bluuebunny/crossref_metadata_2025 huggingface dataset:
A LSTM Neural Network for On-site Earthquake Early Warning
Authors: Wang Chia Yu , Huang Ting Chung , Wu Yih Min
Published: March 2020

On-site Earthquake Early Warning (EEW) systems estimate possible destructive S-waves based on initial P-waves and issue warnings before large shaking arrives. On-site EEW plays a crucial role to fill up the “blind zone” of regional EEW systems near the epicenter, which often suffers from the most disastrous ground shaking. Previous studies show that peak P-wave displacement amplitude (Pd) may provide a possible indicator of destructive earthquakes. However, the attempt to use a single indicator with fixed thresholds suffers from inevitable misfits, since the diversity in travel paths and site effects for different stations introduce complex nonlinearities. To overcome the above problem, we present a deep learning approach using Long-Short Term Memory (LSTM) neural networks. By utilizing the properties of multi-layered LSTM, we are able to train a highly non-linear neural network that takes initial waveform as input and gives an alert probability as the output on every time step. It is then tested with several major earthquake events, giving the results of a missed alarm rate less than 0.03 percent and false alarm rate less than 15 percent. Our model shows promising outcomes in reducing both missed alarms and false alarms while also providing an improving warning time for hazard mitigation procedures.
Tectono-stratigraphic evolution of the Aptian Pre-Salt of the onshore Espírito Santo Basin, SE Brazil, an example of proximal passive margin sag basin
Authors: Amarante Francyne Bochi do , Schilling André Basso , Kuchle Juliano , Iacopini David , Scherer Claiton Marlon dos Santos , Alvarenga Renata dos Santos , Ene Patrycia Leipnitz
Published: March 2020

The Espírito Santo Basin is part of the Brazilian rift system basins, formed by the break-up of the Supercontinent Gondwana and subsequent opening of the South Atlantic Ocean. The Aptian sedimentary succession of the basin is named Mucuri Member, lower unit of Mariricu Formation, and is contemporary to the pre-salt main carbonate reservoirs. Proximal deposition consists mostly of clastic sediments, interpreted as fluvial and coastal systems in the margins of a wide lake, which synchronously accumulated carbonates to the distal portions. The economic interest for oil is centered on the distal carbonates, thus the proximal sections lack detailed studies. The main objective of this study is the tectono-stratigraphic analysis of the marginal Mucuri Member. Leading methodology is seismic stratigraphy based on 220 2D lines and 1 3D volume, coupled with petrophysical and lithological analysis of 103 well log data and 5 cored wells. The combined analysis of seismic and lithological parameters resulted in the individualization of four seismic facies, which correspond to the predominance of one or two amongst five facies associations interpreted in cored wells. Seismic facies (SF) 1 is predominantly composed of offshore and lower shoreface successions; SF 2 is characterized by a dominance of poorly confined fluvial channels facies association; SF 3 records the interaction between fluvial and coastal successions composing mound-like structures, and is interpreted as wave-dominated deltaic facies association; SF 4 corresponds to sandspits structures and is restricted to regions where the coastal waves interact with basement highs. Four seismostratigraphic units were identified (named, from the base upwards: MUC1, MUC2, MUC3 and MUC4), delimited by three subparallel horizons. Unit-bounding reflectors coincide with gamma ray maxima or minima representing shales or anhydrites, respectively, deposited in deep water environments. The Mucuri Member records an enlargement in depositional area from the base upwards witnessing an overall lacustrine base level rise during deposition. The geometry of the depositional area during MUC1 and MUC2 was conditioned by the paleorelief of the preceding rift basins. MUC3 and MUC4 seismic units record a decrease in thickness as remnant topography was gradually filled; both units transcended and draped the half-grabens. The Early Cretaceous Mucuri Member composes the beginning of the post-rift sequence of Espírito Santo Basin, marked by the onset of thermal subsidence and cessation of mechanical subsidence.
Implementing FAIR principles for dissemination of data from the French OZCAR Critical Observatory network: the Theia/OZCAR information system
Authors: Braud Isabelle , Chaffard Véronique , Coussot Charly , Galle Sylvie , Cailletaud Rémi
Published: March 2020

OZCAR-RI, the French Critical Zone Research Infrastructure gathers 20 observatories sampling various compartments of the Critical Zone, and having historically developed their own data management and distribution systems. However, these efforts have generally been conducted independently. This has led to a very heterogeneous situation, with different levels of development and maturity of the systems and a general lack of visibility of data from the entire OZCAR-RI community. To overcome this difficulty, a common Information System (Theia/OZCAR IS) was built to make these in situ observation FAIR (Findable, Accessible, Interoperable, Reusable). The IS will allow the data to be visible in the European eLTER-RI (European Long Term Ecosystem Research) Research Infrastructure to which OZCAR-RI contributes.

The IS architecture was designed after consultation of the users, data producers and IT teams involved in data management. A common data model including all the requested information and based on several metadata standards was defined to set up information fluxes between observatories IS and the Theia/OZCAR IS. Controlled vocabularies were defined to develop a data discovery web portal offering a faceted search with various criteria, including variables names and categories that were harmonized in a thesaurus published on the web. The communication will describe the IS architecture, the pivot data model and open source solutions used to implement the data portal that allows data discovery. The communication will also present future steps to implement data downloading and interoperability services that will allow a full implementation of these FAIR principles.
All that glitters is not plastic: the case of open-ocean fibres
Authors: Suaria Giuseppe , Achtypi Aikaterini , Perold Vonica , Aliani Stefano , Pierucci Andrea , Lee Jasmine , Ryan Peter
Published: March 2020

Textile fibres are ubiquitous contaminants of emerging concern. Traditionally ascribed to the ’microplastics’ family, their widespread occurrence in the natural environment is commonly reported in plastic pollution studies, with the misleading belief that they largely derive from wear and tear of synthetic fabrics. Their synthetic nature has been largely used to motivate their persistence in the environment, thus explaining their presence in virtually all compartments of the planet, including sea-ice, deep-seas, soils, atmospheric fall-out, foods and drinks. As of today however, an extensive characterization of their polymeric composition has never been performed, even though the evidence that most of these fibres are not synthetic, is slowly emerging. By compiling a dataset of more than 916 seawater samples collected in six different ocean basins, we confirm that microfibres are ubiquitous in the world seas, but mainly composed of natural polymers. The chemical characterization of almost 2000 fibres through µFTIR techniques revealed that in striking contrast to global production patterns, only 8.2% of marine fibres are actually synthetic, with the rest being predominantly of animal (12.3%) or vegetal origin (79.5%). These results demonstrate the widespread occurrence of cellulosic fibres in the marine environment, emphasizing the need for full chemical identification of these particles, before classifying them as microplastics. On the basis of our findings it appears critical to assess origins, impacts and degradation times of cellulosic fibers in the marine environment, as well as to assess the wider implications of a global overestimation of microplastic loads in natural ecosystems.
Uncertainty in soil hydraulic properties parameterization and its propagation in vadose zone hydrological model output
Authors: de Jong van Lier Quirijn , Alves Rodrigues Pinheiro Everton
Published: March 2020

Vadose zone hydrological models employing finite difference numerical solutions of the Richards equation allow simulating the movement and predicting the state of soil water and associated quantities in the vadose zone. Nowadays, robust algorithms like Hydrus and SWAP are available to perform such simulations. Since most numerical issues with these algorithms have been solved, hydraulic parameters describing the relation between conductivity K, pressure head h and water content θ determine the quality of model output. Whichever method is used to obtain soil hydraulic properties, resulting parameters include an uncertainty, which may be expressed as a confidence interval. Existing correlations between parameters may be expressed in a correlation matrix. Using a stochastic approach, uncertainty and correlation may be considered in simulations and their propagation in results can be assessed. We developed a software which generates n stochastic realizations of the hydraulic parameter set considering uncertainty (standard error) and correlation matrix, runs the SWAP model for each realization and extracts the model output of interest. To apply the software and assess the propagation of uncertainties in the model output, hydraulic properties were measured in soils from south-east Brazil using inverse modeling of laboratory evaporation experiments, resulting in Van Genuchten parameter values, respective errors and correlations. These data were used to obtain n (n=104) stochastic realizations of deep drainage, runoff and evaporation in a bare-soil scenario. Similarly, for a pasture cropped scenario the water balance components (including transpiration), and relative yield were evaluated. The effect of uncertainty in these parameters on the mentioned output variables prediction is presented and discussed.
Impact of simulated deep-sea polymetallic nodule mining on sediment and pore-water geochemistry in prospective mining areas in the NE Pacific Ocean
Authors: Volz Jessica , Haffert Laura , Haeckel Matthias , Koschinsky Andrea , Kasten Sabine
Published: March 2020

Industrial-scale harvesting of deep-sea mineral resources, such as polymetallic nodules, is likely to have severe consequences for the natural environment. However, the effects of mining activities on deep‑sea ecosystems, sediment geochemistry and element fluxes are still poorly understood. Predicting the environmental impact is challenging due to the scarcity of environmental baseline studies and the lack of mining trials with industrial mining equipment in the deep sea. Thus, currently we have to rely on small-scale disturbances simulating deep-sea mining activities as a first-order approximation to study the expected impacts on the abyssal environment and ecosystem.

We have investigated surface sediments in disturbance tracks of seven small-scale benthic impact experiments, which have been performed in four European contract areas for the exploration of polymetallic nodules in the Clarion-Clipperton Zone (CCZ) in the NE Pacific Ocean. These small-scale disturbance experiments were performed 1 day to 37 years prior to our sampling program in the German, Polish, Belgian and French contract areas using different disturbance devices, such as dredges and epibenthic sledges. We show that the depth distribution of solid-phase Mn in the upper 20 cm of the sediments in the CCZ provides a reliable tool for the determination of the disturbance depth. We found that the upper 5–15 cm of the sediments were removed during various small‑scale disturbance experiments in the different contract areas. Transient transport‑reaction modelling for the Polish and German contract areas reveals that the removal of the surface sediments is associated with the loss of reactive labile organic carbon. As a result, oxygen consumption rates decrease significantly after the removal of the surface sediments, and consequently, oxygen penetrates up to tenfold deeper into the sediments inhibiting denitrification and Mn(IV) reduction. Our model results show that the return to steady state geochemical conditions after the disturbance is controlled by diffusion until the reactive labile TOC fraction in the surface sediments is partly re‑established and the biogeochemical processes commence. While the re-establishment of bioturbation is essential, steady state geochemical conditions are ultimately controlled by the burial rate of organic matter. Hence, under current depositional conditions, new steady state geochemical conditions in the sediments of the CCZ are reached only on a millennium-scale even for these small-scale disturbances simulating deep-sea mining activities.
Convection-Permitting Regional Climate Simulations over North America
Authors: Liu Changhai , Ikeda Kyoko , Rasmussen Roy
Published: March 2020

The NCAR Water System Program has been striving to improve the representation of the water cycle and its future changes in both regional and global models during the past decade. One of our efforts is conducting continental-scale convection-permitting simulations of the current and future climate of North America using the WRF model based atmospheric-hydrological coupling system. The major science objectives of these simulations are: 1) to evaluate the capability of convection-permitting WRF model in capturing orographic precipitation and snow mass balance over the western mountains of North America and convective precipitation in the eastern part of the continent; 2) to assess future changes in seasonal snowfall and snowpack and associated surface hydrological cycles under the CMIP5-projected global warming; 3) to investigate water cycle changes in response to climate warming, including the summertime convective precipitation and associated mesoscale convective storm tracks; and 4) to examine the impact of climate change on severe weather over North America. As such, two phases of convection-permitting climate modeling have been undertaken using 4-km horizontal grid spacing covering most of North America.

The phase-one effort involves two 13-year simulations as reported in Liu et al. (2017): 1) a historical simulation with initial and boundary conditions from ERA-interim, and 2) a future climate sensitivity simulation, called pseudo-global warming (PGW), with modified reanalysis-derived initial and boundary conditions by adding the CMIP5 ensemble-mean projected climate change. These WRF-downscaled climate change simulations provide a unique high-resolution dataset to the community for studying one possible scenario of regional climate changes and impacts.

Recognizing that only the thermodynamic future climate impacts can be adequately addressed in the PGW approach, the NCAR Water System team has started conducting a second set (phase II) of current and future simulations at 4-km grid spacing over North America. In these simulations, the WRF model is forced using the weather perturbations derived from the NCAR CESM model 6-hourly output plus the reanalysis-based bias-corrected CMIP5 ensemble mean climate as detailed in Dai et al. (2017). The model domain is also expanded northward to include Canada and the Canadian Arctic. Because storm track changes are permitted, these simulations complement the previous PGW simulations, allowing us to address the impact of dynamic changes in the future warmer climate. We will present some preliminary analysis results of these simulations, with focus on the evaluation of the historical simulation and the added value of convection-permitting resolution and mean climate bias corrections.
Gully erosion – the use of computer based landscape evolution models to predict initiation, growth and stabilisation
Authors: Hancock Greg , Willgoose Garry , Welivitiya Dimuth
Published: March 2020

Gully erosion is recognised as a significant environmental issue. It affects grazing, croplands as well as rangelands. Of particular interest here are mining landscapes which are comprised of unconsolidated waste material that has little or no economic value. These landscapes are new systems with little nutrients and plant growth potential and the materials are often highly erodible and prone to gullying. Many empirical and physical models have been developed to understand gully initiation, growth and stabilisation. Here we demonstrate the use of computer based landscape evolution models to quantify the gully process. These models use a digital elevation model to represent the landform and allow the landform to evolve through time. The models can operate at sub-hourly through to millennial time scales. The landform (and resultant gully) can be visualised and rates of movement quantified and erosion rates calculated.  Different land surface properties such as vegetation cover, armour as well as climate variability can be investigated at the hillslope, catchment and landscape scale. These models offer a huge advance in visualisation and quantification of gully evolution. The models have been used across a wide range of materials and climates and will be demonstrated using several mining case studies. Of particular interest for the mining industry is how surface properties change through time as armouring and weathering occurs and vegetation establishes. Model strengths will be highlighted and areas where advances, particularly field data needs will be discussed.
Sedimentological and limnological evolution of recreational lakes in a former asbestos mining region (Québec, Canada): insights from paleolimnology
Authors: Pienitz Reinhard , Jacques Olivier
Published: March 2020

The Bécancour River basin in southern Québec (Canada) has been impacted by more than a hundred years of asbestos mining activities in the Thetford Mines region. Several recreational water bodies located downstream from the city are suffering from high sediment and contaminant loads and eutrophication. In order to prepare an efficient management of the fluvial lakes, we completed paleolimnological investigations to evaluate the extent of their deterioration and identify catchment disturbances that influenced their present-day condition. Here we present the results of a multi-proxy study of sediment cores collected from a chain of 5 lakes. The sedimentary records from these lakes indicate severe perturbations associated with the complete draining of Lac Noir, a former lake near Thetford Mines excavated and drained for mining purposes between 1955-1959. Radiometric 210Pb dating revealed extreme increases in the sediment accumulation rate following this event. Analyses of loss-on-ignition, carbon (C) and nitrogen (N) isotopes, grain-size, and X-ray microfluorescence indicated that the post-1960 sediments were enriched in fine-grained mineral matter and had higher metal and nutrient concentrations as compared to older sediments at the bottom of the cores. Changes in the δ13C and C/N ratios and the predominance of diatom taxa (class Bacillariophyceae) typical of nutrient-rich waters (e.g., Cyclostephanos invisitatus, Cyclotella meneghiniana) also showed that the 1955-1959 event led to a rapid eutrophication of some lakes. Results from our study illustrate that the asbestos mining activities had dramatic impacts on lake biota and contaminant levels, and suggest that major restoration efforts will be needed to improve their ecological condition.
Mean and eddy kinetic energy of the Gulf Stream from multiyear underwater glider surveys
Authors: Todd Robert E.
Published: March 2020

Subtropical western boundary currents play a key role in ocean energy storage and transport and are characterized by elevated mean and eddy kinetic energy. Due to a lack of spatially broad subsurface observations of velocity, most studies of kinetic energy in western boundary currents have relied on satellite-based estimates of surface geostrophic velocity. Since 2015, Spray autonomous underwater gliders have completed more than 175 crossings of the Gulf Stream distributed over more than 1,500 km in along-stream extent between between Miami, FL (~25°N) and Cape Cod, MA (~40°N). The observations include roughly 14,000 absolute ocean velocity profiles in the upper 1000 m. Novel three-dimensional estimates of mean and eddy kinetic energy are constructed along the western margin of the North Atlantic at 10-m vertical resolution. The horizontal and vertical distributions of mean and eddy kinetic energy are analyzed in light of existing independent estimates and theoretical expectations. Observation-based estimates of mean and eddy-kinetic energy such as these serve as important metrics for validation of global circulation models that must adequately represent western boundary currents.
Two models and two emission databases – evaluation of the PM10 and PM2.5 concentrations modelled with WRF-Chem and EMEP4PL
Authors: Werner Małgorzata , Kryza Maciej , Dudek Justyna
Published: March 2020

Some European countries in Eastern or Central Europe, such as Poland, have serious problems with air quality. High concentrations of particulate matter (PM) in winter are often related to high coal and wood combustion for residential heating. Meteorological conditions, i.e. low air temperature and anticyclones, provide favourable conditions for the accumulation of air pollution, rendering it harmful to people.  PM concentrations during the warmer period are much lower, however there are episodes with elevated concentrations related to e.g. long-range transport of pollutants from biomass burning areas. Policy makers in Poland put a lot of effort to improve air quality as well as inform and aware people on harmful effects of air pollution. One of the relevant tools which provides information on the past, current and future state of the air pollution are chemical transport models.

In this study we aim for validation of PM10 and PM2.5 concentrations from two different chemical transport models – WRF-Chem and EMEP4PL and two different emission databases – a) a regional EMEP database, and b) a local database provided by the Chief Inspectorate of Environmental Pollution. Modelled PM10 and PM2.5 concentrations were compared with observations from Polish stations for the year 2018. The results show a clear seasonal variation of the models performance with the lowest correlation coefficients in summer. Higher seasonal variability is observed for WRF-Chem than EMEP, which is probably related to differences in calculations of boundary layer height. Application of local database improves the results for both models. For several months, the performance of WRF-Chem and EMEP is clearly different, which shows that an ensemble approach with an application of these two models could improve the modelling results. The differences in the model performance significantly influence the results of the population exposure assessment.

 
Landslide mapping, monitoring and early warning by using optical remote sensing, InSAR and ground-based sensors: case study of the Qingpo landslide (Wenchuan, China)
Authors: Zhao Weihua , Xie Mingli , Ju Nengpan
Published: March 2020

 Studies of landslide evolution that improve the knowledge of ground movements are essential to understand the mechanism of deformation for landslide-prone territories to mitigate the associated risk. The large Qingpo landslide, with a volume of about 200,0000 m3, is located in a mega ancient landslide (with a width of 1300 m and a height difference about 400 meters), and a pylon is just located on the boundary of Qingpo landslide. How to accurately judge the historical evolution process, current evolution stage and the future evolution trend of the large landslides is very important for landslide and pylon monitoring and early warning. In this study, on the basis of a detailed on-site investigation, a total of 114 Sentinel-1A Images over five years with Level-1 Single Look Complex (SLC) mode and Interferometric Wide (IW) acquisition mode were downloaded from Copernicus Open Access Hub and were preprocessed by time series InSAR model, which allow us to produce deformation time series and mean deformation velocity maps. An automatic monitoring and warning scheme was designed, 10 sets of ground-based sensors, containing self-adapting crack meter, rain gauge, strain gauge and dip meter were installed, followed by real-time monitoring within one month. Ultimately, the temporal and spatial evolution characteristics of the landslide were comprehensively analyzed through on-site deformation investigation, long-term deformation monitoring by InSAR and ground-based real-time monitoring. The applicability of long-term remote sensing monitoring and real-time monitoring methods and how to use them together have also been verified. This study may can also provide a typical case for the comprehensive use of multi-source data.
Temperature Annual Cycle Variation and Response to Solar Radiation during 1960 to 2016 in China
Authors: Zhao Runze , Wang Kaicun , Wu Guocan , Zhou Chunlue
Published: March 2020

The change of its annual cycle is extremely important due to global warming. A widely used method to analyze the changes of temperature annual cycle is based on the decomposition to phase, amplitude and baseline terms. Solar radiation as the leading energy source of temperature changes can directly influence temperature annual cycle. In this study, we investigate the phase, amplitude and baseline of temperature and solar radiation annual cycle after Fourier transform during 1960-2016 in China. The results show that annual cycle of maximum, minimum and mean surface air temperature are advancing in time (-0.08, -0.27 and -0.33 days per ten years), decreasing in range (-0.07, -0.25 and -0.18 degrees per ten years) and rising in baseline (0.20, 0.34 and 0.25 degrees per ten years). To further quantify the effect of surface solar radiation to temperature, we remove the effect from its original time series of maximum and mean temperature, based on a linear regression. The compare of raw and adjusted temperature shows that surface solar radiation advancing the time by 0.19 and 0.19 days per ten years, reduces the range by 0.14 and 0.13 degrees per ten years, and reduces the baseline by 0.08 and 0.04 degrees per ten years, for surface maximum and mean daily air temperature. The result can explain parts of seasonal temperature variation. Effect of surface solar radiation is most obvious Yunnan-Guizhou Plateau for maximum phase. The low phase value in this area is corrected and well-match with other same latitude area after adjusted.
Long-term trends and variations in haze-related stagnation intensity in North China during 1980-2018
Authors: Feng Jin
Published: March 2020

Recently, the climatological and environmental communities have paid significant attention to the long-term trends and variations in haze-related weather conditions in North China (NC). This study investigates the issue based on a quantified air stagnation index (ASIE) that combines the stagnation intensity with the background emissions, considering that haze occurrence strongly depends on the rate of emission. ASIE shows a close spatial and temporal relationship with the observed PM2.5 concentrations, and a strong sensitivity to haze occurrence in NC. The change in ASIE revealed an approximate 19% increase in the annual stagnation intensity over the period of 1980-2018, due to significant decreases in PBLH and ventilation potency. The interannual variations in stagnation intensity were very significant. The percentage change of ASIE was as high as 50-70% in some years. However, there was an apparent drop in stagnation intensity during 2013-2018, which possibly contributed to the recently reported improvement in aerosol concentration in NC. It also shows that such low-frequency oscillation occurred twice during 1980-2018. Hence, once the current trend of decreasing stagnation intensity changes, haze events may become more common in the future. Finally, we present a quick estimate for the emission reduction ratio that can balance the variations and trend of stagnation intensity using a simple linear model, which can be used to evaluate the difficulty of the “clean air challenge” in NC. The results suggest that the enforcement of the emission reduction plan should be tailored according to the stagnation conditions in the case study year and region.
Sensitivity of precipitation and structure of Typhoon Hato to bulk and explicit spectral bin microphysics schemes
Authors: shen xiaodian , cao qimin , jiang baolin , lin wenshi , zhang lan
Published: March 2020

This study simulated the evolution of Typhoon Hato (2017) with the Weather Research and Forecasting model using three bulk schemes and one bin scheme. It was found that the track of the typhoon was insensitive to the microphysics scheme, whereas the degree of correspondence between the simulated precipitation and cloud structure of the typhoon was closest to the observations when using the bin scheme. The different microphysical structure of the bin and three bulk schemes was reflected mainly in the cloud water and snow content. The three bulk schemes were found to produce more cloud water because the application of saturation adjustment condensed all the water vapor at the end of each time step. The production of more snow by the bin scheme could be attributed to several causes: (1) the calculations of cloud condensation nuclei size distributions and supersaturation at every grid point that cause small droplets to form at high levels, (2) different fall velocities of different sizes of particles that mean small particles remain at a significant height, (3) sufficient water vapor at high levels, and (4) smaller amounts of cloud water that reduce the rates of riming and conversion of snow to graupel. The distribution of hydrometeors affects the thermal and dynamical structure of the typhoon. The saturation adjustment hypothesis in the bulk schemes overestimates the condensate mass. Thus, the additional latent heat makes the typhoon structure warmer, which increases vertical velocity and enhances convective precipitation in the eyewall region.
Atlantic Salinity Pileup as a Remote Fingerprint of Weakening Atlantic Overturning Circulation under Anthropogenic Warming
Authors: Zhu Chenyu , Liu Zhengyu
Published: March 2020

Climate models show a weakening Atlantic meridional overturning circulation (AMOC) under global warming. Limited by short direct measurements, this AMOC slowdown has been inferred, with some uncertainties, indirectly from some AMOC fingerprints locally over the subpolar North Atlantic region. Here we present observational and modeling evidences of the first remote fingerprint of AMOC slowdown outside the North Atlantic. Under global warming, the weakening AMOC reduces the salinity divergence and then leads to a remote fingerprint of “salinity pileup” in the South Atlantic. Our study supports the AMOC slowdown under anthropogenic warming and, furthermore, shows that this weakening has occurred all the way into the South Atlantic.
The Bengal Fan sediment archive: a record of Himalayan tectonics, climate, and/or drainage routing change between source and sink?
Authors: Najman Yani , Blum Mike , Gleason Jamie , Rogers Kimberly , Orme Devon , Mark Chris , Barfod Dan , Carter Andy , Parrish Randy , Chew Dave , Gemignani Lorenzo
Published: March 2020

The Bengal Fan IODP Exp 354 core provides a Neogene re­cord of eastern and central Himalayan exhu­mation. U-Pb analyses of detrital zircons from this sediment archive shows that from ~ 4 Ma, there was a major increase in grains aged <300 Ma, indicating a major increase in contribution from the Trans-Himalaya (Blum et al., Nature SR, 2018). Detrital rutile U-Pb and detrital zircon fission track data from the same archive (Najman et al, GSAB 2019) indicates an approximately coeval increase in exhumation rate from the Eastern Himalayan Syntaxis. Thus an attractive explanation to explain the increase in Transhimalayan input may be that it was caused by initiation of exhumation of the syntaxis from beneath its Transhimalayan cover. However, a similar dataset obtained from the proximal foreland basin Siwalik deposits (Govin et al., in review) indicates an earlier onset to syntaxial exhumation, compared to that recorded in the distal sediment archive. We consider therefore whether climate change may be responsible for the increased Transhimalayan input: onset of Northern Hemisphere glaciation may have increased the proportion of erosion in the higher, glaciated, regions of the Transhimalaya, compared to that part of the orogen south of the suture zone. Analyses of Hf isotopic composition of detrital zircons to assess the possibility that drainage basin changes may explain the increase in material at 4 Ma, are ongoing. The difference in timing of the syntaxial exhumational signal between the proximal and distal archives may be the result of downstream dilution, or may result from sequestration of material on the shelf, with release to the deep ocean during sea level low stands.
Deep learning Q inversion from reflection seismic data with strong attenuation using an encoder-decoder convolutional neural network: an example from South China Sea
Authors: Zhang Hao , Han Jianguang , Zhang Heng , Zhang Yi
Published: March 2020

The seismic waves exhibit various types of attenuation while propagating through the subsurface, which is strongly related to the complexity of the earth. Anelasticity of the subsurface medium, which is quantified by the quality factor Q, causes dissipation of seismic energy. Attenuation distorts the phase of the seismic data and decays the higher frequencies in the data more than lower frequencies. Strong attenuation effect resulting from geology such as gas pocket is a notoriously challenging problem for high resolution imaging because it strongly reduces the amplitude and downgrade the imaging quality of deeper events. To compensate this attenuation effect, first we need to accurately estimate the attenuation model (Q). However, it is challenging to directly derive a laterally and vertically varying attenuation model in depth domain from the surface reflection seismic data. This research paper proposes a method to derive the anomalous Q model corresponding to strong attenuative media from marine reflection seismic data using a deep-learning approach, the convolutional neural network (CNN). We treat Q anomaly detection problem as a semantic segmentation task and train an encoder-decoder CNN (U-Net) to perform a pixel-by-pixel prediction on the seismic section to invert a pixel group belongs to different level of attenuation probability which can help to build up the attenuation model. The proposed method in this paper uses a volume of marine 3D reflection seismic data for network training and validation, which needs only a very small amount of data as the training set due to the feature of U-Net, a specific encoder-decoder CNN architecture in semantic segmentation task. Finally, in order to evaluate the attenuation model result predicted by the proposed method, we validate the predicted heterogeneous Q model using de-absorption pre-stack depth migration (Q-PSDM), a high-resolution depth imaging result with reasonable compensation is obtained.
Distribution and cause and cause analysis of typical soil microorganisms in alpine region
Authors: Wang Jianwei , Qin Tianling , Liu Fang , Nie Hanjiang , Lv Zhenyu
Published: March 2020

Abstract:

Soil microorganisms play an important role in the material cycle, especially in the alpine region where the ecological environment is fragile. Therefore, we selected a typical soil on slop for sampling in a sub-watershed upstream of the Yellow River Basin. Microbial species were detected by High-throughput sequencing. At the same time, the relevant physical ang chemical properties of the soil were also tested, such as mechanical composition, soil type, moisture content, TN, TP, pH, organic matter et al. Species and abundance of microorganism were calculated and analyzed by significance test regression analysis. The results showed that Nitrospira and Gaiella were the main microorganism. There was no obvious relationship between soil type and microorganism species. But soil moisture content had a significant effect on diversity of microorganism. There was a significant negative correlation between Bradyrhizobium and soil TN, and a negative correlation between Nitrospira and Nocardioides species abundance. This study provides a data basis for microbiological research in alpine regions, and also actively explores the characteristics of microbial distribution.
Probable reasons of Rock Sample Apparent Permeability Loss over Time in Long-term Measurements
Authors: Baryshnikov Nikolay , Zenchenko Evgeniy , Turuntaev Sergey
Published: March 2020

In the last few years, tight oil production has increased significantly. This is why the study of the filtration properties of low-permeable rocks (permeability near 1 mD) has acquired particular significance. Such rocks can be subject to considerable compaction during development, which manifests itself in the non-linear permeability loss in time at constant net confining stress. In the laboratory, the compaction (or creep) of porous rock samples under constant stress conditions was observed by many researchers for experiment durations ranging from several hours to several weeks. Conducting such lengthy flow experiments accompanies by a number of challenges. First of all, it is necessary to exclude factors not related to the deformation of the sample. In this study we analyzed possible causes of time trends observed under constant net confining stresses in long-term measurements of low-permeable sample permeabilities. Experimental study of flow in a limestone core sample was conducted. During the experiment with duration of 40 days, the fluid pumping was carried out in several stages with different constant values of the confining pressure and the pore pressure gradient. As a result, the permeability of the sample decreased by 10 times. It was shown that such significant decrease in the permeability in time can be caused by clogging of the sample pore space. The additional experiment with sequential pumping of single-phase gas and liquid through the sample showed that when pumping gas, the sample permeability remained almost constant most of the time. We propose that gas bubbles contained in the flow of liquid can act as a dispersed phase that clogs pores. The estimations show that even very low particle concentrations at large time periods lead to significant decrease in the permeability. The possibility of clogging of the core sample pore space must be considered when conducting the long-term experiments on study of the permeability by the steady-state method.
Upper mantle anisotropy beneath Sudetes from shear wave splitting - passive seismic experiment AniMaLS
Authors: Rewers Julia , Środa Piotr , Working Group AniMaLS
Published: March 2020

The passive seismic experiment AniMaLS was organized in 2017 in the Sudetes in Poland. One of the objectives was to study the anisotropy of the sub-crustal lithosphere and asthenosphere beneath the NE termination of the Bohemian Massif. Temporary seismic network of 23 broadband stations was operating in the area of Sudetes mountains and Fore-Sudetic Block, covering a ~200 x 100 km large area, with ~30 km spacing between stations. Obtained recordings were supplemented with data from permanent stations of Czech and Polish seismological networks located in the study area.

The Sudetes belong to internal zone of Variscan Orogen and are located in the NE part of the Bohemian Massif, between the Elbe Fault in SW and the Odra Fault in NE. The sudetic lithosphere represents a complex mosaic of several units with distinct histories of tectonic evolution and with consolidation ages ranging from the upper Proterozoic to the Quaternary. The aim of the project is to study seismic structure and anisotropy of the lithosphere-asthenosphere system based on broadband seismograms of local, regional and teleseismic events. The obtained data will be analysed using several interpretation methods. The poster presents the results of analysis by shear wave splitting method.

The analysis was done based on SKS and SKKS phases recorded during a ~2 years observation period. For analysis, three single-station methods were used: cross-correlation, eigenvalue minimization and transverse energy minimization. The dependence of resulting splitting parameters on the backazimuth of the event was also analysed. The results show that time delays between slow and fast S-wave components are typically in the range of ~0.5-1.6 sec, with average 1.2 sec. The splitting is interpreted as a result of lattice-preferred orientation (LPO) of mantle olivine. The azimuths of fast velocity axis are mostly consistent and showed largely WNW-ESE direction. They correlate well with trends of tectonic units observed at the surface and with strike directions of major fault zones. This suggests vertically coherent deformation throughout the lithosphere and frozen-in LPO, reflecting last tectonic episode which shaped Sudetic area. Obtained results were also compared with previous seismic studies of the upper mantle anisotropy in the neighboring areas by various methods.
Opportunities & risks associated with global glacial meltwater changes and regional population growth from 1980 to 2100
Authors: Su Bo , Xiao Cunde , Chen Deliang
Published: March 2020

Mountain glacier is an indispensable supplier and modulator of freshwater to human’s sustenance in extensive cold and arid areas of the world. Melt waters from glaciers are widely used for ecosystem integrity, agricultural irrigation, hydropower operation, domestic and industrial activities. Under the background of global environmental changes such as global warming and regional population growth, linking climate-related glacio-hydrological changes to regional population growth is of the essence. However, a global assessment on opportunities/risks caused by glacial meltwater changes and population growth has not been presented until now. In this study, the population changes in glacier-fed area (GFA) for historical (1980-2015) and future (2010-2100) periods at the global, continental, national and basin scales were first mapped. Then, the opportunities/risks associated with population growth and glacier meltwater changes during 1980-2100 in 42 large-scale glacierized drainage basins with a minimum population of 10 thousand in 2015 were analyzed. Results reveal that the population living in the world’s GFA was 2030 million in 2015 and it was rapidly increased from 1278 million in 1980. The total population in GFA would continue to increase until a maximum is reached (e.g. peak population will appear around 2060 under the intermediate pathway for mitigation and adaptation, i.e. SSP2), beyond which the population would gradually decline. The opportunities/risks vary across basins and decades. Both of them are greatest in the Indus River basin, where the increase in glacial meltwater can seasonally satisfy the basic needs of additional 87 million people from the 2000s to 2040s, but about 200 million would be exposed to severe water scarcity due to the decrease in glacial meltwater and the population increase after the 2040s. 
Effects of hydrology, riparian topography, and land uses on the water quality in the middle and down streams Han River, China
Authors: Kuo Yi-Ming , Zhao Enmin
Published: March 2020

Influence of lands use patterns on water quality is complex and scale dependent. The relationship among land use patterns/configurations, topography, and surface roughness of riparian zones and river water quality in the middle and down streams Han River, China, was analyzed using geographically weighted (GWR) multiple regression models. The land use types within 50 m and 100 m of riparian zones that exhibit the strongest association with riverine water quality were investigated. Water quality samplings were collected from 94 sites during November in 2015 (dry season) and May in 2016 (wet season) under the rainy days. GWR models have better predictions of PO43- and TP in the Wet season and those of NO3-N, TN, and Chl-a in the Dry season. High prediction differences of PO43- and TP between Dry and Wet seasons. Most water quality variables in 50 m riparian zone have higher local parameter estimate (LPE) values than those in 100 m riparian zone, indicating 50 m riparian zone significantly influences riverine water quality. In the middle section, grass lands represent the source area of pollutants, which may discharge pollutants with runoff into Han River. However, forest land with high vegetation height can retard the rainfall becoming surface runoff and its relevant high surface roughness can increase infiltration and reduce the nutrient transport ability. Therefore, forest land exhibited a stronger contribution to water quality improvements. These findings provide important information for sustainable landscape management of riparian zones to improve riverine water quality.
Photosynthesis in a desert tree is driven by the highest light and temperature
Authors: Uni Daphna , Sheffer Efrat , Winters Gidon , Klein Tamir
Published: March 2020

Among living tree species, Acacia raddiana (Savi) and Acacia tortilis (Forssk), species of the legume family, populate some of the hottest and driest places on earth. Our research investigates the physiological processes underlying the unique survival of these trees in their extreme environmental conditions. We measured Acacia trees in their natural habitat once a month for two years to unravel the photosynthesis dynamics and water relations. Leaf gas exchange and leaf water potential were measured, as well as atmospheric and soil parameters. Daily and annual gas-exchange curves showed higher carbon assimilation during noon and in summer, when temperature and radiation were maximal (44°C, 2000 µmol m-2 s-1), and the air was dry (21% RH). Additionally, we found that the maximum rate of carbon assimilation was at PAR (photosynthetic active radiation) of 3000 µmol m-2 s-1. Our results suggest that water did not drive net carbon assimilation but rather light and temperature, which are already close to their maximum in our hyper-arid ecosystem.
Analysis of the differences between the North Pacific Victoria and meridional modes
Authors: Ji Kai , Zuo Hongchao , Li Jianping , Ding Ruiqiang
Published: March 2020

The Victoria mode (VM) and Pacific meridional mode (PMM) are the dominant SST modes over the North Pacific. Both are forced by a North Pacific Oscillation (NPO)-like extratropical atmospheric variability, and can act as a bridge (or conduit) through which North Pacific extratropical atmospheric variability influences ENSO. Consequently, the VM shares some resemblance with the PMM. However, the VM and PMM differ in terms of their spatial structure, temporal variations, and impacts on ENSO. In contrast to the local SST mode of the PMM in the subtropical northeast Pacific, the VM, as a basin-scale SST mode of the North Pacific basin, includes large-amplitude SSTAs over the northeast Pacific, the western North Pacific (WNP), and the high-latitude North Pacific. Results indicate that SLP anomalies associated with the VM are generally located west of those associated with the PMM. In addition, the VM has a unique temporal variability, independent of the PMM. Furthermore, the VM is more closely linked to ENSO than is the PMM, possibly because the VM combines the effects of the PMM and SSTAs in the WNP. Thus, the VM represents a more reliable precursor signal than the PMM for ENSO events and may have profound implications for ENSO prediction.