bluuebunny/crossref_metadata_2025 huggingface dataset:
The response of stratospheric ozone and dynamics to changes in atmospheric oxygen
Authors: Józefiak Iga , Sukhodolov Timofei , Egorova Tatiana , Rozanov Eugene , Chiodo Gabriel , Stenke Andrea , Peter Thomas
Published: March 2021

Photolysis of molecular oxygen (O2) maintains the stratospheric ozone layer, protecting living organisms on Earth by absorbing harmful ultraviolet radiation. The atmospheric oxygen level has not always been constant, and has been held responsible for species extinctions via a thinning of the ozone layer in the past. On paleo-climate timescales, it ranged between 10 and 35% depending on the level of photosynthetic activity of plants and oceans. Previous estimates, however, showed highly uncertain ozone (O3) responses to atmospheric O2 changes, including monotonic positive or negative correlations, or displaying a maximum in O3 column around a certain oxygen level. Motivated by these discrepancies we reviewed how the ozone layer responds to atmospheric oxygen changes by means of a state-of-the-art chemistry-climate model (CCM). We used the CCM SOCOL-AERv2 to assess the ozone layer sensitivity to past and potential future concentrations of atmospheric oxygen varying from 5 to 40 %. Our findings are at odds with previous studies: we find that the current mixing ratio of O2, 21 %, indeed maximizes the O3 layer thickness and, thus, represents an optimal state for life on Earth. In the model, any alteration in atmospheric oxygen would result globally in less total column ozone and, therefore, more UV reaching the troposphere. Total ozone column in low-latitude regions is less sensitive to the changes, because of the “self-healing” effect, i.e. more UV entering lower levels, where O2 photolyzes, can partly compensate the O3 lack higher up. Mid- and high-latitudes, however, are characterized by ±20 DU ozone hemispheric redistributions even for small (±5 %) variations in O2 content. Additional regional patterns result from the hemispheric asymmetry of meridional transport pathways via the Brewer-Dobson circulation (BDC). We will discuss the different ozone responses resulting from changes in the BDC. These effects are further modulated by the influence of ozone on stratospheric temperatures and thus on the BDC. Lower O2 cases result in a deceleration of the BDC. This renders the relation between ozone and molecular oxygen changes non-linear on both global and regional scales.
Detecting flood drivers through large-sample geomorphology
Authors: Slater Louise
Published: March 2021

Many fluvial processes have long been treated as stationary, fluctuating within an unchanging envelope of variability. However, a large body of evidence has revealed that shifts in climate, land cover and river basin management may manifest locally along river networks through hydrological and geomorphic change. Measuring the effect of these changes on the local flood risk requires a large sample approach. Large sample geomorphology has existed for many decades but is currently undergoing a step-change characterised by computational techniques, scalability, and growing interdisciplinarity. This step-change has been assisted by the availability of remotely sensed datasets describing the land surface (including satellite, airborne and ground-based acquisitions), alongside other datasets more conventionally employed in hydro-climatology (including weather and climate observations, reanalysis, and projections). Within this context, data science and AI approaches facilitate pattern detection and the testing of both long-standing and emerging theories, to derive insights about processes and mechanisms at play. Here, we will discuss the value of large-sample geomorphology for understanding nonstationary landscapes and the associated flood risk. We will provide insights into the promise and pitfalls of large-sample approaches within an evolving discipline, and discuss ways forward, with more systematic hypothesis testing and developing projections of future change.    
Impacts of nano-clay addition to soils: a meta-analysis
Authors: Maddox Grace , Bell Stephen , Barriocanal Carles
Published: March 2021

Nano-sized clay particles exhibit unique physicochemical properties within soil matrices relevant to several areas of applied environmental sciences. The amendment of soils with nano-clays in field, lab, and greenhouse settings has been increasingly studied over recent decades from various disciplinary perspectives. In general, nano-clay as a soil amendment is seen as a potentially effective and economically feasible method for managing soil resources. However, no comprehensive review and quantification of the impacts of nano-clay amendment on soil physical, chemical, and biological properties has been undertaken, which limits its uptake and application. Here, we provide a review of the impacts of nano-clay addition in soil, using a meta-analytical approach considering soil health parameters (e.g., organic carbon, water retention, cation exchange, pH, pollutant concentration). Preliminary results synthesizing field and lab experiments indicate a wide range of positive effect sizes across key soil properties, with only limited benefits occurring in specific cases. Our results highlight the significant potential of nano-clay as a soil amendment in diverse applications, especially when coupled with the economic and logistical suitability of nano-clay amendment globally.
CO2 fracturing using the phase field approach for the brittle fracture
Authors: Mollaali Mostafa , Ziaei-Rad Vahid , Shen Yongxing
Published: March 2021

To simulate CO2 fracturing under an isothermal condition, we propose a phase field model. We take advantage of the ability of the phase field approach to predict fracture initiation and branching, as well as to avoid tracking the fracture path. We model the CO2 as a compressible fluid by modifying Darcy's law. In particular, we assume that the permeability is correlated to the value of the phase field by the exponential function. The dependence of the CO2 density as a function of the pressure is captured by the Span-Wagner state equation. The computed pressure breakdown values show good agreement with analytical solutions and experimental results.
Near real-time identification of extreme events for weather index insurance using machine learning algorithms
Authors: Cesarini Luigi , Figueiredo Rui , Monteleone Beatrice , Martina Mario
Published: March 2021

A steady increase in the frequency and severity of extreme climate events has been observed in recent years, causing losses amounting to billions of dollars. Floods and droughts are responsible for almost half of those losses, severely affecting people’s livelihoods in the form of damaged property, goods and even loss of life. Weather index insurance is an innovative tool in risk transfer for disasters induced by natural hazards. In this type of insurance, payouts are triggered when an index calculated from one or multiple environmental variables exceeds a predefined threshold. Thus, contrary to traditional insurance, it does not require costly and time-consuming post-event loss assessments. Its ease of application makes it an ideal solution for developing countries, where fast payouts in light of a catastrophic event would guarantee the survival of an economic sector, for example, providing the monetary resources necessary for farmers to sustain a prolonged period of extreme temperatures. The main obstacle to a wider application of this type of insurance mechanism stems from the so-called basis risk, which arises when a loss event takes place but a payout is not issued, or vice-versa.

This study proposes and tests the application of machine learning algorithms for the identification of extreme flood and drought events in the context of weather index insurance, with the aim of reducing basis risk. Neural networks and support vector machines, widely adopted for classification problems, are employed exploring thousands of possible configurations based on the combination of different model parameters. The models were developed and tested in the Dominican Republic context, leveraging datasets from multiple sources with low latency, covering a time period between 2000 and 2019. Using rainfall (GSMaP, CMORPH, CHIRPS, CCS, PERSIANN and IMERG) and soil moisture (ERA5) data, the machine learning algorithms provided a strong improvement when compared to logistic regression models, used as a baseline for both hazards. Furthermore, increasing the number of information provided during model training proved to be beneficial to the performances, improving their classification accuracy and confirming the ability of these algorithms to exploit big data. Results highlight the potential of machine learning for application within index insurance products.
Improved estimation of global vegetation uptake of carbonyl sulfide (COS) in a biosphere model (SiB4) 
Authors: Cho Ara , Kooijmans Linda , Krol Maarten
Published: March 2021

The atmospheric trace gas ‘Carbonyl Sulfide (COS)’ has been identified as a possible tracer to estimate global Gross Primary Production (GPP). This is because COS is taken up similarly to CO2 uptake through plant stomata and has almost no respiration. In addition to vegetation activity, COS is removed by soil and chemical reaction in the atmosphere. It enters the atmosphere by emission from oceans and anthropogenic sources (e.g., rayon production). Plants play an important role in the seasonal COS drawdown, but the models that simulate COS biosphere exchange have considerable uncertainty due to lack of observation. The uncertainty is mainly related to the poorly defined ambient COS mixing ratio and enzyme activity, processes that control COS uptake. The ambient COS molecules diffuse into stomatal pores and mesophyll cells, where the molecules are hydrolyzed by the enzyme Carbonic Anhydrase (CA). Due to the lack of understanding of CA activity, previous studies scaled the COS mesophyll uptake with the maximum Rubisco deposition velocity (Vmax), relevant for photosynthesis, and only used the associated temperature response.

This study will improve the estimation of COS vegetation uptake in the Simple Biosphere model version 4 (SiB4), corresponding to different COS mixing ratios from an atmospheric inversion and various environmental conditions. COS flux observations from Europe and North America will be applied. We aim to identify and present: (i) the response of the COS uptake to varying COS mixing ratios and environmental conditions (temperature, humidity, and light), (ii) application of the relationships derived by (i) to the estimation of global COS uptake by the SiB4 model, (iii) investigate the implications for SiB4 calculation of CO2 photosynthesis by the SiB4 model. Unlike the original SiB4 model, where CA uptake is proportional to Vmax and the temperature response identical for all plant types and environments, we will show the nonlinear CA responses to COS mixing ratio, temperature, humidity and light.

 
Mapping forest tree species in high resolution UAV-based RGB-imagery by means of convolutional neural networks
Authors: Schiefer Felix , Kattenborn Teja , Frick Annett , Frey Julian , Schall Peter , Koch Barbara , Schmidtlein Sebastian
Published: March 2021

With consumer-grade unmanned aerial vehicles (UAVs) on the rise, which enable easy, time-flexible, and cost-effective acquisition of very high-resolution RGB data, the mapping of forest tree species using solely RGB imagery is of high interest, as it does not rely on sophisticated sensors, does not require extensive calibration and preprocessing and, therefore, enables the application by a wide audience. In combination with convolutional neural networks (CNNs), which particularly exploit spatial patterns and, therefore, highly benfit from very high-resolution remote sensing, this offers great potential for accurately mapping forest tree species.

Here, we present the findings of our recent study, in which we used very high-resolution RGB imagery from UAVs in combination with CNNs for the mapping of forest tree species. In this study, we used multicopter UAVs to obtain very high-resolution (<2 cm) RGB imagery over 51 ha of temperate forests in the Southern Black Forest region, and the Hainich National Park in Germany. To fully harness the end-to-end learning capabilities of CNNs, we used a semantic segmentation approach (U-net) that concurrently segments and classifies tree species from imagery. With a diverse dataset in terms of study areas, site conditions, illumination properties, and phenology, we accurately mapped nine tree species, three genus-level classes, deadwood, and forest floor (mean F1-score 0.73). We found that a coarser spatial resolution substantially reduced the model accuracy (mean F1-score of 0.26 at 32 cm resolution) and that larger tile sizes during CNN training negatively affected the model accuracies for underrepresented classes. Additional height information from normalized digital surface models slightly increased the model accuracy but simultaneously increased computational complexity and data requirements. Our results highlight the key role that UAVs can play in the mapping of forest tree species, given that air- and spaceborne remote sensing currently does not provide comparable spatial resolutions. Given the end-to-end learning capabilites of CNNs extensive preprocessing becomes partly obsolete, whereas the use of a large and diverse dataset facilitates a high degree of generalization of the CNN, thus fostering transferability. The synergy of high-resolution UAV imagery and CNN provide a fast and flexible yet accurate means of mapping forest tree species.

In this contribution, we will give an outlook on how the combination of UAV imagery and CNNs can be integrated with multitemporal satellite imagery (Sentinel-1 and Sentinel-2) in order to extrapolate the UAV-based tree species maps to larger areas.
Mapping Surface Winds on Mars from the Global Distribution of Barchan Dunes Employing an Instance Segmentation Neural Network
Authors: Rubanenko Lior , Lapotre Mathieu G.A. , Schull Joseph , Perez-Lopez Sebastian , Fenton Lori K. , Ewing Ryan C.
Published: March 2021

The surface of Mars is riddled with dunes that form by accumulating sand particles that are carried by the wind. Since dune geometry and orientation adjust in response to prevailing wind conditions, the morphometrics of dunes can reveal information about the winds that formed them.

Previous studies inferred the prevailing local wind direction from the orientation of dunes by manually analyzing spacecraft imagery. However, building a global map remained challenging, as manual detection of individual dunes over the entire Martian surface is impractical. Here, we employ Mask R-CNN, a state-of-the-art instance segmentation neural network, to detect and analyze isolated barchan dunes on a global scale.

We prepared a training dataset by extracting Mars Context Camera (CTX) scenes of dune fields from a global CTX mosaic, as identified in the global dune-fields catalog. Images were cropped and standardized to a resolution of 832x832 pixels, and labeled using Labelbox’s online instance segmentation platform. Image augmentation and weight decay were employed to prevent overfitting during training. By inspecting 100 sample images from the validation database, we find that the network correctly identified ~86% of the isolated dunes, falsely identifying one feature as a barchan dune in a single image.

After dune outlines are detected, they are automatically analyzed to extract the dominant-wind and net sand-flux directions using traditional computer vision techniques. We expect our future surface-wind dataset to serve as a constraint for atmospheric global circulation models to help predict weather events for upcoming in situ mission as well as shed new light on the recent climate history of Mars.
Thermochronology as a key to deciphering controls on landscape evolution in northern Victoria Land (Transantarctic Mountains) 
Authors: Roehnert Daniela , Lisker Frank , Balestrieri Maria Laura , Grewe Luca , Balbi Evandro , Läufer Andreas , Crispini Laura , Spiegel Cornelia
Published: March 2021

Northern Victoria Land constitutes the Pacific terminus of the Transantarctic Mountains (TAM) on the western shoulder of the Cenozoic West Antarctic Rift System. It is characterised by a distinct morphological transition from an elevated peneplain that dominates throughout most of the TAM to a strongly undulating relief with prominent narrow crests and alpine peaks. This contrast is associated with a lithological change from high-grade metamorphics and granitoids to low-grade metasedimentary rocks that contain only few scattered igneous bodies.

New high-resolution thermochronological data (fission-track and (U-Th-Sm)/He) from more than 60 locations in the Southern Cross Mountains and Mountaineer Range of northern Victoria Land provide the basis for studying regional exhumation and uplift with particular focus on the establishment of landscape contrasts. In an integrated approach, differences in topography are examined with respect to regional and local controls including tectonics, lithology and climate to identify differential trends and quantify the morphological evolution of the TAM and West Antarctic Rift System.

 

Two coastal profiles covering 2 to 3 km in elevation reveal apatite fission track ages from 23 to 45 Ma with mean track lengths of 13.3 – 14.7 μm. Corresponding (U-Th-Sm)/He apatite and zircon data range between 19 – 32 Ma and 24 – 27 Ma, respectively. The dates show distinctive spatial trends of increasing ages from north to south and at greater distance to the coast whereby younger cooling ages correlate with stronger terrain segmentation and higher topographic relief.

Thermal history modelling of the combined data indicates that accelerated cooling commencing at 35 Ma proceeded at progressively higher rates reaching >25°C/Ma in late stages. This cooling episode continued until at least 20 Ma and refers to exhumation from burial depths of more than 5 km, clearly exceeding the calculated overburden on adjacent crustal blocks to the south. Although rapid upper lithospheric cooling is a generic feature of northern Victoria Land, the current data demonstrates that Cenozoic exhumation dynamics were highly differential. Understanding these patterns requires thorough balancing of structural against isostatic factors, lithological against climate parameters and focussed local incision against large-scale denudation and levelling processes.
Source attribution of Particulate Matter for Berlin 2016-18, a study using the LOTOS-EUROS CTM
Authors: Pültz Joscha , Thürkow Markus , Banzhaf Sabine , Kranenburg Richard , Schaap Martijn
Published: March 2021

Air Quality in Berlin is a particular problem during winter episodes. During this episodes, local emissions are only one factor contributing to the high concentrations. The other factors are the lowered height of the planetary boundary layer and the advection of pollutants, some of which are produced in Eastern Europe. To trace the share of total pollution in Berlin for 2016-18 back to its origins, the Chemistry Transport Model (CTM) LOTOS-EUROS v2.1 (LOng Term Ozone Simulation EURopean Operational Smog, invented by TNO, Netherlands) is used, which also provides a labelling approach. Some specifications were made for the emission datasets used to drive the model, including emission dependencies on temperature (e.g. cold engine starts and heating degree-days for households).

The model results are evaluated using the German AirBase monitoring sites. An incremental approach (Lenschow et al., 2001) is used for the evaluation and estimation of the urban share of Berlin. The focus is on Particulate Matter (PM): PM10, PM2.5, and the coarse-mode fraction (PM10-PM2.5). Due to the seasonal variability of PM and its composition, seasonal differentiation is investigated. The labelling approach provided in LOTOS-EUROS allows to distinguish between the sources relevant for Berlin’s PM pollution, with the focus of this work on local contributions such as households and traffic on the one hand and regional contributions from Berlin itself and Germany’s Eastern European neighbors (Poland and the Czech Republic) on the other hand.

This study is in relation to the “Berliner Luftreinhalteplan” (Berlin Clean Air Plan).
The need for clearer climate target definitions - illustrating ambiguities of net zero CO2-eq targets
Authors: Mengis Nadine , Oschlies Andreas
Published: March 2021

Article 4 of the Paris Agreement calls for a “balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century”. It is not made explicit if this balance should be achieved for each of the greenhouse gases (GHGs) individually or if some sum of all GHGs is supposed to become net-zero. This confusion translated into several declared climate targets, that range from carbon-neutral, over GHG-neutral to climate-neutral, and sometimes use these terms interchangingly. However, these targets imply different trajectories in terms of single GHG emissions and result in vastly different temperature trajectories.
Here, we show the implications of this confusion concerning declared climate target metrics, using the most commonly used metric of CO2-equivalent emissions. The same trajectory of net-zero-2050 CO2-equivalent emissions, shows vast differences in short term and long-term temperature and carbon cycle responses, depending on the distribution of CO2-equivalent emissions across the different GHGs.
We emphasize that achieving net zero CO2 emissions remains a necessary precondition for long-term temperature stabilization. We also show that methane emissions reduction can have large short term benefits, as it would strongly reduce the short term temperature and thereby increase the natural carbon uptake. Going forward we recommend to aim for more transparency in declared climate goals and suggest aiming to achieve net zero anthropogenic emissions for all GHGs individually.
Seasonal stress inversion trends of RTS in Song Tranh2 reservoir, Vietnam
Authors: Nowaczyńska Izabela , Lizurek Grzegorz , Wiszniowski Jan , Plesiewicz Beata
Published: March 2021

The Song Tranh 2 hydropower construction is located in the Quang Nam province (central Vietnam), it has a reservoir volume of 740 million cubic meters of water and a dam height of 96 m. The reservoir was filled to capacity for the first time in February 2011. The seismicity in the vicinity of reservoir is example of reservoir triggered seismicity(RTS). The natural seismic activity of the Song Tranh 2 reservoir is very low. After the reservoir was filled, the seismic activity increased, and the number and frequency of the tremors also changed as the water level changed. Water level changes are accelerating the tectonic process leading the critically stressed faults to slip. Data suggest that reservoir exploitation stress field changes as triggering origin of this seismicity. The stress inversion method was used to check if there were any seasonal trends. The inverted stress tensor and, in particular, the stress ratio, which is very sensitive to data quality and scope and difficult to accurately retrieve, can be influenced by porous pressure changes. Has been checked, how the average annual seismic activity is related to the change of the water level and if it implies the orientation of the principal stress during high and low water levels in the reservoir. The pore pressure changes and the stress ratio changes were also estimated in relation to the high and low water level periods.
A preliminary assessment of the accuracy of the VGOS geodetic products: implications for the terrestrial reference frame and Earth orientation parameters
Authors: Mondal Dhiman , Elosegui Pedro , Barrett John , Corey Brian , Niell Arthur , Ruszczyk Chester , Titus Michael
Published: March 2021

The next-generation VLBI system called VGOS (VLBI Global Observing System) has been designed and built as a significant improvement over the legacy geodetic VLBI system to meet the accuracy and stability goals set by the Global Geodetic Observing System (GGOS). Improved geodetic products are expected as the VGOS technique transitions from demonstration to operational status, which is underway. Since 2019, a network of nine VGOS stations has been observing bi-weekly under the auspices of the International VLBI Service for Geodesy and Astrometry (IVS) to generate standard geodetic products. These products, together with the mixed-mode VLBI observations that tie the VGOS and legacy networks together will be contributions to the next realization of the International Terrestrial Reference Frame (ITRF2020). Moreover, since 2020 a subset of 2 to 4 VGOS stations has also been observing in a VLBI Intensive-like mode to assess the feasibility of Earth rotation (UT1) estimation using VGOS. Intensives are daily legacy VLBI observations that are run on a daily basis using a single baseline between Kokee Park Geophysical Observatory, Hawaii, and Wettzell Observatory, Germany, made with the goal of near-real-time monitoring of UT1. In this presentation, we will describe the VGOS observations, correlation, post-processing, and preliminary geodetic results, including UT1. We will also compare the VGOS estimates to estimates from legacy VLBI, including estimates from mixed-mode observations, to explore the precision and accuracy of the VGOS products.
L-band vegetation optical depth as an indicator of plant water potential in a temperate deciduous forest stand
Authors: Holtzman Nataniel , Anderegg Leander , Kraatz Simon , Mavrovic Alex , Sonnentag Oliver , Pappas Christoforos , Cosh Michael , Langlois Alexandre , Lakhankar Tarendra , Tesser Derek , Steiner Nicholas , Colliander Andreas , Roy Alexandre , Konings Alexandra
Published: March 2021

Vegetation optical depth (VOD) retrieved from microwave radiometry correlates with the total amount of water in vegetation. In addition to depending on overall biomass, the total amount of water in vegetation varies with relative water content, which is monotonically related to plant water potential, a quantity that drives plant hydraulic behavior. Thus there is a possible relationship between VOD and plant water potential. Previous studies have found evidence for that relationship on the scale of satellite pixels tens of kilometers across, but these comparisons suffer from significant scaling error. Here we used small-scale remote sensing to test the link between remotely sensed VOD and plant water potential. We placed an L-band radiometer on a tower above the canopy looking down at red oak forest stand during the 2019 growing season in the northeastern United States. We retrieved VOD with a single-channel algorithm based on continuous radiometer measurements and in-situ soil moisture data. We also measured water potentials of stem xylem and leaves on trees within the stand.

VOD exhibited a diurnal cycle similar to that of leaf and stem water potential, with a peak at approximately 5 AM. Over the whole growing season, VOD was also positively correlated with both the water potential of stem xylem and the xylem's dielectric constant (a proxy for water content). The presence of moisture on the leaves did not affect the observed relationship between VOD and xylem dielectric constant. We used our observed VOD-water potential relationship to estimate stand-level values for a radiative transfer parameter and a plant hydraulic parameter, which compared well with the published literature. Our findings support the use of VOD for plant hydraulic studies in temperate forests.
Modeling the magnetic structure of CMEs in the inner heliosphere based on data-driven time-dependent simulations of active region evolution
Authors: Pomoell Jens , Kilpua Emilia , Price Daniel , Asvestari Eleanna , Sarkar Ranadeep , Good Simon , Kumari Anshu , Pal Sanchita , Daei Farhad
Published: March 2021

Characterizing the detailed structure of the magnetic field in the active corona is of crucial importance for determining the chain of events from the formation to the destabilisation and subsequent eruption and propagation of coronal structures in the heliosphere. A comprehensive methodology to address these dynamic processes is needed in order to advance our capabilities to predict the properties of coronal mass ejections (CMEs) in interplanetary space and thereby for increasing the accuracy of space weather predictions. A promising toolset to provide the key missing information on the magnetic structure of CMEs are time-dependent data-driven simulations of active region magnetic fields. This methodology permits self-consistent modeling of the evolution of the coronal magnetic field from the emergence of flux to the birth of the eruption and beyond. 

In this presentation, we discuss our modeling efforts in which time-dependent data-driven coronal modeling together with heliospheric physics-based modeling are employed to study and characterize CMEs, in particular their magnetic structure, at various stages in their evolution from the Sun to Earth. 
Partitioning of trace metals in cave (and cave-analogue) carbonate precipitates – towards a quantitative hydrological proxy in stalagmites 
Authors: Höpker Sebastian N. , Goswami Bedartha , Grainger Megan , Breitenbach Sebastian F. M. , Hansen Maximilian , Hartland Adam
Published: March 2021

Speleothems (secondary cave carbonate deposits) are particularly valuable for studying past climates over a range of temporal and spatial scales, owing to their continuous growth and exceptional viability for radiometric dating. However, the interpretation of many speleothem-based palaeoenvironmental proxies (e.g., stable isotope ratios δ18O and δ13C) in terms of particular environmental or climatic controls remains challenging, and is typically limited to qualitative reconstructions of past environmental conditions and dynamics.

In this study, we develop a novel class of quantitative hydrological proxies by exploring the kinetic behaviour of a suite of first-row transition metals (e.g., Ni, Cu, Co) found in stalagmites. The transport of these elements from the surface to the cave is strongly controlled by the binding to natural organic matter (NOM) present in infiltrating waters. The rate of dissociation of such metal-NOM complexes at the dripwater-stalagmite interface has recently been suggested to determine the availability of these elements for the incorporation into precipitates (Hartland & Zitoun, 2018). The link between NOM-complex dissociation and metal availability for deposition presents an opportunity to quantitatively relate respective carbonate metal concentrations to the time available for complexes to disintegrate and release metals within the thin water films on stalagmite surfaces.

We present preliminary analyses assessing trace metal kinetics and partitioning in monitored natural cave settings, as well as cave-analogue experimental setups. Our findings demonstrate the contrasting controls on the concentrations of different elements in speleothems, and highlight the potential for kinetically-limited elements in stalagmites to enable quantitative estimations of past hydrological variability.

 

References:

Hartland, A., Zitoun, R. (2018) Transition metal availability to speleothems controlled by organic binding ligands. Geochem. Persp. Let. 8, 22–25.
Remote Sensing Measurements of Carbon Dioxide and Methane over Northern Finland
Authors: Kivi Rigel , Hatakka Juha , Heikkinen Pauli , Laurila Tuomas , Lindqvist Hannakaisa , Chen Huilin
Published: March 2021

Remote sensing measurements of carbon dioxide and methane at the Sodankylä facility in northern Finland cover a 12-year time period. The measurements have been taken by a Fourier Transform Spectrometer (FTS), operating in the near-infrared spectral region.  The Sodankylä site is participating in the Total Carbon Column Observing Network (TCCON). Here we present long-term measurements of column-averaged, dry-air mole fractions of carbon dioxide and methane and comparisons with satellite borne measurements. The relevant satellite missions include the TROPOspheric Monitoring Instrument (TROPOMI) on board of the Copernicus Sentinel-5 Precursor satellite, the Orbiting Carbon Observatory-2 (OCO-2) and the Greenhouse Gases Observing Satellite (GOSAT). We have performed AirCore observations in the vicinity of the TCCON instrument at Sodankylä during all seasons. AirCore measurements are directly related to the World Meteorological Organization in situ trace gas measurement scales. The AirCore data are used in this study to provide comparisons with remote sensing retrievals.
Tomorrow’s Cities: Multi-hazard interactions to inform disaster risk reduction in Istanbul
Authors: Hussain Ekbal , Cakti Eser , Yolcu Aslihan , Malamud Bruce , Gill Joel , Trogrlic Robert
Published: March 2021

Istanbul is a major global urban centre. With city expansion expected to continue over the next few decades there is a real opportunity for urban growth that incorporates disaster risk reduction (DRR). But in order to develop DRR inclusive urban development strategies we need to understand the breadth of hazards that can affect the city and their potential interactions.

To create a single hazard overview for the city we searched through peer-reviewed literature, reports, government websites and international disaster databases for hazard occurrences. Of the 34 natural hazards in our global hazard table encompassing five major hazard groups (geophysical, shallow process, meteorological, hydrological, climatological and extraterrestrial), we found 27 of these had occurred or had the potential to occur in Istanbul. Notable absences were snow avalanches, glacial outburst floods and direct volcanic hazards. However, ash dispersal models show that ash from volcanic eruptions in the Mediterranean can affect the city.

Additionally, we present an interaction matrix for hazards relevant to the city that shows how one hazard may trigger or increase the probability of another. We adapted the global hazard interaction matrix of Gill and Malamud (2014) by removing hazards that were not relevant to Istanbul and supplementing it with specific examples that have occurred in the city. We found 85 such interactions that reveal the potential for interacting chains of natural hazards.

We discuss how multi-hazard scenarios, developed through expert stakeholder engagement and based on the hazard interaction matrix, are an effective way to explore and communicate the dynamic variability of exposure, vulnerability and therefore, multi-hazard risk.
Impacts of Desalinated Irrigation Water in the Abu Dhabi surficial aquifer
Authors: Cherubini Claudia , Sadhasivam Sathish , Pastore Nicola , Ghirotti Monica
Published: March 2021

Abu Dhabi is one of the arid regions in the world having less than 100 mm of rainfall per annum. The renewability of freshwater occurs only in the eastern part. The groundwater resources under desirable quality are very concise due to limited dilution/rainfall and higher rate of evaporation. Hence, in recent decades, desalinated water has been introduced for agriculture activities and surplus desalinated water is injected into the aquifer as artificial recharge. This study is conducted to understand the impacts in the aquifer system caused by the introduction of desalinated water for agriculture activities and for aquifer recharge structures. The simulation was carried out from 2000 to 2050 using reported rate of groundwater pumping and of desalinated water with 0.1 g/l, 0.5 g/l, 1 g/l, 1.5 g/l and 2 g/l degrees of salinity. A wide range of decline in the groundwater table is noticed in the western part of the aquifer due to less rainfall recharge. The results confirm that this region demands either reduction in agricultural activities or additional usage of desalinated water by which the pumping of groundwater can be reduced further. The improvement in the groundwater quality is noticed in the aquifer due to the addition of less saline desalinated water into the aquifer. This study confirms the long term suitability of existing aquifer recharge structure. Also, it expresses the need of further management practices in quantifying the desalinated water contribution for agriculture activities.

 
Mobility modelling for simulation of spatial spread of infectious diseases
Authors: Knop Krzysztof , Smolak Kamil , Kasieczka Barbara , Rohm Witold , Smolarczyk Tomasz , Zyga Marcin
Published: March 2021

The COVID-19 pandemic has highlighted the importance of public health policies and crisis management. The spread of diseases is a complex phenomenon with many time-dependent variables, which hampers an accurate prediction of epidemic evolution. Models of epidemic spread play an important role in guiding in designing public health policies, enabling hypothetical scenarios simulation and rapid analyses of ongoing epidemics.

Over the last century disease spread models evolved from deterministic compartmental models into complex metapopulation and agent-based simulations. Today’s solutions consider many factors, not limiting to the disease itself but also simulating socio-demographic structure and population flows. In the era of globalisation, human mobility became the major factor of rapid disease spread. Although current models consider international and regional travels, used mobility models are simplistic. This limits the accuracy and spatio-temporal resolution of these simulations, providing daily cases updates aggregated to large regions.

We propose an agent-based mobility model, offering a simulation of hourly temporal resolution depicting mobility with less than a few hundreds of meters spatial precision. Agent-based models allow each simulation agent to assign different characteristics, e.g. susceptibility to infection, mobility behaviour.

We integrate our mobility model with disease spread simulation, using an agent’s interaction to detect virus transmission. In every time step of the model, the interaction between the agents, their current state and localisation of interaction are used to determine the probability of infection. Social interactions in the context of the spread of the disease are a fundamental element influencing the temporal and spatial extent of the disease. An essential aspect of our model is the integration of the simulation environment with the points-of-interests (POIs), which represent the destination of the majority of non-home-work related activities. We validate the accuracy of mobility replication and present hypothetical scenarios of disease spread in one of the large European cities, presenting capabilities of our solution.
The role of cows on OVOC exchanges of a pasture
Authors: Heinesch Bernard , Michel Colin , Amelynck Crist , Schoon Niels , Mozaffar Ahsan , Aubinet Marc , Bachy Aurélie , Dumortier Pierre
Published: March 2021

The presence of cows on a pasture considerably modifies exchanges of biogenic volatile organic compounds (BVOCs). By regulating the biomass present, they can have an impact on the constitutive flux (exchanges from soil and grass that are not induced by leaf wounding or trampling by cows) but they can also cause direct emissions from exhalation and indirect emissions by leaf injury (grazing), trampling and wastes. In this study conducted on the ICOS pasture site of Dorinne (Belgium), we disentangled these different sources/sinks for three oxygenated BVOCs commonly exchanged on grasslands (methanol, acetaldehyde and acetone), using a combination of turbulent flux measurements, enclosure flux measurements, tools to detect the presence and activity of cows in the footprint of the turbulent flux measurements and a flux footprint model. Direct exhalation emissions were low, representing only 2.3% and 10% of the spring total flux of methanol and acetone respectively. Comparison of grazed and non-grazed enclosures pointed out that emissions following leaf wounding were significant for all studied BVOCs, decreased exponentially with time to become negligible after maximum five days. Cow indirect emissions at the pasture scale (turbulent flux measurements) where likely dominated by grazing and were shown to be a major component of the total diurnal flux for each of the three studied BVOCs. Comparison with a hay meadow also showed that the temporal dynamics of those BVOC emissions were very different according to the grass management type, calling for specific parametrization in up-scaling emission models.
Validation of closed-form expressions for the atmospheric altimetry correction in ground-based GNSS reflectometry based on rigorous ray-tracing
Authors: Nikolaidou Thalia , Santos Marcelo , Williams Simon D. P. , Geremia-Nievinski Felipe
Published: March 2021

GNSS reflectometry (GNSS-R) ability to remote sense the Earth’s surface is affected by an atmospheric bias, as pointed out by several recent studies. In particular, sea level altimetry retrievals are biased in proportion to the reflector height, while by-products, such as tidal amplitudes, are underestimated. Previously, we developed an atmospheric ray-tracing procedure to solve rigorously the three-point boundary value problem of ground-based GNSS-R observations. We defined the reflection-minus-direct or interferometric delay in terms of vacuum distance and radio length. We clarified the roles of linear and angular refraction in splitting the total delay in two components, along-path and geometric. We introduced for the first time two subcomponents of the atmospheric geometric delay, the geometry shift and geometric excess. Finally, we defined atmospheric altimetry corrections necessary for unbiased altimetry retrievals based on half of the rate of change of the atmospheric delays with respect to sine of elevation angle. Later, for users without access to ray-tracing software, we developed closed-form expressions for the atmospheric delay and altimetry correction. The first expression accounts for the angular component of refraction (bending), leading to a displaced specular reflection point. The second one accounts for the linear component (speed retardation) in a homogeneous atmosphere. The expressions are parametrized in terms of refractivity and elevation bending, which can be obtained from empirical models, such as the GPT2 or Bennet’s, or fine-tuned based on in situ pressure and temperature. We also provide a correction for the satellite elevation angle such that the refraction effect is nullified. We validated these expressions against rigorous ray-tracing results and showed that the discrepancy is caused by assumptions in the derivation of the closed formulas. We found the corrections to be beneficial even for small reflector heights, as approximated half of the atmospheric effect originates above the receiving antenna at low satellite elevation angles.
Two different basalt provinces (MORB vs. WPB) in the evaporitic Permian Haselgebirge Formation (Eastern Alps, Austria) and possible tectonic implications
Authors: Leitner Christoph
Published: March 2021

The evaporitic Haselgebirge Formation hosts in many places small occurrences of basaltic rocks. The geochemistry of these basalts can potentially provide information about the tectonic setting of the Haselgebirge Formation and the evolution of the Meliata ocean, respectively. We present here 70 new XRF analyses of these basaltic rocks from various localities (Pfennigwiese, Annaberg, Wienern, Hallstatt, Moosegg, Lammertal) and compare the results with previous data from local studies (GRUBER et al., 1991; KIRCHNER 1979; KIRCHNER 1980a; KIRCHNER 1980b; KRALIK et al, 1984; LEITNER et al., 2017; SCHORN et al., 2013; ZIEGLER, 2014; ZIRKL, 1957). Based on the concentrations of immobile trace elements (Zr, Nb, Y, Ti), a predominance of MORB-like compositions is observed for the Lower Austrian occurrences and for the locality Wienern (Grundlsee). On contrast, basalts from the localities Lammertal, Moosegg and Hallstatt have predominantly within-plate-type compositions.

We discuss this striking regional (east-west) difference of basalt types in terms of existing palinspastic models for the Haselgebirge formation (LEITNER et al., 2017; STAMPFLI & BOREL, 2002; McCANN et al., 2006).

 

GRUBER, P., FAUPL, P., KOLLER, F. (1991) Mitt. Österr. Miner. Ges., 84, 77-100.

KIRCHNER, E. (1979) Tschermaks Min. Petr. Mitt. 26, 149-162.

KIRCHNER, E. (1980a) Mitt. Österr. Miner. Ges.71/72, 385-396.

KIRCHNER, E. (1980b) Verh. Geol. Bundesanstalt 1980, 249-279.

KRALIK, M., KOLLER, F., POBER, E. (1984) Mitt. Österr. Miner. Ges., 77, 37-55.

LEITNER, C., WIESMAIER, S., KÖSTER, M.H., GILG, H.A, FINGER, F, NEUBAUER, F. (2017) GSA Bulletin 129, 1537-1553.

McCANN, T., PASCAL, C., TIMMERMAN, M.J., KRZYWIEC, P., LÓPEZ-GÓMEZ, J., WETZEL, L., KRAWCZYK, C.M., RIEKE, H., LAMARCH, J. (2006) Mem. Geol. Soc. London, 32, 355-388.

SCHORN A, NEUBAUER F, GENSER J, BERNROIDER M (2013) Tectonophysics 583, 28-48.

STAMPFLI G.M., BOREL G.D. (2002) Earth Planet. Sci. Lett. 196, 17-33.

ZIEGLER, T. (2014) Unpubl. MSc thesis University of Salzburg, p. 174.

ZIRKL, E.J. (1957) Jb. Geol. Bundesanstalt 100, 10-137-177.
A global database of flood-protection levees on river deltas (openDELvE)
Authors: O'Dell Joey , Nienhuis Jaap H. , Cox Jana R. , Edmonds Douglas A. , Scussolini Paolo
Published: March 2021

Global flood modelling requires standardised global flood-protection levee datasets. Current datasets, however, are generally confined to territorial boundaries (national datasets) and are scarcely made public. Here we report on our effort to collect and standardise flood-protection levee data for river deltas from various sources to create a single, open source and FAIR-aligned global dynamic evolving river levee data environment (openDELvE).

openDELvE aggregates data from national databases (including the USACE National Levee Database, and the UK EA Asset Information Management System, amongst others) as well as data collected from reports, maps, and satellite imagery. We report primarily the land areas  that the levees have been designed to protect, and where additional data is available, the location of levees and unified attributes.  openDELvE currently contains 1601 mapped leveed area polygons distributed over 152 deltas, covering 28% of globally defined delta area. Out of the 152 deltas, which cover a total delta area of 239,043 km2, the levees registered in the database protect a land area of 42,342 km2. Additionally, more extensive data has been collected from a selection of freely accessible public national databases (mostly the UK and USA, and some of Australia) spanning 5,089 km of levees with additional unified attributes (e.g. levee height, crest width, construction material), and a semi-automated process is being used to extend and develop this layer.

The data is published aligned to FAIR-standards and is open-source, with an interactive viewing platform to supplement the data which is targeted for use in global river delta modelling and research. The viewing platform for the database incorporates a community-driven revision tool to encourage ongoing improvement and refinement of delta levee data, which can be extended to future projects as required. 