bluuebunny/crossref_metadata_2025 huggingface dataset:
Differences between female and male researchers with fixed-term positions in Japan
Authors: Oguchi Chiaki
Published: March 2020

Fixed-term researchers, not only for female researchers but also for male researchers, have a more volatile life than non-term researchers. There are quite a few countries that are struggling with this issue, and it can be said that each country has its own characteristics. It is often said that it is necessary to take positive actions and set numerical targets for improving gender equality issues. However, in fact in Japan it is often said that "it is inverse discrimination" at the stage of submitting a request to set such numerical targets or when recruiting researchers only for women as one of positive actions. When such fact occurred, the seeds for improving gender equality actions would be pulled away before they grow up. Large-scale surveys of female researcher ratio and activities in almost all STEM fields have been conducted through EPMEWSE by 5 years intervals. The recent survey was done in 2017. The results were analyzed and reported 2018 in Japanese and 2019 in English. According to the report, the average age at which half of fixed-term female researchers can move to permanent positions is 2-3 years older than male researchers. Reflecting this, the average annual income of fixed-term female researchers is lower than that of male researchers. In this presentation, I will introduce the results of a comparison of such data between the STEM field and the earth and planetary science field.
Optimal Vertex Interval Determination for Efficient Shoreline Length Calculation
Authors: Woo Hee Sook , Kwon Kwang Seok , Kim Byung Guk
Published: March 2020

Coastline extraction and decisions have important implications for efficient land management and national policy formulation. Therefore, shorelines should be determined in a reasonable manner, and consistent results should be produced for the same area. This must be calculated efficiently. For example, simple shoreline areas should be constructed using relatively large vertex intervals (point-to-point distances) for efficiency, while complex shoreline areas should be constructed using small vertex intervals, thus improving accuracy. In this study, we suggest an optimum vertex interval that can represent more than 99.7% (3σ) of the original shoreline data using a grid generated by applying a box-counting method. All coastline areas were gridded using 11 grid sizes. Generalization was performed on the shorelines contained within each grid, and the sum of the generalized shoreline lengths was calculated. As the grid size used increases, the shoreline will become more simplified, and the difference from the original data will increase. As the grid size decreases, the more precisely the shoreline will be represented, and the sum will be similar to the original value. As a result of regression analysis, using the sum of the generalized shoreline length, we could predict the vertex interval that would represent more than 99.7% (3σ) of the original data. For the experiment, three regions with distinct coastline characteristics were selected. The grid was generated by the box-counting method, a representative fractal technique, and the vertex interval was estimated. From this, the fractal dimension was then calculated. As a result of the experiment, it was confirmed that the area A had a vertex interval of 0.7m, and the areas B and C had vertex intervals of 1m. These optimal vertex interval values mean that when the coastline was reconstructed, it was the closest, efficient representation of the actual coastline. Furthermore, these interval values suggest that the area A has a more complex coastline, and therefore the coastline should be constructed with a smaller vertex interval than the other areas. Using fractal dimensions, we also found that the area B has a more complex coastline than the area C. Overall, we confirmed that the optimal vertex interval for the accurate and efficient construction of the shoreline is able to be calculated by the approach presented in this paper. This research is expected to contribute to efficient land management and national policy establishment and progress. 
Constraints on OH in a global 3D inversion of methyl chloroform
Authors: Naus Stijn , Montzka Stephen , Patra Prabir , Krol Maarten
Published: March 2020

The hydroxyl radical (OH) is the primary atmospheric oxidant. In this role, OH is involved in the removal of a wide variety of atmospheric pollutants and greenhouse gases. Despite the central role of OH in atmospheric chemistry, important metrics such as interannual variability and trends in OH on large spatial scales remain poorly constrained. This is mainly due to its low abundance and short lifetime of seconds.

Over the past decades, the anthropogenically emitted methyl chloroform (MCF) has been uniquely qualified as a tracer to indirectly constrain OH on large spatio-temporal scales. However, recent box model studies have shown that OH, as estimated from MCF observations, is still very uncertain 1,2,3. This translates for example to large uncertainties in global methane (CH4) emissions, even if changes in the global CH4 burden are well-defined. Box model studies however, do not fully capitalize on the MCF measurement network and the gradients therein. Moreover, they may introduce biases due to incorrect or incomplete representation of atmospheric transport.

Here, we present results from a 4DVAR inversion of MCF over the 1998-2018 period, performed in the 3D chemistry-transport model TM5. Starting from typical OH priors, we find adjustments in the OH spatio-temporal distribution that bring the simulated MCF mole fractions closer to observations. Large uncertainties in this improved estimate remain, but we find that no large interannual variability (>2%) and no significant trend in global mean OH are needed to match MCF observations. We do find significant adjustments in the latitudinal gradients of OH (e.g. an increase in tropical OH).

1 Rigby, M., et al. PNAS (2017), 114.21: 5373-5377

2 Turner, A.J., et al. PNAS (2017), 114.21: 5367-5372

3 Naus, S et al. ACP (2019), 19.1: 407-424
Core Phases Observed with AlpArray
Authors: Ling On Ki Angel , Stähler Simon , Giardini Domenico , Hosseini Kasra , AlpArray Working Group The
Published: March 2020

In most seismic tomographic models, the first P and/or S wave data generated by regional and teleseismic events are used to conduct tomographic inversion. Despite the abundance and precise measurement of the first body wave arrival times, the non-uniform distribution of their ray path leads to a lower resolution in the mantle below 1000km in depth. Curiously, there are particularly few ray paths sampling the lowermost mantle below dense seismic arrays, due to the limited incidence angle range of P and S waves. Previous studies have demonstrated the importance of core phases, resulting from reflection and/or conversion of seismic waves at the core discontinuities, in seismic tomography by improving the ray path coverage and constraining the structures in the lower mantle. Therefore, adding core-grazing phases (Pdiff, Sdiff) as well as core phases (e.g. PKP, PKIKP, SKS) in tomography could deliver high-resolution tomographic images of deep mantle structures in poorly resolved regions and may even reveal undiscovered features.

To increase the topographic resolution in the Alpine region, the AlpArray Initiative deployed about 250 temporary stations alongside the local permanent stations in the European Alps forming a greater AlpArray seismic network. This large-scale network provides a dense sampling rate and high-quality seismic data across the region, which gives us a unique opportunity to observe core phases coming from all directions in such a large aperture. We investigate the visibility of core phases observed with AlpArray and find that it is uniquely suited to observe high order core phases (P’P’, PcPPcPPKP, PKPPKPPKP) from sources in Alaska, Japan, and Sumatra in a distance range of 60-110 degrees. We show some array processing methods to improve the resolution of seismic observation and examine the waveforms in different frequency ranges. We find significant deviations in core phase amplitudes from predictions which are most likely linked to other structures directly above the core mantle boundary and can serve to test tomographic models in this depth region. The insight gained from this modelling is used to discuss the usability of core phases in future tomographic studies.
What do we know about how the terrestrial multicellular soil fauna reacts to microplastic?
Authors: Büks Frederick , van Schaik Loes , Kaupenjohann Martin
Published: March 2020

The ubiquitous accumulation of microplastic particles across all global ecosystems comes along with the uptake into soil food webs. In this work, we evaluated studies on passive translocation, active ingestion, bioaccumulation and adverse effects within the phylogenetic tree of multicellular soil faunal life. The representativity of these studies for natural soil ecosystems was assessed using data on the type of plastic, shape, composition, concentration and time of exposure.

Available studies cover a wide range of soil organisms, with emphasis on earthworms, nematodes, springtails, beetles and lugworms, each focused on well known model organisms. Most of the studies applied microplastic concentrations similar to amounts in slightly to very heavily polluted soils. In many cases, however, polystyrene microspheres have been used, a combination of plastic type and shape, that is easily available, but do not represent the main plastic input into soil ecosystems. In turn, microplastic fibres are strongly underrepresented compared to their high abundance within contaminated soils. Further properties of plastic such as aging, coating and additives were insufficiently documented. Despite of these limitations, there is a recurring pattern of active intake followed by a population shift within the gut microbiome and adverse effects on motility, growth, metabolism, reproduction and mortality in various combinations, especially at high concentrations and small particle sizes.

For future experiments, we recommend a modus operandi that takes into account the type, shape, grade of aging and specific concentrations of microplastic fractions in natural and contaminated soils as well as long-term incubation within soil mesocosms.
Problem ot the energy transfer for radio paths near single-hop limiting distance for low solar activity
Authors: Atamaniuk Barbara , Krasheninnikov Igor V. , Popov Alexei , Matyjasiak Barbara
Published: March 2020

Formation the feature, in a form of deep trough, in frequency dependence
of the wave field strength for single-hop paths with distances near
classical limiting distance 3000 km at low level of solar activity was
considered. Model calculations within the framework of the extended global
ionospheric IRI model show high probability for appearing such situation
in the local daytime with a developed regular E-layer of the ionosphere.
Some experimental results in multifrequency radio sounding of the
ionosphere with a registration of the deep trough in frequency dependence
of signal-to-noise ratio (SNR) were analyzed. It is shown that the IRI
model, in principle, makes it possible to reproduce this peculiarity in
the wave field energy parameters, but in some cases of experimental data,
to a large extent, is able to provide only a qualitative description of
this effect. Possible reasons for the quantitative discrepancy between
experimental and model results are discussed.
Solar Wind Turbulence at Kinetic Scales in the inner Heliosphere
Authors: Alexandrova Olga , Jagarlamudi Vamsee , Maksimovic Milan , Hellinger Petr , Shprits Yuri , Mangeney Andre
Published: March 2020

We study magnetic fluctuations at sub-ion scales and down to sub-electron scales using Helios/SCM measurements in the inner Heliosphere and Cluster/STAFF data at the Earth's orbit. Using these data we test the generality of the kinetic spectrum and we show that it follows the ~k-8/3exp(-kld) law at different radial distances from the Sun (k being a wavenumber). We show as well that the dissipation scale ld correlates well with the electron Larmor radius ρe at 0.3 AU and at 1 AU. Then, in the time domain, at 1 AU, using the wavelet transform, we study the nature of magnetic fluctuations, which form the kinetic spectrum. It appears, that the spectrum is dominated by non-linear coherent structures in the form of magnetic vortices with the smallest resolved scale of the order of ρe. Finally, we comparer our results with measurements of the Parker Solar Probe/FIELDS and, hopefully, of the Solar Orbiter/RPW in the inner Heliosphere.
Dynamics of a barotropic current at an ice shelf front
Authors: Steiger Nadine , Darelius Elin , Kimura Satoshi , Patmore Ryan , Wåhlin Anna
Published: March 2020

Ice shelves in West Antarctica are melting at an increasing rate due to the flow of relatively warm
Circumpolar Deep Water into the ice shelf cavities. The current that brings heat southward along the
eastern side of a trough towards an ice shelf front is found to have a barotropic and a baroclinic
component. Mooring observations in front of Getz Ice Shelf suggest that 90% (roughly 0.6 Sv) of the
volume transport and 65% of the temperature transport is linked to the barotropic component of the
current towards the ice shelf. It is unknown whether and how much of a barotropic current can
penetrate under the ice shelf across the about 300 m deep ice shelf front, where lines of constant water
column thickness discontinue.
We conduct idealized modelling with MITgcm to investigate the dynamics of a barotropic current at the
ice shelf front. Friction and strong vertical velocities at the ice shelf front break the potential vorticity
constraint and allow the flow to partly enter the ice shelf cavity. Only a small fraction of the current
penetrates deep into the cavity, while a strong current flows parallel to the ice shelf front, where basal
melt is largely enhanced. How much of the current enters the cavity and how far it reaches depends on
the ice shelf- and bedrock topography.
Comparing high-sensitivity geophones to fiber-optic DAS technologies in a hard-rock VSP survey
Authors: Lund Björn , Stork Anna , Roth Michael , David Ari , Clarke Andy , Nygren Carl , Johansson Sam
Published: March 2020

As part of the preparations for a microseismic network on the planned nuclear waste repository in Forsmark, Sweden, we carried out a suite of measurements for site characterisation and instrument testing using geophones and DAS fiber-optic technology. Three high-sensitivity 240 V/m/s geophones were grouted into a 200 m deep borehole together with a linear, a helical and a helical engineered fiber-optical cable. Two different interrogators were used for DAS acquisition. We performed a walk-away vertical seismic profile (VSP) survey with 10 m source spacing out to 1.1 km offset and compare the responses of the four different measurement systems. The complete transfer functions of the fiber-optic systems have not yet been determined, and depend on factors such as incidence angle, signal frequency content and the fiber gauge length. Preliminary results show that all systems record signals with high signal-to-noise ratio and that which system has highest performance depends on source-receiver distance, signal frequency content and wave incidence angle. Due to incomplete knowledge of the fiber transfer functions we cannot match the DAS velocity signal with the geophone signal. Investigation of the detection capabilities of the fiber and geophone systems is underway and will be presented together with a discussion of the relative merits of the various systems for microseismic monitoring.
Bifurcations, Global Change, Tipping Points and All That
Authors: Ghil Michael
Published: March 2020

In this talk, we will attempt to cover, as time permits, issues pertaining to a self-consistent, unified treatment of the climate system’s natural and forced variability, i.e. climate change, sensitivity and intrinsic variability. To set the stage, key features of short-, intermediate, and long-term prediction will be sketched, followed by the effects of the system’s multiple scales of motion. After summarizing the main results and uncertainties of successive assessment reports of the International Panel on Climate Change (IPCC), time-dependent forcing will be introduced, in both its natural and anthropogenic forms.

   We will outline the generalization of strange attractors to this non-autonomous setting, namely pullback and random attractors (PBAs & RAs), as well as the generalization of the bifurcations known from classical, autonomous dynamical systems to the tipping points (TPs) of non-autonomous ones. The case of the Lorenz convection model with stochastic forcing and of its RA will be used as an illustrative example. The talk will conclude with a list of questions and a selected bibliography.
Effect of the water layer on seismic noise cross-correlation across the Northeast Atlantic, from Madeira and Canaries to the Atlas-Gibraltar zone
Authors: Silveira Graça , Carvalho Joana , Pinzon Juan , Custódio Susana , Corela Carlos , Matias Luís
Published: March 2020

One of the aims of project SIGHT (SeIsmic and Geochemical constraints on the Madeira HoTspot system) is to obtain a 3D model of SV-wave velocities of the crust and upper mantle of the Northeast Atlantic area encompassing Madeira and Canary Islands to the Atlas-Gibraltar zone, using seismic noise cross-correlations in the period range 2-100 s. Ambient noise cross-correlation has been successfully applied in a variety of tectonic environments to image the structure of the Earth subsurface. This technique overcomes some limitations ascribed to source–receiver geometry and sparse and irregular earthquake distribution, allowing to image Earth structure with a resolution that mainly depends on the network design. However, the effect of the water layer in the short period Empirical Green Functions, which are obtained by seismic noise cross-correlation, for interstation paths crossing the ocean is still poorly understood.

In several studies, it has been observed that the presence of water and sediments is responsible for later wave-train arrivals. Those later arrivals are frequently disregarded when measuring group velocity, either by considering only longer periods or by specifying a given velocity range.

In this work, we present a systematic study of the influence of the water layer on both vertical and radial synthetic Rayleigh waves, as well as on higher-mode conversion and on the group velocities dispersion measurements.

We show that although the fundamental mode dominates, the presence of the first overtones at short periods (typically below 8 seconds) cannot be neglected. We also show that specifying a given velocity range when retrieving group velocity can result in a mixture of modes. Our tests reveal that, at short periods, the water has a dominant effect on ocean-continent laterally varying media.

This is a contribution to projects SIGHT (Ref. PTDC/CTA-GEF/30264/2017) and STORM (Ref. UTAP-EXPL/EAC/0056/2017). The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL.
Avalanche flow regime transitions in a changing climate
Authors: Ligneau Camille , Sovilla Betty , Gaume Johan
Published: March 2020

In the near future, climate change will impact the snow cover in Alpine regions. Higher precipitations and warmer temperatures are expected at lower altitude, leading to larger gradients of snow temperature, snow water content and snow depth between the top and the bottom of slopes. As a consequence, climate change will also indirectly influence the behavior of snow avalanches.

The present work aims to investigate how changes in snow cover properties will affect snow avalanches dynamics. Experimental studies allowed to characterize different avalanche flow regimes which result from particular combinations of snow physical and mechanical properties. In particular, expected variations of snow temperatures with elevation will cause more frequent and more extreme flow regime transitions inside the same avalanche. For example, a fast avalanche characterized by cold and low-cohesive snow in the upper part of the avalanche track will transform more frequently into a slow flow made of wet and heavy snow when the avalanche will entrain warm snow along the slope. A better understanding of these flow regime transitions, which have already been largely reported, is crucial, because it affects both daily danger assessment (e.g. forecasting services, road controls) and hazard mapping of avalanches.

To date, most avalanche modeling methods are not considering temperature effects and are then unable to simulate flow regime transitions and unprecedented scenarios. Our goal is then to develop a model capable of simulating reported flow regimes, flow transitions and the interactions between the snow cover and the flow (erosion, entrainment). Since these elements are not yet fully understood, we firstly model these mesoscopic processes using a 2D Discrete Element Model (DEM) in which varying particle cohesion and friction mimic the effect of changes in snow temperature. Flow regimes are simulated by granular assemblies put into motion by gravity on an inclined slope, which interact with a granular and erodible bed surface. Simulations are calibrated using experimental data coming from the avalanche test site located in Vallée de la Sionne, which record avalanches since more than 20 years. This modeling will then be used as an input to improve slope-scale models and make them more appropriate for avalanche risk management in the context of climate change.
Monitoring of river discharge through the combination of multiple satellite data: RIDESAT project
Authors: Tarpanelli Angelica , Nielsen Karina , Filippucci Paolo , Belloni Rossella , Camici Stefania , Brocca Luca , Moramarco Tommaso , Restano Marco , Benveniste Jérôme
Published: March 2020

RIDESAT - RIver flow monitoring and Discharge Estimation by integrating multiple SATellite data, is an ESA-funded Permanent Open Call project aimed to develop a new methodology for estimating river discharge through the combination of radar altimeter, optical and thermal satellite sensors. The combination of multi-sensor measurements can provide significant advantages over single sensors contributing to improve the quality of the final products also in terms of spatial and temporal coverage.

The methodology developed in the project includes two phases. First, the single-instrument products (altimeter, optical and thermal sensors) are independently processed to generate a dataset of proxies of hydraulic variables strongly linked with river discharge (e.g. water level, flow velocity, width). Successively, these proxies are implemented as integrated techniques for the final estimation of the river discharge.

To test the ability of the approach to retrieve river discharge at global scale, 20 pilot sites are selected all over the world, based on the availability of in-situ measurements and the climatic characteristics of the basins. The availability of large datasets of in situ measurements is used for: 1) the validation of single-instrument products and the river discharge product; 2) the evaluation of the uncertainty attributed to the combination process; 3) the evaluation of the limitation of the procedure.
Modelling infrasonic ocean ambient noise using NWP and lidar observations in southern Argentina
Authors: Ceranna Lars , Hupe Patrick , de Carlo Marine , Le Pichon Alexis
Published: March 2020

In routine processing of infrasound data of the International Monitoring System, coherent ocean ambient noise with dominant frequencies ranging from 0.1 to 0.5 Hz appears in overlapping frequency bands. These signals, so-called microbaroms, originate from complex wave interactions. In this study, microbarom detections are used as calibration signals, and their amplitudes at the Argentinian infrasound station IS02 are modelled based on operational ocean wave interaction simulations and a semi-empirical attenuation relation. This relation strongly depends on the middle atmosphere (MA) dynamics. Previous studies have shown that the MA wind and temperature are not properly resolved in numerical weather prediction (NWP) models. Therefore, high-resolution soundings of the Compact Rayleigh Autonomous Lidar (CORAL) are incorporated in the modelling. The infrasound data are processed using the progressive Multi-Channel Correlation (PMCC) algorithm.

This sensitivity study focuses on one year of collocated infrasound and lidar measurements in southern Argentina. It highlights the seasonal effects of MA uncertainties on infrasound propagation and detections in 2018.
The response of vegetation to rising CO2 concentrations plays an important role in future changes in the hydrological cycle
Authors: Hong Tao , Ji Dong
Published: March 2020

The effects of increasing CO2 concentrations on plant and carbon cycle have been extensively investigated; however, the effects of changes in plants on the hydrological cycle are still not fully understood. Increases in CO2 modify the stomatal conductance and water use of plants, which may have a considerable effect on the hydrological cycle. Using the carbon–climate feedback experiments from CMIP5, we estimated the responses of plants and hydrological cycle to rising CO2 concentrations to double of pre-industrial levels without climate change forcing. The mode results show that rising CO2 concentrations had a significant influence on the hydrological cycle by changing the evaporation and transpiration of plants and soils. The increases in the area covered by plant leaves result in the increases in vegetation evaporation. Besides, the physiological effects of stomatal closure were stronger than the opposite effects of changes in plant structure caused by the increases in LAI (leaf area index), which results in the decrease of transpiration. These two processes lead to overall decreases in evaporation, and then contribute to increases in soil moisture and total runoff. In the dry areas, the stronger increase in LAI caused the stronger increases in vegetation evaporation and then lead to the overall decreases in P − E (precipitation minus evaporation) and soil moisture. However, the soil moisture in sub-arid and wet areas would increase, and this may lead to the soil moisture deficit worse in the future in the dry areas. This study highlights the need to consider the different responses of plants and the hydrological cycle to rising CO2 in dry and wet areas in future water resources management, especially in water-limited areas.
High Energy (>10 MeV) Oxygen and Sulfur Ions Observed at Jupiter from Pulse Width Measurements of the JEDI Sensors
Authors: Westlake Joseph , Clark George , Haggerty Dennis , Jaskulek Stephen , Kollmann Peter , Mauk Barry , Mitchell Donald , Nelson Kenneth , Paranicas Chris , Rymer Abigail
Published: March 2020

The Jovian polar regions produce X-rays that are characteristic of very energetic oxygen and sulfur that become highly charged on precipitating into Jupiter’s upper atmosphere.  Juno has traversed the polar regions above where these energetic ions are expected to be precipitating revealing a complex composition and energy structure. Energetic ions are likely to drive the characteristic X-rays observed at Jupiter (Haggerty et al., 2017; Houston et al., 2018; Kharchenko et al., 2006). Motivated by the science of X-ray generation, we describe here Juno JEDI measurements of ions above 1 MeV, and demonstrate the capability of measuring oxygen and sulfur ions with energies up to 100 MeV. We detail the process of retrieving ion fluxes from pulse width data on instruments like JEDI (called “puck’s”; Clark et al., 2016; Mauk et al., 2013) as well as details on retrieving very energetic particles (>20 MeV) above which the pulse width also saturates. The Juno JEDI instrument is shown to have the unplanned capability to measure heavy ions to energies as high as 100 MeV. As such, the JEDI instrument has the capability to measure those ions needed to generate polar X-rays at Jupiter. (> 10’s of MeV O and/or S). We present analysis that involves separating these very energetic ions into the group that is trapped (i.e., part of the very high latitude radiation belts) and the group that is precipitating and might be linked to observed X-rays.
Flow modeling within a Central European forest using large-eddy simulation
Authors: Plorin Max , Grunicke Sandra , Bernhofer Christian , Queck Ronald
Published: March 2020

With the aim to simulate the exchange of energy and matter between air and vegetation, we applied the LES PALM to a typical Central European forest. The presentation shows how the level of detail within vegetation model and the orography alters the simulated flow.

The site of investigation is a managed mixed forest stand (mainly Picea abies, height 30 m; a long-term CarboEurope monitoring site) within the Tharandter Wald near Dresden, Germany. Terrestrial laser scans (TLS) provided the data basis for the high-resolution vegetation model of this forest stand and a nearby clearing (50x90 m) building the inner range of the model domain. To investigate orographic effects on the flow, we extended the domain for about 1.5 km to the west. This includes the S-Berg, which is about 40 m height and therefore the highest elevation on the windward side. We used information from airborne laser scanning (ALS) along with forest inventory data to build a vegetation model as well as a digital elevation model for the extended area (2 km in streamwise and 1.5 km in lateral direction) with a resolution of (2m)3. 

In a first step, we restricted all simulations to a neutral atmosphere to exclude effect of buoyancy.

Wind data from four measurement towers (from DFG SPP 1276 MetStröm) provided data for a validation of the simulations. They were located within the inner domain along a west-east transect over the clearing.
Assessment of the trace element composition of peat soils from the European Arctic in a changing climate conditions
Authors: Vasilevich Roman
Published: March 2020

The trace element composition of stratified peat soils is interesting for the reconstruction of the geochemical background of atmospheric aerosol. The monitoring of trace element contents in peat deposits is often used for the identification of pollution around large industrial centers. The destabilization of the peatlands of the cryolithozone presents a global environmental hazard of the input of inorganic pollutants into the hydrologic network and their subsequent transport into the Arctic Ocean. Climate warming and permafrost degradation enhance the influence of deep peat layers on the trace element composition of groundwater and rivers. The purpose of the work is to assess the accumulation of trace elements in peat soils as a result of the aerogenic pollution of the territory and to identify their internal profile migration and accumulative characteristics. The peatlands investigated are in the far north taiga (Northeastern European Russia, 65°54′ N, 60° 26′ E), ecoton south tundra – forest-tundra (67°03′ N, 62° 56′ E) and ecoton north tundra – south tundra (68°02′ N, 62° 43′ E). The upper level of trace element accumulation was confined to the active (seasonally thawed) layer owing to airborne contamination over a long time span and related to the bioaccumulation of Hg, Cd, Pb, Cu, and other heavy metals (HMs) by plants and humus materials. The character of element accumulation and migration in the active layer is controlled by the stability of HM humates. Under high-acidity conditions, HMs are highly mobile and migrate to the lower boundary of the active layer, which is indicated by an increase in the fraction of water-soluble forms of a number of elements. Analysis with a scanning electron microscope revealed the presence of spherical and semispherical particles up to 1 μm in size containing Pb, Zn, Cr, and Ni in the upper peat levels, which indicates an anthropogenic source of their input owing to long-distance and local transport of air masses. The central level of element accumulation was confined to peat layers in the permafrost zone (60–120 cm), where enrichment in As and Cd relative to the mean contents in the Earth’s crust (and approximate permissible concentrations, APC, for soils) and accumulation of Fe, Al, S, and siderophile elements were observed. The source rocks of the peatlands are loams enriched in Cd, Zn, and As. The statistical analysis of relations of the contents of major and trace elements in the stratified peat horizons with the composition of peat-forming materials showed a significant contribution of the biogenic accumulation of elements. The reported study was funded by the RFBR No 18-05-60195 (No AAAA-A18-118062090029-0).
Multi-year observations of calving and front characteristics of two marine terminating outlet glaciers
Authors: Walter Andrea , Lüthi Martin P. , Funk Martin , Vieli Andreas
Published: March 2020

We observed two outlet glaciers in West- and Nordwest-Greenland with a terrestrial radar interferometer (TRI), pressure sensors and time-lapse cameras over six and two years, respectively. The resulting detailed dataset provides us with insights on the calving process and the changes in front geometry over the last years. Since the two glaciers are characterised by different geometries and velocity fields, the influence of those parameters on the calving process can be investigated. The combination of the three different observation methods enable us to overcome their individual disadvantages. With the time-lapse camera taking pictures of the glacier front every 10 seconds, we detect all calving events of different sizes and styles but cannot quantify the volume. We used the TRI to quantify the volumes of aerial calving events by DEM differentiation. Further, calving waves measured with pressure sensors are used to distinguish between different calving types. We develop a relationship between calving volumes and wave heights and use this as an additional indirect method to estimate calving volumes. We find that the calving style and size as well as the front geometry is mainly controlled by the bed topography and the presence of a subglacial discharge plume. The location of the plume is observed to migrate from year to year, which leads also to changes in the calving pattern. Calving style and pattern as well as glacier velocity fields and geometry changes are additionally compared with environmental conditions such as the air temperature and the presence of ice-mélange in the proglacial fjord. In years with an early spring we find different front characteristics and calving patterns than for years with colder conditions.
Investigation of the photochemical activity in different MPC outflows during EMeRGe
Authors: George Midhun , Andrés Hernández Maria Dolores , Liu Yangzhuoran , Nenakhov Vladyslav , Philip Burrows John , Bohn Birger , Förster Eric , Zahn Andreas , Schlager Hans , Ziereis Helmut , Schreiner Benjamin , Pfeilsticker Klaus
Published: March 2020

Since peroxy radicals are closely involved in a number of tropospheric chemical processes like O3 budget, hydrocarbon oxidation and acid formation, the accurate measurement of these radicals can provide essential information to improve our understanding of processing and transformation of polluted outflows from megacities and Major Population Centres (MPCs).

Airborne measurements of the total sum of peroxy radicals, RO2*  = HO2 + ∑ RO2, where R is an organic group, were conducted in Europe in summer 2017 and in East Asia in spring 2018 within the EMeRGe (Effect of Megacities on the Transport and Transformation of Pollutants on the Regional to Global Scales) project by using the PeRCEAS instrument (Peroxy Radical Chemical Enhancement and Absorption Spectrometer), on board of the HALO research aircraft (www.halo.dlr.de).

Over the course of both measurement campaigns different MPC outflows were investigated including among others, London, Rome, Manila and Taipei. Polluted air masses of different origin and composition were probed. Overall the peroxy radical mixing ratios were of the same order of magnitude in the air masses probed in Europe and in East Asia. The variations in the photochemical activity were studied by taking into account simultaneous observations of radical precursors and photolysis rates, while applying known oxidation mechanisms. Radical precursors, photolysis rates and aerosol load were generally higher in Asia, which might indicate higher radical loss reactions on the aerosol surface than in Europe. Moreover this study shows a clear deviation in the photostationary state for MPC outflows close to the emission sources. Based on this information, this presentation will focus on the actual understanding of the photochemical processing in the probed air masses.
Certimus, a seismic station optimized for rapid deployment in rugged terrain
Authors: Balon Marie , Filippi Sofia , Mohr Sally , Hill Phil , Watkiss Neil
Published: March 2020

Operators of broadband seismic stations, particularly in hostile locations, are restricted in experiment design and deployment time-frames by the significant constraints of historical instrumentation. Manufacturers need to move away from the strict requirements on tilt tolerance and associated performance compromises, fixed frequency responses, unfriendly interfaces, slow data downloads and power-hungry systems in favour of simple, flexible and smart instruments that allow the operator to focus on the science at hand.

This transition is already happening with the evolution of seismic monitoring towards compact technologies: rapid-response deployments have, in recent years, become more and more feasible. However, installing low-noise, broadband instruments in remote areas has remained a challenge: low-noise force-balance broadband seismometers are typically heavy and delicate. They require significant infrastructure and logistics.

By developing the standalone, compact Certimus - with the same level of performance as traditional force-balance broadband seismometers - Güralp now offers researchers the opportunity to further push the boundaries of seismic monitoring and deploy stations in more and more challenging environments.

Unique sensor components allow Certimus to function up to 90 degrees tilt, removing the need for time-consuming centring, and allowing the station to be placed in small, hand-dug shallow holes. In 1s mode, the sensor will settle quickly and reliable data can be available in a matter of hours.  The frequency range is fully configurable in the long-period corner to allow this level of flexibility: 120s, 10s and 1s to 100Hz.

Certimus offers easy ways to check installation integrity – State-of-Health and live waveforms – before leaving the site: both with the surface and the burial variants, either via Bluetooth, LCD screen or Web Interface.

Since power consumption is a major limitation, Certimus comes with an ultra-low power mode (under 300mW) and a rugged battery module to gain up to six weeks of data before retrieval – or before a permanent power supply is arranged.

All files are recorded in industry standard miniSEED format making data download and management simplistic and universal. The metadata auxiliary channels record a vast range of state of health parameters to ensure optimal qualification of the seismic data with the environmental conditions of the seismic station.

All these advanced features are gathered in a compact, lightweight case that can be carried with all its accessories in a backpack to the most inaccessible areas. Quality seismic data is made available swiftly from anywhere, anytime.
Ground deformation associated with the August 2019 eruption of Piton de la Fournaise (La Réunion Island) inferred from DInSAR measurements
Authors: De Novellis Vincenzo , Casu Francesco , De Luca Claudio , Manzo Mariarosaria , Monterroso Fernando , Valerio Emanuela , Lanari Riccardo , Battaglia Maurizio
Published: March 2020

Piton de la Fournaise volcano forms the southeastern part of La Réunion, an oceanic basaltic island in the southernmost part of Mascarene Basin (Indian Ocean). Five eruptions occurred at Piton in 2019, accompanied by seismic activity, lava flow, and lava fountaining. Here below, we focus on the fourth eruption occurred between August 11 and 15 on the southern-southeastern flank of the volcano, inside the Enclos Fouqué caldera. This eruption was characterized by the opening of two eruptive fissures. We retrieve the surface deformations induced by the eruptive activity through space-borne Differential Synthetic Aperture Radar Interferometry (DInSAR) measurements. First, we generated the coseismic deformation maps by applying the DInSAR technique to SAR data collected along ascending and descending orbits by the Sentinel-1 constellation of the European Copernicus Programme. The DInSAR technique allows us to analyze the deformation patterns caused by the 11 August 2019 eruption. We also retrieved the pre-eruptive deformation through the Small BAseline Subset (SBAS) DInSAR approach. Then, we modelled the DInSAR displacements to constrain the geometry and characteristics of the eruptive source. The modelling results suggest that the observed deformation can be attributed to the interaction between a shallow magma reservoir located at ~1.5-2 km depth below the summit, and the intrusion of a dike feeding the eruptive fissure inside the Enclos Fouqué caldera.

This work is supported by: the 2019-2021 IREA-CNR and Italian Civil Protection Department agreement; the EPOS-SP project (GA 871121); and the I-AMICA (PONa3_00363) project.
Spatial analysis of ground-based sun induced fluorescence data and canopy pigment content in a dry grassland
Authors: Fóti Szilvia , Balogh János , Pintér Krisztina , Nagy Zoltán
Published: March 2020

Monitoring of canopy photosynthetic performance in optimal and stress conditions has major importance in carbon budget estimates or in precision agriculture. Photosynthesis responds very rapidly to the environmental conditions balancing photochemical processes with different other processes through which excitation energy is lost from the system, including photo-protective heat loss and fluorescent light emission. Although the ratio of photosynthesis to fluorescence in optimal and stress conditions differ, it is not an easy task to assess their actual share, because of the quick adjustment of the pigment-protein complexes or the changing intensity of light re-absorption by chlorophylls.

Sun induced fluorescence (SIF) measured by ground-based instrument provided direct data of the photosynthetic capacity of the canopy. The O2 absorptions bands filled with fluorescence served to calculate actual fluorescence intensity within the total upwelling signal. Furthermore, field leaf samples were collected and laboratory analysis was performed to determine photosynthetic pigment contents (both chlorophylls and carotenoids).

The sampling, both for SIF and pigment data collection followed spatial grid arrangements with different resolutions, 10 × 10 m and 30 × 30 m. Spatial analysis lays on a relatively large number of samples, collected within a very short time period. Our aim was to link the spatial distribution of one target phenomenon to the distribution or intensity of different driving forces, such as terrain features, soil moisture content, soil temperature etc., which were also simultaneously collected in the field work. One measuring occasion at both spatial scales were selected for detailed spatial data processing with geostatistics and kriging.
An atmospheric boundary layer model to improve air-sea interactions in eddying ocean models
Authors: Samson Guillaume , Lemarié Florian , Brivoal Théo , Bourdallé-Badie Romain , Giordani Hervé , Redelsperger Jean-Luc , Madec Gurvan
Published: March 2020

High-resolution ocean-atmosphere coupled models are able to simulate realistically air-sea interactions taking place at mesoscale between ocean eddies and fronts, and the lower atmosphere. These coupled processes have the potential to improve oceanic simulations by modulating wind work input and turbulent heat fluxes. However, the computational cost and the complexity of such coupled models appear prohibitive and inadequate in the context of global eddying oceanic simulations.

We propose here an alternative approach based on a one-dimensional vertical atmospheric boundary layer (ABL) model driven by large-scale atmospheric data (forecasts or reanalysis). Its intermediate complexity between a bulk parameterization and a full atmospheric model associated with a limited computational cost makes this approach well suited for applications ranging from process studies to global operational oceanography.

First, the ABL model is validated against a set of classic atmospheric testcases such as a SST front. The comparison with analytical and LES solutions indicates a good agreement with the ABL model results.

Then, two realistic configurations based on NEMO ocean model are presented to assess air-sea interactions: a global 1/4° configuration including sea-ice and a regional 1/36° configuration covering western Europe.

We show that the ocean-ABL coupled model produces negative correlations between surface current and wind stress mesoscale curl anomalies (oceanic eddy damping effect), and positive correlations between surface current and wind speed mesoscale curl anomalies (wind adjustment and ocean re-energization effects) in good agreement with literature. We also show that the simulated wind speed positively correlates with SST mesoscale anomalies, as observed with satellite data and full coupled models.

To summarize, the ocean-ABL coupled model is able to realistically represent mesoscale dynamical and thermal feedbacks while keeping a good consistency with the atmospheric forcing, and with a very limited computational cost (10% of the ocean model). The ABL model will be released with the next NEMO version.

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