bluuebunny/crossref_metadata_2025 huggingface dataset:
AnaEE: a European infrastructure for future-oriented experimental ecosystem research
Authors: De Boeck Hans , Reynaert Simon , Nijs Ivan , Klem Karel , Steenberg Larsen Klaus , Sternberg Marcelo , Boer Michel
Published: March 2020

Human activities are directly and indirectly generating major environmental pressures on ecosystems worldwide through climate change, pollution and other global changes. Altogether, these changes result in a rapid erosion of biodiversity and a perturbation of ecological and agricultural systems and services, prompting urgent societal questions on how to retain or promote sustainable ecosystem services in a global change context. Understanding the responses of ecosystems to such pressures and perturbations, and developing adaptation strategies critically requires state-of-the-art experimental facilities that are able to simulate multiple global change factors. AnaEE (Analysis and Experimentation on Ecosystems) brings together such facilities in a European-wide infrastructure for experimental research on managed and unmanaged terrestrial and aquatic ecosystems. It assists and integrates four types of national platforms (Open-air, Enclosed, Analytical, and Modelling) and provides support to scientists who wish to engage in research projects using these platforms or the data they generate. These services are organised through the Central Hub and three Service Centres (Technology, Data and Modelling, Interface and Synthesis). This integrated approach improves the quality and availability of data and projections on ecosystem responses to global changes, enabling policy makers and stakeholders to make fact-based  decisions on how to sustainably manage ecosystem services. As an example, we shortly discuss the new open air FATI-platform (UAntwerp) in which ecosystems can be exposed to various combinations of precipitation change and warming, and present first results of a study on the impacts of precipitation regime changes on temperate grassland.
Using Machine Learning for processing Big Data of Copernicus Satellite Sensors at the Example of the TROPOMI / Sentinel-5 Precursor and Sentinel-4 Cloud Product
Authors: Romahn Fabian , Argyrouli Athina , Lutz Ronny , Loyola Diego , Molina Garcia Victor
Published: March 2020

The satellites of the Copernicus program show the increasing relevance of properly handling the huge amount of Earth observation data, nowadays common in remote sensing. This is further challenging if the processed data has to be provided in near real time (NRT), like the cloud product from TROPOMI / Sentinel-5 Precursor (S5P) or the upcoming Sentinel-4 (S4) mission.

In order to solve the inverse problems that arise in the retrieval of cloud products, as well as in similar remote sensing problems, usually complex radiative transfer models (RTMs) are used. These are very accurate, however also computationally very expensive and therefore often not feasible in combination with NRT requirements. With the recent significant breakthroughs in machine learning, easier application through better software and more powerful hardware, the methods of this field have become very interesting as a way to improve the classical remote sensing algorithms.

In this presentation we show how artificial neural networks (ANNs) can be used to replace the original RTM in the ROCINN (Retrieval Of Cloud Information using Neural Networks) algorithm with sufficient accuracy while increasing the computational performance at the same time by several orders of magnitude.

We developed a general procedure which consists of smart sampling, generation and scaling of the training data, as well as training, validation and finally deployment of the ANN into the operational processor. In order to minimize manual work, the procedure is highly automated and uses latest technologies such as TensorFlow. It is applicable for any kind of RTMs and thus can be used for many retrieval algorithms like it is already done for ROCINN in S5P and will be soon for ROCINN in the context of S4. Regarding the final performance of the generated ANN, there are several critical parameters which have a high impact (e.g. the structure of the ANN). These will be evaluated in detail. Furthermore, we also show general limitations of ANNs in comparison with RTMs, how this can lead to unexpected side effects and ways to cope with these issues.

With the example of ROCINN, as part of the operational S5P and upcoming S4 cloud product, we show the great potential of machine learning techniques in improving the performance of classical retrieval algorithms and thus increasing their capability to deal with much larger data quantities. However, we also highlight the importance of a proper configuration and possible limitations.
Assessment of droughts and their linkage to environmental flow conditions over a large Indian river basin
Authors: Swain Sabyasachi , Mishra Surendra Kumar , Pandey Ashish
Published: March 2020

A robust characterization and risk assessment of meteorological droughts is the need of the hour considering its pervasiveness and consequences; however, their precise physical quantification is a difficult geophysical endeavor. This becomes a serious issue for India, having 18% of the world’s population and 4% of global freshwater, out of which 83% is used in agriculture. In this study, a detailed spatiotemporal assessment of the meteorological droughts characterized by standardized precipitation index (SPI) at annual scale is carried out over the Narmada Basin, India using the monthly rainfall data from 24 stations for 63 years (1951- 2013). The entire duration was divided into two epochs of 31 years (i.e. 1951-1981 and 1982-2012) for a comparative assessment of drought characteristics. The non- parametric Mann- Kendall (MK) test is applied to investigate the trend of droughts. Further, to predict the environmental Flow (EF) conditions from rainfall data only, the linkage of SPI with the average annual flow (%AAF) is examined over four sub-catchments (Mohegaon, Hridaynagar, Manot, and Sher) of the basin. The results reveal that the Narmada basin is prone to droughts with a frequency of once in 3 to 5 years. The frequency and severity of droughts have significantly increased in 1982-2012 as compared to 1951-1981. The severity of recent droughts shows a more widespread aerial extent in the region. The MK test results indicate an increasing trend in the droughts over most of the stations. An exquisite agreement between SPI and %AAF (used to describe the EF condition) is observed with R2 ranging from 0.757 to 0.988, which shows that coupling SPI with %AAF can be effective for ungauged catchments. This study suggests that appropriate measures must be taken for better management of the water resources in the basin, and also for mitigation droughts, considering the increased risk of the severe drought events in recent decades.
Multiscale observations of NH3 around Toronto, Canada
Authors: Yamanouchi Shoma , Viatte Camille , Strong Kimberly , Jones Dylan B. A. , Clerbaux Cathy , Van Damme Martin , Clarisse Lieven , Coheur Pierre Francois
Published: March 2020

Ammonia (NH3) is a major source of nitrates in the atmosphere, and a major source of fine particulate matter. As such, there have been increasing efforts to monitor NH3. This study examines long-term measurements of NH3 around Toronto, Canada, derived from three multiscale datasets: 16 years of total column measurements using ground-based Fourier transform infrared (FTIR) spectroscopy, three years of surface in-situ measurements, and ten years of total columns from the Infrared Atmospheric Sounding Interferometer (IASI) sensor onboard the Metop satellites. These datasets were used to quantify NH3 temporal variabilities (trends, inter-annual, seasonal) over Toronto to assess the observational footprint of the FTIR measurements, and two case studies of pollution events due to transport of biomass burning plumes.

All three timeseries showed increasing trends in NH3 over Toronto: 3.34 ± 0.44 %/year from 2002 to 2018 in the FTIR columns, 8.88 ± 2.49 %/year from 2013 to 2017 in the surface in-situ data, and 8.78 ± 0.84 %/year from 2008 to 2018 in the IASI columns. To assess the observational footprint of the FTIR NH3 columns, correlations between the datasets were examined. The best correlation between FTIR and IASI was found for coincidence criterion of ≤ 50 km and ≤ 20 minutes, with r = 0.66 and a slope of 0.988 ± 0.058. The FTIR column and in-situ measurements were standardized and correlated, with 24-day averages and monthly averages yielding correlation coefficients of r = 0.72 and r = 0.75, respectively.
FTIR and IASI were also compared against the GEOS-Chem model, run at 2° by 2.5° resolution, to assess model performance and investigate correlation of the model output with local column measurements (FTIR) and measurements on a regional scale (IASI). Comparisons on a regional scale (domain spanning from 35°N to 53°N, and 93.75°W to 63.75°W) resulted in r = 0.62, and thus a coefficient of determination, which is indicative of the predictive capacity of the model, of r2 = 0.38, but comparing a single model grid point against the FTIR resulted in a poorer correlation, with r2 = 0.26, indicating that a finer spatial resolution is needed to adequately model the variability of NH3. This study also examines two case studies of NH3 enhancements due to biomass burning plumes, in August 2014 and May 2016. In these events, enhancements in both the total columns and surface NH3, were observed.
Improving the Co-seismic Slip Distributions of Synthetic Catalogs With Real Observations
Authors: Bayraktar Hafize Başak , Scala Antonio , Festa Gaetano , Lorito Stefano
Published: March 2020

Subduction zones are the most seismically active regions on the globe and about 90% of historical events, including the largest ones with the magnitude M>9, occurred along these regions (Hayes et al., 2018). Most of these events were followed by devastating tsunamis with, in some cases, perhaps unexpected wave height distributions. Observation of events in the megathrust environment reveals that some earthquakes are characterized by slip concentration on the very shallow part of the subduction zone. This shallow slip phenomenon was repeatedly observed in the last two decades for both ordinary megathrust events (e.g. 2010 Maule and 2011 Tohoku) and tsunami earthquakes (2006 Java and 2010 Mentawai). Shallow ruptures feature depleted short–period energy release and very slow rupture velocity possibly due to the presence of (hydrated) sediments (Lay et al., 2011; Lay 2014; Polet and Kanamori, 2000). Associated long rupture durations have been explained with fault mechanics-related rigidity and stress drop variation with depth (Bilek and Lay, 1999) or, more recently, with lower rigidity of surrounding materials (Sallares and Ranero, 2019).

The characteristics of co-seismic slip distribution have an important impact on tsunami hazard. There are numerous methods that have been proposed to generate stochastic slip distributions, also including shallow slip amplification (Le Veque et al., 2016; Sepulveda et al., 2017; Scala et al., 2019). However, these models need to be calibrated against slip models estimated for real events.

Here, we investigate similarities and differences between the synthetic slip distributions provided by Scala et al. (2019) and a suite of 144 slip models of real events that occurred in different subduction zones (Ye et al.,2016). In particular, Scala et al. (2019) model features shallow slip amplification in single events, whose relative probabilities are balanced to restore cumulative slip homogeneity on the fault plane over multiple seismic cycles. This study also aims to improve and/or calibrate this model to account for the behavior observed from real events.
Evaluation of aquifer parameters at regional scale by spectral analysis of discharge time series
Authors: Di Dato Mariaines , Kumar Rohini , Pujades Estanislao , Houben Timo , Attinger Sabine
Published: March 2020

River stream is the result of several complex processes operating at basin scale. Therefore, the river catchment can be conceptualized as a series of interlinked compartments, which are characterized by their own response time to a rainfall event. Each compartment generates a flow component, such as the direct runoff, the interflow and the baseflow. The latter, typically generating from groundwater, is the slower portion of stream flow and plays a key role in studying the hydrological droughts.

In many catchment or large-scale hydrologic models, the groundwater dynamics are typically described by a linear reservoir model, which depends on the state of the reservoir and the parameter, known as recession coefficient or characteristic time. The characteristic time can be considered as the time needed until an aquifer reacts to a certain perturbation. So far, the characteristic time has been estimated by analyzing the slope of the recession (discharge) curve. However, as this method assumes that the recharge is zero within the basin, it may lead to inaccurate estimate when such a hypothesis is not fulfilled in reality.

The present work proposes to infer the characteristic time by using a stochastic approach based on spectral analysis. The catchment aquifer can be viewed as a filter, which modifies an input signal (e.g., rainfall or recharge) into an output signal (e.g., the baseflow or the hydraulic head). Since the transfer function, namely the ratio between the spectrum of baseflow and the spectrum of recharge, is dependent on the aquifer characteristics, it can be used to infer the aquifer parameters. In particular, the characteristic time is evaluated by fitting the spectrum and the variance of the measured baseflow with the analytical stochastic solutions for the linear reservoir. We compare six different methods for hydrograph separation, thereby highlighting a systematic uncertainty in determining the characteristic time due to the choice of filter used. To reduce the uncertainty in fitting, we will use the mesoscale Hydrological Model (mHM) (Samaniego et al., 2010; Kumar et al., 2013) to generate realistic time series for recharge. We apply the spectral analysis method to several river basins in Germany, with the goal to define a regionalization rule for characteristic time.

 

References:

Samaniego L., R. Kumar, S. Attinger (2010): Multiscale parameter regionalization of a grid-based hydrologic model at the mesoscale. Water Resour. Res., 46, W05523, doi:10.1029/2008WR007327.

Kumar, R., L. Samaniego, and S. Attinger (2013): Implications of distributed hydrologic model parameterization on water fluxes at multiple scales and locations, Water Resour. Res., 49, doi:10.1029/2012WR012195
Impact-based early warning for pluvial floods
Authors: Rözer Viktor , Peche Aaron , Berkhahn Simon , Feng Yu , Fuchs Lothar , Graf Thomas , Haberlandt Uwe , Kreibich Heidi , Sämann Robert , Sester Monika , Shehu Bora , Wahl Julian , Neuweiler Insa
Published: March 2020

Pluvial floods in urban areas are caused by local, fast storm events with very high rainfall rates, which lead to inundation of streets and buildings before the storm water reaches a watercourse.  An increase in frequency and intensity of heavy rainfall events and an on-going urbanization may further increase the risk of pluvial flooding in many urban areas.  Current early warning systems for pluvial floods are limited to rainfall predictions with fixed thresholds for rainfall duration and intensity and often do not provide the necessary information to effectively protect people and goods.  We present a proof-of-concept for an impact-based early warning system for pluvial floods. 

Using a model chain consisting of a rainfall forecast, an inundation, a contaminant transport and a damage model, we are able to provide predictions for the expected rainfall, the inundated areas, spreading of potential contamination and the expected damage to residential buildings. We use a neural network-based inundation model, which significantly reduces the computation time of the model chain.  To demonstrate the feasibility, we perform a hindcast of a recent pluvial flood event in an urban area in Germany.  The required spatio-temporal accuracy of rainfall forecasts is still a major challenge, but our results show that reliable impact-based warnings can be issued up to 5 minutes before the peak of an extreme rainfall event.  To effectively disseminate the warnings issued by the model chain we propose a two-way mobile warning application that allows for the collection of real-time validation data.
Transient Tracers and Anthropogenic Carbon in Central Labrador Sea: a Multi-Decadal Study
Authors: Raimondi Lorenza , Azetsu-Scott Kumiko , Tanhua Toste , Yashayaev Igor , Wallace Doug
Published: March 2020

Over the last thirty years the Bedford Institute of Oceanography (BIO) has been maintaining the Atlantic Zone Off-Shore Monitoring Program (AZOMP), which includes annual occupation of several sections and stations in the Northwest Atlantic Ocean. Among these, the AR7W line across the Labrador Sea has one of the longest time-series where both transient tracers and dissolved inorganic carbon (DIC) have been collected since the early 1990s.

Among multiple transient tracers that have been measured along this transect (CFC-11, CFC-113, CCl4 and SF6), only measurement of CFC-12 extends over the full time-series from 1992 to 2018, overlapping with DIC observations. Measurements of CFC-12 were also available for a previous cruise in 1986, extending the time-series to three decades.

In this work we present the temporal variability of CFC-12 (1986-2016) and DIC (1992-2016) concentrations as well as their distribution in the major water masses of the region.

The CFC-12 data are used to reconstruct the time-history of the tracer’s saturation at the time of convection based on multiple regression with the atmospheric input function of CFC-12 and the annual maximum mixed layer depth. The so-modelled time-varying saturation is employed to relax the constant saturation assumption of the Transit Time Distribution (TTD) method, allowing for a better estimate of anthropogenic carbon (Cant) in the region.

We present the column inventories and storage rate of Cant in central Labrador Sea between 1986 and 2016 obtained using the TTD method with time-varying saturation. We compare these estimates with a classical TTD approach that assumes constant saturation, and we highlight the differences in trends and magnitudes obtained with the two approaches.    

Finally, our work shows the multi-decadal dataset of DIC in the Labrador Sea which enables a comparison between the TTD-based Cant estimates and the measured DIC trends, providing insights into temporal variability of natural carbon in the region.
Creep of rock from Barents See, monitored by Acoustic Emissions, Ultrasonic Transmissions and deformation measurements
Authors: Stanchits Sergey , Yarushina Viktoriya , Sabitova Alina , Stukachev Vladimir , Bobrova Maria
Published: March 2020

It is generally known that creep deformation of the rocks, occurring in the Earth under high stress level, influences the fluid flow, as well as other processes related to the strain accumulations. Strain localization across multiple scales is a complex process in any tectonic environment, and is still poorly understood. Because of some technical complications, the majority of laboratory researchers prefer to make a rock testing under deformation control mode, rather than under stress control mode. Three-day multistage loading testing of the mudstone/shale sample collected from the Barents See was conducted in Skoltech in the frame of international project. The loading of the sample was done under 20 MPa confining pressure as a series of consecutive 20 MPa axial stress-steps. After each step, the axial load was kept constant for at least 3 hours’ time interval to study the creeping of the sample, while the monitoring of axial and radial strain allowed to calculate the rock viscosity.
In addition, sixteen Acoustic Emission (AE) sensors were glued to the cylindrical surface of the rock. They were used as well for localization of microcracking within the rock, as for periodical measurement of P-wave velocities along different directions. During the early stage of the rock loading, all velocities demonstrated initial increase related to the compaction of the rock. However, after application of approximately 50% of the maximal axial stress, a strong heterogeneity of P-wave velocity within the rock was recorded, and the decrease of the velocities along some traces indicated occurrence of local dilatancy of the sample. The results of these observations are well correlated with the beginning of AE clustering in the fracture nucleation zone, and both processes were detected during the secondary, steady-state stage of the creep. It was found that the location of AE nucleation zone correlates well with the position of natural crack detected in the sample before the testing by 3D CT X-Ray scanner. 
Macroscopic failure of the sample occurred approximately two minutes after the application of the final stress-step equal to 280 MPa. Analysis of AE signals shows close correlation between the onset of macroscopic fault acceleration, accompanied by significant increase of AE signal amplitudes, and the beginning of tertiary creep stage, detected approximately 25 seconds before the final failure of the sample. Preexisted in the sample natural crack could be considered as healed natural fault, and during our test, we studied activation and creeping of this fault during the stressing of the sample up to the failure, causing observed changes of P-wave velocities, clustering of AE events and variations of rock viscosity.
Analysis of radar and thermal satellite data time-series for understanding the long-term impact of land surface temperature changes on forests
Authors: Prodromou Maria , Yfantidou Anastasia , Theocharidis Christos , Miltiadou Milto , Danezis Chris
Published: March 2020

Forests are globally an important environmental and ecological resource since they retrain water through their routes and therefore limit flooding events and soil erosion from moderate rainfall. They also act as carbon sinks, provide food, clean water and natural habitat for humans and other species, including threatened ones. Recent reports stressed the vulnerability of EU forest ecosystem to climate change impacts (EEA, 2012) (IPPC, et al., 2014). Climate change is a significant factor in the increasing forest fires and tree species being unable to adapt to the severity and frequency of drought during the summer period. Consequently, the possibility of increased insect pests and tree diseases is high as trees have been weakened by the extreme weather conditions. In Cyprus, there are two types of pine trees that exists on Troodos mountains, Pinus Nigra and Pinus Brutia, that may have been influenced by the reduced snowfall and extended summer droughts during the last decades.

 

The overarching aim of this project is to research the impact of Land Surface Temperature on Cypriot forests on Troodos mountains by analysing time-series of radar and thermal satellite data. Impacts may include forest decline that does not relate to fire events, decreased forest density and alternations to timing of forest blooming initiation, duration and termination. Radar systems emitted pulses that can penetrate forest canopy due to the size of its wavelength and, therefore, collect information between tree branches without being affected by clouds. This presentation will focus on radar analysis conducted; testing of various methods, and how the processing pipeline has been automated.

 

The project ‘ASTARTE’ (EXCELLENCE/0918/0341) is co-financed by the European Regional Development Fund and the Republic of Cyprus through the Research Innovation Foundation.
Information Model Governance for Diverse Disciplines
Authors: Hughes John S. , Crichton Daniel J.
Published: March 2020

The PDS4 Information Model (IM) Version 1.13.0.0 was released for use in December 2019. The ontology-based IM remains true to its foundational principles found in the Open Archive Information System (OAIS) Reference Model (ISO 14721) and the Metadata Registry (MDR) standard (ISO/IEC 11179). The standards generated from the IM have become the de-facto data archiving standards for the international planetary science community and have successfully scaled to meet the requirements of the diverse and evolving planetary science disciplines.

A key foundational principle is the use of a multi-level governance scheme that partitions the IM into semi-independent dictionaries. The governance scheme first partitions the IM vertically into three levels, the common, discipline, and project/mission levels. The IM is then partitioned horizontally across both discipline and project/mission levels into individual Local Data Dictionaries (LDDs).

The Common dictionary defines the classes used across the science disciplines such as product, collection, bundle, data formats, data types, and units of measurement. The dictionary resulted from a large collaborative effort involving domain experts across the community. An ontology modeling tool was used to enforce a modeling discipline, for configuration management, to ensure consistency and extensibility, and to enable interoperability. The Common dictionary encompasses the information categories defined in the OAIS RM, specifically data representation, provenance, fixity, identification, reference, and context. Over the last few years, the Common dictionary has remained relatively stable in spite of requirements levied by new missions, instruments, and more complex data types.

Since the release of the Common dictionary, the creation of a significant number of LDDs has proved the effectiveness of multi-level, steward-based governance. This scheme is allowing the IM to scale to meet the archival and interoperability demands of the evolving disciplines. In fact, an LDD development “cottage industry” has emerged that required improvements to the development processes and configuration management.  An LDD development tool now allows dictionary stewards to quickly produce specialized LDDs that are consistent with the Common dictionary.

The PDS4 Information Model is a world-class knowledge-base that governs the Planetary Science community's trusted digital repositories. This presentation will provide an overview of the model and additional information about its multi-level governance scheme including the topics of stewardship, configuration management, processes, and oversight.
Hindcast Simulation of Medicanes with an Atmosphere-Ocean-Wave Coupled Modelling System
Authors: Batıbeniz Fulden , Önol Barış , Turuncoglu Ufuk Utku
Published: March 2020

Tropical-like Mediterranean storms associated with strong winds, low pressure centers and extreme precipitation are called medicanes. These devastating storms threaten the coastal regions and some small islands in the Mediterranean. Recent studies including future climate projections indicate that the intensity of medicanes could increase under the climate change conditions. Therefore it is important to improve a comprehensive understanding of the medicanes and theirs occurrence processes including thermodynamic mechanisms between the atmosphere and the sea. In pursuing these mechanisms, we use reanalysis/observations (ECMWF’s ERA5 and MyOCEAN etc.) and coupled Regional Earth System Model (RegESM). The RegESM model is run in coupled mode (Regional Climate Model-RegCM4-12km coupled with Regional Ocean Modelling System-ROMS-1/12°, and Wave Model-WAM-0.125°) and uncoupled mode (RegCM4 only-12km) for 1979-2012 period over the Med-CORDEX domain prescribed under the CORDEX framework. Additionally, standalone simulation of RegCM4 has been forced by Era-Interim Reanalysis over the Med-CORDEX domain and the standalone simulation of the wave model (WAM) has been forced by the standalone RegCM4 wind field (12 km horizontal resolution) for the Mediterranean Sea.

We analyze the ability of the coupled and uncoupled models to reproduce the characteristics of the observed medicanes and to investigate the role of air-sea interaction in the simulation of key processes that govern medicane occurrences over the study area. In general, the spatial extent and the timing of the observed medicanes better simulated with the coupled model. The reason behind this better replication with the coupled model is the wave model’s interactive contribution with the roughness length to the surface winds, which allows necessary conditions for medicane formation. Our results also reveals that the recently developed modeling system RegESM incorporates atmosphere, ocean and wave components and thereby is better capable to improve the understanding of the mechanisms driving medicanes.

Keywords Regional earth system model, Ocean-atmosphere-wave coupling, Medicanes

Acknowledgements This study has been supported by a research grant 40248 by the Scientific Research Projects Coordination Unit of Istanbul Technical University (ITU) and  a research grant (116Y136) provided by The Scientific and Technological Research Council of Turkey (TUBITAK). The computing resources used in this work were provided by the National Center for High Performance Computing of Turkey (UHEM) under grant number 5004782017.
Measurements of HCl in the volcanic plumes of Calbuco (2015) and Raikoke (2019)
Authors: Clarisse Lieven , Deguine Alexandre , Hultberg Tim , Theys Nicolas , Carn Simon , Fontijn Karen , Decoster Luna , Hadji-Lazaro Juliette , Hurtmans Daniel , Camy-Peyret Claude , Clerbaux Cathy , Coheur Pierre-François
Published: March 2020

Hydrogen Chloride (HCl) is an important but still poorly understood magmatic volatile species. Degassed HCl and ratios with other volatiles can be used to monitor, understand and forecast volcanic activity. As the dominant chlorine reservoir species in the stratosphere, and a source of reactive halogens, HCl also plays an important role in the depletion of ozone. The contribution of volcanic HCl to the stratospheric budget is however somewhat debated, but it is generally accepted that scavenging by hydrometeors is a dominant process. Unlike the less soluble SO2, this prevents the majority of volcanically emitted HCl from reaching the stratosphere. Currently HCl measurements have only been reported from limb sounders (MLS and ACE-FTS in particular), but given their viewing geometry, their vertical sensitivity is limited to the upper troposphere/lower stratosphere. In the past ten years, MLS was able to measure traces of HCl in a number of large volcanic plumes such as those originating from Sarychev Peak, Nabro and Calbuco.

Here, we report the first measurements from IASI of HCl in volcanic plumes. We provide unambiguous spectroscopic identification of HCl in the 2670-2760 cm-1 spectral region in several IASI observed spectra. A survey of 12 years of IASI data was carried out, and revealed several large plumes of volcanic HCl. We show two notably large plumes of HCl identified in the eruptions of Calbuco (2015) and Raikoke (2019). For these two eruptions, we show that HCl is detected in the lower altitude plumes emitted towards the end of the eruptions (and not in the main, higher-altitude and SO2-rich plumes).  This finding could be a result of the greater scavenging of HCl relative to SO2 in rapidly rising plumes, but could also be related to particular degassing mechanics of different volatile components in the erupted melt. First quantitative estimates indicate that for the analysed plumes, the HCl/SO2 molar ratios exceed one, which is much higher than the typical ratios measured by MLS (typically below 0.05) and also higher than reported from petrological data or in situ measurements (typically in the range 0.1-0.3).
Italian travertine in building heritage
Authors: Bellopede Rossana , Marini Paola
Published: March 2020

Travertine is one of the most common stone for building construction used in many countries starting from ancient times. It was one of the favorite stones of the Roman empire: the main example is  the Colosseum in Rome. All over the world travertine is found in important monuments and in various modern structures: for example, the Conservation Center of the J. Paul Getty museum in Los Angeles and Jiangsu Provincial Art Museum in Nanjing, China and it is very appreciated and requested in the construction of recent thermal bath. In addition to Italian travertine, the other famous types of this stone are known throughout Europe (i.e. Germany, Hungary) and Asia (i.e. Turkey, China, Iran).

Travertine is considered a durable stone despite the weathering caused by air pollution. It is observed in urban areas that the facades may be covered with a black crust where gypsum and calcite are the main minerals .

Nine different types of travertine coming from Tuscany and Umbria (Italy) have been investigated. Petrographic analysis, physical mechanical and artificial ageing test have been performed.

Among the different kind of travertine different texture can be identified as: not laminated, laminated: laminated with sub parallel sheets, laminated with concentric sheets. The various travertine depositional structures have been in compared to the different answer to artificial ageing. Finally, it can be asserted that the durability is not connected only with porosity and the analysis of the complex texture of this kind of stone cannot give a simple solution related to its durability.

 
Proterozoic microcontinents in the western Central Asian Orogenic Belt (Kyrgyzstan and Kazakhstan): relationship with Gondwana
Authors: Khudoley Andrey K. , Alexeiev Dmitriy V. , DuFrane S. Andrew
Published: March 2020

Proterozoic microcontinents are widespread in the western part of the Central Asian Orogenic Belt, but their origin remains poorly constrained. The U-Pb dating of detrital zircons in Proterozoic rocks of the southern Kazakhstan and Kyrgyz North Tianshan elucidate depositional ages and evolution of the Precambrian basins and characterize possible links of Precambrian microcontinents in these regions with Gondwana and other cratons.

Distributions of U-Pb detrital zircon ages in 13 samples from ca 5 km thick flysch-like succession of the Talas and Malyi Karatau ranges (Ishim-Middle-Tianshan microcontinent) show significant similarity. They are characterized by a widespread occurrence of Neoproterozoic grains with peaks at ca 820-800 and 910–860 Ma, almost complete absence of Mesoproterozoic grains and distinct peaks at ca 2040–1990 and 2500–2465 Ma for Paleoproterozoic grains. Archean grains occur in small amount. Close similarity is supported by K-S test indicating that samples have the same or similar provenance, also implying rapid accumulation and similar depositional ages. Main peaks resemble those in the Tarim Craton, suggesting Tarim as likely provenance and pointing to the Gondwana affinity of the Ishim-Middle-Tianshan microcontinent.

In contrast, detrital zircon populations in 3 samples from the Neoproterozoic quartzites of the North Tianshan microcontinent are dominated by Mesoproterozoic grains ranging in age from ca 1500 to 1000 Ma and contain few Paleoproterozoic grains ca 1800-1650 Ma. Distributions of U-Pb zircon ages in all 3 samples are very similar and resemble those in the early Neoproterozoic quartzites from the Kokchetav area of northern Kazakhstan, recently reported by Kovach et al. (2017). Age peaks in these samples are very different from the ages of magmatic pulses in Gondwana and point that the North Tianshan microcontinent did not have connection with Gondwana.

The Ishim-Middle-Tianshan microcontinent was rifted out from the Gondwana in late Neoproterozoic and travelled to the north. Origin and travel paths of the North Tianshan microcontinent remain poorly constrained. Widespread occurrence of Mesoproterozoic zircons implies possible links with Baltica, North America or east Siberia, but more detailed study is required to define exact provenance. These two microcontinents welded together in the middle to late Ordovician during amalgamation of the Kazakhstan paleocontinent and were jointly incorporated in Eurasia during the late Paleozoic collisions of the Kazakhstan continent with Siberia, Baltica and Tarim.

The study was supported by RFBR grant 20-05-00252
Exploring Alternative Instrumentation in the Three-Meter Spherical Couette Experiment
Authors: Burnett Sarah , Schaeffer Nathanaël , Ide Kayo , Lathrop Daniel
Published: March 2020

The magnetohydrodynamics of Earth has been explored at the University of Maryland through experiments and numerical models. Experimentally, the interaction between Earth's magnetic fields and its outer core is replicated using a three-meter spherical Couette device filled with liquid sodium that is driven by two independently rotating concentric shells and a dipole magnetic field applied from external electromagnets. Currently, this experiment is being prepared for design modifications that aim to increase the helical flows in the poloidal direction in order to match the turbulence of convection-driven flows of Earth. The experiment currently has 33 hall probes measuring the magnetic field, 4 pressure probes, and torque measurements on each sphere. We supplement the experiment with a numerical model, XSHELLS, that uses pseudospectral and finite difference methods to give a full picture of the velocity and magnetic field in the liquid and stainless steel shells. However, its impracticable to resolve all the turbulence. Our ultimate goal is to implement data assimilation by synchronizing the experimental observations with the numerical model, in order to uncover the unmeasured velocity field in the experiment and the full magnetic field as well as to predict the magnetic fields of the experiment. Through numerical simulations (XSHELLS) and data analysis we probe the behavior of the experiment in order to (i) suggest the best locations for new measurements and (ii) find what parameters are most feasible for data assimilation. These computational studies provide insight on the dynamics of this experiment and the measurements required to predict Earth's magnetic field. We gratefully acknowledge the support of NSF Grant No. EAR1417148 & DGE1322106.
Supraglacial and subglacial meltwater routing in Kongsfjord basin, Svalbard
Authors: Scholzen Chloé , Vikhamar Schuler Thomas , Gilbert Adrien
Published: March 2020

In tidewater glacier fjords, the amount, the spatial distribution, and the timing of meltwater entering the subglacial hydrological system play a key role in modulating ice flow dynamics, as well as in impacting adjacent marine ecosystems. This study aims to describe how meltwater journeys through the polythermal glaciers of Kongsfjord basin in Svalbard, Norway. Our methodology involves the use of a surface runoff timeseries (2003-2017) from a coupled surface-energy-balance-snow model forced by a regional climate model (HIRLAM). Using a program for flow pathways analysis in DEMs (TopoToolbox), we generate a map of surface meltwater streams and drainage catchment areas. Other supraglacial features such as melt lakes, moulins and crevasses are manually detected from satellite imagery. These serve as basis to create four different setups of water input to a subglacial drainage model (GlaDS): (1) a spatially continuous input that equals the surface runoff, (2) a discrete input where the total surface runoff over the whole Kongsfjord basin is equally distributed between moulins, (3) a discrete input where upstream catchment areas are taken into account to weight the runoff drained into each moulin, and (4) a hybrid configuration of (1) and (3) where in crevassed areas the input equals the surface runoff, while in non-crevasses areas moulins are fed by upstream catchment runoff. The subglacial drainage model, which allows for meltwater to flow through both an inefficient distributed network of linked cavities, and a more efficient channelized system, yields spatiotemporal information on basal water pressure, sheet discharge and channel discharge, as well as on channel location. Results for the four water input setups are compared, and we discuss the relevance of using a more realistic configuration of meltwater recharge when modeling hydrological systems underneath glaciers. Finally, based on our model outputs, we provide seasonal maps of Kongsfjord basin’s subglacial hydrology that show the preferential flow path of basal water and through which glacier outlet meltwater is released into the fjord.  
Methodological analysis for decision-making regarding solid waste management in megacities
Authors: Solano Johanna , Orjuela Yepes David , Rodrigo-Ilarri Javier
Published: March 2020

Pronosticar la generación de residuos sólidos se ha convertido en un tema fundamental para dimensionar los elementos técnicos (generación, recolección, transporte, transferencia, uso y disposición final) y políticos (legislación, grupos de interés, sostenibilidad financiera) con respecto a la gestión integral de residuos sólidos en megaciudades. Para poder hacer este tipo de predicciones, es necesario diseñar modelos matemáticos que permitan el análisis de cada variable asociada con esta gestión, teniendo en cuenta las particularidades y necesidades locales de gestión de residuos.

Se pueden incluir varios modelos en cada etapa de la gestión integral de residuos sólidos urbanos. Actualmente, existen modelos que utilizan inteligencia artificial para pronosticar la generación de residuos sólidos urbanos, diseñar rutas de recolección y seleccionar el tipo de disposición final. Sin embargo, es necesario integrar estos modelos que respondan al contexto de cada población. Para lograr esto, es necesario conocer las características de cada ciudad, así como las diferentes variables implícitas dentro del proceso para desarrollar metodologías concretas, que se convierten en herramientas útiles para las administraciones municipales. Sin embargo, las metodologías existentes no incluyen un análisis de los impactos asociados con cada etapa del proceso de gestión de residuos, como criterio para seleccionar las mejores estrategias de gestión. 

Therefore, this methodological proposal includes a stage to evaluate the possible impacts caused by the selected alternative, for which a life cycle analysis is proposed as a tool to determine possible environmental, economic and social impacts. This analysis will be carried out by gathering the corresponding information, as well as using specific software to obtain the data that feeds the model for subsequent decision-making.

Esta propuesta introduce diferentes tipos de modelos en cada etapa del proceso para obtener resultados integrales y más precisos con respecto a las necesidades de una megaciudad. La propuesta se basa en variables y datos reales de acuerdo con las particularidades de las ciudades, para minimizar los posibles errores en la toma de decisiones. Al introducir herramientas cuantitativas para analizar la gestión de residuos sólidos urbanos, la metodología propuesta omite posibles evaluaciones cualitativas o basadas en la percepción, lo que lleva a que los resultados obtenidos sean cada vez más realistas, ya que tienen en cuenta las necesidades reales de cada población.
Revisiting Toba Caldera: an insight from regional magnetotelluric data
Authors: Sutrisno Lukman , Beekman Fred , Daud Yunus , Van Wees Jan Diederik
Published: March 2020

Regional magnetotelluric (MT) survey had been conducted to image resistivity structures beneath Toba Caldera, Indonesia. A crustal-scale 2D inversion model is generated from ten MT stations with extended recording time, deployed along NE-SW regional line to cross perpendicularly both the Caldera and the nearby regional strike-slip fault system, the Sumatran Fault. High resistivity background is likely related to Palaeozoic rocks which is basement of the Tertiary sediments and the Quaternary volcanics. The most noticeable conductive anomaly is located between 10-20 km deep, interpreted as the main magma reservoir beneath the region. An intermediate, less than 10 km-deep, less conductive anomaly beneath the Caldera is interpreted as shallow magma chamber affected by the last major eruption. Shallow, less than 2 km-deep conductive layers are associated either with hydrothermal clay cap beneath the Caldera, or sedimentary formations of the nearby basins. Other conductive anomaly is spatially associated with the Sumatran Fault which located 15 km away from the Caldera. Parameter plots of some stations are consistent with the orientation of basement structures, while the others may be affected by more complex caldera structures. A conceptual model of magma plumbing system beneath the Caldera is then interpreted from the combination of regional resistivity structures, surface geology, and available seismic tomography.
Exhumation of HP/UHP rocks by normal ductile shearing on top of the Eocene extruding wedge
Authors: Ballèvre Michel , Manzotti Paola
Published: March 2020

A popular model for the exhumation of HP-UHP rocks is the ‘extruding wedge’ model, where a crustal slice is bounded at its base by a ‘thrust shear-sense’ fault and to the top by a ‘normal shear-sense’ fault. In the Western Alps, the late Eocene Combin Shear Zone (CSZ) allowed extrusion of a wedge made by the Briançonnais-Piemonte-Liguria (‘Penninic’) stack.

Geological mapping has established the geometry and continuity of the CSZ from the frontal part of the Dent Blanche Tectonic System to the western boundary of the Sesia Zone. The CSZ has been cut during the Miocene by the brittle Aosta-Ranzola Fault, with an estimated downthrow of the northern block of c. 2.5 km with respect to the southern block. Consequently, the sections observed north (Monte Rosa) and South (Gran Paradiso) of the Aosta Fault display different structural levels in the Alpine nappe stack. The CSZ has been folded (Vanzone phase) during the final part of its history (i.e. when displacement along the CSZ was no more taking place), due to the indentation of the Adriatic mantle. This offers us the unique opportunity to study the change in deformation mechanisms along the shear zone (for a distance parallel to its displacement of about 50 km).

Salient characteristics of the CSZ are the following. (i) The thickness of the ductile shear zone increases from NW (frontal part of the Dent Blanche) to SE (frontal part of the Sesia Zone), from a few hundred metres to several kilometres. The type of lithologies pervasively reworked by the ductile shear changes along strike (dominantly calcschists from the topmost oceanic units in the Combin Zone, possibly up to the whole of the ‘Gneiss Minuti’ in the frontal Sesia Zone). (ii) The main ductile deformation along the CSZ was taking place at greenschist-facies conditions, overprinting eclogite-facies to greenschist-facies deformations of Cretaceous to Middle Eocene age. The CSZ is cutting and reworking eclogite-facies structures developed in its hangingwall (Sesia) as well as in its footwall (Zermatt). (iii) Ductile displacement along the CSZ is associated with the development in its footwall of south-east-verging, kilometre-scale, folds (Mischabel phase). The sedimentary sequences of the Pancherot-Cime Bianche-Bettaforca Unit may be used to estimate the minimum amount of ‘normal shear sense’ displacement of the order of 15-20 km.

A kinematic model integrating slab roll-back, ‘thrust shear-sense’ at the base and ‘normal shear-sense’ displacement on top of the Eocene eclogite-facies stack will be presented.