The mechanical stability of caprock is crucial for the safety and permanence of CO2 storage. In this study, both experimental and theoretical methods are adopted to evaluate the argillaceous (sandstones and shales) and the non-argillaceous (dolostones) caprock's mechanical and physical parameters change, during CO2 mineralized storage. These analyses enable to provide a guideline for the estimation of caprock stability. Methods: Samples of dolostones, sandstones, and shales are directly soaked in the supercritical CO2 solution (at 40 °C and 9 MPa). Firstly, variations of physical and mechanical properties are measured after CO2 soaking. Afterwards, two constitutive equations are constructed to estimate the non-argillaceous and the argillaceous caprocks' mechanical properties. From this, the mechanical-chemical coupling mechanism of CO2 mineralized storage can be characterized. Results: The experiments indicate that the compressive strength of most specimens increases at a 5 MPa confining pressure, while it decreases at a 10 MPa confining pressure. NMR analyses reveal that the porosity of argillaceous caprock showing the largest decrement after CO2 soaking. The micro-pores and meso-pores increase, but macro-pores decrease. This is possibly due to the mineralized particles filling in macro-pores, thereby enhancing the strength at low geo-stress but weakening at high geo-stress. Based on Lemaitre's principle and experimental data, the established constitutive model confirms that the porosity variation reflects the alteration of mechanical strengths. Overall, the physical and mechanical properties of argillaceous caprock are more obviously affected by CO2 mineralized storage than those of non-argillaceous caprock.

Ultra-low velocity zones (ULVZs) above the core-mantle boundary (CMB) are seismically-observed structures that may be related to the liquid outer-core. As ”thin patches” of dramatically low seismic-wave velocity, they are occasionally found in/near simply low seismic-wave-velocity regions or alternatively in/near simply high velocity regions, right at/above the CMB. The causes of their morphology and geodynamics remain unclear, and simulation of high-density melts diverge from observations. We introduce two-dimensional time-dependent Stokes two-phase flow (with melt migration) numerical models to investigate the evolution of high melt-fraction regions affected by CMB-mantle tangential flows, amidst a hot mantle-plume upwelling and an optional neighboring cold downwelling. We find that (a) the participation of cold sources with temperature differences between ~4000 K at the plume-base central regions to <~3900 K at the plume-cooling flanks, separated by horizontal distances of approximately 100 {plus minus}50 km are necessary for dense melts (fractional mass-density difference >+1-2%, <+10%) to attain total-mass quasi-stability, (b) an enhanced tangential-horizontal flow in reverse circulation within the broad plume base (with speeds >1-3 times the lowermost-mantle characteristic flow speeds); are necessary for high aspect-ratio-morphology melt-lenses to be compatible with seismic observations. Stresses exerted on variable CMB topography may arise from lateral motion of localized outer-core rigidity-zone structures. The CMB-mantle tangential flow and/or outer-core interacting with CMB-topography may help generate mega-ULVZs, particularly if they appear along the edges of large low-shear-wave-velocity provinces (LLSVPs) or in/near high-seismic-velocity ”cold” zones. A strong link exists between ULVZ morphology-evolution and the kinematic-thermodynamic heterogeneous environment in-around the CMB.

The characterization of pore-throat structures in tight sandstones is crucial for understanding fluid flow in hydrocarbon reservoirs and groundwater systems. Both thin-section and Mercury Intrusion Capillary Pressure (MICP) offer insights rock petrophysical parameters. However, thin-section analysis is limited by its 2D nature and subjective interpretation, while MICP provides 3D pore-throat distributions, it lacks direct visualization of pore morphology. This study evaluates AI-assisted thin-section image analysis for pore-throat characterization by comparing its results to MICP-derived measurements. A machine learning-based workflow was developed using color thresholding, K-Means clustering, and medial axis transformation to segment pore structures in thin-section images. Throat width, porosity, and permeability were quantitatively assessed against MICP to determine the accuracy and reliability of the technique. The analysis of 26 sandstone samples outlined differences between the two methods. Thinsection analysis showed porosity values from 1.37% to 53.37%, with average pore-throat sizes between 5.63 µm and 30.09 µm, while permeability estimates ranged from 0.01 mD to 344.35 mD. Correlation analysis showed moderate agreement for throat size (r=0.62) and permeability (r=0.61), but weaker for porosity (r=0.32), highlighting the differences in how each method captures pore connectivity. Results demonstrate that the AI-assisted segmentation provides a scalable and reproducible approach but is constrained by thin-section imaging resolution. While MICP remains reliable for permeability evaluation, its comparison with AI-driven image analysis helps assess the reliability of the method. Future research should refine segmentation algorithms, incorporate pretrained data to validate AIderived pore-throat attributes for improved reservoir quality assessment and predictive modeling.

An inverse box model of the Scotia Sea balances the Antarctic Circumpolar Current (ACC) heat, salt, mass and biogeochemical transports up to the 28.00 kg m-3 isoneutral. We construct hydrographic and biogeochemical vertical sections enclosing the Scotia Sea using several datasets up to 2018, and constrain the reference velocity at 1000 m with the Argo floats drift. The results reveal 136.7 ± 1.0 Sv entering through the Drake Passage and 137.9 ± 1.0 Sv exiting through the northern passages (113.6 Sv via the North Scotia Ridge and 24.3 Sv through the Georgia Passage), dominated by the deep circumpolar waters. Salt is near-conservative because of scarce water exchange with the atmosphere, with a freshwater flux gain of only 0.06 Sv, but heat is influenced by the intense ocean-atmosphere energy exchange, with a net loss of 0.065 PW. The combination of physical and biogeochemical processes leads to a total net production  of nitrate and dissolved inorganic carbon (DIC), and a net consumption of alkalinity and dissolved oxygen (DO). Further, we observe a subsurface poleward transfer of water mass and associated properties across the Polar Front, which sustains overall remineralization and DO outgassing in the mode and intermediate waters of the southern sector. The carbon budget is internally dominated by DIC production at 0.16 ± 0.03 Pg C yr-1, accumulating at 0.12 ± 0.03 Pg C yr-1; however, the air-sea exchange is closely balanced despite additional anthropogenic DIC inputs, suggesting that DIC outgasses at faster rates.  

The study of icy moons is of great importance to furthering our understanding of the origins of life in the solar system due to their high liquid water content. While missions like JUICE aim to study these bodies through an observational lens, there has yet to be a mission that probes the subsurface of one of these icy moons. This study details our novel mission plan to explore the Saturnian moon Enceladus. This icy world houses a large subsurface ocean filled with important elements for life, alongside potential catalysts for life to form, such as thermal vents. This mission relies on three main components, an orbiter, a lander, and a drill. We detail the designs for every part of the mission and test a simulated thruster system used for landing as well as the water sampling mechanism of the drill. Our testing of the water sampler highlighted the importance of placing the water sampling mechanism above as few mechanical components as possible to prevent the drill from being unable to resurface, and proved that our sampling design is able to collect water efficiently. Similarly, by using drone propellers to simulate thrust from a descent stage and imitate the lack of an atmosphere, we were able to test the lander concept to gain insight on the thrust required to decelerate the lander and negate horizontal velocity for optimal landing on a surface of unknown material composition. We will analyze the water found in the subsurface region of the planet to gauge the habitability of Enceladus and the potential for finding prebiotic lifeforms on the natural satellite. Our mission aims to further study Enceladus and understand more about icy moons through analysis of surface particles and subsurface ocean water. Our mission will help provide key insights into remote sensing, orbiting, landing, and drilling technologies that will be pivotal to exploring other distant icy moons such as Europa or Titan.

The planktonic copepod, Calanus finmarchicus, typically dominates the zooplankton biomass in deep waters of the Gulf of Maine. The sources and processes controlling the population dynamics of C. finmarchicus in the Gulf of Maine, particularly on the coastal shelves and ledges along the Maine coast, where lipid-rich copepodid stages of C. finmarchicus serve as a primary source of nutrition for planktivorous fish such as herring and mackerel, are not well understood. Knowledge of coastal C. finmarchicus abundance and distribution patterns is particularly important for evaluation of risks associated with right whale foraging in the vicinity of high nearshore densities of fixed fishing gear. Here we document the seasonal patterns and summer distribution of C. finmarchicus copepodid stage abundance in Maine coastal waters of the Gulf of Maine, based on three plankton surveys conducted in July or August in three successive years and concomitant time series of plankton collections at two mid-coast stations. C. finmarchicus copepodid stages CV-CVI, the most energy-rich prey for planktivores, were most abundant in spring (April-May), and again from mid-July through September at the coastal time series station. Abundances of these stages in mid summer (Jul-Aug) were significantly higher, by a factor of 2-47 for stage CV-CVI at offshore coastal stations > 100m depth than shallower nearshore coastal stages. Very few older stage C. finmarchicus were observed in the Damariscotta Estuary at any time of year. Our observations are most consistent with the hypothesis that local coastal production originating upstream from Jordan Basin or the Eastern Maine Coastal Current is the first-order source of C. finmarchicus in the coastal ocean. Abundance of later copepodid stages that develop from this coastal production is diminished in summer by planktivorous predation and possibly by offshore, cross-shelf drift of stage CV entering dormancy. Estimated concentrations of late, lipid-rich copepodid stages based on profiles with a Laser Optical Plankton counter were not sufficiently high to attract right whale foraging behavior inshore of the 100 m isobath; dense layers generally occurred at stations deeper than 150 m.

Radio frequency interference (RFI), particularly human-made RFI such as FM radio, presents a unique challenge to radio astronomy experiments at low frequencies (10 to 200 MHz) such as those for 21cm cosmology and searches for exoplanet auroral emission. Current experiments aim to avoid RFI by building instruments in remote locations. However, as usage patterns change with time and radio bands become more crowded, new sites and mitigation strategies are needed. Here we report efforts toward a survey of the most isolated places on Earth, reflected in measures of human activity, including vessels, transmitter databases, and human censuses. Astronomers have also begun to consider experiments on the radio quiet lunar far side. This work bridges the development of Earth-based and lunar projects for radio astronomy. Over several locations on the planet, the RFI experienced by a space-based instrument, either in low-Earth orbit or on a high-altitude balloon, could be low enough to merit use for a full-fledged 21-cm experiment or as a staging ground for future lunar work. As a precursor to scientific use, we aim to make measurements of the low-frequency radio spectrum in low-Earth orbit. The Radio Background Experiment (RBE) is a compact radio spectrometer built using elements of the EDGES ground-based global 21cm experiment. A prototype of RBE was deployed from the International Space Station as a guest payload on the DORA cubesat in October 2024. The spacecraft re-entered rapidly due to strong solar activity but managed to acquire data indicating healthy functioning of the spectrometer components.

A document by Md Shadman Sakib. Click on the document to view its contents.

Based on over 8 years of moored observation data near the Xisha Islands in the South China Sea (SCS), this study investigated the seasonal variability and vertical distribution of near-inertial waves (NIWs) and internal tides (ITs). It also investigated the impact of mesoscale cyclonic eddies on the downward propagation of NIWs, as well as the mechanism of nonlinear interactions between NIWs and ITs following typhoons. Both NIWs and ITs exhibited significant seasonal variations. Near-inertial kinetic energy (NIKE) was stronger in autumn and winter, while internal tide energy peaked in both summer and winter. Over the entire observation period, ITs were primarily dominated by low modes. In contrast to internal tides, which are dominated by low modes, NIWs exhibit high-mode structures under the influence of negative vorticity. During periods of positive vorticity, the modal structures of NIWs show significant variability. In addition, the study found that cold eddies can also facilitate the downward transfer of near-inertial energy. Taking the autumn of 2011 as an example, under the influence of positive vorticity, NIKE was transmitted downward to the maximum observed depth of 543m, contributing to deep-ocean mixing. The study also revealed that typhoon-induced NIWs, characterized by strong vertical shear, played a dominant role in the nonlinear interactions between NIWs and ITs, leading to the enhancement of nonlinear coupled waves.

Effective assessment of potential climate impacts requires the ability to rapidly predict the time-varying response of climate variables. This prediction must be able to consider different combinations of forcing agents at high resolution. Full-scale ESMs are too computationally intensive to run large scenario ensembles due to their long lead times and high costs. Faster approaches such as intermediate complexity modeling and pattern scaling are limited by low resolution and invariant response patterns, respectively. We propose a generalizable framework for emulating climate variables to overcome these issues, representing the climate system through spatially resolved impulse response functions. We derive impulse response functions by directly deconvolving effective radiative forcing (ERF) and near-surface air temperature time series. This enables rapid emulation of new scenarios through convolution and derivation of other impulse response functions from any forcing to its response. We present results from an application to near-surface air temperature based on CMIP6 data. We evaluate emulator performance across 5 CMIP6 experiments including the SSPs, demonstrating accurate emulation of global mean and spatially resolved temperature change with respect to CMIP6 ensemble outputs. Global mean relative error in emulated temperature averages 1.49% in mid-century and 1.25% by end-of-century. These errors are likely driven by state-dependent climate feedbacks, such as the non-linear effects of Arctic sea ice melt. We additionally show an illustrative example of our emulator for policy evaluation and impact analysis, emulating spatially resolved temperature change for a 1000 member scenario ensemble in less than a second.

Space-based coronagraphs have allowed for improving the methodology for detecting CMEs and predicting interplanetary shock waves and geomagnetic storms. However, studies show not all solar sources of CMEs can be identified. The reasons for this are, first of all, the notable variability of the event parameters. This is especially characteristic of the so-called Stealth CMEs. Such events only have weak signatures in the low corona.Coronal mass ejections go through several phases each of which may have observational features in the X-ray and radio ranges. A series of weak bursts in the soft X-ray range (SXR) characterizes the initiation phase. It is followed by a rapid acceleration phase with maximum ejection speeding up. This shortest phase, as a rule, falls at the X-ray flare’s peak and is accompanied by radio bursts of different types. In this work, we present preliminary results of an analysis of the signatures of a few Stealth-like CMEs in X-ray and radio ranges and data on solar energetic particles within the acceleration phase of the coronal ejection. For the analysis, we use data from the STIX spectrometer for imaging X-rays, RPW radio and plasma wave instrument, and EPD energetic particles detector suite of the Solar Orbiter mission.We show that gradual and prolonged SXR bursts can accompany the formation and development of Stealth-like CMEs in the solar corona. Bursts in the SXR range during the initiation phase are often accompanied by type III radio bursts. The acceleration phase of the coronal cloud is accompanied by type II radio bursts and acceleration of solar energetic particles. These signatures are caused by overcoming critical stability points in the magnetic field configuration, intensive ascent of the flux rope in the corona and the formation of a shock wave at its front.This work is supported by the “Long-term program of support of the Ukrainian research teams at the Polish Academy of Sciences carried out in collaboration with the U.S. National Academy of Sciences with the financial support of external partners”.

This study presents and quantitatively analyzes a new dataset detailing areas affected by ballistic projectiles generated by major explosions and paroxysms at Stromboli. The dataset includes a total of 67 events over ≈150 years, based on an extensive review of historical, observational, and monitoring data. By quantifying distances, directions, and areas affected by ballistic fallout, we provide the necessary data, together with their uncertainty, to produce probabilistic maps of ballistic hazard as presented in a companion study. Our main findings include: (1) 23%-37% of major explosions do not exceed 500 m in their maximum ballistic distance, while 17%-42% of paroxysms remain under 1,500 m; however, 12%-14% of major explosions can exceed 1,000 m, and 29% of paroxysms extend over 2,000 m; (2) sector-based analysis of ballistic distance distribution produces probabilities up to three times lower compared to those based on the maximum distances; (3) directional analysis of ballistic dispersal shows a predominant direction towards the East half-plane (87%) for major explosions and towards the North half-plane (64%) for paroxysms; (4) the average affected area was 6.9e+04 m² for major explosions and 3.6e+05 m² for paroxysms with a mean amplitude of ≈90 degrees for both categories. Notably, major explosions and paroxysms show a continuous distribution of maximum ballistic distance and area affected, suggesting the absence of a net separation between these two categories with respect to this phenomenon. Results highlight the limited influence of uncertainty in reconstructing the dispersal areas and stress the importance of volcanological monitoring of Stromboli’s explosive phenomena

A document by Matthew Pudig. Click on the document to view its contents.

A document by Abdelhamid Ads. Click on the document to view its contents.

A document by Shenyue Jia. Click on the document to view its contents.

In this work, we explore embodied data interaction with the empirical space weather datasets in a mixed reality (MR) environment using extended reality (XR) technologies. Three empirical variables related to the study of solar storms over an 18-year period are shown: SYM-H index data, sunspot number, and ground-based total electron content from the northwest sector of the continental United States. We aim to showcase correlations among these data variables in a novel MR environment and use audio and visual analytics to explore using the XR capabilities to detect correlations. We provide sonification (the use of non-speech audio to convey information) and visual analytics techniques in an MR tool deployed on an MR headset. A human research study involving 54 participants tested the usability and efficacy of the newly developed MR tool on users with no space-science expertise or prior knowledge of the datasets. The results show that even with minimal knowledge of space weather and limited experience with MR environments, the participants were able to identify correlations and begin to understand the scientific context of space weather phenomena. At the CEDAR 2023 conference, we broadened the demographics of the study by studying the responses of space-weather experts in order to more rigorously quantify and assess the potential impact of XR technologies on educational and analysis tools and techniques. Forty-two space science experts gave their feedback about the usability and the potential of this emerging technology as a scientific education and analysis methodology. At the NASA 4th Eddy Cross-Disciplinary Symposium in 2023, we gained a global perspective and feedback from the heliophysics community around the world. At AGU 2024, we intend to present the results collected from space weather experts worldwide, discuss the next steps, and highlight the strengths and challenges of this novel approach to data analysis.

A document by Saman Aryana. Click on the document to view its contents.

• Synthetic, holistic review of tracer Green's function techniques in ocean circulation models • Emphasize common underlying theory and ability to customize tracers to address diverse questions • Illustrate power of ocean tracer Green's functions for diagnostics of transport timescales and pathways