient machine learning lifecycle management is facilitated through integration with the MLflow library, allowing users to compare multiple trained models at various scales and manage generated data and visualizations. To enhance accessibility, Geochemistry π separates front-end and back-end frameworks, culminating in a user-friendly web portal. This portal not only showcases the machine learning model but also presents the data science workflow, making it accessible to both researchers and developers. In summary, Geochemistry π offers a robust Python framework that empowers users and developers to significantly enhance their data mining efficiency, with options for both online and offline operation.
 Seismic geomorphology of buried channel systems in the western South Huanghai Sea: retrodiction for paleoenvironments
Authors: Kong Xianghuai , Liu Jian
Published: March 2024

Quantitative morphologic analysis of shallowly buried, dendritic channel systems in the continental shelf off the abandoned Huanghe River (Yellow River) mouth has been made based on interpretation of high resolution seismic profiles, with the attempt to estimate the paleo-hydrologic parameters when the incised-channels formed, then assess the paleo-environment. The results indicate that the buried channel systems were formed about 44 cal ka BP with dendritic drainage pattern when the shelf was subaerially exposed. The channel paleo-current velocities were sufficient to initiate and carry very coarse particles. And the paleo-flow is similar to the Changjiang River in the same period. Subsequently, the channel systems drowned and filled during the Holocene transgression with the sea level rise continuously. The study area has experienced great range of environments since the last glaciation, from exposed, fluvial and estuarine to fully marine.
Responses of outer radiation belt electron phase space densities to geomagnetic storms: A statistical analysis based on Van Allen Probes observations
Authors: Wang Xiaoyu , Cao Xing , Ni Binbin
Published: March 2024

Using Van Allen Probes observations spanning September 2012 to June 2019, we statistically investigate responses of electron phase space densities (PSDs) to 131 isolate storms in the Earth’s outer radiation belt. Electron PSDs for μ = 50-5000 MeV/G and K = 0.11 G1/2RE are calculated to evaluate three distinct responses (i.e., enhancement, depletion and no change), showing strong dependences on μ, L* and storm magnitude. Seed population is dominant by enhancement- and no change-type events, while relativistic and ultrarelativistic populations exhibit dynamical evolutions regardless of storm level. As μ increases, enhancement-type events decrease and tend to higher L*, while depletion-type events are increased for relativistic and ultrarelativistic populations. Comparing with small storms, large storms tangibly increase enhancement-type events at broader L* resulting in peak occurrences of relativistic population in the heart of the Earth’s other radiation belt. In contrast, large storms are likely decreasing ~20% depletion-type events for relativistic population and ~10% for ultrarelativistic population, as well as occurring at lower L*. No change-type events are primarily concentrated on inner part of the Earth’s other radiation belt, the L* coverages of which are sensitive to storm magnitude, especially for relativistic and ultrarelativistic populations. We also suggested that large storms are potentially accompanied by more intense solar and geomagnetic activities than small storms. While solar wind speed performs similarly for both storm levels and exhibits μ-dependent variations. Our results improve the current studies of storm-time electron PSD responses, thus providing a more comprehensive investigation to in-depth understanding dynamics of the radiation belt electrons during different storm levels.
Drop penetration dynamics of rhamnolipid biosurfactant on peat
Authors: Duggireddy ReddyPrasanna , Arye Gilboa
Published: March 2024

Peat and peat-based growing media continue to serve as the major constituents in soil-less cultivation due to their favorable physical and hydraulic characteristics. However, the substrate’s inherent high organic nature, and the intensive dehydration  process employed to compact peat into bales for cost effective transportation , results in the substrate development of water repellency. Consequently, this alters the media's optimal physical and hydraulic characteristics and reducing productivity in cultivation systems. Efforts to ameliorate substrate water repellency have predominantly involved the application of wetting agents, primarily focusing on their effect on various plant growth parameters. Synthetic surfactants were proposed to treat the substrate’s water repellency, but given the environmental concerns, alternative strategies become imperative. Biosurfactants, particularly rhamnolipids, have emerged as intriguing compounds at the scientific and commercial levels. Nonetheless, comprehensive quantitative investigations on the rate and extent of wetting and spreading behaviors of aqueous biosurfactant solutions which is essential for understanding drop penetration dynamics on peat, are currently inadequate. In this regard, the main objective of this study is to quantify the drop penetration dynamics of biosurfactants on peat porous substrate under different initial moisture conditions and on peat pellet compressed at different pressures to account for different densities and surface roughness. The study involved measurements of contact angle (CA), drop height, base diameter, and volume of aqueous biosurfactant solutions on prewetted peat with water and biosurfactant and peat pellets using optical tensiometer (OCA-15, Data Physics, Germany). The results demonstrate the relative degree of water repellency with the droplet dynamics of water exhibiting a CA of ~1200 and relatively constant drop height and base diameter. Conversely, biosurfactant droplets reduced drop height and volume, and the CA of 1200-800 was dependent on prewetting conditions. Furthermore, drop penetration dynamics into pellet peat highlighted the role of surface roughness with higher CA at lower compression pressure (69 bars) relative to higher one (517 bars). Furthermore, the study revealed a pronounced dependence on biosurfactant solution surface tension (ϒlv), with negligible CA changes within the higher ϒlv ( from 72 down to 41mN/m) domain and significant alterations within the lower ϒlv (down to 33 mN/m) domain. These outcomes underscore the effectiveness of rhamnolipid biosurfactant in aiding drop infiltration into initially hydrophobic peat, implying its role in aiding to peat wettability.Keywords: Peat, Pellets, water repellency, contact angle, surface tension, rhamnolipid biosurfactant, droplet dynamics.
Comparing the eddy covariance and gradient methods for measuring water and heat fluxes in paddy fields
Authors: Zhao Yanchao , Wu Jingwei
Published: March 2024

Rice is distributed worldwide; thus, quantitative analyses of water and heat fluxes between the land and air in paddy fields are vital for understanding basin-scale water cycles. In this study, eddy covariance and meteorological gradient systems on a 20-meter flux tower in the Jianghan Plain, Yangtze River Basin, China, were used to measure turbulent and meteorological parameters in paddy fields in 2021. Three micrometeorological methods, namely the eddy covariance (EC), Bowen Ratio-Energy Balance (BREB), and aerodynamic (AERO) methods, were used to calculate the latent heat flux (LE) and sensible heat flux (H); BREB and AERO are collectively referred to as gradient methods. The effects of measurement heights, growth stage, and weather conditions on the consistency among them were analyzed. The difference in meteorological measurement heights affected the results of gradient methods. Among the five height combinations, the error in the 2 and 4 m combination was the smallest, and the coefficients of determination of LEEC–LEBREB/AERO and HEC–HBREB/AERO reached 0.96 and 0.84, respectively. The stratification of the near-surface layer was formed due to the heterogeneous underlying surface of the experimental area, and the instrument needed to be installed within the range between roughness layer and new equilibrium layer. The height difference of gradient methods can be amplified within this range to avoid the influence of instrument resolution. The difference among methods was affected by growth stage, and weather conditions (sunny, cloudy, rainy days and different wind speed class). Both factors influenced atmospheric stability, and the error was the maximum in neutral stratification. This study provides a reference for the selection of flux calculation methods and error analyses for paddy fields in humid areas.Keywords: Paddy fields, Eddy covariance, Bowen Ratio-Energy Balance, Aerodynamics, Latent heat flux, Sensible heat flux
Systemic comparisons of the adaptations in symbiotic bathymodiolin mussels from diverse stages of hydrothermal vents and cold seeps 
Authors: Zhao Ruoxuan , Xu Jianzhou , Di Yanan
Published: March 2024

Hydrothermal vents (HVs) and cold seeps (CSs) are typical deep-sea extreme ecosystems with their own geochemical characteristics to supply the unique living conditions for local communities. Once the fluid vents stop emission, the dramatically environmental change would pose survival risks to deep-sea organisms and further shape the whole ecosystems. Up to now, limited knowledge was available to understand the biological responses and adaptive strategies to these extreme environments and their dual-state from active to extinct stage. In this study, bathymodiolin mussels, the dominant and successful species surviving in diverse deep-sea extreme ecosystems, were sampled from active and extinct HVs (Southwest Indian Ocean) or CSs (South China Sea) via two individual cruises. The transcriptomic analysis, determination of multiple biological indexes in stress defense and metabolic systems were conducted in both gill and digestive gland of mussels, together with the metagenomic analysis of symbionts in mussels. The results revealed the fluid-specific transcriptional regulation in mussels, addressing the autologous adaptations in successful antioxidant defense, varied energy utilization and key compounds (i.e. sulfur) metabolism due to distinction in different fluid environments. Coordinately, a heterologous adaptation, characterized by the functional compensation between symbionts and mussels in energy utilization, sulfur and carbon metabolism, was also evidenced by the bacterial metagenomic analysis in these chemosynthetic ecosystems. Taken together, a new insight was proposed that the dual-state of fluid vents drives symbiotic bathymodiolin mussels to develop an autologous and heterologous combined adaptation for successful survival.
‘EEmeetsEP’ - Helmholtz Earth and Environment meets the European Parliament and Stakeholders in Brussels
Authors: Athanase Marylou , Beamish Alison , Furst Séverine , Garcia-Garcia Almudena , Heidenreich Marie , Joerss Hanna , Klose Martina , Langhans Mirjam , Mengen David , Sielemann Katharina
Published: March 2024

In December 2023, the Helmholtz SynCom (Synthesis and Communication) traveled to Brussels with a delegation of selected scientists from the seven Helmholtz Earth and Environment Centres. This visit aimed at sharing current research findings and exchanging ideas with members of the European Parliament and other key stakeholders. The agenda included meetings with various entities such as the European Commission’s Directorate-General for Defence Industry and Space (DG DEFIS), the Directorate-General for Climate Action (DG CLIMA), the European Space Agency (ESA), and members of the European Parliament Niklas Nienaß and Jutta Paulus. This trip proved to be a valuable opportunity to connect European environmental and climate policy with fundamental research. When communicating scientific research, the importance of selecting a format suitable for the targeted audience constituted a key point. We discuss the lessons learned, and needs for user-oriented innovative tools for public outreach and for supporting policy decisions. Our exchanges also covered the potential impact of ongoing and upcoming European projects, like satellite-based Earth Observation missions and Digital Twins of the Earth, in providing crucial data for science-backed regulations. Lastly, we address the challenges faced in policymaking and the hurdles in integrating scientific discoveries into political decisions: we report suggested possibilities of including policy makers or the consideration of current regulatory questions within research projects.
Tracing the opening and connectivity of the South Atlantic with Sr and Os isotopes
Authors: Cardoso Dantas Rafaela , Flecker Rachel , Parkinson Ian , Tucker Maurice , Palcu Dan , Meijer Paul , Pires Negrão André , Jovane Luigi
Published: March 2024

The temporal and geological characteristics surrounding the initiation of the Proto-South Atlantic in the Early Cretaceous are presently unclear, marked by potential marine ingressions from both the northern Tethys- and the southern-ocean, ultimately culminating in the generation of immense salt deposits. The Araripe Basin in Northeast Brazil contains crucial outcropping records of these phenomena with its origin and development intricately linked to the tectonic forces orchestrating the disintegration of the Gondwana Supercontinent. The basin underwent distinct tectonic phases, transitioning from a pre-rift continental environment to a syn-rift lacustrine setting, and finally to evaporitic systems in the post-rift/sag phase.The post-rift stage is notably represented by the Santana Group, which chronicles significant environmental shifts, including the potential existence of a seaway linking the waters of the Tethys to the Proto-South Atlantic, intermittent marine incursions, and the presence of substantial evaporite layers. Despite extensive study, the paleoenvironment of this unit remains contentious, with hypotheses ranging from epicontinental sea to a basin with non-marine and transitional environments under marine influence.To address this ambiguity, we employ geochemical, paleomagnetic, and isotopic records (strontium 87Sr/86Sr and osmium 187Os/188Os) as indicators of hydrological connectivity. These tools serve as invaluable aids in reconstructing the paleoenvironment during the deposition of both pre- and post-salt phases in the basin. Keywords: Salt giant, South Atlantic opening, marine gateways, strontium isotopes, osmium isotopes
Ocean-surface wave measurements using scintillation theories on seaborne and coastal software-defined GPS and SBAS reflectometry observations
Authors: Tsai Lung-Chih , Hwa Chien , Su Shin-Yi , Lv Jun-Xian
Published: March 2024

In this study, low-cost software-defined GPS and SBAS Reflectometry (GPS&SBAS-R) systems have been built and proposed to measure ocean-surface wave parameters on board the research vessel New Ocean Researcher 1 (R/V NOR-1) and other ground-based coastal stations of Taiwan. A power-law ocean wave spectrum model has been used and applied with the Small Perturbation Method (SPM) approach to solve the electromagnetic wave scattering problem from rough ocean surface and compare with experimental seaborne GPS&SBAS-R observations. Meanwhile, the intensity scintillations of high-sampling GPS&SBAS-R signal acquisition data are thought to be caused by the moving rough surfaces of the targeted oceans. We found that each derived scintillation power spectrum is a Fresnel filtering result on sea/ocean-surface elevation fluctuations and depends on the First Fresnel Zone (FFZ) value and the ocean-surface wave velocity. The determined ocean-surface wave parameters, e.g. wave velocity and spectral index, have been compared and validated against nearby buoy measurements.
Development of Bayesian inverse modeling framework to verify CO2 emissions in Seoul
Authors: Sim Sojung , Jeong Sujong
Published: March 2024

The Bayesian inverse method, combined with measurements of atmospheric carbon dioxide (CO2) and a transport model, can serve as an independent verification approach to improve the precision of emission estimates. This study utilized the Bayesian inverse model, along with ground- and space-based measurements, to validate CO2 emissions in Seoul. A Bayesian inverse modeling framework was developed, integrating crucial input data such as anthropogenic CO2 emissions, biogenic CO2 fluxes, atmospheric CO2 measurements, a Lagrangian transport model, and error covariances for both prior emissions and observations. The averages of posterior emissions decreased after the inversion run, with a correction of approximately -8.69%. This suggests that the prior emissions were overestimated. There was an average 9.7% reduction in posterior emission uncertainties compared to prior uncertainties. The most substantial reductions in uncertainty were observed in areas with concentrated observation sites. The performance of the inverse model was thoroughly investigated through sensitivity analysis, encompassing different background representations, prior uncertainty levels, temporal and spatial uncertainties, and observational network configurations. Additionally, we quantified spatiotemporal changes in CO2 emissions due to COVID-19. The abundance of ground and space observations in Seoul provided robust constraints on urban CO2 emissions, allowing for an objective evaluation of the effectiveness of carbon reduction policies.This work was supported by Korea Environmental Industry & Technology Institute (KEITI) through "Project for developing an observation-based GHG emissions geospatial information map", funded by Korea Ministry of Environment(MOE)(RS-2023-00232066).
Estimating the Corotation Lag of the Plasmasphere Based on the Electric Field Measurements of the Van Allen Probes
Authors: Zhang Zhao , Liu Wenlong , Zhang Dianjun , Cao Jinbin
Published: March 2024

The corotation electric field driving the plasmasphere to corotate with the Earth body is important in establishing the topology of the inner magnetosphere and is usually calculated by assuming a 24 h corotation period. However, studies have found that a plasmasphere corotation lag exists, suggesting an overestimation of the electric field driving the plasmasphere to rotate with the planet in previous calculations. In this study, we use electric field measurements from the Van Allen Probes mission from 2012 to 2018 to obtain the distribution of the large-scale electric field in the inner magnetosphere. A new method is developed to extract plasmaspheric rotation information from electric field measurements. Our results show that the electric field driving the plasmaspheric rotation varies with magnetic activity, decreasing with increasing Kp index. It is thus suggested that the corotation lag of the plasmasphere is more significant during magnetically active periods.
Substantial amounts of organic carbon are accumulated and stored in surface sediments of the Norwegian continental margin
Authors: Diesing Markus , Paradis Sarah , Jensen Henning , Thorsnes Terje , Bjarnadóttir Lilja , Knies Jochen
Published: March 2024

To keep the global average temperature rise well below 2°C requires drastic emission reductions and a removal of carbon dioxide (CO2) from the atmosphere. It has been suggested that part of the CO2 removal could be achieved by nature itself, if ecosystems that remove substantial amounts of carbon from the atmosphere are protected, managed, or restored. In the marine environment, the focus has so far been placed on coastal ecosystems with rooted vegetation (saltmarshes, mangroves, and seagrass beds), as they sequester carbon at high rates, are threatened by human activities and are amenable to management. Collectively, these are called actionable Blue Carbon ecosystems. More recently, other ecosystems such as marine sediments have been put forward, but these are currently considered emerging Blue Carbon ecosystems, as knowledge gaps do not allow us to decide yet, whether they are actionable or not. To help close some of the existing knowledge gaps we applied machine learning to spatially predict the amount of organic carbon that is stored in sediments of the Norwegian continental margin and the rates at which it is accumulated. We found that Norway has 100 times more organic carbon stored in its surficial (0 – 0.1 m sediment depth) seabed sediments than in its vegetated coastal ecosystems (0 – 1 m sediment depth). Rates of organic carbon accumulation vary spatially and are highest in depressions of the continental shelf that were carved out by glaciers during the last ice age. These so-called glacial troughs are found on the formerly glaciated continental margins of North America, Eurasia, south America, and Antarctica, covering an area ten times larger than that we mapped and might be important places of organic carbon accumulation globally. To improve our estimates of how much carbon accumulates in marine sediments at a global scale will require a) data on organic carbon content, dry bulk density and sediment accumulation rates of sufficient quality and quantity, b) relevant predictor variables of global coverage and sufficient resolution, and c) predictive spatial models that consider the complex nature of continental margins, where centres of organic carbon accumulation and cycling might be found in close proximity to each other. Based on improved global estimates of organic carbon stocks, accumulation rates and the release of CO2 due to anthropogenic disturbance (demersal fisheries, seafloor cables, offshore wind farms, deep-sea mining etc.) it should be possible to decide whether marine sediments can be considered actionable Blue Carbon ecosystems.
Quality control for multi-GNSS uncombined PPP ambiguity resolution using a sequential Kalman filter
Authors: Cao Xinyun , Soja Benedikt
Published: March 2024

To achieve highest precision in positioning and navigation, frequency transfer, ionosphere monitoring, etc. with global navigation satellite system (GNSS) data, the technique of uncombined precise point positioning (PPP) ambiguity resolution holds great potential. Unified data processing and reliable ambiguity resolution for multi-GNSS are essential prerequisites. Consequently, we propose a refined approach for quality control of multi-GNSS uncombined PPP ambiguity resolution employing a sequential Kalman filter. In addition to addressing the implementation of uncombined PPP ambiguity resolution, our focus extends to the selection of the reliable ambiguity datum, computational efficiency and refining the ambiguity resolution strategy. When quad-constellation GNSS data are processed, the results demonstrate that employing the sequential Kalman filter with OpenMP can enhance computational efficiency by approximately three times compared to the standard filter. Additionally, the sequential Kalman filter is also convenient to incorporate the ambiguity datum or the fixed ambiguity as a strong constraint and complete the post-residuals check for further validating the ambiguity resolution. Following the consideration of a set of indicators, e.g., arc length, cutoff angle, ratio value and success rate, for controlling reliable ambiguity resolution, the incorrect ambiguity fixing rate can be effectively reduced, especially during the convergence stage.
Revealing the role of Nature-based Solutions as drought adaptation strategies
Authors: Bertini Claudia , Ali Muhammad Haris , Jonoski Andreja , Popescu Ioana , van Andel Schalk Jan
Published: March 2024

Climate change has caused an increase in the frequency of hydrometeorological extremes world-wide, opening new challenges for decision makers and stakeholders in managing and regulating water. Among the adaptation strategies available, Nature-based Solutions (NBSs) gained increasing attention in recent years, because of their efficiency in reducing hydrometeorological risks while also providing additional benefits for biodiversity, landscape and society. Despite the ever-increasing interest for NBSs, many stakeholders still doubt their potential, as the quantitative effects of NBSs over long periods of time are still to be assessed.In this research, we show how several types of NBSs, such as wetlands restoration, infiltration ponds, ditch blocking and others, can be used to adapt to drought conditions under the future climate projections. We use as a pilot case the transboundary Aa of Weerijs catchment, shared between Belgium and the Netherlands, which recently became drought-prone. We develop a fully distributed coupled MIKE SHE-MIKE 11 model to mimic the hydrological behaviour of the catchment in present (2010-2019) and future climate conditions (2050-2059, scenario KNMI ‘23). The same hydrological model is then used to test the effectiveness of different drought adaptation measures, based on single type or combinations of NBSs. To quantify the impacts of the chosen strategies to adapt to drought conditions and in consultation with some local stakeholders, we define a set of Key Performance Indicators (KPIs) that provide tangible results for stakeholders and decision makers. Finally, we show the results of the different adaptation strategies implemented on a web-app, which can be accessed and used by decision makers and stakeholders as an aid tool to select the best adaption strategy.This research has been developed within the project EIFFEL (Revealing the role of GEOSS as the default digital portal for building climate change adaptation and mitigation applications, https://www.eiffel4climate.eu/), funded by European Union’s Horizon 2020 research and innovation programme under Grant Agreement Νο 101003518.
Policy implications to encourage the adoption of Nature-based Solutions in Vietnamese Mekong Delta (VMD).
Authors: Banerjee Sreejita , Ho Loc Huu , Pal Indrajit
Published: March 2024

Deltas are often densely populated and support much of the world’s fishes, forest products and agriculture. Protecting livelihoods and ecosystem services in deltas is therefore of global importance. The environmental degradation and the climate change are one of the multiple pressures experienced by deltas affecting the ecosystem services that pose risk in the livelihoods of the locals as well as the global population living in these areas. There is a need for new strategies for sustainable development to help deltas mitigate the effects of climate change as well as adapt to the changing conditions in a context of increasing uncertainty of hazards. Coastal areas of the Vietnamese Mekong Delta (VMD) are highly vulnerable due to land use changes and extreme climate hazards. This study will explore the specific aspects of deltas from a complexity-based approach, and analyse Nature-based Solutions as alternatives towards sustainable development in these areas. This examines Nature-based solutions (NbS) as a complementary or alternative approach to managing hazards in the Vietnamese Mekong Delta. We investigated the potential NbS as a complementary and sustainable method for mitigating the impacts of coastal disaster risks, mainly cyclones and floods. Finally, we address this gap by conducting a systematic literature review to assess the existence of policy instruments such as the Law on Natural Disaster Prevention and Mitigation (2009), Flood and Storm Prevention and Control (2000), Law on Dykes (2006), that adopt NbS and to evaluate the existence of specific examples of NbS.
Sensitivity of salt intrusion in estuarine networks to geometry using an idealised model 
Authors: Biemond Bouke , de Swart Huib E. , Dijkstra Henk A.
Published: March 2024

 Salt intrusion in estuaries threatens freshwater availability and agriculture in coastal regions. The geometries of most estuaries are heavily anthropogenically modified, for instance for shipping, land reclamation and flood protection. The response of the salt intrusion to modifications of the geometry is thoroughly studied for single channel estuaries. However, a significant fraction of earths estuaries consists of a network of channels, in which the dynamics are more complex, because it includes the distribution of water and salt at branching points. We aim to identify, quantify, and understand the differences in response to changes in the geometry occurring in estuarine networks compared to salt intrusion in single channel estuaries. To achieve this, we have developed an idealized width-averaged model, which solves for hydrodynamics and salt intrusion in an estuarine network. The advantages of this model are that it is flexible in its geometry and has a short runtime. The Rhine-Meuse Delta (the Netherlands) is taken as a reference case. A set of simulations using different geometries is performed with the calibrated model. An example of a result which we obtained is that channel deepening increases salt intrusion locally, but decreases salt intrusion elsewhere in the channel network. These results give insights in the vulnerability of salt intrusion in estuarine channel networks.
Molecular characterization of the formation and aging of biomass burning-derived organic aerosols
Authors: Carstens Cecilie , Bell David , Sari Doré Félix , Zgheib Imad , Top Jens , Dubois Clément , Zhang Yanjun , Dignum Juliette , Lynch Carys , Le Chen , Perrier Sébastien , Cazaunau Mathieu , El Haddad Imad , De Haan David , Picquet-Varrault Bénédicte , Riva Matthieu
Published: March 2024

Secondary organic aerosols (SOA) have significant effects on visibility1, human health2, and climate3. They are formed from the oxidation of volatile organic compounds (VOCs) in the atmosphere, leading to less volatile oxidation products that can subsequently partition into, or react with existing, aerosol particles.4-5 Biomass burning (BB) is estimated to be the second-largest source of VOCs and the largest source of fine OA globally.6 Extreme fires have been estimated to increase by 30% by 2050, which will greatly increase the concentration of BB VOCs and OA in the atmosphere. While photochemistry and humidity are known to influence SOA formation and aging,7–10 their impacts on BB-SOA remain poorly constrained and should be addressed to better capture the evolution of BB-SOA in the atmosphere.In this work, an oxygenated aromatic BB-marker, i.e., o-cresol (C7H8O), and two types of fuels (South African grass and chaparral from California) were used to study the chemical processes leading to the formation and aging of BB-SOA. The experiments were conducted in simulation chambers at PSI and LISA, respectively. Various oxidants (OH, O3, NO3) and humidity levels were used for these experiments, to explore gas- and particle-oxidation processes. A fast-switching chemical-ionization Orbitrap mass spectrometer, and a Vocus proton-transfer-reaction mass spectrometer were used to characterize gaseous species, while BB-SOA were characterized using an extractive electrospray ionization mass spectrometer, and a newly developed Vocus wall-less aerosol load - evaporator (WALL-E) AIM mass spectrometer. 1 Finlayson-Pitts, B. J. et al. Chemistry of the upper and lower atmosphere: theory, experiments, and applications; Academic Press: San Diego, 2000.2 Nel, A. Science 2005, 308, 804–805.3 Boucher, O. et al. IPCC Report 2013, 571–657.4 Ziemann, P. J. et al. Chem. Soc. Rev. 2012, 41, 6582.5 Srivastava, D. et al. NPJ Clim. Atmos. Sci. 2022, 5, 22.6Akagi, S. K. et al. Atmos. Chem. Phys. 2011, 11, 4039–4072.7 McNeill, V. F. Environ. Sci. & Technol. 2015, 49, 1237–1244.8 Xu, W. et al. Environ. Sci. & Technol. 2017, 51, 762–7709 Kuang, Y. et al. Environ. Sci. & Technol. 2020, 54, 3849–3860.10 Wang, J. et al. Proc. Natl. Acad. Sci. (PNAS), 2021, 118.
Role of lithosphere and mantle composition on tectonic and magmatic variability of oceanic accretion at slow spreading ridges
Authors: Rajeevan Remisha , Maia Marcia , Rospabé Mathieu , Olive Jean Arthur , Pelleter Ewan
Published: March 2024

The Mid-Atlantic Ridge (MAR) is a complex system comprising spreading centers, transform faults and associated volcanic features, and it is divided into distinctive accretionary segments by axial discontinuities (Sempere et al., 1990). Our focus is on two specific sections of the MAR recently surveyed during several cruises, the central MAR and the equatorial MAR. Our aim is to investigate the complex interplay between tectonics, volcanism and hydrothermal processes in the building of the axial lithosphere.At present, our investigation focuses on the central Mid-Atlantic Ridge (24° N to 24°40’ N), surveyed by the HERMINE 1 & 2 cruises. This area is characterized by extensive faulting demonstrating a broad spectrum of lengths and thrust magnitudes. The fault lengths vary from tens of meters to several kilometers, while thrust ranges from a few meters to 1.2 kilometers. The volcanic characteristics in this area encompass narrow, axis-parallel ridges emplaced on the rift valley floor as well as a range of volcanic features, from minor cones to substantial volcanoes.The rift valley comprises a sequence of intermittent deep basins featuring minor linear topographic elevations on the valley floor associated with recent volcanism, suggestive of recent dike emplacement. The terrain is notably uneven, particularly in the northern section, where talus accumulates adjacent to a large normal fault of 9.2 kilometers long with a vertical offset of 930 meters, located at the segment end, possibly a detachment fault. Volcanic summits are present near this fault, suggesting a potential failed detachment. The spreading axis exhibits a slight clockwise rotation at 24°30’ N. Samples collected during the HERMINE 1 and 2 cruises through dredging and dive methods include various rock types such as basalts, gabbros and serpentinized/mineralized peridotites. The presence of serpentinized/mineralized peridotites provides clues about hydrothermal circulation and exhuming mantle rocks to the seafloor.By addressing a joint study of the bathymetry and the sample petrology, we will study the evolution of this portion of the ridge axis in connection with tectonic, magmatic, and hydrothermal processes.
PRODEM: An annual series of summer DEMs (2019-2023) for the marginal areas of the Greenland Ice Sheet
Authors: Winstrup Mai , Ranndal Heidi , Larsen Signe H. , Simonsen Sebastian B. , Mankoff Kenneth D. , Fausto Robert S. , Sørensen Louise S.
Published: March 2024

Surface topography within the marginal zone of the Greenland Ice Sheet continually evolves in response to varying weather, season, climate and ice dynamics. However, existing ice sheet Digital Elevation Models (DEMs) usually rely on multi-year data, obscuring these changes over time. We have here developed an annual series (2019-2023) of summer DEMs in 500m resolution for the Greenland ice sheet marginal zone, referred to as PRODEMs. Encompassing all outlet glaciers from the Greenland ice sheet, these PRODEMs result from fusing CryoSat-2 radar altimetry and ICESat-2 laser altimetry using a regionally-varying Kriging method. Validated through leave-one-out cross-validation, they demonstrate accurate representation of surface elevations within the spatially varying prediction uncertainties with a median value of 1.4m.The PRODEMs capture the recent annual evolution in summer surface topography of all outlet glaciers from the Greenland ice sheet. We observe a general lowering of surface elevations compared to ArcticDEM, but the spatial pattern of change is highly complex and with annual changes superimposed. The PRODEMs offer detailed insights into marginal ice sheet elevation changes, temporally as well as spatially, making them valuable for researchers and users studying ice sheet dynamics under changing environmental conditions.
Assessing the Influence of Climate Forcing Data Resolution on Simulations of Glacier and Freshwater Dynamics for the Flade Isblink Ice Cap, Northeast Greenland
Authors: Shafeeque Muhammad , Vlug Anouk , Marzeion Ben
Published: March 2024

High-resolution climate data is crucial for accurate glacier modeling in topographically complex regions. This study investigates the necessity of such data for accurate simulations of glacier and freshwater dynamics for the Flade Isblink Ice Cap (FIIC), Northeast (NE) Greenland. It also explores the potential of achieving comparable results using coarse-resolution global datasets with region-specific scaling.The study employed an advanced subdivision of FIIC, consisting of 299 glaciers, including six active marine-terminating ones. Four climate datasets (ERA5, CRU, W5E5, and ERA-Interim dynamically downscaled using polar WRF for NE Greenland) with 5-50 km spatial resolutions were used to force the Open Global Glacier Model (OGGM) from 2014 to 2018. OGGM was calibrated glacier-by-glacier against high-resolution geodetic-altimetric mass balance, frontal ablation, and volume data. Sensitivity analyses were conducted with and without regional scaling for all selected climate datasets and calibration parameters.The high-resolution WRF dataset provided an accurate initial regional volume estimate (with a minimal deviation of -0.6 % from the reference) without any local corrections, while other datasets underestimated volume, increasing with decreasing resolution from 8 % to 15 %. However, applying regional temperature bias and precipitation factor significantly improved the accuracy of these estimates, reducing the underestimation from just 2.1 % to 2.4 %. Sensitivity analysis revealed that the precipitation factor has a moderate influence, while temperature bias has a higher influence on the modeled volume. Without scaling, coarse datasets underestimated annual freshwater runoff by 25 % to 34 %, but with regional scaling, this discrepancy was markedly reduced to a near alignment with the WRF dataset at 0.5 % to 1.6 %, corresponding to 9.8 Gt/yr. Across datasets, summer months (June, July, August) runoff estimates showed no significant differences (p>0.05) after regional scaling.The study concludes that high-resolution climate data enhances the accuracy of initial volume estimates, thereby increasing confidence in simulated results. However, appropriate local adjustments to coarser datasets can yield comparable glacier and freshwater runoff simulations. Initial volume estimates are crucial for future projections. Future modeling efforts will explore the sensitivities of regional scaling and parametrization on improving projections of freshwater contributions into the ocean and their feedback on glacier-ocean interactions.
Impact of Chaotic Advection on Solute Transport in Porous Media
Authors: Feistner Carla , Basilio Hazas Mónica , Wohlmuth Barbara , Chiogna Gabriele
Published: March 2024

Chaotic advection can enhance mixing processes in porous media by increasing the solution-solvent interface available for diffusion. While the pore structure can generate chaotic advection at the pore scale, transient flow fields can lead to chaotic advection at the Darcy scale. This concept can be applied to groundwater remediation, as the flow field can be engineered using injection-extraction systems. This study investigates two injection-extraction systems known to exhibit chaotic structures: a source-sink dipole and a rotated potential mixing. Using Lagrangian particle tracking combined with random walk we solve the stochastic differential equation to simulate solute transport. The pulsed source-sink system is parametrized by the pumping rate, while for the rotated potential mixing system, we use the rotation angle and the rotation frequency to change the flow properties. Using a grid search over the parameter spaces of both systems, we test different configurations. We quantify the temporal increase in dilution and the mixing enhancement with the dilution index by using a novel approach of selecting the optimal grid size with minimal approximation error for each particle density estimation. Furthermore, we analyze the corresponding flow structure to identify Kolmogorov-Arnol'd-Moser (KAM) islands, non-mixing regions that arise around elliptic points of the flow. We find that the parameters of the system control the occurrence and size of KAM islands, which consequently affect the increase in dilution by limiting the chaotic area in the domain. Overall, our results show that not all chaotic systems lead to the same maximum mixing enhancement. Therefore, it is important to properly assess the uncertainty in the design parameters of injection-extraction systems to effectively engineer chaotic advection.