bluuebunny/crossref_metadata_2025 huggingface dataset:
Individual and Interactive Effects of Elevated CO2, Warming and Drought on the Phenology of Mountain Grassland
Authors: Joseph Lumnesh Swaroop Kumar , Cremonese Edoardo , Migliavacca Mirco , Schaumberger Andreas , Bahn Michael
Published: March 2022

Mountain grasslands are strongly exposed to multiple global changes, including elevated CO2, climate warming and the increased occurrence of drought events. While the individual effects of these global change drivers on the phenology of grasslands have been comparatively well studied, there is a lack of understanding of their interactive effects. In a multifactor global change experiment on a managed montane grassland typical for many parts of the Alps, we tested the individual and combined effects of elevated CO2 (eCO2; +300 ppm), warming (eT; +3°C) and severe summer drought on phenology. We derived the canopy-level phenological transition dates from Green Chromatic Coordinates (GCC) time series calculated from phenocam images. Preliminary results reveal that warming, individually and when combined with elevated CO2, led to an early spring advancement and that drought accelerated senescence, more strongly under future (eCO2 + eT) compared to ambient conditions. Our preliminary findings suggest non-additive effects of interacting global change drivers on the phenology of mountain grassland, with cascading consequences for grassland productivity.
High-frequency, multi-elemental stream concentration timeseries as a tool for catchment flowpath identification
Authors: Brekenfeld Nicolai , Fovet Ophélie , Blanchouin Arnaud , Cordier Laure , Cotel Solenn , Faucheux Mikaël , Floury Paul , Fourtet Colin , Hamon Yannick , Henine Hocine , Petitjean Patrice , Pierson-Wickman Anne-Catherine , Pierret Marie-Claire , Gaillardet Jérôme
Published: March 2022

Stream water chemistry at catchment outlets is commonly used to infer the flowpaths of water through the catchment and to quantify the relative contributions of various flowpaths. High-frequency and multi-elemental timeseries could shed light on the dynamic activation/deactivation and the changing relative contributions of different flowpaths during storm events or diel cycles in summer. Here, we present multi-year, high-frequency (< 60 minutes) timeseries of the major cations and anions from the outlet of three small (0.8 – 40 km²) french catchments with contrasting land-use (forest, field crops and mixed farming-cropping productions). Instead of analysing the concentration dynamics of individual elements, we use elemental ratios in order to identify the contrasting temporal variations of different elements during storm events. We try to link the dynamics of the elemental ratios to specific flowpaths, constrained by the processes likely to modify the ratios. Then, we compare the inferred flowpath contributions with our perceptual understandings of the three catchments. These findings contribute to our understanding of dynamic flowpath activation in catchments and the value of high-frequency, multi-elemental stream concentration timeseries.
Temporal evolution of dissolved gases in groundwater of Tenerife Island
Authors: Amonte Cecilia , Pérez Nemesio M. , Melián Gladys V. , Asensio-Ramos María , Padrón Eleazar , Hernández Pedro A. , Meire Feijoo Ana
Published: March 2022

The oceanic active volcanic island of Tenerife (2,034 km2) is the largest of the Canarian archipelago. There are more than 1,000 galleries (horizontal drillings) in the island, which are used for groundwater exploitation and allow reaching the aquifer at different depths and elevations. This work presents the first extensive study on the temporal variation of dissolved gases in groundwaters from Fuente del Valle and San Fernando galleries (Tenerife, Spain) since April 2016 to June 2020. This investigation is focused on the chemical and isotopic content of several dissolved gas species (CO2, He, O2, N2 and CH4) present in the groundwaters and its relationship with the seismic activity registered in the island. The results show CO2 as the major dissolved gas specie in the groundwater from both galleries presenting a mean value of 260 cm3STP·L-1 and 69 cm3STP·L-1 for Fuente del Valle and San Fernando, respectively. The average δ13C-CO2 data (-3.9‰ for Fuente del Valle and -6.4‰ for San Fernando) suggest a clear endogenous origin as result of interaction of them with deep-origin fluid. A bubbling gas sample from Fuente del Valle gallery was analysed, obtaining a CO2 rich gas (87 Vol.%) with a considerable He enrichment (7.3 ppm). The isotopic data of both components in the bubbling gas support the results obtained in the dissolved gases, showing an endogenous component that could be affected by the different activity of the hydrothermal system. During the study period, an important seismic swarm occurred on October 2, 2016, followed by an increase of the seismic activity in and around Tenerife. After this event, important geochemical variations were registered in the dissolved gas species, such as dissolved CO2 and He content and the CO2/O2, He/CO2, He/N2 and CH4/CO2 ratios. These findings suggest an injection of fluids into the hydrothermal system during October 2016, a fact that evidences the connection between the groundwaters and the hydrothermal system. The present work demonstrates the importance of dissolved gases studies in groundwater for volcanic surveillance.
Impact of GIM uncertainties on the single-frequency PPP over the Brazilian region
Authors: Jerez Gabriel , Hernández-Pajares Manuel , Goss Andreas , Silva Crislaine , Alves Daniele , Monico João
Published: March 2022

The vertical total electron content (VTEC) is one of the main quantities to describe the state of the ionosphere. To dispose this information is important to mass market Global Navigation Satellite System (GNSS) users to correct the ionospheric delay for positioning. The VTEC values and the corresponding standard deviations are routinely provided in the so-called Global Ionosphere Maps (GIM), with time intervals of 2, 1 and 0.25 hours on regular grids with 2.5º resolution in latitude and 5º resolution in longitude. To determine the ionospheric corrections from the GIMs for positioning applications, a quadratic interpolation is typically applied to the VTEC grid values which generally does not take into account the VTEC uncertainties. In this context, the impact of the use of the VTEC standard deviation is assessed in the positioning domain, considering the GIMs of two different analysis centers. The impact of the VTEC uncertainties is analyzed by means of single-frequency precise point positioning (PPP), applied to four Brazilian GNSS stations in different regions, considering four scenarios: geomagnetic storm, low solar flux and high solar flux (equinox and solstice). The use of the VTEC uncertainties values provided a significant improvement coinciding with high solar flux, especially for stations in regions under the most intense ionospheric effect, with mean rates of improvements up to 47%.
Climate X: an interdisciplinary approach to projecting multiple climate-related risks and impacts
Authors: Burke Claire , Brennan James , Mitchell Hamish , Ramsamy Laura , Zeneli Markela , Kluza Kamil
Published: March 2022

With ever increasing risks and impacts from climate change, there is an urgent need for adaptation information which is relevant and useful to policy makers, businesses and the general public. At Climate X we use an interdisciplinary, impacts-motivated approach to adaptation; combining multiple climate and hazard models to give a holistic view of risk, and engaging end-users at every stage. Our first version product can project the risks and impacts of climate change-related pluvial and fluvial flooding, extreme heat, landslides, subsidence, and sea level rise, all at street level UK-wide. We quantify these risks and the financial costs they could incur under low (RCP 2.6) and high (RCP 8.5) emissions scenarios out to 2080. We deliver risk and impact assessments via an easy-to-use interface, along with relevant and decision-able risk summaries. Aligning robust science at scale with user requirements and expectations is not without its challenges. I will outline our approach to multi-hazard climate risk modelling, and discuss some of the successes and challenges we have had in developing a tool which is aligned with the needs of stakeholders, businesses and other end users.
Machine learning-derived predictions of river flow across Switzerland
Authors: Fluet-Chouinard Etienne , Aeberhard William , Szekely Eniko , Zappa Massimilano , Bogner Konrad , I. Seneviratne Sonia , Gudmundsson Lukas
Published: March 2022

The prediction of streamflow in gauged and ungauged basins is a central challenge of hydrology and is increasingly being met by machine learning and deep learning models. With increase in data volume and advances in modeling techniques, the capacity for deep learning tools to compete and complement physics-based hydrological models over a variety of settings and scales is still being explored. Here, we present initial results of the MAchine learning for Swiss (CH) river FLOW estimation (MACH-Flow) project. We train machine learning models on daily discharge data from 260 gauging stations across Switzerland covering the 1980-2020 time window. The river gauging stations we included have catchment areas ranging between 0.1-3000 km2, and average streamflow between 0.1-100 m3/second. We also test a range of predictor features including: air temperature, precipitation, incoming radiation, relative humidity, as well as a number of static catchment variables. We evaluated multiple model architectures of ranging complexity, from models focusing on runoff predictions over individual headwater catchments, such as Neural Network, Long short-term memory (LSTM) cells. We also investigate Graph Neural Networks capable of leveraging information from neighbouring stations in making point location predictions. Predictions are generated at gauging locations as well as over 307 land units used for drought monitoring. We benchmark and compare deep learning methods against two process-based hydrological models: 1) the PREecipitation Runoff EVApotranspiration HRU Model (PREVAH) used operationally by Swiss federal agencies and 2) the comparatively streamlined Simple Water Balance Model (SWBM). We compared the deep learning and physics-based models with regards to predicting daily river discharge as well as of low-flows during drought conditions that are essential for water managers and planners in Switzerland. We find that most deep learning methods with sufficient tuning and lookback periods can compete with the streamflow predictions from process-based models, particularly at gauging stations on larger non-regulated rivers where hydro-dynamic time lags are significant. Finally, we discuss the prospects for generating discharge predictions across all river segments of Switzerland using deep learning methods, along with challenges and opportunities to achieve this goal.
Ground motion emissions due to wind turbines: Results from two wind farms on the Swabian Alb, SW Germany
Authors: Gassner Laura , Ritter Joachim
Published: March 2022

Wind turbine (WT) ground motion emissions have a significant influence on sensitive measuring equipment like seismic monitoring networks. WTs permanently excite ground motions at certain constant frequencies due to the eigen modes of the tower and blades as well as the motion of the blades. The emitted waves have frequencies mainly below 10 Hz which are relevant for the observation of, e.g., local tectonic or induced seismicity. Furthermore, frequencies proportional to the blade passing frequency can be observed in ground motion data above 10 Hz, closely linked to acoustic emissions of the turbines. WTs are often perceived negatively by residents living near wind farms, presumably due to low frequency acoustic emissions. Therefore, similarities in ground motion and acoustic data provide constraints on the occurrence of such negatively perceived emissions and possible counter-measures to support the acceptance of WTs.

We study ground motion signals in the vicinity of two wind farms on the Swabian Alb in Southern Germany consisting of three and sixteen WTs, respectively, which are of the same turbine type, accompanied by acoustic measurements and psychological surveys. A part of the measurements is conducted in municipalities near the respective wind farms where residents report that they are affected by emissions. Additional measurements are conducted in the forests surrounding the WTs, and within WT towers. The wind farms are located on the Alb peneplain at 700-800 m height, approximately 300 m elevated compared to the municipalities. Results indicate that WTs are perceived more negatively in the location where the wind farm is closer to the municipality (ca. 1 km) and where other environmental noise sources like traffic occur more frequently. At the location more distant to the WT (ca. 2 km), even though more WTs are installed, residents are affected less. To improve the prediction of ground motion emissions, instruments are set up in profiles to study the amplitude decay over distance, which is linked to the local geology.

This study is supported by the Federal Ministry for Economic Affairs and Energy based on a resolution of the German Bundestag (03EE2023D).
Detection of extreme events from IASI observations
Authors: Vu Van Adrien , Boynard Anne , Prunet Pascal , Jolivet Dominique , Lezeaux Olivier , Henry Patrice , Camy-Peyret Claude , Clerbaux Cathy
Published: March 2022

The 3 IASI instruments on-board the Metop satellites have been sounding the atmospheric composition since 2006. Up to ~30 atmospheric gases can be measured from IASI spectra, allowing the improvement of weather forecasting, and the analysis and monitoring of atmospheric chemistry and climate variables.

The early detection of extreme events such as fires, pollution episodes, volcanic eruptions, industrial accidents, is key to take appropriate decisions regarding safety to protect inhabitants and the environment in the target areas. With IASI providing global observations twice a day in near real time, a new way for the systematic and continuous detection of exceptional atmospheric events to support operational decisions is possible.

In this work, we explore and improve a method for the detection and characterization of extreme events using the recorded spectra, which relies on the principal component analysis (PCA) method. We assess this PCA-based system by analysing IASI raw and reconstructed spectra along with their differences (residuals) for various past and documented extreme events. The benefits and limitations of this approach are discussed with comparison with available CO and SO2 IASI products. A methodological innovation, based on the refined analysis of extreme residuals (outliers) for the detection of fires, volcanic eruptions and pollution event is proposed, and could be used for the automatic and systematic detection of unexpected events.
Spatially assessing the role of glacier and snowmelt for meeting environmental flow requirements in a high mountain Andean catchment
Authors: Marinelli Bryan , Lutz Arthur , Breuer Lutz , Weeser Björn , Correa Alicia
Published: March 2022

As climate change continues to alter the dynamics of hydrological flows, quantifying the associated environmental impacts become more and more vital.

Here we present a study focusing on analyzing the spatial and temporal distribution of flow components, particularly the contributions of glacier melt, snowmelt, rainfall-runoff, and groundwater flow to river discharge in the high mountain Santa River catchment. The catchment is located in the Cordillera Blanca of Peru, the region with the largest glacier cover in the tropics, and has an area of 12,279 km², an average discharge of 133 m3/s, and average annual precipitation of 750 mm.

We used the spatially distributed cryospheric-hydrological model SPHY, forced with W5E5 meteorological data (1979 - 2019) to simulate daily spatial discharge components. Additional static inputs such as a digital elevation model, land use maps, soil hydraulic properties, and glacier extent, thickness, and debris cover were collected from freely available remote sensing-based datasets.

The model runs at a spatial resolution of 500 x 500 meters with daily time steps. Data from 1995 to 1997 were used to spin up the model. Calibration (1998 - 2001) and validation (1998 - 2018) were performed through the comparisons of simulated and observed discharge. The model's performance was evaluated by the percent bias (1.5%; -7.2%), Nash-Sutcliffe efficiency (0.81; 0.65), and R2 (0.82; 0.68). With the best runs, the complete 41 years were simulated.

Further analysis evaluates how glacier melt and snowmelt compensate the discharge amount in dry periods to meet environmental flow requirements and the derived environmental services chain.

The overall outcome of this assessment will define spatially distributed compensated zones, ensuring an informed management of glacier covered watersheds, as well as open up new horizons to better understand, and mitigate, the impacts of climate change.
Groundwater temperature study - Subsurface Urban Heat Island in the city of Wrocław (Poland)
Authors: Blachowski Jan , Hajnrych Monika
Published: March 2022

The average air temperature in the world has increased recently. Over the past 20 years, the global average has increased by 0.6 C and continues to increase [1]. In south-western Poland, in Wrocław, for the same period, the recorded increase in the average air temperature is approx. 0.5 °C [2]. The reason for this phenomenon is human activity. The process of urbanisation has created another phenomenon called the Urban Heat Island (UHI), which can be studied analysing for example the Land Surface Temperature (LST). The combined effect of the UHI and climate change can influence groundwater temperature by penetrating underground. The phenomenon of elevated groundwater temperatures is called the Subsurface Urban Heat Island (SUHI) [3,4]. While the Urban Heat Island effects is generally negative and widely investigated, the higher groundwater temperature may have positive aspect, such as e.g. use in heat pumps. The SUHI phenomenon is less understood than the UHI one.
This presentation focuses on the spatial distribution of temperature in shallow aquifers in the city of Wroclaw (SW Poland) developed with various interpolation techniques and based on measurements made in a network of piezometers in the 2004-2005 period. In total 67 locations have been measured and the temperatures recorded varied between 1.1 °C and 24.5 °C with the average of 13.2 °C. The data has been processed with the IDW, spline and kriging interpolation methods. The groundwater temperature distribution was analysed spatially, taking into account the then land use and location of technical infrastructure. In addition, an attempt has been made to compare the distribution of groundwater temperature with the Land Surface Temperature. The latter was determined based on Landsat 5 satellite imagery.
The interpolated groundwater temperature maps have made it possible to analyse and present graphically the spatial distribution of temperature and link it to the LST UHI for the analysed period.

Bibliography:

[1] Global Climate Change https://climate.nasa.gov/ (accessed on 11 January 2022)

[2] Polish climate 2020. Institute of Meteorology and Water Management, National Research Institute. Available online: https://www.imgw.pl/sites/default/files/2021-04/imgw-pib-klimat-polski-2020-opracowanie-final-pojedyncze-min.pdf. (accessed on 11 January 2022)

[3] Luo Z., Asproudi C., Subsurface urban heat island and its effects on horizontal ground-source heat pump potential under climate change, Applied Thermal Engineering, Volume 90, 2015, doi: 10.1016/j.applthermaleng.2015.07.025.

[4] Zhu, K., Bayer, P., Grathwohl, P., and Blum, P. (2015), Groundwater temperature evolution in the subsurface urban heat island of Cologne, Germany, Hydrol. Process., 29, 965– 978, doi: 10.1002/hyp.10209
The EMIC wave-driven proton precipitation and related effects on the ionosphere
Authors: Tian Xingbin , Yu Yiqun , Ma Longxing
Published: March 2022

Protons of tens of keV can be resonantly scattered by EMIC waves excited in the magnetosphere and further precipitate down to the upper atmosphere. In this study, we show a case event that shows direct linkage of the EMIC waves, proton precipitation, and ionospheric ionization using space-borne and ground-based measurements. On Oct 11, 2012, the POES observed that the precipitating flux of the proton much larger than that of the electrons in the night sector around magnetic latitude of 65°. Around the same time and location, ground-based magnetometer detected clear signature of EMIC waves, indicating the causal relation to the proton precipitation. We further simulate the impact of this tens of keV proton precipitation on the upper atmosphere, and found good agreement with PFISR observations of electron density and conductivity. On the other hand, the large ionization rate cannot be accounted for by the electron precipitation at that location. This study shows a clear evidence of the precipitating coupling processes within the magnetosphere-ionosphere system.
Prediction of flow intermittence in Drying River Networks using a process-based hydrological model
Authors: Künne Annika , Mimeau Louise , Branger Flora , Kralisch Sven
Published: March 2022

Intermittent rivers and ephemeral streams (IRES) account for about half of the world’s river
networks and are considered to increase under climate change and growing anthropogenic water
use. However, the hydrological mechanisms that control the spatio-temporal flow patterns in IRES
and their effects on the expansion and contraction of stream segments are not fully understood.
Discharge measurements mainly exist for gauging stations, which are often located downstream and
in the rivers’ main stems. They are often less impacted by flow intermittence than headwaters and
smaller river channels. In consequence, impacts of climate change and anthropogenic alterations on
hydrological process dynamics in IRES cannot easily be analysed, neither the influences of climate
change and human water use on IRES be quantified.
Within the framework of the Horizon 2020 project DRYvER on Drying River Networks and
Climate Change, we try to tackle this challenge by developing methods and tools using the JAMS
modelling framework and J2K model family to assess hydrological process interactions at high
spatial and temporal resolutions, which include the scale of small reaches (about 50 ha catchment
size). For that purpose, we developed process-based hydrological models for six mesoscaled river
basins between 200 km² and 350 km² in different European countries (Croatia, Czech Republic,
Finland, France, Hungary, Spain). At the same time, we used data from field measurements
and a citizens science application to validate our models at the reach scale. In this study we
analyse the ability of our hydrological model to represent observed temporal and spatial dynamics
of flow intermittence at high resolution, and develop adaptations that allows using these models
in an upscaling step to estimate the impacts of future climatic changes and anthropogenic water
consumption on flow intermittence all over Europe.
Modelling soil structure dynamics and nitrous oxide emissions in compacted soils by animal treading
Authors: Romero-Ruiz Alejandro , Coleman Kevin , Segura Carmen , Cardenas Laura , Milne Alice , Whitmore Andrew
Published: March 2022

Soil compaction is a form of soil degradation that adversely impacts soil mechanical and hydraulic properties, potentially affecting productivity and is often linked to increases in nitrous oxide emissions. However, we lack a quantitative understanding of the extent and environmental impacts of soil compaction. This is partially due to gaps in our knowledge of how compaction impacts soil physical properties spatially and temporally, how it impacts soil's hydrological functioning and how these impacts ultimately modify nitrification and denitrification in the soil. We propose to address this challenge by embedding a new? model of soil structure dynamics into an agro-ecosystem modelling framework to explicitly account for soil compaction impacts on soil functions such as soil moisture dynamics, plant growth and GHG emissions. We tested this model to assess the effect of soil compaction by animal treading in livestock-grazing systems. We considered random movement of cattle in a confined area that is discretized in square cells with given soil bulk density and saturated hydraulic conductivity. Changes in these properties in response to animal treading are then inferred using a soil rheology model based on Bingham's law. We modeled five two-month long grazing seasons in consecutive years using 18 years of weather data from the North Wyke experimental platform in Devon, United Kingdom. Our model predicts an increase of bulk density of up to 20% and a decrease in hydraulic conductivity of up to 95% due to animal treading. Such compaction-induced changes in soil pore space and related hydraulic functions led to a relative increase in N2O emissions from the compacted areas of up to 200% and a related decrease in yield of up to 15%, which is in agreement with ranges reported in the literature. By providing a mechanistic framework that calculates the impacts of soil management on soil properties and functions, our work advances the ability to test management strategies that might help to ameliorate the environmental impact of animal treading in grasslands.
Boundary and elastic parameter sensitivity kernels for a receiver function waveform misfit in a global earth.
Authors: de Jong Janneke , Paulssen Hanneke , Trampert Jeannot
Published: March 2022

The receiver function method is widely used in seismology to study the characteristics of Earth’s major discontinuities. Ray theory and an assumed planar incoming wave are often used to estimate which regions of the mantle, crust and discontinuity contribute to the receiver function. To test the validity of these simplifying assumptions, we derived the adjoint source of a receiver function waveform misfit and applied the adjoint method on synthetic teleseismic receiver functions to calculate their sensitivity kernels of both subsurface velocity parameters in the mantle and boundary topography on the discontinuity. Here we focused on the P660s-phase and the 660-discontinuity. We observe a strong sensitivity to the wavefield far away from the discontinuity, particularly for the Vp sensitivity kernel. It has a strong sensitivity to the Fresnel zone of the P660s-phase before conversion, but also to the scatterers of the direct P-wave and other phases that arrive within the considered time window. This implies that mapping the observations solely to the P660s ray paths and ray-theoretical conversion points might be too simplistic and lead to inaccuracies in the conclusions. In general, a receiver function has a strong dependance on the background velocity models everywhere in the mantle. The boundary topography kernels have a sensitivity predominantly to the area near the conversion point. The diameter of the high-sensitivity area is roughly 300 km for an event with a source halftime of 5 s. Relatively weak sensitivity to the source region and the scatterers of the direct P-wave are observed in the boundary kernels as well. Our results show that using the adjoint method on receiver function waveforms to invert for mantle structure and boundary topography is possible and advisable. It allows for an automatic consideration of all contributing phases and scatterers arriving within the chosen time window, which is important for correctly dealing with velocity perturbations. The boundary kernels demonstrate that the receiver functions’ sensitivity to topography is concentrated to the region around the ray theoretical conversion point.
How Hydrothermal Cooling and Magmatic Sill Intrusions Control Flip-Flop Faulting at Ultraslow-Spreading Mid-Ocean Ridges
Authors: Glink Arne , Hasenclever Jörg
Published: March 2022

The young oceanic lithosphere created at mid-ocean ridges (MORs) is shaped by a complex interplay of magmatic, tectonic and hydrothermal processes. At decreasing melt budgets and (ultra)slow spreading rates, the tectonic spreading mode changes from normal fault dominated to detachment faulting. We investigate an endmember type of detachment faulting, the so-called “flip-flop” detachment mode, observed exclusively at almost amagmatic sections of ultraslow-spreading MORs (e.g. Southwest Indian Ridge 62°E to 65°E): Without significant melt supply, extension in the hanging wall of active detachments cannot be compensated by magmatic accretion. The fault zone therefore migrates across the ridge axis towards the hanging wall side until it is superseded by a new on-axis fault of opposite polarity. Using a steady-state temperature field, a recent numerical study shows that an axial temperature maximum is essential to trigger flip-flop faults by focusing flexural strain in the footwall of the active fault. However, ridge segments with very low melt budget are more likely to be in a transient thermal state controlled, at least in part, by the faulting dynamics themselves.

 

In our study, we investigate (1) the processes having first order control on the thermal structure of the lithosphere, (2) their respective feedbacks on its mechanical evolution, and (3) how their interplay can explain observed faulting patterns. We present results of 2-D thermo-mechanical numerical modelling including serpentinization reactions and dynamic grain size evolution. The model features a novel form of parametrized hydrothermal cooling along fault zones as well as the thermal and rheological effects of periodic sill intrusions.

 

We find that the interplay of both enhanced hydrothermal cooling along the active fault zone and periodic sill intrusions in the footwall are essential for entering the flip-flop detachment mode. Hydrothermal cooling increases the temperature difference between the active detachment and its surroundings. Fault zone cooling thereby pushes the temperature maximum into the footwall, while intrusions near the temperature maximum further weaken the rock and facilitate the opening of new faults with opposite polarity. Our model allows us to put constraints on the magnitude of both processes, and we obtain reasonable melt budgets and hydrothermal heat fluxes only if both are considered. The parameter range, where flip-flop faulting dominates, is bounded by other faulting modes, including symmetric modes which provide alternative explanations for the observed sea floor characteristics.
Deformation, uplift and exhumation across the northern sectors of the Iranian Plateau: insights from low-temperature thermochronology data and intermontane basins fill units
Authors: Ballato Paolo , Balestrieri Maria Laura , Dunkl Istvan , Balling Philipp , Paknia Mohammad , Heidarzadeh Ghasem , Biralvand Masoud , Zeilinger Gerold , Ghassemi Mohammad , Faccenna Claudio , Strecker Manfred
Published: March 2022

The Iranian Plateau represents a NW-SE striking, elongated, elevated (mean elevation of ~1.8 km), arid, mostly internally drained (~65 % of its area) and aseismic morphotectonic feature of the Arabia-Eurasia collision zone. With a crustal thickness up to ~65 km, the southern plateau margin includes the High Zagros Mountains and the plate suture zone. The northern plateau margin, instead, consists of the Urumieh-Dokhtar Magmatic Zone and the western Alborz-Talesh Mountains from SE and NW Iran, respectively, which exhibit a crustal thickness ranging from 40 to 50-55 km. The plateau interior is characterized by a low-topographic relief morphology with six major, mostly internally drained intermontane sedimentary basins. The backbones of these basins are mainly represented by the Sanandaj-Sirjan Zone. Plateau uplift commenced after ~17 Ma, as documented by the occurrence of Lower Miocene shallow-water marine sediments of the Qom Formation within the plateau interior. Although the Iranian Plateau represents the second largest collisional plateau after Tibet, the chronology of the events and the mechanisms that built it are poorly constrained.

In this study, we combine a new low-temperature thermochronologic dataset including apatite fission- track and apatite (U-Th-Sm)/He ages from the northern plateau sectors and its interior with structural and stratigraphic data from different intermontane basins and literature thermochronology data. Combined, this information shows that after a mild phase of post late Eocene contractional deformation, collisional deformation started in the early Miocene along the plate suture zone to the south and in the middle Miocene (~16 Ma) in the Talesh-Alborz Mountains to the north. Subsequently, around 12-10 Ma, deformation jumped in the plateau interior over a rather large area including the Urumieh-Dokhtar and Sanandaj-Sirjan zones, apparently without a specific pattern of propagation. Upper plate deformation occurred mostly through the reactivation of older NE-dipping structures that led to the topographic growth of several mountain ranges spanning a wavelength of ~50-60 km. This was associated with the compartmentalization of the upper plate and the development of different intermontane basins. There, basin filling processes inhibited intrabasinal deformation and faulting along the major range-bounding faults producing the smoothed, low-relief landscape typical of an orogenic plateau.

Combined, these results provide new information concerning the mechanisms and the timing of the lateral, orogen-perpendicular, growth of the Iranian Plateau
How horizontal current shear affects the remote sensing of current depth profiles
Authors: Weichert Stefan , Smeltzer Benjamin K. , Ellingsen Simen Å.
Published: March 2022

Detailed knowledge of the subsurface current in the ocean environment allows for more accurate modelling of, e.g., exchange of mass and heat with the atmosphere. Measuring the vertical profile of the current in situ poses a range of costs and difficulties. Therefore, methods were developed to infer this information from measured Doppler shift velocities, i.e., from changes in the waves’ phase velocities owing to the background current, which are obtainable from, e.g., optical or radar imaging of the surface. Notably, the “polynomial effective depth method” (PEDM), due to Smeltzer et al. [1], was shown to be a promising candidate. These methods, however, typically assume the current to be uniform in the horizontal plane.

In this work we study the effects of slow horizontal variations on the accuracy of the extracted Doppler shifts. Synthetic data is generated by propagating waves from still water into a region of horizontal and vertical shear, where the propagation is governed by the dispersion relation as given by Steward and Joy [2]. The numerically generated wave fields then serve as the raw video data for the extraction of current-induced Doppler shifts whence the vertical shear current is estimated and compared to the prescribed one.

The simulation of the wave fields is based on the method of characteristics. Given a wave spectrum in the quiescent region, for each wavelength, a phase field is obtained from propagating waves along rays. These fields then form the basis for constructing a “movie”.

Results for different horizontal velocity fields and wave spectra are compared to investigate their effect on the accuracy of the vertical profile retrieved by the PEDM.

[1] Smeltzer, B. K., Æsøy, E., Ådnøy, A., & Ellingsen, S. Å. (2019). An improved method for determining near-surface currents from wave dispersion measurements. Journal of Geophysical Research: Oceans, 124, 8832– 8851.

[2] Stewart, R. H. & Joy, J. W. (1974). HF radio measurements of surface currents. Deep Sea Research and Oceanographic Abstracts, 21, 1039-1049
BepiColombo at Mercury: First close-in magnetic field measurements from the southern hemisphere
Authors: Heyner Daniel , Carr Chris , Auster Uli , Richter Ingo , Kolhey Patrick , Exner Willi , Mieth Johannes , Plaschke Ferdinand , Pump Kristin , Wicht Johannes , Langlais Benoit , Berghofer Gerhard , Schmid Daniel , Baumjohann Wolfgang , Fischer David , Horbury Timothy , Magnes Werner , Masters Adam , Slavin Jim , Glassmeier Karl-Heinz ,   MPO-MAG Team
Published: March 2022

The internal magnetic field of Mercury is best described by a northward offset dipole with almost zero obliquity. Its offset, weakness, axisymmetry and lack of secular variation still poses a challenge to dynamo theory. After NASA’s Mariner 10 flybys in the 1970’s and MESSENGER’s orbital mission in 2011-2015, BepiColombo performed a flyby at Mercury in October 2021. For the first time, magnetic field measurements are obtained from the southern hemisphere by the fluxgate magnetometer MPO-MAG. We will present an overview of the flyby data and compare the new in-situ data to magnetospheric models obtained from the previous missions to the innermost terrestrial planet. Does the flyby data reveal any secular variation? Has the dipole offset changed? These are some of the questions we will discuss with this unprecedented magnetometer data. We will close with a discussion on what is to be expected from the orbital phase of BepiColombo. 
Spatial distribution of surface water losses from urban areas across the contiguous United States
Authors: Palazzoli Irene , Montanari Alberto , Ceola Serena
Published: March 2022

Human pressure on surface water is increasing globally, especially on river systems. Future scenarios of urban population growth anticipate an overexploitation of surface water resources in the proximity of cities, which in turn will produce environmental, social, and economic impacts whose effects are going to influence increasingly larger areas. Therefore, it is crucial to gain a better understanding of the dynamics of interaction between human settlements and surface water, to find a balance between urban planning and water management policies that ensure water conservation and ecosystem protection. In this study we assess the driving role of urban areas in the spatial distribution of surface water losses across the contiguous United States (CONUS). In particular, we analyze the frequency of occurrence of surface water loss as a function of distance from urban areas using remote sensing data and we define a distance decay model that reproduces the observed spatial behavior. We find that the frequency of surface water loss declines as the distance from urban areas increases and we successfully model this spatial trend with an exponential probability distribution function. Moreover, we observe distinct decay patterns of the frequency of occurrence of surface water loss associated to the main climatic conditions of the CONUS, as surface water losses are more concentrated around urban areas in regions with a temperate and continental climate, while they result to be more widespread over greater distances in regions with an arid climate.
Stress path effects on the shearing behaviour of root-reinforced soils
Authors: Leung Anthony , Karimzadeh Ali Akbar
Published: March 2022

Plant roots increase soil shear strength. The increase primarily depends on the relative direction of the root orientation and the principal strains/stresses of the rooted soils. Most of the published work focused on the direct-shear behaviour of rooted soil, of which both the magnitude and direction of the principal stresses could not be controlled nor measured. Indeed, in the scenario of slopes, the stress path experienced by direct-shear soil samples and the associated shear strength parameters (e.g. cohesion and friction angle) derived are only relevant to the soil elements that are sheared in the direction parallel to the slope. The shearing behaviour of rooted soil following other stress paths, such as triaxial compression (near slope crest) and triaxial extension (near slope toe), have rarely been investigated. In this study, we conduct a comprehensive laboratory test campaign to study the effects of stress paths on the shearing behaviour including stress-strain (hardening and softening) on coarse-grained soils reinforced by the roots of vetiver grass (Chrysopogon zizanioides). Root-reinforced soil samples prepared to different root volume ratios (RVR; defined as the ratio of total root volume to total specimen volume) were subjected to undrained triaxial compression and extension stress paths at different confining stresses. We will present key experimental evidence to demonstrate how the different stress paths and RVRs affect the stress–strain behaviour of the soil. We will also present the effects of stress path on cohesion and friction angle and discuss the strength anisotropy of the rooted soils. The new test results will shed light on the selection of plants of desirable root architecture at different slope locations (i.e. crest, mid-slope, toe) to maximise the root reinforcement effects to shallow soils.
Groundwater recharge modeling – the importance of distributed soil information in hydrological models 
Authors: Zeitfogel Hanna , Herrnegger Mathew , Feigl Moritz , Schulz Karsten
Published: March 2022

Spatially distributed soil information as input for hydrological models has the potential to improve the representation and physical realism of spatio-temporal hydrological processes. Since spatially distributed soil information is often not available, lumped parameters are frequently used in hydrological models to describe soil functions. However, especially the modeling of hydrological processes in the vadose zone – and consequently groundwater recharge – requires information on soil hydraulic properties. The main objective of this study is the prediction of future groundwater recharge rates for the extent of Austria under changing climate conditions. To reach this goal, we use Machine Learning (ML) based soil hydraulic maps as a basis for the parameterization of the COntinuous SEmi-distributed RunOff model (COSERO).

For the spatial prediction of the soil parameters, XGBoost, a boosting ML-algorithm, was trained with soil hydraulic maps of the federal state of Lower Austria and available environmental raster datasets (e.g. climate data, digital elevation model, landcover etc.). Based on the Austrian wide available environmental covariates, the trained XGBoost model was then used to predict relevant soil hydraulic properties for the whole area of Austria (approx. 83 900 km²) at a target resolution of 1 x 1 km².

For our hydrological model set-up, we rescale the predicted soil hydraulic properties into the model parameter range and domain. After parameter optimization, i.e. in our case scaling the mean and thereby keeping the spatial patterns of the parameters, the conceptual rainfall-runoff model COSERO simulates spatially distributed discharge for the study area. We compare our model results to simulations of a model version using lumped soil parameters to assess the differences in the spatial distribution of groundwater recharge rates. Additionally, we analyze the quality of discharge simulations depending on the respective parameterization of the model. Overall, the results show an increased performance when using distributed soil hydraulic properties.

In summary, this study demonstrates the importance of considering the variability of soil information in a hydrological model framework and evaluates the suitability of implementing digital soil mapping products in groundwater recharge modeling.
Anisotropy of magnetic susceptibility and hysteresis parameters for natural magnetite particle assemblages: Micromagnetic analysis of focused-ion-beam nanotomography data with MERRILL
Authors: Nikolaisen Even S. , Harrison Richard J. , Fabian Karl , McEnroe Suzanne A.
Published: March 2022

Three-dimensional shapes of 68 magnetite grains in pyroxene and 234 magnetite grains in plagioclase, were obtained by “slice-and-view” focused-ion-beam nanotomography (FIB-nt) on mineral separates from the Bushveld Intrusive Complex, South Africa. Electron backscatter diffraction (EBSD) determined the orientation of the magnetite inclusions relative to the crystallographic directions of their silicate hosts. For each particle, hysteresis loops in 20 equidistributed field directions were calculated by the finite-element micromagnetic code MERRILL. For each direction, the averages over the particle ensemble were compared to corresponding hysteresis loops measured with a vibrating sample magnetometer (VSM) on silicate mineral separates from the same samples. FIB-nt combined with micromagnetic modelling allows to explore the mechanisms controlling the magnetic anisotropy for each individual particle and to analyze the combined effect for bulk magnetic properties. This combination is of interest for anyone who interprets magnetic anisotropy because it helps understanding how domain states and crystal alignment in natural samples influence the measured anisotropy. Our results demonstrate that natural particle shapes, their orientations and domain states control the anisotropy of magnetic remanence, coercivity and susceptibility in natural particles. We can show for our specific examples, how the connection between mineral texture and magnetic anisotropy depends on specific domain states. Our data explain why natural magnetite particles at the transition between single-domain and single or multiple vortex states do not always follow the relation between axis orientation and  magnetic anisotropy which is theoretically expected for simple particle shapes.
Modeling Ocean Biogeochemistry of the Mediterranean Sea at the Last Glacial Maximum
Authors: Six Katharina , Mikolajewicz Uwe
Published: March 2022

Present day Mediterranean Sea (MedSea) is an oligotrophic semi-enclosed basin.  Nutrient supply by rivers, net nutrient export through the Strait of the Gibraltar and the basin-wide circulation create a biological desert. Sediment core records, however, indicate periods of higher production during paleo times.

To gain insight into biogeochemical conditions during the Last Glacial Maximum (LGM), we apply a regional ocean-biogeochemistry model of the Mediterranean Sea.  A consistent forcing is available from a transient simulation with an Earth System Model (ESM) over 22,000 years based, among others, on an ice sheet reconstruction.  The ESM run provides atmospheric forcing fields, being downscaled to the regional setup, temperature and salinity conditions at the open western boundary in the Atlantic, and river runoff.  Nutrient concentrations of river discharge and at the Atlantic boundary are set to present-day estimates.  The automatic bathymetry adjustment to account for sea level variations due to meltwater fluxes is adopted from the ESM simulation. The LGM simulation starts at 22 ka to allow for a 1000 yr spinup run with transient forcing. The LGM period results are compared to a present-day simulation based on the same consistent ESM forcing.  

Colder temperatures and thus lower basin-wide evaporation, as well as a shallower sill depth at the Strait of Gibraltar, lead to lower baroclinic watermass exchange between the MedSea and the Atlantic. The zonal overturning circulation is more sluggish during the LGM than present day.  River discharge to the MedSea increases by 35% during the LGM, causing an increased net primary production near the river mouths.  Despite a higher nutrient inventory of the MedSea at the LGM, net primary production of the entire MedSea is lower than present day. Colder LGM temperatures reduce phytoplankton growth rates and increase the remineralisation length scale.

More characteristics of LGM biogeochemistry are presented and their drivers will be disentangled, also including additional sensitivity studies on changes in bathymetry.        