bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring Coastal Altimetry Datasets for Indonesian Seas in relation to Local Tide Gauges
Authors: Nadzir Zulfikar Adlan , Fenoglio-Marc Luciana , Uebbing Bernd , Kusche Jürgen
Published: March 2022

Satellite Altimetry has been continuously providing precise sea level for the last 28 years. However, the conventional altimetry is not at its best for the coast because it is hampered by mixed returns of electromagnetic waves due to disturbance from lands and inconsistencies of corrections. Since coastal regions are a vital part of human societies, improving methods to understand the coastal ocean topography, sea level, and its change is essential. In the last seven years alone, there are several specifically-designed coastal retracker that aimed to overcome the disturbance that occurred on the coasts. However, until now, there are only a few extensive studies have compared the accuracy and precision of retrackers and range corrections combination with regards to tide gauges on the coast of Indonesia. A region where the oceanographic condition and land and sea interaction is challenging, mainly due to the existence of shallow seas, narrow straits, and bays.

In this study, we compare sea level heights obtained using six processing schemes mostly dedicated to coastal areas. Three of them are for conventional altimetry (ALES, X-TRACK, and X-TRACK/ALES) and the other for SAR altimetry (STARS, SAMOSA++ in SARvatore and SINCS in TUDaBo). The first covers 20 years and corresponds to the repeat-track phase of Jason-1, Jason-2, and Jason-3. The second covers 10 years and corresponds to the SAR-mode measurements of Cryosat-2, Sentinel-3A/3B, and Sentinel-6. We apply similar state-of-the-art corrections designed for coastal areas.

On the other hand, a set of Indonesian tide gauge stations are being evaluated and selected in terms of their time series and their relationship with the GNSS station near it, identifying the effect of vertical land motion. Those tide gauges are considered as reference and used to assess which combination of retrackers and range corrections provide the sea level height which best agrees with in-situ data.

The results will have implications for understanding the goodness of altimetry processing schemes and of the corrections in the coastal zone, at less than 10 km. Moreover, the result is also will be used to determine precise MDT and in turn, gravity anomaly of Indonesian seas.
Assessment of soil erosion in the north flowing cratonic river basins, Peninsular India 
Authors: Kumar Rohit , Devrani Rahul , Kumar Rohitash , khiamniungan Sujang , Chatterjee Sourish , Deshmukh Benidhar
Published: March 2022

Soil erosion accelerated by climatic variation and human impact has become a severe global environmental concern. It is required to engage policymakers to limit or regulate future soil erosion rates. In the Indian subcontinent, soil erosion in mountainous terrain and ravenous land is the most severely affected. North flowing Cratonic (NFC) Rivers (total catchment area ~ 327570 sq km) in the northern Peninsular region having deeply dissected channels are usually associated with ravenous land and have been proven to be vulnerable to climate change. Due to their climatic and topographic characteristics, NFC rivers basin are expected to exhibit diverse rate of soil erosion. This study focuses on the NFC river basins, namely, Chambal (141578.12 sq km), Sindh (29041.68 sq km), Betwa (43826.4 sq km), Ken (28674.7 sq km), Tons (17172 sq km) and Son (67277.1 sq km), to assess soil erosion and spatial pattern of soil erosion prone areas by employing the widely used RUSLE model. The factors used in the RUSLE model have been derived from different sources. The annual average rainfall derived using the Center for Hydrometeorology and Remote Sensing (CHRS) data shows an increasing trend from west to east, indicating arid climate in the western and humid climate in the eastern section. The Soil erodibility (K) factor has been estimated from soil maps of the National Bureau of Soil Survey and Land Use Planning (NBSS-LUP), Nagpur. Topographic (LS) factor was derived from SRTM 30m DEM and crop management (C), and support practice (P) factors were calculated by assigning appropriate values to LULC classes created by ESRI (Environmental Systems Research Institute) using Sentinel-2 imageries at 10m spatial resolution.

Our findings show that the ravenous land in the Chambal, Sindh, Betwa and Ken river basins account for most of the high soil erosion rate in the study area. The soil loss rate increases from west to east in NFC river basins, ranging from low to extremely high. Although most of the Son river basin is covered by forest, other classes, i.e. bare land and fallow land, exhibit high erosion due to heavy rainfall. The research findings show spatial patterns of soil erosion in the NFC river basins and indicate minimal erosion in the regions of arid climates and significant erosion in the area of humid climates. Further, soil erosion hotspots identified primarily represent ravines and barren area classes. The information may be valuable to policymakers to plan for regulating future soil erosion rates in the region.

Keywords: North flowing cratonic rivers, RUSLE, Chambal River, Ravines, Soil erosion.
3D Modeling of Crust-Mantle Dynamics on Cratonic Regions: Implications for the Deformation of North China Craton
Authors: Ballı Açelya , Göğüş Oğuz , van Hunen Jeroen
Published: March 2022

A number of geological, geochemical and seismological studies suggest that cratonic lithospheres may be associated with thinning and destruction. For such unique plate configurations, the most well-known example is the North China craton. Geological studies suggest that during the Mesozoic era (120-80 Ma), a surge of magmatism occurred across the North China Craton as a response to the removal of the portions of the lithosphere beneath it. However, the question of which processes control lithospheric thinning/removal is yet to be understood. The one that is the subject of this study is the deformation controlled by gravitational instabilities (convective removal), that develop because of density variations between the lithosphere and the underlying sub-lithospheric (asthenospheric) mantle.

In accordance with numerical model predictions conceptual geological hypotheses are inferred to invoke the phase transitions in the lower crust and densification of this layer through the transformation of the basalt to eclogite during late Jurassic where Pacific flat-slab subduction led to shortening in the continental back arc (e.g Andean type tectonics). The removal event possibly occurred following the plate shortening during Early Cretaceous and various surface geological features, for instance, normal faulting/extension and pull apart basins and are interpreted in the context of coupled crust-mantle dynamics. This research aims to facilitate new 3D modelling strategies to further explain how large-scale plate geodynamics may account for the geological-geophysical fingerprints of destruction at North China Craton. The problem of deformation of the North China Craton will be approached on a much broader aspect including the extensional events that took place in Cretaceous. The overarching goal of this work is to explain the first order geodynamic mechanism that possibly constrain the craton destructions not only under North China but also other areas where such mechanism has been postulated (e.g North America, South Africa). 

 

 

 
Structural inversion of sedimentary basins: insights from 3D coupled thermo-mechanical and surface processes models and observations from the Mediterranean
Authors: Oravecz Éva , Balázs Attila , Gerya Taras , May Dave , Fodor László
Published: March 2022

A common observation in plate tectonics is the successive stages of rifting and associated crustal and lithospheric thinning, and subsequent convergence and inversion of sedimentary basins. Rates and style of inversion often vary across the sedimentary basins, influenced by changing stress and thermal fields, different convergence directions, and also controlled by inherited structures, all of which determine the localization and style of the resulting deformation. However, the dynamic feedbacks between lithospheric tectonics and surface processes, and their 3D expressions have not been studied in details by previous models, even though erosion and sediment distribution exerts a significant control on differential vertical movements and thermal evolution.

In this study, we investigate strain partitioning during extension and subsequent structural inversion, and tackle the coupling between tectonics, mantle melting and surface processes. To do so, we apply the 3D thermo-mechanical code I3ELVIS (Gerya 2015; Munch et al. 2020), which is based on staggered finite differences and marker-in-cell techniques to solve the mass, momentum and energy conservation equations for incompressible media. The models also take into account simplified melting processes, as well as erosion and sedimentation by diffusion.

We compare the modeling results with seismic and well data from the Mediterranean back-arc basins, such as the Alboran, Tyrrhenian and Pannonian Basins. The temporal variation of different plate convergence and slab retreat velocities lead to the extensional formation, recent structural inversion and related differential vertical motions of these basins. In fossil extensional basins, plate convergence has ultimately overprinted the former basin structure, and lead to the rise of young orogens, i.e. the Pyrenees or Great Caucasus.
Differential orographic impact on sub-hourly, hourly, and daily extreme precipitation 
Authors: Formetta Giuseppe , Marra Francesco , Dallan Eleonora , Zaramella Mattia , Borga Marco
Published: March 2022

Extreme precipitation in mountainous regions is the main trigger of hydrological hazards such as flash floods and debris flows, among the most dangerous natural-hazards worldwide, both for social and for economic losses. Mountains significantly influence weather and climate, including altered distribution of precipitation and of its extremes, with different impacts at different durations. Understanding the orographic impact on the statistics of precipitation extremes is therefore crucial for improving hydrological design and risk management strategies. Here, we use a novel statistical approach for the analysis of extremes based on ordinary events, which are defined as the finite independent samples of the analyzed stochastic process (e.g. Marani and Ignaccolo, 2015), to improve our understanding of the orographic impact on extreme precipitation of durations ranging between 5 minutes and 24 hours. We focus on Trentino, a rough orographic region in the eastern Italia Alps, and use data from 78 quality-controlled rain gauges with 5-minute resolution. We validated our statistical framework against statistical properties of the observed annual maxima (Nash-Sutcliffe and Bias) as well as their relation with orography. We then exploit the reduced uncertainty of this approach to quantify the orographic impact on precipitation right-tail statistics and on extreme return levels using a regression analysis. We identify two main modes of orographic relationship: a reverse orographic effect for hourly and sub-hourly durations and an orographic enhancement for durations of ~8 hours or longer. We observe that these two modes result from three main precipitation regimes, which show different proportion between extreme and very-extreme events and which emerge at very short durations mid durations and long durations. These findings are of interest for risk management applications and climate change impact studies.

References

Marani, M., & Ignaccolo, M. (2015). A metastatistical approach to rainfall extremes. Advances in Water Resources, 79, 121-126.

 
Climate and tectonic forcings driving the coastal landscape evolution: clues form late quaternary fan lobes in Kachchh region (NW India)
Authors: Srivastava Eshaan , Parrino Nicolò , Malik Javed N. , Burrato Pierfrancesco , Ghadvi MahendraSinh , Sharma Nayan , Di Maggio Cipriano , Gasparo Morticelli Maurizio , Sulli Attilio
Published: March 2022

160 km long hill ranges in the Kachchh region (NW-India) form a major E-W oriented topographic break delimiting the marshy plain of Banni in the North from the more elevated area of the Katrol Hill Range (KHR) in the south. Such topographic break is considered as the superficial expression of a quaternary active fault labelled Kachchh Mainland Fault (KMF). Numerous rivers cross this hilly region flowing roughly from South to North. The majority of those rivers are characterized by extensive fan lobes pinching out from the 200–300-meter anticlines of the hilly range.

Starting from archaeological evidence from the past 4000-5000 years, it has been inferred that an extremely fast coastal landscape evolution brought such a region to evolve from an initial gulf landform to the current setting, i.e., the marshy plains of Banni and the salt-encrusted Rann. The location of the fans lobes marked the boundary between the fluvial and marine environments.

High sedimentation rates varying between 1.1-2 mm/yr reported for the Banni plains together with historical and recent earthquakes (1668 Indus Delta, 1819 Allah Bund, 1845 Lakhpat, 1956 Anjar and 2001 Bhuj) provide valuable constraints for inferring the climatic and tectonic forcing on the region's quick dynamics.

In our ongoing work, we propose a multidisciplinary approach made by morphotectonic mapping, morphometric analyses, and geochronology to understand better how the interplay of tectonics and eustatic perturbations drove such an abrupt landscape evolution.
Estimating the viscosity of volcanic and binary melts from the vibrational properties of their parental glasses
Authors: Cassetta Michele , Di Genova Danilo , Zanatta Marco , Boffa Ballaran Tiziana , Kurnosov Alexander , Giarola Marco , Biesuz Mattia , Sorarù Gian Domenico , Giannetta Beatrice , Zaccone Claudio , Daldosso Nicola , Mariotto Gino
Published: March 2022

The knowledge of the viscosity of magmas as a function of melt composition and temperature is central in the numerical modeling of the magmatic dynamics and eruptive scenarios. Recent studies suggest that the measure of the viscosity of volcanic melts is affected by the occurrence of nano-scale modification (i.e., crystallization) of the melt structure during the measurement. This challenges the possibility of being able to quantify the crystal-free melt phase contribution to the measured viscosity. Herein we provide a new strategy that allows an accurate estimation of the melt viscosity at eruptive conditions starting from the Brillouin and Raman scattering of parental glasses. Our results show that the ratio between bulk and shear moduli and the boson peak position of glass embed the melt fragility. However, at the moment there are no known reasons why some of these quantities are linked together in such multicomponent systems. At this effort, we also provided a mean to evaluate whether the local structure of glasses may justify this correlation by testing the well-known prototypical binary system Na2O-SiO2. Concluding, our strategy allows the estimation of the melt viscosity as a function of temperature avoiding its direct measurement, ridding also the measurement from unwished crystallization.
Simulating radio propagation in ice with Parabolic Equations: applications to terrestrial glaciers and ice moons
Authors: Kyriacou Alexander , Boccarella Gianluca , Friend Pia , Helbing Klaus
Published: March 2022

We investigate the use of Parabolic Equation (PE) simulations in modelling the propagation of radio waves in inhomogeneous ice environments, such as the firn layer of terrestrial glaciers in the Alps and Antarctic. In particular PEs allow for an accurate and efficient means to simulate pulsed radar on a multi-km scale for depth-dependent permittivity profiles, and inhomogeneities that are the targets of radar scans.

PEs are an approximate solution to Maxwell's equations which are valid within a cone that is perpendicular to the source, which defines the 'paraxial direction'. For monochromatic (single-frequency) radio emission, the electric field can be solved using a numerical step-wise solver, where the next range increment can be solved from the previous step. The emission profile of the source is used to define the starting condition. To solve in the time-domain for pulses, the pulse is decomposed into its Fourier spectrum, and the electric field throughout the geometry is solved for each frequency. By sampling the frequency dependent field amplitude at a given range and depth in the geometry, one can reconstruct the pulse and measure the time of flight. We implement a two-stage PE solver which first models propagation in the forwards direction from a transmitter, and then solves in the 'backwards' direction in order to calculate reflected signals. 

We present a Python based PE solver which simulates emission from a high frequency (300 MHz to 2000 MHz) radar transmitter into ice on a multi km-scale, using depth dependent permittivity profiles and a list of objects, such as boulders, crevasses and aquifers, which cause scattering. We find that we can accurately solve pulsed radar emission, and test target reconstruction techniques. We compare radar images for targets with constant permittivity and varying permittivity. We apply our simulation method to the firn layer of numerous real-world glaciers, with their permittivity estimated from density profiles, and observed birefringence and wave-guide-like behaviour between bands of solid ice, caused by melting and refreezing of the firn. 

Additionally we apply PE simulations to assess the viability of a future melting probe mission on Saturn's ice moon Enceladus, in which the melting probe would seek a near surface water pocket, which it localized with a combined orbital and surface radar scan.
Incision and Fault slip rates along Himalayan Frontal Thrust in Nahan Salient in Northwestern Himalayas: Implications for seismic hazard assessment.
Authors: Singh Gurvinder , Thakur Mahesh , Malik Javed N
Published: March 2022

Himalayas are seismically very active regions of the world due to ongoing continent-continent collision between India and Eurasia. The Himalayas are known to have hosted deadliest earthquakes in the past century and considering the exponential growth of population in megacities of Gangetic plains, a proper seismic hazard evaluation is very critical in this region. In this regard, the present and past slip rates along the Himalayan Frontal Thrust (HFT) are very important for understanding the convergence pattern and recurrence intervals of major earthquakes. Although geodetically derived short-term convergence rates are consistence with geologically derived long-term slip rates, this correlation is based on selected studies of uplifted Holocene terraces reporting geologically derived slip rates in Central and North-West Himalayas. There is no such reporting of Geological uplift rates from Nahan Salient in NW Himalayas. We have identified uplifted and truncated quaternary terraces along HFT in Nahan Salient Northwest Himalayas through cartosat-I stereo data. We mapped and dated the uplifted terraces in order to understand the long-term convergence rates over Holocene time period. The vertical incision rates are then calculated with the help of OSL ages and height of terraces. Assuming the vertical uplift is due to repeated past earthquakes along HFT dipping at 30°, vertical uplift rates are calculated to be 2.6 mm/yr, which equates to a fault slip rate of 5.16 mm/yr and a horizontal shortening rate of 3 mm/yr. Along with that last tectonic activity along HFT is also bracketed using age of uplifted terraces and unfaulted capping units from an exposed section of HFT fault plane along river section. The OSL ages suggest that the HFT was active between 3.8±0.4Ka and 0.706±0.15Ka. Assuming that no deformation has occurred along HFT after 0.706±0.15Ka a slip deficit of 3.6 m has been accumulated which is sufficient to generate a large earthquake in the Nahan Salient NW Himalayas.
Simulation of the simplest reactor model of the dynamics of runaway electron avalanches in thunderclouds
Authors: Zemlianskaya Daria , Stadnichuk Egor
Published: March 2022

Relativistic electrons in strong large-scale thunderstorm electric fields can obtain more energy from acceleration by the electric field than they on average lose on interactions with air molecules. Such accelerating electrons are called runaway electrons. Runaway electrons can produce additional runaway electrons by Moller scattering on air molecules. In this way, runaway electrons multiply and form a relativistic runaway electron avalanche (RREA).

In strong electric fields, RREA can multiply by relativistic feedback. Infinite relativistic feedback makes avalanches self-sustaining and could hypothetically trigger a terrestrial gamma-ray burst (TGF). This report presents the results of modeling the simplest reactor - the model of the appearance of a TGF, consisting of two cells looking at each other, their comparison with theoretical calculations and previous models.  It was found that the considered model predicts lower requirements for the electric field for the appearance of TGF than the others.
Linking In-situ Magnetic and Density Structures in the Low Latitude Slow Solar Wind to Solar Origins
Authors: Woolley Thomas , Matteini Lorenzo , Horbury Timothy S. , Bale Stuart D. , Laker Ronan , Woodham Lloyd D. , Stawarz Julia E.
Published: March 2022

To date, Parker Solar Probe has completed ten solar encounters and measured a wealth of in-situ data down to heliocentric distances of ~13 solar radii. This data provides a novel opportunity to investigate the near-Sun environment and understand the young slow solar wind. Typically, the slow solar wind observed in the inner heliosphere is split into an Alfvenic and a non-Alfvenic component. The Alfvenic slow wind is thought to originate from overexpanded coronal hole field lines, whereas the non-Alfvenic slow wind could originate from active regions, transient events, or reconnection at the tips of helmet streamers. In this work, we find structures associated with non-Alfvenic slow wind in the low latitude wind measured by Parker Solar Probe. We identify at least two distinct types of structure using magnetic field magnitude, electron pitch angle distributions, and electron number density. After statistically analysing these structures, with a focus on their plasma properties, shape, and location with respect to the heliospheric current sheet, we link them to solar origins. We find structures that are consistent with the plasma blobs seen previously in remote sensing observations.
Digital Modeling of the Mechanical Processes of Hydraulic Fracturing in Poro-Elastic-Plastic Artificial Materials
Authors: Grebenshchikova Elizaveta , Nachev Victor , Turuntaev Sergey
Published: March 2022

This work presents the numerical simulation results of porous-elastic-plastic materials' mechanical behavior, reproducing the filtration-capacitance properties of reservoir rocks. The authors perform numerical modelings of laboratory experiments conducted earlier at the Sadovsky Institute of Geospheres Dynamics of the Russian Academy of Science on an installation that allows conducting studies on fracture propagation under triaxial loading conditions. This work aims to study the dynamics of fracture propagation under various loading conditions using numerical modelings. For this purpose, we take into account the porous and elastoplastic properties of the medium under study.

The authors prepared a mathematical model to study the propagation trajectory and fracture shape of hydraulic fracturing in poroelastic plastic artificial materials: set a system of defining equations and fracture criteria. Then we prepared numerical models using a mechanical software package. We built a three-dimensional numerical elastoplastic model of the rock based on the geometry of the sample. Modeling includes setting a set of mechanical parameters: Young's modulus, Poisson's ratio, internal friction angle, dilatancy angle, and deformation criterion of failure. In the study, we used a ready-made physical and mathematical mechanical model depending on the pressure of Mohr-Coulomb and pore pressure. Next, a series of numerical mechanical calculations were performed using the extended finite element method.

As a result of numerical modeling using a software package, the authors obtain that in the poroelastic model of the sample, a plasticity zone appears in the region of the central well before the fracture begins to form. Then, as the fracture spreads, the plasticity zone along the fracture propagation path is preserved. Modeling the stress-strain state along the fracture trajectory shows asymmetric distributions of stresses, pressures, and porosity relative to the central well. Different pressure values caused it in the injection and production wells used in a laboratory experiment to create pore pressure. Also, it leads to the formation of different fracture lengths towards the production and injection wells, which we see during laboratory experiments.
Arabia-Eurasia Collision and The Geodynamic Models for Plateau Uplift in Turkish-Iranian Plateau
Authors: Çetiner Uğurcan , van Hunen Jeroen , Göğüş Oğuz , Allen Mark , Valentine Andrew
Published: March 2022

Orogenic plateaux, the broad high elevation regions of Earth, are mainly formed by plate convergence/shortening and in some cases, there is (hot) mantle support for their formation. Two major examples at present are the Tibetan and Turkish-Iranian plateaux. For instance, Turkish-Iranian plateau, is a consequence of the continental plate collision between Arabia and Eurasia, which began at ~34-25 Ma and continues to the present day. The plateau can be regarded as two distinct entities, with a boundary at roughly the political border between Turkey and Iran. While there have been studies to explain the uplift history, lithospheric/crustal structure and associated magmatism, currently, the mechanisms behind the plateau growth are not well understood. The western region, also known as the East Anatolian Plateau, has a tectonic plate structure with a near-normal crustal thickness (~35-40 km) and a markedly thinned mantle lithosphere (a few 10s of km in thickness). This suggests that, to achieve its regional elevation of ~2 km there is likely considerable support from the underlying hot asthenospheric mantle. In the east, the crust of most of Iran is thicker, up to ~65 km, and it is underlain by a variable but thicker mantle lithosphere (commonly >100 km thick). It is intriguing why these two regions have similar surface elevations (2-3 km on average) and regional geomorphology, despite predicted lithospheric structures. This study will apply new class of geodynamic models to understand how such plateaux form in response to plate collision/convergence and possible mantle upwelling/support. By comparing models with different setups (varying lithospheric thicknesses, strength profiles etc.) suggested by the natural case studies, this study will provide a more general assessment of controls on plateau growth with 2-D and 3-D perspectives in the context of Arabia-Eurasia collision. Further, the study will also help to explain the role of the forces that generate dynamic topography in the evolution of such geologic structures.
Regional predictions of sub-daily rainfall extremes through data-driven blends of morphoclimatic descriptors
Authors: Magnini Andrea , Lombardi Michele , Valtancoli Elena , Castellarin Attilio
Published: March 2022

Due to the limited length of locally available sequences of precipitation extremes, estimates of design rainstorms at a given location (i.e. point rainfall depth associated with given durations and non-exceedance probabilities) are traditionally obtained from regional frequency analysis. Several statistical regionalization methods proposed in the literature enable one to exploit sequences of precipitation extremes observed at a number of sites that supposedly share the same frequency regime of rainfall extremes with the site of interest (herein also referred to as a homogeneous pooling group of sites). Homogeneous pooling groups of sites can be identified by looking at specific climatic descriptors; for instance, some reliable authors successfully utilize Mean Annual Precipitation (MAP) as the sole proxy for locally characterizing the frequency regime of sub-daily rainfall extremes and for grouping sequences of rainfall extremes records. We aim at advancing this traditional approach (1) by relaxing the hypothesis of the existence of a homogeneous pooling group of sites characterized by a unique regional parent distribution and (2) by incorporating additional morphological and climatic information in the regional model. Our research focuses on a large study area in Northern Italy, counting more than 2350 Annual Maximum Series of rainfall depth for different time-aggregation intervals between 1 and 24 hours, that have been collected between 1928 and 2011 in the Italian Rainfall Extreme Dataset (I2-RED).  We refer to local MAP value as well as to several other morphologic descriptors (e.g. minimum distance to the coast, elevation of orographic barriers, aspect, terrain slope, etc.) for characterizing the frequency regime of sub-daily rainfall extremes. We train a probabilistic neural network that uses the descriptors cited above as input layers for modeling the local frequency regime of observed rainfall annual maxima. We resort to a Generalized Extreme Value (GEV) distribution whose parameters are data-driven functions of the local morphoclimatic descriptors as well as the time-aggregation interval. We then perform a series of cross-validation experiments targeted at assessing the accuracy of the developed data-driven regional frequency model relative to a simpler regional model in which GEV parameters are functions of MAP and time aggregation intervals.

Our results address the following research problems: (a) identification of the most descriptive morphological proxies for representing the frequency regime of sub-daily rainfall extremes, (b) assessment of potential, limitations, and robustness of data-driven multivariate regional frequency models of sub-daily rainfall extremes relative to simpler and more traditional regionalization schemes.
Using small, land-based seismic arrays to monitor microseismicity induced by CO2 storage
Authors: Vescu Victor , Kettlety Tom , Kendall J. Michael , Verdon James P. , Butcher Antony , Goessen Shawn
Published: March 2022

Carbon capture and storage involves removing CO2 from industrial emissions or the atmosphere and sequestering it in a pressurised form. Onshore or offshore injection sites pump the liquefied CO2 below ground, preventing its release into the atmosphere. Earthquakes can occur when fluid is injected into a formation, inducing stress changes that can act on nearby faults, resulting in a rupture. The physics of these ruptures and the effect that fault lubrication processes have in triggering them remain key topics of research. Real-time microseismic monitoring at injection sites is the most readily available tool for painting a better picture. Injection sites on land are easier to monitor, with instruments requiring relatively little maintenance. Offshore sites, however, are more costly and less convenient because local monitoring could require expensive ocean-bottom instruments and complex deployment procedures. Induced microseismicity at CO2 injection sites is a critical measure of the reservoir and cap rock's response to injection. Thus, there is a need to locate events with low uncertainty, particularly in-depth.

There are plans for several megatonne-scale offshore CO2 injection projects around the UK. Microseismicity at these sites must be well monitored over decades to ensure long term storage security, requiring novel, cost-effective monitoring strategies. We attempt to constrain the effectiveness of small, land-based arrays that could be used to deliver relatively low-cost monitoring and map out the areas of highest risk from induced seismicity. This study compares the data of such an array installed in northwest England with the national seismic network operated by the British Geological Survey (BGS). We analyse the capability of the array to detect and locate low magnitude (M<3) seismic events. Finally, we examine how to perfect array deployment for CO2 storage monitoring by modelling the optimum size and spatial distribution of small seismic arrays.
Agricultural terraces in the Mediterranean: a multidisciplinary approach to understanding human-landscape interactions 
Authors: Srivastava Aayush , Kinnaird Tim , Turner Sam , Sevara Chris , Holcomb Justin , Lekakis Stelios , Shillito Lisa-Marie
Published: March 2022

Agricultural terraces, which demonstrate an ingenious and sustainable way of transforming hilly slopes into arable land, are widespread in Mediterranean landscapes, stretching from southern Portugal to the Judean Highlands. Despite their ecological and heritage values, there remain significant temporal and spatial gaps in understanding their histories, how they were constructed and what their socio-economic implications were for early populations. This lack of knowledge further restricts understanding the effects of terracing on landscape in terms of mitigating the impacts of past climate change and informing sustainable strategies for the future of land-management. 

To this end, we employed a multidisciplinary approach to a case study in Naxos, Greece. A GIS-based technique which uses a range of cartographic remote sensing data was employed to identify over 20 terrace sites, and trenches were hand-dug and placed in a relative chronological sequence using a portable optically stimulated luminescence (OSL) dating reader and gamma spectrometer. Samples were then collected for absolute OSL dating, micromorphology and x-ray fluorescence (XRF) analyses. Trench profiles were documented using high-resolution image-based modelling for accurate sample location and volumetric reconstruction of soil layers, and historic and modern aerial spaceborne data were used together with sample results to create models of terrace systems for spatiotemporal analyses. 

The results of this multidisciplinary approach adopted here have produced evidence of large-scale land-use in periods for which no other evidence indicative of landscape exploitation survives. A chronological framework based on over 25 OSL ages suggests terrace construction in Naxos between ~400 BC and the 16th century AD with intensification during the Medieval Greek period. Applications of soil micromorphology and XRF analyses identify key evidence of natural soil development and past land use including irrigation, soil mixing, crop residues and anthropogenic fertilisers. Modelling of terrace system development indicate their value as long-term resilient, adaptable agricultural and environmental features: where terrace systems have been maintained, reused, or abandoned under vegetation landscapes appear to maintain greater stability, retaining valuable soils and habitats compared to areas where terrace systems have been affected by overgrazing or consolidated by mechanical means. We conclude that our multidisciplinary approach has concomitant implications for the future sustainability and biodiversity of Mediterranean landscapes and beyond. 
Assessing the advantages and limitations of Coastal Depth Estimation using Machine Learning techniques
Authors: MIsra Ankita , Muslim Aidy M , Bhardwaj Shivam
Published: March 2022

Bathymetry plays an important role in ship navigation and as an input to numerical models that carry out the accurate estimation of various coastal processes such as storm surge, associated coastal flooding, and sediment dynamics like erosion-accretion of coastline. However, in-situ measurements of depths become challenging by virtue of the acquisition costs involved in deploying conventional methods, such as ship-based echo-sounding and LiDAR based techniques. Resultantly, several studies have been conducted related to Satellite Derived Bathymetry estimation using Optical Remote Sensing and empirical approaches, and most recently Machine Learning (ML) techniques. The advantage of ML methods is that they account for the non-linear relationship that exists between depths and reflectance in complex coastal environments. The present study evaluates the relative performance of 13 different linear and non-linear ML approaches, (1) Least absolute shrinkage and selection operator (LASSO) (2) Least-angle regression (LARS) (3) LASSO-LARS regression (4) Automatic relevance determination regression (ARD) (5) Bayesian ridge regression (BRR) (6) Multilayer perceptron (MLP) (7) K-nearest neighbors (KNN) (8) Support vector regression (SVR) (9) Random forest regression (RF) (10) Extra Trees regression (ET) (11) Gradient boosting regression (GBR) (2) Bagging regression (BR), for depth estimation using Landsat 8 OLI imagery in Labuan, Malaysia. The estimated depths are compared with in-situ measurements and various descriptive statistics are reported. It is observed that for all the study areas, ET, KNN, RF and BR consistently provide better results in comparison to other algorithms. The primary aim of the study is to highlight the best available ML methods that can be used with Medium Resolution satellite imagery to derive bathymetry as well as discussing the pros and cons of using ML for coastal bathymetry estimation . 
Contribution of the use of a plate model to calculate the stresses at large silicic systems
Authors: Morand Alexandra , Tait Stephen , Brandeis Geneviève
Published: March 2022

Large silicic systems can produce devastating eruptions with emitted volumes greater than 100 km³ and worldwide impacts. Such eruptions suggest the presence of significant reservoirs of silicic magma at shallow depths. Understanding how these reservoirs form is crucial to understanding how they affect the surrounding rock. But the shape and the organization of magmatic storage are still debated, despite their crucial influence on the results of theoretical predictions. Based on physical considerations of silicic-magma properties and the continental-crust state of active systems; our hypothesis is that the rise of silicic magma is stopped by the Brittle Ductile Transition. As the relaxation time of the ductile part of the crust is very short compared to the lifetime of such systems, magma storage could be considered as a buoyant liquid stored beneath an elastic plate. We thus used a plate model to theoretically predict the stress above those large magma chambers. To test our hypothesis, we computed the general behaviours of large silicic systems and compared them to natural cases. We first calculated the stress field produced in the plate. Results show that stressed values can reach tens of MPa, which is enough to cause plate failure. Then, we compared reservoir dimensions and volumes predicted by our model when failure could occur with documented ones for past eruptions. We showed that the two are consistent with each other. In a broader perspective, we then showed that stresses produced in the plate by the magma chamber can produce circular faults above the storage zone. This result has direct implications for the understanding of caldera formation during large silicic eruptions.
Detailed analysis of the Global Dimming & Brightening from 1980 to 2020 based on MERRA-2 reanalysis data
Authors: Stamatis Michael , Hatzianastassiou Nikolaos , Korras Carraca Marios Bruno , Matsoukas Christos , Wild Martin , Vardavas Ilias
Published: March 2022

The incident solar radiation on the Earth’s surface (SSR) varies on a decadal scale and this phenomenon is called Global Dimming & Brightening (GDB). GDB is known to be caused by anthropogenic and natural climate agents, with clouds and aerosols being the most significant.

This study examines the GDB using Modern-Era Retrospective Analysis for Research and Applications v.2 (MERRA-2) reanalysis data, that is originally provided on a 0.5°×0.625° horizontal grid resolution, for the 41-year period 01/1980 – 12/2020. The mean monthly SSR fluxes and their deseasonalized anomalies are computed and validated against ground truth measurements from two major reference station networks, namely the Global Energy Balance Archive (GEBA), and the Baseline Surface Radiation Network (BSRN). The changes of SSR anomalies (ΔSSR or GDB) are calculated on global (land & ocean), hemispherical and regional scales, over the entire period and for sub-periods too. In each case, it has been examined whether the sign of MERRA-2 GDB (dimming or brightening) agree or disagree with the corresponding GDB sign of stations lying within the MERRA pixel.

Using SSR deseasonalized anomalies, the computed ΔSSR for the 41-year period 1/1980-12/2019 for the Globe is equal to -6.307±0.193 W/m2 (on an annual basis), -5.716±0.281 W/m2 for the Northern Hemisphere and -6.161±0.379 W/m2 for the Southern Hemisphere, indicating an overall dimming, which has counteracted the anthropogenic greenhouse warming. Stronger dimming is found over oceans, equal to -7.805±0.244 W/m2, against a weaker dimming over land, equal to -2.582±0.249 W/m2, pointing to a less transparent atmosphere over the oceans than over land. A brightening is found over Europe and E. Asia, opposite to a dimming over India . The agreement between the estimated GDB from MERRA-2 and GEBA/BSRN stations ranges from 50% to 77%, either for the entire study period as well or the examined sub-periods (1980-1985,1986-2000,2001-2010,2011-2020), revealing a reasonable agreement adding confidence about the conclusions drawn from this MERRA-2 based analysis.
Spectroscopic and microscopic study of microbial mats in the Ojos del Salado area in Chile, a (possible) analogue environment for habitats on Early Mars 
Authors: Ehreiser Anouk , Schlarmann Leander , Strahsburger Erwin , Tavernier Adrien , Garcia Ayon , Ulloa Christopher , Foing Bernard
Published: March 2022

As much is still unknown about the conditions for life on Early Mars, extreme environments on Earth that resemble Early Martian conditions are particularly useful for planetary scientists and astrobiologists to understand Early Mars environments. As biosignatures could be preserved in the Martian mineral record, Mars analogue environments on Earth also provide useful points of reference for measurements gathered by Mars rover missions.

One of the best Martian Analogue Environments on Earth is the dry high-altitude desert in the area of the Ojos del Salado volcano in Chile. The Ojos del Salado is the highest point of the Puna de Atacama plateau in the Andes, characterized by extremely dry periglacial conditions, high UV radiation levels, low oxygen pressure, strong winds and the presence of volcanic and hydrothermal activity. High altitude lakes in the area feature polyextremophile microbial ecosystems that are adapted to these unique conditions and which provide a valuable insight into ecosystems that might resemble life on Early Mars. We report research results from Raman spectroscopy, UV-Vis spectroscopy and optical microscopy, gathered in-situ during the joint interdisciplinary Universidad de Atacama/LICA UDA/EuroMoonMars field campaign to the Ojos del Salado area in February/March 2022.
STUDY OF THE RELATIONSHIP BETWEEN THE TEMPERATURE OF THE ATLANTIC OCEAN AND HYDROLOGICAL VARIABILITY IN THE N'ZI WATERSHED (Central-North Côte d'Ivoire)
Authors: amalaman marc auriol , Mahe Gil , Tra Bi Armand Zamble , Diomande Beh Ibrahim , Rouche Nathalie , Nouaceur Zeineddine , Laignel Benoit
Published: March 2022

Summary: The decline in rainfall experienced by the West African band in the decades 70 and 80 strongly affected the flow in the various sub-catchments. In order to better identify the different modes of variability, this work is dedicated to studying the relationship between the temperature of the Atlantic Ocean and changes in flow in the N'zi watershed. Continuous wavelet analysis was used for signal search signal in the Fêtêkro (1960-1997) and N'zianouan (1960-2010) hydrometric series. As for the consistency in wavelet, it made it possible to verify the link between the flow and Atlantic Ocean temperature indices (North Atlantic Temperature: TNA and South Atlantic Temperature: TSA). Continuous wavelet analysis shows a fairly marked variability overall in high frequencies (6 months to 1 year) and interannual (> 1 year). Thus, at the Fêtêkro station north of the basin, the annual scale (1 year) records half of the variability ready with an estimated signal at 46.09%.  For the N'zianouan station, 37.18% explains the variability of the signal. At this stage, the Fêtêkro station has a rather pronounced variability to the detriment of that of N'zianouan. At the level of low frequency variability, the N'zianouan station has a fairly pronounced variability from 1 to 7 years.  Periodicity (1 – 2; 2 – 4 years) marks the highest signal (19.78%). The station of Fêtêkro shows a signal in the decade 60 estimated at 9.46% at 2-year frequency. As for wavelet consistency, it indicates a strong influence of the TSA.  index. In Fêtêkro, a consistency in phase is perceptible from 2 years in the decades 60 and 70.  At the frequency (4-8 years), this logic is observed over the entire time series. At the station of N'zianouan, we observe this reality in the decades 60 and 80 at periodicity (2-6 years), and (7-9 years) from 1990. Therefore, the results of the coherence show that the TSA index strongly impacts the flow in the N'zi watershed.

Keywords: TSA, TNA, frequency, variability, N'zi watershed

 
Identifying precursors for extreme stratospheric polar vortex events  using an explainable neural network
Authors: Wu Zheng , Beucler Tom , de Fondeville Raphaël , Székely Eniko , Obozinski Guillaume , Ball William , Domeisen Daniela
Published: March 2022

The winter stratospheric polar vortex exhibits considerable variability in both magnitude and zonal wave structure, which arises in part from stratosphere-troposphere coupling associated with tropospheric precursors and can result in extreme polar vortex events. These extremes can subsequently influence weather in the troposphere and thus are important sources of surface prediction. However, the predictability limit of these extreme events is around 1-2 weeks in the state-of-the-art prediction system. In order to explore and improve the predictability limit of the extreme vortex events, in this study, we train an artificial neural network (ANN) to model stratospheric polar vortex anomalies and to identify strong and weak stratospheric vortex events. To pinpoint the origins of the stratospheric anomalies, we then employ two neural network visualization methods, SHapley Additive exPlanations (SHAP) and Layerwise Relevance Propagation (LRP), to uncover feature importance in the input variables (e.g., geopotential height and background zonal wind). The extreme vortex events can be identified by the ANN with an averaged accuracy of 60-80%. For the correctly identified extreme events, the composite of the feature importance of the input variables shows spatial patterns consistent with the precursors found for extreme stratospheric events in previous studies. This consistency provides confidence that the ANN is able to identify reliable indicators for extreme stratospheric vortex events and that it could help to identify the role of the previously found precursors, such as the sea level pressure anomalies associated with the Siberian high. In addition to the composite of all the events, the feature importance for each of the individual events further reveals the physical structures in the input variables (such as the locations of the geopotential height anomalies) that are specific to that event. Our results show the potential of explainable neural networks techniques in understanding and predicting the stratospheric variability and extreme events, and in searching for potential precursors for these events on subseasonal time scales. 