bluuebunny/crossref_metadata_2025 huggingface dataset:
Template matching applied to the seismicity of the Albstadt Shear Zone, SW Germany
Authors: Mader Sarah , Brüstle Andrea , Ritter Joachim R. R. ,   the AlpArray Working Group
Published: March 2021

The Swabian Alb near the town of Albstadt, SW Germany, is one of the seismically most active regions in Central Europe. Since the beginning of the twentieth century continuous seismic activity is observed. At least three earthquakes with magnitudes greater than 5 occurred, causing major damages on the buildings in the closer vicinity. Despite of the size of these earthquakes no rupture structures are visible on the Earth’s surface. Earthquake locations are concentrated along a N-S striking zone, the so-called Albstadt Shear Zone (ASZ), at focal depths of about 1 km to 18 km. The central part of this seismogenic zone has an extension of approximately 20 km to 30 km and is characterized by dominantly sinistral strike-slip focal mechanisms.

The State Earthquake Service of Baden-Württemberg (LED) operates a dense seismic network of 6 high-gain and 9 strong-motion stations in the area of the ASZ. In 2015 and in 2018, 9 temporary high-gain stations were deployed nearby the center structure of ASZ within the framework of AlpArray Project and StressTransfer Network. This densified seismic network gives a unique opportunity to detect and locate the seismically active structures of the ASZ in more detail.

Therefore, a template matching algorithm is applied for microseismic earthquake detections. Results are compared with the existing earthquake catalog of the LED and statistics of the outcome are presented.
The effect of grain size and porosity on compaction localisation in high-porosity sandstones
Authors: Rice-Birchall Elliot , Faulkner Daniel , Bedford John
Published: March 2021

As sandstone reservoirs are depleted, the pore pressure reduction can sometimes result in pore collapse and the formation of compaction bands. These are localised features which can significantly reduce the bulk permeability of the reservoir and are therefore problematic in the oil, water, geothermal, and CO2 sequestration industries. However, the influence that grain size, grain shape and sorting have on compaction band formation in sandstone is still poorly understood, due to the fact that finding natural sandstones with specific properties is challenging. Consequently, a method of forming synthetic sandstones has been developed, in order to produce a suite of sandstone specimens with controlled grain size and porosity characteristics. During production of the synthetic sandstones, amorphous quartz cement and sodium chloride are precipitated between sand grains as a product of the reaction between sodium silicate and hydrochloric acid. The salt can then be dissolved, resulting in synthetic sandstones that have very comparable physical properties to their natural counterparts. In this study, triaxial experiments were performed on synthetic sandstone cores with four different grain size ranges of 250-300, 425-500, 600-710 and 850-1000 microns, at three different starting porosities of 27%, 32% and 37%. The samples were each axially loaded from a point along their hydrostat corresponding to 85% of their hydrostatic yield point, P*, values. These conditions mean that failure will occur within the shear-enhanced compaction regime so as to try and produce localised compaction structures. All samples were taken to 5% axial strain. The microstructural results indicate that localisation of deformation within the samples did occur and was favoured in the low starting porosity, small grain size samples. Localisation of deformation was most easily recognised by grain size reduction through grain crushing. This was weakly correlated to a change in porosity but recognition of the localisation of deformation was difficult to make using variations in porosity alone. Porosity reduction was not necessarily associated with a reduction in grain size. With increasing grain size and starting porosity, the deformation becomes more distributed in the samples with the highest starting porosity samples (37%) exhibiting more widely distributed grain crushing which was less intense overall. The results indicate a significant grain size and starting porosity influence on localisation, but also that compaction can occur by two mechanisms; one involving mostly grain rearrangement and the other primarily by grain fracturing. Consequently, the localisation of deformation is most evident in grain size reduction and is only weakly shown by porosity reduction.
Filling the Moho gap: High resolution crustal structure of the Eastern Alps
Authors: Mroczek Stefan , Tilmann Frederik , Pleuger Jan , Yuan Xiaohui , Heit Ben ,   the AlpArray Working Group
Published: March 2021

The dense SWATH-D seismic network in the Central-Eastern Alps gives an unprecedented window into the collision of the Adriatic and European plates. Previous studies have suggested a Moho gap overlying a subduction polarity switch. This switch, from European subduction in the west to Adriatic subduction in the east, was suggested by teleseismic tomography where low velocity zones in the mantle were interpreted as two slabs with opposite subduction polarity. The TRANSALP profile at 12°E indeed showed a gently southward dipping European Moho truncated by a nearly flat Adriatic Moho in receiver function (RF) images, which clearly indicated southward directed subduction. In contrast, RF images derived from the EASI profile at 13.3°E were interpreted to show Moho topography consistent with underthrusting Adriatic Moho, which would support the hypothesized polarity switch, but the image is actually ambiguous. 

We apply the receiver function method to stations in the dense SWATH-D broadband seismic network, covering approximately the area from 45-49°N and 10-15°E, supplemented by the AlpArray Seismic Network and the EASI data. We construct common conversion point stacks in order to pick the Moho conversion and its multiples.  The 15 km average station spacing has allowed us to fill in areas where previously the Moho was too weak to image. In this more comprehensive image, the asymmetry of the Moho in the TRANSALP profile can be traced to continue to at least the longitude of the EASI profile, suggesting continued southward-directed underthrusting of the European crust along the extent of the Eastern Alps, in conflict with the popular polarity switch hypothesis. At the eastern border of our study area we capture a sharp transition from European to extended Pannonian crust. Here the Adriatic Moho retreats and dips below the Pannonian Moho as it continues beneath the Dinarides.
A downscaling framework for precipitation nowcasting by merging radar retrievals at different scales and resolutions
Authors: Deidda Roberto , Farris Stefano , Badas Maria Grazia , Marrocu Marino , Massidda Luca , Seoni Alessandro , Urru Salvatore , Viola Francesco
Published: March 2021

Convective rainfall events represent one of the most critical issues in urban areas, where numerical weather prediction models are affected by a large uncertainty related to the short temporal and spatial scales involved, thus making early warning systems ineffective. Conversely, radar-based nowcasting models may be a useful tool to guarantee short-term forecasts, through the extrapolation of most recent properties in observed precipitation fields, for lead times ranging from minutes to few hours.

In this study we develop a procedure for merging relevant information from two radar products with different resolutions and scales: (i) high-resolution observations retrieved by an X-band weather radar in a small domain (the metropolitan area of Cagliari, located in Sardinia, Italy), and (ii) the mosaic data provided by the Italian Civil Protection national radar network (the whole region of Sardinia). Specifically, we here adapt some STEPS procedures to merge the large-scale advection from the latter radar network, and the small-scale statistical properties for the former X-band weather radar. We thus combine the corresponding forecasts preserving the higher resolution scale. In details, for each time step we (i) evaluate the power spectra of the two forecasts (ii) merge the two spectra taking the power of the large (small) frequencies from the high (low) resolution data spectrum and (iii) achieve optimal downscaling by reconstructing the high-resolution nowcast from the blend of the two spectra.
Decadal changes in the storage of anthropogenic carbon in the Atlantic Ocean
Authors: Caínzos Verónica , Pérez Fiz F. , Velo Antón , Arumí-Plamas Cristina , Cubas Armas Melania , Santana-Toscano Daniel , Pérez-Hernández M. Dolores , Hernández-Guerra Alonso
Published: March 2021

The Atlantic Meridional Circulation (AMOC) plays a major role in the life cycle of nutrients and chemical species in the ocean, as they are introduced into the ocean by deep water formation and resurface as part of the upwelling. We aim to obtain decadal changes in the latitudinal and vertical distribution of nutrients and carbon species in the Atlantic Ocean, using data from three inverse models carried out for the 1990-99, 2000-09 and 2010-19.  We have used in situ quality-controlled data from GLODAPv2, the neural network CANYON-B for nutrients, and total alkalinity and dissolved inorganic carbon. We then compute the transport of each property, taking into account the results of mass transport balance from the inverse model for each decade. The inverse model has been applied to the whole Atlantic basin with 11 neutral density layers. With these results, we will be able to find out if the CO2 variability arises from changes in circulation or from other processes. On top of that, the availability of several zonal sections for the Atlantic enables the latitudinal division in boxes in which we may find differences in the regional anthropogenic carbon uptake. Our results will allow us to estimate how much anthropogenic carbon is being released or captured within each box, as well as the balance for other variables related to the carbon cycle.
Hurricane ocean wind speeds
Authors: Stoffelen Ad , Marseille Gert-Jan , Ni Weicheng , Mouche Alexis , Polverari Federica , Portabella Marcos , Lin Wenming , Sapp Joe , Chang Paul , Jelenak Zorana
Published: March 2021

How strong does the wind blows in a hurricane proves a question that is difficult to answer, but has far-reaching consequences for satellite meteorology, weather forecasting and hurricane advisories. Moreover, huge year-to-year variability in extremes challenges evidence for changing hurricane climatology in a changing climate. Tropical circulation conditions, such as El Nino and the Madden Julian Oscillation, are associated with the large year-to-year variability and their link to climate change is poorly understood, though of great societal interest. Since hurricanes are sparsely sampled, satellite instruments are in principle very useful to monitor climate change. However, their stability over time in quality and quantity (sampling) needs to be guaranteed. Moreover, to use the longest possible satellite record, satellite instrument intercalibration of the extremes is needed [6]. This applies for a single instrument using a single processor version (calibration, Quality Control, Geophysical Model Function, retrieval) for change detection over a decade typically and the use of overlapping single-instrument/single-processor series for climate analyses. Currently, systematic inconsistencies in the extremes exist, as illustrated within the European Union (EU) Copernicus Climate Change Windstorm Information Service (C3S WISC*) and European organisation for the exploitatrion of Meteorological Satellites (EUMETSAT) C-band High and Extreme-Force Speeds (CHEFS^) projects. Besides for the scatterometers ERS, QuikScat, ASCAT and OSCAT, these instrument series may be extended to passive microwave wind instruments from 1979, if proven reliable at the extremes?

In the EUMETSAT CHEFS project, KNMI, ICM and IFREMER worked with international colleagues to improve the detection of hurricane-force winds. To calibrate the diverse available satellite, airplane and model winds, in-situ wind speed references are needed. Unfortunately, these prove rather inconsistent in the wind speed range of 15 to 25 m/s, casting doubt on the higher winds too. However, dropsondes are used as reference operationally at high and extreme winds in nowcasting and in the European Space Agency (ESA) project MAXSS satellite intercalibration is further investigated based on dropsondes to serve this community. However, from a scientific point of view, we should perhaps put more confidence in the moored buoy references? This would favor accuracy in drag parameterizations and physical modelling and observation of the extremes. This dilemma will be presented to initiate a discussion with the international community gathered at EGU ’21.

* Windstorm Information Service: https://wisc.climate.copernicus.eu/ 

^ C-band High and Extreme-Force Speeds: https://www.eumetsat.int/chefs
Macroevolution and megaclimate: revealing the domains of the Court Jester and biotic equilibration
Authors: Spiridonov Andrej , Lovejoy Shaun
Published: March 2021

The fundamental question of the biodiversity dynamics field is whether global diversity of organisms is driven by multiple random forces resulting in unsteady pattern or is it constrained by sufficiently strong biotic interactions. The first set of hypotheses is combined under the umbrella of the “Court Jester”, reflecting non-steady nature of the process. The latter set of hypotheses is sometimes combined under the header of the “Red Queen”, an epitomization of perpetual change at constant equilibrium diversity level. Based on the Haar fluctuation analyses of the classical Sepkoski database and Paleobiology Database occurrence based biodiversity data, it was revealed that both datasets show that marine animal genus level diversity is characterized by the two regimes.  The first, up to time scales of 30 to 40 Myrs, has a positive scaling exponent implying that fluctuations diverging with time scale i.e. behaviour like the Court Jester that is apparently unstable. The second regime, at longer time scales has a negative fluctuation exponent so that on average anomalies converge, the system is appears stable: a biodiversity regulating Red Queen regime. The smaller scale diverging regime (unstable) is characterized by nearly the same scaling exponent as megaclimate paleotemperatures, suggests a causal connection with diversity.

To investigate this further, we use a new multi-scale Haar fluctuation correlation analysis to quantify the scale by scale correlations.   We found a persistent trend of increasing correlation of macroevolutionary rates with the surface water temperatures with increasing time scales. At the same time, the diversity shows increasingly negative correlations with the temperatures at longer time scales, which suggest that positive largest scale temperature fluctuations although increased biotic turnover had a regulating effect on the global marine animal diversity levels.

Based on the consideration of dominant processes at the longest time scales we propose that the equilibration of biota is a result of continuous geodispersal and consequently mixing and competition of regional biotas, which becomes increasingly more likely on the deca-million-year time scales.

We conclude that the Earth system processes play a significant role in driving both diverging and equilibrating global biodiversity regimes: both Court Jester and Red Queen regimes may operate, with the former dominant up to ≈ 40 Myrs, and the latter at longer time scales.
Evaluation of the Performance of Remotely Sensed Rainfall Datasets for Flood Monitoring in the Transboundary Mono River Catchment, Togo and Benin
Authors: Houngue Rholan , Ogbu Kingsley , Almoradie Adrian , Evers Mariele
Published: March 2021

The variability and changes noted in the climate over the past decades emphasizes the importance of climate information such as precipitation datasets in the management of flood risks in Benin and Togo. The lack of extensive and functional ground observation networks, introduces satellite-based rainfall datasets as a better alternative which needs however to be evaluated beforehand. This study investigated the performance of four satellite and gauge-based rainfall products –Climate Hazards Group Infrared Precipitation with Station data version v2.0 (CHIRPS), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record (PERSIANN), Tropical Applications of Meteorology using Satellite data and ground-based observations (TAMSAT) and the Global Precipitation Climatology Centre full daily data (GPCC) – at gauge point level over the Mono River basin which is stretched over Benin and Togo territories. Three synoptic stations located in Tabligbo, Atakpamé and Sokodé were considered because of the completeness of their time series during the study period 1983-2012. The assessments were conducted at daily, dekadal (10-day period), seasonal and annual scale using both continuous and categorical statistics. Results show poor performances at daily and annual temporal scales while the seasonal cycles were well reproduced with Nash-Sutcliffe efficiency equal or higher than 0.94, and correlation coefficient above 0.9. At Tabligbo, CHIRPS and GPCC showed the best statistical results whereas the performance of PERSIANN and TAMSAT varies with the temporal scale and the station. The probability of rainfall detection (POD) and the capability of reproducing extreme daily maxima indicate GPCC as the best product for flood monitoring purposes at daily scale. However, all assessed products exhibited high POD and low false alarm ratio (FAR) at dekadal scale.
Relative importance of surface mass balance and outlet glacier forcing in ISMIP6 Greenland ice sheet sea-level projections
Authors: Goelzer Heiko ,   The ISMIP6 team
Published: March 2021

The Greenland ice sheet (GrIS) is one of the largest contributors to global mean sea-level rise today and is expected to continue losing mass in the future under increasing Arctic warming. Mass loss in the future is caused by the thinning and retreat of marine-terminating outlet glaciers and to a larger extent by decreasing surface mass balance (SMB) due to increased surface meltwater runoff. In this paper we study the relative importance of changes in SMB and outlet glacier retreat by means of model simulations that have been performed as part of the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6). The effect of the two forcing mechanisms can be separated based on a comparison between full projections and single forcing experiments up to year 2100 for a number of ice sheet models, driving General Circulation Models and two forcing scenarios (RCP2.6 and RCP8.5). We can confirm earlier findings for the high forcing scenario that a compensation between the two processes renders the sea-level contribution from the full experiment lower than the sum of the single forcing experiments.
Jet-driven bow waves as electron accelerators in the magnetosheath: Monte Carlo simulations
Authors: Vuorinen Laura , Vainio Rami , Hietala Heli , Liu Terry Z.
Published: March 2021

Magnetosheath jets are fast flows of plasma frequently observed downstream of the Earth's quasi-parallel shock. Previous observations have shown that these jets can exhibit supermagnetosonic speeds relative to the background flow and develop their own bow waves or shocks. Such jets have been observed to be able to accelerate ions and electrons. In our study, we model electron acceleration by jet-driven bow waves in the magnetosheath using test-particle Monte Carlo simulations that include magnetic mirroring and pitch-angle scattering of magnetic irregularities. We compare the simulation results to spacecraft observations of similar events to understand the acceleration mechanisms at play. Our preliminary results suggest that the energy increase of electrons can be explained by shock drift acceleration at the moving bow wave. Our simulations allow us to estimate the efficiency of acceleration as a function of different jet and magnetosheath parameters. The acceleration introduced by jet-driven bow waves amplifies shock acceleration downstream of the Earth’s bow shock and may also be applicable to other shock environments.
The “Scientific colour map” Initiative: Version 7 and its new additions
Authors: Crameri Fabio , Shephard Grace , Heron Philip
Published: March 2021

Does visualisation hinder scientific progress?

Is visualisation widely misused to tweak data?

Is visualisation intentionally used for social exclusion?

Is visualisation taken seriously by academic leaders?

Using scientifically-derived colour palettes is a big step towards making it obsolete to even ask such brutal questions. Their perceptual uniformity leaves no room to highlight artificial boundaries, or hide real ones. Their perceptual order visually transfers data effortlessly and without delay. Their colour-vision deficient friendly nature leaves no reader left wondering. Their black-and-white readability leaves no printer accused of being not good enough. It is, indeed, the true nature of the data that is displayed to all viewers, in every way.

The “Scientific colour map” initiative (Crameri et al., 2020) provides free, citable colour palettes of all kinds for download for an extensive suite of software programs, a discussion around data types and colouring options, and a handy how-to guide for a professional use of colour combinations. Version 7 of the Scientific colour maps (Crameri, 2020) makes crucial new additions towards fairer and more effective science communication available to the science community.

Crameri, F., G.E. Shephard, and P.J. Heron (2020), The misuse of colour in science communication, Nature Communications, 11, 5444.

Crameri, F. (2020). Scientific colour maps. Zenodo. http://doi.org/10.5281/zenodo.1243862
Microbial responses to drying and rewetting in soils across a European climate transect
Authors: Winterfeldt Sara , Leizeaga Ainara , Rousk Johannes
Published: March 2021

Climate change results in more frequent and intensified drought and rainfall events. The environment exerts a strong control on microbial communities, where drying and rewetting disturbances act as an additional stress that can alter soil processes driving the carbon cycle. Therefore, understanding the environmental control of microbial responses to drying and rewetting events is important to understand the microbial mechanisms controlling the soil C cycle. This study investigated how climate along with soil physiochemical factors affected microbial responses to drying and rewetting. A total of 40 soils across Europe presenting a comprehensive gradient from arctic (N Sweden) to southern Mediterranean (S Greece) climates and wide range of soil properties (SOM: 2-82%, pH: 3.9-7.4, Clay: 8-79%) were exposed to four days of drying followed by rewetting. The microbial growth and respiration responses after rewetting were monitored in high time resolution during 32h. The recovery time of bacterial growth to rates of 50% in undisturbed soil was used as a measure of how resilient microbial communities were to drying and rewetting.

 

The bacterial recovery time after rewetting ranged between 0.6-40h. We found that soils in arid climates had faster bacterial recovery times, suggesting that bacterial communities were more resilient and better adapted to drying and rewetting than those in humid climates, rendering microbial C-use during drying and rewetting more efficient. Furthermore, pH and soil organic matter also had pronounced effects on the resilience of bacterial growth, where acid pH and high soil organic matter resulted in bacterial communities that were slower to recover. In contrast, clay did not have an influence on the resilience of bacterial growth. Our findings suggest that both climate and soil properties are important when determine how soil microbial communities will respond to a drying and rewetting disturbance.
Observation System Simulation Experiments for surface ocean pCO2 reconstructions in the Atlantic Ocean 
Authors: Denvil-Sommer Anna , Gehlen Marion , Vrac Mathieu
Published: March 2021

Global estimates of the ocean carbon sink are released with a yearly frequency as part of the global carbon budget. However, these global estimates hide important spatial and temporal variabilities that can only partly be resolved by direct in situ observations. In this work we explore options for future observational network design combining data streams from various platforms. Our objective is to identify an optimal observational network for surface ocean pCO2 in the Atlantic Ocean and the Atlantic sector of the Southern Ocean. For this purpose, eleven Observation System Simulation Experiments (OSSEs) were performed. Each OSSE is a Feed-Forward Neural Network (FFNN) that is based on different data distributions and provides ocean surface pCO2 for the period 2008-2010 with a 5-day time interval. Based on the geographical and time positions from three observational platforms, volunteering observing ships (VOS), Argo floats and OceanSITES moorings, pseudo-observations were constructed using the outputs from an online-coupled physical-biogeochemical global ocean model with a 0.25º nominal spatial resolution. The aim of this work was to find an optimal spatial distribution of observations to supplement the widely used Surface Ocean CO2 Atlas (SOCAT) and to improve the accuracy of ocean surface pCO2 reconstructions. OSSEs showed that the additional data from mooring stations and an improved coverage of the southern Hemisphere with biogeochemical ARGO floats corresponding to at least 25% of the density of active floats (2008-2010) would significantly improve the pCO2 reconstruction and reduce the bias of derived estimates of sea-air CO2 fluxes by 77%. The use of only SOCAT data results in a correlation coefficient of 0.67 compared to the ocean model output and a 26.08 𝜇atm standard deviation (25.34 𝜇atm for the model reference) over the chosen regions. While the best OSSE has a correlation coefficient of 0.85 and 24.89 𝜇atm for standard deviation. These results are close to the unrealistic benchmark case with total and only Argo float distribution over 2008-2010: 0.87 and 23.79𝜇atm. The reconstructed average pCO2 over the whole region is also close to the model reference, ~370 𝜇atm and ~371 𝜇atm, respectively. The integrated air-sea fluxes fCO2 are about -0.83 Pg/yr (best OSSE) and -0.76 Pg/yr (model reference). 
Abandoned mine after-use as a museum and research site
Authors: Kaljuste Vesta , Väli Erik , Paat Andrus
Published: March 2021

Abstract. Abandoned mines are unique underground facilities due to their unique conditions. Mined-out mine can be used as a museum or scientific and technical research site. Depending on specific mine conditions the after-use purposes can vary. The former Kohtla oil-shale mine, located in the eastern part of Estonia, was closed 10 years before the idea to re-open it as a mining museum. Now old Kohtla mine is used as an underground museum to present for local people and tourists how mining works were carried out in the past (Estonia has 100-year-old experience in oil shale mining) and which methods are still in use. Besides mining, it also shows ventilation and water barrier solutions in the mine. 

 

We present an overview of abandoned mine new challenges to be a safe environment for tourists and as a future research center. The project team had a challenge do design: 

Renovate underground railway, walker’s platform’s, design and establish new roof supports 

New railway platform, stations for tourists, water barriers (3)

Ventilation duct and walls (8), new ventilator;

Closing the workings which are not needed.

Designing was challenging but not the most difficult part of the project. More complicated was to find a competent builder for the underground museum. Renovated and re-ventilated mine was opened in 2012 and today museum is one of the most visited places by the tourists in the eastern part of Estonia, because of its uniqueness. 

 

Besides as a museum, it can be used as a testing site for researchers, because its former infrastructure and facilities have remained. For example, 4 years ago Tallinn University of Technology used the museum area for the backfilling testing because the temperature and other underground conditions were suitable for room-and-pillar mining method backfilling tests. By using backfilling technology, environmental problems such as ground collapses can be avoided and production residues can be reused. As a result of the research, it became clear which ashes of Estonian power plants and the oil industry are suitable for the backfilling technology in terms of physical-mechanical and chemical properties.

 

In addition, we will highlight the best design practices and experiences that have implemented in order to improve old mine everyday working conditions as a museum. These best practices are usually more than the national laws and regulations have requested and they are deeply connected with practical experiences. It meant a lot of collaboration in bringing the best know-how together by different stakeholders. 
Year-long variability of polycyclic aromatic hydrocarbons (PAHs) and their contribution to winter intense pollution events in the urban environment of Athens, Greece 
Authors: Tsiodra Irini , Tavernaraki Kalliopi , Bougiatioti Aikaterini , Grivas Georgios , Apostolaki Maria , Paraskevopoulou Despina , Gogou Alexandra , Parinos Konstantinos , Tsagkaraki Maria , Zarmpas Pavlos , Nenes Athanasios , Mihalopoulos Nikolaos
Published: March 2021

Polycyclic aromatic hydrocarbons (PAHs) are organic pollutants with proven mutagenic and carcinogenic potential that originate from incomplete combustion, and partition to fine particulate matter. Nitro-PAHs & oxy-PAHs are oxidation products of PAHs with increased toxicity compared to their parent members and may reveal useful information about the aging and oxidation processes of PAHs.

In this study, we investigate the seasonal profiles of 31 PAHs and select oxidized forms such as nitro PAHs & quinones in Athens, Greece to understand their sources, levels, toxicity and impacts. PAHs levels were found to be significantly higher during winter, particularly during intense pollution episodes, compared to the other seasons. Chemical markers linked to biomass burning (BB) emissions are found to correlate well with the total amount of PAHs (ΣPAHs) during wintertime, strongly indicating that BB emissions are a significant source of PAHs. Positive Matrix Factorization (PMF) analysis showed that more than 50% of ΣPAHs originate from BB emissions and that a “factor” (composed of a specific mixture of PAHs) characterizes biomass burning emissions – and can potentially be used as a tracer. Analysis of the PMF series suggests that BB aerosol is much more carcinogenic than the effects of gasoline and diesel combustion combined. Finally, the exposure impact during winter is 9 times higher compared with the other seasons.

 Acknowledgements

This work has been funded by the European Research Council, CoG-2016 project PyroTRACH (726165) H2020-EU.1.1. – Excellent. We also acknowledge support by the “PANhellenic infrastructure for Atmospheric Composition and climatE change” (MIS 5021516) implemented under the Action “Reinforcement of the Research and Innovation Infrastructure ”, funded by the Operational Programme “Competitiveness, Entrepreneurship and Innovation” (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund).

 
Estimating the ice thickness of the Müller Ice Cap using an inversion of the shallow ice approximation
Authors: Zinck Ann-Sofie Priergaard , Grinsted Aslak
Published: March 2021

The ice thickness of the Müller Ice Cap, Arctic Canada, is estimated using regression parameters obtained from an inversion of the shallow ice approximation by the use of a single Operation IceBridge flight line in combination with the glacier outline, surface slope, and elevation. The model is compared with an iterative inverse method of estimating the bedrock topography using PISM as a forward model. In both models the surface elevation is given by the Arctic Digital Elevation Model. The root mean squared errors of the ice thickness on the ice cap is 131 m and 139 m for the shallow ice inversion and the PISM model, respectively. Including the outlet glaciers increases the root mean squared errors to 136 m and 396 m, respectively.

The simplicity of the shallow ice inversion model, combined with the good results and the fact that only remote sensing data is needed, means that there is a possibility of applying this model in a global glacier thickness estimate by using the Randolph Glacier Inventory. Most global glacier estimates only provide the volume and not the ice thickness of the glaciers. Hence, global ice thickness models is of great importance in quantifying the potential contribution of sea level rise from the glaciers and ice caps around the globe.
Recirculation of Canadian Basin Deep Water in the Amundsen Sea
Authors: Karam Salar , Heuzé Céline ,   MOSAiC Ocean Team
Published: March 2021

Previous literature has shown that Canadian Basin Deep Water (CBDW) crosses the Lomonosov Ridge into the Amundsen Basin close to the North Pole. This intrusion subsequently flows along the ridge towards Greenland and eventually all the way to the Greenland Sea, but an influence of CBDW in other parts of the Amundsen Basin has also been shown. We detect this deep CBDW intrusion, which is visible as a salinity maximum and oxygen minimum at a depth of about 2000 metres, in hydrographic measurements from MOSAiC and historical data sets. We also use measurements of CFC concentrations for increased robustness, as the high age of CBDW means the water mass is characterised by a CFC minimum. We map the recirculation of this CBDW in the Amundsen Basin and determine its spatial and temporal variability. In particular, we find that CBDW likely flows as a boundary current going eastwards along Gakkel Ridge, and even detect CBDW-like properties on the Nansen Basin side of Gakkel Ridge. As the Arctic Ocean is changing rapidly, understanding its deep circulation and its drivers is becoming increasingly urgent.
Assessment of lead, cadmium, copper and mercury concentration in water of lower Volga-river
Authors: Burtseva Larisa , Pastukhov Boris , Konkova Elizaveta
Published: March 2021

The Volga-river is the main waterway of the European territory of Russia. Its waters flow through densely populated urbanized region included in to the river watershed of 1360 thousand km2, which experience a high level of anthropogenic load. Toxic substances of anthropogenic origin, including heavy metals, wasted out in the environment and enter to the river waters.

Additionally to national monitoring measurements, systematic observations are made by the Yu. A. Izrael Institute of Global Climate and Ecology in the lower Volga River (south of Astrakhan). In this work, we evaluate the level of surface water pollution by lead, cadmium, copper, and mercury for the period 2015-2019.

Surface water sampling was carried out simultaneously at four selected points of significantly remote water bodies of the river Volga catchment area - river Bystraya, river Koklyuy and two branch of the river Buzan (Obzhorov site and Lotus kultuk).The sampling were in the hydrological phases - winter low-water season, high water peak, high water fall, summer low-water season, autumn low-water season. Water samples were preserved with nitric acid and analyzed by atomic absorption spectrometry with electrothermal.

An analysis of the data obtained over a five-year period showed that the average concentrations and standard deviations calculated from the full data set were 1.1 μg/l and 72% for Pb, 3.4 μg/l and 32% for Cu, 5.4 μg /l and 100% for Cd, 1.5 μg / l and 140% for Hg. Variability of concentration is decreases according to the order: Hg> Cd> Pb> Cu, the content of copper and lead in the waters of the lower Volga is most stable in space and time during the period under consideration. The maximum average concentration are characteristic for the river Bystraya - 3.8 μg/l Pb in the winter low-water seasons and 5.7 μg/l Cu in the autumn low-water seasons.

Water pollution of the Volga by Hg and Cd is unstable across the delta region and time. The highest concentration of these trace elements was found in the waters of the river Bystraya. The maximum concentration of cadmium was observed during the winter low-water season, to be around 55 μg/l and mercury - around 28 μg/l , during the high water fall period.

This study was carried out in the framework of the Research Project АААА-А20-120020490070-3 « Development and improvement of methods and technologies for integrated background monitoring and comprehensive assessment of the environmental state and pollution in the Russian Federation including their dynamics (based on the joint results of RosHydroMet’s monitoring networks)».
Coupling the Community Land Model 5.0 with the Parallel Data Assimilation Framework
Authors: Strebel Lukas , Bogena Heye , Vereecken Harry , Hendricks Franssen Harrie-Jan
Published: March 2021

Land surface models are important tools to improve our understanding of interacting ecosystem processes, but their predictions are associated with uncertainties related to model forcings, parameters and process simplifications. As high-quality observations become more and more available, they can be used to constrain the uncertainty of land surface model predictions. In this study, we use data assimilation for the fusion of data into the Community Land Model 5.0 (CLM5). CLM5 simulates a broad variety of important land surface processes including moisture and energy partitioning, surface runoff, subsurface runoff, photosynthesis and carbon and nitrogen storage in vegetation and soil. Here, we focus on water movement in soils and related soil hydraulic parameters and assimilate in-situ soil moisture data into CLM5 to improve the estimate of model states and soil hydraulic parameters. To do this, we have coupled the Parallel Data Assimilation Framework (PDAF) with CLM5. This coupling is based on the online variant of PDAF, i.e., data assimilation occurs during simulation runtime in the main memory and not via input/output files. Online coupling requires modification of the model source code, but we aim to keep the modifications to the CLM5 code minimal so that maintenance of the ongoing CLM5 developments remains straightforward. To this end, our approach reuses the existing CLM5 ensemble mode with only necessary adjustments to connect the PDAF parallel communicators. Furthermore, we developed the coupling in the framework of the Terrestrial System Modeling Platform (TSMP). TSMP is a highly modular modeling system for the fully integrated soil-vegetation-atmosphere system. To illustrate the potential of this coupling, we use the ensemble Kalman Filter to perform simultaneous state and parameter updates in a forest headwater catchment.
Prediction of Petrophysical Properties from Seismic Inversion and Neural Network: A case study
Authors: Garia Siddharth , Pal Arnab Kumar , Ravi Karangat , Nair Archana M
Published: March 2021

Seismic inversion method is widely used to characterize reservoirs and detect zones of interest, i.e., hydrocarbon-bearing zone in the subsurface by transforming seismic reflection data into quantitative subsurface rock properties. The primary aim of seismic inversion is to transform the 3D seismic section/cube into an acoustic impedance (AI) cube. The integration of this elastic attribute, i.e., AI cube with well log data, can thereafter help to establish correlations between AI and different petrophysical properties. The seismic inversion algorithm interpolates and spatially populates data/parameters of wells to the entire seismic section/cube based on the well log information. The case study presented here uses machine learning-neural network based algorithm to extract the different petrophysical properties such as porosity and bulk density from the seismic data of the Upper Assam basin, India. We analyzed three different stratigraphic  units that are established to be producing zones in this basin.

 AI model is generated from the seismic reflection data with the help of colored inversion operator. Subsequently, low-frequency model is generated from the impedance data extracted from the well log information. To compensate for the band limited nature of the seismic data, this low-frequency model is added to the existing acoustic model. Thereafter, a feed-forward neural network (NN) is trained with AI as input and porosity/bulk density as target, validated with NN generated porosity/bulk density with actual porosity/bulk density from well log data. The trained network is thus tested over the entire region of interest to populate these petrophysical properties.

Three seismic zones were identified from the seismic section ranging from 681 to 1333 ms, 1528 to 1575 ms and 1771 to 1814 ms. The range of AI, porosity and bulk density were observed to be 1738 to 6000 (g/cc) * (m/s), 26 to 38% and 1.95 to 2.46 g/cc respectively. Studies conducted by researchers in the same basin yielded porosity results in the range of 10-36%. The changes in acoustic impedance, porosity and bulk density may be attributed to the changes in lithology. NN method was prioritized over other traditional statistical methods due to its ability to model any arbitrary dependency (non-linear relationships between input and target values) and also overfitting can be avoided. Hence, the workflow presented here provides an estimation of reservoir properties and is considered useful in predicting petrophysical properties for reservoir characterization, thus helping to estimate reservoir productivity.
Design and validation of a soil moisture-based wireless sensors network for the smart irrigation of a pear orchard
Authors: Hamouda Fatma , Puig Sirera Àngela , Giusti Stefano , Sbrana Andrea , Tuker Jeff , Bonzi Lorenzo , Iacona Maurizio , Massai Rossano , Rallo Giovanni
Published: March 2021

In this work, we propose to transfer a soil moisture-based wireless sensor network (SM-WSN) to support the reduction of irrigation water consume in the Tuscany region (Italy). The SM-WSN was designed and validated in a commercial pear orchard during two growing seasons (2019-2020) in which the smart irrigation strategy was implemented and applied.

Initially, the micro irrigation system was assessed based on its performance in terms of water distribution uniformity (DU) evaluated with field measurements of emitter flow rates. Then, a zoning analysis was carried out to divide the orchard into homogeneous areas according to the normalized difference vegetation index (NDVI) detected with unmanned aerial vehicle (UAV) and GIS tools. These areas were used to define the topology of the SM-WSN and to investigate how water distribution uniformity can affect the vigour of the trees. A total of 6 “drill & drop” capacitance probes (Sentek Pty Ltd, Stepney, Australia) were installed in the field, after following a simplified laboratory calibration procedure. The hardware and the smartphone-based application, AgriNET, used to download from remote the sensors’ readings were provided by Tuctronics (Walla Walla, Washington, USA).

Assuming that the zoning outcome was only associated with the soil spatial variability, the effect of DU on the vigour of the trees has been identified. Moreover, unlike the ordinary irrigation scheduling applied in the farm, the smart system allowed maintaining the soil water content within a pre-defined optimal range, in which the upper and lower limits corresponded respectively to the soil field capacity and the threshold below which water stress occurs. Based on the smart irrigation management, a water-saving up to 50% of the total water supplied with ordinary scheduling was achieved during both the investigated growing seasons. Moreover, the quality of the productions (i.e °Brix, fruit size and firmness) were in line with the standard required by the farmer. The adoption of the new technology, aiming at identifying the most appropriate irrigation management, has the potential to generate positive economic returns and to reduce the environmental impacts.
Inter-decadal variations of surface winds off Peruvian coast
Authors: Yari Sadegh , Mohrholz Volker
Published: March 2021

The Peruvian upwelling system (PUS) is the most productive marine ecosystem among the Eastern Boundary upwelling Systems (EBUS). The trade wind system drives a nearly continuous upwelling which is subjected to variations on a wide range of times scales. The wind forced upwelling controls crucially the nutrient supply to the euphotic surface layer and thus, the overall productivity of the system.

Using long term data from ERA5 (1979-2019) the wind forcing in the PUS was analyzed to obtain information about long term trends in the mean state and its variability.

Beside the strong annual cycle, the wind forcing is dominated by interannual and a long term interdecadal oscillation.

The interannual fluctuations with a period of 2-5 years are related to the known events of El Niño and La Niña. The wind anomaly shows a good correlation with Oceanic Niño Index (ONI). Interdecadal variation of wind depict a main period of 15-20 years whit negative anomaly values from 1979 to 1996, and positive anomaly values for 1996-2014. These long term variations can be attributed to the Interdecadal Pacific Oscillations (IPO). The spatial distribution of wind stress along the Peruvian coast is not uniform. The highest values are observed in Lima-Marcona area (12º-15.4º S) while it decreases sharply southward and gradually northward. Additionally the coastal upwelling area is modulated locally by the coupling of wind and SST.
Is Venus an analogue for Proterozoic Earth?
Authors: Ghail Richard
Published: March 2021

Venus is our most Earth-like twin, from a geological standpoint, but lacks Earth-like plate tectonics. Its lower mean density implies a smaller core and relatively large mantle, which combined with the inhibited cooling effected by its high surface temperature, suggests that Venus today may be at an earlier evolutionary stage than Earth. Geologically, a global network of rifts and corona chains (e.g. Parga Chasma) indicate subsurface, plate tectonic-like, spreading ridges below a crustal detachment layer, but there are no obvious corresponding subduction zones. Subduction has been inferred locally at a few large corona (e.g. Artemis) but only in relation to specific plumes, not global plate tectonics. Elsewhere there is evidence for numerous large igneous provinces and perhaps an even larger Overturn Upwelling Zones (OUZO) event at Lada Terra. These features suggest a planet in transition from an Archaean-like regime dominated by instability and overturns, towards a more stable plate tectonic regime: i.e. a planet analogous to the early Proterozoic Earth.