Climate change disproportionately impacts vulnerable communities around the globe. Previous work has shown that more socially vulnerable communities at the city and regional level within the contiguous United States (CONUS) are exposed to higher temperatures, but the impact of future warming on this unequal heat exposure remains unknown. We assess past and future average daily maximum temperature exposure across the CONUS in high- and low-vulnerability locations using a social vulnerability index (SVI). We find that the disparity in temperature exposure for high-SVI areas increased from ~1.3°C (1951-1980) to ~1.6°C (1994-2023). Using an ensemble of downscaled climate models, we assess future impacts at global warming levels of 1.5°C, 2°C, and 3°C. Specifically, we compare the number of days/year that exceed air temperature thresholds recommended for safe fan use (35°C, 39°C) in high-SVI and low-SVI areas. We find that for exposure to a 35°C air temperature threshold, at 1.5°C global warming there is an average annual exposure difference of ~16 days, at 2°C ~18 days, and at 3°C ~22 days. For exposure to a 39°C threshold, at 1.5°C global warming there is an exposure difference of ~5 days, at 2°C ~6 days, and at 3°C ~9 days. These results highlight that in many low-elevation, high-SVI areas future warming will disproportionately increase the number of days exceeding cooling and adaptation-relevant temperature thresholds. These findings further support the need to slow global warming to lessen adverse impacts for all communities, and they emphasize the need to direct adaptation efforts towards more vulnerable communities.

Seismic faults are known to exhibit a high level of spatial and temporal complexity, and the causes and consequences of this complexity have been the topic of numerous research works in the past decade. In this paper, we investigate the origins and the structure of this complexity by considering a numerical model of laboratory earthquake experiment, where we introduce a statistically homogeneous fault but allow it to evolve spontaneously to its natural level of complexity. This is achieved by coupling the elastic deformability of the off-fault medium (and therefore allowing for heterogeneous stress fields to develop) and the discrete degradation and gouge formation at the fault plane (and therefore allowing for structural heterogeneity to develop). Numerical results show the development of persistent stress, damage, and gouge thickness heterogeneities, with a much larger variability in space than in time. Strong positive correlations are found between these quantities, which suggest a positive feedback between local normal stress and damage rate, only mildly mitigated by the mobility of the granular gouge in the interface. For a wide range of confining stresses, after a sufficient number of seismic cycles, the fault reaches a state of established disorder with a constant quadratic roughness, a certain amount of periodicity at the millimetric scale, and a self-affine character for smaller spatial scales. Both the typical height-to-wavelength ratio of geometrical asperities and the Hurst exponent of along-slip stress profiles are in good agreement with previous field or lab estimates.

During the 21-22 January 2005 magnetic storm, the FAST satellite observed warm (< few keV) ions in discrete energy bands on the dayside at ~3000 km altitude for more than 6.5 hours. We suggest that the ionospheric energy-banded ions represent the low-altitude edge of the warm plasma cloak observed simultaneously by magnetospheric satellites. This is a clear example of the multi-species ion energy bands (10 eV to several keV) observed during strong magnetic storms by the FAST satellite, stretching from the diffuse auroral region to the plasmapause with lifetimes up to 12 hours. The close association of these energy-banded ions with magnetic storms, their broad latitudinal extent, and the presence of multiple ion species in the same energy band, rather than at the same velocity, indicate that this is a distinct phenomenon from other types of energy-banded ions. During the 21-22 January 2005 magnetic storm, the dayside ion energy band structures, centered at 10 eV (H+), 40 eV (H+ and He+), and 160 eV (H+, He+, and O+), were consistent with a “time-of-flight and velocity filter” formation process acting on a near-cusp, impulsive outflow of a < 200 eV multi-species ion-source population, poleward and in the same hemisphere as FAST. Understanding the sources and dynamics of warm energy-banded ions and their linkage to the warm plasma cloak is important because during superstorms these ions are transported deep into the plasmasphere to L values as low as L~1.2 in the dawn sector, significantly altering the energetics of the mid-latitude ionosphere

Biharmonic (or higher order) mixing of potential vorticity (PV) combines biharmonic mixing of momentum and isopycnal thickness. It is applied in a realistic eddy-permitting model of the North Atlantic Ocean by a simple modification of the standard scheme for harmonic isopycnal thickness mixing or bolus velocity. The effect of biharmonic PV mixing is compared to the one of biharmonic mixing of momentum only. Results are similar except for more realistic mixed layer depths using PV mixing. It is also shown how harmonic isopycnal thickness mixing with negative definite dissipation representing an energy source, in short negative bolus velocity, can be implemented in existing ocean models by another simple modification of the standard scheme. While negative bolus velocity injects available potential energy to the model, previous backscatter formulations using negative definite harmonic momentum mixing inject kinetic energy by sharpening velocity gradients. Both backscatter formulations, combined with the more scale selective dissipation by biharmonic PV mixing and a subgrid-energy budget to control the energetics, reproduce previously reported positive effects by backscatter, such as a more realistic north-west corner of the North Atlantic Current and Gulf Stream path, but negative bolus velocity works better in our configuration. Furthermore, eddy production rates by baroclinic instability are enhanced by negative bolus velocity, but reduced to zero by backscatter using negative definite harmonic momentum mixing.

JupyterHub is an open-source system enabling multiple users to access individual computational environments. This facilitates collaborative development and execution of Jupyter notebooks, Python scripts, and other tools among researchers and educators through a unified interface. Through the integration of container technologies, including Docker, JupyterHub achieves seamless scalability for numerous users while maintaining efficient computational resource management. This flexible approach is especially useful in specialized areas like planetary data science, which requires robust and reproducible workflows to manage large volumes of mission data. The Europlanet GMAP project employs a Docker-based JupyterHub deployment to centralize essential data processing tools, such as the Integrated Software for Imagers and Spectrometers (ISIS) and the NASA Ames Stereo Pipeline (ASP). These open-source tools facilitate tasks ranging from image calibration and map projection to stereogrammetry and 3D modeling. The deployment of these elements within Docker containers facilitates simplified installation and consistent performance across disparate hardware configurations. The use of preconfigured image formats within ISIS, ASP, and other GIS and Python libraries allows planetary scientists to efficiently process raw data into analytical products, including Digital Terrain Models (DTMs). Additionally, JupyterHub's architecture enables secure collaboration via authentication methods (e.g., OAuth, GitHub), with concurrent provision for private and shared data directories. This integrated framework promotes reproducible research by streamlining the sharing of scripts, notebooks, and workflows. The GMAP JupyterHub platform significantly accelerates scientific discovery through the reduction of technical barriers, the promotion of standardization, and the provision of global access to planetary data science resources.

Since the 2010 launch of Cryosat-2, a new generation of altimeters, referred to as SAR altimetry, has emerged and partially replaced the previous conventional altimeters known as LRM altimetry. A surface slope correction has been previously developed for LRM altimetry. However, the differences in the way the two altimeters work, and in particular their radar footprint, make LRM altimeter slope correction inapplicable to SAR altimetry. Thus, in this paper, a slope correction model is provided for SAR altimetry, derived from the LRM-based approach. The shape of the SAR footprint induces that height correction depends on each satellite mission. Consequently, a generic method allowing to generate global maps of height correction for distinct missions is provided. The maps are computed for the Sentinel-6A mission and the importance of correcting this effect for SAR altimetry is highlighted by studying the sea surface height anomaly biases between Jason-3 LRM altimetry and Sentinel-6A SAR altimetry during their tandem phase. Finally, it is shown that applying the slope correction to Sentinel-6A SAR mode sea surface height anomaly measurements enhances their correlation with the latest MSS model, reducing the root mean square error between the sea surface height anomaly and the MSS model by up to 1 cm.

Observations of solar energetic particles (SEPs) accelerated at collisionless shocks driven by coronal mass ejections (CMEs) highlight the importance of understanding proton transport in velocity space. In this study, we present an ensemble model based on the one-dimensional Fokker-Planck equation to estimate proton flux from CME-driven shocks propagating toward Earth. Using a CME analysis tool with coronagraph data, we derived initial conditions from key CME characteristics, including CME speed, angular width, Alfvén Mach number, and plasma beta. We then solved the one-dimensional Fokker-Planck equation under the test-particle regime, applicable to weak CME-driven shocks (M_A ~ 1 − 4) where the dynamical pressure of shock accelerated particles is low compared to thermal pressure. Notably, our model incorporates the effects of Alfvén wave transmission and reflection at shocks, which significantly influence the efficiency of diffusive shock acceleration (DSA) and the transport of shock-accelerated particles in low-beta CME-driven shocks. To address systematic uncertainties from initial conditions obtained through the CME analysis tool and the nonlinear dynamics of the shock surface, including turbulence, we employed an ensemble approach for critical variables impacting DSA efficiency, such as the Alfvén Mach number, plasma beta, and upstream wave amplitude. By estimating proton flux during SEP events in 2024, our ensemble model produced predictions is consistent with observations within a 1-sigma deviation, highlighting the importance of Alfvénic drift physics in SEP models of particle acceleration at shocks.

Syn- to late-orogenic extension caused by gravitational collapse is a process that has been documented in most orogens. In this paper, we investigate the contemporaneous stress field in Taiwan to examine syn-orogenic extensional faulting and the possible gravitational collapse modes by which it is taking place. We use a large, well-constrained, clustered earthquake focal mechanism data set from which we calculate the contemporaneous stress field (σ1, σ2, σ3), the direction of the maximum compressive horizontal stress (SH), and determine the most likely fault plane orientations and kinematics. Our results show that, in the upper 21 km of the crust, shearing, with lesser compression are the dominant stress regimes in the Western Foothills and Hsuehshan Range, resulting in a complex interaction of strike-slip (with transpression and transtension) and thrust faulting. Extension is predominately localised in the upper 14 km of the crust in the Central Range, where it is roughly orogen-parallel. SH and the best-fit fault planes in the Central Range strike roughly NW-SE, at a high angle to the structural and topographic grain. At depths greater than 21 km, compression and shear (with transpression and minor extension) are the dominant stress regimes throughout Taiwan. Along the eastern flank of the mountain belt, mixed compression and shear stress regimes at depths greater than 50 km are related to the Manila and Ryukyu subduction zones. Our results suggest that Taiwan is undergoing orogen-parallel extension as a result of lateral extrusion with free-boundary gravitational collapse.

A document by Joseph Nicholas. Click on the document to view its contents.

• A parametric study of electrostatic analyzers based on the donut topology with a 0-20keV energy range was conducted • A set of 3 construction parameters can be used to carefully tune the geometric factor and energy resolution at a specific angular resolution • It suggests to be a versatile concept for a variety of applications from space weather to performance intensive science missions.

Migrant labourers typically work long hours at physically demanding tasks without air conditioning, and they account for a considerable fraction of India’s population — a share that is increasing with urban growth. However, changes in heat stress and labour capacity in major urban centres that attract rural-to-urban work migrants remain unexplored. Moreover, it remains unclear how the increased heat stress and reduced labour capacity under the warming climate will alter the most preferred workplaces for migrant labourers in India. Here, we use station-based observations, reanalysis, and climate model projections to reconstruct trends and variability in heat stress metrics, including wet-bulb temperature (Tw for indoor exposure) and wet-bulb globe temperature (WBGT for outdoor exposure). We show that during 1980-2021, most rural-to-urban migration hotspots in north, east, and southern India witnessed a significant (p < 0.05) rise in Tw, indicating elevated indoor heat stress. Over that interval, outdoor heat stress has considerably increased and led to a ~10% decline in labour capacity in these hotspots. A substantial rise in the indoor and outdoor heat stress exposure of migrants and a reduction in their physical labour capacity is projected with each additional degree of global warming. El Nino-Southern Oscillation variability can also significantly enhance these effects. Effective mitigation and adaptation options are needed to reduce the risks migrant workers face due to increasing indoor and outdoor heat stress in India.

A set of MHD equations is developed for multiple ion species in the limit of small Larmor radius. The derivation proceeds to explicitly calculate the Lorentz force resulting from the small ion drift velocities. The net effect is that in this limit all the ions move perpendicular to the magnetic field with the same E×B speed, but are free-streaming relative to one another in the parallel direction. The ions couple one to another in the parallel direction from changes in the magnetic field direction, leading to a collision-like term that, however, maintains a constant total kinetic energy. The equations governing parallel (centrifugal) acceleration, which may be an important process for ionospheric outflow, are then derived. The dispersion relation for a two-species, isotropic fluid with arbitrary mass and charge fractions, as well as electron pressure, is derived and the resulting wave modes are analyzed. A planar Alfvén mode separates from other, generally compressible, modes. It becomes unstable when the ram pressure of the streaming exceeds the firehose limit. The remaining modes satisfy a sixth order equation in the phase speed when counterstreaming and electron pressure are allowed. Without counterstreaming, three stable modes always exist, with two counter-propagating waves each, regardless of the presence of electron pressure. For the streaming case there are three modes, with two asymmetrically propagating waves each, whose behavior can be quite complicated, especially near the firehose instability limit. An example global magnetosphere simulation of a geomagnetic storm is presented using the derived multifluid formalism.

Vertical mode and rotary-with-depth statistics are compiled from a global dataset of full-depth lowered ADCP baroclinic velocity profiles. Mode-1 standing waves make up half (~0.5) profiles at the equator, increasing to ~0.9 at 60-70ºS and in boundary currents and the Antarctic Circumpolar Current. However, this implies that higher modes dominate in almost half of the profiles. Rotary clockwise-and counterclockwise-with-depth profiles each make up ~0.2 of the profiles at mid and low latitudes, mostly in modes 2 and higher. The mode-1 zero-crossing or node is often offset relative to WKB-stretched mid-depth. Surface and bottom anomalies are present in ~0.9 of the profiles, particularly those with higher energy, with bottom anomalies slightly more common over rougher topography. Low modes are responsible for redistributng and homogenizing the internal-wave field from localized sources but the practice of fitting coarsely-resolved profile data to mode-1 standing-wave structure is not valid everywhere, particularly near the equator.

Magnetic holes have been studied for decades, but their three-dimensional structure has not been thoroughly investigated until now. We have identified solar wind magnetic holes observed simultaneously by the four Cluster spacecraft. By transforming the observations into a local coordinate system and identifying a principal axis, we fit the results to a three-dimensional Gaussian model to estimate their scales. We present four events that highlight the various aspects of this method, emphasizing the critical role of coordinate system selection in the analysis. The principal axis of the holes varied, and in three out of four cases, were not aligned with the magnetic field, instead forming angles between 50 and 80 degrees, suggesting that magnetic holes are not necessarily oriented along the magnetic field. Finally, our analysis reveals that the scale of the holes along one direction is significantly longer than along the other two, suggesting an elongated ellipsoid as a typical shape for their morphology.

We present Mars Express (MEX) observations of heavy pickup ions (HPUI) at Mars and a new method to derive IMF properties. The MEX HPUI measurements were organized using the upstream interplanetary magnetic field (IMF) directions measured by the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. Since these HPUIs are mostly accelerated by the electric field in the upstream and magnetosheath regions, the IMF component perpendicular to the solar wind, both directions and magnitudes, can be derived from the HPUI flux directions, energies, and positions measured by MEX. The derived IMF properties were compared with the simultaneous IMF measurements by MAVEN, which showed good agreements with each other with the accuracy comparable to most previous IMF proxies based on MAVEN data. This new IMF proxy does not require any magnetic field data and hence can be applied to the long time period prior to the MAVEN mission.

Normal fault slip is regularly quantified for instantaneous seismic events and across geological timescales in rate-and-state friction frameworks. However, recent studies have shown that normal faults may undergo transient aseismic slip exceeding time-averaged rates, outside of steady state conditions. This highlights the need for further detailed observation of both coseismic and aseismic deformation on normal faults to better constrain how structures accommodate and release strain across all seismic stages. Here, we exploit open-source, InSAR-derived vertical ground motion data from the European Ground Motion Service (EGMS) to evaluate sub-mm scale deformation across active faults in the Larissa Basin, where two Mw > 6 earthquakes occurred in 2021, and the North Gulf of Evia, Central Greece. We resolve the spatial and temporal evolution of uplift and subsidence fields of the Larissa earthquake sequence, finding elevated coseismic uplift to subsidence ratios of 1:6-9. EGMS time series across the Costal Fault System of the North Gulf of Evia imply normal fault slip at above-creep throw rates of 2-3 mm/yr with limited associated seismicity. The nearby seismogenic Atalanti Fault shows no differential ground motion across its plane and is in an apparent locked state. Observed variable slip behaviours imply that long-term, geologically derived throw rates may combine transient periods of elevated aseismic slip, coseismic slip, and steady state motion. We consider these findings in the context of seismic hazard while assessing the applicability of EGMS data in tectonic studies to bridge an important gap in resolving fault motion across all spatial and temporal scales.

Soil moisture (SM) representation varies among Earth System Models (ESMs) like those in the 6th Coupled Model Intercomparison Project (CMIP6). While surface SM (averaged over the top 10 cm) is similarly defined across models, the layered SM differs due to varying definitions of the soil profile in models. This inconsistency complicates ESM-based analyses involving vertical SM profiles. Here, we compare the vertically integrated layered SM (mrsol) with surface SM (mrsos) across different CMIP6 models. Our findings reveal that for some models, the integrated mrsol matches mrsos globally; for others, it matches only in certain grid cells; and for a few, it never matches. We showcase these discrepancies and discuss several potential causes, including inconsistent variable mapping, interpolation errors, and model-specific issues such as frozen soil handling and incorrect depth definitions. These discrepancies impact ESM-based SM studies, highlighting the need for careful consideration when using mrsol or mrsos from model simulations.

Active eddies in the eastern Weddell Gyre (WG) facilitate water mass exchange between the WG and warmer Antarctic Circumpolar Current, driving warm inflow into the WG. Using observations and data-assimilating model output, the impact of seasonal extension of the eastern WG on the local eddy kinetic energy (EKE) field was investigated. By altering the ambient density field, the seasonal extension modulates both EKE production via baroclinic instability (BCC) and EKE redistribution through the pressure work (PW). When WG contracts in spring-summer, the EKE produced by BCC tends to accumulate at eastern WG due to the weak outward redistribution by PW. Whereas, during autumn-winter when WG extends, enhanced PW causes a greater EKE outflow than local production. Understanding these dynamics is essential for predicting future eddy-induced warm inflow into the WG and subsequent bottom water formation, especially under the scenario of a potentially extending WG due to climate change.