bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance gains in an ESM using parallel ad-hoc file systems
Authors: Versick Stefan , Kirner Ole , Meyer Jörg , Obermaier Holger , Soysal Mehmet
Published: March 2020

Earth System Models (ESM) got much more demanding over the last years. Modelled processes got more complex and more and more processes are considered in models. In addition resolutions of the models got higher to improve weather and climate forecasts. This requires faster high performance computers (HPC) and better I/O performance.

Within our Pilot Lab Exascale Earth System Modelling (PL-EESM) we do performance analysis of the ESM EMAC using a standard Lustre file system for output and compare it to the performance using a parallel ad-hoc overlay file system. We will show the impact for two scenarios: one for todays standard amount of output and one with artificial heavy output simulating future ESMs.

An ad-hoc file system is a private parallel file system which is created on-demand for an HPC job using the node-local storage devices, in our case solid-state-disks (SSD). It only exists during the runtime of the job. Therefore output data have to be moved to a permanent file system before the job has finished. Quasi in-situ data analysis and post-processing allows to gain performance as it might result in a decreased amount of data which you have to store - saving disk space and time during the transfer of data to permanent storage. We will show first tests for quasi in-situ post-processing.
The observed impact of aerosols on cloud droplet formation during the RACLETS campaign
Authors: Georgakaki Paraskevi , Bougiatioti Aikaterini , Nenes Athanasios
Published: March 2020

The influence of aerosols serving as cloud condensation nuclei (CCN) on the production of droplets in mixed-phase cloud systems is an ongoing research problem that influences their optical and microphysical properties. During February and March 2019, the Role of Aerosols and CLouds Enhanced by Topography on Snow (RACLETS) field campaign collected unique and detailed airborne and ground-based in-situ measurements of cloud and aerosol properties over the Swiss Alps. This study presents analysis of the observed CCN activity of the aerosol, which combined with observed aerosol size distributions, can be introduced into a cloud droplet activation parameterization to investigate the drivers of droplet variability in these clouds. The implications for secondary ice production are then discussed.
Wind energy potential assessment in western Mediterranean
Authors: Patlakas Platon , Stathopoulos Christos , Gavriil Ariadni , Galanis George , Kallos George
Published: March 2020

Wind energy investments have met a quick growth during the last decades due to the stricter climate policies, the need for energy independence and the higher profits coming from the smaller costs of such applications. Moreover the evolution of technology leads to the characterization of more areas as suitable for energy applications. Offshore wind farms are a nice example of how to build bigger, more efficient and resistant in extreme conditions wind power plants.

The present work is focused on the determination of the suitability of an offshore marine area for the development of wind farm structures. More specifically the region of interest is the marine area on the south of France including the Gulf of Leon. For the needs of the study a 10-year database, produced employing state of the art atmospheric and wave models, is utilized. The wind and wave parameters used, have a spatial resolution of 6 km and a frequency of one hour.

Wind speed and power probability distribution characteristics are discussed in different heights throughout the domain. Particular locations are selected for a more comprehensive analysis. At the same time extreme wind and wave conditions and their 50-years return period are analyzed and used to define the safety level of the wind farms structural characteristics. The outcome could lead to a review of the area suitability for wind farm development, providing a new tool for technical/research teams and decision makers.
Field observation of hydroxy diacids in PM2.5 and insights into their formation from aliphatic diacids through heterogeneous oxidation
Authors: Cheng Yuk Ying , Yu Jian Zhen
Published: March 2020

Aliphatic dicarboxylic acids (DCA) are significant constituents of oxygenated organic aerosol. Laboratory studies indicated that the major heterogeneous oxidation product of aerosol-phase aliphatic DCAs was the corresponding hydroxy DCAs (hDCAs). In this work, we focused our field investigation on hydroxyl DCAs and report their ambient abundance in an urban environment, and their correlations with other measured aerosol species. Good correlations (R~0.5-0.9) were observed between DCAs and hDCAs, supporting the precursor-product relationships between the two as suggested by laboratory studies. Moderate to good correlations were also observed for DCAs/hDCAs with oxidant potential (Ox=O3+NO2) (R~0.5-0.9) and sulfate (R~0.2-0.8) in summer. Ox might act as a gas phase oxidant indicator, hinting hat gas phase oxidation might play a role in formation of hDCAs. The effect of estimated LWC and sulfate was examined and illustrated through the contour plots. It was found that the episodic formation of DCAs and hDCAs was more associated with high concentration of sulfate, suggesting commonality in their formation pathways. However, high hDCA was not always associated with high estimated LWC. Long range transport contribution might explain such an observation. More efforts are needed to understand the formation conditions and mechanisms for hydroxyl dicarboxylic acids.
Towards an Effective and Scalable Hybrid Data Assimilation for Hydrogeophysical Applications
Authors: Moradkhani Hamid , Abbaszadeh Peyman , Gavahi Kayhan
Published: March 2020

A number of studies have shown that multivariate data assimilation into the land surface models would improve model predictive skills. Soil moisture, streamflow and Evapotranspiration are among those environmental variables that greatly affect flood forecasting, drought monitoring/prediction, and agricultural production that collectively control the land and atmospheric system. However, land surface models most often do not provide accurate and reliable estimates of fluxes and storages and are subject to large uncertainties stemming from hydrometeorological forcing, model parameters, boundary or initial condition and model structure. Here, we present the state-of-the art data assimilation methods, covering the evolution of methods, discussing their pros and cons and introduce a novel approach that couples a deterministic four‐dimensional variational (4DVAR) assimilation method with an evolutionary ensemble filtering that together  significantly improve the estimation of storages and fluxes, hence better forecasting skill. The Evolutionalry Particle Filter with MCMC (EPFM) uses the Genetic Algorithm (GA) to effectively sample the particles to better represent the posterior distribution of model prognostic variables and parameters. This is followed by coupling EPFM and 4DVAR which results in a superior DA approach, the so-called Hybrid Ensemble and Variational Data Assimilation framework for Environmental systems (HEAVEN). The method explicitly accounts for model structural error during the assimilation process. The application of methods is presented for both flood and drought forecasting while utilizing the remotely sensed observations.
Numerical simulation of ion reflection by lunar crustal magnetic fields
Authors: Divin Andrey , Deca Jan , Lue Charles , Beliaev Roman
Published: March 2020

We investigate the dynamics of solar wind - Moon interaction by means of large-scale Particle-in-Cell (PIC) simulations in this study. Implicit moment PIC method and open boundaries are implemented in the code (iPIC3D) allowing to use large-scale domains in three dimensions. Even though the Moon has no global dipolar magnetic field, satellite magnetic field measurements at low-altitude (8-80 km) orbits discovered the presence of patches of intense remanent magnetization of the lunar crust. In order to simulate the scattering effect of the lunar remanent magnetic field we implemented an empirical proton reflection model based on low-attitude survey by the Chandrayaan-1 spacecraft [Lue, 2011]. In this study we focus on the day side effects only and thus do not resolve wake and limb effects. Reflected ions are found to create an energized population of particles in the solar wind and are responsible for sub-ion scale instabilities over the strongest anomalies with non-Maxwellian ion distribution functions.
Assessment of drought and heat coupling during summer using copulas
Authors: Russo Ana , Ribeiro Andreia , Gouveia Célia M. , Pires Carlos
Published: March 2020

Droughts and hot extremes constitute key sources of risk to several socio-economic activities and human lives throughout the world, and their impacts can be exacerbated by their co-occurrence. Moreover, their occurrence is expected to increase under future global warming. Therefore, understanding the drought-heatwave feedback mechanisms is crucial for estimating the risk of impacts associated with their compound occurrence.

 

Several studies have examined individual extreme events or analyzed how intense certain events where. Nevertheless, limited research has explored drought-heatwave dependence, mostly focusing on the contribution of low antecedent soil moisture or preceding precipitation deficits to summer hot extremes. In the latest efforts in assessing the interactions between hot and dry extremes, the development of models describing the joint behaviour of climate extremes is still a challenge.

 

Here we propose to assess the probability of summer extremely hot days in the Iberian Peninsula (IP) being preceded by drought events in spring and early summer, based on their joint probability distribution through copula theory. Drought events were characterized by the Standardized Precipitation Evaporation Index (SPEI) for May, June and July for different timescales (3-, 6- and 9-months). The Number of Hot Days per month (NHD) summed over July and August were considered to characterize hot extremes.

 

Asymmetrical copulas with upper tail dependence were identified for the majority of the IP’s regions (except in northwestern regions), suggesting that compound hot and dry extremes are strongly associated. Moreover, the transition from previous wet to dry regimes increases substantially the probability of exceeding summer NHD extreme values. These results are region and time-scale dependent: 1) northeastern, western and central regions were found to be the regions more prone to summer hot extremes induced by dryness; 2) southwestern, northwestern and southeastern regions are less prone.

 

This assessment could be an important tool for responsible authorities to mitigate the impacts magnified by the interactions between the different hazards.

 

Acknowledgements: This work was supported by project IMPECAF (PTDC/CTA-CLI/28902/2017). Andreia Ribeiro thanks FCT for the grant PD/BD/114481/2016.

 
Evaluation the freshwater-saltwater interface using geophysical and geochemical investigations within the single borehole
Authors: Hwang Seho , Shin Jehyun , Kim Yongje , Cho Sooyoung , Moon Sang-Ho , Yoon Heesung , Kim Yongcheol
Published: March 2020

The Korean peninsula has three sides facing the sea, and many monitoring wells for seawater intrusion observation installed along these coasts. The electrical conductivity (EC) profiles of these monitoring wells are found to vary greatly depending on the hydrogeological characteristics of the coast. The research area is located in Seocheon, Chungnam, where two wells are about 1.5 km away, one borehole is freshwater and the other boreholes have high electrical conductivity. In the well where the high electrical conductivity is measured, the electrical conductivity increases rapidly at a depth of about 90m. The well is located about 50 meters from the coast, and the change in water level reflects tidal changes well. We conducted a variety of field surveys and laboratory tests to clarify whether seawater intrusion occurred in the freshwater-saltwater boundary at the depth of about 90 m and whether the freshwater-saltwater boundary was affected by tides. Applied methods are electrical resistivity survey, geophysical well logging and geochemistry. The geophysical survey line was located along the coast centered on the well and measured every six hours. As a result of the survey, it was difficult to identify the change of electrical resistivity due to tidal changes in the lower alluvial zone, that is, the rock formation. These result indicates that the permeable fracture zones are rarely distributed in the rock below the survey line, so the change of the formation resistivity of according to the tidal change is very small. Geophysical well logs such as optical televiewer, spectral gamma log, and water quality logs (i.e., temperature, EC, pH, DO, and ORP) were measured, and groundwater samples were collected according to depth and analyzed for T, EC, pH, DO, ORP, and 222Rn. We found it difficult to identify permeability fracture zones in the temperature gradient and optical televiewer logs. The electrical conductivity is generally around 4,000 uS/cm and increase rapidly from about 90m to 48,000 uS/cm. The water quality logs and the analysis of groundwater samples showed pH range of about 7 to 7.5, DO of 7 to 14 mg/L, and OPR of -80 to 180 mV. pH does not change with depth, DO decreases slightly, and ORP decreases rapidly around the fresh-saltwater interface. The analysis of 222Rn shows that, to the median depth of the borehole, it is similar to the intensity of natural gamma rays and decreases rapidly across the lower freshwater-saltwater interface. Finally, we measured the electrical conductivity logs repeatedly at the interval of 30 minutes in the lower borehole where the freshwater-saltwater boundary was formed, and identified that the profiles of electrical conductivity change with tides.
High resolution climate information over Europe during glacial times using a dynamical downscaling approach
Authors: Velasquez Patricio , Raible Christoph C.
Published: March 2020

To understand the processes that govern the climate response and feedbacks, modelling paleoclimate states offers a unique possibility to have insights into the mechanisms that convert a modified forcing into climate changes. In spite of the benefit of using global climate models (GCMs) for reproducing other climate states, their spatial resolution insufficiently represents regional and local climates, especially over complex topography. In this study, we bridge this scale gap by using a dynamical downscaling with the regional climate model Weather Forecast Research Model version 3.8.1. that is driven by the fully coupled Community Climate System Model version 4. Focussing on the Alpine region, we obtain climate information at 2 km resolution at present-day (perpetual 1990 AD conditions), the Last Glacial Maximum (LGM, 21 kya) and Marine Isotope Stage 4 (MIS4, 65 kya). The benefit of the dynamical downscaling approach is illustrated by analysing the PD and LGM simulations with the proxy evidences. The orbital forcing response is assessed by the comparing MIS4 to LGM simulations. Since the height of the Laurentide and Scandinavian ice sheets may still have some uncertainties, we carry out two additional dynamically downscaled simulations where the thickness of the ice-sheets is modified to 66% and 125% of the LGM level.

Focusing on temperature and precipitation, we observe that the dynamical downscaling approach improves the representation of the Alpine climate agreeing the proxy evidences better than the GCM, especially during colder months. Furthermore, the MIS4 orbital forcing shows an increase of temperature over the Alpine region, in particular at low levels and during colder months. In addition, the precipitation is slightly increased over low-altitude areas, but strongly over the mountains, in particular in the western Alps during colder months. This increase of precipitation is the result of an increment of water content due to the temperature rise. The outcome of using different ice-sheet thicknesses shows that temperature remains almost unchanged but the precipitation patterns is modified showing differences over southwestern and northeastern Alps, especially during colder months. This change in the precipitation pattern is explained by the modification of the atmospheric dynamics over the North Atlantic and Europe, in particular by the orientation and the shift of the larger-scale wind patterns, i.e., wind stream and storm tracks.

In conclusion, we demonstrate that the regional dynamical downscaling is a valuable method for representing paleoclimates at a finer scale. Moreover, a different orbital forcing mostly impacts on temperature, especially during colder months. Whereas a modified thickness of the Laurentide and Scandinavian ice-sheets mainly impacts on precipitation pattern, in particular the southwestern and northeastern regions during colder months.
Efficient simulation of prompt elasto-gravity signals (PEGS) based on a spherical self-gravitating earth model
Authors: Wang Rongjiang , Zhang Shenjian , Dahm Torsten , Heimann Sebastian
Published: March 2020

An earthquake causes a sudden rock-mass redistribution through fault rupture and generates seismic waves that cause bulk density variations propagating with them. For a large earthquake, both processes can induce global gravity perturbations, whose signals propagate with the speed of light and therefore can arrive at remote stations earlier than the fastest elastic P wave. In turn, the gravity perturbations generate secondary seismic sources overall within the earth, a part of which can cause ground motion prior to the direct P wave arrival, too. Recently, these prompt elasto-gravity signals (Vallée et al. 2017) for large earthquakes like Tohoku 2011 Mw 9.1 have been detected in records of  broadband seismometers and superconducting gravimeters. Though the physics of the PEGS has been well understood, the tools used so far for a realistic modelling of them are complicated and computationally intensive. In this study, we present a new and rather simple approach that solves the full-coupled elasto-gravitational boundary-value problem more accurately, but no more complicated than to compute synthetic seismograms in a conventional way. Using the new tool, we simulate the PEGS of the 2011 Tohoku earthquake in both temporal and spatial scales, based on a realistic kinematic finite-fault source model. The temporal results show clearly how the ground motion is inspired by the gravity change in short- and long-term as well as how the combined PEGS behave at different epicentral distances from 400 to 3000 km. The spatial patterns of PEGS, especially that of gravity change, reveal the relationship between the PEGS and the focal mechanism. We also compare our simulation results with the predictions made before and with the observed waveforms and find a good agreement. Furthermore, we show particularly that the moment magnitude, rupture duration and focal mechanism of the 2011 Tohoku earthquake can be estimated robustly using the PEGS measured at a dozen selected stations, which could be helpful for the earthquake and tsunami early warning in the future.
Turbulent properties of CME-driven sheath regions
Authors: Fontaine Dominique , Kilpua Emiliya , Alalathi Matti , Palmerio Erika , Osmane Adnane , Moissard Clement , Yoradanova Emiliya , Hadid Lina Z. , Janvier Miho
Published: March 2020

We have analysed magnetic field fluctuations in sheath regions ahead of interplanetary coronal mass ejections (CMEs). CME sheaths are one of the key drivers of space weather disturbances, but their detailed structure and formation are relatively poorly understood. The level of magnetic field fluctuations in sheaths is generally much higher than in the ambient solar wind. We compare fluctuation properties in different parts of a sheath observed at the orbit of Earth using by the Wind spacecraft. Our findings show that in general the transition from the preceding solar wind to the sheath generates new fluctuations that are mostly compressive and which increase intermittency.  Spectral indices are mostly steeper than the -5/3 Kolmogorov index. The standard p-model did not show a good fit (in either the Kraichnan or Kolmogorov form), but the extended p-model was in a very good agreement. This suggests that turbulence may not be fully developed in CME sheaths in general. Our study also reveals that turbulent properties can vary considerably between different sheaths and in different subregions of the sheath, and can be significantly modified by the presence of small coherent structures. The findings support the view that sheath formation is a complex process with multiple physical mechanisms playing a role in generating the turbulence. 
There-dimensional change detection in coastal cliffs using UAV and TLS
Authors: Hayakawa Yuichi S. , Obanawa Hiroyuki
Published: March 2020

Measuring three-dimensional morphological changes in rocky coasts is essential in protecting the 

coastal areas and evaluating the sediment dynamics therein. In this study, we carried out repeated 

measurements of the three-dimensional morphology of a small rocky island using terrestrial laser 

scanning (TLS) and unmanned aerial vehicle (UAV)-based structure-from-motion (SfM) 

photogrammetry for 5 years. The TLS-derived point cloud data is used to align the UAV-SfM point 

cloud with a better accuracy at a centimeters scale, for which iterative closest point (ICP) method was 

applied. Aligned UAV-derived point clouds were then compared each other to extract changed mass 

for each time period. The extracted point cloud of changed mass was converted to 3D mesh polygons, 

by which the total volume of eroded mass was calculated.

The temporal analysis of the point cloud revealed spatially variable rockfalls and wave cuts. The 

eroded mass volume for each period varied from 10.6 to 527.7 m3, which is equivalent to the horizontal 

erosion rates of 0.03 to 0.63 m/y. The temporal changes in the eroded volume is roughly associated 

with that in the frequency of high tidal waves (higher than 3 m) observed in this area. However, less 

correlation was found with the frequency of large ground shakes by earthquakes. The modern erosion 

rate is lower than the previously reported cliff retreat rates, but this suggests that the small island will 

disappear in decades. Three-dimensional structural analysis will also help understand the dynamic 

processes of the erosion of the bedrock cliffs in the island.
Imaging the Solar Corona during the 2015 March 20 Eclipse using LOFAR
Authors: Ryan Aoife Maria , Gallagher Peter T. , Carley Eoin P. , Morosan Diana E. , Brentjens Michiel A. , Zucca Pietro , Fallows Richard , Vocks Christian , Mann Gottfried , Breitling Frank , Magdalenic Jasmina , Kerdraon Alain , Reid Hamish
Published: March 2020

The solar corona is a highly-structured plasma which reaches temperatures of more than ~2MK. At low radio frequencies (≤ 400 MHz), scattering and refraction of electromagnetic waves are thought to broaden sources to several arcminutes. However, exactly how source size relates to scattering due to turbulence is still subject to investigation. This is mainly due to the lack of high spatial resolution observations of the solar corona at low frequencies. Here, we use the LOw Frequency ARray (LOFAR) to observe the solar corona at 120-180 MHz using baselines of up to ~3.5 km (~1--2’) during a partial solar eclipse of 2015 March 20. We use a lunar de-occultation technique to achieve higher spatial resolution than that attainable via traditional interferometric imaging. This provides a means of studying source sizes in the corona that are smaller than the angular width of the interferometric point spread function. 
Interaction with phosphate alters the environmental behavior of iron minerals: double eutrophication trouble?
Authors: Kraal Peter , Behrends Thilo , van Genuchten Case , Lenstra Wytze
Published: March 2020

Iron (oxyhydr)oxides (FeOx) such as ferrihydrite (Fh) and lepidocrocite (Lp) control the mobility of trace elements, contaminants and nutrients such as phosphorus (P) in aquatic systems. Conversely, the sorption of P can alter the structure and reactivity of FeOx. As such, elevated P concentrations in eutrophic, coastal aquatic systems may have far-reaching but currently poorly understood consequences for coupled Fe-nutrient cycling. Here, we present laboratory and field experiments to elucidate the effects of P incorporation on (i) FeOx structure and reactivity and (2) environmental FeOx transformations (crystallization, sulfidation). The structure of the FeOx, synthesized in the absence or presence of P (‘pure’ or ‘P-bearing’ respectively), was probed with synchrotron-based methods (X-ray absorption spectroscopy, high-energy X-ray scattering). Laboratory-based acidic and reductive dissolution experiments (abiotic and microbial) with pure and P-bearing FeOx were combined with novel in-situ field experimentation. The field experiments, which were conducted in freshwater and marine aquatic systems, involved gel-based diffusive samplers loaded with pure and P-bearing FeOx (Fh and Lp) to obtain detailed insight into FeOx chemistry and structure without interference from the sediment matrix. Results from FeOx synthesis experiments showed differences in the impact of P incorporation between FeOx. Ferrihydrite underwent only minor structural changes because of P sorption, yet these changes significantly destabilized the mineral, as evidenced by enhanced rates of reduction and dissolution. Incorporation of P during Lp formation resulted in FeOx precipitate that was significantly less structured than pure Lp. Field experiments in Fe(II)-rich freshwater sediment conducted with Fh showed relatively slow crystallization rates for Fh compared to published laboratory studies. This likely was the result of FeOx surface passivation by adsorption of pore-water P. In H2S-rich sediment, the degree of sulfidation was higher for P-bearing Fh compared to pure Fh, while the opposite was observed for pure and P-bearing Lp. These findings may be related to differences in electron transfer characteristics and surface reactions with sulfide between Fh and Lp. The novel field experiments provide detailed insight into natural FeOx dynamics in relation to environmental conditions. Decreased stability of FeOx formed in the presence of high nutrient concentrations, leading to less efficient retention of these nutrients, may represent an important feedback mechanism in eutrophication.
Modelling plasma turbulence observed by Parker Solar Probe during its first two orbits with hybrid-kinetic simulations
Authors: Franci Luca , Giroul Alice , Burgess David , Papini Emanuele , Chen Christopher , Del Sarto Daniele , Landi Simone , Verdini Andrea , Hellinger Petr
Published: March 2020

We employ 2D and 3D high-resolution hybrid kinetic simulations of plasma turbulence to explore the physical conditions encountered by the Parker Solar Probe (PSP) spacecraft during its first two orbits, modelling the turbulent cascade self-consistently from large fluid scales down to kinetic scales.
By varying key parameters (e.g., the ion and electron plasma beta, the level of fluctuations with respect to the ambient magnetic field, the injection scale), we explore different plasma conditions. We identify a new kinetic-scale regime with respect to what has previously been found in both hybrid simulations and spacecraft observations of the solar wind and of the near-Earth environment, characterized among other things by a steeper magnetic field spectrum. Our simulations reproduce PSP observations and thus offer the opportunity to investigate the physical mechanism(s) behind such change in the turbulent cascade properties. We discuss our results in the framework of theoretical models of the nonlinear interaction of dispersive wave modes, field-particle interactions, and magnetic reconnection in low-beta plasmas.
We also analyse intermittency, magnetic compressibility, polarization of wave-like fluctuations, and statistics of magnetic reconnection events by means of iterative filters, a new method for the analysis of nonlinear nonstationary signals.
Together with our previous numerical results in quantitative agreement with MMS observations in the Earth’s magnetosheath, our new findings confirm the ability of the hybrid approach to model in-situ observations, which is fundamental for interpreting observational results and for planning future spacecraft missions.
Structural framework and regional significance of the Northandean Cretaceous subduction cycle
Authors: Kammer Andreas , Avila Michael
Published: March 2020

The Northandean plate margin underwent a fundamental change in its structural configuration during a Cretaceous subduction cycle, as evidenced by the formation and accretion of a province of basic igneous arc rocks that gave rise to the basement of an Northandean Western Cordillera. Further north, this igneous terrane links to the Caribbean Large Igneous Province and has been associated, with respect to its origin, to an actively spreading ridge of the Farallon plate, implying a far-travelled origin with respect to Southamerica and calling for the existence of giant strike-slip faults. We challenge this allochthonous scenario by an alternative option of a forearc origin, invoking the possibility of a forearc opening by the forcing of a toroidal mantle flow at the northern end of the Andean trench, which would have introduced mantle material from the Pacific into the Andean realm through a Central American gap. Support for such an opening mode of a forearc basin comes from extensional tectonics, that accompanied the emplacement of the basic arc units and a concomitant subduction of the extrusive basic units at the inner border of this postulated forearc basin. This intraplate subduction comprises a distinct three-partite evolution: (I) Convergence first became manifest by the reactivation of a normal fault located within the supposed forearc basin and inboard of an inherited Triassic-Jurassic suture, but still failed at a crustal level. (II) A succeeding contractional stage involved the reactivation of the inherited Triassic-Jurassic suture and the tectonic erosion of a frontal compartment of the continental margin. After an incipient underplating, slivers of this continental compartment returned within a time span of about 20 Ma. (III) A final Late Cretaceous subduction stage evolved under the conditions of an oblique SW-NE oriented plate convergence and is characterized by extensional pulses, as may be concluded from the structural setting of the giant Antioquia batholith. In the Campanian subduction definitely locked, as evidenced by the regional buckling of the forearc realm and a rebound of the upper continental plate. Both onset and shutoff of this subduction cycle may be linked to deformation phases and are dated by syntectonic, fault-guided intrusions. This scenario of a forearc origin of the basic igneous province calls for the existence of two paired subduction zones: on its outer margin the subducting Farallon slab imposed a trench-parallel mantle flow and constrained an expansion of the forarc basin by slab rollback. On its inner margin, a secondary subduction compensated a surplus expansion of the actively forming forearc basin.
Falcon constructed artificial catchment for whole ecosystem manipulation how we build it and what are the first results
Authors: Bartiška Martin , Frouz Jan
Published: March 2020

Subsurface processes are often omitted in catchment studies here we presented artificial catchment as a new tool to study and budget these processes on catchment level.

Falcon is and artificial  catchment that build in Sokolov post mining sites Catchment consist from four separate micro catchments (pools) each ) 0.25ha in area and 2m in depth which are hydrologically isolated  and filled by post mining overburden. Two fields were levelled while in two was wave like surface was produced to mimic situation after heaping.  Leveled micro catchments were planted by alder (Alnus glutinosa).

Catchment allow to study meteorological variables, surface and subsurface runoff,  and other key ecosystem parameters (water table depth chemical composition of pore water, soil respiration, gas exchange between ecosystem and surrounding atmosphere using eddy tower etc.). First result show large erosion on waves then on levelled sites however large proportion of material eroded from flat site leave the site while in wave like surface most of it is trapped in depression between waves. Subsurface runoff form large proportion of total runoff in wavy sites than in flat sites. Stable water table established quickly in both types of catchments} few months after catchment establishment. Flat sites show higher initial diversity of plants.
Detection of aerosols in Antarctica from long-range transport of the 2009 Australian wildfires
Authors: Jumelet Julien , Tencé Florent , Keckhut Philippe , Bekki Slimane
Published: March 2020

We analyze the long-range transport to high latitudes of a smoke particle filament originating from the southern tropics main plume after the Australian wildfires now colloquially known as ‘Black Saturday’ on February 7th 2009. Using a high-resolution transport/microphysical model, we show that the monitoring cloud/aerosol lidar instrument operating at the French Antarctic station Dumont d’Urville (DDU - 66°S - 140°E) recorded a signature of those aerosols. The 532 nm scattering ratio of this thin aerosol structure is comparable to typical moderate stratospheric volcanic plume, with values between 1.4 and 1.6 on the 1st and 3rd days of March above DDU station at around the 14 and 16 km altitude respectively.

In this study, a dedicated model is described and its ability to track down such fine optical signatures at the global scale is assessed and validated against the Antarctic lidar measurements. Using one month of tropical CALIOP/CALIPSO data as a minimal support to a relatively simple microphysical scheme, we report modeled presence of the aerosols above DDU station after advection of the aerosol size distribution. The space-borne lidar data provide constraints to the microphysical evolution during the simulation and ensure reliable long-range transport of the particles as well as accurate rendering of the plume small-scale features below the 1°x1° resolution threshold.

This case study of smoke particle signature identification above Antarctica provides strong evidence that biomass burning events, alongside volcanic eruptions, have to be considered as processes able to inject significant amounts of material up to stratospheric altitudes. Among the questions arising out of this study, we highlight the occurrence and imprint of such smoke particles on the Antarctic atmosphere over larger time scales. Any degree of underestimation of the global impact of such deep particle transport will lead to uncertainties in modeling the associated chemical or radiative effects, especially in polar regions where many specific microphysical processes take place. Mainly through sedimentation, particle trapping above Antarctica may also impact the ground albedo (which is some of the largest in the world). Correlated to the smoke presence, we also report an associated ozone increase observed with the DDU ozone lidar. This feature only rarely been observed for events where pyroconvection is originally involved.
Tectonic evolution of the Mediterranean region from a global plate kinematics perspective: insights from a new deformable tectonic model
Authors: Agostini Simone , Otto Simon , Watson John , Howgate Roy
Published: March 2020

The tectonic evolution of the Mediterranean is well studied, but the models often cover a limited period of geological time and are not always placed in a wider context. Its evolution is linked to the surrounding African and Eurasian continents and their relative movements.

A new fully deformable tectonic model of the Mediterranean has been created as part of a proprietary plate model. This work has led to the identification of key global tectonic events influencing the development of the Mediterranean from the Early Permian to the present day. This first fully-deformable plate model of the Mediterranean enables to account for the shortening and extension that occurred in the area at a temporal resolution of 1 Ma. In most available plate models, plates are rigidly rotated back to their paleo-position, meaning they preserve their present-day size and shape. In some recent papers, the extent of deformation has been illustrated for selected time-slices, but these models cannot be considered to be ‘deformable’ because the deformation is not modelled in a continuous manner.

Following Hercynian orogenesis and until the break-up of Pangea, the Mediterranean was dominated by extensional tectonics along its southern margin, as a series small continental blocks rifted from the northern margin of Gondwana. The opening of the Central Atlantic in the Late Triassic-Early Jurassic led to displacement between Eurasia and Africa south of Iberia and the development of the Alpine Tethys, as the Atlantic initially propagated northwards to the east of Iberia. Rotation of Africa caused by the opening of the South Atlantic in the Late Jurassic-Early Cretaceous led to a ‘jump’ in spreading to the west, at the Iberia-Newfoundland margin. These larger scale plate motions overprinted the more local impacts of continued extension along the northern margin of Africa (e.g. Pindos Ocean). Opening of the North Atlantic once again changed the relative motion of Eurasia and Africa, and initiated a period of oceanic subduction and collision that culminated in the Alpine orogeny. Crucial to this story is the paleo-position of Apulia/Adria, which remained attached to Africa and was able to act as an indenter into Eurasia during the Alpine compression. Evidence for this connection will be presented and discussed.

 

 
Long-term incubations experiments: Insights about demethylation and role of methylmercury refractory pools
Authors: Baptista-Salazar Carluvy , Liem-Nguyen Van , Jonsson Sofi
Published: March 2020

Methylation and demethylation of mercury (Hg) control the concentrations of monomethylmercury (MeHg) in natural environments, and thus the pool of Hg available for biological uptake and food web biomagnification. Typically, Hg methylation and demethylation are studied in short-term incubation experiments (< 24 h) using isotopically enriched Hg tracers. This approach has been successfully used to e.g. identify environmental hotspots of both of these processes. However, as the tracers are typically added as dissolved Hg complexes, while most ambient inorganic Hg and MeHg in e.g. sediments and soils are adsorbed onto particles, rates are recognised to not reflect true methylation and demethylation rates of ambient Hg. The traditional approach also overlooks the potential existence of refractory MeHg pools, i.e. pools of MeHg not readily available for demethylation. Previous work has, however, indicated the potential role of refractory MeHg concentrations. Jonsson et al. (Nature Com., 2014), for example, suggest up to 70% of the MeHg pool in a brackish sediment system to be in a refractory form. The occurrence of this fraction is also suggested as a key factor mediating MeHg availability in sediments by DiPasquale et al. (Environ. Sci. Technol., 2000).

We have conducted long-term incubation experiments aiming to quantify refractory MeHg pools. In short, isotopically enriched Hg tracers (Me201Hg and 198Hg, pre-equilibrated with natural waters) were incubated with lake, marsh and brackish sea water sediments and forest soils at a temperature of 10 °C for up to 6 weeks. These samples represent contrasting environments with initial MeHg concentrations ranging from 0.01 to 3.9 ng g-1 dry weight, and MeHg:Hg ratios of 0.01 to 31%. To quantify refractory pools of MeHg, we will compare steady state concentrations of MeHg:Hg ratios for added MeHg tracer with the MeHg:Hg ratio of ambient Hg. In this presentation, we will discuss the results from this study, as well as the role of refractory MeHg pools.
High-resolution photogrammetric methods for nested parameterization and validation of a physical-based soil erosion model
Authors: Epple Lea , Kaiser Andreas , Schindewolf Marcus , Eltner Anette
Published: March 2020

Soil erosion is one of the most prominent environmental problems of major interest to a vast field of research. Due to the complexity, variability and discontinuity of erosional processes, erosion model approaches are non-transferable to different spatial and temporal scales.

The objective of our project is the across-scale modelling of soil erosion, using photogrammetric measurements and optimization methods as well as physical based model approaches. Present process-based models are only valid for the observation scale they are parametrized and validated for. In the observed reality phenomena therefore occur, which are not or only to some extent reproducible by complex model concepts (e.g. development of rills or concentrated runoff within driving lanes). We present the synergetic combination of a physically described model with highly redundant observations from photogrammetric data processing. This enables both the validation of the erosion model EROSION-3D as well as the optimization of its parameters and potentially advancement of the mathematical process description. The photogrammetric observations (RGB and thermal) offer the opportunity of a temporal and spatial differentiated process assessment (splash, sheet and rill erosion, as well as deposition and transport). To this purpose, the acquisition of the respective operating processes and contributing factors, will be nested defined at three different scales (micro plot, single slope and catchment scale) on two sites (loess soil and residual soil).

Flexible cross-scale applicable photogrammetric methods, considering 3D reconstruction and flow measurement, combined with physical-based methods of soil erosion modelling shall enable a better and reliable understanding of soil erosion processes on various spatial and temporal observation scales. Consequently, the implementation of the adjusted model is aimed for to enable a cross-scale description and validation of scale-dependent processes (e.g. discrete consideration of thin sheet flow and rill genesis) to offer new perspectives on both interconnectivity of sediment transport and relationship between event frequency and magnitude.
Fire effects on geomorphology: what can we expect with climate change?
Authors: Stoof Cathelijne
Published: March 2020

Climate change is expected to alter fire regimes but also rainfall patterns. Fire is a natural process that removes vegetation and may affect soil properties, resulting in changes in overland flow and streamflow generation. Some fires cause erosion and may even cause destructive debris flow and other events, which can not only threaten lives and property but also leave lasting imprints in landscapes. The geomorphological response after fire events is a complex function of pre-fire landscape and vegetation properties, fire behavior and effects, and post-fire rainfall timing, duration and intensity. In this talk, I highlight these processes using examples of past events, and explore geomorphological response to fires in a future where both fire and rainfall may be be rather different.

 
Linear predictability of Barents Sea ice cover: effects of coupling and resolution
Authors: Guo Chuncheng , Nummelin Aleksi
Published: March 2020

Wintertime Barents Sea ice cover has been strongly linked to heat transport through the Barents Sea opening and Barents Sea heat content. Previous studies have shown predictability at seasonal timescales with short lead times. However, studies that have used statistical prediction have focused on a small set of predictors in the vicinity of the Barents Sea. Here we will extend the analysis further south following the path of the Norwegian Atlantic Current and show that monthly predictability with lead times up to 1-2 years can be achieved in CMIP6 models using Climate Response Function (CRF's). We further examine the effects of model resolution and coupling in the predictability and compare the results to CRF derived from observations. Our results suggest that higher resolution generally leads to stronger predictability and the fully coupled system provides the most realistic response function. The ocean provides a narrow range of lead times corresponding to an advective timescale, while coupling to the atmosphere broadens the lead times that are important for prediction. Finally, we show that even the upstream sea surface temperatures provide relatively high predictability of the Barents Sea ice cover both in the models and in the observations.
THM Experiment for the Investigation of Freeze-Thaw Processes in Soils and Grouting Materials
Authors: Hesse Jan Christopher , Schedel Markus , Welsch Bastian , Sass Ingo
Published: March 2020

Freeze-thaw processes induced in the vicinity of borehole heat exchangers (BHE) as a result of operating temperatures below 0 °C can significantly affect the compound structure consisting of the BHE pipes, the cement-based grouting material as well as the surrounding soil. The hydraulic integrity of such systems is not ensured anymore and its thermal efficiency could be impaired. However, the knowledge on freezing and thawing processes in porous media, such as the grout and unconsolidated rock materials, is still incomplete. The content of unfrozen water has a strong impact on material properties influencing the overall heat and mass transfer processes. Moreover, freezing strongly depends on various boundary conditions such as soil type or pore water chemistry. Accordingly, it is essential to have adequate information about the freezing interval for different boundary conditions, which describe the transition from pure liquid water to the ice phase and vice versa.

Therefore, a thermo-hydraulic-mechanical (THM) experiment has been developed and is used to gain a more detailed insight into freezing processes in artificial grouts and unconsolidated rock materials. It consists of a modified triaxial test system, which can carry cylindrical samples with a diameter of up to 100 mm and a height of up to 200 mm. A confining pressure of up to 16 bar can be gained by a plunger system. The confining pressure liquid (water-glycol-mixture) can be tempered down to -25 °C and is used to induce freezing conditions on the lateral surface of the sample. Mechanical parameters such as the freeze pressure are recorded by an axial load sensor and a displacement sensor. Besides, the radial deformation can be observed by the volume displacement of the confining liquid. Moreover, the hydraulic conductivity of the sample is determined according to DIN EN ISO 17892 (2019). The fluid temperatures during the flow-through experiment can be varied between 5 °C and 25 °C to represent natural groundwater temperatures. In addition to that, the freeze-thaw experiment is equipped with an ultrasonic measurement device: In the observed temperature range, the wave velocity in solid particles is constant and not affected by temperature changes. However, with descending temperature, the ice content increases, which leads to an improved cross-linking of the solid soil particles. As a consequence, the bulk P-wave velocity increases with decreasing unfrozen water content. Hence, this relationship can be used to determine the content of unfrozen water during a freeze-thaw cycle.

At this time, the first experiments are conducted with this novel device. Consequently, initial results will be presented at the conference. Moreover, the results of the THM experiments will be implemented in numerical models, which allow for an upscaling of the experimental findings to real scale applications.