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Journal articleMaunder M, Foullon C, Forsyth R, et al., 2025,
Longitudinally Spaced Observations of a Magnetic Cloud-Like Structure Embedded in a Co-rotating Interaction Region
, Annales Geophysicae: atmospheres, hydrospheres and space sciences, ISSN: 0992-7689 -
Journal articleD'amicis R, Velli M, Panasenco O, et al., 2025,
On Alfvénic turbulence of solar wind streams observed by Solar Orbiter during March 2022 perihelion and their source regions
, Astronomy and Astrophysics, Vol: 693, ISSN: 0004-6361Context. It has been recently accepted that the standard classification of the solar wind solely according to flow speed is outdated, and particular interest has been devoted to the study of the origin and evolution of so-called Alfvénic slow solar wind streams and to what extent such streams resemble or differ from fast wind. Aims. In March 2022, Solar Orbiter completed its first nominal phase perihelion passage. During this interval, it observed several Alfvénic streams, allowing for characterization of fluctuations in three slow wind intervals (AS1-AS3) and comparison with a fast wind stream (F) at almost the same heliocentric distance. Methods. This work makes use of Solar Orbiter plasma parameters from the Solar Wind Analyzer (SWA) and magnetic field measurements from the magnetometer (MAG). The magnetic connectivity to the solar sources of selected solar wind intervals was reconstructed using a ballistic extrapolation based on measured solar wind speed down to the (spherical) source surface at 2.5 Rs below which a potential field extrapolation was used to map back to the Sun. The source regions were identified using SDO/AIA observations. A spectral analysis of in situ measured magnetic field and velocity fluctuations was performed to characterize correlations, Alfvénicity, normalized cross-helicity, and residual energy in the frequency domain as well as intermittency of the fluctuations and spectral energy transfer rate estimated via mixed third-order moments. A machine learning technique was used to separate proton core, proton beam, and alpha particles and to study v-b correlations for the different ion populations in order to evaluate the role played by each population in determining the Alfvénic content of solar wind fluctuations. Results. The comparison between fast wind and Alfvénic slow wind intervals highlights the differences between the two solar wind regimes: The fast wind is characterized by larger amplitude fluct
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Journal articleHall RJ, Czaja A, Danabasoglu G, et al., 2025,
A new robust frontal disturbance index of the Oyashio Extension sea surface temperature front
, Journal of Climate, Vol: 38, Pages: 293-307, ISSN: 0894-8755The Oyashio Extension (OE) frontal zone in the northwest Pacific Ocean is associated with strong gradients of sea surface temperature (SST) and salinity. The OE front enhances baroclinicity and anchors the storm tracks; changes in its position and strength may impact atmospheric variability. North–south shifts in the OE front are often defined using the leading principal component for the latitude of the absolute maximum SST gradient in the northwest Pacific (145°–170°E), the so-called Oyashio Extension index (OEI). We show that the OEI is sensitive to the choice of SST dataset used in its construction, and that the significance of regressions of atmospheric fields onto the OEI also depends on the choice of SST datasets, leading to nonrobust results. This sensitivity primarily stems from the longitudinal domain used to define the OEI including a region with parallel or indistinct frontal zones in its central section (155°–164°E), leading to divergent results across datasets. We introduce a new index that considers the extent to which the SST front across this central section departs from climatology, the frontal disturbance index (FDI). For the months considered and over short time lags, the FDI produces more consistent results on air–sea interactions and associated high-frequency storm-track metrics than the conventional OEI, with a southward shift of the storm track for a more positive FDI. The FDI appears to be related to oceanic mesoscale eddy activity in the central OE region. There are significant asymmetric associations between the FDI and storm-track metrics dependent on the sign of the FDI.
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Journal articleMauel M, Bale SD, Fox NJ, et al., 2025,
Preface to special topic: Plasma physics of the Sun in honor of Eugene Parker
, Physics of Plasmas, Vol: 32, ISSN: 1070-664XThis Special Topic commemorates the legacy of Eugene Parker and highlights new understandings of the plasma physics of the Sun resulting from the observations, plans, and analyses for the Parker Solar Probe (PSP) and Solar Orbiter (SolO) Missions. In recognition of Eugene Parker's remarkable insights and many contributions, distinguished authors from around the world were invited to present papers in theoretical, computational, and observational heliophysics and astrophysics. A total of 80 authors from 12 countries (Argentina, Czech Republic, France, Germany, Greece, India, Italy, New Zealand, People's Republic of China, Spain, United Kingdom, and United States of America) contributed to the Special Collection. These papers bring the recent research in physics of the Sun to the broader plasma physics community. Many include the latest observations from PSP and SolO and describe new understandings of coronal processes, solar wind structure and dynamics, transient events including nanoflares, and insights into stellar equilibrium and flows.
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Journal articleLai T, Toumi R, 2025,
Sensitivity of the energy conversion efficiency of tropical cyclones during intensification to sea surface temperature and static stability
, Quarterly Journal of the Royal Meteorological Society, Vol: 151, ISSN: 0035-9009It is projected that the sea surface temperature (SST) increases under climate change and enhances tropical cyclone (TC) intensification directly. An opposing expected feature of climate change is the strengthening atmospheric static stability, which may suppress intensification. The intensity and diabatic heating are closely related through the secondary circulation, but it has been unclear whether both will change at the same rate. Here we show that they respond differently to stability changes. The efficiency of converting diabatic heating to kinetic energy (KE) of TCs to SST and static stability during the intensification stage is examined. In a set of idealised simulations, the efficiency does not have a significant relation with the SST. However the efficiency is found to decrease with increasing static stability at a rate of about -5 % ⋅K‾¹. It is shown that the KE increment declines, while the diabatic heating in the eyewall remains unchanged with larger static stability. The decrease in KE gain at the eyewall is associated with an enhanced outward advection of absolute angular momentum. The combined effect of enhanced water‐vapour supply and the slightly reduced updraft at the eyewall keeps the diabatic heating steady with varying static stability. This study demonstrates the complex effects of enhanced static stability, which is expected to accompany surface warming, on tropical cyclones.
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Book chapterGaland M, Carnielli G, Jia X, 2025,
The ionosphere of Ganymede
, Ganymede, Editors: Volwerk, McGrath, Jia, Spohn, Publisher: Cambridge University Press, Pages: 269-289, ISBN: 9781108966474 -
Book chapterGalli A, Vorburger A, Wurz P, et al., 2025,
Interactions between the space environment and Ganymede’s surface
, Ganymede, Editors: Volwerk, McGrath, Jia, Spohn, Publisher: Cambridge University Press, Pages: 237-251, ISBN: 9781108966474 -
Journal articleAcevski M, Masters A, 2024,
Enhanced precipitation of energetic protons due to Uranus' asymmetric magnetic field
, Geophysical Research Letters, Vol: 51, ISSN: 0094-8276Uranus remains one of the most unexplored planets in our solar system, featuring a distinctive magnetic field structure first observed by NASA's Voyager 2 mission almost 40 years ago. Uranus is particularly notable for its pronounced magnetic field asymmetry, a characteristic unique to the icy giants. Here we show that, in the region where Voyager 2 did not pass (< 4 Ru), the asymmetric magnetic field can distort the trajectories of high energy protons within Uranus' radiation belts such that the particles hit the planet when they otherwise would not have (in a traditional dipole field). This implies that radiation belt protons which start with pitch angles well outside their respective loss cones can drift into a region where the loss cone is much bigger and then precipitate. This occurs preferentially in the magnetic north pole due to its significantly weaker surface field strength.
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Journal articleLewis HC, Stawarz JE, Matteini L, et al., 2024,
Turbulent Energy Conversion Associated With Kinetic Microinstabilities in Earth's Magnetosheath
, GEOPHYSICAL RESEARCH LETTERS, Vol: 51, ISSN: 0094-8276 -
Journal articleHarrison JA, Pearce PM, Yang F, et al., 2024,
Evaluating potential power output of terrestrial thermoradiative diodes with atmospheric modelling
, iScience, Vol: 27, ISSN: 2589-0042A thermoradiative diode is a device that can generate power through thermal emission from the warm Earth to the cold night sky. Accurate assessment of the potential power output requires knowledge of the downwelling radiation from the atmosphere. Here, accurate modelling of this radiation is used alongside a detailed balance model of a diode at the Earth’s surface temperature to evaluate its performance under nine different atmospheric conditions. In the radiative limit, these conditions yield power densities between 0.34 and 6.5 W.m-2, with optimal bandgaps near 0.094 eV. Restricting the angles of emission and absorption to less than a full hemisphere can marginally increase the power output. Accounting for non-radiative processes, we suggest that if a 0.094 eV device would have radiative efficiencies more than two orders of magnitude lower than a diode with a bandgap near 0.25 eV, the higher bandgap material is preferred.
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Journal articleSilvy Y, Frölicher TL, Terhaar J, et al., 2024,
AERA-MIP: emission pathways, remaining budgets, and carbon cycle dynamics compatible with 1.5 and 2 °C global warming stabilization
, Earth System Dynamics, Vol: 15, Pages: 1591-1628, ISSN: 2190-4979While international climate policies now focus on limiting global warming to well below 2 °C or pursuing a 1.5 °C level of global warming, the climate modelling community has not provided an experimental design in which all Earth system models (ESMs) converge and stabilize at the same prescribed global warming levels. This gap hampers accurate estimations based on comprehensive ESMs of the carbon emission pathways and budgets needed to meet such agreed warming levels and of the associated climate impacts under temperature stabilization. Here, we apply the Adaptive Emission Reduction Approach (AERA) with ESMs to provide such simulations in which all models converge at 1.5 and 2.0 °C warming levels by adjusting their emissions over time. These emission-driven simulations provide a wide range of emission pathways and resulting atmospheric CO2 projections for a given warming level, uncovering uncertainty ranges that were previously missing in the traditional Coupled Model Intercomparison Project (CMIP) scenarios with prescribed greenhouse gas concentration pathways. Meeting the 1.5 °C warming level requires a 40 % (full model range: 7 % to 76 %) reduction in multi-model mean CO2-forcing-equivalent (CO2-fe) emissions from 2025 to 2030, a 98 % (57 % to 127 %) reduction from 2025 to 2050, and a stabilization at 1.0 (-1.7 to 2.9) PgC yr-1 from 2100 onward after the 1.5 °C global warming level is reached. Meeting the 2.0 °C warming level requires a 47 % (8 % to 92 %) reduction in multi-model mean CO2-fe emissions until 2050 and a stabilization at 1.7 (-1.5 to 2.7) PgC yr-1 from 2100 onward. The on-average positive emissions under stabilized global temperatures are the result of a decreasing transient climate response to cumulative CO2-fe emissions over time under stabilized global warming. This evolution is consistent with a slightly negative zero emissions commitment - initially assumed to be zero - and leads to an increase in the post-2025 CO2-fe em
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Journal articleHuang Z, Velli M, Shi C, et al., 2024,
Dominance of 2 Minute Oscillations near the Alfven Surface
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 977, ISSN: 2041-8205 -
Journal articleDing M, Kozuki H, Concepcion F, et al., 2024,
Laboratory confirmation and improved accuracy of 4f and 5d energy levels of Fe ii previously identified from stellar spectra
, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 536, Pages: 274-279, ISSN: 0035-8711 -
Journal articleTippett A, Gryspeerdt E, Manshausen P, et al., 2024,
Weak liquid water path response in ship tracks
, Atmospheric Chemistry and Physics, Vol: 24, Pages: 13269-13283, ISSN: 1680-7316The assessment of aerosol–cloud interactions remains a major source of uncertainty in understanding climate change, partly due to the difficulty in making accurate observations of aerosol impacts on clouds. Ships can release large numbers of aerosols that serve as cloud condensation nuclei, which can create artificially brightened clouds known as ship tracks. These aerosol emissions offer a “natural”, or “opportunistic”, experiment to explore aerosol effects on clouds, while also disentangling meteorological influences. Utilizing ship positions and reanalysis wind fields, we predict ship track locations, colocating them with satellite data to depict the temporal evolution of cloud properties after an aerosol perturbation. Repeating our analysis for a null experiment does not necessarily recover zero signal as expected; instead, it reveals subtleties between different null-experiment methodologies. This study uncovers a systematic bias in prior ship track research, due to the assumption that background gradients will, on average, be linear. We correct for this bias, which is linked to the correlation between wind fields and cloud properties, to reveal the true ship track response.We find that, once this bias is corrected for, the liquid water path (LWP) response after an aerosol perturbation is weak on average. This has important implications for estimates of radiative forcings due to LWP adjustments, as previous responses in unstable cases were overestimated. A noticeable LWP response is only recovered in specific cases, such as marine stratocumulus clouds, where a positive LWP response is found in precipitating or clean clouds. This work highlights subtleties in the analysis of isolated opportunistic experiments, reconciling differences in the LWP response to aerosols reported in previous studies.
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Book chapterBeth A, Galand M, Simon Wedlund C, et al., 2022,
Cometary Ionospheres: An Updated Tutorial
, Comets III, Editors: Meech, Combi, Bockelée-Morvan, Raymond, Zolensky, Publisher: University of Arizona Press, ISBN: 9780816553648This chapter aims at providing the tools and knowledge to understand and model the plasma environment surrounding comets in the innermost part near the nucleus. In particular, our goal is to give an updated post-Rosetta view of this ionised environment: what we knew, what we confirmed, what we overturned, and what we still do not understand.
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Journal articleHanna E, Francis J, Wang M, et al., 2024,
Influence of high-latitude blocking and the northern stratospheric polar vortex on cold-air outbreaks under Arctic amplification of global warming
, ENVIRONMENTAL RESEARCH-CLIMATE, Vol: 3 -
Journal articleRovithakis A, Voulgarakis A, 2024,
Wildfire aerosols and their impact on weather: a case study of the August 2021 fires in Greece using the WRF‐Chem model
, Atmospheric Science Letters, Vol: 25, ISSN: 1530-261XWildfires are significant contributors to atmospheric gases and aerosols, impacting air quality and composition. This pollution from fires also affects radiative forcing, influencing short-term weather patterns and climate dynamics. Our research employs the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to investigate the repercussions of wildfires on aerosol abundances and associated immediate weather responses. We examine the summer season of 2021, a period marked by severe wildfire events in the country during a heatwave period. We conducted sensitivity experiments including and excluding wildfire emissions to measure their effects on aerosol optical depth (AOD), radiative forcing, and weather features such as temperature, humidity, clouds, and atmospheric circulation. Our findings demonstrate that the radiative impacts of wildfires negatively influence the local temperature over the fire smoke plume-affected areas. Conversely, neighbouring areas of continental Greece experience increases in temperature due to remote effects of wildfire emissions, caused by meteorological feedbacks that reduce atmospheric humidity. Crucially, including fire emissions significantly improves the simulated surface temperatures predicted by the model over the Greek domain. Our work demonstrates that wildfire-generated aerosols can significantly impact weather conditions and highlights the importance of including both local radiative effects and remote feedback for achieving more accurate weather prediction.
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Journal articleDing M, Ryabtsev AN, Kononov EY, et al., 2024,
Spectrum and energy levels of the high-lying singly excited configurations of Nd III: New Nd III experimental energy levels and wavelengths, with transition probability and ionisation energy calculations
, ASTRONOMY & ASTROPHYSICS, Vol: 692, ISSN: 0004-6361 -
Journal articleNykyri K, Di Matteo S, Archer MO, et al., 2024,
Could a low‐frequency perturbation in the Earth's magnetotail be generated by the lunar wake?
, Geophysical Research Letters, Vol: 51, ISSN: 0094-8276Both ground based magnetometers and ionospheric radars at Earth have frequently detected Ultra Low Frequency (ULF) fluctuations at discrete frequencies extending below one mHz-range. Many dayside solar wind drivers have been convincingly demonstrated as driver mechanisms. In this paper we investigate and propose an additional, nightside generation mechanism of a low frequency magnetic field fluctuation. We propose that the Moon may excite a magnetic field perturbation of the order of 1 nT at discrete frequencies when it travels through the Earth's magnetotail 4–5 days every month. Our theoretical prediction is supported by a case study of ARTEMIS magnetic field measurements at the lunar orbit in the Earth's magnetotail. ARTEMIS detects statistically significant peaks in magnetic field fluctuation power at frequencies of 0.37–0.47 mHz that are not present in the solar wind.
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Journal articleZeng Z, Yao Z, Liu J, et al., 2024,
Ultralow-frequency waves in Jupiter’s magnetopause boundary layer
, The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 976, ISSN: 0004-637XUltralow-frequency (ULF) waves (∼tens of minutes period) are widely identified in the Jovian system and are believed to be associated with energy dissipation in the magnetosphere and ionosphere. Due to the magnetodisk oscillation related to planetary rotation, it is challenging to identify the periodicities inside the magnetosphere, although remote sensing observations of the polar emissions provide clear evidence of the tens of minutes pulsations. In this study, we take advantage of Juno's in situ measurements in the magnetopause boundary layer for a long duration, i.e., >4 hr, to directly assess the tens of minutes periodicities of the boundary dynamics caused by the interactions between the internal plasma and external solar wind. Through periodogram analysis on the magnetic field and particle data, we find ULF waves with periodicities of ∼18 minutes, ∼40 minutes, and ∼70–80 minutes, which is generally consistent with pulsations in multiple remote sensing observations. A multiple-harmonic ULF phenomenon was also identified in the observations. The periodicities from in situ measurements provide crucial clues in understanding the origin of pulsating wave/auroral emissions in the Jovian system. The results could also further our understanding of energy transfer and release between the internal plasma of Jupiter and external solar wind.
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Journal articleOpie S, Verscharen D, Chen CHK, et al., 2024,
Temperature anisotropy instabilities driven by intermittent velocity shears in the solar wind
, JOURNAL OF PLASMA PHYSICS, Vol: 90, ISSN: 0022-3778 -
Journal articleErvin T, Jaffarove K, Badman ST, et al., 2024,
Characteristics and Source Regions of Slow Alfvénic Solar Wind Observed by Parker Solar Probe
, ASTROPHYSICAL JOURNAL, Vol: 975, ISSN: 0004-637X -
Journal articleChen L, Ma B, Wu D, et al., 2024,
Spectral Characteristics of Fundamental-Harmonic Pairs of Interplanetary Type III Radio Bursts Observed by PSP
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 975, ISSN: 2041-8205 -
Journal articleJebaraj IC, Agapitov OV, Gedalin M, et al., 2024,
Direct Measurements of Synchrotron-emitting Electrons at Near-Sun Shocks
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 976, ISSN: 2041-8205 -
Journal articleLario D, Balmaceda LA, Gomez-Herrero R, et al., 2024,
A Rapid Sequence of Solar Energetic Particle Events Associated with a Series of Extreme-ultraviolet Jets: Solar Orbiter, STEREO-A, and Near-Earth Spacecraft Observations
, ASTROPHYSICAL JOURNAL, Vol: 975, ISSN: 0004-637X -
Journal articleBessho N, Chen L-J, Hesse M, et al., 2024,
Electron Acceleration in Magnetic Islands in Quasi-parallel Shocks
, ASTROPHYSICAL JOURNAL, Vol: 975, ISSN: 0004-637X -
Journal articleBlyth L, Graven H, Manning AJ, et al., 2024,
Radiocarbon as a tracer of the fossil fraction of regional carbon monoxide emissions
, ENVIRONMENTAL RESEARCH LETTERS, Vol: 19, ISSN: 1748-9326 -
Journal articleEllmeier M, Betzler A, Amtmann C, et al., 2024,
Lower magnetic field measurement limit of the coupled dark state magnetometer
, MEASUREMENT SCIENCE AND TECHNOLOGY, Vol: 35, ISSN: 0957-0233 -
Journal articleMasters A, 2024,
Solar wind power likely governs Uranus’ thermosphere temperature
, Geophysical Research Letters, Vol: 51, ISSN: 0094-8276Observations of Uranus in the near-infrared by ground-based telescopes from 1992 to 2018 have shown that the planet's upper atmosphere (thermosphere) steadily cooled from ∼700 to ∼450 K. We explain this cooling as due to the concurrent decline in the power of the solar wind incident on Uranus' magnetic field, which has dropped by ∼50% over the same period due to solar activity trends longer than the 11-year solar cycle. Uranus' thermosphere appears to be more strongly governed by the solar wind than any other planet where we have assessed this coupling so far. Uranus' total auroral power may also have declined, in contrast with the power of the radio aurora that we expect has been predominantly modulated by the solar cycle. In the absence of strong local driving, planets with sufficiently large magnetospheres may also have thermospheres predominantly governed by the stellar wind, rather than stellar radiation.
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Journal articleChakravorty S, Czaja A, Parfitt R, et al., 2024,
Tropospheric response to gulf stream intrinsic variability: a model ensemble approach
, Geophysical Research Letters, Vol: 51, ISSN: 0094-8276The Gulf Stream's (GS) impact on the marine boundary layer (MBL) is well established, yet the mechanisms and timescales through which it affects the upper-troposphere and contributes to precipitation are debatable. Using a high-resolution regional atmospheric model, we shed light on the impact of ocean intrinsic variability (OIV) along GS on midlatitude-atmosphere. Taking advantage of a 24-member ensemble of ocean model integrations, we devised a novel experimental setup where the same weather system feels different realizations of GS sea surface temperature (SST). We introduce the “Eddy Recharge-Frontal Lift” (ERFL) mechanism, highlighting the joint importance of synoptic variability and boundary layer processes. ERFL mechanism proposes that OIV recharges/discharges MBL with moisture and heat, while convergence associated with passing atmospheric-fronts uplifts these MBL-trapped anomalies to upper-troposphere and imprints on precipitation in surprisingly short periods (a month). The impact of OIV on precipitation depends on the background mean SST.
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