bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of a multi-criteria calibration on the performances of the DREAM model
Authors: Dal Sasso Silvano Fortunato , Pizarro Alonso , Zhuang Ruodan , Zeng Yijian , Nasta Paolo , Romano Nunzio , Cebolla José Gomis , Frances Felix , Toth Brigitta , Su Zhongbo , Manfreda Salvatore
Published: March 2022

Water resources observation and modelling are essential to better understand hydrological processes and improve water resource management. However, the reliability of hydrological simulation is strongly controlled by the quality and type of field observations used for the calibration and validation processes. Therefore, it is critical to develop proper strategies for model calibration and validation in order to reduce prediction uncertainties. Standard hydrological calibration relies mainly on the time series of total streamflow at the catchment outlet; nevertheless, this leads to a limited insight into the spatial behaviour of a river basin. In this work, we use simulations from the physically-based distributed DREAM model to discuss the importance of multi-criteria calibration to obtain consistent parameter sets. The calibration methodology exploits a physical based filter to decompose the streamflow times series in two time series referring to the surface component and the baseflow. Therefore, we adopted a multi-criteria calibration procedures which optimizes: (a) the total streamflow measured at the basin outlet (used as a reference study case); b) both the surface runoff and baseflow measured at the basin outlet; and (c) the combination the time series of the two components along with the annual water balance components. In addition, we also explored the use of a lumped parametrization against a spatial parametrization derived from the soil type characteristics of the river basin. In all cases, parameter optimization was carried out using an automatic calibration performed by a genetic algorithm (GA) tool. The study was carried out for two experimental catchments located in Basilicata and Campania regions (Southern Italy). The performed experiments showed that the inclusion of physical information during the calibration process results in a general improvement of model reliability.

This research is a part of iAqueduct project funded under the Water JPI 2018 Joint Call, Closing the Water Cycle Gap – on Sustainable Management of Water Resources - Water Works 2017.
Early results from 3D full-waveform inversion imaging of the slow slip region at the shallow Hikurangi Subduction Margin
Authors: Davy Richard , Frahm Laura , Bell Rebecca , Morgan Joanna , Arai Ryuta , Bangs Nathan , Henrys Stuart , Barker Daniel
Published: March 2022

The northern Hikurangi subduction margin hosts shallow slow-slip events (SSEs) and multiple historic tsunami earthquakes. The physical mechanisms and properties of the subduction interface which enable these dual modes of fault rupture remain largely enigmatic. In 2017-2018, the NZ3D seismic experiment was conducted offshore of Gisborne to image the structure of the overriding plate and subduction interface and infer the physical properties within the region of shallow SSEs. This experiment included a 3D seismic volume collected with four 6 km long streamers, ocean-bottom seismometers, and land stations. Early results from this project have demonstrated the successful application of 2D full-waveform inversion (FWI) to high frequencies along selected seismic inlines.

Here, we present the initial results of acoustic 3D FWI on the collected streamer data. Compared with 2D FWI, 3D FWI benefits from greater azimuthal coverage and the ability to relocate out-of-plane arrivals accurately but is restricted by increased calculation times and file sizes. Velocity models reveal a complex system of thrust faulting, horst and graben structures and bottom-simulating reflectors within the accretionary prism, as well as the decollement below the accretionary prism. Velocity inversions across the imaged thrust faults in the accretionary prism indicate the presence of fluids, potentially supporting the hypothesis that the subduction interface has elevated pore-fluid pressures, which are drained along some thrust faults. Velocity inversions are also observed across bottom-simulating reflectors, which indicate the presence of gas hydrates and free gas. Imaging the shallow decollement reveals an acoustically transparent region of low velocity contrasts in the inferred location of a subducted seamount.
Simulation of Long-Term Water Erosion in Rainfed Croplands of the Eastern Washington, United States
Authors: Dahal Mugal , Wu Joan
Published: March 2022

Water erosion is an ongoing problem in eastern Washington of the United States of America due to hilly terrain, highly erodible silt loam soils, rainy winters with frequent freeze and thaw cycles that weaken the soil, and the prevalence of conventional tillage. The region is characterized by a Mediterranean-type climate with warm, dry summers and cool, wet winters comprising three distinct precipitation zones that dictate the area’s crop rotations. A unique 43-year (1940–1982) dataset of winter erosion measured on multiple agricultural fields in Whitman County, eastern Washington, showed annual erosion rates averaging 53.8 t ha−1, far exceeding the Natural Resources Conservation Service (NRCS) tolerable limit of 11 t ha−1 for the soils in the area. This annual dataset allows the comparison of field-measured erosion rates with those simulated by the WEPP (Water Erosion Prediction Project) model. The CMIP5 (Coupled Model Inter-Comparison Project Phase 5) projection suggests an increase in annual temperature of 1.1–4.7 ºC by 2041–2070 compared to 1950–1999 and a change in annual precipitation ranging from −4.7% to +13.5% in the region. Anthropogenic factors, such as tillage and crop rotation, also change with time. Conservation tillage, including reduced- and no-till, has been increasingly adopted in eastern Washington since the mid-1980s. Assessment of long-term erosion trends from past to future will help elucidate the effect of the climate-management interaction on water erosion. The specific objectives of this study are to (i) simulate long-term water erosion trends from past to present using the WEPP model and compare the results with historical field data from the cereal-grain croplands in eastern WA; and (ii) forecast erosion trends under projected future climatic and tillage conditions. Palouse River Basin, which covers nearly 80% of Whitman County, will be delineated with the outlet at Hooper Station, Palouse River. WEPP will be applied to simulate watershed hydrological and erosion processes for two different climate periods of the past to present (1940–2020) and the future (2021–2060). The historical field-measured erosion data will be used to assess WEPP performance. Climate and management conditions that lead to the largest erosion rates will be identified. Findings from this study will inform extension and aid in the continued adaption of conservation strategies in the region.
Meridional connectivity between the Labrador Sea and the subtropical AMOC
Authors: Kostov Yavor , Messias Marie-José , Mercier Herlé , Johnson Helen , Marshall David
Published: March 2022

We attempt to reconcile two seemingly conflicting paradigms regarding the north-south connectivity in the Atlantic overturning: 1) Labrador Sea buoyancy anomalies impact the subtropical Atlantic Meridional Overturning Circulation (AMOC); and 2) water mass transformation in the eastern subpolar gyre plays an overwhelmingly dominant role in AMOC variability in the subpolar regions. We thus analyze mechanisms that link the Labrador Sea with meridionally coherent adjustment in the transport along the lower limb of the AMOC throughout the North Atlantic, from the south-eastern coast of Greenland to the subtropics. The first connectivity mechanism that we identify involves a passive advection of surface buoyancy anomalies from the Labrador Sea towards the eastern subpolar gyre by the background North Atlantic Current (NAC). The second connectivity mechanism that we analyze plays a dominant role and involves a dynamical response of the NAC to surface density anomalies originating in the Labrador Sea. The adjustment of the NAC modifies its northward transport of salt and heat and affects water mass transformation in the eastern subpolar gyre. This exerts a strong positive feedback amplifying the upper ocean buoyancy anomalies that spin the subpolar gyre up or down on a timescale of several years and drive a redistribution of Lower North Atlantic Deep Water (LNADW). During the course of this subpolar adjustment, boundary-trapped waves rapidly communicate the signal to the subtropics and facilitate a meridionally coherent response in the transport of LNADW. We find evidence in the ECCO ocean state estimate that these connectivity mechanisms have affected recent historical AMOC variability.
Psychosocial response to risk mitigation measures in Iceland
Authors: Matti Stephanie , Ögmundardottír Helga , Aðalgeirsdóttir Guðfinna , Reichardt Uta
Published: March 2022

Land use planning has been espoused as a key measure to decrease the risk of climate change-relatd disasters including landslides, however there is a dearth of research on how it affects the psychosocial wellbeing of affected people. This ethnographic study examines the risk management of the Svínafellsheiði fracture in south-east Iceland, where 60 to 100 million cubic metres of debris is predicted to fall onto the glacier below, and cause flooding from or a tsunami in the proglacial lake. A no-build zone was put in place between 2018 and 2020 to prevent a further increase in the number of people exposed to the hazard. Our results indicate that the no-build zone had both direct and indirect adverse effects on the psychosocial wellbeing of those affected. It caused frustration about a perceived inability to make changes to home and businesses, people feeling that their future was in limbo or on hold, and people questioning their future in the area. These direct psychosocial effects also had the knock-on effect of causing people to talk more about the risk, thereby undermining a key coping mechanism. 

 
Mitigation and Adaptation Emissions Embedded in the Broader Climate Transition
Authors: Lesk Corey , Csala Denes , Krekeler Robin , Sgouridis Sgouris , Levesque Antoine , Mach Katharine , Horen Greenford Daniel , Matthews H. Damon , Horton Radley
Published: March 2022

Climate change necessitates an immediate and sustained global effort to reduce greenhouse gas emissions while adapting to the increased climate risks caused by historical emissions. This broader climate transition will involve mass global interventions including renewable energy deployment, coastal protection and retreat, and enhanced space cooling, which will result in CO2 emissions from energy and materials use. Yet, the magnitude of these emissions remains largely unconstrained, leaving open the potential for under-accounting of emissions and conflicts or synergies between mitigation and adaptation goals. Here, we use a suite of models to estimate the CO2 emissions embedded in the broader climate transition. For a pathway limiting warming to 2°C, we estimate that selected adaptations will emit ~1.5GtCO2 through 2100. Emissions from energy used to deploy renewable capacity are much larger at ~95GtCO2, equivalent to over two years of current global emissions and ~8% of the remaining carbon budget for 2°C. These embedded transition emissions are reduced by 80% to 20GtCO2 under a rapid decarbonization scenario limiting warming to 1.5°C. However, they roughly double to 185GtCO2 under a low-ambition transition consistent with current policies (2.7°C warming by 2100), mainly because a slower transition relies more on fossil fuels. Under this status-quo, the emissions embedded in the transition total nearly half the remaining carbon budget for 1.5°C. Our results provide the first holistic assessment of the carbon emissions embedded in the transition itself, and suggest that these emissions can be largely minimized through rapid energy decarbonization, an underappreciated benefit of enhanced climate ambition.  
The Bassa Nera pond (Central Pyrenees), a potential sentinel of climatic changes over the last 15,000 years.
Authors: Blasco Arnau , Calero Miguel Angel , Rull Valentí , Cañellas-Boltà Núria , Garcés Sandra , Montoya Encarnación , Vegas-Vilarrúbia Teresa
Published: March 2022

Over the last decades, significant increases in temperature and in the incidence of extreme climatic events have been registered in the Iberian Peninsula. Environmental changes  are easily recorded in high mountain lakes, due to their sensitivity and isolated location. Since paleolimnological information can be very useful for planning and modelling future climate change scenarios, it is necessary to find suitable lakes and test their sensitivity to current and past climatic shifts in order to adequately fulfill these tasks.

In order to test the suitability of the Bassa Nera pond as an indicator of global climatic change, this study aims to examine the variations of different  paleoindicators over the last 15,000 years. The variations of paleoenvironmental data can be then compared with the changes of different biological indicators (chironomids, diatoms, pollen), to find likely correlations that can be used to figure out future climatic scenarios and to provide information for environmental management.

For this study, a core of approximately 1,100 cm was extracted (PATAM 12-A-14) and dated with radiometric techniques. Sedimentological analysis was performed by applying conventional stratigraphic techniques and X-ray fluorescence methods. The variability of the sedimentary sequence allowed us to reconstruct the different climatic events. The pond recorded a long sedimentary sequence encompassing the last 15,000 years. The sedimentological analysis allowed us to establish 5 different stratigraphic units which we have separated in two principal sections. The first section is formed by organic rich facies while the remains of the core is composed mainly of clays and silts facies with some sand layers.

These data will be very useful to establish which and how past climatic events have affected this high mountain basin, when reconstructing the evolution of main paleolimnological indicators of environmental change. And in conjunction with subsequent studies, it will establish whether or not the suitability of the Bassa Nera as a sentinel of climatic global change. This in turn will allow the  establishment of a network of sentinel lakes in the Iberian Peninsula.
A push-pull kinetic interface-sensitive tracer method to quantify the fluid-fluid interfacial area in dynamic two-phase flow in porous media
Authors: Gao Huhao , Tatomir Alexandru , Abdullah Hiwa , Sauter Martin
Published: March 2022

The kinetic interface-sensitive (KIS) tracer, relying on a zero-order reaction on the fluid-fluid interface, is a newly developed method to measure the fluid-fluid interfacial area (FIFA) in drainage processes. The concentration of the reaction product, obtained by measuring the water samples after the breakthrough, is interpolated with numerical model to determine the FIFA. However, a major limitation of the previous method is that the volume of available water sample is highly dependent on the sand type and the system parameters, and the measurement is not applicable when the water sample is not sufficient. An alternative is to apply the KIS tracer in the “push-pull” test, meaning the drainage process is followed by an imbibition process with the flow direction reversed. This study applies the pore-scale numerical simulation and the column experiment to study the KIS tracer reactive transport during a push-pull test. The breakthrough curve of the product concentration is interpolated with both macro-scale numerical model and a modified analytical solution for the push-pull process. It is found the shapes of the concentration breakthrough curves from the pore-scale simulations and the column experiments are fit, showing a non-linear descending trend with respect to time. The KIS tracer reactive transport process in the push-pull test and the validation of the measured FIFA from the concentration breakthrough curve, are demonstrated based on the pore-scale simulation results. Finally, for the (n-octane/water) displacement process in the column packed with the glass beads with diameter of 240 μm (at the capillary number of 5×10-7), the FIFA is measured 210 m-1 at the water saturation of 0.33, which is consistent with some literature data.

 
Decadal Sea Level Variability in the Tropical Atlantic
Authors: Kemgang Ghomsi Franck Eitel , Pappukutty Raj Roshin , Rouault Mathieu
Published: March 2022

This study examines sea level change in the context of decadal-scale variability in the ocean-atmosphere dynamics of the tropical Atlantic. This time scale is of great significance for adaptation and mitigation in the context of increasing societal threats from the ongoing harmful effects of anthropogenic climate change. Decadal climate variability in the Atlantic is caused by the interaction of the gyres and is evidenced by persistent multi-year anomalies in sea surface temperature, heat content and thermocline depth (through steric sea level and dynamic height). In this study, the tropical sea level anomaly (SLA) was decomposed into interannual and decadal time scales via an empirical orthogonal function (EOF) method. The SLA variability was investigated and found to be closely related to climatic variability patterns. In addition, decadal SLA variabilities were observed between 1993 and 2016, with SLA and SLP seasonal shifts occurring in the second decade, with no change in the equatorial wind stress, responsible for warm events.
A transient glacial cycle simulation with the coupled CESM1.2-PSUIM climate-ice-sheet model
Authors: Yun Kyung-Sook , Timmermann Axel
Published: March 2022

Here we present first results from a series of transient glacial cycle simulations which were conducted with the Community Earth System model (CESM, version 1.2) coupled to the Penn State University ice sheet-ice-shelf Model (PSUIM). The coupling is achieved by applying CESM-simulated surface air temperature, precipitation, surface shortwave radiation and subsurface-ocean temperatures to the PSUIM. CESM is forced in return by PSUIM-simulated ice sheet cover, topography, and freshwater fluxes. The coupled model, which uses a ~ 4 degree horizontal resolution in the atmosphere and ocean and ~ 40 km for the ice-sheets in both hemispheres, includes representations of the lapse-rate, desert-elevation and albedo-dust feedbacks. The coupled model, which uses moderate bias corrections for temperature and precipitation, reproduces the ice sheet evolution over the last glacial cycle in reasonable agreement with paleo-climate data. In this presentation we will further highlight the sensitivity of simulated glacial variability to changes in key surface parameters as well to the individual orbital and greenhouse gas forcings. Our results reveal that only the combination of orbital and CO2 forcings can generate the full glacial/interglacial amplitude. Single forcings are insufficient to generate glacial variability, which emphasizes the need to understand the mechanisms that led to the orbital pace-making of CO2 during the Pleistocene.
How various surface covers affect soil structure and hydraulic properties
Authors: Fér Miroslav , Nikodem Antonín , Klement Aleš , Kodešová Radka
Published: March 2022

Different land uses significantly affect the soil water and temperature regimes. Very different modifications of the soil surface are found especially in the urban environment, where different materials, which are used in gardening and civil engineering, are used to cover soil surface. Alternations of these regimes due to modifications of soil covers may lead to changes in soil properties. Therefore, the goal of this study was to find out how soil properties, particularly soil structure and soil hydraulic properties changed during our experiment, which has been mainly focused on the monitoring of soil water and thermal regimes under five different surface covers (bare soil, bark chips, concrete, mown grass, and unmown grass). The surface of a Haplic Chernozem (which was originally coverd by grass) was modified in the autumn 2012. Since then, climatic conditions are monitored, and soil water contents and temperatures are measured at the depths of 10, 20, 30, 40, 60, and 80 cm. In the summer 2020, after removal of the surface over, intact soil samples were taken, on which the hydraulic properties were measured using the multistep outflow method. Another set of the undisturbed soil samples was used to study soil structure using the X-Ray computer tomography. In addition, these samples were next used to prepare thin soil slides for micromorphological analyses. Along with soil sampling, the measurement of some characteristics took place directly in the field. The mini disk tension infiltrometer with a disk radius of 2.22 cm was used to measure unsaturated hydraulic conductivities for pressure head of –2 cm. The net CO2 and net H2O efflux were measured using the LCi-SD portable photosynthesis system with a Soil Respiration Chamber. The CT and micromorphological analyzes showed that while the soil under the bare surface showed small aggregates and small interaggregate pores, the soil under the grass cover was formed by large aggregates with large pores formed by roots and organisms living in soils. Soil structure under concrete or bark chips was compact with thin fractures and few pores created by organisms living in soils. However, porosity under bark chips was larger than that under concrete likely due to better conditions, i.e., larger amount of the organic matter content due to the decomposition of organic mulch. Measured soil properties reflected character of soil structure.

Acknowledgement: Study was supported by the European Structural and Investment Funds, projects NutRisk (No. CZ.02.1.01/0.0/0.0/16_019/0000845).  
Shear-margin melting causes stronger transient ice discharge than ice-stream melting according to idealized simulations
Authors: Feldmann Johannes , Reese Ronja , Winkelmann Ricarda , Levermann Anders
Published: March 2022

Basal ice-shelf melting is the key driver of Antarctica’s increasing sea-level contribution. In diminishing the buttressing force of the ice shelves that fringe the ice sheet the melting increases the solid-ice discharge into the ocean. Here we contrast the influence of basal melting in two different ice-shelf regions on the time-dependent response of an idealized, inherently buttressed ice-sheet-shelf system. Carrying out three-dimensional numerical simulations, the basal-melt perturbations are applied close to the grounding line in the ice-shelf’s 1) ice-stream region, where the ice shelf is fed by the fastest ice masses that stream through the upstream bed trough and 2) shear margins, where the ice flow is slower. The results show that melting below one or both of the shear margins can cause a decadal to centennial increase in ice discharge that is more than twice as large compared to a similar perturbation in the ice-stream region. We attribute this to the fact that melt-induced ice-shelf thinning in the central grounding-line region is attenuated very effectively by the fast flow of the central ice stream. In contrast, the much slower ice dynamics in the lateral shear margins of the ice shelf facilitate sustained ice-shelf thinning and thereby foster buttressing reduction. Regardless of the melt location, a higher melt concentration toward the grounding line generally goes along with a stronger response. Our results highlight the vulnerability of outlet glaciers to basal melting in stagnant, buttressing-relevant ice-shelf regions, a mechanism that may gain importance under future global warming.
Flood flow modelling coupled with ML-based land cover detection from UAV and satellite river imagery
Authors: Sato Takuya , Iwami Shuji , Miyamoto Hitoshi
Published: March 2022

This research examined a new method for coupling flood flow modelling with the machine learning (ML)-based land cover detection from the Unmanned Aerial Vehicle (UAV) and satellite river imagery. We examined a 2 km river channel section with a gravel bed in the Kurobe River, Japan. The method used Random Forests (RF) for riverine land cover detection with the satellite images' RGBs and Near InfraRed (NIRs). In the process, the UAV images were used effectively to train the RF in several small portions of the river channel where the types of riverine land cover were precise. Using these UAV images with the corresponding feature values (i.e., RGBs and NIRs) of the satellite images made it possible to create the training data with high accuracy for land cover detection. The results indicated that combining the high- and low-resolution images in the RF could effectively detect waters, gravel/sand, trees, and grasses from the satellite images with a certain degree of accuracy. Its F-measure, consisting of precision and recall rates, had high enough with 0.8. Then, the ML-based land covers were coupled with a flood flow model. In the coupling, the results of the detected riverine land covers were converted into the roughness coefficients of the two-dimensional flood flow analysis. The flood flow simulation could reproduce the velocity field and water surface profile of flood flows with high accuracy. These results strongly suggest the effectiveness of coupling the current flood flow modelling with the ML-based land cover detection for grasping the most vulnerable portions in river flood management.
Land-atmosphere coupling speeds up flash drought over South China in a changing climate
Authors: Wang Yumiao , Yuan Xing
Published: March 2022

Flash drought is a new type of drought with rapid onset, which occurred frequently in recent years over the world. Compared with the traditional drought, the rapid onset makes it difficult to predict in time, and it poses a serious threat to agriculture and ecosystem. However, causes of the rapid onset and underlying mechanisms are still unclear. Considering that the land-atmosphere coupling can regulate the evolution of extreme drought, here we investigate the coupling characteristics during flash droughts over South China, and carry out the attribution by using the latest Coupled Model Intercomparison Project Phase 6 (CMIP6) model simulations. Through the synthetic analysis of flash drought onset, it is found that extreme precipitation deficit and strong evapotranspiration provide favorable conditions for flash drought onset, and the dry coupling between land and atmosphere further aggravates the decline in soil moisture, and increases the onset speed. In addition, with the increase of onset speed, the contribution of evapotranspiration increases accordingly, and the dry coupling between land and atmosphere further dominates the evolution. This suggests that the land-atmosphere coupling plays a key role in increasing the onset speed of flash drought. Furthermore, the impact of climate change on the onset speed of flash drought also can’t be ignored. The results of detect and attribution show that anthropogenic climate change (caused by the emissions of greenhouse gases and aerosols, etc) has increased the likelihood of flash drought onset speed over South China in 2019 by 24±16%, which is closely related to anthropogenically increased evapotranspiration.
Nature of Deep Earthquakes in the Pacific Plate from Unsupervised Machine Learning
Authors: Mao Gilbert , Ferrand Thomas , Li Jiaqi , Zhu Brian , Xi Ziyi , Chen Min
Published: March 2022

Deep earthquakes, 300 to 700 km deep, have been observed for decades and shown to originate from major mineral transformations occurring at these depths, including phase transitions of olivine and pyroxenes. Yet, we still do not fully grasp their mechanism. Although transformational faulting in the rim of the metastable olivine wedge (MOW) is hypothesized as a triggering mechanism of deep-focus earthquakes, there is no direct seismic evidence of such rim. Variations of b-value – slope of the Gutenberg-Richter distribution – have been used to decipher triggering and rupture mechanisms of earthquakes. However, regarding deep-focus earthquakes the detection limit prevents full understanding of rupture nucleation at all sizes.

With one of the most complete catalogs, the Japan Meteorological Agency (JMA) catalog, we estimate the b values of deep-focus earthquakes (> 300 km) of four clusters in the NW Pacific Plate based on unsupervised machine learning. The applied K-means, Spectral and Gaussian Mixture Models Clustering algorithms divide the events into four clusters. For the first time, we observe kinks in the b values with abrupt reductions from 1.5–1.8 down to 0.7–1.0 at a threshold Mw of 3.7–3.8 for the Honshu and Izu clusters, while normal constant b values (0.9–1.0) are observed for the Bonin and Kuril clusters.

The four clusters found by the algorithms actually correspond to events within four different segments of the sinking Pacific lithosphere, characterized by significant differences in hydration state prior to subduction. High b values (1.5–1.8) at low magnitudes (Mw < 3.7–3.8) correlate with highly hydrated slab portions. The hydrous defects would enhance the nucleation of small earthquakes via transformational faulting within the rim. Such mechanism operates for small events with a rupture length of less than 1 km, which would correspond to the thickness of the MOW rim.

Combining with the b-value analysis from the latest CMT catalog, the kink at Mw 6.7 suggests that the thermal runaway mechanism operates for larger earthquakes rupturing through and possibly propagating outside the MOW, with increased heterogeneity in the new rupture domain. The changes of controlling mechanism and rupture domain heterogeneity due to the slab hydrous state and thermal state can explain the spatially varying b values.
Fractional Crystallization Of The Basal Magma Ocean: Consequences For Present-day Mantle Structure
Authors: Ismail Mohamed , Ballmer Maxim
Published: March 2022

      The crystallization of the Basal Magma Ocean (BMO) sets the stage for the long-term evolution of terrestrial planets and may leave behind large-scale thermochemical structures in the lower mantle. Previous work shows that a FeO-enriched molten layer or basal magma ocean (BMO) is stabilized at the core-mantle boundary of large rocky planets such as Earth for a few billion years. The BMO itself is expected to freeze by fractional crystallization (FC) because it cools very slowly. However, the fate of BMO cumulates has not yet been systemically explored.

To explore the fate of the BMO cumulates in the convecting mantle, we explore 2D geodynamic models with a moving-boundary approach. Flow in the mantle is explicitly solved, but the thermal evolution and related crystallization of the successively crystallizing BMO (i.e., below the moving boundary) are fully parameterized. The composition of the crystallizing cumulates is self-consistently calculated in the FeO-MgO-SiO2 ternary system according to Boukaré et al. (2015). In some cases, we also consider the effects of Al2O3 on the cumulate density profile. We then investigate the entrainment and mixing of BMO cumulates by solid-state mantle convection over billions of years as a function of BMO initial composition and volume, BMO crystallization timescales, distribution of internal heat sources, and mantle rheological parameters (Rayleigh Number and activation energy). We vary the initial composition of BMO by manipulating the bulk molar fraction of FeO, MgO, and SiO2, e.g. considering BMO compositions such as pyrolite, lower-mantle partial melts of pyrolite (after 50% batch crystallization), or Archean Basalt.

For all our model cases, we find that most of the cumulates (first ~90% by mass) are efficiently entrained and mixed through the mantle. However, the final ~9% of the cumulates are too dense to be entrained (either fully or partially) over the age of the Earth, and rather remain at the base of the mantle as a strongly FeO-enriched solid layer. Unless the initial thickness of the BMO is ≤100 km, this strongly enriched and intrinsically dense layer should cover the CMB globally. We highlight that this outcome of BMO fractional crystallization is inconsistent with the geophysical constraints. Our results suggest that the BMO was either very small initially or did not crystallize by end-member FC. An alternative mode of crystallization may be driven by an efficient reaction between a highly-enriched last-stage BMO with the overlying mantle. Such reactive crystallization may be much faster than FC of the BMO, as it is driven by chemical disequilibrium instead of (slow) planetary cooling.
Frontiers in quantitative paleogeography and paleomagnetism
Authors: Domeier Mat , Arnould Maëlis , Eyster Athena , Gallo Leandro C. , Gürer Derya , Király Ágnes , Robert Boris , Rolf Tobias , Sapienza Facundo , Shephard Grace E. , Swanson-Hysell Nick , Vaes Bram , van der Boon Annique , Wu Lei , Zhang Yiming
Published: March 2022

The last few years have been marked by a number of motivating novel ideas and methodological advancements in paleomagnetic analysis (e.g. trans-hierarchical uncertainty propagation), observational and theoretical geodynamics, and paleogeographical modeling (e.g. optimisation and Bayesian approaches). Many of these developments offer new insights on, and/or approaches to estimating, the past motions of tectonic plates—but so far these developments have largely unfolded in isolation of one another. In November 2021 an international group of 15 young scientists with highly complementary backgrounds (spanning the aforementioned fields) gathered to explore and discuss these exciting new developments and to brainstorm strategies that may enable their integration. We anticipate that the integration of these diverse new ideas and methods will open new frontiers in plate tectonic research, and notably lead to much better-constrained paleogeographic models. In this presentation, we will share some of the insights and strategies that emerged from the workshop, including the advantages of conducting paleomagnetic analysis at the site-level, the application of emerging paleomagnetic Euler pole analysis frameworks, and the use of insights extracted from Earth-like geodynamic models (which self-generate plate tectonic behavior) to further constrain the results of these paleomagnetic methods. We also present some preliminary results of early experiments putting these strategies into practice on a paleomagnetic dataset from North America.  
A framework for smart assessment of river health using machine learning
Authors: Enriquez Brambila Enya Roseli , Corzo Perez Gerald , McClain Michael , Solomatine Dimitri
Published: March 2022

There is a current concern for the health of river ecosystems due to their vulnerability and increasing deterioration from human pressures, as well as the interest in achieving freshwater environmental sustainability in the well-known climate change challenges.

Analysis of international monitoring frameworks of river health have highlighted the need to increase data availability and frequency as well as reduce data uncertainty. With this, new aggregation, standardization, and classification methods are required as the development of technologies have grown and reached citizens at different social and cultural levels, their participation have increased in the recent years, showing important time-cost advantages. However, still there are no clear protocols to implement as assessment using mobile phone tools and platforms. 

This study aims to develop a dynamic framework for smart river health ecosystem monitoring, employing citizen science and remote sensing. This concept uses hydro-morphological and biological river indicators, combined with machine learning algorithms to analyze spatiotemporal data. 

The smart framework for assessment presented here aims to be provide to 1) Characterized  natural and non-natural changes of river ecosystem health; 2) Improve river monitoring methods linking local observation and remote sensing data; 3) Develop databases and data visualization of river condition components; 4) Enable citizens to become a large sensor network to contribute to river health monitoring; and 5) Determine and georeferenced the causes of  river health changes to support nature-based solutions for river ecosystem management.
Methane and Environmental Impacts of Abandoned Oil And Gas Wells in the North American Arctic-Boreal Region
Authors: Klotz Louise Anne , Sonnentag Oliver , Kang Mary
Published: March 2022

Arctic and Boreal regions are experiencing major natural and anthropogenic disturbances, leading to significant changes in ecosystem composition, structure and functioning in recent decades. Therefore, it is crucial to understand the main drivers of change, as well as the ecosystem impacts on natural and cultural resources, human health and the climate system. Large numbers of oil and natural gas wells are being drilled in Arctic and Boreal regions; however, the number and distribution of wells drilled in these regions over time is not well documented and understood. Moreover methane emissions and relationship with land cover and land cover change have not been analyzed. Using oil and gas well databases from provincial, territorial and state agencies in Canada and the U.S., we analyze drilled oil and gas wells throughout the study period (1984-2014) and in relation to land cover distribution and change across the Arctic-Boreal region of western North America. We find 254,998 wells, mostly located in Alberta (211,747) and British Columbia (35,012), in Arctic and Boreal regions of Canada and the U.S. We characterize the wells, based on data provided in the database, according to well production type (gas or oil and gas) and well abandonment status (active, abandoned, abandoned and plugged) and find that annual well drilling has increased from 269 to 8599 from 1984 to 2014. We estimate emissions from abandoned oil and gas wells in the study domain to be 40 – 148% of Environment and Climate Change Canada’s national estimate for methane emissions from abandoned oil and gas wells in 2018. Finally, using the annual land cover maps for 1984-2014, we find the number of drilled wells in each land cover class throughout the years. We identify significant increases in number of wells drilled between 1984-1999 and 2000-2014 in evergreen forest, sparsely vegetated and barren land cover classes. 
Erionite in New Zealand: initial assessment and characterization
Authors: Patel Janki , Brook Martin , Di Giuseppe Dario , Scognamiglio Valentina , Gualtieri Alessandro F. , Kah Melanie , Hamilton Ayrton
Published: March 2022

Erionite is a naturally occurring zeolite mineral originating from diagenesis or hydrothermal alteration of volcanic rocks. Typically, the two main types of rock in which erionite occurs are tuff and basalt. Erionite generally displays a fibrous morphology, and as with asbestos fiber exposure, when it is aerosolized and inhaled, fibrous erionite has been linked to cases of malignant mesothelioma, a fatal and aggressive tumor. Importantly, fibrous erionite appears to be similar or even more carcinogenic than the six regulated asbestos minerals. The first health issues regarding erionite exposure and mesothelioma were noted in Cappadocia (Turkey), and more recently, occupational exposure issues have emerged in the USA. The International Agency for Research on Cancer (IARC) has classified erionite as a Group 1 carcinogen. Nevertheless, when erionite fibers remain undisturbed in rock and/or, they are not thought to pose a risk to human health. In New Zealand, erionite has been found in surface rock exposures at numerous locations throughout both the North and South Islands, including (from north to south) Kaipara, Auckland, Taupo Volcanic Zone, Banks Peninsula, and the Moeraki coast. New Zealand is one of a number of high-income countries with elevated incidence of malignant mesothelioma (2.6 per 100,000), thought to result from occupational exposure to airborne asbestos fibers. However, recently people with no known asbestos exposure history have presented with mesothelioma. Thus, understanding the distribution and character of erionite in New Zealand may be important, as residential land development is occurring in some areas where erionite is known to be present. As an example case study, during an investigation at Auckland on the North Island, Miocene tuffaceous rocks from the Waitemata Group were studied using a range of analytical techniques, including SEM, TEM, Raman Spectroscopy, XRPD and FT-IR Spectroscopy. The preliminary investigation revealed that erionite-K was present within surface rock exposures, and exhibited a fibrous morphology. Dimensional analysis indicated just under half of the fibrous minerals satisfied the requirements for a respirable airborne fiber (length, L ≥5μm, a diameter, w ≤3μm, and L/w value ≥3:1). Research is ongoing in New Zealand into: (1) improved delineation of erionite geological occurrence, (2) mineralogical and chemical characterization, and, (3) transport pathways in rock and soil, all of which will contribute to future risk assessment.

 
A machine-learning model to predict uncertainty in permafrost thaw-induced land cover transition 
Authors: Akbarpour Safsari Shaghayegh , Craig James
Published: March 2022

This study addresses the effects  of  future  climate-induced permafrost thaw  on  the distribution of land cover in the discontinuous permafrost zones of Northwest Territories (NWT) of Canada. The rapid transition from  a landscape dominated by peat plateaus to one dominated by connected wetlands (fens) and isolated wetlands (bogs) is intricately connected to permafrost thaw. To be able to predict and estimate the potential long-term evolution of these three dominant land covers, we developed a machine learning-based time series land cover change model (TSLCM). The TSLCM is trained on a set of spatio-temporal variables as driving factors of change including: the estimated summertime land surface temperature anomaly (LST), the distance to land cover interfaces, time intervals between observations, time-accumulated land surface temperature, and classified land cover maps from 1970-2008. The TSLCM is used to capture  spatial patterns of change, replicate historical land cover change, and generate reasonable estimates of future land cover evolution over time. The output of TSLCM model is the spatial distribution of fen, bogs, and peat plateaus consistent with a default 50\%\ threshold applied on the predicted probability maps. 
We here use the TSLCM to simulate land cover change under multiple plausible futures scenarios by using the most recent set of climate model projections. The simulation of the TSLCM under different scenarios helps us to:

    1: visualize the spatial pattern of change
    2: calculate the pace of evolution over time and compare results between climate scenarios
    3:  explore the sensitivity of the model to driving factors of change

 
In addition to examining uncertainty due to climate uncertainty, a probabilistic approach is used to sample the threshold value to generate a range of land cover realizations. 
Analysis of the joint impact of dose-response models and permeability heterogeneity on aquifer resilience loss due to Bisphenol A contamination
Authors: Im Jinwoo , Rizzo Calogero , de Barros Felipe
Published: March 2022

In this work, we investigate the interplay between dose-response models and permeability heterogeneity on the resilience of an aquifer contaminated with emerging contaminants under uncertainty. We focus our attention to Bisphenol A (BPA) in groundwater which is known to cause endocrine-related effects on humans. Health risks are computed through two distinct BPA dose-response models. The first one is a non-monotonic dose-response (NMDR) model while the second one is a monotonic dose-response (MDR) model. Through the use of a Monte Carlo numerical framework, we simulate transport of BPA from a source to an environmentally sensitive target in a three-dimensional aquifer. Results indicate the importance of considering both hydrological and toxicological information in water resources management. The magnitude and the uncertainty associated with the resilience loss are strongly impacted by the functional shape of the dose-response model and the level of heterogeneity. Further analysis indicates that the role of the ratio of the volumetric flow rate passing through the source zone to the ambient groundwater flow rate in controlling the aquifer resilience loss.
Understanding formation of ice wedges and origin of trapped greenhouse gas at Zyryanka, Northeastern Siberia 
Authors: Ko Nayeon , Park Hansu , Jung Hyejung , Iwahana Go , Fedorov Alexander , Ahn Jinho
Published: March 2022

Multiple geochemical analyses may help us better constrain the ice-wedge formation and in-situ greenhouse gas (GHG) production mechanisms. Here we present new results from ice-wedge ice sampled at Zyryanka, Northeastern Siberia (65°93’N, 150°89’E). The plant remains and CO2 gas were analyzed for 14C dating, and we obtained from 810 to 1750 years before 1950 CE for the Zyryanka ice wedge. δ(N2/Ar) of the ice wedges ranges from -17.51 to -3.53 % with regard to modern air, indicating that the Zyryanka ice wedge was formed by both liquid water and dry snow. On the other hand, the δ(O2/Ar) value of the Zyryanka ice wedges ranges from -72.88 to -37.58 % with regard to modern air, implying oxygen gas was consumed considerably by respiration of microorganisms in the ice-wedge ice. We also observed correlations among the three greenhouse gas species and oxygen gas concentrations. N2O and CO2 concentrations show a strong positive correlation (r = 0.94, p=0.01). We also found that the melting fraction (estimated from N2/Ar) is positively correlated with CO2 (r=0.81, p=0.01) and CH4 (r=0.87, p<0.05). Furthermore, O2 concentration is negatively correlated with the CH4 concentrations (r = -0.41, p<0.05) which may imply that CH4 production is associated with biological oxygen consumption. The δ18O of ice melt ranges from -28.6 to -19.1 ‰ for the ice wedge and adjacent soil samples, showing a symmetric structure with low δ18O values in the ice wedge parts and high in the adjacent soils. Comparing with the δ18O value of modern precipitation in the Zyryanka region, it can be inferred that the ice wedge was mainly formed by filling with cold seasonal precipitation. Our study shows that the gas mixing ratios in ice wedges and water stable isotope analysis may help better understanding the biogeochemical environments during and after the formation of ice wedges.