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Journal articleZelinka MD, Myers TA, Qin Y, et al., 2026,
Recent cloud trends and extremes reaffirm established bounds on cloud feedback and aerosol-cloud interactions
, Communications Earth & Environment, Vol: 7, ISSN: 2662-4435Earth’s energy imbalance has increased markedly over the past two decades, reaching a record in 2023. Both the long-term trend and year-to-year variations are linked to reduced reflection of sunlight by low-level clouds, which is pronounced over Northern Hemisphere oceans. However, the causes of these cloud changes and their implications for future Earth system evolution are unknown, raising concerns about a stronger-than-expected cloud feedback. Here we quantify the meteorological factors behind interannual cloud-radiative anomalies, several of which aligned to produce the extreme 2023 value. These meteorological variations are superposed on a background of declining sulfate aerosol concentrations, contributing to a sustained decrease in cloud reflection over the past 22 years. The resulting constraints on cloud feedback and aerosol forcing are consistent with previous studies, supporting an equilibrium climate sensitivity near 3∘C (likely range 2.7–4.1∘C). Thus, recent observations do not indicate an emerging stronger cloud feedback or underestimated future warming.
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Journal articleDakeyo JB, Ervin T, Bale S, et al., 2026,
On the Radial Evolution of the Solar Wind: The Source Alignment Method Applied to Parker Solar Probe and Solar Orbiter Observations
, Astrophysical Journal, Vol: 1006, ISSN: 0004-637XThe properties of the solar wind, as measured in situ throughout the heliosphere, depend both on the characteristics of its coronal source and on the intrinsic processes governing its interplanetary evolution. Recently, radial and Parker spiral alignment techniques have been applied to Parker Solar Probe (PSP) and Solar Orbiter (SO) observations to investigate the radial evolution of the same solar wind parcel. These studies have shown that the solar wind can undergo significant acceleration even beyond its primary acceleration region (i.e., above 15 R<inf>⊙</inf>). However, such radial and Parker spiral alignments are rare in practice, which limits the statistical significance and general applicability of the results. We introduce a new source alignment technique designed to overcome these limitations. Using magnetic backmapping, we associate similar solar wind streams observed by the two spacecraft based on the proximity of their photospheric footpoints, combined with additional in situ stream similarity criteria. Applying the source alignment method to PSP and SO observations, we identify a total of 548 alignment intervals, each lasting 30 minutes. By constructing statistics over all alignments, we find that the solar wind speed increases by an average of 45% per radial decade (approximately 147 km s<sup>−1</sup>) between the two probes. This result demonstrates that solar wind acceleration in the inner heliosphere remains significant compared to that occurring below 15 R<inf>⊙</inf>. Among the different studied plasma parameters, the radial evolution of the electron temperature and plasma density shows the strongest anticorrelation with the increase in bulk velocity.
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Journal articleManolis AA, Manolis TA, Vouliotis A, et al., 2026,
Pericarditis/Myopericarditis/Pericardial Effusion: A Contemporary Approach to Diagnosis and Management.
, Curr Vasc PharmacolPericarditis is a common disease caused by various factors such as viral infections, systemic diseases, or drugs. A diagnosis of pericarditis is rendered in up to 5% of Emergency Room (ER) visits for non-ischemic chest pain. It is diagnosed when pleuritic chest pain is present, accentuated in the supine position, accompanied by ECG changes comprising new extensive ST-segment elevation and PR depression, a pericardial friction rub, and new or increased pericardial effusion on echocardiography. In North America and Western Europe, the most common causes of acute pericarditis are idiopathic or viral, followed by post-procedural (iatrogenic) pericarditis, radiation therapy, and cardiac surgery. Tuberculosis is the most common cause of pericarditis in endemic areas and is managed with antituberculosis therapy, with corticosteroids used when there is concurrent constrictive pericarditis. New diagnostic techniques have aided the sampling and analysis of pericardial fluid and in determining its cause. Treatment of pericarditis comprises high-dose Non-Steroidal AntiInflammatory Drugs (NSAIDs) for uncomplicated cases, with doses tapered when symptoms have subsided and C-reactive protein level has normalized, typically over several weeks. Colchicine (often a 3-6-month course) is needed to both alleviate symptoms and decrease recurrences, while glucocorticoids and newer therapies with interleukin-1 blockers are reserved for recurrences and/or failures of prior therapies. Integrated use of new imaging methods facilitates more precise detection and better management of complications such as pericardial effusion or constriction. The diagnostic yield of extensive laboratory evaluation and pericardiocentesis remains low; hence, invasive procedures should be limited mostly to patients in whom a therapeutic intervention is needed. The majority of pericardial effusions can be safely drained with an echo-guided percutaneous technique. Pericardiectomy remains the definitive treatment for
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Journal articleFredericks L, Rugenstein M, Thompson DWJ, et al., 2026,
Quantifying the radiative response to surface temperature variability: a critical comparison of current methods
, Journal of Climate, Vol: 39, Pages: 4101-4116, ISSN: 0894-8755Over the past decade, it has become clear that the radiative response to surface temperature change depends on the spatially varying structure in the temperature field, a phenomenon known as the “pattern effect.” The pattern effect is commonly estimated from dedicated climate model simulations forced with local surface temperature patches (Green’s function experiments). Green’s function experiments capture causal influences from temperature perturbations but are computationally expensive to run. Recently, however, several methods have been proposed that estimate the pattern effect through statistical means. These methods can accurately predict the radiative response to temperature variations in climate model simulations. The goal of this paper is to compare methods used to quantify the pattern effect. We apply each method to the same prediction task and discuss its advantages and disadvantages. Most methods indicate large negative feedbacks over the western Pacific. Over other regions, the methods frequently disagree on feedback sign and spatial homogeneity. While all methods yield similar predictions of the global radiative response to surface temperature variations driven by internal variability, they produce very different predictions from the patterns of surface temperature change in simulations forced with increasing carbon dioxide (CO2) concentrations. We discuss reasons for the discrepancies between methods and recommend paths toward using them in the future to enhance physical understanding of the pattern effect.
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Journal articlePugsley G, Gryspeerdt E, Nair V, 2026,
Reply to Yu et al.: Meteorological covariations do not reproduce diurnal cloud fraction response to aerosol.
, Proc Natl Acad Sci U S A, Vol: 123 -
Journal articleBurne S, Boscoboinik G, Bertucci C, et al., 2026,
Correlated response of the Martian dayside magnetic pileup boundary and bow shock to solar wind and planetary drivers
, The Astrophysical Journal, Vol: 1005, ISSN: 0004-637XThe interaction between the supermagnetosonic solar wind and the atmosphere of the weakly magnetized planet Mars forms an induced magnetosphere preceded by a magnetic pileup boundary (MPB) and bow shock (BS). In situ measurements have shown that these boundaries are permanent and well-defined structures that exhibit significant variability driven by external (Sun, solar wind) and internal (planetary) factors. In this work, we used MAVEN observations from 2014 to 2019 to analyze the coupled behavior of the BS and MPB, focusing on their spatial correlation and variability under varying conditions. We examine contiguous BS-MPB spacecraft crossings and the magnetosheath region between them, and we explore the effects of various plasma parameters on the relative position of the boundaries and the thickness of the magnetosheath. We demonstrate a statistical correlation between the BS and MPB positions across multiple timescales, including sustained local solar wind and planetary conditions, seasonal changes, and solar cycle variations. These results support the interpretation that the MPB plays a key role as an electromagnetic obstacle to the solar wind, effectively controlling the formation of the bow shock. We also confirm the limited size of the Martian magnetosheath, both in absolute terms and relative to fundamental plasma scales, which has important implications for understanding the microscopic plasma processes responsible for solar wind thermalization. While acknowledging the limitations of single-spacecraft measurements, this study provides a foundation for future multipoint probing of the Martian environment and the magnetosphere as a system.
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Journal articleAuestad H, Shibu A, Ceppi P, et al., 2026,
The latent heating feedback effect on storm tracks in current and future climates
, npj Climate and Atmospheric Science, Vol: 9, ISSN: 2397-3722Extratropical storms release latent heat as they transport warm, moist air poleward and upward. That latent heating feeds back on storms by intensifying individual cyclones and by altering the environmental conditions for the growth of storms, constituting a latent heating-dynamics feedback. As the climate warms, storm-track latent heating increases, but the role of this feedback in a future climate remains unclear. Using atmospheric general-circulation model experiments that separate the coupled heating-dynamics feedback from climatological changes in latent heating, we show that this feedback plays a leading-order role in intensifying storm tracks under +4 K warming. The feedback increases lower-tropospheric storm intensity, compensating for reduced baroclinicity, while its upper-tropospheric effect is seasonal: amplifying summer eddies but damping winter ones. The feedback is critical for storms that grow in moist environments, typical for summer and warmer climates, underscoring the need for accurate representation of moist processes in climate models.
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Journal articleHartinger MD, Shi X, Verkhoglyadova O, et al., 2026,
Statistical analysis of Pc3‐5 total electron content disturbances at mid‐Latitudes: comparison to the auroral zone
, Journal of Geophysical Research: Space Physics, Vol: 131, ISSN: 2169-9380<jats:title>Abstract</jats:title> <jats:p> Ionospheric Total Electron Content disturbances (dTEC) in the Ultra Low Frequency (ULF, timescales 10 min) range can be driven from below by processes at Earth's surface and lower atmosphere and from above by magnetospheric processes. Using magnetospheric satellite magnetometer, ground‐based magnetometer, and dTEC measurements in the auroral zone, Hartinger et al. (2025), <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://doi.org/10.1029/2024ja033456">https://doi.org/10.1029/2024ja033456</jats:ext-link> showed that over much of the Pc3‐5 band (∼2–50 mHz) ULF waves routinely drive dTEC perturbations correlated with magnetic field disturbances (dBground), suggesting dTEC could be used as a ULF wave diagnostic. Motivated by the significant differences expected for magnetosphere, ionosphere, atmosphere, and ground properties at a different latitude, we extend Hartinger et al. (2025), <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://doi.org/10.1029/2024ja033456">https://doi.org/10.1029/2024ja033456</jats:ext-link> to examine mid‐latitude ( degrees magnetic latitude) dTEC during conjunctions with the Van Allen Probes satellites, a ground magnetometer, and a Global Navigation Satellite System receiver. Consistent with the auroral zone, we find that dTEC often has a corresponding dBground signature, and that dTEC and dBground are well correlated with results dependent on the component of the magnetic field. We also find that dTEC amplitudes are lower (0.5 TECU) and tend to occur at higher frequencies than in the auroral zone, as expected for magnetospheric Pc3‐5 wave latitude dependence. In contrast to the auroral zone, we find that dTEC power does not have
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Journal articleTeixeira JCM, Burton C, Kelley DI, et al., 2026,
Assessing the impact of the Human Development Index on historical trends in the INFERNO fire model
, Earth System Dynamics, Vol: 17, Pages: 739-767, ISSN: 2190-4979Fire schemes within Earth System Models capture long-term historical trends in burnt area, but they struggle to reproduce the pronounced decline observed over the past two decades. This study investigates whether the observed decline in global burnt area during 1998–2016 can be better represented in the JULES-INFERNO fire model by introducing a globally uniform dependence on the Human Development Index (HDI) as a proxy for socio-economic fire controls. This approach substantially reduces regional biases in annual burned area. In Temperate North America, model bias decreases from +735.57 % to +44.46 %, with similarly large reductions in Central America, Southern Hemisphere South America, Europe, and the Middle East. HDI also improves the representation of burned area trends in eight of the 14 GFED4s regions with significant negative trends in observations. However, correcting large positive regional biases removes compensating errors in the original model, leading to a stronger global negative bias, which shifts from −34.35 Mha in JULES-INFERNO to approximately −111 Mha in JULES-INFERNO with the HDI implementation. Overall, while HDI improves regional performance and better captures observed downward trends in some regions, it also reduces interannual variability and underestimates larger fires. This highlights both the potential and limitations of representing socio-economic influences within fire models using a simplified globally uniform formulation.
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Journal articleDasgupta B, Pandey S, Houweling S, et al., 2026,
Global methane emission estimates from a dual-isotope inversion: new constraints from <i>δ</i> D-CH <sub>4</sub>
, Atmospheric Chemistry and Physics, Vol: 26, Pages: 8601-8616<jats:p> Methane (CH <jats:sub>4</jats:sub> ) is a potent greenhouse gas; however, the causes of its growth since 2006 are a subject of debate. While measurements of CH <jats:sub>4</jats:sub> mole fraction and carbon isotopic composition ( <jats:italic>δ</jats:italic> <jats:sup>13</jats:sup> C-CH <jats:sub>4</jats:sub> ) have been extensively used to investigate the global CH <jats:sub>4</jats:sub> budget, the hydrogen isotopic composition ( <jats:italic>δ</jats:italic> D-CH <jats:sub>4</jats:sub> ) remains underutilised despite its unique sensitivity to source types and oxidation processes. Here, we assimilate a newly harmonised 35-year dataset of dual isotope measurements from high-latitude monitoring stations in both hemispheres within a two-box Bayesian inversion to quantify global CH <jats:sub>4</jats:sub> sources and sinks. The model integrates prior emissions from five source categories based on global bottom-up inventories. Methane removal processes are represented by sink-specific kinetic isotope effects as tropospheric and stratospheric loss, and soil uptake. We find that the inclusion of <jats:italic>δ</jats:italic> D-CH <jats:sub>4</jats:sub> improves the model's ability to constrain emission apportionment between biogenic and thermogenic sources, particularly for fossil fuel emissions during the late 1990s and early 2000s, which affects CH <jats:sub>4</jats:sub&g
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Journal articleManolis AS, Manolis AA, Manolis TA, et al., 2026,
Occupational and Environment-Related Cardiovascular Disease: A Comprehensive Review of the Literature.
, Curr Vasc PharmacolWork is a social determinant of Cardiovascular (CV) and general health and can both influence and be influenced by health. The type of work, working conditions, and work environment are fundamental social determinants of CV and general health status. Climate change presents an urgent and increasing threat to workers' health, via both direct exposure to environmental risks and the indirect worsening of social and health inequalities. Occupational health, which focuses on the promotion of mental and physical health and well-being of workers, and the avoidance of occupationrelated health risks, is a crucial but less discussed concern and component of human health. Relevant research at the intersection of climate change and occupational health remains scarce. Additionally, mitigation of climate change and adaptation efforts are driving forces for rapid transformations in the workplace, including shifts towards sustainability and circular economy models. These transitions are creating new occupational hazards, including those concerning renewable energy and the circular economy sectors. Investment in occupational health research and surveillance should be increased to address the evolving influences of both climate change and the green transition, to enhance and protect workers' CV and general health. Among the work-related factors that play an important role in patients with CVD, the following seem crucial: work participation, physical and mental work capability, appropriate work, support from and flexibility of the work environment, inter-personal communication, person-centered milieu, and interdisciplinary communication. A moderate leisure-time physical activity combined with moderate occupational physical activity may be a more plausible way to combine these two activities to sustain and/or improve CV health. Such an approach may be able to ameliorate workrelated outcomes in patients with CVD. Finally, lifestyle interventions targeting multiple behaviors are also mos
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Journal articleDong Y, Lu K, Hwang Y-T, et al., 2026,
Tropical impacts of the Southern Ocean underestimated by mean-state biases
, Science Advances, Vol: 12, ISSN: 2375-2548Observed sea-surface temperature (SST) trends over recent decades feature cooling in the tropical eastern Pacific and the Southern Ocean (SO). Growing evidence suggests that tropical cooling may partly stem from remote impacts of the SO. Using a hierarchy of multimodel simulations, we demonstrate that these teleconnections are robustly modulated by the mean-state intertropical convergence zone (ITCZ): Models with a more realistic ITCZ simulate a stronger tropical SST response to SO forcing via stronger wind-evaporation-SST feedback. When realistic Antarctic meltwater forcing is included, correcting a model’s tropical mean-state bias yields a stronger tropical cooling response to meltwater-driven SO cooling, improving the agreement between simulated and observed SST trends. Our results suggest that the SO’s contribution to tropical warming patterns is systematically underestimated due to model mean-state biases. Improving representations of the mean-state climate is therefore critical for accurately assessing large-scale climate responses associated with historical and future warming patterns.
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Journal articleWyper PF, Squire J, Pariat E, et al., 2026,
Magnetic switchback formation: a review of proposed mechanisms
, Space Science Reviews, Vol: 222, ISSN: 0038-6308Magnetic switchbacks are large amplitude deflections of the magnetic field within the solar wind. They are Alfvénic in character and so are associated with a spike in velocity and a generally small variation in local plasma density. Early orbits of Parker Solar Probe revealed that the solar wind near the Sun is dominated by these structures, and therefore, they may be playing an important role in the energy budget and acceleration of the young solar wind. In this review, we present an overview of different mechanisms that have been proposed for how switchbacks could be formed. We group the mechanisms by whether they predominantly act in the low solar atmosphere or within the solar wind (in situ). We focus on mechanisms that can create reversals of the ambient magnetic field direction and, thus, account for the most extreme perturbations. The general consensus is that mechanisms in the lower solar atmosphere do not form such reversals on their own but provide the seed perturbations, flows, or particle beams necessary for in situ mechanisms to create switchbacks within the solar wind. Switchback observations thus likely contain an imprint of the coronal source of the seed perturbation or flow, which is evolved further locally by one of several plausible in situ mechanisms. We discuss the strengths and weaknesses of each mechanism and outline future observational and theoretical tests that could help differentiate between them.
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Journal articleSun W, Phan T, Huang J, et al., 2026,
Parker Solar Probe Observations of Compound Reconnection Exhaust Boundaries and Mirror-mode Structures in the near-Sun Heliospheric Current Sheet
, Astrophysical Journal Letters, Vol: 1003, ISSN: 2041-8205Magnetic reconnection is a fundamental physical process that can drive rapid conversion of magnetic energy into plasma bulk flows, thermal heating, and particle acceleration in space and astrophysical plasmas. Classical reconnection theory predicts that the Alfvénic reconnection exhausts are bounded by pairs of slow-mode shocks. However, identifying and characterizing these shocks through in situ spacecraft observations remains a challenge. Here, we report Parker Solar Probe observations of a reconnection exhaust embedded in the heliospheric current sheet at a heliocentric distance of 12.2 (Formula presented) R⨀. The reconnection exhaust is bounded on both boundaries by compound magnetic structures rather than a pair of pure slow shocks. Each boundary consists of a rapidly evolving, steep, inner slow shock, whose Mach numbers and shock-normal angles change significantly within several minutes, and an outer, gradual compound structure that comprises a slow shock and a rotational discontinuity. These slow shocks are quasi-perpendicular and are accompanied by enhanced proton perpendicular heating. Deep within the reconnection exhaust, high perpendicular temperature together with large plasma (Formula presented) β trigger mirror instability and generate mirror-mode structures. These observations provide new insights into the structure of reconnection exhaust boundaries and their role in energy conversion in the near-Sun plasma.
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Journal articleAlconcel L, Brown P, Oddy T, et al., 2026,
Long‐term trends in the calibration of the cluster fluxgate magnetometer instruments
, Journal of Geophysical Research: Space Physics, Vol: 131, ISSN: 2169-9380The calibration parameters of the Cluster mission's fluxgate magnetometer instruments have beendetermined and updated on a per‐orbit basis throughout the 24 years of the mission. Since there is no absolute field reference for vector measurements in‐flight, various spacecraft‐to‐spacecraft and instrument‐to‐instrument comparisons have been used to assess the accuracy of the measurements. Relative accuracy—consistency of the FGM measurements between spacecraft—is typically1%forfields up to 4,000nT,whichcoversmostof the key scientific regions visited by the Cluster spacecraft. Absolute accuracy is harder to quantify but may be as good as 2% over the same range. An analysis of long‐term trends in the calibration parameters shows variations on annual and mission‐length timescales, particularly for sensor offsets, while sensor gains and angles are remarkably stable. Offset variations are correlated with sensor temperature—for the Cluster 1 instrument in particular—and to a lesser extent with electronics temperature; coefficients are of the order 0.1 and 0.01 nT/ºC respectively. After correction for temperature effects, there is no clearly measurable offset drift over the mission lifetime. Statistics for all four spacecraft are presented. These data could be used to inform the design andimplementation of future missions employing fluxgate magnetometers. The spacecraft are found to bemagnetically “clean,” which allows in‐flight calibration techniques to be applied with confidence and precision,leading to consistently high‐quality magnetic‐field data sets available through the Cluster Science Archive.
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Journal articleCanu P, Bouzid V, Piberne R, et al., 2026,
STAFF instrument calibration, sensitivity, and performance evolutions during the cluster mission
, Journal of Geophysical Research: Space Physics, Vol: 131, ISSN: 2169-9380The Spatio-Temporal Analysis of Field Fluctuations(STAFF) instruments onboard the Cluster satellites were designed to measure magnetic fluctuations in the 0.2–12 Hz and 0.2–180 Hz frequency ranges from the Search-Coil Magnetometer (SCM), as well as electromagnetic spectra from the Spectrum Analyzer (SA) in the 8–4000 Hz range. They provided a considerable amount of data throughout the 24-year mission. The production and calibration of these datasets were detailed in Robert et al. (2014), which demonstrated its excellent quality and good agreement with the FluxGate Magnetometer (FGM) measurements over their commonfrequency range. The Cluster's 24 years of operation, which far exceed the nominal two-year mission, represent the longest flight of search coil magnetometers and offer a unique opportunity to evaluate their performance over such a long period, as well as to compare the results of four initially identical instruments. The present work, based on data now archived at the Cluster Scientific Archive (CSA), examines the evolution of these products after the first 11 years in space, and until the end of the Cluster operations in September 2024. The quality of the measurements, calibration, sensitivities, and their agreement between spacecraft proved to be excellent and remained stable throughout the mission. Comparison of spectra derived from the calibrated waveforms of STAFF (CWF) and FGM shows a very good agreement until the end of operations, a further proof of the high quality of their respective calibrations.
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Journal articleMitchell DG, Lario D, Raouafi NE, et al., 2026,
The 3He-rich SEP on Event 2024 April 1 at 27 Solar Radii—Indications of Acceleration by Waves and Implications of Coronal Source Location
, Astrophysical Journal, Vol: 1003, ISSN: 0004-637XParker Solar Probe (PSP) observations of a small dispersive event on 2024 April 1 reveal highly enriched <sup>3</sup>He abundance in the suprathermal energy range (40–250 keV nucleon<sup>−1</sup>). Time dispersion observed in this impulsive solar energetic particle (SEP) event is consistent with an estimated onset time of 22:50 UT on 2024 March 31. The event occurred during an orbital segment as PSP moved from about 27 R<inf>s</inf> to about 29 R<inf>s</inf> while outbound in orbit 19. For this segment of the orbit, PSP’s motion in Carrington coordinates remains within about 1° of the same Carrington longitude. The <sup>3</sup>He content is much larger than the usual SEP abundances, especially in this energy range. Additionally, the <sup>3</sup>He energy spectrum is not power law in shape, unlike the H and <sup>4</sup>He spectra. Heavy ions (O, Fe) are also somewhat enhanced. These compositional signatures suggest that this is an example of resonant wave–particle acceleration, as hypothesized for generating the suprathermal seed particles required to account for the enrichment of various species above solar abundances in shock (or compression) acceleration models of SEP events. Like many previously reported impulsive <sup>3</sup>He-rich events, this event is associated with an energetic electron beam, type III radio emission, and a hard X-ray flare. However, associating the hard X-ray event with this SEP event requires significant (∼60°) prompt longitudinal propagation of energetic particles in the low corona before they access open magnetic flux, complicating its interpretation as part of the source process for this particular event.
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Journal articleSvenningsson I, Yordanova E, Khotyaintsev YV, et al., 2026,
Electron heat flux and whistler instability in the Earth's magnetosheath.
, Phys Rev E, Vol: 113Despite heat flux's role in regulating energy conversion in collisionless plasmas, its properties and evolution in the magnetosheath downstream of the Earth's bow shock are scarcely explored. We use Magnetospheric Multiscale in situ measurements to quantify and characterize the electron heat flux in the magnetosheath. We find that the heat flux is shaped by the magnetosheath magnetic field as it drapes around the magnetosphere. While it is affected by solar wind upstream conditions and increases with magnetic field strength, it is not substantially changed by local magnetosheath processes. Also, the heat flux is limited by whistler instability thresholds.
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Journal articleKelly H, Archer M, Eastwood J, et al., 2026,
Superposition of doppler-shifting magnetopause Kelvin-Helmholtz modes through dynamic mode decomposition of a global MHD simulation
, Geophysical Research Letters, Vol: 53, ISSN: 0094-8276The Kelvin-Helmholtz instability (KHI) mediates the viscous-like solar-terrestrial interaction by generating magnetopause surface waves that quickly become non-linear. Basic theory predicts the locally most-unstable linear wave dominates. However, Kelvin-Helmholtz is a broad, convective instability that also amplifies waves originating upstream. We address this conundrum by applying dynamic mode decomposition to a Gorgon global magnetohydrodynamic simulation of the KHI. While distinct modes quickly grow at points along the magnetopause, signaling local generation, their energy continues to slowly grow downtail. Thus, a superposition is present along the magnetopause, where the dominant mode is not always the locally fastest-growing. Each mode's wavelength elongates downtail, correlating with the boundary layer flow speed due to the accelerating advective flow around the magnetosphere Doppler shifting the fixed-frequency waves. This may explain why longer wavelengths are observed in the tail than theory predicts and motivates further exploration of tangential inhomogeneities in basic Kelvin-Helmholtz theory.
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Journal articleWilson LB, Bale SD, Stevens ML, et al., 2026,
Electron Velocity Moments in the Solar Wind. II. Statistical Properties
, Astrophysical Journal, Vol: 1002, ISSN: 0004-637XBetween 2005 January 1 and 2017 November 25, the Wind spacecraft measured 3,996,051 electron velocity distribution functions (VDFs) in the near-Earth solar wind. The instrument was calibrated, and velocity moments were calculated up to the third moment (i.e., electron heat flux). The magnetic field and ion velocity moments have been interpolated to the midpoint time of the VDFs, where we have 3,947,607 finite electron velocity moments (most prior studies used <300,000 moments). The median values for the velocity moments are as follows: n<inf>e,int</inf> ∼ 5.43 cm<sup>−3</sup>, ∣V<inf>oe</inf>∣ ∼ 421 km s<sup>−1</sup>, T<inf>e,tot</inf> ∼ 12.7 eV, and ∣q<inf>e,∥</inf>∣ ∼4.92 μW m<sup>−2</sup>. The median values for the electron-to-proton temperature ratio is (Formula presented) Te,tot/Tp,tot ∼2.55, the electron temperature anisotropy A<inf>e</inf> = (Formula presented) Te,⊥/Te,∥ ∼ 0.89, total electron beta β<inf>e,tot</inf> ∼ 1.27, electron–electron collision frequency ν<inf>ee</inf> ∼ 0.18 day<sup>−1</sup>, and electron–electron Knudsen number K<inf>n,ee</inf> ∼ 2.57. The results are mostly consistent with previous studies except that K<inf>n,ee</inf> is significantly larger than some other works, which implies that the near-Earth solar wind is less collisional than may have been inferred.
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Journal articleLewis H, Eastwood J, Phan T, et al., 2026,
Parker solar probe observations of a flux rope embedded in a near-sun heliospheric current sheet magnetic reconnection exhaust
, The Astrophysical Journal (ApJ), Vol: 1002, Pages: 1-12, ISSN: 0004-637XIn situ observations by Parker Solar Probe (PSP) suggest that the heliospheric current sheet (HCS) undergoes near-continuous magnetic reconnection close to the Sun, in stark contrast to scarce observations of this phenomenon in the HCS at 1 AU. Situated at the boundary between sectors of opposite interplanetary magnetic field (IMF) polarity, reconnection in the HCS has important consequences for magnetic topology and plasma dynamics in the slow solar wind. We report observations of a reconnection outflow in theHCS near the Alfv´en transition region in PSP’s 17th solar encounter, featuring plasma jetting, proton temperature enhancement, and electron heat flux dropout. Embedded within the exhaust is a non-force-free flux rope plasmoid exhibiting counterstreaming strahl electrons, indicating connection at both ends to the Sun in an otherwise disconnected region of magnetic field. The flux rope features diminished isotropic protontemperature and lower bulk speed compared to the remainder of the HCS exhaust. Its oblique orientation and different plasma properties imply the flux rope originates from a different reconnection site to the HCS exhaust, suggesting PSP has intercepteda flux-rope-like streamer blob produced at the helmet streamer. Remote observations show several comparable blobs travelling in a distant coronal ray, demonstrating the possibility that the in situ flux rope is a streamer blob. The combination of in situ andremote observations demonstrate the role of magnetic reconnection in HCS dynamics, contributing to a growing understanding of this fundamental mechanism and its impact on the young solar wind.
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Journal articleHorbury T, OBrien HL, Greenaway C, et al., 2026,
The IMAP magnetometer
, Space Science Reviews, Vol: 222, ISSN: 0038-6308The magnetometer (MAG) is one of the ten scientific instruments on the Interstellar Mapping and Acceleration Probe (IMAP), which will take in situ and remote measurements from a Sun- Earth L1 halo orbit. MAG contributes to IMAP science goals of investigating the acceleration and propagation of energetic particles, as well as providing real-time space weather monitoringdata. The magnetometer is a conventional dual sensor fluxgate instrument with a noise floor under 10 pT at 1 Hz, taking science measurements continuously at 2 vectors/s as well as a burst mode of 64 vectors/s for at least 8 hours per day. It also provides a real-time space weathermonitoring product at 4 second cadence. We describe the requirements, design and performance of the instrument, including a novel lossless compression algorithm. Data products, processing and calibration plans are presented.
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Journal articleEdberg NJT, Boldu J, Eriksson AI, et al., 2026,
Solar Orbiter in Venus' ionosphere: observations from the 4th flyby
, Journal of Geophysical Research (JGR): Space Physics, Vol: 131, ISSN: 2169-9380Solar Orbiter entered the topside ionosphere of Venus for the first time when performing its 4th flyby of the planet, reaching an altitude of 378 km on 18 Feb 2025. High-cadence electron density measurements showed previously unresolved fine-structuring within plasma regions and boundaries, particularly at the ionopause. During the rapid flyby, a rare snapshot of the entire induced magnetosphere was captured during calm solar wind conditions around solar maximum. A well-structured and a relatively steady plasma environment was observed. Assuming an electron temperature of 0.5 eV, pressure balance was found across the ionopause, while at the same time quasi-periodic density and magnetic field variations suggest boundary oscillations. Near closest approach, non-force free magnetic flux ropes were observed. Small-scale perturbations in both magnetic field strength and density across them indicate them being dynamically evolving, rather than in a stationary state.
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Journal articleVecchio A, Maksimovic M, Galand MIF, et al., 2026,
Electron temperatures in the ionosphere of Venus from Solar Orbiter/Radio and Plasma Waves instrument
, Astronomy and Astrophysics (A & A), Vol: 709, ISSN: 0004-6361Context. On February 18, 2025, Solar Orbiter (SO) completed its fourth gravity assist maneuver of Venus (VGAM4) and reached an unprecedented proximity coming within 378 km of the planet. This flyby was necessary to steer the spacecraft into an orbit outside the plane of the ecliptic. Near the closest approach, only the Radio and Plasma Wave (RPW) and Magnetometer (MAG) instruments were operational; this enabled high-cadence measurements to be taken to investigate the plasma properties of the Venusian ionosphere.Aims. The main goal of this study is to derive the electron density and temperature in the ionosphere of Venus using electric potential measurements from RPW, and to characterize them.Methods. During approximately five minutes around the closest approach, the High Frequency Receiver of RPW detected radio emissions of a type naturally generated by planetary ionospheres whose frequency can be related to the electron density. Using quasithermal noise spectroscopy, we inferred the electron temperature at discrete altitudes and solar zenith angles.Results. Solar Orbiter measured an average density and electron temperature in the ionosphere of Venus of 12 385 ± 148 cm−3 and 0.43 ± 0.05 eV, respectively. These values are in agreement with in-situ measurements by Pioneer Venus Orbiter (PVO) obtained at the solar maximum. Binned magnetic fields and temperatures are anticorrelated, which suggests that the magnetic flux ropes, observed in the Venus ionosphere, are more likely non-force-free structures.Conclusions. The findings presented in this paper, together with the measurement from the Parker Solar Probe (PSP) during the third gravity assist, support the conclusion that the plasma density in the Venusian ionosphere above 350 km varies with solar activity, whereas the electron temperature shows a much weaker dependence. Notably, the electron temperature remains consistent across the three missions (SO, PSP, and PVO), despite varying levels of sola
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Journal articleWilson LB, Bale SD, Stevens ML, et al., 2026,
Electron Velocity Moments in the Solar Wind. I. Calibration of the Wind 3DP EESA Low Detector
, Astrophysical Journal Supplement Series, Vol: 284, ISSN: 0067-0049Calibrated measurements of electron velocity distribution functions (VDFs) are necessary to characterize fluid and kinetic processes in weakly collisional and nearly collisionless plasmas such as the solar wind. Therefore, we analyzed 3,996,051 electron VDFs observed by the Wind 3DP thermal electron detector near 1 au between 2005 January 1 and 2017 November 25. The data were calibrated for each electron VDF to produce accurate velocity moments in the solar wind. This is the first full solar cycle coverage electron velocity moment dataset in the near-Earth solar wind. Herein (Paper I) we discuss the calibration process/algorithms and the velocity moment constraints, uncertainties, and resulting public dataset. In the second paper (Paper II), we statistically analyze the electron velocity moment dataset.
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Journal articleLau KH, Czernichow S, Sparks N, et al., 2026,
A global parametric rain model for landfalling tropical cyclones: a case study for the U.S.
, Natural Hazards, Vol: 122, ISSN: 0921-030XRainfall associated with tropical cyclones (TCs) is a crucial driver of TC hazards, yet estimating TC rain risk from observations is hindered by their relative infrequency. Parametric TC rain models coupled with stochastic TC risk models provide an efficient mean for quantifying such risk. This study introduces a new parametric rain model for landfalling TCs, integrated into the Imperial College Storm Model (IRIS), a statistical-thermodynamic global TC hazard model. Using a 10,000-year simulation, IRIS reproduces observed global return periods of landfall rain rate, storm-total rain volume, and lifetime rain production over land. Over the United States, the model captures observed rainfall climatology and event accumulations with skill comparable to or slightly exceeding existing parametric models. The capability of the model for climate projection is demonstrated through a United States case study using a storyline approach that isolates thermodynamic effects, specifically increases in potential intensity and total column water, under a +2 °C global warming scenario. The pre-landfall maximum azimuthal mean rain rate of United States hurricanes increases by 20.1%, while contraction of the rain field limits the storm-total rain volume increase to 3.9%. Across their lifetimes over land, hurricanes produce 14.6% more rainfall. Spatially, warming enhances rain rates and accumulations across the eastern and southern United States, with the largest absolute increases in the southeast but the strongest relative increases inland and in the northeast, indicating greater inland and poleward penetration of hurricane rainfall under warming.
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Journal articleHorne RB, Angling MJ, Attrill GDR, et al., 2026,
The May 2024 geomagnetic storm: UK experience and perspective
, Royal Society Open Science, Vol: 13, ISSN: 2054-5703The May 2024 geomagnetic storm was the largest for over 20 years. The storm was categorized as a ‘low-level’ G5, where G5 is the highest on the National Oceanic and Atmospheric Administration (NOAA) scale for geomagnetic storms, yet the individual solar eruptive events were not particularly severe, and the observed impacts were relatively minor. The impacts that were observed were due to the combined and sustained effect of five successive earthward-directed coronal mass ejections (CMEs) which drove the storm. The event exposed the weakness of the current storm classification system which does not discriminate between low impact and high impact G5 events; it exercised the UK Met Office forecasting system, communications and UK preparedness; and it highlighted key areas that need to be addressed, particularly relating to national power supplies, space traffic management, aviation, forecasting and data gaps. Here, we set out what happened, record some of the key impacts, discuss what went well and what needs to be improved. We make 14 recommendations relevant to four government departments, so that the UK can be better prepared for a low-probability, high-impact space weather event described in the reasonable worst-case scenario that informs the national risk register.
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Journal articleFiedler S, O'Connor FM, Watson-Parris D, et al., 2026,
AerChemMIP2 – unraveling the role of reactive gases, aerosol particles, and land use for air quality and climate change in CMIP7
, Geoscientific Model Development, Vol: 19, Pages: 3477-3508, ISSN: 1991-959XPhase 2 of the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP2) is a registered model intercomparison project (MIP) of the Coupled Model Intercomparison Project phase 7 (CMIP7). The focus of AerChemMIP2 is the quantification of the atmospheric composition, biogeochemical feedbacks, air quality and climate responses to changes in emissions of chemically reactive gases, aerosol particles, and land use. AerChemMIP2 aims to facilitate a better understanding of their relative contributions to changes in atmospheric composition, radiative forcing, and the climate response and feedbacks from the pre-industrial period to the present day and for projected future emission pathways. Some experiments from the first phase of AerChemMIP are requested in the second phase to track changes in the results of CMIP7 compared to phase six of CMIP. New experiments in AerChemMIP2 open scientific opportunities to address knowledge gaps and persistent uncertainties. Specifically, AerChemMIP2 requests experiments (1) to assess the dependence of effective radiative forcing for aerosols on the fidelity of resolved processes and the simulated base climate, (2) to provide first estimates of forcing for hydrogen and individual volatile organic compounds in the context of CMIP, (3) to enable studies on non-linearity in the Earth system response, (4) to understand the response of wild fires to historical forcings, and (5) to quantify the influence of desert dust increases on climate change. AerChemMIP2 further requests variants of the ScenarioMIP-CMIP7 high-end and overshoot scenarios to quantify future responses to policy implementations for air quality management. Diagnostic requests of AerChemMIP2 are made from CMIP7 core experiments to facilitate offline experiments for chemistry and aerosols. The experimental protocol of AerChemMIP2 presented here closely aligns with the CMIP7 core experimental design, and its other registered MIPs. Selected AerChemMIP2 experiments are perform
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Journal articleErgun RE, Vo T, Qi Y, et al., 2026,
Evidence of a Subkinetic Spectral Break in a Strongly Turbulent Collisionless Plasma
, Astrophysical Journal, Vol: 1001, ISSN: 0004-637XWe investigate the magnetic (B) and electric (E) field spectra in the dissipation range of strong turbulence of a collisionless plasma. This investigation, which is relevant to turbulence studies in many astrophysical settings, is enabled by high-resolution measurements from the four-spacecraft Magnetospheric Multiscale (MMS) mission in the Earth’s magnetotail. B and E spectra are derived as a function of the product of the wave number and electron skin depth (|k| d<inf>e</inf>) using a novel technique that employs time-delay analysis on multiple intervals of B and E. Using the MMS tetrahedral formation with close (several d<inf>e </inf>) spacing, velocities of B and E signals can be derived so that native frequency-based spectra can be accurately translated to k spectra. The most important finding is a mathematically significant break in the B spectral index that appears at |k| d<inf>e</inf> ≈ 1. In the subion range, which spans from the ion inertial length (d<inf>ι </inf>) to d<inf>e </inf>, the B spectral index is −2.35, then steepens to − 3.13 at sub-d<inf>e </inf> scales. As expected from previously derived frequency spectra, E has a particularly shallow spectral index (−0.67) in the subion range. At scales smaller than d<inf>e </inf> and/or the electron thermal gyroradius (ρ<inf>e </inf>), the E spectral index steepens to −2.73. Spectral breaks in both B and E in the dissipation range indicate a change in the physical dissipation processes from ion to electron domination at |k| d<inf>e</inf> ≈ 1. We also confirm that at |k| ρ<inf>e</inf> > ~ 2, the energy density of B and E approaches equipartition, suggesting that energy transfer is near complete.
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Journal articleGuo J, Xie X, Myhre G, et al., 2026,
Distinct drivers of recent seasonal precipitation increase over Central Asia: roles of anthropogenic aerosols and greenhouse gases
, Atmospheric Chemistry and Physics, Vol: 26, Pages: 5169-5184, ISSN: 1680-7316Observational evidence reveals a pronounced wetting trend over Central Asia in recent decades, with the most substantial increases occurring during winter and summer. Yet the extent to which the drivers of these changes differ seasonally remains unknown. Here, we use single-forcing experiments from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP) to examine the effects of various external forcings on winter and summer precipitation across Central Asia and to explore the physical mechanisms underlying seasonal precipitation changes. We find that greenhouse gas (GHG) forcing mainly increases winter precipitation by enhancing atmospheric moisture content through warming. In contrast, in summer, Asian sulfate aerosols enhance precipitation by modulating the westerly jet, which strengthens atmospheric moisture transport into the region. Asian black carbon exerts an opposing influence that partially offsets the sulfate-induced effect. Further attribution analysis based on CMIP6 simulations reinforces these sensitivity results and shows that GHG forcing is the primary driver of winter precipitation increases whereas anthropogenic aerosols dominate summer trends. Future CMIP6 projections suggest that under moderate- to high-emission scenarios, winter precipitation will continue to rise due to increasing GHG concentrations, while summer precipitation may decline across much of Central Asia as a result of reduced aerosol emissions following Asian clean air policies. These findings highlight a distinct seasonality in the drivers of recent precipitation increase and suggest a plausible divergence in future winter and summer precipitation trends.
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