bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical modelling of tsunamis generated by mass flows at Stromboli Volcano
Authors: Manzella Irene , Makris Symeon , Di Traglia Federico , Kelfoun Karim , Cole Paul , Casalbore Daniele , Chiocci Francesco L
Published: March 2021

As demonstrated by the Anak Krakatau eruption-induced flank collapse in 2018 in Indonesia, tsunamis generated by large mass flows like landslides and pyroclastic density currents can have devastating effects in volcanic areas. However, these phenomena are still poorly understood as they are unusual and complex events, largely unpredictable and often poorly constrained. 

Stromboli is one of the most active volcanoes in the world, extensively monitored and studied in the last few decades. Many tsunamigenic landslides (sub-aerial and/or submarine) have taken place; at least seven have occurred in the last 150 years and a devastating one is believed to have reached the coast of Naples, at more than 200 km distance, during the Middle Ages. Because the level of activity of the volcano has remained similar ever since and the likelihood of such disastrous events is not negligible, the hazard related to tsunamigenic mass flows in this area needs to be carefully assessed.

Associated with the 3rd of July 2019 eruption, at least three mass flows were triggered along the Sciara del Fuoco slope; two subaerial Pyroclastic density currents (PDCs) and a submarine landslide. Simultaneously, three buoys registered the height of the resulting tsunami wave ranging from 0.2 m in front of the Ginostra village to 1.5 m in front of the Sciara del Fuoco. Thanks to the dense monitoring network and the accurate bathymetry survey carried out by the IGAG-CNR, these events have been well constrained. 

The tsunami waves studied here are smaller than those that could constitute a threat for the population living in this area, nevertheless they can be used to characterize the behaviour of the tsunamigenic mass flows. Back analysis of these events were undertaken with the two-fluids version of VolcFlow; this is a continuum mechanics model based on the depth-average approximation that has been developed for the simulation of volcanic flows. VolcFlow can take into account several different rheologies for each of the two fluids. In the present case, one fluid was used for the water body and one for simulating the mass flow. For the latter one, a constant retaining stress type of rheology was used (Dade and Huppert, 1998). Backanalysis suggested that it was the PDC which generated the tsunami wave during the events of July 2019 and best fitting simulations identified a constant retaining stress of 7kPa. With these input parameters it has been possible to run a large number of numerical simulations of possible scenarios. This has allowed to assess threshold values of volume and discharge of mass flows which could generate significant and potentially destructive tsunami waves. This constitutes an important input to improve early warning systems and to reduce the risk related to these unpredictable but extremely dangerous phenomena.
The Effect of Cyclic Loading of Liquefaction on Palu Sands 
Authors: Andanawarih Muhammad Firas , Prakoso Widjojo Adi
Published: March 2021

Liquefaction is a phenomenon where soil loses its strength. The phenomenon of liquefaction occurs on non-cohesive soils with medium to fine grains. The phenomenon of liquefaction occurs during an earthquake, the ground experiences shaking vibrations. Palu, Central Sulawesi, Indonesia is one of the areas affected by the liquefaction phenomenon which causes damage to infrastructure in the area. The Palu earthquake that occurred on September 28, 2018, at 18:02:44 WITA with a magnitude of Mw = 7.4, centered on 26 km north of Donggala, Central Sulawesi. One aspect of the assessment for soil susceptibility to potential liquefaction is laboratory tests. One common laboratory test that can be performed is the cyclic triaxial test. The factors affecting the liquefaction resistance of saturated sand are the relative density and cyclic stress ratio (CSR). The susceptibility of each relative density (30%, 50% and 70%) of the soil experiencing liquefaction and the cyclic stress ratio (0.15, 0.20 and 0.25) will be varied to see the amount of cyclic load needed until the soil experiences liquefaction, the load frequency to represent the earthquake load is 1 Hz with sinusoidal waves. This study will test the fine sands from Palu, Central Sulawesi, Indonesia, to determine their respective behavior when the soil is given a cyclic load.

Keywords: Cyclic Triaxial, Liquefaction, Cyclic Stress Ratio, Relative Density, Fine Sands.
Shot gun sequencing of sedimentary ancient DNA from an Arctic lake reveals ecosystem changes through climate regime transitions over the last 50,000 years 
Authors: Stoof-Leichsenring Kathleen R. , Huang Sichao , Pestryakova Luidmila A. , Biskaborn Boris K. , Herzschuh Ulrike
Published: March 2021

Sedimentary ancient DNA is a valuable proxy to study ecosystem change during the past. In particular, Arctic lakes provide fantastic archives of well-preserved DNA in lake sediment cores and provide reconstructions of ecosystem change during climate transitions in the past, which help to predict prospective environmental changes under current rapid warming known to be strongest in the Arctic. Our analyses are conducted on a 10 m sediment core from Lake Ilirney, located in Eastern Chukotka, which covers the last 50 ka of major climate transitions from the lake’s development within a warmer period previous to the last glacial towards nowadays. We prepared seventeen single-stranded DNA libraries from different time slices and used shot gun sequencing, an innovative method neglecting target enrichment, to achieve a portray of the past biotic composition. The bioinformatic data analyses included data trimming and merging with Fastp and k-mer based taxonomic classification against the nucleotide database using Kraken2. Preliminary results revealed about 372 bacterial families (about 90.1% of total reads), 651 eukaryotic families (8.7%) and a few Archaea (1.1%). Dominant eukaryotic groups are plants (Saliceae, Poaceae, and Rosaceae), protists (Monodopsidaceae, Oomycota and flagellates), fish (Salmonidae, Cyprinidae), birds (Phasianidae) and mammals (Muridae). Our data confirms compositional changes of plants throughout the last 28 ka known from pollen and metabarcoding analyses of a parallel core. Further, our data revealed most prominent turnover of the eukaryotic key taxa at about 30 and 12 ka which corresponds to the major climatic transitions from glacial-interglacial periods. The detailed investigation of compositional patterns and authenticity of ancient DNA data will improve our understanding of ecosystem change in the Arctic over millennial time scales.
Equality, Diversity, and Inclusion in Geoscience (EDIG) initiative: A time to listen, learn, and act.
Authors: Doran Aileen , Bidgood Anna , Blowick Aoife , Craig Jennifer , Ekandjo Halleluya , Fox Arron , Foxe Jana , Franklin Jess , Hitzman Murray , McAuliffe Fergus , Neofitu Roland , Torremans Koen , Twigg Helen , Wallace Elspeth
Published: March 2021

The Equality, Diversity, and Inclusion in Geoscience (EDIG) initiative was created to better understand the experiences of the geoscience community with respect to prejudice, inequity, bias, exclusion, sexism, and discrimination. EDIG aims to provide a platform for learning for the wider geoscience community and promote progressive action to make geoscience more inclusive and equitable.

As part of our initiatives, we organised the virtual EDIG conference in December 2020 entitled: A time to listen, learn, and act. This virtual event aimed to facilitate learning on equality, diversity, and inclusion related topics relevant to the geosciences. It hosted sessions on where we have come from, where we are now, and where we are going. The conference especially focused on raising awareness around the challenges experienced by minoritized geoscientists, helping to involve more people in these conversations. The conference hosted 17 speakers on a range of different topics, from the history of diversity in geoscience, to how we can become more inclusive, to how we can move forward together, as well as a workshop on unconscious bias sponsored by the Institute of Geologists of Ireland (IGI) and the Irish Centre for Research in Applied Geology (iCRAG).

Prior to the EDIG conference, we launched a global survey to carry out research on equality, diversity, and inclusion in the geosciences. The survey asked people about their own experiences (or lack of) around EDI related topics. The survey received a large response, with 708 participants from 58 countries. The main themes from the survey data were used to structure our conference programme.

We will present the results of this survey, and our experiences of the EDIG conference. With these and future events we hope to bring together several online initiatives, establish a community of support and learning, and to help us all come together to make the geosciences more welcoming, accessible, inclusive, and equitable.
Data-driven estimate of past and present surface loading over North America: Bayesian Hierarchical Modelling approach applied to GPS and GRACE observations
Authors: Ziegler Yann , Vishwakarma Bramha Dutt , Brady Aoibheann , Chuter Stephen , Royston Sam , Westaway Richard , Bamber Jonathan
Published: March 2021

Glacial Isostatic Adjustment (GIA) and the hydrological cycle are both associated with mass changes, which are observed by GRACE, and vertical land motion (VLM), which is observed by GPS. Hydrology-related VLM results from the instantaneous response of the elastic solid Earth to surface loading by freshwater, whereas GIA-related VLM reveals the long-term response of the visco-elastic Earth mantle to past glacial cycles. Thus, observations of mass changes and VLM are interrelated and GIA and hydrology are difficult to investigate independently. Taking advantage of the differences in the spatio-temporal characteristics of the GIA and hydrology fields, we can separate the respective contributions of each process. In this work, we use a Bayesian Hierarchical Modelling (BHM) approach to provide a new data-driven estimate of GIA and time-evolving hydrology-related VLM for North America. We detail our processing strategy to prepare the input data for the BHM while preserving the content of the original observations. We discuss the separation of GIA and hydrology processes from a statistical and geophysical point of view. Finally, we assess the reliability of our estimates and compare our results to the latest GIA and hydrological models. Specifically, we compare our GIA solution to a forward-model global field, ICE-6G, and a recent GIA estimate developed for North America (Simon et al. 2017). Our time-evolving hydrology field is compared with WaterGAP, a global water balance model. Overall, for both GIA and hydrology, there is a good agreement between our results and the forward models, but we also find differences which possibly highlight deficiencies in these models.
A new approach to constrain the seismic origin for prehistoric turbidites as applied to the Dead Sea Basin
Authors: Hubert-Ferrari Aurelia , Moernaut Jasper , Bookman Revital , Waldmann Nicolas , Wetzler Nadav , Agnon Amotz , Marco Shmuel , Alsop G. Ian , Strasser Michael , Lu Yin
Published: March 2021

Seismogenic turbidites are widely used for geohazard assessment. The use of turbidites as an earthquake indicator requires a clear demonstration that an earthquake, rather than non-seismic factors, is the most plausible trigger. The seismic origin is normally verified either by correlating the turbidites to historic earthquakes, or by demonstrating synchronous deposition over large areas of a basin. Correlating historic earthquakes could potentially constrain the seismic intensities necessary for triggering turbidites, however this method is not applicable to prehistoric events. In addition, the synchronous deposition of turbidites cannot be verified for a single core record.

Here, we propose a new approach to establish the seismic origin of prehistoric turbidites that involves analyzing in situ deformation that underlies each turbidite, as recorded in a 457 m-long core from the Dead Sea depocenter. These in situ deformations have been previously verified as seismites and could thus authenticate the trigger for each overlying turbidite. We also constrain the seismic intensities that triggered prehistoric turbidites by analyzing the degree of in situ deformation underlying each turbidite. Moreover, our high-resolution chemical and sedimentological data validate a long-lasting hypothesis that soft-sediment deformation in the Dead Sea formed at the sediment-water interface. In addition, we use our results to propose seven basic earthquake-related depositional scenarios preserved in depocenters located in tectonically active regions like the Dead Sea. These techniques and findings permit a more confident geohazard assessment in the region and act as a model for other similar tectonic settings, by improving the completeness of a paleoseismic archive.
The future of the Sundarbans mangroves in India
Authors: Hazra Sugata , Samanta Sourav , Halder Ananya , Nicholls Robert , French Jon
Published: March 2021

The Sundarbans Biosphere Reserve is situated near Kolkata in the western part of the Ganges-Brahmaputra Delta. The Sundarbans mangroves together with the areas in Bangladesh are the world’s largest mangrove forest and home to the iconic Royal  Bengal Tiger. It is a Ramsar and World Heritage site. Over the last 20 years the mangroves have retreated from 10 to 50 m/yr along the open coast with the loss of 145 km2 area of the biosphere reserve , 40% of which constitute the  mangrove forest. This erosion reflects a response to waves in the Bay of Bengaland relative sea-level rise of about  5 mm/yr since 1948 which increased further during the last decade. In percentage terms this observed forest land loss is manageable. However, it will continue and almost certainly accelerate with sea-level rise. As well as open coast erosion, inundation will also occur within the mangroves. Hence over many decades,Sundarbans mangroves will be progressively degraded endangering  their iconic species. We are using these observed data and the Sea Level Affecting Marshes Model (SLAMM)to explore possible trajectories of the Sundarbans evolution under different sea-level rise scenarios and management interventions. The areas to the north are densely populated and increasingly influenced by the expansion of Kolkata. Discussions with stakeholders suggest a managed retreat does not seem feasible or practical due to the large displaced populations.The paper will discuss theinter linkages of the slow onset hazard in a sinking and shrinking delta to explore pathways to achieve sustainable outcomes in south Asian deltas.  
Thermal and mechanical characterization of a new material based on two gypsums from different localities : High Atlas of Marrakech and Safi Basin, Morocco
Authors: baba imane , Ibnoussina Mounsif , Witam Omar , Saadi Latifa
Published: March 2021

Over the last few decades, the construction industry has become interested in materials that are durable, environmentally friendly and easily recyclable. This interest is due to the advantages these materials offer, among others local availability, low carbon footprint, energy efficiency and indoor comfort. The objective of this work is to study the properties of plasters prepared from a mixture of two types of gypsum. We were interested in the evolution of thermal conductivity, mechanical resistance and setting time as a function of the percentage of addition.

Two types of gypsum were studied, the first one belongs to the Safi basin and the second one comes from the High Atlas of Marrakech.

The characterization of the gypsums was necessary to determine its physical and geotechnical properties, its mineralogy, its thermal behavior and its microscopic structure. Several analyses were developed such as density measurement by pycnometer, X-ray diffraction, infrared spectroscopy and scanning electron microscopy.

We have made samples, of standardized dimensions, of mixtures based on both types of plaster. The water/gypsum mass ratio was set at 0.75.

The results revealed that the properties of gypsum as well as the percentage of addition affect the mechanical and thermal properties and the setting time of the composite material. The addition of the High Atlas gypsum of Marrakech allowed improving the material in terms of thermal insulation. The results of the other tests will be communicated later.
Multi-Hazard Scenarios and Dynamic Risk
Authors: Gill Joel , Hussain Ekbal , Malamud Bruce , Šakić Trogrlić Robert
Published: March 2021

In this paper, we discuss the dynamic nature of risk through the lens of multi-hazard relationships and scenarios. Disaster risk is commonly expressed as (Risk = Hazard × Exposure × Vulnerability). This expression does not communicate the extent to which each term (and therefore risk and impact) can change over time, and any relationships between the four variables. To better convey and discuss multi-hazards and dynamic risk, in July and August 2020 we held two virtual workshops (40 and 35 participants) as part of the GCRF Tomorrow’s Cities Research Hub, which has as its focus four cities Istanbul, Kathmandu, Nairobi, and Quito, with a particular emphasis on the urban poor. During the two workshops, participants (including those from academia, NGOs, and the public sector) from each city generated multi-hazard scenarios that can be used to improve the understanding of dynamic risk and we highlighted three main examples of dynamic risk: (1) The hazard term can involve multiple hazards, with relationships between hazards, and the likelihood or magnitude of single natural hazards and multi-hazard scenarios varying over time. (2) Both the exposure and vulnerability components of the risk equation change over time, and can contribute to the triggering, amplification (or reduction) of multi-hazard events. (3) Progression through multi-hazard scenarios can influence or drive changes in both exposure and/or vulnerability terms. These three statements illustrate the dynamic nature of each component of the risk equation and the existence of relationships between each term. Furthermore, they demonstrate how understanding the multi-hazard landscape and potential multi-hazard scenarios can help to enrich understanding of dynamic risk. This understanding of multi-hazard scenarios can be used to consider potential interventions where risk is dynamic.
The Pacific Decadal Oscillation Modulates Tropical Cyclone days in the North Pacific Ocean
Authors: Scoccimarro Enrico , Villarini Gabriele , Gualdi Silvio , Navarra Antonio
Published: March 2021

Tropical cyclones (TCs) in the North Pacific Ocean claim a major socio-economic toll on a yearly basis, and their impacts are projected to be exacerbated due to climate change and increased exposure and vulnerability. Recent examples of Typhoons Mangkhut (2018) and Hagibis (2019) are a reminder of the devastating impacts these storms can have. While the TC activity in the West North Pacific (WNP) and East North Pacific (ENP)  has been the subject of intense investigation, these basins are generally treated separately, rather than considering the storm activity in the North Pacific as a single basin. The influence of climate processes, such as the Pacific Decadal Oscillation (PDO) ,  that operate across the entire North Pacific may not have been considered by focusing on the sub-basins, especially if we are interested in multi-annual and decadal changes. It is reasonable to hypothesize that a climate mode like the PDO could play an important role in terms of TC activity in this basin. However, there is limited evidence that connects these storms and the PDO. Our expectation is that the number of TC days is related to the PDO through the modulation of this climate mode of the SST in the regions where these storms develop. In particular, during the positive phase of the PDO, warm waters close to the equator would lead to conditions favorable to the development of longer-lasting storms compared to the negative PDO phase, which is characterized by lower SST values. We believe that this connection has not been sufficiently considered in the literature because the North Pacific Ocean was not considered as a single basin but broken up into WNP and ENP, confounding the detection of a potential PDO signal. Therefore, in this work we focus on the potential role of the PDO in modulating TC activity, with emphasis on the number of TC active days in the entire North Pacific Ocean. We have selected this metric because the number of TC days provides an integrated information about TC genesis, lifespan, and tracks, and because it exhibits substantial decadal-scale oscillations in TC activity compared to other metrics used to highlight TC activity. We aim to verify the effects of different SST patterns on the spatial distribution of TC genesis in the North Pacific leading to conditions that are more/less favorable for long-lasting TCs under positive/negative PDO phases. A larger number of TC days for storms that tend to develop along the tropics during the positive PDO phase is found. When we stratify the years according to the sign of the PDO phase, the years associated with the positive phase tend to have storms that form at a lower latitude and that last longer  compared with the negative phase. On average, these storms tend to form around 14°N and to result in 240 TC days; during the negative PDO phase, TCs tend to form around 16°N, for a total of 160 TC days.
Theoretical and practical aspects in determining the current geochemical status of the Crimean peninsula and anthropogenic risk to public health
Authors: Evstafeva Elena , Tymchenko Svetlana , Bogdanova Anna , Zalata Olga , Boyarinceva Yuliia , Moskovchuk Olga , Evstafeva Irina , Slusarenko Alexandra , Makarova Anna , Yaseneva Elena
Published: March 2021

The implementation of basic principles of medical and ecological monitoring programs in Crimea previously reported in EGU proceedings consists of determining the content of a wide range of toxic, essential and rare earth elements in various biological substrates: soil, plants, water, human body. Biosubstrates are sampled in different locations with contrast natural and anthropogenic conditions: urbanized-rural, industrial-agricultural, natural resources. Lichens and poplar leaves are used as indicators of environmental contamination, particularly atmospheric pollution; liquid precipitation is used as an indicator showing the negative impact of air pollution on ecosystems; hair is used as an indicator of the total body intake of chemical elements. The update of databases, on some of the territories (Simferopol, Sevastopol, geographical regions with different soil characteristics, etc.) with regard to some of the elements (mercury, lead, cadmium, selenium, etc.) at this stage allowed to determine their biogeochemical status in conditions of intensive growth of anthropogenic load in recent years, and to compare it with the elemental status of the humans living in this territory. The databases for other types of territories continue to be extended, the relationship between morbidity to estimate of the environmental burden of disease for environmentally determined diseases (neurodegenerative, endocrine, respiratory, etc.) and chemical load on the territories, based on USEtox model; the functional state of target systems (nervous, immune, cardiovascular) and level of chemical elements in the human body and the overall elemental imbalance, is established. This has provided us with a degree of understanding on how the degree of population and individual health risk could be determined.

Mercury analysis was funded by RFBR according to the research project № 18-29-24212\19 entitled “Development of neutralization of mercury-containing waste without heating and the formation of wastewater”, 2018–2021 years; elemental composition was possible to determine due to RFBR project № 18-45-920042\20 entitled “Bioecological monitoring of heavy metals at board of Black Sea of Crimea”, 2018–2020 years. Physiological part of research was possible to accomplish due to funds by the V.I. Vernadsky Crimean Federal University (Project No VG2019/15, АААА-А20-120012090158-7).
Investigating the NO-dependent photooxidation of limonene by OH and O3 using the atmosphere simulation chamber SAPHIR
Authors: Pang Yat Sing , Kaminski Martin , Novelli Anna , Carlsson Philip , Acir Ismail-Hakki , Bohn Birger , Cho Changmin , Dorn Hans-Peter , Hofzumahaus Andreas , Li Xin , Lutz Anna , Nehr Sascha , Reimer David , Rohrer Franz , Tillmann Ralf , Wegener Robert , Kiendler-Scharr Astrid , Wahner Andreas , Fuchs Hendrik
Published: March 2021

Limonene is the fourth-most abundant monoterpene in the atmosphere, which upon oxidation leads to the formation of secondary organic aerosol (SOA) and thereby influences climate and air quality.

In this study, the oxidation of limonene by OH at different atmospherically relevant NO and HO2 levels (NO: 0.1 – 10 ppb; HO2: 20 ppt) was investigated in simulation experiments in the SAPHIR chamber at Forschungszentrum Jülich. The analysis focuses on comparing measured radical concentrations (RO2, HO2, OH) and OH reactivity (kOH) with modeled values calculated using the Master Chemical Mechanism (MCM) version 3.3.1.

At high and medium NO concentrations, RO2 is expected to quickly react with NO. An HO2 radical is produced during the process that can be converted back to an OH radical by another reaction with NO. Consistently, for experiments conducted at medium NO levels (~0.5 ppb, RO2 lifetime ~10 s), simulated RO2, HO2, and OH agree with observations within the measurement uncertainties, if the OH reactivity of oxidation products is correctly described.

At lower NO concentrations, the regeneration of HO2 in the RO2 + NO reaction is slow and the reaction of RO2 with HO2 gains importance in forming peroxides. However, simulation results show a large discrepancy between calculated radical concentrations and measurements at low NO levels (<0.1 ppb, RO2 lifetime ~ 100 s). Simulated RO2 concentrations are found to be overestimated by a factor of three; simulated HO2 concentrations are underestimated by 50 %; simulated OH concentrations are underestimated by about 35%, even if kOH is correctly described. This suggests that there could be additional RO2 reaction pathways that regenerate HO2 and OH radicals become important, but they are not taken into account in the MCM model.
τeκτoniκa, a journal for an open future
Authors: Gouiza Mohamed , Fernández Blanco David , Bond Clare , McCarthy Dave , Lee Amicia , Pérez-Díaz Lucia , community τeκτoniκa
Published: March 2021

τeκτoniκa is an up-coming community-led diamond open access (DOA) journal, which aims to publish high-quality research in structural geology and tectonics. It is a grass-roots community-driven initiative that relies on the involvement of Earth Scientists from around the globe; that together represent the wide and diverse spectrum of the structural geology and tectonics community. 

Beyond the obvious objective of publishing novel research on structural geology and tectonics, it is intended to offer an alternative to traditional publishing models, which hide scholarly work behind exclusive and expensive paywalls. τeκτoniκa is a new addition to the growing set of DOA journals that have appeared in recent years. Along with preprint platforms, data and software repositories, it is part of an expanding movement within academia focused on breaking the barriers inherited from the pre-internet publishing era, to ensure free and open access to knowledge.

This contribution aims to showcase the value of this ambitious project as well as our vision for how DOA journals in general (and Tektonika in particular) might shape the future of geoscience publishing.
Sentinel-2 exposed soil composite for soil organic carbon prediction: the ‘greening-up’ method for detecting suitable images
Authors: Dvorakova Klara , van Wesemael Bas
Published: March 2021

Pilot studies have demonstrated the potential for remote sensing techniques for soil organic carbon  (SOC) mapping in exposed croplands. However, the use of remote sensing for SOC prediction is often hindered by disturbing factors at the soil surface such as photosynthetic active and nonphotosynthetic active vegetation, variation in soil moisture or surface roughness. With the increasing amount of freely available satellite data, many studies have focused on stabilizing the soil reflectance by building image composites that are generated using a set of criteria. These composites tend to minimize and cancel out the disturbing effects. Here we aim to develop a robust method that allows selecting Sentinel-2 (S-2) pixels that are not affected by the following disturbing factors: crop residues, surface roughness and soil moisture. We selected all S-2 cloud-free images covering the Loam Belt of Belgium from January 2019 to December 2020 (in total 38 images). We then built four exposed soil composites based on four sets of criteria: (1) NDVI < 0.25, (2) NDVI < 0.25 & Normalized Burn Ratio (NBR2) < 0.07, (3) the ‘greening-up’ period of a crop and (4) the ‘greening-up’ period of a crop & NBR2 < 0.07. The ‘greening-up’ period was selected based on the NDVI timeline, where ‘greening-up’ is considered as the last date of acquisition where the soil is bare (NDVI < 0.25) before the crop develops (NDVI > 0.6).,We then built a partial least square regression (PLSR) model with 10-fold cross-validation to estimate the SOC content based on 137 georeferenced calibration samples on the four above described composites. We obtained a non-satisfactory result for composites (1) to (3): R² = 0.22, RMSE = 3.46 g C kg-1 and RPD 1.12 for (1), R² = 0.19, RMSE = 3.43 g C kg-1 and RPD 1.10 for (2) and R² = 0.15, RMSE = 2.74 g C kg-1 and RPD 1.06 for (3). We, however, obtained a satisfactory result for composite (4): R² = 0.54, RMSE = 2.09 g C kg-1 and RPD 1.68. Hence, the ‘greening-up’ method combined with a strict NBR2 threshold allows selecting the purest exposed soil pixels suitable for SOC prediction. The limit of this method might be the surface coverage, which for a two-year period reached 47% of croplands, compared to 89% exposure if only the NDVI threshold is applied.
Fault parameters of the Mw 6.4 January 7, 2020, Puerto Rico earthquake estimated from teleseismic, GNSS and InSAR data
Authors: Nobile Adriano , Viltres Renier , Vasyura-Bathke Hannes , Trippanera Daniele , Wenbin Xu Wenbin , Passarelli Luigi , Jónsson Sigurjón
Published: March 2021

We used teleseismic waveforms and ground deformation data from GNSS and InSAR to estimate source fault parameters of the Mw6.4 earthquake that occurred just offshore southwestern Puerto Rico on 7 January 2020. The mainshock was a part of an energetic seismic sequence that started on 28 December 2019 and led to a Mw5.8 earthquake on 6 January 2020, a day before the Mw6.4 mainshock. The ground-shaking due to the largest earthquakes of the sequence caused significant damage to buildings and infrastructures in Puerto Rico and one casualty was reported by the local media. The mainshock was followed by a strong aftershock sequence that included four Mw ≥ 5 events within the first 3 hours. In the first 40 days of the seismic sequence, data from the Puerto Rico Seismic Network were used to locate ~3800 earthquakes of magnitude > 2, illuminating an east-west elongated 30x50 km2 area, just offshore the southwestern coast of Puerto Rico. The region affected by this activity was before characterized by relatively low seismicity rates, even if a system of active faults, both onshore and offshore, had been mapped. The sequence is peculiar due to its complex development and many large aftershocks (magnitude > 4.5), with the mainshock releasing only  ~60% of the total seismic moment.

We estimated the key source parameters of the mainshock using teleseismic data, GNSS data from the Puerto Rico Geodetic Network, and InSAR data from the Sentinel-1 and ALOS-2 satellites. The modeled source is consistent with a ~15 km long and ~11 km wide blind fault, oriented roughly east-west and dipping 46o towards north, and with up to 1.1 m of oblique normal and left-lateral strike-slip.

The optimal fault plane source indicates that it is an offshore continuation of the mapped North Boquerón Bay - Punta Montalva fault zone, supported by the large number of the aftershocks that trend along the same direction. However, most of the aftershocks, even those of magnitude > 5, occurred on other nearby faults, highlighting the complexity of this fault zone area.
Observations of surface heat and moisture exchange in the marginal sea ice and implications for model parameterization
Authors: Elvidge Andrew , Renfrew Ian , Brooks Ian , Srivastava Piyush , Yelland Margaret , Prytherch John
Published: March 2021

Aircraft observations from two Arctic field campaigns are used to derive ice surface characteristics and make recommendations for the parametrisation of surface heat and moisture exchange over sea ice and the marginal ice zone (MIZ). The observations were gathered in the Barents Sea and Fram Strait as part of the Aerosol–Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) project, and off the south-east coast of Greenland as part of the Iceland-Greenland Seas Project (IGP). Estimates of roughness lengths for momentum (z0), heat (z0T) and moisture (z0q) are derived from turbulent wind velocity, temperature and humidity measurements; while sea ice concentration is derived from albedo measurements. The two data sets cover a range of sea ice characteristics, being much rougher in general during IGP than during ACCACIA. Large fluxes of heat and moisture were observed in the vicinity of the MIZ during both field campaigns. We show that z0T and z0q over 100 % sea ice (z0Ti and z0qi) vary as a function of a roughness Reynolds number (R*; which itself is a function of z0 and wind stress), with a peak at the transition between the aerodynamically smooth (R*<0.135) and aerodynamically rough (R*>2.5) regimes. One of the few theory-based parameterisations available for z0Ti and z0qi (that of Andreas et al., 1987) reproduces these peaks, in contrast to the simple treatments currently employed in two leading numerical weather and climate prediction models – the Met Office Unified Model (MetUM) and the Integrated Forecast System (IFS) – which do not. The MetUM and IFS schemes perform adequately in smooth conditions, but greatly overestimate heat and moisture exchange in rough conditions. We develop a new parameterisation for heat and moisture exchange as a function of sea ice concentration, which blends the Andreas et al. (1987) scheme over sea ice with exchange over the ocean. This new parameterisation performs much better than the current MetUM and IFS schemes for the rough conditions observed during IGP, at least halving the bias and root-mean-square errors in sensible and latent heat fluxes; and is also marginally better for the comparatively smooth conditions observed during ACCACIA, suggesting further evaluation is warranted. However, it should be noted that representing heat and moisture exchange over sea ice is currently limited by the variability in z0 over 100 % sea ice, which is unrepresented in weather and climate models.
Mapping landslides using drone's full-motion videos
Authors: Sandric Ionut Cosmin , Ilinca Viorel , Irimia Radu , Chitu Zenaida , Jurchescu Marta , Plesoianu Alin
Published: March 2021

Rapid mapping of landslides plays an important role in both science and emergency management communities. It helps people to take the appropriate decisions in quasi-real-time and to diminish losses. With the increasing advancement in high-resolution satellite and aerial imagery, this task also increased the spatial accuracy, providing more and more accurate maps of landslide locations. In accordance with the latest developments in the fields of unmanned aerial vehicles and artificial intelligence, the current study is focused on providing an insight into the process of mapping landslides from full-motion videos and by means of artificial intelligence. To achieve this goal, several drone flights were performed over areas located in the Romanian Subcarpathians, using Quadro-Copters (DJI Phantom 4 and DJI Mavic 2 Enterprise) equipped with a 12 MP RGB camera. The flights were planned and executed to reach an optimal number of pictures and videos, taken from various angles and heights over the study areas. Using Structure from Motion techniques, each dataset was processed and orthorectified. Similarly, each video was processed and transformed into a full-motion video, having coordinates allocated to each frame. Samples of specific landslide features were collected by hand, using the pictures and the video frames, and used to create a complete database necessary to train a Mask RCNN model. The samples were divided into two different datasets, having 80% of them used for the training process and the rest of 20% for the validation process. The model was trained over 50 epochs and it reached an accuracy of approximately 86% on the training dataset and about 82% on the validation dataset. The study is part of an ongoing project, SlideMap 416PED, financed by UEFISCDI, Romania. More details about the project can be found at https://slidemap.geo-spatial.ro.
Future Climate Change Impact on Wildfire Danger over the Mediterranean: the case of Greece
Authors: Rovithakis Anastasios , Voulgarakis Apostolos , Grillakis Manolis , Giannakopoulos Christos , Karali Anna
Published: March 2021

The Canadian Fire Weather Index (FWI) is a meteorologically based index designed initially to be used in Canada but it can also be used worldwide, including the Mediterranean, to estimate fire danger in a generalized fuel type based solely on weather observations. The four weather variables are measured and used as inputs to the FWI (rain accumulated over 24 h, temperature, relative humidity, and wind speed) are generally taken daily at noon local standard time.

Recent studies have shown that temperature and precipitation in the Mediterranean, and more specifically in Greece are expected to change, indicating longer and more intense summer droughts that even extend out of season. In connection to this, the frequency of forest fire occurrence and intensity is on the rise. In the present study, the FWI index is used in order to assess changes in future fire danger conditions.

To represent meteorological conditions, regional EURO-CORDEX climate model simulations over the Mediterranean and mainly Greece at a spatial resolution of 11 km, were utilized. In order to assess the impact of future climate change, we used two Representative Concentration Pathway (RCP) scenarios consisting of an optimistic emission scenario where emissions peak and decline beyond 2020 (RCP2.6) and a pessimistic scenario where emissions continue to rise throughout the century (RCP8.5).  We compare the FWI projections for two future time periods, 2021-2050 and 2071-2100 with reference to the historical time period 1971-2000. Based on the critical fire risk threshold values that have been established in previous studies for the area of Greece, the days with critical fire risk were calculated for different Greek domains.
Intelligent recognition of underground pipeline From GPR image based on Hash algorithm
Authors: Li Bo , Zhao Yonghui
Published: March 2021

Ground penetrating radar (GPR) is a high-resolution geophysical non-destructive detection method, which is widely used in near surface target detection, and has been successfully applied in urban construction and geotechnical engineering. In urban life, underground pipelines undertake important missions such as energy transmission and information transmission. As the basic data of smart city, the acquisition of spatial location information of underground pipelines depends on geophysical detection data such as GPR. The traditional recognition and interpretation of  GPR underground pipeline image mainly depends on and is seriously limited by the professional experience of the staff, which is very disadvantageous to the development of large-scale urban underground pipeline survey. To address this problem, according to the GPR reflection image characteristics of isolated targets such as underground pipelines, this paper proposes an intelligent recognition concept of isolated targets in GPR profile based on CBIR (Content-based image retrieval) According to Hash algorithm and improved vector K-means clustering analysis, the intelligent detection, automatic image sorting and recognition of underground pipeline target in GPR profile are realized. Finally, the pipeline material is judged by extracting the image brightness function of the middle trace in the recognition area. The application results of numerical simulation experiments and measured data show that this algorithm can effectively identify the hyperbolic characteristics of the pipeline in the GPR profile, and the identified area can accurately reflect the spatial location of the underground pipeline.
New estimate of growing stock volume and carbon sequestration of Russian forests based on national forest inventory and remote sensing data
Authors: Schepaschenko Dmitry , Moltchanova Elena , Fedorov Stanislav , Karminov Victor , Ontikov Petr , Santoro Maurizio , See Linda , Kositsyn Vladimir , Shvidenko Anatoly , Romanovskaya Anna , Korotkov Vladimir , Bartalev Sergey , Fritz Steffen , Shchepashchenko Maria , Kraxner Florian
Published: March 2021

Since the collapse of the Soviet Union and transition to a new forest inventory system, Russia has reported (FAO, 2014) almost no changes in growing stock (+1.8%) and biomass (+0.6%). Yet remote sensing products indicate increased vegetation productivity (Guay et al., 2014), tree cover (Song et al., 2018) and above-ground biomass (Liu et al., 2015). Here, we challenge the official national statistics with a combination of recent National Forest Inventory and remote sensing data products to provide an alternative estimate of the growing stock of Russian forests and assess the relative changes in the post-Soviet era. Our estimate for the year 2014 is 118.29±1.3 109 m3, which is 48% higher than the official value reported for the same year in the State Forest Register. The difference is explained by increased biomass density in forested areas (+39%) and larger forest area estimates (+9%). Using the last Soviet Union report (1988) as a reference, Russian forests have accumulated 1163×106 m3 yr-1 of growing stock between 1988–2014, which compensates for forest growing stock losses in tropical countries (FAO FRA, 2015). Our estimate of the growing stock of managed forests is 94.2 109 m3, which corresponds to sequestration of 354 Tg C yr-1 in live biomass over 1988–2014, or 47% higher than reported in the National Greenhouse Gases Inventory (National Inventory Report, 2020).

Acknowledgement: The research plots data collection was performed within the framework of the state assignment of the Center for Forest Ecology and Productivity of the Russian Academy of Sciences (no. АААА-А18-118052590019-7), and the ground data pre-processing were financially supported by the Russian Science Foundation (project no. 19-77-30015).
Influence of mesophilic and thermophilic on enrichment and chemical speciation of toxic and valuable elements in digestate
Authors: Zaffar Nazia , Ferchau Erik , Heilmeier Hermann , Wiche Oliver
Published: March 2021

Bioharvesting of toxic and valuable elements by growing high biomass crops in the regions with low-grade mining ores and metal-polluted soils is a new concept in the area of mining termed phytomining. The biomass is used in anaerobic digestion to produce biogas and digestate. To the best of our knowledge, there are limited studies on the enrichment and distribution of heavy metals and economically valuable elements in digestate, obtained from mesophilic and thermophilic fermentation conditions. This study conducted a laboratory experiment to recover and enrich toxic elements (Zn, Cd, Pb, As) and economically valuable elements (Ge and rare earth elements REEs) at mesophilic (37⁰C) and thermophilic (55⁰C) conditions. To analyze the distribution of these elements in the liquid and solid-state of digestate a three-step sequential extraction procedure was carried out. Microfiltration (0.2µm) was used to separate elements in the solid and liquid phases. The solid digestate was extracted with ammonium acetate (pH 7) and ammonium acetate (pH 5) to determine exchangeable and acid-soluble elements. As a result, we found that thermophilic conditions significantly enriched Zn (3%), Cd (48%), Pb (25%), As (21%), Ge (40%), and REEs (22%) compared to mesophilic conditions. The following elements were enriched in decreasing order Cd > Ge > Pb > REEs > As > Zn. This enrichment may be due to differences in availability of substrates to microorganisms and higher gas production with increased temperature. The sequential extraction revealed that the concentration of elements in dissolved form was significantly increased in thermophilic conditions. While the concentrations in exchangeable are decreased indicating that previous elements bound on exchangeable sites were removed and transferred in solution. Furthermore, the element concentration in the residue fraction was not affected by temperature. Possibly the release of secondary metabolites from microorganisms triggered by higher temperature improved the solubility of elements which is an important prerequisite for element separation and recovery.

 
Validation of Aeolus Rayleigh and Mie winds using atmospheric radars in Arctic Sweden and in Antarctica
Authors: Belova Evgenia , Kirkwood Sheila , Voelger Peter , Chatterjee Sourav , Satheesan Karathazhiyath , Hagelin Susanna , Lindskog Magnus , Körnich Heiner
Published: March 2021

So far, validation of Aeolus winds for the polar regions has been based on the ECMWF global data assimilation and forecasting system (e.g. Rennie and Isaksen 2020).  Very few conventional upper air meteorological measurements (radiosondes, aircraft in-situ sensors) are available in the polar regions so the model’s accuracy is not well known in those regions.  There is a risk that different cloud conditions, surface reflectivities and summer daylight in these regions could lead to different performance of the space-borne lidar measurements. At the same time, accurate measurements over the polar regions would be a particular asset to global weather forecasting and climate monitoring as these regions are so poorly covered by other observations. We validate Aeolus Rayleigh and Mie winds by comparison with winds measured by two atmospheric radars, ESRAD and MARA, located at Esrange (68°N 21°E) in Arctic Sweden and at the Indian Antarctic station Maitri (71°S 12°E), respectively, for the period July - December 2019 when reprocessed data for baseline 10 with the telescope mirror temperature correction were available. Data were divided into two seasons: summer with 12 -24 hours direct sunlight and winter covering the rest of the time. Aeolus - radar collocation events are defined when the distance between Aeolus measurement swath and the radar sites is less than 100 km. We computed regression, bias, and standard deviation for the Aeolus winds in comparison with the radars. For Rayleigh winds the slope of regression line is not significantly different from 1, and bias is not significantly different from 0.  Random difference (std) is 4.4 m/s – 7 m/s. For Rayleigh winds at both locations and Mie winds at Esrange we did not find any statistically significant difference between ascending/descending orbits and seasons. However, at Maitri, Antarctica a few m/s bias is found for Mie winds in summer for ascending (evening) passes.