bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrating Raman spectroscopy and LA-ICP-MS 2D imaging to decipher the localisation and chemistry of impurities on the micro-scale in Greenland ice: Consistencies and open question
Authors: Stoll Nicolas , Bohleber Pascal , Hörhold Maria , Erhardt Tobias , Eichler Jan , Roman Marco , Delmonte Barbara , Barbante Carlo , Weikusat Ilka
Published: March 2022

Impurities in polar ice play, among others, a crucial role as a proxy for the paleoclimate while at the same time impacting the internal deformation of ice on the micro-scale. In particular, solid and dissolved impurities can impact grain growth through Zener pinning or the drag of grain boundaries. Recent studies on natural ice from Antarctica and Greenland highlight the need for a multi-method approach to determine the differences in the localisation and chemistry of solid and dissolved impurities comprehensively, in order to ultimately gain a more holistic understanding. Here we report on a recent pilot investigation pursuing the direct integration of complimentary methods: microstructure-mapping, Cryo-Raman spectroscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) with 2D impurity imaging. While LA-ICP-MS enables the fast mapping of cm-size areas with lateral resolution in the order of tens of μm, Raman spectroscopy is more suited to identify the mineralogical composition of individual solid inclusions at the single μm scale. We analysed samples from the Holocene and Last Glacial from the Northeast Greenland Ice Core Project (EGRIP) and the North Greenland Eemian Ice Drilling (NEEM) ice cores. We find that the general localisation patterns of impurities (e.g., low vs. high concentration) are similar for both methods. Furthermore, both methods show (clusters of) inclusions in the grain interior. These findings display that a holistic approach is needed to truly decipher the localisation of impurities in the ice microstructure. Combining the advantages of both methods gives a good overview of the localisation of impurities, both solid and dissolved, on the micro-scale. Localisation patterns are related to the chemistry of the analysed impurities displaying the need for high-resolution methods. For example, Na is strongly located in the grain boundaries, Al is preferentially located within the ice grains and Mg can be located in both regimes. We analyse the role of inclusions in relation to 1) their chemistry and 2) their proximity to grain boundaries. Our approach of 2D impurity imaging in concert with established techniques, such as microstructure mapping and Raman spectroscopy, provides a detailed insight into the impurity distribution throughout a broad range of depths in an ice core. We demonstrate the potential of such an approach to carefully investigate the evolution of impurity localisation in ice cores, with special significance to ice deformation processes and the preservation of the climatic record.
How middle and upper continental crust reacts to prolonged extension: some clues from the Simplon Fault Zone (Central Alps)
Authors: Montemagni Chiara , Zanchetta Stefano
Published: March 2022

Crustal scale low-angle normal faults are typical tectonic features in orogenic post-collisional setting driving the exhumation of deep portions of the orogenic wedge. These extensional structures are commonly active at mid to upper crustal levels within quartz- and feldspar-rich rocks. As deformation localizes along these large-scale shear zones, the understanding of mechanisms controlling their development could provide invaluable insights on the rheology of the continental lithosphere. PT ambient conditions, differential stress, pore fluid pressure and time duration of activity are all factors that could significantly operate on how a shear zones develops in space and time.

We investigated by means of a quantitative approach the evolution of the Simplon Fault Zone (Western Alps, N Italy – Switzerland). We took into account: (i) meso- and microstructures distribution across the shear zone, (ii) its time of activity by 40Ar/39Ar dating of syn-shearing micas, (iii) vorticity distribution across the shear zone and its correlation with mylonite ages, (iv) the estimates of magnitude and variation of differential flow stress and strain rates during shear zone evolution obtained through EBSD-assisted quantitative microstructural analysis. All these data have been combined to reconstruct the structural evolution of the shear zone as the result of the rheological response of involved rocks to changing PT and stress conditions.

The Simplon Fault Zone formed as an extensional detachment accommodating E-W directed lateral extrusion after the collision between Adria and Europe. Several tens of kilometres of extension were accommodated by this structure, allowing the exhumation of the deepest portions of the Central Alps. The shear zone evolved from epidote-amphibolite to greenschist facies and then brittle conditions during shearing. A decrease of simple shear component from c. 90% to c. 40% towards the top of the shear zone is observed, with mylonites displaying ages within the 12-8 Ma time interval. Calculated  differential stress (60-80 MPa) and strain rate (10-11-10-12 s-1) estimates are in agreement with values displayed by several others crustal-scale low-angle normal faults developed at medium to shallow crustal levels.

The quantitative approach used at different scales pointed out that the Simplon Fault Zone experienced a complex evolution, with shear strain that was heterogeneously distributed across the fault zone. Despite this heterogeneity, a general decrease of the simple shear component and increase of the differential flow stress toward the top of the shear zone is clearly defined.
Depressed 660-km seismic discontinuity beneath cold subduction zones caused by akimotoite-bridgmanite phase transition
Authors: Chanyshev Artem , Ishii Takayuki , Bondar Dmitry , Bhat Shrikant , Kim Eun Jeong , Farla Robert , Nishida Keisuke , Liu Zhaodong , Wang Lin , Nakajima Ayano , Yan Bingmin , Tang Hu , Chen Zhen , Higo Yuji , Tange Yoshinori , Katsura Tomoo
Published: March 2022

The 660-km seismic discontinuity (D660) is the boundary between the Earth’s lower mantle and transition zone and is commonly interpreted as the dissociation of (Mg,Fe)2SiO4 ringwoodite to (Mg,Fe)SiO3 bridgmanite plus (Mg,Fe)O ferropericlase (post-spinel transition). Prominent features of D660 are significant depressions to 750 km and multiplicity beneath cold subduction zones. Previous high-pressure experiments provided negative but gentle Clapeyron slopes (−1.3 to −0.5 MPa/K) of the post-spinel transition. Thus, the post-spinel transition cannot interpret the D660 depression. Therefore, another phase transition with a steep negative slope is required, and the akimotoite−bridgmanite transition in (Mg,Fe)SiO3 is one candidate.

In the current study, we determined the boundaries of the post-spinel (RBP) and akimotoite−bridgmanite (AB) phase transitions in the MgO-SiO2 system over a temperature range of 1250–2085 K using advanced multi-anvil techniques with in situ X-ray diffraction. We judged a stable phase assemblage by observing relative increase/decrease in the ratio of coexisting high- and low-pressure assemblages at spontaneously and gradually decreasing pressure and a constant temperature from diffraction intensities. Since this strategy is strictly based on the principle of phase equilibrium, it excludes problems in determining phase stability caused by sluggish kinetics and surface energy.

We found that the RBP boundary has a slightly concave curve, whereas the AB boundary has a steep convex curve. The RBP boundary is located at pressures of 23.2–23.7 GPa in the temperature range of 1250–2040 K. Its slope varies from −0.1 MPa/K at temperatures less than 1700 K to −0.9 MPa/K at 2000 K with an averaged value of −0.5 MPa/K. The slope of the AB boundary gradually changes from −8.1 MPa/K at low temperatures up to 1300 K to −3.2 MPa/K above 1600 K. Based on these findings, we predict that, beneath cold subduction zones, ringwoodite should first dissociate into akimotoite plus periclase, and then akimotoite transforms to bridgmanite with increasing depth; these successive transitions cause the multiple D660. Moreover, the steep negative boundary of the AB transition should result in cold-slab stagnation due to significant upward buoyancy. Our predictions are supported by the seismological observations beneath cold (e.g., Tonga, Izu-Bonin) subduction zones.
Assessing regional climate simulations over the southwestern South Atlantic Ocean: added value of wind speed in coastal and oceanic regions
Authors: Silva Natalia Pillar da , Crespo Natália Machado , Camargo Ricardo de , da Rocha Rosmeri Porfírio
Published: March 2022

Coastal activities are impacted by wind speed and wave height regimes, and extreme events can cause severe damage to structures along the coastline. Over the southwestern South Atlantic Ocean, several oil and gas offshore facilities are exposed to such events, therefore the study of wind speed climate is of great importance. Given the coarse horizontal resolution of Global Climate Models (GCMs), local studies benefit from the nesting Regional Climate Models (RCMs) in global domains for a better representation of regional processes. Several regional climate studies focus on the evaluation of RCMs for mean climate conditions of temperature, precipitation and pressure. The present study aims to evaluate wind speed results from two different RCMs: Regional Climate Model system version 4 (RegCM4) and the Weather Research and Forecasting (WRF). Two types of experiments were conducted: (1) hindcasts with reanalysis data from ERA-Interim and CFSR; (2) historical climate simulations using HadGEM2-ES and MPI-ESM-MR. Output from all simulations were evaluated with a satellite-based dataset from the Cross-Calibrated Multi-Platform wind product (CCMP), given the lack of observational data over coastal and oceanic regions. Preliminary results point to an overestimation (underestimation) of wind speed in all RegCM4 (WRF) simulations, with a more pronounced difference for upper quantile values.
The Index of Connectivity on trial. How reliable is IC to quantitatively assess sediment connectivity in mountain basins? 
Authors: Martini Lorenzo , Cavalli Marco , Picco Lorenzo
Published: March 2022

In mountain catchments connectivity regulates the capability of sediment to be transferred from sediment source areas to the stream network. Raster-based indices, such as the Index of Connectivity (IC), have become a widely used tool for analysing the relationships facilitating or inhibiting the coupling among different compartments of the catchment. However, despite the numerous applications in literature, few studies have tested the capability of IC to quantitatively represent the linkages between sediment sources and channels and to predict potential new linkages. In this study, the aim is the semi-quantitative validation of IC as a tool for depicting structural connectivity and for predicting sediment dynamics in a mountain basin. Moreover, a specific objective is to derive a crisp threshold between high and low connectivity that could enhance the communication of IC maps. To this end, a benchmark was set regarding the actual connectivity status of 420 sediment source areas present in a mountain headwater catchment in the Dolomites (Italy). The assessment of connectivity status was carried out through remote sensing analysis and field observations. Then, multiple IC variants were computed changing the weighting factor and the pixel resolution of the input DTM. Finally, logistic regression analyses were performed using the different IC variants as independent variables and connectivity status as dependent variable. Therefore, the predictive capacity of IC was tested and a crisp IC threshold was obtained to discriminate connected and disconnected sources. The results showed that only 64 out of 420 sediment sources are connected to the channel network. Moreover, IC as a structural index proved to be suited to depict structural connectivity whereas fails to fully represent process-induced sediment linkages, i.e. functional connectivity. Finally, it was possible to derive an IC threshold of -2.32, useful to differentiate between high and low IC and useful to improve IC maps. The threshold functions as a clear boundary between disconnected and connected sources but only applicable to the catchment under investigation. Nevertheless, the overall approach can be transferred to other mountain areas.
Numerical analysis of the middle Adriatic upwelling 
Authors: Beg Paklar Gordana , Medugorac Iva , Mihanovic Hrvoje , Orlic Mirko , Pasaric Zoran , Stanesic Antonio
Published: March 2022

Extensive, but short oceanographic measurements were conducted in the spring seasons from 2017 to 2021 with an aim to investigate the middle Adriatic upwelling. The exception was cruise in 2020, when measurements were performed in August. As cruises have been conducted under different meteorological and hydrological conditions, high resolution CTD and shipborne ADCP measurements revealed strong variability in the upwelling strength and occurrence. The strongest upwelling, both in the coastal and open sea area, was recorded in May 2017 and it was related to strong NNW winds that had been blowing for several days before and during the 2017 cruise. Field measurements in June 2018, although conducted under upwelling-favourable winds from NW direction, revealed a rather flat pycnocline due to the low wind intensity, except in the first 5 km close to the coast where the pycnocline was rising onshore. Coastal upwelling was also recorded during the following cruises in June 2019, August 2020 and May 2021, whereas rising of thermocline through Ekman pumping in the open sea was detected only in May 2021. To overcome limitations of the measurements and to shed more light on the upwelling dynamics and its occurrence, realistic and idealised ROMS model simulations are conducted. Realistic simulations are performed by Adriatic scale ROMS model forced by surface momentum, heat and water fluxes calculated using results of operational numerical weather prediction model ALADIN-HR. In addition to atmospheric forcings, river discharges, tides and water mass exchange through the Strait of Otranto are also implemented in the realistic simulations. Reliable results of the realistic baseline experiments, assessed with available in situ and satellite data, allowed us to define sensitivity studies. Sensitivity experiments focus on the influence of both local and remote processes, particularly on the Adriatic river discharges and their parameterization in the ROMS simulations, as well as on the external dynamics and its parameterization at the model open boundary. Strength and character of the middle Adriatic upwelling simulated in the experiments with two available Adriatic river climatologies show no significant distinctions. Moreover, sensitivity of the model results to horizontal grid spacing of atmospheric forcing and oceanographic model grid is investigated. To further elucidate upwelling mechanism, additional idealised simulations with homogeneous upwelling-favourable wind for the eastern Adriatic coast from NW direction are set up and run.
Extreme IOD induced IOB warming and its impacts on western North Pacific anomalous anticyclonic circulation transport in early summer 2020: without significant El Nino influence
Authors: Du Yan , Cai Yinan , Chen Zesheng , Zhang Ying
Published: March 2022

The tropical Indian Ocean (TIO) basin-wide warming occurred in 2020, following an extreme positive Indian Ocean Dipole (IOD) event instead of an El Niño event, which is the first record since the 1960s. The extreme 2019 IOD induced the oceanic downwelling Rossby waves and thermocline warming in the southwest TIO, leading to sea surface warming via thermocline-SST feedback during late 2019 to early 2020. The southwest TIO warming triggered equatorially antisymmetric SST, precipitation, and surface wind patterns from spring to early summer. Subsequently, the cross-equatorial “C-shaped” wind anomaly, with northeasterly–northwesterly wind anomaly north–south of the equator, led to basin-wide warming through wind-evaporation-SST feedback in summer.

The TIO warming excited a strong and westward extend anomalous anticyclone on the western North Pacific (WNPAC). The WNPAC is usually associated with strong El Niño-Southern Oscillation (ENSO), except for the 2020 case. In 2020, the anomalous winds in the northwestern flank of the WNPAC bring excess water vapor into central China. The water vapor, mainly carried from the western tropical Pacific, converges in central China and result in heavy rainfall. Unlike extreme events in 1983, 1998, and 2016, the extreme rainfall in 2020 was the first and only event during 1979-2020 that followed an extreme positive IOD rather than a strong El Niño. A theory of regional ocean-atmosphere interaction can well explain the processes, called the Indo-Western Pacific Ocean Capacitor (IPOC) effect. This study reveals the importance of IOD in the IPOC effect, which can dramatically influence the East Asian climate even without involving the ENSO in the Pacific.
Combination of GNSS, VLBI and SLR data for consistent estimation of Earth Rotation Parameters
Authors: Lengert Lisa , Flohrer Claudia , Girdiuk Anastasiia , Hellmers Hendrik , Thaller Daniela
Published: March 2022

We present the current activities of the Federal Agency for Cartography and Geodesy (BKG) towards a combined processing of VLBI, GNSS and SLR data. The main goal of the combined analyses of the three different space-geodetic techniques is the improvement of the consistency between the techniques through common parameters, i.e., mainly Earth Rotation Parameters (ERPs). The combination is based on homogenized, datum-free NEQs which allow a rigorous combination on the normal equation level instead of the observation level.

Based on our previous combination studies using GNSS data and VLBI Intensive sessions on a daily and multi-day level, we generate a consistent, low-latency ERP time series with a regular daily resolution for polar motion and dUT1. We achieved in this way a significant accuracy improvement of the dUT1 time series and a slight improvement of the pole coordinates time series, comparing ERPs from the combined processing with the individual technique-specific ERPs.

In the second step, we extend the multi-day combination of GNSS and VLBI Intensive sessions by adding VLBI 24-hour sessions. The additional combination with VLBI R1/R4 data further stabilizes all ERPs twice per week and enables the estimation of high-precision ERP time series with a latency of about two weeks. With this combination approach, we obtained a further improvement in the dUT1 time series. For the pole coordinates time series, the accuracy of the estimates is almost at the same level as for the rapid combined solution.

In our recent studies, we want to investigate improvements in the representation of the ERP parameters of the VLBI 24-hour sessions. Furthermore, we want to extend the combination of GNSS and VLBI data by adding SLR sessions in order to exploit the benefit of the combination to its maximum extend. We expect that SLR improves the combined ERP solution in particular through a stable contribution of LOD. We analyse the impact of the combination on the global parameters of interest, i.e., mainly dUT1, polar motion and LOD, but also on station coordinates.

Based on the improved combination method, we intent to set up a new operational BKG-ERP product.
Monitoring annual snail activity cycles: field-testing paleoenvironmental assumptions
Authors: Kwiecien Ola , Breitenbach Sebastian , Kozielska Magdalena
Published: March 2022

Like many of our fellow geoscientists, the early 2020 outbreak of the COVID pandemic caught us moving countries and universities. With field work cancelled and access to laboratories restricted, many research projects came to a pause. Working from home in a new, and not yet explored scientific and (sub)urban landscape presented serious challenges but also previously overlooked opportunities.

Here we report the results of a nearly two-year long monitoring of local temperature and isotopic composition of precipitation coupled with observations on the activity of the brown garden snail (Cornu aspersum) in Great Park, Newcastle upon Tyne, northeastern UK. Land snail shells are often used as archives of past environmental conditions (temperature and/or precipitation), but untested assumptions on when they form their shells might bias the interpretation. Snails precipitate their carbonate shell only during the active growth phases, while they remain dormant when conditions are too cold (hibernation) or too dry (aestivation). Thus, depending on the regional/ local conditions snail shells constitute a seasonally biased environmental archive, but this fact is often either oversimplified or completely overlooked.

The Köppen-Geiger climate classification defines UK climate as oceanic (Cfb temperate climate without dry season, but warm summers). Northeast England experiences maximum temperatures in summer (JJA) and lowest in winter (DJF), whereas precipitation is relatively homogenously distributed throughout the year, with highest rainfall in autumn and winter (SONDJF). Our local observations confirm that C. aspersum is most active during the night and directly after rainfall. As expected, the Great Park snail population does not aestivate during summer but hibernates in winter, starting when temperatures drop below ca. 7°C in late November. Contrary to expectations, the emergence from hibernation does not seem to be temperature- but precipitation-driven, and commences after the first heavy rainfall in May, independent of air temperature. Our ongoing monitoring work calls for careful assessment when interpreting the isotopic composition of fossil shells in terms of mean annual conditions.
Initial soil formation in an artificial river valley - Interplay of anthropogenic landscape shaping and fluvial dynamics
Authors: Schulte Philipp , Hamacher Hendrik , Lehmkuhl Frank , Esser Verena
Published: March 2022

 Recultivation is a strategy for restoring near-natural landscape systems in anthropogenically influenced environments. Especially in post-mining landscapes after open pit mining, recultivation gives opportunities and potential for near-natural landscape modeling. In order to evaluate the success of the applied measures, biological monitoring approaches with a focus on biodiversity are often carried out. However, the loss of natural soils, which are the result of long-term formation, is an irreversible damage to the pedosphere. The natural soil functions must be completely re-established and it is difficult to examine its success. In our study we therefore investigated initial soil formation in an morphodynamically active artificial river valley, modeled and constructed with a recultivation substrate called “Forstkies”. The study area is located in the catchment of the Inde River (North Rhine-Westphalia, Western Germany), which is part of the international River Basin District Meuse. Due to the progress of the open pit lignite mining, a 5 km long river course had to be relocated. With the aim of creating a near-natural landscape and an appropriate development corridor for the river, a ~ 12 km long river relocation was designed. The artificial river section "Neue Inde" is still geomorphologically naïve and characterized by temporary, highly energetic morphodynamic processes resulting in strong erosion processes in the river bed and the surrounding area. To characterize the morphodynamics and to detect initial soil formation processes, we analyzed a transect of seven soil profiles. The transect includes floodplains and slope areas further away from the river. Allochthonous flood sediments can be differentiated from the underlying artificial Forstkies sediments by inherited contamination of the heavy metals Pb, Zn and Cu. By means of common soil parameters (grain size, CaCO3, total organic carbon, pH value and sediment colors) and geochemical weathering indices, first initial post-sedimentary alterations can be detected. The quality of the soils is absolutely appropriate to the state of development. The results obtained can be helpful for the planning of future renaturation in post-mining landscapes.  
Plate tectonic degassing estimated from full-plate models and age distributions of arc-related zircons
Authors: Torsvik Trond H. , Marcilly Chloe M. , Domeier Mathew , Royer Dana L.
Published: March 2022

Plate tectonics regulates atmospheric greenhouse gas concentrations and surface temperatures via sources (mainly volcanic CO2 degassing) and sinks (silicate weathering and carbonate deposition). To constrain arc-volcanism, the main source of CO2, we argue that normalized subduction flux calculated from full-plate models is a reliable proxy, and notable peaks are observed during greenhouse conditions (e.g. the Early Cretaceous), whereas icehouse conditions are commonly characterized by reduced subduction flux (e.g. the Late Paleozoic Ice Age). The age distributions of arc-related zircons grossly mimic subduction fluxes and we present a new approach to estimate degassing through time by rescaling the global zircon age distribution to the subduction flux. Importantly, this approach permits estimation of plate tectonic degassing in deep time when full-plate models become increasingly unreliable. Full-plate models differ vividly before the assembly of Pangea, mainly due to different longitude-calibrations of continents and synthetic (“made-up”) oceanic realms, and variations in zircon-age-frequency allow us to estimate changes in volcanic arc-activity or plate tectonic degassing much more objectively in deep time. A first attempt to quantify volcanic arc-activity in deep time shows a pattern where low (high) degassing generally corresponds to periods of icehouse (greenhouse) for the past 3.5 billion years. We recognize a major shift in volcanic arc activity during the late Neoproterozoic (700-540 Ma) and this may reflect a transition to a modern-type plate tectonic regime with cold, deep and steep subduction.
Problems and Solutions: brGDGTs distributions and calibrations for semi-arid environments and application to the wetlands of the Southern Caucasus.
Authors: Cromartie Amy , Robles Mary , Joannin Sébastien , Dugerdil Lucas , Peyron Odile , Ménot Guillemette
Published: March 2022

The arid and semi-arid mountainous environment of the Southern Caucasus lies between the Black and Caspian Sea with elevations from below sea level to over 5000 m asl and has annual temperatures from -6˚ to 16˚C and precipitation between 200 - 2200 mm a year. Due to the large elevation changes in this mountainous zone, temperature and precipitation shifts occur quickly over short distances. The semi-arid regions here host a number of wetland contexts available for paleo-environmental research. However, recent investigations of branched glycerol dialkyl glycerol tetraethers (brGDGTs) records from a large wetland from the region note the changes in wetland development, from lake to peatland, impact the distribution of brGDGTs and the temperature reconstructions (Robles et al. 2022). To overcome these challenges Robles et al. (2022) applied a combination of global lake and soil calibrations to each section. New research on smaller wetlands, however, have found that these wetland transformations are not always as well defined and include periods of erosional soil inputs, open lake contexts, and eventual transformation to a wetland. In addition, soils from the region record a similar trend found in Gao et al., (2021) who found a temperature relationship with the MBT'6me suggesting the MBT'5me reconstructions do not fully capture the temperature profile. To address these issues we propose two avenues to reconstruct temperature and present our results. First, we evaluate the feasibility of utilizing a stepwise selection model for local configuration based on mixed samples (lake, wetland, soils) to overcome problems with changes in sediment overtime while capturing the temperature relationships between both the 5-methyl and 6-methyl brGDGT groups. Second, we utilize a probability based machine learning approach to estimate changes in source sediment distribution as the wetland transitions through time. We test both of these applications on downcore wetland sediments to evaluate our results. These results are compared with pollen reconstructions, aquatic pollen, non-pollen polymorphs, and XRF data in order to evaluate their success. We find that both methods can help provide better information for reconstructions.

 

Robles, Mary, et al. "Impact of climate changes on vegetation and human societies during the Holocene in the South Caucasus (Vanevan, Armenia): A multiproxy approach including pollen, NPPs and brGDGTs." Quaternary Science Reviews 277 (2022): 107297. 

Guo, Jingjing, et al. "Soil pH and aridity influence distributions of branched tetraether lipids in grassland soils along an aridity transect." Organic Geochemistry (2021): 104347. APA  

 
Characterization of Oligocene Oil Reservoir Sandstones for High Temperature Aquifer Thermal Energy Storage (HT-ATES) in the Upper Rhine Graben (URG), SW Germany
Authors: Steiner Ulrich , Ang Nyukshan , Bauer Florian , Schill Eva
Published: March 2022

The storage of low-temperature heat in the near surface underground is already widely used worldwide, whereas only little attempts of storing of higher temperatures have been made so far. However, this can become increasingly important in the heat transition strategy by contributing with this technology to medium and peak load supply. Previous works have demonstrated that a large part of the required thermal energy can be efficiently stored in former oil reservoirs in Tertiary sediments of the URG. The advantage of using depleted oil reservoirs as HT-ATES is that they have a lower overall project risk due to the knowledge of the subsurface from the exploration history and that the geological and geophysical data, which are mostly available, allow a more reliable forecast of efficiency and development costs.

KIT in Karlsruhe has now planned the "Deepstor" HT-ATES research infrastructure for its Northern Campus. The site is adjacent to the former Leopoldshafen oil field and can draw on a large amount of data from boreholes for assessment prior to drilling. The targeted reservoirs is the several meters in thickness consisting of fine-grained calcareous sandstones from the Oligocene Froidfontaine Formation at a depth of approx. 1,300 meters.

The baseline of this study is the interpretation of petrophysical data such as resistivity-, sonic-, gamma and SP-logs to derive hydrogeological and geothermal parameters in 15 deep wells in vicinity of the planned drilling site. An integrated data analysis is performed with simulations to gain a quantitative understanding of the fluid and heat flow of the HT-ATES site and to predict the storage and recuperation capacity. Poro-perm values from core material are used to calibrate the results. The aim is a statistically based assessment of the storage site for planning and cost estimation of the research infrastructure.

This work should provide further insights for the future development of geothermal heat storage and enable the integration of a HT-ATES in the KIT campus.
The complex plumbing system of Oldoinyo Lengai seen by 3D attenuation tomography
Authors: Reiss Miriam Christina , de Siena Luca , Muirhead James
Published: March 2022

Oldoinyo Lengai volcano, located in the Natron Basin (Tanzania), is the only active natrocarbonatite volcano worldwide. It thus represents an essential end-member magmatic system in a young rift segment (~3 Ma) of the East African Rift System. Following a period of relative quiescence after the 2007-08 explosive eruption and dike intrusions beneath the volcano itself and neighbouring inactive shield volcano Gelai, seismicity and effusive lava flows within the crater show a heightened level of activity since 2019. Employing data from a recent seismic experiment, Reiss et al. 2021 used seismicity and focal mechanisms patterns to map the complex volcanic plumbing system and its impact on rift processes.

Here, we use the recorded waveforms of local earthquakes to employ the newly developed 3D multi-scale reasonable attenuation tomography (MuRAT) to constrain the complex volcanic plumbing system in unprecedented detail. Our attenuation analysis measures peak delay and coda wave attenuation to separately measure seismic scattering, attenuation and absorption and model those parameters in 3D. Compared to a classical travel time tomography, this allows us to map seismic interfaces such as faults, fluid reservoirs and melt batches. We use over 20 000 waveforms and perform a separate inversion for coda wave attenuation and a regionalisation for peak delay measurements in different frequencies, which are sensitive to different structures and depths.

While the lower frequencies are sensitive to larger-scale features and structures close to the surface, the higher frequencies provide better resolution on smaller features and structures at depth. Accordingly, we map different aspects of the complex 3D plumbing system of Oldoinyo Lengai and the rift itself in different frequencies. Our results show strong scattering and attenuation near fluid-filled, deep-reaching faults, producing seismic swarms. We also detect the existence of previously unknown, small magma reservoirs in the shallowest part of the crust that might have fed previous dike intrusions and clearly shows an interconnected plumbing system stretching from the border fault across a developing magmatic rift segment.
Detecting the spatio-temporal propagation of heat waves in a regional single-model large ensemble
Authors: Böhnisch Andrea , Felsche Elizaveta , Ludwig Ralf
Published: March 2022

Heat waves are among the most hazardous climate extremes in Europe, commonly affecting large regions for a considerable amount of time. Especially in the recent past heat waves account for substantial economic, social and ecologic impacts and loss. Projections suggest that their number, duration and intensity increase under changing climate conditions, stressing the importance of quantifying their characteristics. Yet, apart from the analysis of single historical events, little research is dedicated to the general propagation of heat waves in space and time. 

Heat waves are rare in their occurrence and limited observational data provide little means for robust analyses and the understanding of dynamical spatio-temporal patterns. Therefore, we seek to increase the number of analyzable events by using a single-model initial condition large ensemble of a regional climate model (Canadian Regional Climate Model Version 5, CRCM5-LE). This provides 50 model members of comparable climate statistics to robustly assess various spatial patterns and pathways of European heat waves in a data set of high spatial resolution. 

Using the CRCM5-LE allows us to explore a novel data-driven approach to infer cause-and-effect relationships, in this case the spatio-temporal propagation of spatially distributed phenomena. Our aim is to investigate specifically the transitions and inter-dependencies among heat wave core regions in Europe to better understand their evolution during the recent past.

We define heat waves as a minimum of three consecutive hot days with temperatures above the 95th JJA (1981-2010) percentile. If a reasonable fraction of the domain land area exhibits a hot day, this time step is used for clustering in order to derive core regions. Each core region is represented by a spatially aggregated time series of the cluster footprint. The approach further includes the derivation of directed links between these core regions using causal discovery and the analysis of associated atmospheric conditions.

Results indicate that directed links among core regions of heat wave occurrence over Europe reproduce parts of observed movements. This helps to group and characterize heat waves according to, e.g. seasonality. Examples of these heat wave cluster transitions show an associated shift of high pressure patterns, suggesting that the approach allows capturing the spatial dislocation of heat wave centers. 
Influence of water resource management on runoff trapping under different rainfall events based on remote sense technology in steep-slope agricultural landscapes
Authors: Wang Wendi , Straffelini Eugenio , Tarolli Paolo
Published: March 2022

One of the important issues faced by human in 21st century is to meet the need of food particularly in the background of increasing population. Steep-slope agricultural landscapes are making a relevant contribution for food protection. To protect and mitigate the impact of more frequent rainfall events as well as improve the food production in, more researches about how to increase water resource efficiency and management is necessary. In addition, understanding the interactions between water management infrastructure and runoff process is a great concern on the sustainable development of steep-slope agricultural landscapes. Several researches focused on water and soil conservation measures aims at soil erosion control, while less studies were conducted to study on runoff trapping under different rainfall intensities and water managements measures through the remote sensing data. In this study, we simulated surface water flow under different rainfall events before and after the application of designed water storages network to search the best solution for water runoff mitigation and water conservation in steep-slope agricultural areas. In detail, our works focus on (1) to design the sustainable and cost-effective water management infrastructures to the study area; (2) to quantify the amount of water resource maintained by appropriate management measures; (3) to simulated the overflow in steep slope agricultural areas under different rainfall conditions using hydrologic model based on high-resolution topography derived by remote sense data, with the aims to test the impacts of designed water storages in saving water and mitigating runoff. The research results not only have theoretical significance, but also provide a more accurate example of the how to design the reliable water resource managements in steep slope agricultural areas under the background of climate change.
Catchment dissolved organic carbon transport: a modeling approach combining water travel times and reactivity continuum
Authors: Grandi Giulia , Bertuzzo Enrico
Published: March 2022

Quantifying the transfer of organic carbon from the terrestrial to the riverine ecosystems is  of crucial importance to fully appreciate the carbon cycle at the catchment, regional and global scales. Specifically, the entity of dissolved organic carbon (DOC) fluctuations in streamflow is of particular interest also for their impact on the nutrient cycles and on water quality, with implications also for drinking water treatment. In this study, we propose a framework for modelling the flux of DOC from hillslopes to stream and river networks which couples a transport model based on water travel time distributions with the reactivity continuum theory to model DOC degradation. We test the model by applying it to the Plynlimon catchments (UK) exploiting both weekly and high-frequency (7-hour interval) time-series. Besides DOC concentration data, we use information about chloride to get an independent estimate of water travel times using the framework of StorAge Selection functions. The composition and the degradation of DOC along the flowpaths is described assuming a continuous spectrum of quality which initially follows a gamma distribution. Results show that, chiefly for high-frequency measurements, the model is able to reproduce reasonably well both chloride and DOC streamflow concentrations and to capture the complex hysteretic relation between DOC concentration and discharge. The distribution of the age of the water comprised in the streamflow proves thus a key variable to predict the quantity but also the quality of the DOC exported from soils, and the effect of hydrologic variability on this process. Starting from the proposed framework and the results obtained, we discuss how future developments could help in shedding light on the complex relations among carbon, water cycle and the metabolic balance of riverine ecosystems.
Boron-rich hydrothermalism marking Early Permian extensional structures of the central Southern Alps, N Italy
Authors: Locchi Sofia , Trumbull Robert B. , Zanchetta Stefano , Moroni Marilena , Zanchi Andrea
Published: March 2022

During the Early Permian, the post-Variscan evolution of the present-day Alpine region was characterized by crustal extension combined with strong magmatic activity at different crustal levels (Schaltegger and Brack, 2007), which finally led to the development of intracontinental extensional basins filled with volcanoclastic sediments (e. g. the Orobic Basin). In the central Southern Alps (cSA) N Italy, the opening of these basins was controlled by low-angle normal faults (LANFs). We investigated several Early Permian faults of the Orobic Basin with emphasis on their original features, as they have exceptionally escaped most of the Alpine deformation (Blom and Passchier, 1997). The identified LANFs of the Orobic Basin are characterized by cataclastic bands sealed with cm to dm thick layers of dark, aphanitic tourmalinites (Zanchi et al., 2019). The tourmalinites formed in response to circulation of boron-rich fluids channelled along Early Permian fault systems related to opening of the Orobic Basin. The tourmalinized faults were first noted in various sites of the cSA during the 1990’s: several authors linked them to the uranium mineralization of the Novazza-Val Vedello district (Slack et al., 1996; Cadel et al., 1996; De Capitani et al., 1999), although their genesis has never been fully characterized and the connection with U-ore bodies has also not been deeply investigated so far.

In this work, we further characterize the occurrence and assess the cause of the regional hydrothermalism in the context of intracontinental extension during the Early Permian. Field-based structural analysis are combined with mineral and whole-rock geochemistry, geochronology, microstructural studies and boron- isotopic analysis of tourmalinites from different sectors of the study area, in order to evaluate the origin of hydrothermal fluids. Preliminary results demonstrate a temporal relationship between tourmalinites and Early Permian magmatism in the cSA. Geochemical data on major and trace elements together with B isotope ratios suggest a direct connection between tourmalinites and the U-mineralization at the basement-cover contact and along LANFs within the Orobic Basin.

 

Blom, J. C., and Passchier, C. W. (1997). Geologische Rundschau, 86, 627-636.

Cadel, G., et al. (1996). Memorie di Scienze Geologiche, 48, 1-53.

De Capitani, L., et al. (1999). Periodico di Mineralogia, 68, 185-212.

Schaltegger, U., and Brack, P. (2007). International Journal of Earth Sciences, 96(6), 1131-1151.

Slack, J., F., et al. (1996). Schweiz. Mineral. Petrogr. Mitt., 76, 193-207.

Zanchi A. et al. (2019). Italian Journal of Geosciences, 138, 184-201

 
Long-term harmonized ozone profiles in the middle atmosphere over Switzerland 
Authors: Sauvageat Eric , Maillard Barras Eliane , Hocke Klemens , Haefele Alexander , Murk Axel
Published: March 2022

Two decades ago, concentration of ozone-depleting substances in the middle atmosphere started a slow decline as a result of the Montreal Protocol. Since then, stratospheric ozone recovery is expected and has already been observed over some parts of the world, e.g. the Antarctic. Over the mid-latitudes however, the situation is less obvious, and ozone recovery seems to differ depending on the altitude and the geographical area of interest. In view of these uncertainties, there is still a strong need for high-quality and long-term ozone observations and their validation.

Switzerland has a number of stations monitoring ozone using different techniques. In particular, it is the only place in the world with two collocated ground-based ozone microwave radiometers. Located less than 50 km apart, they provide continuous hourly ozone profiles in the middle-atmosphere (~20 to 75 km) since more than 20 years with very few interruptions. Both instrument are part of the Network for the Detection of Atmospheric Composition Change (NDACC) and are regularly used for ozone trend studies or cross validation of satellite observations over Central Europe.

Despite the many studies conducted with these instruments, some anomalous periods and discrepancies in trends were recently identified in their time series. To address these problems, a full harmonization and reprocessing of the data was performed with the aim of obtaining two improved and independent time series. This harmonization affects the calibration of the radiometric measurements, flagging procedures and the retrievals of atmospheric profiles and has now been completed for the last decade.

In this contribution, we present and compare the new harmonized ozone time series for both instruments and highlight the improvements in the ozone retrievals compared to the old data processing. We also perform a comparison of these new data series against measurements from the Microwave Limb Sounder and the Solar Backscatter Ultraviolet Radiometer over Switzerland. As an additional validation, we show some first results of diurnal cycles derived from the new harmonized data series and compare it with model-based diurnal ozone climatology.
Estimating large scale dynamic mountain glacier states with numerical modelling and data assimilation
Authors: Schmitt Patrick , Maussion Fabien , Gregor Philipp
Published: March 2022

Ongoing global glacier retreat leads to sea-level rise and changes in regional freshwater availability. For an adequate adaptation to these changes, knowledge about the ice volume and the current dynamic state of glaciers is crucial. At regional to global scales, sparse observations made the dynamic state of glaciers very difficult to assess. Thanks to recent advances in global geodetic mass-balance and velocity assessments, new ways to initialize numerical models and ice thickness estimation emerge. In this contribution, we present the COst Minimization Bed INvErsion model (COMBINE), which aims to be a cheap, flexible global data assimilation and inversion method. COMBINE uses an existing numerical model of glacier evolution (the Open Global Glacier Model, OGGM) rewritten in the machine learning framework PyTorch. This makes the model fully differentiable and allows to iteratively minimize a cost function penalizing mismatch to observations. Thanks to the flexible nature of automatic differentiation, various observational sources distributed in time can be considered (e.g. surface elevation and area changes, ice velocities). No assumption about the dynamic glacier state is needed, releasing the equilibrium assumption often required for large scale ice volume computations. In this contribution, we will demonstrate the capabilities of COMBINE in several idealized and real-world applications, and discuss its added value and upcoming challenges for operational application.