bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutionary process of saline groundwater influenced by palaeo-seawater trapped in coastal deltas: A case study in Luanhe River Delta, China
Authors: Dang Xianzhang , Gao Maosheng , Wen Zhang , Hou Guohua
Published: March 2020

Coastal aquifers provide fresh drinking water to over 20% of the world’s population. In recent times, they have come under immense pressure due to salinization. This study aims to investigate the origin of groundwater salinity and elucidate the major processes controlling shallow groundwater (depth of 0~50m) evolution in the Luanhe River Delta since the Holocene. Rapid increase in Electric Conductivity (EC) profile was observed in the area, as such, based on the vertical distribution of EC and sedimentary history, shallow groundwater was generalized into two zones for analysis: the groundwater in Holocene stratum (HSG) and groundwater in Late Pleistocene stratum (PSG). The isotopic (δ18O, δ2H and 14C) analyses showed that the HSG is recharged by modern surface water, while the PSG having enriched isotopic values could have been recharged during a warmer Holocene transgression period. The hydrochemistry analyses demonstrated that seawater is the major source of salinity in groundwater and overtime a series of geochemical processes (mineral weathering and/or cation exchange) modified the chemistry of the groundwater. The combined use of Cl- and δ18O yielded four classes of groundwater (fresh water, brackish water, saline water and brine), while the mixing phenomena between fresh water and seawater was identified to be the main evolutionary process of the shallow groundwater. To improve understanding of evolution of multiple groundwater types in a spatial context, a conceptual model was developed integrating the results derived from the presented study in a vertical cross-section. The conceptual model shows that the residual seawater mixes with freshwater from surface recharge at the shallow aquifer of the delta plain where the lagoon environment provides salinity concentration conditions for the formation of hyper-saline water. Due to the precipitation and accumulation of the salinity from hyper-saline water, some brine might form formed in late Pleistocene continental stratum.
Wave groups and spectral shape in ice
Authors: Gemmrich Johannes , Thomson Jim , Mudge Todd
Published: March 2020

The reduction of arctic summer ice coverage has prompted a renewed interest in the physics of wave-ice interactions. Progress has been made on the observational, theoretical and modeling aspects of waves in the presence of ice.

This presentation will address our recent observational studies of spectral wave properties in the marginal ice zone, and in ice covered seas. Waves propagating through ice are attenuated and scattered, resulting in a pronounced change of the shape of the wave spectrum. In particular, the strong attenuation of the high frequency components affects wave steepness and the spectral bandwidth, and thus wave groupiness and the crest height distribution.

We present data for various ice conditions, obtained from drifting SWIFT buoys, a moored ADCP and moored inverted echosounders. All observations show well developed group structures of the waves. However, for different datasets we obtain opposite dependencies between wave groupiness and wave spectral characteristics. This suggests that depending on ice condition, both, the linear mechanism of wave superposition, or wave nonlinarites can be responsible for the wave group enhancement in ice. These mechanisms will be discussed.
Probabilistic Cover-Basement Interface Characterization in Cloncurry, Australia, using Magnetotelluric Soundings
Authors: Seillé Hoël , Visser Gerhard , Markov Jelena , Simpson Janelle
Published: March 2020

Cloncurry is located in the Mount Isa province in Queensland, NE Australia. The Mount Isa Province is a well-known metallogenic province in Australia which hosts many IOCG deposits. One of them is the Ernest Henry IOCG deposit, which was found below cover in the 90’s. The cover in this area comprises of regolith and the Jurassic-Cretaceous sediments of Eromanga and Carpentaria Basins. This deposit appears to belong to a complex mineral system which extend over the entire Cloncurry District.

A magnetotelluric (MT) survey was conducted in 2016 by Geoscience Australia and The Geological Survey of Queensland in the vicinity of the Ernest Henry IOCG deposit, in order to characterize the electrical properties of the mineral system beneath it. The derived 3D electrical conductivity model highlights the variable cover thickness over the area, and a correlation between conductors located in the upper crust and known mineral occurrences such as the Ernest Henry mine.

The use of 3D deterministic inversions of MT data is very powerful to image the electrical structure of the mineral system at the crustal scale but lacks resolution to image a realistic sharp cover-basement interface and precludes quantitative assessment of uncertainty around the results.

In this work we propose a workflow to image a geologically realistic cover-basement interface and bring insights on the reliability and robustness of different parts of the model using a probabilistic inversion approach.

We selected a subset of the MT survey and for each site we ran a probabilistic 1D trans-dimensional Markov chain Monte Carlo sampler for estimating subsurface conductivity and its associated uncertainty. These inversions are designed to be robust to non-1D effects present in the data. Next, we performed a petrophysical analysis using available down hole measurements to derive constraints on the electrical conductivities of the different lithologies found in the area. Then these petrophysical constraints, coupled to spatial lateral constraints, are used to fuse the 1D probabilistic ensembles into a 3D posterior ensemble.

The pseudo 3D model obtained is compared to a 3D model derived from a conventional 3D deterministic inversion using the same data to assess the value and validity of the workflow. Preliminary interpretation of the results is performed using petrophysical data and established local geology knowledge. Conclusions around the benefits of this workflow to give a different perspective on the characterization of a mineral system located under cover and to provide basis for future survey planning are presented.
A Social Media Big Data-Based Disaster Assessment Framework for Typhoon-induced Flood: Case Study of Typhoon Lekima
Authors: Tang Jiting , Yang Saini , Wang Weiping
Published: March 2020

In 2019, the typhoon Lekima hit China, bringing strong winds and heavy rainfall to the nine provinces and municipalities on the northeastern coast of China. According to the Ministry of Emergency Management of the People’s Republic of China, Lekima caused 66 direct fatalities, 14 million affected people and is responsible for a direct economic loss in excess of 50 billion yuan. The current observation technologies include remote sensing and meteorological observation. But they have a long time cycle of data collection and a low interaction with disaster victims. Social media big data is a new data source for natural disaster research, which can provide technical reference for natural hazard analysis, risk assessment and emergency rescue information management.

We propose an assessment framework of social media data-based typhoon-induced flood assessment, which includes five parts: (1) Data acquisition. Obtain Sina Weibo text and some tag attributes based on keywords, time and location. (2) Spatiotemporal quantitative analysis. Collect the public concerns and trends from the perspective of words, time and space of different scales to judge the impact range of typhoon-induced flood. (3) Text classification and multi-source heterogeneous data fusion analysis. Build a hazard intensity and disaster text classification model by CNN (Convolutional Neural Networks), then integrate multi-source data including meteorological monitoring, population economy and disaster report for secondary evaluation and correction. (4) Text clustering and sub event mining. Extract subevents by BIRCH (Balanced Iterative Reducing and Clustering using Hierarchies) text clustering algorithms for automatic recognition of emergencies. (5) Emotional analysis and crisis management. Use time-space sequence model and four-quadrant analysis method to track the public negative emotions and find the potential crisis for emergency management.

This framework is validated with the case study of typhoon Lekima. The results show that social media big data makes up for the gap of data efficiency and spatial coverage. Our framework can assess the influence coverage, hazard intensity, disaster information and emergency needs, and it can reverse the disaster propagation process based on the spatiotemporal sequence. The assessment results after the secondary correction of multi-source data can be used in the actual system.

The proposed framework can be applied on a wide spatial scope and even full coverage; it is spatially efficient and can obtain feedback from affected areas and people almost immediately at the same time as a disaster occurs. Hence, it has a promising potential in large-scale and real-time disaster assessment.
Diversity of the Madden-Julian Oscillation
Authors: Chen Guosen , Wang Bin , Liu Fei
Published: March 2020

Madden-Julian Oscillation (MJO) is the dominant mode of atmospheric intraseasonal variability and the cornerstone for subseasonal prediction of extreme weather events. Climate modeling and prediction of MJO remain a big challenge, partially due to lack of understanding the MJO diversity. Here, we delineate observed MJO diversity by cluster analysis of propagation patterns of MJO events, which reveals four archetypes: standing, jumping, slow eastward propagation, and fast eastward propagation. Each type of MJO exhibits distinctive east-west asymmetric circulation and thermodynamic structures. Tight coupling between the Kelvin wave response and major convection is unique for the propagating events (slow and fast propagations), while the strength and length of Kelvin wave response distinguish slow and fast propagations. The Pacific sea surface temperature anomalies can affect MJO diversity by modifying the Kelvin wave response and its coupling to MJO convection. An El Niño state tends to increase the zonal scale of Kelvin wave response, to amplify it, and to enhance its coupling to the convection, while a La Niña state tends to decrease the zonal scale of Kelvin wave response, to suppress it, and to weaken its coupling to the major convection. This effect of background sea surface temperature on the MJO diversity has been verified by using a theoretical model. The results shed light on the mechanisms responsible for MJO diversity and provide potential precursors for foreseeing MJO propagation.
Energetic ion dynamics near the cusp region of Mercury
Authors: Jang Eunjin , zhao Jiutong , Yue Chao , Zong Qiugang , Liu Ying , Liu Zhiyang
Published: March 2020

Energetic ions in Mercury’s magnetosphere are very dynamic, just like in the magnetosphere of Earth. In this study, we have shown two energetic proton observations by MESSENGER near the cusp region of Mercury. For one case, we have observed large flux of energetic protons while the other case has almost no flux, indicating that the near cusp region may trap energetic particles under particular conditions. In order to understand that under what conditions the near cusp region of Mercury could trap energetic particles, we have traced the trajectories of single particle with different energies by using a modeled magnetic field, called KT17. Under different magnetic field geometry, the motions of single particle with various energies are different. The test particles can be trapped around the cusp region when the disturbance activity is strong, generating the magnetic field local minimum near the cusp region while the particles can’t be trapped and escape along the magnetic field through the dawn side cusp when there is little solar activity.
FEM-modelling of ice dynamics without remeshing
Authors: Ahlkrona Josefin , Elfverson Daniel
Published: March 2020

The Finite Element Method (FEM) has become a popular method for numerical ice sheet modelling, partly due to its capability of representing complex geometries. However, there is a limit to just how complicated these geometries can be. In the presence of irregular geometries and moving boundaries like those appearing in glaciology, costly remeshing and low mesh quality may become issues. To overcome these problems, new unfitted sharp interface methods such as CutFEM are being developed by the FEM community. The CutFEM method allows for the boundary to cut through a mesh, without requiring the element nodes to be located on the boundary. In this way simple structured meshes can be used and remeshing is avoided while accuracy and stability is retained. We develop a CutFEM method for the full Stokes equations and apply it to a transient simulation of the Arolla Glacier with both no slip and partial slip conditions at the bed, using a level-set function to track the moving ice surface. We demonstrate accuracy of the method and discuss extensions to modelling ice shelves and moving grounding lines.
Significance of reservoir operation during extreme rainfall event in flood mitigation and water demand management in a metropolitan city of India: a case study
Authors: Panchanthan Anandharuban , La Rocca Michele , Lakshmanan Elango
Published: March 2020

Increasing water demand and climate change poses a great challenge in managing water resources availability. Reservoir operation during heavy rainfall events in an urbanized region is crucial in terms of decision making. The objective of this study is to assess the significance of reservoir operation during extreme rainfall events on flood mitigation and future domestic water supply. One of the major water supply reservoirs in Chennai city was chosen for this study. Rainfall record of recent four decades were analyzed and a major flood event occurred in 2015 was chosen. A combined model of hydrologic-hydraulic processes was carried out using Hydrologic Engineering Centre-Hydrologic Modelling System (HEC-HMS) and a box model based on input-output parameters. These models were calibrated and validated with historical flood events with good performance indications. Four different scenarios were framed for the analysis by targeting reduction in outflow and higher storage in the end of the event. Reducing the reservoir storage in advance and releasing with its maximum capacity at the beginning of the event will reduce the outflow from 5 to 27% and increase the time to peak by 11 to 16 hours. Available hydraulic facilities for higher storage at the end of the event were analyzed. It reveals that with the available facilities, reducing the initial storage from 75 to 50% will help to store 27 to 40% of inflow at the end of the event. Whereas the available hydraulic facilities will not allow to have a 75% of the reservoir storage at the end of this event. New gates can be provided for the safe operation during extreme rainfall events associated with the higher initial storage in the reservoir. Increased storage capacity combined with additional provisions of gates will reduce the outflow by 30% and increase the time to peak by 20 hours with the actual condition. By adapting these reservoir operation strategies, flood mitigation and fresh water augmentation during extreme events can be achieved to a significant extent. The developed combined modelling approach can be used to simulate various combinations of reservoir operations to assess the significance of timely decision on release during extreme rainfall events.

Keywords: flood mitigation, reservoir operation strategies, urban water supply, modelling
Analysis of co-registration performance of KOMPSAT satellite images according to acquisition angles
Authors: Lee Jeongho , Kim Yeji , Yeom Jongmin , Park Seonyoung , Han Youkyung , Kim Taeheon
Published: March 2020

This study analyzed how the co-registration accuracy varies according to the angles of sensors when satellite images are acquired. We used two-step co-registration; coarse co-registration was conducted by using multi-spectral images with relatively lower resolution, and precise fine co-registration was conducted in the region of interest by using panchromatic images. In this study the mutual information method was used because the search area for image matching is restricted by the initial coordinate data in the metadata file, and the mutual information method shows high matching performance in the small search area. We tested the method using data set of 120 combinations with 16 KOMPSAT-3‧3A images acquired in Daejeon, Korea. And we analyzed the effects on the image co-registration accuracy by image acquisition angle factors such as azimuth, incidence, and convergence angles. Experimental results showed that the convergence angle mostly affects on the co-registration accuracy among the angle factors, which shows the overall correlation coefficient with the registration accuracy as 0.59.
Different causes of the delamination on the example of Caucasus and Kyrgyz Tien Shan collision zones.
Authors: Medved Irina , Koulakov Ivan , Buslov Mikhail
Published: March 2020

The causes of delamination of the mantle lithosphere in collision zones is actively debated in the scientific community. The main discussions are focused on the initiation of sinking of the continental lithosphere into the asthenosphere to a depth. Most scientists believe that such kind of immersion is impossible. However, there are several articles showing that this process is nonetheless taking place. For example Kay and Kay, (1993), Faccenda, Minelli, Gerya, (2009), Ueda et. al., (2012) and others propose various mechanisms of delamination, for example: eclogitization of the mafic layer of the lower crust, the effect of convection in the upper mantle, or gradual transition of the oceanic subduction into continental collision. Does the mantle part of the lithosphere sink into the mantle or spread laterally, as described in [for example, Deep Geodynamics, 2001; Bird, 1991; Schmeling and Marquart, 1991]?

To answer these questions, we study deep structures beneath the Caucasus and Kyrgyz Tien Shan collision zones. The studies were carried out on the basis of multiscale seismic tomography methods: regional and global. This approach made it possible to study heterogeneities both in the crust and in the upper mantle. The obtained 3D models of seismic heteroheneities reveal similar features for the both collision regions. Beneath the mountain areas, in the uppermost mantle and lower crust, we observe prominent low-velocity anomalies that possibly indicate thickening of the crust and missing (or strongly thinned) mantle part of the lithosphere. At the edges of the collision zones, we reveal inclined high-velocity anomalies appearing as continuations of the continental plates sinking underneath the collision zones, which can be interpreted as delaminating mantle parts of the continental lithosphere.  Based on joint consideration of the tomography models with the existing models of tectonic evolution, we conclude that the mechanisms of delamination in the considered two regions are different. In Caucasus, the delamination could be gradually transformed from oceanic subduction that ended here approximately ~10-15 Ma. In the case of Tien Shan, the detachment of the mantle lithosphere could be triggered by the plume that existed beneath Central Tien Shan or by the eclogitization of the mafic layer of the lower crust.
Was Australia a sink or source of carbon dioxide in 2015? Data assimilation using OCO-2 satellite data
Authors: Villalobos Yohanna , Rayner Peter , Thomas Steven , Silver Jeremy
Published: March 2020

Estimates of the net CO2 flux at a continental scale are essential to building up confidence in the global carbon budget. In this study, we present the assimilation of the satellite data from the Orbiting Carbon Observatory-2 (OCO-2) (land nadir and glint data) to estimate the Australian CO2 surface fluxes for 2015. We used the Community Multiscale Air Quality (CMAQ) model and a four-dimensional variational scheme. Our preliminary results suggest that Australia was a slight carbon sink during 2015 of -0.15 +- 0.11 PgC y-1 compared to the prior estimate of 0.13 +- 0.55 PgC y-1. The monthly seasonal cycle shows there was not a good agreement between the prior and posterior fluxes in 2015. Our monthly posterior estimates suggest that from May to August, Australia was a sink of CO2 and that from October to December, it was a source of CO2 compared to the prior estimates, which showed an opposite sign. To understand these results more deeply, we aggregated the CO2 surface fluxes into six categories using Land Cover Type Product the Moderate Resolution Imaging Spectroradiometer (MODIS) and divided them into two areas (north and south). Our posterior fluxes aggregated in the southern and northern Australia indicates that most of the uptake of CO2 is driven by grasses and cereal crops. Grasses and cereal crops in these two regions represent -0.11 +- 0.027 and -0.06 +- 0.05 PgC/y respectively. In the southern region, the monthly time series of this category shows that this uptake occurs mainly from June to September, whereas in the north, it occurs from January to March. We evaluate our posterior CO2 concentration against The Total Carbon Column Observing Network (TCCON) and in-situ measurements.  We use the TCCON stations from Darwin, Wollongong, and Lauder (in New Zealand). Amongst the in-situ measurements, we considered stations located at Gunn Point (near Darwin), Cape Grim (in Tasmania) and Iron Bark and Burncluith (in Queensland). Analysis of the monthly biases indicates that CO2 concentration simulated by posterior fluxes are in better agreement with TCCON data compared to in-situ measurements. In general, monthly mean biases in TCCON Darwin are improved by almost 70 per cent. Lauder and Wollongong stations are strongly affected by ocean fluxes which have small prior uncertainty in this inversion. Biases are hence not much improved here. We verify this by relating bias to wind direction. If the winds come from the ocean, fluxes over Australia are less constrained by OCO-2 data. Biases against in situ data are generally not improved by assimilation, suggesting either problems with the transport model or an inability for OCO-2 data to constrain fluxes at scales relevant to these measurements.
Multi-Cross-hole 3-D reverse time migration imaging
Authors: Cheng Fei , Liu Jiangping
Published: March 2020

Cross-well 2-D seismic CT imaging method has been widely used in many fields such as oil-gas exploration and engineering geological exploration, but for the real three-dimensional space, this traditional method can only obtain the two-dimensional velocity profile between the two wells, cannot obtain the lateral geological structure outside the profile; Besides, the seismic signal received from cross-well exploration is the response of geologic body in three-dimensional space, which may be influenced by the geologic body outside the two-well profile, and that will give a result of image distortion and having an effect on geological interpretation. Based on the theory of three-dimensional acoustic wave equation, this paper implements a three-dimensional cross-well reverse-time migration imaging method to obtain the cross-well 3-D geological structure with the observed value from multiple wells by using the first-order velocity-stress acoustic wave equation and firing time imaging conditions. Calculation results of the typical theoretical models show that: The multi-well three-dimensional imaging method adopted in this paper can accurately and effectively realize the cross-well 3-D geological imaging with high resolution and reliable results. Multi-well three-dimensional imaging method can effectively obtain the cross-well three-dimensional structure distribution, which can solve the issue of hard to obtain the transverse structure change by 2-D imaging. It also can solve the imaging problems of big dip angle interface in CT imaging and obtains the true cross-well 3-D geological structure with the multiple well data, which can provide the basis for cross-well 3-D seismic exploration.
Surface urban heat island variation over major Indian cities across different climatic zone
Authors: Mohammad Pir , Goswami Ajanta
Published: March 2020

Surface urban heat island (SUHI) is a major anthropogenic alteration of the urban environment, and its geospatial pattern remains poorly understand over a larger area. SUHI has been investigated in many regions of the world, but the complete understanding of its dynamics over a large area, across different climatic regime is missing, especially in India. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS), land surface temperature (LST) data from 2003 to 2018 is used to investigate the diurnal, seasonal, and interannual variations in the SUHI intensity, difference in urban and rural LST, across 150 major Indian cities situated over different climatic zones. The result shows the presence of surface urban heat/cool island depending upon climatic zones and seasons. The general sequence of mean SUHI intensity observed over different climatic zones is winter nighttime>summer nighttime>winter daytime>summer daytime. During the daytime, the cities situated in tropical monsoon (Am) (coastal cities), hot steppe (BSh), and hot desert (BWh) climatic zone shows a cool urban island, especially in summer. The nighttime SUHI intensity showed less obvious seasonal variations and always showed positive heat intensity. The cities situated in the humid subtropical (Cwa) zone, which is mainly Indo-Gangetic plain and a major hub of the Indian population, shows strong daytime as well as nighttime SUHI intensity. Mann-Kendall and Sen’s slope estimator test are used to detect the long-term trend of SUHI intensity in different climatic zones. The results show the presence of a decreasing trend in most of the cities during the daytime as compared to nighttime in both the summer/winter season.
Effect of air stripping on acidity of mine drainage and the amount of neutralizing agent usage
Authors: Cheong YoungWook , Cho Dong-Wan , Ji Won hyun , Cho Sanghyun
Published: March 2020

Air striping on an acid mine drainage was conducted to measure dissolved CO2 concentration and acidity. The raw water and the disturbed water were neutralized to pH 7.5 and to compare the amount of lime added and sludge volume generated between two waters. The concentration of dissolved CO2 in the raw water was 49 mg/L and the total acidity was 1,018 CaCO3 mg/L. For disturbed water, the CO2 concentration was below 1 mg/L and the total acidity was 882 - 909 CaCO3 mg/L. This was the result of the release of dissolved CO2 into the air. As a result of the removal of CO2, 11% less lime was used and 85% less sludge generation occurred.
Numerical modeling of non-aqueous phase liquids (NAPL) using lumped kinetic parameter approach
Authors: Moon Hee Sun , Lee Dong Hwi , Joo Jin Chul
Published: March 2020

The spill of petroleum-derived contaminants, commonly referred to non-aqueous phase liquids (NAPL), in the subsurface can generate widespread contamination throughout infiltration into the subsoil, and partitioning into one or more phases (gaseous, dissolved, free NAPL, residual NAPL, and entrapped NAPL). Since the movement of NAPL through the vadose zone and saturated zone involves various processes and is affected by many factors, numerical modeling of fate and transport of NAPL including the characteristics of the porous media, the properties of NAPL, as well as the estimation of spilled volume and its distribution in heterogeneous subsurface systems is very complex. Thus, in this study, numerical modeling of NAPL using lumped kinetic parameter approach representing the mean value over the representative elementary volume were evaluated for multicomponent components in NAPL. Modeling predictions with lumped kinetic parameter approach for multicomponent components were validated by comparing to those with literature kinetic parameter for single component. From the results, numerical modeling of NAPL using lumped kinetic parameter approach can predict the multicomponent fate and transport with minimum mass balance error in some cases. Those mass balance errors were clearly dependent on the composition and mole fractions of NAPL, and mass transfer for the soluble compounds under conditions of low NAPL saturation is rate-limited. However, numerical modeling of NAPL using lumped kinetic parameter approach can provide rough insight on fate and transport of multicomponent components in NAPL with reduced effort and time without the need of kinetic and interaction parameters of all components in NAPL. 
Mechanism of the Double peaked El Nino
Authors: Shin Na-Yeon , Kug Jong-Seong , McCormack Felicity S. , Holbrook Neil J.
Published: March 2020

   In the past decades, our understanding of the ENSO phenomenon increased steadily. Especially, one of the most interesting topics was the El Niño type because of the different global impacts. The classic classification is the two types of the El Niño and there are various terms to refer this. The conventional El Niño is called the Cold tongue El Niño or the Eastern pacific El Niño. And the other type of the El Niño is called the Warm pool El Niño, the Central pacific El Niño, the El Niño Modoki or the dateline El Niño. However, in Coupled Model Intercomparison Project version 5 (CMIP5) Coupled General Circulation Models (CGCMs) results, those have been shown the Double peaked El Niño events which are the new type of the El Niño due to the climatological cold tongue bias. Double peaked El Niño events are defined as a positive sea surface temperature anomalies are separated into two centers (in Western and Eastern Pacific) and grow individually and simultaneously, and the peak of SST anomalies exceeds the threshold.

   Double peaked El Niño events are found in not only the models, but also the observations. But there are no dynamical analysis of observations. In this study, the mechanism giving rise to Double peaked El Niño in observation is examined by analyzing the mixed layer heat budget equation and comparing with the Warm Pool El Niño and Cold tongue El Niño.

   The warm SST anomalies of the western peak and the eastern peak are caused by different dynamic mechanism. Western peaks of Double peaked El Niño are similar to the Warm Pool El Niño. Those can be developed by Zonal advection feedback terms and negative anomalous wind speed, whereas eastern peaks of Double peaked El Niño are different from Warm pool El Niño. Thermocline feedback term considerably contribute to the occurrence of eastern peak. Differences of intensity of the precipitation(4-8N, 195-225E) derive other significant differences of the zonal wind stress(5S-5N, 170-200E), sea level(5S-5N, 230-250E) and zonal current(5S-5N, 230-250E). Thus, the process above can induce the eastern peak of the Double peaked El Niño.
Assessing crop yield and crop water productivity and optimizing irrigation scheduling of winter wheat in the Haihe plain using hydrological model
Authors: Sun Chen , Xu Xu
Published: March 2020

Haihe plain is an important food production area in China, facing an increasing water shortage. The water used for agriculture accounts for about 70% of total water resources. Thus, it is critical to optimize the irrigation scheduling for saving water and increasing crop water productivity (CWP). This study firstly simulated crop yield and CWP for winter wheat in historical scenario during 1961-2005 for Haihe plain using previously well-established SWAT model. Then scenarios under historical irrigation (scenario 1) and sufficient irrigation (scenario 2) were respectively simulated both with sufficient fertilizer. The crop yield in scenario 2 was considered as the potential crop yield. The optimal irrigation scheduling with sufficient fertilizer (scenario 3) was explored by iteratively adjusting irrigation scheduling based on the scenario 1 and previous studies related to water stress on crop growth. Results showed that net irrigation amount was reduced 23.1% in scenario 3 for winter wheat when compared with scenario 1. The CWP was 12.1% higher with very slight change of crop yield. Using optimal irrigation scheduling could save 8.8×108 m3 irrigation water and reduce about 16.3% groundwater over-exploitation in winter wheat growth period. The corresponding yield was 18.5% less than potential yield for winter wheat but using less irrigation water. Therefore, it could be considered that the optimal irrigation was reasonable, which provided beneficial suggestions for increasing efficiency of agricultural water use with sustainable crop yield in Haihe plain.
Risk and Vulnerability Assessment of Power grid under Seismic Hazards
Authors: Li Kaiwen , Liu Kai , Wang Ming
Published: March 2020

Abstract: Power grids are one of the most important and complex infrastructure systems in our society. The components of power grid systems are susceptible to damage due to natural hazards and may lead to cascading failures of the system. Here, for the first time, we propose an integrated risk assessment framework for power grid system that combines: (1) geospatial and voltage level information of Chinese power grid and corresponding location of transmission towers; (2) stochastic earthquake scenarios that are generated based on a seismicity model and the Monte Carlo method and (3) cascading failure model to analyze the number of affected population under various power grid initial loads and capacities. This methodology is employed to evaluate the seismic risk of Chinese power grid system, where affected population is regarded as vulnerability metrics. The results show that Beijing, Hebei province and central area of Shandong and Qinghai province, eastern area of Sichuan province as well as southern area of Xinjiang province have higher seismic risk, which indicates high-aseismic measures should be adopted in the aforementioned areas. Meanwhile, we also found that the increase of capacity of the whole power grid will result in and increasing robustness of the power grid system and decreasing affected population.
Characteristics of fluid-flow migration(bleached rock) around major structures in a reservoir-cap rock system, SE Utah, USA
Authors: Ko Kyoungtae
Published: March 2020

Bleached rocks are commonly formed from CO2-saturated water leakage to the surface. It could provide opportunities to understand the mechanisms and controlling factors associated with injected and sequestrated CO2 leakages as well as fluid flow in the subsurface. In this study, we investigated the various bleaching patterns and their related structures in order to understand the characteristics of fluid-flow migration around the major structures. Also, we examined the effects of lithology and structural characteristics on fluid flow in detail along and around the major structures. For this purpose, we analyzed bleaching characteristics of multiple layered sedimentary rocks around two major faults (Moab and Salt Wash Faults) and fold axes (Green river anticline system) based on field observations and quantitative measurements (scanline survey and permeability) in the exhumed reservoir-cap rock systems in SE Utah, USA. The results showed that strongly bleached layers of sedimentary rock have a higher density of deformation bands compared to unbleached layers. This is consistent with the general property of deformation bands that frequently develop in layers with higher porosity and permeability. Although almost all fault zones act as conduits for fluid flow, some fault zones filled with clay-rich gouges could impede fluid flow. In addition, the internal sealing characteristics of the layer boundaries such as bedding planes could be important factors as they can act either as a pathway or a barrier for lateral fluid flow depending on the existence of filling materials such as calcite or kerogen. Our research may be useful for assessing CO2 leakage in oil reservoirs or CO2 sequestration sites located in a reservoir-cap rock system of sedimentary basins.
Impact of Soil Moisture on Winter 2-m Temperature Forecast in Northern China
Authors: Zhong Ji-Qin , Lu Bing , Wang Wei , Huang Cheng-Cheng , Yang Yang
Published: March 2020

 The causes of the underestimated diurnal 2-m temperature range and the overestimated 2-m specific humidity in Northern China’s winter in the Rapid-refresh Multi-scale Analysis and Prediction System - Short Term (RMAPS-ST) system are investigated. Three simulations based on RMAPS-ST are conducted from Nov. 1st, 2016 to Feb. 28th, 2017. Further analyses show that the partitioning of surface upward sensible heat fluxes and downward ground heat fluxes might be the main contributing factor in 2-m temperature forecast biases. In this study, two simulations are conducted to examine the effect of soil moisture initialization and soil hydraulic property on the 2-m temperature and 2-m specific humidity forecast biases. Firstly, the High-Resolution Land Data Assimilation System (HRLDAS) is used to provide an alternative soil moisture initialization, and the result shows that the drier soil moisture leads to noticeable change in energy partition at the land surface, which in turn results in improved prediction of the diurnal 2-m temperature range, although it also enlarges the 2-m specific humidity bias in some parts of the domain. Secondly, a soil texture dataset developed by Beijing Normal University (BNU) and a revised hydraulic parameters are applied to provide a more detailed description of soil properties, which could further improve the 2-m specific humidity biases. In summary, the combination of using optimized soil moisture initialization, updated soil map and revised soil hydraulic parameters can help improve the 2-m temperature and 2-m specific humidity prediction in RMAPS-ST.
Detecting recent creeping landslide activity in central Taiwan by multi-temporal InSAR technique
Authors: Hu Jyr-Ching , Lu Chiao-In
Published: March 2020

The main objective of this study is to present the progress and state-of-the-approaches of PSInSAR with Sentinel-1 radar images to detect the creeping activity of the potential large landslides revealed by LiDAR in the mountainous area of the slate belt in central Taiwan. We choose Qingjing and Lushan area to process the Multi-Temporal InSAR (MTI) to capture the signals the creeping activity associated with the heavy rainfall events. First, we carry out the feasibility analysis to predict whether the MTI analysis is suitable for detecting the potential persistent scatterers (PS) and test the sensitivity with the effect of layover and shadowing resulted from mountainous topography in central Taiwan. In addition, we also take the effect of land cover on PS distributions into account. Second, we set a threshold of LOS (line of sight) velocity of creeping activity to assess the state of activity. Then we make a Vslope for projection of the LOS velocity along the down-slope direction for steep slope located in the potential landslide area. Furthermore, both the ascending and descending orbits are used to get two LOS velocities which allows us to resolve the E–W and vertical velocity components in order to compare with the tectonic motion due to the mountain building process in slate belt. Finally, the analysis in time series of PSInSAR is carried out for the evolution of creeping events in study area. In this study, we also want to improve the efficiency of remote sensing products for operational monitoring with integration of SAR/InSAR products with numerical and analytical geotechnical models for stability analysis of large potential landslide area detected by geomorphological features from LiDAR-derived DEM.
GGOS Coordinating Office – Recent Achievements and Activities
Authors: Sehnal Martin , Craddock Allison , Elger Kirsten
Published: March 2020

The International Association of Geodesy’s (IAG) Global Geodetic Observing System (GGOS) is managed administratively by the GGOS Coordinating Office, based at the Austrian Federal Office of Metrology and Surveying (BEV). The director of GGOS Coordinating Office (CO) supports the Executive Committee, the Coordinating Board and the Science Panel as well as he ensures coordination of the activities of the various GGOS components like the Bureau of Products and Standards (BPS), the Bureau of Networks and Observations (BNO) and the three GGOS Focus Areas.

The Coordinating Office ensures information flow, maintains documentation of GGOS activities, and manages specific assistance functions that enhance the coordination across all areas of GGOS, including coordination among IAG Services and support for workshops. The Coordinating Office, in its long‐term coordination role, ensures that the GGOS components contribute to GGOS and its stakeholder community in a consistent and continuous manner. The Coordinating Office also maintains, manages, and coordinates the GGOS web- and social media presence as well as outreach and external engagement. In 2020 the current GGOS website (www.ggos.org) will be refreshed and redesigned to optimize usability and ease of navigation. The website will serve as a source of information about GGOS, geodetic data, products, and services, as well as other non-technical resources for the IAG community.

On behalf of the GGOS community, the Coordinating Office manages external relations and engagement with stakeholder organizations such as the Group on Earth Observations (GEO), the Committee on Earth Observation Satellites (CEOS) and the International Science Council (ISC) World Data System (WDS). In this capacity, the Office also identifies opportunities to link geodesy with relevant United Nations frameworks and other instruments of engagement, such as the Sendai Framework for Disaster Risk Reduction and the UN-GGIM-World Bank Integrated Geospatial Information Framework.

The Coordinating Office also works to identify opportunities for improved coordination and advocacy within the geodetic community, establishing the Working Group on “Digital Object Identifiers (DOIs) for Geodetic Data Sets” in 2019. This working group consists of more than 20 members affiliated with IAG Services, working to establish usage parameters and advocate for the consistent implementation of DOIs across all IAG Services and in the greater geodetic community.
Hydrodynamic Simulation of Seasonal Fluvial Process over a Large Catchment
Authors: Tong Xue , Liang Qiuhua , Wang Gang
Published: March 2020

Fluvial flooding induced by intense or prolonged rainfall poses a regular threat to people’s lives and properties in almost every part of the world. Modelling provides an essential tool for simulating and predicting the hydrological processes from rainfall-runoff to flooding driven by rainfall. Prediction of seasonal or longer-term fluvial processes over large catchments has traditionally been carried out using lumped/distributed hydrological models. However, these traditional hydrological models do not consider strict momentum conservation and they are not suited for accurate simulation of highly transient and dynamic rainfall-runoff and flooding process. On the other hand, sophisticated hydraulic/ hydrodynamic models have been widely used for modelling of flood inundation including those violent flash floods from intense rainfall. But due to their inhibitive computational cost and incapability in representing certain hydrological processes, no attempt has been reported to use a fully 2D hydrodynamic model to simulate long-term fluvial processes to provide more detailed information for the analysis of flood dynamics and subsequent impact on the environment.

Therefore, this work aims to further develop and test a hydrodynamic model to simulate seasonal fluvial processes in a large catchment. The proposed long-term fluvial processes modelling system is based on the High-Performance Integrated hydrodynamic Modelling System (HiPIMS). HiPIMS solves the full 2D nonlinear shallow water equations using a finite volume shock-capturing numerical method, which is further accelerated by modern GPUs for large-scale and long-term simulations. Surface storage, overland flow and flow dynamics are automatically captured by running simulations on high-resolution topographic data. New model components are developed and coupled to HiPIMS to account for infiltration and evaporation. For infiltration, the Green-Ampt method and curve number method are implemented and compared. The enhanced HiPIMS is applied to reproduce, at 20m resolution, the seasonal fluvial processes including flooding and recovery periods in the 2500km2 Eden Catchment, England for three months.

The simulation results are compared with gauge measurements of water level and discharge across the catchment to demonstrate the model’s capability in supporting long-term simulations. More simulations have been also carried out to investigate the model sensitivity to key model parameters, e.g. grid resolution, friction, infiltration and evaporation parameters.

 
A 45 kyr laminae record from the Dead Sea: Implications for basin erosion and floods recurrence
Authors: Waldmann Nicolas , Lu Yin , Bookman Revital , Marco Shmulik
Published: March 2020

Recording and analyzing how climate change impacts flood recurrence, basin erosion, and sedimentation can improve our understanding of these systems. The aragonite-detritus laminae couplets comprising the lacustrine formations that were deposited in the Dead Sea Basin are considered as faithful monitors of the freshwater supply to the lakes. We count a total of ~5600 laminae couplets deposited in the last 45 kyr (MIS3-MIS1) at the Dead Sea depocenter, which encompass the upper 141.6 m of the ICDP Core 5017-1. The present study shows that aragonite and detritus laminae are thinner and occur at high frequency during MIS 3-2, while they are much thicker and less frequent during MIS 1. By analyzing multiple climate-connected factors, we propose that significant lake-level drops, enhanced dust input, and low vegetative cover in the drainage basin during the last deglaciation (22-11.6 ka) have considerably increased erodible materials in the Dead Sea watershed. We find a decoupling existed between the significant lake-level drop/lake size reduction and lamina thickness change during the last deglaciation. We argue that during the last glacial and the Holocene, the variation of lamina thickness at the multiple-millennium scale was not controlled directly by the lake-level/size change. We interpret this decoupling implying the transport capacity of flash-floods is low and might be saturated by the oversupply of erodible materials, and indicating a transport-limited regime during the time period. We suggest that the observed thickness and frequency distribution of aragonite-detritus laminae points to the high frequency of small-magnitude floods during the last glacial period, in contrast to low frequency, but large-magnitude floods during the Holocene.