bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling gully head formation in badlands
Authors: Rossi Mauro , Torri Dino , De Geeter Sofie , Cremer Cati , Poesen Jean
Published: February 2023

Gully erosion is a damaging process not yet sufficiently understood and parameterized. Gully head topographic thresholds are empirical models used to predict the gully head formation. Such model have been used to investigate gully processes mostly in cropland, rangeland and forest. This study extends such modelling approach to badlands. Different badlands (eight sites) have been studied in the Mediterranean environment in Italy and Spain, characterized  by diversified climatic, lithological, and geological settings under different anthropogenic conditioning. Badlands have been characterized by their specific human history in addition to their geomorphological properties. Land use, as part of the human history, strongly affected many badland formation and development, through  extremely impacting land exploitation (usually overgrazing). The effect of geological and geo-morphological processes are usually particularly well visible. While the weakening effect of joints is confirmed, the different geological layer bedding orientation with respect to the slope aspect generates a different development of badland morphologies and different values of gully head thresholds values (as shown in two badlands sites on the same geological material and climate). The selection of Curve Number values, at the base of the introduction of land use into the gully head thresholds, has been more objectively defined in order to reduce arbitrariness in threshold application. The study additionally revises some of the physical basics behind the gully head threshold concept, requiring a description of the soil resistance in terms of frictional and cohesive components. This implies the explicit inclusion of rock fragment into the grain size distribution, which cannot be limited to fine grains. It results into an enriched threshold formulation that allows to describe the condition for gully head initiation and retreat as the result of the tradeoff between the frictional and cohesive components of the soil resistance forces. Eventually, the gully head threshold concept is confirmed and extended to include badlands.
Imaging 3-D electrical conductivity structure under US constrains lateral variations in the mantle water content
Authors: Munch Federico Daniel , Grayver Alexander
Published: February 2023

Electrical conductivity variations provide unique constraints on chemistry, mineralogy, and physical structure of the crust and mantle. As a physical property, conductivity is highly sensitive to the presence of even small amounts of melt and water (i.e., hydrogen). Here, we present a new 3-D electrical conductivity model (MECMUS-2022) derived by inverting data from ~1300 USArray MT stations covering ∼80% of the contiguous United States on a quasi-regular 70-km grid. The use of a novel multi-scale imaging approach and locally refined meshes allows us to consistently incorporate a large range of spatial scales and image 3-D electrical conductivity distribution from the surface down to mantle transition zone. We find conductivity variations that correlate with known continental structures such as due to the active tectonic processes within the western United States (e.g., Yellowstone hotspot, Basin and Range extension, and subduction of the Juan de Fuca slab) as well as the presence of deep roots beneath cratons. We further interpret conductivity variations in terms of the upper mantle water content by coupling electrical conductivity with constrains on mantle thermo-chemical structure derived from the analysis of seismic data (in the form of P-to-s and S-to-p receiver functions). Further, we explore the links between electrical conductors and lithospheric controls on occurrence of critical mineral deposits.
Diagenetic modelling to evaluate the burial history of exhumed clastic rocks: the case of Tertiary Piedmont Basin (NW Italy)
Authors: Tamburelli Silvia , Di Giulio Andrea
Published: February 2023

The Tertiary Piedmont Basin (TPB) is an Eocene-Pliocene episutural basin sealing the tectonic junction of the Alps and Appenines belts (NW Italy). The burial history of its easternmost part remains unknown since the whole succession has been involved in the Northern Apennines thrust and fold belt during Miocene-Pliocene time and is presently exhumed and truncated on its northern side by the Villalvernia-Varzi tectonic line, which represents a regional crustal-scale strike-slip fault zone, that have accommodated a part of the tectonic deformation in the Alps-Apennines tectonic knot during Oligo-Miocene time.Starting from a thermal history calibrated through apatite fission tracks and microthermometric analyses of fluid inclusions in diagenetic minerals, we investigated the burial history of sediments of that part of the basin using a diagenetic software modelling approach. The rationale of this approach is to study the compaction degree of medium-size clastic rocks (sandstones), and the observed residual intergranular volume (IGV), assumed to be the best proxy for the estimation of burial suffered by clastic rocks in compaction dominated lithified clastic sequences.Based on the regional context, three plausible but different burial histories have been tested and calibrated into the diagenetic modelling software: 1) a minimum burial history assuming no significant additional burial occurred on top of what is presently preserved in the outcrops at the top of the sequence; 2) an intermediate burial history with an hypothetical 400m burial and erosion related to the formations that are presently exposed just on the northern side of Villalvernia-Varzi line (early Miocene shallow marine sandstones); 3) a maximum burial history with 900m of Miocene sediments deposited above the youngest preserved unit (Castagnola Fm.) similarly to what is actually observed in the TPB basin westward.What we can resume from our study is that the burial history that best explains the observed IGV data by the diagenetic modelling is the one with 900m of Miocene sediments originally accumulated on top of presently exposed rocks and then eroded. This result has important regional consequences for the reconstruction of the complex stratigraphic-tectonic evolution of the studied area, and more in general shows that diagenetic modelling has a strong potential for shedding some light on the burial history of exhumed clastic sequences.
Ice nucleation active site-independent stochasticity in heterogeneous ice nucleation
Authors: Lbadaoui-Darvas Mária , Nenes Athanasios , Laaksonen Ari
Published: February 2023

Clouds are central elements of the hydrological cycle and climate. They are responsible for precipitation and strongly impact global and regional temperature by reflecting incoming solar radiation, and absorbing heat emitted from Earth. The amount of ice contained in clouds determines much of their properties and their impact on climate. Cloud ice is mostly formed by heterogeneous nucleation (HIN), catalyzed by insoluble airborne particles (such as dust, biological particles and soot). Despite its importance, the description of HIN in climate models is vastly incomplete and remains one of the major challenges that impedes further progress in estimates of anthropogenic climate change. One important open question is whether HIN should be modelled as a deterministic (time independent) or as a stochastic (time dependent) process. The typical sigmoidal shape of freezing curves - i.e., the fraction of frozen samples as a function of time - suggests the latter to be the correct approach. Current stochastic models cast the entire stochastic behavior on the differences between the IN activity of different ice nucleation active sites (INAS) in the sample. Recent studies however indicate that a large part of stochasticity may be independent from INAS variability. The current work uses large scale molecular simulations freezing droplet ensembles on pure graphitic surfaces to explore the molecular scale origins of INAS independent stochasticity. We find that the interplay of three main factors: the size fluctuations of the pre-critical ice embryo, capillary wave fluctuations of the non-frozen droplet surface and the extent of stacking disorder - i.e.: cubic to hexagonal polymorph ratio - in the frozen droplet manifests as observable stochasticity even if the properties of the IN surface are identical. We conclude by quantifying the extent of INAS-independent stochasticity as a range of contact angles in the framework of the Adsorption Nucleation Theory. The resulting representation is then used to provide a stochastic adsorption-based parameterization of deposition freezing on soot particles. 
Environmental history and geophysical investigation of the Nagy-sziget, Rácalmás, Hungary
Authors: Vitai Ákos , Csernyik Laura , Visnovitz Ferenc , Székely Balázs
Published: February 2023

The interplay of the hydrology of a great river and tectonics in floodplain setting is always a challenging research topic. The evolution of the river course, development of islands, oxbow lakes, changing channel sinuosity can be evaluated as signals of these two processes. In our study area, we seek to explain the evolutionary history of the Nagy-sziget, Rácalmás, Hungary by using a multidisciplinary approach. We integrate field observations, evaluation of historic maps, and results of our own geophysical measurements in order to reconstruct the environmental history of this island of the river Danube. The investigated island is located south of Budapest, in the southern corner of Csepel Island, where the Soroksári-Danube branch joins the main branch. The area is particularly interesting in geodynamic sense, as the region is crossed by the Mid-Hungarian Mobile Belt at the confluence of the Ráckeve (Soroksári) Danube branch close to the northern part of the island. During the field campaign we observed characteristic micro relief structures in the field that have been integrated with landforms indicated on historical maps. Furthermore, we wanted to know how these topographical patterns continue below the surface, therefore geoelectric measurements were carried out. We conclude that the area of the island started to grow very rapidly after the river regulations. Our geoelectrical tomography and electromagnetic measurements showed that, despite the very low relief, the subsurface geology is reflected in microtopography. Based on these results various scenarios for the formation of the island have been put forward; a final scenario will emerge from our planned measurements. We concluded that the evolution of the Nagy-sziget may have had tectonic, landsliding, sedimentary and flood-related components, which are specific to different regions. With the integrated results of the geoelectric and electromagnetic measurements and the study of historical maps, we managed to reconstruct the growth of the island in unprecedented detail over the past 250 years and we can formulate some implications to a certain extent for periods before written documents.
Moment vs local magnitude scaling of small-to-moderate earthquakes from seismic moment estimation of 10 years (2009-2018) of Italian seismicity
Authors: Supino Mariano , Chiaraluce Lauro , Di Stefano Raffaele , Castello Barbara , Michele Maddalena
Published: February 2023

We computed moment (Mw) and local magnitude (ML) of about 250,000 earthquakes occurred in Italy from 2009 to 2018 and recorded at seismic stations of the Italian National Network managed by INGV.For moment magnitude computation, we start from raw velocity waveforms and invert the displacement spectra of more than 2,000,000 S-waves manually picked. We use the probabilistic method of Supino et al. [2019] to estimate the a-posteriori joint probability density function of the source parameters: seismic moment M0, corner frequency fc and high-frequency decay γ. Mw is obtained from M0 using the Kanamori [1977] equation.We start from the same waveforms to compute local magnitude using two designed on purpose codes, PyAmp and PyML [Di Stefano et al., 2023], and an attenuation law specific for the Italian region, Di Bona et al. [2016], obtaining ML values characterized by quality and homogeneity.Both magnitude catalogs can be reproduced due to the availability in open databases of all the input and output parameters used for processing.We observe a self-similar scaling between fc and M0 for Mw larger than ~2.0. For smaller magnitudes, S-wave spectra show an almost constant corner frequency (~10 Hz), which does not scale with the earthquake source (seismic moment). We interpret this as the constant cut-off frequency of the anelastic attenuation, which acts as a low-pass filter and produces an apparent corner frequency. The latter is lower than expected, and corresponds to an apparent larger source duration.Because of the conservation of total displacement integral after a low-pass filtering, signals must exhibit a maximum amplitude lower than expected to “compensate” the apparent larger source duration. ML values are therefore expected to be underestimated while moment magnitudes, by definition, are not affected by this as they are proportional to the displacement integral.Coherently, the comparison of our Mw and ML estimates shows the systematic underestimation of ML with respect to Mw for small magnitude events. The deviation from a 1:1 scaling relationship between ML and Mw overlaps the magnitude range where the constant apparent corner frequency arises in the M0-fc scaling (ML <~ 2).Regarding the upcoming of a new generation of earthquake catalogs characterized by very low completeness magnitudes (MC << 2), our results suggest that a robust analysis of the statistical features of these catalogs (e.g., event size distribution) should consider the use of a precise magnitude estimate such as Mw instead of ML.
Parametrization of temporal emission variability for greenhouse gases and air pollutants
Authors: Jaekel Ilona , Banzhaf Sabine , Chan Edward , Kranenburg Richard , Dellaert Stijn , Schaap Martijn
Published: February 2023

The basis for modelling greenhouse gases and air pollutants is an explicit spatially and temporally resolved specification of the anthropogenic emissions. Although a lot effort has been put in to improve the spatial allocation for emission inventories, the temporal variability for many sectors is not aligned with real-world conditions and often prescribed using static or constant time profiles. We have been developing a modelling system to predict the spatial-temporal behaviour of anthropogenic emissions of air pollutants and greenhouse gases in which we aim to also include the influence of e.g. meteorological conditions on activities and emission factors. As such, we are replacing the static emission profiles with parametrizations one by one. Here, we present the approaches we are taking for 3 sectors. First, for large power plants the point source metadata of the CAMS-REG inventory have been matched to those from the ENTSO-E database to link the hourly production statistics to the emission inventory. Next, we tried to group the production time series of the different kinds of power plants, but this turned out not to be possible as they show very specific profiles. It was affordable to include for each power plant its individual emission time profile into the emission model. Second, for small stationary combustion the temporal variability is calculated for two building types, i.e. office and residential buildings, using the heating degree day method for oil and gas. For residential wood and coal combustion additional constraints with respect to heating behaviour have been applied. Third, for methane emissions from landfills we based our parametrization on investigations showing a significant pressure dependency of the emission flux. The original (constant) emission profile is exchanged with a profile which is spatially and temporally dependent on the change of atmospheric pressure, which leads to a variability of a factor 4 around the annual mean flux. Given the impact of synoptic variability the behaviour shows comparable patterns across large regions. At the meeting we will also show our planned approach to detail the emission variability of methane and PM from the agricultural sector (enteric fermentation, livestock housing and land management).
Baltic raised bog carbon dioxide balance dynamics and its biophysical determinants - Kusowo case study
Authors: Poczta Patryk , Harenda Kamila , Lamentowicz Mariusz , Chojnicki Bogdan
Published: February 2023

Peatlands are ecosystems with relatively low net productivity but a long-term carbon storage period (thousands of years). This carbon stock is continuously related to its hydrogenic origin, resulting in the high sensitivity of peatlands to hygrothermal factors such as temperature and precipitation. Changing the balance of temperature and wetness in peatlands may stimulate higher ecosystem respiration and/or reduce the photosynthetic capacity of plants and consequently shift the peatland from net sinks to sources of CO2 to the atmosphere. Thus, the peatland-climate interaction study is crucial for understanding and predicting their faith in the future.Since July 2019, the eddy covariance (EC) technique has been used to monitor CO2/H2O net fluxes at a baltic raised bog in Bagno Kusowo Nature Reserve, northern Poland (53.82 N, 16.59 E, 144 m a.s.l.). This peatland started formatting thousands of years ago and currently reaches up to 8 m of peat depth. The measurement tower works in collocation with the meteorological station, thus the standard meteorological parameters are measured along with flux observations. These common measurements were the basis for estimating peatland carbon dioxide balance and its relation to biophysical factors.An early start of vegetation (March-April) on the baltic raised bog was noted, as well as predominant emissions from the peatland in mid-summer (August). During 2.5 years of measurements, the peatland in Kusowo was both a net sink and a source of CO2 on an annual basis. The negative impact of lowering the water table level on the CO2 balance (higher emissions) is more noticeable during the growing season when higher temperatures intensify the respiration processes.
Influence of Disturbance on Sedimentary Carbon Stocks in a Temperate Seabed
Authors: Muir Hannah , Keenan Jacqui , Henthorn Rowan , Strong James , Reading David G. , Duncan Peter , Skov Martin W. , Hiddink Jan G. , Unsworth Richard K. F. , Warwick Phillip E. , Evans Claire
Published: February 2023

Shelf sea sediments are natural, long-term carbon sinks that may be managed for Blue Carbon (BC) storage to offset greenhouse gas emissions and contribute to nations ‘Net Zero’ ambitions. The Isle of Man in the Irish Sea has territorial waters equivalent to approximately 85% of its total jurisdiction, and significant potential for BC offsetting through seabed management. The Island’s Government is developing a comprehensive BC management plan to maximise carbon sequestration and restore seabed biodiversity and wider ecosystem services. We determined the effects of disturbance on sedimentary carbon stocks and accumulation rates in the western territorial sea, a region of mud-dominated sediment with elevated disturbance from Nephrops norvegicus bioturbation and bottom-contact fishing activities. Sediment cores were collected from approximately 5 to 12 nautical miles off the west coast of the Isle of Man, at depths from 60 m to 120 m. The cores were sectioned and analysed using: elemental analysis and isotope ratio mass spectrometry to quantify organic and inorganic carbon stocks; and gamma-ray spectrometry and alpha spectrometry to identify and quantify radionuclides of Cs-137, Pb-210, Am-241 and Po-210 to determine sedimentation rates. Complete sediment cores were scanned using X-ray to generate radiographs and laminographs, to determine internal core structure and identify N. norvegicus burrows. The results show that organic/inorganic carbon and sedimentation rates in offshore sediments vary over time and space. Analysis is ongoing to ascertain if these variations are related to disturbance of the sedimentary system, using indicators of fishing intensities and N. norvegicus bioturbation. Results of this analysis will be presented to elucidate the effects of disturbance on sedimentary carbon stocks and accumulation.
Simulating worst case heatwaves during the Paris 2024 Olympics
Authors: Yiou Pascal , Cadiou Camille , Faranda Davide , Jézéquel Aglaé , Malhomme Nemo , Miloshevich George , Noyelle Robin , Pons Flavio , Robin Yoann , Vrac Mathieu
Published: February 2023

The Summer Olympic Games in 2024 will take place during the apex of the temperature seasonal cycle in the Paris Area. The midlatitudes of the Northern hemisphere have witnessed a few intense heatwaves since the 2003 epitome event. Those heatwaves have had environmental and health impacts, which often came as surprises. In this paper, we search for the most extreme heatwaves in Ile-de-France that are physically plausible, under climate change scenarios, for the decades around 2024. We apply a rare event algorithm on CMIP6 data to evaluate the range of such extremes. We find that the 2003 record can be exceeded by more than 4°C in Ile-de-France before 2050, with a combination of prevailing anticyclonic conditions and cut-off lows. This study intends to build awareness on those unprecedented events, against which our societies are ill-prepared. Those results could be extended to other areas of the world.
Influence of atmospheric rivers, cyclones and fronts on precipitation in the Arctic – a climatological perspective
Authors: Lauer Melanie , Rinke Annette , Gorodetskaya Irina , Sprenger Michael , Mech Mario , Crewell Susanne
Published: February 2023

The enhanced warming in the Arctic compared to the global mean – a phenomenon called Arctic Amplification - has different effects, including impacts on the hydrological cycle and thus the precipitation. In the Arctic, there are two major sources of moisture leading to increased precipitation formation: The enhanced local evaporation due to the missing insulation due to reduced sea-ice cover and the increased poleward moisture transport which is often associated with atmospheric rivers (ARs).Previous studies have shown that ARs are a significant source for rain and snow in the Arctic. ARs are dynamically linked to the extratropical cyclones and fronts. Thus, AR-related precipitation can be not only concentrated within the AR itself, but also occur within the cyclone and frontal boundaries. Therefore, we developed a new method to distinguish precipitation within the AR shape and the precipitation related to cyclones and fronts based on ERA5 reanalysis. Thereby, we estimate how much precipitation occurs within AR, cyclone and frontal boundaries, separately and overlapping together. We applied this method for different case studies during two campaigns performed at and around Svalbard within the Collaborative Research Center “Arctic Amplification: Climate Relevant Atmospheric Surface Processes, and Feedback Mechanisms (AC)3”. Differences in the contributions of ARs, cyclones and fronts to the total precipitation could be identified comparing the both campaigns. During the early summer campaign (ACLOUD), precipitation (both rain and snow) was more confined within the AR shapes, especially in the area in which the AR is connected to fronts. In contrast, during the early spring campaign (AFLUX), precipitation (predominantly snow) was more restricted to the cyclone regions without connection to ARs and fronts. Generally, a higher precipitation intensity was found within ARs, especially when they are connected with cyclones and fronts.In a climatological perspective, we apply this method to the ERA5 reanalysis data (1979 - 2020) to quantify the occurrence and influence of ARs and related cyclones and fronts. For this extended analysis, we consider the whole Arctic. This allows us to analyse the change of precipitation (in terms of type and frequency) related to the different weather systems during the last four decades. Furthermore, we can assess seasonal differences. In summary, we can investigate in which regions ARs, cyclones and fronts have a greater impact and if and how it also depends on different surface types (sea ice, open ocean, and land).This work is supported by the DFG funded Transregioproject TR 172 “Arctic Amplification (AC)3“.
Jupiter and Saturn normal modes observed through Juno and Cassini gravity measurements
Authors: Durante Daniele , Guillot Tristan , Iess Luciano , Stevenson David , Mankovich Christopher , Markham Steve , Racioppa Paolo , Spilker Linda , Bolton Scott
Published: February 2023

Recently, the Juno and Cassini spacecraft shed light on the interior of both Jupiter and Saturn, the two gas giants of the Solar System. Juno is currently orbiting Jupiter in a highly elliptical 53.5-day orbit, with a perijove altitude of about 4000 km. After the 33rd passage in April 2021 (labeled PJ33), the mission ended its nominal mission and entered its extended mission. On the contrary, the Cassini spacecraft ended its mission on September 15th, 2017 with a deliberate plunge into Saturn’s atmosphere. In its final phase, the Grand Finale, Cassini provided insights on Saturn’s rings, atmosphere, and interior. Out of the 22 proximal orbits, six pericenter passes have been devoted to the determination of the gravity field of the planet.The gravity science experiments on board Juno and Cassini precisely measured, respectively, Jupiter and Saturn zonal gravitational fields. The measured gravity harmonics have been used to constrain the interior structure and atmospheric zonal flow on both planets.The Cassini data analysis have shown the need to include unknown accelerations to properly fit the data to the expected noise (Iess, 2019). Similar unexplained accelerations have been observed also on Juno gravity data (Durante, 2020). Since Jupiter and Saturn are gas giants, unconventional phenomena can be at play, including normal modes, non-zonal atmospheric dynamics, or flows in the dynamo region.The analysis of the accelerations acting on Cassini provided evidence for p-modes on the planet (Markham, 2020), while the analysis of Juno gravity data revealed p-modes on Jupiter and provided upper bounds on lower frequency f-modes. Here, we show the results for normal modes on both Jupiter and Saturn obtained with the analysis of gravity data of both Juno and Cassini.
Variabilities of inorganic nitrogen in airborne particulate matter in Busan, South Korea
Authors: Lee Seon-Eun , Park Geun-Ha
Published: February 2023

The atmospheric deposition of anthropogenic nitrogen is an increasingly important new source of nitrogen (N) in the ocean. This study examines the variabilities of the atmospheric inorganic reactive nitrogen species in airborne particulate matter, based on the two-year sample collection of total suspended particles (TSP) in Busan, South Korea adjacent to the Korea Strait (KS) from March 2019 to February 2021. Concentrations of nitrate (NO3-), ammonium (NH4+), and non-sea-salt sulfate (nss-SO42-) ions contained in the TSP significantly declined by ~9, ~25, and ~24 %, respectively, between the two years. The seasonally clustered backward trajectories have shown significant decreases in those ionic concentrations from the Asian outflow, primarily owing to the reduced human activities after the COVID-19 pandemic outbreak. The atmospheric deposition of the inorganic N species (i.e. NO3- and NH4+) may contribute ~0.78 % and ~2.6 % to the annual mean oceanic net primary production (NPP) and the new production, respectively, in a 2° latitude × 2° longitude domain in the KS. Given the expected wet and organic N deposition, the atmospheric total N deposition could account for ~2.1 % and ~7 % of the annual mean NPP and the new production in the KS, respectively.
"Methane oxidation in the Estuary of a medium-sized European river, the Scheldt"
Authors: Delre Annalisa , de Groot Tim , Röckmann Thomas , Engelmann Julia , Reichart Gert-Jan , Niemann Helge
Published: February 2023

Coastal systems including river deltas are the major sources of methane from the ocean to the atmosphere; however, large uncertainties exist on the actual source strength. Abiotic and biotic factors controlling methanogenesis, methanotrophy and methane efflux to the atmosphere thus need better understanding. In this presentation, we will show data from a recent cruise along the Sheldt Estuary from Antwerp (salinity: 2 psu) towards the open North Sea (salinity: 31 psu). Methane concentrations were elevated in Antwerp with up to 110 nM, decreased downriver to values ~50nM, increased to 180 nM at the inflow of a large canal (Ghent–Terneuzen Canal) and then decreased to ~70nM in the open North Sea. Methane oxidation rates were highest in the city of Atnwerp (~29 nM/d), only slightly elevated at the inlet of the Ghent–Terneuzen Canal (~10 nM/d) and lower in the open North Sea (5nM/d). Differently to previous findings in other river systems, we could not find a clear dependency of methane oxidation to salinity. In this presentation, we will also present data on CH4 fluxes from the river to the atmosphere, CH4 stable isotope systematics and the composition of the methanotrophic community to further constrain methane dynamics in the estuary.
Can earthquakes nucleate on nominally stable velocity-strengthening faults?
Authors: Dal Zilio Luca , Selvadurai Paul A. , Ampuero Jean-Paul , Tinti Elisa , Cocco Massimo , Cappa Frédéric , Wiemer Stefan , Giardini Domenico , Team the Bedretto
Published: February 2023

Tectonic faults are often assumed to slip either slow due to stable, velocity-strengthening frictional behavior, or fast as a result of velocity-weakening friction leading to dynamic (seismic) rupture. As a consequence, velocity-strengthening faults may be regarded as intrinsically stable as they do not spontaneously nucleate seismic events. However, recent laboratory and in-situ experiments of fluid injection challenged such assumptions. Here we present a fully coupled hydro-mechanical fault model in which stable, rate-strengthening frictional behavior is combined with dynamic weakening due to rapid poroelastic effects, allowing unstable (seismic) slip to occur on nominally stable faults. In our numerical experiments, fluid injection reduces the effective normal stress and frictional resistance, thus bringing the fault to failure. The onset of fault failure is controlled by competing mechanisms of shear-induced dilation and shear-enhanced compaction, which cause fault weakening and the propagation of a slow-slip transient from the fluid injection point. When a critical size of the slow slip patch is reached, dynamic rupture eventually nucleates at the slow-slip event front and propagates beyond the fluid pressure perturbed region. Further numerical experiments indicate that, when the fault is critically stressed, the growth of the aseismic patch – prior to dynamic rupture – occurs in a few seconds, whereas at lower stress levels, the aseismic slip phase propagates slowly over hundreds of seconds. These results predict that poroelastic compaction and fluid pressurization can cause the transition from aseismic slow-slip to fast seismic slip and the propagation of dynamic rupture on velocity-strengthening faults. In particular, they demonstrate that compaction-induced fluid pressurization can overcome the initial phase of shear-induced dilatancy, thus allowing the propagation of dynamic rupture in the form of pulse-like pore-pressure waves. The implication that earthquake rupture may nucleate on rate-strengthening faults, presently considered to be nominally stable, requires a re-evaluation of seismic hazard in many areas, particularly in the case of fluid injection in enhanced geothermal systems and CO2 storage.
Extreme waves induced by localized frequency and amplitude modulations in a random sea: an experimental study
Authors: He Yuchen , Trillo Stefano , Chabchoub Amin , Witt Andy , Hoffmann Norbert
Published: February 2023

It is known that the modulation instability (MI) is a focusing mechanism responsible for the formation of rogue waves (RWs). Such dynamics are initiated from the injection of sidebands, which translates into an amplitude modulation (AM) of the wave field. The nonlinear stage of unstable wave evolution can be described by exact breather solutions of the nonlinear Schrödinger equation (NLSE). In fact, the amplitude modulation of such coherent RW structures is connected to a particular phase-shift seeded in the carrier wave, i.e. a particular form of localized frequency modulation (FM). By seeding only the local FM information of a deterministic breather to a regular wave train, our experiments show that such an FM localization can indeed trigger pure breather-type RW dynamics. Results of an experimental study on identifying spontaneous RWs in a random wave field by isolating the respective FM and AM dynamics will also be discussed. 
Taking a closer look: How spectromicroscopic imaging of organo-mineral associations leads to a novel perspective on interrelated soil functions
Authors: Schweizer Steffen
Published: February 2023

A wide range of image-based techniques revealed mounting evidence of a heterogeneous arrangement of mineral-associated organic matter (OM) in soils at the microscale and nanoscale. Spectromicroscopic approaches using such as NanoSIMS, STXM-NEXAFS, AFM, STEM-EELS, and others have provided insights about a patchy and piled-up arrangement of OM. This arrangement is determined by different local OM properties and mineral composition as well as OM-OM interactions. The emerging conceptual framework of the microscale arrangement of OM affects our understanding of soil functions: By compartmentalizing and decoupling local carbon sequestration in the mineral soil matrix, by localizing the mechanical stabilization of soil structure, by altering surface properties and re-distributing ion exchange sites, and by shaping distinct biotic microenvironments. After an overview on the spectromicroscopic evidence, this contribution will illustrate the emerging conceptual framework of localized soil functions, and highlight opportunities for research approaches based on the patchy and piled-up arrangement of OM at the microscale and nanoscale.
Calibrations of Surface Air Temperature Forecasts at Short- and Long-term Timescales Based on Statistical Pattern Projection Methods
Authors: Zhu Shoupeng , Lyu Yang , Zhi Xiefei
Published: February 2023

So far, plenty of efforts have been pursued on the numerical weather prediction (NWP). However, systematic errors could never be ignored in the output applications. To supply the numerical forecasts with higher accuracies, statistical postprocessing is often expected to correct systemic biases and has been one of the key components of the forecasting suites. Based on the NWP models and taking advantages of the raw stepwise pattern projection method (SPPM), the neighborhood pattern projection method (NPPM) is newly proposed to postprocess the model outputs and to improve forecast skills of daily maximum and minimum temperatures (Tmax and Tmin) over East Asia for short-term timescales, as well as the Kalman filter based pattern projection method (KFPPM) for longer-term forecasts. For the short-term lead times of 1–7 days, the SPPM is slightly inferior to the benchmark of decaying averaging method, while its insufficiency decreases with increasing lead times. The NPPM shows manifest superiority for all lead times, with the mean absolute errors of Tmax and Tmin decreased by ~0.7° and ~0.9°C, respectively. Advantages of the SPPM and NPPM are both mainly concentrated on the high-altitude areas such as the Tibetan Plateau, where the raw model outputs show the most conspicuous biases. As for longer-term forecasts at the subseasonal timescale, the NPPM effectively calibrates the temperature forecasts at the early stage. However, with the growing lead times, it shows speedily decreasing skills and can no longer produce positive adjustments over the areas outside the plateaus. By contrast, the KFPPM consistently outperforms the other calibrations and reduces the forecast errors by almost 1.0°C and 0.5°C for Tmax and Tmin, respectively, both retaining superiorities to the random climatology benchmark till the lead time of 24 days. The optimization of KFPPM maintains throughout the whole range of the subseasonal timescale, showing most conspicuous improvements distributed over the Tibetan Plateau and its surroundings. Case experiments further demonstrate the above-mentioned features and imply the potential capability of the NPPM and KFPPM in improving forecast skills and disaster preventions for extreme temperature events. Besides, compared with the initial SPPM, they not only produces more powerful forecast calibrations, but also provides more pragmatic calculations and greater potential economic benefits in practical applications.
A deep learning approach based on Bayesian optimization for prediction of stable isotope concentrations in stream and groundwater
Authors: Sahraei Amir , Houska Tobias , Breuer Lutz
Published: February 2023

High temporal resolution (i.e., sub-daily) stable isotope concentrations of multiple stream and groundwater sources reveal small-scale, rapid transport and mixing processes that are not discernible at coarser resolution. However, long-term, routine sampling of multiple water sources at high temporal resolution is far from widespread. In recent years, the rise of deep learning offers the opportunity to further improve the prediction accuracy of infrequently measured data owing to its capability to efficiently abstract interrelationship patterns in complex and non-linear systems. In this research, we explore the potential of a Long Short-Term Memory (LSTM) deep learning model to predict high-resolution (3 h) isotope concentrations of multiple stream and groundwater sources in the Schwingbach Environmental Observatory (SEO), Germany. The key objective of this study is to examine the predictive performance of the LSTM that is simultaneously trained on multiple sites with a set of explanatory data that are more convenient and less expensive to collect in comparison to the stable water isotopes. The explanatory data comprise meteorological data, soil moisture, and natural tracers (i.e., water temperature, pH, and electrical conductivity). A sensitivity analysis is applied to investigate the model performance under different input data and sequence lengths. A Bayesian optimization algorithm is employed to optimize the hyperparameters of the LSTM to ensure an efficient model performance. The main outcome of our study shows that the LSTM enables the prediction of stable isotopes in streams and groundwater by using only a short sequence (6 hours) of recorded water temperature, pH, and electrical conductivity. The best performing LSTM reached on average an RMSE of 0.7‰, MAE of 0.4‰, R2 of 0.9, and NSE of 0.7. The proposed model can be used to predict continuous time series of stable water isotope concentrations, either for gap filling or in cases when continuous data collection is not possible. This is very worthwhile in practice since measurements of tracers used in our LSTM are still much cheaper than those of stable water isotopes and can be carried out continuously with relatively low associated maintenance. In future research, the pre-trained LSTM should be applied through transfer learning to other catchments at which the length and resolution of available data are not sufficient to build a standalone model.
Evaluation of surface and groundwater quality and identification of saltwater sources by hydrogeochemical analysis in river Neretva coastal aquifer system
Authors: Lovrinovic Ivan , Aljinovic Iva , Srzic Veljko
Published: February 2023

The river Neretva coastal aquifer system is the largest agricultural area along Croatia's Adriatic Sea coast. With the construction of an embankment, pumping stations, and melioration channels, a once-marshy area has been transformed into an area with favourable agricultural conditions.  Due to its proximity to the sea, numerous anthropogenic impacts in the region, and climate change, groundwater and surface water in the study area are presently significantly influenced by the salinization process. Multiple times per year, groundwater and surface water samples are collected to fully comprehend saltwater processes and the origin of saltwater in the study area. Within each sample, the concentration of major ions (K+, Na+, Ca+, Mg2+, Cl-, HCO3- and SO42-) is determined under laboratory conditions.The analysis of major ions indicates that seawater intrusion is the primary source of salinization in both unconfined and confined aquifers. In contrast to unconfined aquifer, confined aquifer is minimally affected by precipitation and surface water regimes. In addition, samples of groundwater from unconfined aquifer are categorized into three groups based on their degree of contamination with seawater. The samples from the Diga area that are closest to the Adriatic Sea are most significantly influenced by the seawater. The groundwater quality in the Jasenska area varied significantly between dry and rain periods, whereas groundwater samples from the area of Vidrice revealed the lowest level of seawater contamination.   Neretva river surface water samples reveal the presence of a salt wedge, while river Mala Neretva samples indicate that river Mala Neretva is the primary source of freshwater in the study area during dry season.
Spatially distributed analysis of heavy metal pollution in the upper catchment of the river Oker, Germany
Authors: Wagner Paul , Rosado Daniel , Rincón Vanessa , Fohrer Nicola
Published: February 2023

Heavy metals are still found in the rivers of the Harz Mountains in Germany as a result of mining. In the EXDIMUM research project (Extreme Weather Management with Digital Multiscale Methods) a spatially distributed measurement campaign was carried out in the catchment of the river Oker upstream of the gauge at Schladen. The focus was on the rivers Gose and Abzucht upstream of the city of Goslar. The objectives of this research were to quantify the deposition of heavy metals in the sediment and to identify source areas of heavy metal pollution in the catchment. To this end, sediment samples were taken from the river bed of the main and tributary rivers upstream of each confluence, so that it was possible to determine from which sub-catchments heavy metals entered the main channel. The sediment samples were analyzed for various heavy metals in the environmental laboratory of the Christian-Albrechts-Universität zu Kiel using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Total content of lead and zinc were above reference values like the threshold effect concentrations (TEC) and the probable effect concentrations (PEC) and the effects range-low (ERL) and the effects range-median (ERM) in several sediments. The spatial analysis shows that elevated levels of contamination occur particularly in the vicinity of former mine pits, smelter sites, and mine dumps. Within the EXDIMUM project, further campaign measurements during and after a flood event are planned, which, together with the modeling of runoff and sediment discharge in the study area, should allow to draw conclusions on the potential influence of extreme events on the export of heavy metals.
Ongoing development of a three-dimensional sedimenttransport model for local scour study
Authors: Renaud Matthias , Chauchat Julien , Bonamy Cyrille , Bertrand Olivier
Published: February 2023

Erosion due to scouring processes around hydraulic structures is a major topic in hydraulic engineering. Despite more than a centuryof active research, its accurate prediction remains poor and its numerical modelling is still a major challenge for civil engineers.Different studies have particularly identified scouring phenomenon as a major cause for bridge failures making its forecasting ofoutermost importance to assess bridge safety and resiliency to extreme events. Numerical prediction of scour around an obstaclerequires the accurate simulation of the complex turbulent fluid flow in the vicinity of the structure as well as its interactions withthe surrounding sediment and the bed morphology. This involves a wide variety of processes such as bed-load transport, turbulentsuspension and gravity-driven avalanches. The classical morphodynamics models used in the industry, although adapted to studysediment transport at large scales, often fail to accurately simulate the scour process as well as the flow around hydraulic structures.A detailed comparison of the flow hydrodynamics around a wall-mounted cylinder using TELEMAC-3D and OpenFOAM will bepresented. Furthermore, scour processes concern a wide range of structures with complex geometries that geophysical numericalmodels are not able to consider e.g. vertical non-emerging structures or structures with pressurized flows. Other models betterreproduce the local physical processes such as SedFoam, based on a two fluid approach where the sediment is modeled as a continuum.Unfortunately, the computational cost of such a model remain to high for engineering purposes. Those considerations emphasize theneed for an intermediate-scale model, able to solve the different turbulent flow structures associated with scouring at an affordable cost.The development of such a model is the main objective of the present study and as first step, idealized benchmarks on sedimentation,turbulent suspension and dune migration will be presented. In the future, ongoing work using SedFoam will be used to develop newclosures, that will be tested in the present model, which will be made open source.This thesis work is carried out within the framework of the Oxalia Hydraulics Chair of the Grenoble INP Foundation.
Identifying hydrological regularities via perceptual models at the regional scale
Authors: Fenicia Fabrizio , McDonnell Jeffrey J.
Published: February 2023

Identifying hydrological regularities, such as patterns and laws that explain the observed variability in catchment response, is an important objective of catchment hydrology. These insights could contribute regional knowledge that can be exploited in catchment classification studies and improve model realism and parsimony. But how to infer such regularities, and to what extent are they generalizable, in view of the evidence of uniqueness of place? In this presentation, we propose the development of a regional scale perceptual model as a framework to stimulate the search of hydrological regularities and to represent them visually. Our approach is intended for nested catchments, a scale that we consider is sufficiently large to provide an interesting contrast in hydrological responses, but sufficiently small to encompass local dominant process that may be different elsewhere. Our perceptual model development approach is demonstrated in the 27,000 km2 Moselle catchment, using streamflow data at 26 nested subcatchments, and commonly available data of landscape properties, including topography, vegetation, geology and soil. The identified signatures of streamflow spatial variability highlighted the role of precipitation, geology and topography, which affected, respectively the average flows, base runoff and lag time. Soil and vegetation, on the other hand, were not found to be a dominant cause of hydrograph variability, which might appear surprising, considering that soil properties are one of the key ingredients of many distributed models. The framework undertaken in this study may be useful to develop perceptual models in other basins at regional scale, and to map and regularize the variety of dominant hydrological processes.