bluuebunny/crossref_metadata_2025 huggingface dataset:
Intra-domain and cross-domain transfer learning for time series
Authors: Otović Erik , Njirjak Marko , Jozinović Dario , Mauša Goran , Michelini Alberto , Štajduhar Ivan
Published: March 2021

In this study, we compared the performance of machine learning models trained using transfer learning and those that were trained from scratch - on time series data. Four machine learning models were used for the experiment. Two models were taken from the field of seismology, and the other two are general-purpose models for working with time series data. The accuracy of selected models was systematically observed and analyzed when switching within the same domain of application (seismology), as well as between mutually different domains of application (seismology, speech, medicine, finance). In seismology, we used two databases of local earthquakes (one in counts, and the other with the instrument response removed) and a database of global earthquakes for predicting earthquake magnitude; other datasets targeted classifying spoken words (speech), predicting stock prices (finance) and classifying muscle movement from EMG signals (medicine).
In practice, it is very demanding and sometimes impossible to collect datasets of tagged data large enough to successfully train a machine learning model. Therefore, in our experiment, we use reduced data sets of 1,500 and 9,000 data instances to mimic such conditions. Using the same scaled-down datasets, we trained two sets of machine learning models: those that used transfer learning for training and those that were trained from scratch. We compared the performances between pairs of models in order to draw conclusions about the utility of transfer learning. In order to confirm the validity of the obtained results, we repeated the experiments several times and applied statistical tests to confirm the significance of the results. The study shows when, within the set experimental framework, the transfer of knowledge brought improvements in terms of model accuracy and in terms of model convergence rate.

Our results show that it is possible to achieve better performance and faster convergence by transferring knowledge from the domain of global earthquakes to the domain of local earthquakes; sometimes also vice versa. However, improvements in seismology can sometimes also be achieved by transferring knowledge from medical and audio domains. The results show that the transfer of knowledge between other domains brought even more significant improvements, compared to those within the field of seismology. For example, it has been shown that models in the field of sound recognition have achieved much better performance compared to classical models and that the domain of sound recognition is very compatible with knowledge from other domains. We came to similar conclusions for the domains of medicine and finance. Ultimately, the paper offers suggestions when transfer learning is useful, and the explanations offered can provide a good starting point for knowledge transfer using time series data.
Information on gravitational mass movements obtained from the spectrograms of their seismic signals generated
Authors: Surinach Emma , Flores-Márquez E. Leticia
Published: March 2021

An understanding of the characteristics of a mass movement descending a slope enables us to obtain a better control through models and also to reduce its associated risks. The seismic signals generated by the mass movement are mainly caused by friction of the moving mass on the ground. Most of the studies of the seismic signals use the spectrograms as a complementary information of the signals. Our study seeks to expand the current applications of the spectrograms using the information contained in them. A spectrogram represents the evolution in time of the frequency content of a time series. It can also be read as a 3D representation of amplitude, frequency and time of the seismic signal. The spectrograms of the seismic signals generated by a mass movement that descend a slope and approach a seismic sensor can be divided into sections: SON (Signal ONset), SOV (Signal Over) and SEN (Signal End), depending on whether the gravitational mass movement is approaching the sensor, is on it or is moving away from it.

The method presented here consist of analyzing the spectrogram as an image, applying image processing techniques as “Hough Transform”. This method allows us to obtain quantitative information from the spectrograms. Our aim is to obtain the parameters of the shape of the spectrograms, focused on SON section, to create indicators linked to the evolution of the mass movement, for example the speed. The method is applied to spectrograms of three types of gravitational mass movements: snow avalanches (7), lahars (4), and debris flows (1). The results indicate similarities in the shape of the spectrograms of the different types of mass movement, prevailing, however, the specific characteristics of each type.
Wave-selective beamforming with Distributed Acoustic Sensing
Authors: Bowden Daniel C. , Klaasen Sara , Martin Eileen , Paitz Patrick , Fichtner Andreas
Published: March 2021

As fibre-optic DAS deployments become more common, researchers are turning to tried-and-true methods of locating or characterizing seismic sources such as beamforming. However, the strain measurement from DAS intrinsically carries its own sensitivities to both wave type and polarization (Martin et al. 2018, Paitz 2020 doctoral thesis). Additionally, a measurement along a conventional fibre-optic cable only provides one component of motion, and so certain azimuths may be blind to certain types of seismic sources, unless the cable layout can be designed to be oriented in multiple directions.

In this work, we explore the development and application of a beamforming algorithm that explicitly searches for multiple wavetypes. This builds on 3-component beamforming or Matched Field Processing (MFP) algorithms by Riahi et al. (2013), and Gal et al. (2018), where in addition to gridsearching over possible source azimuths, a distinct gridsearch is performed for each possible wavetype of interest. This does not solve the problem that a given cable orientation might be less sensitive to certain directions, but at least an array-response function can be robustly defined for each type of seismic excitation. This might help further distinguish whether beamforming observations are dominated by primary sources or by secondary scattering (van der Ende and Ampuero, 2020 preprint).

Much of this work uses analytic theory and synthetic examples. Time permitting, the enhanced algorithm will also be applied to data from the Mt. Meager experiment to explore its feasibility and efficacy with real data (EGU contribution from Klaasen et. al, 2021).
Reconstructing intra-annual cropping dynamics on irrigation schemes in data sparse environments by fusing Landsat and MODIS imagery . 
Authors: Higginbottom Tom , Adhikari Roshan , Redicker Sarah , Foster Tim
Published: March 2021

Governments and engineers have promoted the construction of large-scale, formalised, irrigation schemes across Africa for nearly 100 years. These developments are designed to increase food production and reduce the vulnerability of agriculture to climate shocks. Yet over the past decades, many irrigation schemes have deteriorated or completely failed; due to a wide range of problems from faulty infrastructure to unexpectedly severe climate shocks. Understanding the drivers of successes and challenges on irrigation schemes is complicated by limited long-term statistics. Meanwhile, for historic Earth-observation based analysis, the Landsat archive remains poor for large areas of Africa, and MODIS imagery is too coarse for meaningull mapping.

Here, we demonstrate a multi-sensor fusion methodology to map the expansion and intensification dynamics of irrigation schemes in the 21st century. Our methodology produces monthly Landsat-like images from the fusion of Landsat 5, Landsat 7 SLC-off, and MODIS imagery, which are classified into cropped area estimates. First, we use the StarFM fusion algorithm to generate monthly Landsat-like images from MODIS composites, based on temporally co-located MODIS and cloud free Landsat 5 or Landsat 7 SLC-on images. Next, we adjust these Landsat-like images against Landsat 7 SLC-off pixels by iteratively reweighting within a spatiotemporal Generalised Additive Model. Finally, we classify the derived monthly, Landsat-like, time-series data using a Random Forest classification model, mapping the number of crops harvested per year for the 2000-2020 period.

We test this methodology against two irrigation schemes in West Africa: the Office du Niger scheme in Mali and the Bagre Irrigation Scheme in Burkina Faso. For both sites, the mapped areas correlate with official statistics on cropped areas. Our data highlight infrastructure improvement and expansion on the Office du Niger, and the resilience of the scheme to rainfall variability. Whilst on the Bagre scheme, we show a vulnerability to large rainfall deficits, and a recent expansion in cropping frequency on newly developed extensions. This methodology is applicable to many areas where the Landsat archive is limited, but intra-annual mapping is required.
The effect of habitat complexity on microbial processes
Authors: Arellano-Caicedo Carlos , Ohlsson Pelle , Hammer Edith C.
Published: March 2021

The effect of habitat complexity on microbial processes

 

The way microbes behave in nature can vary widely depending on the spatial characteristics they are located in. This aspect of the microbial environment can determine whether processes such as organic matter degradation, nitrogen fixation, or microbial speciation, among others, occur and the extent to which they occur. Investigating how the different spatial characteristics of microhabitats influence microbes has been challenging mainly due to methodological limitations. In the case of soil sciences, attempts to describe the inner structure of the soil pore space, and to connect it to microbial processes, has been one of the main goals of the field in the last years. A major challenge in soil microbial ecology is to reveal the mechanisms that prevent nutrient limited soil microorganisms to access the soil organic matter pools. My project is directed towards answering the question of how spatial complexity affects microbial growth, and how this can lead to organic matter stabilization.

Using microfluidic devices that were designed to mimic the inner soil pore physical complexity, we followed the effect of an increasing complexity in the growth and substrate degradation of bacterial and fungal lab strains. The parameters we used to measure complexity were two: the turning angle and order of pore channels, and the fractal order of a pore maze. When we tested the effect of an increasing in turning angle sharpness on microbial growth, we found that that as angles became sharper, bacterial and fungal growth decreased, but fungi were more affected than bacteria. We also found that the substrate degradation was only affected when bacteria and fungi grew together, being lower as the angles were sharper. This confirms the hypothesis that an increasing angle sharpness in an elongated pore space would decrease organic matter degradation. Our next series of experiments, testing the effect of maze fractal complexity, however, showed a different picture. While the effect of complexity on fungi was negative, similar to the previous experiments, bacteria were positively affected by maze complexity, growing more as mazes increased fractal iterations. Substrate degradation was also higher as mazes were more complex. In this case, the results were contrary to our hypothesis, especially for bacteria. To see the relevance of our results in natural microbial communities, we repeated both experiments on a soil microbial extract (containing mainly bacteria) and followed the substrate degradation patterns over time. We found, in this case, that as complexity increased, both in terms of angle sharpness and fractal order, the substrate consumption also increased. Our results show that the spatial complexity provides microbes an environment for a wide variety of ecological interactions to occur that lead to a higher substrate degradation efficiency.
Forecasting groundwater pumping cap in an overexploited Mediterranean aquifer using seasonal meteorological forecasts from Copernicus Climate Change Service
Authors: Rubio-Martin Adria , Macian-Sorribes Hector , Lopez-Perez Esther , Garcia-Prats Alberto , Manzano-Juarez Juan , Jimenez-Bello Miguel Angel , Pulido-Velazquez Manuel
Published: March 2021

The Requena-Utiel aquifer in the Jucar River Basin (Mediterranean Spain) is mined mainly for the irrigation of vineyards (Denominación de Origen Utiel-Requena), and some olive and nut trees. It has been recently declared as in bad quantitative status by the Jucar River Basin Agency (Confederación Hidrográfica del Júcar, CHJ). Among the measures taken to control water abstraction, a pumping cap for the irrigation season (May-September) has been agreed between the CHJ and the groundwater user association. This limit depends on the cumulative precipitation from December to April (classifying the year in wet, normal or dry), although that irrigation amount is in any case below the crop requirements. Consequently, predicting the type of year beforehand is a piece of valuable information for the water users in order to optimally schedule groundwater pumping and foresee crop production.

This study analyses the ability of seasonal meteorological forecasts from the Copernicus Climate Change Service (C3S) to anticipate the type of year in the agricultural areas of the Requena Utiel aquifer considering different periods ahead. The following seasonal forecasting services were used: ECMWF SEAS5, UKMO GloSEA5, MétéoFrance System, DWD GCFS, and CMCC SPS. Seasonal forecasts issued between November 1st and April 1st were downloaded and post-processed using a month-dependent linear scaling against historical records. Once post-processed, the skill of seasonal forecasts to predict the type of year has been evaluated for the 1995-2015 period, depending on the anticipation time.

Results show that, on a broader view, the type of year cannot be safely anticipated before April 1st. However, we have identified that, for particular types of year and forecasting services, the anticipation time can be enlarged (e.g predicting wet years in December). Furthermore, we have found a direct relationship between the strength of the signal (number of ensemble members that predict the same type of year) and the forecasting skill, meaning that seasonal forecasts showing a strong signal, if properly identified, could offer valuable information months in advance to the beginning of the irrigation season.

Acknowledgements:

This study has received funding from the eGROUNDWATER project (GA n. 1921), part of the PRIMA programme supported by the European Union’s Horizon 2020 research and innovation programme. It has been also supported by the ADAPTAMED project (RTI2018-101483-B-I00), funded by the Ministerio de Economia y Competitividad (MINECO) of Spain and with EU FEDER funds.
Hydro-meteorological data preparation for ecosystem hydrological modelling in the riparian forest of Hidegvíz Valley experimental catchment
Authors: Nevezi Csenge , Bazsó Tamás , Gribovszki Zoltán , Szőke Előd , Kalicz Péter
Published: March 2021

In the Hidegvíz Valley experimental catchment in Hungary the meteorological data have been collected since the 1990s and used for various purposes including hydrological studies. Current research began in 2018–19, that aimed to reveal the connections between the hydrological and botanical characteristics in riparian forests and a wet meadow. Changes that occurred in both ecosystems in the groundwater levels, soil moisture and vegetation, showed that the local meteorological events influence these factors. Therefore we decided to analyse longer periods in which meteorological extremes
strongly influenced hydrological conditions and so status of ecosystems. Further measurements and their analysis were also required because more accuracy and detail were needed for future water balance modelling.

The measured data between 2017–2020 were chosen as a starting database. For the first analysis we selected three meteorological parameters, i. e. the precipitation, the air temperature, and the air humidity. These parameters were measured by automated instruments, except for the precipitation. We found that the automated tipping-bucket rain gauge needs validation by a manual measurement (Hellmann-type rain gauge), because the data that collected by the automated device will be invalid if the rain intensity is too high.

In 2017 and 2018, the annual precipitation was distributed evenly, but in the following two years we observed some extremes. In 2019 and
2020, the spring was especially dry, the lowest monthly sum was 1.2 mm in 2020 April. 2019 April was similar (19.5 mm), but after the drought
period intense rainfall events arrived in May, resulted a monthly total of 214.1 mm. Air temperature and air humidity has not been showed such extremes as the precipitation.

This study showed that detailed analysis of meteorological parameters is crucial for hydrological modelling data preparation because errors and extreme event can cause serious problems during modelling process and, also in case of evaluation of model results.

The research has been supported by the Ministry of Agriculture in Hungary.
Global climate anomalies and their association with the mass balance of the Antarctic Ice Sheet
Authors: Kaitheri Athul , Mémin Anthony , Rémy Frédérique
Published: March 2021

Nominal mass change patterns of the Antarctic Ice Sheet (AIS) are usually altered by climate anomalies. By alternating warm and cold conditions, El Niño Southern Oscillation (ENSO) alters moisture transport, sea surface temperature, precipitation, etc in and around the AIS and potentially produces such anomalies. Indices like the Southern Oscillation Index (SOI) and the Oceanic Niño Index (ONI) robustly represent the ENSO phenomenon and is used to evaluate the characteristics of an El Niño or a La Niña. Very few studies have taken place exploring the influence of climate anomalies on the AIS and only a vague estimate of its impact is available.

Changes to the ice sheet are quantified using observations from space-borne altimetric and gravimetric missions. We use data from missions like Envisat (2002 to 2010) and Gravity Recovery And Climate Experiment (GRACE) (2002 to 2016) to estimate monthly elevation changes and mass changes respectively. Similar estimates of the changes are made using weather variables (surface mass balance (SMB) and temperature) from a regional climate model (RACMO2.3p2) combined with a firn compaction (FC) model. Inter-annual height change patterns are then extracted using empirical mode decomposition and principal component analysis to investigate a possible influence of climate anomalies on the AIS.

Elevation changes estimated from different techniques are in good agreement with each other across AIS especially in West Antarctica, Antarctic Peninsula, and along the coasts of East Antarctica. Investigating the inter-annual signals in these regions revealed a sub-4-year periodic signal in the height change patterns. This periodic behavior in the height change patterns is altered in the Antarctic Pacific (AP) sector possibly by the influence of multiple climate drivers like the Amundsen Sea Low (ASL) and the Southern Annular Mode (SAM). Height change anomaly also appears to traverse eastwards from Coats Land to Pine Island Glacier (PIG) regions passing through Dronning Maud Land (DML)  and Wilkes Land (WL) in 7 to 8 years. This is indicative of climate anomaly traversal due to the Antarctic Circumpolar Wave (ACW). Altogether, variability in the SMB of the AIS is found to be modulated by multiple climate anomalies.
Ship-based aerosol measurements in the Southern Ocean 
Authors: van den Heuvel Floortje , Lachlan-Cope Thomas , Witherstone Jonathan , Hurren Dean , Jones Anna
Published: March 2021

Our limited understanding of clouds is a major source of uncertainty in climate sensitivity and climate model projections. The Southern Ocean is the largest region on Earth where climate models present large biases in short and long wave radiation fluxes which in turn affect the representation of sea surface temperatures, sea ice and ultimately large scale circulation in the Southern Hemisphere. Evidence suggests that the poor representation of mixed phase clouds at the micro- and macro scales is responsible for the model biases in this region. The Southern Ocean Clouds (SOC) project will be a multi-scale, multi-platform approach with the aim of improving understanding of aerosol and cloud microphysics in this region, and their representation in numerical models.

Although this years’ first SOC measurement season has suffered greatly from travel restrictions, we have installed an Optical Particle Counter (OPC) on a ship (The James Clark Ross – JCR) and recorded aerosol measurements as it was travelling through the Atlantic sector of the Southern Ocean towards the Antarctic Peninsula, and while the ship was moored at South Georgia and Port Stanley. Over the course of one month, the OPC recorded particle sizes between 0.35 and 40 micrometers every six seconds. This study will present the data from this first, rather short Antarctic SOC season. It will present the analyses of the obtained OPC data alongside satellite observations and model reanalyses in the same region.
Functionalized nanocelluloses as bio-based chemicals in froth flotation
Authors: Ludovici Feliciana , C.B. de Carvalho Ana Luiza , Hartmann Robert , Liimatainen Henrikki
Published: March 2021

Froth flotation is the most common process in the mining industry for the beneficiation of complex sulfide ores. For this purpose, thiol collectors (mostly xanthates) are typically used as flotation chemicals because of their efficacy. However, concerns for their effect on human health and negative impact on the environment increasingly urge for alternative candidates. Consequently, there are great ecological and economical interests to develop novel green chemicals from renewable resources to overcome the inherent environmental and health problems associated with traditional petroleum-derived mining chemicals. Cellulose, which is the most abundant natural polymer resource, represents a green alternative raw material to develop sustainable chemicals that could replace currently used synthetic additives. In the present work, we introduce a novel environmentally friendly and industrially feasible process to produce selective froth flotation chemicals. Therefore, the pulp fibers were disintegrated to cellulose nanoparticles and further functionalized with a silylation reaction in aqueous conditions. Two different functional groups were incorporated into the cellulose nanoparticles and subsequently investigated, namely a thiol-functional moiety, which has an affinity towards pyrite ore surfaces, or an amine-functional moiety, which has an affinity towards silica surfaces. Microflotation tests were carried out in a Hallimond tube to study the flotability of pure pyrite or quartz as a function of pH value, collector concentration, flotation time, and gas flow rate using the novel green nanoparticles, and their results were compared with commercial xanthate and amine chemicals.

 

Keywords: cellulose nanoparticles, deep-eutectic solvent, silylation, ore beneficiation, froth flotation.
New insights on the Vélodrome syncline in the western sub-alpine foreland basin of Haute Provence : 3-D geometrical modelling approach
Authors: Faure Agathe , Jolivet Laurent , Gumiaux Charles , Allanic Cécile , Laurent Gautier , Loget Nicolas , Callot Jean-Paul , Guiomar Myette
Published: March 2021

In the front of the Digne thrust, the deformed foreland basin, the well exposed tectonic window of Barles, is still not well understood. This region has undergone a complex tectonic history involving synsedimentary deformation, potential migration of alpine front, late exhumation related to surface processes and potential salt tectonics. Although the stratigraphy and the structural geology of the area is well known, the respective contributions of regional tectonics, salt tectonic and surface processes remain uncertain. The region displays still enigmatic objects emplaced at each step, from the rifting phase to the late exhumation, such as the overturned Liassic Barre de Chine or the overturned Miocene syncline of the Vélodrome. This study aims at understanding the evolution of the foreland Valensole basin from the deposition of first sediments 30Ma ago to late exhumation and relief formation. We focused our work on the emblematic Vélodrome syncline which is also the only place where a continuous sequence of the basin deposits is exposed. The molassic and conglomeratic layers of the Vélodrome form an overturned syncline with a curved axis of which direction changes from EW in the north to NS in the most south-eastern part. The Vélodrome has been studied for more than a century but its history is still debated. If the Vélodrome is often interpreted as a growth fold which explain the observation of progressive unconformities, microstructural analyses (Fournier et al., 2008) suggest that folding postdates sedimentation. Moreover, recent studies (Graham et al., 2012) propose that this spectacular fold formed as a result of salt tectonic. The obliquity of the regional shortening direction regarding the axis direction, the 3-D pattern of the overturned Miocene series and the origin of the progressive unconformities are issues still not resolved. Such a complex tectonic structure as the Vélodrome fold requires a thorough understanding of the 3-D geometries and their evolution through time. Based on field observations and 3-D geometrical modelling (GeoModeller - ©BRGM), we propose a preliminary model of the Vélodrome that brings new insights on this part of the Valensole basin. The implicit approach that offer the GeoModeller and the field structural data-based approach (here more than 2000 structural data) bring an objective and new vision of the geometries in 3-D of the Vélodrome basin and provide arguments to determine the contribution of each geological processes in the tectonostratigraphic evolution of the north margin of the Valensole basin and subsequent shortening at the western subalpine front.
Target food security: assimilating ultra-high resolution satellite images into a crop-yield forecasting model
Authors: Ziliani Matteo G. , Aragon Bruno , Franz Trenton , Hoteit Ibrahim , Sheffield Justin , McCabe Matthew F.
Published: March 2021

Assimilating biophysical metrics from remote sensing platforms into crop-yield forecasting models can increase overall model performance. Recent advances in remote sensing technologies provide an unprecedented resource for Earth observation that has both, spatial and temporal resolutions appropriate for precision agriculture applications. Furthermore, computationally efficient assimilation techniques can integrate these new satellite-derived products into modeling frameworks. To date, such modeling approaches work at the regional scale, with comparatively few studies examining the integration of remote sensing and crop-yield modeling at intra-field resolutions. In this study, we investigate the potential of assimilating daily, 3 m satellite-derived leaf area index (LAI) into the Agricultural Production Systems sIMulator (APSIM) for crop yield estimation in a rainfed corn field located in Nebraska. The impact of the number of satellite images and the definition of homogeneous spatial units required to re-initialize input parameters was also evaluated. Results show that the observed spatial variability of LAI within the maize field can effectively drive the crop simulation model and enhance yield forecasting that takes into account intra-field variability. The detection of intra-field biophysical metrics is particularly valuable since it may be employed to infer inefficiency problems at different stages of the season, and hence drive specific and localized management decisions for improving the final crop yield.
Creeping gabbro: dissolution-precipitation creep facilitating deformation in mafic rocks
Authors: Lee Amicia , Stünitz Holger , Soret Mathieu , Battisti Matheus Ariel , Konopásek Jiří
Published: March 2021

Mafic rocks consist of strong minerals (e.g. clinopyroxene, plagioclase) that can only be deformed by crystal plastic mechanisms at high temperatures (>800°C). Yet, mafic rocks do show extensive deformation by non-brittle mechanisms when they have only reached lower temperatures (~650°C). In many of such cases, the deformation is accommodated by an interaction of deformation with simultaneous mineral reactions. Here we show that dissolution-precipitation creep plays a major role in deformation of gabbro lenses at mid and upper amphibolite facies conditions.

The Kågen gabbro in the North Norwegian Caledonides intruded the Vaddas Nappe at 439 Ma at pressures of 7-9 kbar, temperatures of 650-900°C, and depths of ∼26-34 km. The Kågen gabbro on south Arnøya is comprised of undeformed gabbro lenses with sheared margins wrapping around them. This contribution analyses the evolution of the microstructures and metamorphism from the low strain gabbro lenses to high strain mylonites at margins of the lenses. Microstructural and textural data indicate that dissolution-precipitation creep is the dominant deformation mechanism, where dissolution of the gabbro took place in reacting phases of clinopyroxene and plagioclase, and precipitation took place in the form of new minerals: new plagioclase and clinopyroxene, amphibole, and garnet. Amphibole shows a strong CPO that is primarily controlled by its preferential growth in the extension direction. Synchronous deformation and mineral reactions of clinopyroxene suggests mafic rocks can become mechanically weak during the general transformation weakening process, i.e. the interaction of mineral reaction and deformation by diffusion creep. The weakening is directly connected to a fluid-assisted transformation process that facilitates diffusion creep deformation of strong minerals at far lower stresses and temperatures than dislocation creep. Initially strong lithologies can become weak, provided that reactions can proceed during deformation, the transformation process itself is an important weakening mechanism in mafic (and other) rocks, facilitating deformation at low differential stresses.
Common EOFs in atmospheric science and large-scale flow
Authors: Hannachi Abdel , Finke Kathrin , Trendafilov Nickolay
Published: March 2021

Conventional analysis of the large-scale atmospheric variability and teleconnections are obtained using the empirical orthogonal function (EOF) method, which was developed mainly to deal with single fields. With the increase of the amount of observed/simulated large-scale atmospheric data including climate models, e.g., CMIP, there is a need to develop methods with efficient algorithms that enable analysis and comparison/validation of climate model simulations. Here we describe the common EOF method, which finds common patterns of a set of large scale atmospheric fields, and enables comparing several model outputs simultaneously. A step-wise/sequential algorithm is presented, which avoids the difficulty encountered in previous algorithms related to the lack of simultaneous monotonic change of the eigenvalues of all fields. The theory and algorithm are presented, and the application to large-scale teleconnections from various reanalysis products and CMIP6 are discussed.
Optimization of small hydropower systems in water distribution networks through evolutionary algorithms and water demand forecasting
Authors: Sitzenfrei Robert , Schartner Lukas , Oberascher Martin
Published: March 2021

The transition from fossil fuel to renewable energies represents the central challenge of the early 21st century. In this context, small hydro power systems (SHPS) can be implemented in water distribution networks (WDNs) to use pressure and drinking water surplus for hydropower production. However, inflow to SHPS is normally controlled based on the available water volume after ensuring a reliable drinking water supply and considering a fire-fighting reserve. Hence, the hydropower generation in WDNs has to be in accordance with its primary tasks. The challenge now is to optimally use the available pressure and water surplus for hydropower production while at the same time reliably fulfilling drinking water constraints.

In this work, future predictions of daily water demand are added into the control strategy of SHPS to optimize the operation. The control procedure of a SHPS is optimized by means of an evolutionary algorithm in combination with Monte-Carlo sampling. This is done for different categorized water demand and water source data in order to maximize profit while ensuring the WDNs reliable operation. Further, water demand forecasts of varying quality are evaluated in combination with previously optimized and categorized SHPS control-sets. For case study, a real WDN of an Alpine municipality is hypothetically retrofitted with a controllable SHPS. Different types of SHPS and turbine characterises are investigated using amount of hydropower production, more specifically profitability, as performance indicator.

While in literature, optimization is usually performed based on representative days (e.g., average day demand), long-term simulations over 10 years are used in this work. Therefore, a sufficient supply pressure in all water demand nodes in the WDN is ensured during this period. This results in a significant lower but more realistic estimation of potential benefits. The results also show, that after optimizing the SHPS location and device size, an additional potential increase of yearly profit of 1.1% can be achieved in the long-term operation of a Pelton turbine by considering water demand forecasts.
The observation of different aerosols types in the Mount Etna environment and their relative and mutual impacts on local radiative balance
Authors: Sellitto Pasquale , Salerno Giuseppe , Scollo Simona , di Sarra Alcide Giorgio , Boselli Antonella , Leto Giuseppe , Zanmar Sanchez Ricardo , Sannino Alessia , Caltabiano Tommaso , Giammanco Salvatore , Monteleone Francesco , Pace Giandomenico , Giorio Chiara , Crumeyrolle Suzanne , Legras Bernard
Published: March 2021

The EPL-RADIO (Etna Plume Lab - Radioactive Aerosols and other source parameters for better atmospheric Dispersion and Impact estimatiOns) and EPL-REFLECT (near-source estimations of Radiative EFfects of voLcanic aErosols for Climate and air quality sTudies) projects, funded by the EC Horizon2020 ENVRIplus and EUROVOLC Transnational Access to European Observatories programmes, aim to advance the understanding of Mount Etna as a persistent source of atmospheric aerosols and its impact on the  radiative budget at proximal to regional spatial scales. Research was tackled by carrying out three campaigns in the summers of 2016, 2017 and 2019 to observe the volcanic plume produced by passive degassing, proximally and distally from the summit craters, using a wide array of remote sensing and in situ instruments. Diverse data are collected to explore the link of inner degassing mechanisms to the characterisation of near-source aerosol physicochemical properties and subsequent impacts on the atmosphere, environment and regional climate system.

The results of the three campaigns have shown that the volcanic plume emitted by Mount Etna often mixes with aerosols of different origins generating a complex layered pattern. Frequent mineral dust transport events were observed by both LiDAR observations located at Serra La Nave (~7 km south-west from summit craters) and at a medium-term radiometric station, equipped with a Multi-Filter Rotating Shadowband Radiometer (MFRSR), and other instruments located at Milo (~10 km eastwards from the craters). LiDAR observations also allowed to study the coexistence of volcanic aerosols and biomass burning particles from local to more distal smoke plumes transports (like for the well-documented large fires from continental southern Italy in July 2017). In situ filter and optical particles counter measurements confirmed the presence of dust at Milo. The interaction/mixing among volcanic, wildfire, and dust aerosols occurs in an overall dynamical regime which appears to be dominated by sea breeze, which is strengthened by the presence of the dark volcanic lava flanks. Photolysis process also possibly play a role in determining the daily evolution of the aerosol plume.

The sources of these different aerosol types are studied in detail using Lagrangian trajectories and meteorological data. Off-line radiative transfer calculations, using EPL-RADIO/REFLECT observations as input data, are used to estimate the relative radiative impact of the different aerosol types with respect to the background passive-degassing aerosols coming from Mount Etna.
Variability of near-inertial waves in the lower stratosphere from balloon observations and the ECMWF (re)analyses
Authors: Podglajen Aurélien , Plougonven Riwal , Hertzog Albert , Dharmalingam Selvaraj
Published: March 2021

Near-inertial waves (NIWs) with intrinsic frequency close to the local Coriolis parameter f constitute a striking component of the kinetic energy spectrum in both the atmosphere and the ocean. However, contrary to the oceanic case, the strong and variable background atmospheric winds tend to shift the frequency of the waves (Doppler effect). As a consequence, atmospheric NIWs cannot generally be observed directly as a kinetic energy peak at ground-based frequency f but are instead diagnosed indirectly (e.g. using the polarisation and dispersion relations). This complication does not appear when analyzing quasi-lagrangian observations from superpressure balloons (SPB), which drift together with the flow and are thus exempt from Doppler shift. Past SPB observations in the lower stratosphere have revealed the magnitude of the kinetic energy peak associated with NIWs and it was recently shown that state-of-the-art reanalyses partly represent this feature.

In this presentation, we will investigate the variability of NIWs using ECMWF (re)analysis products (the operational analysis and ERA5) and balloon observations from recent CNES campaigns (2005, 2010 and 2019-2020) at various latitudes ranging from the equator to the pole (and hence different inertial frequencies). As in Podglajen et al. (2020), NIWs are extracted from the (re)analyses by computing Lagrangian trajectories using the analyzed wind and temperature fields. We will illustrate the remarkable realism of model NIWs, both statistically and for specific case studies. Then, we will characterize the geographic and seasonal variability of NIW properties. In light of those results, possible factors influencing the near-inertial energy peak (horizontal wave propagation, refraction near critical levels, tide interactions) and the parallel with the oceanic situation will be discussed, as well as the ability of the model and data assimilation system to simulate them.

Reference :

Podglajen, A., Hertzog, A., Plougonven, R., and Legras, B.: Lagrangian gravity wave spectra in the lower stratosphere of current (re)analyses, Atmos. Chem. Phys., 20, 9331–9350, https://doi.org/10.5194/acp-20-9331-2020, 2020.
Bulk rock geochemistry of a swarm of orangeite dykes intersecting the Western Limb of the Bushveld Complex
Authors: Compton-Jones Charlie , Hughes Hannah , McDonald Iain , Bybee Grant , Kinnaird Judith , Andersen Jens
Published: March 2021

The Western Limb of the Bushveld Complex hosts a vast, recently documented swarm of orangeite dykes that are significantly younger (177-132 Ma; Hughes et al., in prep.) than the c. 2.06 Ga Bushveld lithologies they intrude. Orangeite dykes are hybrid igneous rocks that form from very low-degree partial melting deep within the sub-cratonic lithospheric mantle (SCLM) and upon ascent entrain foreign material (primarily mantle xenocrysts). Thus, they can be used to probe the composition of and processes within the ancient lithospheric mantle. Whereas similar orangeite dyke swarms in South Africa typically span < 10 km, the considerable size of this swarm (> 50 km along strike and ~10 km wide) and number of closely-spaced dykes offers a unique opportunity to investigate the Kaapvaal SCLM on an unprecedented spatial scale. In this contribution we present the whole rock major and trace element abundances, and the radiogenic isotope compositions of the dykes.

The Bushveld orangeites are mafic-ultramafic (whole rock Mg# of 65 to 88) and have overlapping major element abundances to other Kaapvaal orangeites, with significant similarity to the coeval Swartruggens orangeite dyke swarm (Coe et al., 2008). Trace element abundances of the Bushveld dykes are less consistent with Kaapvaal orangeite variability, displaying greater ranges in concentrations of certain elements (e.g. La, Th, Ba) despite being generally relatively depleted in these elements.

Radiogenic isotope compositions of the orangeites typically confine to the global orangeite variability, with radiogenic Sr (87Sr/86Sriof 0.70642 to 0.70787) and unradiogenic Hf compositions (ɛHfi of -18.3 to -8.3). Initial Nd compositions are generally unradiogenic (ɛNdi of -11.6 to -9.0), conforming to values of global orangeites, however three samples display elevated initial Nd (ɛNdi of -5.4 to -0.4) and plot in a similar Sr-Nd compositional space to Kaapvaal transitional kimberlites.

Using the trace element variations and radiogenic isotope compositions we aim to investigate the geochemistry of the mantle source regions tapped by the orangeites and whether we can identify changes in source characteristics on a swarm scale.

References:

Coe, N. et al. (2008) Cont. Min. Pet. 156(5). 627-652.

Hughes, H.S.R. et al. (in prep).
Calcite interval in aragonite seas: Geochemical characterization of post-extinction oolites at the Triassic-Jurassic boundary and their implications
Authors: Urban Ingrid , Richoz Sylvain
Published: March 2021

The End-Triassic Mass Extinction (ETME) is one of the five major mass extinctions of the Phanerozoic. The deposition of ooids is atypically high in the direct aftermath of major extinction events, including the ETME. Ooids were intensively investigated both petrographically and sedimentologically in the past decades; but only recently their potentialities as archives for the original chemical composition of the oceans where they formed, have gained awareness. Here we present stratigraphical, sedimentological and geochemical aspects for a mid-Norian-Hettangian section from the Emirates.

Petrographic analyses provided a detailed morphological classification of post-ETME coated grains, supported by point counting of two isochronous geological sections. FE-SE-EDX imaging unraveled peculiar µm-scale features linked to morphology, diagenesis and biotic interaction in the cortex. LA-ICP-MS analyses were performed for specific major and trace elements. Post-extinction oolites show high variability in size and development of the cortex. They range from small (~ 300 µm) and superficial coating, to bigger (up to 800 µm) and well developed. The degree of micritization highlights different oxic conditions in the diagenetic environment. LA-ICP-MS analyses give insights into seawater redox conditions during ooids formation, siliciclastic contamination, diagenetic processes and the role of bacterial strain in shaping the ooids. Petrographical and geochemical data point out to a calcitic deposition of these ooids as odd with the general consideration that the Late Triassic to Early Jurassic was part of the Aragonite sea. This has major implication on the understanding of the carbonate saturation in the oceans just after the mass-extinction and on the interpretation of several proxies as the C and Ca isotope-system.

 

 
Modelling the impact of soil processes on the N and O isotope signatures of nitrate in groundwater
Authors: Otero Neus , Sebilo Mathieu , Mayer Bernhard , Gooddy Daren , Lapworth Dan , Surridge Ben , Petelet-Giraud Emmanuelle , Kloppmann Wolfram
Published: March 2021

Stable isotope fingerprinting is widely applied to plant-soil-groundwater systems in an aim to identify and even quantify the sources of nitrates found in groundwater. Frequently, in such studies, the δ15N and δ18O values of nitrogen sources, such as inorganic fertilizers and manure, are directly compared to the isotope signatures of nitrate encountered in groundwater bodies below agricultural watersheds. We submit that the underlying assumptions (conservative behavior of isotope composition, rapid transfer from surface to groundwater) may only be realistic under very specific conditions whereas, in most cases, significant isotope effects exerted by the soil-microbial-plant system on the δ15N and δ18O values of nitrate need to be taken into account when attempting a quantitative apportionment of sources of groundwater nitrate.

We hypothesise that the isotopic signature of nitrate exported from below the root zone and migrating towards the groundwater will reflect the nitrogen isotope composition of the soil organic N pool, rather than the isotope composition of source fertilizer or organic amendments, due to processes that reset source isotope compositions within soil N pools. We test this hypothesis using empirical observations from a diversity of settings, in France, Spain and Canada with a relatively constant historic anthropogenic N source or a simple and well constrained landuse history. Furthermore, through the use of a process-based model (SIMSONIC, Billy et al., 2010) we estimate to what extent the isotopic composition of the predominant N input to the soil-microbial-plant system and the soil N pool has been modified in an attempt to consider these changes in source apportionment studies elucidating the sources of groundwater nitrate.

This research was supported through the Consortium award MUTUAL, by the LE STUDIUM® Loire Valley Institute for Advanced Studies via its SMART LOIRE VALLEY (SLV) fellowship programme, co-funded by the H2020 Marie Sklodowska-Curie programme, Contract No. 665790.

 

Billy C., Billen G., Sebilo M., Birgand F., Tournebize J. (2010) Nitrogen isotopic composition of leached nitrate and soil organic matter as an indicator of denitrification in a sloping drained agricultural plot and adjacent uncultivated riparian buffer strips. Soil Biology and Biochemistry, 42, 108-117.