A document by Christine Olson. Click on the document to view its contents.

Serpentine carbonation could provide a safe, and environmentally friendly, opportunity to store the amount of anthropogenic CO2 emission necessary to meet the Paris Agreement target and limit global warming to a safe level for humanity. Mineral carbonation relies on the reaction of CO2 with cations abundant in ultramafic rocks (e.g. Mg2+) to form carbonate minerals (\citealp{Kelemen_2019}). Serpentinites are an ideal starting material because they are abundant on or near the Earth’s surface and are rich in Mg2+, which is required to form carbonates, primarily magnesite (MgCO3) that traps CO2 (\citealp{Lackner_1995}). This process stores CO2 in a solid state with no risk of release and has large storage capacity. Even if this technique is promising, it is at a lower stage of readiness and is yet to be applied at the industrial scale.The Ligurian ophiolites (Italy) host several magnesite deposits that formed when deep CO2 was injected into serpentinite lenses through regional faults at 100-200°C and depths of 1-2 km (\citealp{Rielli_2022}, \citealp{Boschi_2009}). These deposits effectively resemble the in-situ storage of CO2 by “natural pilot plants” active millions of years ago, where seemingly the conditions where fine-tuned to best sequester CO2. Thus, they provide a fast lane for understanding the best conditions for serpentinite carbonation.The PRIN 2022 PNRR STORECO2 project (granted by the European Union—NextGeneration EU) aims to understand these conditions through a geochemical, petrological and mineralogical study of the Castiglioncello magnesite deposit (Tuscany, Italy). Developing a deeper understanding on carbonation processes through the study of natural analogues, discussed in this work, we will able also to predict what to expect when CO2 is injected into serpentinites.

Surface charging phenomena on the lunar surface are significantly influenced by topographical features such as craters, boulders, and cavities. This study employs Particle-in-Cell (PIC) simulations to explore how the size of surface cavities affects charging under typical solar wind conditions. Our results show that cavities smaller than the lunar sheath thickness develop strong positive potentials at the depths due to ion currents. However, as cavity size increases beyond the sheath thickness, the influence of ion currents is reduced, resulting in a more moderate potential change inside the cavities. This transition is driven by a shift from surface-charge-dominated ($\sim\!size^2$) to space-charge-dominated ($\sim size^3$) electrostatic structures, as larger cavities allow for greater electron inflow and contribution of the space charge. These findings suggest that both macroscopic and microscopic surface irregularities need to be evaluated according to their spatial scale when considering a global charging environment, which would be significant for understanding dust transport and potential breakdown processes.

The radiation exposure on the lunar surface from galactic cosmic rays and solar energtic particles was predicted with model calculations. The effectiveness of regolith shielding against cosmic radiation was investigated.

A document by Jaclyn Clement Kinney. Click on the document to view its contents.

A document by Mario Arroyo-Solórzano. Click on the document to view its contents.

A document by Timothy DelSole. Click on the document to view its contents.

A document by Katie Spellman. Click on the document to view its contents.

A document by Eshrat Fatima. Click on the document to view its contents.

Moisture source controls on deuterium excess, particularly the logarithmic variant dln,  in Antarctic precipitation are investigated using novel water tracers in a ECHAM6-wiso simulation nudged to the ERA5 reanalysis. The simulation captures the amplitude of seasonal changes in \(\delta\)D and dln of precipitation. There are however some biases that cannot be resolved through adjustments to kinetic fractionation parameters or the model resolution. These may reflect issues in the hydrological cycle representation or the representation of isotopic processes. The simulated dln in Antarctic precipitation reliably reflects moisture source SST: dln shows a higher correlation compared to traditionally defined deuterium excess. Ocean surface relative humidity with respect to SST (RHsst) influences dln during evaporation, however this influence weakens above the surface. 79% of the variance in dln of annual precipitation at Dome C is due to changes in moisture source SST: dln is more sensitive to source SST in inland Antarctica than in coastal regions, making it a robust proxy for reconstructing past SST at the inland ice core sites. The explained variance of dln by source SST for precipitation at Dome C is lower at 28% and 61% for daily and monthly scales (or 59% for daily values during heavier precipitation events); this quantifies the potential to recover moisture source information from high resolution observations of isotopes. Finally, we uncover a previously unknown control on dln in vapour above the Southern Ocean, potentially driven by kinetic fractionation during precipitation re-evaporation. This suggests it contains useful information on precipitation-recycling processes.

A document by Homa Khanahmadi Bafghi. Click on the document to view its contents.

Haoran Liu1, Min Chen1 *1 Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, WI, USA*Corresponding author: Min Chen ([email protected])

The Relative Difference (%) between Solar Maximum and Minimum is highest in the UV range. We calculated the shortwave spectral files used in our models with the SOCRATES radiative transfer code. To account for stellar spectral features sensitive to activity, we designed a new band scheme (see the tables) (https://www.met.reading.ac.uk/~yt910424/home/socrates.php) We used SSI data obtained by the LASP TSIS-1 Spectral Irradiance Monitor (SIM) onboard the International Space Station. The data includes measurements taken during at Solar Minimum (averaged from December 1-7/2019, proposed as the reference spectrum for the upcoming CMIP7, as suggested by Funke et al. (2024)) and the Solar Maximum (averaged June 3-20/2024). For wavelengths beyond 2399 nm, both spectra incorporate the same data as the reference spectrum constructed by Coddington et al. (2023).

The paper analyzes “polar” substorms observed at high geomagnetic latitudes (>70° MLAT) in the absence of substorm-like disturbances at lower latitudes. The analysis is limited to the longitudinal sector of the IMAGE network (~108-114 Mlong), in this case “polar” substorms develop over the Svalbard archipelago. The “polar” substorms are usually observed under quiet geomagnetic conditions, but the question remains open whether “polar” substorms can develop under extremely quiet conditions, when the geoeffective parameters of the space weather are extremely small. We studied 92 “extreme geomagnetic quiet” intervals in 2010- 2020, associated with the intervals of extremely slow solar wind (ESSWs, V < 300 km/s). It is found that ”polar” substorms were observed even under an extremely slow solar wind, however, with the appearance of the negative Bz component of IMF; there were established 32 such events at the longitudinal sector of the IMAGE network in the 17 ESSW intervals (~19% of all ESSW intervals). It is shown that “polar” substorms during ESSW exhibit the main features of ordinary substorms, namely they accompanied by Pi1B geomagnetic pulsations, positive subauroral or mid-latitude magnetic bays, a poleward moving of the westward electrojet and auroras during its expansion phase. Besides, it was found that the most events (~82%) of ”polar” substorms during ESSW were isolated events, developed only in the pre-midnight sector, without substorm disturbances in other longitudinal sectors. Several “polar” substorm events have been studied in detail.

Atmospheric reaeration is a key source of dissolved oxygen in rivers, plays a critical role for assessing aquatic ecosystem health and understanding the mechanisms that support ecological functions. However, traditional water quality models often fail to capture the temporal and spatial dynamics of the reaeration coefficient (k2), thereby hindering accurate predictions of dissolved oxygen concentration distributions. This study employed a recirculating water tank to conduct experiments under various wave and flow conditions, quantitatively analyzing the impact of hydrodynamic factors-such as water depth, flow velocity, and wave action-on oxygen transfer at the air-water interface. The results indicated that as water depth increases and flow velocity decreases, efficiency of oxygen transfer declines. This trend occurs because increased depths and reduced velocities diminish interface disturbance, thereby weakening gas-liquid exchange. Conversely, wave action significantly enhances oxygen transfer, particularly under stronger wave conditions. By integrating gas transfer theory with experimental data, we developed a mapping relationship between k2 and hydrodynamic variables. This framework enabled the development of a multi-parameter dynamic simulation model that integrates hydrodynamics with dissolved oxygen transfer. The model is based on real-time data of hydrodynamic parameters and realizes the dynamic update of the whole domain complex k2, which can accurately simulate the spatial and temporal distribution and transfer of dissolved oxygen under complex hydrodynamic conditions. Driven by dynamic data, the model greatly improves the applicability and accuracy of the traditional mean generalization model, and can be used as an effective tool for predicting dissolved oxygen levels in complex aquatic environments.

Sediment-rich mélange diapirs have been suggested to transport key chemical slab signatures and volatiles to arc magma sources. Here, we assess the phase equilibria, buoyancy and implications for chemical geodynamics of a previously unexplored hydrous shaly-rich mélange (5-10 wt.% H2O) with minor ultramafic component (9:1 ratio) from deep forearc to subarc depths (2-3 GPa and 700-1150°C). Their solidi lie between <645 to ~700°C and upon partial melting, produce dacitic to rhyolitic melts (water-free basis) in coexistence with abundant biotite, pargasitic-amphibole, and quartz (low dense minerals), garnet, and enstatite (rutile/Ti-magnetite ± apatite) that favors the onset of diapirs in thinner mélange channels (<100m) with lower mélange and mantle viscosities in all slab geotherms. At >850°C the low dense mineral abundance decreases, and the mélange loses buoyancy, requiring thicker mélange channels (>100-800m) with higher mélange and mantle viscosities. Thinner and thicker mélanges form smaller (<1 km radius) and larger diapirs (>1 km radius), respectively. While smaller are more susceptible to mineralogical equilibration, lose buoyancy and stall, larger diapirs may sustain buoyancy and relaminate under the arc crust. High LILE/HFSE signatures in most arc lavas may be explained by aqueous fluids and low degree mélange partial melting (<850°C) within the channel or a diapir close to the channel where rutile/apatite/Ti-Fe-oxides minerals are stable, and the presence of garnet impart high LILE/HREE. Although high degree partial melts due to diapirism or slab tears explain dacitic to rhyolitic arc lavas, they would not fractionate HFSEs from LILEs to explain the high HFSE/LILE arc lava signature.

During periods of northward interplanetary magnetic field (IMF), the magnetospheric structure and dynamics are dramatically different compared to the southward IMF case. Previous studies using both observations and simulations have shown that the magnetotail becomes dominated by closed magnetic flux and associated trapped particle populations. In this study, we analyse three intervals of plasma observed in the high latitude magnetotail during a period of prolonged northward IMF, coinciding with observations of cusp-aligned arcs in the polar region. We observe that the plasma is typically continuous with some substructure observed on length scales of 0.5 - 1.5 R$_E$ which may be linked to the substructure observed in cusp-aligned arcs. The plasma characteristics in each of the three intervals studied are similar. The ion and electron densities are on the order of 0.2 - 1 cm$^{-3}$. The electron energies typically vary between 10$^2$ - 10$^3$ eV. The ion energies are higher compared to the electron energies and range between 10$^2$ - 10$^4$ eV. The ion temperatures are on the order of 5 - 18 MK. The speed of the plasma crossing the Cluster spacecraft is between 4 - 21 km/s which is on the order of magnitude of convection speeds in the magnetotail plasma sheet. We tentatively suggest that this may provide supporting evidence for dual lobe reconnection acting to trap plasma within the magneotsphere and resulting cusp-aligned arc formation.

Documenting and characterising past submarine landslides is fundamental to understanding their distribution and frequency through time, and critical to assessing the associated hazard. The widespread availability of marine geophysical data at the active Hikurangi subduction margin, east of Aotearoa New Zealand, provides an excellent basis to map regional trends in landslide occurrence. We present a database that documents mass transport deposits (MTDs) in 30 marine geophysical surveys, encompassing ~45,400 line-km of 2D seismic profiles. We map and characterise 737 MTDs, showing variations in size, location and style of failure, which we attribute to changes in geomorphic setting from north to south. MTDs in the northern Hikurangi margin, characterised by a high taper wedge and seamount subduction, show a broad range in size, with the highest proportion of MTDs displaying blocky or intact internal architecture. The central margin, characterised by lower wedge taper, hosts the most MTDs (51%), albeit with the thinnest (on average) and clustering within interridge basins. The southern Hikurangi margin hosts widespread submarine canyons and the largest (on average) MTDs, based on area and thickness. We demonstrate the importance of seismic archives in providing new insights into MTD preservation and discuss the bias between seafloor geomorphology and subseafloor seismic data in quantifying MTD occurrence. Our findings support the interrogation of the varied and complex causes of submarine landslides along active margins generally, as well as regions prone to cascading geohazards and landslide-induced tsunami.