bluuebunny/crossref_metadata_2025 huggingface dataset:
The Norwegian node for the European Multidisciplinary Seafloor and water column Observatory
Authors: Barreyre Thibaut , Fer Ilker , Ferré Bénédicte
Published: March 2020

NorEMSO is a coordinated, large-scale deep-ocean observation facility to establish the Norwegian node for the European Multidisciplinary Seafloor and water column Observatory (EMSO). The project aims to explore the under-sampled Nordic Seas to gain a better understanding of the critical role that they play in our climate system and global ocean circulation. An overarching scientific objective is to better understand the drivers for the temporal and spatial changes of water mass transformations, ocean circulation, acidification and thermo-chemical exchanges at the seafloor in the Nordic Seas, and to contribute to improvement of models and forecasting by producing and making available high quality, near real time data. NorEMSO will achieve this by combining expansion of existing and establishment of new observatory network infrastructure, as well as its coordination and integration into EMSO.

NorEMSO comprises of three main components: moored observatories, gliders, and seafloor and water column observatory at the Mohn Ridge (EMSO-Mohn).

Moored observation systems include an array of four moored observatories located at key positions in the Nordic Seas (Svinøy, Station M, South Cape, and central Fram Strait).

Gliders will be operated along five transects across both the Norwegian and the Greenland Seas to monitor circulation and water mass properties at those key locations. Transects in the Norwegian and Lofoten basins will focus on monitoring the Norwegian Atlantic Current, and a transect in Fram Strait will monitor properties and variability in the return Atlantic Water along the Polar Front in the northern Nordic Seas. In addition, transects in the Greenland and Iceland Seas will address the water mass transformation processes through wintertime open ocean convection, and the southbound transport of surface water from the Arctic Ocean and dense water that feeds the lower limb of the Atlantic Meridional Overturning Circulation in the East Greenland Current.

EMSO-Mohn will establish, at the newly discovered hydrothermal site on the Mohn Ridge, a fixed-point seabed-water-column-coupled and wireless observatory with a multidisciplinary approach – from geophysics and physical oceanography to ecology and microbiology. It is primarily directed at understanding hydrothermal fluxes and associated hydrothermal plume dynamics in the water column and how it disperses in an oceanographic front over the Mohn Ridge.

Following EMSO philosophy, NorEMSO will provide data and platforms to a large and diverse group of users, from scientists and industries to institutions and policy makers. The observations will serve climate research, ocean circulation understanding, numerical operational models, design of environmental policies, and education.
Regional flood forecasting based on the spatio-temporal variation characteristics using hybrid SOM and dynamic neural networks
Authors: Chen Tai-Chen , Chang Li-Chiu , Chang Fi-John
Published: March 2020

The frequency of extreme hydrological events caused by climate change has increased in recent years. Besides, most of the urban areas in various countries are located on low-lying and flood-prone alluvial plains such that the severity of flooding disasters and the number of affected people increase significantly. Therefore, it is imperative to explore the spatio-temporal variation characteristics of regional floods and apply them to real-time flood forecasting. Flash floods are common and difficult to control in Taiwan due to several geo-hydro-meteorological factors including drastic changes in topography, steep rivers, short concentration time, and heavy rain. In recent decades, the emergence of artificial intelligence (AI) and machine learning techniques have proven to be effective in tackling real-time climate-related disasters. This study combines an unsupervised and competitive neural network, the self-organizing map (SOM), and the dynamic neural networks to make regional flood inundation forecasts. The SOM can be used to cluster high-dimensional historical flooding events and map the events onto a two-dimensional topological feature map. The topological structure displayed in the output space is helpful to explore the characteristics of the spatio-temporal variation of different flood events in the investigative watershed. The dynamic neural networks are suitable for forecasting time-vary systems because its feedback mechanism can keep track the most recent tendency. The results demonstrate that the real-time regional flood inundation forecast model combining SOM and dynamic neural networks can more quickly extract the characteristics of regional flood inundation and more accurately produce multi-step ahead flood inundation forecasts than the traditional methods. The proposed methodology can provide spatio-temporal information of flood inundation to decision makers and residents for taking precautionary measures against flooding.

Keywords: Artificial neural network (ANN); Self-organizing map (SOM); Dynamic neural networks; Regional flood; Spatio-temporal distribution
What ground tilt tells us about debris flow parameters
Authors: Wenner Michaela , Walter Fabian , Allstadt Kate , McArdell Brian , Lockhart Andrew
Published: March 2020

Large mass movements cause the surface of the earth to deform, depending on the spatial distribution and magnitude of the mass movement and the response of the ground. In volcanology, tilt measurements are used to study earth surface displacement during volcanic processes such as dyke intrusions and magma chamber collapses. Broadband and long period seismometers also record tilt signals at periods of tens to hundreds of seconds, with the horizontal components being most sensitive to tilt. To obtain tilt from seismic recordings the signal from true ground motion and from apparent ground motion due to tilt have to be seperated. Nevertheless, seismometers have shown similar sensitivities as tiltmeters and are, depending on the type of tiltmeter and study site, less cumbersome to install. In this study, we explore the capability of tilt measurements from surface tiltmeters and broadband seismic sensors to determine debris flow parameters like mass, density and flow velocity. We focus on seismic broadband data recorded within a few meters of the Illgraben torrent in Switzerland. Illgraben’s catchment is one of the most active mass wasting sites in the European Alps, producing several debris flows per year. Our seismic records show clear tilt signals from more than ten debris-flow events in 2018 and 2019, which we compare to data from large-scale laboratory experiments at the U.S. Geological Survey (USGS) debris-flow flume at which broadband seismometers and tiltmeters were installed for six 8-10 m3 experiments in 2016.

To explain our observations, we present a model for the loading response of a layered elastic half-space to a moving surface load. This model can be used to invert our observed tilt signals for the surface load, i.e., the mass, density and/or geometry of the debris flow. To verify our model, we use nearby force plate and flow height measurements at both study sites. We discuss to what extent and under which assumptions, compared to force plate installations, the relatively simple and inexpensive tilt measurements can be used to determine debris flow parameters, which to date require sophisticated equipment.
Surface and subsurface fault mapping in the Yorkshire Wolds, UK
Authors: Vernon Rowan , Ford Jon , Watkinson Katie , Haslam Richard , Woods Mark , Farrant Andrew , Burke Helen , Davis Alice , Lear Jennifer , Tarnanas Harris , Wrathmell Edward
Published: March 2020

The Flamborough Head Fault Zone (FHFZ) marks the southern extent of the Cleveland Basin and the northern margin of the Market Weighton Block, England. It is a regionally-significant structural zone which has undergone a complex history of Mesozoic-Cenozoic extension and compression. It is predominantly comprised of east-west trending faults which form a graben that is dissected by north-south trending faults, including the southern extension to the Peak Trough, the Hunmanby Fault. To the west, FHFZ links with the Howardian Fault System and offshore, in the east, it is truncated by the north-south trending Dowsing Fault. The FHFZ is well exposed and described from coastal cliff sections at Flamborough Head but the inland development of the faults have hitherto been poorly explored predominantly due to limited inland-exposure.

The region around the FHFZ is underlain by the Chalk Group, a 500 m thick limestone succession. The Chalk Group is a principal aquifer that is the main source of water supply in East Yorkshire. The geometry and physical characteristics of the Chalk succession, including the effects of faulting, influence groundwater flow across the region. A range of modern data and recent geological research highlight that considerable changes can be made to the region’s current geological maps and subsurface understanding. Ensuring these features are better-documented is key for up-dating groundwater models to enable more confident decisions about land-use, water management and environmental regulation.

A multi-faceted approach to geological mapping has been undertaken in the region by the British Geological Survey (BGS), in collaboration with the Environment Agency. Remote sensing and field mapping of the superficial deposits has better characterised the extent and nature of these deposits and identified potential recharge ‘windows’ into the bedrock. Remote sensing, targeted field mapping, palaeontological analysis, passive seismic and 2D onshore seismic interpretation have been integrated to produce a new map of the Chalk succession, which reveals the inland extension of the FHFZ in unprecedented detail. Combining these techniques has enabled us to bridge the gap between the surface geology and deeper subsurface structure, increase our understanding of the geology of the region and produce an improved conceptual model at a range of depths which will be used to better manage water resources.
Influences of Joint Persistence and Groundwater on Wedge Failure Potential of Jointed Rock Slope
Authors: Chang Yu-Hsuan , Lin Cheng-Han , Lin Ming-Lang
Published: March 2020

Joint persistence and groundwater are critical factors that influence the stability of rock slope. Persistence dominates the extent of pre-existing potential failure surfaces. Under certain conditions, slope instability may vary with time, as the propagation of existing joints leads to the development of fully persistence failure surfaces. At the same time, groundwater may travel through the fracture network and provides an external force to unstable rock masses, resulting in the damage of rock slope failure hard to predict. In general, when a rock slope consists of two or more sets of joints, the wedge failure often becomes the initial structurally controlled failure of a progressive large landslide. A classic case, which was occurred at a steep cut rock slope on 32.5k, Provincial Highway 7, Taiwan, had been completely recorded with UAV-surveys, field investigations and witness. The landslide first occurred on 13th May 2019 as a wedge failure with the magnitude of the volume of 892 m3 and resulted in a large landslide on 29th July 2019 with the magnitude of the volume of 37234 m3, destroyed the protection measures and roads. According to the field investigation, groundwater was discovered flowing out from the line of intersection of persistence joints, which could be the main reason leads to the wedge failure and the progressive large rockslide. Hence, the couple mechanics-hydraulic behavior in a rock slope should be studied in more detail to mitigate such hazards.

In this study, sandbox model was applied to clarify the effects of the groundwater and joint friction on failures of single rock wedge. In addition, the software 3DEC, which is based on Distinct Element method, was carried out to extent the analysis conditions. The results of sandbox simulations were used to calibrate the performance of the numerical model, especially the coupled hydro-mechanical analysis. The stability of jointed rock slopes under different persistence and various water pressure conditions has been studied. It is believed that the study can enhance the way for stability analysis and monitoring of the potential failure of jointed rock slopes.

Keywords: Wedge failure; Joint persistence; Groundwater; Rock slope stability.

 
Revisiting Lake Garba Guracha, high altitude lake in the Bale Mountains, Ethiopia: reconstructing Late Glacial – Holocene lake level history using δ2H/δ18O biomarker analyses
Authors: Bittner Lucas , Bliedtner Marcel , Grady Dai , Gil-Romera Graciela , Martin-Jones Catherine , Lemma Bruk , Lamb Henry F. , De Jonge Cindy , Meyer Hanno , Glaser Bruno , Zech Michael
Published: March 2020

Our knowledge of East African paleoclimate is largely based on marine core and paleolimnological reconstructions. Accordingly, more humid climatic conditions such as the African Humid Period (AHP) are usually associated with summer insolation-driven increased monsoonal precipitation and the movement of the Congo Air Boundary.

In order to contribute to this discussion and to reconstruct the paleoclimate of the afro-alpine Bale Mountains, Ethiopia, within the DFG Research Unit 2358 ‘The Mountain Exile Hypothesis: How humans benefited from and re-shaped African high-altitude ecosystems during Quaternary climate changes’ we re-cored Lake Garba Guracha. This site represents one of the best dated Late Glacial - Holocene continuous, high altitude (3950 m asl) paleoenvironmental archives in East Africa.
We investigated sugar and lipid biomarkers and their compound-specific stable oxygen and hydrogen isotopic composition (δ18Osugar and δ2Hn-alkane) to infer past hydrological patterns. The δ18Osugar record reflects lake water and can thus be used to reconstruct lake evaporation history.

Our results suggest that a virtually permanent lake overflow existed from about 10 to 7 cal. ka BP, whereas the period from about 7 to 5 cal. ka BP is characterised by increased lake evaporation. We present initial results of δ18Odiatom analyses and organic geochemical and XRF data that document dominant minerogenic input during the Late Glacial and increased input of almost exclusively aquatic organic matter from 11 cal. ka BP on. Reconstructed mean annual temperatures (n=20, -2.2 to 2.5°C), inferred from brGDGT-based proxies, indicate that colder conditions prevailed in the high-altitude Bale Mountain ecosystem during the Younger Dryas.
What are the relationships among ecosystem services in Qinghai-Tibetan Plateau of China
Authors: Hou Yanzhen , Zhao Wenwu Zhao , Liu Yanxu , Hua Ting
Published: March 2020

The Qinghai-Tibetan Plateau (QTP) is a “sensor” and “sensitive area” for climate change in Asia and even the northern hemisphere, and its soil ecosystem services are vital components to all aspects of life in the region and support ecosystem functions and services. Understanding the distribution of regional ecosystem services, the relationship among ecosystem services and the influencing factors is an important prerequisite for the protection and optimization of the ecosystem on the QTP. This study quantitatively analyzed the spatio-temporal distribution and interrelationship of multiple ecosystem services such as soil retention (SR) service, water yield (WY) service, habitat quality (HQ) service, crop supply (CS) and livestock supply (LS) services in the Qinghai-Tibet Plateau (QTP) based on InVEST model, statistical and NPP data. Besides, we explored the influences of temperature, elevation, population density, land use and land cover on the relationship of ecosystem services and put forward the corresponding optimization strategy based on ecosystem services perspective. We found that SR, WY and HQ decreased from the southeast to the northwest, regulating services-supporting services are mainly identified as synergies and CS-HQ and CS-LS are manifested as trade-offs. In addition, natural factors (temperature, elevation) influence the distribution of CS and the level of significance of LS, natural factors and the land-use/land-cove affect the shift in the trade-offs and synergies between regulating services and supporting services, and population density mainly affects the relationship between supporting services and other types of services. Providing that the scale effect of ecosystem service relationships in the QTP, we divided the livestock supply collaborative promotion area, the crop-livestock tradeoff optimization area and the multi-ecosystem service optimization area, then put forward specific suggestions at the city scale. This study could be a step forward to optimizing the balance between provisioning services and supporting services or regulating services in the QTP and implementing ecosystem protection policies effectively.
Mutual information applications to estimate the solar/ geomagnetic signatures in the drought indices in the Danube basin
Authors: Mares Ileana , Dobrica Venera , Mares Constantin , Demetrescu Crisan
Published: March 2020

The climatic condition for the dry or wet situations from 15 meteorological stations in the Danube basin has been evaluated using four indices: Palmer Drought Severity Index (PDSI), Palmer Hydrological Drought Index (PHDI), Weighted PDSI (WPLM) and Palmer Z-index (ZIND).

The overall temporal characteristic of the four indices has been analysed by means of the principal component of the Multivariate Empirical Orthogonal Functions decomposition (PC1-MEOF). Also, a simple drought index (TPPI) calculated as the difference between PC1 of the standardized temperature and precipitation, was considered.

To find the simultaneous influence of both solar and geomagnetic activities on drought indices in the Danube basin, the difference between synergistic and redundant components for each season was estimated, using the mutual information between the analyzed variables. The greater this difference is, the greater the simultaneous signature of the two variables in the drought indices is more significant, than by taking each of the two variables separately.

The solar activity was highlighted by Wolf numbers for the period 1901-2000 and for 1948-2000 by solar radio flux. For both periods the geomagnetic activity was quantified by the aa index.

The most significant results for the 100-year period were obtained for the autumn season for which the two predictors representing solar and geomagnetic activities, if considered simultaneously could be one of the causes that produce extreme hydroclimatic events. The analysis from 1948-2000 revealed that the simultaneous consideration of the two external factors is more significant in the summer and autumn time.
“The Skin of the Earth – Where Life meets Rocks” – A Science Movie
Authors: Übernickel Kirstin , von Blanckenburg Friedhelm , Ehlers Todd A.
Published: March 2020

What forms the landscapes of the Earth with their mountains, rivers, soils - the places we live in? Earth’s surface is shaped when rocks are uplifted by geologic forces, and are then destroyed by rain, ice, and wind that carve landscapes by erosion and weathering. But there is the green layer of life between rocks below and climate above. Do plants with their roots, animals that dig into soil, and the vast number of microorganisms shape the landscapes? Or do minerals, soil, and water provide the environment for life? Or are they both interdependent? Can they together resist the massive climate change imposed by humans today?

Showcasing these complex interactions in an audiovisual format provides a fantastic opportunity for science dissemination, but making a movie is a formidable challenge that scientists are not experienced in. Based on the the German National Science Foundation (DFG)- funded research network “EarthShape – Earth Surface Shaping by Biota”, we produced a movie intended as public outreach for scientists as well as classrooms and a general public audience.

Watch the scientists of the German-Chilean “EarthShape” project study the shaping of the Earth along a climate gradient in Chile, in the National Parks Pan de Azúcar, La Campana, and Nahuelbuta. Take a tour through fascinating landscapes and see the young scientists study the interactions between geology and biology, from the dry Atacama desert to dense forests, and in their sophisticated home laboratories. See how feedbacks control Earths’ climate. The movie is available online in Youtube, including separate process animations, and as Open-Access MP4 resource.

Playlist on Youtube: https://go.daf.li/EarthShape; DOI of the English movie version: https://doi.org/10.2312/gfz.3.3.2019.005
Effect of the 2018 drought on methane and carbon dioxide exchange of northern mire ecosystems
Authors: Rinne Janne , Tuovinen Juha-Pekka , Klemendtsson Leif , Aurela Mika , Holst Jutta , Lohila Annalea , Weslien Per , Vestin Patrik , Peichl Matthias , Tuittila Eeva-Stiina , Heiskanen Lauri , Laurila Tuomas , Li Xuefei , Alekseychik Pavel , Mammarella Ivan , Ström Lena , Crill Patrick , Nilsson Mats
Published: March 2020

In 2018, North-Western Europe experienced very dry and warm summer. These conditions can have considerable effects on the functioning and greenhouse gas exchange of terrestrial ecosystems. Peat-forming wetlands, or mires, are a characteristic component of the North-European boreal landscape, and crucial for long-term carbon storage as well as for methane emission. We have analyzed the effect of the drought on greenhouse gas (GHG) exchange of five North European mire ecosystems in Sweden and Finland in 2018. The low precipitation and high summer temperatures in Fennoscandia led to a lowered water table in majority of the mires. This lowered both carbon dioxide (CO2) uptake and methane (CH4) emission during 2018, turning many of the mires from CO2sinks to sources during this year. The changes in methane emission and total GHG exchange, expressed as CO2equivalent, were significantly correlated with change in water table position. The calculated time-evolving radiative forcing due to the changes in GHG fluxes in 2018 showed that the drought-induced changes in GHG fluxes first resulted in a cooling effect lasting 15-50 years, due to the lowered CH4emission, which was followed by longer-term warming phase due to the lower CO2 uptake in 2018.

 
Saharan Dust and Solar Energy Generation in Europe: Case Study of June 2019
Authors: Hoshyaripour Gholam Ali , Bachmann Vanessa , Filipitsch Florian , Straub Jonas , Foerstner Jochen , Mattis Ina , Wagner Frank , Vogel Heike , Vogel Bernhard
Published: March 2020

Aeolian dust, the most dominant atmospheric aerosol by mass, decreases the solar energy reaching the Earth surface by absorbing and scattering the solar radiation. This energy loss increases mainly with the dust concentration in the atmosphere, which is controlled by the emission, transport and removal of the dust particles. All these processes can vary significantly depending on the convection treatment in the model simulations, thereby affect the solar energy forecast.

This study investigates the dust impacts on solar energy generation within convection-resolving simulations using the next-generation atmospheric modeling system ICON-ART (ICOsahedral Nonhydrostatic with Aerosols and Reactive Trace gases). The simulation set-up includes a global domain with 40 km horizontal resolution with three nests down to 5 km horizontal resolution over North Africa and Europe. The innermost nest resolves convection while other domains are based on parameterized convection. This set-up is used to simulate the period 22-27 June 2019, which is associated with a Saharan dust outbreak in clear sky conditions over North Africa and large parts of Europe. 

Compared to the global simulation, the convection-resolving simulation leads to significantly higher dust optical depth in North Africa. This is related to the elevated coarse mode concentrations due to higher vertical velocities in the convection-resolving simulation. However, dust optical depth over Europe only slightly changes as a large portion of coarse mode particles do not reached Europe due to their large sedimentation velocities. The results are compared with AERONET, ceilometer and radiation measurements.
On the connection between heat waves and large deviations of temperature
Authors: Wouters Jeroen , Galfi Vera Melinda , Lucarini Valerio
Published: March 2020

We use large deviation theory to study persistent extreme events of temperature, like heat waves or cold spells. We consider the mid-latitudes of a simplified yet Earth-like general circulation model of the atmosphere and numerically estimate large deviation rate functions of near-surface temperature averages over different spatial scales. We find that, in order to represent persistent extreme events based on large deviation theory, one has to look at temporal averages of spatially averaged observables. The spatial averaging scale is crucial, and has to correspond with the scale of the event of interest. Accordingly, the computed rate functions indicate substantially different statistical properties of temperature averages over intermediate spatial scales (larger, but still of the order of the typical scale), as compared to the ones related to any other scale. Thus, heat waves (or cold spells) can be interpreted as large deviations of temperature averaged over intermediate spatial scales. Furthermore, we find universal characteristics of rate functions, based on the equivalence of temporal, spatial, and spatio-temporal rate functions if we perform a re-normalisation by the integrated auto-correlation.
Distributed Acoustic Sensing from mHz to kHz: Empirical Investigations of DAS Instrument Response
Authors: Paitz Patrick , Edme Pascal , Schmelzbach Cédric , Doetsch Joesph , Gräff Dominik , Walter Fabian , Lindsey Nathaniel , Chalari Athena , Fichtner Andreas
Published: March 2020

With the upside of high spatial and temporal sampling even in remote or urban areas using existing fiber-optic infrastructure, Distributed Acoustic Sensing (DAS) is in the process of revolutionising the way we look at seismological data acquisition. However, recent publications show variations of the quality of DAS measurements along a single cable. In addition to site- and orientation effects, data quality is strongly affected by the transfer function between the deforming medium and the fiber, which in turn depends on the fiber-ground coupling and the cable properties. Analyses of the DAS instrument response functions in a limited part of the seismological frequency band are typically based on comparisons with well-coupled conventional seismometers for which the instrument response is sufficiently well known to be removed from the signal.

In this study, we extend the common narrow-band analyses to DAS response analyses covering a frequency range of five orders of magnitude ranging from ~4000 s period to frequencies up to ~100 Hz. This is based on a series of experiments in Switzerland, including (1) active controlled-source experiments with co-located seismometers and geophones, (2) low-frequency strain induced by hydraulic injection in a borehole with co-located Fiber-Bragg-Grating (FBG) strain-meters, and (3) local to teleseismic ice- and earthquake recordings with  co-located broadband stations.

Initial results show a site-unspecific, approximately flat instrument response for all experiments.

The initial results suggest that the amplitude and phase information of DAS recordings are sufficient for conventional geophysical methods such as event localisation, full-waveform inversion, ambient noise tomography and even event magnitude estimation. Despite the promising initial results, further engagement by the DAS community is required to evaluate the DAS performance and repeatability among different interrogation units and study sites.
Temporal Stacking of Cross-Correlation for Glacier Offset Tracking
Authors: Li Shiyi , Bernhard Philipp , Hajnsek Irena , Leinss Silvan
Published: March 2020

Offset tracking is one of the most widely applied methods for measuring glacier flow velocities using remote sensing data. It uses the pair-wise cross-correlation of images acquired at two different times to detect offsets between image templates of a certain size. Despite the simplicity and reliability of the method, accurate estimations of glacier velocities are limited by the accountability of features and the noise, e.g. radar speckles in synthetic aperture radar (SAR) images. One way of gaining robust estimations is to increase the size of image templates, but the resolution of obtained velocity field is inevitably depreciate. Furthermore, for templates that only contain extremely weak features with respect to the noise, increasing the size of templates is not helpful as the noise is boosted more than the features.

To overcome these issues, we propose a temporal stacking algorithm that first averages a time series of local cross-correlation functions calculated from a series of consecutive image pairs, and then estimates the averaged velocity from the stacked cross-correlation functions. Assuming the flow velocity of a glacier is constant during a certain time span (e.g. a season), the offsets between consecutive image pairs in the time series ought to be equal. Therefore, the cross-correlation functions can be considered as a time series of signals that record the identical offsets and thus are temporally coherent. Hence, we can temporally stack the signals to enhance the signal-to-noise ratio (SNR) of cross-correlation functions and better estimate offsets from the stacked cross-correlation functions. 

The proposed algorithm is assessed by mapping the flow velocity of the Aletsch Glacier using a time series of about 10 SAR images acquired by TanDEM-X in 2017 with constant revisit time of 11 days. The results show that temporal stacking of cross-correlation functions significantly enhances the spatial coverage and resolution of the obtained velocity fields compared to standard offset tracking using only pair-wise cross-correlation functions. This algorithm promotes the ability of mapping glacier velocities to a new extent with larger spatial coverage and higher spatial resolution, and provides a new perspective of measuring glacier velocities through exploiting the emerging time series data from recent high resolution space-born imaging sensors.
Evaluation of agricultural field traffic by modelling traffic intensity and related soil compaction risk
Authors: Kuhwald Michael , Augustin Katja , Duttmann Rainer
Published: March 2020

Soil compaction by field traffic is one of the main threats to all agricultural soils. Besides lower biomass productivity, compacted soils have a reduced regulation function which affects the air, water and nutrient cycles. To evaluate and mitigate soil degradation by field traffic, it is important to know where, when and to what extent soil compaction may occur during certain traffic events.

This study presents an approach to assess soil compaction risk at the field scale, considering the spatio-temporal changes of soil strengths and the machinery-induced changes in load and stress. Two newly developed models, the field traffic model “FiTraM” and the spatially explicit soil compaction risk assessment model “SaSCiA”, were used to evaluate the individual soil compaction risk for each field traffic activity during the maize cropping season. RTK-GPS data recorded by all farm vehicles served for the spatial calculation of traffic intensity and changing wheel loads at high spatial resolution (< 30 cm). These data were subsequently used for soil compaction risk assessment based on readily available soil and weather data.

Our model results indicated that nearly 95% of a field was trafficked throughout the maize-season; harvest traffic at high wheel load contributed to more than the half of the total trafficked area. Furthermore, the analyses showed that soil compaction risk varies greatly within individual fields. Soil moisture and soil texture variation inside the field results in varying soil strength and, therefore, in varying effects of field traffic on soil functions. Thus, one part of a field can be negatively affected by field traffic through an increase in dry bulk density and a decrease in hydraulic conductivity, while the other part is not affected.

In addition to the spatio-temporal assessment of field traffic intensity and soil compaction risk, the presented approach enables the calculation of maximum allowable wheel load until no harmful soil degradation occurs. Thus, the approach may support farmers in their decision-making for a more sustainable soil management.  
The magnitude of soil erosion of small catchments with different land use patterns under an extreme rainstorm on the Northern Loess Plateau, China
Authors: Wang Nan , Jiao Juying
Published: March 2020

The characteristics of soil erosion under extreme rainstorm conditions can reflect the effect of ecological restoration measures and the rationality of land use patterns in the region. 12 dam-controlled catchments was selected after an extreme rainstorm event occurred in the northern Shaanxi Province on 25-26 July 2017 (called “7.26” rainstorm). Soil erosion intensity in the 12 catchments was obtained by digging up the sedimentation profiles and measuring the sedimentation areas. Using digital orthophoto map and digital terrain model by Unmanned Aerial Vehicle to obtain land-use types and their areas, slope gradients and the distance along the flow path to the edge of the downslope and dam-land. Stepwise regression method was used to analyze the main factors affecting catchment erosion intensity. The results showed that the average sedimentation thickness in the 12 damlands ranged from 0.16 m to 1.67 m and the intensity of soil erosion of the 12 catchments varied from 10295 t km-2 to 49227 t km-2. Soil erosion caused by this rainstorm was 10-50 times of the allowable amount of soil erosion in the Loess Plateau region (1000 t km-2.a) issued by Ministry of Water Resource of the People’s Republic of China (MWR). Stepwise regression analysis shows that, the closer the shape of a catchment to the circle is, the larger the area of slope-cropland in inter-gully land is or the closer the distance between slope-cropland and the dam-land is, the larger the erosion modulus in the catchment would be. What’s more, the presence of cement road up the valleys shoulder line reduced the modulus of soil erosion. Theses findings indicated that the existing ecological conditions in the dam-controlled catchments are not able to resist extreme rainstorm erosion effectively. Optimizing the distribution of land use types in catchments should be the focus of soil erosion control.
Influence of ULS data acquisition characteristics on the achievable stem reconstruction accuracies
Authors: Bruggisser Moritz , Otepka Johannes , Pfeifer Norbert , Hollaus Markus
Published: March 2020

Unmanned aerial vehicles-borne laser scanning (ULS) allows time-efficient acquisition of high-resolution point clouds on regional extents at moderate costs. The quality of ULS-point clouds facilitates the 3D modelling of individual tree stems, what opens new possibilities in the context of forest monitoring and management. In our study, we developed and tested an algorithm which allows for i) the autonomous detection of potential stem locations within the point clouds, ii) the estimation of the diameter at breast height (DBH) and iii) the reconstruction of the tree stem. In our experiments on point clouds from both, a RIEGL miniVUX-1DL and a VUX-1UAV, respectively, we could detect 91.0 % and 77.6 % of the stems within our study area automatically. The DBH could be modelled with biases of 3.1 cm and 1.1 cm, respectively, from the two point cloud sets with respective detection rates of 80.6 % and 61.2 % of the trees present in the field inventory. The lowest 12 m of the tree stem could be reconstructed with absolute stem diameter differences below 5 cm and 2 cm, respectively, compared to stem diameters from a point cloud from terrestrial laser scanning. The accuracy of larger tree stems thereby was higher in general than the accuracy for smaller trees. Furthermore, we recognized a small influence only of the completeness with which a stem is covered with points, as long as half of the stem circumference was captured. Likewise, the absolute point count did not impact the accuracy, but, in contrast, was critical to the completeness with which a scene could be reconstructed. The precision of the laser scanner, on the other hand, was a key factor for the accuracy of the stem diameter estimation. 
The findings of this study are highly relevant for the flight planning and the sensor selection of future ULS acquisition missions in the context of forest inventories.
An integrated approach for monitoring the post-fire responses of Pinus pinaster Aiton
Authors: Niccoli Francesco , De Micco Veronica , Castaldi Simona , Valentini Riccardo , Battipaglia Giovanna
Published: March 2020

In the Mediterranean Basin, fire incidence has increased dramatically during the past decades and fire is expected to become more severe in the future due to climate change. The effects of fires on forest ecosystems can last several years: the survival of fire-injured trees depend not only on the adaptive traits of individual species, but also on the ability of trees to tolerate post-fire environmental constraints.

Several trees, although initially resisting the strong heat injury caused by the high temperatures of the flames, can reduce their vigor and finally die after a few years after fire, due to serious damage at the canopy level or due to the difficult conditions arising in the surrounding stands. The study of long-term trends of the eco-physiological processes in plants subjected to fire are of fundamental importance in planning management actions and restoration strategies of burned areas.

In this context, our research aims to identify and understand the impacts that post-fire conditions can have on the growth and eco-physiology of Pinus pinaster Aiton, through the study of a forest stand hit by a devastating fire that affected the Vesuvius National Park, in Southern Italy, in July 2017. This study combines the dendrochronological analyses with the monitoring of xylogenesis, supported by the measurements in continuum of the eco-physiological parameters of the individual plants through the use of the innovative TreeTalker device.

The results of the dendrochronological analyses showed that, at the end of 2018, despite the strong stress suffered and a significant decrease in growth, the plants showed a very limited mortality rate: only 2-10% of the individuals reduced their vigor. However, preliminary data on xyologenesis, collected from spring 2019 to nowadays, suggest how, after two years, the fire of 2017 is still influencing the cambium activity of individual plants: the productivity and the differentiation kinetics of xylem cells are strongly influenced by the damages suffered at the canopy level.

The monitoring activities will continue for the next few years in order to identify the recovery times of the plant to return to normal vital functions, as well as, eventually, understand the eco-physiological processes that lead to a reduction in productivity or even to death.
Microstructural evolution of amphibolite-eclogite facies quartz veins under low greenschist facies deformation condition
Authors: Bestmann Michel , Huet Benjamin , Grasemann Bernhard , Pennacchioni Giorgio
Published: March 2020

Quartz veins in poly-metamorphic settings often accommodate the latest deformation state and therefore can provide important information. Identification of microfabric (microstructure and crystallographic preferred orientation, CPO) evolution of quartz during mylonitization, and especially of the grain-scale interplay between brittle and crystal-plastic processes, has different relevant implications: e.g., on understanding the efficiency of fluid mobility through deforming quartz that can dramatically influence the rheology and the degree of chemical exchange. However, in order to interpret the microstructure and the related deformation processes it is necessary to relate these especially to the deformation temperature. Particularly the CPO and the Ti-in-qtz geothermometry is used to constrain the deformation temperature. However, both methods have to be applied with great caution because even when many times used some fundamental processes are not fully understood yet.

 

Here we present results from deformed quartz veins from the Prijakt Nappe (Autroalpine Unit, Schober Mountains, Central Eastern Alps). These veins localized ductile shear and eventually seismic faulting (recorded by the occurrence of pseudotachylytes) within Eo-Alpine eclogite-facies shists. The veins formed shortly after the eclogitic peak, but the temperature of their deformation remains unconstrained. CL imaging reveals critical details for understanding the role of microfracturing and fluid-rock interaction during initial stages of shear localization, the onset of dynamic recrystallization and the resetting of the Ti-in-quartz geochemistry. Even when optical-light-microscopy and EBSD analysis indicate crystal plastic deformation by subgrain rotation CL and orientation contrast (OC) imaging gives evidence of brittle stage of deformation at least for some of the deformation microstructure. Microshear zones show a bulk dark-CL, but still bright tones in cores of new recrystallized grains similar to the CL signature of the host coarse quartz crystals. CL dark tones also match with the pattern of subgrain boundaries. This reflects fluid permeability pathways along subgrain and grain boundaries (identified by widespread fluid inclusions) and the associated partial resetting of Ti concentrations. The CPO of the new grains within the micro-shear zones rotate with the sense of shear around the kinematic Y-axis and cannot be related to the activity of specific slip systems. In contrast the partial single girdle of c-axis within the ultramylonite with its elongated substructured grains and its characteristic layered microstructure can be related to the activity of several slip systems. Misorientation axis analysis indicates that prism

 

 

 
Sea-ice edge forecast using damped persistence of probability anomaly
Authors: Niraula Bimochan
Published: March 2020

Accelerated loss of the sea-ice cover and increased human activities in the Arctic highlight the need for meaningful prediction of sea-ice conditions at sub-seasonal to seasonal time scales. There is a large variety in the predictive skill of dynamical forecast systems, which can be benchmarked against reference forecasts based on present and past observations of the ice-edge. However, the simplest types of reference forecasts – persistence of the present state and climatology – do not exploit the observations optimally and thus lead to overestimation of forecast skill. For spatial objects such as the ice-edge location, the development of damped-persistence forecasts that combine persistence and climatology in a meaningful way poses a challenge. We have developed a probabilistic reference forecast method that combines the climatologically derived probability of ice presence with initial (present) anomalies of the ice edge. We have tested and optimized the method based on minimization of the Spatial Probability Score, using observed as well as idealized model data. The damping of persistence takes into consideration the temporal pattern of re-emergence and predictability of ice-extent in the Arctic. The resulting reference forecasts provide a challenging benchmark to assess the added value of dynamical forecast systems.
Calculation of changes in the Ta/Nb ratio in differentiates of granite melt based on experimental data
Authors: Alferyeva Yana , Gramenitskiy Evgeniy
Published: March 2020

A change in the Ta/Nb ratio in acid igneous rocks is related to crystallization differentiation processes. The genesis of rock-forming and accessory minerals, the formation of an aqueous fluid at the magmatic stage, or the separation of another liquid phase from a silicate melt through liquation can lead to a change in the Ta/Nb ratio and an increase in the contents of Ta and Nb in the residual melt. A calculation of the possible change in the Ta/Nb indicator ratio in the residual deeply differentiated granite melt is performed.

We used experimental data from various literature sources (T = 650–800 ºC, P = 1–2 kbar) on the solubility of columbite and tantalite in a silicate melt and on the distribution of Ta and Nb among a coexisting silicate melt, aqueous liquid, and aluminum fluoride melt. The Clarke values of these metals in acid rocks of the Earth’s crust were taken as the initial contents of Ta and Nb in the melt. The calculations were made using the mass balance method. It is shown that the separation of fluid in a closed magmatic system rock-forming minerals–silicate melt–water can lead to an approximately twice increase in Ta/Nb in the residual melt as compared to the initial Clarke value. In the system rock-forming minerals–silicate melt–alumino fluoride melt with the initial content of fluorine close to that in biotite granites, the Ta/Nb ratio in the residual melt can increase to ~1. Successive crystallization of minerals of the isomorphic columbite–tantalite series can lead to Ta/Nb > 2 in the residual melt. Crystallization of biotite causes a significant increase in Ta/Nb but significantly prevents the accumulation of these metals in the residual silicate melt.
Statistical and Dynamical study of the cold winter spells over the Balkan Peninsula.
Authors: Tringa Efstathia , Tolika Konstantia , Kostopoulou Efthimia
Published: March 2020

Extreme temperature values are an issue that concerns every society around the world since their impact can cause serious problems even to public health. During the winter months, southeastern Europe and especially the Balkan Peninsula, is characterized by high temperature variability and is often affected by extreme weather events resulting in the creation of serious socio-economic problems. There is therefore a need to further study the causes that contribute to creation of such cold winter spells, so that in the future there will be the possibility of timely forecasting and therefore alerting in order to better prepare each society. The present work provides an extensive climatic analysis of the cold extreme sequences that occurred in the Balkan Peninsula. This climatology includes temporal variations and classification of extreme cold spells according to their source of creation and their characteristics. More specifically, the aim of this work is to study the temporal and spatial variability of the extreme cold spells and to determine the circulation conditions of the occurrences. Daily temperature data from 20 Balkan stations has been collected from the “European Climate Assessment and Datasets” (https://www.ecad.eu/) for the period 1958-2019 (62 years). A cold spell is defined as a sequence of at least 3 cold days, i.e. when the minimum air temperature is below than the 10th percentile of the probability density function from the observation (i.e. Tmin<P10).  After identifying the extreme cold spells, the above parameters are used to describe each event, namely frequency, duration, severity and intensity. The most intense cold spells of have been studied in a synoptic analysis to investigate their fundamental dynamic characteristics and to examine their association with anomalies in the upper layer of the atmosphere. All in all, the proposed study aims to understand the atmospheric circulation conditions that exist in advance and during the extreme cold spells. In addition, the final concept will investigate to identify possible common circulation types associated with their occurrence so that in the future the early indications of such patterns can contribute the early prediction of corresponding extreme cold spells.