bluuebunny/crossref_metadata_2025 huggingface dataset:
Geomophological and vulnerability analysis of a coastal delta under increased hydrological alteration over the past two centuries: Tana River delta, Kenya, East Africa.
Authors: Gitau Peter , Duvail Stéphanie , Verschuren Dirk , Guillaud Dominique
Published: March 2021

Coastal deltas worldwide are under risk of degradation due to the increasing impacts of sea-level rise, and continuous human alterations of river basin hydrology. This research highlights the geomorphological changes that have occurred within the Tana River delta in Kenya, an important deltaic ecosystem of high biodiversity value in East Africa.

The geomorphological features (river channels, floodplain, coastal dune system) and their evolution over the past two centuries were described. Aerial and satellite imagery was used to assess the magnitude and distribution of coastal changes from the 1960s to present.  Additionally, sediment cores recovered within the mangrove environment were analysed to establish the succession of sedimentation periods and patterns. Finally, we explored the response of the coastal processes of deposition and erosion under anthropogenic alterations of the hydrological system.

It was established that over the past two centuries Tana River has changed its main channel and outlet to the Indian Ocean on three occasions. A first river avulsion occurred in the 1860s, followed by a second avulsion in the late 1890s that was promoted by human interference through channel expansion and dyke construction. The third change in river course has occurred gradually over the past 20 years, amid human efforts to engineer the river channels.

From the sediment analysis and radiocarbon dating, it is ascertained that the lower deltaic region developed rapidly over the past ~180 years, facilitated by increased sedimentation from the main Tana River. On the other hand, analysis of the coastline changes indicate that there has been increased erosion of the coastal dune system and mangrove vegetation along the former river outlet, leading to rapid marine intrusion into local subsistence farming areas. By analysing the combined impacts of both natural river dynamics and human alteration we highlight how the integrity of the Tana River delta has increasingly become vulnerable under present sea level rise and continued upstream river alteration.
Investigation of runoff generation and Radon-222 activities in a forested catchment using HydroGeoSphere
Authors: Munir Muhammad Usman , Frei Sven
Published: March 2021

Radon (222Rn) is widely used as a natural tracer to investigate surface/groundwater interactions for hydrological systems. Because 222Rn activities in groundwater are higher compared to surface water, it can be used to quantify groundwater inflow rates into rivers and streams. Here we present a process-based model to simulate 222Rn emanation and transport in groundwater to investigate surface/groundwater interactions for the  Große Ohe catchment, located in the Bavarian Forest National Park (Germany). For representing surface and groundwater flow in the catchment as well as transport, decay, and emanation of 222Rn, the processed based hydrological model HydroGeosphere (HGS) is used. HGS is an integrated surface sub-surface hydrological model (ISSHM) which can simulate reactive transport in surface and sub-surface flow. The model was calibrated using measured in-stream 222Rn activities and continuous discharge observations. Main objective of this study is to investigate runoff generation in the catchment and how hydrological processes are affecting the age and residence time composition of groundwater.  
Failure to forecast: A case study in nowcasting and forecasting the eruption of a coronal mass ejection and its geomagnetic impacts on Dec 7-10, 2020. 
Authors: Gallagher Peter , Murray Sophie , Malone-Leigh John , Campanyà Joan , Cañizares Alberto , Carley Eoin , Blake Seán
Published: March 2021

Forecasting solar flares based on while-light images and photospheric magnetograms of sunspots is notoriously challenging, while accurate forecasting of coronal mass ejections (CME) is still in its infancy. That said, the chances of a CME being launched is more likely following a flare. CMEs launched from the western hemisphere and “halo” CMEs are the most likely to be geomagnetically impactful, but forecasting their arrival and impact at Earth depends on how well their velocity is known near the Sun, the solar wind conditions between the Sun and the Earth, the accuracy of theoretical models and on the orientation of the CME magnetic field.  In this presentation, we describe a well observed active region, flare, CME, radio burst and sudden geomagnetic impulse that was observed on December 7-10, 2020 by a slew of instruments (SDO, ACE, DSCOVR, PSP, US and European magnetometers). This was a solar eruption that was not expected, but the CME and resulting geomagnetic impact should have been straight-forward to model and forecast. What can we learn from our failure to forecast this simple event and its impacts at Earth? 
Automated recognition of the landforms origin for the Kola Peninsula based on morphometric variables
Authors: Kharchenko Sergey
Published: March 2021

The trying of automatic creation of the Kola Peninsula geomorphological map [after Grave M.K. et al., 1971] at the morphogenetic legend’s principle was provided based on the "random forest" classification technique. As input data a several geomorphometric variables were used only (the basic variables – elevation, slope angle, curvatures etc., and the relatively rare variables including spectral terrain variables – result of the decomposition of digital elevation model into 2D Fourier series). On the training data covering only 1.3 % study area with known labels for one of thirteen probable landform types, it were carried out the reconstruction of geomorphological boundaries and the automatic creation of the geomorphological map. The accuracy of resulting map was 81 % (area’s share with the correct classification result – the same landform type that expertly way defined). This result gives increasing of accuracy over “zero accuracy” (random guessing) more than x10. In general, a large visual similarity between the expertly created geomorphological map and the one created automatically based on the known typological affiliation of the landforms of a small part of the territory is also noticeable. Mistakenly recognized affiliation to one or another genetic type of landform in 19% of tries is rather not a problem, but a good opportunity to improve the predictive power of the model by targeted search of representative morphometric variables. We emphasize - the obtained accuracy of the model is achieved only when using variables extracted entirely from the DEM and calculated fully automatically. The use of data from tectonic and surficial geology maps, maps of quaternary deposits and other data sources can significantly improve the accuracy of the classification and bring it to the level of confident use of the model in practical work. As a by-product of landform classification by the random forest method - the characteristics that are most representative of the prediction of the genetic types of the landforms of the Kola Peninsula have been identified. Almost all of them turned out to be relatively rarely used focal geomorphometric variables. More standard and familiar parameters - slopes, aspect, curvatures are not characterized by significant representativeness. The predictive power of the model was considerably increased by using the spectral characteristics of the relief (parameters of periodicity of the elevation field, calculated by the sliding window method of two-dimensional discrete Fourier transform). The obtained results, we think, convince us that the possibilities of morphometric indicators alone in general geomorphological mapping are underestimated.

The study was supported by the Russian Science Foundation (project No. 19-77-10036).
Coring of the Paleocene-Eocene Thermal Maximum (PETM) in Denmark: ICDP Project PVOLC
Authors: Jones Morgan , Stokke Ella , Planke Sverre , Augland Lars , Svensen Henrik , Tegner Christian , Sluijs Appy , Frieling Joost , Mather Tamsin , Huismans Ritske
Published: March 2021

The Paleocene-Eocene Thermal Maximum (PETM) is recognized as one of the potential analogues in the geological record for present-day global warming. The aim of the International Continental Scientific Drilling Program (ICDP) project PVOLC is to test the hypothesis that voluminous magmatism in sedimentary basins in the NE Atlantic triggered the PETM. Two ICDP boreholes are planned to core the boundary in the Limfjorden area in Denmark in 2022. PVOLC will be conducted in conjunction with IODP Exp 396 on the mid-Norwegian continental margin. The North Atlantic Igneous Province (NAIP) was is a large igneous province (5–10 million km3 magma) that coincided with both the opening of the NE Atlantic Ocean and the greenhouse conditions of the early Paleogene. The close temporal correlations suggest a possible causal relationship between the NAIP and both the climatic and tectonic changes around 56– 54 Ma. In particular, the main acme of NAIP activity occurred across the Paleocene–Eocene Thermal Maximum (PETM), an extreme hyperthermal event that represents the warmest conditions of the last 60 million years. The NAIP is among several proposed candidates for driving global warming through CO2/CH4 emissions, both by magmatic degassing and through contact metamorphism around shallow intrusions in organic rich sedimentary basins. What is needed to refine the role of the NAIP during the PETM are key sedimentary sequences that contain abundant volcanic and climatic proxies in the same section, thereby allowing a precise geochronology of events to be attained. The sediments exposed on the Fur island, Denmark, are a key sequence of PETM and post-PETM strata with little thermal overprint and hundreds of well-preserved volcanic ash layers from the NAIP. The effects of Quaternary glaciotectonism have disturbed this key stratigraphic interval at Fur, but seismic surveys indicate that undisturbed strata are found a few km to the south. The ICDP PVOLC project plan is to drill both the Paleocene-Eocene and the Cretaceous-Paleocene boundaries, hopefully recovering pristine cores suitable for high-resolution geochemical and climatic studies.
Combining static and dynamic environmental factors at various scales to predict shallow landsliding in South Tyrol, Italy – The Proslide project
Authors: Kohrs Robin , de Vugt  Lotte , Zieher Thomas , Crespi Alice , Rossi Mattia , Greifeneder Felix , Schneider-Muntau Barbara , Ventura Bartolomeo , Rutzinger Martin , Steger Stefan
Published: March 2021

Shallow landslides in alpine environments can constitute a serious threat to the exposed elements. The spatio-temporal occurrence of such slope movements is controlled by a combination of predisposing factors (e.g. topography), preparatory factors (e.g. wet periods, snow melting) and landslide triggers (e.g. heavy precipitation events).  

For large study areas, landslide assessments frequently focus either on the static predisposing factors to estimate landslide susceptibility using data-driven procedures, or exclusively on the triggering events to derive empirical rainfall thresholds. For smaller areas, dynamic physical models can reasonably be parameterized to simultaneously account for static and dynamic landslide controls.  

The recently accepted Proslide project aims to develop and test methods with the potential to improve the predictability of landslides for the Italian province of South Tyrol. It is envisaged to account for a variety of innovative input data at multiple spatio-temporal scales. In this context, we seek to exploit remote sensing data for the spatio-temporal description of landslide controlling factors (e.g. precipitation RADAR; satellite soil moisture) and to develop models that allow an integration of heterogeneous model inputs using both, data-driven approaches (regional scale) and physically-based models (catchment scale). This contribution presents the core ideas and methodical framework behind the Proslide project and its very first results (e.g. relationships between landslide observations and gridded daily precipitation data at regional scale). 
Density-Based Individual Tree Detection from Three-Dimensional Point Clouds
Authors: Camporeale Carlo , Latella Melissa , Sola Fabio
Published: March 2021

The use of three-dimensional point clouds in forestry is steadily increasing. Numerous algorithms to detect individual trees from point clouds and derive some fundamental inventory parameters have been proposed so far, but they usually provide higher accuracy in coniferous stands than in deciduous one. In the latter kind of stands, indeed, the tree identification is hampered by the geometrical round shape of the crowns, the interlacing branches of adjacent trees and the usual presence of understory vegetation.

In an attempt to overcome these limitations, we developed an algorithm that is innovatively based on the areal point density of the three-dimensional cloud and that provides the height and coordinates of all the trees within a region of interest.

In this work, we apply the algorithm to different situations, ranging from the regularly-arranged plantations to the very interlaced crowns of the naturally established stands, demonstrating how it is able to correctly detect most of the trees and recreate a map of their spatial distribution. We also test its capability to deal with relatively low point density and explore the possibility to use it to recreate time series of vegetation biomass. Finally, we discuss the algorithm’s limitations and potentialities, particularly focusing on its coupling to other existing tools to deal with a wider range of applications in forestry and land management.

 
Geochemical survey of Lake Balaton sediments: holocene paleoenvironment and paleoclimate
Authors: Pálfi Ivett , Pósfai Mihály , Kristály Ferenc , Veres Daniel , Arnaud Fabien , Szalai Zoltán , Gresina Fruzsina , Szabó Zoltán , Darabos Gabriella , Korponai János , Czuppon György , Demény Attila , Magyari Enikő
Published: March 2021

In the winter of 2017 three undisturbed sediment cores were retrieved from the Szemes Basin of Lake Balaton. The sediments were sampled for AMS 14C dating and we used 8 of the radiocarbon dates for age-depth modelling. Based on this, the investigated sediment sequence covers the entire Holocene and Late Glacial period and the bottom of the sediment is ca. ~16,000 cal yr BP old. X-ray fluorescence spectrometry (XRF) was used to reconstruct rapid changes in the element content of the lake sediment. The evaluation of the measured results makes it possible to reconstruct the changes in the discharge environment and lake water level that can be related to the climate and human impact. Based on the data, two major evaporation events can be observed at 5500 BP and 8100 BP. These results were also verified by oxygen isotope studies. To reconstruct the energy of the deposition environment, particle size analysis was performed. The obtained results confirmed that river sediments are common at the bottom of Lake Balaton sediments, while biogenic carbonate dominates in the upper, Holocene part of the sediment core. To identify each mineral phase in the sediment, X-ray diffraction (XRD) studies were used to determine the ratio of calcite to Mg-calcite. Based on our XRF measurements, focusing primarily on quantitative changes in magnesium and calcium, transmission electron microscopy (TEM) studies were performed, mainly in the Mg enrichment layer around 8100 BP. The precipitation of biogenic carbonate in Lake Balaton is still taking place, mainly in the form of calcite and Mg-calcite. Their relative proportions strongly depend on the Mg saturation of the water and the substrates on which they are separated. From our results we can draw conclusions about the possible previous deeper phases of the lake and the evaporation conditions of the water. The data obtained from transmission electron microscopy shows a good agreement with the results of the XRF measurement, the proportion of Mg-calcite increases around 8100 BP that likely indicate drier climatic conditions connectable to the well know 8.2 ka cal BP climatic reversal.
Fully kinetic simulations of electron-scale plasma turbulence in the inner heliosphere: a pathfinder for future spacecraft missions
Authors: Franci Luca , Papini Emanuele , Micera Alfredo , Del Sarto Daniele , Lapenta Giovanni , Burgess David , Landi Simone
Published: March 2021

We present numerical results from high-resolution fully kinetic simulations of plasma turbulence under the near-Sun conditions encountered by Parker Solar Probe during its first perihelion, characterized by a low plasma beta and a large level of turbulent fluctuations. The recovered spectral properties are in agreement with those from PSP observations and recent high-resolution hybrid simulations just below the ion characteristic scales, i.e., the spectrum of the magnetic field exhibits a steep transition region with a spectral index compatible with -11/3. When the electron scales are reached a spectral break is observed and the spectrum steepens while still showing a clear power law. We discuss theoretical predictions for such a spectral behavior, based on a two-fluid model which assumes that a self-similar energy transfer across scales is occurring, without the need to include any kinetic process. We also analyse the role of magnetic reconnection and the statistics of reconnection events, as well as signatures in the proton and electron distribution functions hinting at mechanisms for energy dissipation. The results of this work represent a step forward in understanding the processes responsible for particle heating and acceleration and therefore on the origin of the solar wind and coronal heating. Furthermore, they allow for reliable predictions for future spacecraft missions investigating electron-scale physics in low-beta plasmas.
Crustal Characterization of Portugal's mainland based on Magnetotelluric measurements. 
Authors: Baltazar-Soares Pedro , Martinez Moreno Francisco , Alves Ribeiro Joana , Monteiro Santos Fernando , Pais Maria Alexandra , Ribeiro Paulo
Published: March 2021

In the last decades, the phenomena of Geomagnetic Induced Currents (GICs) have received special attention as one of the main hazards of Space Weather and has been widely investigated. In the high and mid-latitudes, these large GICs can flow in power systems and become problematic and even severe enough to cause a complete system shutdown. Two major factors determine GICs: (1) the strength and orientation of the electric field in the power system, which depends on the ionospheric and magnetospheric currents as well as on the crust and mantle conductivity; and (2) the electric power network characteristics. The Earth's conductivity can be obtained based on geophysical measurements that give the distribution of the conductivity in-depth and laterally. A realistic model of conductivity can be built based on the interpretation of Magnetotelluric (MT) soundings. The power of this geophysical method resides in the fact that it uses a natural source of energy, which allows estimating the conductivity distribution from a dozen of meters to some kilometres in depth.

We present a 3D resistivity model of the entire Portugal mainland based on more than 40 broadband MT soundings spaced 50x50km. The present study aims to contribute to a better understanding of Portugal's crust and its main geological structures. As a more practical application, knowledge of the presence of resistivity/conductivity bodies is important to obtain more precise GICs estimations. 

 
Safe Navigation and Visual Odometry-based Localization for Planetary Exploration Rovers 
Authors: Andolfo Simone , Gargiulo Anna Maria , Petricca Flavio , di Stefano Ivan , Genova Antonio
Published: March 2021

The future robotic exploration of planetary surfaces will require autonomous and safe operations to accomplish outstanding scientific objectives. The main goal of space robotic systems consists in expanding our access capability to harsh environments in the solar system (e.g., Martian polar caps, icy moons). However, the operations of systems onboard landers and rovers are still mainly commanded and controlled by ground operators. To enhance the efficiency of future rovers, we are developing a robust guidance, navigation and control system that enables safe mobility on different terrain and slopes conditions, including the presence of obstacles.

High slippery terrains, such as sandy-loose soils, could prevent the rover locomotion, affecting its safety. Furthermore, the presence of these demanding terrains may impact on the rover navigation, leading to inaccuracies in the Wheel Odometry (WO) measurements because of wheels’ loss of traction. Therefore, we implemented a navigation algorithm based on Visual Odometry (VO) that is the technique based on the processing of stereo-camera images captured at successive times during the vehicle’s motion. This method is fundamental to help WO during operations that require fast responses and high-accurate positioning. We also adopted a LIDAR sensor to improve the position estimate accuracy by processing measurements associated with well-known terrain features.

We present here numerical simulations of rover navigation across different terrain conditions by using accurate dynamical models, including the deformability of both wheel and terrain. VO and LIDAR data are simulated and processed to determine the positioning accuracies that enable safe navigation. The results are in full agreement with the existing (i.e., Mars Exploration Rovers (MER)) and future (i.e., ExoMars) rover performances. Our algorithm allows reconstructing the rover trajectory with higher accuracies compared to the localization system requirement of the NASA MER rovers (i.e., 10% error over 100 meters traverse).
Using Compressibility and Electric Field to Characterize Circularly-Polarized Waves Near the Proton Cyclotron Frequency Observed by Solar Orbiter
Authors: Khotyaintsev Yuri , Graham Daniel B , Steinvall Konrad , Vaivads Andris , Maksimovic Milan , Edberg Niklas J. T. , Johansson Erik P.G. , Eriksson Anders I. ,   RPW, MAG and SWA Teams
Published: March 2021

We report Solar Orbiter observations of electromagnetic waves near the proton cyclotron frequency during the first perihelion. The waves have polarization close to circular and have wave vectors closely aligned with the background magnetic field. Such waves are potentially important for heating of the solar wind as their frequency and polarization allows effective energy exchange with solar wind protons. The Radio and Plasma Waves (RPW) instrument provides a high-cadence measurement of plasma density and electric field which we use together with the magnetic field measured by MAG to characterize these waves. In particular we compute the compressibility and the phase between the density fluctuations and the parallel component of the magnetic field, and show that these have a distinct behavior for the waves compared to the Alfvénic turbulence. We compare the observations to multi-fluid plasma dispersion and identify the waves modes corresponding to the observed waves. We discuss the importance of the waves for solar wind heating.
New plant hydraulic architecture reproduces impacts of droughts in the Amazon rainforest
Authors: Papastefanou Phillip , Zang Christian , Pugh Thomas , Liu Daijun , Lapola David , Fleischer Katrin , Grams Thorsten , Hickler Thomas , Rammig Anja
Published: March 2021

The Amazon rainforest has been hit by extreme drought events in recent decades. Thereby, plant hydraulics are essential to better understand the impacts of droughts on single plants and whole forest ecosystems. Plant hydraulic mechanisms such as stomatal closure and leaf water potential are very complex, still posing challenges for current vegetation model development and parameterization. Here, we present the new hydraulic architecture of the Dynamic Global Vegetation Model LPJ-GUESS, accounting for leaf stomatal responses to plant water status and subsequent drought-induced mortality. We show that when applying the model to the Amazon rainforest we can reproduce the observed increasing trend in carbon losses and the decreasing trend in net carbon sink from plot observations over the past two decades. Our model simulations suggest that the increasing historical trend in carbon losses from mortality can be explained by hydraulic failure and associated mortality.

The high biodiversity of the Amazon tropical rainforest poses further challenges for process-based models. Here we present an approach to include the diversity of plant responses to drought by simulating 37 individual Plant Functional Types (PFTs) differing in their leaf water potential regulation- and resistance to soil water stress, and provide a simple solution how to cover a wide range of species and species-specific parameters. Future modelling studies should also take species interaction and competition of different hydraulic strategies into account.
Thermal modeling in active poly-phased calderas: case study of Los Humeros, Mexico 
Authors: Deb Paromita , Giordano Guido , Shi Xiangyun , Lucci Federico , Clauser Christoph , Calcagno Philippe
Published: March 2021

The Los Humeros Volcanic Complex (LHVC) is an active Quaternary caldera system in the Trans Mexican Volcanic Belt, characterized by two major caldera-forming events, Los Humeros (164 000 years ago) and Los Potreros (69 000 years ago). This site is also subjected to numerous episodes of post-caldera bi-modal volcanism during Holocene period (8 000 years – 3 000 years old). The volcanic complex hosts an active geothermal field which has been under commercial exploitation for the last 30 years. Latest geochemical, petrological and geochronological investigations consider the geothermal activity in the LHVC to be the result of an underlying complex magma plumbing system, characterized by numerous short-lived, shallow magma storage zones. Geothermal wells in the LHVC have encountered variable temperatures within depths of 2000 m, ranging from 170 °C at some areas to above 350 °C in the neighboring areas. To explain this anomalous temperature distribution and evaluate the thermal footprint of different volcanic episodes, we reconstructed the thermal history of the LHVC for a period of 182 000 years considering the spatially and temporally-varying nature of the heat sources. Our numerical model is constrained by information of depths, ages and volumes of the magma reservoirs, obtained from the geochemical and thermo-barometric modeling of the erupted material. The simulated present-day temperature state agrees well with the measured temperature data in the Los Humeros geothermal wells and can be used for identifying locations with anomalous temperature distribution. This integrated modeling approach, whereby numerical model is constrained by field-based geochemical information is essential in exploration geothermal fields, where limited borehole data is available, and promising for identifying potential locations of super-hot geothermal fluids.
Operational Aftershock Forecasting for 2017-2018 Seismic Sequence in Western Iran
Authors: Jalayer Fatemeh , Ebrahimian Hossein
Published: March 2021

On Sunday November 12, 2017, at 18:18:16 UTC, (21:48:16 local time), a strong earthquake with Mw7.3 occurred in western Iran in the border region between Iran and Iraq in vicinity of the Sarpol-e Zahab town. Unfortunately, this catastrophic seismic event caused 572 causalities, thousands of injured and vast amounts of damage to the buildings, houses and infrastructures in the epicentral area. The mainshock of this seismic sequence was felt in the entire western and central provinces of Iran and surrounding areas. The main event was preceded by a foreshock with magnitude 4.5 about 43 minutes before the mainshock that warned the local residence to leave their home and possibly reduced the number of human casualties. More than 2500 aftershocks with magnitude greater than 2.5 have been reported up to January 2019 with the largest registered aftershock of Mw6.4. A novel and fully-probabilistic procedure is adopted for providing spatio-temporal predictions of aftershock occurrence in a prescribed forecasting time interval (in the order of hours or days). The procedure aims at exploiting the information provided by the ongoing seismic sequence in quasi-real time. The versatility of the Bayesian inference is exploited to adaptively update the forecasts based on the incoming information as it becomes available. The aftershock clustering in space and time is modelled based on an Epidemic Type Aftershock Sequence (ETAS). One of the main novelties of the proposed procedure is that it considers the uncertainties in the aftershock occurrence model and its model parameters. This is done by moving within a framework of robust reliability assessment which enables the treatment of uncertainties in an integrated manner. Pairing up the Bayesian robust reliability framework and the suitable simulation schemes (Markov Chain Monte Carlo Simulation) provides the possibility of performing the whole forecasting procedure with minimum (or no) need of human interference. The fully simulation-based procedure is examined for both Bayesian model updating of ETAS spatio-temporal model and robust operational forecasting of the number of events of interest expected to happen in various time intervals after main events within the sequence. The seismicity is predicted within a confidence interval from the mean estimate.
Morphosedimentary and ecosystem evolution at Belharucas beach after a sand nourishment (Algarve, south Portugal)
Authors: Drago Teresa , Teixeira Sebastião , Rosa Marcos , Tuaty-Guerra Miriam , Gaudêncio Maria José , Lobo-Arteaga Jorge , Veronez Arthur , Taborda Rui , Cascalho João
Published: March 2021

Beach nourishment is an increasingly recommended solution for reversing the erosion process that affects nowadays the coastal zone. Usually, it is used in emergency situations as a local and short-term solution or as a regional and long-term management strategy.

From April 2017 to November 2019, sediment samples and beach profile data were collected seasonally, before and after a sand nourishment (100.000m3) that increased 30m of width in Belharucas beach (south Portugal, Algarve).

The main objective of the work was to evaluate the nourishment impact in the beach ecosystem, aiming at contributing to seafloor integrity assessment, in the scope of Descriptor 6 of the Marine Strategy Framework Directive. 

Methodology included grain size and macrobenthic fauna analyses in two profiles of the nourished area and another one further away, selected as a control area. Each profile was sampled at three intertidal zones: supralittoral (beach berm), mediolittoral (beach face) and infralittoral (low tide terrace).  Beach profile data were collected with the main objective of measuring the beach width and evaluate nourishment longevity.

Results show that grain size variability, higher at beach face, is dominated by local energy beach conditions rather than to changes related to the nourishment.

Morphological data shows that beach nourishment had a relatively low longevity as two years after the nourished beach present roughly the same width as priori to nourishment.

While supralittoral samples were defaunated, medio and infralittoral ones exhibited extremely low diversity. Assemblages were dominated by small-size polychaetes, bivalves and isopods. No statistically significant differences were found in assemblage composition regarding pre- and post-sand nourishment, year seasons, tidal zones and control stations.

In conclusion, Belharucas beach exhibited high resilience to the sand nourishment, preserving its morphodynamics and ecosystem conditions.

 

The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL and through the strategic project UIDB/MAR/04292/2019 - MARE and ECOEXA project (MAR-01.04.02-FEAMP-0016)
MCA-Unet: Multi-class Attention-aware U-net for Seismic Phase Picking
Authors: Li Wei , Rümpker Georg , Stöcker Horst , Chakraborty Megha , Fener Darius , Srivastava Nishtha
Published: March 2021

This study presents a deep learning based algorithm for seismic event detection and simultaneous phase picking in seismic waveforms. U-net structure-based solutions which consists of a contracting path (encoder) to capture feature information and a symmetric expanding path (decoder) that enables precise localization, have proven to be effective in phase picking. The network architecture of these U-net models mainly comprise of 1D CNN, Bi- & Uni-directional LSTM, transformers and self-attentive layers. Althought, these networks have proven to be a good solution, they may not fully harness the information extracted from multi-scales.

 In this study, we propose a simple yet powerful deep learning architecture by combining multi-class with attention mechanism, named MCA-Unet, for phase picking.  Specially, we treat the phase picking as an image segmentation problem, and incorporate the attention mechanism into the U-net structure to efficiently deal with the features extracted at different levels with the goal to improve the performance on the seismic phase picking. Our neural network is based on an encoder-decoder architecture composed of 1D convolutions, pooling layers, deconvolutions and multi-attention layers. This architecture is applied and tested to a field seismic dataset (e.g. Wenchuan Earthquake Aftershocks Classification Dataset) to check its performance.
Microplastics pollution in North and South Atlantic Ocean surface waters 
Authors: Pakhomova Svetlana , Yakushev Evgeny
Published: March 2021

Contamination of the World Ocean by synthetic non-biodegradable material has become a high profile environmental concern. Standardized sampling methods and methods of plastic identification should be developed so that results can be fed into international monitoring strategies to map plastic distribution worldwide. Here we present results of studies carried out on a transect between Tromsø and Svalbard and from Montevideo to Antarctica performed with the same sampling procedure onboard Norwegian and Russian ships in 08.2019 and 01.2020 respectively. Microplastic sampling was carried out using a filtering system. Water passed through the system and SPM was collected on a metal mesh screens. All potential plastic particles and fibers were checked for polymeric identification using a PerkinElmer Spotlight ATR-FTIR. The level of confirmed microplastics ranged from 0 to 1.9 items/m3 (0.7 items/m3 in average) on a transect Tromsø-Svalbard and from 0 to 2.5 items/m3 (0.4 items/m3 in average) on Montevideo-Antarctica transect. Both data sets were represented by 40% of fragments and 60% of fibers. Polyester was found as the main polymer type for both transects, 46% of microplastics. Other found polymer types were different in the North and South Atlantic Ocean waters. Nylon (polyamide) was the next most common polymer type in South Atlantic which was not found in Northern part. Difference was also observed in higher number of stations without any microplastics in South Atlantic.

This work was partly funded by the Norwegian Ministry of Climate and Environment project RUS-19/0001 “Establish regional capacity to measure and model the distribution and input of microplastics to the Barents Sea from rivers and currents (ESCIMO)” and the Russian Foundation for Basic Research, research projects 19-55-80004.
Monitoring land subsidence and element at risk in the Po Delta area (Northern Italy) through MT-InSAR and GNSS surveys
Authors: Chen Xue , Achilli Vladimiro , Cenni Nicola , Fabris Massimo , Menin Andrea , Monego Michele , Floris Mario
Published: March 2021

Delta areas are more likely to suffer from land subsidence due to tectonic and geological processes. Po Delta evolution shows a succession and superposition of complex processes caused by both natural and anthropogenic factors. The factors include sediment loading and compaction, post-glacial rebound, coastal flooding and erosion, sea level rise, land use changes, underground resources exploitation, population growth and urbanization. The natural subsidence has been estimated in the order of millimeters per year and the anthropogenic subsidence is greater than 10 mm/year. Several areas are located under the mean sea level and are exposed to flooding. These areas have been protected by embankments which represent a crucial element for flood risk mitigation. Multi-temporal interferometric synthetic aperture radar (MT-InSAR) and global navigation satellite system (GNSS) allow the continuous monitoring of land subsidence and structures and infrastructures deformations. The Po Delta landscape is characterized by large mudflats, farmland, and wetlands, and a low level of urbanization. Interferometry survey is difficult in this area, due to the temporal decorrelation caused by variations of the scattering properties associated with soil moisture and volume scattering, especially in the case of summer acquisitions. Then, MT-InSAR has to be integrated with ground-based measurements techniques which are costly and time consuming. In this study, MT-InSAR and GNSS techniques are combined to monitor the land subsidence and the deformations of the elements at risk, in particular the flood protection infrastructures. C-band Sentinel-1 and X-band COSMO-SkyMed SAR data acquired in 2014-2020 and 2012-2020, respectively, are considered. An MT-InSAR technique is exploited using the interferometric point target analysis (IPTA) method, making a network of targets including both distributed scatterers (DS) and persistent scatterers (PS). GNSS data have been collected by 3 permanent stations and 46 non-permanent stations (NPS) distributed in the Po Delta. The NPS were measured during three survey campaigns in 2016, 2018, and 2020. Results from MT-InSAR applied to Sentinel-1 data and GNSS techniques are compared and integrated to estimate the subsidence rates for most of the area. The monitoring of the embankments is possible using COSMO-SkyMed data due to their high resolution and high backscatter on structures and infrastructures. For future studies, the regression analysis between the natural/anthropogenic processing and the land subsidence of the Po Delta area can be performed to identify the major driving factors of the deformations in the different periods, which can improve the risk mitigation strategies.
Thin current sheets and the associated wave activity observed by Solar Orbiter
Authors: Graham Daniel , Khotyaintsev Yuri , Steinvall Konrad , Vaivads Andris , Maksimovic Milan , Edberg Niklas , Johansson Erik , Eriksson Anders , Kretzschmar Matthieu , Chust Thomas ,   RPW, MAG and SWA Solar Orbiter teams
Published: March 2021

Thin current sheets are routinely observed in the solar wind. Here we report observations of thin current sheets and the associated plasma waves using the Solar Orbiter spacecraft. The Radio and Plasma Waves (RPW) instrument provides high-resolution measurements of the electric field, number density perturbations, and magnetic field fluctuations, which we use to identify and characterise the observed waves, while the magnetic field provided by the MAG instrument is used to characterise the current sheets. We discuss the role of current sheets in the generation of the observed waves and the effects of the waves on the current sheets. 
Satellite-based characterization of methane point sources in the Permian Basin
Authors: Irakulis-Loitxate Itziar , Guanter Luis , Liu Yin-Nian , Varon Daniel J. , Maasakkers Joannes D. , Zhang Yuzhong , Chulakadabba Apisada , Wofsy Steven C. , Thorpe Andrew K. , Duren Riley M. , Frankenberg Christian , Lyon David , Cusworth Daniel H. , Zhang Yongguang , Segl Karl , Gorroño Javier , Sánchez-García Elena , Sulprizio Melissa P. , Aben Ilse , Jacob Daniel J.
Published: March 2021

The Permian Basin is known for its extensive oil and gas production, which has increased rapidly in recent years becoming the largest producing basin in the United States. It is also responsible for almost half of the methane emissions from all oil and gas producing regions in the country. Given the urgent need to reduce greenhouse gas emissions, it is crucial to identify and characterize the point sources of emissions. To this end, we have combined three new high-resolution hyperspectral sensors data onboard the GF-5, ZY1 and PRIMA satellites to create the first regional study to identify methane sources and measure the emitted quantities from each source. With data collected over several days in 2019 and 2020, we have identified a total of 37 point source emissions with flux rates >500kg/h, that is, a high concentration of extreme emission point sources that account for nearly 40% of the Permian annual emissions. Also, we have found that new infrastructure (post-2018) is responsible for almost 60% of the detected emissions, in many cases (21% of the cases) due to inefficient use of flaring of the gas that they cannot store. With this study, we demonstrate that hyperspectral satellite data are a powerful tool for the detection and quantification of strong methane point emissions.
Application of close-range remote sensing techniques for assessing landslide hazard in rock-carved cultural heritage sites
Authors: Frodella William , Elashvili Mikheil , Spizzichino Daniele , Gigli Giovanni , Nadaraia Akaki , Giorgi Kirkitadze Giorgi , Adikashvili Luka , Margottini Claudio , Antidze Nikoloz , Casagli Nicola
Published: March 2021

Rock-carved cultural heritage sites are often carved in slopes formed by weak rocks, which due to their peculiar lithological, geotechnical and morpho-structural features are often prone to weathering, deterioration and slope instability issues. In this context the use of advanced close-range remote sensing (RS) techniques, such as Infrared Thermography (IRT) and Unmanned Aerial vehicle-based Digital Photogrammetry (UAV-DP) can be profitably used for the rapid detection of conservation issues (e.g. open fractures, unstable ledges-niches, water seepage and moisture) that can lead to slope instability phenomena. These techniques when combined with traditional methods (e.g. field surveys, laboratory analysis), can provide fundamental data to implement a specific site-specific and inter-disciplinary approach for the sustainable protection and conservation strategies of Rock-carved cultural heritage sites. In this paper some examples of conservation problems in several rupestrian sites characterized by different geological contexts, from the mountainous regions of Georgia to the ancient city of Petra in Jordan, are presented, with the aim of evaluating the potential of the proposed approach integrated approach. The final aim is to provide conservators, practitioners and local authorities with a useful versatile and low-cost methodology, to be profitably used in management plans of rock carved sites.
Evaluating Dissolved Organic Carbon Retrieval in the Lena River Delta using Sentinel 3 OLCI Data
Authors: Preusker Rene , El Kassar Jan , Juhls Bennet
Published: March 2021

As air temperatures in the Arctic continue to rise, permafrost thaw intensifies, and discharge from the Arctic rivers increases. These drastic changes are likely to accelerate mobilization of organic matter and its export through rivers into the Arctic Ocean. Therefore, thorough monitoring of these processes becomes increasingly important. The Lena River with its large catchment area is one of the major sources of the organic carbon in the Arctic Ocean and, therefore, plays a crucial role in the Arctic carbon cycle. 
To observe current and future changes of carbon transport via the Lena River, a new monitoring program has been initiated in 2018. In situ water samples are collected from the one of the Lena Delta branches every several days. Since generally the in situ sampling in the Arctic is challenging and costly, in this study, we test the potential of remote sensing to complement the field observations. Remote sensing provides synoptic spatial coverages and high temporal resolution at high latitudes. 
We test the retrieval of dissolved organic carbon (DOC) from satellite-derived chromophoric dissolved organic matter (CDOM). For this, we use measurements of the Ocean & Land Colour Instrument (OLCI) on board the Sentinel-3 satellites in combination with beforehand tested atmospheric correction algorithms and CDOM retrieval algorithms. The quality of the satellite retrieved DOC of the Lena River water is assessed by DOC, measured in the in situ samples. Remotely sensed DOC contributes to an improvement of DOC fluxes monitoring, which can potentially be extended to all big Arctic rivers.
Search for oblique Whistler waves using solar orbiter data
Authors: Colomban Lucas , Kretzschmar Matthieu , Krasnoselskikh Volodya , Bercic Laura , Owen Chris , Maksimovic Milan
Published: March 2021

Whistler waves are thought to play an important role on the evolution of the electron distribution function as a function of distance. In particular, oblique whistler waves may diffuse the Strahl electrons  into the halo population.  Using AC magnetic field from the RPW/SCM (search coil magnetometer) of Solar Orbiter, we search for the presence of oblique Whistler waves in the frequency range between 3 Hz and 128 Hz .  We perform a minimum variance analysis of the SCM data in combination with the MAG (magnetometer) data to determine the inclination of the waves with respect to the ambiant magnetic field. As the emphasis is placed on the search for oblique whistler, we also analyze the RPW electric field data and the evolution of the electron distribution function during these Whistler events.
Optimized operation of a multireservoir system by means of Recurrent Neural Networks for inflow forecasting
Authors: Müller Tim , Meon Günter
Published: March 2021

The operation optimization of interconnected reservoirs is crucial for effective water resources management. Therefore, a decision support tool for is developed based on the forecasts of natural inflows. Standard forecast procedures are often based on historical streamflows and hydrological modelling of flows using quantitative meteorological forecasts. In recent years, forecasting using deep learning methods and especially recurrent neural networks have gained attention. Compared to other approaches such as regression-based and time series models, artificial neural networks have proven to be more effective and flexible. We propose a long short-term memory network (LSTM) for forecasting inflow into reservoirs with a large watershed. It is trained with observed hourly streamflow and meteorological data and applicable to different forecast horizons. The novelty here is the inclusion of temperature, windspeed and snow into the forecast.

The Drin river cascade (11 830 km²) in Northern Albania was selected as a pilot hydraulic system, whereby the upper part of the Drin river basin covers also parts of North Macedonia, Kosovo and Montenegro. The cascade consists of three large dams in series. The reservoirs are primarily used for energy generation and, secondarily, for flood retention. The studied LSTM forecast horizons (6, 8, 12 hours; >12 hours) indicate that the Recurrent Neural Network provides a proper forecast of the natural inflows into the reservoir cascade and thus represents a valuable tool for the optimization of the operation of the Drin Cascade under multi-criteria conditions.