bluuebunny/crossref_metadata_2025 huggingface dataset:
The tectonic and volcanic evolution of the Mangatolu Triple Junction
Authors: Mensing Rebecca , Stewart Margaret , Hannington Mark , Baxter Alan , Mertmann Dorothee
Published: March 2020

The Mangatolu Triple Junction (MTJ) is an intraoceanic back-arc spreading center that is host to at least 3 distinct hydrothermal systems. It is located in the NE Lau Basin, which opened due to rollback of the Pacific plate along the Tonga-Kermadec trench. At the MTJ, three spreading centers meet in a ridge-ridge-ridge (RRR)-type triple junction separating the Tonga plate in the east, the Niuafo’ou microplate in the southwest, and an unnamed microplate in the north. The MTJ is directly linked to the formation and evolution of the Northeast Lau microplate mosaic, as plate fragmentation inevitably results in the formation of triple junctions, but it remains unclear whether the spreading centers are the drivers of plate fragmentation or a consequence of stress relocation related to microplate rotation. Detailed investigation of the geology and structural setting of the MTJ therefore provides valuable insight into the development in the northeast Lau Basin. Here we present the first comprehensive 1:200,000 geological map of the MTJ, based on a compilation of marine geophysical data (hydroacoustics, magnetics, and gravity) derived from 7 research cruises that have investigated the region between 2004 and 2018. Analysis of the mapped geological formations at the MTJ shows the importance of relict arc crust originating from the Tofua Arc in the architecture of the triple junction, which includes three stages of back-arc crust development and extensive off-axis volcanism. The spreading centers along each arm of the MTJ exploit pre-existing crustal weaknesses, interpreted to have formed during initial Lau Basin opening. A reconstruction of the basin opening, based on the mapped features and published spreading rates, revealed that initiation of the MTJ commenced approximately 180,000 years ago, consistent with the very recent and ongoing dynamic evolution of the NE Lau Basin and emerging microplate mosaic. Intersecting fabrics indicate sequential evolution of the 3 arms of the triple junction, with extension along the northeast arm dominant in the early history and more recent extension along the southern and western arms. The results of this study contribute to our growing understanding of the tectonic framework of the northeast Lau Basin and the role of triple junctions in microplate formation.
Recovery of metals from mining tailings by eco-friendly hydrometallurgical processes
Authors: Gascó Gabriel , Sánchez Ignacio , Fidalgo José Manuel , Saa Antonio , Paz-Ferreiro Jorge , Méndez Ana
Published: March 2020

Metal´s demand and price are increasing due to the global trend towards urbanisation and industrialisation. Metals and raw materials are crucial to Europe’s society, economy and industry. However, some of them show a high-supply risk due to high dependence of imports, being necessary to find alternative materials or new sources for their recovery. Additionally, the overall global reserves of high-grade ores are close to depletion. In this context, low-grade, complex ores like sulphide minerals and old waste deposits related to past mining activities have received much more attention in recent years as new metal sources. The main objective of the present work is the recovery of metals from mining tailings, mainly post-flotation wastes, by eco-friendly hydrometallurgical processes. The presence of low-grade minerals hinders metal extraction by traditional pyrometallurgical processes. Spanish mining tailings show different compositions depending on their origin. However, complex ores like sulphide minerals (pyrite; sphalerite; chalcopyrite; arsenopyrite and other polymetallic sulphides) are generally present. It is known that metals in the form of complex sulphide precludes their chemical leaching.  For this reason, some carbon materials have been studied during last years as efficient catalysts for the leaching of metals from complex sulphides. The present work will be performed during the project RTI2018-096695-B-C31 (Ministerio de Economía y Competitividad). Different mining taillings will be selected from Spanish mining areas and mix with corresponding carbon catalysts. Leaching experiments will be performed during 96 hours at 60 and 90ºC under continuous agitation. The results obtained in the project will contribute to better understanding of the influence of catalysts in the leaching of metals from mineral sulphides. 
Authors wish to thank Spanish Ministerio de Economía y Competitividad for economic support (RTI2018-096695-B-C31)
Renewed Inflation of Krafla Caldera, Iceland, since 2018: Sensitivity of Ground Deformation to lateral variation in Earth structure and architecture of the magmatic system explored with the Finite Element Method
Authors: Lanzi Chiara , Drouin Vincent , Li Siqi , Sigmundsson Freysteinn , Geirsson Halldor , Hersir Gylfi Pall , Agustsson Kristjan , Hreinsdottir Sigrun , Gudmundsson Asgrimur
Published: March 2020

The Krafla volcanic area in Northern Volcanic Zone of Iceland was characterized by deflation starting in 1989, suggesting a general pressure decrease and/or volume contraction at depth, which then exponentially decayed until having no significant deformation since around 2000.  In summer 2018, the volcano behaviour changed to inflation as observed both by Global Navigation Satellite System (GNSS) geodesy  and Sentinel-1 satellite radar interferometry (InSAR). Inflation since 2018 occurs at a rate of 10-14 mm/yr, centered in the middle of the caldera. No significant change in seismicity has occurred in the area in 2018, but seismic moment release ocurrs at a higher rate since middle 2019. Gravity stations in the area were remeasured in November 2019 for allowing comparison with earlier observations, and for providing reference for later studies. Initial modelling of the geodetic data is carried out assuming that the deformation is caused by a spherical source of pressure in an uniform elastic half-space. The result suggests that the deformation can be broadly explained by a single source of magma inflow at depth around 3.9-7.5 km, with the best-fit value around 4-4.5 km. We also apply the Finite Element Method (FEM) to additionally consider modification of the deformation field caused by Earth’s elastic heterogeneities and the uncertain geometry and  depth of the magma source. A set of FEM models are built with the COMSOL Multiphysics software in a 50x50 km domain where we test three different geometries of the source: a spherical source (radius 1000 km), a prolate ellipsoid,  and an oblate ellipsoid (sill-like) source, at 2.5, 4.0 and 5.5 km of depth. We also build a model to test how the vertical and horizontal displacements may be influenced by different elastic properties (e.g. Young’s modulus; about an order of magnitude different within a caldera boundary) for these sources. The results show that lateral variations in material properites can have a significant influence on ground deformation. Low-value Young’s inside caldera boundaries compared to higher values outside caldera boundaries will in particular influence the vertical displacement: the vertical displacement is about half of of what it is the original modelling.  The ratio of vertical to horizontal displacements will thus also be modified. This can in turn influence the inferred magma source geometry as it depends on the displacement ratios. The outcome of our study will provide better constrain for the elastic properties in Krafla area, and help understand the magma intrusion rate in the area.
Importance of wind variations and intersecting waveguides near Sri Lanka for the intraseasonal sea level variability along the west coast of India
Authors: Suresh Iyyappan , Vialard Jerome , Lengaigne Matthieu , Izumo Takeshi , Pillathu Moolayil Muraleedharan
Published: March 2020

Remote wind forcing plays a strong role in the Northern Indian Ocean, where oceanic anomalies can travel long distances within the coastal waveguide. Previous studies for instance emphasized that remote equatorial forcing is the main driver of the sea level and currents intraseasonal variability along the west coast of India (WCI). Until now, the main pathway for this connection between the equatorial and coastal waveguides was thought to occur in the eastern equatorial Indian Ocean, through coastal Kelvin waves that propagate around the Bay of Bengal rim and then around Sri Lanka to the WCI. Using a linear, continuously stratified ocean model, the present study demonstrates that two other mechanisms in fact dominate. First, the equatorial waveguide also intersects the coastal waveguide at the southern tip of India and Sri Lanka, creating a direct connection between the equator and WCI. Rossby waves reflected from the eastern equatorial Indian Ocean boundary indeed have a sufficiently wide meridional scale to induce a pressure signal at the Sri Lankan coast, which eventually propagates to the WCI as a coastal Kelvin wave. Second, local wind variations in the vicinity of Sri Lanka generate strong intraseasonal signals, which also propagate to the WCI along the same path. Sensitivity experiments indicate that these two new mechanisms (direct equatorial connection and local wind variations near Sri Lanka) dominate the WCI intraseasonal sea level variability, with the “classical” pathway around the Bay of Bengal only coming next. Other contributions (Bay of Bengal forcing, local WCI forcing) are much weaker.

We further show that the direct connection between the equatorial waveguide and WCI is negligible at seasonal timescale, but not at interannual timescales where it contributes to the occurrence of anoxic events. By providing an improved understanding of the mechanisms that control the WCI thermocline and oxycline variability, our results could have socio-economic implications for regional fisheries and ecosystems.
First field estimation of greenhouse gas emissions from European soil-dwelling Scarabaeidae larvae targeting the genus Melolontha
Authors: Görres Carolyn-Monika , Kammann Claudia
Published: March 2020

Arthropods are a major soil fauna group, and have the potential to substantially influence the spatial and temporal variability of soil greenhouse gas (GHG) sinks and sources. The overall effect of soil-inhabiting arthropods on soil GHG fluxes still remains poorly quantified since the majority of the available data comes from laboratory experiments, is often controversial, and has been limited to a few species. The main objective of this study was to provide first insights into field-level carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions of soil-inhabiting larvae of the Scarabaeidae family. Larvae of the genus Melolontha were excavated at various grassland and forest sites in west-central and southern Germany, covering a wide range of different larval developmental stages, and larval activity levels. Excavated larvae were immediately incubated in the field to measure their GHG emissions. Gaseous carbon emissions of individual larvae showed a large inter- and intra-site variability which was strongly correlated to larval biomass. This correlation persisted when upscaling CO2 and CH4 emissions to the plot scale. Field emission estimates for Melolontha spp. were subsequently upscaled to the European level to derive the first regional GHG emission estimates for members of the Scarabaeidae family. Estimates ranged between 10.42 and 409.53 kt CO2 yr-1, and 0.01 and 1.36 kt CH4 yr-1. Larval N2O emissions were only sporadically observed and not upscaled. For one site, a comparison of field- and laboratory-based GHG emission measurements was conducted to assess potential biases introduced by transferring Scarabaeidae larvae to artificial environments. Emission strength and variability of captive larvae decreased significantly within two weeks and the correlation between larval biomass and gaseous carbon emissions disappeared, highlighting the importance of field measurements. Overall, our data show that Scarabaeidae larvae can be significant soil GHG sources and should not be neglected in soil GHG flux research.
Creating a generic model of a high level waste (HLW) repository in crystalline rock and determining hydraulic parameters to investigate minimum requirements to the host rock for a safe storage location according to national German law
Authors: Weihmann Sarah , Maßmann Jobst
Published: March 2020

Nuclear power generation became popular in the 1950s in industrialised countries as an alternative to fossil energy sources to provide large amounts of low cost, low carbon energy. Currently 6% of the world’s energy supply is produced in 451 nuclear reactors across 30 countries. However, nuclear power generation has a serious disadvantage and hidden cost: the accumulation and disposal of spent fuel or high level nuclear waste (HLW) - notably highly radioactive nuclear fission products and the absence of suitable long-term storage solutions, threatening livestock and the environment. Sustainable disposal of HLW holds many challenges: fluid and heat transfer may induce strongly coupled undesirable thermal, hydrological, mechanical and chemical processes.

A crystalline rock repository construction license has been accomplished by Finland in 2015 for the first long-term HLW repository worldwide. In Germany, a consortium of federal offices is exploring the opportunity of establishing a long-term underground repository in crystalline rock for HLW as an alternative to potential repositories in salt rock and mudrock.

The aim of this research is to de-risk hypothetical storage solutions for long-term HLW repositories in Germany in crystalline rock. As no geological site must be alluded to for legal reasons during the repository site investigation process at the time being, flow is modelled for a generic fractured rock site based on academic studies of crystalline rock. An inverse problem approach is applied to investigate hydraulic site requirements for the long-term storage of HLW and provide footing for the analysis of coupled thermal, hydrological, mechanical and chemical processes. 

This work demonstrates progress towards finding a long-term storage solution for HLW in Germany through evaluating hydrological processes in a generic crystalline rock site. Through Oda analysis and simulating steady-state flow and particle tracking in a synthetic discrete fracture network (DFN), degrees of fracture connectivity and hydraulic conductivity of fractures have been identified for the hydraulic (boundary) conditions in a repository in crystalline rock.
Data Fusion on the CANDELA Cloud Platform
Authors: Yao Wei , Dumitru Octavian , Lorenzo Jose , Datcu Mihai
Published: March 2020

This abstract describes the Data Fusion tool of the Horizon 2020 CANDELA project. Here, Sentinel-1 (synthetic aperture radar) and Sentinel-2 (multispectral) satellite images are fused at feature level. This fusion is made by extracting the features from each type of image; then these features are combined in a new block within the Data Model Generation sub-module of the Data Fusion system.

The corresponding tool has already been integrated with the CANDELA cloud platform: its Data Model component on the platform is acting as backend, and the user interaction component on the local user machine as frontend. There are four main sub-modules: Data Model Generation for Data Fusion (DMG-DF), DataBase Management System (DBMS), Image Search and Semantic Annotation (ISSA), and multi-knowledge and Query (QE). The DMG-DF and DBMS sub-modules have been dockerized and deployed on the CANDELA platform. The ISSA and QE sub-modules require user inputs for their interactive interfaces. They can be started as a standard Graphical User Interface (GUI) tool which is linked directly to the database on the platform.

Before using the Data Fusion tool, users have to prepare the already co-registered Sentinel-1 and Sentinel-2 products as inputs. The S1tiling service provided on the platform is able to cut out the overlapping Sentinel-1 area based on Sentinel-2 tile IDs.

The pipeline of the Data Fusion tool starts from the DMG-DF process on the platform, and the data will be transferred via Internet; then local end users can perform semantic annotations. The annotations will be ingested into the database on the platform via Internet.

The Data Fusion process consists of three steps:

On the platform, launch a Jupyter notebook for Python, and start the Data Model Generation for Data Fusion to process the prepared Sentinel-1 and Sentinel-2 products which cover the same area;

On the local user machine, by clicking the Query button of the GUI, users can get access to the remote database, make image search and queries, and perform semantic annotations by loading quick-look images of processed Sentinel-1 and Sentinel-2 products via Internet. Feature fusion and image quick-look pairing are performed at runtime. The fused features and paired quick-looks help obtain better semantic annotations. When clicking on another ingestion button, the annotations are ingested into the database on the platform;

On the platform, launch a Jupyter notebook for Python, and the annotations and the processed product metadata can be searched and queried.

Our preliminary validation results are made based on visual analysis, by comparing the obtained classification maps with already available CORINE land cover maps. In general, our fused results generate more complete classification maps which contain more classes.
Effectiveness of Soil Conservation Practices as Climate Change Adaptations in Eastern US Corn-Soybean Production
Authors: Hill Robert , Salazar Natalia , Shirmohammadi Adel
Published: March 2020

Climate change is projected to affect the atmospheric variables that control crop production in the Eastern United States (US). Given that changes in these variables over the next decades are currently unavoidable, crop production will need to adapt to the expected changes in order to prevent or reduce yield losses. The main objectives of this study were: 1) to evaluate the effects of climate change on yields in rainfed corn (Zea mays L.)-soybean (Glycine max (L.) Merr.) rotation systems in the Eastern US and 2) to test two soil conservation practices—no tillage and winter cover cropping with rye (Secale cereale L.)—for their effectiveness as climate change adaptations in these systems. We used the Agricultural Policy/Environmental eXtender (APEX) model to simulate corn-soybean rotation systems in the future (2041‒2070) at nine land grant university research farms located throughout the Eastern US corn-soybean production belt from New York to Georgia. The simulated effects of climate change on yields varied depending on the climate model used, ranging from decreases to increases. Mean corn yields experienced decreases of 15‒51% and increases of 14‒85% while mean soybean yields experienced decreases of 7.6‒13% and increases of 22‒170%. Yield decreases were most common under the climate model predicting the highest increase in temperature and a reduction in precipitation, whereas yield increases were most common in the climate models predicting either a relatively small increase in temperature or a relatively large increase in precipitation. In many cases, the effects of climate change on yields worsened with time within the 30-year future period. The effects of climate change differed between the northern, central, and southern regions of the Eastern US, generally improving with latitude. Climate change generally affected corn yields more negatively or less positively than it did soybean yields. No tillage and rye cover cropping did not serve as effective climate change adaptations in regards to corn or soybean yields. In fact, planting rye after corn and soybeans reduced mean corn yields by 3.1‒28% relative to the control (no cover crop). We speculate that this yield decrease occurred because the rye cover crop reduced the amount of soil water available to the following corn crop.
Application of an artificial neural network to generate wave projections at southern African coasts
Authors: Soltau Felix , Hirt Matthias , Kelln Jessica , Santamaria-Aguilar Sara , Dangendorf Sönke , Jensen Jürgen
Published: March 2020

In the past decades, severe so called ‚compound events‘ led to critical high water levels at the coasts of southern Africa and as a consequence to property damage and loss of human life. The co-occurrence of storm surges, wind waves, heavy precipitation and resulting runoff increases the risk of coastal flooding and exacerbates the impacts along the vulnerable southern African coasts (e.g. Couasnon et al. 2019). To mitigate these high-impacts, it is essential to understand the underlying processes and driving factors (Wahl et al. 2015). As compound flooding events at southern African coasts are dominated by wind waves, it is of great importance to investigate the regional wave climate to understand the wave forcing as well as the origin of the wave energy.

Wind waves around southern African coasts are affected by the complex interactions between the Agulhas current and the atmosphere. In the research project CASISAC* we analyse the present evolution of the Agulhas Current system and quantify its impact on the future regional wave climate. Ocean waves contributing to high sea levels can be generated offshore resulting in swell or closer to the coasts by strong onshore winds. To identify responsible atmospheric pressure fields that force high wind wave events we apply a hybrid approach: (1) linking south hemispheric pressure fields with offshore wave data using an artificial neural network and (2) determine the prevailing nearshore wave conditions by regional numerical wave propagation models (SWAN). By validating the modelled nearshore wave data from hindcast runs with wave buoy records, this approach allows us to predict future extreme wind wave events and thus potential flooding. In a next step, extreme value analysis is used to determine future return periods of extreme wave events. These results can contribute to the development of more reliable adaptive protection strategies for southern African coast.

*CASISAC (Changes in the Agulhas System and its Impact on Southern African Coasts: Sea level and coastal extremes) is funded by the German Federal Ministry of Education and Research (BMBF) through the project management of Projektträger Jülich PTJ under the grant number 03F0796C

 

Couasnon, Eilander, Muis, Veldkamp, Haigh, Wahl, Winsemius, Ward (2019): Measuring compound flood potential from river discharge and storm surge extremes at the global scale and its implications for flood hazard. In: Natural Hazards and Earth System Sciences, Discussion Paper, S. 1–24. DOI: 10.5194/nhess-2019-205, in review.
Wahl, Jain, Bender, Meyers, Luther (2015): Increasing risk of compound flooding from storm surge and rainfall for major US cities. In: Nature Climate Change 5 (12), S. 1093–1097. DOI: 10.1038/nclimate2736.
Modeling the planform evolution of confined meandering rivers
Authors: Amini Hossein , Monegaglia Federico , Zen Simone , Lanzoni Stefano , Zolezzi Guido , Tubino Marco
Published: March 2020

The presence of lateral planimetric constraints preventing free migration and avulsion has a significant influence on the planform dynamics of river meanders. This particular confined kind of meandering rivers is definitely understudied, especially in comparison to freely migrating ones. Through a semi-analytical meander model, here we attempt to investigate the effect of the confined floodplain width through a morphodynamic modeling approach. The confined floodplain width is defined as the width between symmetric lateral confinement where the river is free to migrate, on the planform pattern and dynamics. Model results illustrate that weak confinement (i.e. loose floodplain boundaries) increases planform irregularity, with the river centerline preferentially lying close to floodplain boundaries, while strong confinement (tight floodplain boundaries) leads to a remarkable planform regularity, constituted by periodic sequences of sawtooth-shaped meanders. Bend orientation is reminiscent of the sub/super-resonant regime regardless of the confinement width. Model results are supported by good agreement with available field and remote sensing observation on selected case studies of confined meandering rivers in Canada previously studied by Nicoll and Hickin (2014).

 
Impact of the 536/540 CE double volcanic eruption event on the 6th-7th century climate using model and proxy data
Authors: van Dijk Evelien , Timmreck Claudia , Jungclaus Johann , Lorenz Stephan , Bajard Manon , Bostic Josh , Krüger Kirstin
Published: March 2020

The mid of the 6th century is an outstanding period and started with an unusual cold period that lasted several years to decades, due to the 536/540 CE double eruption event, with the strongest decadal volcanic forcing in the last 2000 years. Evidence from multiple tree ring records from the Alps to the Altai Mountains in Russia identified a centennial cooling lasting from 536 up to 660 CE. A previous Earth System Model (ESM) study with reconstructed volcanic forcing covering 535-550 CE like conditions already found that the double eruption led to a global decrease in temperature and an increase in Arctic sea-ice for at least a decade. However, the simulations were too short to fully investigate the multi-decadal cooling event and the atmospheric forcing from this double volcanic eruption alone may not be enough to sustain such a prolonged cooling. To better understand forced versus internal decadal climate variability in the first millennium we have performed mid 6th century ensemble simulations with the MPI-ESM1.2 for the 520-680 CE period. The ensemble consists of 10 realizations, which were branched of the MPI-ESM1.2 PMIP4 Past2k run, including the evolv2k volcanic forcing.

Here, we present results of this new set of the 6th-7th century MPI-ESM simulations in comparison to paleo-proxies. Summer surface temperatures are analyzed and compared with available tree-ring data, which fits very well for the entire 160 year period. As part of the VIKINGS project, special focus is placed on the impact of the 536/540 CE double volcanic eruption event on the surface climate in the Northern Hemisphere, in particular Scandinavia, Northern Europe and Siberia. The goal is to also compare the model data with new tree-ring and lake sediment proxies from southeastern Norway. Detailed comparison with proxy data will allow us to better understand the regional and seasonal climate variations of the 6th-7th century. Duration, strength and the possible mechanism for a long lasting volcanic induced cooling will be discussed.
Airborne GNSS reflectometry for coastal monitoring of sea state
Authors: Moreno Mario , Semmling Maximilian , Stienne Georges , Reboul Serge , Wickert Jens
Published: March 2020

Global Satellite Navigation Systems (GNSS) applications like navigation and positioning generally focus on the use of the direct radio signal broadcasted by the navigation satellites. From these signals, very highly precise coordinates can be obtained. However, there is a proportion of signals, that do not reach the receivers directly, that is, the signals that are reflected off Earth’s surface before reaching the receivers. That phenomenon gave way to one of the techniques that is taking an important role in the scope of GNSS remote sensing called GNSS-Reflectometry (GNSS-R). Due to the high reflection coefficient of the water and its importance within the climate system, the ocean is one of the surfaces with greatest interest in GNSS-R research projects. The objective of this study is to retrieve information about ocean height measured through the delay of the signal, and sea state and wind retrieval (ocean surface roughness) from the analysis of the signal amplitude.

During this study, GNSS-R measurements were executed along the North Sea coast between the cities of Calais and Boulogne, France, onboard of a gyrocopter. The setup consisted of a front-end data recorder with a right-handed circular polarization (RHCP) antenna. The campaign was conducted in July 2019 within a total of 9h 40m flight time. Each flight was performed at an altitude of about 800 m above sea level going on two legs forth and back along the coast. The legs differed in the distance from the coastline, of 700 m and 2 km, respectively.

Reflectometry signal processing involves three data levels. Level (0): The raw data samples of Syntony front-end receiver. Level (1): The Delay-Doppler Map (DDM) of the correlated reflected signal and the carrier phase, from which geophysical information can be derived. And Level (2): height estimation (from signal correlation in delay and frequency domain) and roughness estimation (from signal amplitude).

By using the DDM and the carrier phase delay the sea state shall be assessed including the achievable precision and reliability of estimates. An additional aim is also to validate the configuration in terms of the used platform, antenna setup, and flight design.
A 14.5 million-year geologic record of East Antarctic Ice Sheet fluctuations in the central Transantarctic Mountains, constrained with multiple cosmogenic nuclides
Authors: Bromley Gordon , Balter Alexandra , Balco Greg , Jackson Margaret
Published: March 2020

The distribution of relict moraines in the Transantarctic Mountains affords geologic constraint of past ice-marginal positions of the East Antarctic Ice Sheet (EAIS). We describe the directly dated glacial-geologic record from Roberts Massif, an ice-free area in the central Transantarctic Mountains, to provide a comprehensive record of ice sheet change at this site since the Miocene and to capture ice sheet response to warmer-than-present climate conditions. The record is constrained by cosmogenic 3He, 10Be, 21Ne, and 26Al surface-exposure ages from > 160 dolerite and sandstone erratics on well-preserved moraines and drift units. Our data set indicates that a cold-based EAIS was present, and similar to its current configuration, for long periods over the last ~14.5 Myr, including the mid-Miocene, Late Pliocene, and early-to-mid Pleistocene, with moraine ages increasing with distance from and elevation above the modern ice margin. We also report extremely low erosion rates over the duration of our record, reflecting long-term polar desert conditions at Roberts Massif. The age-elevation distribution of moraines at Roberts Massif is consistent with a persistent EAIS extent during glacial maxima, accompanied by slow, isostatic uplift of the massif due to subglacial erosion. Although our data are not a direct measure of ice volume, the Roberts Massif glacial record indicates that the EAIS was present and of similar extent to today during periods when global temperature was believed to be warmer and/or atmospheric CO2 concentrations were likely higher than today.
Numerical investigation of the performance of geothermal energy piles under different soil moisture conditions
Authors: Sani Abubakar Kawuwa , Singh Rao Martand
Published: March 2020

The use of foundation structures (piles) coupled to a heat pump system, commonly referred to as geothermal energy pile (GEP) system, provides a renewable energy solution of achieving space heating and cooling in buildings; whilst also being utilised for the structural stability of the overlying structures. The system operates by exchanging the low-grade heat energy within the shallow earth surface with the building, via the circulation of heat carrier fluid enclosed in a high-density polyethylene plastic pipes. In summer, heat energy is extracted from the building and transferred into the ground to achieve space cooling. While in winter, the ground heat energy is harnessed and transferred to the building to achieve sustainable space heating. This paper investigates the thermal performance of the GEP system under the effects of factors such as initial soil pore water content and ground water flow.

The study utilises coupled thermo-hydraulic finite element modelling and analyses to achieve the aim of this study. It was observed that the initial pore water volume and groundwater flow are very significant factors that determine the amount of heat energy that can be harnessed using the system.

 
U-Pb dating of carbonate-fluorapatite: a potential chronological tool for ancient marine sediments
Authors: O'Sullivan Gary , Mortimore Rory , Chew David , Daly Stephen
Published: March 2020

Carbonate-fluorapatite (CFA) is a common early diagenetic component of marine sedimentary sequences. Nodules, laminae and shell overgrowths or infills composed of CFA are relatively common features in phosphorites, carbonates and other marine sediments (e.g., Datillo et al., 2016). CFA U-Pb dating thus has potential application as a chronometer in a wide variety of ancient marine sediments, particularly in those marine sections lacking diagnostic faunal and/or floral assemblages, or well-dated volcanogenic horizons.

In order to test empirically whether accurate and precise U-Pb ages can be obtained from CFA using LA-ICPMS we have analysed CFA from a several marine sediment samples. These include samples of Cretaceous phosphatic chalk from southern England, phosphatic nodules from the Cretaceous of northern Ireland and western Scotland, and a sample from a laterally extensive Carboniferous phosphorite in western Ireland. Ages obtained from CFA in these rocks can be precise (as low as c. 0.55% 2SE error in one sample), and are all unimodal. U-Pb ages of CFA, however, range from stratigraphically-consistent ages to ages that record much younger events than their host rock stratigraphic ages.

While ‘ages’ obtained from CFA may be precise, what each of these ages represents geologically requires further study. The genetic relationship between phosphate and its host rock must be petrographically studied to understand the correspondence between the phosphatic and other components of these rocks in terms of their depositional and diagenetic histories. It is apparent that in some cases CFA will record deposition or early diagenesis, but that the U-Pb system in CFA can be overprinted by later tectonic events in other cases. In addition, whilst LA-ICPMS U-Pb dating of apatite (i.e. fluorapatite and chlorapatite) in crystalline rocks is now routine, the crystal structure and composition of CFA differs from apatite derived from igneous and metamorphic rocks, including the established fluorapatite U-Pb standards (e.g. Madagascar apatite, Thomson et al., 2012). Thus, assessment of matrix-matching effects will have to be undertaken to fully establish the CFA U-Pb chronometer.

Dattilo, B.F., Freeman, R.L., Peters, W.S., Heimbrock, W.P., Deline, B., Martin, A.J., Kallmeyer, J.W., Reeder, J. and Argast, A., 2016. Giants among micromorphs: were Cincinnatian (Ordovician, Katian) small shelly phosphatic faunas dwarfed?. Palaios, 31(3), pp.55-70.

Thomson, S.N., Gehrels, G.E., Ruiz, J., Buchwaldt, R., 2012. Routine low-damage apatite U-Pb dating using laser ablation-multicollector- ICPMS. Geochemistry, Geophys. Geosystems 13, 1–23. doi:10.1029/2011GC003928
Unique solvability of a system of ordinary differential equations modeling a warm cloud parcel and avoiding saturation adjustment
Authors: Porz Nikolas
Published: March 2020

The representation of cloud processes in weather and climate models is crucial for their feedback on atmospheric flows. Since there is no general macroscopic theory of clouds, the parameterization of clouds in corresponding simulation software depends fundamentally on the underlying modeling assumptions. We present a new model of intermediate complexity (a one-and-a-half moment scheme) for warm clouds, which is derived from physical principles. Our model consists of a system of differential-algebraic equations which allows for supersaturation and thus avoids the commonly used but somewhat outdated concept of so called 'saturation adjustment'. This is made possible by a non-Lipschitz right-hand side, which allows for nontrivial solutions. In a recent effort we have proved under mild assumptions on the external forcing that this system of equations has a unique physically consistent solution, i.e., a solution with a nonzero droplet population in the supersaturated regime. For the numerical solution of this system we have developed a semi-implicit integration scheme, with efficient solvers for the implicit parts. The model conserves air and water (if one accounts for the precipitation), and it comes with eight parameters that cannot be measured since they describe simplified processes, so they need to be fitted to the data. For further studies we implemented our cloud micro physics model into ICON, the weather forecast model operated by the German forecast center DWD.
Characterization of natural riverine colloids and their fate at increased salinity
Authors: Herzog Simon David , Gentile Luigi , Olsson Ulf , Persson Per , Kritzberg Emma
Published: March 2020

Riverine colloids are important carriers of macronutrients, trace metals and pollutants into marine waters. These carriers span in size from molecules over colloidal, to particulate matter. Our current understanding of the different riverine carrier phases and how they respond to salinity relies on indirect assessments based on size separation. Thus a division between iron (Fe)-rich and organic carbon (OC)-rich colloids has been made, where the former are predominantly found in the larger size fractions and the latter in the smaller fractions. While these applications have significantly improved our knowledge of the physical partitioning of the two main fractions, those phases are likely to overlap in size. To gain a more comprehensive understanding of Fe and OC colloids in boreal rivers and their fate at higher salinities, X-ray absorbance spectroscopy (XAS) and dynamic light scattering (DLS) were used to explore both Fe speciation and colloidal characteristics such as size and surface charge. The presence of two Fe phases in the river waters - Fe-organic matter (OM) complexes and Fe(oxy)hydroxides - were confirmed by XAS. Further, the DLS measurements, combined with filtration, identified three different particle size distributions. Fe (oxy)hydroxides were observed both as nanoparticles (10-40 nm) with positive surface charge, and larger aggregates with OM interactions (300-900 nm). An intermediate (100-200 nm) and negatively charged distribution was inferred to contain Fe-OM complexes. After increasing salinity, the smallest Fe (oxy)hydroxide nanoparticles were no longer detected in suspension. Unexpectedly, both the intermediate and largest size distributions were still detected in suspension at high salinity. The collective results from XAS and DLS suggest that Fe (oxy)hydroxides and Fe-OM complexes are both found across the wide size range studied, and that colloidal size does not necessarily reflect neither Fe speciation nor stability towards salinity induced aggregation. From this it follows that the fate of riverine nutrients, trace elements and pollutants depend largely on the carrier phase to which they are associated and not solely on the size.
Cooperation under conflict: a framework for participatory modeling under severe social and climate change pressures
Authors: Ocampo-Melgar Anahi , Barria Pilar , Chadwick Cristian
Published: March 2020

Hydrological modeling tools are usually used to obtain broad scale understandings of ecological and hydrological interconnections in a basin. They have also been presented as useful to support collaborative decision processes by visually displaying hydrological systems connections, uncertainties and gaps, as well conflicting preferences over water management strategies. However, many challenges remain at capturing and communicating the complexity of couple human-hydrological systems. The Aculeo basin in Chile is an internationally publicized case due to the disappearance of a 12 km2 lake that leaded to increasing conflicts over water scarcity and the cause of the catastrophe. A traditional hydrological model study and a separate collaborative agreement process were implemented in parallel to find answers and discuss solutions to the water scarcity crisis. The model initially designed to answer a single water balance question, was finally turned in a question-driven socio-hydrological modeling process used to explore a diversity of uncertainties emanating from the collaborative agreement process. Model development and some results of this integration are presented, displaying how science-policy process forces adjusting model structure, challenging official information and searching for alternatives sources and approaches to find answers. This research presents how a hydrological model can be used as a dynamic framework to address poor knowledge on the system behavior, disagreements on the water crisis causes and contradictions on the management options proposed. However, it also shows that participation can be an instance used by stakeholders to question and challenge the rigidity, scope and accuracy of the model information being presented. Therefore, flexible approaches and research agendas should support the exploration of this type of synergies towards more collaboration and production of useful and legitimate socio-hydrological models. 
Uncertainty quantification in geological modelling by Hessian-informed MCMC
Authors: Liang Zhouji , Wellmann Florian
Published: March 2020

Uncertainty quantification is an important aspect of geological modelling and model interpretation. Recent developments in geological modelling allow us to view the inversion as a problem in Bayesian inference, incorporating the uncertainties in the observations, the forward models and the prior knowledge from geologists. The sampling method Markov chain Monte Carlo (MCMC) is then often applied to solve this inference problem. However, this stochastic modelling approach is limited as the number of parameters increases to higher dimensions. To ensure an efficient sampling in a high dimensional problem, we take advantage of recent advances using Hessian-based MCMC methods in this work. The Hessian of the negative log posterior with respect to the input parameters is evaluated at the Maximum a Posteriori (MAP) point. A Laplace approximation of the posterior at the MAP is then given by the inverse of the local Hessian. This sampling approach provides a potentially less computationally expensive and more efficient way for high dimensional geological inverse modelling, especially in cases where parameters are highly correlated, a situation that commonly arises in geological modelling.
Application of the Surface Energy Balance in Richard's equation-based model using climatic data to calculate soil evaporation
Authors: Cárdenas-Castillero Gustavo , Arbelaez Juliana
Published: March 2020

This research aims to observe the behaviour between heat flow at the limit of the unsaturated area and the earth's surface (evaporation) through different methods based on the surface energy balance. This behavior has been determined by the DRUtES. DRUtES is a free software able to determine the evaporation in the surface using climate and hydraulic parameters determined by the Richard equation. Richards’ equation describes the flow of water in an unsaturated porous medium due to the actions of gravity and capillarity neglecting the flow of the non-wetting phase, usually air (Farthing & Ogden, 2017). 

 

The results obtained have been compared with the Penman-Monteith potential evapotranspiration model, this one as a referenced value. The results obtained help to understand the loss of water in the unsaturated area. This first approach using DRUtES and evaporation methods will allow a deeper investigation in the future regarding the impact of climate change on climate variables and their effects on soil moisture (unsaturated area) and natural aquifer recharge.

Key words: Evaporation, surface energy balance, Richard's Equation, zone unsaturated, Penman-Monteith.
Investigating H2O contents in clinopyroxene from explosive versus effusive eruption products from Merapi volcano, Indonesia
Authors: Dimitriou Dimitrios , Troll Valentin , Weis Franz , Seraphine Nadhirah , Deegan Frances , Skogby Henrik , Humaida Hanik , Gertisser Ralf
Published: March 2020

The 2010 eruption of Merapi produced pyroclastic deposits and lava flows that are compositionally very similar, raising the question as to the underlying reason of the differences in eruptive styles between the various phases of the 2010 eruptive events. To test whether primary magmatic volatile content is the reason for the different eruption styles, we analyzed magmatic water contents in nominally anhydrous clinopyroxene crystals contained in lava and ash from the 2010 eruptive events. We utilized two analytical approaches: (i) Fourier-transform infrared spectroscopy (FTIR) analysis of fresh clinopyroxene from the ash and lava samples and (ii) FTIR analysis of clinopyroxene both prior to and after experimental re-hydration. By employing calculated partition coefficients, we determined the magmatic water content of the magma from which the various crystals grew. The magmatic water content determined from the unmodified clinopyroxenes from lava samples yield a range of 0.35 wt.% to 2.02 wt.% H2O, whereas magmatic water contents determined from untreated clinopyroxene contained in the ash samples range between 0.04 and 3.25 wt.%, with two outliers at 4.62 and 5.19 and wt.%, respectively. In contrast, for the rehydrated crystals the range for lava derived clinopyroxene crystals is between 1.94 and 2.19 wt.% and for ash between 1.74 and 2.66 wt.%, with two crystals at extreme values of 0.85 and 3.20 wt.%. We interpret these results to indicate that crystals from different populations are present in the 2010 eruptive products, with the dominant group reflecting relatively low magmatic H2O contents (around 2 wt.%) due to storage in shallow magma reservoirs and pockets at high levels within the Merapi plumbing systems (e.g. top 3 km). The overall higher H2O range and the occasionally more extreme values recorded in clinopyroxenes from ash deposits may then represent the presence of a crystal population that last equilibrated at deeper levels and at higher water contents, i.e. these crystals derive from the replenishing magma that activated the shallow portion of the plumbing system during the 2010 events. While this is work in progress, our results so far seem to suggest that the pyroclastic deposits of the 2010 Merapi eruption may contain a higher fraction of clinopyroxene derived from ‘deeper magma’ with higher H2O contents then what we have detected in associated lavas.
Analysis of sprite events during small-scale winter thunderstorms in northern Europe
Authors: Pizzuti Andrea , Soula Serge , Mlynarczyk Janusz , Bennett Alec , Fullekrug Martin
Published: March 2020

Lightning occurrence throughout Europe is at a minimum in winter and mostly confined around the coastlines of the Mediterranean. Limited extent winter thunderstorms at higher latitudes are nevertheless found to produce intense CG strokes that may result in short-lived optical phenomena above thunderstorms in the region between the stratosphere and the lower ionosphere that are collectively referred to as transient luminous events (TLEs). Recent examples of sprite observations have been reported in northern Europe, at latitudes larger than about 49N, during very low flash-rate and small-scale winter storms. This study focuses on the characteristics of the sprite-producing strokes and the context in which they occurred. The sprite parent strokes are identified through the Météorage lightning detection network, providing additional information on the polarity and the peak current. A further characterization of the electromagnetic signal associated with these events is performed combining data from a series of quasi-electrostatic lightning sensors deployed in UK, a wideband ELF-VLF-LF radio receiver at the University of Bath (UK) and an ELF station in Poland, used for the calculations of the related current moment waveform (CMW) and charge moment change (CMC). The characteristics of the thunderstorm, as the cloud top temperature (CTT), the size and the meteorological context, are considered in order to better understand the conditions leading to the observed events.