bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatiotemporal Variability of Tropical Cyclone Induced Ocean Heat Uptake and Its Effect on Ocean Heat Content
Authors: Fan Kaigui , Wang Xidong , Shao Caixia
Published: March 2022

Tropical cyclone (TC) can pump heat downward through inducing intense vertical mixing. Many efforts have been made to estimate the magnitude of TC-induced ocean heat uptake (OHU), but the spatiotemporal variability of TC-induced OHU remains unclear. This study uses satellite-observed sea surface temperature (SST), subsurface temperature profiles, and turbulent heat fluxes to investigate the spatiotemporal variability of TC-induced OHU and its potential impacts on ocean heat content (OHC) during the period 1985-2018. It is found that category 3-5 TCs dominate the TC-induced OHU, accounting for ~70% of overall amount of TC-induced OHU globally each year. The time series of TC-induced OHU in global and regional oceans exhibit evident interannual-to-interdecadal variability, which is closely related to the TC power dissipation index (PDI). We further decompose PDI into TC intensity, frequency, and duration and find that category 3-5 TC frequency, annually averaged TC intensities, and durations all contribute to the variability of TC-induced OHU except that the averaged TC intensities have no significant relations with the TC-induced OHU in the North Indian Ocean, South Indian Ocean, and Southwest Pacific. In addition, the TC-induced OHU is shown to be responsive to equatorial SSTs rather than tropical SSTs, implying that the TC-induced OHU is modulated by El Niño-Southern Oscillation (ENSO). The TC-induced OHU might have the potential to influence OHC variability, particularly in the equatorial Pacific, where there is significant TC-induced OHU convergence. It has an important implication that TC-induced OHU might have potential effects on ENSO evolution.
Predicting the Transit Time and Geo-effectiveness of Coronal Mass Ejections using Neural Networks
Authors: Nedal Mohamed , Shalaby Heba , Mahrous Ayman
Published: March 2022

Predicting the arrival time of Coronal Mass Ejections (CME) and the strength of their geomagnetic storms at Earth is crucial in space operations and essential to avoid losing our space instruments and not to risk our astronauts’ lives in space. Besides, protecting the power grids and pipelines on the ground from the side effects of geomagnetic storms. We contribute to this matter by implementing Neural Network (NN) models to predict the CME transit time and the minimum value of the Disturbed storm time (Dst) index of the associated geomagnetic storm.

For the first time, we employed the planets' ephemeris as input features. Taking the CME properties (angular width, linear speed, speed at 20 solar radii, measurement position angle, latitude, and longitude), the solar wind and plasma parameters (the differential speed between the CME and the solar wind, the average interplanetary magnetic field with its 3D components, proton density and plasma temperature, speed in 3D components, dynamic pressure, electric field, plasma beta parameter, Mach number, and magnetosonic Mach number), and the planets' ephemeris in the solar system (distance from the Sun, latitude, and longitude) as inputs, we performed a grid of NNs to predict not only the CME transit time but also the minimum disturbed storm time (Dst) index of the associated geomagnetic storm.

We proposed the new Best-of-the-Best (BOB) approach to optimize the NN hyperparameters using the GridSearch method in Python. We assembled our dataset from (Gopalswamy et al., 2010), (Micha lek et al., 2004), and (Richardson and Cane, 2010) with a total of 230 events between 1997 and 2020. This is the largest dataset of CME-ICME pairs along with solar wind indices and planets locations in the solar system so far.

Remarkably, for the given dataset, the best set of input features for predicting the CME transit time was the CME features and the planets' ephemeris, while for predicting the Dst index were the top correlated features, with a Mean Absolute Error (MAE) of 13.54 hr and 35.57 nT, respectively. More details are described in the manuscript. 
Determination of the six unknowns of the paleostress tensor from vein data
Authors: Pascal Christophe , Jaques Luís , Yamaji Atsushi
Published: March 2022

The quantification of tectonic forces or, alternatively, stresses represents a significant step towards the understanding of the natural processes governing plate tectonics and deformation at all scales. However, paleostress reconstructions based on the observation and measurement of natural fractures are traditionally limited to the determination of four out of the six parameters of the stress tensor. In the present study, we attempt to reconstruct full paleostress tensors by extending the methodologies advanced by previous authors. We selected Panasqueira Mine, Central Portugal, as natural laboratory, and focused on the measurement of sub-horizontal quartz veins, which are favourably exposed in three dimensions in the underground galleries of the mine. Inversion of the vein data allowed for quantifying the respective orientations of the stress axes and the shape ratio of the stress ellipsoid. In order to reconstruct an additional stress parameter, namely pressure, we extensively sampled vein material and combined fluid inclusion analyses on quartz samples with geothermometric analyses on sulphide minerals. Finally, we adjusted the radius of the obtained Mohr circle with the help of mechanical parameters, and obtained the six parameters of the paleostress tensor that prevailed during vein formation. Our results suggests a NW-SE reverse stress regime with a shape ratio equal to ~0.6, lithostatic pore pressure of ~250 MPa and differential stress between ~40 and ~90 MPa.
Effect of CO2-rich water injection on the hydromechanical properties of Pont Du Gard limestone 
Authors: Vafaie Atefeh , Cama Jordi , M Soler Josep
Published: March 2022

CO2 storage in deep geological formations (e.g., saline aquifers) is essential for global warming mitigation. Storage of large amounts of CO2 in the saline aquifers results in acidification of the resident brine, inducing chemical reactions that change the pore structure of the host rock. Hence, the hydromechanical properties of the host rock are likely to alter, which affects the long-term injectivity and mechanical integrity of the reservoir.

To improve our understanding of the alteration of carbonate rocks after the injection of CO2, we have conducted percolation experiments under supercritical CO2 conditions. CO2-saturated water was injected at a constant rate of 0.15 mL/min through cylindrical core samples of Pont Du Gard limestone (diameter of 2.5 cm and length of ~5 cm) at 100 bar PCO2 and 60°C for 14 and 28 days. Fluid chemistry analyses were combined with X-ray microtomography imaging (XCMT) and porosity, permeability, and ultrasonic waves velocity (i.e., compressional and shear) measurements to assess the induced changes in rock properties.

Measured chemical parameters of the effluent solutions revealed rapid calcite dissolution correlating with 4% and 9.6% porosity enhancements for the 14-day and 28-day injections, respectively. Porosity enhancement affected mostly the inlet of the cores. Permeability increased by three orders of magnitude in both cases (from 10-14 to 10-11 m2). XCMT images disclosed that the substantial increase in permeability coincides with the formation of large wormholes along the cores, likely controlled by their intrinsic heterogeneity. Ultrasonic waves velocity measurements under ambient conditions demonstrated that the observed alterations in the pore structures degrade the mechanical stiffness of the rock by up to 40%. Our findings provide insight into the key role of natural heterogeneity in the reactivity of the rock and in the resulting evolution of its hydromechanical properties during CO2 storage.
Seismic Monitoring of Novaya Zemlya: Progress, Challenges, and Prospects
Authors: Kvaerna Tormod , Dando Ben , Gibbons Steven
Published: March 2022

The permanent seismic stations of the European Arctic maintain a detection threshold of around magnitude 2 for events on and around Novaya Zemlya. Events above magnitude 3 are clearly observed by multiple stations at regional and far-regional distances and, with improved traveltime models, can be located with high accuracy. The monitoring capability for smaller magnitude events is dominated by the small aperture seismic arrays ARCES and SPITS. We review the properties of Novaya Zemlya seismic signals on key stations and discuss how empirical signal processing may enhance detection and interpretation of future events in the region. We present a joint probabilistic location for 21 low magnitude events between 1986 and 2020 in which the joint probability distribution for all events simultaneously exploits both constraints on earlier events from stations no longer in operation and constraints on newer events from more recently deployed stations. Advances in signal processing, enhanced exploitation of archive data, new permanent stations, and comparative multiple event analysis will all contribute both to a more robust and sensitive detection capability and higher confidence in signal interpretation.
Using radio frequency signal classification to monitor explosive eruptive activity 
Authors: Behnke Sonja , Edens Harald , Theiler James , Swanson Diana , Senay Seda , Iguchi Masato , Miki Daisuke
Published: March 2022

Explosive volcanic eruptions often produce a repeatable pattern of electrical activity that can be exploited for volcano hazard monitoring. First, a swarm of small “vent discharges” occurs within the gas thrust region of the plume starting at the onset of an explosion. Vent discharges often persist for several seconds, depending on the duration of the explosion. In addition, vent discharges are known to occur in high-intensity explosions involving the fragmentation of fresh magma. Several seconds after the onset of an explosion, lightning starts to occur throughout the eruption column as charge begins to separate. This chronological sequence of vent discharges followed by lightning has been observed during eruptions from several different volcanoes, including Augustine Volcano, Redoubt Volcano, Eyjafjallajokull, and Sakurajima. In this presentation we demonstrate a proof-of-concept method for an eruption detection algorithm that exploits this common and repeatable pattern. The algorithm leverages a logistic regression classifier to distinguish between radio frequency waveforms of vent discharges and lightning. To demonstrate our method, we use broadband (20-80 MHz) very high frequency (VHF) waveform data of explosive volcanic eruptions from the Minamidake crater of Sakurajima volcano in Japan collected between May 2019 and May 2020. We show that individual VHF impulses produced by vent discharges and lightning can be accurately classified due to differences in the amount of signal clutter surrounding each type of impulse. In particular, we show that impulses from vent discharges are more isolated in time compared to impulses from lightning. The results of the signal classifier are then used to identify the characteristic pattern of volcanic electrical activity to determine if an explosive event has occurred. Implementation of the detection algorithm on an agile and deployable VHF sensor would engender a new method of volcano hazard monitoring, and help facilitate the research necessary to operationalize measurements of volcanic electrical activity in order to inform an eruption response.
Earthworm-plant-microbiota interactions
Authors: Hodson Mark , Brailey-Jones Phil , Burns Will , Harper Andrea , Hartley Sue , Helgason Thorunn , Walker Hannah
Published: March 2022

Earthworms have a positive effect on plant growth; this is typically attributed to increased N availability. Earthworms can also increase Si availability; plant Si plays a role in drought tolerance. Finally, earthworms effect microfaunal diversity. We conducted a glasshouse experiment to investigate interactions between these factors. Wheat varieties (Skyfall and four ancient strains) were grown in a greenhouse under presence / absence of adult Allolobophora chlorotica and no-drought / drought watering regimes (39 days watering then a further 17 days of watering or no watering).

Despite earthworm aestivation in drought treatments, plant growth was greater in both the no-drought and drought treatments.

Plant %N was greater in the watered treatments; for the drought treatments, it was greater in the earthworm-present treatments. Plant %C was greater in the earthworm-present treatments. In the earthworm-absent treatments Plant %P and %Si was greater in the watered treatments. In the watered treatments %P and %Si was greater in the absence of earthworms.

Soil pH (c. 8.1) was slightly decreased in the earthworm-present and in the watered treatments. The watered treatments contained more extractable nitrate. Extractable P showed no difference across treatments. The droughted earthworm-present treatments contained more extractable Si than both the earthworm-present watered treatments and earthworm-absent drought treatments.

Different wheat strains behaved similarly with Skyfall showing greater biomass and, sometimes, elemental concentrations.

Bacterial and fungal beta-diversity varied with both watering and earthworm treatments; fungal diversity also varied between wheat strains.

Plants showed significant differences in RNA expression between both watering and earthworm treatments including for genes linked to N uptake.

Earthworms promoted plant growth under both watered and drought conditions. Under drought conditions this does not appear to be related to Si availability or uptake. Similarly we observed no simple relationship between earthworm-presence, N (or P) and plant growth though under drought conditions the presence of earthworms promoted growth and %N in the plants despite lower extractable nitrate. The RNA response of plants suggests a N-related effect perhaps mediated by changes in microbial diversity.
COST-G: Status and recent developments
Authors: Jaeggi Adrian , Meyer Ulrich , Peter Heike , Teixeira Encarnacao Joao , Lasser Martin , Flechtner Frank , Dahle Christoph , Boergens Eva , Förste Christoph , Mayer-Gürr Torsten , Kvas Andreas , Behzadpour Saniya , Lemoine Jean-Michel , Bourgogne Stéphane , Koch Igor , Flury Jakob , Groh Andreas , Eicker Annette , Blazquez Alejandro , Meyssignac Benoit
Published: March 2022

Three years after its inauguration we draw a very positive résumé of the work of IAG’s Combination Service for Time-variable Gravity Fields (COST-G). The operational combination of GRACE-FO monthly gravity fields runs flawlessly. All seven associated and partner analysis centres timely provide high quality gravity fields, the COST-G quality control returns reliable noise and signal assessment based on meanwhile almost 4 years of GRACE-FO data, and the evaluation confirms the robustness and low noise level of the combined products.

COST-G is a highly dynamic service that is further developed in the frame of the Horizon2020 project Global Gravity-Based Groundwater Product (G3P) project, where an alternative accelerometer transplant product was developed, which in COST-G test combinations showed a very positive effect on the C30 gravity field coefficient and led to a general noise reduction in the medium to high degree range. Moreover, a deterministic signal model based on the monthly combinations has been released for the first time in September 2021 as a new COST-G product. It is updated quarterly with the most recent GRACE-FO data and aims to support operational precise orbit determination of low Earth orbiters. For the near future an extension of COST-G to also include analysis centres from China is envisaged and plans go to a revised combination of the reprocessed GRACE time-series.
Imaging the full extent of the Australian cratonic lithosphere using waveform tomography with massive datasets.
Authors: de Laat Janneke , Lebedev Sergei , Chagas de Melo Bruna , Celli Nicolas , Bonadio Raffaele
Published: March 2022

Australia has a long a complex geological history, spanning from the early Archean to the present day. Tomographic models can help us better understand the evolution of Australia by imaging the seismic structure of the crust and underlying mantle. We present a new S-wave tomographic model, Aus22, computed using a very large dataset of 0.9 million seismograms. The dataset includes all publicly available broadband data and yields the densest possible coverage across the hemisphere centred at the Australian continent, with sparser coverage elsewhere. Aus22 is computed using a three-step inversion procedure: 1. waveform inversion, 2. tomographic inversion and 3. outlier analysis. The model is validated by resolution tests and, for particular locations with notable differences with previous models, by independent inter-station measurements of surface-wave phase velocities. The new tomography resolves the structure of the Australian Plate and its boundaries in great detail. Cratonic lithosphere underlies nearly all of western and central Australia and shows substantial lateral heterogeneity. The highest seismic velocities are observed in the central-west portion of the continent, including the West and South Australian Craton. The North Australian Craton can be distinguished by a slightly lower seismic velocity, especially in its southern part. The cratonic lithosphere below the North Australian Craton extends northwards offshore through the Gulf of Carpentaria and the Arufa and Timor Sea and terminates at the southern Banda Arc and the New Guinea Fold-and-Thrust Belt, marking the northern boundary of the Australian Plate. The eastern boundary of the cratonic lithosphere is close, in most places, to the geologically defined Tasman Line and provides a new, deep-lithospheric definition of this line. East of this boundary, the lithosphere transitions to thin, warm lithosphere underlying the volcanically active east of the continent. This transition is sharp in the north, where it is located just west of the Georgetown Inlier, whereas an area of moderately thick, transitional lithosphere is present in the south-central part of the continent.
TEC variation over Europe during the intense tectonic activity in the area of  Arkalochori of Crete on December of 2021
Authors: Contadakis Michael E. , Arabelos Demeter N. , Pikridas Christos , Bitharis Styllianos , Scordilis Emmanuel M.
Published: March 2022

This paper is one of a series of papers dealing with the investigation of  the Lower ionospheric variation on the occasion of an intense tectonic activity.In the present paper, we investigate the TEC variations during the intense seismic activity in Arkalochori of Crete on December 2021 over Europe. The Total Electron Content (TEC) data are been provided by the  Hermes GNSS Network managed by GNSS_QC, AUTH Greece, the HxGN/SmartNet-Greece of Metrica S.A, and the EUREF Network. These data were analysed using Discrete Fourier Analysis in order to investigate the TEC turbulence band content. The results of this investigation indicate that the High-Frequency limit fo of the ionospheric turbulence content, increases as aproaching the occurrence time of the earthquake, pointing to the earthquake epicenter, in accordane to our previous investigations. We conclude that the Lithosphere Atmosphere Ionosphere Coupling, LAIC, mechanism through acoustic or gravity waves could explain this phenomenology.

 

Keywords: Seismicity, Lower Ionosphere, Ionospheric Turbulence, Brownian Walk, Aegean area.
Jupiter's internal structure and dynamics inferred from a high resolution magnetic field and secular variation model
Authors: Sharan Shivangi , Langlais Benoit , Amit Hagay , Pinceloup Mathis , Thébault Erwan , Verhoeven Olivier
Published: March 2022

The interior of Jupiter can be described broadly as a dense core surrounded by fluids, dominantly hydrogen and helium. The hydrogen rich metallic fluid generates the strongest planetary magnetic field in the Solar System. Modelling and interpreting this field give essential information about the dynamo process inside Jupiter. However, the depth of the dynamo region and the temporal variation of the magnetic field are still debatable. Here we use the Juno mission data across four years to derive an internal magnetic field model using spherical harmonic functions. We take the fluxgate magnetometer measurements acquired during the first 28 perijoves to compute a main field model to degree 13, and a secular variation model to degree 8. The power spectrum of the main field model is used to investigate the radius of the dynamo region. We use the properties of the non-zonal and quadrupole family spectra to infer that the convective region has an upper boundary at 0.843 ± 0.015 Jupiter radius. The slope of the secular variation timescales indicate that the dynamo is dominated by advective effects. The secular variation (SV) displays a maximum near the equator with a dipole structure in agreement with zonal drift of the Great Blue Spot. However, numerous small scale SV structures at mid and high latitudes suggest that the flow at the interior is complex involving both zonal and non-zonal features.
Temporal changes of heat-attributable mortality in Prague, Czech Republic, over 1982–2019
Authors: Urban Ales , Fonseca-Rodríguez Osvaldo , Di Napoli Claudia , Plavcová Eva
Published: March 2022

While previous research on historical changes in heat-related mortality observed decreasing trends over the recent decades, future projections suggest increasing impact of heat on mortality in most regions of the world. This study aimed to analyse temporal changes in temperature-mortality relationships in Prague, Czech Republic in the warm season (May-September), using a daily mortality time series from 1982 to 2019. To investigate possible effect of adaptation to increasing temperature, we divided the study period into four decades (1980s–2010s). We used conditional Poisson regression models to identify decade-specific relative risk of heat-related mortality and to calculate the annual number of heat-attributable deaths and the heat-attributable fraction of total warm season deaths. We estimated their trends over the whole study period by a generalized additive model with non-parametric smoothing spline. Our results showed that the unprecedentedly hot 2010s was associated with approximately twice as large relative risk of heat-related mortality than in previous decades. This resulted in the reversal of the trend in heat-attributable mortality in the 1990s and its increase during the last two decades. Our findings highlight the importance of further improvement of adaptation measures such as heat-and-health warning systems to protect the heat-susceptible population.
Multi-objective Inverse Modelling Using Physically based Metrics
Authors: Farokhzad Pouya , Asadzadeh Masoud , Holländer Hartmut
Published: March 2022

The heterogeneity in the soil medium makes it economically impossible to measure the soil characteristics across the whole soil profile. Inverse modelling configures a computer model to simulate the groundwater system and calibrates it to identify the soil characteristics in all grid-cells defined in the model. In classic inverse modelling approaches, residuals between simulated and measured groundwater head time series are converted into a single likelihood function to be maximized; therefore, the information content in the measured data is not fully exploited in those approaches. Moreover, the large number of grid-cells makes inverse modelling an ill-posed optimization problem with more unknown parameters than known measured values, leading to different parameter sets having a similar model performance. Despite recent advances in groundwater calibration practices, such as the regularization approach, there is a considerable room to improve groundwater model calibration using information content in the measured data. Regularization aims to add various sets of information to the calibration to tackle the non-uniqueness problem. However, this approach could associate with a considerable degree of subjectivity and uncertainty. This study seeks a novel approach to extract information content from measured data in the form of physically-based metrics that are often called signatures for improving the identifiability in the groundwater model calibration. Moreover, this study proposes a novel automated powerful inverse modelling strategy using a multi-objective approach to incorporate most of the information content through physically meaningful metrics to obtain more consistent models. The benchmark Freyberg 1988 synthetic case study, in which the true model parameter values are known, is used to demonstrate the applicability and potentials of the proposed framework. The reconstructed Freyberg case study in MODFLOW 2005 showed the framework has the ability to find consistent estimates of the groundwater model parameters.
Analysis of TGE-producing clouds using satellite data
Authors: Svechnikova Ekaterina , Sarafanov Fedor , Ilin Nikolay
Published: March 2022

Thunderstorm ground enhancement (TGE) is energetic radiation generated in electrified clouds and observed on the ground. The enhancement of flux of electrons and gamma-rays is accompanied by a variation of the electric field signifying the movement of an electrified cloud above the measurement point. The operation of the Aragats Research Station (Armenia, 40.47N, 44.18E, 3200 m above sea level) lead to the creation of a vast dataset on TGE parameters including meteorological conditions of its occurrence. The study of the energetic radiation of clouds is important for understanding the processes of interaction of energetic particles, the evolution of convective phenomena, microphysical processes, and charge separation in clouds.

The data on electric field and count rate measured in Aragats characterizing TGE events and data of satellite EUMETSAT–8 reveals correlations characterizing the convective patterns associated with TGEs. The source of the analyzed satellite data is SEVIRI (Spinning Enhanced Visible Infra-Red Imager) - an optical scanner operating in 12 spectral channels. The SEVIRI radiometer, installed on MSG satellites, has 12 channels that provide images of the Earth's surface every 15 minutes. The high-resolution channel in the visible range has a resolution of 1 km (for low latitudes), the other channels - 3 km. The frequency of updating satellite data is 15 minutes, which makes it possible to characterize in detail the dynamics of the development of convective phenomena.

The detected correlation between satellite data and data on particle fluxes for TGE events enables us to describe the probability of TGE occurrence by a new index based on a linear combination of measuring channels. The index characterizes the in-cloud conditions of TGE occurrence and is helpful for automatic analysis of measurement data and further development of TGE-forecasting systems.
Spatio-temporal synchronization of heavy rainfall events triggered by atmospheric rivers in North America
Authors: Wolf Frederik , Vallejo-Bernal Sara M. , Boers Niklas , Marwan Norbert , Traxl Dominik , Kurths Jürgen
Published: March 2022

Atmospheric rivers (ARs) are filaments of extensive water vapor transport in the lower troposphere. They are important triggers of heavy rainfall events, contributing to more than 50% of the rainfall sums in some regions along the western coast of North America. ARs play a crucial role in the distribution of water, but can also cause natural and economical damage by facilitating heavy rainfall. Here, we investigate the large-scale spatio-temporal synchronization patterns of heavy rainfall triggered by ARs over the western coast and the continental regions of North America.

For our work, we employ daily ERA5 rainfall estimates at a spatial resolution of 0.25°x0.25° latitude and longitude which we threshold at the 95th percentile to obtain binary time series indicating the absence or presence of heavy rainfall. Subsequently, we separate periods with ARs and periods without ARs and investigate the differing spatial synchronization pattern of heavy rainfall. To establish that our results are not dependent on the chosen AR catalog, this is conducted in two different ways: first based on a recently published catalog by Gershunov et al. (2017) , and second based on a catalog constructed using the IPART algorithm (Xu et al, 2020). For both approaches, we subsequently utilize event synchronization and a complex network framework to reveal distinct spatial patterns of heavy rainfall events for periods with and without active ARs. Using composites of upper-level meridional wind, we attribute the formation of the rainfall synchronization patterns to well-known atmospheric circulation configurations, whose intensity scales with the strength of the ARs. Furthermore, we demonstrate that enhanced AR activity is going in hand with a suppressed seasonal shift of the characteristic meridional wind pattern. To verify and illustrate how small changes of the high-level meridional wind affect the distribution of heavy rainfall, we, additionally, perform a case study focusing on the boreal winter.

Our results indicate the strong sensitivity of the intensity, location, frequency, and pattern of synchronized heavy rainfall events related to ARs to small changes in the large-scale circulation.
Valley width as a metric to explore lateral erosion in mountain landscapes
Authors: Clubb Fiona , Weir Eliot , Mudd Simon
Published: March 2022

Mountainous landscapes often contain sediment-filled valleys that control ecosystem diversity, flood hazard, and the distribution of human populations. Various mechanisms have been proposed to control the spatial distribution and width of valley floors, including climatic, tectonic and lithologic drivers. Attributing one of these drivers to observed valley floor widths has been hindered by a lack of reproducible, automated valley extraction methods that allow continuous measurements of valley floor width at regional scales. We have developed a new method for measuring valley floor width in mountain landscapes from digital elevation models (DEMs). This method first identifies valley floors based on thresholds of slope and elevation compared to the modern channel and uses these valley floors to extract valley centrelines. It then measures valley floor width orthogonal to the centreline at each pixel along the channel. The result is a continuous measurement of valley floor width at every pixel along the valley, allowing us to constrain how valley floor width changes downstream.

We demonstrate the ability of our method to accurately extract valley floor widths by comparing with independent Quaternary fluvial deposit maps from sites in the UK and the USA. We find that our method extracts similar downstream patterns of valley floor width to the independent datasets in each site. The method works best in confined valley settings and will not work in unconfined valleys where the valley walls are not easily distinguished from the valley floor. We then test current models of lateral erosion by exploring the relationship between valley floor width and drainage area in the Appalachian Plateau, USA, selected because of its tectonic quiescence and relatively homogeneous lithology. We find that an exponent relating width and drainage area (cv= 0.3 ± 0.06) is remarkably similar across the region and across spatial scales, suggesting that valley floor width evolution is driven by a combination of both valley wall undercutting and wall erosion in the Appalachian Plateau. Finally, we suggest that, similar to common metrics used to explore vertical incision across mountain regions, continuous observations of valley width have the potential to act as a network-scale metric of lateral fluvial response to external forcing.
Satellite Remote Sensing Investigations into Changing Ice-shelf Extents in the eastern Weddell Sea Sector of Antarctica
Authors: Homer Nick , Dowdeswell Julien , Christie Frazer
Published: March 2022

Contemporary glaciological research is increasingly focussed on the long-term stability Antarctic Ice Sheet under different climate change scenarios, where changes to atmospheric and oceanic processes are forecast. The floating ice shelves which extend from the ice sheet are of particular research interest because they exert considerable control over the flow of inland ice and respond relatively rapidly to external forcing mechanisms.

In this study, new ice-shelf extent mapping is undertaken by delineating the calving front of the eastern Weddell Sea Sector of the East Antarctic Ice Sheet, where four of Antarctica’s ten largest ice shelves are located. Calving fronts and other lengths of coastline were mapped using an adapted edge-extraction coastline delineation method, entirely within a GIS computing environment, from a suite of remotely-sensed satellite optical (Landsat-series) and synthetic aperture radar (Sentinel-1) imagery. Combined with pre-existing coastline products, a timeseries of ice-shelf areal extent is presented and discussed in the context of known and theorised ice-ocean-atmosphere interactions occurring in the region. In contrast to what is occurring in other regions of the Antarctic Ice Sheet, ice shelves are found to have been synchronously advancing since the 1960s, with only the occasional detachment of large, tabular icebergs causing ice-shelf retreat on sub-decadal timescales. Most recently, total ice-shelf area along the eastern Weddell Sea coastline from Filchner to Fimbul ice shelves, inclusive, has been increasing by c. 550 km2 yr-1 between 2009 and 2019.

Examination of climate reanalysis and sea-ice observations suggests that increasing southward surface wind-speed anomalies along the eastern Weddell Sea coastline are facilitating increased sea-ice concentrations at the margins of the ice shelves and it is argued that this may be increasing the ice-shelves’ structural integrity, limiting iceberg calving activity. Ulimately, however, the ice shelves in this region are still primarily governed by bed-geometry and internal ice dynamical properties. Although this evidence is indicative of a region of the ice sheet in relative mass balance, the future continuation of identified surface air warming trend will increase the likelihood of increased iceberg calving, or indeed ice-shelf retreat or collapse, aping that perviously observed in the Antarctic Peninsula. Further research is, however, needed to assess what effect warming might have on the large-scale atmospheric processes governing changes to the surface winds and related sea-ice concentration anomalies, so that better predictions as to the future evolution of these ice shelves and their inland feeder ice streams may be made.
Geoscience for the next decade: how can geoscientists engage with communities in creating the next industrial revolution?
Authors: Ludden John
Published: March 2022

The International Union of Geological Sciences (IUGS) www.iugs60.org  is the global champion for what is variously referred to as Earth sciences, Solid Earth Science or Geological Sciences. It is part of the International Science Council (ISC) https://council.science/ and works with several related ISC Unions and UNESCO.  Our Earth is faced with mounting challenges related to the climate crisis, which are largely due to the extraction and burning of fossil fuels. The geological sciences have in past decades paved the way in understanding how to locate these fuels for industry to extract and society to use. The geological sciences also underpin mineral extraction, provision of building materials, groundwater, quality of soils and many other issues all of which are essential for human life on Earth.

The transition is underway and geoscientists will lead on several issues, most of which will raise ethical issues: subsurface energy systems in terms of ground stability, seismicity, extent of the resource the safety of the process; mining and the need for critical metals to satisfy new energy technologies – this includes more mining locally and ethically, thus affecting global mining regions and ethically, but also mining in extreme conditions e.g., on the seafloor or the moon; intensive farming and food production and the impacts on water supply and soil quality; the continued need for gold to underpin cryptocurrency; the need for sustainable investment and the move away from oil and gas investments.

There are many more examples and all require a reasoned approach involving a delicate interplay of engineering, business, scientists including social and economic experts, and the public. The geological sciences will continue to be the part of the Earth systems science domains that drive economic growth.  International Unions and meetings such as EGU are fora in which these debates can happen, however all too often they fail to bring together all the stakeholder in the debate.

We as geoscientists need to create the space to engage with the wider communities in the next industrial revolution.

 

 
Historic spatial patterns of compound flood events in UK estuaries
Authors: Lyddon Charlotte , Robins Peter , Lewis Matt , Barkwith Andrew , Haigh Ivan , Vasilopoulos Greg , Coulthard Tom
Published: March 2022

Combination estuarine flooding is driven by extreme sea-levels and river discharge occurring at the same time, or in close succession. We hypothesise the drivers of flooding rarely occur independently and operate and co-operate at sub-daily timescales. There is a need to accurately capture fluvial and sea-level interactions at a sub-daily timescale to understand the relative timing and duration of compound flooding hazards in estuaries to support forecasts and warnings, emergency response and long-term management plans. This research analyses the co-cooccurrence of extreme sea-level and river discharge events using historic river flow data from 126 gauges and tide gauge data from 27 locations across Britain, which were analysed to identify estuaries that are susceptible to compound flooding events. Daily mean and maximum river discharge, and river discharge at 15-minute frequency were analysed to identify extreme peaks in the records, and corresponding skew surge values identified within a time window based on average hydrograph duration. Results show that daily mean river discharge underestimates peaks in the record and does not accurately capture hydrograph behaviour. This research is the first time that 15-minute frequency river discharge data has been used to characterise hydrograph behaviour and identify i) peaks over threshold; ii) top 500 peaks and corresponding skew surges to determine dependence based on Kendall’s rank correlation and the number of occurrences between extreme drivers each storm season (May-June). Different methods of data selection and identification of peak river discharge events generates different results. The duration of river discharge peaks, total water level, lag time, and overlap between peaks is calculated to identify locations where co-occurrences are likely to happen. The results identify a clear east-west split in dependence, with gauges on the west coast of Britain showing stronger correlations. There are more co-occurrences of extreme sea and fluvial levels each storm season in Northwest England and West Scotland. Estuaries that are most susceptible to compound events based on the Kendall’s rank correlation τ, seasonal occurrences, and potential for river discharge and sea-level peaks to overlap based on duration and lag time are identified. The results identify 46 gauges that are highly susceptible to compound flooding, notably the Rivers Lune and Eden, with strongest correlation coefficients and highest number of seasonal occurrences. The results highlight spatial variability to the sensitivity of estuaries to combination flood hazard, and the impact of future changes in flood risk that are unresolved currently in management plans.
On the Evolution of Beach Shoreline According to Equilibrium Profile
Authors: Luque Pau , Marcos Marta , Gómez-Pujol Lluís , Orfila Alejandro
Published: March 2022

Shoreline position is a key parameter of a beach state, used as a descriptor of the system response to changes in external forcings, such as sea-level rise. Changes in shoreline position are the result of hydro- and morphodynamic processes taking place in the nearshore, including feedback mechanisms. Due to this complexity, state-of-the-art methodologies aimed at reproducing the variability of the shoreline are based on several assumptions that simplify the problem. One of the most widespread methods uses a beach equilibrium profile whose shape depends only on the beach morphology (i.e., beach slope, berm) and whose location varies with sea level. Here, we derive a general equation for shoreline evolution using the equilibrium profile, and we use it to evaluate the contribution of sea-level rise to shoreline evolution under wave forcing. We also provide analytical closed-form expressions to this shoreline evolution for a 2/3-power curve equilibrium profile and for three different probability distributions of breaking wave height (corresponding to three different families commonly used to describe wave climate). Our general equation is a step forward in the computation of shoreline evolution assuming a realistic equilibrium profile (described by a range of arbitrary parameters). When used to analyze the effects of sea-level rise, it is not constrained to sea-level rises small compared to the berm height. We also provide a novel and easy way to integrate it.
Estimating Flood Peaks from Event Runoff Depth and Hydrograph Time Scales
Authors: Woods Ross , Zheng Yanchen , Quaglia Roberto , Giani Giulia , Han Dawei , Rico-Ramirez Miguel , Coxon Gemma
Published: March 2022

Flood estimation in ungauged basins is important for flood design, and for improving our understanding of the sensitivity of flood magnitude to changes in climate and land cover. Flood estimates by current methods (e.g. statistical regression, unit hydrograph) have high uncertainty, even in places with dense observing networks (e.g. +/- 50-100% in the UK). Reductions in this uncertainty are being sought by using alternative methods, such as continuous simulation using hydrological models (spatially-distributed or lumped), and event-scale derived distribution approaches. The very significant challenges for reliable application of continuous simulation models in ungauged catchments are well described in the literature.

The research reported here is part of a larger project to estimate the probability distribution of flood peak magnitude in ungauged catchments, using an event-based derived distribution method. The derived distribution approach at the event scale typically combines the following elements: a stochastic rainfall model, an event-scale rainfall-runoff model (usually with “losses” and a “baseflow” component), and a runoff routing model. In principle, every element of this approach may be considered as a (seasonally varying) random variable, though previous research has typically considered only the rainfall as stochastic. The flood peak distribution is obtained by integrating over joint distributions of the model elements.

One of the novel aspects of the proposed approach is that, in place of an explicit routing method, we estimate the flood peak magnitude as the ratio of the event runoff depth (mm) to a characteristic timescale of the hydrograph (hours). The event runoff depth is the product of rainfall depth and event runoff coefficient, which in turn depends on both antecedent conditions and event rainfall. The characteristic timescale of the hydrograph is a second temporal moment (temporal “width” of the hydrograph). Although a comprehensive theory exists for space-time influences on this hydrograph time scale, research to date suggests that it depends, to first order, on time scales associated with rainfall and catchment response.

Here we report on extensive (many events, many catchments) testing in the UK of (i) whether the temporal standard deviation of the flow hydrograph is a good choice for the characteristic time scale of the hydrograph in the context of predicting the flood peak (Viglione et al 2010, Journal of Hydrology) (ii) whether the temporal standard deviation of the hydrograph can be predicted from time scales associated with rainfall and catchment response, as proposed by Woods and Sivapalan (1999, Water Resources Research) and Gaál et al (2012, Water Resources Research).
Modelling space weather impacts on UK railway signalling systems
Authors: Patterson Cameron , Wild Jim
Published: March 2022

Track circuits are widely used signalling systems that use electrical currents to detect the presence or absence of a train in predefined sections of a railway network, as such, they are susceptible to interference from geomagnetically induced currents.

This work aims to determine the impact space weather has on realistic track circuits across geologically different regions of the UK under various storm conditions by using the Spherical Elementary Current System method of geomagnetic field interpolation, a ground conductivity model of the UK, a 1D-layered model to provide estimations of the geoelectric field and track circuit modelling techniques developed by Boteler (2021).

Early results of a modelled section of the West Coast Main Line in North West England will be presented.
Representative and Reliable Modeling for Rock Materials: 2D vs 3D 
Authors: Zengin Enes
Published: March 2022

Determination of strength and deformation parameters of rocks are crucially important for many engineering structures. In recent decades, numerical modelling and analysis have become a critical part of engineering projects due to significant advances in software technologies and computational infrastructure. As with the dilemmas brought by every new development, differences between 2D and 3D modelling approaches need to be considered. In nature, rocks are exposed to stresses from multi-dimensions. In order to create representative and reliable models to assess the behaviour of rock, this natural phenomenon must have been taken into account. On the other hand, in many studies on rock mechanics and modelling, 2D models are used. The reasons behind this choice can be listed as computational load, time, effort, and the results being in the preferred and reliable range. In addition, it is an inevitable fact that the importance of 3D modelling will increase since developing technologies and engineering structures begin to push the limits of the known engineering experience of engineers. In this study, 2D and 3D models were created by using Particle Flow Code (PFC) for a Castlegate sandstone sample to evaluate the response of 2D and 3D models under similar stress conditions. For this purpose, uniaxial compressive strength, triaxial compressive strength, and tensile strength tests were performed on both intact rock and gapped (circular in 2D and spherical in 3D) models to obtain data from different scenarios. Although both models provide similar test results, 3D models offer much more detail, especially in parameters such as crack initiation, propagation, and stress localization. Here, it can be said that the differences in the behaviours arise from the number of the balls in 3D models, which is more than 3 times in 2D, and the number of contacts which is more than 6 times, respectively. However, because of this resolution, the model response to stress conditions is closer to nature. The computational load for the 3D model is much higher than the 2D model because of the resolution. Even though 3D models have some drawbacks compared to 2D models in terms of computational load, time, and effort, it can be said that the data they provide is much more representative and reliable, especially in terms of model behaviour.