bluuebunny/crossref_metadata_2025 huggingface dataset:
Particle number size distribution measurements of PM1 and PM10 in fogs and implications on fog droplet evolutions
Authors: Tao Jiangchuan , Ma Nan , Zhang Yanyan , Kuang Ye , Hong Juan , Su Hang , Cheng Yafang
Published: March 2020

CCN number concentration (NCCN), particle size-resolved activation ratio at supersaturation (SS) of 0.10% and particle number size distribution (PNSD) in dry state of both ambient PM1 and PM10 particles were measured in the North China Plain in November in 2018. Two fog events were observed during nighttime of 12nd and 13rd Nov. During fog events, the dry particle concentrations sampled from the PM10 inlet were much higher than those from PM1 inlet for particles (particle size bins) with diameter larger than ~200 nm. Additional sub-micron particles sampled by PM10 inlet but not been sampled by PM1 inlet indicates that these particles have grown into droplets with diameter larger than 1um. The growth of particle size by over 5 times can be resulted from not only the activation to form fog droplets but also the hygroscopic growth at RH higher than 99%. There was no significant decrease of particle number concentration larger than ~200 nm during fog periods compared with those beyond the fog periods, suggesting that the fog droplets may be generally smaller than 10um and can be sampled by PM10 inlet. The size-resolved activation ratio curve showed that the critical diameter was about 160-180nm and there was significant difference (>50%) of NCCN at SS of 0.1% between PM1 and PM10, mainly due to the difference of PNSD between PM1 and PM10 in fogs. The measured PNSD and CCN-activity might be applied on the analysis of the relationship between fog droplets and the corresponding ambient supersaturations.
Lightning optical context associated with ASIM TGFs
Authors: Mezentsev Andrey , Østgaard Nikolai , Marisaldi Martino , Kochkin Pavlo , Neubert Torsten , Chanrion Olivier , Heumesser Matthias , Reglero Victor , Christiansen Freddy , Genov Georgi , Ullaland Kjetil
Published: March 2020

Launched and installed at the International Space Station in April 2018, the Atmosphere-Space Interactions Monitor (ASIM) provides science data since June 2018. Suite of onboard instruments contains optical and high energy detectors payloads. Modular Multi-spectral Imaging Array (MMIA) includes three photometers (180-240 nm, 337 nm and 777.4 nm) sampling at 100 kHz, and two cameras (337 nm and 777.4 nm) sampling at 12 Hz. It allows for lightning and transient luminous events (TLEs) observations during the orbital eclipses. The Modular X- and Gamma-ray Sensor (MXGS) detects X- and Gamma-ray photons, and is dedicated to detection of Terrestrial Gamma-ray Flashes (TGFs). The mutual relative timing accuracy between MXGS and MMIA is as good as +/- 5 µs.

 

TGFs are known to be associated with the +IC lightning discharges. ASIM provides a unique possibility for simultaneous observations of TGFs together with the underlying optical activity inside the thundercloud. In this contribution we summarize the almost two years of ASIM observations to make an overview of the various optical contexts accompanying the TGF production.
Balneology in Estonia: importance of the geochemical backgound information of the Estonian curative mud
Authors: Kapanen Galina , Terasmaa Jaanus
Published: March 2020

In Estonia, natural remedies were commonly used during the first half of the 19th century. Thanks to its specific geological and geomorphological characteristics, Estonia has several significant deposits of lacustrine and marine curative (or therapeutic) mud, which has public health and commercial benefits. Many Estonian spas have traditionally incorporated a combination of natural remedies with a range of physical therapies, including gentle exercise, massage and heat and water therapies. Yet, the mud research in Estonia has been stagnating since the 1990s, and therefore one of the main limiting factor for the redevelopment of the public and commercial use is a lack of up-to-date scientific understanding about the sediment composition and deposit characteristics.

There is a long-term tradition in using fine-grained sediments (mud) for cosmetic and medical purposes but more precise information about the characteristics of such sediments is lacking. Since there are no specific standards regarding the bio-geo-chemical composition of curative mud, only the different geochemical and bioactive compound groups could be identified.

We reviewed the regional history of curative mud and the existing scientific rationale for the public and commercial applications of mud for healing purposes. We mapped spatial distribution organic and mineral matter, heavy metals in the surface sediments Estonian deposits of curative mud. Polycyclic aromatic hydrocarbons (PAHs) were controlled for the Haapsalu curative mud. Importantly, the geochemical characterisation is used to provide insights into all of the mud deposits and the broader ecosystem services of muds. The presence of heavy metals in mud is not always dangerous because many factors can affect their toxicity, including pH, and the oxygen, mineral and organic content. Muds can be used in assessing environmental quality, since the pollutants contained in them reflect the conditions of the water-body they were deposited in. The mechanisms of action of the curative mud are not fully elucidated; the net benefit is probably the result of a combination of mechanical, thermal and chemical effects. Additional studies are necessary to clarify the mechanisms of action of balneology.
A hybrid CNN-LSTM based model for the prediction of sea surface temperature using time-series satellite data.
Authors: Jonnakuti Pavan Kumar , Tata Venkata Sai Udaya Bhaskar
Published: March 2020

Sea surface temperature (SST) is a key variable of the global ocean, which affects air-sea interaction processes. Forecasts based on statistics and machine learning techniques did not succeed in considering the spatial and temporal relationships of the time series data. Therefore, to achieve precision in SST prediction we propose a deep learning-based model, by which we can produce a more realistic and accurate account of SST ‘behavior’ as it focuses both on space and time. Our hybrid CNN-LSTM model uses multiple processing layers to learn hierarchical representations by implementing 3D and 2D convolution neural networks as a method to better understand the spatial features and additionally we use LSTM to examine the temporal sequence of relations in SST time-series satellite data. Widespread studies, based on the historical satellite datasets spanning from 1980 - present time, in Indian Ocean region shows that our proposed deep learning-based CNN-LSTM model is extremely capable for short and mid-term daily SST prediction accurately exclusive based on the error estimates (obtained from LSTM) of the forecasted data sets.

Keywords: Deep Learning, Sea Surface Temperature, CNN, LSTM, Prediction.

 
Sediment provenance of the East Siberian Arctic shelf: evidence from clay minerals and chemical elements
Authors: Li Qiuling , Qiao Shuqing , Shi Xuefa , Hu Limin , Bai Yazhi , Zhu Aimei , Cui Jingjing
Published: March 2020

    Grain size, clay minerals and major and trace elements of surface sediment samples collected from the East Siberian Arctic shelf are analyzed. Based on factor analysis and cluster analysis the study area is classified into four provinces, the main sediment sources of each provinces is discussed. The results show: province I covers the coastal estuary of the Kolyma River and the Indigirka River. The sediments are mainly composed of silt and sandy silt, and characterized by highest content of SiO2, TiO2, Zr, Sr and low content of other elements. Illite is dominant which accounting for 70% of the whole clay minerals. This area is strongly influenced by terrestrial sources from the Kolyma River and the Indigirka River. ProvinceⅡis located in the middle of the East Siberian Sea, where the sediments are generally silt and mud. The content of Al2O3, K2O, MnO and Ni are relatively high. Clay minerals composition is similar to Province I, but MnO/TiO2 ratio is higher. The sediments in this area are mainly fine-grained imported by rivers, which are also influenced by sea ice process. As the distance increasing offshore, the content of marine authigenic components begin to increase. Province Ⅲ is located in the northern East Siberian Sea, sediments there are mainly mud. Elements such as Al2O3, K2O, V, Li reach the maximum value in this area. The content of illite is the lowest, semctite and kaolinite reach the maximum (>10%). Fine sediments in this area are probably influenced by Atlantic waters and the Beaufort Gyre. Province Ⅳ is located in Chukchi Sea where the sediments consist of silt and sandy silt. Elements are characterized by higher contents of CaO, P2O5, and the content of Chlorite reach peak (>20%). Sediments in this area are significantly influenced by the Pacific inflow water.

    Note: This study was supported by the Marine S&T Fund of Shandong Province for Qingdao National Laboratory for Marine Science and Technology (Grant No. 2018SDKJ0104-3) , National Natural Science Foundation of China (Grant No. U1606401，41722603) and National Program on Global Change and Air-Sea Interaction (GASI-GEOGE-03)
General Spectrum Fitting for Energetic Particles
Authors: Liu Zixuan , Wang Linghua , Fu Haobo , Sam Krucker , Robert Wimmer-Schweingruber
Published: March 2020

We propose a general fitting formula of energy spectrum of suprathermal particles, J=AE-β1[1+(E/E0)α](β1-β2)/α, where J is the particle flux (or intensity), E is the particle energy, A is the amplitude coefficient, E0 represents the spectral break energy, α (>0) describes the sharpness of energy spectral break around E0, and the power-law index β1 (β2) gives the spectral shape before (after) the break.  When α tends to infinity (zero), this spectral formula becomes a classical double-power-law (logarithmic-parabola) spectrum. When both β2 and E0 tend to infinity, this formula can be simplified to an Ellison-Ramaty-like equation. Under some other specific parameter conditions, this formula can be transformed to a Kappa or Maxwellian function. Considering  the uncertainties both in particle intensity and energy, we fit this general formula well to the representative energy spectra of various suprathermal particle phenomena including solar energetic particles (electrons, protons,  3He and heavier ions), shocked particles, anomalous cosmic rays, hard X-rays, solar wind suprathermal particles, etc. Therefore, this general spectrum fitting formula would help us to comparatively examine the energy spectrum of different suprathermal particle phenomena and understand their origin, acceleration and transportation.
224Ra/228Th disequilibrium in sediments of Lake Taihu: Implications of nitrogen fluxes across the sediment–water interface
Authors: shi Xiaoyan , luo Xin , jiao Jimmy.Jiu , huang Jing , lu Meiqing , liang Wenzhao
Published: March 2020

Radium-224 /Thorium-228 (224Ra/228Th) disequilibrium in sediments is an advanced proxy of benthic processes and has been gradually used to quantify the fluxes and solute transfer across the sediment–water interface (SWI). This study makes the first attempt to explore the nitrogen fluxes across the SWI of Lake Taihu, the third largest and highly eutrophic freshwater lake in eastern China, based on the plumbing of 224Ra/228Th disequilibrium in the lake sediments. The microscopic sediment cores (0-20 cm) were collected in different parts of the lake, and exchangeable 224Ra and 228Th in bulk sediments were measured. Dissolved inorganic nitrogen (DIN) in pore water and overlying lake water were also analyzed. Deficits of 224Ra compared to its parent isotopes 228Th were observed in the lake sediments, suggesting the influences of mixing processes. The deficits were relatively significant in the western and northern parts, which are consistent with the relative high-eutrophicated areas of the lake. One-dimensional (1D) radium-thorium diagenetic model in the sediment was used to estimate the benthic fluxes based on the 224Ra deficits. Results show that the benthic fluxes of 224Ra varied from -0.428 to 1.170 dpm cm-2 d-1, and the bio-irrigation and molecular diffusion are considered to be the major factors. Specifically, in the severely eutrophicated area of the lake, the bio-irrigation predominates in benthic fluxes, reaching up to 97.1% of the deficit of 224Ra. The DIN benthic fluxes were also quantified, leading to a flux estimation of 3.41 mol m-2 d-1, which exceeds riverine input (2.63 mol m-2 d-1) and the loading derived from lacustrine groundwater discharge (0.02~0.03 mol m-2 d-1). This study reveals that sediment processes could be the vital factors for the lake nutrient loadings, and highly contribute to the lake eutrophication. This study is constructive for the water remediation and ecosystem restoration in Lake Taihu and other large eutrophic lakes elsewhere.
Assimilation of atmospheric infrasound data to constrain tropospheric and stratospheric winds
Authors: Amezcua Javier , Nasholm Peter , Blixt Marten , Charlton-Perez Andrew
Published: March 2020

We use acoustical infrasound from explosions to probe an atmospheric wind component from the ground up to stratospheric altitudes. Planned explosions of old ammunition in Finland generate transient infrasound waves that travel through the atmosphere. These waves are partially reflected back towards the ground from stratospheric levels, and are detected at a receiver station located in northern Norway at 178 km almost due North from the explosion site. The difference between the true horizontal direction towards the source and the back-azimuth direction of the incoming infrasound wave-fronts, in combination with the pulse propagation time, are exploited to provide an estimate of the average cross-wind component in the penetrated atmosphere. 
We perform offline assimilation experiments with an ensemble Kalman filter and these observations, using the ERA5 ensemble reanalysis atmospheric product as background (prior) for the wind at different vertical levels. Information from both sources is combined to obtain analysis (posterior) estimates of cross-winds at different vertical levels of the atmospheric slice between the explosion site and the recording station. The assimilation makes greatest impact at the 12-60 km levels, with some changes with respect to the prior of the order of 0.1-1.0 m/s, which is a magnitude larger than the typical standard deviation of the ERA5 background. The reduction of background variance in the higher levels often reached 2-5%. 
This is the first study demonstrating  techniques to implement assimilation of infrasound data into atmospheric models. It paves the way for further exploration in the use of infrasound  observations (especially natural and continuous sources) to probe the middle atmospheric dynamics and to assimilate these data into atmospheric model products.  
Possible albedo reduction due to light absorbing impurities in snowpack observed at various sites
Authors: Aoki Teruo , Niwano Masashi , Matoba Sumito , Tanikawa Tomonori , Kodama Yuji , Hirozawa Yoichiro
Published: March 2020

Possible albedo reduction due to light absorbing impurities (LAI) in snowpack observed at various sites in the world are investigated. Reviewing previously measured black carbon (BC) concentrations, their values distribute in a range of 0.07-0.25 ppbw (ng of BC in g of snow) in Antarctica, 0.55-20 ppbw in Greenland Ice Sheet (GrIS), 4.4-87.6 ppbw for the other Arctic except GrIS, and 4-1221 ppbw for mid-latitudes. As albedo reduction rate by LAI depends on snow grain size, it is more enhanced by larger grain snow such as melt form (melting snow) than smaller grain snow such as precipitation particles (new snow). By assuming two typical snow grain radii rs = 1000 and 50 µm, respectively for those snow grain shapes, the albedo reduction as a function of BC concentration can be calculated with physically based snow albedo model. The result indicates that albedo in Antarctic snow is not affected by BC in any case of snow grain radius. In GrIS albedo reduction due to BC is small around 0.006 for rs = 50 µm (new snow) but it rises to 0.026 for rs = 1000 µm (melting snow), suggesting a few percent of albedo reduction could occur under warmer climate condition due to enhanced snow metamorphism. In the other Arctic except GrIS, the maximum albedo reductions for rs = 50 µm (1000 µm) are 0.015 (0.064) at the maximum BC concentration (87.6 ppbw). For. mid-latitudes, it is 0.070 (0.24) for rs = 50 µm (1000 µm) at the maximum BC concentration (1221 ppbw). These results mean albedo reduction in highly polluted area of mid-latitudes cannot be ignored even in case of new snow and is more serious for melting snow.

We have conducted energy budget and snow pit observations at Sapporo (43°N, 141°E, 15 m a.s.l), Japan since 2005. In addition, elemental carbon (EC~BC) and mineral dust concentrations in snowpack were also monitored for snow samples collected twice a week from 2007 by the thermal optical reflectance (TOT) method and gravimetric measurement of a filter. During 10 years from 2007 to 2017, the medians of EC and dust concentrations are 196 ppbw and 2700 ppbw, respectively. Using those data, contribution of LAI to albedo reduction and the radiative forcing (RF) were estimated. The 10-year-mean albedo reduction and RF due to BC+dust are 0.053 and +6.7 Wm-2, respectively, in which BC effect on albedo reduction is 5.6 times larger than dust. The albedo reduction by BC+dust for only melting period is 0.151, that is 4.8 times larger than that for accumulation period. The effect of LAI on albedo reduction is enhanced by snow grain growth as well as an increase of LAI in melting period compared to that for accumulation season.
Sand Wave Migration and its Factors on Giant Sand Ridge in Taiwan Strait
Authors: Liao Yin-Hsuan , Hsu Ho-Han , Wu Jyun-Nai , Chen Tzu-Ting , Yang Eason Yi-Cheng , Mirza Arif , Liu Char-Shine
Published: March 2020

        Submarine sand waves are known to be induced by tidal currents and their migration has become an important issue since it may affect seafloor installations. In Taiwan Strait, widely spreading sand waves have been recognized on the Changyun Ridge, a tide-dominated giant sand ridge offshore western Taiwan. However, due to lacking of high-resolution and repeated geophysical surveys before, detailed characteristics and migrating features of the sand waves in Taiwan Strait were poorly understood. As new multibeam bathymetric and seismic data were collected repeatedly during 2016 - 2018 for offshore wind farm projects, we can now advance the understanding of sand wave characteristics and migration patterns in the study area. We apply a geostatistical analysis method on bathymetry data to reveal distribution and spatial characteristics of the sand waves, and estimate its migration pattern by using an updated spatial cross-correlation method. Then, sedimentary features, internal structures and thicknesses of sand waves are observed and estimated on high-resolution seismic profiles. Our results show that the study area is mostly superimposed by multi-scaled sandy rhythmic bed forms. However, the geomorphological and migrating characteristics of the sand waves are complicated. Their wavelengths range from 80 to 200 m, heights range from 1.5 to 8 m, and crests are generally oriented in the WNW-ESE direction. Obvious sand wave migration was detected from repeated high-resolution multi-beam data between 2016 and 2018, and migration distances can be up to ~150 m in 15 months. The average elevation change of the seafloor over the whole survey area is ~3.0 m, with a maximum value of 6.9 m. Moreover, the sand waves can migrate over 30 m with ~2.5 m elevation change in 2 months and migrate over 5 m with ~1 m elevation change in 15 days. The results also show that the orientation of wave movement can be reversed even within a small distance. By identifying the base of sand wave on seismic profiles, the thicknesses of sand waves are found ranging from 1 to 10 meters. The base of wave structure become slightly deeper from nearshore to offshore. Our results indicate that the thickness of sand waves increases with degree of asymmetry and migration rate. By bathymetric and reflection seismic data analyses, systematic spatial information of sand waves in the study area are established, and we suggest that not only tidal currents can affect sand wave migration patterns, but also wave structures and thicknesses play important roles in sand wave migrating processes and related geomorphological changes.
Causality in the diversity-abundance relationship across the main World’s forest biomes: insights for nature-based mitigation solutions
Authors: Madrigal-Gonzalez Jaime ,   World's natural forests
Published: March 2020

Increasing evidence now exists for a tight connection between tree diversity and carbon storage capacity. As part of the Paris Agreement (COP21), forests play a critical and prominent role to reach the ambitious goal of net-zero emissions in the second half of this century. Besides reducing emissions from deforestation and forest degradation (also known as REDD), maintaining and enriching tree assemblages could thus help mitigating climate change via increased abundance and more efficient resource use.

However, recent evidence questions this widespread idea of positive diversity effects on forest carbon storage. Specifically, tree diversity may not always be a causal mechanism but rather a consequence of tree abundance and productivity (following the ‘more individuals hypothesis’). To test these contrasting hypotheses, this contribution analyses the most plausible causal pathways and their stability along global climatic gradients in the diversity-abundance relationship across the World’s main forest biomes, using a dataset comprising more than 2,500 forest plots and 83,800 trees sampled in pristine forest landscapes in all continents (except Antarctica).

We demonstrate that causal relations can be reconciled along global climate gradients, with diversity effects prevailing in the most productive environments, and abundance effects becoming dominant towards the most limiting conditions. These findings have major implications on climate change mitigation strategies aimed at carbon sequestration: we find that future nature-based mitigation solutions focused on fostering biodiversity will only be cost-effective in productive forest landscapes. In less productive environments, by contrast, mitigation measures should promote the abundance of locally adapted functional strategies. Conservation of species diversity in equatorial and tropical areas is thus a priority, not only to preserve the inherent value of biodiversity but also to achieve the global goals on atmospheric decarbonization. In less productive lands on Earth, the conservation of abundance through productivity should be posed, next to diversity, as a major element in environmental policies and land management.

 
The first full vector palaeosecular variation curve for Italy based on revised data from archaeological material and volcanic rocks
Authors: Tema Evdokia , Lanos Philippe
Published: March 2020

A new full-vector palaeosecular variation curve for Italy is presented based on a selection of high-quality data from sites within a 1000 km radius around Viterbo. The intensity and direction curves were calculated separately, using an updated compilation of Italian archaeomagnetic data from both archaeological material and volcanic rocks. The quality of the data was carefully evaluated, with particular attention on the reliability of the dating of the volcanic rocks and on the quality of the archaeointensity determinations. Only data from volcanic rocks of undisputable age have been considered. The new curves were calculated using Bayesian statistics and cover the last three millennia. The directional curve is very well constrained whilst the intensity curve is characterized by a larger error envelope, highlighting the need for new high-quality intensity data from Italy. Despite the limited number of reference data, the Italian intensity curve confirms periods with high intensity values of around 80 μT at 800-700 BC and 700-800 AD, in accordance with the geomagnetic intensity spikes previously identified in Middle East and Western Europe. Thanks to the privileged geographical position of the Italian peninsula, situated almost in the center of the Mediterranean, the Italian secular variation (SV) curves were used to analyze the evolution of the geomagnetic field in Europe by comparing them with other recently published SV curves for Western and Eastern Europe and with geomagnetic field models. The new curves can be used for archaeomagnetic dating not only in Italy but also in other countries of Europe such as Croatia, Slovakia and Serbia where no local SV curves are available so far.
New CGMW Tectonic Map of the Arctic
Authors: Petrov Oleg , Pubellier Manuel , Morozov Andrey , Kashubin Sergey , Shokalsky Sergey , Pospelov Igor
Published: March 2020

In 2019, the compilation of the new Tectonic Map of the Arctic (Tectonic Map of the Arctic, 2019: eds. O. Petrov, M. Pubellier) was completed. The map was compiled under the international project Atlas of Geological Maps of the Circumpolar Arctic, 1:5M with the participation of representatives of all Arctic states under the auspices of the Commission for the Geological Map of the World at UNESCO. The new 1:5M Tectonic map of the Arctic is a GIS project, which provides a transition to three-dimensional geological mapping of the Arctic. The project includes the crustal and sedimentary cover thickness maps, the crustal types map, the tectonic zonality map of the basement, schematic  map of key igneous provinces of the Circum-Arctic region and the geological transect compiled taking into account the latest scientific geological and geophysical data accumulated in recent decades as a result of high-latitude expeditions and scientific programs to substantiate the extended continental shelf in the Arctic. The new Tectonic map of the Arctic proved the continental nature of the Central Arctic Uplifts as a natural geological extension of Eurasia. Close structural relationships of deep-water parts of the Central Arctic and the shallow continental shelf of Northern Eurasia are substantiated by geological and geophysical characteristics of the consolidated crust, the upper mantle and sedimentary cover, as well as the common parameters of the magnetic and gravitational potential fields.
Stability analysis and tsunamigenic mass-failure scenarios in Palinuro volcano complex, Tyrrhenian sea
Authors: Gallotti Glauco , Ventura Guido , Armigliato Alberto , Zaniboni Filippo , Pagnoni Gianluca , Wang Liang , Passaro Salvatore , Sacchi Marco , Tinti Stefano
Published: March 2020

The Palinuro volcanic chain is located nearly 80 km offshore the Campania coasts (Italy), in the southern sector of the Tyrrhenian Sea. As many as 15 distinct volcanic edifices have been recently detected that covers a 90 km long and 20 km wide belt. The associated volcanism is still poorly understood but the presence of shallow seismicity and active hydrothermal activity suggest that this large volcanic complex is still active. Specific sectors of the chain show the presence of ongoing slope instability and thus the chance of mass movements cannot be ruled out in case of seismic or volcanic activity. In this work, a stability analysis for typical seismic loads in such a volcanic area has been performed through a revised limit equilibrium approach. In the revealed weaker sections, three mass failures of different scales have been reconstructed and their motion has been calculated by means of numerical models. The tsunami produced by each slide has been simulated, and considerable waves have been found in two of the three hypothesized scenarios. For the biggest slide of 2.4 km3, waves as high as 10 m could reach portions of the Calabria coasts with consequent hazardous impact.

This study belongs to a series of works focused on the volcanoes of the Tyrrhenian Sea that are very many and still poorly investigated. Considering scenarios involving mass movements of different sizes with distinct characteristics and based on geomorphological features seems to be a viable strategy to evaluate the tsunami hazard in the region.  
Pressure variations in the Monte Rosa nappe: new results from staurolite bearing metapelites
Authors: Vaughan-Hammon Joshua David , Luisier Cindy , Schmalholz Stefan , Baumgartner Lukas
Published: March 2020

Pressure recorded in metamorphic rocks is typically assumed to represent a hydrostatic stress and thus depends linearly on depth. Recently, work in the Monte Rosa nappe in the western Alps has challenged this lithostatic assumption. Observable pressure differences of 0.8 ± 0.3 GPa between chloritoid, talc, and phengite-bearing lithologies (locally known as ‘whiteschists’) at ca. 2.2 - 2.5 GPa, and metagranite lithologies at 1.4 – 1.6 GPa have been recorded. These pressure variations, rather than being attributed to variable rock kinetics, partial retrogression, or tectonic mixing, have been interpreted to be mechanically induced. As part of this ongoing investigation, we will present work undertaken on newly discovered staurolite-chloritoid bearing metapelites belonging to the Monte Rosa basement, in order to constrain the peak pressure and temperature conditions during burial within the Alpine orogeny and the resulting tectono-metamorphic and geodynamic implications.

Metapelitic samples from the Monte Rosa basement show a rich polymetamorphic history from high-T Variscan garnet growth through to high-P Alpine equilibration and decompression. Extensive phase petrology calculations have been undertaken on staurolite + chloritoid + phengite + paragonite assemblages, as well as garnet + chlorite + phengite + paragonite assemblages, representing equilibration at peak Alpine conditions. Various mixing models were employed due to non-negligible amounts of ZnO recorded in staurolite (~5% wt% and ~1 a.p.f.u) and the lack of available solution models. These result in peak Alpine conditions of 1.6 ± 0.2 GPa and 580 ± 15 ºC. These findings confirm the presence of significant disparities in pressure of 0.6 ± 0.2 GPa within the coherent Monte Rosa nappe.

Vital for the reconstruction and tectonic history for the western Alps is the maximum burial depth of units involved. We argue that the maximum burial depth of the Monte Rosa unit was significantly less than 80 km (based on the lithostatic pressure assumption and minor volumes of whiteschist at > 2.2 GPa). Rather, the maximum burial depth of the Monte Rosa unit was presumably equal or less than ca. 60 km, estimated from pressures of 1.4 - 1.6 GPs recorded frequently in metagranite and metapelitic lithologies. This depth is compatible with burial and exhumation within an orogenic wedge, rather than a complex exhumation mechanism such as within a weak and long subduction channel. Equally, the relatively slower exhumation rates from shallower crustal depths fit more reasonable tectonic velocities.
Experimental and numerical study of the resonant feature of internal gravity waves in the case of ‘dead water’ phenomenon
Authors: Medjdoub Karim , Jánosi Imre M. , Vincze Miklós
Published: March 2020

 ‘Dead water’ phenomenon, which is essentially a ship-wave in a stratified fluid is studied experimentally in a laboratory tank. Interfacial waves are excited by a moving ship model in a quasi-two-layer fluid, which leads to the development of a drag force that reaches the maximum at the largest wave amplitude in a critical ‘resonant’ towing speed, whose value depends on the structure of the vertical density profile. We utilize five ships of different lengths but of the same width and wet depth. The experimental analysis focuses on the variability of the interfacial wave amplitudes and wavelengths as a function of towing speed in different stratifications. Data evaluation is based on linear two- and three-layer theories of freely propagating interfacial waves and lee waves. We observe that although the internal waves have considerable amplitude, linear theory still gives a surprisingly adequate description of subcritical to supercritical transition and the associated amplification of internal waves.
Morphology in time and space: how does shape change with sequence stratigraphic architecture?
Authors: Sclafani Judith , Christie Max , Cone Marjean , Roselle Brooke , Bourne Audrey , Gazze Caroline , O'Brien Monika
Published: March 2020

In their seminal work on stratigraphic paleobiology, Patzkowsky and Holland highlighted the need for more morphological data that are placed within a stratigraphic context in order to more robustly study the impact of environmental change on morphological disparity. The ability to collect morphological data within sequence stratigraphic architecture has been limited by technique. As a result, most morphological data are collected from museum specimens, usually without sequence stratigraphic information. We used the photogrammetry technique, Structure-from-Motion, to collect brachiopod morphological data from outcrops in the Late Ordovician Cincinnati Arch (Indiana, Ohio, Kentucky; USA) and quantify morphological change within an established sequence stratigraphic architecture.

SfM uses 2D photographs taken from different angles to reconstruct a 3D shape. We photographed external valves of brachiopods in the field in 360 degrees (approximately 24 photos per specimen) and used the SfM software ‘Agisoft Metashape’ to make 3D models of those specimens. We exported these models into R and used the package ‘geomorph’ to generate a set of semi-landmarks. We used these to create a morphospace to explore the effects of environment and time on 3D shape.

Results indicate that brachiopod shells separate in morphospace according to their degree of inflation and roundness. These differences are likely controlled by environmental conditions at each position along a water depth gradient. Additionally, our results are consistent with the previously observed breakdown of the environmental gradient in response to the Richmondian invasion. In particular, for the genera Rafinesquina and Cincinitina, pre-invasion specimens inhabit a larger proportion of morphospace, with more specimens exhibiting an ovular outline. Post-invasion specimens contract in morphospace, exhibiting a more rectangular shape. However, Cincinitina is missing from the offshore environment in the C2 sequence and the deep subtidal environment in the C5 sequence, making it difficult to distinguish the effects of invasion from ecophenotypic variation.

Ultimately, our study demonstrates that SfM makes gathering 3D morphological data from the field possible. Because this is a low-cost and easily accessible method, possibilities of applying it more broadly within paleobiology abound. Further development of this technique will not only provide a better understanding of the distribution of morphological form within stratigraphic architecture, but also increase the quantity of morphological data from key intervals throughout the Phanerozoic. These data can be stored as a digital archive that could facilitate large-scale meta-analyses as well as education and outreach activities.
Soil Cohesion Development under Different Pore and Size Characteristics
Authors: Temiz Cagla , Ari Fikret , Deviren Saygin Selen , Arslan Sefika , Unal Mehmet Altay , Erpul Gunay
Published: March 2020

Soil cohesion (Co) is one of the most important physical soil characteristics and it is closely related to the basic soil properties and physical distribution forces (e.g. particle size distribution, pore sizes, shear strength) and so it is mostly determined by experimentally approaches with the help of other soil properties in general terms. Instead of using these assumptions, the fluidized bed approach provides an opportunity for direct measurement of intrinsic soil cohesion. In this study, soil cohesion development for different soil types was investigated with the fluid-bed method by which pressure drop in soil mass measures under increasing water pressures until the cohesion between particles disappears. For this purpose, 20 different soils varying with a wide range of relevant soil physical properties were sampled; such that clay, silt and sand contents varied between 2% and 56%, 1% and 50%, and 1% and 97%, respectively while porosity values were between 0.38 and 0.92. By those textural diversities of the soils, obtained cohesion values changed between 5203 N m-3 and 212276 N m-3. Given results from regression analysis, a significant relationship was found between cohesion values of the soils and their porosity and silt fractions (R2: 86.6).These findings confirm that the method has a high potential to reflect differential conditions and show that soil cohesion could be modeled by such basic and easily obtainable parameters as particle size distribution and porosity, as well. 

Key words; Mechanical soil cohesion, particle size distribution, fluidized bed approach, porosity
Satellite remote sensing techniques for detection of riverine and other sources flows in the coastal part of the Black Sea
Authors: Gancheva Irina , Campbell Gordon , Peneva Elisaveta
Published: March 2020

Poorly treated or completely untreated sewage water discharges are common problem which might have major consequences in coastal water regions, smaller water basins and semi-enclosed seas. Although satellite remote sensing has a great potential for coastal water quality monitoring such outfalls are difficult for detection due to the small scale of the events and the complex effects on the physical and biogeochemical parameters. In search for an appropriate technique for detection of  sewage discharges through satellite remote sensing, we examine areas with similar optical water properties, such as small river plumes flowing into the sea. They are expected to be visible in a similar manner as they have high turbidity levels, higher nutrients concentration and are fresh compared to the salty sea water.

In the current study we examine small river inflows in the Black Sea as they have optical and radar properties comparable with poorly or completely untreated sewage discharges in the region. Additionally, the Black Sea is an intriguing study area because of the unique ecosystem with challenging optical properties and water characteristics.

The temporal and spatial variability of the inherent optical properties and sea surface roughness are studied in the area of river plumes and are compared with open sea values. The impact of atmospheric conditions given by wind speed, wind direction and precipitation on the river plume detectability is observed in the regions of interest. Long time series of images for three years are analysed in order to reveal the seasonal and annual variability of the events. The satellite data is taken from the Sentinel missions and the atmospheric variables are from the ERA5 reanalysis.

The outcome of the study gives a solid base for estimation of the potential of satellite remote sensing for monitoring of poorly treated or completely untreated sewage outfalls or other land sources flowing into the sea.
Small-scale volcanic aerosols variability, processes and direct radiative impact at Mount Etna during the EPL-RADIO/REFLECT campaigns
Authors: Sellitto Pasquale , Salerno Giuseppe , La Spina Alessandro , Caltabiano Tommaso , Scollo Simona , Boselli Antonella , Leto Giuseppe , Zanmar Sanchez Ricardo , Sannino Alessia , Crumeyrolle Suzanne , Hanoune Benjamin , Giorio Chiara , Giammanco Salvatore , Roberts Tjarda , di Sarra Alcide , Legras Bernard , Briole Pierre
Published: March 2020

The aerosol properties of Mount Etna’s passive degassing plume and its short-term processes and radiative impact were studied in detail during the EPL-RADIO/REFLECT campaigns (summer 2016, 17 and 19), using a synergistic combination of remote-sensing and in situ observations, and radiative transfer modelling. Summit observations show extremely high particulate matter concentrations, with no evidence of secondary sulphate aerosols (SA) formation. Marked indications of secondary SA formation, i.e. by the conversion of volcanic SO2 emissions, are found at larger spatial scales (<20 km downwind craters). Using portable photometers, the first mapping of small-scale spatial variability of the average size and burden of volcanic aerosols is obtained, as well as different longitudinal, perpendicular and vertical sections. A substantial variability of the plume properties is found at these spatial scales, revealing that processes (e.g. new particle formation and coarse aerosols sedimentation) are at play, which are not represented with current regional scale modelling and satellite observations. Vertical structures of typical passive degassing plumes are also obtained using observations from a fixed LiDAR station constrained with quasi-simultaneous photometric observations. These observations are used as input to radiative transfer calculations, to obtain the shortwave top of the atmosphere (TOA) and surface radiative effects of the plume. Moreover, the radiative impact of Mount Etna’s emissions is studied using a medium-term time series (a few months during summer 2019) of coupled aerosol optical properties and surface radiative flux at a fixed station on Etna’s eastern flank. These are the first available estimations in the literature of the radiative impact of a passive degassing volcanic plume and are here critically discussed. Cases of co-existent volcanic aerosol layers and aerosols from other sources (Saharan dust transport events, wildfire from South Italy and marine aerosols) are also presented and discussed.
The downward propagation of split- and displacement-type SSWs in an idealised model
Authors: White Ian , Garfinkel Chaim , Gerber Edwin , Jucker Martin
Published: March 2020

Sudden stratospheric warmings (SSWs) have a significant downward influence on the tropospheric circulation below, although the mechanisms governing this downward impact are not well understood. It is also not known if the type of SSW event – be them splits or displacements – play a role in determining the magnitude of the tropospheric response. We here examine the impacts of split- and displacement-type SSWs on the troposphere.

To do this, we use the recently developed model of an idealised moist atmosphere to impose zonally-asymmetric warming perturbations to the extratropical stratosphere, extending the work of a recent study by the authors in which a zonally-symmetric heating perturbation was imposed. This model of ‘intermediate complexity’ is particularly suited to this study as it incorporates the radiation scheme that is utilised by operational forecast systems, including both the ECMWF and NCEP. The radiation scheme also allows us to force the model with a realistic ozone profile, and thus to simulate realistic radiative timescales in the stratosphere. From a control run with a realistic climatology, we perform an ensemble of spin-off runs every January 1st with imposed high-latitude stratospheric heating perturbations of varying degrees of magnitude. The heating perturbation is switched on for a limited period of time to mimic the sudden nature of a SSW event and the troposphere is allowed to evolve freely. We compare the evolution of the tropospheric response to the forced split and displacement-type SSWs with free-running SSWs of the same type in the control run.

By modifying only the temperature tendency equation as opposed to the momentum budget, our experiments allow us to isolate the tropospheric response associated with changes in the polar-vortex strength (e.g., a direct or indirect modulation of planetary waves and synoptic waves), rather than due to any planetary-wave momentum torques that initially drive the SSW. Nevertheless, the imposition of wave-1 and wave-2 heating perturbations provide a more realistic post-onset SSW state than that which occurs in response to zonal-mean heating perturbations as performed in our previous study.
Why do triangle zones exist? Insights from numerical models
Authors: Hegyi Betti , Erdos Zoltan , Huismans Ritske S. , von Hagke Christoph
Published: March 2020

Triangle zones in fold and thrust belts are enigmatic structures bound by foreland verging thrust zones and back-thrusts verging towards the hinterland. The geometry as well as kinematic evolution of these structures has been the subject of a wide range of studies over the last few decades. The understanding of triangle zone mechanics is incomplete although different driving mechanisms for their formation have been proposed. So far few – mostly analogue – modeling studies have focused on understanding the primary factors controlling their formation. Factors suggested to have a first order control on the formation of triangle zones include the rheological properties of the detachment and overburden rocks, the thickness of the overburden rocks, syn-tectonic erosion and sedimentation rate, fluid over-pressure conditions, and the angle of the detachment. Here we use the arbitrary Lagrangian-Eularian finite element code FANTOM to examine the development of triangle zones. We focus especially on the effect of the angle and rheology of the detachment, the rheology of the overburden strata, and syn-tectonic deposition. 
Uncertainty in coastal flooding: modelling and visualisation
Authors: Maskell John
Published: March 2020

Two case studies are considered in the UK, where uncertainty and drivers of coastal flood risk are explored through modelling and visualisations. Visualising the impact of uncertainty is a useful way of explaining the potential range of predicted or simulated flood risk to both expert and non-expert stakeholders.

Significant flooding occurred in December 2013 and January 2017 at Hornsea on the UK East Coast, where storm surge levels and waves overtopped the town’s coastal defences. Uncertainty in the potential coastal flooding is visualised at Hornsea due to the range of uncertainty in the 100-year return period water level and in the calculated overtopping due to 3 m waves at the defences. The range of uncertainty in the simulated flooding is visualised through flood maps, where various combinations of the uncertainties decrease or increase the simulated inundated area by 58% and 82% respectively.

Located at the mouth of the Mersey Estuary and facing the Irish Sea, New Brighton is affected by a large tidal range with potential storm surge and large waves. Uncertainty in the coastal flooding at the 100-year return period due to the combination of water levels and waves is explored through Monte-Carlo analysis and hydrodynamic modelling. Visualisation through flood maps shows that the inundation extent at New Brighton varies significantly for combined wave and surge events with a joint probability of 100 years, where the total flooded area ranges from 0 m2 to 10,300 m2. Waves are an important flood mechanism at New Brighton but are dependent on high water levels to impact the coastal defences and reduce the effective freeboard. The combination of waves and high-water levels at this return level not only determine the magnitude of the flood extent but also the spatial characteristics of the risk, whereby flooding of residential properties is dominated by overflow from high water levels, and commercial and leisure properties are affected by large waves that occur when the water level is relatively high at the defences.