bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-phase volcanisms along a stretched continental crust: insights from Xisha massif, northwestern of the South China Sea margin
Authors: Wang Lijie , Li Fuyuan , Zhang Baojin , Xu Ziying , Wang Zhe
Published: March 2020

Volcanism occurs close to the rifting active areas, especially in the passive continental margins. Their occurrence can have considerable impacts on the continental lithosphere breakup process, hydrocarbon accumulation system in a basin, and regional heat flows. The Xisha massif surrounded by two hyper-extended continental crust and three oceanic basins that the area is underlain by stretched continental crust in the northwestern South China Sea margin. Sporadic Cenozoic volcanic samples and structures from wells, seismic data, and multi-beam data in the Xisha massif have been previously recognized. This study focuses on describing the igneous structures and mapping the volcanic distributions. With the use of drilled wells with lithologic and stratigraphic information, 2D multiple channel seismic data, and multi-beam data, the occurrence of three phases Cenozoic volcanism were mapped. The first episodic volcanism during the rifting to spreading stage in the South China Sea occurred together with Mesozoic granitic pluton. The drilling samples in the well CK-2 show that Late Eocene to Early Miocene basaltic pyroclastic rocks beneath the thick Miocene reefal limestone. Only five mound shaped structures from seismic profiles located on the basement highs and entirely overlapped by the following carbonates. The second episodic volcanism occurred during Middle Miocene that features volcanic group, isolated volcanic mounds, lava flows, and hydrothermal vents associated with sills in the northwestern Xisha massif. The volcanic groups are mainly present above a NE-SW trended sag and the long axis trends NW, the same as the Middle Miocene active fault orientation in the Qiongdongnan basin. The volume of the largest volcanic group is ca. 504 km3. From the intruded strata and deformational structures of volcanic mounds, sills, and laccolith, we found the third episodic volcanism occurred during Pliocene on a small scale. The igneous bodies mainly distributed in the southern Xisha massif. Distribution and volume of igneous bodies show that Middle Miocene stage magmatic activity is more intense than the others, where volcanism is dominant. Comparing with tectonic stress filed, continental crust structures, and sediment thickness, we found the distribution of volcanos is probably related to NE-SW stretching stress filed during Middle Miocene. A high vertical pressure caused by 20-25 km’s crust thickness and only ca. 1-3 km thickness sediment layer may build a good vertical gradient for magma transport. We indicate the intense Middle Miocene volcanism in Xisha massif is also related to the high velocity layers in the lower crust and cased the high heat flows. These phenomena probably coincided with more magma intruded in the lower crust when plenty of post spreading magmatism emplacement in the SCS margin.
Ponding time, hydraulic conductivity and sorptivity – experimental determination by a single ring infiltrometer with rain simulator
Authors: Pelíšek Igor , Štibinger Jakub , Kulhavý Zbyněk , Melorio Luca
Published: March 2020

The continuous rain simulator used with very precise dosing enables both simulation of characteristic rainfall as well as accurate determination of infiltration rate and automatic calculation of hydraulic conductivity of soils under natural conditions. As a part of the research of infiltration processes induced by characteristic rainfalls, the effects of stormy rainfalls were verified in the described project stage. Stormy rain with constant intensity was applied by rain simulator in a single ring infiltrometer. Samples were tested in the laboratory (soils and kaolinite) and directly in the field. During rain infiltration was measured ponding time. Theoretical base of the research comes from non-steady state unsuturated vertical infiltration, which process (in one-dimensional flow conditions) can be described by Richard´s equation. Final simplified solution is provided by Philip´s simplified infiltration equtions. Hydraulic conductivity K was approximated from the analysis of time series of the process of vertical non-steady cumulative infiltration, going after ponding time. Sorptivity S was calculated by the numerical experiment with known values of stormy rain intensity, ponding time and hydraulic conductivity. Compared to traditional methods (single or double ring infiltrometer), soil hydro-physical characteristic (K, S) determined by this method is more reliable, informative and verified by ponding time.
Does permafrost matter? Permafrost related studies of conifer tree-ring growth in northern Siberia
Authors: Kirdyanov Alexander , Prokushkin Anatoly , Knorre Anastasia , Churakova (Sidorova) Olga , Fonti Marina , Saurer Matthias , Siegwolf Rolf , Reinig Frederick , Nikolaev Anatoly , Kolmogorov Alexey , Shishov Vladimir , Piermattei Alma , Krusic Paul , Büntgen Ulf
Published: March 2020

The world’s largest terrestrial biome, Boreal forest, is prone to the greatest rates of recent and predicted warming. Much of this circumpolar vegetation belt is underlain by permafrost, which further challenges our understanding of the direct and indirect consequences of increasing temperature on the functioning and productivity of these northern latitudinal forests.

Here, we present the results of an on-going study of tree-ring growth of conifers in Russia’s continuous permafrost zone in northern Siberia, from 61-72°N and 90-148°E. Tree-ring data from a variety of habitats between 20 and 600 m asl with different climate and thermo-hydrological regimes of soils are analyzed. While in some cases up to 60-70% of the year-to-year tree-ring width and maximum latewood density variability can be explained by summer temperature variations alone, we find that the seasonal dynamics of permafrost also plays an important role in defining the overall rate of radial tree growth. Wider rings are generally formed on sites with a deeper active soil layer, which itself depends on the geographical location of a site, as well as its ground vegetation, stand parameters and fire history. Waterlogged permafrost may further act as a source of water for trees under exceptionally dry summer seasons.

Our study indicates that the growth response of conifers to temperature and precipitation across the continuous permafrost zone of Siberia is both, site- and species-specific. This implies a range of possible scenarios of further development of northern forests under projected climate change. Seasonal dynamics of the active soil layer and possible permafrost degradation must be taken into account when modelling tree growth variability and forest productivity.
Exploitation of the maximum potential of fluorescence spectroscopy for water resource systems using Bayesian statistical approaches
Authors: Peer Sandra , Zoboli Ottavia , Vybornova Anastassia , Krampe Jörg , Zessner Matthias
Published: March 2020

Fluorescence Spectroscopy is a very promising tool for the identification of dissolved organic material (DOM) in aquatic systems. It is rapid, sensitive and relatively inexpensive. Knowledge gaps and challenging interpretation of large and complex datasets are currently hindering the full exploitation of its potential. To cite only few of the most crucial challenges, different fluorophores can contribute to overlapping peaks in the Excitation Emission Matrix (EEM), peaks can be shifted or their intensity can be reduced or enhanced through different environmental factors, and more powerful data processing tools are required. EEM data are typically analyzed by means of Parallel Factor Analysis (PARAFAC), which is a powerful technique that will also be applied here. Nevertheless, PARAFAC and similar analytical tools have a range of limitations. Therefore, we propose to develop and test a novel systemic approach and Bayesian statistical techniques to overcome existing obstacles. Contrary to the above mentioned, Bayesian statistics allow integrating prior information within the analysis in a transparent, formal and reproducible way. In this field, a vast body of knowledge and data has been gathered, which can be formalized in the form of priors and be included in the interpretation of data to make the analysis more powerful and robust. We will explore different applications in an EEM dataset consisting of samples from well-studied water systems with diverse characteristics covering spatial and temporal variability.
Colder and smaller : 10 years of observations of surface salinity by SMOS, Aquarius and SMAP to study mesoscale eddies in the Southern Ocean
Authors: Hasson Audrey , Pegliasco Cori , Boutin Jacqueline , Morrow Rosemary
Published: March 2020

Since 2010, space missions dedicated to Sea Surface Salinity (SSS) have been providing observations with almost complete coverage of the global ocean and a resolution of about 45 km every 3 days. The European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) mission was the first orbiting radiometer to collect regular SSS observations from space. The Aquarius and SMAP (Soil Moisture Active-Passive) missions of the National Aeronautics and Space Administration (NASA) then reinforced the SSS observing system between mid-2011 and mid-2015 and since mid-2015, respectively.

Using the most recent SSS Climate Change Initiative project dataset merging data from the 3 missions, this study investigates the SSS signal associated with mesoscale eddies in the Southern Ocean. Eddies location and characteristics are obtained from the daily v3 mesoscale eddy trajectory atlas produced by CLS. SSS anomalies along the eddies journey are computed and compared to Sea Surface Temperature (SST) anomalies (v4 Remote Sensing Systems) as well as the SubAntarctic Front (SAF) position (CTOH, LEGOS). The vertical structure of the eddies is further investigated using profiles from colocated Argo autonomous floats. 

This study highlights a robust signal in SSS depending on both the eddies rotation (cyclone/anticyclone) and latitudinal position with respect to the SAF. Moreover, this dependence is not found in SST. These observations reveal oceanic the interaction of eddies with the larger scale ocean water masses. SSS and SST anomalies composites indeed show different patterns either bi-poles linked with horizontal stirring of fronts, mono-poles from trapping water or vertical mixing changes, or a mix of the two.

This analysis gives strong hints for the erosion of subsurface waters, such as mode waters, induced by enhanced mixing caused by the deep-reaching eddies of the southern ocean.
Multi-Mission GNSS Radio Occultation Climate Data Records at the Jet Propulsion Laboratory
Authors: Oyola Mayra , Ao Chi , Verkhoglyadova Olga , Mannucci Anthony
Published: March 2020

Both the IPCC and the 2017 US Decadal Survey for Earth Science and Applications have recognized atmospheric profiling as an immediate priority, as proper representation of the Earth’s vertical atmosphere is imperative to close gaps in our understanding of processes that impact severe weather, air quality, and climate change. Radio Occultation (RO) techniques have been recognized for their uniqueness to provide reference datasets, triggering a growing interest in using RO for Climate and Weather applications.

 At the NASA Jet Propulsion Laboratory (JPL), physical parameters such as refractivity and derived atmospheric products (temperature, pressure, moisture) are obtained by applying inversion methodologies on the atmospheric delay induced on the occulted signal. Such multi-mission retrieval system has generated nearly two decades of observations and allowed the generation of Global Navigation Satellite Systems Radio Occultation (GNSS-RO) monthly gridded data for climate model evaluation and other applications (Obs4MIPS). 

We present an overview of data and methodology involved in producing Obs4MIPS GNSS-RO data, and show current improvements in the legacy products by comparison against the next generation of JPL’s monthly gridded data (Level 3) products.  Also, we evaluate the performance of the products against reanalysis datasets, and demonstrate its capability to detect climate signals and to improve our understanding of weather processes. Additionally, we will discuss ongoing activities associated with the incorporation of the recently launched COSMIC-2 data into our system.
Spatial anomalies of uranium background levels in groundwater of Lower Saxony
Authors: Stumpf Roland , Budziak Dörte , Deus Nico , Elbracht Jörg
Published: March 2020

Uranium is a trace metal yielding an average concentration in the Earth’s crust of about 2 to 4 mg/kg, and it occurs naturally in low levels in rock, soil, and water. Although widely known for its radioactive properties, at low levels dissolved uranium is more harmful by its chemical toxicity. The World Health Organisation (WHO) recommends a maximum concentration of 30 µg/l uranium in tap water, as well as a tolerable daily intake limit of 0.6 µg/kg body weight. Since 2011, tap water in Germany must not exceed uranium concentrations of 10 µg/l.

The uranium budget of the groundwater in Lower Saxony comprises mainly of geogenic input through water-rock interaction along the hydrological cycle and within the respective hydrogeological units, and possibly through century-old mining activities, and more recently the use of uranium bearing mineral fertilisers in farming. While the vast majority of uranium concentrations are significantly below 10 µg/l with many values below detection limit, some detached areas display elevated uranium with one confined maximum concentration of 124 µg/l. In order to determine uranium background values, statistical analyses accounted for hydrogeological units of the aquifer, land use, and well depths. Anomalous peak concentrations are unlikely to be a result of variations in geogenic background values alone and require further investigations. A possible rise of uranium concentrations caused by a downward shifting redox front, as proposed in other regions in Northern Germany, is yet to be identified in Lower Saxony.
Revisiting the deformation transients before the 2011 Tohoku-Oki Megathrust Earthquake with GPS
Authors: Socquet Anne , Marill Lou , Marsan David , Rousset Baptiste , Radiguet Mathilde , Burgmann Roland , Cotte Nathalie , Bouchon Michel
Published: March 2020

The precursory activity leading up to the Tohoku-Oki earthquake of 2011 has been suggested to feature both long- and short-term episodes of decoupling and suggests a particularly complex slow slip history. The analysis of the F3 solution of the Japanese GPS network suggested that an accelerated slip occurred in the deeper part of the seismogenic zone during the 10 years preceding the earthquake (Heki & Mitsui, EPSL 2013; Mavrommatis et al., GRL 2014; Yokota & Koketsu, Nat. Com. 2015). During the two months preceding the earthquake, no anomaly in the GPS position time series has been revealed so far, although several anomalous geophysical signals have been reported (an extended foreshock crisis near the future hypocenter (Kato et al., Science 2012), a synchronized increase of intermediate-depth background seismicity (Bouchon et al., Nat Geosc. 2016), a signal in ocean-bottom pressure gauges and on-land strainmeter time series (Ito et al., Tectonoph. 2013), and large scale gravity anomalies that suggest deep-seated slab deformation processes (Panet et al., Nat. Geosc. 2018 ; Wang & Burgmann, GRL 2019)).

We present novel results based on an independent analysis of the Japanese GPS data set. We perform a full reprocessing of the raw data with a double-difference approach, a systematic analysis of the obtained time-series, including noise characterization and network filtering, and make a robust assessment of long- and short-term tectonic aseismic transients preceding the Tohoku-Oki earthquake. An accelerated slip on the lower part of the seismogenic zone over the last decade is confirmed, not only below the epicenter of Tohoku-Oki earthquake but also further south, offshore Boso peninsula, which is a worrying sign of an on-going slow decoupling east of Tokyo. At shorter time-scale, first results seem compatible with a slow slip close to the epicenter initiating ~ 2 months before the mainshock.
An Experimental Study of the Systematic Underestimation of Wave Crests Measured by Lagrangian Buoys, and a Retrospective Correction Method
Authors: McAllister Mark , van den Bremer Ton
Published: March 2020

Wave-following buoys are used to provide measurements of free surface elevation across the oceans. The measurements they produce are widely used to derive wave-averaged parameters such as significant wave height and peak period, alongside wave-by-wave statistics such as crest height distributions. Particularly concerning the measurement of extreme wave crests, these measurements are often perceived to be less accurate. We directly assess this through a side-by-side laboratory comparison of measurements made using Eulerian wave gauges and model wave-following buoys for directionally spread waves representative of extreme conditions on deep water. Our experimental measurements are compared to exact (Herbers and Janssen 2016, J. Phys. Oceanogr, 46, 1009-1021) and new approximate expression for Lagrangian second-order theory derived herein. We derive simple closed-form expressions for the second-order contribution to crest height representative of extreme ocean waves. Our experiments confirm that the motion a wave-following buoy should not significantly affect the measurements of wave crests or spectral parameters, and that discrepancies observed for in-situ buoy data are most likely a result of filtering. This filtering occurs when accelerations that are measured by the sensors within a buoy are converted to displacements. We present an approximate means of correcting the resulting measured crest height distributions, which is shown to be effective using our experimental data.
GNSS data quality check in the EPN network
Authors: Fabian Andras , Bruyninx Carine , Legrand Juliette , .Miglio Anna
Published: March 2020

Global Navigation Satellite Systems (GNSS) are a widely spread cost effective technique for geodetic applications and monitoring the Earth’s atmosphere. Therefore, the density of the GNSS networks have grown considerable since the last decade. Each of the networks collects huge amounts of data from permanently operating GNSS stations. The quality of the data is variable, depending on the evaluated time period and satellite system. Conventionally, the quality information is extracted from daily estimates of different types of GNSS parameters such as number of data gaps, multipath level, number of cycle slips, number of dual frequency observations with respect to the expected number, and from their combinations.

The EUREF Permanent GNSS Network Central Bureau (EPN CB, Bruyninx et al., 2019) is operationally collecting and analysing the quality of more than 300 GNSS stations and investigates the main reason of any quality degradation. EPN CB is currently operating a semi-automatic (followed by a manual) data-monitoring tool to detect the quality degradations and investigate the source of the problems. In the upcoming years, this data-monitoring tool will be used to also monitor the GNSS component of the European Plate Observing System (EPOS) expected to include more than 3000 GNSS stations. This anticipated inflation of GNSS stations to be monitored will make it increasingly challenging to select the high quality GNSS data. EPN CB’s current system requires time-consuming semi-automatic inspection of data quality and it is not designed to handle the larger amounts of data. In addition, the current system does not exploit correlations between the daily data quality, time series and the GNSS station metadata (such as equipment type and receiver firmware) often common to many stations.

In this poster, we will first present the currently used method of GNSS data quality checking and its limitations. Based on more than 20 years of GNSS observations collected in the EPN, we will show typical cases of correlations between the time series of data quality metrics and GNSS station metadata. Then, we will set up the requirements and design the new GNSS data quality monitoring system capable of handling more than 300 stations. Based on the collected EPN samples and the typical cases, we will introduce ongoing improvements taking advantage of artificial intelligence techniques, show the possible design of the neutral network, and present supervised training of the neutral network.

Bruyninx C., Legrand J., Fabian A., Pottiaux E. (2019) GNSS Metadata and Data Validation in the EUREF Permanent Network. GPS Sol., 23(4), https://doi: 10.1007/s10291-019-0880-9
Dynamics and evolution of continental margin clinoform systems
Authors: de Jager Gerben , Harishidayat Dicky , Emmel Benjamin , Johansen Ståle Emil
Published: March 2020

Clinoforms are aquatic sedimentary features commonly associated with strata prograding from a shallower water depth into a deeper water depth. They are very sensitive to changes in water depth, rapidly moving along the shelf in response to sea level changes.  By reconstructing the initial clinoform geometry of buried clinoforms, an estimate of the paleo water depth (PWD) can be made. When this is done for several subsequent clinoform sets the amounts and rates of bathymetric changes can be calculated.

Here we present a novel approach to estimate clinoform parameters and depositional depths for continental margin clinoforms using seismic reflections, wellbore and biostratigraphy data. Seismic interpretation of three relatively east-west regional full-stack seismic reflection data from the continental margin of the western Barents Sea revealed twelve Late Cenozoic horizons. The clinoform shapes have been restored by removing the effects of compaction and flexural isostasy (backstripping). This includes the effects of glacial/interglacial scenarios on horizons with strong glaciomarine seismic indications.

Based on the reconstructed clinoform geometries we use empirical relationships from literature between clinoform geometry and depositional depth to estimate PWD values. In these analyses it is possible to estimate the PWD of the upper rollover point and the toe point by measuring the bottomset height, foreset height and topset height. A sensitivity analysis study has also been done on several different scenarios, varying elastic thickness, decompaction and net to gross ratio. Comparison with biostratigraphic water depth estimates indicate that PWD estimates revealed from clinoform parameters give reliable results.

Any mismatch between the backstripped PWD values and the PWD values derived from the clinoform geometry can then be attributed to geological processes not included in the backstripping process. Among others, these could be explained by rifting, thermal effects in the lithosphere, faulting or eustatic sea level changes. This allows the quantification of the magnitude of these large-scale crustal processes through time.

We will demonstrate that this method can further constrain the PWD on the continental margin clinoform system and thus can help to improve the understanding of the interplay between sedimentary processes and large-scale crustal processes. Furthermore, the PWD estimates will be a reliable input for further analysis of source-to-sink and stratigraphic forward modeling studies as well as reservoir and source rocks prediction on the petroleum development and exploration.

 
How pre- and syn-Hormuz formations were incorporated into the Zagros salt diapirs and reached the surface?
Authors: Tari Gabor , Gharabeigli Gholamreza , Majidi Abbas , Lovett Tam , Julapour Ali Asghar , Hinsch Ralph , Sellar Christopher , Kosi Walter
Published: March 2020

The southern Fars region of Iran is a classical and very well-studied area of salt tectonics for more than a century. Our study area is located in the “Simply Folded Belt” of the Zagros Mountains, including the nearby offshore of the Persian Gulf, and has a large number of well-known salt diapirs. These diapirs, composed of the infra-Cambrian Hormuz evaporites, have a surface diameter between 2-12 km and may extend vertically beneath the surface down to anywhere between 6-12 km.

In outcrop, the most striking aspect of these diapirs is the very large proportion of non-evaporitic rocks embedded within the evaporites. Also, these extraclasts (or megaclasts) are sometimes very large, reaching even the kilometer scale. We interpret their present-day dominance and ubiquitous „crowding“ in the outcropping apex of any given diapir as quite misleading as to their overall compositional contribution to these salt bodies. In our view, their seemingly large proportion in the internal make-up of the diapirs should be attributed to the preferential preservation of non-evaporitic rocks exposed on the surface. We argue that the real proportion of the overall non-evaporitic rocks within a typical Hormuz diapir could be as low as 1-2%, but certainly not more than 10%. Nevertheless, given their typical lithologies composed of crystalline basement, Eocambrian carbonates and sandstones with very high seismic velocities on the order of 5,000-5,500 m/s, the megaclasts may make the „dirty“ salt faster than the typical 4,500 m/s velocity of a typical “clean” rock salt sequence. These distinct crystalline and poorly dated Lower Paleozoic carbonate and clastic rocks found in the diapirs appear to have analogue formations outcropping only very far from the study area, like in Central Iran.

Importantly, as reported by others earlier, we have not found any evidence for the presence of post-Hormuz (i.e. post-Cambrian) host-rock lithologies incorporated into the diapiric material. Therefore, the strikingly selective nature of the extraclast lithologies within the diapiric bodies points to their original intra-Hormuz stratigraphic position. During Cenozoic diapirism, these infra-Cambrian Hormuz “stringers”, also including some pre-rift basement lithologies, were selectively incorporated into the ascending evaporite material as megaclasts and were carried to the surface from large depth. Therefore, one of the important conclusions of our study is that the various Hormuz intra-salt lithologic units must have deposited in a broad, wide-rift extensional setting.
Aerosol chemical composition and formation of secondary aerosol during haze events at the SORPES station in China
Authors: Wang Jiaping , Wang Jinbo , Nie Wei , Chi Xuguang , Wang Jiandong , Ding Aijun
Published: March 2020

Haze pollution is a serious air quality concern in China up to now, which occurs frequently in mega city clusters, e.g. Beijing-Tianjin-Hebei and Yangtze River Delta region, especially in the cold season. Understanding the dominating secondary aerosol formation processes is vital for improving the prediction and emission control strategy of haze pollution. In this study, we reported measurements of aerosol chemical composition using the soot particle aerosol mass spectrometer (SP-AMS) at a regional background station, the Station for Observing Regional Processes of the Earth System (SORPES), in Nanjing, eastern China. Characteristics of aerosol chemical composition and dominating secondary aerosol formation processes were analyzed during typical haze events and compared with that in clean episodes. Sources and transportation of organic aerosol were performed using positive matrix factorization (PMF) together with backward Lagrangian particle dispersion modeling (LPDM).
Water-sediment interaction in the Arno- and Tiber river catchments (central Italy)
Authors: Diendorfer Petra , Gozzi Caterina , Bauer Anna , Buccianti Antonella , Rantitsch Gerd , Scholger Robert , Nisi Barbara , Vaselli Orlando
Published: March 2020

The Tiber and the Arno river basins, represent the first (17,156 km2) and the second (8,228 km2) largest catchments in the peninsular Italy, respectively. The recent combined sampling (2017-2019)  of river waters and sediments in the heterogeneous geological environment of the Apennines enables the assessment of the geochemical and mineralogical interaction between bedrock, river sediments and water. The mineralogical and geochemical composition of the stream sediments are related to the corresponding lithological composition of the hydrological catchment, thus assessing physical weathering within the river basins. On the other hand, chemical weathering is assessed by the analysis of hydrochemical data from the Arno and Tiber rivers and their main tributaries. Locally, anthropogenic processes overprint the natural signature and the magnetic properties of the sediments provide effective data to map those areas. The application of multivariate robust statistical techniques on the combined dataset evaluates the water-sediment interaction and their spatial properties in central Italy. The main goal of this research is to investigate how the linkage between surface waters and steam sediments chemistry can be influenced by catchment-specific properties (e.g. landscape attributes, anthropic impact and climate) through an effective comparative analysis between two of the most important Italian watersheds.
Variations of surface waters characteristics in the Eastern Arctic Ocean in 2010-2019 at different scales: in situ and satellite study
Authors: Tarasenko Anastasiia , Supply Alexandre , Boutin Jacqueline , Kusse-Tiuz Nikita , Makhotin Mikhail , Ivanov Vladimir , Reverdin Gilles
Published: March 2020

The last 10 years of Arctic Ocean observations showed the dramatic changes and new records of the sea ice minimum. The largest variations were observed in the Eastern Arctic: the Kara, the Laptev, the East-Siberian seas. This region is a key area of the important freshwater input from the great Siberian rivers (Ob’, Yenisei, Lena). This remote area remains one of the less studied in the Arctic Ocean, although several regular expeditions (such as NABOS or Transdrift) together with special expeditions following the Northern Route, such as Tara-2013 expedition, or recent Transarktika-2019 expedition help to monitor the changes of surface waters in recent years.

The use of new satellite-derived datasets, (e.g., SST blended product from Danish Meteorological Institute or REMSS, SSS SMOS from LOCEAN University of Sorbonne) fill the gaps and help to better understand the complex dynamics of surface waters in the Eastern Arctic ocean.

In this work, we discuss the surface waters variations using in situ and satellite data at different scales.  Synoptic scales are studied with continuous and point in situ measurements (thermosalinographs and CTD data). The recent scientific results of Transarktika-2019 expedition are presented. In the summer season of 2019 (July-October) Transarktika expedition did oceanographic measurements following the Northern Route twice, from Vladivistok to Murmansk and back to Vladivostok. The seasonal variations are analyzed over the period of 10 years, comparing with climatological data. The difference between the climatological values of SST or SSS can reach 5 or more units in some areas of the Eastern Arctic. The results of interannual variations analysis using satellite data, suggest the salinification (“Atlantification”) of the southern areas and freshening of the northern parts of the Eastern Arctic.

The development of SSS SMOS Arctic product was supported by the French CNES-TOSCA SMOS-OCEAN project. Anastasiia Tarasenko, Nikita Kusse-Tiuz, Mikhail Makhotin and Vladimir Ivanov acknowledge financial support from the Ministry of Science and Higher Education of the Russian Federation, project RFMEFI61619X0108
Solute transport in dual conduit structure: experiment and modelling
Authors: Wang Chaoqi , Wang Xiaoguang , Majdalani Samer , Guinot Vincent , Jourde Hervé
Published: March 2020

An important phenomenon often encountered when interpreting tracer tests in karst aquifers is the occurrence of dual-peaked breakthrough curves (BTCs). The dual-peaked BTCs are usually attributed to tracer transport through a conduit system consisting of a dual-conduit structure: an auxiliary conduit that deviates from the main conduit at the upstream and converges back at the downstream. In order to understand how the geometric configuration of the dual-conduit structure influences the BTCs, laboratory experiments utilizing plastic tubes were conducted. The physical models were constructed by varying: 1) the total length of the conduits, while fixing the length ratio; 2) length ratio between the two conduits, while fixing the length of the main conduit; and 3) conduits connection angle. The tracer experiments are then fitted by a Multi-Region Advection Dispersion model and a Transfer Function model to derive effective transport parameters. This allows us to quantitatively compare the experimental results, and thus to analyse the conduit geometry effects on solute transport and to compare the performance of the two models.

Results show that the dual-conduit structure causes the double peaks of BTCs. Keeping the length ratio of the two conduits and increasing their total length leads to a larger separation of the two peaks of the BTCs. Keeping the length of main conduit while increasing the length of the secondary conduit causes similar effects. As (θ1-θ2) increases, the first peak concentration value decreases, the second peak concentration value increases.

Keywords: karst, lab experiment, dual-peaked BTCs, modelling
Variability in planktonic community caused by sub-mesoscale eddies and spatial features of the Baltic Sea coast
Authors: Kudryavtseva Elena , Bukanova Tatiana , Aleksandrov Sergey , Mosharov Sergey , Dmitrieva Olga , Melnik Anastasia , Krek Alexander , Ezhova Elena
Published: March 2020

Our study examines the features of photosynthetic processes that occurred in the coastal area of the south-eastern Baltic Sea during the advanced phase of intensive summer bloom of 2018. We aim for a better understanding of short-time variability in primary production coupled with planktonic composition and phytoplankton functional activity in relation to location of nutrients sources on the coast and sub-mesoscale eddies, which appear over the coastal slope of Cape Taran and move alongside the Sambia Peninsula coast. These two-day studies, conducted on board of research vessels, represent a snapshot of a highly variable ecosystem alongside the Sambia Peninsula and Curonian Spit at the end of summer. Satellite images of sea surface temperatures and chlorophyll «a» concentration were also used for identification of spatial variations and eddies; the circulation conditions were derived from the operational system SatBaltyk. Across the coastal area, the effects of physico-chemical conditions influenced the phytoplankton composition and photosynthetic activity. In the south, the hot weather as well as the impacts of the Vistula Lagoon and the Amber combine affected the increase of nutrients and caused the strongest cyanobacterial bloom. In the Cape Taran area, the plankton community was transformed as a result of sub-mesoscale eddies development. Substantial gradients of nutrients, composition, biomasses and functional activity of phytoplankton along transects through eddies field was shown.

Collecting of samples was done with a support of the state assignment of Shirshov Institute of Oceanology, Russian Academy of Sciences (topic no. 0149-2019-0013). Data processing was supported by the state assignment of Shirshov Institute of Oceanology, Russian Academy of Sciences (topic no. 0149-2019-0006) and RFBR grant ( no.19-05-50090).
Assessment of Rice Yield and Irrigation Water Demand Change in the Korean Peninsula based on RCP Climate Change Scenario
Authors: Lee Sujong , Lee Halim , Jo Hyun-Woo , Ko Youngjin , Lim Chul-Hee , Lee Woo-Kyun
Published: March 2020

In 2019, The Food and Agriculture Organization(FAO) announced that North Korea was a food shortage country and which is closely related to the agricultural drought frequency. These agricultural drought frequencies derived from global climate change are increasing and in terms of climate change, agricultural drought is not just a national problem, but a global scale issue. To respond to agricultural drought-related with food shortage, various studies and projects are conducted based on the remote sensing data and modeling such as hydrological model, crop model, but access to public data in North Korea is limited, and also objectivity is difficult to be guaranteed. In this study, the estimation of rice yield and irrigation water demand based on the RCP (Representative Concentration Pathway) climate change scenario was conducted using Environmental Policy Integrated Climate(EPIC) model which calculates various variables related to agriculture by using climatic data, Soil data and topographic data. For validating the parameter of the model, the study area was set to the Korean Peninsula and the parameter was set stepwise compared results of the model with South Korea national statistics. The results of rice yield and irrigation water demand in the Korean Peninsula was validated by using statistics of international organizations. The assessment of Rice Yield and Irrigation Water Demand Change based on the EPIC model is considered a method for complementing the field test and statistical limitations in North Korea. This study can be used as basic data for agricultural drought in North Korea and Based on the model results, it is necessary to concern food security.
Assessment of CO2-EOR and its geo-storage potential in oil reservoirs of Precaspian basin, Kazakhstan
Authors: Seisenbayev Nurlan , Abuov Yerdaulet , Tolenbekova Zhanat , Lee Woojin
Published: March 2020

Precaspian basin is the most petroliferous basin in Kazakhstan with more than 100 years of history of the oil and gas industry. The economy of the country has been depending on the revenues coming from the sale of Precaspian oil. Nevertheless, the average oil recovery rate in the country remains low around 30-35% and its government planned to increase the recovery rate to 55-60%. The high oil recovery rate could be achieved by enhanced oil recovery (EOR) methods by injecting diverse inert gases and liquids. The global challenge of excessive CO2 emissions makes an EOR with CO2 injection (CO2-EOR) a good candidate because the anthropogenic CO2 emission could be a good source of the injection gas. Depleted oil reservoirs are the first targets for the implementation of carbon storage. The basin contains 178 oil and gas fields distributed in pre-salt and post-salt sections divided by the huge Kungurian salt bed that deformed into domes throughout the basin. A set of suitable reservoir parameters (Original Oil In Place (OOIP), depth, API, pressure, porosity, permeability, initial oil saturation) for CO2-EOR have been identified by earlier works of researchers based on previous experience of the petroleum industry and used to screen the oil reservoirs of the Precaspian basin. Thirty-four reservoirs of the basin were identified to be suitable for CO2-EOR or CO2 storage. The effective CO2 storage capacity of the reservoirs has been estimated using the Carbon Sequestration Leadership Forum (CSLF) method. The previous estimation of the storage capacity of 178 reservoirs was 179.2 Mt of CO2 however, after the CO2-EOR screening, the capacity decreased to 24.4 Mt. The mapping of CO2 sources and investigation of CO2 amount released from each CO2 source in the Precaspian basin will contribute to the CO2 source-CO2 sink matching to decide the most feasible CCS options. In addition, the analysis of fault intensity and seismicity in suitable reservoir-seal pairs could have important implications for the safety of CO2 storage.
Reconciling multiphase reactivity of oleic acid with ozone using a kinetic flux model
Authors: Mattei Coraline , Shiraiwa Manabu , Pöschl Ulrich , Berkemeier Thomas
Published: March 2020

The ozonolysis of oleic acid on aerosol particles has been extensively studied in the past and is often used as a benchmark reaction for the study of organic particle oxidation. However, to date, no single kinetic model has reconciled the vastly differing reactive uptake coefficients reported in the literature that were obtained at different oxidant concentrations, particle sizes and with various commonly used laboratory setups (single-particle trap, aerosol flow tube, and environmental chamber). We combine the kinetic multi-layer model of aerosol surface and bulk chemistry (KM-SUB, Shiraiwa et al. 2012) with the Monte Carlo Genetic Algorithm (MCGA, Berkemeier et al. 2017) to simultaneously describe nine experimental data sets with a single set of kinetic parameters. The KM-SUB model treats chemistry and mass transport of reactants and products in the gas and particle phases explicitly, based on molecular-level chemical and physical properties. The MCGA algorithm is a global optimization routine that aids in unbiased determination of these model parameters and can be used to assess parameter uncertainty. This methodology enables us to derive information from laboratory experiments using a “big data approach” by accounting for a large amount of data at the same time.

We show that a simple reaction mechanism including the surface and bulk ozonolysis of oleic acid only allows for the reconciliation of some of the data sets. An accurate description of the entire reaction system can only be accomplished if secondary chemistry is considered and present an extended reaction mechanism including reactive oxygen intermediates. The presence of reactive oxygen species on surfaces of particulate matter might play an important role in understanding aerosol surface phenomena, organic aerosol evolution, and their health effects.

 

References

Berkemeier, T. et al.: Technical note: Monte Carlo genetic algorithm (MCGA) for model analysis of multiphase chemical kinetics to determine transport and reaction rate coefficients using multiple experimental data sets, Atmos. Chem. Phys., 17, 8021-8029, 2017.

Shiraiwa, M., Pfrang, C., and Pöschl, U.: Kinetic multi-layer model of aerosol surface and bulk chemistry (KM-SUB): the influence of interfacial transport and bulk diffusion on the oxidation of oleic acid by ozone, Atmos. Chem. Phys., 10, 3673-3691, 2010.
Machine learning for identification and counting of Naturally Occurring Asbestos
Authors: Selmaoui-Folcher Nazha , Galante-Gras Nathaël-Christian , Laporte-Magoni Christine , Turci Francesco , Petriglieri Jasmine Rita
Published: March 2020

Open-pit nickel mining is the main economic activity in New Caledonia. Lateritic Ni-ore deposits formed on weathered ultrabasic rock cover more than a third of the territory. However, among the mineral phases that make up these laterites, some belong to the asbestos family and have the capacity to emit pathogenic fibres. The inhalation of air polluted by such fibres may lead to severe respiratory diseases; asbestos may penetrate deep into the lungs causing at worst malignant mesothelioma.

In order to manage the natural occurrence of these fibres and take the necessary measures for the protection of workers, it is necessary to evaluate and monitor the concentration of asbestos fibres into the environment (e.g., airborne, waterborne). The current monitoring approach adopted by asbestos laboratories relies on counting method using Transmission Electron Microscopy (TEM), according to French regulation (NF X 43-050). Analysts operatively count and measure fibres and elongated mineral particles (EMPi) with on a filter viewed through the microscope device at high magnification. It is worth noting that analytical procedures involving electron microscopies are time-consuming, and show an intrinsic bias related to the subjectivity of operator analysis. These drawbacks explain the need to develop an automatic method for fibre and EMPi detection and quantification.

This paper presents a new method for detecting fibres on filters by using image processing and machine learning methods, discriminating single fibres, particles, juxtaposed objects and fibre bundles, minimizing as much image noise.
Phase and Amplitude Rayleigh Wave Fields Measured by AlpArray
Authors: Tesch Marcel , Meier Thomas
Published: March 2020

Using AlpArray and European networks, it is now possible to resolve the shape and inherent distortion of teleseismic surface waves across the greater alpine area at an as of yet unprecedented resolution. With well over 1500 available broadband stations within a 20° radius around the central Alps we demonstrate our approach for measuring both phase and amplitude distributions of surface wave signals in the space-frequency domain, leading to structural phase velocity information corrected for possible dynamic effects. Knowledge of the amplitude fields is particularly important to understand wave front deformations and to correct dynamic phase velocity measuremnts.

To diminsh the influence of noise, higher modes, coda waves, or adjacent events on our measurement, we analyse correlations with synthetic fundamental mode signals for a spherically symmetric earth model. The resulting wave field parameters are consequently expressed as amplitude and phase perturbations of the synthetic background wave fields. The measurements are explained and examples for phase and amplitude Rayleigh wave fields are shown and discussed.

Examining the wave field properties it becomes apparent that the dynamic contributions to the eikonal phase velocity are indeed significant, caused by both heterogeneities inside and (far) outside the observed region. Smaller local anomalies are for instance frequently observed around Mount Etna and Vesuvius, with the active vulcanism causing noticable reverberations. Surprisingly, large wave field anomalies are often oriented almost parallel to the propagation direction and can potentially span the entire station distribution, manifesting themselves as contiguous stripes of elevated amplitudes from positive interference of off-axis scattered waves.
Preindustrial to modern variability of sea surface temperatures and CO2 uptake in the South Pacific
Authors: Todorovic Sara , C. Wu Henry , K. Linsley Braddock , Kuhnert Henning , Dissard Delphine
Published: March 2020

The modern increase in atmospheric CO2 driven by fossil fuel combustion and land-use change is warming our atmosphere and surface oceans. The absorption of this excess CO2 by the oceans decreases seawater pH in a process known as ocean acidification (OA), which represents a threat to marine ecosystems with adverse impacts on coral health. It is important to understand how modern climate change impacts interannual and interdecadal climatic cycles and atmospheric phenomena which are originating in the Pacific and modulating global climate. There is a scarcity of data necessary to study the impacts of these changes on natural variability on longer timescales. In this study, we present multi-proxy (e.g. Sr/Ca, δ18O, δ13C, B/Ca) reconstructions of sea surface temperature (SST), surface seawater carbonate chemistry, with implications for pH variability of the South Pacific back to preindustrial times. This region of the Pacific is interesting for tracking the development of OA because of the well-constrained interannual to interdecadal SST and SSS variability from existing coral-based reconstructions. Massive corals (Porites sp.) from Rotuma and Tonga will be analyzed to extend the currently available SST reconstructions and expand the spatio-temporal coverage beyond the instrumental records. New monthly-resolved SST records will provide larger analyses exploring the influence of interannual and decadal-interdecadal climatic fluctuations on CO2 absorption and pH variation. We aim to quantify the anthropogenic impact on SST, pH and the ocean carbonate system to achieve a better understanding of the status in the South Pacific under open ocean conditions.