bluuebunny/crossref_metadata_2025 huggingface dataset:
How to Tailor my Process-based Hydrological Model? Dynamic Identifiability Analysis of Flexible Model Structures
Authors: Bronstert Axel , Pilz Tobias , Francke Till , Baroni Gabriele
Published: March 2020

In the field of hydrological modeling, many alternative mathematical representations of natural processes exist. To choose specific process formulations when building a hydrological model is therefore associated with a high degree of ambiguity and subjectivity. Identifiability analysis may provide guidance by constraining the a priori range of alternatives based on observations. In this work, a flexible simulation environment is used to build a process-based hydrological model with alternative process representations, numerical integration schemes, and model parametrizations in an integrated manner. The flexible simulation environment is coupled with an approach for dynamic identifiability analysis. The objective is to investigate the applicability of the coupled framework to identify the most adequate model structure. It turned out that identifiability of model structure varies in space and time, driven by the meteorological and hydrological characteristics of the study area. Moreover, the most accurate numerical solver is often not the best performing solution. This is possibly influenced by correlation and compensation effects among process representation, numerical solver, and parametrization. Overall, the proposed coupled framework proved to be applicable for the identification of adequate process-based model structures and is therefore a useful diagnostic tool for model building and hypotheses testing.
State of the scientific and technical knowledge about limiting temperatures in the Repository Site Selection process of Germany with simultaneous consideration to Europe and other European repository concepts
Authors: Maurer-Rurack Ute , Liebscher Axel , Magri Fabien
Published: March 2020

The Federal Republic of Germany has decided to dispose its high-level radioactive waste in deep geological formations. Three types of host rock are considered: rock salt, clay rock and crystalline rock. The Site Selection Act (StandAG1), which came into effect on the 16th of May 2017, defines the successive steps of the repository siting process, which has to ensure the best possible safety conditions for a period of one million years. Based on precaution considerations, the StandAG (§27 (4) StandAG) sets a preliminary temperature limit of 100°C at the outer surface of a repository container for the preliminary safety assessment.

This contribution provides an overview about the state of the scientific and technical knowledge on the limiting temperatures in the repository site selection process of Germany. It also illustrates the different treatments of the definition of temperature limits within other European siting processes. The findings highlight that, in Europe, the proposed criteria which consider temperature at the outer surface of a repository container get more and more into focus of research and discussion especially for the three different types of host rocks.

After presenting the national regulatory frameworks, this contribution summarizes how the European countries address the different temperature related issues for their site selection, their repository concepts and how in turn these all can influence the German safety case strategy for the German site selection. Not at least, links to site selection criteria in other countries (e.g. USA, Japan, Russia) are provided.

Reference

1  StandAG: Standortauswahlgesetz vom 5. Mai 2017 (BGBl. I S. 1074), das zuletzt durch Artikel 2 Absatz 16 des Gesetzes vom 20. Juli 2017 (BGBl. I S. 2808) geändert worden ist.
Testing the ability of submersible spectrophotometers to trace suspended sediment sources at high-temporal frequency
Authors: Lake Niels , Martínez-Carreras Núria , Shaw Peter , Collins Adrian
Published: March 2020

Reliable and detailed information on the primary sources of suspended sediment (SS) and sediment-associated nutrient and contaminant transfers is needed to target mitigation measures for delivering healthy ecosystems and meeting environmental policy objectives. To this end, the SS source fingerprinting approach is proven an effective tool for assembling reliable information on the sources of SS and SS-associated nutrients and contaminants within a catchment. However, SS source estimates at a high temporal resolution are often lacking due to the high workload and costs involved in collecting and analysing SS and soil samples using conventional means. Given this background, here, we propose the use of submersible spectrophotometers that measure absorbance spectra at 2.5 nm intervals in the 200-750 nm range (UV-VIS) in-situ and at high temporal frequency (i.e. minutes) to fingerprint SS sources. We hypothesise that increasing the measurement frequency will eventually help to better characterise changes in sources over time, whilst also giving further insights on how to improve the classical sediment fingerprinting approach, which is currently based on the use of temporally-lumped data. In this research, we first test our approach under fully controlled conditions in a laboratory experiment. To this end, we use a large cylindrical tank (40-L) equipped with a spectrophotometer as well as a LISST sensor (measuring the effective particle size distribution (PSD)). A mechanical stirring device ensures homogeneous conditions in the system and prevents the settling of soil particles (added in solution). The used soil samples originate from different areas within Luxembourg, whereby a selection was made based on differences in tracer properties and colour. The soils were sieved to three different fractions to take account of PSD control on tracer properties. Using the laboratory experiment, we investigated how suspended particle properties affect the absorbance spectra readings. In particular, we looked at the effects of: (i) increasing concentrations of suspended particles, and; (ii) differences in PSD. We then created artificial mixtures composed of two, three and four soil types mixed in different proportions to investigate if the absorbance readings at different wavelengths (i.e., considered as tracers or fingerprints) can be used to un-mix the known proportions of the SS sources. For this, we used the predictions of MixSIAR, a well-established Bayesian tracer un-mixing model. Our preliminary results indicate the promising use of high resolution absorbance data to un-mix artificial sediment mixtures. Ongoing work is testing the approach at larger scales.
Quality assessment of GNSS reference stations: Criteria and Thresholds
Authors: Legrand Juliette , Bruyninx Carine
Published: March 2020

When using a network approach, expressing reliably GNSS position and velocities in a given reference frame (ITRF2014, IGS14, …) requires the identification of ‘stable’ and ‘rebliable’ reference stations. The choice of these reference stations can have a non-negligible impact on the estimated positions and velocities and of course on the derived geodynamic interpretations.

This study will present the work done to address this issue within EUREF and help the users of the EUREF products (more specifically of the EPN multi-year position and velocity solution) to identify the best reference stations in the EUREF Permanent Network (EPN). To that aim, a new station classification was developed based on a set of criteria.

First, the position time series of the stations were analyzed in terms of seasonal signals and scattering.

Then, we quantified the reliability of the velocity estimation: The EPN multi-year position and velocity solution is estimated using CATREF software (Altamimi et al., 2007). We used more realistic velocity error estimates taking into account a temporal correlated noisederived from the Hector software (Bos et al., 2013) and compared the velocity estimates from Hector and CATREF.

Finding a suitable reference station is particularly difficult when dealing with a different period of observations compared to the reference solution. Therefore, finally, we looked for a criterion to assess the stability of the station over its full history. For this, we quantified the velocity variability over time of a station by comparing the velocities estimated using various time spans with velocities from the full time span of the station.

Based on those criteria, the information has been organized and thresholds have been defined in order to end up with a simple station classification, which is currently under evaluation within EUREF. Based on this classification, we also developed a web tool in order to help the user to select the best reference stations in a considered area and for a given period of observation.
Outgoing Long Wave Radiation Dipole of Tropical Cyclones
Authors: Smith Mohan , Toumi Ralf
Published: March 2020

Remote (r ≤ 1800km) outgoing longwave radiation (OLR) fields are investigated in observations, the ECMWF ensemble forecast and reanalysis data. A large scale dipole pattern of low and high fluxes are found in both the observations and model. Low OLR regions are positioned within the cyclone circulation and high OLR regions are found 500-1500km to the north west of the TC. The position of the high OLR region rotates anticlockwise about the TC center as the TC motion vector rotates clockwise from westward to eastward. There is a strong association between the low level wind divergence fields and the high OLR remote region. We propose this remote high OLR region is of interest regarding TC track forecasts. Sub-ensembles selected upon the location of the remote high OLR region improved track forecasts improved by 15\% at 6hrs lead time. This technique out performs those sub-ensembles selected by the inner 750km TC OLR signal, however the best skill improvement in the study selects sub-ensembles by a 3600x3600km TC centered OLR field.
"Terra Antiqua" : a paleogeographic reconstruction plugin for QGIS
Authors: Ruiz Diego , Dupont-Nivet Guillaume , Aminov Jovid , Poblete Fernando , van der Linden Thomas , van Hinsbergen Douwe
Published: March 2020

Paleogeographic reconstructions are essential across disciplines in Earth and Environmental Science from geodynamics to climate, as well as related fields of biology and ecology. They are at the foundation of many academic as well as industrial applications. As for geologic maps, paleogeographic reconstructions integrate a vast amount of multidisciplinary data and interpretations. Building such reconstructions thus requires a large set of sequential procedures to position around the globe various oceanic and continental features and to modify their topographies, bathymetries and shorelines according to the considered dataset included.

We present here a tool that enables to perform simply these operations. It is under development as a plugin for QGIS. With a graphical user interface, preset options can be readily applied to generate quickly multiple reconstructions with varying parameters. This makes project data management and treatment considerably easier, more intuitive and user-friendly. As most tools in GIS do, Terra Antiqua includes help texts incorporated to its interface to guide the user through each module.  The Plugin is divided into modules and this format allows a high degree of flexibility in the order of the reconstruction steps. These are: the compilation of topography and bathymetry, the definition of the paleoshorelines, the topography modification and the interpolation. Resulting paleogeography digital elevation model (DEM) can be visualized and exported in any GIS-supported format – NetCDF, GeoTIFF, Grid (.grd) or as PDF, JPEG, SVG etc. for publication. The tool is tested to make global reconstructions at 50 and 30 Ma.
Characterising extreme rainfall over mountain regions with a network of tipping bucket rain gauges and GPM satellite data
Authors: Buytaert Wouter , Paul Jonathan , Ochoa-Tocachi Boris ,   iMHEA team
Published: March 2020

Mountain regions such as the Andes and the Himalayas are a hotspot of natural hazards. Many of them, in particular floods, landslides, and soil degradation, are related to extreme rainfall events. However, characterising rainfall is complicated by the extreme spatiotemporal gradients, and the scarcity of in situ observations. Characterising extreme rainfall events is particularly problematic because most existing rainfall records are only available at a low temporal resolution (daily or coarser). Here, we analyse records of a network of 77 tipping bucket rain gauges located in Ecuador, Peru, Bolivia and Nepal, with a data availability ranging between 1 and 10 years.

From the raw data we derive rainfall intensities at 5 and 10 minute intervals using composite cubic spline interpolation and smoothing. We then compare those intensities with instantaneous measurements from the Global Precipitation Measurement (GPM) satellite mission. Although correlations are generally low, it is possible to find significant trends that make it possible to interpolate the observed intensities in space, and to generate rainfall intensity quantile maps for the wider high Andean region.
Effect of topographic potential difference and gravity correction on the geoid-quasigeoid separation
Authors: Wang Yan Ming
Published: March 2020

The effect of the topographic potential difference and the gravity correction on the geoid-quasigeoid separation are usually ignored in numerical computations. Those effects are computed in a mountainous Colorado region by using the digital elevation model SRTM v4.1 and terrestrial gravity data. The effects are computed at 1′X1′ grid size in the region. The largest effect is the topographic potential difference. It reaches a maximum of 19.0 cm with a standard deviation of 1.8 cm over the whole region. The gravity correction is smaller, but it still reaches a maximum of 3.0 cm with a standard deviation 0.3 cm for the whole region. The combined (ignored) effect ranges from -12.2 to 20.0 cm, with a standard deviation of 1.8 cm for the region. This numerical computation shows that the ignored terms must be taken into account for cm-geoid computation in mountainous regions.
Knowledge exchange to guide decision support tool development for Chinese agriculture – an example of social science meeting geoscience for sustainable agriculture
Authors: Naylor Larissa , Zheng Ying , Oyesiku-Blakemore Joe , Dennis Sarah , Oliver David , Yang Shunhua , Waldron Susan , Hallet Paul
Published: March 2020

Critical Zone Observatories (CZO) have the potential to offer a holistic, social-ecological systems approach to understanding of agricultural systems. They allow us to consider the inter-linkages of nutrients, water and human interactions across the landscape, to help society better achieve UN sustainable development goals. Here we report on how two different work packages of a multi-partner (UK and China), multi-university project are working together, at the geoscience – social science interface. Social science surveys were used to gain an understanding of knowledge exchange pathways, learning preferences and social dynamics in three regions of China that can usefully inform the design of decision support tools (DSTs). These DSTs are being developed to provide information to users about the consequences of their actions (e.g. effects of fertiliser on water quality) and to identify where changed practice may alleviate degradation of ecosystem services.

 

 

Our work assesses these tools through a Critical Zone (CZ) perspective focusing on farmers, agricultural policy makers (village to county scale) and farm advisors in Chinese agriculture. We explored the best pathways to deliver applicable DSTs in three different Chinese rural areas. We undertook: 1) surveys of Chinese (n = 27) and British (n = 16) scientists researching CZ science in China and 2) surveys and interviews of local stakeholders (592 farmers; 77 officials). This identified how knowledge was exchanged between researchers and users, and what are the preferred and effective ways of knowledge sharing. These data were used to develop a conceptual model of the science-policy-practice interface; identifying different routes for DST knowledge exchange. Alongside this, we carried out a systematic review of over 400 existing DSTs worldwide to identify tools that were: a) suitable for use in China (e.g. lower data requirements); b) had environmental protection goals and c) provided outputs which provide specific support to stakeholders in decisions. Few tools reviewed explained their approaches to KE or engagement with users or assessed the environmental impacts of agricultural practice. Our analysis highlights the need for more interdisciplinary DSTs that are co-produced with users and include both environmental consequences and financial incentives alongside parameters such as crop yield.
Global In-Situ Observations of Essential Climate and Ocean Variables by the Global Drifter Program. Applications and Impacts
Authors: Centurioni Luca , Hormann Verena
Published: March 2020

Accurate estimates and forecasts of physical and biogeochemical processes at the air-sea interface must rely on integrated in-situ and satellite surface observations of essential Ocean/Climate Variables (EOVs /ECVs). Such observations, when sustained over appropriate temporal and spatial scales, are particularly powerful in constraining and improving the skills, impact and value of weather, ocean and climate forecast models. The calibration and validation of satellite ocean products also rely on in-situ observations, thus creating further positive high-impact applications of observing systems designed for global sustained observations of EOV and ECVs.

The Global Drifter Program has operated uninterrupted for several decades and constitutes a particular successful example of a network of multiparametric platforms providing observations of climate, weather and oceanographic relevance (e.g. air-pressure, sea surface temperature, ocean currents). This presentation will review the requirements of sustainability of an observing system such as the GDP (i.e. cost effectiveness, peer-review of the observing methodology and of the technology, free data access and international cooperation), will present some key metrics recently used to quantify the impact of drifter observations, and will discuss two prominent examples of GDP regional observations and the transition to operations of novel platforms, such us wind and directional wave spectra drifters, in sparsely sampled regions of the Arabian Sea and of the North Atlantic Ocean.
Compositional data analysis of sedimentological, mineralogical and geochemical data for the evaluation of Austrian loess and loess loam deposits
Authors: Reitner Heinz , Benold Christian , Filzmoser Peter , Heinrich Maria , Hobiger Gerhard , Mert Can , Rabeder Julia , Reitner Jürgen M. , Wimmer-Frey Ingeborg
Published: March 2020

Austrian loess and loess loam deposits represent an important source of raw materials for the heavy clay industry for centuries. Building material quality of loess and loess loam deposits and their suitability for different applications is significantly influenced by their heterogeneous properties. These depend on the geology of the source area, climatic conditions, geomorphological location, stratigraphic position, intensity of weathering and redeposition potential. The description of occurrences, properties and availability of these raw materials is therefore an important prerequisite to meet the industrial quality requirements. A large number of different sub-datasets exist at the Geological Survey of Austria, which comprise grain-size analysis, bulk rock composition, clay mineralogy, and geochemistry data of loess and loess loam. Within our project, these individual data sets underwent a thorough examination and have been merged into a coherent database to enable the joint regional and statistical analysis of the data. By applying a log-ratio approach the compositional nature of the analysis data has been taken into account for multivariate statistical methods. 
Within our study we focused on the classic Austrian loess regions in the Northern Alpine foreland areas of Upper and Lower Austria and in the Vienna Basin. By transferring the results of the statistical analysis to a Geographic Information System (GIS) these served as the fundamental basis for our categorization of the loess and loess loam occurrences. Taking into account previously published approaches based on soil profile classifications as well as trends and patterns derived from the analysis data, we finally were able to delineate different districts of brick raw materials deposits. These will be made publically accessible to the industry and interested parties as part of the web application of the Austrian Interactive Raw Material Information System IRIS-Online.
Influence of organic carbon cycling on the fate of persistent organic pollutants in marine environments
Authors: Sobek Anna , Nybom Inna , Arp Hans Peter , Berrojalbiz Naiara , Charlton Nathan , Forsell Mari , Gilbert Dorothea , Horlitz Gisela , van Grimbergen Janneke
Published: March 2020

Persistent organic pollutants (POPs) are ubiquitously present in the aquatic environment. They are hydrophobic substances that sorb to organic carbon (OC), and thus their environmental fate is closely linked to OC fluxes and pools. In this project, we test the hypothesis that future changes in the OC cycle can influence POP flux from air to sediment and reduce the POP sink in Baltic Sea sediments. The hypothesis relies on the assumption that the OC sorption capacity is affected by the relative contribution of terrestrial OC as well as the trophic status (oligotrophic versus eutrophic) of the area. Four different coastal sites were sampled, to capture different carbon regimes in terms of nutrient status and level of terrestrial OC influence. Concentrations of POPs were analysed along high-resolution sediment porewater- bottom water interface profiles, in total sediment, suspended matter collected in sediment traps and plankton, in the water column and in air. Stable carbon isotope signatures (δ13C) showed that the sites are different in terms of the influence of terrestrial organic matter, and the sites differ in nutrient conditions.

Preliminary results demonstrate that in general, sediments (three sites analysed) act as a source of PAHs to overlying water, whereas sediment and water more often are in equilibrium for PCBs, although there are variations for individual compounds. At the high nutrient-low terrestrial site, which was sampled at two different seasons, both air and water concentrations were higher for PAHs and PCBs in the autumn compared to the summer, indicating the importance of air as source of these contaminants to the water column. Accordingly, air seems an important source of PAHs to the water column in the low terrestrial-low nutrient site, as concentrations in the water column are increasing towards the water surface, whereas this was not observed for PCBs at the same site. Preliminary results from two contrasting sites in the Gulf of Finland, both with high nutrient levels but with different relative contribution of terrestrial OC, demonstrate higher total sediment concentrations of PAHs in the sediment with more marine OC, which was not observed as clearly for PCBs. Data from the water column indicate that marine OC is more efficient in sorbing POPs as air and water concentrations were similar at both sites, even though the OC vertical export at the high terrestrial site was more than double compared to the low terrestrial site. The full data set, will allow for further evaluation of hypotheses on the links between OC cycling and contaminant fate in the Baltic Sea.
Characterising and quantifying links between water, energy, and food consumption in a water-poor, energy-rich city; Adelaide, Australia
Authors: Shanafield Margaret , Batelaan Okke , Subramani Sundar
Published: March 2020

More than half of the world’s population are urban dwellers, and this percentage is on the rise. Therefore, understanding the links between water, energy, and food requirements of cities plays a critical role in determining global resource consumption. Adelaide is a mid-size, coastal Australian city in Australia with a population of almost 1.3 million inhabitants. With its plentiful access to wind and solar energy, the Adelaide region has one of the highest rates of renewable energy production in the world, and access to additional, conventional energies supplies from other parts of the Australian network. However, the water supplies in this region are theoretically limited, as groundwater depletion is already occurring in the food production areas surrounding the city, and municipal water supplies rely heavily on the fully allocated Murray River system. Therefore, optimization of the food, energy and water requirements of the city provides an opportunity for optimal use of valuable resources. Quantification of these industries was not trivial and provided data availability and comparison challenges.  Lessons learned on a quantitative example of the water-energy-food nexus at city scale are presented.
Assessing mean climate change signals in the global CORDEX-CORE ensemble
Authors: Teichmann Claas , Jacob Daniela , Remedio Armelle Reca , Coppola Erika ,   CORDEX-CORE team
Published: March 2020

The Coordinated Output for Regional Evaluations (CORE) simulation ensemble is an effort of the WCRP CORDEX community to provide high-resolution regional climate change information for the major inhabited areas of the world and thus generate a solid scientific basis for further research related vulnerability, impact, adaptation and climate services. This is especially important in those areas in which only a few high-resolution simulations or only comparatively coarse simulations from global models were available. The driving global climate model (GCM) simulations were selected to cover the spread of high, medium, and low equilibrium climate sensitivity at a global scale. Initially, two regional climate models (RCMs) REMO and RegCM4 were used to downscale GCM output to a spatial resolution of 0.22°. It is intended that the CORDEX-CORE ensemble can then be extended by additional regional simulations to further increase the ensemble size and thus the representation of possible future climate change pathways. 

The aim of this study is to investigate and document the climate change information provided by the current CORDEX-CORE ensemble with respect to the mean climate change in different regions of the world and in comparison to previously existing global climate information, especially those global climate simulations used as boundary forcing for CORDEX-CORE RCMs. First, the regional biases of the RCMs simulations and its driving GCMs simulations were quantified compared to the CRU TS 4.02 observational dataset during the reference period from 1971 to 2000. Second, the near future (2036 to 2065) and far future (2071 to 2099) climate change signals were quantified from the new CORDEX-CORE ensemble. The analysis focuses on the mean temperature and precipitation changes based on the new IPCC physical climate reference regions. For selected regions, the differences of the climate change information at different resolutions are documented. Using this selected regions, the climate change signals from the CORDEX-CORE ensemble were compared to other existing CORDEX simulations and the CMIP5 GCM ensemble. First results of this comparison will be presented.
The internal sedimentary architecture of Terrestrial sinuous ridges: clues to understanding sinuous ridges on Mars
Authors: Sangwan Kartikeya S. , Gupta Sanjeev , Barnes Robert , Banham Steven G.
Published: March 2020

Noachian-Hesperian terrains on Mars host multiple geomorphic and stratigraphic signatures of ancient water flow on early Mars. Sinuous, branching systems of ridges are one such geomorphic landform and have been interpreted as topographically-inverted ancient river channel systems. Characterising the internal sedimentary architecture of such systems is important to constraining the evolution and duration of ancient fluvial flows on early Mars. For example, such ridges are present at the Western delta at Jezero crater, the landing site for the NASA Mars 2020 rover mission. Some studies have used these ridges as time-frozen snapshots of ancient channels and focused on the distribution and geometries of these ridges. However, recent works have characterised these ridges as exhumed channel-belt deposits, composed of multiple channel deposits based on comparisons with similar deposits on Earth. Detailed sedimentary architectural analysis of Terrestrial ridges is needed to provide models for interpreting the earliest fluvial flows on Mars.

Here we present a fine-scale sedimentological analysis of sinuous ridges from the Caspe Formation, Ebro Basin, Spain as potential Terrestrial analogues for sinuous ridge networks on Mars. The Caspe Formation comprises of Oligo-Miocene fluvial deposits of the Guadalope-Matarranya fan system deposited within the endorheic Ebro Basin. The sandstone ridges of the formation are dissected by a number of roads and recent road cuts present a unique opportunity to analyse the fluvial stratigraphy in cross-section. We used traditional field methods and photo-panel interpretations to identify the internal architecture of the ridges and the analysis was complemented with observations from sections parallel to the ridge axes and Unmanned Aerial Vehicles.

Our results provide identification of complete suite of elements preserved within an exhumed channel belt deposits such as channel scour surfaces, channel deposits in the form of lateral and downstream accreting bedforms and barforms, coarser gravel lags and finer-grained deposits from overbank and splay deposits. The ridges preserve a complex continuum of these elements suggesting deposition in an amalgamated channel-fill complex. We also record multi-storey depositional structures with stacked channel elements suggesting an aggrading fluvial system that experienced frequent local avulsion and reoccupation of previous channel positions. The internal architecture of these ridges suggests that Martian sinuous ridges are likely to comprise multiple stacked channel units. If correct this would indicate long lived fluvial activity on early Mars as opposed to short episodes of water flow.
Unsupervised Classification of Convective Organisation in EUREC4A with Deep Learning
Authors: Denby Leif
Published: March 2020

The representation of shallow tradewind cumulus clouds in climate models accounts for majority of inter-model spread in climate projections, highlighting an urgent need to understand these clouds better. In particular their spatial organisation appears to cause a strong impact of their radiative properties and dynamical evolution. The precise mechanisms driving different forms of convective organisation which arise both in nature and in simulations are however currently unknown.

The EUREC4A field campaign presents an unprecedented opportunity to study these clouds by measuring simultaneously the ambient conditions (e.g. windshear, horizontal convergence, subsidence) and the cloud properties. Using an unsupervised neural network able to autonomously discover different patterns of convective organisation this work quantifies the ambient and cloud-properties present in differently organised regimes and in the transitions between these regimes.

The model is trained on GOES-R imagery of the tropical Atlantic. Spatial maps of convective organisation and temporal evolution of these will be presented together with large-scale influences on their development, helping unpick the dynamics of convective clouds in this region.
Influence of Assimilating CYGNSS Ocean Surface Wind Data on Tropical Cyclone Analyses and Predictions
Authors: Annane Bachir , Leidner Mark , Hoffman Ross , Huang Feixiong , Garrisson James
Published: March 2020

For the analysis and forecasting of tropical cyclones, the main benefits of data from the CYGNSS constellation of satellites are the increased revisit frequency compared with polar-orbiting satellites and the ability to provide ocean surface wind observations through convective precipitation. Consequently, CYGNSS delivers an improved capability to observe the structure and evolution of ocean surface winds in and around tropical cyclones. This study quantifies the impact of assimilating CYGNSS delay-Doppler maps, CYGNSS retrieved wind speeds and derived CYGNSS wind vectors on 6-hourly analyses and 5-day forecasts of developing tropical cyclones, using the 2019 version of NOAA's operational Hurricane Weather Research and Forecasting (HWRF) model.
Transfer of displacement between faults of opposed dip
Authors: Childs Conrad , Worthington Robert , Walsh John , Roche Vincent
Published: March 2020

The transfer of displacement between faults that dip in the same direction is well understood and relay ramps between adjacent fault segments have been frequently described. Perhaps counterintuitively, displacement can also be transferred between faults that dip in opposite directions but the structure at the boundaries between opposed dipping faults is not well understood. We constrain the mechanism by which displacement is transferred between opposed-dipping faults by examining the geometries of faulted horizons and fault throw distributions at these ‘conjugate relay zones’.

Structure contour maps of horizons offset by overlapping opposed-dipping faults from different extensional settings display a consistent pattern. Above the line of intersection between the conjugate faults the deformed horizon is flat between converging faults and displacement transfer is reflected in changes in footwall elevation. Below the line of fault intersection the mutual footwall is flat and elevation changes occur in the hanging walls of the divergent faults. These elevation changes can be explained as a simple superposition of the deformation fields of two faults that have retarded lateral propagation due to the presence of the other synchronous fault, irrespective of whether the two faults actually intersect. The observed patterns of horizon elevation strongly resemble those seen at boundaries between adjacent basin-scale half-graben of opposed polarity.
Effects of mesoscale ocean flows on multidecadal climate variability
Authors: Jüling André , von der Heydt Anna , Dijkstra Henk
Published: March 2020

Climate variability on decadal to multidecadal time scales appears to be organized in pronounced patterns with clear expressions in sea surface temperature, such as the Pacific Multidecadal Variability and the Atlantic Multidecadal Variability. These patterns are now well studied both in observations and in global climate models and are important in the attribution of climate change. Results in CMIP5 models have indicated large biases in these patterns with consequences for ocean heat storage variability and eventually the global mean surface temperature.

We use two multi-century Community Earth System Model simulations at coarse (1°) and fine (0.1°) ocean model horizontal grid spacing and study the effect of the representation of mesoscale ocean flows on major patterns of multidecadal variability. We find that resolving mesoscale ocean flows both improves the characteristics of the modes of variability with respect to observations and increases the amplitude of the heat content variability in the individual ocean basins. However, the effect on the global mean surface temperature is relatively minor.
Evolution of oxygen fugacity and copper in the Mesozoic Shanyang porphyry groups, South Qinling
Authors: Luo Biji , Zhang Hongfei , Zhang Liqi , Zhang Chao , Pan Fabin , Yang He
Published: March 2020

Porphyries, closely associated with the copper ore deposits in orogenic belts, are usually considered to have high oxygen fugacity and display high Sr/Y ratios. However, it is still ambiguous whether the high oxygen fugacity and the enrichment of copper are inherited from magma source or obtained by magmatic processes, and the linkage between the high Sr/Y magmas and the formation of porphyry Cu deposits remains unclear. To address these issues, an integrated study of zircon geochronology and oxygen fugacity, petrography, geochemical and Sr-Nd-Hf isotopic compositions for was carried our for the Shanyang porphyry groups from the South Qinling Orogen, Central China. The crystallization ages for the Shanyang porphyries range from ca. 152 to 140 Ma. Our results suggest that the Shanyang porphyry groups are high Ba-Sr granitoids, rather than adakitic rocks, and there is no inevitable connection between high Sr/Y magma and the formation of PCDs. Their parental magmas were derived from partial melting of enriched heterogeneous lithospheric mantle that had been metasomatized by fluid or melt released from the previous subducting slab. Through magma differentiation, the Shanyang porphyry magmas changed from the oxidation state (ΔFMQ +1 to +2) to the reduced state (ΔFMQ +1 to -0.5). The redox condition of magma may be very different from its source and can be shifted remarkably during magmatic evolution that caused by fractional crystallization of garnet in the deep crust and magma degassing in the shallow upper crust. Remelting of the early formed sulfides and gas-brine reactions could enrich copper in the exsolved volatile fluid. Furthermore, the periodic and long-lived magmatic-hydrothermal systems in the shallower magma reservoirs play a critical role in the formation of porphyry Cu deposits.

 
Climate change, historical data and catastrophe modelling
Authors: Dixon Richard , Franklin Sam , Shaffrey Len , Clifford Debbie
Published: March 2020

This presentation will discuss climate change in the context of catastrophe modelling and tail risk. Given that the catastrophe modelling industry typical only has short historical records that provide limited information as to whether hazard is non-stationary, what are the methods and datasets that may aid the catastrophe modelling community to better understand how and whether risk is changing temporally? 

The issues will be framed by using examples of output from a multi-year multi-ensemble 60km global climate simulation, where extra-tropical windstorm daily maximum gust data has been converted into yearly aggregate European insurance loss with the help of PERILS European industry exposure data. The data is used to show how reliance on single historical datasets can produce misleading trends in catastrophe losses - but also potentially point to underlying trends in risk that single historical datasets may not be able to detect.
Internal hydraulics of surface buoyant jets with high aspect ratio
Authors: Yang Adam Jiankang , Lawrence Gregory
Published: March 2020

Surface buoyant jets are commonly found in natural and engineered environments. Typical examples are rivers entering into the ocean, and wastewater discharges into water courses. The surface buoyant jet structure depends on the source properties, geometry and mixing processes. Predicting the mixing and spreading is the key challenge. Recent studies based on layered models have investigated the entrainment rate and spreading rate. However, frictional effects are also important in determining the thickness of the buoyant jet and its lateral spreading.  We will address the effects of entrainment, spreading and friction.

We investigate the surface buoyant jet over a sloping bottom through internal hydraulic theory and field measurements of a river flow into the ocean. In the nearshore zone, the river flow is attached on sea bottom due to the Coanda effect. With a decrease of momentum and thickening, the buoyant jet starts to lift off. At the detachment point, the buoyant jet is critical and the isopycnals are perpendicular to the bottom. We focus on large aspect ratios (river width to the depth) and predict layer thickness, entrainment, lateral spreading and interfacial friction. Comparisons are made with field measurements in Koombana Bay, Western Australia.
Intraseasonal temperature variability features in Northern Eurasia regions under changing climate
Authors: Parfenova Maria , Mokhov Igor I.
Published: March 2020

The estimations of various factors influence on weather regimes formation in Russian regions in transitional (spring, fall) seasons are presented. Changes in those regimes comparing to the middle of 20th century are analyzed, considering atmospheric circulation features under the changes in meridional heat transfer and Rossby waves stationary modes. Using long-term observations of surface air temperature from several locations across Russia, the multimodal features of the probability density functions (PDF) in several decades of 20th and 21st centuries are identified. Focusing on surface temperature anomalies in transitional seasons, we examine the connection between the multimodal features of their PDFs and the nonlinear dependence of surface albedo on temperature during the formation and melting of snow cover. We investigate the impacts of other mechanisms that can facilitate these features, including blocking of zonal atmospheric transport in middle latitudes and formation of blocking anticyclones (blockings) and stationary Rossby waves.
ENVRI knowledge base: A community knowledge base for research, innovation and society
Authors: Liao XiaoFeng , Goldfarb Doron , Magagna Barbara , Stocker Markus , Thijsse Peter , Schaap Dick , Zhao Zhiming
Published: March 2020

The Horizon 2020 ENVRI-FAIR project brings together 14 European environmental research infrastructures (ENVRI) to develop solutions to improve the FAIRness of their data and services, and eventually to connect the ENVRI community with the European Open Science Cloud (EOSC). It is thus essential to share the reusable solutions while RIs are tackling common challenges in improving their FAIRness, and to continually assess the FAIRness of ENVRI (meta)data services as they are developed. 
The FAIRness assessment is, however, far from trivial. On the one hand, the task relies on gathering the required information from RIs, e.g. information about the metadata and data repositories operated by RIs, the kind of metadata standards repositories implement, the use of persistent identifier systems. Such information is gathered using questionnaires whose processing can be time-consuming. On the other hand, to enable efficient querying, processing and analysis, the information needs to be machine-actionable and curated in a knowledge base.
Besides acting as a general resource to learn about RIs, the ENVRI knowledge base (KB) supports RI managers in identifying current gaps in their RI’s implementation of the FAIR Data Principles. For instance, a RI manager can interrogate the KB to discover whether a data repository of the RI uses a persistent identifier service or if the repository is certified according to some scheme. Having identified a gap, the KB can support the RI manager in exploring the solutions implemented by other RIs.
By linking questionnaire information to training resources, the KB also supports the discovery of materials that provide hands-on demonstrations for how state-of-the-art technologies can be used and implemented to address FAIR requirements. For instance, if a RI manager discovers that the metadata of one of the RI’s repositories does not include machine-readable provenance, the ENVRI KB can inform the manager about available training material demonstrating how the PROV Ontology can be used to implement machine-readable provenance in systems. Such demonstrators can be highly actionable as they can be implemented in Jupyter and executed with services such as mybinder. Thus, the KB can seamlessly integrate the state of FAIR implementation in RIs with actionable training material and is therefore a resource that is expected to contribute substantially to improving ENVRI FAIRness.
The ENVRI KB is implemented using the W3C Recommendations developed within the Semantic Web Activity, specifically RDF, OWL, and SPARQL. To effectively expose its content to RI communities, ranging from scientists to managers, and other stakeholders, the ENVRI-FAIR KB will need a customisable user interface for context-aware information discovery, visualisation, and content update. The current prototype can be accessed: kb.oil-e.net. 
Millennial-scale variations in atmospheric N2O during the past 2000 years
Authors: Ryu Yeongjun , Ahn Jinho , Yang Ji-Woong , Brook Ed , Timmermann Axel , Blunier Thomas , Hur Soondo , Kim Seong-Joong
Published: March 2020

Improved knowledge of greenhouse gas-climate feedbacks is required to understand past and future climate changes. Atmospheric nitrous oxide (N2O) is of concern for its potential role in global warming and future stratospheric ozone destruction. Existing ice core N2O records for the Holocene have not been sufficiently consistent to allow an examination of small changes on sub-millennial time scales. Here, we present new high-resolution and high-precision N2O records obtained from the Greenland NEEM (North Greenland Eemian Ice Drilling) and Antarctic Styx Glacier ice cores. Our reconstruction shows, for the first time, a centennial-scale variability of ~10 ppb during the last 2000 years.  Comparisons with proxy records suggest that centennial- to millennial-scale variations in N2O are driven, to a large extent, by changes in tropical and subtropical land hydrology and marine productivity.
Factors governing soil water repellency under tillage management: the role of pore structure and hydrophobic substances
Authors: Li Shengping , Lu Jinjing , Degré Aurore
Published: March 2020

Soil water repellency (SWR) has significant consequences for crop yield, carbon sequestration, aggregate stability, soil erosion, and water movement. It is known to be linked to hydrophobic substances and pore structure. Conservation agriculture could affect SWR through both aspects. However, most of the studies have only focused on hydrophobic substances due to the complexity of soil pore structure measurement and quantification. In this study, X-ray computed tomography at a resolution of 27.27 μm was used to calculate the shape, porosity, and connectivity of the pore network and reveal the impact of hydrophobic substances and pore structure on SWR. All samples were collected from two long-term experimental fields. The treatments were conventional tillage with residue removal (CT), reduced tillage with residue incorporated (RT), and no-tillage with residue mulch (NT) in both of the fields. The water repellency index was determined using the intrinsic sorptivity method by measuring the water and ethanol sorptivity. The results showed that RT and NT treatment increased the porosity of pores of 55-165 μm in diameter that had a positive relationship with ethanol sorptivity and water repellency index, respectively. However, the total porosity and the porosity of >165 μm in diameter had no significant link with SWR properties. RT and NT treatments could enhance ethanol sorptivity by increasing pore connectivity. However, pore connectivity had no effect on water sorptivity because of the hydrophobic substances. NT treatment also reduced water sorptivity by increasing pore surface area and hydrophobic substances. Soil organic carbon and microbial biomass carbon, both of them as hydrophobic substances, were higher under RT and NT treatment than CT. Microbial biomass carbon was more positively correlated to SWR than soil organic carbon, which indicates that microbial biomass carbon is a better indicator explaining tillage effects on SWR. Overall, RT and NT treatment could increase the water repellency index, which was a result of the interactions between pore structure and hydrophobic substances. In order to unravel the mechanisms underlying conservation tillage impacts on SWR more accurately, it is essential to determine both pore structure and hydrophobic substances at the same time.