bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon dioxide dynamics in a boreal forest ditch affected by clear-cut forestry
Authors: Zannella Alberto , Eklöf Karin , Laudon Hjalmar , Maher Hasselquist Eliza , Wallin Marcus
Published: March 2022

Boreal water courses are large emitters of carbon dioxide (CO2) to the atmosphere. In Sweden, a high share of these water courses are man-made ditches, created to improve drainage and increase forest productivity. Previous studies from boreal regions have mainly suggested that terrestrial sources sustain the CO2 in these ditches and with variability in hydrology as the main temporal control. However, few studies have quantified ditch CO2 dynamics in harvested catchments. An altered hydrology, increased nutrient export and light availability upon forest harvest are all factors that potentially can change the main source control. Thus, there is a strong need to better understand how clear-cut forestry affects the ditch CO2 dynamics in boreal regions.

Here, high-frequency (30 min) CO2 concentration dynamics together with other hydro-chemical variables were studied in a forest ditch draining a fully harvested catchment in the Trollberget Experimental Area, northern Sweden. Data were collected during the snow-free season from May to October. Ditch CO2 concentrations displayed a clear seasonal pattern with higher CO2 during summer than in spring and autumn. Concentrations were ranging from 0.41 to 3.99 mg C L-1 (median: 1.69 mg C L-1, corresponding to partial pressures (pCO2) of 2553 μatm, IQR = 1.08 mg C L-1). Strong diel cycles in CO2 were developed during early summer, with daily amplitudes in the CO2 reaching up to 2.1 mg C L-1. These daily cycles in CO2 were likely driven by aquatic primary production consuming CO2 during daytime. In addition, individual high-flow events in response to rainfall had a major influence on the ditch CO2 dynamics with generally a diluting effect, but the strength in the CO2-discharge relationship varied among seasons and between events. It was evident from the study that growing season CO2 dynamics in forest ditches affected by clear-cut forestry are high and controlled by a combination of hydrological and biological factors. These high dynamics and the associated controls need to be considered when scaling ditch CO2 emissions across boreal landscapes affected by clear-cut forestry.
Acoustic signals from the 2021 Cumbre Vieja eruption
Authors: Cigala Valeria , Kueppers Ulrich , Vossen Caron E. J. , Barrancos José , Spina Laura , Fee David , Cimarelli Corrado , Gestrich Julia , Schmid Markus , Hernández Pedro , Pankhurst Matthew , D'Auria Luca , Pérez Nemesio , Dingwell Donald B.
Published: March 2022

After 50 years of volcanic quiescence, on 19 September 2021, an eruption started on the western flank of the Cumbre Vieja ridge of La Palma, Canary Islands, Spain. The eruption was characterised by simultaneous effusive and explosive activity from a several hundred-meter-long fissure, which later built up a cone and showed variable eruptive behaviour at different vents, suggesting a spatially complex plumbing system. Explosive eruptive activity ranged from mild ash emissions, Strombolian explosions to fire fountaining episodes.

We carried out field measurements to study the variable explosive eruptive activity and associated acoustic signals. A single microphone initially deployed at about 2 km SW of the vents from 6 to 11 October was later replaced by an array of 3 microphones from 6 November to 13 December at about 300 m W of the microphone location in October. The microphones (PCB ½” free field acoustic sensors, 3.15-20 kHz frequency range) were each connected to an OptiMeas SmartPro digitiser continuously sampling at 5000 Hz. The digitisers are GPS synchronised for accurate acoustic array processing. The acoustic array was complemented by a thunderstorm detector continuously recording (since 11 October) lightning and electrical activity generated by the volcanic explosions (Vossen et al., 2022). Additionally, at the beginning of November 2021, thermal videos of the eruptive activity were acquired.

Preliminary analysis of the large and unique acoustic dataset shows varying waveforms indicating evolving source conditions: eruption intensity, source mechanism, vent geometry, fragmentation depth and amount of ash ejected. Moreover, we observe a variability of frequency (peak and mean) and amplitude with time. Further analysis includes the characterisation of the acoustic source location within the growing volcanic edifice and the comparison and correlation with lightning and thermal infrared data to detail changes in explosive activity related to the evolving eruption sources. 

Caron E.J. Vossen et al. (2022), Electrical activity of the 2021 Cumbre Vieja eruption, EGU22-8052.
on GNSS-IR technique for measuring shallow sediment compaction
Authors: Karegar Makan
Published: March 2022

The solid Earth aspects of relative sea-level change can dominate in low-lying coastal areas with potentially vulnerable to accelerating rates of sea-level rise. Global Navigation Satellite System (GNSS) as companion tools to tide gauges allow long-term assessment of solid Earth deformation, thus essential for disclosing climate-forced mechanisms contributing to sea-level rise (SLR). So far, it has not been possible to measure shallow displacements that occur above the base of GNSS monument because conventional positioning determines the vertical component of position changes resulting from displacements occurring beneath the foundation. We use an emerging technique, GNSS interferometric reflectometry (GNSS-IR), to estimate the rate of this process in two coastal regions with thick Holocene deposits, the Mississippi Delta and the eastern margin of the North Sea. We show that the rate of land motion from shallow compaction is comparable to or larger than the rate of SLR. Since many of the world's great coastal cities are built on river deltas with comparable Holocene sections, our results suggest that estimates of flood risk and land loss have been underestimated. We demonstrate environmental impact of parking lots and streets surrounding several monitoring sites on GNSS measurements. Such kinematic environments will perturb the amplitude of reflected signals to GNSS sensors and leave time-variable imprints on GNSS observations. Thus, obtaining desirable reflections for shallow subsidence monitoring could be challenging.
Improving crop representation in an ecohydrological model: a proof of concept
Authors: Buckley Paules Jordi , Paschalis Athanasios , Fatichi Simone , Warring Bonnie
Published: March 2022

Agricultural crops represent some 10% of the Earth’s land surface and their sustainable management is key to maintain ecosystem services and ensure food security. Arguably, the first step towards successful management of these croplands is a detailed understanding of their intricate energy,water,carbon and nutrient dynamics. This is best achieved via mechanistic ecohydrological modeling which facilitates the study of explicit processes such as crop growth and nutrient leaching. For example, this method allows us to investigate soil biogeochemical cycling under different fertilization practices which would otherwise be challenging using an alternative empirical modelling approach. 

In this proof of concept study, we expand the T&C ecohydrological model to represent agricultural crops and the associated soil biogeochemical dynamics. This is accomplished via the introduction of a new model component which represents individual crop dynamics. Specifically, we develop new algorithms to represent crop-specific phenology, crop-specific carbon allocation schemes,  as well as crop-specific management practices which span from sowing to fertilization to harvest. We apply T&C-crop to three agricultural catchments in the UK. Model validation is performed for several crop types in terms of leaf area dynamics, crop yield, hydrological dynamics and downstream nitrogen release. 
From agriculture to forests: restoring fertility and biodiversity of exploited soils
Authors: Michele Innangi , Fioretto Antonietta , Guggenberger Georg , De Castro Olga , De Luca Daniele , Di Iorio Emanuela , Danise Tiziana
Published: March 2022

The issue of exploited soils that become unproductive after extended agriculture use is constantly growing and it is considered of great interest on a global level. Soil degradation induces loss of important ecosystem services and biodiversity, which is aggravated by the on-going climate change. Here, we investigated the chances of reforestation of an exploited soil as a possible nature based solution to this problem. We aimed at identifying a type of forest management capable of requalifying these soils. For that, we investigated a site in Central Italy characterized by a mixed-species plantation represented by tree different associations consisting of particular ancillary species, namely Alnus cordata, Elaeagnus umbellata (both N-fixing species), and Corylus avellana, in association with valuable species, such as Populus alba and Juglans regia planted on a former agricultural land. The criteria for the  improvement of soil quality was an increase in organic matter and biodiversity. We evaluated how the relationship between soil chemical and biological parameters varied among different intercropping systems and in a conventional agricultural field. We tested topsoil (0-10 cm) total organic carbon, total nitrogen, lignin and cellulose, as well as biological parameters such as fluorescein diacetate hydrolase (FDAH) enzyme activity, and fungal biodiversity by using a DNA metabarcoding approach. The comparison with the agricultural field revealed that revegetation led to an increase in both carbon and nitrogen as well as FDAH activity and fungal diversity. In this context, ancillary species could play a key role in restoring degraded soils quality, whereas N-fixing species Alnus cordata increased both soil fertility and biodiversity compared to the agricultural field and to other tree associations.

 
Application of the spectral cloud microphysics model COSMO-SPECS for sensitivity studies in real mixed-phase cloud scenarios
Authors: Schrödner Roland , Bühl Johannes , Senf Fabian , Knoth Oswald , Stoll Jens , Simmel Martin , Seifert Patric
Published: March 2022

Within mixed phase clouds several microphysical processes exchange water between the three compartments vapor, liquid phase (cloud and rain droplets) and ice phase (ice and snow crystals). In the recent years, mixed-phase clouds were observed at different places on Earth with contrasting aerosol conditions using the remote sensing platform LACROS. The microphysical properties of these mixed phase clouds depend strongly on the availability of particles that serve as cloud condensation nuclei and ice nucleating particles.

The SPECtral bin cloud microphysicS model SPECS was developed to simulate cloud processes using fixed-bin size distributions of aerosol particles and of liquid and frozen hydrometeors. It was implemented in the numerical weather prediction model COSMO, thereby substituting the original bulk one- or two-moment microphysics. Recently, the COSMO-SPECS has been enhanced by considering lateral boundary conditions for the hydrometeor spectra allowing for high-resolution real case studies on nested domains. Furthermore, an additional INP spectrum is introduced, which better enables the future coupling to INP diagnosed from aerosol chemistry transport model simulations.

The simulations are carried out by first applying the meteorological driver COSMO using its standard two-moment microphysics scheme on multiple nests with increasing horizontal resolution. Finally, COSMO-SPECS is applied on the innermost domain with a horizontal resolution of a few hundred meters using boundary data derived from the finest driving COSMO domain. For this purpose, the bulk hydrometeor fields of the driving model need to be translated into the corresponding hydrometeor mass and number distributions of SPECS’ hydrometeor spectra.

Detailed sensitivity studies on properties of the aerosol (CCN, INP, ice crystal shape) and on the treatment of the hydrometeor fields at the lateral boundaries for selected observed mixed-phase cloud cases are presented. The model simulations are compared against available remote sensing observations. Overall, the spectral cloud microphysics show improvements in the formation of precipitation for the investigated cases. However, the simulations depend strongly on the given meteorological conditions provided by the outer driving model domains. 
“climatearchive.org”: 540 million years of climate data at your fingertips
Authors: Steinig Sebastian , Alexander Tessa , Lunt Dan , Valdes Paul , Duggan Zak , Lee Patrick , Navratil Jakub , Offokansi Ikenna , Swann Matthew
Published: March 2022

We can only fully understand the past, present and future climate changes by bringing together data and process understanding from a broad range of environmental sciences. In theory, climate modelling provides a wealth of data of great interest to a wide variety of disciplines (e.g., chemistry, geology, hydrology), but in practice, the large volume and complexity of these datasets often prevent direct access and therefore limit their benefits for large parts of our community.

We present the new online platform “climatearchive.org” to break down these barriers and provide intuitive and informative access to paleoclimate model data to our community. The current release enables interactive access to a recently published compilation of 109 HadCM3BL climate model simulations. Key climate variables (temperature, precipitation, vegetation and circulation) are displayed on a virtual globe in an intuitive three-dimensional environment and on a continuous time axis throughout the Phanerozoic. The software runs in any web browser — including smartphones — and promotes data exploration, appeals to students and generates public interest.

We also show current work on the next phase of the platform, which aims to develop new tools for integration into a more quantitative research workflow. These include easy online generation and download of maps and time series plots of the underlying monthly model data. The data can also be exported as global fields or CSV files for any user-selected location for further offline analysis, such as use in spreadsheets. Finally, we will discuss and outline future integration of new sources of model and geochemical proxy data to simplify and advance interdisciplinary paleoclimate research.
The Operational Cloud Products for Sentinel-5 Precursor and Sentinel-4 and comparisons with GEMS
Authors: Lutz Ronny , Molina Garcia Victor , del Aguila Ana , Romahn Fabian , Loyola Diego
Published: March 2022

The status and most recent developments of the operational L2 Cloud product will be presented in this contribution for the ongoing Sentinel-5 Precursor and upcoming Sentinel-4 missions. These Copernicus missions are focused on atmospheric composition, operate in the UV/VIS/NIR/(SWIR) spectral region and comprise the retrieval of trace gases, greenhouse gases, aerosol and cloud properties. A good knowledge about the latter, i.e. the presence and characteristics of clouds, is a pre-requisite for an accurate retrieval of the aforementioned trace gases and greenhouse gases. Additionally, clouds are by themselves an interesting indicator to measure and monitor because of their contribution to the radiation budget, and hence, impact on climatological applications. 
The algorithms for retrieving the operational cloud products from TROPOMI onboard Sentinel-5 Precursor and the UVN spectrometer onboard Sentinel-4 are called OCRA (Optical Cloud Recognition Algorithm) and ROCINN (Retrieval of Cloud Information using Neural Networks) and both have their heritage with GOME/ERS-2 and GOME-2 MetOp-A/B/C, where they have already been successfully implemented in an operational environment. OCRA applies a broad band color space approach to the measured reflectance in order to retrieve a radiometric cloud fraction that is used as an a priori input to ROCINN, which retrieves cloud top height, cloud optical thickness and cloud albedo from measurements of sun-normalized radiances in the NIR in and around the oxygen A-band. The cloud parameters retrieved by ROCINN are provided for two different cloud models. The Clouds-as-Layers (CAL) model treats clouds as layers of scattering water droplets, which is physically more realistic than the second model, Clouds-as-Reflecting Boundaries (CRB), which treats a cloud as a simple Lambertian reflector.
In addition, this contribution will cover initial results of applying the OCRA algorithm to the recently launched Korean geostationary GEMS instrument. Applying the algorithm to GEMS does provide a great opportunity to test the performance under a geostationary configuration and to transfer lessons learned in a synergetic way to the Sentinel-4 development. Also, initial comparisons of the S5P and GEMS cloud products will be shown.
Assessing local site response using earthquake data: The case of thick buried low-velocity layers
Authors: Farrugia Daniela , Galea Pauline , D'Amico Sebastiano
Published: March 2022

In the past decade, studies to determine amplification effects due to the local geology have been conducted in the Maltese islands (Central Mediterranean) by means of ambient noise techniques. Particular areas of interest include the north and north-western areas of the islands which are characterised by clay, that can reach a thickness of 75 m, buried beneath limestone.  This introduces a velocity inversion in the stratigraphy and consistent, characteristic peaks in the H/V spectral ratios. With the expansion of the Malta Seismic Network (MSN) to these geological areas of concern, the possibility of confirming and further investigating the results using empirical data arises. Here we present results, mainly in terms of Standard Spectral Ratio (SSR) and earthquake H/V, using 3 years of earthquake data at three stations of the MSN. In particular we note that the amplifications obtained using the SSR technique are significantly higher than those obtained using both noise and earthquake H/V techniques. While the peaks observed in the H/V spectra are also reproduced in the SSR curves using earthquake data, the latter exhibit important additional peaks at frequencies below 1 Hz, whose amplitude may be as high as 30. By separating the earthquake data set on the basis of distance from the islands, we show that the amplification is source-dependent, and that the high amplification values originate from larger, more distant earthquakes in the Hellenic arc. This has important implications for seismic hazard determination.
First steps to countering “ocean blindness” in an alpine region: lessons learned from ocean literacy activities across a wide age group
Authors: Borrione Ines
Published: March 2022

Environmental education in schools (from child-care to high-school) mostly focuses on teaching features and processes that characterize the local natural environment, so that the geographical context strongly affects what children and older students (and their families) may learn and know about the surroundings and which actions need be taken to protect and conserve it. As a consequence, the community living in a mountain region is less prone to learning about the sea or the ocean, about its main physical, chemical and biological charachteristis, and about the processes that regulate them and how or why day-to-day actions affect the ocean's health and sustainability – the so called “ocean blindness”. Such considerations have led to the organization of a small set of pilot Education and Outreach activities that have been carried out in the schools of the province of Biella, a small-sized city located in the foot-hill of the Alps, 300m above sea-level, and about 200 km away from the nearest coast. These school activities/projects involved a very wide age group, including child care (ages 1-3), kindergarten (ages 3 to 5), elementary (ages 6 to 10) and high-school (ages 14-17) and were aimed at teaching basic marine science concepts learned from more than 10 years of experience as an oceanographer. This contribution presents the results and lessons learned from the first activities carried out in 2021 also providing an example of activities that can be carried out in similar contexts, and of hands-on resources that are available also when operating far away from the coast.
Implications on source localization and central depth of anisotropy beneath the Sikkim Himalaya: an appraisal on lithospheric deformation
Authors: Biswal Satyapriya , Dey Gourab , Mohanty Debasis D
Published: March 2022

For the understanding of deformational mechanism and geodynamics of a tectonic set up, the source localization and central depth of anisotropy plays a vital role. Though mantle dynamics and deformation patterns can be understood from studying the shear wave splitting mechanism, the true interpretation of under earth mechanism governing the geodynamics remains little biased and unrealistic without the  proper justification and identification of the source localization and depth of anisotropy. Our present study is focused on the possible central depth determination and source localization of anisotropy beneath the Sikkim Himalayan region based upon the well-established spatial coherency method of Splitting parameters, an improved and dynamic principle of grid search analysis based on the Fresnel zone concept. The principle is based upon the maximum coherency relation between the splitting parameters suggested by a minimization in the variation factor as a function of true depth of the anisotropy. Sikkim Himalaya, sandwiched between the central Nepal Himalaya and the eastern Bhutan Himalaya, demarcates the distinct change in the width of the Himalayan foreland basin and the Main Himalayan Thrust (MHT), which is a part of the active deforming eastern Himalayan fold axis and thrust belt. The Spatial coherency analysis of splitting parameters suggests the central depth of heterogeneity at around 130 km beneath this Sikkim Himalayan region as a consequence of the deformation patterns governed by the complex lithospheric mass at this particular depth.

 

KEYWORDS

Spatial coherency, Shear wave splitting, Sikkim Himalaya, lithosphere.
Microplastic in the marine nearshore waters of South Georgia: a source to sink approach 
Authors: Buckingham Jack , Waller Cath , Manno Clara , Waluda Claire , Parsons Daniel
Published: March 2022

The polar plastics research community have recommended the spatial coverage of microplastic investigations in Antarctica and the Southern Ocean be increased, and that focus is given to areas with likely microplastic and zooplankton presence and overlap, such as South Georgia. Presented here is a baseline estimate of microplastics in the nearshore, marine waters of South Georgia, the first systematic study of the north-east coast of the island. We estimate the mean concentration of microplastics in seawater to be 2.39 ± 3.58/L (± SD), approximately one order of magnitude higher than the majority of other studies of sea surface waters south of the Polar Front. The maximum concentration of microplastics in wastewater from King Edward Point research station was 1.44 ± 4.93/L (mean ± SD). Following FT-IR polymer analysis and categorisation of microplastics solely by material, multivariate analysis revealed a 22% similarity in the microplastic profiles of wastewater and the seawater it enters. We hypothesise that microplastic pollution from the research base constitutes a fraction of the input into the local marine environment. To explain the observed discrepancy, we hypothesise alternative sources of contamination to be microplastic transported from afar, microplastic from ships (estimated to be up to 36.8 million synthetic fibres per year) and precipitation based on the concentration of microplastic in a single snow sample (15.89 ± 23.72/L, mean ± SD). There was no significant difference in the microplastic concentration between seawater sites, and no significant bilateral relationship between concentration and distance from the research station outlet, however we recommend further finescale mapping of the nearshore hydrological regime to develop a holistic picture of microplastic dispersal and retention at the coast. 

South Georgia is a biodiversity hotspot to which the potential hazard of microplastic pollution is relatively unknown. This research is part of a wider project examining the ecological fate of microplastics in the marine nearshore waters of South Georgia using a source to sink approach. Additional research currently producing preliminary results includes determining the level of microplastic ingestion by keystone plankton and economically important fish species, as well as assessing the potential for trophic transfer of microplastics to higher predators in the region.
Geodetic SAR – the use of electronic corner reflectors in Wladyslawowo and Leba, Poland
Authors: Kur Tomasz , Zdunek Ryszard , Nastula Jolanta , Gisinger Christoph , Śliwińska Justyna
Published: March 2022

We present results for geodetic SAR which is a technique in the field of geodesy and remote sensing that enables the localization of specifically designed radar targets. It might help to connect the GNSS network to tide gauge stations and then to link the sea level records of tide gauge stations to the geometric network. In further perspective it will also enable the determination of vertical movements of the Earth's crust at these stations, allowing the estimation of the absolute value of sea level changes in various regions of the world, which are important in the study of climate change. In order to investigate the feasibility of using active SAR transponders ESA Project Baltic+ Theme No. 5. ‘Geodetic SAR for Baltic Height System Unification and Baltic Sea Level Research (SAR-HSU)’ was completed in 2019 – 2021 by international consortium. During the project SAR novel active transponders were located around the Baltic Sea. Among the locations, two transponders were placed in Wladyslawowo and Leba, Poland under the care of the Space Research Centre of the Polish Academy of Sciences (SRC PAS).

The installation of permanent radar targets allows for long-term position monitoring. The technique is a particularly interesting for displacement and height changes observations. The research illustrates the results acquired from the electronic corner reflectors operating in Poland. For purpose of this research SAR images captured by the Sentinel-1 are used as ESA offers unrestricted access to all the data acquired at study region. Level 1 SLC products together with geodetic data are the main input for the study. With a repeat cycle of 6 days, the number of Sentinel-1 SAR observations per test site amounts to about 180 measurements for one year.

We present the outcomes of ECR positioning from July 2021 to January 2022 when further tests of active transponders were conducted beyond the end of the project. The research is carried out with the software developed in SRC PAS and designed for purposes of geodetic SAR. Software consists of several modules e.g. for data preparation (including SAR data, EOP, precise orbits, ionosphere and troposphere models) or for processing data related to geodynamic effects and corrections to radar measurements. Here we present results for Absolute Location Error in the azimuth and range. We show our experience in processing data for active transponders and our comments on their maintenance and exploitation.
AMOC response to Perturbations in Wind and Buoyancy Forcing in the Subpolar North Atlantic
Authors: Markina Margarita , Johnson Helen , Marshall David
Published: March 2022

Atlantic Meridional Overturning Circulation (AMOC) is an important component of climate system and understanding what governs its variability is essential for improving climate predictability. Recent observational studies show large variability of overturning circulation in the subpolar latitudes with the dominant role of the eastern subpolar gyre, while the role of the wind and buoyancy forcing over the different regions remains underpinned. In this work, we use high-resolution (1/12°) targeted sensitivity experiments with the regional configuration of MITgcm for the North Atlantic. We show that our control experiment with repeated year forcing represents the major oceanic circulation patterns reasonably well and demonstrates similar strength of overturning with observational data from the OSNAP program. We investigate the oceanic response to changes in atmospheric forcing by setting the perturbations in surface momentum and buoyancy fluxes corresponding to the strong positive and negative phases of North Atlantic Oscillation.
Investigating the impact of temporal resolution on a snow model used for hydrological modelling
Authors: Véron Anne-Lise , Tilmant François , Thirel Guillaume , Bourgin François , Perrin Charles , Zuber Félicien
Published: March 2022

Real-time flood forecasting and other hydrological applications in mountainous areas require a good understanding and accounting of snow accumulation and melt. The CemaNeige snow model is currently used with the GRP hydrological model by most regional operational services in France to produce floods forecasts with lead times varying from a few hours to a few days. The snow model is based on a degree-day approach and needs limited inputs (precipitation and air temperature) spatialized on altitude bands over the catchment. It was initially developed on snow-dominated catchments by Valéry et al. (2014) using only streamflow series as calibration information. The model was then adapted by Riboust et al. (2019) to better simulate snow-covered areas as estimated by MODIS satellite images. These data were used as a secondary source of information for parameter calibration. All these developments were made at the daily time step. However, for real-time purposes, the outputs from the snow model are often needed at a finer time step, typically hourly or sub-hourly.

Here the transposability and the consistency of the CemaNeige model were studied across a range of time steps, from hourly to daily, on a set of snow-influenced catchments. This follows previous works on the hydrological model to improve its consistency across time scales (see e.g. Viatgé et al., 2019). Several questions were addressed:

To which extent are the outputs of the snow model and its parameters consistent across various time steps?

Is the current snow model complexity (structure and parameters) sufficient to simulate the snow influence at the catchment scale at sub-daily time steps?

Can we expect better results by running the snow model at sub-daily time steps than by disaggregating the outputs of the snow model run at the daily time?

The answers to these questions will be presented based on a comprehensive testing scheme and a set of numerical criteria. Perspectives in terms of operational use will be discussed.
Harmonic-induced wave breaking due to abrupt depth transitions
Authors: Draycott Samuel , Li Yan , Stansby Peter , Adcock Thomas , van den Bremer Ton
Published: March 2022

Abrupt depth transitions (ADTs) exist in the form of natural and man-made bathymetric features, such as seamounts, continental shelves, steep beaches, reefs, and breakwaters. ADTs have been shown to induce the release of bound waves into free waves, which results in spatially inhomogeneous wave fields atop ADTs and regions where rogue waves are significantly more likely than predicted by linear theory.  Herein, we examine the role of free-wave release in the generation and spatial distribution of higher-harmonic wave components and in the onset of wave breaking for very steep periodic waves upon interaction with an ADT. We utilise a Smoothed Particle Hydrodynamics (SPH) model, making use of its ability to automatically capture breaking and overturning surfaces. We validate the model against experiments. The SPH model is found to accurately reproduce the phase-resolved harmonic components up to the sixth harmonic, particularly in the vicinity of the ADT. For the cases studied, we conclude that second-order free waves released at the ADT, and their interaction with the linear and second-order bound waves (beating), drive higher-order bound-wave components, which show spatial variation in amplitude as a result.  For wave amplitudes smaller than the breaking threshold, this second-order beating phenomenon can be used to predict the locations where peak values of surface elevation are located, whilst also predicting the breaking location for wave amplitudes at the breaking threshold.  Beyond this threshold, the contributions of the second-order and higher harmonics (second–harmonic amplitudes are up to 60% and sixth-harmonic up to 10% of the incident amplitude) cause breaking to occur nearer to the ADT, and hence the wave breaking onset location is confined to the region between the ADT and the first anti-node location of the second-order components.  Counter-intuitively, we find that, at the point of breaking, steeper incident waves are found to display reduced non-linearity as a result of breaking nearer to the ADT.
TomOpt: Differentiable Muon-Tomography Optimization
Authors: Lagrange Maxime , Dorigo Tommaso , Strong Giles , Giammanco Andrea , Vischia Pietro , Fanzago Federica , Nardi Federico , Lamparth Max
Published: March 2022

 

We propose to employ differentiable programming techniques in order to construct a modular pipeline that models all the aspects of a muon tomography task, from the generation and interaction of cosmic ray muons with a parameterized detector and passive material, to the inference on the atomic number of the passive volume.

This enables the optimization of the detector parameters via gradient descent, to suggest optimal detector configurations, geometries, and specifications, subject to external constraints such as cost, detector size, and exposure time.

The eventual aim is to release the package open-source, to be used to guide the design of futur detectors for muon scattering and absorption imaging.
Temporal merging of decadal predictions and climate projections to obtain seamless information: challenges and potential solutions
Authors: Befort Daniel J. , Brunner Lukas , Borchert Leonard F. , O'Reilly Christopher H. , Weisheimer Antje
Published: March 2022

There is an increasing demand from society and policy makers for reliable, robust and actionable climate information for the upcoming 40 years. However, providing such seamless information poses a challenge to the scientific community. Traditionally, the scientific community developed targeted forecasts for specific time scales, e.g. short-term, seasonal or decadal predictions. These model integrations have thus a limited forecast period and do not provide seamless information on time scales up to 40 years.

This work discusses two alternative approaches to combine information from initialized decadal predictions (providing information up to ten years) with uninitialized climate projections (available until 2100 and beyond). 

The first is  a novel framework, which is designed to implicitly make use of the (added) values from initialization by constraining uninitialized climate projections using decadal predictions. This approach is applied to near-surface temperatures over the North Atlantic Subpolar gyre region from CMIP5 models. Results suggest that such a constraining approach is able to provide more skillful, seamless climate information beyond decadal time-scales compared to using unconstrained climate projections. 

The second approach is based on the simple temporal concatenation of decadal predictions and climate projections. It is shown that this can introduce inconsistencies, which may impact the usability for potential end users. Two different methods to overcome these issues are discussed: the application of a simple calibration method and a weighting scheme based on model performance. Results for the calibration method are in general promising, whereas the impact of the model weighting scheme is smaller. The latter is mainly associated with the small size of the decadal prediction ensemble, which hinders the usual application of the weighting scheme as done in previous studies based on much larger ensembles.
In-situ evaluation of sponge-city-type sites for urban trees to tackle flooding and heat islands 
Authors: Zeiser Anna , Murer Erwin , Strauss Peter , Zimmermann Daniel , Weninger Thomas
Published: March 2022

Trees in urban environment face plenty of problems that hamper vital and long-standing growth, which would be essential to counteract urban heat island effect. The major issue is a tremendously reduced volume of appropriate rooting space due to impervious surface and highly condensed underground in the immediate surrounding. Sponge city substrate based on the model of Stockholm promises to provide conditions suitable for root growth even underneath sealed surfaces. This innovative type of substructure construction method consists of unconsolidated fine substrate flushed into the voids of edged stones that serve as load-bearing structure. If well-designed in a function-oriented manner, the volume of sponge city substrate is able to serve as an underground retention basin saving soil water for transpiration and enabling excess water to infiltrate further into the groundwater. To support the creation of such highly functional substrate-pore systems, knowledge about the effects of different materials and methods on the hydrological functions is needed.

In Austria several projects using sponge city for urban tree planting have been implemented in recent years in various cities and municipalities. In order to increase the understanding of the system in hydrological, soil physical and implementational terms and to enable improvements and identification of reasons for malfunction, research is performed at laboratory, lysimeter and field scale. The latest monitoring project has been built in a small street in Graz, where both sides next to the street have been excavated and rebuilt with sponge city substrate. Two different substrate types have been used and 9 trees have been newly planted. The closest monitored part consists of about 100 m³ sponge city substrate, 4 trees and various types of surface design and usage including parking space, perennial plantings and a seepage basin with topsoil passage for purification of street water. Sensors measuring matric potential, volumetric water content, electrical conductivity, soil temperature, sap flow and water inflow from roof and street deliver the basic data to calculate the full water balance within this area and set up a water balance model offering the opportunity to assess the impact and potentialities of sponge city substrate in various temporal and spatial scenarios.

Coupling data from sponge city lysimeters, laboratory experiments and other field monitoring sites an estimation of ecosystem services accomplished by this innovative construction type will be attempted. Focus will be put on retention behaviour for heavy rainfall, plant water availability as well as tree vitality, growth and transpiration.
How the cusp features  and the Alfven Transition Layer are affected by  the IMF Rotation from North to dawn-dusk  direction ?
Authors: Cai Dongsheng , Lembege Bertrand
Published: March 2022

Large-scale global three-dimensional PIC simulations are used in order to analyze the dynamics of the cusp boundaries and particle fluxes penetrating the cusp as the interplanetary magnetic field (IMF) rotates from northward to dawn-dusk direction. Recent 3D simulation works have been previously focussed on the formation of so called Alfven Transition Layer (ATL) located at the upper edge of the Stagnant Exterior Cusp (SEC) as evidenced originally in CLUSTER data (Lavraud et al., 2005) and on 3D dynamics of  electron / ion fluxes penetrating the cusp (Cai et al., 2015; Lembege et al., 2022), but  have been restricted to the northward direction of the IMF. The ATL is defined as a transition layer through which the plasma flow changes its bulk velocity from super-Alfenic regime (in the magnetosheath) to a sub-Alfvenic regime (in the ESC). The present work is an extension of these previous works and is focussed on the impact of the IMF rotation: (i) on the formation and the structure of the cusp itself, (iii) on the size, the location and the 3D features of the ATL, and (iii) on the 3D dynamics of the electron/ion fluxes when penetrating the cusp region. These preliminary results will be compared with those already obtained for a northward IMF. 
Gas Flares of the Norwegian Arctic - Sources and distribution: A comprehensive mapping using MAREANO multibeam data
Authors: Chand Shyam , Thorsnes Terje , Bellec Valérie , Bjarnadóttir Lilja Rún
Published: March 2022

Gas flares from natural sources of hydrocarbon gases escaping through the seafloor to the water column is a phenomenon observed in many parts of the World’s Oceans. The occurrence of these acoustically and visually observed seepages have been recorded by using various sensors onboard different platforms. But the use of multibeam echosounder systems, with the capability of recording the whole water column acoustic backscattering, in recent years have given the opportunity to cover large areas in a short time span along with bathymetric mapping in a cost-effective way. Even though the data sizes are multiple orders of magnitude larger, the use of dedicated software’s and high-performance processing systems have given the opportunity to find acoustic anomalies resulting from the streaming of gas bubbles in water column.

The MAREANO programme which is aimed at mapping habitats through various methods has surveyed large areas of the Norwegian Arctic using multibeam systems. This has resulted in the acquisition of water column acoustic data covering a large area of Arctic Norway over in the last decade. These data have been interpreted and analysed together with other geological and ancillary data from other sensors such as photo/video observations, backscatter data, etc. leading us to relate these anomalies to various structural and geological formations. The database also gave us an opportunity to compare the differences between some of the multibeam systems in capturing these acoustic anomalies. More than approximately 5000 flares of varying magnitude and sizes were detected based on MAREANO water column data, in an area of about 139000 km2. We present the results from these comprehensive surveys and discuss various possibilities that such a database can provide for present and future understanding in the development of Arctic. 
Trees susceptibility to wind damages: the effect of slope
Authors: Costa Maximiliano , Marchi Luca , Locatelli Tommaso , Lingua Emanuele
Published: March 2022

The interaction of forests and wind disturbances is a topical issue in scientific research, especially considering that the ongoing climate change will lead to a probable increase in the frequency of natural disturbances of high severity (e.g., storms).

The study of wind-tree interaction has led to the development of various models for predicting wind risk damage to forest stands. Of these models, ForestGALES is the most widely adopted across forest species and geographical locations. Initially developed in the UK as a management tool to assess the susceptibility of plantations to windstorm damage, this semi-empirical, process-based wind risk model has since been expanded and used in other contexts, both European and non-European. Recently ForestGALES has been updated and developed in the R framework (fgr package), in order to be easily applicable to different scenarios. However, the original ForestGALES reference database used to derive empirical coefficients of tree anchorage is limited to a relatively flat area and small size trees (Diameter at Breast Height -DBH- less than 30 cm).

In this context, the first objective of this research was to investigate the anchorage of standing trees with large diameters by means of pulling tests. Therefore, 44 spruce trees (Picea abies (L.) Karst.), an important species for alpine silviculture and particularly susceptible to wind damage, were subjected to destructive pulling tests.

 Using a load cell, inclinometers and strain gauges the tree felling was monitored in all its phases. Of the 44 plants tested (DBH> 40 cm), 13 were selected in sloped terrain in order to test if slope may affect stability, in a comparison with trees with similar characteristics on flat terrain. The first results showed that trees on a slope have a higher overturning coefficient and are therefore more resistant to uprooting.

The data obtained from the field were translated into input parameters for ForestGALES model, allowing to differentiate the parameters for spruce according to the slope of the terrain. The parametrisation was further complemented with physical parameters (MOE and MOR) typical of spruce trees grown in the mountain/dolomitic environment. Using these new parametrisations, wind risk assessment maps were created for a case study area located in the north-eastern Italian Alps. This area was strongly affected by storm Vaia in October 2018, the mapping, therefore, aims to observe the susceptibility of stands before and after the disturbance event.
The seismic footprint of the devastating July 2021 Ahr Valley flood, Germany
Authors: Dietze Michael , Bell Rainer , Hoffmann Thomas , Schrott Lothar
Published: March 2022

Valley confined floods are a major hazard. In contrast to large river floods with day long warning time, they can evolve within minutes to hours, exhibit higher flow velocities and drive large amounts of debris into populated places. While many Alpine communities have developed mitigation, early warning and rapid response schemes for this natural hazard type, these measures are virtually unknown in Central European upland regions. Beyond flood protection, lacking measurement infrastructure also prevents retrospective collection of event anatomy data, which would be key to understand the evolution of an event and, hence to improve our response to future hazards.

The 14–15 July 2021 flood that hit the Ahr valley in the Eifel mountains, west Germany, was a drastic example of the potential of such valley confined floods. A wall of water flushed through the deeply incised valley, flooding more than 15 towns and affecting 42,000 people, resulting in the highest number of casualties in Germany since 1962. All gauges along the main channel were destroyed while the flood hydrograph was still on the rising limb and grid power loss interrupted collection and transmission of data from other potential sensors.

Here, we use data from a single seismic station near the town of Ahrweiler, originally deployed for earthquake seismology. Despite grid power cutoff around 23:19 CEST, the station recorded the arrival of the fast rising limb of the flood. We show how even an incomplete record of a single station not set up for flood early warning can be used to infer crucial and timely information about the flood: propagation velocity, water level and debris transport rate. We argue that installing a network of a few distributed low cost seismic sensors could have improved flood early warning and near real time provision of kinetic flood data. More importantly, such a network would be the key for improved response actions for future floods, deemed more likely in Central Europe under the currently changing climate conditions.