bluuebunny/crossref_metadata_2025 huggingface dataset:
Atmospheric boundary layer structure at a small Alpine valley head detected with a network of UAS and ground-based sensors
Authors: Alexa Almut , Wildmann Norman , Gohm Alexander
Published: March 2024

In mountainous areas, the transport and exchange of mass, energy, and momentum in the atmospheric boundary layer (ABL) happens not only in the vertical, but also in the horizontal, and on multiple scales. The associated processes will be investigated within the observational campaign (TOC) of the TEAMx program at various locations. In a pre-campaign in 2022 (TEAMx-PC22), several sites, instrumentation, and measurement strategies were tested.A site called Nafingalm was identified as a potential location for the investigation of boundary layer processes in a small Alpine valley. The site is located at the head of a tributary valley to the Inn Valley in Tyrol, Austria.Measuring all the relevant scales within the ABL in the valley requires distributed sensors at the ground, but also aloft, ideally up to the boundary layer height. For this purpose, simultaneous, distributed measurements were conducted with quadrotor UAS from the SWUF-3D fleet during the TEAMx-PC22. Different configurations and flight strategies were tested between 20th and 28th June 2022 with up to three UAS being operated at the same time. The main flight strategies were simultaneous vertical profiles along the valley up to 120 m above ground, and horizontal profiles across the valley at up to 40 m above ground. Additionally, ground-based instrumentation was deployed during a three-month period to get a better understanding and statistics of typical conditions in the valley.A case study was done for 23rd June 2022, analyzing the atmospheric processes that occurred during different periods of the day. It could be concluded that the UAS measurements were an important addition to and extension of the ground-based measurements. They illustrated the occurrence of thermally-driven winds, foehn winds, and the formation of a stable boundary layer at the valley ground. Nafingalm proved to be a suitable location to observe local and mesoscale phenomena and their interaction.
Where does the AMOC peak? Assesssing regional variations in North Atlantic Overturning from GLORYS12 
Authors: Katsman Caroline , Oldenhuis David , Vermeulen Dennis , Gelderloos Renske
Published: March 2024

The Atlantic Meridional Overturning Circulation (AMOC) transports vast amounts of heat to high latitudes, and is largely responsible for Western Europe’s relatively mild climate. Climate models project the AMOC will weaken substantially over the 21st century, which impacts weather, climate, sea level and the oceanic carbon cycle. In many studies, the AMOC state is described in a condensed two-dimensional view or even by means of a single metric, which leaves many aspects of its complex 3D-structure underexposed. By revealing the sharp contrast in overturning strength between the western and eastern subpolar gyre (SPG), the recent OSNAP observations emphasized the importance of considering the AMOC in 3D.In this study, we explore this further by analyzing the characteristics of the overturning in density space in the North Atlantic SPG on a regional scale, and over time periods ranging from seasons to decades. For this, we use model data from the high-resolution GLORYS12 reanalysis, spanning the period 1993-2020. Following the approach applied in OSNAP, the overturning is assessed from alongstream changes in boundary current transport in specific density classes. This analysis is performed for the entire SPG, for its major basins (Iceland Basin, Irminger Sea, and Labrador Sea) and for smaller segments along the boundary currents, thus providing detailed insights in variations of the overturning varies along the entire SPG boundary.The mean overturning from GLORYS12 for 1993-2020 is 23.8 Sv, distributed as 41%, 29%, and 30% for the Iceland Basin, Irminger Sea, and Labrador Sea respectively, and peaking at increasingly higher densities in alongstream direction. Within each basin, a pronounced seasonal cycle can be identified, with the maximum overturning occurring in March and the minimum in September. Over the entire reanalysis period, the overturning strength in both the Iceland Basin and Irminger Sea exhibits a weak decreasing trend, whereas the Labrador Sea displays a weak increasing trend. The subdivision in shorter segments reveals large spatial differences in overturning, both with regard to its overall strength and its distribution over density classes. However, these outcomes are less robust than the analyses on the scale of the major basins, as the flow is highly variable and numerical uncertainties associated with offline overturning calculations become more prominent.Further research is needed to properly interpret these regional variations, and thereby improve our understanding of the AMOC dynamics and its sensitivity to changing oceanic and atmospheric forcing conditions. Linking them to local processes known to govern the overturning (i.e., formation of dense waters in the interior of marginal seas and their export, formation of dense waters within the boundary current system itself and the exchange of waters via overflows) seems a viable route.
Review and analysis of atrazine adsorption on different microplastics in aqueous solution. 
Authors: Biswas Bishwatma , Goel Sudha
Published: March 2024

Microplastics (MPs) are ubiquitous in all kinds of water matrices. The different properties of MPs facilitate their role as carriers of emerging contaminants like pesticides, pharmaceuticals, PFAS and surfactants. Hydrophobic pesticides have a high tendency to be adsorbed on non-polar substances such as MPs. The widespread use of atrazine has caused it to be omnipresent in the environment, leading to their concurrent presence with MPs. The partitioning and fate of atrazine sorbed MPs are governed by various environmental conditions and physicochemical characteristics of different matrices. The interaction of MPs with pesticides enables MPs to serve as vectors for the transport of pesticides in aquatic media. In this work, the sorption of atrazine on polyethylene MPs was investigated in batch adsorption studies. The characterization of MPs was conducted using FTIR, SEM and XRD. By examining the characteristics of MPs and atrazine, an adsorption mechanism is proposed. The sorption of atrazine on PS was mainly governed by van der Waals forces and pore-filling mechanism. The effect of contact time on the adsorption of ATZ on PS was examined. Contact time was used to compare the results of different experiments as it is necessary to establish an equilibrium time that can be used in all the experiments. It was found that the pseudo-second order model was a better fit than pseudo first order-model based on the highest R2 values obtained. Finally, the effects of salinity and pH were also measured and found to be relatively limited. The results of this study prove that MPs can act as carriers of pesticides like atrazine in aqueous medium.
The Cyprus Atmospheric Observatory: A unique outpost to monitor the increase of Middle East Air Pollution 
Authors: Bimenyimana Elie , Pikridas Michael , Oikonomou Konstantina , Iakovides Minas , Vasiliadou Emily , Savvides Chrysanthos , Mihalopoulos Nikos , Sciare Jean
Published: March 2024

Cyprus is located at the south easternmost of the Mediterranean basin, a highly populated region (400 million inhabitants) threatened by exceptionally rapid urbanization and industrialization, intense dust storms, and heat extremes leading to drastic degradation of air quality, expected to exacerbate in the coming decades. Air pollution, especially particulate matter (PM), plays a crucial role in regional climate and has major adverse health effects and major economic consequences. The Cyprus Atmospheric Observatory (CAO) is a regional background station of the pan-European ACTRIS Research Infrastructure Network. It was established in 2015 with a view to fill-in the current observational gaps in this region through high quality, long term monitoring of atmospheric pollutants of climate and health relevance.
In close collaboration with the Department of Labour Inspection and in the framework of the Horizon 2020 EMME-CARE research project, CAO has built a unique and detailed PM chemical composition database for the past decade which was further processed to investigate the long-term trends using the mann-kendall non-parametric statistical test while the identification of the geographic location of the major pollution sources affecting the island was achieved through the Lagrangian particle dispersion model FLEXPART.
Based on the statistical Mann-Kendall trend analysis, an increasing trend in PM10 levels was observed at the regional background (CAO) station (+0.23 µg.m-3.y-1). It is interesting to note that the concentrations of most PM species are rising, especially mineral dust with an average increasing rate of +0.26 µg.m-3.y-1 followed by OM (+0.1 µg.m-3.y-1). The source regions analysis indicates that the Middle east sector is associated not only with the most elevated concentrations for the main PM10 components, both of natural (mineral dust) and anthropogenic origin (carbonaceous species, nitrate and nss-K+), but also with increasing trends for most of them. Especially for sulfate, it is worth mentioning that while rather stable levels were recorded for different source regions, the Middle East sector exhibited increasing trend (+0.2 µg.m-3.y-1) indicating increasing fossil fuel (oil and gas) emissions.
 
This project has received funding from the European Union’s Horizon 2020 EMME-CARE project (grant agreement No 856612).
 
The effect of the thermal properties of electrons on the dispersion of kinetic Alfvén waves
Authors: Sepúlveda Nicolás Francisco , Moya Pablo S. , López Rodrigo A. , Verscharen Daniel
Published: March 2024

The kinetic Alfvén wave (KAW) is an extension of the Alfvén mode to the kinetic scales that propagates at quasi-perpendicular angles with respect to the background magnetic field in a magnetized plasma. The KAW is characterized by a right-handed polarization in the plane orthogonal to the background magnetic field. This allows the KAW to resonate with electrons, as contrary to the electromagnetic ion-cyclotron (EMIC) wave, which resonates with positive ions due to it’s its left-handed polarization. The EMIC mode is also a kinetic extension of the classical Alfvén wave, and propagates at quasi-parallel wavenormal angles. Due to the relevance and overall presence of both of these modes in space plasmas, understanding the nature of the transition from the EMIC mode to the KAW is a matter of great interest for the study of the micro-scale physics of these systems.The transition from left-hand to right-hand polarized Alfvén waves depends on the wavenumber, plasma beta, temperature anisotropy, and ion composition of the plasma. Along with the temperature anisotropy, the electron-to-proton temperature ratio Te/Tp is of great relevance for the characterization of the thermal properties of a plasma. This ratio varies significantly between different space plasma environments. Thus, studying how variations on this ratio affect the polarization properties of electromagnetic waves becomes of high relevance highly relevantfor our understanding of the dynamics of space plasmas.In this work, we present an extensive study on the effect of the thermal properties of electrons on the behaviour and characteristics of Alfvénic waves in fully kinetic linear theory, as well as on the transition from EMIC to KAW. We show that the temperature ratio Te/Tp has strong and non-trivial effects on the polarization of the Alfvénic modes, especially at kinetic scales (k┴ρL>1, where k┴=k sinθ and ρL= cs/Ωp, with cs the plasma sound speed and Ωp the proton’s gyrofrequency) and βe+βp>0.5, where βs=8πnkTs/B2 is the ratio between thermal and magnetic pressure. We conclude that electron inertia plays an important role in the kinetic scale physics of the KAW in the warm plasma regime, and thus cannot be excluded in hybrid models for computer simulations.
Modelling the transport of microplastics in the Gironde estuary: Sensitivity to physical processes and their parameterizations
Authors: Kaimathuruthy Betty John , Jalon Rojas Isabel , Sous Damien
Published: March 2024

Studying microplastic transport in estuaries is challenging due to the dynamic interplay between river and ocean, compounded by the diverse properties exhibited by these particles. Lagrangian particle-tracking numerical modelling is a relevant tool for investigating microplastic transport dynamics, dispersion patterns, and vertical distribution. However, these models oversimplify the parametrizations of crucial estuarine processes by ignoring the effect of varying water density or vertical diffusion coefficients. In this study, we implement a hydrodynamic and improved particle tracking model in the macrotidal Gironde estuary (SW France) to explore the relative importance of different physical processes (time-space varying vertical diffusivity and water density, beaching-refloating, bottom resuspension) and provide a better understanding of microplastic dispersion and potential trapping. The simulated particle trajectories and density distributions from our findings indicate a limited influence of the spatio-temporal variability of vertical turbulence on floating particles, with a notable impact observed for settling particles, showing its significance in particle resuspension. Despite the time-space-varying water density, the effect on the transport patterns of both floating and settling microplastics is relatively lower, while the phenomenon of beaching-refloating increases the particle's residence time within the upper estuary. The higher river discharge during the spring season flushes floating particles downstream, with a portion reaching the open sea, while settling particles persist within the estuary during both seasons. Notably, denser microplastic particles tend to accumulate in the upper estuary region during summer, where the estuarine turbidity maxima have been identified.
Unravelling succolarity to quantify multiscale petrophysical properties beyond porosity
Authors: Li Bo , Panaitescu Ciprian , Glover Paul , Wu Kejian , Lorinczi Piroska , Yu Bingsong
Published: March 2024

Characterising the complexity of spatial patterns and their underlying physics using a nonlinear approach is growing in many fields. Many features in geomaterials, such as pore and fracture systems, exhibit scaling behaviour, allowing their properties to be characterised using fractal theory.The widely used fractal dimension is a ratio that compares how the level of detail in a structure varies with its size, measuring its space-filling ability. Lacunarity, derived from the Latin word "lacuna," meaning "gap," quantifies the “voidness” of a texture. Nevertheless, neither fractal dimension nor lacunarity can characterise the percolating properties of a fractal. Mandelbrot coined the concept of succolarity. Given that "percolare" in Latin translates to "to flow through," the term "succolare" (sub-colare) aptly conveys the concept of "to nearly flow through" in neo-Latin. A succolating fractal is characterised by almost containing the connecting paths that permit percolation, i.e., one below the percolation threshold. However, it remains a less known notion than the other two fractal counterparts. In the last ten years, succolarity has evolved from an idea to a computable parameter. It has characterised many patterns in different scales and fields, such as medical objects, material surfaces, and networks from nano-micropores to rivers.In this contribution, we aim (i) to understand the physical meaning of succolarity and how it relates to pore networks and other petrophysical properties across different scales, and (ii) to provide new approaches to succolarity calculation. We implemented the succolarity algorithm using the gliding box-counting method. We then re-examined the published datasets for validation and comparison. The succolarity for 2/3D images of rock samples and synthetic models with various porous structures was also calculated for deeper understanding. Finally, we correlated the succolarity results with porosity, permeability, and other petrophysical parameters.Our findings reveal that (i) succolarity contains information about a structure's anisotropy, phase fraction (e.g., porosity in the case of pore space), and percolation information. (ii) It is susceptible to connectedness. As we cut out smaller pores of a structure, succolarity decreases linearly until a pore size (porosity) threshold is reached; it drops significantly and follows a power law. (iii) Succolarity (Su) and permeability are fitted to an exponential relation: k = aebSu. The computation of succolarity excludes isolated pores for a given flooding direction, allowing it to reflect the flow properties better than porosity alone. (iv) Moreover, it is worth noting that using pressure or velocity field in the succolarity calculation algorithm would endow it with a clearer physical meaning than being a proxy for porosity.
Methane Cycling Communities in Arctic coastal and submarine permafrost environments 
Authors: Anthony Sara E. , Yang Sizhong , Knoblauch Christian , Kallmeyer Jens , Jenrich Maren , Strauss Jens , Liebner Susanne
Published: March 2024

Thermokarst lagoons form at the terrestrial-marine interface when thermokarst lakes, hotspots for Arctic methane emissions, erode into the ocean. These lagoons are dynamic environments with seasonal ice build-up and potential alternations between freshwater and marine discharge and make an excellent natural laboratory for studying methane cycling communities as they shift from a terrestrial to marine environment. Our study site encompassed two thermokarst lakes and one thermokarst lagoon on the Bykovsky Peninsula in NE Siberia. In-situ methane concentrations, methane-carbon isotopic signatures, analysis of amplicon sequencing variants (ASVs), metagenomics, and pore-water geochemistry point towards efficient communities of anaerobic methane oxidizers (AOM) in a sulfate-methane transition zone 2-3 meters below the sediment surface of the lagoon. The methanogenic community in the sediment was dominated by methylotrophic methanogens. This is potentially the first known example of dominance of these often-ignored methanogens in a terrestrial/semi-terrestrial environment. Further molecular analyses also revealed an unusual co-occurrence of terrestrial/freshwater ANMEs, specifically of Candidatus Methanoperedens, with typical marine ANME2 a/b in the sulfate-methane transition zones of both systems. Our studies suggest that AOM can locally efficiently reduce sediment methane concentrations of subaquatic permafrost environments, especially of those with marine influence.
 Power-spectra of turbulent buoyant jets from laboratory measurements
Authors: Gkoutis Konstantinos , Papakonstantis Ilias , Papanicolaou Panagiotis , Dimitriadis Panayiotis
Published: March 2024

In total, 11 experiments of turbulent buoyant jets were carried out in an experimental apparatus, which includes a tank with dimensions 1.00 m x 0.80 m x 0.70 m. Specifically, in a stationary homogeneous ambient fluid, six (6) experiments were performed, with a temperature at the outlet significantly higher than the ambient water, and five (5) experiments with the same temperature but in an ambient saltwater environment of initial density difference between 18.4 and 19.2 kg/m3. The nozzle diameter was equal to 1.5 cm in all experiments, the densimetric Froude number was ranging between 1.72 and 3.73, and the Reynolds number ranging between 1222 and 3136. The experiments included flow visualization and concentration measurements based on the Laser Induced Fluorescence (LIF) technique using Rhodamine 6G as fluorescent tracer. A planar laser sheet was created and the experiments were recorded using a suitable video camera. The energy-spectra of the concentration were estimated using Fast Fourier Transformation and were compared to theoretical arguments, such as the K41 model.
Propagation of meteorological to streamflow flash droughts during summer monsoon season in India
Authors: Singh Rajesh , Mishra Vimal
Published: March 2024

Streamflow flash droughts (SFDs), characterized by a rapid decline in streamflow over a relatively short period, affect water availability, hydropower generation, and the ecosystem. However, the atmospheric and land processes that drive SFDs in the monsoonal climate of India remain unexplored. Using observations, reanalysis datasets, and model simulations, we examined the critical drivers of SFDs in 64 catchments in India during the 1971-2018 period. We identified meteorological flash droughts (MFDs) using precipitation and SFDs using in-situ observations and model simulations of streamflow. We show that precipitation deficit and anomalous high temperatures, driven mainly by summer monsoon breaks, lead to the development of MFDs. Antecedent baseflow conditions play a major role in the propagation of MFDs to SFDs. Favourable atmospheric conditions (driven by monsoon breaks) cause meteorological flash droughts, which translate to streamflow flash droughts. High and low baseflow conditions limit the rapid decline in streamflow, which controls the occurrence of streamflow flash drought. On the other hand, favourable atmospheric conditions combined with moderate baseflow can trigger streamflow flash droughts in India during the summer monsoon season. Moreover, humid catchments are more prone to propagation from meteorological to streamflow flash droughts during the monsoon season in India. Understanding the crucial role of atmospheric and land drivers can assist in examining the occurrence of streamflow flash drought with implications for water resources planning and management. 
Corporate Communication on Voluntary Carbon Offsetting in the Aviation Industry: A Case Study of Asian Airlines
Authors: Tsoi Heung Ng
Published: March 2024

The aviation industry, among the transportation sector, has come under heightened scrutiny as it is a major contributor to global carbon emissions and one of the most challenging industries to decarbonize. In response to the overwhelming calls for climate actions, the aviation industry has turned to a market-based approach - voluntary carbon offsetting - showcasing their dedication to carbon reduction. Investing in high-quality carbon offset projects holds great significance and contributes to the global efforts aimed at reducing carbon emissions. However, the corporate communication of airlines, crucial in influencing public perception and comprehension regarding voluntary carbon offsetting, has faced criticism for its lack of transparency and accuracy. This research therefore investigates the communication practices of voluntary carbon offsetting in the aviation industry, focusing on accessibility, clarity and transparency, and operational aspects. The study employs a multi-faceted approach, including a literature review on greenwashing, a case study of five Asian-based airlines, and the development of a coding scheme for content analysis. By examining the airlines’ official websites and sustainability reports, we seek to identify patterns and variations in their communication strategies on voluntary carbon offsetting. Preliminary results from the literature review and ongoing case study analysis showcase the importance of accessibility, transparency, and clarity in voluntary carbon offsetting communication. As the research progresses, further content analysis will unveil the potential instances of misleading tactics and highlights of best practices, fostering a more informed and transparent approach to voluntary carbon offsetting communication in the aviation industry. 
Analysis of long time series of space-geodetic techniques at co-location sites to identify technique- and instrument-specific systematics
Authors: Kehm Alexander , Seitz Manuela , Glaser Susanne
Published: March 2024

Highly accurate Terrestrial Reference Frames (TRF) – based on the combination of the four space-geodetic techniques Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI), Global Navigation Satellite Systems (GNSS) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) – are the fundamental backbone for a broad range of applications like land surveying, the geodetic monitoring of geophysical processes within the Earth system or navigation on and near the Earth’s surface. Recent efforts at the Geodetic Observatory Wettzell (GOW), Germany, aim at a transition from the purely geometric link between space-geodetic techniques via local ties as the current standard to an innovative quasi-error-free combination based on a common clock (CC) and a common target (CT).Once the CC/CT-based infrastructure at GOW is fully developed and operational, it will be possible to uncover systematics between the space-geodetic techniques as well as individual instruments. However, to guarantee the long-term accuracy and stability of the TRF, it is indispensable to know and, if possible, to eliminate the systematics over the entire observation period of the techniques. A prerequisite for this is to compile an inventory of the existing discrepancies between the techniques and their possible causes.The DFG research unit ‘Clock Metrology: Time as a New Variable in Geodesy’ features a joint project by DGFI-TUM and Uni Bonn with focus on developing a new CC-/CT-based approach to combine the space-geodetic techniques. As a basis, we develop an approach to analyse and cross-compare station position time series from different instruments/techniques observed over several decades. Based on the example of GOW co-locating all four space-geodetic techniques, we investigate absolute station position time series consistently aligned to the datum of the DTRF2020, DGFI-TUM’s most-recent realisation of the International Terrestrial Reference System (ITRS), as well as differential time series eliminating datum-realisation-related variations in the time series of one technique. Finally, we prepare a pool of metadata (log files, data time series from meteorological sensors and weather models, estimated clock and tropospheric parameters, etc.) and include these data in the analysis to identify causes of systematics. From the analyses, discontinuities, time-variable drifts and the spectra of intra- and inter-technique position difference time series between individual instruments at GOW can be identified and interpreted. The result of the work is an inventory which lists both, known and previously unmodelled systematics, and, as far as possible, their causes, thus providing the basis for the consistent combination of techniques in a common space-time.
Recent Advances in Earthquake Monitoring in Madagascar
Authors: Rakotoarisoa Andriniaina Tahina , Razafindrakoto Hoby N. T.
Published: March 2024

Earthquakes are acknowledged as a potent force of nature that can cause substantial harm to populations and result in widespread damage. Therefore, having a seismic public alerting system is crucial for swiftly broadcasting warnings to the public and relevant risk agencies in the event of an earthquake. The system will send instantaneous notifications to users, allowing them to quickly implement protective measures for risk agencies, as well as offer feedback on individuals’ situations during the earthquake. In this regard, this study aims to build a wrapper for near-real-time earthquake monitoring. Our development includes four steps: (1) improvement of earthquake detection using PhaseNet (Zhu & Beroza, 2018) with PhasePApy (Chen & Holland, 2016) and the Rapid Earthquake Association and Location (REAL, Zhang et al., 2019) for picks association, (2) earthquake location refinement using the HYPOINVERSE program (Klein, 2002), (3) event classification with the CNN classification method, and (4) rapid earthquake notification through email and a locally designed application called SeismicBox2 for smartphones that include earthquake information and USGS shakemap. We conduct testing and validation of the system using earthquake data from Madagascar (archive and near-realtime)
Evidences for the influence from key chemical structures of per- and polyfluoroalkyl substances on their environmental behaviors
Authors: Yan Yulong , Zhuang Yiru , Wu Jing , Dong Bingqi , Wang Fan , Bo Yu , Peng Lin
Published: March 2024

In recent years, perfluoroalkyl and polyfluoroalkyl substances (PFASs) have received widespread attention from the international community due to their persistence, long range atmospheric transport (LRAT), bioaccumulation and toxic. This study carried out the atmospheric and precipitation observation in Beijing for nearly one year, and firstly simultaneously observed the pollution characteristics of ultra short-chain, short-chain, long-chain PFASs and their main isomers, focusing on their gas-particle partitioning mechanism and dry and wet deposition characteristics. The results showed that the total concentration of PFASs was 3,415±2,932 pg m-3, of which ultra short-chain PFASs accounted for the highest proportion (55%), followed by short chains (41%) and long chains (3.9%). The proportion of short-chain PFASs was greater than that of long-chain PFASs which may be because short-chains have been produced and consumed as substitutes for long-chain PFASs. After deducting PFASs in the aqueous phase of particulate matter, the gas-particle partitioning coefficients (-7.04 m3 μg to -5.49 m3 μg) were about 3–4 units smaller than the previous results (-2.77 m3 μg to -1.51 m3 μg), which could more accurately reflect the phase partitioning characteristics between the gas phase and the hydrophobic phase of particulate matter. All PFASs and their main isomers were more distributed in the gas phase, followed by the aqueous phase of particulate matter and the hydrophobic phase of particulate matter. Dry deposition was dominant in the atmospheric deposition of each PFAS and isomer, but the relative contribution of dry deposition was significantly different. It was found that the gas-particle partitioning coefficient can be influenced by key chemical structures such as carbon chain length, functional group type, and isomer structure. Furthermore, the gas-particle partitioning can influence the dry and wet deposition of PFASs. Specifically, PFASs with longer carbon chains, carboxylic acid functional group or branched chain structures had larger gas-particle partitioning coefficients and can be more distributed in the hydrophobic phase of particulate matter, and their relative contributions of dry deposition were smaller.
Impact of Saharan mineral dust layers on cloud formation and cloud properties
Authors: Gross Silke , Wirth Martin , Ewald Florian
Published: March 2024

Mineral dust contributes strongly to the global aerosol load. The largest source region of mineral dust is the Sahara. But mineral dust cannot be treated as a regional phenomenon. Once lifted in the air, it can be transported thousands of kilometers over several days. The main transport pathway spans over the Atlantic Ocean from Africa towards the Caribbean; with its peak season during the summer months. But transatlantic dust transport can also happen during wintertime, however with less frequency. In addition, the dust particles can be transported northward over the Mediterranean and Europe. In rare events, it can even reach the Arctic region. All the way during transport the dust layer has an impact on the Earth’s radiation budget, by direct interaction with the incoming and outgoing radiation by scattering and absorption, and by indirect interaction as dust can impact cloud formation and cloud properties.To study long-range transported Saharan dust as well as the dust’s impact on cloud formation and properties, airborne lidar measurements with the WALES lidar system onboard the German research aircraft HALO have been performed over the western sub-tropical North-Atlantic Ocean during NARVAL-II in August 2016 and EUREC4A in January/February 2020. We observed dust transport during the summertime in the clearly separated and well-defined Saharan Air Layer (SAL) as well as during wintertime, when dust transport happens at lower altitudes and the SAL is less separated. In addition, we were also able to capture an event of dust long-range transport into the Arctic during the HALO-(AC)3 campaign in spring 2022. From our measurements we could show, that small amount of water vapor embedded in the SAL has a strong impact on the atmospheric stability and thus also impacts the formation and properties of clouds during long-range transport. Additionally, dust particles are known to act as ice nuclei and with that lead to ice formation at different environmental conditions, changing the ice cloud’s microphysical properties.In our presentation we will give an overview of the performed WALES measurements. We use these measurements to study dust long-range transport and its impact on the atmospheric stability, cloud formation and cloud properties.
Exploring Macroalgal Carbon Dynamics in a Changing Climate of Arctic Fjords
Authors: Rabha Mayuri , Roy Biswajit , Singh Archana
Published: March 2024

The rapidly warming Arctic, exceeding global averages, experiences heightened macroalgal growth in high Arctic fjords due to rising seawater temperatures and reduced sea ice. However, uncertainties surround the consequences of climate-induced changes in the carbon cycle resulting from extensive macroalgal growth and increased carbon flux dynamics in these fjords. This study examines the fate of macroalgal-derived fatty acids (Saturated Fatty Acid: SFA, Monounsaturated Fatty Acids: MUFA and Polyunsaturated Fatty Acids: PUFA) across Kongsfjorden and Krossfjorden (Ny-Alesund) in response to Arctic amplification. For this study, dominant brown, green, and red macroalgal species (n=20), along with sediment samples (n=18) across the fjords, were collected during summer 2022. Brown algae dominated with the highest average fatty acid concentration 435.72 ±534.14 μg/g, while red and green algae had lower concentrations 72.84 ±52.75 μg/g and 90.25 ± 84.67 μg/g, respectively. Brown algae exhibited a concentration trend of SFA>MUFA>PUFA, while green and red showed SFA>PUFA>MUFA. The primary PUFA in these algae were n-C18 and n-C20, and filamentous growth forms exhibited higher levels compared to thallus or short/dwarf forms in green and red algae. However, brown algae, except for the genus Chorda, did not exhibit clear trends for these compounds. The distinct phylogenetic position of brown algae from red and green algae likely accounts for these divergent patterns. The filamentous form having the highest concentration of fatty acids could result from increased resistance to degradation, attributed to their minimized surface-to-volume ratio. Macroalgal species outside their natural habitat (ex-situ) had higher PUFA, MUFA, and SFA concentrations, likely due to unfavourable conditions of growth in intertidal regions, suggesting enhanced adaptation for growth across the arctic fjords. While in the sediments, a significant (~50%) reduction in the PUFA and MUFA fraction concerning SFA was observed. The transport of the algal material was more towards the outer fjord and was possibly favoured by glacial melting and runoff activities. The decrease in fatty acids derived from algae, coupled with the presence of iso- and anteiso- branched-chain fatty acids, implies limited residence and faster turnover of algal matter into intermediate metabolites by microorganisms, possibly bacteria. Such observation suggests a potential release of carbon fluxes into the atmosphere through degradation of lipids, and contributing to a negative trend in the macroalgal-induced carbon storage in fjords. 
Sub-Terahertz Inverse Synthetic Aperture Radar (ISAR) for monitoring of high-value space assets 
Authors: Alconcel Leah-Nani , Jones Gruffudd , Coe Morgan , Gashinova Marina , Cherniakov Mikhail
Published: March 2024

With the rise of commercial constellation implementation in low earth orbit (LEO), the near-Earth space environment is becoming increasingly challenging to monitor and protect. As well as carefully considered policy frameworks, new observational techniques and instrumentation are needed to ensure that safe operations can be maintained by all space users. The Pervasive Sensing group at the University of Birmingham is exploring in-orbit conditional monitoring of satellites using inverse synthetic aperture radar (ISAR) as a technique for dedicated observation of high-value space-based assets. Our previous concept and design results for fixed-beam dual freqency ISAR observations in circular orbits have been extended to a variety of scenarios. I will discuss some of our recent results from both experiments and simulation. 
The temporal evolution of long-range atmospheric microplastic deposition
Authors: Hagelskjær Oskar , Hagelskjær Frederik , Sonke Jeroen E. , Margenat Henar , Yakovenko Nadiia , Le Roux Gaël
Published: March 2024

This study investigated the concentration of microplastics (MPs) > 2 µm in multiple ombrotrophic sphagnum peat archives, providing a quantitative analysis of the temporal evolution of global atmospheric MP deposition. From the 1990s to 2020, deposition rates have increased from hundreds or thousands to tens or hundreds of thousands of MPs/m²/day, depending on location. Polyethylene (PE) dominated the composition of identified synthetic polymers, comprising 93.5% of identified MPs (Fig. 1). Notably, 95% of particles measured less than 20 µm in diameter, emphasizing the prevalence of small-sized MPs in atmospheric transport and deposition. Projections estimated a daily terrestrial deposition of 34±23 g of MP per square kilometer in 2023 depending on location, totaling 1.9 million tonnes/year globally. The exponential growth trend aligned closely with the annual plastic production rate and suggest a doubling of today’s MP deposition rate by 2030 (Fig. 2). Even in the improbable scenario of a complete cease in plastic production, atmospheric MP deposition rates are likely to increase in the coming decades due to the large amount of mobile legacy plastics in the environment.
Comparing and contrasting tracer dispersion at mesoscale and submesoscale
Authors: Thomas Jim
Published: March 2024

In this work we will compare and contrast the phenomenological changes in passive tracer dispersion at low and O(1) Rossby numbers using idealized flows. With increasing flow Rossby numbers, we find that the forward flux of tracer variance increases monotonically and the tracer variance spectrum shows severe depletion of the tracer field, indicating enhanced stirring of the tracer by higher Rossby number flows. On examining the physical structure of the tracer flux and its connection to strain and vorticity dominant regions in the flow, we find that a major share of the tracer flux is located in strain dominant regions between coherent vortices at low Rossby numbers, while at higher Rossby numbers the tracer flux is primarily located in vorticity dominant regions that are composed of fragmented bits of vorticity. The tracer field on the other hand is anticorrelated with the tracer flux, i.e. tracer variance is higher in physical regions where tracer flux is lower and vice versa. Our results highlight multiple anisotropic features of submesoscales that enhance tracer dispersion at O(1) Rossby numbers and emphasize the need to take into account the anisotropic features while developing parameterizations for large-scale ocean models.
Evaluating agricultural management systems: Case study of apple orchards in Chinese Luochuan
Authors: sun Weinan , zhang xiaoping , Gomez José Alfonso , Bai Gangshuan , An Zefeng , Liu Xuanhao
Published: March 2024

Agricultural management behavior is one of the core features of agricultural soil ecosystems. Poor human management may contribute to the rapid degradation of soils on a world-wide scale.Traditional management, which usually aims to maximize productivity, faces great challenges when pursuing agricultural soil health, high efficiency, and sustainable development. Evaluating the agricultural soil management system based on multiple perspectives is crucial for effectively guiding the management framework. A large number of research on agricultural management evaluation mainly focues on national and regional scales, and the evaluations are dominated by socio-economic indicators. Comprehensive evaluations at the sample scale, that incorporate specific agricultural management techniques need to be further explored.This paper establishes an agricultural management evaluation system at sample-scale based on the DSR logical framework. The capital- and labor-related indicators are used as system Drivers, technical indicators resulted from soil management and soil properties to characterize the management Status, and economic output-related indicators as system Responses. Then, a comprehensive index is calculated to inform the economic characteristics, ecological friendliness, and soil health status. As the case study, three distinct agricultural soil management systems of apple orchards in Chinese Luochuan were assessed. The results show that organic-management system is superior for excellent management skills, the conventional management system is lowest in the index due to inferior drivers and technical indicators. The green- management system is middle one. The method is useful for evaluating the soil management system in the similar agricultural areas in the world.
Satellite observations of energetic electron precipitation effect on the polar vortex
Authors: Salminen Antti , Asikainen Timo , Mursula Kalevi
Published: March 2024

Wintertime stratosphere and mesosphere are dominated by the polar vortex, a strong westerly wind system surrounding the pole. Polar vortex is variable and can even temporarily collapse during the winter, especially in the northern hemisphere. Several studies have shown that energetic electron precipitation (EEP) strengthens the northern polar vortex. Precipitating electrons come from the near-Earth space, the magnetosphere, and precipitate to the high-latitude thermosphere and mesosphere. There EEP forms odd nitrogen and hydrogen oxides (NOX and HOX) which destroy ozone and affect the temperature in the middle atmosphere. Most studies of the EEP effect on polar vortex have used reanalysis datasets which are based  on both observations and models. However, most reanalysis datasets are limited to stratospheric heights. We study here the EEP effect on the polar vortex and the modulation of this effect by planetary waves in the stratosphere and mesosphere with satellite measurements of EEP (POES/MEPED) and atmospheric properties (Aura/MLS). We derive the Eliassen-Palm flux, a measure for planetary wave activity, and the zonal wind from geopotential height observations. We show that EEP strengthens the stratospheric polar vortex, as found in earlier studies based on reanalysis data, but weakens the mesospheric polar vortex in the northern hemisphere. We also show that the EEP effect on polar vortex depends on the latitudinal distribution of planetary waves in the stratosphere and mesosphere.
Assessment of groundwater resources resilience to future climate change impacts using a high-resolution aquifer model: the case of the Emilia-Romagna region in Italy
Authors: Delfini Ilaria , Chahoud Andrea , Zamrsky Daniel , Montanari Alberto
Published: March 2024

Aquifer depletion and over-exploitation of groundwater through increased pumping are well known global challenges. The impacts of these groundwater withdrawal on aquifer storage and groundwater recharge need to be carefully studied to assess their effect on groundwater conditions in regions where extensive groundwater withdrawals occur. The Emilia-Romagna region in Italy is an excellent case of a highly monitored aquifer system playing an essential role for water supply for civil, agricultural, and industrial use. A large agricultural plain is located in this area, and its subsurface consists of multiple aquifers at different depths in fluvial sediment deposits of several hundred meters thickness in total, underlaid by marine sediment deposits. Large amount of detailed information on aquifer characteristics, water withdrawals, and water table levels is available and enables the calibration of a high-resolution dynamic three-dimensional groundwater model. The MODFLOW 6 numerical code is used in our study to build the aforementioned groundwater model. This model is based on a previous application of MODFLOW to the whole Emilia-Romagna area by the Regional Agency for Environmental Protection (ARPAE), and extends over a wide area east of the Secchia River. Our MODFLOW 6 groundwater model provides satisfactory performances, based on validation with piezometric levels over a time span of 17 years.Banking on the above detailed groundwater model results and performance, we analyse aquifer resilience to climate change and groundwater withdrawals, by running simulations with assigned perturbations of the current input data. We also analyse the future state of groundwater levels according to predictions provided by global climate models. The aim is to get an insight of the combined effects of changes in natural and artificial stresses on groundwater levels in the Emilia-Romagna region. This, in turn, would provide a guideline for sustainable aquifer management under different climatic conditions improve the resilience of regional aquifers.
Stand age diversity affects forests' resilience and stability, although unevenly.
Authors: Vangi Elia , Dalmonech Daniela , Cioccolo Elisa , Marano Gina , Bianchini Leonardo , Puchi Paulina , Grieco Elisa , Cescatti Alessandro , Chirici Gherardo , Collalti Alessio
Published: March 2024

Tree age plays an essential role in forest ecosystems' functioning by affecting structural and physiological plant traits that modulate the water and carbon budgets. On the other hand, tree age distribution in forests depends on population dynamics and, therefore, on the balance between tree mortality and regeneration events, which are ultimately controlled by natural and anthropogenic disturbances. Therefore, the human-induced modulation of the tree age distribution in forests represents a significant and not fully explored pathway to optimize the stability and resilience of forests.To examine the influence of age distribution on the stability and resilience of forest carbon budget under current and future climate conditions, we applied a biogeochemically process-based model to three past-managed forest stands and modeled their stability and resilience in terms of Net Primary Production (NPP) in the future as undisturbed systems. The model was forced with climate outputs of five Earth System Models under four representative climate scenarios plus one baseline climate scenario over a matrix of 11 age classes for each forest. We found that the NPP peak was reached in the young and middle-aged class (16- to 50-year-old) regardless of the climate scenario, as ecological theories postulate. Under climate change scenarios, the beech forest showed an increasing NPP as well as stability with increasing atmospheric CO2 and temperature across all age classes, while resilience remained stable. Conversely, in the spruce and Scots pine-dominated sites, NPP decreased under climate change scenarios. In coniferous stands, stability and resilience seem to be controlled mainly by age rather than the climate, with the older stands being more stable and resilient under all scenarios.These findings highlight the importance of considering age classes and species-specific responses when assessing the impacts of climate change on forest stability and resilience, calling for tailored management strategies to enhance the adaptability of forests in the face of changing climatic conditions, reflecting the different species and age-dependent responses to climate.