bluuebunny/crossref_metadata_2025 huggingface dataset:
Particle-Resolved Direct Numerical Simulations of Clay Particles in the Absence of Gravity.
Authors: Kleischmann Fabian , Luzzatto-Fegiz Paolo , Rommelfanger Nick , Meiburg Eckart , Vowinckel Bernhard
Published: March 2021

Flocculation processes of clay particles are usually influenced by settling effects due to gravity. This inhibits the investigation of the effects of cohesive forces in isolation and limits our understanding of flocculation processes over long time scales that are more common in aquatic environments. To address this issue, particle-resolved Direct Numerical Simulations (pr-DNS) are conducted to simulate the flocculation processes of a preceding campaign of microgravity experiments that have been performed onboard the International Space Station (ISS). The experiments with clay suspensions of kaolin (8 ppt) in saline water (35 PSU) have been examined in the absence of gravity over a time period of more than 100 days by taking pictures of the suspension at regular time intervals. The results of the image analysis are used to validate the numerical computation of clay aggregate growth over time. The simulations are based on a numerical cohesion model which includes the fluid-particle interaction via the Immersed Boundary Method (IBM) by geometrically resolving the flow field around the suspended particles. To this end, monodisperse spherical primary particles were randomly placed in a triple-periodic box and exposed to an oscillatory flow. This oscillation is used to mimic the jitering motion of the ISS, which may be caused by onboard instruments as well as the drive-line technology. In this talk, we will present the results of these simulations and link them to the observations provided by the microgravity experimtents.
Integration of ambient noise and ERT data to investigate the structure of the Yang Jia Gou rock avalanche deposits (Sichuan - China)
Authors: Capone Paola , Del Gaudio Vincenzo , Wasowski Janusz , Hu Wei , Venisti Nicola , Li Yan
Published: March 2021

On 12 May 2008, the mountainous area of Longmenshan, which separates the Tibetan Plateau from the Sichuan Basin, was hit by the 8.0 Ms Wenchuan earthquake which triggered about 200,000 landslides, some of which caused river damming with the formation of temporary lakes. Failures of the landslide dams can induce severe flooding downstream, therefore, it is important to study their structure and mechanical properties in order to evaluate their stability conditions.

The present study investigates the landslide dam deposits of a rock avalanche triggered in Yang Jia Gou, in Sichuan Province, using single-station three component recordings of ambient noise, with the aim of obtaining information about thickness and mechanical properties of the deposits from their resonance properties. Three noise measurement campaigns and two ERT surveys were conducted to support data interpretation. The data were analyzed using the traditional Nakamura’s technique, HVNR, and the innovative technique HVIP, both based on the calculation of ratios between horizontal and vertical amplitude of ground motion. Both methods revealed the presence  of resonance peaks, a major one at lower frequency, and a minor one at higher frequencies, representative of the deposit layering. HVNR showed a considerable instability in terms of amplitude of H/V, likely because this technique analyzes the entire noise wave field recorded, so to be subject to a large variability related to a variable composition of the noise field. This problem does not affect the HVIP method, which is based on the analysis of the ellipticity of Rayleigh waves, isolated from the recording.

Rayleigh wave ellipticity curves were used as targets in the inversion phase to obtain the velocity profile of the site. The subsoil model was  constrained by the data derived from the resistivity profiles. The results revealed:  different velocity layers inside the deposit; lateral variations in thickness, in accordance with the higher frequency peak, and in mechanical properties, with an increase of stiffness, probably due to a major portion of rocky blocks; an increase in thickness of the entire deposit, probably because of the irregularities of the substrate.

Further investigations are in progress through other kinds of noise analysis exploiting the synchronization of simultaneous recordings. This can provide additional constraints (to be derived from the dispersion of group velocity of Rayleigh waves) and aid resolving interpretation ambiguities.
Influence on antenna design on range of LoraWAN devices – a practical test
Authors: Roclawski Harald , Krätzig Thomas , Sterle Laura
Published: March 2021

In the research project Iot.H2O, which is funded under the Water JPI Joint Call 2017 IC4WATER, the potential of the Internet of Things concept is investigated for monitoring and controlling water distribution systems. Smart sensors are used which send data among others via LoraWAN to gateways which are connected to the Internet. The aim of the project is to use low-cost sensors and open-source software.

In the presentation, results of a range test with the developed LoraWAN devices are reported. One important factor is the antenna design. Results of tests with 6 different antennas will be presented among them are two antennas which are printed on a PCB and 4 commercially available antennas.

The TTN mapper App is used for recording the signals of the IoT devices in an urban and an rural environment.
Evaluation of seismic sensor orientations in the full moment tensor inversion results
Authors: Jamalreyhani Mohammadreza , Rezapour Mehdi , Büyükakpınar Pınar
Published: March 2021

Three-component seismograms recorded by seismic sensors are momentous data to study the source mechanism of earthquakes. Correct orientation of sensors relative to the true north is important for the waveform inversion techniques. Yet, the non-precise orientation of horizontal components of seismic sensors has been reported in many seismic networks worldwide. In this study, we evaluated the effect of sensor misorientations (deviations from the true north) on time-domain moment tensor inversion, relying on the recent sensor orientation studies on broadband seismic networks in Iran and Turkey. We selected several well-recorded countrywide local and regional moderate magnitude earthquakes, which are associated with the tectonic events, in the time period of 2012-2019. We calculated the moment tensor inversion of those events before and after applying the orientation correction using a Bayesian bootstrap-based probabilistic method. This leads to reaching the uncertainties and trade-offs of parameters and helps to stabilize the inversion. Our analysis shows that in the presence of misoriented sensors, an approximate solution is achievable. However, this includes the remarkable uncertainties in inverted parameters and makes the reliable determination of the moment tensor’s elements challenging. We also found an additional significant non-double couple component while using the misoriented radial and transverse components. Results show that the misfit and uncertainties decrease significantly when sensor orientation correction applied. We suggest that the evaluation of metadata should be part of data processing in seismic networks and data centers, to report more reliable moment tensor solutions.
Constraints on olivine deformation mechanisms from SKS shear-wave splitting beneath the High Lava Plains, Northwestern Basin and Range and Western Yellowstone Snake River Plain
Authors: Löberich Eric , Long Maureen D. , Wagner Lara S. , Qorbani Ehsan , Bokelmann Götz
Published: March 2021

Shear-wave splitting observations of SKS and SKKS phases have been used widely to map azimuthal anisotropy, and to constrain the dominant mechanism of upper mantle deformation. As the interpretation is often ambiguous, it is useful to consider additional information, e.g. based on the non-vertical incidence of core-phases. Depending on the lattice-preferred orientation of anisotropic minerals, this condition leads to a variation of splitting parameters with azimuth and enables a differentiation between various types of olivine deformation. As the fabric of olivine-rich rocks in the upper mantle relates to certain ambient conditions, it is of key importance to further define it. In this study, we predict the azimuthal variation of splitting parameters for A-, C-, and E-type olivine, and match them with observations from the High Lava Plains, Northwestern Basin and Range, and Western Yellowstone Snake River Plain. This can help to constrain the amount of water in the upper mantle beneath an area, known for a consistent, mainly E-W fast orientation, and increased splitting delay in the back-arc of the Cascadia Subduction Zone. Comparing expected and observed variations renders a C-type olivine mechanism unlikely; a differentiation between A- and E-type olivine remains more difficult though. However, the agreement of the amplitude of azimuthal variation of the fast orientation, and the potential to explain larger splitting values, suggest the occurrence of E-type olivine and the presence of a hydrated upper mantle. Along with a discrepancy to predict delay times from azimuthal surface wave anisotropy, deeper sources could further affect shear-wave splitting observations.
Regional Characterisation of soil properties by combining remote sensing, geophysical and pedological methods
Authors: Konen Lars , Mommertz Richard , Rückamp Daniel , Ibs-von Seht Malte , Möller Andreas
Published: March 2021

Knowing our soils well, is the base for a sound land use management, and thus for a worldwide sustainable food production and safe drinking water supply. Especially in countries of the Global South, high quality digital information on soil properties on regional level are rare. While conventional soil inventories are time consuming, digital mapping of soil properties is a promising approach to close the gap more quickly. For this purpose, a reliable method is developed within the BGR project “ReCharBo” (Regional Characterisation of Soil Properties) to minimize field and laboratory work by combining remote sensing techniques like hyperspectral and thermal analyses as well as geophysical methods (e.g. gamma spectrometry) with conventional soil survey from different scales.  At local and field-scale the data acquisition is done by drones, portable equipment and soil sampling, complemented at regional level by helicopter and satellite supported methods. In a corresponding talk in the same session Mommertz et al. (2021) give a detailed technical overview of the selected methods and the research concept of the project. To deploy the method including the concept of ground-truthing on arable land, areas in Germany were selected from Soil Maps of Germany at scale 1:1.000.000 (BÜK1000), 1:200.000 (BÜK200) and 1:50.000 (BK50) depending on representative soil types and region. In a first attempt, the research concept was  carried out with simultaneous field and air borne analyses at two sites  in autumn 2020. The results of this first attempt will be presented at the conference.
Estimating contribution of high-frequency sea-level oscillations to the extreme sea levels in the Adriatic Sea
Authors: Ruić Krešimir , Šepić Jadranka , Karlović Maja , Međugorac Iva
Published: March 2021

Extreme sea levels are known to hit the Adriatic Sea and to occasionally cause floods that produce severe material damage. Whereas the contribution of longer-period (T > 2 h) sea-level oscillations to the phenomena has been well researched, the contribution of the shorter period (T < 2 h) oscillations is yet to be determined. With this aim, data of 1-min sampling resolution were collected for 20 tide gauges, 10 located at the Italian (north and west) and 10 at the Croatian (east) Adriatic coast. Analyses were done on time series of 3 to 15 years length, with the latest data coming from 2020, and with longer data series available for the Croatian coast. Sea level data were thoroughly checked, and spurious data were removed. 

For each station, extreme sea levels were defined as events during which sea level surpasses its 99.9 percentile value. The contribution of short-period oscillations to extremes was then estimated from corresponding high-frequency (T < 2 h) series. Additionally, for four Croatian tide gauge stations (Rovinj, Bakar, Split, and Dubrovnik), for period of 1956-2004, extreme sea levels were also determined from the hourly sea level time series, with the contribution of short-period oscillations visually estimated from the original tide gauge charts.  

Spatial and temporal distribution of contribution of short-period sea-level oscillations to the extreme sea level in the Adriatic were estimated. It was shown that short-period sea-level oscillation can significantly contribute to the overall extremes and should be considered when estimating flooding levels. 
Anomalies in vegetation activity in the early growing season determine the climate-vegetation coupling in Europe
Authors: Wu Minchao , Vico Giulia , Manzoni Stefano , Cai Zhanzhang , Bassiouni Maoya , Tian Feng , Zhang Jie , Ye Kunhui , Messori Gabriele
Published: March 2021

 Recent accelerating global warming with increasing climate variability exerts a strong impact on terrestrial carbon budgets, but the ecosystem response to the changing climate and the overall climate-vegetation coupling remain largely unclear during different stages of the growing season. The timing of growing seasons can be modulated by different environmental conditions (e.g., thermal and hydrological changes) and affect the overall interpretation of regional climate-vegetation coupling. Here, we analyse the climate-vegetation coupling for Europe during 1982–2014 using a grid-wise definition of the growing season period based on remote sensing data. We quantify sub-seasonal anomalies of vegetation greenness from long-term vegetation indices (Normalized Difference Vegetation Index and two-band Enhanced Vegetation Index), and their relationships with corresponding local growing conditions (2m temperature, downwards surface solar radiation and root-zone soil moisture); and with multiple climate variability indices that reflect the large-scale climatic conditions over Europe. We find that early growing season anomalies in vegetation greenness tend to be large during the first two months of the growing season and that the coupling of these anomalies with large-scale climate largely determines the full-year climate-vegetation coupling. The North Atlantic Oscillation (NAO) and Scandinavian Pattern (SCA) phases evaluated one to two months before the start of growing season are the dominant drivers of the early growing season climate-vegetation coupling over large parts of boreal and temperate Europe. However, the sign of the effect of these indices on vegetation greenness is opposite. The East Atlantic Pattern (EA) evaluated several months in advance of the growing season is instead a main controlling factor on the temperate belt and the Mediterranean region. These findings highlight the importance of accounting for the spatial heterogeneity of growing season periods using location-specific definitions when studying large-scale land-atmosphere interactions.
Utilizing galactic cosmic rays as signatures of coronal mass ejections
Authors: Dumbovic Mateja
Published: March 2021

Coronal mass ejections (CMEs) are the most violent eruptions in the solar system. They are one of the main drivers of the heliospheric variability and cause various interplanetary as well as planetary disturbances. One of their very common in-situ signatures are short-term reductions in the galactic cosmic ray (GCR) flux (i.e. Forbush decreases), which are measured by ground-based instruments at Earth and Mars, as well as various spacecraft throughout the heliosphere (most recently by Solar Orbiter). In general, interplanetary magnetic structures interact with GCRs producing depressions in the GCR flux. Therefore, different types of interplanetary magnetic structures cause different types of GCR depressions, allowing us to distinguish between them. In the interplanetary space the CME typically consists of two structures: the presumably closed flux rope and the shock/sheath which is formed ahead of the flux rope as it propagates and expands in the interplanetary space. Interaction of GCRs with these two structures is modelled separately, where the flux-rope related Forbush decrease can be modelled assuming that the GCRs diffuse slowly into the expanding flux rope, which is initially empty at its center (ForbMod model). The resulting Forbush decrease at a given time, i.e. heliospheric distance, reflects the evolutionary properties of CMEs. However, ForbMod is not yet able to take into account complex, non-self-similar evolution of the flux rope. Nevertheless, Forbush decreases can undoubtedly give us information on the CMEs in the heliosphere, especially where other measurements are lacking, and with further development, Forbush decrease reverse modelling could provide insight into the CME evolution.
The Neoproterozoic geomagnetic field: new insights from a high-resolution paleomagnetic study in South China
Authors: Tonti-Filippini Justin , Robert Boris , Muller Élodie , Wack Michael , Zhao Xixi , Gilder Stuart
Published: March 2021

The paleomagnetic record during the middle Neoproterozoic (~825-780 Ma) displays rapid apparent polar wander variations leading to large discrepancies in paleogeographic reconstructions. Some authors propose that these data may represent true polar wander events, which correspond to independent motion of the mantle and lithosphere with respect to Earth’s rotation axis. An alternative explanation might be a perturbation of the geomagnetic field, such as a deviation from a predominantly dipole field or a hyper-reversing field. To test these hypotheses, we sampled 1200 oriented cores over a stratigraphic height of 100 metres in sedimentary rocks of the 820-810 Ma Laoshanya Formation in South China. We will present preliminary paleomagnetic and rock magnetic analyses together with results of petrologic and geochemical experiments to better understand the origin of the paleomagnetic signal.
Modeling of the Russell glacier's basal conditions at seasonal time scale using the satellite observations of surface ice speed
Authors: Derkacheva Anna , Gillet-Chaulet Fabien , Mouginot Jeremie
Published: March 2021

Greenland’s future response to climate change will be determined partly by various phenomena controlling ice flow. For the land-terminating sectors, the water lubricating the glacier's base is considered as a major control on the ice motion. For instance, the seasonal modulations of water input induced by summer melt can cause glacier speed-up up to +200-300% compared to the winter mean. Thus, a comprehensive understanding of variations in the basal conditions, which are at the origin of the glacier flow fluctuations, plays a key role for the climate projections.

While the in-situ measurements stay a local and hard approach to investigate the basal conditions, ice flow modeling offers the possibility to invert for them over the large area based on observations of surface glacier speed and topography. During the last decade, the number of available satellite observations has increased significantly, allowing for far more frequent measurements of the glacier speed and precise reconstruction of the seasonal fluctuations. Here, we investigate the possibility of applying this satellite-derived time-series of surface ice velocity to reconstruct the annual behavior of the basal conditions with 2 weeks temporal resolution using an ice flow model.

The area of this study is Russell glacier located on the southwest coast of Greenland. A time series of surface velocity dataset was created by merging measurements from Sentinel-1&2 and Landsat-8, covering an area up to 100 km inland with 150 m/pix spatial resolution and 2-weeks temporal resolution (Derkacheva et al. 2020). The 3D Full-Stokes ice flow model Elmer/Ice is used to invert for the effective basal friction coefficient for each time step.  Usage of a friction law that has been derived for hard beds (Gagliardini et al., 2007) allows to constrain the variation of the basal effective pressure. Overall, the results from the model inversions give access to the evolution of the basal ice speed, friction, effective and water pressure, floatation fraction throughout a complete year. The results are compared with in-situ measurements in terms of absolute values and show a good agreement. The impact of the flow model setup, regularization, assumptions for the ice rheology, and the impact of noise in the speed data are also examined and compared with in-situ measurements.
Experimental investigation of precession driven flows in a triaxial ellipsoid
Authors: Burmann Fabian , Noir Jerome
Published: March 2021

Precession driven flows are relevant for geo- and astrophysical fluid dynamics as well as industrial applications. In the context of planetary core dynamics, they are attributed to the generation of magnetic fields and/or anomalous dissipation. While precession driven flows have been frequently studied in a cylindrical, spherical or spheroidal container shape, the geometry of a triaxial ellipsoid, representing the geophysical case of core mantle boundary deformation in a tidally locked planet, has received less attention.

Here, we present results from an experimental study in a triaxial ellipsoid. The main focus of our study is on the base flow of uniform vorticity and we report a good agreement between experimental data and existing semi-analytical models. The amplitude of the time averaged uniform vorticity displays a hysteresis loop as a function of the precession forcing and we demonstrate that this observation depends on the ellipticity of the container. Our study also comprises experiments where the boundary layer is expected to be in a turbulent state. Therefore, we discuss the applicability of an effective damping coefficient in the semi-analytical models to account for the dissipation in a turbulent boundary layer. 
On the impact of thunder on droplets
Authors: Kourtidis Konstantinos , Stathopoulos Stavros
Published: March 2021

In the lightning channel pressures can be of the order of 100 atm and hence in the produced thunder, sound pressure levels (SPL) can be very high. Additionally, the thunder frequency spectra have peaks for peal and claps at around 100 Hz and around 50 Hz for rumble sounds, with intracloud lightning having peaks at even fewer Hz. These low frequencies are ideal for acoustically induced orthokinetic agglomeration of droplets. Thunder occurs in cloud environments where not only large numbers of droplets are present, but additionally the shockwave front expands at supersonic velocities in excess of 60 km/s and hence could cause also modulations of droplet size distributions through e.g. vibrational breakup. We present calculations for the two mechanisms above (orthokinetic agglomeration and vibrational breakup) for typical cloud droplet sizes and concentrations. In thunderstorm conditions, it is found that acoustic orthokinetic agglomeration of droplets can be very effective and can produce very rapidly changes in the mean cloud droplet diameter. Also, it is found that the critical Weber number, over which breakup occurs, is easily exceeded in thunderstorm environments and may lead to droplet and ice nuclei breakup. We note that these processes need further study to assess how they could interfere with the lightning generation process itself, through charge redistribution in the modified droplet size distribution spectra. 
Vortices evolution in ideal (M)HD
Authors: Canivete Cuissa José Roberto , Steiner Oskar
Published: March 2021

Vortices and vortex tubes are ubiquitous in the solar atmosphere and space plasma. In order to identify vortices and to study their evolution, we seek a suitable mathematical criterium for which a dynamical equation exists. So far, the only option available is given by the vorticity, which however is not the optimal criterion since it can be biased by shear flows. Therefore, we look at another criterion, the swirling strength, for which we found an evolution equation, which we suggest as a novel tool for the analysis of vortex dynamics in (magneto-)hydrodynamics. We highlight a few results obtained by applying the swirling strength and its dynamical equation to simulations of the solar atmosphere.
 Geo-historical analysis of flood impacts in a large Alpine catchment (Arve River, French Alps, 1850 – 2015).
Authors: Boisson Eva , Wilhelm Bruno , Garnier Emmanuel , Mélo Alain , Anquetin Sandrine , Ruin Isabelle
Published: March 2021

In France, flooding is the most common and damaging natural hazard. Due to global warming, it is expected to globally exacerbate, and it could be even more pronounced in the European Alps that warm at a rate twice as high in the Northern Hemisphere. The Alps are densely populated, increasing exposure and vulnerability to flood hazard. To approach long-term evolutions of past flood occurrence and related socio-economic impacts in relation to changes in the flood risk components (i.e. hazard, exposure and vulnerability), the study of historical records is highly relevant.

To this aim we build and analyze the newly constituted database of Historical Impacts of Floods in the Arve Valley (HIFAVa), located in French Northern Alps and starting in 1850. The database reports flood occurrences and impacts in a well-documented Alpine catchment that encompasses both a hydrological and societal diversity.

We analyze past impacts in regard to their characteristics and evolution in both time and space. Our results show an increasing occurrence of impacts from 1920 onwards, which is more likely related to indirect source effects and/or increasing exposure of goods and people rather than hydrological changes. The analysis reveals that small mountain streams and particularly glacial streams caused more impacts (67%) than the main river. While increase in heavy rainfall and ice melt are expected to enhance flood hazard in small Alpine catchments, this finding calls to pay a particular attention to flood risk assessment and management in small catchments.
Extreme precipitations measured by radar
Authors: Bárdossy András , Pegram Geoff
Published: March 2021

Radar measurements provide information on precipitation in space and time. They do not measure precipitation but reflectivity. The transformation to precipitation is not straightforward.  The result is that different, partly random, partly systematic errors may occur.  Radar precipitation pixels are usually considered to measure the mean over a large area of 500 x 500 m. However the measurement itself is represented in polar coordinates and is subsequently transformed to a Cartesian system. As the measurements in the polar coordinate system deliver areal averages corresponding to different block sizes this is likely to have an effect on the estimates of the true precipitation values. This particularly applies to extremes. In the outer circles of the radar scan the blocks are bigger, and thus the measurements deliver areal extremes where a kind of area reduction factor is the result of the resolution. In order to investigate the influence of this on the extremes two numerical simulation examples were considered. Results from a long high resolution simulation using the String of Beads model applied with data from South Africa, and of a copula based direct simulation, are analysed and presented. The results show that the extremes towards the outer ring of the radar observations may, under stationary conditions, be reduced by up to 20 %.
A low-cost BRIM (Biosphere reserve integrated monitoring)? The example of the Salzburger Lungau & Kärntner Nockberge BR (Austria)
Authors: Jungmeier Michael , Huber Michael
Published: March 2021

UNESCO Biosphere Reserves are model regions for sustainable development per definitionem. Its management is oriented towards meeting the SDGs and to develop practical and innovative solutions on the ground and study interlinkages between global development and local impacts.

Monitoring is thus an essential tool for the effective management of a biosphere reserve. However, resources and capacities at local level are often limited. The authors outline the major conceptual challenges in developing a long-term monitoring system. In the Salzburger Lungau & Carinthian Nockberge UNESCO BR, a BRIM was elaborated between 2011 and 2013 to map the development and performance of the BR based on only 12 indicators. This system allows for collecting data at BR-level to increase the local ability to detect and link long-term social, economic and ecological changes in an easy-to-apply manner. These datasets can provide a valuable contribution to interpret local impacts of global changes and the related impacts of management actions.

The presenters reflect on the practical experiences and outline as well as a way forward towards future options for viable monitoring systems. The presenters assume that the future of biodiversity monitoring will lie in autonomous or semi-autonomous systems. In this context, disruptive technologies (for example, high-resolution remote sensing, bio-acoustics or genetic techniques such as e-DNA , etc.) will play a central role.

Authors:

Michael Jungmeier* und Michael Huber**

* UNESCO Chair for Sustainable Management of Conservation Areas, Carinthia University of Applied Sciences

** E.C.O. Institute of Ecology, Lakeside B07b, 9020 Klagenfurt, Austria
IPCC Data Distribution Centre: FAIR data from Climate Research to Mitigation Policy
Authors: Juckes Martin , Stockhause Martina , Chen Robert S , Xing Xiaoshi
Published: March 2021

The Data Distribution Centre (DDC) of the Intergovernmental Panel on Climate Change provides a range of services to support the IPCC Assessment Process. The role of the DDC has evolved considerably since it was established in 1997, responding to the expanding range and complexity of the data products involved in the IPCC assessment process. The role of the IPCC assessments has also evolved from considering whether anthropomorphic climate change might have unwelcome consequences and how those consequences would vary under different socio-economic scenarios to reporting on the likely outcome of different global policy options.

The DDC works both with datasets which underpin the key conclusions from the assessment and, increasingly, with data products generated by the scientists engaged in the assessment.

Applying FAIR data principles to data products being produced in the highly constrained context of the assessment process brings many challenges. Working with the Technical Support Units of the IPCC Working Groups and the IPCC Task Group, the IPCC DDC has helped to create a process that not only captures information needed to document data products but supports the consistent and clear description of figures and tables within the report.
Climate Zones Classification for Buildings Energy Efficiency Assessment
Authors: Roca Josep , Arellano Blanca , Zheng Qianhui
Published: March 2021

The definition of the building climate zones is the basis for studying the effects of urban climate on building energy consumption and efficiency. In Spain, the transposition of the European Directive on Energy performance of buildings (Directive 2010/31/EU) has been carried out through the Technical Building Code (CTE), which divides the territory into climatic zones through which it evaluates the energy performance of buildings. However, the CTE carries out a climatic division based on administrative criteria ("provinces", NUT3), which leads to oversimplifying the Spanish climatic reality.

In this sense, the paper develops a new methodology for classification maps of climatic zones of buildings in Spain in order to improve the CTE. Therefore, the application in Spain of the CTE, Köppen and ANSI / ASHRAE methodologies are critically studied and compared. A first approach shows inadequacies that could be improve to optimize the energy efficiency of buildings. The climatic data for Spain -provided by the European Climate Assessment & Dataset Project (https://www.ecad.eu/) since 1950 (with a resolution of 1 km2/pixel) are analyzed, and a series of climatic indicators are established (such as the number of summer days, tropical nights, heating degree days, …). Next, OLS and cluster analysis are used as a method to define the Spanish climatic zones. Finally, the research proposes a new climate zones classification for Spain. The new classification provides more detailed climate information for building energy efficiency research and improves the classification defined in the CTE.
Geodynamic Tomography: Constraining Upper-Mantle Deformation Patterns from Bayesian Inversion of Surface Waves
Authors: Magali John Keith , Bodin Thomas , Hedjazian Navid , Samuel Henri , Atkins Suzanne
Published: March 2021

In the Earth’s upper mantle, seismic anisotropy mainly originates from the crystallographic preferred orientation (CPO) of olivine due to mantle deformation. Large-scale observation of anisotropy in surface wave tomography models provides unique constraints on present-day mantle flow. However, surface waves are not sensitive to the 21 coefficients of the elastic tensor, and therefore the complete anisotropic tensor cannot be resolved independently at every location. This large number of parameters may be reduced by imposing spatial smoothness and symmetry constraints to the elastic tensor. In this work, we propose to regularize the tomographic problem by using constraints from geodynamic modeling to reduce the number of model parameters. Instead of inverting for seismic velocities, we parametrize our inverse problem directly in terms of physical quantities governing mantle flow: a temperature field, and a temperature-dependent viscosity. The forward problem consists of three steps: (1) calculation of mantle flow induced by thermal anomalies, (2) calculation of the induced CPO and elastic properties using a micromechanical model, and (3) computation of azimuthally varying surface wave dispersion curves. We demonstrate how a fully nonlinear Bayesian inversion of surface wave dispersion curves can retrieve the temperature and viscosity fields, without having to explicitly parametrize the elastic tensor. Here, we consider simple flow models generated by spherical temperature anomalies. The results show that incorporating geodynamic constraints in surface wave inversion help to retrieve patterns of mantle deformation. The solution to our inversion problem is an ensemble of models (i.e. thermal structures) representing a posterior probability, therefore providing uncertainties for each model parameter.
Observing the disintegration of the Thwaites B30 Iceberg with CryoSat-2 and Satellite Imagery
Authors: Braakmann-Folgmann Anne , Shepherd Andrew , Ridout Andy
Published: March 2021

Icebergs account for half of all ice loss from Antarctica and, once released, present a hazard to maritime operations. Their melting leads to a redistribution of cold fresh water around the Southern Ocean which, in turn, influences water circulation, promotes sea ice formation, and fosters primary production.

To quantify the total volume loss of icebergs both changes in area and in thickness have to be considered. In this study, we combine CryoSat-2 satellite altimetry with MODIS and Sentinel-1 satellite imagery to track changes in the area, freeboard, thickness, and volume of the B30 tabular iceberg between 2012 and 2018. Since it calved the iceberg’s area has decreased from 1500 +/- 60 to 426 +/- 27 km^2 , its mean freeboard has fallen from 49.0 +/- 4.6 to 38.8 +/- 2.2 m, and its mean thickness has reduced from 315 ± 36 to 198 ± 14 m. The combined loss amounts to an 80 +/- 16 % reduction in volume, two thirds (69 ± 14 %) of which is due to fragmentation and the remainder (31 ± 11 %) is due to basal melting.

The quantification of fresh water released from icebergs will help both the risk assessment of maritime operators and the improvement of ocean models by including a realistic – spatially and temporally variable - fresh water flux from iceberg melting in the Southern Ocean. Icebergs can also be used to study the reaction of glacial ice to warming environmental conditions, which they experience when they drift. These conditions might also become present at the ice shelf front in the future and therefore iceberg studies can inform the prediction of ice shelf response to warmer conditions.
Mass flux estimates and their relationship to cloud-base cloudiness during the EUREC4A campaign
Authors: Vogel Raphaela , Bony Sandrine , Albright Anna Lea , Stevens Bjorn , George Geet , Delanoë Julien , Vial Jessica
Published: March 2021

The trade-cumulus cloud feedback in climate models is mostly driven by changes in cloud-base cloudiness, which can largely be attributed to model differences in the strength of lower-tropospheric mixing. Using observations from the recent EUREC4A field campaign, we test the hypothesis that enhanced lower-tropospheric mixing dries the lower cloud layer and reduces near-base cloudiness. The convective mass flux at cloud base is used as a proxy for the strength of convective mixing and is estimated as the residual of the subcloud layer mass budget, which is derived from dropsondes intensively launched along a circle of ~200 km diameter. The cloud-base cloud fraction is measured with horizontally-pointing lidar and radar from an aircraft flying near cloud base within the circle area. Additional airborne, ground- and ship-based radar, lidar and in-situ measurements are used to estimate the total cloud cover, the surface fluxes and to validate the consistency of the approach.

Preliminary mass flux estimates have reasonable mean values of about 15 mm/s. 3- circle (i.e. 3h) averaged estimates range between 0-40 mm/s and reveal substantial day-to-day and daily variability. The day-to-day variability in the mass flux is mostly due to variability in the mesoscale vertical velocity, whereas the entrainment rate mostly explains variability on the daily timescale, consistent with previous large-eddy simulations. We find the mass flux to be positively correlated to both the cloud-base cloud fraction and the total cloud cover (R=0.55 and R~0.4, respectively). Other indicators of lower-tropospheric mixing due to convection and mesoscale circulations also suggest positive relationships between mixing and cloudiness. Implications of these analyses for testing the hypothesized mechanism of positive trade-cumulus cloud feedback will be discussed.
Bringing ESMValTool to the Jupyter Lab
Authors: Kalverla Peter C. , Smeets Stef , Drost Niels , Andela Bouwe , Alidoost Fakhereh , Camphuijsen Jaro
Published: March 2021

Ease of use can easily become a limiting factor to scientific quality and progress. In order to verify and build upon previous results, the ability to effortlessly access and process increasing data volumes is crucial.

To level the playing field for all researchers, a shared infrastructure had to be developed. In Europe, this effort is coordinated mainly through the IS-ENES projects. The current infrastructure provides access to the data as well as compute resources. This leaves the tools to easily work with the data as the main obstacle for a smooth scientific process. Interestingly, not the scarcity of tools, but rather their abundance can lead to diverging workflows that hamper reproducibility.

The Earth System Model eValuation Tool (ESMValTool) was originally developed as a command line tool for routine evaluation of important analytics workflows. This tool encourages some degree of standardization by factoring out common operations, while allowing for custom analytics of the pre-processed data. All scripts are bundled with the tool. Over time this has grown into a library of so-called ‘recipes’.

In the EUCP project, we are now developing a Python API for the ESMValTool. This allows for interactive exploration, modification, and execution of existing recipes, as well as creation of new analytics. Concomitantly, partners in IS-ENES3 are making their infrastructure accessible through JupyterLab. Through the combination of these technologies, researchers can easily access the data and compute, but also the workflows or methods used by their colleagues - all through the web browser. During the vEGU, we will show how this extended infrastructure can be used to easily reproduce, and build upon, previous results.
Lg wave propagation and attenuation characteristics of the NW Himalaya
Authors: Pradhan Kaushik Kumar , Mitra Supriyo
Published: March 2021

Lg waves are formed by the superposition of shear waves trapped within the crustal waveguide and are the most destructive at regional distances. Excitation of Lg waves, its propagation and lateral variability determine the intensity of ground shaking from regional earthquakes. Spatial decay of spectral amplitude of Lg waves have been used to quantify the attenuation characteristics of the crust. In this study we use regional waveform data from the Jammu and Kashmir Seismological NETwork (JAKSNET) to study Lg wave propagation across the Indian Peninsula, Himalaya, Tibetan Plateau and Hindu Kush regions. We compute Lg/Sn wave ratio to distinguish regions with efficient Lg propagation from those with Lg blockage. These results are categorised using earthquake magnitude and depth to study Lg wave excitation and propagation across these varying geological terrains. We further use the two-station method to study Lg wave quality factor and its frequency dependence for the NW Himalaya. Seismograms recorded at two stations of the network, which are aligned within 15 degrees of the event, are used for analysis. The spectral ratio of Lg wave amplitude recorded at the two stations will be used to estimate the Q (quality factor) as a function of frequency. This will provide Q0 along all inter-station paths, which will then be combined to form Q0 tomography maps for the region. Checkerboard tests will be performed to estimate the resolution of the tomographic maps and accordingly the results will be interpreted.
Why is large sample hydrology important in hydrological forecasting? 
Authors: Pechlivanidis Ilias , Crochemore Louise , Girons Lopez Marc
Published: March 2021

The scientific community has made significant progress towards improving the skill of hydrological forecasts; however, most investigations have normally been conducted at single or in a limited number of catchments. Such an approach is indeed valuable for detailed process investigation and therefore to understand the local conditions that affect forecast skill, but it is limited when it comes to scaling up the underlying hydrometeorological hypotheses. To advance knowledge on the drivers that control the quality and skill of hydrological forecasts, much can be gained by comparative analyses and from the availability of statistically significant samples. Large-scale modelling (at national, continental or global scales) can complement the in-depth knowledge from single catchment modelling by encompassing many river systems that represent a breadth of physiographic and climatic conditions. In addition to large sample sizes which cover a gradient in terms of climatology, scale and hydrological regime, the use of machine learning techniques can contribute to the identification of emerging spatiotemporal patterns leading to forecast skill attribution to different regional physiographic characteristics.

Here, we draw on two seasonal hydrological forecast skill investigations that were conducted at the national and continental scales, providing results for more than 36,000 basins in Sweden and Europe. Due to the large generated samples, we are capable of demonstrating that the quality of seasonal streamflow forecasts can be clustered and regionalized, based on a priori knowledge of the local hydroclimatic conditions. We show that the quality of seasonal streamflow forecasts is linked to physiographic and hydroclimatic descriptors, and that the relative importance of these descriptors varies with initialization month and lead time. In our samples, hydrological similarity, temperature, precipitation, evaporative index, and precipitation forecast biases are strongly linked to the quality of streamflow forecasts. This way, while seasonal river flow can generally be well predicted in river systems with slow hydrological responses, predictability tends to be poor in cold and semiarid climates in which river systems respond immediately to precipitation signals.
Afforesting the UK: Potential Hydrological Impacts
Authors: Buechel Marcus , Dadson Simon , Slater Louise
Published: March 2021

Ambitious targets to expand forested land area have increased over the last decade as governments, businesses, and individuals seek to use woodland as carbon sinks. Currently, it is unknown how proposed afforestation rates will influence catchment water resources and hydrological processes. Both the temporal and spatial scale of proposed afforestation are unprecedented on contemporary timescales and we lack the systematic and quantified understanding of its impact on streamflow at catchment scales. Furthermore, the efficacy of afforestation as a form of natural flood management has yet to be tested across multiple catchments (> 30 km2).

 

The UK Government has pledged to use afforestation as a major component of its approach to reach net zero carbon emissions by 2050. In this project, we investigate the influence of afforestation upon streamflow dynamics in twelve catchments across the British Isles. We aim to determine how woodland planting extent and location influences catchment streamflow response and sensitivity, and which catchment attributes account for these changes. To do this, we use physics-based land surface model JULES (Joint UK Land Environment Simulator) at a 1 km resolution to understand the potential hydrological changes to theoretical afforestation scenarios.

 

Land cover afforestation scenarios were created according to proximity to existing land cover, drainage basin structure and afforestation rate (up to 288 potential land cover scenarios per catchment). The period of 2000-2010, a flood-rich period, was used to simulate and compare how each afforestation scenario would influence catchment flow exceedance levels and streamflow regime using the CHESS-met dataset.

 

Results show increasing afforestation has a clear impact upon streamflow dynamics. A strong negative correlation between increasing afforestation and median and low flows exists but is weaker for higher flows. Some afforestation scenarios could increase the highest flows in the period. Quantile regression on the results of our simulations shows a median change of -1.0 ± 0.21 mm yr-1 (-0.26 ± 0.10%) for the median flow exceedance per percentage point of broadleaf woodland planted across all catchments. Planting according to Shreve order, or contributing area, led to statistically significant differences in streamflow dynamics. Climatic catchment attributes correlated strongly with catchment median flow sensitivity to afforestation.

 

These results help us to understand how afforestation may influence catchment response to external climatic forcing.  We hope it provides evidence to policymakers wishing to understand the implications of afforestation on water resources and the foundation to understand its future catchment-scale impacts on streamflow.