bluuebunny/crossref_metadata_2025 huggingface dataset:
Designing the next generation of seismic arrays using fibre optic DAS
Authors: Dando Ben , Iranpour Kamran , Wuestefeld Andreas , Näsholm Sven Peter , Baird Alan , Oye Volker
Published: March 2022

While seismic arrays have been in use since the 1950s and are currently a vital part of the IMS, they have fundamentally consisted of single or 3-component seismometers to measure the ground motion at a discrete set of locations known as the array elements. With the advent of Distributed Acoustic Sensing (DAS) within the last two decades, there is currently great interest in exploring the potential seismological applications. In contrast to traditional seismometers, DAS measures the deformation (e.g. strain-rate) along the length of a fibre optic cable with great flexibility in the number of measurements that can be taken and where they are taken along a given cable layout. Applying such technology to seismic arrays offers an exciting opportunity to design array configurations that were previously impractical with individual seismometers. However, the use of DAS requires special consideration of its unique signal characteristics, which include insensitivity of P-waves arriving broadside to the fibre optic cable.

In this paper we present a design study for the installation of a new fibre optical cable at the site of the existing NORES seismic array in Norway – a 1.4 km aperture array located within a subarray of IMS station PS27 (NOA). We demonstrate through the modelling of DAS-specific array response functions how to optimize a new seismic array for regional seismic monitoring, highlighting the importance of incorporating DAS directivity effects. The final design will be installed in 2022 supplementing the current NORES array and will provide a unique data set that could lead to a new generation of DAS seismic arrays for both regional and global seismic monitoring.
Long-term impact of land use change on the simulation of distributed regional-scale groundwater recharge in cold and humid climates
Authors: Dubois Emmanuel , Larocque Marie , Brunner Philip , Gagné Sylvain
Published: March 2022

Although the long-term impacts of climate change on the different water budget components have been widely studied, numerous challenges in accounting for land use (LU) changes in regional scale hydrologic simulations remain. As it can be challenging to map the evolution of LU and incorporate the changes in models, models are often calibrated with the hypothesis that LU is constant through time. Therefore, little is known about the quantitative impact of LU change on the water budget components and more specifically on the regional-scale groundwater recharge (GWR), although it is widely accepted that GWR depends on LU. The objective of this work was to assess the impact of LU changes on the simulation of regional-scale GWR and identify the magnitude of changes to produce significant changes in GWR. GWR was simulated with a transient-state spatialized superficial water budget over three regional-scale watersheds (>2 000 km2) in the cold and humid climate of southern Quebec (Canada). The model computes snow accumulation and snowmelt, as well as soil freezing to provide spatially distributed runoff, actual evapotranspiration, and GWR fluxes with a monthly time step on a 500 m x 500 m grid. Four versions of the model are calibrated over the 1990-2017 period considering constant LU, constant LU and rainfall interception in forested areas, transient LU (annual time step, two data sources), and transient land use and rainfall interception in forested areas. The model versions with transient LU performed better and were calibrated with sets of statistically different parameters while the model versions with rainfall interception did not systematically enhanced the calibration results. Because the observed LU changes were relatively limited during the 1990-2017 period in the study areas, the simulated variables with the four versions were not significantly different. To assess the joint effects of LU change and climate change on GWR, two scenarios of future LU changes were developed and combined with climate change scenarios to simulate future GWR. Results were analyzed to identify the type and intensity of LU changes necessary to produce significant changes in GWR.
An efficient parallel depth-integrated adaptive numerical framework with application to flow-type landslides
Authors: Gatti Federico , Perotto Simona , De Falco Carlo , Formaggia Luca
Published: March 2022

Hydrogeological instability is among the effects of climate change with major impact on people and built environments security. Among instabilities, landslides are responsible for significant human and economic losses worldwide.

Landslide dynamic is characterized by a broad range of velocity-scales, from the steady creeping slip to a catastrophic avalanche passing through the intermittent rapid slip. During these phases, the landslide undergoes different mechanical behaviours. In particular, during the triggering phase, the landslide behaves roughly like a rigid body and the driving process is the pore-pressure diffusion that causes the intermittent slipping of the involved material. Once the landslide is initiated, it follows various behaviours, e.g. we may have a flow-like motion typical of debris and mud flows, where the landslide follows a visco-plastic behaviour and the overall process becomes advection dominated.

We propose an efficient multi-core numerical framework solving a two-dimensional depth-integrated fluid dynamic model for the simulation of flow-type landslides such as debris and mud flows. The governing equations are solved on adaptive quadtree meshes via the classical two-step second order Taylor-Galerkin scheme with a classical flux correction finite element strategy to avoid spurious oscillations near discontinuities and wetting-drying interface. Possible extensions considered by the author, such as an implicit-explicit operator splitting strategy, to deal with stiff diffusion and source terms will be discussed. Extensions that however do not affect the data locality of the scheme so do not affect the efficiency of the parallel implementation. To avoid excessive refinement in non-interfacial regions, we implement an interface tracking strategy that ensures detail preservation at the wetting-drying interface. We test the numerical framework on a real case study located in the Northern Italy to show its ability to deal with real problems.
Ice layer detection, distribution, and thickness in the near-surface firn on Devon Ice Cap: a new dual-frequency radar characterization approach
Authors: Chan Kristian , Grima Cyril , Rutishauser Anja , Young Duncan A. , Culberg Riley , Blankenship Donald D.
Published: March 2022

Atmospheric warming has led to increased surface melting on glaciers in the Arctic. This meltwater can percolate into firn and refreeze to form ice layers. Depending on their thickness, low-permeability ice layers can act as barriers that inhibit subsequent vertical meltwater infiltration in deeper firn pore space and favor lateral meltwater runoff. Thus, characterizing ice layers in firn is key for understanding the near-surface hydrological conditions that could promote surface meltwater runoff and its contribution to sea level rise.

Airborne ice-penetrating radar (IPR) is a powerful tool for imaging subsurface structure, but only recently have these systems been applied to direct observations of the bulk properties of the near-surface. To evaluate the bulk permeability of the near-surface firn system of Devon Ice Cap (DIC), Canadian Arctic, we use the Radar Statistical Reconnaissance (RSR) technique, originally developed for accumulation studies in West Antarctica. This method utilizes both the coherent and incoherent components of the total surface return, which are predominately sensitive to near-surface permittivity/structure within the system’s vertical range resolution and surface roughness, respectively. Here, we apply RSR to IPR data collected over DIC with the High-Capability Airborne Radar Sounder 2 (HiCARS) system (60 MHz center-frequency, 15 MHz bandwidth), operated by the University of Texas Institute for Geophysics (UTIG). Guided by ground-based ice-penetrating radar data and firn core density measurements, we show that the near-surface heterogeneous firn structure, featuring ice layers, mainly affects the observed coherent component.

We further compare the coherent component of HiCARS with that derived from IPR data collected with the University of Kansas Multichannel Coherent Radar Depth Sounder (MCoRDS) 3 system (195 MHz center-frequency; 30 MHz bandwidth), to evaluate the utility of dual-frequency IPR for characterizing near-surface ice layers. We expect that each radar system is sensitive to a different scale of near-surface bulk properties (i.e., depth and thickness of ice layers of different vertical extents), governed by each radar systems’ center frequency and bandwidth-limited range resolution. We leverage these differences in range resolution to derive ice layer thickness constraints in the DIC firn zone containing meter-thick ice layers, which are consistent with ground-based observations. Our results suggest this dual-frequency approach does indeed show that ice layers are vertically resolvable, spatially extensive, and mostly impermeable to surface meltwater. Thus, we hypothesize that lateral flow over high elevation meter-thick ice layers may contribute to the total surface runoff routed through supraglacial rivers down-glacier in the ablation zone.
Investigating the potential of GNSS-modules for inflow avalanche measurements
Authors: Neuhauser Michael , Neurauter Rene , Tuermer Steffen , Gerstmayr Johannes , Adams Marc , Koehler Anselm , Fischer Jan-Thomas
Published: March 2022

A detailed knowledge of avalanche dynamics is crucial to optimize flow models that allow avalanche simulation tools to be effectively used for dimensioning mitigation measures or identifying endangered terrain. There are different ways to observe the dynamics in an avalanche during the flow. It can be achieved with remote sensing approaches or fixed sensor systems that interact with the flow. In this Abstract we introduce an inflow sensor system, the so called AvaNodes that are equipped with a variety of sensors, investigating the potential of Global Navigation Satellite System (GNSS) modules.

The AvaNode is a cube with 16 cm side length. It is designed to flow in the avalanche and obtain GNSS position and velocity, inertial measurement unit (IMU) based accelerations, angular velocities and the magnetic flux densities, and temperature by means of an infrared thermometer.

The utilized GNSS modules are from the ublox CAM-M8 series, that have a position accuracy of 2 m and velocity accuracy of 0.05 m/s, according to the datasheet.

To estimate the position accuracy of the AvaNode while covered with snow, experiments were performed with the AvaNode buried in snow at different depths at a known location. Results show that the position accuracy is highly dependent on the number of satellites that the module currently tracks, ranging between 2 and 10 meters.  To estimate the GNSS velocity accuracy while the AvaNode is covered with snow, a dynamic experiment with moving sensors was performed. The AvaNode was transported on a sledge while it was buried in 10 and 20 cm of snow. An accuracy in the range of 0.5 m/s was observed, allowing to potentially investigate the dynamics in real avalanches. The influence of burial or snow cover depth did not show conclusive influence on the results and requires further investigation. In 2021 this inflow sensor system was used in two avalanche experiments, on March 15 and 16, obtaining start and end positions, as well as promising GNSS velocities. On March 15 one AvaNode was transported by an avalanche, where the GNSS velocity shows a maximum of 15 m/s and a duration of 50 seconds of the avalanche. On March 16 two AvaNodes were picked up by an avalanche, both showing similar velocity distributions, with a maximum velocity of 17 and 13 m/s.
Role of iron-carbon interactions in the release of greenhosue gases from permafrost systems
Authors: Joshi Prachi , Patzner Monique , Chauhan Ankita , Voggenreiter Eva , Wunsch Katrin , Bryce Casey , Kappler Andreas
Published: March 2022

As permafrost thaws, vast stocks of organic carbon previously accumulated within these systems are vulnerable to microbial decomposition and may be released as the greenhouse gases CO2 and CH4. The release of carbon from permafrost systems is expected to lead to runaway positive feedbacks. The timescale and magnitude of the permafrost-climate feedback is highly uncertain as knowledge gaps remain regarding the rate of decomposition of permafrost organic carbon. These knowledge gaps stem, in part, from poor understanding of the association between organic carbon (in the form of organic matter) and minerals, especially high surface area iron minerals. In this work, we investigated the coupling of iron and carbon cycles in permafrost peatlands and its effect on greenhouse gas release. We first showed that up to 20% of the organic carbon in intact permafrost sites may be associated with iron(III) (oxyhydr)oxides and thereby protected from microbial decomposition. At the onset of thaw, this association is broken down, likely due to the microbial reduction of iron(III), and previously protected carbon is thus released. Using microbiological and molecular biological tools, we linked this breakdown to an increase in the abundance of methanogenic microorganisms and concentrations of methane. Preliminary work also suggests that part of the released organic carbon may re-associate with dissolved iron in thaw ponds to form flocs. Currently, we are investigating the molecular composition of organic matter as it undergoes these redox processes with the goal of linking bioavailability to composition. We complement this work with enrichment experiments and microbial community analyses to determine the microbial key players controlling iron(III) reduction and the potential for subsequent microbial Fe(II) oxidation. Collectively, the results of this project suggest that upon thawing, organic matter previously associated with minerals is mobilized and is likely susceptible to microbially-mediated release as CO2 and CH4.
Texturally constrained machine learning thermobarometry and chemometry of the Cumbre Vieja 2021 eruption, La Palma
Authors: Higgins Oliver , Jorgenson Corin , Musu Alessandro , Rodríguez Fátima , Coldwell Beverley , Martín-Lorenzo Alba , Pankhurst Matt , D’Auria Luca , Giordano Guido , Caricchi Luca
Published: March 2022

Magma has a dynamic and often-complex journey from source to surface, the record of which is largely encoded in the chemistry of minerals. Its storage conditions prior to eruption and modifications during ascent can influence eruptive dynamics and eruption duration. We present quantitative 2D chemical maps of clinopyroxene crystals from the Cumbre Vieja eruption (La Palma, Canary Islands; 19th September 2021 – 13th December 2021). The histories of individual crystals are constrained using novel thermobarometric (pressure, temperature) and chemometric (equilibrium melt composition) machine learning algorithms. We identify the remobilisation of colder (~950 ˚C), deeper (2 – 3.5 kbar), and more evolved (1 – 2 wt% MgO) cores by a hotter (1050 – 1100 ˚C) and less-evolved (3.5 – 4.5 wt% MgO) carrier melt. Textural evidence shows resorption of these antecrystic cores suggesting an uninterrupted ascent through the crustal column followed by upper-crustal (~ 1kbar) crystallisation and eruption. By using both quantitative maps and reliable single-phase thermobarometric and chemometric calibrations, we overcome several issues associated with acquiring statistically representative mineral chemistry via single spot analyses. In doing so we precisely track the syn-eruptive evolution of storage pressure-temperature and magma composition. These parameters are then related to the variation of geophysical signals (seismicity, gas monitoring) recorded during the La Palma eruption.
An Examination of Alternate Partitioning Methods for Disdrometer Data
Authors: Brunson Brianna G. , Larsen Michael L.
Published: March 2022

Historically, disdrometer data records have been divided into disjoint, equal-time intervals (often of 1- or 5-minute durations). Previous research of drop-resolving disdrometer data taken by the two-dimensional video disdrometer (Joanneum Research, Graz, Austria) has noted evidence of statistical structures on sub-minute timescales, which could lead to underestimations of rainfall variability when 1- or 5-minute partitionings are used. Here, we introduce and explore alternatives to the standard fixed-duration partitioning of disdrometer data. We compare the distributions of standard bulk rain measurements (rainfall rate and mass weighted mean diameter) under each partitioning method to demonstrate the utility of these alternative partitioning methods.
Integrating astronomical solutions and geological observations
Authors: Sinnesael Matthias , Laskar Jacques
Published: March 2022

Some of the large climatic changes of the past originate in the variations of the Earth’s orbit and of its spin axis resulting from the gravitational pull of the planets and the Moon. These variations can be traced over several millions of years back in time (Ma) in the geological sedimentary records (e.g. Milankovitch cycles). Over the last decades, the Earth’s orbital and spin solutions have been used to establish a geological timescale based on the astronomical solutions. Nevertheless, extending this procedure through the Mesozoic Era (66-252 Ma) and beyond is difficult, as the solar system motion is chaotic. It will thus not be possible to retrieve the precise orbital motion of the planets beyond 60 Ma from their present state.

Astrogeo, a project funded by the European Research Council (ERC), will use the geological record as an input to break the horizon of predictability of 60 Ma resulting from the chaotic motion of the planets. This will be achieved by considering statistical methods and by using ancient geological data as an additional constraint in obtaining astronomical solutions. Astrogeo aims to provide a template orbital solution for the Earth that could be used for paleoclimate studies over any geological time. This will open a new era where the geological records will be used to retrieve the orbital evolution of the solar system. It will thus open a new observational window for retrieving not only the history of the Earth, but of the entire solar system. Here, we want to reach out to the broader cyclostratigraphic community to discuss suitable procedures and data sets to couple both theoretical solutions and geological observations. In particular, we are interested in examining high-quality data sets with clear and well-constrained (single or combined) expressions of the astronomical parameters of eccentricity, precession and obliquity.
Biogenic aerosol composition on the North Slope of Alaska
Authors: Moffett Claire , Mehra Manisha , Barrett Tate , Gunsch Matthew , Pratt Kerri , Sheesley Rebecca
Published: March 2022

As the Arctic continues to change and warm rapidly, it is increasingly important to understand the contribution of biogenic sources to Arctic aerosol. Biogenic sources of primary and secondary aerosol in the arctic will be impacted by climate change, including warming and earlier snow and ice melt, while local emissions and long-range transport can drive changes in anthropogenic aerosol. This study focuses on identifying the contribution of biogenic aerosol to organic carbon (OC) and its seasonal trends through the analysis of aerosol chemical and isotopic composition. Aerosol samples were collected at two sites on the North Slope of Alaska (Utqiaġvik and Oliktok Point) over the summer of 2015 and from June 2016 through August 2017. Organic carbon concentrations correlated well between the sites with high contribution from contemporary sources. Backwards air mass trajectory analysis indicates that source regions are primarily marine in the summertime. Methanesulfonic acid (MSA) was utilized to confirm this marine influence. Secondary organic aerosol confirmed the contribution of terrestrial biogenic sources to organic aerosol at both sites. Strong correlations between ambient temperature and MSA and OC were found during the summer. This study provides a multiyear characterization of organic carbon highlighting the high biogenic influence and indicating areas of interest for future research.
Future global glacier mass changes and their impact on sea level and streamflow
Authors: Hock Regine
Published: March 2022

Concurrent with atmospheric warming, glaciers around the world are rapidly retreating with direct consequences for global sea level and streamflow. Projections indicate considerable mass losses over the 21st century, however, mass losses vary strongly between regions and emission scenarios. In some regions with little ice cover projections forced by high emission scenarios show almost complete deglaciation by the end of the 21st century while in high-polar regions the relative mass losses are generally in the order of a few tenths of percent relative to year 2015. The mass losses alter local runoff regimes and lead to glacier runoff increases in some regions but to decreases in others. Global glacier changes are linearly correlated with global mean temperature increase indicating that limiting global warming has a direct effect on future glacier mass changes.
West-Siberian meridional carbon transect: the concept
Authors: Smirnov Pavel , Tolstikov Andrey
Published: March 2022

Last year, in Russia there was started a new government long-term initiative, that aims reduction for Russian greenhouse gas emissions by up to 70 percent compared to the 1990 level in less than next 10 years (by 2030).

On the one hand such ambitious goal to includes massive technical and industrial modernization and other hand – supposed to provide valid, verified and globally recognized scientific data on the runoff and emission of greenhouse gases from ecosystems all around Russia. Thus, a large-scale program for the development of carbon stations has started with running of carbon polygons, which should combine both research-methodological and educational functions, and, eventually, contribute to the achievement of the specified state objective. The educational function of the polygons includes training personnel with interdisciplinary competencies to work on "carbon" topics, including the highest qualifications.

Starting to design and equip the first running polygon in the Tyumen region (by University of Tyumen), we initially stated concept of creating an ecological and climatic transect across the whole of Russia from north to south. The general idea is connect the new carbon polygon near Tyumen with carbon monitor infrastructure in proposed polygons and stations in Tobolsk and Ishim, Khanty-Mansiysk (Mukhrino) and Yamalo-Nenets (Labytnangi)Autonomous Disctricts. With potential sites in partners, that University of Tyumen has in Central Asian republics, there are prospect to continue this meridional transect further to the south. And in this case, we have the prospect of getting a global-scale monitoring system in the center of Eurasia across all natural zones from north to south, that provide massive raw data set for global observation system.
Investigating the levels of Geomagnetically Induced Currents in the Mediterranean region during the most intense geomagnetic storms of solar cycle 24
Authors: Boutsi Adamantia Zoe , Balasis Georgios , Daglis Ioannis A. , Tsinganos Kanaris , Giannakis Omiros
Published: March 2022

Geomagnetically Induced Currents (GIC) constitute an integral part of space weather research and are a subject of ever-growing attention for countries located in the low and middle latitudes. A series of recent studies highlights the importance of considering GIC risks for the Mediterranean region. Here, we exploit data from the HellENIc GeoMagnetic Array (ENIGMA), which is deployed in Greece, complemented by magnetic observatories in the Mediterranean region (Italy, France, Spain, Algeria and Turkey), to calculate values of the GIC index, i.e., a proxy of the geoelectric field calculated entirely from geomagnetic field variations. We perform our analysis for the most intense magnetic storms (Dst < -150 nT) of solar cycle 24. Our results show that GIC indices do not exceed low activity levels despite the increase in their values, at all magnetic observatories / stations under study during the selected storm events.
A comparison between the magnetohydrodynamical modes of plesio-geostrophy and fully 3D calculations
Authors: Holdenried-Chernoff Daria , Jackson Andy , Maffei Stefano
Published: March 2022

An ever-expanding catalogue of satellite data has laid the foundations for new studies of Earth’s secular variation and acceleration. Studies that encode a-priori the axial rigidity conferred to core flows by the Earth’s rapid rotation have revealed novel fast dynamics and improved estimates for the magnetic field strength inside the core. Within this context, a new formalism christened “plesio-geostrophy” (PG) was developed by Jackson and Maffei (Proc. Roy. Soc. A, 476(2243), 2020) with the purpose of describing core dynamics in a regime closer to Earth's conditions. This model makes use of axial integration of the equations of fluid motion and magnetic induction to collapse all three-dimensional quantities into two-dimensional scalars. We report on new results within the PG formalism.

We consider the dynamics of a conducting, inviscid fluid in a full sphere subject to various background magnetic fields. The eigenmodes sustained by the Coriolis and Lorentz forces split into two branches: a fast and a slow one. We characterise these eigenmodes and compare their structure and frequency to fully three-dimensional results. Previous studies are extended by incorporating the effects of horizontal magnetic diffusion.
JIRAM observations of Jupiter's upper troposphere
Authors: Grassi Davide , Mura Alessandro , Sindoni Giuseppe , Adriani Alberto , Atreya Sushil , Filacchione Gianrico , Fletcher Leigh , Lunine Jonathan , Moriconi Maria Luisa , Orton Glenn , Plainaki Christina , Tosi Federico , Olivieri Angelo , Eichstaedt Gerald , Hansen Candice , Dinelli Bianca Maria , Migliorini Alessandra , Piccioni Giuseppe , Bolton Scott
Published: March 2022

The Jovian Infrared Auroral Mapper (JIRAM, a payload element of the NASA Juno mission to Jupiter) includes an infrared spectrometer covering the 2.0–5.0 μm range. After reviewing the main results on the conditions of upper troposhere derived from the solar-dominated 2.0–3.2 μm spectral range and presented in Grassi et al. 2021, we focus our discussion on open modeling issues and recent attempts to study these altitudes from data in the thermal-dominated 4.0-5.0 μm spectral range. We present also the results of an automatic classification of data performed on the basis of the HDBSCAN algorithm (McInnes et al. 2017). We show that similar spatial patterns are obtained either considering the coefficents of a PCA performed directly on spectra or on the physical parameters (clouds altitude, haze thickness) retrieved by the algorithm adopted in Grassi et al. 2021.

 

Grassi et al. 2021   doi:10.1093/mnras/stab740

McInnes et al. 2017   doi:10.21105/joss.00205

 
Solute migration through unsaturated fractured chalk under variations in saturation degree, flow rate and aperture
Authors: Weisbrod Noam , Roded Sari , Klein-BenDavid Ofra , Turkeltaub Tuvia
Published: March 2022

Spent fuel (SF) produced in the nuclear industry, requires long term disposal solutions for 105-106 years, to allow its decay in an isolated setting as means to reduce the environmental threat of radioactive contamination. The feasibility of locating SF repository within a fractured carbonate formation as the host rock in the unsaturated zone, requires better understating of radionuclide transport patterns under these specific conditions. An innovative system was developed to simulate conditions of unsaturated flow and transport in fractured chalk. The system consists of an artificially fractured chalk core, situated in a flow cell, which lays on top of a ceramic membrane. The membrane separates it from a lower sealed cell where constant negative pressure is forced. Subsequently, a pressure gradient along the rock core is being developed. The system is placed on a scale in order to monitor the degree of saturation in the core throughout the experiment. Uranine fluorescent dye is used as a conservative tracer to investigate the impact of: (1) the initial degree of saturation; (2) fracture aperture; and (3) flow rate, on the transport and recovery of conservative contaminants. Preliminary results show that a conservative tracer migrates faster through the fracture when the matrix is initially nearly saturated (s=99%) than when the matrix is undersaturated (s=75%). These results will be used for comparison with radionuclide and radionuclide-simulants transport in current studies.
Restored fen vegetation following in situ well pad disturbances
Authors: Lemmer Meike , Xu Bin , Strack Maria , Rochefort Line
Published: March 2022

In the Oil Sands region of Alberta, Canada, vast areas of the boreal forest, including pristine northern peatlands, are under pressure by an extensive infrastructure of the oil and gas industry for bitumen production. Disturbances include a wide net of access roads, pipelines, processing facilities and thousands of in situ oil and gas well pads. Well pads are platforms of 1 to 4 m compacted mineral fill, sized 1 to 4 ha, supporting in situ oil and gas scheme wells for bitumen production. As of November 2021, there were more than 42 500 active wells in Alberta, each with a lifespan of about 20 years. Once well pads are no longer in use, peatland restoration is obligatory. The restoration aim is the reestablishment of important peatland functions, such as wildlife habitat, water storage and filtration, peat accumulation, and carbon sequestration.

Our research focuses on the development of characteristic fen vegetation in restored peatlands following disturbances by in situ oil sands well pads in the Peace River and Cold Lake Oil Sands regions in Alberta. We aimed to evaluate different restoration techniques, including 1) the complete removal (CR) of a well pad’s mineral fill and spontaneous revegetation via natural ingress 2) the partial removal (PR) of the mineral fill to the water table level (PR0) and spontaneous revegetation, and 3) the PR of the mineral fill to 15 cm above the water table level (PR15) and 4 to 6 cm above the water table level (5 cm), and planting of specific fen species seedlings (Carex aquatilis, Larix laricina, and Salix lutea). We assessed the return of plant species and community diversity, biochemical quality of the substrate and ecohydrology of the restored peatlands (CR, PR0, PR15, PR5), an unrestored control area, and 28 reference wetland areas (REF), including a marsh, fens, and bogs.

Ten years post-restoration, the CR had developed into a shallow open water area with a larger than 80 cm water table and floating moss carpets along the edges. In PR, the levelling of the mineral fill reconnected the surface to the adjacent undisturbed fens and resulted in a surface-near water table and highest peatland plant species diversity. We observed a total plant cover of 57% in the restored areas, compared to 68% in REF. In the restored areas 61% of the vegetation, with an average of 35 species, comprise characteristic peatland species, compared to 100% in the REF, where an average of 64 species were observed. Across all restored areas, a close hydrologic connection to the adjacent peatland with a water table close to the surface resulted in plant communities similar to reference fens and with the highest peatland plant species diversity among restored areas.
Global attribution of microclimate dynamics to industrial deforestation sites using thermal remote sensing and machine learning 
Authors: Tkachenko Nataliya , Garcia Velez Laura
Published: March 2022

Microclimate is a relatively recent concept in atmospheric sciences, which started drawing attention of engineers and climatologists after proliferation of the open thermal (infrared, middle- and near-infrared) remote sensing instruments and high-resolution emissivity datasets. Rarely mentioned in the context of global climate change reversing, efficient management of microclimates nevertheless can be considered as a possible solution. Their function is bi-directional; On one hand, they can perform as ‘buffers’ by smoothing out effects of the already altered global climate on people and ecosystems, whilst also acting as the structural contributors to perturbations in the higher layers of the atmosphere. 

In the most abstract terms, microclimates tend to manifest themselves via land surface temperature conditions, which in turn are highly sensitive to the underlying land cover and use decisions. Forests are considered as the most efficient terrestrial carbon sinks and climate regulators, and various forms, configurations and continuity of logging can substantially alter the patterns of local temperature fluxes, precipitation and ecosystems. In this study we propose a novel heteroskedastic machine learning method, which can attribute localised forest loss patches due to industrial mining activity and estimate the resulting change in dynamics of the surrounding microclimate(s). 
Daytime-only-mean data can enhance our understanding of land-atmosphere coupling
Authors: Yin Zun , Findell Kirsten , Dirmeyer Paul , Shevliakova Elena , Malyshev Sergey , Ghannam Khaled , Raoult Nina , Tan Zhihong
Published: March 2022

The major concern of land-atmosphere interactions (L-A) is the evolutionary process between the land surface and the planet boundary layer during the daytime, however many relevant studies had to use entire-day-mean daily time series to perform investigation due to lack of sub-daily data. Yet it is unclear whether the inclusion of nighttime data would alter the results or obscure the L-A interactive processes. To address this question, we generated daytime-only-mean (D) and entire-day-mean (E) daily data based on the ERA5 (5th ECMWF reanalysis) hourly product, and evaluated the strength of L-A coupling through a two-legged metrics, which assessed the coupling strength by the causality as well as the impact magnitude through two segments (land-fluxes and fluxes-atmosphere). The results demonstrated significant differences between the D- and E-based diagnoses as large as 67% (median 20.7%), which strongly depended on the season and the region. More importantly, for the first time, two special L-A coupling mechanisms were revealed. One was the advection-dominant L-A mechanism in tropical hyper-arid regions. The other was the soil moisture and sensible heat flux coupling mechanism during the cooling process over the nighttime. Both processes may play important roles during the night, andweaken the signal of L-A coupling if E was applied. To improve our knowledge of L-A interactions, we call attention to the urgent need for more high frequency data for relevant diagnoses. Meanwhile, we propose two approaches to resolve the dilemma of huge storage for high frequency data: (1) integration of L-A metrics in Earth System Model outputs, and (2) production of daily datasets based on different averaging algorithms.
Formation and contractional reactivation of the NW Sulu Sea (SE Asia)
Authors: Cadenas Patricia , R. Ranero César
Published: March 2022

Located in SE Asia in between the Palawan and the Philippine islands, the lozenge-shaped Sulu Sea corresponds to a marginal sea that displays a complex seafloor morphology. The NE-SW trending Cagayan Ridge separates a southeastern deep-water domain, which is bounded by the Sulu Trench towards the east, from a shallower and narrower northwestern domain. Interpretations of low-resolution 2D streamer datasets, ODP Leg 124 drilling results, magnetic, geochemical, and geochronological studies, and gravity inversion results led to distinctive tectonic models, with contrasting basin formation mechanisms, and ages of opening and subsequent contractional reactivation. The debates remain because the structure of most of the Sulu Sea and its along-strike structural variability remain underexplored to date.

We focus on this work on the first detailed analysis of the structure and seismo-stratigraphy of the NW Sulu Sea. Based on the reprocessing, calibration of the Silangan-1 exploration borehole, and interpretation of > 5384 km of 2D seismic data along 19 regional profiles of an irregular grid that covers the whole NW Sulu Sea, we identify, map and interpret the seismo-stratigraphic horizons and units, major structures, and rift-related and syn-orogenic depocenters and structural domains. We define six seismo-stratigraphic units in the NW Sulu Sea, consisting of Quaternary to Paleogene sediments, which developed during an early phase of Paleogene to early Miocene extension, a following early to Middle Miocene phase of contraction, and a late Miocene to Quaternary stage of relative tectonic quiescence. While transpressional faults core uplifted basement areas, strike-slip, high-angle and low-angle oblique extensional faults crosscut continental crystalline basement of variable thickness and bound pull-apart basins, half-grabens and sags respectively. The distribution and trend of rift-related depocenters describe a strong structural segmentation and vary along NW-SE and NE-SW oriented zones. Thrust-cored anticlines, inverted transtensional and transpressional faults and mud diapirs deform the sediment pile and control the geometry of syn-orogenic depocenters distinctively across the NW Sulu Sea.

Normal and oblique trending sets of faults controlled the extension and compartmentalized the NW Sulu Sea. Subsequent contractional reactivation differentiated NE and SW basement and sedimentary domains, separated by the NW Sulu Break Elevation. These domains show a contrasting overall architecture, basement thickness, contractional structures and distribution of rift-related and syn-orogenic depocenters. Rift segmentation, and particularly, basement thickness variations, may have conditioned the type and distribution of contractional deformation.
Modeling the effects of low flow on wood transport in the Piave River
Authors: Persi Elisabetta , Petaccia Gabriella , Sibilla Stefano , Picco Lorenzo , Tonon Alessia
Published: March 2022

In low flow conditions, wood transport is limited but still important. In addition, low flows are significant to stress a numerical model of Large Wood (LW) transport and to assess its capacity in simulating LW displacement or non-displacement.  The solver ORSA2D_WT was employed and tested to improve the knowledge related to these thresholds (moving vs not moving). The software couples the solution of the 2D Shallow Water Equations to a dynamic Discrete Element Model that computes the hydrodynamic forces to calculate LW transport. To assess whether ORSA2D_WT can cope with the infrequent mobilization of LW in low flow conditions, it is applied to a reach of the Piave River (North-East Italy), where the wood budget was already investigated. Field data about LW position, mobilization, shape, size and orientation, flow conditions and morphological changes were collected.

The critical aspects that affect the model performance and that deserve an in-depth analysis are the wood-riverbed interaction and the log shape representation in the model. ORSA2D_WT works in fixed-bed conditions, computing a 2D force balance to determine wood entrainment. It considers only cylindrical forms or jams composed by cylindrical elements, whose relevant hydrodynamic parameters are the longitudinal cross-section and the hydrodynamic coefficients, that depend also on the log orientation to the flow.

Regarding wood-riverbed interaction, bed friction plays a significant role compared to the forces that trigger wood motion. This is especially true in low flow conditions when floatation is less important than rolling/sliding. The local erosion that occurs nearby wood pieces likely influences wood mobilization, as well as the presence of roots and/or branches.

To assess if the model schematizations are sufficiently accurate for low flow conditions and to overcome the model limitations, the friction and hydrodynamic coefficients are suitably corrected. In particular, the influence of the local water level on the friction coefficient is investigated, and the hydrodynamic coefficients are modified to include different LW shapes. The modified model is calibrated with the data available for one sub-reach and then applied to a different sub-reach, to assess its performance.
Nitrosat: Nitrosat: Mapping reactive nitrogen at the landscape scale 
Authors: Levelt Pieternel , Coheur Pierre ,   Nitrosat Science Team
Published: March 2022

 
 

The nitrogen cycle has been heavily perturbed due to ever growing agriculture, industry, transport and domestic production. It is believed that we now have reached a point where the nitrogen biochemical flow has exceeded its planetary boundary for a safe operating zone. This goes together with a cascade of impacts on human health and ecosystems. To better understand and address these impacts, there is a critical need to quantify the global nitrogen cycle and monitor its perturbations on all scales, down to the urban or agricultural source. The Nitrosat concept, which was preselected recently in the framework of ESA’s Earth Explorer 11 call and is entering Phase0 activities, has for overarching objective to simultaneously identify the emission contributions of NH3 and NO2 from farming activities, industrial complexes, transport, fires and urban areas. The specific Nitrosat science goals are to: Quantify the emissions of NH3 and NO2 on the landscape scales, to expose individual sources and characterize the temporal patterns of their emissions. Quantify the relative contribution of agriculture, in its diversity of sectors and practices, to the total emissions of reactive nitrogen. Quantify the contribution of reactive nitrogen to air pollution and its impact on human health. Constrain the atmospheric dispersion and surface deposition of reactive nitrogen and its impacts on ecosystems and climate; and contribute to monitoring policy progress to reduce nitrogen deposition in Natura 2000 areas in Europe. Reduce uncertainties in the contribution of reactive nitrogen to climate forcing, atmospheric chemistry and interactions between biogeochemical cycles. To achieve these objectives, Nitrosat would consist of an infrared Imaging Fourier Transform Spectrometer and a Visible Imaging Pushbroom Spectrometer. These imaging spectrometers will measure NH3 and NO2 (respectively) at 500 m, which is the required spatial scale to differentiate, identify and quantify the main point and area sources in a single satellite overpass. Source regions would be probed from once a week to once a month to reveal the seasonal patterns. Combined with air quality models, assimilation and inverse modelling, these measurements would allow assessing the processes that are relevant for the human disruption of the nitrogen cycle and their resulting effects, in much more detail than what will be achieved with the satellite missions that are planned in the next decade. In this way, Nitrosat would enable informed evaluations of future policies on nitrogen emission control. This presentation will detail the mission concept, provide first results from the Phase 0 scientific studies and from supporting aircraft campaigns.

 
Using Stable Isotopes to Assess Surface-Groundwater Interactions and Contaminant Pathways in a Drinking Water Supply Watershed System
Authors: Carneiro Marques Amanda , Kumpel Emily , Tobiason John , Guzman Christian
Published: March 2022

The assessment of surface-groundwater fluxes is crucial for understanding pollutant pathways through the natural environment. Several techniques to characterize these surface-subsurface interactions have been applied as an attempt to quantify these fluxes in the humid temperate Northeastern USA. Most recently, stable isotopes are considered to be an important tool to describe the movement of waters through the hydrosphere. This study was conducted in the Quabbin-Wachusett Reservoir System, which supplies water for the Boston Metropolitan Area in Massachusetts and depends on water quality management based on environmental trends. Recent trends indicate that despite efforts to reduce road salt application during the winter, salt indicator trends are still increasing in the watershed. Salt transport characterized by monitoring trends of specific conductivity and chloride across the watershed demonstrate that subsurface water concentrations are significantly higher than the streams and reservoir (for chloride, median value is 204 mg/L for wells and 102 mg/L for streams). The present investigation hypothesizes that salt infiltrates through the subsurface during the cold months (October-March) and then releases back to surface water throughout the year. Since groundwater can act as salt storage, an important question for water management relates to the timeframe needed to observe a reduction of salt presence in the watershed after road salt reduction policies and other mitigation strategies take place. To investigate this, oxygen isotopes are being used to identify the dominant hydrological pathways influencing groundwater recharge patterns.  Stable water isotope compositions for warm precipitation (δ18O -2.14 to -8.98 per mille), cold precipitation (δ18O -4.57 to -13.57 per mille), and groundwater (δ18O -8.27 to -9.66 per mille) were used to assess proportional recharge dominance via local winter and summer precipitation isotope end-members. Preliminary analyses indicate that the groundwater recharge is winter dominant (92% obtained from the winter bias seasonal recharge ratio Rwinter/Rannual; values >= 80% represent winter dominance), thus the applied road salt during cold months can be contributing to sustained increases in conductivity in the groundwater. The results show potential dynamics that explain higher levels of specific conductivity and chloride in the subsurface water and the continued increases in stream and reservoir concentrations. Further investigation is being conducted with larger datasets in order to have a better understanding of sample frequency needed to be representative of the system’s predominant seasonal recharge and runoff generation patterns, as well as, how the water isotopic composition is variable spatially and temporally in the region.
Parameter inference and uncertainty quantification for an intermediate complexity climate model
Authors: Roeder Benedict , Schloer Jakob , Goswami Bedartha
Published: March 2022

Well-adapted parameters in climate models are essential to make accurate predictions
for future projections. In climate science, the record of precise and comprehensive obser-
vational data is rather short and parameters of climate models are often hand-tuned or
learned from artificially generated data. Due to limited and noisy data, one wants to use
Bayesian models to have access to uncertainties of the inferred parameters. Most popu-
lar algorithms for learning parameters from observational data like the Kalman inversion
approach only provide point estimates of parameters.
In this work, we compare two Bayesian parameter inference approaches applied to the
intermediate complexity model for the El Niño-Southern Oscillation by Zebiak & Cane. i)
The "Calibrate, Emulate, Sample" (CES) approach, an extension of the ensemble Kalman
inversion which allows posterior inference by emulating the model via Gaussian Processes
and thereby enables efficient sampling. ii) The simulation-based inference (SBI) approach
where the approximate posterior distribution is learned from simulated model data and
observational data using neural networks.
We evaluate the performance of both approaches by comparing their run times and the
number of required model evaluations, assess the scalability with respect to the number
of inference parameters, and examine their posterior distributions.