bluuebunny/crossref_metadata_2025 huggingface dataset:
Induced earthquakes at the carbon sequestration site Carbfix2, Hellisheiði, Iceland
Authors: Hjörleifsdóttir Vala , Gunnarsson Gunnar , Kristjánsdóttir Sigríður , Sigfússon Bergur , Geirsson Halldór , Jónsdóttir Kristín , Gunnarsson Ingvi , Ágústsson Kristján
Published: March 2020

The 303 MW Hellisheiði, Iceland geothermal power plant was commissioned in 2006 and in early September 2011, reinjection of geothermal fluid was initiated in the second reinjection site of the plant; Húsmúli.  The site has 5 injection wells in operation, with depths of over 2000 m and a total of up to 500 l/s of fluid being reinjected into the site.  Seismicity had previously been observed in the region, including both natural seismicity before power plant operations started (e.g. Foulger et al., 1988) and induced seismicity during drilling of the injection wells (Ágústsson et al., 2015).  The reinjection caused severely increased level of seismicity within days, with two earthquakes of M 4.0 and M3.9 respectively, occurring a little over a month after the start of reinjection (Icelandic Meteorological Office catalog). The injection was also accompanied by uplift of approximately 2 cm (Juncu et al., 2018).  Due to the increased level of seismicity, a committee was formed and several measures on how to control it were suggested – including starting reinjection gradually after it has been stopped (Bessason et al., 2012).

In 2014, as a part of the Carbfix2 project, the reinjection fluid in Húsmúli was combined with gas, and CO2 and H2S, previously being released into the atmosphere, is now captured and reinjected into the basaltic formation (Matter et al., 2016, Gunnarsson et al., 2018).  It is estimated that the CO2 and H2S are crystalized into calcite and pyrite in under 2 years (Gunnarsson et al., 2018). This project has been very successful and is currently capturing and permanently storing an estimated 33% of the CO2 and 75% of the H2S extracted.

In this study we analyze seismicity data as reported by the Icelandic Meteorological Office Regional network, (1991-present) and the ON Power/ISOR local network (2016-present) and compare with operational parameters.  We show 1) how the seismicity responds to changes in flow, pressure and temperature of the injected fluid, 2) how individual wells seem to respond differently, 3) how the mitigation measures taken by the operator have worked and 4) look for changes in seismicity due to the CO2 sequestration.

This work has been funded by the European Union’s Horizon 2020 research and innovation Program projects Carbfix2 (grant agreement number 764760) and S4CE (grant agreement number 764810).
Deformation Regimes in Cratons Caused by Gravitational Instabilities
Authors: Ballı Açelya , Göğüş Oğuz , Artemieva Irina , Thybo Hans
Published: March 2020

Most cratonic lithospheres are stable entities that have not been deformed since their formation in the Archean. In contrast, geological and geophysical inferences showed that North China and Wyoming Cratons have been deformed/destroyed under specific geodynamic circumstances (e.g metasomatization, slab dehydration). For instance, lithospheric roots are densified-destabilized and they may eventually sink into the mantle. Here, numerical experiments are used to investigate how high-density anomalies/eclogite in the lower crust that is varying in size, density and geometry may control the lithospheric removal process. Based on a large set of parametric numerical calculations, we first classified the lithospheric removal style (e.g localized, non-localized, high degree, and pierce through). In the case where the eclogite blocks attached to the lower crust, two different conditions develop; localized deformation and non-localized deformation occur due to the small-scale convection. Two new different removal mechanisms are evolved after the eclogite becomes detached from the lower crust; (i) pierce through mechanism subsequent to localized deformation and (ii) high-degree deformation following non-localized deformation. While the width of the eclogite block causes high-degree deformation, it is observed that with increasing thickness it leads to the formation of viscous drips. Experimental results indicate that eclogite block(s) under the cratons may still be there while creating small wavelength MOHO depth variations.
The ocean radiocarbon reservoir age over the last termination and the calendar age uncertainty of marine samples: a sensitivity study with a coupled climate model
Authors: Mouchet Anne , Mikolajewicz Uwe , Voelker Antje
Published: March 2020

Ocean circulation plays an essential role in Earth’s climate and the global carbon cycle. A prerequisite for improving confidence in future climate projections is the accurate numerical modeling of past deep ocean circulation changes. Unfortunately our understanding of such changes is impeded by ambiguities in the data-based reconstructions which heavily rely on radiocarbon dating of marine samples. Central to this method is the knowledge of the reservoir age (the age difference between the surface ocean and the atmosphere). Concomitant changes in atmospheric levels, air-sea exchange rates, and ocean circulation have the potential to drive large temporal and spatial changes of this reservoir age over the deglaciation. However these changes are not well constrained by field evidence. In consequence large uncertainties affect the dating of main climate events. Model studies allow complementing field data while also providing the means of assessing the sensitivity to different processes.

Here, we investigate the sensitivity of the radiocarbon reservoir ages and reconstructed calendar ages over the last termination. For this purpose we take advantage of a set of transient simulations performed with the Max Planck Institute Earth System Model (MPI-ESM) with interactive calculation of river runoff and automatic adjustment of model topography. The experiments, starting at 26 ka BP, are constrained with prescribed time varying ice sheets and topography in addition to variations of the Earth orbital parameters and reconstructed atmospheric greenhouse gases concentrations. Changes in ice sheet volume naturally result in freshwater surges which affect the global circulation and water masses distribution. Ocean radiocarbon is included in the model. The atmospheric 14C follows the INTCAL13 reconstruction while the impacts of varying wind speed, sea-ice cover, and atmospheric CO2 on air-sea exchange rates are explicitly included.

Different ice-sheets reconstructions (ICE-6G_C and GLAC-1D) and model configurations (addressing vertical mixing, bathymetry and land-sea mask) provide a range of ocean responses. The impact on reservoir ages of uncertainties related to planktonic foraminifer species-specific habitat is also considered. Together with the suite of model states this provides a range of reservoir ages over time. A calibration step allows then obtaining an estimate of the temporal evolution over the deglaciation of the time resolution of the radiocarbon dating method. Regional and global evolutions are examined and discussed.
Simulation of SOA formation in the Landes pine forest in south-western France, relative weight of initial ozone, NO3 and OH attack ?
Authors: Cholakian Arineh , Beekmann Matthias , Coll Isabelle , Flaud Pierre-Marie , Perraudin Emilie , Villenave Eric
Published: March 2020

Organic aerosol (OA) still remains one of the most difficult components of the aerosol to simulate, given the multitude of its formation precursors, the uncertainty of its formation pathways and the lack of measurements of its detailed composition. The LANDEX project (The LANDes Experiment), during its intensive field campaign in summer 2017, gives us the opportunity to compare a detailed list of measurements (VOC, NOx, radicals including NO3, aerosol components, …) obtained within and above the Landes forest canopy, to simulations performed with CHIMERE, a regional Chemistry-Transport Model. The Landes forest is situated in the south-western part of France, and is one of the largest anthropized forest in Europe (1 million ha), composed by a majority of maritime pine trees, strong terpene emitters, providing a large potential for biogenic SOA formation.

In order to simulate organic aerosol build-up in this area, the set-up of a specific model configuration, adapted to local peculiarities, was necessary. As the forest is inhomogeneous, with interstitial agricultural fields, high-resolution 1 km simulations over the forest area were performed, imbedded into a 5 km resolved French and a 25 km resolved European domains. BVOC emissions were predicted by MEGAN, but specific land cover needed to be used, chosen from the comparison of several high-resolution land-cover databases. Also, the tree species distribution needed updated for the specific conditions of the Landes forest. In order to understand the canopy effect in the forest, sensitivity tests were also performed and the diffusivity between the first two layers were changed. The impact of each of these refinements with respect to the standard model set-up on the concentration changes of biogenic VOCs and organic aerosol was calculated and compared to observations. In addition, the sensitivity of SOA build-up with respect to the organic aerosol scheme (standard scheme within CHIMERE, VBS schemes with updated yields for OA formation from BVOCs, …) was assessed.

The ensemble of simulations allowed tracing back the origin of BSOA build-up within and above the Landes forest canopy. Above the canopy, the major simulated pathway of SOA formation is monoterpene oxidation by NO3, while within the canopy, for sufficiently low mixing during nighttime, the NO3 radical is suppressed and only little contributes to SOA build-up. This is in accordance to observations and reactivity considerations which show that within the canopy, ozone attack on sesquiterpenes is the major nighttime SOA source.  
The role of obliquity forcing on the interglacial climate instabilities in the mid-latitudes of the North Atlantic
Authors: Rodrigues Teresa , Zeng Xu , Padilha Mária , Oliveira Dulce , O. Grimalt Joan , Abrantes Fátima
Published: March 2020

Anthropogenic CO2 release into the atmosphere leads to temperature projections for 2100 only experienced on Earth since many million years. However, those periods are poorly known due to low temporal and spatial data and ill-defined climate forcings. However past warm periods (interglacials), occurring during the Quaternary, under variable boundary conditions (e.g. greenhouse gases concentration, sea level and ice sheets size, insolation and orbital forcing), can provide invaluable information on the dynamics and processes behind natural warm climates. Here we present records for the sea surface temperature based in Uk’37-SST at orbital and millennial-scale over the last 1.25 Ma, with special focus on the past interglacials of two SW Iberian margin sedimentary sequences recovered during IODP Expedition 339,  Sites U1385 (37°34.285′N, 10°7.562′W;  2589m) and U1391 (37°21.5322′N, 9°24.6558′W; 991m). We also performed a data-model comparison to explore the dynamics related with the role of obliquity on the Atlantic Meridional Overturning Circulation (AMOC) changes. Our data  show that Interglacials are characterized by an interval of maximum warmth followed by a temperature decline punctuated by millennial-scale SST oscillations. In most cases the first stadial marks the beginning of a glacial inception that is characterized by an abrupt SST decrease, followed by high frequency SST oscillations, and large amounts of freshwater input. This suggests a climatic change from interglacial to glacial conditions linked to the start of ice sheets growth (enrichment of d18O) and the AMOC slowdown resulting in an enhanced cooling of the mid-latitudes.
Assessment of the mechanism of fracture propagation of soft rock coastal cliffs by using non-local constitutive models
Authors: Lollino Piernicola , Fazio Nunzio Luciano , Perrotti Michele , Genco Alessio , Elia Gaetano , Ciantia Matteo Oryem
Published: March 2020

The assessment of susceptibility to failure of soft rock coastal cliffs, along with the associated failure mechanism, is not a simple task. Equilibrium conditions depend on the combination of several factors such as structural setting, rock mechanical strength, weathering processes, the hydro-mechanical action of sea waves, the variation of the rock cliff geometry, to mention some of the most important ones. From a geomechanical perspective, the brittle - strain softening behaviour of the rocks plays a key role in the onset and propagation of failure (Ciantia & Castellanza 2015). In particular, the rapid strength reduction occurring after peak under mechanical loading leading to localised deformations within shear fractures is detrimental for rock cliffs. Taking rock brittleness into account in numerical simulations under the framework of continuum mechanics is not straightforward, due to the problems related to a strong dependence of the numerical results from the adopted mesh when strain-softening laws are implemented (Vermeer and Brinkgreve 1994). Nowadays, several regularization techniques are available to control the size of the localised region and prevent the mesh dependence. Within regularization techniques, the nonlocal integral type solution has the advantage of not changing the field equations which facilitates numerical implementation. In this approach, the chosen nonlocal variables are valuated from spatial averages of the field variables in a neighbourhood, and the constitutive model is updated by replacing a local variable with its nonlocal counterpart. Consequently, the constitutive response of a Gauss point is influenced by all the integration points within a neighbourhood, with the size determined through a characteristic length (Bažant and Jirásek 2002). This contribution addresses the problem of the stability of an ideal 2-D plane strain coastal cliff, 20-m high, by means of the use of a non-local constitutive model implemented in a commercial finite element code (Mánica et al. 2018). The numerical results show insights into the evolution of the strain field and the process of slip surface/fracture propagation in the rock cliff as well as highlight the importance of regularising the finite element solution in the presence of brittle materials.
Bayesian back analysis for dynamic CPTu strain-rate correction.
Authors: Collico Stefano , Stegmann Sylvia , Kopf Achim , Arroyo Marcos , Devincenzi Marcelo
Published: March 2020

Dynamic Cone Penetration test (CPTu) is a cost and time efficient way of collecting in situ geotechnical parameters (i.e. cone tip resistance, sleeve friction and total pore pressure) of near-surface marine sediments for submarine slope stability analysis. Conventional-established correlation for geotechnical parameters estimation from CPTu are built on static CPTu data, requiring correction of dynamic CPTu sounding records mainly due to strain-rate effects (i.e. increasing of soil resistance due to the increase of applied strain-rate). Empirical correlations have been proposed to overcome this issue, nevertheless, their application requires the quantification of correlation’s coefficients for which no general regression has been derived yet, arising strong uncertainty in data conversion and consequently geotechnical parameter prediction. Moreover, dynamic CPTu parameters are also uncertain due to their inherent variability and instrument precision. In this framework, this study proposes a multivariable Bayesian back-analysis for probabilistic conversion of dynamic CPTu parameters into static CPTu profile. Inherent variability of soil properties, instrument measurements error and uncertainty introduced by correlations used are modeled as random variables and updated within a Bayesian framework. Equivalent samples are randomly generated from established proposal distributions and integrated with parameter’s prior knowledge through a hybrid Markov-chain MonteCarlo procedure. The proposed approach is tested for 20 dynamic CPTu tests, characterized by different impact velocities, performed at Trondheim Fjord. The method applied aims to provide an improvement of strain rate correction with respect traditional data conversion. Preliminary results well match with ones computed from back-calculation employing both static and dynamic CPTu profiles. Results should be further validated for mechanical soil delineation and geotechnical parameters prediction from CPTu.
Global wave height trends and variability from new multi-mission satellite altimeter products, reanalyses and wave buoys
Authors: Gommenginger Christine , Timmermans Ben , Dodet Guillaume , Bidlot Jean-Raymond
Published: March 2020

Accurate knowledge and understanding of the sea state and its variability is crucial to numerous oceanic and coastal engineering applications, but also to climate change and related impacts including coastal inundation from extreme weather and ice-shelf break-up. The increasing duration of the satellite altimeter record for sea state motivates a range of global analyses, including the examination of changes in ocean climate. For ocean surface waves in particular, the recent development and release of new products providing observations of altimeter-derived significant wave height make long term analyses fairly straightforward.

In this study, significant wave height climatologies and trends over 1992-2017 are intercompared in four recent high-quality global datasets using a consistent methodology. In particular, we make use of products presented by Ribal et al. (2019), and the recently released product developed through the European Space Agency Climate Change Initiative (CCI) for Sea State (Dodet et al. 2020, ESSD, in review). Regional differences in mean climatology are identified and linked to low and high sea states, while temporal trends from the altimetry products, and two reanalysis and hindcast datasets, show general similarity in spatial variation and magnitude but with major differences in equatorial regions and the Indian Ocean. Discrepancies between altimetry products likely arise from differences in calibration and quality control. However, multidecadal observations at buoy stations also highlight issues with wave buoy data, raising questions about their unqualified use, and more fundamentally about uncertainty in all sea state products. We discuss these results in the context of both the current state of knowledge of the changing wave climate, and the on-going development of CCI Sea State altimetry products.
‘Internet of Things’ for environmental sciences and education
Authors: Becker Rolf
Published: March 2020

The collective term ‘Internet of Things’ (IoT) encompasses a variety of technologies and methods providing novel opportunities for data acquisition and control in environmental sciences. Availability of cost effective components as well as support of large open source communities allow scientists to gain more flexibility and control over their experimental setups. However quality of measurements, stability of instruments as well as real costs for development and maintenance are often underestimated challenges. The presentation introduces current best practices of IoT principles in scientific applications. Examples of low cost sensors, low power electronics, wireless data transmission protocols, time series databases as well as real-time visualization are presented and discussed. Furthermore light is shed on non-technological issues of the ‘do-it-yourself’ or ‘maker’ approach such as social and psychological aspects. The ‘make-share-learn’ paradigm of the maker culture can be utilized to raise awareness. It provides significant opportunities for environmental education and community building which constantly gain more importance in the context of climate and environmental change.
Remediation of Kola Subarctic heavy metal contaminated soils via carbon pool regulation: link between structural characteristics of organic treatments with potential influence on soil properties and living organisms
Authors: Tregubova Polina , Koptsik Galina , Zherebker Alexander , Stepanov Andrey
Published: March 2020

In short-term incubation experiment (90 days with additional preincubation) in conditions, simulating summer season in Kola Peninsula, Russia, we implemented different organic amendments — humic subtances, peat-gel, biochar — for remediation of highly contaminated soils of technogenic barrens, situated in 2 and 5 km from active nickel processing industry. Unamended soils used in experiment are characterised by ablation of upper fertile soil layer, high acidity, high content of Ni, Cu, Fe, Zn, depletion of nutrients and organic matter, and, as consequence, by the absence of natural vegetation. To predict potential influence of amendments on contaminated soils and their capacity to immobilise HM bioavailable forms and improve soil health we provide data of structural characteristics with and without additional preparations evaluated by Fourier-transformed infrared (FTIR) spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Our data support the idea of high importance of organic amendment structural characteristics and link these characteristics with observed soil physical, chemical and ecotoxicological properties.

This study was funded by Russian Foundation for Basic Research according to research project No. 18-04-01028, high-resolution mass spectrometry was supported by Russian Science Foundation grant No. 19-75-00092.
The European wind from observational and simulated databases
Authors: García-Bustamante Elena , Navarro Jorge , González-Rouco Jesús Fidel , Lucio- Eceiza E. Etor , Rojas-Labanda Cristina , Palomares Ana
Published: March 2020

The New European Wind Atlas (https://map.neweuropeanwindatlas.eu) is developed based on the simulated wind field over Europe from a mesoscale model coupled to a microscale component through a statistical downscaling approach. The simulation that provides mesoscale inputs within the model chain has been decided upon a careful sensitivity analysis of potential model configurations. In order to accomplish model resolutions of 3 km over Europe, the broader European domain is partitioned into a set of 10 partially overlapping tiles. The wind field is simulated with the WRF model over these tiles and finally blended into a single domain. The wind outputs from a reference simulation is evaluated on the basis of its comparison with an observational database specifically compiled and quality controlled for the purpose of validating the wind atlas over the complete European domain. The observational database includes surface wind observations at ca. 4000 sites as well as 16 masts datasets. The observational dataset of surface wind (WISED) is informative about the spatial and temporal variability of the wind climatology, punctuated with singular masts that provide information of wind velocities at height. The validation of the mesoscale simulation aims at investigating the ability of the high-resolution simulation to reproduce the observed intra-annual variability of daily wind within the entire domain.

Observed and simulated winds are higher at the British, North Sea and Baltic shores and lowlands. Correlations are typically over 0.8. Surface wind variability tends to be overestimated in the northern coasts and underestimated elsewhere and inland. Mast wind variability tends to be overestimated except for some southern sites. Seasonal differences seem minor in these respects. Biases and RMSE can help identifying if systematic errors in specific tiles take place.

Therefore, performing model simulations of a high horizontal resolution over the broader European domain is possible. We can learn about the variability of surface and height wind both from observations and model simulations. Model observations are not perfect, but observations also present uncertainties. Good quality wind data, both at the surface and in masts are a requisite for robust evaluation of models. European wide features of wind variability can be recognized both in observations and simulations.
Underwater light field changes in Pärnu Bay influenced by weather phenomena and captured by Sentinel-3
Authors: Uudeberg Kristi , Randla Mirjam , Arikas Age , Soomets Tuuli , Toming Kaire , Reinart Anu
Published: March 2020

Climate change is expected to continue in the 21st century, but the magnitude of change depends on future actions. In the Baltic Sea, specifically in the Pärnu Bay region, this is predicted to mean warmer temperatures, less ice cover, more precipitations and a slight increase in average wind speed, furthermore extreme climatic events such as heavy rains, strong winds and storms will be more intense and frequent. The coastal waters play a central role in humans and nature's everyday lives as providing food, living and recreational opportunities. Since Pärnu Bay is one of the most eutrophied area in the Baltic Sea and provides living hood more the 800 fishermen, then regular monitoring is strongly recommended, but with traditional methods often unfeasible. The availability of free Sentinel satellites data with good spectral, spatial and temporal resolution has generated wide interest in how to use remote sensing capabilities to monitor coastal waters water quality, which affects the underwater light field and can lead even to changes in fish composition. However, these waters are optically complex and influenced independently by coloured dissolved organic matter, phytoplankton and an amount of suspended sediments. Therefore, the remote sensing of optically complex waters is more challenging, and standard remote sensing products often fail. In this study, we use satellite Sentinel-3 data to investigate weather phenomena as strong wind and precipitations effect to Pärnu Bay water quality parameters. We study the spatial and temporal scope of change of water quality parameters after the event. For that, we use optical water type classification based chlorophyll-a, suspended sediments and coloured dissolved organic matter algorithms on Sentinel-3 images and estimate underwater light field changes. Furthermore, we also use in situ data to analyses the frequency and the strength of weather events. Finally, we look at the composition of fish based on literature and we investigate the possible effects of the change of the underwater light field on fish composition.
An enhanced river routing scheme for the closure of global water budget
Authors: Materia Stefano , Peano Daniele , Benassi Marianna , Lovato Tomas , Gualdi Silvio , Cherchi Annalisa , Alessandri Andrea , Navarra Antonio
Published: March 2020

Large-scale river routing schemes are essential to close the hydrological cycle in fully coupled Earth System Models (ESMs). The availability of a realistic water flow is a powerful instrument to evaluate modeled land surface, a crucial component of the global climate whose properties are often simplified by heavy parameterization, due to lack of process knowledge and validation data. We built up a new concept of river routing model, named HYDROS (HYdro-Dynamic ROuting Scheme), that replaces the present scheme embedded in the CMCC-CM2 global coupled model. The new scheme aims at overcoming one of the current major limitations, that is the use of time-independent flow velocities parameterized as a function of topography. Through the imposition of hydraulic equations, HYDROS defines a time-varying flow velocity associated with the amount of lateral runoff generated by the ESM's land component and the flow through the river system. Compared to the scheme currently in place, HYDROS show improvements in the simulation of mean annual discharge phase, especially for the Arctic rivers and the Amazon. In the Mississippi case, an extreme flood episode is better caught by the new representation, indicating that the improved flow velocity better catches the discharge peaks after extreme rainfalls. The new routing model is not able to improve the volumes of simulated river discharge, whose magnitude depends on the ability of the ESM land surface scheme to generate correct surface and sub-surface runoff. Once implemented in coupled mode, HYDROS will guarantee a plausible amount and timing of freshwater discharge into the global ocean, unveiling possible unresolved feedback mechanisms occurring in proximity of river mouths.
Evaluating the role of biomass in the sorption of four UV-Filters
Authors: Sanchez-Vila Xavier , Rodriguez-Escales Paula
Published: March 2020

The presence of ultraviolet filters (UV) in personal and care products, like cosmetics or sunscreens, is quite common. Consequently, they have been found most of water systems (e.g. ocean, river, aquifers). In porous media, the two main processes governing their fate are sorption and degradation. In the case of degradation, it is mainly governed by co-metabolism processes, which means that these molecules are broken due to the presence of more labile organic carbon which facilitate an enzymatic activity in the system. On the other hand, most of UVs are characterized by high . Thus, sorption plays a central role in their fate. In dynamic biological systems, like hyporheic zones, bioremediation sites or Managed Aquifer Recharge facilities, a high amount of microorganisms, forming biofilms, can be found. In this work, we have evaluated the role of biomass as a sorbent of UV-filters. Furthermore, we have also evaluated the importance of redox conditions in the co-metabolic degradation, and thus, the production of biomass. To achieve this general objective, a conceptual and a numerical model were developed. The results of the models were compared with previous published data by Liu et al. (2013), which performed a set of batch experiments to evaluate the fate of UV under different redox conditions. The compounds evaluated were common UV filters: Benzophenone-3, the benzotriazoles (UV-326 and UV-329)), octyl 4-methoxycinnamatte and octocrylene.
Geomorphic processes and the stability of surfaces in the central Atacama Desert (Chile) – comparing Sentinel-1 InSAR coherence time series and field evidence
Authors: May Simon Matthias , Hoffmeister Dirk , Ullmann Tobias , Bubenzer Olaf
Published: March 2020

Recent analysis of spatio-temporal variations of Sentinel-1 InSAR coherences for the entire Atacama Desert have revealed that about 70% of the area show hardly any detectable surface change in an ENSO-affected time series between 2015 and 2018. This validates that geomorphic processes in the central Atacama are of remarkable slowness or even stagnant, as also suggested by the age of surfaces and landforms, i.e. the age of the landscape in general. Most of these surfaces in the central desert are characterized by rather smooth morphologies, which is a result of thick atmospherically derived salt and dust deposits masking the desert surface, supported by the presence of gypsum crusts and/or Biological Soil Crusts (BSCs). In contrast, geomorphic activity on recent time scales is typically linked to episodic Andean discharge or severe precipitation events, which can cause overland flow or flash flood activity even in the hyperarid core of the Atacama as recently shown by the 2015 rainfall event. Likewise, fog-related atmospheric moisture is assumed to provoke salt-driven shrink-swell processes, and episodic activity by slumping and/or seismicity may successively alter landforms in the central desert over longer time scales as well.

Based on Sentinel-1 InSAR coherence data, this contribution presents the spatial pattern of morphodynamic activity in the central Atacama Desert, which is paired with further independent variables achieved by remote sensing such as soil surface indices and geomorphometric parameters (e.g., using TanDEM-X WorldDEMTM, DLR science grant), ultimately characterising the different types of desert surfaces. The satellite-based regional morphodynamic pattern is compared to on-site field evidence collected between 2016 and 2019, which suggests (limited) geomorphic activity rather than stability on late Pleistocene time scales at a variety of locations. Among these locations are flood-affected channel systems and alluvial fans, but also patterned ground structures, zebra stripes, slump- or creep-related slope deposits, or BSC-covered surfaces, which are assumed to support aeolian deposition. Except for the flooding activity, field sites with inferred late Pleistocene to Holocene activity seem to be located in the fog-affected zones of the Coastal Cordillera. Our study shows that the combination of field and remote sensing data may contribute to a better understanding of past and present – particularly rainfall-independent – geomorphic processes in the hyperarid Atacama.
Hail climatology and impacts for the Netherlands
Authors: de Moel Hans , Wouters Lucas , Boon Maaike , van Putten Demi , Van 't Veen Bram , Koks Elco
Published: March 2020

Convective storms that produce large hail are among the most damaging natural hazards and globally losses due to these events are increasing. To evaluate and quantify the potential risk associated with these storms, hail climatologies are created from historical records. Unfortunately, a comprehensive analysis of the Netherlands does not exist.

The aim of this study is to create a hail climatology of the Netherlands and report on spatial and temporal hail risk by combining two approaches. The first approach relies on written documents containing information on historic events collected from Weerspiegel-magazine and the European Severe Weather Database (ESWD), from the time period 1974-2019. The second approach utilizes radar-data from the time period 2008-2019 and implements a radar-based Hail Detection Algorithm (HDA) to estimate hailstone sizes.

Using these sources of hail observations, return periods are estimated for hail storms with various hail sizes in the Netherlands. Moreover, spatial differences within the Netherlands are explored based on both the written documents as well as the radar-based observations. Using this climatology, probabilities of being hit by hail with a certain size are calculated, differentiated by province. Such probabilities are of direct use for developing and evaluating risk management strategies for both the public (municipalities) and private sector (such as insurance). This becomes evident when looking, for instance, at solar panels, which serve an important role in the transition towards climate-neutral urban areas, but are also vulnerable to an (increasing) hail risk.
Interannual to millennial scale variability of the River Ammer floods and its relationship with extreme climate and solar forcing
Authors: Rimbu Norel , Ionita Monica , Lohmann Gerrit
Published: March 2020

The number and strength of weather and climate extremes, such as severe floods and droughts, have increased significantly during recent decades. Part of such increase is attributed to human-induced climate change. To better assess the role of natural and anthropogenic forcing we should put the recent climate extreme variability into a long-term perspective. We analyze the variability of extreme precipitation and temperature over Europe in connection with observed daily discharge data of the River Ammer (southern Germany) and the 5500-year flood layer record from varved sediments of the downstream Ammersee. We show that daily River Ammer floods are related to upper level  Rossby waves breaking over Europe. This process, which is related to European scale extreme precipitation and temperature anomalies, is consistent with extreme precipitation and temperature patterns associated with River Ammer floods. From a synoptic scale perspective, the observed out-of-phase relationship between solar irradiance forcing and river Ammer floods, as presented in previous studies, is related to enhanced blocking activity over Eastern Europe-western Russia during low solar forcing which favors upper level positive potential vorticity anomalies over western Europe, a more unstable atmosphere and more floods. A singular spectrum analysis of a flood layer record from lake Ammer and a total solar irradiance reconstruction, going back in time to the mid-Holocene, reveals coherent variability at ~900 years and ~2300 years. We argue that similar cycles should dominate the millennial scale variations of blocking activity in the Eastern Europe-western Russia as well as the frequency of extreme temperatures, precipitation and floods over Europe. 
ICEWISE: A game to test the effects of sea ice forecast reliability on voyage planners’ confidence
Authors: Blair Berill , Muller Malte , Palerme Cyril , Blair Rayne , Crookall David , Lamers Machiel
Published: March 2020

A group of scientists in a multi-national consortium have worked together to improve climate services for maritime actors in Arctic waters. The consortium under the project Enhancing the Saliency of climate services for marine mobility Sectors in European Arctic Seas (SALIENSEAS) running 2017-2020, has aimed to coproduce improved (sub)seasonal sea ice forecast and iceberg detection services. The project involved metservice experts and end users to collaboratively explore ways in which forecast services can reduce uncertainties for stakeholders.

However, direct questioning about perceived risks and uncertainties during operations do not always lend themselves well to traditional inquiries such as self-report surveys. Stakeholders can and do experience difficulty accurately recalling and rating past perceptions and connecting them to varying environmental conditions. As an alternative, experiential approaches such as participatory simulation are able to furnish a reliable environment that facilitates replication, experimenting and learning.

We present a novel approach with which to explore effects from the reliability of sub-seasonal sea ice forecasts on the user’s perception of uncertainties. Our methods combine anticipatory methods through the use of scenarios with participatory simulation in a computerized simulation/game called ICEWISE. In our paper we will:

introduce the game and the newly developed seasonal sea ice forecast

present results from a gaming workshop conducted with experts in Arctic marine operations

discuss the role of full and structured debriefing in maximizing the learning that takes place during gaming sessions

To conclude, we reflect on the upcoming stages of data collection, which will culminate in an exploratory model. The model will serve to inform sea ice service providers about the potential mediating effects deriving from the reliability of sea ice forecasts on the user’s own perceived confidence in successful voyage planning.   
Methane emission measurements at the North Sea
Authors: Velzeboer Ilona , Frumau Arnoud , van den Bulk Pim , Hensen Arjan
Published: March 2020

In July and November 2018 measurements campaigns were performed at the North Sea. This campaign was aimed to assess independently total methane emissions of a selected group offshore oil and gas platforms using concentration measurements at multiple distances from the source in combination with meteorological conditions and dispersion calculations. This measurement set-up is in line with methane measurements carried out near onshore gas production locations in 2016-2017.

First observations with tracer experiments showed different behavior of the plumes offshore, compared to onshore plume behavior.

The Gaussian Plume model was modified with the methodology of the Offshore and Coastal Dispersion (ODC) model, to incorporate the effect of the sea surface and the building effect of the offshore installations on the dilution and mixing of the plume. Together with the performed tracer experiments, this resulted in more reliable calculations of the source strength of methane emissions from the installations.
Rapidly accelerating subsidence in Maceió (Brazil) analayzed by multi-temporal DInSAR analysis and 2d geomechanical modeling
Authors: Vassileva Magdalena Stefanova , Al-Halbouni Djamil , Dahm Torsten , Motagh Mahdi , Walter Thomas , Wetzel Hans-Ulrich
Published: March 2020

The densely populated neighborhoods of Pinheiro, Bebedouro, Mutange, Bom Parto and Levada in the Municipality of Maceió (Brazil) are suffering serious geological instability.  Fractures, on both buildings and roads, have intensified since the beginning of 2018 and some of the areas were evacuated, due to safety reasons, by the local authorities during the second half of 2019. The preliminary investigation conducted by the Brazilian Geological Service (Serviço Geologico do Brazil - CPRM), suggested that the direct cause of the instability is connected to the salt mining activities carried out on near the cost of the Mundaú Lagoon. 

In this study we use radar interferomtery (InSAR) and 2D geomechanical modelling to characterize almost 16 years of continuous deformation in Municipality of Maceió (Brazil). We exploited the full potential of the well-known Multi Temporal Interferometry techniques (MTI) based on Advanced Synthetic Aperture Radar Differential Interferometry (A-DInSAR) and processed all available historical and currently operational SAR missions: the C-band ASAR ENVISAT, the L-band ALOS-1 POLSAR, L-band ALOS-2 POLSAR and C-band Sentinel-1 missions. The results show clear main deformation field over the neighborhood of Pinheiro with concentric pattern to the shore and increasing deformation intensity up to 25cm per year from 2003 to 2019. A minor deformation area is detected also south of the lagoon corresponding to the neighborhood of Bom Parto and Levada. A 2D geomechanical modelling of salt-cavern stability using Distinct Elements is developed to derive the relationship between the detected deformations and the salt mining activities. As a general conclusion, our study shows how MTI analysis is very efficient and reliable tool for emergency management purposes. Especially after the launch of the Sentinel-1 mission, which provides an acquisition in single pass every 12 days, we are able to detect when a surface displacement commence and monitor the deformation progress and status in time.
Towards image based assessment and characterization of cyclic paleo-wind and flow fields
Authors: Halisch Matthias , Zeeden Christian , Rolf Christian
Published: March 2020

Cylcostratigraphy is used to investigate quasi-cyclic patterns in sediments. It often provides insight about time and climate. While most studies utilize proxies related to precipitation and temperature, reconstruction of wind and flow directions is more challenging. Due to this, the dynamic change of atmospheric circulations from geophysical data is not well established on orbital timescales. One key method for this purpose is the assessment of the anisotropy of the magnetic susceptibility. Nevertheless, the so derived data are of volume-integrated nature, i.e. a result of the combined mineral composition and structure of the entire investigated sample material. Accordingly, it would be most favorable to link and assess the volume integrated data with spatial sample features. X-ray micro computed imaging enables extensive and non-destructive sample material characterization in three dimensions, with special regards to mineralogical, textural, geometrical and topological material features. By combining volume specific magnetic anisotropy data with state of the art X-ray micro CT imaging data sets, we can derive spatially resolved information about (e.g.) grain sizes, grain shapes, sorting, layering patterns, preferential grain / pore/ layer orientations, secondary precipitates, pore sizes, pore shapes and many other parameters. With this, we greatly increase our understanding about the ancient depositional environment, which is important for investigating and characterizing the dynamic and quasi-cyclic wind and flow fields.
Size distribution functions of submicron aerosol and approximation based on the direct Kolmogorov equation
Authors: Chkhetiani Otto , Gledzer Evgeny , Vazaeva Natalia
Published: March 2020

The particle size distribution function is one of the characteristics reflecting the composition of aerosol during sand lifting and removal in desert regions. This characteristic, in addition to known practical applications, is important in describing radiation processes during the exchange of heat fluxes and in forming cloud systems in the models of atmospheric dynamics. Fine dust-aerosol fractions (less than 2 µm in diameter) are especially important for the atmospheric radiation budget, because such fractions (having a significant lifetime) most efficiently interact with short-wave solar radiation. One of the central regularities in considering the size distributions of simulated dust-aerosol particles is the following formula based on the so-called fragmentation process and verified using a large amount of empirical data N (d) ~ d -2. Similar dependence for particles with size d > 1 µm is associated with the consideration of the fragmentation process as a particle splitting according to the log-normal distribution.

Results of field measurements taken in the near–Caspian (2002, 2003, 2007, 2009, 2010, 2011, 2013, 2014, 2016 years) and near–Aral-sea (1998) deserts under the conditions of weak winds (almost in the absence of saltation processes) and strong heating of the land surface are given. These results show that the fine mineral dust aerosol (0.1-1 µm) considerably contributes to the total aerosol content of the atmospheric surface layer under such conditions. The scaling of daytime mean size d distribution at a height of 2 m is close to d -5 in contrast to the law d -2 for fraction d >1 µm.

Different compositions of aerosol particles at 0.1 < d < 1 µm, and d >1 µm, including multicomponent fractions (less than 1 µm) may result in different probabilities of their integration and disintegration, which, finally, determine equilibrium particle size distributions. The simplest distribution approximations based on the Kolmogorov direct differential equation are given. 

This study was supported by the RFBR (19-05-50110) and the Presidium of the Russian Academy of Sciences (programs 12 and 20).
Mapping magnetic field and relativistic electrons along a solar flare current sheet
Authors: Fleishman Gregory , Chen Bin , Dale Gary , Nita et al. Gelu
Published: March 2020

In the standard model of solar flares, a large-scale reconnection current sheet (RCS) is postulated as the central engine for powering the flare energy release and accelerating particles. However, where and how the energy release and particle acceleration occur remain unclear due to the lack of measurements for the magnetic properties of the RCS. Here we report the first measurement of spatially-resolved magnetic field and flare-accelerated relativistic electrons along a large-scale RCS in a solar flare. The measured magnetic field profile shows a local maximum where the reconnecting field lines of opposite polarities closely approach each other, known as the reconnection X point. The measurements also reveal a local minimum near the bottom of the RCS above the flare loop-top, referred to as a "magnetic bottle". This spatial structure agrees with theoretical predictions and numerical modeling results. A strong reconnection electric field of over 4000 V/m is inferred near the X point. This location, however, shows a local depletion of microwave-emitting relativistic electrons. In contrast, the relativistic electrons concentrate at or near the magnetic bottle structure, where more than 99% of them reside at each instant. Our observations suggest crucial new input to the current picture of high energy electron acceleration.