bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of chaotic advection generated by oscillatory flow on mixing-induced precipitation
Authors: Gonzalez-Subiabre Guido , Fernàndez-Garcia Daniel , Trabucchi Michela , Carrera Jesús
Published: March 2022

Chaotic advection can be created by engineered sequence of extraction and injection of groundwater in aquifers and by creating an engineered oscillatory flow. It has been used in a wide range of applications, including enhancement of degradation during aquifer remediation, in-situ leaching of metals to enhance mining recovery, and dissipation of energy in geothermal systems. Most of these works are based on numerical simulations and little experimental evidence are reported in the literature. In this work, we analyze how an engineered oscillatory flow can favor mixing-induced precipitation, increasing the total amount and the extension of precipitation zone, with the objective to provide new corrective measures based on permeability reduction. For instance, one can isolate a target aquifer region hydraulically by creating an impervious barrier in the mixing zone. Laboratory experiments were used to study the effect of chaotic advection on mixing-induced precipitation. The experiments were performed in a transparent horizontal two-dimensional tank made of plexiglass filled with glass beads. In the experimental investigation, two different chemical solutions containing CaCl and NaCO3 were injected in separate inlet ports with different concentration. oscillatory flow was created by tuning the inflow rate, we analyze the effect of different injection rates on precipitation. As a result, a calcite precipitate layer with different width was formed between the individual solutions. Color tracer tests were injected before and after the experiment to visualize the impact of precipitation.
Identifying active magnetic reconnection in simulations and in situ observations of plasma turbulence using magnetic flux transport
Authors: Li Tak Chu , Liu Yi-Hsin , Qi Yi , Russell Christopher T.
Published: March 2022

For decades, magnetic reconnection has been suggested to play an important role in the dynamics and energetics of plasma turbulence by spacecraft observations, numerical simulations and theory. Reliable approaches to study reconnection in turbulence are essential to advance this frontier topic of plasma physics. A new method based on magnetic flux transport (MFT) has been recently developed to identify reconnection activity in turbulent plasmas. Applications to gyrokinetic simulations of two- and three-dimensional (2D and 3D) plasma turbulence, and MMS observations of reconnection events in the magnetosphere have demonstrated the capability and accuracy of MFT in identifying active reconnection in turbulence. In 2D, MFT identifies multiple active reconnection X-lines; two of them have developed bi-directional electron and ion outflow jets, observational signatures for reconnection, while one of the X-line does not have bi-directional electron or ion outflow jets, beyond the category of electron-only reconnection recently discovered in the turbulent magnetosheath. In 3D, plentiful reconnection X-lines are identified through MFT, and a new picture of reconnection in turbulence results. In space, MMS observations have provided first evidence for MFT signatures of active reconnection under varying plasma conditions throughout the Earth's magnetosphere. MFT is applicable to in situ measurements by spacecraft missions, including PSP and Solar Orbiter, and laboratory experiments.
Optimising natural flood management benefits from peatland restoration
Authors: Evans Martin , Allott Tim , Brown David , Edokpa Donald , Goudarzi Salim , Holden Joseph , Howson Tim , Johnston Adam , Kay Martin , Milledge David , Rees Joe , Shuttleworth Emma , Spencer Tom
Published: March 2022

Across the world restoration of degraded peatlands involves manipulation of peatland hydrology. Often this includes blocking of drainage and changing of land cover types. These landscape scale interventions in the peatland system have the potential to significantly modify runoff from peatland systems and so to be incorporated into schemes of natural flood management. In this paper we report on results from the 4 year PROTECT project which aims to optimise peatland restoration to support NFM benefits in the degraded peatlands of upland Britain. Field experiments based on a BACI analysis of over 20 peatland microcatchments along with hydrological and hydraulic modelling approaches have underpinned a series of key findings including: reductions in peak discharge and longer lag times for runoff from re-vegetated peatlands particularly associated with sphagnum growth; Reductions in peak discharge associated with optimised peat dams which allow partial drawdown between storm events; continued delivery of NFM benefit from restoration at timescales in excess of 10 years; and identification of a key role for dam permeability in optimising NFM benefits from drainage line blocking.

Taken together these data support the potential role of peatland restoration in NFM schemes and suggest that with careful optimisation synergies between the needs of peatland restoration and flood protection in headwater communities can be realised.
Rheology of plagioclase transforming under high pressure and temperature conditions: insights from deformation experiments
Authors: Baisset Marie , Gasc Julien , Deldicque Damien , Moarefvand Arefeh , Schubnel Alexandre , Labrousse Loïc
Published: March 2022

In convergent zones, plagioclase, the main rock forming mineral of the lower continental crust, breakdowns with increasing pressure via two reactions, respectively involving its calcic (anorthite) and sodic (albite) end-members. In the presence of water, anorthite starts to breakdown at 1.5 GPa and 700°C into an assemblage of zoisite, kyanite and quartz, while  albite breakdowns into jadeite and quartz at higher pressure (~ 2 GPa). These two reactions involve large volume reduction (~15%), as well as the nucleation and growth of new minerals with mechanical properties different from the initial plagioclase, both of which may have important mechanical consequence if the rock transforms while deforming.

The aim of our study is to understand and further quantify the impact of these transformations on the rheology of the continental lower crust. Deformation experiments were performed on plagioclase aggregates in a 3rd generation Griggs-type apparatus (Moarefvand et al. 2021), equipped with an acoustic emission monitoring system. Focussing on the lower pressure reaction (an + H2O = zo+ky+qz), expected to be of paramount importance at laboratory timescales because of the fast nucleation of Ca-Al silicates, samples were deformed at various P-T conditions (1 GPa to 2 GPa  and 700°C to 800°C) and two different strain rates (4e-5 /s an d 4e-6 /s). In addition, various initial water content were tested in order to study the mechanical behavior of the aggregate under different reaction kinetics.

Our results suggest that under these experimental conditions, the rheology of plagioclase is controlled by the complex feedbacks between hydration, reaction kinetics and strain rate. Under ‘wet’ conditions, the reaction is fast and the rheology observed is consistent with that of ‘wet’ plagioclase. Additional softening is observed when the reaction takes place, during which plagioclase behaves as a weak assemblage of albite and zoisite (+-mica). Under dry conditions, the reaction is much slower and an inverse ductile to brittle transition was observed, i.e. embrittlement was observed at the slowest strain rate only, conditions under which stress may build up (‘dry’ rheology) while the reaction is fast enough to trigger embrittlement of the sample.

These results further our understanding of the lower crust rheology and in particular, of the conditions under which intermediate-depth seismicity linked to eclogitization of the lower continental crust may be observed in convergent zones.
Provision of wind information for site tenders for offshore wind farms according to WindSeeG in the German North and Baltic Seas
Authors: Möller Thomas , Spangehl Thomas , Brast Maren , Andersson Axel , Tinz Birger
Published: March 2022

The construction of offshore wind farms in Germany's Exclusive Economic Zone (EEZ) is an important component for the successful implementation of the energy transition. In 2021 the Federal Network Agency started to launch yearly tenders for sites in the North Sea and Baltic Sea which are conducted in cooperation with the Federal Maritime and Hydrographic Agency (BSH) according to the Wind Energy Act (WindSeeG). The German Meteorological Service (DWD) supports the BSH in compiling the required wind information. This information is made publicly available by the BSH to bidders via the PINTA portal (https://pinta.bsh.de) as part of the tendering procedures.

Detailed information on the wind conditions on the sites is crucial for the bidders' bid calculations. This information is compiled in collaboration by the BSH and the DWD with the participation of external contractors. In detail, these are in-situ measurements on the research platforms in the North Sea and Baltic Sea, FINO1, FINO2 and FINO3 (https://www.fino-offshore.de/de/index.html). Furthermore, this comprises one-year LiDAR measurements are carried out by external contractors on behalf of the BSH at the sites to be tendered, as well as data and evaluation results of the COSMO-REA6 and ERA5 reanalyses are provided by the DWD. These data sets are the basis for the preparation of summarised overall reports on the wind conditions on the sites.

The reanalysis and measurement data provided allow a detailed investigation of the seasonal variability as well as an in-depth assessment of the current as well as the historical wind field on each site. The focus of the measurements is on the heights relevant for future wind turbine types, i.e. in the range of 40 to 200 metres. The evaluation of the reanalyses is carried out for the grid points closest to the areas as well as the surrounding grid points and is validated using the existing measurement data. Previous evaluations show a very good correlation, which gives the reanalyses a high significance to determine the wind conditions on the sites. In addition, information on interannual variability is required. Long-term time series of geostrophic wind derived from air pressure data from coastal stations enable an assessment of multi-decadal variations.
Karst development in different tectonic settings (Middle East, Greece, South China), concept analysis and first findings towards hydrology modeling reconsideration
Authors: Moraetis Daniel , Palvopoulos Kosmas , Fassoulas Charalambos , Scharf Andreas , Mattern Frank , Yu Xuan , Pennos Christos , Adamopoulos Kostas , Zacharias Stylianos , Hamdan Hamdan , Nikolaidis Nikolaos
Published: March 2022

As part of the International Geoscience IGCP-715 project, we present the core objective and preliminary analyses on the karst development of the study areas. Our aim is to further characterize the geomorphologic features of the extended karst of Koiliaris Critical Zone Observatory (KCZO), Crete, Greece. Simultaneously to better understand the main drivers of karst development we compare the CKZO karst system with other areas in different tectonic contexts such as Oman (Salma Plateau), the northern UAE and southern China (Guilin karst area).

Hydrological studies and previous geomorphologic analysis of KCZO suggest that 27% of the total water budget is coming from the adjacent watershed in the east where an extensive karst system with two explored super-deep caves is situated (Liontari Cave - 1100 m, Gourgouthakas Cave - 1200 m). The area is build up by a continuous carbonate succession exceeding 5 km in depth, lying on top of the Hellenic subduction zone. Field work and Google Earth mapping show two dominantly striking directions of failures (fault, fracture surfaces), trending E-W to ESE-WNW (90-120°) and N-S to NNE-SSE (0-22.5°). The N-S surfaces are mainly fractures while the E-W ones are mainly thrusts and/or strike-slip faults with obvious large displacements of hundreds of meters. The karst development in a subduction zone with dramatic thrusting on the overriding plate has created super-deep caves which are controlled by the vertical bedding and a series of faults and fractures. The area exhibits two layers with different hydraulic properties, a fast water-transferring zone and a slower one which is consistent and supports the hypothesis of the hydrologic model.  

At the Salma Plateau, in Oman, the karstic system is related to rapid uplifted Eocene limestones that overlay the Semail Ophiolite. There is a large cave (Majilis Al Jinn) at an area of interconnected fractures (and/or faults?). It is the only karstic system presented inhere which has similarities with the karstic system in the KCZO.

At the UAE and northern Oman (Musandam) is an active collision zone between Arabia and Eurasia with 2000-m-thick allochthonous Mesozoic limestones. The area lacks a subsurface karst system, and the only karst has developed in steep wadis.

Finally, the Guilin area in China represents a former passive margin with a Devonian limestone. It features a spectacular karst of conical peaks (fengcong) and tower peaks (fenglin). Caves exhibit mainly a horizontal development and there is no similarities to the KCZO.
Aerosol Thermodynamics using Machine Learning
Authors: Tost Holger , Spichtinger Peter ,   BINARY Team
Published: March 2022

Aerosol chemical composition is an important driver for hygroscopic growth and hence cloud activation. A major fraction of the aerosol consists of inorganic components, for which thermodynamic equilibrium models are commonly used to describe the chemical composition, including total water uptake.
However, these thermodynamics are relatively computationally expensive calculations, minimising the Gibbs free energy of the total system. Consequently, faster computations are desirable, which can be facilitated using machine learning techniques.

In this study, we apply neuronal networks, being trained on the output of an equilibrium thermodynamics model (ISORROPIA 2), to represent both the chemical composition and associated aerosol water uptake. We investigate the quality of the trained network against independent data from the equilibrium model and find a good agreement of the trained network model against the original data. Furthermore, we also test the applicability of the trained model in a parameter space outside of the trained data set to analyse whether the trained network is able to properly represent the physico-chemical system, and hence a suitable replacement of the equilibrium model by a neuronal network is appropriate.
Effects of CME removal and observation age on solar wind data assimilation
Authors: Turner Harriet , Owens Mathew , Lang Matthew
Published: March 2022

Accurate space weather forecasting requires knowledge of the solar wind conditions in near-Earth space. Data assimilation (DA) combines model output and observations to find an optimum estimation of reality and has led to large advances in terrestrial weather forecasting. It is now being applied to space weather forecasting. Here, we use solar wind DA to reconstruct the conditions from 30 solar radii to Earth's orbital radius and over all longitudes and produce solar wind speed forecasts. In this study, we assimilate observations from the Solar Terrestrial Relations Observatory (STEREO) and the Advanced Composition Explorer (ACE). Analysis of two periods of time, one in solar minimum and one in solar maximum, reveals that assimilating observations from multiple spacecraft is preferable over observations from a single spacecraft. The age of the observations also has an impact on forecast error, whereby the mean absolute error (MAE) increases by up to 23% when the forecast lead time exceeds the time associated with the longitudinal separation between the observing spacecraft and the forecast location. It was also found that removing CMEs from the DA input observations acts to reduce the forecast MAE by up to 10% through removal of false streams in the forecast time series. This work adds further evidence to the usefulness of the L5 space weather monitoring mission, but also shows that a mission to L4 would aid in future solar wind DA forecasting capabilities. 
The ILRS Analysis Centers’ Report on the Evaluation of ITRF2020P
Authors: Pavlis Erricos C. , Luceri Vincenza , Basoni Antonio , Sarrocco David , Kuzmicz-Cieslak Magdalena , Evans Keith , Bianco Giuseppe
Published: March 2022

The member ACs of the ILRS Analysis Standing Committee—ASC, evaluated the preliminary release of ITRF2020—ITRF2020P.  For the most part, this evaluation is based on the reanalysis of part or all of the SLR data from geodetic spherical targets in the model; in particular, we focused on the two LAGEOS and two Etalons from 1993 to the end of 2020, extended by one year of data NOT included in the model: all of 2021. The evaluation report was submitted to ITRS for consideration in the finalization of the ITRF2020 model. Some ACs used additional data that do not contribute to ITRF development for testing. The reanalysis used the same improved modeling that was used for the development of the ILRS contribution to ITRF2020.

We will focus on the implementation of the new approach in handling systematic errors at the stations and how users will need to adapt their data analysis procedures to benefit the most from the new model. The 2021 ILRS contribution to ITRF2020 minimized the scale difference between SLR and VLBI below 2 mm (ITRF2014 ~9 mm). The reanalysis incorporates an improved “target signature” model (CoG) for better separation of true systematic errors from errors in describing the target’s signature. This model will be periodically updated from now on, so that it represents accurately the state of operations at all sites in the ILRS network of tracking stations. SLR data users should make sure from now on to use each ITRF model with the appropriate (consistent) Data Handling file and “target signature” model.

The presentation will provide an overview of the analysis procedures and models, and it will demonstrate the level of improvement with respect to the previous ILRS product series, focusing especially on the Core ILRS sites.
Global analysis of emergency service provision to vulnerable populations during floods of various magnitude under climate change
Authors: Johnson Sarah , Wilby Robert , Yu Dapeng , Matthews Tom
Published: March 2022

In a world of increasing global flood hazards, vulnerable populations (very young and elderly) are disproportionately affected by flooding due to their low self-reliance, weak political voice and insufficient inclusion into climate adaptation and emergency response plans. These individuals account for most flood casualties and often rely on emergency services due to flood induced injuries, exacerbated medical conditions, and requiring evacuative assistance. However, emergency service demand often exceeds the potential capacity whilst flooded roads and short emergency response timeframes decrease accessibility, service area, and population coverage; but how does this compare across the globe and what will the future hold?

To answer this question, a global analytical framework has been created to determine the spatial, temporal, and demographic variability of emergency service provision during floods. This is based on global fluvial and coastal flooding (at 10-year and 100-year return periods), and present and future flood conditions (present-day and 2050, under RCP 4.5 and RCP 8.5 climate scenarios). The framework includes a hotspot analysis to identify the extent and distribution of flood hazards and at-risk vulnerable populations, an accessibility analysis to identify emergency service accessibility to vulnerable populations based on restrictions of flood barriers and response-time frameworks, and a vulnerability analysis to compare the environmental injustice of emergency service provision between key demographic groups.

The highlighted geographical and temporal differences in emergency service provision globally and between regions, in addition to the framework itself, can be used by national and international organisations to inform strategic planning of emergency response operations and major investments of infrastructure, services, and facilities to maximise the benefit to the disproportionately affected vulnerable populations. This includes the production of more detailed flood hazard and evacuation maps that highlight vulnerability hotspots, the prioritisation of vulnerable population groups in emergency response plans to minimise geographic and population disparities of flood injuries and fatalities, and the allocation of emergency service hubs in regions of high vulnerability but low emergency response provision.
Uncertainty in observed coastal vertical ground motions matters for local sea-level projections
Authors: Le Cozannet Gonéri , Thiéblemont Rémi , Rohmer Jeremy , Wöppelman Guy , Slangen Aimée B A , Hermans Tim H J
Published: March 2022

While the understanding and modelling of RSLC due to ocean density and mass changes have greatly improved over the past few decades, RSLC contributions due to vertical ground motions (VGMs) remain a major source of uncertainty, in particular for local scales. Here, VGMs relate to ground motions that have imprints of a few kilometres, as opposed to broad scale land motion such as Glacial Isostatic Adjustment (GIA). VGMs can be caused by processes such as groundwater extraction or the load of infrastructure on recent sediment deposits, all of which vary in space and time, and are difficult to project in the future.

A common technique to account for the VGM contribution in RSLC projections is to use GNSS stations to identify present days rates, identify causes and extrapolate rates where appropriate. However, previous works that followed this approach generally considered a unique GNSS solution (e.g., only NGL) together with a unique trend estimate algorithm, while often several GNSS solution based on different trend estimate techniques are available (i.e., ULR, NGL, JPL and GFZ). Ignoring these alternative estimates and their potential discrepancies may therefore ignore further sources of uncertainty.

Here, we analyse how VGMs derived from 4 GNSS records (ULR, NGL, JPL and GFZ) and trend estimates affect uncertainty in future RSLC at tide gauges. Residual local VGM trend distributions are obtained from a Monte Carlo procedure by removing the effect of GIA and solid earth deformation induced by contemporary mass redistribution. This procedure is repeated using three different trend estimate techniques, all based on the MIDAS robust trend estimator, where GNSS timeseries offsets are (i) automatically detected, (ii) initially declared or (iii) manually corrected. We find that the choices of GNSS solution or the trend estimate technique can both substantially affect estimates of the VGMs leading to differences of about 1mm/year, which is approximately one third of sea-level rise rates observed today. Accounting for the uncertainty and discrepancy in GNSS records can change AR6 RSLC median projections by more than -/+ 15% in 2100. This is larger than the differences between SROCC and AR6. Likely ranges and skewness of projected RSLC distributions are also affected. We suggest that sea-level scenarios, whether median, likely, probabilistic or high-end, can benefit substantially from advances in observing and projecting local vertical ground motions.
Wave activity in and below Venusian clouds with the IPSL Venus GCM
Authors: Lebonnois Sebastien , Martinez Antoine , Millour Ehouarn
Published: March 2022

Recent analyses mostly based on Akatsuki datasets brought many observational informations about the planetary-scale waves (Imai et al., 2019; Kajiwara et al., 2021) and thermal tides (Scarica et al., 2019, Akiba et al., 2021) at the top of the Venusian cloud layer. Further analysis of these data has enabled to build a view of the angular momentum balance at the cloud top, as a component of our understanding of superrotation (Horinouchi et al., 2020).

To help interpret and understand these wave activities and their impact on the angular momentum budget both in and below the cloud layer, the Venus Global Climate Model (GCM) we are developing at Institut Pierre-Simon Laplace (IPSL) is used in its latest configuration. Similarly to what was done with earlier configurations (Lebonnois et al., 2016), waves are extracted from the simulations to analyze (i) the thermal tide components, (ii) the dominant planetary-scale waves present in the cloud layer, Kelvin- and Rossby-type waves with periods close to 4-6 Earth days, and (iii) wave activity occurring in the deep atmosphere, below the cloud, corresponding to large-scale inertio-gravity waves. These different waves will be compared to observations to assess how the IPSL Venus GCM reproduces observational constraints. Angular momentum budget as evaluated in the GCM simulations will be discussed, with emphasis on the cloud top region.

References:

Akiba M. et al. (2021), JGR Planets 126, doi:10.1029/2020JE006808

Horinouchi T. et al. (2020), Science 368, 405–409, doi:10.1126/science.aaz4439

Imai M. et al. (2019), JGR Planets 124, doi:10.1029/2019JE006065

Kajiwara N. et al. (2021), JGR Planets 126, doi:10.1029/2021JE007047

Lebonnois S et al. (2016), Icarus 278, 38-51, doi:10.1016/j.icarus.2016.06.004

Scarica P. et al. (2019), Atmosphere 10, 584, doi:10.3390/atmos10100584

 
Neural Partial Differential Equations for Atmospheric Dynamics
Authors: Gelbrecht Maximilian , Boers Niklas
Published: March 2022

When predicting complex systems such as parts of the Earth system, one typically relies on differential equations which can often be incomplete, missing unknown influences or higher order effects. Using the universal differential equations framework, we can augment the equations with artificial neural networks that can compensate these deficiencies. We show that this can be used to predict the dynamics of high-dimensional spatiotemporally chaotic partial differential equations, such as the ones describing atmospheric dynamics. In a first step towards a hybrid atmospheric model, we investigate the Marshall Molteni Quasigeostrophic Model in the form of a Neural Partial Differential Equation. We use it in synthetic examples where parts of the governing equations are replaced with artificial neural networks (ANNs) and demonstrate how the ANNs can recover those terms.
Electromagnetic monitoring of the Cumbre Vieja eruption (La Palma, Canary Islands)
Authors: Martínez van Dorth David , Piña-Varas Perla , Cabrera-Pérez Iván , Ledo Juanjo , D'Auria Luca , Pérez Nemesio
Published: March 2022

Geophysical monitoring is essential to understand the activity and behaviour of volcanoes, especially when new or unusual signs are detected. Monitoring would help to address critical issues, such as the evolution of the magma at depth, which is of particular interest when the volcanic event takes place in populated areas.  Among the geophysical methods, the electromagnetic ones have not been widely used in volcanic monitoring. However, these methods are very sensitive to the presence of fluids and therefore, to the presence of magma, since this will have a significant impact on the electrical resistivity of the subsoil.

Thus, after the onset of the volcanic eruption that began on September, 19, 2021 in the Cumbre Vieja area, on the island of La Palma (Canary Islands), several magnetotelluric stations were installed to perform a volcanic monitoring experiment. The different geophysical stations were installed in the surroundings of the volcanic edifice, as well as in those areas where the epicenters of the major seismic swarms were located. Magnetotelluric stations have been installed for continuous monitoring, recording electric and magnetic fields in the N-S and E-W directions. According to the quality of the data, we have obtained transfer functions for the period range of 0.001 - 100 s.

The aim of this experiment is to analyze the possible variations of the apparent resistivity and phase curves in time. In addition, the electrical resistivity model of the island published in 2020 will be compared with the seismicity that has been occurring since the beginning of the volcanic crisis.

The first preliminary results show slight changes in time and, in comparison with the previous data, this could be related to magmatic movements at depth. Furthermore, the comparison of the seismicity with the previous electrical resistivity model shows that most of the epicenters are located outside the clay cap. This epicenter-resistivity structure relationship is highlighting the considerable difference in the behavior of the clay layer and the surrounding rocks, which is somewhat validating the resistivity model and its interpretation.
Present strain partitioning in SE Spain. Insights from CGNSS data
Authors: Martin-Rojas Ivan , Sánchez-Alzola Alberto , Medina-Cascales Ivan , Borque María Jesús , Alfaro Pedro , Gil Antonio
Published: March 2022

SE Iberia Tectonics is presently dominated by the NNW-SSE convergence between the Eurasian and Nubian plates. Farther east, the eastern Spanish coast and the Valencia Trough are dominated by ENE-WSW extension related to thermal subsidence. This extension has been interpreted as the final stage of abort rift responsible for the ENE motion of the Balearic promontory. Our data from 11 CGNSS stations permit us to discuss the deformation partitioning in SE Iberia related to the two abovementioned processes.

We identify three kinematic domains: a relatively stable domain, a domain moving towards NNW and undergoing NNW-SSE shortening, and a third domain relatively moving towards ENE and experiencing ENE-WSW extension. Our results indicate that plate convergence-related NNW-SSE shortening is mainly absorbed by the Eastern Betic Shear Zone (EBSZ), in agreement with previous studies, but also show that a significant fraction of this shortening is accommodated south of the EBSZ.

We also identify and quantify for the first time ENE-WSW extension northeast of the EBSZ. We propose that this extension could be absorbed by basement normal faults whose surface expression is obscured due to decoupling of deformation between the basement and the cover. Our results shed light on the tectonic puzzle of SE Spain.
Digitizing archive atmospheric electric potential gradient data for scientific research
Authors: Magos Levente , Bozóki Tamás , Bozsó István , Bór József , Horváth András , Kuslits Lukács , Timkó Máté , Buzás Attila
Published: March 2022

Nowadays, there is a great need for the preservation of historical data in earth sciences as time series covering a long time period are of extreme importance in studying long-term variations of the Earth’s environment. This is the case in the field of atmospheric electricity research, too. In this work, we focus on one of the most frequently recorded parameters of the discipline, the atmospheric electric potential gradient (PG).

The PG is the reverse of the vertical atmospheric electric field, a quasi-DC quantity measured in Vm-1 units usually near the ground most often at 1–3 m heights [1]. The PG has been measured quasi-continuously at the Széchenyi István Geophysical Observatory near Nagycenk, Hungary (NCK, 47°38’ N, 16°43’ E) since 1962 [2]. Between 1962 and 2011, the PG was recorded on photo papers which were evaluated manually and the hourly averaged PG values were archived. Nevertheless, the original photopapers, too, were kept.

In this contribution, we present a recently developed image processing algorithm to digitize the analogue PG records on the old photo papers semi-automatically. By means of this algorithm, PG averages can be obtained with a temporal resolution as high as 30 s. In order to validate the digitized data, they have been compared to the archived hourly PG averages between 1999 and 2009. The long-term, seasonal, and diurnal variations of the PG at NCK between 1999 and 2009 based on the digitized and the archived data are also presented.

[1] Rycroft, M. J., Israelsson, S., and Price, C.: The global atmospheric electric circuit, solar activity and climate change, J. Atmos. Sol.-Terr. Phy., 62, 1563–1576, 2000.

[2] Bór, J., Sátori, G., Barta, V., Szabóné-André, K., Szendrői, J., Wesztergom, V., Bozóki, T., Buzás, A., and Koronczay, D.: Measurements of atmospheric electricity in the Széchenyi István Geophysical Observatory, Hungary, Hist. Geo Space. Sci., 11, 53–70, https://doi.org/10.5194/hgss-11-53-2020, 2020.
Comparative study of undissolved and karstified limestone based on microtomography 
Authors: Białecki Mariusz , Sharma Rishabh Prakash , Cooper Max P , Szymczak Piotr
Published: March 2022

We develop methods for qualitative and quantitative assessment of the transformation of pore geometry of a rock as a result of karstification. We then apply these tools to characterize dissolution-induced changes in Miocene limestone samples collected from a quarry located near Smerdyna (Poland), where intense epikarst development is observed, with the formation of hundreds of solution pipes. Partially dissolved samples collected in the immediate vicinity of the pipes are compared with undissolved samples collected several meters away.

For both types of samples 26 micron resolution grayscale X-ray scans has been performed, and cubical regions of interest of size 506^3 voxels, which corresponds to (13,156 mm)^3, have been studied. Images have been segmented by tuning the grayscale threshold to match the experimentally measured porosity values of respective samples. Additionally, based on the segmented tomograph of undissolved sample another geometry was numerically created in order to mimic a uniform dissolution of the rock up to a porosity value equal to that of the dissolved sample.

The irregular geometry of the pore space, vast majority of which forms a single connected component, can be conveniently characterized by a local thickness function,  which corresponds to a diameter of the largest sphere that fits within the pore space and contains a given point. A similar measure can be introduced for the solid component (grains). We have compared thickness distributions  of undissolved and dissolved sample as well as numerically generated uniformly dissolved sample. Such a comparison allowed us to quantify the extent of homogeneity of the natural karstification process.

To further characterize pore geometry, we have calculated the ellipsoid factor, which – based on the axis lengths of the fitted ellipsoids – can be used to characterize how prolate or oblate the pore space locally is. Next, we have used (modified) Flinn diagram to quantify differences between undissolved, numerically eroded and naturally dissolved samples, especially those indicating pore merging and inhomogeneous dissolution.

The above analysis is complemented by calculation of connectivity density – a topological measure of the degree to which a structure is multiply connected. Values obtained for undissolved, numerically dissolved and naturally dissolved samples indicate on ‘excessive’ reduction of interconnections during natural dissolution, which may be understood on the basis of high degree of pore merging due to inhomogeneous dissolution.

Both methods: (generalized) thickness analysis and connectivity calculation emphasise the role of merging of pores and inhomogeneous dissolution in the process of natural dissolution for the analyzed  samples.
Evaluation of the assumptions used in the assessment of future wind resources - A case for CMIP6 in Northern Europe
Authors: Hahmann Andrea N. , Peña Alfredo , García-Santiago Oscar , Pryor Sara C.
Published: March 2022

In 2020, the North Sea already had 19.8 GW or 79% of the European offshore wind installations. The size and number of wind farms in this region are expected to increase substantially to reach climate mitigation targets, with forecasts of offshore wind commitments across Europe adding up to 111 GW of offshore wind by 2030. However, governments base their climate mitigation plans on past historical wind resources data. Still, there is a probable threat that these will change in the future due to climate change during the lifetime of a wind farm. 

The study of future changes in wind resources is not a new subject. A systematic literature search with the keywords "Wind Resources" and "Climate Change" returned over 80 peer-reviewed articles that assessed future wind resources at the global, regional and local scale. Most of these studies used the 10-m wind speed output from the climate or regional model to directly estimate a wind turbine's power production, using the power law and sometimes an idealised power curve. As far as we know, only two studies explored the possible implications of changes in wind direction. 

In this presentation, we explore the implications of the various assumptions. We use the example of the North Sea and Northern Europe and the CMIP6 climate model archive to demonstrate that some assumptions can exaggerate future wind resource changes. We also consider the consequences of the changes in boundary layer stability, wind direction and vegetation changes to the future wind resources in Northern Europe. 
Investigation of shipborne GNSS ZTD retrieval processing parameters by simulation
Authors: Panetier Aurélie , Bosser Pierre , Khenchaf Ali
Published: March 2022

The aim of this work is to study the impact of the processing parameterization on the estimation of the zenith total delay (ZTD) from a shipborne GNSS antenna measurement.

For this purpose, we used a simplified observation model, and simulated a realistic configuration of measurements (ephemerids, troposphere, motion of the shipborne antenna). Different sources of error that could affect the measurement were also simulated. The impact of these errors was then evaluated on the estimation by Kalman filtering, using different parameterizations (multi-constellation, solution sampling, random walk process noise for the ZTD estimates, observation weighting, cut-off angle).

As it could have been expected, low cut-off angle (in the range of 3 to 7 degrees) and multi-constellation provide more accurate results. The choice of the data weighting is shown to significantly impact the difference on the estimates, and the use of a square-root of sine function, or uniform weighting of elevation gives the most conclusive results. High value of random walk process noise for ZTD estimates should also be avoided. Globally, the accuracy of the ZTD estimation can be improved up to more than 90% according to the configuration.

The results of this work will be helpful to set up an optimal parameterization for the processing of massive dataset of GNSS measurements acquired from shipborne antennas.
Celebrating Eric Wood's advances in large domain hydrologic modeling
Authors: Clark Martyn
Published: March 2022

Eric F. Wood was a pioneer in large-domain hydrologic modeling. Building on his work on hydrologic scaling in the 1980s, in the 1990s and 2000s Eric led the community in process-based approaches to hydrologic modeling across large geographical domains. Together with Dennis Lettenmaier, Eric developed the open-source Variable Infiltration Capacity (VIC), which became a leading large-domain hydrologic model used by dozens of research groups around the world. The capabilities of VIC advanced by Eric and Dennis' students and postdocs included improved representation of hydrologic scaling relationships, advanced representation of cold region hydrologic processes, new capabilities for large-domain streamflow forecasting, and understanding the sensitivity of large river basins to climate variability and change. Eric's work in leading community model inter-comparison projects (PILPS) and community large-domain modeling studies (GEWEX/GCIP and GEWEX/GAPP) advanced understanding of the limitations of large-domain hydrologic models and helped identify effective strategies for model improvement. It is clear that most large-domain hydrologic models that are in use today are heavily influenced by the legacy of VIC. As the community continues to advance in developing interdisciplinary approaches to Earth System modeling (integrating advances from terrestrial and aquatic ecology and the social sciences), explicitly representing a broader range of natural and human processes, it is increasingly clear that the community is indebted to the contributions of Eric F. Wood.
Imaging water transport across the soil-snow interface using neutron transmission radiography
Authors: Lombardo Michael , Lehmann Peter , Kaestner Anders , Fees Amelie , van Herwijnen Alec , Schweizer Jürg
Published: March 2022

The soil-snow interface plays a critical role in the release of glide-snow avalanches, which threaten life and infrastructure such as houses, roads, and chair lift masts in alpine areas. One of the important factors controlling glide-snow avalanche release is the presence of interfacial water between the ground and snowpack. Several mechanisms, such as percolation of water from the snow surface and geothermal melting of basal snow layers, have been postulated to explain the formation of this interfacial water. These mechanisms remain, however, poorly understood to poor predictability of glide-snow avalanche release. Here, we demonstrate the use of neutron transmission radiography for investigating the transport of water across the soil-snow interface at laboratory scales. We show that neutron transmission radiography is capable of capturing changes in water content during snow melt processes in both the snow and soil phases. Neutron imaging also revealed that the hydraulic properties of the porous interface between the soil and snow (mimicking a vegetation layer) affect the formation of an interfacial water layer. Improved understanding of the water transport across the soil-snow interface should lead to better prediction of glide-snow avalanche releases in the future.
Remediation of subsoil compaction by subsoiling and deep rooting crops
Authors: Vanderhasselt Adriaan , Steinwidder Laura , D'Hose Tommy , Cornelis Wim
Published: March 2022

Soil compaction forms a major threat to the well-functioning of agricultural soils. By reducing the pore volume and continuity both crop growth and ecological services, like water infiltration and storage, can be negatively impacted. It is often most severe at the interface between topsoil and subsoil, just out of reach of regular tillage operations. At this depth a plough pan can be formed, restricting interaction between top- and subsoil for roots, and gas and water transport. In this study we looked at a combination of mechanical and biological remediation to alleviate this problem. The experiment was performed on a sandy loam field near Ghent, Belgium with a highly compacted plough pan, which almost completely restricted roots to reach the subsoil and was practically impermeable for gases. Subsoiling was performed once in three different maize-based cropping systems: forage maize in monoculture, a ley-arable crop rotation with two years of alfalfa and a maize-winter cereal rotation.

The mechanical remediation (subsoiling) clearly helped to break open the restricting plough pan. Rootablility and air permeability clearly increased, leading to a significant increase in maize yield. On a longer time scale, however, we observed that this loosened soil was very prone to recompaction. In the second year after the subsoiling the highly compacted plough pan returned. This same year also showed no difference between the subsoiled and untreated control in maize yield.

To see if deep rooting crops can help stabilize the loosened soil after subsoiling, this study included treatments with fodder radish and alfalfa as (cover) crops. These crops showed a high rooting density in the subsoil, especially where the tines of the subsoiler had passed. Although this did not seem to improve the overall physical soil quality, it did protect the soil from complete recompaction. The penetration resistance did not markedly increase after standard agricultural practice.
Assessing landslide hazard in the High City of Antananarivo (Madagascar)
Authors: Frodella William , Rosi Ascanio , Spizzichino Daniele , Nocentini Massimiliano , Lombardi Luca , Vannocci Pietro , Margottini Claudio , Tofani Veronica , Casagli Nicola
Published: March 2022

The High City of Antananarivo is one of the most important built cultural heritage sites of Madagascar, and therefore is part of the UNESCO Tentative List. Built on the hilltop of a granite ridge elevating above the Ikopa river valley, it’s renowned for its baroque-style palaces the Rova royal complex and gothic cathedrals dating back to the XIX century. During the winter of 2015, the twin cyclones Bansi and Chedza hit the urban area of Antananarivo, triggering floods and several shallow landslides, which caused thousands of evacuees and many casualties. Between 2018 and 2019 several rockfalls occurred from the rock cliffs of the Analamanga hills destroying housings and killing over 30 people. Both events showed that landslides can pose a high risk to the safety of the inhabitants, the infrastructures, and the cultural heritage of the High City of Antananarivo. To assess landslide hazard an integrated approach was adopted by means of the following actions: i) creation of a multitemporal slope-scale landslide inventory; ii) geotechnical characterization of the involved materials; iii) analysis of shallow landslide susceptibility; iv) runout analysis of debris flows channeling within large creek gullies; v) landslide kinematic analysis of the rockmass; vi) simulation of rockfall trajectories; vii) analysis of rainfall data. The results show that the main factors affecting landslides are slope, lithology, creek-gully erosion and anthropization, while most of the landslide events are clearly triggered by heavy rainfall events. The landslide-prone areas (including shallow landslides, rock falls and debris flows) are located primarily along the cliff bounding the western hill slope, the southeastern sector, where abandoned quarries form large slope cuts, and subordinately in the steep creek catchment just east of the Rova. The produced thematic maps represent fundamental land use management tools to be used as a first step towards a geo-hydrological risk reduction strategy by the institutions and actors involved in the High City protection and conservation. The conducted study represents an important contribution for improving the knowledge on landslides processes in an area with limited data such as Madagascar and Antananarivo in particular, and may be reproduced in cultural heritage sites characterized by similar geomorphological and urban scenarios.