bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance analysis of missing data imputation methods for daily groundwater hydrographs using typical gap patterns
Authors: Bikše Jānis , Kalvāns Andis , Retike Inga , Jemeļjanova Marta
Published: March 2022

Regular and gapless observations are necessary to perform a range of statistical analysis on the parameter of interest. Groundwater level (GWL) hydrographs  are often recorded at irregular frequencies and have time periods without any observations. As a result, groundwater level hydrographs have missing values. Typically groundwater hydrographs are removed from further analysis if large gaps are present, while each groundwater observation point is valuable and methods exist that can impute (fill in) the missing observations. 

This study aims to evaluate performance of machine learning methods to prepare gapless daily groundwater level hydrographs and to assess the imputation error according to various approaches. Filled groundwater level hydrographs will further be used  to identify typical groundwater level patterns in the Baltic region.

The performance of two machine learning imputation methods - missForest and missMDA - along with conventional approaches (linear interpolation, mean imputation) - were tested. A subset of the GWL observation data from Lithuania, Latvia and Estonia were used for the time period from 2011 to mid-2019 comprising 283 groundwater monitoring wells. Cluster analysis of the temporal distribution of actual missing values in the GWL time series provided 13 different gap patterns. Next a corresponding number of artificially generated gap distribution scenarios were defined. The performance of various gap-filing approaches were then evaluated by imputing each artificially generated gap pattern in each hydrograph. Results indicated that imputation performance varies among different clusters of missing value patterns, while generally the best performance was achieved by the missForest algorithm.

This research is funded by the Latvian Council of Science, project “Spatial and temporal prediction of groundwater drought with mixed models for multilayer sedimentary basin under climate change”, project No. lzp-2019/1-0165.
Diapycnal fluxes and overturning from a tracer release experiment in a tidal canyon
Authors: Messias Marie-Jose , Mercier Herle , Ledwell James , Naveira Garabato Alberto , Ferrari Raffaele , Alford Matthew
Published: March 2022

The overturning of the ocean has been classically described by sinking at high latitudes and upwelling of deep water in the ocean interior. However, measurements showing bottom enhanced mixing have suggested that the ocean interior experiences downwelling, and it has been recently proposed that the upwelling of deep water should arise over sloping boundaries. The Bottom Boundary Layer Turbulence and Abyssal Recipes project was set up to test this paradigm in the Rockall Trough, a natural laboratory of the deep ocean overturning. We conducted a tracer experiment that began by the injection of 15 kg of long lived inert SF5CF3 on the deep part of a tidal canyon in July 2021. The injection was performed in the bottom boundary layer, ~7 meters above the bottom, along streaks between 1800 m and 2000 m depth, tagging water at potential temperature of 3.6°C within a temperature window of 0.1°C. Within 24 hours we started the tracer survey along the full canyon length for two weeks (totalling 81 stations) and we report here on the integrated diapycnal fluxes (upwellings and downwellings) at key locations between 900 m and 2600 m depth, at different time steps from neap to spring tides. The tracer dispersion along the canyon unprecedently documents a rapid diapycnal upwelling of the tracer ranging from 50 to 300 meters per day driven by tidal mixing implying an overturning circulation. As the tracer evolved in the canyon under tidal sloshing, its leading edge was detected reaching 8.5°C at the canyon head as we entered spring tides. We will also report  on the tracer chase outside of the canyon   to explore the contribution of sloping boundary mixing to ventilation at the scale of the Rockall Trough.
 
First experience with GNSS data quality monitoring in the distributed EPOS e-infrastructure
Authors: Bamahry Fikri , Legrand Juliette , Bruyninx Carine , Fabian Andras
Published: March 2022

The European Plate Observing System (EPOS) is a very large and complex European e-infrastructure that provides pre-operational access to a first set of datasets and services for Solid Earth research. The EPOS-GNSS Data Gateway provides, through an Application Program Interface (API) and a web portal, access to GNSS (Global Navigation Satellite Systems) RINEX data from a distributed infrastructure of data nodes. Currently, ten EPOS-GNSS nodes have been installed, and three of them are still in the pre-operational phase. To monitor the long-term data quality of EPOS-GNSS stations at the nodes level, ROB is developing a new service. The first step of this service is a web portal (www.gnssquality-epos.oma.be) that provides access to data quality metrics of the RINEX data available from the different EPOS-GNSS nodes.

The web portal presents plots of the long-term tracking performance of more than 1000 EPOS-GNSS stations. The plots focus on several data quality metrics such as the number of observed versus expected observations, the number of missing epochs, the number of observed satellites, the number of cycle slips, and multipath values on code observations. These metrics have been computed at the node level using GLASS and Anubis Software (https://gnutsoftware.com/software/anubis). The metrics provide helpful information for node managers or station users to assess the EPOS-GNSS station’s performance and detect potential degradation of the RINEX data quality. The outlook of this work is to investigate the possible usage of data quality metrics to detect data unsuitable for high-precision GNSS analysis for geophysical or meteorological applications. Here, we will present the newly developed web portal, the considered data quality metrics, and some preliminary results of this ongoing work.
Variance component estimation for co-estimated noise parameters in GRACE Follow-On gravity field recovery
Authors: Lasser Martin , Meyer Ulrich , Arnold Daniel , Jäggi Adrian
Published: March 2022

Temporal gravity field modelling from GRACE Follow-On deals with several noise sources polluting the observations and the system of equations, be it actual measurement noise or mis-modellings in the underlying background models. One way to collect such deficiencies is to co-estimate additional pseudo-stochastic parameters in the least-squares adjustment which are meant to absorb any kind of noise while retaining the signal in the gravity field and orbit parameters. In the Celestial Mechanics Approach (CMA) such pseudo-stochastic parameters are typically piece-wise constant accelerations set up in regular intervals of e.g., 15 min, and an empirically determined constraint is added to confine the impact of the additional quantities. As the stochastic behaviour of these parameters is unknown because they reflect an accumulation of a variety of noise sources, Variance Component Estimation (VCE) is a well established tool to assign a stochastic model to the pseudo-stochastic orbit parameters driven by the observations.
In the simplest case the magnitude of the constraints of the pseudo-stochastic orbit parameters can be determined fully automatically.

We present results for GRACE Follow-On gravity field recovery when extending the CMA by stochastic models for the piece-wise constant accelerations computed with VCE and provide noise and signal assessment applying the quality control tools routinely used in the frame of the Combination Service for Time-variable gravity fields (COST-G).
Surface layer turbulence response to spanwise heterogeneous vegetative canopies
Authors: Winiarska Ewelina , Soffer Ran , Klopfer Harel , van Hout Rene , Liberzon Dan
Published: March 2022

When the prevailing geostrophic flow is parallel to the heterogeneity, large secondary spanwise circulations emerge within the flow that affect surface fluxes of momentum, heat, and mass. By means of wind-tunnel measurements, the influence of spanwise heterogeneity on the possible appearance of secondary circulations and their effect on evaporative fluxes is investigated. The experiments were performed at the environmental wind-tunnel at the Technion. A 5-m long canopy, modeled after available leaf-area index data for corn, consisted of triangular perforated sheet elements (h = 20 cm) arranged in an in-line setup. The atmospheric boundary layer conditioned by spires and a shear generator has a boundary layer thickness of about 70cm. Measurements were performed by combined hot wire anemometry and stereo-PIV enabling to resolve the turbulent flow characteristics both spatially and temporally. Measurements were performed at a bulk flow velocity of 3.0 m/s (Reh = 38400). Several sets of stereo-PIV measurements in fifteen wall-parallel planes positioned between 0.5h to 1.5h were acquired. In addition, the evaporation rates at various locations within the canopy were obtained by means of in-house made sensors. Measurements were performed for a homogeneous canopy and one that exhibited spanwise heterogeneity under the bulk flow conditions. Turbulent flow characteristics, including turbulence production terms, will be presented. The effects of the heterogeneity on the coherent structures near the canopy top are analyzed using quadrant and spectral analyses.
High resolution geophysical study of Lake Maninjau, West Sumatra, Indonesia
Authors: Oladipo Olajide , Bouvet De La Maisonneuve Caroline , Waldmann Nicolas
Published: March 2022

Lacustrine sediments that fill volcanic craters like Lake Maninjau in West Sumatra (Indonesia) are pristine archives of past natural geological processes such as flooding, slope failure induced landslides, and volcanic eruptions. The aim of the study is to investigate the shape, and distribution of the morphological features found on the floor of Lake Maninjau as well as attempt the seismic stratigraphy of its basin fill. This is achieved by utilizing a 2-16 KHz Sub Bottom Profile seismic reflection survey that is complemented with a high-resolution sonar scanning (bathymetry) of Lake Maninjau.

The results show that the floor of Lake Maninjau is flat (~8 km wide) and reaches a maximum depth of ~168 m at the lake depocenter. Shallow sediment cores show that hemipelagic sediments predominantly cover its floor. The lake floor physiography is divided into five provinces (shelf, plateau, lake shoulder and slope, central sub-basin, and southern sub-basin), that are characterized by different morphological features with distinct responses on seismic data. These features include Mass Wasting Complexes (MWCs), blocks, gully-like features, and a lake-center dome. The MWCs are found in the northern, southern, and southeastern parts of the lake, and are occasionally characterized by embedded ~0.9-0.4 m high blocks that are interpreted to result from debris avalanches possibly accompanying earthquakes or extreme climate events. Debris flow sediments are identified on the sediments of the slope and basin shoulders, which are represented by locally constrained chaotic reflections that exhibit synchronicity. A central dome is well identified and interpreted to be of volcanic origin and may indicate a reactivation of the Maninjau volcano. The basin lacustrine infill consists of five seismic facies that serve to identify six seismic stratigraphic seismic units (SU I to SU VI), with each representing a distinctive phase in the lake evolution.

This study gives insights into the morphology and distribution of sub-lacustrine features identified within the basin fill of Lake Maninjau. It further confirms that Lake Maninjau archives past natural processes and lays the foundation for an improved understanding of the provenance of sediments and possible future utilization of the lake archive as a record of both environmental and climate change.
Influence of recent droughts on carbon cycling in the Elbe estuary
Authors: Rewrie Louise , Voynova Yoana , Brix Holger , Ollesch Gregor , Baschek Burkard
Published: March 2022

Climate projections show high temperature extremes, meteorological droughts and heavy precipitation events are set to increase across Europe (Barros et al., 2014), where the decadel average has already increaed, with temperature in 2002-2011 already 1.3°C±0.1°C above the 1850-1899 mean (Barros et al., 2014). The observed seasonal precipitation pattern presents drier summers and wetter winters across Europe, also mirrored in river flow changes. Across small river catchments in Europe from 1962 to 2004, winter period showed positive trends whereas summers were characterized by negative trends in river flow (Stahl et al., 2010). Such changes can alter the residence time of an estuary. Estuaries are biogeochemical hotspots, and critical zones for carbon cycling, and changes in the hydrological balance, still largely not well characterized, may influence processes within the water column. 

The present study will assess the potential impacts of droughts on the carbonate system in the Elbe estuary. One of the largest in central Europe, the Elbe River catchment spreads over approximately 150,000 km2 in four countries. Between 2014 and 2018, regions of Northern Germany have been under drought conditions during certain months (UFZ, 2018), reducing discharge in the Elbe River. From 2014, annual Elbe river discharge has been relatively low, where 2018 exhibited the lowest annual mean river discharge of 441 m3 s-1 since 1992. Model projections show the annual river discharge for the Elbe river is likely to remain low at 410 m2 s-1 in 2046-2055 compared to >550 m2 s-1 in 1960-1990 (Krysanova et al., 2005).

Analysis of the long-term FGG Elbe (Flussgebietsgemeinschaft Elbe) records of dissolved inorganic carbon (DIC) in the mid to lower Elbe estuary show that over spring and summer months DIC values have increased with time (1997-2018). In this period, DIC increased from the freshwater to the mesohaline region, followed by a decrease to the polyhaline zone. This is opposing to previous DIC patterns in the early 1980s, where DIC decreased towards the mid-estuary after which increased to the outer estuary. An increase in DIC in the mid-estuarine region coincided with increased turbidity and extended residence time, and during the productive months with higher organic matter from upstream regions.  This could suggest that more time for heterotrophic activity and availability of labile organic matter, acts to enrich DIC within the water column in the turbid regions, thus changing carbon cycling within the estuary. Further analysis will focus on the changes in river discharge and inorganic carbon during the past two decades, thus inclusive of low discharge and drought conditions.
Rice monitoring in Lower Mondego (Portugal) using multi-temporal Sentinel-2 satellite images: comparison between different irrigation conditions
Authors: Gerardo Romeu , de Lima Isabel
Published: March 2022

Irrigated rice agriculture, if traditionally conducted applying continuous flooding, requires much more irrigation water than non-ponded crops. This is usually a constraint in areas facing water scarcity issues that might directly affect rice production and the competition for water. Climate change might furthermore amplify current difficulties, depending on the hydrological regime, the availability of irrigation infrastructures, rice variety and rice agronomic management practices, among other factors.

Whereas different water availability conditions determine differences in rice growth and yields, the response of this crop is not well established for the rice producing area of the Lower Mondego region (Portugal), which is identified as an area vulnerable to climate change, in particular with respect to increasing precipitation and temperature variability. In coastal areas’ lowlands, the groundwater table (e.g., depth and quality) can also play an important role, namely under the influence of sea level rise. For this region, in the proximity of the Atlantic Ocean, we report on using remote sensing tools to assess irrigated rice growth, in areas i) served by a full gravity irrigation system, and ii) fed directly from a small, non-regulated, river. The data used in our study include land surface images of rice cultivated areas obtained from satellite Sentinel-2A during several years (including a particularly dry year). Although the remote sensing data available from satellite multispectral imagery present some practical constraints (e.g. cloud cover, resolution), results from this study show that remote sensing tools, including the Normalized Difference Vegetation Index (NDVI), are able to differentiate between established rice growth phases, which highlights their usefulness as rice monitoring tools and potential role in assessing the impact of applying different irrigation and agriculture management practices on rice cultivation.

This work was conducted under the umbrella of the international project MEDWATERICE (www.medwaterice.org) that focuses on improving the sustainable use of water in the Mediterranean rice agro-ecosystem and aims at exploring the opportunity to apply water-saving, alternative, rice irrigation methods.
Slip distribution of the 29 December 2020 Mw 6.4 Petrinja earthquake (Croatia) from dense geodetic benchmarks and optical image correlation measurements
Authors: Henriquet Maxime , Métois Marianne , Hollingsworth James , Kordić Branko , Lasserre Cécile , Benedetti Lucilla
Published: March 2022

The intracontinental Mw 6.4 Petrinja earthquake (Croatia) of December 29th, 2020, is one of the strongest earthquakes recorded in slowly deforming Eastern Europe. In low strain contexts, sparse seismic monitoring and the rare occurrence of strong earthquakes often prevent the detailed analysis of coseismic rupture. Discontinuous right-lateral coseismic surface rupture and extensive damages reported in the area suggest a relatively shallow seismogenic source for the Petrinja earthquake. Here, we leverage dense near field measurements from optical image correlation and numerous geodetic benchmarks for cadastral and engineering purposes to model the surface and subsurface slip distribution of the Petrinja earthquake. Optical image correlation based on pre-event (7th December 2017) WorldView and post-event (12th and 20th February 2021) Pleiades satellite images is used to refine the trace of the segmented surface rupture and derive coseismic displacements in the very near-field (< 1km from the fault). The ~13 km long imaged fault trace reveals an en échelon geometry in agreement with field observations, and a right-lateral slip reaching up to ~1 m. These results are consistent with the displacement field derived from the dense cadastral GNSS measurements. No additional conjugate fault is visible on the image correlation outcomes. The elastic inversion of these data shows that the coseismic slip was localized on a near-vertical strike-slip fault at shallow depth, < 10 km, and that significant slip reached the surface. It also suggests that the fault bending near Župić interfered with the rupture propagation as the largest slip, > 3 m, is localized on the northern section at depth < 5 km. In conclusion, this study not only provides new constrains on the seismogenic source of the Petrinja earthquake, it also underlines the potential of optical image correlation and cadastral GNSS measurements to retrieve a dense surface displacement field in the epicentral area of moderate intracontinental earthquakes.

 
Ionospheric elves powered by negative Narrow Bipolar Events in overshooting thunderclouds
Authors: Liu Feifan , Neubert Torsten , Chanrion Oliver , Zhu Baoyou , Lu Gaopeng , Lyu Fanchao , Dimitriadou Krystallia , Lei Jiuhou , Østgaard Nikolai , Reglero Victor
Published: March 2022

Elves are rapidly expanding rings of optical emissions in the lower ionosphere. Narrow bipolar events (NBEs) are signatures in radio signals from intra-cloud discharges. They are thought to be fast streamer breakdown that may trigger the onset of lightning and blue jets. However, there is a lack of experimental evidence on whether the streamer discharges of NBEs carry sufficient currents to generate elves in the lower ionosphere. Here, we report the first simultaneous observation of NBEs and elves that confirm this hypothesis. The NBEs are observed simultaneously from the ground by an array of wave receivers located in China and from space by spectral measurements by the Atmosphere-Space Interactions Monitor (ASIM) on the International Space Station (ISS). We observe thirteen negative and six positive NBEs produced in four thunderclouds penetrating into the stratosphere. Five NBEs are accompanied by elve emissions observed in the near-ultraviolet of the Lyman–Birge–Hopfield (LBH) band.  They were at ~18 km altitude, and their peak currents, estimated by a ground-based lightning detection network, were larger than 135 kA. The observations show that the impulse currents of the streamers are of sufficient magnitude to power elves, thereby adding to the new pathways that thunderstorms affect the lower ionosphere. 
Experimental study of the impact of hydration extent on the strength of the lower continental crust
Authors: Mohrbach Lisa Katharina , Renner Joerg , Incel Sarah
Published: March 2022

Previous experimental data and field observations demonstrate that fluids have a significant influence on rock strength. The relation between strength and hydration extent of the lower continental crust is still poorly constrained and thus a matter of an ongoing debate. We tested the impact of hydration extent on the strength of rocks representing the lower continental crust by performing deformation experiments on various plagioclase-epidote mixtures as well as on natural granulite samples in a Grigg's type deformation apparatus. In these samples, the plagioclase component represents rocks of the lower continental crust and epidote reflects hydration extent, because, alongside with quartz, kyanite and jadeite or albite, it forms as a decomposition product of plagioclase at high-pressure/ high-temperature conditions in the presence of even small amounts of fluids. To quantify the relation between strength and epidote content, we conducted the tests on plagioclase-epidote powders with a grain size of 90-135 mm and plagioclase-epidote ratios of 100:0, 99:1, 98:2, 95:5, 90:10, 85:15, and 0:100. The pre-dried powders were first hot-pressed at 550 °C and a confining pressure of 1 GPa for 3 h in the Griggs apparatus. Mixtures were subsequently deformed at 1 GPa and 550 to 650 °C at strain rates of 5·10-6 to 5·10-5 s-1. All stress-strain curves show pronounced maxima followed by strain softening towards a final strength. The deformation data yield an exponential decrease of the ultimate strength with increasing epidote content. Investigations of the microstructures of samples deformed at 550 °C and 5·10-5 s-1 using the SEM and polarized light microscopy reveal cataclastic flow by grain-scale fracturing of both epidote and plagioclase and the rotation and alignment of epidote grains at angles between 60° and 70° to the maximum principal stress  σ1. In addition, plagioclase grains show pronounced undulatory extinction but we found no evidence for deformation twinning. Some samples exhibit networks of conjugate bands of fine-grained plagioclase surrounding larger plagioclase grains oriented at an angle of around 50° towards σ1. These bands are mostly visible in samples without epidote.
Zooplankton and Micronekton products from the CMEMS Catalogue: state of the current product and development plan
Authors: Titaud Olivier , Conchon Anna , Lehodey Patrick
Published: March 2022

Since mid-2019, meso-zooplankton and micronekton reanalyses (large past time series that are processed with time-consistent forcings) are available and regularly extended for the CMEMS catalogue. The product (also known as MICRORYS) is computed using SEAPODYM-LMTL, the Lower and Mid Trophic levels model of the Spatial Ecosystem And POpulation DYnamic Modeling framework. Meso-zooplankton organisms (200µm-2mm) constitute the low-trophic level. These organisms are transported along with the water masses. Micronekton organisms, constituting the mid-trophic level, are bigger organisms (2-20cm) able to swim over short distances. SEAPODYM models the spatial and population t dynamics of the LMTL population with a system of advection-diffusion-reaction equations. The vertical dimension is simplified into three layers (namely epipelagic, upper, and lower mesopelagic). Layers matches the vertical distribution of organisms that is observed. The six micronekton groups are defined according to their diel vertical migration  from the surface at night to the deep ocean during the day. At the moment MICRORYS products use a global configuration of SEAPODYM at 1/12° daily resolution. This product has evolved considerably since the first delivery. We propose here to review the state of the art of this product. Some case studies and the developments that are expected in the near future, especially those concerning a better estimation on high latitudes will be presented.
Water resources management of grasslands under climate change in the historic rural landscape of Lessinia Regional Park (Veneto, Italy)
Authors: Chen Lin , Qiu Junliang , Tarolli Paolo
Published: March 2022

Grasslands cover a large portion of the terrestrial ecosystems, and are vital for biodiversity conservation, environmental protection and livestock husbandry. However, climate change scenarios (e.g., drought) could pose grasslands under threat seriously affecting their ecosystem services role. Ponds, an indispensable part of water storage on the grassland, could exert a key role in water supply during extreme water scarcity scenarios, controlling the cycle of water, nutrients, and sediments, supporting livestock and agricultural land production and maintaining the ecologic functions of pastures. Ponds could indeed be seen as a sustainable solution for more resilient grassland landscapes. The climate change forcing will have an impact on grassland extension and spatial distribution of ponds. On the other hand, in literature small ponds have not been satisfactorily investigated in the study of ecosystem service due to the inconformity of geographic location.

In this context, we considered the pastures located in Lessinia Regional Park (Veneto, Italy) with elevation ranging from 800 up to 1600 m asl. The climate is classified as cold with no dry season and warm summer with annual rainfall greater than 1500 mm. The area was recently listed (September 2020) in the Italian national register of historic rural landscapes by Italian Ministry of Agricultural, Food and Forestry Policies. The area is characterized by a dense distribution of ponds, supporting livestock activities. We investigated the ecosystem service role of these ponds, and their spatial patterns and fragmentation (also considering remote sensing, e.g., Sentinel-2) under different weather condition: wet and drought in Lessinia Regional Park. Our work is significant for estimating the ecosystem service value by the integration ponds benefit (e.g., visual ponds and walking ponds) with cultural service. This study will provide scientific basis for rational allocation of environmental resources, formulation of regional protection and management planning, and promotion of sustainable development of man-land relationship.
Modelling the effects of NBS adoption in mitigating soil losses of a land reclamation area in the Massaciuccoli lake catchment (Central Italy) 
Authors: Pignalosa Antonio , Silvestri Nicola , Pugliese Francesco , Gerundo Carlo , Corniello Alfonso , Del Seppia Nicola , Lucchesi Massimo , Coscini Nicola , De Paola Francesco
Published: March 2022

Many types of Nature-Based Solutions (NBSs) have been applied worldwide to mitigate impacts of hydro-meteorological hazards produced by anthropic activities such as grazing and agriculture. Among them, vegetated buffer strips (VBSs) and winter cover crops (WCCs) are suitable solutions for reducing runoff and soil erosion rates from cultivated fields. However, their mitigating effects depends largely on local conditions such as morphology and soil nature.

This study investigated these aspects by modelling the NBS effects on soil and water dynamics in two test sites located within the Massaciuccoli agricultural plain (Vecchiano, Pisa, Central Italy) and characterised by different soil types (peaty and silty soils). The SWAT+ model has been chosen to simulate hydraulic and hydrological phenomena using high-resolution data such as digital terrain models (DTMs) from close-range photogrammetry, detailed land cover mapping, actual crop rotations, and detailed calendars of agronomic operations. We considered two types of NBSs: i) 3 m wide VBSs planted along both sides of field ditches, covering about 10% of the agricultural land, and ii) WCCs sowed after harvesting summer cash crops. Both NBSs exert their action on 30% of the experimental area. The mitigating effect was tested by comparing simulation results from NBS and control (conventional agriculture) scenarios under ongoing climatic conditions and future climate changes.

Results indicated that VBSs and WCCs showed different capabilities to reduce runoff and sediment losses, and the adoption of both can enhance the mitigation effect significantly. NBSs resulted effective also in completely flat areas since slight topographic irregularities can cause local preferential flows resulting in high runoff rate and sediment losses. Furthermore, it is demonstrated how the soil variability in texture and organic matter content can affect the amount of runoff and sediment loss on a local scale. Consequently, the mitigating effects of NBS can be closely driven by the soil nature and heterogeneity. This influence is even more significant under extreme climatic conditions such as higher temperatures and more aggressive rainfall events. In these cases, NBSs can play an essential role in mitigating runoff and soil erosion phenomena on fine-textured mineral soils. In contrast, they lose much of their effectiveness on peat soils.
Time-lapse stereo-cameras and photogrammetry for continuous 3D monitoring of an alpine glacier
Authors: Ioli Francesco , Bianchi Alberto , Cina Alberto , De Michele Carlo , Pinto Livio
Published: March 2022

Photogrammetry and Structure-from-Motion have become widely assessed tools for geomorphological 3D reconstruction, and especially for monitoring remote and hardly accessible alpine environments. UAV-based photogrammetry enables large mountain areas to be modelled with high accuracy and limited costs. However, they still require a human intervention on-site. The use of fixed time-lapse cameras for retrieving qualitative and quantitative information on glacier flows have recently increased, as they can provide images with high temporal frequency (e.g., daily) for long-time spans, and they require minimum maintenance. However, in many cases, only one camera is employed, preventing the use of photogrammetry to compute georeferenced 3D models. This work presents a low-cost stereoscopic system composed of two time-lapse cameras for continuously and quantitatively monitoring the north-west tongue of the Belvedere Glacier (Italian Alps), by using a photogrammetric approach. Each monitoring station includes a DSLR camera, an Arduino microcontroller for camera triggering, and a Raspberry Pi Zero with a SIM card to send images to a remote server through GSM network. The instrumentation is enclosed in waterproof cases and mounted on tripods, anchored on big and stable rocks along the glacier moraines. The acquisition of a defined number of images and the timing can be arbitrary scheduled, e.g., 2 images per day acquired by each camera, around noon. A set of ground control points is materialized on stable rocks along the moraines and measured with topographic-grade GNSS receivers at the first epoch to orient stereo-pairs of images. From daily stereo-pairs, 3D models are computed with the commercial Structure from Motion software package Agisoft Metashape, and they can be used to detect morphological changes in the glacier tongue, as well as to compute daily glacier velocities. The work is currently focused on improving the orientation of stereo-pairs: the use of computer vision algorithms is under study to automatize the process and increase the robustness of consecutive orientation of stereo-images, e.g., by including images coming from different epochs in the same bundle block adjustment and dividing them afterwards for dense 3D reconstruction. Change detection can be then computed from 3D point clouds by using M3C2 algorithms. Although the stereoscopic system is already installed on the Belvedere Glacier and it is properly taking daily images of the glacier tongue, the processing workflow of stereo-pairs needs to be tuned and automatized to enable high-accurate continuous 3D photogrammetric monitoring of an alpine glacier, computing short-term and infra-seasonal ice volume variations and velocities, as well as detecting icefalls.
Source mechanisms of earthquakes induced by the 2018 and 2020 geothermal stimulations in Espoo/Helsinki, southern Finland
Authors: Rintamäki Annukka , Heimann Sebastian , Dahm Torsten , Hillers Gregor
Published: March 2022

An experimental ~6 km deep enhanced geothermal system in Otaniemi, in the Helsinki capital region, southern Finland, was stimulated in 2018 and 2020. During the two stimulations that lasted seven and three weeks, respectively, signals of the induced earthquakes with a maximum local magnitude of 1.8 were recorded with dense and diverse seismic networks. The intraplate southern Finland setting of the experiment yields an intriguing opportunity to study earthquake and rock failure processes in the precambrian Fennoscandian Shield where the level of natural seismicity is comparatively low. The high confining pressure of 180 MPa at 6 km depth defines the key characteristics of the stress field, together with the previously estimated North-110-degrees-East direction of the maximum horizontal stress. The competent crystalline bedrock has very low attenuation, and yields high signal-to-noise ratio seismograms even at relatively high frequencies. We study the source mechanisms of ~250 induced earthquakes with Mw > 0.5. We perform probabilistic full moment tensor analysis with the Grond package of the software suite Pyrocko. We use data sets from the 2018 and 2020 stimulation experiments. Both experiments were monitored with more than 100 three-component surface stations operated by the Institute of Seismology, University of Helsinki, and 12 three-component borehole stations maintained by the St1 developer company installed at around 300 m depth. The diverse network elements help to evaluate the consistency of the results. We first present results of a detailed analysis of a small event subset characterized by the best data quality and solutions to assess the robustness of the different tensor components to different processing choices. This includes a comparison of surface and borehole sensor data. This allows us to conclude that the majority of the analysed earthquakes have a dominant reverse faulting mechanism and a small subset of events has strike slip mechanisms, which is compatible with solutions reported by the developer group. The predominant fault plane orientations are in agreement with the ambient stress conditions that also seem to control the thrust mechanism. Based on the best quality solutions we discuss the significance of the obtained non-double couple moment tensor components to assess if significant opening or closing elements in the induced earthquake source reflect genuine physical processes or spurious effects associated with imperfect resolution.
Peculiar Comets Ejected Early In Solar System Formation
Authors: Anderson Sarah E. , Petit Jean-Marc , Noyelles Benoît , Mousis Olivier , Rousselot Philippe
Published: March 2022

Comet C/2016 R2 PanSTARRS presents an unusually high N2/CO abundance ratio, as well as a heavy depletion in H2O, making it the only known comet to have this composition. Two studies have independently estimated the possible origin of this comet from building blocks formed in a peculiar region in the protoplanetary disk, near the ice line of CO and N2. Here we explore the potential fates of comets formed from these building blocks using a numerical simulation of early solar system formation and tracking the dynamics of these objects in the Jumping Neptune scenario. We find that objects formed in the region of the CO- and N2- icelines a are highly likely to be sent towards the Oort Cloud or ejected from the Solar System altogether on a relatively short timescale, thus offering a potential explanation for the scarcity of comets with R2’s unique composition.  
Drought sensitivity of Pinus sylvestris L. on century old charcoal rich Technosols in the North-German Lowland
Authors: Al Jobayer Md Asif , Bloß Katharina , Porsch Christopher , van der Maarten Ernst , van der Maaten-Theunissen Marieke , Bonhage Alexander , Raab Alexandra , Schneider Anna , Raab Thomas
Published: March 2022

Soils on relict charcoal hearths (RCHs), i.e. aged charcoal rich Technosols, feature documented legacy effects regarding their physical and chemical soil properties. These forest soils result from the pre-/early-industrial production of charcoal in upright standing hearths. Today, RCHs are found in forested areas as circular microrelief structures with average diameters of about 10 meters that contain technogenic soil horizons of about 20 cm thickness. RCH soils are most distinctly characterized by their large content of pyrogenic soil organic matter and consequently increased total carbon contents. The resulting changes in the soils’ cation exchange capacity, soil acidity, total nitrogen contents and total element stocks are often significant. Furthermore, changes in soil physical properties like a lower bulk density and a higher porosity result in changed soil-water- and temperature regimes. Combined, these effects potentially result in unique soil microhabitats that are restricted to relatively small, clearly defined areas in many forest ecosystems.

Recent studies on RCH soils increasingly focus on potential changes in microbiological and vegetational composition and abundances and report diverse effects. Here, we study the effects of century old charcoal rich Technosols on the drought sensitivity of Scots pine (Pinus sylvestris L.) on three RCH sites located in Lower Lusatia, Saxony (Germany). Through dendrochronologial analysis of increment cores and historical climate data, we study climate-growth relationships for trees on RCH soils and reference forest soils for two periods (AD 1963-1992 & AD 1990-2019). Furthermore, we determine pointer years and components of resilience to quantify the trees’ reaction to extreme weather conditions. This analysis was accompanied by soil sampling and analysis on the RCH sites and adjacent reference forest soils. Here, we present preliminary results and discuss them in the context of findings from other studies on RCH soils.
Validation, systematization and support for the implementation of a hydrological and hydrogeological model of the Katari basin and minor Titicaca lake
Authors: Criollo Rotman , Scheiber Laura , Poza Laura , Simunoivc Pedro , Vázquez-Suñé Enric
Published: March 2022

The Katari Basin and Minor Lake of Titicaca (Bolivia) is one of the most populated and under pressure basins in the country where approximately 10% of the population lives at the national level (one million inhabitants). Urban development in the basin is rapid and is characterized by poor territorial planning and socio-productive patterns without appropriation in terms of caring for the urban, peri-urban, rural and aquatic environment, which has led, among others, to an accelerated and severe deterioration of water quality throughout the basin. It is for this reason that it is necessary to integrate the management of the productive aspects of the exploitation of its water resources with various environmental and socio-economic aspects of the area.

This study is within the framework of the "Lake Titicaca Sanitation Program" financed by the Inter-American Development Bank (IDB). The main objective of this program is to contribute to the decontamination of the Katari River basin and MinorTiticaca Lake and generate the necessary conditions to improve the quality of life of the population in this region, which is included in the different actions for the development and implementation of the Katari Basin Master Plan. The Katari Basin Management Unit (UGCK) will be the main beneficiary, which depends directly on the Ministry of Environment and Water (MMAyA) of Bolivia.

The implementation of a hydrological and hydrogeological model of the Basin would allow us to understand its operation; as well as quantify the general water balance of the Katari Basin and Minor Titicaca Lake. The specific objectives are: (i) Validate the conceptual hydrological model of the Katari basin and minor Titicaca lake; (ii) Update the existing spatial database for later use in the application of the hydrogeological conceptual model of the Katari basin and Minor Titicaca Lake; and (iii) Systematize the conceptual hydrogeological model of the Katari River basin for its integration with the validated surface hydrological model.

This study has allowed us to analyze the operation model of the Katari aquifers, where all hypotheses and data obtained are justified by consistent calculations. Although the hydrogeological model is considered correct, the information gaps found during the conceptualization process, as well as the results obtained through numerical modeling have shown that it is necessary to go deeper into certain aspects (sampling points inventory, improve hydrochemical monitoring, know the geology in depth in greater detail, among others).

This conceptual and numerical model, integrating the information available in a single platform, has made it possible to define the evaluation of risks or environmental impacts of the area and provide a frame of reference for other studies or more detailed models.
Improving lignin quantification and characterization in seawater using spectral liquid chromatography and PARAFAC2
Authors: Jensen Anders Dalhoff Bruhn , Wünsch Urban , Osburn Christopher Lee , Stedmon Colin Andrew
Published: March 2022

Lignin, a macromolecule found in all vascular plants, can be used as a biomarker for terrestrial dissolved organic matter in the ocean. Measuring lignin in the ocean can help us quantify the supply to and fate of terrestrial carbon in the ocean. Lignin analyses in aquatic samples quantify phenolic products after cupric oxidation using gas or liquid chromatography, with detection either by mass spectrometry or UV-Vis spectroscopy. Mass spectrometry yields low detection limits and high specificity, but requires specialized and expensive instrumentation. In contrast, liquid chromatography coupled with UV-Vis spectroscopy is more readily available and cheaper to operate, but traditionally suffers from lower specificity due to overlapping signals of the bulk organic matter background.

This study demonstrates a new approach of UV-Vis spectroscopic detection coupled to high-performance liquid chromatography (HPLC) that circumvents common issues and improves the detection limit by a factor of 10. This improvement is accomplished by using the second derivative of the chromatogram and applying a modified parallel factor analysis (PARAFAC2). PARAFAC2 tolerates subtle remaining chromatogram shifts in retention time between samples and successfully separates spectra of co-eluting signals. The isolation of spectra based on this machine learning approach improves both lignin phenol identification and the accuracy of their quantification. The approach developed automates the analysis of chromatograms and considerably reduces the water volumes required, improving the applicability of HPLC-UV-Vis for lignin characterization, which may increase the feasibility for widespread use.
Ancient Tillandsia landbeckii dune ecosystems and their potential to reveal past variations in coastal fog moisture during the Holocene in the Atacama Desert
Authors: Latorre Claudio , Contreras Sergio , Jaeschke Andrea , Garcia Juan Luis , del Río Camilo
Published: March 2022

Tillandsia landbeckii is a bromeliad that inhabits the hyperarid coast of the Atacama Desert where it survives solely on moisture and nutrients from fog. It does so by constituting a unique dune ecosystem that maximizes its fog capture potential as well as preserving layers of buried tillandsia plants. These buried layers can survive over multiple millennia and here we present data based on stratigraphic, radiocarbon, stable isotopes, and leaf wax analyses that we are applying to these ancient leaves and stems to reconstruct past variations in fog moisture and nutrient cycling. Some of the oldest buried layers date back to >10,000 14C yrs BP and our results show that both d15N and leaf waxes are capable of tracking variations in moisture changes although we observed significant variation in d15N values across living plants which may be due to the plants' age. Past variations in fog likely track variations in large-scale synoptic climate features such as the height of the Marine Boundary Layer and the strength of the Southern Pacific Anticyclone.
Hydrothermal Manganese mineralization in a Triassic back-arc rift-related volcaniclastic succession of the Cycladic Blueschist Unit, Greece
Authors: Stouraiti Christina , Lozios Stylianos , Soukis Konstantinos , Mavrogonatos Constantinos , Tsikos Harilaos , Voudouris Panagiotis , Wang Hao , Zamparas Christoforos , Kollias Konstantinos
Published: March 2022

The Cycladic Blueschist Unit (CBU) of the Aegean (Greece) contains several occurrences of metamorphosed Manganese mineralization within a Triassic volcaniclastic sequence. The latter includes quartz-mica schists intercalated with bimodal metavolcanics and blue-grey marble layers. SHRIMP U-Pb zircon dating has documented the Triassic age (~242 Ma) of the volcanic rocks. Herein we revisit the Mn metallogenic system of the CBU through an extensive study of Mn mineralization at Varnavas area, Northern Attica, and a similar occurrence at central Andros Island (Mparades hill). Manganese mineralogy at both localities is manifested in a typical high-P metamorphic silicate assemblage dominated by piemontite, spessartine garnet, and minor pyroxmangite (rhodonite). At Andros, Mn-rich subdomains contain brecciated braunite micronodules. The preservation of similar nodular form is documented from Varnavas, comprising dominant todorokite, lesser hollandite, pyrolusite, and minor Mn-bearing hematite. The contrasting Mn oxide mineralogy at the two sites is tentatively interpreted as the result of locally incomplete reduction of precursor Mn(IV) phases during metamorphism. Common geochemical characteristics of the Mn-rich rocks include low transition metal concentrations; positive-sloping, PAAS-normalized REE spidergrams; positive Ce anomalies of variable magnitude across individual samples; and high As, Ba, Pb. The geochemical variability recorded is ascribed to the varying mixing of a hydrothermal-sourced, hydrogenous metalliferous component that precipitated penecontemporaneously with the deposition of the host tuffs. The primary Mn precipitates are thought to have been in the form of tetravalent Mn assemblages, which may locally be partially preserved through metamorphism, as appears to be the case in the Varnavas occurrence. All these reveal the interplay between the felsic/intermediate back-arc volcanism and associated hydrothermal activity and the Mn mineralization within the rift setting of the CBU domain.