bluuebunny/crossref_metadata_2025 huggingface dataset:
Results from targeted TLE and geomagnetically conjugate sprites observations from the International Space Station during the Rakia mission
Authors: Yair Yoav , Price Colin , Reuveni Yuval , Yaniv Roy , Sao Sabbas Eliah , Rubanenko Lior
Published: March 2022

The Rakia mission is a private space flight to the ISS, that was executed by the Axiom company in March 2022. The ILAN-ES (Imaging of Lightning And Nocturnal Emissions from Space) is heritage of the MEIDEX conducted on board the space shuttle Columbia in its final mission in January 2003 (Yair et al., 2004). We optimized the limited observation time (2 hours, 12x10 minutes) from the ISS such that only selected targets at prescribed times were imaged by the astronaut. We used an upgraded prediction procedure for potential TLE-producing thunderstorms, based on the verification scheme used during the THOR campaign (Chanrion et al., 2016), and by using the lightning location networks (WWLLN, ENTLN) data for selected active regions. In addition, we computed their magnetic conjugate points, so as to enlarge potential daily targets (geomagnetically conjugate sprites were never recorded from space; Marshal et al., 2005).

The camera used during ILAN-ES was a Nikon D6 set at 6400 ISO and recording 24 frames per second at 1920 x 1080 pixels. It was mounted with a 58mm/f1.2 lens, giving a 34.4o x 19.75o field of view corresponding to 1.07’/pixel. With these settings, the camera resolution was 130 m at nadir. The camera The astronauts operated the camera from the Copula window of the ISS while visually tracking lightning activity and directing the camera towards the bright flashes. When conjugate targets were allocated, the aim was to conduct nadir viewing.

To overcome the challenge of manual detection of lightning and transient luminous events in the video footage, we will harness several Machine Learning (ML) and Deep Learning (DL) techniques. A comprehensive ground-based campaign accompanied the ISS observations, most notably by the ground-based LEONA network in South America and by schools in Ghana, Rwanda and Zimbabwe.

This presentation will discuss mission operations and the results of the ISS and ground observations.

 
Migration of Reversing Dunes Against the Sand Flow Path as a Singular Expression of the Speed-Up Effect
Authors: Gao Xin , Narteau Clément , Gadal Cyril
Published: March 2022

We study the morphodynamics of reversing dunes on the gravel deposits of the alluvial fan of the Molcha river at the border between the Tibetan Plateau and the Taklamakan Desert (Gao et al., 2021). Independent sets of wind data show that this area of low sand availability is exposed to two prevailing winds from opposite directions and of different strengths. The predicted resultant transport direction of sand particles is westward. Nevertheless, satellite observations combined with field measurements and ground-penetrating radar surveys reveal that isolated dunes a few meters high migrate eastward. This apparent dune migration paradox is resolved using numerical and analytical models that take into account the speed-up effect and the continuous change in dune shape after each wind reversal. When a newly established wind hits what was before the steeper lee slope of the dune, the sand flux at the crest abruptly increases before relaxing back to a constant value as the crest migrates downwind and as the dune reaches a new steady shape. Integrated over the entire wind cycle, we find that this non-linear behavior causes reversing dunes to migrate against the resultant transport direction. This migration reflects the difference in dune slope seen by irregular storm events blowing to the east and the westward wind of the daily cycle. Thus, we explore the impact of extreme events on dune morphodynamics and examine new aspects of the permanent feedback between dune topography and wind speed. We conclude that transient behaviors associated with crest reversals contribute to the observed diversity of dune patterns, even within the same area for dunes of different sizes.

Gao, X., Narteau, C., & Gadal, C. (2021). Migration of reversing dunes against the sand flow path as a singular expression of the speed-up effect. Journal of Geophysical Research: Earth Surface, 126, e2020JF005913. https://doi. org/10.1029/2020JF005913.
The influence of pore gas pressure and gas permeability on rainfall infiltration 
Authors: Tian Wenjing , Peiffer Herman , Malengier Benny
Published: March 2022

Rainfall infiltration is a significant trigger that lead to slope failures. The change of pore gas pressure caused by rainfall infiltration plays an important role in the slope stability. The purpose of this research is to examine the important effect of the pore gas and the gas permeability in the process of rainfall infiltration. Firstly, Water-air-two phase flow analysis were adopted as to analyze the movement of water and gas in the process of rainfall infiltration. In order  to evaluate stability of slope, the pore gas pressure could be considered as a external load variable to incorporate in the thrust residual method which is a traditional method to evaluate slope stability. The result showed that safety factor decreased over the time when adding pore gas pressure into slope stability method compared to not consider the gas pressure, this is mainly because the pore gas pressure gradient was formed and the pore gas pressure is an important factor in the infiltration of slope stability. In addition, a numerical soil column model with the finite element method has been established for examining the effects of pore gas pressure and gas boundary condition on the rainfall infiltration. After giving the same initial conditions, the soil column under various gas permeable conditions is simulated then the influence of gas boundary permeability on infiltration intensity, pore gas pressure were also analyzed. The result showed that there is a highly relevant relationship between infiltration intensity and gas permeability on the boundary. The stable infiltration intensity is sensitive and it decreases quickly when the gas boundary permeability is at lower stage. As gas boundary permeability going up, this sensibility is declined gradually. The relationship between the infiltration intensity and gas boundary permeability can be regressed to be logarithmic. Furthermore, with the increase of gas boundary permeability, the pore gas pressure increases nonlinearly and the movement  of wetting front slows down.
 Artificial neural network models applied to olive tree phenology in Italy reveal daily insolation control of budbreak 
Authors: Cagnarini Claudia , Gnecco Giorgio , Salimonti Amelia , Zaffina Francesco , Samad Nafeesa , Chiriacò Maria Vincenza
Published: March 2022

Olive (Olea europaea L.) trees are traditionally cultivated in the Mediterranean basin, providing both healthy food and ecosystem services, such as climate change mitigation and soil erosion control, particularly in arid areas. Despite its importance, olive phenology, as impacted by climate change, is under-studied. To tackle this gap, we assessed the potential of feed-forward artificial neural network models to predict five main olive phenophases (apex budbreak, inflorescence, flowering, pit hardening and olive maturation index 1) at their onset for cultivars ‘Picholine’, ‘Carolea’ and ‘Coratina'. The dataset was collected from seven sites across Italy during the years 1997-2000.  Due to gaps in the dataset, the models were initialized by supervised training with the subset of full phenological observations, followed by semisupervised training based on the full dataset and iterative estimations of the missing observations. The softmax activation function was used in the output layer by interpreting the incremental phenological transitions as proportional to probabilities. The networks with at least four hidden layers activated by the sigmoid function and trained with the momentum method and linearly-decreasing parameters were best performing (validation RMSE of 15.5 d and 17.1 d for ‘Picholine’ and ‘Carolea’, respectively). Daily insolation consistently improved budbreak prediction with respect to daily mean temperature, suggesting the operation of photoreceptor activation mechanisms. Inflorescence was better predicted when daily minimum temperature was added, consistent with a chilling-warm requirement mechanism. Flowering was less consistent, but mean temperature was a primary controlling cue. Therefore, each phenophase is likely controlled by different climate cues. When tested on two independent flowering dates in 2017 and 2018 from one of the sites , the best performing models for each cultivar gave median errors of 4.3 d, 12.1 d, 7.4 d and 3.7 d for the ‘Picholine’, ‘Carolea’, ‘Coratina’ and the combinaed ‘Picholine+Carolea+Coratina’, respectively. The worse predictions for 'Carolea' is likely due to the hypothesized sensitivity of this cultivar to climate change, that occurred in the years between the training and the testing observations. Therefore, the olive sensitivity to climate change could be strongly cultivar-dependent, which calls for more in-depth investigation in the future. The calibrated models can be used both as operational and hypothesis-testing tools to study climate change effects on olive phenology. 
Small scale changes superimposed on larger scale sea level-induced changes in cores from the Nordkapp Basin. 
Authors: Sandvold Maren , Felix Maarten
Published: March 2022

The Nordkapp Basin is located in the southwest Barents Sea. It was formed by rifting in the late Palaeozoic. As the area containing the basin moved north from the equator the climate changed from warm and arid to temperate and humid. Initially a large carbonate platform developed in the Barents Sea in the Carboniferous and Permian. The change in climate due to northward drift caused the platform to shift from a carbonate to clastic platform at the end of the Permian. The sea level changed several times during the Mesozoic due to a combination of eustatic changes and salt diapirism. The depositional environment in the area had been interpreted from multiple cores to vary from onshore coastal plain and delta plain to shelf environment due to the large scale sea level changes. In this work, the cores have been revisited to study smaller scale changes within the environments that had been recognised but not described extensively. The nature of small scale changes is different in different environments and can be seen in different aspects like the bioturbation intensity and clay and sand content. This work will compare the smaller scale sea level changes across the different environments encountered in the cores.

 
Metasomatic aureoles of highly mobile elements related to evolved granitic aplite-pegmatites from Fregeneda–Almendra (Spain–Portugal)
Authors: Errandonea-Martin Jon , Garate-Olave Idoia , Roda-Robles Encarnación , Cardoso-Fernandes Joana , Lima Alexandre , Ribeiro Maria dos Anjos , Teodoro Ana Cláudia
Published: March 2022

Granitic pegmatites represent an important source of numerous critical raw materials, and subsequently, the exploration of new deposits has become a crucial objective in the energy transition towards green technologies. Systematic studies of geochemical aureoles related to late-Variscan Lithium-Cesium-Tantalum (LCT) pegmatites at the Fregeneda–Almendra Pegmatite Field (Central Iberian Zone; Iberian Massif), have provided valuable information to consider in mineral exploration. Due to the relative homogeneity of host psammitic and pelitic metasediments (SiO2/Al2O3 of 2.57–5.59 wt.%, and Fe2O3t/K2O values of 0.24 to 4.19 wt.%), it has been possible to establish an ideal composition for the country rocks to assess the chemical behavior of some key elements associated to the studied LCT pegmatites.

The performed geochemical modelling (based on Gresens’ (1967) equation) shows that the intrusion of evolved aplite-pegmatites (Li-mica- and spodumene-bearing) produced an enrichment in the host rocks of several elements defined as highly mobile (F, B, Li, Rb, Cs, Sn, Be and Tl) in comparison with the determined immobile elements (Si, Al and Ti). Calculated gains and losses of such highly mobile elements display exponential decreasing trends according to the distance from the pegmatitic dyke, with Li and Cs reaching furthest from the dykes (first evidence of anomalous contents starting at distances of 4–5 times the thickness of the dyke). In terms of mineral exploration, the extent of such aureoles associated with potentially economically interesting dykes may be traceable by different small-footprint exploration tools as remote sensing, X-Ray Fluorescence, or Laser-Induced Breakdown Spectroscopy (LIBS).

Gresens, R. L. (1967). Composition–volume relationships of metasomatism. Chemical Geology 2, 47–55.

Financial support: European Commission’s Horizon 2020 Innovation Programme [grant agreement No 869274, project GREENPEG: New Exploration Tools for European Pegmatite Green-Tech Resources]
Cost-effective GNSS sensors applied for crustal deformation purposes: insights from an experiment in NE-Italy
Authors: Tunini Lavinia , Zuliani David , Magrin Andrea
Published: March 2022

The global data coverage of the Global Navigation Satellite Systems (GNSS) provides a fundamental and unique dataset for a wide range of applications, such as crustal deformation, topographic measurements, or near surface processes studies. However, a strong limitation is represented by the high costs of the GNSS receivers and the supporting software, which make them available only by the scientific communities capable of affording them. The GNSS technology has been continuously and rapidly growing and, in recent years, new cost-efficient (low-cost) instruments have entered the mass market, gaining the attention of the scientific community for potentially being high-performing alternative solutions. In this study, we matched in parallel a dual-frequency cost-effective receiver (u-blox ZED F9P) and two high-cost receivers, all connected to the same geodetic-class antenna. We tested the system by processing the data together with the observations coming from a network of GNSS permanent stations operating in North-East Italy. We compare the time-series obtained using cost-effective geodetic equipment with those obtained using geodetic-class instruments. We show that mm-order precision can be achieved by cost-effective GNSS receivers, while the results in terms of time series are largely comparable to those obtained using high-price geodetic receivers.
A novel, Copula-based approach for the bias correction of daily precipitation: a case study in the eastern Mediterranean
Authors: Lazoglou Georgia , Zittis George , Bruggeman Adriana
Published: March 2022

Climate model output is widely used as input to impact models. Such applications include hydrological, crop, energy modeling, and more.  However, due to model deficiencies and the stochastic nature of climate processes, some variables (e.g., daily precipitation) tend to present systematic biases and deviations from the observed conditions. This is particularly important when studying high-impact extreme events. The present study aims to develop a Copula-based method for bias-correcting modeled daily precipitation. Precipitation data are provided by two EURO-CORDEX regional climate models (KNMI-RACMO22E and CLMcom-CCLM4) and for two time periods (1981-2010 and 2031-2060). The demonstration area is the island of Cyprus, located in the eastern Mediterranean climate change hot-spot. Cyprus is characterized by a complex coastline and steep orography that drive the precipitation distribution. As a reference dataset, we used a high resolution (1x1km) gridded observational dataset, derived from a dense network of stations. For this application, we developed a copula-based structure scheme between the reference and the simulated data sets. This was for the historical period and each model grid cell. Then, assuming this relation remains unchanged, we corrected the biases for both study periods (historical and near future). Due to the stochastic nature of precipitation, the copula schemes were developed separately for each hydrological season (i.e., wet: November to March and dry: April to October). In addition, different copula schemes were developed for non-extreme and extreme events. The results showed that the proposed method could significantly improve the modeled precipitation for both models in 85% and 92% of grid cells, respectively. These improvements are evident throughout the year and for both extreme and non-extreme values. The climate change signal (precipitation decline near 7%) remains unchanged after applying the bias correction.
A comparison study between linear detrending and recursive digital filter in aerosol deposition velocity evaluation by eddy covariance method 
Authors: Pappaccogli Gianluca , Donateo Antonio , Famulari Daniela
Published: March 2022

In the last decades, ecosystem activities are continuously monitored at long-term eddy covariance (EC) research infrastructures located worldwide, in order to estimate turbulent exchanges at the land-atmosphere interface, which plays a key role in many applications. In this context, the eddy covariance technique represents the reference method for the estimation of direct aerosol turbulent exchanges. In this study, the performance of Linear Detrending (LDT) and a Recursive Digital Filter (RDF) in removing the low-frequency contribution to the calculations of aerosol vertical turbulent fluxes is investigated. The both methods are applied in order to obtain a correct evaluation of ultrafine particles, exchange velocity, separating the negative cases (named emission velocity - Ve) from positive cases (the so called deposition velocity - Vd). An ogive analysis of turbulent fluxes was carried out in order to obtain the low-frequency time scales (τc) required by the RDF for different atmospheric stability conditions (i.e. unstable, stable and neutral). RDF was applied also with a constant low-frequency time scale (RDF300, τc=300s). In this comparison study LDT has been used as method of reference. Stationarity test proposed by Mahrt (1998 - MST98) has been applied particle number fluxes with and without applying LDT and RDF methods, in order to investigate the impact of separation criteria on stationarity test performances. The novelty of this work consists in the straightforward application of the recursive digital filter to real long-case EC measurement of particle number concentration flux, assessing the performance of the two filtering methodologies, which can be applied in real-time and post-processing automated procedures. Results show that there are no significant differences in stationary cases for filtering procedures. The sensitivity analysis carried out for the main turbulent parameters highlights that wider discrepancies occur between LDT and RDF300, showing a large increase in turbulent number particles flux.  Filtering procedures lead a slight increase of exchange velocity, although and underestimation occurs for emission and deposition velocities. The filtering effect of RDF manuscript strongly depends on the low-frequency time scale, which should be preferably estimated by means of spectral criteria.
The Interplay between Zonal Winds and Magnetic Fields in Uranus and Neptune
Authors: Soyuer Deniz , Helled Ravit
Published: March 2022

Uranus and Neptune exhibit strong zonal winds reaching up to 200 m/s and 400 m/s relative to their assumed bulk rotation, respectively. Furthermore, recent studies show that planetary ices such as water and ammonia become ionically conducting under conditions present in the ice giants. With rapidly increasing electrical conductivity, zonal flows inevitably couple to the background magnetic field, inducing electrical currents and magnetic field perturbations spatially correlated with zonal flows. Induced currents generate Ohmic dissipation, which can be used to constrain the depth of the zonal winds via the energy/entropy flux throughout the planetary interior. Constraining the zonal wind decay can be used to estimate the strength of magnetic field perturbations. Flows coupled to the background magnetic field induce poloidal and toroidal field perturbations through the ω-effect. Toroidal perturbations are expected to diffuse downwards and produce poloidal fields through turbulent convection, which are comparable to those induced by the ω-effect.We present a method for calculating electrical conductivity profiles of ionically conducting H-He-H2O mixtures using results from ab-initio simulations. We then apply this prescription on several published interior structure models of Uranus and Neptune, assuming the heavy elements are represented by water. Structure models with higher water abundances (hot models) also have larger electrical conductivity values and their zonal winds need to decay faster compared to colder models. Using our solutions for the zonal wind decay, we estimate the strength of magnetic field perturbations induced by the zonal flows. We find that colder models could potentially have poloidal field perturbations that reach up to O(0.1) of the background magnetic field in the most extreme case. The possible existence of poloidal field perturbations spatially correlated with zonal flows could be used to constrain the interior structure of Uranus and Neptune.
Towards an international standard for the precise determination of physical heights
Authors: Sanchez Laura , Huang Jianliang , Barzaghi Riccardo , Vergos Georgios S.
Published: March 2022

Measuring, studying, and understanding global change effects demand unified geodetic reference frames with (i) an order of accuracy higher than the magnitude of the effects to be observed, (ii) consistency and reliability worldwide, and (iii) long-term stability. The development of the International Terrestrial Reference System (ITRS) and its realisation, the International Terrestrial Reference Frame (ITRF), enable the precise description of the Earth’s geometry by means of geocentric Cartesian coordinates with an accuracy at the cm-level and with global consistency. An equivalent high-precise global physical reference system that provides the basis for the consistent determination of gravity field-related coordinates worldwide, in particular geopotential differences or physical heights is missing. Without a conventional global height system, most countries are using local height systems, which have been implemented individually, applying in general non-standardised procedures. It is proven that their combination in a global frame presents discrepancies at the metre level. Therefore, a core objective of the international geodetic community is to establish an international standard for the precise determination of physical heights. This standard is known as the International Height Reference System (IHRS). Its realisation has been a main topic of research during the last years. Recent achievements concentrate on (1) compiling detailed standards, conventions, and guidelines for the IHRS realisation, (2) evaluating computational approaches for the consistent determination of potential differences, and (3) designing an operational infrastructure that ensures the maintenance and long-term stability of the IHRS and its realization. This contribution summarises advances and current challenges in the establishment, realization and sustainability of the IHRS.
Natural variability in air–sea gas transfer efficiency of CO2 
Authors: Yang Mingxi , Smyth Timothy , Kitidis Vassilis , Brown Ian , Wohl Charel , Yelland Margaret , Bell Thomas
Published: March 2022

The flux of CO2 between the atmosphere and the ocean is often estimated as the air–sea gas concentration difference multiplied by the gas transfer velocity (K660). The first order driver for K660 over the ocean is wind through its influence on near surface hydrodynamics. However, field observations have shown substantial variability in the wind speed dependencies of K660. During a ~ 11,000 km long Southern Ocean transect, we measured K660 with the eddy covariance technique.  In parallel, we made a novel measurement of the gas transfer efficiency (GTE) based on partial equilibration of CO2 using a Segmented Flow Coil Equilibrator system. GTE varied by 20% during the transect, was distinct in different water masses, and related to K660. At a moderate wind speed of 7 m s−1, K660 associated with high GTE exceeded K660 with low GTE by 30% in the mean. The sensitivity of K660 towards GTE was stronger at lower wind speeds and weaker at higher wind speeds. Naturally-occurring organics in seawater, some of which are surface active, are likely the cause of the variability in GTE and in K660. To investigate this further, we perform further laboratory experiments to assess the effects of surfactant concentration and water temperature on GTE.
Metabolic Signatures of an Aerial Biosphere in the Clouds of Venus: A Self-Consistent Photo-Bio-Chemical Model
Authors: Jordan Sean , Shorttle Oliver , Rimmer Paul
Published: March 2022

Life in the clouds of Venus, if present, has been proposed to extract energy from its environment using sulfur-based metabolisms. These metabolisms link life to the chemistry of Venus's atmosphere and thus provide testable predictions of life's presence given current observations. In particular, these hypothetical metabolisms raise the possibility of Venus's enigmatic cloud-layer SO2-depletion being explained by life. We couple each proposed metabolic pathway to a photochemical-kinetics code and self-consistently predict the composition of Venus's atmosphere under the scenario that life produces the observed SO2-depletion. Using this photo-bio-chemical kinetics code, we show that all three metabolisms produce SO2-depletions which violate other observational constraints on Venus's atmospheric chemistry. For each metabolism, we estimate the maximum potential biomass density in the cloud layer before the observational constraints are violated. Our analysis shows that either the observed SO2-depletion is due to a currently unknown metabolism, or there is not a high-mass biosphere in Venus's clouds. The methods employed are equally applicable to aerial biospheres on Venus-like exoplanets, planets that are optimally poised for atmospheric characterisation in the near-future.
Fibre-Optic Sensing for Volcano Monitoring on Grímsvötn, Iceland
Authors: Klaasen Sara , Thrastarson Sölvi , Çubuk-Sabuncu Yeşim , Jónsdóttir Kristín , Gebraad Lars , Fichtner Andreas
Published: March 2022

We present the results of an experiment with Distributed Acoustic Sensing (DAS) on Grímsvötn in Iceland. DAS is a novel detection method that samples the strain wavefield due to ground motion along a fibre-optic cable with high temporal (kHz) and spatial (m) resolution. Consequently, it has the potential to increase our understanding of physical volcanic processes.

 

We deployed a 12 km long fibre-optic cable for one month (May 2021) on Grímsvötn, Iceland’s most active volcano, which is completely covered by the large Vatnajökull ice sheet. The cable was trenched 50 cm into the ice, following the caldera rim and ending near the central point of the caldera on top of a subglacial lake. A large number of hammer blow experiments allow us to estimate the Rayleigh wave dispersion curves, and thickness of the ice layer on top of the volcanic rock.

 

We have discovered previously undetected levels of seismicity, with up to several hundreds of local events per day, using an automated earthquake detection algorithm that is based on image processing techniques. First arrival picks are identified with an automated cross-correlation based algorithm, developed specifically for complex and local events recorded with DAS. The first arrival times, combined with a probabilistic interpretation and the Hamiltonian Monte Carlo algorithm, allow us to estimate event locations and their respective uncertainties, even in the absence of a detailed velocity model. The detection and localisation of the recorded events paints a differentiated picture of Grímsvötn’s volcano-seismicity.

 

The preliminary results of our experiment highlight the potential of DAS for studies of active volcanoes covered by glaciers, and we hope that this research will contribute to the fields of volcano monitoring and hazard assessment.
On the Challenge of Convection Permitting Precipitation Simulations: Results from Idealised Experiments
Authors: Ahrens Bodo , Leps Nora
Published: March 2022

Limited-area convection-permitting climate models (CPMs) with horizontal grid-spacing less than 4km and not relying on deep convection parameterisations (CPs) are being used more and more frequently. CPMs represent small-scale features such as deep convection more realistically than coarser regional climate models (RCMs) with deep CPs. Because of computational costs CPMs tend to use smaller horizontal domains than RCMs. As all limited-area models (LAMs), CPMs suffer issues with lateral boundary conditions (LBCs) and nesting. We investigated these issues using idealised Big-Brother (BB) experiments with the LAM COSMO-CLM. Grid-spacing of the reference BB simulation was 2.4 km. Deep convection was triggered by idealised hills with driving data from simulations with different spatial resolutions, with/without deep CP, and with different nesting frequencies and LBC formulations. All our nested idealised 2.4-km Little-Brother (LB) experiments performed worse than a coarser CPM simulation (4.9km) which used a four times larger computational domain and yet spent only half the computational cost. A boundary zone of >100 grid-points of the LBs could not be interpreted meteorologically because of spin-up of convection and boundary inconsistencies. Hosts with grid-spacing in the so-called grey zone of convection (ca. 4 - 20km) were not advantageous to the LB performance. The LB's performance was insensitive to the applied LBC formulation and updating (if smaller or equal 3-hourly). Therefore, our idealised experiments suggested to opt for a larger domain instead of a higher resolution even if coarser than usual (~5km) as a compromise between the harmful boundary problems, computational cost and improved representation of processes by CPMs.
Using Vertical Integrated Liquid Density from a Weather Radar Network to Nowcast Severe Events
Authors: Esbrí Laura , Rigo Tomeu , Llasat M. Carmen , Parodi Antonio
Published: March 2022

This contribution has the main goal of identifying, characterizing, tracking and nowcasting severe thunderstorms using the Density of the Vertical Integrated Liquid (DVIL). The DVIL can synthesize all the volumetric information of a column of the weather radar in a 2D plane. This is, it estimates the quantity of precipitable liquid water in the column but, besides, it reduces the dependency on the height of the column. This point becomes crucial to give an appropriate weight of potential danger to thunderstorms that occurred out of the typical convective season. . This is particularly useful to improve the decision-making and early warning in critical environments and infrastructures, like airports and air traffic management (ATM). The usage of DVIL has multiple advantages, for instance, reducing the computational time consumed on the analysis of large areas. Also, to obtain a good and simple description of the potentially dangerous thunderstorms, and to have an easily integrating into other systems for ATM decision making. The main disadvantage is a less precise characterization of the atmospheric objects than with the whole radar volumetric data. Nevertheless, the differences are scarce and do not produce any significant inconvenience in the procedure. The algorithm first identifies those areas exceeding a DVIL threshold, which is established for thunderstorms with a certain probability of producing severe weather. The characterization module turns out simpler than in other methodologies because of the data type (2D instead of 3D reflectivity fields), but it can be combined with other data types if needed. The tracking and nowcasting procedure obtain the past trajectory of the thunderstorm and then use it to weather forecast from 5 to the next 60 minutes, with 5 minutes steps. Different convective episodes that have affected the proximity of Italian and Spanish airports have been analysed to evaluate the following points: (1) the performance of the correct identification of potentially dangerous thunderstorms, (2) the capability of tracking the path and characterizing the life cycle of those storms, and (3) the ability of the nowcasting to correctly forecast the time and the most dangerous area.

This project has received funding from the SESAR Joint Undertaking under grant agreement No 892362, SINOPTICA-H2020 (Satellite-borne and IN-situ Observations to Predict the Initiation of Convection for Air traffic management) project.
Quantifying Holocene Accumulation Rates from Ice-Core Dated Internal Layers from Ice-Penetrating Radar Data over the West Antarctic Ice Sheet
Authors: Bodart Julien , Bingham Robert , Young Duncan , Blankenship Donald , Vaughan David
Published: March 2022

Modelling the past and future evolution of the West Antarctic Ice Sheet (WAIS) to climate and ocean forcing is challenged by the availability and quality of observed palaeo boundary conditions. Aside from point-based geochronological measurements, the only available proxy to query past ice-sheet processes on large spatial scales is Internal Reflecting Horizons (IRHs) as sounded by ice-penetrating radar. When isochronal, IRHs can be used to determine palaeo-accumulation rates and patterns, as previously demonstrated using shallow, centennially dated layers. Whilst similar efforts using deeper IRHs have previously been conducted over the East Antarctic Plateau where ice-flow is slow and ice thickness has been stable through time, much less is known of millennial-scale accumulation rates over the West Antarctic plateau due to challenging ice dynamical conditions in the downstream section of the ice sheet. Using deep and spatially extensive ice-core dated IRHs over Pine Island and Thwaites glaciers and a local layer approximation model, we quantify Holocene accumulation rates over the slow-flowing parts of these sensitive catchments. The results from the one-dimensional model are also compared with modern accumulation rates from observational and modelled datasets to investigate changes in accumulation rates and patterns between the Holocene and the present. The outcome of this work is that together with present and centennial-scale accumulation rates, our results can help determine whether a trend in accumulation rates exists between the Holocene and the present and thus test to what extent these glaciers are controlled by ice dynamics rather than changes in accumulation rates.
Multiorder Hydrologic Position for Europe (EU-MOHP) as a Set of Environmental Predictor Variables for Hydrologic Modelling and Groundwater Mapping with Focus on the Application of Machine Learning
Authors: Nölscher Maximilian , Mutz Michael , Broda Stefan
Published: March 2022

The application of machine learning in geosciences began several decades ago and is, especially in the advent of increasing and affordable computational power, continuously gaining popularity. However, in some specific areas such as hydrogeology, where processes are partly or fully subsurface, the application of machine learning is still limited due to either missing or noisy data, such as in mapping hydrogeochemical parameters of aquifer properties. The presented dataset EU-MOHP v013.1.0 partly closes this gap. It provides cross-scale information on the multiorder hydrologic position (MOHP) of a geographic point within its respective river network and catchment as gridded maps. More precisely, it comprises the three measures “lateral position” (LP) as a relative measure of the position between the stream and the catchment divide, “divide stream distance” (DSD) as sum of the distances to the nearest stream and divide and “stream distance” (SD) as an absolute measure of the distance to the nearest stream. These three measures are calculated for several hydrologic orders to reflect different spatial scales. Its spatial extent covers major parts of the European Economic Area (EEA39), which also largely coincides with physiographical Europe. Although there might be many potential use cases, this dataset serves predominantly as valuable static environmental predictor variable for hydrogeological and hydrological modelling such as mapping or regionalization tasks using machine learning. The concept is strongly inspired by Belitz et al. (2019), who generated this dataset for conterminous USA.
Natural and anthropogenic factors shaping the shoreline of Klaipeda, Lithuania
Authors: Kondrat Vitalijus , Sakurova Ilona , Baltranaite Egle , Kelpsaite-Rimkiene Loreta
Published: March 2022

Port of Klaipeda is situated in a complex hydrological system, between the Curonian Lagoon and the Baltic Sea, at the Klaipeda strait in the South-Eastern part of the Baltic Sea. It has almost 300 m of jetties separating the Curonian Spit and the mainland coast, interrupting the main path of sediment transport through all South-Eastern coast of the Baltic Sea. Due to the Port of Klaipeda reconstruction in 2002 and the beach nourishment project, which was started in 2014, the shoreline position change tendency was observed. Shoreline position measurements of various periods can be used to derive quantitative estimates of coastal processes direction and intensity. This data can be used to further our understanding of the scale and timing of shoreline changes in a geological and socio-economic context. This study analyzes long and short-term shoreline position changes before and after the Port of Klaipeda reconstruction in 2002. Positions of historical shorelines from various sources were used, and the rates (EPR, NSM, and SCE) of shoreline changes have been assessed using the Digital Shoreline Analysis System (DSAS). An extension of ArcGIS. K-means clustering was applied for shoreline classification into different coastal dynamic stretches. Coastal development has changed in the long-term (1984–2019) perspective: the eroded coast length increased from 1.5 to 4.2 km in the last decades. Coastal accumulation processes have been restored by the Port of Klaipeda executing the coastal zone nourishment project in 2014.
Surface geostrophic currents derived from the nonlinear diffusion filtering of the GOCE-based satellite-only MDT using the geodesic mean curvature flow
Authors: Čunderlík Róbert , Kollár Michal , Mikula Karol
Published: March 2022

We present nonlinear diffusion filtering of the GOCE-based satellite-only mean dynamic topography (MDT) based on the geodesic mean curvature flow (GMCF). GMCF represents a curvature-driven diffusion filtering, where the processed data are considered as a set of specific contour lines. A properly designed evolution of these contour lines corresponds to smoothing of the processed data. A main advantage is an adaptive smoothing of the contour lines while respecting significant values of gradients. This property can be beneficial for filtering the MDT models since it allows preserving important gradients along main ocean surface currents. We present numerical solution of the GMCF-based diffusion partial differential equations using the finite volume method (FVM) on regular grids. The derived numerical scheme is applied for filtering the satellite-only MDT models obtained as a combination of the DTU21_MSS model and the recent GOCE-based satellite-only global geopotential models. Then the filtered MDT models are used to derive velocities of the surface geostrophic currents over oceans.
Brine Vs Marine Water as Sources of Halogen-rich Hydrothermal Fluids at La Soufrière de Guadeloupe
Authors: Glynn Chagnon , Moretti Roberto , Rosas-Carbajal Marina
Published: March 2022

Abstract

The hydrothermal system of the andesitic volcano La Soufrière in the Basse-Terre island of Guadeloupe, is an ever evolving and highly dynamic system that is characterized by a variety of surface manifestations such as thermal springs, fumaroles and the Tarissan acid boiling pond (TAS) (Villemant et al.,2014). These produce halogen-rich surface emissions that makes it difficult to interpret subtle perturbations in the magmatic reservoirs using traditional geochemical and geophysical monitoring techniques (Moretti et al., 2020). A challenging situation for monitoring a volcano that has in recent history experienced six phreatic eruptions, the latest being the 1976-1977 eruptive crisis followed by a renewal of unrest in 1992 with the latest accelerated unrest episode occurring in 2018 (Komorowski et al., 2005, Moretti et al.,2020). Concurrently, TAS exhibited reduced Cl/Br ratios from ~1000 to ~300 from 18 January 2018 to 23 November 2020, suggesting marine water as a possible salinity source into the hydrothermal system. Hence, there is a critical need to fully conceptualize and appreciate the sources, full evolution and dynamic response of the hydrothermal system at La Soufrière. The research begins with investigating the potential input of ocean water into the hydrothermal system to aid in developing an exploitable geochemical database for prospective geochemical modelling analysis, leading to possible inferences on the influence of salinity on; 1) the gas-water-rock interactions in the shallow hydrothermal reservoir 2) scrubbing effects and 3) forcing conditions responsible for the measured surface gas emissions. We investigate this by numerically modelling flow transport of NaCl brines (wt.% 5, 25 and 35) using TOUGH2 software. Brines were modelled to represent volcanic- or marine- sourced brines at high temperature and pressure conditions (300°C - 350°C and 195Pa respectively). Steady state solutions of varying mass injections of orders of 1.0E-4 kg/s/m2 and 1.0E-5 kg/s/m2 resulted with the brines concentrating at heights of ~1100m a.s.l. at the summit and exiting the system, depending on the adopted permeability values. Thus implying that strong permeability contrasts due to sealing effects promoted by argillic alterations influences the trapping of brines in the upper edifice. 
Fiber hemp as a feasible crop for enhancing carbon sequestration and cultivation under water scarcity in sandy agricultural soils
Authors: Matvejeva Agne , Sut-Lohmann Magdalena , Dietrich Nils , Heinrich Martina , Raab Thomas
Published: March 2022

Extended dry periods and increasing soil degradation compel the conventional agriculture to shift towards the sustainable practices. Hemp (Cannabis Sativa L.) accounts for crops that require low agricultural inputs and has a high potential to improve soil health hence fertility. The rapid hemp growth, high biomass production and remarkably expanded rooting zone have the vast potential in carbon (C) sequestration and nitrogen (N) fixation. Hemp fibers in the European Union (EU) are commonly used for pulp and paper industry and isolation materials. The study aims to (i) analyze hemp feasibility to grow and contribute to C sequestration under the water scarce conditions in initially nutrient-poor arable sandy soil with high and low canopy densities, and (ii) assess the use of hemp residues like shives and leaves as soil amendments for oat and corn crops in order to increase soil water holding capacity and serve as a long-term nutrient supply. Hemp, oat and corn crops were grown in a greenhouse experiment under LED illumination and wind ventilation for 17 h per day until the harvest. Hemp fibers were obtained through decortication. The biomass of all crops, hemp roots separated into fine and main, soil prior and after the experiment, and soil amendments were investigated for the total C and N content with an ELEMENTAR Vario Max Cube. Also, the elemental analysis for Ca, Mg, K, Zn, Cu, Fe, Al, Na was performed using HNO3 and MP-AES analyses. Total dry root mass for oat and corn crops was measured. Additionally, the soil pH and electrical conductivity (EC) were determined. The results showed that water scarcity had hindered hemp height and biomass production. While under the water limited conditions, the low hemp canopy density had showed slightly advanced growth in comparison to the high canopy density. Furthermore, the results of oat and corn experiment indicated difference between the treatments, where the soil amendment from hemp leaves compared to hemp shives showed enhanced growth in both plant and root biomass.
Empirical stochastic modeling of observation noise in global GNSS network processing
Authors: Dumitraschkewitz Patrick , Mayer-Gürr Torsten , Strasser Sebastian
Published: March 2022

Global navigation satellite systems (GNSS) are integral to a wide array of scientific and commercial applications. Precise orbit determination of satellites in low Earth orbit relies on high-quality GNSS products. Examples of such satellites are those of the Copernicus Earth observation program of the European Union or the satellite gravimetry missions GRACE/GRACE-FO and GOCE. Numerous ground-based applications also require these products, for example: estimation of terrestrial water storage variations, earthquake monitoring, GNSS reflectometry, tropospheric and ionospheric research, surveying, or civil engineering. Furthermore, GNSS-derived station coordinates play an important role in the determination of the International Terrestrial Reference Frame. The analysis centres of the International GNSS Service (IGS) generate such products by processing observations from a global network of ground stations to one or more GNSS constellations.

So far, this kind of processing only incorporates elevation-dependent a priori modelling of observation variances and disregards temporal correlations. Meanwhile, numerous studies have shown the positive impact the incorporation of sophisticated stochastic modelling has on GNSS processing and resulting products. However, there have not been any large-scale investigations regarding the impact of stochastic modelling of observation noise on global GNSS processing.

In this contribution, we discuss a post-fit residuals approach for deriving temporal correlations in global multi-GNSS processing and their limitations. We used several years of observations and a selected IGS network of ground stations. Based on this data we analysed the post-fit residuals and the derived temporal correlations per station with respect to their seasonal effects, specific used receivers, antennas, and different transmitter signal types.
Explicit spatial modeling at the pore scale unravels the interplay of soil organic carbon storage and structure dynamics
Authors: Ray Nadja , Zech Simon , Schweizer Steffen , Bucka Franziska , Kögel-Knabner Ingrid , Prechtel Alexander
Published: March 2022

The structure of soil aggregates plays an important role for the turnover of particulate organic matter (POM) and vice versa. Analytical approaches usually do not disentangle the continuous re-organization of soil aggregates, caught between disintegration and assemblage. This led to a lack of understanding of the mechanistic relationship between aggregation and OM sequestration in soils.

In this study, we take advantage of a process-based mechanistic model that describes the interaction between the dynamic (re-)arrangement of soil aggregates, based on realistic shapes obtained by dynamic image analysis of wet-sieved aggregates, the turnover of POM, and simultaneous alteration of soil surface properties in a spatially and temporally explicit way.

We used this modeling approach to investigate the impact of the following factors for aggregation: soil texture, OM input and OM decomposition rate. Our model enabled us to quantify the temporal development of the aggregate size distribution, the amount of OC in POM fractions of different ages and the surface coverage.

The simulations provided important implications for the sequestration of OM in soils. Firstly, aggregation was largely determined by the POM input and mostly decoupled from the soil texture. Secondly, the OM storage in terms of POM increased with clay content, with both findings confirming experimental results. Thirdly, we were able to contribute to the understanding of a structural priming effect in which the increased input of POM stimulated the mineralization of old POM.