bluuebunny/crossref_metadata_2025 huggingface dataset:
Primary forests as indicators of global change and land use effects on carbon storage and greening trends
Authors: Ahlström Anders , Abel Christin , Asch Johanna , Canadell Josep , Ervander Ulrika , Fälthammar-de Jong Geerte , Georgiou Katerina , Hugelius Gustaf , Jackson Robert , Ljung Karl , Metcalfe Daniel , Pasqual Didac , Tian Feng , Wolf Julika
Published: March 2022

Forestry is a regionally dominant land use but the carbon and climate impact of boreal forest management is not well characterized, partly because no large-scale maps of managed and primary unmanaged forests exist. Northern land has greened considerably during the last decades and there is evidence of the growing dominance of the boreal biome in the global land sink of carbon. However it remains unclear what drives the observed changes, if it is management or environmental changes.

In this project we have mapped and classified the naturalness of more than 400 primary forests in Sweden. The primary forests are found from the temperate south to the boreal north of the country, and managed secondary forests are identified close to each primary forest forming spatial pairs of primary and secondary forests that share climate and landscape history but not management. The primary forests represent a natural baseline of ecosystem states and changes. Changes in these forests are driven by regional to global environmental change such as elevated CO2 concentrations, warming or nitrogen deposition. The managed forests on the other hand are influenced by both environmental changes and management. By studying the states and changes in the primary forests we can gain new knowledge in how ecosystems would have changed and what their states would have been with no management. By contrasting changes and states in the managed ecosystems we can estimate the long-term influence of management on both states and changes.

In this project the maps are used in combination with more than 100k forest inventory plots, extensive targeted field sampling over two years and remote sensing to understand, (i) changes in remotely sensed greening since 1984, and (ii) differences in carbon storage. We will present and discuss preliminary and more mature results that suggests that (i) primary forests have greened considerably since 1984, and at mature ages, faster than managed forests do, and (ii) store considerably more carbon than the paired managed forests do. 
MALMI: towards combining machine learning and waveform migration for fully automated earthquake detection and location
Authors: Shi Peidong , Grigoli Francesco , Lanza Federica , Wiemer Stefan
Published: March 2022

Automatic event detection and location is key to real-time earthquake monitoring. With the increase of computing power and labeled data, automated workflows that utilize machine learning (ML) techniques have become increasingly popular; however, classical workflows using ML as phase pickers still face challenges for seismic events of short inter-event time or low signal-to-noise ratio (SNR). Full waveform methods that do not rely on phase pick and association are suitable for processing these events, but are computationally costly and can lack clear event identification criteria, which is not ideal for real-time processing. To leverage the advantages of both methods, we propose a new workflow, MALMI, which integrates ML and waveform migration to perform automated event detection and location. The new workflow uses a pre-trained ML model to generate continuous phase probabilities that are then back-projected and stacked to locate seismic sources using migration.

We applied the workflow to a microseismic monitoring dataset collected in a borehole at the Utah FORGE geothermal laboratory site. The proposed workflow can automatically detect and locate induced microseismic events from continuous geophone recordings. Different ML models are evaluated for detection capability and phase classification accuracy. We expect that better performance should be possible if a customized ML model re-trained using local dataset would be used in the MALMI workflow. Further comparison with conventional migration methods confirms that MALMI can produce much clearer stacked images with higher resolution and reliability, especially for events with low SNR. The workflow is freely available on GitHub, providing a complementary tool for automated event detection and location from continuous data.
An integrated approach for environmental multi-source remote sensing
Authors: Marsella Maria , Celauro Angela , Moriero Ilaria
Published: March 2022

 

Remote sensing measurements have benefited from a great technological improvement, which has allowed a higher degree of automation while increasing spatial and temporal resolution of the collected data. Multi-     scale and multi-frequency optical and radar satellite sensors, often adopted in an integrated manner, are starting to provide efficient solutions for controlling and monitoring rapidly evolving urban and natural areas. On the other hand, close range remote-sensing techniques, such as operated by UAV platforms, and innovative ground-based instruments offer, respectively, the chance to downscale the observation performing site-specific analysis at an enhanced resolution and to collect in-situ dataset for calibration and data quality. By improving the quantity and quality of the collected data, a better understanding of the in-going processes is possible and the setting up of a numerical forecast model for future scenarios.

 

Therefore, implementation of integrated techniques for environmental monitoring turns out to be a strategic solution to analyze hazardous areas at different spatial and temporal resolution. Research devoted to the optimization of data processing tools by means of AI algorithms has evolved with the aim of improving the level of information and its reliability. In this context, a great impact is linked to the availability of open data and open-source processing tools distributed after the Copernicus Program.

 

A review of the available technologies for environmental monitoring is provided including examples on experimental cases in areas affected by natural hazards (volcanic eruptions, landslides, coastal erosion, flooding, etc.) and human activities that can produce incidental damages on the environment (urbanization, agriculture, infrastructures, landfills, dumpsites, pollutions, etc.). In addition, the same approach is useful for monitoring the degradation of the cultural heritage sites. Finally, the capability of collecting fat at a global level contributed to the analysis of environmental and economic impacts consequent the Covid-19 pandemic.

 
Local surface heterogeneity and terrain drive disagreement between measured and modeled fluxes in the cloud-free Arctic stable boundary layer
Authors: Huss Jannis-Michael , Thomas Christoph
Published: March 2022

Our physical understanding of boundary-layer processes, particularly under the long-lived stable conditions of the polar night, is limited. In these weak-wind stable boundary layers, the exchange of energy, momentum, and matter, can be dominated by submeso-scale motions on scales larger than those of classical turbulence, which have been found to violate assumptions of local similarity concepts.

We investigated (1) whether the magnitude of non-local flux contributions, possibly arising from submeso-scale motions in concert with terrain, is systematically connected to certain boundary-layer states and flow directions, and (2) to what extent non-local forcings impact  turbulent heat fluxes as well as the local surface energy balance including advection.

Data were collected during the NYTEFOX (NY Alesund TurbulencE Fiber-Optic eXperiment) field campaign 2020 at the scientific AWIPEV Arctic station in Ny-Ålesund, Svalbard at the end of polar night. Non-local influences were detected and quantified by comparing the measured sensible heat flux from sonic anemometry to the flux modeled from local first-order closure using temperature profile observations from fiber-optic distributed sensing. The spatial structure of the time-variant flow and of the horizontal advection were computed from a unique set of observations from a large horizontal fiber-optic distributed sensing array spanning hundreds of meters.

First results indicate an influence of cloud cover with stronger non-local flux contributions during clear skies causing an increased radiative cooling of the surface. Additionally, such contributions were generated and/or guided by the heterogeneous terrain in the source area of the incoming flow. Steep mountain slopes caused very cold katabatic currents and, hence, promoted vertical decoupling. This resulted in stronger non-local impact on the local fluxes, causing large disagreement between modeled and measured sensible heat fluxes. The conditions featuring large non-local flux contributions were also associated with large magnitudes of horizontal advection of sensible heat.

Advection, as well as conditions that promote strong surface-based inversions, appear to cause an increased violation of the assumption of local similarity in the Arctic weak-wind stable boundary layer.
New zircon U-Pb geochronology from the Ketilidian orogen of South Greenland
Authors: Vestergaard Rikke , Waight Tod , Petersson Andreas , Jeon Heejin , Whitehouse Martin
Published: March 2022

The Paleoproterozoic Ketilidian orogen in South Greenland (1.85-1.73 Ga) is interpreted to be the result of northwards-dipping oblique subduction of an oceanic plate beneath the Archaean continental crust of the North Atlantic Craton. The Ketilidian orogen was part of the subducted-related magmatism and accretionary orogenic belt named the Great Paleoproterozoic Accretionary Orogen that existed along an active margin stretching through Laurentia (North America and South Greenland) to Baltica (Northeast Europe), which formed the supercontinent Columbia/Nuna. Thus, the orogeny represents part of an important episode of crustal growth and preservation in Earth’s history. The Central Domain of the orogeny is dominated by the plutonic remnants of a magmatic arc (the Julianehåb Igneous Complex (JIC), ca. 1.85-1.80 Ga), which eventually grew sufficiently large and stable to subsequently uplift and unroof, to produce rocks interpreted to represent erosional fore-arc deposits that are preserved to the south in the Southern Domain. Between ca. 1.80 Ga and 1.76 Ga, the fore-arc was subjected to metamorphism of amphibolite to granulite facies, and was subsequently intruded by post-tectonic granites (including rapakivi variants) of the Ilua Suite (1.75-1.73 Ga). We present new zircon U-Pb SIMS ages for granitic and metasedimentary rocks sampled at a regional scale in a traverse stretching NW to SW through the Central and Southern Domains of the Ketilidian Orogen in South Greenland. Previous studies have distinguished two pulses of magmatism in the JIC, an early event at ca. 1.85-1.83 Ga and a later phase at ca. 1.80-1.78 Ga. Our JIC samples are dominated by the late stage (<1.83 Ga) with most ages concentrated at 1.8 Ga, suggesting that the main volume of crust in the western portion of the arc was generated over a relatively short period. Ages for the Ilua Suite agree well with previous studies. Zircon age distributions in the metasedimentary rocks of the Southern Domain are consist with detritus dominantly sourced from the JIC, however the presence of small populations of older zircons (up to 2.8 Ga) not observed as inherited zircons in the JIC, indicates that older crustal components also eroded into the fore-arc. These U-Pb zircon results are part of an ongoing larger investigation combining O-Hf isotope compositions in zircon, coupled with whole rock geochemical and isotope data. This research will provide the first thorough geochemical and petrogenetic investigation of the timing, across arc variations, and source components involved in the formation and evolution of South Greenland as well as its contribution in one of the worldwide peaks of continental crustal growth.
The response of the Larsen C Ice Shelf to changes in ice-shelf buttressing
Authors: Mitcham Tom , Gudmundsson G. Hilmar , Bamber Jonathan L.
Published: March 2022

The future viability of the Larsen C Ice Shelf (LCIS) has been called into question following the collapse of its more northerly, neighbouring ice shelves on the Antarctic Peninsula, and the calving of the A68 iceberg in July 2017. Initially, using the ice-flow model Úa, we conduct time-independent experiments and find that the vast majority of the buttressing capacity of the LCIS is generated in the regions of the ice shelf just downstream of the grounding line. We also find that the Bawden and Gipps Ice Rises provide a negligible proportion of the total buttressing capacity of the ice shelf, as determined by modelled instantaneous changes in grounding line flux (GLF) in response to their removal.

We then conduct time-dependent experiments to examine the transient evolution of the LCIS and its tributary glaciers to changes in ice-shelf buttressing. We present, for the first time, simulations of the transient response of the system to the loss of basal contact at the Bawden and Gipps Ice Rises.  We find that the instantaneous increase in ice-shelf velocities is sustained throughout the 100-year model run, with associated dynamic thinning of the ice shelf on the order of tens of metres during this period. However, we find that the impact on the grounded ice dynamics, GLF and ice volume above flotation (VAF) is limited.

Through idealised calving experiments we show that the instantaneous response in GLF to a reduction in ice-shelf buttressing decays rapidly in the first few years following the calving event. We also find an increasing, but non-linear, relationship between the reduction in ice-shelf buttressing and the loss of VAF after 100 years, largely controlled by the bedrock topography of the tributary glaciers. With our model setup, using the BedMachine Antarctica v2 ice thickness and bedrock topography data, we find that the dynamic mass loss 100 years after the complete collapse of the LCIS is ~0.6 mm SLE.
Magnetic field fluctuations in CME-driven sheath regions
Authors: Kilpua Emilia , Good Simon , Ala-Lahti Matti , Osmane Adnane , Fontaine Dominique , Pal Sanchita , Räsänen Juska , Bale Stuart , Zhao Lingling , Hadid Lina , Janvier Miho , Yordanova Emiliya
Published: March 2022

The sheath regions driven by coronal mass ejections (CMEs) are large-scale heliospheric structures where magnetic field fluctuations are observed over various temporal scales. Their internal structure and nature of embedded  fluctuations are currently poorly understood. We report here the key characteristics of  magnetic field fluctuations in CME-driven sheaths, including their spectral index, intermittency, amplitude and compressibility. The results highlight the gradual formation of sheaths over several days as they propagate through interplanetary and the presence of intermittent coherent structures such as strong current sheets. The Jensen-Shannon permutation entropy and complexity analysis suggest that sheath fluctuations are stochastic, but have lower entropy and higher complexity than the preceding wind.  We also show the analysis results during the slow sheath at ~0.5 AU detected by Parker Solar Probe, highlighting that slow CMEs can have prominent sheaths with distinct fluctuation properties. 
Effect of biofilm permeability on flow and transport in three-dimensional porous media: A geostatistical study
Authors: Markale Ishaan , Carrel Maxence , Kurz Dorothee , Morales Veronica , Holzner Markus , Jimenez-Martinez Joaquin
Published: March 2022

Bacterial biofilms can form in porous media that are of interest in industrial and particularly environmental applications such as in situ groundwater remediation. The presence of biofilms modifies pore-scale and bulk hydrodynamics and consequently solutes transport and reaction kinetics. Porous media consist of highly heterogeneous flow fields and thus biofilm growth is also highly variable resulting in spatially variable biofilm permeabilities. Random processes are often invoked in hydrogeology to model variable quantities. Geo-statistical simulations require numerous realizations of a stochastic process over a grid. Our study leverages highly resolved three-dimensional X-ray computed microtomography images of bacterial biofilms in a tubular reactor to numerically compute pore scale flow and solute transport on a fine grid by considering various realizations of the biofilm permeability field. Using a conservative tracer experiment we first validate our flow and transport model which is then used to understand the impact of a heterogeneous permeability field on fluid-fluid and biologically driven reactions.
Identifying geographical patterns of transient deformation in the geological sea level record
Authors: Simon Karen M. , Riva Riccardo E. M. , Broerse Taco
Published: March 2022

In this study, we examine the effect of transient mantle creep on the prediction of glacial isostatic adjustment (GIA) signals. Specifically, we compare predictions of relative sea level change from GIA from a set of Earth models in which transient creep parameters are varied in a simple Burgers model to a reference case with a Maxwell viscoelastic rheology. The model predictions are evaluated in two ways: first, relative to each other to quantify the effect of parameter variation, and second, for their ability to reproduce well-constrained sea level records from selected locations. Both the resolution and geographic location of the relative sea level observations determine whether the data can distinguish between model cases. Model predictions are most sensitive to the inclusion of transient mantle deformation in regions that are near-field and peripheral relative to former ice sheets. This sensitivity appears particularly true along the North American west coast in the region of the former Cordilleran Ice Sheet, which experienced rapid sea-level fall following deglaciation between 14-12 kyr BP. Relative to the Maxwell case, Burgers models better reproduce this rapid phase of regional postglacial sea level fall. As well, computed goodness-of-fit values in this region show a clear preference for models where transient deformation is present in the whole or lower mantle, and for models where the rigidity of the Kelvin element is weakened relative to the rigidity of the Maxwell element. In contrast, model predictions of relative sea-level change in the far-field show little or weak sensitivity to the inclusion of transient deformation.
Spatial and Temporal Variation of Hydrological Risk in Rural and Urban Environmental Justice Communities
Authors: Sharkus Cielo , Givens Jennifer , Saia Sheila , Knighton James , Guzman Christian
Published: March 2022

The compounding effects of climate change are inextricably linked to social vulnerabilities, poverty, race, and systemic injustices. The intersection between climate change and risk manifests as geospatial environmental hazards such as flooding, which have been projected to increase over the next 30 years in the continental United states. These climate-driven increases suggest that even modest increases in flood hazards have the potential to impact traditionally marginalized communities vulnerable to flooding. Compositional characteristics such as social status and identity have been shown to be linked to increased mortality, and slower economic and physical recovery after flooding (e.g., Hurricane Harvey and Hurricane Ida). These patterns demonstrate that higher clustering of minorities and low socioeconomic status people face unequal social consequences of climate-related disasters. While continental-scale flood models have shown heightened hazard susceptibility, multiple dimensions of social characteristics—including spatial and temporal scales of social class and status—are needed to understand the granular differences between zip codes. To examine the relationship between spatial and temporal social and geographic scales, we compared the spatial clustering from 2010 to 2019 for two different indices of social vulnerability: Social Vulnerability Index (SVI) of the Centers for Disease Control and Prevention and the Environment Justice Index (EJ) of the Massachusetts Executive Office of Energy and Environmental Affair. Between 2010 and 2019 in Massachusetts, we evaluate whether greater flood protections exist in urban communities (average 2019 population: 244,422) vs rural communities (average population: 8,310) and if flood risks change over time for minority populations. The results of this study demonstrate that current hydrologic extremes are disproportionately contained within block groups of vulnerable populations (e.g., 40.5% of vulnerable block groups intersect with the 500-year flood area and 20.7% for the 100-year flood area for Lawrence for example) and that social vulnerability to flood risk is increasing in rural areas with higher amounts of EJ block groups, while decreasing in urban areas with diversifying EJ block groups. Furthermore, the increased detail provided in EJI census block group scale (as compared to SVI census tract scale) demonstrated distinct zones that would require increased disaster management planning and prioritization.
Estimating the Geoelectric Field, Transmission Line Voltages, and GICs During a Geomagnetic Storm in Alberta, Canada
Authors: Cordell Darcy , Unsworth Martyn , Lee Benjamin , Hanneson Cedar , Milling David , Parry Hannah , Mann Ian
Published: March 2022

Estimating the effect of geomagnetic disturbances on infrastructure is an important problem since they can induce damaging currents in electric power transmission lines. In this study, an array of magnetotelluric (MT) impedance measurements in Alberta and southeastern British Columbia are used to estimate the geoelectric field resulting from a magnetic storm on September 8, 2017. The resulting geoelectric field is compared to the geoelectric field calculated using the more common method involving a piecewise-continuous 1-D conductivity model. The 1-D model assumes horizontal layers, which result in orthogonal induced electric fields while the empirical MT impedance data account for fully 3-D electromagnetic induction. The geoelectric field derived from empirical MT impedance data demonstrates a preferential polarization in southern Alberta, and the geoelectric field magnitude is largest in northeastern Alberta where resistive Canadian Shield outcrops. The induced voltage in the Alberta transmission network is estimated to be ~120 V larger in northeastern Alberta when using the empirical MT impedances compared to the piecewise-continuous 1-D model. Transmission lines oriented northwest-southeast in southern Alberta have voltages which are 10-20% larger when using the MT impedances due to the polarized geoelectric field. As shown with forward modelling tests, the polarization is due to the Southern Alberta British Columbia conductor in the lower crust (20-30 km depth) that is associated with a Proterozoic tectonic suture zone. This forms an important link between ancient tectonic processes and modern-day geoelectric hazards that cannot be modelled with a 1-D analysis. The geoelectric field model and resulting line voltage is compared to differential magnetometer GIC measurements on one transmission line near the Heartland transformer in northeastern Alberta.
Surface soil moisture in sub-seasonal to seasonal (S2S) prediction driven by a hybrid model over drought-prone regions
Authors: Wang Xiaoyi
Published: March 2022

The prediction skill of the S2S period (usually referred to as two weeks but less than a season) always suffers from the integrated influence between weather and climate. Although S2S prediction has attracted more attention than before and multiple efforts have prompted related studies, the accuracy of surface soil moisture prediction in the dry condition is generally inferior to that of other variables in the S2S period. This study proposes a framework combing an ensemble empirical mode decomposition (EEMD) and Multilayer perceptron (MLP) to predict the surface soil moisture (0-7 cm) in two drought-prone regions. The proposed method has been verified and optimized in the Netherlands and Spain by using hindcasts driven by ERA5 reanalysis which can be regarded as a proxy for the real weather. The concrete practice consists of 1) calculating intrinsic mode functions (IMFs) collection and their residual components of selected ERA5-Land variables that are sensitive to surface soil moisture after data pre-processing, 2) similar IMFs curves classifications, 3) further feature selection according to classified sets, and 4) performing IMFs-driven MLP daily predictors and integrating the predicted IMFs and residual components to obtain the predicted surface soil moisture. The positive results show that this framework can be served as a regional S2S forecasting approach based on ERA5-Land reanalysis data, and with an expected daily ERA5-Land update of 5 days behind real time in 2022 instead of the current 3-month latency, the employed hybrid model is anticipated to explore realistic hydrological and agricultural applications.
Algorithms fusion for near-surface geophysical survey
Authors: Jeng Yih , Chen Chih-Sung , Yu Hung-Ming
Published: March 2022

The near-surface geophysical methods have been widely applied to investigations of shallow targets for scientific and engineering research. Various data processing algorithms are available to help visualize targets, data interpretation, and finally, achieve research goals.

Most of the available algorithms are Fourier-based with linear stationary assumptions. However, the real data are rarely the case and should be treated as nonlinear and non-stationary. In recent decades, a few newer algorithms are proposed for processing non-stationary, or nonlinear and non-stationary data, for instance, wavelet transform, curvelet transform, full-waveform inversion, Hilbert-Huang transform, etc. This progress is encouraging, but conventional algorithms still have many advantages, like strong theoretical bases, fast, and easy to apply, which the newer algorithms are short of.

In this study, we try to fuse both conventional and contemporary algorithms in near-surface geophysical methods. A cost-effective ground-penetrating radar (GPR) data processing scheme is introduced in shallow depth structure mapping as an example. The method integrates a nonlinear filtering technique, natural logarithmic transformed ensemble empirical mode decomposition (NLT EEMD), with the conventional pseudo-3D GPR data processing methods including background removal and migration to map the subsurface targets in 2D profile. The finalized pseudo-3D data volume is constructed by conventional linear interpolation. This study shows that the proposed technique could be successfully employed to locate the buried targets with minimal survey effort and affordable computation cost. Furthermore, the application of the proposed method is not limited to GPR data processing, any geophysical/engineering data with the similar data structure are applicable.
The role of a Mediterranean Sea eddy in the January 2020 flooding in Israel
Authors: Strobach Ehud , Klein Patrice , Ziv Baruch
Published: March 2022

On January 8, 2020, an extreme storm event took place in the Eastern Mediterranean Sea, during which 100-130mm of rain fell in the northern part of Israel in one day. The heavy precipitation event resulted in seven deaths and damages to homes, vehicles, and infrastructure. At the same time, about 100km to the west of northern Israel, the sea was characterized by a mesoscale eddy with a warm core. In recent years, it was established that small-scale sea features affect the atmosphere above and synoptic-scale circulation patterns, including long-term rainfall. However, it is still unclear how these features may affect the propagation and intensity of individual storms, such as the January 8, 2020 storm event.

Recently, the WRF (The Weather Research and Forecasting) atmospheric model was coupled with the ocean model MITgcm (MIT general circulation model). The coupled model was named the SKRIPS (Scripps–KAUST Regional Integrated Prediction System) model. The two SKRIPS model components (WRF and MITgcm) are well tested at high resolutions, and the regionality of the coupled model allows us to isolate local features while maintaining the large-scale circulation as observed.

In this talk, I will present results from a high-resolution (~5km) coupled atmosphere-ocean regional simulation using the SKRIPS model performed during the January 8, 2020 event. The importance of the sea eddy in determining the storm intensity and propagation will be discussed, elaborating on the role of air-sea coupling and the model resolution. Understanding the effect of such small-scale sea features on extreme atmospheric events may improve their representation in weather and climate models, extending models prediction skill.
Tools for sharing and evaluating the CHAOS geomagnetic field model and the shc-file format for time-dependent spherical harmonic models
Authors: Kloss Clemens , Finlay Christopher C. , Olsen Nils
Published: March 2022

Geomagnetic field models are essential in the study of the physical processes that contribute to the Earth’s magnetic field. There are several groups that build models of the Earth’s magnetic field. These models essentially differ in the magnetic data and mathematical methods used during the model estimation, and in the represented sources of the geomagnetic field. It is then the users who choose the models that are most suitable for the study of the geophysical signals of interest. However, there is currently no single platform where field models are collected in a standardised way, and that provides information which helps users to find the best models for their purposes.

Here, we present the geomagnetic field model called CHAOS that is developed and regularly updated by the Technical University of Denmark. CHAOS provides estimates of the recent time-dependent and static internal magnetic fields, and the external magnetospheric field during quiet geomagnetic conditions. It is derived from magnetic data collected by the Swarm, CHAMP, Ørsted, SAC-C, CryoSat-2 satellite missions supplemented by ground observatory data. It is updated approximately every 4 months with the latest ground and satellite data; the current version CHAOS-7.9 covers the time from 1997 to November 2021.

The model is distributed in various formats. For the time-dependent internal field, B-spline coefficients for each spherical harmonic are provided in a similar format as traditionally used for the gufm1 historical field model and the CALS7K millennial timescale models. It is also provided in the shc-file format, which was developed and adopted for distributing spherical harmonic models determined in connection with the Swarm magnetic satellite mission. This format allows reconstruction of spline-based models from a dense sampling of the time series of the spherical harmonic coefficients and is easier for non-experts to use. A piecewise polynomial Matlab version is also available. For reading and evaluating the CHAOS model, we provide Fortran, Matlab and Python software. In particular, we have recently developed the ChaosMagPy Python package, which allows the CHAOS model (and other spherical harmonic field models) to be easily evaluated and visualized.

Although the shc-file format and ChaosMagPy have been developed primarily in support of the Swarm mission and the CHAOS model, they can be used more broadly for time-dependent spherical harmonic field models or serve as a starting point for the development of new tools that enable cross-disciplinary sharing of data and models.
Application of information theoretical measures for improved machine learning modelling of the outer radiation belt
Authors: Papadimitriou Constantinos , Balasis Georgios , Daglis Ioannis A. , Wing Simon
Published: March 2022

In the past ten years Artificial Neural Networks (ANN) and other machine learning methods have been used in a wide range of models and predictive systems, to capture and even predict the onset and evolution of various types of phenomena. These applications typically require large datasets, composed of many variables and parameters, the number of which can often make the analysis cumbersome and prohibitively time consuming, especially when the interplay of all these parameters is taken into consideration. Thankfully, Information-Theoretical measures can be used to not only reduce the dimensionality of the input space of such a system, but also improve its efficiency. In this work, we present such a case, where differential electron fluxes from the Magnetic Electron Ion Spectrometer (MagEIS) on board the Van Allen Probes satellites are modelled by a simple ANN, using solar wind parameters and geomagnetic activity indices as inputs, and illustrate how the proper use of Information Theory measures can improve the efficiency of the model by minimizing the number of input parameters and shifting them with respect to time, to their proper time-lagged versions.
Application of electric fields to mitigate inhibition on anammox consortia under long-term tetracycline stress
Authors: Cheng Benai
Published: March 2022

Anaerobic ammonium oxidation (anammox) has been recognized as a promising microbial denitrification technique in recent years,duing to  the treatment of high-strength ammonium wastewater. Compared to typical nitrification and denitrification methods, the anammox process transforms ammonium  and nitrite to nitrogen gas , and saves up to 60% of energy on aeration, sludge disposal and organic carbon addition. Furthermore, the process reduces greenhouse gas emissions by more than 25%, particularly in the production of nitrous oxide (N2O). However, the anaerobic ammonia oxidation bacteria (AnAOB) are very sensitive and vulnerable to many inhibitors, especially antibiotics in wastewater. In this study, the feasibility of applying electric fields to mitigate inhibition of tetracycline (TC) on anammox process and improve system stability was evaluated. Three electric field intensities of 1, 3 and a variable intensity of 1-6 V (VEF) were used to optimize electric field intensity under gradually increasing addition of TC (0.5, 2 and 10 mg·L-1). Results showed that the application of electric fields (3 V and VEF) could improve TC tolerance and keep relatively high-efficiency nitrogen removal performance, especially at TC ≥ 2 mg·L-1. Furthermore, applying electric fields contributed to mitigate irreversible inhibition and improve the stability of community structure. Underlying mechanism analysis indicated that the main mechanism of applying electric fields to mitigate inhibition relies on sludge structure strengthening. This study explored a novel strategy to reduce the inhibition of antibiotics on microbial denitrification and broaden the application of anammox in industrial water treatment.
Fast and automatic measurement of grain geometries from 3D point clouds
Authors: Guerit Laure , Steer Philippe , Lague Dimitri , Crave Alain , Gourdon Aurélie
Published: March 2022

The size distribution of sediments together with their shape inform on their transport history, are important factors controlling the efficiency of erosion and transport, and control the quality of aquatic ecosystems. However, the size distribution of sediments is generally assessed using poorly representative field measurements and determining the grain-scale shape of sediments remains a real challenge in geomorphology. To tackle this issue, we develop a new methodological approach based on the segmentation and geomorphological fitting of 3D point clouds. Point cloud segmentation into individual grains is performed using a watershed algorithm applied here to 3D point clouds. Once the grains are individualized into several sub-clouds, the morphology of each grain is determined by fitting a 3D ellipsoid to each sub-cloud. These 3D models are then used to extract the size distribution and the grain-scale shape of the sediment population. The algorithm is validated against field data acquired by Wolman counts in coastal and fluvial environments. The main benefits of this automatic and non-destructive method are that it provides, with a fast and efficient approach, access to 1) an un-biased estimate of surface grain-size distribution on a large range of scales, from centimeters to tens of meters; 2) a very large number of data, only limited by the number of grains in the point-cloud dataset; 3) the 3D morphology of grains, in turn allowing to develop new metrics characterizing the size and shape of grains; and 4) the in-situ orientation and organization of grains and grain clusters. The main limit of this method is that it is only able to detect grains with a characteristic size significantly greater than the resolution of the point cloud.
CycloNet: European Cyclostratigraphy Network
Authors: Claeys Philippe , Sinnesael Matthias , De Vleeschouwer David , Zeeden Christian
Published: March 2022

The study of astronomical climate forcing and the application of cyclostratigraphy experienced a spectacular growth over the last decades. In 2018, the first Cyclostratigraphy Intercomparison Project (CIP) workshop constituted the first attempt to compare different methodological approaches and unite the global community around standard, uniform and reliable procedures. Two major conclusions were: [1] There is a need for further organization of the cyclostratigraphic community (e.g. to streamline different methodologies); [2] Cyclostratigraphy is a trainable skill, but currently many universities lack specific resources for training and education. Today, a regular newsletter, a dedicated free open-access journal “Cyclostratigraphy and Rhythmic Climate Change (CRCC)”, a scientific podcast titled CycloPod, and an educational website “www.cyclostratigraphy.org” connect the cyclostratigraphy community. The newly created CycloNet (Research Foundation Flanders FWO Funding) expands this effort into a real and sustainable scientific research network with partners from all around Europe, and open to the global community. At the same time, CycloNet creates a platform for streamlining and integrating new multi-disciplinary approaches. The main scientific targets for CycloNet in the next five years are: [1] Set up a diverse and sustainable community structure, relying on exchange, interaction and training, [2] Boost research by novel methodological approaches applying advanced signal processing techniques, [3] Organize a second Cyclostratigraphic Intercomparison Project. With this poster, we reach out to the broader community to exchange ideas on concepts and activities that CycloNet can help to develop further towards the future.
Evaluation of riprap failure impact on the downstream scour hole
Authors: Fliszar Robert , Gilja Gordon
Published: March 2022

Scouring around bridge piers is considered to be a significant process in rivers because it can alter bridge loading and consequently its stability. Riprap is often deployed as scour countermeasure, and while it does protect the pier from local scouring, it doesn’t completely solve the scouring problem because it deflects the scour hole downstream of the bridge. Riprap is flexible, and flood events can induce five significant failure mechanisms - shear, edge and winnowing failure under clear-water conditions and bedform-induced and bed-degradation-induced failure under live-bed conditions. On the other hand, the thick riprap layer can withstand a partial failure of the layer with the capability of armouring the scour hole. This paper investigates the mechanisms of riprap partial collapsing and its effects on the development of a downstream scour hole. Experiments were conducted on the physical model of scouring around bridge piers protected with riprap built in the Department of Hydroscience and Engineering laboratory under the University of Zagreb. Experimental setup included different pier shapes (rectangular and circular piers) in order to examine the influence of the pier as well as the influence of riprap geometry in different flow conditions.

Acknowledgments

This work has been supported in part by Croatian Science Foundation under the project R3PEAT (UIP-2019-04-4046).
Drivers of hydrological model diversity and model selection factors - The example of Switzerland.
Authors: Horton Pascal , Schaefli Bettina , Kauzlaric Martina
Published: March 2022

Hydrological models are fundamental tools that play a key role in many areas of hydrological science and climate change impact studies. However, it is well known that the number of models has increased beyond what is necessary. One of the key drivers for model diversity in hydrology is the wide range of model applications, motivated by specific needs and contexts that require suitable models. Yet, a significant part of this diversity is not driven by the context, as different models are applied under analogue circumstances.

To better understand the main drivers of model diversity, a review of hydrological modelling habits was conducted on studies carried out in Switzerland. Despite being a small country, Switzerland has a variety of hydro-climatological regimes, water resource management challenges, and hydrological research institutes, and can thus be representative of other regions. A first observation was that the motivations for selecting a model are rarely stated in scientific articles, and the adequacy of the model for the context or landscape is often not addressed. Thus, a survey was conducted to evaluate some subjective aspects that are otherwise difficult to retrieve from the scientific literature.

Not surprisingly, researchers are very keen on using a model developed at their own institute, which provides the benefit of expertise and efficiency, but at increased risk of context inadequacy and automatism in decisions. Other aspects were considered relevant in the model selection process, such as – indeed – adequacy, access to the code, reuse of existing model setups, collaborations, technical constraints or data availability.

Several hydrological models exist in Switzerland, while the vast majority of the studies were conducted using a single model. To some extent, model diversity is desirable to assess model variability, but multi-model applications to harness this diversity are largely missing. The survey could highlight that most researchers consider multi-model approaches important, but most do not apply them for various practical reasons, such as lack of resources (time and/or money) or lack of expertise in another model. We believe that some barriers can be lowered to facilitate multi-model approaches, requiring efforts from the modelling community and the funding agencies.
A new method for the attribution of breakpoints in segmentation of IWV difference time series 
Authors: Nguyen Khanh Ninh , Bock Olivier , Lebarbier Emilie
Published: March 2022

In recent years, the detection and correction of the non-natural irregularities in the long climatic records, so-called homogenization, has been studied. This work is motivated by the problem of identification of origins of the breakpoints in the segmentation of difference series (difference between a candidate series and a reference series). Several segmentation methods have been developed for the difference series, but many of them assume that the reference series is homogenous. However, the homogeneity of the reference series, in reality, is uncertain and unproven. In our study, we applied the segmentation method GNSSseg (Quarello et al., 2020) on the difference between the Integrated water vapour estimates of the CODE REPRO2015 GNSS data set and the ERA5 reanalysis. About 36.5% of change points can be validated from the GPS metadata, and the origins of the remaining 64.5% are questionable (Nguyen et al., 2021). The ambiguity can be leveraged when there is at least one nearby GPS station with respect to which the candidate series can be compared. The proposed method uses weighted t-tests combining the candidate GPS and ERA series and their homologues (denoted GPS' and ERA') from each nearby station. If sufficient consistency emerges from the six tests for all the nearby stations, a decision can be made whether the breakpoint detected in the candidate GPS-ERA series is due to GPS or, alternatively, to ERA. For each quadruplet (GPS, ERA, GPS', ERA'), six t-tests are performed, and the outcomes are combined. In a set of 81 globally distributed GNSS time series spanning more than 25 years, 56 series have at least one nearby station, where 171 breakpoints are detected in segmentation, in which 136 breakpoints are attributed to the GPS. Among those, 94 breakpoints have consistent results between all the nearby stations. GPS-related breakpoints are used for the correction of the mean shift in the difference series. The impact of the breakpoint correction on the GNSS IWV trend estimates is then evaluated. 

Quarello A, Bock O, & Lebarbier E. (2020). A new segmentation method for the homogenisation of GNSS-derived IWV time-series. arXiv: Methodology.

Nguyen KN, Quarello A, Bock O, Lebarbier E. Sensitivity of Change-Point Detection and Trend Estimates to GNSS IWV Time Series Properties. Atmosphere. 2021; 12(9):1102. https://doi.org/10.3390/atmos12091102
Integrated surface and subsurface hydrological modelling to support the assessment of the vulnerability of surface water supplies.
Authors: Gatel Laura , Tremblay Yohann , Therrien René
Published: March 2022

The protection of water resources is a challenging task and requires a detailed understanding of surface water and groundwater dynamics and interactions. Integrated groundwater and surface water models represent useful tools to assess how groundwater affects the quantity and quality of surface water, which is often a source of drinking water. It is the case for the City of Quebec, Canada, where surface water is the only source of drinking water and where water managers must assess its vulnerability to contamination and depletion. This work focuses on the Nelson River catchment (70 km2), located within the larger catchment of the main drinking water source in Quebec City. The objective is to quantify the links between groundwater and surface water with the 3D integrated hydrological model HydroGeoSphere and simulate coupled surface/subsurface water flow and contaminant transfer. The Nelson catchment model has been calibrated to reproduce observed surface discharges and water table level measurements. Coupled surface water and groundwater flow is then simulated over multiple years using daily meteorological data. Output variables such as distributed infiltration, preferential flow pathways, inter-seasonal changes of surface water volumes, unsaturated and saturated groundwater volumes, are analysed to assess the link between surface water and groundwater. Since this urban area is undergoing growing urbanisation, future scenarios of urban development are also simulated to evaluate the impact of soil sealing on surface/groundwater interactions. The understanding of surface/subsurface interactions in this particular context aims at assessing the vulnerability of the surface drinking water source.