bluuebunny/crossref_metadata_2025 huggingface dataset:
A mathematical model for nonlinear gravity-capillary waves in a large temporal-spatial domain
Authors: Li Yan
Published: February 2023

A mathematical model of Coupled Envelope Evolution Equations (CEEEs) has been derived by Li (2022) for the propagation of nonlinear surface gravity waves. Different from the High-Order Spectral Method (HOSM) (see, e.g., Dommermuth & Yue 1987; West 1987), this newly derived model proposes to use a new pair of canonical variables introduced in the work as the main unknown parameters in the approximate Hamiltonian dynamic equations for surface gravity waves. The canonical conjugates are the envelope of the velocity potential at the free water surface and the surface displacement. They are parameters which are slowly varying in both space and time, similar to the envelope used in a nonlinear Schrödinger equation (NLSE)-based model (see, Li 2021 among others). In the limiting cases of weakly nonlinear monochromatic and irregular waves, it is shown in Li (2022) that the CEEEs can recover the analytical results of the Stokes wave theory (Fenton 1985) and the semi-analytical framework by Li & Li (2021).  Similar to the HOSM, the new model is based on a perturbation expansion and can account for the physics up to arbitrary order in wave steepness. In contrast, it has a semi-analytical feature as it is analytical for the evolution of linear waves but requires additional numerical implementations when wave nonlinearity is accounted for. The new model is especially suitable for the extremely long-term evolution of surface waves in a very large domain in space, which is more so for waves with a narrower bandwidth. In this work, the CEEEs are explored for the nonlinear evolution of gravity-capillary waves on a finite water depth. The finite water waves in the neighborhood of kh ≈ 1.363 are investigated, where k and h denote the characteristic wavenumber and constant water depth, respectively. The roles of the nonlinear forcing of mean flows due to a moderately steep wave group in extremely large wave events are examined.Key words: waves/free-surface flow, gravity-capillary waves ReferencesDommermuth, D. G & Yue, D. K. P. 1987 A high-order spectral method for the study of nonlinear gravity waves. J. Fluid Mech. 184, 267–288.Fenton, J.D. 1985 A fifth-order Stokes theory for steady waves. J. Waterway, Port, Coast. & Ocean Eng. 111 (2), 216–234.Li, Y. 2022 On coupled envelope evolution equations in the Hamiltonian theory of nonlinear surface gravity waves. submitted to J. Fluid Mech (under review).Li, Y. & Li, X. 2021 Weakly nonlinear broadband and multidirectional surface waves on an arbitrary depth: A framework, Stokes drift, and particle trajectories. Phys. Fluids 33 (7), 076609.Li, Y. 2021 Three-dimensional surface gravity waves of a broad bandwidth on deep water. J. Fluid Mech. 926, 1–43.West, B. J., Brueckner, K A, Janda, R. S., Milder, D M & Milton, R. L. 1987 A new numerical method for surface hydrodynamics. J. Geophys. Res.: Oceans 92 (C11), 11803–11824.
High-resolution AOD retrievals using MODIS data and machine learning over East Asia
Authors: Kang Eunjin , Park Seonyoung , Kim Miae , Yoo Cheolhee , Im Jungho
Published: February 2023

Atmospheric aerosols are closely related to climate phenomena such as Earth’s energy budget and the formation of clouds. Anthropogenic aerosols have rapidly increased since the industrial revolution, which is damaging to human health, leading to cardiovascular, respiratory, and allergic diseases. Consequently, comprehensive knowledge of aerosol distribution is critical, particularly at detailed spatial scales. AOD measures the vertically integrated extinction of solar radiation by atmospheric aerosol particles. Ground-based sun photometers and satellite remote sensing are mainly used to retrieve AOD as a trade-off relationship. Ground-based measurements have been considered ground truth data, and satellite remote sensing has been used to derive the spatial variability of AOD over vast areas in near real-time. The Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard the Terra and Aqua satellite is one of the main operation instruments to retrieve AOD, which has conducted atmospheric observations for almost two decades. MODIS has two well-known aerosol retrieval algorithms, Dark Target (DT) and Deep Blue (DB). Recently, the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm was developed to retrieve high-resolution AOD at a 1 km scale with better performance than DT and DB products. However, DT, DB, and MAIAC algorithms used radiative transfer models (RTM) and lookup tables (LUTs). LUTs was precalculated for a specific aerosol model using meteorological data, atmospheric gases, and constant geometry viewings, which required a high computation. The current LUT-based AOD model has reported uncertainties by aerosol model assumptions. Thus, there is room for complementing the existing AOD retrieval. Recently, machine learning (ML) has been applied with great performance for AOD retrieval. The ML-based AOD retrievals can be processed much faster and simpler without sensitive assumptions of the existing MODIS AOD algorithms. This study developed ML-based AOD retrievals that produce different resolutions of AODs (250m, 500m, and 1km) using MODIS data. The developed AODs at 250m, 500 m, and 1 km showed comparable performance, and 250 m AOD especially caught the spatial dynamics over urban areas well. When compared to MAIAC, 77.8 % of the 250 m AOD values are within the MODIS expected error (EE) envelope of ± (0.05 + 15%), followed by 500 km (76.5 % within EE), 1 km (76.3 % within EE), and MAIAC (70.08% within EE). Even ML-based AOD showed similar performance to MAIAC with three times more samples in the region where MAIAC AOD was unavailable. Our findings suggest the feasibility of ML-based estimation of high-resolution AOD using only satellite data.
Modeling influence of CH4 ebullition on carbonate system in the East Siberian Arctic Shelf
Authors: Yakushev Evgeniy , Berezina Anfisa , Novikov Matvey , Bellerby Richard. , Semiletov Igor
Published: February 2023

Progressive permafrost thawing leads to excessive transport of organic matter (OM) from the land and massive bubbling methane (CH4) release from degrading subsea permafrost in the Arctic shelf. The “extreme” aragonite under-saturation in the vast East Siberian Arctic Shelf (ESAS) reflects seawater acidity levels much higher than those projected in this region for the end of this century, as these are currently based only on atmospheric CO2.(Semiletov et al., 2016). The changes in the carbonate system can be explained by an excessive production of carbon dioxide connected due to mineralization of land origin OM or /and oxidation of methane in the areas of intensive seeping.Here, we analyze consequences of CH4 oxidation on the carbonate system state in the methane seepage areas. We used biogeochemical model BROM coupled with a vertical 2 Dimensional Benthic-Pelagic Model 2DBP and bubble fate model (Yakushev et al., 2021). BROM is a detailed biogeochemical model for the water column, benthic boundary layer (BBL), and sediments. BROM considers interconnected transformations of species (N, P, Si, C, O, S, Mn, Fe) and resolves OM in nitrogen currency. BROM includes a module describing the carbonate equilibrium; this allows BROM to be used to calculate pH and carbonates saturation states, as well as processes of formation and dissolution of carbonates. The model's alkalinity variations take into account changes connected with redox reaction consuming or releasing proton. Methanogenesis and aerobic and anaerobic methane oxidation are also parameterized. The gas bubble fate module parameterizes bubbles rising and dissolution.  An application of the model allowed to estimate connection between an intensity of CH4 release in the area (Shakhova et al., 2015) and changes in the carbonate system and to evaluate a volume of water affected. This research was funded by the Research Council of Norway: 315317 BEST-Siberian.References:Semiletov et al. (2016) Acidification of East Siberian Arctic Shelf waters through addition of freshwater and terrestrial carbon. Nat. Geosci., 9 (2016), pp. 361-365, 10.1038/NEGO2695Shakhova N et al . ( 2015) The East Siberian Arctic Shelf: towards further assessment of permafrost-related methane fluxes and role of sea ice. Phil. Trans. R. Soc. A373: 20140451.http://dx.doi.org/10.1098/rsta.2014.0451Yakushev E., Blomberg A.E.A., Eek E., Protsenko E., Totland C., Staalstrøm A., Waaru I.-K. Modeling of biogeochemical consequences of a CO2 leak in the water column with bottom anoxia. International Journal of Greenhouse Gas Control. 2021. 111: 103464.
Hydration versus dehydration reactions: increase versus decrease of solid density with pressure rise
Authors: Schmalholz Stefan Markus , Podladchikov Yury
Published: February 2023

Hydration and dehydration reactions as well as the associated fluid flow are important features of geodynamic processes. For example, hydration of rocks can significantly decrease rock strength and generate shear localization or fluids liberated by dehydration reactions in subducting rocks can flow into the mantle wedge and cause melting and magmatism. However, several aspects of (de)hydration related fluid flow and the propagation of (de)hydration reaction fronts remain unclear.Here, we study hydration and dehydration reactions with hydro-chemical numerical models based on continuum mechanics and local equilibrium thermodynamics. For simplicity, we mainly consider 1D isothermal models. We focus on the propagation velocity and direction of the (de)hydration reaction front. We define hydration as an increase of chemically, or lattice, bound water in the solid phase. Therefore, hydration requires fluid flow towards the hydration reaction front. Contrary, dehydration is a decrease of chemically bound water in the solid phase. Hence, dehydration requires fluid escape from the dehydration reaction front.Our models show that hydration requires a negative sign of the solid volume change with pressure increase across the reaction boundary, whereas dehydration requires a positive sign of solid volume change with pressure increase across the reaction boundary. The reason for this difference in sign is due to the fluid flow associated with the (de)hydration reaction which is driven by the fluid pressure gradient following Darcy’s law. Thus, for hydration to happen it must occur on the lower fluid pressure side of the reaction front compared to the side with more porous fluid. Porosity is directly related to the solid density change, so it is larger on the high solid density side of the reaction front. Therefore, the hydration reaction requires that the rock that should be hydrated is on the lower fluid pressure side of the front. Opposite can be reasoned for the dehydration front. We also include in our models the case of zero porosity, and hence zero permeability, on one side of the (de)hydration reaction front. This zero-permeability limit involves a singularity at the reaction front due to the multiplication of zero permeability with an infinite pressure gradient. We resolve this singularity in our numerical algorithm by applying a fully conservative form of the governing equations. Resolving this zero-permeability limit is in agreement with the well-established theory of non-linear degenerate parabolic equations. We apply our model to two natural settings: First, eclogite shear zones in the Bergen Arcs, Norway, where hydration of dry granulite formed eclogite. Second, olivine veins in the Erro-Tobbio unit, Ligurian Alps of Italy, where dehydration of serpentinite during subduction formed olivine.
Experimental Study of Basalt Alteration At 150 °C: An Approach To Understand Smectite Nucleation And Crystallization Pathways
Authors: Saini Vijay , Sriwastava Piyush , Mathew George
Published: February 2023

The global dominance of basaltic rock in the crust plays a dominant role in the global elemental geochemical cycle. Smectite clay is a ubiquitous alteration product of basalt. Despite having a complex silicate structure, a phyllosilicate dominance of smectite raises a question on the kinetics aspect of its formation and underlying nucleation and growth mechanism during basalt alteration. In the experimental formation of smectite, Zhang et el., 2019 have shown that coherent scattering domain size (CSDS) remains constant for starting few days during the growth of the sheet, and then stacking of fundamental particles takes place, resulting in the growth along C*. A later study by Kuliviesz et al., 2018 has shown variation in the layer charge with clay size. This implies chemical changes in the clay with its growth, which complicates the problem. The current study aims to investigate the mechanism and pathway of smectite crystallization. We have studied the role of magnesium in the growth of smectite clay and its mechanism.Experimental alteration of basaltic glass has been performed at 150 degree Celsius in two different fluid compositions. One is containing 0.3M MgCl2 and the other pure water. Products have been investigated under XRD, FTIR, TEM, and SEM; solution has been investigated under ICP AES.We found that both the experimental setup resulted globular flower-like feature along with a honeycomb structure on the glass surface. There is no XRD-detectable crystalline product, but electron microscopy has confirmed smectite, the globular flower-like structure (similar to Fiore et al. 2001). There is a discernible difference in the size of globules. Mg bearing condition has leather size flakes and globule than without Mg. Magnesium bearing experiment has shown higher Si concentration in the solution than without Mg, similar to Al's behaviour.Smectite formed in the Mg bearing experiment has twice the amount of Mg in clay structure than smectite formed in an experiment without Mg. Based on 11 oxygen, the chemical composition of smectite has been used to calculate the abundance of cation pairs in the octahedral sheet if there is a random distribution of all cations. At the same time, observation based on FTIR spectra has shown a dominance of Mg-Mg pairs. This has been observed in both experiments. Our study confirms a preferential ordering of Mg-Mg cation pairs in the octahedral sheet and better growth in the presence of Mg.Further TEM investigation is being performed to observe the fundamental particle size and chemical relation.
High-resolution simulation of CO2 dispersion in urban atmosphere of Krakow, Southern Poland
Authors: Zimnoch Miroslaw , Gałkowski Michał , Sekula Piotr , Chmura Lukasz
Published: February 2023

Effective mitigation efforts in the face of observed climate change require independent tools based on atmospheric observations to estimate greenhouse gas emissions at different spatial and temporal scales. Atmospheric transport models constitute a key element of anthropogenic emissions monitoring and verification systems. It represents atmospheric transport in such systems, which allows the use of inverse methodology to estimate emissions from observed concentrations. Reliable numerical simulations of atmospheric transport over complex urban areas require model configurations that provide adequate resolution reflecting the complex topography and land cover, as well as parameterization of physical processes optimised for the specifics of urban areas. This study presents an attempt to apply the WRF-CHEM model for the simulation of CO2 transport in the urban area of Krakow, the second largest city located in the southern part of Poland. The simulation has been performed for a 3 day period in October 2021 and was validated by a CO2 molar fraction vertical measurements performed on board of a tethered balloon operating as a commercial touristic attraction in the city centre. The modelling results have been compared with the observations to determine model performance in terms of: (i) capture the temporal dynamics of the nocturnal boundary layer formation and (ii) identifying detected CO2 plume originating from a point source to confirm the expected source position and estimate the CO2 emission from that source.The presented work was funded by the CoCO2 project, which has received funding from the European Union's Horizon 2020 research and innovation program under Grant Agreement No. 958927 and the "Excellence Initiative - Research University" program at AGH University of Science and Technology.
Cloud Droplet Number Concentration: Satellite Retrievals Improved by Advanced Atmospheric Modelling
Authors: Siméon Alexandre , Gonzalez Jessenia , Sourdeval Odran
Published: February 2023

The cloud droplet number concentration (CDNC) is one of the most important microphysical properties of liquid clouds for understanding and quantifying the effective radiative forcing by aerosol-cloud interactions (ERFaci). Indeed, CDNC is directly linked to the relevant processes of the cloud formation and evolution and is closely related to the chemical composition of the cloud condensation nuclei and the cloud droplet size distribution. Nevertheless, this key parameter still remains poorly known and is not yet operationally provided from current standard satellite retrievals. Our approach relies on an innovative determination of CDNC from satellite observations in combination with atmospheric modelling across scales, i.e., from cloud-resolving to global climate modelling. We introduce our new, community-based tool: the Satellite Simulator and Sandbox for Cloud Observation and Modelling (S3COM). Briefly, S3COM aims to simulate realistic satellite observations and cloud products from model outputs, to quantify the sensitivity of radiative quantities to cloud parameters, and to assist the development of retrieval algorithms using output fields from high-resolution models. We use realistic cloud situations (stratocumulus, cumulus, marine and continental clouds) obtained from the ICOsahedral Nonhydrostatic Large Eddy Model (ICON-LEM) to simulate top of atmosphere radiances with the Radiative Transfer for TOVS (RTTOV), from visible to infrared, observed by the Moderate Resolution Imaging Spectroradiometer (MODIS). Performance of MODIS-type algorithms coupled with ICON-LEM simulations is described and characterization of error sources is given. First results on the CDNC retrievals for warm liquid water stratocumulus clouds are presented and discussed. To go further in the improvements of the CDNC retrievals, the potentials of the multi-angle polarization and multi-viewing angle approaches using the POLarization and Directionality of the Earth's Reflectances (POLDER) observations will be investigated in a next step.
Transport and trapping of microplastics in coral reefs: a physical experimental investigation
Authors: Houseago Robert , Mendrik Freija , Hackney Christopher , Parsons Daniel
Published: February 2023

Biodiverse coastal ecosystems are vulnerable to microplastic (<5 mm) pollution due to inputs from riverine and shoreline sources which pose ecological threats and have repercussions for social ecosystem services. These ecosystems may contain an aquatic canopy covering the bed, such as seagrass meadows or coral reefs that can trap particles. Despite field measurements revealing the accumulation of plastic debris in a variety of aquatic canopies, the transport and dispositional processes that drive microplastic trapping within such canopies is barely understood. Here, we investigate for the first time the prevalence of biofilmed microplastic retention by sparse and dense branching coral canopies in a hydraulic flume under unidirectional flow. Corals were replicated through 3D-printing using a scan of a staghorn coral Acropora genus, a branching coral that encompasses one-fifth of extant reef-building corals, globally.Trapping mechanisms by coral canopies were identified, and include: a) interception of particles with the coral acting as a barrier and microplastics and settling to the bed; b) settling of microplastics on the branches or within the structure of the coral and c) accumulation in the downstream region of individual corals. Trapping efficiency was found to depend on bulk velocity and canopy density, with up to 99% of microplastics retained across the duration of the experiments. Surprisingly, sparse reefs may be as vulnerable to microplastic trapping and contamination as denser canopies under certain flow velocities, with the latter found to retain only up to 18% more microplastics than in sparser conditions. Flow velocity profiles provide insights into the relationships between canopy hydrodynamics and microplastic trapping and distribution. The results indicate coral reefs may form areas of accumulation for microplastic pollution through their observed high trapping efficiency that may otherwise have been transported greater distances.
Wavelet-based post-processing of NWP precipitation forecasts
Authors: Johnson Fiona , Jiang Ze
Published: February 2023

Reliable flood forecasts are dependent on accurate quantitative precipitation forecasts. Despite improvements in the resolution and schematisation of Numerical Weather Prediction (NWP) models, there are still substantial biases in their precipitation forecasts. Biases are present at a range of time scales and correctly representing the multi-temporal scale properties of precipitation including its persistence and variability is vital. In this presentation a new method for post-processing NWP model precipitation forecasts is developed. The new method is based on continuous wavelet transforms (CWT) which correct the statistical characteristics of the precipitation forecasts across a range of time scales. The precipitation amounts are corrected using a simple quantile mapping of the amplitude of each time scale of the wavelet decomposition. To account for uncertainty in precipitation timing, we also adjust the phase of the CWT randomly to create an ensemble of post-processed forecasts. Spatial correlations are preserved by maintaining the same phase adjustments at each different precipitation forecast location.  The new method is demonstrated using hourly forecast data from the ACCESS model over the period March 2018 to September 2021  for a network of 158 gauges around Sydney, in eastern Australia. The new method improves the correlation of the forecasts and reduces the root mean square error. The spatial correlation structure of the post-processed forecasts is also improved. Correctly representing spatial patterns of precipitation is vital to ensure that catchment averaged precipitation and the resulting flood forecasts are correct.
Ocean alkalinity enhancement through enhanced silicate weathering in coastal areas: a long-term mesocosm study
Authors: Hylén Astrid , Kreuzburg Matthias , De Wolf Saïd , Burdorf Laurine , Fiers Géraldine , Goossens Cedric , Van Heurck Benjamin , Theetaert Hannelore , Verbrugge Silke , Cnudde Veerle , Cattrijsse André , Meysman Filip
Published: February 2023

Enhanced silicate weathering (ESW) in coastal environments is a promising method for ocean alkalinity enhancement. The idea behind ESW is to generate alkalinity by application of silicate minerals in coastal areas, where waves, currents and bioturbation can speed up the weathering rate. Due to its potentially large CO2 sequestration capacity and relatively high technological readiness, allowing rapid upscaling, coastal ESW currently receives substantial interest from researchers and policymakers. However, the vast majority of studies on ESW have been conducted in idealised laboratory conditions, while research on the method in natural environments is lacking. As a result, the CO2 sequestration efficiency and environmental risks when applying ESW in the field remain largely unknown.Here we present results from the first and longest-running mesocosm experiment investigating ESW and associated CO2 uptake in coastal marine sediments. Using tanks containing one square meter of natural seafloor each, we have studied biogeochemical cycling in sediment treated with the fast-weathering silicate mineral olivine. Lugworms (Arenicola marina) were added to some tanks to investigate the effect of bioturbation on the olivine dissolution rate, as well as the impact of olivine addition on biota. In the mesocosms, we quantified the sedimentary release of alkalinity and other weathering end-products (trace metals and dissolved silicate). Five years into the experiment, olivine dissolution is obvious from an elevated sedimentary alkalinity release and decreased average olivine grain size. The elevated alkalinity release has further led to higher CO2 sequestrations in tanks with olivine. Based on the results from this unique mesocosm setup, we will discuss the large-scale effect of ESW on biogeochemical cycling in coastal ecosystems.
Improved prediction of soil organic carbon sequestration potentials in Austrian arable soils as simulated by multi-model ensembles
Authors: Bernardini Luca Giuliano , Rosinger Christoph , Keiblinger Katharina , Bodner Gernot
Published: February 2023

Soil organic carbon (SOC) constitutes the largest terrestrial biological carbon pool globally. SOC in croplands has declined by approximately 50% since the intensification of agriculture. In light of climate change due to rising greenhouse gas concentrations in the atmosphere, the 4p1000 initiative was launched, suggesting that anthropogenic CO2 emissions could be offset by increasing SOC stocks in arable land by 0.4% per year by implementing more sustainable agronomic measures. In order to estimate the potential effect of different measures on SOC at the national scale, modelling approaches are required. In the last decades, a wide array of SOC models have been developed and validated for different soils, climate conditions and land uses across the globe. These models all have their own advantages, disadvantages, and sources of uncertainty. Carbon inputs into soil, a major driver of SOC dynamics, are an estimated quantity in all modelling procedures and represent an additional, large source of uncertainty. To reduce uncertainties, multi-model ensembles are suggested to outperform single model runs. The objective of this study is to determine the optimal SOC model ensemble to reduce estimation errors in future studies.Therefore, a combination of four carbon turnover models (RothC, Yasso07, ICBM, and C-TOOL) and five published carbon input estimation methods was evaluated by comparing simulations to experimental data from six long-term experiments with 56 treatments on arable land in Austria, with durations from 10 to 32 years to obtain a possible optimal combination for future SOC modelling studies in Austria. Evaluation of model prediction was performed by calculating the absolute mean error (AME), Root Square Mean Error (RMSE) and coefficient of determination on yearly SOC changes to eliminate the effect of different experimental durations on model evaluation.We show that obtained models strongly differ in their stock estimates, and our selected ensemble strongly improved the estimations of SOC against single model runs with significantly lower absolute mean errors and root mean square error. This is in accordance with literature results and presents a way forward towards a more accurate modelling. We thus argue that multi-model ensembles to estimate SOC stocks in arable soils in Austria should be preferred over single-model approaches due to improved accuracy.
Response of storm surge spatiotemporal feature to climate patterns change on coast of China in past hundred years.
Authors: Zhang Yue
Published: February 2023

  To investigates multidecadal and long-term variations of storm surge spatiotemporal feature, we use reconstructed daily maximum storm surge levels on the coastal area of China in the past hundred years. By considering both surge height and each storm surge duration, we proposed a comprehensive impact of storm surge, called” Accumulated Storm Surge Potential Impact (ASPI)”. The results show that even the frequency and duration of storm surges have not changed significantly under global warming, the comprehensive impact has increased rapidly and normal storm surge have become stronger since mid-1990s. The spatial distribution of storm surge impact has “-++” zonal tripole pattern or”-+” zonal dipole pattern in different time scale. In addition, El Niño-Southern Oscillation (ENSO)events have a certain effect on the frequency, duration, and intensity of storm surge activity, which identified as one of the key climate patterns influencing storm surges. The impact of the Pacific Decadal Oscillation (PDO) on the frequency, duration, and intensity of storm surge activity at different phases are also different, with clear regional distribution features for each phase. This study highlights the potential influence of eastern China storm surge loadings on the western North Pacific (WNP) climate patterns, thus improving our understanding of storm surge climate variability over the WNP.
The Taverna San Felice dike: insights into magmatic intrusion processes in carbonates and relationships with the Middle-Late Pleistocene volcano-tectonic activity of the Garigliano graben and Roccamonfina volcano (southern Italy)
Authors: Natale Jacopo , Vitale Stefano , Giordano Guido , Fedele Lorenzo , Lucci Federico , Vona Alessandro , Isaia Roberto , Ciarcia Sabatino
Published: February 2023

The Roccamonfina volcano, active through the Middle-Late Pleistocene, is located within the Garigliano graben in southern Italy. It produced several effusive/mild explosive monogenetic events interspersed by ignimbrite eruptions. Several volcano phases have been characterized by fissure eruptions along the volcano slope, summit caldera, and graben-bounding carbonate reliefs. In this work, we present a multidisciplinary study of one of the most impressive examples of a magmatic dike intruded within the Cretaceous carbonates and Lower Pleistocene breccia of Mt Cesima, northeast of the Roccamonfina volcano. We have reconstructed the geometric features of the main dike, the stratigraphy of the erupted products and the underlying tephra from the Roccamonfina volcano. Results indicate that a ~1 km long fissure opened up at the surface, emplacing three pyroclastic units and building up a welded rampart system. Geochemical and petrological data show that a tephritic magma fed the eruption, with indications of an open-system mafic recharge before the eruption, without contribution from carbonate host-rock assimilation. Although the composition resembles that of the first (old) stage of Roccamonfina, stratigraphic data suggests that this eruption is younger than the White Trachytic Tuff (WTT, 230 ka) eruption and likely has a source reservoir distinct from the volcano. Structural data indicate that the dike is broadly oriented E-W, partially deflected along a pre-existent NE-SW fault damage zone and intruded during an important N-S rifting event in the Middle-Upper Pleistocene. Extensional tectonics subsequently produced the exhumation of the dike and the erosion of the pyroclastic material, only preserved in structural lows. This work shows that important extensional tectonic pulses may intertwine with the eruptive history of a volcano, with dike intrusions representing the hint of such events.
Ab initio-assisted computational thermodynamics: a modern approach to phase diagram calculation at planetary conditions
Authors: Belmonte Donato , La Fortezza Mattia , Menescardi Francesca
Published: February 2023

Despite the outstanding progress in computer technology and experimental facilities, understanding melting processes and solid-melt phase equilibria at planetary conditions is still an open challenge. In this work a modern computational approach to predict melting phase relations at HP-HT by a combination of first principles DFT and MD calculations, polymer chemistry and equilibrium thermodynamics is presented and discussed. The adopted theoretical framework is physically-consistent and allows to compute multi-component phase diagrams relevant to planetary interiors in a broad range of P-T conditions by a convex-hull algorithm based on the simplex method for Gibbs free energy minimisation. The calculated phase diagrams are in turn used as a source of information to gain new insights on both present-day and early Earth melting processes. Some examples of application of the above method to the CaO-MgO-Al2O3-SiO2 system (CMAS) and relevant ternary and binary subsystems highlights as pressure effects are not only able to change the nature of melting of some minerals (like olivine and pyroxene) from eutectic to peritectic (and vice versa), but also simplify melting relations by drastically reducing the number of phases with a primary phase field at HP-HT conditions. Since the volume-pressure integral contribution to Gibbs free energy become relevant at planetary interior conditions, special attention must be paid to the choice of the P-V-T EoS formalism in order to avoid physical unsoundness or spurious effects in thermodynamic properties (e.g. negative thermal expansion). Ab initio-assisted computational thermodynamics is thus outlined as the main route towards the future development of physically-consistent (besides internally-consistent) thermodynamic databases for global-scale planetary investigations.Financial support by the Italian Ministry of University and Research (MIUR PRIN 2017, Project 2017KY5ZX8 and MIUR PRIN 2020, Project 202037YPCZ) is warmly acknowledged.   
CAMELS-SAX: A meteorological and hydrological dataset for spatially distributed modeling of catchments in Saxony
Authors: Hauffe Corina , Brandes Clara , Lei Kan , Pahner Sofie , Körner Philipp , Kronenberg Rico , Schuetze Niels
Published: February 2023

Comparative hydrology has been found to deepen our understanding of hydrological processes in catchments and helps to improve the proper evaluation of hydrological models. Recently, the global hydrological community has developed a series of publicly available, large-scale  „CAMELS“-datasets that provide catchment attributes and meteorological time series of catchments on a national level. These datasets include catchment-averaged values of catchment characteristics and meteorological time series and therefore allow only lumped modeling. In this study, we introduce a new dataset "CAMELS-SAX" for large-sample studies in the region of Saxony (Germany), which has a high diversity and heterogeneity of catchment attributes, such as geology and land use. "CAMELS-SAX" consists of meteorological and hydrological time series covering 60 years of data on a daily timestep for more than 200 catchments. The dataset includes spatially distributed catchment attributes and covers an area of about 23.000 km² with undisturbed and anthropogenic-influenced catchments ranging from 1 km² up to 5.000 km², which can be used for spatially distributed modelling. We will provide the standardized dataset for the German Federal State of Saxony for studies evaluating distributed models' performance on a smaller spatial scale. In the presentation, we show an overview of catchment attributes, time series, and hydrological signatures for the subset of undisturbed catchments. In addition, we present the results of a sensitivity analysis of the hydrological behavior caused by climate change.
Laboratory evidence of modifications to the Benjamin-Feir instability by shear flow
Authors: Rømcke Olav , Smeltzer Ben , Lenain Luc , Pizzo Nick , Ådnøy Ellingsen Simen
Published: February 2023

Modulational or Benjamin-Feir instability (BFI) causes trains of Stokes waves to form groups through energy transfer to specific side-bands in the frequency spectrum. The groupiness developing as the wave propagates is believed to be a candidate mechanism for the formation of extreme rogue waves. 

Theoretical [1,2] and experimental [3] studies have shown that the presence of a vertically sheared current can either stabilise or destabilise the wave train depending on the sign of the associated vorticity. A recent theory from a Lagrangian reference system shows that, if an Eulerian current is present which is equal and opposite to the Stokes drift velocity profile, the BFI can vanish altogether [4]. 

We conduct an experimental study of the groupiness and sideband growth of regular waves travelling on velocity profiles of different shear. The experiments are conducted in the recirculating, open water channel at NTNU where an active grid at the inlet allows us to tailor the velocity profile to nearly cancel the Stokes drift profile. We demonstrate how the groupiness is drastically reduced in this case. The sideband growth and, for steep waves, the distance travelled before breaking occurs is investigated for different velocity profiles and steepnesses while keeping the wavelength constant. 

[1] Baumstein A 1998 “Modulation of gravity waves with shear in water” Stud. Appl. Math. 100 365-390.
[2] Thomas R., Kharif C and Manna M 2012 “A nonlinear Schrödinger equation for water waves on finite depth with constant vorticity” Phys. Fluids 24 127102.
[3] Steer JN, Borthwich AG, Stagonas D, Buldakov E and van den Bremer, T 2020 “Experimental study of dispersion and modulational instability of surface gravity waves on constant vorticity currents” J. Fluid Mech. 884 A40.
[4] Pizzo N, Lenain L, Rømcke O, Ellingsen SÅ, Smeltzer BK 2023 "The role of Lagrangian drift in the geometry, kinematics and dynamics of surface waves"  J. Fluid Mech. 954 R4.
ENSO diversity, transitions and projected changes 
Authors: Freund Mandy , Brown Josephine , Marshall Andrew , Tozer Carly , Henley Benjamin , Risbey James , Sharmila Sur
Published: February 2023

Diverse characteristics of ENSO events occurring either in the Eastern Pacific (EP) and Central Pacific (CP), have led to a shift in the traditional view of tropical coupled ocean- atmosphere systems and present a challenge in light of recent changes and possible future ENSO behaviour. The probability of a transition from one type of event to another is influenced by multiple factors of which many are projected to change with global warming. Here we assess the likelihood of transition from one ENSO state to another in long instrumental records and climate models. We find specific transitions are more likely than others. For example, strong EP El Niño events are more likely to transition to La Niña events than to El Niño events. The strength of an El Niño event is found to be an important factor. Consecutive CP El Niño events, unlike consecutive EP El Niño events, are more likely to occur after a strong CP event. Under a high emission scenario, we find significant changes of transitions.
Modelling and reforecasting real-time reservoir operation and outflow with neural networks: case study of the multi-purpose Sirikit reservoir in Thailand
Authors: Wannasin Chanoknun , Brauer Claudia , Uijlenhoet Remko , Weerts Albrecht
Published: February 2023

Real-time reservoir operations are highly dependent on decisions made by reservoir operators, which are difficult to simulate accurately with process-based hydrological models. Data-driven models, particularly those based on machine learning (ML), have been shown to be able to overcome the limitations typically encountered in process-based models. Despite a large number of ML studies in reservoir operation modelling, only few studies have focused on ML model performance in real-time reservoir operation and outflow forecasting. This study aims to investigate the capabilities of the Recurrent Neural Network (RNN), Long Short-Term Memory (LSTM) and Gated Recurring Unit (GRU) in simulating and reforecasting real-time (daily) reservoir operation and outflow, considering uncertainties in input data, training-testing periods and different algorithms. A major, multi-purpose reservoir, namely the Sirikit reservoir, in the upper Chao Phraya River basin Thailand was used as the case study. The main inputs for the ML operation models included the daily reservoir outflow, inflow, storage and the month of the year. We applied the distributed wflow_sbm model for inflow simulation (using MSWEP precipitation data) and inflow reforecasting (using ECMWF precipitation data). Daily reservoir storage was obtained from observations and real-time recalculation based on the reservoir water balance. The ML operation models were trained and tested with 10-fold cross-validation. Results show that RNN, LSTM and GRU can reconstruct real-time reservoir operation and provide accurate outflow when training data cover both regular and extreme conditions. For multi-day reforecasting, the model performances are appropriate for the current day up to 2-day lead times for low outflows and up to 6-7 days for high outflows. GRU is potentially the most accurate, robust and convenient model to be used in practice. We conclude that with some further improvements, the ML operation models can be effective and applicable tools to support decision-making for real-time operational water management.
Fracturing of rocks in Bavarian geothermal reservoirs – Experimental and numerical investigation of borehole stability
Authors: Mattheis Justin , Drexl Catharina , Herrmann Leon , Yildirim Ridvan , Thuro Kurosch
Published: February 2023

As one of the most promising settings for deep geothermal energy, the North Alpine Foreland Basin in Bavaria (SE Germany) is currently a location of ongoing planning, development, and operation of hydrothermal energy projects. The high risks associated with the more than 3000 m deep wells, drilled into the reservoir still limits an accelerated exploration and usage of the reservoir’s potential. The heterogeneities of rock mass and thus uncertain subsurface conditions threaten the wellbore integrity and lower the predictability of hydraulic reservoir stimulation and its success. Characterizing the fracturing properties of in situ samples and analogue rocks, extracted from nearby quarries, aims to increase certainty in expected fracturing processes.  

To determine the fracture toughness and fracture energy in tensile (mode I) and shear mode (mode II) two experimental setups are used. With the double edge-notched Brazilian disk (DNBD) test the mode II fracture toughness is measured by inducing shear failure through uniaxial compression of a bi-notched Brazilian disk. The semi-circular bend (SCB) test applies tensile forces on a notched semi-cylindrical disk by bending the sample around three roller supports and produces mode II fracture. A high-speed camera records the test procedure for further characterizing the fracture propagation and the influence of inhomogeneities.

Together with elastic and strength properties of the analog rocks, extracted from further rock mechanical tests, the fracture energy values serve as input for a numerical study of borehole stability. By using the hybrid FEM-DEM method, complex 2D and 3D borehole models are computed without losing the relation to realistic processes. In multiple scenarios, that are representative of the geothermal projects in the North Alpine Foreland Basin, the rock mass behavior during borehole excavation is simulated with the Irazu software. Additionally, pre-existing fracture networks, in situ stresses and pore-fluid pressure are integrated, which influence the resulting fracture pattern and fracturing degree. The coupled mechanical-hydraulical model will later be extended to additionally incorporate thermal effects.

When considered during future drill operations these results can help to lower the economic risk that is still associated with deep geothermal operation and consequently increase the development speed to a sustainable heat energy provision in SE Germany.

This work is part of the Geothermal-Alliance Bavaria and funded by the Bavarian State Ministry of Science and Arts (StMWK).

 

Keywords: numerical FDEM simulation; laboratory testing; fracture energy; geothermal wellbores; North Alpine Foreland Basin, SE Germany
Basin Evolution Controls on Grain Size Fining: Beyond the 1D Solution
Authors: Wild Amanda , Braun Jean , Whittaker Alex , Castelltort Sébastien , Fillon Charlotte
Published: February 2023

Interpretation of the sedimentary record requires a thorough understanding of both external forcing and autogenic dynamics within sedimentary basins. This research analyzes the influence of autogenic and basin dynamics on grain size fining through landscape evolution modeling (Myr timescales) of a flexural foreland basin and observations from real-world basins with well-known underlying subsidence for comparison. In previous work, we have incorporated the Fedele and Paola (2007) self-similar gravel grain size method in two dimensions allowing for the formation of multichannels (2D) into the FastScape (Braun and Willett, 2013) landscape evolution model. We have validated this modelling approach against the self-similar grain size results of Duller et al. (2010) without multiple channels (1D). Here, we analyze different upstream precipitation and flexural elastic thicknesses (impacting the pattern and rate of subsidence) on the evolution of grain size fining, stratigraphic thickness, topography, and channel dynamics. We use real world scenarios with known underlying subsidence, grain size fining, and surface ages (such as the Grapevine Mountain fans of Death Valley) to compare with model results. Underlying subsidence controls on grain size have been well described by Duller et al. (2010), but never with the consideration of channel and topographic dynamics that vary the deposition rate relative to the subsidence rate across the basin. Braun (2022) has described the upstream area and precipitation influence relative to downstream on fan extents, but has not yet applied this to grain size fining trends. Our results show that multiple channels influence the grain size fining solution (more fining) compared to solutions with a single set channel pathway in conditions ranging from full sediment capture in the basin to full bypass, and these results vary depending on fan extents and the pattern of underlying subsidence. The model can be also used to estimate a variance range in grain size fining in which autogenic dynamics may be playing a greater role to statistically rule out or acknowledge a potential autogenic control induced by channel dynamics. Braun & Willet (2013). Geomorphology: 180. Braun (2022). ESP: 10(2). Duller et al. (2010). JGR: ES 115(F3). Fedele & Paola (2007). JGR: ES 112(F2).