bluuebunny/crossref_metadata_2025 huggingface dataset:
The coupling transition depth in subduction zones: rheologically controlled and not constant
Authors: Maunder Ben , Goes Saskia , van Hunen Jeroen
Published: March 2020

The subduction zone coupling transition depth, CTD, marks the transition from frictional/ductile decoupling between the two plates to viscous coupling between the subducting plate and convecting mantle. This depth plays an important role in the state of stress, earthquake potential, and the location of the volcanic arc. Based on previous studies of heat flow and seismic structure of circum-Pacific subduction zones, the CTD has been inferred to at a constant 70-80 km. The mechanism for this constancy remains elusive, although models have reproduced the sharpness of the CTD as a consequence of the evolving strength contrast between a frictional (damage) type rheology along the interface and temperature and stress dependent viscosity in the plates and mantle . Using kinematically driven subduction models with such rheology, we find a relationship between the CTD, slab age and velocity that predicts that 91 % of Pacific subduction zones should have an CTD between 65 and 80 km depth, consistent with observations. However, some other zones are predicted to have significantly deeper or shallower CTD.  For example, a 120 km CTD recently found in the Lesser Antilles can be explained by our models . Sub-arc slab depth is bound by a similar age-velocity relation to that derived for the CTD, but offset to ~50 km larger depths. Hence rheology exerts the primary control on the CTD, and the coupling transition depth is in fact not constant but varies with plate age and convergence.
High impact storms affecting the Iberian Peninsula during 2017-2019 extended winters
Authors: Gonçalves Ana , Liberato Margarida L. R. , Ramos Alexandre M. , Nieto Raquel
Published: March 2020

The occurrence of an increasing number of high impact storms over southwestern Europe (e.g. Klaus, 23-24 January 2009 and Xynthia, 27-28 February 2010; Liberato et al. 2011; 2013) has led to the meteorological services of France (Météo-France), Portugal (IPMA) and Spain (AEMET) to assign names to storms, since 1st December 2017. This new list of named storms has the main objective to better inform the general public and media while contributing to increasing public awareness to high impact storms and associated warnings and timely safety recommendations. The Institute of Meteorology of the Freie Universität Berlin has named all pressure systems in Central Europe since 1954; since 1998, lows are given male names and highs are given female names in odd years, and vice versa in even years. This new list built by the southwestern Europe meteorological services has the main difference of naming only high impact storms.

In this study an analysis of the extreme storms affecting the Iberian Peninsula during the 2017-2019 extended winters is performed. From nine named high impact storms during the 2017-2018 season, seven of them affected the Iberian Peninsula region; and from the thirteen high impact storms during 2018-2019 winter, ten of them affected the region. Firstly an assessment of the strong winds, heavy precipitation and socio-economic impacts is presented. Secondly, a characterization of the synoptic conditions and associated extratropical cyclones is performed. Finally, the events are ranked and classified into the groups previously defined on Karremann et al. (2016) and a variability assessment is made in order to understand how their magnitude and frequency of occurrence fits the identified multi-decadal variability.

Acknowledgements

The authors would like to acknowledge the financial support by Fundação para a Ciência e a Tecnologia, Portugal (FCT), through projects PTDC/CTA-MET/29233/2017 and UIDB/50019/2020 – IDL. A.M. Ramos is supported by Scientific Employment Stimulus 2017 from FCT (CEECIND/00027/2017).

References

Karremann et al. (2016) Atmos. Sci. Let., 17: 354-361 DOI: 10.1002/asl.665

Liberato et al. (2011) Weather, 66: 330-334 DOI: 10.1002/wea.755

Liberato et al. (2013) Nat. Hazards Earth Syst. Sci., 13: 2239-2251 DOI: 10.5194/nhess-13-2239-2013

 
Bayesian Networks for storm surge estimation in Mississippi (US)
Authors: Prida Alvaro , Diaz Loaiza Manuel Andres , Bricker Jeremy , Morales Oswaldo , Meynadier Remy , Duong Trang , Ranasinghe Rosh , Luijendijk Arjen
Published: March 2020

Bayesian Networks for storm surge estimation in Mississippi (US)

A. Prida1, A. Diaz Loaiza1, J. Bricker1, R. Meynadier2, O. Morales-Napoles1, T. Duong3, R. Ranasinghe3, A. Luijendijk1

The unprecedented damage due to flood caused by hurricanes like Katrina (2005) has reinforced the interest of the hydraulic community to improve the storm surge estimation for the North Gulf of Mexico. Very high-resolution hydrodynamic models have been traditionally used for this end. However, these models are computationally very expensive. In this paper, a Bayesian Network (BN) is built to estimate storm surge at the coastal areas of Mississippi. A catalogue of HURDAT2 historical hurricanes is simulated in Delft3D FM to generate a surge data base that is used for the training of the Bayesian Network. The storm surge obtained from Delft3D FM is validated against observations recorded during a past historical event. The landfall location, the maximum wind speed, the forward speed and the forward direction of the hurricane at landfall are the other variables considered in the Bayesian Network. The Bayesian Network is validated by inferring values from past historical events in the model and comparing the modeled surge to observations.
Landslide and Rockfall failures Characterization with Object-Based 3D Analysis
Authors: Karantanellis Efstratios , Marinos Vassilios , Vassilakis Emmanouel
Published: March 2020

Geological failures from massive rockfall failures to small landslides of few cubic meters are a major geological hazard in many parts of the world. Based on the latest developments, close-range photogrammetry and individually UAV photogrammetry and Light Detection and Ranging systems have become indispensable tools for geo-experts in order to provide ultra high-resolution 3D models of the failure site. TLS suffers from the fact that is sometimes tricky to capture the holistic area of interest from the ground, while some areas may often be obscured by vegetation or negative inclinations. The science of photogrammetry has long been used to accurately detect and characterize landslide and rockfall failures. Due to the continuously increasing spatial resolution capability of new generation sensors, traditional pixel-based approaches are not capable to cope with the level of detail resulted from those sensors. Mostly, landslides present complex and dynamic geomorphological features with great heterogeneity in their spatial, spectral and contextual properties dependent on the specific failure mechanism. In the current study, an object-based 3D approach for the automated detection of landslide and rockfall hazard is presented based on detailed topographic photogrammetric point clouds and 3D analysis. Recent trends show that close photogrammetry will play a vital role on the geological and engineering geological assessments concerning geo-failures. The results show that object-based approach is closer to human interception due to integration of contextual and semantic, spectral and spatial information rather than translating pixel’s spectral information solely. The current procedure provides a detailed objective quantification of landslide characteristics and automated semantic landslide modelling of the case site.
Detecting hazardous rivers: the physically-based extreme value distribution (PHEV!)
Authors: Basso Stefano , Domin Andrea , Merz Ralf , Botter Gianluca , Miniussi Arianna
Published: March 2020

Flood frequency curves are the basis to design ordinary engineering structures and devise strategies aimed at mitigating an increasing flood risk. Moreover, they are a crucial tool of risk assessment for insurance and reinsurance purposes. This work is concerned with the presence of abrupt increases of the flood frequency curve (i.e., sudden increments of streamflow magnitudes for a certain return period, named step changes), and investigate their occurrence by means of the physically-based extreme value distribution (PHEV!) of streamflow. This is an analytic probability distribution of extremes, which emerges from a lumped mechanistic-stochastic description of runoff generation and rainfall, soil moisture and discharge dynamics.

In the study, long synthetic time series of streamflow for river catchments exhibiting step changes have been generated and randomly resampled to construct sub-series of decreasing length. These shorter series are then used to test the performance of the PHEV!, of standard purely statistical distributions of the extremes, and of empirical observation-based estimates of the flood frequency curve in detecting the existence of a step change in the long time series from scarce data. Findings show that the PHEV! robustly detects the occurrence of step changes also when only short time series (e.g., 10 years) are used for parameter estimation. Conversely, the alternative methods tested mostly fails in this objective. These results indicate that the PHEV! might be a reliable tool for detecting the propensity of rivers to generate extreme floods in regions lacking long series of discharge observations.
Chronometric measurements in geodesy and geophysics
Authors: Delva Pacôme , Lion Guillaume
Published: March 2020

At the beginning of the 20th century the theories of special and general relativity were developed by Einstein and his contemporaries. These physical theories revolutionize our conceptions of time and of the measurement of time. The atomic clocks, which appeared in the 1950s, are so accurate and stable that it is now essential to take into account many relativistic effects. The development and worldwide comparisons of such atomic clocks allowed for some of the most stringent of fundamental physics, as well as new ideas for the search of dark matter. On a more applied level, when taking general relativity for granted, distant comparisons of atomic clocks can be used for navigation and positioning, as well as the determination of the geopotential. I will show how the chronometric observables can fit and be used within the context of classical geodesy and geophysics, presenting various applications: determination of the geopotential with high spatial resolution, vertical reference system, and discussing the possible applications associated to the geodynamic processes related to mass transfers.
Propagation of a Solar Moving Type IV Radio Burst Using LOFAR
Authors: Liu Hongyu , Zucca Pietro , Magdalenic Jasmina , Zhang Peijin , Cho Kyungsuk
Published: March 2020

Type IV radio burst is the long-lasting broadband continuum emission in metric wave-length. In addition to the continuum emission Type IV radio bursts may show fine structure with high brightness temperature. The physical emission responsible for both continuum and fine structures is still under debate. In this study, we present a moving type IV radio burst observed by LOFAR. We performed a detailed comparison of NRH and LOFAR imaging. Using the full stokes parameterss from the LOFAR dynamic spectra, we have also calculated the degree of circular polarisation during the propagation of the moving type IV. Finally, we combined LOFAR interferometric data with SDO-AIA and LASCO-C2 to track the evolution of this type IV and relate it with the CME.
The Weddell Sea Expedition 2019
Authors: Shears John , Dowdeswell Julian , Ligthelm Freddie , Wachter Paul
Published: March 2020

The Weddell Sea Expedition 2019 (WSE) was conceived with dual aims: (i) to undertake a comprehensive international inter-disciplinary programme of science centred in the waters around Larsen C Ice Shelf, western Weddell Sea; and (ii) to search for, survey and image the wreck of Sir Ernest Shackleton’s Endurance, which sank in the Weddell Sea in 1915. 

The 6-week long expedition, funded by the Flotilla Foundation, required the use of a substantial ice-strengthened vessel given the very difficult sea-ice conditions encountered in the Weddell Sea, and especially in its central and western parts. The South African ship SA Agulhas II was chartered for its Polar Class 5 icebreaking capability and design as a scientific research vessel. The expedition was equipped with state-of-the-art Autonomous Underwater Vehicles (AUVs) and a Remotely Operated Vehicle (ROV) which were capable of deployment to waters more than 3,000 m deep, thus making the Larsen C continental shelf and slope, and the Endurance wreck site, accessible. During the expedition, a suite of passive and active remote-sensing data, including TerraSAR-X radar images delivered in near real-time, was provided to the ice-pilot onboard the SA Agulhas II. These data were instrumental for safe vessel navigation in sea ice and the detection and tracking of icebergs and ice floes of scientific interest.

The scientific programme undertaken by the WSE was very successful and produced many new geological, geophysical, marine biological and oceanographic observations from a part of the Weddell Sea that has been little studied previously, particularly the area east of Larsen C Ice Shelf. The expedition also reached the sinking location of Shackleton’s Endurance, where the presence of open-water sea ice leads allowed the deployment of an AUV to the ocean floor to try and locate and survey the wreck. Unfortunately, SA Agulhas II later lost communication with the AUV, and deteriorating weather and sea ice conditions meant that the search had to be called off.
Mapping strain in the footwall of a thrust: Preliminary results from 3D bulk fabric of illite.
Authors: Aubourg Charles , Francho Gracia-Puzo , Antonio Casas-Sainz , Esther Izquierdo-Llavall , Tiphaine Boiron , Hugo Saur
Published: March 2020

The Sigues fold (Aragon, Spain) presents an exceptional outcrop where 1) the footwall is largely exposed, 2) it is constituted of homogenous shales, 3) the strain varies at distance from the emergent thrust, with all steps of cleavage development. The best model to explain the strain distribution is the trishear propagation of a thrust with a P/S ratio of 1.  However, from East to West, the thrust geometry is changing progressively from blind thrust to flat ramp. The topographic surface as well as the position of the emerging part of the thrust determine the geometry of the structure. This is, therefore, a place with variable geometries, which allow us to describe the different geometric stages of the ramp-and-flat model that we are used to find in major orogenic thrusts.

To map the strain, we measured the magnetic fabric of hundreds of shale fragments (weighting a few grams) in dozens of localities. The magnetic fabric is governed primarily by illite. Hence, the magnetic fabric represents a 3D view of illite organization, i.e. the matrix of those shales (see Gracia-Puzo et al., EGU, EMRP3.8). The measurement of 3D fabric of illite takes about a minute per fragment and is non-destructive.

Magnetic fabric of shale fragments provides three useful parameters, the degree of anisotropy, the shape parameter from oblate to prolate, and the length of the confidence angle of the minimum axis of tensor. We show that all these three parameters are highly sensitive to strain. While each locality provides homogenous results from ~15 fragments (covering few square meters each), it is statistically different from one site to the other, with trends consistent with distance to the main thrust. Assuming rigid rotation of illite particles, we calculate the strain using Eigen values of magnetic fabric tensor.

Our preliminary maps shows: 1) that the strain increases considerably (from units to tens in %) when approaching the main thrust, 2) at a distance of more than 1 km, several strain gradients are detected, suggesting that blind thrusts propagate in the footwall. Serial N-S cross-sections are expected to describe the lateral variability on the structure, the deformation accumulated on the footwall and also establishing the portion of the hanging wall which is being affected and the décollement of the thrust. Our approach is thus promising to map strain in shales from deformed regions, both from natural outcrops, or from boreholes.
Disentangling oxygen depletion in the Benguela Upwelling System: A biophysical approach.
Authors: Herran Natalia , Schmidt Martin
Published: March 2020

Understanding the multilevel complexity of marine ecosystems is one of the greatest challenges on ecosystem modeling so far, due to the dualism of governing hydrodynamical processes acting on a regional scale and complex biogeochemical chain reactions that happen locally on the marine environment. A coupled hydrodynamic-ecological model based on nitrogen stoichiometry has been developed to better understand the short-term nutrient and oxygen coastal dynamics in the Benguela Upwelling System (BUS). The model shows that the effect of internal waves in the Benguela region re-shapes the benthic ecosystem due to the increased of turbulence on the ocean floor with a consequently increase of fine sediment on the water column. We show that an increase on organic-rich sediment resuspension on the water column enhance oxygen consumption and ultimately contribute to the apparent deoxygenation of the Namibian coastal shelf.
Spatialization of meteorological variables over south mediterranean catchments. Case of the Tensift (Morocco).
Authors: Moucha Ahmed , Hanich Lahoucine , Gascoin Simon , Jarlan Lionel
Published: March 2020

The spatialization of meteorological variables when the ground network is scattered and the relief is disturbed is a major issue for watershed hydrology or for the characterization of agricultural water consumption. The aim of this study is to set up the SAFRAN re-analysis system on the Tensift catchment area in Morocco. To this end, all the meteorological measurements acquired on the site between 2004 and 2014 by several organisations were gathered in a single database and quality control was carried out.  SAFRAN was then assessed according to a leave-one-out approach, which consists of removing a station from the database and comparing the re-analysis with the data from this station. It was also compared to another technic for meteorological variables spatialization named MICROMET (Liston et al., 2006). Particular attention was paid on the mountainous areas. In order to reproduce the high climate variability in this area, SAFRAN is also set up with an irregular grid up to 1 km resolution and compared to the regular version (8 km grid point). The results show that the re-analysis on the irregular grid is much better than on the regular grid, especially in the mountains. For example, the validation at the Aremd mountain station (2058 m) shows that the bias and RMSE on the surface temperature decreased from -4.8°C and 6.2°C for the regular grid to 0.6°C and 3.6°C for the irregular grid. Likewise, for precipitation, the correlation coefficient is improved by more than 23% for the regular grid. Concerning the visible radiation, MICROMET is strongly biased compared to the measurements carried out at the Aremd station (86 W/m²) whereas for SAFRAN, the bias is only 48W/m². Our current work concerns the mapping of vertical soil-vegetation-atmosphere exchanges over the catchment area using SAFRAN forcing on the irregular grid. The challenge is notably to represent irrigation, which strongly modifies the surface water states.
Assimilation of Sentinel-2 Leaf Area Index Data into a Physically-Based Crop Growth Model for Yield Estimation
Authors: Novelli Francesco , Spiegel Heide , Sandén Taru , Vuolo Francesco
Published: March 2020

The work is based on a previously published study with the aim to further analyse the results obtained. Remote sensing data, crop growth models, and optimization routines constitute a toolset that can be used together to map crop yield over large areas when access to field data is limited. In this study, Leaf Area Index (LAI) data from the Copernicus Sentinel-2 satellite were combined with the Environmental Policy Integrated Climate (EPIC) model to estimate crop yield. The experiment was implemented for a winter wheat crop during two growing seasons (2016 and 2017) under four different fertilization management strategies. A number of field measurements were conducted spanning from LAI to biomass and crop yields.
LAI showed a good correlation between the Sentinel-2 estimates and the ground measurements using non-destructive method. Better RMSE and RRMSE were obtained in 2017 compared to 2016 (RMSE = 0.44 vs. 0.46) (RRMSE = 17% vs. 19%). In 2016 year, a slightly lower R2 value was found compared to 2017 (R2 = 0.72 vs. 0.89). A correlating fit between satellite LAI curves and EPIC modelled LAI curves was also observed. The work shows that the assimilation of remote sensing data into the crop growth model can help to overtake some structural problems of the model.  The assimilation framework has to be tested under different environmental conditions before being applied on a larger scale with limited field data.
Is bud burst of temperate trees promoted by a critical daylength?
Authors: Pohl Nora , Baumgarten Frederik , Vitasse Yann
Published: March 2020

Is bud burst of temperate trees promoted by a critical daylength?

 

Bud burst of temperate trees is mainly controlled by cool temperatures during winter-dormancy (chilling), warm temperatures in spring (forcing) and daylength (photoperiod). Some tree species may rely more on one of these drivers than others (e.g. temperature driven species) but recent studies emphasize complex interactions among them for most species. As one of these factors, photoperiod can act by preventing trees from flushing too early, minimizing the risk of damaging spring frost. Yet it is unclear whether stimulating and/or inhibiting effects of photoperiod on spring phenology act (i) gradually (i.e. increasing daylength progressively accelerates bud development response to temperature) or (ii) whether photoperiod slows down bud development until reaching a critical threshold.

In this study we tested the second hypothesis by exposing twig cuttings of 5 species (Acer pseudoplatanus, Carpinus betulus, Fagus sylvatica, Quercus petraea, Tilia cordata) to different constant photoperiods that occur before leaf-out in the latitudes of Zurich (10h, 11h, 12h, 13h). Two additional photoperiods of 8h and 16h served as a control to simulate shortest and longest natural occurring daylengths. The experiment was repeated on three occasions (from October 2019 to January 2020) to account for different dormancy depths.  Bud development was monitored twice a week.

The experiment is still running. We expect that temperature-sensitive species would leaf-out regardless of the photoperiod, while photoperiod sensitive species such as beech may wait until a critical threshold has passed. Furthermore, longer photoperiods might substitute for insufficient chilling by decreasing the required amount of forcing to bud burst. The results could serve to better implement photoperiod into phenological models.
North Atlantic SST variability and high impact storms affecting the Iberian Peninsula
Authors: Ferreira Fátima , Liberato Margarida L. R. , Ramos Alexandre M. , Nieto Raquel
Published: March 2020

The Iberian Peninsula has experienced on recent years an increasing number of high impact cyclones (e.g. Klaus, 23-24 January 2009 and Xynthia, 27-28 February 2010; Liberato et al. 2011; 2013) associated with extreme precipitation events, flooding and damage to infrastructure. Recent examples are cyclones Elsa and Fabien, on December 2019, which forced more than 250 people to be evacuated from their homes in Mondego region villages, in central Portugal, due to rising river waters and infrastructure disruption .

However until now not enough evidence has been gathered to confirm a general and significant increase in the frequency and intensity of these events in the north-eastern Atlantic. In fact, according to Karremann et al. (2016) the maximum in recent years is comparable to other stormy periods in the 1960s and 1980s, suggesting that their frequency of occurrence undergoes strong multi-decadal variability.

In this study a high impact extratropical cyclones dataset developed in the framework of project “WEx-Atlantic - Weather Extremes in the Euro Atlantic Region: Assessment and Impacts” is used to assess the variability in frequency and intensity of these events over the last decades in the Iberian Peninsula. A ranking of daily precipitation days for the Iberian Peninsula taking into account not only the area affected but also its average intensity (Ramos et al. 2014) is also used. Additionally, a spatio-temporal variability of sea surface temperature (SST) is performed in the North Atlantic, using ECMWF ERA5 reanalysis data for the period 1979-2019. Finally the relevance of the North Atlantic SST variability on the intensity of these extreme events affecting the Iberian Peninsula on recent winter seasons is discussed.  

Acknowledgements

The authors would like to acknowledge the financial support by Fundação para a Ciência e a Tecnologia, Portugal (FCT), through projects PTDC/CTA-MET/29233/2017 and UIDB/50019/2020 – IDL. A.M. Ramos is supported by Scientific Employment Stimulus 2017 from FCT (CEECIND/00027/2017).

References

Karremann et al. (2016) Atmos. Sci. Let., 17: 354-361 DOI: 10.1002/asl.665

Liberato et al. (2011) Weather, 66: 330-334 DOI: 10.1002/wea.755

Liberato et al. (2013) Nat. Hazards Earth Syst. Sci., 13: 2239-2251 DOI: 10.5194/nhess-13-2239-2013

Ramos et al. (2014) Atmos. Sci. Let., 15: 328–334, DOI: 10.1002/asl2.507
Multi-Sensor Multi-Satellite Remote Sensing of Drought Analysis with Multi-Sectoral Impacts and Multi-Scale Vulnerability in Thailand
Authors: Jirasirirak Sasin , Putthividhya Aksara
Published: March 2020

Drought monitoring and assessment is critical considering the immense costs and impacts Thailand has been experiencing these days.  Deficit in precipitation is typically referred to as meteorological drought.  While deficit in soil moisture (i.e., below average moisture in the soil) is known as agricultural drought.  Hydrological drought corresponds to a deficit in runoff or groundwater resources. Socio-economic drought (also known as anthropogenic drought) refers to water stress intensified by human activities and increase water demands.  Our long-term research in ground observation drought monitoring and assessment has been integrated with remotely sensed precipitation and soil moisture information necessary for the computation of extensively used drought indicators, such as Standardized Precipitation Index (SPI) using widely available satellite-based precipitation products including PERSIANN, TRMM, GSMaP, and IMERG to demonstrate the multidimensional and multi-sectoral impacts of change in rainfall patterns which is directly linked to drought assessment.  Long-term satellite-based soil moisture time series obtained from NASA’s Soil Moisture Active Passive (SMAP) mission have been employed for drought detection from provided near real-time top soil moisture estimates in accordance with The Gravity Recover and Climate Experiment (GRACE) mission.  Preliminary results indicate that multi-sensor multi-satellite remotely sensing data can enhance soil moisture mapping and its long-term spatial and temporal trends match well with change in terrestrial water storage and groundwater storage of the country.   This approach can provide more robust and integrated measure of drought based on wider range of satellite observations such as precipitation, soil moisture, total water storage anomalies, groundwater storage change, offering the opportunities to investigate droughts from different viewpoints. Drought monitoring scheme developed in this work can serve as a supporting tool for water resources and climate change policy making.  It can contribute to improve understanding on potential impacts of climate change, multi-sectoral linkages, multi-scale vulnerability, and adaptation programs.   
Geothermal resources characterization of two areas in southern Tuscany
Authors: Trumpy Eugenio , Gola Gianluca , Santilano Alessandro , Manzella Adele , Brambilla Matteo , Calabrò Roberto , Giussani Marco , Monti Colombani Roberto , Palumbo Salvatore , Savoca Vincenzo , Vajda Emery
Published: March 2020

Based on a joint analysis of geothermal indicators (e.g. temperature map at different depth, surface heat flux) and practical features (e.g. restricted areas, existing research lease), two promising areas in southern Tuscany were identified to perform a more detailed geothermal resource characterization. An area is located on the north-east of the Larderello-Travale geothermal field, and the other one is located on the west of the Mt. Amiata geothermal field.

A quantitative geothermal resources assessment was performed in the aforementioned areas of Tuscany by solving numerical thermo-fluid dynamic models and by computing the geothermal potential using the ‘ThermoGIS’ software, as further developed for the Italian case (Trumpy et al., 2016).

First of all, geological and geophysical data required for geological and thermo-fluid dynamic modelling were collected and organised. The geological data were used to build a 3D geological model of the two areas of interest suitable for numerical simulations. Static temperature data gathered from the Italian National Geothermal Database together with site-specific heat flow measurements were used to calibrate the simulated steady state temperature distribution.

The geothermal potential computed by integrating geological, thermal and petro-physical information implementing the volume method used in ThermoGIS provided estimates of the heat in place and the geothermal technical potential maps. The resulting technical potential in the area close to Larderello –Travale is 330 MWe and in the Mt. Amiata sector is 50MWe.

References

Trumpy E., Botteghi S., Caiozzi F., Donato A., Gola G., Montanari D., Pluymaekers M., Santilano A., Van Wees, J.D., Manzella A. Geothermal potential assessment for a low carbon strategy: a new systematic approach applied in southern Italy. Energy 103, 167-181, 2016.
The effect of geometry on the feed impedance for a PCB-dipole antenna and the time domain radiation emission from the feed point
Authors: Podd Frank , Gao Xianyang , van Verre Wouter , Daniels David , Peyton Anthony
Published: March 2020

The measured reflected radar waveform from an object in free space depends on many factors including the antenna’s geometry, the impedance of the balun and feed-cable, the object position in relation to the antennas, and the object’s angular scattering function. Analytical methods can be simplified when the object is a long way away from the antenna. However, for near-surface GPR applications, such as landmine detection, the objects are generally in the near-field region of the antennas. The ultra-wideband scattering function of objects can be complex even in the far-field.

To optimise GPR antenna design, it is necessary to be able to quickly estimate the Spatio-Temporal Point Spread Function (ST-PSF) for a bi-static antenna pair. Conventionally, the PSF is considered only in the far-field and in the frequencies domain at spot-frequencies. This paper outlines the steps needed to create an analytical approximation of the ST-PSF, and it describes the first step in this process - the parametric modelling of the antenna geometry on feed impedance. The described analysis uses the case of a PCB dipole for both the excitation and the receive antennas as an example of the approach.

The results show the importance of understanding the antenna feed impedance for both the compactness of the radiated pulse and the transfer function of the receive antenna. The paper discusses the optimum cable impedance, assuming a balanced source, and consequentially, the optimum case for matching to heavily damped antenna designs. This paper covers the first step to an analytical approximate of more commonly used (non-damped) dipole antennas.
The Earth Observation Time Series Analysis Toolbox (EOTSA) - An R package with WPS, Web-Client and Spark integration
Authors: Leopold Ulrich , Gräler Benedikt , Bredel Henning , Torres-Matallana J. Arturo , Pinheiro Philippe , Stefas Mickaël , Udelhoven Thomas , Dries Jeroen , Valentin Bernard , Gale Leslie , Mougnaud Philippe , Schlerf Martin
Published: March 2020

We present an implementation of a time series analysis toolbox for remote sensing imagery in R which has been largely funded by the European Space Agency within the PROBA-V MEP Third Party Services project. The toolbox is developed according to the needs of the time series analysis community. The data is provided by the PROBA-V mission exploitation platform (MEP) at VITO. The toolbox largely builds on existing specialized R packages and functions for raster and time series analysis combining these in a common framework.

In order to ease access and usage of the toolbox, it has been deployed in the MEP Spark Cluster to bring the algorithm to the data. All functions are also wrapped in a Web Processing Service (WPS) using 52°North’s WPS4R extension for interoperability across web platforms. The WPS can be orchestrated in the Automatic Service Builder (ASB) developed by Space Applications. Hence, the space-time analytics developed in R can be integrated into a larger workflow potentially integrating external data and services. The WPS provides a Webclient including a preview of the results in a map window for usage within the MEP. Results are offered for download or through Web Mapping and Web Coverage Services (WMS, WCS) provided through a Geoserver instance.

Through its interoperability features the EOTSA toolbox provides a contribution towards collaborative science.
Pollen-based quantitative land-cover reconstruction for northern Asia covering the last 40 ka
Authors: Cao Xianyong , Tian Fang , Li Furong , Gaillard Marie-José , Rudaya Natalia , Xu Qinghai , Herzschuh Ulrike
Published: March 2020

We collected the available relative pollen productivity estimates (PPEs) for 27 major pollen taxa from Eurasia and applied them to estimate plant abundances during the last 40 cal. ka BP (calibrated thousand years before present) using pollen counts from 203 fossil pollen records in northern Asia (north of 40°N). These pollen records were organised into 42 site-groups, and regional mean plant abundances calculated using the REVEALS (Regional Estimates of Vegetation Abundance from Large Sites) model. Time-series clustering, constrained hierarchical clustering, and detrended canonical correspondence analysis were performed to investigate the regional pattern, time, and strength of vegetation changes, respectively. Reconstructed regional plant-functional type (PFT) components for each site-group are generally consistent with modern vegetation, in that vegetation changes within the regions are characterized by minor changes in the abundance of PFTs rather than by increase in new PFTs, particularly during the Holocene. We argue that pollen-based REVEALS estimates of plant abundances should be a more reliable reflection of the vegetation as pollen may overestimate the turnover, particularly when a high pollen producer invades areas dominated by low pollen producers. Comparisons with vegetation-independent climate records show that climate change is the primary factor driving land-cover changes at broad spatial and temporal scales. Vegetation changes in certain regions or periods, however, could not be explained by direct climate change, for example inland Siberia, where a sharp increase in evergreen conifer tree abundance occurred at ca. 7–8 cal. ka BP despite an unchanging climate, potentially reflecting their response to complex climate–permafrost–fire–vegetation interactions and thus a possible long-term-scale lagged climate response.
Stratocumulus Clouds at the West Coast of South America: Observations of Diurnal and Seasonal Cycle
Authors: Schween Jan H. , Westbrook Sarah , Löhnert Ulrich
Published: March 2020

Marine stratocumulus clouds of the eastern Pacific play an essential role in the Earth's energy and radiation budget. Parts of these clouds off the west coast of South America form the major source of water to the hyper-arid area at the northern coast of Chile. Within the DFG collaborative research center 'Earth evolution at the dry limit', for the first time, a long-term study of the vertical structure of clouds and their environment governing the moisture supply to the coastal part of the Atacama is available.

Three state of the art ground based remote sensing instruments were installed for one year at the airport of Iquique/Chile (20.5°S, 70.2°W, 56m a.s.l.) in close cooperation with Centro del Desierto de Atacama (Pontificia Universidad Católica de Chile). The instruments provide vertical profiles of wind, turbulence and temperature, as well as integrated values of water vapor and liquid water. Instrument synergy provides vertical cloud structure information.

We observe a land-sea circulation with a super-imposed southerly wind component. Highest wind speeds can be found during the afternoon. Clouds show a distinct seasonal pattern with a maximum of cloud occurrence during winter (JJA) and a minimum during summer (DJF). Clouds are higher and vertically less extended in winter than in summer. Liquid water path shows a diurnal cycle with highest values during night and morning hours and lowest values during noon. Furthermore, the clouds contain much more liquid water in summer. The turbulent structure of the boundary layer, together with the temperature profile, can be used to characterize the mechanism driving the cloud life cycle.
Boron proxies and biomineralisation: the possible, the impossible and the likely.
Authors: Branson Oscar , Gagnon Alex
Published: March 2020

The abundance and isotopic content of boron in carbonate biominerals provide our best records of ocean carbon chemistry and pH, which have proved instrumental in studying past episodes of CO2-induced climate change. The boron proxies are based on the theory that carbonates solely incorporate B(OH)4- in proportion to seawater B(OH)4-/HCO3- or B(OH)4-/CO32-, capturing both the state of the ocean C system and the pH-dependent isotopic composition of B(OH)4-. However, models of biomineralisation invoke significant modification of internal carbon chemistry to facilitate calcification, and substantial proton export has been observed during carbonate formation. The pH, carbon and boron chemistry at the site of calcification cannot be the same as that of external seawater. How, then, do biominerals appear to record seawater B(OH)4-? While unanswered, this question raises serious problems for our interpretation and use of the B proxies.

We explore this question using a quantitative model of B transport and incorporation in biomineralisation. Three key fluxes dominate biomineral formation: CaCO3 precipitation, the exchange of seawater with the external environment, and ion transport across membranes by diffusion or active pumping. By reducing the problem to the balance between these three key fluxes, it is possible to explore a wide range of biomineralisation scenarios with minimally restrictive assumptions. Within this framework, we consider both the transport of B(OH)4-, and the transport and passive diffusion of membrane-permeable B(OH)3, allowing us to explore a comprehensive range of candidate biomineralisation scenarios and B transport processes.

By explicitly including the independent transport of both B species, our model offers two key insights into the mechanisms behind the boron proxies and biomineralisation:

We identify biomineralisation mechanisms that allow B geochemistry to record external seawater conditions, despite the modified chemistry at the calcification site.

We constrain the dynamics of the calcification environment (e.g. ‘closed’ vs. ‘open’ or Rayleigh- vs. transport-dominated system) by inverting the model to consider paired B/Ca and δ11B data, offering key new constraints on ion transport processes in biomineralisation.
Cosmogenic-nuclide burial ages for Quaternary drilling core sediments in the Yangtze River De, China
Authors: Qi Xiao
Published: March 2020

The establishment of Quaternary drilling core time rulers is an important basis for analyzing the evolution of the Quaternary environment in the plain areas．After analyzing the lithology, color, material composition, sedimentary structure and interface of the Quaternary sediments with a total thickness of 95.5m in YBK1 core in the east side of Yunhe Bridge in Shiqiao Town, Yangzhou City，dividing the stratum in detail，and using dating methods like AMS14C，OSL，cosmogenic nuclide and paleomagnetism. Based on four AMS14C, ten OSL and two 26Al and 10Be burial ages from Quaternary drilling core sediments in the Yangtze River De, the Quaternary stratigraphic-time ruler of YBK1 core was established．The Quaternary sediments is overlying the Pukou group red siltstone，and it is composed of four sets of strata，which from old to new respectively are: the upper part of the early Late-Pleistocene Qidong Group，with age of 0. 1 0. 3Ma，thickness of 30. 20m; the lower part of the early Late-Pleistocene Kunshan Group，with age of 0. 1 0. 045Ma，thickness of 1. 80m; the middle part of the later Late-Pleistocene Gehu Group，with age of 0. 045 ～ 0. 01Ma，thickness of only 3. 40m; the Holocene Rudong Group，with large thickness of 55. 10m. According to the lithological characteristics of YBK1 core，Early-Pleistocene and Early-Middle-Pleistocene sediments are non-existent

Keywords: Quaternary Strata; Burial dating; luminescence dating, the Yangtze River De
Holocene climate in Northern Urals (Komi Republic, Russia): a multi-proxy approach based on pollen and brGDGTs
Authors: Barhoumi Chéïma , Joannin Sébastien , Ali Adam A. , Ménot Guillemette , Golubeva Yulia , Subetto Dmitri , Kryshen Alexander , Drobyshev Igor , Peyron Odile
Published: March 2020

The Holocene climate and its thermal optimum (HTM) are poorly studied in the boreal forests of the northwestern Urals region, particularly in the Republic of Komi. The objective of this study is to provide robust reconstructions of the Holocene climate (temperatures and precipitation) of the Vychegda River basin. The temperature reconstruction is based on pollen assemblages and GDGTs (Glycerol Dialkyl Glycerol Tetraethers). This first study of GDGTs in this area corresponds to a preliminary step for the calibration of this proxy in peats. Higher temperatures and precipitation are recorded between 7000 and 4000 cal. yr BP (mean annual temperatures around 3°C and precipitation between 600 and 700 mm per year. This climatic optimum is in agreement with previous pollen-based climate reconstructions, and climate patterns in the neighboring Russian and Fennoscandia (Komi Republic - previous study-, Arctic Russia, Siberia and Northern Europe, Andreev and Klimanov, 2000; Golubeva, 2008; Seppä et al., 2009a; Novenko et al., 2019). These results, in conjunction with the reconstruction of fire activity and vegetation dynamics in this region, led to a better understanding of the crossed influences of these factors. In particular, vegetation is mainly controlled by climate during the first part of the Holocene, while a threshold is reached on fire frequency after 3500 cal. yr BP and this parameter has a greater impact on vegetation than climate. Over the past 600 years, the intensification of human activities led to overexploitation of the forest and an increase in its fire activity.
Quantitative Detection of Iodine in the Stratosphere
Authors: Volkamer Rainer , Koenig Theodore , Campuzano-Jost Pedro , Saiz-Lopez Alfonso , Jimenez Jose , Fernandez Rafael , Kinnison Doug , Cuevas Carlos
Published: March 2020

Ozone in the extrapolar lower stratosphere is currently declining for reasons that are not well understood. Iodine is emitted mostly from marine sources, and changing iodine emissions provide a possible chemical reason for why ozone in the lower stratosphere continues to decline (Koenig et al., 2020). Previous stratospheric measurements had detected iodine qualitatively in particles. More recently, IO observations in the daytime tropical tropopause layer (TTL) have suggested that between 0.25 to 0.70 pptv Iy are injected into the stratosphere, which is 1.6 to 3.5 times the WMO2014 upper limit. These indirect observations have led to revised estimates of 0 - 0.8 pptv Iy stratospheric injection in the WMO2018 report. This presentation discusses first quantitative measurements of IO radicals and of submicron particulate iodine from aircraft in the stratosphere that support 0.77 pptv Iy stratospheric injection. Our observations support the WMO2018 upper limit estimate, and clearly are incompatible with zero iodine injection. The implications of the obseved iodine concentrations for ozone loss in the lower stratosphere are discussed, also in light of climate records that find increasing iodine in recent decades, observed ozone trends, and ongoing and future research needs to better quantify iodine's contribution to explain these trends. 
Hydro-morphodynamic modelling of floodplains: the role of vegetation in suspended sediment transport
Authors: Conde Daniel A. S. , Boes Robert M. , Vetsch David F.
Published: March 2020

Riverine environments are amongst the most complex ecosystems on the planet. As several anthropogenic factors have increasingly disrupted the natural dynamics of rivers, namely through stream regulation, the need for re-establishing the ecological role of these systems has gained relevance.

Of particular interest are floodplains in compound channels, primarily regarded for safety against floods, but which also comprise an extensive realm for ecological functions and establishment of various species. Floodplain vegetation affects flow resistance and dispersion, playing a fundamental role in erosion and deposition of suspended sediment.

The present work aims at quantifying the interaction between vegetation and suspended sediment transport on floodplains in compound channels by numerical simulations. The employed numerical tool is BASEMENT v3, a GPU-accelerated hydro-morphodynamic 2D model developed at the Laboratory of Hydraulics, Hydrology and Glaciology of ETH Zurich. In the context of the present study, the model is extended with turbulence and suspended sediment transport capabilities. The implemented closure models for turbulence pertain to three major groups, namely (i) mixing-length, (ii) production-dissipation and (iii) algebraic stress models. For suspended sediment transport, the main classical formulations from fluvial hydraulics were implemented in the numerical model.

Laboratory data from flume experiments featuring suspended sediment load and vegetation-like proxies are used for model validation. The numerical results are compared with the observed water depths, velocities and sediment concentrations for different sets of experiments with varying properties, such as density and submergence. The implemented closure models for flow resistance, turbulence and suspended sediment are then combined, calibrated and classified in terms of numerical output quality.

The obtained results from this modelling effort mainly contribute to understanding the applicability of 2D (depth-averaged) models to complex eco-morphodynamics scenarios. The calibration and rating of well-known closure models for turbulence and sediment transport provides relevant guidelines for both future research and practice in fluvial modelling.