bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequentist and Bayesian extreme value analysis on the wildfire events in Greece
Authors: Koutsias Nikos , Coutelieris Frank A.
Published: March 2020

A statistical analysis on the wildfire events, that have taken place in Greece during the period 1985-2007, for the assessment of the extremes has been performed. The total burned area of each fire was considered here as a key variable to express the significance of a given event. The data have been analyzed through the extreme value theory, which has been in general proved a powerful tool for the accurate assessment of the return period of extreme events. Both frequentist and Bayesian approaches have been used for comparison and evaluation purposes. Precisely, the Generalized Extreme Value (GEV) distribution along with Peaks over Threshold (POT) have been compared with the Bayesian Extreme Value modelling. Furthermore, the correlation of the burned area with the potential extreme values for other key parameters (e.g. wind, temperature, humidity, etc.) has been also investigated.
Internal variability of the Arctic Oscillation and its projections
Authors: Cherchi Annalisa , Oliveri Paolo , van Delden Aarnout
Published: March 2020

The Arctic Oscillation (AO) is one of the main modes of variability of the Northern Hemisphere winter, also referred as Northern Annular Mode (NAM). The positive phase of the AO is characterized by warming/cooling over Northern Eurasia and the United States and cooling over Canada, especially over eastern Canada. Its positive phase is also characterized by very dry conditions over the Mediterranean and wet conditions over Northern Europe. A positive trend of the AO is observed for the period 1951-2011 and it is captured in CMIP5 models only when GHG-only forcing are included. In CMIP5 models the change expected is mostly mitigated by the effects of the aerosols. When considering AR5 scenarios, the AO is projected to become more positive in the future, though with a large spread among the models.

Overall the spread in the representation of the AO variability and trend is large also in experiments with present-day conditions, likely associated with the large internal variability. Unique tools to identify and measure the role of the internal variability in the model representation of the large-scale modes of variability are large ensembles where multiple members are built with different initial conditions.

Here we use the NCAR Community Model Large Ensemble (CESM-LE) composing the historical period (1920-2005) to the future (2006-2100) in a RCP8.5 scenario to measure the role of the internal variability in shaping AO variability and changes. Potential predictability of the AO index is quantified in the historical and future periods, evidencing how the members spread remain large without specific trends in these characteristics. Preliminary results indicate that the internal variability has large influence on the AO changes and related implications for the Northern Hemisphere climate.
Marine Litter Drift Monitoring (Forecast and Hindcast) in the Channel and the North Atlantic
Authors: Vallette Anne , Coulibaly Fatimatou , Emsley Stephen
Published: March 2020

Meteorological events, such as storms and/or gale force winds, act as triggers to influx of macro litter into the hydrological cycle via run off from land into rivers. These rivers discharge into the sea and the marine litter is then transported through the region by currents and wind either becoming entrained in the sea, possibly sinking and/or disintegrating into micro marine litter or ending up being stranded at the coast then washed back ashore or flown on to the land. Thanks to a Copernicus Marine Environment Monitoring Service (CMEMS) grant, ARGANS Ltd has developed a web-based service, called Litter-TEP, that aims to track marine litter from the source. It uses a parametric model of riverine macro litter discharge, to seed drift models of the NE Atlantic Shelf Region (OSPAR II/III), providing to end-users a 5-day running forecast of macro-litter density in the sea, potential beach stranding at the coast and, inversely, where a beach litter event is identified to provide the likelihood of where the litter entered the sea. In order to determine drift trajectories, we use ocean current, wave and wind forecasts from Copernicus Marine Service high quality analysis and forecast products for the European North West Shelf seas. The main issues which have been identified, and for which we perform additional R&D, are the following: a) source’s modelling and estimation of volume of litter introduced to the sea, b) litter’s types for which the drift model should be adapted, and c) the spatial resolution of models in the littoral area (nearshore) vs. offshore. In fact, for the beaching & refloating models, we need of a bathymetry at the scale of 1/3000 and a coastal cartography at 1/1000 to obtain the beach profile, then calculate the runoff on the beach, the rip currents, etc. The next enhancement, driven by users’ requirements, is to improve the land discharge model vide collection of litter seeings with citizen crowdsourcing apps, and records of beach litter surveys, and beach cleaning campaigns. Another improvement, in the mid-term, targets the discharge models, using refined hydrologic schemes for the watersheds, and better estimates of habitats (rural, urban, industrial, …).  ARGANS Ltd service is the next-generation tool for planning beach cleaning and helping local authorities to track back the trash to their sources, leading the fight against litter pollution and for improvement of the river water quality. 
Well integrity evaluation using integrated geophysical well loggings
Authors: Shin Jehyun , Hwang Seho , Kim Geehyun , Kim Yongcheol
Published: March 2020

Well cementing operation is one important factors of well completion as it provides structural support of the casing and hydraulic sealing preventing casing corrosion and groundwater contamination. A wide array of approaches have been developed and applied for leakage detection, including pressure monitoring, radioactive tracer survey, and geophysical surveys. In this work, geophysical well logging methods were adapted to the assessment of well construction and integrity. Various wireline tools yielded physical properties in each borehole environment before and after the casing installation. Several of sonic, nuclear, and mechanical methods focused on valid information to evaluate casing integrity specially after curing concrete for 28 days. Using radioactive logs such as gamma-gamma and neutron logs, we particularly tried to characterize the annular space behind casing, and these well integrity evaluations with cement bond logs corroborated the reliability of the results. Additionally, we reexamined the cement-to-casing bonding condition on the effect of perforation damage. Borehole-based analysis could contribute efficiently to in situ condition evaluation of cementing in which uncontrolled releases of fluid or gas occur.
Impact of Dry Intrusions on the Marine Boundary Layer
Authors: Ilotoviz Eyal , Raveh-Rubin Shira , Ghate Virendra
Published: March 2020

Intrusions of dry air from the upper troposphere were recently suggested to reach the boundary layer and cause its significant deepening. Dry intrusions (DIs) are synoptic-scale slantwise descending airstreams from the midlatitude upper tropospheric jet towards the boundary layer at lower latitudes, thus acting as a circulation type potentially key for understanding boundary-layer cloud occurrence and regime transition. DIs occur mainly during winter over the mid-latitude oceanic storm track regions behind cold fronts trailing from cyclones. These regions are also home to marine boundary clouds that are an important component of the Earth’s radiation budget as they reflect much higher radiation back to the space compared to the ocean surface thereby cooling the Earth’s surface. Although subsidence is generally an inherent feature of the subtropical marine boundary layer, it is unclear how the marine boundary layer reacts to the transient, dynamically distinct DI, differently from the nominal subtropical subsidence resulting from the descending branch of Hadley circulation.

In this study we use the observations made at the Atmospheric Radiation Measurement (ARM) Eastern North Atlantic (ENA) site (39N, 28W) to characterize the impact of dry intrusions on Marine Boundary Layer (MBL) characteristics such as surface fluxes, thermodynamic stabilities and winds. Our analyses are based on measurements from the campaign: radiosondes, surface station data, polarimetric radar, lidar, radar wind profiler, ceilometer among others. Using all identified DI trajectories during the winters of 2016-2018 based on European Center for Medium-range Weather Forecasts (ECMWF) ERA Interim reanalysis data, we distinguish DI days from those before and following DIs, as well as periods with no DIs at all (with and without the occurrence of cold fronts for comparison). We find that during DI events the well-mixed MBL deepens and its vertical structure changes dramatically. Namely, the lower troposphere cools and dries substantially, inducing strong surface sensible and latent heat fluxes, while a strong inversion builds up at the MBL top, all affecting cloud occurrence. Finally, we used the numerical weather prediction (NWP) model COSMO at 2.2 km horizontal resolution to understand the detailed flows and structure in the MBL during DI events.
Towards Real-Time Double-Difference Hypocenter Relocation of Natural and Induced Seismicity
Authors: Scarabello Luca , Diehl Tobias , Kästli Philipp , Clinton John , Wiemer Stefan
Published: March 2020

In order to assess the fault-geometry and the spatio-temporal evolution of natural and induced seismicity, high-precision (relative) micro-seismic hypocenter locations are key information. From such precise relative hypocenter locations, we can infer e.g. the spatial extent during a seismic sequence, the seismogenic volume affected by stimulation procedures as well as geometries (orientation, segmentation) of potentially activated faults. Additionally, in the case of induced seismicity, the spatio-temporal evolution of seismicity (e.g. migration velocities of seismicity, r-t-diagrams) can be indicative for fluid-flow processes and provides first-order estimates of hydraulic properties of the reservoir as well as on the existence of possible hydraulic connections. Information on spatial extent, geometries and the spatio-temporal evolution of seismogenic structures can help to improve the seismic hazard assessment of natural and induced seismicity in real-time or near-real-time.

However, to make prompt use of information provided by such high-precision hypocenter locations requires relative relocations computed in near-real-time. This can be rather challenging, especially at the beginning of a seismic sequence, when only little or no background seismicity is available for relative relocation. In addition, an automated relative relocation process requires differential times derived from precise and reliable (absolute) automatic picks as well as from waveform cross-correlation.

In this work, we present our strategy towards a near-real-time relative relocation procedure. The procedure follows the methodology described by Waldhauser 2009 (BSSA; doi:10.1785/0120080294) and combines differential times derived from automatic as well as manual picks with waveform cross-correlations measurements. Differential times of new events are inverted for relative locations with respect to a background reference catalog using the double-difference algorithm. We present results derived by a python-based prototype applied to natural and induced earthquake sequences. In addition, the prototype is fully implemented in a new SeisComP3 (SC3) module “scrtdd”, which allows the application in a full real-time environment, using detections and locations from various existing SC3 modules (“scautoloc”, “scanloc”, “screloc”) as input for relative relocation. We outline our implementation strategy, and compare SC3 results with results derived by our software for natural and induced earthquakes monitored be dense near-fault monitoring networks in the Valais (SW Switzerland), St. Gallen (Switzerland) and the Hengill Geothermal Field (SW Iceland).
BioLink: Linking belowground biodiversity and ecosystem function in European forests
Authors: Godbold Douglas , Bakker Mark , Brunner Ivanno , Lukac Martin
Published: March 2020

Biodiversity of ecosystems is an important driver for the supply of ecosystem services to people. Soils often have a larger biodiversity per unit surface area than what can be observed aboveground. Here, we present what is to our knowledge, the most extensive literature-based key-word assessment of the existing information about the relationships between belowground biodiversity and ecosystem services in European forests. The belowground diversity of plant roots, fungi, prokaryota, soil fauna, and protists was evaluated in relation to the supply of Provisioning, Regulating, Cultural, and Supporting Services. The soil biota were divided into 14 subgroups and the ecosystem services into 37 separate services. Out of the 518 possible combinations of biotic groups and ecosystem services, no published study was found for 374 combinations (72%). Of the remaining 144 combinations (28%) where relationships were found, the large majority (87%) showed a positive relationship between biodiversity of a belowground biotic group and an associated ecosystem service. We concluded that (1) soil biodiversity is generally positively related to ecosystem services in European forests; (2) the links between soil biodiversity and Cultural or Supporting services are better documented than those relating to Provisioning and Regulating services; (3) there is a huge knowledge gap for most possible combinations of soil biota and ecosystem services regarding how a more biodiverse soil biota is associated with a given ecosystem service. Given the drastically increasing societal demand for knowledge of the role of biodiversity in the functioning of ecosystems and the supply of ecosystem services, we strongly encourage the scientific community to conduct well-designed studies incorporating the belowground diversity and the functions and services associated with this diversity.
Fate of atmospheric nitrogen depositions in two Italian temperate mountain forests assessed by isotopic analysis
Authors: Da Ros Luca , Ventura Maurizio , Rodeghiero Mirco , Gianelle Damiano , Tonon Giustino
Published: March 2020

Abstract. Forests ability to store carbon is strongly connected with the amount of nitrogen (N) that forest ecosystems can retain; N is indeed considered the most limiting nutrient for terrestrial ecosystem's net primary productivity. Since the industrial revolution, human activities have more than doubled the rate of N input into the nitrogen cycle and this could alleviate N limitation thus stimulating plant growth. However, it has been suggested that when N availability exceeds biotic demand and abiotic sinks, additional N can trigger a negative cascade effect: nutrient imbalance, reduced productivity, increased losses of N, eutrophication and acidification of soil and water, leading toward forest decline and net greenhouse gases emissions. The consequences of increased N deposition on forest depend in large share on the fate of N in the ecosystem, which can be simulated and quantified by a fertilization at a known isotopic signature. Nevertheless, most of the tracer experiments performed so far added the fertilizer directly to the forest floor, neglecting the potential role of N uptake by the forest canopy. In the Italian Alps, we are conducting an experiment where both types of N additions (above and below the canopy layer) are performed in two different forest stands, to understand if canopy fertilization better simulates ecological consequences of increased atmospheric N deposition. These field-scale manipulation experiments are willing to test two different hypotheses: i) the N uptake by trees in the above-canopy N addition experimental sites is higher than under-canopy N addition ii) forest growth rate varies with the type of treatment. To describe the fate of the applied N, stable isotope techniques have been adopted: the forest sites, fertilized with NH4NO3 at a known isotopic signature, are sampled for all the ecosystem components (plant, soil and water) periodically to determine the total N content and its isotopic signature. The δ15N values permit to calculate the recovery of N-fertilizer in tree tissues, soil and leaching-water, allowing us to understand how N allocation varies under these two fertilization strategies and how this affects C sequestration potential. Results regarding the short-term effects over the first 6 years of data collection will be presented.
A global Biogeochemical Argo pilot array: Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) profiling floats and results
Authors: Talley Lynne , Johnson Kenneth , Riser Stephen , Sarmiento Jorge , Russell Joellen , Boss Emmanuel , Mazloff Matthew , Wijffels Susan
Published: March 2020

The ocean provides critical services to life on the planet, absorbing 93% of the heat from anthropogenic warming and a quarter of human carbon dioxide (CO2) emissions each year. However, rising ocean temperatures and CO2 levels also change the marine environment: pH and oxygen levels fall, ocean currents change, and nutrient fluxes and concentrations are shifting, all with large effects on ecosystems and the cycles of oxygen, nitrogen, and carbon throughout the ocean and atmosphere. Observing these biogeochemical (BGC) processes across remote ocean areas with seasonal to interannual resolution has been impractical due to the prohibitive costs associated with ship observations. Yet such observations are essential to understand the natural and perturbed systems.

Profiling floats, proven in the Argo program, with BGC sensors (oxygen, nitrate, pH, bio-optical) provide a transformative solution to this need.  BGC profiling floats are capable of observing chemical and biological properties from 2000 m depth to the surface every 10 days for many years. Based on various OSSE and sampling approaches, global coverage can be achieved with 1000 BGC floats contributing to the core T/S Argo array of about 4000.

The U.S. Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) program serves as a major basin-scale pilot for such a global array. Its 141 operating BGC floats, building towards an ultimate 200 floats, demonstrate that the major challenges associated with operating a large-scale, robotic network have been overcome, and that there is a substantial user base for the data. Data have been publicly available in near real-time since the start of SOCCOM. Robust protocols for QC, calibration and validation of BGC float data have been developed, based on GLODAPv2 climatologies and relationships between the observed float variables. Data are being incorporated in BGC state estimation and are being used for comparison/validation of ocean models used for climate. Initial SOCCOM results are already transforming understanding of Southern Ocean biogeochemistry. Annual cycles of air-sea carbon flux are revealing major surprises, including strong outgassing within the Antarctic Circumpolar Current.  Annual net community production in all major regimes of the Southern Ocean has been quantified.  The broad-scale float profiling has validated NASA's satellite algorithms for POC and chlorophyll in the Southern Ocean. As the international community moves forward towards sustained BGC-Argo deployments, SOCCOM can provide its experience in sensors, floats, deployments, calibration, and data management. 
Methane consumption by proteobacterial methanotrophs in boreal spruce phyllosphere activated with methane
Authors: Siljanen Henri , Laihonen Antti , Aalto Sanni , Martikainen Inga , Lamprecht Richard , Biasi Christina , Tiirola Marja
Published: March 2020

Current knowledge on methane (CH4) sinks is limited to chemical processes in the atmosphere, and to methanotrophy in forest soils and peatlands. Recent discoveries have indicated that also tree branches, i.e. phyllosphere, may consume atmospheric CH4, thus functioning as a novel CH4 sink. However,  the process is not yet confirmed and the mechanism not resolved.

Here, we confirm that leaves and needles of boreal trees have the capacity to consume CH4 with stable isotope enrichment studies in field and laboratory experiments, and that the consumption is a biological process. With molecular analyses, we confirmed that the activity of needle-associated proteobacterial methanotrophs increased sporadically under CH4 and acetate enrichment. Our results indicate that CH4 consumption can exist in the tree canopy, which is characterized by interspecies variation, spatial patchiness and small but significant microbial activity.

This is a novel symbiotic connection between microbes and plant cells, which can enhance overall carbon sequestration in the boreal forests.
Avalonia, get bent! Paleomagnetism from SW Iberia confirms the Greater Cantabrian Orocline
Authors: Leite Mendes Bruno Daniel , Pastor-Galan Daniel , Dekkers Mark J. , Krijgsman Wout
Published: March 2020

The amalgamation of Pangea formed the contorted Variscan-Alleghanian orogen suturing Gondwana and Laurussia during Carboniferous. From all swirls of this orogen, a double curve stands out in Iberia, the coupled Cantabrian Orocline and Central Iberian Curve. The Cantabrian Orocline formed subsequent to Variscan orogeny (ca. 315-295 Ma). The mechanisms of formation for this orocline are disputed being the most prominent:

1) An Avalonian (Laurussia) indenter at SW Iberia, that would form the Cantabrian Orocline in a sinistral transpressive orogenic phase.

2) A change in the stress field that buckled the orogen. This change in stress would be potentially far-field and linked to subduction of the Paleo-tethys and/or diachronous collision in the Variscan belt.

In contrast, the geometry and kinematics of the Central Iberian curve are largely unknown. Whereas some authors defend both curvatures are genetically linked, others support they are distinct and formed at different times. Such uncertainty adds an extra layer of complexity into our understanding of the final stages of Pangea amalgamation.

We have performed a paleomagnetic analysis of several tectonostratigraphic units in SW Iberiat to solve the late Carboniferous Variscan kinematics. Our results show differential counterclockwise rotations, ranging from 20˚  and up to 70˚ at late Carboniferous. These results are coincident with the kinematics expected in the southern limb of the Cantabrian Orocline and discard a concomitant formation of both Cantabrian and Central Iberian curvature. The Avalonian portion of Laurussia rotated with the Cantabrian Orocline at both limbs: the northern one (Ireland, Pastor-Galán et al., 2015) and the southern one (South Portugese Zone, this study). The coherent rotation of Avalonia confirms the Greater Cantabrian Orocline hypothesis and discards the Avalonian indenter as a mechanism of formation for the Cantabrian Orocline. The Greater Cantabrian Orocline extended beyond the Rheic Ocean suture affecting both Laurussia and Gondwana margins and probably formed by a late Carboniferous change in the stress field, due to a still unidentified cause.
Improved Inversion of Monthly Ammonia Emissions in China Based on the Chinese Ammonia Monitoring Network and Ensemble Kalman Filter
Authors: Tang Xiao , Kong Lei , Zhu Jiang , Wang Zifa , Pan Yuepeng , Wu Huangjian , Wu Lin , Wu Qizhong , He Yuexin , Tian Shili , Xie Yuzhu , Liu Zirui , Sui Wenxuan , Han Lina , Carmichael Greg
Published: March 2020

Ammonia (NH3) emission inventories are an essential input in chemical transport models and are helpful for policy-makers to refine mitigation strategies. However, current estimates of Chinese NH3 emissions still have large uncertainties. In this study, an improved inversion estimation of NH3 emissions in China has been made using an ensemble Kalman filter and the Nested Air Quality Prediction Modeling System. By first assimilating the surface NH3 observations from the Ammonia Monitoring Network in China at a high resolution of 15 km, our inversion results have provided new insights into the spatial and temporal patterns of Chinese NH3 emissions. More enhanced NH3 emission hotspots, likely associated with industrial or agricultural sources, were captured in northwest China, where the a posteriori NH3 emissions were more than twice the a priori emissions. Monthly variations of NH3 emissions were optimized in different regions of China and exhibited a more distinct seasonality, with the emissions in summer being twice those in winter. The inversion results were well-validated by several independent datasets that traced gaseous NH3 and related atmospheric processes. These findings highlighted that the improved inversion estimation can be used to advance our understanding of NH3 emissions in China and their environmental impacts.
A review of Aleutian Low variability for the last 7,500 years using pan-Pacific delta 18O records
Authors: Nagashima Kana , Addison Jason , Harada Naomi
Published: March 2020

   The North Pacific Ocean is the largest geographic feature in the Northern Hemisphere and its interactions with the overlying atmosphere drives critical components of the global climate system. The Aleutian Low (AL), the semi-permanent atmospheric low-pressure system centered near the Aleutian Islands, is dynamically linked to environmental change in the North Pacific and surrounding continental areas. However, the multi-centennial and longer time-scale history of the AL during the Holocene is poorly understood.

   In this study, AL variability since 7.5 ka was examined by applying principal component analysis (PCA) to published δ18O data of sedimentary calcite, peat, and speleothem deposits (n = 7) from western North America. Extracted Principal Component 1 (PC1) is characterized by multi-centennial to millennial-scale oscillations, with a spatial loading pattern that suggests PC1 reflects intensification and westward shifts of the AL during ca. 7.3–7.1, 6.3–5.2, 3.6–3.3, 2.9–2.7, 2.6–2.1, 1.8–1.2 and 0.5–0.3 ka. The timing of these shifts are coeval to periods characterized by large meanderings of the Westerly Jet (WJ) Stream over East Asia and solar activity minima, which together suggest that AL variability is related to declines in solar irradiance through its interactions with the WJ. In contrast, PC2 represents a dramatic change between the middle and late Holocene, and appears to reflect long-term intensified AL conditions related to orbitally-driven El Niño–Southern Oscillation intensification between the middle to late Holocene at ~4.5 ka. These findings are critically important for understanding background natural climate variability during the Holocene.
Geomagnetic field variations due to Solar and Lunar tides in the Brazilian Sector
Authors: Tsali-Brown Vera Yesutor , Fagundes Paulo Roberto , Paulino Ana Roberta , Pillat Valdir Gil , Bolzam Maurício José Alves
Published: March 2020

Abstract

Geomagnetic field variations in 2018 due to solar and lunar tides in the Brazilian sector were studied using data provided by magnetometers installed at São José dos Campos (23.21oS, 0345.97oW; Dip latitude 20.9oS), Eusébio, Ceará (3.89° S, 38.46° W) and São Luís, Maranhão (2.53° S, 44.30° W). Variations associated with these tides were identified using the horizontal component of the geomagnetic field, H(nT). Least square fit method was employed in determining the monthly amplitudes and phases of the diurnal, semidiurnal and ter-diurnal solar tides. The monthly amplitudes and phases of the lunar tide were then calculated using the residual measurements (obtained after subtracting the solar tidal components from each day), converting the solar local time to lunar time and subjecting the residuals to harmonic analysis. The maximum solar tide amplitude recorded was 23.96nT(diurnal) in March, at Eusébio whereas the minimum amplitude was 0.45nT(terdiurnal) recorded in December at São José dos Campos. The lunar tide recorded a maximum amplitude of 4.33nT(semidiurnal) in February, at São Luís and a minimum amplitude of 0.13nT(diurnal) in August, at Eusébio.

 

 

Keywords: Solar tides, Lunar tides, Geomagnetic field, Magnetometer.

 
The ROBOMINERS “advanced mineralogical segment”: an in-stream, in slurry analytical module designed for robotic ore exploration and production
Authors: Burlet Christian , Stasi Giorgia , Vanbrabant Yves
Published: March 2020

The Horizon 2020 ROBOMINERS project (Grant No. 820971), is developing concepts and prototypes for a bio-inspired, modular and reconfigurable robot-miner for small and difficult to access deposits. This covers both underexplored or currently flooded mines not accessible anymore for conventional mining techniques; or places that have formerly been explored, but whose exploitation was considered non-economic due to the small size of the mineralization or its accessibility.

As part of the sensors payload of the miner, a modular segment of the robot will contain sophisticated geochemical/mineralogical sensors capable of characterising the slurry produced by the drilling process in real-time and interpreting the data as mining diagnostics and navigation parameters for the progression of the miner. This segment will perform in-stream analyses of the drilling slurry using sampling inlet-outlet ports. The sensing techniques currently considered for this segment are LIBS (Laser-induced breakdown spectroscopy), EDXRF (Energy dispersive X-Ray fluorescence), LINF (Laser-induced native fluorescence), Terahertz imagery and time-resolved Raman.

This study presents the first laboratory-scale prototype of this segment, and tests on slurry analogues (bentonite/baryte/salt mixtures of sphalerite ore) with a high-repetition LIBS analyser (1064nm 20 KHz laser, 200-850nm spectrometer, co-axial light collection). As a proof of concept for high-pressure operation, the plasma sparks are created inside the opaque liquid medium using a synchronized argon gas dispenser in front of the laser window. This innovative setup was successfully tested in this study under a pressure range of 1 to 10 bar and a superficial gas velocity range of 50 to 100 mm/s. The next steps in the study is to increase the slurry pressure to simulate deep borehole operation and couple LIBS with a complementary analyser like EDXRF.
Exploring geophysical properties of Sn-Cu-Pb-Zn deposits at depth using ROBOMINERS’ mid-perception capability.
Authors: Stasi Giorgia , Burlet Christian , Nguyen Frederic , Vanbrabant Yves
Published: March 2020

The Horizon 2020 ROBOMINERS project (Grant No. 820971) is developing a modular robot miner prototype following a bio-inspired design, capable of operating, navigating and performing selective mining in a flooded underground environment.

The project has been set up with the long-term strategic objective to facilitate EU access to mineral raw materials – including those that are considered as strategic or critical for the energy transition - from domestic resources and decreasing thus the European import dependency. The use of the robot miner will especially be relevant for mineral deposits that are small or difficult to access.

Conventional DC resistivity and IP methods for geophysical exploration are well reported in the literature, however, in the framework of ROBOMINERS we wants to develop a new approach for DC resistivity and IP that use the deposit itself as a probe for the diffusion of the signal.

Ideally the electrode will be positioned at the end of the robot legs (in contact with the terrain) and the source on the drilling head. This set up will allow to move the source and electrode in preferential position in order to cover the biggest surface possible, and to maximize resistivity measurements avoiding the lack of resolution due to the positioning of electrodes on grounds surface or distant borehole.

In addition to resistivity measurement we are considering an additional technique, namely the Terahertz spectroscopy. The concept for the THz scanning spectroscopy is to use the body of the robot to arrange at 360° the THz detectors and install on the robot’s front the THz source (positioned on a mobile arm or on the drilling head). This technique will allow to scan the mine’s wall and produce a first model of the deposit section. This model will then help for the positioning of the DC/IP source. THz spectroscopy can be applied for the screening of the wall in case it is covered in drilling mud, where regular multispectral camera might not work. As this technique is highly affected by the presence of water is not yet defined its precise field of applicability that will need to be outlined within the project framework.

For our scope we are going to consider (narrow-) vein type and stratiform deposits; those kinds of deposits that could have formerly been explored but their exploitation was considered as uneconomic due to the small size of the deposits or their difficulty of access. More specifically we are going to investigate and review the geophysical properties of tin-lead-zinc wolframite vein type deposit for DC resistivity and IP technique and Terahertz spectroscopy.

2.11.0.0
Research on Improvement of Rural area Population Spatial Distribution Model Based on Random Forests
Authors: Dong Chun
Published: March 2020

Since the founding of New China, especially since the reform and opening up, China has experienced the fastest economic development and the most profound population migration in history. The large-scale migration of China's rural population and labor force is particularly evident. China's rural population accounts for 40.42% in 2019. China's rural population is large, and urban-rural and regional differences are also large. Due to the current data and information limitations and the characteristics of China's national conditions, there are very few related studies on China's overall rural population.

Fine-scale population distribution data at the fine scale play an essential role in numerous fields, for example urban planning and management, and disaster assessment and developing population differentiation policies. The rapid technological development of remote sensing (RS) and geographical information system (GIS) in recent decades has benefited many fine resolution population spatialization studies. However, most of the existing population spatialization methods have been studied at the regional or urban scale, and few studies have been conducted on the unit population in rural areas. In view of the fact that existing demographic data cannot meet the actual needs of analysis, management and scientific research in terms of spatial precision, a new population distribution estimation method combining nighttime lighting and residential building attributes is proposed in our study. In view of this, studying the spatial distribution of the population in rural areas is used as the purpose of this article. Based on the night light data, natural city boundaries are determined. A rural area delineation method based on Head-to-Tail segmentation classification combined with administrative village verification is proposed, which provides a feasible method for large-scale automatic extraction of rural area boundaries. Coupled with POI (Points of Interest) data, based on elevation, slope, night light images, and land cover, the population spatialization model of the random forest is developed and improved based on the weight of the house properties and light intensity. Finally, a high-precision population distribution dataset is obtained, which is closer to the actual population distribution. The research results show that based on the proposed population spatialization model, street demographic values can be fitted better, and the basis for more accurate population estimation is laid. It provides a reference for data fusion and is of great significance for rural area development planning.
15 years of snow manipulation reveals huge impact on lowland permafrost and vegetation
Authors: Johansson Margareta , Åkerman Jonas , Blume-Werry Gesche , Callaghan Terry V. , Christensen Torben R. , Monteux Sylvain , Dorrepaal Ellen
Published: March 2020

Snow depth increases observed and predicted in the sub-arctic are of critical importance for the dynamics of lowland permafrost and vegetation. Snow acts as an insulator that protects vegetation but may lead to permafrost degradation. In the Abisko area, in northernmost Sweden, there has been an increasing trend in snow depth during the last Century. Downscaled climate scenarios predict an increase in precipitation by 1.5 - 2% per decade for the coming 60 years. The observed changes in snow cover have affected peat mires in this area as thawing of permafrost, increases in active layer thickness and associated vegetation changes have been reported during the last decades. An experimental manipulation was set up at one of these lowland permafrost sites in the Abisko area (68°20’48’’N, 18°58’16’’E) 15 years ago, to simulate projected future increases in winter precipitation and to study their effect on permafrost and vegetation. The snow cover has been more than twice as thick in manipulated plots compared to control plots and it has had a large impact on permafrost and vegetation. It resulted in statistically significant differences in mean winter and minimum ground temperatures between the control and the manipulated plots. Already after three years there was a statistically significant difference between active layer thickness in the manipulated plots compared to the control plots. In 2019, the active layer thickness in the control plots were around 70 cm whereas in the manipulated plots it was 110 cm. The increased active layer thickness has led to surface subsidence due to melting of ground ice in all the manipulated plots. The increased snow thickness has prolonged the duration of the snow cover in spring with up to 22 days. However, this loss in early season photosynthesis was well compensated for by the increased absorption of PAR and higher light use efficiency throughout the whole growing seasons in the manipulated plots. Eriophorum vaginatum is a species that has been especially favored in the manipulated plots. It has increased both in number and in size. Underneath the soil surface, the roots have also been affected. There has been a strong increase in total root length and growth in the active layer, and deep roots has invaded the newly thawed permafrost in the manipulated plots. The increased active layer thickness has also had an effect on the bacterial community composition in the newly thawed areas. According to past, century-long patterns of increasing snow depth and projections of continuing increases, it is very likely that the changes in permafrost and vegetation that have been demonstrated by this experimental treatment will occur in the future under natural conditions.
An Approach for Determining the Geopotential Difference between The Atomic Clocks Ensemble in Space (ACES) and a ground station
Authors: Ashry Mostafa , Shen Wenbin , Sun Xiao
Published: March 2020

According to the general theory of relativity, two clocks placed at two different positions with different geopotential run at different rates. Thus one can determine the geopotential difference between these two points by comparing the running rates of the two clocks. In this paper, we propose, design and describe in detail an approach for determining the geopotential difference between The Atomic Clocks Ensemble in Space (ACES/PHARAO mission) and a ground station based upon a simulation experiment. The correction due to Ionosphere, troposphere and Sagnac effect will be taken into account. Our team is working on a wide range of problems that need to be solved in order to achieve high accuracy in (almost) real-time. In this paper, we will present some key aspects of the measurement, as well as the current status of the software's development. the proposed approach may have prospective applications in geoscience, and especially, based on this approach a unified world height system could be realized with one-centimetre level accuracy in the near future.
Physical and remote access to the European Volcano Research Infrastructures as a strategy to promote the community building: efforts, challenges, and results.
Authors: Spampinato Letizia , Puglisi Giuseppe
Published: March 2020

Indeed, nowadays data sharing via internet is one of the most used approaches to networking scientific communities. However, the opportunity to physically access Research Infrastructures (RIs) and their installations and facilities is potentially the most powerful mean to build up a community. Physically access, in fact, makes the ideal conditions for the RI’s providers and users to work side by side on specific research topics. This is recently the case of the European trans-national access activities promoted in order to allow and push the volcanology community to use either the volcano observatories, to carry out experiments or fieldworks, or laboratories, for exploiting analytical and computational facilities, belonging to the main European volcano research institutions.

The EUROVOLC project has granted the access to 11 RIs for an overall of 45 installations, including single facilities of pools of mobile instrumentation and of laboratories, and remote access to collections of volcanic rocks, of 5 European countries (France, Iceland, Italy, Portugal, and Spain). In the frame of the project, the trans-national access offer has come from 7 partners (IMO, UI, INGV&CNR, CIVISA, IPGP, and CSIC) acting in 7 WPs (13, 14, 16, 16, 17, 18, and 19).

The EUROVOLC work-plan has foreseen two calls, one in 2018 and the other in 2019, allowing users to apply for access the RIs, and the effective physical access in 2019 and 2020, respectively. Each call has been managed according to a stepwise process based on an excellence-driven criterion, in which the roles of the various actors and the schedule have been previously defined.

This contribution aims at presenting the management and coordination efforts related to the trans-national access activities in the frame of EUROVOLC including the preparation and the launch of the 1st call, the process of the selection of the proposals, the feedback from the management of the 1st call, the preparation of the 2nd call, and a critical analysis for improving the management of the 2nd call.
Fate of glyphosate and AMPA in the vadose zone: dissipation, transport and adsorption
Authors: Mencaroni Marta , Dal Ferro Nicola , Cardinali Alessandra , Carretta Laura , Costa Leonardo , Mazzega Ciamp Stefano , Morari Francesco , Salanin Paolo , Zanin Giuseppe
Published: March 2020

Broad contamination of systemic herbicide glyphosate –GLP– (N-(phosphonomethyl) glycine) and its metabolite aminomethylphosphonic acid (AMPA) in soil and water has become one of the main environmental issues worldwide, raising awareness of the potential harmful effects to human health and ecosystems. Physical, chemical, and biological soil properties contribute to the complex interaction between GLP and the environment, that makes any prediction of adsorption, transport, and degradation dynamics still challenging.

Within a wide project –SWAT– that tries to link GLP and AMPA dynamics through the vadose zone with groundwater contamination, the specific goals of this work are: 1. monitoring soil and water contamination of GLP and AMPA in agricultural lands; 2. identifying the driving factors leading to site-specific soil-water contaminant interactions.

Two experimental sites were located in northeastern Italy (Conegliano and Valdobbiadene municipalities) in the winegrowing terroir of the Prosecco wine production, recently included in the UNESCO’s World Heritage List. Each site was equipped with two soil-water monitoring stations (25 m2 each), multi-sensor soil probes (temperature and water content) and suction lysimeters to monitor the full soil profile. Undisturbed soil cores were also collected and later analyzed for hydraulic, physical and chemical properties down to 70 cm. After GLP field contamination on November 2018 (0.188 g m-2), soil and water were systematically sampled from each site, starting immediately after contamination and thereafter at each rain event for 6 months. Adsorption coefficients (Kf) were estimated in laboratory in order to get information about GLP sorption to soil particles at different soil layers along the full soil profile. Site-specific dissipation kinetics (DT50) were also evaluated to better understand its decay rate.

First results revealed that GLP transport was highly site specific and locally affected by preferential flows when intense rainfall events occurred (12 mm h-1 max rainfall intensity): GLP showed strong binding affinity to soil particles in the topsoil layer and it likely bypassed the porous matrix towards the deepest layers, where it was detected as in the surface one. The GLP dissipation dynamic was completed after 6 months of experimentation, whereas AMPA was still detected in the topsoil layer, attesting the full degradation after almost 300 days. Site-specific laboratory and field data will be integrated and further discussed to better understand the fate of glyphosate and AMPA in the vadose zone.
New particle formation events persistently reduce cloud droplets in boundary layer clouds
Authors: Patoulias David , Florou Kalliopi , N. Pandis Spyros , Nenes Athanasios
Published: March 2020

Α considerable fraction of cloud condensation nuclei (CCN) originates from new particle formation (NPF). Because of this, NPF events themselves are thought to also increase CCN and cloud droplet number (CDN) and contribute to climate cooling. High resolution state-of-the-art simulations over Europe however portray a different view: radiatively important stratiform clouds influenced by NPF events experience a systematic and substantial decrease in droplet number during and after nucleation events. The drop in CDN occurs because particles present prior to the NPF experiences slower growth during and after each event (as the condensable material is consumed by the growth of the NPF particles that do not typically activate), leading to fewer CCN at the low supersaturation levels characteristic of stratiform clouds (~0.1%). Convective clouds, however, tend to experience a modest increase in cloud droplet number – consistent with established views on the NPF-cloud link. Our results are corroborated by published observational evidence and all together reshape our conceptual understanding of NPF events on clouds, where droplets in stratiform clouds tend to be reduced (leading to local warming from reductions in cloud albedo) but enhance in convection. Combined, these effects could bear important impacts on cloud structure following NPF events.