bluuebunny/crossref_metadata_2025 huggingface dataset:
The spiralling North Atlantic Subtropical Gyre
Authors: Döös Kristofer , Berglund Sara , Mcdougall Trevor , Groeskamp Sjoerd
Published: March 2020

The North Atlantic Subtropical Gyre is shown to have a downward spiral flow beneath the mixed layer, where the water slowly gets denser, colder and fresher as it spins around the gyre. This path is traced with Lagrangian trajectories as they enter the Gyre in the Gulf Stream from the south until they exit through the North Atlantic Drift. The preliminary results indicate that these warm, saline waters from the south gradually becomes fresher, colder and denser due to mixing with waters originating from the North Atlantic. There are indications that there is also a diapycnal mixing, in the eastern part of the gyre due to mixing with the saline Mediterranean Waters, which would then be crucial for the Atlantic Meridional Overturning. The mixing in the rest of the gyre is dominated by isopycnic mixing, which transforms gradually the water into colder and fresher water as it spins down the gyre into the abyssal ocean before heading north.
A novel approach for the assessment of morphological evolution based on observed water levels in tide-dominated estuaries
Authors: Huayang Cai , Liu Feng
Published: March 2020

Assessing the impacts of both natural (e.g., tidal forcing from the ocean) and human-induced changes (e.g., dredging for navigation, land reclamation) on estuarine morphology is particularly important for the protection and management of the estuarine environment. In this study, a novel analytical approach is proposed for the assessment of estuarine morphological evolution in terms of tidally averaged depth on the basis of the observed water levels along the estuary. The key lies in deriving a relationship between wave celerity and tidal damping or amplification. For given observed water levels at two gauging stations, it is possible to have a first estimation of both wave celerity (distance divided by tidal travelling time) and tidal damping or amplification rate (tidal range difference divided by distance), which can then be used to predict the morphological changes via an inverse analytical model for tidal hydrodynamics. The proposed method is applied to the Lingdingyang Bay of the Pearl River Estuary, located on the southern coast of China, to analyse the historical development of the tidal hydrodynamics and morphological evolution. The analytical results show surprisingly good correspondence with observed water depth and volume in this system. The merit of the proposed method is that it provides a simple approach for understanding the decadal evolution of the estuarine morphology through the use of observed water levels, which are usually available and can be easily measured.
Life and Death in the Jurassic Seas of Dorset, Southern England
Authors: Hart Malcolm , Arratia Gloria , Moore Chris , Ciotti Benjamin
Published: March 2020

There are very few examples of predatory behaviour by coleoids in the fossil record (e.g., Jenny et al., 2019) and, in the known cases, the victims are always fish. The examples described by Jenny et al. (2019) involve Clarkeiteuthis conocauda (Quenstedt, 1849) from the Toarcian (Jurassic) Posidonienschiefer of Southern Germany and the capture of fish assigned to Leptolepis bronni (Agassiz, 1832). In all the described examples, the fish appears to be held in the arms of the coleoids: arms which are identified by the lines of hooks preserved in the position of the arms.

The Jurassic succession of the Wessex Basin, especially that cropping out along the Dorset Coast, contains important Lagerstätten for squid-like coleoid cephalopods. The Blue Lias and Charmouth Mudstone formations have, since the nineteenth century, provided large numbers of important body fossils that inform our knowledge of coleoid palaeontology. In many of these mudstones specimens of palaeobiological significance have been found, especially those with the arms and hooks with which the living animals caught their prey. This is particularly true in the case of a specimen in the collections of the British Geological Survey (GSM 87477), identified, as Clarkeiteuthis sp. cf. C. montefiorei (Buckman, 1879), which was found in the nineteenth century from an un-specified location near Lyme Regis. This specimen is seen to have a fish, identified as Dorsetichthyes bechei (Agassiz, 1837), being held by two arms that are positioned on each side of the fish which is aligned with the jaws of the ‘squid’.  The bones in the head of the fish are broken in a manner that suggests a quite violent attack, and not simple crushing during burial and taphonomy. While the fish is damaged in ways that are suggestive of it already being dead, has the ‘squid’ choked to death, or was its death the result of sinking to the sea floor and being overcome by, for example, reduced oxygen conditions in the water column? Whatever the cause of death this unique specimen and is the oldest that shows a direct feeding attack by a ‘squid’ on a fish that was ca. 200 mm in length.

Jenny, D., Fuchs, D., Arkhipkin, A.I., Hauff, R. B., Fritschi, B. and Klug, C. 2019. Predatory behaviour and taphonomy of a Jurassic belemnoid coleoid (Diplobelida, Cepahlopoda). Scientific Reports, 9: 7944, 11pp. [doi.org/10.1038/s41598-019-44260-w].
Centrifuge-model test study of key hazard factors of deep toppling deformation and disaster pattern of anti-dip layered-rock slope under gravity
Authors: Zheng Da , Zhao Hua
Published: March 2020

To study the toppling deformed body before construction of the dam at the Gushui hydropower station, we developed here a physical model of the slope on the basis of known local geology and of similarity theory. We simulated valley trenching by a method using prior produced block modules and three levels of excavation, and we studied key hazard factors of deep toppling deformation and the disaster pattern related to anti-dip, layered-rock slope under gravity by a five-stage centrifuge-model test and Universal Distinct Element Code numerical-simulation analysis. The results show the following: (1) The occurrence, development and destruction of deep toppling deformation of anti-dip layered rock slopes must have gone through a long geological history; the accumulation of energy and deformation is a very long process, and accelerated-deformation is closely related to changes in external conditions (such as excavation, earthquake, etc.); (2) lithologic conditions (relatively weak rock mass), structural conditions (appropriate layer thickness and dip angle), and external conditions (valley trenching or excavation of slopes) are key factors for deep toppling deformation, while the free-surface condition is the key hazard factor; (3) deep toppling deformation can lead to multilevel bending zones at different depths inside the slope after the several stages of valley trenching (multilevel excavation); the bending zone is gradually connected from the foot of the slope all the way to the top, which eventually becomes the failure boundary; and the development and connection of the bending zone may result in the overall shear failure of the slope along the bending zone; (4) for deep toppling deformation, we propose a qualitative-judgment index and quantitative-judgment indicators of the degree of toppling deformation. We derived quantitative-judgment formulas for the degree of toppling deformation and the calculation formulas were used for the maximum depth of toppling deformation, and we established a system for discrimination of destruction patterns for deep toppling deformation of anti-dip slope.
How isostasy explains continental rifting in East Africa?
Authors: Bagherbandi Mohammad , Gido Nureldin A. A.
Published: March 2020

The principle of isostasy plays an important role to understand the relation between different geodynamic processes. Although, it is difficult to find an exact method that delivers a complete image of the Earth structure. However, gravimetric methods are alternative to provide images of the interior of the Earth. The Earth’s crust parameters, i.e. crustal depth and crust-mantle density contrast, can reveal adequate information about the solid Earth system such as volcanic activity, earthquake and continental rifting. Hence, in this study, a combine Moho model using seismic and gravity data is determined to investigate the relationship between the isostatic state of the lithosphere and seismic activities in East Africa. Our results show that isostatic equilibrium and compensation states are closely correlated to the seismicity patterns in the study area. For example, several studies suggest that African superplume causes the rift valley, and consequently differences in crustal and mantle densities occur. This paper presents a method to determine the crustal thickness and crust-mantle density contrast and consequently one can observe low-density contrast (about 200 kg/m3 ) and thin crust (about 30 km) near the triple junction plate tectonics in East Africa (Afar Triangle), which confirms the state of overcompensation in the rift valley areas. Furthermore, the density structure of the lithosphere shows a large correlation with the earthquake activity, sub-crustal stress and volcanic distribution across East Africa.
Is the relation between the solar wind dynamic pressure and the magnetopause standoff distance so simple?
Authors: Samsonov Andrey , Branduardi-Raymont Graziella
Published: March 2020

The relation between the solar wind dynamic pressure and magnetopause standoff distance is usually supposed to be RSUB~Pd-1/N. The simple pressure balance condition gives N=6, however N varies in empirical magnetopause models from 4.8 to 7.7. Using several MHD models, we simulate the magnetospheric response to increases in the dynamic pressure by varying separately the solar wind density or the velocity. We obtain different values of N depending on which parameter, density or velocity, has been varied and for which IMF orientation. The changes in the standoff distance are smaller (higher N) for a density increase and greater (smaller N) for a velocity increase for southward IMF. We explain this result by enhancement of the Region 1 current that moves the magnetopause closer to the Earth for a high solar wind velocity. We suggest for developers of new empirical magnetopause models in the future to replace the simple relation between RSUB and Pd with a fixed N by a more complicated relation which would separate inputs in the dynamic pressure from the density and velocity taking into account the IMF orientation.
Do diverse mixtures of cover crop residues alter the soil microbial community and increase soil function?
Authors: Shu Xin , Zou Yiran , Shaw Liz , Todman Lindsay , Tibbett Mark , Sizmur Tom
Published: March 2020

Cover crops are a contemporary tool to sustainably manage agricultural soils by boosting fertility, suppressing weeds and disease, and benefiting cash crop yields, thus securing future food supply. Due to the different chemical composition of crop residues from different plant families, we hypothesised that a mixture of cover crop residues may have a greater potential to improve soil health than the sum of the parts. Our experiment focused on the impact of four cover crops (clover, sunflower, radish and buckwheat) and their quaternary mixture on soil respiration and the soil microbial community in an 84-day microcosm experiment. On average adding cover crop residues significantly (P < 0.001) increased soil respiration from 29 to 343 µg C g-1 h-1 and microbial biomass from 18 to 60 µg C g-1, compared to the unamended control during 84 days’ incubation. Cover crop addition resulted in a significant (P < 0.001) alteration of the soil microbial community structure compared to that of the control. The quaternary mixture of cover crop residues significantly (P = 0.011) increased soil respiration rate by 23.79 µg C g-1 h-1 during the period 30 to 84 days after residue incorporation, compared to the average of the four individual residues. However, no significant difference in the size of the microbial biomass was found between the mixture and the average of the four individuals, indicating the mixture may invest resources which transit dormant microbial species into a metabolically active state and thus boost microbial respiration. Analysis of similarity of microbial community composition (ANOSIM) demonstrated the mixture significantly (P = 0.001) shifted microbial community structure away from buckwheat (R = 0.847), clover (R = 0.688), radish (R = 0.285) and sunflower (R = 0.785), respectively. This implies cover crop residues provide a niche specialization and differentiation on a selection of microbial communities that favour certain plant compounds. While applying cover crop residues has positive impacts on soil function, we found that applying a mixture of cover crop residues may provide greater potential to select for microorganisms or activate dormant microbial species which result in higher soil function. The outcome of this study will help seed suppliers to design, and farmers to select, novel cover crop mixtures which enhance soil function synergistically, leading to a greater potential to sustainably improve soil health.
Transport of Phytophthora cactorum Zoospores in Unsaturated Sand Columns
Authors: Flury Markus , Yu Yingxue
Published: March 2020

Phytophthora cactorum, is an economically important plant pathogen causing sever damage on a wide range of crops, fruits, and ornamental plants. P. cactorum's infective potential and its spatial dissemination relies on rapid and copious production of asexual zoospores. However, little is known about P. cactorum zoospore transport behavior in porous media, impeding the development of effective technology in controlling  infection and disease spreading. In this study, we investigated the transport and retention of P. cactorum zoospores in sand columns at three levels of water saturation (100%, 65%, 48%). Both motile and encysted zoospores were studied as well as carboxylate-modified polystyrene microspheres with the same size as the zoospores (10 um). We hypothesized that (1) motile zoospores are more readily transported than polystyrene microspheres under the same conditions, implying the minor role of size (straining) and the critical role of zoospore motility in controlling zoospore transport; (2) the higher mobility of motile zoospores compared to that of encysted zoospores is caused by the lack of sticky chemicals and the existence of flagella on the surface of motile zoospores; and (3) transport of motile and encysted zoospores, as well as of polystyrene microspheres is enhanced as column saturation increases.
Climate Services for Improving Society's Resilience in China
Authors: Wang Yujie , Song Lianchun
Published: March 2020

ABSTRACT

  With global warming and fast urbanization in China, more and more climate services are urgently needed to manage climate-related disasters better, adapt to a changing climate, and ensure sustainable economic development for improving climate-related society’s resilience. This paper describes the current primary needs for climate services and introduces a series of examples of climate services successfully provided to agriculture, water, energy, urban planning, major engineering projects and ecological economy in China.

These examples of climate services indicate that climate services play a very important role for improving climate-related resilience and sustainable development of society. During the development and implementation of these climate services, both benefits of climate services and some challenges for climate services have been found. The paper highlights the experiences and challenges of these climate services as following:

Firstly, climate services should be tailored to each user individually and be usable. Therefore, providers of climate services should enhance service capability and service consciousness. Secondly, building of interdisciplinary expert team is very important. It can bridge and narrow the gaps in whole climate service chain. Thirdly, climate service quality, observation network, spatial and temporal resolution of climate model and climate prediction accuracy need to be greatly improved. Finally, the feedback of climate service from users is also very important for high efficiency of climate services.
The multiple interactions of banana production, biodiversity, trade and climate in the Philippines
Authors: Ortiz Andrea Monica
Published: March 2020

Banana is a globally important fruit, and the Philippines is one of the world’s largest producers of banana both for domestic consumption and for export. While the popular fruit provides an important source of nutrition and economic revenue, banana production has many negative impacts on the environment. This is due to the input-intensive nature of banana production, as well as the habitat loss and expansion associated with growing trade demands for Philippine bananas, primarily from China, Japan and South Korea. The increased homogeneity of the landscape for banana cultivation also has impacts on threatened Philippine species.

 

An additional factor of climate risk is added to the multiple interactions between banana production and the environment: the Philippines is vulnerable to climate change and climate hazards. Approximately 20 tropical cyclones enter the Philippine Area of Responsibility every year and are a significant cause of losses and damages to agriculture, particularly banana production which is sensitive to strong winds. Thus, there is a complex set of interactions between banana production, its negative impacts on the environment, the increasing exposure of plantations to climate hazards, and the role of banana in the local diet and economy.

 

Data on agriculture, trade and tropical cyclones are used to show that a number of threatened Philippine species occur within agricultural pressure zones from banana production, some of which overlap with protected areas. An analysis of agricultural and economic data shows that damages from tropical cyclones are increasing, but tropical cyclones themselves are not increasing in intensity nor frequency. This means that agricultural expansion has impacts both on biodiversity and on the sustainability of banana production itself. Several recommendations to adapt growing systems to be both resilient and more supportive of biodiversity are offered.
BSc Applied Physics: A physics degree for students with non-standard qualifications
Authors: Wood Alan , Neal Bill , Sawyer Nicolas , Rawlings James
Published: March 2020

In the UK, the primary route to a physics degree is through studying for advanced level qualifications (known as A-levels) in both physics and mathematics. 38,958 students were entered for A-level examinations in physics in 2019, with the majority of these candidates also entered for A-level mathematics.

In recent years the UK has seen a growth of vocational, technical and wide entry qualifications. The vocational and technical qualifications are targeted at teenagers, and the latter targeting mature students returning to education later in life. These qualifications all cover a wider breadth of material, but in less depth than traditional A-levels. In order to ensure that these students can succeed at a physics degree, Nottingham Trent University developed a new course, BSc Applied Physics.

BSc Applied Physics is designed to follow on directly from vocational, technical and wide entry courses, including the BTEC Extended Diploma in Applied Science and Diplomas in Access to Higher Education. In the first year of BSc Applied Physics students have extra workshops to support their studies, and extra sessions on mathematics for physics. The aim is that, at the end of the first year, these students should have the same mathematical ability as year 1 students on our main BSc Physics course. The BSc Applied Physics students then have a choice. They can either continue with BSc Applied Physics, which focusses on the applications of physics, or transfer to a more traditional BSc Physics programme.

The purpose of this poster is to showcase to teachers how this type of non-standard degree programme can benefit students studying for non-traditional qualifications.
Exploring the effects of biodiversity and elemental stoichiometry on terrestrial carbon balance
Authors: Fernández-Martínez Marcos , Sardans Jordi , Peñuelas Josep , Janssens Ivan
Published: March 2020

Global change is affecting the capacity of terrestrial ecosystems to sequester carbon. While the effect of climate on ecosystem carbon balance has largely been explored, the role of other potentially important factors that may shift with global change, such as biodiversity and the concentration of nutrients remains elusive. More diverse ecosystems have been shown to be more productive and stable over time and differences in foliar concentrations of N and P are related to large differences in how primary producers function. Here, we used 89 eddy-covariance sites included in the FLUXNET 2015 database, from which we compiled information on climate, species abundance and elemental composition of the main species. With these data, we assessed the relative importance of climate, endogenous factors, biodiversity and community-weighted concentrations of foliar N and P on terrestrial carbon balance. Climate and endogenous factors, such as stand age, are the main determinants of terrestrial C balance and their interannual variability in all types of ecosystems. Elemental stoichiometry, though, played a significant role affecting photosynthesis, an effect that propagates through ecosystem respiration and carbon sequestration. Biodiversity, instead, had a very limited effect on terrestrial carbon balance. We found increased respiration rates and more stable gross primary production with increasing diversity. Our results are the first attempt to investigate the role of biodiversity and the elemental composition of terrestrial ecosystems in ecosystem carbon balance.
Reexamining the Relationship of La NiÃ±a and the East Asian Winter Monsoon
Authors: Wu Zhiwei
Published: March 2020

The northern and the southern modes are two distinct principle modes that dominate the winter mean surface air temperature (Ts) variations over East Asia (EA). The cold southern mode is represented by a significant cooling south of 45°N and is linked to La Niña events. An objective criterion, which could distinguish the spatial distributions and the maximum center of sea surface temperature anomaly (SSTA), is used to classify the La Niña events into two categories: mega-La Niña and equatorial La Niña. Their impacts are inspected onto the Ts southern mode. The mega-La Niña, featured by a significant K-shape warming in the western Pacific with the maximum SSTA cooling centered in the tropical central Pacific. As a response, an anomalous barotropic high is generated over North Pacific (NP) implying a weak zonal gradient between ocean and the EA continent, which induces a neutral Ts southern mode. The equatorial La Niña characterizes a significant cooling in the tropical eastern Pacific with convective descending motions shifting eastward to the east of the dateline. The resultant low-level circulation anomalies show an anomalous subtropical NP low and a gigantic abnormal EA continent high. The strong zonal gradient results in significant northerly anomalies over EA from 55°N to southeastern China. Over the mid-upper troposphere, the anomalous subtropical NP low extends westward to the Korean Peninsula, leading to a strengthened and southward shifted EA trough. Such abnormal circulation patterns favor the intrusion of cold air to southern EA and correspond to a strong Ts southern mode. The numerical results well validate the above processes and physical mechanisms. 
Shape and distribution anisotropy of irregular arrangements of diverse bodies – a 3D computational model
Authors: Biedermann Andrea Regina
Published: March 2020

The magnetic fabric of strongly magnetic materials originates from (1) self-demagnetization in bodies of non-isometric geometry, and (2) magnetostatic interactions between bodies with non-random distribution. These contributions, termed shape anisotropy and distribution anisotropy, carry information about a rock’s formation or deformation history. Both may be important when magnetite grains control the anisotropy of a rock, or when the pore space of a rock is impregnated with strongly magnetic fluid. The relative importance of each contribution to the overall anisotropy is debated, partly because it is influenced by many factors, including the body shape, orientation, or spacing. Another challenge is that existing models of distribution anisotropy consider infinite regular arrangements of equal bodies and take into account nearest neighbour interactions only. These simplifications make it difficult to predict distribution anisotropy in real rocks, where particles or pores are distributed irregularly, and display a range of sizes, shapes and orientations. A new model is presented here, which calculates both shape and distribution anisotropy for irregular assemblages of diverse bodies – differing in their size, shape, and orientation. The model assumes ellipsoidal bodies of equal intrinsic magnetic susceptibility in a non-magnetic matrix. Input parameters include the coordinates of each body centre, dimensions and orientation vectors of the three principal axes. These can be derived from imaging and X-ray computed tomography, or be pre-defined parameters of man-made samples. Calculations were verified against magnetic pore fabric measurements performed on synthetic samples with known pore parameters. The model is expected to advance our understanding of the interplay between shape and distribution anisotropies in natural samples. Hence, it will facilitate structural interpretations in samples whose magnetic fabrics are predominantly controlled by magnetite, as well as the interpretation of magnetic pore fabrics in future studies.
Developing Prototype Climate Services in CSSP China
Authors: Weeks Jennifer , New Stacey , Dunbar Tyrone , Golding Nicola , Hewitt Chris
Published: March 2020

There is an increasing demand for tailored climate information to feed into decision making. At the UK Met Office, we are responding to this need through work in the Climate Science for Services Partnership (CSSP) China, a scientific research programme in collaboration with the China Meteorological Administration and the Institute of Atmospheric Physics at the Chinese Academy of Sciences. We are applying a full cycle of prototyping to a range of new and existing climate services for priority sectors in China, such as food security and urban hotspot satellite mapping, using leading climate research to co-develop useful and useable climate services.

Recent research in food security has produced a toolkit for risk to crop production across multiple regions in China. We are now evolving the accessibility and communication of this information with decision-makers to enable delivery of this service to the appropriate end-user groups. We are also working to tailor urban hotspot satellite data to specific users, for instance the health sector, to identify and inform vulnerable populations. Through appropriate user engagement, such as workshops, surveys and interviews, we are exploring specific stakeholder requirements to pull-through science to services. This work has wider implications in having the potential to feed into important adaptation decisions and to demonstrate the effectiveness of the cycle of prototyping.
Suspended particulate matter in a submarine canyon: What are we looking at?
Authors: Haalboom Sabine , de Stigter Henko , Duineveld Gerard , Reichart Gert-Jan , Mienis Furu
Published: March 2020

Throughout the world’s oceans, water layers with increased suspended particulate matter concentrations, so called nepheloid layers, play an important role in the lateral transport of sediment, organic matter and pollutants. Nepheloid layers are persistent features in submarine canyons, where they are formed under influence of energetic hydrodynamics. To evaluate their importance it is crucial to properly quantify the amount and type of material that is transported. However, interpretation of turbidity data is not straightforward, since the detected signal is not only dependent on the concentration of particles, but also on the physical characteristics. Therefore we investigated how turbidity fluctuations induced by internal tides in the Whittard Canyon (northern Bay of Biscay, NE Atlantic Ocean) are reflected in time series data, recorded by different types of commonly used optical and acoustic sensors. Results show that in the surface water the transmitted light signal is strongly affected by the chlorophyll-bearing phytoplankton, whilst only a modest response is found in backscattered light. If left unaccounted for, this would result in an overestimation of the suspended particulate matter concentration in this layer. At the bottom of the canyon optical and acoustic sensors responded differently during one tidal cycle, interpreted as cyclic resuspension, whereby different phases of disaggregation, reaggregation and settling of particulate matter were observed. The differences in the records have important implications on the estimation of mass fluxes of suspended particulate matter, which are vital for understanding for instance carbon transport processes in the bottom boundary layer.
Drought impacts in Alpine regions – classifying and investigating the most affected sectors in heterogeneous mountain terrain
Authors: Stephan Ruth , Erfurt Mathilde , Blauhut Veit , Stahl Kerstin
Published: March 2020

Drought is rarely associated with Alpine regions, but as documented in recent years droughts have caused a variety of impacts even in these humid mountain climates. Accordingly, a reduction of vulnerability to drought in Alpine and pre-Alpine regions is required in order to minimize future impacts from upstream to downstream areas and across political boundaries. Therefore, sound information of Alpine droughts as well as knowledge of their impacts is essential. But drought-specific data on the multiple economic losses in mountain regions are scarce and may differ from the usually assessed agriculturally-dominated lowlands. This study aims to clarify todays state of the art on drought impact information in Alpine regions and claims data needs for a comprehensive understanding of Alpine drought risk. More specifically, the objective is to systematically assess the differences of impacts specific to the Alpine region compared to non-Alpine regions. The hypothesis is that specific climate conditions due to the heterogeneous terrain and high altitudes determine the Alpine environment as well as the economical practices and societal adaptations, which differ strongly from lowlands. Subsequently, the sectoral-impacts in mountain regions might vary substantially, especially with regard to the onset and severity of impacts as well as their spatial and temporal extend. The European Drought Impact Report Inventory (EDII) compiles knowledge on the impacts of drought events across Europe from a variety of information sources based on more than 10,000 reported impacts. The current content of the EDIIs database was filtered to the Alpine Space region which make up about 15 % of all entries in all 15 main categories of the classification system. The main affected sectors are ‘agriculture and livestock farming’,’ ‘public water supply’ and ‘energy and industry’. The high proportion of impacts in the latter category is a main difference in the distribution of impacts compared to that of entire Europe. For the individual Alpine countries and regarding the detailed subtypes of the impacts, however, substantial variability was found among the different countries. To obtain a comprehensive risk assessment further research has to establish novel ways to collect more regional impact information for these strongly heterogeneous research areas, with respect to climate, topography and report languages.
A 300-year high resolution Greenland ice record of large-scale atmospheric pollution by arsenic in the Northern Hemisphere
Authors: Lee Khanghyun , Han Changhee , Jun Seong-Joon , Lee Jong Ik , Hong Sungmin
Published: March 2020

We report the first high-resolution record of arsenic (As) observed in Greenland snow and ice for the periods 1711 to 1970 and 2003 to 2009 AD. The results show well-defined large-scale atmospheric pollution by this toxic element in the Northern Hemisphere, beginning as early as the 18th century. The most striking feature is an abrupt, unprecedented enrichment factor (EF) peak in the late 1890s, with a ~30-fold increase in the mean value above the Holocene natural level. Highly enriched As was evident until the late 1910s; a sharp decline was observed after the First World War, reaching a minimum in the early 1930s during the Great Depression. A subsequent increase lasted until the mid-1950s, before decreasing again. Comparisons between the observed variations and Cu smelting data indicate that Cu smelting in Europe and North America was the likely source of early anthropogenic As in Greenland. Despite a significant reduction of ~80% in concentration and ~60% in EF from the 1950s to the 2000s, more than 80% of present-day As in Greenland is of anthropogenic origin, probably due to increasing As emissions from coal combustion in China. This highlights the demand for the implementation of national and international environmental regulations to further reduce As emissions.
Estimation of the offshore extreme winds at 100m over JiangSu province based on spectral correction and numerical simulation
Authors: Chang Rui , Zhu Rong , Yin Yizhou , Ma Wentong , Zhang Daquan
Published: March 2020

Offshore wind energy development and utilization plays an important role in haze governance and fulfilling the reduction commitments in advance. The reserve estimation of offshore wind resource in China is abundant enough to meet the basic needs from the exploitation of wind power. Recently, more and more attention is paid to the accurate estimation of the offshore extreme winds, which impose an important effect on the wind turbine designs and operations. Different from the abundant study of the typhoon extreme winds, because of lack of the effective methods, it shows a significant deficiency in the study of offshore extreme winds over the mid-high latitude, which is also the key area for the exploitation of wind power. Therefore, based on numerical modeling and spectrum analysis, the paper developed a practical, reliable and robust method for 50-years extreme wind estimation that can be applied for other mid-latitude offshore area in China. Taking into account the complex climatic characteristics of China's mid-latitude offshore area affected by high latitude cold winter wind and tropical cyclone, the 50-yr return wind speeds at 100m over Jiangsu offshore area were estimated by this new method. It was shown that (1) affected by the strong cold winter winds, the 50-yr return wind speed in the northern part of Jiangsu offshore area exceeded 40 m/s; (2) the 50-yr return wind speeds of 40 m/s, or even 44m/s near Xiangshui and Rudong was related to the limited typhoon activities; and (3) the 50-yr return wind speeds over the central Jiangsu offshore area were generally lower than 35 m/s. This study may not only provide a scientific basis of the design and operation of offshore engineering, such as offshore wind farms in the future, but also contribute to future understanding of the extreme climate events in China and the development of atmospheric boundary layer theory as well (This abstract has been published in Acta Meteorologica Sinica, 2019, 77(5): 938-948. doi:10.11671/qxxb2019.054).
An Analysis and Example of Use of the GPM Gridded Text Products
Authors: Stocker Erich Franz , Kelley Owen , West Jason
Published: March 2020

This poster provides the design, content and purpose of the
Global Precipitation Measurement (GPM) gridded text
products. Gridded text products at the same time and space resolution are
available from the start of the TRMM period in January 1998 through the
current GPM data collection period. The poster provides an example of the
use of this data product by examining the structure of the Indian monsoon as
well as examining the monsoon during El Nino and La Nina periods. It will
also look at diurnal precipitation during the Indian monsoon season. As
part of the examination of the Indian monsoon using the gridded text
product, the poster demonstrates the ease of integration with other data.
In this case, Sea Surface Temperature (SST) data that is relevant to the Indian monsoon is examined
side-by-side with the precipitation data. It further demonstrates the ease
of aggregating the daily gridded data across many years while still
retaining the hourly structure that enables diurnal studies. The GPM
gridded text product is currently the only level 3 GPM product which can
be aggregated in this way. The representation of data in ASCII format
allows potential users to concentrate on the scientific analysis rather
than the physical format of the data. In summary, the poster provides an
overview that uses examples to demonstrate the efficacy of this unique GPM
data product.
Efficient Analytical Upscaling of Conductivity Tensor for Three-dimensional Heterogeneous Anisotropic Formations
Authors: Liao Qinzhuo , Lei Gang , Patil Shirish
Published: March 2020

We propose an efficient analytical upscaling method to compute the equivalent conductivity tensor for elliptic equations in three-dimensional space. Our approach uses perturbation expansion and Fourier analysis, and considers heterogeneity, anisotropy and geometry of coarse gridblocks. Through low-order approximation, the derived analytical solution accurately approximates the central-difference numerical solution with periodic boundary conditions. Numerical tests are performed to demonstrate the capability and efficiency of this analytical approach in upscaling fluid flow in heterogeneous formations. We test the method in synthetic examples and benchmark cases with both Gaussian random fields and channelized non-Gaussian fields. In addition, we examine the impact of each parameter on the upscaled conductivity, and investigate the sensitivity of the variance and correlation lengths to the coefficients. We also indicate how to extend this approach to multiphase flow problems.
Biomagnification of methylmercury in a marine plankton ecosystem
Authors: Wu Peipei , Zakem Emily , Dutkiewicz Stephanie , Zhang Yanxu
Published: March 2020

Methylmercury is greatly bioconcentrated and biomagnified in marine plankton ecosystems, and these communities form the basis of marine food webs. Therefore, evaluating the potential exposure of methylmercury to higher trophic levels, including humans, requires a better understanding of its distribution in the ocean and the factors that control its biomagnification. In this study, a coupled physical/ecological model was used to simulate the trophic transfer of monomethylmercury (MMHg) in a marine plankton ecosystem. The model includes phytoplankton, a microbial community, herbivorous zooplankton (HZ), and carnivorous zooplankton (CZ). The model captured both shorter food chains in oligotrophic regions, with small HZ feeding on small phytoplankton, and longer chains in higher nutrient conditions, with larger HZ feeding on larger phytoplankton and larger CZ feeding on larger HZ. In the model, trophic dilution occurred in the food webs that involved small zooplankton, as the grazing fluxes of small zooplankton were insufficient to accumulate more MMHg in themselves than in their prey. The model suggested that biomagnification was more prominent in large zooplankton and that the microbial community played an important role in the trophic transfer of MMHg. Sensitivity analyses showed that with increasing body size, the sensitivity of the trophic magnification ratio to grazing, mortality rates, and food assimilation efficiency (AEC) increased, while the sensitivity to excretion rates decreased. More predation or a longer zooplankton lifespan may lead to more prominent biomagnification, especially for large species. Because lower AEC resulted in more predation, modeled ratios of MMHg concentrations between large CZ and HZ doubled when the AEC decreased from 40% to 10%. This suggested that the biomagnification of large zooplankton was particularly sensitive to food assimilation efficiency.
Mercury concentrations in diverse lean fish species of the western Mediterranean
Authors: grimalt Joan , Capodiferro Marco , Junque Eva , Marco Esther
Published: March 2020

The Mediterranean Sea is a water body in which the concentration of mercury is much higher than in the other world seas and oceans. Most inputs of this metal originate from the general atmospheric fallout. However, in this semi-enclosed environment there are specific sources that should be identified to understand the causes of the high toxicity by this metal. A significant proportion of Mediterranean fish devoted to human consumption is above the mercury threshold set by the European Community as suitable for human consumption. The proportion is even much larger if the recommended World Health Organization threshold is considered.

 

Oily fish is known for containing mercury concentrations above these thresholds. Lean fish has been investigated in much fewer cases. The present study is devoted to this second fish type that constitutes a substantial component of human diet. Thus, the study of mercury and methylmercury in fish from local fishermen marketed in diverse Mediterranean sites has provided information on the exposure of diverse populations to this metal and has afforded a description of the Mediterranean areas that have received highest mercury spills.

1350 commercial seafood samples from the Western Mediterranean Sea were collected (Feb 2014-July 2019) in several sites such as Mallorca, Menorca, Eivissa, Alacant (Spain), Marseille (France), Genoa, Alguer, Civitavecchia (Italy). Samples from Egypt and the Atlantic Ocean (Senegal, Mauritania coasts) were also taken for comparison. Fish species were selected considering the most consumed by the population.

Comparison of the mercury concentrations in the specimens of the same fish species collected at different sites revealed where are the hot spots of introduction of the excess of this metal in comparison to the atmospheric fallout and allowed the identification of the source processes.

The fish species were grouped in three trophic levels, those feeding on plankton (first), on small fish and crustaceans (second) and on fish and cephalopods (third).

A considerable number of the analyzed fish species exceeded the maximum levels proposed by the European legislation, such as dusky grouper (100% of the examined specimens), common dentex (65%), conger (45%), common sole (38%), hake (26%) and angler (15%), among others. Representation of the Hg concentrations vs. weight of each specimen from the third trophic level showed a significant positive correlation, r = 0.78 (p < 0.01).

The average THg intake due to fish consumption, 0.61 µg/g ww, involved Hg estimated weekly intakes of 5.7 µg/kg bw for children aged 7-12 years and 4.4 µg/kg bw for adults. These values were higher than the provisional tolerable weekly intakes for total Hg intake recommended by FAO/WHO, 4 µg/kg bw, 140% and 110%, respectively.
On Determination of the Intensity and Size Frequency Distribution of Convective Vortices: Applications to Martian Dust Devils
Authors: Kurgansky Michael
Published: March 2020

Dust devils play a major role on Mars, providing a significant proportion of the total dust removal from the surface and its injection into the atmosphere, thus largely determining the overall radiative regime and the climatic state of the Martian atmosphere. The amount of dust lifted to the atmosphere by a population of dust devils is determined by the number density of dust devils (their number per unit area) and by their size-frequency and intensity-frequency distributions. Using the Abel transform, a two-step methodology has been developed to determine the marginal statistical distributions of convective vortices, including dust devils, on their intensity (pressure drop in the vortex center) and size (diameter), based on statistics of transient pressure drops recorded when the vortices pass near a pressure sensor placed on the surface of the planet. In a first step, if the pressure profile within the vortex is realistically modeled then the intensity-frequency distribution in the population of vortices can be inferred from the statistics of peak pressure drops recorded alone. If the observed statistics can be approximated with a truncated power-law distribution and in the absence of an apparent correlation between the vortex diameter and the maximum pressure drop at its center, then the measurements provide an unbiased power-law estimate of the actual intensity-frequency distribution. In a second step and in a practically important case when the distribution of vortices on their intensity follows the power law, the problem of determining the vortex size-frequency distribution is solved from data obtained in pressure time-series surveys. This two-step technique has been applied with success to Mars Science Laboratory (MSL) convective vortices.

This work was supported by the Presidium of the Russian Academy of Sciences, project no. 19-270. The method of inferring the vortex size-frequency distribution was developed with the support from the Russian Science Foundation (grant no. 18-77-10076).

References:

Kurgansky M.V. On the statistical distribution of pressure drops in convective vortices: Applications to Martian dust devils // Icarus. Volume 317, 1 January 2019, Pages 209-214. https://doi.org/10.1016/j.icarus.2018.08.004.

Kurgansky M.V. On determination of the size-frequency distribution of convective vortices in pressure time-series surveys on Mars // Icarus. Volume 335, 1 January 2020, 113389. https://doi.org/10.1016/j.icarus.2019.113389.
Predicting below-surface pore velocity profiles in porous media from above-surface wind speed and porous medium gas permeability
Authors: Poulsen Tjalfe G.
Published: March 2020

Below-surface horizontal pore air velocity profiles in porous media in response to above-surface wind conditions were measured for 16 combinations of wind speed (1.4 – 5.7 ms-1) and main wind gust frequency (0 – 1 Hz) in four granular porous media (particle size: 0.6 – 10 mm) yielding 64 combinations of wind condition and porous medium. Measurements were carried out under controlled (wind tunnel) conditions using a recently developed experimental gas tracer tracking method. Gusty wind conditions were induced by a wind driven propeller capable of variable rotation frequencies.

A recent empirical model for predicting wind-induced horizontal pore velocity in porous media (using one empirical parameter, B together with surface wind speed as input) was validated against the experimental data and found to provide accurate approximations. Further investigations revealed that B could be accurately predicted from porous medium gas permeability. Overall the results indicate, that it is possible to accurately predict below-surface wind-induced pore velocity profiles based on the above-surface wind speed profile and the porous medium gas permeability.

 