bluuebunny/crossref_metadata_2025 huggingface dataset:
The stratified nature of dense granular flows supported by fluctuation velocities and volume fraction measurements from laboratory flume experiments
Authors: Sarno Luca , Papa Maria Nicolina , Wang Yongqi
Published: March 2020

The dynamics of granular media, involved in several hazardous geophysical phenomena such as debris flows and avalanches, is extremely complex and still represents a hot topic for the scientific community and specialists. When choosing a mathematical tool to describe such flows, depth-averaged models remain the first choice especially in large field-scale applications, while three-dimensional and discrete element models are more complete but very computationally expensive. However, the dynamics variations along the flow depth cannot be described by classical depth-averaged models. With the aim of getting a better insight into the dense regime of granular flows, which is the most common in nature, we report a laboratory investigation where a number of dense dry granular flows with different basal boundary conditions and flow rates are studied in a 2m-long Plexiglas flume. The employed granular medium consists of small spheroidal beads (d≈3mm), made of acetal resin (POM). The flume is instrumented with a high-speed digital camera and a no-flicker planar lamp, so that reliable measurements of the velocity and of the volume fraction at the side wall are obtained by using a multi-pass particle image velocimetry (PIV) approach [Sarno et al., Adv. Powder Tech., 2018] and a stochastic-optical method (SOM) [Sarno et al., Granul. Matter, 2016]. By iteratively decreasing the interrogation window in the PIV analysis down to approximately half the grain size, it is possible to estimate the magnitude of the fluctuation velocities along normal-to-bed and stream-wise directions. Small normal fluctuation velocities and relatively large volume fractions (≈0.6) are observed in the major part of the flow, where the chief resistance mechanism is frictional. At the uppermost region, close to the free surface, slightly larger values of the fluctuation velocities and lower values of the volume fraction are observed, due to the increasingly collisional behavior. These findings indicate that, owing to the particles non-penetration condition and weak collisionality, the mass exchanges from one layer to the neighboring ones are rather limited in the dense regime. Therefore, dense granular flows exhibit a clear stratified nature and, thus, they may be regarded as composed of different superimposed layers, partially coupled each other. It is worth noting that this behavior is considerably different from turbulent incompressible fluids and also from chiefly collisional granular flows, where mass and momentum exchanges are considerable along the entire flow depth. These experimental findings suggest that a multi-layer depth-averaged mathematical approach would be a suitable tool for improving the modeling of these flows without increasing significantly the computational costs.
Intercomparison of global storm resolving (coupled) climate models
Authors: Klocke Daniel ,   DYAMOND Team
Published: March 2020

The DYAMOND (DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains) project is an intercomparison project for global storm resolving models with horizontal resolutions < 5km. In Phase 0, nine models participated in simulating a 40 day period from August 2016 on. Now, Phase 0 of DYAMOND will be complemented by a boreal winter period and atmospher-ocean coupled models with the goal to: (i) compare the representation of the Madden-Julian-Oscillation in this class of models; (ii) investigate the effect of the atmosphere-ocean coupling at storm and ocean-eddy resolving scales on convection and the general circulation; and (III) link to the EUREC4A campaign, which targets meso-scale convection patterns and the coupling to the upper ocean processes. First results from the intercomparison of this new class of climate models will be presented, giving an outlook to the future of climate modelling.
Modeling of the Pohang Earthquake Probability Using the Seismogenic Index
Authors: Shapiro Serge , Ree Jin-Han
Published: March 2020

A strong earthquake of Mw5.5 occurred on 15 November 2017, shortly after finishing borehole fluid injections performed for the geothermal development of the Pohang Enhanced Geothermal System. With a high probability, the earthquake was triggered by these operations. In this work we consider the Pohang Earthquake in the frame of the Seismogenic Index Model. We attempt to estimate the triggering probability of this event as well as a general  probability of triggering of arbitrary-magnitude earthquakes at the Pohang site before and after the termination of the fluid injections. A fluid injection in a point of an infinite continuum is taken here as a prototype of the Pohang situation.

The seismogenic index of the Pohang site is approximately between -2 and -1. During the injection operations, one can observe  a tendency of the
seismogenic index to increase with time. This was possibly  an indication of a gradual involvement of seismically more active zones in the stimulated domain. Especially alarming was the event of Mw3.3 on April 15th of 2017. Probably, this event indicated a jump of the seismogenic index to -1. All injection operations in both boreholes should be stopped after this event.

Our estimate of the probability of the Pohang earthquake is approximately 15%. One of  decisive factors for  this relatively high probability was the low b value. A combination of a low b-value and a rather high seismogenic index made the probability of a hazardous event significant. A termination of all injection operations after the occurrence of the event of M_w3.3 would significantly reduce the probability of an M_w5.5 event down to approximately 3%. An injection termination at M_w2.3 would reduce it down to approximately 1%.

The Pohang earthquake has a clear character of a triggered event. A real-time well developed seismic observation system permitting a precise 3-D event location and a monitoring of the temporal evolution of the geometry of the stimulated volume and of the seismogenic index could potentially help to prevent or to delay the occurrence of such an  earthquake.

This paper provides a simplified consideration based on analytical formulations for an effective homogeneous porous medium and monotonic injection operations. Numerical simulations of more realistic injection configurations,  an analysis of modeling results along the indicated here directions, further enhanced processing and analysis of seismologic records are required for more detailed understanding of processes led to the Pohang event. 
Plant thermal tolerance: a global synthesis for future research
Authors: Geange Sonya , Arnold Pieter , Catling Alexandra , Coast Onoriode , Cook Alicia , Gowland Kelli , Leigh Andrea , Notarnicola Rocco , Posch Bradley , Venn Susanna , Zhu Lingling , Nicotra Adrienne
Published: March 2020

Extreme temperature events are increasing in frequency and intensity across the globe. These extremes, rather than averages, drive species evolution and determine survival by profoundly changing the structure and fluidity of cell membranes, altering enzyme function, and denaturing proteins. Given not only our dependence on agricultural crops and natural vegetation, but also the role of photosynthetic processes within the carbon and hydrological cycles, it is imperative to assess the state of our understanding of the potential impacts of extreme events on plants. Scaling responses from the molecular and organ level to ecosystem function is not without challenge however. There is vast literature on plant thermal tolerance research, but the body of literature is so large, the approaches so disparate and often siloed among disciplines, that research in this field risks floundering at a critical time. We conducted a systematic review of more than 21,500 studies spanning over 100 years of research that yielded almost 1,700 included studies on the tolerance of cultivated and wild land plants to both heat and cold. Our review indicates that most studies on thermal tolerance focus on the cold tolerance of cultivated species (52%) and only a trivial percentage of studies have considered both heat and cold tolerance of any given species (~5%). Combined heat and cold tolerance are important in areas where plants are exposed to extremes of both or may be in the future. This review illustrates the global distribution and concentrations of thermal tolerance studies and the diversity of thermal tolerance methods, ranging from molecular to biochemical, physiological and physical examinations, from transgenic model plants to agricultural and horticultural crops, to natural forest trees, shrubs, and grassland herbs. Critically, it also demonstrates that methods and metrics for assessing thermal tolerance are far from standardised, such that our potential to achieve mechanistic insight and compare across species and biomes is compromised. Without reconciling these issues, the scope for incorporating this critical ecological information into vegetation elements of land surface models may be limited. To aid this, we identify priorities for achieving efficient, reliable, and repeatable research across the spectrum of plant thermal tolerance. These priorities, including meta-analytical approaches and comparative experimental work, will not only further fundamental plant science, but will prove essential next steps if we are to integrate such diverse data on a critical plant functional trait into a usable metric within biogeochemical models.
Source region cluster analysis in the high-altitude measuring site of Chacaltaya with WRF and FLEXPART
Authors: Aliaga Diego , Sinclair Victoria , Qiaozhi Zha , Andrade Marcos , Mohr Claudia , Krejci Radovan
Published: March 2020

Measuring aerosol at high altitude sites is useful as it enables sampling of the free troposphere over long time frames. However, in order to draw conclusions from station measurement data, we need to determine which air mass sources are present at any given sampling time. This task is challenging at mountain sites, due to complex topography which in turn drives complex meteorology. Between December 2017 and May 2018, the Southern hemisphere high ALTitude Experiment on particle Nucleation And growth (SALTENA) campaign was conducted at Chacaltaya in Bolivia at 5240 m a.s.l. The data set obtained in this campaign contains records of nearly all relevant aerosol characteristics and aerosol precursors. To identify the source regions of the observed air masses we performed high resolution (down to 1 km) simulations with the Weather Research and Forecasting Model (WRF). The WRF model output is then used to as input to the Lagrangian particle dispersion model (FLEXPART). FLEXPART simulations are initialised every hour and 20 thousand particles are released per hour and track backwards in time for 96 hours. The FLEXPART footprint output is regridded onto a log-polar cylindrical grid where we perform a ‘K-means’ cluster analysis on the 3D cells defined by the grid. The cells are clustered based on the time series of their source receptor relationship (i.e. emission sensitivities), producing regions (clusters) resolved not only in the horizontal but also the vertical domain. Our results show that regions located close to the station (<100km) have a low but persistent influence with diurnal variations and close contact to the surface. Mid-range regions (100-800km) have the highest influence with a higher percentage of air masses from the free troposphere. Long-range regions (>800km) have a higher influence than the short-range regions but lower than the middle-range regions. Most of the air masses from these long-range regions come from the free troposphere. With this method we have successfully resolved the various air mass influences at the measurement site. The high meteorological resolution and the stochastic nature of FLEXPART are seminal for capturing the transport pathways.
Uncertainty in the modelling of large scale flood events in the Barotse floodplain, Zambia
Authors: Willis Tom , Smith Mark , Cross Donall , Hardy Andrew , Ettritch Georgina , Malawo Happiness , Sinkombo Mweemba , Chalo Cosmas , Thomas Chris
Published: March 2020

The Barotse floodplain in the Western Province of Zambia, is a major feature of the Upper Zambezi River, covering an area of 11,000km2, and is inundated annually by a flood cycle that ranges from minimum values in September, to peak levels in April. The annual flooding of the area provides a number of challenges, and critically is a significant component of the life cycle of mosquitos, the principle vector for the transmission of malaria. A research project, FLOODMAL, has been developed to apply process based modelling approaches to the life cycle of the mosquito in the floodplain. A significant component of this approach is the development of a 1D-2D model which can be used to predict the formation of water bodies that are essential to the mosquito breeding cycle. This research presents the uncertainties associated with developing the flood model, with an emphasis on model performance through simulation time. In a typical model exercise, the calibration of input parameters are associated with ensuring that model performance is optimised for representing the peak of a flood event. This can be at the cost of providing a consistent level of model performance throughout a simulation, which is essential in this research.

Using the LISFLOOD-FP computer code, and TanDEM-X1 terrain data, a baseline model of the Barotse floodplain was developed for the 2009 and 2018 events. A set of initial model runs identified key processes to be represented in the model, including evaporation and infiltration. The calibration of the model was focused on defining parameters for surface roughness, channel roughness, evaporation, infiltration, and defining channel topography. A number of datasets were available for model calibration, such as LandSAT imagery to compare observed and modelled extent at various points throughout the year, and downstream river gauge data. To further understand the uncertainties associated with the modelling, sensitivity analysis was undertaken using an emulator- based approach to define the contribution of the input parameters to overall model variance. The results indicate that parameters that control the movement of water across the floodplain (surface roughness) are generally the most significant of the inputs at all points in the year, although the level of this significance changes at different phases.
Mind matters: A model for mental health awareness and support from the Geological Society of London
Authors: Newton Alicia , Sarney Alexandra , O'Donnell Megan
Published: March 2020

Up to one in four UK adults now experience a mental health issue each year. Meanwhile, the numbers of UK university students reporting a mental health condition rose by a factor of five between 2006 and 2016, reaching two percent, with some higher education institutions reporting that one in four students have accessed or are waiting to access mental health services. There are a number of aspects of work and study in the geological sciences that can contribute to or exacerbate poor mental health, with fieldwork identified as a particular source of stress and worry for students and professionals alike. Without clearly signposted pathways to support mental health in the geosciences, students and professionals may choose to leave the field.

In 2019, the Geological Society of London launched a mental health and wellbeing programme for its own staff, and is now sharing the model, and lessons learned during implementation, with geologists and employers of geologists. Following a mental health awareness course made available to all staff, staff were encouraged to apply to become a certified mental health first aider and/or to serve on the newly created Mental Health and Wellbeing Group. Over a quarter of staff members applied for one or both positions, with 20 percent selected for the group, and four of those members selected to become mental health first aiders. In addition, a member of the senior leadership team trained as a mental health champion. We have also launched a survey of employee attitudes toward and understanding of mental health, and started to deliver a series of stress-reducing activities. Early results include staff members reporting feeling more valued as people and an increased uptake of services offered through the employee assistance programme, which offers confidential support around mental and physical health. We will also assess changes in employee morale and sickness absence following the introduction of the programme. Finally, we offer strategies for proposing and implementing mental health and wellbeing programmes at other geoscience employers.
First Comprehensive Measurements of Emission Rates of Greenhouse Gases, Volatile Organic Compounds and Reduced Sulfur Compounds from a Tailings Pond in the Alberta Oil Sands
Authors: Staebler Ralf , Moussa Samar , You Yuan , Hung Hayley , Moradi Maryam , Leithead Amy , Brickell Peter , Hayden Katherine , Mittermeier Richard , Beck James
Published: March 2020

Canada’s Oil Sands Region in northern Alberta contains the world’s largest deposits of commercially exploited bitumen. Extraction of synthetic crude oil from these deposits is a water intensive process, requiring large ponds for water recycling and/or final storage of tailings, already covering a total of over 100 km2 of liquid surface area in the Athabasca Oil sands. The primary extraction tailings ponds primarily contain sand, silt, clay and unrecovered bitumen, while a few secondary extraction ponds also receive solvents and inorganic and organic by-products of the extraction process. Fugitive emissions of pollutants from these ponds to the atmosphere may therefore be a concern, but until recently, data on emission rates for many pollutants, other than a few reported under regulatory compliance monitoring, were sparse. We present here the results from a comprehensive field campaign to quantify the emissions from a secondary extraction pond to the atmosphere of 68 volatile organic compounds (VOCs), 22 polycyclic aromatic compounds (PACs), 8 reduced sulfur compounds as well as methane, carbon dioxide and ammonia. Three micrometeorological flux methods (eddy covariance, vertical gradients and inverse dispersion modeling) were evaluated for methane fluxes to ensure their mutual comparability. Methane and carbon dioxide fluxes were similar to previous results based on flux chamber measurements. Emission rates for 12 PACs, alkanes and aromatic VOCs, several sulfur species, and ammonia were found to be significant. PACs were dominated by methyl naphthalenes and phenanthrenes, while diethylsulfide and  and n-heptane were the dominant reduced sulfur and VOC species, respectively. The role of these previously unavailable emission rates in regional pollutant budgets will be discussed.
Towards a global lithospheric thermal model
Authors: Masterton Sheona , Cheyney Samuel , Green Chris , Webb Peter
Published: March 2020

Temperature and heat flow are key parameters for understanding the potential for source rock maturation in sedimentary basins. Knowledge of the thermal structure of the lithosphere in both a regional and local context can provide important constraints for modelling basin evolution through time.

In recent years, global coverage of heat flow data constraints have enhanced scientific understanding of the thermal state of the lithosphere. However, sample bias and variability in sampling methods continues to be a major obstacle to heat flow-derived isotherm prediction, particularly in frontier areas where data are often sparse or poorly constrained. Consideration and integration of alternative approaches to predict temperature at depth may allow interpolation of surface heat flow in such data poor areas.   

We have attempted to integrate three independent approaches to modelling temperature with depth. The first approach is based on heat flow observations, in which a 1D steady-state model of the lithosphere is constructed from quality-assessed surface heat flow data, crustal thickness estimates and associated lithospheric thermal properties. The second approach is based on terrestrial (airborne, ground and shipborne) magnetic data, in which the maximum depth of magnetisation within the lithosphere is estimated using a de-fractal method and used as a proxy for Curie temperature depth. The third approach is based on satellite magnetic data and estimates the thickness of the magnetic layer within the lithosphere based on the varying amplitudes of satellite magnetic data, accounting for global variations in crustal magnetisation. Curie temperature depth results from each of these approaches have been integrated into a single global grid, then used to calculate temperature-depth variations through the crust.

We have evaluated our isotherm predictions by comparing them with temperature-depth control points and undertook qualitative and quantitative analyses of discrepancies that exist between different modelling approaches; this has provided insights into the origin of such discrepancies that can be integrated into our models to generate a better controlled global temperature-depth result.  

We present details of our methodology and the results of our integrated studies. We demonstrate areas where the independent results are in good agreement, providing vital information for high-level basin screening. We also highlight areas of disagreement and suggest possible causes for these discrepancies and potential resolutions.
Study of accuracy and sensing volume of a wide range of established and low-cost soil water content probes
Authors: Campo-Bescós Miguel A. , Iturria Iban , Gomez Unai , Gimenez Rafael , Casali Javier , Muñoz-Carpena Rafael
Published: March 2020

Continuous soil moisture content monitoring is key to understand the soil and water flow and transport processes and their impact on a wide range of environmental change and quality processes. Nowadays, there are a wide variety of electromagnetic sensors for estimating soil volumetric content. These include those from established manufacturers (>50€) and low-cost (<50€) amateur electronics enthusiasts with open-source projects. For each sensor, the manufacturer typically provides both a calibration function and an estimation of the sensing volume of the device. The objective of this work is to evaluate the performance –regarding the accuracy and effective sensing volume– of a wide variety of soil water sensors and to compare these results with those provided originally by the respective manufacturer. Twenty-five different electromagnetic sensors representative of the current best-known commercial (19) and the low-cost brands (6) were tested in the laboratory using 3 soils of contrasting texture. Benchmark values for comparison were obtained by the gravimetric method. The sensing volume for each probe was characterized by recording readings while the probes approached a water surface. The Root Mean Square Errors of the sensors ranged from 0.02 to 0.10 cm3/cm3, and the sensing volume of the different probes exhibited a large variability, ranging from 0.5 to 1500 cm3. Importantly, the probes evaluated in laboratory conditions showed different errors for each soil type. The loamy soil readings presented the smallest errors, followed by sandy and clayey soils. No statistically significant differences were found in measurement accuracy between low-cost and higher-priced probes. From the study of the sensing volume explored, with the exception of one case, it can be concluded that the low-cost probes generally explore a smaller volume than the established probes. The selection of the appropriate probe based on its sensing value could be important for different types of risk analysis and management applications.
Seismic noise characteristics in Chinese mainland
Authors: Wang Fang , Wang Weitao , Long Jianfeng , Mu Leiyu
Published: March 2020

Using the three-component continuous waveform recordings of 880 broadband seismic stations in China Seismic Network from January 2014 to December 2015, we calculated power spectral densities and probability density functions over the entire period for each station，and  investigated the characteristics of seismic noise in Chinese mainland. The deep analysis on the vertical recordings  indicates that the spatial distribution of noise levels is characterized by obvious zoning for different period bands.  Densely populated areas have higher short-period noise level than sparsely populated ones, suggesting that short-period noise is related to the intensity distribution of human activities such as transportation and industry. Meanwhile，the short-period noise level near the basin is higher than the mountainous areas，which is probably caused by the amplification effect of the sedimentary layer. The microseism energy  gradually decreases from the southeastern coastal lines to the inland regions. Furthermore, horizontal-component noise level  showed a striking constrast with the vertical component at microseismic and long-period bands. In consideration of  the zoning chracteristics and the need of seismic observations, high and low noise models were  acquired for each network , which were proved to be a more effective tool to identify locally abnormal signals including earthquake, instrumental error and various distrubance compared with the global new high and low model. 
Semidiurnal tidal signatures in microbarom infrasound array measurements
Authors: Näsholm Sven Peter , Vorobeva Ekaterina , Le Pichon Alexis , Orsolini Yvan J. , Turquet Antoine L. , Hibbins Robert E. , Espy Patrick J. , De Carlo Marine , Assink Jelle D. , Vera Rodriguez Ismael
Published: March 2020

Recent studies on infrasonic signatures related to atmospheric tides are mostly focused on stratospherically ducted infrasound or on tidal signatures in recorded infrasound signal power.

In the current work, we address microbarom infrasound ducted by mesosphere-lower thermosphere (MLT) waveguides and the associated infrasound apparent velocity (trace velocity) of arrivals at a ground-based array station in northern Norway.

A hypothesis is that the infrasound apparent velocity – which is related to the incidence angle of the wavefront impinging the station – is linked to the altitude of the final refraction of the infrasound waves. This altitude would be affected by the regional MLT tidal pattern.

We apply specialized beamforming and filtering recipes to highlight the MLT-ducted microbarom arrivals and we find semidiurnal patterns in the infrasound apparent velocity measurements.
Inter-comparison of snow depth over sea ice from multiple methods
Authors: Zhou Lu , Stroeve Julienne , Xu Shiming
Published: March 2020

In this study, we compare eight recently developed snow depth products that use satellite observations, modeling or a combination of satellite and modeling approaches. These products are further compared against various ground-truth observations, including those from ice mass balance buoys (IMBs), snow buoys, snow depth derived from NASA's Operation IceBridge (OIB) flights, as well as snow depth climatology from historical observations.

Large snow depth differences between data sets are observed over the Atlantic and Canadian Arctic sectors. Among the products evaluated, the University of Washington snow depth product (UW) produces the overall deepest Spring snow packs, while the snow product from the Danish Meteorological Institute (DMI) provide the shallowest Spring snow depths. There is no significant trend for mean snow depth among all snow products since the 2000s, however, those in regional varies larhely. Two products, SnowModel-LG and the NASA Eulerian Snow on Sea Ice Model: NESOSIM, also provide estimates of snow density. Arctic-wide, these density products show the expected seasonal evolution with varying inter-annual variability, and no significant trend since the 2000s. Compared to climatology, snow density from SnowModel-LG is generally denser, whereas that from NESOSIM is less. Both SnowModel-LG and NESOSIM densities have a larger seasonal change than climatology.

Inconsistencies in the reconstructed snow parameters among the products, as well as differences and with in-situ and airborne observations can in part be attributed to differences in effective footprint and spatial/temporal coverage, as well as insufficient observations for validation/bias adjustments. Our results highlight the need for more targeted Arctic surveys over different spatial and temporal scales to allow for a more systematic comparison and fusion of airborne, in-situ and remote sensing observations.
A Neural Network Model of Three-dimensional Magnetospheric Chorus Waves
Authors: Guo Yingjie , Ni Binbin , Wang Dedong , Shprits Yuri , Fu Song , Cao Xing , Gu Xudong
Published: March 2020

The evolution of chorus waves is important in the inner magnetosphere since it is closely related to the loss and acceleration of radiation belt electrons. In this study, we develop neural-network-based models for upper-band chorus (UBC; 0.5 fce < f <  fce ) waves and lower-band chorus (LBC; 0.05 fce < f < 0.5 fce) waves, where fce is the equatorial electron gyrofrequency. We establish a root-mean-square amplitude database for both UBC and LBC using Van Allen Probe levels 2 and 3 data products from the EMFISIS payload between October 1, 2012 and January 14, 2018. Based on the database, we construct an artificial neural network with corresponding L, magnetic local time, magnetic latitude, solar wind parameters and geomagnetic indices on different time windows as model inputs. Additionally, we adopt several different feature selection techniques to determine the most important features of magnetospheric chorus waves, reduce training or running time and improve the model accuracy. Our study suggests that the model results using the machine learning technique have the great potential to highly improve current understanding of the radiation belt dynamics.
Process dynamics, real time monitoring and early warning at an imminent cliff fall (Hochvogel, Allgäu Alps)
Authors: Leinauer Johannes , Jacobs Benjamin , Krautblatter Michael
Published: March 2020

Costs for (re)installation and maintenance of protective structures are increasing while alpine hazards progressively threaten alpine communities, infrastructure and economics. With climatic changes, anticipation and clever early warning of rock slope failures based on the process dynamics become more and more important. The imminent rock slope failure at the Hochvogel summit (2592 m a.s.l., Allgäu Alps) offers a rare possibility to study a cliff fall at a high alpine carbonate peak during its preparation and until failure. In this real case scenario, we can develop and test an operative and effective early warning system.

The main cleft is two to six metres wide at the summit and at least 60 metres deep at the sides. Several lateral cracks are opening at faster pace and separate different instable blocks. 3D-UAV point clouds reveal a potentially failing mass of 260,000 m³ in six subunits. However, the pre-deformation is yet not pronounced enough to decide on the expected volume. Analysis of historical ortho- and aerial images yields an elongation of the main crack length from 10 to 35 m from 1960 until now. Discontinuous tape extensometer measurements show 35 cm opening of the main cleft between 2014 and 2020 with movement rates up to 1 cm/month. Since July 2018, automatic vibrating wire gauges deliver high-resolution data to an online server. In October 2019, we transferred the system into LoRa with data transmission every 10 min. Automatic warnings via SMS and email are triggered when crossing specific thresholds.

Here we demonstrate long-term process dynamics and 2-years of high-resolution data of a preparing alpine rock slope failure. Corresponding geodetic, photogrammetric, seismic and gravimetric measurements complete the comprehensive measurement design at the Hochvogel. This will help to decipher anticipative signals of initiating alpine rock slope failures and improve future event predictions.
QA4SM: Development of a traceable online satellite soil moisture validation system
Authors: Preimesberger Wolfgang , Scanlon Tracy , Baum Doris , Bakcsa Zoltan , Boresch Alexander , Dorigo Wouter
Published: March 2020

The Quality Assurance for Soil Moisture (QA4SM) service is an online validation tool to evaluate and intercompare the performance of state-of-the-art open-access satellite soil moisture data records (https://qa4sm.eodc.eu). QA4SM implements routines to preprocess, intercompare, store and visualise validation results based on community best practices and requirements set by the Global Climate Observing System and the Committee on Earth Observation Satellite. The focus on traceability in terms of input data, software and validation results improves reproducibility and sets the basis for a community wide standard for future validation studies.

Within the validation framework a number of up-to-date soil moisture datasets are provided. Satellite data include multi-sensor records such as the European Space Agency’s Climate Change Initiative (ESA CCI) and the Copernicus Climate Changes Services (C3S) Soil Moisture datasets and single sensor products e.g. from SMAP, SMOS or Metop ASCAT. Reference data within the service include the full in-situ data archive of the the International Soil Moisture Network (ISMN; https://ismn.geo.tuwien.ac.at/) and land surface model/reanalysis products, e.g. from the European Centre for Medium-Range Weather Forecasts (ECMWF). General validation metrics between dataset pairs (such as correlation or RMSD amongst others) and triples (Triple Collocation) are part of the service. QA4SM allows users to select from a number of input parameters to specify temporal or spatial subsets of data to evaluate and provides options for data filtering, validation of anomalies and the use of different scaling methods.

Within this study we show the current status of the service, present its scope of operation and give an outlook on future developments such as the integration of high resolution data.

This work was supported by the QA4SM project, funded by the Austrian Space Applications Programme (FFG).
How the recently discovered grit crust shapes the Atacama Desert – Combining environmental studies on cryptogams and remote sensing
Authors: Jung Patrick , Lehnert Lukas , Lakatos Michael , Schermer Michael , Baumann Karen , Wraase Luise , Eckhardt Kai-Uwe , Bader Maaike , Leinweber Peter , Bendix Jörg , Büdel Burkhard
Published: March 2020

The Atacama Desert is the driest non-polar desert on Earth, presenting precarious conditions for biological activity. In the arid coastal belt, life is restricted to areas with fog events that cause almost daily wet-dry cycles. In such an area, we discovered a hitherto unknown and unique ground covering biocoenosis dominated by lichens, fungi and algae attached to grit-sized quartz- and granitoid stones (grit crust). In contrast to previously known CGC from arid environments to which frequent cyclic wetting events are lethal, here every fog event is answered by photosynthetic activity of the soil community and thus considered as the desert’s breath. Photosynthesis of the new CGC-type is activated by the lowest amount of water known for such a community worldwide thus enabling the unique biocoenosis to fulfill a variety of ecosystem services such as protection against soil erosion and contributions to accumulation of soil carbon and nitrogen and soil formation through bio-weathering. Using state-of-the-art remote sensing technology, we estimate the total cover of the grit crust and show that the newly discovered organisms cover large areas along the coastal belt of the Atacama Desert.
Putting Paludiculture into Practice – Experiences from field-scale Cattail paludiculture in NE Germany
Authors: Wichmann Sabine , Haldan Kerstin , Köhn Nora , Kuprina Kristina , Neubert Josephine , Tanneberger Franziska , Vogel Telse , Joosten Hans
Published: March 2020

Paludiculture is the productive use of wet peatlands. In contrast to drained peatlands, rewetted peatlands have water levels close to surface, which ensure regulating services similar to those in natural peatland ecosystems. The cultivation of wetland plants provides promising options for sustainable farming on peatland. However, practical experiences with paludiculture is scarce and large-scale implementation remains challenging.

The Paludi-PRIMA project (2019-2022) puts paludiculture into practice. A core task is the establishment and investigation of a Cattail field of ~10 ha on a rewetted, formerly drained fen grassland. We gained valuable experiences on site selection, planning and approval processes (water and nature conservation law) and construction work (site preparation, water management). We planted commercially grown seedlings of two species (T. latifolia, T. angustifolia) with two planting densities (0.5 and 1 plant m-2) using planting machines from forestry. Cattail is adapted to water-saturated soils, enables peat conservation and has a high value creation potential based on the material use of the biomass. Cost data of all implementation steps from site selection to harvest are collected to assess the economic viability in dependence of biomass quality and utilisation options. The field trial is also used for investigations on water demand, nutrient retention and biodiversity, and as a demonstration site for visitors. Mesocosm experiments with Cattail and Reed clones as well as genetic analyses investigate to which extend productivity and biomass quality are determined by species/genotypes, site conditions and management.

Barriers to the implementation of paludiculture are mainly related to the current EU Common Agriculture Policy, the protection of permanent grassland, the consideration of Cattail or Reed stands as protected habitat and the high investment costs. Lessons learned and research results are used to elaborate recommendations for farmers, authorities and policy makers in order to facilitate a large-scale implementation of paludiculture.

Further information: www.moorwissen.de/en/prima
Aggradational Channels on Mars
Authors: Ahmed Joshua , Peakall Jeffrey , Baar Anne W. , Yan Na , Parsons Daniel R. , Balme Matthew R.
Published: March 2020

Sedimentary deposits and geomorphic landforms preserved on the surface of Mars afford scientists a possible insight into the formative conditions of these features and of the planetary climate in the deep past. We use a high-resolution digital elevation model (~1 m/pixel) created from imagery captured using the High Resolution Imaging Science Experiment (HiRISE) camera on board the Mars Reconnaissance Orbiter to examine the characteristics of 17 meanders from a channel in the Aeolis Dorsa region of Mars. We extracted the topographic signatures from 17 meanders that reveal a characteristic vertically stacked sequence of preserved point bars. These bars increase in elevation by up to 10 m and exhibit incline angles of between one and eight degrees. Each of the meanders is observed to grow vertically while contemporaneously undergoing lateral migration, creating sedimentary architecture not characteristic of fluvial meandering rivers. These landforms are commonly described as inverted channels; however, the preserved architecture differs from other so-called inverted channel topography on Mars, which fail to display such prevalent preserved bar topography. On Earth, vertically stacked deposits are observed in aggradational environments such as in tidally-affected backwater river sections, coastal wetlands, submarine settings, and sediment-rich fluvial systems. Given the pronounced vertical aggradation, and observed in-channel topography, we propose that this channel was fed with an exceptional sediment load – potentially comprised of a high concentration of fine-grained sediment – confined within strong cohesive banks that limited lateral migration and promoted vertical bedform growth. The channel may have also experienced base level controls from a downstream water body. These findings suggest that liquid water must have been persistent over a considerable timescale in Mars’ history.
ESA FRM4DOAS: Towards the launch of the NDACC MAX-DOAS Central Processing Service
Authors: Hendrick Francois , Fayt Caroline , Friedrich Martina M. , Beirle Steffen , Frieẞ Udo , Richter Andreas , Bösch Tim , Kreher Karin , Piters Ankie , Wagner Thomas , Tirpitz Jan-Lukas , Bais Alkis , Prados Roman Cristina , Puentedura Olga , Cede Alexander , Lind Elena , Dehn Angelika , von Bismarck Jonas , Casadio Stefano , Van Roozendael Michel
Published: March 2020

Since it provides vertically-resolved information on atmospheric gases at a horizontal scale approaching the one from nadir backscatter satellite sensors, the ground-based MAX-DOAS technique has been recognized as a valuable source of correlative data for validating space-borne observations of air-quality-related species such as NO2, HCHO, SO2, O3, etc. In this context, the ESA Fiducial Reference Measurements for Ground-Based DOAS Air-Quality Observations (FRM4DOAS) project is aiming at developing a near-real-time (6-24h latency) central processing system for the delivery of harmonized, quality-controlled, and fully traceable data products from MAX-DOAS instruments. The first phase of the project has been dedicated to the development of a prototype version of this processing system for 3 key products (NO2 vertical profiles, total O3 columns, and tropospheric HCHO profiles) and its demonstration at 11 project partners MAX-DOAS stations.

In this presentation we will describe the efforts carried out during the last months to develop the first MAX-DOAS central processing service to be operated within the Network for the Detection of Atmospheric Composition Change (NDACC). The main aspects of the service development will be presented, like the FRM4DOAS prototype algorithm optimisation, operationalisation, and validation, and the establishment of MAX-DOAS NDACC instrument and data retrieval certification procedures, user data policy, datasets DOI, etc. This operational service is expected to be launched in Spring 2020 for a limited number (5-10) of NDACC-certified MAX-DOAS instruments. Corresponding data sets will be stored in the NDACC and ESA EVDC data handling facilities.

This activity and its future upscaling in terms of stations and data products will ensure that MAX-DOAS observations at a FRM quality level will be made available for the validation of present and future satellite missions like the Copernicus atmospheric Sentinels (5p, 4, 5).
Solar Energy and the Water, Energy and Food Nexus: Petrolina-Juazeiro Case Study, Brazil
Authors: Ferraz de Campos Erica , van Oel Pieter , Bueno Pereira Enio
Published: March 2020

Water, energy and food are essential resources for society. Their integrated management, based on synergies and trade-offs, is determinant to attend the demand in long-term. Petrolina and Juazeiro are cities in Brazilian semiarid where coexist: the Sobradinho hydropower (4,214 km² reservoir) and a fruit production center of 223 km², for Brazilian and international markets. Both activities depend on São Francisco River and Sobradinho reservoir. Although the water demand from Sobradinho Reservoir is intense – around 1 billion m³, hydropower generation prevailed as a priority during the dry period 2012-2017. As the National Water Agency (ANA) maintained the reservoir outflow in rates above the water stream inflow, the reservoir was led to its minimum levels. The water scarcity during these years caused conflicts as it reduced hydroelectricity generation while put in risk the fruit production. Since solar irradiation is abundant in this region, solar power plants is figuring as a renewable energy alternative for the national grid. An increasing number of solar projects in this region are being approved in national auctions of electric energy expansion. Moreover, a floating photovoltaic power plant is already being tested in the Sobradinho reservoir. Therefore, the research analyses scenarios of water management if floating solar panels had been adopted in complementarity to hydroelectricity from 1999 and 2018, when very wet and very dry periods occurred. The software Water Evaluation and Planning (WEAP) is used to model the scenarios. Results are represented in water, energy and food safety indicators to identify the strategies of integrated resource management to target SDGs 6, 7 and 12.
Regional Ionosphere VTEC Modelling and Application for Single-Frequency Positioning in the Western Balkans
Authors: Natras Randa , Goss Andreas
Published: March 2020

The ionospheric delay is one of the main error-sources in applications that rely on the Global Navigation Satellite System (GNSS) observations. Dual-frequency receivers allow the elimination of the major part of the ionospheric range error by forming an ionosphere-free linear combination (L3). However, although global models broadcasted by the satellite systems are available, single-frequency mass-market receivers are not able to correct the signal’s delay with sufficient accuracy and precise regional ionosphere models are necessary. Today no regional ionosphere models, based on the national GNSS/GPS infrastructure, are available in the Western Balkans countries.

In this study, an ionosphere vertical total electron content (VTEC) model IONO_WB is derived from dual-frequency GPS observations of Continuously Operating Reference Stations (CORS) belonging to the following positioning networks: ALPBOS and IGEWE (Albania), BIHPOS (Bosnia and Herzegovina), CROPOS (Croatia), MAKPOS (North Macedonia), and SIGNAL (Slovenia). In addition, observations from 8 permanent stations of the EUREF Permanent Network (EPN) in this region are used. The chosen network comprises in total about 70 CORS and EPN stations in the range from about 40⁰ N to 47⁰ N and 13⁰ E to 23⁰ E. The estimation of the ionosphere VTEC model parameters is based on the geometry-free (L4) linear combination of phase (zero-difference) observations. The ionosphere is approximated by a single-layer model at a height of 450 km. TEC modelling is performed by two-dimensional Taylor series expansions in a Sun-fixed reference frame with a degree and order of 2 and a temporal resolution of 1 hour. Corrections for positioning with a single frequency (L1) are estimated and evaluated in positioning application. Data processing, model estimation and positioning evaluation are performed in the Bernese GNSS Software v.5.2

The developed ionosphere IONO_WB model is tested for periods of the solar maximum (March 2014) and the St. Patrick´s geomagnetic storm (March 2015). For validation purposes, the model is compared to Global Ionosphere Maps (GIM) issued by the IGS Associate Analysis Centers (CODE, ESA/ESOC, JPL, gAGE/UPC) and the regional high-resolution VTEC maps from DGFI-TUM realized as multi-scale B-spline representations. The model`s applicability is evaluated with single-frequency positioning, where selected EPN and CORS stations are processed applying the corrections estimated from the regional model IONO_WB. Resulting 3D position errors (RMS) were in most cases at least 20% to 50% lower compared to CODE ionosphere products during high solar activity and severe geomagnetic storm.