bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Approach for a better exploitation of a 3D seismic on a development field 
Authors: Medjdouba Nasrine , Benaissa Zahia , Annou Sabiha
Published: March 2021

The main hydrocarbon-bearing reservoirover the study area is the lower Triassic Argilo-Gréseux reservoir. The Triassic sand is deposited as fluvial channels and overbank sands with a thickness ranging from 10 to 20 m, lying unconformably on the Paleozoic formations. Lateral and vertical distribution of the sand bodies is challenging which makes their mapping very difficult andnearly impossible with conventional seismic analysis. 

In order to better define the optimum drilling targets, the seismic attribute analysis and reservoir characterization process were performed targeting suchthin reservoir level, analysis of available two seismic vintages of PSTM cubes as well as post and pre stack inversion results were carried out.The combination of various attributes analysis (RMS amplitude, Spectral decomposition, variance, etc.) along with seismic inversion results has helped to clearly identify the channelized feature and its delineation on various horizon slices and geobodies, the results were reviewed and calibrated with reservoir properties at well location and showed remarkable correlation.

Ten development wells have been successfully drilledbased on the seismic analysis study, confirming the efficiency of seismic attribute analysis to predicted channel body geometry.

Keywords: Channel, Attributes, Amplitude, Inversion, Fluvial reservoir.
Real-time regional VTEC modeling based on B-splines using real-time GPS and GLONASS observations
Authors: Erdogan Eren , Goss Andreas , Schmidt Michael , Dettmering Denise , Seitz Florian , Müller Jennifer , Lexen Ernst , Görres Barbara , Kersten Wilhelm F.
Published: March 2021

The project OPTIMAP is at the current stage a joint initiative of BGIC, GSSAC and DGFI-TUM. The development of an operational tool for ionospheric mapping and prediction is the main goal of the project.

The ionosphere is a dispersive medium. Therefore, GNSS signals are refracted while they pass through the ionosphere. The magnitude of the refraction rate depends on the frequencies of the transmitted GNSS signals. The ionospheric disturbance on the GNSS signals paves the way of extracting Vertical Total Electron Content (VTEC) information of the ionosphere.

In OPTIMAP, the representation of the global and regional VTEC signal is based on localizing B-spline basis functions. For global VTEC modeling, polynomial B-splines are employed to represent the latitudinal variations, whereas trigonometric B-splines are used for the longitudinal variations. The regional modeling in OPTIMAP relies on a polynomial B-spline representation for both latitude and longitude.

The VTEC modeling in this study relies on both a global and a regional sequential estimator (Kalman filter) running in a parallel mode. The global VTEC estimator produces VTEC maps based on data from GNSS receiver stations which are mainly part of the global real-time IGS network. The global estimator relies on additional VTEC information obtained from a forecast procedure using ultra-rapid VTEC products. The regional estimator makes use of the VTEC product of the real-time global estimator as background information and generates high-resolution VTEC maps using real-time data from the EUREF Permanent GNSS Network. EUREF provides a network of very dense GNSS receivers distributed alongside Europe.

Carrier phase observations acquired from GPS and GLONASS, which are transmitted in accordance with RTCM standard, are used for real-time regional VTEC modeling. After the acquisition of GNSS data, cycle slips for each satellite-receiver pair are detected, and ionosphere observations are constructed via the linear combination of carrier-phase observations in the data pre-processing step. The unknown B-spline coefficients, as well as the biases for each phase-continuous arc belonging to each receiver-satellite pair, are simultaneously estimated in the Kalman filter.

Within this study, we compare the performance of regional and global VTEC products generated in real-time using the well-known dSTEC analysis.
SAO-QBO Coupling before the 2019 and 2002 Southern Sudden Stratospheric Warmings
Authors: Nordström Viktoria , Seppälä Annika
Published: March 2021

During September 2019 there was a sudden stratospheric warming over Antarctica, which brought disruption to the usually stable winter vortex. The mesospheric winds reversed and temperatures in the stratosphere rose by over 50~K. Whilst this was only the second SSW in the Southern Hemisphere (SH), the other having occurred in 2002, its Northern counterpart experiences about six per decade. Currently, an amplification of atmospheric waves during winter is thought to trigger SSWs. Our understanding, however, remains incomplete, especially with regards to its occurrence in the SH. Here, we investigate the interaction of two equatorial atmospheric modes, the Quasi Biennial Oscillation (QBO) and the Semiannual Oscillation (SAO) during the SH winters of 2019 and 2002. Using MERRA-2 reanalysis data we find that the two modes interact at low latitudes during their easterly phases in the early winter, forming a zero wind line that stretches from the lower stratosphere into the mesosphere. This influences the meridional wave guide, resulting in easterly momentum being deposited in the mesosphere throughout the polar winter, reducing the magnitude of the westerly winds. As the winter progresses these features descend into the stratosphere, until SSW conditions are reached. We find similar behaviour in two other years leading to delayed dynamical disruptions later in the spring. The timing and magnitude of the SAO and the extent of the upper stratospheric easterly QBO signal, that results in the SAO-QBO interaction, was found to be unique in these years, when compared to the years with a similar QBO phase. We propose that this early winter behaviour may be a key physical process in decelerating the mesospheric winds which may precondition the Southern atmosphere for a SSW. Thus the early winter equatorial upper stratosphere-mesosphere together with the polar mesosphere may provide critical early clues to an imminent SH SSW.
The geography of numerical mixing in a suite of global ocean models
Authors: Holmes Ryan , Zika Jan , Griffies Stephen , Hogg Andrew , Kiss Andrew , England Matthew
Published: March 2021

Numerical mixing, the physically spurious diffusion of tracers due to the numerical discretization of advection, is known to contribute to biases in ocean circulation models. However, quantifying numerical mixing is non-trivial, with most studies utilizing specifically targeted experiments in idealized settings. Here, we present a precise method based on water-mass transformation for quantifying numerical mixing, including its spatial structure, that can be applied to any conserved variable in global general circulation ocean models. The method is applied to a suite of global MOM5 ocean-sea ice model simulations with differing grid spacings and sub-grid scale parameterizations. In all configurations numerical mixing drives across-isotherm heat transport of comparable magnitude to that associated with explicitly-parameterized mixing. Numerical mixing is prominent at warm temperatures in the tropical thermocline, where it is sensitive to the vertical diffusivity and resolution. At colder temperatures, numerical mixing is sensitive to the presence of explicit neutral diffusion, suggesting that much of the numerical mixing in these regions acts as a proxy for neutral diffusion when it is explicitly absent. Comparison of equivalent (with respect to vertical resolution and explicit mixing parameters) 1/4-degree and 1/10-degree horizontal resolution configurations shows only a modest enhancement in numerical mixing at the eddy-permitting 1/4-degree resolution. Our results provide a detailed view of numerical mixing in ocean models and pave the way for future improvements in numerical methods.
Using video images to study Haima cold seep bubble plumes
Authors: Zhang Kun , Song Haibin , Wang Hongbin , Gong Yi , Fan Wenhao , Guan Yongxian , Tao Jun , Geng Minghui
Published: March 2021

Cold seep is a widespread geological process mainly caused by hydrocarbon fluid migration. Methane bubble plumes released from cold seeps are often observed at the seafloor. These methane bubbles might be released into the atmosphere and have a huge effect on climate changes. It is of great significance for understanding the fate of these methane bubble plumes.

Many kinds of methods have been used to observe the methane bubble plumes, e.g., acoustical, geochemical, and optical methods. Video imaging is a kind of optical methods widely used in methane bubble plume studies. Compared to other methods, video imaging is a non-intrusive, high-resolution, and quick-collected method. Many studies have estimated bubbles' size, rise velocities, behavior, and the fate of bubbles by analyzing video images manually. However, manual analysis is time-consuming, one dimension, and has not been able to determine temporospatial changes in a two-dimension profile perspective.

In this study, we applied the manual analysis method and the particle image velocimetry (PIV) method to analyze in-situ video image sequences of Haima cold seep bubble plumes, a newly discovered, active cold seep in the Qiongdongnan Basin of the northern South China Sea during 2019. Quantitative and temporospatial change information about the plume flow filed is obtained. The results show that the sizes of bubbles in the plume range from 2.556 ~ 4.624 mm, with a rising velocity of ~ 0.26 m/s. The flux for an individual bubble stream is ~ 94.8 ml/min. The flow velocity field of the bubble plume is consistent with the manual analysis, and it reveals that the bubble plume's flow field is a multiscale turbulent flow field. The bubble plumes are usually V-shaped. Through carrying the adjacent water column, the bubble plumes swell and change rapidly. The direction and velocity of the bubble plume flow change with time, and its streamlines are sinuous. The max velocity of the bubble plume flow field changes at a 6.6 s period cycle.

Although there is some indetermination, our results show that the PIV method is feasible for calculating the bubble plume flow field and that it has some unique advantages, e.g., it is fast, non-invasive, it provides two-dimension temporospatial change images, and it has a high resolution. The images of the bubble plume flow field provide a new perspective to observe the cold seep systems. We hope that this method can be improved and widely applied in cold seep plume studies in the future.
Plate tectonics and Earth System Science
Authors: Müller Dietmar
Published: March 2021

Over the last 25 years the theory of plate tectonics and a growing set of geo-databases have been used to develop global plate models with increasing sophistication, enabled by open-source plate reconstruction software, particularly GPlates. Today’s editable open-access community models include networks of evolving plate boundaries and deforming regions, reflecting the fact that tectonic plates are not always rigid. The theory of plate tectonics was originally developed primarily based on magnetic anomaly and fracture zone data from the ocean basins. As a consequence there has been a focus on applying plate tectonics to modelling the Jurassic to present-day evolution of the Earth based on the record of preserved seafloor, or only modelling the motions of continents at earlier times. Modern plate models are addressing this shortcoming with recently developed technologies built upon the pyGPlates python library, utilising evolving plate boundary topologies to reconstruct entirely destroyed seafloor for the entire Phanerozoic. Uncertainties in these reconstructions are large and can represented with end-member scenarios. These models are paving the way for a multitude of applications aimed at better understanding Earth system evolution, connecting surface processes with the Earth’s mantle via plate tectonics. These models allow us to address questions such as: What are the causes of major perturbations in the interplay between tectonic plate motion and Earth’s deep interior? How do lithospheric deformation, mantle convection driven dynamic topography and climate change together drive regional changes in erosion and sedimentation? How are major perturbations of the plate-mantle system connected to environmental change, biological extinctions and species radiation?
Anomalous measurements at SEP63 IMS station in June 2020: a preliminary forensic approach
Authors: Ottaviano Giuseppe , Rizzo Antonietta , Telloli Chiara , Ubaldini Alberto , Ferrucci Barbara , Padoani Franca
Published: March 2021

In June 2020, the Swedish station SEP63 of the International Monitoring System (IMS) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) recorded anomalous values of a mixture of some fission products and neutron activation products not present in the natural background of the station itself. Some concentration activity values above the statistical range of the station were measured. An online search for any relevant news reports was carried out and atmospheric transport modelling (ATM) conducted to identify the possible source of the emissions and to assess the related source-term. The aim of this work is to sketch out a preliminary forensic approach to characterize the event.
Projected changes in wind wave directional spectra and their impact on coastal processes
Authors: Lobeto Hector , Menendez Melisa , Losada Iñigo J. , Mazzaretto Ottavio
Published: March 2021

The assessment of the projected changes in wave climate due to climate change has been subject of study during the last two decades (Morim et al., 2018), largely due to the severe impacts these changes may have on coastal processes such as flooding and erosion. The wind wave climate is fully described by the sea surface elevation spectrum, which represents the distribution of energy resulting from the contributions of several superimposed waves with different periods and directions. Nevertheless, to this day the standard approach to address the future behavior of wind waves is based on the use of integrated wave parameters (e.g. significant wave height, mean wave period, mean wave direction) as a representation of the full spectrum. In this study, we analyze the changes in wave energy from directional spectra discretized in 24 directions and 32 frequencies in a number of locations distributed across all ocean basins, shedding light on the added value that an assessment based on the full spectrum offers with respect to the standard approach. In addition, the ESTELA method (Pérez et al., 2014) is applied to ease the understanding of the changes obtained in wave energy at the locations of study.

The spectral approach helps to assess the projected change in the energy of each wave system that reach a specific location. Results demonstrate that the use of integrated wave parameters can mask important information about the sign, magnitude and uncertainty of the actual projected changes in mean wave climate due to the offset of the expected variations in the different wave systems that integrate the spectrum. It is especially relevant at locations where an increase in the wave period or wave energy is hidden by the application of the standard approach, as these parameters are proven to play a key role in coastal processes. In addition, we reach relevant conclusions about the future behavior of swell systems. For instance, a robust increase in the energy carried by swells generated below 40°S can be observed in every ocean basin and both hemispheres, even beyond 30°N. Similarly, a decrease in the energy carried by northern swells can be observed close to the equator.
The CIMR mission and its unique capabilities for soil moisture sensing
Authors: Piles Maria , Fernandez-Moran Roberto , Gómez-Chova Luis , Camps-Valls Gustau , Entekhabi Dara , Baur Martin , Jagdhuber Thomas , Wigneron Jean-Pierre , Prigent Catherine , Donlon Craig
Published: March 2021

The Copernicus Imaging Microwave Radiometer (CIMR) mission is currently being developed as a High Priority Copernicus Mission to support the Integrated European Policy for the Arctic. Due to its measurement characteristics, CIMR has exciting capabilities to enable a unique set of land surface products and science applications at a global scale. These characteristics go beyond what previous microwave radiometers (e.g. AMSR series, SMAP and SMOS) provide, and therefore allow for entirely new approaches to the estimation of bio-geophysical products from brightness temperature observations. Most notably, CIMR channels (L-,C-,X-,Ka-,Ku-bands) are very well fit for the simultaneous retrieval of soil moisture and vegetation properties, like biomass and moisture of different plant components such as leaves, stems or trunks. Also, the distinct spatial resolution of each frequency band allows for the development of approaches to cascade information and obtain these properties at multiple spatial scales. From a temporal perspective, CIMR has a higher revisit time than previous L-band missions dedicated to soil moisture monitoring (about 1 day global, sub-daily at the poles). This improved temporal resolution could allow resolving critical time scales of water processes, which is relevant to better model and understand land-atmosphere exchanges and feedbacks. In this presentation, new opportunities for soil moisture remote sensing made possible by the CIMR mission, as well as synergies and cross-sensor opportunities will be discussed.  
Effects of mean sea level rise and tidal flat growth on tides and storm surge events in the Elbe estuary
Authors: Mahavadi Tara , Rudolph Elisabeth , Seiffert Rita , Winkel Norbert
Published: March 2021

Future mean sea level rise will influence tidal dynamics and storm surge events in estuaries. The bathymetry in estuaries and coastal areas will also be affected by mean sea level rise, since it is in a morphodynamic equilibrium with hydrodynamic forces. Tidal flats, which are an important component of coastal protection, will grow to a certain extent with mean sea level rise in case of sufficient sediment availability.

With the help of a highly resolved hydrodynamic-numerical model of the German Bight (North Sea), we analyse the potential influence of mean sea level rise and vertical growth of tidal flats on tidal dynamics and storm surge events in the Elbe estuary.

The results show an increase of tidal amplitude and storm surge water levels due to mean sea level rise. A bathymetric rise of tidal flats in the German Bight and the mouth of the Elbe estuary leads to a decrease in storm surge water level and tidal amplitude compared to the scenario with sole mean sea level rise without a change in bathymetry. Further analyses show, how geometric parameters of the Elbe estuary are changing due to mean sea level rise and tidal flat growth. These changes in geometry influence tidal dynamics and can therefore be an explanation for the observed changes in tidal amplitude and storm surge water levels.

These findings enable a better understanding of future changes in the Elbe estuary and support coastal managers in decision making processes concerning adaptation options to reduce the impacts of climate change.
Effects of optimisation parameters on data-driven magnetofrictional modelling 
Authors: Kumari Anshu , Price Daniel , Kilpua Emilia , Pomoell Jens , Daei Farhad
Published: March 2021

The solar coronal magnetic field plays an important role in the formation, evolution, and dynamics of small and large-scale structures in the corona. Estimation of the coronal magnetic field, the ultimate driver of space weather, particularly in the ‘low’ and ‘middle’ corona, is presently limited due to practical difficulties. Data-driven time-dependent magnetofrictional modelling (TMFM) of active region magnetic fields has been proven as a tool to observe and study the corona. In this work, we present a detailed study of data-driven TMFM of active region 12473 to trace the early evolution of the flux rope related to the coronal mass ejection that occurred on 28 December 2015. Non-inductive electric field component in the photosphere is critical for energizing and introducing twist to the coronal magnetic field, thereby allowing unstable configurations to be formed. We estimate this component using an approach based on optimizing the injection of magnetic energy. We study the effects of these optimisation parameters on the data driven coronal simulations. By varying the free optimisation parameters, we explore the changes in flux rope formation and their early evolution, as well other parameters, e.g. axial flux, magnetic field magnitude.
Selecting climate projections for services: the DRIAS-2020 dataset
Authors: Corre Lola , Somot Samuel , Soubeyroux Jean-Michel , Bernus Sébastien , Drouin Agathe , Dubuisson Brigitte , Etchevers Pierre , Gouget Viviane , Josse Patrick , Kerdoncuff Maryvonne , Samacoits Raphaëlle , Tocquer Flore , Pagé Christian , Ribes Aurélien , Vautard Robert
Published: March 2021

The French National Climate Service “Drias, futures of climate” was launched in 2012, as a response of the French scientific community to society’s need for climatic information. It is mainly composed of a website that provides easy access to the best available climate data to characterize climate change over France. Latest advances developed in 2020 include the availability of a new set of regional climate scenarios corrected by a quantile-mapping based method with correction depending on the weather regime. As for the previous set, the climate projections are based on the EURO-CORDEX ensemble, whose contents have been greatly enriched over the past years. Singular effort was done to build a robust and synthetic set that well represents the uncertainties of climate change over France. The different criteria defined to select the simulations will be presented, and the range of the projected climate change will be examined, with respect to larger ensembles.

 
Projecting 21st century GrIS surface melt using artificial neural networks
Authors: Sellevold Raymond , Vizcaino Miren
Published: March 2021

Accelerated surface melt of the Greenland ice sheet (GrIS) is currently a large contributor to sea level rise, and the primary process of GrIS mass loss. Projections of future GrIS melt are limited by the lack of explicit melt calculations within most global climate models and the high computational cost of dynamical downscaling with regional models. To translate global climate evolution to GrIS surface melt, we train artificial neural networks (ANNs) with the output of the explicit melt calculation of the Community Earth System Model 2.1 (CESM2). ANNs are well suited for this task, as they are capable of learning complex, non-linear relationships, and they are fast to run.

Our results show that the ANNs accurately project GrIS surface melt when evaluated against regional climate simulations. Further, the ANNs recognize patterns already established in litterature as important for surface melt, and use bases the projections on these patterns. Using the global climate simulations from the CMIP6 archive, the ANNs project a GrIS surface melt increase ranging from 414 Gt yr-1 to 1,378 Gt yr-1 by the end of the 21st century. The main source of projection uncertainty throughout the 21st century is due to the spread in the models’ climate sensitivity.
Climate changes across Oceanic Anoxic Event 1a: new data from the Boreal realm
Authors: Bodin Stephane , Blok Carlette , Ineson Jon , Anderskouv Kresten , Fantasia Alicia , Sheldon Emma , Thibault Nicolas , Adatte Thierry
Published: March 2021

Our understanding of the climatic evolution during the early Cretaceous in general, and the Oceanic Anoxic Event 1a (OAE-1a) in peculiar, is widely derived from the investigation of Tethyan localities, leaving large uncertainties about their significance on a global scale. In this study, we have performed high-resolution clay-mineral assemblage analyses in the upper Hauterivian to lower Aptian of the North Jens-1 core, located in the Danish central graben that was part of the Boreal realm. High amount of detrital Kaolinite is observed throughout the core, indicating the presence of a local, kaolinite-rich source. A long-term decline in Kaolinite content is occurring from the lower Hauterivian to the lowermost, pre-OAE-1a Aptian, followed by a sharp rise within the OAE-1a. This trend is similar to the one observed in the Tethyan realm, indicating a supra-regional climatic evolution from humid conditions in the late Hauterivian toward drier conditions in the latest Barremian – earliest Aptian, followed by renewed humid conditions during the unfolding of OAE-1a. Precise timing of climate change during the OAE-1a differs however in between the Tethyan and Boreal realm. Shift toward humid conditions coincides hence with the onset of OAE-1a (segment C3) in the Tethyan realm, followed by a return to drier conditions in the second half of OAE-1a. In the Boreal realm, the onset of OAE-1a is characterized by a relatively dry climate, followed by the installation of humid climate during the mid-OAE-1a (segments C4-C5) that persists through the remainder of the early Aptian. Across latitudinal belts, there is thus a non-linear change in precipitation pattern during the unfolding of OAE-1a. Similar observations have been made for other OAEs, suggesting more complex weathering feedback mechanism during hyperthermal events than generally assumed.
Deep Learning based assessment of groundwater level development in Germany until 2100
Authors: Wunsch Andreas , Liesch Tanja , Broda Stefan
Published: March 2021

Clear signs of climate stress on groundwater resources have been observed in recent years even in generally water-rich regions such as Germany. Severe droughts, resulting in decreased groundwater recharge, led to declining groundwater levels in many regions and even local drinking water shortages have occurred in past summers. We investigate how climate change will directly influence the groundwater resources in Germany until the year 2100. For this purpose, we use a machine learning groundwater level forecasting framework, based on Convolutional Neural Networks, which has already proven its suitability in modelling groundwater levels. We predict groundwater levels on more than 120 wells distributed over the entire area of Germany that showed strong reactions to meteorological signals in the past. The inputs are derived from the RCP8.5 scenario of six climate models, pre-selected and pre-processed by the German Meteorological Service, thus representing large parts of the range of the expected change in the next 80 years. Our models are based on precipitation and temperature and are carefully evaluated in the past and only wells with models reaching high forecasting skill scores are included in our study. We only consider natural climate change effects based on meteorological changes, while highly uncertain human factors, such as increased groundwater abstraction or irrigation effects, remain unconsidered due to a lack of reliable input data. We can show significant (p<0.05) declining groundwater levels for a large majority of the considered wells, however, at the same time we interestingly observe the opposite behaviour for a small portion of the considered locations. Further, we show mostly strong increasing variability, thus an increasing number of extreme groundwater events. The spatial patterns of all observed changes reveal stronger decreasing groundwater levels especially in the northern and eastern part of Germany, emphasizing the already existing decreasing trends in these regions
Global in-situ cloud phase observations during the airborne Atmospheric Tomography mission and A-LIFE field experiment
Authors: Dollner Maximilian , Gasteiger Josef , Schöberl Manuel , Diskin Glenn , Bui T. Paul , Brock Charles A. , Weinzierl Bernadett
Published: March 2021

Clouds are an important contributor to the uncertainty of future climate predictions, partly because cloud microphysical processes are still not fully understood. Interhemispheric observations, providing a dataset to investigate these cloud microphysical processes, are surprisingly rare - in particular observations using the same instrumentation on a global scale.

Between 2016 and 2018, the ATom (Atmospheric Tomography; 2016-2018) mission and the A-LIFE (Absorbing aerosol layers in a changing climate: aging, lifetime and dynamics; 2017) field experiment performed extensive airborne in-situ measurements of aerosol and cloud microphysical properties in the atmosphere up to approx. 13km altitude on a global scale. Profiling of the remote atmosphere over the Pacific and Atlantic Oceans from about 80°N to 86°S during ATom and systematic sampling of the region in the Mediterranean during A-LIFE provides a combined dataset of nearly 60h of measurements inside clouds.

We developed a novel cloudindicator algorithm, which utilizes measurements of a second-generation Cloud, Aerosol and Precipitation Spectrometer (CAPS, Droplet Measurement Technologies), relative humidity and temperature. It automatically detects clouds and classifies them according to their cloud phase.

In this study we present the novel cloudindicator algorithm and the combined dataset of ATom and A-LIFE global scale in-situ cloud observations. Furthermore, we show results of the cloud phase analysis of the extensive dataset.
New sustainable mortars for stone restoration in the context of climate change
Authors: Diaz-Basteris Jose
Published: March 2021

Restoration mortars are a designated group of products made to repair damaged masonry. They must be compatible with the former support of stones and bricks, and protect original materials from environmental agents; aesthetical and historic aspects must not be neglected. 

To improve the ecological footprint of the restoration mortars while keeping their efficiency, we have tested several combinations of lime with aggregates and additives. Recycled and natural materials were used as additives such as pinecone resin, semi-milled cones of pine, milled glass waste, brick production residue.

For research purposes different physical properties have been measured in prepared mortars: porosity, density, capillarity absorption, moisture absorption, water vapour permeability. We have also tested the mechanical properties and the P and S waves velocities (from which dynamic Young's modulus and Poisson’s ratio were inferred). The durability of mortars has been estimated by salt crystallization and frost/thaw cycles.

The life cycle analysis (LCA) of such mortars allows us to understand the carbon footprint of each manufacturing process. Considering this we selected the raw materials, from an environmental and commercial point of view, to produce mortars fulfilling sustainability requirements. As a result, the developed mortars are compatible with aged stones, minimize environmental impact, and use minimum natural resources.

 Twenty mortar formulations with three different types of limes (NHL5, NHL3.5, CL90) and two different aggregates (siliceous and calcareous) have been studied using the LCA. Currently, five new formulations are being selected to be tested on Euville limestone. Adhesive strength (James Bond test), and physical properties will be measured on these mortars. 
Relative control of bedrock roughness versus topography on global glacier bed friction
Authors: Gagliardini Olivier , Gillet-Chaulet Fabien , Gimbert Florent
Published: March 2021

Friction at the base of ice-sheets has been shown to be one of the largest uncertainty of model projections for the contribution of ice-sheet to future sea level rise. On hard beds, most of the apparent friction is the result of ice flowing over the bumps that have a size smaller than described by the grid resolution of ice-sheet models. To account for this friction, the classical approach is to replace this under resolved roughness by an ad-hoc friction law. In an imaginary world of unlimited computing resource and highly resolved bedrock DEM, one should solve for all bed roughnesses assuming pure sliding at the bedrock-ice interface. If such solutions are not affordable at the scale of an ice-sheet or even at the scale of a glacier, the effect of small bumps can be inferred using synthetical periodic geometry. In this presentation,  beds are constructed using the superposition of up to five bed geometries made of sinusoidal bumps of decreasing wavelength and amplitudes. The contribution to the total friction of all five beds is evaluated by inverse methods using the most resolved solution as observation. It is shown that small features of few meters can contribute up to almost half of the total friction, depending on the wavelengths and amplitudes distribution. This work also confirms that the basal friction inferred using inverse method  is very sensitive to how the bed topography is described by the model grid, and therefore depends on the size of the model grid itself. 
Evaluating temperature extremes in CMIP6 simulations using statistically proper evaluation methods
Authors: Thorarinsdottir Thordis , Sillmann Jana , Haugen Marion , Gissibl Nadine , Sandstad Marit
Published: March 2021

Reliable projections of extremes in near-surface air temperature (SAT) by climate models become more and more important as global warming is leading to significant increases in the hottest days and decreases in coldest nights around the world with considerable impacts on various sectors, such as agriculture, health and tourism.

Climate model evaluation has traditionally been performed by comparing summary statistics that are derived from simulated model output and corresponding observed quantities using, for instance, the root mean squared error (RMSE) or mean bias as also used in the model evaluation chapter of the fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5). Both RMSE and mean bias compare averages over time and/or space, ignoring the variability, or the uncertainty, in the underlying values. Particularly when interested in the evaluation of climate extremes, climate models should be evaluated by comparing the probability distribution of model output to the corresponding distribution of observed data.

To address this shortcoming, we use the integrated quadratic distance (IQD) to compare distributions of simulated indices to the corresponding distributions from a data product. The IQD is the proper divergence associated with the proper continuous ranked probability score (CRPS) as it fulfills essential decision-theoretic properties for ranking competing models and testing equality in performance, while also assessing the full distribution.

The IQD is applied to evaluate CMIP5 and CMIP6 simulations of monthly maximum (TXx) and minimum near-surface air temperature (TNn) over the data-dense regions Europe and North America against both observational and reanalysis datasets. There is not a notable difference between the model generations CMIP5 and CMIP6 when the model simulations are compared against the observational dataset HadEX2. However, the CMIP6 models show a better agreement with the reanalysis ERA5 than CMIP5 models, with a few exceptions. Overall, the climate models show higher skill when compared against ERA5 than when compared against HadEX2. While the model rankings vary with region, season and index, the model evaluation is robust against changes in the grid resolution considered in the analysis.
Upper crustal structure at the KTB drilling site from ambient noise tomography
Authors: Qorbani Ehsan , Bianchi Irene , Kolínský Petr , Zigone Dimitri , Bokelmann Goetz
Published: March 2021

In this study, we show results from ambient noise tomography at the KTB drilling site, Germany. The Continental Deep Drilling Project, or ‘Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschland’ (KTB) is at the northwestern edge of the Bohemian Massif and is located on the Variscan belt of Europe. During the KTB project crustal rocks have been drilled down to 9 km depth and several active seismic studies have been performed in the surrounding. The KTB area therefore presents an ideal test area for testing and verifying the potential resolution of passive seismic techniques. The aim of this study is to present a new shear-wave velocity model of the area while comparing the results to the previous velocity models and hints for anisotropy depicted by former passive and active seismological studies. We use a unique data set composed of two years of continuous data recorded at nine 3-component temporary stations installed from July 2012 to July 2014 located on top and vicinity of the drilling site. Moreover, we included a number of permanent stations in the region in order to improve the path coverage and density. We present here a new velocity model of the upper crust of the area, which shows velocity variations at short scales that correlate well with geology in the region.
WALIS - Towards a global database of Last Interglacial sea-level proxies.
Authors: Rovere Alessio , Ryan Deirdre , Vacchi Matteo , Simms Alexander , Dutton Andrea , Murray-Wallace Colin
Published: March 2021

The standardization of geological data, and their compilation into geodatabases, is essential to allow more coherent regional and global analyses. In sea-level studies, the compilation of databases containing details on geological paleo sea-level proxies has been the subject of decades of work. This was largely spearheaded by the community working on Holocene timescales. While several attempts were also made to compile data from older interglacials, a truly comprehensive approach was missing. Here, we present the ongoing efforts directed to create the World Atlas of Last Interglacial Shorelines (WALIS), a project spearheaded by the PALSEA (PAGES/INQUA) community and funded by the European Research Council (ERC StG 802414). The project aims at building a sea-level database centered on the Last Interglacial (Marine Isotope Stage 5e, 125 ka), a period of time considered as an "imperfect analog" for a future warmer climate. The database is composed of 17 tables embedded into a mySQL framework with a total of more than 500 single fields to describe several properties related to paleo sea-level proxies, dated samples and metadata. In this presentation, we will show the first results of the global compilation, which includes nearly 2000 data points and will discuss its relevance in answering some of the most pressing questions related to sea-level changes in past warmer worlds. 
Fired clay from Neolithic houses – the role of past environment revealed in mineral magnetic properties
Authors: Jordanova Neli , Jordanova Diana , Lesigyarski Deyan , Kostadinova-Avramova Maria
Published: March 2021

Human behavior and especially the use of fire increasingly influence our environment during the Anthropocene epoch. Balkan Peninsula is on the road of the ancient human dispersal during the Neolithic period. Burnt Neolithic remains are often related to ancient houses which ended their existence as a result of extensive fire. Materials from burnt clay remains from house destructions originating from 18 Neolithic sites from Bulgaria were studied using rock magnetism. Mineral magnetic studies and equivalent firing temperature estimates were carried out. The aim of the study was to explore the magnetic signature of fired clay materials in relation to the most important environmental factors. The main magnetic minerals identified were magnetite, maghemite and hematite, in several cases also epsilon-Fe2O3. Magnetic susceptibility enhancement is dependent on the raw clay mineralogy and the firing intensity, being higher for sites developed on loess materials. Sites located in river valleys from South Bulgaria show lower susceptibility enhancement. Magnetic susceptibility  and percent frequency dependent magnetic susceptibility at site level were considered in relation to the climatic conditions during the Neolithic as revealed by anthracological studies already published for the study region. Firing temperature estimates, comprising 198 single determinations in total, vary in the range 580 – 1050°C across the sites. Estimated average firing temperatures at site’s level showed higher values in Early Neolithic sites (Tfire average=815°C) as compared to Late Neolithic ones (Tfire average = 746°C and 713°C). Several possible hypotheses for the trend observed are considered: difference in climate regimes across the territory leading to different “fire weather”; difference in the vegetation fuel used in house construction; and intentional burning of Early Neolithic houses. This study is financially supported by the project KP-06-COST/2, funded by the Bulgarian National Science Fund.
Laser Ranging Interferometer on GRACE Follow-On: Current Status
Authors: Müller Vitali , Misfeldt Malte , Müller Laura , Wegener Henry , Heinzel Gerhard
Published: March 2021

The GRACE Follow-On satellites were launched on 22nd May 2018 to continue the measurement of Earth’s gravity field from the GRACE satellites (2002-2017). A few weeks later, an inter-satellite laser link was established with the novel Laser Ranging Interferometer (LRI), which offers an additional measurement of the inter-satellite range next to the one provided by the conventional microwave ranging instrument. The LRI is the first optical interferometer in space between orbiters, which has demonstrated to measure distance variations with a noise below 1 nm/√Hz at Fourier frequencies around 1 Hz, well below the requirement of 80 nm/√Hz. In this talk, we provide an overview on the LRI, present the current status of the instrument and show results regarding the characterization of the instrument. We will address impulse events that are apparent in the accelerometer and LRI range acceleration data, most of which are expected to be micro-meteorites. Other short-term disturbances in the ranging data will be addressed as well. We conclude with some learned lessons and potential modifications of the interferometry for future geodetic missions.
Geochemistry of Geological Hydrogen Storage in Sandstone Reservoirs
Authors: Hassanpouryouzband Aliakbar , Edlmann Katriona , Wilkinson Mark
Published: March 2021

To enable a fast transition of the global energy sector towards operation with 100% renewable and clean energy technology, the geological storage of hydrogen in depleted gas fields or salt caverns has been considered as a strong candidate for the future energy storage required for limiting global warming to well below 2 °C, as agreed under the Paris Agreement. As such, understanding the impact of injected hydrogen on the geochemical equilibrium in these storage reservoirs is critical. Here, using our bespoke high pressure/temperature batch reaction vessels we investigate the potential effects of hydrogen injection into 3 different sandstones reservoirs.  These experiments were conducted at reservoir temperature and at different injection pressures from 1 to 20 MPa with salinities from 0 to 10 weight% over different time periods from 1 to 8 weeks.  Our experiments reveal that there is no hydrogen-associated geochemical reaction for the selected sandstones. Although changing reservoir pressure slightly affected the mineral dissolution equilibria at ppm level for hydrogen injection scenarios, the fluctuations of mineral dissolution in water associated with pressure change have a negligible influence on the efficiency of geological hydrogen storage.  Therefore, based on the analysis of water chemistry before and after the mentioned experiments, we demonstrate that from geochemical point of view geological storage of hydrogen in these sandstone reservoirs is safe and we don’t expect any hydrogen loss due to geochemical reactions. 
Flux tubes and energetic particles in Parker Solar Probe orbit 5: magnetic helicity - PVI method and ISOIS observations
Authors: Pecora Francesco , Servidio Sergio , Greco Antonella , Bale Stuart D. , McComas David J. , Joyce Colin J. , Matthaeus William H.
Published: March 2021

Plasma turbulence can be viewed as a magnetic landscape populated by large- and small-scale coherent structures, consisting notionally of magnetic flux tubes and their boundaries. Such structures exist over a wide range of scales and exhibit diverse morphology and plasma properties.  Moreover, interactions of particles with turbulence may involve temporary trapping in, as well as exclusion from, certain regions of space, generally controlled by the topology and connectivity of the magnetic field.  In some cases, such as SEP "dropouts'' the influence of the magnetic structure is dramatic; in other cases, it is more subtle, as in edge effects in SEP confinement. With Parker Solar Probe now closer to the sun than any previous mission, novel opportunities are available for examination of the relationship between magnetic flux structures and energetic particle populations. 

We present a method that is able to characterize both the large- and small-scale structures of the turbulent solar wind, based on the combined use of a filtered magnetic helicity (Hm) and the partial variance of increments (PVI). The synergistic combination with energetic particle measurements suggests whether these populations are either trapped within or excluded from the helical structure.

This simple, single-spacecraft technique exploits the natural tendency of flux tubes to assume a cylindrical symmetry of the magnetic field about a central axis. Moreover, large helical magnetic tubes might be separated by small-scale magnetic reconnection events (current sheets) and present magnetic discontinuity with the ambient solar wind. The method was first validated via direct numerical simulations of plasma turbulence and then applied to data from the Parker Solar Probe (PSP) mission. In particular, ISOIS energetic particle (EP) measurements along with FIELDS magnetic field measurements and SWEAP plasma moments, are enabling characterization of observations of EPs closer to their sources than ever before.
 
This novel analysis, combining Hm and PVI methods, reveals that a large number of flux tubes populate the solar wind and continuously merge in contact regions where magnetic reconnection and particle acceleration may occur. Moreover, the detection of boundaries, correlated with high-energy particle measurements, gives more insights into the nature of such helical structures as "excluding barriers'' suggesting a strong link between particle properties and fields topology. This research is partially supported by the Parker Solar Probe project. 