bluuebunny/crossref_metadata_2025 huggingface dataset:
Electromagnetic radiation following the first return strokes of negative and positive cloud-to-ground lightning flashes
Authors: Kolínská Andrea , Kolmašová Ivana , Santolík Ondřej , Defer Eric , Pedeboy Stéphane , Lán Radek
Published: March 2022

All evolution stages of cloud-to-ground (CG) lightning flashes, both positive (+CG) and negative (-CG), generate electromagnetic radiation, which can be used for their investigation. We focus on the electromagnetic activity immediately following the first return stroke (RS). We combine measurements of the broadband receiver BLESKA and the lightning mapping array (LMA) network SAETTA, capable of detecting sources of narrowband very high frequency (VHF) radiation. The French lightning location system Météorage provided us with the information about 2D location, polarity and peak currents for studied CG and intracloud (IC) discharges. From our data collected in the northwestern Mediterranean region from September to December 2015, we have selected and investigated the electromagnetic activity following 16 +CG and 38 -CG flashes.

Using the data from individual SAETTA stations we found that 36 -CG flashes exhibited a fast decrease in the counts and in the power of VHF radiation sources immediately after the RS pulse. The maximum count of 2000 VHF radiation sources was detected by the closest SAETTA station at an average time delay of 66 μs after the RS pulse peak. At a delay of 1.85 ms after the RS pulse peak or sooner, the VHF radiation rate decreased below 1500 VHF radiation sources, with the median value of this time equal to 195 μs, and kept decreasing.

In the case of all inspected +CG flashes, we observed an unexpectedly fast increase in the counts of the VHF radiation sources and their power after the RS pulse. Up to 161.95 ms after the RS pulse, the VHF radiation rate decreased below 1500 VHF radiation sources, with the median value of this time equal to 34.53 ms, much longer than in case of –CGs. At the same time, we observed a visible sequence of bipolar pulses lasting up to 50 ms in the magnetic-field waveforms recorded by BLESKA, with the amplitude of the biggest pulse varying from 2 to 10 nT.

This observed longer presence of VHF radiation after +CG flashes may be caused by a potential difference between the end of neutralized RS channel and the positive charge layer in the thundercloud in case of +CGs, which might result in a new electrical breakdown. Then a stepwise propagation of a new negative leader inside the thundercloud is possible, emitting electromagnetic radiation in a wide range of frequencies. This radiation can be detected by narrowband LMA stations in the form of VHF radiation sources, same as by a broadband receiver in the form of pulses.
Accuracy of locating earthquakes and landslides in sparse seismic network with ambient noise Empirical Green’s Functions
Authors: Wang Shuofan , Ni Sidao , Xie Jun , Zeng Xiangfang
Published: March 2022

Earthquakes and landslides threaten the safety of human life and property. Fast and accurate location of earthquakes and landslides is critical to disaster mitigation and early warning of the secondary hazards. Hazards locating is a difficult issue in a remote region with sparse seismic network due to low resolution of the velocity structure model. Green’s functions from ambient seismic noises contain the information characterizing the anomalous velocity structure along the propagation path, and it can be used to calibrate effects due to the uncertainty of velocity structure, thereby improving the hazard location accuracy. In this study, we select the 2008 Wudu Ms5.5 earthquake, China, and a large landslide occurred in Nuugaatsiaq, Greenland, on 17 June 2017 as examples, to assess the accuracy of the relative location method based on Green’s functions from ambient seismic noises. The location result of the landslide is about 2.5 km away from the site given by satellite image, which is better than the result based on traditional location method, with a deviation up to ~17 km. Subsequently, we test some impact factors of the location accuracy via the 2008 Wudu earthquake, such as the epicentral distance of the reference stations and the networks with different sparseness. It shows that using a reference station within 30 km and about 4 remote stations for relocation, the relocation accuracy is about 5 km. Our results demonstrate that this algorithm can provide accurate location of earthquake and landslide with seismographic stations in global and regional networks, thus providing timely assistance to early warning of secondary hazards.
Low-cost and smartphone GNSS sensors: current capabilities and perspectives for seismic and tropospheric monitoring applications
Authors: Hohensinn Roland , Stauffer Raphael , Herrera Pinzón Iván Darío , Möller Gregor , Aichinger-Rosenberger Matthias , Rossi Yara , Pan Yuanxin , Kłopotek Grzegorz , Soja Benedikt , Rothacher Markus
Published: March 2022

In recent years, dual-frequency GNSS chipsets became available on the mass market. The ongoing developments in sensor and processing technologies steadily improve the positioning performance so that nowadays sub-decimeter accuracies can be achieved with such devices, even in real-time. Thus these sensors become a powerful, inexpensive choice for equipping or densifying existing GNSS monitoring networks. Station densification can be of significant added value for earthquake early warning systems, assimilation of GNSS water vapor estimates into numerical weather prediction models and the detection of severe weather events. Even if somewhat noisier, smartphone data can be used for GNSS-based remote sensing purposes as well.

This contribution is twofold, and focusses on both, the current capabilities and the perspectives of these GNSS low-cost technologies for such remote sensing applications. In the first part we highlight the accuracy of PPP-enabled seismic and tropospheric monitoring using low-cost loggers and stations developed in-house. We show that differential smartphone GNSS observations on short- and medium-length baselines can be used to sense the state of the regional troposphere. In the second part, we present first results on the performance of the u-blox D9S application board, which enables highest precision by PPP-RTK with ambiguity resolution, and the feasibility of high-precision positioning is assessed for long baselines involving smartphone data as well. Finally, we briefly discuss the potential of data-driven methods for mitigating multipath, which is still one of the main error sources when using equipment of low quality. Concerning the GNSS processing, we rely on further-developed versions of open-source and commercial GNSS software packages. Regarding sensor technology, u-blox chips -- which are currently deployed in our self-sufficient GNSS stations -- are used together with different low-cost and medium-grade GNSS antennas (both, patch and recent helical-type low-cost antennas).

We conclude that low-cost GNSS sensor technology is on the way to satisfy the same demands in accuracy as geodetic-grade equipment -- centimeter-level accuracy can be obtained, even in real-time. New possibilities for station densifications arise by employing low-cost, autonomous stations or by crowdsourcing of GNSS data with smartphones. These observations can aid in resolving small-scale structures in the atmosphere, or for a quick detection and localization of geohazards.
Drivers of surface winds variability in Antarctica
Authors: Davrinche Cécile , Agosta Cécile , Amory Charles , Kittel Christoph , Orsi Anaïs
Published: March 2022

Surface winds in Antarctica are amongst the strongest and most persistent winds on Earth. They play a key role in defining the surface climate.
While new proxys are being developed in order to understand their past evolution, it is a crucial to understand the processes controlling their temporal variability. 

Here, we investigate the drivers of surface winds variability in East Antarctica at present-day. To do so, we separate the wind-speed temporal variations from daily outputs of the regional atmospheric model MAR at 35 km resolution into different terms of the dynamic equations.
 Our study focuses on a transect running through Adelie Land, where numerous meteorological measurements are being conducted.  
 
We identify the combination of terms that correlates best in winter to the wind speed in this region.
On the Antarctic plateau, wind speed is controlled by the balance between large-scale pressure gradient acceleration and turbulence.
At mid-slope, the katabatic term is the greatest but does not correlate with wind-speed. One of the reason that explains this result is that increasing positive katabatic forcing is counteracted by increasing turbulence (negative term, deceleration effect). Consequently, the combination of the turbulence and katabatic terms correlates slightly better to wind-speed intensity.

At the coast, wind-speed intensity mainly results from the katabatic and thermal wind terms. 

As a conclusion, the study of a smaller number of contribution terms in the budget equation will help evaluating the drivers of past and future evolution of wind speed in this region.
Observations by ASIM of Terrestrial Gamma-ray Flashes accompanied by Elves
Authors: Bjørge-Engeland Ingrid , Østgaard Nikolai , Mezentsev Andrey , Skeie Chris A. , Sarria David , Lapierre Jeff , Lindanger Anders , Neubert Torsten , Marisaldi Martino , Lehtinen Nikolai , Chanrion Olivier , Ullaland Kjetil , Yang Shiming , Genov Georgi , Christiansen Freddy , Reglero Victor
Published: March 2022

Terrestrial gamma-ray flashes (TGFs) are short and highly energetic bursts of photons, produced in association with lightning in thunderstorms. Elves are rapidly expanding rings of optical emissions, with radii of several hundred kilometers, produced when electromagnetic pulses from lightning hit the base of the ionosphere. The Atmosphere-Space Interactions Monitor (ASIM) detects both TGFs and Elves, sometimes simultaneously. Here, we present a study of observations where TGFs are accompanied by Elves. The optical signatures from Elves are identified from measurements by the ASIM UV photometer. Using ground-based lightning location networks, we find associated sferic detections to these events, placing them mainly over oceans and in coastal regions. Using sferic detections by GLD360, we compare the peak currents of the lightning associated with the TGF-Elve pairs to peak currents associated with other TGFs detected by ASIM, as well as with lightning in general. We show that the TGFs accompanied by Elves are among the shorter TGFs detected by ASIM, and they are associated with very high peak currents of typically several hundred kA.
Grain-scale equilibrium reactions guide fluid-driven eclogitization of dry crustal rocks
Authors: John Timm , Zertani Sascha , Vrijmoed Johannes C. , Brachmann Caroline , Plümper Oliver
Published: March 2022

When a fluid is introduced into dry rocks at high-pressure conditions, it acts as a catalyst and facilitates re-equilibration. This often promotes weakening and subsequent ductile deformation. Here, we present a detailed micro-structural and mineral chemical study of eclogitization of initially dry continental crustal rocks in the absence of ductile deformation. The studied sample features an incomplete (fluid-induced) transition from lower crustal granulite to eclogite, and the transition is fully preserved. None of the mineral phases show any signs of ductile deformation, indicating that the transformation was entirely static. Material transport during the reaction was limited to the availability of fluids. Detailed analysis of the local assemblages along the transect reveals that the reaction occurs in three distinct steps: The plagioclase-plagioclase grain boundaries were the first to re-equilibrate followed by clinopyroxene-plagioclase and garnet-plagioclase grain boundaries. Lastly, the grain boundaries that included only garnet and/or clinopyroxene are involved in the transformation. Thermodynamic modelling of local equilibria at dry conditions and with H2O in excess reveals that this stepwise transformation is caused by the varying reactivity of the local assemblages at the prevailing P-T conditions. Those reactions that result in the largest decrease of the Gibbs free energy from the dry case to the case with H2O in excess occur first. Once the reaction is facilitated, this effect is amplified because the density increase is largest at those grains boundaries that have reacted first, creating new fluid pathways through volume reduction. The calculated stable local mineral assemblages are consistent with those present in the sample indicating that element transport is limited, also supported by the observation that the fabric of the granulite is preserved in the eclogite. Our results demonstrate that reactive fluid flow is guided by the local energy budget along the grain boundaries, and that element transport during static re-equilibration is limited to the extent where it is thermodynamically advantageous.
The oceanic drivers of the 2017 Maud Rise Polynya
Authors: Narayanan Aditya , Gülk Birte , Roquet Fabien , Garabato Alberto
Published: March 2022

Maud Rise polynyas are rare events in the Weddell Sea (Atlantic sector of the Southern Ocean) that cause deep vertical mixing within the ocean column and large surface fluxes of heat with large impacts on  the local Weddell gyre circulation and on the Antarctic bottom water properties. Here we use a 1/12o ocean reanalysis product to assess the dominant drivers of ocean stratification leading up to the polynya event of 2016 and 2017 in Maud Rise, Weddell Sea. We carry out a potential vorticity (PV) budget to identify the dynamical components of the regional circulation responsible for changes in ocean stratification that culminated in the formation of the 2017 polynya. During 2015, an exceptionally strong (about 2x that of the previous three years) buoyancy-driven destratification led to a shoaling of the pycnocline, and the restratification at the end of 2015 remained weak. During 2016 and 2017, the buoyancy-driven destratification decreased in strength, becoming weakest during the polynya of 2017. The destratification was once again strong in 2018, but this was balanced by a stratifying forcing from the surface stress and advective components, the latter of which was associated with a transport of denser (more saline and cooler) subsurface waters from the flanks of Maud Rise. These denser subsurface waters maintained a strong stratification through 2018. These results show how interannual anomalies in local sea ice production and regional circulation can promote or inhibit the formation of polynyas in the region. Furthermore, it suggests that the Maud Rise polynya opened in 2017 following a chain of perturbations that started at least back in 2015, contrary to the common view that the polynya was initiated solely  by a series of short-lived storms in 2017.
The dependence of the climate simulated in a global storm-resolving model on its vertical resolution
Authors: Schmidt Hauke , Rast Sebastian
Published: March 2022

In global atmospheric modeling the importance of an appropriate ratio of vertical to horizontal model resolution has been emphasized earlier. Theoretical considerations for appropriate ratios have been based, e.g., on quasi-geostrophic considerations for large-scale flows and the dissipation conditions for gravity waves. In limited-area convection-permitting simulations it has been shown that in particular the simulation of shallow cloud layers depends on the vertical model resolution. 
A recent focus in global climate modeling is to increase horizontal resolutions down to a few kilometers grid spacing in order to resolve processes like convection that need to be parameterized at coarser resolutions. In these simulations, often the vertical model resolutions haven’t been changed much in comparison to traditional approaches. Questions like the following may arise: Is this appropriate? How strongly does the climate at storm-resolving horizontal scales depend on vertical resolution? Can convergence of the simulated climate be expected at a certain vertical resolution? Is it useful to invest in further increases of horizontal resolution without a refinement of the vertical grid?
To start answering these questions we have performed simulations with the ICON global atmospheric model at a horizontal resolution of 5 km with three different vertical grids comprising 55, 110, and 190 layers and corresponding vertical resolution in the troposphere of 400, 200, and 100 m, respectively, for a period of 6 weeks.  Here we will show the dependence of selected climate parameters, including the global energy budget, on the vertical resolution. 
High-resolution mineral dust modeling
Authors: Klose Martina , Unser Tabea , Basart Sara , Jorba Oriol , Benincasa Francesco , Pantillon Florian , Knippertz Peter , Pérez García-Pando Carlos
Published: March 2022

Dust emissions are linked with wind forces through a non-linear relationship. As a result, small errors in modelled wind speed lead to large errors in modelled dust emission. Dust models usually show satisfactory behaviour when dust outbreaks are caused by synoptic-scale weather systems. In contrast, smaller-scale dust events, e.g. haboobs or dust devils, are often unresolved at typical model resolutions and are hence unrepresented, in particular in coarse-grid global models. Haboobs are among the most important meteorological dust injection processes in the Sahara and Sahel in summer, both in terms of cumulative duration and intensity. The lack of haboobs or other unrepresented dust events likely leads to biases in the amount, spatial distribution, and seasonal variability of global dust emission and loading.

Here we present results of a high-resolution (~ 3 km), convection-permitting simulation for the year 2012 over northern Africa and the Middle East with the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model (MONARCH). In contrast to previous studies, our simulations do not only contain meteorological variables at high resolution, but also include a full representation of the dust cycle. We assess the impact of resolution on the spatiotemporal dust patterns compared to observations and model simulations at coarser resolution. We also identify haboobs in the high-resolution simulation and assess their properties, such as occurrence frequency, duration, size/intensity, to investigate how realistically they are represented. 
Role of Indian Ocean heating anomalies in the early winter ENSO teleconnection to the South Asian and North Atlantic regions
Authors: Kucharski Fred , Abid Muhammad  Adnan , Joshi Manish K. , Ashfaq Moetasim , Evans Katherine J.
Published: March 2022

The role of the Indian Ocean heating anomalies in the ENSO teleconnection to South Asia and North Atlantic/European regions are investigated in the early winter season. Using re-analysis data, CMIP5 simulations and idealized numerical model experiments it is shown that the ENSO teleconnections in early winter in these regions are dominated by an ENSO-induced heating dipole in the Indian Ocean region. The Indian Ocean heating dipole leads to a Gill-type response in the South Asian region through Sverdrup balance. For a warm ENSO event, this response is a cyclonic upper-level anomaly that shifts the subtropical South Asian jet southward and increases precipitation in the that region. The cyclonic anomaly is the starting point of a stationary Rossby wavetrain that traverses the North Pacific and North American region and eventually reaches the North Atlantic. Here transient eddy feedbacks are likely to strengthen a response that spatially projects on the positive phase of the NAO and negative phase of the Atlantic ridge patterns. For cold ENSO events these anomalies are roughly opposite. The importance of the Indian Ocean heating dipole decreases towards late Winter due to a southward shift of the Indian Ocean rainfall climatology and a more dominant direct wavetrain from the central Pacific region.
New analyses of the stress ratio and stress regime in the Earth’s lithosphere from numerical simulation models of global mantle convection
Authors: Yoshida Masaki
Published: March 2022

A series of numerical simulations of mantle convection in 3D spherical-shell geometry were performed to evaluate the intraplate stress regime from numerically obtained velocity and stress fields. The intraplate stress regime was quantitatively classified into nine types by analyzing the principal deviatoric stress axes and the “stress ratio,” which is a continuous parameter accounting for the stress regimes. From the viewpoint of global geodynamics, this study analyzed the depth profile of the stress ratio across the entire depth of the mantle. The results demonstrated that the radial viscosity structure of the mantle interior strongly affected intraplate stress regimes, and the combination of increased viscosity in the lower mantle and the low-viscosity asthenosphere enhanced the pure strike-slip faulting regime within moving plates as indicated using visco-plastic rheology. The temporally averaged toroidal-poloidal ratio (T/P ratio) at the top surface of mantle convection with surface plate-like motion and the mantle’s viscosity stratification may be comparable to the observed T/P ratio of present-day and past Earth. The normal faulting (or strike-slip) regime with a strike-slip (or normal faulting) component, as well as the pure strike-slip faulting regime, were broadly found in the stable parts of the plate interiors. However, the significant dominance of these stress regimes was not observed in the depth profile of the toroidal-poloidal ratio as a remarkable peak magnitude near the top surface of the lithosphere. This result implies that the strike-slip component analyzed in this study does not directly relate to the formation of strike-slip faults that are infinitely narrow plate boundaries compared with the finite low-viscosity boundary obtained from a mantle convection model with visco-plastic rheology. Nonetheless, this first analysis of the stress ratio may contribute to an improved understanding of the intraplate stress reproduced by future numerical studies of mantle convection with further realistic conditions.
Short vs. long amosite fibers: implication of particle clearance for asbestos-associated pulmonary inflammation and fibrosis
Authors: Leinardi Riccardo , Lescoat Alain , Yakoub Yousof , Pochet Amandine , Turci Francesco , Huaux François , Lecureur-Rolland Valérie
Published: March 2022

Exposure to asbestos is known for inducing inflammation, pulmonary fibrosis, lung cancer and malignant mesothelioma. Although several novel biomarkers and treatments are being tested, these chronic disorders are currently incurable, and the prognosis is particularly poor. The development of asbestos-induced cancer results from mutations, cell transformation and proliferation caused by reactive oxygen species and elevated levels of pro-inflammatory cytokines. Fiber-induced chronic inflammation also explains asbestosis, an interstitial lung disease characterized by uncontrolled matrix protein deposition leading to detrimental lung fibrosis. The investigation of the in-vivo molecular mechanisms driving asbestos pathogenicity is still a matter of debate. In this context, it is accepted that the physico-chemical properties of the fibers play a crucial role in causing adverse effects, and long fibers are still considered more toxic than short ones. Indeed, when fibers reach the alveolar space and migrate to the pleural/peritoneal cavity, long and thin fibers shows stronger inflammogenic, fibrogenic and tumorigenic effects than short fibers, in the long term. It is largely hold that short asbestos fibers are more easily cleared from the lungs and elicit a lower reactional and/or inflammatory effect. To further investigate this paradigm of toxicity, we compared the pro-inflammatory and pro-fibrogenic potential of short and long amosite fibers in in-vitro (J774 murine macrophages) and in-vivo (C57BL/6 mice) models. Surprisingly, our results demonstrated that short fibers were more prone to induce in-vitro cytotoxicity, accompanied by the release of pro-inflammatory biomarkers, in comparison to long fibers. On the contrary, the long fibers were significantly more inflammogenic and fibrogenic in the lungs of treated mice, while the short fibers were almost inert and did not induce acute and chronic inflammation and fibrosis. Furthermore, we observed that, while the long fibers were still present in the lungs of the animals 4 months after the exposure, the short amosite was substantially absent. These findings imply that the pulmonary deposition and a defect of clearance of the fibers play a crucial role in the development of in-vivo detrimental effects associated to long asbestos. This effect overcomes the mere in-vitro cytotoxic and inflammogenic potential of short fibers. Present results provide new insights into the mechanisms that drive asbestos toxicity, opening new perspectives for the development of reliable in vitro tests that fully predict health adverse effects associated to inorganic mineral fibers.
Mechanisms and drivers of the 2021 Pacific Northwest heatwave
Authors: Schumacher Dominik L. , Hauser Mathias , Seneviratne Sonia I.
Published: March 2022

The Pacific Northwest is characterized by a temperate climate with mild to warm summers, yet in late June 2021, the region was ravaged by extreme heat and ensuing wildfires. With local daily maximum temperatures 20 °C above the long term mean, the occurrence of such a brute heatwave makes it imperative to understand the underlying physical processes. Using the Community Earth System Model, we simulate this exceptional event and disentangle its thermodynamic and dynamic drivers. A factorial experimental design based on the ExtremeX framework is employed, in which the mid and upper-tropospheric circulation and soil moisture are either prescribed using reanalysis (ERA5) data, or calculated interactively. With this setup, the lower troposphere can always respond to land and ocean surface fluxes. Our results indicate that, despite widespread drought conditions in the analysis region (including the metropolitan areas of Portland, Seattle and Vancouver) and surroundings, the dynamic contribution far exceeded the effect of anomalous soil moisture. We further disentangle the soil moisture contribution into initial and event-driven, and find that precipitation in the first half of June 2021 prevented even higher near-surface temperatures by weakening the initial effect. Overall, the analysis highlights the role of the anticyclone that governed the large-scale circulation, and whose intensity during summertime and within 45°N–60 °N surpasses any other event in recent decades. As such, this heatwave presents an opportunity to investigate whether our Earth System Model of choice is capable of generating similarly extreme heat at large spatial scales on its own, i.e. with fully interactive winds. While the mean intensity of hot anticyclonic summer events over land (45°N–60 °N) is underestimated with respect to our reference simulation with prescribed circulation, the model portrays stronger variability with an interactive atmosphere and hence generates heatwaves that rival and even surpass the large-scale temperature anomalies of the Pacific Northwest 2021 event. Our investigation also points to strong temperature anomalies aloft, which we track back in time with a Lagrangian trajectory model driven by ERA5 data. By doing so, we find evidence for intense latent heating of the air that would later be part of the anticyclone, and mixed into the unusually deep atmospheric boundary layer. We further demonstrate that in the absence of anthropogenic climate change, an otherwise identical heatwave would not have reached such extreme temperatures. Altogether, this study shows that for the right atmospheric configuration and fuelled by our changing climate, unprecedented heat may be unleashed even in regions traditionally considered devoid of excessive heatwaves.
Simulating economic impacts of droughts on German agriculture using the country-scale Multi-Agent System model DroughtMAS
Authors: Nagpal Mansi , Heilemann Jasmin , Klassert Christian , Peichl Michael , Klauer Bernd , Gawel Erik
Published: March 2022

Given widespread and serious implications of increasingly intense and frequent extreme events such as droughts and heat waves, there is a growing demand for integrated approaches capable of supporting prospective risk reduction through better adaption to a changing climate. While anticipating future impacts is essential to inform policy decisions, there is simultaneous need for projections at higher spatial resolution to forecast the local effects of global change. Here, we present a spatial multi-agent system (MAS) model, DroughtMAS, calibrated using a positive mathematical programming (PMP) approach. The model simulates land-use adaptation to future drought conditions, estimates the economic damages of future droughts, and assesses policy measures aimed at enhancing the drought resilience of German agriculture. It represents the biophysical and agro-economic heterogeneity of German agriculture through 23,396 individually parameterized land-user agents located on a country-wide 4x4km grid. Cropping behavior is calibrated with land-use data from high-resolution remote sensing analyses and public records and validated with independent land-use data. The economic parameters ground the model to a policy-relevant context while the statistical yield functions capture the impacts of biophysical factors on crop production. These yield functions enable the model to respond to soil moisture changes from observed data or projections from hydrological models. DroughtMAS extends the classical PMP model to capture short-run responses to droughts more realistically and analyze how fast the farmers move towards the desirable equilibrium conditions under recurring droughts. The model shows that farmers gradually adapt to prolonged drought conditions, with a lower degree of adaptation in the first drought years only slightly mitigating drought impacts. We present first analysis of future drought scenarios to demonstrate the ability of the model to quantify risks from potential droughts across Germany in monetary terms. The results provide bottom-up estimates of economic damages of droughts accounting for much needed short-run behavioral dynamics of adaptation. This provides valuable and realistic projections of future drought impacts of farm-specific changes aggregated at national scale. The model also presents spatiotemporal pattern of these impacts, showing the potential for such projections to inform targeted policy interventions. DroughtMAS provides a platform that can be extended to capture additional adaptation behaviors (e.g. drought-resilient crops, adapted crop calendars, irrigation systems) and combined with other models that require empirically validated inputs about various agricultural decision-making conditions.
The safety paradox in flood protection: the importance of communicating and contextualizing uncertainties
Authors: Höllermann Britta , Evers Mariele , Johann Georg
Published: March 2022

The flood events of 13-15 July 2021 in Germany brought the relevance of flood prevention acutely and once again to our attention. As the earth's atmosphere heats up, nature has more and more intense events in store for us, which push our flood protection and management measures to their limits and beyond. For planning purposes, but also in case of an event, it is therefore highly relevant to improve the communication of uncertainties and the assessment of their potential impact, e.g. in the climate or flood forecast, in a target group-oriented manner.

In Germany and in the European Union, the conditions for flood risk management have been improved since 2007 with the implementation of the European Flood Risk Management Directive (FRMD) and the amendments to the Federal Water Act. Many new instruments such as flood hazard and risk maps, building regulations or the category of flood emergence areas were introduced. For example, flood hazard and flood risk maps and corresponding management plans have been prepared on the basis of historical discharge data, water levels and hydrological and hydraulic modelling. However, recent examples have shown that the objective of the FRMD to reduce flood-related risks to human health, the environment, infrastructure and property has only been achieved to a limited extent.

In this paper we discuss why the developed maps and plans do not lead to a sufficient risk perception and why, in case of a flood event, it is often not clear what actions need to be taken when and by whom. For this, we want to highlight three aspects in particular:

1) Data: importance of using measured data and dealing with historical flood events, which are only comparable to a limited extent to today's and future conditions, which are shaped by the influences of climate change.

2) Actors: importance of involving different actors in the flood risk management planning process to strengthen risk perception and responsibility.

3) Communication: Importance of communicating uncertainties target group-specific and visualising uncertainties and their possible impacts context-specific.

For effective and sustainable flood risk management, we therefore believe that we are in need of a communication and dissemination strategy in order to contribute to a transparent description of the roles of the actors and their responsibilities. Consequently, the already developed tools (e.g. flood hazard /risk maps) should be supplemented by involving regional actors, uncertainty information and its effects should be classified and communicated to all decision-making levels in a way that is appropriate for the target group.
Enrichment of immobile elements in synmagmatic fractures
Authors: Witcher Taylor , Burchardt Steffi , Heap Michael , Kushnir Alexandra , Pluymakers Anne , Schmiedel Tobias , Pitcairn Iain , Mattsson Tobias , Kaskes Pim , Claeys Philippe , Barker Shaun , Lissenberg Johan
Published: March 2022

Useful minerals containing rare Earth elements (REE) and metals are sourced from magma bodies, but exactly how these elements initially leave the magma is not well known. Here we present textural and chemical analyses of mineral-filled fracture bands within the rhyolitic Sandfell laccolith exposed in eastern Iceland. The fracture fillings showcase dynamic and complex textures and imply multiple energy levels during precipitation. The dominant mineral phases are Fe- and Mg-oxides, Mn carbonate, and La/Ce oxide. The textures they present are comb, laminate, radial, and a rounded reworked clastic texture filling the tips. Microtomography images of hand-samples show the fractures are stretched-penny shaped, and contain 80 vol% fillings and 20 vol% void space. The connectivity of fractures within one band is limited to 1-3 neighbours, via small oblique fractures joining two main fractures together. µXRF measurements revealed distinct halos of 0.8 wt% Fe depletion surrounding each facture, and within the fracture-fill a strong enrichment in an unusual suite of elements including Fe, Mn, Cl, Zn, Cr, Y, Ce, and La. This assemblage is puzzling, as many of these elements are typically carried by fluids which have strong alteration effects on the surrounding rock, and there is a lack of this kind of alteration at Sandfell. Our working hypothesis is that the formation of the fractures provided a degassing pathway through the impermeable magma. However, the nature and the composition of the magmatic volatiles are as yet unknown. The minimal connectivity between fractures (at hand-sample scale) suggests fluid would have travelled through the length of one to three fractures until intersecting with another fracture band system, and minerals precipitated along the way. Given the ubiquitous occurrence of the fracture bands within the laccolith, this small-scale process compounds into large amounts of mass transfer overall. The fractures at Sandfell may be a snapshot of the initial process of removing incompatible elements from silicic magma.
Geomagnetic Observatory at Lampedusa Island: Characterization of local magnetic activity and comparison with the other Italian observatories
Authors: Di Mauro Domenico , Regi Mauro , Lepidi Stefania , Del Corpo Alfredo , Dominici Guido , Bagiacchi Paolo , Benedetti Giovanni , Cafarella Lili
Published: March 2022

At present, the geomagnetic observatory at Lampedusa (south of Sicily — Italy, geographic coordinates 35°31′N; 12°32′E, altitude 33 m a.s.l. - provisional IAGA code: LMP) is the southernmost point of observation in European territory, and since 2007 it contributes at filling the spatial observational gap in the whole south Mediterranean and North African areas. A signature of very low electromagnetic noise is expected at LMP, since it is located in the inner part of a wild park with limited access, far away from the urbanized areas of the island. LMP lies in the middle of the Mediterranean Sea, while the other two Italian observatories (Castello Tesino – CTS and Duronia - DUR, in North and central Italy, respectively) are located in the continental territory.

Comparisons among the three observatories, in both time and frequency domains, allow to magnetically characterize the Italian territory. Both 1-minute and 1-second data for the years 2017-2020 are analyzed under a statistical approach and also single event analysis is performed. Superposed Epoch Analysis (SEA) of geomagnetic data from the three observatories returns individual responses to external triggers during geomagnetic storms as well as SSC and SI events, indicating that in correspondence to impulsive inputs a peculiar feature arises at LMP, probably as contribution of electric currents in the surrounding sea salt water. Magnetic responses in the Ultra-Low-Frequency (ULF, 1 mHz–5 Hz) range from spectral, local Signal-to-Noise Ratio (SNR) analyses under different local time are computed, showing that the signal emerges mainly during morning hours, as expected for upstream waves related ULF source waves: in particular, the distinct narrow band characteristic of SNR at LMP indicates that the ULF signals are here mainly uncontaminated by local Field Line Resonance (FLR) as at DUR and CTS, while lower noise levels estimated at LMP suggest a smaller anthropogenic contamination in this frequency range. Moreover, for the first time at such low latitudes in the Mediterranean region, we find evidence of FLR events on Duronia–Lampedusa intermediate field line with the application of the gradient method, a consolidated technique that provides estimates of the ULF standing wave frequencies.. Results from data retrieved by geomagnetic observatories, whose long time series of data are of primary importance, demonstrate a unique contribution in characterizing the magnetospheric response to external events.
Mapping and analysing “badass gullies” in the loess regions of Lower Austria
Authors: Diem Sarah , Pöppl Ronald
Published: March 2022

Gully erosion represents a core process of land degradation and a serious threat to ecosystems and their services. Loess regions in the northern part of Lower Austria can be considered as particularly susceptible to the development of gullies. However, relatively little attention has been paid to gully erosion in these areas (e.g. neither gully inventories, nor information on gully characteristics are available). Therefore, the aim of this study was to map, document and geomorphometrically analyse gullies and to further delineate gully hot spot areas in the loess regions of Lower Austria.
A Digital Elevation Model (DEM) with a spatial resolution of 1 m has been used to visualise, map and geomorphometrically analyse gully erosion features in the research area in a GIS. Moreover, calculations of gully volumes have been adduced to determine the amount of eroded material in a selected gully hot spot catchment. The main focus throughout the study has been put on sunken lanes and permanent gullies, which have been explicitly identifiable in this region.
The results show strong concentrations of gullying in the loess areas of the eastern Waldviertel and the Weinviertel regions, both being characterised by intensive agricultural use. Sunken lanes are mainly found in the hilly and terraced landscapes of vineyards, while clusters of permanent gullies are usually found in agricultural fields but also forests surrounded by agriculture and used for silviculture. The hot spot areas exhibit a gully density of up to 17 permanent gullies per km² and 5 sunken lanes per km². Permanent gullies are often of remarkable size, showing volumes of up to 100,000 m³, more than 500 m in length and depths reaching 20 m and more. The longest observable sunken lane has a length of 1.6 km and a volume of nearly 70.000 m³.
More detailed results will be presented at the EGU General Assembly 2022.
Investigating the pore scale mechanism of miscible phases mixing in porous medium 2D
Authors: Eliyahu-Yakir Yahel , Ballas Tal , Abezgauz Ludmila , Edery Yaniv
Published: March 2022

Abstract

The process of a fluid replacing a separate miscible fluid in a porous medium is present in many industrial and natural systems, such as enhanced oil recovery, CO2 sequestration and salt-fresh water interfaces in the ground. While the replacement can be approximated with the Darcy law, the mechanisms of the miscible phases mixing to the displacement remain unclear, specifically as the heterogeneity of the domain increases. As this mixing influences the reaction pattern between the fluids, it is important to estimate it using indirect measurements that are available, such as pressure and flux measurements. We propose a set of experiments that allow us to observe and measure the displacement and mixing process in high resolution and with the use of image analysis we can distinguish between the mechanisms. We can clearly see how the heterogeneous rate of the pore structure influences the mixing pattern, rate, and duration. Surprisingly, we found a clear and typical “mark” of the mechanisms on the flow rate, under constant pressure, which allows us to relate the heterogeneity level of the structure to the ratio of displacement to mixing.
Automatic generation of the adjoint of the StagYY mantle convection model
Authors: Coltice Nicolas , Blessing Simon , Giering Ralf , Tackley Paul
Published: March 2022

Motions within the Earth mantle and tectonics constitute a single self-organized system which is cooling the planet over its geological history. Since the end of the XXth century, models of mantle convection self-generating plate tectonic behavior have progressed to a state that makes them applicable to global tectonic problems. The possibility of combining geological and geophysical data with dynamic models to retrieve the recent history of mantle flow and tectonics becomes realistic. Therefore, it is a challenge to build inverse methods to study inverse and sensitivity problems in the Earth's mantle convection. We have automatically generated the tangent-linear and the adjoint source code from the StaggYY code (Tackley, Phys. Earth Planet. Int. 171, 7-18, 2008). The Fortran code of the model was translated to the corresponding derivative codes using TAF (Transformation of Algorithms in Fortran), source-to-source translator. All codes run in parallel mode, using MPI (Message Passing Interface). The economic taping strategy of TAF, including re-computations, and checkpointing, helps to keep the memory footprint of the adjoint code low and the performance high. We highlight some key features of the automatic differentiation, evaluate the performance of the adjoint code, and show first results from 2D and 3D sensitivity fields, focusing on the relationships between temperature in the mantle and tectonics. Ultimately the addjoint code shall be applied to inversion and assimilation problems using a bayesian framework.
Investigation of Stibnite (Antimony) Scale in Germencik Geothermal Site, Büyük Menderes Graben, Western Turkey
Authors: Tonkul Serhat , Baba Alper , Demir Mustafa Muammer , Regenspurg Simona
Published: March 2022

Scale problems in geothermal power plants are one of the reasons that reduce power plant efficiency. Silica scaling, calcite scaling, and sulfide scaling are the most common scale types in geothermal power plants. These scale problems in geothermal power plants can be seen in geothermal wells and surface equipment systems. In this context, various measures should be taken to control the scale problems in geothermal power plants. In this study, the stibnite scaling observed in the preheater system of the Germencik geothermal power plant in the west of Turkey is discussed in full detail. Possible types of scale that may occur in the geothermal wells in the power plant were revealed, and the optimum reinjection temperature was determined for stibnite scaling, which reduces the efficiency of the power plant. Within the 3D modeling of the geothermal power plant and different geochemical models, the precautions to be taken at the power plant are examined in all details.

Keywords: Stibnite, Scaling, Binary power plants, Germencik, power plant efficiency

Acknowledgments: This study has received funding from the European Union’s Horizon 2020 research and innovation programme under agreement, REFLECT Project,  No: 850626.
Assessing the pressure (in)dependence of cross-property relations
Authors: Cilli Phillip , Chapman Mark
Published: March 2022

It is known that geological reservoir characterisation can be improved by the joint modelling and inversion of both electrical and elastic data, however the relationship between a rock’s electrical and elastic properties, which is intrinsic to these methods, is relatively uncertain. On top of this, estimating reservoir pressure from geophysical measurements is an essential part of the 3D and 4D monitoring of CO2 injection and hydrocarbon production, and while electrical and elastic properties are affected by pressure, the effect of pressure on electrical-elastic relations is less obvious.

Here we use the Cross-Property Differential Effective Medium approximation to model public-domain electrical-elastic laboratory measurements made on brine-saturated clean and mixed sandstones cores at 6 effective pressures ranging from 8 MPa to 60 MPa. Although the approximation is able to realise a large proportion of the electrical-elastic space bounded by the Hashin-Shtrikman bounds using a range of permissible parameter values, we find the model parameter, equivalent pore aspect ratio, varies very little as a function of pressure when modelling the measured data. Interestingly, we see equivalent pore aspect ratio changes exponentially as a function of pressure with an R2 value of over 0.99 when modelling clean sandstones, a trend which has been observed previously in single-property inclusion modelling. This small variance in the model parameter as a function of pressure corresponds to an observably small change in the samples’ electrical-elastic measurements with pressure.

We conclude the electrical-elastic properties of the examined clean and mixed brine-saturated sandstones are only weakly dependent on pressure and we demonstrate how a single, pressure-independent model parameter is able to model the electrical-elastic measurements of both the clean and mixed sandstones with reasonable accuracy over the full range of experimental pressures.