bluuebunny/crossref_metadata_2025 huggingface dataset:
Land use change and management of a Duric Histic Placaquand in Southern Chile: effects on biological properties and greenhouse gas emissions
Authors: Paulino Leandro , Beas Nelson , Dec Dorota , Zúñiga Felipe , Thiers Oscar , Martínez Oscar , Dörner José
Published: March 2020

Aquands are shallow depth and frequently waterlogged volcanic ash soils, presenting seasonal dynamics of water content in the soil profile. Land use change and management are expected to alter the Aquands biological activity due to their impact to water/air relationships as well as nutrient dynamics and greenhouse gases emissions. In southern Chile (41°26’S;73°07’W; 70 m a.s.l.), soil biological processes related to C- and N cycles, as well as greenhouse gas effluxes were assessed in relation to historical land use change and a drainage set in a naturalized grassland for animal husbandry. Disturbed soil samples were obtained in order to evaluate soil respiration, N mineral dynamics (NH4+ and NO3-), denitrification, nitrate reductase activity. Static-closed chambers were installed in the field to assess fluxes of CO2, N2O and CH4 from the soil surface at different seasons of the year with contrasting water table depths. Soil respiration responded to the historical land use change and draining effects. The aerobic and anaerobic biological processes related to soil nitrogen dynamics were less sensitive than respiration, and showed arbitrary effects according to the current use and management of the Aquand. Soil surface fluxes of greenhouse gases showed similar patterns, where CO2 emissions responded temporarily to land use, while N2O and CH4 did not respond conclusively. The content of soil organic carbon associated to the structural changes derived from land use change (e.g. fire clearance) and soil management (e.g. animal trampling) are plausible parameters to explain the variations of CO2 emissions from Aquand soils surface, while other elements such as microbial community and the ferrous wheel hypothesis, should be investigated in order to explain the biological responses and trace greenhouse gases emissions.
The long-range transport of African mineral dust to the Amazon basin
Authors: Wang Xurong , Ma Nan , Prass Maria , Pöhlker Christopher , Wang Qiaoqiao
Published: March 2020

Being the largest mineral dust source, Africa contributes over half of the global mineral dust emission. The trans-Atlantic transport of the large amount of mineral dust is shown to enter the Amazon basin frequently, not only perturbing the near pristine condition in the Amazon during the wet season, but also fertilizing the Amazon rainforest due to dust deposition and associated nutrients input. In this study, we use a global chemical transport model (GEOS-Chem) to simulate the emission, the long-range trans-Atlantic transport, and the deposition flux of African mineral dust to the Amazon basin during the period of 2013-2017, with observational constraints from AERONET data, MODIS data, as well as the observation from the Amazon Tall Tower Observatory (ATTO). With optimized size distribution of African dust, we improve the simulation of dust over both source (north Africa) and remote region (Amazon basin). The trans-Atlantic transport of African dust reaching the Amazon Basin generally occurs in winter and spring (Northern Hemisphere) associated with the northeasterly trade wind advection. In winter, the transport of dust layer occurs below 2 km height while in other seasons it occurs between 1 Km and 3 Km. With average annual emission of 0.78 (±0.14) Pg a-1, African dust entering the amazon basin could reach 3.93 (± 0.76) ug m-3 at ATTO, account for 19% (± 2.5%) of total particle concentrations. However, the contribution could be up to 91% during strong dust events. Assuming mass fraction of 4.4% and 0.082% of iron and phosphorus in the mineral dust, we estimate an annual mass flux of 35.3 (± 4.49) mg m-2 a-1 and 0.66 (± 0.084) mg m-2 a-1 of iron and phosphorus deposit in the Amazon rainforest, respectively.
Automatic Monitoring of Mines Mining based on Multitemporal Remote Sensing Image Change Detection
Authors: Li Chengyi
Published: March 2020

For the country and human society, it is a very important and meaningful work to make the mines mining controlled and rationally. Otherwise, illegal mining and unreasonable abandonment will cause waste and loss of resources. With the features of convenient, cheap, and instantaneous, remote sensing technology makes it possible to automatic monitoring the mines mining in large-scale.

We proposed a mine mining change detection framework based on multitemporal remote sensing images. In this framework, the status of mine mining is divided into mining in progress and stopped mining. Based on the multitemporal GF-2 satellite data and the mines mining data from Beijing, China, we have built a mines mining change dataset(BJMMC dataset), which includes two types, from mining to mining, and from mining to discontinued mining. And then we implement a new type of semantic change detection based on convolutional neural networks (CNNs), which involves intuitively inserting semantics into the detected change regions.

We applied our method to the mining monitoring of the Beijing area in another year, and combined with GIS data and field work, the results show that our proposed monitoring method has outstanding performance on the BJMMC dataset.
Evaluation of Sentinel-3A SAR Altimetry Observations over the Taiwan coastal region
Authors: Kao Huan Chin , Kuo Chung Yen , Shum Ck , Yi Yuchan
Published: March 2020

Pulse-limited radar altimeters have been proven to be an excellent data source in oceanography for monitoring sea surface heights and inland water surface elevations since the 1990s. However, the measurements of conventional altimetry missions in coastal areas present the principal problems related to the inherent limitations of this technique such as wider footprint resulting in contaminated waveforms and relatively unreliable media and geophysical corrections. The European Space Agency (ESA) and the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) joint mission Sentinel-3A, launched in February 2016, is the first altimetry mission to provide 100% global coverage of ocean observations in Synthetic Aperture Radar (SAR) mode. The Sentinel-3A carries a dual-frequency (Ku- and C-band) Synthetic Aperture Radar Altimeter (SRAL) with a new on-board tracking system (open-loop tracking mode) to employ SAR altimetry technologies providing finer along-track spatial resolution up to ~300 m. Compared with the similar mission Cryosat-2, Sentinel-3A has a better ability to observe the global monitoring of ocean dynamics with a shorter repeat cycle of 27 days and less affected by topography in contaminated waveforms from coastal regions due to open-loop tracking mode with a good prior surface elevation estimate on-board. In this study, the SAR altimetry observations of Sentinel-3A over the Taiwan coastal region were reprocessed by a proposed retracking strategy to obtain more accurately retrieved sea level observations. The main objective of this study is to evaluate the performance of Sentinel-3A in coastal observation by using a near-by tide gauge measurements or other altimetry mission like SARAL/Altika and Jason-3.
What drives the decline in groundwater table? A story of Edendale in New Zealand
Authors: Yang Jing , Rajanayaka Channa , Kees Lawrence
Published: March 2020

The Edendale terrace aquifer in Southland New Zealand has experienced a declining trend of groundwater table over the past two decades. Water abstraction has increased over this time and is associated with farming development, intensification and increased production of local industry. Coincident with an increase of groundwater abstraction is a decrease in annual precipitation. Current granted water allocation is ~55% of the allowable limit of 15% of land surface recharge. Determining the main driver of the declining groundwater table is a first step to improving the sustainability of water use in this area.

In this study, we combined a statistical method and physically based modelling method to analyse the main driving force. In the statistical method, the relationship between precipitation, groundwater abstract, and groundwater table over the past two decades have been analysed and the contributions from decreasing precipitation and increasing groundwater abstract were quantified. In the physically based method, a groundwater model (MODFLOW) was coupled with a hydrologic model (TopNet) to simulate the groundwater flow, and scenarios of groundwater abstract and precipitation were assessed using this coupled hydrologic model and groundwater model.

The modelling result above is used for sustainable water allocation management by the regional government, and this methodology can be used for groundwater management in other regions with declining groundwater table.
A Novel Framework for Hydropower Scheduling Under Uncertainty
Authors: Stark Greg , Barrows Clayton , Brinkman Greg , Carney Shaun , Triana Enrique
Published: March 2020

Although there have been numerous advances in production cost modeling techniques over past decade, the characterization of hydropower operations has remained relatively unsophisticated in common usage, largely ignoring the water-energy nexus.  We believe that there are two key reasons for this simple representation.  First, hydropower operational constraint data (including technical constraints, water-use priorities and rules, environmental constraints, and drought mitigation plans) are often not readily available or easily expressed in the Mixed Integer Linear Programming (MILP) problems that represent unit commitment and economic dispatch of generating assets.  Second, the water availability uncertainties involved in hydropower planning often span many days, months, or even years.  These uncertainties do not align well with the day-ahead unit commitment problem that is solved for grid operations.  This makes it difficult for unit commitment models to comprehensively include and make best use of water and hydropower production.

 

Recent trends toward increased reliance on variable generation and emerging concerns about the impacts of climate and weather uncertainty on infrastructure systems have highlighted the growing need for improved hydropower modeling capabilities within grid operations models.  To address this challenge, the United States Department of Energy’s National Renewable Energy Laboratory (NREL) is working with RTI International to develop an open-source modeling platform that enables the flexible specification of power system scheduling problems, including enhanced representation of water resource availability, hydropower constraints, and multi-stage stochastic programming capabilities.  The platform combines the flexibility of NREL’s Scalable Integrated Infrastructure Planning (SIIP) grid operations model with a generalized river basin decision support system and network flow model (MODSIM-DSS), allowing optimization across both grid and river basin operations.  Our work will leverage this novel framework to explore emerging approaches to scheduling hydropower under uncertainty at time scales raging from minutes to decades. Demonstration use cases focus on research and enhanced planning in the water-energy nexus domain, including how to predict and make best use of water availability for hydropower production, discover tradeoffs between water supply and hydropower generation, and how to predict and quantify the space-time dependencies and feedback connections between variable generation (wind and solar), the water cycle and other weather-related events, and hydropower.
The forced response of the El Niño–Southern Oscillation-Indian monsoon teleconnection in ensembles of Earth System Models
Authors: Bodai Tamas , Drotos Gabor , Herein Matyas , Lunkeit Frank , Lucarini Valerio
Published: March 2020

We study the teleconnection between the El Niño–Southern Oscillation (ENSO) and the Indian summer monsoon (IM) in large ensemble simulations, the Max Planck Institute Earth System Model (MPI-ESM) and the Community Earth System Model (CESM1). We characterize ENSO by the JJA Niño 3 box-average SST and the IM by the JJAS average precipitation over India, and define their teleconnection in a changing climate as an ensemble-wise correlation. To test robustness, we also consider somewhat different variables that can characterize ENSO and the IM. We utilize ensembles converged to the system’s snapshot attractor for analyzing possible changes in the teleconnection. Our main finding is that the teleconnection strength is typically increasing on the long term in view of appropriately revised ensemble-wise indices. Indices involving a more western part of the Pacific reveal, furthermore, a short-term but rather strong increase in strength followed by some decrease at the turn of the century. Using the station-based SOI as opposed to area-based indices leads to the identification of somewhat more erratic trends, but the turn-of-the-century “bump” is well-detectable with it. All this is in contrast, if not in contradiction, with the discussion in the literature of a weakening teleconnection in the late 20th century. We show here that this discrepancy can be due to any of three reasons: ensemble-wise and temporal correlation coefficients used in the literature are different quantities; the temporal moving correlation has a high statistical variability but possibly also persistence; MPI-ESM does not represent the Earth system faithfully.
The Magnetics Information Consortium (MagIC) Data Repository: Successes and Continuing Challenges
Authors: Jarboe Nicholas , Minnett Rupert , Constable Catherine , Koppers Anthony , Tauxe Lisa
Published: March 2020

MagIC (earthref.org/MagIC) is an organization dedicated to improving research capacity in the Earth and Ocean sciences by maintaining an open community digital data archive for rock and paleomagnetic data with portals that allow users access to archive, search, visualize, download, and combine these versioned datasets. We are a signatory of the Coalition for Publishing Data in the Earth and Space Sciences (COPDESS)'s Enabling FAIR Data Commitment Statement and an approved repository for the Nature set of journals. We have been in collaboration with EarthCube's GeoCodes data search portal, adding schema.org/JSON-LD headers to our data set landing pages and suggesting extensions to schema.org when needed. Collaboration with the European Plate Observing System (EPOS)'s Thematic Core Service Multi-scale laboratories (TCS MSL) is ongoing with MagIC sending its contributions' metadata to TCS MSL via DataCite records.

Improving and updating our data repository to meet the demands of the quickly changing landscape of data archival, retrieval, and interoperability is a challenging proposition. Most journals now require data to be archived in a "FAIR" repository, but the exact specifications of FAIR are still solidifying. Some journals vet and have their own list of accepted repositories while others rely on other organizations to investigate and certify repositories. As part of the COPDESS group at Earth Science Information Partners (ESIP), we have been and will continue to be part of the discussion on the needed and desired features for acceptable data repositories.

We are actively developing our software and systems to meet the needs of our scientific community. Some current issues we are confronting are: developing workflows with journals on how to publish the journal article and data in MagIC simultaneously, sustainability of data repository funding especially in light of the greater demands on them due to data policy changes at journals, and how to best share and expose metadata about our data holdings to organizations such as EPOS, EarthCube, and Google.
Modeling dust sources, transport, and radiative effects at different altitudes over the Tibetan Plateau
Authors: Hu Zhiyuan , Huang Jianping , Zhao Chun , Jin Qinjian , Ma Yuanyuan , Yang Pen
Published: March 2020

Mineral dust plays an important role in the climate of the Tibetan Plateau (TP) by modifying the radiation budget, cloud macro- and microphysics, precipitation, and snow albedo. Meanwhile, the TP with the highest topography in the word can affect intercontinental transport of dust plumes and induce typical distribution characteristics of dust at different altitudes. In this study, we conduct a quasi-global simulation to investigate the characteristics of dust source contribution and transport over the TP at different altitude by using a fully coupled meteorology-chemistry model (WRF-Chem) with a tracer-tagging technique. Generally, the simulation reasonably captures the spatial distribution of satellite retrieved dust aerosol optical depth (AOD) at different altitudes. Model results show that dust particles are emitted into atmosphere through updrafts over major desert regions, and then transported to the TP. The East Asian dust (mainly from Gobi and Taklamakan deserts) transports southward and is lifted up to the TP, contributing a mass loading of 50 mg/m2 at 3 km height and 5 mg/m2 at 12 km height over the northern slop of the TP. Dust from North Africa and Middle East are concentrated over both northern and southern slopes below 6 km, where mass loadings range from 10 to 100mg/m2 and 1 to 10 mg/m2 below 3 km and above 9 km, respectively. As the dust is transported to the north and over the TP, mass loadings are 5-10 mg/m2 above 6 km.

The imported dust mass flux from East Asia to the TP is 7.9 Tg/year mostly occuring at the heights of 3–6 km. The North African and Middle East dust particles are transported eastward following the westerly jet, and then imported into the TP at West side with the dust mass flux of 7.8 and 26.6 Tg/year, respectively. The maximum mass flux of the North African dust mainly occurs in 0–3 km (3.9 Tg/year), while the Middle East within 6–9 km (12.3 Tg/year). The dust outflow occurs at East side (–17.89 Tg/year) and South side (–11.22 Tg/year) of the TP with a peak value (8.7 Tg/year) in 6–9 km . Moreover, the dust mass is within the size range of 1.25~5.0
Single station GNSS tomography as a replacement of mapping function for high precision troposphere radio wave delay correction
Authors: Peng Feng , Fei Li , Barriot Jean-Pierre , Jianguo Yan , Fangzhao Zhang , Mao Ye
Published: March 2020

With its relatively low cost, high availability and continuous observation ability, zenith delays from GPS combined with mapping function have been used in satellite tracking media calibration since early 2000. The mapping functions are used to model elevation dependency of radio wave delays in the troposphere. It assumes that the ratio of signal slant delay over zenith delay is less variable w.r.t time and location than the signal delay itself. Thus the parameters of signal delay elevation dependency can be modeled and unknowns of the tropospheric delay were reduced. However, the parameterization comes with a loss of accuracy. For example, the state-of-art VMF series mapping functions have a time resolution of 6 hours, which means variations that took place in less than 6 hours are smoothed. Nowadays GPS has evolved to multi-constellation GNSS with many more satellites in visibility. Here we propose a single station GNSS tomography algorithm for radio wave delay correction by directly using slant delays. This algorithm can extract the information of the troposphere variations in all the signal directions of GNSS observations with high time resolution. Thus it will be beneficial to the radio wave delay correction of precise satellite tracking. We assess the performance of this algorithm with a collocated water vapor radiometer.
Geodetic inversion of complex fault geometries for strong earthquakes
Authors: Zhang Yong , Xu Yueyi , Wang Rongjiang
Published: March 2020

The fault geometry closely controls earthquake rupture process. Previous seismic inversion of the fault geometry is to derive the multiple-point moment tensor solutions. Because of the trade-off between the moment tensor and rupture velocity, the inversion has high instabilities. In contrast, geodetic inversion has less unknowns, since there is no need to solve for rupture velocity. But from the elastic dislocation theory, the relations between the surface deformation and sub-fault parameters (i.e. strike, dip and rake) are nonlinear. In this study, we develop a linear technique to invert geodetic data for sub-fault moment tensors. From the sub-fault moment tensor solutions, the strike, dip, rake, and their spatial variations can be estimated, which provide valuable information for assessing the complexities in fault geometry. We applied this technique to several significant earthquakes, i.e., the 2008 Mw7.9 Wenchuan earthquake, the 2015 Mw7.8 Gorkha earthquake, and the 2017 Mw6.5 Jiuzhaigou earthquake. The results of the 2008 Wenchuan earthquake suggest that the strike, dip and rake are all variable from southwest to northeast, which are well consistent with the aftershock distributions and mechanisms. The dip variations of the 2015 Gorkha earthquake suggest the earthquake has ruptured a listric fault (dep decreases with depth). Particularly, a dip anomaly appears in the northeast corner of the rupture area, indicating a geometric barrier accounting for the slip gap between the mainshock and largest Mw7.3 aftershock. For the 2017 Jiuzhaigou earthquake, two right-stepping and left-lateral strike-slip segments were distinguished. Accordingly, a compressional step-over was identified between the two segments.
Nature of Elsässer Variables in the slow solar wind turbulence
Authors: Wang Xin , Tu Chuanyi , He Jiansen
Published: March 2020

Elsässer Variables z± are widely considered as outward and inward propagating Alfvén waves in the solar wind turbulence study. It is believed that they can interact nonlinearly with each other to generate energy cascade. However, z− variations sometimes show a feature of convective structures or a combination of white noise and pseudo-structures. Here we present the amplitude of z± in σc (normalized cross helicity) - σr (normalized residual energy) plane in order to get some information on the nature of z±. Measurements from the WIND spacecraft in the slow solar wind during 2007-2009 are used for analysis. In each interval with length of 20 min, we calculate σc, σr, and consider the variance of z± as the amplitude of them for the given interval. We find that in the σc-σr plane, the level contours of the average z- amplitude present a feature of nearly horizontal stratification, which means that the amplitude of z- is independent of the value of σc, and is just related to σr. The horizontal-stratification feature suggests that z- could be convective structures. While the level contours of the average amplitude of z+ are approximately concentric semicircles, and the circle with larger radius corresponds to larger z+ amplitude. It indicates that z+ represents Alfvén waves. The nature of z± in the slow wind here will help us to understand more about the cascade process in the solar wind turbulence.
Traveling with Science
Authors: Cureton Sarah , Nichols Mel E. , Weathersbee Cassandra
Published: March 2020

Incorporating travel into academic curriculum provides a significantly greater depth of understanding and interest in content material. Academically, the students are engaged, experiencing enrichment at a hands-on level and participating in open discussion with experts in the designated field. Travel within academic curricula is a proven method to help students bridge the gap between textbook and retention. Additionally, content based travel is one method of reaching the reluctant learner. 

A group of Earth Science educators (Cureton, M. Nichols, Weathersbee) at Patriot High School have collaboratively developed a travel-based, cumulative portfolio project for Earth Science students. The students are provided with multiple travel opportunities throughout the academic year to cater to specific curricula interests. Examples of trips include local museums, hikes, planetariums, caverns, and water treatment facilities. Students are required to select two of up-to ten travel opportunities (but can attend as many as they desire) and are provided content-based experiences that align specifically with the Earth Science curriculum. The required field-trips are provided outside of normal school hours to avoid absences from other classes during the school day. Multiple trip opportunities are provided to the students for less scheduling conflicts. 

While traveling, students are provided with guided, thought-provoking questions in the form of an activity. These activities are used to stimulate the thought process and guide the student-learner toward desired information while on travel. The activity and a written reflection are required as the final portfolio submission. The students are able to reflect and relate the specific travel opportunity to a branch of Earth Science, discuss advancements made in the field of study and connect the trip to one of Patriot High Schools seven leadership pillars. The Earth Science Portfolio is a capstone project that is cumulative throughout the academic school year. The students are given in-class opportunities to conduct scientific research and are guided on proper scientific writing techniques while completing the assignment.  

These on-going travel opportunities have provided not only a method for students to experience science first-hand but also motivated students toward specific career paths and interests. This Earth Science Portfolio has been modeled at the county level and has generated excitement throughout the student-body at Patriot High School.
Effects of Trees on Pedestrian Wind Comfort in an Urban Area Using a CFD model
Authors: Kang Geon , Kim Jae-Jin
Published: March 2020

This study investigated the effects of trees on the pedestrian wind comfort in the Pukyong National University (PKNU) campus. For this, we implemented the tree’s drag parameterization scheme to a computational fluid dynamics (CFD) model and validated the simulated results against a field measurement. The CFD model well reproduced the measured wind speeds and TKEs in the downwind region of the trees, indicating successful implementation of the tree drag parameterization schemes. Besides, we compared the wind speeds, wind directions, and temperatures simulated by the CFD model coupled to the local data assimilation and prediction system (LDAPS), one of the numerical weather prediction models operated by the Korean Meteorological Administration (KMA) to those observed at the automated weather station (AWS). We performed the simulations for one week (00 UTC 2 – 23 UTC 9 August 2015). The LDAPS overestimated the observed wind speeds (RMSE = 1.81 m s–1), and the CFD model markedly improved the wind speed RMSE (1.16 m s–1). We applied the CFD model to the simulations of the trees' effects on pedestrian wind comfort in the PKNU campus in views of wind comfort criteria based on the Beaufort wind force scale (BWS). We will present the trees' effects on pedestrian wind comfort in the PKNU campus in detail.
Dissolution of a single mineral grain: comparison of microfluidic experiments with pore-scale simulations
Authors: Szymczak Piotr , Dutka Filip , Starchenko Vitaliy , Osselin Florian , Magni Silvana , Ladd Anthony J.C.
Published: March 2020

We investigate the dissolution of a single grain of soluble mineral by microfluidic experiments and numerical simulations. The experiments use gypsum cylinders (10 mm radius, 0.5 mm thick) cast from rehydrated CaSO4 hemihydrate. The numerical simulations used a finite-volume discretization of the reactive-transport equations with a mesh that conforms to the evolving shape of the mineral. Using the coefficients for dilute aqueous ions, we overpredict the dissolution rate by about 25%. However, including the Debye-Huckel correction for the ion activity gives a substantial reduction in diffusion across the boundary layer at the dissolving solid surface and brings the simulation time scale into quantitative agreement with experiment.

The asymmetry introduced by the flow causes the initially cylindrical sample to take on a shape resembling one half of a figure eight, with the tip pointing in the downstream direction. The simulations give a near perfect match to the experimental size and shape. We quantify the evolution of the volume of the grain and its surface area, as well as its overall shape as the function of the Peclet number. Next we discuss the differences between the geometric surface area and the reactive surface area of a dissolving grain and explore a potential use of these results to upscale the reactive transport problem and obtain the effective reaction rates in a multi-grain system.
Tsunami scenarios for megathrust earthquakes: mechanics of multi-segment ruptures and elastic-fluid dynamics of wave propagation
Authors: Saito Tatsuhiko , Noda Akemi
Published: March 2020

Great earthquakes repeatedly occurred with different rupture processes in the Nankai trough, southwestern Japan. The 1944 Tonankai and the 1946 Nankai earthquakes (M ~8) caused serious tsunami damage over many areas along the coastline. The greatest earthquake in this region is the 1707 Hoei earthquake (M 8.4) that is believed to have ruptured the whole region (~600 km) of the Nankai Trough. The purpose of this study is to theoretically assess the tsunami height along the coasts excited by great earthquakes that can possibly occur in future in this region and simulate observable tsunami records during the earthquakes.

This study employed a new method for making various rupture scenarios. Based on a shear-stress distribution along the plate boundary estimated by the GNSS data analyses (Noda et al. 2018 JGR), we calculated coseismic slip distributions to release the accumulated stress for possible multi-segment rupture scenarios. Then, we used the strain energy released by the rupture to evaluate the possibility of each event. The released strain energy should be larger than the energy dissipated on the fault. However, for some scenarios, the released strain energy was smaller than the dissipated energy under the assumptions of friction laws. Such rupture scenarios are not likely to occur in the viewpoint of earthquake mechanics. This approach can provide necessary conditions of the strain energy or the accumulated stress levels for multi-segment rupture processes, while methods based on empirical or kinematic approaches do not treat stress or interseimsmic stress-accumulation periods required for ruptures.

Another distinctive point in our approach is that we theoretically synthesize ocean-bottom pressure changes caused by both seismic waves and tsunamis using a simulation method based on elastic and fluid dynamics (Saito and Tsushima 2016 JGR; Saito et al. 2019 Tectonophysics). Seismic wave contributions to ocean-bottom pressure changes are critically important for the synthetics in near-field or inside rupture areas because the seismic waves overlap with tsunami signals and work as noise for real-time tsunami monitoring. The records simulated in this study can be used to examine the monitoring ability of a deep-ocean observation network for megathrust earthquakes and tsunamis in this region.
Observations of ionospheric TEC peaked structures from Global Ionosphere Maps
Authors: Tsai Tsung-Che , Jhuang Hau-Kun , Lee Lou-Chuang , Ho Yi-Ying
Published: March 2020

The total electron content (TEC) data from Global Ionosphere Maps provide a global TEC map in the region between latitude 87.5°S to 87.5°N, and longitude 180°W to 180°E. The TEC data in geographic coordinates are first transformed into geomagnetic coordinates through Altitude-Adjusted Corrected Geomagnetic Model (AACGM). We then use 2-dimensional (longitudinal, 180°W-180°E and time, 10 days) Fourier transform (FT) of TEC variations along different geomagnetic latitude to obtain all wave modes in both UT (universal time) and LT (local time) frames for the period from November 18, 2002 to October 15, 2014. The summation of contributing wave modes at a given local time provides the longitudinal variation of the associated zonal waves. The phases of wave modes lead to a constructive or destructive interference of contributing zonal wave, which gives different structures at different local time. These local time structures include Weddell Sea Anomaly (WSA), Southern Atlantic Anomaly (SAA), and Four-peaked structure. The dependence of the peaked structures on latitudinal, seasonal, and solar activity is studied.
MEMS surface microgravimetry for geotechnical surveying
Authors: Du Zhijun , Mustafazade Arif , Li Yaoguo , Topham Adrian , Lofts Jeremy , Seshia Ashwin
Published: March 2020

Microgravity measurements have enabled a variety of geophysical surveying and monitoring applications including advance warning of natural hazards, slope stability monitoring, discovery of buried tunnels, pipework, and other utilities, identification of sinkholes and other natural voids, buried aquifers and in monitoring groundwater hydrology. In the civil engineering context, microgravity measurements can provide valuable information for construction projects or intervention activities by locating buried utilities, hazards or other features of relevance.

Disruptive MEMS gravity sensor technologies are poised to provide entirely new approaches for microgravity measurements in the form of portable sensors that could ultimately be mounted on remotely operated vehicles or drones, integrated into land-based distributed sensor networks, or deployed in shallow borehole configurations. Instruments based on these sensors could enable vector gravity measurements as well as full tensor gravity gradiometry.

Trials are ongoing of a single-axis MEMS surface module with a noise floor of 50 µGal/rt-Hz and a resolution of < 10 µGal while allowing for measurement over the entire +/- 1g dynamic range. This paper discusses the background and context for gravity imaging in geotechnical applications, forward modelling of case studies of relevance, and ongoing developments in the construction of a unique portable surface gravimeter.
The bivergent growth of the Cenozoic Qilian Shan, northeastern Tibetan Plateau: Insights from numerical models
Authors: Zhang Zhen , Zhang Huai , Shi Yaolin
Published: March 2020

The Qilian Shan orogenic belt, located in the northeastern margin of the Tibetan Plateau, undergoes intensive Cenozoic structural deformation with large lateral growth since the Miocene. The Cenozoic growth of the Qilian Shan is possibly resulted by the passive subduction of the North China Craton due to the far-field effect of the continuous Indo-Asian collision. Thus, the Qilian Shan can be seen as a syntectonic crustal-scale accretionary wedge above a middle intra-crustal weak layer. To date, the detailed Cenozoic crustal deformation manner of the Qilian Shan and its adjacent two basins remains unclear, especially for the southward propagation towards the Qaidam Basin. Whereas, the spatio-temporal characteristics of deformation distribution between the Qilian Shan and the adjacent two basins are critical to fulfill the lateral growth of the Tibetan Plateau. Hence, we conducted a series of high-resolution 2-D numerical models to investigate factors that influence crustal strain distribution. The first series models are thick-skinned models with single décollement, while Series II are two-décollement layer model, regarding the interaction between thick- and thin-skinned tectonics beneath the two adjacent basins. After 150 km of total convergence, model results suggest that the single décollement layer model is not sufficient in depicting the present-day crustal deformation pattern, while strain localization pattern from two-décollement layer model meets well with the geological and geophysical observations. The Hexi Corridor Basin may be involved with deep-crustal thrusting while the dominant deformation is still thin-skinned tectonics. Series III adds the filling-up sedimentation based on the conditions of Series II. We reveal that the differential sedimentation types between the Qaidam Basin and the Hexi Corridor Basin greatly depress fault propagation towards the Qaidam Basin. Note that, how deformation transfers into the Qaidam Basin remains controversial. To date, the above models still need to evolve. However, in summary, our study highlights the crustal deformation of the two margins of northeastern Tibetan Plateau is controlled by the décollements and differential sedimentation styles.
Preliminary Results of GNSS Radio Occultation Receiver onboard CSES
Authors: Xu Song , ZeRen ZhiMa , Huang JiangPing , Shen XuHui , Chu Wei , Yan Rui , Cui Jing , Lin Jian
Published: March 2020

The China Seismo-Electromagnetic Satellite (CSES) was successfully launched on February 2, 2018. Its main scientific objective is to monitor earthquake related disturbances in the ionosphere. The Global Navigation Satellite System (GNSS) Radio Occultation Receiver (GOR) on board the satellite is able to observe the occultation events of Global Positioning System (GPS) and BeiDou navigation satellite System(BDS). Compared to some conventional observation means, GOR has the advantages of low cost, high accuracy, high precision, high vertical resolution, all-weather sounding, long-term constant and global coverage. The GOR on CSES can receive about 600 ionosphere occultation events each day and 16000 each month. The strip-shaped spatial distributions of the ionospheric characteristic parameters from the GOR show that the values of NmF2 and HmF2 are larger in the areas of the equator than in middle and high latitude areas.
Spatial distribution maps of Cu, Pb, Zn, Cr, As and V in rural soils in northern part of Chile: The use of geochemical baseline values as an index in environmental assessment.
Authors: Reyes Arturo , Delgado Jose
Published: March 2020

Soil pollution is a worldwide concern and several countries are established guidelines. In the case of Chile, the very diverse soils characteristics along the country made difficult to set guidelines to acceptable levels of potentially toxic elements (PTEs) in soils. However, due to several reasons such as anthropogenic contamination, and increment of erosion rates there is urgency in to establish guidelines values to this parameters. In Chile, the most of abandoned mining wastes are located in the northern part which could negatively have impacted the ecosystem and human health. Thus, in absence of guidelines to PTEs in soils, the use of regional geochemical baseline (GBL) as a reference values could be a first approach to preliminary determine pollution levels of PTEs in soils. The objective of this study was to use the calculated GBL values to determine the influence of mining activities on the levels of PTEs in soils and to determine the spatial distribution maps of PTEs. A regional mapping of soils was conducted in northern part of Chile during 2017-2018 and the pH, electrical conductivity, redox potential and concentration of PTEs was determined. A systematic sampling in a 20,000 square-kilometer area was conducted and 467 rural top and sub soil samples were taken to determine their physical and chemical composition. The content of PTEs was determined by ICP-OES. The GBL values were estimated following the upper-whisker limit method. The pH, electrical conductivity, and redox potential of soils were 4.9-9.5, 10.5-56,000 mS/cm, and 89.7-348.3 mV, respectively. The median concentration of Mn (695.9 mgkg-1) was the highest followed by V (148.4 mgkg-1), Ni (75.2 mgkg-1), Zn (59.7 mgkg-1), Cu (59.0 mgkg-1), Sb (34.0 mgkg-1), As (18.3 mgkg-1), Cr (17.9 mgkg-1), Sn (17.5 mgkg-1), Pb (14.6 mgkg-1), Co (13.0 mgkg-1), Cd (12.9 mgkg-1), Hg (3.6 mgkg-1), and Mo (3.3 mgkg-1). The GBL for Cu, Zn, V, As, Mo, and Sb were higher than the reported average for world soils. The spatial distribution maps of Cu, Pb, Zn, Cr, As and V were used to determine pollution levels. Statistical correlation models showed the influence of either abandoned mining sites or active mining operation on the pollution levels of PTEs in the surrounding soils. The geochemical baseline values could contribute for government decision-makers to choose the best available remediation technologies for the impacted area.

 
Petrology of granitic rocks in Dan Chang District, Suphan Buri Province, Thailand
Authors: Tukpho Thirawat , Fanka Alongkot
Published: March 2020

Granitic rocks in Thailand and South East Asia have been divided into Eastern belt granite, Central belt granite, and Western belt granite.The Central belt granite widely expose in Thailand including Dan Chang area. According to the field investigation, there are two granitic bodies in Dan Chang area. The main granitic body is composed of mainly K-feldspar, plagioclase, quartz, and biotite with some accessory minerals of opaque mineral and zircon. The granitic rocks are obviously characterized by porphyritic texture of coarse-grain K-feldspar.Another granitic body is small body which is similar mineral assemblage to those granite in the main body with different proportion of K-feldspar. The amount of K-feldspar in the small body granite is less than the main body granite. However, both granitic bodies are generally characterized by porphyritic texture of K-feldspar. Moreover, aplite and pegmatite are associated with both of them. The results of field investigation and petrographic study of the granitic rocks in Dan Chang District, Suphan Buri Province, Thailand can be compared with the Central belt granite which may be resulted from the Sibumasu and Indochina collision in Late Triassic.
Shrub traits of forest and shrubland reveal different growth strategies
Authors: Ni Jian , Cao Jiayu , Yuan Quan
Published: March 2020

Shrub plants play important roles in both forest and shrubland ecosystems. Analyzing the differences of functional traits of shrubs grown in understory of forest communities and in various shrublands can explore the adaptation strategies of shrubs in different habitats. Nine functional traits of leaf and twig collected from 20 dominant shrub species in 24 plots distributed in three habitats: forest shrub layer, secondary shrubland and primary shrubland, in Beishan Mountain of Jinhua, Zhejiang Province, eastern China, were measured. The overall differences, inter- and intra-specific variations and the differences in various life forms of shrub traits in three different habitats were statistically analyzed. Results show that: 1) There are differences of nine plant traits for shrubs grown in three different habitats. The understory shrubs have larger leaf area (LA) and specific leaf area (SLA), smaller leaf dry matter content (LDMC), leaf tissue density (LTD) and twig tissue density (TTD), while shrubs in secondary shrubland have larger leaf thickness (LT) and LTD, smaller SLA and twig dry matter content (TDMC) compared with shrubs from the primary shrubland. 2) The intraspecific variation coefficients of SLA, twig diameter (TD), TTD, and TDMC in understory shrubs are the largest, while the interspecific variation coefficients of SLA, LDMC, TDMC, and TTD in ​​secondary shrubland are the smallest. 3) Among different life forms, the understory evergreen shrubs have significant higher LT, LTD, and LDMC than deciduous shrubs, while deciduous shrubs have significant higher SLA than evergreen shrubs. The differences of LT and SLA between evergreen and deciduous shrubs of primary shrubland are the same as those of understory shrubs, but the differences of LTD and LDMC between evergreen and deciduous shrubs have the opposite trend. 4) The main source affecting shrub traits is species, along with an explanation ratio from 38.01% to 78.92%. The second source is habitat. In short, compared to shrubs from shrublands, understory shrubs in forest communities form a series of trait combinations that are larger LA and SLA, smaller LTD, TTD, and LDMC to adapt to the understory environment with less light and stronger competition. Secondary shrubland, compared to the primary shrubland, has a series of shrub trait combinations that are larger LT, LTD and TD, smaller LA, SLA, TDMC and twig bark thickness (TBT) to store more nutrients.
Ecological and environmental consequences of ecological projects in the Beijing–Tianjin Sand Source Region, China
Authors: Zhao Yuanyuan , Chi Wenfeng
Published: March 2020

Evaluation of the influences of the Beijing–Tianjin Sand Source Control Project on soil wind erosion and ecosystem services is imperative for mastering the benefits and drawbacks of the program, as well as for distinguishing more reasonable estimations to evaluate regional sustainable development. Within the Beijing–Tianjin Sand Source Region, we quantified the spatiotemporal patterns of land use/cover changes (LUCCs), soil wind erosion modulus (SWEM), and essential ecosystem services throughout 2000–2015 by utilizing field investigations, remotely sensed data, meteorological data, and modeling. The influences of ecological projects on wind erosion and ecosystem services has been subsequently assessed by using those modifications brought on via the LUCCs (e.g., conversion from cropland to grassland/woodland) during the ecological construction. The results indicated that the SWEM showed a decline and ecosystem services which included carbon storage, water retention, and air quality regulation exhibited growth driven by using both local climate exchanges and human activities such as ecological projects. Excluding the effects of climate factors, the LUCCs stemming from ecological projects caused a total SWEM decrease of 3.77 million tons during 2000–2015, of which approximately 70% was prompted by the way of the transition from desert to sparse grassland. The sub-regions of desert grassland in Bayannur, Ordos Sandy Land, and Otindag Sandy Land were hot spots for wind erosion declines and ecosystem service enhancements induced by the ecological projects. We recommend that endeavors be coordinated toward the scientific management of the degraded lands and distribution of the local populace, as well as the implementation of diverse measures in the expected hotter and drier future.
Benthic foraminifera distribution and diversity in inner and outer lagoonal sediments of the UAE (United Arab Emirates)
Authors: Fiorini Flavia , Lokier Stephen W. , Ge Yuzhu , Pederson Chelsea L. , Immenhauser Adrian
Published: March 2020

Live and dead benthic foraminifera assemblages were studied from 50 samples collected in a lagoon located between Yas Island and Ras al Gurhab Island (UAE) in a system dominated by carbonate sedimentation.

Living and dead foraminifera tests are present at all of the sampled locations. The foraminifera assemblage is dominated by a high diversity of miliolidae together with epiphytic larger benthic foraminifera belonging to the genera Peneroplis, Spirolina and Sorites. Hyaline foraminifera, such as Ammonia and Elphidium, are commonly found at all the locations while agglutinated foraminifera are uncommon and have a scattered occurrence.

The abundance and diversity of benthic foraminifera were calculated for each sample. Four benthic foraminifera ecological indices were applied to the studied samples. For each of the samples we calculated: the total foraminiferal number (number of foraminifera in 1 g of sediment >125 μm); the percentages of agglutinated, porcellaneous and hyaline foraminifera tests; the ratio between living and dead benthic foraminifera; the ratio between larger benthic foraminifera with normal and abnormal test growth. The above-mentioned data have been applied to construct a foraminiferal assemblage database that facilitates the discrimination between inner and outer lagoonal environments.