bluuebunny/crossref_metadata_2025 huggingface dataset:
Geoscience data interoperability through a new lens: how designing a telescope that looks down changed our view of data.
Authors: Rawling Tim
Published: March 2020

AuScope is the national provider of research infrastructure to the earth and geospatial sciences communities in Australia. Funded through the NCRIS scheme since 2006 we have invested heavily in a diverse suite of infrastructures in that time, from VLBI telescopes to geochronology laboratories, and national geophysical data acquisitions to development of numerical simulation and inversion codes.

Each of these programs, and the communities they support have different requirements relating to data structures, data storage, compute and access and as a result there has been a tendency in the past to build bespoke discipline specific data systems.  This approach limits the opportunities for cross domain research activity and investigation.

AuScope recently released our plans to build an Australian Downward Looking Telescope (or DLT).  This will be a distributed observational, characterisation and computational infrastructure providing the capability for Australian geoscientists to image and understand the composition of the Australian Plate with unprecedented fidelity.

The recent development of an investment plan for the construction of this National Research Infrastructure has allowed our community to reassess existing data deliver strategies and architectures to bring them in line with current international best practice.

Here we present the proposed e-infrastructure that will underpin the DLT.  This FAIR data platform will facilitate open and convergent research across the geosciences and will underpin efforts currently underway to connect international research infrastructures, including EPOS, AuScope and IRIS and others, to create a global research infrastructure network for earth science.
A new method to determine both water content and hydrogen isotope composition of two forms of water in nominally anhydrous minerals
Authors: Gong Bing , Chen Ren-Xu , Zheng Yong-Fei
Published: March 2020

    A new continuous flow method, by combining high vacuum stepwise-heating (HVST) device with the thermal conversion elemental analyzer and gas isotope mass spectrometer (TC/EA-MS), is presented for determination of water contents and H isotope compositions for both structural hydroxyl and molecular water in garnet. By using the HVST device, molecular water and structural hydroxyl can be liberated step by step from garnet at different heating temperatures. By using the on-line quadrupole mass spectrometer in the HVST device, heating temperatures were determined for releasing the two forms of water from garnet from ultrahigh-pressure metamorphic eclogite in the Dabie orogen. Releasing temperatures of molecular water and structural hydroxyl from the garnet are 400°C and 1400°C, respectively. The garnet gives water of 228±39 ppm and a dD value of -110±10‰ for molecular water at dehydration temperature of 400°C for 1 hour, and water of 301±27 ppm and a dD value of -81±4‰ for structural OH at dehydration temperature of 1400°C for 1 hour. Therefore, the HVST-TC/EA-MS method can be used to analyze both water content and H isotope composition of the two forms of water in nominally anhydrous minerals.
Rhizosphere Volatile Organic Compounds: A real-time approach using diffusive soil probes on a controlled Tropical Rainforest
Authors: Gil Loaiza Juliana , Meredith Laura , Krechmer Jordan , Claflin Megan , Roscioli Rob , Shorter Joanne
Published: March 2020

Microbial metabolic functions and biogeochemical pathways of the complex rhizosphere-soil-microbe interactions change with aboveground vegetation and the ecosystem response to environmental changes. Soil trace gases and current genomic approaches have been valuable to characterize in-situ microbial activity. However, there is a lack of understanding of the complexity of the belowground processes, the time frame of microbial community responses to environmental changes and the degree to which microbial activity can be inferred current -omics approaches. In the nitrogen cycling at a field scale, microbial diversity or gene abundance sometimes does not explain N2O emissions or even gene expression, there some bacteria that cannot be cultivated, and in general –omics involve destructive soil sampling that is prone to changes of the in-situ soil conditions. Additionally, field soil sampling may not capture the heterogeneity of the soil or specific area of study.

Volatile Organic Compounds (VOCs) produced in the rhizosphere play an important role in microbial nutrient cycling. VOCs are produced by plants and microorganisms as a response to biotic or biotic stressors or the type of carbon sources available.

Here, we present how subsurface soil gas measurements in an enclosed ecosystem during the Water, Atmosphere, and Life Dynamics experiment (B2-WALD) at the Tropical Rainforest biome of Biosphere 2 (Arizona, USA) during an induced controlled drought. We present initial results of a unique non-destructive approach that simultaneously couples a) new hydrophobic-porous subsurface soil probes, b) high-resolution Tunable Infrared Laser Direct Absorption Spectrometers (TILDAS) to analyze in situ trace gas isotopomers, and c) a proton transfer reaction mass spectrometer (VOCUS, high resolution volatile organic compound gas analyzer) for VOC quantification. We measured soil gas isotopic composition of N2O and VOCs-- comparing rhizosphere and control areas before and during the drought. We will focus our discussion on VOCs and its potential as makers of microbial interactions and signaling as a response to an environmental stressor like drought.

In this project, we demonstrate the feasibility of online coupling of soil probes with high-resolution instrumentation to measure products from nitrogen cycling and nonmethane VOC production in soils as a response to soil-plant microbe interactions. In addition, this approach could be a potential tool to constraint inferences derived from different –omics approaches.
Innovative visualization and analysis capabilities to advance scientific discovery
Authors: Law Emily , Day Brian ,   Solar System Treks Project Team
Published: March 2020

NASA’s Solar System Treks program produces a suite of interactive visualization and AI/data science analysis tools. These tools enable mission planners, planetary scientists, and engineers to access geospatial data products derived from big data returned from a wide range of instruments aboard a variety of past and current missions, for a growing number of planetary bodies.

The portals provide easy-to-use tools for browse, search and the ability to overlay a growing range and large amount of value added data products. Data products can be viewed in 2D and 3D, in VR and can be easily integrated by stacking and blending together rendering optimal visualization. Data sets can be plotted and compared against each other. Standard gaming and 3D mouse controllers allow users to maneuver first-person visualizations of flying across planetary surfaces.

The portals provide a set of advanced analysis tools that employed AI and data science methods. The tools facilitate measurement and study of terrain including distance, height, and depth of surface features. They allow users to perform analyses such as lighting and local hazard assessments including slope, surface roughness and crater/boulder distribution, rockfall distribution, and surface electrostatic potential. These tools faciliate a wide range of activities including the planning, design, development, test and operations associated with lunar sortie missions; robotic (and potentially crewed) operations on the surface; planning tasks in the areas of landing site evaluation and selection; design and placement of landers and other stationary assets; design of rovers and other mobile assets; developing terrain-relative navigation (TRN) capabilities; deorbit/impact site visualization; and assessment and planning of science traverses. Additional tools useful scientific research are under development such as line of sight calculation.

Seven portals are publicly available to explore the Moon, Mars, Vesta, Ceres, Titan, IcyMoons, and Mercury with more portals in development and planning stages.

This presentation will provide an overview of the Solar System Treks and highlight its innovative visualization and analysis capabilities that advance scientific discovery.  The information system and science communities are invited to provide suggestions and requests as the development team continues to expand the portals’ tool suite to maximize scientific research.

Lastly, the authors would like to thank the Planetary Science Division of NASA’s Science Mission Directorate, NASA’s SMD Science Engagement and Partnerships, the Advanced Explorations Systems Program of NASA’s Human Exploration Operations Directorate, and the Moons to Mars Mission Directorate for their support and guidance in the development of the Solar System Treks.
Multi-point Observations of Sudden Impulses and Implications for Signal Travel Time in the Magnetosphere
Authors: Flores Erin , Chi Peter
Published: March 2020

The Earth’s magnetosphere occasionally experiences sudden movements from localized sources. For example, the impact of the interplanetary shock on the magnetosphere starts from a localized region on the dayside magnetopause, where the perturbations rapidly propagate inside the magnetosphere as the pressure front moves farther away from the Sun. The impulses generated from these sources propagate through the inhomogeneous plasma and can be detected in many corners of the magnetosphere. These impulses often mark the beginning of large-scale reconfigurations in the magnetosphere and the ionosphere, such as magnetic/ionospheric storms and substorms. The propagation of these impulses, such as that through MHD waves, is fast but not instantaneous. The propagation paths in the highly inhomogeneous magnetosphere may not be straightforward. Nonetheless, past studies have demonstrated that the impulse propagation in the dayside magnetosphere can be characterized by the Tamao model.

In this study, we examine the signatures of sudden impulses in the data from a network of spacecraft in the magnetosphere, including THEMIS, Van Allen Probes, MMS, Geotail, and GOES. The ACE and Wind data are also used for solar wind conditions. Observations from Polar, FAST, GOES, Cluster, Swarm, IMP-8, and ground-based magnetometers are also examined whenever they are available. The observations of impulse propagation time will be compared against the modeled Tamao travel time to understand how much the two agree with each other and how the comparison varies with the properties of the solar wind discontinuity.
Decadal trends in convection from satellite microwave observations of near-surface wind and deep precipitating clouds
Authors: Haddad Ziad , Hristova-Veleva Svetla , Utsumi Nobuyuki
Published: March 2020

Since the past decade, evidence derived from model reanalysis (including outgoing longwave radiation, tropopause height, the latitude where zonal mean precipitation exceeds evaporation, and the latitude where the zonal mean 500-hPa meridional streamfunction crosses from positive to negative) indicate that the tropics have been expanding since at least 1979, by a very approximate one degree per decade. To the reanalysis evidence, we have added our direct analysis of near-surface wind estimated from satellite radar scatterometty. These show a widening of the Hadley circulation, with a distinct poleward migration of the zonally-averaged crossing latitudes (from easterly trade winds in the tropics to the mid-latitude westerly winds) by about 1 degree per decade. This begs the question: are the precipitation patterns changing accordingly? The brief answer, derived from analysis of the Tropical Rainfall Measuring Mission radar data, is that deep storm top heights in the tropics showed a monotone increase over the 16-year TRMM record, but their occurrences became steadily less frequent. This will be described in more detail, along with a method to increase the sample size from the rather poor temporal sampling by the TRMM radar to a 50-fold larger sample from the microwave radiometer constellation.
Filamentary Currents in Turbulent Magnetic Reconnection
Authors: Zhou Meng , Deng Xiaohua , Zhong Zhihong , Pang Ye
Published: March 2020

Magnetic reconnection and turbulence are the two most important energy conversion phenomena in plasma physics. Magnetic reconnection and turbulence are often intertwined. For example, reconnection occurs in thin current layers formed during cascades of turbulence, while reconnection in large-scale current sheet also evolves into turbulence. How energy is dissipated and how particles are accelerated in turbulent magnetic reconnection are outstanding questions in magnetic reconnection and turbulence. Here we report MMS observations of filamentary currents in turbulent outflows in the Earth's magnetotail. We found sub-ion-scale filamentary currents in high-speed outflows that evolved into turbulent states. The normal direction of these current filaments is mainly along the XGSM direction, which is distinct from the neutral sheet. Some filamentary currents were reconnecting, thereby further dissipating the magnetic energy far from the X line. We notice that turbulent reconnection is more efficient in energizing electrons than laminar reconnection. Coherent structures composed of these filaments may be important in accelerating particles during turbulent reconnection.  
River canyon evolution governed by autogenic channel-hillslope feedbacks
Authors: Glade Rachel , Shobe Charles , Anderson Robert , Tucker Gregory
Published: March 2020

Geologists frequently debate the origin of iconic river canyons, as well as the extent to which river canyons record climatic and tectonic signals. Fluvial and hillslope processes work in concert to control canyon evolution; rivers both set the boundary conditions for adjoining hillslopes and respond to delivery of hillslope-derived sediment. But what happens when canyon walls deliver boulders that are too large for a river to carry? Large blocks of rock derived from resistant hillslope strata have recently been shown to control the evolution of hillslopes and channels by inhibiting sediment transport and bedrock erosion. Here we present Blocklab, a 2-D model within the Landlab modeling toolkit that uses a hybrid discrete-continuum framework to track block transport throughout a river canyon landscape in horizontally layered rock. Our model reveals that internal negative channel-hillslope feedbacks control erosion dynamics and result in characteristic planview and cross-sectional river canyon forms. Surprisingly, while the presence of blocks in the channel initially slows incision rates, the subsequent removal of blocks from the oversteepened channel substantially increases incision rates. This interplay between channel and hillslope dynamics results in highly variable long-term erosion rates. These autogenic feedbacks can mask external signals, such as changes in rock uplift rate, complicating the interpretation of landscape morphology and erosion histories.
Antarctic Cloud Property Retrievals from Infrared Radiances
Authors: Rowe Penny , Walden Von , Fergoda Matthew , Krill Connor , Gero Jonathon , Neshyba Steven
Published: March 2020

Clouds exert a strong radiative impact on the surface and have complicated effects that are still not well understood, particularly in the Antarctic. The amount of supercooled liquid water in Antarctic clouds, for example, is still poorly constrained, due to the low number of observations on the continent. It is also not clear how the radiative properties of supercooled liquid in those clouds should be represented in climate models. In particular, the complex refractive index (CRI) of liquid water is known to depend on temperature, but this dependence is typically ignored in climate models.

Here, we present cloud properties retrieved from Antarctic downwelling infrared radiance measurements made by an Atmospheric Emitted Radiance Interferometer (AERI) and by the Polar AERI (PAERI), using the CLoud and Atmospheric Radiation Retrieval Algorithm (CLARRA). Preliminary retrievals were made of cloud height, optical depth, thermodynamic phase, and effective radius for field experiments at Amundsen-Scott South Pole Station (2001) and at McMurdo Station (2016).

At South Pole, we find that clouds are typically thin and near the surface, in keeping with prior work. For thin clouds, the mode of the effective radii of liquid droplets (~4 μm) and ice particles (~15 μm in summer, ~12 μm in winter) at South Pole are found to be smaller than typical Arctic values (~9 μm for liquid and 17 to 25 μm for ice). Although ice cloud was found to dominate year-round at South Pole, significant supercooled liquid water was present in the summer. Cloud properties retrieved at South Pole will be compared to retrievals from McMurdo.

We further find that ignoring the temperature dependence of the CRI of supercooled liquid cloud leads to negative biases in part of the atmospheric window region (700 – 1000 cm-1), indicating underestimation of the greenhouse effect. These biases are expected to be partially offset by positive biases below 600 cm-1. Based on these considerations, we recommend using temperature-dependent CRI for infrared radiance simulations of supercooled liquid water cloud.
Estimating the configuration of the subglacial drainage system under a mountain glacier in St. Elias Mountains, Yukon
Authors: Racz Gabriela Clara , Schoof Christian , Rada Camilo , Koschitzki Robert , Haber Eldad , Flowers Gwenn
Published: March 2020

Numerous studies have documented that water at the ice-bed interface can affect ice flow dynamics of both, mountain glaciers and the Greenland ice sheet. Water at the bed is routed through a complex network of conduits that form a subglacial drainage system. The subglacial drainage system evolves over the melt season in response to the changes in the meltwater supply. However, it is challenging to study due to the inaccessibility of the glacier bed. We use an extensive near-bed water pressure data set from an ablation zone of a small, polythermal, mountain glacier in St. Elias Mountains, Yukon.  Pressure sensors, that exhibit common diurnal variations, are considered to be connected to a hydraulically active drainage system. 

We use a simplified two-dimensional continuum version of the subglacial drainage model with an additional assumption that changes in drainage configuration are negligible over a short time period. Spatially varying permeability function is used as a proxy for the subglacial drainage configuration, assuming that the areas of high (low) permeability correspond to the areas that are connected (disconnected) to a hydraulically active system.  In order to study the evolution of the subglacial drainage system over the melt season, we divide the melt season in a series of short time periods. We then use the inverse model to estimate the permeability function for each of these time periods. Continuity is ensured by using, respectively, the final pressure distribution and the estimated permeability function of the previous period, as the initial condition and the a priori estimate for the consequent time period.
Nanoscale Pb clustering and multi-domain Pb-mobility in zircon
Authors: Blum Tyler , Bonamici Chloe , Valley John
Published: March 2020

Uranium-Lead dating of zircon remains one of the most widely utilized and most reliable temporal records throughout Earth history. This stems from the mineral’s widespread occurrence, pristine zircon being both physically and chemically robust, and the ability to evaluate the presence of open system behavior (i.e. “concordance”) through comparison of the independent 238U→206Pb, 235U→207Pb, and 232Th→208Pb decay chains. The phenomenon of discordance is well documented in zircon, and is typically (though not always) associated with radiation damage accumulation and Pb-loss. Despite a long history of research, the nanoscale controls on Pb mobility and Pb loss (i.e. the relative rates of radiation damage, annealing, and Pb diffusion) remain poorly defined. The unique characterization capabilities of atom probe tomography (APT) provide a novel means to study U-Pb systematics on the scale of the radiation damage, annealing and diffusion processes. APT studies have documented nanoscale heterogeneity in trace elements, Pb, and Pb isotope ratios, and correlated the 207Pb/206Pb ratios within clusters to transient thermal episodes in the history of a zircon.

 

This work seeks to provide a foundation for multi-scale U-Pb characterization, including how differential Pb mobility at the nanoscale can influence micron- to- grain-scale U-Pb systematics. Historically, concordia diagrams have used simple Pb-loss models to extract temporal information about the timing of Pb mobility/loss; however, these models assume 207Pb and 206Pb are uniformly disturbed within a grain and lost in equal proportions at the time of Pb loss. Our previous studies suggest that radiogenic Pb can be concentrated and immobilized in nanoscale clusters, leading to differential retention of Pb in clusters vs. matrix domains, and requiring a more complex treatment of isotopic shifts during any post-clustering Pb loss. This “multi-domain element (Pb) mobility” (MDEM or MDPM) influences subsequent Pb-loss trajectories on concordia diagrams, manifesting in systematic offsets for discordia as a function of the zircon crystallization age, the timing of cluster formation, and the timing of Pb mobility. These results highlight that (1) traditional interpretations of discordia in the presence of cryptic nanoscale clustering can lead to inaccuracies, and (2) multi-scale U-Pb characterization offers a means to both study discordance and to extract additional temporal information from zircon with otherwise ambiguous and/or complex Pb-loss patterns.
Diverse Responses of Polar Mesocyclones Genesis Attributable to Orographic Forcing
Authors: Tamura Kenta , Sato Tomonori
Published: March 2020

Polar mesocyclones (PMCs) are mesoscale, maritime cyclones that occur around the high latitudes in the cold seasons. Over the northern Sea of Japan, PMC frequently occurs with cold air outbreaks from the east of the Eurasian Continent. In this study, effects of the mountains on the eastern end of the Eurasian Continent (Sikhote-Alin mountain range) on the PMCs genesis were examined by 36-years long-term numerical experiments. The sensitivity experiment, in which the Sikhote-Alin mountain range is removed, shows that the number of PMC genesis decreases and the duration between PMCs genesis and landfall becomes shorter compared with realistic experiment. These differences arise only in the southern part of the sea. This result suggests that the effect of the orographic forcing on PMC's behavior varies with the location of the PMCs genesis.
Multi-temporal analysis of radiance acquired by ASTER and Landsat 8 on Mt. Etna volcano
Authors: Musacchio Massimo , Lombardo Valerio , Romaniello Vito , Silvestri Malvina , Spinetti Claudia , Buongiorno Maria Fabrizia
Published: March 2020

Temperature estimations of active lava flows are crucial to characterize volcanic eruptions and better understand their dynamic and evolution. EO data acquired by satellites, in the SWIR-TIR spectral range, allows to retrieve active lava flows temperature applying specific algorithms (e.g. TES). In particular, radiances emitted by the High Temperature targets, acquired by multispectral space sensors, represent the input parameter for temperature estimation methods; their incertitude influences the accuracy of the temperature retrieval. In the present work, a multi-temporal analysis of radiances acquired from different spaceborne imaging sensors, at several wavelengths in the SWIR-TIR spectral range, has been carried out in order to perform a cross-comparison of data and to estimate the error associated with the radiance of high temperature targets. We considered and analysed radiance data recorded by the Advanced Spaceborne Thermal Emission and Reflectance radiometer (ASTER) and the Landsat 8 Thermal InfraRed Sensor (TIRS) on Mt. Etna volcano in the last twenty years. ASTER, launched on December 1999, is mainly used to study surface temperature and emissivity with a relatively high spatial resolution; ASTER measures radiance in the Visible and Near-InfraRed (0.52-0.86 μm) and Thermal InfraRed ranges (8.12 to 11.65 μm) with a pixel size of 15 m and 90 m, respectively, and a revisit time of 16 days. Landsat 8 is the most recent satellite of NASA Landsat program launched on February 2013. Its payload consists of two sensors: the OLI (Operational Land Imager) and the TIRS with two thermal bands. Specifically, daytime acquisitions over Mt. Etna volcano by ASTER from 2011 up to now and by Landsat 8 from 2013 up to now, are considered in the present study; the channels at 10.6 μm of both instruments are mainly investigated. The goal of the study is to analyse the migration of the thermal activity on Mt. Etna summit area.
Paleoenvironmental and paleoclimatic changes in the Japan Sea since the last glaciation
Authors: Shi Xuefa , Zou Jianjun , Gorbarenko Sergey
Published: March 2020

The Japan Sea, one of the marginal seas of the North Pacific, communicates with adjacent seas through four shallow straits (<130 m) and the present environment in the Japan Sea is mainly forced by the Tsushima Warm Current (TWC), East Asia Monsoon (EAM) and seasonal sea ice. During the Quaternary, the pronounced effects of glacial eustatic sea level on the hydrography, ocean biogeochemistry and sediment depositions in the Japan Sea over glacial-interglacial cycles. However, the spatial heterogeneity of these forcings exerting on environment of the Japan Sea may results in contrasting response. On the basis of a suite of sediment cores collected during the China-Russia joint expedition in 2010, we investigate the sedimentary processes and paleoenvironment changes in the Japan Sea. We found enhanced extent of seasonal sea-ice coverage in the western Japan Sea, which is synchronous with the intensification of East Asian Winter Monsoon (EAWM) from 15ka to 8ka. During the early last deglaciation (17ka-15ka), perennial sea ice cover at investigated site occurs and thus inhibits the deepwater formation in the Japan Sea. Since 8 ka, increased deep ventilation and dampened sea ice coverage are closely related to enhanced EAWM and invasion of high-salinity TWC into the Japan Sea. In the southern Japan Sea, the sediment provenance is mainly derived from the Yangtze and old yellow rivers, while the terrigenous matter was mainly sourced from the Yangtze River after 7 ka, on the basis of elemental and radiogenic isotopic data (Sr and Nd) of fine-sized (<63 μm) sediments. Abrupt shifts in sediment provenance occurred at ~18 ka and ~7 ka and these time periods are synchronous with changes in surface hydrography and deep ventilation in the Ulleung Basin. In the central Japan Sea, eolian dust sourced from central Asia and Chinese Loess Plateau by westerly was delivered to the central Japan Sea. In addition, deep ventilation in the southern and central Japan Sea evidenced by redox-sensitive elements and ventilation-like radiolarian species suggest intensified ventilation since 8ka and during cold spells of the last deglaciation, which is closely related to the invasion of the Tsushima Warm Current into the Japan Sea. Our data suggest that sea level is a first-order factor in controlling the environment and sediment deposition in the Japan Sea at orbital timescales, while the East Asian Monsoon and Kuroshio Current play a secondary role. Note: This study was supported by the National Natural Science Foundation of China (Grants No. 41420104005, U1606401) and National Program on Global Change and Air-Sea Interaction (GASI-GEOGE-03 &-04). 
Methane Past, Present and Future -- 250-year Methane Trend from a Fully Interactive Earth System Model Simulation
Authors: Folberth Gerd A. , Gedney Nicola , Jones Chris D. , O'Connor Fiona M. , Sellar Alistair A. , Wiltshire Andy
Published: March 2020

Methane (CH4) is the second most important anthropogenic greenhouse gas. Its Global Warming Potential over 100 years (GWP100) exceeds 28 times that of CO2. Methane surface concentrations have steadily increased since the pre-industrial due to industrialisation combined with fossil fuel use. In 1850, around the onset of heavy industrialisation in Europe and North America, the CH4 mole fraction was approximately 700 ppbv, and since then it has increased 2.5-fold to slightly more than 1830 ppbv in 2015. Fossil fuel use, raising of livestock, and cultivation of rice are the dominant contributions to the atmospheric methane burden at present with significant emissions from natural wetlands also playing a central role.

Here we present first results from the UK Earth System Model (UKESM1.0). The default release version of UKESM1.0 has been extended to represent the methane cycle fully interactively, including dynamic wetlands with global CH4, full stratospheric-tropospheric CH4 chemistry, and CH4 surface deposition. The extended configuration is capable of simulating the climate feedbacks on methane wetland emissions which are typically neglected in current Earth system models. Our simulation is driven with anthropogenic CH4 emissions from CMIP6. We conducted fully-coupled transient simulations of the atmospheric CH4 burden from 1850 to 2100 based on the historic and two future scenarios (SSP3-7.0 and SSP1-2.6) scenarios.

We compare the time series of global CH4 surface concentrations between the default CH4 concentration-driven configuration of UKESM1.0 with the fully-interactive emissions-driven configuration. Surface concentrations for the emissions-driven simulation show reasonable agreement with the concentration-driven simulation, but a low bias in the fully interactive simulation gradually emerges after about 1920 which reaches approximately -250 ppbv in the 2000s. We then present a full-cycle CH4 budget analysis based on decadal means for every 50 years between 1850 and 2100. We demonstrate that methane burden and surface mole fractions are expected to return to their 1930s values under SSP1-2.6, albeit with the natural methane sources still heavily disturbed from their original state. We also produce a detailed analysis of the contribution of wetland CH4 emissions for the 250 years of simulation.

 
Perturbations in Antarctic bottom water formation in the Atlantic sector of the Southern Ocean during the last peak interglacial period
Authors: Gottschalk Julia , Anderson Robert F. , Hasenfratz Adam P. , Hönisch Bärbel , Jaccard Samuel L. , McManus Jerry F. , Skinner Luke C. , Waelbroeck Claire , Winckler Gisela
Published: March 2020

Interglacial climate conditions are generally characterized by relatively strong and persistent deep-water formation both in the North Atlantic and in the Southern Ocean, and overall ‘stable’ climate conditions. Recent evidence, however, challenges the notion of persistent deep-water formation in both hemispheres during the last interglacial, and points at rapid reductions in convective mixing that may have lasted few centuries to millennia. The spatial pattern of this phenomenon and its driving mechanisms remain poorly constrained. Here we present multi-proxy data for rapid reductions in bottom water oxygen in the central sub-Antarctic Atlantic (sediment core MD07-3077, 44°9.20’S, 14°13.69’W, 3776 m water depth) during the warmer-than-present period of the last interglacial (i.e., 132-116 kyr before present). The first of these “stagnation events”, as they are often denoted, is synchronous, within dating uncertainties, with a similar drop in bottom water oxygenation at a more southern site, ODP Site 1094, south of the Polar Front. Our findings hint at a widespread and significant change in the formation rate and/or end-member pre-formed oxygen levels of Antarctic bottom water (AABW) in the South Atlantic during the last interglacial. The onset of these events closely coincides with increases in sea surface temperatures in the sub-Antarctic Atlantic above average Holocene levels. Although this needs to be further tested at more proximal sites, we argue that stagnation events were likely driven by excess ocean warming, in particular below ice shelves in the Weddell Sea, that may have perturbed AABW formation and/or air-sea gas exchange in that region during the last interglacial. Our findings highlight important feedback mechanisms linking hydrographic conditions at the sea surface, instabilities of the local cryosphere, and the strength of deep water formation in warmer-than-present climate scenarios – the full understanding of which has relevance for assessing the trajectory of future changes in the Southern Ocean.
Separating and characterizing functional nitrogen degraders via magnetic-nanoparticle mediated isolation technology in high concentration of ammonia nitrogen wastewater treatment
Authors: Yin Meng , Sun Yujiao , Zheng Danyang , Wang Lei , Zhao Xiaohui , Li Jie
Published: March 2020

Magnetic-nanoparticle mediated isolation (MMI) is a new method for isolating active functional microbes from complex microorganisms without substrate labeling. In this study, the composition and properties of the magnetic nanoparticles （MNPs）were characterized by a number of techniques. And then the MNPs were added to activated sludge rich in ammonia nitrogen-degrading bacteria after long-term stable treatment,  another set of experiments plus urea was set as the only carbon source in the system. Compared with the group without MNPs, degradation experiment results showed that the ammonia nitrogen degradation ability of a group of MNPs was slightly improved. The high-throughput sequencing results showed that the addition of MNPs did not change the microbial community structure of activated sludge under long-term stable conditions, and that the addition of urea as a nitrogen source significantly changed the microbial community structure. RDA analysis results also showed that Comamonadaceae_unclassified and Thiobacillus absolutely dominated in situ ammonia degradation, and the change in dominant genera showed the same trend as the degradation rate of ammonia nitrogen. It has also proved that the complex flora after adding magnetic nanoparticles is more adaptable to newly introduced pollutants, using MMI to study pollutant-degrading microorganisms under in-situ conditions has a broad application prospect.
Insights into precipitation orographic enhancement from snow-course data and their value for improved hydrologic predictions
Authors: Avanzi Francesco , Ercolani Giulia , Gabellani Simone , Cremonese Edoardo , Morra di Cella Umberto , Pogliotti Paolo , Filippa Gianluca , Ratto Sara , Stevenin Hervé
Published: March 2020

Precipitation enhancement along elevation gradients is the result of complex interactions between synoptic-circulation patterns and local topography. Since precipitation measurements at high elevation are often biased and sparse, predicting precipitation distribution in mountain regions is challenging, despite this being a key step of hydrologic-forecasting procedures and of water management in general. By acting as a natural precipitation gauge, the snowpack can provide useful information about precipitation orographic enhancement, but the information content of snow-course measurements in this regard has been generally underappreciated. We leveraged 70,000+ measurements upstream five reservoirs in Valle d’Aosta, Italy, to show how manual and radar snow courses can be used to estimate precipitation lapse rates and consequently improve predictions of hydrologic models. Snow Water Equivalent above 3000 m ASL can be more than 4-5 times cumulative seasonal precipitation below 1000 m ASL, with elevational gradients up to 1000 mm w.e. / km ASL. Enhancement factors estimated by blending precipitation-gauge and snow-course data are highly seasonal and spatially variable, with exponential or linear profiles with elevation depending on the year. Blended gauge - snow-course precipitation lapse rates can be used to infer precipitation in ungauged areas and compensate for elevation gradients in an iterative, two-step distribution procedure of precipitation based on modified Kriging. Coupling this precipitation-distribution procedure with a snow model (S3M) shows promising improvements in Snow Water Equivalent estimates at high elevations.
Strain softening of siltstones in consolidation process using a constant strain-rate loading system
Authors: Kamiya Nana , Zhang Feng , Lin Weiren
Published: March 2020

The mechanical behavior of soft rocks is dominated by the mechanical properties of the rock itself. Because soft rocks have different physical properties to hard rocks, it is essential to understand the mechanical behavior of soft rocks when tunnels and huge structures are constructed in these. Strain softening is the mechanical behavior of soil and rock materials and is important in understanding soft rock foundation. To investigate the mechanical behavior of siltstone, a sedimentary soft rock, we performed the one-dimensional consolidation tests (hereafter called K0-consolidation test) using a constant strain-rate loading system. We also took high-resolution X-ray CT images of the test specimens before and after the consolidation tests to observe the consolidation deformation. Using Quaternary siltstones distributed in the Boso Peninsula, central Japan as specimens, strain softening in the consolidation process was confirmed in some formations using two test machines at Kyoto University and Nagoya Institute of Technology.

All specimens yielded and the consolidation curves showed over- and normal-consolidation areas. Some specimens’ stress decreased suddenly at increasing strain just before yielding, which can be regarded as a real strain softening because no strain localization could be confirmed within specimens. The stress at the time of the softening differed even for specimens taken from the same formation. Furthermore, the micro-focus X-ray CT images indicated that the specimens had no macro cracks inside. This suggests that strain softening is not due to brittle failure in local areas but due to the softening of the framework structure of the siltstone itself. The samples used in this study are siltstone taken from the Quaternary forearc basin, whose development is related not only to consolidation but also tectonic effects such as horizontal compaction accompanied by plate subduction. Therefore, it is possible that the strain softening confirmed in this study reflects the micro cracks and internal structure that developed during siltstone formation.
From granulite hydration to metamorphic differentiation: Evolution of a shear zone.
Authors: Putnis Andrew , Moore Jo , Beinlich Andreas , Piazolo Sandra , Austrheim Håkon
Published: March 2020

The studied outcrop, located within the Bergen arcs of southwestern Norway, preserves the hydration of an anorthositic granulite at amphibolite-facies conditions. The amphibolite-facies hydration is expressed as both a statically hydrated amphibolite and a shear zone rock, defined by the interlayering of amphibolite with leucocratic domains. Within the outcrop, quartz-filled fractures and their associated amphibolite alteration haloes crosscut the granulite. These fractures are relicts of the initial fluid infiltration event. The fracture assemblage (quartz + plagioclase + zoisite + kyanite ± muscovite ± biotite) is equivalent to that occurring locally within leucocratic domains of the shear zone. Due to the textural and compositional similarities between quartz-filled fractures and leucocratic domains, the compositional layering of the shear zone rock may be directly linked to fracturing during initial fluid infiltration. Mass-balance calculations indicate quartz-filled fractures and compositional differentiation of the shear zone form by internal fractionation rather than partial melting or precipitation of minerals from an eternally derived fluid. This inferred fluid connectivity combined with the enhanced local dissolution indicates the presence of a continuously replenished fluid along fracture pathways. The overall conclusion is that the mass transfer processes that result in metamorphic differentiation of the shear zone lithologies are dependent on both continuous fluid flux and heterogeneous strain distribution.
Understanding the impacts of hydrograph transience on sediment transport
Authors: Phillips Colin , Lajeunesse Eric , Hill Kimberly , Paola Chris
Published: March 2020

Sediment transport is an inherently challenging process to predict due to a variety of granular and hydrodynamic phenomena. These challenges are only enhanced in natural systems where the forcing of the hydrograph and the availability of sediment is decidedly unsteady. Here we show through several field and laboratory experiments comprised of sediment flux and tracer displacement under unsteady hydrographs that their dynamics can be understood through the application of an integrated forcing metric (impulse), where the impulse represents the integrated excess transport capacity of a flood or a sequence of floods. When viewed through this framework we show that the cumulative bed load flux and tracer displacement from the particle flight length scale up to multi annual timescales are linearly related with the impulse parameter despite highly unsteady forcing. By considering the integrated forcing and sediment flux the transience of the hydrograph can be recast into a simple linear relation with parallels to long term landscape evolution models, where the details of the hydrograph are approximated as a characteristic flood stress times an intermittency factor. Through the use of an impulse metric we gain new insights that are obscured when only considering the instantaneous fluxes.
Accelerated hydrologic modeling: ParFlow GPU implementation
Authors: Hokkanen Jaro , Kraus Jiri , Herten Andreas , Pleiter Dirk , Kollet Stefan
Published: March 2020

  ParFlow is known as a numerical model that simulates the hydrologic cycle from the bedrock to the top of the plant canopy. The original codebase provides an embedded Domain-Specific Language (eDSL) for generic numerical implementations with support for supercomputer environments (distributed memory parallelism), on top of which the hydrologic numerical core has been built.
  In ParFlow, the newly developed optional GPU acceleration is built directly into the eDSL headers such that, ideally, parallelizing all loops in a single source file requires only a new header file. This is possible because the eDSL API is used for looping, allocating memory, and accessing data structures. The decision to embed GPU acceleration directly into the eDSL layer resulted in a highly productive and minimally invasive implementation.
  This eDSL implementation is based on C host language and the support for GPU acceleration is based on CUDA C++. CUDA C++ has been under intense development during the past years, and features such as Unified Memory and host-device lambdas were extensively leveraged in the ParFlow implementation in order to maximize productivity. Efficient intra- and inter-node data transfer between GPUs rests on a CUDA-aware MPI library and application side GPU-based data packing routines.
  The current, moderately optimized ParFlow GPU version runs a representative model up to 20 times faster on a node with 2 Intel Skylake processors and 4 NVIDIA V100 GPUs compared to the original version of ParFlow, where the GPUs are not used. The eDSL approach and ParFlow GPU implementation may serve as a blueprint to tackle the challenges of heterogeneous HPC hardware architectures on the path to exascale.
The mycorrhizal tragedy of the commons
Authors: Franklin Oskar , Näsholm Torgny , Henriksson Nils
Published: March 2020

The mycorrhizal tragedy of the commons

It is increasingly recognized that plant C allocation to mycorrhizal symbionts plays a critical role for plant nutrition and the future global CO2 fertilization effect on plants (Terrer et al., 2019). At the same time its future impacts are hard to predict because we do not fully understand the mechanisms underlying the symbiosis. The traditional view of mycorrhizal symbiosis always helping plants has been challenged by observations of negative effects, e.g. on tree N uptake (Näsholm et al., 2013), which makes it difficult to understand why the symbiosis has evolved and why it is so widespread.

We propose, and tested, a theory explaining the contrasting findings by showing that mycorrhizal symbiosis can be both mutualistic and parasitic at the same time. Plants and fungi are connected in a mycorrhizal network where each fungus has multiple plant partners and vice versa. Each plant can gain additional N at the expense of the other plants by supplying more C to the fungi, i.e. paying a higher C price for N. At the same time the additional C supply increases N immobilization in fungal biomass, which reduces the total N export to all plants. Thus, an individual plant can gain N at the expense of its neighbors while the negative side effects are shared among all, resulting in a tragedy of the commons effect that reduces plant N uptake and drives N immobilization in the soil.

While some observations support this hypothesis, it had not yet been thoroughly tested experimentally – until now. Based on laboratory and field experiments in boreal pine forest we tested both key components of this hypothesis - individual level mutualism and the community parasitism (decline in plant N uptake). We also estimated the strength of the fungal discrimination among its plant partners, which drives the competitive C for N trading. Finally, we highlight potential consequences of these mechanisms for boreal forest C allocation and responses to rising CO2.

References

Näsholm, T. et al., 2013. Are ectomycorrhizal fungi alleviating or aggravating nitrogen limitation of tree growth in boreal forests? New Phytologist, 198(1): 214-221.

Terrer, C. et al., 2019. Nitrogen and phosphorus constrain the CO2 fertilization of global plant biomass. Nature Climate Change, 9(9): 684-689.
Implementation of a flood forecasting system in a transboundary river basin, Peru – Ecuador
Authors: Leon Karen , Acuña Julia , Llauca Harold , Lavado Waldo , Suarez Wilson , Ordoñez Jorge , Felipe Oscar
Published: March 2020

The Peruvian Service of Meteorology and Hydrology (SENAMHI) provides hydro-climatological hazard information to population and decision-makers about flood forecasting and warning on the whole territory of Peru. For flash floods monitoring, a sub-daily simulation is critical to properly address the response of the watershed and prepare timely flash flood warnings. Over the last years, the city of Tumbes has been affected by the overflowing of Puyango-Tumbes river, which is born in Ecuador and flows to northwestern Peru. For this reason, the aim of this work is to develop an operational sub-daily hydrological forecast service for Puyango-Tumbes river basin.

To establish this forecasting system, we performed a continuous hydrological modelling approach on an hourly time scale for the Puyango-Tumbes basin at El Tigre stream gauge (4710 km2) in a semi-distributed way. We used the Sacramento Soil Moisture Accounting (SAC-SMA) model to simulate rainfall-runoff process and Saint-Venant equations for flow routing. Gridded hourly precipitation (~10 Km) was obtained by merging satellite-based precipitation estimates (IMERG-Early Run and GSMaP Near-Real-Time products) with rain-gauge data applying a simple bias adjustment. The model was calibrated and validated for the 2014/15 - 2018/19 period. Results show good agreement between observed and simulated hydrographs with Nash-Sutcliffe efficiency (NSE) between 0.6 and 0.8, for both products. For the highest floods, the peak is reasonably reached although there is an underestimation of 22% and 38% for calibration and validation period. The best performance was obtained for the SAC-SMA-IMERG scheme; however, sometimes rainfall at the upper Puyango-Tumbes is not well represented.

The flood forecasting operation will be performed on a daily-basis using an hourly meteorological forecast from ETA-SENAMHI climate model, at ~10 Km resolution. During this austral summer, the system will be evaluated and distributed to stakeholders.