bluuebunny/crossref_metadata_2025 huggingface dataset:
A new negative feedback mechanism for balancing Tibet uplift-driven CO2 drop: Evidence from Paleogene chemical weathering records in the northern Tibetan Plateau
Authors: Fang Xiaomin , Galy Albert , Yang Yibo , Zhang Weilin , Ye Chengcheng , Song Chunhui
Published: March 2020

The CO2 degassing by plate tectonic process has long been thought to be balanced by weathering of silicate rocks on continents, keeping the Earth a relative stable global carbon cycle and temperature suitable for life creation, survival and evolution. The uplift of the Tibetan Plateau (TP) is hypothesized to enhance erosion and silicate weathering and organic carbon burial, thus cool the global temperature. However, the imbalance resulting from accelerated CO2 consumption by uplift of the TP and a relatively stable CO2 input from volcanic degassing during the Cenozoic should have depleted atmospheric CO2 within a few million years; therefore, a negative feedback mechanism must have stabilised the carbon cycle. Here, we present the first almost complete Paleogene silicate weathering intensity (SWI) records from continental rocks in the northern TP, based on detailed volcanic ash and paleomagnetic dating of two continuous Cenozoic sections in the Xining and Qaidam Basin in NW China. They show that the Paleogene silicate weathering in this tectonically inactive area was modulated by global temperature. These findings suggest that Paleogene global cooling was also strongly influenced by the temperature feedback mechanism that regulated silicate weathering rates and hydrological cycles and maintained a nearly stable carbon cycle. It acted as a negative feedback through decreasing CO2 consumption resulting from the lower SWI and the kinetic limitations in tectonically inactive areas that followed the global cooling. This means that the enhanced erosion and silicate weathering by the uplift of the south and central Tibetan Plateau, thus accelerated CO2 consumption, must be compensated by reducing CO2 consumption of the rest vast continents through their reduced silicate weathering from cooling.
Three years (2017-19) of field observation of the marginal ice the Western Barents Sea
Authors: Marchenko Nataliya
Published: March 2020

Knowledge of sea ice state (distribution, characteristics and movement) is interesting both from a practical point of view and for fundamental science. The western part of the Barents Sea is a region of increasing activity – oil and gas exploration may growth in addition to traditional fishing and transport. So theinformation is requested by industry and safety authorities.

Three last years (2017-19) the Arctic Technology Department of the University Centre in Svalbard (UNIS) performed expeditions on MS Polarsyssel in April in the sea ice-marginal zone of the Western Barents Sea, as a part of teaching and research program. In (Marchenko 2018), sea ice maps were compared with observed conditions. The distinguishing feature of ice in this region is the existence of relatively small ice floes (15-30 m wide) up to 5 m in thickness, containing consolidated ice ridges. In (Marchenko 2019) we described several such floes investigated by drilling, laser scanning and ice mechanical tests, on a testing station in the place with very shallow water (20 m) where ice concentrated. In this article, we summarise three years results with more attention for level ice floes and ice floe composition, continuing to feature ice condition in comparison with sea ice maps and satellite images.

These investigations provided a realistic characterization of sea ice in the region and are a valuable addition to the long-term studies of sea ice in the region performed by various institutions.
On the dependency of simulated volcanically-forced variability to model configuration
Authors: Timmreck Claudia , Toohey Matthew , Zanchettin Davide
Published: March 2020

Several uncertainties affect the simulation of the climatic response to strong volcanic forcing by coupled climate models, which primarily stem from model specificities and intrinsic variability. To better understand the relative contribution of both sources of uncertainties, the Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP) has been initiated as part of the CMIP6 protocol. VolMIP has defined a coordinated set of idealized volcanic perturbation experiments with prescription of the same volcanic forcing and coherent sampling of initial conditions to be performed to the different participating coupled climate models. However, as the VolMIP effort focuses on comparison across different models, an open question remains about how different configurations of the same model affect the comparability of results.

 Here, we present first results of CMIP6 VolMIP simulations performed with the MPIESM1.2 in two resolutions. The low resolution (LR) configuration employs an atmospheric resolution of T63 (~200 km), and nominal ocean resolution of 1.5°. The high resolution (HR) configuration employs twice of the horizontal resolution of its atmospheric component (T127 ~100 km)   with a spontaneously generated QBO, and an eddy-permitting ocean resolution of  0.4°.

In this contribution we illustrate results from the volc-pinatubo experiments, which focus on the assessment of uncertainty in the seasonal-to-interannual climatic response to an idealized 1991 Pinatubo-like eruption, and from the volc-long experiments, which are designed to investigate the long-term dynamical climate response to volcanic eruptions. We compare responses of different climate variables, e.g. near-surface air temperature, precipitation and sea ice on global and regional scale.  Special emphasis will be placed on the volcanic impact on the tropical hydrological cycle.
South Asian Summer Monsoon Variability and its teleconnections in CMIP6 Simulations
Authors: Ravindran Ajayamohan , Veluthedathekuzhiyil Praveen , Cherumadanakadan Thelliyil Sabeerali
Published: March 2020

The mean and subseasonal monsoon variability is evaluated using simulations from 26 CMIP6 models in the present and future scenarios. In particular, the simulation of the monsoon trough, low pressure systems, and its relationship with seasonal rainfall, teleconnections with Pacific and Atlantic Oceans are analyzed, and the corresponding changes in the future scenario are investigated. Based on the fidelity of the model to simulate mean monsoon features, a set of models with good skill is identified. Selected good models are then used to analyze dynamical and teleconnection features. This study highlights and contrasts the performance of CMIP6 models in simulating various monsoon characteristics with CMIP5 models and further stresses the need for better water management strategies.
Study of the distribution of Rare Earth Elements in soil and in Vitis Vinifera L.cv Cannonau in two different regions
Authors: Pepi Salvatore , Medoro Valeria ,   Giulia Piroddi, Elena Marrocchino, Carmela Vaccaro
Published: March 2020

Vitis vinifera L. cultivar “Cannonau” (Magnoliopsida Vitaceae) has been grown for years in the Italian regions to produce a fine wine, with Controlled Designation of Origin (DOC) and Denomination of Controlled and Guaranteed Origin, (DOCG). The International Organization of Vine and Wine (OIV) defined the “terroir” as “a concept which refers to a specific area in which the interactions between the physical and biological environment and applied vitivinicultural practices develops. Whereas, from a geological point of view, the terroir has been defined as the geochemistry of soil, surface and ground water. Recent studies, regarding vitis vinifera, based on geochemical characterization have clearly shown the connection among geological origin, vineyard soil and grape berries. Another way to trace geographical origin can be through the identification of Rare Earth Elements (REEs) in the soil-plant system. However, the study of REEs is also important to define the petrological characterization and the relations between soil and plants.

We evaluated the relationship among the concentrations of rare earth elements (REE) in soil and in “Cannonau” grape berries in vineyards belonging to two different vineyards located in the valleys Pardu and Pelau in Sardinia (Italy) and one in Susegana in the Veneto Region (Northern Italy). The concentration of REE in samples of soil and juice or solid residues of grape berries was determined by inductively coupled plasma mass spectrometry (ICP-MS) and the data were elaborated with multivariate statistics (Linear Discrimination Analysis).The concentration of REEs in soil and grape berry samples allowed an identification of each locality examined . Moreover, the geochemical and statistical analyses allowed to discriminate the vineyard soils and grape berries according to geo-lithological characteristics of each area and to identify possible geochemical markers for the cultivar “Cannonau” .These markers, suitable as terroir fingerprintings, may be useful to avoid fraudulent use of the denomination label and falsification of the Made in Italy trademark.
Dynamical Downscaling of Wind Surface Forcing with Application to the Wave Potential Estimation in the Aegean Sea
Authors: Kozyrakis Georgios V. , Spanoudaki Katerina , Varouchakis Emmanouil A.
Published: March 2020

Over the last decade, a lot of work has been performed to develop wind-wave potential prediction techniques that, effectively and within realistic time-frames, map the local climatology of a specific region. The combination of local and satellite climatic data, has been used, for good reason, in many wind-related-projects as it is linking mesoscale meteorology, with microclimatic weather phenomena. This way the driving geostrophic winds are effectively taken into account for the estimation of low altitude wind distribution.

Using dynamical downscaling methodology, a nesting technique with 1/3 ratio is applied to downscale the raw computational grid of the satellite input data to a finer 3 x 3 Km results grid. This way, higher computational accuracy is achieved over the investigated regions, thus revealing finer wind scales phenomena. For the computational simulations, two different models have been used in order to generate meteo-climate parameters suitable for sea-wave results calculation: a dynamical downscaling model (at regional scale), and a wave model. The first model performs the downscaling of the satellite meteorological data in higher resolution grids for a wide area of the Aegean Sea. The produced fine grid output drives the later wave model in order to estimate the significant wave height and period over the areas of interest. The produced results will later be used in conjunction with novel geostatistical techniques to estimate the wave energy potential distribution in the Aegean and Ionian Sea.

 

 

Acknowledgements

This project has received funding from the Hellenic Foundation for Research and Innovation (HFRI) and the General Secretariat for Research and Technology (GSRT), under grant agreement No [1237].
Changes of Lightning Activity and Vertical Structure in the Inner Core Preceding Tropical Cyclone Rapid Intensification
Authors: Xu Weixin
Published: March 2020

Previous studies suggested that lightning activity could be an indicator of Tropical Cyclone (TC) intensity change but their relationships vary greatly and at times appear contradictory. The importance of total lightning for TC intensification study and forecasting applications has also been pinpointed by several studies. Recently, we revisited this problem using 16 years of TRMM Lightning Imaging Sensor (LIS) measurements and found that reduced (elevated) inner-core total lightning marked rapidly intensifying (weakening) TCs, whereas outer rainband total lightning had opposite trends. It is also shown that the reduced lightning frequency in the inner cores of rapidly intensifying storms was coincident with reduced volumes of 30-dBZ radar reflectivity in the mixed-phase cloud region (-5 to -40 oC), suggesting the lack of large ice particles (e.g., graupel) in the inner cores of rapidly intensifying TCs (which is considered to be important for cloud electrification). To better understand the physical process responsible for these results, we have examined the vertical profiles of radar reflectivity, distribution of precipitation/convection, overshooting radar echo tops (CloudSat), and microwave ice scattering signatures provided by GPM and CloudSat overpasses. This data fusion exercise uniquely provides a more complete understanding of storm electrification, convective intensity, ensemble precipitation microphysics, and storm dynamics in relation to TC intensity change. For example, we have distinguished the convective and microphysical structures between rapidly intensifying (RI) TCs with and without enhanced lightning activity, RI and steady-state TCs, and RI and rapidly weakening TCs.
Nature-based Solutions to Mitigate Environmental Challenges: A Systems Thinking Approach for Integrated Understanding of Human-Nature Interactions
Authors: Seifollahi-Aghmiuni Samaneh , Kalantari Zahra , Santos Ferreira Carla Sofia
Published: March 2020

Urban areas increasingly face challenges associated with dynamic interactions between human and nature systems, such as global (land-, water-use and climate) changes and their related environmental consequences. These challenges can be addressed by sustainable management of coupled human-nature systems that are being stablished and progressed in urban areas. In this context, nature-based solutions (NbSs), as cost-effective actions, are used to protect, sustain, and restore natural or engineered ecosystems for potentially increasing their services delivery to humans. Being inspired and supported by nature systems, NbSs provide human well-being and biodiversity benefits and address coupled environmental-social-economic challenges. This study develops an integrated understanding of human-nature interactions, by investigating wetland functions and their values in Stockholm region, a European densely populated urban area. Wetlands integrate natural and anthropogenic processes and help cities adapt to changes by enhancing their resilience to environmental and social challenges. In this study, a participatory approach has been applied for combining local and scientific knowledge to address the following questions: (i) What are the underlying system dynamics and interactions between urbanization and wetland regulating ecosystem services as coupled human-nature systems? and (ii) How do these dynamics affect synergies and trade-offs in achieving Sustainable Development Goals (SDGs)? Therefore, relevant actors have been involved in thematic sector workshops and followed a systems thinking technique to co-create a causal loop diagram (CLD) as a conceptual system representation. The CLD highlights key components and drivers of the system, providing actor-specific perspectives of interactions and feedback structures within the system. Dynamic hypotheses on the effectiveness and roles of wetlands as NbSs in the study region have also been examined in a fuzzy cognitive map, developed as a semi-quantitative system representation. The results provide insights on wetland contributions to attaining SDGs in urban areas, as well as potential transition pathways toward sustainable development by identifying opportunities and barriers for the study region.
Salt weathering and geoheritage - Sulfate efflorescences in historical underground quarries of tuff
Authors: Germinario Luigi , Oguchi Chiaki T.
Published: March 2020

One of the most popular and intensively extracted building stones in Japan is a Miocene dacite-rhyolite ignimbrite known as Oya-ishi, quarried nearby the city of Utsunomiya (Tochigi). Traces of its historical usage in the last 1,500 years survive in vernacular architecture, construction, rock-cut and relief sculpture, but large-scale exploitation commenced only in the Edo period (i.e., from the 17th century), an epoch of economic growth and flourishing arts and culture. Among the over 200 underground quarries in the region, few are still active, the others abandoned or converted into geoheritage and tourist attractions (e.g., History Museum, Heiwa Kannon monument, Keikan Park). Salt weathering is one of the decay aspects of Oya stone jeopardizing the preservation of those sites of historical and geological interest and, indirectly, visitor safety. The efflorescences on the tuff quarry walls turn out to be composed of sulfates, namely gypsum, mirabilite, and thenardite, their crystallization being controlled by the relevant microenvironmental conditions. In the extremely humid underground spaces, the phases having a very high deliquescence relative humidity are stable: gypsum is essentially ubiquitous, even in the deepest quarry levels, the most environmentally isolated; mirabilite needs a slightly dryer environment, so is observable in the middle levels or semi-underground quarries; thenardite requires further dryer conditions, and is mainly detected in the open air. The mechanisms of formation of these efflorescences are still under investigation: the classic minero-petrographic and geochemical characterization of the rock and its weathering phases is being supported by a microclimatic monitoring in different sites and seasons, and the chemical analysis of rainwater and groundwater. The research direction is aimed at the identification of the environmental and lithological constraints on the salt weathering of Oya tuff, that is: the spatial and temporal variability of relative humidity, and its influence on the cycles of salt crystallization/dissolution and the resulting mechanical stresses; the chemical driving forces, related to the rock mineralogy (zeolites, feldspar alteration, etc.) and water quality.
Strain Partitioning Between the Izmir-Balikesir Transfer Zone and the North Anatolian Fault Zone, NW Turkey
Authors: Tosun Levent , Çakır Elif , Uzel Bora , Sümer Ökmen , Özacar Atilla Arda , Kaymakcı Nuretdin , Langereis Cor
Published: March 2020

The present tectonic framework of the Western Anatolia has been dominated by two major deformations. The first one is the product of the slab-edge processes related to the convergence between Eurasian and African plates along with the Aegean-Cyprean subduction system since the Oligocene, and the second one is the westwards escape of Anatolian Block along the North Anatolian Fault Zone (NAFZ) since the late Miocene. The first one resulted in a widespread extensional deformation in the Western Anatolia and the Aegean region and is associated with slab-detachment and slab-tear processes that gave rise to the development of dynamic topography and various core-complexes (e.g., Cyclades and Menderes). Recent studies have shown that the deferential extensional strain between the core complexes in the region has been accommodated by strike-slip dominated transfer zones, the İzmir-Balıkesir Transfer Zone (İBTZ), which developed (sub)parallel to the extension direction and accommodate differential extension and rotational deformation in the region. The second one gave way to the development of a complex strike-slip deformation pattern and an array of pull-apart basin complexes throughout the northern margin of the Anatolian Block. The NAFZ and İBTZ interact around the Balıkesir-Bursa region resulting in a very peculiar deformation style due to partitioning of strain between these major structures.
This study aims at unraveling how the strain partitioning operates between İBTZ and NAFZ and to reveal the kinematic constraints that produced the present tectonic scheme in the region. The geometry and kinematics of the faults are determined by analyzing 2773 fault slip data obtained from 49 sites evenly distributed throughout the study area. The preliminary results show that the İzmir-Balıkesir Transfer Zone localized after Miocene with the decoupling of strike-slip faults, and to the episodic exhumation of the metamorphic core complexes. The focal mechanism solutions of the recent earthquakes support this decoupling and manifest the seismic activity of the İBTZ. This study is supported by a Tübitak Project, Grant Number of 117R011.
Barotropic instability of a zonal jet on the sphere: From non-divergence through quasi-geostrophy to shallow water
Authors: Shamir Ofer , Paldor Nathan , Garfinkel Chaim
Published: March 2020

Two common approximations to the full Shallow Water Equations (SWEs) are non-divergence and quasi-geostrophy, and the degree to which these approximations lead to biases in numerical solutions are explored using the testbed of barotropic instability. Specifically, we examine the linear stability of strong polar and equatorial jets and compare the growth rates obtained from the SWEs along with those obtained from the Non-Divergent barotropic vorticity (ND) equation and the Quasi-Geostrophic (QG) equation. The main result of this paper is that the depth over which a layer is barotropically unstable is a crucial parameter in controlling the growth rate of small-amplitude perturbations and this dependence is completely lost in the ND equation and is overly weak in the QG system. Only for depths of 30 km or more are the growth rates predicted by the ND and QG systems a good approximation to those of the SWEs, and such a convergence for deep layers can be explained using theoretical considerations. However, for smaller depths, the growth rates predicted by the SWEs become smaller than those of the ND and QG systems and for depths of between 5 and 10 km they can be smaller by more than 50%. For polar jets, and for depths below 2 km the mean height in geostrophic balance with the strong zonal jet becomes negative and hence the barotropic instability problem is ill-defined. While in the SWEs an equatorial jet becomes stable for layer depths smaller than ~3-4 km, in the QG and ND approximation it is unstable for layer depths down to 1 km. These results may have implications for the importance of barotropic instability in Earth's upper stratosphere and perhaps also other planets such as Venus.
Time-dependent behaviour and water influence on the mechanical response of gypsum rock in underground quarry frameworks
Authors: Caselle Chiara , Bonetto Sabrina , Baud Patrick
Published: March 2020

The mechanical response of natural gypsum rock is relevant in a wide range of engineering applications (e.g. tunnel excavation, stability assessment of underground quarries, oil and gas accumulation). In particular, in underground quarry environments, static loading conditions insisting on the gypsum pillars during and after the exploitation activities (i.e. several decades) require a specific attention to the sub-critical time-dependent deformation of the rock. The short-term stability (referred to the possibility of a failure in consequence to the sudden application of the axial load) does not preclude the possibility of deformation or even failure in the long-term.

In addition, the underground drifts of gypsum quarries are often located below the static level of the groundwater table, requiring a continuous water pumping to allow for the accessibility of the drifts themselves. The end of the quarry activity, coinciding with the interruption of the de-watering operations and the re-assessment of the original level of water table, brings to the new water saturation of the gypsum body. The water fills the connected porosity of the rock, influencing the general stability of the underground voids.

For these reasons, the present work aims to investigate the mechanical response of gypsum rock in time-dependent regime, also considering the influence of water saturation. The study proposes an experimental investigation of the influence of water on the rheology of a natural gypsum facies (i.e. branching selenite gypsum), distinguishing between the mechanical effects of a saturating fluid (in relation to the internal pore pressure), that should also be observed with a non-reactive fluid such as oil, and the water-gypsum chemical interactions. This influence of water is investigated in uniaxial compression, under uniaxial creep conditions and conventional triaxial compression. The new mechanical data are accompanied by microstructural observations of the effects induced in the rock by the mechanical compression, aiming to propose a description of the mechanisms involved in the gypsum deformation process.
Impact of FORMOSAT-7/COSMIC-2 RO on High-Resolution Hybrid 3DEnVar System at Central Weather Bureau of Taiwan
Authors: Hong Jing-Shan , Chen Wen-Jou , Chen Ying-Jhen , Jiang Siou-Ying , Fong Chin-Tzu
Published: March 2020

The FORMOSAT-7/COSMIC-2 (simplified as FS-7/C-2 in the following descriptions) is the constellation of satellites for meteorology, ionosphere, climatology, and space weather research. FS-7/C-2 was a joint Taiwan-U.S. satellite mission that makes use of the radio occultation (RO) measurement technique. FORMOSAT-7 is the successor of FORMOSAT-3 which was launched in 2006. the FORMOSAT-3 RO data has been shown to be extremely valuable for numerical weather prediction, such as improving the prediction of tropical cyclogenesis and reducing the typhoon track error. The follow-on FS-7/C-2 mission was launched on 25 June 2019, and is currently going through preliminary testing and evaluation. After it is fully deployed, FS-7/C-2 is expected to provide 6,000 GNSS (Global Navigation Satellite System) RO profiles per day between 40S and 40N.  

In this study, we conduct a preliminary evaluation of FS-7/C-2 GNSS RO data on heavy precipitation events associated with typhoon and southwesterly monsoon flows based on the operational NWP system of the Central Weather Bureau (CWB) in Taiwan. The FS-7/C-2 GNSS RO data are assimilated using a dual-resolution hybrid 3DEnVare system with a 15-3 km nested-grid configuration. In the 15km resolution domain, flow-dependent background error covariances (BECs) derived from the perturbation of ensemble adjustment Kalman filter (EAKF), will be used to conduct hybrid 3DEnVar analysis. In the 3 km resolution domain, the 15 km resolution flow-dependent BECs will be inserted to the 3 km grid using a Dual-Resolution (DR) technique, and then combined with 3 km resolution static BECs, to perform the high-resolution 3DEnVar analysis. The performance of the CWB operational NWP system on quantitative precipitation forecast of significant precipitation events with and without the assimilation of FS-7/C-2 GNSS RO data will be evaluated.
The Mesoscale Convection System of Torrential Rain in Warm Sector over East Side of the Tibet Plateau
Authors: Zhao Qingyun , Zhang Wu
Published: March 2020

The northwest China is located at the northeast of the Tibet Plateau, with a broad zone and complex terrain. The torrential rain occurred occasionally in the region. The formation of torrential rain and defensive ability of human beings are different due to the complex terrain. The storms occurred simultaneously with mountain torrents and debris flows, resulting in major casualties and economic losses. Studies have shown that most of the heavy rain occurred in the front of upper trough under the background of warm and wet southwest flow and near the shear line formed by both northerly and southerly at low level. A heavy rain occurred at the east side of the Tibet Plateau is completely different from previous features of heavy rain in the same region. It happened under the control of warm high ridge and south wind flow field in synoptic scale. Heavy precipitation has emerged in the warm region before large scale rain belt arrived. The torrential rain occurred in warm region mostly appeared in south China and rarely in north area. It has the feature of severe convective precipitation with weak disturbance in synoptic scale. The NWP model is capacity-constrained to forecast it.

A torrential rain in warm sector occurred at east side of Tibet Plateau, with the maximum hourly rainfall of 65mm, along with thunder and lightning. The evolution of mesoscale convective system was analyzed focusing on the development and propagation at by using the data of satellite, CINRAD, automatic weather stations, the conventional observation, and NCEP/NCAR reanalysis data. The results show that, due to the bell-like terrain of the east of Tibet Plateau and the block of Liupanshan mountain, a low-level jet formed as long as 200-300 km on 700 hPa. The low level jet triggered the development of convective cloud band. The forward propagation of Meso-β-scale convective cloud cluster (MCS) was the major cause of Torrential rain. The radar echoes showed obvious characteristics of low center of mass warm cloud precipitation, the zonal distribution in north and south of strong echo monomer greater than 35 dBz, the movement of convective cells with 1time/h along the low-level Jet from south to north. The significant train effect formed zonal torrential rain at east side of Tibet Plateau.

In the environmental conditions of high temperature and humidity, extreme instability of the atmosphere and a potential for severe convective weather, more attention should be paid to the formation and maintain of southwest low-level Jet. It is significant to the formation and development of the convective system in warm sector. In order to improve the forecast ability of NWP model, it is necessary to investigate the mechanics of the formation of torrential rain in the warm sector.

Key words: East side of the Tibet Plateau; Low level Jet; Convective cloud band; Convective cells propagation; Torrential rain in Warm sector
Barite scaling in fractures simulated with nucleation and crystal growth kinetics
Authors: Tranter Morgan , DeLucia Marco , Kühn Michael
Published: March 2020

Deep hydrothermal systems in fractured media are a potential source of geothermal energy. A key problem prevails as a consequence of utilisation that the geochemical system is perturbed and scaling may build up over time. Barite stands out as one of the most ubiquitous scaling agents in deep geothermal systems. It causes irreversible efficiency loss and may be responsible for geothermal power plants to become non-profitable. Due to complex parameter interplay and underlying uncertainties, it is imperative to utilise numerical simulations to investigate temporal and spatial precipitation effects.
In this work, the impact on fracture permeability in the near field of the injection well is assessed. A one-dimensional reactive transport model is set up with heterogeneous nucleation and crystal growth kinetics. In line with potential target hydrothermal systems in the North German Basin, the following parameters are considered in a sensitivity analysis: injection temperature (50 to 70 °C), pore pressure (10 to 50 MPa), fracture aperture (10-4 to 10-2 m), flow velocity (10-3 to 100 m s-1), molar volume (50.3 to 55.6 cm3 mol-1), contact angle for heterogeneous nucleation (0° to 180°), interfacial tension (0.07 to 0.134 J m-2), salinity (0.1 to 1.5 mol kgw-1 NaCl), pH (5 to 7), and supersaturation (1 to 30).
Nucleation and consequently crystal growth can only begin if the threshold supersaturation is exceeded. Therefore, contact angle and interfacial tension are the most sensitive in terms of precipitation kinetics. If nucleation has occurred, crystal growth becomes the dominant process, which is mainly controlled by fracture aperture. Results show that fracture sealing can happen within months (33 days) and the affected range can be in the order of tens of metres (10 m). Predicting the threshold supersaturation is a crucial point in this context, as it essentially determines if barite precipitation becomes relevant.
The uncertainty of parameters influencing nucleation at in-situ conditions is high, emphasising the need to investigate these in more detail. The presented models suggest that barite scaling must be recognised as a serious threat if the supersaturation threshold is exceeded, in which case, larger fracture apertures could help to minimise kinetic rates.
Incorporating the value of nature into assessments of future energy pathways
Authors: Lovett Andrew , Day Brett , Smith Greg , Delafield Gemma , Owen Nathan , Agnolucci Paolo , Bateman Ian , Beaumont Nicola , Carver Steve , Dockerty Trudie , Donnison Caspar , Eigenbrod Felix , Ferguson-Gow Henry , Hastings Astley , Holland Robert , Pearson Richard , Sünnenberg Gilla , Taylor Gail , Ziv Guy
Published: March 2020

The UK government has made formal commitments to reduce GHG emissions (e.g. under the Climate Change Act 2008 and subsequent amendments) and to protect/improve natural capital and the environment (e.g. as part of the 25 Year Environment Plan published in 2018). Meeting these objectives requires an integrated approach to two parallel challenges i) decarbonising the energy system and ii) better understanding and valuation of natural capital and ecosystem services. From an academic perspective this involves bringing together two substantial, but rather weakly connected bodies of research, while also acknowledging that this integration in a UK setting needs to recognise the international context (i.e. a whole systems perspective).

The ADVENT project (ADdressing Valuation of Energy and Nature Together) has been funded by the UK National Environment Research Council to develop conceptual frameworks and modelling tools which ‘integrate the analysis of prospective UK energy pathways with considerations relating to the value of natural capital’. A methodology has been implemented to downscale the outputs of pathways from national energy system models and incorporate environmental impacts into the assessment of different options. This has required defining spatially-optimised distributions of investments in new energy infrastructure using a range of financial and welfare criteria. These distributions are then compared in terms of their construction, transport and land opportunity costs, as well as the implications for biodiversity, greenhouse gas emissions, recreation, visual amenity and water resources.

This paper will present results from comparing different UK energy pathways through to 2050 in terms of the implications of electricity generation from three types of renewables (bioenergy, solar and onshore wind). The results illustrate that i) individual pathways can vary appreciably in their environmental impacts, ii) overall societal welfare can be enhanced by using spatial modelling to incorporate valuations of such impacts into implementation of pathways and iii) assessment outcomes can be sensitive to modelling assumptions (e.g. regarding the proportion of biomass feedstock from domestic or international sources). More broadly, the results demonstrate how important improvements can be achieved in the integration of environmental considerations into the assessment of future energy pathways at regional and national scales. The approach is now being further refined through the UK Energy Research Centre Phase 4 programme and ADVANCES Landscape Decisions project in the UK, as well as the five-country IRENES project funded by Interreg Europe. 
Process-based model evaluation of cold region hydrological processes
Authors: Knoben Wouter , Fayad Abbas , Vionnet Vincent , Clark Martyn
Published: March 2020

Model simulations of hydrological processes are critical for applications in streamflow forecasting and water security assessments. In this work, we develop a model-agnostic benchmarking framework to evaluate the fidelity of continental-domain model simulations. The benchmarking framework includes (1) synthetic test cases to evaluate the implementation of the model equations; (2) process-based diagnostics in research basins to evaluate model representations of individual processes; and (3) continental-domain benchmarks to evaluate the fidelity of large-domain model simulations. As a test case, we use simulations from the Structure for Unifying Multiple Modeling Alternatives (SUMMA) configured across the North America domain. We rely on existing theory about cold-region hydrologic processes and large-domain observations of these processes to define process-specific evaluation metrics. These process diagnostics provide insights in our current ability to model cold region hydrological processes across the North America domain.
Extreme summer precipitation in Central Europe over the past millennium: role of external forcing in enseble of simulations with Earth System models
Authors: Zorita Eduardo
Published: March 2020

Extreme precipitation in Europe over summer time is one type of climate extreme with strongest impact on societies, at present and over the past centuries. In contrast to mean and extreme temperatures, it is still unclear to what extant the external forcing may modulate the intensity and frequency of this type of hydrological extremes. This contribution focuses on the identification of the impact of external forcing on European extreme precipitation over the past millennium in one small ensembles of simulations with the Earth System model MPI-ESM-P and in the Large Millennium Ensemble with the model CESM.

Both models realistically simulate the meteorological conditions that give rise to sustained (over several days) strong precipitation, compared to present conditions. The analysis of both ensembles indicates that the role of the external forcing over the past millennium has been weak at most, with individual members of the ensemble providing different timings for period with high and low probability of extreme summer precipitation in this region. This conclusion is also valid for mean summer precipitation.

This result confirms the evidence obtained from analysis of proxy records, mostly palaeoclimatological records but also historical evidence. This analysis indicates that the frequency and intensity of extreme summer precipitation has been so far independent of the mean climate state.
Altitudinal soil and vegetation transitions in alpine desert, the Central Great Caucasus, Georgia
Authors: Jolokhava Tamar , Kikvidze Zaal
Published: March 2020

Alpine deserts are noteworthy habitats in high mountain systems such as the Caucasus. However, very little is known on the soil properties in these habitats. Another unexplored question is the transition between subnival (lower part of alpine desert) and nival (upper part of alpine desert) belts. We studied soils and vegetation in an alpine desert along its practically entire elevation range (3000-4000 m a.s.l.) on two contrasting slope aspects (north vs south) of Mt. Kazbegi, the Central Great Caucasus, Georgia. Vegetation with standardized stratified-random design and collected soil samples for measuring pH, soil organic content (SOM) and available nutrients (N, P, K) were sampled; the collected data were analyzed with direct gradient methods as well as multivariate ordination. 63 species were recorded and, as expected, strong dependence of species distribution on elevation and between slopes was documented. We found that soil pH increased monotonically with altitude on both N and S slopes and reached alkaline values with bare bedrock. The changes were steeper on the northern slope than on the southern slope, and, remarkably, many relatively abundant species changed their preference to slope aspect from N to S in parallel with the increasing difference in soil pH.  We suspect that the pH  observed shift in slope preference, at least in part, can be explained by the effect of different soil pH. As for SOM, it decreased from very low values to zero at the higher altitudes, whilst available nutrients dropped dramatically and predominantly multispecific vegetation patches characteristic for subnival belt changed abruptly to monospecific patches or solitary plants typical for nival belt. These abrupt changes occurred at 3400-3500m a.s.l., and most probably indicate a vegetation switch between the mentioned belts on Mt. Kazbegi.

Overall, our results show two characteristics of alpine desert vegetation and soils, which have not been documented to date: (1) an unexpected change of slope preference of many relatively abundance plants which probably is associated with different soil pH profiles on N and S slopes, and (2) a vegetation switch between subnival and nival belts that occurs at relatively lower elevations than expected from the concept of alpine-nival ecotone.
Rift propagation north of Iceland: A case of asymmetric plume - rift interaction?
Authors: Larsen Hans Christian , Blischke Anett , Brandsdóttir Bryndís ,   IODP Proposal 976-Pre working group
Published: March 2020

Drilling by the Ocean drilling Program (ODP Legs 104, 152, 163) and geophysical studies have inferred a widespread and strong influence by the Iceland plume on the structure of the ~2500 km long volcanic rifted margins that formed between East Greenland and NW Europe during continental breakupat  ~56-54 Ma. A persistent, but spatially much reduced impact by the plume on crustal structure is evident along the ~250 km Greenland-Iceland-Faeroe ridge (GIFR). Spreading south of the GIFR has remained comparatively stable along the Reykjanes Ridge (RR). By contrast, spreading between the GIFR and northwards to the Jan Mayen Fracture Zone (JMFZ) involved northward rift propagation (~50-25 Ma) away from the Iceland plume and into the East Greenland margin. This was paired with a northward retreat of the initial spreading axis (Aegir ridge (AER)) further to the east. Slivers of the East Greenland continental crust topped by continental plateau basalts extruded during initial breakup were torn off by this northward rift propagation, and form segments of the Jan Mayen microcontinent (JMMC). Rift propagation resulted in the formation of the Iceland Plateau (IP) underlain by anomalously thick and shallow oceanic crust. The striking asymmetry in plate kinematics and crustal structures south and north of Iceland seems associated with a less enriched mantle source feeding the spreading system north of Iceland. This suggests a potentially long-lived north-south asymmetry in the composition and dynamics of the plume that, if confirmed, will favor the existence of distinctly different mantle reservoirs rather than a mixing (entrainment) process followed by a compositional de-convolution process during decompression melting and melt distribution. IODP proposal 976-Pre will address these topics by investigating the temporal and compositional development of the crust of the IP, as well as the transition from rift propagation by the IP rift (IPR) into the present day Kolbeinsey ridge (KR). Drilling will sample 2-3 stages of four IPR propagation stages we have mapped, the transition from the IPR to KR spreading, rifting and timing of transpressive movements along the pseudo-transform zone that linked the propagating IPR to the retreating AER. One drill site hopefully will establish the stratigraphic relationship between the JMMC basalts and the East Greenland plateau basalts. Sediment cover at the drill sites will constrain subsidence history and the paleo-environmental evolution of the high-latitude north-east Atlantic and its connectivity to the global ocean.The proposed drilling addresses long-standing ocean drilling themes of continental breakup, rift propagation, mantle plume reservoirs and structure, and north Atlantic paleoceanography.
Monitoring marine coastal areas
Authors: Mancho Ana M. , Garcia-Sanchez Guillermo , Jimenez-Madrid José Antonio
Published: March 2020

The European Commission has invested in developing services such as the Copernicus Marine Environment Monitoring Services that offer opportunities to new downstream applications. This presentation describes the development of monitoring services in coastal areas at the submesoscale, by addressing synergies between different available marine technologies and products such as satellite images, autonomous surface and underwater vehicles, drone images, downscaled hydrodynamic models, etc, that get inspired in recent success cases [1, 2]. In particular ongoing efforts will be discussed that address the operational implementation of these tools for the management of marine pollution in harbors and coasts with a focus in the hydrodynamic modelling aspects.

Support is acknowledged  from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 821922 (IMPRESSIVE) and from Fundacion Biodiversidad and European Commission (BEWATS).

References

[1] A. G. Ramos, V. J. García-Garrido, A. M. Mancho, S. Wiggins, J. Coca, S. Glenn, O. Schofield, J. Kohut, D. Aragon, J. Kerfoot, T. Haskins, T. Miles, C. Haldeman, N. Strandskov, B. Allsup, C. Jones, J. Shapiro. Lagrangian coherent structure assisted path planning for transoceanic autonomous underwater vehicle missions.  Sci. Rep. 8, 4575 (2018).

[2] V. J. Garcia-Garrido, A. Ramos, A. M. Mancho, J. Coca, S. Wiggins. A dynamical systems perspective for a real-time response to a marine oil spill. Mar. Pollut. Bull. 112, 201-210, (2016).
Burial and origin of permafrost organic carbon in the Arctic nearshore zone
Authors: Fritz Michael , Grotheer Hendrik , Meyer Vera , Riedel Thorsten , Pfalz Gregor , Mathieu Laura , Hefter Jens , Gentz Torben , Lantuit Hugues , Mollenhauer Gesine
Published: March 2020

Increasing air and sea surface temperatures at high latitudes lead to accelerated thaw, destabilization, and erosion of perennially frozen soils (i.e., permafrost), which are often rich in organic carbon. Coastal erosion leads to an increased mobilization of organic carbon into the Arctic Ocean that can be converted into greenhouse gases and may therefore contribute to further warming. Carbon decomposition can be limited if organic matter is efficiently deposited on the seafloor, buried in marine sediments and thus removed from the short-term carbon cycle. Basins, canyons and troughs near the coastline can serve as sediment traps and potentially accommodate large quantities of organic carbon along the Arctic coast. Here we use biomarkers (source-specific molecules), stable carbon isotopes (δ13C) and radiocarbon (Δ14C) to identify the sources of organic carbon in the nearshore zone of the southern Canadian Beaufort Sea. We use an end-member model based on the carbon isotopic composition of bulk organic matter to identify sources of organic carbon. Monte Carlo simulations are applied to quantify the contribution of coastal permafrost erosion to the sedimentary carbon budget. The models suggest that 40% of all carbon released by coastal erosion is efficiently trapped and sequestered in the nearshore zone. We conclude that permafrost coastal erosion releases huge amounts of sediment and organic matter into the nearshore zone. Rapid burial removes large quantities of carbon from the carbon cycle in depositional settings.