bluuebunny/crossref_metadata_2025 huggingface dataset:
Turbulent dynamics and ice-shelf basal melt rates from large-eddy simulations
Authors: Begeman Carolyn Branecky , Asay-Davis Xylar , Van Roekel Luke
Published: March 2021

Large-eddy simulations are used to investigate boundary layer turbulence and its control on ice-shelf basal melt rates in Antarctic settings. We present simulations at relatively low thermal driving and low ice-shelf basal slopes, resulting in simulated melt rates from 10s cm/yr to several m/yr. Our results are broadly consistent with the linear relationships between far-field thermal driving and melt rate and between ice-shelf slope and melt rate reported by previous studies. The simulated thermal exchange coefficient is lower than recommended values; thermal exchange becomes less efficient as stratification increases.  In our simulations, shear production of turbulent kinetic energy outweighs buoyant production, as found below Larsen C Ice Shelf through recent microstructure measurements. We also find that turbulent intensity and melt rate vary significantly with the orientation between the ice-shelf slope and the far-field flow, even at low ice-shelf slopes. Our results suggest that numerical ocean models employing the standard ice-shelf melt parameterization will underestimate slope effects on ice-shelf melt rates even if they capture the mean buoyancy effects on boundary layer flow. The proposed slope effects would modify feedbacks between ocean circulation and ice-shelf geometry and tidal variability in ice-shelf melt rates.
Potential vorticity dynamics of life cycles of blocked weather regimes in the Euro-Atlantic region: A diagnostic framework
Authors: Hauser Seraphine , Grams Christian M. , Riemer Michael , Knippertz Peter , Teubler Franziska
Published: March 2021

Quasi-stationary, persistent, and recurrent states of the large-scale extratropical circulation, so-called weather regimes, characterize the atmospheric variability on sub-seasonal timescales of several days to a few weeks. Weather regimes featuring a blocking anticyclone are of particular interest due to their long lifetime and potential for high-impact weather. However, state-of-the-art numerical weather prediction and climate models struggle to correctly represent blocking life cycles, which results in large forecast errors at the medium-range to sub-seasonal timescale. Despite progress in recent years, we are still lacking a process-based conceptual understanding of blocked regime dynamics, which hinders a better representation of blocks in numerical models. In particular the relative contributions of dry and moist processes in the onset and maintenance of a block remain unclear.

Here we aim to revisit the dynamics of blocking in the Euro-Atlantic region. To this end we investigate the life cycles of blocked weather regimes from a potential vorticity (PV) perspective in ERA5 reanalysis data (from 1979 to present) from the European Centre for Medium-Range Weather Forecasts. We develop a diagnostic PV framework that allows the tracking of negative PV anomalies associated with blocked weather regimes. Complemented by piecewise PV-tendencies - separated into advective and diabatic PV tendencies - we are able to disentangle different physical processes affecting the amplitude evolution of negative PV anomalies associated with blocked regimes. Most importantly, this approach newly enables us to distinguish between the roles of dry and moist dynamics in the initiation and maintenance of blocked weather regimes in a common framework. A first application demonstrates the functionality of the developed PV framework and corroborates the importance of moist-diabatic processes in the initiation and maintenance of a block in a regime life cycle. 
Mechanism of hyperaccumulation of heavy metals by of Verbascum thapsus from soil
Authors: Chernikova Natalia , Chaplygin Victor , Nevidomskaya Dina , Ghazaryan Karen , Mandzhieva Saglara , Minkina Tatiana , Movsesyan Hasmik , Glinushkin Alexey , Kalinichenko Valery , Beschetnikov Vladimir , Sazonov Ilia
Published: March 2021

The impact of inorganic pollutants in the zone of industrial wastewater settling tanks (South of Russia) was studied. The levels of Mn, Cr, Ni, Cu, Zn, Pb, Cd were determined for Verbascum thapsus L., which are part of the mesophilic succession of wild plants in the studied technogenically polluted territory. V. thapsus L. has been described as a species with great phenotypic plasticity and the capacity for ecotypic differentiation. The bioavailability of heavy metals (HM) for V. thapsus L. from transformed soils has been established. Anatomical and morphological features in the tissues of the plants affected by heavy metals were analyzed using light-optical and electron-microscopic methods. Contamination of the soil cover with Mn, Cr, Ni, Cu, Zn, Pb and Cd has been established with maximum content of Zn. The excess of the maximum permissible levels of pollution with Zn, Pb, Cr and Cd regulated in the Russian Federation was by 1.2, 16, 36 and 246 times higher, respectively analyzing V. thapsus L. The lower level of heavy metal content in the inflorescences in comparison with the root system, stems and leaves indicates the resistance of generative organs to technogenic pollution. In the root and leaves of V. thapsus L. the anatomical and ultrastructural observation was carried out using light-optical and transmission electron microscopy. Changes in the ultrastructure of plants under the influence of anthropogenic impact have been revealed. The most significant changes of the ultrastructure of the polluted plants were found in the cell organelles of leaves (mitochondria, plastids, peroxisomes, etc.) including the spatial transformation of the thylakoid system of plastids during the metal accumulation by plants. The study of the plant tissues role in the elements translocation and accumulation is necessary for understanding the mechanism of hyperaccumulation of HMs by plants.

The research was financially supported by the RFBR, projects no. 18-29-25071 and 20-55-05014.
Short-term response to vermicompost amendment of chemical and biochemical properties of soil under greenhouse farming
Authors: Coppola Giuseppe Paolo , Di Rauso Simeone Giuseppe , Vairo Francesco , Caputo Michele , Amalfitano Carmine , Zaccardelli Massimo , Rao Maria A.
Published: March 2021

Intensive cultivation of greenhouse crops can damage soil quality due to higher micro-environmental temperatures than field crop production, the absence of rotations, the preference of milling to ploughing, the mineral fertilization and the removal of crop residues without the organic matter reintegration. The compost addition to agricultural soil mainly enhances the organic matter content having, in turns, effects in improving physical, chemical, biochemical and microbiological soil properties, preventing erosion, increasing water holding capacity, cation exchange capacity, nutrient absorption by plants. Further a progressive carbon sequestration in soil with the consequent mitigation of climate changes occurs whereas the non-use of organic fertilizers produces a loss in C stock in soil as carbon dioxide in the atmosphere. The degradation of soil quality is reflecting on the crop yields of the ready-to-eat food of the Plain of Sele river in Campania region in South Italy.

Objectives of this research was to assess the short-term effect of vermicompost as organic soil conditioner in place of other organic fertilizers under conventional farming. Vermicompost derived from digestate obtained in anaerobic digestion plant of the Plain of Sele using, as ingestate, livestock sewage, olive mill wastewater and whey from dairy industry. Soil solarization was carried out during the summer to control weeds and soil pathogens. The chemical and biochemical properties of soils sampled after 4 days from soil amendment were investigated to determine the correlation between the use of vermicompost as organic soil conditioner and C stock, nutrient availability, and crop yields. Solarization negatively affected soil respiration and overall enzymatic activities compared to plots without the treatment. Vermicompost as well as pellet, used as other organic soil conditioner, increased soil respiration only in not solarized plots. Conversely no significant changes in term of microbial biomass carbon among treatments occurred. Different responses in terms of crop yields of rocket were observed in plots cultivated under diverse treatment: solarized plots produced greater amount of rocket than not solarized plots and plot amended with vermicompost showed the best performance among solarized ones.

This work was part of the project “Sustainable management of soil fertility in the Sele Plain to produce ready-to-eat food as cover crops through organic amendment deriving from local livestock sector” funded by PSR Campania 2014/2020.
Sub-ion magnetic holes in the plasma injection region: origins and dynamics
Authors: Shustov Pavel , Artemyev Anton , Volokitin Alexander , Vasko Ivan , Zhang Xiao-Jia , Petrukovich Anatoliy
Published: March 2021

Recent spacecraft observations of plasma injections reveal abundance of small-scale nonlinear magnetic structures – sub-ion magnetic holes. These structures contribute to magnetosphere-ionosphere coupling and likely responsible for energetic electron scattering. Sub-ion magnetic holes propagate in plasma of two electron components with very different temperatures. Properties of such holes resemble properties of classical magnetosonic solitary waves propagating across the ambient magnetic field, but observations suggest that these holes do not disturb background ions. This study aims to generalize the linear theory of magnetosonic waves by including two electron components. In analog to the electron acoustic mode, cold electrons can act as ions for the generation of magnetosonic mode waves. This unstable electron magnetosonic mode can explain all properties of sub-ion holes in observations. We suggest that sub-ion holes can form during the nonlinear evolution this electron magnetosonic mode. We consider an adiabatic model for investigation of such nonlinear evolution and electron dynamical response to evolving hole electromagnetic field. This model describes slow formation of sub-ion magnetic holes from low-amplitude limit. The adiabatic electron response to such formation can include both electron colling and heating, for populations with different pitch-angles.

The work was supported by the Russian Scientific Foundation, project 19-12-00313.
Full-waveform inversion of the African Plate
Authors: van Herwaarden Dirk-Philip , Afanasiev Michael , Thrastarson Sölvi , Fichtner Andreas
Published: March 2021

We present a full-waveform inversion (FWI) of the African plate. Starting from the Collaborative Seismic Earth Model, we invert seismograms that are filtered to 35 s and compute gradients using the adjoint state method. This FWI uses a novel approach that we introduced earlier with the name Evolutionary FWI.

In contrast to conventional waveform inversion, our approach uses dynamically changing mini-batches (subsets of the full dataset) that approximate the gradient of the larger dataset at each iteration. This has three major advantages, (1) We exploit redundancies within the dataset, which results in a reduced computational cost for model updates, (2) The size of the complete dataset does not directly impact the computational cost of an iteration, thereby enabling us to work with larger datasets, and (3) The nature of the algorithm makes it trivial to assimilate new data, as the new data can simply be added to the complete dataset from which the mini-batches are sampled.

The aforementioned advantages enable us to extend the boundaries of what was previously possible for a given computational budget. We perform more than 80 mini-batch iterations and invert waveforms from over 400 unique earthquakes. This has the same cost as 8 iterations with all data. Our latest model clearly images tectonic features such as the Afar triple junction as well as slow zones below areas with dynamic topography, such as the Tibesti and Hoggar mountain ranges.
Estimation of water holding capacity of soils using data from different types of particle size analyses
Authors: Horváth Adrienn , Makó András , Bidló András , Szecsődi Orsolya
Published: March 2021

Determining the particle size distribution of soils helps to monitor the hydrophysical properties of the soil (e.g. water conductivity or water holding capacity). Climate change increases the importance of water retention and permeability, as extreme weather events can severely impair the water supply of drought-prone plant stocks. The amount of water is expected to decrease. At the beginning of the research, we have developed a measurement method to replace the classical “pipette” sedimentation method with the laser diffraction method. The theoretical background of laser diffraction measurements is already known, but its practical application for estimating soil’s water holding capacity is uncommon in detail. The developed, modified Thornthwaite model considers soil properties (e.g. root depth, topsoil layer thickness) and size distribution (silt and clay fraction) of soil particles combined with the most significant soil properties. The pre-sieving of soil aggregates, the pre-treatment (disaggregation and dispersion) of the samples greatly influence the obtained results. In addition to the sedimentation method, instrumental measurements (Mastersizer 3000) were applied with three variants of pre-treatment. For comparison, the results of a Leptosol, a Cambisol, and a Luvisol were prepared for the first modified Thornthwaite water balance model. Significant differences appeared especially during drought periods that could be a basis for studying the drought sensitivity of soils. By the development of our method, the water holding capacity of soil can be estimated; therefore, adapting forest management could be planned against climatic and pedological transformations.
Co-developing a data and knowledge portal to support stakeholder risk assessments with uncertain, global, multi-model based information on hydrological hazards of climate change
Authors: Kneier Fabian , Cáceres Denise , Dietrich Stephan , Schwanenberg Dirk , Köthe Harald , Döll Petra
Published: March 2021

Successful adaptation to climate change worldwide will require many local climate change risk assessments. However, appropriate and tailored climate services and information tools are lacking, particularly in developing countries. Co-produced, user-driven climate services are a recognized means for effective generation and provisioning of relevant climate information and support the utilization by decision-makers, enabling them to account for climate change in their risk portfolios. In the CO-MICC project (ERA4CS), a data and knowledge portal is co-developed with stakeholders based on global-scale multi-model simulations of hydrological variables. In a participatory manner, we focussed on (1) eliciting the relevant hydrological hazard indicators, (2) representing their uncertainty quantitatively in a way that is both scientifically correct and utilizable to the diverse users of the hazard information, and (3) creating guidance on how to integrate the uncertain global information into regional-scale assessments of water-related climate change risk and adaptation assessments. Adapting the tandem framework of the Swedish Environmental Institute (SEI), participatory stakeholder dialogues including seven workshops with stakeholders from focus regions in Europe and Northern Africa, and finally with globally-acting companies serve to integrate the various experiences, needs and expectations of various regions and users. Participants included local researchers, experts from meteorological services and decision-makers from regional and national hydrological agencies. Together, we co-produced relevant model output variables and appropriate end-user products encompassing static and dynamically generated information in a web portal. The global-scale information products include interactive maps, diagrams, time series graphs, and suitably co-developed statistics, with appropriate visualization of uncertainty. In complement, the knowledge tool provides transparent meta-information, tutorials and handbook guidelines to utilize the provided information in models of local participatory risk assessments. While CO-MICC enables access to this information to a broad range of stakeholders from around the world (policy makers, NGOs, the private sector, the research community, the public in general) for their region of interest, it additionally sheds light on the optimal design and methods of co-development processes.
A GIS based application of Benfratello's method to estimate the irrigation deficit in a semiarid climate
Authors: Barontini Stefano , Rapuzzi Cesare , Peli Marco , Ranzi Roberto
Published: March 2021

Benfratello's Contribution to the study of the water balance of an agricultural soil (Contributo allo studio del bilancio idrologico del terreno agrario) was firstly published sixty years ago, in 1961. The paper provides a practical conceptual and lumped method to determine the irrigation deficit in agricultural disctricts. Since then, it has been used in many areas in Southern Italy.

According to the method, percolation and capillary rise from the groundwater table are absent, and surface runoff happens only when the soil capability of storing water is exceeded. The method is therefore suitable for semiarid (and eventually arid) climates. Dry and wet seasons are defined on a climatic basis, as the season during which potential evapotranspiration is greater than precipitations (and the stored soil--water decreases), and that during which precipitations exceed potential evapotranspiration (and the stored soil--water inccreases).

With these hypotheses, Benfratello proposed to adopt a power--relationship (with power m greater or equal to 0) to assess the ratio between the actual and the potential soil--water loss, as a function of the ratio between the stored soil--water and the maximum available storage. The solution provides, in a simple closed form, the actual soil--water loss as a function of the potential loss (which is a climatic characteristic), and generalizes previous approaches, viz Thorthwaite (1948) and Thornthwaite and Mather (1955) ones, for which m = 0 and m = 1, respectively.

In this contribution we present a GIS based application of Benfratello's method to assess the soil water balance and the irrigation deficit of the semiarid Capitanata plane (4550 km2, Southern Italy), one of the most important agricultural districts in Italy. A comparison between the method and previous results for the same region will be provided as well. Due to its simplicity and to the small number of needed parameters, Benfratello's method might be regarded to as an effective tool to assess the effects of climatic, landuse and anthropogenic change scenarios on the soil water balance and on the irrigation deficit.
Organic Vapor Condensation in Pyro-cumulonimbus Outflow Explains Large Stratospheric Smoke Mass Injection and Thickly Coated Black Carbon
Authors: Dubey Manvendra K. , Gorkowski Kyle , Reisner Jon , Benedict Katherine , Josephson Alex , Koo Eunmo , D'Angelo Gennaro , Peterson David , Guimond Steve
Published: March 2021

Airborne measurements of upper troposphere and lower stratosphere biomass burning smoke show a large size mode at 350nm radius. Furthermore,  very thickly coated black carbon (300-400nm radius) is observed in 2 month aged Pyro-cumulonimbus (PyroCb) smoke in the lower stratosphere. Finally, the stratospheric aerosol mass injections from the 2017 British Columbia (BC17) PyroCbs are much larger than fuel loading predicts.  We propose a secondary organic aerosol (SOA) production mechanism where volatile organic compounds (VOCs) emitted by fires condense in the cold convective PyroCb updrafts to explain the aforementioned data. Observations supporting this mechanism present in FIREX-AQ, ATOM and CARIBEC airborne data are synthesized. The condensation, evaporation and coagulation mechanisms are implemented into LANL’s large eddy cloud resolving model called HIGRAD.  Our simulations provide insights into the vertical distribution of SOA in the BC17 PyroCb and the role of warm and ice clouds in lofting it into the lower stratosphere. We show that SOA formation can increase aerosols by a factor of 2-3 and latent heat from warm and ice clouds adds 5 km to the injection height of BC17 fire smoke. The fate, transport and impacts  of smoke from BC17 and 2020 Australian fires are examined using climate model (CESM) simulations.  
Constraint of Active Deformation between the African Platform and the Maghrebian Thrust Belt: Current Plate Motion from Permanent GNSS data in Algeria
Authors: Meghraoui Mustapha , Abdellaoui Hassen , Masson Frédéric
Published: March 2021

The kinematic of tectonic motions between the African (Sahara) platform and the Maghrebian thrust belt remained unexplored since the onset of space geodesy. Here, we use data of 6 permanent GNSS stations located north and south of the Atlas thrust belt in Algeria to constrain shortening and transpression at the tectonic boundary. The permanent GPS data and results are obtained from the network in Algeria operative from 2013 to 2019, presented with the results of the REGAT network in Algeria since 2007. The south Atlas suture zone constitutes the limit between African (Sahara) shield domain considered as a stable continental interior and the Sahara Atlas that belong to the Alpine orogeny. The tectonic boundary is marked by a E-W to ENE-WSW, en echelon fold belt system with deformed Plio-Quaternary formations to the North and flat laying Mesozoic and Tertiary sedimentary units south of the suture zone. The GNSS data are processed using Gamit-GlobK and results show tectonic motions with a predominant 5 to 6 mm/yr velocities trending NNW-SSE to NW-SE (westward) in the Sahara Platform. The GPS velocities show uniform trend in the African platform from which we infer 0.5 to 1.0 mm/yr convergence across the south Atlas suture zone. The intraplate convergence is attested by the moderate but permanent seismic activity at the tectonic boundary.
Heat Events in the Indian Subcontinent under a warming climate scenario: Detection and its Drivers 
Authors: Kapoor Ritika , Alvarez-Castro Carmen , Scoccimarro Enrico , Materia Stefano , Gualdi Silvio
Published: March 2021

Rising global temperatures are a potential cause for increase of extreme climate events, such as heat waves, both in severity and frequency. Under an increasing extreme event scenario, the world population of mid- and low-latitude countries is more vulnerable to heat related mortality and morbidity.

In India, the events occurred in recent years have made this vulnerability clear, since the numbers of heat-related deaths are on a rise, and heat waves can impact various sectors including health, agriculture, ecosystems and the national economy.

Preliminary results show the prevalence of heat events in seven different regions of India during the pre-monsoon (March, April, May) and transitional (May, June, July) months. We consider daily maximum temperatures (Tmax) and the NOAA’s Heat Index (HI), a combination of temperature and relative humidity that gives an insight into the discomfort because of increment in humidity.

We look into various drivers behind the heat events in the seven different clusters, in particular ENSO and the North Atlantic Regimes that have been linked to the generation of heat waves in different parts of India. The preliminary results indicate Nino 3.4 SST anomalies show positive correlation with Tmax anomalies only in the western coast during pre-monsoon season, while in the transitional months positive correlation extends to central and east India. The Tmax composite anomalies for the cold, warm and neutral phases of ENSO show positive anomalies for only warm years and negative anomalies for the cool and neutral years. Heat Index shows similar spatial patterns for correlation analysis and composite anomaly analysis. The Mean Sea Level Pressure (MSLP) composite associated with heat waves (days exceeding 95th percentile=>3 days) show a persistent ridge over the North Atlantic region.

 
Collapse of a weakly cohesive granular column
Authors: Szuszik Csanád , Kun Ferenc
Published: March 2021

Natural catastrophes like landslides are often caused by the nucleation and propagation of fractures in heterogeneous materials. Landslides are typically initiated by heavy raining events when water penetrates the pores and reduces the cohesion of soils leading to instability and cracking. When it happens on a steep slope, the moving mass could break up into pieces and the landslide gives rise to a debris flow composed of rapidly traveling fragments of soil and rocks. Such devastating catastrophes endanger the infrastructure and take thousands of lives every year.

In order to understand the emergence of landslides and debris flows we investigated the collapse of a granular column under the action of gravity by means of discrete element simulations. In the model, a cylindrical sample of soil is represented as a random packing of spherical particles. Cohesion is introduced by connecting the particles with non-linear spring elements along the edges of Delaunay triangles determined in the initial configuration of the particles. The constitutive law of springs captures the elastic behavior of particle contacts at small deformations, the plasticity beyond a yield threshold, and the gradual softening and final breaking at large separation distances. A very important feature of the interaction is that particle contacts can be healed, i.e. if two particles approach each other within a capture distance, a new cohesive contact is established between them. Computer simulations were performed varying the strength of cohesion in a broad range.

Our calculations revealed that at high cohesion the granular column sinks in, i.e. its height gradually decreases while it undergoes restructuring and flattening, however, in the final state the system keeps its integrity. When the cohesion is sufficiently week, the process of collapse cannot stop: the system breaks up into a large number of fragments which run out at a high speed. The two phases of high and low cohesion represent the mass movement and the debris flow states of real landslides, respectively. We demonstrate that the transition occurs at a critical cohesion showing analogies to continuous phase transitions.
Energy Dissipation at Filamentary Structures Downstream of the Earth’s Parallel Bow Shock
Authors: Kucharek Harald , Gingell Imogen , Schwartz Steven , Farrugia Charles , Trattner Karlheinz
Published: March 2021

While the Earth’s bow shock marks the location at which the solar wind is thermalized, recent publications provided evidence that filamentary structures such as reconnecting current sheets at the shock ramp region may participate in the thermalization process.  Small scale filamentary structures are distinct features that are abundant at the shock and inside the magnetosheath. These structures are not limited to current sheets but include electric and magnetic field enhancements. They may consist of a single or multiple filaments.  They originate from energy dissipation at and downstream of the bow shock, in particular the parallel bow shock. 

We have studied several crossings of the magnetosheath made by the MMS spacecraft, characterising and quantifying the occurrence and consequences of current sheets and field enhancements in terms of local plasma heating and ion acceleration far downstream of the shock. These observations suggest that a combination of current sheet formation, and electric field and magnetic field gradients can contribute to local downstream ion acceleration, and heating. The associated turbulence is likely a consequence of solar wind input parameters. These observations provide evidence that under certain plasma conditions these filamentary structures can play a significant role in thermalizing of the magnetosheath plasma as it propagates further downstream toward the magnetopause, thus augmenting the effect due to the bow shock itself.
Occurrence of microplastics at Wastewater Treatment Plants in the Guadalete-Barbate river basin (Cadiz, Spain).
Authors: Franco del Pino Ana Amelia , Albendín Gemma , Arellano Juana María , Egea-Corbacho Lopera Ágata , Martín García Ana Pilar , Rodríguez Rocío , Quiroga José María , Coello Dolores
Published: March 2021

The increase in microplastics (MPs) research has aroused awareness about their presence and polluting potential in aquatic environments. Wastewater treatment plants (WWTPs) have been identified as one of the main paths for these pollutants to reach the environment. The present study is focussed in the WWTPs emplaced within the Guadalete-Barbate river basin. This geographical area comprises a total of 60 WWTPs treatment plants with an inhabitant equivalent (IE) above 250. Within these 60 wastewater treatment plants, there are 38 plants with conventional treatments and an estimated population of over 800,000. The high percentage of population that lives in this basin leads us to think about the quantity of microplastics that are dumped into the environment daily. Therefore, the aim of this research is to study the occurrence and identify the type of microplastics in these facilities, this information is important in order to design treatments that improve microplastics removal and avoid their entrance in the aquatic environment.
Two extreme rain events over the Atacama Desert and their consequences on the surface: Insights from Change Vector Analysis applied to Landsat 8 OLI imagery
Authors: Olivares Lester , Jordan Teresa , Philpot William , Lohman Rowena
Published: March 2021

In March of 2015 there was probably the most studied rain event that ever occurred in the Atacama Desert. Three days of heavy rain impacted the southern region, with peak amounts of 85 mm locally. Different approaches have been used to study this event, including field observations, isotopic analysis and examination of InSAR data. During February of 2019 there was another rain event in the northern Atacama Desert, during which over 160 mm of rain fell on the eastern part of the Atacama, and the influence on the surface is still unknown. This study examines both events. The two study areas have different relationships to the rain: the 2015 event is analyzed within the area in which it rained, whereas the 2019 study area is 60 km away from the heavy rain, connected by surface water drainage. Results of particular interest are the variable responses of the different types of surface materials (e.g., varying classes of terrain roughness and mineralogy) and the identification of locations of erosion and deposition.

We examine multispectral satellite imagery from the Landsat 8 satellite, an approach that has some advantages over other methods. Advantages include its free access, a longer historical record that may allow examination of more events, and the existence of observations at multiple wavelengths which allows evaluation of mineral phase changes due to the rain, vegetation increment and changes in the type of material.

In this work we apply Change Vector Analysis (CVA) (Bruzzone and Fernandez, 2000) to Landsat 8 OLI images to, first, validate the multispectral satellite CVA results using as ground truth the InSAR permanent coherence loss from the 2015 event. Then we apply the method to identify changes due to the 2019 rain event. We compared these results to our field observations.

Our results indicate that: 1) CVA applied to Landsat bracketing the 2015 rain event identifies the depositional and erosional areas, correlating well to permanent changes detected by InSAR coherence loss. 2) Surface materials react variably, and some categories of materials changed more due to a rain than others. 3) Spectral analysis and CVA do not detect mineralogic phase responses documented by surface data. 4) Wind driven changes were also detected in some areas. 5) Field observations reveal that erosion and deposition are always well identified by the algorithm as long as the extent of change is larger than the pixel size. 6) The distribution of changes is dependent on surface slope.

Reference

Lorenzo Bruzzone and Diego Fernández Prieto. Automatic Analysis of the Difference Image for Unsupervised Change Detection. Technical Report 3, 2000. DOI: 10.1109/36.843009
Magnetic vector inversion using  XYZ measured by fluxgate magnetometer in UAV 
Authors: Karinen Arto
Published: March 2021

Traditionally, the inversion of magnetic data assumes the magnetization of the local geology to run parallel to the Earth’s internal magnetic field that is usually modelled using International Geomagnetic Reference Field (IGRF). Assuming the magnetization parallel to the main field, only the total (scalar) magnetic data are the sufficient input for the inversion of source susceptibility.

Local magnetization may alter from the main field direction in areas of remanent magnetization. Recently, magnetization vector inversion (MVI) using the total field has become an important tool trying to distinguish magnetic data affected by remanenence. Total field as a scalar field exclude all information of the direction of the internal magnetization and more information is required to reveal any remanent magnetization from the main field direction.  Compared to total field using the 3-component XYZ vector magnetic measurements provide more information of the source.  More measurements increase the unambiguous nature of data and may reveal the areas of possible remanence. 

To measure XYZ vector magnetic field we use fluxgate 3-component magnetometer with rigid installation on a fixed-wing UAV. With the help of accurate inertial measurement units the measured magnetic field can be determined in the direction of fixed coordinate system. The components of the measured magnetic field rotated into the geographical coordinate represent the magnetic field at survey area.

UAV survey provided the data as the input for the inversions. We made the inversion separately for both susceptibility and magnetization vector. Susceptibility inversion means inversion of induced magnetization, i.e., a single component of magnetization parallel to the main field direction. Magnetization vector inversion, however, resolves all three components of magnetization, which may or may not include remanent magnetization in addition to induced one.

The benefits from utilizing XYZ components of the magnetic field with magnetization inversion seem promising in finding remanenence magnetization.

 

 
On the effect of sea level increases during the Storm Gloria
Authors: Pérez Gómez Begoña
Published: March 2021

The final extent of coastal impacts during extreme events depends on a complex combination of factors (coastal morphology, infrastructures, population, economic activities), and meteorological and oceanographic variables interacting at different spatial and temporal scales (e.g.: precipitation, atmospheric pressure, wind, waves, currents and sea level). Coastal sea level is a key driver of most of these impacts, starting by the increased vulnerability of worldwide coastlines due to mean sea level rise. In January 2020, the storm Gloria hit the Western Mediterranean Sea causing severe coastal damages, destruction of infrastructures, flooding and several casualties. The dynamic evolution of sea level during this storm is presented, demonstrating its contribution to the mentioned impacts at different timescales: long-term sea level and seasonal changes, tides and storm surges, and higher frequency oscillations of the order of minutes, associated with different forcing agents like wind-waves, wind and atmospheric pressure variations or edge waves. Tide gauge data are used as the main source of information including the detection and characterization of record-breaking high-frequency oscillations, (infragravity waves, meteotsunamis, resonance effects), thanks to a new software that operationally characterizes these processes from 2Hz raw data. The storm surge component, that also beat the record along Valencia coastline, is analyzed with in-situ data and model outputs from different operational forecasting systems in the region. The exercise shows the difficulty of disentangling different wave, wind and atmospheric pressure contributions to sea level increase during a storm.  
Satellite-derived shorelines reveal fascinating dynamics for the last three decades on Danube Delta coast
Authors: Tatui Florin , Anghelin Georgiana , Constantin Sorin
Published: March 2021

Shoreline, as the interface between the upper shoreface and the beach-dune system, is sensitive to all changes from both the underwater and sub-aerial parts of the beach at a wide range of temporal scales (seconds to decades), making it a good indicator for coastal health. While more traditional techniques of shoreline monitoring present some shortcomings (low temporal resolution for photointerpretation, reduced spatial extension for video-based techniques, high costs for DGPS in-situ data acquisition), freely available satellite images can provide information for large areas (tens/hundreds of km) at very good temporal scales (days).

We employed a shoreline detection workflow for the dynamic environment of the Danube Delta coast (Black Sea). We focused on an index-based approach using the Automated Water Extraction Index (AWEI). A fully automated procedure was deployed for data processing and the waterline was estimated at sub-pixel level with an adapted image thresholding technique. For validation purposes, 5 Sentinel-2 and 5 Landsat based results were compared with both in-situ (D)GPS measurements and manually digitized shoreline positions from very high-resolution satellite images (Pleiades – 0.5 m and Spot 7 – 1.5 m). The overall accuracy of the methodology, expressed as mean absolute error, was found to be of approximately 7.5 m for Sentinel-2 and 4.7 m for Landsat data, respectively.

More than 200 Landsat (5 and 8) and Sentinel-2 images were processed and the corresponding satellite-derived shorelines between 1990 and 2020 were analysed for the whole Romanian Danube Delta coast (130 km). This high number of shorelines allowed us the discrimination of different patterns of coastline dynamic and behaviour which could not have been possible using usual surveying techniques: the extent of accumulation areas induced by the 2005-2006 historical river floods, the impact of different high-energy storms and the subsequent beach recovery after these events, the alongshore movement of erosional processes in accordance with the dominant direction of longshore sediment transport, multi-annual differences in both erosional and accumulation trends. Moreover, a very important result of our analysis is the zonation of Danube Delta coast based on multi-annual trends of shoreline dynamics at finer alongshore spatial resolution than before. This has significant implications for future studies dealing with different scenarios of Danube Delta response to projected sea level rise and increased storminess.

The presented approach and resulting products offer optimal combination of data availability, accuracy and frequency necessary to meet the monitoring and management needs of the increasing number of stakeholders involved in the coastal zone protection activities.
Modeling evaporation from northern waterbodies, the case of an 85-km2 reservoir
Authors: Kallel Habiba , Mackay Murray , Thiboult Antoine , Nadeau Daniel , Anctil François
Published: March 2021

Freshwater bodies represent 9% of Canada’s total land area, with more than half of these having a surface area smaller than 100 km2. Taking into account the interactions between lakes and the atmosphere in meteorological models is crucial, considering the marked differences with the surrounding land masses (low albedo, unlimited source of water, high thermal capacity, etc.). Open water evaporation, in particular, is often a challenge because of its intangible nature and the scarcity of direct observations. This project focuses on the modeling of the surface energy budget of a reservoir located in the boreal biome of eastern Canada, with an emphasis on the evaporation. Observations are available for the 85-km2 La Romaine 2 hydroelectric reservoir (50.7°N, 63.2°W), where two micrometeorological towers were deployed: one operated yearlong on the shore and one operated on a floating deck during ice-free conditions. Modeling resorts to the Canadian Small Lake Model (CSLM), a one-dimensional land surface model designed to integrate the lake-atmosphere fluxes into meteorological models. The model also simulates the thermal regime of the water body, including ice formation. Lastly, the model can be used for climate and weather prediction, which may be a useful for reservoir management. Comparison of field observations and simulations confirms the CSLM ability to reproduce the turbulent fluxes and the temperature behavior of the reservoir except for some specific periods, in particular the ice breakups and freeze-ups. The model somehow underestimates the water temperature resulting in a premature depletion of the lake heat storage in autumn. It also overreacts to high wind episodes.
Long-term structural monitoring of multi-story RC structures, based on data extracted from ambient noise and earthquake vibrations
Authors: Tiganescu Alexandru , Grecu Bogdan , Craifaleanu Iolanda-Gabriela , Toma-Danila Dragos , Balan Stefan-Florin
Published: March 2021

The impact of natural hazards on structures and infrastructures is a critical issue that needs to be properly addressed by both public and private entities. To better cope with seismic hazard and to mitigate the risk, long-term multi-sensor infrastructure monitoring represents a useful tool for acquiring information on their condition and vulnerability. However, the current increasing data volume collected using sensors is not suitable to be processed with classical standalone methods. Thus, automatic algorithms and decision-making frameworks should be developed to use this data, with minimum intervention from human operators. A case-study for the application of advanced methods is focused on the headquarters of the Institute for Atomic Physics, a 11-story reinforced concrete building, located near Bucharest, Romania. The instrumentation scheme consists of accelerometers installed at the basement, at an intermediate floor and at the top of the structure. The data were continuously recorded, starting with December 2013. More than 80 seismic events with moment magnitude, MW, larger than 3.8 were recorded during the monitoring period. The current study covers the long-term evolution and variation of dynamic parameters (one value per hour), based on both ambient noise sources and small and medium magnitude seismic events. The seasonal variation of these parameters will be determined, as well as their daily variation and the differences between values obtained from ambient noise and from earthquake-induced vibrations. Other atmospheric parameters (e.g. temperature, precipitation, wind speed) will be considered in future studies. The goal of the PREVENT project, in the framework of which the research is performed, is to collect multi-disciplinary data and to integrate them into a complex monitoring system. The current study achieved the first step, focusing on data from the seismic sensors and setting up the premises for a multi-sensor, multi-parameter, more reliable infrastructure monitoring system.  
Permafrost-derived dissolved organic matter character controls microbial community composition in Arctic coastal waters
Authors: Bruhn Anders Dalhoff , Stedmon Colin A. , Comte Jérôme , Matsuoka Atsushi , Speetjens Neik Jesse , Tanski George , Vonk Jorien E. , Sjöstedt Johanna
Published: March 2021

Climate warming is accelerating erosion rates along permafrost-dominated Arctic coasts. To study the impact of erosion on marine microbial community composition and growth in the Arctic coastal zone, dissolved organic matter (DOM) from three representative glacial landscapes (fluvial, lacustrine and moraine) along the Yukon coastal plain, are provided as substrate to marine bacteria using a chemostat setup. Our results indicate that chemostat cultures with a flushing rate of approximately a day provide comparable DOM bioavailability estimates to those from bottle experiments lasting weeks to months. DOM composition (inferred from UV-Visible spectroscopy) and biodegradability (inferred from DOC concentration, bacterial production and respiration) significantly differed between the three glacial deposit types. DOM from fluvial and moraine deposit types shows more terrestrial characteristics with lower aromaticity (SR: 0.63 (±0.02), SUVA254: 1.65 (±0.06) respectively SR: 0.68 (±0.00), SUVA254: 1.17 (±0.06)) compared to the lacustrine deposit type (SR: 0.71 (±0.02), SUVA254: 2.15 (±0.05)). The difference in composition of DOM corresponds with the development of three distinct microbial communities, with a dominance of Alphaproteobacteria for fluvial and lacustrine deposit types (relative abundance 0.67 and 0.87 respectively) and a dominance of Gammaproteobacteria for moraine deposit type (relative abundance 0.88). Bacterial growth efficiency (BGE) is 66% for moraine-derived DOM, while 13% and 28% for fluvial-derived and lacustrine-derived DOM respectively. The three microbial communities therefore differ in their net effect on DOM utilization. The higher BGE value for moraine-derived DOM was found to be due to a larger proportion of labile colourless DOM. The results from this study, therefore indicate a substrate control of marine microbial community composition and activities, suggesting that the effect of permafrost thaw and erosion in the Arctic coastal zone will depend on subtle differences in DOM related to glacial deposit types. These differences further determines the speed and extent of DOM mineralization and thereby carbon channelling into biomass in the microbial food web. We therefore conclude that marine microbes strongly respond to the input of terrestrial DOM released during coastal erosion of Arctic glacial landscapes.