bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of fault and fracture networks to de-risk geological leakage from subsurface energy sites
Authors: Rizzo Roberto Emanuele , Fazeli Hossein , Doster Florian , Kampman Niko , Bisdom Kevin , Snippe Jeroen , Senger Kim , Betlem Peter , Busch Andreas
Published: March 2021

The success of geological carbon capture and storage projects depends on the integrity of the top seal, confining injected CO2 in the subsurface for long periods of time. Here, faults and related fracture networks can compromise sealing by providing an interconnected pathway for injected fluids to reach overlying aquifers or even the surface or sea bottom. In this work, we apply an integrated workflow [1] that, combining single fracture stress-permeability laboratory measurements and detailed fault and fracture network outcrop data, builds permeability models of naturally faulted caprock formations for in situ stress conditions.

We focus our study on two-dimensional (2D) fault-related fracturing within caprock sequences cut by extensional faults. 2D data of fault and fracture networks were collected from an Upper Jurassic to Lower Cretaceous shale-dominated succession in the Konusdalen area (Nordenskioldland, Svalbard, Norway). The studied rock succession represents the regional caprock and seal for the reservoir of the nearby Longyearbyen CO2 Lab. By digitising all the visible features over the images and then inputting them into the open-source toolbox FracPaQ [2], we obtain information about the fault and fracture networks. In particular, we study the variations in fracture size (i.e., length, height) and density distribution near and away from the fault zone(s), together with the connectivity of fractures within the network. These three parameters are fundamental to establish if the network provides permeable pathways. They also enable us to statistically reproduce and upscale a fracture network in a realistic way.

Combining laboratory single fracture stress-permeability measurements with outcrop fracture network data allow us to create an accurate coupled mechanical-hydromechanical model of the natural fracture network and to evaluate the effective permeability of a fault related fracture network. These results are also compared against analytical estimates of effective permeability [3]. With this workflow, we overcome the geometrical simplifications of synthetic fracture models, thus allowing us to establish representative stress-permeability relationships for fractured seals of geological CO2 storage.

Reference: [1] March et al., 2020, Preprint; [2] Healy et al., 2017, JSG; [3] Seavik & Nixon, 2017, WRR
Magnitude Estimation and Onsite Earthquake Early Warning using Cumulative Absolute Velocity in Taiwan
Authors: Huang Hao-Yun , Wu Yih-Min
Published: March 2021

Real-time magnitude determination is one of the critical issues for earthquake early warning (EEW). Magnitude determination may have saturation situation using initial seismic signals after an earthquake occurrence. Previous studies utilized eventual cumulative absolute velocity (eCAV) to determine magnitude up to 9.0 without any saturation. However, to determine eCAV will be too late for EEW application. In order to shorten time to obtain eCAV, 4,754 strong motion records from 64 events with ML large than 5.5 in Taiwan are used to establish the relationship between eCAV and initial shaking parameters (initial CAV, initial cumulative absolute displacement, initial cumulative absolute integral displacement,  Pd and  τc) from 1 s to 20 s after P arrival. Our preliminary results show that eCAV can be estimated using initial shaking parameters. Logarithm linear correlation coefficients vary from 0.78 to 0.97 with standard deviations from 0.27 to 0.10 for time windows from 1 s to 20 s after P arrival. Eventually, we can timely estimate eCAV for magnitude determination as well as or on-site EEW purpose.
Superdivergence of the Atlantic Ocean and Superconvergence around the South China Sea: A Comparison
Authors: Li Sanzhong , Suo Yanhui , Foulger Gillian , Jiang Zhaoxia , Liu Yongjiang
Published: March 2021

Under the influence of the three global tectonic systems of the Paleo-Asian, Pacific and Tethyan dynamic systems, East Asia underwent diverse assemblies of many minor plates, blocks, micro-blocks or micro-plates after the Triassic. We refer to these assemblies as super-convergence related to the Supercontinent Amersia over the subsequent 300 Ma. Three cratons in China – the North China, South China and Tarim blocks – form the center of this super-convergent region. The peak of the super-convergence event is the Yanshannian Movement, which occurred in the Jurassic. This was related to the breakup of the Supercontinent Pangea and the assembly of the future Supercontinent Amersia (Pangea Ultima).

Opening of the South China Sea Basin in the Cenozoic is thought to have been driven by two tectonic systems, the western Pacific Subduction Zone and the Neo-Tethyan Collision-Subduction System. Its tectonic setting is different from that of the North Atlantic. Since 16 Ma, the Cenozoic South China Sea has been closing in the tectonic setting of the circum-East Asian subduction system. Closing of the South China Sea Basin indicates the initial assembly of the Supercontinent Amersia. Tomographic images show the Pacific slab in the mantle transition zone is broken into many mantle micro-blocks and developed later than 30 Ma although its ages are 90 - 130 Ma. This indicates the super-convergence must be driven by powerful forces that fragment the single large-scale oceanic plate.

 

The Atlantic Ocean has been opening since 150 Ma, from south to north. It is related to the breakup of the Supercontinent Pangea. Its opening mechanism has been much discussed. The two main models are a) a chain of deep-mantle plumes along which the mid-Atlantic ridge formed, and b) “back-arc” extension behind the Alpine subduction zones.

It is unlikely that Pangea was a young supercontinent that emerged from an earlier Proto-Pangea (Sanzhong Li et al., 2018). Instead, it is likely an intermediate stage of the long process of supercontinent evolution from Proto-Pangea to a future Amersia.
Study on the Variation Trend of Potential Evapotranspiration in the Three-River Headwaters Region in China Over the Past 20 years
Authors: Wen Xiaohang , Pan Wenqi , Sun Xiaoguang , Li Maoshan , Luo Siqiong
Published: March 2021

To study the variation trend of potential evapotranspiration (PET) in the Three-River Headwaters (TRH) region of the Qinghai-Tibet Plateau in China, we use 2-m temperature and surface pressure observation data from 14 meteorological weather stations in the TRH region, and the surface PET is calculated by the Penman-Monteith formula. The global land surface data assimilation system from 2000 to 2018 were used to compare and verify the accuracy and applicability of the calculated PET in the THR region. The results show that in the past 20 years, the PET of 14 weather stations in the TRH region has shown an increasing trend, with annual averaged growth rate of 1.4 ± 1.2 mm·a−1 , and the spatial distribution of the annual variation rate of PET has obvious difference. PET is higher in the eastern area of TRH region, and lower in the western area. The drought in this area increased from southeast to northwest, which was consistent with the spatial distribution of precipitation. The aridity index K has flfluctuated and increased before 2015, but there was a sudden change in 2018, and the aridity index K in the TRH began to decline after 2018, and the climate changed from dry to wet.
Characteristics and mechanism of annual sea level variability in the southern tropical  Indian Ocean
Authors: Huang Ke
Published: March 2021

The first baroclinic mode Rossby wave is known to be of critical importance to the annual sea level variability in the southern tropical Indian Ocean (STIO; 0°–20°S, 50°–115°E). In this study, an analysis of continuously stratified linear ocean model reveals that the second baroclinic mode also has significant contribution to the annual sea level variability (as high as 81% of the first baroclinic mode). The contributions of residual high-order modes (3 # n # 25) are much less. The superposition of low-order (first and second) baroclinic Rossby waves (BRWs) primarily contribute to the high energy center of sea level variability at ;108S in the STIO and the vertical energy penetration below the seasonal thermocline. We have found that 1) the low-order BRWs, having longer zonal wavelengths and weaker damping, can couple more efficiently to the local large-scale wind forcing than the high-order modes and 2) the zonal coherency of the Ekman pumping results in the latitudinal energy maximum of low-order BRWs. Overall, this study extends the traditional analysis to suggest the characteristics of the second baroclinic mode need to be taken into account in interpreting the annual variability in the STIO.
Morphodynamic forecast uncertainty due to bathymetry unknowns
Authors: Sánchez-Artús Xavier , Gracia Vicente , Espino Infantes Manuel , Sánchez-Arcilla Conejo Agustín
Published: March 2021

Operational morphodynamic modelling is becoming an attractive tool for managers to forecast and reduce coastal risks. The development of highly sophisticated numerical models during the last decades has underpinned the simulation of beach morphological evolution due to wave impacts. However, there are still some fundamental aspects, such as the bathymetric uncertainty, that needs to be regularly updated in the modelling chain to avoid a worthless forecast. It is also very well known that the surf zone is the most highly dynamic area although the bathymetry changes between certain limits. In this work, we explore the influence of bathymetric changes in morphodynamic forecasts. XBEACH is used to model the morphological response of a dissipative urban low-lying sandy coastal stretch (Barcelona, Spain) for different forecasted storms to determine the uncertainty bands of predicted coastal erosion and flooding. We consider as benchmarks the results of XBEACH simulations fed with the bathymetric information taken from existing nautical charts. An analysis of the possible beach states of the studied area following the Wright and Short (1984) is later performed to determine a range of topo-bathymetric configurations that will be used to run the model again. These new simulations are used to determine the uncertainty of the erosion and flooding results. The energy content of the storm in terms of intensity and duration uncertainty is also considered in the analysis. The proposed ensemble approach will serve to determine the likelihood of the modelling forecast outputs. Such statistical characterization is aligned with ensemble forecasting in meteo-oceanographic fields and will provide robust information for coastal decision making, for instance when considering proactive rapid deployment measures against a forecasted storm.
Estimate of hydrodynamic parameters with a coupled hydrogeophysical inversion using GPR surveys
Authors: Moua Rohianuu , Lesparre Nolwenn , Girard Jean-François , Belfort Benjamin , Lehmann François
Published: March 2021

We develop a methodology to estimate soil hydrodynamic parameters from a water infiltration experiment monitored with a GPR (Ground Penetrating Radar). Such an experiment, carried out on both controlled and natural site, consists in applying a water charge in a tank on the soil surface. During the water infiltration, the water layer thickness above the soil surface in the tank and the GPR response on the infiltration water front are monitored. The infiltration experiment is then modelled numerically using hydrogeological parameters which describe the constitutive relationships between water content, pressure and hydraulic conductivity. In that goal, we use the WAMOS-1D code which combines the 1D Richards equation and the Mualem – van Genuchten model. From the hydrogeological models outputs and petrophysical relationships, corresponding GPR velocity models are created to generate the resulting GPR signals. Then, an inversion algorithm couples both the hydrogeological and the geophysical models to seek the optimal hydrodynamic parameters. The inverse problem objective function is calculated from the estimated arrival time of the GPR waves reflected by the water infiltration front and compared to the measured ones. Preliminary inversion tests explore the hydrodynamic parameters space using synthetic data. First results show that the saturated hydraulic conductivity parameter can be estimated. Further tests are performed to improve both our experimental set-up and methodology and allow an estimation of the other hydrodynamic parameters. An emerging idea is to complete the objective function by analyzing the arrival time corresponding to additional reflectors to the water infiltration front.
Applicability and performance of seismic sources in clay
Authors: Wawerzinek Britta , Lüth Stefan , Esefelder Roman , Giese Rüdiger , Krawczyk Charlotte M.
Published: March 2021

Since clay formations are heterogeneous and anisotropic, their seismic characterization at the meso scale is challenging. To tackle this problem, experiments using different seismic sources were undertaken in the Mont Terri Underground Rock Laboratory (URL). The first experiment was carried out using impact and vibroseis sources which were particularly designed for seismic exploration in the underground. The second experiment was conducted using an ELVIS vibration source (Polom et al. 2011) which was mainly designed for near-surface investigations on roads or in open terrain.

The first experiment focused on the applicability and performance of the modular underground system (Borm & Giese 2003) in clay. It demonstrates the successful application of impact and vibroseis source in Opalinus clay. The impact source generates signals with high signal-to-noise ratios and strong lower frequencies (above 100 Hz). Due to that, the impact source is preferred for applications at large offsets. In contrast the vibroseis source has more control of the frequency generation and is able to excite higher frequencies (up to 12 kHz) than the impact source. Therefore, the vibroseis source is preferred for high-resolution applications at near offsets.
Both sources are also suitable for clay characterization and reflection imaging. Travel time analyses resulted in average P- and S-wave velocities that show a clear azimuthal dependence. The carbonate-rich sandy and the sandy facies are characterized by faster velocities than the shaly facies which is stronger anisotropic than the sandy facies. Our findings are in good agreement with seismic velocities and anisotropy determined by Schuster et al. (2017), Popp & Salzer (2007) and Siegesmund et al. (2014). Although the sparse acquisition geometry was not optimal for reflection imaging of the geological conditions around the URL, later arriving shear wave reflections could be extracted from the impact data. A 3D migration focuses these reflections at a distance of ~50 m at the transition from the lower sandy facies to the upper shaly facies.

The second experiment of our pilot survey focused on seismic reflection measurements using near-surface equipment to evaluate its applicability in URLs. Since the ELVIS source was combined with the 3-C geophones of the main experiment, the acquisition geometry was not optimal to image settings beneath the URL. The acquired ELVIS data were dominated by strong surface waves. After their removal, surface wave reflections appeared which mainly map the structural elements of the URL. The test measurements confirmed a general applicability of ELVIS in the tunnel, however it also indicates the need to improve the acquisition geometry.
Combined use of Sentinel-2 images and Sentinel-1-derived moisture maps for soil organic carbon content mapping in croplands, South-western France
Authors: Urbina Salazar Diego , Vaudour Emmanuelle , Baghdadi Nicolas , Ceschia Eric , Arrouays Dominique
Published: March 2021

In terms of agronomy, soil organic carbon (SOC) content is important for crop growth and development. From the environmental viewpoint, SOC sequestration is essential to mitigate the emission of greenhouse gases into the atmosphere. The use of sensors for carbon monitoring over croplands is a key issue in recent works. Sentinel-1/2 (S1, S2) satellites acquire data with regular frequency (weekly) and high spatial resolution (10 and 20 meters). Previous studies have demonstrated their potential for quantification of soil attributes including topsoil organic carbon content on single dates. Soil surface roughness and soil moisture influence the performance of spectral models according to acquisition date, particularly surface soil moisture (SM), as shown by multidate models of predicted SOC content (Vaudour et al., 2021). Still, the sensitivity of Sentinel-1/2 to SM must be better understood and exploited for a given single date. A possible solution to determine the influence of SM on single date model performance consists of including it as a covariate.

In order to predict the topsoil SOC content over croplands in the Pyrenees region, France (22177 km²), this study addresses: (i) the influence of the Sentinel image date and that of the soil sampling year; (ii) the contribution of SM products derived from the Sentinel-1/2 data (El Hajj et al., 2017) in the spectral models.

The influence of the image date and soil sampling date was analyzed for springs 2017 and 2018. Clouds, shadows and NDVI (> 0.35) values were excluded from the images. Best single performances (RPD ≥ 1.3) were scored for soil sampling sets collected in 2016-2018. The same dates were analyzed using either SM maps, or signal values of VV and VH polarizations from S1 images. SM or polarization values were extracted for each sample and integrated into the partial least squares regression (PLSR) models, respectively. The best performance (RPD = 1.57) was obtained with SM as a covariate in 2017, with lowest mean SM throughout the map.

 

References

El Hajj, M.; Baghdadi, N.; Zribi, M.; Bazzi, H. Synergic Use of Sentinel-1 and Sentinel-2 Images for Operational Soil Moisture Mapping at High Spatial Resolution over Agricultural Areas. Remote Sensing 2017, 9, 1292, doi:10.3390/rs9121292.

Vaudour, E.; Gomez, C.; Lagacherie, P.; Loiseau, T.; Baghdadi, N.; Urbina-Salazar, D.; Loubet, B.; Arrouays, D. Temporal Mosaicking Approaches of Sentinel-2 Images for Extending Topsoil Organic Carbon Content Mapping in Croplands. International Journal of Applied Earth Observation and Geoinformation 2021, 96, 102277, doi:10.1016/j.jag.2020.102277.
Spatial distributions of cloud droplet size distributions from cloudbow observations measured with specMACS
Authors: Pörtge Veronika , Kölling Tobias , Zinner Tobias , Forster Linda , Emde Claudia , Mayer Bernhard
Published: March 2021

The evolution of clouds and their impact on weather and climate is closely related to the cloud droplet size distribution, which is often represented by two parameters: the cloud droplet effective radius (reff) and the effective variance (veff). The droplet radius (reff) determines the radiative effect of clouds on climate. The effective variance is a measure of the width of the size distribution which is, for instance, important to understand the formation of precipitation or entrainment and mixing processes. We present an airborne remote-sensing technique to determine reff and veff from high-resolution polarimetric imaging observations of the LMU cloud camera system specMACS.

Recently the spectral camera system has been upgraded by a wide-field polarization resolving RGB camera which was operated for the first time on the HALO aircraft during the EUREC4A campaign. The new polarimeter is ideally suited for observing the cloudbow - an optical phenomenon which forms by scattering of sunlight by liquid water cloud droplets at cloud top. The cloudbow is dominated by single scattering which has two implications: Its visibility is significantly enhanced in polarized measurements and its structure is sensitive to the cloud droplet size distribution at cloud top. This allows the retrieval of reff and veff by fitting the observed polarized cloudbow reflectances against a look-up table of pre-computed scattering phase functions.

The characteristics of the polarimeter are optimized for the measurement of the cloudbow. The wide field-of-view is key for observing the cloudbow (scattering angle 135° -165°) for a wide range of solar positions. Another advantage is the high spatial and temporal resolution which allows the study of small-scale variability of cloud microphysics at cloud top with a horizontal resolution of up to 20 m. Combining the polarimetric cloudbow technique with an existing stereographic retrieval of cloud geometry allows to derive vertical profiles of the droplet size distribution at cloud top. Observations of different EUREC4A cloud fields are used to demonstrate the retrieval technique and to present first spatial distributions and vertical profiles of cloud droplet size distributions.
Multiscale fracture density analysis at Stromboli Volcano, Italy: implications to flank stability
Authors: Alcock Thomas , Vinciguerra Sergio , Benson Phillip , Vagnon Federico
Published: March 2021

Stromboli volcano has experienced four sector collapses over the past 13 thousand years, resulting in the formation of the Sciara del Fuoco (SDF) horseshoe-shaped depression and an inferred NE / SW striking rift zone across the SDF and the western sector of the island. These events have resulted in the formation of steep depressions on the slopes on the volcano where episodes of instability are continuously being observed and recorded. This study aims to quantify the fracture density inside and outside the rift zone to identify potential damaged zones that could reduce the edifice strength and promote fracturing. In order to do so we have carried out a multiscale analysis, by integrating satellite observations, field work and seismic and electrical resistivity analyses on cm scales blocks belonging to 11 lava units from the main volcanic cycles that have built the volcano edifice, ie. Paleostromboli, Nestromboli and Vancori. 0.5 m resolution Pleiades satellite data has been first used to highlight 23635 distinct linear features across the island. Fracture density has been calculated using Fracpaq based on the Mauldon et al (2001) method to determine the average fracture density of a given area on the basis of the average length of drawn segments within a predetermined circular area. 41.8 % of total fracture density is found around intrusions and fissures, with the summit area and the slopes of SDF having the highest average fracture density of 5.279  . Density, porosity, P- wave velocity in dry and wet conditions and electrical resistivity (in wet conditions) were measured  via an ultrasonic pulse generator and acquisition system (Pundit) and an on purpose built measuring quadrupole on cm scale blocks of lavas collected from both within and outside the proposed rift zone to assess the physical state and the crack damage of the different lava units.  Preliminary results show that P-wave velocity between ~ 2.25 km/s < Vp < 5km/s decreases with porosity while there is high variability electrical resistivity with 21.7 < ρ < 590 Ohm * m. This is presumably due to the lavas texture and the variable content of bubble/vesicles porosity and crack damage, that is reflected by an effective overall porosity between 0 and 9 %. Higher porosity is generally mirrored by lower p-wave velocity values. Neostromboli blocks show the most variability in both P-wave velocity and electrical resistivity. Further work will assess crack density throughout optical analyses and systematically investigate the UCS and elastic moduli. This integrated approach is expected to provide a multiscale fracture density and allow to develop further laboratory testing on how slip surfaces can evolve to a flank collapse at Stromboli.
Analysis of Surface Air Pollutant Measurements from 2015-2019 in India
Authors: Sharma Disha , Mauzerall Denise
Published: March 2021

Launched among growing concerns about air pollution in India, the National Clean Air Program (NCAP) 2019 aims to reduce PM2.5 concentrations by 20-30% by 2024, relative to 2017. This analysis is an overview of air pollution levels in India in the five years prior to implementation of the NCAP program and provides a baseline to evaluate its future success. We analyze ground observations from 2015 – 2019, of five criteria pollutants – PM10, PM2.5, SO2, NO2 and O3. We use data retrieved from the continuous and manual monitors across India to calculate annual average concentrations, seasonal cycles and monthly variability of these five pollutants in northern and southern India (divided at 23.5 oN). We find that northern India has (7%-129%) higher average concentrations of all pollutants compared with southern India, except for SO2 where the concentrations are similar.  Particulate pollution dominates the pollution mix with virtually all sites in the northern region failing to meet the annual average PM10 and PM2.5 national ambient air quality standards (NAAQS) (of 60 g/m3 and 40 g/m3, respectively) while some sites in southern India meet the standard. Although inter-annual variability exists, no significant trend of these pollutant concentrations was observed over the five-year period.  We also conduct case studies in five cities included in the US State Department Air-Now PM2.5 network - Delhi, Kolkata, Mumbai, Hyderabad and Chennai and include continuous monitoring data. We find the annual average PM10 and PM2.5 NAAQS concentrations to be frequently exceeded in these cities with highest concentrations found in Delhi, followed by Kolkata. SO2 concentrations, however, generally meet the NAAQS standard in all the five cities.  NO2 NAAQS are exceeded in Delhi, Kolkata and Hyderabad in winter whereas O3 only occasionally exceeds NAAQS in Delhi.   Our work creates a framework that can be used in future research to evaluate the success of the NCAP air pollution mitigation program.
Get HyP3! SAR processing for everyone
Authors: Kennedy Joseph H. , Hogenson Krik , Johnston Andrew , Kristenson Heidi , Lewandowski Alex , Logan Thomas A. , Meyer Franz J. , Rine James
Published: March 2021

Synthetic Aperture Radar (SAR), with its capability of imaging day or night, ability to penetrate dense cloud cover, and suitability for interferometry, is a robust dataset for event/change monitoring. SAR data can be used to inform decision makers dealing with natural and anthropogenic hazards such as floods, earthquakes, deforestation and glacier movement. However, SAR data has only recently become freely available with global coverage, and requires complex processing with specialized software to generate analysis-ready datasets. Furthermore, processing SAR is often resource-intensive, in terms of computing power and memory, and the sheer volume of data available for processing can be overwhelming. For example, ESA's Sentinel-1 has produced ~10PB of data since launch in 2014. Even subsetting the data to a small scientific area of interest can result in many thousands of scenes, which must be processed into an analysis-ready format.

The Alaska Satellite Facility (ASF) Hybrid Pluggable Processing Pipeline (HyP3), which is now out of beta and available to the public, provides custom, on-demand processing of Sentinel-1 SAR data at no cost to users. HyP3 is integrated directly into Vertex, ASF's primary data discovery tool, so users can easily select an area of interest on the Earth, find available SAR products, and click a button to send them (individually, or as a batch) to HyP3 for Radiometric Terrain Correction (RTC), Interferometric SAR (InSAR), or Change Detection processing. Processing leverages AWS cloud computing and is done in parallel for rapid product generation. Each process provides options to customize the processing and final output products, and provides metadata-rich, analysis-ready final products to users.

In addition to the Vertex user interface, HyP3 provides a RESTful API and a python software developers kit (SDK) to allow programmatic access and the ability to build HyP3 into user workflows. HyP3 is open source and designed to allow users to develop new processing plugins or stand up their own custom processing pipeline.

We will present an overview of using HyP3, both inside Vertex and programmatically, and the available output products. We will demonstrate using HyP3 to investigate the consequences of natural hazards and very briefly discuss the technologies and software design principles used in the development of HyP3 and how users could contribute new plugins, or stand up their own custom processing pipeline.
Could the Beirut Explosion perturb the Ionosphere? Pre-results Using TEC-GNSS observations.
Authors: Freeshah Mohamed , Zhang Xiaohong , Şentürk Erman , Ren Xiaodong , Adil Muhammad Arqim , Xu Guozhen
Published: March 2021

Natural hazards such as shallow earthquakes and volcanic explosions are known to generate acoustic and gravity waves at infrasonic velocity to propagate in the atmosphere layers. These waves could induce the layers of the ionosphere by change the electron density based on the neutral particles and free electrons coupling. Recently, some studies have dealt with some manmade hazards such as buried explosions and underground nuclear explosions which could cause a trigger to the ionosphere. The Global Navigation Satellite Systems (GNSS) provide a good way to measure ionospheric total electron content (TEC) through the line of sight (LOS) from satellite to receiver. The carrier-to-code leveling (CCL) technique is carried out for each continuous arc where CCL eliminates potential ambiguity influence and it degrades the pseudo-range noise. Meanwhile, the CCL retains high precision in the carrier-phase. In this study, we focus on the Beirut Explosion on August 4, 2020, to check slant TEC (STEC) variations that may be associated with the blast of Beirut Port. The TECs were analyzed through the Morlet wavelet to check the possible ionospheric response to the blast. An acoustic‐gravity wave could be generated by the event which could disturb the ionosphere through coupling between solid earth-atmosphere-ionosphere during the explosion. To verify TEC disturbances are not associated with space weather, disturbance storm-time (Dst), and Kp indices were investigated before, during, and after the explosion. The steady-state of space weather before and during the event indicated that the observed variations of TEC sequences were caused by the ammonium nitrate explosion. There was a large initial explosion, followed by a series of smaller blasts, about ~30 seconds, a colossal explosion has happened, a supersonic blast wave radiating through Beirut City. As a result of the chemistry behind ammonium nitrate’s explosive, a mushroom cloud was sent into the air. We suggest that these different explosions in strength and time could be the reason for different time arrival of the detected ionospheric disturbances over GNSS ground-based stations.
Application of the microbiomorphic (phytolith) analysis in the geoarchaeological study of the land-use at the Voorthuizen-Wikselaarseweg archaeological site (Netherlands) 
Authors: Druzhinina Olga , van den Berghe Kasper , Golyeva Alexandra
Published: March 2021

In 2018, the Voorthuizen-Wikselaarseweg archaeological site was excavated. This settlement dates back to Roman and Medieval times and is located in the central part of the Netherlands: the so-called Gelderse Vallei, an area build-up of fluvioperiglacial and eolian sands. Questions related to the anthropogenic influence of settlers on the surrounding landscape, as well as the specification of the ancient agricultural activity, were among the main research tasks posed to this archaeological study. Despite the fact that modern geoarchaeology offers a variety of methods of researching archaeological sites, in practice, the vast majority of archaeological work in the Netherlands is limited to the use of palynological and macrobotanical analyzes and radiocarbon dating. The choice of research methods in relation to the sandy cultural layer is especially narrow as it is assumed to bear worse conditions of preservation of traces of anthropogenic activity.

For the investigation of the sandy cultural layer of Voorthuizen, a method of microbiomorphic (phytolith) analysis was proposed. The information that is given by this method is different from that provided by palynological study (though they strongly complement each other). While pollen provides a general insight into the plant growth in the region around the settlement, phytoliths (silica copies of plant cells)  present data on the plant species grown, eaten, and used on the settlement itself. This information is contained in the old living layer, as well as in the pits (working places and waste pits), postholes, ditches etc. The combination of phytoliths and other microbiomorphs (e.g. detritus, diatoms, etc.) essentially broadens the range of palaeoecological information.

In Voorthuizen 34 samples have been collected and processed according to standard sample treatment technique (Golyeva, 2008). All samples were found to be suitable for analysis, with a sufficient number of microbiomorphs.

The results of the study not only allow to clarify significantly the archaeological interpretation of the site but also provides new information on the anthropogenic impact on the landscape. Microbiomorphic analysis manifests the genesis of the cultural layer and the several phases and types of anthropogenic use of the territory. The research also demonstrates the applicability of the microbiomorhic (phytolith) analysis in the case of sandy archaeological layers.

References:

Golyeva А. А., Microbiomorphic complexes of natural and anthropogenic landscapes. Genesis, geography, informative capacity (LKI, Moscow, 2008) (in Russian).
Wet Deposition Fluxes of Nitrate and Ammonium at a Rural Agricultural Site in north India
Authors: Yadav Sudesh , Kulshrestha Umesh
Published: March 2021

The chemical composition of rainwater is an indicator of the air quality and sources of influence. In this study, pH and ionic concentrations were measured in rain samples collected during monsoon season of 2018 at a rural agricultural site located in northern part of India. Wet deposition fluxes of reactive nitrogen species NH4+ over NO3- were calculated to estimate their annual deposition. The pH of samples varied between 5.2 and 6.14, with an average value of 5.72 which is in alkaline range considering 5.6 as the neutral pH of cloud water with atmospheric CO2 equilibrium. These relatively high pH values indicate the neutralisation of acidity in precipitation. Samples were analysed for their cationic and anionic content using ion chromatography. The results showed that NH4+ concentrations were higher than NO3- with the VWM concentrations of 187.23 μeql-1 and 26.79 μeql-1 respectively. Furthermore, wet deposition flux of NH4+-N was calculated as 4.25 kg ha-1 yr-1 while that of NO3--N was as 2.10 kg ha-1 yr-1. VWM concentrations of major ions decreased in the following order NH4+ > Ca2+ > SO42- > NO3- > K+ > Cl- > Na+ > Mg2+. In this study, relatively high NH4+ concentrations in rainwater can be attributed to nearby agricultural activities, excreta and biomass burning.

Keywords: Rainwater, Neutralisation, VWM concentration, Agricultural site, Reactive Nitrogen.
Evidence of tsunami deposits in East Tunisia coastline contemporaneous of the AD 365 Crete earthquake: Field data and modelling 
Authors: Bahrouni Nejib , Meghraoui Mustapha , Bayraktar Hafize Başak , Lorito Stefano , Zagrarni Mohamed Fawzi , Bel Mabrouk Nabil
Published: March 2021

New field investigations along the East Tunisian near Sfax coastline reveal sedimentary deposits that may account for a catastrophic event. The sedimentary unit is made of sand coarse gravels, limestone beach-rock, mixed with broken shells of marine gastropods and lamellibranch mollusks, bones and organic matter. Near Thyna, at El Amra site located north of Sfax city, 3.2 m to 3.6 m high late Quaternary coastal terraces are spread over the coastline; they contain a catastrophic deposit that often cover archeological sites of the Roman period. The stratigraphic units show a succession of sandy-silty paleosol truncated by 40 to 70-cm-thick catastrophic unit which is covered in some sites by fire remains overlain by a relatively thin (~10 cm) sandy-silty aeolian unit. The sedimentary succession ends with about 1-m-thick of alluvial deposits and paleosol units. Charcoal samples collected at 10 cm below and 4 cm above the catastrophic units provide radiocarbon dating 236 - 385 cal AD and 249 – 541 cal AD (2s), respectively. Radiocarbon ages bracket the catastrophic unit that may refer to the major tsunamigenic earthquake of 21 July 365 (Mw ~ 8) in west Crete (Greece) reported to have inundated coastlines of Sabratha in Libya and Alexandria in Egypt. The nonlinear shallow water Tsunami-HySEA code is used to perform numerical modelling using 2 different seismic sources comparable to that of the AD 365 Crete earthquake. They feature 2 principal mechanisms that accommodate the Nubia-Aegean convergence along the Hellenic Arc, namely a shallowly dipping thrust-faulting on the subduction interface, as well as a steeper splay faulting in the overriding material. The maximum tsunami wave heights distribution calculated along the Tunisia coast peak in both cases at about 3 meters. The run-up caused by these sources, also considering that we have used uniform slip on the causative fault, can be significantly higher. This proves that the tsunami waves may have reached Tunisia where several coastal cities where severely damaged and reported to have stopped their economic activity. With the identification of the 365 tsunami deposits in eastern coast of Tunisia, the tsunami hazard and risk associated with a major earthquake from the western Hellenic subduction zone cannot be ruled out.
Intensity and frequency of extreme novel epidemics
Authors: Marani Marco , Katul Gabriel , Pan William , Parolari Anthony
Published: March 2021

Human-natural processes that generate extreme events with large financial, social, and health consequences,  are inherently non-stationary due to ever-changing anthropogenic pressures and societal exposure. The issues posed by non-stationarity are recognized and addressed in Earth system science.  However, extensive epidemiological information remains fragmented and virtually unexplored from this perspective due to the lack of approaches to leverage observations of a heterogeneous past. To address this gap, we assembled a long historical record (1600-present) of infectious disease epidemics from the literature.  This new record enabled the development and applications of methods to quantify the time-varying probability of occurrence of extreme epidemic events. We define the intensity of epidemic events, the number of deaths/time/global population, and find that observations from several hundred years, covering almost four orders of magnitude of epidemic intensity, follow a probability distribution  with a slowly-decaying power-law tail (Generalized Pareto Distribution, asymptotic exponent = -0.705). To the contrary, the yearly number of epidemics is non-stationary, implying that conventional extreme value analyses are inappropriate.  We find that the rate of occurrence of extreme epidemics varies nine-fold over centennial time scales, from about 0.4 to 3.6 epidemics/year. As a result, yearly occurrence probabilities of extreme epidemics are far from constant:  The intensity computed for the most extreme event on record – the “Spanish Influenza” of 1918-1920 – has a probability of occurrence varying from 0.27 to 1.75 %/year in the time frame from 1600 to present. When optimistically assuming that 1 year is required to develop, produce, and begin distributing a vaccine/treatment for a new disease (e.g. the recent COVID-19 case), we estimate that the average recurrence time of a pandemic killing most of the global population is now less than 12,000 years.
Tree ring research in the Himalayas – a key resource for extending environmental records into the pre-instrumental period
Authors: Islam Nazimul , Vennemann Torsten , Lane Stuart N.
Published: March 2021

Original dendrochronological research has developed rapidly over the last few decades to cover a wide range of environmental reconstruction, not only mean climate conditions but also climate extremes (e.g. floods, droughts) and other environmental hazards (e.g. landslides, debris flows, sea-level rise, volcanic eruptions). Similarly, the focus has expanded its geographical coverage from the temperate and high latitudes to lower latitudes (e.g.  the Himalaya, Tibet Plateau). Analysis of the two main dedicated dendrochronology journals (Dendrochronologia (2002-) and Tree Ring Research (2015-)) shows that the focus of the majority of published papers has been temperate and high latitudes and many fewer have considered lower latitudes such as the Himalaya. This may be due to the long-lasting controversy and doubt of the existence of tree-rings in lower latitude trees and the lower scientific acceptance of seasonal tree growth in such regions. However, such regions have some of the most preferred tree species (e.g. Larix griffithii, Abies spectabilis, Betula utilis, Juniperus polycarpos etc) for dendrochronological analysis making them suitable for tree-ring research and for answering questions regarding century-scale and longer environmental changes in regions with a relatively short history of instrumented recording of environmental parameters.

Perhaps the most interesting development in tree ring research is the realization that tree cellulose can be used to acquire information not only of climatic significance but also hydrological significance, by using environmental isotopes. To date, despite of being one of the most climate and geopolitically sensitive regions, the Himalaya has got very less or no attention for combined research of isotopes and anatomical analysis of tree rings. Based on its huge significance, it is critical to combine these two methods to allow us to make linkages between historical climate fluctuations and associated hydrological response. In this poster, we present the conception of a project to do this in a large catchment (4264 km2) in the Sikkim Himalaya with the purpose to understand how climate change is simultaneously impacting both water-related risks and water-related resources and crucially how far downstream which is highly significant as millions of people living downstream get freshwater from the seasonal snow and glacier-melt in this part of the Himalayas.
Regional oceanic and biogeochemical modeling strategy :forced or coupled model ?
Authors: Oerder Véra , Auger Pierre-Amaël , Bento Joaquim , Hormazabal Samuel
Published: March 2021

 Regional high resolution biogeochemical modeling studies generaly use an oceanic model forced by prescribed atmospheric conditions. The computational cost of such approach is far lower than using an high resolution ocean-atmosphere coupled model. However, forced oceanic models cannot represent adequately the atmospheric reponse to the oceanic mesoscale (~10-100km) structures and the impact on the oceanic dynamics.

To assess the bias introduce by the use of a forced model, we compare here a regional high resolution (1/12º) ocean-atmosphere coupled model with oceanic simulations forced by the outputs of the coupled simulation. Several classical forcing strategies are compared : bulk formulae, prescribed stress, prescribed heat fluxes with or without Sea Surface Temperature (SST) restoring term, .... We study the Chile Eastern Boundary Upwelling System, and the oceanic model includes a biogeochemical component,

The coupled model oceanic mesoscale impacts the atmosphere through surface current and SST anomalies. Surface currents mainly affect the wind stress while SST impacts both the wind stress and the heat fluxes. In the forced simulations, mesoscale structures generated by the model internal variability does not correspond to those of the coupled simulation. According to the forcing strategy, the atmospheric conditions are not modified by the forced model mesoscale, or the modifications are not realistic. The regional dynamics (coastal upwelling, mesoscale activity, …) is affected, with impact on the biogeochemical activity.

 

 

This work was supported by the FONDECYT project 3180472 (Chile), with computational support of the NLHPC from the Universidad de Chile, the HPC from the Pontificia Universidad Catolica de Valparaiso and the Irene HPC from the GENCI at the CEA (France).
Synthesis of Engineered Biochar for Aqueous Pharmaceutical Removal
Authors: Chaubey Abhishek Kumar , Patel Manvendra , Mohan Dinesh
Published: March 2021

Pharmaceuticals cured deadly diseases and enhance the life spans of human beings. But, in the past decade, pharmaceuticals have risen as “contaminants of emerging concern” around the world. The persistence and resistance of pharmaceuticals lead to their accumulation in water bodies. The inefficiency of conventional WWTPs to remove pharmaceuticals also contributed to their environmental presence. Thus, the urgent need for sustainable and economically feasible remediation techniques has become evident. The present study describes the sorption of Acetaminophen from aqueous systems with engineered biochar. The biochars were developed from Mg/Al layered double hydroxides impregnated rice husk biomass at 500 and 700 ℃ in an atmosphere controlled muffle furnace.  The developed engineered biochar was characterized by using CHNS analyzer, ICP-OES, SEM, SEM-EDX, TEM, FTIR, and XRD. Engineered biochar was applied for aqueous pharmaceutical removal in batch mode through pH, isotherm, and kinetic studies. The effect of pyrolysis temperature, pH, concentration, dose, contact time, and sorption temperature have been evaluated. Engineered biochar prepared at 700 ℃ shows significantly higher removal of pharmaceutical as compared to Engineered biochar prepared at 500 ℃ as well as pristine biochar.
An entropy-based investigation on the river recovery potential in a regulated river basin 
Authors: Pradhan Chandan , Padhee Suman , Dutta Subashisa , Bharti Rishikesh
Published: March 2021

River recovery is the process that describes the capacity of the river to adjust to the limiting boundary conditions. In the regulated rivers, altered flow-sediment regime controls the trajectory of adjustments along the geomorphic and vegetative attributes. The present study is focused on recovery potential assessment of Mahanadi River, which shows a gradual emergence of in-channel vegetation in the post-dam period. The study area encompasses (i) 10 km reach of Mahanadi River (M1) having bedrock exposed, anabranching channel pattern and (ii) 102 km reach of Ong river (O1) with alluvial, compound channel form. In this study, Google Earth Engine cloud computing platform is used to process the Landsat images (1980-2010) and vegetation, water, and floodplain geomorphic classes are derived by Normalized Difference Vegetation Index (NDVI) and modified Normalized Difference Water Index (mNDWI). Finally, the intensity disorder index (IDI) is computed to represent the ‘system state’ in the post-monsoon periods and the influence of vegetation growth on the channel recovery. The results show that M1 is relatively stable, with cumulative vegetation area increased from 2% in 1980 to 8% in 2010. However, O1 demonstrates an accelerated increase in vegetation area i.e., 10% in 1980 to 30% in 2010. The system state (IDI) varies between 0.2 and 0.6 and follows a decreasing trend along M1 and O1. The findings establish that both regulated reaches may approach channel recovery in the near future, and prevailing boundary conditions indirectly influence the rate and direction of IDI.        