We report on the proof-of-concept of a low-mass, low-power method for collecting micron-sized sulfuric acid aerosols in bulk from the atmosphere of Venus. The collection method uses four wired meshes in a sandwich structure with a deposition area of 225 cm2. It operates in two modes: passive and electrostatic. During passive operation, aerosols are gathered on the deposition surface by aerodynamic force. During electrostatic operation, a tungsten needle discharges a high voltage of −10 kV at the front of the grounded mesh structure. The discharge ionizes aerosols and attracts them to the mesh by Coulomb forces, resulting in improved efficiency and tentative attraction of submicron aerosols. We describe the instrument construction and testing in the laboratory under controlled conditions with aerosols composed of 25%, 50%, 70%, 80%, 90% and 98%* concentration by volume of sulfuric acid, the rest water. We demonstrated the following: (i) both modes of operation can collect the entire range of sulfuric acid solutions; (ii) the collection efficiency increases steadily (from a few percent for water to over 40 percent for concentrated sulfuric acid) with the increased concentration of sulfuric acid solution in water in both modes; (iii) the relative improvement in the collection of the electrostatic mode decreases as the sulfuric acid concentration increases. We also demonstrated the operation of the instrument in the field, cloud particle collection on Mt. Washington, NH, and crater-rim fumaroles' particle collection on Kīlauea volcano, HI. The collection rate in the field is wind-speed dependent, and we observed collection rates around 0.1 ml•min−1 in low wind environments (1-2 m•s −1), and around 1 ml•min−1 in stronger wind (7-9 m•s −1).

Mesoscale Convective Systems (MCSs) are crucial in shaping large-scale tropical circulation and the hydrological cycle, particularly in Northwestern South America (NwSA), a region marked by complex terrain and significant MCS activity. Understanding MCSs in NwSA is vital due to their impact on precipitation patterns and potential for severe weather events. To enhance this understanding, the ATRACKCS algorithm was developed for tracking convective systems, utilizing precipitation and brightness temperature datasets. This research focuses on documenting the spatiotemporal variability of MCS occurrence, life cycle, and movement. Notably, MCS hotspots were identified to the west of the major orographic features in the region, with maximum occurrences at night, contrasting with the region's typical afternoon peak in land convection. MCS movement is also heavily influenced by topography, with higher velocities on the eastern (windward) side of the Andes compared to velocities on the western (leeward) side. MCSs generally move westward, driven by easterly winds, but this pattern is not consistent throughout the year or region. Northward movement is predominant to the west of the Andes, while southward movement is observed to the east. These seasonal and regional movement variations are linked to factors such as the intertropical convergence zone position, moisture availability, topography, and low-level jets. This research underscores the complexity of MCSs in NwSA and emphasizes the need for detailed studies on the atmospheric environment shaping these systems. Additionally, it provides a robust 21-year MCS database for NwSA and an advanced tracking tool for research in various geographic contexts and impact areas.

We write as a group that include authors, chapter scientists, and review editors of the Intergovernmental Panel on Climate Change (IPCC)'s most recent assessments of sealevel and ice-sheet changes, as well as scholars of the IPCC process and developers of tools to communicate IPCC sea-level projections.The IPCC is a United Nations (UN) body established to assess the science of climate change. By providing governments with a common, rigorously reviewed, scientific fact base for policy discussions, rather than leaving scientific disagreements to play out in more politicized, policy-making venues, it plays a critical role in global climate governance.Unfortunately, a recent UN secretariat technical brief on sea-level rise attempts to update the IPCC Sixth Assessment Report (AR6)’s assessment without the benefits of the IPCC’s established assessment processes. In concluding that “since the publication of the IPCC AR6 [report] in 2021, a growing number of scientific studies on ice-sheet loss are raising alarm among scientists that future [sea-level rise] could indeed be much larger and occur sooner” than AR6 assessed, it misunderstands the IPCC AR6 presentation of future sea- level rise and presents an unbalanced perspective on literature published since AR6.

The impacts of El Niño-Southern Oscillation (ENSO) on salinity and alkalinity in an equatorial coral reef lagoon (Kanton) are investigated using water samples collected in 1973, 2012, 2015, and 2018. A simple advective-diffusive model is developed to aid in the interpretation of the sparse observations and make estimates of net ecosystem calcification (NEC) rates. Salinity and alkalinity variations in Kanton lagoon are primarily driven by ENSO variations in precipitation. During non-El Niño years (1973, 2012, 2018), salinity increases from the ocean (35.5 psu) to the back of the lagoon (38 psu) because evaporation exceeds precipitation and water resides in the back of the lagoon for ~180 days. At the onset of the 2015-16 El Niño the back of the lagoon is only ~1 psu saltier than the ocean because precipitation had begun to exceed evaporation. The model suggests that during El Niños, when precipitation exceeds evaporation, the back of the lagoon is less salty than the ocean (30 – 32 psu). Alkalinity variations in the lagoon are primarily due to dilution or concentration driven by the ENSO variations in precipitation and NEC that causes an alkalinity deficit of ~250 micromoles/kg in the back of the lagoon. NEC rates in the early stages of the 2015 – 2016 El Niño were ~10% lower (4.7 mmol/day) than in the non-El Niño years (5.2 – 5. 5 mmol/day). The NEC rates and coral cover indicate that Kanton Lagoon has recovered from the complete loss of coral cover during the 2002-03 El Niño.

The Beaufort Gyre is an important feature of the Arctic Ocean. By accumulating or releasing freshwater, it influences ocean properties both within the Arctic and as far as the North Atlantic. Yet, its future remains uncertain: the gyre could strengthen as sea ice declines and allows increased wind stress on the ocean, or weaken along with the Beaufort High pressure system. Here, we provide a first evaluation of the Beaufort Gyre in historical and climate-change simulations from 27 available global climate models. We find that the vast majority of models overestimate the gyre area, strength, and northward extent. After discarding the models with too inaccurate a gyre and its drivers – namely, the sea ice cover and Beaufort High – we quantify changes in the Beaufort Gyre under two emission scenarios: the intermediate SSP2–4.5 and the high-warming SSP5–8.5. By the end of the 21st century, most models simulate a significant decline or even disappearance of the Beaufort Gyre, especially under SSP5–8.5. We show that this decline is mainly driven by a simulated future weakening of the Beaufort High, whose influence on the Beaufort Gyre variations is enhanced by the transition to a thin-ice Arctic. The simulated gyre decline is associated with an expected decrease in freshwater storage, with reduced salinity contrasts between the gyre and both Arctic subsurface waters and freshwater outflow regions. While model biases and unresolved processes remain, such possible stratification changes could shift the Atlantic-Arctic Meridional Overturning Circulation northward.

Evaluating the efficacy of climate mitigation measures requires quantifying urban greenhouse gas (GHG) emissions. Both anthropogenic and biogenic GHG fluxes are important in urban systems, and disaggregation is necessary to understand urban GHG fluxes. One vegetative community common in these urban environments is turfgrass, and the Vegetation Photosynthesis and Respiration Model (VPRM), commonly used to create prior fluxes necessary for determining urban carbon dioxide (CO2) fluxes via inversion modeling, had assumed this Plant Functional Type (PFT) to be dormant in the winter. Two urban turfgrass flux towers in Indianapolis show a photosynthetic drawdown in the winter. We use data from these towers to create a new turfgrass PFT parameter set for VPRM. The new turfgrass PFT enables VPRM to simulate photosynthetic activity during winter, unlike the previously used parameter sets for grassland. We also find that less-managed lawns like cemeteries need different parameters than heavily managed lawns like golf courses, and seasonally changing parameters are needed to model these turf lawns. We use the revised VPRM to explore daily and seasonal variability in turfgrass fluxes and their impact, integrated across the city, on urban ecosystem CO2 fluxes. This study illustrates the importance of representing turfgrass as a unique PFT when quantifying urban GHG fluxes and the biases resulting from misrepresentation.

Many planets, including Earth, possess a global dipolar magnetic field. To diagnose the interior source of the dipolar field, researchers usually adopt a dipole model consisting of six parameters to fit the observed dataset of the magnetic field. However, the simultaneous fitting of these parameters often leads to multiple local optimum parameter sets. To address this fitting dilemma, a current loop model was recently developed by Rong et al.(2021). This technique can separate and invert the loop parameters successively. Here, we further show how this technique can be reduced and modified to fit a dipole model. The applications of this reduced technique to the model of the International Geomagnetic Reference Field and the Martian crustal field model highlight its unique ability to diagnose both the planetary global dipolar field and the local crustal field anomaly, a capability that sets it apart from existing methods. This technique’s potential impact on geomagnetism and planetary magnetism is significant, given its unique ability to diagnose both the planetary global dipolar field and the local crustal field anomaly.

Deep (>20 km) crustal seismicity is typically associated with cold Precambrian lithosphere. However, previous studies have reported that the depth above which 90% of seismicity occurs (D90) in the Southland region of New Zealand is 30-35 km, even though it is situated in relatively young Mesozoic crust at the eastern edge of the transpressive Pacific-Australian plate boundary. To examine this unusual lower crustal seismicity further, we deployed 19 short period seismometers between October 2022-2023 through the Southland Otago Seismic Array (SOSA). Supplemented by the permanent GeoNet network and an ongoing array to the west in Fiordland, SOSA provided a station spacing of ~30 km across this 150 km wide region. In total, SOSA recorded 85 events in and around Southland. These events are not uniformly distributed, with an abrupt decrease in seismicity east of Fiordland. We also identified six spatial-temporal clusters of elevated seismicity across eastern Fiordland and Southland. The distribution of SOSA event depths confirms the presence of lower crustal seismicity in Southland (D90 = 32 km). This D90 estimate is significantly deeper than suggested by event depths to the north in Otago (D90 = 14 km). Using 1D lithospheric strength profiles, we suggest that the embrittlement of Southland’s mid-lower crust reflects the emplacement of mafic terranes in this region during Mesozoic subduction at the Gondwana margin. Our study therefore highlights that a mafic lower crust can lead to deep seismicity within a region undergoing transpression.

Flooding poses a significant threat to infrastructure, ecosystems, and communities, exacerbated by climate change and urbanization. Effective flood governance requires coordinated action across sectors, yet current approaches remain fragmented and fail to address critical socio-environmental factors shaping collaboration. Despite increased awareness, the complexity of flood governance—driven by diverse stakeholders, varied risk perceptions, and uneven institutional capacities—remains a challenge. This study addresses these gaps by applying network analysis and Exponential Random Graph Models (ERGMs) to examine relationships among flood governance actors in the Beaumont-Port Arthur region. Our unique approach analyzes both the structural features of governance networks and the role of shared perceptions of flood risk drivers and impacts, offering insights into socio-environmental factors shaping collaboration. The paper identifies the structural characteristics of governance networks across flood preparation, mitigation, response, and recovery phases, while evaluating how perceptions of risk influence network ties. Our findings reveal significant governance gaps in addressing socio-economic and ecological impacts, with lower network connectivity in these areas. Conversely, infrastructure considerations play a central role in fostering partnerships, particularly in long-term planning efforts. Organizations with aligned perceptions of key drivers, such as infrastructure and precipitation risks, form more cohesive and responsive networks. These results emphasize the need for inclusive, adaptive governance frameworks that integrate diverse perspectives and strengthen local engagement. This study provides valuable insights for policymakers, offering pathways to enhance flood resilience by addressing the socio-environmental dynamics shaping collaborative networks.

The National Water Model (NWM) is a key tool for flood forecasting and planning and water management. Key challenges facing NWM include calibration and parameter regionalization when confronted with big data. We present two novel versions of high-resolution (~37 km2) differentiable models (a type of physics-informed machine learning): one with implicit, unit-hydrograph-style routing and another with explicit Muskingum-Cunge routing in the river network. The former predicts streamflow at basin outlets whereas the latter presents a discretized product that seamlessly covers rivers in the conterminous United States (CONUS). Both versions used neural networks to provide multiscale parameterization and process-based equations to provide structural backbone, trained them together (“end-to-end”) on 2,807 basins across CONUS, and evaluated them on 4,997 basins. Both versions show the great potential to elevate future NWMs for extensively calibrated as well as ungauged sites: the median daily Nash-Sutcliffe efficiency (NSE) of all 4,997 basins is improved to around 0.68 from 0.49 of NWM3.0. As they resolve heterogeneity, both greatly improved simulations in the western CONUS and also in the Prairie Pothole Region, a long-standing modeling challenge. The Muskingum-Cunge version further improved performance for basins >10000 km2. Overall, our results show how neural-network-based parameterizations can improve NWM performance for providing operational flood predictions while maintaining interpretability and multivariate outputs. We provide a CONUS-scale hydrologic dataset for further evaluation and use. The modeling system supports the Basic Model Interface (BMI), which allows seamless integration with the next-generation NWM.

Electromagnetic ion cyclotron (EMIC) waves are believed to cause the loss of relativistic electrons from the outer radiation belt into the atmosphere due to pitch angle scattering. However, it is still unclear whether all EMIC waves can scatter relativistic electrons or which conditions are favorable for pitch angle scattering by EMIC waves. In this study, we performed a two-year data analysis of EMIC waves and relativistic electron precipitation (REP) caused by EMIC waves, from 1 November 2016 to 31 October 2018. EMIC waves were observed using a ground-based magnetometer installed at Athabasca (ATH), Canada. REP events were identified from very low-frequency radio waves propagated from the transmitters at the NDK and NLK stations (North Dakota and Seattle, USA, respectively) to the receiver installed at ATH. The magnetic local time dependence of EMIC waves showed higher occurrence rates in the dawn sector. In contrast, EMIC waves accompanied by REP were localized in the dusk sector and were likely to occur during geomagnetic substorms. We found that EMIC waves accompanied by REP were associated with the main phase of geomagnetic storms and occurred inside the plasmapause. These results suggest that the EMIC waves that cause REP occur in the overlap region between the ring current and dense cold plasma during the main phase of geomagnetic storms. This is consistent with previous studies describing that the electron resonant energy with EMIC waves is lower in regions with high plasma density.

This study reports a peculiar nighttime ionospheric enhancement in the total electron content (TEC) from the geostationary (GEO) satellites in response to the geomagnetic superstorm of May 2024. The enhancements occurred at low to mid-latitudes during the storm’s recovery phase on 11-12 May, with the TEC values almost twice as high as the quiet ones. Surprisingly, the nighttime ionospheric enhancements sub-rotated westward with a speed of ~130.5 m/s. The nighttime TEC enhancements lasted ~5-7 hours for a given location; however, they persisted over half a day over wide longitude ranges. Meanwhile, ionosonde data from two equatorial ionization anomaly (EIA) stations showed a higher peak height of the F2 layer, and a significant double-crest EIA structure was observed by both GEO TECs and in situ electron densities from China Seismo-Electromagnetic Satellite during this period of interest, indicating a possible contribution from disturbance electric fields producing nighttime eastward equatorial electric fields. Nevertheless, it remains a mystery whether the nighttime TEC enhancement and its movement were associated with the wind disturbance dynamo.

Large volcanic eruptions strongly influence the internal variability of the climate system. Reliable estimates of the volcanic eruption response as simulated by climate models are needed to reconstruct past climate variability. Yet, the ability of models to represent the response to both single-eruption events and a combination of eruptions remain uncertain. We use the Community Earth System Model version 2 along with the Whole Atmosphere Community Climate Model version 6, known as CESM2(WACCM6), to study the global-mean surface temperature (GMST) response to idealised single volcano eruptions at the equator, ranging in size from Mt.\ Pinatubo-type events to supereruptions. Additionally, we simulate the GMST response due to double-eruption events with eruption separations of a few years. For large idealised volcanic eruptions, we demonstrate that double-eruption events separated by four years combine linearly in terms of GMST response. In addition, the temporal development is similar across all single volcanic eruptions injecting at least \(\SI{400}{\tera\gram(SO_{2})}\) into the atmosphere. Since only a few eruptions in the past millennium occurred within four years of a previous eruption, we assume that the historical record can be represented as a superposition of single-eruption events. Hence, we employ a deconvolution algorithm to estimate a historical GMST response pulse function for volcanic eruptions, based on climate simulation data from 850 to 1850 taken from a previous study. By applying the estimated GMST response pulse function, we can reconstruct most of the underlying historical GMST signal. Furthermore, the GMST response is significantly perturbed for at least seven years following eruptions.

Decision-makers urgently need fit-for-purpose, actionable climate information to address worsening risks to water security due to climate change. To help address this need, we pioneer new work that builds on a recently established standardized benchmarking framework to assess downscaled precipitation simulations and explore how benchmarking historical, fundamental model performance impacts confidence in regional precipitation projections. Inspired by frameworks used by the Coupled Model Intercomparison Project (CMIP) community to navigate the “ensemble of opportunity” that explore the spread, independence, and performance of CMIP models, we assess future confidence across three related categories: model agreement, dependence, and performance. Using data from the Coordinated Regional Downscaling Climate Experiments (CORDEX)-Australasia domain and Southern Australia as a case study, we highlight how benchmarking only “fundamental,” historical model performance improves confidence in regional precipitation projections across these categories of confidence. We find that including fundamentally flawed models in an ensemble can indicate a false level of confidence and model agreement in regional climate projections in annual and wet-season total rainfall and rainfall extremes. We find that our benchmarked subset reduces the spread in projections across season-rainfall index combinations without underestimating observed natural variability or end-of-century uncertainties due to the climate change response. By taking a novel approach to address the coupled interdependencies between global climate models and regional climate models in our dynamically downscaled ensemble, we find that we can increase confidence though historical benchmarking spatially and temporally without over-constraining plausible future projections.

A document by Doris Voina. Click on the document to view its contents.

In this study, we show that non-thermal collisions can play a significant role in shaping Europa's exospheric structure. Collisions between radiolytically produced O2 and the O produced via electron impact dissociation of O2 play a significant role in affecting the exospheric structure and escape rates. Specifically, O+O2 collisions lead to the production of a non-thermal O2 population, and increase the O2 escape while decreasing the O escape. These collisions are dependent on three specific physical parameters: (1) the density of O2 , (2) the electron impact dissociation rate of O2 , and (3) the O+O2 collision cross section. We demonstrate here that O+O2 collisions affect Europa's atmosphere even in the lowest limits considered. Thus, to more accurately determine the influence O+O2 collisions have on Europa's atmosphere in preparation for the forthcoming spacecraft missions, Europa Clipper and the JUpiter ICy moons Explorer (JUICE), these physical parameters need to be better constrained.

In this study, we show that non-thermal collisions can play a significant role in shaping Europa's exospheric structure. Collisions between radiolytically produced O2 and the O produced via electron impact dissociation of O2 play a significant role in affecting the exospheric structure and escape rates. Specifically, O+O2 collisions lead to the production of a non-thermal O2 population, and increase the O2 escape while decreasing the O escape. These collisions are dependent on three specific physical parameters: (1) the density of O2 , (2) the electron impact dissociation rate of O2 , and (3) the O+O2 collision cross section. We demonstrate here that O+O2 collisions affect Europa's atmosphere even in the lowest limits considered. Thus, to more accurately determine the influence O+O2 collisions have on Europa's atmosphere in preparation for the forthcoming spacecraft missions, Europa Clipper and the JUpiter ICy moons Explorer (JUICE), these physical parameters need to be better constrained.

Natural flood risk management in the tropics: Prospects in the biodiverse archipelagic nation of the Philippines