bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of extreme precipitation and temperature events during El Niño Southern Oscillation in the Colombian Andes
Authors: Acero Isabel C. , Vieira Sara C.
Published: March 2022

Extreme precipitation and temperature events (EPTE) cause devastating impacts to ecosystems and society. The diversity of climates around the world does not allow a single definition of extreme events given the multiplicity of conditions in which each event develops. In regions of complex topography, interactions with vegetation have as a result numerous atmospheric circulation patterns and the existence of various phenomena at different spatial and temporal scales, which impedes homogeneity of distribution, frequency, and intensity of extreme events. It is known that El Niño Southern Oscillation (ENSO) influences the interannual variability of precipitation and temperature in different regions around the world. However, it is not clear how this phenomenon interacts with the frequency and intensity of EPTE in regions with complex topography gradient and a diversity of climates. Here we focus on the Colombian Andes mountain range in northern South America because it occupies a quarter of the territory, gathers most of the socio-economic development, and concentrates the majority of the country´s population. In this context, we use statistical analysis to characterize EPTE during La Niña, El Niño, and neutral years. In this work, we also compare the frequency and intensity of EPTE between La Niña and neutral years and El Niño and neutral years. Unlike other studies, we want to know if there is any pattern of increase or decrease of EPTE when an ENSO phase is active. We discuss the months in which there is an increase or decrease in EPTE according to the interannual variability of precipitation and temperature, as well as the months in which there is a significant relationship between the sea surface temperature of the Niño 3.4 region with precipitation and temperature. Our results show that the highest intensities of extreme precipitation events occur in the rainy seasons March-April-May and September-October-November. Also, the highest frequency of extreme precipitation events occurs between December and March for both the 95th and 99th percentile. The difference analysis showed that during El Niño and La Niña periods, extreme precipitation events are more intense than in neutral years. Additionally, the frequency of events is higher during El Niño, but their localization is variable in time and space. The behavior of temperature extremes is more marked since the most intense events occur during El Niño from February to September, and the highest frequency of extreme events occurs between April and September and varies throughout the year in the Andes region according to the active phase of ENSO. These results provide a basis for the design of adaptation and mitigation policies in the face natural variability and climate change, and for improving hydrometeorological forecasts.
Thermo-mechanical effects of dyke host rocks in response to turbulent magma flow
Authors: Patel Rahul , Sarma D Srinivasa , Panda Aurovinda
Published: March 2022

We study the thermal erosion and mechanical fragmentation of dyke host rocks using a thermodynamical and fluid-mechanical approach. It is inferred that the latent heat of magma mainly causes the thermal damage of dyke host rocks and encourages thermal erosion. The application of fluid-dynamical shear stress on the dyke walls induced by turbulence magma flow results in mechanical fragmentation., We calculated the Reynolds number to confirm these findings to decipher the nature of magma flow through the dykes. The estimated Reynolds number for 30 dykes is in excess of 2000 suggesting that magma ascends turbulently through the dykes. The turbulence of magma flow provides additional energy to derive thermal erosion and mechanical fragmentation.  In order to better understand the thermo-mechanical effect of dyke host rocks, we used the mass conservation principle. Equations for mass conservations are derived to better explain the complex interactions between magma and host rock. Heat transfer, magma flow rate, magma flow velocity, and host rock melting are calculated. The presence of xenoliths in the dykes is primary evidence that the dykes have been mechanically fragmented. We present an integrodifferential equation to understand the kinematic of mechanical fragmentation and size of xenoliths varies due to secondary Collison within a dyke. Presented results are useful to understand the nature of magma, dyke host rock melting, and magma evolution.

Key words: Thermal erosion, mechanical fragmentation, turbulent magma flow, dykes
Automatic Detection of Interplanetary Coronal Mass Ejections
Authors: Ruedisser Hannah , Windisch Andreas , Amerstorfer Ute V. , Amerstorfer Tanja , Möstl Christian , Reiss Martin A. , Bailey Rachel L.
Published: March 2022

Interplanetary coronal mass ejections (ICMEs) are one of the main drivers for space weather disturbances. In the past,
different machine learning approaches have been used to automatically detect events in existing time series resulting from
solar wind in situ data. However, classification, early detection and ultimately forecasting still remain challenges when facing
the large amount of data from different instruments. We propose a pipeline using a Network similar to the ResUNet++ (Jha et al. (2019)), for the automatic detection of ICMEs. Comparing it to an existing method, we find that while achieving similar results, our model outperforms the baseline regarding GPU usage, training time and robustness to missing features, thus making it more usable for other datasets.
The method has been tested on in situ data from WIND. Additionally, it produced reasonable results on STEREO A and STEREO B datasets
with less input parameters. The relatively fast training allows straightforward tuning of hyperparameters and could therefore easily be used to detect other structures and phenomena in solar wind data, such as corotating interaction regions.
The impact of liquid organic fertilization and associated application techniques on N2, N2O and CO2 fluxes from agricultural soils
Authors: Grosz Balázs , Kemmann Björn , Burkart Stefan , Petersen Søren O. , Well Reinhard
Published: March 2022

Prediction of liquid manure effects on N transformations in soils and associated N2O and N2 fluxes is poor because previous investigations mostly excluded N2, the end product of denitrification. We address the questions, (1) how liquid manure fertilization and its application technique impact N2, N2O and CO2 fluxes from agricultural soil, and (2) how the water, mineral N and dissolved organic carbon (DOC) content of the manure amended soil change between the soil layers. A sandy arable soil was used in a 10 days laboratory incubation at constant 15oC, constant 40% and 60% water-filled pore space (WFPS) and amended with and without artificial slurry in three manure treatments (control, surface-applied, injected). N2O and CO2 fluxes were quantified by gas chromatography. N2 and source-specific N2O flux was quantified by isotope-ratio mass spectrometry. At 5th and 10th day, depth distribution of moisture, NH4+, NO3-, DOC, pH and 15N enrichment of NO3- was determined with destructive sampling. The N2+N2O flux of the surface-applied and injected 40% WFPS treatments were 75% and 110% higher than the control and at 60% WFPS treatments were more than 610% and 1690% higher than the control. The product ratio of denitrification showed enhanced share of N2 to the N2+N2O flux in the manure treatments, which we attribute to hot-spot dynamics of the manure layers. Our data demonstrate how the dynamics of moisture, labile C, NH4+-N, formation of NO3--N by nitrification and pH following manure surface application or injection interact and result in N2O cycling by various pathways. The data-set can thus be used to evaluate and further develop models to predict denitrification and respiration processes of the manure-soil hot-spots. Further progress in unravelling and modeling manure induced hot-spot dynamics can be achieved if temporal and spatial resolution of our measurements is improved and additional techniques to determine O2 distribution and distinguish gross N transformations and their gaseous N fluxes are included.
Aviation-induced changes in cirrus clouds over Europe during COVID-19 and in a ten-year period before COVID-19 
Authors: Li Qiang , Groß Silke
Published: March 2022

Aviation affects the Earth’s radiation budget through a combination of multiply processes which warm the atmosphere. Linear contrails and contrail cirrus induced by water vapor and soot emissions from air traffic in the upper atmosphere are expected to contribute a large part of the climate impact of avation. Furthermore, contrails cause a significant increase in cirrus optical thickness as well as an indirect effect on the microphysical properties of naturally formed cirrus clouds. During the first lockdown in April 2020, air traffic over Europe was significantly reduced to about 80% compared to the year before. This unique situation provides a good opportunity to study the effect of air traffic on cirrus. Based on the analysis of the spaceborne lidar measurements with CALIPSO, we found a significant reduction in the particle linear depolarization ratio (PLDR) of cirrus clouds measured in April 2020 compared to the previous years 2014-2019 under normal conditions, especially at colder temperatuers (T < -50oC). However, we note that civil aviation over Europe before the COVID-19 pandemic (i.e., before March 2020) grew strongly in terms of CO2 emission and flight densities, e.g. on average by 233 MTon/year over Germany, over the past years (2010-2019, especially 2013-2019, source: EUROCONTROL). In order to study the aviation effects of cirrus properties in a longer period (with, of course, milder change in air traffic than the case due to the COVID lockdown), we further extend our analysis to all the observations from Mar. 2010 to Feb. 2020. We found a long-term trend of 0,0087/year (~2.4% per year) in PLDR for all the cirrus observations (day+night) and a trend of 0.0107/year for only the day-time observations at altitudes between 6 and 13 km. In addition, seasonal variations of PLDR are also drived showing higher PLDR-values in winter than in summer for all the measurements as well as for the measurements in different altitude bins. In the end, we compared the background meteorological conditions including the ambient temperature, relative humidity, and vertical updrafts determined with ECMWF and analyzed the correlation between PLDR and the corresponding CO2 emissions as a proxy of air traffic densities.

Key words: CALIPSO; Cirrus cloud; Lidar; Depolarization ratio; PLDR; COVID-19
Exploring the SZ lossy compressor use for the XIOS I/O server
Authors: Yepes-Arbós Xavier , Di Sheng , Serradell Kim , Cappello Franck , C. Acosta Mario
Published: March 2022

Earth system models (ESMs) have increased the spatial resolution to achieve more accurate solutions. As a consequence, the number of grid points increases dramatically, so an enormous amount of data is produced as simulation results. In addition, if ESMs manage to take advantage of the upcoming exascale computing power, their current data management system will become a bottleneck as the data production will grow exponentially.

The XML Input/Output Server (XIOS) is an MPI parallel I/O server designed for ESMs to efficiently post-process data inline as well as read and write data in NetCDF4 format. Although it offers a good performance in terms of computational efficiency for current resolutions, this could change for larger resolutions since the XIOS performance is very dependent on the output size. To address this problem we test the HDF5 compression in order to reduce the size of the data so that both I/O time and storage footprint can be improved. However, the default lossless compression filter of HDF5 does not provide a good trade-off between size reduction and computational cost. 

Alternatively, we consider using lossy compression filters that may allow reaching high compression ratios and enough compression speed to considerably reduce the I/O time while keeping high accuracy. In particular, we are exploring the feasibility of using the SZ lossy compressor developed by the Argonne National Laboratory (ANL) to write highly compressed NetCDF files through XIOS. As a case study, the Open Integrated Forecast System (OpenIFS) is used, an atmospheric general circulation model that can use XIOS to output data.
Preliminary fracture analysis from the frontal most exposure of a major roof thrust in the Eastern Himalaya: Insights from the Ramgarh thrust, Sikkim Himalaya.
Authors: Jk Ammu , Bhattacharyya Kathakali
Published: March 2022

Shear zones associated with major thrust faults generally record overprinting of deeper crustal deformation signatures by shallower crustal signatures due to faults climbing up-section along the transport direction. In this study, we investigate the deformation signatures related to the shallow crustal conditions on one such major thrust, the Ramgarh thrust (RT) from Sikkim Himalayan Fold Thrust Belt (FTB). RT is an intermediate crustal thrust that has recorded a translation of ~58-65 km and overprinting of deformation structures. RT acts as the roof thrust of Lesser Himalayan duplex, hence got reactivated several times, and records a long deformation history.

In Sikkim Himalaya, the frontal most exposure of the RT is near Setikhola (N26° 56.178’, E88° 26.607’) as ~57m thick shear zone that exposes the lower Lesser Himalayan Daling quartzite and phyllite in the hanging wall over Gondwana sandstone in the footwall. The mean bedding is oriented ~72°, 298°, and the mean dominant cleavage is ~ 70°, 305°. The outcrop forms the overturned forelimb of a fault-bend antiform. The outcrop is strongly fractured. Based on the angular relationship with respect to the bedding, three sets of fractures were identified. Low angle fractures (< 30° to bedding) constitute ~20.23 %, moderate (30° – 60° to bedding) and high angle fractures (60°- 90° to bedding) constitute ~39.88% of the total fracture population. The fractures are uniformly distributed throughout the stretch of the shear zone. Daling quartzites accommodate more number of fractures than the phyllites. Preliminary investigation indicates that the thicker beds have higher fracture intensity than thinner beds. Few of the fractures were identified as opening mode fractures based on their association with the plumose structures. ~ 17.3% of the total measured fractures records slickenline lineations. These shear fractures reveal two clusters on the stereonet (Set 1: ~90°, 098°; Set 2: ~77°, 331°). They have a dihedral angle of ~54⁰ and set 1 and set 2 are oriented ~ 27⁰ and ~ 32⁰ to the bedding respectively. Based on preliminary analysis, the local maximum principal stress (σ1) is oriented sub-horizontally with a SSW trend. Interestingly, this estimate is in agreement with the current global stress orientations from the Eastern Himalaya, where σ1 is near horizontal and trends NNE – SSW (Larson et al., 1999).
Slope fans and aprons dominated by supercritical bedforms:  topographic and feeding system controls (Southeastern Tyrrhenian Sea) 
Authors: Scacchia Elena , Tinterri Roberto , Gamberi Fabiano
Published: March 2022

In the marine environment, turbidite supercritical bedforms have been widely reported from channel-axis and overbank wedges. On the contrary, their dominance in the make-up of fans and apron, apart from local areas such as channel mouths, is at present not recognized. However, since it has been postulated that turbidity currents reach the supercritical conditions for slope > 0.5°, submarine slopes should contain abundant supercritical flow deposits. Here, we provide a review of different types of slope fans and aprons dominated by supercritical bedforms, based on examples from the modern seafloor. We compare depositional elements located in different intraslope basins of the Tyrrhenian Sea, through high-resolution bathymetry, chirp subbottom section and, where available cores. The variable geological context results in axial and transvers slope fans with highly variable sizes (few to tens of kilometres) and geometries, dependent upon the erosive and/or depositional processes involved, as well as the seafloor topography of the area. In particular, we have recognized two types of lobe-shaped deposits characterized by supercritical bedforms: channel-attached fans and detached aprons. The first ones are connected to a canyon-channel system and develop on slope gradients of 0.5° to 1.2°, display small-scale bedforms (wavelength of about 150 m and height < 10 m), with upslope asymmetric or symmetric cross-sections, interpreted as cyclic steps and antidunes. According to the amplitude of the reflections, cores, and to the bedform aspect ratio, the channel-attached fans are interpreted to be composed of coarse-grained sediments. Our examples highlight that cyclic steps and antidunes dominate the channel-attached fans both in axial and lateral portion while scours mark topographic changes such as breaks in slope or laterally confined areas. Detached aprons develop from the un-incised shelf edge on steep slopes of about 1.2° to 3° and are composed by large-scale bedforms (wavelength of about 500 m and height of about 5 m) mainly upslope asymmetric, associated with cyclic steps. The low amplitude of the seismic reflections suggests the fine-grained nature of the aprons. This study shows that there are significant differences in the distribution and character of supercritical bedforms in slope settings according to the type of feeding system, the degree of flow confinement and the seafloor topography. The analysis of the downslope evolution of turbidity currents, and of the character of associated bedforms in deep-water systems can contribute new perspectives to refine our models of deep-sea depositions.
Heat transport by flow through rough rock fractures
Authors: Klepikova Maria , Méheust Yves , Roques Clément , Linde Niklas
Published: March 2022

Fracture surface topography exhibits long-range spatial correlations resulting in a heterogeneous aperture field. This leads to the formation, within fracture planes, of preferential flow channels controlling flow and transport processes. We have investigated numerically the influence of the statistical properties of the aperture field and upscaled hydraulic behavior on heat transport in rough rock fractures with realistic geometries. Similarly to the rough fracture's hydraulic behaviour, we find that its heat transport behaviour deviates from the conventional parallel plate fracture model with increasing fracture closure and/or decreasing correlation length.  We demonstrate that the advancement of the thermal front is typically slower in rough fractures compared to smooth fractures having the same mechanical aperture. In contrast with previous studies that neglect temporal and spatial temperature variations in the rock matrix, we find that the thermal behavior of a rough-walled fracture can, under field-relevant conditions, be predicted from a parallel plate model with an aperture equal to the rough fracture's effective hydraulic aperture. The practical implication of our finding is that thermal exchanges at the scale of a single fracture is controlled by the effective hydraulic transmissivity. Provided that thermal properties of the host rock are known, this implies that (1) geothermal efficiency can be computed at field sites using hydraulic characterization alone, and predicted using well-known low-dimensional hydraulic parameterizations in terms of effective hydraulic properties and (2) heat tracer tests are reliable for inferring effective fracture transmissivity.
Influence of post-drought climate sensitivity deviations on secondary growth in European beech (Fagus sylvatica L.)
Authors: Leifsson Christopher , Buras Allan , Rammig Anja , Zang Christian
Published: March 2022

Extreme drought events will have an increasing influence on forest ecosystems and services in the course of climate change. It is thus pivotal to understand their direct impacts and subsequent recovery patterns. Drought impacts are often reported as changes in net primary productivity (NPP) related to impact severity. However, because NPP integrates over all physiological processes, variability in NPP alone cannot explain internal mechanisms.

Due to temporally variable growing conditions, climate-growth relationships are naturally non-stationary on longer time scale. On shorter time scales, extreme drought events are considerable perturbations that likewise alter the climate sensitivity of growth, corresponding to physiological impacts caused by drought. Therefore, post-drought changes in the climate sensitivity of growth serves as a potential avenue of studying physiological impacts. Decoupled climate-growth relationships would be expected in the case of damage on the hydraulic system or reallocation of carbon to rebuild foliage. Conversely, tightened coupling would be expected in the case of stricter growing conditions as per the law of the minimum or carbon reallocation towards increased xylogenesis. 

Because experimental ecophysiological studies are labour and cost intensive, they are typically limited in space and time. Meanwhile, climate-growth relationships derived from tree-ring widths (as an approximation for variability in NPP) and high-resolution climate products are easily accessible on regional to global scales. By finding common post-drought responses in climate sensitivity of tree-growth for trees grouped by abiotic and biotic factors it is possible to analyse physiological impacts on large scales, thus effectively enhancing our understanding of the underlying mechanisms that result in quantified impacts on NPP.

Here, we aim to find intraspecific differences in post-drought climate-growth relations for the ecologically and economically important European tree species European beech (Fagus sylvatica L.). Using a European-wide dataset of tree-ring widths, the European Beech Tree-Ring Network (EBTRN), we compute post-drought changes in climate-growth relationships – climate sensitivity deviations – in addition to direct and lagging impacts on absolute tree-ring derived growth. Preliminary analyses indicate a complex connection between growth recovery rates and diverging post-drought climate sensitivity deviations, in turn shaped by growing condition factors.
First detailed air pollution analyses by assimilating UAV observations with EURAD-IM
Authors: Erraji Hassnae , Franke Philipp , Düsing Sebastian , Schuldt Tobias , Buchholz Marcel , Schlerf Andreas , Bretschneider Lutz , Lampert Astrid , Wahner Andreas , Lange Anne Caroline
Published: March 2022

In atmospheric science, Unmanned Aerial Vehicles (UAV) are relatively new technologies that started to be used recently for the assessment of atmospheric composition, bringing many opportunities to improve air monitoring. Within the MesSBAR (automatisierte luftgestützte MESsung der SchadstoffBelastung in der erdnahen Atmosphäre in urbanen Räumen/Automated airborne measurement of pollution levels in the near-ground atmosphere in urban areas) project, new drones carrying trace gas and aerosol instruments have been developed to measure near-surface vertical profiles of atmospheric pollutants with high temporal resolution while being flexible, inexpensive, and able to perform measurements close to the emission sources.

The use and benefit of the assimilation of such high-frequency observations in a regional chemical transport model have not been studied yet. However, it presents a possible promising opportunity to improve air quality forecasting as in particular, it supports to receive a better representation of the pollutants in the planetary boundary layer.

In this work, we evaluate the impact of the assimilation of UAV observations on the analysis and forecast of traces gases and aerosols. The observations used resulted from a series of drone measurements carried out close to a motorway in Wesseling, Germany, from 21 to 23 September 2021 as part of the MesSBAR project. We perform high-resolution analyses (1 km x 1 km spatially and ~20 s temporally) assimilating UAV profiles using the 4D-Var data assimilation technique in the EURopean Air pollution Dispersion - Inverse Model (EURAD-IM). The results are compared in the first place to the operational EURAD-IM forecast without assimilation to evaluate the impact of the UAV observations on the analysis. Then, the analysis is compared to ground-based observations measured during the campaign and to other independent data to evaluate the analysis accuracy. The improvement in the analysis obtained by UAV observations with respect to emissions factor optimization is assessed and discussed.
Trade-offs between water needs for food, utilities, and the environment—a nexus quantification at different scales
Authors: de Vos Lotte , Biemans Hester , Doelman Jonathan C , Stehfest Elke , van Vuuren Detlef P
Published: March 2022

With a growing population and a changing climate, competition for water resources in the water-energy-food (WEF) nexus is expected to increase. In this study, competing water demands between food production, freshwater ecosystems and utilities (energy, industries and households) are quantified. The potential trade-offs and related impacts are elaborated for different SSP scenarios with the integrated assessment model IMAGE, which includes the global vegetation and hydrology model Lund-Potsdam-Jena managed Land (LPJmL). Results for the 2045–2054 period are evaluated at the global scale and for a selection of 14 hotspot basins and coastal zones. On the global scale, we estimate that an additional 1.7 billion people could potentially face severe water shortage for electricity, industries and households if food production and environmental flows would be prioritized. Zooming in on the hotspots, this translates to up to 70% of the local population. Results furthermore show that up to 33% of river length in the hotspots risks not meeting environmental targets when prioritizing other water demands in the nexus. For local food production, up to 41% might be lost due to competing water demands. The potential trade-offs quantified in this study highlight the competition for resources in the WEF nexus, for which impacts are most notably felt at local scales. This emphasizes the need to simultaneously consider different dimensions of the nexus when developing scenarios that aim to achieve multiple sustainability targets.
Evaluation of canopy cover dynamics using phenological and productivity indices: the case of Mediterranean oak forests affected by dieback
Authors: Castellaneta Maria , Rita Angelo , Borghetti Marco , Ripullone Francesco
Published: March 2022

Increasing aridity, primarily driven by higher temperatures and lower precipitation, will threaten the stability and health status of Mediterranean forest ecosystems. Vegetation phenology has been globally acknowledged as a key tool to track the timing of seasonal plant and animal activities as well as changes in the forest ecosystems in response to climate change. In this study, we sought to address the phenological behavior of Mediterranean forest stands exhibiting evident decline symptoms. We investigated how phenological and productive indices for Quercus cerris, Quercus pubescens, and Quercus frainetto stands would be able to reflect the seasonal vegetative dynamics of forests affected by dieback, through a multi-scale and multi-temporal approach. To this, we compared nearby stands showing different vigor, i.e., dieback vs non-dieback, assessed as growths decline, elevated crown transparency, and rising tree mortality rate. For this purpose, phenological metrics of greenness (NDVI, Normalized Difference Vegetation Index) and phenological (PPI, Plant Phenology Index) spectral indices were derived from either MODIS Terra and Aqua or Sentinel 2 satellites. Our results indicated peculiar site-specific phenological patterns. We observed that dieback forest stands - characterized by a high percentage of trees showing canopy defoliation - exhibited different phenological behavior compared with non-dieback stands. Shifts in length of growing season and seasonal amplitude among dieback and non-dieback stands occurred, that probably affect seasonal productivity. Furthermore, climatic fluctuations may have also affected such phenological patterns. Aligning proxies for the phenological and productive status of forest vegetation may improve our understanding of the responses of dieback forests to the changing climate, mainly in the Mediterranean region.
Tracing 100 years of morphological development of the Sankt Peter-Ording sand, a barrier beach system in the North Frisian Wadden Sea.
Authors: Soares Clayton , Herrling Gerald , Winter Christian
Published: March 2022

Sankt Peter-Ording is the only mainland beach system of the Wadden Sea between Den Helder in the Netherlands and Blåvandshuk in Denmark. The initiation and morphological evolution of this barrier system was reconstructed based on historical sea charts and literature. It was documented how a narrow Sankt Peter-Ording sand bar first appeared between 1920 and 1925. In the 1960’s a second bar attached to the north end and fully merged around 1994. Since its arrival the shoreline has been moving landward, permanent foredunes (today as high as 10m) have formed since the 1970’s and a salt marsh has formed behind the barrier. Early mapping campaigns show that the beach has grown over three times in area from approximately 4sq. km in 1943 to 12 sq. km in 2016. The retreat of the central beach is accompanied by accumulation along the Northern and Southern heads of the beach. The landward movement of the central beach is ~7m/a, while the north head has been growing at ~25m/a in the northerly direction. Extensive accumulation was identified in the South head of the beach, which moved ~2km in the SE direction since 1949 and roughly 400m in width. Coast parallel bedforms in the foreshore and at the south head of the beach ranged from 50-300m in length. Analysis of foreshore bathymetry reveals a prevalent SE direction of sediment movement. A foreshore bar system and channel have been moving at an average celerity of ~30m/a in the S-SE direction. Schematic spatial impression on the sediment transport pathways of the system is evaluated from the morphological development.
Ancient foraminiferal DNA: A new paleoceanographic proxy.
Authors: Pawłowska Joanna , Pawłowski Jan , Zajączkowski Marek
Published: March 2022

Until now, the assessment of past climate impacts on marine biodiversity was based exclusively on taxa preserved in the fossil record. However, most marine species do not leave any fossilized remains that could be identified morphologically. Hence, our current view of the evolution of marine biodiversity is fragmentary and limited to a few skeleton-bearing taxa only. Recent advances in environmental genomics have the potential to change this situation radically. In particular, the analysis of environmental DNA, defined as genetic material obtained directly from environmental samples (soil, sediment, water, etc.), has proven to be an efficient method to monitor biodiversity changes over time and space. A demonstration that DNA can be preserved in marine sediments across geological timescales opened new avenues to using ancient DNA (aDNA) in paleoceanographical studies. Numerous studies report the preservation of DNA in marine sediments over the tens to hundred thousand years, showing that the marine sediments are an underexplored DNA repository that can be used to assess marine biodiversity.

Our research on foraminiferal aDNA illustrated the presence of aDNA in Late Quaternary sediments in the Nordic Seas. Our studies revealed extremely diverse foraminiferal assemblage, with a diversity that exceeds what is recorded in the fossil record. In particular, the aDNA studies revealed a huge diversity of non-fossilized monothalamous foraminifera, which comprise several new potential proxy species. We distinguished monothalamous taxa that are potential indicators of changes in glacial activity, sea-ice coverage, and productivity. Although microfossil and aDNA records are complementary rather than overlapping, in combination, they reveal more detailed information than inferred from the individual approach. Furthermore, our results suggest that molecular analysis at finer levels can provide valuable information about the occurrence of different foraminifera genotypes over time. These genotype-level changes can be related to environmental conditions, implying that the genotypes have different ecological preferences and could potentially be used as paleoceanographic proxies in the future.

The analysis of aDNA requires various precautions to avoid contamination when isolating aDNA from environmental samples, and there is a need to consider several limitations resulting from the degraded nature of DNA and potential technical biases. Although, the advantage of paleogenomics to provide complementary insight into biodiversity changes beyond what is shown by fossil records is indisputable. The ancient DNA approach may provide a powerful means to reconstruct paleoenvironments more comprehensively and better understand past climatic and environmental changes.

The project was funded by the National Science Center grant no. 2018/31/B/ST10/01616
Coupling and decoupling of carbon, oxygen, and nitrogen in the Elbe Estuary
Authors: Norbisrath Mona , Pätsch Johannes , Dähnke Kirstin , Sanders Tina , Schulz Gesa , van Beusekom Justus E. E. , Thomas Helmuth
Published: March 2022

The Elbe Estuary and its biogeochemistry are strongly influenced by tidal cycles of the North Sea, high nutrient and organic matter loads from the catchment area, and dredging of the navigation channel to maintain the connection between the North Sea and Germanys largest seaport in Hamburg.

Due to large phytoplankton blooms upstream of the port, the input of organic matter is high and provides high metabolic activity within and downstream the Hamburg port.

Here, we combined carbon, oxygen, and nitrogen data to elucidate their relationship and distribution along the Elbe Estuary. We used a box model approach to balance the budgets of dissolved inorganic carbon (DIC), oxygen (O2), and nitrogen in form of nitrate (NO3-). To complete carbon and oxygen, we included atmospheric exchange of carbon dioxide (CO2) and O2.

DIC generation and O2 consumption reveal the highest metabolic activity in the Hamburg port area, decreasing downstream. In contrast, NO3- budgets are stable along the estuary, indicating a strong decoupling of carbon and nitrogen in the Elbe Estuary. This decoupling can be explained by anaerobic processes such as denitrification in the port area, but it also implies lateral nitrogen sources further downstream.
Assessment of the Antarctic ice-sheet response to ice-shelf collapse as a function of the friction law employed
Authors: Pérez-Montero Sergio , Blasco Javier , Robinson Alexander , Montoya Marisa , Alvarez-Solas Jorge
Published: March 2022

Sea-level rise projections under climate change exhibit large uncertainty related to the contribution of ice sheets. A major source of uncertainty is the Antarctic Ice-Sheet (AIS) due to the marine-based nature of the West Antarctic Ice-Sheet (WAIS). Part of the WAIS is grounded under sea level and thus in contact with the surrounding ocean via the floating ice shelves. Melting of ice shelves does not directly contribute to sea level rise but it modulates the ice flow towards the sea by controlling the discharge through the grounding line. However, the processes that regulate the dynamics are not fully well understood and represented in state-of-the-art models due to the complexity of the various feedbacks involved. In addition, the basal friction or sliding law that should be employed is not well known. In this context arose the Antarctic BUttressing Intercomparison Project (ABUMIP, Sun et al., 2020) with the aim of studying the response of the AIS to a sudden and maintained collapse of its ice shelves. Here we show the results obtained while performing experiments extending those of Sun et al., (2020) with the thermomechanical ice-sheet model Yelmo and assessing the effect of using different friction laws.
Complex seismicity patterns accompanying the 2021 volcanic eruption at La Palma, Canary Islands, Spain
Authors: del Fresno Carmen , Cesca Simone , Domínguez Cerdeña Itahiza , Díaz-Suarez Eduardo , Milkereit Claus , Valenzuela Carla , López-Díaz Rubén , Dahm Torsten , López Carmen
Published: March 2022

A moderate seismicity accompanied the dike intrusion which preceded the 2021 volcanic eruption at La Palma, Canary Islands, Spain. Nevertheless, the largest magnitudes were recorded during the eruption, from September 19th to December 13th, 2021. This volcanotectonic activity accompanied the upward magma transfer to feed the eruption and provides important clues to the understand the feeding system geometry, as we are dealing with the first fully monitored eruption in the island. Seismicity during the eruption displayed a stable bimodal spatial distribution, with hypocenters clustering at two, well separated depth intervals. A shallower seismic cluster was active beneath the central area of Cumbre Vieja  ~10-14 km depth, starting by September 27, just after a short quiescence of about 3 hours in the tremor signal and with peaks of intensification rates in mid and late November. A deeper and larger cluster (~33-39 km) extended further to the Northeast. Here, the activity started with some delay on October 5th and the cluster was mostly active over October and November 2021, reaching a peak magnitude mbLg 5.1 November 19th, 2021, the largest earthquake of the whole seismic sequence. In this study, we use a variety of seismological methods to resolve hypocentral and centroid location at the two clusters, as well as full moment tensors for 156 earthquakes, including largest ones at each cluster. The hypocentral relocation of 7150 earthquakes reconstructs the geometry of the active seismogenic structures, resolving small-scale details within each of the two clusters. The centroid moment tensor inversion resolves different families of moment tensors in each cluster including earthquakes with almost reversed focal mechanism that respond to local stress perturbations introduced by the magma rise through a complex path and multiple magmatic reservoirs. The source studies are complemented by a temporal analysis of the families based on waveform characterization, which allows to reconstruct the timeline of the magma transfer and seismogenic processes. Our seismological analysis provides details of seismicity accompanying the volcanic unrest at La Palma and documents the evolution of seismogenic processes in response to the rise of magma batches through the complex plumbing system.

 
Combining geoelectric field modelling and differential magnetometer data to validate GIC modelling in the UK High voltage power transmission grid
Authors: Huebert Juliane , Beggan Ciaran , Richardson Gemma , Gomez Perez Natalia , Thomson Alan
Published: March 2022

Geomagnetically induced currents (GICs) have been identified as a hazard to the UK power grid and the security of electricity supply during severe geomagnetic storms. In order to monitor, model and forecast GICs, sophisticated models of the ground electric field and the network topology are required. We present a detailed analysis of differential magnetometer (DMM) and magnetotelluric (MT) data in the UK that allow the verification and validation of our network model for the UK power transmission grid. Combining the observation of line GICs measured with DMM in the past three years and the MT impedance tensor estimated at several locations in the UK shows an excellent fit of prediction and observation of GICs when using realistic modelled ground electric fields. This validates our whole network model allowing us to use it with confidence for real time and forecasting as well as extreme event analysis.
Noise-based estimation of local seismic amplification in an industrialized area of the French Rhone Valley
Authors: Gisselbrecht Loïc , Froment Bérénice , Boué Pierre
Published: March 2022

Shallow sedimentary layers have a strong impact on seismic motion. These so-called site effects may be responsible for dramatic ground motion amplification and increase the duration of shaking when an earthquake occurs. The quantification of such amplification effects for specific sites might be challenging to carry out in low-to-moderate seismicity regions where moderate to large earthquakes have long return periods. Therefore, methods based on background ambient noise might be of great interest for these areas.

In this study, we investigate the potential of ambient noise in ground motion amplification assessment through SSRn (noise-based Standard Spectral Ratio) and SSRh (hybrid Standard Spectral Ratio, Perron et al., 2018) computation. We continuously recorded ambient noise from February to March 2020 on a 400-sensor seismic array covering an area of about 10 x 10 km in the Tricastin industrial region (French Rhone Valley) where critical facilities are located. This area is located on a very elongated valley, filled with Pliocene sediments (sands and clays), that was dug during the Messinian Salinity Crisis in Cretaceous sandstones and limestones. The strong lithological contrast between the sedimentary filling and the bedrock, as well as the valley's incised geometry, is prone to generate strong and complicated site effects.

Previous studies have shown that SSRn is not able to reproduce earthquake-based SSR amplification factor for frequencies higher than 1 Hz. This disagreement may be explained by the influence of local noise sources. Here, we introduce an approach to mitigate the influence of strong local sources in SSRn and SSRh. Our workflow relies on a clustering algorithm to select the Fourier Amplitude Spectrum (FAS) used in the SSRn and SSRh computation. By applying this method, we were able to remove strong anthropic transient signals at some sites and therefore improve the amplification assessment above 1Hz through the SSRn and SSRh. However, half part of the array is located nearby permanent anthropic sources that remain a major issue in quantifying the amplification at the scale of the valley. This study provides some insights into the conditions of applications of SSRn and SSRh in noisy industrialized environments.
Characterization and detection of avalanche signals using a seismo-acoustic array
Authors: Seupel Christine , Pérez Guillén Cristina , van Herwijnen Alec
Published: March 2022

Seismic and infrasound monitoring systems have been used for remote detection and characterization of avalanches and their dynamics. Recent studies have shown that seismic and infrasound methods are very complementary. Infrasound signals from avalanches are relatively easy to detect automatically but only contain partial information about the avalanche. Seismic signals, on the other hand, are more difficult to detect automatically but contain more information about the entire avalanche. To exploit the advantages of both wave types, we installed a combined seismo-acoustic array consisting of five seismometers and five infrasound sensors at our field site in Dischma valley above Davos. Additionally, we obtained ground-truth data on avalanches from several automatic cameras, field surveys and drone flights.

Results from data collected over two winter seasons show that both dry- and wet-snow avalanche were detected by our system, and highlight differences in seismic and infrasound wave characteristics depending on the avalanche type and size. Specifically, detection distance increased with avalanche size for both wave types. Furthermore, differences in seismic and infrasound signal characteristics were generally more pronounced for wet-snow avalanches than for dry-snow avalanches. Using array techniques we localized the avalanche paths and extracted seismic and infrasound waveform features. We also trained a machine learning model to automatically identify signals generated by avalanches, with promising results. Overall, our results indicate that combining seismic and infrasound wave characteristics can improve the remote detection and characterization of avalanches.
Ring Current Reconstruction via Multi-Satellite Observations and Comparison with VERB-4D Reanalysis Data
Authors: García Peñaranda Marina
Published: March 2022

The Earth’s ring current is a complex dynamic system that plays an important role in geomagnetic storms. This ring-shaped current environment changes its structure and intensity on different time scales as a result from the incoming solar wind. Particle populations display very different behaviors, making it extremely hard to develop physics-based forecasting models for the ring current environment.

 

Satellite data provides electron point measurements that can be used to study the different physical processes occurring in the Earth’s magnetospheric ring current. However, in order to fully understand the particle dynamics and injection processes in this region, high temporal and spatial data resolutions are required. We attempt to tackle this issue by using a combination of electron-flux observations from different satellite missions and instruments, in order to improve the global resolution of this dynamic environment.

 

In this work, we present a global reconstruction of the ring current population (energies from 1to a few 100 keV) using global multi-satellite data from Arase, POES, GOES, THEMIS and the Van Allen Probes (RBSP) missions. We achieved this by intercalibrating the satellite data for the year 2017.

Additionally, we present a comparison of the observed electron flux environment with a re-analysis of the ring current region obtained by using  the simplified version of the VERB-4D, which solves the convection equation and reduces the problem to a two-dimensional case by using parameterized lifetimes. For the reanalysis, we assimilate GOES and Van Allen Probes (RBSP A and RBSP B) data with a Stardard Kalman Filter.