bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil moisture dynamics in winter under heavy snowfall conditions in Shonai (Japan)
Authors: Brandt Alexander , Zhang Qiqin , Lopez Caceres Maximo Larry , Murayama Hideki
Published: March 2020

Yamagata prefecture, facing the Japan Sea, is one of the heavy snow fall regions of the world. Around half of the annual precipitation of around 3000 mm falls in winter as snow, producing snow covers of more than three meters depth.  However, air temperature is around 0°C in winter and therefore relatively warm. Hence, snow density becomes 0.5 g/cm³ already early in the snow accumulation phase. To qualify and quantify interactions, three spots on a slope, forested with Japanese cedar (Cryptomeria japonica), have been selected to compare relationships on top, at the middle and at the bottom of snow covered slopes. The site represents the majority of mountain forests in north-eastern Japan. Monitoring soil and air temperature as well as precipitation and soil moisture we found strong interactions between the three hydrological regimes (precipitation, snow cover and soil) in winter. Soil did not freeze and hence volumetric soil moisture content changed during the winter season. Several sharp significant increases of soil moisture have been measured before the snow melt period even started. High rates of soil moisture increase together with an increase of Snow Water Equivalent (SWE) have been found to be caused by rain-on-snow events. In contrast, smaller rates of soil moisture increase in peaks were correlated with a decrease in SWE and therefore a snowmelt process. The interactions of snow cover and soil have been found to be different in the three different spots at the slope. Soil at the bottom of a slope reacts significantly to the highest number of events; soil on the slope reacts only to some events, but more intensively. Thus, most of the water is moving within the snowpack down the slope, increasing the SWE. Thereafter water reaches the soil surface and infiltrates it. This has been found to be also one reason for the formation of depth hoars and therefore the risk of avalanches.

To conclude, hydrological regimes in north-eastern Japan interact during the whole year due to winter air temperatures around 0°C and soil which does not freeze. The shape of peaks in soil moisture can be used to distinguish between rain and snowmelt causing the soil moisture increase. Various preferential flow patterns at different spots on a slope are an excellent basis for further studies and a basis for further monitoring and modelling.
Neglected idle rural residential land (IRRL): A challenge in achieving rural restructuring in metropolitan suburbs
Authors: Zhou Tao
Published: March 2020

Idle rural residential land (IRRL) is an important manifestation of changes in the human-land relationship during rural development. Studies on this topic are an important field in the study of sustainable land use, but quantitative analyses of IRRL in the academic community are still lacking. In this paper, we take the Pinggu, which has rapid urbanization, to analyse the spatial differentiation of IRRL and explore the spatial differentiation in the impact of different factors on IRRL. Results showed that IRRL was a common phenomenon in metropolitan suburbs with rapid urbanization. It had a spatial pattern of "one belt, three cores" in Pinggu, and its scale decreased from southeast to northwest. Industrial areas, semi-mountain ecotourism areas and urban fringe areas were the high-incidence areas of IRRL, while the idle rate of rural residential land in mountainous areas and plain agricultural areas was relatively low. The IRRL was the result of a combination of different factors, and there were differences among the different factors and regions. The transfer of rural labour, non-agriculturalization of industrial structure and mode of production and lifestyle caused by urbanization and industrialization were the major driving forces, and the lagging village planning and imperfect land use system increased the risk of IRRL. Our study contributes to filling the gap in quantitative research on IRRL to enrich the land use research system by exploring the interaction between humans and land in rural areas and thus has significance for rural restructuring and sustainable use of land in China.
Assessing future temperature and humidity trends using an ensemble of high-resolution simulations for the eastern Mediterranean region
Authors: Koutsogiannis Ioannis , Tzanis Chris G. , Philippopoulos Kostas , Alimissis Anastasios
Published: March 2020

Climate change is well-established as the major environmental issue of concern by the scientific community and the policy-makers around the globe. In order to examine climate variability both at a global and regional scale, key climatic variables such as temperature and humidity are examined in climate research. A significant temperature rise could lead to unsustainable conditions for the natural and human ecosystems. Additionally, water vapor is  recognized as the most important natural greenhouse gas, playing a principal role in the hydrological cycle. Specific and relative humidity are sensitive to temperature changes and therefore, examining temperature along with humidity variations is considered essential for the deeper understanding of the atmosphere’s thermodynamic and radiative processes. This study focuses on the analysis of future temperature, specific and relative humidity trends at different atmospheric pressure levels over the eastern Mediterranean region based on data from an ensemble of regional climate multi-model simulations for each of the Representative Concentration Pathways, namely RCP4.5, RCP8.5 and RCP2.6. The main purpose of this study is to examine whether statistically significant changes in the climate of the eastern Mediterranean are likely to occur in the future and investigate the relationship between temperature and humidity variations. The results of the monthly, seasonal and annual trend analysis are discussed.
High-precision compound-specific carbon isotopic analysis of underivatized amino acids using a multi-dimensional-HPLC and nano-EA/IRMS
Authors: Sun Yuchen , Ishikawa Naoto F. , Ogawa Nanako O. , Kawahata Hodaka , Takano Yoshinori , Ohkouchi Naohiko
Published: March 2020

We have developed an analytical method for the precise δ13C measurement of individual amino acid using a multi-dimensional high-performance liquid chromatography (HPLC) and a nano-scale elemental analyzer/isotope ratio mass spectrometry (EA/IRMS). Although this method is time-consuming, it can offer higher precision and accuracy than does the conventional analytical method such as GC/C/IRMS, because the derivatization of amino acids is not required. A reversed-phase column (CAPCELL PAK C18, Shiseido, Japan) and a mixed-mode column (Primesep A, SIELC Technologies, U.S.A.) were applied for the HPLC (Agilent Technologies, U.S.A.) with a charged aerosol detector (Thermo Fisher Scientific, U.S.A.) (Ishikawa et al., 2018). We conducted the isolation of underivatized amino acids in a standard mixture containing 15 proteinogenic amino acids (Gly, Ala, Glu, Arg, Val, Pro, Met, Tyr, Ile, Leu, Phe, Thr, His, Asp, Ser), and confirmed that all these amino acids were successfully isolated. Each collected amino acid was filtered through a 0.45 μm membrane filter (Pall, U.S.A.) and washed with diethyl ether to remove hydrophobic impurities. The δ13C values of these amino acids before and after the separation and purification were consistent, which proved that the whole experimental procedure did not change the δ13C values of amino acids. We applied this method to several aquatic organisms. The results show that the δ13C values of amino acids vary as large as 30‰ with Gly being most enriched in 13C.

Reference

Ishikawa et al., (2018) Anal. Chem., 90, 20, 12035-12041.

 
Submarine landforms on the Weddell Sea shelf imaged at high resolution using AUVs
Authors: Dowdeswell Julian , Batchelor Christine , Montelli Sasha , Ottesen Dag , Dowdeswell Evelyn , Evans Jeffrey
Published: March 2020

Multibeam echo-sounders were deployed from Autonomous Underwater Vehicles (AUVs) flying close to the seafloor of the Weddell Sea shelf in order to investiagte the glacial landforms there with a view to understanding processes and patterns associated with deglaciation from the Last Glacial Maximum on the eastern side of the Antarctic Peninsula. A horizontal resolution of 0.5 m (using conventional mulitbeam systems), and in some cases 0.05 m (using interferometric multibeam equipment), allowed delicate seafloor landforms to be mapped in several areas of the shelf beyond the Larsen C and former Larsen A and B ice shelves. A number of glacial landform assemblages were observed, including suites of delicate ridges associated with grounding-zone wedges and the grounding of icebergs on the shelf. These landforms are probably related to the action of tides moving the ice up and down through a series of tidal cycles. At the highest spatial resolution, individual dropstones derived from rain-out during the melting of floating ice were imaged clearly. Imaging the seafloor at such high resolution allows both very detailed descriptions of submarine landform morphology and also the complexity of such landforms and landform assemblages to be better understood, aiding the interpretation of the glacial and related processes that led to their formation.
Effectiveness of Vegetative Filter Strips for Mitigation in Higher-Tier Pesticide Exposure Assessments: Mechanistic Analysis with VFSMOD
Authors: Muñoz-Carpena Rafael , Fox Garey , Ritter Amy
Published: March 2020

Pesticides high-tier, long-term environmental risk assessments (ERA) are based on the combination of complicated mechanistic models to evaluate regulatory compliance. The modeling framework often involves large sets of input factors (model parameters, initial and boundary conditions, and other model structure options). How can we identify the relative importance of human, chemical, physical and biological drivers on the assessment results? Is there a case for “the right answers for the right reasons”? For the case of pesticide mitigation practices like vegetative filter strips (VFS) for runoff mitigation, what are the important factors controlling or limiting their efficiency under different field settings? We evaluate the combination of the current ERA frameworks (US EPA PWC and EU FOCUS SWAN) in combination with VFSMOD, an established and commonly used numerical model for the analysis of runoff, sediment, and pesticide transport in VFS. We present a systematic study of the importance of different field conditions that have been proposed in the past as limiting the efficiency of VFS in realistic settings: flow concentration (channelization) through the filter, timing of pesticide application compared to other drivers, assumptions about the degradation and remobilization of pesticide trapped in the filter between runoff events, seasonal presence of a shallow water table near the receiving water body. We identify instances in which the importance commonly assigned to these factors is not supported by the mechanistic analysis, where other factors different than those proposed largely control the results of the assessments.
Chemical speciation in GPU for the parallel resolution of reactive transport problems.
Authors: Gamazo Pablo , Bessone Lucas , Ramos Julián , Alvareda Elena , Ezzatti Pablo
Published: March 2020

Reactive Transport modelling (RTM) involves the resolution of the partial differential equation that governs the transport of multiple chemical components, and several algebraic equations that account for chemical interactions. Since RTM can be very computational demanding, especially when considering long term and/or large scale scenarios, several effort have been made on the last decade in order to parallelize it. Most works have focused on implementing domain decomposition technics for distributed memory architectures, and also some effort have been made for shared memory architectures. Despite the recent advances on GPU only few works explore this architecture for RTM, and they mainly focused on the implementation of parallel sparse matrix solvers for the component transport. Solving the component transport consumes an important amount of time during simulation, but another time consuming part of RTM is the chemical speciation, a process that has to be performed multiple times during the resolution of each time step over all nodes (or discrete elements of the mesh). Since speciation involves local calculations, it is a priory a very attractive process to parallelize. But, to the author’s knowledge, no work on literature explores chemical speciation parallelization on GPU. One of the reasons behind this might be the fact that the unknowns and the number of chemical equations that act over each node might be different and can dynamically change in time. This can be a drawback for the single instruction multiple data paradigm since it might lead to the resolution of several systems with potentially different sizes all over the domain. In this work we use a general formulation that allows to solve efficiently chemical specialization on GPU. This formulation allows to consider different primary species for each node of the mesh and allows the precipitation of new mineral species and their complete dissolution keeping constant the number of components.
Updating of existing vulnerability curves with data from recent events in the European Alps
Authors: Dosser Lea , Papathoma-Köhle Maria , Borga Marco , Fuchs Sven
Published: March 2020

Because effects of climate change and an increase in elements at risk in many mountain areas, loss increased throughout Europe. Yet, factors influencing loss, i.e. physical vulnerability of elements at risk, have gained less attention to date. Here, vulnerability is defined as the degree of loss resulting from the hazard impact on the building envelope. Recent studies have focused on evaluating vulnerability to dynamic flooding using proxies from case studies and based on empirical ex-post approaches (Papathoma-Köhle et al., 2011; Papathoma-Köhle et al., 2017; Fuchs et al., 2019a). However, the transferability of resulting vulnerability functions or curves to other case studies and, therefore, the ability of such models to actually predict future losses, is limited.

Existing vulnerability curves for the expression of the physical vulnerability of buildings to dynamic flooding in the alpine space are associated with a large number of uncertainties. The updating of the existing curves with data from recent events is necessary in order to make existing curves more reliable. In the present study damage data from three torrential events in Italy (Campolongo, Province of Trento, 2010; Braies, Province of Bolzano, 2017; Rotian river creek, Province of Trento, 2018) are used to update existing curves that have been developed for similar settlement types and similar hazard events in the Austrian Alps. At first a new vulnerability curve is developed only for the new study sites and is being compared with existing vulnerability curves in the Austrian Alps. As a second step the new data are fed to the existing vulnerability models (Fuchs et al., 2019b) in order to update them. Preliminary results are presented.

 

References

Fuchs, S., Keiler, M., Ortlepp, R., Schinke, R., and Papathoma-Köhle, M.: Recent advances in vulnerability assessment for the built environment exposed to torrential hazards: challenges and the way forward, Journal of Hydrology, 575, 587-595, https://doi.org/10.1016/j.jhydrol.2019.05.067, 2019a.

Fuchs, S., Heiser, M., Schlögl, M., Zischg, A., Papathoma-Köhle, M., and Keiler, M.: Short communication: A model to predict flood loss in mountain areas, Environmental Modelling and Software, 117, 176-180, https://doi.org/10.1016/j.envsoft.2019.03.026, 2019b.

Papathoma-Köhle, M., Kappes, M., Keiler, M., and Glade, T.: Physical vulnerability assessment for alpine hazards: state of the art and future needs, Natural Hazards, 58, 645-680, https://doi.org/10.1007/s11069-010-9632-4, 2011.

Papathoma-Köhle, M., Gems, B., Sturm, M., and Fuchs, S.: Matrices, curves and indicators: a review of approaches to assess physical vulnerability to debris flows, Earth-Science Reviews, 171, 272-288, https://doi.org/10.1016/j.earscirev.2017.06.007, 2017.
Detecting regime transitions in time series using dynamic mode decomposition
Authors: Gottwald Georg , Gugole Federica
Published: March 2020

We employ the framework of the Koopman operator and dynamic mode decomposition to devise a computationally cheap and easily implementable method to detect transient dynamics and regime changes in time series. We argue that typically transient dynamics experiences the full state space dimension with subsequent fast relaxation towards the attractor. In equilibrium, on the other hand, the dynamics evolves on a slower time scale on a lower dimensional attractor. The reconstruction error of a dynamic mode decomposition is used to monitor the inability of the time series to resolve the fast relaxation towards the attractor as well as the effective dimension of the dynamics. We illustrate our method by detecting transient dynamics in the Kuramoto-Sivashinsky equation. We further apply our method to atmospheric reanalysis data; our diagnostics detects the transition from a predominantly negative North Atlantic Oscillation (NAO) to a predominantly positive NAO around 1970, as well as the recently found regime change in the Southern Hemisphere atmospheric circulation around 1970.
Root and Shoot Responses to Salt Stress in Jojoba (Simmondsia chinensis)
Authors: Ephrath Jhonathan , Ben-Gal Alon , Bustan Amnon , Zhao Lina
Published: March 2020

Salinity affects plant growth due to both osmotic and ionic stress. The root system is essential in defense mechanisms against salinity, particularly involving salt ion avoidance or exclusion. Jojoba (Simmondsia chinensis) displays significant resistance to salinity. In the present study, Jojoba was planted in 60-L plastic buckets containing perlite growth medium and were provided with eight distinct salinity levels using two operating tanks of final irrigation solutions. Response of Jojoba to salinity was measured in above ground parameters and in roots using minirhizotron access tubes and imaging analysis. Leaf phosphorous and potassium concentrations decreased with increasing salinity level while leaf manganese, calcium, sodium and chloride concentrations increased with irrigation salinity level. Jojoba plants were found to have high level of storage of salt minerals in leaves but without effects on photosynthesis or transpiration. Roots exhibited different distribution patterns under different salinity treatments. Root length density increased with increased salinity at each depth. Root number and root length increased over time. During spring, the plant growth was faster than winter. Root diameter decreased over time due to new root development. Time had a more significant effect on root length density than irrigation water salinity or soil depth. Root number and root length were not significantly affected by the salt treatments.
Pedotransfer function to predict soil bulk density in Mediterranean agro-ecosystems, a systematic map.
Authors: Acutis Marco ,   SDAE 2019 team
Published: March 2020

To collate all the prior information about modelling the soil bulk density (BD) in Mediterranean climate agro-ecosystems at a world-scale, a systematic map was carried out. The strength of the systematic map approach is the collection of all the international peer review publications available in different archives that allows for the historical track of the topic developments.

To estimate BD, the most common approach is the use of Pedotransfer functions (PTFs). In this study, a search query was developed to find out all the already published PTFs for BD estimation and the search was carried out on the two most used citation database of peer-reviewed literature, namely SCOPUS and Web of Science (WoS).

The Bibliometrix package developed by Aria and Cuccurullo (2017) was used to map the main bibliometric information, extracted from Scopus and WoS. Following the systematic map procedure, we carried out a search on title, abstract and keywords using the following query: (bulk  AND density  AND  pedotransfer)  OR  (bulk  AND density  AND Mediterranean)) that yielded 750 results in Scopus and 889 in WoS.

Alternatively, ((bulk density  AND  pedotransfer)  OR  (bulk density AND Mediterranean)  AND NOT  (forest  OR  amazon*  OR  petrol*))  AND  (LIMIT-TO (DOCTYPE , article)  OR LIMIT-TO (DOCTYPE, review)), which have yielded 717 and 567 records in WoS and Scopus respectively, of which the 30% were found in both database.

The researches were published between 1989 and 2020. The final database consists of 889 articles coming from 243 different journals. The average annual publication growth rate was 4%, but in 2019 it was the 10%. United States was the most productive country with more than 90 articles published, as it was confirmed by the number of publications found in Geoderma and the American Soil Science journal with 20 and 15 % respectively. We found that less than 5% of the records were relevant to our target objective.

This search provided a background in terms of variables used to build the PFT, methodologies used (e.g. multiple linear, nonlinear regression, machine learning), and detailed land use. Given the importance of SOC stock for carbon sequestration and soil fertility, a PTFs is a valid tool to estimate the BD and therefore the amount of SOC in Mediterranean agro-ecosystems.
Refining geodiversity variables for monitoring global mining
Authors: Seijmonsbergen Harry , McMeekin Joe , Rentier Eline , Polman Emma , Rijsdijk Kenneth
Published: March 2020

Within a few hundred years, mining has changed from a traditional, low impact, local and regional extraction activity to a global industry that is responsible for the conversion of most natural landscapes into man-made (agri)cultural/urban landscapes. The irreversible extraction of specific geological and geomorphological resources has immensely impacted global scale geodiversity and ecosystem functioning. Although geodiversity is vitally important for global sustainability, this is not reflected in international policy, conservation and management, possibly due to a lack of harmonized, transparent and easy to measure science-based geodiversity indicators. We use two case studies on sand and phosphate mining to identify their drivers, pressures, state and impact on the environment to demonstrate how geodiversity variables can be used to raise awareness and to respond adequately. Sand provides society with important benefits, specifically through the provisioning of raw materials for use in construction, although extraction volumes are largely unknown. Phosphate has essential value for global food security as modern agriculture heavily depends upon phosphate fertilizers, but concerns have been raised suggesting potential depletion of rock phosphate in the near future. Sand and phosphate mining are in high demand, have associated scarcity concerns, are unevenly distributed on a global scale, and their extraction has numerous (unexpected) environmental and societal impacts. These examples demonstrate the need for monitoring and management of mining activities on global scales, in order to adequately respond to the effects of extraction of these resources. We provide refinements to the existing geodiversity variables related to geology and geomorphology and present opportunities to monitor their global geodiversity dynamics using remote sensing technology. Such data can support the improvement of global datasets on mining, and provide a pathway towards international recognition of geodiversity variables.
Global and local high-resolution magnetic field inversion using spherical harmonic models of individual sources
Authors: Baykiev Eldar , Ebbing Jörg
Published: March 2020

Inverting satellite and airborne magnetic data with a common model is challenging due to the spectral gap between the data sets, but needed to provide meaningful models of lithospheric magnetisation.

Here, we present a step-wise approach, where first spherical prisms (tesseroids) are used for global magnetic inversion of satellite-acquired lithospheric field models and second airborne data re inverted in their suitable spectral range for added details. For the synthetic test, the susceptibility model of Hemant (2003) was used as a starting point to calculate the spherical harmonic model of each tesseroid in the model. The resulting spherical harmonic coefficients were inverted for magnetic susceptibility in the global model, where the geometry is based on seismic or gravity observations. The projected gradient method is used to avoid negative susceptibilities in the result. After the global inversion, high-resolution local tile-wise inversion together with synthetic airborne data within a different wavelength range is performed for even higher resolution results.

The approach is applied to the Swarm-derived LCS-1 field model and for selected areas with high-resolution aeromagnetic coverage.
The impacts of large bluff roughness elements on turbulent transport of momentum and scalar in the urban boundary layer
Authors: Li Qi
Published: March 2020

More than half of the world population lives in cities. It is imperative to improve our predictive understanding of the urban boundary layer. In particular, considerable knowledge gaps still exist in turbulent transport of scalars (temperature, moisture and air pollutants) over urban rough surfaces, especially in the urban roughness sublayers. Using obstacle-resolving large eddy simulations, we first compare and contrast momentum and passive scalar transport over large, three-dimensional roughness elements. Dispersive scalar fluxes are shown to be a significant fraction of the total fluxes within the roughness sublayers. Strong dissimilarity is also noted between the dispersive momentum and scalar fluxes. The results highlight the need for distinct parameterizations of the turbulent and dispersive fluxes, as well as the importance of considering the contrasts between momentum and scalar transport for flows over very rough surfaces. In addition, the links between momentum and scalar roughness lengths (z0m and z0s) are explored by developing a conceptual framework that considers z0m and z0s at two distinct scales, namely micro and macro scales. Using a surface renewal theory for macro-scale roughness lengths, a log(z0m/zos) scaling with Re*1/2 is predicted and is supported by LES results. Overall, these results underline the potential of using wall-modeled, large-obstacle resolving LES to improve our process-based understanding, as well as to identify and represent the missing first-order physical processes in the ABL.   
Aminomethylphosphonic acid (AMPA) retention in different soil profile horizons
Authors: Gonzalo Mayoral Eliana , Aparicio Virginia , Costa José Luis , De Gerónimo Eduardo
Published: March 2020

Aminomethylphosphonic acid (AMPA) is a metabolite of microbial degradation of the widely used herbicide glyphosate and other phosphonate compounds, such as detergents. In the soil, AMPA has a strong adsorption than the glyphosate. No studies have been reported on adsorption of AMPA in the soil profile. There are only a few studies of retention in superficial horizons of the soil. In this sense, the objective of this study is to determine the adsorption coefficients of AMPA in the three main horizons of a typical Argiudoll.

The adsorption isotherms were performed by shaking 1 g of soil in 10 ml of CaCl2 (0,01M) at different concentrations of AMPA (0, 2, 5, 10, 20, 50, 100 ppm). Six replications were performed for each main horizon (A-B-C). The samples were incubated and agitated at 25 °C for 24 hours to reach equilibrium. Then it was centrifuged at 3000 rpm for 10 minutes. The concentration of AMPA was quantified in UPLC MS/MS (Waters®). The experimental data was adjusted following the Freundlich model. At the same time, physical-chemical determinations of each horizon were made in order to characterize the soil.

The percentage of AMPA adsorption was greater than 91, 85 and 74% of the concentration applied, for all concentration, in horizons A, B and C, respectively. These percentages decreased for each horizon from lower to higher concentration. If the adsorption between horizons is compared for each applied concentration, horizon B is the one that presents the highest percentages of adsorption of AMPA, followed by A, and then C. Only in the highest concentration used (100 ppm), horizon A registers the highest percentage of adsorption with respect to the other horizons. In this sense, the Kf values obtained were 295, 329 and 152 for the horizons B, A and C, respectively, with significant differences for the latter.

When looking for correlations between Kf values and the soil properties, it was found that the cation exchange capacity, K content and percentage of clays are the properties that correlate most strongly with the Kf value. On the other hand, the percentage of sand and the pH showed a strong negative correlation with Kf.

The results obtained indicate that, in soils (or horizons) with a high clay content, the AMPA is strongly retained, decreasing the probability of being transported to the underground water.
Abnormal groundwater flow system between two rivers: a numerical investigation
Authors: Ruoyi Li , Xu-Sheng Wang , Peng-Fei Han
Published: March 2020

Groundwater flow system has long been recognized as the local, intermediate and regional flow systems since Toth (1963). For groundwater flow in an unconfined aquifer between two parallel rivers (or ditches), as indicated by Hubbert (1940), there are two local flow systems contributing groundwater discharge to the two rivers from infiltration recharge. Surprisingly, this model has never been examined until Han et al. (2019) pointed out that something may be wrong: not only two flow systems exist. The problem was further investigated with a two-dimensional numerical model on MODFLOW for saturated groundwater flow below the arch-shape water table receiving a uniform infiltration recharge. Streamlines were obtained with MODPATH to identify the flow systems. We discovered that an abnormal groundwater flow system could emerge beneath the two local flow systems under some conditions, which forms a pass through flow from the high river to the low river. This pass-through flow system exists when the water level difference between the two rivers is sufficiently large and the infiltration recharge is sufficiently low. As a result, the base flow of the low river may be not only attributed to the captured infiltration recharge from the nearby local flow system but also partly originated from the high river. The ratio of the contribution from the pass-through flow system to the total groundwater discharge toward the low river could be higher than 20% and almost linearly increases with the water level difference between two rivers. More details of such an abnormal groundwater flow system were investigated as well.  
The end of the anthropogenic aerosol era?
Authors: Bauer Susanne E. , Tsigaridis Kostas
Published: March 2020

The Earth’s climate is rapidly changing. Over the past century, aerosols, via their ability to absorb or scatter solar radiation and alter clouds, played an important role in counterbalancing some of the greenhouse gas (GHG) caused global warming. This, over a century-long anthropogenic aerosol cooling effect, prevented present day climate to have yet reached even higher surface air temperatures and subsequent more dramatic climate change impacts. Trends in aerosol concentrations and optical depth show that in many formerly highly polluted regions such as Europe and the United States of America aerosol precursor emissions have already decreased back to pollution levels of the 1950s. More recent polluting countries such as China may have reached a turning point in recent years as well, while India keeps still following an upward trend. Here we study aerosol trends in the CMIP6 simulations of the GISS ModelE climate model using a fully coupled atmosphere composition configuration, including interactive gas phase chemistry, and either an aerosol microphysical (MATRIX) or a mass based (OMA) aerosol module. Results show that the question if we are already at a period where aerosol radiative forcing continuously declines globally depends on the aerosol scheme used. Using the aerosol microphysical scheme, where the aerosol system reacts stronger to the trend in sulfur dioxide (SO2) emissions, global peak direct aerosol forcing was reached in the 1980’s, whereas the mass-based scheme simulates peak direct aerosol forcing around 2010. The models are tested again ice core records, satellite and surface network datasets. An evaluation with satellite data between 2001 and 2014 demonstrates that the model that better reproduces the satellite retrieved trends has reached maximal aerosol direct forcing in the 1980s, and is since on a decreasing global forcing trajectory. As a consequence, we expect that the recently observed global warming which is primarily driven by greenhouse gases has been augmented by the effect of a decreasing aerosol cooling effect on the global scale.
Gravity waves as a mechanism of coupling oceanic and atmospheric acoustic waveguides to seismic sources
Authors: Godin Oleg
Published: March 2020

Direct excitation of acoustic normal modes in horizontally stratified oceanic waveguides is negligible even for shallow earthquakes because of the disparity between velocities of seismic waves and the sound speed in the water column. T-phases, which propagate at the speed of sound in water, are often reported to originate in the open ocean in the vicinity of the epicenter of an underwater earthquake, even in the absence of prominent bathymetric features or significant seafloor roughness. This paper aims to evaluate the contribution of scattering by hydrodynamic waves into generation of abyssal T-waves. Ocean is modeled as a range-independent waveguide with superimposed volume inhomogeneities due to internal gravity waves and surface roughness due to wind waves and sea swell. Guided acoustic waves are excited by volume and surface scattering of ballistic body waves. The surface scattering mechanism is shown to explain key observational features of abyssal T-waves, including their ubiquity, low-frequency cutoff, presence on seafloor sensors, and weak dependence on the earthquake focus depth. On the other hand, volume scattering due to internal gravity waves proves to be ineffective in coupling the seismic sources to T-waves. The theory is extended to explore a possible role that scattering by gravity waves may play in excitation of infrasonic normal modes of tropospheric and stratospheric waveguides by underwater earthquakes. Model predictions are compared to observations [L. G. Evers, D. Brown, K. D. Heaney, J. D. Assink, P. S. M. Smets, and M. Snellen (2014), Geophys. Res. Lett., 41, 1644–1650] of infrasonic signals generated by the 2004 Macquarie Ridge earthquake.
A framework for visualizing the convergence performance of global optimization algorithms for hydrological models
Authors: Lan Tian , Lin Kairong , Xu Chong-Yu , Chen Xiaohong
Published: March 2020

The convergence performance of global optimization algorithms determines the reliability of the optimized parameter set of hydrological models, thereby affecting the prediction accuracy. This study applies advanced data analysis and visualization techniques to design a novel framework for characterizing and visualizing the convergence behavior of the optimization algorithms when used for the parameter calibration of hydrological models. First, we utilize violin plots to assess the convergence levels and speeds in individual parameter spaces (ECP-VP). The density distributions of violin plots match the possible properties of fitness landscapes. Then, the parallel coordinates techniques are used to simulate the dynamic convergence behavior and assess the convergence performance in multi-parameter space (ECP-PC). Furthermore, the possible mechanism for the effect of linear or nonlinear relationships between the parameters on the convergence performance is investigated using the maximal information coefficient (MIC) and the Pearson correlation coefficient (Pearson r). Finally, the effect of the parameter sensitivity on the convergence performance is analyzed. The proposed framework is applied in multi-period and multi-basin dynamic conditions as case studies. The results showed that the ECP-VP and ECP-PC techniques were well suited for the evaluation of the convergence performance of global optimization algorithms for hydrological models. The evaluation results provided valuable information on determining the reliability of the final optima, as well as the dominant response modes of hydrological models. It is also demonstrated that the convergence levels and speeds in pairwise parameter spaces depend on the linear correlations but not on the nonlinear correlation between the parameters. Additionally, there is no significant relationship between the sensitivity of the parameters and their convergence performance.
Differential nitrogen isotope variation of tree-rings in two coniferous forests under climate change, Japan
Authors: Lopez Caceres Maximo Larry , Tanabe Satoru , Santini Filippo , Voltas Jordi , Seidel Felix , Yamanaka Toshiro
Published: March 2020

Tree-ring δ15N provide long-term reliable information of soil available nitrogen, especially under increasing atmospheric N deposition upon forested ecosystems. In this study tree-ring δ15N values of Larix kaempferi and Cryptomeria japonica were measured for five trees each from a heavy snowfall region in north-eastern Japan, respectively. Larch and cedar tree-ring δ15N showed a range of -1.2 to 3.8 ‰ and -1.6 to 1.6 ‰, respectively. Larch trees showed a stable increase in δ15N values, while cedar trees showed a steady decreasing trend for the period 1970-2017. However, the divergence in the two tree series started in the early 1990’s. Both tree stands are exposed to the same atmospheric N deposition, therefore in principle both should have been affected equally. Similarly, an increase or a decrease in the δ15N value of the soil available N cannot be the reason since tree-rings values showed contrasting trends, unless this difference exists in each forest stand, however this seems unlikely. Another possibility could be the canopy uptake of depleted N from the atmosphere in cedar as the N demand increases could be responsible for cedar tree-ring δ15N temporal decrease but it does not explain the increase observed in larch. We speculate that low N demand and the increase in root biomass as tree grows could have decreased 15N discrimination by the EM fungi. The most plausible explanation for the contrasting results is that fractionation by the mycorrhiza fungi (Ecto and Arbuscular, respectively) during N root uptake was lower in larch (3.2 ‰) than in cedar (4.7 ‰) trees, which was related to the lower N demand as tree-ring wood %N was in average 0.06 and 0.10, respectively.
Investigation on wellbore cement degradation under geologic CO2 storage conditions by micro-CT scanning and 3D image reconstruction
Authors: Zhang Liwei , Wang Yan , Gan Manguang , Liu Sinan , Li Xiaochun
Published: March 2020

This study presents a CT scanning and image analysis protocol to characterize wellbore cement degradation under geologic CO2 storage (GCS) conditions. The CT scanning and image analysis procedures described in the protocol are as follows: 1) CT scanning of the cement sample before exposure to CO2; 2) exposure of the cement sample to supercritical CO2 or CO2 saturated brine; 3) CT scanning of the cement sample after the exposure experiment; 4) application of 3D rigid registration to align all CT image frames, in order to eliminate pixel location variation between CT image frames due to sample drift; 5) acquisition of grayscale intensity difference images, which are obtained by subtraction of CT images after the CO2 exposure experiment from raw CT images before the CO2 exposure experiment; 6) application of noise filtering technique on grayscale intensity difference images to obtain images with good quality; 7) acquisition of 3D pore structure change of the cement sample after CO2 exposure experiment from grayscale intensity difference images, showing degradation of wellbore cement. To demonstrate the application of the protocol, an experiment of reaction between CO2 and wellbore cement under GCS conditions was conducted and the wellbore cement samples used in the experiment went through aforementioned CT scanning and image analysis procedures. CT image analysis results demonstrate a region with increased porosity in the exterior of the cement samples (Zone 1) and a region with decreased porosity next to Zone I due to CaCO3 precipitation (Zone 2). Next to Zone 2, a region with increased porosity due to Ca(OH)2 and C-S-H dissolution (Zone 3) was observed. In summary, this study proves feasibility to use 3-D CT scanning and CT image analysis techniques to investigate CO2-induced degradation of wellbore cement.
A quantitative study of moisture transport variation on the interdecadal variation of the summer precipitation in South China from 1979 to 2015
Authors: Hua Lijuan
Published: March 2020

The summer precipitation in South China (SC) has experienced a pronounced interdecadal variation during 1983–2013

with trend transition in the late 1990s. This study quantitatively investigates the precipitation variation and its connection to

water vapor transport by combining the Lagrangian trajectory-based Dynamic Recycling Model and the clustering method

of self-organizing map. The external moisture outside of SC explains most (84%) of the mean and the interdecadal variation

of the summer rainfall, mainly through the southwest transport pathways. A long-distance southwest pathway related to

cross-equatorial flow and eastward flow over the Northern Indian Ocean explains 31.5% of mean precipitation and 50.4% of

the upward precipitation trend before 1997. The other branch of the southwest pathways has relatively shorter length over

North Indian Ocean, South China Sea, and Southeast Asia, explaining 35.7% of the mean and 51.2% of the downward trend

after 1997. Also, for the downward trend, the westerly-driven moisture transport over Eurasia acts as the second contributor

(32.2%) to the precipitation decrease. However, the western-Pacific pathway explains the smallest portion (≤ 3%) of

the trends, suggesting weak influence from the subtropical high. The large-scale circulation anomaly in the form of zonal

and meridional wave trains control the interdecadal variability of the SC precipitation. It is found that the circumglobal teleconnection

and Pacific–Japan teleconnection significantly correlate to the two wave trains, whose match relation strongly

modulates the trend transition in the 1990s for the SC summer precipitation.
Enhanced flow rating using neural networks with water stage and electrical conductivity as predictors
Authors: Schmid Bernhard H.
Published: March 2020

Streamflow is of fundamental importance to hydrology and water resources management, but it is difficult and/or expensive to measure directly in a continuous manner. Consequently, continuous measurements mostly make use of stage recording, with the values of stage being converted into those of streamflow by means of rating curves (or a digital counterpart). Historically, a major practical advantage of a one input – one output stage-discharge relationship was its straightforward handling in the form of a diagram, but that is no longer relevant. Thus, there is little reason why streamflows should be inferred from stage only, provided an additional input variable proves useful and can easily (and inexpensively) be recorded continuously.

Electrical conductivity (EC) appears as a potentially powerful candidate to serve as a further input variable improving streamflow estimates, and artificial neural networks (ANNs) are well suited to handle more than one input. In alpine streams EC has been reported to be a viable alternative to water level as predictor variable in streamflow estimation (Weijs et al., 2013). The approach advocated here differs from that just cited by using EC in addition to, not in lieu of stage as predictor variable. That way, it is believed that the field of potential application should be wider. In the work reported here, stage and EC data were used to develop a multilayer perceptron type ANN (2-4-1) to estimate flow in a small Austrian stream (Mödling) with a catchment of fairly mixed composition (forested, agricultural and urbanized areas). While the alpine catchment studied by Weijs et al.(op. cit.) probably is at the upper end of EC usefulness in streamflow estimation, the Mödling catchment offers less favourable conditions, with EC being potentially subject to some influence of human activities. In spite of these modest (but not unusual) conditions, the research reported documents that EC improved streamflow estimates. An analysis of the data with the aid of a network interpretation diagram, Garson's algorithm (Garson, 1991) and a sensitivity analysis performed on the two input variables (stage and EC, resp.) shows EC to be a useful additional predictor, with its relative 'importance' amounting to roughly one third of that of stage in this catchment.

References

Garson, G.D.: Interpreting neural-network connection weights. Artif. Intell. Expert, 6, 47-51, 1991.

Weijs, S.V., Mutzner, R., Parlange, M.B.: Could electrical conductivity replace water level in rating curves for alpine streams? Water Resour. Res 49, 343-351, 2013.
Messy Maps: Qualitative GIS for Urban Flood Resilience
Authors: Taylor Faith , Millington James , Jacob Ezekiel , Malamud Bruce , Pelling Mark
Published: March 2020

We present a methodology to include qualitative aspects of flood resilience such as emotion, social connections and experience into urban planning using qualitative GIS. The geographic information system (GIS) has become ubiquitous in urban planning and disaster risk reduction, but often results in resilience being conceptualised and deployed in highly technocratic and quantitative ways. Yet in the urban Global South, where the rate of informal growth often outstrips our ability to collect spatial data, the knowledge infrastructures used for resilience planning leave little room for participation and consideration of local experience. This presentation outlines two interlinked projects (‘Why we Disagree about Resilience’ and the follow-on ‘Expressive Mapping of Resilient Futures’) experimenting with qualitative GIS methodologies to map resilience as defined by informal settlement residents. We show examples from two case study cities, Nairobi (Kenya) and Cape Town (South Africa), with applicability across the urban Global South. Four map layers were generated: (i) flood footprints showing the detailed spatial knowledge of floods generated by locals; (ii) georeferenced, narrated 360° StorySpheres capturing differing perspectives about a space; (iii) spatial social network maps showing residents connections to formal and informal actors before and during floods; (iv) multimedia pop-ups communicating contextual details missing from traditional GIS maps. We show that for informal settlements, many locations and aspects of resilience have vague or imprecise spatial locations, and that placing markers on a map makes them visible in ways that planners can begin to engage with. We discuss challenges such as privacy, legacy and participation. Although challenges remain, we found openness by city-level actors to use qualitative forms of evidence, and that the contextual detail aided their retention and understanding of resilience. The ‘messy’ maps we present here illustrate that in the era of big data and metrics, there is a space for qualitative understanding of resilience, and that existing knowledge and spatial data infrastructures have potential to be more inclusive and holistic.