bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Multi-scale Approach in Planning and Design of Circular Cities: Mapping the Nexus Between Urban and Natural
Authors: Ristic Trajkovic Jelena , Krstic Verica , Milovanovic Aleksandra
Published: March 2020

The focus of this research is how a multi-scale approach in geospatial information and mapping can contribute to the planning and design of more connected, inclusive, healthy, climate-friendly, and multi-functional circular urban environments. The research addresses the relation between socio-ecological and economic aspects of city development on different spatial levels as a key challenge of European cities. This requires a multidisciplinary and integrative approach to produce effective strategic scenarios of urban development. This methodology is focused on multi-scale analyzes of environmental relationships and provides a flexible framework for improvement of the planning and design of circular cities. Through these advantages, the applied methodology can allow for more flexible identification and improvement of nexus between urban and natural.

One of the basic problems for achieving circularity in urban development is the discontinuous and unplanned urbanization. Such developmental characteristics of cities, as well as the increasing need for nature and biodiversity in cities, necessitated the search for new ecological approaches and principles for their implementation in the process of spatial planning and urban design.  The central research question in the context of sustainable spatial development has become how to ensure multiple balances in-between social, cultural and economic versus ecological systems.

In order to improve the existing circularity and built-natural relations, it is necessary to develop a more complex mapping system which involves planning systems of smaller-scale natural-ecological units integrated into the existing urban structure and connecting them with linear natural-ecological elements. In this sense, the multi-scale methodology is not only reflected in the evaluation of the current situation but also can be used as a tool for testing the variant development opportunities toward circular cities.

The applicability of the developed methodology has been tested within the spatial framework of Belgrade, while the result is a series of critical maps illustrating the nexus between urban and natural in the city.

Acknowledgment: This research was realized as a part of the project “Research and systematization of housing development in Serbia in the context of globalization and European integrations for the purpose of improving housing quality and standards” (TR36034) financed by the Ministry of Education and financed by the Ministry of Education and Science of the Republic of Serbia and COST Action CA17133 - Implementing nature-based solutions for creating a resourceful circular city.
Retrieving tropospheric parameters using predicted multi-GNSS orbit and clock
Authors: Deng Zhiguo , Zus Florian , Balidakis Kyriakos , Jens Wickert , Schuh Harald
Published: March 2020

During the last decade the stability of GNSS clocks has increased dramatically. New generation GNSS satellites are equipped with highly precise and stable clocks and the clock parameters can be predicted with even picoseconds accuracy for several hours. In this work we determined and predicted 90 days precise orbits and clocks of up to 115 satellites from GPS, GLO, GAL, BDS2/3 and QZSS. Based on the calculated and predicted orbit and clock products (SP3) we processed data from about 140 globally distributed stations using PPP in 24 hours static mode. The first 22 hours part uses the calculated satellite products and the last two hours part uses the predicted satellite products. The estimated parameters are daily station coordinates and 30 min tropospheric parameters (ZTD). To validate the last 2-hours of ZTD we generate a reference solution based on 24-hour calculated SP3 products. We also performed a statistical comparison with ECMWF weather model data which yields a root mean square deviation of about 12 mm. This initial comparison indicates that the ZTD estimated from predicted satellite orbit and clocks are sufficiently accurate for time critical meteorological applications.
A normative definition of a Bayesian prior
Authors: Qian Song
Published: March 2020

Applications of the Bayesian statistics require specifying a prior distribution for each unknown parameter to be estimated. The commonly used definition of a Bayesian prior distribution, information about an uncertain parameter, does not provide guidance on how to derive and formulate a prior distribution. In practice, we often use "non-informative" priors or priors based on mathematical convenience. I present a normative definition of the prior based on the shared features of the James-Stein estimator, the empirical Bayes method, and the Bayesian hierarchical model. I use the word "normative" to mean "prescriptive". It also reflects the meaning that the definition can be inconsistent with one another insofar as different types of parameters. I present two case studies where this definition guided me to formulate the modeling processes: one on modeling and predicting cyanobacterial toxin concentration in Lake Erie using chlorophyll-a concentrations (Lake Erie example) and the other on improving the accuracy of calibration-curve-based chemical measurement method (calibration-curve example). The Lake Erie example illustrates temporal exchangeable units, while the calibration-curve example showcases the ubiquity of such exchangeable units.
Activation of the human body exposed to high radon activity
Authors: Golias Viktor
Published: March 2020

Radon is newly considered a risk factor for lung cancer. Traditionally, radon is used as a curative in spa. One way of balneation is radon inhalation in mines (eg Bad Gastein in Austria and Boulder mine in USA), where patients are exposed for several tens of minutes to hours to air activity in the order 10^3 to 10^4 Bq m-3 222Rn. Even higher activities can be found in abandoned uranium mines, often in the order 10^4 to 10^5 Bq m-3 222Rn in the poorly ventilated parts. These underground spaces are often visited by mineral collectors and montanists. In two abandoned uranium mines, the progression of surface beta activity of hair during the stay was monitored and the value and shape of the gamma dose-rate field was measured immediately after mine leaving.

Beta activity increases irregularly, due to the walking between areas with a different radon activity. The highest surface beta activity of hairs was at the end of the stay, with a maximum of 320 Bq cm-2. After leaving the mine, activity decreases exponentially with an effective half-life of about half an hour. Gamma activity was measured after a two-hour stay in an environment with radon activities ranging from 3.7*10^4 to 2.3*10^5 Bq m-3. The gamma field has the shape of a human figure. Especially the lungs and abdominal fat showed increased gamma. The highest gamma dose-rate was measured on hairs, up to 9 µGy h-1. Thus, a combination of surface activation, Rn-product deposition in the lungs, and dissolution of radon in the blood and its redistribution in the body were observed.
Global current systems in Jupiter’s polar magnetosphere
Authors: Kotsiaros Stavros , Connerney John E P , Jørgensen John L , Herceg Matija
Published: March 2020

The Juno spacecraft has been in polar orbit around Jupiter since July 4, 2016 sampling Jupiter's environment from ~1.05 Jovian radii outwards, extending to the distant reaches of the Jovian magnetosphere. Juno’s polar orbit makes it possible to acquire direct observations of the Jovian magnetosphere and auroral emissions above the poles for the first time. We have quantitatively measured magnetic field-aligned (Birkeland) currents which are associated with Jupiter's auroral emissions and have modelled the morphology of the currents based on observations collected along one of Juno’s polar periJove passes. The structure of the field-aligned currents seems to be more complex than expected showing a dynamic filamentation in the azimuthal direction and strong asymmetries between the northern and southern regions. This complexity indicates a non-steady state generation of field-aligned currents possibly with non-linear processes involved. We present a way towards modeling the field-aligned currents more systematically extending the analysis with data from multiple periJove passes. We also show the development of a composite map of field-aligned current regions above the polar aurorae. This map gives us important information on the global structure of the field aligned currents and therefore on how angular momentum is transferred between Jupiter’s atmosphere and magnetosphere.
Hydrological data assimilation using the particle filter in a semi-distributed model MORDOR-SD
Authors: Farouk Imane , Cosme Emmanuel , Metref Sammy , Gailhard Joel , Le-Lay Matthieu
Published: March 2020

A large number of hydrological forecasts are carried out daily by the hydro-meteorologists of the french electricity production agency (EDF). These forecasts are based on a MORDOR hydrological model [Boy, 1996]. Since its development, this model has been noted for its performance [Mathevet, 2005], and a new more advanced version proposing a semi-distributed (or SD) structure improves the quality of the simulations [Garavaglia et al., 2017].

However, many uncertainties such as calibration errors, unavailable observations, and the uncertainties linked to the data used as forcing for the model can have a very significant impact on the quality of the results. Data assimilation is a relevant method for reducing the uncertainties of forcings and then obtain better quality simulations. Previous studies show a gain in the contribution of a variational assimilation to initialize a semi-distributed hydrological model [Lee et al., 2011], but the variational methods are less effective with non-linear behaviors. Therefore the ensemble methods are more widely adopted, as the ensemble Kalman filter (or EnKF) assimilation method which can be found in various studies ([Han et al., 2012], [Clark et al., 2008], [Xie and Zhang, 2010], [Slater and Clark, 2006], [Chen et al., 2011], [Alvarez-Garreton et al., 2015]).

As part of our study, a particle filter has been implemented as an assimilation scheme in the semi-distributed hydrological model MORDOR-SD. Several types of observations, such as the flow at the outlet of the watershed or the snow stock, were used in this assimilation system. Some sensitivities experiments on the various parameters specific to the system as well as on the choice of the observations to be taken into account were carried out. This study will show the benefits obtained from the assimilation of in situ data on the quality of the simulations as well as on the forecasts. Performed in many different areas (the study covers several watersheds), the analysis of observation errors and the construction of a specific observation error model brings an additional benefit in the quality of the results.

 
The estimate and scaling of mass and energy fluxes from three different ecosystems in the Trentino Alto Adige/South Tyrol (Italy) region: Preliminary results from the Wheat Project.
Authors: Falocchi Marco , Giovannini Lorenzo , Belelli Marchesini Luca , Gianelle Damiano , Montagnani Leonardo , Zardi Dino
Published: March 2020

The estimate and parameterization of mass and energy fluxes exchanged in the atmospheric surface-layer, between the biosphere and the atmosphere, plays a key role in many disciplines, e.g. meteorology and atmospheric sciences, ecology and precision agriculture.

In mountain environments, crests lines tend to decouple the atmospheric processes close to the ground from those in the upper layers and deeply affect the penetration of solar radiation on the floors and the sidewalls of valleys. The consequent differential heating of the surface allows the onset of many local phenomena, such as thermally-driven flows and temperature inversions, with impacts on the regime of the exchanges. Indeed, the low-wind conditions, the wind interaction with landforms and the atmospheric stability control the turbulence and the development of sub-meso motions, i.e. those phenomena responsible for the diffusion and transport of substances, respectively.

The Wheat Project is a 2-year-long project, started on November 2018 and funded by the CARITRO Foundation (“Cassa di Risparmio di Trento e Rovereto”, Italy), which aims at investigating the basic mechanisms responsible for biosphere-atmosphere exchanges in mountain areas, in order to improve their estimate and scaling.

Three datasets collected by long-term research infrastructures and composed of both biochemical and atmospheric quantities measured over different ecosystems were selected in the Trentino Alto Adige/South Tirol region (Italy). Data were measured at the research facility managed by the Free University of Bolzano/Bozen at Caldaro, over an apple orchard (220 m ASL, available period 2010-2018), and at the research facilities managed by the Fondazione Edmund Mach at Monte Lavarone, over a forest (1349 m ASL, available period 2000-2018) and at Viote del Monte Bondone, over an Alpine grassland (1553 m ASL, available period 2002-2018).

This contribution focuses on the pre-processing procedure adopted to identify representative periods for the analyses and on the methods implemented to retrieve turbulence parameters. In particular, the identification of the characteristic time-scales of small-scale turbulence is carried out through an application of the anisotropic analysis of turbulence, whereas the separation of the turbulence signal from low-frequency fluctuations is performed by implementing a recursive digital filter. Finally, some preliminary results regarding the estimate and the scaling of the turbulent fluxes of momentum, sensible heat, moisture and carbon dioxide are presented.
A 4-D reconstruction of post debris-flow sediment dynamic inferred from multi-temporal terrestrial laser scanning and photogrammetry (Roßbichelgraben, Germany)
Authors: Dietrich Andreas , Keilig Klaus-Peter , Stammberger Verena , Krautblatter Michael
Published: March 2020

Debris flows are destructive mass movements in steep alpine torrents. Due to their high magnitudes and impact pressures economic goods and human lives are threatened in inhabited areas. The amount of entrained material depends largely on the mobilisable loose debris available for transport, which in turn controls debris-flow mobility and runout. However, still very limited data exists regarding rates and controls of sediment recharge in debris-flow channels.

In June 2015 an extraordinary rainfall event triggered a debris flow in the Roßbichelgraben torrent in southern Germany. Twelve terrestrial laser scan campaigns (> 450 scans positions) and nine temporally synchronised UAV surveys were carried out between June 2015 and September 2019. Both TLS and SfM-based photogrammetry reveal the temporal, spatial and seasonal sediment dynamic in the channel. A nearby meteorological station recorded the rainfall intensity in 10 min intervals. The results show that both terrestrial laser scanning and SfM-based photogrammetry provide equivalent erosion and deposition volumes (difference < 5%). Between June 2015 and September 2019 the channel was refilled with material of adjacent slopes and the above lying catchment (≈ 1.2 m³/d), whereby a higher activity was observed in summer than in winter. In addition, the activity decreased with elapsed time since the debris-flow event, as most over-steepened river banks failed shortly after the event and stabilised over time. Short, intense rainstorm events best explain the sediment dynamic in the channel (R² up to 0.9).

The results contribute to better understand the sediment dynamic in highly active debris-flow channels and allow for a more reliable estimation of potential debris-flow volumes.
Can daily GRACE gravity field models be used to evaluate short-term hydro-meteorological signals over the continents?
Authors: Eicker Annette , Jensen Laura , Wöhnke Viviana , Kvas Andreas , Dobslaw Henryk , Mayer-Gürr Torsten , Dill Robert
Published: March 2020

Over the recent years, the computation of temporally high-resolution (daily) GRACE gravity field solutions has advanced as an alternative to the processing of monthly models. In this presentation we will show that recent processing improvements incorporated in the latest version of daily gravity field models (ITSG-Grace2018) now allow for the investigation of water flux signals on the continents down to time scales of a few days.

Time variations in terrestrial water storage derived from GRACE can be related to atmospheric net-fluxes of precipitation (P), evapotranspiration (E) and lateral runoff (R) via the terrestrial water balance equation, which makes GRACE a new and completely independent data set for constraining hydro-meteorological observations and the output of atmospheric reanalyses.

In our study, band-pass filtered water fluxes are derived from the daily GRACE water storage time series by first applying a numerical differentiation filter and subsequent high-pass filtering to isolate fluxes at periods between 5 and 30 days. We can show that on these time scales GRACE is able to identify quality differences between different global reanalyses, e.g. the improvements in the latest reanalysis ERA5 of the European Centre for Medium-Range Weather Forecasts (ECWMF) over its direct predecessor ERA-Interim.

We can further demonstrate that only the very recent progress in GRACE data processing has enabled the use of daily GRACE time series for such an evaluation of high-frequency atmospheric fluxes. The accuracy of the previous daily GRACE time series ITSG-Grace2016 would not have been sufficient to carry out such an assessment.
How to evaluate rainfall estimation performance? - A discussion of metrics, thresholds and aggregations for one year of country-wide CML rainfall estimation
Authors: Graf Maximilian , Chwala Christian , Polz Julius , Kunstmann Harald
Published: March 2020

In recent years, so-called opportunistic sensors for measuring rainfall, are attracting more notice due to their broad availability and low financial effort for the scientific community. These sensors are existing devices or infrastructure, which were not intentionally built to measure rainfall, but can deliver rainfall information. One example of such an opportunistic measurement system are Commercial Microwave Links (CMLs), which provide part of the backbone of modern mobile communication. CMLs can deliver path-averaged rainfall information through the relation between rainfall and attenuation along their paths. Before such an opportunistic data source can be used, either as an individual or a merged data product, its performance compared to other rainfall products must be evaluated.

We discuss the selection of performance metrics, spatial and temporal aggregation and rainfall thresholds for the comparison between a German-wide CML network and a gauge-adjusted radar product provided by the German Weather Service. The CML data set consists of nearly 4000 CMLs with minutely readings from which we will present a year of data. 

First, we show the influence of the temporal aggregation on the comparability. With higher resolution, the impact due to small temporal deviations increases. Second, CMLs represent path-averaged rainfall information, while the radar product is gridded. We discuss the choice whether the comparison should be performed on the point, line or grid scale. This choice depends on the desired future applications which already should be considered when selection evaluation tools. Third, the decision to exclude rain rates below a certain threshold or the calculation of performance metrics for certain intervals gives us a more detailed insight in the behavior of both rainfall data sets.
Development of the method for detecting natural frequencies of blocks in seismic noise before small seismic events
Authors: Besedina Alina , Pavlov Dmitry
Published: March 2020

Previous studies of microseismic noise before earthquakes in seismically active regions showed the possibility of detecting the preparation processes of seismic events. This effect manifests itself as decrease of the frequency of natural oscillations before earthquakes. In this work, the method for detecting the natural frequencies of blocks in seismic noise is adapted to a lower hierarchical level. Using known empirical relations for faults with a characteristic length of less than 500-1000 m, the characteristic natural oscillation frequencies that can be used to diagnose a fault zone are estimated. For small seismic events with magnitudes Mw from -2 to -1, we calculated the expected frequencies of natural vibrations of 350-1100 Hz, and for events with Mw from 0 to 1,  - below 35 Hz. For analysis, we used the recording data of high-frequency accelerometers at a depth of 300 m from the free surface in the area of the city of Gubkin (Russia) within iron ore deposits. Before small events with an amplitude of more than 0.01 m/s2. The intervals of decrease in the spectral centroid in the range of 20-1200 Hz were identified. The minimum values of the spectral centroid obtained on the basis of experimental data are generally in a good agreement with theoretical estimates. This work was supported by RFBR (project # 18-05-00923).
A 1,600 year record of paleoseasonality from the neotropics of Central America and its implications for rainfall predictability in agricultural societies
Authors: Prufer Keith , Breitenbach Sebastian , Baldini James , Braun Tobias , Ray Erin , Baldini Lisa , Polyak Victor , Lechleitner Franziska , Marwan Norbert , Kennett Douglas , Asmerom Yemane
Published: March 2020

For millions of people living in the humid neotropics seasonally predictable rainfall is crucial for agricultural success and food security.  Understanding long-term stability and volatility of seasonal rainfall distributions should be of concern to researchers and policy makers. However, reconstructions of paleorainfall seasonality in the neotropics have been constrained by a lack of precisely dated and sub-annually resolved records. We present a 1,600-year rainfall paleoseasonality reconstruction from speleothem sample Yok G, from Yok Balum Cave located in southern Belize, Central America. Yok G grew continuously from 400 C.E. to 2,006 C.E. and its age is constrained by 52 U-series dates with a mean error of ~7 years. The isotope record consists of 7,151 δ18O and δ13C measurements at ~0.22-year resolution allowing us to detect the presence and amplitude of annual wet-dry cycles. In Belize rainfall distribution and seasonality controls are currently dominated by the annual migration of the intertropical convergence zone (ITCZ) with marked meridional contrast.  The Yok G record suggest distinct changes in seasonality at multi-centennial intervals.  The earliest portion of the record (400-~850 C.E.) shows little intra-annual seasonal variation, the period from ~850-1400 C.E. has highly variable annual oscillations and periods of low seasonality, while the period from 1,400-2,006 C.E. shows well developed seasonal signals.  Element ratios (Mg/Ca, Sr/Ca, and U/Ca) are used to assess Prior Carbonate Precipitation in the epikarst system.  We review these changes and the isotopic record from Yok G and discuss tools for interpreting the stability and volatility in seasonal rainfall distributions and possible implications for past and modern agricultural societies. 
Assessment of slope deposits depth at regional scale by means of morphometric clustering and multi-linear regression: a comparison
Authors: Disperati Leonardo , D'Addario Enrico , Papasidero Michele Pio , Pignatiello Marco , Marzini Lorenzo , Amaddii Michele , Broda Nazariy
Published: March 2020

Apart high elevation and arid regions, bedrock is generally covered by unconsolidated materials that result from recent or actual bedrock weathering and fracturing, consequent transport along the hillslope mainly by un-channelized flux or gravity-dominated processes and deposition. These slope deposits (SD) are largely affected by shallow landslides triggered during intense rainfall events, hence mapping SD spatial distribution and properties is a challenging task to perform accurate regionalized analysis of landslide hazard.

Nevertheless, geological and geomorphological maps typically represent the spatial distribution of SD following a 0/1 approach, instead of attempting to describe, in a more realistic perspective, the spatial variation of SD depth, even though this latter is a fundamental input parameter for landslide hazard estimation by physically based models.

In this work we present two different approaches to assess SD depth at regional scale, coupling field SD depth measurements, statistical analysis and then topographic-based regionalization: unsupervised clustering and multilinear regression analysis. Geo-environmental variables such as geology, land use and morphometric parameters, have been considered. The unsupervised clustering analysis has been based on some morphometric variables (eg. flow accumulation, slope and hillslope curvatures), derived from a digital elevation model with cell size of 10 m. These variables allowed us to extract, for homogeneous regions obtained by considering bedrock lithology, a set of morphometric units where the distribution of SD depth was assessed. The same variables were processed in the multilinear regression analysis in order to obtain equations estimating the spatial distribution of SD depth. The results of this work were then compared each other, as well as to the outputs obtained by implementing other methods of SD depth estimation known in the literature. Finally, the proposed methods were applied to evaluate SD depth in a test area, where field survey measurements were used as a check to assess the prediction capability. The results are analyzed and discussed in order to identify best solutions to evaluate and represent SD depth at regional scale.
Large Eddy Simulations of the Arctic atmospheric boundary layer around the MOSAiC drift track
Authors: Littmann Daniela , Dorn Wolfgang , Bresson Hélène , Maturilli Marion , Rex Markus
Published: March 2020

The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) is the largest one-year-long research expedition within the central Arctic and has started in September 2019 to gather comprehensive climate data from an almost unreachable region. The gathered observational data in combination with concurrent high-resolution modeling provide new insights that play a key role for the improvement of our understanding of the interaction processes between the atmosphere, ocean, and sea ice and eventually global climate change. The present study focuses on the influence of the surface conditions on the atmospheric boundary layer by applying the large eddy simulation model configuration of the icosahedral non-hydrostatic model (ICON-LES). ICON-LES is used here with a grid spacing between 50 m and 800 m and set up to a domain with radii of 10 km to 100 km around the MOSAiC drift track. The model is driven by output data from weather forecast simulations for selected stormy and rather calm days. Results of simulations with various spatial horizontal resolutions and with different surface conditions such as ice fraction, ice thickness, snow cover will be compared and evaluated against observational data from MOSAiC.
On the added value of improving the spatial representation and seasonal variations of vegetation cover in land surface models for simulated land surface temperature
Authors: Nogueira Miguel , Albergel Clément , Boussetta Souhail , Johanssen Frederico , Dutra Emanuel
Published: March 2020

Earth observations were used to evaluate and improve the representation of Land Surface Temperature (LST) and vegetation coverage over Iberia in two state-of-the-art land surface models - the European Center for Medium Range Weather Forecasting (ECMWF) Hydrology Tiled ECMWF Scheme for Surface Exchanges over Land (HTESSEL) and the Méteo-France Interaction between Soil Biosphere and Atmosphere model (ISBA) within the SURface EXternalisée modelling platform (SURFEX-ISBA) for the 2004-2015 period.

The results show that the daily maximum LST simulated by HTESSEL over Iberia is affected by a large cold bias during summer months when compared against the Satellite Application Facility Land Surface Analysis (LSA-SAF), reaching magnitude larger than 10ºC over wide portions of central and southwestern Iberia. This error is shown to be tightly linked to a misrepresentation of the vegetation cover.  In contrast, SURFEX simulations did not had such a cold bias. This was due to the better representation of vegetation coverage in SURFEX, which uses an updated land cover dataset (ECOCLIMAP II) and an interactive vegetation evolution, representing seasonality.

The representation of vegetation over Iberia in HTESSEL was improved by combining information from the European Space Agency Climate Change Initiative (ESA-CCI) land cover dataset with the Copernicus Global Land Service (CGLS) Leaf Area Index (LAI) and fraction of vegetation coverage (FCOVER). The proposed improvement vegetation includes a clumping approach to introduce seasonality to the vegetation coverage. The results show significant added value, removing the daily maximum LST summer cold bias completely while never reducing the accuracy over all seasons and hours of the day.

This work has important implications: First, LST is a key variable in surface-atmosphere energy and water exchanges and, thus, its accurate representation in earth system models is very important. Second, HTESSEL is the land surface model employed by ECMWF in the production of their weather forecasts and reanalysis, hence systematic errors are propagated into these products. Indeed, we show that the summer daily maximum LST cold bias over Iberia in HTESSEL is present in the widely used ECMWF fifth generation reanalysis (ERA5) and fourth generation reanalysis (ERA-Interim).  Finally, our results provide hints into the interaction between vegetation land-atmosphere exchanges, highlight the consistent relevance of the vegetation cover and seasonality in representing land surface temperature in both models, and how earth observations play a critical role for constraining and improving weather and climate simulations.
Basin-scale granular ice dynamics modelling
Authors: Lehtiranta Jonni
Published: March 2020

Current operational sea ice models solve primitive equations on a grid and treat sea ice as a continuum with smoothly varying properties. This is the same method that is used in ocean models. The continuum assumption is unrealistic for sea ice which consists of separate rigid ice floes. The assumption works best for length scales much larger than typical floe size, and worst for very small length scales.

Winter shipping in finnish ports depends on timely sea ice information on the Baltic Sea. Due to climate change, the yearly ice covered area and thermodynamic ice growth are decreasing. However, sea ice is also becoming more mobile and dynamic, especially in the Bay of Bothnia which lies in the north end of the Baltic Sea.

A particle-based granular approach is more realistic in the length scales of individual ice floes. Such models have been developed (eg. by Mark Hopkins and Agnieszka Herman) and used successfully in limited scales, such as fjords. For larger horizontal scales, they have been computationally too expensive. Using modern GPU acceleration techniques, discrete element simulation of sea ice is becoming possible in the scale required for Baltic sea basins.

This work presents an ongoing project for building a granular sea ice model for forecasting ice dynamics. This includes ice movement and deformation and describes ridge and lead formation and similar phenomena. Existing accelerated solvers are examined, and the most suitable is adapted for Baltic sea ice and applied for the Bay of Bothnia.
The fate of river-borne floating marine litter in the coastal sea: a case study of flooding discharge from numerous small rivers in the northeastern part of the Black Sea
Authors: Korshenko Evgeniya , Zhurbas Victor , Osadchiev Alexander , Belyakova Pelagiya
Published: March 2020

This study is focused on delivery and transport of floating marine litter, which is carried by river discharge to coastal sea. This floating matter initially is contained in river plumes and its transport is governed by river plume dynamics. Despite the great importance of understanding the fate of floating marine litter (including plastic litter) in the sea, many aspects of its transport and accumulation remain unstudied. In this study we consider a large flood which happened in the northeastern part of the Black Sea in October 2018. A high resolution circulation model with a non-uniform horizontal grid (the grid bin length is decreased up to 200 m in a local area of interest) is applied to simulate transport of floating matter brought into the sea by overflowing rivers. The floating matter transport is modelled by horizontal advection of Lagrangian particles seeded in the mouths of main rivers of the study region in proportion to the actual river runoff. The particles that originated from different river mouths merge together on a horizontal velocity convergence line. These areas of accumulated marine litter remain stable during several days and are transported off the river mouths by a quasi-geostrophic alongshore current. However, some of the particles are trapped in the surf zone and form irregular contamination of the shoreline depending on local circulation features controlled by bottom topography and local wind forcing.  
Evaluation of combined radiocarbon and carbon stable isotope data of PM2.5 carbonaceous aerosol in Debrecen, Hungary
Authors: Major István , Furu Enikő , Varga Tamás , Horváth Anikó , Futó István , Gyökös Brigitta , Kertész Zsófia , Jull AJ Timothy , Molnár Mihály
Published: March 2020

Comprehensive atmospheric studies have demonstrated that carbonaceous aerosol is one of the main components of atmospheric particulate matter over Europe. Despite its significant role in atmospheric processes, the characteristic of carbonaceous particle sources and the contributions from modern and fossil sources in the Pannonian Basin are still less known. Using radiocarbon as a tracer, the ratio of modern (biological aerosol, wood burning etc.) and fossil (coal or oil burning, transportation) sources for an aerosol sample can unambiguously be determined but identification of exact sources is not possible. Considering other isotopic techniques, carbon stable isotope results can provide us such supplementary information that can be used in separating different large source clusters (e.g. burning of C3 type wood, coal burning or transportation). Different aerosol sources have well defined carbon stable isotope ranges, which can be used in source apportionment models. Nevertheless, these ranges often overlap each other, making the accurate source identification rather difficult. Combined radiocarbon and carbon stable isotope measurements can however help us to differentiate more precisely numerous modern or fossil sources.

In our study, the isotopic composition of carbon in the PM2.5 atmospheric aerosol collected on weekly basis in Debrecen, Hungary was investigated. In doing so, the organic and elemental carbon content, the specific 14C content and the δ13C values of total carbon were measured using a Sunset OC/EC analyser, an accelerator mass spectrometer (AMS) and an EA/IRMS instrument, respectively. Based on our three-year long carbon stable isotope data of carbonaceous aerosol, relatively enriched δ13C results can be observed in each wintertime period, which are supposed by other authors to be related to the effect of coal combustion (mainly in heavily industrialised areas). Contrarily, radiocarbon measurements imply the dominance of modern sources for the same wintertime periods when the biological activity of vegetation is moderate. Consequently, according to our assumption, these values are caused by modern sources having more positive δ13C value such as biomass burning of residences. In contrast to single stable isotope or radiocarbon measurements our study sheds light on the importance of combined carbon isotopic investigations. The research was supported by the European Union and the State of Hungary, co-ﬁnanced by the European Regional Development Fund in the project of GINOP-2.3.2-15-2016-00009 ‘ICER’
Ensemble-Based Data Assimilation for Wind Forecasting – Application to Wind Farm
Authors: Fan Yang-Ming
Published: March 2020

The purpose of this study is to develop an ensemble-based data assimilation method to accurately predict wind speed in wind farm and provide it for the use of wind energy intelligent forecasting platform. As Taiwan government aimed to increase the share of renewable energy generation to 20% by 2025, among them, the uncertain wind energy output will cause electricity company has to reserve a considerable reserve capacity when dispatching power, and it is usually high cost natural gas power generation. In view of this, we will develop wind energy intelligent forecasting platform with an error of 10% within 72 hours and expect to save hundred millions of dollars of unnecessary natural gas generators investment. Once the wind energy can be predicted more accurately, the electricity company can fully utilize the robustness and economy of smart grid supply. Therefore, the mastery of the change of wind speed is one of the key factors that can reduce the minimum error of wind energy intelligent forecasting.

There are many uncertainties in the numerical meteorological models, including errors in the initial conditions or defects in the model, which may affect the accuracy of the prediction. Since the deterministic prediction cannot fully grasp the uncertainty in the prediction process, so it is difficult to obtain all possible wind field changes. The development of ensemble-based data assimilation prediction is to make up for the weakness of deterministic prediction. With the prediction of 20 wind fields as ensemble members, it is expected to include the uncertainty of prediction, quantify the uncertainty, and integrate the wind speed observations of wind farms as well to provide the optimal prediction of wind speed for the next 72 hours. The results show that the prediction error of wind speed within 72 hours is 6% under different weather conditions (excluding typhoons), which proves that the accuracy of wind speed prediction by combining data assimilation technology and ensemble approach is better.
Small scale CO2 fluxes in a rainfed maize field under N fertilization
Authors: Gelybó Györgyi , Deli Réka , Dencső Márton , Kósa Bernadett , Mateika Viktória , Tóth Márton , Ujj Emese , Árendás Tamás , Fodor Nándor , Bayoumi Hosam
Published: March 2020

Carbon-dioxide (CO2) fluxes in the soil-plant-atmosphere system contain bidirectional material transport with organic and inorganic sources and sinks, and various pathways. Proportion of irrigated fields in the total area of Hungarian arable lands is low, and incase of a rainfed field water and CO2 fluxes are only driven by meteorological factors. In this study we focused on maize under different fertilization treatments to see the plot scale variability of CO2 fluxes and connected parameters.

The site is a multifactorial sowing time-fertilizer-maize variety field experiment near Martonvásár. Two treatment plots were selected for the measurements with contrasting 60 kg N ha-1 and 180 kg N ha-1 fertilizer treatments and no other factors were considered in the present study. We performed synchronized observations of (i) CO2 fluxes: soil respiration (Rs; EGM-5 gas analyser + SRC-1 chamber, PPSystems); leaf scale photosynthesis (A; CIRAS-3 portable photosynthesis system, PPSystems)), (ii) soil temperature and soil water content, (iii) plant parameters: root growth (CI-600, CID-Bioscience), plant height, leaf area index (Accupar LP-80 ceptometer, Li-Cor). Data on the above parameters comprise several spatial replicates to explore spatial heterogeneity in case of a maize field managed in accordance with the typical Hungarian practice. The average applied N amount in the country is around 100-105 kg ha-1.

Field measurements for CO2 fluxes and biotic and abiotic drivers were performed six times in the vegetation period to establish relationship among them. Data were analyzed to optimize the labour intensive protocol for this experimental setup. Photosynthesis varied within the vertical canopy as reflected by measurements on five leaves per plant. Soil respiration was more dependent temporally on soil water availability than on temperature.
Weathering and conservation of tuff stone
Authors: Stuff Maria , Rübner Katrin , Prinz Carsten , Rische Nicole , Chronz Matthias , Kühne Hans-Carsten
Published: March 2020

Tuff stone, a porous pyroclastic rock, is a light and soft material. Hence, tuff is easy to handle and to transport. It is used as construction material in numerous historical buildings. Due to its high water absorption and retention potential, heterogeneous pore structure, and clay mineral content, tuff is highly sensitive to weathering by moisture expansion and salt crystallization [1; 2]. The search for a protective agent for tuff stone has been subject to scientific studies for several decades. Yet, due to the high variability and heterogeneity of tuff stone, no generally applicable means to protect tuff against weathering has been found to date. Instead, case specific solutions are developed to preserve historical buildings. Often it is necessary to remove weathered parts of the stone or exchange whole tuff ashlars to ensure the stability of the construction. Since tuff is a limited resource, it is crucial to find suitable protective agents that prolong the life-cycle of tuff stone to preserve historical buildings

To favourably influence water absorption, effective porosity, and the pore structure of tuff stone, a thorough impregnation of the stone with the protective agent is desirable. This can be achieved by the application of silica sol products, which are dispersions of colloidal amorphous silicon dioxide particles. The small particle sizes (between 10 and 100 nm) facilitate a high penetration depth. Despite of the promising results of several studies, colloidal silicas are rarely used as protective agents for tuff stone in the restauration practice [3; 4]. This may be due to the lack of long-term experiences with these materials. Furthermore, the performance of protective agents is closely related to the pore structure and chemical and mineralogical composition of the rock [5; 6]. To understand these interactions, further research is needed.

The aim of a current research project is to study the application of colloidal silica as protective agent for Weiberner tuff. In first tests, penetration depth and changes in the pore structure are analyzed. Furthermore, the influence of the treatment on the hygric and mechanical properties and on the durability of the stone is studied. The new data will contribute to a better understanding of tuff stone deterioration and conservation.

 

[1] Wedekind et al. (2013) Environ. Earth Sci. 69. [2] Pötzl et al. (2018) Environ. Earth Sci. 77. [3] Iucolano et al. (2019) Contr. Build. Mater. 202. [4] Zornoza-Indart & Lopez-Arce (2016) J. Cult. Herit. 18. [5] Török et al. (2007) Geol. Soc. London, Spec. Publ. 271. [6] Stück et al. (2008) Environ. Geol. 56.
Electromagnetic radiation from upper-hybrid wave turbulence driven by electron beams in solar plasmas
Authors: Gauthier Gaetan , Krafft Catherine , Savoini Philippe
Published: March 2020

Solar radio bursts of Type III are believed to result from a sequence of physical processes ultimately leading to electromagnetic wave emissions near the electron plasma frequency ωp and its harmonic 2ωp. The radiation bursts are due to energetic electron beams accelerated during solar ﬂares. When propagating in the solar corona and the interplanetary wind, these ﬂuxes excite Langmuir and upper-hybrid wave turbulence, which can be further transformed into electromagnetic radiation near the frequencies ωp and 2ωp.

It is believed that, in a homogeneous plasma, Langmuir turbulence evolves due to three-wave interaction processes, such as the fusion of Langmuir waves L with sound waves S leading to the formation of electromagnetic waves Tωp at ωp or the decay of L-waves into S-waves and Tωp-waves. On the other hand, the electromagnetic waves radiated at 2ωp should arise from the coalescence L + L’ --> T2ωp of Langmuir waves L generated by the beam with Langmuir waves L’ coming from the electrostatic decay L --> L’ +  S.

Large-scale 2D3V Particle-In-Cell simulations have been performed with the fully kinetic code Smilei [Derouillat et al., 2018], using parameters typical of Type III solar radio busts. The excitation of upper-hybrid wave turbulence by energetic electron beams propagating in magnetized plasmas leads ultimately to electromagnetic emissions near the fundamental and the harmonic plasma frequencies.

Derouillat et al. , Comput. Phys. Commun., 222, 351, 2017.
Investigation of the relationship between sensitivity level of the sources and the internal reliability value of VLBI observations during CONT14
Authors: Kurec Nehbit Pakize , Heinkelmann Robert , Schuh Harald , Konak Haluk
Published: March 2020

The quality of geodetic networks can be determined with the sensitivity and the internal reliability magnitudes when the mathematical model established for the network adjustment is questioned. Internal reliability is used for controlling an observation with the help of the other observations in the network and describes the magnitude of the undetectable gross errors by using hypothesis testing. The sensitivity level is explained as the minimum value of the undetectable gross error in the adjusted coordinate differences. In VLBI the observed sources are of major importance for the quality of the observations.  In this study, it is investigated how the sensitivity levels of the sources impact the internal reliability of the observations during the continuous VLBI campaign CONT14. It is aimed to detect the poor sources and their effects statistically in the VLBI data analysis. If the sources having worst sensitivity value such as 0506-612, 3C454.3, NRAO150, and 3C345  have been excluded, the internal reliability values of the observations get better. For the rest of the sources the sensitivity distributions have been obtained as better. It can be concluded that the source structure might be significant for the quality of the observations.
Ensemble prediction with OpenIFS
Authors: Ollinaho Pirkka
Published: March 2020

Probabilistic forecasts provide information on how predictions of the atmospheric evolution may differ from the best guess solution provided by a deterministic forecast. Ensemble prediction systems generate this information through assessing uncertainties in both the model initial state and the model itself. In order to open up ensemble prediction research for a wider research community, we have recreated all 50+1 operational ECMWF ensemble initial states for OpenIFS. The data set covers one year (December 2016 to November 2017) twice a day. A range of model resolutions are provided to cover different research needs (TL159, TL399 and TL639). The probabilistic skill of OpenIFS ensembles using these initial states is showcased. A case study of typhoon Damrey, which severely affected Vietnam in 2017, will also be presented.