bluuebunny/crossref_metadata_2025 huggingface dataset:
A new tool to accurately calculate root reinforcement: the Root Bundle Model software RBM++
Authors: Murgia Ilenia , Cohen Denis , Giadrossich Filippo , Capra Gian Franco , Schwarz Massimiliano
Published: March 2020

The influence of vegetation on the hydro-geomorphological response is widely recognized, and root reinforcement mechanisms are an important component of slope stability models. The calculation of this essential information is very complex because of the multiple interactions in the root-soil system, but also because of several mechanical characteristics that influence the tension and compression behaviour of the root itself.

This contribution has two aims. The first one is to show parameters of root reinforcement effects of Robinia pseudoacacia (L.), a tree commonly used for the mitigation of rainfall-induced landslides at small scale. This species is very widespread because it is able to grow on marginal areas, such as abandoned hillside sites, or on infrastructures, such as road and railway scarps, but its characterization represents a gap in knowledge in the literature. Field pullout tests were performed to collect input data for the quantification of root reinforcement using the Root Bundle Model with Weibull survival function (RBMw, Schwarz et al, 2013). Recent studies have shown how the RBMw is a very efficient model for the evaluation of root reinforcement by considering the heterogeneity of both root mechanical characteristics and their distribution in the soil. However, due to the model complexity and the need for information difficult to obtain, other simpler but less accurate approaches, such as the Wu model, have been preferred. 

For this reason, the second aim of the work is to present a new tool written in C++, and called RBM++, easy to use that enables anyone, from Universities to private companies, to quantify the effect of roots on slope stability. RBM++ allows the calculation of root reinforcement using two different methods: the first one by entering own data of the mechanical parameters of the roots, estimated beforehand with pullout tests in the field, and the root distribution in the soil; the second one by selecting the tree species and the data related to the spatial root distribution. For the first method, it is necessary to use a pullout machine to obtain the data. Because this instrument is not commonly available the model has the option to use default parameters for nine tree species based on values found in the literature. 

Output from RBM++ comes in tabular format and with a plot that shows, via the graphical user interface, the spatial distribution of forces as a function of the distance from the tree trunk and size of the tree.   

RBM++ makes it easier to share and exchange knowledge related to root reinforcement. Therefore, it will allow the realization of a database containing standard data on root mechanical behavior of tree species commonly used for shallow landslide mitigation.
Non-adiabatic interaction of ions with solar wind discontinuities
Authors: Vinogradov Alexander , Artemyev Anton , Vasko Ivan , Vasiliev Alexei , Petrukovich Anatoly
Published: March 2020

According to Helios, Ulysses, New Horizons measurements at a wide range of distances from the Sun, radial evolution of solar wind ion temperature significantly deviates from the adiabatic expansion model:  additional heating of the solar wind plasma is required to describe observational data. Solution of the solar wind heating problem is extremely important both for understanding the structure of the heliosphere and for adequately describing the atmospheres of distant stars. Solar wind magnetic field is turbulent and this turbulence is dominated by numerous small-scale high-amplitude coherent structures – such as quasi-1D discontinuities. Modern theoretical models predict that quasi-1D discontinuities can play important role in solar wind heating. We collected the statistics of MMS observations of thin quasi-1D discontinuities in the solar wind to reveal their characteristics. Analyzing observational data, we construct the discontinuity model and use it to consider non-adiabatic interaction of ions with solar wind discontinuities. We mainly focus on discontinuity roles in solar wind ion scattering and thermalization. This presentation shows how discontinuity configuration affects the scattering rates.
Seismic diffusivity: The influence of fracture networks on the patterns of induced seismicity.
Authors: Haagenson Ryan , Rajaram Harihar
Published: March 2020

It has been long understood that the injection of fluids into the subsurface, a common practice in several industries, often leads to seismic activity by altering the fluid pressures and stress states acting along fault structures. In some cases, this puts the people and infrastructure located nearby at considerable risk. The effective mitigation of this potential hazard relies heavily on understanding the physical mechanisms controlling the behavior of injection-induced seismicity. Here, we aim to better understand the spatiotemporal patterns of the seismicity through the concept of triggering fronts (i.e. the propagating front where the onset of seismicity occurs). Previously, triggering fronts have been studied mostly in the context of homogenous porous media. Here, field scale simulations of fluid injection into fractured rock are modeled as linear, uncoupled fluid flow. While injection-induced seismicity is certainly affected by poroelastic stressing and nonlinear hydraulic parameters of the rock, the focus of this study is to understand the impact of a discrete fracture network on patterns of seismicity. Therefore, poroelastic and nonlinear effects are ignored. Results indicate that the pathways of high permeability within the fracture network greatly influence the migration of the triggering front. While the triggering front clearly follows a diffusive process as expected, the corresponding diffusivity is found to be distinct from the effective hydraulic diffusivity of the domain. We, therefore, call this diffusivity the seismic diffusivity of the fractured rock. Understanding seismic diffusivity may help us better interpret datasets of injection-induced seismicity and potentially forecast the patterns of injection-induced seismicity in well-characterized formations.
Reconciling global land model estimates and country reporting of anthropogenic land CO2 sources and sinks with the CMIP6 LUMIP NOAA/GFDL LM4.1 simulations
Authors: Shevliakova Elena , Malyshev Sergey , Houghton Richard , Verchot Louis
Published: March 2020

Global land models, which often served as components Earth system models, and national GHG inventories rely on different methods and produce different estimates of anthropogenic CO2 emissions and uptakes from land use land cover changes throughout historical period. For example, for 2005 -2014, the sum of the national GHG inventories net emission estimates is 0.1 ± 1.0 GtCO2 yr–1 while the bookkeeping models is 5.2 ± 2.6 GtCO2 yr–1 (IPCC SPM 2019).  Previous estimates with the 16 global stand-alone land models produced an estimate of the net land sink of 11.2 ± 2.6 GtCO2 yr–1 during 2007– 2016 for the natural response of land to human-induced environmental changes such as increasing atmospheric CO2 concentration, nitrogen deposition, and climate change (IPCC SPM 2019).  However, these 16 models do not provide separate estimates for the managed and unmanaged lands. 

 

Here we use results from simulations with the NOAA/GFDL new land model LM4.1 from the CMIP6 Land Use Model Inercomparison Project (LUMIP) to demonstrate how to reconcile the discrepancy between the inventories and land models estimates of the anthropogenic CO2 land emissions by using bookkeeping accounting approach applied to the model results.  In addition, we separate estimates of land fluxes on managed and unmanaged lands. Key features of this model include advanced, second generation dynamic vegetation representation and canopy competition, fire, and land use representation driven by full set of gross transitions from the CMIP6 land use scenarios.  We demonstrate how bookkeeping accounting combined with the LUMIP experiments can enhance understanding of land sector net emission estimates and their applications.
Unraveling Zr/Hf fractionation: Hydrothermal zirconium and hafnium fluoride complexation up to 400°C
Authors: Loges Anselm , Louvel Marion , Wilke Max , Klemme Sthephan , John Timm , Hasenstab-Riedel Sebastian
Published: March 2020

High field strength elements (HFSE) such as Zr and Hf are relatively insoluble in most natural hydrothermal solutions and consequently immobile in most geological systems. However, fluoride forms stable aqueous complexes with many HFSE ions, including Zr4+ and Hf4+, and is thus a potent mobilizer of these elements. Due to their identical charge and similar ionic radius (590 pm and 580 pm, respectively), Zr and Hf behave almost identically in geological system and are therefore referred to as geochemical twins. Fluoride complexation in hydrothermal environments is one of few processes in the Earth's crust that can effectively fractionate them from one another. This fact can be used to trace past fluoride activity in fossil hydrothermal systems by investigating Zr/Hf ratios, if fluoride complexation of Zr and Hf is sufficiently well understood. Mobility of metals as complexes is controlled by two distinct but related mechanisms: Formation of the complex itself and solvation of that complex in the solvent. Poly(hydrogen-fluoride) bridging of fluoride complexes to the surrounding aqueous solvent is crucial to the understanding of the solvation and therefore the mobility of fluoride complexes.

We report geometries of Zr and Hf fluoride complexes up to 400°C, determined by extended X-Ray absorption fine structure (EXAFS) in a hydrothermal autoclave. Existing data sets on the stability of those complexes at lower temperatures are extended to 400°C. Our data show strong temperature dependence of the complex stability for both metals. However, the effect of temperature is not equally strong for Zr and Hf. Fractionation of the twin pair is thus a function of temperature as well as fluoride activity.
Re-imagining urban coasts: a socio-geomorphology lens to enhance life in an era of extremes
Authors: Naylor Larissa , Hansom Jim , Mitchell Douglas , Fitton James , Muir Freya , Hurst Martin , Rennie Alastair
Published: March 2020

Geomorphology has much to contribute to the understanding of how geomorphic landscapes have responded to climatological extremes and will likely respond in the future. These contributions can be in terms of systems dynamics and their past, present and likely future responses to sudden events, tipping points or more gradual changes to natural landforms and anthropogenic structures. However, equally importantly, geomorphic contributions also include making proactive resilience and climate change adaptation decisions in order to create physical space for geomorphic systems to respond more naturally and dynamically to extremes – now or in the near (100 year) future. The choices society makes in the present – such as planning, infrastructure and engineering decisions – have a strong bearing on the physical space left to allow natural landforms to adjust to extreme events while minimizing social and economic impacts. This creates a new frontier for geomorphology science at the social, political and policy interface.  Interesting questions arise in this space, such as: How much do we expect a geomorphic system to respond dynamically to extreme forcing? i.e. How much physical space do we [planners] need for the system to respond to an extreme event? Should society see storms as catalysts for proactive adaptation? How much (physical space, i.e. geomorphic accommodation space) can we allow when realigning road or rail inland to reduce risk in future storm events? How do complex physical geomorphic systems interact with complex urban systems? Can we work with artists, landscape architects, geo-spatial, urban and social scientists to create transformative, systems-based adaptation scenarios to allow us to better live in an era of extremes? Geomorphologists are usefully contributing to improving the resilience and/or limiting deterioration or habitat loss (e.g. habitat squeeze due to sea level rise) in urban ecosystems and anthropogenic structures.  This includes geomorphic contributions to nature-based solutions, green infrastructure and the resilience of traditional engineering to extreme events.  This paper highlights some of the opportunities we have to influence and shape our future resilience to extreme events – in the present day – through interdisciplinary research and socio-geomorphology practice. We need to create windows of opportunity now for more dynamic and resilient geomorphic futures.  
Cenozoic climate evolution revealed by clumped isotope thermometry
Authors: Ziegler Martin
Published: March 2020

When it comes to paleoclimate data-model integration, temperature is arguably the most important parameter. Although a range of temperature proxies has been developed over the decades, many of the available methods suffer from large calibration uncertainties, in particular when applied on deep-time intervals. Clumped isotope thermometry is based on thermodynamic principles and therefore can provide accurate temperature constraints for the deeper geological record. Recent analytical developments allow now the analysis of relatively small sample sizes and the application in paleoceanogaphic studies becomes more feasible. I will present new clumped isotope based temperature estimates for the Atlantic deep-sea across the Cenozoic. I will also show that the analysis of small samples now allows us to even resolve seasonal sea surface temperature estimates from high-resolution archives. Deep-sea temperatures as well as seasonally resolved surface temperature estimates are particularly useful for data-model comparison.
Determination the influence of liming with oilshale ashes to the changes of water extractable plant nutrients in acidic soils
Authors: Ilves Mihkel , Köster Tiina , Krebstein Kadri , Tõnutare Tõnu
Published: March 2020

The acidification process influences mostly soils used agriculturally. It causes yield decrease and loss of plant nutrients from soil via leaching and also rise in concentration of undesibrable, harmful for plant roots ions ( Al3+) in soil solution.

To overcome the negative effects of acidification to agricultural plant production, liming of agriculturally managed soils is widely in use. 40% of agriculturally used lands in Estonia needs periodic liming and approximately 130 000 tons of liming material will be needed for neutralizing acidic soils every year.  Typically different naturally occouring carbonatic materials , as limestone and dolomite, is used for this purpose.  In Estonia more than 9 million tons of ash has been produced as waste byproduct in Estonian power plants every year. Only 1,9% of this byproduct has been reused in building materials industry and agriculture. The amounts of oilshale ash used as liming material by farmers is increasing from year to year.  

The oilshale fly ash is higly alkaline material with high content of Ca (20 – 33% ), K ( 2,6 – 10%), Mg (2 – 4%) and several microlelement (Zn, Cu, Mo, Mn). Due to modernization of powerplants the new burning technology (CFB) was introduced. Therefore the the fly ash with new chemical and physical properties appeared on the market of liming agents for farmers.

The aim of the research was to investigate the change of water soluble plant nutrient  (P, K, Mg, Ca) content in acidic soils as a result of liming with oilshale fly ash.  Experiment was conducted as a pot experiment  with five different soils and three fly ashes and two types of granulated ashes and powdered limestone.  The influence of soil organic carbon, soil acidity, texture, to the water soluble  nutrient gradient in soil was investigated. 

The differences between oilshale ashes to the changes in nutrient gradient was found. The Nutrient gradient depends from oilshale ash as well from soil properties.   
Analytics Optimized Geoscience Data Store with STARE-based Packaging
Authors: Kuo Kwo-Sen , Rilee Michael
Published: March 2020

The only effective strategy to address the volume challenge of Big Data is “parallel processing”, e.g. employing a cluster of computers (nodes), in which a large volume of data is partitioned and distributed to the cluster nodes. Each of the cluster nodes processes a small portion of the whole volume. The nodes, working in tandem, can therefore collectively process the entire volume within a much-reduced period of time. In the presence of data variety, however, it is no longer as straightforward, because naïve partition and distribution of diverse geo-datasets (packaged with existing practice) inevitably results in misalignment of data for the analysis. Expensive cross-node communication, which is also a form of data movement, thus becomes necessary to bring the data in alignment first before analysis may commence.

 

Geoscience analysis predominantly requires spatiotemporal alignment of diverse data. For example, we often need to compare observations acquired by different means & platforms and compare model output with observations. Such comparisons are meaningful only if data values for the same space and time are compared. With the existing practice of packaging data using the conventional array data structure, it is nearly impossible to spatiotemporally align diverse data. Because, while array indices are generally used for partition and distribution, for different datasets (even data granules) the same indices most-often-than-not refer to different spatiotemporal neighborhoods. Partition and distribution using conventional array indices thus often results in data of the same spatiotemporal neighborhoods (from different datasets) reside on different nodes. Comparison thus cannot be performed until they are brought together to the same node.

 

Therefore, we need indices that tie directly and consistently to spatiotemporal neighborhoods to be used for partition and distribution. SpatioTemporal Adaptive-Resolution Encoding (STARE) provides exactly such indices, which can replace floating-point encoding of longitude-latitude and time as a more analytics-optimized alternative. Moreover, data packaging can base on STARE indices. Due to its hierarchical nature, geo-spatiotemporal data packaged based on STARE hierarchy offers essentially a reusable partition for distribution adaptable to various computing-and-storage architectures, through which spatiotemporal alignment of geo-data from diverse sources can be readily and scalably achieved to optimize parallel analytic operations.
Changes in the timing and length of the fire season in Spain
Authors: Urbieta Itziar R. , Arellano Gonzalo , Moreno José M.
Published: March 2020

Fire activity has decreased in the last decades in Spain, as a whole and in most regions. However, little is known about the changes in the fire season peak, timing, and length. Here we studied the temporal variation in the fire season since the 1970’s for different Spanish regions. We analyzed weekly time series of annually burned area by fitting GAMs (Generalized Additive Models) models in R. Area burned was log transformed and smoothing P-splines were fit to study weekly seasonality. GAMS allowed us to model spring, summer, and autumn fire seasons. Changes in the sign of the smoothing parameter determined the timing (onset/end dates) of each fire season, while the maximum value of the parameter established the peak of the fire season. We applied trend analysis to study inter-annual variation in fire season timing, length, and amplitude. We found temporal and spatial differences in the fire season across regions. In the northern Atlantic regions, models performed better, and captured a bimodal fire season (spring-summer). Nonetheless, the bimodal fire-season structure is no longer distinguishable in recent years, since both are increasing in duration. In the Mediterranean regions, larger peaks of burned areas occur in shorter time spans. The amplitude and duration of the summer season is decreasing, probably due to the increase in fire suppression during the summer. The summer season is starting earlier, while, in general, no trend was found for the end of the season. Furthermore, spring fire peaks in Mediterranean regions are becoming more frequent, suggesting that more attention should be paid to these out-of-season conditions.
Numerical Dispersion of Bed Load in a 1D Model Mimics Physical Flume Results
Authors: Dahl Travis , Gibson Stanford , Floyd Ian , Sanchez Alejandro
Published: March 2020

The longitudinal dispersion of bed load particles as they move downstream in a river is relevant both to cases of polluted sediment and pulses of sediment released during reservoir flushing events or dam removals.  To quantify the rate of bed-load dispersion, researchers with the U.S. Army Corps of Engineers conducted a series of flume experiments using successive additions of different-colored sediment in a 22m x 0.9m, upstream-fed, tilting flume at the U.S. Engineer Research and Development Center's (ERDC) Coastal and Hydraulics Laboratory.  Here we show that longitudinal bed-load dispersion can be accurately modeled in a one-dimensional sediment transport model (HEC-RAS) that does not explicitly simulate dispersion.  We accomplished this by adjusting the active layer thickness and the bed-load depositional exchange increment.  The bed-load depositional exchange increment sets the ratio of active layer vs. bed-load material that are mixed into the bed during deposition.  The optimal parameters varied between the flume experiments, but smaller active layer thicknesses generally performed better. 
Seismic activity along a Cretaceous magmatic intrusion in Monchique, SW Iberia
Authors: Soares Analdyne , Custódio Susana , Neres Marta , Vales Dina , Matias Luís
Published: March 2020

Iberia, located at the southwestern end of Europe, displays a complex pattern of seismic activity, with most known active faults slipping at low rates (< 1 mm/yr). However, the seismic activity is remarkable, with numerous earthquakes in the historical record proving destructive. The earthquake cluster in mainland Portugal that has a highest rate of seismic activity is very localized (small spatial extent), extends vertically from 5 to 20 km depth and lays on the Monchique late Cretaceous magmatic intrusion, in SW Portugal. This magmatic intrusion forms strong rheological contrast between the intruded magmatic rocks and surrounding Paleozoic rocks. Furthermore, it is the locus of abundant natural water springs. Several pertinent questions remain to be answered concerning earthquakes in Monchique: Are earthquakes in Monchique simply a response to tectonic stresses (given the proximity of Monchique to the EU-AF plate boundary), with the localization of brittle failure in the region facilitated by the rheological contrast between the Cretaceous intrusion and surrounding Paleozoic rocks? Do fluids play a role in facilitating slip in existing fractures? Or, conversely, is the circulation of fluids facilitated by the faulting that results from the rheological contrasts? Are there hazardous faults in Monchique? In this presentation, we re-analyze in detail the seismic data recorded by the regional permanent seismic network, in order to better understand the relationship between seismic activity and igneous intrusion. In particular, we re-locate earthquakes using NonLinLoc and PRISM3D, a 3D velocity model for the region. At a subsequent step, we re-locate earthquakes using HypoDD. We also perform a clustering analysis based on waveform similarity and compute focal mechanisms for the region. The results show that earthquakes align along two main directions, E-W and NNE-SSW, coinciding with surface features of the magmatic intrusion. Focal mechanisms indicate dominantly strike-slip faulting, with the possible fault planes coinciding with the favored directions of earthquake lineations. We investigate the spatio-temporal evolution of seismicity and address possible forcing mechanisms, including tidal forcing.

 

 

The author would like to acknowledge the financial support  FCT through project UIDB/50019/2020 – IDL and PTDC/GEO-FIQ/2590/2014 - SPIDER.
Abrupt shrinking of solar corona in late 1990s and related changes in solar magnetic structure
Authors: Mursula Kalevi , Virtanen Ilpo , Koskela Jennimari , Tähtinen Ismo
Published: March 2020

Several studies have noted on changes in the properties of sunspots, and in the mutual relations between various global parameters of solar magnetic activity (e.g. UV/EUV irradiance, radio and IR emissions, TSI/SSI), as well as between solar and ionospheric parameters since the onset of solar cycle 23. These changes have been suggested to be related to the overall reduction of solar activity at the aftermath of the decline of the Grand modern maximum of solar activity that prevailed during most of the 20th century. We have recently derived the longest record of coronal magnetic field intensities since 1968 using Mount Wilson Observatory and Wilcox Solar Observatory observations of the photospheric magnetic field and the PFSS model, and compared it with the heliospheric magnetic field observed at the Earth. We found that the time evolution of the coronal magnetic field during the last 50 years agrees with the heliospheric magnetic field only if the effective coronal size, the distance of the coronal source surface of the heliospheric magnetic field, is allowed to change in time. We calculated the optimum distance for each solar rotation and found that it experienced an abrupt decrease in the late 1990s. The effective volume of the solar corona shrunk to less than one half of its previous value during a short period of only a few years. This shrinking was related with a systematic change in the structure of the coronal magnetic field during the same time interval. We review these dramatic changes in the solar corona and discuss their possible connection to the changes in the different solar activity parameters and the reduction of the overall solar activity.
Small but essential in hydrogeochemical cycles: headwater mountain catchments
Authors: Le Roux Gaël , Haver Marilen , Rosset Thomas , Schmeller Dirk , Gandois Laure , Allen Deonie , Binet Stéphane , Simonneau Anaelle , Grusson Youen , Camboulives Thierry , Sauvage Sabine , Galop Didier , Gascoin Simon , Sánchez Pérez José Miguel
Published: March 2020

Despite their small size, headwater catchments of European mountains are essential because they provide many ecosystem services (water quality, energy, tourism, ecological niches).

Based on the hydrological monitoring of a mountain catchment in the central Pyrenees and the extreme conditions encountered in the past and expected in the future, we present scenarios for the evolution of hydrological regimes that will potentially impact the socio-ecological services by high mountain mires, ponds and lakes. In particular, in view of the exacerbated climate change in the high mountains, the shortening of snow season will potentially impact the ecosystem services by the ponds, modifying the minimum water level and/or ecological flow in late spring and early summer. For example, these ponds play an essential role as ecological refuges compared to larger lakes, which are subject to invasions by non-native organisms. Peat pools also play an essential role in the cycling of chemical elements, including carbon. Their modification, their increased intermittency due to more frequent and intense climatic variability will deeply modify, for example, the export of dissolved organic carbon from peatlands.

While it is difficult to accurately predict the future of mountain watersheds, our study aims to identify the key factors for their current roles in biodiversity, water sustainability and in ecological services as well as to determine their future adaptability to other human pressures such as mini-hydroelectric power plants.
An open water mechanism of seawater intrusion in the coastal Yucatan aquifer
Authors: Salles Paulo , Pacheco-Castro Roger , Canul-Macario Cesar , López José
Published: March 2020

The Yucatan state, Mexico, encloses a large karstic aquifer, which is confined near the coast. There are places where this confinement is fractured creating springs that discharge to wetlands or shallow lagoons, which are important because of the freshwater ecosystems that develop around them (locally known as Petenes), and because they provide a thermohaline equilibrium in these systems. Previous studies reported that during spring low tide, the spring becomes a sink, reversing the flow in the Peten channel connecting the lagoon to the spring. Potentially, this inversion of the flow can cause the intrusion of brackish – and sometimes hypersaline - water from the lagoon into the aquifer, which can also have ecological implications. The flow reversal was observed in two sampling campaigns and it occurred a total of 16 times. In the last sampling campaign, it was confirmed that the spring becomes a sink, with measured water velocities of about 0.37 m/s at the channel end close to the spring. Preliminary results suggest that the flow reversal is controlled by the discharge from the aquifer, the confinement of the aquifer, the geometry of the lagoon and the inlet channel, as well as the sea tides. A simple 1D analytical solution was used to explain this phenomenon, which describes the hydrodynamic interaction between the lagoon and the aquifer by solving the heat equation, which can be used to simulate flow in both systems, a confined aquifer and a highly frictional lagoon. Therefore, the same solution was used to simulate the gradients observed between the confined aquifer and the lagoon. The solution was implemented as a Python library using Fourier series, and has the advantage that it can be used with more general boundary conditions and finite length systems. Finally, we present coefficients that can be used to determine under which conditions the flow reverses at the lagoon.
Biochar reduces total greenhouse gas emissions from oilseed rape cultivation, mainly due to C sequestration quantified by the concept of avoided atmospheric CO2 load – a theoretical life cycle assessment study.
Authors: Thers Henrik , Njakou Djomo Sylvestre , Elsgaard Lars , Trydeman Knudsen Marie
Published: March 2020

Biochar is related to multiple greenhouse gas (GHG) mitigation potentials, namely nitrous oxide (N2O) mitigation, carbon (C) sequestration and the possible green electricity produced in the pyrolysis process. Whereas the mechanisms behind potential N2O mitigation effects of biochar are still unclear, the mechanisms behind C sequestration is agreed to be caused by C compound conversion towards aromatic structures in the biochar C as a consequence of the heating treatment in the pyrolysis process. The specific recalcitrance of the biochar is, however, difficult to estimate. The possible electricity production from the syn-gas and bio-oil pyrolysis products depends on the feedstock and process temperature, and can contribute considerably to total system GHG mitigation. However, the multiple effects on GHG balances of biochar and pyrolysis represent a complexity, which may best be analysed by a life cycle assessment (LCA) approach. In this study, the average Danish oilseed rape cultivation was set as the reference scenario in an LCA of cultivation related GHG emissions. The reference was compared with two scenarios with theoretical inclusion of pyrolysis and biochar, meaning that the oilseed straw residue was transported to a pyrolysis plant and the biochar was returned to the field in a corresponding amount (ca. 1 Mg ha-1). Transportation, additional field operations, N2O mitigation, electricity production and C sequestration was included, and the latter was calculated by using the concept of avoided atmospheric CO2 load. The latter approach resulted in larger mitigation effects than derived from calculations of just the remaining C in soil. In total, GHG emissions were reduced by 73 to 83% in the two biochar scenarios as compared with the reference scenario, mainly due to increased C sequestration. The study suggests that even low application rates and rather conservative biochar C recalcitrance estimates lead to considerably reductions in GHG emissions from oilseed rape and expectedly other crops.
Can we predict Dry Air Intrusions using an Artificial Neural Network?
Authors: Nahum Stav , Raveh-Rubin Shira , Shlomi Jonathan , Silverman Vered
Published: March 2020

Dry-air intrusions (DIs) descending from the upper troposphere toward the surface are often associated with abrupt modification of the atmospheric boundary layer,air-sea interface, and high impact weather events. Understanding the triggering mechanism of DIs is important to predict the likelihood of their occurrence in both weather forecasts and future climate projections.

The current identification method of DIs is based on a systematic costly Lagrangian method that requires high vertical resolution of the wind field at sub-daily intervals. Therefore, the accurate prediction of surface weather conditions is potentially limited. Moreover, large case to case variability of these events makes it challenging to compose an objective algorithm for predicting the timing and location of their initiation.    

Here we test the ability of deep neural networks, originally designed for computer vision purposes, to identify the DI phenomenon based on instantaneous 2-dimensional maps of commonly available atmospheric parameters. Our trained neural network is able to successfully predict DI origins using three instantaneous 2-D maps of geopotential heights.

Our results demonstrate how machine learning can be used to overcome the limitations of the traditional identification method, introducing the possibility to evaluate and quantify the occurrence of DIs instantaneously, avoiding costly computations and the need for high resolution data sets which are not available for most atmospheric data sets. In particular, for the first time, it is possible to predict the occurrence of DI events up to two days before the actual descent is complete.
Velocity fields in Northern Caspian near Jayik (Ural) river delta
Authors: Rezvov Vadim , Zavialov Peter , Krinitskiy Mikhail
Published: March 2020

The Caspian Sea is the largest inland water body on the Earth and a unique object for analysis. It is of great importance for the socioeconomic development of bordering countries. Unique fish resources and oil and gas fields are projected to provide a significant source of food and economic prosperity to the Caspian region, as well as energy to many parts of the world. National and transnational oil and gas corporations are involved in the utilization of the commercially attractive Caspian natural resources. The Caspian Sea has been influenced by climate change and anthropogenic disturbance during recent decades, yet the scientific understanding of this water body remains poor. Climatic variability of water circulation in the Caspian Sea remains unclear. Traditionally, currents in the Caspian Sea have been investigated by numerical methods. Instrumental observations of the currents in the Caspian Sea are mostly carried out in the shelf zone. Available data cover very short periods and reflect variability only in synoptic and higher frequency of the sea dynamics. In this work, water velocity data based on SeaHorse equipment is under consideration. Three stations were in northern Caspian, area adjacent to Jayik (Ural) River delta. In both cases, the instruments were deployed in 2016 and 2017 at the point 46.782N, 51.384E, depth about 3 m. In this work, we will present the preliminary results of our study of the field observations we gathered in these points. We also present the analysis of the potential drivers for the spatial and temporal patterns of the measured currents velocity.
Water system recovery after two consecutive years of extreme droughts
Authors: Pouwels Janneke , de Louw Perry , Hendriks Dimmie , Hunink Joachim
Published: March 2020

In large parts of Europe, the year 2018 is known as an extremely dry year. In the Netherlands this 2018 drought caused over 1 billion euros of economic damage to different sectors like agriculture, nature, industry, shipping, infrastructure and buildings. A large part of economic damage was due to extreme low groundwater levels and large soil moisture deficits. Many streams stopped flowing since groundwater levels were too low to feed the streams. The extreme low rainfall amount, in combination with above average high potential evaporation rates, caused a precipitation deficit of 300 mm in the growing season, which is normally less than 100 mm. In 2019, the year after, the spatial variability of precipitation in the Netherlands was high with only a precipitation deficit in the growing season of a few tens of millimeters in the low-lying western part of the Netherlands. However, in the higher sandy areas in the south and east part of the Netherlands, the precipitation deficit was again extreme and more than 240 mm. For the higher sandy areas this was the second dry year in a row and the question arose what the effect of two consecutive dry years on the water system was and how fast it may recover.

This question has been analyzed by applying an integrated nationwide groundwater and surface water model (De Lange et al., 2014). The model results showed that for the higher sandy areas, groundwater levels and stream discharges were even lower in the second than in the first dry year. In addition, the recovery period of the groundwater system after two extremely dry years was examined by simulating ten "normal" years with average precipitation and evaporation patterns following the two extremely dry years. The model results showed a large spatial variation in groundwater level recovery.  In the first recovery year groundwater levels increased for most of the area, except for the higher-lying sandy areas lacking any surface waters (ditches and streams), like the largest Dutch forest area, the Veluwe. In these slow-responding regional recharge areas, groundwater levels are still dropping. For the central part of the Veluwe, this dropping continues until the seventh recovery year.  The model results showed that two consecutive dry years have a large impact on the water system, and that full recovery of groundwater levels and stream discharges may take 2 to 4 years in most of the sandy areas, yet the recovery of the highest parts may take up to 7 to 8 years.

 

De Lange, W.J., Prinsen, G.F., Hoogewoud, J.C., Veldhuizen, A.A., Verkaik, J., Oude Essink, G.H.P., Van Walsum, P.E.V., Delsman, J.R., Hunink, J.C., Massop, H.Th.L., Kroon T. (2014). An operational, multi-scale, multi-model system for consensus-based, integrated water management and policy analysis: The Netherlands Hydrological Instrument. Accepted for publication in Environmental Modelling & Software
Drivers of vegetation activity during European summers: A causal inference approach applied to solar-induced fluorescence observations
Authors: Martens Brecht , Pagán Brianna , Maes Wouter , Gentine Pierre , Miralles Diego
Published: March 2020

 Summer weather in Europe has become more extreme in recent years. Several studies have focused on unraveling the influence that this extreme weather may have on ecosystem dynamics. However, traditional optical indices characterise the state of vegetation in terms of greenness or structure, but fail to capture short term impacts on vegetation activity caused by water or heat stress. Being a byproduct of photosynthesis, solar induced fluorescence (SIF) represents an exception, since its dynamics may reflect an integral of the environmental stressors that have immediate influence on ecosystem water, energy and carbon exchanges during droughts or heatwaves. Spaceborne datasets of SIF have not only been used to monitor crop photosynthetic activity and GPP at global scales, but also as a proxy of transpiration dynamics, or even biogenic volatile organic compound emissions. Additionally, numerous case studies have indicated the potential of using SIF for early drought detection and monitoring of ecosystem impacts. 

However, as with most earth science applications, the majority of previous studies rely on correlations or linear regressions to establish these cause–effect relationships, which implies that the actual drivers of drought and periods of vegetation stress remain largely unresolved.

Here we examine the underlying causality and interactions between vegetation activity (represented by changes in SIF) and potential environmental drivers of vegetation stress over Europe during the summer months. Using satellite observations of  photosynthetically active radiation (PAR) and the fraction of absorbed PAR (fPAR), the SIF signal is decomposed into the component that relates to fPAR and the component that relates to the fluorescence yield, which represent different physical and biochemical responses to vegetation stress. Using recently developed methods for causal inference applications in Earth science (https://causeme.uv.es/), the dynamics of SIF and its deconstructed components are evaluated against satellite observations of soil moisture, vapor pressure deficit and temperatures. Common causal relationships and dynamics are observed when grouping regions by aridity index and fractions of vegetation cover. Results help establish direct and indirect links of potential drivers of vegetation activity during periods of heat and water stress.
Estimating load of emerging pollutants originating from urban surfaces
Authors: Kardos Máté Krisztián , Budai Péter , Clement Adrienne , Knolmár Marcell
Published: March 2020

Besides agricultural land, settlement areas are among the primary sources for diffuse contamination of surface waters. Both organic and inorganic compounds originate from wash-off of road and roof surfaces, industrial areas as well as illegal wastewater discharge.

In an 18-month measurement campaign, flow triggered composite water samples were gathered using an automatic sampler, partly in small urban creeks draining settlement areas, partly from storm water channels in 7 mid-sized to large towns (30,000 to 1,800,000 inhabitants) in Hungary. Besides the automatic samples, characteristic runoff events were manually grab-sampled, leading to a time series of the contaminants. Both types of samples were analyzed for the total amount of nutrients (N and P), heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Zn) and 16 PAH forms.

In this contribution, the first results of the sample analyses are presented. The concentration of the measured contaminants is significantly higher during runoff events than in dry periods and can be linked to the amount of road and roof areas on the catchment. Flow triggered composite water samples are efficient in estimating total event load amounts, which were calculated for the pilot catchment areas.
Satellite-based Sun-Induced Chlorophyll Fluorescence in the Greater Alpine Space: Spatial Patterns and Relationship to Gross Primary Productivity
Authors: Gomarasca Ulisse , Duveiller Gregory , Cescatti Alessandro , Wohlfahrt Georg
Published: March 2020

Accurate estimation of terrestrial gross primary productivity is essential for the development of credible future carbon cycle and climate simulations. Current remote sensing techniques allow retrieval of sun-induced chlorophyll fluorescence (SIF) as a valid proxy for GPP, but low resolution, sparse coverage, or resolution mismatches between the different satellite sensors hinder our ability to effectively link SIF to many environmental variables at fine scales. In order to better characterize heterogeneous landscapes, several attempts to downscale SIF products to higher resolutions have been made. We investigate the ability of the downscaled GOME-2 product developed by Duveiller et al. (2019), to capture the differences in spatiotemporal dynamics over the Greater Alpine Space. We analyse SIF in connection to land cover and elevation, and calculate land phenology metrics based on seasonal SIF time series. Ground-based GPP validation suggests biome-specific SIF-GPP relationships, but the comparison was hindered by the resolution mismatch of the data. Moreover, missing data are present at high elevations, diminishing the suitability of current SIF products to analyse cloud-prone mountainous areas. Important insights into spatial patterns and seasonal trends could be inferred at forest and other large-area land cover types, typical of mid elevations in the Alps, but many anthropogenic habitats at low elevations, as well as high elevation grasslands and other small-scale heterogeneous environments could not be thoroughly investigated and are likely to be underrepresented or prone to biases. Similar downscaling procedures might be applied at finer scales to e.g. TROPOMI products, or alternative advanced remote sensing SIF techniques and instruments might be needed in order to enable detailed and systematic evaluations of the Alpine region or similar highly heterogenous landscapes, before a process-oriented monitoring and unbiased implementation into climate models may be performed.
Morphodynamic types of postglacial cliffs of the Southern Baltic
Authors: Kostrzewski Andrzej , Winowski Marcin , Zwoliński Zbigniew
Published: March 2020

The contemporary morphogenetic system of the South Baltic Sea is clearly changing, both in the annual and long-term weather cycle. Morphogenetic seasons are subject to change, both in terms of duration and types of morphogenetic processes and related forms of relief. The duration of the late-autumn and early-spring season is clearly increasing, which is associated with the occurring climate change and related hydrometeorological conditions. All this means that the morphodynamic types of the South Baltic coast are subject to change, the nature of which is conditioned by geological structure, relief, land cover and, hydrometeorological conditions. Undoubted individuality of the geo-diversity of the South Baltic coast in Poland are postglacial cliff coasts (50 km long).

Systematic geomorphological mapping of cliff coasts carried out since 1975 which have recently been supported by GIS methods, allow the recognition of cliff coast development mechanisms, emerging landforms and associated morphodynamic types of the South Baltic coast.

Based on repetitive geomorphological mappings, the following morphodynamic types of the South Baltic cliffs can be distinguished: landslide-type, rock fall-type, talus-type, slump-type and flow-type.

The basis for the typology of morphodynamic types of cliff coasts was the dominant types of relief forms, including lithology, exposure, land cover and hydrometeorological conditions. It can be unequivocally assumed that the morphodynamic types of the cliff coast is a good indicator feature of monitored morphogenetic systems and their space-time variability.

The effect of the observed climate change is the increasing frequency of storm surges that initiate denudation processes of an extreme nature. Another consequence of the observed climate changes is the increasing variability of morphodynamic types of the South Baltic cliff coast in the analyzed morphogenetic seasons with a greater share of landslide and rock fall-types.