bluuebunny/crossref_metadata_2025 huggingface dataset:
Using vegetation dynamics to generate forest species and crop type maps as well as land-use intensity measures to support carbon stock estimations
Authors: Doktor Daniel , Lange Maximilian , Preidl Sebastian
Published: March 2020

Land-cover / land-cover change together with varying land-use intensity are forces of global importance especially within the last decades. This concerns the conversion of natural ecosystems into agricultural land, but also the intensified use of agricultural areas which both translate into respective (decreasing) carbon stocks. Unfortunately, land-cover information at field level is often missing at larger scales. While there has been some progress for a more detailed spatial and thematic characterisation within the domain of arable land, especially forest and grassland ecosystems are largely rudimentarily described. Here we present a framework to address to above mentioned issues which provides field level information on crop types, tree species and land-use intensity in grasslands as well as the underlying phenology at a national scale (Germany).

We used Sentinel 2 a/b time series (all observations between 2016-2019) at 20 m spatial resolution. For training and validation InVeKoS (LPIS) data, forest inventories as well as farmland management data covering considerable parts of Germany were employed. The number of mowing and fertilisation events as well as livestock density served as indicators to estimate land-use intensity. Crop type and tree species classification relied on a novel compositing approach which is tailor-made to operate in temperate (often cloudy) climates and is easily scalable from a local to a national level. Land-use intensity in grasslands together with land-surface phenology could be inferred via time series analysis on the seasonal evolution of vegetation indices. Both classification as well as intensity estimates also included machine learning methods (randomForest).

We could achieve ca. 90 % overall classification accuracy for crops (19 types) and ca. 75 % for tree species (4 deciduous, 4 conifers) across Germany. Crop type and tree species specific phenology varied according to underlying topography and climate conditions. We identified between 1-5 annual mowing events across Germany, for most regions 2-3. Land-use intensity estimates were in line with areas typical of high/low livestock density. Altogether, this framework and its products can well serve as a basis to support robust carbon stock estimates for different ecosystem up to the national scale.
Nonlinear rainfall-runoff modelling of semi-arid regions using ERA5 data
Authors: Fidal James , Kjeldsen Thomas
Published: March 2020

Semi-arid regions are very challenging environments for rainfall-runoff modelling due to the high spatial variation of rainfall alongside extreme wet and dry periods resulting in distinctly different hydrological conditions within the same catchment. In order to account for the extreme wet and dry periods, a new non-linear rainfall-runoff model has been developed. The non-linear model is capable of capturing the quick recessions observed during the wet periods alongside accounting for very little flows during the dry periods. The ability of the new model was assessed by comparing the linear version with the non-linear version on two nested catchments located within South Africa. The catchments areas are 183 and 328 km2 and include 15% and 10% urbanisation respectively. The average rainfall during the wet period (May-Sep) is approximately 130mm per month with the dry period (Jan- Apr and Oct-Dec) averaging less than 35mm per month for the years 2000-2017. To challenge the problem of high spatial variation of rainfall, the fifth generation of ECMWF atmospheric reanalysis of the global climate ERA5 data is used. Both locally collected gauge and ERA5 reanalysis data were compared to show that the ERA5 data set was more capable than the local gauge in rainfall-runoff simulations with performance increases of up to 30\%. When comparing the default linear model and the non-linear model results based on ERA5 data showed the same level of performance for each model. However when flow duration curves and hydrographs were examined results showed that the linear model was not capable of adequately capturing the low flows of the catchment, whilst at the same time overestimating the high flows. Conversely, the non-linear model was capable of capturing the low flows recession and whilst it did also overestimate peak flows it was to a lesser extent than the linear model.
Is breakthrough of solute impacted by the edges of the columns in the case of macropored systems?
Authors: Raimbault Jérôme , Lassabatere Laurent , Peyneau Pierre-Emmanuel , Courtier-Murias Denis , Béchet Béatrice
Published: March 2020

In natural systems, preferential flow is the rule rather than the exception. Non-uniform and preferential flows significantly impact mass transport, and by this way most of geochemical processes and pollutant dispersion in the environment. Laboratory columns are experimental devices used for the monitoring of solute transfer through porous. In particular, several studies used such experimental devices for characterizing mass transfer through heterogeneous systems and macropored systems. However, the design of these devices and its impacts on the experimental results has never been investigated in depth so far. In particular, the edge effect is rarely questioned and the transfer is always hypothesized to correspond to a fully developed flow (i.e., flow in an equivalent infinite system). In this study, we question this hypothesis both experimentally and numerically for the case of a macropored system. Tracer elutions, magnetic resonance imaging (MRI), and modeling using multiphysics approaches (Comsol) are conducted to demonstrate that flow is affected by edge effects close to the inlet and the outlet of the column, and that the presence of filters (used to prevent particles from exiting the system and clogging the outlet) do impact the flow and transfer breakthrough. Consequently, these edge effects should be considered when analyzing the results and concluding on the involved processes, in particular for the case of soils and systems with macropores.
Evaluation of three global gradient-based groundwater models in the Mediterranean region
Authors: Ben-Salem Nahed , Wachholz Alexander , Rode Michael , Borchardt Dietrich , Jomaa Seifeddine
Published: March 2020

The Mediterranean region is recognized as one of the most sensitive regions in the world to water scarcity, due to both climate change and consistently increasing anthropogenic pressures. Groundwater is considered as a strategic freshwater reserve in the Mediterranean region; however, its status remains poorly characterized and its total budget uncertain. In recent years, groundwater modelling has moved from local to regional/global scale, offering insights into the status of data-scarce regions. However, it remains unclear to what extent those models can be used to support management decisions. This study aims to compare and evaluate the performance of three groundwater models to represent the steady-state groundwater levels in the Mediterranean region. Thus, the groundwater models of Reinecke et al. (2019), de Graaf et al. (2017) and Fan et al. (2013) will be utilized in this study. The preliminary results indicate that, in the northern part of the Mediterranean region, the models of Reinecke et al. (2019) and de Graaf et al. (2017) predict similar water table patterns. However, both models simulate completely different groundwater regimes in the desert regions; the predicted groundwater table of de Graaf et al. (2017) model is significantly deeper than of Reinecke et al. (2019) model. This could be, probably, because of the calibration of de Graaf et al. (2017) model compared to Reinecke et al. (2019) model, which is not yet calibrated. A detailed comparison between simulated and measured water table depth of different Mediterranean aquifers having different climatic, geologic and anthropogenic conditions will be presented.

References

Reinecke, R. et al. Challenges in developing a global gradient-based groundwater model (G3M v1.0) for the integration into a global hydrological model. Geosci. Model Dev 12, 2401-2418 (2019).

de Graaf, I. et al. A global-scale two-layer transient groundwater model: Development and application to groundwater depletion. Adv. Water Resour 102, 53-67 (2017).

Fan, Y. et al. Global patterns of groundwater table depth. Science 339, 940-943 (2013).

 
Stress-induced melting of plagioclase during laboratory earthquakes
Authors: Incel Sarah
Published: March 2020

Impact rocks often reveal particular structures, e.g. shock-induced amorphization and melting of crystals, that formed due to high stresses during shock metamorphism. This experimental study presents four granulite samples that were deformed in a D-DIA apparatus at 2.5 GPa and 3 GPa and at either 1023 K, 1173 K, or at 995 to 1225 K. During deformation of two samples (2.5 GPa and either 995-1125 K or 1173 K) 82 and 794 acoustic emissions (AEs) were recorded, respectively, whereas less than 10 AEs were recorded while deforming the other two granulite sample (3 GPa and 995-1225 K; 2.5 and 1073 K). Microstructures of the samples that emitted 82 and 794 AEs reveal amorphous patches that are absent in the samples corresponding to the runs in which <10 AEs were recorded, indicating a link between AE-activity and amorphization of plagioclase. The contacts between amorphous patches and host-plagioclase crystals are very sharp and amorphization predominantly occurred along two distinct planes inclined at approx. 45° towards the direction of maximum compression. Surrounding the patches, the hosts show extensive fragmentation. Chemical analyses of the amorphous patches demonstrate an enrichment in potassium and silicon relative to the initial plagioclase chemistry and the growth of euhedral quartz crystals within the patches. Such microstructures were previously found in naturally or experimentally shocked rocks and interpreted as shock melts. The occurrence of structures, revealing striking similarities to shock melts, in experimental samples that underwent embrittlement at high-pressure, high-temperature conditions below the sample’s solidus (~1377 K) suggests melting due to elevated transient stresses, e.g. during rupture processes.
Flood severity along the Usumacinta River, Mexico: identifying the anthropogenic signature of tropical forest conversion.
Authors: Horton Alexander , Nygren Anja , Diaz-Perera Miguel , Kummu Matti
Published: March 2020

Global climate change and anthropogenic activities are disrupting flood frequency-magnitude distributions along many of the world’s large rivers, posing critical threats to rising populations and infrastructure. Isolating a single discharge signal amidst the multitudes of competing anthropogenic signatures is a persistent, yet important challenge if we are to mitigate against their negative consequences. The Usumacinta River in southern Mexico provides an ideal opportunity to study an anthropogenic driver in isolation: tropical forest conversion. The Usumacinta flows unobstructed along the entirety of its course, meaning the 55-year discharge record (1959 – 2014) represents the river’s response to a changing landscape under climatic variability. This paper employs a novel approach to disentangle the anthropogenic signal from climate variability, and provides valuable insight into the impact of forest conversion on flood severity.

Here we analyse continuous daily time series of precipitation, temperature, and discharge to identify long-term trends, and compare ratios of catchment-wide precipitation totals to daily discharges in order to account for climatic variability, and identify an anthropogenic signature of tropical forest conversion at the intra-annual scale. We successfully reproduce this signal using a distributed hydrological model (VMOD), and demonstrate that the continued conversion of tropical forest to agricultural land will further exacerbate large scale flooding.

We find statistically significant increasing trends in annual minimum, mean, and maximum discharges that are not evident in either precipitation or temperature records. We also find that mean monthly discharges have increased between 7 and 75% in the past decade, in contrast to mean monthly precipitation, which has decreased during the dry-season. Model results demonstrate that forest cover loss is responsible for raising the 10-year return flood by 20%, and the total conversion of forest to agricultural land may result in an additional 23% rise. Meaning the return period for a flood on the order of the 2008 peak discharge would fall from the current estimate of 41 years to just 12 under the total forest conversion scenario.

These findings highlight the need for a holistic approach to catchment-wide land management in developing tropical regions that weights the benefits of agricultural expansion against the consequences of increased flood prevalence, and the economic and social costs that they incur.
A Parametrization for Triad Interactions of Internal Gravity Waves in Varying Background Flows for WKBJ Ray-Tracing Methods
Authors: Voelker Georg Sebastian , Akylas Triantaphyllos , Achatz Ulrich
Published: March 2020

Internal gravity waves are a well known mechanism of energy transport in stratified fluids such as the atmosphere and the ocean. Their abundance and importance for various geophysical processes like ocean mixing and momentum deposition in atmospheric jets are widely accepted. While resonant wave-wave interactions of monochromatic disturbances have received intensive study, little work has been done on triad interactions between wave trains that are modulated by a variable mean flow.

Using the method of multiple scale asymptotics we consider a weakly non-linear Boussinesq WKBJ theory for interacting gravity wave trains propagating through a finite amplitude background flow. Consequently the wave trains are allowed to spectrally pass through resonance conditions and exchange energy when sufficiently close to resonance. We find a global optimal threshold for the deviation from resonance and derive a corresponding parametrization for the triad interaction applicable to ray tracing schemes.

We test the theory with idealized simulations in which two wave trains generate a third by passing through resonance in a sinusoidal background shear flow with varying vertical scales. Comparing WKBJ simulations with wave resolving large eddy simulations we find qualitative and quantitative agreement. Furthermore we assess the impact of the strength of the modulation as well as the effect of the wave amplitudes on the energy exchange between the interacting wave triad.
Biogeochemistry of the Western Irish Shelf: The role of picoplankton as assessed by flow cytometry and remote sensing
Authors: Mullins Monica , Croot Prof. Peter
Published: March 2020

A key challenge in understanding how climate change will impact continental shelf ecosystems is to understand the physical and chemical drivers of primary productivity in these systems and to assess the natural variability on spatial and temporal scales. Presently the impacts of climate change on ecosystem processes/services along the western Irish shelf are poorly known due to a lack of in situ data, this is most notable for the contribution from picoplankton. In this project, we were able to take advantage of the annual WESPAS Fisheries surveys along the Western Shelf waters from 47°N northwards to 58°30’N onboard the Celtic Explorer to obtain biogeochemical data for this region. A number of key Essential Ocean Variables (EOVs) have been measured annually since 2016; including nutrients, baseline optical measurements of CDOM and FDOM, phytoplankton abundance via flow cytometry (Accuri C6) and Chlorophyll concentration in surface waters. Utilizing data from the Sentinel series of satellite allows us then to examine in more detail the potential drivers of picoplankton abundance and their impact on C and other elemental biogeochemical cycles in these waters.

The overarching aim of this work is to provide baseline data for developing biogeochemical climatologies for this region and for determining Good Environmental Status (GES) as per the EU Marine Strategy Framework Directive.

This publication/presentation* has emanated from research supported in part by a research grant from Science Foundation Ireland (SFI) under Grant Number 13/RC/2092 and is co-funded under the European Regional Development Fund and by PIPCO RSG and its member companies.
MICRU effective cloud fractions for S-5P/TROPOMI
Authors: Sihler Holger , Beirle Sreffen , Borger Christian , Wagner Thomas
Published: March 2020

We present results of effective cloud fractions retrieved from measurements of the TROPOspheric Monitoring Instrument (TROPOMI) using the Mainz Iterative Cloud Retrieval Utilities (MICRU) algorithm. Cloud fraction (CF) data is used to study the distribution of clouds in general. Furthermore, CF is a crucial input parameter for retrievals of tropospheric trace gases from satellite measurements in the UV/vis spectral region because CF errors may even dominate vertical column density (VCD) retrieval errors of tropospheric trace gases.

The MICRU algorithm has been specifically developed to retrieve small cloud fractions (CF<20%) at high accuracy in order to improve retrievals of tropospheric trace gases. Here, MICRU is applied to TROPOMI data offering a more than 100 times higher spatial resolution compared to GOME-2 (Global Ozone Monitoring Experiment-2), on which it was previously applied. Hence, MICRU CF can be used as an alternative to the operational CF product.

The most important feature of MICRU is the derivation of the minimum reflectance map from the measurements themselves. The algorithm builds on the assumption that the surface is dark compared to clouds, and it is therefore limited to regions not permanently covered by clouds, ice or snow. In particular, the MICRU algorithm applies four parameters to constrain interferences with surface BRDF effects like sun glitter and shadowing. Our approach features a lower threshold map parameterised by time, viewing zenith angle, scattering angle, and reflection angle.

We demonstrate that MICRU, compared to the operational cloud fraction algorithms OCRA and FRESCO, interferences less with viewing angle, solar glitter, and shore lines and, hence, significantly improves the determination of cloud fractions. Furthermore, CF features made visible by the unprecedented spatial resolution of TROPOMI are discussed.
DIY Rocket Launcher
Authors: Abdul Mutalib Norhailmi
Published: March 2020

Space science is often considered irrelevant by education authorities because it has no apparent economic value. Students are full of imagination and they need challenges to go further. By giving them a task to create their own version of a rocket launcher which may only cost USD4, the students were able to show their creativity using simple and recycled things around them.

  My poster presents one of the activities I realized with my students.

Subject: Space Science

Grade: 15 years old

Duration: Two class periods

  The objectives are for the students to be able to learn about the basic concept of rocket launching and to give them exposure to Space science. It is an interdisciplinary STEM activity that involves science, handwork, mathematics. To our surprise, a group of special needs students were also part of the successful project.  
Comparisons between Sentinel-5P TROPOMI NO2 and the European ensemble air quality forecasts of CAMS
Authors: Douros John , Eskes Henk , Veefkind Pepijn
Published: March 2020

In our contribution we present comparisons between TROPOMI observations of NO2 (nitrogen dioxide) and the CAMS regional forecasts and analyses for Europe. The Sentinel-5P TROPOMI instrument, launched in October 2017, provides unique observations of atmospheric trace gases at a high resolution of about 5 km, resolving individual point sources, medium-scale towns, roads and shipping routes. The datasets have a global daily coverage, but these datasets are especially well suited to test high-resolution regional-scale air quality models and provide valuable input for emission inversion systems. In Europe, the Copernicus Atmosphere Monitoring Service (CAMS) has implemented a regional air quality forecasting capability for Europe based on an ensemble of 7-9 European models, available at a resolution of 0.1x0.1 degree.

We discuss the different ways of making these comparisons, and present the quantitative results for summer and winter months and individual days. The models generally capture the fine-scale daily and averaged features observed by TROPOMI in much detail. We show that replacing the global 1x1 degree a-priori information in the retrieval by the regional 0.1x0.1 degree profiles of CAMS leads to significant changes (increases at hotspot emission locations) in the TROPOMI retrieved tropospheric column. Apart from comparing with the ensemble model, we also present the results for the individual CAMS models. 
Upper Cretaceous Stratigraphy and Volcanism in the İğneada region, Pontides, NW Turkey
Authors: Sağlam Ezgi , Duzman Turgut , Okay Aral I.
Published: March 2020

The Pontide Upper Cretaceous magmatic arc can be traced for over 1000 km along the southern Black Sea coast from Georgia to Bulgaria.  The arc extrusive sequence is well-exposed in the İğneada region in Thrace close to the Bulgarian border. The Upper Cretaceous sequence in İğneada region overlies the schists and phyllites of Strandja Massif with an unconformity. It  has a thickness of over 700 meters and consists at the base of Cenomanian shallow marine sandy limestone, which pass up into pelagic limestone, marn and volcanogenic siltstone with Turonian planktonic foraminifera, including Marginotruncana pseudolinneana, Marginotruncana marginata, Whitenella sp., Whitenella praehelvetica, Muricohedbergella sp.  This indicates that the arc volcanism in the region started in the Turonian. The pelagic limestone, marl, and calcareous siltstone series passes up into a volcanic-volcaniclastic sequence of andesitic tuff, lapillistone, agglomerate, andesitic and basaltic-andesitic lava flows. The volcaniclastic rocks are intercalated with lava flows and with rare pelagic limestone and shale beds. Although it is disrupted by several faults, the volcanic sequence can be traced from older to younger along the coast of İğneada. The sequence starts with andesitic volcaniclastic rocks and lava flows, and changes to basaltic-andesitic and then, again to andesitic rocks. The ocean floor alteration, which is found in all volcaniclastic and volcanic rock samples, and the intercalated pelagic limestones show that the rocks were deposited in deep submarine conditions in an intra-arc to fore-arc environment. Campanian (80.6 ±1.5 Ma) U-Pb zircon ages, which are obtained from the andesitic tuffs at the base of the volcanic-volcaniclastic sequence, indicate a continued magmatism from Turonian to Campanian.
The health hazards and impacts of volcanic ash: an interdisciplinary journey towards effective mitigation, protection and communication
Authors: Horwell Claire J.
Published: March 2020

The eruption of Mount St. Helens in 1980 exposed a large population to volcanic ash that was found to contain cristobalite – a crystalline silica polymorph and known carcinogen. This event triggered an array of epidemiological, toxicological and geochemical studies to assess the toxicity of ash, marking the birth of a new field of research. This talk will take you on an interdisciplinary journey through the work conducted since the 1980s, which has discovered both biological mechanisms in favour of volcanic ash toxicity and inherent physicochemical characteristics of ash particles that may render the silica surfaces non-toxic. A sparsity of longitudinal clinical and epidemiological studies following eruptions means that medical evidence for chronic ash pathogenicity is lacking, but other research has shown that acute exposures to volcanic ash can exacerbate existing respiratory conditions. Additionally, a multitude of techniques and protocols have been developed for rapid, eruption-specific health hazard assessment, but conducting these assessments in a crisis is very challenging. In the absence of definitive information about the harmfulness of ash, many exposed people choose to protect themselves as a precaution, or are advised to do so by agencies, so recent research has focussed on providing them with the knowledge to do that effectively. This laboratory and community-based research, involving collaborations among geoscientists, exposure scientists, social scientists, medical ethicists, agency and community representatives, has yielded critical insight into a chain of communication from researcher, through various local ‘authorities’, to the actions taken by communities. The findings have led to changes in humanitarian and individual practice and have opened up new pathways to effective uptake of evidence-based advice through co-designed informational products. 
Fault slip envelope: A new parametric investigation tool for fault system strength and slip
Authors: Soliva Roger , Maerten Frantz , Maerten Laurent , Mattila Jussi
Published: March 2020

The fact that inherited fault systems show strong variability in their 3D shape provides good reasons to consider the strength of the Earth’s brittle crust as variably anisotropic. In this work we quantify this strength anisotropy as a function of fault system complexity by combining 3D boundary element model, frictional slip theory and fast iterative computation method. This method allows to analyze together a very large number of scenarios of stress and fault mechanical properties variations through space and time. Using both synthetic and real fault system geometries we analyze a very large number of numerical simulations (125,000) to define for the first time macroscopic rupture envelopes for fault systems, referred to as “fault slip envelopes”. Fault slip envelopes are defined using variable friction, cohesion and stress state, and their shape is directly related to the fault system 3D geometry and the friction coefficient on fault surfaces. The obtained fault slip envelopes shows that very complex fault geometry implies low and isotropic strength of the fault system compared to geometry having limited fault orientations relative to the remote stresses, providing strong strength anisotropy. This technique is applied to the realistic geological conditions of the Olkiluoto high-level nuclear waste repository (Finland). The model results suggests that Olkiluoto fault system has a better probability to slip under the present day Andersonian thrust stress regime, than for the strike-slip and normal stress regimes expected in the future due to the probable presence of an ice sheet. This new tool allows to quantify the anisotropy of strength and probability of slip of 3D real fault networks as a function of a wide range of possible geological conditions an mechanical properties. This significantly helps to define the most conservative fault slip hazard case or to account for potential uncertainties in the input data for slip. This technique therefore applies to earthquakes hazard studies, geological storage, geothermal resources along faults and fault leaks/seals in geological reservoirs.
High resolution Aerosol Radiative Effects over Europe using detailed optical properties from the Chemical Transport Model PMCAMx
Authors: Korras Carraca Marios Bruno , Manetas Dimitris , Patoulias David , Pandis Spyros , Hatzianastassiou Nikolaos , Vardavas Ilias , Matsoukas Christos
Published: March 2020

Natural and anthropogenic aerosol particles are major drivers of the Earth’s radiation budget, which they affect directly (through scattering and absorption) and indirectly (through modification of cloud scattering and precipitation properties), while they semi-directly influence atmospheric stability and convection, mainly through modification of solar radiation absorption by the atmosphere. Despite the important climatic role of aerosols, large uncertainties in their radiative effects remain due to limited knowledge of the aerosol spatio-temporal distribution and physico-chemical properties. The interaction of aerosols with radiation is strongly dependent on their optical properties, which in turn are controlled by the particles’ size distribution, shape, chemical composition and mixing state. In order to accurately estimate the magnitude of the aerosol direct radiative effect (DRE), detailed knowledge of their optical properties with high spatial and temporal resolution is required.

The European continent is a region of particular interest for studying atmospheric aerosol effects, because of the presence of  numerous and varying sources of particles and their precursors, such as industries, large urban centers and biomass burning, especially when combined with high levels of solar insolation during summer. In this study, the aerosol DRE over Europe is examined using the FORTH deterministic spectral radiative transfer model (RTM) and aerosol data from the chemical transport model PMCAMx. Chemically and size resolved aerosol concentrations predicted by PMCAMx are combined with a Mie model to calculate key aerosol optical properties (i.e. vertically resolved aerosol optical depth, single scattering albedo and asymmetry parameter) that are necessary to compute aerosol DRE using the RTM. The Mie model takes into account concentrations of organics, black carbon, sulfate, nitrate, ammonium, chlorine, sodium, water, and crustal material, and calculates aerosol optical properties assuming that the aerosol particles of the same size are internally mixed. The DRE is estimated at the Earth’s surface, within the atmospheric column and at the top of the atmosphere (TOA), at high spatial and temporal resolution (36 × 36 km grids, 27 vertical layers, hourly), during June and July 2012.

Initial modelling results reveal that DREs exhibit significant spatio-temporal variability, due to the heterogeneity of source emissions rates, mostly with regard to wildfires, and the varying synoptic conditions. Emphasis is thus given to biomass burning aerosols, which are among the most significant radiative forcing agents in Europe during summer. Their relative forcing is computed by performing model computations with and without biomass burning emissions.
Plagioclase as a witness of syn-eruptive degassing in rhyolitic magmas
Authors: Ellis Ben , Neukampf Julia , Laurent Oscar , Steinmann Lena , Weyer Stefan , Magna Tomas , Ubide Teresa , Bachmann Olivier
Published: March 2020

Lithium (Li) is one of the fastest diffusing elements in most geological media and so has the potential to provide information about processes occurring on timescales too short to be captured by other proxies.  These processes may be of fundamental importance both in terms of understanding what happens during explosive volcanism and for defining where lithium, an element of increasing economic importance, ends up.  To investigate the fate of Li, we studied in detail the 1.30 Ma Mesa Falls Tuff (MFT) from the Yellowstone volcanic field (USA).  MFT is a typical rhyolite of the Yellowstone system containing an anhydrous mineral assemblage of sanidine, quartz, plagioclase, clinopyroxene, fayalite, orthopyroxene and accessory phases.  We focussed on plagioclase crystals that have a strong gradient in Li contents from cores at ~25 ppm to rims with ~ 5 ppm.  This notable decrease in Li abundance is decoupled from changes in other major and trace elements.  δ7Li values measured by fs-LA-MC-ICPMS in the plagioclase crystals reveal that cores are about 5 ‰ lower than rims.  Taken together, the Li abundance and isotopic data make a compelling case for the plagioclase attempting to react to a sudden change in Li abundance in the surrounding melt.  Diffusion modelling of these gradients indicates that this sudden Li drop in the melt occurred over timescales of tens of minutes prior to quenching.  The volatile behaviour of Li implied by this result finds support in Li concentrations measured in quartz-hosted melt inclusions that reach 400 ppm while groundmass glass Li contents are much lower (36-55 ppm).  While equilibrium fractionation of stable isotopes is minimised at high temperatures, the large-magnitude, rapid loss of lithium from the melt phase may allow kinetic isotopic fractionation to occur, as recorded in the plagioclase crystals.  With glass / groundmass both volumetrically dominant and the main repository of Li in virtually all volcanic deposits, further consideration of how syn-eruptive processes may affect the bulk Li identity of a sample is warranted.        

 
Determination of the role and value of water for the sustainable development of Asian cities
Authors: Fukushi Kensuke
Published: March 2020

Water is a key element to the economic development and plays vital role in various activities including commercial, households, services, water-landscape, and water transport etc. A good water environment in cities has been achieved in developed countries (for e.g. Japan) through implementation of central wastewater treatment and sewerage systems. However, the development of sustainable water management and introducing a new sewage management method is challenging for the cities of developing nations in Asia in terms of having high capital, energy consumption and the technologies. This paper is evaluating the role and importance of sustainable development of water management methods and systems. Our findings suggest that the developed and developing countries must come forward and work together for the sustainable development of the cities in developing nations particularly by providing skills and efficient technologies for the improvement of water quality and wastewater treatment systems. For this, the progress of a systematic supported decision-making tool to allow investors and consumers to contribute to the development of sustainable water management methods and sewage treatment systems through bi- and multilateral investments. In addition, the active involvement of multi-stakeholders (citizens, local municipalities, industries, policy makers) with financial and non-financial institutions would help to create a “sustainable cities” in developing countries.
Implementation of partial melting with a water- and composition-dependent solidus temperature adapted to TTG formation
Authors: Rozel Antoine , Mojzsis Stephen , Guitreau Martin , Manjón Cabeza Córdoba Antonio , Ballmer Maxim , Tackley Paul
Published: March 2020

More and more convection codes now consider the apparition of melt when the temperature of the mantle exceeds a considered solidus temperature. How melt is treated when it appears varies a lot from one code to another. The convection code StagYY has been using an implementation in which molten eclogite is produced out of melting of mixed mantle. The melt is then teleported above ("erupted") or below ("intruded") the basaltic crust. In a recent study by Jain et al. 2019, we have shown that it is possible to also self-consistently generate continental crust (so-called TTG rocks) if the basaltic crust is entrained in the mantle and remolten. In nature, this only happens if a lot of water is present in the recycled basalt so a numerical treatment of water is necessary.

In this poster, we discuss the details of a new implementation of melting in which each cell of the convection domain is divided in several groups of different composition. Each group has a different solidus and liquidus temperature according to the composition and the water content. The solidus temperature is computed using an interpolation between composition and water concentration end members instead of using an extrapolation from the solidus temperature, as it is usually done. This ensures that TTGs form at a realistic melt fraction and provides a different view on how the continental crust of the early Earth might have formed.
The influence of Tibetan Plateau surface warming on climate extremes across South-East Asia
Authors: Talib Joshua , Taylor Christopher
Published: March 2020

With an average height greater than 4500m and an area covering approximately 2.5 million km2, the Tibetan Plateau (TP) plays a crucial role in determining the large-scale atmospheric circulation across South-East Asia. Substantial intraseasonal precipitation variability is observed across TP associated with the subtropical jet location and silk road pattern. A northward shift of the subtropical jet is associated with reduced precipitation over TP. Through analysis of weather station data and satellite observations, a diurnally-varying sensitivity of the land surface to intraseasonal precipitation variability is concluded. For example, a prolonged dry spell is associated with warmer ground temperatures and increased surface sensible heat flux. Using reanalyses the influence of anomalous surface conditions across TP, associated with intraseasonal precipitation variability, on the local and remote circulation is investigated.

During a dry spell increased surface sensible heat flux deepens the planetary boundary-layer and leads to the development of a localised heat low anomaly. In the upper-troposphere surface sensible heating forms an anticyclonic anomaly above TP which induces an upper-level Rossby-wave train. The induced Rossby-wave train is associated with an anomalous cyclonic circulation across central China and a westward extension of the west Pacific subtropical high. These circulation anomalies induced by TP surface warming are associated with climate extremes across South-East Asia including an increased risk of flash drought across central China and higher probabilities of extreme precipitation across southern China. The association between land-atmosphere interactions across TP and climate extremes in South-East Asia highlight the importance of land-atmosphere feedbacks in forecasting climate extremes.
Deposition of nanoplastics in high-altitude Alpine snow
Authors: Materic Dusan , Ludewig Elke , Cristescu Simona M. , Röckmann Thomas , Holzinger Rupert
Published: March 2020

Recent research discovered that airborne microplastics pollution can reach very remote areas. However, analysis of nanoplastics in environmental samples remains challenging, mostly due to technical and methodological issues. A new method for chemical characterisation of nanoplastics based on TD-PTR-MS has been recently introduced. The detection limit of <1ng allowed for the first time the analysis of nanoplastics deposited on the snow in the pristine Alps. In this work, we analysed daily samples of surface snow close to the Sonnblick Observatory, Austria (3106 m altitude) in the period from 2017-02-07 to 2017-03-19, using our new method. The results showed a positive detection for various types of nanoplastics, and the most common type found was Polyethylene terephthalate (PET). We will present our results on the to-date longest daily record of nanoplastics deposition in high altitude regions and further discuss optimisations of TD-PTR-MS method for nanoplastics detection and quantification.
Probing the characteristics of mush-magma transition: insights from laboratory experiments
Authors: Sgreva Nicolò Rubens , Davaille Anne , Kumagai Ichiro , Kurita Kei
Published: March 2020

The mush-magma transition (MMT) marks a profound change in rheological properties between two of the principal magmatic reservoirs that constitute a magmatic system. Mush behaves as a solid and its rheology is largely dominated by the deformation of the crystals network whereas magma is a liquid and has a rheology dominated by melt.

To better understand the solid-liquid transition in such crystal-rich systems, we present here an experimental study using mixtures of aqueous superabsorbent polymers (SAPs). SAPs are constituted of polymer grains that in water can swell up to 100 times and form gel grains whose size can be controlled by controlling the size of the initial powder. Particle fractions between 60% and 80% are easy to reach, making this system a promising analog of mush. The non-Newtonian rheology of the mixture of water and touching grains combines viscous, elastic and plastic aspects and can be characterized using the free-fall of spheres of different diameters and densities. 

We observe five different regimes of motion for the settling of a sphere: (1) A linear regime where the sphere has a rapid and linear fall and reaches a constant terminal velocity. (2) An irregular regime where the sphere’s velocity fluctuates around a constant value. (3) A stop&go regime where periods of no-motion and periods of irregular falls follow one another. (4) A slow fall regime where the sphere’s velocity progressively decreases in a logarithmic way. And (5) a no-motion regime when spheres are not buoyant enough to overcome the yield stress of the mixture or are too small compared to the grain size. So, the Yield number (ratio of the yield stress to the sphere buoyancy-induced stress), critical value Yc above which there is no motion decreases as the sphere to grain diameters ratio becomes smaller than 2. This enlarges the domain of conditions under which the mush strength will lead to the entrapment of the intruder. Moreover, the mixture structure strongly affects the path that a buoyant melt pocket can follow through the mush, and the time it spends motionless. The latter will increase the time available for reactions between melt and surrounding crystalline matrix.
A statistical analysis method estimating dust aerosol-ice cloud interactions using global circulation model and satellite data
Authors: Offenwanger Thomas , Beck Christoph , Popp Thomas , Hendricks Johannes , Righi Mattia
Published: March 2020

A statistical analysis method to quantify dust aerosol interactions with ice cloud properties using IASI satellite data has been developed and published by L. Klüser et al. 2017. Key components of analyzing cloud properties are their classification by aerosol load and their normalization in respect to the meteorological state using a Bayes-approach. Comparing histograms of cloud properties for different aerosol classes gives then insight in statistical changes of their distribution. Using the same method twice on IASI-IMARS satellite retrieval and EMAC-MADE3 global circulation model data yields valuable insights on changes in cloud forming and lifecycle behavior inflicted by dust aerosol pollution. Overcoming scale differences between observation and simulation data sets has been a major obstacle as they have evident impact on the analysis results. Therefore, a statistical downscaling method has been customized to EMAC-MADE3 model data that focuses on preservation of critical processes while still approximating fine-scale patterns below model resolution. Both statistical analysis results for model and satellite data show clear aerosol impact on cloud property distributions with varying magnitudes and demonstrate the necessity of downscaling. More detailed analysis conducted with an increased number of aerosol classes shows quantifiable trends in aerosol impact on cloud properties.
Use of Convolution Neural Networks and Object Based Image Analysis for Automated Rock Glacier Mapping
Authors: Robson Benjamin Aubrey , Bolch Tobias , MacDonell Shelley , Hölbling Daniel , Rastner Philip , Schaffer Nicole
Published: March 2020

Rock glaciers are an important, but often overlooked, component of the cryosphere and are one of the few visible manifestations of permafrost. In certain parts of the world, rock glaciers can contribute up to 30% of catchment streamflow. Remote sensing has permitted the creation of rock glacier inventories for large regions, however, due to the spectral similarity between rock glaciers and the surrounding material, the creation of such inventories is typically conducted based on manual interpretation of remote sensing data which is both time consuming and subjective. Here, we present a method that combines deep learning (convolutional neural networks or CNNs) and object-based image analysis (OBIA) into one workflow based on freely available Sentinel-2 imagery, Sentinel-1 interferometric coherence, and a Digital Elevation Model. CNNs work by identifying recurring patterns and textures and produce a heatmap where each pixel indicates the probability that it belongs to a rock glacier or not. By using OBIA we can segment the datasets and classify objects based on their heatmap value as well as morphological and spatial characteristics and convert the raw probability heatmap generated by the deeo learning into rock glacier polygons. We analysed two distinct catchments, the La Laguna catchment in the Chilean semi-arid Andes and the Poiqu catchment on the Tibetan Plateau. In total, our method mapped 72% of the rock glaciers across both catchments, although many of the individual rock glacier polygons contained false positives that are texturally similar, such as debris-flows, avalanche deposits, or fluvial material causing the user’s accuracy to be moderate (64-69%) even if the producer’s accuracy was higher (75%). We repeated our method on very-high resolution Pléiades satellite imagery (resampled to 2 m resolution) for a subset of the Poiqu catchment to ascertain what difference the image resolution makes. We found that working at a higher spatial resolution has little influence on the user’s accuracy (an increase of 3%) yet as smaller landforms were mapped, the producer’s accuracy rose by 13% to 88%. By running all the processing within an object-based analysis it was possible to both generate the deep learning heatmap and automate some of the post-processing through image segmentation and object reshaping. Given the difficulties in differentiating rock glaciers using image spectra, deep learning offers a feasible method for automated mapping of rock glaciers over large regional scales.
Thermobarometry of Jurassic and Early Cretaceous plutonic rocks from the Northern Andes: tracing magmatic and tectonic changes
Authors: Chavarria Luisa , Bustamante Camilo , Cardona Agustín , Restrepo Marcela
Published: March 2020

Plutonic rocks in magmatic arcs record variations in composition, thermal flux, and dynamics of subduction through time. In the northern Andes, arc magmatism of Jurassic age registers a complex history, including the fragmentation of Pangea at the end of the Triassic as well as the beginning of a new subduction zone in the Jurassic located at the western margin of South America. Two contrasting models have been proposed by previous researches to explain the evolution of this arc: i) continuous subduction with a slab-roll back that produced a crustal thinning and ii) oblique subduction associated with a crustal thickening.

We characterized the emplacement conditions and crustal thickness variations of the Jurassic and Early Cretaceous arc in the northern Andes from 170 to 130 Ma using a combination of thermobarometers and trace element signatures and reviewed the previously suggested evolution models. The zircon and apatite saturation temperatures indicate that the intermediate magma became Zr and P2O5 oversaturated at 695-739 °C and 849-909 °C, respectively. Pressures obtained with the Al-in-hornblende barometer shows that the magma emplacement pressures varied from 1.2 to 7.1 kbar, with two distinct trends. A low-pressure trend (<2 kbar) related to different stock size bodies emplaced through the arc formation and a high-pressure trend (>5 kbar), which is restricted to the southern segment of the arc at the end of the Jurassic. Low Sm/Yb and Dy/Yb ratios show that the magma interacted with an amphibole-rich crust, implying that the Northern Andes was characterized by a thin crust during the Jurassic.

The shallow emplacement pressures and thin crust suggest that the Jurassic magmatic arc record a predominant extensional tectonic style that could be linked with the Pangea breakup and the beginning of the arc magmatism. However, the younger magmatic pulses are characterized by higher emplacement pressures associated with an increase in crustal thickness during convergence. Such variation indicates that the Jurassic magmatism in the Northern Andes experienced significant changes in their tectonic controls and not a single dominant mechanism, as has been proposed.