bluuebunny/crossref_metadata_2025 huggingface dataset:
Wave flume experiments to unravel saltmarsh cliff hydrodynamics
Authors: Muller Jos , Borsje Bas , van der Werf Jebbe , Dermentzoglou Dimitrios , Hofland Bas , Hulscher Suzanne , Antonini Alessandro
Published: February 2023

Nature-based flood defences receive increasing interest as a viable option for improving flood safety worldwide. A contemporary case is using the ability of saltmarshes to attenuate waves during storm conditions for strengthening coastal flood defences. To ensure a long-term reinforcement of flood protection, it is important to understand the erosion mechanisms of saltmarshes during storms. One of the critical locations for erosion is at the transition between the saltmarsh and the bare mudflat, often characterized by a vertical step or cliff. These cliffs vary between 0.2 to 2.0 m in height, depending on soil composition and local hydrodynamics. However, wave-induced hydrodynamics that controls the (mass) erosion at the saltmarsh cliff are not fully understood. Also the role of saltmarsh vegetation on these near-cliff hydrodynamics are not clearly quantified. In this research, a series of wave flume experiments are performed in a 40 m long, 0.8 m wide and 1.0 m deep wave flume. Generated waves traverse over a saltmarsh transect, consisting of 5 m foreshore section with a slope of 1:45, a varying cliff height to a maximum of 0.2 m, 7 m saltmarsh section and dike section with a slope of 1:3. The experiments are designed according to Froude scale of 1:10. Vegetation is modelled by elastic cylinders, scaled according to Cauchy similitude. Offshore irregular wave height will range between 0.1 and 0.2 m at a water depth varying between 0.3 and 0.6 m, while nearshore (at the saltmarsh) waves are mainly depth limited. Water levels are measured by several wave gauges and laser scanners. Wave-induced pressures at the saltmarsh cliff are measured by pressure transducers mounted around the cliff. Particle Image Velocimetry is used to quantify near-cliff velocities patterns in a non-intrusive way and validated with additional velocity measurements. Quantification of the wave-induced hydrodynamics and its dependency on vegetation will result in a valuable dataset for model development and validation, and will help in understanding erosion mechanisms at a saltmarsh cliff during storm events.
Coupled climate-carbon simulations of the Penultimate Deglaciation and Last Interglacial in the PLASIM-GENIE model
Authors: Cutler Tim , Holden Philip , Anand Pallavi , Edwards Neil
Published: February 2023

Theoretical understanding of paleoclimate change such as deglaciations comes primarily from time slice simulations in state-of-the-art atmosphere-ocean general circulation models, where multimillennial transient simulations would be too computationally expensive. Such steady state runs may be missing long-timescale processes involving ocean circulation or the carbon cycle, which could be captured by long transient simulations. The PLASIM-GENIE (Planet Simulator – Grid-Enabled Integrated Earth System) model is capable of running fast, multimillennial climate-carbon cycle simulations, comprising a fully 3D spectral atmosphere and frictional geostrophic ocean with marine and terrestrial carbon cycle modules. Here, we present comparisons between steady state and pseudo-transient experiments in PLASIM-GENIE, starting from the Penultimate Glacial Maximum (140,000 years before present) through the Last Interglacial, applying the PMIP4 Penultimate Deglaciation protocol. In pseudo-transient simulations, the model is stopped at every 500 years and restarted with updated prescribed ice sheets, orbital forcings, meltwater fluxes and relaxed CO2 (with an active carbon cycle). These are compared to steady state time-slice simulations where the model is spun-up at each 500-year interval, to test for hysteresis in atmosphere, ocean and carbon cycle processes. Particular focus is on the timing of Atlantic Meridional Overturning Circulation weakening and recovery. We supplement these baseline simulations with a series of sensitivity experiments where individual forcings are varied.
Searching for the bomb spike in Danube river sediments: Extracting the anthropogenic impact of Vienna
Authors: Hatzenbühler Diana , Weißl Michael , Baumgartner Christian , Wagreich Michael
Published: February 2023

The Anthropocene, the strongly debated potential new unit of the Geological Time Scale, describes the intensified anthropogenic influence on the environment and geological processes, and its traces in geological archives. Regional studies characterizing the growth of human impact, the Anthropocene transformation, are scarce, especially for urban or per-urban environments.In this project, we investigate the anthropogenic impact of the metropolis Vienna on its peri-urban environment and the proposed beginning of the Anthropocene epoch in the 1950s CE by applying sedimentological and geochemical methods. In previous studies (Wagreich et al. 2022), the authors were able to successfully detect the human influence in urban sedimentary archives of Vienna (anthropogenic coarse sediments) using artificial isotopes and anthropogenic trace metals. For our project, we extend the study area from Vienna to the city of Hainburg to investigate Vienna’s anthropogenic impact in both anthropogenic and natural sediments downstream the Danube river. In this area, direct human intervention in the environment, such as ground excavations, backfill and damming, is highly variable, from locally strong (e.g., hydro-power dams, airport constructions), to not existing (National Park Donau-Auen), thus offering a suitable location to trace and quantify the extent of anthropogenic impact.Within petrographic facies, sedimentological and geochemical markers are applied to characterize the anthropogenic strata in this area: The archive of fine-grained natural Danube deposits, i.e. erosional profiles and sediment cores, is analysed for trace metals, artificial radiogenic isotopes, and microplastics with the aim (i) to disentangle the anthropogenic fingerprint of Vienna from the sediment, (ii) to identify and evaluate the proposed Anthropocene geological boundary around 1950 CE, and (iii) to evaluate a potential correlative stratigraphic reference section section/ point for the Anthropocene downstream of Vienna. Finally, the Carnuntum-Vienna Anthropocene field lab offers the opportunity to integrate environmental systems modelling with an Anthropocene equation approach for the temporal and spatial growth of the anthropogenic layers (iv).           
Improved data-driven ecosystem carbon fluxes under moisture stress through synergistic Earth observations
Authors: Walther Sophia , Nelson Jacob A. , Migliavacca Mirco , Dorigo Wouter A. , Ermida Sofia L. , Duveiller Gregory , Gans Fabian , Ghent Darren , Kraft Basil , Veal Karen L. , Weber Ulrich , Zotta Ruxandra-Maria , Jung Martin
Published: February 2023

The integration of global land surface remote sensing and in situ measured ecosystem carbon fluxes through machine learning approaches offers a unique data-driven perspective to diagnose the carbon cycle. Earth Observation (EO) data sets from different parts of the electromagnetic spectrum contain specific information on the land surface status, but also on the structural and physiological vegetation conditions. Each EO-derived land surface variable alone has a limited scope, addresses only individual aspects of the complex system, and can be confounded by other factors.  Here we use the new generation statistical flux upscaling framework Fluxcom-X to analyse the individual and synergistic contributions of different EO data sets to site-level terrestrial carbon fluxes in tailored cross-validation experiments. Several distinct data streams are explored as predictor variables:  land surface temperature (LST) from both polar orbiters and geostationary satellites (MODIS and SEVIRI), far-red SIF from GOME2, multi-spectral vegetation optical depth (VOD) from different sources (ku-band climate archive from Moesinger et al.(2020) and L-band from SMOS), and soil moisture (SM) from ESA CCI.  Each predictor variable undergoes a dedicated pre-processing in terms of quality checks and gap-filling. Beyond their overall added value in prediction skill, we are interested in the impacts of the EO predictors on different scales of carbon flux variability (e.g. diurnal, seasonal, seasonal anomalies, inter-annual, and between sites), specifically during situations of unusual water scarcity and surplus. We also compute SHAP values to understand how the machine learning model uses the EO information. Additionally, a second line of analysis addresses the role of acquisition properties for the accuracy of the estimates.The first results for the predictor variable MODIS LST show that the inclusion of MODIS LST improves GPP estimates on all time scales.  The model strongly profits from LST as surrogate for moisture availability during dry anomalies, and for light availability during wet anomalies. Regarding the impact of acquisition properties of MODIS, we find that the variability in viewing geometry and overpass time does not affect the accuracy of simulated site-level GPP. However, failing to account for the clear-sky bias in availability of MODIS LST will result in a substantial decrease in accuracy, especially for overcast days.Further experiments will include SEVIRI LST, SIF, VOD, as well as soil moisture, and we will analyse their role in the data-driven simulations of carbon fluxes. The lessons learned from the site-level cross-validation experiments will guide the production of gridded estimates of gross and net carbon fluxes for Europe and the globe.
Assessing and monitoring urban landslide hazards - integrating geophysics, remote sensing, and wireless sensor networks
Authors: Uhlemann Sebastian , Fiolleau Sylvain , Wielandt Stijn , Dafflon Baptiste
Published: February 2023

Growing urbanization is pushing communities further into areas of known landslide hazard, elevating the risk posed to these communities. Hence, there is an increasing need to develop approaches that can characterize and monitor landslide hazards in urban areas. Here, we present recent developments in the rapid characterization of the landslide hazard using geophysics and remote sensing to parametrize hydromechanical models to assess probability of failure across a site in the highly populated Berkeley Hills, California. Calculating slope gradient from LiDAR, and estimating soil thickness from ambient seismic noise measurements, and total cohesion from vegetation distribution, we include the spatial variability of some of the most critical soil parameters in our hazard assessment. The results highlight various areas of elevated landslide hazard. Focusing on one such area, we used geophysical monitoring data to link changes in subsurface properties with slope instabilities, and found that rainfall induced increases in pore pressure drive slope deformation. Changes in seismic properties occurred up to 5h before actual soil displacements commenced. To monitor the hazard across the entire study site and to further increase our understanding of their triggering factors, we developed and  installed a dense wireless network of deformation, soil moisture, and pore pressure sensors. Using machine learning, we use this data to predict subsurface conditions critical to slope failure. We show that short-term predictions are comparably accurate, while long-term forecasts fail to predict sudden changes, mostly due to a lack of training data. The data obtained from these studies is starting to be incorporated into site management with the aim of mitigating the landslide risk. 
Vegetation changes following forest disturbance affect soil carbon and nitrogen cycles through microbial communities
Authors: Mayer Mathias , Hechenblaikner Florian , Rosinger Christoph , Stierli Beat , Frey Beat , Hagedorn Frank
Published: February 2023

Increasing forest disturbance is among the most profound impacts of climate change on terrestrial ecosystems. Insect outbreaks, storms, or wildfires can destroy the whole tree layer, with serious consequences for biogeochemical cycles until succession returns the ecosystem back to a forested state. However, tree regeneration is often inhibited by ungulate herbivory and herbaceous competition, and disturbed ecosystems remain in non-forested states for decades. The impact of such vegetation changes on soil carbon (C) and nitrogen (N) cycles is highly unknown, because a multitude of plant-soil feedbacks are involved, and underlying processes have hardly been investigated. Here, we studied soil microbial community structure, gene abundance of bacteria, fungi, and N cycling microorganisms, soil enzymes, and C-N dynamics across a disturbed forest landscape in Central Europe, covering a range of successional stages after storm damage and bark-beetle attacks. We used a chronosequence-approach including disturbed sites regrown with Picea abies stands, and disturbed sites dominated by herbaceous pioneer plants, particularly Calamagrostis grasses. Soil C and N stocks increased under a prolonged herbaceous cover. Three decades after disturbance the stocks were ca. 45% higher than those of regrown forest stands. Beside C inputs from herbaceous fine roots, we link this increase to changes in the structure and functioning of the microbial community, which reduces the decomposition of organic matter. With a prolonged herbaceous cover, decreasing fungal abundances coincided with declining activities of phenol oxidase and of hydrolytic enzymes used to acquire nutrients. Since ectomycorrhizal fungi were almost absent compared to regrowing forest stands, this may be linked to reduced ectomycorrhizal mining for organic N. Moreover, ammonia-oxidising (amoA) gene abundances increased along with ammonium and nitrate concentrations, pointing towards an accelerated inorganic N cycle under a prolonged herbaceous cover. A surplus of inorganic N and grass-rhizodeposits renders it also likely that saprotrophs are less dependent on organic matter-bound C and N. Taken together, we found strong evidence for a linkage between above- and belowground communities following forest disturbance. We suggest a prolonged cover of herbaceous pioneer plants opens the nitrogen cycle through microbial communities which reduces mining for organic N and thus, increases soil C storage.
Testing new indicators for ecological resilience in a dryland mountain ecosystem using a multidecadal NDVI time-series
Authors: Vermeer Angelique , Garcia Mayor Ángeles , Förster Saskia
Published: February 2023

In this work, the ecological resilience to drought of a dryland catchment in the Moroccan High Atlas Mountains was studied. A time-series of Landsat NDVI data between 1984 and 2019 was used to determine areas of overall greening and browning. The Breaks For Additive Seasonal and Trend (BFAST) change detection methodology was used to determine breakpoints and trends in the time-series. The breakpoints were classified using a newly developed typology based on the trend before and after the breakpoint. The improved typology that is introduced, considers the statistical significance of trends, and subdivides them in categories of abrupt changes that lead to an improvement of ecosystem functioning (positive breakpoints) and abrupt changes that lead to a deterioration of ecosystem functioning (negative breakpoints). The ecological resilience in the catchment was explored using the number, sign and typology of the breakpoints detected and their relation to the various land uses and climatic zones of the catchment. In general, a small amount of change in NDVI between 1984 and 2019 was observed in the whole catchment. However, there was a large spatial variability in the number and type of breakpoints, pointing to the additional information provided by these indicators, which will be discussed in our presentation.
Microplastic monitoring and data quality assessment for effective model error evaluation
Authors: Murawski Jens , She Jun , Frishfelds Vilnis
Published: February 2023

The assessment of microplastic pollution in the marine environment is a requirement for the evaluation of the present situation and development of efficient combatting strategies. In combination with model based transport assessments, the monitoring of microplastics provides a tool for the assessment of the overall budget for the entire Baltic Sea and sub-basins. Furthermore, monitoring data sets can be used to evaluate the model performance in capturing spatial and seasonal pattern of marine pollution. Currently, the scope of microplastic monitoring is quite limited, which is why it is an important issue to control the quality of the available datasets and to derive useful indicators from the available data. Our study of single source data sets, with improved error statistics compared to multi source data sets, shows that the mean sampling error is still relatively high, about 40%–56%, which has been estimated using replicate samples. The lack of surface flow correction when using mantra net or trawl methods introduces and additional 12% uncertainty. When compared to model data, additional uncertainties come into play, related to the model characterization of microplastics as a set of spherical particles with a given density and diameter, which differs fundamentally from the broad range of values occurring in nature. It is therefore important to derive useful indicators from the measured and monitored data sets before attempting to validate the model. In our presentation, we will detail the assessment of sampling errors and provide an overview over the extent of microplastic monitoring assessed in the CLAIM project for the Baltic Sea. The collected data set was used to evaluate the quality of DMI’s microplastic transport model in reproducing spatial and seasonal patterns. The database of the model-observation assessment covers the 6 years period 2014-2019, with regular monitoring data sets in the eastern Baltic Sea being available since 2016. Finally, we discuss recommendations that could help to reduce sampling errors and derive indicators that are useful for a quality assessment of microplastic models. Aim is the development of operational modelling and monitoring capabilities for marine microplastic pollution.  
Relatively relocated seismicity during the 2021 Fagradalsfjall dyke intrusion, Reykjanes Peninsula, Iceland: Detailed evolution of a lateral dyke, and comparison to Bárðarbunga-Holuhraun
Authors: Glastonbury-Southern Esme , Winder Tom , Greenfield Tim , Ágústsdóttir Thorbjörg , Rawlinson Nick , White Robert , Brandsdóttir Bryndís , Fischer Tomas , Horálek Josef , Doubravová Jana , Bacon Conor , Gudnason Egill Árni , Hersir Gylfi Páll , Hrubcova Pavla , Eibl Eva P. S.
Published: February 2023

The 2021 Fagradalsfjall eruption on Iceland’s Reykjanes Peninsula was preceded by more than 12 months of elevated seismic and inflationary activity, beginning around December 2019. On 24th February 2021, an exceptionally intense episode of seismicity covering the length of the Peninsula marked the initiation of a dyke intrusion, which continued to develop until the 19th of March 2021, when melt first erupted at the surface. During the intrusion, more than 80,000 microearthquakes marked the propagation of melt, first northeast towards Mt Keilir, then to the southwest, eventually forming a 10 km-long dyke. These events were recorded by a dense local seismic network and detected and located using QuakeMigrate[1].We present relative relocations of the seismicity, and tightly constrained focal mechanisms for earthquakes from the dyke intrusion period. The high precision of the relative relocations reveals fine scale structure in the region, which is studied in relation to the orientation of fault planes rupturing in individual earthquakes, thus providing insight into the mechanism of dyke propagation and the controls on faulting in the region. We find that the strikes of the fault planes of individual earthquakes differ from the overall trend of dyke propagation across several propagating seismic swarms.We compare our findings for the Fagradalsfjall seismicity to the 2014-2015 Bárðarbunga-Holuhraun intrusion and eruption seismicity [2], in the context of the contrasting tectonic settings, and markedly different precursory activity.1: Tom Winder, Conor Bacon, Jonathan D. Smith, Thomas S. Hudson, Julian Drew, & Robert S. White. (2021). QuakeMigrate v1.0.0 (v1.0.0). Zenodo. https://doi.org/10.5281/zenodo.44427492: Woods, J., Winder, T., White, R. S., and Brandsdóttir, B., 2019. Evolution of a lateral dike intrusion revealed by relatively-relocated dike-induced earthquakes: The 2014–15 Bárðarbunga–Holuhraun rifting event, Iceland. https://doi.org/10.1016/j.epsl.2018.10.032
Assessing the quality of the Sentinel-5p TROPOMI cloud products and their reprocessing using ground-based Cloudnet data
Authors: Compernolle Steven , Argyrouli Athina , Lutz Ronny , Sneep Maarten , Lambert Jean-Christopher , Fjaeraa Ann Mari , Granville José , Hubert Daan , Keppens Arno , Loyola Diego , O'Connor Ewan , Pinardi Gaia , Rasson Olivier , Romahn Fabian , Stammes Piet , Verhoelst Tijl , Wang Ping
Published: February 2023

The retrieval of atmospheric composition from space-based measurements, by e.g., Sentinel-5p TROPOMI, is strongly affected by radiative interferences with clouds. Dedicated cloud data products, typically retrieved from measurements by the same sounder, are therefore essential. Cloud information is used to filter data and as input to the modelling of atmospheric radiative transfer and the conversion of slant column densities into vertical column densities.
The three main TROPOMI cloud retrieval algorithms are: (i) L2_CLOUD OCRA/ROCINN CAL (Optical Cloud Recognition Algorithm/Retrieval of Cloud Information using Neural Networks; Clouds-As-Layers), (ii) L2_CLOUD OCRA/ROCINN CRB (Clouds-as Reflecting Boundaries), and (iii) the S5P support product FRESCO-S (Fast Retrieval Scheme for Clouds from Oxygen absorption bands for Sentinel). The cloud variables provided by these products (radiometric cloud fraction, cloud (top) height, and cloud albedo/cloud optical thickness) are subsequently used in the retrieval of the TROPOMI trace gas products. The quality of cloud products and trace gas products is routinely assessed by the ESA/Copernicus Atmospheric Mission Performance Cluster (ATM-MPC) validation service, with ad hoc support from Sentinel-5p Validation Team (S5PVT) AO projects.
Version upgrades have had a significant impact on the characteristics of S5P cloud data. The change of the wavelength window in the FRESCO product since version 1.4 (‘FRESCO-wide’) leads to a clear increase in the height of low clouds with a large impact on the tropospheric NO2 retrieval (van Geffen, 2022), and improving the validation results regarding the tropospheric and total NO2 column. The first upgrades of the ROCINN products (from v1 to v2.1-v2.3) led to an increase in correlation with CLOUDNET cloud height, but to a more negative bias for the low clouds, with ROCINN CRB cloud height even dropping below the CLOUDNET cloud base height on average. However, this effect seems alleviated with the latest upgrade to v2.4. The impact on the HCHO validation results is investigated but is less clear compared to the NO2 case.
To resolve the discontinuities due to the processor version jumps, a full mission reprocessing is currently ongoing and largely carried out for the L2_CLOUD and FRESCO-S products. The reprocessed ROCINN data have a lower dispersion and higher correlation with respect to the CLOUDNET cloud heights. The bias of the L2_CLOUD OCRA/ROCINN CAL CTH becomes more negative, but that of L2_CLOUD OCRA/ROCINN CRB CH bias improves. Finally, we also discuss the impact of the FRESCO-S reprocessing on the validation results.
The abundance of plunging flows in bedrock rivers
Authors: Hurson Max , Venditti Jeremy , Rennie Colin , Church Michael
Published: February 2023

Bedrock rivers are the keystone to understanding landscape evolution as they control the rate of geomorphic responses to climatic and tectonic signals. Bedrock erosion is driven by channel hydraulics, which are not well understood for complex bedrock river morphologies. Some bedrock rivers exhibit a constriction-pool-widening morphology and associated plunging flow where the core of maximum velocity follows the bed into deep pools. Previous observations suggest that moderate discharges enhance the erosive potential of plunging flows, and that plunging flows are the dominant driver of morphology and downcutting in reaches where they are present. However, there are very few observations of plunging flows in natural environments, so their frequency and cumulative impact on landscape evolution is still unclear. Here we examine Acoustic Doppler Current Profiler and Multibeam Echosounder data collected in the Fraser Canyon of British Columbia, Canada to better understand the general properties and frequency of plunging flows. The entire 375 kms of the Fraser Canyon were analyzed for indicators of plunging flows to estimate their frequency. Results suggest that plunging flows appear to be abundant and are correlated with high shear stresses which are concentrated into deep bedrock pools. When examined using common erosion modelling techniques, observations suggest that reaches with plunging flows are incising at a much faster rate than non-plunging reaches. This work shows that considering reach scale hydraulics is critical for understanding the morphogenesis of large bedrock rivers and the mountainous landscapes that they drain. The abundance of plunging flows in large bedrock rivers suggests the importance of integrating complex flow patterns into bedrock erosion models, informs patterns of bedrock erosion at the reach scale, and begs for further investigation into the distribution of fluid shear stresses in complex bedrock channel morphologies.
A linearized approach to study stability and waveguidability of barotropic Rossby waves
Authors: Segalini Antonio , Riboldi Jacopo , Wirth Volkmar , Messori Gabriele
Published: February 2023

The propagation and the characteristics of Rossby waves are influenced by the large-scale background flow where they occur: for instance, the role of upper-level jet streams in promoting Rossby wave propagation along preferred directions (so-called “waveguidability”) is a classic problem in climate dynamics. We propose a linear framework to study barotropic Rossby waves over a spherical domain for arbitrary orographic forcing and zonal background flow configurations, including cases with localised single and double jet streams. The approach allows to analytically obtain the steady-state linear flow response to orographic forcing without performing lengthy numerical integrations, together with the flow evolution as a combination of few modes composed by the various eigensolutions of the unforced problem (thus independent of the forcing). The connection between jet strength and waveguidability noticed by previous studies is confirmed. Background flow states featuring a strong jet stream are also prone to barotropic instability.The eigenvalue analysis reveals the spatial structure of the associated Rossby modes and their growth rates, allowing to detect the presence of instabilities. We notice that, even in presence of a damping term, some background flow configurations allow wave instabilities to exist. According to the linear theory, the flow should diverge from the equilibrium state, since some waves are linearly unstable. Nonlinear simulations are performed to provide insights about the waves evolution in the unstable case. Such simulations reveal two interesting effects: 1) a damping effect operated by the nonlinear terms (i.e., the flow is unstable linearly but stable nonlinearly) for medium jet strengths; 2) a quasi-periodic behaviour around the unstable equilibrium state for the strongest jets, indicating the existence of a limit cycle. The linear analysis was still able to capture the unstable equilibrium state at the center of the limit cycle and to provide insights about the spatial structure of the dominant modes. These results indicate the usefulness of linearized approaches in the development of a reduced-order model to describe the barotropic instability mechanisms driving spherical Rossby waves.
Plastic routing through the Odaw catchment
Authors: Pinto Rose Boahemaa , Bogerd Linda , van Emmerik Tim , van der Ploeg Martine , Anhwere Duah Kwame , Uijlenhoet Remko
Published: February 2023

River catchments are important to consider when investigating the fate of plastics once introduced into the environment. However, plastic transport at the river catchment scale is rarely quantified. In this study, we present a catchment-scale field assessment of macroplastic litter in the Odaw (270 km2). The catchment was sub-divided into non-urban riverine, urban riverine and urban tidal zones based on the urbanisation level and riverine transport across the catchment. The riverine (river and riverbank) and terrestrial environments at ten locations along the catchment were monitored on three days in December, 2021. Floating litter items in the river were monitored by visual counting. At the riverbank and terrestrial environments, litter items were sampled in a designated area (5 x 2 m2) and categorised according to the River-OSPAR list (Schone-Rivieren, 2018). Results showed a high plastic flux (1125 items/h) in the urban riverine zone, which was higher by a factor of 16 and 2 to the plastic flux at the non-urban riverine and urban tidal zones, respectively. Terrestrial and riverbank plastic density was highest closest to the river mouth (urban tidal). The factor increase between the most upstream (non-urban riverine) and downstream (urban tidal) was larger for terrestrial than for riverbank. This shows the influence of urbanisation on the generation of mismanaged plastics in the catchment. Top three plastic polymer types observed in the catchment were PO soft, EPS and Multilayer. However, at each zone, the top three plastic polymer types varied with PO Soft as the most dominant at each zone. The highest abundance of PO soft, EPS and multilayer was found at the urban riverine (56%), urban tidal (31%) and non-urban riverine (24%) zones respectively. Our findings provide information on the spatial variation of plastic transport in the Odaw catchment and therefore can help create better strategies to manage the plastic pollution problem in this catchment. Future work will further explore the potential sources and temporal sink zones in the catchment.ReferenceSchone-Rivieren (2018). Handleiding voor monitoring, pp. 1–3.
Severe windstorm projections for Europe
Authors: Leach Nicholas James , Messori Gabriele , Crawford Alex , Wada Ryota , Woodhouse Sally , Burke Claire
Published: February 2023

Extreme windstorms are of considerable interest due to their potential to cause significant socio-economic damages over very large areas of land. As a result, understanding how climate change may affect the characteristics of the most severe storms is an important question for adaptation planing. However, projections of how the hazard associated with windstorms will change in the future are highly uncertain.Here, we use an efficient statistical approach that characterises individual windstorms in terms of their intensity and exposure to estimate the present-day risk from such storms. We then use a methodology used widely in detection and attribution of climate change to assess how such characteristics may change into the future. Using windstorms simulated by a diverse set of high-resolution regional climate model projections for Europe, the EURO-CORDEX ensemble, we provide projections of risk over a range of future climate scenarios. Finally, we explore how the variety of driving and regional models influence the associated uncertainties, and how considering the performance and independence of the models can improve the robustness of the projections.
The mechanical evolution of the European continental crust through the Alpine orogenic cycle: insights from the Rotondo granite (Gotthard massif, Central Swiss Alps)
Authors: Ceccato Alberto , Behr Whitney M. , Zappone Alba S.
Published: February 2023

The deformation sequence recorded in granitoid units of the External Crystalline Massifs (Aar-Gotthard, Mont Blanc) is commonly characterized by a brittle-ductile-brittle evolution. The same evolution is here described for the Rotondo granite (Gotthard Massif) and used to constrain the mechanics, rheology and timing of this brittle-ductile-brittle deformation sequence. Here we present meso- and microstructural, mechanical and petrochronological analyses of the deformation features of the Rotondo granite.We distinguish four different deformation stages in the Rotondo granite based on structures, cross-cutting relationships, PT conditions and in-situ dating. The earliest structural features are brittle cataclasites and hydraulic breccias that appear to have formed under variable differential stresses and elevated fluid pressures. They host garnets that grew over the sheared texture and record peak metamorphic conditions of 600 ºC and 0.9 GPa. Ductile mylonitic shear zones overprint and exploit these early brittle structures at retrograde conditions (550 ºC and 0.7 GPa, ~18 Ma in-situ Rb-Sr in white mica), at differential stress <40 MPa and elevated fluid pressures during Alpine exhumation exemplified by the development of syn-kinematic, subhorizontal quartz veins. Strike-slip tectonics was dominant afterwards, as exemplified by the occurrence of brittle-ductile shear zones developed sequentially through decreasing fluid pressure and increasing differential stress conditions. The pre-existent mylonitic shear zones were initially partially reactivated during strike-slip shearing (400 ºC and 0.5 GPa, ~14 Ma in-situ Rb-Sr in white mica) and subsequently overprinted by conjugate brittle faults. The latest deformation stage involves zeolite- gouge-bearing faults that exploit pre-existent structural discontinuities, aided by low friction coefficients of the fault gouges. All three youngest deformation stages are interpreted to be Alpine in age and are observed to exploit/reactivate the earliest (presumably Variscan or prograde) breccias and cataclasites.The structural sequence of the Rotondo granite exemplifies the effects of pre- and syn-orogenic structural inheritance and variable metamorphic fluid conditions on the mechanical evolution, rheology and strain distribution of crystalline (granitoid) basement units of the European continental crust through the Alpine orogenic cycle.
Forms and Regulation of the Paleozoic Marine Latitudinal Diversity Gradient
Authors: Wen Die , Fan Junxuan , MacLeod Norman , Shi Yukun
Published: February 2023

The pattern of taxonomic richness peaking at the equator and dwindling off towards the Earth’s poles is known as the latitudinal diversity gradient (LDG). It was among the first global biodiversity pattern to be discovered, but is also one that, to date, has resisted comprehensive explanation. The Paleozoic provides a unique perspective to study how the LDG has variated and its form regulated is in the deep time. Here a summary of genus-level global marine invertebrates fossil data was obtained from the Paleobiology Database and used to evaluate LDG patterns for each Paleozoic stage. After data cleaning, this dataset included 485,129 occurrences of 18,234 genera distributed across 85,259 fossil localities. Bias in the observed fossil record, as recorded by these data, was addressed via rarefaction, shareholder quorum subsampling and bootstrap approaches. Pattern analyses of LDG form across Paleozoic stages reveal seven main patterns. Location of latitudinal peak diversity relative to the paleoequator and the steepness of the LDG slopes across latitudes, represent the features that distinguish these seven LDG patterns across Paleozoic time. Although all observed LDG patterns are characterized by a low-latitude richness peak from 30°N to 30°S, they are not symmetrical about the paleoequator in most stages. Comparison of variation in LDG geometries with time-series variation in a suite of environmental proxies suggests that variation in tectonic plate configurations and aspects of global climate change are associated closely with the time-series of LDG variation. These associations suggest that the form of the LDG at different points in earth history was structured by secular changes in global climate states since tectonic configurations would be expected to affect organismal populations primarily through variation in environmental state. Moreover, our results suggest that the current LDG represents a form that is exceptionally balanced – and so somewhat atypical – when compared with LDG forms that existed over much of the Paleozoic.
The influence of geographical factors on COVID-19 outbreak: A literature review
Authors: Coratza Paola , Ghinoi Alessandro , Palandri Lucia , Righi Elena , Rizzi Cristiana , Soldati Mauro , Vandelli Vittoria
Published: February 2023

A significant number of papers focusing on the relationships between COVID-19 diffusion and geographic factors is available in literature. The same applies to the use of geographic techniques (e.g., spatial tools and mapping) for the study of the pandemic. Although the literature on these topics is already abundant, a detailed and comprehensive review is still lacking.In this context, the purpose of this paper is to fill the existing gap by presenting a literature review of geographical studies dealing with the COVID-19 pandemic. The review is aimed at: i) understanding the role of geographic/territorial determinants (e.g., geographic location of confirmed cases, climatic and environmental characteristics, urbanization) in the spread of COVID-19; ii) identifying common approaches, materials, and methods used in the study of the COVID-19 outbreak from a geographical perspective; iii) recognising possible research gaps to address future in-depth analyses.To achieve these goals a literature review was made concerning the application of geographical approaches for the study of one or more geographical factors/variables, as well as socioeconomic factors in relation to the outbreak and diffusion of the COVID-19 pandemic. The main academic literature databases were inquired. More than 80 papers were reviewed and categorized according to different criteria, e.g., considered variables, investigated period, spatial and temporal resolution and applied methodologies.This research is part of an interdisciplinary project (“DISCOV19”) funded by the University of Modena and Reggio Emilia and aiming at identifying the main vulnerability and risk factors related to COVID-19 outbreak and at formulating prevention and management schemes with a focus on the Province of Modena (Northern Italy). The investigation crosses different disciplines: i) public health epidemiology, investigating the contagion modalities and health and socio-demographic predisposing factors; ii) economic-statistical methodology, pointing out the structural characteristics of the networks that convey the contagion and the main social, technological and management vulnerabilities with respect to COVID-19 spread; iii) geography and geomorphology, for thematic mapping and spatial analysis of COVID-19 outbreak and understanding the role of environmental and physical-geographical factors on COVID-19 incidence. The review here presented fits into this context being one of the first outputs of the project implementation.
Functional traits of Zea mays L. varieties determine drought effects on soil structure and carbon allocation in the rhizosheath
Authors: Steiner Franziska , Wild Andreas J. , Tyborski Nicolas , Tung Shu-Yin , Köhler Tina , Buegger Franz , Carminati Andrea , Eder Barbara , Groth Jennifer , Hesse Benjamin D. , Pausch Johanna , Lüders Tillmann , Vahl Wouter , Wolfrum Sebastian , Mueller Carsten W. , Vidal Alix
Published: February 2023

The spatial arrangement of the soil surrounding the root can improve plant resource acquisition under drought and is closely related to the fate of soil organic carbon (SOC). Thus, the formation of soil structure and the establishment of a stable rhizosheath can potentially improve plant drought resistance and contribute to maintained crop yields during drought events. Yet, soil structure formation is a complex process determined by the interaction between various functional plant and soil properties, such as the soil (micro)biome, root exudation, or root morphological characteristics. To date, it is not understood how water scarcity affects soil aggregation in the vicinity of roots, by which functional traits these drought effects can be modified, and how this feedbacks on the cycling of SOC. Thus, we investigated drought effects on rhizosheath properties and their link with functional plant traits. We conducted a greenhouse experiment with 38 maize varieties where half of the plants were grown under optimum moisture, while the second half of replicates were subjected to drought stress after an initial establishment phase. For each plant, the rhizosheath soil was sampled and its aggregate size distribution, carbon (C) and nitrogen (N) content, and the proportion of newly maize-derived C were analysed via natural abundance 13C. In addition, we recorded functional plant and rhizosphere traits, such as morphological and chemical root properties, microbial enzyme activities, and plant biomass.Drought-stressed plants formed lower amounts of rhizosheath, with a decreased physical aggregate stability and increased concentrations of SOC, N, and newly maize-derived C. Furthermore, under drought larger proportions of the elements were allocated into the microaggregate fractions. In particular, maize-derived C, along with N, accumulated under drought stress in the smaller aggregate size classes of the rhizosheath. Maize varieties forming larger amounts of roots under drought stress tended to maintain higher macroaggregate stability in the rhizosheath. In contrast, cultivars that invested little in root growth but promoted higher microbial enzyme activities in the rhizosheath and maintained root N contents under drought were associated with a strong accumulation of maize-C and N in the smaller aggregate size classes. Trait-based experimental approaches, such as the one presented here, are deepening our mechanistic understanding of drought effects in the crop rhizosheath and can thus help to guide future crop selection for improved drought resistance.
Performance of global and regional ionospheric maps over a low latitude region
Authors: Jerez Gabriel , Hernández-Pajares Manuel , Goss Andreas , Prol Fabricio , Alves Daniele , Monico João , Schmidt Michael
Published: February 2023

Vertical total electron content (VTEC) values are commonly distributed in regular grids by means of the so-called global ionospheric maps (GIMs). Besides the global products, several analysis centers also compute regional ionospheric maps (RIMs) which often incorporate a larger number of GNSS stations, i.e. a denser network, allowing the description of finer structures of the ionosphere. The different global and regional ionospheric products can also present some differences, for instance related to spatial and temporal resolutions. In this work we present a comparison of the performance of seven ionospheric maps: four global, two regional and one hybrid product, which combines regional and global data. The assessment/validation is performed based in ionosonde data and global navigation satellite systems (GNSS) positioning. Data from ionosondes and GNSS stations over the Brazilian region is used during a week with active geomagnetic storm. In general, the performance of RIM products leads to better results considering the ionosonde data approach. The assessment with GNSS positioning leads to larger errors close to the equatorial anomaly; the best performance is obtained with the proposed hybrid product.
Effect of wind-driven rain on runoff, infiltration and soil erosion
Authors: Bahddou Sophia , Otten Wilfred , Whalley Richard , Shin Ho-Chul , El Gharous Mohamed , Rickson Jane
Published: February 2023

Soil erosion is a result of detachment and transport of particles or small aggregates from the soil surface. Previous research has predominantly focused on studying the effects of either rainfall or wind on soil erosion processes as separate erosive agents. To date, there have been only few studies into the simultaneous effect of both agents operating at the same time on soil erosion and hydrological processes. In this research, the effect of wind velocities on the erosivity of rainfall was studied, comparing windless rain (WLR) and wind-driven rain (WDR) events when applied to a sandy loam soil. A moderate slope gradient of 11%, a simulated rainfall intensity of 90 mm hr-1, a rainfall duration of 30 minutes and wind velocities up to 9 m s-1 were used. The runoff, infiltrate and soil loss (including splash erosion measured at different heights) were compared between the different events and treatments. The soil surface roughness was measured before and after the rainfall event, using a hand-held laser scanner, to evaluate the effect of WLR and WDR on the surface morphology. The outcome of this study shows that, for the smooth surface under WDR, infiltrate volumes were less than under WLR and decreased with increasing wind velocity, while the runoff volumes increased under WDR compared with WLR. The rate of rainsplash erosion increased under the WDR event compared to the WLR event at all heights. The amount of splash-eroded particles decreased with height above the soil surface. We conclude that wind has an effect on the erosivity of rainfall; therefore, it should be considered in erosion studies.Acknowledgments: This work was funded by OCP group, Morocco
Stream erosion in analogue models
Authors: Reitano Riccardo , Clementucci Romano , Conrad Ethan M. , Corbi Fabio , Lanari Riccardo , Faccenna Claudio , Bazzucchi Chiara
Published: February 2023

The presence of a strong interaction between tectonic deformation and surface processes is widely recognized. Still, the nature of this interaction is difficult to unravel and quantify. In the last decades, analogue landscape evolution models have been widely implemented and employed in different tectonic settings, to complement field campaign studies. Since the aim of these analogue models is to help the interpretation of data coming from natural prototypes, it is important to test how well empirical erosional laws built upon natural landscapes, explain analogue model behavior. We perform a series of experiments for a straight interpretation of the relationship between applied boundary conditions and analogue landscape evolution. The selected analogue material is composed of 40 wt.% of silica powder, 40 wt.% of glass microbeads, and 20 wt.% of PVC powder. The analogue material fills a rectangular box (30×35×5 cm3) placed over a reclined table. Over the box, a series of sprinklers generate a dense mist (i.e., rainfall) that triggers surface processes. The boundary conditions applied to the models are the imposed slope of the reclined table and the rainfall rate. We test three rainfall rates (9, 22, and 70 mm h-1) and three imposed slopes (10, 15, and 20°), analyzing how the combination of these boundary conditions results in different landscape metrics (e.g., basins length, basins width, drainage area, channel slope, erosional efficiency) and erosion rates. Results show that in models affected by high rainfall rates (70 mm h-1), the implemented analogue material is characterized almost no channelization, and erosion acts uniformly and diffusively over the models’ surface. Lower rainfall rates (9, 22 mm h-1) allow more discrete channelization instead. On the other hand, as expected, the imposed slope controls the amount of incision, so that the volumes of material removed by erosion increase moving from 10° to 20°. However, even if the maximum incision is generally controlled by the slope, the coupling with rainfall rate tunes the effectiveness of erosion. In this work we compare the imposed boundary conditions with the corresponding erosion rates, using geomorphic markers and landscape metrics to define if and how natural erosional laws apply to analogue landscape evolution models.