bluuebunny/crossref_metadata_2025 huggingface dataset:
Microplastic transport in European river networks
Authors: Büttner Olaf , Schwab Alexander , Katterfeld Christiane , Schmidt Christian , Borchardt Dietrich
Published: March 2024

Microplastics (MP) enter the aquatic environment through both diffuse and point sources, and are transported through the river networks into the seas and oceans. MP threatens the aquatic ecosystems and are present in water, sediment and biota. One of the main entry paths of MP pollution are wastewater treatment plant (WWTP) effluents as well as untreated surface runoff and combined sewer overflows (CSO).In this study, we aimed to estimate the average annual load of MP to the Seas and Oceans for 125 European catchments of different sizes.We coupled a mass balance model modified adapted from (Bollmann et al. 2019) and a transport model representing the river network as graph theory network (GTN). The GTN is based on the HydroShed network (Lehner et al. 2008) with WWTPs inserted as additional nodes. The partitioning of MP was calculated for three sinks (sewage sludge, river sediments, load to the sea) relying on literature-derived MP concentrations from untreated surface runoff, combined sewer overflow, and WWTPs effluents. Concentrations for average discharge conditions were calculated for all stream segments using steady-state discharge data from the HydroShed database.Based on 125 European catchments containing approximately 75% of the European WWTPs with population equivalents > 2000, we found that 77% of MP entering the river network originates from WWTP effluents, the remaining 23% is sourced from untreated surface runoff and combined sewer overflow. Of the MP that has entered the river systems, 24% are transported to seas and ocean while 76% accumulate in the river sediment. The most sensitive parameters in the model related to the loads to seas and oceans are sedimentation rates.In a next step, the model will be updated with improved hydrological parameters. Furthermore we will apply it to future scenarios of hydro-climatic and socioeconomic conditions. As the HydroShed database is globally available, the model can be applied to other regions of the world.ReferencesBollmann, U.E., Simon, M., Vollertsen, J. and Bester, K. (2019) 'Assessment of input of organic micropollutants and microplastics into the Baltic Sea by urban waters', Marine Pollution Bulletin, 148, 149-155, available: http://dx.doi.org/https://doi.org/10.1016/j.marpolbul.2019.07.014.Lehner, B., Verdin, K. and Jarvis, A. (2008) 'New global hydrography derived from spaceborne elevation data', Eos, Transactions American Geophysical Union, 89(10), 93-94.
Response of suspended sediment to natural and anthropogenic factors in the Guangdong-Hong Kong-Macao Greater Bay Area’s fish ponds over the Past 40 Years
Authors: Zhou Tao , Yang Xiankun
Published: March 2024

Suspended sediment is closely linked to nutrients, pollutants, and heavy metals, profoundly affecting aquatic ecosystems and widely recognized as a vital indicator of inland water health. Consequently, Suspended sediment concentration (SSC) can affect the growth of aquatic organisms in fish ponds, posing a substantial threat to aquaculture production. However, research on the long-term spatial and temporal dynamics of SSC, along with its response to various natural and anthropogenic factors in small water bodies like fish ponds, remains relatively scarce. This study aims to recalibrate current unified models using measured data to derive a more applicable SSC retrieval model specifically for the Guangdong-Hong Kong-Macao Greater Bay Area (GBA). Using Landsat top-of-atmosphere reflectance data from Google Earth Engine (GEE), the recalibrated model was utilized to generate SSC data for fish ponds in GBA spanning from 1986 to 2019.The results indicate that SSC in GBA fish ponds is significantly elevated during spring and summer compared to autumn and winter, with spring SSC recording the highest levels in most years. In the last 34 years, there has been a substantial overall decline in SSC in fish ponds, with an almost 50% reduction in the annual average SSC. Notably, this reduction was most pronounced in the northern, western, and eastern regions, resulting in a spatial pattern of higher SSC concentrations in the central and southern areas and lower concentrations in the surrounding regions. Correlation analysis unveiled substantial relationships (P < 0.01) between SSC interannual variations and factors like wind, speed, river sediment load, and NDVI, except for precipitation (P > 0.05). The surrounding land use of fish ponds and their proximity to rivers emerged as critical determinants influencing the spatial distribution of SSC. Furthermore, diverse aquaculture activities, such as the pond's farming cycle and production, play a significant role in regulating SSC, thereby influencing its temporal and spatial variations. GBA is one of China's highly developed aquaculture regions with dense populations, thus rendering the findings of this study valuable from both economic and ecological perspectives.
ALIX: a radio interferometry based location tracking system for pioneering astronauts on Mars
Authors: Kapitein Daan , van den Ende Sam , Kleinhans Roland , Sihol Edward , Naglis Rudis , Roosenbrand Wessel , Timmer Sjoerd , Jordans Roel , Vertegaal Niels , Brinkerink Christiaan
Published: March 2024

In the context of planetary exploration, precise local navigation solutions are critical. Currently there is no satellite network available on Mars that can facilitate navigation. Current methods of navigation on Mars use for example accelerometers, gyroscopes and celestial positioning. These methods lead to large errors in location over time. The Astronaut Location Interferometry eXperiment (ALIX) proposes an alternative way of navigation for early Mars exploration. ALIX aims to perform live location tracking of astronauts or vehicles using a compact mobile radio transmitter and an array of receiver stations. Meter-scale accuracy is expected over a tracking range of a few kilometres. The system can be deployed from a landing site. The tracking range can be extended by deploying additional receiver stations further away from the landing site, making this a very scalable solution.The proposed localisation method makes use of a technique called interferometry, commonly used in radio astronomy. The astronaut is equipped with a transmitter broadcasting a continuous radio signal. Various receiver stations measure the phase of the received signal every second. This received phase is dependent on the location of the source, time of transmission and time of measurement. Using phase differences between antennas, the location of the source is reconstructed. A minimum of three receiver stations is needed for successful tracking, with the use of more receivers adding range, robustness and accuracy. The different receiver stations can be synchronized using stationary beacons or a local Wi-Fi network, keeping the localisation accurate over time. Multiple astronauts and vehicles can be tracked at the same time by providing each with a transmitter broadcasting a unique frequency.ALIX will be tested during the AMADEE-24 mission. Ultimately ALIX will be developed into a reliable system for limited-range location tracking, easily deployable by pioneering missions using minimal recourses and infrastructure.
Exploiting satellite techniques for volcanic deposits mapping: the case of 2021 Mt. Etna eruptions
Authors: Dozzo Maddalena , Lucchi Federico , Scollo Simona
Published: March 2024

During explosive eruptions tephra fallout represents one of the main volcanic hazards and can be extremely dangerous for air traffic, infrastructures, agriculture, and human health.The technological advancements and increasing availability of high-resolution satellite imagery have offered new possibilities for mapping volcanic deposits related to an individual eruptive event. Spatial resolution is one of the main limitations in deposit mapping, together with the revisit time of satellites, particularly in rapidly evolving situations.Here we present a new technique aimed at identifying the urban areas covered by tephra after an explosive event based on the processing of PlanetScope satellite imagery. These recent multispectral data are acquired from a constellation of over 180 microsatellites and exhibits a relatively high spatial resolution (~ 3 m pixel size) covering once a day each point in the Earth surface.Our technique is based on the introduction of a new index that we call ‘Tephra Fallout Index (TFI)’ computed from the mean reflectance values of the near infrared (NIR) band analyzing pre- and post-eruptive data in paved areas adjacent to the summit craters of Etna and more distal paved areas, to have an overall view of the distribution of the tephra deposit.The objective of the proposed method is to find any variations between the pre- and post-eruptive reflectance values in the selected areas, exploiting the different ways that different materials exhibit (in this case tephra and cement) to reflect light.We use the cloud-based geospatial analytic Google Earth Engine (GEE) computing platform and define a dynamic threshold for the TFI of different eruptive events to distinguish the areas affected by the tephra fallout. We demonstrate our technique by applying it to the eruptive events that occurred in 2021 at Mt. Etna (Italy), which mainly involved the eastern and south-eastern flanks of the volcano, sometimes two or three times within a day, making field surveys difficult. Whenever possible, we compare our results with field data and find an optimal match. The use of satellite imagery acquired from microsatellite constellations, such as PlanetScope, providing an optimal compromise between spatial and temporal resolution, may prove fundamental for identifying tephra deposits during eruptive episodes, such as those occurred in 2021 at Mount Etna volcano. Our method provides a near real time result, making it ideal also for the mapping of other hazardous events worldwide.
Using peroxy radical measurements from chemical amplifiers to quantify ozone production rates in the troposphere
Authors: Dusanter Sébastien , Abichou Goufrane , Lahib Ahmad , Jamar Marina , Chen Weidong , Fuchs Hendrik , Novelli Anna , Färber Michelle , Rohrer Franz , Tomas Alexandre
Published: March 2024

Ozone (O3) is a criteria air pollutant in the troposphere and powerful oxidant that damages cellular tissue along our respiratory tract, causing distress, and crops and other plants, decreasing primary productivity in the environment. O3 is also a greenhouse gas that is responsible for ~12% of the anthropogenic global warming since 1750. Unlike other criteria air pollutants that have major primary emission sources, O3 is entirely a secondary pollutant and has a complicated non-linear dependence on its precursors nitrogen oxides (NOx) and volatile organic compounds (VOCs). For instance, lowering some O3 precursors can actually increase local O3 concentrations under certain conditions. Ozone concentrations observed at monitoring sites not only depend on the local chemistry but also on the transport of air masses containing O3 from other locations, and on dry deposition. It is therefore essential to clearly understand how these physicochemical processes impact ozone budgets to design efficient mitigation measures at targeted sites.Simultaneous measurements of ozone production rates, P(O3), and ozone concentrations can provide a detailed picture of the ozone budget at a monitoring site, including a critical assessment of the O3-driving processes mentioned above. In this study, we will present how a chemical amplifier can be used to infer P(O3) from peroxy radical measurements and we will discuss the reliability of this methodology. We will present results from ozone production experiments that were performed in the SAPHIR atmospheric chamber during the ROxCOMP (ROx Comparison) campaign. We will show how P(O3) values inferred from the chemical amplifier compare to values derived from observed Ox (O3+NO2) changes in the chamber for various experiments using contrasting conditions of VOCs and NOx.Acknowledgments. This work is supported by the French national research agency (ANR) under LABEX-CaPPA (ANR-11-LABX-005-01), the CPER-CLIMIBIO program, the French national program LEFE/CHAT INSU and the Hauts-de-France region of France. This project has received funding from the European Union’s Horizon 2020 research and innovation programme through the ATMO-ACCESS Integrating Activity under grant agreement No 101008004.
Vegetation to cool cities: a synthesis based on eddy covariance measurements in European cities
Authors: Guidolotti Gabriele , Shaukat Sundas , Ciolfi Marco , Mattioni Michele , Nicolini Giacomo , Sabbatini Simone , Calfapietra Carlo , Papale Dario ,   Sites PI
Published: March 2024

Global warming and urbanization growth are accelerating and fuelling typical urban stressors including microclimate alterations with an intensification of urban heat islands (UHI). UHI areas are characterized by warmer temperatures with respect to the surrounding rural areas, affecting human health and mortality. Trees and urban green areas (UGAs) have been shown to be crucial in reducing the UHI because of the canopy transpiration-induced cooling: by turning liquid water to vapor absorbing heat energy from the surrounding environment, solar radiation is converted into latent heat flux, which lowers air temperatures surround. In this study conducted over 10 European cities we investigated if and how much UGAs impact latent heat fluxes and the related ambient air cooling, and how UGAs could be used to develop more habitable and sustainable urban environments. Specifically, the objectives of the study are to: 1) assess the impact of the green areas in cooling down the air temperature in summer months using in situ eddy covariance (EC) measurements and 2) assess the role of the environmental factors driving the latent heat fluxes and, consequently, the related cooling of urban microclimate. Results confirm that green areas within urban environments are key elements for enhancing the summer air cooling and thus the well-being of local inhabitants.
Tracking sea salt instead of saline water
Authors: Döös Kristofer , Koszalka Inga , Axell Lars
Published: March 2024

Lagrangian (parcel following) approach is a powerful method to diagnose the modelled flow and associated property changes in atmosphere and ocean and is used to investigate causal links between the property changes between the different regions. The salt in the saline sea water has traditionally been tracked as tracer property or a marker of sea water despite the seawater is constituted of both water and salt molecules. In the present study, we propose an new approach relying on tracking  separately the mass of fresh water and salt in the ocean. As a study region we have chosen the Baltic Sea, a semi-enclosed sea characterised by a distinct estuarine circulation due to river runoff and deep salt water inflow from the North Sea. The salt was tracked by summing over both the advective and diffusive salt fluxes simulated by the circulation model NEMO. Salt and water trajectories were computed with the mass conserving TRACMASS model, where each trajectory tube is in units of m3/s of water flux or kg/s of salt flux. The preliminary results show a clear difference between salt and water trajectories, where e.g. the salt trajectories (red in the attached Figure) do not reach as far into the Baltic Sea as the (blue) water trajectories. Many diagnostics such as the residence time and age also differ, which opens up a completely new vision of the ocean circulation.Figure: Water mass (blue) and salt mass (red) trajectories entering the Baltic Sea through the Danish straits.
High-resolution paleoseasonality records across the Late Maastrichtian Warming Event (Late Cretaceous) as revealed by oyster shells from the Maastrichtian type area (SE Netherlands, NE Belgium)
Authors: Willems Anthea , Jagt John W. M. , Vellekoop Johan
Published: March 2024

Because our modern world is characterized by climate change, it is useful to study climate conditions of past greenhouse worlds in order to obtain a better understanding of what a similar world would entail. An example of such a past greenhouse climate is represented by the Late Maastrichtian Warming Event (LMWE), a global temperature increase of approximately 2.5-5°C that occurred 300-100 kyr prior to the Cretaceous-Paleogene boundary meteorite impact and the ensuing mass extinction. This warming event has traditionally been linked to a major pulse of Deccan Traps volcanism. Previous research has also recorded the LMWE in the Maastrichtian type region (SE Netherlands, NE Belgium), where this event is marked by characteristic blooms of the dinoflagellate Palynodinium grallator and a sudden appearance of hermatypic corals. A recent study using clumped-isotope analyses on fossil bivalves has shown that the LMWE was characterized by a 5 degrees warming in average annual sea water temperatures in this region (40° paleolatitude). However, little is known about changes in seasonality across this warming event, as high-resolution paleoseasonality reconstructions have not been previously attempted. Here, we present a seasonal, stable-isotope record through the LMWE for the Maastrichtian type area (SE Netherlands, NE Belgium), using stratigraphically well-constrained oyster specimens. This new record contributes to our understanding of the effects of a global warming event on seasonality in a mid-latitude shelf sea. Consistent with previous results, we have found a decreasing trend in δ18O values in the interval corresponding to the peak of the warming event, followed by an increase during the cooling-down period. Our results show that the LMWE also had profound effects on the seasonality in the Maastrichtian type area. The δ18O seasonality temporarily decreased at the onset of the event, suggesting that winter temperatures warmed disproportionately. Possibly, this could have allowed the previously recorded establishment of hermatypic corals in the region. Subsequently, seasonality increased again through the warming event, with the highest seasonality recorded in the later part of the event. Over the coming months, additional oyster specimens will be assessed for both stable and clumped isotopes to obtain a more complete record of seasonality throughout the LMWE.
Investigating fuels, fuel moisture and fire severity in the Bohemian-Saxon Switzerland region (Czech Republic/Germany): the need for dynamic fire risk assessment and management 
Authors: Marrs Christopher , Beetz Kristina , Kranz Johanna , Bauer Konrad , Avouris Evripidis , Poděbradská Markéta , Kinalczyk Daniel , Forkel Matthias
Published: March 2024

Until recently, forest fires were considered a rare phenomenon in the temperate forests of Central Europe due to the moderate summer temperatures and the humid climate. However, many of those forests (e.g. monocultures of Picea abies, Norway Spruce) were affected by bark beetle infestations in the past years and recent fires such as in the Bohemian-Saxon Switzerland in 2022 raised widespread debates about the effects of forest mortality on fuel accumulation and hence fire occurrence and severity. Here we mapped and investigated fuel types, fire severity and started to continuously monitor fuel moisture in the Bohemian-Saxon Switzerland. We enhanced a European fuel type classification with a class for dead and dying spruce and mapped fuel types. Satellite observations from VIIRS, Sentinel-2 and Landsat were used to map fire intensity and severity of the fire from 2022.We found the highest fire intensities at sites with dead spruce forests and single beech trees. Burn severity was moderate with high variability across all fuel types but highest severities occurred in dead spruce stands. Fire severity derived from satellite observation correlated positively with char height and torched trees, especially seen in dead spruce stands, which was likely caused by the high amount of dry fine woody debris and the initial natural regeneration. Our results demonstrate that surface fuel accumulation from past bark beetle disturbances resulted in more intense fires and higher burn severity. The results demonstrate that the recent rapid changes in Central European temperate forests cause a need for a dynamic mapping and monitoring of fuel types and fuel moisture for fire risk assessment and for cross-border fire risk management in landscapes previously not considered as fire-prone.
Increased temperature-related newspaper coverage and more negative sentiment during hot and cold extremes
Authors: Bogdanovich Ekaterina , Schäfer Mike S. , Brenning Alexander , Reichstein Markus , De Polt Kelley , Guenther Lars , Frank Dorothea , Orth René
Published: March 2024

More frequent, intense, and prolonged temperature extremes due to climate change increase the risk of human morbidity and mortality. However, public perception of these risks is often low, while people's awareness is crucial to reducing the health impact of temperature extremes. News media plays a key role in raising awareness by providing essential information on heat waves and cold spells such as releasing warnings, sharing weather forecasts, and discussing impacts. Any sentiment conveyed within newspaper articles about temperature extremes, either through positive, negative, or neutral phrasing, can influence the audience's perception of risk and, potentially, their actions. Newspaper coverage of temperature extremes and the related sentiment may be influenced by multiple factors other than the actual temperature anomalies, such as political alignment or editorial decisions, but also potentially the countries’ vulnerability to climate change. In this study, we analyze and compare the sentiment of temperature-related newspaper articles in eight countries (Israel, Malaysia, New Zealand, Philippines, Singapour, Pakistan, South Africa, and the United Kingdom) with different climates and societal vulnerabilities to climate change (food, water, health, ecosystem services, human habitat, and infrastructure). We consider leading English language, national newspapers and use daily maximum temperature data from the day of each article’s publication from the ERA5 reanalysis. The sentiment is determined in an automated way based on the fraction of positive and negative words in text. In addition to the sentiment, we determine whether or not each article mentions climate change. We find clear differences during times of extreme temperatures versus times with near-normal temperatures in all countries. During days with comparatively cold or warm temperatures (i) more temperature-related articles are published, (ii) their sentiments are more negative, and (iii) climate change is mentioned less frequently. While the latter finding is surprising, it suggests that there are unobserved confounding factors that require further research, which might relate to other events and anomalies occurring simultaneously. A comparison of the results across countries shows more negative sentiment and fewer mentions of climate change in countries with higher climate change vulnerability. Being aware of these media reporting patterns of extreme temperatures may help media outlets reassess their role in aiding public health responses.
Vegetation types influence fine-scale drought impact on land surface cooling and burn patterns in the Siberian coastal tundra
Authors: Rietze Nils , Assmann Jakob , Schapeman-Strub Gabriela
Published: March 2024

In 2020, the Northeastern Siberian lowland tundra faced an extreme drought and unprecedented wildfires. The burning of carbon-rich soils in this region can release large amounts of carbon, worsening climate change and Arctic warming.  However, we know little about of how droughts impact vegetation and how this vegetation might become fuel for large fires in the typically wet landscapes of the Northeastern Siberian lowland tundra. We studied the impact of the extreme summer drought in 2020 on the tundra vegetation and the resulting burn patterns in the Indigirka lowlands using a combination of in-situ, thermal, and multispectral remote sensing data from drone and high-resolution satellite imagery. The fine-scale vegetation types revealed increased landscape-wide drought susceptibility indicated by an overall loss of land surface cooling. This suggests a shift towards an energy budget dominated by sensible heat flux, which may feed back and intensify the heatwave.  Further, we found that mostly dry vegetation types were affected by fire in the NE Siberian coastal tundra, while wetter vegetation types did not burn, leading to a fine-scale heterogeneous burn pattern. Our results indicate that the enhanced drought susceptibility of vegetation types may have led to higher fire fuel connectivity of the tundra landscape. Consequently, this may have resulted in the large burn extents observed in 2019 and 2020. Our analysis is an effort toward the prediction of fire fuel connectivity and fire management in remote Arctic areas.
The climate impact of tropical peatland degradation
Authors: Dommain René , Frolking Steve , Jeltsch-Thömmes Aurich , Joos Fortunat , Couwenberg John , Glaser Paul , Cobb Alexander , Harvey Charles
Published: March 2024

Southeast Asia is a global hotspot of peatland degradation and related greenhouse gas emissions. Anthropogenic impacts, mainly associated with agricultural conversion, shift Southeast Asian peatlands from carbon sinks to significant carbon sources. Here we first describe the impacts of anthropogenic drainage on landscape-scale carbon dynamics of individual peatlands and then use an impulse‐response model of radiative forcing to quantify the climate impacts of peat-carbon losses. Whereas water-table elevation (i.e. drainage depth) determines the magnitude of CO2 emissions at the site-scale, the geometric arrangement of artificial drainage networks determines carbon losses on the landscape-scale. Among all peatland greenhouse gas fluxes, the rapid release of large quantities of CO2 with lowered water tables has the greatest impact on atmospheric radiative forcing. While peat accumulation in undisturbed peatlands produces a slowly increasing net radiative cooling, drainage, within decades, causes a shift in radiative forcing to a positive atmospheric perturbation (i.e. net warming), which can persist for centuries to millennia. The pace of this shift in radiative forcing and the magnitude and duration of the warming effect depend on the age and carbon pools of peatlands.
Structural observations of the northern North Sea: insights into rift failure dynamics
Authors: Peron-Pinvidic Gwenn
Published: March 2024

Lithospheric extension leads to rift formation and may continue to the point of breakup, with oceanic ridge initiation and the formation of two conjugate rifted margins. In some settings, extension can cease, and the rift may be abandoned. These so-called failed rifts archive snapshots of early phases of deformation, with geometries that may help better constrain the parameters that can prevent a rift from reaching breakup, such as lithospheric rheology, thermal state, rift opening direction and rate, inheritance.This contribution summarizes a study of the Norwegian Continental Shelf which includes the North Sea Rift and the Møre and Vøring rifted margins. We proceeded to the interpretation of a new dataset of deep penetrating seismic reflection profiles and worked at the regional scale, deliberately ignoring local particularities, to focus on the large-scale structural picture. The aim is to list architectural similarities and differences between the failed rift and the successful rifted margins.The mapping shows that the North Sea structural geometries and basement seismic facies are very similar to the observations listed for the adjacent Møre and Vøring rifted margins. Various types of tectonic structures are observed, from thick anastomosing shear zones possibly evolving into core-complex geometries, to composite large-scale detachment faults and standard high-angle normal faults. These are categorized into five classes and interpreted as exemplifying the rift tectonic evolution through distinct generations of deformation structures that can activate, de-activate and re-activate. Based on these observations, rift failure dynamics are discussed, and it is proposed that the North Sea rift abandonment may not be related to pre-rift local conditions but rather to the ability to initiate specific tectonic structures such as distal breakaway complexes.
Vegetation restoration potential in the drylands of China under water constraint
Authors: Lin Huiqing , Li Yan
Published: March 2024

As an essential pathway for nature-based solutions, vegetation restoration can effectively absorb carbon sequestration and mitigate global warming. However, the excessive water consumption by vegetation expansion may create potential water conflicts between natural ecosystems and human systems, and even exacerbate local water shortages, especially in water-limited dryland regions. By evaluating water availability using multiple datasets, this study explored the vegetation restoration potential and the allowable vegetation conversion in China’s drylands under the constraint of water availability. We found that the additional water resources available for vegetation restoration in China’s drylands were 12 ± 114 mm (median ± SD) from 2003 to 2018 but it decreased over the period (-1.18mm/year). 43.3% of the dryland area had water deficits, after considering current vegetation and human water consumption. Under current water constraints, additional Gross primary productivity (GPP) that could be restored ranged from 8% to 12% depending on vegetation types (10.5% for forests, 11.6% for grasslands, 7.8% for irrigated crops, and 8.9% for rain-fed crops). In water surplus areas, primarily in the south and east of China’s drylands, most vegetation conversions toward higher-water-consumption types were allowed to occur. In water deficit areas, the west of drylands, even converting all the existing vegetation to less water-intensive types would not compensate for the water deficit in most regions, suggesting local vegetation may have exceeded the water-carrying capacity. Our research highlights the importance of the potential water constraint of vegetation restoration in drylands and provide a guidance for decision-making vegetation restoration while ensuring water sustainability. Next, we will explore the potential for vegetation restoration under different climate change scenarios (e.g., ssp126, ssp370, and ssp585). 
VLBI processing in FocusPOD
Authors: Fernández Carlos , Fernández Marc , Fernández Jaime
Published: March 2024

GMV is developing FocusPOD, a suite of tools for POD and geodesy, powered by GMV MAORI, a new GMV in-house Flight Dynamics & Geodesy library, written from scratch in modern C++ and python. FocusPOD supports several projects led by GMV, including the operational provision of Precise Orbit Determination (POD) products of the Copernicus Sentinel satellites in the frame of the CPOD Service, the simulation of tracking data for Galileo 2nd Generation (G2G) System Test Bed, and other space debris and flight dynamics activities.FocusPOD is currently capable of processing GNSS data, with a focus on on-board receivers to support POD, and Satellite Laser Ranging (SLR), mostly used in CPOD as an external orbit validation source. Capabilities to process DORIS have been recently added, also targeting POD applications as a first step. GMV’s roadmap for FocusPOD include processing VLBI in addition to these 3 techniques, with the target of becoming a reference software for the geodesy community.This contribution intends to present FocusPOD roadmap to incorporate VLBI processing capabilities, describing the modelling challenges that have been identified and the various steps that will be taken to finally be able to process VLBI and provide VLBI-based ITRF products. As part of this roadmap, other parallel activities to tie together the rest of the techniques will also be undertaken and described, mostly related to the ground-based processing of GNSS, SLR and DORIS data.
LOFAR Observations of the Initial Stage of IC Dart Leaders
Authors: Hare Brian , Scholten Olaf , Ťureková Paulina , Cummer Steven , Dwyer Joseph , Liu Ningyu , Sterpka Chris , ter Veen Sander
Published: March 2024

In previous work we have found that dart leaders quench needle activity; where dart leaders are charge pulses that re-trace previously established lightning leader channels, and needles are small repeating negative discharges that propagate away from positive lightning channels. We hypothesized that dart leaders could be quenching needles by carrying negative charge away from the region of needle activity. Therefore, in order to further explore the interactions between dart leaders and needles, we are investigating the beginnings of different dart leaders with the LOFAR radio telescope, which uses hundreds of antennas in northern Netherlands to image lightning in the 30-80 MHz band with meter and nanosecond level accuracy. We have found that, consistent with previous work, dart leaders start slow with weak radio emission and then accelerate over a period roughly around 50 µs in duration until they reach a maximum speed and radio intensity. However, we also observe that the power of the radio emissions from the dart leaders exhibits large, randomly-timed, variations. These variations do not appear to be a form of leader stepping. The time-differences between individual peaks in the time trace is significantly longer than the width of each peak (or pulse) that is dominated by the antenna function, (FWHM ~ 50 ns). One possible explanation could be that the power fluctuations are consistent with Poisson statistical variations of radio sources (possibly streamers), which would imply that at any point in time the radio emission is dominated by a small number of strong emitters, as opposed to millions of small streamers. A second possible explanation is that the fluctuations could be due to small-scale structural variations along the previously established plasma channel, which we have observed in previous work.
Plastic input and dynamics in industrial composting
Authors: Peneva Stoyana , Phan Le Quynh Nhu , Munhoz Davi , Wrigley Olivia , Wille Flora , Macan Giovana P.F. , Doose Heidi , Amelung Wulf , Braun Melanie
Published: March 2024

Despite various attempts by composting facilities to remove plastics from compost, high levels of particularly small microplastics (1 µm - 5 mm, MiPs) are detected in compost.To elucidate the potential removal or enrichment of MiP during the composting process, we first analyzed the input of macroplastics (> 20 mm, MaPs) via bio-waste collection in an industrial composting plant. Then, we further determined MiPs at five different stages during the composting process (before and after distinct shredding and screening processes), as well as in the water used for irrigation.We found varying total concentrations of MaP in the bio-waste collected from different municipalities, ranging from 0.36 - 4.72 kg ton-1 bio-waste, with polyethylene (PE) and polypropylene (PP) being the most abundant types. Further, we found a similar presence of “foil” and “non-foil” plastics, with 0.824 ± 0.34 kg ton-1 and 0.83 ± 0.34 kg ton-1 bio-waste, respectively; only 0.3 ± 0.1 kg ton-1 bio-waste of biodegradable plastic was found. The total concentration of MaP and MiP increased from 12 items kg-1 before shredding to 34 items kg-1 bio-waste in the final compost, indicating a relative enrichment of the number of particles during the process. Analyzing the rain water used for moistening the compost (collected on the roof of the compost facility) revealed that already high amounts of PE, polyamide (PA) and PP particles with sizes of 6 - 70 µm were found in rainwater (22,714 ± 2,975; 3,108 ± 748 and 685 ± 398 particles L-1, respectively). These plastic loads were 1.4 to 5-fold lower in the process water collected after irrigation, indicating a co-contamination of compost by irrigation. This study highlights the importance of reducing plastic input via bio-waste, as it is one of the main sources for MiP contamination of compost, while also recognizing the challenges in effectively removing MiP during composting. The complex dynamics of MiPs, i.e. the enrichment of small MiPs, is problematic as small particles in particular have many ecotoxicological properties. We could identify irrigation water as a plastic source for compost, an input pathway that has been overlooked so far. Therefore, our results underline the need for comprehensive strategies to tackle plastic pollution throughout the composting cycle, from bio-waste input to final compost products. 
Elucidating formation of highly oxygenated organic molecules (HOMs) from α-pinene ozonolysis with isotopic labelling
Authors: Meder Melissa , Graeffe Frans , Luo Jingyi , Luo Yuanyuan , Varelas Jonathan , Peräkylä Otso , Kurtén Theo , Rissanen Matti , Geiger Franz , Thomson Regan , Ehn Mikael
Published: March 2024

Upon oxidation, some volatile organic compounds (VOCs) have been shown to go through a rapid process called autoxidation forming highly oxygenated organic molecules (HOMs). The exact autoxidation pathway taken affects the formation rates and the properties of the HOMs, however, a comprehensive step-by-step mechanism of HOM formation has not been described for any system of atmospheric relevance. In the autoxidation process, peroxy radical (RO2) intermediates undergo intramolecular hydrogen abstractions (H-shifts) followed by oxygen (O2) additions. This process can be monitored using chemical ionisation mass spectrometry and selective deuteration, where the precursor molecule has had the hydrogen atoms (1H) of a specific carbon replaced with deuterium atoms (2H). In this work, we studied the initial formation pathways of HOMs in reactions of the monoterpene α-pinene with ozone. We had access to all separately deuterated carbon positions in α-pinene that have hydrogens, i.e. we had in total eight different selectively deuterated α-pinenes. We were able to determine which of the deuterated precursors were prone to losing D during the (aut)oxidation process, which helped us understand the pathways leading to HOM formation.
Solar Orbiter: Recent science highlights and mission status 
Authors: Mueller Daniel , Zouganelis Yannis , De Groof Anik , Williams David , Walsh Andrew , Janvier Miho , Nieves-Chinchilla Teresa , Lario David
Published: March 2024

This contribution will summarise recent science highlights of the ESA/NASA Solar Orbiter mission and provide a mission status update. Solar Orbiter started its nominal mission phase in December 2021, with perihelia around 0.29 au occurring every six months. The ten instruments onboard provide high-resolution imaging and spectroscopy of the Sun and corona, as well as detailed in-situ measurements of the surrounding heliosphere. Together, these observations enable us to comprehensively study the Sun in unprecedented detail and determine the linkage between observed solar wind streams and their source regions on the Sun. Solar Orbiter’s science return is significantly enhanced by coordinated observations with other space missions, including Parker Solar Probe, SDO, SOHO, STEREO, Hinode and IRIS, as well as new ground-based telescopes like DKIST. Starting in 2025, Solar Orbiter’s highly elliptical orbit will get progressively more inclined to the ecliptic plane, which will enable the first detailed observations of the Sun’s unexplored polar regions.
Mantle Transition Zone structure beneath the Central and Eastern European region based on P-to-S Receiver Function analysis
Authors: Kalmár Dániel , Michailos Konstantinos , Petrescu Laura , Hetényi György , Bokelmann Götz , Working Groups AlpArray and PACASE
Published: March 2024

The depths of mineralogical phase transitions in the mantle (at ~410 and ~660 km depth) offer crucial insights into the thermal conditions of the mantle transition zone and, by extension, the upper mantle's state and circulation. Our approach involves conducting P-to-S receiver function analysis to determine the mantle transition zone's thickness and the absolute depths of the ~410 km and ~660 km discontinuities in the Central and Eastern European region.Our workflow meticulously attends to each step, starting from data download, quality control, and culminating in the calculation of P-to-S receiver functions. We use data from multiple sources, including the AlpArray and AdriaArray Seismic Networks, the PACASE, Carpathian Basin, and South Carpathian Project temporary seismic networks, as well as the permanent stations of the Hungarian National Seismological network and of the neighboring countries. This analysis covers the time period from 2002 to 2023, involving over 860 seismological stations. Our extensive dataset, consisting of approximately 2 million three-component waveforms and over 120,000 high-quality P-to-S radial receiver functions, coupled with dense piercing-point coverage, allows us to achieve unprecedented resolution.We present Common Conversion Point cross-sections migrated with a 3D tomographic velocity model underneath the Alps, Carpathians, and the Pannonian Basin. Additionally, we aim to offer new insights into the mantle transition zone's thickness beneath intriguing regions (e.g., Vrancea zone, Alpine Tethys Ocean zone, Eastern Alps–Pannonian Basin transition zone). For a precise understanding of geodynamic processes such as slabs, mantle plumes, and volcanism, it is imperative to accurately map these boundaries.
Development of a Bayesian non-planar fault geometry inversion using geodetic seismic cycle deformation data
Authors: Wei Guoguang , Chen Kejie , Dal Zilio Luca
Published: March 2024

The geometry of faults regulates the spatial patterns of interseismic, coseismic, and post-seismic surface deformation. Geodetic techniques can measure these deformation patterns during a seismic cycle and are expected to constrain the geometry of  seismogenic faults. However, the conventional linear inversion of geodetic data is unable to simultaneously estimate the fault slip distribution and the fault geometry. In this study, we propose a Bayesian framework that treats fault geometry as a time-invariant parameter. It can individually use coseismic deformation data or simultaneously utilize interseismic, coseismic, and post-seismic deformation data to invert for both fault slip distribution and non-planar fault geometry. Within this framework, geometry evidence informed by geophysical imaging, geological surveys, and microseismicity forms the basis for establishing the prior probability density function, while geodetic observations constitute the likelihood function. Our methodology provides an ensemble of plausible geometry parameters by sampling the posterior probability distributions of the parameters using Markov Chain Monte Carlo simulation. The performance of the developed method is tested and demonstrated through inversions for synthetic oblique-slip faulting models. Results demonstrate that assuming constant rake can significantly bias fault geometry estimates and data weighting. Additionally, considering the variability of slip orientations allows for plausible estimates of non-planar fault geometry with objective data weighting.We applied the method to the 2013 Mw 6.5 Lushan earthquake in Sichuan province, China. The results reveal dominant thrust slips with left-lateral components and a curved fault geometry, with the confidence interval of the dip angles ranging between 20° and 25° and 56° and 58°. Furthermore, the application of this method to the 2015 Gorkha earthquake in Nepal sheds light on the Main Himalayan Thrust, which serves as the interface between the Indian Plate and Eurasia. This may provide new insights into future seismic potential and topographic growth in the Nepal Himalaya.
Monte Carlo Error Analysis of Lightning Interferometry with LOFAR
Authors: Turekova Paulina , Hare Brian , Scholten Olaf , Cummer Steven , Dwyer Joseph , Liu Ningyu , Sterpka Chris , ter Veen Sander
Published: March 2024

The LOFAR radio telescope works on a principle of radio interferometric imaging. It coherently sums the signal of hundreds of antennas in northern Netherlands, covering the 30-80 MHz window of the very high frequency (VHF) band of 30-300 MHz. We are using the TRI-D algorithm to extract 3-D polarization data of a lightning flash observed by LOFAR. TRI-D functions by coherently summing recorded voltages, accounting for the antenna function, polarization, and geometric time delay for each voxel. The result is split into time slices. A coherent intensity is calculated for each time slice, and the maximum of this value is set as a source location. The outcome is a reconstructed source location and polarization as seen by the LOFAR antennas. We are now exploring the accuracy of TRI-D in response to realistic parameters. In this work, we perform a Monte Carlo error analysis which simulates the voltages on each antenna from an assumed dipole emitter, adds normally distributed noise, and then reconstructs the source properties with TRI-D. The difference between the simulated input and the reconstruction gives us an estimate of the resulting error bars. We will show a detailed account of the interferometry technique that produces our data, the Monte Carlo simulation that tests the accuracy of our model and finally, our polarization results.
Ion chemistry in the Martian dayside ionosphere
Authors: Persson Moa , Vigren Erik
Published: March 2024

The ion composition of the Martian ionosphere is controlled by the ionisation of the neutral species (mainly CO2, CO and O) in the upper atmosphere and the chemical reactions that follow. The primary ions, CO2+ and O+, are reactive with O and CO2, respectively, as to produce O2+, which is the dominant ion species in the ionosphere. We apply a variety of simple chemical schemes to model the ion chemistry in the Martian dayside ionosphere using data from deep dip campaigns of the MAVEN mission. As model input we use concentrations of neutral species, as measured by the Neutral and Gas Ion Mass Spectrometer (NGIMS) onboard MAVEN, and solar EUV spectra measured by TIMED/SEE; extrapolated in distance and phase to Mars. We reach an adequate agreement between the calculated ion densities of the main ion species and those measured by NGIMS. However, the calculated ion composition does not fully match the measurements and deviations of up to a factor of 3-4 do prevail for some of the considered ion species. Several previous studies have solved similar issues by adjusting the input parameters to the calculations, such as increasing the neutral O density, reducing the neutral CO2 density or decreasing the solar irradiance. We present results from a thorough exploration of the involved parameter space and discuss possible reasons for still persisting model-observation discrepancies.