bluuebunny/crossref_metadata_2025 huggingface dataset:
Producing fractures with a 3D-printer for flow experiments – the price to pay for the easy way out
Authors: Kröhn Klaus-Peter , Kröhn Michael
Published: March 2020

Recently, the technology of 3D-printing has been applied to literally look into flow and transport processes in fractures and fracture system using transparent material for printing. Preparing some own experiments with printed fractures it was noticed, though, that very little is known about dimensional accuracy of printed components. There are indications that fractures, as a rule of thumb, require an aperture of at least ten times of the printing resolution that is claimed by the manufacturer in order to be water conducting at all. Seemingly little attention has also been paid to the roughness of the printed fracture surfaces that would affect flow in an allegedly smooth plane fracture. Furthermore, the majority of resins  that are used for 3D-printing take up water which leads to swelling of the printed components. This has an up to now unknown influence on fracture aperture.

For these reasons a list of simple tests has been developed to check and compare the geometrical and physical properties of printed components right after production and under subsequent influence of water. Varied were printers, materials, sample orientations, sample geometries and postprocessing parameters like curing time. The dimensions of dry and wet samples were meticulously measured. Exemplarily on one sample, also the water uptake dynamics under the influence of water vapour under different degrees of saturation have been determined. A further test concerned the penetration depth of water.

The results form a little data base. Sample geometries and testing methods have been kept simple deliberately to allow for a meaningful comparison, not only for ourselves but also for other potential testing parties that might want to contribute data in exchange for the whole data base.

The major general conclusion that can be drawn from the tests is that contact time of 3D-prints with water should be minimised if dimensional accuracy is of importance. Tests concerning fracture flow in printed samples thus need to be performed as quickly as possible.
ULF waves and their influence on radiation belt dynamics in Earth's magnetosphere
Authors: Rankin Robert , Degeling Alexander
Published: March 2020

Recent observations from the Van Allen Probes mission have established that Pc3-5 ultra-low-frequency (ULF) waves can energize ions and electrons via drift-resonance and drift-bounce resonance. The extent to which these waves contribute to the space weather of the belts is relatively poorly understood and requires sophisticated modelling and characterization of the dominant wave modes that arise in the development and recovery phase of geomagnetic storms. Despite more than four decades of observations and theoretical analysis of ULF waves, there is no framework for accurately assessing the global distribution of ULF waves and their influence on the ring current. 
In this presentation, we describe a new global model of ULF waves that incorporates non-dipolar geomagnetic fields. The model is constrained using the GCPM of cold plasma density model and a specification of the ionosphere using the IRI and MSIS models. An algorithm is applied to adjust the initial plasma state to a quasi-static equilibrium that is then driven by a global convection electric field and ULF wave source. For specific observations by the Van Allen Probes and ARASE mission, the effect of these ULF waves on radiation belt ions and electrons is evaluated utilizing test-particle methodology and Liouville's theorem, which enables the phase space density to be followed and compared one-for-one with the satellite observations.  
Intercomparison of PBL height estimations in the framework of HyMeX-SOP1
Authors: Summa Donato , Di Girolamo Paolo , De Rosa Benedetto , Madonna Fabio
Published: March 2020

This paper reports results from an inter-comparison effort involving different sensors/techniques used to measure the Planetary Boundary Layer (PBL) height. The effort took place in the framework of the first Special Observing Period of the Hydrological cycle in the Mediterranean Experiment. The PBL is directly influenced by the Earth's surface, responding to combined action of mechanical and thermal forcing factors. The evolution of the PBL structure and height has important meteorological role. Accurate measurements of the PBL height are important to validate forecast models or support their development through the improvement of the physical representations embedded in, for example, their boundary layer turbulence and shallow convection parameterizations. Elastic backscatter signals and rotational Raman signals collected by lidar systems can be used to characterize the PBL height and its internal structure.  In the present research effort, this technique is compared with measurements from a co-located wind profiler and  a  potential temperature computed from radio-sounding system. Comparisons involving the different sensors will be discussed at the conference.
Automated high resolution rain water sampler for stable water isotope monitoring
Authors: Andermann Christoff , Queißer Torsten , Reich Markus , Puri Bijaya , Hovius Niels , Sachse Dirk
Published: March 2020

With global climate change, one of the largest short-term threats to our societies comes from changes in the hydro-meteorological cycle: droughts, flooding and potentially increasing extreme rain events may have far greater direct impact on humans than rising temperatures alone. These changes often have sever consequences and widespread impact on society and ecosystems, yet they are difficult to track, trace and measure in order to fully understand the underlying process of delivering moisture and recharging water reservoirs. Only through the comprehensive monitoring of precipitation waters in space and time can we improve our process understanding and better predict the direction and magnitude of future hydro-meteorological changes, in particular on regional spatial scales. However, no commercial automated sampling solution exists, which fulfills the quality criteria for sophisticated hydrochemical water analysis. Here, we present an advanced prototype automatic precipitation water sampler for stable water isotope analysis of precipitation. The device is designed to be highly autonomous and robust for campaign deployment in harsh remote areas and fulfills the high demands on sampling and storage for isotope analysis (i.e. sealing of samples from atmospheric influences, no contamination and preservation of the sample material). The sampling device is portable, has low power consumption and a real-time adaptable sampling protocol strategy, and can be maintained at distance without any need to visit the location. Furthermore, the obtained water samples are not restricted to isotope analysis but can be used for any type of environmental water analysis. The current configuration can obtain 165 discrete rainwater samples with a minimum timely resolution of 5min or volume wise 2mm of rainfall. Our lab tests with dyed waters and waters with strongly differing isotopic signature demonstrate that the device can obtain, store and conserve samples without cross contamination over long periods of time. The device has been tested so far under several conditions, e.g. heavy summer thunderstorms with more than 50mm/24h of rainfall, sustained winter rainfall and in cold conditions involving melting of snow. This automated rainwater sampler provides an economic and sophisticated technological solution for monitoring moisture pathways and water transfer processes with the analytical quality of laboratory standard measurements on a new level of temporal and spatial resolution.
Retrieval of chlorine dioxide columns from Sentinel-5p observations
Authors: Meier Andreas Carlos , Richter Andreas , Pinardi Gaia , Van Roozendael Michel , Burrows John Philip
Published: March 2020

The Sentinel-5-precursor (S5p) satellite with the TROPOMI payload was launched on 13 October 2017. It is part of the European Copernicus program and provides a set of operational products of atmospheric constituents related to air quality and climate change with almost daily global coverage. The good signal to noise ratio of the instrument enables precise measurements despite the fine spatial resolution of 3.5 x 5.5 km2. 

The ESA S5p+ Innovation activity aims at extending the list of S5p products with scientific products, which are not yet part of the operational processor, to exploit the potential of the Sentinel-5p mission’s capabilities beyond its primary objectives. The retrieval of chlorine dioxide (OClO) from S5p is among the seven funded sub projects. Chlorine dioxide is an indicator for chlorine activation in the stratosphere and thus of importance for the understanding of stratospheric ozone chemistry, in particular in the polar vortex. Chlorine dioxide was retrieved from heritage instruments (GOME, SCIAMACHY, GOME2, OMI) and the S5p OClO product will act as a continuation of these time-series.

Here we present the current status of the IUP-Bremen S5p OClO product developed within the ESA S5p+ Innovation framework. The new S5p product will be put into context with products from previous and current (e.g. GOME-2c) satellite missions as well as ground-based measurements used for validation.
Non-Parametric Bayesian Networks for Hydrological Studies
Authors: Ragno Elisa , Hrachowitz Markus , Morales-Nápoles Oswaldo
Published: March 2020

Non-Parametric Bayesian Networks (NPBNs) are graphical tools for statistical inference when new information become available. They have been widely used for reliability analysis and risk assessment. However, few hydrological applications can be found in the literature. Consequently, we explore the potential of NPBNs for maximum river discharge estimation by investigating a number of catchments with contrasting climate across the United States. Different networks schematizing river discharge generation processes at the catchment scale are built and analysed. Hydro-meteorological forcings and catchment's attributes are retrieved from Catchment Attributes for Large-Sample Studies (CAMELS). We highlight the benefits but also the challenges encountered in the application of NPBNs for river discharge estimation. Finally, we provide insights on how to overcome some of the difficulties met.
How to inform decision making under uncertainty? Quantifying and evaluating different sources of uncertainty in environmental modelling
Authors: Jackisch Conrad , Schibalski Anett , Schröder Boris
Published: March 2020

Adaptation to environmental changes requires decision making under uncertainty. Providing forecasts of the potential impact of different management options is a common task for environmental modellers. However, we rarely succeed in conveying uncertainties as relevant information to distinguish management options regarding their expected value and its uncertainty. Quite to the contrary, the reality in the modelling of complex systems under climate change often leads to similar mean values and broad uncertainty bands. Both may irritate users and even lead to indecision and inaction despite an urgent call for action.

In the inter- and transdisciplinary project RUINS (Risk, Uncertainty and Insurance under Climate Change. Coastal Land Management on the German North Sea), we address a region that is sensitive to changes in relative sea level, weather patterns and land-use practices. We develop methods to quantify the uncertainty of adaptation measures through the chain of models for climate, hydrology and landscape management. The aim is to provide tools for the evaluation of forecasted effects of management options, where uncertainty itself is considered an evaluation criterion.

We will present examples to point out pitfalls and potentials of uncertainty quantification in environmental model forecasting for management decision making: (i) we highlight different sources and different kinds of uncertainty with an example of agricultural production; (ii) we address trade-offs between expected wind power production and the security of its provision; moreover, (iii) we highlight the role of temporal data resolution and capacity of drainage structures in the assessment of flood protection during extreme rain events.
Projected response of Arabian sea Oxygen minimum zone to climate change: Insights from a set of downscaled experiments
Authors: Vallivattathillam Parvathi , Lachkar Zouhair , Levy Marina , Smith Shafer
Published: March 2020

The land-locked northern boundary and seasonal high productivity in the Arabian sea (AS) leads to the formation and the maintenance of one of the most intense and thickest open ocean oxygen minimum zones (OMZ) there. Earlier studies based on both observation and model sensitivity experiments have reported that this perennial OMZ is highly sensitive to the strength of the monsoonal circulation and surface heating. Model simulations from the fifth phase of Coupled Model Intercomparison project (CMIP5) indicate significant changes in the Indian monsoonal circulation and the atmospheric heat fluxes under climate change. However, the future projection of AS OMZ under climate change remains largely uncertain and ill-understood. This is mainly due to a poor representation of the AS OMZ in the CMIP5 simulations and an important spread in their future oxygen projections for the region. Here we explore how downscaling CMIP5 global simulations with a high-resolution configuration of the Regional Ocean Modeling System (ROMS) model coupled to a nitrogen-based NPZD ecosystem model can help improving the representation of the AS OMZ and reduce the spread in CMIP5 projections. To this end, we performed a climatological “reference” simulation, i.e., the control simulation, where ROMS is forced with observed atmospheric and lateral boundary conditions, and a set of corresponding downscaled sensitivity experiment where ROMS is forced with atmospheric and lateral boundary conditions derived from global CMIP5 simulations. For the downscaling experiment, we chose two best performing models from the CMIP5 database based on their skill in simulating the present day (historical) climatology. The control simulation has been extensively validated against the observations for its skill in simulating the physical and biogeochemical variables. We explore the sensitivity of the downscaled oxygen distribution and OMZ to the regional model setup by varying the model resolution from 1/3deg to 1/12deg and expanding the model domain from a small AS-limited domain to one encompassing the full Indian Ocean. We show that the downscaled experiments improve the representation of different classes of oxygen (Oxic - O2 > 60mmol/l; Hypoxic - 60mmol/l >= O2 > 4mmol/l; and the Suboxic  - 4 mmol/l > O2 > 0 mmol/l) within the 0-1500m depth range. In particular, the downscaled experiments simulate a much smaller fraction of suboxic waters relative to hypoxic and oxic fractions, in agreement with observations.

 
Modelling lithosphere dynamics with robust rheological implementations: Towards 3D
Authors: Duretz Thibault , de Borst René , Räss Ludovic
Published: March 2020

Reliable numerical models of lithospheric deformation require robust solution methods. The latter should account for a complex and realistic rheological model and should also provide convergent and reproducible results.

Here we present models of crustal-scale deformation that accurately capture the phenomenon of strain localisation in two-dimensions. The use of viscous regularisation yields convergent numerical results. We will compare linearisation methods (consistent tangent, effective viscosity) and discuss the implementation of rheological models (power-law viscous, hardening/softening laws). We will also present three-dimensional models of crustal-scale strain localisation that benefit from both the above-described methods and the computing power of graphical processing units (GPUs).
Multivariate Bias Correction of Climate Simulations: an Intercomparison Study
Authors: François Bastien , Vrac Mathieu , Cannon Alex , Robin Yoann , Allard Denis
Published: March 2020

Climate models are the major tools to estimate climate variables evolutions in the future. However, climate simulations often present statistical biases and have to be corrected against observations before being used in impact assessments. Several bias correction (BC) methods have therefore been developed in the literature over the last two decades, in order to adjust simulations according to historical records and obtain climate projections with appropriate statistical attributes. Most of the existing and popular BC methods are univariate, i.e., correcting one physical variable and one location at a time, and thus can fail to reconstruct inter-variable, spatial or temporal dependencies of the observations. These remaining biases in the correction can then affect the subsequent analyses. This has led to further research on multivariate aspects for statistical postprocessing BC methods. Recently, some multivariate bias correction (MBC) methods have been proposed, with different approaches to restore multidimensional dependencies. However, these methods are not well apprehended yet by researchers and practitioners due to differences in their applicability and assumptions, therefore leading potentially to different results. This study is intended to intercompare four existing MBCs to provide end-users with aid in choosing such methods for their applications. For evaluation and illustration purposes, these methods are applied to correct simulation outputs from one climate model through a cross-validation methodology, which allows for the assessment of inter-variable, spatial and temporal criteria. Then, a second methodology is performed for assessing the ability of the MBC methods to account for the multi-dimensional evolutions of the climate model. Additionally, two reference datasets are used to assess the influence of their spatial resolution on (M)BC results. Most of the methods reasonably correct inter-variable and inter-site correlations. However, none of them adjust correctly the temporal structure as they generate bias corrected data with usually weak temporal dependencies compared to observations. Major differences are found concerning the applicability and stability of the methods in high-dimensional contexts, and in their capability to reproduce the multi-dimensional changes of the model. Based on those conclusions, perspectives for MBC developments are suggested, such as methods to adjust not only multivariate correlations but also temporal structures and allowing to account for multi-dimensional evolutions of the model in the correction.
Degenerate induced magnetospheres
Authors: Barabash Stas , Voshchepynets Andrii , Holmström Mats , Yoshifumi Futaana , Ramstad Robin
Published: March 2020

Induced magnetospheres of non-magnetized atmospheric bodies like Mars and Venus are formed by magnetic fields of ionospheric currents induced by the convective electric field E = - V x B/c of the solar wind. The induced magnetic fields create a magnetic barrier which forms a void of the solar wind plasma, an induced magnetosphere. But what happens when the interplanetary magnetic field is mostly radial and the convective field E ≈ 0? Do a magnetic barrier and solar wind void form? If yes, how such a degenerate induced magnetosphere work? The question is directly related to the problem of the atmospheric escape due to the interaction with the solar and stellar winds. The radial interplanetary magnetic field in the inner solar system is typical for the ancient Sun conditions and exoplanets on near-star orbits. Also, the radial interplanetary field may provide stronger coupling of the near-planet environment with the solar/stellar winds and thus effectively channels the solar/stellar wind energy to the ionospheric ions. We review the current works on the subject, show examples of degenerate induced magnetospheres of Mars and Venus from Mars Express, Venus Express, and MAVEN measurements and hybrid simulations, discuss physics of degenerate induced magnetospheres, and impact of such configurations on the escape processes.
Morphological and chemical characterization of asbestos fibers in solid rocks: Towards an in-situ and combined analytical approach
Authors: Lahondère Didier , Wille Guillaume , Schmidt Ute , Silvent Jérémie , Duron Jéromine , Duée Cédric
Published: March 2020

Asbestos is a commercial term which refers to six minerals that crystallize as fibrous bundles made of very thin and easily separable fibrils. Asbestos fibers have been exploited for a long time and voluntary added in a very large set of manufactured products. In France, asbestos is prohibited since an official decree published in 1997 that prohibits the manufacture, processing, sale and import of asbestos. The asbestos ban has been the subject of an European directive published in 1999. 
Following this ban, a standard was defined in order to specify the sampling, preparation and identification methods for asbestos fibers in samples of commercial origin (ISO 22262-1). For natural materials, no specific analytical protocol is currently defined in France. Searching for asbestos in a rock sample, the commonly used protocols require the reduction of the sample, the grinding of a sub-sample (1 to 2 g) and its calcination in order to eliminate organic matter, then an acid attack to dissolve some constituents (calcite, gypsum). The final test portion (~ 20 mg) is mixed in water, stirred using ultrasound, filtered through a metallized membrane and covered with a new layer of carbon before it can be examined using a transmission electron microscope.
The protocols currently used are long and complex and require the grinding of the sub-sample. This grinding operation is a critical step because it can lead, starting from non-asbestiform minerals, to the artificial formation of more or less fine and elongated fibriform particles (cleavage fragments), quite similar in some cases to asbestos fibers. Grinding is therefore an operation liable to affect the quality of the final diagnosis.
The new protocol presented here was built with the aim of developing an analytical approach specific to coherent rock samples. This protocol does not involve the grinding of the sample and allows the in-situ morphological and chemical characterization of fibrous minerals. It is based on the use of combined analytical techniques (MOLP, EPMA, FESEM-EDS, FIB-SEM, and confocal RAMAN in SEM) from a single support corresponding to a polished thin section. This protocol allows to observe the natural morphologies of the fibers, to measure their dimensions, to characterize the relationships between fibers and the other mineralogical constituents while preserving the texture of the rock and to acquire precise chemical analyzes of the fibers. It also overcomes problems related to the grinding of the sample and the formation of cleavage fragments. This protocol has been tested through the study of several types of massive rock samples. It provides a representative and reliable in-situ diagnosis of the initial state of the fibers in solid rocks.
Towards operational monitoring of ship emissions using Long Path Differential Optical Absorption Spectroscopy
Authors: Schmitt Stefan , Pöhler Denis , Weigelt Andreas , Wittrock Folkard , Seyler André , Krause Kai , Kattner Lisa , Mathieu-Üffing Barbara , Lampel Johannes , Platt Ulrich
Published: March 2020

In contrast to land-based sources of air pollution, which have been regulated and reduced since several decades, NOx and SOx emissions from ships were only recently identified as significant sources of air pollution. As one consequence the sulphur content of ship fuel used within the so-called Sulphur Emission Control Areas (SECA) was recently regulated to a maximum of 0.1% (m/m) (MARPOL Annex VI). Therefore, especially monitoring the emission of sulphur compounds is of particular interest.

Within a 6-week measurement campaign in July and August of 2016, ship emissions were measured at the river Elbe in Germany, near Hamburg using the Long Path (LP)-DOAS technique. The measurements were carried out within the framework of the project MeSMarT (MEasurements of Shipping emissions in the MARine Troposphere), which investigates the influence of ship emissions on chemical processes in the atmosphere. Currently, monitoring of ship emission plumes is typically achieved by a combination of in situ trace gas monitors and meteorological sensors. In contrast to that the LP-DOAS technique is capable of simultaneously measuring signatures of multiple trace gases along an absorption path across a well-frequented waterway close to the ship exhaust-pipes and thus directly in the emission plume at a time resolution of a few seconds.

For our study, a LP-DOAS instrument was set up side by side to an in situ MeSMarT measurement station at the river Elbe at Wedel (15 km downriver of Hamburg harbour) where NO2 and SO2 emission signatures of a total of 5037 ship passes (of 1044 individual ships) were monitored. While the in situ method detected 16% of the ships, the LP-DOAS was able to assign emission plumes to 41% of all passing ships. With meteorology mainly limiting the in situ detection yield, the major limitation for the LP-DOAS was found to be due to the high traffic density and thus the difficulty to unambiguously assign recorded plumes to particular vessels, rather than to the sensitivity to the emission plume itself.

Based on the results of this feasibility study, we present a newly designed LP-DOAS system fulfilling the requirements for operational ship emission monitoring (robust mechanical setup, broad-band long-lifetime light source, compact sealed housing, automized alignment and data acquisition). This new system is now operated continuously to measure the ship emissions on the river Elbe.
No polarity switch? Continental subduction of European crust below the Eastern Alps imaged by receiver functions
Authors: Mroczek Stefan , Tilmann Frederik , Yuan Xiaohui , Pleuger Jan , Heit Ben
Published: March 2020

In the Eastern Alps, teleseismic tomography suggests that there is a switch from European subduction in the west to Adriatic subduction in the east. The dense SWATH-D seismic network is located in the central-eastern Alps between around 10°E and 14.5°E where a change in the dip direction was suggested to occur (e.g. Lippitsch et al. 2003; Mitterbauer et al. 2011). The receiver function method is particularly sensitive to velocity contrasts and so is suited to imaging the interfaces associated with subduction. New receiver function migrations from SWATH-D stations (supplemented by the AlpArray Seismic Network and the EASI profile) show no evidence for Adriatic subduction in the Eastern Alps. Instead, a southward dipping interface [or pair of interfaces with opposite polarity] which we interpreted as subducting  European lower crust can be traced below the Eastern Alps to a minimum depth of 120 km along the extent of SWATH-D. This suggests that in the Alps the polarity flip in subduction does not occur or is located east of our study region beyond 14.25°E, much further east than tomography suggests.
Alternatives to Glyphosate in conservation agriculture: effects on carbon sequestration in a field experiment in northern Italy
Authors: perego alessia , acutis marco , schillaci calogero
Published: March 2020

Conservative Agriculture (CA) practices are recognized to enhance soil organic carbon stock and in turn to mitigate the effect of climate change. One of the CA principles is to integrate cover crops (CC) into the cropping systems. The termination of CC before the cash crop sowing and the weeds control are the most critical aspects to manage in the CA. The technique currently adopted by farmers for the termination of CC implies the use of Glyphosate. However, the European Commission is currently discussing the possibility of banning the use of this herbicide due to the negative effects on human health and the agro-environment. The disk harrow (DH) or the roller-crimper (RC) can be adopted in CA as an alternative to the use of Glyphosate for the devitalization of CC, their incorporation into the soil (in the case of the disk harrow), and the reduction of weed pressure on the subsequent cash crop.

From November 2017 to October 2019, soil organic carbon (SOC, g kg-1) and crop biomass production were observed in a 2-year field experiment located in Lodi (northern Italy), in which minimum tillage (MT) has been applied for the last 5 years. The soil was loamy and SOC was 16.2 g kg-1 at the beginning of the experiment. The winter CC was barley (from November to May) and the cash crop was soybean (from June to October). The experiment consisted in three treatments replied for two consecutive years in a randomized block design: Glyphosate spray + DH + sowing + hoeing (MT-GLY); DH + sowing + hoeing (MT-ORG); RC + sod seeding (NT-ORG).

At the end of 2019, SOC resulted in a higher increase in MT-GLY (+15%) and in MT-ORG (+14%) than in NT-ORG (+6%; p<0.01). This was due to the fact that CC litter in NT-ORG was not in direct contact with soil particles and the process of immobilization was lower than in the other treatments.

Moreover, the increase in SOC resulted positively correlated to the CC biomass (2018+2019), which was significantly lower in NT-ORG. In particular, no differences of soybean and CC between the three treatments were observed at the end of 2018, but MT-GLY resulted in significantly higher CC and soybean biomass at the end of the second year (+32%, p<0.01). MT-GLY allows to stock more carbon via photosynthesis that in turn results in higher SOC content.

However, if we consider the tractor fuel consumption (for Glyphosate spray, DH, RC, hoeing), along with the biomass production, the carbon sequestration did not vary between the three treatments.

Further studies are needed for the definition of optimized field management practices to reduce the passage of machinery while increasing crop production and SOC.
The application of ATLID techniques for aerosol/cloud retrievals to ALADIN
Authors: Donovan David , van Zadelhoff Gert-Jan , Flament Thomas , Trapon Dimitri , Baars Holgar
Published: March 2020

After much anticipation and several years of delay the ALADIN lidar was launched on the Aeolus platform in August 2018. ALADIN is the world’s first space-based Doppler lidar. It operates at 355nm and its main products are line-of-sight winds. Wind-profiles are derived from the Doppler shift of the backscattered signals. Using a variation of the High Spectral Resolution Lidar technique (HSRL), two detection channels are used, a `Mie ‘-channel and a `Rayleigh’-channel. Cloud/aerosol information is also present in the signals, however, ALADIN’s design is optimized for wind observations and the retrieval of aerosol/cloud products is secondary (but important for various applications, e.g. the monitoring of atmospheric composition).

While cloud and aerosol products are secondary products for ALADIN, they are primary products for the EarthCARE lidar ATLID. EarthCARE stands for the Earth Clouds Aerosol and Radiation Explorer and is a joint ESA-JAXA multi-instrument cloud-aerosol-precipitation primarily process study oriented mission planned to be launched in 2022 EarthCARE will embark a lidar called ATLID. ATLID, like ALADIN is a 355 nm HSRL system, but is optimized for cloud/aerosol measurements. Compared to ALADIN, ATLID has a higher spatial resolution, measures the depolarization of the return signal and has a much cleaner Rayleigh- Mie backscatter signal separation. Like ALADIN though, the SNR makes accurate retrievals a challenge. Over the past several years, a suite of cloud/aerosol algorithms have been developed for ATLID that have focused on the challenge of making accurate retrievals of cloud and aerosol extinction and backscatter specifically addressing the low SNR nature of the lidar signals and the need for intelligent binning/averaging of the data. These ATLID approaches have reached a certain stage of maturity; however, they have been tested using mainly simulated data with the aid of the ECSIM multi-instrument end-to-end simulator.

The lessons learned by the application of ATLID-like algorithms on ALADIN data would lead to better ATLID products when it is launched. Further, preliminary work indicates that AT LID-inspired techniques can be successfully adapted to ALADIN measurements and have the potential to lead to improvements in the ALADIN extinction and backscatter products. In this presentation, ATLID-like approaches for ALADIN feature detection and extinction and lidar-ratio retrieval (based on an optimal-estimation approach) will be described. Examples will be presented and compared with observations made using ground-based lidars.
Early Cretaceous extension of Africa and South America: cause and consequences of the Late Aptian intraplate deformation
Authors: Dietrich Pierre , Guillocheau François , Robin Cécile , Roche Vincent , Leroy Sylvie , Rosselo Eduardo , Révillon Sidonie
Published: March 2020

The Jurassic-Cretaceous boundary corresponds to a major step in the Gondwana dispersal. The deformation regime indeed changed from localized, along the incipient ocean (Atlantic Tethys, Somali-Mozambique Ocean), to a highly distributed deformation along several rifts spanning from India to southern South America through Africa including Arabia. The last step of extension is marked by a major unconformity of Late Aptian in age known, since the pioneering work of Edward Suess at the end of the nineteenth century, as the Austrian Unconformity that corresponds to a world-scale plate kinematic reorganization.

We compiled a new map of the Early Cretaceous (Berriasian-Aptian) rifts in Africa and austral South America with a particular emphasis on southern Africa and the Falkland-Malvinas plateau:

At middle wavelength (few tens of kilometers) deformation scale, this Late Aptian event may have stopped the rift regime, corresponding to the transition to a sag setting (Chad and Sudanese rifts), and/or reactivated basement structures (e.g. neoproterozoic faults in the Illizi and Ghadames basins in southern Algeria and Libya). In the central segment of the future South Atlantic Ocean, Late Aptian corresponds to the end of the hyperextension period and the onset of the passive margin coeval with salt deposition.

At a longer wavelength of deformation (several hundreds to thousand of kilometers), the highlighted deformation regime may have changed regional subsidence pattern with for example the overall subsidence of northern Africa and the onset of large marine floodings (e.g. deposition of Nubian sandstones).The Late Aptian unconformity therefore records a major change in the stress within the African plate likely related, considering the scale of deformation, to a reorganization in mantle convection processes.
Compound Specific Stable Sulfur Isotope Analysis (δ34S and δ33S) of Organic Compounds Using Gas Chromatography Hyphenated with Multiple Collector Inductively Coupled Plasma Mass Spectrometry (GC-MC-ICPMS)
Authors: Steffen Kümmel , Faina Gelman , Axel Horst , Harald Strauß , Matthias Gehre
Published: March 2020

Stable sulfur isotope analysis is potentially applicable in various fields in forensics and environmental analytics to investigate the sources and degradation of organic compounds, many of them being priority pollutants in groundwater and the atmosphere. A broader use of sulfur isotopes of organic compounds in environmental studies is still hampered by the availability of precise and easy-to-use techniques. Here we present a method for the determination of stable sulfur isotope ratios using gas chromatography coupled with multiple-collector inductively coupled plasma mass spectrometry (GC-MC-ICPMS) which can be used for both δ34S and δ33S analysis. The method was evaluated using the reference materials IAEA-S-1, IAEA-S-2 and IAEA-S-3 which were converted offline to SF6 prior to analysis. Standardization was carried out by using a two-point calibration approach. The δ34S values obtained by our method are in good agreement (within analytical uncertainty) with the results obtained by the conventional dual inlet method. Additionally, the impact of the used mass resolution (low and medium), the influence of auto-protonation of sulfur isotopes and the effect of isobaric interferences of O2+ on the obtained isotopic ratios was investigated. The analytical precision (1σ) for δ34S and δ33S values was usually better than ±0.1 ‰ for analytes containing >0.1 nmol S. Thus, the presented compound-specific online method should be sufficiently precise to address a wide variety of research questions involving mass independent isotope effects of sulfur-containing organic compounds to discriminate sources or biological and chemical reactions in the environment.
The spreading of suspended matter formed during construction works of offshore wind farms
Authors: Przyborska Anna , Muzyka Maciej , Andrzejewski Jan , Jakacki Jaromir , Rak Daniel
Published: March 2020

Offshore Wind Farms play a significant role in ensuring Europe's energy security. In Poland, a significant increase in the  number  of  newly-constructed  wind turbines  has  been  observed  in  recent  years. Wind power is "clean", but not completely free of environmental impacts. Their impact on the environment is difficult to assess. The impact of dredging works on suspended matter created during construction works will be presented  based on numerical model results. A model has been built based on MIKE, tools supplied by the Danish Hydraulic Institute (DHI) and the Weather Research and Forecasting model (WRF)- mesoscale numerical weather prediction system. Based on the numerical model created, analysis of the temporal and spatial variability of the spreading suspension generated from dredging works carried out during construction works aimed at positioning the wind turbines in appropriate places.

The advective-diffusive character of transported matter is the most natural clean, their direction, turbulent viscosity and sedimentation rate. Authors evaluated that during the construction phase, concentration of the suspended sediment will exceed 10 mg/l, which is denerous value for cod larvae, for short time (no longer than 48 hours) and will cover small area. The deposition will be irrelevant, the largest rate will occur in the immediate vicinity of the construction works and it will decrease with the distance. The range of the transferable suspension will not exceed 15 km. Cumulative factors significantly increase the concentration of the suspension (in a critical case they may even double it). They may occur when simultaneous actions are taken to prepare the foundation for more than one wind turbine at the same time, which is rather technical impossible because there is not a lot of special purpose sea vessel that are able to work on construction of basements of the offshore wind generators.

 
The effect of a strongly stratified layer in the upper part of Mercury’s core on its magnetic field
Authors: Kolhey Patrick , Heyner Daniel , Wicht Johannes , Glassmeier Karl-Heinz
Published: March 2020

In the 1970’s the flybys of NASA’s Mariner 10 spacecraft confirmed the existence of an internally generated magnetic field at Mercury. The measurements taken during its flybys already revealed, that Mercury‘s magnetic field is unique along other planetary magnetic fields, since the magnetic dipole moment of ~190 nT ∙ RM3 is very weak, e.g. compared to Earth’s magnetic dipole moment. The following MESSENGER mission from NASA investigated Mercury and its magnetic field more precisely and exposed additional interesting properties about the planet’s magnetic field. The tilt of its dipole component is less than 1°, which indicates a strong alignment of the field along the planet’s rotation axis. Additionally the measurement showed that the magnetic field equator is shifted roughly 0.2 ∙ RM towards north compared to Mercury‘s actual geographic equator.

Since its discovery Mercury‘s magnetic field has puzzled the community and modelling the dynamo process inside the planet’s interior is still a challenging task. Adapting the typical control parameters and the geometry in the models of the geodynamo for Mercury does not lead to the observed field morphology and strength. Therefore new non-Earth-like models were developed over the past decades trying to match Mercury’s peculiar magnetic field. One promising model suggests a stably stratified layer on the upper part of Mercury’s core. Such a layer divides the fluid core in a convecting part and a non-convecting part, where the magnetic field generation is mainly inhibited. As a consequence the magnetic field inside the outer core is damped very efficiently passing through the stably stratified layer by a so-called skin effect. Additionally, the non-axisymmetric parts of the magnetic field are vanishing, too, such that a dipole dominated magnetic is left at the planet’s surface.

In this study we present new direct numerical simulations of the magnetohydrodynamical dynamo problem which include a stably stratified layer on top of the outer core. We explore a wide parameter range, varying mainly the Rayleigh and Ekman number in the model under the aspect of a strong stratification of the stable layer. We show which conditions are necessary to produce a Mercury-like magnetic field and give a inside about the planets interior structure.
Correlation of air temperature and land surface temperature of Landsat-8 in cities of South Korea
Authors: Choi Sungwon , Jin Donghyun , Seong Noh-hun , Jung Daeseong , Han Kyung-soo
Published: March 2020

Recently, there are many problems in urban area such as urban thermal island phenomenon, changes in urban green area, changes in urban weather and various urban types. And surface temperature data have been utilized in many areas to identify these phenomena. This means that surface temperatures is an important position in urban greenery and weather. High temporal and spatial resolution satellite data are needed to continuously observe the phenomenon in urban areas. In addition, the surface temperature varies from type of indicator, topography, and various factors, so there is a limit to the in-situ data for observing changes throughout the city. Therefore, various organizations around the world are currently conducting surface temperature measurements using satellites. However, the use of data in clear pixel is essential for accurate surface temperature calculations using satellites, but the accuracy of results will be reduced if the data from in the pixel which conclude clouds.

Therefore, we tried to solve these problems by analyzing the correlation between the air temperature data and the Landsat-8 LST data. The variables used in the correlation analysis are air temperature, Landsat-8 LST, NDVI and NDWI, and the study period is 2014 to 2016 and the study area is South Korea's five cities (Seoul, Busan, Daejeon, Daegu, Gwangju). For correlation analysis, the air temperature data points provided by the Korea Meteorological Administration and the Landsat-8 pixels were matched, and the correlation coefficient calculated by the correlation analysis was applied to the Landsat-8 satellite to calculate the LST. We validated by direct comparison the re-produced Landsat-8 LST with observed Landsat-8 LST. And the result of validation showed a high correlation of 0.9. It shows that compensation for the satellite's shortcomings from clouds by using the correlation between temperature and LST.
Soil Carbon Dioxide Emission in Extreme Environment of the Center of Moscow Megapolis
Authors: Dolgikh Andrey , Petrov Dmitriy , Brianskaia Inna , Demina Soryia , Mahinya Ksenia , Romzaikina Olga , Dobrianskii Aleksandr
Published: March 2020

Moscow is the largest megapolis in Europe. The area of sealed areas in the center of Moscow is more than 50% (without hydrological objects). Anti-icing mixtures, car traffic, aerosols, dust, trampling - all this leads to the maximum stress of ecosystems in an urban environment Soil emission is the largest component of Gross Respiration in terrestrial ecosystems, including cities. Field measurements of emission allow estimating and comparing the state of both the underground tier and the entire ecosystem in different functional zones of a city with different types of vegetation. Soil emission is the easiest to measure, as compared to other fluxes of С-exchange. In 2019, field measurements of carbon dioxide emissions were carried out at 15 key sites (15 times, 1 per 2 weeks), which showed that in the historic center, not only the temperature at different depths of the soil, soil moisture, carbon content, particle size distribution, but also the diversity of factors combined into a group of "land use", namely: human tillage, irrigation, lawn mowing, garbage removal, sprinkling peat-compost mixture, trampling, bringing anti-icing reagents, etc., have a contrasting effect on carbon dioxide emissions from urban soils. In some cases, the emission is below the conditional background values (urban forest), in other cases, it is higher up to several times, which allows a new assessment of soils of unsealed (open) areas of the center of a megapolis as an important component of the (micro-) regional C-cycle. The data obtained allow comparing the current state of the upper part of the underground tier of urban ecosystems under the maximum anthropogenic load in the territory of a modern large city, where the share of open surfaces is minimal. The territories, where the ground layer is represented by cultivated lawn, are characterized by the maximum values of soil carbon dioxide emission.

The study was supported by the Russian Research Foundation #19-77-30012 (field measurements in the periphery of Moscow) and the Russian Foundation for Basic Research #18-35-20052 (field measurements in the historic center of Moscow).