University of Hawaii System

We report on new results analyzing Io’s upwelling thermal emission over the range of 0.6 to 22 GHz acquired with the Juno Microwave Radiometer (MWR) in December 2023 and February 2024. The microwave emission spectrum from the surface of Io is retrieved from the MWR calibrated brightness temperatures and represents the vertical temperature gradient in the upper 10s of meters of Io. A large spectral slope (>20K) is observed at all latitudes in the lowest frequency MWR channels suggesting significant endogenic near-surface heating. The spectral slope increases toward the north pole. We compare two end-member model fits to the MWR spectra; a conductive model and a model comprising cooling lava flows. The conductive model implies heat flows ranging from 1-3 W/m2. The alternative model of relatively fresh lava flows or heat vents covered by a cold, highly insulating crusts fits the MWR spectra with flows covering about 10% of the surface with a 3-8m thick crust. We show the regional distribution of sub-surface temperature anomalies with depth, comparing to previously catalogued hot spots, flow units and volcanic centers. We will discuss how model assumptions, such as the microwave loss tangent of the crust material and magma temperature, impact the results.

The idea that Earth’s Moon may host substantial reserves of water ice buried beneath layers of regolith in the polar permanently shadowed regions (PSR) has excited much interest over the past decade. Here, we present numerical modeling in support of a new instrument concept for exploration of the Moon’s PSR: the Cosmic Ray Lunar Sounder, or CoRaLS, under development via a NASA DALI (Development and Advancement of Lunar Instrumentation) grant. CoRaLS is a passive radio-frequency (RF) receiver, tuned to receive direct and reflected radio signals from the subsurface of the Moon. These signals are created via the Askaryan effect, in which high-energy cosmic rays incident on the lunar regolith collide with atomic nuclei and initiate relativistic cascades of charged particles. These particle showers in turn create coherent, linearly-polarized, wideband radio pulses that propagate along the shower path, faster than the phase velocity of light in the regolith, in a Cherenkov cone. These signals can reflect from subsurface interfaces, or scatter from buried objects, thus providing an opportunity to probe the subsurface from orbit. Because this radiation originates from within the regolith, using a passive sensor to detect reflected signals mitigates the effect of strong spurious off-nadir reflections that plague traditional active-source RF systems. We posit that if deposits of relatively pure water ice reside within the upper ~10 m of the lunar surface in PSR, a CoRaLS-style instrument would be uniquely equipped to find it.Radio pulses generated by the Askaryan effect have been observed in Earth’s atmosphere, in terrestrial glaciers, and in salt deposits in the laboratory. They have also been predicted, and should be expected, to develop in the lunar regolith. Our work to date represents the first systematic investigation of the use of this well-established phenomenon in exploration of the lunar regolith, and in particular, prospecting for deeply buried ice in the lunar polar regions.In this presentation, we show the results of a series of 3D finite-difference time domain (FDTD) numerical simulations of the electric field generated by Askaryan-induced radiation from cosmic ray showers in the lunar regolith. Our simulation volumes consist of layered regolith with an embedded pure ice layer at 6 m depth. We vary the thickness of the ice layer and explore the strength and nature of the electric field from direct and reflected Askaryan pulses as observed at a range of positions both on the surface and at a range of angles and elevations above the surface. We find that in these simulations, we can detect reflections from pure ice layers as thin as 10 cm. For thicker layers, we observe distinct reflections, with opposite polarity, from the upper and lower surfaces of the ice layer, that are stronger than and distinguishable from the direct signals. These simulations inform our ongoing work to calculate likely event detection rates for a variety of mission architecture scenarios, as we continue to develop the CoRaLS concept.

The marine dissolved organic matter (DOM) pool is one of Earth's largest carbon reservoirs and a critical regulator of global carbon flux, yet the microbe-molecule interactions governing it remain largely unresolved. In a significant advancement, McParland and colleagues integrate a 3-year, depth-resolved molecular time series of DOM with parallel taxonomic characterization of prokaryoplankton at the Bermuda Atlantic Time-series Study site to examine the coupling between community composition and DOM molecules (E. L. McParland, F. Wittmers, L. M. Bolaños, C. A. Carlson, et al., mSystems 11:e01540-25, 2026, https://doi.org/10.1128/msystems.01540-25). Their analysis reveals high temporal coordination, with approximately 40% of both DOM molecules and microbial taxa exhibiting 12-month periodicities. However, interannual patterns in DOM composition appear more predictable than that of microbial communities, suggesting that functional redundancy, conferred through core metabolic pathways shared across taxa, may act as a stabilizing force for ocean chemistry. By highlighting the endurance of these functional roles, McParland and colleagues provide a framework for incorporating microbial processes into more mechanistic and predictable biogeochemical models.

The trace element composition (Al, Si, P, Ca, and Fe) of suspended particulate matter is presented for the upper 1000 m of the water column along U.S. CLIVAR/CO 2 Repeat Hydrography zonal section I05 (2009) in the South Indian subtropical gyre and meridional section I09N/I08S (2007) in the eastern Indian Ocean from the Bay of Bengal to the subtropical front. Along I09N, high particulate Al and Fe concentrations are found throughout the Bay of Bengal and the northern Indian Ocean indicating significant lithogenic particle loads from river-borne sediment transport and smaller contributions from continental dust flux than current model estimates. Particles have elevated Fe:Al ratios compared to the composition of local shelf sediments, indicating that suspended particulate matter becomes enriched from scavenging of dissolved Fe that accumulates in the oxygen minimum zone in the Bay of Bengal. Along I05, retroflection of the Agulhas Return Current transports African shelf-derived lithogenic particles into the western South Indian basin, resulting in the elevated subsurface concentrations of particulate Al and Fe nearly 3000 km into the interior of the subtropical gyre. Another region of elevated dissolved Fe concentrations and Fe-enriched particulate matter was also observed along I05 in intermediate waters (>600 m) in the subtropical gyre at 32°S between 70 and 74°E, suggesting inputs from a shallow sedimentary or possibly volcanic Fe source to these stations. Comparison of data from the crossover between the I05 and I09N/I08S sections and from the 2007 and 2016 occupations of I09N allows investigation of the temporal variability of basin-scale distributions of particle-associated trace metals with relatively short residence times in the upper water column. The most pronounced differences in trace metal distributions are associated with interannual variability in productive near-coastal and upwelling regions where mixed-layer pFe concentrations vary by a factor of 2–7, whereas Fe and Al in deeper waters and dust-impacted surface waters in oligotrophic regions show significantly less variability. • Shelf sources drive Bay of Bengal particle loads; models may overestimate dust flux • Agulhas Return Current carries shelf particles ~3000 km into the subtropical gyre • Primary production drives interannual variability in particulate trace metals

Abstract An exceptionally heavy rainstorm (the “21·7” Predecessor Rain Event, 21·7PRE) affected Henan Province, China, from 17 to 22 July 2021, coinciding with Typhoon In‐Fa (2021) over the western North Pacific. This study investigates how In‐Fa remotely influenced the 21·7PRE by decomposing atmospheric fields using the multiscale window transform into basic‐scale (>64 days), intraseasonal‐scale (16–64 days), and synoptic‐scale (<16 days) motions. A prominent mid‐to‐lower‐tropospheric anticyclone, located approximately 880 km west of In‐Fa, acted as intermediary circulation linking the typhoon and the rainfall event. The anticyclone channeled moisture into Henan, producing pronounced meridional moisture convergence and supplying ∼64% of the total moisture during the event. Meanwhile, intraseasonal‐scale easterlies between In‐Fa and the western Pacific subtropical high facilitated westward wave‐energy propagation, which intensified an upper‐level divergence zone over Henan Province. This upper‐level divergence, together with local mesoscale cyclone activity, played a critical role in sustaining the extreme rainfall. These results indicate that Typhoon In‐Fa exterted a substantial remote influence on the 21·7PRE through a synoptic‐scale, cold‐core anticyclonic anomaly that mediated wave‐energy propagation and organized moisture transport. The findings highlight a dynamical pathway by which tropical cyclones can affect distant predecessor rain events beyond classical moisture‐conveyor and subtropical‐high paradigms.

Abstract Earth's Energy Imbalance (EEI) is a key metric to quantify climate change. While the ocean absorbs most excess heat, the atmosphere contributes only 1%–2% to the long‐term mean of EEI. However, our analysis of observational data demonstrates that variations in the atmosphere's energy content play a much larger role in interannual variations of EEI, especially in recent years. Including atmospheric energy uptake substantially improves agreement between observed variations in global net radiative flux at top‐of‐atmosphere (TOA) and ocean heat uptake interannually over 2005–2024. It also reconciles a delay between variability of these two quantities, with oceanic storage variability leading net TOA flux anomalies by ∼2 months. The phase shift can be explained by the atmosphere's important role in buffering and redistributing energy during El Niño – Southern Oscillation. The ability to robustly diagnose these relationships is owing to continuous efforts to monitor and improve estimates of the different EEI components.

Abstract Characterizing dust attenuation is crucial for revealing the intrinsic physical properties of galaxies. We present an analysis of dust attenuation in 18 spectroscopically confirmed star-forming main-sequence galaxies at z = 4.4−5.7 observed with JWST/NIRSpec IFU and NIRCam, selected from the ALPINE and CRISTAL ALMA large programs. We fit the emission-line fluxes from NIRSpec and the broadband photometry from NIRCam with Prospector , using both spatially integrated emission and ∼0.6 kpc pixel-by-pixel measurements. We derive the stellar-to-nebular dust attenuation ratio ( f = E ( B − V ) star / E ( B − V ) neb ) from the SED fits and the Balmer decrement with H α and H β . Although individual galaxies show large scatter, the best-fit value is <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>f</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0.5</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.03</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.04</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> , slightly higher than that measured for local starburst galaxies. We find weak correlations of f with galaxy properties, increasing with higher specific star formation rates, younger stellar ages, and more recent star formation. For the range of E ( B − V ) star = 0.009−0.15 mag for in our sample, assuming f = 1 (often adopted in high-redshift studies) instead of f = 0.51 leads to the underestimation of line luminosities and ionizing photon production efficiency ξ ion by ∼3%−36% and ∼4​​​​​​%−46%, respectively. Finally, total stellar masses estimated from spatially integrated SED fits with delayed- τ star formation histories are systematically smaller than the sums of pixel-by-pixel SED fits by a median of ∼0.26 dex, likely because the integrated fits are biased toward luminous young stellar populations.

The extragalactic background light (EBL) fluctuations in the optical/near-IR encode the cumulative integrated galaxy light (IGL), diffuse intra-halo light (IHL), and high-$z$ sources from the epoch of reionisation (EoR), but they are difficult to disentangle with auto-spectra alone. We aim to decompose the EBL into its principal constituents using multi-band intensity mapping combined with cosmic shear and galaxy clustering. We develop a joint halo-model framework in which IHL follows a mass- and redshift-dependent luminosity scaling, IGL is set by an evolving Schechter luminosity function, and EoR emission is modelled with Pop II/III stellar emissivities and a binned star-formation efficiency. Using mock surveys in a flat $Λ$CDM cosmology with ten spectral bands spanning 0.75-5.0$\rm μm$ in the NEP deep fields over about 100$°^2$ with source detections down to AB=20.5 for masking, and six redshift bins to $z=2.5$, we fit auto- and cross-power spectra using a MCMC method. The combined SPHEREx$\times$Euclid analysis recovers all fiducial parameters within 1$σ$ and reduces 1$σ$ uncertainties on IHL parameters by 10-35% relative to SPHEREx EBL-only, while EoR star-formation efficiency parameters improve by 20-35%. Cross-correlations reveal a stronger coupling of IHL than IGL to the shear field, enhancing component separation; conversely, the EoR contribution shows negligible correlation with cosmic shear and galaxy clustering, aiding its isolation in the EBL. Relative to the SPHEREx EBL-only case, the inferred IHL fraction as a function of halo mass is significantly tightened over $10^{11}-10^{14} M_{\odot}$, with uncertainties reduced by 5-30%, and the resulting star-formation rate density constraints extend to $z\sim 11$, with uncertainty reductions of 22-31%.

Many islands are remote and the level of interest in land snails as a component of the global biodiversity conservation agenda is low. The conservation status of many island land snail faunas thus remains at best out of date. However, land snails have an asset that other groups do not-their shells, which can remain post mortem in the shell bank of the soil for many tens or several hundreds of years after the death of the animal. Consequently, numerous island land snails are known only based on empty shells-modern but of uncertain age, and thus escaping the strict requirements for Red Listing extinctions after ad 1500. Many high volcanic islands had extraordinarily diverse and highly endemic land snail faunas, with 50-100 endemic species on land masses sometimes as small as 30-50 km2. 'Devastation' is not a hyperbolic term to describe the fate of many of these island microcosms, with levels of extinction variously documented but not uncommonly in the order of 30-50%, and up to 80%. Historically, loss of habitat-namely deforestation-has been the prime cause of species loss, triggered or accelerated by the introduction of livestock and other feral mammals, which did not directly impact the snails but contributed to habitat loss and degradation. Another wave of extinctions followed the introduction-mostly deliberate-of non-native carnivores (snails and worms), directly preying on endemic snails that had evolved in the absence of such predators. The most infamous of these failed 'biological control' plans was the introduction of neotropical predatory snails, Euglandina spp., to the high islands of the remote Pacific to control the giant African snail pest, Lissachatina fulica, resulting in the extermination of several tens-and probably hundreds-of narrow-range endemic land snail species. Ornamental use of shells and hobbyist shell collecting may have impacted populations of larger, more colourful species. By contrast, climate change has not been documented as having caused any land snail extinctions. Few land snails are charismatic animals and, in view of the broad and deep impact of aliens on devastated natural habitats, in situ conservation of endemic island snails appears to be possible in only rare cases. There are, however, limited initiatives for ex situ conservation that can buy time and offer a glimmer of hope for positive thinking. Concerted and targeted field work to find and collect representative specimens of remaining species is needed in order that knowledge of the existence of these diverse faunas be available to posterity. This article is part of the theme issue 'The biosphere in the Anthropocene'.

Abstract We present and analyze panchromatic (0.35–14 μ m) spectroscopy of the Type II supernova 2023ixf, including near- and mid-infrared spectra obtained 33.6 days after explosion during the plateau phase, with the James Webb Space Telescope (JWST). This is the first in a series of papers examining the evolution of SN 2023ixf with JWST during the initial 1000 days after explosion and monitoring the formation and growth of molecules and dust in ejecta and the surrounding environment. The JWST infrared spectra are overwhelmingly dominated by H lines, whose profiles reveal ejecta structures, including flat tops, blue notches, and red shoulders, unseen in the optical spectra. We characterize the nature of these structures, concluding that they likely result from a combination of ejecta geometry, viewing angle, and opacity effects. We find no evidence for the formation of dust precursor molecules such as carbon monoxide (CO), nor do we observe an infrared excess attributable to dust. These observations imply that the detections of molecules and dust in SN 2023ixf at later epochs arise either from freshly synthesized material within the ejecta or circumstellar material at radii not yet heated by the supernova at this epoch.