bluuebunny/crossref_metadata_2025 huggingface dataset:
A triggered seismic swarm below the city of Strasbourg, France on Nov 2019
Authors: Schmittbuhl Jean , Lengliné Olivier , Lambotte Sophie , Grunberg Marc , Doubre Cécile , Vergne Jérôme , Cornet François , Masson Frédéric
Published: March 2020

On Nov 12, 2019, a Ml3.1 earthquake was felt by the whole population of the city of Strasbourg, France. It was located by the BCSF-RéNaSS (EOST) in the northwestern part of the town (Robertsau area) at a depth of 5.5km. Its location in the vicinity of the deep geothermal wells (GEOVEN), the temporal correlation with the injection activity on site, the similarity of the depth between the bottom of the wells and  the hypocenter of the event, the lack of local seismicity before the event occurrence, the known geological structures including crustal faults in the area, immediately questioned the possible triggering of the event by the deep geothermal activities despite the relatively large distance (4-5km). In order to assess the origin of the Ml3.1 event, we report here on the data analysis performed from the seismological monitoring of the local area using the catalog produced by BCSF-RéNaSS and the regional public seismic networks. The main result is that the event is part of a remote triggered swarm that was initiated at least six days before the main shock and lasted more than two months. Template matching has been applied and allowed for a significant improvement of the detections. Double-difference relocations evidenced a set of conjugated faults in the swarm area that extends over 800m. Focal mechanisms of the two main events are very consistent with the known regional fault in the area. The regional stress field in combination with the fault orientation and a Coulomb failure criterion shows that the swarm location is in an unstable domain if the cohesion of the fault is weak, particularly sensitive to stress perturbations.
The metamorphic record of crustal assembly in the Paleoproterozoic Southeastern Churchill Province, Trans-Hudson Orogen, Canada
Authors: Godet Antoine , Guilmette Carl , Labrousse Loic , Smit Matthijs A. , Davis Donald W. , Vanier Marc-Antoine
Published: March 2020

Dating the onset of the continental collision and amalgamation of crustal blocks is at the basis of the reconnaissance of orogenic cycles and yields time constraints for the estimate of rates of accretionary processes over the last 4.5 Gyrs. The Paleoproterozoic Southeastern Churchill Province (SECP) represents the easternmost branch of the Trans-Hudson Orogen, squeezed between the Superior and North Atlantic Cratons (NAC). It comprises a collage of Archean to Paleoproterozoic crustal blocks (Core Zone), and two transpressive orogenic belts (New Quebec and Torngat Orogens), for which crustal amalgamation and associated collisional events are largely undated. We apply a multi-chronometer approach coupled with trace elements geochemistry on supracrustal sequences from the granulitic Tasiuyak Complex accretionary prism and the occidental margin of the NAC (upper plate) to estimate the timing of prograde, peak and retrograde metamorphism in the core of the Torngat Orogen. Our results yield to prograde garnet growth at 1885 ± 12 Ma (Lu-Hf), peritectic prograde monazite growth at 1873 ± 5 Ma (U-Pb), retrograde zircon growth during melt crystallization at 1848 ± 12 Ma, and rutile closure during slow exhumation at 1705 ± 5 Ma in the Tasiuyak Complex. Garnet from the NAC are dated at 2567 ± 4.4 Ma (Lu-Hf) and suggest that the granulite facies metamorphism in the NAC margin largely predates the Torngat Orogeny. We integrate the metamorphic record throughout the SECP to decipher its Paleoproterozoic tectonometamorphic evolution and propose a sequential collisional evolution from ~1.9 to 1.8 Ga.
Simulation of Critical Urban Climate Load Situations in Augsburg, Southern Germany, using PALM-4U
Authors: Straub Annette , Beck Christoph , Philipp Andreas
Published: March 2020

As part of the research programme "Urban Climate Under Change” [UC²] the project “Strategies for Reduction of Critical Urban Climate Load Situations in Augsburg” (MIKA) focuses on the application of the LES model PALM-4U to the medium-sized city of Augsburg, Southern Germany. The main objectives of the project include the model evaluation with special emphasis on three-dimensional observations of the urban boundary layer with unmanned aircraft systems but also utilizing ground-based long-term observations of multiple meteorological and air-quality variables. Furthermore, factors and mechanisms influencing the spatio-temporal evolution of situations with critical thermal load as well as high particulate matter concentrations within the city are investigated. Finally, the development, simulation and evaluation of short- and long-term strategies for minimization of these critical situations is another aim, carried out in cooperation with the city administration of Augsburg. Possible side-effects of these measures, e.g. remote effects in the surroundings of the city, are studied.

First model runs with PALM-4U for a test domain within the city of Augsburg have been carried out and are presented and discussed.
Improving the use of laser scanning intensity data in complex 3D mapping of the cave environment: Case study of the Gouffre Georges Cave, France
Authors: Nováková Michaela , Gallay Michal , Šupinský Jozef , Ferré Eric , Sorriaux Patrick
Published: March 2020

Terrestrial laser scanning (TLS) is frequently used for contactless acquiring of highly detailed and accurate three-dimensional (3D) representation of natural landscapes and man-made objects. The advantage of TLS has been exploited in mapping the underground landscapes such as caves formed in various geological settings with variable dimensions extending from narrow passage to grand domes. Highly detailed cave surveying with TLS generates millions of 3D coordinates of cave surface by which mapping of features difficult to be reached and studied directly is possible, e.g. speleothems, ceiling channels, structural rock properties and rock type alongside with the tectonic features influencing overburden stability. Besides the 3D coordinates, intensity of the backscattered laser pulse is recorded in the form of an additional attribute, influenced by various factors including spectral properties of the surface material. The studies published on the use of laser intensity have been mainly focused on the correction of intensity recorded by TLS for objects in the above-ground environment, where atmospheric attenuation, specifically humidity or dust content in the air, is negligible or it is considered constant during scanning. However, caves are specific due to their complex morphology and aerosol in their atmosphere. The presented case study focuses on these aspects in correcting the recorded intensity with a long range TLS Riegl VZ-1000 in the Gouffre Georges cave which formed on the contact of marble and lherzolite in the French Pyrenees. We present complex workflow for elimination of the influencing factors associated with the scanning geometry, including range and incidence angle, taking into account the character and contours of the cave wall surface as a set of facets and effect of atmospheric attenuation. The resulting corrected intensity value depends mostly on the spectral surface properties. Derived reflectance values revealed different lithological layers allowing to analyse their lithological and structural properties. Corrected intensity can be also used in biospeleological studies for mapping and quantification of cave fauna, in speleology for observing structures with higher occurrence of wet areas where active karst processes occur and even in archaeological studies for identification of cave paintings.
Tomographical field investigation of hydraulic properties of a fractured aquifer using active thermal tracer testing
Authors: Liu Quan , Hu Rui , Qiu Pengxiang , Tao Ran , Yang Huichen , Xing Yixuan , Ptak Thomas
Published: March 2020

Compared to porous media, fractured aquifers are generally characterized by a more pronounced hydraulic heterogeneity. To describe hydraulic properties of fractured subsurface, investigation methods such as hydraulic tests, tracer tests and hydrogeophysical tests have been widely used. In recent years, thermal tracer tests are obtaining more attention because thermal response signals can be easily and economically obtained at a high resolution, e.g. using distributed temperature sensing (DTS) systems. Some studies have even employed the travel-time-based thermal tracer tomography (TTT) to reconstruct the aquifer heterogeneity (Somogyvári M. et al., 2016; Somogyvári M. and Bayer P., 2017). In this study, we further develop and apply the TTT method for a field scale investigation of the hydraulic properties at a geothermal test site in Göttingen, Germany, equipped with five instrumented experimental wells.

Presently, using travel-time-based thermal tracer tomography to describe the hydraulic connectivity or conductivity is limited to the condition that the heat transfer must be convection dominated. Thus, the field experiments have to be divided into two steps. A full length well warm water injection test is firstly conducted to obtain information about the basic hydrogeological conditions, such as the fracture insertion depth and the connectivity between the wells. Subsequently, four multilevel thermal tracer tests are performed. The temperature changes in all five wells are recorded using a DTS system. Finally, based on the travel-time-based inversion method, the hydraulic conductivity distribution of the fractured aquifer can be obtained.

Preliminary test results showed that the orientation of transmissive fractures is mainly along the E-W direction at our test site. Given the good hydraulic connectivity, the first thermal tracer tomographical tests in a fractured aquifer were performed between two wells positioned along this direction. As next, we will work on the reconstruction of the fracture distribution between those two wells.
Borehole equilibration: testing a new method to monitor the isotopic composition of tree xylem water in situ
Authors: Marshall John , Cuntz Matthias , Beyer Matthias , Dubbert Maren , Kuehnhammer Kathrin
Published: March 2020

Forest water use has been difficult to quantify. One promising approach is to measure the isotopic composition of plant water, e.g.
the transpired water vapor or xylem water, which often differs from that of other water vapor sources. Traditionally such
measurements have relied on the extraction of wood samples, which provide limited time resolution at great expense, and risk
possible artefacts. Utilizing a borehole drilled through a trees’ stem, we propose a new method based on the notion that water
vapor in a slow-moving airstream approaches equilibration with the much greater mass of liquid water in the xylem. We present
two empirical data sets showing that the method can work in practice. We then present theoretical models estimating the
equilibration times and exploring the limits at which the approach will fail. Given long enough boreholes and slow enough flows,
the method provides a simple, cheap, and accurate means of continuously estimating the isotopic composition of the source water
for transpiration.
Young Uplift at the Eastern End of the Alps. Evidence for Uplift Unrelated to the Inversion of the Pannonian Basin?
Authors: Stüwe Kurt , Gradwohl Gerit , Bertosch Thorsten , Hohmann Konstantin , Robl Jörg , Liebl Moritz
Published: March 2020

The eastern end of the Alps features a series of low relief surfaces at elevations up to 2500 m. These surfaces have long been known to reflect uplifted planation surfaces that have not yet been dissected by fluvial processes and thus preserve a strong geomorphic disequilibrium. While their age would present a good handle on the age of surface uplift in the Eastern Alps, these surfaces are barely dated and their age is only indirectly inferred to reflect the Miocene and Pliocene uplift history. Recent geomorphological cosmogenic nucleide-based studies have shown that these surfaces may record up to 1000 m of surface uplift in the last 5 Ma. Such a distinct uplift event in the recent past is surprising and needs to be interpreted. Interestingly, this time frame appears not to be accompanied by crustal shortening and the standard hypothesis about the inversion of the Pannonian Basin as the underlying cause needs to be questioned. In order to get a better handle on the nature of this young uplift event and its overriding driver it is crucial to understand its spatial extent. However, much of the Eastern Alps was glaciated in the Pleistocene and currently several studies suggest that elevated low-relief landscapes were shaped by the glacial buzz-saw, instead of interpreting them in terms of fluvial prematurity of recently uplifted planation surfaces. The models of glacial erosion versus fluvial prematurity as the formation agent of the low-relief surfaces can be discerned if it can be shown that the surfaces formed prior to the Pleistocene. Here we report of a currently operating research project in which we employ cosmogenic nucleide burial dating on a substantial part of the entire Eastern Alps to derive the age of these surfaces. We use the burial age of siliceous sediments in caves formed at the phreatic-vadose transition as a proxy. Correlation of cave levels with low-relief surfaces and their mapping in the field is an integral part of the project.

 
From Elastic Deformation Loading Rates to Heat Flow Anomalies: Constraints on Seismic Efficiency and Friction Coefficient
Authors: Ziebarth Malte J. , Anderson John G. , von Specht Sebastian , Heidbach Oliver , Cotton Fabrice
Published: March 2020

A long standing debate in seismology revolves around the nonexistent heat flow anomaly across the San Andreas fault. Given the fault’s average slip rate and age, a strong San Andreas fault, i.e. characterized by a relatively high static friction coefficient of µ>=0.6, should produce a significant local heat flow anomaly across the fault [1]. Since the work of Lachenbruch and Sass [1], this anomaly has not been observed and although many possible causes for the lack of a heat flow anomaly have been explored, the static or dynamic weakness of the San Andreas fault remains a favorable explanation [2,3].

Recently, we have introduced the ENergy COnserving Seismicity (ENCOS) framework that relates elastic deformation energy loading rates to the long-term average energy release of the seismic process. Within the presented implementation of ENCOS for Southern California with an elastic loading rate between 300 MW and 1.9 GW, the two most significant parameters are the static friction coefficient and the average efficiency. In particular, they are the most significant sources of uncertainty in harnessing the GPS-derived strain rates and the stress data within the ENCOS framework.

Here, we show how ENCOS can be leveraged in combination with the constraints from heat flow measurements and observed seismicity to restrict the parameter space of the average efficiency and the static friction coefficient. This can help to reduce the uncertainty of the ENCOS model parameters, such as the elastic deformation energy loading rate, and opens a new viewpoint on the heat flow paradox.

[1] Lachenbruch, A. H., and Sass, J. H. (1980), Heat flow and energetics of the San Andreas Fault Zone, J. Geophys. Res., 85(B11), 6185–6222.

[2] Scholz, C. H. (2013). The Strength of the San Andreas Fault: A Critical Analysis. In Earthquakes: Radiated Energy and the Physics of Faulting (eds R. Abercrombie, A. McGarr, G. Di Toro and H. Kanamori).

[3] E. E. Brodsky et al. (2020), The State of Stress on the Fault Before, During, and After a Major Earthquake, Annu. Rev. Earth Planet. Sci. 48:2.1–2.26.
Calibration of direct normal irradiance (DNI) forecasts with quantile regression
Authors: Casado-Rubio Jose L. , Martínez-Marco Isabel , Yagüe Carlos
Published: March 2020

Direct normal irradiance (DNI) forecasts from two ensemble models, the global ECMWF-ENS and the limited area multimodel gSREPS, have been calibrated using the quantile regression method, taking DNI as the only input parameter to better understand the inner workings of the method. Forecasts for the southern part of Spain, with lead times up to 72 hours for ECMWF-ENS and 24 hours for gSREPS over a two-year period (from June 2017 to May 2019), have been used.

This study has focused on two particular aspects of the postprocess:

The effect of quantile regression on the spread of the models. The results show that the spread of ECMWF-ENS greatly increases after the postprocess, which has a positive effect on the accuracy of the model, with an improvement of 20% in the continuous ranked probability score (CRPS) after the calibration. However, this increase is uniform over the whole period, affecting equally to situations with low or high spread, hence the postprocessed forecasts are not able to detect changes in predictability. On the other hand raw gSREPS forecasts behave better during episodes of both low or high predictability. The postprocess does not significantly change the spread and accuracy of gSREPS.

The influence of the training sample. It has been found that DNI is a variable which can experience periods of low variability, particularly in regions like southern Spain, where long spells of sunny days are common. This has a sizeable impact on the performance of the quantile regression on certain days. Two study cases will be shown to illustrate this problem. Two possible solutions are proposed: use longer training periods (not always possible) or place restrictions on the value of the regression coefficients.
New station-specific limits in phenology to improve data quality during online-data-entry
Authors: Pietragalla Barbara , Füzér Linda
Published: March 2020

The Swiss phenology network operated by MeteoSwiss counts approximately 160 stations where up to 69 phenological events are observed by private persons. Currently, 68% of the observer transmit their data online by a recently developed tool called Phenotool. In order to reduce typing errors during the entry of the data, the values are instantly checked by Phenotool. The observer receives a visual warning if the data exceeds defined limits of an expected time-period giving him the opportunity to verify the date entered. The defined limits need to be as suitable as possible for each station and phenological event as numerous false warnings reduce the sensitivity of the observers and cause them to ignore the warning. 
Until June 2019, limits had been used for five altitudinal layers and for each phenological event resulting from the mean ± 2 SD (standard deviation) rounded to the nearest 10. However, for some stations these limits were not appropriate, therefore, we decided to calculate station specific limits as follows: The median and SD was calculated for each phenological series consisting of at least 10 observations. In a second step, the mean of all SDs < 20 days was calculated and 2.5 times SD added/subtracted from the median. This approach leads to the same range of the limits for each phenological event, while the start of the limits is specific for each stations depending on the previously calculated median. If we would have used a station-specific standard deviation, stations with high variability and often less accurate data, would have been “awarded” with a large range. 
For new stations, data-series consisting of less than 10 observations or deviant data-series, we calculated the limits with the mean standard deviations as described above and a predicted median from a linear regression model showing the relationship between the medians of a specific phenological event and the station heights. Deviant data-series were recognized by a difference larger than 30 days between modelled and calculated median.
The comparison of the old and new limits revealed that the newly calculated limits have an average range which is 8.52 days smaller. 55 out of the 69 phenological events have a smaller range, two has the same, and the remaining 12 have a larger range. Using the previous limits, in average 8.12% of the data from 1985-2019 was outside the defined ranges, however, applying the new limits results in 3.98% of the observations not fitting the limits. Considering the fact that the new limits have in average a smaller range, this improvement becomes even more significant. To conclude, we can say that the new limits produce clearly less warnings and more appropriate warnings in Phenotool enhancing data quality.
A portrayal of an orographic Warm Conveyor Belt using observations from aircraft, lidar and radar
Authors: Boettcher Maxi , Schäfler Andreas , Sodemann Harald , Sprenger Michael , Kaufmann Stefan , Voigt Christiane , Schlager Hans , Summa Donato , Di Girolamo Paolo , Nerini Daniele , Germann Urs , Wernli Heini
Published: March 2020

Warm conveyor belts (WCBs) are important airstreams in extratropical
cyclones, leading to the formation of intense precipitation
and the transport of substantial amounts of water vapour upward and
poleward. This study presents a scenario of a WCB that ascended from
western Europe towards the Baltic Sea using aircraft, lidar and
radar observations from the field experiments HyMeX and
T-NAWDEX-Falcon in October 2012.
Trajectories based on the ensemble data assimilation
system of the ECMWF are used to quantify probabilistically
the occurrence of the WCB and Lagrangian matches
between different observations. Despite severe limitations
for research flights over Europe, the DLR Falcon successfully
sampled WCB air masses during different phases of
the ascent. The overall picture of the WCB trajectories revealed
measurements in several WCB branches: trajectories
that ascended from the East Atlantic over northern France
while others had their inflow in the western Mediterranean
region and passed across the Alps. For the latter ones, Lagrangian
matches coincidentally occurred between lidar water
vapour measurements in the inflow of the WCB south,
radar measurements during the ascent at and its outflow
north of the Alps during a mid-tropospheric flight leg over
Germany.
The comparison of observations and ensemble analyses
reveals a moist bias of the analyses in parts of the WCB inflow
and an underestimation of cloud water species in the
WCB during ascent. In between, the radar instrument measured
strongly precipitating WCB air mass with embedded
linking trajectories directly above the melting layer while
orographically ascending at the southern slops of the Alps.
An inert tracer air mass could confirm the long pathway
of WCB air from the inflow in the marine boundary layer
until the outflow in the upper troposhpere near the Baltic
sea several hours later. This case study illustrates the complexity
of the interaction of WCBs with the Alpine topography,
which leads to (i) various pathways over and around
the Alpine crest and (ii) locally steep WCB ascent with increased
cloud content that might result in enhancement
of precipitation where the WCB flows over the Alps. The
combination of observational data and detailed ensemble-based
trajectory calculations reveals important aspects of
orographically-modified WCBs.
Sensitivity of seasonal hydrological predictability sources to catchment properties
Authors: Stergiadi Maria , Di Marco Nicola , Avesani Diego , Borga Marco , Righetti Maurizio
Published: March 2020

Seasonal hydrological forecasts are a powerful tool for water-related decision making associated to hydropower production, water supply and irrigation. The skill of these forecasts depends mainly on knowledge of the initial hydrologic conditions (ICs) on the start date of the forecast and knowledge of climate forcing (CF) during the forecast period. Identification of the sensitivity of the forecast skill to these two main predictability sources is crucial to funnel the efforts into improving the appropriate predictive tools, by either improving the ICs estimates or by enhancing the quality of the CF. This work aims at investigating the impact of catchment properties in terms of soil permeability on the contribution of the dominant predictability sources (ICs, CF) to the seasonal forecast skill. To this end, we apply the End Point Blending (EPB) framework to create forecasts with intermediate levels of uncertainty concerning ICs and CF. The methodology is applied in two catchments in the upper Adige River Basin that are representative of the two extremes of hydrological response: the Gadera catchment closed at Mantana (area: 390 km2, elevation range: 810–3050 m a.s.l.) that is highly permeable, hence slow-responding and the Passirio catchment closed at Merano (area: 402 km2, elevation range: 360–3500 m a.s.l.) that is characterized by low permeability, hence by a fast-responding regime. Our analysis highlights the contribution of each predictability source to the forecast skill over catchments of contradicting hydrological response, as well as the added value of the elasticity framework introduced by the EPB in comparison to the traditional ESP/revESP approach for identifying the sources of seasonal hydrological predictability in alpine areas.
Unstable Periodic Orbits Sampling in Climate Models
Authors: Maiocchi Chiara Cecilia , Lucarini Valerio , Gritsun Andrey , Pavliotis Grigorios
Published: March 2020

Unstable periodic orbits (UPOs) have been proved to be a relevant mathematical tool in the study of Climate Science. In a recent paper Lucarini and Gritsun [1] provided an alternative approach for understanding the properties of the atmosphere. Climate can be interpreted as a non-equilibrium steady state system and, as such, statistical mechanics can provide us with tools for its study.

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 characteristics of the system can then be reconstructed from the full set of periodic orbits in this fashion.

The sampling of UPOs is therefore a relevant problem for describing chaotic dynamical systems and can represent an interesting topic for the study of Climate Science. In this work we address this problem and present an algorithm to numerically extract UPOs from the attractor of a simple Climate Model such as Lorenz-63.

[1] V. Lucarini and A. Gritsun, “A new mathematical framework for atmospheric blocking events,” Climate Dynamics, vol. 54, pp. 575–598, Jan 2020.
Possible Generation Mechanism for Alfvenic Velocity Spikes and Magnetic Field Switchbacks as Observed by PSP
Authors: Zhu Xingyu , He Jiansen , Duan Die , Zhang Lei , Yang Liping , Hou Chuanpeng , Ying Wang
Published: March 2020

According to Parker's theory in the 1950s, the magnetic lines of force extending from the sun to the interplanetary appear to be Archimedean spirals. From 1960 to 1970, it was found that the interplanetary magnetic field not only follows the Archimedes spiral structure, but also has the characteristics of Alfvenic turbulence. How do these Alfvenic turbulence occur? What will be the characteristics when getting close to the Sun? Parker Solar Probe at 0.17au has found that there are often intermittent Alfvenic pulses (or called Alfvenic velocity spikes) in the solar wind. These pulses are high enough that the disturbed magnetic lines may even turn back. What's more interesting is that there is always a compressibility disturbance along with the Alfven pulse: the temperature and density inside and outside the Alfven pulse are different, the internal temperature is often higher than the external temperature, some of the internal density is higher than the external and some is lower than the external. The Alfven pulse often shows asymmetry on both sides: the magnetic field and velocity on one side are "clean" jumps, while on the other side are multiple small-scale disturbances of variables in the transition boundary layer. In view of this new phenomenon of magnetic field line switch back with compressed Alfven pulse, how it is generated is raising a hot debate. It is thought that the exchange magnetic reconnection of the solar atmosphere may be the underlying physical mechanism. But in the traditional exchange magnetic reconnection image, after reconnection, the zigzag magnetic field line can easily become smooth, which can not maintain the distortion of the magnetic field line, and may not be able to explain the observed Alfven pulses. In this work, we propose a new model called "Excitation of Alfven Pulses by Continuous Intermittent Interchange Reconnection with Guide Field Discontinuity" (EAP-CIIR-GFD). By analyzing and comparing the simulation results and observation results, we find that the model can explain the following observation features: (1) Alfven disturbance is pulse type and asymmetric; (2) Alfven pulse is compressible with the enhancement of internal temperature and the increase or decrease of the internal density; (3) Alfven pulse can cause serious distortion of the magnetic field line. Improvements to the model will also be discussed in the report.
Results of experimental tests for the evaluation of the signal-to-noise ratio, short-term stability, linearity in the time axis, and long-term stability of the GPR signal - according to COST Action TU1208 guidelines
Authors: Vrtunski Milan , Pajewski Lara , Ristić Aleksandar , Bugarinović Željko , Govedarica Miro
Published: March 2020

Ground Penetrating Radar (GPR) systems need to be calibrated on a recurrent basis and their performance shall be periodically verified, in accordance with manufacturer recommendations and specifications. Nevertheless, most GPR owners in Europe employ their radar units and antennas for years without ever having them verified by manufacturers, unless major flaws or issues become evident. In this framework, Members of COST Action TU1208 have recently carried out a critical analysis of the few existing procedures for the calibration and performance verification of GPR systems; and, they have proposed four improved experimental tests to evaluate the signal-to-noise ratio, short-term stability, linearity in the time axis, and long-term stability of the GPR signal [1]. In this work, we present the results of the tests executed in Novi Sad, Serbia, on a GSSI SIR 3000 control unit equipped with GSSI ground-coupled antennas having central frequencies of 400 MHz and 900 MHz. We have experienced that the execution of the tests helps to attain stronger awareness about the behaviour and limits of owned GPR equipment. It is also interesting to check how the results of the tests change over time and in different environmental conditions, to analyze the performance evolution of the equipment. Main aim of this abstract is to spread the voice and encourage GPR owners and manufacturers to execute the tests. If a wide variety of control units and antennas are tested, of older and more recent conception, with different numbers of working hours, reliable thresholds for the tests can be established and the proposed procedures can be further refined and upgraded. Moreover, the results of the tests can be translated into accuracy levels of measured physical and geometrical quantities, to get some awareness about the uncertainty of results of a GPR survey (e.g., achieved accuracy levels in the estimation of layer thicknesses).

 

[1] L. Pajewski, M. Vrtunski, Ž. Bugarinović, A. Ristić, M. Govedarica, A. van der Wielen, C. Grégoire, C. Van Geem, X. Dérobert, V. Borecky, S. Serkan Artagan, S. Fontul, V. Marecos, and S. Lambot, "GPR system performance compliance according to COST Action TU1208 guidelines,"  Ground Penetrating Radar, Volume 1, Issue 2, Article ID GPR-1-2-1, July 2018, pp. 2-36, doi.org/10.26376/GPR2018007.
PLANMAP data packaging: lessons learned towards FAIR planetary geologic maps
Authors: Brandt Carlos Henrique , Rossi Angelo Pio , Penasa Luca , Pozzobon Riccardo , Luzzi Erica , Wright Jack , Carli Cristian , Massironi Matteo
Published: March 2020

Geologic mapping is a key element of planetary exploration for mission planning, orbital and rover reconnaissance, and target selection for in-situ analysis and sample return, as well as for understanding the formation and evolution of planetary surfaces. The PLANMAP project (http://www.planmap.eu) aims at produce high-level, standardized geological maps of the Moon, Mars, and Mercury (Massironi M. et al., 2018). The project is integrating different types of data as images, spectral-cubes, chemical data, Digital Terrain Models and three-dimensional geological models to produce geological maps suitable to planetary exploration at different levels. The process results in rich datasets composed by a variety of datatypes encapsulated in open standards and released to the community as freely accessible packages (https://maps.planmap.eu).
To accomplish the complexity of deploying PLANMAP packages, considering reliability and automation as key components of a data release workflow, we arranged a data management framework respecting the FAIR (findable, accessible, interoperable, and reusable) guidelines. Geographic data are stored and served by a multi-layered Web-GIS allowing easy information discovery. Particular attention has been paid in designing the user interface and in the definition of the underlying data structure. Different data query services are also provided to properly address different user needs (Luzzi E. et al., 2020). PLANMAP’s datasets can be downloaded in the form of fully contained packages (https://data.planmap.eu) fulfilling a specifically designed standard. Once a data package is ready for publication, validation and summary information extraction take place and the results are published together within the packages.
We will here present an overview of the PLANMAP’s deployed data system, and the technical solutions that were adopted with the final goal of improving the quality standards of planetary geological maps.

References:

- Luzzi E. et al., 2020, “Tectono-magmatic, Sedimentary and Hydrothermal History of Arsinoes and Pyrrhae Chaos, Mars.”, EarthArXiv, doi:10.31223/osf.io/td297

- Massironi M. et al., 2018, “Towards integrated geological maps and 3D geo-models of planetary surfaces: the H2020 PLANetary MAPping project”, EGU General Assembly 2018
Underground city as a record for past geodiversity: a multi-approach for geoheritage promotion in urban areas
Authors: Melelli Laura
Published: March 2020

The “geological reason” of a city is always a proper starting point to understand the historical evolution of urban areas. However, where the human presence modified and covered the initial natural location is quite difficult to find outcrops for understanding the original geological and geomorphological arrangement. For this reason the underground cities is sometimes the unique opportunity to have meaningful records of the geological history of an area.

To have numerous and well-distributed anthropic underground cavities allows us to understand the palaeogeographic conditions preceding urbanization in an areal extent (spatial correlation). Moreover, if the excavation walls exhibit sufficiently complete and undisturbed vertical stratigraphic structures, the chronological sequence is present (timeline). Thus underground cities are ideal sites to learn the local geodiversity in space and in (past) time.

In addition, considering that in historical cities the most meaningful hidden cavities are focused in the downtowns, it is common to find a strong correlation between the geological value with the archaeological, architectural and historical ones. The union of different aspects increases the capability of these sites to be used as cultural attractors. With the aim to disseminate the concepts of geodiversity and geoheritage toward a wide audience, the underground cities became one of the best tool for scientists, administrators, teachers or touristic guides.

In this paper the Perugia city (Umbria, central Italy) is proposed as the test area, furthermore a conceptual scheme, in order to illustrate the best practice to use geodiversity as connection between urban geology and geoheritage promotion, is proposed.
Stability of fluorescence spectra of various water systems
Authors: Zoboli Ottavia , Peer Sandra , Saracevic Ernis , Tauber Joseph , Vybornova Anastassia , Zessner Matthias , Krampe Jörg
Published: March 2020

During the last years fluorescence spectroscopy was developed to be a fast and inexpensive way for water quality measurement in various water systems to characterize natural and human influenced water bodies regarding organic matter and contamination. Analyzing samples in a timely manner is crucial to gain valid and reproducible excitation emission matrix (EEM) data, but often difficult, specifically in transnational projects. In this project the shift of fluorescence spectra and other parameters over time is evaluated. Ten different ground-, creek- and river water, as well as wastewater treatment plant effluent samples were stored for more than 20 days. EEM data, as well as high pressure liquid chromatography (HPLC) spectra data and chemical standard parameters like pH, ORP (oxidation/reduction potential), TOC, NH4, NO3, NO2 and PO4 were measured daily and correlated. With this dataset the sample and fluorescence spectra stability were evaluated. Different mathematical and statistical methods, including Parallel Factor Analysis (PARAFAC) as well as novel statistical approaches, were applied for assessment of EEM and HPLC spectra. This further enables the direct comparison of the included analysis methods.
Acceleration of cold ions at separatrices of symmetric collisionless magnetic reconnection
Authors: Gordeev Evgeny , Divin Andrey , Zaitsev Ivan , Semenov Vladimir , Khotyaintsev Yuri , Markidis Stefano
Published: March 2020

Separatrices of magnetic reconnection host intense perpendicular Hall electric fields produced by decoupling of ion and electron components and associated with the in-plane electrostatic potential drop between inflow and outflow regions. The width of these structures is several local electron inertial lengths, which is small enough to demagnetize ions as they cross the layer. We investigate temperature dependence of ion acceleration at separatrices by means of 2D Particle-in-Cell (PIC) simulations of magnetic reconnection with only cold or hot ion background population. The separatrix Hall electric field is balanced by the inertia term in cold background simulations, the effect indicative of the quasi-steady local perpendicular acceleration. The electric field introduces a cross-field beam of unmagnetized particles which makes the temperature strongly non-gyrotropic and susceptible to sub-ion scale instabilities. This acceleration mechanism nearly vanishes for hot ion background simulations. Particle-in-cell simulations are complemented by one-dimensional test particle calculations, which show that the hot ion particles experience scattering in energies after crossing the accelerating layer, whereas cold ions are uniformly energized up to the energies comparable to the electrostatic potential drop between the inflow and outflow regions.
A Study on Parameters of Rainfall Runoff Model and The Prediction Method of Landslide Disaster in Mountainous Area
Authors: yoo Huimyeong , koyama Naoki , yamada Tadashi
Published: March 2020

This study is to analyze the evacuation behavior of residents living in the mountainous area and predict landslide disasters during heavy rain. 70% of Japan has are mountainous areas, and landslide disasters have occurred due to heavy rains caused by typhoons and heavy rainfall, etc. the annual average amount of damage caused by landslide disasters is 1000 in recent years. Also, landslide disaster warning information and evacuation information are important, it is difficult to predict landslide disasters, however, if we issued the evacuation advisory when the disasters already happened, there will be not enough time for the evacuation. In order to protect residents from such disasters, it is important to clarify "what information is effective for evacuation" and "when should those information be released?" Therefore, we conducted a survey on the residents in the mountainous areas which suffered from the heavy rain disaster in 2017 and analyzed the answers.

As a result, some residents evacuated before the evacuation information was issued. Because some landslide disasters occurred even before the first evacuation information was transmitted, and they felt danger. This result shows that the early information based on the prediction of the disasters is important in mountainous areas.

Therefore, we suggested a method for predicting landslide disasters, the method uses a rainfall and runoff tank model with high reproducibility and robustness of geological characteristics and uses the cumulative rainfall at the time of disaster occurrence as an index. As a result, this model predicted the occurrence of the landslide disaster 3 hours earlier by using forecasted rainfall. it is an effective method.
Passive-margin delta stratigraphy from source-to-sink numerical models: parametric studies and comparison with natural systems
Authors: Simon Brendan , Robin Cécile , Rouby Delphine , Yuan Xiaoping , Guerit Laure , Braun Jean , Guillocheau François
Published: March 2020

One major and under-appreciated aspect of coupled erosion-deposition numerical modeling is the ranges of input parameter values used to simulate natural source to sink systems without considering their meaning in term of erosion, transport and deposition processes. Most of the time, numerical models are used as a semi-inversion tool based on a “best-fit” approach, especially in its marine part where it aims to reproduce well-constrained sedimentary architectures which are great recorders of landscape evolution through time.

In this study, we performed several simulations using a new numerical landscape evolution model that accounts for both erosion and deposition onshore, as well as sediment deposition in the marine domain (Yuan et al., 2019; COLORS project, funded by Total). In the marine domain, sediment dynamic is described by a diffusion equation and the diffusion or transport coefficient has been calibrated from natural delta geometries. This model is highly efficient and allows the separation of the different processes involved and exploration of various setups and parameters values in order to address a large variety of questions. Its efficiency also allows inverse simulations that are powerful to determine the best possible scenarios in terms of climatic or tectonic reconstructions, or to determine the evolution of several key parameters.

In order to evaluate the model reliability to reproduce realistic sedimentary geometries, we explore the impact of perturbations in climatic, eustatic or tectonic parameters of the model on the stratigraphic architecture of passive margins shelf-edge deltas and discuss its feedbacks with the erosion dynamic of the onshore domain. This sensitivity analysis also allowed us to define the most relevant geometrical parameters of observed or theoretical stratigraphic architectures that have to be include in the misfit function of the inversions and optimization scheme.

This study is part of the COLORS project, funded by Total.
MHD simulations of an Uranus type rotating magnetosphere
Authors: Pantellini Filippo , Griton Léa
Published: March 2020

The characteristic relaxation time of the Uranus magnetosphere is of the order  of the planet's rotation period. This is also the case for Jupiter or Saturn. However, the specificity of Uranus (and to a lesser extent of  Neptune) is that the rotation axis and the magnetic dipole axis are separated by  a large angle (~60°) the consequence of which is the development of a highly dynamic and complex magnetospheric tail. In addition, and contrary to all other planets of the solar system, the rotation axis of Uranus happens to be quasi-parallel to the ecliptic plane which also implies a strong variability of the magnetospheric structure as a function of the season. The magnetosphere of Uranus is thus a particularly challenging case for global plasma simulations, even in the frame of MHD. We present MHD simulations of a Uranus type magnetosphere at both equinox (solar wind is orthogonal to the planetary rotation axis) and solstice (solar wind is orthogonal to the planetary rotation axis) configurations. The main differences between the two configurations will be discussed. 
Can a hydrological model be efficient and robust at the same time?
Authors: Royer-Gaspard Paul , Andréassian Vazken , Thirel Guillaume
Published: March 2020

It has been shown in various experiments that many conceptual rainfall-runoff models experience difficulties to simulate annual or longer-term variations of the streamflow (e.g. Coron et al., 2014). Whether this problem is inherent to the structure of the model in question or could be solved by a change of the calibration procedure is still a matter of debate: for example, the work of Coron (2013) tended to show that no parameter set able to solve the issue can be found, while Fowler et al. (2018) argued that such parameter sets exist, and should be identifiable by a change of objective function.

The aim of this study is to explore further the existence of such a parameter set in the case of the GR4J model (Perrin et al., 2003). Parameters sets were in particular tested against their ability to provide efficient (i.e. with good performance) and robust (i.e. transposable in time) discharge simulations over three flow ranges (low, mean and high flows). To this purpose, a large number of parameters sets of GR4J were sampled in 545 French and Australian catchments. The obtained performances were confronted to those obtained with automatic calibration with a range of objective functions focusing on diverse streamflow ranges.

Because of our large catchment set, we were able to identify a variety of cases: catchments for which highly robust parameter sets exist, catchments for which relatively robust parameter sets exist, and catchments for which no robust parameter sets can be found. Compared to the best sampled parameters sets, those derived through automatic calibration often yielded poorer performances regarding at the same time efficiency and robustness of the discharge simulations over the three flow ranges. We discuss the link between model failures and catchments characteristics, as well as the ability of the GR4J model to adequately simulate streamflow on different timescales and flow regimes.