bluuebunny/crossref_metadata_2025 huggingface dataset:
A Network Analysis Approach to Infrastructure Resiliency to Compounding and Nonstationary Threats
Authors: Zimmerman Julia , Chung Sukhwan , Everett Cassandra , Maze Grace , Savant Gaurav , Kurth Margaret
Published: February 2023

Urban infrastructure systems are vulnerable to both anthropogenic and natural threats that have inherent uncertainty in scale, impact, directness, and timing. Traditional risk management approaches neglect to prepare for both compound disturbance that are not well defined or are novel and for non-stationary threats including future coastal scenarios impacted by sea level rise. Thus, a framework for evaluating the resilience of an infrastructure system rather than its’ risk tolerance is required.In this work, resilience is defined as the ability of a system to prepare for, withstand, recover from, and adapt to future unknown disruptions. New York City NY, Gulfport MS, and Camp Lejeune NC were chosen as case study locations to evaluate a framework combining threat data and network analysis. For the current case studies threat data principally consists of flood depths from hydrologic models and the transportation network was used for analysis. Compound disturbances, consisting of GSSHA flood model output during Super Storm Sandy and randomized bridge failures were applied to the New York City roadway network. The impacts of this were analyzed using 10-minute travel time ego-nets around critical points in the city including hospitals, fire stations, and FEMA shelters. Compound disturbances near Camp Lejeune were represented on a regional level including NC-DOT regions one, two, and three with flooding data provided by FIMAN-T. For this location both the transportation network and the power grid were considered. In Gulfport, sea level rise was projected out to 2100 and used to drive an Adaptive Hydraulics 2D Shallow Water (AdH-SW2D) model of the area. This nonstationarity was added to with the inclusion of different river flow scenarios retrieved from StreamStats, a USGS tool. A similar effort was undertaken for Camp Lejeune, North Carolina.This work aims to take knowledge and developed processes from the case studies described above to create a framework for resilience quantification. This framework will be able to take in threat data from a variety of sources and disciplines and apply this data any infrastructure network. The framework would enable forecasted or near-real time emergency response to natural hazards. Additionally planned infrastructure improvements and new construction could be efficiently evaluated for resilience during the design phase.
Transdisciplinary connections help understand natural mechanisms behind major seismic ruptures
Authors: Ferrand Thomas P. , Eberhard Lisa , Gilio Mattia , Parameswaran Revathy
Published: February 2023

For decades, millions of people have been waiting for the "big one" in either Tokyo, Istanbul or Los Angeles. No one is able to predict where and when such a disaster will happen first. People expect it as a self-evident fact, will experience it as a stroke of fate, and will speak of it as a “tragedy”.Our aim cannot be (yet?) to predict where and when major earthquakes will occur, because that would amount to claiming to be able to announce in advance where and when the lightning strikes. Nevertheless, we believe that our understanding of the seismic process and associated risk should greatly benefit from the following question: what parameters control whether a dynamic rupture nucleates, grows or stops?It is crucial to understand the processes and conditions causing the initial stages of catastrophic rock tearing under pressure, and the interplay between mineral- and tectonic-scale factors. Both fluid percolation events and transformation-driven stress transfers can trigger mechanical instabilities ultimately causing rupture nucleation. And once a rupture has nucleated, similar processes should also occur within the damage zone and modulate the ability of small ruptures to “self-propagate” towards large seismic events.Our lack of understanding is considerable about the exact conditions for rupture nucleation and dynamic propagation. While observational methods help image mechanical instabilities, laboratory experiments provide insights on the physics of the lubrication processes enabling seismic faults to grow under pressure. Unfortunately, there remains a significant gap in scientific communication between researchers using different analytical methods or conceptual views.Here we outline transdisciplinary connections between the contributions to the session. From seismology to electrical conductivity measurements in the laboratory, from field geology to numerical modelling, from machine learning to mineralogy, from geodesy to mineral physics, here we walk on the frontier of knowledge in order to reshape the central questions that we need to ask to further investigate the rupture phenomenon.
The role of turbulence and double-diffusion in the exchange of central waters at the Cape Verde Frontal Zone
Authors: Valencia Luis P. , Rodríguez-Santana Ángel , Martínez-Marrero Antonio , Burgoa Nadia , Gordo Carmen , Grisolía Diana , Marrero-Díaz Ángeles
Published: February 2023

The Cape Verde Frontal Zone (CVFZ) separates North and South Atlantic Central Waters (NCAW and SACW, respectively) in the eastern North Atlantic Subtropical Gyre. This front is described as a strong meandering thermohaline front near Cape Blanc at latitudes close to 20ºN. It shows sharp gradients in temperature and salinity in the upper 600 m with the presence of large lateral intrusions. One important aspect of the CVFZ is the compensating character of the temperature and salinity fields, which cause horizontal density gradients to be relatively small across the front. This frontal feature is an important factor in reducing vertical shear of horizontal velocity in some parts of the frontal region, allowing double diffusion processes to be one of the main causes of the observed diapycnal mixing. However, the presence of large lateral intrusions could favor diapycnal mixing induced by vertical shear instabilities which could overcome double diffusion effects. Despite its importance, studies in the CVFZ with direct turbulence measurements focused on diapycnal mixing and its relation with lateral thermohaline intrusions are scarce. In this study, we use microstructure measurements from a vertical free-falling profiler together with CTD-O and SADCP records of two high spatial resolution (each oceanographic stations ~9 km apart) oceanographic transects along and across the CVFZ (~300 and 100 km, respectively) during November of 2017. An assessment of the turbulent and double-diffusive mixing related to the lateral intrusions was made, identifying the latter through the diapycnal spiciness curvature method. Lateral intrusions ranging from ~20-100 km at subsurface and central levels of the water column showed relative increments in dissipation and diapycnal diffusivity. Therefore, at their boundaries occur the exchange of properties between the NACW and SACW.
Exploring oceanic heat pathways along the George V Land continental shelf
Authors: Dawson Eliza , Wilson Earle
Published: February 2023

Ocean circulation patterns along the continental shelf in the Australian Antarctic Basin remain poorly understood due to the scarcity of in-situ observations and limited modeling studies. In this dynamically complex and climatically important region, the Ross Gyre, Antarctic Slope Current, and Antarctic Circumpolar Current converge just offshore of the George V Land continental shelf. If warm deep water could access the continental shelf and increase basal melt rates along the George V Land coastline, marine-terminating glaciers in the region could retreat and threaten the stability of the vast Wilkes Subglacial Basin. Here, we explore potential pathways for warm deep water to access the shelf along the George V Land coastline using output from the Southern Ocean State Estimate (SOSE) model. We use the SOSE output to map bottom temperatures and identify where warm bottom water could come close to the grounding line due to bathymetric steering. While SOSE provides observationally constrained hydrographic estimates along the George V Land continental shelf, there are substantial discrepancies between the model’s estimates and observations. Most notably, SOSE does not reproduce the dense, high salinity shelf waters observed in the region. SOSE is a model-generated best fit to Southern Ocean observations, so biases could be present in sparsely sampled regions like this one. To further examine the dynamics of this region, we also present preliminary results from an idealized ocean circulation model that explores the sensitivity of cross-shelf heat transport to changes in local heat and wind forcing.
GOES EUVS Magnesium II Index: The beginning of a new climate data record
Authors: Snow Martin , McClintock William , Machol Janet , Eparvier Frank , Woodraska Don
Published: February 2023

The GOES-R series spacecraft include a new operational measurement for GOES satellites, the Magnesium II (MgII) core-to-wing index.  This solar activity proxy has been measured at a daily cadence beginning in 1978.  It is widely used in solar spectral irradiance models such as the NRLSSI CDR (Coddington et al. 2016).  The C Chanel of the Extreme and Ultraviolet Spectrograph (EUVSC) on GOES 16 began making operational MgII index measurements at high cadence in early 2017.  There are currently three such instruments in orbit on GOES 16, 17, and 18 as part of the EXIS suite of solar irradiance instruments.  In the past, the MgII index was only measured a few times per day, but EXIS makes measurements at a 3-second cadence to monitor rapid changes in the Sun.In this presentation, we will describe the available data product and how it compares with previous measurements.  On long timescales it can be used to extend the historical record, and on short timescales it reveals solar activity of interest to space weather practitioners.
Interaction of Internal Gravity Waves with Meso-Scale Eddies
Authors: Sebastia Saez Pablo , Eden Carsten , Chouksey Manita
Published: February 2023

We investigate the interaction of internal gravity waves (IGW) with mesoscale eddies using the novel numerical Internal Wave Energy Model (IWEM). With IWEM, we integrate the radiative transfer equation to investigate the propagation and refraction of IGWs, and the energy exchange between IGWs and mean (eddying) flow. We evaluate the evolution of a typical IGW spectrum with energy density in physical and wavenumber space along a single column and over an eddy cross-section. We compare the simulations with the observations of a coherent mesoscale eddy in the Canary Current System. Results show that the changes in IGW energy are dominated by wave propagation effects, wave-mean flow interaction and wave breaking at critical layers, while wave capture effects are two orders of magnitude smaller. The wave propagation terms transport IGW energy from the eddy center to the rim. Energy gain by wave-mean flow interaction is dominated by low-frequency waves in the eddy center, while high-frequency waves are trapped in a cyclo-stationary up-/downward propagation cancelling out their gain or loss of energy. Energy loss by wave-mean flow interaction or wave breaking is largest at the eddy rim, where IGWs undergo a downscale energy transfer to small vertical scales and to the inertial frequency. Mooring observations agree with our model results on higher IGW energy values at the eddy center compared to the rim.  Following the Osborn-Cox relation, wave-breaking induced vertical diffusivities are found to be maximal at the eddy rim and range between κ≅10-7-10-5m2s-1, partly in range with the observed values in the ocean. The interaction of IGWs and mesoscale eddies is therefore a plausible process for explaining the near-surface enhanced mixing. 
A comprehensive study of gradient and smoothness regularization operators on unstructured tetrahedral meshes
Authors: Farquharson Colin , Kangazian Mitra
Published: February 2023

The regularization function in minimum-structure, or “Occam’s”, style of inversion can stabilize the underdetermined inverse problem and generate models with certain characteristics. The regularization term measures the amount of structure added to the model using the spatial gradient operators. The method commonly employed for calculating the gradient operators on unstructured tetrahedral meshes calculates the physical property differences across the cell faces of two adjacent cells. However, this method is not able to incorporate orientation information of the geological structures such as strike, dip, and tilt angles into the inversion. Providing this information for the inversion leads to constructing geophysical models that have a sensible representation of the true Earth models, especially when geophysical data with limited depth resolution such as gravity and magnetics data are inverted. Designing spatial gradient operators that allow one to incorporate this geological orientation information into the inversion on unstructured tetrahedral meshes is not as straightforward as for structured meshes due to the geometrical complexity of the unstructured tetrahedral meshes.
A few methods have been proposed for calculating the gradient operators for unstructured tetrahedral meshes that allow one to incorporate orientation information into the inversion framework and obtain more sensible geophysical models. Most of these methods consider a cell along with its nearest neighbours as a package and commonly use an l2 norm for the measure of the regularization term. These methods work well, however, the constructed models using these regularization methods are not as sharp as expected if an l1-type measure of roughness is used instead of an l2 norm.
In this study, the method that calculates the spatial gradient operators across the cell faces between two adjacent cells is extended such that structural orientation information can be incorporated into the inversion. The synthetic gravity examples demonstrate that this method allows models with desired strike and dip directions to be built successfully. Also, the constructed models using this proposed method have sharper boundaries compared to the constructed models that consider each cell as a package with its neighbours for the scenarios in which an l1-norm measure is employed in the regularization term.

Keywords: Gradient operators, inversion, structural orientation information, unstructured tetrahedral meshes.
Micromagnetic Modeling of Thermoremanent Magnetization in Small Natural Pseudo-Single Domain Magnetite Particles
Authors: Beguin Annemarieke , Nikolaisen Even , Fabian Karl
Published: February 2023

Earth and planetary rocks record magnetic variations and are crucial recorders to further our understanding of the formation and evolution of the Earth’s magnetic field. The acquisition and stability of remanent magnetization in rocks are controlled by the magnetization state of magnetic particles. Where the thermoremanent magnetization (TRM) of pseudo-single domain (PSD) magnetite particles probably dominates the natural remanence of many igneous rocks. These PSD particles are therefore important carriers of paleomagnetic information. Nevertheless, the extension of Néel's (1955) elegant analytical theory of single domain (SD) particles to larger PSD particles meets with substantial technical challenges. Understanding the unblocking of energy barriers between energetically favorable domain states is important when predicting the TRM behavior of natural particles. While categorizing different magnetization states is manageable for simple SD particles, it will become increasingly difficult with increasing particle size. Mapping the full energy landscape for PSD particles can be challenging and time-consuming. Here we present an automated process that can categorize all possible local energy minima (LEM) from micromagnetic modeling results. The automated process determines if magnetic states with approximately equal total energy are in the same reversible region. We incorporate calculations of energy barriers between LEMs for an assemblage of natural magnetite particles obtained by focused-ion-beam (FIB) nano-tomography. The technique was tested for a suite of PSD particles from single-vortex to multi-vortex states, where we systematically studied the energy landscape and relaxation time as a function of temperature. To map the energy landscape, LEM and energy barriers between all possible LEM were calculated for temperatures between room temperature and Curie temperature. Combining these results in a statistical model allows for predicting the TRM acquisition of individual particles and isotropic ensembles of equal particles. The results are discussed in terms of the TRM behavior of natural PSD magnetite, magnetic stability, and the implications for paleomagnetic research.
Ecosystem engineers and biogeomorphology of the Mediterranean algal reef Coralligenous
Authors: Basso Daniela , Bracchi Valentina Alice , Bazzicalupo Pietro , Bertolino Marco , Bruno Fabio , Cipriani Mara , Costa Gabriele , D'Alpa Francesco , Donato Gemma , Fallati Luca , Guido Adriano , Muzzupappa Maurizio , Sanfilippo Rossana , Savini Alessandra , Sciuto Francesco , Varzi Andrea Giulia , Rosso Antonietta
Published: February 2023

Coralligenous (C) is a type of Open Frame Reef, characterized by a variable association of calcareous red algae and macroinvertebrates. It is distributed across the Mediterranean shelf below the deepest seagrass meadows and down to the mesophotic zone, with different facies. The Italian project FISR “CRESCIBLUREEF” provided an extraordinary opportunity to explore the development of the Mediterranean C, from inception to present-day morphology and distribution off the SE coasts of Sicily. The spatial extension of C hybrid banks and discrete reliefs over the studied Sicilian shelf controls the hydrodynamics at the seafloor, the habitat biodiversity, and the related carbonate production at the shelf scale. The analyzed C samples, collected at about 36 m depth, had a columnar shape, were Holocene in age, and their development significantly modified the seafloor geomorphology. Our observations confirmed that most of the framework was built by calcareous red algae with an important contribution by bryozoans, with serpulids, molluscs, and rare corals as accompanying components of the sessile macroscopic fauna.The framework was highly porous, with a primary porosity derived from the growth, shape and structure of the skeletal components of both builders and dwellers, and an important secondary porosity derived from bioerosion and other early taphonomic processes involving both skeletonised and soft-bodied organisms, like sponges. During the entire process of framework growth and development, sponges played an important role as mineralization mediators of the autochthonous micrite fraction, which contributes significantly to the framework consolidation. Detrital micrite, rich in fine skeletal remains, is trapped in the primary and secondary cavities and represents an archive for the study of the organisms which are not directly involved in the framework building.
Removing Atmospheric Noise from Interferograms in Mountainous Regions with a Deep Convolutional Neural Network
Authors: Brencher George , Henderson Scott , Shean David
Published: February 2023

Atmospheric errors in interferometric synthetic aperture radar (InSAR)-derived estimates of surface deformation often obscure real signals, especially in mountainous terrain. By taking advantage of the differing spatial characteristics of periglacial landforms and atmospheric noise, we trained a deep convolutional neural network (CNN) to remove atmospheric noise from individual interferograms. Unlike existing corrections, which rely on coarse climate reanalysis or radiometer data, this computer vision correction is applied at the spatial and temporal resolution of the interferogram. We processed Sentinel 1 interferograms of the Colorado Rocky Mountains using the Alaska Satellite Facility's Hybrid Pluggable Processing Pipeline (ASF HyP3) and used the Miami INsar Time-series software in PYthon (MintPy) package to generate low-noise line-of-sight (LOS) velocity maps containing primarily rock glacier and hillslope motion. These maps were combined with noisy short temporal-baseline interferograms to contrive a training dataset. Model performance was assessed using the structural similarity index measure (SSIM) and compared to that of other widely used corrections. We find that our CNN significantly outperforms standard corrections and that previously hidden intraseasonal kinematic behavior is revealed in Colorado rock glaciers. We suggest that insights from external validation against GNSS data and sensitivity analysis could be used to further improve model performance and assess model scalability and transferability. 
Development of the Korean Air Chemistry Modeling System version 2.0 (K_ACheMS v2.0) and its performance of operational mode
Authors: Yu Jinhyeok , Song Chul Han , Kim Min Chan
Published: February 2023

The Korean Air Chemistry Modeling System (K_ACheMS) has been developed to enhance the predictability of PM2.5 in South Korea. In the current version (v2.0) of K_ACheMS, two meteorological models are used to produce meteorological fields. The first model is version 4.1.5 of the Weather Research and Forecasting (WRF) model. The WRF v4.1.5 model is initialized using four cycles (00Z, 06Z, 12Z, and 18Z) of real-time Global Forecasting System (GFS) data from the National Oceanic and Atmospheric Administration (NOAA). The other model is the Regional Data Assimilation and Prediction System (RDAPS), which is the regional operational model of the Korean Meteorological Administration (KMA) based on the Unified Model (UM) developed by the Met Office of the United Kingdom.For air quality model simulations, the Community Multi-scale Air Quality version GIST (CMAQ-GIST) model has been developed based on the CMAQ v5.2.1 model. The CMAQ-GIST model mainly uses a modified version of the Statewide Air Pollution Research Center 07 (SAPRC07TC) chemical mechanism with several important updates, including the following: (i) daytime HONO photo-chemistries; (ii) heterogeneous HO2 reactions; (iii) gas- and aqueous-phase halogen chemistries; and (iv) new yield data for SOA formation acquired from multiple smog chamber experiments conducted under typical conditions of northeast Asia. In order to update chemical initial conditions for the CMAQ-GIST model simulations, a three-dimensional variational (3D-VAR) method is applied to the operational mode of K_ACheMS.Here, we introduce the development of the K_ACheMS v2.0 and present the current performances of the operational mode of K_ACheMS v2.0 by comparing the ground-based observations in South Korea.
Did the North Atlantic Ocean play a role driving Green Sahara conditions during the Late Pliocene and Early Pleistocene?
Authors: Crocker Anya , Jewell Amy , Mitsunaga Bryce , Buchanan Solana , Westerhold Thomas , Röhl Ursula , Xuan Chuang , Russell James , Herbert Timothy , Wilson Paul
Published: February 2023

North Africa is one of the most vulnerable regions on Earth to anthropogenically-driven climate change, but also one of the least equipped to deal with the consequences. Predictions of precipitation levels over the forthcoming centuries diverge, not only in magnitude, but also in the sign of change. One key aspect of this uncertainty comes from the role of Atlantic Ocean sea surface temperatures (SST), which are known to exert a strong control over precipitation in North Africa and are implicated in both the major Sahelian drought of the late 20th century and extreme droughts associated with the Heinrich events of the last glacial period. To better understand how African hydroclimate responds to SST variability across a range of climate states, we reconstruct changes in the ocean and atmosphere through the transition from the Pliocene epoch (when atmospheric CO2 levels were comparable to present) into the cooler Pleistocene. We present data from Ocean Drilling Project Site 659, which is situated in the subtropical North Atlantic beneath the major modern summer Saharan dust plume. Our dust accumulation and X-ray fluorescence core scan data record repeated shifts between highly arid conditions and humid intervals with vegetated or “Green Sahara” conditions over much of northern Africa. The amplitude of these humid events is modulated by both global climate state and variability in solar insolation, with three unusually long intervals of low dust emissions (each lasting ca. 100 kyr) occurring at times when insolation variability was weak. We also present new paired alkenone-derived SST estimates and multi-species planktonic foraminiferal isotope records from 3.5–2.3 Myr ago to explore the role of North Atlantic dynamics in driving African hydroclimate variability. Our records help to develop the environmental framework needed to assess evolutionary outcomes on land and improve our understanding of the mechanisms driving precipitation variability in North Africa.
Could the 2019-20 Australia bushfires or 2020-22 floods be predicted using CMIP decadal prediction?
Authors: Jiang Ze , Choudhury Dipayan , Sharma Ashish
Published: February 2023

Over the past six years, Australia has experienced significant fluctuations in rainfall, including prolonged dry conditions and extensive bushfires, followed by two consecutive years of heavy rainfall in the east. Could such anomalies be predicted many years in advance is the question this study hopes to answer. A prediction framework that combines empirical and physically-based approaches using CMIP decadal prediction, and a novel spectral transformation approach is presented. When tested in a hindcast experiment, this framework shows significant prediction skill for rainfall up to five years in the future across all regions and climate zones in Australia. This framework was used to project from 2018 to 2022, covering the years of bushfires and extreme floods in Australia, as an added blindfolded validation of the prediction approach used. Following this, a blind projection of the precipitation anomalies over the continent for the coming five years is presented, to assess whether the anomalies for the past five years were, indeed, anomalies, or part of a pattern of what can be expected into the future. It is shown that this decadal framework has great potential for predicting whether the next few years will be wetter or drier, extending the predictive accuracy beyond a few months into the future. This can be valuable for managing water resources, prioritizing demands, protecting vulnerable systems, and reducing uncertainty in hydrological decision-making.
Influence of seawater density on pelagic carbonate production
Authors: Zarkogiannis Stergios
Published: February 2023

Planktonic foraminifera are a critical component of global pelagic biogeochemistry, export fluxes, and seawater properties. Calcifying foraminifera cells are profoundly important to biogeochemistry also due to their mass and strong ballasting of particulate organic matter that drives the biological carbon pump and to carbon cycling because of the biochemistry of calcite formation that both removes carbon towards the geological record in the form of carbonate and also produces CO2 for every molecule of CaCO3 produced. My research shows that ocean density exerts a role on planktonic foraminifera biomineralization. Since foraminifera are non-motile plankton glacial/interglacial ocean density fluctuations may cause shell weight changes for buoyancy regulation if foraminifera tend to always maintain certain depths. This newly described mechanism may help to further elucidate the marine carbon cycle. The decreased plankton calcification needs that it foresees during warm periods of lighter waters would remove less alkalinity from the surface interglacial ocean thus leaving it capable to absorb more atmospheric carbon. Furthermore, it is found that foraminifera species calcification intensifies with depth habitat following the increase in water density, offering new hints about the control of the different ocean strata to the carbon cycle.
Apparent stress of moderate sized earthquakes in southern California
Authors: Archuleta Ralph , Ji Chen , Peyton Aaron
Published: February 2023

Using S-wave records at epicentral distances less than 60 km we determine the apparent stress for 62 Mw≥4.5 earthquakes in southern California since 2000. All earthquakes have reliable network moment tensor solutions. We compute seismic radiated energy with two methods: a time domain method by Kanamori et al. (2020) and a frequency domain method by Boatwright et al. (2002). The Kanamori approach (GR) is a modified Gutenberg-Richter in which attenuation and near surface effects are not considered. The Boatwright method uses path attenuation, near surface kappa0, and a station specific radiation pattern. With Boatwright we compute seismic energy 1) with an average radiation pattern (F0) and 2) with station specific radiation pattern (F1). The geometric means of apparent stress are 0.48, 0.40 and 0.57 MPa for GR, F0 and F1, respectively. Apparent stress is independent of seismic moment for these earthquakes. Converting apparent stress to Brune’s stress drop (Andrews, 1986), we find stress drops of 2.1, 1.7 and 2.5 MPa for GR, F0 and F1, respectively. From the perspective of seismic radiated energy, a Brune stress drop is nearly the same as that when using Madariaga (1976) and Kaneko and Shearer (2014) models (Ji, Archuleta and Wang, 2022). The standard deviation of stress drop (log10) is 0.35—almost the same for GR, F0 and F1. Cotton et al. (2013) show the standard deviation from stochastic vibration theory used in ground motion prediction equations is 0.15 for Mw>5.5 earthquakes. Seismic moment/corner frequency methods produce a standard deviation of 0.61, though the magnitude range is larger in some studies. Apparent stress (and consequently stress drop) shows a statistically significant depth dependence (~0.05 MPa/km).
Design of support means for the fixation of biofilms in anaerobic reactors for the treatment of leachate based on principles of biomimetic
Authors: Gomez Zully , Solano Johanna , Rodrigo Maria , Rodrigo Javier
Published: February 2023

The appropriate treatment of leachate is currently one of the priorities of municipalities and large cities for the proper management of solid waste landfills. Leachate management represent a risk for public health and a potentially high environmental impact due to the diverse content of pollutants. Specially in megacities, leachate treatment is extremely important due to the large amount of waste generated by the high demographic concentration. However, current technology used for leachate treatment requires improvements to reduce the pollutant load
The “Doña Juana” sanitary landfill in Bogotá (Colombia) has a physicochemical and biological leachate treatment system. To improve the biological treatment of leachate a better reactors design to minimize the organic load of the effluent discharged into water bodies once they are treated is proposed. In this case study, the efficiency of a supported bed anaerobic reactor for the treatment of Doña Juana landfill leachate has been evaluated. A new design of the support medium for biofilm fixation is proposed considering the characteristics required to increase performance, such as the porosity of the material used, its shape and its general configuration. To improve these designs biomimicry techniques have been used, seeking to imitate elements of nature to adapt them to engineering designs.
Given the versatility of different shapes and configurations that nature offers, biomimicry offers great opportunities to adapt them to functional designs, systems, processes and natural elements. In this work the fundamental bases of this discipline will be considered in the design of the support medium for anaerobic biofilms in the reactor for the treatment of leachate, so as to improve the fixation of the microorganisms responsible for the degradation of organic matter in the proposed medium.
The Heterogeneous Earth Mantle: Numerical Models of Mantle Convection and their Synthetic Seismic Signature
Authors: Desiderio Matteo , Gülcher Anna J. P. , Ballmer Maxim D.
Published: February 2023

Our understanding of the compositional structure of Earth's mantle is still incomplete. Heterogeneity in the lower mantle, documented by both geochemical and geophysical observations, has not yet been explained within a definitive geodynamic framework. Moreover, the origin, geometry and interaction of such heterogeneities remain controversial. In the “marble cake” mantle hypothesis, slabs of basaltic Recycled Oceanic Crust (ROC) are subducted and deformed but never fully homogenized in the convecting mantle. Conversely, MgSiO3-rich primordial material may resist convective entrainment due to its intrinsic strength, leading to a “plum pudding” mantle. While previous geodynamic studies have successfully reproduced these regimes of mantle convection in numerical models, the effects of the physical properties of ROC on mantle dynamics have not yet been fully explored. Furthermore, predictions from numerical models need to be tested against geophysical observations. However, current imaging techniques may be unable to discriminate between these two end members, due to limited resolution in the lower mantle.Here, we model mantle convection in a 2D spherical-annulus geometry with the finite-volume code StagYY. We investigate the style of heterogeneity preservation as a function of the intrinsic density and strength (viscosity) of basalt at lower-mantle conditions. Additionally, we use the thermodynamic code Perple_X and the spectral-element code AxiSEM to compute, respectively, seismic velocities and synthetic seismograms from the predictions of our models.Our results fall between two end-member regimes of mantle convection: low-density basalt leads to a well-mixed, "marble cake"-like mantle, while dense basalt aids the preservation of primordial blobs at mid-mantle depths as in a "plum pudding". Intrinsically viscous basalt also promotes the preservation of primordial material. These trends are well explained by lower convective vigour of the mantle as intrinsically dense (and viscous) piles of basalt shield the core. In order to test these results, we translate the predicted compositional, temperature and pressure fields to seismic velocities for two opposite end-member cases. These two synthetic velocity maps are first analysed and compared in terms of their respective radial correlation matrices and spherical harmonic spectra. Then, we use AxiSEM to simulate wave propagation through the two velocity models. Finally, we discriminate between the two end-members by comparing statistical properties of the corresponding ensembles of synthetic seismograms. Our results highlight how the interplay between primordial and recycled heterogeneities shape the evolution of the thermal and compositional structure of the lower mantle. Furthermore, they provide a framework for relating the style of heterogeneity preservation in the Earth's lower mantle with specific features of the seismic waveforms.
Sense-checking the calibration of the Cluster FGM magnetometer spin-axis offsets using mirror mode waves in the magnetosheath
Authors: Alconcel Leah-Nani , Oddy Timothy , Brown Patrick , Carr Chris
Published: February 2023

The calibrated data from the Cluster fluxgate magnetometer instruments (FGMs) aboard the four Cluster spacecraft are accessible through the European Space Agency (ESA) Cluster Science Archive (CSA). The FGM team at Imperial College – the PI institute that built and supports operation of the magnetometers – has regularly provided validated data to the CSA since its inception. The calibration and validation pipeline is well established and provides measurements at the highest instrument resolution within an uncertainty as low as 0.1 nT. New methods for magnetic field calibration have been proposed in the many years since Cluster’s commissioning. One of these uses mirror mode waves in the Earth’s magnetosheath to determine the spin-axis offsets of an in-flight magnetometer instrument. The FGM team applied this method to the Cluster instrument data during periods when the spacecraft spend a substantive proportion of their orbits in the magnetosheath, typically May-June and October-November. The offsets determined by this method were compared to those determined by the method already integrated into the pipeline. Good agreement was found between the two methods.Due to the limitations in resource, the substantial effort that would be required to change calibration methods and re-deliver over 20 years of FGM data, and the potential impact on literature already published, the team would not recommend retroactive integration of the new method into the pipeline. However, the study provides a useful sense check of the pipeline and the data already delivered, as well as the remaining data to be delivered through to the end of the Cluster mission.
Role of forest thinning techniques towards nature-based climate solutions
Authors: So Kangyu , Rogers Cheryl A. , Sharma Tanisha , Badzioch Rachel , Gonsamo Alemu
Published: February 2023

Forest ecosystems provide many essential services such as climate regulation and carbon storage, which are important for many industries and for global Earth system health. However, forest ecosystems are endangered by ongoing resource exploitation and climate and land cover changes which could lead to the destruction of large quantities of forest carbon stocks and stand inventory. Nature-based climate solutions are gaining traction in recent years, particularly forest thinning techniques like variable retention harvesting (VRH) which promotes forest growth, biodiversity, and ecosystem function. Still, they require an intensive assessment of their contribution to forest structure and enhanced carbon dioxide (CO₂) sequestration, but traditional inventory-based forest monitoring practices are time-, cost-, and labour-intensive and impractical at a national scale. In this study, we implement a comprehensive methodology of forest monitoring that uses a combination of field measurements, digital hemispherical photography, spectroscopic analysis, and unmanned aerial vehicle (UAV)-derived data to derive canopy structure, light environment, and soil biogeochemistry. We evaluated the impact of four different VRH treatments on the leaf area index (LAI), canopy openness, photosynthetically active radiation (PAR) absorbance, biomass, and soil carbon and nitrogen content of an 84-year-old red pine (Pinus resinosa) plantation forest in Southern Ontario, Canada. The VRH treatments included 33% dispersed crown retention (33D), 33% aggregated crown retention (33A), 55% dispersed crown retention (55D), and 55% aggregated crown retention (55A). Our findings show that the VRH treatments were major controls or drivers of seasonal variation in LAI, canopy openness, PAR absorbance, biomass, and soil carbon and nitrogen content. Our study suggests that the dispersed crown retention of 55% basal area is the ideal forest thinning technique to enhance CO₂ sequestration and preserve forest structure and light environment. This study provides insight into the interactions between forest ecosystem dynamics and silvicultural interventions, which is indispensable for improving our understanding of nature-based climate solutions. It will also help outline the framework for monitoring forest structure and CO₂ sequestration on large spatiotemporal scales.
Nitrogen availability as a master control of plant-derived vs. microbial-derived soil carbon accumulation – insights from a novel model
Authors: Yeung Chun Chung , Diaz Yanez Olalla , Bugmann Harald
Published: February 2023

Current models of soil biogeochemistry are facing difficulties to match the observed amount and composition of soil organic carbon (SOC). An important omission is that nitrogen (N) can directly and interactively affect microbial decomposition processes, rather than merely being a nutrient for plant production and a passive subordinate of C flow based on stoichiometric coupling. In the past decades, many litter manipulation studies have shown that SOC stocks do not increase significantly in response to experimental increases of litter C input. Moreover, many N fertilization studies showed that SOC accrual is predominantly driven by changes in heterotrophic respiration instead of litter production; i.e., soluble N directly affects multiple processes such as the activities of various C-cycling enzymes, microbial growth (e.g., via carbon use efficiency, CUE), and necromass production.In order to reconcile empirical insights with simulated patterns of SOC and N dynamics, we developed variants of the Century soil submodel coupled with the stand-scale forest gap model ForClim. We implemented equations to capture neglected processes, including 1) the effect of available N on lignin decomposition; 2) the effect of available N on low C:N substrates (e.g., protein) degradation; 3) the effect of available N on microbial CUE dynamics. We tested the full combination of model variants comprising new or alternative equations against multi-level observational patterns, over large gradients of climate and fertility in Swiss forests.The models reconcile that factors affecting C output (decomposition) predominantly control the site-to-site variation of equilibrium SOC stocks, instead of factors affecting litter C input. We further identified the individual processes essential for shaping the geographical pattern (across different climates, forests, and soil types) of the amount and composition of SOC. We conclude that taking into account the direct effects of available N on microbial processes is essential to improve the realism and accuracy of soil models under global change (i.e., reconciling the mainstream theory of plant-derived vs. microbial-derived SOC accumulation pathways), thus avoiding the need of frequent parameter tuning inherent in “C-centric” models.
Discerning hydrological controls on the behaviour of water surface area changes in oxbow lakes
Authors: Ahmed Joshua , Vasilopoulos Grigorios
Published: February 2023

Oxbow lakes serve as rich habitats for wildlife, natural contaminant filters, and an essential source of sustenance and prosperity for riverine communities around the world. Despite their significance, little is known about the controls on oxbow lake hydrology and the timescales over which they operate. Without an understanding of how these environments currently function, it will be challenging to protect them from the pressures of climate change and land use conversion, thus threatening their ability to deliver the wealth of ecosystem services they currently provide, in the future. Here we present an analysis of the temporal behaviour of 110 recently formed (1984-2022) oxbow lakes in the near-pristine catchments of three Amazonian tributaries and elucidate the hydrological controls on this behaviour using a combination of band-rationing procedures and tropical rainfall data. We demonstrate that water surface areas (WSA) fluctuate annually, with some increasing in size by >60% compared to the year immediately following formation. We found that seasonal and annual rainfall exerted a strong control on annual variations in WSA, while proximity of the lakes to the mainstem was less important. Proximity of the lake to the mainstem became more important where flow could be directly conveyed through tie channels or breaches in the lake plug. Changes in hydro-climate, flow regulation, and land use will alter the dynamism of lake hydrology, thus potentially altering the functioning of lakes in the future.
Longitudinal Variations of Tropical Winds in the UTLS: Aeolus and Strateole measurements of Equatorial Waves and the Walker Circulation
Authors: Banyard Timothy , Wright Corwin , Hindley Neil , Bramberger Martina
Published: February 2023

Tropical atmospheric waves often have fine vertical scales that are difficult to resolve in models and cannot easily be observed using existing satellite or ground-based instruments. These waves are known to strongly influence the driving of the quasi-biennial oscillation (QBO), which is an important source of seasonal predictability in the lower stratosphere, and have important interactions with dynamical mechanisms such as the Walker Circulation. As the first Doppler wind lidar in space, Aeolus provides high resolution measurements of wind on a global scale, including in the hard-to-observe upper-troposphere lower-stratosphere (UTLS) region of the atmosphere. It is therefore a uniquely capable platform for studying these phenomena. Here, we sample ERA5 as Aeolus to produce like-for-like comparisons of resolved and observed wind structures, and co-locate measurements with stratospheric superpressure balloon observations from the Strateole-2 campaign. We analyse Kelvin waves and their interaction with the QBO, including the 2019/20 QBO disruption for which a special Aeolus scanning mode was implemented. We also compare our results with wave spectra from outgoing long-wave radiation (OLR) measurements, and highlight how Aeolus and future Doppler wind lidar satellites can deepen our understanding of the tropical UTLS more generally.
Exploring physics-informed machine learning for accelerated simulation of permafrost processes
Authors: Groenke Brian , Langer Moritz , Gallego Guillermo , Boike Julia
Published: February 2023

Permafrost, i.e. ground material that remains perennially frozen, plays a key role in Arctic ecosystems. Monitoring the response of permafrost to rapid climate change remains difficult due to the sparse availability of long-term, high quality measurements of the subsurface. Numerical models are therefore an indispensable tool for understanding the evolution of Arctic permafrost. However, large scale simulation of the hydrothermal processes affecting permafrost is challenging due to the highly nonlinear effects of phase change in porous media. The resulting computational cost of such simulations is especially prohibitive for sensitivity analysis and parameter estimation tasks where a large number of simulations may be necessary for robust inference of quantities such as temperature, water fluxes, and soil properties. In this work, we explore the applicability of recently developed physics-informed machine learning (PIML) methods for accelerating numerical models of permafrost hydrothermal dynamics. We present a preliminary assessment of two possible applications of PIML in this context: (1) linearization of the nonlinear PDE system according to Koopman operator theory in order to reduce the computational burden of large scale simulations, and (2) efficient parameterization of the surface energy balance and snow dynamics on the subsurface hydrothermal regime. By combining the predictive power of machine learning with the underlying conservation laws, PIML can potentially enable researchers and practitioners interested in permafrost to explore complex process interactions at larger spatiotemporal scales.