bluuebunny/crossref_metadata_2025 huggingface dataset:
Tomography image of double high-velocity heterogeneity beneath the Eastern Alps from the AlpArray data
Authors: Plomerová Jaroslava , Žlebčíková Helena , Hetényi György , Vecsey Luděk , Babuška Vladislav , Working Group the AlpArray-EASI , Working Group the AlpArray
Published: March 2020

Convergence between the European and African plates formed the Alps and the neighbouring mountain belts. We present results based on teleseismic body-wave data from the AlpArray-EASI complementary experiment (2014-2015, Hetényi et al., Tectonophysics 2018) and the AlpArray Seismic Network (Hetényi et al., Surv. Geophys. 2018). Tomography of seismic velocities in the upper mantle, as well as seismic anisotropy study along a ca. 200 km broad and 540 km long north-south transect (crossing the Bohemian Massif in the north, the East-Alpine root, and reaching the Adriatic Sea in the south), image the steeply northward dipping East-Alpine root, dominated by the Adriatic plate, steady southward thickening of the lithosphere beneath the Bohemian Massif and distinct regional variations of mantle lithosphere fabrics modelled in 3D. These characteristics imply complex, domain-like architecture of the collisional zone of the European/Adriatic plates beneath the Alps. Thanks to the close spacing of the AlpArray stations and high-quality data, the high-resolution tomography resolved for the first time two neighbouring high-velocity northward-dipping heterogeneities beneath the Eastern Alps, instead of one thick root of the lithosphere. The southern one, which we relate to the Adriatic plate, is more distinct, the northern one is less pronounced, it delaminates at ~100km depth and diminishes in direction toward the Central Alps. It may represent a remnant of an early phase subduction of the European plate with the switched polarity (relative to the polarity in the Western Alps), or a preceding phase of the Adriatic subduction.
A Pore-Scale Reactive Transport Model Approach for Investigating the Effect of Soil Physical Properties on Biogeochemical Processes
Authors: Golparvar Amir , Kästner Matthias , Thullner Martin
Published: March 2020

The vadose zone hosts a wide range of various microorganisms which provide different soil ecosystem services from nutrient cycling to biodegradation of harmful chemical substances. The efficiency of such in-situ biodegradation is influenced by different biotic and abiotic factors ranging from physical properties of the soil to the redox conditions controlled by the activity of the involved chemical compounds. One important feature of the soil system is the dynamical and simultaneous interplay of these factors, boosting or deteriorating the residing microbial community’s abundance and/or activity and hence shaping biodegradation of vadose zone contaminants. Physical properties of porous media – e.g. the pore geometry, pore size distribution, connectivity as well as the water content – play a major role in enhancing or restricting the bioavailable concentration of contaminants and other reaction partners. Pore-scale phenomena have been shown to be considerably affecting the macro-scale processes, therefore a quantitative bottom-top approach of these mechanisms in situ is adamant. Hence it is of paramount importance to understand the effect of soil physical properties on microbial activity and biodegradation of carbon compounds in soil.

Pore scale reactive transport processes have a complex, nonlinear dependency on the aforementioned factors, which severely challenges the experimental and/or numerical investigation of biodegradation at in in-situ conditions. However, the recent technological advances, specifically the imaging techniques, have made it easier to study biological and microbial evolution in porous media, but there is still a need for putting all these information together. For this purpose, numerical methods would offer the possibility of simulating a variable/controllable water saturation conditions and considering water/air dynamics and advective and diffusive micro-scale transport of all components in both, air and water phase, in porous medium structures directly obtained from CT scanned samples. Up to now, such pore-sale model approaches considering also the fate of biogeochemically reactive compounds are scarce. In this work we propose a novel reactive transport modelling technique combining the pore-scale numerical characterization of water flow and solute transport in unsaturated porous media and of biogeochemical process. For a variably saturated porous system, the presented model approach is solving the Navier Stokes equation and scalar transport equations for any arbitrary geometry and is simulating the dynamics of biogeochemical processes with any degree of complexity. Simulations are compared to experimental data to assess the effect of soil physical properties on the transport and degradation of contaminants in soil.
An analysis of the California earthquake insurance market since its early stages
Authors: Pothon Adrien , Guéguen Philippe , Buisine Sylvain , Bard Pierre-Yves
Published: March 2020

Despite California being a highly seismic prone region, around 85% of people are not covered against this risk. This situation results from more than 100 years of evolution since the first earthquake insurance cover after the 1906 San Francisco earthquake. To understand this evolution, two analyses have been performed: the first one at the market level and the second one at the insured people level.

At the market level, as many variables as the premium amount, the risk monitoring, the funding sources of prevention plans, the insurance company’s solvency and the attractiveness of earthquake insurance solutions, have been investigated. By cross-analysing data collected and analysing the evolution with time, three different phases have been identified in the earthquake insurance market history.

At insured people level, a database is built from 18 different data sources about earthquake insurance, gathering data since 1921. Next, a new model is developed to assess the rate of homeowners insured against this risk, according to their risk awareness and the average annual insurance premium amount.

These two analyses are finally used to investigate in which extent the California earthquake insurance market could reach again 40% of people insured, like in 1993 and 1996. Even if results show that a widespread belief that a devastating earthquake is imminent could bring such a situation, only a new earthquake insurance model will allow to achieve this goal in a sustainable way. In that respect, the efficiency of two current initiatives to bring more people to get an earthquake insurance: "Earthquake Brace and Bolt" and "JumpStart Recovery", is assessed at the light of the analyses performed previously in this paper.
Coupling Temperature Measurement and Stream Heat Budget Model to Evaluate Impact of River Restoration on the First-order Alpine Stream in Taiwan
Authors: Chiu Yung-Chia , Lee Tsung-Yu , Hsu Shao-Yu , Pan Ting-Xin , Huang Po-Syun
Published: March 2020

Distributed temperature sensing (DTS) is improving rapidly and provide opportunity for high spatial and temporal resolution. It has emerged as a unique and powerful tool for ecological application. The first-order stream of Chichiawan Creek in Taiwan is the crucial habitat for the endangered species of Formosan land-locked salmon, but the stream fragmentation, no surface streamflow, seriously reduced the salmon population, hampering the rehabilitation work. The utility of combining DTS, long-term water level data, temperature profiles, and electrical resistivity tomography (ERT) were demonstrated to comprehensive understand the exchange process beneath the first-order stream. Stream heat budget modeling with HFLUX has been developed through the field measurements along with local meteorological data and unmanned aerial vehicle (UAV) image to simulate the stream temperature and evaluate the exchange rate of energy gain and loss. The results show that the spatial and temporal variations of cold water inflows has been observed and the groundwater and hyporheic inflow have been differentiated using the statistical method. The significance of groundwater and hyporheic inflow can contribute certain amount of water as the ecological base flow at the downstream and reduce the water temperature during the summer time. If the river restoration is conducted to prevent the stream fragmentation, the model results indicate that the amplitude of daily stream temperatures can be reduced. Less stream surface and steeper stream slope are also projected to decrease stream temperatures. The quantitative evaluation method demonstrated here, based on extensive measurements and numerical models, is able to predict the precise level of impact of river restoration on the key environmental objective before actually conducting the efforts.
Linking regional changes in the intensity distribution of daily tropical precipitation to changes in large-scale circulation and convective inhibition
Authors: Chadwick Robin , Pendergrass Angeline , Berthou Segolene , Alves Lincoln , Moise Aurel
Published: March 2020

Global warming is expected to change the intensity distribution of daily tropical precipitation, with an increased frequency of heavy precipitation and reduced frequency of light precipitation. In general, this is likely to increase the risk of flooding, while also increasing the risk of long dry periods. However, on regional scales circulation change plays a major role in modulating this precipitation distribution change in climate model projections, so related climate change impacts will also be regionally dependent.

We propose a simple physical framework based on the dry static energy budget which explains regional daily precipitation distribution change in terms of changes in two physical drivers: large-scale circulation and time-mean convective inhibition (CIN). In this framework, increased CIN under global warming tends to reduce the frequency of convection, leading to a greater ‘recharge’ of instability between convective events, and consequently greater ‘discharge’ of latent heating (precipitation) during each event. Large-scale circulation regulates the speed of this recharge of instability via dry static energy flux convergence or divergence, and its change under warming is very regionally dependent. Changes in regional time-mean tropical precipitation are closely related to changes in large-scale circulation, so this framework also provides a physical link between changes in time-mean precipitation and changes in the daily intensity distribution of precipitation in each tropical region. 
Electric Field Sensor for Small Unmanned Aerial Vehicles
Authors: Chindea Stefan , Nicoll Keri
Published: March 2020

Characterisation of the vertical variation in the atmospheric electric field has been made for many decades, but normally in an ad-hoc manner, using instrumented weather balloons or manned aircraft, which are expensive to fly.  Such vertical measurements are required to measure the ionospheric potential and to characterise electric fields with clouds (both thunderstorm and non thunderstorm clouds) to understand the charging processes within them. 

Advances in electronics and battery technology has meant that small Unmanned Aerial Vehicles (UAVs) have now become available as a new science platform. These measurement platforms address many of the problems associated with manned aircraft while allowing in-situ measurements with an increased level of control and repeatability when compared to weather balloons. Despite their potential advantages, one of the main challenges to using UAVs for atmospheric electricity research is the lack of small, lightweight sensors which are commercially available. To overcome this barrier, this work describes the development of a lightweight, miniaturised electric field sensor to be integrated with a small UAV (<7kg, wingspan 2m). 

The sensor has been designed to allow measurements of the electric field intensities typical of non-thunderstorm low altitude (<6000 ft) clouds with a typical range of 0-2.5kV/m. It is based on the concept of an electric field mill, but with a translational shield rather than a rotating vane model. This allows the sensor to fit neatly within the wing of a small UAV, rather than the need to be mounted in the nose.  A custom designed 3D printed housing contains all elements of the sensor package, with the translational shield movement and data logging controlled by an onboard programmable microcontroller. This work will focus on the details regarding the experimental characterisation of the sensor package with a particular focus on the key influences of the integration with the airborne platform.
FAT tool: A decision support tool for disaster risk reduction in the Alpine Space
Authors: Poratelli Francesca , D'Amboise Cristopher , Neuhauser Michael , Accastello Cristian , Brun Filippo
Published: March 2020

The last decades have seen a higher attention payed to natural hazards due to the increasing losses and economic damages caused by them. Researchers, practitioners and local administrations studied the best way to mitigate and prevent them, using both structural and non-structural  defense techniques. Even though there are now several possible solutions to be used, it is not always easy for decision makers to choose the best option from both a technical and an economical point of view.

With the FAT tool we aimed at providing a useful mean for practitioners to help them choose between various protection options. The FAT tool is an online platform where the user, inserting a limited number of input data (e.g. slope profile, slope width, forest cover), is provided with an easily understandable output, that being a comparison of the costs and the benefits generated by different protection solutions.

The tool is built on an empirical, profile-based hazard model and deals with avalanches, rockfall and shallow landslides. The outputs of the hazard models are used to dimension and calculate the costs and benefits of several protection options and the damages avoided by those. The possible solutions considered are: ecosystem based solutions (e.g. protection forest), technical measures (e.g. snow fences, catching dams, rockfall nets), avoidance measures (e.g. road closure, building evacuation) and a combination of these. The most innovative part of the tool is the importance given to the role of the forest, and generally to the Eco-DRR solutions, on the hazard track, where a forest protection effect indicator is calculated to assess the effectiveness of a stand in mitigating the risk on the chosen profile. The outputs of the FAT tool, consisting in the index and the economic values of different alternative protection measures, can help the user identify the areas where the forests have the highest mitigation effect and choose where to allocate forest management resources.
Application of GPR in assessing of concrete dam structures health
Authors: Ristic Aleksandar , Bugarinović Željko , Vrtunski Milan , Govedarica Miro , Pajewski Lara
Published: March 2020

In this paper an application of GPR in the analysis of concrete structure is presented. Scanning is done as a part of preparation for mitigation works of dam ’Grančarevo’. The goal was to inspect existing small cracks and leakages. The dam is arc-shaped concrete dam with double curvatures. It is operational since 1968, and is situated 18km downstream from the wellspring of Trebišnjica river and 17km upstream from the town Trebinje, in Bosnia and Herzegovina. Relative height of the dam is 123m, while its width along the crown is 439m. Continuous monitoring of dam’s construction and surrounding terrain is conducted at over 800 measuring points. In order to determine precise position, geometry and propagation of cracks, this was the first time GPR was used.

GPR scanning was done on several important locations: on the crown, downstream face, internal galleries, down- and upstream walls, using antennas with 900 and 400MHz central frequencies. Based on scanning results, position and geometry of cracks within the concrete are successfully determined. Lateral scanning (on downstream face of the dam) are correlated with the results obtained on the crown. Also, at several locations, zones with higher humidity are noticed. These zones are significant since they present areas of higher priority during mitigation and they are often found in the vicinity of junctions between two concrete segments of the dam.

Obtained results indicate that GPR technology is rather useful tool for structure health monitoring which provides information that are significant in planning mitigation measures and extending a lifetime of a concrete object.

 
From research to applications – Examples of operational ensemble post-processing in France using machine learning
Authors: Taillardat Maxime , Mestre Olivier
Published: March 2020

Statistical post-processing of ensemble forecasts, from simple linear regressions to more sophisticated techniques, is now a well-known procedure in order to correct biased and misdispersed ensemble weather predictions. However, practical applications in National Weather Services is still in its infancy compared to deterministic post-processing. This paper presents two different applications of ensemble post-processing using machine learning at an industrial scale. The first is a station-based post-processing of surface temperature in a medium resolution ensemble system. The second is a gridded post-processing of hourly rainfall amounts in a high resolution ensemble prediction system. The techniques used rely on quantile regression forests (QRF) and ensemble copula coupling (ECC), chosen for their robustness and simplicity of training whatever the variable subject to calibration.

Moreover, some variants of classical techniques used such as QRF or ECC have been developed in order to adjust to operational constraints. A forecast anomaly-based QRF is used for temperature for a better prediction of cold and heat waves. A variant of ECC for hourly rainfall is built, accounting for more realistic longer rainfall accumulations. It is shown that forecast quality as well as forecast value is improved compared to the raw ensemble. At last, comments about model size and computation time are made.
Untangling fiber optic Distributed Temperature Sensing: Getting the right temperature and getting there smoothly
Authors: Schilperoort Bart , Lapo Karl , Freundorfer Anita , des Tombe Bas
Published: March 2020

Distributed Temperature Sensing (DTS) using fiber optic cables is a promising technique capable of filling in critical gaps between point observations and remote sensing. While DTS only directly measures the fiber temperature, it has been used to make spatially distributed observations of air temperature, wet bulb temperature, wind speed, and more, on the scales of centimeters to kilometers at temporal resolutions as fine as a second. Of particular interest for the flux community, the spatially distributed nature of DTS allows us to place point observations within a spatial context, highlighting missing physics and linking processes across scales.

However, DTS is not without its drawbacks. It is not a push button operation – each DTS array is unique, requiring an exceptional investment in time for the deployment and for turning DTS observations into physically-meaningful results. Characteristics of DTS observations change with the DTS device used, but also with, e.g., the type of the fiber, the layout of the fiber optic array, and properties of the reference sections used in calibration. These issues create two main challenges in processing DTS data: 1) the need for a robust calibration and 2) management of data that can exceed a terabyte, especially with large or long-term installations. To address these challenges and simplify the use of this powerful technique we present two tools, which can be used both standalone and in conjunction with each other.

First is ‘python-dts-calibration’, a Python package which is aimed at performing thorough calibration of DTS data, as calibration by DTS devices is often lacking in quality. It is able to perform a more robust calibration than the device default, and provides confidence intervals for the calibrated temperature. The confidence intervals vary along the fiber and over time and are different for every setup. The second tool, ‘pyfocs’, is a Python package meant for managing larger, long term installations. This tool automates the workflow including checking data integrity, calibration, and physically mapping the data. pyfocs incorporates ‘python-dts-calibration’ at its core, allowing the tool to robustly calibrate any DTS configuration. Lastly, the package provides the option for calculating other parameters, such as wind speed.

Both tools are open-source and hosted on GitHub[1][2], allowing for everyone to check the code and suggest changes. By sharing our tools, we hope to make the use of fiber optic DTS in geosciences easier and open the door of this new technology to non-specialists.

 

[1] https://github.com/dtscalibration/python-dts-calibration

[2] https://github.com/klapo/pyfocs
Holocene Water Isotope Records Not Reflecting Aridity Changes in Arid Central Asia
Authors: Liu Zhonghui , Jiang Jiawei , Wang Zheng , Krivonogov Sergey , Jiang Qingfeng , Hou Juzhi , Zhao Cheng , Zhou Aifeng , Liu Weiguo , Chen Fahu
Published: March 2020

Holocene moisture evolution in the arid Central Asia region, dominated by the westerly circulation system, has been shown to be in drastic contrast with that in Asian monsoonal regions. Yet, water isotope records, including stalagmite oxygen isotopes and terrestrial long-chain n-alkane/acid hydrogen isotopes, show many common features in the two regions. Here we present several new isotopic records from the arid Central Asia region to examine the isotopic differences from various archives/media, together with existing water isotopic records from both regions. Isotopic records more reflecting terrestrial signal in arid regions appear to follow the pattern in monsoonal regions, while those likely affected by isotopic enrichment due to lake water evaporation display various patterns, and not necessarily resemble moisture changes inferred from the same lakes. It thus appears that the terrestrial water isotopes in both regions may record the isotopic signature in precipitation, but not necessarily linked to aridity changes. Meanwhile, those isotopic records affected by lake evaporation, after subtracting the original precipitation isotopic signal, show good correspondence to moisture changes.
Heat and carbon changes in the ocean as a transient response and tool for decomposing heat uptake
Authors: Turner Charles , Oliver Kevin , Brown Peter , McDonagh Elaine
Published: March 2020

Whilst anthropogenic activities are significantly altering the climate, both warming the atmosphere and increasing CO2, the ocean is

significantly ameliorating both effects. This effect is so important that the transient climate response to carbon emissions (TCRE), can be

formulated primarily in terms of the ocean. We show that in direct analogy to the TCRE, Anthropogenic Carbon (Canth) and temperature increases in the ocean are

linearly related, both globally and integrated over a range of scales. These ocean responses are typically of order 0.02K/mumol/kg,

(equivalently ~80MJ/mol). This linear relation allows for direct translation between temperature and carbon inventory increases. Furthermore,

we are far better able to decompose DIC changes into Canth increases and that of other carbon pools, than we are decomposing heat

inventory changes into added and redistributed heat. By separating total DIC change into Canth and that of other carbon pools, we can therefore remove the effect

of the transient response relationship between heat and carbon. This allows the production of estimates of added and redistributed heat in the

ocean from remaining DIC changes. Our results suggest that the variability of the transient response is predominately set by heat uptake, not carbon, and that this

variability may be traced to individual water masses. Therefore, it may be necessary to separate this transient response regionally in order

to obtain accurate estimates of added and redistributed heat at a global scale using this technique. The Eulerian transient response is set

predominantly by isotherm heave. The part of the transient response set by climate sensitivity, analogous to a semi-Lagrangian approach, is

set largely by patterns of regional heat uptake.
Assessment of thermal water outflow plume in heterogeneous glaciofluvial deposits: a case study from Julian Alps, Slovenia
Authors: Serianz Luka , Rman Nina , Brenčič Mihael
Published: March 2020

In Alps, a number of thermal springs are known, which represent the outflow of thermal water from low temperature geothermal systems in fractured rocks. Such dynamics is usually characterized with convection flow, derived either by fault intersection or hydrogeological barrier where the thermal water is uprising due to hydraulic pressure imbalance. When the water is uprising due to convection, it is very likely that the mixing processes between the deep thermal component and the shallow fresh groundwater are established. In Bled case study in Slovenia, the thermal water with average temperature of 21.5 °C, which is around 12 °C higher than average annual air temperature, is discharging from fractured carbonate rocks into glacial Quaternary sediments. Since they have relatively higher but heterogeneous permeability, the uprising thermal water drains into these deposits and, consequently, forms thermal plume which is extending parallel to prevailing fresh groundwater flow direction. Knowing the extent of the thermal plume is of crucial importance for sustainable exploration of the geothermal resource, since it provides answers also to the key issues related to its geothermal and hydraulic characteristics and the dynamics of the regional flow of groundwater, including its recharge area. By approximating the thermal water outflow as a planar source (since we assume it springs out from a fault zone), a planar advective heat transport model (PAHM) was used to evaluate its geometry and quantify the rates. Nine scenarios were applied accounting for different dimensions of the heat source. Each scenario was verified by calculating relative error between the analytical model results and measured borehole temperatures. The PAHM proved to be a useful tool in applying heat transfer as a planar source in groundwater flow. Still, it is necessary to consider or to introduce relatively rough assumptions (e.g. simple model geometry) leading to a very conservative approach. The heterogeneity of the medium has a significant influence on the temperature distributions obtained with different simulation scenarios. Therefore, the calculated temperature distribution within a thermal plume is a subject to uncertainty. In addition, some small portion of a relative error can be attributed to Lake Bled, since the thermal plume is extending in the zone of lake water temperature fluctuation influence. Nevertheless, the analytical model can be used as a tool for simulating spatial distribution of the observed values acquired from field measurements and thus more correctly evaluating the average natural conditions.
Global observation-based climatology of precipitation occurrence and peak intensity
Authors: Beck Hylke , Westra Seth , Wood Eric
Published: March 2020

We introduce a unique set of global observation-based climatologies of daily precipitation (P) occurrence (related to the lower tail of the P distribution) and peak intensity (related to the upper tail of the P distribution). The climatologies were produced using Random Forest (RF) regression models trained with an unprecedented collection of daily P observations from 93,138 stations worldwide. Five-fold cross-validation was used to evaluate the generalizability of the approach and to quantify uncertainty globally. The RF models were found to provide highly satisfactory performance, yielding cross-validation coefficient of determination (R2) values from 0.74 for the 15-year return-period daily P intensity to 0.86 for the >0.5 mm d-1 daily P occurrence. The performance of the RF models was consistently superior to that of state-of-the-art reanalysis (ERA5) and satellite (IMERG) products. The highest P intensities over land were found along the western equatorial coast of Africa, in India, and along coastal areas of Southeast Asia. Using a 0.5 mm d-1 threshold, P was estimated to occur 23.2 % of days on average over the global land surface (excluding Antarctica). The climatologies including uncertainty estimates will be released as the Precipitation DISTribution (PDIST) dataset via www.gloh2o.org/pdist. We expect the dataset to be useful for numerous purposes, such as the evaluation of climate models, the bias correction of gridded P datasets, and the design of hydraulic structures in poorly gauged regions.
Large Scale TIDs climatology over Europe using HF Interferometry method
Authors: Blanch Estefania , Segarra Antoni , Altadill David , Paznukhov Vadym , Juan Jose Miguel
Published: March 2020

Travelling Ionospheric Disturbances (TIDs) are ionospheric irregularities that occur as plasma density fluctuations that propagate as waves through the ionosphere over a wide range of velocities and frequencies. It has been demonstrated that Large Scale TIDs (LSTID) can be detected with several ionospheric sensors such as ionosondes and their main characteristics such as velocity, direction of propagation and amplitude can be inferred.

We have applied the recent developed HF Interferometry (HF-Int) method to detect the occurrence and main characteristics of LSTIDs over Europe for different solar activities (2014 – 2019) in order to perform a climatological analysis. HF-Int determines the dominant period of oscillation and the amplitude of the LSTIDs using spectral analysis, and estimates the propagation parameters of the LSTIDs from the measured time delays of the disturbance detected at different sensor sites.

The results show that larger diurnal and seasonal occurrence of LSTID happens near sunrise hours and night-time, especially during equinox. In the morning sector, prevailing velocity propagation is westward influenced by the solar terminator effect and it also depends on the season: during winter the dominant propagation velocity is north-westward and during summer is south-westward. In the evening and night sector, the prevailing propagation velocity is southward suggesting auroral origin of the disturbance. The higher activity at night-time might be the result that neutral winds favour equatorward propagation at night whereas at day might prevent to propagate to low latitudes.

Similar behaviour has been found for high and low solar activity with the difference that during summer at low solar activity, large occurrence of sporadic E layer happens during day time. Then, ionospheric data experience large data gaps at the F region because of screening of the Es (Es Blanketing effect). This results in a poor statistic under such a conditions for daytime summer low solar activity and the number of detected LSTID is lower.
Guessing stone behaviour before extraction
Authors: Dias Luis , Silva Roberto , Lopes Luís , Candeias António , Mirão José
Published: March 2020

Natural Stone has always been one of the most widely used and appreciated materials in the construction of important structures, buildings and works of art. It is extremely important that the stone purchased by the consumer meets the expectations for which it was chosen, being colour one of the main aspects. Currently, there are companies with very high costs in the replacement of altered stone.

This work arises from the companies’ need to seek the extraction of stone blocks that ensure a lower susceptibility to colour change after application. To do so, a geochemical/mineralogical study was applied in a quarry located in the northern region of Lisbon, where one of the most important Portuguese lithotypes is currently explored. Featured by its excellent physico-chemical characteristics, this lithotype is further characterised by the coexistence of a blue and cream colour. The work aimed to study the presence of a mineral, pyrite, responsible for the natural discolouration of this construction resource.

The results obtained show a greater predominance of pyrite in the darker fractions of the rock, which increases while the exploration level is deeper.
Impact of mid-glacial ice sheets on the recovery time of the AMOC: Implications on the frequent DO cycles during the mid-glacial period
Authors: Sherriff-Tadano Sam , Abe-Ouchi Ayako
Published: March 2020

Paleo reconstructions such as ice cores have revealed that the glacial period experienced frequent climate shifts between warm interstadials and cold stadials. The duration of these climate modes varied during glacial periods, and that both the interstadials and stadials were shorter during mid-glacial compared with early glacial period. Recent studies showed that the duration of the interstdials was controlled by the Antarctic temperature through its impact on the Atlantic Meridional Overturning Circulation (AMOC). However, similar relation was not found for the stadials, suggesting that other climate factors (e.g., differences in ice sheet size, greenhouse gases and insolation) might have played a role. In this study, we investigate the role of glacial ice sheets on the duration of stadials. For this purpose, freshwater hosing experiments are conducted with an atmosphere-ocean general circulation model MIROC4m under early-glacial and mid-glacial conditions. Then, a sensitivity experiment is conducted modifying only the configuration of the ice sheets.  The impact of mid-glacial ice sheets on the duration of the stadials is evaluated by comparing the recovery time of the AMOC after the cessation of the freshwater forcing. We find that the expansion of glacial ice sheets during mid-glacial shortens the recovery time of the AMOC. Partially coupled experiments, which switch the surface winds between the two experiments, show that the differences in the surface wind cause the shorter recovery time under mid-glacial ice sheet. The wind shortens the recovery time by increasing the surface salinity and decreasing the sea ice at the deepwater formation region. Thus the results suggest that differences in the surface wind between mid-glacial and early glacial ice sheets play an important role in causing shorter stadials during mid-glacial period.
Wind erosion of microplastics from soils: implications for microplastic dispersal and distribution
Authors: Bullard Joanna , Ockelford Annie , McKenna Neuman Cheryl , O'Brien Patrick
Published: March 2020

Microplastics have potentially deleterious effects on environments and ecosystems.  The main research focus for translocation of microplastics has been via water, however recent studies of soils in the Alps and Middle East indicate airborne transport following wind erosion may also be significant.  This paper reports wind tunnel studies to determine the extent to which two types of low density microplastic (microbeads and fibres) may be preferentially transported from different substrates – a well-sorted quartz sand and a poorly-sorted soil containing 13% organics.  The polyethylene microbeads had a size range of 212-250 microns and density of 1.2 g cm3.  The polyester fibres were 5000 microns long and 500-1000 microns in width with a density of 1.38 g cm3.  Concentrations of microplastics in the initial wind tunnel bed ranged from 40-1040 mg kg-1 and the wind tunnel was used to determine the wind speeds at which intermittent and continuous saltation occurred using 0.25 m s-1 increments.  Microplastics were entrained for all experiments regardless of the type of microplastic or substrate but the threshold for entrainment was higher for soils (>10.8 m s-1) than for the sand bed (>6.9 m s-1).  The lowest enrichment ratios (ER) for microplastics were associated with the entrainment of beads from the soil bed (ER = 0.5-7) whilst the highest ERs were found for fibres entrained from the soil bed (ER 100 - >1000).  Overall fibres were more likely to be entrained by wind than beads.  The data will subsequently be used to explore the microplastic concentrations and emissions at source required to account for reported microplastic deposition at sink locations.
Neoglacial Ice Advance and Sediment Provenance Changes in Southwest Greenland and its Marginal Seas Traced by Radiogenic Isotopes
Authors: Madaj Lina , Hillaire-Marcel Claude , Lucassen Friedrich , Kasemann Simone
Published: March 2020

Marine sediments from the West Greenland margin represent high-resolution archives of Holocene climate history, past ice sheet dynamics, changes in meltwater discharge and coastal current intensities. We investigate potential changes of sediment provenances using strontium (Sr) and neodymium (Nd) radiogenic isotopes as tracers for the origin and pathways of the silicate detrital fraction in marine sediments. Meltwater discharge and coastal currents are the most important transport pathways for detrital sediments into (northeast) Labrador Sea, which is an important pathway for freshwater from the Arctic Ocean and meltwater from the Greenland Ice Sheet to enter the North Atlantic, where deep water formation takes place. Variations in freshwater supply into Labrador Sea may influence deep water formation and therefore further circulation and climate patterns on a global scale.

The marine sediment record collected in Nuuk Trough, southwest Greenland, displays uniform isotopic compositions throughout most of the Holocene, indicating well mixed detrital material from local sources through meltwater discharge and distal sources transported via the West Greenland Current. From around 4 ka BP to present the composition of Nd isotopes reveals a steep (εNd: -29 to -35) and the Sr isotope composition a slight (87Sr/86Sr: 0.723 to 0.728) but pronounced shift. This time interval coincides with the transition into the Neoglacial time period [1], which is characterized by a significant drop in atmospheric temperatures [2], and the onset of the modern Labrador Sea circulation pattern (e.g. [3]). We suggest that the shift in Nd and Sr isotopes indicates a change towards less distal and more local sediment sources, possibly caused by enhanced erosion of the local bedrock during Neoglacial ice advance [4], along with a decrease in meltwater discharge [5] and coastal current strength, leading to a sediment delivery shift.

[1] Funder & Fredskild (1989) Quaternary geology of Canada and Greenland, 775–783. [2] Seidenkrantz et al. (2007) The Holocene 17, 387-401. [3] Fagel et al. (2004) Paleoceanography 19, PA3002. [4] Funder et al. (2011) Developments in Quaternary Sciences 15, 699-713, (and references therein). [5] Møller et al. (2006) The Holocene 16, 685-695.
How are the characteristics of Nature-based solutions clustered in European cities?
Authors: Cooper Clair
Published: March 2020

An increased awareness of the way in which urbanisation, climate change, a reduction in the quality, quantity of and access to green space and natural infrastructure (such as blue spaces) all interact to threaten health and well-being of urban populations (Nesshover, et al, 2017; Kabisch & van de Bosch, 2017) has led to the emergence of a new conceptual framework, Nature-based Solutions. Through the management and use of nature, this concept aims to co-produce ecosystems services that not only allow cities to mitigate and adapt against the effects of climate change and increased urbanisation, but also reduce the public health risks associated with these challenges(WHO, 2016, 2017; Hartig at el. 2014; Kabisch et al. 2017), stimulate economies to improve inequality in cities (Nesshover, et al, 2017) and improve the quality of urban life (Mitchel & Popham, 2008; Mitchell et al. 2015). Using data from the Urban Nature Atlas, a database of a 1000 nature-based solutions from across a 100 European cities, this paper examines how the differing characteristics of these solutions (such as their ecological domains, ecosystems services, forms of governance, innovation, etc) are clustered and how the characteristics of these clusters relate to different social, economic and health factors that influence quality of life in our cities.
Global-scale teleconnections of extreme rainfall revealed by complex networks
Authors: Boers Niklas , Goswami Bedartha , Rheinwalt Aljoscha , Bookhagen Bodo , Hoskins Brian , Kurths Jürgen
Published: March 2020

Extreme rainfall events are often coupled across long spatial distances due to atmospheric teleconnections. Revealing such linkages is important for our understanding of extreme events and related atmospheric circulation patterns, but also for enhancing the forecast skill of such events [1]. Here, we present recent results [2] on how complex networks can be employed to discover extreme rainfall teleconnections from high-resolution satellite data. Our method allows to quantitatively distinguish regional weather systems from global-scale teleconnections coupling the individual weather systems. Several lines of evidence suggest that the most relevant mechanisms for global-scale teleconnections of extreme rainfall events are related to atmospheric Rossby waves. We exemplify our approach with a focus on extreme rainfall events in the mountain regions of South-Central Asia (including Northern Pakistan and India), and show that they are statistically significantly coupled to preceding events in Europe as well as succeeding events in eastern China. An analysis of the corresponding atmospheric circulation patterns shows that a previously revealed, quasi-stationary Rossby wave termed the ‘silk road pattern’ [3] is responsible for this instance of long-range coupling between extreme rainfall events. Overall, our findings give new insights into the connections between atmospheric Rossby waves and extreme rainfall events, and thus into the potential predictability of related natural hazards. Moreover, they give promising clues in how to constrain state-of-the-art climate models with respect to their simulation of extreme rainfall.

 

[1] B. Hoskins: The potential for skill across the range of the seamless weather-climate prediction problem: A stimulus for our science, QJRMS 2013

[2] N. Boers, B. Goswami, A. Rheinwalt, B. Bookhagen, B. Hoskins, J. Kurths: Complex networks reveal global pattern of extreme-rainfall teleconnections, Nature 2019

[3] T. Enomoto, B. Hoskins, Y. Matsuda: The formation mechanism of the Bonin high in August, QJRMS 2003
Environmental survey and trial excavation at prehistoric settlement site in Neyshabur Plain, Northeastern Iran
Authors: Zhang Juzhong , Cui Qilong , Luo Wuhong , Yang Yuzhang , Garazhian Omran
Published: March 2020

 Razavi Khorasan Province in the northeast of Iran, located at the Crossroads of Eurasia, was an important point of the middle part of the Silk Road. Neyshabur Plain is situated an important transporting hub of the major thoroughfare of Eurasia. A large number of sites are distributed in the river valleys and the alluvial fans in front of the mountains. Archaeological survey was carried out in Neyshabur Plain, and more than 10 sites were discovered, which are in form of mounds of earth, named as Tape. Seen from the cultural relics on the surface, these sites were occupied by successive cultural sequences, mainly ranging from Neolithic, Chalcolithic, Bronze to Iron Age. This appearance indicates that the climate and environment in the past was better than now. Today, the region is characterized by dry climate, and poor land resources. The land is dominated by Gobi Desert, and the wide vegetation is dominated by Camel thorn (Alhagi sparsifolia). Only in which Karez irrigation system exists, can wheat (Triticum aestivum), barley (Hordeum vulgare) and saffron (Crocus sativus) be cultivated, while a few orchard is present in some river valley areas.

    Tape Borj, which is the largest prehistoric settlement site in the east part of Neyshabur plain, Razavi Khorasan Province, NE Iran, covers an area of 13.5 ha. A total area of 110 m2 was excavated in the north and northwest part of the site, and some geological survey were also conducted around the site in 2019. A total of 14 ash pits, 4 houses, 6 ovens, and one well were unearthed during the excavation. According to the AMS dates and material culture, the cultural deposits can be divided into two phases, including Chalcolithic Age during 6500 BP and 6000 BP and early Bronze Age during 5500 BP and 5000 BP. Some wheat, barley, oats (Avena sativa), and seeds of Celtis sinensis, as well as a large number of animal bones, which are dominated by sheep and goats were discovered. The results can basically reflect the economic structure and subsistence strategy of prehistoric ancestors. Geological survey indicates that two paleo river course ever went through the east and west sides of the site during the prehistoric period. In addition, some samples were systematically collected for pollen and phytolith analysis, in order to understand the paleoenvorinment and the utilization of plant resources by the ancient people at the site from the Chalcolithic to the Bronze Age. Our work can provide some precious material data for studying the evolution of the paleoenvrionment and development of agriculture and animal husbandry in this region.
The GGOS Bureau of Products and Standards
Authors: Angermann Detlef , Gruber Thomas , Gerstl Michael , Hugentobler Urs , Sanchez Laura , Heinkelmann Robert , Steigenberger Peter
Published: March 2020

The Bureau of Products and Standards (BPS) supports GGOS in its goal to obtain consistent products describing the geometry, rotation and gravity field of the Earth. A key objective of the BPS is to keep track of adopted geodetic standards and conventions across all IAG components as a fundamental basis for the generation of consistent geometric and gravimetric products. This poster gives an overview about the organizational structure, the objectives and activities of the BPS. In its present structure, the two Committees “Earth System Modeling” and “Essential Geodetic Variables” as well as the newly established Working Group “Towards a consistent set of parameters for the definition of a new GRS” are associated to the BPS. Recently the updated 2nd version of the BPS inventory on standards and conventions used for the generation of IAG products has been compiled. Other activities of the Bureau include the integration of geometric and gravimetric observations towards the development of integrated products (e.g., GGRF, IHRF, atmosphere products) in cooperation with the IAG Services and the GGOS Focus Areas, the contribution to the re-writing of the IERS Conventions as Chapter Expert for Chapter 1 “General definitions and numerical standards”, the interaction with external stakeholders regarding standards and conventions (e.g., ISO, IAU, BIPM, CODATA) as well as contributions to the Working Group “Data Sharing and Development of Geodetic Standards” within the UN GGIM Subcommittee on Geodesy.