A document by Cindy Lim. Click on the document to view its contents.

A document by Gabrielle Tepp. Click on the document to view its contents.

The Urgent Computing Integrated Services for Earthquakes (UCIS4EQ) is proposed as a novel Urgent Computing (UC) seismic workflow that focuses on short-time reports of synthetic estimates of the consequences of moderate to large earthquakes. UC combines High-Performance Computing (HPC), High-Performance Data Analytics (HPDA), and optimized solvers to perform numerical simulations during or immediately after emergency situations, typically within a few minutes to a few hours. Complex edge-to-end UC workflows coordinate the execution of multiple model realizations to account for input and model uncertainties and can provide decision-makers with numerical estimates of the outcomes of emergency scenarios, such as earthquakes addressed by UCIS4EQ. UCIS4EQ is being driven toward operational maturity thanks to the technological and scientific developments within the eFlows4HPC project. Based on containerised micorservices, this workflow is fully orchestrated by the PyCOMPSs workflow manager to automatically prepare and manage physics-based deterministic simulation suites for rapid synthetic results. Through pre-computed and on-the-fly simulations, UCIS4EQ delivers estimates of relevant ground motion parameters, such as peak ground velocity, peak ground acceleration, or shaking duration, with very high spatial resolution. The physics-based engine includes pre-trained Machine Learning (ML) models fed with pre-computed simulation databases, as well as deterministic 3D simulations on demand, providing results in minutes and hours, respectively. The combined results, when well-calibrated, could lead to a new generation of ground shaking maps that complement GMPEs for rapid hazard assessment.To demonstrate the potential use of UC in seismology,  in this work we show the UCIS4EQ simulation of the M7.1 Puebla earthquake that occurred in central Mexico on the 19th of September 2017. With a hypocentre at 18.40ºN, 98.72ºW and 57 km depth, the Puebla earthquake was located about 150 km southeast from Mexico City. Identified as a severe event (VIII) in the Modified Mercalli Intensity scale, it resulted in a total of 370 killed and around 6000 injured, as well as structural damages, downed telephone lines, and ruptured gas mains.

Convective Quasi-Equilibrium (CQE) is often adopted as a useful closure assumption to summarize the effects of unresolved convection on large-scale thermodynamics, while existing efforts to observationally validate CQE largely rely on specific spatial domains or sites rather than the source of CQE constraints—deep convection. This study employs a Lagrangian framework to investigate leading temperature perturbation patterns near deep convection, of which the centers are located by use of an ensemble of satellite measurements. Temperature perturbations near deep convection with high peak precipitation are rapidly adjusted towards the CQE structure within the two hours centered on peak precipitation. The top 1% precipitating deep convection constrains the neighboring free-tropospheric leading perturbations up to 8 degrees. Notable CQE validity beyond a 1-degree radius is observed when peak precipitation exceeds the 95th percentile. These findings suggest that only a small fraction of deep convection with extreme precipitation shapes tropical free-tropospheric temperature patterns dominantly.

Ice shelves are assumed to flow steadily from their grounding lines to the ice front. We report the detection of ice-propagating extensional Lamb (plate) waves accompanied by pulses of permanent ice shelf displacement observed by co-located GNSS receivers and seismographs on the Ross Ice Shelf. The extensional waves and associated ice shelf displacement are produced by tidally triggered basal slip events of the Whillans Ice Stream, which flows into the ice shelf. The propagation velocity of 2800 m/s is intermediate between shear and compressional ice velocities, with velocity and particle motions consistent with predictions for extensional Lamb waves. During the passage of the Lamb waves the entire ice shelf is displaced about 60 mm with a velocity more than an order of magnitude above its long-term flow rate. Observed displacements indicate a peak dynamic strain of 10-7, comparable to that of earthquake surface waves that trigger ice quakes.

How fast a plume can stitch two cratonic nuclei into a stable one remains under-investigated. The Tarim continental block in central Asia is recratonized by a Permian-aged plume and preserves a complete record before, during, and after the plume-driven recratonization. Here we conduct area-depth analysis on seismic reflection data from the central Tarim Basin to date the Phanerozoic deformation. All thrusts and strike-slip faults investigated underwent an early deformation stage (Earliest Ordovician-Middle Devonian), a hiatus stage (Late Devonian-Late Permian), and a newly-discovered deformation stage throughout the Mesozoic. Both deformation stages within Tarim are driven by the subduction and accretion surrounding the block. The Mesozoic finite strains highlight the continuous adjustment as the plume-welded continental lithosphere heals and strengthens. The Tarim plume-driven recratonization concludes not immediately, but ~200 Myr after the plume activity ceased, establishing a characteristic timescale for such events in Earth’s history.

The investigation of upper mantle structure beneath the US has revealed a growing diversity of discontinuities within, across, and underneath the sub-continental lithosphere. As the complexity and variability of these detected discontinuities increase - e.g., velocity increase/decrease, number of layers and depth - it is hard to judge which constraints are robust and which explanatory models generalize to the largest set of constraints. Much work has been done to image discontinuities of interest using S-waves that convert to P-waves (or reflect back as S-waves). A higher resolution method using P-to-S scattered waves is preferred but often obscured by multiply reflected waves trapped in a shallow layer, limiting the visibility of deeper boundaries. Here, we address the interference problem and re-evaluate upper mantle stratification using filtered Ps-RFs interpreted using unsupervised machine-learning. Robust insight into upper mantle layering is facilitated with CRISP-RF: Clean Receiver-Function Imaging using Sparse Radon Filters. Subsequent sequencing and clustering of the polarity-filtered Ps-RFs into distinct depth-based clusters, clearly distinguishes three discontinuity types: (1) intra-lithosphere discontinuity with no base, (2) intra-lithosphere discontinuity with a top and bottom boundary (3) transitional and sub-lithosphere discontinuities. Our findings contribute a more nuanced understanding of mantle discontinuities, offering new perspectives on the nature of upper mantle layering beneath continents.

The use of seismic catalogs enhanced through advanced detection techniques improves the understanding of earthquake processes by illuminating the geometry and mechanics of fault systems. In this study, we performed accurate hypocentral locations, source parameters estimation and stress release modelling from deep catalogs of microseismic sequences nucleating in the complex normal fault system of the Southern Apennines (Italy). The application of advanced location techniques resulted in the relocation of ~ 30% of the earthquakes in the enhanced catalogs, with relocated hypocenters clearly identifying local patches on kilometer-scale structures that feature consistent orientation with the main faults of the area. When mapping the stress change on the fault plane, the inter-event distance compared to the size of the events suggests that the dominant triggering mechanism within the sequences is static stress transfer. The distribution of events is not isotropic but dominantly aligned along the dip direction. These slip-dominated lineations could be associated with striations related to fault roughness and could map the boundary between locked and creeping domains in Apulian platform and basement.

Utilising magnetic field measurements made by the Iridium satellites and by ground magnetometers in North America we calculate the full ionospheric current system and investigate the substorm current wedge. The current estimates are independent of ionospheric conductance, and are based on estimates of the divergence-free (DF) ionospheric current from ground magnetometers and curl-free (CF) ionospheric currents from Iridium. The DF and CF currents are represented using spherical elementary current systems (SECS), derived using a new inversion scheme that ensures the current systems’ spatial scales are consistent. We present 18 substorm events and find a typical substorm current wedge (SCW) in 12 events. Our investigation of these substorms shows that during substorm expansion, equivalent field-aligned currents (EFACs) derived with ground magnetometers are a poor proxy of the actual FAC. We also find that the intensification of the westward electrojet can occur without an intensification of the FACs. We present theoretical investigations that show that the observed deviation between FACs estimated with satellite measurements and ground-based EFACs are consistent with the presence of a strong local enhancement of the ionospheric conductance, similar to the substorm bulge. Such enhancements of the auroral conductance can also change the ionospheric closure of pre-existing FACs such that the ground magnetic field, and in particular the westward electrojet, changes significantly. These results demonstrate that attributing intensification of the westward electrojet to SCW current closure can yield false understanding of the ionospheric and magnetospheric state.

The objective of this work was to understand the suitability and favorability of saline reservoirs for storing hydrogen and ensuring the maximum amount of hydrogen would be withdrawn. We used the Sacramento basin in California to demonstrate the feasibility. We carried out several numerical simulation studies to understand key factors affecting the storage and withdrawal of hydrogen. We combined the results from the numerical modeling to develop a screening and ranking set of criteria for hydrogen storage in saline reservoirs. We then used the screening and ranking set of criteria to rank the formations in the Sacramento basin. We studied five formations in the Sacramento Basin. The numerical simulation study showed that to optimize storage and withdrawal of hydrogen, steeply dipping reservoirs up to 15 degrees, reservoirs with low pressures, reservoirs with good porosity (above 20%), and reservoirs with high permeabilities were most favorable for underground hydrogen storage. This work applies a novel and comprehensive site screening and selection criteria for underground hydrogen storage in saline reservoirs. It builds on a similar work done for carbon dioxide storage and hydrogen storage in depleted gas fields but it considers additional objective of needing to withdraw the stored fluid. The case study in Sacramento Basin can be applied to any other basin.

Seismic tomography models show distinct slab structures at different subduction zones and the dominance of degree-2 mantle structure near the core-mantle boundary (CMB). In order to understand how the observed present-day mantle structure came into being, we employ plate-motion history starting from 140 Ma till the present day in global mantle convection models. We tune model parameters such as the effect of different viscosities in the weak layer below 660, weaker asthenosphere and slabs, internal heat generation rate, Clapeyron slope and density change across 660, density and viscosity of thermochemical piles above the CMB, and model duration, to investigate their effect on the predicted mantle structure. We do a quantitative comparison with the predicted present-day mantle structure from our convection models and the seismic tomography models S40RTS and TX2019S, using the long wavelength geoid anomaly as an additional constraint. We find that distinct and linear slab structures are generated when the asthenosphere is moderately weak and stronger slabs are present. The slabs also need to be strong enough since as they sink into the mantle, they sweep the Large Low Shear Velocity provinces (LLSVPs) underneath Africa and the Pacific and generate plumes along their edges. The shape and location of our predicted LLSVPs and slabs are consistent with those in the tomography models. Some of the predicted plume locations are consistent with the real Earth hotspot locations, although the plume structures do not match those in the tomography models. We find that these predicted plumes are integral in fitting the geoid at the intermediate wavelengths. Introducing a moderate Clapeyron slope (-2.5 MPa/K) at 660 does not drastically affect the predicted slab structure. A stronger negative Clapeyron slope resists mass transfer across 660, causing widespread slab stagnation and stalling of plumes at this discontinuity. The predicted present-day mantle structure and the geoid are similar in thermal or thermochemical cases with slightly dense LLSVPs. However, making the LLSVPs highly viscous or more dense hinders plume generation and degrades the fit to the observed geoid. Through this modelling effort, we attempt to constrain the values of various parameters that have an effect on the predicted mantle structure.

The Negribreen Glacier System on the east coast of Spitsbergen, Svalbard, has been actively surging since 2016, i.e., during the entire lifetime of ICESat-2 (launched in September 2018). The progression of Negribreen's surge throughout the glacier system has resulted in large-scale elevation changes and wide-spread crevassing, which is ideally mapped and analyzed using ICESat-2 measurements processed by the Density Dimension Algorithm for Ice (DDA-ice) (see Herzfeld et al. 2016, IEEE TGRS, and Herzfeld et al., 2022, Science of Remote Sensing).    In this analysis, we quantify how Negribreen has been evolving in its mature surge phase over the course of 2019 and 2020. Using ICESat-2 data, together with airborne field data and Sentinel-1-derived velocity data, we quantify large-scale effects such as elevation-change and mass transfer through the system, as well as smaller-scale effects afforded by high-resolution data products of the DDA-ice such as crevasse characterization, surface roughness and changes thereof.     Results show the expansion of the surge in upper Negribreen where increased crevassing has occurred along with height change rates nearing 30 m/year. In addition, fresh surge crevasses formed along the margin between the surging ice of Negribreen and non-surging ice of neighboring Ordonnansbreen. Finally, increased surge activity found on inflowing glaciers from the Filchnerfonna accumulation zone suggest that surge effects may continue to expand up glacier leading to further disintegration of the ice system with continued mass loss.

During characterization efforts of complex sites and geologies, it is important to estimate material properties efficiently and robustly. We present data and modeling related to the heat of wetting process during spontaneous imbibition, as observed in zeolitic tuff. The heat of wetting is due to adsorption of liquid water and water vapor to an oven-dry core sample and results in an observable temperature rise. The fitting of numerical models to imbibition observations allows simultaneous constraint of single-phase (porosity, permeability), two-phase (van Genuchten m and alpha), thermal (thermal diffusivity), and transport (tortuosity) properties from a single imbibition test. Petrographic analysis informs how microstructure connectivity and pore-lining phases affect the imbibition process. Estimating multiple properties simultaneously from a single test on a core sample helps ensure consistency in interpreted material properties. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525 (SAND2023-07021A).

A document by Axel Perwira Indro. Click on the document to view its contents.

It has been found that wintertime mixed-phase cloud properties can present significant differences based on the degree of interaction with air masses coming from locations with reduced sea ice concentration or high presence of sea ice leads. When these air masses are represented by the water vapor transport (WVT) which can interact with the clouds, the properties of the clouds show contrasting differences with respect to cases where the WVT is not interacting with the cloud, i.e. it is not coupled to the cloud. These findings have been reported first for the analysis of the MOSAiC expedition dataset from 2019 to 2020 in the central Arctic \cite{Shupe_2022,Saavedra_Garfias_2023}. In the present contribution, we expand that analysis to long-term measurements (2012-2022) at the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) at the North Slope Alaska (NSA) site in Utqiaǵvik, Alaska. Based on those 10 years of characterized cloud and  sea ice properties, statistically more robust analysis is performed to support or contradict the MOSAiC results. Furthermore, the statistically richer data set from NSA allows to narrow down cases where the properties or coupled clouds to WVT are substantially dissimilar to decoupled cases. Among those are the increase of liquid water path correlated to a decrease of sea ice concentration and ice water paths which are not exhibiting an influence by sea ice concentration. The thermodynamic phase of the clouds also exposes differences based on the state of coupling among the cloud--WVT--sea ice system. These results are put into consideration for the modeling community since sea ice leads are not explicitly resolved in such models, thus the sea ice leads or polynyas effects to processes responsible for mixed-phase cloud formation/dissipation and thermodynamic phase balance are of considerable interest for the parametrization of energy exchange between the surface and the atmosphere in the Arctic.AGU 2023 Session Selection: A093. Microphysical and Macrophysical Properties and Processes of Ice and Mixed-Phase Clouds: Linking in Situ and Remote Sensing Observations and Multiscale Models.

Based on wintertime observations during the MOSAiC expedition in 2019-2020 \cite{Shupe_2022}, it has been found that Arctic cloud properties show significant differences when clouds are coupled to the fluxes of water vapor transport (WVT) coming from upwind regions of sea ice leads \cite{Saavedra_Garfias_2023,saavedragarfias2023}. Mixed-phase clouds (MPC) were characterized by the Cloudnet algorithm using observations from the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) mobile facility and the Leibniz Institute for Tropospheric Research (TROPOS) OCEANet facility, both on board the RV Polarstern . A coupling mechanism to entangle the upwind sea ice leads via the water vapor transport entraintment to the cloud layer has been proposed to successfully identify differences of MPC properties under and without the influence of WVT. For MPC below 3 km liquid water path was found to be increasingly influenced by sea ice lead fraction whereas ice water path was not significantly different in the presence of sea ice leads. However, the ice water fraction, defined as the fraction of ice water path to the total water path, was exhibiting distinguishable asymmetries for cases of MPC coupled to WVT versus decoupled cases. Mainly, the ice water fractions of MPC coupled to WVT were monotonically increasing with decreasing cloud top temperature, while the decoupled cases show increases and decreases in ice water fraction at some specific temperature ranges. The dissimilar behavior of ice water fraction suggests that WVT could importantly influence the processes responsible for heterogeneous ice formation and solid precipitation, therefore coupled MPC and the ice water fraction was also analyzed as a function of snowfall rates at ground. These characteristics are presented based on case studies where WVT back trajectories are available to have a deeper understanding of the interaction processes with sea ice leads that drives the cloud coupled/decoupled differences. Moreover the statistics of our findings based on the whole MOSAiC wintertime period will be put into  consideration.\cite{von_Albedyll_2023}\cite{Shupe_2022}\cite{saavedragarfias2022}AGU 2023 Session Selection: C014. Coupled-system Processes of the Central Arctic Atmosphere-Sea Ice-Ocean System: Harnessing Field Observations and Advancing Models.

A document by Jakob Christiaanse. Click on the document to view its contents.

A document by William W. Chadwick. Click on the document to view its contents.

A document by Alexander Lipatov. Click on the document to view its contents.

Carbonate rocks frequently undergo remagnetisation events, which can partially/completely erase their primary detrital remanence and introduce a secondary component through thermoviscous and/or chemical processes. Despite belonging to different basins hundreds of kilometres apart, the Neoproterozoic carbonate rocks of South America (over the Amazon and São Francisco cratons) exhibit a statistically indistinguishable single-polarity characteristic direction carried by monoclinic pyrrhotite and magnetite, with paleomagnetic poles far from an expected detrital remanence. We use a combination of classical rock magnetic properties and micro-to-nanoscale imaging/chemical analysis using synchrotron radiation to examine thin sections of these remagnetised carbonate rocks. Magnetic data shows that most of our samples failed to present anomalous hysteresis properties, usually referred to as part of the “fingerprints” of carbonate remagnetisation. Combining scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), highly sensitive X-ray fluorescence (XRF), and X-ray absorption spectroscopy (XAS) revealed the presence of subhedral/anhedral magnetite, or spherical grains with a core-shell structure of magnetite surrounded by maghemite. These grains are within the pseudo-single domain size range (as well as most of the iron sulphides) and spatially associated with potassium-bearing aluminium silicates. Although fluid percolation and organic matter maturation might play an important role, smectite-illitisation seems a crucial factor controlling the growth of these phases. X-ray diffraction analysis identifies these silicates as predominantly highly crystalline illite, suggesting exposure to epizone temperatures. Therefore, we suggest that the remanence of these rocks should have been thermally reset during the final Gondwana assembly, and locked in a successive cooling event during the Early-Middle Ordovician.

In this paper, we present numerical modeling aimed to explain Deep Long Period (DLP) events occurring in middle-to-lower crust beneath volcanoes and often observed in association with volcanic eruptions or their precursors. We consider a DLP generating mechanism caused by the rapid growth of gas bubbles in response to the slow decompression of H\textsubscript{2}O–CO\textsubscript{2} over-saturated magma. The nucleation and rapid growth of gas bubbles lead to rapid pressure change in the magma and elastic rebound of the host rocks, radiating seismic waves recorded as DLP events. The magma and host rocks are modeled as Maxwell bodies with different relaxation times and elastic moduli. Simulations of a single sill-shaped intrusion with different parameters demonstrate that realistic amplitudes and frequencies of P and S seismic waves can be obtained when considering intrusions with linear sizes of the order of 100 m. We then consider a case of two closely located sills and model their interaction. We speculate on conditions that can result in consecutive triggering of the bubble growth in multiple closely located batches of magma, leading to the generation of earthquake swarms or seismic tremors.

Iron meteorites are believed to be fragments of mantle-stripped planetary cores ejected during catastrophic collisions. They are, therefore, a unique class of material, as they constitute the only available samples from planetary cores. An increasing amount of evidence suggests that the tetrataenite-bearing cloudy zones (CZ) in iron and stony-iron meteorites can preserve magnetic records of ancient magnetic activity of their parent bodies over solar system timescales. Tetrataenite islands in the CZ are nanometer-sized ($<$ 200 nm) crystals that form through ordering from precursor taenite islands upon extremely slow cooling through 320 \textsuperscript{o}C. Recent micromagnetic models have shown that such precursor taenite islands form highly thermally stable single-domain (SD) or single-vortex states (SV). In this work we employ a 3D finite-element multi-phase micromagnetic modeling to show that tetratenite inherits the magnetic remanence of taenite precursor when it forms over underlying SD states. When taenite form SV states, nevertheless, tetrataenite reset the precursor magnetization and record a new remanence through chemical ordering at 320 \textsuperscript{o}C. We further assess the thermal stability of tetrataenite islands. We show that in cases where tetrataenite inherits the domain states of its precursor taenite, the origin of the remanence is in fact 10\textsuperscript{5} years older than in cases where tetrataenite resets the precursor SV magnetization, corresponding to records of two very different stages of planetary formation.

The balance of processes affecting electron density drives the dynamics of upper-atmospheric electrical events, such as sprites. We examine the detachment of electrons from negatively charged atomic oxygen (O-) via collisions with neutral molecular nitrogen (N2) leading to the formation of nitrous oxide (N2O). Past research posited that this process, even without significant vibrational excitation of N2, strongly impacts the dynamics of sprites. We introduce updated rate coefficients derived from recent experimental measurements which suggest a negligible influence of this reaction on sprite dynamics. Given that previous rates were incompatible with the observed persistence times of luminous features in sprites, our findings support that these features result from electron depletion in sprite columns.

It is well-established that positive feedbacks between permafrost degradation and the release of soil carbon into the atmosphere impacts land-atmosphere interactions, disrupts the global carbon cycle, and accelerates climate change. The widespread distribution of thawing permafrost is causing a cascade of geophysical and biochemical disturbances with global impact. Currently, few earth system models account for permafrost carbon feedback mechanisms. This research identifies, interprets, and explains the feedback sensitivities attributed to permafrost degradation and terrestrial carbon cycling imbalance with in-situ and flux tower measurements, remote sensing observations, process-based modeling simulations, and deep learning architecture. We defined and formulated high-resolution polymodal datasets with multitemporal extents and hyperspatiospectral fidelity (i.e., 12.4 million parameters with 13.1 million in situ data points, 2.84 billion ground-controlled remotely sensed data points, and 36.58 million model-based simulation outputs to computationally reflect the state space of the earth system), simulated the non-linear feedback mechanisms attributed to permafrost degradation and carbon cycle perturbation across Alaska with a process-constrained deep learning architecture composed of cascading stacks of convolutionally layered memory-encoded recurrent neural networks (i.e., GeoCryoAI), and interpreted historical and future emulations of freeze-thaw dynamics and the permafrost carbon feedback with a suite of evaluation and performance metrics (e.g., cross-entropic loss, root-mean-square deviation, accuracy). This framework introduces ecological memory components and effectively learns subtle spatiotemporal covariate complexities in high-latitude ecosystems by emulating permafrost degradation and carbon flux dynamics across Alaska with high precision and minimal loss (RMSE: 1.007cm, 0.694nmolCH4m-2s-1, 0.213µmolCO2m-2s-1). This methodology and findings offer significant insight about the permafrost carbon feedback by informing scientists and the public on how climate change is accelerating, strategies to ameliorate the impact of permafrost degradation on the global carbon cycle, and to what extent these connections matter in space and time.