bluuebunny/crossref_metadata_2025 huggingface dataset:
Perceived midlatitude jet waviness response to polar warming is sensitive to warming structure and metric choice
Authors: Geen Ruth , Thomson Stephen , Screen James , Vallis Geoff
Published: February 2023

Arctic amplification has been proposed to influence midlatitude weather via a range of pathways. One hypothesis that has garnered wide public interest is that the weakening of the midlatitude temperature gradient due to Arctic warming causes larger meanders in the jet stream and so more intense weather extremes. However, previous work with idealized model simulations indicated that polar warming reduces waviness. A variety of metrics have been developed to describe jet waviness, with some focused on jet geometry and others on the magnitude of the associated geopotential anomalies. Recent studies analyzing sea-ice loss and global warming simulations indicate that the response to polar warming may depend on its depth, with deeper warming having a larger effect on midlatitudes. Here we perform a variety of dry idealized model simulations in which we apply polar warming of different depths and latitudinal extents and assess the behavior of these different metrics. Eddy heat transport decreases regardless of how polar warming is applied. However, unexpectedly we find that metrics relating to geometry (jet sinuosity, meander area) indicate a robust increase in jet waviness with polar warming. Meanwhile Local Wave Activity suggests increased waviness if warming is confined to the poles, but decreased waviness if warming extends into the midlatitudes. The apparent disagreement between metrics can be reconciled by assessing the changes in midlatitude geopotential gradient in the different simulations. Overall, these idealized simulations indicate that polar amplification could cause an increase in jet meandering, characterized by a shift of geopotential anomalies to smaller spatial scales and lower frequencies. However, the heat transport achieved and magnitude of pressure anomalies generated depend predominantly on the equator-to-pole temperature difference and geopotential gradient. Implications for weather extremes are discussed.
Long-term impact of urban areas on meteorological conditions: focus on cloud/rain microphysics and convection
Authors: Villalba-Pradas Anahí , Karlický Jan , Huszár Peter
Published: February 2023

Urban environments not only affect the warming rate over cities through the so-called urban heat island (UHI) but also induce changes in other relevant meteorological variables. This study aims to evaluate the impact that different combinations of urban, microphysics and convective parameterizations have on a number of meteorological variables, including temperature, wind, and those related to cloud/rain microphysics. Simulations were performed using the WRF model with a domain at 9km horizontal resolution centered over Prague covering central Europe for the 2008-2017 period. The urban schemes used include bulk, the single-layer urban canopy model (SLUCM), and the multilayer urban models (BEP-BEM) with a building energy model including anthropogenic heat due to air conditioning. We further consider another scenario in which the urban land use category is fully replaced by a rural one (NO URBAN). Besides, we also used two different options for the microphysics and convective schemes. These parameterizations are the Purdue and Lin and the WRF Double moment 6-class scheme for the microphysics option, and the Grell3D and the Grell and Freitas schemes for the convective scheme. Our results show that the inclusion of urban canopy schemes leads to an increase in temperature and a decrease in wind speed as well as to changes in other relevant meteorological values such as cloudiness and precipitation, which also depend on the microphysics and convective scheme used.
2D mineral prospectivity mapping of hand specimen and outcrop walls using AHS and pXRF data in Bockau
Authors: Köhler Martin , Rizatdinova Nailia , Knobloch Andreas , de la Rosa Roberto
Published: February 2023

The Goldeneye project combines different sensing technologies with proximal sensing to produce reference calibrated mineralogical maps through data fusion. In order to develop mineral detection applications, rock specimens, taken from an outcrop in Bockau (Erzgebirge, Germany), are analyzed with active hyperspectral scanning (AHS) as well as portable X-ray fluorescence (pXRF) devices. The received data is analyzed by means of artificial intelligence in order to develop an approach to automatically map the minerals with the samples. The analysis is carried out in advangeo® 2D Prediction, developed by Beak Consultants GmbH. Tin concentrations derived from pXRF measurements and AHS data from 2/3 of the specimen surface serve as training and validation data of the artificial intelligence algorithm (artificial neural networks). As a result, we developed a prediction model for the distribution of tin and its associated mineral cassiterite throughout the rock specimen, which allows to detect the mineral potential of hand specimens and larger outcrops in a fast and reliable manner.The paper has been prepared in the frame of the Horizon 2020 co-funded project GOLDENEYE, which has received funds through the Grant Agreement 869398.
Pressure-driven upper-mantle flow in the Indo-Atlantic Realm since the Upper Jurassic inferred from continent-scale hiatus surfaces and oceanic spreading rate variations
Authors: Vilacís Berta , Hayek Jorge N. , Stotz Ingo L. , Bunge Hans-Peter , Friedrich Anke M. , Carena Sara , Clark Stuart R.
Published: February 2023

Mantle convection is a fundamental process responsible for shaping the tectonic evolution of the Earth. It is commonly perceived that mantle convection is difficult to constrain directly. However, it affects the horizontal and vertical motion of the lithosphere. The former is observed in the spreading rates, while the latter leaves various imprints in the geological record. In particular, the positive surface deflections driven by mantle convection create erosional/non-depositional environments, which induce gaps (hiatus) in the stratigraphic record (i.e., an absence or thinning of a sedimentary layer). Modern digital geological maps allow us to map long-wavelength no-/hiatus surfaces at continental scale systematically.Here we compare our continent-scale hiatus mapping to plate motion variations in the Atlantic and Indo-Australian realms from the Upper Jurassic onward. In general, we find the datasets correlate except when plate boundary forces may play a significant role. There is a timescale on the order of a geologic series, ten to a few tens of millions of years (Myrs), between the occurrence of continent-scale hiatus and plate motion changes. This is consistent with the presence of a weak upper mantle. Furthermore, we find significant differences in the spatial extent of hiatus patterns across and between continents, which means they cannot simply be explained by eustatic variations but should be linked to variations in the upper-mantle flow.Our results highlight the importance of geological datasets to map the temporal evolution of geodynamic processes in the deep Earth. Also, they imply that different timescales for convection and topography in convective support must be an integral component of time-dependent geodynamic Earth models. Studies of horizontal and vertical motion of the lithosphere to track past mantle flow would provide powerful constraints for adjoint-based geodynamic inverse models of past mantle convection.
Using FAIR and Open Science practices to better understand vegetation browning in Troms and Finnmark (Norway)
Authors: Iaquinta Jean , Fouilloux Anne
Published: February 2023

In most places on the planet vegetation thrives: it is known as “greening Earth”. However in certain regions, especially in the Arctic, there are areas exhibiting a browning trend. This phenomenon is well known but not fully understood yet, and grasping its impact on local ecosystems requires involvement of scientists from different disciplines, including social sciences and humanities, as well as local populations. Here we focus on the Troms and Finnmark counties in northern Norway to assess the extent of the problem and any link with local environmental conditions as well as potential impacts. We have chosen to adopt an open and collaborative process and take advantage of the services offered by RELIANCE on the European Open Science Cloud (EOSC). RELIANCE delivers a suite of innovative and interconnected services that extend the capabilities of the European Open Science Cloud (EOSC) to support the management of the research lifecycle within Earth Science Communities and Copernicus Users. The RELIANCE project has delivered 3 complementary  technologies: Research Objects (ROs), Data Cubes and AI-based Text Mining. RoHub is a Research Object management platform that implements these 3 technologies and enables researchers to collaboratively manage, share and preserve their research work. We will show how we are using these technologies along with EGI notebooks to work open and share an executable Jupyter Notebook that is fully reproducible and reusable. We use a number of Python libraries from the Pangeo software stack such as Xarray, Dask and Zarr. Our Jupyter Notebook is bundled with its computational environment, datacubes and related bibliographic resources in an executable Research Object. We believe that this approach can significantly speed up the research process and can drive it to more exploitable results. Up to now, we have used indices derived from satellite data (in particular Sentinel-2) to assess how the vegetation cover in Troms and Finnmark counties has changed. To go a bit further we are investigating how to relate such information to relevant local parameters obtained from meteorological reanalysis data (ERA5 and ERA5-land from ECMWF). That should give a good basis for training an Artificial Intelligence algorithm and testing it, with the objective of getting an idea about the possibility of “predicting” what is likely to happen in the near future with certain types of vegetation like mosses and lichens which are essential for local populations and animals.
Land evaporation biases link to East Asian rainfall shifts across AMIP simulations
Authors: Geen Ruth , Pietschnig Marianne , Agrawal Shubhi , Dey Dipanjan , Lambert F. Hugo , Vallis Geoffrey
Published: February 2023

State-of-the-art models show significant climatological biases in their simulation of East Asian Summer Monsoon (EASM) rainfall, with biases even more pronounced in atmosphere-only simulations versus simulations with a coupled-ocean. It has further been noted that systematic evapotranspiration biases occur locally over East Asia, and globally over land, in simulations both with and without a coupled ocean. Here, we explore a possible role for evapotranspiration in EASM precipitation biases. Idealized model simulations are presented in which the parameterization of land evaporation is modified. The results suggest a feedback whereby excessive evapotranspiration over East Asia can result in cooling of land, a weakened monsoon low, and a shift of rainfall from the Philippine Sea to China, moistening land and further fueling evapotranspiration. Cross-model regressions against evapotranspiration over China indicate that a similar pattern of behavior is seen in Atmosphere Model Intercomparison Project (AMIP) simulations. In AMIP, the feedback is not explained by a too-intense global hydrological cycle or by differences in radiative processes. Analysis of land-only simulations indicates that evapotranspiration biases are present even when models are forced with prescribed meteorological conditions. These biases are strengthened when the land model is coupled to the atmosphere, suggesting a role for land-model errors in driving atmospheric biases. Coupled atmosphere-ocean models are shown to have similar evapotranspiration biases to those in AMIP over China, but different precipitation biases, including a northward shift in the Intertropical Convergence Zone over the Pacific and Atlantic oceans.
Orogenic polarity, paleo-magnetic constraints and updated geochronology of high to ultra high-pressure metamorphism: towards a re-interpretation of the evolution of the French Variscan belt?
Authors: Lardeaux Jean-Marc
Published: February 2023

In mountain belts, one the one hand, the method to restore the paleopositions of landmasses, and thus oceanic domains, is paleomagnetism, combined with high-resolution geochronological data. As far as the Palaeozoic is concerned, we are fortunate to benefit of the so-called unified full plates reconstruction models (i.e. paleomagnetic databases consistent with coherent plate boundaries kinematics, mantle dynamics and geologic features, see for example Domeier and Torsvik, 2017 for a general discussion).On the other hand, deciphering orogenic polarity requires the combination of different geophysical methods. Regarding the European Variscan belt, a synthetic overview of results and interpretations of various methods of geophysical imagery is now available ( Edel et al, 2018; Schulmann et al., 2022).These two types of data constitute robust points of reference that any orogenic evolution model must respect at least in the first order.In the last decade, in the French Variscan belt, significant advances linking petrological and geochronological records have been performed, especially on high to ultra-high pressure metamorphic rocks. In addition, new observations have confirmed the occurrence and extension of magmatic arcs and back-arcs systems active during Devonian and Carboniferous times.We present and discuss a review of all these new data and their confrontation with the available robust paleomagnetic and geophysical crustal-scale constraints. This analysis leads us to a revision, and sometimes a radical re-evaluation, of the orogenic evolution models hitherto proposed to interpret the evolution of the French part of the European Variscan belt.References:Edel JB, Schulmann K, Lexa O, Lardeaux JM. 2018. Late Palaeozoic palaeomagnetic and tectonic constraints for amalgamation of Pangea supercontinent in the European Variscan belt. Earth Sciences Review, 177:589−612Domeier M, Torsvik TH. 2017. Full-plate modelling in pre-Jurassic time. Geological Magazine, 156(2): 261−280.Schulmann, K., Edel, J.B., Martinez-Catalàn, J.R., Mazur, S., Guy, A., Lardeaux, J.M., Lexa, O., Ayarza, P., Palomeras, I. 2022. Tectonic evolution and global architecture of the European Variscan belt constrained by geophysical data. Earth Sciences Review, 234, 104195.
Integrated imaging of a landslide as a result of 4 years of observations – A case study from Outhern Carpathians
Authors: Marciniak Artur , Majdański Mariusz , Kowalczyk Sebastian , Cader Justyna , Nawrot Adam , Owoc Bartosz , Stan-Kłeczek Iwona , Górszczyk Andrzej , Gajek Wojciech , Oryński Szymon , Czarny Rafał
Published: February 2023

The problem of landslides is one of the greatest challenges in geohazard research. Due to their unpredictability, and complicated genesis, their detailed and accurate observation is necessary. Despite many studies on the subject, a general scheme for their recognition has still not been developed. An additional, and important fact that has recently been observed is the impact of the current state of the climate, and the human response to it. In the presented research results, an example where anthropogenic factors can have a significant impact on the evolution of a creeping landslide is described. As a result of changes in precipitation over years, artificial snowmaking is necessary to extend and even maintain the ski season on ski slopes and results in the unique characteristics of those landslides. In this presentation we shows the results of 4 years of geophysical observations, integrating multiple methods from geophysical imaging and remote sensing to determine the characteristics of the landslide, its changes and potential danger. The methods used, such as passive seismological monitoring, seismic tomography, electrical resistivity tomography, reflection imaging, terrestrial laser scanning and electromagnetic slingram in a time-lapse scheme allowed us to obtain an image of a temporally and spatially variable structure with remarkable accuracy. Additionally, there were also made an AMT profile with deep recognition range. The results obtained and their joint interpretation can serve as a reference in the study of similar landslide cases, where anthropogenic and climatic factors can significantly impact the evolution of such phenomena.This research was funded by the National Science Centre, Poland (NCN), grant number 2020/37/N/ST10/01486.
A large-N passive seismological experiment to unravel the structure and activity of the transcrustal magma system of the Eifel Volcanic Field
Authors: Dahm Torsten ,   Eifel Large-N team
Published: February 2023

The Quaternary east (EEVF) and west Eifel volcanic fields consist of hundreds of distributed scoria cone and explosive maar-diatreme volcanoes fed from reservoirs in the upper mantle and lower crust. Uplifting of the larger EVF region of up to 2 mm/yr is resolved today with modern GNSS and InSAR processing, and the distribution of deformation rates correlate with seismic anomalies and topography at Moho level. The EEVF developed additionally explosive volcanic centres, with a VEI 6 Plinean eruption at the Laacher See volcano (LSV) only 13,000 years ago. The LSV is the second youngest silicic-carbonatitic magma system in the world, with CO2-rich melt erupting from a long-lived (>30.000 years) zoned silicic reservoir at a depth of 5-6 km. The phonolitic centres are today characterised by high CO2 fluxes, fossil CO2-driven diatremes and short-term short wavelength uplift and subsidence. Deep low-frequency earthquakes have been observed beneath the LSV since 2013, suggesting a channel-like connection between the upper mantle and the suspected LSV reservoir, through which magmatic volatiles and possibly fresh melts could migrate upwards.As a uniquely accessible site in central Europe, the Eifel is a prime location to study the transcrustal magma system of intraplate distributed volcanic fields and their appearance in seismological and geodetic data. Therefore, in September 2022 we started a large-scale field experiment with more than 350 temporary seismological stations (Eifel Large-N) complementing the permanent seismic networks, a 100 km long dark fibre DAS campaign for a period of three months, and further densified the network of continuous GNSS and multiparameter stations at the LSV. We report on pre-studies to design the Large-N experiment, the logistical and technical approach to handle the network and data, and show first examples for selected earthquakes, local noise conditions and ambient noise correlations.
U-Net based Methods for the Postprocessing of Precipitation Ensemble Forecasting
Authors: Pic Romain , Dombry Clément , Taillardat Maxime , Naveau Philippe
Published: February 2023

Most Numerical Weather Prediction (NWP) systems use statistical postprocessing methods to correct for bias and underdispersion errors made by ensemble forecasting. This underdispersion leads to an underestimation of extreme events. Thus, many statistical postprocessing methods have been used to take into consideration the extremal behavior of meteorological phenomena such as precipitation. State-of-the-art techniques are based on Machine Learning combined with knowledge from Extreme Value Theory in order to improve forecasts. However, some of the best techniques do not consider the spatial dependency between locations. For example, Taillardat et al. (2019) trains a different Quantile Regression Forest at each location of interest and Rasp & Lerch (2018) uses neural networks with an embedding for the station's information in order to train a global model.The dataset used corresponds to 3-h precipitation amounts produced by the radar-based observations of ANTILOPE and the 17-members ensemble forecast system called PEAROME. The dataset spans over the south of France with a grid resolution of 0.025 degrees. Our method uses a U-Net-like neural network in order to take into account the spatial structure of the data and the output of our model is a parameterized law at each grid point. Among the choices available in the literature, we focused on the Extended Generalized Pareto Distribution  and the truncated logistic with a point mass in 0. The model is trained by minimizing the scoring rules such as the Continuous Ranked Probability Score, the Log-Score or weighted versions of the aforementioned scoring rules. The method developed here is then compared to the raw ensemble as well as state-of-the-art techniques through scoring rules, skill scores and ROC curves.References :L. Pacchiardi, R. Adewoyin, P. Dueben, and R. Dutta. Probabilistic forecasting with generative networks via scoring rule minimization. Dec. 2021. arXiv:2112.08217
M. Taillardat, A.-L. Fougères, P. Naveau, and O. Mestre. Forest-based and semiparametric methods for the postprocessing of rainfall ensemble forecasting. Weather and Forecasting, 34(3):617–634, jun 2019. doi: 10.1175/waf-d-18-0149.1.
Coarse and fine root development of street-tree species in different planting soil substrate
Authors: Becker Joscha N. , Musal Stephan , Ocker Susann , Schütt Alexander , Eschenbach Annette
Published: February 2023

Climate change increases the pressure on urban street trees by limited soil-water availability during extended heat and dry summer periods. Young and freshly planted trees are particularly affected by soil drought since their root system is not well developed and spatially limited to the volume of the initial root ball. The vitality and survival of these trees is strongly dependent on their ability to quickly exploit a larger rooting zone.To investigate early tree development and root growth, we established a field trial in a tree nursery within the metropolitan region of Hamburg, Germany. Three tree species (Amelanchier lamarckii, Quercus cerris and Tilia cordata ‚Greenspire‘) were grown in two soil substrates (loam, sand) in five replicates. After three years, we excavated a defined soil volume radially from each tree trunk, and determined root biomass (coarse > 2 mm, and fine < 2 mm diameter) in three distances and three depths. Results were compared to species-specific allometric equations, derived from stem diameter measurements.While no overall substrate effect appeared for total root biomass, the average fine-root biomass between all species was 59% higher in loam compared to sand. Species wise, A. lamarckii showed 68% lower total root biomass and a lower root spread in sand substrate, compared to loam. This was mainly related to the near complete absence of A. lamarckii‘s coarse roots in sand. In contrast Q. cerris developed larger root biomass in sand substrate, particularly in form of deep fine roots, with a maximum in 60-90 cm depth. This was not reflected in the allometric equation (r = -0.8), indicating a shift in belowground carbon allocation under water stress. Compared to the restricted root system of A. lamarckii and the deep roots of Q. cerris, T. cordata formed an extensive fine root system, with a reduced fine root abundance in sand substrate.We conclude that the rooting-zone exploitation in planting pits is strongly affected by soil substrate and differs between tree species. Particularly Q. cerris invests in a large deep rooting system under enhanced water stress (i.e. in sand substrate), which is not reflected by common allometric equation methods. Ensuring a healthy urban tree population under climate change, therefore requires the combined consideration of adaptive tree species and present urban soil substrates for new tree plantings.
Testing simple approaches to map sediment mobilization hotspots after wildfires
Authors: Parente Joana , Nunes João , Baartman Jantiene , Föllmi Dante
Published: February 2023

The models currently used to predict post-fire soil erosion risks are limited by high data demands and long computation times. An alternative is to map the potential hydrological and sediment connectivity using indices to express the general properties of the landscape under evaluation and map the possible connectivity between the different parts of a catchment.In this study, we aim to answer the question: Do these alternative approaches identify post-fire sediment mobilization hotspots?  To achieve this, we assess the spatial variability distribution of the location of soil erosion hotspots using the Index of Connectivity (IC), Revised Universal Soil Loss Equation (RUSLE model) and the Sediment Export (SE) and compare it to the simulation results of a more complex Landscape Evolution Model (LAPSUS model). Additionally, we evaluate statistical measures of association between the four tools. Furthermore, IC, RUSLE model and SE are used due to their simplistic representation of erosion and ease of application, and the LAPSUS model is used as the best representation of erosion and sediment transport in the study area.Our results show that the three tools (IC, RUSLE model and SE) tested in this study are suitable for identifying sediment mobilization hotspots, i.e., areas where the erosion rates are above the 90th percentile, in recently burnt areas, and differences between their performance are minor. These findings can be considered for post-fire and water contamination risk management, especially for fast prioritization of areas needing emergency post-fire intervention.
Enhancing Flood Risk Management for Urban Coastal Communities Using LiDAR Applications
Authors: Ofterdinger Ulrich , Miller Aaron , Peng Yong , Meneely John , McKinley Jennifer , Bertolotto Michela , Vo Anh Vu , Laefer Debra
Published: February 2023

Within urban centres, underground spaces such as storage areas, transportation corridors, basement car parks, public facilities, retail & office as well as private spaces (e.g., residential basements), present priority risk areas during flood events with respect to timely evacuation.  However, often the location, geometry and volume of these underground spaces is not well known.  Furthermore, these underground spaces are commonly not considered in flood prediction models for urban centres.  At the same time, communicating flood risks and enhancing emergency preparedness poses further challenges.  Thus emergency planners need engaging communication tools to increase community resilience and preparedness to flooding events. Low-cost Mobile Laser Scanning (MLS) and Airborne Laser Scanning (ALS) technologies as well as other remote sensing applications and street view imagery data are becoming increasingly available and affordable, providing high-resolution data for the urban environment.  The presented project focusses on gaining better knowledge of the location and internal geometry of underground spaces in urban centres by using low-cost MLS data. The presented project is developing efficient database approaches to handle the large data sets and to integrate the information into flood prediction models.  These models provide refined information on urban flood levels and flooding rates into the underground spaces, which in turn may be used as part of risk communication tools using low-cost virtual reality applications which provide an immersive experience of flood risk with the aim to better engage communities in emergency preparedness.  The comparison of rapid low-cost high-resolution terrestrial MLS with ALS data for an urban case study site in Belfast (Northern Ireland) highlights the advantages of the rapid low-cost MLS approaches and their use for the detection and surveying of urban underground spaces and the integration of these identified priority flood risks into urban flood models.  Incorporating the identified underground spaces provides more realistic inundation scenarios and enhanced information with regard to accessible evacuation routes to inform flood risk mitigation plans.
The shape of biodiversity through deep time: fossils vs. mechanistic models
Authors: Benton Michael , Cermeño Pedro , García-Comas Carmen , Pohl Alexandre , Williams Simon , Chaudhary Chhaya , Le Gland Guillaume , Müller Dietmar , Ridgwell Andy , Vallina Sergio
Published: February 2023

Palaeontologists have debated for over fifty years whether the fossil record is adequate to document the diversification of life. One view has been that the record is so heterogeneous that any signal would be misleading, whereas others have accepted that the fossils broadly tell the true story. The debate had reached an impasse. In our new work, published in Nature in July 2022, we use a mechanistic model, combining palaeogeographic maps, temperature data, and productivity data to map out biodiversity hotspots through the Phanerozoic. The model runs from the Cambrian to the present day and predicts current marine biodiversity distribution. We argue that this non-biological mechanistic model then gives an accurate plot of the trajectory of palaeobiodiversity and in fact confirms that the fossil record retains a strong signal of reality.

       Two key outcomes of the analysis include an explanation for why life is so diverse today, especially in tropical oceans, and the observation that marine biodiversity never approached equilibrium and indeed is better modelled as an exponential process rather than a logistic/ equilibrium process. First, the five-fold increase in palaeodiversity through the Mesozoic and Cenozoic can be explained by Vermeij’s Mesozoic Marine Revolution, a biological model that focuses on innovation, but also, we suggest, by the long-term stability of biodiversity hotspots since the Triassic and Jurassic. Second, the continuing rise in palaeodiversity from the Triassic to the present day appears to be real, and our model fitting, involving massive iteration to model all kinds of uncertainties, shows that the calibrated logistic model is the best even though marine invertebrate diversity in most of the ocean operates within the exponential growth regime. The calibrated model shows that in tropical biodiversity hotspots, diversity begins to approach equilibrium. Further, our tests show that marine life worldwide never approached saturation, in fact remaining at about 25% of plenitude. This opens up many new ideas about how to comprehend a world of exponentially increasing marine biodiversity.
Propagation of a fluid-induced aseismic crack leads to earthquake swarm migration controlled by fluid volume
Authors: Danré Philippe , Garagash Dmitry , De Barros Louis , Cappa Frédéric , Ampuero Jean-Paul
Published: February 2023

Seismicity migration is one of the most remarkable features of earthquake swarms because of its ubiquity and the wide range of migration durations, velocities and shapes observed. The dynamic properties of swarms, like seismic moment or number of events, are often attributed to fluid circulation, directly or indirectly. However, classical models of fluid pressure diffusion aiming at explaining seismicity triggering and migration show some limitations.  An increasing body of evidence points at an important contribution of fluid-induced aseismic slip during swarms. Moreover, parameters like injection history and fault criticality are expected to intervene. In this work, we use a fracture mechanics framework to show that  earthquake migration can be explained as driven by the propagation of a fluid-induced aseismic slip transient on a rate-and-state fault. This theoretical model predicts a simple linear relation between the seismic migration distance and the square root of the injected fluid volume. This relation is validated by observations in two well-studied seismic sequences induced by injections for geothermal purposes (Basel and Soultz-sous-Forêts), in which the seismicity is mainly clustered around a single surface. In addition, the model helps constrain frictional, hydraulic and structural properties of the fault hosting aseismic slip, and can be reasonably generalized to all fluid-induced earthquake swarms, natural and anthropogenic.
The Impact of Sudden Stratospheric Warmings and Elevated Stratopause Events on the VLF signal in high latitudes
Authors: Schneider Helen , Wendt Vivien , Banys Daniela , Hansen Marc , Clilverd Mark
Published: February 2023

Sudden Stratospheric Warmings (SSW) and Elevated Stratopause (ES) events are atmospheric wave driven winter phenomena, which lead to significant changes in atmospheric dynamics and temperatures. SSWs are characterized by a sudden warming in the stratosphere by up to 90K and a mesospheric cooling by up to 30K. At the same time the background wind decelerates and can even revers which modifies the vertical mass transport. Occasionally SSW are followed by an ES where the stratopause at 50-60 km vanishes and subsequently reforms in elevated altitude ranges of 70-85 km. This leads to a temperature increase of up to 50 K in mesospheric heights. The temperature increase during an ES is accompanied by strongly enhanced positive zonal winds and a downward directed mass transport, which leads to changes in neutral chemistry. Very low frequency (VLF) signals transmission, which is used for long distance communication, is generally conducted from a transmitter station to a receiver station within the so-called wave guide. This is the region between the Earth surface and the bottom side of the ionosphere (~60-90 km), which is behaving as a reflection boundary. Any changes in D-region ionization are able to modify the propagation of the VLF signal.The above described significant changes in wind, temperature and neutral composition during SSW/ES events occur within the VLF reflection heights and likely influence the VLF propagation.For the identification of SSW/ES induced perturbations of the VLF signal we need to remove the typical seasonal variation and outliers caused by noise, technical adjustments or solar events.  For this purpose, a quiet time curve is required, which represents the seasonal VLF signal variation under undisturbed conditions, for each link respectively. We developed the quiet time winter curve with a polynomial fit of the wintertime composite. In preparation for the composite, the VLF data needed to be leveled due to artificial amplitude steps with technical origin in the timeseries. The leveling was done with help of the Pruned Exact Linear Time method. Additionally, outliers have been removed using the Median Absolute Deviation, a method from robust statistics. The developed quiet time winter curve allows us to determine VLF signal perturbations, which we analyze to examine the impact of SSW/ES events on the VLF signal. Furthermore, by studying different links in high latitudes, we want to investigate if there occur longitudinally differences in the VLF signal perturbation as the ES events vary strongly with longitude.
Detection of mining relics (Pingen) using LiDAR technology
Authors: Sterjo Enis , Knobloch Andreas , Köhler Martin , Brosig Andreas
Published: February 2023

From the middle of the 17th to the beginning of the 19th century, tin mining was carried out near Bockau and Aue in the Westerzgebirge. The object of the mining was stratiform mineralization. Near Bockau, (underground) tin mining was first mentioned in documents in 1663 and was active, with interruptions, until the beginning of the 19th century. On an area of more than 2 km², hundreds of dumps and pits, numerous abandoned mines, and historically very remarkable underground objects are known. Mining was preferably carried out near the surface. Despite favourable morphological conditions, hardly any deep adits were built and depths of more than 20 m were rarely reached. In this context, Pingen are abandoned ore pits or prospecting sites, where ores and other mineral resources were mined. Geometrically Pingen resemble round depressions created by the collapse of a mine workings (shaft, adit, underground drift), collapsed due to its age, leaving this relic usually funnel-shaped (down-facing cone), often surrounded by an annular dump (0.5 to 3 m) caused by the lowered surface.The main aim of this application is to identify mining relics (Pingen) using a UAV equipped with LiDAR technology. The LiDAR technology allows to obtain a high-resolution Digital Elevation Model (DEM) and Point cloud of the surveyed area. The DEM is the digital representation of topographic and manmade features located on the surface of the earth.In this framework, a LiDAR survey was conducted in a flight area of about 1,6 km² within the “Bockau” area during August 2022. The surveyed features include the elevations, colorized Point Cloud (RGB values), transparency levels, reflectance values, and number of returns (significant for the penetration of the vegetation). This information was used to derive the final products: DEM and classified Point cloud. Various spatial analyses were conducted and tested on the DEM and Point Cloud to automatically identify the mining relics. Hydrogeological analysis showed to be the best approach for the automatic identification of Pingen. As a result, the ground depressions were identified and nested surfaces were delineated.The automatically identified features were validated by examination of randomly selected samples on the surveyed point cloud, comparison to identified features based on the National dataset of the LiDAR Database and field verification. The validation revealed, that around 90% of the Pingen in the study area were successfully identified with the developed workflow. Other features of interests couldn’t be identified due to the similarity of geometric properties with other topographical features, dense vegetation, erosion etc.The paper has been prepared in the frame of the Horizon 2020 co-funded project GOLDENEYE, which has received funds through the Grant Agreement 869398.
Seasonal Weather Forecast Biases Dependence on Static and Dynamic Environmental Variables in the Alpine Region
Authors: Uttarwar Sameer Balaji , Napoli Anna , Avesani Diego , Majone Bruno
Published: February 2023

Global seasonal weather forecasts have inherent biases compared to observational datasets over mountainous regions. This can be attributed to the model's inaccurate representation of local and global environmental processes on the Earth. In this context, the objective of this study is to assess the variation of seasonal weather forecast biases with respect to static and dynamic environmental variables over the Trentino-South Tyrol region (north-eastern Italian Alps), characterized by complex terrain.The research employs the latest fifth-generation seasonal weather forecast system (SEAS5) dataset produced by the European Center for Medium-Range Weather Forecast (ECMWF), available at a horizontal grid resolution of 0.125° x 0.125° with 25 ensemble members in a re-forecast period from 1981 to 2016. The reference dataset is a high-resolution gridded observation (250 m x 250 m) over the region of interest. The spatiotemporal variation of monthly weather (i.e., precipitation and temperature) forecast biases over the region is inferred using several statistical indicators at observational dataset grid resolution. The static and dynamic environmental variables (i.e., respectively, terrain characteristics and large-scale atmospheric circulation indices) are used univariately to interpret their relationship with monthly weather forecast biases using the linear regression technique. A statistically significant linear relation between monthly weather forecast biases and terrain characteristics, as well as large-scale atmospheric circulation indices, has been found depending on seasonality and ensemble members.Given significant univariate linear correlation, a simple linear bias reduction model is developed and assessed by implementing a random subsampling technique in which the regression parameters are simulated by splitting the data into calibration (70%) and validation (30%). The results reveal a reduction in the monthly weather forecast bias over the region.This study demonstrates that the local and global environmental variables should be explicitly considered in the bias correction and downscaling of the seasonal weather forecasts over complex terrain.
A preliminary test to estimate the carbon sequestration from lake sediments of Sun Moon Lake in Taiwan
Authors: Tsou Pi-Ju , Chen Huei-Fen , Tang Zih-Wei
Published: February 2023

Considering the carbon sinks and carbon sequestration, people often think of forests, trees, oceans. However, the carbon sequestration capacity of the lake was underestimated, until now the change of carbon accumulation in Sun Moon Lake has not been accurately estimated. Sun Moon Lake is the largest natural lake in Taiwan. After the dam was built in 1934, the water source of Sun Moon Lake came from Zhuoshui River from the storage in Wujie Dam . The water depth of the lake increased from 4 meters to 27 meters deep, which makes the lake area to expand suddenly and the sedimentary rate was accelerated. Changes in the environment and human behaviors had caused huge changes in the organic matter of Sun Moon Lake. In this study, the carbon element content was mainly analyzed through sediment cores  in Sun Lake and Moon Lake.  Before the construction of the dam, there were many records of charcoal layers left by the aboriginal people burning forests for reclamation in the core.  The carbon content of the lake can be estimated by the formula CO2e=3.67 * TOC% * BD (g/cm3) * D (cm) * Area (ha). Therefore, we can use this formula to estimate the accumulated carbon sink content in Sun Moon Lake sediments. We try to estimate the carbon storage methods based on inorganic and organic carbon during different periods in the future work. To determine the age control is a critical point in core sediments, so we will use XRF data to reconstruct the timing of typhoon events and human contaminations. The volume of lake sediment can be estimated by the sedimentary rates of cores and seismic profile. Now, we need to measure contents of organic and inorganic carbon for the core sediments. Key words: lake, sediments, carbon, organic, inorganic
Bioclimatic characteristics of the county seat cities in the Moldova - Romania region, outlined by ITU
Authors: Alina Nistor , Bogdan Nistor , Dumitru Mihăilă , Petruț-Ionel Bistricean , Lucian Sfica , Elena Maria Emandi
Published: February 2023

Argument. The bioclimate is one of the most important life factors for humans, influencing a multitude of states, reactions, attitudes, actions and human activities. In the context of the regional warming of the atmosphere, in the conditions where the warming of the atmosphere of the cities of the region is faster and considering that in the cities of Suceava, Botoșani, Piatra Neamț, Iași, Bacău, Vaslui, Focșani and Galaţi there are 1,469,929 inhabitants, this study is necessary and fills a gap in scientific research with the information it brings.Objectives. Having temperature and humidity data series from 10 stations in the 8 cities for the interval January 1, 2009 - December 31, 2022, we bring to the knowledge plan the temporal and spatial coordinates of the ITU for the Moldova region, with the attention focused on the days of the warm season in which ITU was above the thresholds of 66 (the lower limit of the alert threshold) and 80 units (the lower limit of the bio-meteorological discomfort threshold). The objectives of the study are:i) outlining the differences and similarities of the multiannual, annual and daily regime of the ITU, with the identification and determination of the frequency of occurrence of temporal entities in which the value increase exceeded the threshold of 66, respectively 80 units,
ii) the identification of critical intervals from year and day in which the thermo-hygrometric complex can put man in difficulty, iii) finding some explanations related to the spatiality and temporality of the ITU, focusing on the positional, dimensional-urbanistic and synoptic factors, for the cases where the ITU has passed the threshold of 66/80 units.
Results. From all the processed time series, it emerged that the ITU can exceed the daily threshold of 66 units in the April - October interval. The highest frequency of days with ITU above 66 units is reached at all stations during summer days. ITU went up to over 80 units almost exclusively on summer days, most frequently in big cities (Iași - 9.8%, Galați - 2.9%).In the other cities, the ITU passing over 80 units is almost statistically insignificant at the daily level (in Suceava, Botoșani, Piatra Neamț and Focșani, the share of days with ITU ≥ 80 was equal to 0). Between 11-13 and 19-21 and only in the months of June-August ITU exceeded 80 units. In Iași, the share of hours with ITU over 80% was 14.6%, in Galati 9.8%, and in Piatra Neamț only 0.23%. Daily cases with ITU values above 66% held 57.5% of the time and were due to anticyclonic billow baric fields.Conclusions. Through the ITU we demonstrated that in Moldova, on summer days, between 11:00 and 21:00, in a predominantly anticyclonic synoptic context, there is a moderate bio-meteorological risk for the population that goes outside the home during this time.
The Role of Theory and Data in Model Building: from Richardson to machine learning
Authors: Vulpiani Angelo
Published: February 2023

The talk is devoted to a discussion of different  typologies of models: I-  Oversimplified models; II- Models by analogy;  III- Large scale models;IV- Models from data. In the class  I  there is the celebrated   Lorenz model; the  Lotka-Volterra  system  is in the class  II, and it is at the origin of biomathematics.Among the  models in the class III  we have the effective equations used, e.g., in meteorology and engineering,  where only "relevant variables" are taken into account.In the class  IV we find the most interesting (and difficult) problem:the building  of models just from datawithout a reference theoretical framework.
Comparison between a non orographic gravity wave drag scheme and constant level balloons in the QBO region
Authors: Lott Francois , Rani Raj , Podglajen Aurelien , Codron Francis , Guez Lionel , Hertzog Albert , Plougonven Riwal
Published: February 2023

The parameterization scheme that represents gravity waves due to convection in LMDz-6A, the atmospheric components of the IPSL coupled climate model (IPSLCM6), is directly compared to Strateole-2 balloon observations made in the lower tropical stratosphere from November 2019 to February 2020. The input meteorological fields necessary to run the parameterization offline are extracted from the ERA5 reanalysis and correspond to the instantaneous meteorological conditions found underneath the balloons. In general, we find a fair agreement between measurements of the momentum fluxes due to waves with periods less than 1hr and the parameterization. The correlation of the daily values between the observations and the results of the parameterization is around 0.4, which is statistically elevated considering that we analyse around 600 days of data and surprisingly good considering that the parameterization has not been tuned: the scheme is just the standard one that helps producing a Quasi-Biennial Oscillation in the IPSLCM6 model. Online simulations also show that the measured values of momentum fluxes are well representative of the zonally and averaged values of momentum fluxes needed in LMDz-6A to simulate a QBO. The observations also show that longer waves with periods smaller than a day carry about twice as much flux as waves with periods smaller than an hour, which is a challenge since the low period waves that make the difference are potentially in the “grey zone” of most climate models