bluuebunny/crossref_metadata_2025 huggingface dataset:
Improve NMR estimation of water content and distribution in unsaturated bedrocks
Authors: Zhang Fan , Zhang Chi
Published: March 2021

Nuclear magnetic resonance (NMR) has been widely used in near-surface geophysics due to its direct sensitivity to water. As a field form of NMR, borehole NMR has been applied to in situ hydrological investigations for decades. However, the recent implementations of borehole NMR to unsaturated zones face challenges due to the complex geology. Due to the fast operation speed and unsaturated conditions in critical zones, the raw NMR signals often suffer from limited relaxation time ranges and low signal to noise ratios. Such low quality of raw data can induce artifacts during inversion and following data interpretations. This study investigates the long-overdue evaluations of how the low borehole NMR data quality affects water distribution estimation in unsaturated zones. A synthetic analysis based on lab NMR data was first performed to simulate the inversion errors induced by the low-quality borehole NMR data. Lab NMR measurements were conducted on carbonate and shale samples from a well that has a corresponding borehole NMR profile. In order to match the low signal-to-noise ratio and data size of the low-quality borehole NMR data, lab NMR data points were reduced, deadtime was increased and normally distributed noise was added.  The inversion results of the synthetic data reveal that the low signal to noise ratio leads to an overestimation of signals at lower relaxation time while the limited relaxation time range does not significantly affect the total water estimation. To improve the water estimation from the low-quality borehole data, a peak decomposition and peak fusion method were then applied to the synthetic data. Relaxation time distribution of both lab and synthetic data were decomposed into multiple normally distributed peaks. The first peak with the shortest relaxation time from lab NMR was used to substitute the first peak of the synthetic borehole NMR relaxation time distribution. After peak decomposition and fusion, the predicted water contents were closer to lab NMR than original synthetic data. This study reveals the mispredictions of water distribution due to the low data quality of borehole NMR. The success of improving water content estimation on the synthetic study has clear implications that the peak decomposition and peak fusion method can be applied to actual borehole NMR data to improve water content and distribution estimation in unsaturated zones.   
Phosphorus solubilisation with varying drying and rewetting stresses under four contrasting soils from different regions of China 
Authors: Mongol Nyamdavaa
Published: March 2021

Phosphorus solubilisation with varying drying and rewetting stresses under four contrasting soils from different regions of China  

Nyamdavaa Mongol1, Jianbo Shen2, Philip M. Haygarth1  

  

1Lancaster Environment  Centre, Lancaster University, Lancaster, LA1 4YW, United Kingdom.  

2Department of Plant Nutrition, China Agriculture University, Key Laboratory of Plant-Soil Interactions, Beijing 100193, PR China  

  

Abstract 

We tested the hypothesis that agricultural soils with a recent history of drying and rewetting (DRW) can trigger phosphorus (P) solubilisation in the rhizosphere, with a subsequent growth response of maize (Zea mays). Specifically, it aimed at investigating a possible delayed effect of DRW stresses on the soils by studying the relationship between P solubilisation in the rhizosphere, plant P acquisition and performance, and root growth under different types of agricultural soils with the previous history of a series of DRW events. The soils were collected from four different agricultural regions of China, Shandong, Chongqing, Heilongjiang and Beijing (sieved <2 mm), and then treated with four varying cycles of DRW events prior to the experiment to raise levels of soil biotic and abiotic activities. A controlled pot experiment was conducted in order to establish the Olsen’s P concentration in the soil, maize shoot P concentrations, root morphology and other rhizosphere parameters, for a duration of 43 days after planting. The results show a positive relationship between plant biomass, plant P concentration and Olsen`s P. The effect was most clearly demonstrated by the level of plant growth and their biological performance in the rhizosphere, as the plants responded better in the soil with a DRW background than to a soil that did not have a history of DRW in the past. Notably, the most positive results were obtained from the Haplic Phaeozems soil of Heilongjiang, leading to an acceptance of the hypothesis. However, the soluble P concentration and plant growth response varied depending on P application rates and soil types.  

 
Lava flow modelling at El Hierro (Canary Islands): the case of Montaña Aguarijo volcano
Authors: Rodriguez-Gonzalez Alejandro , Prieto-Torrell Claudia , Aulinas Meritxell , Perez-Torrado Francisco José , Fernandez-Turiel Jose-Luis , Criado Hernández Constantino , Cabrera María del Carmen
Published: March 2021

Lava flow simulations are valuable tools for forecasting and assessing the areas that may be potentially affected by new eruptions, but also for interpreting past volcanic events and understanding the controls on lava flow behaviour. The plugin Q-LavHA v3.0 (Mossoux et al., 2016), integrated into QGIS, allows simulating the inundation probability of an a’a lava flow from one or more eruptive vents spatially distributed in a Digital Elevation Model (DEM). Q-LavHA allows running probabilistic and deterministic methods to calculate the spatial propagation and the maximum length of lava flows, considering a number of morphometric and/or thermo-rheological parameters.

El Hierro is the smallest and westernmost island of the Canary Archipelago where basaltic lava flows infer the major volcanic hazard. However, no lava flow emplacement modelling has been carried out yet on the island. Here we present Montaña Aguarijo's lava flow simulation, a monogenetic volcano located on the NW rift of El Hierro. Detailed geological fieldwork and current topographic-bathymetric data were used to reconstruct the pre-eruption (before the eruption modifies the relief) and post-eruption (at the end of the eruption, prior to erosive processes) DEMs. The obtained morphometric parameters of the lava flow (2,268m long; 5m medium thickness; 422,560m3) were used to run probabilistic (Maximum Length) and deterministic (FLOWGO) models. The latter also considers a set of thermo-rheological properties of the lava flow such as initial viscosity, phenocryst content, or vesicle proportion.

Results obtained show a high degree of overlap between the real and simulated lava flows. Therefore, the thermo-rheological parameters considered in the deterministic approach are close to the real ones that constrained Montaña Aguarijo lava flow propagation. Moreover, this work evidence the effectiveness of Q-LavHA plugin when simulating complex lava flows such as Montaña Aguarijo’s lava which runs through a coastal platform, a typical morphology of oceanic volcanic islands.     

Financial support was provided by Project LAJIAL (ref. PGC2018-101027-B-I00, MCIU/AEI/FEDER, EU). This study was carried out in the framework of the Research Consolidated Groups GEOVOL (Canary Islands Government, ULPGC) and GEOPAM (Generalitat de Catalunya, 2017 SGR 1494).

References

Mossoux, S., Saey, M., Bartolini, S., Poppe, S., Canters F., Kervyn, M. (2016). Q-LAVHA: A flexible GIS plugin to simulate lava flows. Computers & Geosciences, 97, 98-109.
Prediction of salt release from coal mine spoils at meso-scale
Authors: Jain Karan Rishabhkumar , Edraki Mansour , McIntyre Neil
Published: March 2021

Open-cut coal mining operations remove enormous quantities of overburden material inorder to access coal seam. Upon interaction with atmospheric conditions, this overburden material referred to as spoils from which salts are leached, possesses the risk of affecting surface and groundwater quality around the mine sites. Due to a distinct lack of field data on leachate rates and chemistry for full-scale spoil piles, studies have relied on geochemical testing at laboratory-scale experiments such as free-draining funnels and columns. While laboratory leaching techniques under a controlled environment are a general predictor of how spoil behaves upon weathering, there remain gaps in understanding the leachate rates taking into consideration actual particle size, flow rates, water content, temperature, and oxygen supply. This study proposes and assesses a new mesoscale approach for predicting salinity release from spoils that is designed to obtain data more relevant to the closure options under consideration. 5 coal mine spoils from 3 mines located in Queensland, Australia was sampled, characterised (physical, geochemical, and mineralogical), and were subjected to weathering at mesoscale (1-2 tonnes sample volume) leaching for 11 cycles under natural conditions. Results showed that soil-like spoils with significant pockets of less permeable clayey or silty material have the ability to retain and release solute slowly with time while rock-like spoils followed a steady decay rate. The mesoscale tests produced distinctive characteristic decay curves of salt release from typical soil-like and rock-like spoils and have been useful in the calibration of flow and moisture-dependent salt kinetic parameters. The mesocosm leaching approach developed as a part of this study was close to real-sized spoil conditions such that it mimicked the water/rock ratios, preferential flow paths, and governing solute transport processes.
Opportunities for renewable energy in regenerative development
Authors: Klain Sarah , Tango Lauren
Published: March 2021

Various philanthropic, development and agricultural organizations have begun to prioritize regenerative development, which aims to reverse ecological degradation while generating benefits, including ecosystem services, for people and biodiversity. These efforts aim to transcend sustainable development, which aims to minimize harm to the environment and human health. Here, we review the literature on ways in which renewable energy infrastructure could play important roles in regenerative development initiatives, e.g., offshore wind projects designed with artificial reef structures, photovoltaic (PV) projects accompanied with pollinator plantings, and agrivoltaics that combine crops with PV. We also identify anticipated challenges to such development, e.g., potentially larger land area requirements and higher costs than typical renewable energy development. Lastly, we provide recommendations on policies and practices that could strengthen the role of renewable energy in regenerative development.
Physical-based hydrological modelling for real-time forecasting of soil moisture in a mesoscale catchment
Authors: Shankara Mahadevan Keshav Parameshwaran , Holländer Hartmut , Bullock Paul , Frey Steven , Ojo Timi
Published: March 2021

Soil moisture is highly variable in space and time. Climate change is expected to increase the variation in precipitation that may cause more frequent extremes in soil moisture. This will have major impacts on agriculture and infrastructure. Hence, forecasting can help mitigate the impacts of soil moisture extremes by providing warning about upcoming extreme events. Accurate soil moisture forecasting will provide policymakers, farmers and other stakeholders more reliable information on crop yield potential and flood risk to improve decision making.  Real-time soil moisture monitoring and forecasting can be accomplished by utilizing a numerical modelling approach that consolidates various sources of weather and hydrological data to simulate soil moisture levels. Soil water movement is difficult to describe numerically for fine-textured soils. Additionally, soil water behaviour during freeze/thaw events are generally weakly described by numerical tools. This study addresses both problems and evaluates how soil moisture can be forecasted under the hydrologically challenging conditions of the Red River Valley using the Brunkild catchment within the Red River basin.  The Brunkild catchment represents a highly variable landscape cross-section that includes heavy clay soils of the Red River Valley through to the coarse-textured soils of the adjacent escarpment. Soil moisture levels were continuously monitored from June – August 2020 using Sentek sensors which were installed at depths of 10 to 90 cm with 10 cm spacing, and with POGO sensors that were used to manually measure surface soil moisture levels at monthly intervals from June to August 2020. Climate variables were obtained from the RISMA (Real-time In-situ Soil Monitoring for Agriculture) stations present inside the catchment.  In addition to soil moisture data, surface water flow and groundwater data will also be used to aid with calibration and validation of a fully-integrated HydroGeoSphere (HGS) surface water – groundwater model of the catchment. Preliminary results using MERRA 2 data as climate forcing showed a strong fit for all observations in sandy soils and a good fit for all observation in clay. The next simulations will use the observed weather data. The model will be recalibrated and then being used to forecast soil moisture in the Brunkild catchment for the coming 14 days for the 2021 growing season.
Epidemic compartmental models: Realizations for Covid-19 and the bearing of vaccination scenarios
Authors: Carsteanu Alin Andrei , Langousis Andreas
Published: March 2021

Our work is aimed at analyzing the intrinsic variability of epidemic compartmental models, including the main qualitative characteristics of the Covid-19 pandemic, such as a relatively long asymptomatic contagious incubation period and a time-limited immunity. Intrinsic variability is important in order to quantitatively distinguish it from extrinsic variation factors, such as variability of virulence, social behavior, weather and climate, or statistical interpretation of data. The influence of vaccination rates is also analyzed, in as far as different scenarios may avert or revert the existence of an asymptotic endemic equilibrium point, as well as contribute to the build-up of herd immunity.
Using computer vision to monitor varying water levels: an exploratory laboratory experience
Authors: Isidoro Jorge , Martins Ricardo , de Lima João
Published: March 2021

Monitoring water levels is fundamental in a variety of fields within geosciences, hydraulics, and hydrology. Examples of this can be found in the field in rivers, reservoirs, or surface runoff while, at a much lower scale, in the laboratory, e.g., open channel flow. This is an area of ​​great complexity, due to the large diversity of spatial and temporal scales of hydraulic systems and phenomena such as the non-linearity of fluid mechanics, sediment or pollutant transport, turbulence, the interactions between water and solid surfaces (natural or artificial), or atmospheric boundary conditions. The last decade has brought important advances in techniques associated with the acquisition and analysis of images, techniques encompassed in what is currently called “computer vision”.

In this work, a methodology based on image treatment and segmentation techniques was developed, which allows the detection of the free flow water surface over time in laboratory conditions using simple video equipment.

The objective of this work was to develop and validate an algorithm for detecting the free water surface with high temporal resolution. Other specific objectives were: (i) to validate the algorithm against measurements in a steady-state flow; (ii) to test the algorithm for accentuated oscillations of the free surface resulting from different bed geometries, slope, and discharge; and (iii) to assert the feasibility of the systematic use of non-specialized and inexpensive video equipment as a level measuring device, without compromising its accuracy.

All laboratory work took place at the Laboratory of Hydraulics, Water Resources and Environment of the Department of Civil Engineering of the Faculty of Sciences and Technology of the University of Coimbra. The channel has dimensions of 4.00m × 0.15m (L×W) and the slope is adjustable. Water is supplied to the channel, in a closed circuit, from a reservoir by means of a pump and piping system, and the flow controlled by a ball valve. The algorithm developed for detecting the free surface is based on the acquisition, treatment, analysis, and segmentation of images. MATLAB® was used to code functions to recognize the edges present in an image by the image intensity gradient as well as the best-defined segment present in the image, which, in this case, corresponds to the free water surface.
Episodic fluid pressure cycling controls earthquake sequences on subduction megathrusts
Authors: Dal Zilio Luca , Gerya Taras
Published: March 2021

A major goal in earthquake physics is to derive a constitutive framework for fault slip that captures the dependence of friction on lithology, sliding velocity, temperature, and pore fluid pressure. Here, we present a newly-developed two-phase flow numerical model — which couples solid rock deformation and pervasive fluid flow — to show how crustal stresses and fluid pressures within subducting megathrust evolve before and during slow slip and fast events. This unified 2D numerical framework couples inertial mechanical deformation and fluid flow by using finite difference methods, marker-in-cell technique, and poro-visco-elasto-plastic rheology. An adaptive time stepping allows the correct resolution of both long- and short-time scales, ranging from years to milliseconds during the dynamic propagation of dynamic rupture.

We investigate how permeability and its spatial distribution control the interseismic coupling along the megathrust interface, the interplay between seismic and aseismic slip, and the nucleation of large earthquakes. While a constant permeability leads to more regular seismic cycles, a depth dependent permeability contributes substantially to the development of two distinct megathrust zones: a shallow, locked seismogenic zone and a deep, narrow aseismic segment characterized by slow-slip events. Furthermore, we show that without requiring any specific friction law, our models reveal that permeability, episodic stress transfer and fluid pressure cycling control the predominant slip mode along the subduction megathrust. Furthermore, we analyze how rate dependent strength and dilatation affect rupture propagation and arrest. Our preliminary results show that fluid-solid poro-visco-elasto-plastic coupling behaves similarly to rate- and state-dependent friction. In this context, fluid pressure plays the role of state parameter whose time evolution is governed by: (i) the short-term elasto-plastic collapse of pores inside faults during the rupture (coseismic self-pressurization of faults) and (ii) the long-term pore-pressure diffusion from the faults into surrounding rocks (post- and interseismic relaxation of fluid pressure). This newly-developed numerical framework contributes to improve our understanding of the physical mechanisms underlying large megathrust earthquakes, and demonstrate that fluid play a key role in controlling the interplay between seismic and aseismic slip.
Mapping and monitoring urban landslides in New Zealand using Sentinel-1 InSAR data: A case study from Gisborne
Authors: Cook Matt , Brook Martin , Tunnicliffe Jon , Cave Murry , Hamling Ian , Holley Rachel
Published: March 2021

Landslides are widespread natural hazards that are responsible for substantial economic and societal damage globally each year. In New Zealand, landslides frequently occur on soil and rock, triggered by high rainfall, seismic activity, and land-use change and/or disturbance. This study focuses on Gisborne, a city where ongoing slope instability issues occurring across the steep slopes within the urban area are affecting several properties. Failure commonly occurs along reactivated slip surfaces, when slow-moving retrogressive slides transition into fast-moving flows during intense rainfall events. However, the extent and rate of slope deformation in the Gisborne area are poorly known. Spaceborne Interferometric synthetic aperture radar (InSAR) is a convenient method for measuring ground deformation and over the past decade, SAR systems have significantly developed and provide consistent, reliable, high-resolution global data. In particular, the launch of Sentinel-1 in 2014 marked a significant milestone, being the first civilian satellite designed explicitly for InSAR analysis, and it produces free and open access data. In this study, we illustrate the potential of InSAR to detect the slow movement of landslide deposits in Gisborne before rapid acceleration, using Sentinel-1 data. The pre-failure deformation of several previous landslides in Gisborne is measured to determine possible deformation thresholds for rapid acceleration across the urban area.
Detection of archaeological soils through portable VIS-NIR spectrometer
Authors: Choi Yoon Jung , Yu Byoungrok
Published: March 2021

Reflectance spectroscopy is widely used to rapidly and quantitatively determine soil properties. This study introduces a method to identify archaeological soils, which are soils influenced by ancient anthropogenic activities, from the surrounding landscape using a portable VIS-NIR reflectance spectrometer. To identify spectral features of archaeological soils, the method statistically calculates the difference between an archaeological soil spectrum and a non-archaeological soil spectrum. Such difference is quantified by an R-value. Any soil spectra with R-values larger than 1 are more likely to be anthropogenically-affected soils.

Previously, the method was successfully applied to several archaeological sites in Italy and Hungary showing clear differences between the archaeological and non-archaeological soils. In this study, we will investigate the R-values for soils from prehistoric settlement sites in Sintanjin, Korea, and compare these to the results from Italy and Hungary. Both in-situ and topsoil spectral measurements were gathered using a portable ASD spectrometer. In this site, soils from kitchen areas showed R-values between 2.5 and 4.2, while soils from graves ranged from 1 to 1.4. The results indicate that the R-values vary a lot depending on the type of archaeological remains and a more detailed investigation of the method to various archaeological remains is essential to improve the method. One of our interesting results is that the method can be applied to soil spectra gathered with low-resolution spectrometers which leads to the possibility of applying continuous 2D spectral imaging applications.
Reassessing the Contribution of West Antarctica to Last Interglacial Sea Level in Light of 3D Mantle Viscosity Structure
Authors: Pan Linda , Powell Evelyn M. , Latychev Konstantin , Mitrovica Jerry X. , Creveling Jessica R. , Gomez Natalya , Hoggard Mark J. , Clark Peter U.
Published: March 2021

Studies of peak global mean sea level (GMSL) during the Last Interglacial (LIG; 130-116 ka) commonly cite values ranging from ~2-5 m for the maximum contribution from grounded, marine-based sectors of the West Antarctic Ice Sheet (WAIS). However, this estimate neglects viscoelastic crustal uplift and the associated meltwater flux out of marine sectors as they are exposed, a contribution considered to be small and slowly-accumulating. This assumption should be revisited, as a range of evidence indicates that West Antarctica is underlain by shallow mantle of anomalously low viscosity. By incorporating this complex structure into a gravitationally self-consistent sea-level calculation, we find that GMSL differs substantially from previous estimates. Our results indicate that these estimates thus require a reassessment of the contribution to GMSL rise from WAIS collapse, as will ice sheet models that do not account for the uplift mechanism. This conclusion has important implications for the sea level budget not only during the LIG, but also for all previous interglacials and projections of GMSL change in the future warming world.  
Self-consistency of the regolith hypothesis for the mid-Pleistocene Transition
Authors: Drew Matthew , Tarasov Lev
Published: March 2021

Is the regolith hypothesis consistent with the physics of glacial removal of mechanically weak surface material? 

 

The  mid-Pleistocene transition (MPT) from small 40 kyr glacial cycles to large, abruptly terminating 100 kyr ones represents a major climate system reorganization for which a clear understanding is lacking. A leading mechanism for this transition is a stabilization of ice sheets due to a shift to higher friction substrate. The Pleistocene saw the removal of deformable regolith -- laying bare hard higher-friction bedrock that would help preserve regional ice during warm interstadials. This is the regolith hypothesis. 

 

The removal of regolith by Pleistocene ice sheets remains poorly constrained. To date, only models with a forced change in area of regolith cover or 1D flow line models with simplistic sediment transport have been used to probe the role of regolith in the MPT. It is therefore unclear if the appropriate amount of regolith removal can occur within the time-frame of the MPT.

 

To properly test the hypothesis, at least three components are required: capable model, observational constraint, and a probe of uncertainties. A capable model must explicitly represent relevant processes in a fully coupled self-consistent manner. We have therefore configured a state of the art 3D glacial systems model (GSM). The GSM incorporates a state-of-the-art fully coupled sediment production/transport model, subglacial hydrology, visco-elastic glacial isostatic adjustment, 3D thermomechanically coupled hybrid shallow ice/shallow shelf ice dynamics, and internal climate solution from an energy balance model. The model generates sediment by quarrying and abrasion, and both subglacial and englacial sediment transport. The subglacial hydrology model employs a linked-cavity system with a flux based switch to tunnel drainage, giving dynamic effective pressure needed for realistic sediment and sliding processes. The coupled model is driven only by prescribed atmospheric CO2 and orbitally derived insolation.

 

The required observational constraints include present-day regolith distribution and inferred Pleistocene ice volume from proxy records.

 

The final component is  a large ensemble of full Pleistocene simulations that probe both initial regolith distribution uncertainties and model parametric uncertainties. We present the results of such an ensemble, examining both rates of computed regolith removal and changes in ice volume cycling across the MPT interval.
Parameter calibration and uncertainty analysis for snow depths from the NASA Eulerian Snow On Sea Ice Model and derived sea ice thickness from ICESat-2
Authors: Cabaj Alex , Kushner Paul , Petty Alek
Published: March 2021

Snow on Arctic sea ice plays many, sometimes contrasting roles in Arctic climate feedbacks. During the sea ice growth season, the presence of snow on sea ice can enhance ice growth by increasing the sea ice albedo, or conversely, inhibit sea ice growth by insulating the ice from the cold atmosphere. Furthermore, estimates of snow depth on Arctic sea ice are also a key input for deriving sea ice thickness from altimetry measurements, such as satellite lidar altimetry measurements from ICESat-2. Due to the logistical challenges of making measurements in as remote a region as the Arctic, snow depth on Arctic sea ice is difficult to observationally constrain.

The NASA Eulerian Snow On Sea Ice Model (NESOSIM) can be used to provide snow depth and density estimates over Arctic sea ice with pan-Arctic coverage within a relatively simple framework. The latest version of NESOSIM, version 1.1, is a 2-layer model with simple representations of the processes of accumulation, wind packing, loss due to blowing snow, and redistribution due to sea ice motion. Relative to version 1.0, NESOSIM 1.1 features an extended model domain, and reanalysis snowfall input scaled to observed snowfall retrieved from CloudSat satellite radar reflectivity measurements.

In this work, we present a systematic calibration, and an accompanying estimate in the uncertainty of the free parameters in NESOSIM, targeting airborne snow radar measurements from Operation IceBridge. We further investigate uncertainties in snow depth and the resulting uncertainties in derived sea ice thickness from ICESat-2 altimetry measurements using NESOSIM snow depths.
The Relationship between the North Atlantic Oscillation and High-Wind Observations Across the Eastern United States 
Authors: Stinnett Sylvia , Durkee Joshua , Gilliland Joshua , Murley Victoria , Black Alan , Goodrich Gregory
Published: March 2021

The North Atlantic Oscillation (NAO) is a high-frequency oscillation that has known influences on the climatology of weather patterns across the eastern United States. This study explores the relationship between the daily North Atlantic Oscillation index with observed high-wind events from 391 first-order weather stations across the eastern U.S. from 1973-2015. These events were determined following typical National Weather Service high-wind criteria: sustained winds of at least 18 m•s-1 for at least 1 hour or a wind gust of at least 26 m•s-1 for any duration. Since research literature shows high-wind events are often connected to parent mid-latitude cyclone tracks, and since the NAO has been shown to influence these storm tracks, it is hypothesized that changes in NAO phases are connected to spatial shifts and frequencies in high-wind observations. Initial results show a preferred southwesterly direction during each NAO phase. Variance in high-wind directions appears to increase (decrease) during negative (positive) NAO phases. Further, the greatest spatial difference in the mean center of high-wind observations was between positive and negative NAO phases. Overall, these preliminary findings indicate changes in high-wind observations may be linked to NAO phases.
Linking Domain Repositories to Build Cyberinfrastructure for Interdisciplinary Critical Zone Research
Authors: Horsburgh Jeffery S. , Lehnert Kerstin , Bales Jerad
Published: March 2021

Critical Zone science studies the system of coupled chemical, biological, physical, and geological processes operating together across all scales to support life at the Earth's surface (Brantley et al., 2007). In 2020, the  U.S. National Science Foundation funded 10 Critical Zone Collaborative Network awards. These 5-year projects will collaboratively work to answer scientific questions relevant to understanding processes in the Critical Zone such as the effects of urbanization on Critical Zone processes; Critical Zone function in semi-arid landscapes and the role of dust in sustaining these ecosystems; processes in deep bedrock and their relationship to Critical Zone evolution; the recovery of the Critical Zone from disturbances such as fire and flooding; and changes in the coastal Critical Zone related to rising sea level. In order to support community data collection, access, and archival  for the Critical Zone Network community, the development of new cyberinfrastructure (CI) is now underway that leverages prior investments in domain-specific data repositories that are already operational and delivers data services to established communities. The goal is to create the infrastructure required for managing, curating, disseminating, and preserving data from the new network of Critical Zone Cluster projects, along with legacy datasets from the existing Critical Zone Observatory Network, including digital management of physical samples. This CI will have a distributed architecture that links existing data facilities and services, including HydroShare, EarthChem, SESAR (System for Earth Sample Registration), and eventually other systems like OpenTopography as needed, via a central CZ Hub that provides tools and services for simplified data submission, integrated data discovery and access, and links to computational resources for data analysis and visualization in support of CZ synthesis efforts. Our goal is to make data, samples, and software collected by the CZ Network Cluster projects Findable, Accessible, Interoperable, and Reusable following the FAIR guiding principles for scientific data management and stewardship, by taking advantage of existing, FAIR compliant, domain-specific data repositories. This collaboration among domain repositories to deliver integrated data services for an interdisciplinary science program will provide a template for future development of integrated interdisciplinary data services.
Full waveform inversion of the crust and upper mantle beneath the East Asia Continent and Western Pacific Subduction Zone
Authors: Xi Ziyi , Chen Min , Zhou Tong , Wang Baoshan , Kim Younghee
Published: March 2021

We present a three-dimensional transversely isotropic velocity model of the crust and upper mantle beneath the East Asia Continent and Western Pacific subduction zone based on the full waveform inversion (FWI). It minimizes waveform shape misfit between the synthetics and the observations from a large dataset, with 142 earthquakes recorded by about 2,000 broadband stations in East Asia. Compared to the previous models, the new FWI model, East Asia Radial Anisotropy Model 2020 (EARA2020) after 20 iterations shows much stronger wave speed perturbations within the imaged slabs including the Japan, Kuril, Izu-Bonin, Ryuku slabs. The high wave speed anomalies of the subducted slabs have a maximum perturbation of 8% for Vp and 13% for Vs. We have also systematically analyzed the slabs’ morphology, the intraplate tectonic structures including the North China Craton, the Sichuan Basin, and the Songliao Basin. and investigated the origin of four typical intra-continent volcanos in the continent of China including the Hainan volcano, Changbaishan volcano, Tengchong volcano, and Datong volcano.
The Impact of a Modest Anthropogenic Carbon Increase on the Carbonate Chemistry Balance of a Temperate Fjord System
Authors: Jarnikova Tereza , Ianson Debby , Allen Susan E. , Shao Andrew E. , Olson Elise M.
Published: March 2021

Coastal regions are typically characterized by considerable physical variability that in turn leads to dramatic variability in coastal carbonate chemistry.  Recent shipboard and mooring-based observations have shown large spatial and temporal variations of carbonate chemistry parameters, including air-sea CO2 flux and aragonite saturation state, in one prominent coastal region in the Northeast Pacific Ocean - the Salish Sea. The range of the observed variability in the regional carbonate system is significantly larger than the global anthropogenic change, complicating the detection of secular carbon trends. Simultaneously, sparse observations limit understanding of the carbonate balance as a whole. Here, we use a highly resolved coastal model, SalishSeaCast, to characterize the drivers of the carbonate chemistry balance of the Salish Sea, with an emphasis on air-sea CO2 flux and aragonite saturation state. We then investigate the impact of a relatively modest increase in anthropogenic carbon in this region in the context of the governing physical and biological dynamics of the system. We examine the striking effects of the anthropogenic change to date on the inorganic carbon balance of the system, highlighting impacts on the aragonite saturation state of the system and its buffering capacity, as well as suggesting some bounds for the regional air-sea and lateral carbon fluxes. We then use the GLODAP dataset of global coastal carbon observations to consider our results in the context of other regions of the Pacific Rim and the global coastal ocean. 
In-situ UV-Visible spectrometry as an alternative to determine solute concentrations at high temporal frequency in organic-rich stream waters
Authors: Pesántez Juan , Birkel Christian , Mosquera Giovanny , Peña Pablo , Arizaga Viviana , Mora Emma , McDowell William , Crespo Patricio
Published: March 2021

In-situ monitoring of the temporal variation of solutes’ (nutrients and metals) concentrations as tracers can enhance knowledge of the hydrological and biogeochemical behavior of catchments. UV-Visible spectrometry represents a relatively inexpensive and easily used tool to explore how those concentrations vary in time at high temporal frequency. However, it is not yet clear which are the best calibration methods and which solutes can be modeled with this approach. In this investigation we explored the relationship between solutes’ concentrations and wavelength absorbance in the UV-Visible range to find the best calibration method and to identify solutes that could be effectively predicted. To this end, we installed a UV–Visible spectrometer probe in a high-altitude and organic-rich tropical Andean (Páramo) stream to record the wavelength absorbance at a 5-min temporal resolution from December 2017 to March 2019. Simultaneously, we sampled stream water at 4-hour frequency for subsequent determination of solutes via ICP-MS in the laboratory. Our results show that multivariate statistical methods outperformed simpler calibration strategies to model the solutes’ concentrations that could be effectively predicted using calibration and validation datasets. Eleven out of 21 evaluated solutes (Al, DOC, Ca, Cu, K, Mg, N, Na, Rb, Si and Sr) were successfully calibrated (NSE > 0.50). This finding suggests the possibility of calibrating solutes (i.e., metals) that had not previously been calibrated through UV-Visible spectrometry in the field. Interestingly, the calibration was feasible for all solutes that presented a statistically significant correlation with dissolved organic carbon. The findings of this research provide insights into the value of in-situ operation of spectrometers to monitor water quality in organic-rich streams (e.g., peatlands). This research contributes to our understanding of aquatic ecosystems alongside assessing catchment hydrological functioning and also can enhance the protection of human water supplies.
Determining the global coherence of chorus waves in the magnetosphere
Authors: Zhang Shuai , Rae Jonathan , Watt Clare , Degeling Alexander , Tian Anmin , Shi Quanqi , Shen Xiao-Chen
Published: March 2021

Whistler mode chorus waves play a vital role in the Earth’s outer radiation belt dynamics through the cyclotron resonant pitch angle diffusion.     Recent numerical studies have shown that the temporal and spatial variability of wave growth parameters have universal importance for the diffusion process, which should be much larger than those in the traditional averaged diffusion model.       In the present study, we analyzed both the temporal and spatial coherence of chorus wave in a statistical method using data from the EMFISIS instrument onboard the Van Allen Probes A&B from November 2012 to July 2019. In total, we find 3,875 chorus wave events to calculate the correlation of wave amplitudes between Van Allen Probes A&B.      The results show that both the spatial and temporal correlation of chorus waves decrease significantly with increasing spacecraft separation and time lag, and the spatial and temporal coherence of chorus wave only last ~433 km and ~12 s. We also find that the spatial coherence of chorus waves is higher at L>6, on the dayside, or with a lower geomagnetic index (AL*), while the temporal coherence of chorus waves does not depend on the L-shell, geomagnetic index (AL*) or magnetic local time (MLT). Our results will increase the accuracy of modeling wave-particle interactions due to chorus waves.
Radiocesium-bearing microparticles cause a large variation in 137Cs concentration in the aquatic insect, Stenopsyche marmorata, in the Ota River, Fukushima, Japan
Authors: Ishii Yumiko , Miura Hikaru , Jo Jaeick , Tsuji Hideki , Saito Rie , Koarai Kazuma , Hayashi Seiji
Published: March 2021

Radiocesium-bearing microparticles (CsMPs), which are insoluble, Cs-bearing, silicate glass particles, have been found in terrestrial and freshwater environments after the TEPCO's Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in Japan. Few studies have investigated the distribution of CsMPs in freshwater ecosystems and their uptake by aquatic organisms. In this study, we determined the uptake of CsMPs by aquatic insects in the Ota River in Fukushima. Although aquatic insects are usually measured for radioactivity in bulk samples of several tens of insects, we investigated the variability of 137Cs concentration in individual aquatic insects, and the influence of CsMPs on them. Measurement of 137Cs concentrations in detritivorous caddisfly (Stenopsyche marmorata) larvae and carnivorous dragonfly larvae showed that 3 of 47 caddisfly larvae had considerably higher radioactivity, whereas no such outliers were observed in dragonfly larvae. These caddisfly larvae were confirmed to contain the CsMPs emitted from Unit 2 of the FDNPP, using a scanning electron microscope and radioactivity measurements after isolation of the CsMPs. CsMPs were also found in potential food sources of caddisfly larvae, such as periphyton and drifting particulate organic matter, indicating that larvae may ingest CsMPs along with food particles of similar size. Our study demonstrated that CsMPs could be taken up by aquatic insects and possibly by the fish consuming them. The existence of CsMPs can result in sporadic, extremely high 137Cs concentrations, and large variations in samples, and consequently obscure the actual transfer and temporal trends of 137Cs in freshwater ecosystems.
summertime stationary waves integrate tropical and extratropical impacts on tropical cyclone activity 
Authors: Wang Zhuo , Zhang Gan , Dunkerton Timothy , Jin Fei-Fei
Published: March 2021

Tropical cyclones (TC) are one of the most severe storm systems on Earth and cause significant loss of life and property upon landfall in coastal areas. A better understanding of their variability mech- anisms will help improve the TC seasonal prediction skill and mitigate the destructive impacts of the storms. Early studies focused primarily on tropical processes in regulating the variability of TC activity, while recent studies suggest also some long-range impacts of extratropical processes, such as lateral transport of dry air and potential vorticity by large-scale waves. Here we show that stationary waves in the Northern Hemisphere integrate tropical and extratropical impacts on TC activity in July through October. In particular, tropical upper-tropospheric troughs (TUTTs), as part of the summertime stationary waves, are associated with the var- iability of large-scale environmental conditions in the tropical North Atlantic and North Pacific and significantly correlated to the variability of TC activity in these basins. TUTTs are subject to the modulation of diabatic heating in various regions and are the preferred locations for extratropical Rossby wave breaking (RWB). A strong TUTT in a basin is associated with enhanced RWB and tropical−extratropical stirring in that basin, and the resultant changes in the tropical atmospheric conditions modulate TC activ- ity. In addition, the anticorrelation of TUTTs between the North Atlantic and North Pacific makes the TC activity indices over the two basins compensate each other, rendering the global TC activ- ity less variable than otherwise would be the case if TUTTs were independent.
Evidence of 8.2-ka event in Southeast Asia inferred from marginal marine sediments off Kallang River Basin, Singapore
Authors: Dixit Yama , Chua Stephen , Yan Yu Ting , Switzer Adam
Published: March 2021

The Maritime Continent (MC) is located within the Indo-Pacific Warm Pool, which is known as the largest area of warm sea surface temperatures with the highest rainfall on Earth that drives the global atmospheric and hydrologic circulation. The complex climatic system of the MC is controlled by large-scale phenomena such as the seasonal migration of the Intertropical Convergence Zone which causes the northwest and southeast monsoon circulation in the region as well as tropical Indo-Pacific climate phenomena, the Indian Ocean Dipole in the west and the El Niño-Southern Oscillation operating to the east of the MC. In addition to interactions of these climate phenomena, their influence varies across the region due to island topography and ocean–atmosphere fluxes. Despite dedicated efforts, a comprehensive picture of the impacts of abrupt climate events such as the ‘8.2 ka event’ during the Holocene on the MC has proved elusive. Here we use sedimentology and stable isotopes of benthic foraminifera collected from the marginal marine sediments off the Kallang River Basin, Singapore to reconstruct paleoenvironmental history of the early-mid Holocene. Owing to the high sedimentation rate (~4.4 mm/yr), the timing and nature of the ‘8.2 ka event’ was examined in detail in this region making this an invaluable and unique archive to study up to sub-centennial changes. Comparison of the Kallang record with other high-resolution marine and absolutely dated terrestrial archives speleothems revealed that the timing of the onset of ‘8.2 ka event’ in the western IPWP region lags the cooling in the North Atlantic and that of Asian and Indian monsoon failure, by ~100years possibly implying a north-south signal propagation. The termination of the ‘8.2 ka event’, however may have occurred near synchronously between high and low tropical regions at ~7.96ka BP possibly linked via both atmospheric and oceanic processes.

 
How does DEM error impact the optimal grid resolution of soil evolution simulation?
Authors: Liu Yangyang , Liu Jintao , Zhao Wei
Published: March 2021

The soil thickness is the key controlling factor of local hydrology and geomorphologic characteristics. The accuracy, reliability and coverage of soil thickness map are required for reliable application. Though with quite distinct structures, models for simulating soil thickness take modern topographic data (normally digital elevation model, DEM) as one of the most important inputs. Understanding the effect of grid resolution on soil thickness prediction and selecting an appropriate resolution is crucial for the macro-scale modeling. In this study, we further explored the relationship between topographic resolution and simulation accuracy of soil thickness, and propose a new method to determine the optimal simulation resolution. A series of abstract hillslopes with different terrain noise and terrain complexity were construct and different resolutions of DEM were generated. We used a simple geomorphic based model to calculate topographic index (slope, aspect and curvature) and soil thickness. The results show that the truncation error and noise of DEM will propagate during the simulation process. Furtherly, the correlation curve between DEM resolution and the simulation error of soil thickness is a hook curve. The shape of the curve is mainly controlled by two factors, terrain noise and terrain complexity. By fitting the correlation curve of all hillslopes, the curve can be predicted by them, and the resolution corresponding to the error minimum be found out, which can be called the optimal simulation resolution of the soil thickness prediction model.