bluuebunny/crossref_metadata_2025 huggingface dataset:
Deep Learning Strategies for Target Classification via Tomographic Ground Penetrating Radar
Authors: Ambrosanio Michele , Franceschini Stefano , Autorino Maria Maddalena , Pascazio Vito
Published: March 2022

Subsurface and underground exploration and monitoring are of interest for several applications which span from geoscience and archaeology to security and safety areas [1, 2]. In the framework of non-destructive testing, ground penetrating radar (GPR) represents a valuable technology that has been extensively exploited for the detection and characterization of buried objects. Nevertheless, this remote sensing modality has some limitations related to the generated output, since these images of the underground require an expert user for their interpretation. Moreover, identifying and characterizing buried objects still represent a non-trivial task [3].

To this aim, several algorithms have been developed to face the aforementioned issues efficiently and automatically. In this context, approaches based on deep learning and convolutional neural networks (CNNs) have been proposed in the past years and recently gained a lot of attention by the scientific community [4]. Despite their efficiency, these approaches require many cases to perform the training step and improve their classification performance.

In this abstract, the case of a multistatic GPR system is considered via two-dimensional numerical simulations to classify the kind of underground utility automatically in areas in which both water and natural gas pipes can be located. More in detail, some discussions on the classification performance by adopting different topologies and network architectures will be dealt with.

 

[1] Persico, R., 2014. Introduction to ground penetrating radar: inverse scattering and data processing. John Wiley & Sons.

[2] Catapano, I., Gennarelli, G., Ludeno, G. and Soldovieri, F., 2019. Applying ground-penetrating radar and microwave tomography data processing in cultural heritage: State of the art and future trends. IEEE Signal Processing Magazine, 36(4), pp.53-61.

[3] Ambrosanio, M., Bevacqua, M.T., Isernia, T. and Pascazio, V., 2020. Performance Analysis of Tomographic Methods Against Experimental Contactless Multistatic Ground Penetrating Radar. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 14, pp.1171-1183.

[4] Kim, N., Kim, S., An, Y.K. and Lee, J.J., 2019. Triplanar imaging of 3-D GPR data for deep-learning-based underground object detection. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 12(11), pp.4446-4456.
Suspended Particle Characteristics from Glider Observations in a Region of Freshwater Influence
Authors: Bourrin François , Gentil Mathieu , Miles Travis
Published: March 2022

The Rhone River is one of the largest rivers in the North-West Mediterranean Sea. Freshwater and particle (sediments, nutrients and contaminants) inputs make the adjacent coastal area as a remarkable ROFI known as a hotspot of biodiversity in the Gulf of Lions. The dynamics and behavior of riverine particles is often observed from classical moorings, buoys as well as remote sensing. These observing systems only permit limited measurements in 1D for single-point observations in the water column and at the water surface during cloud-free days from remote sensing data. But there is a lack of spatio-temporal observations especially during extreme events when sea campaign investigations are difficult. An autonomous underwater vehicle, also named glider, equipped with a Laser In-Situ Scattering and Transmissometry (LISST) sensor was deployed in front of the Rhone River in February 2019 in order to investigate the small-scale characteristics of particles in the coastal area. In-situ particle size measurements and volume concentrations of suspended particles were related to mass concentrations in order to estimate the density and settling velocity. Results revealed the presence of highly dynamic surface, intermediate and bottom nepheloid layers composed of particles with distinct characteristics. Those results give useful informations to undestand the behavior of particles in the coastal area and for amelioration of regional hydro-sedimentary models.
Triassic-Jurassic tectonic evolution of the Baltic sector of the North German Basin: regional extension, salt movement and large-scale uplift
Authors: Ahlrichs Niklas , Noack Vera , Seidel Elisabeth , Hübscher Christian
Published: March 2022

As a part of the intracontinental Central European Basin System, the Baltic sector of the North German Basin has a long and complex history of basin evolution strongly influenced by salt tectonics. In the scope of the DFG project StrucFlow, we investigate the Triassic – Jurassic phase of basin evolution of the Baltic sector of the North German Basin to deepen the understanding of regional tectonics and their relation to the initial development of Zechstein salt structures. We use a dense network of modern marine high-resolution 2D seismic profiles together with older seismic data and both onshore and offshore wells. Thereby, we strive for a detailed regional tectono-stratigraphic interpretation of Triassic and Jurassic deposits with improved stratigraphic subdivision. We interpret local thickness variations across salt structures, imaged by the seismic data, to identify phases of salt withdrawal in rim-synclines and accumulation within the salt structure. Our analysis covers the northernmost part of both the eastern Glückstadt Graben and the Eastholstein Mecklenburg Block as well as the northeastern basin margin close to Rügen Island. Relatively quiet tectonic conditions characterized by thermal subsidence during the Early and Middle Triassic persisted in the study area. In the Late Triassic, during deposition of the Keuper, Paleozoic faults were reactivated at the northeastern basin margin, which created a local depocenter with increased thickness of Keuper and Lower Jurassic deposits. We interpret this zone with increased Triassic – Jurassic sedimentary thickness as a transtensional graben system connected to deeper Paleozoic structures. Local thickness variations of Triassic units across salt structures and crestal faulting indicate initial salt movement in the eastern Glückstadt Graben and at the Kegnaes Diapir contemporaneous with the onset of Late Triassic regional extension and faulting at the northeastern basin margin. Salt movement continued at least until the early Jurassic. During the Triassic, the Eastholstein Mecklenburg Block formed a more stable area at the transition between the Glückstadt Graben and the fault systems of the northeastern basin margin. Within the Eastholstein Mecklenburg Block, salt movement started only in the latest Triassic and was of decreased intensity. From Middle Jurassic times until the Albian, the North Sea doming event subjected the study area to uplift and erosion, which removed much of the Jurassic and partly Upper Triassic deposits resulting in a study area-wide erosional unconformity.
Assessing, scaling and comparing sap flow, eddy covariance and lysimeter measurements in the BRIDGET toolbox
Authors: Hassler Sibylle K. , Dietrich Peter , Kiese Ralf , Mälicke Mirko , Mauder Matthias , Meyer Jörg , Rebmann Corinna , Strobl Marcus , Zehe Erwin
Published: March 2022

Estimates of evapotranspiration (ET) which can be derived from in-situ measurements are often difficult to compare because they originate from different research disciplines, were collected at different scales using a range of methods, and they entail method-specific uncertainties.

The BRIDGET toolbox – developed within the Digital Earth project – aims to support the harmonisation and scaling of diverse in-situ ET measurements by providing tools for storage, merging and visualisation of multi-scale and multi-sensor ET data. This requires an appropriate metadata description for the various measurements as well as an assessment of method-specific uncertainties.

BRIDGET is implemented both as a standalone Python package and as part of the existing virtual research environment V-FOR-WaTer. It is organised as a toolbox consisting of several sub-sections which deal with the different in-situ measurement methods, their typical scaling approaches and most relevant analysis functions. A corresponding uncertainty framework is developed separately as a Python package and as a tool in V-FOR-WaTer. Our first focus for BRIDGET is upscaling tree-level sap flow measurements and comparing them to respective transpiration estimates from eddy covariance and lysimeters.
Quasi-dynamically downscaled snowpack simulation in Penalara Massif (Sierra de Guadarrama, Central Spain)
Authors: González Cervera Álvaro , Durán Luis
Published: March 2022

The snowpack over mountains represents an important source of water both in these areas and in adjacent lowlands. It also has a large impact on their economy since it affects tourism, communications, logistics and risks associated with its recreational use. Snow cover in mid elevations is experimenting a significant decrease as a consequence of climate change (IPCC-2021) and it is becoming an important issue in the water management agenda. Despite its importance there is a lack of understanding of its dynamics, due to the scarcity of properly distributed temporally and spatially mountain snowpack observations and the availability of specific simulation tools. With the aim of overcoming this scarcity, we present a new processing chain that couples ERA5 atmospheric reanalysis (ECMWF) with the Intermediate Atmospheric Research model (ICAR, from NCAR) and the Flexible Snow Model (FSM2, University of Edinburgh) in order to assess the snowpack in a small area in Penalara Massif, a mountain region in Central Spain. The 2021-2022 winter season have been simulated with a resolution of 2 m for the snowpack output. Several sensitivity experiments have been conducted in order to assess the impact of the uncertainties on the input forcing data. Also, automatic and manual meteorological observations have been used to validate the model and draw future lines of improvement. First results are very promising. This system has been able to explain the main features of the dynamics of the snowpack and future improvements are foreseen like the impact of snow redistribution of fresh snow due to wind drift and a better knowledge of the transformation of the snow pack and melting process.
Rapid changes in return periods of heat-related mortality extremes
Authors: Lüthi Samuel , Fairless Christopher , Fischer Erich M. , Vicedo-Cabrera Ana M. , Bresch David N.
Published: March 2022

The risk of extreme heat mortality is ever increasing with the rapidly changing climate. With the collision of several mega-trends – aging societies, urbanization, inequality – the need for a comprehensive heat mortality risk analysis is growing. Here, we present a probabilistic analysis of the impact of extreme heat on city-scale mortality, demonstrated for more than 750 locations around the world. First results show that heat-related excess mortality of a 100-year summer in the climate of 2000 must be expected roughly every ten to twenty years in today’s climate for most locations.

We produce the probabilistic risk assessment for heat mortality by building on the open-source natural catastrophe risk platform CLIMADA (CLIMate ADAptation). We combine state-of-the-art epidemiological time series analysis methods with single model initial condition large ensemble (SMILE) climate model output. The epidemiological analysis relies on quasi-Poisson regression time series analyses and requires daily city-level mortality data which we have for more than 750 locations through the MCC (Multi-Country Multi-City) Collaborative Research Network database. This analysis results in city-specific risk of exceedance mortality as a function of temperature. The SMILE approach takes a climate model and runs it multiple times with perturbed initial conditions but using the same climate scenario. It thus indicates multiple physically consistent and plausible pathways of the climate which can be used for a probabilistic risk assessment. This allows estimation of tail-risks and quantification of return-period-based mortality impacts. We used SMILE output of seven different climate models, totaling 270 model runs, to estimate impacts and uncertainties of tail risks.

Communicating risk using (shifts in) return periods is helpful to start dialogues with government authorities, city planners and decision makers, as such metrics are commonly used to prepare for natural catastrophes
Increasing topsoil and subsoil organic carbon storage with improved rotation in cropland-grassland agroecosystems
Authors: Guillaume Thomas , Makowski David , Elfouki Saïd , Bragazza Luca , Libohova Zamir , Sinaj Sokrat
Published: March 2022

Soil organic carbon (SOC) accumulation in agroecosystems is a promising solution to simultaneously improve food security and mitigate climate change. Indeed, because of their large carbon deficit, cropland soils can potentially sequester a substantial amount of atmospheric carbon (C). To estimate the soil C-sequestration potential, it is critical to derive reliable estimations of the current soil C-saturation level. This step is essential to obtain an accurate quantification of C-deficits in cultivated soils. In addition, it is important to identify agricultural practices that favor SOC accumulation in order to reduce the soil C-deficit. Based on a 30-year old soil monitoring network of multiple cropland (CR) and permanent grassland (PG) sites established in western Switzerland, we (i) quantified the C-deficit in croplands, (ii) identified the factors driving the C-deficit and (iii) evaluated the assumption that grasslands can be used as C-saturated reference sites. We demonstrated that SOC in CR were depleted by a third compared to PG. The main factor affecting C-deficit in CR was the proportion of temporary grasslands (TG) within the crop rotation. We also showed that PG have not reached their C-saturation level in the study area and that additional C could be stored in PG soil under optimal management. When accounting for pedo-climatic differences, the C-deficit of CR that do not include TG in the rotation was equivalent to 3 kg C m-2 down to 50 cm depth. The relationship between the proportion of TG in the rotation and SOC stocks in the topsoil (0-20 cm) and subsoil (20-50 cm) was linear and similar at both depths, revealing the strong potential of the subsoil to sequester C.
NMR investigation of boundary condition effects on spontaneous imbibitionin Longmaxi shale
Authors: Liu Yong , Yao Yanbin , Liu Dameng , Zhang Chi
Published: March 2022

Spontaneous imbibition is an important process that wetting fluid displaces the non-wetting fluid in the rock by capillary force and is responsible for low flowback efficiency (<30%) of fracturing fluid and severe water blocking effects in shale gas reservoirs. It is crucial to understand the boundary condition effects on imbibition dynamics in shale and the shale-fluid interactions as they provide insights into fracturing fluid loss which can influence gas production. In this study, we designed imbibition experiments and used nuclear magnetic resonance (NMR) to investigate spontaneous imbibition behaviors and water-shale interactions in shale samples with varied boundary conditions including all-side-open (ASO), two-side-open (TSO), one-side-open (OSO), half-side-open (HSO) and two-side-closed (TEC) to. These five boundary effects in imbibition were analyzed by dividing the imbibition stages and comparing the imbibition dynamics. Key imbibition parameters including water saturation, gas recovery factor, residual gas saturation, imbibition capacity, diffusion ability, imbibition rate, and imbibition potential under the respective boundary conditions were selected to compare the imbibition features of five boundary effects. Our results elucidate the existence of three types of water imbibition patterns including the radial counter-current imbibition as shown in TEC boundary condition, the axial co-current imbibition as shown in OSO and TSO conditions, and the compound imbibition which exhibits both radial counter-current imbibition and axial co-current patterns as in ASO and HSO. T2 relaxation times in OSO and TSO shifted to larger relaxation times as imbibition occurred, demonstrating the induced microfractures were generated in water imbibition due to shale-water interactions. Furthermore, imbibition parallel to the bedding plane and imbibition vertical to the beddings have different water migration patterns due to bedding structures of shale. Our experiments contribute to the understanding of the mechanisms of how different boundary conditions affect imbibition dynamics and shale-water interactions in shale gas reservoirs, which is valuable to the interpretation of fracturing liquid retention processes.
Constraining internal surface temperature variability and its implications for detection and attribution
Authors: Schurer Andrew , Luecke Lucie , Hegerl Gabriele
Published: March 2022

The latest generation of climate models (CMIP6) have very different large-scale surface temperature variability and inconsistencies with observed climate have been found in the variability in several regions. Given that detection and attribution, in common with many climate analyses, relies on model internal variability for uncertainty ranges, it is crucial to better constrain this variability. Here, we compare the latest climate models to observed variability to determine where and on what timescales discrepancies occur, with the models found to be, in general, too variable on annual timescales over land and with not as much variability as the observations particularly over the Southern oceans at multi-decadal timescale. We further use paleo-proxy reconstructions, supported by observational datasets finding that the majority of models have variability consistent with large-scale mean temperature on multi-annual and multi-decadal timescales. Finally, the presentation will explore the implications of these findings on key detection and attribution analyses, in particular the attribution of warming since pre-industrial times to anthropogenic forcings.
The poroelastic response of cracked Westerly granite to cyclical changes in load
Authors: Elsigood Bobby , Brantut Nicolas , Meredith Philip , Mitchell Tom , Healy David
Published: March 2022

The poroelastic behaviour of cracked rocks is expected to depend on the geometry and properties of the crack network. Any preferred orientation of microcracks produces anisotropy in physical rock properties, including poroelastic parameters. Under conventional triaxial loading there is an alignment of cracks parallel to the vertical direction of compression, leading to vertical transverse isotropy in the cracked rock.

Here, we repeatedly measured transversely isotropic poroelastic parameters during increasing amplitude cyclic loading in a sample of Westerly granite saturated with water. Independent step changes in confining pressure and differential stress were repeated at selected levels of differential stress to measure the change and reversibility in the transversely isotropic parameters throughout the loading and unloading cycles.

We used miniature differential pressure transducers which were located directly around the sample surface, allowing for direct measurement of the pore pressure in the sample. The direct measurements of pore pressure allow us to estimate undrained properties, including Skempton’s coefficients. Axial and radial strain gauges allow for the calculation of elastic moduli from the step changes in axial and radial stress. We determine the undrained moduli from the initial short-term response, and the drained moduli following pore pressure equilibration for each step change in stress.

Results show that the radial Skempton’s coefficient increases with increased differential stress, and the axial coefficient decreases and even becomes negative (where increases in axial stress cause a decrease in pore pressure) at high stress (i.e., about 80% of failure stress). During unloading, the measured Skempton coefficients are observed to be recovered, without hysteresis.
Assessment of gravity field models derived from Sentinel GPS data
Authors: Grombein Thomas , Lasser Martin , Arnold Daniel , Meyer Ulrich , Jäggi Adrian
Published: March 2022

Besides gravity field information derived from ultra-precise inter-satellite ranging of dedicated missions like GRACE and GRACE-FO, the analysis of GPS tracking data collected by various Low Earth orbiting (LEO) satellites can provide alternative and mostly uninterrupted time series of large-scale time-variable gravity field signals. For this purpose, the GPS data may be used to derive kinematic LEO orbit positions that can subsequently be utilized as pseudo-observations for gravity field recovery.

In this study, we focus on the use of the GPS data obtained by the Copernicus Sentinel-1, -2, and -3 missions. Each of these missions consists of a constellation of two LEO satellites operating on sun-synchronous orbits with inclinations of about 98° and at different altitudes ranging from about 700 to 800 km. Besides mission-specific instruments, the Sentinel satellites are equipped with high-quality dual-frequency GPS receivers providing a data sampling rate of 10s (Sentinel-1, -2) or 1s (Sentinel-3). At the Astronomical Institute of the University of Bern (AIUB), GPS-based precise orbit determination is routinely performed for the Sentinel satellites. We make use of the kinematic LEO orbit positions to perform gravity field recovery with the Celestial Mechanics approach. In the presentation, we will provide details on the quality and sensitivity of Sentinel-based gravity field models and analyze their contribution to a combined gravity field time series derived from Swarm and GRACE-FO GPS data.
Mediterranean coastal sea level reconstruction based on tide gauge observations
Authors: Ramos Alcántara Jorge , Gomis Bosch Damià , Jordà Sánchez Gabriel
Published: March 2022

In order to carry out a proper coastal management it is compulsory to have oceanographic databases that accurately characterize the spatiotemporal variability of sea level along the coast. A first source of sea level observations are tide gauges, which cover different time periods, some of them dating back to the 17th century. Whereas tide gauges generally provide very accurate measurements, their main limitation is that they are point-wise measurements with a heterogeneous spatial distribution and temporal coverage. Therefore, it is difficult to represent the complexity of sea level variability at the coast directly from tide gauge observations. Since 1992, sea level measurements provided by satellite altimetry are also available. This technique has a quasi-global coverage, and by minimising all sources of error affecting the measurements, an accuracy close to 1 cm can be achieved. However, altimetric products have a limited spatial and temporal resolution due to the separation between adjacent satellite ground tracks and to the revisiting time of the satellites. Most important, the accuracy of altimetry observations decreases very rapidly near the coast; despite the advances reached in recent years, standard altimetric data are only available from 5-10 km offshore.

As an alternative to coastal altimetric products, in this work we develop a new methodology to reconstruct coastal sea level from a number of tide gauge observations, which in our case is applied to the western basin of the Mediterranean sea. The reconstruction covers all coastal regions and has the spatial and temporal resolution required to characterise coastal processes. The sea level reconstruction is based on a multiscale optimal interpolation where the spatial correlations between tide gauges and all the coastal points has to be determined prior to the interpolation. In our case, these correlations are computed from the outputs of a high-resolution numerical model. As for observations, for the monthly reconstruction we use PSMSL tide gauge records, which cover the period from 1884 to 2015. For the daily reconstruction we use the series of the GESLA-2 data set, which cover from 1980 to 2015.

A cross-validation test developed to validate the skills of the method shows that our reconstruction clearly outperforms altimetric and modelling products at different time scales, and therefore represents a valuable contribution to the attempts of recovering coastal sea level. Thus, the obtained reconstruction has been used to complement the characterization of open sea level variability in the western Mediterranean previously done by other authors, allowing us to estimate coastal sea level trends, and to examine the correlation between Western Mediterranean coastal sea level and the main North Atlantic climate indices. The limitations and applicability of the method to other regions will also be discussed in the presentation.
Influence of Antarctic Oscillation on the Southeastern Africa summer precipitation during 1979-2018
Authors: Du Chao-jie , Gong Dao-yi
Published: March 2022

In this study, the possible associations between the precipitation in the Southeastern Africa (SEAF, in this study area between 10°S to 25°S and 25°E to 53°E,) and the Antarctic Oscillation (AAO) in seasons from October to March (DJFM) was investigated. A statistically significant three-month lag correlation between them was found. After removing the El Niño/Southern Oscillation and Indian Ocean dipole signals, AAO from August to October (ASO-AAO) and DJFM-precipitation was significantly correlated, and the interannual correlation coefficients calculated by CMAP, GPCP, CRU, and GPCC were +0.63, +0.42, +0.59, and +0.53 (p<0.05), respectively. The positive correlation suggests that an enhancing (weakening) ASO‐AAO could be conducive to increases (decreases) of DJFM-precipitation in SEAF in austral summer. Further analyze the corresponding water vapor and circulation conditions. The responses of local and regional meteorological conditions to the ASO‐AAO support the AAO-precipitation links. During positive ASO-AAO years, in the troposphere low level is a cyclonic flow field in the high level is an anticyclonic circulation, accompanied by an enhanced ascending motion, and such a structure is favor to rainfall. A preliminary mechanism analysis shows that a positive ASO-AAO may induce a sea surface temperature warming tendency in Western Equatorial Indian Ocean.  This warming then enhances the regional ascending motion in SEAF and enhances the convection precipitation on the northwest SEAF. Moreover, the anomalous sensible and latent heating, in turn, intensifies the cyclone through a Gill-type response of the atmosphere. Through this positive feedback, the tropical atmosphere and SST patterns sustain their strength from spring to summer and eventually the SEAF precipitation.Note that’s for simplicity, the AAO index was multiplied by −1 throughout this study.
Towards global dataset of hydro-meteorological and landscape attributes for large-sample hydrological modelling studies
Authors: Abramov Dmitrii , Ayzel Georgy
Published: March 2022

Would the river near my street stay in banks after the forecasted torrential rain? Will the spring flood fill the drinking water reservoirs of big cities? What should we expect from the changing climate? Hydrological modelling studies aim to solve these and other challenging questions providing solutions and guidelines for early warning and hazard risk mitigation. While traditional physically-based hydrological models proved as robust and reliable tools for streamflow prediction for decades, the emerging field of machine learning continues to deliver state-of-the-art modelling solutions in recent years. The power of these data-driven models is built on an explanatory power of underlying data – meteorological forcing and physiographic catchment attributes. While meteorological forcing is globally available and provided by global meteorological reanalysis datasets, catchment attributes datasets are usually region-specific and lacks consistency between different regions. Consequently, that limits the development of global machine learning models for streamflow prediction. Therefore, here we propose a framework for developing a global dataset of hydro-meteorological and landscape attributes that could be utilized for global, large-sample hydrological studies. Our framework is solely based on freely and openly available software and global environmental datasets, making it a reproducible and universal tool that could be further adapted for any region worldwide.
Solute transport in dual conduit structure: effects of aperture and flow rate
Authors: Wang Chaoqi , Majdalani Samer , Guinot Vincent , Jourde Hervé
Published: March 2022

We built 11 lab-scale dual-conduit structures by varying the apertures of the two conduits and we conduct solute transport experiments consisting of step tracing. We investigated how the transport process can be influenced by the following two factors: flow rate and aperture width of both conduits. We found that, as the flow rate increases, the dual-conduit structures more likely presents a breakthrough curve (BTC) with double-peak effect. When the shorter conduit has smaller aperture than the longer conduit, the dual-conduit structure may lead to either single-peaked BTCs or to dual-peaked BTCs with a much lower early peak. When the shorter conduit has larger aperture than the longer conduit, the dual-conduit structure may lead to double-peaked BTCs or to single-peaked BTCs with a bump on the falling limb.

We then compared the ability of three different numerical models in fitting the experimental BTCs: Weighted Sum Advection–Dispersion Equation (WSADE), Mobile Immobile Model (MIM), and Dual Region Mobile Immobile Model (DRMIM). MIM does not reproduce the double-peaked or bump-tailed BTCs, but it captures the overall shape of the experimental curves. The WSADE reproduces some of the double-peaked BTCs except the experiment of 4-6, 200 rpm. The DRMIM exhibits better performance than the other two models, and it captures the observed behaviors of all the experimental BTCs: the second peak, the bump, and the tailing. We finally showed that parameter estimation of the DRMIM model can be improved by restricting the contrast between the parameter pairs: um1 and um2, Dm1 and Dm2, k1 and k2, wm1 and wm2.
Exploring the control of earthworm cast macro- and micro-scale features on soil organic carbon mineralisation across species and ecological categories
Authors: Le Mer Guillaume , Bottinelli Nicolas , Dignac Marie-France , Capowiez Yvan , Jouquet Pascal , Mazurier Arnaud , Baudin François , Caner Laurent , Rumpel Cornelia
Published: March 2022

The role of earthworms on biogeochemical carbon cycling is a major knowledge gap resulting from the difficulty of isolating and exploring the effects provided by the diversity of organisms. In this study, we investigated the effect of six earthworm species belonging to three ecological categories on soil organic carbon (SOC) mineralisation. To this end, we produced casts with the six species using subsoil material with low SOC content and miscanthus litter. Cast were subjected to laboratory ageing for 140 days. During this process, we monitored physicochemical parameters, CO2 emissions and determined the micro-scale organisation of the casts’ particulate organic matter and pores using X-ray tomography.

Our results showed contrasting properties of fresh casts from the 3 main ecological categories, in accordance with the earthworm species’ morphological or behavioral strategies, indicating that those were maintained in artificial environments. However, species-specific changes in cast properties throughout ageing increased intragroup variability among ecological categories. As a result we observed earthworm species-specific evolution of CO2 mineralisation rates during casts ageing. We found that at least half of the variability in CO2 emissions was explained by cast microstructural changes, related to the spatial arrangement between particulate organic matter, porosity, and mineral particles. We conclude that earthworm species-specific traits may play a role in organic carbon protection through their impact on microstructural cast properties.
Comparison of the performance of PCA-NN models for daily mean TEC over the Iberian Peninsula: the role of space weather parameters as predictors for TEC
Authors: Morozova Anna , Barata Teresa , Barlyaeva Tatiana
Published: March 2022

The total electron content (TEC) over the Iberian Peninsula was modeled using a PCA-NN models based on the decomposition of the observed TEC series using the principal component analysis (PCA) and reconstruction of the daily mean TEC and daily PCA modes’ amplitudes by different types of neural networks (NN) using several types of space weather parameters as predictors. Lags of 1 and 2 days between the TEC and space weather parameters are used.

Two main goals are set:

To find a NN configuration(s) that produces forecasts of reasonable quality with minimal amount of input data

To find a best set of space weather parameters that work as predictors for PCA-NN models

Here we present preliminary results related to the second goal: PCA-NN models with different sets of predictors are compared. Among predictors we consider proxies for the solar UV and XR fluxes, number of the solar flares of different types, parameters of the solar wind and of the interplanetary magnetic field, and geomagnetic indices.
The Regional Fractional Energy Balance Equation: Projections to 2100
Authors: Procyk Roman , Lovejoy Shaun
Published: March 2022

We present the fractional energy balance equation (FEBE) which is a generalization of the standard EBE. The FEBE can be derived either from Budyko–Sellers models or phenomenologically by applying the scaling symmetry to energy storage processes. It is easily implemented by changing the integer order of the storage (derivative) term in the EBE to a fractional value near 1/2. 

The model used a Bayesian framework based on historical temperatures and natural and anthropogenic forcing series for parameter estimation. Significantly, the error model was not ad hoc, rather predicted by the model itself: the internal variability response to white noise internal forcing, a fraction Relaxation noise (fRn). Due to computational constraints, we employ a block bootstrapping method to calculate the likelihoods of our parameters in the Bayesian scheme. Notably we estimate the regional relaxation time directly from empirical data, generally it is calculated for various discrete surface types using heat capacities or globally from fitting a two-box model to GCM outputs, which to the authors knowledge has not been estimated prior to this study. 

The FEBE historical reconstructions (1880–2020) closely follow observations (notably during the “slowdown”, 1998–2015). We also reproduce the internal variability with the FEBE and statistically validate this against centennial scale temperature observations. We show the FEBE to plausibly reproduce the annual cycle at monthly resolution, in particular to explain the lag between the temperature maximum and the maximum in the radiative forcing. 

Using the calibrated FEBE we made temperature projections to 2100 using both the Representative Carbon Pathways (RCP) and Shared Socioeconomic Pathways (SSP) scenarios, shown alongside the Coupled Model Intercomparison Project Phase (CMIP) 5 and 6 multi-model ensemble (MME) at global and regional scales.  
A numerical model for microbially mediated soil aggregate formation considering the effect of crop residue quality
Authors: Laub Moritz , Blagodatsky Sergey , Van de Broek Marijn , Schlichenmaier Samuel , Six Johan , Kunlanit Benjapon , Vityakon Patma , Cadisch Georg
Published: March 2022

It is crucial to understand what influences the dynamics of soil aggregates, because soil organic matter (SOM) stabilized inside aggregates is the fraction of SOM that is most susceptible to anthropogenic activity. Yet, there is a lack of numerical process models that include the dynamics of aggregate formation and breakdown and to date, no model represents the important connection between microbial carbon use efficiency (CUE) and aggregate formation. Here, we introduce a model of microbially mediated aggregate formation, which includes litter-stoichiometry and -quality dependent CUE and simulates soil aggregate formation facilitated by the microbial excretion of binding substances. The model is evaluated against measured data of microbial biomass, SOM content and intra-aggregate SOM from a long term bare-fallow experiment in a tropical sandy soil, which was subject to plant litter addition of different qualities. The benefit of simulating aggregates in a model of SOM dynamics is assessed by comparing it against a version that does not, both being separately calibrated to the same dataset. Our results show that the developed model can effectively represent the microbial growth response that follows litter addition and the formation as well as the delayed breakdown of soil aggregates, after the microbial growth peaked. As shown by a higher modelling efficiency and a lower Akaike information criterion, the model version that includes aggregate formation outperforms the one that does not in the simulation of total organic carbon, total N and for the decomposition of litter. Additionally, it can represent the temporal dynamics of C stored in the silt and clay fraction. Yet, while the model could capture the temporal dynamic of aggregates as a result of litter quality, the amount of C in aggregates in the control treatment without litter addition was underestimated. Our results suggest that aggregate formation is an important process that could be included into SOM models to improve the simulation of both aggregated and non-aggregate pools. However, the underestimation of aggregate C in the control could be a hint, that abiotic aggregate formation may be a relevant factor, especially in low input systems, and may also need to be included.
Sulfur and Hafnium Isotope evidence for Early Horizontal Tectonics in Eoarchean Peridotites
Authors: Lewis Jonathan , Hoffmann J. Elis , Schwarzenbach Esther M. , Strauss Harald , Li Chunhui , Münker Carsten , Rosing Minik T.
Published: March 2022

The origins of Eoarchean peridotites found in the Itsaq Gneiss Complex (IGG) of southern West Greenland represent a crucial record of igneous and geodynamic processes on the early Earth. The igneous and geodynamic origins of these rocks have, however, been the subject of controversy, with some researchers arguing that they represent the first known slivers of mantle emplaced by tectonic processes in the crust and others contending that they represent cumulates associated with the local basalt units. The geodynamic context for the formation of these rocks has also been disputed, with some researchers arguing that they formed in a horizontal tectonic setting analogous to a modern subduction zone, while others propose a vertical tectonic origin for all Eoarchean rocks. Here, we provide new insights into the history of these peridotites using multiple sulfur isotope signatures combined with Hf isotope compositions. Anomalously high εΗf values in some IGC peridotites identified in previous studies [1], as well as in metabasalts with boninite-like compositions [2] found in the Isua Supracrustal Belt (ISB) within the IGC, point to contributions from a mantle source already depleted in the Hadean [2]. The multiple sulfur isotope data of the IGC peridotites found south of the ISB reveal small but significant Δ33S anomalies, consistent with incorporation of surface-derived material of Archean age or older. Furthermore, correlations between sulfur isotope data and major and trace element abundances as well as initial Hf isotope values of IGC peridotites support the hypothesis that high-degree melt depletion occurred under hydrous conditions, followed by variable degrees of melt metasomatism. The involved fluid and melt components precipitated sulfides that incorporated surface-derived sulfur with different depositional origins. We propose that these findings are best explained by a horizontal tectonic regime similar to modern arc settings.

 

1. van de Löcht, J., et al., Preservation of Eoarchean mantle processes in ∼3.8 Ga peridotite enclaves in the Itsaq Gneiss Complex, southern West Greenland. Geochimica et Cosmochimica Acta, 2020. 280: p. 1-25.

2. Hoffmann, J.E., et al., Highly depleted Hadean mantle reservoirs in the sources of early Archean arc-like rocks, Isua supracrustal belt, southern West Greenland. Geochimica et Cosmochimica Acta, 2010. 74(24): p. 7236-7260.
Recovery of compacted subsoil : introducing the ROCSUB project
Authors: Johannes Alice , Fontana Mario , Köstel Johannes , Keller Thomas , Weisskopf Peter , Bragazza Luca
Published: March 2022

Severe subsoil compaction can occur during construction due to heavy construction machinery or storage of excavation material. This has consequences on many soil functions such as water storage and purification capacity, water and nutrient uptake by plants, etc. The consequences of subsoil compaction are known but the means and time for recovery are not well documented. Subsoil recovery is sometimes even considered unreachable at human scale.

The aim of the ROCSUB project (Restoration Of Compacted SUBsoil) is to monitor the effects of subsoil compaction on the long term and evaluate the potential of two different restoration methods (mechanical and biological) and the time needed for recovery.

The experiment started in 2020 and takes place on a field in western Switzerland with loamy texture. The subsoil was severely compacted by a heavy pile of excavation material. Compaction occurred directly on the subsoil, after topsoil removal. Visible signs of compaction were detected up to 70 cm depth.

The experiment is designed along three mechanical axes (compacted, mechanically loosened, control) and three vegetal axes (permanent grass, crop, willow trees) with four replication of each combination, resulting in 36 plots. The mechanical loosening was performed with an excavator and willow trees were selected as the most promising bioengineering method for restoring the subsoil structure.

Following properties are monitored or sampled on a yearly basis: soil moisture via TDR probe, yield, plant biomass and physiology, soil structure properties including bulk density, air capacity, water holding capacity, air permeability. The soil structure evolution is also assessed via X-ray computed tomography.

Preliminary results show an improvement in plant biomass (grass and willow) after mechanical loosening treatment. We expect plants of the compacted plots to suffer most during extreme weather conditions (dry or wet). The mechanically loosened treatment is expected to recover drainage function rapidly while water holding capacity should take more time. The combination of mechanical loosening and willow tree is expected to recover most subsoil functions fastest.
The role of baroclinic activity in shaping Earth's albedo in present and future climates
Authors: Hadas Or , Blanco Joaquin , Datseris George , Bony Sandrine , Stevens Bjorn , Caballero Rodrigo , Kaspi Yohai
Published: March 2022

Atmospheric albedo is one of the most influential properties of Earth's climate. Specifically, the midlatitude planetary albedo plays a vital role in shaping the Earth's albedo. Although, there is no one theory to connect midlatitude atmospheric albedo to the midlatitude climate. This study investigates the connection between baroclinic activity, which dominates the midlatitude climate, and cloud cover. We show that EKE and atmospheric albedo are highly correlated on the climatological level. Then, we show that, from a Lagrangian perspective, the positive correlation translates into a high correlation between cyclone and anticyclone strength and cloud cover at all levels. Observing the strength-cloud cover relation across various systems strengths, we see that this coupling is robust and saturates for intense cyclones. Using these insights, we reflect on two aspects of the Earth radiation budget: the Earth hemispheric symmetry in planetary albedo and future changes in Earth atmospheric albedo. Observing the relationship between the storms, mean cloudiness, strength, and spatial distribution, we find that the difference in eddy population between hemispheres can explain the difference in cloud-cover, which counter-balance the higher surface albedo at the NH. Finally, we use the relation between baroclinic activity and midlatitude cloudiness to understand the projected change in cloud patterns in a warmer climate. We show a high correlation between climatological baroclinic activity response and cloud response. We also suggest that the discrepancy between baroclinic activity and clouds response over the SH is due to the saturating nature of the strength-cloudiness curve.
A conceptual model for the initiation of flank creep at Pacaya Volcano, Guatemala
Authors: Gonzalez Santana Judit , Wauthier Christelle , Burns Michelle
Published: March 2022

Magma emplacement is a recognized trigger of volcanic flank instability. There is also growing evidence for links between magmatic intrusions and accelerating creep on detachment faults within volcanic edifices. This driver was recently proposed at Pacaya, an active basaltic stratovolcano in Guatemala with evidence for past flank collapse, and magma-driven flank instability during major eruptions in 2010 and 2014. In order to understand the conditions under which flank creep can be initiated, sustained, or halted at active volcanoes, we investigate the links between flank creep and eruptive behavior at Pacaya and devise a conceptual model for the initiation of flank creep. Flank creep is quantified through time-series of surface displacements from 2007 to 2020 using seven Synthetic Aperture Radar datasets, and eruptive behavior is described through volcanic activity reports, ash advisories, thermal anomaly time-series, and lava flow maps. We identify large transient flank instabilities coincident with vigorous eruptions in 2010 and 2014, but not during times of similarly elevated activity in 2007 to 2009 and 2018 to 2020. Slower creep takes place during the relatively quiescent 2010 to 2014 and 2015 to 2018 intervals, following the 2010 and 2014 transient instability events. Our analysis suggests that during times of elevated volcanic unrest with persistent thermal anomalies and degassing, attributed to open-vent volcanism, as in 2007 to 2009 and 2018 to 2020, magma movements in an open conduit happen with little associated deformation and flank motion. Conversely, whenever new vents open outside the summit area, irrespective of whether this takes place at the start or during a transition in an eruption, transient flank creep can be initiated, as in 2010 and 2014. Therefore, the opening of new vents away from the main summit cone at Pacaya, especially in a north-northwest to south-southeast alignment, could forewarn an increased likelihood of new or accelerating flank creep.