Enhanced Weathering (EW) of silicate rocks is viewed an essential methodology for scaling carbon dioxide removal (CDR) to reach goals of negative global CO2 emissions. EW has an equally important potential for improving agricultural soil, increasing crop yields, and reducing traditional fertilizer use and associated waste. Of all potential silicate raw materials for EW basaltic (mafic) rocks have perhaps the greatest potential, even though the total amount of CDR per unit is less than pure minerals like olivine. Basaltic rocks are widespread compared to other lithologies, are proven to benefit degraded agricultural soils, have significant CDR potential, and minimal negative environmental impacts including heavy metals. Systematic approaches to select basaltic raw material for agricultural and CDR benefits include petrographic and XRD analyses of minerals, XRF and ICP-MS analyses of major and trace elements and grainsize analysis of primary milled material or byproduct material from other aggregate uses. Analysis of commercially available “basalt” shows a wide range in relative quality in terms of primary mineralogy, chemical composition, degree of alteration and metamorphism, achievable grain size, proximity to low carbon transportation and application sites, climate, soil type, and other economic factors. Some products advertised as basalt are dark colored felsic rocks (andesite, dacite) or metamorphosed mafic rocks all of which have lower potential for CDR. These factors limit potential sources of basalt to a small percentage of quarry locations. Mafic, basaltic rocks have SiO2 contents between 45 and 52 percent and vary widely in percentages of mineral phenocrysts– e.g. olivine may range from 0 to >5%, which are also factors in selection of raw material. From an agricultural perspective, analyses of water extractable and Mehlich-3 nutrients reveal values less than the totals of primary unweathered basaltic material; these values increase with degree of EW. Widespread adoption of EW methods for improving soil health will require local and regional crop specific trials and realistic guidelines for application rates and grain sizes that are practical and economic for producers. Characterizing raw material is paramount to instilling confidence in CDR potential and benefits for crops and soil health.

Sub-Plinian eruptions often repeat with short intervals and the magma discharge rate during the eruptions changes. The mechanism that controls the variation in the discharge rate remains unclear, but its understanding is essential for predicting the evolution of explosive eruptions and mitigating the disaster. Here, we petrologically investigated the magma ascent processes during the 1977 eruption of Usu volcano, with four sub-Plinian and two relatively small pumice eruptions. The water contents of the melt inclusions in the first sub-Plinian eruption indicate a pressure of 100-125 MPa with the assumption of water saturation. From the second to the fourth sub-Plinian eruptions, the minimum water content gradually decreased. The crystal size distributions of plagioclase microlite in groundmass show large variations in small size (<1 µm) and these small crystals are inferred to crystallize at low pressure (<40 MPa), confirmed by decompression-induced crystallization experiments. Based on these observations, we infer the following scenario: the magma in the first sub-Plinian eruption ascended from the magma reservoir at the depth of ~4 km; however, the magma stagnated at a shallow conduit and then ascended to the surface during the second to the fourth sub-Plinian eruptions. Moreover, the position of the magma head in the conduit gradually became shallower. The results of this study indicate that the evolution of explosive eruptions during the 1977 eruption of Usu volcano originated from the processes and conditions of both the magma reservoir and the shallow parts of the conduit.

A document by Emily Graham. Click on the document to view its contents.

Tropospheric jet-front systems and intense convection are known to be potential sources of atmospheric gravity waves (AGWs) which can propagate upward. When AGWs reach the height of the coupled thermosphere-ionosphere system they interact with the ionised medium and cause wave-like oscillations known as travelling ionospheric disturbances (TIDs). A strong jet-front system accompanied by intense convection passed through continental Europe between 25 and 29 August 2023. The severe convection

Calving is a critical factor in the dynamics of marine-terminating glaciers, yet its long-term behavior remains poorly understood. Existing models calibrate calving parameters with decadal observational periods and assume they remain constant, effectively overlooking shifts in external drivers like ice mélange. We investigate calving evolution from 1981 to 2021 using a centennial reconstruction of Kangerlussuaq Glacier and identify significant calving regime changes. We show that a shift in the calving parameterization precedes corresponding changes in ice mélange, identified using Landsat data, by four years. This suggests that, while mélange may have a strong impact on calving rates on seasonal timescales, this effect does not persist over multi-decadal timescales. Long-term projections that account for variations in calving parameterization indicate that Kangerlussuaq Glacier will continue to retreat in most scenarios, with ice mass losses ranging from 220 to 1090 Gt, equivalent to 0.61 to 3.01 mm of global sea level rise.

We present a physical and computational analysis of the flocculation of suspended cohesive particles in turbulence by one-way coupling. Our numerical method can separately consider the cohesion, lubrication, and direct contact forces for each pair of particles, thereby allowing us to conduct a detailed analysis of their influence on the flocculation process in turbulence. We first test the numerical approach in the two-dimensional cellular flow which consists of Taylor-Green vortices and investigate the binary interaction of cohesive particles. Further, we numerically investigate the flocculation of suspended cohesive particles with significant surface roughness in homogeneous isotropic turbulence and analyze the temporal evolution of the average sizes. Stronger cohesion and weaker turbulent shear yield larger flocs. The increase of the Stokes number limits the growth of flocs. The influence of the particles' roughness on flocculation is compared. Larger roughness yields a smaller equilibrium floc size while it does not affect the flocculation rate.

Changes in wave climate will impact coastal zones through changes in sediment supply via longshore sediment transport (LST). Estimating these changes is challenging as biases and uncertainty in wave climate projections lead to uncertainty in LST projections. This paper compared wave climate and LST projections derived from two iterations of the Coupled Model Intercomparison Project (CMIP), as well as the implications of using wave climate bias correction in these projections, for the end of the 21st century under high emission scenarios. LST was simulated in a process-based model calibrated against data from an artificial sand bypassing system. Bias correction improved the representation of the wave climate, including extremes, and reduced the uncertainty between CMIP iterations and climate models. While bias correction did not significantly change the projected mean LST, it reduced the spread of model ensembles by 20% and 10% for CMIP5 and CMIP6, respectively. Both CMIP5 and CMIP6 suggest a reduction of LST in the future for the study area. However, CMIP6-derived projections show: 1) 50% less uncertainty in wave forcing conditions; 2) greater consistency in LST projections between ensemble members; and 3) double the reduction in LST. This reduction is attributed to changes in the balance between modal and extreme waves and changes in wave direction. This contribution highlights the value of a bias-corrected model ensemble, and the improvement in CMIP iterations, in providing robust projections of future wave climate change and its impacts on regional coastal processes.

Internal tides are generated in the stratified ocean interior by the interaction of barotropic tidal currents with rough bathymetry. Low-vertical-mode internal tides can transport energy thousands of kilometres from their generation site, and how and where they eventually lose this energy to turbulent dissipation and mixing is of importance to the oceanic energy budget. A potential mechanism for the transfer of energy from the low-mode internal tide to smaller scales is superharmonic generation, whereby internal tides in equatorial regions and non-uniform stratification excite waves with shorter wavelengths and higher frequencies. Here, we use a realistic global ocean model to investigate an enhanced superharmonic tidal signal in the equatorial Pacific Ocean. Using existing theory, we demonstrate that the superharmonic amplitude is consistent with nonlinear self-interaction of the original 'parent' baroclinic tide, providing strong evidence for an energy pathway from the mode-1 M2 internal tide to smaller horizontal scales and higher frequencies.

The distance over which planktonic larvae are dispersed and the variability within that dispersal distance are important for understanding gene flow and persistence of species with planktonic larvae in the coastal ocean. The breadth of spatial and temporal scales that can be important to dispersal in shelf seas makes direct observations of larvae, and thus these statistics difficult - instead, we often use numerical simulations of circulation to estimate the statistics of larval dispersal. However, meroplanktonic life histories are most common in coastal regions where drifter-based estimates of circulation are sparsely distributed, making validation of these numerical simulations quite difficult. We use a novel technique to validate climatological mean and standard deviation of dispersal distance at a global scale by drawing on the tens of thousands of sparsely distributed drifter observations on the shelf. Numerical dispersal estimates were made using Lagrangian particle trajectories calculated with circulation fields from a 1/12{degree sign} global physical model and were validated against drifter data from the Global Drifter Program (GDP). The median dispersal distance of a climatological ensemble of numerical drifters released from a single location were found to match GDP drifter estimates quite well (with a mean deviation of 0.2%), while model estimates of dispersal were shown to underestimate the diffusivity of GDP drifters by 30 to 50%. Our results indicate that while global numerical estimates of dispersal statistics provide a close approximation of median dispersal distance in the coastal ocean, these numerical simulations underestimate the overall variation present in the coastal ocean.

A document by Mark B. Moldwin. Click on the document to view its contents.

A document by Parnia Shokri. Click on the document to view its contents.

The seasonal variability of phytoplankton vertical distribution is investigated in the South Pacific where observations are scarce and scattered. We used 13 BioGeoChemical-Argo floats deployed across diverse oceanic environments. The seasonal latitudinal displacement of the Tasman front induces transitions from mesotrophic to oligotrophic conditions. This shift results in Chlorophyll-a concentration vertical distribution changing from bloom types to Subsurface Chlorophyll Maxima (SCM) types, with intermediate hybrid types between these extremes. Such hybrid profiles frequently occur in the equatorial Pacific, highlighting a large-scale pattern rather than local island mass effect. In oligotrophic regions, seasonal variations of light availability and stratification dynamics below the mixed layer likely relate SCMs to an increase in carbon biomass or photoacclimation. A biomass increase is frequently observed, contrary to previously reported, suggesting that subsurface phytoplankton production may have been largely underestimated. This calls for further observations of the water column in these remote undersampled open ocean areas.

The number of objects orbiting the Earth will significantly increase with the deployment of large constellations of small satellites, along with the launch infrastructure needed to support it. Upon reaching the end of service life, most satellites and upper stages of launch vehicles in low-Earth orbit (LEO) burn up during reentry in the mesosphere. This high-altitude influx of chemical species such as Aluminum, which is dominant in aerospace structures, raises questions about the long-term impacts of burning anthropogenic objects during atmospheric reentry. The polluting potential of the said activities encompasses fluctuations in radiative forcing, impacts in ice nucleation, cloud condensation, and stratospheric ozone concentrations. We present a methodology that resorts to large-scale Molecular Dynamics simulations to infer the behavior upon reentry of a typical small satellite with an Aluminum-rich structure. As a first-principle informed method for modelling physical and chemical interactions, it allows to preform simulations of increasingly larger domain sizes at atomic scale, emulating the behavior of up to hundreds of thousands of atoms to compute the oxidation yield and particle size distribution. The full-scale scenario results are inferred from the atomic scale, showing that the byproduct particle size follows a lognormal distribution centered in the nanoparticle regime (nucleation/Aitken mode).This tool can provide more accurate inputs to atmospheric models aiming at estimating the global impact of reentries from LEO in the atmosphere. The use-case is focused in the oxidation of Aluminum upon reentry, and forecasts are made and compared against the contribution from micrometeoroids entering atmosphere.

Ocean eddies are crucial around the Antarctic margin and there is evidence that they facilitate cross-slope flow of warm water, potentially contributing to ice shelf melt and accelerating sea level rise. However, because eddies around Antarctica are smaller than in other parts of the ocean, these eddies are also more difficult to observe and model. Here we compare the representation of eddies around the Antarctic continental margin in ocean-sea ice models at two different resolutions (1/10⁰ and 1/20⁰), and examine their link to local circulation features. Compared to the 1/20⁰ model, the 1/10⁰ resolution model has stronger shelf currents, especially in East Antarctica, but lower eddy kinetic energy (EKE). On a seasonal timescale, sea ice, EKE and current strength co-vary, with strong correlations on the shelf between current strength and EKE. Current strength and EKE both exhibit prominent seasonal hysteresis, where winter sea ice growth precedes a decline in EKE and current strength, and springtime sea ice decline leads an increase in EKE and current strength. The seasonal link between eddy energy, sea ice and current strength is stronger on the continental shelf than on the slope, and is amplified under higher model resolution. Given how strongly sea ice modulates eddy growth in higher resolution models, a decline in sea ice extent under climate change could greatly increase the projected EKE in models, which could have implications on cross-slope heat transport and thus Antarctic ice shelf melting.

The flux of galactic cosmic rays (GCRs) is modulated by solar activity on different time scales. This is often described with the force-field approximation via the single variable parameters of the modulation potential, which formally corresponds to the average rigidity loss of GCR particles in the heliosphere. The force-field approximation is usually assumed to work properly only for periods of a solar rotation (27 days) or longer. However, daily values of the modulation potential have been constructed based on ground-based neutron monitor (NM) data suggesting that this approach might work reasonably well also on shorter time scales. Here we check this by simulating the daily GCR proton fluxes using the force-field approach and the daily modulation potential reconstructions, and confronting them with the daily proton-flux measurements by the AMS-02 onboard the International Space Station. A polynomial regression between the simulated and measured fluxes is proposed for longer-term analyses and interpolations. For mid-rigidities from 3\,–\,11 GV, the agreement is accurate within $\pm 1\%$ and slightly worsens towards higher rigidities, likely because of smaller statistics. We also found a lingering solar-cycle trend at lower energies and the effect of the solar magnetic field polarity. These findings can be used for the utilization of the force-field approach for short-term variations.

The Geosciences Students Excelling in Real, Vital Investigations with Community Engagement (GEO SERVICE) program at the University of Louisiana at Lafayette aims to increase awareness and interest in geoscience careers among 8th-12th grade and undergraduate students. Funded by the NSF GEOPAths STEM Education Grant Program, GEO SERVICE addresses the gap in student exposure to geoscience pathways through immersive, hands-on learning experiences. Our program targets 8th-12th grade and early undergraduate students, engaging them in research-based, community-focused Service-Learning Projects (SLPs) that address local environmental challenges, such as coastal wetland loss and flooding in south Louisiana and areas along the gulf coast. These projects are designed to foster sustained interest in STEM careers by providing practical, career-relevant experiences. Participants in the program collaborate with university faculty, graduate students, undergraduate and community mentors to analyze diverse datasets and apply geospatial technologies. For instance, during the "Rising Waters" summer workshop, 8th-12th grade students learn about remote sensing techniques and urbanization effects on flooding through activities like kite-based data collection, flying drones and their sensors, and Landsat satellite imagery analysis. The workshop culminated in students creating digital Story Maps that integrated their findings, which were presented to their peers. The GEO SERVICE program not only equips students with essential skills such as data interpretation, effective communication, and project planning but also aims to improve geoscience literacy among diverse communities. By creating a bridge from middle and high school to college, the program seeks to increase the number of students pursuing geoscience majors and careers, thus addressing future workforce needs in STEM fields. This presentation will highlight the program's structure, activities, and initial outcomes, demonstrating the impact of community-engaged learning on student recruitment and retention in geosciences. Our evaluation of the past three summer workshops will inform future iterations, ensuring continuous improvement and alignment with educational and workforce demands.  ract content goes here

The Amazon River mobilizes one of the largest fluxes of particulate organic carbon (POC) from land to coastal ocean sediments, playing an important role in the long-term sequestration of biospheric organic carbon in the ocean. Ramped oxidation (RPO) analyses of suspended sediments collected from the Amazon River mainstem, Solimões River, Madeira River and Tapajós River presented an opportunity to parse riverine POC by thermal reactivity, extract activation energy distributions associated with the biomolecules in these samples, and characterize the molecular diversity of POC across the floodplain. The RPO data show that POC from the Amazon River Basin spans a wide but constant activation energy range across samples, suggesting that the degradation state of POC is relatively constant across tributary locations and depths within the mainstem. Coupling the thermal reactivity data to stable and radiocarbon isotopic analyses shows that ca. 85% of mainstem POC derives from a range of partially degraded terrestrial sources, likely organic matter from mineral soil horizons. In agreement with earlier assessments of POC across the Amazon River Basin, ca. 10% of the riverine POC flux is fresh vegetation and up to 5% of it is petrogenic organic matter. We hypothesize that the higher activation energy POC pools are more likely to survive the journey from the river basin to the coastal Atlantic Ocean, and end with the argument that expanded RPO analyses of samples across the Amazon river-to-ocean continuum would provide an opportunity to test such hypotheses linking POC composition to long-term fate.