bluuebunny/crossref_metadata_2025 huggingface dataset:
Extended TOBIA model for the assessment of deep-seated landslides
Authors: Werner Andrea , Süßer Philip , Enzmann Frieder
Published: March 2020

In order to assess landslide susceptibility, the selection of the controlling factors (i.e., the predictor variables) is crucial. The most important factors for deep-seated landslides are geological settings such as the bedding conditions of rock formations and the distance to faults. We developed a GIS-based semi-automatic method to extract information on the orientation of bedding planes. This method uses information captured by the interpretation of high-resolution digital terrain models (DTMs). In order to calculate dip and dip direction of the bedding planes we have developed the Morpho-Line concept, which uses geometrical information captured by a detailed interpretation of DTMs. To increase the number of data points, additional field measurements were added to the morpho-line data. We have implemented the "accumulated cost" tool, which is similar to thiessen polygons, to interpolate between the data points. This method takes valleys and faults as break lines into account when interpolating bedding orientation values. Dip and dip direction data has been used, in combination with the slope and aspect, to calculate an extended TOBIA model. TOBIA classifies slopes into anaclinal, cataclinal and orthoclinal classes. To obtain a more accurate picture of orthoclinal bedding conditions and their connection to landslides in these areas, we have subdivided the orthoclinal classes. The angle difference between topography and bedding dip has been calculated and divided into classes. According to that model, the highest abundance of landslides is found in slopes classified as cataclinal and orthoclinal. This means that landslides preferably occur where the geological layers are inclined with the slope (cataclinal) or the dip direction is perpendicular to the slope direction (orthoclinal).
Multilayered Crustal Anisotropy in Eastern Tibet Revealed by Receiver Function Data
Authors: Qi Shaohua , Liu Qiyuan , Chen Jiuhui , Guo Biao
Published: March 2020

It is widely accepted that the ongoing India-Asia collision since approximately 50 Ma ago has resulted in the uplift and eastward expansion of the Tibetan Plateau. Yet the interpretations of its dynamic process and deformation mechanism still remain controversial. Distinct models that emphasize particular aspects of the tectonic features have been proposed, including fault-controlled rigid blocks, continuous deformation of lithosphere and lower crust flow.

One possible way to reconcile these models is to investigate crustal deformation at multiple depths simultaneously, as well as crust-mantle interaction. Seismic anisotropy is considered as an effective tool to study the geometry and distribution of subsurface deformation, due to its direct connection to the stress state and strain history of anisotropic structures and fabrics. In the eastern margin of Tibetan plateau, previous studies of seismic anisotropy have already provided useful insights into the bulk anisotropic properties of the entire crust or upper mantle, based on shear wave splitting analyses of Moho Ps and XKS phases.

In this study, we went further to extract anisotropic parameters of multiple crustal layers by waveform inversion of teleseismic receiver function (RF) data from the western-Sichuan temporal seismic array using particle swarm optimization. Instead of directly fitting the backazimuthal stacking of RFs from each station, we translated the RF data into backazimuthal harmonic coefficients using harmonic decomposition technique, which separates the signals (of planar isotropic structure and anisotropy) from the scattering noise generated by non-planar lateral heterogeneity. The constant (k=0) and k=1, 2 terms of backazimuthal harmonic coefficients were used in our inversion. We also fixed the anisotropic model to slow-axis symmetry to avoid ambiguous interpretations.

Our results show that:

(1) Anisotropy with a titled anisotropy axis of symmetry is more commonly observed than pure azimuthal anisotropy in our data, which has been also reported by other RF studies across the surrounding areas of Tibetan plateau.

(2) The trends of slow symmetry axis vary from the upper to lower part of the crust in both Chuandian and Songpan units, indicating the deformation of the upper crust is decoupled from that of the lower crust in these two regions, while the trends are more consistent throughout the crust in the Sichuan basin.

(3) In the upper crust, the trends show a degree of tendency to lie parallel to the major geological features such as the Xianshuihe and Longmenshan faults, exhibiting a fault-controlled deformation or movement. In the middle and lower crust, the trends are NS or NW-SE in Chuandian unit and NE-SW in Songpan unit, which are coincident with the apparent extension directions of the ductile crustal flow.
Effects of earthworm communities on water infiltration in wet soils with energy crops
Authors: Wöhl Lena , Schrader Stefan
Published: March 2020

Maize (Zea mays) is the most commonly cultivated energy crop throughout Europe. However, its cultivation has severe negative effects such as loss of biodiversity and its delivery of ecosystem services, soil compaction and enhanced greenhouse gas emissions. These negative effects tend to be even more pronounced in wet soils such as pseudogleys. As an alternative to annual maize, the perennial cup plant (Silphium perfoliatum) is known to produce a similar yield, especially under waterlogging conditions, while management impacts of its cultivation are assumed to be less harmful to soil biota. Therefore, the aim of the present study was to quantify the provision of ecosystem services (here: control of the soil water balance) delivered by earthworm communities in wet soils under cultivation of cup plant compared with maize and to assess the ecological impact of both energy crops.

Fieldwork was conducted cup plant and maize fields (n = 4) in South Western Germany in spring and autumn 2019. The overall soil type was pseudo gleyic luvisol. All fields are managed for commercial purposes by farmers in the area. Sampling included earthworm extraction with allyl isothiocyanate (AITC) while the infiltration rate was measured simultaneously. Afterwards, hand sorting completed the earthworm sampling. Earthworm species, their abundance and biomass (live weight) were determined.

On average, earthworm abundance and biomass were higher in cup plant fields than in maize fields. In addition, variations in earthworm communities were found. While endogeic earthworms, especially of the genus Aporrectodea, were present in all fields, anecic earthworms were more abundant in cup plant fields. Higher infiltration rates were measured in maize fields. Hints to a correlation between the infiltration rates and the functional earthworm groups were found.

Our results suggest that cup plant fields host overall more diverse earthworm communities. These communities are able to produce a wider range of ecosystem services, even though the link between the infiltration and the crops studied in this stud is not yet validated.
Radar and lightning data assimilation: the impact of different setting options discussed for a heavy precipitation event occurred in Italy.
Authors: Torcasio Rosa Claudia , Federico Stefano , Puca Silvia , Petracca Marco , Vulpiani Gianfranco , Baldini Luca , Dietrich Stefano
Published: March 2020

The forecast of severe events at the local scale still remains challenging because of the multitude of physical processes involved on a wide range of scales. Improving the initial conditions (IC) of numerical weather prediction (NWP) models is a key point for good forecasting. Since limited-area models are nowadays operational at the kilometric scale (< 5 km), the assimilation of data from high-resolution space-time observations is crucial to correctly represent the state of the atmosphere at local scale.

Radar and lightning data are both useful to improve the IC of NWP models for several reasons. Radar data is available with a high spatio-temporal resolution and provides information on hydrometeors and wind, while lightning data locates convection both spatially and temporally accurate.

Recently, Federico et al. (2019) studied the impact of radar reflectivity factor and lightning data assimilation on the Very Short-Term Forecast (VSF) of the RAMS@ISAC NWP model for two intense precipitation events over Italy. They found that, despite an improvement of the rainfall VSF due to the assimilation of lightning and radar reflectivity factor data, the usefulness of the procedure is partially limited by the increase in false alarms, especially in case of high precipitation rates (> 50 mm/3h).

In this work, we apply the methodology proposed by Federico et al. (2019) to an intense precipitation event occurred in Italy in November 2019. The RAMS@ISAC meteorological model is used here, with a horizontal resolution of 3km.

RAMS@ISAC is initialized by a 3D-Var data assimilation scheme that uses both lightning and radar reflectivity factor data. Different 3D-Var data assimilation scheme settings are used to produce different ICs for the RAMS@ISAC model for the specific case.  The sensitivity of the precipitation field prediction to changes in these ICs will be discussed.

Keywords: lightning data assimilation, radar reflectivity factor data assimilation, very short-term forecast, numerical weather prediction

Reference

Federico, S., Torcasio, R. C., Avolio, E., Caumont, O., Montopoli, M., Baldini, L., Vulpiani, G., and Dietrich, S.: The impact of lightning and radar reflectivity factor data assimilation on the very short-term rainfall forecasts of RAMS@ISAC: application to two case studies in Italy, Nat. Hazards Earth Syst. Sci., 19, 1839–1864, https://doi.org/10.5194/nhess-19-1839-2019, 2019.
3D imaging of subglacial lineations under the Rutford Ice Stream, West Antarctica
Authors: Schlegel Rebecca , Booth Adam , Murray Tavi , Smith Andy , Brisbourne Alex , King Ed , Clark Roger , Cornford Steph
Published: March 2020

There are numerous theoretical descriptions of the subglacial conditions (water availability, subglacial geology, flow dynamics) required for the formation of subglacial lineations, such as mega-scale glacial lineations and drumlins, that are known to be indicative of fast ice flow. Traditionally, mapping in de-glaciated areas, both onshore and offshore, has been undertaken using bathymetric maps, satellite data and field observations; here, lineations currently beneath the Rutford Ice Stream (West Antarctica) have been mapped using ground-penetrating radar (GPR) and seismic methods.

The Rutford Ice Stream is more than 2 km thick, of which 1.4 km are located below sea level. The ice surface speed at the grounding line is >1 m per day, and satellite observations indicate a stable ice flow over the past 30 years. The ice-bed interface is assumed to be at the pressure-melting point, while the bed can be divided into a region of soft, deforming sediment, and one of stiff, non-deforming, sediment. Long, elongated lineations, up to ~14 km, up to 150 m high, and 50-500 m wide, are found aligned in the ice-flow direction in the area of the soft sediment, within which the deposition of a drumlin was observed over a period of <10 years. Together with local erosion occurring in the same timescale, this demonstrates the temporal variability of ice stream beds.

To study the detailed architecture of the lineations, 3D grids of GPR data were acquired during the Antarctic Summer Season 2017/18, enabling 3D-processing and imaging of lineations. Using this unique dataset, in conjunction with previous publications plus data from the paleo record, we hope to better understand the possible mechanisms of formation of subglacial lineations as well as subglacial conditions at the Rutford Ice Stream.
Improving PPP static and cinematic positioning by combining GPS and Galileo data.
Authors: Perosanz Felix , Katsigianni Georgia , Loyer Sylvain , Gupta Mini , Santamaria Alvaro , Mercier Flavien
Published: March 2020

The Precise Point Positioning (PPP) technique using the GPS has become a popular alternative to the differential approach. Thanks to the MGEX pilot project of the IGS, precise orbit and clock products from other constellations like Galileo, Beidou, GLONASS are today available. This presentation focusses on GPS and Galileo systems and compares their individual performance to a combined processing.

Resolving GNSS phase observations biases to their correct integer values significantly improves the precision and the accuracy of the estimated parameters. However, PPP with ambiguity resolution (PPP-AR) requires to deal with “hardware” biases at the satellite and receiver level. Nevertheless, several Analysis Centers within the IGS community are providing these biases. Using the orbit, clock and bias products of the GPS and Galileo constellations provided by the CNES-CLS group, we were able to compare PPP and PPP-AR station coordinates repeatability from a network of around 50 stations during 6 months. For both static and cinematic solutions, the hybridized solution significantly exceeds both individual ones.

 

 
Lateglacial and Holocene paleoenvironments: insights from buried black soils in Emilia (Northern Italy)
Authors: Salani Gian Marco , Bianchini Gianluca , Cremonini Stefano , De Feudis Mauro , Vianello Gilmo , Vittori Antisari Livia
Published: March 2020

In Lateglacial and Holocene stratigraphic sequences investigated in the eastern Po Plain (northern Italy), close to Bologna, black horizons are sometimes observed. Earlier paleo-environmental studies concerning this area have not interpreted origin and composition of these black buried horizons. In order to test this hypothesis, we are studying three stratigraphic sequences from Salara (SAL), San Mamolo (SMA) and Marzabotto (MRZ). To emphasize morphological characteristics (e.g., colour and thickness), a pedo-stratigraphic criterion was adopted for each layer observed in all the three stratigraphic sets. Totally, the horizons found are: 15 for SMA (two black), 14 for SAL (two black) and 6 for MRZ (one black); for each layer was sampled 1 kg of soil for the next investigations. Afterwards, the samples were treated in laboratory to carry out i) geochemical analyses of major, minor and trace elements, by XRF-WD Spectrometry, ii) carbon speciation in Organic (TOC) and Inorganic (TIC) fractions, by Soli TOC Cube (elemental analyser working in temperature ramp mode), iii) isotopic (δ13C) analysis, by EA-IRMS System. XRF analysis was necessary to understand how the black horizons are enriched or depleted in major, minor and trace elements compared to the other layers of the stratigraphic sections. Black horizons are enriched in Al2O3 (>14.95 wt%), Fe2O3 (>5.05 wt%), K2O (>2.27 wt%), TiO2 (>0.69 wt%), Ce (>45 mg kg-1), Cr (>148 mg kg-1), V (>91 mg kg-1), and depleted in CaO (<4.52 wt%). In the same way, the Soli TOC Cube analyses were useful to make the carbon speciation for all the layers, demonstrating that black horizons are depleted in TIC (<0.87 wt%) with respect to the other layers. Low calcium and TIC in black horizons indicate that these levels are depleted in carbonates. EA-IRMS measurements were useful to understand the nature of black soils and the different climate conditions existing at the time of pedogenesis. δ13C has been measured for Total Carbon, TIC and TOC, and the values of black horizons are systematically more negative with respect to the other layers. The resulting values are a proxy of the type of vegetation coverage, reflecting the different proportions of C3 and C4 plants. The extremely negative values of black horizons suggest a prevalence of C3 plants during their formations, supporting the initial hypothesis of a connection with cold climatic periods. During these periods water was more acid thus explaining the paucity of carbonate. Pollen analysis is in progress to constrain this interpretation.
Modified hillshade assists in the identification of geomorphologic units of the Moon
Authors: Wang Jiao , Liu Jiayu , Zhang Xinwen
Published: March 2020

Hillshade can greatly enhance the visualization of a surface for spatial analysis, graphical display or terrain extraction. However, its utilization is limited because the results depend on a particular sun azimuth and elevation. The image identification of geomorphologic units in shaded regions of the Moon, similarly, is affected by the azimuth and altitude of the sun. Therefore, utilize the advances while overcome the bias of hillshade, and then apply the modified hillshade to detect the geomorphologic units in shaded regions of the Moon will provide important methodological support for lunar topographic database construction. In this work, we optimize the traditional hillshade by enhancing the visibility of features in terms of scale, relief, orientation, and shape. The enhancement of the above topographic features is achieved by blending hillshaded terrain, curvature, slope, positive openness and sky-view factor into a remote sensing image. We select different study areas to test the modified hillshade, and find that the method proposed in this work can extract the basic geomorphologic units of the Moon in diverse terrain environments. Comparing to using the classic hillshaded digital elevation models, the boundary of various geomorphologic units is augmented and the extraction accuracy is improved using the modified hillshade.
Calculation of corotation electric field based on Van Allen Probes measurements
Authors: Liu Wenlong , Zhang Zhao
Published: March 2020

Corotation electric field is important in the inner magnetosphere topology, which was usually calculated by assuming 24h corotation period. However, some studies suggested that plasmasphere corotation lag exists which leads to the decrease of corotation electric field. In this study, we use electric field measurements from Van Allen Probes mission from 2013 to 2017 to statistically calculate the distribution of large-scale electric field in the inner magnetosphere. A new method is subsequently developed to separate corotation electric field from convection electric field. Our research shows electric field is inversely proportional to the square of L, and, with the assumption of dipole magnetic field, the rotation period of plasmasphere is estimated as 27h, consistent to the results by Sandel et al. [2003] and Burch et al. [2004] with EUV imaging of the plasmasphere. Based on the research, a new empirical model of innermagnetospheric corotation electric field was estibalished, which is significant for a more accurate understanding the large-scale electric field in the inner magnetosphere.
Flood forecasting and alerts in West Africa − experiences from co-developing a pre-operational system at regional scale
Authors: Andersson Jafet , Ali Abdou , Arheimer Berit , Crochemore Louise , Gbobaniyi Bode , Gustafsson David , Hamatan Mohamed , Kuller Martijn , Lienert Judit , Machefer Melissande , Magashi Umar , Mathot Emmanuel , Minoungou Bernard , Naranjo Aytor , Ndayizigiye Tharcisse , Pacini Fabrizio , Silva Pinto Francisco , Santos Léonard , Shuaib Addi
Published: March 2020

Flooding is a rapidly growing concern in West Africa. Several floods have occurred in recent years with severe consequences including loss of lives and damaged infrastructure. Flooding is also projected to increase with climate change. Access to operational forecasts is a critical component in addressing these challenges. This study presents results from our joint efforts to co-design, co-adapt, and co-operate a short- and medium-term operational hydrological forecasting and alert pilot system for West Africa, within the FANFAR project (www.fanfar.eu).

The system has been co-developed through a cycle of workshops, training sessions, and expert exchanges involving representatives from hydrological services, emergency management agencies, river basin organisations, and expert agencies in 17 countries in West and Central Africa. Multi-criteria decision analysis was employed to clarify and prioritize system objectives and configurations. We found that the most highly prioritized objectives were: high accuracy, clear flood risk information, reliable access, and timely production and distribution of the information. Our agile development approach also provided ample opportunities to focus development efforts on the most highly prioritized components, and incorporate stakeholder feedback in the development process.

The system is built on an ICT cloud platform that employs a daily forecasting chain including meteorological reanalysis and forecasting, data assimilation of gauge observations and satellite altimetry, hydrological initialisation and forecasting, flood alert derivation, and distribution through e-mail, SMS, web visualisation and API. The system is designed to enable multiple configurations and integration of several information sources (e.g. different hydrological models, observations, flood hazard thresholds etc.). We present the system configurations, stakeholder-driven adaptations, challenges, and current forecast performance. To our knowledge, the FANFAR system constitutes a significant advancement toward the vision of achieving efficient flood management in West Africa.
Current Risk of Extreme Monsoon Rainfall over India using Large Ensemble Simulations
Authors: Jain Shipra , Scaife Adam A , Dunstone Nick , Smith Doug , Mishra Saroj K , Doherty Ruth
Published: March 2020

India suffers from severe social-economic losses due to floods and droughts during boreal summer (June-September) and therefore there is a growing interest in the current risk of extreme monsoon rainfall. In this analysis, we estimate the risk of flood, drought and unprecedented (outside the range of present observational record) rainfall over India using UNprecedented Simulated Extremes using ENsembles (UNSEEN) method. The UNSEEN is a statistical framework under which the risk of unprecedented rainfall extremes can be estimated using a large ensemble of initialized climate simulations to sample a broad range of internal variability. This is the first application of the method to the hindcasts from multiple coupled atmosphere-ocean models. Under this method, we first test individual models against the observed rainfall record over India and select models that are statistically indistinguishable from observations. The risk of floods, droughts and unprecedented rainfall is then estimated using a large ensemble of summer precipitation simulated by the selected set of models. We note that in present climate the risk of drought is higher than the flood, with droughts being more frequent and intense than the floods. This asymmetry in rainfall extremes is found to be partly due to the asymmetry in El-Nino Southern Oscillation (ENSO) phase, with El Nino reaching higher magnitude more frequently than La Nina. The current risk of record breaking drought (>23% deficit w.r.t climatological mean) is 1.6% whereas the risk for record-breaking flood (>16% excess) is 2.6%. There is even a risk of 30% rainfall deficit that could occur around once in two centuries, which is not yet seen in observations and would have a catastrophic influence on India.
Challenges to peatland restoration in Indonesia
Authors: Suryadiputra Nyoman
Published: March 2020

Challenges to peatland restoration in Indonesia
By 
Nyoman Suryadiputra*) 

Tropical peat swamps in Indonesia are currently experiencing degradation at a very alarming rate. Degradation starts from the time of land clearing (generally burned / uses fire) for both private and community-owned plantations, then a very massive network of drainage canals is built (every 1 Ha of peat land cleared, about 120 m - 700 m long canals are needed). These drainage canals aim to reduce the surface water level of peat so that the land can be planted (especially for) oil palm or acacia. However, peat water release can go out of control, beyond the peatland water level threshold determined by government regulation No 71/2014 on Peatland Management, as a result peat becomes dry, flammable and emits large amount of GHGs. In the long run, if drainage and fires continue, peatlands will experience subsidence, form basins, peat even disappear, flooded during rain and eventually the land becomes unproductive (stranded) and difficult to restore. Such conditions will be more severe and difficult to overcome if in the landscape (peatland hydrology unit) there are various activities by various parties, each of whom has different interests and understandings of peatland use. Regarding the above, restoration of peatland that has been damaged has a very serious challenge. Damage that is getting heavier will have a high level of difficulty and a long recovery time. In addition, the success rate of restoration is determined by benchmarks or recovery criteria that have not been scientifically determined and adopted by the Indonesian government.

Keywords : peatland, degradation, landscape, restoration    

*)  Director of Wetlands International Indonesia
Dependence of late glacial sea-level predictions on 3D Earth structure
Authors: Bagge Meike , Klemann Volker , Steinberger Bernhard , Latinovic Milena , Thomas Maik
Published: March 2020

Glacial isostatic adjustment is dominated by Earth rheology resulting in a variability of relative sea-level (RSL) predictions of more than 100 meters during the last glacial cycle. Seismic tomography models reveal significant lateral variations in seismic wavespeed, most likely corresponding to variations in temperature and hence viscosity. Therefore, the replacement of 1D Earth structures by a 3D Earth structure is an essential part of recent research to reveal the impact of lateral viscosity contrasts and to achieve a more consistent view on solid-Earth dynamics. Here, we apply the VIscoelastic Lithosphere and MAntle model VILMA to predict RSL during the last deglaciation. We create an ensemble of geodynamically constrained 3D Earth structures which is based on seismic tomography models while considering a range of conversion factors to transfer seismic velocity variations into viscosity variations. For a number of globally distributed sites, we discuss the resulting variability in RSL predictions, compare this with regionally optimized 1D Earth structures, and validate the model results with relative sea-level data (sea-level indicators). This study is part of the German Climate Modeling initiative PalMod aiming the modeling of the last glacial cycle under consideration of a coupled Earth system model, i.e. including feedbacks between ice-sheets and the solid Earth.
Testifying SALTMED model using field data in Almaty region, South-east Kazakhstan
Authors: Duisebek Baktybek , Shahgedanova Maria , Wade Andrew , Ragab Ragab
Published: March 2020

South-eastern Kazakhstan is located in the foothills of the Northern Tien Shan Mountains. It has favourable conditions for growing diverse crops but many depend on irrigation. Water is provided by the melt of seasonal snow pack and glaciers.  Crop production in this region is relatively vulnerable to climate change. This study carried experimental measurement with modelling approach to assess and determine how climate change will impact major crop production in the region. The SALTMED crop model was tested for its ability to simulate soil water content (SWC), and final grain yield (Y) for rain-fed winter wheat and irrigated spring maize in 2017 and 2019 respectively. SALTMED is able to simulate SWC with a high degree of accuracy in both field. Simulating maize yield is fairly well, and if an adjustment was made for the locust effect for wheat, simulation would be better. Therefore, since SALTMED does not include the effect of pest on crop yield, a fairer test of the model would estimate the yield without the pest effect. Generally, SALTMED can be applicable in the region.
Meteotsunami research in the Strait of Georgia: Critical observational contributions from a student school network on Vancouver Island
Authors: Rabinovich Alexander , Šepić Jadranka , Thomson Richard
Published: March 2020

Meteorological tsunamis are frequently destructive tsunami-like waves generated by small-scale atmospheric disturbances. Several devastating events occurred recently in various regions of the world oceans, including the Balearic Islands, Sicily, the Adriatic and Black seas, the Great Lakes, the west coast of South Korea, the Netherlands and the Persian Gulf. Although this phenomenon has been actively studied for more than 25 years, the exact mechanism (or mechanisms) responsible for producing these extreme events remains a puzzle. One of the major problems making it difficult to determine the physical process generating meteotsunamis is the absence of a network of simultaneously working precise tide gauges and microbarographs in the affected region. A unique set of high-resolution atmospheric data from the meteorological “school network” of 132 school stations became available for 2008-2019 for the area of southern Vancouver Island and nearby Gulf Islands located in the Strait of Georgia. These data, combined with 1-min sea level data from Canadian Hydrographic Service (CHS) and USA National Oceanic and Atmospheric Administration (NOAA) tide gauges, has enabled us to examine both the spatial and temporal features of mesoscale atmospheric disturbances and coincident properties of the associated sea level oscillations. The data analyses, supported by a series of numerical experiments, has made it possible to reconstruct observed events and to determine the specific atmospheric parameters producing the strongest sea level response in the southern part of the Strait of Georgia. These experiments have helped us to recognize the most effective (and hence, most hazardous) directions and speeds of propagating atmospheric disturbances and to identify “hot spots” along the coast that are under the highest risk of large meteotsunamis.
Reconciliation of catchment travel times derived from tritium and deuterium
Authors: Klaus Julian , Rodriguez Nicolas , Pfister Laurent , Zehe Erwin
Published: March 2020

Catchment travel time distributions (TTDs) are an integrative measure of time-varying flow paths and hydrological processes, commonly derived from tracer data (e.g. 2-H, 3-H). Recently, it has been argued that the use of stable isotopes of O and H compared to tritium neglects the long tails of TTDs and thus truncates our vision on streamflow age. However, the reasons for the truncation of the TTD remain obscured by methodological and data limitations, including different mathematical models and sampling strategies. In this study, we apply composite SAS functions to a forested headwater catchment in Luxembourg, where the complexity of streamflow generation leads to flow paths with highly different TTDs. We calibrate the model with high-frequency (sub-daily) deuterium measurements, as well as nearly 30 tritium stream samples collected over a two-year period. We simulated TTDs based on each tracer individually and jointly. We found that, when using the two tracers in a coherent methodological framework, both tracers result in similar TTD and storage for the studied catchment. We found small differences in the TTDs that might be explained by calculation uncertainties, as well as by the limited sampling frequency for tritium. Using both stable and radioactive isotopes of H as tracers reduced uncertainties in the water age and storage calculations. While tritium and stable isotopes delivered redundant information about younger water, the use of both tracers leveraged the more specific information content of tritium on longer ages in the system. The two tracers had overall different information contents. We found that 30 tritium samples contained more bits of information than approximately 1000 deuterium samples, underlying the importance of complementing stable isotopes studies with tritium data.
Geophysical validation of two years of Sentinel-5p tropical tropospheric ozone columns
Authors: Hubert Daan , Verhoelst Tijl , Compernolle Steven , Keppens Arno , Granville José , Lambert Jean-Christopher , Heue Klaus-Peter , Loyola Diego , Eichmann Kai-Uwe , Weber Mark , Thompson Anne M. , Allaart Marc , Piters Ankie , Johnson Bryan J. , Selkirk Henry B. , Vömel Holger , da Silva Francisco R. , Mohamad Maznorizan , Félix Christian , Stübi René
Published: March 2020

Tropospheric ozone damages ecosystems and causes human health problems. The high spatial and temporal variability of ozone concentrations in the troposphere challenges global observing systems to monitor ozone at all relevant scales. TROPOMI is a nadir-viewing UV-Vis-NIR-SWIR sensor that combines a high spatial resolution, a large swath width and the spectral measurement characteristics required to deliver trace gas data records at unprecedented detail. The first tropospheric data product was publicly released in Fall 2018, a year after launch on the Sentinel-5p platform (S5p). It is based on the convective-cloud differential technique (CCD) to infer 0.5°x1° resolved daily maps of 3-day moving mean values of the tropospheric ozone column (surface to 270 hPa) between 20°S and 20°N in clear-sky conditions. This makes it the highest resolved tropospheric ozone data set currently available for the tropical belt. About two years of data have been collected since the end of the commissioning phase in April 2018.

We present an assessment of the quality of the Sentinel-5p TROPOMI convective-cloud differential tropospheric ozone column data products (O3_TCL OFFL v01.01.05-01.01.07), carried out within the context of ESA’s Sentinel-5p Mission Performance Center (MPC) and the S5PVT AO project CHEOPS-5p. Our assessment of the first two years of TROPOMI data is based on comparisons with (a) quality-assured co-located in-situ measurements by the SHADOZ ozonesonde network, and, (b) satellite data by the GOME-2 and OMI sensors. These well-characterized observational data records serve as references to evaluate the bias and the dispersion of S5p data, and their dependence on influence quantities. Additional visual inspections of the S5p tropospheric ozone maps unveiled non-geophysical structures introduced by the sampling pattern of sensor and clouds. We conclude by assessing the compliance of S5p tropospheric ozone data with respect to mission and user requirements for key data applications.
Shear wave splitting as diagnostics of variable tectonic fabrics across the Eastern Alps – Bohemian Massif contact zone
Authors: Vecsey Luděk , Plomerová Jaroslava , Babuška Vladislav , Working Group the AlpArray-EASI , Working Group the AlpArray
Published: March 2020

We examine lateral variations of shear-wave splitting evaluated from data recorded during the passive seismic experiments AlpArray-EASI (2014-2015) and AlpArray Seismic Network (2016-2019). The swath about 200 km broad and 540 km long along 13.3° E longitude was selected to study the large-scale anisotropy in the mantle lithosphere beneath the Bohemian Massif (BM) and the Eastern Alps. The region is covered by about 200 broad-band temporary and permanent stations.

The shear-wave splitting evaluation consists of several steps: it starts by automated identification and pre-processing of SKS waveforms, filtering and quality check. Then we analyse and, if needed, also correct seismic waveforms for seismometer mis-orientations of all stations used. To improve results of splitting analysis of signals distorted by noise, we carefully apply two splitting methods (eigenvalue, transverse energy). We stack splitting measurements for waves closely propagating within the upper mantle and include particle motion analysis. The modified version of the splitting methods (Vecsey et al., 2008) enables us to retrieve 3-D orientation of large-scale anisotropic structures in the mantle lithosphere and deformations within the sub-lithospheric part of the upper mantle.

Both the evaluated shear-wave splitting parameters and the particle motions are consistent within sub-regions of the Alpine and BM upper mantle and exhibit significant and often sudden lateral changes across the whole region. We relate such changes to sharply bounded anisotropic domains with uniform fossil fabrics in the mantle lithosphere.
The Italian CTBTO Cooperating National Facility (CNF): status of the art
Authors: Pesaresi Damiano , Bertoni Michele , Del Negro Elvio , Parolai Stefano , Comelli Paolo
Published: March 2020

The Italian National Institute for Oceanography and Experimental Geophysics (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - OGS) in Trieste (Italy) is offering, in agreement with the Italian CTBTO National Authority, its Cludinico (CLUD) seismic station as a Cooperating National Facility (CNF) to the CTBTO. As outlined in Pesaresi and Horn (2015) the additional data from the Italian CNF improve the CTBTO location capabilities in the Europe/Middle East area of about 21%, which might be of interest given the actual situation in Iran that breached the nuclear Joint Comprehensive Plan of Action (JCPOA) (Reuters, 2019).

In this presentation, we will illustrate the technical details of the solutions adopted to incorporate the Italian CNF into the CTBTO International Monitoring System (IMS): evaluation of CTBTO certification readiness, CTBTO Standard Station Interface (SSI) hardware and software procurement, test and installation, UPS upgrade, implementation and test of CTBTO communication, security measures.

Reference:

Pesaresi, D., and Horn, N.: Improving CTBTO monitoring capabilities: the Italian proposal for a CNF, CTBT Science and Technology 2015, Vienna, Austria, 22-26 June 2015, T4.1-P31, doi:10.13140/RG.2.1.2862.1927, 2015.

Reuters: "Iran further breaches nuclear deal, says it can exceed 20% enrichment", https://www.reuters.com/article/us-iran-nuclear-idUSKCN1VS05B, last access: 14 January 2020, 2019.
Using RPAS derived images and LiDAR DEM's for the assessment of geomorphic changes in a cultural heritage site affected by recent landslides
Authors: Margarint Mihai Ciprian , Niculita Mihai , Ciotina Mihai Cosmin , Vaculisteanu Georgiana , Linu-Stoilov Valeriu , Tarolli Paolo
Published: March 2020

The recent advances in the acquisition of aerial images using Remotely Piloted Aircraft Systems (RPAS) offer an efficient and low-cost solution for the assessment of geomorphologic changes in areas affected by landslides, gullies and rill erosion, river channel migration, through the creation of accurate Digital Elevation Models (DEM's). Despite many advantages of DEM's obtained through Structure from Motion (SfM) method (resources, availability, high resolution - spatial and temporal), they are suitable for reduced study areas, usually under 100-200 ha, where there is a significant intensity of geomorphic processes and where their effects threaten human assets or heritage.
This study focus on the area of Poiana Mănăstirii Thraco-Getic fortress (2550-2050 yr BP), located in the central part of Moldavian Plateau, Romania. Covering a surface of 12 ha, the fortress is surrounded by a 2-3 m high wall, with a 10 m wide base, and a 1 m deep and 4-6 m wide trench. In its southern part, the landslides destroyed these remnants, and due to the deforestation of the slope in the last 30 years, these processes recorded almost yearly reactivations. The main landslide scarp is affected by a gully system that contributes to the archaeological site degradation.
A DJI Phantom 4 Pro UAV was flown over the study area in October 2019 and acquired images with 80 % side and forward overlap at 20 MP resolution. Visual SFM open source software was used to obtain the point cloud and for georeferencing, a Ground Control Point network was measured with a Trimble GeoExplorer 6000 GPS. In order to detect and to map geomorphic changes, LiDAR point clouds (2012) were used as a reference dataset (with a spatial resolution of 0.25 m, and a vertical accuracy of 0.13 m).
A detailed map showing the changes in topography between 2012 and 2019 has been carried out, supplementing a geomorphological mapping. The most dynamic portions of the landslide are accompanied by dense micro-topographic features like secondary scarps, longitudinal and transversal cracks, which have been mapped using the ortophotoimage. The most dynamic parts of the hillslope are an earthflow, shallow and slumps along with the eastern gully system, piping sinkholes, and the main scarp gullies. The evolution of the landslides and gullies indicate that the southern part of the fortress will be affected in the near future. Alongside the identification of the most active parts of the landslide, we conclude that the entire recently deforested area must return as quick as possible to the initial land use (forest).
Dissolved Neodymium Isotopes Trace Origin and Spatiotemporal Evolution of Modern Arctic Sea Ice
Authors: Laukert Georgi , Bauch Dorothea , Peeken Ilka , Krumpen Thomas , Werner Kirstin , Hathorne Ed , Gutjahr Marcus , Kassens Heidemarie , Frank Martin
Published: March 2020

The lifetime and thickness of Arctic sea ice have markedly decreased in the recent past. This affects Arctic marine ecosystems and the biological pump, given that sea ice acts as platform and transport medium of marine and atmospheric nutrients. At the same time sea ice reduces light penetration to the Arctic Ocean and restricts ocean/atmosphere exchange. In order to understand the ongoing changes and their implications, reconstructions of source regions and drift trajectories of Arctic sea ice are imperative. Automated ice tracking approaches based on satellite-derived sea-ice motion products (e.g. ICETrack) currently perform well in dense ice fields, but provide limited information at the ice edge or in poorly ice-covered areas. Radiogenic neodymium (Nd) isotopes (εNd) have the potential to serve as a chemical tracer of sea-ice provenance and thus may provide information beyond what can be expected from satellite-based assessments. This potential results from pronounced εNd differences between the distinct marine and riverine sources, which feed the surface waters of the different sea-ice formation regions. We present the first dissolved (< 0.45 µm) Nd isotope and concentration data obtained from optically clean Arctic first- and multi-year sea ice (ice cores) collected from different ice floes across the Fram Strait during the RV POLARSTERN cruise PS85 in 2014. Our data confirm the preservation of the seawater εNdsignatures in sea ice despite low Nd concentrations (on average ~ 6 pmol/kg) resulting from efficient brine rejection. The large range in εNd signatures (~ -10 to -30) mirrors that of surface waters in various parts of the Arctic Ocean, indicating that differences between ice floes but also between various sections in an individual ice core reflect the origin and evolution of the sea ice over time. Most ice cores have εNd signatures of around -10, suggesting that the sea ice was formed in well-mixed waters in the central Arctic Ocean and transported directly to the Fram Strait via the Transpolar Drift. Some ice cores, however, also revealed highly unradiogenic signatures (εNd < ~ -15) in their youngest (bottom) sections, which we attribute to incorporation of meltwater from Greenland into newly grown sea ice layers. Our new approach facilitates the reconstruction of the origin and spatiotemporal evolution of isolated sea-ice floes in the future Arctic.
Geometrical and chronological constraints for magnetic signatures in the Central High Atlas
Authors: Mochales Tania , Manar Ahmed , Casas-Sainz Antonio María , Calvin Pablo , Santolaria Pablo , Villalaín Juan José , Ruiz Vicente Carlos , Gil-Imaz Andrés , Torres Sara , Pocoví Andrés , Moussaid Bennacer , Román-Berdiel Teresa , El Ouardi Hmidou , Izquierdo-Llavall Esther , Oliva-Urcía Belén , Marcén Marcos , Bógalo María Felicidad , Sánchez-Moreno Elisa , Herrejón Ángela , Jiménez Ángela ,   CHA Team
Published: March 2020

New residual magnetic map is presented to help decipher the magnetic imprints in the Central High Atlas (CHA) fold-and-thrust belt. The total intensity map shows a main direction mimicking the N070 trend which features the Atlas range. Detailed structural and paleomagnetic studies performed in the selected area demonstrate that similar shortening figures are observed in western and eastern portions. Differences in structural style are the consequence of (i) the inherited structure from the Triassic-Jurassic rifting stage, to Cenozoic inversion, (ii) the differential displacement through the Upper Triassic detachment level and (iii) superposition of cover thrust sheets.

 

Remarkable magnetic anomalies are recorded, from negative values (<-400 nT) in the southern foreland, to positive (>500 nT) in the core of the range. The western sector of the chain is defined by intermediate to high anomalies, probably related to NE-SW basement structures, which favored the emplacement of Triassic CAMP basalts and/or Jurassic gabbro bodies, within the syn-rift sequence. The central part of the range is characterized by high and very high positive anomalies with an irregular distribution, probably linked to Middle-Late Jurassic diapirism produced during extension and intrusion of gabbroid bodies at the core of diapirs, whose structure nucleated NE-SW anticlinal ridges. The eastern sector is characterized by intermediate to low intensity anomalies, likely associated to thick series of basinal Jurassic limestones, whose sequences were stacked (during the Cenozoic compressional stage) by means of kilometer-scale thrusts. Very high positive, linear anomalies seem to be related to Jurassic gabbro intruding directly into the carbonate facies in the eastern sector. Widespread negative anomalies are detected in the foreland southern basin. In this case, the remanent signature could be related to the Paleozoic magmatic provinces.
Multi-Sensor Acoustic Parameter Analysis System for Monitoring and Evaluation of Deep Drilling, Jetting, and Stimulation Operations
Authors: Jamali Shahin , Wittig Volker , Bracke Rolf
Published: March 2020

Acoustic Emission (AE) based systems have been under development and used in this research at Fraunhofer – IEG to monitor, evaluate, and control conventional and novel drilling processes and their pertinent equipment used in geothermal applications. Moreover, new stimulation and high pressure (radial) jetting and drilling operations in deep geothermal reservoirs do heavily rely on such new technologies in order to be able to control them properly and thus, to generate an optimal connection between the main wellbore and the reservoir. As Service intervals and lifetime of machines have long been predicted and monitored via Acoustic Emission (AE) systems, and it is becoming a standard in numerous other industrial operations, AE is known as being a promising technique to be used for such monitoring purposes. AE monitoring is based on the detection and conversion of elastic waves into electrical signals, which are typically associated with a rapid release of localized stress-energy propagating within a given material. Thus, it is passive testing, logging, and analysis method to evaluate changes in the properties and behavior of machines and also mineral type materials such as rocks during operations. Such changes may be induced by drilling, jetting, or other drilling methods and being recorded, located, and evaluated via an AE system. This is the core of Fraunhofer – IEG’S new development, the AE based, so-called Multi-Sensor acoustic parameter analysis (MoUSE) as the primary control and monitoring mechanism during rock breaking, drilling, jetting, and stimulation. AE signals generated during jetting or bit-rock interaction are being monitored and analyzed extensively using novel numerical methods, based on sound analysis and engineering applications. The objective of this paper is to present an alternative approach for QA and QC during drilling, jetting, and stimulation operations based on AE waveforms generated during such continuous processes, including jetting and thermal drilling processes. Initial results of rock breaking tests, including mechanical, and non-contact drilling or jetting, will be presented.