bluuebunny/crossref_metadata_2025 huggingface dataset:
High Resolution WRF Regional Climate Modeling for the Andes-Amazon Transition Region: Model Validation Early Results
Authors: Sierra Juan Pablo , Junquas Clementine , Epinoza Jhan Carlo , Lebel Thierry , Segura Hans
Published: March 2020

The western Amazon and eastern flank of the Andes form what is known as the Amazon-Andes transition region. This region is characterized by the presence of the rainiest area in the Amazon basin with an average precipitation ranging from 6000 to 7000 mm per year. This rainy zone is the result of interactions between large-scale circulation and local features. However, the physical mechanisms controlling this rainfall patterns in the transition region are poorly understood. On the other hand, high precipitation values in the area, along with erosion, sediment transport and the geological mountain uplift help to explain this region as one of the most species-rich terrestrial ecosystems. Nevertheless, accelerated deforestation rates reported both in tropical Andes and central-southern Amazon threat the biodiversity hotspots and can induce alterations in land surface energy and water balances. In this context, the use of regional climate models can shed light on the possible consequences of deforestation on rainfall in the transition region.

The early results presented here are the first step in a work that seeks to gain a better understanding in the mechanisms involved in precipitation generation over the Amazon-Andes transition region, as well as the assessment of deforestation impacts on spatial and temporal rainfall variability during austral summer. The Weather Research and Forecasting (WRF) regional climate model is used with three nested domains. High resolution simulations (1km horizontal grid size) are performed over the key regions of Cuzco and Bolivian slopes. As a perspective,  deforestation scenarios following the land use change trajectory observed during the last decade will be used in future works. The results of this work can help to dimension the consequences of deforestation on key ecosystems such as Andean hotspots.
The impact of denying sea ice information on the predictability of atmospheric processes over the Arctic and at mid-latitude regions
Authors: Ponsoni Leandro , Flocco Daniela , Massonnet François , Delhaye Steve , Hawkins Ed , Fichefet Thierry
Published: March 2020

In this work, we make use of an inter-model comparison and of a perfect model approach, in which model outputs are used as true reference states, to assess the impact that denying sea ice information has on the prediction of atmospheric processes, both over the Arctic and at mid-latitude regions. To do so, two long-term control runs (longer than 250 years) were generated with two state-of-the-art General Circulation Models (GCM), namely EC-Earth and HadGEM. From these two reference states, we have identified three different years in which the Arctic sea ice volume (SIV) was (i) maximum, (ii) minimum and (iii) a representative case for the mean state. By departing from each of these three dates (not necessarily the same for the two models), we generated a set of experiments in which the control runs are restarted both from original and climatological sea ice conditions. Here, climatological sea ice conditions are estimated as the time-average of sea ice parameters from the respective long-term control runs. The experiments are 1-year long and all of them start in January when ice is still thin, snow depth is small, air-ocean temperatures contrast the most and, therefore, the heat conductive flux in sea ice (at the surface) is nearly maximum. To robustly separate the response to degrading the initial sea ice state from background internal variability, each of the two counterfactual experiments (reference and climatological) consists of 50 ensembles members. Threstatedese ensembles are generated by adding small random perturbations to the sea surface temperature (EC-Earth) or to the air temperature (HadGEM) fields. Preliminary results reinforce the importance of having the right sea ice state for improving the (sub-)seasonal prediction of atmospheric parameters (e.g., 2m-temperature and geopotential) and circulation (e.g., Westerlies and Jet Stream) not only over the Arctic, but also at mid-latitude regions.
Warm hole in Pacific Arctic sea ice cover forces mid-latitude Northern Hemisphere cooling during winter
Authors: Tachibana Yoshihiro , Komatsu Kensuke , Alexeev Vladimir , Cai Lei , Ando Yuta
Published: March 2020

In North America and Asia, extreme cold weather characterized the winter of 2017–18. At the same time, the Pacific Arctic regions -- Chukchi and Bering Seas --experienced the historical lowest sea ice extent. Because the shape of the ice-free ocean appears as a hole in the larger ice cover, we refer to this sea ice hole as a warm hole. The jet stream dividing cold Arctic air from warm air deviated from normal zonal patterns northward into the ice-free areas north of the Bering Strait. Large southward jet stream pathways formed over Asia and America, allowing cold air to spread into Asia and the southern areas of North America. We hypothesise that the warm hole and Pacific atmospheric rivers were partially responsible for the cold winter. We used data analyses and numerical experiments to test this hypothesis. We propose a positive feedback mechanism between the sea ice anomaly and atmospheric river activity, with anomalous south winds toward the sea ice anomaly potentially leading to more warm water injected by the wind-driven current through the Bering Strait. Our findings suggest that Poleward propagation of the atmospheric rivers made upper air warm, leading to their upgliding, which further heated the overlying air, causing poleward jet meanders. As a part of this response the jet stream meandered southward over Asia and North America, resulting in cold intrusions.

We speculate that the positive feedback mechanism observed during the 2017–18 winter could recur in future years. This winter may be the first year when the warm hole shifted the dynamics of hemispheric climate to the new state, because ice retreat has not abated, and the warm hole would be expected to appear again and again. This would provide Eastern Eurasia and North America with cold winter in the new era of the warm hole. This study was recently published in Scientific Reports [1].

References

 [1] Tachibana, Y., K. K. Komatsu, V. A. Alexeev, L. Cai, and Y. Ando, Warm hole in Pacific Arctic sea ice cover forced mid-latitude Northern Hemisphere cooling during winter 2017-18, Scientific Reports, 9, 5567, DOI: 10.1038/s41598-019-41682-4 , (2019)

 
Time averaging and stratigraphic unmixing: reconstructing ecological decline in molluscan production (Holocene, Brijuni, NE Adriatic)
Authors: Tomašových Adam , Zuschin Martin , Gallmetzer Ivo , Haselmair Alexandra
Published: March 2020

The northeastern Adriatic seafloor is formed by warm-temperate bioclastic carbonates with coralline algae, bryozoans and mollusks. These sediments represent a mixture of past and present-day production owing to low sedimentation rates and bioturbation. Although low sedimentation rates do not allow resolution of ecological history at centennial or even millennial scales on the basis of raw stratigraphic data, age unmixing based on radiocarbon-calibrated amino acid racemization shows that one of the major molluscan sediment producers – the infaunal suspension-feeder Timoclea ovata  – markedly peaked in production ~5,000 years during the maximum flooding and earliest highstand phase and significantly diminished in abundance during the late highstand phase at Brijuni, with a large proportion of dead shells now present in surface sediments representing shells that are several centuries old. This species still occurs in living assemblages but our analyses indicate that its former production was by several orders of magnitude higher. In contrast, stratigraphic trends in absolute and proportional abundance of this species in ~1.5 m-thick sediment cores show a gradual or a very mild upcore decline, indicating that raw stratigraphic data do not efficiently detect millennial-scale ecological dynamic. The temporal decline in production of Timoclea ovata is associated with an increase in water depth and an increase in sediment-accumulation rate, and led to a transition from molluscan oyster-scallop shell bed to late highstand bryomol sediments.
Estimation of natural background level of Cr(VI) in ultramafic rock related alluvial aquifers of central Greece: Comparison of results by statistical and deterministic preselection method approaches
Authors: Argyraki Ariadne , Pyrgaki Konstantina , Kelepertzis Efstratios , Botsou Fotini , Megremi Ifigeneia
Published: March 2020

The definition of natural background concentration levels (NBLs) of geogenic trace metals in groundwater is a challenging issue, particularly in areas where anthropogenic activities are also present. The estimation of NBLs, in combination with environmental quality standards, in such areas is particularly important for the establishment of relevant groundwater threshold values. Over 100 groundwater samples were collected and analysed from four Cr(VI) impacted, alluvial groundwater bodies of central Greece during two consecutive hydrologic years. A common feature of the examined aquifers is the presence of weathered ultramafic rock material in the alluvial sediments. Most sampled boreholes (79 %) are used for irrigation, whereas 21 % of them are used for domestic drinking water supply. Hexavalent Cr concentrations in groundwater, ranging from below detection limit to 430 μg/L, have been attributed to both geogenic and anthropogenic factors. The scope of the present study is to estimate the NBL of Cr(VI) by using a classical statistical approach and a deterministic preselection method and test the comparability of results. In the statistical approach the distribution of samples versus Cr(VI) concentrations has been explored by using probability plots. In this way, the concentration variations within the examined groundwater bodies can be studied and the presence of sub-populations becomes evident by breaks in the slope. In the instance of the preselection method, the concentrations of a set of additional analyzed parameters in ground water, including major water ions and nitrate as well as dissolved oxygen, have been taken into account in order to categorize the samples into two groups of low and high anthropogenic influence, respectively. The comparability of the results derived by the two approaches are discussed in the context of EU Water Framework Directive.
Current sheets with multi-component plasma in planetary magnetospheres
Authors: Popov Victor , Domrin Vladimir , Malova Helmi , Grigorenko Elena , Petrukovich Anatoly
Published: March 2020

The self-consistent hybrid model of a thin current sheet with a thickness about several proton gyroradii in a space plasma is proposed, taking into account multicomponent collisionless space plasma. Several plasma components are often presented in planetary magnetotails (Hermean, Martian, Terrestrial and other ones). Influence of heavy oxygen ions with different properties on current sheet structure is analyzed. It is shown that high relative concentrations of oxygen ions, as well as their relatively high temperatures and flow drift speeds lead to a significant thickening of the sheet and a formation of an additional embedding scale. For some real parameters the profiles of self-consistent current densities and magnetic field have symmetrical jumps of derivatives, i.e. sharp changes of gradients. The comparison is made with observations in the Martian magnetosphere. The qualitative agreement of simulation results with observational data is shown.
Streamlining Oceanic Biogeochemical Dataset Assembly in Support of Global Data Products
Authors: Burger Eugene , Pfeil Benjamin , O'Brien Kevin , Kamb Linus , Jones Steve , Smith Karl
Published: March 2020

Data assembly in support of global data products, such as GLODAP, and submission of data to national data centers to support long-term preservation, demands significant effort. This is in addition to the effort required to perform quality control on the data prior to submission. Delays in data assembly can negatively affect the timely production of scientific indicators that are dependent upon these datasets, including products such as GLODAP. What if data submission, metadata assembly and quality control can all be rolled into a single application? To support more streamlined data management processes in the NOAA Ocean Acidification Program (OAP) we are developing such an application.This application has the potential for application towards a broader community.

This application addresses the need that data contributing to analysis and synthesis products are high quality, well documented, and accessible from the applications scientists prefer to use. The Scientific Data Integration System (SDIS) application developed by the PMEL Science Data Integration Group, allows scientists to submit their data in a number of formats. Submitted data are checked for common errors. Metadata are extracted from the data that can then be complemented with a complete metadata record using the integrated metadata entry tool that collects rich metadata that meets the Carbon science community requirements. Still being developed, quality control for standard biogeochemical parameters will be integrated into the application. The quality control routines will be implemented in close collaboration with colleagues from the Bjerknes Climate Data Centre (BCDC) within the Bjerknes Centre for Climate Research (BCCR).  This presentation will highlight the capabilities that are now available as well as the implementation of the archive automation workflow, and it’s potential use in support of GLODAP data assembly efforts.
Observations from shallow geothermal modelling case studies in Canada and the UK
Authors: Abesser Corinna , Schincariol Robert , Raymond Jasmin , Garcia Gil Alejandro , Busby Jonathan , Drysdale Ronan , Piatek Al , Giordano Nicolo , Jaziri Nehed , Molson John
Published: March 2020

Global demands for energy efficient heating and cooling systems coupled with rising commitments toward net zero emissions building infrastructure have resulted in wide deployment of shallow geothermal systems and in the continued growth in the global geothermal heat pump (GHP) market. With increasing deployment of these systems in urban areas, there is growing potential and risk for these systems to impact the subsurface thermal regime and to interact with each other or with nearby heat-sensitive subsurface infrastructures.

GHP systems have been studied in urban environments with respect to their effects on the subsurface thermal regime, and various modelling studies have investigated the sensitivity of their performance to key (hydro)geological and operational parameters. The focus of these studies has been on isolated systems, where flow conditions and background subsurface temperatures are assumed to be constant, impacted only by the modelled system itself during its operation. However, less attention has been paid to the effects on GHPs functional efficiency from perturbations in the wider hydrogeological and thermal regime, e.g. due to urbanization, multiple BHEs within tight (residential) clusters or competing subsurface uses requiring pumping of groundwater.

In this paper, we present three numerical modelling case studies, from the UK and Canada, which examine GHP systems response to perturbation of the wider hydrogeological and thermal regime. We investigate the influence of key parameters and different model realisations, e.g. relating to system design, unbalanced thermal ground loads and environmental conditions, on the modelled GHP system efficiencies and thermal interference. We highlight findings that are relevant from an economic point of view but also for regulations. Findings are discussed within the context of the contrasting design and operational pattern typical for the UK / Europe and Canada/ North America.
Intercomparisons Between Lidar and Satellite Instruments in the Middle Atmosphere
Authors: Wing Robin , Hauchecorne Alain , Keckhut Philippe , Godin-Beekmann Sophie , Khaykin Sergey , Martic Milena , Steinbrecht Wolfgang , McGee Thomas J. , Sullivan John , McCullough Emily
Published: March 2020

The comparison of ground and ship-based lidar measurements of atmospheric temperature, ozone, and wind to similar measurements made from orbiting satellites is a unique challenge.   In this talk we will discuss general challenges associated with (i) determining coincidence by compensating for geographic and temporal offsets, (ii) satellite-lidar sampling errors, and (iii) comparing results made by different techniques. 

We will show that comparisons of absolute temperature improve when the ground based measurements are compared to a composite satellite profile, created by a weighted average of multiple profiles from one overpass, instead of comparing to the single satellite profile from the closest approach. 

We discuss the importance of including the variation between consecutive satellite profiles for a given overpass in addition to the given satellite instrument uncertainty when calculating the error budget of the comparisons, even when comparing to single satellite profiles. 

We demonstrate how comparing lidar and satellite measurements of events such as small-scale fast moving gravity waves over a particular geographic region can be affected by instrument averaging kernels.

Illustrative examples we will be showing include lidar measurements made during recent instrument validation campaigns at L’Observatoire de Haute Provence (OHP, 43.93 N, 5.71 E), La Réunion (21.17 S, 55.37 E), Hohenpeißenberg Meteorological Observatory (47.80 N, 11.00 E), and onboard the French Navy Research Ship Monge as well as satellite measurements from  the Microwave Limb Sounder (MLS), the Sounding of the Atmosphere by Broadband Emission Radiometry instrument (SABER), Global Ozone Monitoring by Occultation of Stars (GOMOS), and Atmospheric Dynamics Mission Aeolus (Aeolus).
Statistical significance of trend estimations for integrated water vapor time series obtained from GPS technique: a case study in Europe
Authors: Yuan Peng , Hunegnaw Addisu , Teferle Felix Norman , Kutterer Hansjörg
Published: March 2020

Water vapor is an important medium for the transmission moisture and latent heat in the atmosphere. It is one of the most abundant and dominant greenhouse gases in the atmosphere, which is crucial for global warming. With higher temperatures, the specific humidity will also increase as predicted by the nonlinear Clausius-Clapeyron relationship, indicating a positive feedback loop. Hence, estimation of the trend of Integrated Water Vapor (IWV) in the atmosphere is of great importance for global warming research. However, previous studies have shown that the trends of IWV are usually rather small. Therefore, it is important to estimate the IWV trend and its associated uncertainty with a reasonable mathematical model for the homogenized time series from homogenously reprocessed GPS data sets. Since the 1990s, the Global Positioning System (GPS) has successfully been employed to retrieve IWV with a high temporal resolution, all-weather condition and with global coverage. In this work, we used the hourly GPS Zenith Total Delay (ZTD) time series for 1995.0-2017.0 at 21 European GPS stations derived from a homogeneous data reprocessing. For the conversion of ZTD to IWV, we employed the meteorological variables from ERA5, a state-of-the-art atmosphere reanalysis product newly released by the European Centre for Medium-Range Weather Forecasts (ECMWF). Then, we investigated the influence of noise model assumptions within the mathematical model on the uncertainties of IWV trend estimates. As expected, the results confirmed that the assumption of a white noise only model tends to underestimate the trend uncertainty. A first-order autoregressive process is the preferred mathematical model for a more realistic estimation of the IWV trend uncertainty.
SWARM observations of the artificial ionospheric plasma disturbances and field‐aligned currents induced by the SURA power HF heating
Authors: Lukianova Renata , Frolov Vladimir , Ryabov Alexander
Published: March 2020

It has long been a goal of active experiments to understand the response of the ionosphere to the high-power high-frequency (HF) radio wave pumping. The altitudes of 400-500 km are of particular interest since they correspond to the transition from the region, in which the most intense plasma heating and artificial ionospheric turbulence are observed, to the region where the disturbed plasma escapes to the magnetosphere. No observational data on the properties of plasma turbulence induced by the high-power HF pumping at this altitudinal range existed, until the emergence of a multi-satellite low-orbiting SWARM mission.

A series of experiments were conducted with a conjunction between the midlatitude SURA ionospheric heating facility and the SWARM satellites. We present the first observations made by SWARM on the plasma perturbations and electric currents induced in the F2 region ionosphere by the O‐mode radio wave pumping. In the heated region, significant effects include a localized increase of the electron temperature accompanied by stratification of the electron density and the magnetic signatures of field‐aligned currents (FAC) of 0.01-0.02 μA/m2 densities. The upward FAC is confined within the central part of the artificially perturbed magnetic flux tube, while the return downward current flows through the ambient plasma adjoining to the boundary of the HF-disturbed region. The spatial structure and amplitude of FACs indicate the current system is likely associated with the unipolar diffusion and excitation of eddy electric currents in the topside ionosphere. Similar effects are revealed in the laboratory experiment but not previously observed in space. The spaceborne experimental information is being accumulated and further analysis is underway.

This study was supported by the Russian Foundation for Basic Research, grant 20-05-00166. 
Contractional inheritance and rheology controls in a FTB: the Argentinian Precordillera, Central Andes (30°S)
Authors: Branellec Matthieu , Carrera Nuria , Munoz Josep Anton , Ringenbach Jean-Claude , Callot Jean-Paul
Published: March 2020

The Central Andes (12°S-36°S) stretches over more than 2400km. They are characterized by strong longitudinal and latitudinal segmentation (Sierra Pampeanas, Precordillera, Cordillera Frontal, Cordillera Principal from east to west), each domain having distinctive basement involvement and showing different structural styles. The Argentinian Precordillera, located at 30°S, has long been interpreted as a thin-skinned wedge detached below into the lower part of Paleozoic succession. It makes up a typical Coulomb foreland thrust belt system. However, the impact of the Paleozoic inheritance derived from the various orogenic stages on the current structural style has been overlooked. The Chanic structures that developed in Silurian / Devonian times have been reactivated by the Andean deformation that took place from Oligocene to Plio-Pleistocene times. The current structure of the Precordillera has been the subject of numerous studies in the last decades. Thanks to compilation of this literature and fieldwork, we present a new cross-section considering these 2 superimposed events. This cross-section can be divided into 2 different zones depending on the dominant structures. The western Precordillera involves an Ordovician succession characterized by Chanic superimposed folding phases with cleavage development. On the contrary, in the eastern part, most of the observed structures were developed during Andean orogeny. The structural style is characterized by thrusts faults and penetrative deformation is absent. The Sierras Pampeanas in the East are a Miocene thick-skinned system that makes up a typical broken foreland system. The association of both systems of Precordillera and Sierras Pampeanas delineate an inheritance-controlled original orogenic thin-skinned system that turns to the east into a broad thick-skinned system involving up to Precambrian rocks.
From Chemostat/Retentostat to Soil: Modeling bioavailability limitations on atrazine degradation
Authors: Chavez Rodriguez Luciana , Pagel Holger , Streck Thilo , Ingalls Brian
Published: March 2020

Atrazine has been banned in Europe since 2003, but is still a widely used herbicide in the rest of the world. It presents an environmental threat due to its environmental persistence and ecotoxicity. Although soil bacteria have evolved effective biodegradation pathways, atrazine persists in soils at low concentrations making soils to potential continuous sources of groundwater pollution. Experiments using isotopologues of atrazine in simplified systems (chemostat and retentostat) indicate, that limited mass transfer across the cell membrane controls atrazine degradation at low concentrations. We extended and parameterized an existing mathematical model of atrazine degradation in the chemostat/retentostat system using laboratory data. By integrating this modeling approach into a more complex soil model, the role of mass transfer across bacterial cell membranes can be assessed against other rate limiting processes of atrazine biodegradation in soil at low concentrations.
A Climate Smart Framework for Forecasting Field-level Potential Evapotranspiration and Irrigation Requirement with Numerical Weather Predictions and Satellite Remote Sensing
Authors: Tian Di , Asadi Parisa , Medina Hanoi , Ortiz Brenda , Kesikka Isaya
Published: March 2020

A key challenge for climate-smart water management is timely and reliably forecasting potential evapotranspiration (ETc) and irrigation water requirement (IWR) at field level with high spatial and temporal resolution. In this study, we develop a framework for forecasting ETc and IWR using multi-model numerical weather predictions and harmonized Landsat Sentinel-2 remote sensing product. Multiple numerical weather predictions from The International Grand Global Ensemble (TIGGE) are used as input into the Food and Agriculture Organization (FAO) Penman-Monteith equation to produce reference evapotranspiration (ETo) forecasts. The non-homogeneous Gaussian regression method is used to post-process the ETo forecasts. ETo forecasts are evaluated against meteorological observations and compare with the forecasts from the National Weather Service Digital Forest Database over the contiguous United States. Crop parameters (leaf area index and surface albedo) and crop coefficients are derived from visible and near-infrared images from Harmonized Landsat Sentinel-2 product. The satellite derivations are evaluated against ground crop measurements from agricultural fields in Alabama and California. Potential crop evapotranspiration (ETc) forecasts are estimated using two approaches: 1) crop coefficient-based approach, and 2) crop parameter-based approach with the post-processed ETo forecasts. The ETc and irrigation water requirement (IWR) calculated using the FAO-56 method with observed weather data and field collected crop data are used as observational reference. ETc and IWR forecasts are evaluated against observational references using different metrics. In general, statistical post-processing using non-homogeneous Gaussian regression greatly improved ETo forecasting performance. The crop parameter-based approach showed better performance compared to the crop coefficient approach, contingent upon the choice of TIGGE predictions. The study demonstrates the capability of Harmonized Landsat Sentinel-2 and TIGGE for forecasting ETc and IWR and has implications for informing site-specific climate smart water management.  
Towards coupling fluid flow and rate-and-state friction in compacting visco-poro-elasto-plastic reservoirs
Authors: Goudarzi Mohsen , van Dinther Ylona , Li Meng , de Borst René , Pranger Casper , Gerya Taras , Petrini Claudio , Vossepoel Femke
Published: March 2020

Induced seismicity as a result of natural gas production is a major challenge from both an industrial and a societal perspective. The compaction caused by gas production leads to changes of the effective pressure fields in the reservoir and stress redistributions occur particularly in the surrounding faults. In addition, the strong coupling between fluid flow and solid rock deformations and the role of fluid flow regarding the frictional properties of the faults necessitate a coupled and comprehensive modeling framework. A general and fully coupled thermo-hydro-mechanical finite difference formulation is developed herein and the results are verified against numerical benchmarks. A visco-elasto-plastic rheological behavior is assumed for the bulk material and a return-mapping algorithm is implemented for accurate simulation of the stress evolution. The geometrical features of the faults are incorporated into a regularized continuum framework, while the response of the fault zone is governed by a rate-and-state-dependent friction model. Numerical simulations are provided for large-scale problems and their efficiency is assured through the evaluation of the consistently linearized systems of equations along with the use of advanced numerical solvers and parallel computing. Although the proposed framework is a step towards the modeling of earthquake sequences for induced seismicity applications, the features of the numerical model are highlighted for other applications, including seismic events in subduction settings where the role of fluid flow inside the faults is considerable. Another application of the present, fully coupled hydro-thermo-mechanical formulation is the prediction of the fluid pressurization phenomena, where the frictional heating increases the magnitude of the pore fluid pressure inside the faults, and the resultant degradation of dynamic frictional strength is naturally captured. 
Quantifying the dynamic topography through a combination of basin-averaged erosion rates and geomorphic analysis from the Anti Atlas and Western Meseta (Morocco) transient landscape
Authors: Clementucci Romano , Siame Lionel , Ballato Paolo , Yaaqoub Ahmed , Essaifi Abderrahim , Leanni Laëtitia , Guillou Valery , Faccenna Claudio
Published: March 2020

The topography of the Atlas-Meseta system (Morocco) is the result of Late Cenozoic rejuvenation related to mantle-driven uplift. This recent, large-scale dynamic uplift is testified by the occurrence of uplifted shallow-water marine deposits in the Middle Atlas Mountains and in the Western Meseta, indicating that surface uplift must have started after the Late Miocene (Messinian) at rates of 0.1 to 0.2 mm yr-1. This recent pulse is still recorded by transient river networks and by the presence of uplifted relict landscape. In particular, in the Anti Atlas and Western Maroccan Meseta, the lack of significant Cenozoic crustal shortening and the occurrence of several hundred of meters of mantle-driven uplift, offers the possibility to investigate magnitude, timing and rates of deep-seated uplift. In this study we have combined geomorphic analysis of stream profiles with in situ-produced cosmogenic concentrations (10Be, 26Al) in river sediments and bedrock surfaces (corresponding to relict landscape upstream of knickpoints), in order to decipher the uplift history. Our catchment-mean erosion rates allow us to quantitatively constrain the transient state of landscape and hence to unravel the contribution of regional surface uplift on mountain building processes in Morocco during the Plio-Quaternary.
Partitioning of eddy covariance derived pasture N2O emissions for different sources and respective emission factors
Authors: Ammann Christof , Voglmeier Karl
Published: March 2020

Nitrous oxide (N2O) is a very potent greenhouse gas, and the majority of the emissions are associated with intensive livestock production. The magnitude of the emissions depends on the nitrogen (N) input to the soil, and on grazed pastures the largest share of the emissions is typically originating from the N applied via fertilization and excreta of the grazing animals. The uneven spatial distribution of the excretion leads to emission hot spots on grazing systems and makes the quantification of the gaseous emissions difficult. Micrometeorological methods like the eddy covariance (EC) that integrate emissions over a larger area method are well suited to quantify total field-scale N2O emissions of grazed pastures. But the partioning of emissions for different sources and the determination of source-specific emission factors is still a challenge.

We present results of a 5-year field experiment carried out in western Switzerland. The investigated pasture was grazed by dairy cows in an intensive rotational management. The field was additionally fertilized with organic and mineral fertilizer each year, according to the N requirement of the grassland. The field-scale N2O fluxes were quantified with the EC technique using a fast response Quantum cascade laser spectrometer for N2O concentration measurements. The experimental setup and the environmental conditions resulted in high temporal and spatial dynamics of the N2O fluxes with highest values typically occurring after mineral fertilization events in the summer month. Using N2O background parametrizations retrieved from chamber measurements in one year and subtracting the background emission from the measured N2O fluxes allowed us to calculate excreta-related emission factors (EFs) according to the IPCC guidelines. EFs for fertilizer N input were calculated using a pre-defined time window after the fertilizer was applied. The subtracted background emissions during the fertilization events were calculated from the EC measurements outside this time window. We attribute the observed emissions to the different N inputs and discuss potential reasons for the supposedly higher emissions after mineral fertilizer applications in comparison to organic fertilizer emissions.
Relationships in semantic data cubes
Authors: Mansurov Alexandr , Majlingova Olga
Published: March 2020

Linked data is a method for publishing structured data in a way that also expresses its semantics. This semantic description is implemented by the use of vocabularies, which are usually specified by the W3C as web standards. However, anyone can create and register their vocabulary and register it in an open catalogue like LOV.

There are many situations where it would be useful to be able to publish multi-dimensional data, such as statistics, on the web in such a way that it can be linked to related data sets and concepts. The Data Cube vocabulary provides a means to do this using the W3C RDF (Resource Description Framework) standard. The model underpinning the Data Cube vocabulary is compatible with the cube model that underlies SDMX (Statistical Data and Metadata eXchange), an ISO standard for exchanging and sharing statistical data and metadata among organizations [1].

Given the dispersed nature of linked data, we want to infer relationships between Linked Open Data datasets based on their semantic description. In particular we are interested in geospatial relationships.

 We show a generic approach for relationships in semantic data cubes using the same taxonomies, related dimensions, as well as through structured geographical datasets. Good results were achieved using structural geographical ontologies in combination with the generic approach for taxonomies.

 

[1]     Cyganiak, Reynolds, Tennison:  The RDF Data Cube Vocabulary, W3C Recommendation, 16 January 2014,
Ambient lower mantle structure and composition inferred from seismic tomography, convection models, and geochemistry.
Authors: Shephard Grace E. , Hernlund John , Houser Christine , Trønnes Reidar , Crameri Fabio
Published: March 2020

The lower mantle can be grouped into high, low, and average (i.e., ambient) seismic velocity domains at each depth, based on the amplitude and polarity of wavespeed perturbations (% δlnVs, % δlnVp). Many studies focus on elucidating the thermo-chemical and structural origins of fast and slow domains, in particular. Subducted slabs are associated with fast seismic anomalies throughout the mantle, and reconstructed palaeo-positions of Cenozoic to Mesozoic subduction zones agrees with seismically imaged deep slabs. Conversely, slow wavespeed domains account for the two antipodal LLSVPs in the lowermost mantle, which are potentially long-lived features, as well as rising hot mantle above the LLSVPs and discrete mantle plumes. However, low-amplitude wavespeeds (close to the reference velocity models) are often overlooked By comparing multiple P- and S-wave tomographic models individually, and through “vote maps”, we reveal the depth-dependent characteristics and the geometry of ambient structures, and compare them to numerical convection models. The ambient velocity domains may contain early refractory and bridgmantic mantle with elevated Si/(Mg+Fe) and Mg/Fe ratios (BEAMS; bridgmanite-enriched mantle structures). They could have formed by early basal magma ocean (BMO) fractionation during a period of core-BMO exchange of SiO2 (from core to BMO) and FeO (from BMO to core), or represent cumulates of BMO crystallization with bridgmanite as the liquidus phase. The high viscosity of bridgmanitic material may promote its convective aggregation and stabilise the large-scale, degree-2 convection pattern. Despite its high viscosity, bridgmanitic material, representing a primitive and refractory reservoir for primordial-like He and Ne components, might be entrained in vigorous, deep-rooted plumes. The restriction of a weak seismic signal, ascribed to iron spin-pairing in ferropericlase, to the fast and slow domains, supports the notion that the ambient lower mantle domains are bridgmanitic.
Full scale field testing of temporary rockfall protection measures
Authors: Volkwein Axel , Hofstetter Florian , Hauser Marc
Published: March 2020

Temporary rockfall protection measures are often implemented by using so-called steel palisades. Such elements can described as a steel surface that is supported perpendicular to the slope surface. In the present case, several sheet piling sections are welded onto a steel frame to form an area 1.5m high and 3m long. At the lateral edges of the surface, steel sections, welded together to form a triangle, create the support of the front surface, so that one side of the triangle is parallel to the impact surface and another side is parallel to the slope surface. At the corners close to the ground, massive steel spikes allow penetration into the ground. The weight of a palisade is about 900kg. An example of such a palisade can be found in [1].

The above barriers are in usage since many years. However, their rockfall energy retention capacity has never been evaluated yet. For that reasons, the Swiss Federal Railways launched a project for a deeper understanding of the performance of the palisades; for an adequate selection of the protection measures and a reliable risk analyses with respect to the variety of rockfall events that can be expected at a specific construction site and might cause failure of a structure.

Failure limits of the palisades are expected regarding the following failure scenarios:

tilting of the barrier over the valley side steel spikes

displacement of the barrier due to insufficient action of the steel spikes

failure of the front surface

In this contribution, the above mechanisms are evaluated by means of 1:1 field tests.  A detailed analysis of performance and failure states will be provided. Furthermore, potential solutions for simple but effective reinforcement of the barriers are discussed.

The field tests were carried out on a slope inclined at an angle of about 30 degrees. Test blocks with a minimum weight of 240kg are thrown onto the palisades with the help of a forestry cableway reaching impact speeds of up to 25m/s. The impact energies vary from 12 to 100 kJ. Impact location and impact speed are determined by means of laterally taken high-speed video records with a frame rate of up to 1000fps and a resolution of 800x600pxs. Furthermore, the accelerations in the test body were measured at 1000Hz and – for some of the tests - the acting anchorage forces at 5000Hz.

 
Intra-oceanic subduction initiation recorded by the metamorphic sole of the New Caledonia ophiolite: petrological, structural and age constraints
Authors: Cenki-Tok Bénédicte , Gürer Derya , Chatzaras Vasileios , Collot Julien , Corfu Fernando , Maurizot Pierre
Published: March 2020

Subduction initiation is commonly identified as a major enigma in plate tectonics. Attention to subduction initiation is growing in the community, as is our understanding of the sequences of geologic events that precede and postdate this critical stage of the Wilson cycle. Nevertheless, the direct triggers of subduction initiation and their regional to global consequences remain uncertain. The New Caledonia ophiolite has formed in a supra-subduction zone setting in the vicinity of an active spreading centre. The metamorphic sole, which represents the ancient subduction interface, is locally preserved beneath the ophiolite. Unravelling its tectono-metamorphic record is essential in order to determine the timing of subduction initiation and the tectonic processes operating at the plate interface during the early stages of subduction.  We have sampled and studied amphibole-bearing rocks of the metamorphic sole that crop out in three newly found and three previously known localities that are scattered across the island (160 km * 50 km in size). The amphibolites form laterally discontinuous meter-size lenses that crop out within or beneath the serpentinite sole at the base of the ophiolite nappe.  Preliminary U-Pb zircon ID-TIMS geochronology yields a crystallization age of 56±1 Ma in agreement, but with a narrower timespan compared to previously published data (Cluzel et al., 2012).  We use whole-rock geochemistry, mineral chemistry and thermodynamic modelling to constrain the Pressure-Temperature-time history of the amphibolites.  Microstructural data such as dominant deformation mechanisms, crystallographic preferred orientations, grain size distributions determined by EBSD allow to constrain the deformation processes and rheological behavior of the amphibolites during subduction infancy.

 

Cluzel, D., Jourdan, F., Meffre, S., Maurizot, P., and Lesimple, S., 2012. The metamorphic sole of New Caledonia ophiolite: 40Ar/39Ar, U-Pb, and geochemical evidence for subduction inception at a spreading ridge. Tectonics, VOL. 31, TC3016, doi:10.1029/2011TC003085.
Research progress on the Zhongnan-Liyue Fault Zone in the South China Sea Basin
Authors: Xu Ziying , Wang Jun , Gao Hongfang , Yao Yongjian
Published: March 2020

We give a review of the up-to-date research situation about The Zhongnan-Liyue Fault Zone (ZLFZ), than analyze the spatial distribution and tectonic deformation feature of the ZLFZ based on the geophysical data including topographic, seismic, gravity and magnetic data. The results show that the ZLFZ has obvious north-south segmentation characteristics in in the South China Sea Basin. The north section, which is between northwest sub-basin and east sub-basin, is a narrow zone with the width of ~16 km, and is NNW trend from 18°N,115.5°E to 17.5°N,116°E. Meanwhile ,the south section, which is between southwest sub-basin and east sub-basin, is a wide zone with the width of 60-80 km, and is NNW trend from the east of ZhongshaBank to the west of LiyueBank. The main fault of the ZLFZ is NNW trend along the seamounts ridge of Zhongnan. the ZLFZ of transition region is NNE trend from the north section to the south section. According the sub-basin’s sedimentary thickness and oceanic crust thickness exist obvious difference, on both sides of the ZLFZ, we speculate that the ZLFZ play an important role on geological structure of sub-basin. According to the chang of crustal structure, We speculate that the ZLFZ is at least a crustal fracture zone.

Key words: South China Sea Basin; Zhongnan-Liyue Fault Zone; Spatial distribution; Tectonic deformation 

Foundation item: National Natural Science Foundation of China (41606080, 41576068); The China Geological Survey Program (GZH201400202, 1212011220117, DD20160138, 1212011220116).
The ICELEARNING project - Artificial Intelligence techniques for ice core analyses
Authors: Maffezzoli Niccolò , Baccolo Giovanni , Ferretti Patrizia , Delmonte Barbara , Nisancioglu Kerim , Barbante Carlo
Published: March 2020

The detection of insoluble particles trapped in ice cores, like volcanic and dust particles, pollen grains, foraminifera and diatom assemblages, represents the experimental basis for multiple lines of environmental paleoresearch regarding the atmosphere, the biosphere and volcanology. To date, except for ice core dust, the detection of such particles is achieved through observations by manual microscopy. Artificial Intelligence predictive models are already applied to several research fields within geoscience, but up to date its implementation to ice core science is missing. The recently EU funded Marie Curie ICELEARNING project (2020-2022) aims to develop a two-phase routine for the automatic quantification of insoluble particles trapped in ice cores. The routine is based on a commercial Flow Imaging Microscope producing micro-scale images of insoluble particles from melted ice core samples. The image collection of mineral dust, tephra, pollen and marine foraminifera obtained from natural and/or ad-hoc prepared samples will constitute the training datasets. The images will be then analyzed by Pattern Recognition algorithms developed for automatic particle classification and counting. The routine will be specifically developed in order to be implemented in ice core Continuous Flow Analysis (CFA) systems, thus improving the more traditional methods and potentially providing continuous ice core insoluble particle records. The ICELEARNING methodology is suitable for melted ice core samples and any diluted aqueous sample, thus representing a ground-breaking analytical advancement for a wide range of research fields, from ice core science to marine geology. The innovative routine here presented is automatic and non-destructive, imperative prerequisites for future Antarctic ice core projects.
Hydrology without Dimensions
Authors: Porporato Amilcare
Published: March 2020

Dimensional analysis offers an ideal playground to tackle complex hydrological problems. The powerful dimension reduction, in terms of governing dimensionless groups, afforded by PI-theorem and related self-similarity arguments is especially fruitful in case of nonlinear models and complex datasets. After briefly reviewing these main concepts, in this lecture I will present several applications ranging from hydrologic partitioning (Budyko’s curve) and stochastic ecohydrology, to global weathering rates and soil formation, as well as landscape evolution and channelization. Since Copernicus-dot-org asks me to add at least 25 words to the abstract, I would like to thank the colleagues who supported my nomination and my many collaborators.

 

 