bluuebunny/crossref_metadata_2025 huggingface dataset:
Inter-Calibrating Satellite Remote Sensors Using High Accuracy NASA CLARREO Pathfinder Instrument
Authors: Liu Xu , Wu Wan , Yang Qiguang , Shea Yolanda , Lukashin Costy , Fleming Gary
Published: March 2020

NASA is planning to launch a highly accurate hyperspectral sensor to measure Earth-reflected solar radiances from the International Space Station in 2023.  The Climate Absolute Radiance and Refractivity Observatory (CLARREO) Pathfinder (CPF) instrument will have an absolute calibration accuracy of 0.3% (1-sigma), which is about a factor of 5 to 10 more accurate than current satellite reflected solar instruments.  We will describe the CPF approach developed to inter-calibrate the Clouds and Earth’s Radiant Energy System (CERES) and Visible Infrared Imaging Radiometer Suite (VIIRS) instruments.  A Principal Component-based Radiative Transfer Model (PCRTM) is used to perform high fidelity CPF radiance spectra simulation and to extend the spectral range of the CPF to match that of the shortwave CERES reflected solar radiation.  The PCRTM model can also be used to correct small errors due to imperfect angular matching between the CPF/CERES and CPF/VIIRS observation angles.  Examples of inter-calibration uncertainty that is anticipated will be demonstrated using simulated CPF data.
Imaging biogeochemical gradients in the rhizosphere
Authors: Rudolph-Mohr Nicole , Bereswill Sarah , Tötzke Christian , Kardjilov Nikolay , Oswald Sascha E.
Published: March 2020

Dynamic processes occurring at the soil-root interface crucially influence soil physical, chemical, and biological properties at local scale around the roots that are technically challenging to capture in situ. Combining 2D optodes and 3D neutron laminography, we developed a new imaging approach capable of simultaneously quantifying H2O-, O2-, and pH-distribution around living plant roots while additionally capturing the root system architecture in 3D. The interrelated patterns of root growth and distribution in soil, root respiration, root exudation, and root water uptake can be studied non-destructively at high temporal and spatial resolution.

Neutron computed laminography (NCL), a tomographic approach specially adapted to samples with large lateral extension (here 15 x 15 x 1.5 cm) was applied to visualize the root architecture and soil water content three-dimensionally. Optodes, sensitive to pH and O2 changes, were attached at the inner-sides of thin boron-less glass-containers where one maize plant was grown in each container. Knowledge about the distance of the roots from the container walls and thus from the optodes, support the interpretation of the optical images.

Neutron laminography made it possible to visualize and quantify the 3D root system architecture in association with the observed H2O, pH and oxygen patterns. The older part of the root system with higher root length density was associated with fast decrease of water content and rapid change in oxygen concentration. Lateral roots acidified their rhizosphere by a quarter of a pH unit and crown root even induced acidification of up to one pH unit compared to bulk soil. The benefit of neutron laminography is that we can extract the root structure in 3D, identify root age and root types and relate this to spatiotemporal changes in water content distribution, oxygen concentration and pH values.
Stable isotope analysis for control of declared geographic origin of Austrian and Slovak apricots: The IDARPO-Interreg-Project (AT-SK)
Authors: Horacek Micha
Published: March 2020

Food products of certain geographic origin are more valued by consumers than the same commodities from other regions. Therefore, there is the risk and fear that incorrect labelling and declaration of geographic origin can occur to increase profit. Thus, a control of declared geographic origin is required to ensure correct labelling and to identify fraud.

For this purpose, apricot samples of the recent vintage (2019) are investigated to differentiate samples from different apricot-producing regions in Austria, Slovakia and other countries. The isotope composition of the elements hydrogen (H), carbon (C), nitrogen (N) and oxygen (O) of fruit pulp (H, C, N, O), fruit stone (H, C, O) and fruit juice (O) is analysed to find appropriate parameters for the differentiation of geographic origin. The investigation of different sample tissues (pulp, stone, juice) supports a better differentiation of geographic origin due to different seasonal intervals influencing the respective commodities.

Within the frame of the project 3 vintages will be investigated and analysed for stable isotopes as well as other analytical techniques (molecular markers). The combination of all sample data (including previously accumulated data, e.g. Horacek 2017, Horacek 2019) will lead to an improved differentiation and identification of geographic origin.

This work is a contribution to the Interreg project IDARPO partially funded by the EU-Interreg program.

References:

Horacek, M., 2017, Isotope investigation of apricots from the Wachau-area/Lower Austria („Wachauer Marille“) to control the declared geographic origin: A pilot study – first results. Mitteilungen Klosterneuburg. 67, p. 219-228.

Horacek, M., 2019, Stable isotope analysis for control of declared geographic origin of Austrian apricots. EGU 2019, Vienna.
Design of rainwater detention basins
Authors: Rosbjerg Dan
Published: March 2020

Traditionally in Denmark, rainwater detention basins are designed based on an input box rain with a given return period and a constant outflow from the basin. The water authorities specify the outflow rate in order to avoid erosion in the recipient. Intensity-Duration-Frequency (IDF) curves are used as a prerequisite for the method. Given the design return period, and varying the duration of the box rain, the basin volume that prevents spill from the basin can be determined. By analysing for a series of outflow rates, a basin volume curve for the selected return period can be developed. The current practice is revisited, and a new analytical solution for the duration of the design rain is found.

A constant outflow rate for the basin is, however, not always a realistic assumption, and thus there is a risk for underestimation. An alternative design method has been analysed, assuming that the outflow from the basin takes place corresponding to at linear reservoir with maximum outflow rate equal to the one specified by the water authorities. The method is described in detail, and the results compared with those of the current guidelines.
Reactive Flow Model for Porosity Reduction by Quartz Dissolution/Precipitation
Authors: Gisler Batoul , A. Miller Stephen
Published: March 2020

Quartz dissolution and precipitation is an important pore reducing process in geothermal reservoirs. We present a single-phase reactive flow model coupled with hydrodynamic flow and heat transfer components and implement it into COMSOL Multiphysics. The model includes diffusion and advection, and analytical equations are used to describe quartz kinetics and equilibrium concentrations with respect to the silicate phases. The numerical model can a priori be used to analyze the evolution of the porosity/permeability, and hence the productivity of the reservoir induced by heat extraction in geothermal reservoirs. A geothermal reservoir is modeled with realistic time steps, where its geometry is represented as a porous medium block in which chemical reactions occur between the pore fluid and the rock matrix. Future developments include adding a fracture and fracture networks to the system and analyzing the changes in effective stresses in the presence of reactive flow. Economic reservoir development requires a combined analysis of the thermo-hydro-mechanical and chemical processes, and precipitation processes may be important in post-seismic fluid flow processes.
Preliminary results from interdisciplinary fault characterization in the Bedretto Underground Laboratory
Authors: Shakas Alexis , Krietsch Hannes , Hertrich Marian , Gholizadeh Nima , Plenkers Katrin , Maurer Hansruedi , Meier Matthias , Loew Simon , Nejati Morteza , Hochreutener Rebecca , Ma Xiaodong , Wiemer Stefan , Driesner Thomas , Giardini Domenico , Serbeto Francisco , Castilla Raymi , Meier Peter
Published: March 2020

Engineered Geothermal Systems (EGS) are gaining increasing popularity as a source of renewable energy without significant CO2 emissions. Fractured crystalline rock masses offer a promising environment for exploitation of geothermal energy. In such a setting, fractures and faults are the main conduits for fluid flow and heat transport. In-situ fracture permeabilities are usually too low at depths where rock mass temperatures are sufficiently high for geothermal energy production. Therefore, a suitable heat exchanger needs to be engineered by hydraulic stimulations. A proper in-situ characterization of the fracture geometry and hydro-mechanical properties is of primary importance for the design of the stimulation operations. This is often the most challenging task, since the majority of the fractures in the reservoir are usually inaccessible for direct characterization.

 

The Bedretto Underground Laboratory for Geosciences (BULG) provides a novel and unique environment to study EGS-related processes, such as seismo-hydro-mechanical fault zone response during hydraulic stimulation and subsequent fluid circulation experiments. The laboratory is hosted in an access tunnel from the Bedretto Valley in the Southern Swiss Alps to a railway tunnel from the Matterhorn-Gotthard-Bahn. The overburden of more than 1000 m above the BULG provides conditions that are approaching those of realistic EGS systems. For the rock mass characterization, three boreholes were drilled perpendicular to tunnel axis with lengths ranging from 190 m to 300 m.

 

We present first data sets from a variety of methodologies, ranging from hydrological tests to geophysical borehole- and remote-imaging. The complementary nature of these data sets allows us to construct a preliminary three dimensional geological model. Notably, the individual measurements yielded information over a multitude of scales, ranging from millimeter-scale core-log information to decameter scale low-frequency Ground Penetrating Radar measurements. Such a wide range of scales is critical for the characterization of EGS reservoirs. The most prominent feature found is a large-scale fracture zone that extends across the entire investigation volume. This fracture zone will be the target for upcoming stimulation experiments.
Towards synthetic data generation for machine learning models in weather and climate
Authors: Meyer David
Published: March 2020

The use of real data for training machine learning (ML) models are often a cause of major limitations. For example, real data may be (a) representative of a subset of situations and domains, (b) expensive to produce, (c) limited to specific individuals due to licensing restrictions. Although the use of synthetic data are becoming increasingly popular in computer vision, ML models used in weather and climate models still rely on the use of large real data datasets. Here we present some recent work towards the generation of synthetic data for weather and climate applications and outline some of the major challenges and limitations encountered.
Relative abundance diagnostics with SPICE, the EUV spectrometer on-board Solar Orbiter
Authors: Zambrana Prado Natalia , Buchlin Eric , Peter Hardi
Published: March 2020

With the launches of Parker Solar Probe and Solar Orbiter, we are closer than ever to linking solar activity on the surface and in the corona to the inner heliosphere. In this quest, relative abundance measurements will be key as different structures on the Sun have different abundances as a consequence of the FIP (First Ionization Potential) effect.

Comparing in-situ and remote sensing composition data, coupled with modeling, will allow us to trace back the source of heliospheric plasma. Solar Orbiter has a unique combination of in-situ and remote sensing instruments that will hopefully allow us to make such comparisons.

High telemetry will not always be available with SPICE (SPectral Imaging of the Coronal Environment), the EUV spectrometer on board Solar Orbiter. We have therefore developed a method for measuring relative abundances that is both telemetry efficient and reliable. Unlike methods based on Differential Emission Measure (DEM) inversion, the Linear Combination Ratio (LCR) method does not require a large number of spectral lines. This new method is based on optimized linear combinations of only a few UV spectral lines. We present some abundance diagnostics applied to synthesized radiances of spectral lines observable by SPICE.
Scale discrepancy paradox between observation and modelling in fractured reservoir models in oil and gas industry.
Authors: Richard Pascal , Bazalgette Loïc
Published: March 2020

Naturally fractured reservoirs represent one of the most challenging resource in the oil and gas industry. The understanding based on centimeter scale observations is upscaled and modeled at 100-meter scale.

In this paper, we will illustrate with case study examples of conceptual fracture model elaborated using static and dynamic data, the disconnect between the scale of observation and the scale of modelling. We will also discuss the potential disconnect between the detail of fundamental, but necessary, research work in universities against the coarse resolution of the models built in the oil industry, and how we can benefit of the differences in scales and approaches.

 

The appraisal and development of fractured reservoirs offer challenges due to the variations in reservoir quality and natural fracture distribution. Typically, the presence of open, connected fractures is one of the key elements to achieve a successful development. Fracture modelling studies are carried out routinely to support both appraisal and development strategies of these fractured reservoirs.

Overall fracture modelling workflow consists first of a fracture characterization phase concentrating on the understanding of the deformation history and the evaluation of the nature, type and distribution of the fractures; secondly of a fracture modelling part where fracture properties for the dynamic simulation are generated and calibrated against dynamic data. The pillar of the studies is the creation of 3D conceptual fracture diagrams/concepts which summarize both the understanding and the uncertainty of the fracture network of interest. These conceptual diagrams rely on detailed observations at the scale of the wellbore using core and borehole image data which are on contrasting scale compare to the 10’s of meters to 100’s of meter scale of the grid cells of the dynamic models used for the production history match and forecast. These contrasting scales will be the thread of the presentation.
Theoretical limits and new approaches to reconstruct temperature from the isotopic composition of ice cores in low-accumulation regions
Authors: Laepple Thomas , Münch Thomas , Casado Mathieu , Hörhold Maria , Freitag Johannes , Werner Martin , Dallmayr Remi
Published: March 2020

For several decades, ice-core water-isotope research was focused on retrieving and interpreting single cores, measured on increasingly finer resolution and higher analytic precision. However, not only the sampling resolution or analytical precision limits the ability to recover the climate signal, but also the way the climatic signal is imprinted in the isotopic composition profile obtained from ice cores. Therefore, despite three decades of Antarctic ice-coring and dozens of firn cores, especially the temperature evolution in the low accumulation region of East Antarctica during the last millennium is still barely known.  In the recent years, strong progress has been made in the understanding of the isotopic signal formation based on process studies, snow pits, snow trenches and replicate cores. Using this knowledge, we will review the limits of temperature reconstructions based on theoretical considerations, empirical signal-to-noise ratio estimates and forward models of the signal formation. We will further discuss new avenues for sharpening the ability to recover high-resolution temperature signals from firn and ice cores by optimally combining multiple cores and by combining isotope with impurity records.
Monitoring recent activity of the Koytash Landslide (Kyrgyzstan) using radar and optical remote sensing techniques
Authors: Piroton Valentine , Schlögel Romy , Havenith Hans-Balder
Published: March 2020

Landslides are recurrent in most mountainous areas of the world where they frequently have catastrophic consequences. Around the Fergana Basin and in the Maily-Say Valley (Kyrgyzstan), landslides are often reactivated due to intense rainfalls, especially during spring, and as a consequence of the high seismicity characterizing the region. In spring 2017, Kyrgyzstan suffered a massive activation event which caused 160 emergency situations, including the reactivation of Koytash, one of the largest deep-seated mass movements of the Maily-Say area. In this region, risks related to landslides are accentuated by the presence of uranium tailings, remnants of the former nuclear mining activity. In this study, we used multiple satellite remote sensing techniques to highlight deformation zones and identify displacements prior to the collapse of Koytash. The comparison of multi-temporal digital elevation models (DEMs; satellite and UAV-based) enabled us to highlight areas of depletion and accumulation, in the scarp and foothill zones respectively. A differential synthetic aperture radar interferometry (D-InSAR) analysis and the computation of deformation time series allowed us to identify slope displacements and estimate the evolution of the displacement rates over time. This analysis identified slow displacements during the months preceding the reactivation, indicating the long-term sliding activity of Koytash, well before the reactivation in April 2017. This was confirmed by the computation of deformation time series, showing a positive velocity anomaly on the upper part of Koytash. Furthermore, the use of optical imagery, through the difference of NDVIs (Normalized Difference Vegetation Index), revealed landcover changes associated to the sliding process. In addition to remote sensing techniques, we performed a meteorological analysis to identify the conditions that triggered the massive failure of Koytash. In-situ data from a local station highlighted the important contribution of precipitations as a trigger of the landslide movement. Indeed, despite a relative decrease in annual rainfall in 2017 compared to the previous years, the month of April 2017 was characterised by heavy rains, including a major peak of rainfall the day of Koytash’s failure. The multidirectional approach used in this study, demonstrated the efficiency of using multiple remote sensing techniques, combined to a meteorological analysis, to identify triggering factors and monitor the activity of landslides.
How Global Warming Changes the Difficulty of Synoptic Weather Forecasting
Authors: Scher Sebastian , Messori Gabriele
Published: March 2020

Little is known on whether and how global warming may affect the atmosphere's predictability and thus our ability to produce accurate weather forecasts. Here, we combine a climate and an ensemble weather prediction model to show that, in a business-as-usual 21st century setting, global warming could significantly change the predictability of the atmosphere, defined here via the expected error of weather predictions. Predictability of synoptic weather situations could significantly increase, especially in the Northern Hemisphere. This can be explained by a decrease in the meridional temperature gradient, which seems to control the inter-annual variability of atmospheric predictability. Contrarily, summertime predictability of weekly rainfall sums might significantly decrease in most regions.
Paleomagnetism of the Kola Peninsula's dykes, NE Fennoscandia: the review
Authors: Veselovskiy Roman , Stepanova Alexandra , Samsonov Alexander , Lebedev Ivan
Published: March 2020

In this work we present the overview of comprehensive research on paleomagnetism and rock magnetism of more than 120 Paleoproterozoic and Neoarchean dykes from the Kola Peninsula, NE Fennoscandia. We discuss our results in a context of Precambrian paleotectonic reconstructions of Fennoscandia and Murmansk craton in particular for the time intervals corresponding to the dyke magmatism. We also show our progress in dating of the remanent magnetization components using some approaches of isotope geochronology, such as U-Pb dating of baddeleyite and Ar/Ar dating of mica, feldspar and amphibole. In total, we have been able to calculate virtual geomagnetic poles for the selected dykes and to make some conclusions about paleotectonics of the Murmansk craton at the corresponding time. New paleointensity data for some 2.50 and 2.68 Ga dykes will be also presented and commented. The study is supported by the grant of RSF #16-17-10260.
Smart4RES: Towards next generation forecasting tools of renewable energy production
Authors: Kariniotakis George , Camal Simon , Bessa Ricardo , Pinson Pierre , Giebel Gregor , Libois Quentin , Legrand Raphaël , Lange Matthias , Wilbert Stefan , Nouri Bijan , Neto Alexandre , Verzijlbergh Remco , Sauba Ganesh , Sideratos George , Korka Efrosyni , Petit Stephanie
Published: March 2020

The aim of this paper is to present the objectives, research directions and first highlight results of the Smart4RES project, which was launched in November 2019, under the Horizon 2020 Framework Programme. Smart4RES is a research project that aims to bring substantial performance improvements to the whole model and value chain in renewable energy (RES) forecasting, with particular emphasis placed on optimizing synergies with storage and to support power system operation and participation in electricity markets. For that, it concentrates on a number of disruptive proposals to support ambitious objectives for the future of renewable energy forecasting. This is thought of in a context with steady increase in the quantity of data being collected and computational capabilities. And, this comes in combination with recent advances in data science and approaches to meteorological forecasting. Smart4RES concentrates on novel developments towards very high-resolution and dedicated weather forecasting solutions. It makes optimal use of varied and distributed sources of data e.g. remote sensing (sky imagers, satellites, etc), power and meteorological measurements, as well as high-resolution weather forecasts, to yield high-quality and seamless approaches to renewable energy forecasting. The project accommodates the fact that all these sources of data are distributed geographically and in terms of ownership, with current restrictions preventing sharing. Novel alternative approaches are to be developed and evaluated to reach optimal forecast accuracy in that context, including distributed and privacy-preserving learning and forecasting methods, as well as the advent of platform-enabled data-markets, with associated pricing strategies. Smart4RES places a strong emphasis on maximizing the value from the use of forecasts in applications through advanced decision making and optimization approaches. This also goes through approaches to streamline the definition of new forecasting products balancing the complexity of forecast information and the need of forecast users. Focus is on developing models for applications involving storage, the provision of ancillary services, as well as market participation.
Infiltration experiments with ultra-high spatial and temporal resolution of saturation measurements
Authors: Siemens Greg , Oldroyd Chris , Beddoe Ryley
Published: March 2020

Near surface hydrological processes whereby moisture exchange occurs between the vadose zone and above-ground weather systems occur on daily, seasonal, and long-term cycles. Well-controlled laboratory studies of near surface moisture migration are often limited due to number of measurement points of moisture content and pore pressure. This presentation will describe experimental and digital image analysis techniques incorporating a refractive index matched soil-pore fluid combination that increase spatial resolution of saturation measurements by over 6 orders of magnitude. The refractive index matched material changes color from black (Saturation=1) to white (Saturation=0) allowing for saturation measurements at the digital pixel scale. This visualization technique allows for direct observation of flow effects which affect boundary measurements and local flow mechanisms. The capabilities of unsaturated transparent soil are incorporated in a 2D infiltration apparatus to examine the influence of confined air on infiltration. 2D experiments agree with previous column infiltration results showing air confinement decreases infiltration rate by more than one half. The 2D apparatus allows a clear unstable wetting front to develop, visualization of dynamic moisture migration within the transmission zone. In addition, the high spatial resolution saturation measurements show detectable influence of thin heterogeneities on wetting front migration and the influence of flow direction on saturation distribution. The high-resolution saturation measurements will allow for calibration of computational models multi-phase flow and open up new insight into near surface processes to improve water balance calculations and soil-structure-climate interactions.
Cloud condensation nuclei (CCN) measurements with the HALO aircraft during EMeRGe in European and Asian airspace
Authors: Pöhlker Mira L. , Krüger Ovid O. , Holanda Bruna A. , Pöhlker Christopher , Klimach Thomas , Su Hang , Cheng Yafang , Nenakhov Vladyslav , Andrés Hermándes Maria D. , Burrows John P. , Pöschl Ulrich
Published: March 2020

During the EMeRGe campaign we employed a cloud condensation nuclei counter (CCNC) on board the research aircraft HALO. The instrument was located in the CCN-Rack probing together with a single particle soot photometer (SP2) and a multi-impactor for sampling different air masses on silica nitrate substrates. The aerosol particles were sampled through the HALO Aerosol Submicrometer Inlet (HASI). The measurements have been performed with a two column continuous-flow longitudinal thermal-gradient instrument (CCN-200) manufactured by DMT. The CCN-200 measures the CCN number concentration as a function of water vapor supersaturation (S). These measurements are performed by changing S within one column from 0.10 % up to 1.00 % using 12 different supersaturations and keeping S constant within the second column (S = 0.38 %) to ensure baseline data with 1 Hz time resolution. The different supersaturations are created by changing the flow while setting a fixed temperature difference.

Purpose of EMeRGe is to quantify and qualify outflows of megacities, as well as their transport and transformation in the atmosphere. Therefore, measurement flights were performed in the European airspace in 2017, probing aerosol properties over cities like London, Barcelona and Rome. In March 2018, the same set of instruments was probing the outflows of Asian megacities like Taipei, Manila and aged pollution from China Mainland. Furthermore, Japanese and South Korean outflows could be probed. The measurements took place in altitudes between 0.3 km and 13 km ASL. The scientific objective is to investigate the effect of different pollution states on aerosol and CCN properties.
Oil spill forecasting systems uncertainty assessment in the Aegean Sea
Authors: Kampouris Konstantinos , Vervatis Vassilios , Karagiorgos John , Sofianos Sarantis
Published: March 2020

The Aegean Sea is one of the world’s busiest waterways, combined with complex and intense weather and sea current patterns with strong seasonality, complicated coastline and bathymetry. Therefore, the uncertainty assessment of the oil spill forecasting systems in this region is of great interest. The purpose of this study is to evaluate the impact of the uncertainty of the atmospheric forcing on the performance of the oil spill modelling and the dispersion of the pollutants in the marine environment. Ensemble simulations were carried out using the ECMWF Ensemble Prediction System and the oil spill model MEDSLIK II. The Aegean Sea was chosen as the study area performing ensembles of 50 members with seven days forecast lead time, during different seasons. Three types of oil were chosen representing lighter, medium and heavier oil spills, covering also a wide range of oil densities. The oil spill duration and the spill rate were chosen taking into account significant accidents of the past like for instance the Prestige case. Preliminary results suggest that the model errors in the oil spill trajectories are sensitive to the atmospheric forcing uncertainties.

Keywords: Aegean Sea, MEDSLIK II, Oil spill, ensemble simulation, uncertainty
How tail reconnection affects the asymmetric state of the magnetosphere in the LFM model
Authors: Ohma Anders , Østgaard Nikolai , Reistad Jone Peter , Laundal Karl M. , Tenfjord Paul
Published: March 2020

The IMF By component is a source of numerous asymmetric features in our magnetospheric system, e.g. north-south asymmetries in the aurora, the magnetospheric and ionospheric current systems and the plasma convection. Several recent studies have shown that asymmetries in the lobe pressure play a major role in inducing these asymmetries. It has also been reported that enhanced tail reconnection affects the dynamics of the system by reducing the north-south asymmetries imposed by the IMF. A possible interpretation of these observations is that enhanced reconnection in the near-Earth tail reduces the pressure in the lobes and thus suppresses the cause of the initial asymmetry. In this study, we present the results from global MHD simulations using the LFM model to further investigate how enhanced tail reconnection affects the asymmetric state of the system. A relaxation of the asymmetry in the closed magnetosphere is seen in the model when the reconnection rate in the tail increases, consistent with observations, and we use the simulation output to gain further insight into the physical mechanism(s) responsible for the return to a more symmetric state.
Formation Water Characterization of the Shale Reservoir Rocks Using Integrated Workflow
Authors: Kazak Ekaterina , Kazak Andrey , Bilek Felix
Published: March 2020

The paper presents the results of a novel integrated solution of formation water content and salinity determination of the low permeability reservoir rock of Bazhenov formation (West Siberia, Russia) for petrophysical characterization. The workflow is based on three techniques: evaporation method (EM) with isotopic composition analysis, analysis of water extracts, and cation exchange capacity (CEC) study. The EM offers a fast, efficient, and accurate measurement of the residual water content with breakdown to free and loosely clay-bound types. The isotopic composition reveals the origin and genesis of pore water. The chemical analysis of water extracts delivers a lower bound salinity in terms of NaCl. CEC describes rock-fluid interactions. The two methods of cation exchange capacity (CEC) measurement were applied – alcoholic NH4Cl ((NH4Cl)Alc) and hexammnninecobalt(III) chloride (CoHex) method. Both showed similar results. CEC varies from 2.87 to 5.82 meq/kg by ((NH4Cl)Alc method and from 2.87 to 6.38 cmol/kg by CoHex method and depends on the clay content. Ca, Na, Mg, K form exchange complex of all studied core samples. According to interrelation (rNa+rK)>rCa the exchange complex type is marine and was inherited from the composition of the paleobasin seawater.

The target rock samples contained the residual formation water 0.11–4.27 wt.%, including free 0.04–3.92 wt.% and loosely clay-bound water 0.09–0.96 wt.%. The loosely bound water content correlates well to the clay mineral fraction. The amount of chemically bound water fell in a range of 0–6.40 wt.% and exceeds that of free and loosely bound water.

We found that water extract composition depends on the core mineral content, except chlorine and bromine, which originates from the pore water. Using the thermodynamic modelling in PHREEQC program, next ratio of cations in pore water was found - Na (up to 91%), Mg (up to 5.6%), Ca (up to 2.6 %) and K (up to 0.8%). According to the calculation using the water extracts results, the pore water salinity as NaCl changes from 1.23 to 21.96 g/L. The corresponding isotopic composition indicated the deep formation genesis and generally correlated to that of the deep stratal waters of the West Siberia. Isotopic composition proved the formation origin of extracted pore water samples.

The study made a qualitative step up towards the quantitative characterization of formation water in shale reservoir rocks with the initial water content of less than 1 wt.%.

This work was supported by the Russian Science Foundation (grant No. 17-77-20120).
Geomorphic imprint of dynamic topography and intraplate tectonism in central Australia
Authors: Jansen John , Sandiford Mike , Fujioka Toshiyuki , Cohen Timothy , Struck Martin , Anderson Suzanne , Anderson Robert , Egholm David
Published: March 2020

The mantle convection accompanying plate motion causes vertical movements of up to a few hundred metres at Earth’s surface over wavelengths of 102–103 km. This dynamic topography appears to come and go at ~ 1–10 Myr timescales in areas that are often well away from plate margins, although its spatial and temporal characteristics are subject to ongoing debate. Since such motions are small and transient, discriminating convective signals from other drivers of relief generation and/or sediment dispersal remains tricky. An outstanding challenge is to detect these elusive, transient undulations from a tell-tale geomorphic imprint preserved in either drainage patterns or the stratigraphic record.

In the intra-plate setting of central Australia, a 30 km long sinuous gorge is developed where the major regional drainage, Finke River, dissects a band of low hills. Remarkably, this gorge is intertwined with an abandoned and less deeply incised gorge that forms hanging junctions and shares similar width and sinuosity. This unusual overprinting of the two gorges remains unexplained.

With an aim to investigate the history of the intertwined gorges, we measured cosmogenic 10Be and 26Al in fluvial gravels stored in the palaeovalley cutoffs. The gravels are remnants of major alluviation episodes that we surmise result from ongoing vertical motions associated with dynamic topography. We use a Markov chain Monte Carlo-based inversion model to test two hypotheses to explain the nuclide inventory contained within the stored fluvial gravels. In the first case, rapid alluviation and erosion since 1 Ma preserves the nuclide memory of the source area; in the second, the nuclide memory is erased during long-term fluvial storage (> 5 Myr) and is restored during exhumation of the palaeovalley gravel-pile. The two hypotheses are therefore limiting-case scenarios that constrain overall fast versus slow landscape evolution, respectively. Our model results suggest that long-term burial decouples the source-area signal from nuclide abundances measured in the palaeovalley gravels. This casts events into a Miocene timescale.
Climatology reflected by infrasound travel-times sampling the stratosphere in its transition between summer and winter
Authors: Vera Rodriguez Ismael , Näsholm Sven Peter , Turquet Antoine L. , Evers Läslo G.
Published: March 2020

Like seismic waves traveling through the solid earth, infrasound waves traveling through the atmosphere are also sensitive to the medium properties – in particular to temperature and wind. The exploitation of this information is particularly interesting in regions and altitude ranges where other
measurements are sparse. In this work, we look at the climatology from first-arrival travel-times using a dataset of infrasound observations from northern Scandinavia, this is, in the context of stratospheric temperatures.

The same dataset has recently been exploited to estimate tropospheric and stratospheric cross-winds. This dataset spans 30 years and corresponds to explosions that are due to the destruction of ammunition at a military site in Finland conducted over the months of August and September; hence, it
covers the period of transition from summer to winter stratosphere. The transition between summer and winter stratosphere is clear in the data. However, a significant travel-time variation between years produces inconclusive results when inferring stratospheric temperature trends over the 30 years analyzed. Still, when comparing the travel-times against regional stratospheric temperatures represented in atmospheric re-analysis models, there is a correspondence between models and infrasound data.
Accounting for model error in atmospheric forecasts
Authors: Crawford William , Frolov Sergey , McLay Justin , Reynolds Carolyn , Bishop Craig , Ruston Benjamin , Barton Neil
Published: March 2020

The presented work will illustrate the impact of analysis correction based additive inflation (ACAI) on atmospheric forecasts. ACAI uses analysis corrections from the NAVGEM data assimilation system as a representation of model error and is shown to simultaneously improve ensemble spread-skill, reduce model bias and improve the RMS error in the ensemble mean. Results are presented from a myriad of experiments exercising ACAI in stand-alone NAVGEM forecasts using two different ensemble systems; (1) the current operational EPS at FNMOC based on the ensemble transform method and (2) the Navy-ESPC EPS based on perturbed observations. The method of relaxation-to-prior-perturbations (RTPP) has also been implemented in the Navy-ESPC EPS and is shown to further improve the ensemble spread-skill relationship by allowing variance generated during the forecast to impact the initial-time ensemble variance in the subsequent cycle. Results from a simplified implementation of ACAI in the NAVGEM deterministic system will also be shown and indicate positive impact to model biases and RMSE.
Sr isotopes indicate millennial-scale formation of metal-rich layers by reactive melt percolation in an open-system layered intrusion
Authors: Daly J. Stephen , Hepworth Luke , O'Driscoll Brian , Johnson Chris , Gertisser Ralf , Emeleus C. Henry
Published: March 2020

In order to test whether the crystal mushes that form layered mafic intrusions can behave as open systems, we investigated mineral-scale textural, chemical and Sr isotopic heterogeneity in the c. 60 Ma Rum intrusion, Scotland. Within Unit 10 of the Rum intrusion, intercumulus plagioclase and clinopyroxene crystals in peridotite 1-2 cm above and below millimetric Cr-spinel seams exhibit complex optical and chemical zoning (Hepworth et al. 2017). These Cr-spinel seams are closely associated with sulphide and platinum-group element (PGE) mineralization. High precision Sr isotopic analyses (undertaken by thermal ionisation mass spectrometry) of individual intracrystal zones (sampled by micromilling) in intercumulus plagioclase and clinopyroxene from within the PGE-enriched Cr-spinel seams have revealed significant intra-crystalline heterogeneity. 87Sr/86Sr heterogeneity is present between plagioclase crystals, between clinopyroxene and plagioclase, and within plagioclase crystals, throughout the studied section. The preservation of Sr isotope heterogeneities at 10-100 µm length-scales implies cooling of the melts that formed the precious metal-rich layers at rates >1 °C per year, and cooling to diffusive closure within 10s-100s of years. The combined textural observations and intra-crystal plagioclase 87Sr/86Sr data also highlight the importance of repeated cycles of dissolution and recrystallization within the crystal mush, and together with recent documentation of ‘out-of-sequence’ layers in other layered intrusions (Mungall et al. 2016; Wall et al. 2018), raise the prospect that basaltic magmatic systems may undergo repeated self-intrusion during solidification.

Hepworth, L.N., O’Driscoll, B., Gertisser, R., Daly, J.S. and Emeleus, H.C. 2017. Journal of Petrology 58, 137-166; Mungall, J. E., Kamo, S. L. & McQuade, S. 2016. Nature Communications 7, 13385; Wall, C. J., Scoates, J. S., Weis, D., Friedman, R. M., Amini, M. & Meurer, W. P. 2018. Journal of Petrology 59, 153–190.
Rikitake Law, relating precursor time and earthquake magnitude, confirmed by Swarm satellite data
Authors: Campuzano Saioa A. , Cianchini Gianfranco , De Santis Angelo , Marchetti Dedalo , Perrone Loredana , Piscini Alessandro , Sabbagh Dario
Published: March 2020

Rikitake [1987] studied different types of ground earthquake precursors and presented an empirical law (for what he called “precursors of the 1st kind”) expressing a linear relationship between the logarithm of the anomaly precursor time and the earthquake magnitude. To look for possible in-situ ionospheric precursors of large (M5.5+) earthquakes, here we analyse a long-term time series data from the three-satellite Swarm constellation, in particular electron density and magnetic field data. We define the anomalies statistically in the whole space-time interval of interest and use a superposed epoch approach to study the possible relation with the earthquakes. We find some clear concentrations of electron density and magnetic anomalies from several months to a few days before the earthquake occurrences. Such anomaly clustering is, in general, statistically significant with respect to homogeneous random simulations, supporting a coupling of the lithosphere with the above atmosphere and ionosphere during the preparation phase of earthquakes. Finally, by investigating different earthquake magnitude ranges, we confirm the Rikitake empirical law between ionospheric anomaly precursor time and earthquake magnitude. Our work represents the first time that this empirical law has been confirmed for satellite data. We also explain this empirical law with a diffusion model of lithospheric stress.
Switches of Holocene temperature-precipitation correlations in northern Hemisphere extra-tropics comparing proxy and model data
Authors: Herzschuh Ulrike , Boehmer Thomas , Herbert Raphael , Laepple Thomas , Telford Richard , Cao Xianyong , Dallmeyer Anne , Kruse Stefan
Published: March 2020

Switches of temperature-precipitation correlation in northern Hemisphere extra-tropics

Future precipitation response to warming remains uncertain because climate models poorly reproduce observed changes of temperature-precipitation correlations. However, restricting model validations to the observational period may yield to misleading conclusions due to the complexity of the involved processes. Our analyses of Holocene proxy-based temperature-precipitation correlations from 1500 northern Hemisphere extratropic pollen records portrayed significant latitudinal dependance, temporal changes from the early to late Holocene as well as differences between short and long time-scales. These observed variations were found to be mostly consistent with patterns simulated by Holocene transient climate simulations. Our results suggest that the strength of positive temperature-precipitation correlations in high-latitudes is sensitive to the background temperature while monsoonal subtropics reflect spatial shifts of circulation systems; and correlation sign switches in mid-latitudes relate to changes of westerlies strength. We conclude that regional and continental climate change on land is more complex than the expected “wetter climate in a warmer world” assumption which holds well at the global scale. On the other hand, long-term projections of precipitation may be better than previously thought as major processes seem to be already implemented correctly in general circulation models.
The interplay between geodynamics and flooding drives the dynamics of the inner Okavango Delta (North Botswana)
Authors: Dauteuil Olivier , Jolivet Marc , Murray-Hudson Mike , Barrier laurie , Audran Aziliz , Radenac Aëla
Published: March 2020

The southwestward propagation of the East African Rift System inside the southern African plateau generated the Okavango basin in a strike-slip context. This setup generates one of the largest endoreic ecosystem in Africa: the Okavango Delta alluvial fan. The sedimentary and topography dynamics of that system are driven by both annual flooding and strike-slip geodynamics. To evaluate the impact of ground deformation on the long-term evolution of the Okavango ecosystem, we estimated the 3D strain field from the deformation of a geodetic network composed of 7 dual-frequency GPS semi-permanent stations measured during 4 years. The Okavango basin is a half-graben: its SE edge being limited by a set of normal faults, while the NW limit is bounded by a right-lateral fault. This fault pattern generates strain partitioning with a stretching direction that changes from oblique to parallel to the graben trend and with the highest dilation to the NE and shortening to the SW. Integrating geophysical data, we propose a crustal model describing a strike-slip basin with a normal detachment zone connected to a steep strike-slip shear zone in the lower crust. We show that strain partitioning lead to dilating and shortening domains, which favors water flow toward the NE and progressively restricts water discharge into Lake Ngami, SW of the Delta.

At regional scale, the vertical component of the ground deformation recorded over 10 years reveals annual variations generated by the cyclic flooding, this process acting in addition to the ground deformation induced by the regional geodynamics. A preliminary numerical modeling of the ground flexure induced by the floods constrains the rheological properties of the crust. It highlights two domains with high subsidence limiting a domain with lower subsidence allowing differential water storage.

We conclude that the geodynamic deformation linked to the propagation of the East African Rift into the Okavango half-graben is a key factor controlling the hydrodynamics and ecosystem evolution of the Okavango Delta fan. This control is super-imposed to the effects of variations in sediment and water supply linked to regional climate change. More generally, we show that intra-continental endoreic systems can be highly sensible to low amplitude tectonic deformation.

 