bluuebunny/crossref_metadata_2025 huggingface dataset:
A generic approach to parameterize the scaling properties of atmospheric delays in InSAR time-series
Authors: Mulder Gert , van Leijen Freek , Hanssen Ramon
Published: February 2023

The observed phase in time-series of Interferometric Synthetic Aperture Radar (InSAR) products is a combination of primarily differential topography, line-of-sight displacement and atmospheric delay contributions. These components need to be disentangled to derive accurate atmospherical products from InSAR. However, isolating the atmospheric component from InSAR has been proven difficult as it is spatiotemporally highly dynamic and a superposition of two atmospheric states.Here we propose an approach to parameterize the stochastic properties of the single-epoch atmospheric delay field as a way to represent the atmospheric signal in InSAR.We found that the atmospheric signal of a time-series of interferograms can be characterized by structure functions, which can be used to isolate the single-epoch structure functions. Using two isotropic and three anisotropic scaling parameters it is then possible to construct a structure function characterizing the atmospheric signal per SAR acquisition. Especially, the isotropic parameters for the small scale and large scale atmospheric delay variations, can be used to characterize the atmospheric signal. For a test set of 150 Sentinel-1 acquisitions, this results in a difference in signal strength of the InSAR atmospheric signal with a factor of about 10 for small scale and 50 for large scale variations.Our parametrization demonstrates that the scaling properties of the InSAR atmospheric signal for different SAR acquisitions are very similar and can be described using only five parameters. After parameter estimation we can then provide time-series of the expected atmospheric signal using distance and direction only for any combination of points within the InSAR image. 
Experimental Measurements of Electric and Magnetic Fields in Simulated Martian Dust Storms
Authors: Reid David , Aplin Karen
Published: February 2023

Despite no direct observations of lightning on Mars, it is expected to occur. The planet is known to have large dust storms - which are believed to generate electric and magnetic fields. Magnetic fields are also expected in dust storms on Earth, though measurements are extremely limited. Understanding of electric and magnetic fields of this prevalent feature of the Martian landscape is vital to understanding and developing missions of Mars.Two hypotheses were postulated. Firstly, the vertical separation of charge is responsible for the electric field, and, secondly, that the spiralling motion of the charged particles is responsible for the magnetic field. An experimental apparatus was designed to isolate the vertical and horizontal components of the motion in a dust storm in the lab with Martian analogue material by dropping or rotating the particulates respectively. In this rig electric fields are measured using a field mill (CS110) and magnetic fields with a search coil magnetometer (LEMI 133, the engineering model from the postponed ExoMars22 mission). The rig is carefully screened from background electrical and magnetic fields.The equipment is currently being commissioned, and in the vertical separation mode, particulates such as polystyrene and glass beads were dropped onto a Faraday cup. By determination of the capacitance of the tank, the voltage signal can be converted into charge. In addition to this, the signals from the Faraday cup and field mill can be visualised across the time profile of a given drop. In the horizontal motion mode, the particulate is mixed with a paddle, akin to an ice-cream machine, to entrain the dust in a vortex. Results from these lab-based experiments are presented here.
Deep learning based coordinates transformations for improving process understanding in hydrological modeling system
Authors: Hu Xinqi , Tuo Ye , Disse Markus
Published: February 2023

Improving the understanding of processes is vital to hydrological modeling. One key challenge is how to extract interpretable information that can describe the complex hydrological system from the growing number of observation data to advance our understanding of processes and modeling. To address the problem, we propose a data-driven framework to discover coordinate transformation, which transfers original observations to a reduced-dimension system. The framework combines deep learning method with sparse regression to approximate the specific hydrological process: deep learning methods have a rich representation to promote generalization, and sparse regression can sparsely identify parsimonious models to promote interpretability. By doing so, we can identify the essential latent variables under a physically meaning-wise coordinate system where the hydrological processes are linearly and sparsity represented to capture the behavior of the system from observations. To demonstrate the framework, we focus on the evaporation process. The relationships between potential evaporation and climate variables including long/short wave radiation, air temperature, air pressure, relative humidity, and wind speed are quantified. The connection between the climate variables and coordinates components extracted are evaluated to capture the pattern of climate variables in the component space. The robustness and statistical stability of the framework is examined based on distributed observations from FluxNet towers over North America. The resulting modeling framework shows the potential of deep learning methods for improving our knowledge of the hydrological system.
Understanding plastic waste dynamics, correlations with hydrological extremes and its contributions to the development of innovative interception and mitigation solutions within Kingston Harbour, Jamaica
Authors: Correia Renata , Assumpção Thaine , Buchanan Luke , Fletcher Darren , Maxam Ava
Published: February 2023

Mismanaged plastic waste continually accumulates in the marine environment. A large amount of its emission to the ocean originates on land and is transported by rivers, streams and artificial drains. However, monitoring efforts and knowledge building on the dynamics and quantification of these emissions based on field research is scarce and subject to local catchment scale.Here, we present an experimental study of plastic waste transport and retention dynamics in artificial drains (gullies) subject to flash floodings in short drainage areas of Kingston, Jamaica. We developed a novel plastic waste piles survey using UAV and field measurements. The offered investigation has the potential for estimation of plastic waste piles (i) volumes and composition, (ii) transport-retention-remobilization cycles and (iii) correlation with local hydro-meteorology, especially during peak events, where most of the plastic waste is transported.Until now, monitoring efforts were carried out on the lower stretch (1km) of three gullies flowing to Kingston Harbour and the Caribbean Sea during 90 days in the hurricane season of 2021 on a bi-weekly basis. The current dataset includes 24 orthorectified images of the gullies and plastic waste piles. Direct samples of the plastic waste piles are being collected for ground-truth validation. We observe that plastic waste piles are more prominent when large objects (such as refrigerators, tree branches or tyres) are present, forming a base for greater accumulation and affecting remobilization cycles.These results are essential for understanding macroplastic transport processes and the development of innovative technological solutions preventing plastics inflow into the ocean. It has the potential to provide insights into the operational performance before and after the implementation of interception solutions or mitigation measures. Furthermore, it serves as baseline data to strengthen local policy-making on initiatives assessing harmful effects in surrounding ecosystems.
Growth of normal faults in flexural foreland basins: a case study of the Northern Alpine Foreland Basin
Authors: Eskens Lucas , Andrić Tomašević Nevena , Müller Matthias , Herrman Rolf
Published: February 2023

The nucleation and subsequent vertical and lateral growth of normal faults have been the focus of many studies in extensional settings as these are important conduits for heat or fluid transfer. However, little attention has been attributed to normal fault growth in flexural foreland basins. The flexural downbending of the foreland plate generates extensional stresses, leading to the formation of normal faults in flexural foreland basins. Therefore, besides having an important role for subsurface fluid flow, normal faults in foreland basins are a fingerprint of the tectonic events associated with the downbending of the lower plate during collisional tectonics. In this study, we quantify the Oligocene to Early Miocene spatial and temporal evolution of the normal faults and their growth styles in the Northern Alpine Foreland Basin (NAFB). For this approach we use two 3D seismic volumes in the depth domain, located in the German part of the NAFB, to interpret both normal faults and prominent seismic horizons. This allows us to construct throw-depth and throw-length profiles to quantify changes in fault-parallel and down-dip throw patterns. This analysis allows us to reconstruct how the normal faults in our study area grew in 3D over time. Throw-depth profiles of the faults generally record throw maxima for either the foreland unconformity reflector or Oligocene aged reflectors, subsequently decreasing both up-and downward. This implies that following nucleation, the faults grew both upward into the syn-flexural fill of the basin and downward into the pre-flexural basement. Furthermore, comparing throw-depth and throw-length profiles of the faults in both seismic volumes shows that lateral fault growth is coupled with the fault tip moving towards younger stratigraphy. This is highlighted in the eastern German NAFB, where the vertical linkage between a lower segment that nucleated in the Eocene-Rupelian and an upper segment that nucleated in the Late Chattian is observed. To summarize, the observations imply that normal faults in the German NAFB were newly formed during flexural downbending of the European plate, preferably nucleating at the top of the plate before growing downward. This is different from fault growth observed in purely extensional settings, where faults typically grow upward instead of downward. Finally, the variable normal fault activity in the different seismic volumes in the German NAFB point out basin-parallel variations in flexural subsidence, possibly driven by spatiotemporal variations in Alpine frontal thrusting and/or slab pull.
Estimating future permafrost carbon-climate feedbacks using a coupled Earth System Model
Authors: Gaillard Rémi , Guenet Bertrand , Peylin Philippe , Cadule Patricia , Chéruy Frédérique , Ghattas Josefine , Vuichard Nicolas
Published: February 2023

Permafrost soils located in high latitudes contain about 1500 petagrams of carbon. The strong and rapid warming of the Arctic climate threatens this important carbon stock. Permafrost thaw exposes previously frozen organic matter to decomposition by microorganisms, resulting in CO2 and CH4 emissions into the atmosphere that contribute to strengthening the initial warming. On the other hand, rising atmospheric CO2 concentration increases vegetation primary productivity in a feedback known as fertilization effect. In addition, the melting of permafrost may also likely provide more nitrogen in the soil that could stimulate plant growth. The balance between these competing processes is thought to be the primary driver of future permafrost carbon stocks. However, both the amplitude and timing of future net carbon emissions of permafrost areas remain highly uncertain. Reducing the uncertainty on net carbon balance in high latitudes would help improve the accuracy of carbon budget, and thus would impact political and social decisions towards the net zero target.Up to then, the impact of different future climate scenarios (RCP, SSP or similar) on permafrost have been largely explored with offline Land Surface Model simulations but feedbacks with the atmosphere and ocean cannot be represented in such configurations. Using the IPSL Earth System Model that couples the atmosphere, the ocean and continental surfaces (i.e., ORCHIDEE model), the future evolution of climate-carbon feedbacks in permafrost regions is assessed. In particular, the feedback between climate change and the carbon cycle and the fertilization effect are analyzed with the C4MIP formalism (γ and β parameters). A particular focus is put on the role of the nitrogen cycle through its interactions with the carbon cycle. In addition, the impact of soil insulation by soil organic carbon and surface mosses on thermal transfers is also analyzed in the context of coupled land - atmosphere simulations. The importance of surface insulation i) to maintain realistic surface air temperature, especially during spring time, avoiding large surface - atmosphere feedbacks with unrealistic cooling in the arctic and ii) to sustain large permafrost extent (close to observations) is highlighted.
How good can we get? – An analysis of systematic errors in common models for all-sky imager based irradiance nowcasting for solar energy
Authors: Gregor Philipp , Zinner Tobias , Mayer Bernhard
Published: February 2023

Solar energy from photovoltaics (PV) is a major contributor to the power production, e.g., in Germany, with a growing share. It is a major contributor to renewable power production but highly volatile as it is heavily influenced by atmospheric conditions. Especially shading by clouds can change within seconds to minutes and cause ramps in irradiance and solar power production. Accurate short-term predictions (nowcasts) of irradiance for the next minutes can help to alleviate the impact of this volatility and improve the integration of solar power into energy grids. One approach for nowcasting is the use of all-sky imagers (ASI), ground based fisheye cameras which capture the current cloud situation. Therefore, cloud information is extracted from current images, future cloud states are extrapolated and converted into an irradiance nowcast. Despite substantial progress in the quality of the applied methods, current ASI nowcasting models still exhibit significant nowcast errors and struggle to reliably outperform persistence nowcasts for all situations. Therefore, we assessed the implications for nowcast performance of two common fundamental simplifications of ASI nowcasting models. Firstly, cloud evolution is often modelled by advection, i.e. simple displacement over time. Growth, shrinking or reshaping of clouds is usually neglected in the models. Additionally, the ASI viewing geometry may introduce a misrepresentation of the depicted cloud scene, which is also commonly neglected. The ASI views surrounding clouds from a single ground position and under varying angles. For direct irradiance however, the horizontal distribution of clouds and their intersection in the direction of the sun is essential. While ASI images are usually reprojected to comply with the required horizontal representation, the original difference in actual and required viewing geometry cannot be fully compensated. E.g., breaks between distant clouds may not be clearly visible by the ASI although modulating the irradiance. Kurtz et al. (2017) demonstrated a major impact by this geometric limitation. We applied a nowcasting model to synthetic ASI images of a simulated cloud scene to extend this previous study and analyze the errors introduced by both of the two commonly used simplifications of ASI nowcasting models. A large fraction of the nowcasting error is attributable to the simplifications, which implies a systematic baseline error of common ASI nowcasting models. While the implementation of more evolved cloud evolution and a better representation of relevant cloud geometry are challenging, this work indicates, that efforts to implement these improvements in ASI nowcasting models are a chance for a leap in performance of future nowcasting models. Kurtz, B., Mejia, F., and Kleissl, J.: A virtual sky imager testbed for solar energy forecasting, Solar Energy, 158, 753–759, https://doi.org/10.1016/j.solener.2017.10.036, 2017.
Lithosphere-asthenosphere structure and impact on serpentinization processes and topography across the plate boundary between Iberia and Europe
Authors: pajang sepideh , Mouthereau Frederic , Robert Alexandra , Callot Jean-Paul
Published: February 2023

The tectonic evolution of the plate boundary between Iberia and Europe since the Variscan and more clearly since the Mesozoic rifting is at the origin of heterogeneities of densities and structure, in the crust and the mantle, which have an impact on the distribution of the current stresses and post-orogenic uplift in the Pyrenees. Here, we investigate the lithosphere structure across the Pyrenees and Western Europe using LitMod2D that integrates geophysical and petrological data sets to produce the thermal, density, and seismic velocity structure of the lithosphere and upper mantle. Of particular interest is the chemical composition of the mantle, including the degree of serpentinization near the North Pyrenean Fault (>10 km), and the shape of the lithosphere-asthenosphere boundary at a larger scale (>100 km). The topography and geophysical constraints, including LAB geometry, Vs, Vp data are well reproduced for a weak fertile Phanerozoic lithosphere. Our results suggest that accounting for serpentinization allows fitting second-order gravity and seismological features in the lithosphere, but not topography which is controlled to first-order by high lateral variability in crustal thickness and lithosphere strength.
Automatization of an early cereal maps classification model from 2010/2011 to 2021/2022 in a semi-arid region
Authors: Khlif Manel , Escorihuela Maria José , Chahbi Bellakanji Aicha , Paolini Giovanni , Kassouk Zeineb , Lili Chabaane Zohra
Published: February 2023

Cereals represent an essential factor in the economy and food security, especially for countries that are not self-sufficient and depend on imports like Tunisia. Obtaining an early cereal map without the need to collect field data and without waiting for the end of the agriculture season helps the government to make early decisions. Hence, the first objective of our study is the development of an automatic classification model first calibrated for one agricultural year, 2020/2021 (2021), and then validated over the years 2011 through 2022 in the Kairouan governorate. The second objective is the development of a forecasting model in order to have early cereal maps several months before the harvest which occurs in June. Using Sentinel 2 and Landsat 5-7-8 data, different vegetation indices percentiles have been calculated. In order to select the best indices for cereal classification, a feature importance study over all the indexes was performed using the random forest classification algorithm reference year classification. A land cover classification model was validated for the reference year 2021, with an overall accuracy of 89.3%. This classifier has been used to elaborate land cover classification maps since 2011, focusing mainly on cereal crops. Using Sentinel 2 data, a good precision (P) for cereal crops was found, between 85,8% and 95,1%. Good to moderate accuracies were obtained when using Landsat data, between 41% and 91,8%. Then, a land cover forecasting model was validated for 11 years for different forecasting periods where we found excellent results four months before harvest (in February). We were able to obtain the cereal crop maps with a P between 85,1% and 95,1% using Sentinel 2 data and between 42,6% and 95,4% using Landsat data from four months before harvest. However, confusion between cereals and cereals grown with arboriculture was found which is due to the similarity between these two classes.With this automatic land cover model, we have been able to produce the cereal maps of the last 12 agricultural years. This approach could be also used in the future to obtain a cereal map as early as February.
Unravelling the formation paths of amorphous hydroxyaluminosilicates and hydrous ferric silicates: Evidence from silicon isotopes
Authors: Stamm Franziska M. , Baldermann Andre , Frick Daniel A. , Hippler Dorothee , Dietzel Martin
Published: February 2023

Silicate mineral weathering and the resulting formation of clay minerals are key processes at the Earth’s surface. Reverse weathering reactions regulate the evolution of ocean pH and chemistry, atmospheric carbon dioxide budget, soil formation and associated nutrient and element transfer within local and global biogeochemical cycles. A key element released during weathering processes is silicon (Si), that enters the biogeochemical cycle as dissolved silicic acid (Si(OH)4 or DSi). During the transport of DSi through the hydro-, bio-, pedo- and lithosphere towards the ocean, DSi is involved in the formation of new silicate minerals (i.e., clay minerals) in particular in the critical zone (CZ). Here, DSi is frequently precipitating as gel-like, amorphous phases such as short range ordered hydroxyaluminosilicate phases (HAS: e.g., allophane) or as hydrous ferric silicates (HFS: e.g., hisingerite). These highly reactive minerals are known precursors to the formation of important soil clay minerals e.g., within the smectite group.The individual reaction pathways and the environmental controls underlying HAS and HFS formation within the CZ are not yet well constrained. Si isotope fractionation throughout HAS and HFS formation is a key tool to decode and assess such enigmatic reaction mechanisms. Therefore, a series of allophane-hisingerite precipitation experiments has been performed to investigate Si isotope fractionation to potentially resolve mechanisms and conditions underlying the formation of HAS and HFS phases. Kinetic and equilibrium Si isotope fractionation between reactive fluid and solid phases are studied at high temporal resolution. Isotope exchange mechanisms are investigated using the three-isotope method, which is a novel proxy to trace the direction and the progress of low-temperature water-mineral/rock interactions.
New insights into the deformation history of the Brenner Fault by the application of ESR thermochronometry
Authors: Argante Valentina , Tsukamoto Sumiko , Tanner David Colin , von Hagke Christoph , Brandes Christian
Published: February 2023

The Brenner Fault (BF) is an extensional low-angle fault in the eastern Alps that borders the western edge of the Tauern Window. The BF was instrumental in the exhumation of the latter, allowing the formation of the tectonic window by the uplift of the footwall. It consists of a wide shear zone, dipping to the west by an angle of 25-30°, overprinted by a brittle and steeper fault zone with a few metres thickness.  Exhumation and cooling history of its footwall has been investigated by several low temperature thermochronometry approaches, which have defined the Neogenic deformation history, using the zircon and apatite U-Th/He dating methods (Wolff et al. 2021). Because of the lack of thermochronological methods able to date the thermal history of the rocks during Quaternary, the most-recent knowledge of this fault activity has not yet been defined. New studies have shown the possible application of ESR dating on quartz as an ultralow-temperature thermochronometer, characterized by a closure temperature of 30°-90°C, and dating range of 103-107 years that is therefore a useful tool to reconstruct the tectonic deformation of the upper crust during the Quaternary. In this work, we show new structural data and the first results of ESR thermochronometry on quartz applied to rocks of BF collected across both the shear and fault zones. An en-echelon system of normal faults can be distinguished within the continuous N-S striking main fault, suggesting the probable start of brittle deformation or a following deformation phase overprinted the previous one. Moreover, ESR measurements of ten samples collected across the BF show that the ESR ages of quartz get younger toward the Tauern Window, in accordance with fission track and (U-Th)/He ages. The ESR ages indicate the Quaternary exhumation of the BF, i.e. the youngest activity of the BF. Our results promise the successful application of ESR thermochronometry in defining the youngest deformation histories of Neogenic faults in the Alpine chain.
Microphysics of brittle-plastic transition and origin of Goetze’s criterion
Authors: Liu Dong , Brantut Nicolas
Published: February 2023

The rheology of rocks transitions from a localized brittle behaviour to a distributed plastic behaviour as the pressure and temperature increase with depth in the crust. Goetze's criterion defines this brittle-plastic transition as the depth at which the material strength becomes lower than the effective confining stress. However, such a criterion is not universal and seems material-dependent. In this work, we use a micromechanical model based on grain-scale frictional sliding cracks that can extend either as tensile “wing” cracks or as planar plastic zones (dislocation array), and we analyse the micro-mechanical controls of the brittle-plastic transition in rocks. We assume a constant confining stress loading condition consistent with most laboratory rock deformation tests and derive the corresponding stress-strain evolution. Our results indicate that apart from the confining stress and the ratio of fracture toughness and shear yield strength, the friction coefficient and frictional cohesion also play a significant role in the brittle-plastic transition. Low friction coefficients tend to promote a more brittle behaviour which is consistent with observations in talc and phyllosilicates. Moreover, we show that the presence of pore fluids may also extend the brittle regime. Our microphysical analysis shows that the overall success of Goetze’s criterion in rocks likely arises from the fact that most rocks share similar toughness, shear yield stress, and friction coefficient.
Sensitivity of of coupled climate and ice sheet of modern Greenland to atmospheric, snow and ice sheet parameters
Authors: Lang Charlotte , Edwards Tamsin , Owen Jonathan , Sherriff-Tadano Sam , Gregory Jonathan , Ivanovic Ruza , Gregoire Lauren , Smith Robin S.
Published: February 2023

As part of a project working to improve coupled climate-ice sheet modelling by studying the response of ice sheets to changes in climate across different periods since the Last Glacial Maximum, we present an analysis of an ensemble of coupled climate and ice sheet simulations of the modern Greenland using the FAMOUS-BISICLES model and statistical emulation.FAMOUS-BISICLES, a variant of FAMOUS-ice (Smith et al., 2021a), is a low resolution (7.5°X5°) global climate model that is two-way coupled to a higher resolution (minimum grid spacing of 1.2 km) adaptive mesh ice sheet model, BISICLES. It uses a system of elevation classes to downscale the lower resolution atmospheric variables onto the ice sheet grid and calculates surface mass balance using a multilayer snow model. FAMOUS-ice is computationally affordable enough to simulate the millennial evolution of the coupled climate-ice sheet system as well as to run large ensembles of simulations. It has also been shown to simulate Greenland well in previous work using the Glimmer shallow ice model (Gregory et al., 2020).The ice sheet volume and area are sensitive to a number of parametrisations related to atmospheric and snow surface processes and ice sheet dynamics. Based on that, we designed a perturbed parameters ensemble using a Latin Hypercube sampling technique and ran simulations with climate forcings appropriate for the late 20th century.Gaussian process emulation allows us explore parameter space in a more systematic and faster way than with more complex earth system models and make predictions at input parameter values that are not evaluated in the simulations. We find that the mass balance is most correlated to three parameters:n, the exponent in Glen’s flow law, and beta, the coefficient of the basal drag law, both influencing the amount of ice lost through discharge
rho_threshold, a parameter setting the minimum value the dense firn albedo can possibly reach
Finally, using a history matching approach, we built an implausibility metric (based on surface mass balance, ice volume loss, near-surface and sea-surface temperature) to identify the regions of the parameter space that produce plausible runs.
Modulation of Maritime Continent convection by the MJO: differences between parametrized and explicit convection
Authors: Shipley Dan , Howard Emma , Woolnough Steven
Published: February 2023

Convection over the Maritime Continent has large impacts for local extreme weather, as well as for global weather and climate. However, this convection and its impacts are poorly represented in current weather and climate models. This is largely due to complex multi-scale interactions between convection and the ocean, intricate island coastlines and topography, equatorial waves, and larger-scale dynamics such as the Madden-Julian oscillation (MJO). In order to better understand the modulation of convection by the MJO, and its representation in current models, we developed a new modelling suite that couples the Met Office Unified Model to a thermodynamic mixed-layer ocean model with additional corrections to account for ocean dynamics. This allows two-way interactions between the atmosphere and ocean on convection-relevant timescales without the expense of a full dynamical ocean model. We present results from simulations of 10 DJF seasons over the Maritime Continent at grid spacings of 12km (with a mass flux convection scheme) and 2km (without).  We investigated the modulation of large-scale convective heating and moistening by MJO phase in both models. We show that: The 2km suite has more variability by MJO phase, and this variability is more realistic than that in the 12km suite when compared to observational data; 
There is more variability in the type of convection (defined by the shape of heating/moistening profiles) between MJO phases in the 2km suite; 
The dominant variation is between different types of convection in the two suites. 
We also present preliminary results on the modulation by the MJO of basic properties of the cloud field like feature size, and feature isotropy.  
Indirect and direct impacts of Typhoon In-Fa (2021) on heavy precipitation in inland and coastal areas of China: Synoptic-scale environments and return period analysis
Authors: Wang Liangyi , Gu Xihui , Slaster Louise J. , Lai Yangchen , Zhang Xiang , Kong Dongdong , Liu Jianyu , Li Jianfeng
Published: February 2023

Typhoon In-Fa in 2021 produced an indirect heavy precipitation event (HPE) in central China well over a thousand kilometers away from its center, as well as a direct HPE in eastern China near its eyewall, inner and outer spiral rainbands. Both indirect and direct HPEs of Typhoon In-Fa caused severe impacts on the society. However, the synoptic-scale environments and the impacts of return period estimations of these HPE events remain poorly understood. Here, we first evaluated the spatio-temporal evolution of the two HPEs indirectly and directly induced by Typhoon In-Fa, then examined the synoptic patterns during Typhoon In-Fa for both HPEs in central and eastern China, and finally analyzed how the Typhoon In-Fa-induced HPEs affected local return period estimations of precipitation extremes. Our results show that the remote HPE over central China ~2,200 km ahead of Typhoon In-Fa was a typical predecessor rain event (PRE). A low-level southeasterly jet conveyed abundant moisture from the vicinity of Typhoon In-Fa to central China. Abundant moisture experienced strong convergence and was forced ascent, which caused frontogenesis on the windward slope due to the impacts of orographic forcing, thereby the occurrence of PRE in central China. The PRE occurred beneath the equatorward entrance of the upper-level westerly jet. Meanwhile, Typhoon In-Fa and the PRE favored divergently and adiabatically driving outflow in the upper level, and thus intensified the upper-level westerly jet. In eastern China, the HPE occurred in areas situated less than 200 km from Typhoon In-Fa’s center and left of Typhoon In-Fa’s propagation. The persistent HPE was primarily due to the long duration and slow movement of Typhoon In-Fa. On the one hand, favorable thermodynamic and dynamic conditions, and abundant atmospheric moisture favored the maintenance of Typhoon In-Fa intensity. On the other hand, a saddle-shaped pressure field in the north of eastern China and peripheral weak steering flow impeded Typhoon In-Fa’s movement northward. From the perspective of hydrological impacts, indirect and direct HPEs induced by Typhoon In-Fa led to decreases in return period estimates of HPEs (especially in central China), indicating that such extreme HPEs might increase the failure risk of engineering operations. These results suggest that anomalous HPEs remotely triggered by TCs require improved early warnings, and that more attention should be paid to such HPEs when estimating the design values of hydraulic infrastructure.
Minimal Modelling of Internal Macroeconomic Variability
Authors: Ohara Daniel , Ghil Michael
Published: February 2023

In the climate sciences, highly simplified nonlinear models are useful tools for understanding and discussing tipping points. However, the economic models used to study their coupling to the economy, as in Integrated Assessment Models (IAMs), are typically linear and represent an inertia-free economy in equilibrium. This representation is challenged by persistent unemployment, recessions, and changing economic institutions. Therefore, we investigate the non-equilibrium dynamics of the economy and the corresponding tipping from equilibrium to so-called endogenous business cycles. To this end, we build a basic Solow-type equilibrium growth model that incorporates, in a highly simplified manner, frictions and delay in the labor system. When the delay exceeds a critical value of 3.4 days, business cycles with periodic unemployment and recessions arise in our minimal business cycle (MinBC) model. Given a dynamic investment mode, the MinBC's cyclic economy responds to external forcing asymmetrically throughout the cycle. Advanced time series analysis methods are applied to macroeconomic data sets to evaluate the realism of the model's response, with encouraging results.Our study is a step towards understanding the evolution of the sources of internal economic variability. Such an understanding is needed to represent the extent of coupling between the earth system and the economy.
European hydroclimate variability of the past 400 years based on tree-ring isotopes
Authors: Freund Mandy , Helle Gerhard , Balting Daniel , Ballis Natasha , Schleser Gerhard , Cubasch Ulrich
Published: February 2023

In recent decades, Europe has experienced more frequent flood and drought events. However, little is known about the long-term, spatiotemporal hydroloclimatic changes across Europe. We show the first climate field reconstruction spanning the entire European continent based on tree-ring stable isotopes. A pronounced seasonal consistency in climate response across Europe leads to a unique, well-verified spatial field reconstruction of European summer hydroclimate back to 1600. We find distinct phases of European hydroclimate variability as possible fingerprints of solar activity (coinciding with the Maunder Minimum and the end of the Little Ice Age), pronounced decadal variability and a long-term drying trend from the mid 20th century. The recent European summer conditions are highly unusual in a multi-century context and unprecedented for large parts of central and western Europe.
Discerning fracturing and constraining hydraulic properties from the characteristics of free pressure oscillations in boreholes
Authors: Jimenez Martinez Victoria Alegria , Renner Joerg
Published: February 2023

The creation of fractures in boreholes by hydraulic stimulation is of importance for enhancing fluid transport in the context of geothermal reservoirs. Detecting whether a fracture is created and evaluating its capacity to transport fluid are usually performed by locating the acoustic emissions generated during the rock failure and by comparing the hydraulic properties before and after this type of hydraulic stimulation using pumping tests, respectively. However, free oscillations, exerted by rapid changes in pumping parameters, can be used as well to detect the existence of a fracture and to evaluate its permeability. The diagnostic properties of free pressure oscillations are their spectral components, i.e., frequency and damping coefficient. The hydraulic system, which includes technical equipment such as tubes and hoses, and the rock formation, which can be tight or leaky. In a tight system, the free pressure oscillations are attenuated by the viscous interaction of the fluid and the borehole wall and the local coupling of the fluid compression and deformation of the borehole due to the pressure variation. In a leaky system, the attenuation of free pressure oscillations includes fluid exchange between the borehole and the hydraulic conduits of the rock. We developed an analytical solution starting from the dispersion relation of fluid-flow waves in a tight borehole by accounting for the fluid exchange as a modified boundary condition. Deviation of spectral components of observed oscillation from the analytical solution for a tight borehole is an indication that the free pressure oscillations contain information of the hydraulic properties of the penetrated formation. The oscillations typically last for tens of seconds, which allows assessing the success of the stimulation operation on a near-real-time basis. We analyzed the characteristics of free operations recorded in boreholes during several hydraulic stimulation campaigns. We investigated the evolution of the spectral components in the course of the stimulation and with changes in mean injection pressure and obtained transmissivity values that favorably compare to the results of conventional analyses.
Unsupervised Clustering applied on Raman spectra of dispersed carbonaceous material: a case history from the Paris Basin (France)
Authors: Schito Andrea , Vergara Sassarini Natalia Amanda , Gasparrini Marta , Michel Pauline , Corrado Sveva
Published: February 2023

In the last decades, the use of Raman spectroscopy on dispersed carbonaceous material in rocks has become a promising tool for geothermometry and thermal maturity assessment. In diagenesis the main problem is linked to organofacies composition and the need of time-consuming optical classification (Henry et al., 2019, Sanders et al., 2022). In this work, three different methods of clustering analysis on Raman spectra were tested as a potential approach to recognize the three main organofacies (amorphous organic matter, translucid and opaque phytoclasts) that characterize a set of 27 organic-rich samples from the Lower Toarcian source rock interval (Schistes Carton) of the Paris Basin (France).Raman analyses were performed on concentrated organic matter obtained by acid attacks, with around 60 counts for each sample. Principal Component Analysis (PCA) was applied to reduce the dimensionality of each dataset on a 2-D score-plot. Unsupervised clustering was then performed by using three different clustering algorithms: k-means, Gaussian Mixture Models (GMM), and Density-Based Spatial Clustering for Applications with Noise (DBSCAN). The main task of these algorithms is to correctly assign the number of clusters, their size, orientation, and distribution in the score-plot that related to the heterogeneities in organofacies composition.Results show the best performances are achieved through the application of GMM clustering that can successfully determine cluster’s geometry and optimal numbers with an accuracy mostly higher than 80% for the translucid phytoclasts group, that is the target for thermal maturity assessment.  This is a preliminary attempt showing promising application for unsupervised learning techniques coupled with Raman spectroscopy that could be applied in industrial routinely organic matter characterization or in the analysis of big dataset in both Earth and planetary sciences. Henry, D. G., Jarvis, I., Gillmore, G., & Stephenson, M., 2019. Raman spectroscopy as a tool to determine the thermal maturity of organic matter: Application to sedimentary, metamorphic and structural geology. Earth-Science Reviews 198, 102936.Sanders, M. M., Jubb, A. M., Hackley, P. C., & Peters, K. E., 2022. Molecular mechanisms of solid bitumen and vitrinite reflectance suppression explored using hydrous pyrolysis of artificial source rock. Organic Geochemistry 165, 104371.
A two-species model of aeolian saltation incorporating cooperative splash
Authors: Chen Yulan , Pähtz Thomas , Tholen Katharina
Published: February 2023

Most aeolian sand transport models incorporate a so-called “splash function” that describes the number and velocity of particles ejected by the splash of an impacting particle. It is usually obtained from experiments or simulations in which an incident grain is shot onto a static granular packing. However, it has recently been discovered that, during aeolian sand transport, the bed cannot be considered as static, since it cannot completely recover between successive impacts. This leads to a correction of the splash function accounting for cooperative effects, which is responsible for an anomalous third-root scaling of the sand flux with the particle-fluid density ratio s [1]. Here, we present a two-species saltation model that incorporates this correction. In contrast to the model by [1], it does not only quantitatively reproduce sand fluxes but also transport thresholds from measurements and discrete element method-based sand transport simulations across several orders of magnitude of s.[1] Tholen, Pähtz, Kamath, Parteli, Kroy, Anomalous scaling of aeolian sand transport reveals coupling to bed rheology, Physical Review Letters, accepted.
Monitoring steam content in the crust with seismic noise
Authors: Sánchez-Pastor Pilar , Wu Sin-Mei , Hokstad Ketil , Kristjánsson Bjarni , Drouin Vincent , Gunnarsson Gunnar , Ducrocq Cecile , Rinaldi Antonio , Obermann Anne , Wiemer Stefan
Published: February 2023

Seismic noise interferometry (SNI) is based on the computation of seismic response by extracting correlated wavefields from continuous seismic recordings. This seismic response is understood as the Green’s function of the propagation medium and it is typically used to image the subsurface. Furthermore, a regular retrieval of this magnitude in time enables the identification of changes in the structural and mechanical properties of the subsurface and therefore, it can be also used for monitoring purposes.Here, we use SNI to monitor the steam content in geothermal reservoirs. The massive extraction of fluids commonly causes a pressure drop in the rock matrix and land subsidence in the surroundings of production areas. Furthermore, the boiling point decreases yielding decompression boiling. Estimating the steam fraction at depth is challenging especially in reservoirs with two-phase fluids. In this work, we focus on the Hengill geothermal area (Iceland), where the steam ratio has increased by around 30% in the last 10 years due to the harnessing of geothermal energy.In this area, we measure the land deformation with synthetic aperture radar interferometry (InSAR) and estimate seismic velocity changes with SNI. We observe that both magnitudes linearly decrease in the long term accordingly to the energy production. Besides, we model the expected seismic velocity drop with in-situ borehole data (temperature, pressure, and steam ratio) and conclude that the seismic velocity drop might be related to the steam evolution within the reservoir. These results offer an innovative way of estimating the steam content in the crust with a surface and non-invasive technique.
Improving Dual-Polarization Radar-based rainfall estimation using Long Short-Term Memory Neural Networks
Authors: Lin Jiun-Liang , Hsu Chia-Yu , Chang Li-Chiu
Published: February 2023

Extreme hydrological events, which are highly concerned by local governments, hydraulic units and hazard response centers due to their potential to bring heavy rainfall and cause serious floods, have frequently occurred and impacts on Taiwan urban area in recent years under the circumstance of climate change and global warming. The frequent occurrence of high intense storm always leads to flooding-related disasters within a short period, which makes rainfall monitoring a disaster prevention. Therefore, this study utilizes Long Short-Term Memory Neural Networks (LSTM) and Back Propagation Neural Networks (BPNN) to extract the characteristics of radar observations and forecast rainfall with time 1-step-ahead to 6-step-ahead (T+1~T+6) in Taiwan’s capital, Taipei City. The data collection was included in the Shulin dual-polarization radar (RCSL) observations, such as differential phase shift, specific differential phase, reflectivity and doppler radial wind field, and rain gauge data from May 2021 to November 2021 in the Taipei City. With a view to capturing the movement of hydrometeors continually changes within the time step, an algorithm which can calculate velocity and direction of specific hydrometeors on two-dimensional matrix were developed and applied to simulate location of the specific hydrometeors on n-step-ahead (T+n). Finally, the rainfall forecast can be achieved by using the simulated location of specific hydrometeors and its physical properties from radar observations as input data to fit rainfall from the gauge. This study aims to investigate the relationship between short-duration rainfall and radar observations by artificial neural network (ANN), and forecast the rainfall  within a short period. Keywords: Dual-Polarization Radar; Rainfall Estimation; Artificial Intelligence (AI), Artificial neural network (ANN); Long Short-Term Memory Neural Networks(LSTM)