bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Rupture and Ground Motion Modeling of the 2016 M6.2 Amatrice and M6.5 Norcia, Central Italy, Earthquakes Constrained by Bayesian Dynamic Source Inversion
Authors: Taufiqurrahman Taufiq , Gabriel Alice-Agnes , Gallovic Frantisek , Valentova Lubica
Published: March 2020

The complex evolution of earthquake rupture during the 2016 Central Italy sequence and the uniquely dense seismological observations provide an opportunity to better understand the processes controlling earthquake dynamics, strong ground motion, and earthquake interaction. 

We here use fault initial stress and friction conditions constrained by a novel Bayesian dynamic source inversion as a starting point for high-resolution dynamic rupture scenarios. The best-fitting forward models are chosen out of ~106 highly efficient simulations restricted to a simple planar dipping fault. Such constrained, highly heterogeneous dynamic models fit strong motion data well. Utilizing the open-source SeisSol software (www.seissol.org), we then take into account non-planar (e.g., listric) fault geometries, inelastic off-fault damage rheology, free surface effects and topography which cannot be accounted for in the highly efficient dynamic source inversion. SeisSol is based on the discontinuous Galerkin method on unstructured tetrahedral meshes optimized for modern supercomputers. 

We investigate the effects of including the realistic modeling ingredients on rupture dynamics and strong ground motions up to 5 Hz. Synthetic PGV mapping reveals that specifically fault listricity decreases ground motion amplitudes by  ~50 percent in the extreme near field on the foot-wall. On the hanging-wall shaking is increased by ~150 percent as a consequence of wave-focusing effects within 10 km away from the fault. Dynamic modeling thus suggests that geometrical fault complexity is important for seismic hazard assessment adjacent to dipping faults but difficult to identify by kinematic source inversions.
Impact of blocking on low wind events and its representation by high-resolution GCMs: An energy perspective
Authors: Gonzalez Paula , Brayshaw David , Schiemann Reinhard
Published: March 2020

With higher penetration of renewable energies and the effort to decarbonize power production there is a strong interest in the objective characterization of wind resource. Over Europe, wind power accounts for around 17% of total power capacity and almost 30% of renewable capacity and is the overall second largest form of generation capacity after gas. 

In addition to the description of mean capacity factors, there is a need to characterize extremes. Low wind events and persistent low wind events (LWE) are of particular interest because during these the energy system needs to rely on ‘backup’ sources such as gas, coal and nuclear. Over the United Kingdom and other parts of Europe, these are often linked to the occurrence of blocking (e.g., Brayshaw et al. 2012, Cannon et al. 2015, Grams et al. 2017), which is the initial focus of this study. Additionally, blocking events have an impact on near-surface temperatures over Europe, which implies an effect in weather-dependent energy demand. 

This study focuses on the impacts of blocking conditions on low wind events and their persistence, and the representation of these effects on the high-resolution (around 25km) global PRIMAVERA models. Our results confirm that blocking events over Europe have a significant impact on the occurrence and duration of low wind speeds at the country level, which is of relevance to the energy sector. In addition to becoming more frequent, LWE are also more persistent under blocking conditions over large areas of Europe. Both effects are in general captured by most of the PRIMAVERA GCMs analysed here, revealing that when the models do get the blocking events, the basic dynamical connection with wind anomalies is present. Nonetheless, the fact that the simulated weather conditions have deficiencies introduces biases in the properties of the events and their joint occurrence.  

The errors in the models depend on the statistic, the country and the resolution, but some consistent bias patterns can be observed at times (e.g., North-South dipolar structures). No robust improvements in the representation of these effects were observed in the high-resolution versions of the PRIMAVERA models, nor where the highest resolution runs consistently outperforming coarser simulations.  

Blocking impacts to the energy systems are not only limited to wind power generation, since these large-scale anomalies also have an impact on near-surface temperature and therefore on electricity demand. These effects are also addressed here.
Representation of Northwest African upwelling in CMIP5 models
Authors: Castaño-Tierno Antonio , Rodríguez-Fonseca Belén , Mohino Elsa , Losada Teresa
Published: March 2020

The Northwest Africa (NWA) upwelling region is located along the Senegalese and Mauritanian coast, between 10°N and 25°N and in a very narrow longitudinal band. In this region, most of the upwelled waters are due to alongshore surface winds through Ekman pumping.

The rapid increase in the upper ocean upwelling in this region along the 20th century and the contradictions found about future projections put forward the need for a better understanding of model’s ability to simulate Ekman induced upwelling processes.

In this work we assess intermodel variability to better understand the causes of different responses and spread among a set of CMIIP5 models.  

Results suggest that the seasonal cycle of NWA upwelling is qualitatively well simulated by CMIP5 models, although models tend to show strong biases for the permanent upwelling latitudes (north of 20°N) and the seasonal upwelling area (around 15°N in boreal spring). The maximum vertical temperature gradient shown by CMIP5 models is higher than that of SODA reanalysis and prevents cold waters from deeper layers to reach the surface, thus making coastal upwelling less effective in affecting sea surface temperatures.

Most of the intermodel variance is explained by the two first EOF modes of intermodel variability. The first mode shows a latitudinal structure, with a maximum in the permanent upwelling season, while. the second one is more seasonal. Both modes are very related to changes in the North-West Africa land-sea surface pressure gradient. In the case of the leading mode, incoming solar radiation differences between the North African desert and the ocean are the cause of the pressure gradients. For the second mode pressure changes in the Atlantic Ocean are driven by ITCZ shifts in response to interhemispheric differential warming.
Decoding 3-D monazite textures using LA-ICP-MS raster mapping
Authors: Weller Owen , Jackson Simon , Miller William , St-Onge Marc , Rayner Nicole
Published: March 2020

Texturally complex monazite grains within two granulite-facies pelitic migmatites from southern Baffin Island, Arctic Canada, were mapped by laser ablation-inductively coupled plasma-mass spectrometry to quantitatively determine the spatial variation in trace element chemistry with a 4-5 μm resolution (with up to 1883 analyses per grain). The maps demarcate growth zones, some of which were cryptic with conventional imaging, highlighting the 3-D complexity of monazite grains that have experienced multiple episodes of growth and resorption during high-grade metamorphism. Associated monazite trace element systematics are highly variable, both within domains interpreted to have grown in a single event, and between samples that experienced similar metamorphic conditions and mineral assemblages. This result cautions against generalised petrological interpretations being made about monazite trace element signatures as it suggests sample-specific controls. Nevertheless, by quantifying monazite textures, a related U-Pb dataset is re-interpreted, allowing ages to be extracted from a continuum of concordant data. The results reveal a ~45 Myr interval between prograde metamorphism and retrograde melt crystallisation in the study region, emphasising the long-lived nature of heat flow in high-grade metamorphic terranes. Careful characterisation of monazite grains suggests that continuum-style U-Pb datasets can be decoded to provide insights into the rates of metamorphic processes.
The annual and diurnal cycles of precipitation over an Equatorial Andean valley and its transition to the Amazon Basin: A case at the Antizana region
Authors: Ruiz Jean Carlos , Espinoza Jhan Carlo , Junquas Clementine , Condom Thomas , Villacís Marcos , Ribstein Pierre , Le Moine Nicolas , Campozano Lenin , Vera Andrea , Muñoz Teresa , Maisincho Luis
Published: March 2020

The spatiotemporal variability of precipitation over the complex topography of the Andean equatorial regions has recently caught the attention of researchers thanks to improvements in monitoring networks, including high temporal resolution data. Using a set of 38 rain gauges at hourly time step spanning the 2014-2015 period, this work aims to characterize the annual and diurnal cycles over the upper parts of the Guayllabamba (Andean valley) and Napo (transition zone) basins (78.65°W-77.75°W and -0.8S-0°, land area of ~10000 km2). This region drains respectively to Pacific and Amazonian rivers and is of particular interest because the region provides over 30% of the domestic water demand of the city of Quito, and presents a high glacierized volcano, the Antizana.

The annual cycle is characterized through cluster analysis of monthly rainfall showing two groups of stations that respond to bimodal and unimodal seasonal regimes and corresponds to the local boundary between the Pacific and the Amazon basins. The bimodality presents higher rainfall occurring during March-April and October-November, on the other hand, the unimodality presents its maxima in June.

A careful analysis of the evolution of the diurnal cycle during the year is done and results show that stations with bimodal annual regime peaks around 13:00-17:00 LT and in some months a second peak appears around 22:00-06:00 LT. Regarding stations with unimodal annual regime, the diurnal cycle peaks around 10:00 LT-18:00 LT and in addition shifts to 00:00-06:00 LT during June-August.

In general, the annual and diurnal cycles are useful for water management in the study zone, especially with regards to Quito’s water supply. Furthermore, the annual cycle and its relationship with altitude provides new information related to strong and weak precipitation gradients that are useful for hydro-glaciological modelling exercises. And the information on the diurnal cycle can improve some water management practices.
Role of kinetics on the couplings between fluid flow, deformation and reaction
Authors: Malvoisin Benjamin , Podladchikov Yury Y.
Published: March 2020

Short timescale processes such as earthquakes, tremors and slow slip events may be influenced by reactions, which are known to proceed rapidly in the presence of water (typically several days). Here, we developed a theoretical framework to introduce the influence of mineralogical reactions on fluid flow and deformation. The classical formalism for dissolution/precipitation reactions is used to consider the influence of the distance from equilibrium and of temperature on the reaction rate and a dependence on porosity is introduced to model the evolution of the reacting surface area during reaction. The thermodynamic admissibility of the derived equations is checked and an analytical solution is derived to test the model. The fitting of experimental data for three reactions typically occurring in metamorphic systems (serpentine dehydration, muscovite dehydration and calcite decarbonation) indicates a systematic faster kinetics on the dehydration side than on the hydration side close from equilibrium. This effect is amplified through the porosity term in the reaction rate. Numerical modelling indicates that this difference in reaction rate close from equilibrium plays a key role in microtextures formation during dehydration in metamorphic systems. The developed model can be used in a wide variety of geological systems where couplings between reaction, deformation and fluid flow have to be considered.
Estimation of Carbon Dioxide emissions along an active fault by using geoelectrical measurements
Authors: Piegari Ester , Di Maio Rosa , Salone Rosanna , De Paola Claudio
Published: March 2020

In the last twenty years, a growing interest is noticed in quantifying non-volcanic degassing, which could represent a significant input of CO2 into the atmosphere. Large emissions of non-volcanic carbon dioxide usually take place in seismically active zones, where the existence of a positive spatial correlation between gas discharges and extensional tectonic regimes has been confirmed by seismic data. Extensional stress plays a key role in creating pathways for the rising of gases at micro- and macro-scales, increasing the rock permeability and connecting the deep crust to the earth surface. Geoelectrical investigations, which are very sensitive to permeability changes, provide accurate volumetric reconstructions of the physical properties of the rocks and, therefore, are fundamental not only for the definition of the seismic-active zone geometry, but also for understanding the processes that govern the flow of fluids along the damage zone. In this framework, we present the results of an integrated approach where geoelectrical and passive seismic data are used to construct a 3D geological model, whose simulated temporal evolution allowed the estimation of CO2 flux along an active fault in the area of Matese Ridge (Southern Apennines, Italy). By varying the geometry of the source system and the permeability values of the damage zone, characteristic times for the upward migration of CO2 through a thick layer of silts and clays have been estimated and CO2 fluxes comparable with the observed values in the investigated area have been predicted. These findings are promising for gas hazard, as they suggest that numerical simulations of different CO2 degassing scenarios could forecast possible critical variations in the amount of CO2 emitted near the fault.
Early warning signals before paroxysmal activity at Stromboli volcano, Italy
Authors: Di Lieto Bellina , Romano Pierdomenico , Scarpa Roberto , Linde Alan T. , Sangianantoni Agata
Published: March 2020

Mt. Stromboli is an active volcano, located near the coasts of Sicily (Italy), in the Mediterranean Sea. Its volcanic activity is characterized by mild and frequent explosions, sometimes interrupted by occasional episodes of more vigorous activity, which can be accompanied by lava flows and more energetic eruptions, known as “major” or “paroxysmal” eruptions, according to the energy dissipated during the event.

Stromboli produced vulcanian eruptions in 2003, 2007 and July-August 2019, which were well recorded by the INGV monitoring network. In particular the last three events are studied through records from borehole strainmeters, which allow us to infer many details of source dynamics. These events are clearly preceded by a slow strain buildup, starting several minutes before the paroxysms, which can be used in future for civil protection purposes. The eruptions then consist of two or more pulses, with oscillations ranging from several seconds, as in 2007, to some minutes, such as in 2019 and lasting from several minutes to one hour after the explosions.

Mechanisms involved in the triggering process of the vulcanian explosions include an increase of magma flux ascending from sources located from 2 to 5-7 km depths and morphological complexity in the upper feeding system.

A preliminary early-warning algorithm, based on an evaluation of strain rate change, has been defined: it has shown itself capable of ascertain the occurring eruptions minutes before their summit onset.

Valuable information are embedded in the data used in the current work, which could be used not only for scientific purposes but also from civil protection for monitoring reasons. Such a variety of possible usage needs the setting of principles and legal arrangements to be implemented in order to ensure that data will be properly and ethically managed and in turn can be used and accessed from the scientific community.

Particular care is needed in order to harmonize the different rules regarding use of data/information, to identify any potential legal issues related to Intellectual Property (IP) and to set up clear and consistent principles related to IP Rights.
From remote sensing to bioeconomy: how big data can improve automatic map generation
Authors: Rizzi Jonathan , Nystuen Ingvild , Debella-Gilo Misganu , Søvde Nils Egil
Published: March 2020

Recent years are experiencing an exponential increase of remote sensing datasets coming from different sources (satellites, airplanes, UAVs) at different resolutions (up to few cm) based on different sensors (single bands sensors, hyperspectral cameras, LIDAR, …). At the same time, IT developments are allowing for the storage of very large datasets (up to Petabytes) and their efficient processing (through HPC, distributed computing, use of GPUs). This allowed for the development and diffusion of many libraries and packages implementing machine learning algorithm in a very efficient way. It has become therefor possible to use machine learning (including deep learning methods such as convolutional neural networks) to spatial datasets with the aim of increase the level of automaticity of the creation of new maps or the update of existing maps. 

Within this context, the Norwegian Institute of Bioeconomy Research (NIBIO), has started a project to test and apply big data methods and tools to support research activity transversally across its divisions.  NIBIO is a research-based knowledge institution that utilizes its expertise and professional breadth for the development of the bioeconomy in Norway. Its social mission entails a national responsibility in the bioeconomy sector, focusing on several societal challenges including: i) Climate (emission reductions, carbon uptake and climate adaptation); ii) Sustainability (environment, resource management and production within nature and society's tolerance limits); iii) Transformation (circular economy, resource efficient production systems, innovation and technology development); iv) food; and v) economy.

The presentation will show obtained results focus on land cover mapping using different methods and different dataset, include satellite images and airborne hyperspectral images. Further, the presentation will focus related on the criticalities related to automatic mapping from remote sensing dataset and importance of the availability of large training datasets.
Trends and projections in ice sheet mass balance
Authors: Shepherd Andrew ,   The IMBIE Team
Published: March 2020

In recent decades, the Antarctic and Greenland Ice Sheets have been major contributors to global sea-level rise and are expected to be so in the future. Although increases in glacier flow and surface melting have been driven by oceanic and atmospheric warming, the degree and trajectory of today’s imbalance remain uncertain. Here we compare and combine 26 individual satellite records of changes in polar ice sheet volume, flow and gravitational potential to produce a reconciled estimate of their mass balance. Since the early 1990’s, ice losses from Antarctica and Greenland have caused global sea-levels to rise by 18.4 millimetres, on average, and there has been a sixfold increase in the volume of ice loss over time. Of this total, 41 % (7.6 millimetres) originates from Antarctica and 59 % (10.8 millimetres) is from Greenland. In this presentation, we compare our reconciled estimates of Antarctic and Greenland ice sheet mass change to IPCC projection of sea level rise to assess the model skill in predicting changes in ice dynamics and surface mass balance.  Cumulative ice losses from both ice sheets have been close to the IPCC’s predicted rates for their high-end climate warming scenario, which forecast an additional 170 millimetres of global sea-level rise by 2100 when compared to their central estimate.
Enhancing geodiversity in the Matese Regional Park (Southern italy) using DPSIR model
Authors: Magliulo Paolo , Russo Filippo , Valente Alessio
Published: March 2020

The Matese Regional Park included the northern part of Campania and the southern part of Molise regions. The total area is about 33,000 ha. The institution of the Park was due to its extreme naturalistic and environmental richness, representative of the whole Southern Apennines chain. Unfortunately, the Park institution was not fully understood by local authorities and population as a development opportunity (touristic, agricultural, etc.).

Most of the area consists of an imposing calcareous massif, whose features are still completely natural. In some outcrops of Mesozoic limestone, exceptional fossils were found, among which the dinosaur cub Scipioniyx samntiyicus, popularly known as “Ciro”, is mentioned for importance, as it is recognized and studied all over the world for its excellent state of conservation. In addition to this unique specimen, a myriad of remains of fishes, reptiles, amphibians and rudists were found. To the threat of vandalism perpetrated in early years, the authorities responded by guaranteeing the conservation of the sites and fossils, but also by creating a place to welcome scholars and researchers. Thus, the Paleolab was born, i.e. a multimedial museum of geology and palaeontology with an increasing number of visitors.

The widespread diffusion of karst phenomena, both epigean and hypogean, contributed to fuel an underground water circulation, which is important for both quantity and quality. This resource was exploited over time, not only at the basal springs, but also locally, for domestic, agricultural and livestock uses and even for energy production. Therefore, the pressures on this resource are important and need a care planning. Moreover, contaminations by anthropogenic activities are possible, even if limited to some marginal areas, and are not coherent with the rules of a protected area.

Earthquakes could upset both the beauty of the Matese landscapes and the local activities. In fact, this area is one of the most seismogenetic ones in Southern Apennines. In historical epoch, several seismic events caused casualties and huge damages to the local settlements and even changed the physical features of the territory. However, the answers to these events became an opportunity, as they allowed both reconstructing less vulnerable buildings and the restitution of the typicality of some ancient settlements. A difficulty is nowadays represented by the alert systems, which are weak due to the articulated morphology and the accentuated dispersion of the buildings (residence and working sites).

In this contribution, several indicators were considered to describe the environmental situation of the Matese Park in the framework of a model able to identify the cause-effect relationships and the response that were put in place to obtain a change in the desired direction.
Environmental change effects on canopy water fluxes of a tropical mountain rain forest in the Andes of Ecuador
Authors: Bendix Jörg , Limberger Oliver , Pucha-Cofrep Franz
Published: March 2020

The tropical mountain forest (TMF) in the Andes of SE-Ecuador is globally one of the hottest hotspots of biodiversity. However, biodiversity and ecosystem services are threatened by environmental changes (climate and land use changes). This particularly holds for the mountain rain forest in the river valley of the Rio San Francisco between Loja and Zamora (Ecuador), where ecosystem water and carbon regulation are important services, expected to be especially affected adversely. An interdisciplinary team of Geo-, Bioscientists and researchers from socio-economy have investigated environmental change impacts on ecosystem water services over the last two decades in this area. Particularly changes in canopy water fluxes due to environmental change are one major objective of the ongoing research unit RESPECT (Environmental changes in biodiversity hotspot ecosystems of South Ecuador: RESPonse and feedback effECTs). In the talk, a general overview on environmental change impacts on canopy water fluxes derived from field measurements such as Eddy Covariance and Remote Sensing are presented. To look into future developments, well-adopted Land Surface Models (LSM) are required including suitable plant functional types (PFTs) and focal ecological processes, properly adapted to the complexity of the TMF. In the second part of the talk, the concept and first results of a new way of LSM modelling will be presented. The integrated concept will be finally used to unveil the resistance of the two ecosystem services against future climate change under different land use scenarios.  
High frequency water isotopes records during glacial/interglacial cycles on EPICA Dome C ice core.
Authors: Grisart antoine , Vinther Bo , Gkinis vasileos , Popp Trevor , Stenni Barbara , Pol Katy , Masson Delmotte Valerie , Jouzel Jean , Casado Mathieu , Laepple Thomas , Horhold Maria , Prie Frederic , Minster Benedicte , Fourre Elise , Landais Amaelle
Published: March 2020

The iconic curve of D in water showing the 8 glacial/interglacial cycles from the EPICA Dome C ice
core is now a reference in paleoclimate. It shows past temperature variability back to 800 ka over the
3200 m deep ice core with a 55 cm resolution. However, the millennial and centennial scale
variability gets more challenging to observe in the deepest part of the core. Indeed, the time
resolution worsens when going deeper in the ice because of the ice thinning: it is larger than 200
years at 2500 m depth. Furthermore, isotopic diffusion affects the signal at the bottom of the ice
core. Pol et al., (2010) have thus shown that the sub-millennial MIS (Marine Isotopic Stage) 19 signal
(3157-3181 m deep) is erased because of diffusion and high resolution doesn’t add any further
information at this depth. In this study we want to better characterize the increase of the isotopic
diffusion with depth by providing new high resolution water isotopes at several intervals over the
EPICA ice core (EDC).
We present here published high resolution (11 cm) d18O measurements over the EDC ice core as
well as new records of high resolution (11 cm) D over MIS 7;13 and 14). We use spectral analyses to
determine at which depth the isotopic diffusion erases the sub-millennial variability. We also show
that cold periods exhibit a larger variability of water isotopes than interglacial periods.
The information obtained here is crucial for the new project Beyond EPICA oldest ice core, which has
the goal of analyzing a 1.5 Ma old ice core. In the deepest part, 1 m of ice core could represent
10 000 years of climate archive.
Future water availability in West Africa: Estimates from high-resolution RCM modeling and multivariate bias correction
Authors: Dieng Diarra , Hald Cornelius , Laux Patrick , Lorenz Christof , Kunstmann Harald
Published: March 2020

Future water availability in West Africa: Estimates from high-resolution RCM modeling and multivariate bias correction

Diarra Dieng1, Cornelius Hald1, Patrick Laux1,2, Christof Lorenz1, Harald Kunstmann1,2

1Institute of Meteorology and Climate Research (IMK-IFU), Campus Alpine, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany,

2Institute of Geography, University of Augsburg, Augsburg, Germany,

 

With a wide range of ecological, climatic, and cultural diversities, West Africa is a rapidly developing region whose agricultural systems remain largely rain-fed and underdeveloped. In this study we examine the potential impacts of climate variability and climate change on the water availability in the mid-21st century in West  Africa by using high resolution simulations (12km) from the Weather and Research Forecasting (WRF) model and the COSMO-Climate Limited area Modelling (CCLM) for the RCP 4.5 scenario. Our approach is based on the simplified Penman-Monteith (PM) equation for daily ET, which requires the joint information on relative humidity, maximum and minimum daily temperatures, dew point temperature, solar radiation and wind speed. It is not only crucial that the statistical behavior of these modelled variables is close to observations, but also that the interplay between these variables is realistic. We therefore further adapted, applied and analyzed a subsequent bias-correction method for the WRF and CCLM simulations using a nonparametric, trend-preserving quantile mapping approach and a multivariate bias correction approach (MBCn). We present the details of the method and the derived implications for expected water availability in West Africa.
Postglacial zonation of soil organic matter in clayey till sediments
Authors: Ernstsen Vibeke
Published: March 2020

Studies of the distribution of soil organic matter (SOM) below intensively cultivated fields on clayey sediments of Quaternary age in Denmark show three markedly different zones from the surface and down to about 10 meters below surface. Each zone reflects the balance between input and losses of since the last glaciation.

The upper zone makes up the uppermost few meters below the soil surface. Here, the inherited bioavailable pool of SOM has mineralized and only small amounts of not-bioavailable SOM are present. The largest pool of SOM is renewable and derives from crops grown in the field.

In the underlying middle zone, the content of inherited SOM is very low and seems well protected against biological decomposition (not-bioavailable). No renewable source of SOM from the crops seems to reach down to this middle zone.

In the third and deepest zone, only inherited SOM is present. The SOM origins from the sediments deposited during the last glaciation, about 12,000 years ago.

Typically, the lowest contents of SOM is in the middle zone.

Zonation by content, composition, and bioavailability of the organic matter in soils and deeper sediments is important for the fate of many environmentally substances and for the quality of soil water as well of the quality of other parts of the aquatic environment. In addition, the SOM- pools of different composition in the three zones will most likely behave different to future changes in atmospheric CO2 and climate change adoption.
Dynamic topography controls on source-to-sink systems: Example of the last 40 Ma in South Africa.
Authors: Mallard Claire , Salles Tristan , Zahirovic Sabin , Ding Xuesong
Published: March 2020

Over deep time, mantle flow-induced dynamic topography drives deposition moderated by higher-frequency fluctuations in climate and sea level. The effects of deep mantle convection impact all the segment of the source to sink systems at different wavelengths and over various scales which remains poorly quantified. Field observations and numerical investigations suggest that the long-term stratigraphic record along continental margins contains essential clues on the interactions between dynamic topography and surface processes. However, it remains challenging to isolate the fingerprints of dynamic topography in the geological record.

We use the open-source surface evolution code Badlands (badlands.readthedocs.io), to quantify the impact of different timings and wavelengths of dynamic topography migration on the South African landscape responses.

We test three different dynamic topography scenarios obtained by both backwards advection and forwards modelling of mantle flow. We investigate their influence on landscape dynamics, stratal geometries and depositional patterns of South Africa over the past 40 Ma. We compare the evolution of the drainage organization, sediments flux, and stratigraphy obtained with the models with seismic, geochronological, and thermochronological data. We demonstrate that inland incision, spatial sediment accumulation, and depocenter migration strongly depend on the direction of sediment transport relative to the direction of dynamic topography propagation. It allows to identify realistic evolutions of mantle flow associated with the South African uplift history. Our results suggest that our source-to-sink numerical workflow can be used to explore, in a systematic way, the interplay between dynamic topography and surface processes and can provide insights into recognizing the geomorphic and stratigraphic signals of dynamic topography in the geological record.
Bayesian Parameter Estimation to Bivariate Drought Regional Frequency Analysis Model: Application to Han-River Watershed
Authors: Kim Ho Jun , Kim Jin-Guk , Cho He Mie , Kwon Hyun-Han
Published: March 2020

Copula-based bivariate drought frequency analysis has been widely employed to evaluate drought risk in the context of point frequency analysis. However, the relatively significant uncertainties in the parameters are problematic when available data are limited. This study developed a bivariate regional frequency analysis model using Copula function within the Bayesian modeling framework. An experimental study is first performed to assure ourselves whether the proposed model can accurately reproduce drought characteristics. The proposed model is capable of effectively representing the recent drought events and can provide drought risk information along with its uncertainty. The results confirm that the proposed model is not only effectively representing correlation with regional dependencies of drought, but also providing the uncertainty of parameters.

 

KEYWORDS: Copula, Bayesian, Bivariate drought regional frequency analysis, Uncertainty

 

Acknowledgement

This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMI 2018-07010.
Comparison of coupling methods in joint inversion along the Namibian continental margin
Authors: Franz Gesa , Moorkamp Max , Jegen Marion , Berndt Christian , Rabbel Wolfgang
Published: March 2020

Understanding the driving mechanisms of continental breakup is still a key question in global geodynamics. The Namibian continental margin and Walvis Ridge offer an ideal area for related studies, because it accumulates on- and offshore magmatic features, associated with crustal stretching, a potential plume impact, and continental breakup.

 

While previous studies in the area all agree on the general occurrence of these features, they have shown some contradictory results for their extent and depth. Therefore, we jointly invert different geophysical data sets to gain a deeper, three-dimensional insight into the continent-ocean-transition zone. In this study, we test three different cross-gradient coupling approaches for Magnetotelluric, Gravity and Seismic data sets or models. First, a fixed 3D density model is used as a structural constraint to MT data inversion. It’s impact is limited, due to large model areas with constant density values, and thus zero density gradients. Second, satellite gravity and MT data are jointly inverted. Both data sets reach a satisfactory misfit and the gravity data constraint slightly modifies the interpreted earth model. Third, a fixed 2D velocity model is used as a structural constraint for a 3D MT data inversion. Some assumptions had to be made to account for the dimensionality difference, but a sufficiently good data fit was achieved, and inversion benefits from a gradient structural model for the cross-gradient coupling. Earth model modifications through this velocity model constraint resemble the results from the joint Gravity-MT data inversion. The analysis of the three approaches, yields new insights into the cross-gradient coupling concept for joint inversion.

 

Interpreting these three earth models, we believe, that continental break-up in the South Atlantic is neither driven solely by a large plume, nor by pure tectonic forces. High resistivites, velocities and densities in the lower crust point to an accumulation of plume material. However, the size of these features is not big enough to explain the Gondawana break-up as a result of a mega-plume arrival. Indications for a tectonically driven break-up initiation include evidence for extensive crustal stretching, and often an abrupt change to oceanic regime, with the upwelling asthenosphere in juxtaposition to the stretched continental lithosphere. As our models indicate a broader transitional zone, we exclude a pure tectonically driven continental break-up. Our favoured explanation incorporates aspects of both hypothesis, where an accumulation of so-called secondary plumes initiate rifting and break-up. These would be smaller plumes, rising from mid-mantle depths, which might have a common source in the deep mantle.
On associating significance levels with temporal changes in empirical orthogonal function analysis: a case study for ENSO
Authors: Drotos Gabor
Published: March 2020

The availability of a large ensemble enables one to evaluate empirical orthogonal functions (EOFs) with respect to the ensemble without relying on temporal variability at all. Variability across the ensemble at any given time is supposed to represent the most relevant probability distribution for climate-related studies, and this distribution is presumably subject to temporal changes in the presence of time-dependent forcing. Such changes may be observable in spatial patterns of ensemble-based EOFs and associated eigenvalues. Unfortunately, estimates of these changes come with a considerable error due to the finite size of the ensemble, so that associating a significance level with the presence of a change (with respect to a null hypothesis about the absence of any change) should be the first step of analyzing the time evolution.

It turns out, however, that the conditions for the applicability of usual hypothesis tests about stationarity are not satisfied for the above-mentioned quantities. What proves to be feasible is to estimate an upper bound on the significance level for nonstationarity. This means that the true significance level would ideally be lower or equal to what is estimated, which would prevent unjustified confidence in the detection of nonstationarity (i.e., falsely rejecting the null hypothesis could not become more probable than claimed). Most importantly, one would avoid seriously overconfident conclusions about the sign of the change in this way. Notwithstanding, the estimate for the upper bound on the significance level is also affected by the finite number of the ensemble members. It nevertheless becomes more and more precise for increasing ensemble size and may serve as a first guidance for currently available ensemble sizes.

The details of the estimation are presented in the example of the EOF-based analysis of the El Niño–Southern Oscillation (ENSO) as it appears in the historical and RCP8.5 simulations of the Max Planck Institute Grand Ensemble. A comparison between results including and excluding ensemble members initialized with an incomplete spinup in system components with a long time scale is also given.
Particle displacement due to splash - analysis based on glass bead deposits
Authors: Mazur Rafał , Ryżak Magdalena , Sochan Agata , Marciszuk Karolina , Beczek Michał , Lamorski Krzysztof , Bieganowski Andrzej
Published: March 2020

Splash, which is the first stage of the water erosion, is a dynamic and complex phenomenon. The ejection of soil particles occurs within fractions of a second after the impact of a drop. The diameter of the deformation formed on the surface can be measured in millimeters. The complicated nature of the phenomenon necessitates the use of advanced equipment (high-speed cameras or surface scanners) and models for simplification of the subject of the study to analyze selected aspects of the splash.

The work presents the results of research in which glass beads were used as a soil model. The aim of the experiments was to determine the influence of the initial position of the deposit elements on their displacement as a result of a droplet impact.

A water drop with a diameter of 4.2 mm falling freely from a height of 1.5 m was used in the study. The beds were placed in aluminum rings with a diameter of 40 mm. The measurements were based on the initial and final position of the beads used as markers; these beads differed in color from the rest of the deposit. The source of data included pictures taken with a digital camera before and after the impact and control recordings made with high-speed cameras to correct possible errors. Additionally, some of the samples were scanned with a microtomograph, which allowed characterizing the surface deformation. Taking into account their structure, the beds used in the measurements were divided into two groups. The first one was used to analyze the influence of drops on individual elements - symmetrical patterns from colored beads were prepared on the sample surface; the second group was used to analyze the influence of drops on groups of elements - layers of beads with the same color were prepared on the surface of these samples.

Based on the experiment results, the movement of the deposit elements was divided into three types: displacement inside the area wetted by a drop, ejection, and placement on the crater rim. The initial location of the beads displaced over the greatest distances was a narrow ring covering the area from 4 to 8 mm from the point of the drop impact. It is worth noting that this area was associated with strong surface deformation. The use of "monolayers" helped to indicate that 97% of the beads ejected outside the ring with the deposit originated from the bed surface layer.

References

Mazur R., Ryżak M., Sochan A., Marciszuk K., Beczek M., Lamorski K., Bieganowski A., 2020. Surface deformation and displacement of bed elements during splash – Model tests. Catena 185, 104277

The study was partially funded from the National Science Centre, Poland in the frame of project no. 2014/14/E/ST10/00851.
Distinct Orogenic Processes in the South- and North-Central Tien Shan from Receiver Functions
Authors: Bao Xuewei , Zhang Bingfeng , Xu Yixian
Published: March 2020

Uplifting mechanisms for the Tien Shan, an active intracontinental orogenic belt, have been under debate for decades, a key issue being how the convergence has been accommodated at depth. Here we investigate the Moho structure across the central Tien Shan by common-conversion-point imaging and H-k-c stacking of receiver functions from a dense array. The observed Moho exhibits distinct characteristics among sub-blocks. Southward-dipping diffuse Moho is imaged in the Southern Tien Shan (STS), in contrast with the relatively flat and sharp Moho beneath the Tarim Basin. This feature along with the large Moho offset beneath the South-Boundary Fault suggests that the shortening and thickening of Tien Shan crust rather than the underthrusting of the Tarim Basin are responsible for the uplift of the STS. In the Northern Tien Shan, however, the imaged Moho doublet provides direct evidence for the underthrusting of the Kazakh Shield accommodating the convergence there.
Nature and origin of gas trapped in sediments in the Tagus River ebb-delta, off Lisbon, Portugal, the TAGUSGAS project
Authors: Ribeiro Carlos , Terrinha Pedro , Rosa Marcos , Neres Marta , Noiva João , Brito Pedro , Magalhães Vítor
Published: March 2020

The Tagus River ebb-delta is located near an important city center off Lisbon, Portugal. The Tagus delta hosts various kilometer scale landslides, the most important of which has been mapped and described with a presumable age of ~11 ky and 10 km in length, 4 km wide and 20 m of maximum thickness. An equivalent area of gas trapped in the sediments has also been reported (Terrinha et al., 2019).

The TAGUSGAS project aims at characterizing the nature and source of the gas. A multibeam and backscatter survey was carried out recently covering an area of 44 km2. Several morphologic artifacts were found. The magnetic survey carried out simultaneously allows at discriminating the anthropogenic origin of some of these artifacts. It also allows at distinguishing gas and igneous rock sources of acoustic blanking in the seismic reflection record.

The multibeam and backscatter basemap also serves as a tool to decide targets for seafloor sites for sample collection.

The authors would like to acknowledge the FCT financial support through project UIDB/50019/2020 – IDL and TAGUSGAS project (PTDC/CTA-GEO/31885/2017).
An investigation into the influence of high-resolution land-surface heterogeneity on atmospheric dynamics
Authors: Simon Jason , Ghannam Khaled , Katul Gabriel , Dirmeyer Paul , Findell Kirsten , Santanello Joseph , Chaney Nathaniel
Published: March 2020

Land-surface heterogeneity is known to play an important role in land surface hydrology and thus the boundary conditions for numerical weather prediction (NWP) and climate modeling. For this reason, there have been considerable efforts over the past two decades to improve its representation in large scale models. However, to date, the inclusion of sub-grid heterogeneity in modeling land-atmosphere interactions in regional and global models has been limited to sub-grid spatial means and thus have almost entirely disregarded its multi-scale impact on the simulated atmospheric dynamics. To begin to address this challenge, here we use large-eddy simulations (LES) coupled to a land-surface model to gain a more complete understanding of its role in the coupled land-atmosphere system. In this work, we illustrate its impact over the Southern Great Plains (SGP) site in the United States and present a path forward for using these modeling experiments to guide the development of a complementary coupling parameterization within climate models.

More specifically, over the SGP site, we use high-resolution LES to investigate the impact of SGS land heterogeneity under different atmospheric and surface conditions to inform the development of land-surface and planetary boundary layer (PBL) parameterizations for coarser, operational-scale weather and climate modeling efforts. The experiment methodology uses a high-resolution land-surface model (WRF-Hydro), spun-up over multiple years using reanalysis data, which is then coupled to the Weather Research and Forecasting (WRF) model for high-resolution LES. Cases are considered using both the fully heterogeneous land model as well as using a homogeneous surface with domain-averaged flux values at all grid points, allowing the dynamical effects of land-surface heterogeneity on the atmosphere to be isolated, and the land/atmospheric conditions under which land-surface heterogeneity plays a role to be studied. Results are evaluated primarily by the differences in the development of the planetary boundary layer and the extent, duration and intensity of developing rainfall events.
Nanoscale imaging at the calcite-water interface: Implications for potential environmental remediation.
Authors: Putnis Christine V.
Published: March 2020

Advanced imaging techniques such as atomic force microscopy (AFM) allow for direct observations of reactions at mineral surfaces at the nanoscale. This enables reaction mechanisms to be clarified. Aqueous solutions passing over a calcite surface often control coupled reactions of dissolution and precipitation, whereby calcite is replaced pseudomorphically by a more stable phase that precipitates at the calcite-fluid interface. Both molar volume changes as well as solubility changes between parent and product phases most commonly result in a concomitant porosity that then allows the solution to penetrate within the calcite. In this way pollutant elements such as phosphate, from over fertilization of agricultural soils, or water contaminated with elements such as, selenium, arsenic, antimony, chromium (from both natural and anthropogenic sources), can be sequestered within more stable, less soluble phases. Calcium carbonate barriers (such as crushed limestone) within water channels may present an effective and simple method to remove contaminant elements from water systems.