bluuebunny/crossref_metadata_2025 huggingface dataset:
Future trends of precipitation extremes in the eastern Mediterranean
Authors: Zittis George , Bruggeman Adriana , Hadjinicolaou Panos , Lelieveld Jos
Published: March 2020

The broader region of the eastern Mediterranean is a well-known climate change hot-spot. The combined warming and drying of the region’s mean climatic conditions have already been identified by a number of observation and modeled-based studies. Nevertheless, the future evolution of rainfall extremes has not been extensively assessed. Such events can cause severe flooding, damages to infrastructure and human casualties. In the present contribution, we use the output of a regional climate simulation in order to explore changes in the magnitude of such events. The WRF limited area model is used to dynamically downscale the bias-adjusted output of the global CESM1 model in a horizontal resolution of 12-km for the 1981-2100 period. In terms of greenhouse gas emissions and concentrations, a “business-as-usual” scenario (RCP8.5) was considered. Trends of the annual values of maximum daily rainfall are explored by using the non-parametric Sen’s Slope Estimator while the significance of these trends is assessed by applying the Mann-Kendall trend test. Preliminary analysis indicates negative trends for most of the region, with the exception of northern Turkey and parts of the Balkans. Despite these negative trends, the absolute magnitude of the most extreme events is projected to increase in the majority of the grid cells. Results are compared with gridded observations and model output from the EURO-CORDEX database.    
Exploring the effect of varying soil organic matter contents on current and future moisture supply capacities of six Italian soils
Authors: Bonfante Antonello , Basile Angelo , Bouma Johan
Published: March 2020

The Available Soil Water Capacity (AWC) is standard data in most soil databases and expresses soil water contents in the rootzone between field capacity (FC;-33 kPa) and permanent wilting point (WP; -1500 kPa). Literature suggests that increasing the content of soil organic matter (SOM) of a given soil does not significantly increase AWC and this has important implications when estimating soil moisture supply to crops and evaluating the potential for climate mitigation. For most crops, the real FC values vary between -10 and -50 kPa in different soils and WP values between -800 and -1500 kPa. Thus standard values for AWC of FC and WP do not represent field conditions in many soils. When exploring AWC for six Italian soil series, ranging from clay to sandy, AWC values at increasing %SOM were lower in clay soils and higher in sand as compared with actual conditions, which could be explained by considering the shape of the corresponding moisture retention curves. Rather than focus on static AWC values to define moisture supply to plants, real or actual soil moisture supply capacities (MSC) can be obtained by dynamic modeling of the soil-water-atmosphere-plant system, including a “sink-term” indicating a continuous relation between water uptake and negative pressure head of soil water and evaporative demand. Also, only models allow exploration of the effects of future severe IPCC climate scenario RCP 8.5. Thus, studying MSC for the six Italian soil series showed that MSC values were: (i) on average 30% higher than the corresponding AWC; (ii) distinctly different for the six soils; (iii) affected by declines of 1-9% as a result of the effects of future climate scenarios.; (iv) not significantly affected by increases of %SOM when considering climate change, except for the sand. Generalizations as to the effect of future climate scenarios and %SOM on MSC can only be realistic when modeling is performed for soil series in different climate zones. The contribution has been published in Geoderma journal by Bonfante A., Basile A., and Bouma J. (https://doi.org/10.1016/j.geoderma.2019.114079).
Estimating in-situ soil moisture dynamics from soil thermal dependencies
Authors: Hoffmeister Svenja , Haßler Sibylle , Mälicke Mirko , Zehe Erwin
Published: March 2020

Soil moisture plays an important role for the understanding of hydrological processes due to its influence on water and energy fluxes between the soil surface and the atmosphere. Knowledge of soil water dynamics is especially critical in water-scarce areas. In agroforestry systems, for instance, excessive competition for water between the trees and crops might outweigh the benefits of the system, thus preventing a successful implementation.
Several techniques exist for measuring soil moisture and commercial devices vary widely in cost, reliability and efficiency. An alternative approach could be to estimate soil moisture dynamics from soil thermal dependencies. Similar approaches are already being used in remote sensing, as soil moisture influences the soil thermal properties and thus the surface energy balance and soil heat transfer. However, few studies have tested the feasibility of estimating in-situ soil moisture dynamics from soil temperature dynamics within a soil profile. Temperature sensors are cheaper, smaller and technically robust and could thus provide an interesting alternative to available commercial soil moisture sensors.
In this study, we quantify the effect of soil moisture on phase shift and amplitude attenuation of soil temperature to estimate soil moisture content. We investigate these relationships from two different angles. Firstly, we use virtual measurements in coupled model simulations of soil water and soil heat dynamics to infer the general feasibility and precision of the method in an idealized error-free world. A sensitivity analysis can give insights on how the parametrization of the thermal diffusivity affects the precision and feasibility. Secondly, we compare findings from these simulations to results from analyzing time series of both soil moisture and soil temperature measured in an agroforestry field site in South Africa. A tentative analysis of these time series reveals that the amplitude attenuation and phase shift in the daily temperature signal is clearly sensitivity to changes in soil moisture. Finally, we aim to setup a coupled model for the study site based on the available soil hydraulic and textural data and compare simulated with observed phase shifts and attenuations at different depths.
Non-reasonable but efficient use of schemes in current model to improve realistic explicit convection modelling
Authors: messager christophe , honnorat marc
Published: March 2020

There is actually no limitation of current high-resolution weather model for producing simulation and forecast of convection at kilometer and infra-kilometer horizontal resolutions. However, the disappointing results as well as the associated huge amount of computer resources required may lead to focus on Large Eddy Simulation model instead. However, the use of LES is not trivial and required a long and non-portable adjustment over the region of interest. Also, it is difficult to use in operational mode for daily forecast since they require specific inputs.

In the other side, pushing the current regional or Limited Area Model towards very high resolution is a convenient way to reach explicit resolution of convective process for instance. However, an explicit simulation is not a guarantee of a realistic result mainly due to the fact that initial condition is crucial as well as all other descriptions of the environment (soil, vegetation, sst, etc) and use of correct parameterization schemes.

For instance, within the WRF model framework, one can identify more than 4000 set of parameterizations plus all the scheme adjustments and threshold associated to.

However, a physically based analyze of what it is necessary for a realistic and explicit convection simulation may conduct a physicist user to define its “ideal” physics with what it already exists in the model. It may conduct to so-called unrealistic model requests in term of computation requirement regarding the radiative, the turbulence and the microphysics schemes but it does works with HPC systems. This kind of parameterization will be presented here and used with a very realistic vertical circulation into convective systems with convective updraft and downdraft modelling, from few meters up to several kilometers height.
Development of an Indoor Positioning and Navigation System using Wi-Fi network and BLE beacons for the Smart Campus: A case study
Authors: Trybała Paweł
Published: March 2020

Nowadays, powerful hand-held devices, like smartphones, tablets and smartwatches, are ordinary things, which many people take anywhere they go. One of the major advantages of this technology is the ability to locate its user by means of GNSS or cellular positioning. Paired with popular, free mobile mapping applications, it greatly simplifies the problem of finding oneself in the unknown place, calculating the best route to one’s destination by various means of transport or tracking one’s movement. For this reason, outdoor navigation is a well-established and widespread technology. The problem arises, when positioning and wayfinding are needed in a GNSS-denied environment, e.g. a building or a mine. In a complex, large or multi-floor constructions modern techniques for easing the navigation through them are rarely applied. Recent years brought numerous new, promising approaches and algorithms for solving a problem of indoor positioning and navigation, but many of them can’t be easily implemented on a typical smartphone or conveniently used. This includes Simultaneous Localization and Mapping (SLAM) and algorithms based on Augmented Reality (AR). It seems that the most feasible and cost-efficient methods are those based on Wi-Fi Access Point (AP), low-cost Bluetooth Low Energy (BLE) or Ultra-Wideband (UWB) beacons. This research aims to describe the process of developing such an Indoor Positioning and Navigation System in one of the buildings, located on the campus of the Wroclaw University of Science and Technology, and identify the main challenges that have to be overcome during this process. Feasibility of available GIS software solutions for this application is analyzed. Directions for future research and development are discussed.
What can we learn from TROPOMI observations of biomass burning NO2?
Authors: Richter Andreas , Lange Kezia , Latsch Miriam , Burrows John P.
Published: March 2020

Most of the anthropogenic emissions of nitrogen oxides (NOx = NO2 + NO) are linked to burning of fossil fuels for energy production, transportation or industrial processes. However, biomass burning and in particular large wild fires in tropical and sub-tropical regions can also be important sources of nitrogen oxides, at least locally. Depending on the size of the fires, particles and gases are lifted into the free troposphere and even higher, increasing the atmospheric lifetime of NOx in these plumes and enabling long range transport.

The TROPOMI instrument on board of Sentinel 5 precursor (S5p) is a nadir viewing UV/vis imaging spectrometer launched in October 2017 and operationally providing data since July 2018. One of the main products that can be retrieved from TROPOMI spectra is tropospheric and total column NO2. Compared to previous UV/vis satellite instruments such as GOME, SCIAMACHY, GOME2 and OMI, TROPOMI has a higher spatial resolution of 3.5 x 5.5 km2. This reduced foot print size enables detection and evaluation of more localised sources such as individual fires and their plumes, and better separation of different contributions to the overall NO2 loading.

In this presentation, IUP-Bremen TROPOMI NO2 retrievals are evaluated for biomass burning signatures during 2018 and 2019, two years with very different burning seasons. The amounts and spatial distributions of NO2 from fires are compared between the two years and between different fire regions, and their impact on regions downwind of the sources is investigated.
Decadal variability of nutrients and biomass in the southern region of Kuroshio Extension
Authors: Ma Jinfeng , Lin Pengfei , Chai Fei , Xiu Peng , Liu Hailong
Published: March 2020

The phytoplankton and zooplankton biomass as well as nutrients in the southern region of Kuroshio Extension (KE) presents obvious decadal variability. Both local and remote links between biomass and physical properties are investigated by comparing satellite observations and the outputs from a biological-physical coupled model. The Regional Ocean Model System (ROMS) and Carbon, Silicate, and Nitrogen Ecosystem (CoSiNE) cover the entire Pacific Ocean. The ROMS-CoSiNE model captures the spatial distribution and decadal variation of the key biological variables including phytoplankton and zooplankton biomass and nutrients in the upper ocean around the KE. The decadal variation in the region is mainly caused by the westward-propagating signals that originate from the central and eastern North Pacific. Specifically, these signals are induced by the decadal oscillation of vertical displacement related to large-scale decadal Pacific modes, such as the North Pacific Gyre Oscillation (NGPO).The evidence obtained here includes not only from surface variables (sea surface height and surface chlorophyll) but also from the variables in the deeper ocean (thermocline, subsurface nutrients, upper 100-m phytoplankton and zooplankton biomass) in the KE region. The signals of the variables in the southern KE region significantly lag that of the NPGO in the central and eastern North Pacific by about 2-4 years. The mixed layer nitrogen budget is conducted to evaluate the contribution of vertical and horizontal advection for the decadal variation of nutrients. 
Automatic extraction of modern reefs satellite images geometries using Computer Vision
Authors: Jimenez Soto Grisel , Arshad Beg Mirza , Poppelreiter Michael C. , Rahmatsyah Khaidi
Published: March 2020

Three selective, global – scale areas for modern’s reef sites have been selected on exploring the automatic metrics extraction for further studies among the relationships between reef morphology and the surrounding oceanographic conditions that can potentially be used as an input parameter for training images for Multiple Point Statistics simulations.

Obtain geometric features from satellite images is a very laborious task and hard work when making manually. Nevertheless, automatic geometric features detection is a challenging problem due to the varying lighting, orientation, and background of the target object, especially when analyzing raw images in RGB format. In this work, a robust algorithm programmed in python is presented with the purpose of estimate automatically the geometric properties of a set of coral reef islands located in South East Asia. First, a python code load massive satellite imagery from a specific folder RGB format, then each raw coral reef island image is resized, converted from RGB band to gray, smoothed and binarized using Open Computer Vision Library available in python 3. The island edge information contains very prominent geometric attributes that characterize their behavior, thus morphological transformations were applied to define the contour of the island. Moreover, a structural analysis and shape descriptors were made in a set of images in order to numerically calculate the characteristics of the island.  Finally, a total of 27 satellite images were processed by the algorithm successfully, only two images were not segmented correctly because the illumination and intensity of the predominant colors, especially blue, were different from the rest of the images. This dataset was exported from python to Microsoft Excel spreadsheets and CSV format.
Investigating stratospheric changes between 2009 and 2018 with aircraft, AirCores, a global model and a focus on CFC-11
Authors: Laube Johannes , Ploeger Felix ,   Stratospheric CFC-11 team
Published: March 2020

We present new observations of trace gases in the stratosphere based on a cost-effective sampling technique that can access much higher altitudes than aircraft. The further development of this method now provides detection of species with abundances in the parts per trillion (ppt) range and less. We focus on mixing ratios for CFC-11 and CFC-12 which are important for understanding stratospheric ozone depletion and circulation. After demonstrating the quality of the data through comparisons with ground-based records and aircraft-based observations we combine them with the latter to demonstrate their potential. We first compare them with results from a global model driven by three widely used meteorological reanalyses (ERA-Interim, JRA-55, MERRA-2). Secondly, we focus on CFC-11 as recent evidence has indicated renewed atmospheric emissions of that species relevant on a global scale. Because the stratosphere represents the main sink region for CFC-11, potential changes in stratospheric circulation and troposphere-stratosphere exchange fluxes have been identified as the largest source of uncertainty for the accurate quantification of such emissions. Our observations span over a decade (up until 2018) and therefore cover the period of the slowdown of CFC-11 global mixing ratio decreases measured at the Earth’s surface. The spatial and temporal coverage of the observations is insufficient for a global quantitative analysis, but we do find some trends that are in contrast with expectations; indicating that the stratosphere may have contributed to tropospheric changes. Further investigating the model data we find that the required dynamical changes in the stratosphere required to explain the apparent change in tropospheric CFC-11 emissions after 2013 are possible, but with a very high uncertainty range in the change of stratosphere-to-troposphere flux of CFC-11. This is partly caused by the high variability of mass flux from the stratosphere to the troposphere, especially at time scales of a few years, and partly by large differences between runs driven by different reanalysis products, none of which agree with our observations well enough for such a quantitative analysis.
Evolution of crystallographic preferred orientations in flowing polycrystalline ice: A continuum modelling approach validated against laboratory experiments
Authors: Richards Daniel , Pegler Sam , Piazolo Sandra , Harlen Oliver
Published: March 2020

Understanding the anisotropic flow of ice is likely a key factor for the reliable prediction of the evolution of certain regions of the Earth’s ice sheets. Anisotropy of the crystal lattice alignment of ice grains is typically neglected in the large majority of ice-sheet models, however the viscosity of ice can vary by a factor of at least 9 in different directions, indicating the potential to provide a dominant control. Even though anisotropy can have a large regional influence, its effects are currently poorly understood. For example, it is an open question as to how different varieties of crystal fabrics are produced by different forms of deformation, and how these dynamics vary with temperature.

To address these questions, we use a continuum-mesoscopic approach, proposed by Faria (2006a) and Placidi (2010) to model the evolution of the ice crystallographic preferred orientations (CPOs). The model assumes strain induced crystal lattice rotation i.e. crystal plasticity with rigid body rotation where parameters representing the following processes are incorporated: the relative importance of basal slip, the magnitude of grain-boundary migration and the magnitude of rotation recrystallization. We solve the system using a new spectral method, which is computationally highly efficient, and able to fully resolve the multiple dimensions of the problem (time, space and the two dimensions of orientation angle). By considering the predictions of the model in the cases of deformation representing shear and compression, the model is determined to reproduce all the detail features observed in ice CPOs evolution such as secondary clusters or cone shapes. The results show excellent agreement with experiments of ice deformation in both shear and compression. The experimental comparison is used to determine the first constraints on three temperature-dependent dimensionless numbers defining the relative important of the recrystallization and slip processes. With these dependencies constrained using shear experiments, the application of the model results is able to reproduce the observations of crystal structure in compressive experiments with no further fitting parameters. The model is thus found to provide good agreement with laboratory experiments  across a range of temperatures, strain rates and flow fields.  Moreover, the predicted patterns correspond qualitatively to those observed in natural ice from cores, with our results providing the first theoretical demonstration of the characteristics of the fabric structure. 
Effect of decontamination on sediment discharge from mountain stream to river and cesium transfer in Yamakiya district
Authors: Makino Fumiaki , Onda Yuichi , Taniguchi Keisuke , Slim Mitbaa , Wakiyama Yoshifumi , Kozuka Syohei , Kato Hiroaki , Iwagami Sho
Published: March 2020

After the accident of the Fukushima nuclear power plant, decontamination works had been conducted from 2013 to 2017 in the area of heavly contamination by fallout radionuclides. Although decontamination is conductive to decrease the air dose rate, associated disturbances of soil, such as scraping, reversal tillage, and soil dressing. These decontamination works, in turn, could increase the sediment discharge to downstream, but no studies are available on the effect of the decontamination in upstream headwaters that affects sediment discharge in rivers. Furthermore, decontamination has been carried out in the target area, the Yamakiya area, from 2013, and decontamination has been completed in the spring of 2016, decontamination work has been completed in 2017, and the residents have been returned. The sediment runoff due to human activities can be different from the sediment runoff due to decontamination.

The purpose of this study was to study the relationship between sediment dynamics and Cs dynamics due to decontamination, and the changes in sediment dynamics due to the return of residents. Observations and historical data were analyzed at Iboishi mountain in the forest and the middle stream of Kuchibuto. We have been monitoring suspended sediment Cs-137 concentration, water runoff, and suspended sediment runoff since 2014 at the middle point of the Kuchibuto River and since 2013 at Mt.Iboishi. The slope of the approximation line was compared with the LQ curve for comparison of the amount of sediment runoff. In the middle of the Kuchibuto river, it was 1.54 in 2014, 2.28 in 2015, 2.12 in 2016, 0.164 in 2017, and 0.189 in 2018. At Iboishi mountain in the forest, it was 1.72 in 2014, 0.947 in 2015, 1.39 in 2016, 0.219 in 2017, and 1.15 in 2018. The same tendency was shown in the slopes of the LQ curves in the middle part of the Kuchibuto river and the Iboishi mountain in the forest area. The Cs concentration was high until November 2015, but since then, the Cs concentration has decreased. These results suggest that the increased sediment discharge due to decontamination of the forest area affected the sediment discharge in the middle stream of the Kuchibuto River.
Joint analyses of nitrate transit time distributions and legacy effects in catchments with contrasting physical settings in Germany
Authors: Ehrhardt Sophie , Musolff Andreas , Weber Michael , Ebeling Pia , Kumar Rohini
Published: March 2020

Increased anthropogenic inputs of nitrogen (N) to the biosphere during the last decades have resulted in increased groundwater and surface water concentrations of N (primarily as nitrate), posing a global problem. Although measures have been implemented to reduce N inputs, they have rarely led to decreasing riverine nitrate concentrations and loads. This limited response to the measures can either be caused by the accumulation of organic N in the soils (biogeochemical legacy) –or by long travel times (TTs) of inorganic N to the streams (hydrological legacy). Both legacy types determine the temporal dimension of catchment response on the one hand and the quantitative dimension on the other hand.

Here we analyze several decades of N input, water quality and discharge observations from 62 catchments in 8 federal states in Germany. The selection of catchments represents a wide range of land use, geology and soils, topography and hydroclimate. In an input-output assessment, N input from atmospheric deposition, waste water treatment and agriculture is compared with riverine N concentrations (nitrate-N) as N output. We assess jointly the N budget and the effective TTs of N through the soil and groundwater compartments. In combination with long-term trajectories of the C–Q relationships, we evaluate the potential for and the characteristics of an N legacy.

Our data-driven approach shows a mean legacy of 73 % (spanning 0 – 90 %), cumulating to a total missing mass of 4270 kg N/ha a. Log-normal distributed TTs have a mean of 6 years (0.8 – 34 years) with an R2 of 89 % between the convolved N input and N output. Due to the chemostatic export regime (mean CVC/CVQ: 0.36 < 0.5) and relatively short TTs in most of the catchments, the biogeochemical legacy seems to dominate the catchment responses nowadays. Further analyses aim to investigate the controlling parameters determining the N time lags and legacies type. A correlation analyses hint to topographic parameters, mainly slope and topographic wetness index, as main controls of the legacy i.e. that flat catchments have the tendency to higher legacies or retention.

Legacies of almost ¾ of the N input pose a challenge to the limited denitrification potential of soils and aquifers or indicate a massive N accumulation in the catchment. Latter can cause elevated N concentrations for the next decades explaining at the same time a limited response to measures. The dominant biogeochemical legacy suggests that management needs to address both a longer-term reduction of N inputs and shorter-term mitigation of past high N loads by favoring denitrification.
Earthquakes without aftershocks: Is there a link to fluid-absent geodynamics?
Authors: Gunatilake Thanushika , Miller Stephen A.
Published: March 2020

One question that remains unanswered is why some earthquakes are preceded by foreshocks and generate aftershocks by the thousands, while other similarly-sized (or larger) earthquakes produce few, if any, foreshocks or aftershocks. Current understanding equates large magnitude earthquakes with hundreds or even thousands of aftershocks, however a magnitude 7.1 earthquake in Mexico in 2017 and a magnitude 8.0 earthquake in 2019 in Peru generated no foreshocks and no aftershocks (M>4), while the 2020 M6.4 earthquake in Puerto Rico was preceded by ten foreshocks (M>4) and more than sixty aftershocks (M>4) in the first week. The 2019 Ridgecrest earthquake (M7.1) in California was preceded by a M6.4 foreshock and thousands of aftershocks, and this is relevant because this sequence occurred in the fluid-rich Coso hydrothermal/volcanic region. Other examples include the 2001 Kunlun (Tibet) earthquake (M=7.8) that generated a mere 12 aftershocks (M>4) in the first three weeks, while the tectonically similar 2002 Denali earthquake (M=7.9) spawned nearly 160 aftershocks (M>4) in the first three weeks. We attribute this contrasting behaviour to the geodynamic setting; subduction (and thus devolitization) underlies Denali, while a fluid-absent thickened crust (from the Himalayan orogeny) underlies Tibet.

In this work, we performed a global inventory of large earthquakes and their aftershocks, and find strong evidence that aftershock productivity correlates with the geodynamic and petrological settings hosting the earthquakes. In cases where deep fluid sources are likely (using geodynamic arguments), we find that earthquakes are sometimes preceded by foreshocks, and always produce rich aftershock sequences. On the contrary, using the same geodynamic arguments, we show that regions without an obvious deep fluid source produce few, if any, aftershocks. From this study, we hypothesize that, in general, fluid-absent geodynamic environments generate a dearth of aftershocks, while fluid-rich environments generate aftershock sequences that follow the typical Gutenberg-Richter, Bath and Omori Laws.
Deep Learning based cloud parametrization for the Community Atmosphere Model
Authors: Behrens Gunnar , Eyring Veronika , Gentine Pierre , Pritchard Mike S. , Beucler Tom , Rasp Stephan
Published: March 2020

Despite significant progress in climate modeling over the last decades, the spread in simulated equilibrium climate sensitivity, i.e. the change in global mean surface temperature after a doubling of atmospheric CO2 concentrations, has not decreased since the 1970s. Estimates from the Coupled Model Intercomparison Project Phase 5 (CMIP5) range between 2.1 and 4.7°C, and this range is even larger in CMIP6. A large contribution to this uncertainty stems from differences in the representation of clouds and convection occurring at scales smaller than the resolved model grid resolution. Machine learning approaches have recently been shown to be potentially powerful alternatives to physical parametrizations of convection (Gentine et al. 2018; Rasp et al. 2018). Despite improving understanding of the minimization of generalization errors in out-of-sample climate states (Beucler et al. 2019) these approaches struggle to capture the full variability observed in the training and validation data. First experiments with autoencoder-decoder structures illustrate a compatible skill in comparison to feedforward neural networks.

In this study we modify the existing neural network parametrization using more advanced neural network structures. The new parametrization is tested with the Community Atmosphere Model Version 3 for different climate states. This work is a contribution to the development of complex subgrid-scale convective and turbulence parametrizations performed within the recently awarded European Research Council (ERC) Synergy Grant “Understanding and modelling the Earth system with machine learning (USMILE)”.

 

 

References:

Gentine, P., Pritchard, M.S., Rasp, S., Reinaudi, G., & Yacalis, G. (2018): Could Machine Learning Break the Convection Parameterization Deadlock? Geophysical Research Letters, 45, 5742-5751

Rasp, S., Pritchard, M.S., & Gentine, P. (2018): Deep learning to represent subgrid processes in climate models. Proceedings of the National Academy of Sciences

Beucler, T., Rasp, S., Pritchard, M.S., Gentine, P.,Ott, J. & Baldi, P. (2019): Enforcing Analytic Constraints in Neural-Networks Emulating Physical Systems. Physical Review Letters, https://arxiv.org/abs/1909.00912
The CoNTESTA Project: Impacts of geomagnetic field changes on cosmogenic nuclide production-rate variability and implications for surface-exposure dating
Authors: Jackson Margaret , Bromley Gordon , Blard Pierre-Henri , Hemming Sidney
Published: March 2020

Determining the geographic footprint of past climate events is a fundamental step in identifying the mechanisms that drive and propagate these changes around the globe. Glacial deposits are a particularly robust source of such data; glaciers are sensitive indicators of climate that leave records of their past fluctuations on the landscape. Given precise chronologic control, glacial deposits can be used to reconstruct past climate variability. Recent advances in cosmogenic nuclide surface-exposure dating have established past glacial fluctuations as a key climate proxy. However, uncertainties in the application of cosmogenic nuclide production-rate-scaling frameworks hinder efforts to compare past glacial fluctuations with other records of past climate conditions. Production-rate scaling is particularly uncertain in the tropics, where the theorized impacts of changing magnetic field strength on the incoming cosmic ray flux are greatest. Here we present results in-progress from the CoNTESTA [Cosmogenic Nuclide Temporal and Elevation Scaling: Testing and Application] Project, which seeks to establish multiple nuclide production-rate calibration sites of varying age from the low latitudes in order to assess directly the impacts of changing magnetic field strength on nuclide production over time. We also report new data that address empirically the impacts of elevation on nuclide production. The results of this project will strengthen our understanding of cosmogenic nuclide production globally and will improve surface-exposure age calculations from all regions. This in turn will enable more robust assessment of the global phasing of glacial fluctuations and will forward our understanding of landscape dynamics and Earth surface history. 
Quantitative automated mineralogy to constrain metamorphic processes using ZEISS Mineralogic
Authors: Taylor Rich , Hill Eddy , Lanari Pierre , Clark Chris , Johnson Tim
Published: March 2020

The Scanning Electron Microscope (SEM) is the most prolific piece of analytical equipment in the Earth Sciences, therefore quantitative mineral chemistry obtained directly from the SEM has the potential to streamline many geological fields. Mineral chemistry provides direct constraints on geological processes that are used in a wide variety of Earth Science disciplines. As a result, major element analysis of rock forming minerals have been one of the major contributors to geochemistry for decades. Electron beam techniques have been the most widely used method of obtaining in situ major element chemistry, dominated by the quantitative Wavelength Dispersive Spectroscopy (WDS) employed by the Electron Probe Micro Analyser (EMPA). More rapid, and typically more qualitative Energy Dispersive Spectroscopy (EDS) major element measurements are often obtained on a standard SEM instrument.

The relative simplicity of the EDS technique saw the growth of automated mineralogy systems beginning in the 1980’s. The peaks of EDS spectra are characteristic of the major elements present, and therefore lookup tables can be used to match the spectra to known mineral compositions and provide a likely mineralogy in both grain mounts and mapped thin sections. The automated mineral analysis technique remained essentially unchanged for decades, with an experienced operator required for many of the analytical tasks, such as creating the files for matching spectra to known minerals, processing the data, and interpreting complex phases and solid solutions (e.g. Fe/Mg-bearing silicates).

The ZEISS Mineralogic automated quantitative mineralogy (AQM) takes a new approach, using EDS detectors, but following an analytical protocol more closely aligned with EPMA. A combination of matrix corrections, peak deconvolution, and standard calibration means that peak intensities are converted directly into wt% element directly at the time of analysis. The result is a data output that can be immediately interpreted, even for minerals not previously analysed, by both new and experienced users.

Here we demonstrate the use of the ZEISS Mineralogic system for mapping thin sections from high grade metamorphic rocks. The bulk chemistry of the entire thin section, as well as individual mineral compositions can be used to constrain P-T conditions directly from the SEM, without the need for an additional step of obtaining mineral chemistry from an EPMA. With quantitative analysis at every pixel, major element profiles can be obtained at any point in the thin section, and P-T can therefore be determined from any domain within the mapped section. This approach makes the use of P-T pseudosections possible with greater speed and flexibility than has previously been possible.
Evolution of mechanical properties of lava dome rocks across the Soufrière Hills eruption, and application in discrete element models
Authors: Harnett Claire , Kendrick Jackie , Lamur Anthony , Thomas Mark , Stinton Adam , Wallace Paul , Lavallee Yan
Published: March 2020

Lava dome collapses pose a hazard to surrounding populations, but equally represent important processes for deciphering the eruptive history of a volcano. Models examining lava dome instability rely on accurate physical and mechanical properties of volcanic rocks. Here we focus on determining the physical and mechanical properties of a suite of temporally-constrained rocks from different phases of the 1995–2010 eruption at Soufrière Hills volcano in Montserrat. We determine the uniaxial compressive strength, tensile strength, density, porosity, permeability, and Young’s modulus using laboratory measurements, complemented by Schmidt hammer testing in the field.

By viewing a snapshot of each phase, we find the highest tensile and compressive strengths in the samples attributed to Phase 4, corresponding to a lower permeability and an increasing proportion of isolated porosity. Samples from Phase 5 show lower compressive and tensile strengths, corresponding to the highest permeability and porosity of the tested materials. Overall, this demonstrates a reliance of mechanical properties primarily on porosity, however, a shift toward increasing prevalence of pore connectivity in weaker samples identified by microtextural analysis demonstrates that here pore connectivity also contributes to the strength and Young’s Modulus, as well as controlling permeability. The range in UCS strengths are supported using Schmidt hammer field testing. We determine a narrow range in mineralogy across the sample suite, but identify a correlation between increasing crystallinity and increasing strength. We correlate these changes to residency-time in the growing lava dome during the eruption, where stronger rocks have undergone more crystallization. In addition, subsequent recrystallization of silica polymorphs from the glass phase may further strengthen the material.

We incorporate the variation in physical and mechanical rock properties shown within the Soufrière Hills eruptive into structural stability models of the remaining over-steepened dome on Montserrat, considering also the possible effect of upscaling on the edifice-scale rock properties, and the resultant dome stability.
Ecological protection effects on typical slopes with various combination of engineering measures and plant measures
Authors: yan zhang , tingning zhao
Published: March 2020

In recent years, due to the rapid development of the China, various production and construction projects have produced many exposed slopes which need to be restored by special recovery measures. However, the regulation effects of vegetation on sediment of slopes with different ecological recovery measures are different. Taking the reconstruction slope of large-scale open pit mine, highway and other demonstration projects as an example, this study analyzed the precipitation, rainfall density, runoff and sediment variation characteristics of 91 rainfalls, and explained the mechanism of vegetation configuration on sediment production on slopes. The results were shown that: (1) the vegetation coverage, early water content and total porosity were the key factors restricting the runoff generation on the slope, among which grey correlation were 0.72, 0.74 and 0.79 respectively. The total porosity, litter thickness and vegetation coverage were the key limiting factors of sediment yield on slope, and their grey correlation degree were 0.64, 0.60 and 0.58 respectively. (2) the comprehensive contribution degree P could reflect the influence of engineering and plant measures on slope sediment production. The analysis showed that the P value of most slopes with engineering and plant measures ranged from 0.31 to 0.77, and the larger the value, the better the effect of reducing soil erosion was. Sediment reduction effect of interlocking bricks greening measure and runoff reduction effect of vegetative carpet greening with coconut fiber measure were the best which P value were separately 0.77 and 0.55. (3) The comprehensive assess coupling model for vegetation-soil system were derived based on vegetation quantitative characteristics, diversity data, soil physicochemical properties and soil and water conservation benefits. Typical protection measures were ordered according to coupling degree (Cd). Three kinds of rocky slopes in mountainous area including metal net hanging combined with spray seeding measure, earth retaining with brick setting measure, ecological bags measure were recommended. Five kinds of soil slopes in mountainous area including grass protection, metal nets within ecological bags, geo-grid cell measure, six arises brick with hollow measure and vegetative carpet greening with coconut fiber measure were recommended. Two kinds of loose slopes including vegetative carpet greening with coconut fiber measure and ecological bags measure were recommended. Six arises brick with hollow measure was recommended in plain soil slopes. In conclusion, the combination of engineering measures and plant measures should be adopted for protection, so as to achieve the purpose of preventing and controlling soil and water loss.
Challenges in creating and exemplary applications of two cross-repository data compilations on sedimentary pollen and permafrost soil temperature
Authors: Wieczorek Mareike , Heim Birgit , Böhmer Thomas , Gebhardt Nadine , Bartsch Annett , Herzschuh Ulrike
Published: March 2020

Large scale analyses of climatic or ecological data are important to understand complex relationships. Often, such data are available in open repositories or national measurement programmes, others are only made available via the responsible researcher. However, merging data from various sources is often not straightforward, due to issues with the data itself or the metadata. Nevertheless, the application of such compilations offers various possibilities. In our working group, two large-scale compilations are currently constructed and applied. The Northern Hemispheric Pollen Compilation consists of data from NEOTOMA, European Pollen Database (EPD), PANGAEA and various authors. With the help of this compilation, we reconstruct climate and vegetation of large spatial and temporal scales. The circumpolar soil temperature dataset consist of data from the Global Terrestrial Network for Permafrost (GTN-P), Roshydromet, PANGAEA, Nordicana D and the National Science Foundation (NSF) Arctic Data Center. In its first version, the compilation has already been successfully applied to validate the ESA CCI Permafrost soil temperature map.

The various sources of errors and problems will be shown by the two compilations of (i) sedimentary pollen data and (ii) soil temperature data. The most general problem and error source are wrong or inaccurate coordinates. These errors arise out of coordinates provided with two decimals only, wrong conversion of DMS to decimal format, wrong coordinates etc. For most analyses, the most exact geographic position is a prerequisite, as e.g. lake size is an important parameter when reconstructing vegetation out of sedimentary pollen data. Sedimentary pollen records not located in a lake according to their given location thus need manual reposition according to the main researcher of a dataset or satellite maps. Further challenges concerning the pollen dataset pose various naming conventions or variable resolution in time. Furthermore, taxonomic resolution varies between datasets, making homogenization necessary.

But also for the soil temperature dataset, extensive checks were necessary, as even quality checked data comprise erroneous values. Furthermore, measured depths vary between datasets. For easy comparisons of soil temperature simulations against data, standardized depths were extracted. In a future step, interpolations between measured depths will help the end-users to extract the exactly needed depths and a compilation of available metadata on e.g. surrounding vegetation and borehole stratigraphy shall be provided.

All compilations will be made available on public repositories.
Quartz grain shape using S.E.M in source-to-sink studies (production and transfer): the case exemple of the Cenozoic of the Paris Basin
Authors: Marie Nicolas , Guillocheau François , Briais Justine , Robin Cécile , Lasseur Eric
Published: March 2020

Understanding the source-to-sink system in sedimentary basins supposes the characterization of two key parameters: the source and the mode of sediment production (physical vs. chemical erosion), as well as the distance of the transfer zone. The shape of the quartz grains may record (1) the chemical vs. physical production of the grain, (2) the processes (eolian vs. fluvial) of sediment transfers, and (3) possible post-deposition emersion and weathering.

The criteria to distinguish chemical erosion are microstructures linked to dissolution (oriented etch pits, solution pits, solution crevasses and scaling) or precipitation (crystalline overgrowths and silica globules, flowers and pellicle). The difference between eolian and fluvial processes is mainly based on the roundness and the type of impact (conchoidal breakage, percussion marks and grooves).

This approach was successfully applied to the Cenozoic of the Paris Basin, a low accommodation sedimentary system (maximum 200 m in 35 Ma) encompassing numerous hiatuses. The source was mainly subjected to chemical erosion, since etching microstructures are often observed overcut by eolian or fluvial transport criteria. This chemical weathering is thought to has been particularly pronounced during Paleocene and Early Eocene times. Eolian transport occurred preferentially during Danian, Lutetian and Bartonian times whereas fluvial transport appears dominant in Danian, Thanetian and Ypresian times. Major emersion marked by in situ laterites growing occurred during Late Paleogene times, Ypresian and Bartonian, with minor ones during Thanetian. This is testified by the superimposition of chemical weathering features on grains smoothed by fluvial and/or eolian transport.
5 Years of Polar Land Ice Velocity and Discharge observed by Sentinel-1
Authors: Wuite Jan , Nagler Thomas , Hetzenecker Markus , Keuris Lars , Libert Ludivine , Rott Helmut
Published: March 2020

Recent years have seen major advancements in satellite Earth observation of polar land ice. Among the most notable are the developments enabled by the Copernicus Sentinel program, including the Sentinel-1 SAR mission. The Sentinel-1 constellation, with its dedicated polar acquisition scheme, has provided the opportunity to derive ice flow velocity of the Greenland and Antarctic ice sheets at an unprecedented scale and temporal sampling. A continuous observational record of the ice sheet margins since October 2014, augmented by dedicated ice sheet wide mapping campaigns, enabled the operational monitoring of key climate variables like ice velocity and glacier discharge. In 2019 additional tracks have been added to the regular acquisition scheme, covering the slow-moving interior of the Greenland Ice Sheet, opening up new opportunities for interferometric applications and permitting to derive monthly ice sheet wide velocity maps. 

Based on repeat pass Sentinel-1 SAR data, acquired in Interferometric Wide (IW) swath mode, we have generated a dense archive of ice velocity maps covering the polar regions and encompassing the entire mission duration, now spanning well over 5 years. Including the latest observational data, we present ice velocity maps of Greenland, Antarctica and other major ice caps, focusing on time series of ice flow fluctuations of major outlet glaciers. The ice velocity maps, complemented by high resolution DEMs and ice thickness data, form the basis for studying ice dynamics and discharge fluctuations and trends at sub-monthly to multi-annual time scales. Our results underscore the value of long-term comprehensive monitoring of the polar ice masses, which is vital for to gain insight for predicting their response to ongoing climate warming.

This poster highlights some of the main achievements and latest developments of 5 years of Sentinel-1 ice flow mapping in the Polar regions facilitated by the ESA Climate Change Initiative (CCI), EU Copernicus Climate Change Service (C3S) and Austrian Space Applications Programme (ASAP). 