bluuebunny/crossref_metadata_2025 huggingface dataset:
Active tectonics and seismicity in the Calabrian Arc subduction complex (Ionian Sea)
Authors: Polonia Alina , Tiziana Sgroi , Andrea Artoni , Graziella Barberi , Andrea Billi , Luca Gasperini , Luigi Torelli
Published: March 2020

The Calabria Arc (CA) is the narrowest subduction-rollback system on Earth, and it has been struck repeatedly by destructive historical earthquakes often associated with tsunamis. In spite of the detailed earthquake catalogue, the source parameters of most historic earthquakes are still debated, especially for earthquakes that may have been generated offshore.

The subduction system is characterized by an irregular plate boundary reflecting the presence of continental blocks, indenters, and different rates of continental collision. Convergence between Eurasia and Africa produces both compressive and transtensional deformation in the offshore accretionary complex. Shortening occurs along the outer deformation front and along splay faults accommodating differences in rheology and basal detachment depth. Two oppositely dipping strike-slip/transtensional fault systems, i.e., the Ionian (IF) and Alfeo-Etna (AEF) faults produce deep fragmentation of the subduction system and the collapse of the accretionary wedge, in agreement with geodetic models suggesting plate divergence in this region. Transtensional lithospheric faults segmenting the subduction system are punctuated by mantle-rooted diapirism driven by arc orthogonal rifting, collapse of the accretionary wedge, and deep fragmentation of the subduction system along pre-existing Mesozoic transform faults.

Seismological observations in the Western Ionian Sea highlight the presence of earthquake clusters along wide and deep-seated active tectonic structures, which were proposed as likely seismogenic sources for large magnitude historic earthquakes/tsunamis in the region. Low to moderate magnitude earthquakes occurring offshore were relocated using a new 1D velocity model for the Ionian Sea, constrained by geological and geophysical observations, which included data collected by NEMO-SN1 seafloor observatory. Seismological data from NEMO-SN1 were integrated with observations carried out by over 100 land stations of the INGV network, and led us to compile a map of 3D distribution for over 2600 events. 3D locations and focal mechanism analyses allowed us to highlight local lithospheric structure. Although seismicity appears scattered in a wide corridor of deformation within the subduction system, we observe alignments of events along main fault systems with strike-slip and extensional mechanisms. Moreover, results from seismological data analysis, i.e., misfits in the 3D distribution of hypocenters and tomographic maps, could be explained by the presence of an anomalous area between the two structures, characterized by thinned lithosphere probably caused by incipient rifting, as suggested by seismic reflection images and geodynamic interpretations.  
Reflection Seismic Interpretation of Topography and Acoustic Impedance beneath Thwaites Glacier, West Antarctica
Authors: Clyne Elisabeth , Anandakrishnan Sridhar , Muto Atsuhiro , Alley Richard , Voight Donald , Riverman Kiya
Published: March 2020

Thwaites Glacier (TG), West Antarctica, is losing mass in response to oceanic forcing. Future evolution could lead to deglaciation of the marine basins of the West Antarctic ice sheet, depending on ongoing and future climate forcings, but also on basal topography/bathymetry, basal properties, and physical processes operating within the grounding zone. Hence, it is important to know the actual distribution of bed types of TG’s interior and grounding zone, and to incorporate them accurately in models to improve estimates of retreat rates and stability. Here we determine bed reflectivity and acoustic impedance via amplitude analysis of reflection seismic data. We report on the results from two lines – a longitudinal (L-Line) and a transverse (N-Line) – on a central flowline of TG 100 km inland from the grounding zone. There is considerable variability in bed forms and properties, both within this dataset and in-comparison with nearby work. Notably, we find the same hard (bedrock) stoss and soft (till) lee pattern observed elsewhere on TG in prior work. Physical understanding indicates the basal flow law describing motion over different regions of TG’s bed likely varies from nearly viscous over the hard bedrock regions to nearly plastic over soft till regions, providing a template for modeling.
Dynamic Stress Concentration Around Shallow-Buried Circle Cavity Under Transient P Wave Loads in Different Conditions
Authors: Tao Ming , Huang Linqi , Li Xibing , Wang Shaofeng
Published: March 2020

Based on the large-arc assumption, an analytical model is established and solved by using the complex variable function method to illustrate the dynamic stress concentration around a shallow-buried cavity under transient loads. The jump points in the dynamic stress concentration factor (DSCF) curve that do not in line with the overall trend is filtered out to obtain more reasonable results. The convergence speed of the Graf addition formula is examined, as well as the effects of the incidence angle, frequency, and burial depth on the DSCF around the cavity. Examples show that a larger arc radius and a higher incident frequency correspond to slower convergence of the Graf addition formula. There are differences between the DSCF distributions of high-frequency incidents (such as blasting waves) and low-frequency incidents (such as seismic waves). There are three tensile-stress zones and three compressive-stress zones approximately equally spaced around the cavity in the low-frequency case, and there are two tensile-stress zones and two compressive-stress zones in the high-frequency case. Regarding the variation of the DSCFs with respect to the cavity depth, incidence angle and position of wave peak there are significant differences between the high- and low-frequency cases.
Radiative Properties of Aerosols and Clouds from Observations and Models over the Southeast Atlantic
Authors: Chang Ian ,   NASA ORACLES Team
Published: March 2020

The southeast Atlantic serves as a natural laboratory for studying aerosol-cloud-radiation interactions due to the abundant presence of quasi-permanent stratocumulus and overlying biomass burning smoke aerosols during austral winters. Aerosol and cloud properties from the Spectrometers for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) and Solar Spectral Flux Radiometer (SSFR) on board NASA P-3 and High Spectral Resolution Lidar (HSRL) on board NASA ER-2 during the NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) field campaign are used to compare with satellite retrievals. Aerosol and cloud properties from regional climate models such as WRF-Chem, WRF-Chem (with CAM5), ALADIN, GEOS-CHEM, EAM-E3SM, MERRA-2, and GEOS-5 with aerosol schemes are also compared against airborne measurements and satellite retrievals to evaluate and address the current model deficiencies in the southeast Atlantic. A preliminary estimate of the direct aerosol radiative effects over the southeast Atlantic will be presented.
Nitrogen isotope evidence for the stepwise oxygenation of the mid-deep ocean across the Yangtze Block during the Ediacaran-Cambrian transition in South China
Authors: Tian Hui , Gai Haifeng , Wu Yaowen
Published: March 2020

The Ediacaran–Cambrian (E–C) transition witnessed profound biological and oceanic changes, among which the appearance of explosive radiation of skeletonized animals is considered as the most remarkable one. Although the prominent rise of oxygen concentration in atmosphere and ocean is believed to be the major trigger of the “Cambrian Explosion”, it is still an open question about the persistence of anoxic/ferruginous deep waters. In this study, the δ15Nbulk, δ13Corg values, TOC and TN contents, as well as trace elements concentrations of Well ZK4411 fresh core samples are analyzed to explore redox conditions of deep ocean, the nitrogen cycle and their relationships with biological evolution. The Mo concentrations, Mo–U covariations and Th/U ratios of studied samples indicate the oxic water condition of the mid-depth ocean during the late Ediacaran and Cambrian Fortunian stage, widespread anoxic/euxinic water conditions with temporarily sulfidic water condition during Cambrian Stage 2 and early Stage 3, and oxic water condition during the middle and late Stage 3. Based on a combination of δ15Nbulk values from this study and other published data, the low δ15Nbulk values (4+ assimilation in the photic zone, and the extinction of Ediacaran-type and small shelly-type animals during widespread anoxic event of Cambrian Stage 2 and early Stage 3. However, the high δ15Nbulk values, close to those of modern ocean sediments, imply that an established large NO3− reservoir and the existence of the well-oxygenated mid-depth ocean during the middle to late Stage 3, which is coincident with the appearance of larger, diversified skeletonized animals as exemplified by the Chengjiang Biota. All these results indicate a stepwise oxygenation of the early Cambrian deep ocean and an increasing supply of nitrogen nutrient, which leads to the Cambrian diversification and ecological radiation.

 
High-field slope correction of hysteresis loops: are we doing it correctly?
Authors: Zhao Xiang , Roberts Andrew , Heslop David
Published: March 2020

Presentation of magnetic hysteresis data has long been a standard component of paleomagnetic, rock magnetic, and environmental magnetic publications. It has become standard practice to correct the high-field slope of hysteresis loops using a line fit through data points between 70 and 100% of the maximum applied field. Implicit to this approach is that the magnetization is considered saturated if the loop is closed at the point at which 70% of the maximum applied field is reached. This approach treats hysteresis overly simplistically because it assumes that the irreversible magnetization, which is what gives rise to hysteresis, is the only relevant part of the magnetization. The reversible component of magnetization is also important; this component approaches saturation non-linearly following the so-called law of approach to saturation, where the magnetization continues to increase due to rotation of magnetic moments parallel to the applied field, which is resisted by the anisotropy of the material. Various mathematical formulations exist for the law of approach to saturation. Use of this law is not straightforward for geological materials because terms in the respective equations depend on the material analysed and must be approximated, which becomes problematical for samples with mixed magnetic components. Alternatively, hysteresis loops can be fitted and extrapolated to high fields to estimate the approach to saturation using hyperbolic functions. We illustrate issues associated with linear slope correction at 70–100% of the maximum applied field by comparing hysteresis parameters estimated using approach to saturation fitting with various maximum applied fields. In all cases, for maximum fields used typically in mineral magnetic studies (e.g., 1 T), conventional slope correction underestimates the saturation magnetization Ms and overestimates the ratio of the saturation remanent magnetization Mrs to Ms. Hysteresis loop undersaturation is likely to be widespread in mineral magnetic studies with inadequate slope correction probably causing a large uncertainty in published hysteresis parameters. We recommend routine application of approach to saturation fitting of hysteresis loops, which can help to better estimate Ms and Mrs/Ms, as well as help to indicate whether a maximum applied field is sufficient to achieve magnetic saturation.
Rifting, magma, and break-up in Central Afar
Authors: Bellahsen Nicolas , Pik Raphael , Leroy Sylvie , Ayalew Dereje , Doubre Cécile
Published: March 2020

In Afar, an active mature rift, close to break-up have been described for many decades. However, no data were provided so far to precisely constrain the long-term structure of the rift, its evolution, and the rift maturity, i.e. the documentation of ongoing break-up processes. Here, we synthetize structural, geophysical, and geochemical data that show that break-up is indeed ongoing in Central Afar.

Geological mapping and dating of volcanic units provided data to build a detailed surface cross-section, showing a dense network of continentward dipping normal faults and two main unconformities. The field cross-section allows to estimate the amount of crustal thinning and stretching (beta factor > 2.5 in the rift center). The crust first stretched quite uniformly during late Oligocene-early Miocene times and then thinned is a more localized manner during late Miocene times. Subsequently, during Plio-Quaternary times the volcanic Stratoïd series emplaced in the thinned area. Eventually, the present-day magmatic axes have been active for about 500 kyr in the thinned continental crust.

The crust decreases in thickness from 40 km beneath the Ethiopian plateau to about 20-25 km in Central Afar, from receiver functions (RF). New RF data and tomographic models confirm that thickness and show that a necking zone formed at depth most likely during late Miocene times (thinning phase).

The combination of geological and geophysical data allows to attempt for balancing the cross-section. This balancing suggests that, beneath Central Afar, the crust is much thicker than it should be. This crust in excess is interpreted as representing magma intrusions and/or underplating that occurred in the course of the Cenozoic rifting.

Trace element analyses suggest that the depth of melting has strongly decreased just after the plume impingement, suggesting an early thermal erosion of the lithosphere base. Geochemical (isotopic) data show that in Central Afar most of the magma sources were in the plume head/tail since its impingement. These data also show that the recent lavas (< 500 kyr) were almost not contaminated by continental crustal rocks, attesting for a transitional crust beneath Afar and suggesting a recent switch from crustal thinning to dyke-related divergence.

To sum up, we propose that (1) the Afar plume was channelized in the lithosphere, probably since late Oligocene times, (2) a late Miocene thinning event (necking) predated a Quaternary SDR-like volcanic wedge emplacement, and (3) divergence is now accommodated by magmatic accretion.
In situ ground based measurements of low level clouds during 10 years of Pallas cloud experiments.
Authors: Doulgeris Konstantinos , Brus David
Published: March 2020

Clouds and their interaction with aerosols are considered one of the major factors that are connected with uncertainties in predictions of climate change and are highly associated with earth radiative balance. Semi long term in-situ measurements of Arctic low-level clouds have been conducted during last 10 year (2009 - 2019) autumns at Sammaltunturi station (67◦58´N, 24◦07´E, and 560 m a.s.l.), the part of Pallas Atmosphere - Ecosystem Supersite and Global Atmosphere Watch (GAW) programme. During these years a unique data set of continuous and detailed ground-based cloud observations over the sub-Arctic area was obtained. The in-situ cloud measurements were made using two cloud probes that were installed on the roof of the station: the Cloud, Aerosol and Precipitation Spectrometer probe (CAPS) and the Forward Scattering Spectrometer Probe (FSSP), both made by droplet measurement technologies (DMT, Longmont, CO, USA). CAPS in­cludes three instruments: the Cloud Imaging Probe (CIP, 12.5 μm-1.55 mm), the Cloud and Aerosol Spectrometer (CAS-DPOL, 0.51-50 μm) with depolarization feature and the Hotwire Liquid Water Content Sensor (Hotwire LWC, 0 - 3 g/m3). Vaisala FD12P weather sensor was used to measure all the meteorological data. The essential cloud microphysical parameters we investigated during this work were the size distributions, the total number concentrations, the effective radius of cloud droplets and the cloud liquid water content. The year to year comparison and correlations among semi long term in situ cloud measurements and meteorology are presented.
Statistical analysis of Swarm satellite data for assessing the effectiveness of ionospheric precursors of earthquakes
Authors: De Santis Angelo ,   SAFE Team
Published: March 2020

Analysing ionospheric electron density and magnetic field data from several years of the Swarm three-satellite mission we define a dataset of anomalies statistically.  We then use a superposed epoch approach to study the possible relation with a corresponding dataset of earthquakes occurred in the same space-time domain. Two statistical quantities d and n are then established comparing the statistics of the real analyses with simulations to assess the effectiveness of the largest concentrations of anomalies as ionospheric precursors. In detail, d would show how much the real maximum concentration is above the expected typical maximum concentration of a random anomaly distribution; while n value measures how much the largest concentration deviates with respect a typical random deviation: the larger are the d and n values, the more the results of the analysis applied to real data deviate from randomness. The best cases for which the real analyses are well distinct from random simulations are selected when d≥1.5, because the anomaly density is equal to or larger than 50% of random distribution, and n≥4, because the probability to be random is equal to or less than 0.1%.  This is the case of Y magnetic field component with a search in the Dobrovolsky area around each considered earthquake epicentre. The electron density is slightly less effective in the correlation with earthquakes, but still better than a homogeneous random distribution of anomalies.
Expert elicitation as tool for climate and hydrological model uncertainty reduction
Authors: Henriksen Hans Jørgen , Pasten-Zapata Ernesto , Berg Peter , Pimentel Rafael , Thirel Guillaume , Lira-Loarca Andrea , Photiadou Christiana
Published: March 2020

As part of the ERA-NET Cofund for Climate Service from JPI-Climate, Expert Elicitation (EE) has been investigated as a tool for uncertainty reduction in the research project AQUACLEW in European case studies. Results from the elicitation can be compared to quantitative approaches to determine whether we have the knowledge and skills to differentiate good-performing models from an ensemble of models. EE could thus be a potential method to refine the climate-impact production chain, in cases where a quantitative validation of the ensemble is not feasible. 
To implement the EE on selective case studies of AQUACLEW we have developed a framework of the procedure. This protocol is then used as training material by experts who are invited to a one-day workshop. In this document an introduction provides background information about the project including a short description of the five case studies involved in the elicitation. A subset of the EURO-CORDEX EUR-11 ensemble of climate models based on three General Circulation Models and four Regional Climate Models is described. Finally, the hydrological models used in three of the five case studies are described along with results on their skills to simulate the observations at the selected study sites. 
As an example, the Danish case study focuses on agricultural production in central Denmark. Climate change in the Danish case is expected to affect soil moisture and wetness conditions during winter and spring, where more precipitation is foreseen, and dryness during summer and early fall, where less precipitation is expected. More wetness/higher groundwater levels during winter and spring will adversely affect the farming field work in connection with sowing as well as crop growth on water logged fields leading to needs for increased drainage of fields. Dryer summers will adversely affect crop yield and lead to needs for increased irrigation. Hence both flooding and drought has been examined together with the resulting effect on the root zone moisture content, the groundwater level and the river discharge. Focus is given to uncertainty of the projections of future conditions which is a function of both emission scenario, choice of climate model and agro-hydrological model. 
The presentation will focus on the training material consisting of a structured, condensed text and comparable illustrations across case studies and selected modelling approaches. Results of the EE workshop held in March 2020 will be discussed with lessons learned and viability of the EE tool. 
Perspectives on the prediction of catastrophic slope failures from satellite InSAR
Authors: Raspini Federico , Carlà Tommaso , Intrieri Emanuele , Bardi Federica , Farina Paolo , Ferretti Alessandro , Colombo Davide , Novali Fabrizio , Casagli Nicola
Published: March 2020

In many landslide studies, the possibility to predict future behaviour is still a major concern. To date, early-warning systems have mostly relied on the availability of detailed, high-frequency data from sensors installed in situ. Methods deducing reliable failure predictions have been largely applied at local scale, where in situ monitoring systems can be installed.

The same purpose could not be chased through spaceborne monitoring applications, as these could not yield information acquired in sufficiently systematic fashion: the low data sampling frequency of most of the satellite systems hampered the possibility to retrieve the necessary details of tertiary creep characterized by accelerating deformation. So far, the lack of systematic information on ground displacement acquired at regional scale was another serious limit hampering the application of failure prediction methods at wide scale. Such limitations can be partially solved through the exploitation of new generation spaceborne platforms.

The launch of Sentinel-1 mission opened a new opportunity for InSAR monitoring applications thanks to the increased acquisition frequency, the regularity of acquisitions and the policy on data access. We demonstrate the potential of satellite Interferometric Synthetic Aperture Radar (InSAR) to identify precursors to catastrophic slope failures.

Here we present three sets of Sentinel-1 constellation images processed by means of multi-interferometric analysis. We detect clear trends of accelerating displacement prior to the catastrophic failure of three large slopes of very different nature: an open-pit mine slope, a natural rock slope in alpine terrain, and a tailings dam embankment. We determine that these events could have been located several days or weeks in advance. The results highlight that satellite InSAR may now be used to support decision making and enhance predictive ability for this type of hazard.
Emissions of methane from temperate artificial reservoirs – what is already known
Authors: Frouzova Jaroslava , Bašta Jan
Published: March 2020

Methane is assumed to belong to the most  important greenhouse gases, however factors affecting methane production and emission are still not satisfactory elucidated. Artificial reservoirs which are critical resources to obtain water and hydropover in many countries are  one of the methane sources which received only limited attention so far.   We reviewed existing information about methane emissions from them.  Emissions  are combination of diffusion, ebullition and degassing under dam, but not all pathway must be presented. Nineteen studies, mainly from North America and Europe were compared, Only small portion of the studies was focusing on all pathways of methane release. Spatio-temporal variability, which is especially high for ebullition (ebullition is probably responsible for the most of the methane emissions), was covered in 3 reservoirs only. For this purposes is newly used acoustical method good tool, hydroacoustics cover mainly spatial variability of ebullition, which is poorly couth by traditional bubble traps. The most of the  studies was performed in summer period only and for low number of localities.  Future studies should use more uniform design covering better all potential pathway of methane emissions and  taking care of spatio-temporal variability of ebullition.  More systematic studies covering effect of climate and landscape variables as well as reservoir properties (morphology management etc.) are needed.
New insights on the structural setting of the Pisciarelli fumarole field (Campi Flegrei caldera): implications for evolution and eruptive scenarios
Authors: Isaia Roberto , Di Giuseppe Maria Giulia , Natale Jacopo , Tramparulo Francesco D'Assisi , Troiano Antonio , Vitale Stefano
Published: March 2020

The Solfatara-Pisciarelli area, located in the active Campi Flegrei caldera (Italy) hosts an intense hydrothermal activity, whose shallower expression is controlled by a complex pattern of fractures and faults. Volcanological and structural studies may be the key to disclose the relationships between brittle structures and hydrothermal activity, as well as to understand the dynamic processes and possible eruption scenarios. For this purpose, we present the results of a volcanological and structural survey combined with Electrical Resistivity Tomography (ERT) and Self Potential data. Three ERT surveys has been performed in order to reconstruct the Pisciarelli structural setting and the relationships of the main fractures and faults with the underground fluid circulation. Two measured profiles crossing the main mud pool and fumaroles of Pisciarelli and has been repeated every three months to evaluate the possible influence of seasonal effects on the hydrothermal system. These profiles performed during the last year have been compared with a first ERT prospection carried on in correspondence of a 100 m long survey line, which crosses along the W-E direction the Pisciarelli permanent mud pool and its main fumarole. The comparison of the results with temperature, geochemical data and rainfall rates allowed to separate the areas dominated by seasonal effects from areas where deeper injected gasses cumulate in the subsoil. Further indication on the fluid circulation and structures derived by a mapping of the self-potential anomaly realized for the whole Solfatara-Pisciarelli area. The rocks exposed in the Pisciarelli area host a large number of faults and fractures, the latter often related to fault damage zones. Cross-cutting fault and fracture relationships and their relations with the volcanic sequences suggest that NW-SE and NE-SW trending faults are sealed by Solfatara deposits (4.28 ka); whereas E-W and N-S trending faults cross-cut the youngest volcanic succession (Astroni deposits, 4.25 ka). Several landslide deposits were recognized in the higher part of the Pisciarelli fumarole field, mainly due to intense rock fracturing, hydrothermal alteration, mud-pool activity and steep relieves surrounding the mud pool. Ancient landslide deposits overlying mud sediments, similar to those nowadays forming within the active mud pool, cropping out along the slope, at about 5 meters above the present mud pool level. New landslide phenomena could seal off the mud pool and fumaroles of Pisciarelli, with a possible consequence to trigger an hydrothermal explosions as described for other hydrothermal systems in the world.
The early origin of feathers
Authors: Benton Michael
Published: March 2020

Feathers are a diagnostic character of birds, and yet new fossils show they likely originated more than 100 million years before the first birds. In fact, feathers probably occurred in all dinosaur groups, and in their cousins, the pterosaurs, as we showed in 2019. This finding confirms current knowledge of the genomic regulation of feather development. Our work stems from ten years of collaboration with Chinese colleagues, during which we set ourselves the taks of understanding fossil feathers. Our first discovery was to answer the question, ‘Will we ever know the colour of dinosaurs?’. In 2010, we were able to announce the first objective evidence for colour in a dinosaur. Using ultrastructural studies of fossil feathers, we identified melanosomes for the first time in dinosaur feathers, and these demonstrated that Sinosauropteryx had ginger and white rings down its tail. Studies of other dinosaurs identified patterns of black, white, grey, brown, and ginger. This is part of a new wave in palaeobiology where we apply objective approaches to provide testable hypotheses, once thought impossible in the historical sciences.
Satellite Observations of Organizational Regimes in Low-Level Mixed-Phase Clouds over the Southern Ocean
Authors: Danker Jessica , Sourdeval Odran , McCoy Isabel L. , Wood Robert , Possner Anna
Published: March 2020

On average stratocumulus clouds cover about 23% of the ocean surface and are important for Earth’s radiative balance. They typically self-organize into cellular patterns and thus are often referred to as mesoscale-cellular convective (MCC) cloud systems. In the Southern Ocean (SO), low-level clouds cover between 20% to 40% of the ocean surface in the mid-latitudes where they exert a substantial radiative cooling. In a previous study, McCoy et al (2017) demonstrated that different MCC regimes may be associated with different cloud albedos and thus different cloud radiative forcing.
Many of the MCC clouds in the SO are not pure liquid but contain a mixture of liquid and ice. Here we investigate whether the formation of ice within these mixed-phase clouds influences MCC organization and thus the cloud-radiative effect.
To investigate the cloud phase we use the raDAR-liDAR (DARDAR) data product (version 1) from Cloud-Aerosol-Water-Radiation Interactions (ICARE) Data and Services Center which provides collocated data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), CloudSat and Moderate Resolution Imaging Spectroradiometer (MODIS). The “Simplified DARMASK Categorization Flag” of DARDAR is used to categorize the vertically resolved cloud phase into a single cloud phase per data point: clear, multi-layer, liquid, mixed or ice. In order to distinguish between open and
closed MCC regimes, we collocate the DARDAR product with an MCC classification data set from McCoy et al (2017) which is based on a neural network algorithm applied to MODIS Aqua data.
Our preliminary results confirm previous ground-based observations that most mixed-phase clouds are composed of a supercooled liquid top and ice underneath. Furthermore, our preliminary analysis suggests open MCCs occur more frequently as mixed-phase clouds (57% (DJF), 55% (JJA)) in the SO compared to liquid clouds (39% (DJF), 37% (JJA)) during both summer (DJF) and winter (JJA). In contrast, closed MCCs are more likely to appear as liquid clouds (58%) in comparison to mixed-phase clouds (40%) during winter, whereas during summer there seems to be no tendency for closed MCCs to be either liquid (51%) or mixed (49%).
Assessment of hydrogeochemical processes and geogenic mercury pollution in coastal karstic aquifers in semi-arid environments
Authors: Pouliaris Christos , Spyropoulou Alexandra , Sarris Ioannis , Laspidou Chrysi , Kallioras Andreas
Published: March 2020

Water resources management in coastal where the freshwater availability is limited has often led to rising concerns about the capability of local resources to cover the increased water needs. This condition is especially amplified in areas whereextra stress is added to the water sources from overexploitation and/or quality degradation.

The present study is located in the island of Skiathos, which is one of the Greek islands that are most popular to tourists. Throughout the long touristic period the population of the island is steeply increased resulting to an increase in water demand compared to the remaining months.The island is dealing with serious water supply issues since groundwaterquality is deteriorated due to aquifer salinization and Hg contamination, making the tap water not safe for drinking and other household uses for more than a decade.

Mercury concentration in water for domestic usage is monitored systematically, with values up to 6 μg/L (maximum permitted European limit for total mercury in the drinking water is 1 μg/L).The local water utility company, in order to cover the increased water demand, intensifies the pumping from the main well resulting to sea intrusion in the aquifer. Mercury is present in the rocks of Skiathos with the form of the mineral cinnabar (HgS) and although it is practically insoluble, the increase of chloride concentration due to aquifer salinization, shifts the reaction equilibrium towards mercury solubilization by complexation with chloride. Thus, mercury is released from the rocks to the groundwater entering later on the water supply network.

In order to face the twofold problem of groundwater salinization and mercury contamination the present study aims at defining a threshold for thevolume that is abstracted from the aquifer on a daily basis. The investigation involves the development of a groundwater flow model covering an area of approximately 13.3 km2 that is exploited for supplying the town of Skiathos with tap water. Information about the general hydrogeological conceptual model is derived from previous investigations in the area. The groundwater model achieves an optimizationof the groundwater pumping rates that prevent seawater from entering the aquifer and deteriorating the groundwater quality. Results show that a reduction of 27.2 % in the pumping rates, in combination with the already planned upgrade in the distribution networks, would prevent seawater from entering the aquifer and affecting groundwater reserves, while, at the same time, the need for tap water in the town of Skiathos is met.
Urban Thematic Exploitation Platform - supporting urban research with EO data processing, integrative data analysis and reporting
Authors: Bachofer Felix , Esch Thomas , Balhar Jakub , Boettcher Martin , Boissier Enguerran , Marconcini Mattia , Metz-Marconcini Annekatrin , Opletal Michal , Pacini Fabrizio , Soukup Tomas , Svaton Vaclav , Zeidler Julian
Published: March 2020

Urbanization is among the most relevant global trends that affects climate, environment, as well as health and socio-economic development of a majority of the global population. As such, it poses a major challenge for the current urban population and the well-being of the next generation. To understand how to take advantage of opportunities and properly mitigate to the negative impacts of this change, we need precise and up-to-date information of the urban areas. The Urban Thematic Exploitation Platform (UrbanTEP) is a collaborative system, which focuses on the processing of earth observation (EO) data and delivering multi-source information on trans-sectoral urban challenges.

The U-TEP is developed to provide end-to-end and ready-to-use solutions for a broad spectrum of users (service providers, experts and non-experts) to extract unique information/ indicators required for urban management and sustainability. Key components of the system are an open, web-based portal connected to distributed high-level computing infrastructures and providing key functionalities for

i) high-performance data access and processing,

ii) modular and generic state-of-the art pre-processing, analysis, and visualization,

iii) customized development and sharing of algorithms, products and services, and

iv) networking and communication.

The service and product portfolio provides access to the archives of Copernicus and Landsat missions, Datacube technology, DIAS processing environments, as well as premium products like the World Settlement Footprint (WSF). External service providers, as well as researchers can make use of on-demand processing of new data products and the possibility of developing and deploying new processors. The onboarding of service providers, developers and researchers is supported by the Network of Resources program of the European Space Agency (ESA) and the OCRE initiative of the European Commission.

In order to provide end-to-end solutions, the VISAT tool on UrbanTEP allows analyzing and visualizing project-related geospatial content and to develop storylines to enhance the transport of research output to customers and stakeholders effectively. Multiple visualizations (scopes) are already predefined. One available scope exemplary illustrates the exploitation of the WSF-Evolution dataset by analyzing the settlement and population development for South-East Asian countries from 1985 to 2015 in the context of the Sustainable Development Goal (SDG) 11.3.1 indicator. Other open scopes focus on urban green, functional urban areas, land-use and urban heat island modelling (e.g.).
Multifractality in Humanitarian Applications
Authors: Jenerowicz Małgorzata , Wawrzaszek Anna , Drzewiecki Wojciech , Krupiński Michał , Aleksandrowicz Sebastian
Published: March 2020

     Every year the total number of people who had been forcibly displaced (refugees, asylum seekers, and internally displaced persons) is constantly rising, a fact that is directly reflected in the area covered by IDP/refugee camps. Long-term humanitarian relief requires reliable and comprehensive information that is constantly delivered during a crisis. Very High Resolution (VHR) optical satellite data have been shown to be useful in monitoring IDP/refugee camps as it can provide an overview of the affected areas with a spatial resolution of up to 0.3 m within a matter of days.

     The aim of our research is to verify the usefulness of multifractal parameters as descriptors of IDP/refugee camps area, both in the context of their applicability and usability in the humanitarian related issues. In particular, we perform studies devoted to: (I) the complex terrain situation description with the division into compact and dispersed structures; and (II) the identification of IDP/refugee camps area extent aiming at distinguishing residential areas from other land use/land cover types. The analysis performed in two IDP/refugee camps, i.e. Ifo and Ifo 2 (Daadab) in Kenya and Al Geneina in Sudan, based on GeoEye-1 and Pléiades-1A VHR satellite data, gives a promising aspect of limited calculation time needed for the initial stage of image classification in respect to the spatial complexity of analysed terrain. Our results show that the degree of multifractality calculated for the selected images increases for compact areas with high-contrast structures (e.g., functional buildings and dwellings). Consequently, the extraction of the IDP/refugee camps extent by using only one feature, i.e., the degree of multifractality, proved to be an efficient way for initial image classification.

     We hope that our studies supplemented by further research, i.e. pre- and post-processing, the inclusion of multispectral bands, analyzing other areas of interest, and examining the added value of other multifractal measures, will help to develop an unsupervised classification approach providing results more quickly, with more frequent updates.

 

Research supported by the National Science Centre, Poland, under Grant 2016/23/B/ST10/01151.
Eoarchean formation of the Isua supracrustal belt
Authors: Webb A Alexander G , Müller Thomas , Zuo Jiawei , Haproff Peter , Ramírez-Salazar Anthony
Published: March 2020

A major shift in Earth’s crustal generation processes at ~3.2 to 2.5 Ga has been inferred from mineralogical, geological, and geochemical records, particularly those recorded by fine-grained sediments and zircon crystals. The most common hypothesis to explain this shift is the onset of plate tectonic recycling following some form of hot stagnant lid geodynamics. However, all prior detailed geologic studies of our best-preserved Eoarchean terrane, the ~3.85 - 3.60 Ga Isua supracrustal belt of SW Greenland, interpret this site to record terrane collision within the context of plate tectonics. This represents a significant counterweight to the assumption underpinning the ~3 Ga tectonic-mode-change models, i.e., the idea that early Earth’s record is broadly representative. The Isua belt is divided into ~3.8 and ~3.7 Ga halves, and these have been interpreted as plate fragments which collided by ~3.6 Ga. Here, we examine the evidence used to support plate tectonic interpretations, focusing on 1) reanalysis of prior geochronological results and associated cross-cutting relationships which have previously been interpreted to record as many as eight tectonic events, and 2) new field observations leading to reinterpretation of basic structural relationships. Simpler interpretations of the geochronological and deformation data are viable: the belt may have experienced nearly homogeneous metamorphic conditions and strain during a single deformation event prior to intrusion of ~3.5 Ga mafic dikes. Curtain and sheath folds occur at multiple scales throughout the belt, with the entire belt potentially representing Earth’s largest a-type fold. We propose a new model: two cycles of volcanic burial and resultant melting and TTG intrusion produced first the ~3.8 Ga rocks and then the ~3.7 Ga rocks above, after which the whole belt was deformed and thinned in a shear zone, producing the multi-scale a-type folding patterns. The Eoarchean assembly of the Isua supracrustal belt is therefore most simply explained by vertical-stacking volcanic and instrusive processes followed by a single shearing event. In combination with well-preserved Paleoarchean terranes, these rocks record the waning downward advection of lithosphere inherent in volcanism-dominated heat-pipe tectonic models for early Earth. These interpretations are consistent with recent findings that early crust-mantle dynamics are remarkably similar across the solar system’s terrestrial bodies.
Grasswise: monocultures or binary grass mixtures for African rangelands users?
Authors: Mganga Kevin , Nyariki Dickson , Bosma Luwieke , Kioko Theophilus , Kadenyi Nancy , van Steenbergen Frank
Published: March 2020

Reseeding, using drought tolerant indigenous perennial grasses is a viable option for combating rangeland degradation, provision of livestock feed and improving livelihoods of pastoral communities. However, debates on whether monocultures or binary grass mixtures establishments are best suited for African rangelands managers, are still ongoing. Our opinion and contribution to this debate is informed by results obtained from a combination of an ecological field based and socioeconomic study in a typical semi-arid rangeland in Kenya. Perennial forage grasses indigenous to African rangelands Cenchrus ciliaris (African foxtail grass), Enteropogon macrostachyus (Bush rye grass) and Eragrostis superba (Maasai love grass) were established as monocultures and binary grass mixtures. Binary grass mixtures demonstrated significantly higher rehabilitation indices for plant frequency, basal cover and plant densities and soil hydrological properties (infiltration capacity, runoff and sediment production). However, pastoral communities showed preference to monoculture than binary mixtures. This was attributed to their role in livestock production. In conclusion, considering the ecological and socio-economic value of African rangelands to pastoral communities, the choice of either monoculture or binary grass mixture establishment will primarily be informed by the principle objective(s) of the rangeland manager.    

 
Exploring a Variable-Resolution Modeling Approach within a Global Nonhydrostatic Dynamical Core
Authors: Zhou Yihui , Zhang Yi , Liu Zhuang , Li Jian , Yu Rucong
Published: March 2020

High-resolution numerical weather and climate models have a great advantage in both prediction and simulation for their ability to resolve small-scale systems, but suffer from expensive computational cost. The aim of this study is to explore a cost-effective variable-resolution modeling approach within a newly developed global nonhydrostatic dynamical core based on an unstructured mesh. We provide a size-controllable formulation of hierarchical refinement mode by an adapted density function for more realistic high-resolution simulations. The dynamical core is tested regarding both dry and moist atmosphere to evaluate variable-resolution simulations against quasi-uniform ones. In baroclinic wave tests, the variable-resolution model, which owns much less grid points, captures a comparable fine-scale fluid structure with the high-resolution quasi-uniform one in the refinement region. In the coarse region, the result of the variable-resolution simulation matches that of the low-resolution quasi-uniform one, which contributes to smaller global errors of the variable-resolution simulation. A series of sensitivity tests regarding parameters of the hierarchical refinement mode validate the high stability of the variable-resolution model to preserve the intensity and vertical structure of tropical cyclones moving through the transition zone. The variable-resolution modeling lays a strong foundation for potential improvement of regional high-resolution simulations.
The challenging research data management support in the interdisciplinary cluster of excellence CliCCS
Authors: Anders Ivonne , Lammert Andrea , Peters Karsten
Published: March 2020

In 2019 the Universität Hamburg was awarded funding for 4 clusters of excellence in the Excellence Strategy of the Federal and State Governments. One of these clusters funded by the German Research Foundation (DFG) is “CliCCS – Climate, Climatic Change, and Society”. The scientific objectives of CliCCS are achieved within three intertwined research themes, on the Sensitivity and Variability in the Climate System, Climate-Related Dynamics of Social Systems, and Sustainable Adaption Scenarios. Each theme is structured into multiple projects addressing sub-objectives of each theme. More than 200 researchers the Hamburg University, but also other connected research centers and partner institutions  are involved and almost all of them are using but mainly produce new data.

Research data is produced with great effort and is therefore one of the valuable assets of scientific institutions. It is part of good scientific practice to make research data freely accessible and available in the long term as a transparent basis for scientific statements.

Within the interdisciplinary cluster of excellence CliCCS, the type of research data is very different. The data range from results from physically dynamic ocean and atmosphere models, to measurement data in the coastal area, to survey and interview data in the field of sociology. 

The German Climate Computing Center (DKRZ) is taking care on the Research Data Management and supports the researchers in creating data management plans, keeping naming conventions or simply finding the optimal repository to publish the data. The goal is to store and long-term archiving of the data, but also to ensure the quality of the data and thus to facilitate potential reuse.