bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Synergistic Climatic Effects of Covarying Major Mountain Range Topographies
Authors: Mutz Sebastian G. , Ehlers Todd A.
Published: March 2020

The interpretation of Earth surface archives often requires consideration of distant off-site events. One such event is the surface uplift of Earth’s major mountain ranges, which affects climate and the Earth’s surface globally. In this study, the individual and synergistic climatic effects of topographic changes in major mountain ranges are explored with a series of General Circulation Model (GCM) experiments and analyses of atmospheric teleconnections. The GCM experiments are forced with different topographic scenarios for Himalaya-Tibet (TBT) and the Andes (ADS), while environmental boundary conditions are kept constant. The topographic scenarios are constructed by successively lowering modern topography to 0% of its modern height in increments of 25%. This results in a total of 5 topographic scenarios for TBT (tbt100, tbt075, tbt050, tbt025, tbt000) and ADS (ads100, ads075, ads050, ads025, ads000). TBT scenarios are then nested in ADS scenarios, resulting in a total of 25 experiments with unique topographic settings. The climate for each of those 25 scenarios is simulated with the GCM ECHAM5-wiso. We then explore possible synergies and distant impacts of topographic changes by testing the hypothesis that varying ADS has no effect on simulated climate conditions in the TBT region (c_tbt) and vice versa. This can be expressed as the null hypothesis c_tbt(ads100) = c_tbt(ads075) = c_tbt(ads050) = c_tbt(ads025) = c_tbt(ads000) for each of the 5 TBT scenarios, and vice versa. We conduct Kruskal-Wallis tests for a total of 10 treatment sets to address these hypotheses. The results suggest that ADS climate is mostly independent of TBT topography changes, whereas TBT climate is sensitive to ADS topography changes when TBT topography is high, but insensitive when TBT topography is strongly reduced. Analyses of atmospheric pressure fields suggest that TBT height acts as a control on cross-equatorial atmospheric transport and modifies the impact of ADS topography on northern hemisphere climate. These results dictate a more careful consideration of global (off-site) conditions in the interpretation of Earth surface records.
A hydro-thermo-haline numerical approach of the groundwater flow to explain the extreme Li-enrichment in the Salar de Atacama (NE Chile)
Authors: Marazuela Miguel Angel , Ayora Carlos , Vázquez Suñé Enric , Olivella Pastallé Sebastià , García Gil Alejandro
Published: March 2020

Salt flats (salars) are endorheic hydrogeological systems associated with arid to hyperarid climates. The brines of salt flats account the 80 % of the world’s reserves of Li highly demanded by modern industry. About 40 % of the worldwide Li is extracted from the brine that fills the pores and cavities of the Salar de Atacama. However, the origin of the extreme Li-enrichment of these brines is still unknown.

The thick accumulation of salts and brines in salt flats results from the groundwater discharge (phreatic evaporation) near the land surface for thousands to millions of years. The strong evaporation contributes the enrichment in major cations and anions as well as other rare elements (e.g. Li, B, Ba, Sr, Br, I and F) which are very attractive for mining exploitation. However, only evaporation cannot explain by itself the extreme concentrations of some of these elements and the strong decoupling between the most evaporated brines and the most Li-enriched brines in the Salar de Atacama. Several hypotheses have been proposed to explain the extreme Li-enrichment of the salt flat brines: (a) concentrated brines leaking down from salt flats located in the Andean Plateau, (b) leaching of hypothetical ancient salt flats buried among volcanic rocks, and (c) rising of hydrothermal brines from deep reservoirs through faults. However, none of them has been able probed neither validated by a numerical model till the date.

The objective of this work is to discuss the feasibility of the different hypotheses proposed until now to explain the formation of the world's largest lithium reserve. To achieve this objective, two sets of numerical simulations of a 2D vertical cross-section of the entire Salar de Atacama basin are carried out to define (1) the origin and evolution of a salt flat and how climate cycles can affect the location of the most Li-concentrated brines by evaporation and (2) the establishment of the hydro-thermo-haline circulation of a mature salt flat basin.
Trends in total heat content in a very long climate change simulation
Authors: Stendel Martin
Published: March 2020

The equivalent potential temperature Θe is a useful measure of the total heat content in the atmosphere, as it is conserved during both dry adiabatic and wet adiabatic processes. It is defined as letting an air parcel expand pseudo-adiabatically until all the water vapour has condensed, release and precipitate all its latent heat and compress it dry-adiabatically to the standard pressure of 1000 hPa.

Changes in surface or air temperature can thus be related to changes in humidity. For example, the relative contributions of temperature and humidity changes in tropical cyclones can be addressed, Arctic amplification due to the fact that saturation mixing ratio follows an exponential curve with temperature can be investigated, and by considering Θe in different vertical levels, an assessment of changes in convective stability can be made.

We have conducted a very long climate simulation with a global model interactively coupled to a Greenland ice sheet component. An extended RCP8.5 scenario is applied, where emissions of greenhouse gases continue to increase and then eventually level out around 2250. The model is then run for another 1000 years. With such an extreme forcing, all Arctic sea ice has completely disappeared, and a large part of the Greenland Ice Sheet has melted at the end of the simulation.

We examine changes in the total heat content based on observations and model data for past and present as well as for future climate. Daily data, allowing the identification of individual weather systems will be discussed for time slices with a seasonally and later a totally ice-free Arctic.
Standard-Phase-height measurements over Europe during 60 years of measurements – Long-term variability and trends of the mesosphere
Authors: Peters Dieter H.W. , Entzian Günter
Published: March 2020

Beginning with 1959 that means over more than 60 years, ﬁeld strength measurements of the broadcasting station, Allouis (Central France), have been carried out at Kühlungsborn (54° N, 12° E, Mecklenburg, Northern Germany. These so-called indirect phase-height measurements of low frequency radio waves (here with a frequency of 162 kHz) are used to examine the long-term evolution and trends of the mesosphere over Europe. The advantages of the method are the low costs and the simplicity of operation. The extended reanalyzed fifth release of standard-phase height (SPH) are presented.

The SPH-series are anti-correlated to the solar cycle as known because stronger photo-ionization is linked with higher number of electrons, which reduces the SPH. The anti-correlation between SPH and proxies of solar cycle are well established. Furthermore the statistical analysis of the SPH-series shows a signiﬁcant overall trend in the order of hundred meters per decade induced by a shrinking stratosphere due to global warming. Strong intra-decadal variability is related to QBO like and ENSO like variability. The derived thickness temperature of the mesosphere decreased statistically significant over the period 1959-2019 after pre-whitening with summer means of solar sun spot numbers. The trend value is in the order of about -1 K/ decade if the stratopause trend is excluded. The amount of linear regression is weaker, -0.8 K/ decade for the period of 1963-1985 (2 SCs), but stronger, about -1.6 K/ decade during 1995-2016 (last 2 SCs).
Four Decades of Lithosphere and Solid Earth Research - ILP's Role as Stimulus
Authors: Cloetingh Sierd A.P.L. , Green Alan G. , Negendank Jörg F.W. , Oberhänsli Roland , Rudloff Alexander , Scheck-Wenderoth Magdalena , Thybo Hans
Published: March 2020

The International Lithosphere Program (ILP) was established in 1980 as the Inter-Union Commission on the Lithosphere (ICL) by the International Council for Science (ICSU), following a request from the International Union of Geodesy and Geophysics (IUGG) and the International Union of Geological Sciences (IUGS). In 2005 ICSU transferred its sponsorship to IUGG and IUGS.

The ILP focusses on the nature, dynamics, origin, and evolution of the lithosphere, with special attention to the continents and their margins. Targeting these goals through international and interdisciplinary collaboration, ILP established several task forces and coordinating committees to pursue specific research objectives. Topics always follow one of the four ILP themes: global change, contemporary dynamics and deep processes, continental lithosphere, and ocean lithosphere. ILP’s funding is limited to five year periods and just understood as seed money.

In the last four decades ILP was involved in the composition and set up of a number of worldwide leading light house projects: The GSHAP (Global Seismic Hazard Map), the ICDP (International Continental Drilling Project), the WSM (World Stress Map Project), the TOPO-Europe project and its follow up initiatives TOPO-Asia, TOPO Iberia – just to name a few. Currently ILP supports new initiatives on digitalization.

With its Flinn-Hart Award (until 2007 Hart Award), honouring outstanding young scientists for contributions in the field of solid Earth sciences, ILP motivated and promoted a generation of early career scientists. The new Evgueni Burov Medal from ILP, established in 2018, pays tribute to an outstanding researcher in solid Earth sciences and recognizes pioneering contributions by mid-career scientists.
Cyclo and chemostratigraphic characteristics of the Middle Silurian in Gotland, Sweden
Authors: Arts Michiel , Cramer Bradley , Calner Mikael , Rasmussen Christian , Bancroft Alyssa , Oborny Stephan , Hartke Emma , Biebesheimer Ellie , Da Silva Anne-Christine
Published: March 2020

The cumulative work of geoscientists over the past decades has shown that the Silurian Period which was once thought as warm and climatically stable time interval is in fact punctuated by numerous paleoenvironmental perturbations or events. These Silurian events follow a similar pattern where a minor extinction event precedes a substantial carbon isotope excursion. Many theories have been brought forward to explain these events ranging from glaciations, to changes in precipitations patterns, ocean currents and ocean anoxia. Constraints on the duration and timing of these extinction events and subsequent positive carbon isotope excursions are weak, which hampers a full understanding of the processes at play.

The data from the Altajme core from Gotland, Sweden provides us with a unique opportunity to look at two of these climatic perturbations during the Silurian. The Altajme core spans both the Sheinwoodian Ireviken event and the Homerian Mulde event. The Altajme core dataset includes a litholog, high-resolution δ13C data, correlated bentonites with U-Pb dates and a high-resolution XRF core scan: important data required for and integrated stratigraphic study. The U-Pb-dated bentonites give us age constraints. The δ13C data in combination with the high resolution XRF scan gives us insights into the changes in the ocean before during and after the events, while the XRF is also used to build cyclostratigraphic age constraints for the events and for the whole core. This stratigraphic study will provide us with a palaeoclimatological insights to explain these two events and provide us with a cyclostratigraphy based age model for the Middle Silurian.
Spatial conditional extremes via the Gibbs sampler.
Authors: Casey Adrian , Papastathopoulos Ioannis
Published: March 2020

Spatial conditional extremes via the Gibbs sampler.

Adrian Casey, University of Edinburgh

January 14, 2020

Conditional extreme value theory has been successfully applied to spatial extremes problems. In this statistical method, data from observation sites are modelled as appropriate asymptotic characterisations of random vectors X, conditioned on one of their components being extreme. The method is generic and applies to a broad range of dependence structures including asymptotic dependence and asymptotic independence. However, one issue that affects the conditional extremes method is the necessity to model and fit a multi-dimensional residual distribution; this can be challenging in spatial problems with a large number of sites.

We describe early-stage work that takes a local approach to spatial extremes; this approach explores lower dimensional structures that are based on asymptotic representations of Markov random fields. The main element of this new method is a model for the behaviour of a random component Xi  given that its nearest neighbours exceed a sufficiently large threshold. When combined with a model for the case where the neighbours are below this threshold, a Gibbs sampling scheme serves to induce a model for the full conditional extremes distribution by taking repeated samples from these local (univariate) distributions.

The new method is demonstrated on a data set of significant wave heights from the North Sea basin. Markov chain Monte-Carlo diagnostics and goodness-of-fit tests illustrate the performance of the method. The potential for extrapolation into the outer reaches of the conditional extreme tails is then examined.

Joint work with Ioannis Papastathopoulos.
EnvironMICADAS C-14 AMS Gas ion source performance and its applications at HEKAL Laboratory, Debrecen, Hungary
Authors: Molnár Mihály , Janovics Róbert , Major István , Hubay Katalin , Buró Botond , Varga Tamás , Kertész Titanilla , Gergely Virág , Veres Mihaly , Jull A.J. Timothy
Published: March 2020

A coupled accelerator mass spectrometer - gas interface system successfully has been operating at the Hertelendi Laboratory of Environmental Studies, Debrecen, Hungary since 2013. Over the last 6 years more than 500 gas targets were measured below 100 µg carbon content for carbon isotopic composition. The system was tested with blanks, OxII, IAEA-C1, IAEA-C2 and IAEA-C7 standards. The performance of our instrumentation shows good agreement with other published gas-interface system data and also shows a quite good agreement with the nominal value of international standard samples.  There is a measurable but quite small memory effect after modern samples, but this does not significantly affect the final results. Typical ion currents at the low energy side were between 10-15 µA with a 5% CO2 in He mixing ratio. The relative errors average ±6% for samples greater than or equal to 10 µgC sample with mean count rates of 300 counts per microgram C for OxII. The blank is comparable with other systems, which is 0.0050 ± 0.0018 F14C or 34000-47000 yr BP, which allows for the routine measurement of both of small environmental and archeological samples.

The research was supported by the European Union and the State of Hungary, co-financed by the European Regional Development Fund in the project of GINOP-2.3.2-15-2016- 00009 “ICER”. This work was carried out in the frame of the János Bolyai Research Scholarship (Mihály Molnár) of the Hungarian Academy of Sciences
Crustal structure of the Basque-Cantabrian Zone (N Spain) from seismic noise and receiver functions
Authors: Olivar-Castaño Andrés , Pilz Marco , Pedreira David , Pulgar Javier A. , Díaz-González Alba , González-Cortina Juan Manuel
Published: March 2020

The Basque-Cantabrian Zone was one of the most subsident areas between the European plate and the Iberian sub-plate during the Mesozoic rifting process that gave birth to the Bay of Biscay. Since the latest Cretaceous and during the Cenozoic, a change to a contractional setting driven by the northward drift of the African Plate made this hyperextended rift basin to be inverted and incorporated into the Pyrenean-Cantabrian mountain belt. The resulting crustal structure shows a high complexity, as evidenced by the many existing geophysical observations pointing to the presence of intracrustal high-velocity bodies, deep transfer structures, and sharply-varying Moho depths across the area.

In this work, we use data provided by the dense SISCAN and MISTERIOS seismic networks, deployed in the region between 2014 and 2018, to obtain a detailed 3D shear-wave velocity model. We use the continuous recordings to compute seismic noise cross-correlation functions, from which we extract surface wave dispersion measurements. We use these measurements to obtain a set of phase velocity maps, and then perform a non-linear inversion at regularly spaced locations for the 1D shear-wave velocity structure. In the non-linear inversion, the forward modeling accounts for the presence of higher modes of surface waves, which have been shown to be more sensitive to velocity decreases with depth than the fundamental model. In order to better constrain the deeper layers of the model, we complement the seismic noise observations with an analysis of teleseismic receiver functions, which allows us to better constrain the depths of the major crustal discontinuities. Our results agree with previous geophysical studies, but significantly improve the availability of high-resolution information in the Basque-Cantabrian Zone.
ENSO continuum and its impacts on worldwide precipitation: Observation vs. CMIP5/6
Authors: Dieppois Bastien , Eden Jonathan , Monerie Paul-Arthur , Pohl Benjamin , Crétat Julien , Chun Kwok Pan
Published: March 2020

It is now widely recognized that El Nino-Southern Oscillation (ENSO) occurs in more than one form, e.g. eastern and central Pacific ENSO. Given that these various ENSO flavours may contribute to climate variability and trends in different ways, this study presents a framework that treats ENSO as a continuum to examine its impact on precipitation, and to evaluate the performance of the last two generations of global climate models (GCMs): CMIP5 and CMIP6.

Uncertainties in the location and intensity of observed El Nino and La Nina events are assessed in various observational and satellite-derived products (ERSSTv5, COBESSTv2, HadSST1 and OISSTv2). The probability distributions of El Nino and La Nina event locations, and intensities, slightly differ from one observational data set to another. For instance, La Nina events are more intense and more likely to occur in the central Pacific using COBESSTv2. All these products also depict consistent decadal variations in the location and intensity of ENSO events: i) central Pacific ENSO events were more likely in the 1940/50s and from the 1980s; ii) eastern Pacific ENSO events were more likely in the 1910/20s and 1960/70s; iii) La Nina events have become more intense during the 20th and early 21st centuries.

These fluctuations in ENSO location and intensity are found to impact precipitation consistently across diverse global precipitation products (CRUv4.03, GPCCv8 and UDELv5.01). Over southern Africa, for instance, more intense eastern (central) Pacific El Nino events are found to favour drought conditions over northern (southern) regions during austral summer. By contrast, over the same regions, more intense La Nina events favours wet conditions, while the location of these events has little effect on precipitation. Over West Africa, ENSO locations favour a zonal (E-W) rainfall gradient in precipitation during boreal summer, while changes in ENSO intensity modulate the strength of the meridional (N-S) rainfall gradient.

Using both historical and pi-Control runs, we demonstrate that most CMIP5 and CMIP6 models favour either eastern or central Pacific ENSO events, but very few models are able to capture the full observed ENSO continuum. Regarding ENSO impacts on worldwide precipitation, contrasted results appear in most models.
Permeability of serpentinites at high PT: towards fluid flow determination in subduction zones
Authors: Eberhard Lisa , Eichheimer Philipp , Fujita Wakana , Thielmann Marcel , Nakamura Michihiko , Golabek Gregor J. , Frost Daniel J.
Published: March 2020

The process of dehydration in subduction zones is important for (i) element recycling, (ii) hydration of the mantle wedge, as well as (iii) melting processes related to arc volcanism. Additionally, the release of fluids is also proposed to be related to the origin of deep earthquakes. The transport of fluids from the slab into the mantle requires a sufficiently high permeability. Due to shear deformation in subduction zones a strong foliation will be developed by preferred orientation of serpentinite minerals, which might influence the permeability. Measurements of permeability up to 100 MPa indeed showed that the foliation yields a strong anisotropy in serpentinites. The permeability parallel to the foliation is one order of magnitude higher than in the perpendicular direction.

Here we present a method to estimate the fluid flux in serpentinites at mantle conditions combining laboratory experiments, X-ray CT scans and numerical modelling. For this purpose, we performed HP-multi-anvil experiments at temperatures of 500 °C to 700 °C and pressure up to 2.5 GPa. As starting material we used a natural antigorite sample showing a strong foliation. A cylindrical drill core is placed into an MgO sleeve. The MgO is hydrated to brucite at the PT conditions at which serpentine is still stable, i.e. serpentine partially dehydrates and brucite is formed as the released fluid moves into the MgO sleeve. After the experiment the location and proportion of brucite formed allows the preferred fluid flux to be determined. The formation of 5 times less volume per unit area of brucite in the direction perpendicular to the foliation indeed indicates a preferred fluid flow parallel to the preferred orientation.

In a second step we employ CT scans to obtain data on the pore space of the samples. Finally, using numerical methods, we determine both the porosity as well as the permeability of the recovered samples. Combined, these methods can be used to obtain a model of fluid flow in subduction zones.
Agricultural water consumption and crop prices
Authors: Falsetti Benedetta , Vallino Elena , Ridolfi Luca , Laio Francesco
Published: March 2020

Most human activities depend on water. Agriculture alone consumes 70% of all freshwater withdrawals worldwide.  In cases when such withdrawal overcome sustainability levels, water scarcity represents a growing threat to food security. In this framework, there has been an enduring debate on the opportunity of assigning an economic value to water. Some studies argue that water resources would be more efficiently allocated if they had a price that reflects their scarcity and that a pricing policy would also provide incentives for more sustainable consumption. Building on these considerations, in this work we investigate whether the water consumption in agricultural production is reflected in crop prices. 

In this research, we focus specifically on the production of agricultural primary goods to understand whether water consumption is taken into consideration in the prices associated with these products on the global market. We consider the water component also in terms of water availability per capita at the country level (Falkenmark Water Stress Indicator). Aware of the fact that water and land are usually regarded as a single entity, we analyze if the water, isolated from this relation, still has an impact.

We select twelve representative crops analyzing their farm gate prices from 1991 to 2016, collecting data regarding 162 countries in total. We identify two different behaviors: staple crops (e.g. wheat, maize, soybeans, and potatoes) tend to incorporate in their prices the amount of water employed during the cultivation process. Differently, cash crops (e.g. coffee, cocoa beans, tea, vanilla), which are not crucial in human diets and mainly produced for exportation purposes, show a weaker relationship between water footprint and prices on the global market. These variations may be ascribable to specific market dynamics related to the two product groups. While there could be different elements influencing the behavior of these two macro-categories of crops, it is important to understand how water is related to crop prices to purse more efficient practices in water allocation and governance management, improving environmental sustainability in this field.
Projecting future vegetation change for northeast China using CMIP6
Authors: Yuan Wei , Wu Shuang-ye , Hou Shugui
Published: March 2020

This study aims to establish future vegetation changes in the east and central of northern China (ECNC), an ecologically sensitive region in the transition zonal from humid monsoonal to arid continental climate. The region has experienced significant greening in the past several decades. However, few studies exist on how vegetation will change with future climate change, and great uncertainties exist due to complex, and often spatially non-stationary, relationships between vegetation and climate. In this study, we first used historical NDVI and climate data to model this spatially variable relationship with Geographically Weighted Logit Regression. We found that temperature and precipitation could explain, on average, 43% of NDVI variance, and they could be used to model NDVI fairly well. We then establish future climate change using the output of 11 CMIP6 models for the medium (SSP245) and high (SSP585) emission scenarios for the mid-century (2041-2070) and late-century (2071-2100). The results show that for this region, both temperature and precipitation will increase under both scenarios. By late-century under SSP585, precipitation is projected to increase by 25.12% and temperature is projected to increase 5.87oC in ECNC. Finally, we used future climate conditions as input for the regression models to project future vegetation (indicated by NDVI). We found that NDVI will increase under climate change. By mid-century, the average NDVI in ECNC will increase by 0.024 and 0.021 under SSP245 and SSP585. By late-century, it will increase by 0.016 and 0.006 under SSP245 and SSP585 respectively. Although NDVI is projected to increase, the magnitude of increase is likely to diminish with higher emission scenarios, possibly due to the benefit of precipitation increase being gradually encroached by the detrimental effects of temperature increase. Moreover, despite the overall NDVI increase, the area likely to suffer vegetation degradation will also expands, particularly in the western part of ECNC. With higher emissions and later into the century, region with low NDVI is likely to shift and/or expand north-forward. Our results could provide important information on possible vegetation changes, which could help to develop effective management strategies to ensure ecological and economic sustainability in the future.
Source-structure trade-offs in noise correlation functions in 3-D
Authors: Sager Korbinian , Boehm Christian , Tsai Victor
Published: March 2020

Noise correlation functions are shaped by both noise sources and Earth structure. The extraction of information is thus inevitably affected by source-structure trade-offs. Resorting to the principle of Green’s function retrieval deceptively renders the distribution of ambient noise sources unimportant and existing trade-offs are typically ignored. In our approach, we consider correlation functions as self-consistent observables. We account for arbitrary noise source distributions in both space and frequency, and for the complete seismic wave propagation physics in 3-D heterogeneous and attenuating media. We are therefore not only able to minimize the detrimental effect of a wrong (homogeneous) source distribution on 3D Earth structure by including it as an inversion parameter, but also to quantify underlying trade-offs.

The forward problem of modeling correlation functions and the computation of sensitivity kernels for noise sources and Earth structure are implemented based on the spectral-element solver Salvus. We extend the framework with the evaluation of second derivatives in terms of Hessian-vector products. In the context of probabilistic inverse problems, the inverse Hessian matrix in the vicinity of an optimal model with vanishing first derivatives and under the assumption of Gaussian statistics can be interpreted as an approximation of the posterior covariance matrix. The Hessian matrix therefore contains all the information on resolution and trade-offs that we are trying to retrieve. We investigate the geometry of trade-offs and the effect of the measurement type. In addition, since we only invert for sources at the surface of the Earth, we study how potential scatterers at depth are mapped into the inferred source distribution.

A profound understanding of the physics behind correlation functions and the quantification of trade-offs is essential for full waveform ambient noise inversion that aims to exploit waveform details for the benefit of improved resolution compared to traditional ambient noise tomography.
Coupling the MULTI-VP model with EUHFORIA
Authors: Samara Evangelia , Magdalenic Jasmina , Pinto Rui F. , Jercic Veronika , Scolini Camilla , Rodriguez Luciano , Poedts Stefaan
Published: March 2020

The EUropean Heliospheric FORecasting Information Asset (EUHFORIA) is a new 3D magnetohydrodynamic (MHD) space weather prediction tool (Pomoell and Poedts, 2018). EUHFORIA models solar wind and coronal mass ejections (CMEs) all the way from the Sun to 2 AU. It consists of two different domains; the coronal part, which extends from the solar surface to 0.1 AU and the heliospheric part, which covers the spatial domain from 0.1 AU onwards. For the reconstruction of the global solar corona, the empirical Wang-Sheeley-Arge (WSA, Arge, 2003) model is currently used, in combination with the potential field source surface (PFSS) model and the Schatten current sheet (SCS) model, in order to reconstruct the magnetic field up to 0.1 AU and produce the plasma boundary conditions required by the 3D MHD heliospheric part to initiate. In the framework of the ongoing validation of the solar wind modeling with EUHFORIA, we implemented and tested a different coronal model, the so-called MULTI-VP model (Pinto and Rouillard, 2017). First results and comparisons of EUHFORIA modeled output at Earth produced by employing the WSA and MULTI-VP coronal models, will be presented.
Numerical simulation of asthenospheric flow around cratonic keels
Authors: Santos Edgar , Sacek Victor
Published: March 2020

In this work, we studied the mantle flow around cratonic keels using numerical models to simulate the thermochemical convection in the terrestrial mantle taking into account the relative displacement between the lithosphere and asthenosphere. The numerical simulations were performed using the finite element code developed by Sacek (2017) to solve the Stokes Flow for an incompressible Newtonian fluid. Several synthetic models in 2D and 3D were constructed considering different keel geometries and different regimes of relative displacement between the lithosphere and asthenosphere. In the present numerical experiments, we adopted a rheology in which the viscosity of the mantle is controlled by temperature, pressure and composition, assuming that the cratonic keel is compositionally more viscous than the surrounding asthenosphere, using a factor f to rescale the lithospheric viscosity compared to the asthenospheric one. We tested different f values, reference viscosity for the asthenosphere, and relative velocity between the lithosphere and the base of the upper mantle, quantifying the amount of deformation of the cratonic keel in each scenario. In general, we conclude that for a relatively low compositional factor (f < 20), the lithospheric keel can be significantly deformed in a time interval of few tens of million years when the lithosphere is moving horizontally relative to the base of the upper mantle, does not preserving its initial geometry. The synthetic models can be helpful for a better understanding of the interaction in the lithosphere-asthenosphere interface such as the deformation and flow patterns in the mantle around the keels, the rate of erosion of the root of the continental lithosphere due to the convection in the upper mantle and how it affects the thermal flow to the surface.

Sacek, V. (2017). Post-rift influence of small-scale convection on the landscape evolution at divergent continental margins. Earth and Planetary Science Letters, 459, 48-57.
Two leading modes of wintertime atmospheric circulation drive the recent warm Arctic-cold Eurasia temperature pattern
Authors: Ye kunhui , Messori Gabriele
Published: March 2020

The wintertime warm Arctic-cold Eurasia (WACE) temperature trend during 1990-2010 was characterized by accelerating warming in the Arctic region, cooling in Eurasia and accelerating autumn/winter Arctic sea ice loss. We identify two atmospheric circulation modes over the North Atlantic-Northern Eurasian sector which displayed strong upward trends over the same period and can explain a large part of the observed decadal WACE pattern. Both modes bear a close resemblance to well-known teleconnection patterns and are relatively independent from anomalies in Arctic sea-ice cover. The first mode (PC1) captures the recent negative trends in the North Atlantic Oscillation and increased Greenland blocking frequency while the second mode (PC2) is reminiscent of a Rossby wave train and reflects an increased blocking frequency over the Urals and North Asia. We find that the loss in the Arctic sea ice and the upward trends in the PC1/PC2 together account for most of the decadal Arctic warming trend (>80%). However, the decadal Eurasian cooling trends may be primarily ascribed to the two circulation modes alone: all of the cooling in Siberia is contributed to by the PC1, and 65% of the cooling in East Asia by their combination (the contribution by PC2 doubles that by PC1). Enhanced intraseasonal activity of the two circulation modes increases blocking frequencies over Greenland, the Ural region and North Asia, which drive anomalous moisture/heat flux towards the Arctic and alter the downward longwave radiation. It weakens warm advection and enhances advection of Arctic cold airmass towards Eurasia.
The improvements to the numerical model of South China Sea Ocean Circulations
Authors: Zhu Xueming , Wang Hui , Zu Ziqing
Published: March 2020

The South China Sea (SCS) ocean circulations numerical model has been build up based on ROMS with high horizontal resolution. It had been operated in NMEFC to provide daily updated the hydrodynamic forecasting in SCS for the future 5 days since 2013, and named as the SCS operational Oceanography Forecasting System (SCSOFS). Recently, a few systematic optimizations have been carried out to the configuration of the physical model to improve SCSOFS forecast skill. For example, the differential schemes of horizontal and vertical advection of tracers are changed from 4th-order centered to 4th-ordered Akima, the schemes of horizontal mixing of tracers are changed from along epineutral surfaces to along geopotential surfaces, in order to correct for the spurious diapycnal diffusion of the advection operator in terrain-following coordinates, which could cause anomaly temperature increasing about 1 centigrade in deep layer. The method of sea surface atmospheric forcing is changed from direct forcing to bulk formula, by introducing the negative feedback effects between ocean and atmosphere, in order to improve forecast skill of sea surface temperature.
Back-arc extension dated from natural time markers across the Western Tyrrhenian Basin
Authors: Gaullier Virginie , Lymer Gaël , Chanier Frank , Maillard Agnès , Thinon Isabelle , Sage Françoise
Published: March 2020

The rifting of the Eastern Sardinian margin is considered to have occurred during the Neogene, by back-arc extension related to the eastward migration of the Apennine subduction system, leading to the development of the Tyrrhenian Basin, Western Mediterranean Sea. The locus of the extension during the rifting is interpreted to have occurred first in the East-Sardinia Basin (proximal margin), and then in the Cornaglia Terrace (distal margin). However, the dynamics of the Western Tyrrhenian Basin during the rifting is still largely undated, and the kinematics of the development of the different domains of the Eastern Sardinian margin remains poorly understood. This is due to the sparsity of dated rock samples within the basin, mainly recovered locally during ODP Leg 103, and because the timing of activity of the structures of the basin has been addressed so far using regional data, whose resolution is insufficient to observe the timing of the extension at the scale of a fault plane.

In this study, we use a 2400 km-long high-resolution seismic-reflection dataset acquired along the Eastern Sardinian margin during the “METYSS” research cruises in 2009 and 2011, and specifically designed to observe the block-bounding faults and the syn-rift and post-rift units. We interpret the syn-tectonic markers of the crustal deformation across the Eastern Sardinian margin, and we use the seismic markers of the Messinian Salinity Crisis (MSC) that provide exceptional and accurate natural time markers, to estimate the age of faults development and understand their evolution within the Western Tyrrhenian Basin.

Our observations demonstrate that the rifting was polyphased across the Western Tyrrhenian Basin, and that syn-rift extension was active on the proximal margin long before the MSC, whereas the distal Cornaglia Terrace developed only a short time before the MSC. Surprisingly, our interpretations also evidence significant post-rift reactivation of some structures of the Eastern Sardinian margin. These reactivations, formerly considered to be very minor or absent in the Western Tyrrhenian Basin, started in the Pliocene and occurred up to very-recent times along local fault-planes, as shown by the deformation of the shallowest Pleistocene layers and the seafloor.

Our results permit to precise the timing of the syn-rift and post-rift evolution of the Eastern Sardinian margin. Given the rarity of natural time makers in offshore sedimentary basins to address the dynamics of basins development, we expect our results to provide useful comparisons to study the kinematics of extension at other back-arc basins worldwide.
Plastic waste detection assisted by artifical intelligence
Authors: Gnann Nina , Garaba Shungu , Zielinski Oliver
Published: March 2020

 Plastic pollution has a big impact on living organisms. At the same time, plastics are everywhere in our daily life. For example, plastic is used in packaging, construction of buildings, cars, electronics, agriculture and many other fields. In fact, plastic production has been increasing rapidly since the 1950s. However, plastic waste management strategies have not adapted accordingly to these rising amounts, which end up in the blue and green planet. Unfortunately, for developing nations it is even more complicated and strategies are still developing. Here we investigate the possibilities of plastic waste detection in Cambodia focusing on cities, rivers and coastal areas. Very fine geo-spatial resolution Red-Green-Blue (RGB) drone imagery was captured over regions of interest in Phnom Penh, Sihanoukville and Siem Reap. To this date, techniques of detecting plastic litter are based on RGB imagery analyses, generating descriptors such as colour, shape, size and form. However, we believe by adding infrared wavebands additional descriptors, such as polymer composition or type can be retrieved for improved classification of plastic litter. Furthermore, remote sensing technologies will be merged with object-based deep learning methodologies to enhance identification of plastic waste items, thus creating a robust learning system. Due to the size and complexity of this problem, automated detection, tracking, characterization and quantification of plastic pollution is a key aspect to improve waste management strategies. We therefore explore multispectral band combinations relevant to the detection of plastic waste and operational approaches in imagery processing. This work will contribute towards algorithm development for analysis of video datasets enhancing future near real-time detection of plastic litter. Eventually, this scientific evidence-based tool can be utilized by stakeholders, policymakers and citizens.
Parametric Surfaced-Based Geological Reservoir Representation: A Computer Graphics Tool for Improved Decision Making in Immersive Environments
Authors: Moulaeifard Seyyedmohammad , Wellmann Florian
Published: March 2020

Uncertainties are an inherent part of geological interpretation and immersive rendering has the potential to play a key role in gaining better insights. However, most 3D geological models have a limited possibility of manual, fast and smooth modification in order to make better decisions and interpretations. Here we present examples of parametric surface representations which use control points as a possibility to bring interactivity to geological modelling in immersive frameworks.

In fact, using 2D surfaces of 3D solid objects is a typical representation of 3D models. Two of the major ways for surface representation in computer graphics are implicit representations and parametric surface representations. Parametric surface representations, unlike implicit representations, are based on control points. Manipulating these control points makes it easy and intuitive to modify geological models smoothly and fast, with a potential to more interactive decision-making.

We present two different examples of parametric surface approaches; Spline Surfaces and Subdivision Surfaces. Spline surfaces, e.g. Bezier or NURBS surfaces, are a popular and common standard for CAD (Computer-Aided Design). Also, these surfaces are on the basis of parametric- based curves and a set of weighted control points. Subdivision Surfaces define smooth surfaces after a series of refinement which can be controlled by control points. Subdivision surfaces are not only a popular method for making free form models but also a common tool in animation, computer games and entertainment industry.

Recently, research has been done based on using spline surfaces to model diverse geological structures and reservoirs. Similar to applications in computer graphics, using these methods in geological modelling can have specific considerations. Model refinement (e.g. adding new control points) and the requirement of many patches with geometrical constraints for the representation of complex geometries are some of the main difficulties of using spline surfaces. In this presentation, we will discuss several of these aspects and show two promising and controllable techniques for intuitive use of parametric surface-based representations in 3D geological and reservoir modelling.
An Integrative Information Aqueduct to Close the Gaps between Global Satellite Observation of Water Cycle and Local Sustainable Management of Water Resources (iAqueduct)
Authors: zeng yijian ,   iAqueduct Team
Published: March 2020

In the past decades, space-based Earth Observations (EO) have been rapidly advancing in monitoring the global water cycle, in particular for the variables related to precipitation, evapotranspiration and soil moisture, often at (tens of) kilometre scales. Whilst these data are highly effective to characterise water cycle variation at regional to global scale, they are less suitable for sustainable management of water resource, which needs more detailed information at local and field scale due to inhomogeneous characteristics of the soil and vegetation. To effectively exploit existing knowledge at different scales we thus need to answer the following questions: How to downscale the global water cycle products to local scale using multiple sources/scales of EO data? How to explore and apply the downscaled information at the management level for understanding soil-water-vegetation-energy processes? And how to use such fine-scale information to improve the management of soil and water resources? An integrative information aqueduct (iAqueduct) is proposed to close the gaps between global satellite observation of water cycle and local needs of information for sustainable management of water resources. iAqueduct aims to accomplish its goals by combining Copernicus satellite data (with intermediate resolutions) with high resolution Unmanned Aerial System (UAS) and in-situ observations to develop scaling functions for soil properties and soil moisture and evapotranspiration at high spatial resolution scales.
How can REE-bearing minerals help us refine our understanding of crustal evolution and Archean tectonics?
Authors: Bruand Emilie , Storey Craig , Fowler Mike
Published: March 2020

Delineating the evolution of the Earth’s dynamics and interactions between its different silicate reservoirs (ocean crust, continental crust, mantle) is key to understanding planetary differentiation and the conditions of surface habitability. Today, plate tectonic processes play a major role in creating and destroying the Earth’s crust, and modifying its silicate mantle. For this reason the Earth is unique in the solar system. Reconstructing its long-term evolution is, however, extremely difficult since the Hadean record is essentially missing and most Archean rocks have experienced reworking and overprinting of their original signatures. 

In this presentation, we will explore the constraints available with isotopic and chemical information from REE-bearing minerals in magmas that appear at different times during Earth history. We present, new geochemical data on these phases from a compilation of granitoids that cover a large span of the geological record from the Archean to the Phanerozoic. We demonstrate that trace element analysis and detailed petrographic work can give direct information about the petrogenesis of the host magmas even when these granitoids have been affected by metamorphism. Other studies focusing on rutile have shown that it records important information on metamorphic conditions in the Archean. On the other hand, and also helpfully, all three minerals are resistant to secondary processes and erosion, and thus may also offer significant archives of pertinent information in the detrital rock record. Development of such petro-geochemical tools could deliver complementary information to that provided by zircon and have significant potential for provenance studies and for tracing the secular evolution of the Earth.
The role of extreme noise in tipping between stable states
Authors: Ditlevsen Peter
Published: March 2020

Paleoclimatic records show that under glacial boundary conditions the climate has jumped irregularly between two different climate states. These are the stadial and interstadial climates characterized by extremely abrupt climate change, the Dansgaard-Oeschger events. The irregularity and the fact that no known external triggering is present indicate that these are induced by internal noise, so-called n-tipping. The high resolution record of dust from Greenland icecores, which is a proxy of the state of the atmosphere, can be well fitted by a non-linear 1D stochastic process. But in order to do so the noise process needs to be an alpha-stable process, which is characterized by heavy tails violating the central limit theorem.  I will discus how extreme events can influence the transition from one climate state to the other.