bluuebunny/crossref_metadata_2025 huggingface dataset:
Shear-Wave Splitting in the Alpine Region
Authors: Bokelmann Götz , Hein Gerrit , Kolinsky Petr , Bianchi Irene , Working Group AlpArray
Published: March 2021

To constrain seismic anisotropy under and around the Alps in Europe, we study SKS shear-wave splitting from the region densely covered by the AlpArray seismic network. We apply a technique based on measuring the splitting intensity, constraining well both the fast orientation and the splitting delay. 4 years of teleseismic earthquake data were processed automatically (without human intervention), from 724 temporary and permanent broadband stations of the AlpArray deployment including ocean-bottom seismometers. We have obtained an objective image of anisotropic structure in and around the Alpine region, at a spatial resolution that is unprecedented. As in earlier studies, we observe a coherent rotation of fast axes in the western part of the Alpine chain, and a region of homogeneous fast orientation in the central Alps.  The spatial variation of splitting delay times is particularly interesting. On one hand, there is a clear positive correlation with Alpine topography, suggesting that part of the seismic anisotropy (deformation) is caused by the Alpine orogeny. On the other hand, anisotropic strength around the mountain chain shows a distinct contrast between western and eastern Alps. This difference is best explained by the more active mantle flow around the Western Alps. We discuss earlier concepts of Alpine geodynamics in the light of these new observational constraints. 
Using satellite altimetry and magnetometer to detect magnetic signals from ocean circulation
Authors: Hornschild Aaron , Saynisch-Wagner Jan , Irrgang Christopher , Thomas Maik
Published: March 2021

We present an application of satellite altimetry to estimate the magnetic signals from ocean circulation for their possible detection.

Due to the global wind-driven ocean circulations, electrically conducting sea-water moves through Earth's magnetic field and generates electromagnetic signals itself. These signals have already been successfully modelled, but they are still unidentified in observations, like the Swarm satellite magnetometer mission. However, the ocean-induced electromagnetic signals depend on temperature, salinity, and vertically integrated water transport, and therefore would provide an additional, interesting source of information and possible validation.

A combination of sea surface height measurements from satellite altimetry and in situ observations allows estimating current velocities by using the geostrophic approximation. With the resulting integrated electric current density, the magnetic signals from ocean circulation can be calculated using an electromagnetic induction solver.

Finally, the estimations are a basis for the separation of magnetic signals from ocean circulation in Swarm satellite magnetometer data. The key aspect of this separation is the predictability of the temporal behaviour of the magnetic signals from ocean circulation by the estimations from satellite altimetry. For this separation, we try to use a Kalman filter and impose the temporal behaviour of the magnetic signals from ocean circulation with the estimations from satellite altimetry. 

Here, we report on the status of the ongoing research about the use of satellite altimetry to detect the magnetic signals from the ocean circulation in magnetometer observations.
Developing prototype decadal climate prediction services
Authors: Dunstone Nick , Athanasiadis Panos , Caron Louis-Philippe , Doblas-Reyes Francisco , Frueh Barbara , Hermanson Leon , Lockwood Julia , Pankatz Klaus , Paxian Andreas , Reinhardt Katja , Scaife Adam , Smith Doug , Solaraju Balakrishnan , Thornton Hazel , Tsartsali Eirini
Published: March 2021

Here we present an overview of results emerging from a project to develop prototype decadal climate prediction services, funded by the EU Copernicus Climate Change Service (C3S). The field of interannual to decadal climate prediction has matured rapidly over the last ~15 years, becoming an established part of the Coupled Model Intercomparison Project (CMIP) process with multi-model decadal climate predictions made in CMIP5 and CMIP6 (DCPP MIP). It has further been highlighted by the recent creation of the WMO Lead Centre for Annual-to-Decadal Climate Prediction. Whilst these activities have led to rapid development in our understanding of decadal climate predictability and mechanisms driving global and regional annual to decadal climate variability, the creation of useful climate services on this timescale is still in its infancy.

This EU funded project was designed to start to address decadal climate services and brings together many of the key European institutions involved in decadal climate predictions from four different countries: Germany (DWD), Italy (CMCC), Spain (BSC) and the UK (Met Office). Each partner is working with a different sector: infrastructure, energy, agriculture and insurance where they have been developing a prototype decadal climate service in partnership with a user in that sector. Here we report on the progress made so far and highlight a number of key lessons learned along the way. These include the use of both large multi-model ensembles and more predictable large-scale circulation indicators in order to give skilful regional predictions of user relevant variables. We also describe the development of a common product format to present forecast information to users, this contains essential information about the current probabilistic forecast, retrospective forecast skill and reliability.
Flood modelling in Tunisia: On the suitability of a large-scale hydrological model for flood forecasting at basin scale
Authors: Cantoni i Gomez Elia , Tramblay Yves , Dakhlaoui Hamouda , Thiemig Vera , Salamon Peter
Published: March 2021

Maghreb countries, like the rest of the Mediterranean region, are vulnerable to flood events which often cause disastrous damages and a large number of fatalities. In Europe, this problematic has been addressed by the implementation of the Copernicus European Flood Awareness System (EFAS) that, together with the national and regional flooding schemes, provide a robust tool for flood forecasting. Nevertheless, Maghreb countries do not have such national or regional flooding schemes and, although EFAS covers their northern territories, its forecast capability for these regions is limited as its hydrological model (LISFLOOD) remains uncalibrated due to data unavailability. As data become available, daily river discharge data of 21 Tunisian basins from 1980 to 2018 was used to implement and compare different flood modelling strategies including LISFLOOD and simpler models such as GR4J and IHACRES, which were calibrated for each basin separately. The LISFLOOD model was first implemented with its default parametrization to the 21 basins considered using both, the ERA5 dataset, and observed precipitation data from rain-gauges. Although the use of observations slightly increases the model performance, the performances achieved are substantially lower than with simpler calibrated hydrological models (i.e. GR4J and IHACRES); whereas these simpler models generally present KGE values over 0.4, just four out of the 21 catchments have positive KGE values when discharge is simulated with LISFLOOD.

The model sensitivity to six of its main parameters (Xinanjiang, preferential flow, upper groundwater time constant, lower groundwater time constant, percolation and Manning’s coefficient) was assessed through the application of the Latin hypercube sampling (LHS) scheme. The LHS was used to generate 1000 near-random samples of LISFLOOD parameters sets, to investigate the model sensitivity to these parameters within the 21 basins. This process was repeated constraining the parameter range progressively in order to achieve an optimal parameter set for each catchment, as well as an additional parametrization that could be used in all catchments while resulting into satisfactory performances. Additionally, a Sobol sensitivity analysis was conducted to further investigate the sensitivity of the parameters mentioned above. This analysis revealed that, for extreme discharge values, for extreme discharge values, the most sensitive parameters are the Upper and Lower groundwater time constants and the exponent in Xinanjiang equation for the soil infiltration capacity. Different calibration and validation experiments were carried out with different objective functions, in order to identify the best parameters sets suitable for flood modelling at regional scale.  
Unstable Periodic Orbits Sampling and Its Applications to Climate Models
Authors: Maiocchi Chiara Cecilia , Lucarini Valerio
Published: March 2021

Climate can be interpreted as a complex, high dimensional non-equilibrium stationary system characterised by multiple time and space scales spanning various orders of magnitude. Statistical mechanics and dynamical system theory have been key mathematical frameworks in the study of the climate system. In particular, unstable periodic orbits (UPOs) have been proven to provide relevant insight in the understanding of its statistical properties. In a recent paper Lucarini and Gritsun [1] provided an alternative approach for understanding the properties of the atmosphere.

In general, UPOs decomposition plays a relevant role in the study of chaotic dynamical systems. In fact, UPOs densely populate the attractor of a chaotic system, and can therefore be thought as building blocks to construct the dynamic of the system itself. Since they are dense in the attractor, it is always possible to find a UPO arbitrarily near to a chaotic trajectory: the trajectory will remain close to the UPO, but it will never follow it indefinitely, because of its instability. Loosely speaking, a chaotic trajectory is repelled between neighbourhoods of different UPOs and can thus be approximated in terms of these periodic orbits. The statistical properties of the system can then be reconstructed from the full set of periodic orbits in this fashion.

The numerical study of UPOs thus represents a relevant problem and an interesting research topic for Climate Science and chaotic dynamical systems in general. In this presentation we address the problem of sampling UPOs for the paradigmatic Lorenz-63 model. First, we present results regarding the measure of the system, thus its statistical properties, using UPOs theory, namely with the trace formulas. Second, we introduce a more innovative approach, considering UPOs as global states of the system. We approximate the exact dynamics by a suitable Markov chain process, describing how the system hops on different UPOs, and we compare the two different approaches.  

[1] V. Lucarini and A. Gritsun, “A new mathematical framework for atmospheric blocking events,” Climate Dynamics, vol. 54, pp. 575–598, Jan 2020.
A method for the analyses of carbon stable isotope and content of particulate inorganic carbon in inland waters 
Authors: Li Yajun , Meng Fanyong , Wang Baoli
Published: March 2021

Studies on particulate inorganic carbon (PIC) in inland waters are relatively scarce due to the low concentration of PIC which makes it difficult to be measured accurately. In other studies, a characteristic ratio of PIC in total suspended solids in the water column has been proposed to estimate the river PIC flux to the sea, and a titration method to measure the PIC fluxes in karst rivers has been reported. Therefore, we used the Gas Bench Ⅱ-IRMS coupled technique method to analyze the δ13CPIC and PIC concentration in inland waters. The method has the advantage of being suitable for the accurate determination of the isotopic composition of trace PIC samples.

The purging time and carbon content of samples are the important factors affecting experimental accuracy. This study proposed the optimal purge time and the lowest carbon content of the inland water sample. The samples in the experiment included laboratory calcium carbonate standard (99.95 % purity) and PIC samples from the Wujiang River. The PIC samples from Wujiang River were collected on glass fiber filters. Datasets from the experiment demonstrated that the ideal purge time is 500-700 s, and at least 25 μg C should be included in the sample. The instrument signal value is low and the isotopic value fluctuates widely when the purge time is less than 500 s. The phosphoric acid cannot be injected into the sample bottle due to the high pressure in it when the purge time is more than 700 s. Therefore, a purging time of 600 s was used for the field sample analyses. The peak area displayed by the device is correlated with the carbon content in the sample, and the datasets show a good linear relationship between the peak area and carbon content in the sample when the sample be analyzed contained more than 25 μg of inorganic carbon. The carbon content of the sample can be calculated from the peak area of the same batch of calcium carbonate standard. While the peak signal is too low to detect the sample accurately when the C content is less than 25 μg. Therefore, the sample should contain more than 25 μg for the field sample analyses. This study will help to provide a reference for the method of determining the PIC content and isotopic composition in inland water.
Infiltration processes in karst aquifers affected by large-scale forest disturbances
Authors: Vilhar Urša , Ferlan Mitja , Kermavnar Janez , Kozamernik Erika , Marinšek Aleksander , Petrič Metka , Pipan Tanja , Žlindra Daniel , Ravbar Nataša
Published: March 2021

Karst systems represent 10–15% of land surface in the world and supply around 25% of the global demand for drinking water. In Slovenia karst areas are merely covered by forest and important for their rich and unique ecosystems. However, prevailing beech and mixed fir-beech forests in the region have been exposed to severe large-scale disturbances in the past few years, e.g., ice storms and heavy snow, windthrow, severe and prolonged periods of droughts and secondary insect damage, which have caused episodes of forest decline. Modification of the vegetation cover indirectly impacts the water balance. Despite the important role of karst water resources for supplying the population with drinking water, few studies exist that adequately evaluate the impact of predicted global changes on their quantity and quality. The effects of large-scale forest disturbances have been only marginally addressed, despite evaporation of water from the soil and epikarst being recognized as a significant process affecting hydrological cycle in karst regions. In many hydrological studies, the role and importance of vegetation in infiltration mechanisms, in particular the effect of trees and their root networks, has been widely neglected. In this study we present a holistic approach to infiltration processes research. An in-situ environmental monitoring network of the atmosphere-vegetation-soil-unsaturated zone of the aquifer has been designed to better understand infiltration in different compartments of the karst aquifer. Special focus is given to different forest development phases after large-scale disturbances and karst terrain morphology. The amount of precipitation in the open, canopy interception in mature forest and in canopy gaps with varying forest development phases, soil moisture and soil temperature are measured on the surface and subsurface. These measurements are performed in the area of an eLTER site Postojna-Planina cave system, i.e., on the top and bottom of karst depressions, while in the underground water discharge and electrical conductivity are measured in cave drips. By observing the time lag of the measured parameters to the recharge events, the effective infiltration of precipitation into the aquifer is evaluated and quantified. The results enabled to distinguish the recharge conditions under different forest development phases after large-scale disturbances and under different geomorphological conditions. The findings will in the later stage of the research serve as an input information for coupled vegetation-hydrological modelling of recharge conditions. Upscaling the modelling results from local to entire catchment scale would be useful for the evaluation of impacts of large-scale forest disturbance on the water balance of the entire karst aquifer system.
Basaltic mantle reservoirs from seismic inversion of reflection data 
Authors: Tauzin Benoit , Waszek Lauren , Yan Jun , Ballmer Maxim , Schmerr Nick , Afonso Juan Carlos , Bodin Thomas
Published: March 2021

Convective stirring of chemical heterogeneities introduced through oceanic plate subduction results in the marble cake model of mantle composition. A convenient description invokes a chemically unequilibrated mixture of oceanic basaltic crust and harzburgitic lithosphere. Such a composition is required to explain joint observations of shear and compressional waves reflected underneath transition zone (TZ) discontinuities1. The formation of basaltic reservoirs at TZ depth results from complex interaction between phase-change induced chemical segregation, subducted slab downward entrainment, and plume upward advection. However, the dominant mechanism to create and maintain the reservoirs is debated, because both present-day reservoir location and the amount of basalt in these reservoirs are unconstrained. Here, Bayesian inversion of SS- and PP-precursors reflection data indicates that the TZ comprises a global average basalt fraction f = 0.32 ± 0.11. We find the most enriched basaltic reservoirs (f = 0.5-0.6) are associated with recent subduction in the circum-Pacific region. We investigate the efficiency of plate subduction to maintain such reservoirs using global-scale thermochemical  convection models2.

[1] Waszek, L., Tauzin, B., Schmerr, N.C., Ballmer, M., & Afonso, J.C. (in review). A poorly mixed mantle and its thermal state inferred from seismic waves.

[2] Yan, J., Ballmer, M. D., & Tackley, P. J. (2020). The evolution and distribution of recycled oceanic crust in the Earth's mantle: Insight from geodynamic models. Earth and Planetary Science Letters, 537, 116171.
Experimental and numerical demonstrations for development of composite planar fabrics in fault zones
Authors: Miyamoto Takeshi , Hirono Tetsuro , Fuke Akari , Oohashi Kiyokazu , Yukawa Satoshi
Published: March 2021

Many experimental works have previously performed to understand frictional properties of various kinds of rocks and minerals by using friction apparatus at various orders of sliding velocities ranging from nm/s to m/s together with microscopic observation. However, friction experiments at wide range of velocities on a single type of rock or mineral have been rarely reported. Here we conducted friction experiments using powdered pyroclastic samples at velocities ranging from 0.0002 m/s to 1 m/s, 1.5–3.0 MPa normal stress, 10 m slip distance and dry and wet conditions. We also performed numerical simulation by using discrete element method (DEM) that focused on the changes of distances to adjacent particles (referred as CAP) and forces particles experiencing during frictional slip. At higher velocities, the sample showed relatively drastic decrease of friction coefficient and boundary-parallel Y shears. In contrast, R1 shears, oblique to shear direction, were observed in the samples at lower velocities. Numerical simulations at higher velocities of 0.1 and 1 m/s resulted in slip weakening and development of larger CAP lines parallel to boundary. At lower velocities, larger forces and CAPs were concentrated locally. These results could imply that the development of composite planar fabrics has a dependency on slip velocity. Now we are investigating the relationship using synthetic quartz powders, and will show the preliminary results of re-experiments, numerical simulations, and microscopic observations.
An elastic 3D Finite-Element-Model for Grímsvötn, Iceland
Authors: Greiner Sonja Heidi Maria , Geirsson Halldór
Published: March 2021

Deformation models are an important tool to study and monitor active volcanoes. However, in many cases models are strongly simplified either due to a lack of data or for the sake of speed and computational demands. The assumption of a magma body embedded in a homogeneous elastic half-space for example neglects the topography and heterogeneous crustal structures found at some volcanoes. This oversimplification can lead to a poor representation of individual systems and result in erroneous estimates of deformation source parameters like the location and geometry of a magma chamber.  The Finite Element Method (FEM) is a powerful tool to include complex heterogeneous structures and existing data sets into deformation models in order to create more realistic representations of individual volcanic systems.
In this study, the FEM-software COMSOL was used to build a three-dimensional elastic model of the subglacial volcano Grímsvötn, Iceland, accounting for the steep topography at the caldera rim, using a digital elevation model, as well as crustal heterogeneity. The elastic structure developed for this model is based on a density-structure, a seismic-velocity-structure and a pressure-dependent relation between the dynamic and static elastic moduli. The main feature of the elastic structure is a weak material (static shear modulus of Gstat=0.6-9.8 GPa from 1 km above to 2 km below sea level) filing the caldera, which is surrounded by a stiffer, ring-like structure underneath the caldera rim (Gstat=1.6-18 GPa from 1 km above to 2 km below sea level). The source parameters and geometry of forward models including the topography and elastic structure (individually and combined) were varied to fit the deformation observed at the nunatak GPS station GFUM, located at the caldera rim, during the last eruption (2011). While the topography has limited influence at the deformation at GFUM, the elastic structure requires the magma chamber to be significantly deeper than previous models suggested.
The effect of varying alkalinity in Mediterranean seawater on lightning flash intensity – An experimental approach
Authors: Silverman Jacob , Asfur Mustafa , Price Colin
Published: March 2021

The atmospheric phenomenon of lightning has been the focus of many studies in atmospheric physics and chemistry. In our laboratory investigations we have shown that the intensity of electrical sparks discharged into natural and artificial saline solutions are strongly influenced by their salinity and pH. We consider the radiative intensity of the laboratory generated electrical spark to be a scaled down replication of natural lightning and therefore define it as Lightning Flash Intensity (LFI). Based on the pH experiments it was suggested that a decrease in ocean pH due to ocean acidification corresponding to the predicted increase in atmospheric CO2 according to the IPCC RCP 8.5 worst case emission scenario, may increase the LFI by approximately 30±7% by the end of the 21st century relative to 2000. In that study, it was also shown that the acidification of seawater with a strong acid resulted also in a positive but weaker effect on LFI, suggesting that the alkalinity of seawater may also have an effect on it. Where, alkalinity is defined as the ability of seawater to resist a change in pH by addition of an acid (buffering capacity). In this study we tested the effect of changes in the alkalinity of Mediterranean seawater on its LFI by addition of concentrated HCl (alkalinity decrease) and NaOH (alkalinity increase). These treatments varied the alkalinity from its naturally occurring value of ca. 2600 to as little as 2100 and as much as 3000 µmole/kg. The additions of HCl decreased the pH of the seawater from its naturally occurring value of ca. 8.2 to a minimum value of 7.4 after equilibration with atmospheric CO2. While, the additions of NaOH increased the pH to a maximum value of 8.5. It should be noted that within the experimental range, the addition of HCl and NaOH did not have a measurable effect on the electrical conductivity/salinity of the seawater solutions. The results of these experiments showed that the LFI was strongly and positively correlated with alkalinity and was higher by ca. 40% at 3000 µmole/kg relative to its value at 2100 µmole/kg. These results imply that the alkalinity of natural waters may also be a strong predictor of LFI, especially in regions where there is a significant alkalinity input from external sources such as rivers and groundwater inputs or upwelling of alkalinity and CO2 enriched deep waters. Such regions could include the Mediterranean and North Seas as well as the intense upwelling regions off the west coasts of Africa and South America as well as South Africa. It is interesting to note that these regions also coincide with high densities of super-bolt events as previously shown.
Hard X-ray impact on the ionosphere D-layer: new results from VLF measurements
Authors: Briand Carine , Inturi Srivani , Cecconi Baptiste
Published: March 2021

The ionospheric electron density reacts to a change of ionization condition by a time delay Δt. Appleton (1953) demonstrated that this time delay is inversely proportional to the product of the electron density Ne and recombination rate coefficient α. Thus, the evaluation of the time difference between the peak time of VLF emission, which is supposed to represent the instant of maximum ionization, and the ionization source's peak time provides an easy way to estimate α Ne. First used to evaluate the increase of electron density at noon from H α peak emission, this technic was also employed to estimate the recombination rate during solar flares. The GOES Soft X-ray emissions (i.e. in the range 1.5-12keV) are then considered to determine the ionising source peak time.

Based on VLF measurements obtained from the SUPERSID antenna installed at the Meudon site of the Paris Observatory (France), we computed each flare's time delay from January 2017. We benefit from the events of September 2017, the strongest from the last 10 years. We thus demonstrate the prominent role of Hard X-Rays in ionizing the D-layer of the ionosphere.  
Dilatancy stabilises shear failure in rock
Authors: Aben Franciscus , Brantut Nicolas
Published: March 2021

Failure and fault slip in crystalline rocks is associated with dilation. When pore fluids are present and drainage is insufficient, dilation leads to pore pressure drops, which in turn lead to strengthening of the material. We conducted laboratory rock fracture experiments with direct in-situ fluid pressure measurements which demonstrate that dynamic rupture propagation and fault slip can be stabilised (i.e., become quasi-static) by such a dilatancy strengthening effect. We also observe that, for the same effective pressures but lower pore fluid pressures, the stabilisation process may be arrested when the pore fluid pressure approaches zero and vaporises, resulting in dynamic shear failure. In case of a stable rupture, we witness continued after slip after the main failure event that is the result of pore pressure recharge of the fault zone. All our observations are quantitatively explained by a simple spring-slider model combining slip-weakening behaviour, slip-induced dilation, and pore fluid diffusion. Using our data in an inverse problem, we estimate the key parameters controlling rupture stabilisation, fault dilation rate and fault zone storage. These estimates are used to make predictions for the pore pressure drop associated with faulting, and where in the crust we may expect dilatancy stabilisation or vaporisation during earthquakes. For intact rock and well consolidated faults, we expect strong dilatancy strengthening between 4 and 6 km depth regardless of ambient pore pressure, and at greater depths when the ambient pore pressure approaches lithostatic pressure. In the uppermost part of the crust (<4 km), we predict vaporisation of pore fluids that eliminates dilatancy strengthening. The depth estimates where dilatant stabilisation is most likely coincide with geothermal energy reservoirs in crystalline rock (typically between 2 and 5 km depth) and in regions  where slow slip events are observed (pore pressure that approaches lithostatic pressure). 
Early Pleistocene complex cut-and-fill sequences in the Alps
Authors: Dieleman Catharina , Christl Marcus , Vockenhuber Christof , Gautschi Philip , Akçar Naki
Published: March 2021

Deckenschotter (Cover Gravels in German) are Quaternary glacio-fluvial gravels, which unconformably overlie Tertiary Molasse or Mesozoic bedrock in the Northern Alpine Foreland. They comprise also the evidence of the Early Pleistocene glaciations. A significant phase of incision separated them into Höhere Deckenschotter (HDS: Higher Cover Gravels) and Tiefere Deckenschotter (TDS: Lower Cover Gravels) based on their topography. How the landscape evolved during Deckenschotter times is still not fully understood. The new cosmogenic nuclide chronology suggests that HDS deposited around 2 Ma and TDS around 1 Ma. In addition, 2 Ma old Deckenschotter are located at the same topographic elevation as the 1 Ma ones at Irchel (Canton of Zurich). This, indeed, points to cut-and-fill sequences and challenges the chronology based on the morphostratigraphy.

The aim of this study is to reconstruct the drainage patterns, base level changes, and thus the landscape evolution in the northern Alpine Foreland during the Early Pleistocene. Therefore, we focused on three Deckenschotter sites at Irchel and one in the area around Lake Constance. Sediments at these sites were analysed in detail to reveal their provenance, transport mechanism, depositional environment, and paleoflow regimes. Their chronology was established by isochron-burial dating. Our results indicate that the analysed sediments were transported from the Central and eastern Central Alps as well as from the Molasse to the foreland first by glaciers and then by rivers. They are deposited in a glacio-fluvial environment in the vicinity of a glacier. Based on the reconstructed chronology in this study and published cosmogenic nuclide ages, we propose that Deckenschotter are cut-and-fill sequences accumulated in three pulses between 2.5 Ma and 1 Ma. This cut-and-fill system implies that the regional base level was relatively constant during the Early Pleistocene. In addition, the depositional environment of Deckenschotter shows the presence of glaciers in the foreland. The 2.5 Ma old gravels, therefore, document the first advance of glaciers onto the Alpine Foreland. This seems to be synchronous with a first onset of glaciations on the northern hemisphere, which is assumed to occur at around 2.7 Ma.
Sedimentary breccias formed during extensional tectonics: facies organization and processes 
Authors: Kernif Tarik , Nalpas Thierry , Bourquin Sylvie , Gautier Pierre , Poujol Marc
Published: March 2021

Sedimentary breccias formed during extensional tectonics are spatially associated with large-throw normal faults. They result from the creation of a steep topography that becomes unstable, producing major rockfalls. The studied breccias, in Crete and in the Pyrenees, are up to 300 meters thick and are characterized by poorly sorted polygenic deposits of pebbles to boulders composed of highly angular plurimillimetric to plurimetric carbonate clasts. A lateral evolution is observed, with pebble-size clasts found near the normal fault and boulder-size clasts away from the fault. This evolution is related to the rockfall process as the total kinetic energy acquired by the small clasts during the fall is lower than that acquired by the bigger ones; as a result, the latter are able to travel farther. Interestingly, the fact that the smallest clasts are proximal while the bigger ones are more distal is contrary to the distribution found in alluvial fan systems, making it possible to differentiate from one another. The studied breccias commonly show disorganized layers and/or no noticeable layering across large distances. We interpret this feature as related to the movement on the normal fault, which progressively tilts the breccia layers and favours their gliding along the slope. Gliding is an important internal process to take into account in rockfall systems because it may disorganize the layering, create specific geometries like onlap around olistoliths, and produce deformation inside the breccia layers; the latter feature could be mistakenly interpreted as resulting from post-deposition regional deformation.

According to our observations, active normal faults with large throws provide the conditions for the formation and preservation of great volumes of sedimentary breccias through the following processes: i) footwall uplift, creating a pronounced topography with steep slopes, giving rise to major rockfalls, ii) hangingwall rapid subsidence, which allows the accumulation and preservation of the breccias without clast reworking by drainage systems. The latter is reinforced by the fact that, during the early stages of extension, the main watersheds point in a direction opposite to the fault slope whereas only small, discontinuously distributed watersheds flow in the direction of the fault slope. Upon ongoing extension, the size of these small watersheds increase. At one point, the sedimentary flow coming from these watersheds becomes more important than rockfall processes. Part of the breccia body is then eroded, reworked, and replaced by conglomerates of an alluvial fan deposited unconformably above the breccias.

Summing up, sedimentary breccias are readily formed as thick syn-tectonic deposits during early stages of extensional basin development. Thus, they may be considered as a typical lithology, and a marker, of continental extension.
Application of the theory of planned behavior with agent-based modeling for sustainable management of vegetative filter strips
Authors: Kasargodu Anebagilu Prajna , Dietrich Jörg , Prado Stuardo Lisette , Morales Bruno , Winter Etti , Arumi Jose Luis
Published: March 2021

An innovative socio-hydrological modeling framework for the development of environmental policies tailored to farmers' attitudes and economic interests is proposed with the inclusion of optimal environmental criteria. It focuses on modeling the complex relation of farmers, the environment, and the agricultural practices recommended by policy developers. An on-site survey of farmers is used to develop a behavior model based on a modified Theory of Planned Behavior (TPB). An agent-based model (ABM) is coupled with an agro-hydrological model for vegetative filter strips (VFS) to create dynamics of the social and environmental system.

The farmers from the Larqui river basin, Chile took part in the survey to understand their standpoint on the use of VFS to reduce soil loss in their agricultural fields and protect water bodies. The farmers were categorized into perceptive, proactive, bounded rational and interactive agents based on their answers to the survey. This categorization along with decision rules, and utility functions of agricultural activities including the VFS implementation and management are used to develop an ABM. Partial least square structural equation modeling (PLS-SEM) is used to analyze the modified TPB of farmers. Behavioral morality, behavioral willingness, knowledge of farmers showed a significant effect on modeling the intention and behavior of farmers to have VFS in their land. Subjective norm was the only construct that was not significant. The results of the ABM validate with the survey of the farmers. It shows that the decision on the width of VFS is not solely dependent on the utility generated and the reduction in soil losses but also on the behavior of farmers. This behavioral socio-hydrological modeling framework is capable of supporting policy-makers in developing tailored environmental policies that might improve the acceptance of sustainable agricultural practices by farmers.
Recent FerryBox observations reveal a strong increase in surface seawater pCO2 in the North Sea
Authors: Macovei Vlad , Voynova Yoana , Brix Holger , Petersen Wilhelm
Published: March 2021

Surface seawater carbon dioxide partial pressure (pCO2) in the North Sea, a large temperate shelf sea, was measured between 2014 and 2018 using FerryBox-integrated membrane sensors on ships of opportunity. The use of commercial vessels ensured a high spatio-temporal resolution, with data available year-round in areas belonging to all the stratification regime types found in the North Sea. Average annual cycles revealed a dominant biological control on pCO2 variability, with thermal effects modulating its amplitude. In the regions of freshwater influence, the biogeochemical characteristics of the riverine end-member also influenced the pCO2 measured near shore. Deseasonalized winter trends of seawater pCO2 were positive (ranging from 4.4 ± 2.0 µatm yr-1 to 8.4 ± 2.9 µatm yr-1 depending on the region), while the trends calculated including all deseasonalized monthly averages were even higher (ranging from 9.7 ± 2.8 µatm yr-1 to 12.2 ± 1.4 µatm yr-1). All these trends were stronger than the atmospheric pCO2 trend. Consequently, during our study period, the southern North Sea became a stronger source and the northern North Sea became a weaker sink for atmospheric carbon with implications for the Northwestern European Shelf carbon uptake capacity.
A vulnerability index for climate related risks in Sweden
Authors: Haas Jan , Karagiorgos Konstantinos , Nyberg Lars , Pettersson Andreas
Published: March 2021

Social vulnerability is mostly described as specific social inequalities in the context of a disaster. Following this understanding, empirical research focuses on the unequal exposure of different groups to disasters and/or on the unequal capacities of groups to anticipate, cope and recover from the impact of a hazard. Although social vulnerability has recently gained attention in academia, Sweden lacks frameworks and indicators to assess it at a national level.

Following the large amount of publicly available data in Sweden, to address this gap, we present a method for quantifying social vulnerability to climate risks in Swedish municipalities. A large number of variables were collected and analyzed to create quantitative indicators that purport to measure a municipality’s vulnerability. Using Principal Component Analysis (PCA), the information in the variables was reduced to a smaller number of components and socioeconomic vulnerability scores for each Swedish municipality. The factor analysis resulted in five components explaining more than 75% of the total variance. The resulting components and the final index are mapped for each municipality.

The results show that socio-economic vulnerability is not evenly distributed across Sweden. Apart from those findings the fact that some municipal clusters are much more vulnerable than others, the developed method is a useful tool for comparing socio-economic conditions among municipalities and for identifying susceptible municipalities which are likely to face significant challenges in coping with future natural hazard events.

Preliminary results show similar trends of social vulnerability to natural hazards at a highly resolved spatial level of aggregation as comparted to municipal levels. As studies on social vulnerability are often data-driven and thus performed on larger administrative aggregations, the sub-set of socio-economic variables from Statistics Sweden used in this study was found useful in our approach. In order to explore social vulnerability in conjunction with coastal and fluvial flood scenarios, an interactive web map was created with ArcGIS Dashboards.
Basal speed and deformation velocity in an alpine temperate glacier from high resolution borehole tilt measurements and GNSS surface velocity observations
Authors: Roldan-Blasco Juan Pedro , Piard Luc , Gimbert Florent , Vincent Christian , Gilbert Adrien , Gagliardini Olivier , Tobaigekov Anuar , Walpersdorf Andrea
Published: March 2021

Basal sliding speed is a main component of glacier flow. However, acquiring direct observations of the velocity at the base of a glacier is a challenging task due to limited accessibility. One option consists in indirectly measuring basal speed by subtracting the internal deformation velocity from the velocity observed at the surface. Internal deformation has been mostly studied through annual surveys of borehole inclinometry that provide a snapshot of the internal velocity field of the glacier, while more recent efforts have installed continuously recording sensors at different depths. The former method provides a good resolution in depth, while the latter provides a good resolution in time, but few studies have provided both.

In this study we quantify basal speed variations at both short and long timescales through the combined analysis of one year of continuous half-hour sampled borehole tilt measurements and high resolution GNSS positioning. The instrumentation campaign has been done in the framework of the SAUSSURE project, in which we drilled five boreholes in the ablation area of Argentière Glacier, a temperate mountain glacier in the French Alps. The boreholes were positioned along the center flow line, and each one was equipped with an array of ~18 sensors that recorded the tilt and azimuth at different depths as well as water pressure at the bottom and middle depth. With this dataset we are able to investigate how melt season impacts the internal dynamics of the glacier, or how the sudden accelerations of the glacier after heavy storms events are shared between changes in internal deformation and basal speed ups. We find that the yearly averaged internal deformation profile can be well described using a two dimensional Glen flow law with exponent n ~ 3.4. We observe as well that deformational velocities can represent up to 60% of the total velocity, more than previously considered for Argentière Glacier. Our findings suggest that weekly accelerations, usually observed along raises in water pressure, are due to the increase of basal speed paired with a decrease in deformation, which suggests stress reconfiguration. We don’t observe journal cycles of deformation velocity, which would indicate that journal variations of glacier velocity are due only to changes of basal speed. In contrast, glacier acceleration during melt season at monthly timescales is accommodated by  deformation velocity and not by sliding.
Integrating drought indices and long-term weather forecasts with a dynamic Bayesian network for assessing water shortage risk – a case study in Taoyuan
Authors: Lee Shih-Yao , Tsai Mengchieh , Yu Hwa-Lung
Published: March 2021

Water scarcity, which is a critical issue worldwide, is exacerbated by geomorphic characteristics and highly uneven spatiotemporal distribution of rainfall in Taiwan. The annual water availability per capita in Taiwan is less than one-fifth of the world average despite the high annual rainfall. Hence, stable water supply and efficient water resources management are challenging tasks for related authorities, and a decision support tool is required for the optimal decision. This study proposes a risk assessment framework for water shortage based upon a dynamic Bayesian network. Standardized precipitation index (SPI), standardized runoff index (SRI) and long-term weather forecasts are included in the framework. Taoyuan, a northern city in Taiwan with rapid growth of population and industries, is particularly vulnerable to water shortage and thereby chosen as our study site.
Transport of isoprene and its oxidation products by deep convective clouds in the Amazon
Authors: Bardakov Roman , Thornton Joel , Riipinen Ilona , Krejci Radovan , Ekman Annica
Published: March 2021

Transport of organic trace gases by deep convective clouds plays an important role for new particle formation (NPF) and particle growth in the upper atmosphere. Isoprene accounts for a major fraction of the global volatile organic vapor emissions and a significant fraction is emitted in the Amazon. We examined transport and chemical processing of isoprene and its oxidation products in a deep convective cloud over the Amazon using a box model. Trajectories of individual air parcels of the cloud derived from a large eddy simulation are used as input to the model. Our results show that there exist two main pathways for NPF from isoprene associated with deep convection. The first one is when the gas transport occurs through a cloud with low lightning activity and with efficient gas uptake of low-volatile oxidation products by ice particles. Some of the isoprene will reach the cloud outflow where it is further aged and produces low volatile species capable of forming and growing new particles. The second way is via transport through clouds with high lightning activity and with low gas uptake by ice. For this case, low volatile oxidation products will reach the immediate outflow in concentrations close to the values observed in the boundary layer. The efficiency of gas condensation on ice particles is still uncertain and further research in this direction is needed.
Climatology of dust deposition in the Adriatic Sea and biological response of Rogoznica Lake (central Adriatic)
Authors: Mifka Boris , Ciglenečki Irena , Telišman Prtenjak Maja
Published: March 2021

Airborne desert dust is one of the most abundant aerosols and an important factor in climate
change. After deposition in the sea, mineral dust acts as the nutrient. In this study, the climatology
of desert dust deposition in the Adriatic Sea was investigated with special reference to the possible
source and mineralogical characteristics of transported dust from North Africa. The effect is
particularly examined in unique, isolated marine system, Rogoznica Lake (RL; 43° 32 ’N, 15° 58’
E) through its biological response.
For that purpose, the MERRA-2 reanalysis data for dust deposition in the period 1989-
2019 were used. Annual dust deposition cycle in the Adriatic Sea has maximum in spring and fall
with stronger deposition in central and south. Wet deposition accounts for 63-92% of total
deposition and 75% of data contains less than 1.5% of the mass. Intensity classes are defined for
the remaining 25% and each refers to about 30% of the mass. On average, over 73 days per year
is of weak, 14.6 of moderate, and 3.65 of extreme intensity, which varies spatially. In order to
detect the specific synoptic patterns for the dust transport in relation to the dust sources activity
and deposition in the Adriatic Sea, the EOF analysis on 850 hPa was utilized. Positive or negative
mode phases correspond to deposition anomalies in the Adriatic Sea and can be related to particular
dust sources in North Africa.
Given the seasonal strong physicochemical stratification, relatively small volume, and only
source of freshwater and nutrients through precipitation during stratification, the Rogoznica Lake
proved ideal for monitoring desert dust deposition events, by monitoring nutrient concentration in
the surface layer (0–2 m). For the 2000-2012 period no correlation with MERRA-2 deposition
time series were found, but biological activity as a direct consequence of nutrient increase was
observed during deposition events. Since the Adriatic Sea was proved to be phosphate (P) and iron
(Fe) limited, the mineralogical database was used to estimate the amount of deposited P and Fe
during intense deposition events.