bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal forecasting of Alpine snow depth: evaluation of a climate service prototype
Authors: Terzago Silvia , Bongiovanni Giulio , von Hardenberg Jost
Published: March 2022

Mountain glacier shrinking, seasonal snow cover reduction and changes in the amount and seasonality of meltwater runoff are already affecting water availability for both local and downstream uses. Water is needed by different competing sectors including drinking water supply, energy production, agriculture, tourism, and extremely dry seasons can lead to economic losses. Reducing potential impacts of changes in water availability involves multiple time scales, from the decadal time scale for the realization of water management infrastructures to the seasonal scale, to plan the use of water resources and allocate them with some lead time.

In the framework of the MEDSCOPE ERA4CS project we focused on the seasonal time scale and we developed a climate service prototype to estimate the temporal evolution of snow depth and snow water equivalent with up to 7 months lead time. Forecasts are initialized on November 1st and run up to May 31st of the following year. The prototype has been co-designed with and tailored to the needs of water and hydropower plant managers and of mountain ski resorts managers. 

We present the modelling chain, based on the seasonal forecasts of ECMWF and Météo-France seasonal prediction systems, made available through the Copernicus Climate Change Service (C3S). Seasonal forecasts of precipitation, near-surface air temperature, radiative fluxes, wind and humidity are bias-corrected and downscaled to three high elevation sites in the North-Western Italian Alps, and finally used as input for a physically-based multi-layer snow model (SNOWPACK). The RainFARM stochastic downscaling procedure adapted for mountain regions is used for downscaling precipitation data, and stochastic realizations are employed to estimate the uncertainty due to the downscaling method.

The skill of the prototype in predicting the monthly snow depth evolution from November to May in each season of the hindcast period 1995-2015 is demonstrated using station observations as a reference. We show the correlation between forecasted and observed snow depth and we quantify the forecast quality in terms of reliability, resolution, discrimination and sharpness using a set of probabilistic measures (Brier Skill Score, Area Under the ROC Curve Skill Score and Continuous Ranked Probability Skill Score). We finally discuss implications of the forecast quality at different lead times as well as the added value of bias-correction and downscaling of precipitation data on snow depth forecasts. Real-time snow forecasts for the current season (2021-2022) and for earlier ones are available at this link: http://wilma.to.isac.cnr.it/diss/snowpack/snowseas-eng.html
On the implications of ionospheric disturbances for GNSS precise positioning: a case study of Greenland
Authors: Paziewski Jacek , Jin Yaqi , Miloch Wojciech J. , Sieradzki Rafal , Jarmolowski Wojciech , Hernandez-Pajares Manuel , Wielgosz Pawel , Berdermann Jens , Hoque Mainul , Høeg Per , Garcıa-Rigo Alberto , Lyu Haixia , Milanowska Beata , Clausen Lasse B. N. , Monte-Moreno Enric , Orús-Pérez Raul
Published: March 2022

Ionospheric irregularities impair GNSS signals and, in turn, affect the performance of GNSS positioning. Such effects are especially evident for the high latitudes, which are currently gaining the attention of research and industry branches. These activities should be supported with reliable positioning and navigation services. Such needs motivate us to assess, for the first time, the impact of ionospheric irregularities on GNSS positioning performance in Greenland. We fill the gap and evaluate the performance of positioning methods that were not investigated comprehensively until now but meet the demands of a wide range of users. In this regard, we address the needs of mass-market users that most frequently employ single-frequency receivers and expect a meter to submeter-level accuracy in an absolute mode; and the users who require the highest precision solution based on geodetic-grade dual-frequency receivers. We take advantage of the datasets collected at the GNET permanent network in Greenland during three ionospheric storms, namely the St. Patrick storm of March 17, 2015, June 22, 2015, and August 25–­26, 2018. We discover a significant impact of the ionospheric disturbances on the ambiguity resolution performance and the accuracy of the float solution in RTK positioning. Next, assessing the single-frequency ionospheric-free PPP, we demonstrate that the model is generally unaffected by the ionospheric disturbances. Hence, the model is predestined for the application by the users of single-frequency receivers in the areas of frequent ionospheric disturbances. Finally, based on the observation analyses, we revealed that phase signals on the L2 frequency band are more prone to the cycle slips induced by ionospheric irregularities than those transmitted on the first one.
MEGLIO: an experiment to record seismic waves on a commercial fiber optic cable through interferometry measures with an ultra stable laser.
Authors: Herrero Andre , Calonico Davide , Piccolo Francesco , Carpentieri Francesco , Govoni Aladino , Margheriti Lucia , Vassallo Maurizio , di Giovambattista Rita , Stramondo Salvatore , Clivati Cecilia , Concas Roberto , Donadello Simone , Priuli Fabio Simone , Orio Filippo , Romualdi Andrea
Published: March 2022

The experiment MEGLIO follows the seminal work of Marra et al. (2018) where the authors demonstrate the possibility to observe seismic waves on fiber optic cables over large distances. The measure was based on an interferometric technique using an ultra stable laser. In theory, this active measurement technique is compatible with a commercial operation on a fiber, i.e. the fiber does not need to be dark. In 2019, Open Fiber, the largest optic fiber infrastructure provider in Italy, has decided to test this new technology on its own commercial network on land.

A team of experts in the different fields has been gathered to achieve this goal : besides Open Fiber, Metallurgica Bresciana; INRiM, which initially developed the technique, for their expertise on laser and sensors; Bain & Company for the analysis and the processing of the data; INGV for the expertise in the seismology field and for the validation of the observations.

The first year has been dedicated to developing the sensors. In the meantime, a buried optic cable has been chosen in function of its length and the seismicity nearby. The best candidate was the fiber connecting the towns of Ascoli Piceno (Marche, Italy) and Teramo (Abruzzo, Italy) for a length of around 30 km. Although  this technique allows using cable lengths larger than 5.000 km, for this first test we have decided to keep the length short. Actually the cable is mainly buried underneath a road with medium traffic, passes across different bridges and viaducts, starts in the middle of a town and loops in the middle of another town. Thus we expected a strong anthropic noise on the data.

The measurement on the field started in mid June 2020 and the system was operational in early July. We also installed a seismic station at one end of the cable. During these first six months, we have compared the observations on the fiber with the Italian national seismic catalog and the worldwide catalog for the major events. We consider the first results a success. We have detected so far nearly all the seismic activity with magnitude larger than 2.5 for epicentral distance lesser than 50 km. Moreover, we have recorded large events in Mediterranean region and teleseisms. Finally we have recorded new and interesting noise signals. Collecting additional events will be helpful for a better characterization of the technique, its performances and for a statistical analysis.
Hydro-mechano-chemical coupling in rock failure
Authors: Pluymakers Anne , Veltmeijer Aukje , Naderloo Milad , Kortram Jon-Danilo , Barnhoorn Auke
Published: March 2022

Understanding rock failure is key for the safe and efficient development of the subsurface. Gas storage (CO2, H2 or CH4), production of geothermal energy and the traditional extraction of hydrocarbons means fluid injection or extraction. These processes change the local stress state, but also local temperature or chemistry. Such use of the subsurface is about either keeping fluid where it is (storage) or making sure fluids come out with a sufficient but still safe rate. Since fault rocks are in many cases important fluid transport pathways, this needs a careful and complete understanding of how rocks fail. Therefore, a thorough understanding of the stages of deformation leading to failure is key, as well as any potential differences for different rock types and failure modes. We performed uniaxial compressive and triaxial experiments on limestone and sandstone to investigate the hydro-mechano-chemical coupling in rock failure, using active and passive acoustics to monitor the failure behaviour. All experiments are done at room temperature.

Using active acoustics for first arrival times is an established technique. We use here the more novel coda-wave interferometry technique to track deformation in triaxial tests at different confining pressures in sandstones and limestone, which deform respectively in a fully brittle or a semi-ductile manner. This shows that the first signs of failure can be picked up before the yield point, i.e. before the time it is picked up by any of the traditional bulk stress-strain signals used in experimental rock deformation. In uniaxial compressive experiments on the same brittle sandstone samples we show that the loading pattern can affect the final strength but also the maximum acoustic emission amplitude. Cyclic loading tends to systematically reduce the magnitude of the largest induced seismic event, whilst simultaneously also promoting more complex fracture patterns and disintegration. This implies that the risk of induced seismicity can be mitigated by changing the loading pattern in subsurface operations. Finally, we show that for reactive rocks under the right pressure and temperature conditions, changing the chemistry can have an effect on rock strength, where the effects depend on the internal rock structure. This research increases the understanding of rock failure and show the potential of monitoring for a safe and efficient development of the subsurface.
Long-term analysis of the environmental impact of mining in the Upper Silesia Coal Basin area based on historical and the latest remote sensing data
Authors: Przyłucka Maria , Perski Zbigniew , Kowalski Zbigniew
Published: March 2022

The paper presents the results of long-term terrain subsidence monitoring in the mining area of the Upper Silesian Coal Basin (USCB) in Poland using Interferometry Synthetic Aperture Radar (InSAR), supplemented with differential analysis of digital elevation models. The work included analysis of mining-induced subsidence based on three archival surface models: historical terrain model obtained from the digitization of Messtischblatt topographic maps, representing the surface in 1919-1944; numerical terrain model DTED, derived from the vectorization of diaposites of topographic maps from the 90s of the twentieth century; LIDAR digital terrain model from 2013. Archival analyses were complemented by the newest PSInSAR database of Sentinel-1 data, processed for the entire area of USCB. The data covered a period of 6 years (October 26, 2014 - June 26, 2020), in which a total of 260 scenes from 124 descending paths were used. In the time domain, data were recorded at intervals of 12 days (for one Sentinel-1 satellite) or every 6 days for the full Sentinel-1 A / B constellation. The entire collection includes 8,139,901 PS points over 6,620 km2, giving an average density of about 1230 PS /sq km. The dataset enabled the analysis of contemporary vertical land movements. This huge set of various data was used to analyze the long-term influence of mining in the area broken down into time intervals, collectively covering the period from the mid-twentieth century to 2020. As a result of the analyzes, zones of mining-induced subsidence were developed, where the terrain surface was systematically changed in individual years. The data allowed for over 600 sq km identification under the influence of exploitation. Subsidence areas were matched with topographic data such as buildings and roads to estimate the effect of subsidence on urban areas. The work shows the great advantage of remote monitoring methods, which is the possibility of showing the long-term environmental impact to a large extent. The use of both historical and the latest data allowed for a comprehensive analysis of changes on the surface of the area now and in the past.
Evaluating hydrologic change for a set of European catchments by performance-based weighting of an ensemble of hydrologic and climate models
Authors: Sperna Weiland Frederiek , Visser Robrecht , Greve Peter , Bisselink Berny , Brunner Lukas , Weerts Albrecht
Published: March 2022

Hydrologic variability is expected to change throughout Europe due to climate change. However, ensemble projections of future changes in discharge show large variation because of the uncertainty in climate projections. The robustness of the change signal can potentially be improved by performance-based weighting. Here we analyze future change projections from an ensemble of three hydrological models (CWatM, LISFLOOD and wflow_sbm) forced with climate datasets from the Coordinated Downscaling Experiment - European Domain (EURO-CORDEX). The experiment focusses on nine river basins spread over Europe. The basins have different climate and catchment characteristics that strongly influence the hydrological response. We evaluate the ensemble consistency, the geographical variation therein and apply two weighting approaches; (1) the Climate model Weighting by Independence and Performance (ClimWIP) that focuses on meteorological variables and (2) the Reliability Ensemble Averaging (REA) that is here applied to catchment specific discharge statistics.

In Southern and Northern-Europe the ensemble consistency is high. There is a strong climate change signal. In Central Europe the differences between models are more pronounced. Analysis of the weighting method reveal that both weighting methods favor projections from similar GCMs and assign high weights to a single or few best performing GCMs.
The leaf-internal conductance to COS – a party crasher for the leaf relative uptake rate?
Authors: Spielmann Felix M. , Kitz Florian , Hammerle Albin , Gerdel Katharina , Alberti Giorgio , Peressotti Alessandro , Delle Vedove Gemini , Wohlfahrt Georg
Published: March 2022

In search for a constraint on the gross primary productivity (GPP) on ecosystem level, the sulfur containing gas carbonyl sulfide (COS) shows great promise. COS takes a very similar route into the leaf as carbon dioxide (CO2), that is through the leaf boundary layer, the stomata and the mesophyll until COS is fully catalyzed in a one-way reaction by the enzyme carbonic anhydrase (CA), whereas CO2 reaches its endpoint at RuBisCO within the chloroplast stroma. For the calculation of the GPP based on COS fluxes, a beforehand knowledge about the ratio of the deposition velocities of COS to CO2, also called leaf relative uptake (LRU), is needed. Differences in the LRU between plants and under different environmental conditions might hinder a straightforward usage of this approach.

To investigate the LRU and its dependencies on the involved conductances, we conducted eddy covariance measurements of COS, CO2 and H2O at an agricultural field in Ariis, Italy. At this field, 2 different varieties of soybean were planted in adjacent plots. One was the commercial variety Eiko, to which we will refer to as the green “wild type” (WT). The other was a chlorophyll deficient golden/yellow variety called MinnGold (MG). Due to a lack of rain, all plots were irrigated 2 and 3 weeks into our 4 week campaign.

Despite having a reduced chlorophyll content, MG was able to match and even exceeded the rate of photosynthesis of the WT during our observation period. While the GPP was similar for both varieties during the first week, we observed a higher decline for WT in week 2 due to a naturally occurring drought. Even after the irrigation of both plots, the GPP of MG recovered faster. We also observed considerably higher COS uptake by MG during the whole campaign. The resulting LRU under high light conditions was also consequently higher for MG (1.41) than for WT (0.97).
We calculated the aerodynamic, boundary layer, stomatal and internal conductance for both varieties and grouped the values into 4 phases: pre-drought, drought, rewetting and recovery. Based on these values and a linear perturbation analysis, we identified the internal conductance as the largest driver for the different LRUs between the two varieties.

Our results indicate that the stomatal conductance is not the only controlling factor for the LRU and that the mesophyll conductance can’t be neglected. We also show, the LRU response to drought differs between plants, even at the level of varieties. 
Reconstruction of GPR data using multiple-point geostatistics
Authors: Irving James , Zhang Chongmin , Gravey Mathieu , Mariéthoz Grégoire
Published: March 2022

A common challenge in the processing and analysis of ground-penetrating radar (GPR) reflection data is the reconstruction of missing traces. Gap filling, for example, may be required where data could not be recorded in the field in order to reduce artifacts produced during migration. Similarly, proper visualization and imaging of a GPR profile requires an even trace spacing, meaning that trace regularization is typically needed when the data are acquired in continuous mode using a fixed trace acquisition rate. Lastly, we may wish to increase the spatial resolution of a GPR dataset through trace densification, whereby new traces are reconstructed between existing ones, in order to improve data interpretability. 

A number of methods have been proposed for the reconstruction of missing GPR data over the past few decades, which vary in their degree of complexity and underlying assumptions. Simple strategies such as linear, cubic, and sinc interpolation can be highly effective, but only in the absence of spatial aliasing. When aliasing is present, other methods that exploit the predictability and/or sparseness of the GPR data, commonly in a transformed domain, may be utilized. However, such methods often involve overly simplistic assumptions about the data structure (e.g., that windowed portions of data can be described by sum of plane waves), which can lead to unrealistic and linear results as gaps in the data become large. Finally, all current reconstruction approaches lead to a single "best" estimate of the missing traces based on the existing measurements and some explicit or implicit choice of prior information, with no consideration of the corresponding uncertainty.

Here, we attempt to address these shortcomings by considering a GPR data reconstruction strategy based on the QuickSampling (QS) multiple-point geostatistical method. With this approach, GPR traces are simulated via sequential conditional simulation based on patterns that are observed in nearby high-resolution data (training images). To demonstrate the potential of this approach, we show its successful application to a variety of examples involving gap filling, regularization, and trace densification.
A new method to determine filtration of pollutants in urban soils
Authors: Fernandes Gersende , Di Prima Simone , Lipeme Kouyi Gislain , Angulo-Jaramillo Rafael , Martini Matteo , Lassabatere Laurent
Published: March 2022

Stormwater management zones must enable water to infiltrate easily, primarily due to macropores, but little is known about the transport of pollutants through these macropores. Some coupled methods using, for example, dyes, disc, or ring infiltrometers were developed to give insight on the respective contributions of the macropores versus the matrix to the bulk infiltration. However, these methods do not visualize where and how water infiltrates. Besides, no information is given on the solute transfer in soils, whereas this issue is crucial regarding the quality of soils and groundwater. One of the goals of the national program INFILTRON (https://infiltron.org) project granted by the French national research agency is to develop superparamagnetic iron oxide nanoparticles (SPIONs) which mimic both pollutant and bacteria flow behavior in soils (Raimbault et al., 2021) and are detectable by ground-penetrating radar (GPR). Within its framework (Lassabatere et al., 2020), we aim to show how nano-tracers can help detect preferential treatment flows (lithological heterogeneity, root system) and quantify or qualify the pollutant transfer in heterogeneous soils. A specific device was designed and presented for the concomitant monitoring of water infiltration and nano-tracer injection. This specific infiltrometer involves two water supply reservoirs and a ring diameter of 50 centimeters. This device maintains a constant depth of water (10 cm) above the soil and delivers the water infiltration into the soil. Two rules posed on the reservoirs allow monitoring the water drop and computation of the cumulative infiltration. Fifty volumes of SPIONs solutions (5 mL of 3.35g/l SPIONs solution) were injected into the ring to maintain a constant concentration in the ring. GPR monitors the bulb of infiltrated water and SPIONs. GPR data is treated with ReflexW (©Sandmeier geophysical research) and RockWorks (RockWare®) software. Combining this specific prototype with the use of GPR for the detection of water and the SPIONs gives insight into the processes of infiltration and SPIONs transfer and localization in the soil. These data allow us to understand and model pollutant transfer into the vadose zone.

Raimbault, J., Peyneau, P.-E., Courtier-Murias, D., Bigot, T., Gil Roca, J., Béchet, B., and Lassabatère, L.: Investigating the impact of exit effects on solute transport in macropored porous media, 2020, 1–20, https://doi.org/10.5194/hess-2020-494, 2020

Lassabatere, L., De Giacomoni, A.-C., Angulo-Jaramillo, R., Lipeme Kouyi, G., Martini, M., Louis, C., Peyneau, P.-E., Rodriguez-Nava, V., Cournoyer, B., Aigle, A., and others: INFILTRON package for assessing infiltration & filtration functions of urban soils, in: EGU General Assembly Conference Abstracts, 11269, 2020. https://doi.org/10.5194/egusphere-egu2020-11269
Study of end-user needs regarding behavior change to be more resilient to extreme weather events
Authors: Llasat-Botija Montserrat , Llasat Maria Carmen , Caballero-Leiva Isabel
Published: March 2022

Extreme weather events are increasing and will follow this trend due to climate change. In this scenario, adaptation, and mitigation in the face of them becomes essential both through technological innovations and through behavioural changes. In recent years, progress has been made in scientific knowledge on extreme hydrometeorological phenomena and climate change, and more funding is available for adaptation to climate change, both from European funds (e.g. Next Generation funds), country-level or regional funding. However, there are difficulties for to become this into a change in behaviors and actions to be more resilient to extreme phenomena both at the level of the general population and the public and private sector. This leads us to wonder if the knowledge and tools that are being generated are adjusted to the needs of these audiences in relation to adaptation and what are the facilities and barriers to carry out these changes towards more resilient patterns.

In order to analyze this aspect, a study has been carried out in which the viability and fitting of products and tools to improve the resilience of different type of end-users have been tested. For this, the first step was to conceptualize the tools and define hypotheses associated with them. The next step was to design the interviews to validate these hypotheses. Forty interviews were conducted with representatives of local administration, flood management companies, individuals, and so on. The interviews were customized to suit these different sectors and audiences. The answers served to validate or invalidate the starting hypotheses. In addition to the interviews, sources of expert information were consulted to identify similar strategies or tools and their level of success in their execution.

The interviews have made it possible to identify barriers to the implementation of changes both in individual habits (such as less interest than expected in attending participatory processes), and in organizations: budgetary limitations, political calendar or little knowledge/interest in knowing historical events. Motivations and interests were also identified, such as having a platform with centralized information on extreme phenomena or the prestige of collaborating with the academy to find optimal solutions to this problem.

This research has been done in the framework of the C3-Riskmed project (FEDER/MICINN-AEI/ PID2020-113638RB-C22) funded by the Spanish Ministry of Science and Innovation and EU Horizon 2020 project I-CHANGE (grant agreement 101037193).
High-sensitivity Earth System Models Most Consistent with Observations
Authors: Yuan Menghan , Leirvik Thomas , Storelvmo Trude , Phillips Peter , Alterskjær Kari , Smith Christopher
Published: March 2022

Earth’s transient climate response (TCR) quantifies the global mean surface air temperature change due to a doubling of atmospheric CO2, at the time of doubling. TCR is highly correlated with near-term climate projections, and thus of utmost relevance for climate policy, but remains poorly constrained. Within state-of-the-art Earth System Models (ESMs) participating in the Coupled Model Intercomparison Project (CMIP6), the TCR range (1.1 -2.9oC is much too wide to offer useful guidance to policymakers on remaining carbon budgets aligneded with the Paris agreement goals. To address this issue, we here present an observation-based TCR estimate of 1.9-2.7oC (95% confidence interval). We show that this method correctly diagnoses TCR from 22 CMIP6 ESMs if the same variables are taken from the ESMs as are available from observations. This increases confidence in the new estimate and range, which are higher and narrower, respectively, than those of the CMIP6 ensemble.
A Bayesian framework to derive consistent intensity-duration-frequency curves from multiple data sources 
Authors: Thorarinsdottir Thordis , Roksvåg Thea , Lutz Julia , Grinde Lars , Dyrrdal Anita
Published: March 2022

As a warming climate leads to more frequent heavy rainfall, the importance of accurate rainfall statistics is increasing. Rainfall statistics are often presented as intensity-duration-frequency (IDF) curves showing the rainfall intensity (return level) that can be expected at a location for a duration, and the frequency of this intensity (return period). IDF curves are commonly constructed by fitting generalized extreme value (GEV) distributions to observed annual maximum rainfall for several target durations, where the available observation data sources may vary for the different durations. As the estimation is performed independently across durations, the resulting IDF curves may be inconsistent across durations and return periods. We discuss how consistent estimates across the different durations may be derived by post-processing independently obtained Bayesian posterior distributions for each duration. The proposed methods are evaluated for simulated data and for Norwegian rainfall data from 83 locations, for 16 durations between 1 minute and 24 hours, where the post-processing yields consistent and accurate estimates.
Monitoring a submarine strike-slip fault, using a fiber optic strain cable
Authors: Gutscher Marc-Andre , Royer Jean-Yves , Graindorge David , Murphy Shane , Klingelhoefer Frauke , Gaillot Arnaud , Aiken Chastity , Cattaneo Antonio , Barreca Giovanni , Quetel Lionel , Riccobene Giorgio , Aurnia Salvatore , Margheriti Lucia , Moretti Milena , Krastel Sebastian , Petersen Florian , Urlaub Morelia , Kopp Heidrun , Currenti Gilda , Jousset Philippe
Published: March 2022

The goal of the ERC (European Research Council) funded project - FOCUS is to apply laser reflectometry on submarine fiber optic cables to detect deformation at the seafloor in real time using BOTDR (Brillouin Optical Time Domain Reflectometry). This technique is commonly used monitoring large-scale engineering infrastructures (e.g. - bridges, dams, pipelines, etc.) and can measure very small strains (<< 1 mm/m) at very large distances (10 - 200 km), but until now has never been used to study tectonic faults and deformation on the seafloor.

Here, we report that BOTDR measurements detected movement at the seafloor consistent with ≥1 cm dextral strike-slip on the North Alfeo fault, 25 km offshore Catania, Sicily over the past 10 months. In Oct. 2020 a dedicated 6-km long fiber-optic strain cable was connected to the INFN-LNS (Catania physics institute) cabled seafloor observatory at 2060 m depth and deployed across this submarine fault, thus providing continuous monitoring of seafloor deformation at a spatial resolution of 2 m. The laser observations indicate significant elongation (20 - 40 microstrain) at two fault crossings, with most of the movement occurring between 19 and 21 Nov. 2020. A network of 8 seafloor geodetic stations for direct path measurements was also deployed in Oct. 2020, on both sides of the fault to provide an independent measure of relative seafloor movements. These positioning data are being downloaded during ongoing oceanographic expeditions to the working area (Aug. 2021 R/V Tethys; Jan. 2022 R/V PourquoiPas) using an acoustic modem to communicate with the stations on the seafloor. An additional experiment was performed in Sept. 2021 using an ROV on the Fugro vessel Handin Tide, by weighing down unburied portions of the submarine cable with pellet bags and sandbags (~25kg each) spaced every 5m. The response was observed simultaneously by DAS (Distributed Acoustic Sensing) recordings using two DAS interrogators (a Febus and a Silixa). The strain caused by the bag deployments was observed using BOTDR and typically produced a 50 - 100 microstrain signal across the 120 meter-long segments which were weighed down. In Jan. 2022 during the FocusX2 marine expedition, 21 ocean bottom seismometers were deployed for 12-14 months, which together with 15 temporary land-stations as well as the existing network of permanent stations (both operated by INGV) will allow us to perform a regional land-sea passive seismological monitoring experiment.
Local Cascade and Dissipation: The Coarse Graining approach as a robust tool to investigate Magnetic Reconnection
Authors: Manzini Davide , Sahraoui Fouad , Califano Francesco
Published: March 2022

We derive the coarse-graining (CG) equations of  incompressible Hall Magnetohydrodynamics (HMHD) turbulence to investigate the local (in space) energy cascade rate as a function of the filtering scale. 
First, the CG equations are space averaged to obtain the analytical expression of the mean cascade rate. Its application to 3 dimensional (3D) simulations of (weakly compressible) HMHD shows a cascade rate consistent with the value of the mean dissipation rate in the simulations and with the classical estimates based on the "third-order" law.

 The strength of the CG approach is further revealed when considering the local-in-space energy cascade rate which is shown theoretically and numerically to match dissipative processes at a given position x, when both quantities are locally averaged over a small neighboring region (quasi-locality). This result supports the claim that the (quasi-)local cascade rate can provide a reliable estimate of the (quasi-)local energy dissipation, regardless of the nature of the dissipation processes involved.

The new model is further applied to magnetic reconnection sites observed in Hybrid-Vlasov (HVM) simulations and in spacecraft data. The results show the robustness of the new model over standard tools used to highlight energy dissipation processes and particles energization at the X points.  
Threshold of aeolian and fluvial nonsuspended sediment transport along arbitrarily sloped beds from an analytical model of periodic grain motion
Authors: Chen Yulan , Pähtz Thomas
Published: March 2022

The downslope component of the gravitational force affects the threshold and direction of sediment transport along an arbitrarily sloped bed. It plays an important role for the shape and stability of river channels, and for the formation, evolution, and morphology of aeolian and fluvial bedforms. Here, we generalize an existing model of the threshold of nonsuspended sediment transport, which unifies aeolian and fluvial transport conditions using an analytical description of flow-driven periodic grain motion, to account for arbitrarily sloped beds. Without any readjustment of the model parameters, the generalized model captures the experimentally measured bed slope effect on the transport threshold much better than previously proposed models based on incipient grain motion, especially for large bed slopes in the direction transverse to the driving flow. This is mostly because drag resistance counteracts the transverse average motion of transported grains, which in the model has the same mathematical effect as a reduction of the transverse bed slope. For aeolian transport, the model predicts substantial gravity-induced transverse diffusion of saltating grains, neglected in previous studies, which may explain why aeolian barchan dunes generally tend to have a larger width than length.
Dynamics of the euphotic zone in the Black Sea: The synergy of data from profiling floats, machine learning and numerical modeling 
Authors: Stanev Emil , Wahle Kathrin , Staneva Joanna
Published: March 2022

Data from profiling floats in the Black Sea revealed complex temporal and spatial relationships between physical variables on the one hand and oxygen, chlorophyll (Chl-a) and the backscattering coefficient at 700 nm (bbp) on the other. It was demonstrated that the temperature-stratified upper layer and salinity-stratified layers below 50 m provide the ecological niche responsible for the major variability of the BGC system in the euphotic layer. There, around the depth of the minimum potential vorticity, the subsurface chlorophyll maximum presents a major BGC characteristics. Data analysis revealed some limits in understanding the details of BGC dynamics, as well as their dependence on physical drivers. One example is the fact that while bbp and Chl-a weakly follow the long-term changes in temperature and salinity, their responses to individual cooling events appear much stronger than what is observed in the physical fields. To fully account for different interdependences, a feedforward backpropagation neural network (NN) was used. The NN learnes from data recorded by profiling floats and predicts BGC states using physical measurements only. The skill was very high, particularly for oxygen, but it reduced when the NN was applied to older data because the interrelationships between the physical and BGC properties have changed recently. One indication of such change is the missing overshooting of either Chl-a or bbp penetration depth in winter reported in earlier studies. The BGC states reconstructed by the NN from physical data produced by a coupled physical-BGC operational model outperform the BGC output of the same coupled model. Therefore, the use of data from profiling floats, physical properties from numerical models and NN appeared a powerful tool to reconstruct the 4D dynamics of euphotic zone. Basin wide patterns and temporal variabilities of oxygen, bbp and Chl-a are also analyzed. Of particular interest is the reconstruction of short-living BGC features, particularly in the area of coastal anticyclones, which are difficult to observe basin-wide with available floats.
Magnetic fabric study of the Dejvice loess/paleosol sequence (Prague, Czech Republic)
Authors: Chadima Martin , Žatecká Michaela , Kolaříková Kristýna , Bradák Balazs , Kadlec Jaroslav
Published: March 2022

In this contribution, we present a rock magnetic and magnetic fabric study of the Dejvice loess/paleosol sequence with an aim to demonstrate how rock magnetic methods can be very effective tools for detecting paleoenvironmental, pedogenic, and post-depositional processes. This study covers the 15-meter-long loess/paleosol section which was recently temporarily accessible during the underground construction works in the Vienna House Diplomat Hotel in Prague. The exposed part of the sequence contained at least four different paleosol horizons and covered the time interval from ca. 130 ky to recent. For the purpose of this study, 425 orientated samples (8 ccm) were collected evenly covering the studied section.

In general, loess sequences contain variable amount of detrital magnetic particles derided from the source material. In addition, in warmer interglacials periods, pedogenesis results in formation of paleosol horizons which are magnetic enhanced by the in-situ neo-formed nanoscale ferromagnetic particles.

The applied rock-magnetic techniques included measurements of (1) magnetic susceptibility (MS), (2) frequency-dependent susceptibility (kFD), (3) out-of-phase magnetic susceptibility (opMS), and (4) viscous magnetization (Mv). While MS very sensitively reflects the relative amount of all magnetic particles, the other methods (kFD, opMS, and Mv) mirror solely the contribution of the neo-form nanoscale particles. In addition to these rock magnetic parameters, (5) anisotropy of magnetic susceptibility (AMS) was measured in order to obtain magnetic fabric reflecting the preferred orientation of magnetic minerals. Magnetic fabric can be primarily interpreted in terms of paleotransport directions but it may also provide some evidences for post-depositional reworking and/or movements.

All paleosol horizons possess significantly higher values of MS, kFD, opMS and Mv. This indicates that the increased amount of magnetic particles in paleosols is exclusively due to the magnetic enhancement caused by the neo-formation of nanoscale particles during pedogenesis. In addition, the values of kFD, opMS, and Mv mutually intercorrelate very tightly. This indicates that all these independent methods are reliable proxies for the quantification of ultra-file particles in loess/paleosols horizons.

In addition of the paleotransport direction, the magnetic fabric reflects secondary sedimentary processes. This involves the displacement of clastic particles by flowing water and the redeposition of the material along the slope. The direction of movement of these sediments corresponds to the current geomorphology of the surroundings. We can conclude that the section was not deposited solely by the aeolian processes.
Modelling the urban heat island of London, and implications for heat-related mortality during the 2018 summer heatwave
Authors: Brousse Oscar , Simpson Charles , Kenway Owain , Heaviside Clare
Published: March 2022

The impact of cities on the local climate is a well-known and -studied phenomenon. In particular, cities increase local air temperature, particularly at night, and creating what is called the urban heat island (UHI). The UHI in the UK’s capital city of London was one of the first to be quantified by Luke Howard around 1830. Since then, many studies have measured, or modelled, the impact of urbanization on local temperatures, and considered the potential impacts on heat-related mortality. Nevertheless, these studies are often: i) focused on short-time periods – e.g., constrained to few days of heatwave; ii) lack spatial density and/or representativity of measurements; or iii) don’t report a method that would make their results and outcomes comparable to other cities.

Our aim is to make coherent spatio-temporal estimations of the burden that cities bring in terms of heat-related mortality. To achieve this, we ran two 3-months (June to August) regional climate simulations at 1 km horizontal resolution using the Weather and Research Forecasting (WRF) which consist of two simple scenarios: with and without the city. For both scenarios, the model was parameterized using the new standardized WUDAPT-TO-WRF python tool. In the natural scenario, surrounding natural pixels from MODIS were considered most probable land covers and replace the city. In the urban scenario, urban canopy parameters were obtained from the European Local Climate Zones (LCZ) map. We used the complex three-dimensional Building Effect Parameterization urban canopy model with its Building Energy Model (BEP-BEM) to represent the urban effect in the urban scenario. The simulations were run for the 2018 summer and its 4 heatwaves over London and the south east of England. The model was evaluated for its urban scenario against a variety of earth observations and meteorological measurements from official and crowd-sourced data. Finally, we bias-corrected the urban and the natural scenario using an innovative method that relies on official automatic and citizen weather stations. This way, me make sure that the calculated heat anomaly induced by the city is as representative as possible , and allows us to quantify the proportion of heat related mortality which we attribute to the urban heat island in London.

Our study is considered one of the first to model a whole seasonal impact of a city on its local climate using a highly complex urban canopy model and a standardized method of parameterization. Our bias-correction method is also expected to provide key perspectives on the joint utility of modelled and crowd-sourced weather data for heat-related epidemiological studies.
FLEXPART model sensitivity study for the footprint of a Swiss tall tower site
Authors: Plach Andreas , Leuenberger Markus , Stohl Andreas
Published: March 2022

Flux towers are essential tools for collecting measurements of trace gas concentrations/fluxes to investigate source regions of greenhouse gases (GHGs) and other pollutants. Most flux towers provide observations at heights of several meters to tens of meters and therefore only sample potential source regions in their immediate vicinity, i.e., these towers have small so-called footprints. Here we are interested in estimating the footprint of one of the few European tall towers located close to Beromünster, Switzerland. The tower was initially set up as a CarboCount CH site — a dense GHG observation network run for four years (2012 - 2015) — and is continued since by the University of Bern. Measurements are taken at an altitude of 212m above ground. This relatively high observation height results in a larger tower footprint and therefore the tower observations are predestined for a source analysis on a much larger scale than typical for flux towers.

We will present preliminary results of a sensitivity study performed with the Lagrangian atmospheric transport model FLEXPART using different meteorological input data of various spatial resolution, different model internal time step settings, as well as two
different convection schemes used in the convective atmospheric boundary layer — a Gaussian Hanna-type turbulence model and a more realistic skewed turbulence scheme in which a larger area is occupied by downdrafts than by updrafts.

The range of simulated footprints will be used in combination with emission inventories of CO2 and CH4 to simulate observations at the tower. By comparing the simulated with the actual observations at the tower we aim to evaluate the quality of the simulated footprints for the respective input data and model setting.
Nitrate isotopes reveal the effectiveness of riparian denitrification for nitrate removal from riparian zones
Authors: Lutz Stefanie , Musolff Andreas , van Breukelen Boris , Knöller Kay , Fleckenstein Jan
Published: March 2022

The riparian zone is a hydrologically and biogeochemically active zone, characterized by mixing of stream water with groundwater and transformation of nutrients such as nitrogen. The riparian zone thus plays a key role in natural attenuation of nitrate pollution. Among the attenuation processes in riparian zones, denitrification is the only one that leads to permanent removal of nitrogen from the riparian system via the release of dinitrogen gas into the atmosphere. In contrast, other biogeochemical processes such as nitrate uptake by plants merely result in a temporary nitrogen retention within riparian zones. While hydrochemical data and endmember modelling can help assess nitrate transformation in riparian aquifers, this does not allow quantifying the extent of nitrate removal via denitrification. In this talk, I will demonstrate how nitrate isotope data can be used in combination with chloride and nitrate concentration data to quantify spatial and temporal variations in the extent of denitrification and mixing between groundwater and surface water. I will illustrate how the application of this approach to a riparian groundwater study site in Central Germany revealed that denitrification is largely exceeded by other processes that merely lead to temporary nitrate removal from the riparian groundwater. In comparable settings, a major fraction of nitrogen inputs is thus likely retained in riparian zones and may eventually be discharged into rivers. Such information is crucial to determine the effectiveness of riparian zones for removing nitrate from aquatic ecosystems, which is highly relevant for many river ecosystems at risk of eutrophication because of high nitrogen inputs from agriculture.

Reference

Lutz, S. R., Trauth, N., Musolff, A., Van Breukelen, B. M., Knöller, K., & Fleckenstein, J. H. (2020). How important is denitrification in riparian zones? Combining end-member mixing and isotope modeling to quantify nitrate removal from riparian groundwater. Water Resources Research, 56, e2019WR025528. https://doi.org/10.1029/2019WR025528
Forecasting Large Hail Using Logistic Models and the ECMWF Ensemble Prediction System
Authors: Battaglioli Francesco , Groenemeijer Pieter , Tsonesvky Ivan
Published: March 2022

An additive logistic regression model for large hail was developed based on convective parameters from ERA5 reanalysis, severe weather reports from the European Severe Weather Database (ESWD), and lightning observations from the Met Office Arrival Time Difference network (ATDnet). This model was shown to accurately reproduce the spatial distribution and the seasonal cycle of observed hail events in Europe. A spatial map of the modelled mean distribution for hail > 2 cm will be presented.

To explore the value of this approach to medium-range forecasting, a similar statistical model was developed using four predictor parameters available from the ECMWF Ensemble Prediction System (EPS) reforecasts: Mixed Layer CAPE, Deep Layer Shear, Mixed Layer Mixing Ratio and the Wet Bulb Zero Height. Probabilistic large hail predictions were created for all available 11-member ensemble forecasts (2008 to 2019), for lead times from 12 to 228 hours.

First, we evaluated the model’s predictive skill depending on the forecast lead time using the Area Under the ROC Curve (AUC) as a validation score. For forecasts up to two to three days, the model highlights a very high predictive skill (AUC > 0.95). Furthermore, the model retains a high predictive skill even for extended forecasts (AUC = 0.85 at 180 hours lead time) showing that it can identify regions with hail potential well in advance. Second, we compared the forecast spatial probabilities at various lead times with observed hail occurrence focusing on a few recent hail outbreaks. Finally, our four-dimensional model was compared with logistic models based on composite parameters such as the Significant Hail Parameter (SHP) and the product of CAPE and Deep Layer Shear (CAPESHEAR). The four-dimensional model outperformed these composite-based ones at lead times up to four days. The high AUC scores show that this model could improve short-medium range hail forecasts. Preliminary application of this approach to other convective hazards such as convective wind gusts will be presented as well.