bluuebunny/crossref_metadata_2025 huggingface dataset:
Vegetation response in SE France to the millennial-scale climate variability of the last glacial period
Authors: Fourcade Tiffanie , Sanchez Goñi Maria Fernanda , Lesven Jonathan , Lahaye Christelle , Philippe Anne
Published: March 2024

Deep-sea pollen records from the Western European margin indicate that regional vegetation oscillated between open forest and steppe during the Last Glacial period (ca. 115-27 ka), in response to the millennial scale climate variability, specifically the Dansgaard-Oeschger, (D-O) cycles and Heinrich events (HE). The magnitude of the forest expansions during D-O warming events was modulated by orbital parameters. However, the vegetation response in the north-western Mediterranean region during this period remains poorly understood due to the fragmentary nature of the available sequences.In this study, we present a new well-chronologically constrained high-resolution marine pollen record from the Gulf of Lion (MD99-2343, 40°29'N, 4°01'E) documenting the vegetation response in southeastern France during Marine Isotope Stages (MIS) 4 to 2 (ca. 73-27 ka). Initial findings highlight that the extent of the temperate forest expansions in SE France, i.e. the forest colonizing the Rhône valley, in response to D-Os warming events is modulated by precession, as previously indicated by Western European margin pollen records located in the Mediterranean region below 40°N. In Western Europe, the HEs are all characterized by steppe expansions, but the new pollen analysis documents another scenario with an increase in forest cover during HE 6. We hypothesize that the combination of minima in precession and local atmospheric and marine processes in the Gulf of Lion allowed the development of the temperate forest in SE France during HE 6, while the expansion of open environments occurred in Western Europe.
The March 2022 exceptional heatwave recorded in the isotopic composition of precipitation at Dome C, East Antarctica
Authors: Dreossi Giuliano , Masiol Mauro , Zannoni Daniele , Scarchilli Claudio , Ciardini Virginia , Grigioni Paolo , Del Guasta Massimo , Stenni Barbara
Published: March 2024

An exceptional heatwave impacted on East Antarctica between March 15 and 19, 2022, causing some of the highest temperature anomalies ever measured on Earth. The heat transport was associated to an atmospheric river bringing a moisture flux from lower latitudes to inner Antarctica. Several locations, from coastal sites to the high Antarctic Plateau, experienced record temperatures. The air temperature measured at Concordia Station by the automatic weather station of the Italian Antarctic national research program (PNRA) reached a maximum of -11.7°C.The temperature signal is imprinted in the oxygen and hydrogen isotopic composition of precipitation: this is what allows paleoclimate reconstructions from the isotopic records in ice cores, although post-depositional processes such as the interactions between snow and atmosphere and within the snow column might affect the pristine isotopic signal.Since 2008, precipitations have been collected daily at Concordia Station for δ18O and δD measurements; the activities have been carried out under the PNRA project WHETSTONE and will continue in the framework of the PNRA project AIR-FLOC. Isotopic values from 2008 to 2021 range between -82.63‰ and -26.97‰ for δ18O and between -595.1‰ and -223.0‰ for δD, while water stable isotope data from February to April 2022, show unprecedented high values (δ18O =-18.97‰, δD=-147.9‰), the highest recorded over the last 15 years, in correspondence to the exceptional temperatures and snow precipitations. Moreover, the daily snowfall collected during the same period reached a cumulative value of ~4.3 mm w.e. representing ~18% of the 2022 cumulative annual value (24.1 mm w.e.)
The Mussau Ridge and Trench – news from an infant subduction zone
Authors: Brandl Philipp , Beier Christoph , Waßmund Leon , Geersen Jacob , Genske Felix
Published: March 2024

The Mussau Trench between Papua New Guinea and the Federated States of Micronesia is considered as the type locality for induced subduction initiation through transference. Despite its significant role for studying and understanding global plate tectonic cycles, little is known about its tectonic  geomorphology, lithostratigraphy, and geodynamic evolution. During research expedition SO299 DYNAMET with the German RV SONNE, the morphology and shallow structure of the Mussau Ridge was mapped along its entire length and sampled at representative locations. At the central segment, the ridge was visually mapped and stratigraphically sampled using the ROV. Here we present the first results from petrology, geochemistry and structural mapping of the ridge. Preliminary glass major and trace element data indicate a depleted MORB-like nature of the exposed crust that is in agreement with previous findings. Stratigraphically, lavas (layer 2A) and sheeted dykes (layer 2B) of the oceanic igneous crust are exposed. Whole rock trace element and radiogenic isotopes analyses are currently underway to further constrain the geochemical character of the crust and its associated mantle sources. Initial results from hydroacoustic and visual mapping indicate the presence of an active thrust system based on pristine fault scarps and large rubble piles lacking any sediment cover. However, shape and structure of the ridge vary along strike, and only the central portion holds indications for tectonic uplift. In the south and in the north, the ridge shows evidence for a strong lateral shear component. We combine the obtained results into an initial model of the tectonic evolution of the ridge and how this fits into regional plate tectonic models.
Uncertainty Quantification of Theoretical Consistent Intensity Duration Frequency (IDF) Curves of Rainfall Intensity
Authors: Amin Bushra , Bárdossy András , Haberlandt Uwe
Published: March 2024

Many water-related systems and defensive structures require the design of rainfall amounts at various durations and frequencies, commonly referred to as Intensity Duration-Frequency (IDF) curves. Usually, these curves are derived from observed data, but there is a chance that the risk has been underestimated because of various uncertainty sources. As a result, measuring the uncertainty ranges of these curves becomes essential. To do this, the regionalization of the IDF curves for BW is inspected for the propagation of possible sources of uncertainty. For each site, annual extremes are obtained for varying durations (from 5 min to 16 days), and local extreme value analysis is performed in compliance with Koutsoyiannis et al. (2021).  Following this investigation, Kriging with External Drift (KED) is used to interpolate all seven parameters of theoretically consistent IDF models for each station; this implies that no parameter remains constant across the region.  Quantiles are then retrieved for every station, duration, and given recurrence interval. The uncertainty is estimated for each of the three components of the regionalization—local parameter estimation, variogram estimation, and spatial parameter estimation—in terms of accuracy (expected error) and precision (95% confidence interval width) using bootstrapping (non-parametric) and geostatistical spatial simulations. The reason for selecting Conditional Sequential Gaussian (CSG) simulations was their capability to produce a large number of equiprobable spatial simulations. Many recent studies also demonstrated its accuracy, which is why CSG was chosen to evaluate the uncertainty from spatial simulations. Subsequently, one hundred realizations were carried out at every regionalization component to examine their ultimate impact on the regionalization of parameters and IDF curves. Afterward, combined simulations were executed for the propagation of the uncertainty from the key components to the final IDF curves.It turned out that the primary source of uncertainty in the selected regionalization process is spatial estimation, which is followed by local estimation of rainfall extremes. More specifically, the total estimation of IDF curves was mostly insensitive to variogram uncertainty. The integration of spatial simulations with local resampling yielded accurate estimates of the overall uncertainty at sampled sites, whereas at unsampled sites, the accuracy decreased based on the density and proximity of the surrounding observations. This combination was used to simulate the total uncertainty in BW via 100 runs. The results showed that, depending on the site and duration interval, tolerance ranges should be expected to be between ± 0.9-4.2 mm/h for low-recurrence intervals (less than 5 years) and ± 2.2-5.5 mm/h for high-recurrence intervals (more than 50 years), but very short durations (5 min) are relatively more uncertain than longer durations.
Pore-Size-Class Dependent Carbon Turnover in Peat Soils
Authors: Lennartz Bernd , Cambinda Rosa , Liu Haojie , Rezanezhad Fereidoun
Published: March 2024

Carbon loss from peatlands involves both gaseous emissions and a significant contribution from the water-bound fraction, specifically dissolved organic carbon (DOC), during mineralization and degradation processes. Our hypothesis proposes that DOC production is dependent on pore size, with elevated concentrations occurring in finer pores. To test this hypothesis, we extracted pore water at well-defined pressure heads (-60 and -600 hPa), representing macro- and mid-size pore domains, in degraded peat samples. Topsoil and subsoil samples exhibited soil organic matter contents of 34wt% and 57wt%, respectively. Remarkably, the more degraded topsoil consistently displayed significantly higher average DOC concentrations than the subsoil, with 1.5 times greater levels at -60 hPa and 2.4 times higher at -600 hPa. This trend suggests that more degraded peat soils are prone to releasing higher amounts of DOC. Furthermore, in topsoil samples, DOC concentrations were consistently higher at the -600 hPa pressure head compared to -60 hPa. To enhance our understanding, we computed hydraulic conductivities at -60 and -600 hPa using Van Genuchten parameter values, subsequently estimating the DOC load under unit gradient conditions. This calculation is particularly relevant for real-field situations, especially in partially saturated (degraded) peat soils. The hydraulic conductivity at -600 hPa was nearly a hundred times lower than at -60 hPa, leading to the conclusion that macro-pores serve as the primary pathways for DOC release in peat soils, irrespective of higher DOC concentrations in the fine pore domain.
Modelling Ryder Glacier in Northern Greenland until 2100 under various emissions scenarios; Under which circumstances is the ice tongue lost?
Authors: Holmes Felicity , Barnett Jamie , Åkesson Henning , Nilsson Johan , Kirchner Nina , Jakobsson Martin
Published: March 2024

The Greenland Ice Sheet is currently the largest single contributor to global sea level rise, with recent decades having been characterised by an acceleration of mass loss. The Northern sector of the Greenland Ice Sheet has been relatively understudied, but is also the sector containing several of the last remaining ice tongues in Greenland. If these floating ice tongues are lost, the associated reduction in buttressing has the potential to lead to large increases in velocities and mass loss. One such glacier is Ryder glacier which, in contrast to the nearby Petermann glacier, has been reasonably stable in recent decades. As such, this glacier was targeted during the Ryder 2019 expedition with Swedish Icebreaker Oden, leading to a wealth of data on its present-day setting and Holocene history. In conjunction with this observational data, the numerical Ice Sheet and Sea Level System Model (ISSM) is used to investigate both the controls on glacier behaviour since 1900 and the likely trajectory of Ryder glacier towards 2100 under different emissions scenarios. The key focus is on understanding under which circumstances Ryder glacier may lose its ice tongue and what the impacts of this are likely to be in terms of glacier dynamics and sea level rise contribution.
Potential and limitation of remote sensing observations to monitor super coarse particles of ambient aerosol
Authors: Lopatin Anton , Dubovik Oleg , Sinuyk Alexander , Lind Elena , Lapyonok Tatyana , Eck Tom , Smirnov Alexander , Herreras Giralda Marcos , Momoi Masahiro , Litvinov Pavel , Perez Carlos
Published: March 2024

The potential presence of super coarse desert dust aerosol particles  with volume radii larger than 15 microns in the atmosphere has recently become one of hot topics intensively discussed in the modeling and observation community. Such large particles may represent an essential part of aerosol mass in the atmosphere and while their contribution to atmospheric radiation is rather moderate. Therefore, the characterization of super coarse aerosols is very challenging while they are responsible for sizable overall contributions in aerosol effects environment and climate dynamics. Indeed, AERONET network, that arguably can be considered as the most comprehensive source of information about ambient columnar aerosol properties does not consider aerosol particles with radius larger  than 15 microns. In contrast, most chemical transport models do consider super course particles and a number of in situ campaigns have reported the presence of such particles. This presentation describes efforts to test and evaluate the capabilities and limitations of detecting the super coarse dust particles from AERONET like measurements. It also considers possibilities to detect such particles using other remote sensing methods including lidar active observation and measurements in IR spectral range. Several modifications of the retrieval approaches that allow for optimizing remote sensing of super coarse ambient aerosol are proposed and discussed.
Chemical Analysis of Organic Matter in Cloudwater and Aerosol in High-Altitude Alps
Authors: Notø Hanne , Kasper-Giebl Anne , Kirchsteiger Bernadette , Kau Daniela , Happenhofer Felix , Riedelberger Thomas , Ludewig Elke , Holzinger Rupert
Published: March 2024

Organic matter in ice cores holds important climatic information, such as the prevalence of wildfires, marine algae blooms, terrestrial biosphere productivity, and antarctic sea ice extent. While organic compounds are specific tracers of the biosphere in paleoclimatic records, very little is known about their transport and deposition onto glaciers and ice sheets. Factors such as atmospheric transport, scavenging in the atmosphere and deposition efficiency can have a substantial effect on the amount of organic matter measured in the snow and ice. To better understand the deposition of organic matter onto glaciers and ice sheets, we determined the presence of organic species in clouds versus particulate matter in the atmosphere.  In this work we present data from a sampling campaign aimed at measuring organic matter in cloudwater and aerosol particles (PM1 and PM10). Samples were collected at the Sonnblick Observatory in the Austrian Alps (3106 m a.s.l.) across 10 days in November 2022. This site represents remote alpine atmospheric conditions. The samples were analyzed using a Thermal Desorption - Proton Transfer Reaction - Mass Spectrometer (TD-PTR-MS), which quantifies volatile and semi-volatile organic species. Further processing will reveal potential differences in organic composition between cloudwater and aerosol particles. This information can provide insight into the deposition of organic matter in the cryosphere, which affects the way ice core records are interpreted. 
Identifying sediment-discharge event types with a data-based clustering approach
Authors: Skålevåg Amalie , Korup Oliver , Bronstert Axel
Published: March 2024

Suspended sediment poses a risk to human and natural systems in terms of compromising water quality, flood hazard, hydropower production, and aquatic habitats. In many rivers the bulk of annual suspended sediment yield is mobilised and transported during (extreme) episodic runoff. Understanding such sediment-discharge events, including their drivers, may inform management strategies aimed at mitigating potential detrimental effects. Event-based analysis of local time series of suspended sediment transport has become a common approach to infer the dominant drivers and processes of sediment dynamics at the catchment scale. The increasing availability of detailed and continuous monitoring time series data enables us to use machine-learning techniques to identify groups of similar events, i.e. event types, and test whether and how these groups reflect similar catchment conditions and hydro-meteorological drivers. We present an approach which automatically detects, characterises and clusters sediment-discharge events. Hydrograph separation is used to automatically detect events, which are then filtered based on suspended sediment magnitude. The detected events are subsequently characterised with a selection of metrics, which are transformed into uncorrelated event characteristics with principal component analysis. Based on these characteristics events are clustered using a Gaussian mixture model. Finally, the identified event types are interpreted using catchment metrics describing antecedent conditions, hydrometeorological forcing, and catchment freezethaw state and snowcover.Applying our approach to a high alpine, glaciated catchment we find that the event regime in the catchment is mainly defined by event magnitude, hysteresis and event shape complexity. However, for the clustering suspended sediment and streamflow magnitude, and event shape complexity are the most important factors, whereas sediment discharge hysteresis is less relevant. The four identified event types are attributed to (1) compound rainfall-melt extremes, (2) glacier and seasonal snow melt, (3) freezethaw-modulated snow-melt and precipitation events, and (4) late season glacier melt. Our approach enables event-based analysis of riverine sediment fluxes, by detecting and grouping similar events together, which can in turn be interpreted to understand under which conditions episodic sediment fluxes occur in the target catchment.
GEMINI-UK: a new UK network of ground-based greenhouse gas observing spectrometers to help track progress towards net-zero targets
Authors: Humpage Neil , Palmer Paul , Feng Liang , Kurganskiy Alex , Woodwark Jerome , Doniki Stamatia , Ramsay Robbie , Boesch Hartmut
Published: March 2024

As part of the UK Greenhouse gas Emissions Measurement Modelling Advancement programme, the National Centre for Earth Observation are establishing the Greenhouse gas Emissions Monitoring network to Inform Net-zero Initiatives for the UK (GEMINI-UK). The primary aim of the GEMINI-UK network, comprising ten Bruker EM27/SUN shortwave infrared spectrometers, is to help quantify regional net GHG emissions across the UK, complementing in situ measurements collected by the existing tall tower network. Collectively, these data will eventually form the backbone of a pre-operational GHG emissions monitoring framework. The GEMINI-UK instruments observe column concentrations of carbon dioxide, methane, and carbon monoxide in cloud-free conditions, which we are using in the context of Bayesian inverse methods to constrain regional flux estimates of these gases. We have designed the measurement network to deliver the biggest error reductions in carbon dioxide flux estimates, working closely with host partners that include UK universities and schools and NERC facilities to promote the open access and transparency of the collected data. Continuous and autonomous operation of these instruments at each site is achieved by an automated weatherproof enclosure, based on a design developed by University of Edinburgh researchers, which previously enabled year-round measurements to be collected during the UK DARE-UK experiment in central London. In this presentation we describe the status and longer-term goals of GEMINI-UK, which is coming online through the first half of 2024, including an ongoing evaluation of EM27/SUN with a higher specification TCCON spectrometer at Harwell. We will also report data from the DARE-UK London deployment, which demonstrates the value in using all-weather enclosures and allows comparison with coincident measurements collected by the NASA OCO-2 and OCO-3 Earth orbiting instruments.
Understanding the dynamics of unsteady buoyant Jets: an experimental analogue of Vulcanian and Strombolian style eruptions
Authors: Hetherington Morgan , Cuthbertson Alan , Dawson Sue , Dioguardi Fabio
Published: March 2024

Explosive volcanic eruptions, which are characterized by the discharge of ash and gas from the vent into the atmosphere, are an example of a naturally occurring buoyant jet.  These buoyant jets can significantly impact the surrounding environment; for example, the presence of fine ash particles in the atmosphere can damage aircraft engines, potentially leading to engine failure. Therefore, during an explosive eruption, volcanic ash advisory centers (VAACs) consistently monitor the concentration of ash in the atmosphere using numerical models. These numerical models require the definition of a source term (i.e., source mass eruption rate, plume height and total grain size distribution), which is often obtained from simpler one-dimensional models. One-dimensional models derived from well-established theories successfully replicate the dynamics of the initial buoyant jet; however, they assume time-averaged source conditions which are not observed in field-scale vulcanian and strombolian style eruptions. As such, there is a disconnect between these well-established theories assuming time averaged source conditions and reality. This disconnect may introduce uncertainties in ash concentration forecasts, potentially resulting in practical implications such as unnecessary airspace closures or flights operating in hazardous conditions. The present contribution utilizes scaled laboratory experiments to quantify the influence of source variability on the dynamics of buoyant jets and evaluates potential deviations from time-average assumptions.Scaled laboratory experiments were conducted in an acrylic tank measuring 1200x670x450 mm, filled with water to a depth of 870 mm. A vertical pipe, 18 mm in diameter, was used to release fresh water (density ρ = 1000 kg/m³), which was combined with dye or particles, into saline water (ambient density  = 1000 - 1030 kg/m³). This configuration resulted in the generation of a vertical buoyant jet.  The flow rate was controlled and measured using a valve and ultrasonic flow meter. For the generation of unsteady discharges, a solenoid valve was employed, facilitating pulsed source conditions with discharge intervals ranging between ½ second to 2 seconds. Image analysis techniques, specifically light-induced fluorescence (LIF) and particle image velocimetry (PIV), were employed to measure buoyant jet characteristics, including concentration profiles, velocity fields, and jet geometry. These characteristics were measured under both steady and unsteady source conditions, facilitating a comparative analysis of the changes in behaviour arising from source condition variations.The experimental results were compared with integral assumptions of one-dimensional models. These findings will be presented, and their significance will be explored within the context of vulcanian and strombolian style eruptions.
Deep-time, planetary scale landscape evolution: Using the pre-industrial Earth as a calibration point for coupled tectonic, geomorphic and climate modelling on Earth and other planets.
Authors: Davies Hannah Sophia , Feulner Georg , Eberhard Julius , Bovy Benoit , Braun Jean
Published: March 2024

The field of Geomorphology covers the essential link between climate and geological processes such as tectonics. Because both of these processes operate on planetary scales, and over million year periods, landscape evolution models must, by necessity, do the same. With the advent of modern computing and the reduction in computational complexity of the Stream Power Law algorithm (SPL), it has become much easier to conduct investigations of landscape evolution on these scales. By doing so we can test model interactions between Earth system processes such as geodynamics, weathering, sediment flux, and erosion. In this work we aim to conduct landscape evolution modelling with the SPL algorithm on pre-industrial Earth, using high resolution climate models (CMIP – Coupled Model Intercomparison Project) and topographic maps with uplift histories as input. This model has already been used for planetary scale modelling on ancient Mars, and now we aim to use it to conduct a broad sensitivity analysis of the landscape evolution of pre-industrial Earth. We will compare the model outputs to established datasets and to other landscape evolution studies to best constrain the input parameters of the model (e.g., incision coefficient) to reproduce known water and sediment fluxes for the period. Once the model is calibrated, we aim to use it to look at periods of deep time where landscape evolution was perturbed by tectonic and climate excursions such as supercontinent assembly, and transitions to and from icehouse climate states. As with the pre-industrial study, this work would also include coupling to climate models but furthermore would be coupled to a global geodynamic model to produce topography, reducing reliance on paleo-topographical maps and allowing for comparison to previous studies that used those maps as topographic input.
The LUE open source software for building numerical simulation models on HPC
Authors: Karssenberg Derek , Schmitz Oliver , de Jong Kor
Published: March 2024

When developing large-scale numerical earth system models traditionally knowledge of a broad range of programming technologies is required to support hardware from laptops up to supercomputers. A knowledge that scientists specialized in a particular geosciences domain mostly do not have and often do not want to acquire. Their emphasis is on describing and implementing the processes rather than for instance dealing with parallelization of model equations. Moreover, when model characteristics or domain extents change their chosen parallelisation technique may already be obsolete or require significant refactoring to adapt to the new situation. We develop the open-source LUE modelling framework, a software environment allowing domain scientists – who may not be familiar with the development of high-performance applications – to develop numerical simulation models that seamlessly scale when adding additional hardware resources. LUE comprises of a data model for the storage of field-based and agent-based data, and provides a broad range of map algebra operations as building blocks for model construction. Each spatial operation is implemented in C++ using HPX, a library and runtime environment providing asynchronous execution of interdependent tasks on both shared-memory and distributed computing systems. LUE provides a Python module and therefore a single high-level API whether models are run on laptops or HPC systems. In our presentation we demonstrate two capabilities of LUE. First, using the built-in operations we implemented a spatially distributed hydrological model including surface water routing. The model runs for the African continent at 100 metres spatial and hourly temporal resolution. Secondly, to demonstrate the extensibility we utilise LUE’s focal operation framework to implement an individual kernel calculating greenness visibility exposure. Our PICO presentation will also include future extensions of the framework in particular for agent-based modelling and integration of machine learning model components.
Synchronized responses of lake and vegetation dynamics to climate change
Authors: Chen Shengqian , Su Yanan , Chen Fahu
Published: March 2024

Arid central Asia, the largest non-zonal arid zone globally, serves as a crucial region for the westerlies-dominated climate regime (WDCR). Despite observing a warm-wet trend in recent years, the response of surface landscape elements such as lakes and vegetation to this climate change remains uncertain. In this study, we conduct an analysis of long-term trends (1992-2020) in lake area and NDVI across arid central Asia while comparing them with key climate factors including precipitation, drought index, and soil moisture. Our findings reveal that lakes are expanding and vegetation is greening in most regions situated at elevations exceeding 100 meters. Conversely, lakes are shrinking and vegetation is browning solely in low-altitude areas (
A rapid numerical routine for viscoelastic earthquake cycle simulations. 
Authors: Sathiakumar Sharadha , Mallick Rishav
Published: March 2024

Earth’s largest quakes and trans-oceanic tsunamis emanate from subduction zones around the world. Following such large earthquakes, viscoelastic processes and on-fault aseismic fault slip play a crucial role in dissipating the stresses induced by the earthquake, facilitating the solid Earth's return to equilibrium.  The rheological properties of lithospheric rocks govern these postseismic processes and influence time-dependent deformation during the earthquake cycle. Geodetic observations offer an opportunity to constrain these rheological properties, providing valuable insights into the regional lithospheric structure, and potentially improving our understanding of earthquake-related hazards.   

To build intuition for geodetically recorded postseismic deformation, we develop a robust and efficient two-dimensional quasi-static periodic earthquake cycle simulator exploiting the boundary element method and semi-analytical solutions to systems of coupled ordinary differential equations. We investigate the impact of lateral and depth-dependent variations in the viscosity structure of the mantle wedge and the oceanic mantle, to discern their respective contributions and roles in surface deformation observations. We account for the long-term viscous flow rate in the mantle and show that neglecting this term in the earthquake cycle introduces biases in the effective viscosity structure of the lithosphere-asthenosphere system, particularly in the context of power-law rheologies. The low computational cost of our numerical routine makes it ideal for incorporating into future inverse modelling frameworks to estimate regional rheological structure from geodetic observations of subduction zone earthquake cycles.  
An attempt to calibrate a density-dependent groundwater flow model for a high energy subterranean estuary using particle swarm optimization and integrating salinity-, temperature- and 3H/He age observations 
Authors: Greskowiak Janek , Meyer Rena , Cueto Jairo , Skibbe Nico , Reckhardt Anja , Günther Thomas , Seibert Stephan , Schwalfenberg Kai , Pommerin Dietmar , Müller-Petke Mike , Massmann Gudrun
Published: March 2024

Subterranean estuaries below high-energy beaches are understudied, despite being potential powerful biogeochemical reactors at the land/sea transition zone affecting the quality of coastal waters. Highly transient hydro(geo)logical boundary conditions and density-effects lead to dynamic subsurface flow and transport patterns which are difficult to understand and hard to replicate by models. A comprehensive and unique 1-year dataset of hydraulic heads, salinity and temperature data in combination with apparent 3H/He ages was obtained at a beach research site on Spiekeroog Island in North Germany. The site includes 3 multilevel groundwater monitoring wells and a vertical electrode chain with 10 temperature sensors, all positioned on a transect aligned along the principal cross-shore flow direction and all reaching down to 24 m depth below ground surface. The data-set was used to set up and calibrate a site-specific groundwater flow and transport model, aiming to approximate the highly dynamic groundwater flow patterns on that transect. The simulation time needed to be 20 years because of the long model spin-up. Due to the complex and nonlinear nature of the system, model calibration was carried out via particle swarm optimization, which is superior to gradient-based optimization techniques with respect to finding a global minimum of the objective function. The calibration results were reasonable. The dynamics of hydraulic head data were well captured, however, simulated values were constantly higher than those observed. The observed salinities were best captured for the multilevel wells near the mean high water and low water line. At the highest multilevel well located at the upper beach right at the dune base, simulations matched observations less well. Similarly, groundwater temperatures and ages were best replicated at the location in the infiltration zone near the high-water line. Groundwater ages and their temporal dynamics at the dune base and mean low water line could only be replicated down to 12 m depth. Deviations between simulations and observations are likely due to 3D flow effects in longshore direction, which could not be captured with the 2D vertical cross-sectional model approach. However, long model run times hindered calibration of a full-blown 3D density-dependent, 20-year long-term groundwater flow and transport model. The next step is to estimating the importance of longshore hydraulic gradients. Finally, the model will be extended for hydrobiogeochemical reactions to assist in the analysis and understanding of the observed hydrochemical data at this site.                    
Sea bird foraging in a changing seascape
Authors: Wilmes Sophie-Berenice , Robins Peter , Harris Stephanie , Bishop Charles , Waggitt James , Fernandes Paul , Cordes Line
Published: March 2024

Sea birds in the Irish Sea are known to target tidal mixing fronts (the interfaces between seasonally stratified and mixed waters) as foraging grounds as these tend to be areas high in nutrients and primary productivity and thus, prey availability. However, little is known about the inter- and intraannual variability of the areas selected as foraging grounds by the sea birds. Here, using foraging locations derived from GPS tags on Manx shearwaters (Puffinus puffinus) and reanalysis oceanographic data and observational data collected from cruises, we evaluate which oceanographic features are targeted by the shearwaters on their foraging trips into the Irish Sea and how the characteristics of these frontal areas vary seasonally and interannually. Comparing a range of different physical measures to describe front locations, we show that the birds generally select interannually persistent marginally stratified (as defined by the potential energy anomaly) areas. Furthermore, we demonstrate that the features which are selected by the birds as foraging grounds vary over the course of summer months. Next, we use projections of future changes in shelf sea oceanography to highlight and discuss the consequences changing shelf sea stratification and physical features in the Irish Sea.
Current State of Coastal Subsidence in Europe Derived from the European Ground Motion Service
Authors: Thiéblemont Rémi , Le Cozannet Gonéri , Nicholls Robert J. , Rohmer Jérémy , Wöppelmann Guy , Raucoules Daniel , de Michele Marcello , Toimil Alexandra , Lincke Daniel
Published: March 2024

While the understanding and modelling of sea level rise (SLR) due to ocean density and mass changes have greatly improved over the past few decades, relative SLR contributions due to vertical land motions (VLMs) remain a major source of uncertainty. It is critical to downscale global and regional sea-level rise to local relative sea-level change as this is what causes coastal impacts and adaptation needs. In particular, land subsidence can strongly exacerbate coastal flood risk, saltwater intrusion, erosion and loss of wetlands and damage to infrastructure.Here, we present the first analysis of pan-European coastal subsidence based on the European Ground Motion Service (EGMS) Ortho product. First, we perform a comparison between EGMS Ortho (Level 3) vertical velocity estimates and GNSS stations vertical velocity. This comparison reveals that the geodetic reference frame used to calibrate EGMS affects the vertical land velocity estimates and needs to be accounted for carefully, especially for the vertical land motions – including sub-millimetric/year velocities – that could affect local SLR estimates. After adjusting the EGMS calibrated product to the International Terrestrial Reference Frame (ITRF2014), we performed an assessment of VLM in European coastal flood plains. Our results show that half of the European area located in coastal flood plain is, on average, experiencing subsidence at a rate stronger than -1 mm/yr. More importantly, we find that urban area and population experience almost a -1 mm/yr subsidence on average (if we discard the uplifting regions due to Glacial Isostatic Adjustment) and for coastal airports and for harbours, the average land motion drops is even larger with -1.5 mm/yr subsidence rate. Finally, while our analysis allows identifying already well-known coastal subsidence hot-spots (e.g. Northern Italian coastal plain, Netherlands), we demonstrate with few examples that EGMS analysis also paves the way toward the identification of subsiding local scale coastal zones that have been ignored so far and for which flooding risk may become a major concern.
The role of understory vegetation in surface fluxes of carbonyl sulfide in a boreal forest
Authors: Maseyk Kadmiel , Sun Wu , Seibt Ulli , Kooijmans Linda , Chen Huilin , Kohonen Kukka-Maaria , Kolari Pasi , Alto Juho , Mammarella Ivan , Vesala Timo
Published: March 2024

The parallel uptake of carbonyl sulfide (COS) with CO2 during photosynthesis provides an opportunity to constrain gross photosynthesis at ecosystem and larger scales. To use COS for this purpose we need to understand the scaling factor between COS and CO2 fluxes (the leaf or ecosystem relative uptake ratio) and the influence of other COS sinks or sources. This information is obtained from chamber measurements and ecosystem flux measurements, and in the case of uptake ratios tends to be focussed on the dominant canopy layer. However, in many ecosystems the understory vegetation is an important component of the overall productivity, and experiences microclimate conditions different from the canopy that can influence the uptake ratios. Where the vegetation is close to or appressed to the soil surface provides an interesting case, as it can reduce soil COS uptake or mitigate soil COS release. We measured soil and forest floor COS, CO2, and CO fluxes in a boreal forest (Hyytiälä, Finland) with a surface vegetation layer of moss and dwarf shrubs (Vaccinium species) using chambers, alongside ecosystem fluxes by eddy covariance, through a growing season (April – November 2016). COS fluxes from moss-covered surfaces did not differ appreciably from bare-soil fluxes, but COS uptake was approximately twice as high where vascular vegetation was present. The vegetated surfaces were a net source of CO2 through the season due to soil respiration exceeding photosynthesis, but diurnal patterns show a clear influence of the vegetation on CO2 fluxes. COS:CO2 flux ratios were consequently lower from the vegetated surface compared to soil (or moss covered soil) but decreased with temperature in the same manner as soil flux ratios. A first estimate of the surface vegetation fluxes indicate they make up about 15% of the ecosystem COS flux, and therefore understanding the magnitude and behaviour of understory COS fluxes is important as we develop our understanding of the relationship between COS and CO2 for large scale photosynthesis estimates.
Chemical composition and morphological analysis of two-layered attic dust samples from a former industrial area (Ózd city, Hungary): insights into historical environmental contamination
Authors: Maghsoudlou Mona , Tserendorj Davaakhuu , Abbaszade Gorkhmaz , Salazar Nelson , Völgyesi Péter , Szabó Csaba
Published: March 2024

Studying the chemical composition and physical properties of undisturbed attic dust provides valuable insights into historical environmental contamination, indicating the impact of various anthropogenic and natural sources on long-term air pollution in urban environments. Ózd, a former industrial city in Hungary, played a significant role for iron and steel works between 1835 and 1990, operated iron and steel factory in the city center. As a consequence of the collapse of the old political and economic system, the industrial structure of the city was restructured in the early 1990s. We collected attic dust samples from a building within the territory of former iron factory which is operating as a small horsebox factory during the past ~25 years. Distinct stratum was observed during sample collection, resulting in the identification of two layers: the upper layer and the lower layers, characterized by different color appearances and amounts of dust.In this study, we analyzed bulk samples to determine their elemental compositions, such as major, and trace elements including the rare earth and high field-strength elements (REE+Y and HFSE). The elemental contents of attic dust samples were analyzed using quadrupole-based ICP-MS after aqua regia digestion. Scanning electron microscope (SEM) was used to determine morphological properties, chemical composition, shape, and size of attic dust particles. The major elements, such as Ca, Mg, Na, K, and S, are at least two times higher in the lower layer, whereas Al and Fe showed the same concentrations in both layers, pointing on potential historical industrial influences on environmental contamination. Among the trace elements, Ti, Cr and Mn concentration show higher, whereas V, Co, and Ni concentrations show lower values than those in the upper layer. Metal(oid)s like W, Mo, Ag, Cd, Hg, Pb, and Bi have higher concentrations in the lower layer compared to those of Cu, Zn, Sn, and Sb, whereas the As concentration was the same in the two layers. In contrast, HFS and REE+Y showed highly unusual patterns for both layers. SEM (scanning electron microscope) image analyses highlighted the prevalence of highly oxidized particles, particularly iron oxides, predominantly observed in the upper layer. By establishing a relation between the two attic dust layers, notable differences in elemental composition became evident highlighting the impact of past industrial activities on the environmental pollutants, making a shift in the amount and type of chemical composition after the shutdown of the system. 
Taking stock of the global area boom for greenhouse cultivation in the 21st century
Authors: Tong Xiaoye , Zhang Xiaoxin , Fensholt Rasmus , Rosendal Dau Jansen Peter , Li Sizhuo , Nylandsted Larsen Marianne , Reiner Florian , Tian Feng , Brandt Martin
Published: March 2024

Greenhouse cultivation that favors agricultural productivity is booming globally in the past decades. Yet, currently little knowledge exists on its global extent and possible drivers of the expansion. Here, we present a global assessment of greenhouse cultivation and map 1.3 million hectares of greenhouse infrastructures in 2019, including both large (61%) and small scale (39%) greenhouse infrastructure that are optimally detectable by using commercial satellite data at 3 m resolution. Examining the temporal development of the 65 largest clusters (> 1500 ha), we show a recent upsurge in greenhouse cultivation in the Global South since 2000s, primarily aimed at enhancing agricultural productivity and achieving economic prosperity. China is leading the boom in the Global South and accounts for 61% of the global greenhouse cultivation. Trade and production data for five major greenhouse-cultivated vegetables suggest that China's greenhouse cultivation boom is primarily driven by domestic mechanisms, rather than international ones. To investigate this hypothesis, we examined the spatial patterns of greenhouse cultivation in China and found distinct configurations around urban areas for food provision and around rural areas for poverty alleviation. Our high-resolution thematic map serves as a global baseline for future exploration of environmental and socioeconomic factors related to greenhouse cultivation. Our study also underscores the need for sub-category reporting and optimizing international policies to address measurement, reporting, and verification of greenhouse cultivation.
Climate change in the alps: Comparing different climate models based on estimates of monthly data.
Authors: Hasel Kristofer , Bügelmayer-Blaschek Marianne , Formayer Herbert
Published: March 2024

The new generation of global climate models (GCM) CMIP6 show significantly higher climate sensitivity then their predecessors (Zelinka 2020), introducing faster temperature rise than expected. Especially mountainous regions are sensitive to climate change resulting in higher frequency of extreme weather events (Gobiet 2014).  Unfortunately, global climate models are too coarse to deliver reliable data in complex terrain, making it difficult to estimate regional effects of climate change.  Climate indicators like maximum precipitation in one day or heat days are a profound way to investigate climate change, not only in its means, but also in its extremes. These indicators are often peak-over-threshold indicators which need daily and bias adjusted data to be calculated from. But there are valuable data sets like HISTALP which reach back until the year 1750 consisting solely of monthly frequency. We compare two generations of GCMs (CMIP6 vs CMP5) to understand their systematic differences and how these differences affect the climate indices in the models global warming levels (GWL). Furthermore, we try to analyse the differences in precipitation trends and if these interact with the trends in extreme temperatures. To be able to compare the data with mentioned HISTALP dataset, we calculate the indices from monthly data using the method presented in Hasel et. al. 2023. The method consists of a linear regression model connecting monthly meteorological parameters with their respective climate index. Trained by ERA5 Land data, which is supplemented by a CMIP6 global climate model, it also allows to capture the effects of climate change. Additionally, it contains a simple bias adjustment and regrids the data to ERA5 Land’s 0.1° grid.
 
References
Zelinka, M. D., Myers, T. A., McCoy, D. T., Po‐Chedley, S., Caldwell, P. M., Ceppi, P., ... & Taylor, K. E. (2020). Causes of higher climate sensitivity in CMIP6 models. Geophysical Research Letters, 47(1), e2019GL085782.
Hasel, K., Bügelmayer-Blaschek, M., & Formayer, H. (2023). A statistical approach on estimations of climate change indices by monthly instead of daily data. Atmosphere, 14(11), 1634.
Gobiet, A., Kotlarski, S., Beniston, M., Heinrich, G., Rajczak, J., & Stoffel, M. (2014). 21st century climate change in the European Alps—A review. Science of the total environment, 493, 1138-1151.