bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of grazing on photosynthetic carbon allocation in a temperate grassland
Authors: Zhao Yan , Tian Yuqiang
Published: March 2020

Grazing is an important human activity affecting grassland ecosystems. Many studies have shown that grazing changed the carbon (C) cycle of grasslands, but it is still not clear how grazing will affect the recent photosynthetic C allocation in the temperate grasslands. To clarify this question, a situ field 13C labeling experiment was carried out in the temperate grasslands of Inner Mongolia, North China, in 2015. In this study. Grazing included 3 intensities of no grazing, medium grazing and heavy grazing. Eighty-one days after the labeling, the plants allocated more recent assimilated 13C (6.52% of recovered 13C) to shoots under medium grazing than that of no grazing (5.60%) and heavy grazing (5.40%). The most 13C was allocated to the belowground (roots, soil and soil respiration) under no grazing (40.68%). However, within the belowground pools, 1.36% and 17.33% of 13C were stored in roots and soil under medium grazing which was twice than that under no grazing and heavy grazing, which could be explained by intermediate disturbance hypothesis. 13C labeling experiment demonstrated medium grazing increased C assimilates by two processes:(Ⅰ) the highest total C input into plants and soil and (Ⅱ)the least C loss by soil microbial respiration (3.20%) than no grazing grassland (5.19%) and heavy grazing grassland (3.47%). The turnover rate of soil assimilates under the no grazing (0.25 ± 0.07 day-1) was higher than that of grazing (medium grazing 0.059 ± 0.01 day-1; heavy grazing 0.064 ± 0.02 day-1). Overall, the no grazing isn’t the best for carbon accumulation and the medium grazing which promotes C input and C sequestration is the most suitable grazing intensity of temperate grassland in China.
The role of lakes in water cycling on the Tibetan Plateau under warming climate
Authors: Zhu Liping , Qiao Baojin , Yang Ruimin , Liu Chong , Wang Junbo , Ju Jianting
Published: March 2020

The Tibetan Plateau is one of the most important high elevation areas on the earth, performing sensitive response to global changes. As the Asia water tower, high mountain melting water is important water supplies for human development in TP and surrounded areas, but water phase transition is less known, especially under the climatic warming. Lakes are links of water phase transition and water cycle in TP. Lake water storage variations are sensitive to precipitation differentiations in the domination of the Westerlies and Indian monsoon. However, lake water storage performs inconsistent response in different regions & time periods. Based upon water balance observation, lake water storage variations are influenced by different factors, which also changed during different time period. Lake water temperature and thermoclines vary with seasons, and change water temperature gradient which influence water-air heat exchange. Lake salinities generally decreased since 1970s in the Serling Co region due to increasing of water storage. Based upon more than 60 lakes monitoring correction, it is found that lake transparency generally increased during 2000-2017 inferred by remote sensing interpretation. To aim at the deep recognizing of interactions between lake water variations and climatic changes, we need to know lake water storages and their variations for whole region and consecutive time series. To understand how heat exchanges between changing lakes and atmosphere, we need more consecutive observation data from large lakes. Therefore, the proposed work is to finish more lake survey and water balance monitoring, and continue to improve water cycling studies in the large lake basin scale for deep understanding how water cycles accompanied with mass and nutrients under the warming climatic conditions.
Detection of Spatiotemporal Changes of Water Vapor based on Large-scale BDS Reference Stations in China Area
Authors: Zhang Qinglan
Published: March 2020

China has built  national BDS reference stations (≥210 ) covering the entire territory and has been operating continuously for more than 3 years. In 2020, BDS  satellite navigation and positioning system will be fully built and provide global services, providing a good source of data for the use of ground-based BDS observations for water vapor detection and analysis. The author used national BDS reference stations observation data which covered China area  in 2019, combined with sounding observation data, to detect and analyze the temporal and spatial changes of water vapor , and given preliminary analysis results of the  water vapor detection performance and accuracy based on BDS observation . The results show that the detection results of atmospheric precipitation between BDS and sounding system are more consistent, which can reflect the change of atmospheric precipitation.  The system errors and standard deviations of the calculation results which based on  the BDS  observations and the sounding observations are relatively large, which may be related to orbit model and  the system stability of BDS needs to be improved.
Enhanced extended-range predictability of the 2018 late-winter Eurasian cold spell due to the stratosphere
Authors: Kautz Lisa-Ann , Polichtchouk Inna , Birner Thomas , Garny Hella , Pinto Joaquim
Published: March 2020

A severe cold spell with surface temperatures reaching 10 K below climatology hit Eurasia during late February/early March 2018. This cold spell was associated with a Scandinavian blocking pattern followed by an extreme negative North Atlantic Oscillation (NAO) phase. Here we explore the predictability of this cold spell/NAO event using ensemble forecasts from the Subseasonal-to-Seasonal (S2S) archive. We find that this event was predicted with the observed strength roughly 10 days in advance. However, the probability of occurrence of the cold spell was doubled up to 25 days in advance, when a sudden stratospheric warming (SSW) occurred. Our results indicate that the amplitude of the cold spell was increased by the regime shift to the negative NAO phase at the end of February, which was likely favored by the SSW. We quantify the contribution of the SSW to the enhanced extended-range forecast skill for this particular event by running forecast ensembles in which the evolution of the stratosphere is nudged to a) the observed evolution, and b) a time invariant state. In the experiment with the observed stratospheric evolution nudged, the probability of occurrence of a strong cold spell is enhanced to 45%, while it is at its climatological value of 5% when the stratosphere is nudged to a time invariant state. These results showing enhanced predictability of surface extremes following SSWs extend previous observational evidence, which is mostly based on composite analyses, to a single event. Our results support that it is the subsequent evolution throughout the lower stratosphere following the SSW, rather than the occurrence of the SSW itself, that is crucial in coupling to large-scale tropospheric flow patterns. However, we caution that probabilistic gain in predictability alone is insufficient to conclude about a causal link between the SSW and the cold spell event.

 
Modelling of interactions between bioturbation and mud distribution reveals effects on large-scale estuarine morphology
Authors: Brückner Muriel , Schwarz Christian , Kleinhans Maarten
Published: March 2020

Macrobenthic species that live within or on top of estuarine sediments can destabilize local mud deposits through their bioturbating activities. Resulting enhanced sediment availability will affect redistribution of fines and hence large-scale morphological change. To quantify this biological control on the morphological development of estuaries, we numerically model two contrasting bioturbating species present in NW-Europe by means of our novel literature-based eco-morphodynamic model. We find significant effects of both bioturbators on local mud accumulation and bed elevation change, leading to a large-scale reduction in deposited mud and gently sloped intertidal floodplains. In turn, the species-dependent reduction of mud content redefines their habitat and leads to constricted species abundances. Our results show that species-specific macrobenthic bioturbation determines large-scale morphological change through mud redistribution. This suggests that macrobenthic species have subtly changed estuarine morphology through space and time, depending on their distribution and composition.
Decadal variance of summer near-surface temperature maximum in Canada Basin of Arctic Ocean
Authors: Lin Long , He Hailun
Published: March 2020

In the summer Arctic, bump-like vertical temperature profiles of the upper layer in the Canada Basin suggest a near-surface temperature maximum (NSTM) beneath the mixed layer. This paper concentrates on describing the decadal variance of these NSTMs. Essentially, the temporal evolution of the summer NSTM revealed three decadal phases. The first period is before 2003, when the summer NSTM could rarely be observed except around the marginal of the Canada Basin. The second period is between 2003 and 2015, when the summer NSTM nearly occurred over the whole basin as accelerated decline of summer sea ice. The third period is from 2016 to 2017, when the summer NSTM almost disappeared due to prevailing warm surface water. Furthermore, for the background behind the decadal variance of summer NSTM, linear trends of the September minimum sea ice extent and surface water heat content in the Canada Basin from 2003 to 2017 were –2.75±1.08×104km2yr–1 and 2.29±1.36MJ m–2yr–1, respectively. According to a previous theory, if we assume that the trend of the summer surface water heat content was only contributed by NSTM, it would cause a decrease in sea ice thickness of approximately 13 cm. The analysis partially explains the reason for sea ice decline in recent years.
Improving Focal Mechanisms for Earthquakes in Taiwan Strait and Ryukyu Subduction Zone with Broadband Waveforms of Combined Networks
Authors: Lee Chieh-Chen , Tseng Tai-Lin , Jian Pei-Ru
Published: March 2020

  Taiwan region is a seismically active region formed by the oblique convergence between Philippine Sea Plate and Eurasia Plate. Focal mechanisms of most small-moderate sized earthquakes can be well constrained by the local seismic array, except for those occurred offshore Taiwan where azimuthal coverage is limited. To better understand the tectonic structures, it is desirable to improve the focal mechanisms using better located hypocenters, reasonable velocity models, and the best available stations. In this study we focus on the shallow earthquakes in Taiwan Strait and the intermediate-depth earthquakes in southernmost Ryukyu. Both regions are less explored but large historic events had been reported.

  For earthquakes in Taiwan Strait, we systematically studied earthquakes from 1996 to 2019, including the Mw5.7 Taiwan Shoal sequence happened on 2018/11/25. A total of 22 new moment tensors (MTs) were resolved in the passive margin by combining Fujian and Taiwan seismic networks from either side of the strait. For events closer to Fujian, China, the velocity model with Moho depth of 35 km yields overall lower compensated linear vector dipole (CLVD) and acceptable misfit values; while as a 40 km thick crust is better for events closer to or on the shore of Taiwan. This Moho variation under the Taiwan Strait, although subtle, agrees well with the velocity structure constrained independently by previous studies. Earthquakes in the middle of the strait are dominant in strike-slip and normal slip within 30 km depth. Shallow thrusting events are found only in the Miaoli offshore area of Taiwan. As for the 2018 Taiwan Shoal earthquake sequence, it is located right on the region absence of known fault-plane solutions, therefore offers important new constraints. All events of the sequence show high angle strike-slips and shallow centroid depth of 11-21 km, more consistent with seismicity determined by Fujian seismic center. This event is far away from the M8 1604 Quanzhou earthquake, and is also clearly unrelated to the structure of 1994 Mw 6.7 normal-faulting event in Tainan Basin. The 2018 sequence is probably the reactivation of a pre-existing normal fault that was created by rifting during the Cenozoic.

  For future work, we will re-evaluate the MTs of M>5.5 intermediate-depth earthquakes of the Ryukyu subduction zone by including waveforms of stations YNG and IGK from Japan network in the inversion. We will also test different upper mantle velocities in the model for the computation of Green’s functions. We anticipate that our work can provide a set of parameters more suitable for the MT inversion, and the MT results can delineate the Ryukyu subduction zone properties better.

 

keywords : Taiwan Strait, focal mechanisms, moment tensor inversion
Modeling of soil carbon dynamics, with focus on microbial activity
Authors: Ristorp Aas Elin , Koren Berntsen Terje , Eiler Alexander , Hellevang Helge
Published: March 2020

The representation of soil carbon dynamics is a major source of uncertainty in Earth System Models (ESMs). The terrestrial carbon pool is more than twice the size of the atmospheric pool. Therefore, the role of soil carbon as a source or a sink of atmospheric carbon, and in feedback loops is important to quantify in a changing climate. Decomposition processes of organic matter in soil have often been represented by first order decay equations, which make comparison and validation against observations difficult. Therefore, quantification of the uncertainties  and validation of improved parameterizations are problematic. An emerging approach to tackle these challenges is to represent microbial soil processes explicitly in the models. Following this approach, we have built a process based module that represent the carbon fluxes during soil decomposition, from aboveground litter to soil organic matter (SOM). The role of saprotrophs and mycorrhizal fungi is explicitly represented with separate carbon pools with associated fluxes. On a site level, we compare initial results from the stand alone module with both existing models and observations of carbon pools and fluxes. The observations are from the Norwegian Dovre Mountains, with data from three different alpine communities. These geographic areas are important, because they are subject to changes due to shrubification. In addition, these ecosystems can store large amounts of carbon. By modeling these sites, we gain more insight in the most important processes in soil decomposition, and how different microbial communities affect the carbon dynamics. We will further refine the module by expanding our study with more sites. The long-term objective is to develop an improved module that can be used to represent soil processes in ESMs, and thereby reduce the uncertainty connected to the exchange of carbon between land and atmosphere.
Time constraint on Danangou and Dongyaozitou mammalian faunas in the Nihewan Basin, North China
Authors: Liu Ping , Qin Huafeng , Li Shihu , Yuan Baoyin
Published: March 2020

Nihewan Basin is one of a series of well-developed East Asian Cenozoic basins, located in Hebei Province, North China. It has abundant gullies developed along both banks of the Sanggan River during and after the demise of Nihewan paleo-lake, creating a number of outcrops of the Nihewan Beds of fluvio-lacustrine origin, which are underlain by the Pliocene eolian Red Clay and overlain by the late Pleistocene loess. The fluvio-lacustrine sequence is rich sources of mammalian faunas and Paleolithic sites, thus providing unique insights into our understanding of land mammal biochronology and early human settlements in East Asia. Among the Nihewan Fauna (sensu lato), the Danangou (DNG) and Dongyaozitou (DZ) faunas are two of the important Pleistocene and Pliocene mammalian faunas in the Nihewan Basin. Except for a biostratigraphy, precise age control on the DNG and DZ faunas remains unavailable. Here we report a high-resolution magnetostratigraphic results that stringently constrain their ages. Rock magnetism and thermal demagnetization results show that magnetite and hematite dominate the remanence carriers in the DNG and DZ fluvio-lacustrine sequences. High-resolution magnetic polarity stratigraphy indicates that the DNG sequence recorded the Brunhes normal chron, the Matuyama reverse chron and the late Gauss normal chron, yielding the fossil-rich layers of DNG fauna with an age of ca. 1.95 Ma to 1.78 Ma during the Olduvai normal subchron. The DZ sequence was located at the late Gauss normal chron, leading an age of ca. 3.04−2.58 Ma before the termination of the Kaena reverse subchron. This result, together with previously published magnetochronology data obtained in the eastern basin, constructs a precise age constraints on the chronological framework of the Nihewan faunas and Paleolithic sites, especially during the Plio-Pleistocene transition.
Are Machine Learning methods robust enough for hydrological modeling under changing conditions?
Authors: Natel de Moura Carolina , Seibert Jan , Moro Mine Miriam Rita , Carvalho de Almeida Ricardo
Published: March 2020

The advancement of big data and increased computational power have contributed to an increased use of Machine Learning (ML) approaches in hydrological modelling. These approaches are powerful tools for modeling non-linear systems. However, the applicability of ML in non-stationary conditions needs to be studied further. As climate change will change hydrological patterns, testing ML approaches for non-stationary conditions is essential. Here, we used the Differential Split-Sample Test (DSST) to test the climate transposability of ML approaches (e.g., calibrating in a wet period and validating in a dry one, and vice-versa).  We applied five ML approaches using daily precipitation and temperature as input for the prediction of the daily discharge in six snow-dominated Swiss catchments. Lower and upper benchmarks were used to evaluate performances through a relative performance measure. The lower benchmark is the average of the bucket-type HBV model runs from 1000 random parameter sets. The upper benchmark is the automatically calibrated HBV model. In comparison with the stationary condition, the models performed slightly poorer in the non-stationary condition. The performance of simple ML approaches was poor for non-stationary conditions with an underestimation of peak flows, as well as a poor representation of the snow-melting period. On the other hand, a more complex ML approach (deep learning), the Long Short -Term Memory (LSTM), showed a good performance when compared with the lower and upper benchmarks. This might be explained by the fact that the so-called memory cell allowed to simulate the storage effects. 
The analysis of aerosol type and vertical distribution characteristics along Huaihe River based on CALIOP satellite measuring
Authors: yu Caixia
Published: March 2020

Based on CALIPSO level 2 aerosol profile data and surface meteorological observation data，aerosol extinction feature in haze was statistically analysed along Huaihe River. Using backward trajectory and cluster analysis method, pollution sources were investigated. Then vertical feature mask data(VFM) and ERA Interim data were used to analyse aerosol type, vertical distribution characteristics and typical weather patterns. The results showed that aerosol extinction coefficient along Huaihe River was largest near the ground with extinction coefficient 0.53 and decreased obviously along with high. Local pollution was primary source with contribution ratio of 46%. Furth more, pollution transmission from Yangtze River delta pollution zone and Beijing-tianjin-hebei was very important for the pollution event in Huai River basin. During stagnant synoptic situation, thermal inversion layer caused by warm advection at 850 hPa resulted in local air pollution, which was composed of continental aerosol. Weak upward motion in the surface layer transported pollutants to 0.4~0.8 km, where aerosol concentration was higher than that on the ground. When subtropical anticyclone 5880 isopiestic line location moves northward and westward, Yangtze River delta was controlled by high pressure through whole layer of the atmosphere, which lead to polluted dust aerosol accumulation. Due to downdraft, extinction effect was strongest near surface and decreased with height. In the early stage of cold air south down, cold north-west airstream caused by cold advection at 850 hPa brought Beijing-tianjin-hebei pollution to Huai River basin. Polluted continental aerosol and dust aerosol was main type of pollutants. The transport height of aerosols may be higher than 2 km with maximum transport being 1~2 km.
Magnetic flux transport in the photosphere of the Sun
Authors: Baranov Dmitrii , Vernova Elena , Tyasto Marta , Danilova Olga
Published: March 2020

On the basis of the synoptic maps of the photospheric magnetic field obtained by the National Solar Observatory Kitt Peak for 1978-2016, a latitude-time diagram of the magnetic field was built. When averaging intensity values over the heliolongitude, the magnetic field sign was taken into account. In order to consider the characteristics of the distribution of weak magnetic fields an upper limit of 5 G was set.

The latitude-time diagram clearly shows inclined bands corresponding to positive and negative polarity magnetic flows drifting towards the poles of the Sun. Two groups of flows are observed: 1. Relatively narrow bands, with alternating polarity, beginning near the equator and reaching almost the poles of the Sun. Along the time axis, the flow length of one polarity is on the order of 1-2 years; 2. short powerful flows, 3-4.5 years wide, propagating from the spot zone to the poles. These flows reach the poles simultaneously with the begin of the polar field reversal, apparently representing  the so-called “Rush to the Poles” phenomenon.

The pattern of magnetic field transport is significantly different for the northern and southern hemispheres. Alternating flows of positive and negative polarities most clearly appear in the southern hemisphere during periods of positive polarity of the southern polar field. For the northern hemisphere the picture is much less clear but for individual time intervals alternating flows of opposite polarities can be traced. The slopes of magnetic flux bands allow us to estimate the rate of meridional drift of magnetic fields, which was slightly different for the two hemispheres: V = (16±2) m/s for the southern hemisphere and V = (21±4) m/s for the northern hemisphere. The results obtained indicate that the distribution of weak magnetic fields over the surface of the Sun has a complex structure that is different for the two hemispheres and varies from cycle to cycle.
Object-based aviaton convection forecasts from global ensemble model
Authors: Warnan Adrien
Published: March 2020

In the framework of a single european sky and to improve Air Traffic Flow and Capacity

Management, involved actors need to share a common situational awareness of the airspace

conditions. These include the meteorological conditions with a focus on weather phenomena with a

strong impact on air traffic and network operations such as convection.

Within this framework, Météo-France is working to provide a new product of convection forecasts

based on ensemble prediction system (EPS) and global model, and is developing a similarity-based

method (Rottner et al., 2019) at Centre National de la Recherche Météorologique (CNRM).

The method aims to detect areas where meteorological conditions are homogeneous which are

called called objects. The latter are defined by a reference histogram representing the

meteorological phenomena to be detected and so are physically consistent. The similarity-based

method can be applied to each member of a EPS. The results can be summarized by a map that

contains the information predicted by all members of the ensemble. Thus, it provides spatialization

for local weather events. This method is currently tested to detect rainfall objects, however we can

apply this method to detect other event type, like convection. To discriminate the convection

characteristic within these rainfall objects, we use a diagnostic of cloud top pressure extracted from

global model outputs. Furthermore, to improve the convection forecast accuracy, the similarity-

based method can also be applied to several models to create a composite of convection forecast.

Météo-France will soon deliver a convection potential product to aeronautical users.
How do meteorological variables and topography control species-specific water uptake strategy along a forested hillslope?
Authors: Fabiani Ginevra , Penna Daniele , Klaus Julian
Published: March 2020

In the face of current global warming conditions, temperate forest ecosystems are expected to be strongly affected by temperature increase and more frequent and intense water shortage. This leads to severe stress for forest vegetation in many temperate systems. Therefore, understanding the vegetation water use in temperate forests is urgently needed for more effective forest management strategies. Root water uptake (RWU) is a species-specific trait (tree physiology and root architecture) and its spatio-temporal patterns are controlled by a range of site-specific (e.g., topography, geology, pedology) and meteorological factors (e.g., temperature, soil humidity, rainfall.

In the present study, we use stable water isotopologues as ecohydrological tracers combined with continuous measurement of hydrometeorological (weather variables, groundwater levels, soil moisture, streamflow) and physiological (sap flow, radial stem growth) parameters to investigate the spatio-temporal dynamics of water uptake for beech (Fagus sylvatica L.) and sessile oak (Quercus petraea (Matt.) Liebl) trees along a hillslope in a Luxemburgish catchment.

Fortnightly field campaigns were carried out during the growing season (April-October) 2019 to sample water from xylem, soil water at different depths, groundwater, stream water, and precipitation. Soil water isotopic composition and xylem water were extracted via cryogenic distillation. Grab sampling was performed for the other water pools. The isotopic composition was determined through laser spectroscopy and mass spectrometry (for xylem samples only).

From preliminary results, the isotopic composition of xylem water shows a marked seasonal variability suggesting a plasticity in RWU or a change in the isotopic composition of the water pools over the growing season. Moreover, beech and oak trees exhibit different uptake strategies when water supply is low. Within the range of observed groundwater variation topography does not play a statistically significant role on RWU.
A strategy to study the effect of rainfall and snow melting on gravity recordings from a superconducting gravimeter installed on Mt. Etna volcano, Italy
Authors: Koymans Mathijs , Cannavò Flavio , Carbone Daniele
Published: March 2020

We study the transient effect of groundwater mass changes on the observed gravity signal from a superconducting gravimeter deployed on Mt. Etna, Italy. Gravimeters are capable of detecting minor changes in the vertical component of gravity over time scales from minutes to years. Insight on geophysical phenomena that cause mass displacements in the subsurface can be obtained through the use of gravimetry. Gravity recordings integrate multiple components that contribute to the signal with different magnitudes. The effects of earth tides, atmospheric pressure changes, hydrological processes are among the above components. They need to be precisely evaluated, in order to isolate the signal caused by the volcanic processes. Here, we study the effect of groundwater mass changes on gravity, as a result of rainfall and snow melting, the latter estimated through GNSS interferometric reflectometry. A forward charge-discharge model is used to compare gravity recordings between 2018 - 2019 with observed precipitation events. We show that the observed gravity signal cannot be explained only through changes in groundwater mass, implying that other (volcanic) processes must have been at play.
Formation and persistence of extensional internally-drained basins: the case of the Fucino (Central Apennines of Italy)
Authors: Lanari Riccardo , Faccenna Claudio , Benedetti Lucilla , Bellier Olivier , Menichelli Irene , Primerano Paolo
Published: March 2020

The interaction between sedimentation/erosion and faulting represents one of the most intriguing topics in landscape and tectonics evolution. Recently, several studies attempted to unravel this issue but only few of them have been able to document the feedback between faulting and sedimentary loading. Here, we focus on how the sediment loading/unloading influences the dynamic of the faults system taking as study case the Fucino Basin in Central Apennines (Italy). The Fucino Basin represents a remarkable case study with respect to the other main extensional basins in the Apennines, because of its large dimension, rectangular shape, significant sediment thickness and more important, its endorheic nature throughout its evolution.

We present a detailed structural analysis all around the basin, investigating the kinematic and geometry of each main fault strand. The slickensides analysis reveals multiples families of slip-vectors and timing of activity which suggest a changing from N240° to N200° occurred during middle-Pleistocene. Moreover, using a simple isostatic model, we estimate that up to the 30% of the total geological displacement of the faults, which overall ranges from 0.5 to 3.5 km, is related to the sediments loading/unloading. Then, we demonstrate a positive feedback between sedimentation and faulting which may also lead to a re-organization in fault-kinematic related to a significant increasing in the vertical stress. Finally, we propose a conceptual model to support the permanent endorheic configuration of the Fucino basin, mainly related to a fault-slip increasing and kinematic changing due to the sediment loading.
Insights on the European Fault-Source Model (EFSM20) as input to the 2020 update of the European Seismic Hazard Model (ESHM20)
Authors: Basili Roberto , Danciu Laurentiu , Carafa Michele Matteo Cosimo , Kastelic Vanja , Maesano Francesco Emanuele , Tiberti Mara Monica , Vallone Roberto , Gracia Eulalia , Sesetyan Karin , Atanackov Jure , Sket-Motnikar Barbara , Zupančič Polona , Vanneste Kris , Vilanova Susana
Published: March 2020

The H2020 Project SERA (WP25-JRA3; http://www.sera-eu.org) is committed to updating and extending the 2013 European Seismic Hazard Model (ESHM13; Woessner et al., 2015, Bull. Earthquake Eng.) to form the basis of the next revision of the European seismic design code (CEN-EC8). Following the probabilistic framework established for ESHM13, the 2020 update (ESHM20) requires a continent-wide seismogenic model based on input from earthquake catalogs, tectonic information, and active faulting. The development of the European Fault-Source Model (EFSM20) fulfills the requirements related to active faulting.

EFSM20 has two main categories of seismogenic faults: crustal faults and subduction systems. Crustal faults are meant to provide the hazard model with seismicity rates in a variety of tectonic contexts, including onshore and offshore active plate margins and plate interiors. Subduction systems are meant to provide the hazard model with both slab interface and intraslab seismicity rates. The model covers an area that encompasses a buffer of 300 km around all target European countries (except for Overseas Countries and Territories, OTCs), and a maximum of 300 km depth for slabs.

The compilation of EFSM20 relies heavily on publicly available datasets and voluntarily contributed datasets spanning large regions, as well as solicited local contributions in specific areas of interest. The current status of the EFSM20 compilation includes 1,256 records of crustal faults for a total length of ~92,906 km and four subduction systems, namely the Gibraltar Arc, Calabrian Arc, Hellenic Arc, and Cyprus Arc.

In this contribution, we present the curation of the main datasets and their associated information, the criteria for the prioritization and harmonization across the region, and the main strategy for transferring the earthquake fault-source input to the hazard modelers.

The final version of EFSM20 will be made available through standard web services published in the EFEHR (http://www.efehr.org) and EPOS (https://www.seismofaults.eu) platforms adopting FAIR data principles.

The SERA project received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No.730900.
Sorption of trivalent actinides (Cm, Am) and their rare earth analogues (Lu, Y, Eu, Nd, La) onto orthoclase: Batch experiments, Time-Resolved Laser Fluorescence Spectroscopy (TRLFS) and Surface Complexation Modeling (SCM)
Authors: Brinkmann Hannes , Neumann Julia , Britz Susan , Brendler Vinzenz , Stumpf Thorsten , Schmidt Moritz
Published: March 2020

Sorption is one of the main processes, which determine the retention of radionuclides (RN) in a repository for nuclear waste. In a multi-barrier system, the host rock poses the ultimate barrier retarding the release of RN into the environment. Feldspars (e.g. orthoclase) are one of the main constituents of crystalline rock (e.g. granite), which is considered one potential host rock type in many countries (e.g. Finland, Sweden, Germany). In this study, the sorption of trivalent actinides (Cm, Am) and their rare earth analogues (Lu, Y, Eu, Nd, La) onto orthoclase (K‑feldspar) is investigated. For reliable predictions concerning the migration of RN, a process understanding on the molecular level of such processes is necessary. To achieve this, batch sorption experiments are combined with TRLFS and SCM.

Batch experiments were performed covering a broad range of experimental conditions (pH 4-11, oxic and anoxic conditions, [M3+] = 10-6-10-4 M, 3-50 gL-1 orthoclase (grain size: < 21 and 63-200 µm; SSA: 4.2 and 0.2 m2g-1)). Weak retardation below pH 5, followed by a strong increase between pH 5 and 7 and complete removal from solution at pH ≥ 8 was observed for all investigated metals. Cm- and Eu-TRLFS-measurements suggested the formation of an outer-sphere surface complex at lower (pH<5) and two different inner-sphere surface complexes at higher pH values (pH > 5 and pH > 7.5, respectively). Surface precipitation was observed for higher metal concentrations (10-4 M). As the investigated metals revealed a similar behavior over a broad range of conditions, a generic approach was used for the SCM to describe the system as a whole. Experimental data of different series with different metals were simultaneously fitted by coupling PHREEQC with UCODE using the same underlying speciation model. Resulting generic stability constants for the involved surface complexes will be presented.

The identification of comparable processes and their unified description with one suitable model is important to map the complexity of natural systems onto simplified geochemical models. This step is crucial for large-scale reactive transport calculations needed for a reliable safety assessment of potential repository sites, as they require enormous computing efforts.
Predicting the Bearing Capacity of Road Flexible Pavements using GPR
Authors: Ferrante Chiara , Bianchini Ciampoli Luca , Tosti Fabio , Alani Amir Morteza , Benedetto Andrea
Published: March 2020

Most of the damage in road-flexible pavements occur where stiffness of the asphalt and load-bearing layers is low. To this extent, an effective assessment of the strength and deformation properties of these layers can help to identify the most critical sections [1].

This work proposes an experimental-based model [2] for the assessment of the bearing capacity of road-flexible pavements using ground-penetrating radar (GPR – 2 GHz horn antenna) and the Curviameter [3] non-destructive testing (NDT) methods. It is known that the identification of early decay and loss of bearing capacity is a major challenge for effective maintenance of roads and the implementation of pavement management systems (PMSs). To this effect, a time-efficient methodology based on a quantitative modelling of road bearing capacity is developed in this study. The viability of using a GPR system in combination with the Curviameter NDT equipment is also proven.

The research is supported by the Italian Ministry of Education, University and Research under the National Project “Extended resilience analysis of transport networks (EXTRA TN): Towards a simultaneously space, aerial and ground sensed infrastructure for risks prevention”, PRIN 2017, Prot. 20179BP4SM

 

[1] Frangopol, D.M.; Liu, M. Maintenance and management of civil infrastructure based on condition, safety, optimization, and life-cycle cost. Infrastruct. Eng. 2007, 1, 29–41.

[2] Tosti, C. L. Bianchini, F. D'Amico, A. M. Alani and A. Benedetto, “An experimental-based model for the assessment of the mechanical properties of road pavements using ground-penetrating radar,” Construction and Building Materials, vol. 165, pp. 966-974, 2018.

[3] M. Simonin, J.L. Geffard, P. Hornych, Performance of deflection measurement equipment and data interpretation in France, International Symposium Non-Destructive Testing in Civil Engineering (NDT-CE) September 15–17, 2015, Berlin, Germany.
Local and remote causes of the equatorial Pacific cold sea surface temperature bias in the Kiel Climate Model
Authors: Zhang Yuming , Bayr Tobias , Latif Mojib , Song Zhaoyang , Park Wonsun , Reintges Annika
Published: March 2020

We investigate the origin of the equatorial Pacific cold sea surface temperature (SST) bias and its link to wind biases, local and remote, in the Kiel Climate Model (KCM) with dedicated coupled and stand-alone atmosphere model experiments. In the coupled experiments, the National Centers for Environmental Prediction Climate Forecast System Reanalysis (NCEP/CFSR) wind stress is prescribed over four different spatial domains: globally, over the equatorial Pacific (EP), the northern Pacific (NP) and southern Pacific (SP). The corresponding cold SST bias over the equatorial Pacific is reduced by 94%, 48%, 11% and 22%, respectively. Thus, the equatorial Pacific SST bias is mainly attributed to the wind bias over the EP region, with small but not negligible contributions from the SP and NP regions. Biases in the ocean dynamics cause the EP SST bias, while the atmospheric thermodynamics counteract it.

To examine the origin of wind biases, we force the atmospheric component of the KCM in stand-alone mode by observed SSTs and simulated SSTs from the coupled experiments with the KCM. The results show that wind biases over the EP, NP and SP regions are initially generated in the atmosphere model and further enhanced by the biased SST in the coupled model.

We conclude that the cold SST bias over the equatorial Pacific originates from biases in the ocean circulation that are forced by the biased surface winds over the EP, NP and SP regions. On the other hand, the cold equatorial Pacific SST bias amplifies the wind biases over the EP, NP and SP regions, which in turn enhances the cold SST bias by ocean-atmosphere coupling.
Study on the Influence of Heat Wave and Cold Wave Characteristics and Vulnerable Areas in Busan, Ulsan and Gyeongsangnam-do
Authors: Jo Miyeong , Ye Jiyeun , Yun Jihye , You Jaeeun , Kim Juyeong , Jang Jaedong , Noh Haemi
Published: March 2020

The frequency of extreme weather phenomena such as heat wave and cold wave has increased recently, and the intensity of weather has been strengthened, resulting in human and physical damage. The Republic of Korea has been working to reduce damage since 2018 by including heat and cold waves in natural disasters. The Korea Meteorological Administration (KMA) also provides impact-based forecasts, which requires research that suits local characteristics. In this study, weather observation data related to the summer heat wave in Busan, Ulsan and South Gyeongsang Province was analyzed to determine the weather conditions for the heat wave. In addition, in relation to the heat wave impact-based forecast that was provided regularly in 2019, the heat threshold was applied by comparing the current status of the heat-related patients with the maximum temperature, the number of consecutive days of the heat wave and the current status of the heat-related patients. The impacts of heat waves in different fields were analyzed, including livestock waste, fisheries food damage, and heat damage by crops. The cold wave also analyzed the number of days of cold wave in Busan, Ulsan, and South Gyeongsang Province by comparing the lowest temperature with the current status of cold-related patients. The impacts of cold weather conditions such as wind direction, wind speed and the number of consecutive days of the cold wave were also analyzed. Further, for regular provision of cold wave impact-based forecast to be implemented in 2020, the impacts of each cold wave vulnerable areas suitable for Busan, Ulsan, and South Gyeongsang Province were analyzed and referred to when applying cold wave thresholds.
Ecological water demand in the typical polder of Dongting Lake
Authors: Cai Yi , Tang Lihua , Tian Dazuo , Xu Xiaoyi
Published: March 2020

Dongting Lake is the largest lake in the middle reaches of the Yangtze River in China. After the completion of the Three Gorges Project, the relationship between the Yangtze River and Dongting Lake has a significant change with the decreased diversion ratio. Besides, due to the overexploitation of local human activities, some dry-up reaches appeared in the Dongting Lake region, especially in the polders with high strength  human activities. In order to scientifically understand the evolution law of water resources in those protective embankments in lakeside areas, and understand the relationship between human activities and ecosystem stability, the study works on the ecological water demand that coupled with the ecological capacity of the environment. As a typical polder, the Yule polder is selected as a case study in the Dongting Lake region. The objective is to obtain the ecological water demand process which can maintain the requirements of water quantity and quality of water to maintain water ecological needs under the condition of significant human impacts. Based on the actual situation of vegetation coverage, aquatic organism growth status and protection goals, and water demand of the industrial and agricultural population, taking the satisfaction degree of ecological water demand as an indicator, healthy of local water ecology is to be evaluated. Combining the hydrological situation of entire Yangtze River basin, the temporal distribution characteristics of ecological water demand in the Yule polder is analyzed, and also the feasibility of measures such as diverting Yangtze River water to alleviate the fragility of water ecology in the Dongting Lake region is discussed. These results could provide experience for solving similar problems in other regions.
Global dust climatology based on MODIS C6.1 and OMI-OMAERUV satellite data for the period 2005 to 2019
Authors: Gavrouzou Maria , Hatzianastassiou Nikos , Gkikas Antonis , Mihalopoulos Nikos
Published: March 2020

Aerosol particles influence the Earth’s radiation budget, and thus weather and climate, through their interaction primarily with solar, but also with terrestrial radiation. Moreover, aerosol-cloud interactions are essential, since aerosols act as Cloud Condensation Nuclei (CCN) and/or Ice Nuclei (IN), and thus crucially affect cloud properties. Dust is a major aerosol type, accounting for a great fraction of the global aerosol mass, mostly originating from the global deserts). Dust aerosols exert a strong radiative forcing, while acting as CCN and/or IN, thus modifying the cloud physical optical and radiative properties as well as also cloud lifetime and precipitation. However, the direct and indirect effects of dust are strongly dependent on their spatial and temporal distribution, which still has a considerable degree of uncertainty. This uncertainty is due to limitations of our knowledge about the dust spatiotemporal variability, which is due to the strong variability both of the dust sources and emissions as well as their transport and removal processes. However, in the last two decades, significant steps have been made towards improving the ability to observe dust from satellites. Advanced retrieval algorithms enable to effectively derive key aerosol optical properties which are characteristic of their physical properties such as size and absorptivity. The availability of such aerosol data since the early 2000s offers nowadays the possibility to build satellite-based dust climatologies.

In the present study a global dust climatology is constructed using a satellite based algorithm. The algorithm is initialized with the latest editions of Collection 6.1 MODIS-Aqua and OMAER-UV OMI-Aura data spanning the 14-year period from 2005 to 2018. The raw data of the algorithm are: (1) spectrally resolved MODIS Aerosol Optical Depth-AOD and (2) OMI Aerosol Index-AI), both available on a daily basis and at 1°x1° latitude-longitude spatial resolution. The algorithm computes, using the spectral AOD values, the aerosol Angstrom Exponent (AE), which is finally used along with AI as the main algorithm input data that are characteristic of aerosol size (AE) and absorptivity (AI). By applying appropriate thresholds that ensure the coarse size and significant absorptivity of dust, the algorithm identifies presence of dust in the atmospheric column on a daily and 1°x1° basis over the entire globe and the period 2005-2018. The algorithm estimates the frequency of presence and the associated loading (in terms of dust optical depth, DOD) of dust on a monthly and annual basis. The 14-year study period enables the computation of climatological mean values, as well as the intra-annual and inter-annual variability and trends of dust. Specific emphasis is given to the world’s great deserts, as well as to regions undergoing important transport of dust.
WAVERYS : A CMEMS global wave reanalysis during the altimetry period
Authors: Law Chune Stephane , Aouf Lotfi , Dalphinet Alice , Levier Bruno , Drillet Yann
Published: March 2020

As part of the Copernicus Marine Core service, WAVERYS is the multi-year wave reanalysis that aims to provide global wave data with a grid resolution of 1/5°. The wave reanalysis covers the period of 1993-2018 and provides 3-hourly classical integrated wave parameters describing the sea state at the ocean surface. The wave model used is the V4 version of the model MFWAM, which is driven by atmospheric forcing (winds and ice fraction) from ECMWF ERA5 reanalysis. This latter has showed a significant improvement regarding to the previous reanalysis ERA-Interim. WAVERYS includes the assimilation of altimeters wave data available during the period starting from Topex-Poseidon until Sentinel-3A missions. Directional wave spectra from Synthetic Aperture Radar (SAR) of Sentinel-1A and 1B missions are also assimilated. This is the first time that such directional wave spectra are used in a global wave reanalysis.

Further, WAVERYS uses a 3 hour surface current forcing provided by ocean reanalysis GLORYS12 implemented by Mercator-Ocean in the frame of Copernicus Marine Service with a grid resolution of 1/12°. The wave reanalysis is high skilled for ocean regions with dominant wave-currents interactions. Preliminary validation tests have shown improvement by 15% in scatter index for large scale high currents areas. This paper will give detailed characteristics of the wave system and will insist on the benefits of taking into account ocean currents and a physics calibrated for realistic swell propagation.

 