bluuebunny/crossref_metadata_2025 huggingface dataset:
Future climate response to observed extreme El Niño analogues
Authors: Trascasa-Castro Paloma , Ruprich-Robert Yohan , Maycock Amanda
Published: February 2023

Model simulations show a robust increase in ENSO-related precipitation variability in a warmer climate, but there remains uncertainty in whether the characteristics of ENSO events themselves may change in the future. Our study aims to disentangle these effects by addressing how the global impacts of observed large El Niño events would change in different background climate states covering the preindustrial, present and future periods.Pacemaker simulations with the EC-Earth3-CC model were performed replaying the 3 strongest observed El Niño events from the historical record (1982/83, 1997/98, 2015/16). Model tropical Pacific sea surface temperature (SST) anomalies were restored towards observations, while imposing different background states, mimicking past, present and future climate conditions (following the SSP2-4.5). All variables outside the restoring region evolve freely in a coupled-atmosphere ocean transient simulation. For each start date, 30 ensemble members with different initial conditions were run for 2 years. Using this approach we ask ‘what impacts would arise if the observed El Niño occurred in the past or future’?In response to the same imposed El Niño SST anomalies, precipitation anomalies are shifted towards the Eastern equatorial Pacific in the future compared to the present day, leading to changes in the extratropical response to El Niño. Some examples are an amplification of the surface temperature response over north-eastern North America, northern South America and Australia in boreal winter. We link the changes of El Niño related tropical Pacific precipitation to a decrease in the climatological zonal SST gradient in the equatorial Pacific, as we move from past to future climatologies, which potentially leads to a higher convection sensitivity to SST anomalies over the Central and Eastern equatorial Pacific in the future. Interestingly, the simulations indicate there has already been an intensification of El Niño impacts between present day and preindustrial, which is comparable to the differences found between future and present. This nonlinear behaviour highlights the need to understand potential changes to convection thresholds in the tropical Pacific to be able to explain El Niño teleconnections under climate change scenarios. Ongoing work is exploring the changes in atmospheric circulation that lead to the overall intensification of El Niño impacts that we show in our study.
Continuous Radiocarbon Records by Laser Ablation – Status Report
Authors: Wertnik Melina , Wacker Lukas , Brehm Nicolas , Welte Caroline
Published: February 2023

The unique laser ablation (LA) setup at ETH Zurich (Switzerland), coupled to a MICADAS accelerator mass spectrometer (AMS), enables rapid 14C analyses and has been successfully employed for a broad range of carbonate archives such as stalagmites (Welte et al., 2021), otoliths (Andrews et al., 2019), and shells of Arctica islandica. An 193 nm ArF excimer laser is used to liberate CO and CO2 from the sample surface by ablation. The gas is then flushed with helium into the gas ion source of the AMS for online measurement.Advantages of the novel techniques are a significant reduction in labour-intensive sample preparation and the speed of measurement, which minimises the expensive beam-time of the AMS. However, as a transient signal is measured where each sampling location is only measured for a short duration, uncertainties associated with LA-AMS are significantly higher than for conventional measurement techniques. Still, it is possible to locate strong signals such as a growth stop or the bomb spike very rapidly and precisely using only two scans of the sample. Here we present the status of the setup and progress on data reduction aimed at reducing the larger uncertainties. Preliminary results from comparisons of parallel tracks on a stalagmite allow testing the data reduction strategy and will be shown.Andrews, A. et al. (2019), Marine and Freshwater Research, https://doi.org/10.1071/mf18265Welte, C. et al. (2021), Climate of the Past, 17(5), 2165–2177, https://doi.org/10.5194/cp-17-2165-202
Sources of Moisture to Extreme Atmospheric Rivers: a storm Denis case study
Authors: Lopez-Marti Ferran , Wu Lichuan , Messori Gabriele , Rutgersson Anna
Published: February 2023

Moisture transport within atmospheric rivers (ARs) is a complex combination of processes, with convergence of moisture with different origin and its changes over the life cycle of an AR. The water vapour budget in an AR enables us to understand the contribution of the different moisture sources and sinks (horizontal transport, local evaporation and precipitation). Here, we focus on how these contributed to the formation and development of the exceptional AR associated with storm Denis that occurred in February 2020 leading to the 3rd highest UK average daily rainfall since 18911.We use the WRF-ARW numerical limited-area atmospheric model to simulate the life-cycle of the AR in the North Atlantic basin. We use a resolution of 0.09º, and a domain covering both the AR’s formation region close to the Gulf of Mexico to the landfall region in northern and central Europe. Moreover, we performed two sets of sensitivity experiments by reducing the tropical moisture transport, and the sensible heat flux in specific areas of the oceanic basin to assess how these two main components affect the water vapour balance within the AR. We also defined a threshold to map the AR and used a centroid-based method to track its path in order to measure the shift of its location and intensity through time in the different experiments.  Our findings reveal significant relationships between the reduction of tropical moisture and a change of the location of the AR. The analysis also detected regional and temporal changes in the water vapour budget due to the perturbations done in the sensitivity experiments. In addition, relative importance of moisture sources are assessed. As such, our work provides a new case study to unravel feedback processes and the influence to the AR characteristics when perturbing the water vapour balance.
1 Davies, Paul A., et al. "The wet and stormy UK winter of 2019/2020." Weather 76.12 (2021): 396-402.
Interaction of Fully-Nonlinear Internal Solitary Waves with Cores
Authors: Lamb Kevin
Published: February 2023

Under appropriate background conditions internal solitary waves may have surface or subsurface cores. Both types of waves have been observed in the ocean. Solutions of the Dubreil-Jacotin-Long equation predict cores with closed isopycnals and, in a reference frame moving with the wave, closed streamlines. In numerical simulations of a time-evolving field these cores are unsteady and leaky: fluid is continually being entrained into the core and leaking out of the rear of the core. In this talk I will present results of the interaction of two internal solitary waves, one with a core over-taking a smaller wave without a core. In general, during the interaction the large ISW decrease in amplitude while transferring energy to the smaller ISW. During this process the large ISW loses its core and the fluid inside the core is left behind. The smaller wave grows in amplitude and forms a new core. In many cases the final small ISW is considerably smaller than the initial small ISW while the larger ISW may be larger than the iniitial ISW. ISW energy is also transferred to small amplitude internal waves. 
A new finite-difference stress modeling method governed by elastic wave equations
Authors: Fan Zhuo , Cheng Fei , Liu Jiangping
Published: February 2023

Numerical stress or strain modeling has been a focused subject in many fields, especially in assessing the stability of key engineering structures and better understanding in local or tectonic stress patters and seismicity. Here we proposed a new stress modeling method governed by elastic wave equations using finite-difference scheme. Based on the modeling scheme of wave propagation, the proposed method is able to solve both the dynamic stress evolution and the static stress state of equilibrium by introducing an artificial damping factor to the particle velocity. We validate the proposed method in three geophysical benchmarks: (a) a layered earth model under gravitational load, (b) a rock mass model under nonuniform loads on its exterior boundaries and (c) a fault zone with strain localization driven by regional tectonic loading that measured by GPS velocity field.  Because the governing equations of the proposed method are wave equations instead of equilibrium equations, we are able to use the perfectly matched layer as the artificial boundary conditions for models in unbounded domain, which will substantially improve the accuracy of them. Also, the proposed scheme maps the physical model on simple computational grids and therefore is more memory efficient for grid points’ positions not been stored. Besides, the efficient parallel computing of the finite-different method guarantees the proposed method’s advantage in computational speed. As a minor modification to wave modeling scheme, the proposed stress modeling method is not only accurate for geological models through different scales, but also physically reasonable and easy to implement for geophysicists.
Lithospheric Imaging through Reverberant Layers: Sediments, Oceans, and Glaciers
Authors: Zhang Ziqi , Olugboji Tolulope
Published: February 2023

The Earth, in large portions, is covered in oceans, sediments, and glaciers. High-resolution body wave imaging in such environments often suffers from severe reverberations, that is, repeating echoes of the incoming scattered wavefield trapped in the reverberant layer, making interpretation of lithospheric layering difficult. In this study, we propose a systematic data-driven approach, using autocorrelation and homomorphic analysis, to solve the twin problem of detection and elimination of reverberations without a priori knowledge of the elastic structure of the reverberant layers. We demonstrate, using synthetic experiments and data examples, that our approach can effectively identify the signature of reverberations even in cases where the recording seismic array is deployed in complex settings, for example, using data from (1) a land station sitting on Songliao basin, (2) an ocean bottom station in the fore-arc setting of the Alaska amphibious community seismic experiment (AACSE), and (3) a station deployed on ice-sediment strata in the glaciers of Antarctica. The elimination of the reverberation is implemented by a frequency domain filter whose parameters are automatically tuned using seismic data alone. On glaciers where the reverberating sediment layer is sandwiched between the lithosphere and an overlying ice layer, homomorphic analysis is preferable in detecting the signature of reverberation. We expect that our technique will see wide application for high-resolution body wave imaging across a wide variety of conditions.
Insights into microstructural and petrophysical properties of deformation bands in porous sandstone, Kachchh (Kutch) Rift Basin, India
Authors: Shaikh Mohamedharoon , Mukherjee Soumyajit , Dasgupta Sudipta , Rajkhowa David , Maurya Deepak , Chamyal Laxman
Published: February 2023

The study addresses how the deformation mechanisms influence the microstructural properties of deformation bands developed in high-porosity sandstones of the Kachchh (Kutch) Rift Basin (KRB), India. The KRB located at the western continental margin of the Indian plate is neotectonically active and is affected by the periodic reactivation of multiple ~W-striking dip-slip/strike-slip faults. We investigated the porous sandstones of Bhuj and Jhuran Formation, which contain cataclastic shear bands, disaggregation bands, and cementation bands. High-resolution optical and scanning electron microscopy images were used to analyze the microstructures, grain size and shape, and porosity for both the host rock and deformation bands. The cataclastic bands display preferential alignment of elongated grains parallel to the boundaries of deformation bands. The mechanisms of deformation are dominated by varying degrees of cataclasis and pressure solution that have caused grain reorganization, rolling, flaking of grain edges, and intragranular and transgranular fracturing. This resulted in grain size and porosity reduction within the deformation bands. The porosity loss in deformation bands is of three to five orders of magnitude compared to the host rock. The grain size distribution results are consistent with a power-law model that have low exponent (D) values between 0.89 and 1.00 for deformation bands. Our findings suggest that cataclasis within deformation bands appears to be dominant in the extensional stress state, however shear-related disaggregation of grains is observed in both extensional and compressional stress regimes. 
3D reconstruction of CTIDs induced by hurricane Matthew on 7 October 2
Authors: Zhai Changzhi , Chen Yutian , Zhang Shunrong
Published: February 2023

The temporal as well as vertical and horizontal variations of the concentric traveling ionospheric disturbances (CTIDs) caused by hurricane Matthew on 7 October 2016 were reconstructed using 3-dimensional computerized ionospheric tomography (3DCIT) technology, based upon the GNSS data from the dense receiver network over North America. The frequency range of disturbances was determined by spectrum analysis, and a Butterworth band-pass filter was used to de-trend the total electron content (TEC) sequences in order to determine TIDs. A remarkable CTID segment was detected at a distance of 1000 – 1500 km from the hurricane eye at ~5:40 – 6:10 UT on 7 October 2016, moving westward with the horizontal phase velocity of ~153.4 m/s, the period of ~30 min and the horizontal wavelength of ~276.1 km. The positive and negative wavefronts dominated the CITD at different times during the event. From 4:00 to 8:00 UT, the altitudinal variation of the CTIDs in electron density exhibited clear downward phase progression predominately in the range of 150 – 400 km altitudes, however, the percentage electron density disturbances were larger below 250 km. The inverted cone-like geometry of CTID wavefronts was presented. The vertical phase velocities of the CTIDs ~1100 km away from the hurricane eye in the northwest direction near 88°W, 34°N were ~203.7 – 277.8 m/s, and at the same location, the horizontal phase velocities at 300 km altitude were ~149.1 – 181.5 m/s, slightly larger than those at 200 km altitude (~145.1 – 178.5 m/s). 
Nonsmooth simulations of 3D Drucker-Prager granular flows and validation against experimental column collapses
Authors: Rousseau Gauthier , Métivet Thibaut , Rousseau Hugo , Daviet Gilles , Bertails-Descoubes Florence
Published: February 2023

Testing advanced numerical hydro-mechanical models against well-controlled experiments is a critical step in improving our understanding of unsteady granular mass flows, and necessary to provide some domains of validity for any further risk assessment.To this end, experimental granular collapses were performed to evaluate the sand6 numerical simulator introduced by Daviet & Bertails-Descoubes (2016), which represents the granular medium as an inelastic and dilatable continuum subject to the Drucker-Prager yield criterion in the dense regime, and computes its dynamics using a 3D material point method (MPM). A specificity of this numerical model is to solve such the Drucker-Prager nonsmooth rheology without any regularisation, by leveraging tools from nonsmooth optimisation.This nonsmooth simulator, which relies on a constant friction coefficient, is able to reproduce with high fidelity various experimental granular collapses over inclined erodible beds, provided the friction coefficient is set to the avalanche angle - and not to the stop angle, as generally done. The results, obtained for two different granular materials and for bed inclinations ranging from 0° to 20°, suggest that a simple constant friction rheology choice remains reasonable for capturing a large variety of granular collapses up to aspect ratios in the order of 10.Investigating the precise role of the frictional walls by performing experimental and simulated collapses with various channel widths, we find out that, unlike some assumptions formerly made in the literature, the channel width has lower influence than expected on the granular flow and deposit.The constant coefficient model is extended with a hysteresis model, thereby improving the predictions of the early-stage dynamics of the collapse. This illustrates the potential effects of such phenomenology on transient granular flows, paving the way to more elaborate analysis.
The response of the deep convection to the Antarctic Meltwater
Authors: Chen Jia-Jia , Cheng Xuhua , Swart Neil C.
Published: February 2023

Observations indicate that the mass loss from the Antarctic ice sheet has been increasing over the past several decades. This loss is projected to accelerate significantly into the future. Deep convection in the Southern Ocean is expected to bear the brunt of meltwater from a retreating Antarctic Ice Sheet. Here, we present the responses of deep convection and Antarctic Bottom Water (AABW) formation using six coupled climate models with a constant rate of freshwater flux anomaly. Six models all show a significant decrease in the strength of deep convection, albeit the magnitude and location of the changes vary greatly across models. Models that convect more strongly in the base state decrease more in deep convection. We found that the big difference in response between models is surprisingly consistent with their respective base states. With the cessation of deep convection, the AABW becomes warmer and of contraction, and the sea ice concentration and area increase significantly, accompanying surface cooling. However, the link between the responses in deep convection and sea ice area is more complicated than simply meaning more reduction in deep convection corresponds to more increase in sea ice. We suggest that this complexity is partly because some models convect over too large an area and the freshwater forcing is rather strong. Our results suggest that increasing Antarctic meltwater into the ocean will reduce AABW formation, amplifying the warming rate of deep and abyssal waters and reducing the melting rate of sea ice caused by heat input, and reducing vertical exchange due to intensified stratification.
Studying the along fault variability of slow earthquake characteristic by modeling a combined viscoelastic and damage rheology
Authors: Massoumi Sina , Dansereau Véronique , Weiss Jérôme , Shapiro Nikolai
Published: February 2023

The seismo-tectonic cycle in the subduction zones is largely controlled by the level of coupling between the sliding oceanic and continental plates that strongly varies with depth. Close to the surface, at depths of a few tens of kilometers, the plate interface remains most of time locked and is occasionally broken by large earthquakes. On the other hand, the oceanic lithosphere slips into the mantle continually at large depths. Between these two zones of locked and stable slip, the transient zone is characterized by “slow earthquakes” that are mainly manifested by episodes of silent slip and tectonic tremor that are to some degree correlated in time. Along-fault changes of the degree of inter-plate coupling are controlled by variations of the fault-zone rheology, which in turn is related by depth-dependent thermo-mechanical conditions and composition of rocks. The brittle-ductile transition and the slow earthquake cycle are often modeled with using the rate-and-state interface rheology. This empirical formulation represents the transition segment by assimilating brittle and frictional processes to the problem of a material interface friction. To this aim, a parametric model is obtained based on experimental studies of the frictional behavior of various materials at the laboratory scale. Although this framework reproduces the transition between a stick-slip cycle and the stable sliding behaviors it cannot represent steady-state relaxation processes and presents a limit to which it can be enriched to include the chemical, mineralogical and hydro-mechanical processes within faults. To overcome these limitations, we are using a modeling approach based on a continuum volumetric rheology that allow us to model physically-based variations of parameters with depth. Namely, we use a combination of viscoelastic Maxwell and damage rheologies. The resulting model is capable to take into account the localized deformations associated with quasi-brittle processes on short time scales as well as the diffuse deformations associated with the stress relaxation in the bulk of the geophysical system over long time scales. The problem is studied in two dimensions with associated boundary conditions. Along fault variations of the important controlling parameters such as the viscosity, the cohesion coefficients, and the damage recovery time are investigated in order to understand their respective contribution in the slow earthquake cycle.
Impact of the Ocean-Atmosphere coupling on extratropical cyclones around the Mediterranean basin
Authors: Chericoni Marco , Fosser Giorgia , Anav Alessandro
Published: February 2023

The Mediterranean basin is well recognized as one of the main climate change hotspots; besides, this region is one the most active cyclogenetic area of the Northern Hemisphere with a large number of intense cyclones occurring every year mainly during winter and fall. The climatology of Mediterranean cyclones has been deeply investigated in the past years, leading to a high agreement on the tracks density, seasonal cycle and favorite locations of cyclogenesis. Nevertheless, open questions still remain on the future evolution of Mediterranean cyclogenesis and associated impacts. Mediterranean cyclones typically present weaker intensities, smaller sizes and shorter lifetimes than tropical cyclones or other mid-latitude cyclones that develop over open oceans. However, they are often responsible for extreme precipitation and wind events leading to severe socio-economic and environmental impacts especially over densely populated regions and coastal areas. Thus, studying the feedbacks of air-sea interactions on Mediterranean cyclones will bring to a better understanding of both the contribution of cyclones to the variability in and extremes of the regional climate and the impacts on the marine ecosystems as well as the associated risks in maritime transportation and coastal structures.This study aims to investigate the added values of the ocean-atmosphere coupling in regional climate models in reproducing Mediterranean cyclones. To this end, two simulations are performed using the ENEA-REG regional earth system model at 12 km over the Med-CORDEX domain. The first experiment uses the mesoscale WRF model with prescribed Sea Surface Temperature (SST), while in the second WRF is coupled to the MITgcm ocean model. Different tracking methods, based on sea level pressure, are used to account for the uncertainties linked with mathematical and physical definitions of cyclone itself. The simulations are validated against ERA5 reanalysis dataset in terms of their ability to reproduce the Mediterranean cyclone climatology as well as to represent sub-daily fields linked to the cyclones (e.g. SST, heat fluxes, wind, precipitation). Here we show how the coupling of the atmosphere with an interactive ocean model affects the number of cyclones along with their intensity and duration.
Pre-Miocene Paleomagnetic Data from the Calabrian Block Document a 160° Post-Late Jurassic CCW Rotation
Authors: Siravo Gaia , Speranza Fabio , Macrì Patrizia
Published: February 2023

The Calabrian block, along with Alboran, Kabylies and Peloritani, form isolated and enigmatic igneous/metamorphic terranes (AlKaPeCa) stacked over the Meso-Cenozoic sedimentary successions of the Apennines and Maghrebides. The long-lasting debate on the origin and evolution of such crustal terranes include different paleogeographic interpretations. Some authors considered them as: i) remnants of a micro-continent lying between Eurasia and Africa; ii) fragments of the Hercynian margin of Europe separated from Africa during Early Jurassic Alpine Tethys spreading, later detached from Corsica-Sardinia and/or Catalan-Provençal margin, and then stacked over Apennine-Maghrebian sediments during Neogene roll-back episodes; iii) portion of the Africa-Adria paleomargin deformed and involved into the orogenic pile.Paleomagnetic data are crucial to properly reconstruct the drift of the AlKaPeCa blocks and their lasting geological history, however no paleomagnetic data could be obviously obtained from the Hercynian crystalline rocks of the AlKaPeCa. Besides the well-defined ∼20° clockwise (CW) rotation, constrained between 1 and 2 Ma and related to changes occurring in the roll-back system and spreading episodes in the Tyrrhenian Sea, the tectonic behavior of the Calabrian block during the Early Jurassic rifting episodes, the Early-mid Cretaceous transcurrent tectonics, the Late Cretaceous-early Cenozoic Africa-Europe collision, and Eocene-Miocene counterclockwise (CCW) 90° rotation of the Corsica -Sardinia block, to which Calabria was likely solidly attached, remains completely speculative.We report on the paleomagnetism of upper Triassic-lower Miocene sedimentary rocks from the Longobucco succession that is transgressive over the crystalline Sila Massif (NE Calabria). Well-defined remanent magnetization directions carried by hematite were isolated in 10 sites (122 samples) in Jurassic rocks. Nine Toarcian and one Tithonian Ammonitico Rosso sites yielded a dual polarity “A” magnetization component whit a direction over 40° from the geocentric axial dipole (GAD) field direction, that supports a positive fold test. Five sites yielded a “B” normal polarity component NE (<40°) of the GAD direction characterized by a negative fold test. We interpret the B component as a Miocene magnetic overprint later clockwise rotated by ∼20° during the Pleistocene (1–2 Ma) rotation of Calabria. When corrected for such rotation, the A component defines a ∼160° CCW rotation of the Calabrian block with respect to Europe. Of these, ∼90° likely occurred along with Corsica-Sardinia block during its Eocene-Miocene rotation from the Provençal margin. Thus, the Calabrian block underwent an additional Cretaceous-Eocene 70° CCW rotation that we relate to Early-mid Cretaceous >500 km left-lateral transcurrent motion between Africa and Europe.
Viscosity-reducing and Biosurfactant-producing Bacterial Consortia Isolated from Low-permeability Reservoir in Ordos Basin
Authors: Bian Ziwei , Zhi Zena , Zhang Xiangchun , Qu Yiqian , Wei Lusha , Wu Yifei , Wu Hanning
Published: February 2023

Many bacteria have been proved to change physical (viscosity, wettability, and tension), and compositions of crude oil, which can make it easier for oil to be released from rock pores and achieve the purpose of improving recovery, which is called Microbial Enhanced Oil Recovery (MEOR). Our team has previously isolated six emulsified and viscosity-reducing bacteria (Bacillus. sp.) in low permeability layers (Chang 4+5 and Chang 6) of Ordos Basin. However, environmental tolerance of the strains is limited, and the components of crude oil used by the strains were also different. The combination of strains of different species and genera may enhance the effects of single bacteria, surpass the tolerance upper limit, and optimize the viscosity reduction and degradation. Therefore, in this study, it is extremely necessary to study the bacterial consortium. Two consortia were obtained and each consortium consisted of three bacterial strains and was designated as Consortium A (51+61, 61+H-1, 51+H-1; A-ALL) and Consortium B (34(2)+42, 34(2)+A-3; 42+A-3. B-BLL). The performance of the mixed strains was evaluated by the analysis of change in emulsification rate, crude oil composition, viscosity, and the tolerance (temperature, salinity, and pH) though GC-MS, rotational rheometer, and other methods. The results showed that bacterial consortiums had higher alkali resistance and could survive temperatures of 55 °C and salinity of 50 g/L in comparison to single bacterium. The emulsification rate was 22%-48%. Consortium B has better effects than Consortium A. The viscosity reduction rate of the Consortium A after 7 days was exceeded 30% as a whole, and the rate of Consortium B was more than 35%. The crude oil of Consortium B is basically non-stick to flask. Compared with single bacteria, the utilization components of crude oil to bacteria are still different, including both long chain hydrocarbons and short chain hydrocarbons. However, the proportion of long chain n-alkanes is further reduced compared with that of single bacteria, and the highest ratio is reduced by 23.81% (B-ALL). Overall, the bacterial consortium outperforms the single strain in terms of tolerance, viscosity reduction, and degradation, which further optimizes the application of MEOR.
Loading kappa-type distributions in particle simulations
Authors: Zenitani Seiji , Nakano Shin'ya
Published: February 2023

The kappa distribution is one of the most important velocity distributions in space plasmas. It has both a quasi-Maxwellian core and a suprathermal tail, and it has been considered throughout the heliosphere and magnetospheres. Despite a strong demand for numerical studies in a kappa-distributed plasma, it is not clear how to generate kappa distributions in particle velocities in particle-in-cell (PIC) and Monte Carlo simulations. In this contribution, we present numerical procedures to generate three kappa-type velocity distributions in particle simulations.
First, we review an algorithm for the nonrelativistic kappa distribution. Mathematically, the kappa distribution is equivalent to the multivariate t-distribution [1]. A random variate following the multivariate t-distribution can be generated from the normal and chi-squared distributions. Second, we propose algorithms to generate a kappa loss-cone (KLC) distribution [2], which is often considered in the planetary magnetosphere. We have constructed two procedures. Using the mathematical properties of the beta prime distribution, we can straightforwardly generate the KLC distribution in particle simulations. Third, we propose a procedure for initializing a relativistic kappa distribution. Although the Lorentz factor makes this problem difficult, we have successfully developed a rejection-based algorithm [3]. The rejection part extends an earlier method for a relativistic Maxwell distribution [4], and it accepts particles at the rate of 95% or higher. Our method also use the beta prime distribution. As a result, we can successfully generate a power-law tail of the relativistic kappa distribution.
References:[1] R. F. Abdul & R. L. Mace, Phys. Plasmas 22, 102107 (2015)[2] D. Summers & R. M. Thorne, J. Plasma Phys. 53, 293 (1995)[3] S. Zenitani & S. Nakano, Phys. Plasmas 29, 113904 (2022)[4] E. Canfield, W. M. Howard, & E. P. Liang, Astrophys. J 323, 565 (1987)
Quinone-Mediated Electrochemical Reduction of Ferrihydrite: Effect of Sorption and Redox Potential
Authors: Li Guo-Xiang , Haderlein Stefan B.
Published: February 2023

Natural Organic Matter (NOM) shows both oxidizing and reducing capabilities through its quinone/hydroquinone functional groups and takes part in various geochemically redox reactions. Here four natural and synthetic quinone model compounds (anthraquinone-2,6-disulfonate, AQDS; anthraquinone-2-sulfonate, AQS; 2-hydroxyl-1,4-naphthoquinone, Lawsone; and anthraquinone-2,3-dicarboxylic acid, AQDC) were used to study the effect of adsorption of redox active organic matter on mediating ferrihydrite reduction. The studied quinone compounds varied regarding reduction potential and their tendency to adsorb at ferrihydrite. An electrochemical setup rather than iron reducing bacteria was used to circumvent potential inhibitory effects of the model quinones on microbial activity. Iron speciation, dissolved and adsorbed quinone concentrations and their redox state were monitored to elucidate controlling factors in mediated ferrihydrite reduction. Results show that all model quinones present at 100 µM total concentration enhanced the initial iron reduction rate of ferrihydrite, however, to very different extents. At -0.45 V (vs. Ag/AgCl) redox potential applied, the initial reduction rates increased compared to quinone free systems by factors of 62.53, 43.11, 32.26 and 2.91 for AQDS, AQS, Lawsone and AQDC, respectively. In contrast to AQDC and Lawsone, AQDS and AQS did not show significant adsorption at ferrihydrite under the conditions of our study. Due to the high sorption, the initial dissolved AQDC concentration was only 3.60 μM. The initial dissolved concentration of Lawsone was 85.70 µM and decreased further during ferrihydrite reduction. Adsorbed Fe(II) promoted the adsorption of Lawsone on ferrihydrite thereby decreasing the rate of iron reduction. Our findings demonstrate that the rate of ferrihydrite reduction correlated with dissolved quinone concentrations. As a result, AQDS and AQS showed the highest acceleration of ferrihydrite reduction. At the redox conditions applied (-0.45 V vs. Ag/AgCl) the fraction of reduced quinone species was higher for AQDS than for AQS, consistent with the higher efficiency of AQDS in mediating ferrihydrite reduction.The possibility of conducting experiments at defined redox potentials and precisely controllable experimental conditions reveals the perspectives of an electrochemical setup for the investigation of biogeochemical redox reactions.
Using the hydrological model for filling the missing discharge data by using multi-site calibration
Authors: Singh Ankit , Dhaka Hemant Kumar , Prajapati Pragati , Jha Sanjeev Kumar
Published: February 2023

The river discharge data is one of the most important pieces of information to regulate various water resources, including flood frequency analysis, drought and flood prediction, etc. The missing observer discharge data, even a short gap, influences the whole analysis and gives a totally different result. Filling data gaps in streamflow data is thus a critical step in any hydrological study. Interpolation, regression-based analysis, artificial neural networks, and modeling are all methods for generating missing data. While using the hydrological model to generate the data, we first need to calibrate the hydrological model. The single-site calibration of the hydrological model has its own limitations, due to which it does not correctly predict the streamflow at intermediate gauge locations. This is because, while calibrating the model for the final outlet, we tune the parameters that affect the results for the final outlet only and neglect the intermediate sites' output. In this study, we demonstrate the importance of multi-site calibration and use the calibrated hydrological model to generate the missing data at intermediate sites.For this study, we selected the Godavari River basin and calibrated it at the final outlet (single-site calibration) and at 18 + 1 outlets (multi-site calibration). The whole basin is divided into 103 subbasins, and the Soil and Water Assessment Tool (SWAT) hydrological model is used for this study. After the successful multi-site calibration, we generated the missing data at 25 different gauging locations. The initial results from single-site calibration (NSE (0.57) and R2 (0.61)) show good agreement between observed and simulated discharge for the final outlet. The multi-site calibration analysis is in progress, and full results will be presented at the conference.
Underground coal fires – A global post-mining catastrophe
Authors: Finkelman Robert , Dodds Henry
Published: February 2023

Uncontrolled coal fires are a universal coal mining and post-mining concern. Efforts to extinguish these fires are often unsuccessful and these fires can result in major catastrophes such as the abandonment of the town of Centralia Pennsylvania in the U.S. and displacement of many thousands of villagers in India. The physical threat of these fires, often a result of coal mining, is a serious issue that has taken the lives of people in the U.S., Asia, and Africa. However, an equally though more insidious issue is the long-term health impacts of the emissions of these uncontrolled coal fires. Recent studies in the Jharia region of India has shown that villagers living about one mile from active coal fires reported twice as many health concerns as villagers living about five miles away. Yet, there are many villages in this region and elsewhere where people are living in immediate proximity to these fires. Studies of the gases emitted from these fires and condensates formed from the escaping gases document the mobilization of potentially toxic gases such as benzene, xylene, toluene, methane, carbon monoxide and elements such as As, Se, Hg, F, Pb, Sb. An SEM/EDX study of a small (30mm X 20mm) piece of condensate collected from an active underground coal fire just meters from a village revealed several generations of deposition with at least 30 phases containing ammonia, B, F, Al, Si, S, Cl, Fe, Cu, Zn, As, Se, Br, Mo, Cd, I, Ba, Pb, and Bi. Clearly, more attention should be paid to this post mining catastrophe to minimize the health problems and deaths resulting from these uncontrolled coal fires.
Sectoral water use responses to droughts and heatwaves: analyses from local to global scales from 1990-2019
Authors: Cárdenas Belleza Gabriel Antonio , Bierkens Marc F.P. , van Vliet Michelle T.H.
Published: February 2023

Water security is threatened by a growing global population and the associated increase in sectoral water demand. This condition is worsened by the occurrence of droughts and heatwaves, which mainly lead to a reduction in the available water, increasing water scarcity. The resulting threats to water security are expected to become more pertinent when considering that such extreme events are expected to increase both in frequency and severity. Nonetheless, little is known about the responses in sectoral water use during extreme hydroclimatic events.This research therefore quantifies responses in water use for different sectors (i.e. irrigation, livestock, domestic, energy and manufacturing) during droughts, heatwaves and compound events at global, regional and local scales. To achieve this, the spatial extent, times of occurrence and durations of these hydroclimatic extremes were identified worldwide for the period 1990-2019. Next, sectoral water use responses were evaluated during these extreme events and compared to normal (non-extreme) periods for sectoral water withdrawal or consumption.Our results show that extreme events affect water use responses differently per sector and region. At a global scale, the overall use of water for domestic and irrigation sectors increased while it decreased for thermoelectric and manufacture sectors during heatwaves. Also, water use response patterns show that irrigation and domestic sectors are prioritized over livestock, thermoelectric and manufacturing on a global level. Furthermore, stronger impacts are found for heatwaves and compound events compared with impacts during droughts. Finally, our analyses show that water use drivers -such as income level, use of alternative water sources, and regulatory water policies- impact the magnitude of change in sectoral water use under these extreme events.These results set the foundation for the development of a new global sectoral water use model which will allow more accurate quantifications of sectoral water use responses and water scarcity during present and future projected droughts and heatwaves.
The CO2 storage in coal seams at the influence of coal fines migration
Authors: Wang Qian , Shen Jian , Glover Paul.W.J. , Lorinczi Piroska
Published: February 2023

Abstract: the pressure of the coal seam decays to a certain value due to the production of CH4, the production wells are switched to CO2 injection wells. The injection of CO2 can improve the CH4 recovery and realize the CO2 geological storage.The reverse migration of coal fines produced in the CH4 development stage can be caused by CO2 injection, which blocks the pore-thorats and fractures in coal seams and increases the difficulty of CO2 injection. We carried out experiments on coal fine migration and CO2 injection and storage at reservoir conditions on the simulated coal seam, which was a composite core composed of different types of coal. We focus on the migration of coal fine in simulated coal seam and the impact on CO2 storage. The experiment results show that, the permeability of the combined core, which is composed of proppant fractured coal, fractured coal and matrix coal in turn, decreases by 40.6% after being injected with 300ml of coal fine suspension with a concentration of 1g/1L. This is due to the deposition or capture of coal fines during the suspension injection, resulting in surface adsorption, bridging blockage, and direct blockage in the pore space, which seriously damaged the connectivity of the coal pore space. The proppant fractured coal can filter 77.1% of the coal fines in the suspension, and the fractured coal rock can filter the remaining 23.9% of the coal fines. The average CO2 storage capacity and CO2 storage efficiency of the composite core increased by 4.47 cm3·g-1 and 10.8%, respectively after subsequent CO2 injection into the composite core. The corresponding injection pressure difference also increased by 32.5%, and a CH4 recovery improvement of 13.6% is obtained.The migration and balockage of coal fines lead to the most significant improvement of CO2 storage in fractured coal (14.4%), followed by proppant fractured coal (10.3%), and the worst improvement of CO2 storage in matrix coal (3.4%). The migration of coal fines improves the CO2 storage effect in fractured coal seams to a certain extent, but increases the difficulty of CO2 injection, which is not conducive to the CO2 storage of the reservoir.Keywords: CO2 storage, coal seams, coal fines migration, proppant fracture
Hydrological model calibration in a Himalayan Catchment Using Remote sensing/Reanalysis Datasets.
Authors: Malla Mani Kanta , Arya Dhyan Singh
Published: February 2023

Hydrological models are simplified mathematical representations of various hydrological processes and their interactions in a catchment. They are widely employed to simulate hydrological responses under diverse scenarios of climate, land use, land cover, and agricultural and soil management practices, which are helpful for planning water resources and management at the catchment scale. The parameters of the hydrological models are often optimised by calibrating them such that the observed and simulated streamflow match closely. Reliable prediction of hydrological variables of interest in ungauged or poorly gauged basins and addressing the uncertainty associated with the prediction is a challenging task as it is very difficult to calibrate the models due to the unavailability of measured hydrological responses. Escalating research interest in predicting hydrological fluxes at ungauged or poorly gauged catchments has been witnessed recently using distributed modelling, advanced scientific methods, and the availability of high-resolution satellite-based and reanalysis datasets used in model calibration. Additionally, the ability of remote sensing data sources to consider spatial variability is a further benefit in calibrating hydrological models, which lowers the level of uncertainty in the outputs. This proposed study focuses on calibrating 3 layered Variable Infiltration Capacity (VIC) model with soil moisture, and evapotranspiration obtained from different remote sensed and reanalysis data sets in the Upper Indus basin of the Hindukush Himalayan region. As the Upper Indus basin has limited meteorological stations and no gauging stations in the Indian mainland, the current study has much scope to quantify the water resources using different remote sensing/reanalysis datasets. The results expected from this study are to find the suitable variable and reanalysis product for the calibration of the VIC model and the uncertainty associated with various remote sensing and reanalysis products.
How do simple wave models perform compared with sophisticated models and measurements in the eastern Baltic Sea?
Authors: Männikus Rain , Soomere Tarmo , Suursaar Ülo
Published: February 2023

Wave parameters set the base for the design of coastal structures. For this purpose, commonly modelled wave properties are employed. This approach is usually adequate in the open ocean conditions where variations in the wave properties are normally quite limited. The situation is different in the nearshore areas of basins of complicated shape where wave properties can be highly variable. Unfortunately, in many cases, long and sufficiently detailed wave measurements for model validation are not available. The use of default settings of wave models means that possible errors remain unknown. This approach could lead to overdimensioned structures or to structural failures. We address the magnitude of possible errors in such conditions by comparing the output of simple wave models (such as a fetch-based SMB model, the SWAN model forced with one-point homogenous wind, etc.) and a sophisticated multi-nested SWAN wave model forced with ERA-5 winds with recent wave measurements in various nearshore locations in the eastern Baltic Sea. We use records of different length over more than 10 years. While in some locations simple models or models forced with homogenous wind lead to acceptable results, in most areas more sophisticated models are needed to adequately replicate wave properties. The outcome of our analysis provides several site-specific hints for practical coastal engineering.