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Journal articleOwens MJ, Lockwood M, Barnard LA, et al., 2023,
Annual Variations in the Near-Earth Solar Wind
, SOLAR PHYSICS, Vol: 298, ISSN: 0038-0938 -
Journal articleArcher M, Southwood D, Hartinger M, et al., 2023,
Magnetosonic ULF waves with anomalous plasma - magnetic field correlations: standing waves and inhomogeneous plasmas
, Geophysical Research Letters, Vol: 50, Pages: 1-13, ISSN: 0094-8276Ultra-low frequency (ULF) wave observations across the heliosphere often rely on the sign of correlations between plasma (density/pressure) and magnetic field perturbations to distinguish between fast and slow magnetosonic modes. However, the assumptions behind this magnetohydrodynamic result are not always valid, particularly within the magnetosphere which is inhomogeneous and supports standing waves along the geomagnetic field. Through theory and a global simulation, we find both effects can result in anomalous plasma–magnetic field correlations. The interference pattern in standing waves can lead both body and surface magnetosonic waves to have different cross-phases than their constituent propagating waves. Furthermore, if the scale of gradients in the background are shorter than the wavelength or the waves are near-incompressible, then advection by the wave of inhomogeneities can overcome the wave's inherent sense of compression. These effects need to be allowed for and taken into account when applying the typical diagnostic to observations.
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Journal articleMurray-Watson R, Gryspeerdt E, Goren T, 2023,
Investigating the development of clouds within marine cold air outbreaks
, Atmospheric Chemistry and Physics, Vol: 23, Pages: 9365-9383, ISSN: 1680-7316Marine cold air outbreaks are important parts of the high-latitude climate system, and are characterised by strong surface fluxes generated by the air-sea temperature gradient. These fluxes promote cloud formation, which can be identified in satellite imagery by the distinct transformation of stratiform cloud ‘streets’ into a broken field of cumuliform clouds downwind of the outbreak. This evolution in cloud morphology changes the radiative properties of the cloud, and therefore is of importanceto the surface energy budget. While the drivers of stratocumulus-to-cumulus transitions, such as aerosols or the sea surface temperature gradient, have been extensively studied for subtropical clouds, the factors influencing transitions at higher latitudes are relatively poorly understood. This work uses reanalysis data to create a set of composite trajectories of cold air outbreaks moving off the Arctic ice edge and co-locates these trajectories with satellite data to generate a unique view of liquid-dominated cloud development within cold air outbreaks.The results of this analysis show that clouds embedded in cold-air outbreaks have distinctive properties relative to clouds following other trajectories in the region. The initial strength of the outbreak shows a lasting effect on cloud properties, with differences between clouds in strong and weak events visible over 30 hours after the air has left the ice edge. However, while the strength (measured by the magnitude of the marine cold-air outbreak index) of the outbreak affects the magnitude of cloud properties, it does not affect the timing of the transition to cumuliform clouds nor the top-of-atmosphere albedo. In contrast, the initial aerosol conditions do not strongly affect the magnitude of the cloud properties, but are correlated to cloud break-up,leading to an enhanced cooling effect in clouds moving through high aerosol conditions due to delayed break-up. Both the aerosol environment and the strength and
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Journal articleLi Y, Tang Y, Wang S, et al., 2023,
Recent increases in tropical cyclone rapid intensification events in global offshore regions
, Nature Communications, Vol: 14, ISSN: 2041-1723Rapid intensification (RI) is an essential process in the development of strong tropical cyclones and a major challenge in prediction. RI in offshore regions is more threatening to coastal populations and economies. Although much effort has been devoted to studying basin-wide temporal-spatial fluctuations, variations of global RI events in offshore regions remain uncertain. Here, we show that compared with open oceans, where the annual RI counts do not show significant changes, offshore areas within 400 km of the coastline have experienced a significant increase in RI events, with the count tripling from 1980 to 2020. Furthermore, thermodynamic environments present more favorable conditions for this trend, and climate models show that global ocean warming has enhanced such changes. This work yields an important finding that an increasing threat of RI in coastal regions has occurred in the preceding decades, which may continue under a future warming climate.
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Journal articleDaei F, Pomoell J, Price DJ, et al., 2023,
Modeling the formation and eruption of coronal structures by linking data-driven magnetofrictional and MHD simulations for AR 12673⋆
, ASTRONOMY & ASTROPHYSICS, Vol: 676, ISSN: 0004-6361- Author Web Link
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Journal articleTrotta D, Pezzi, Burgess D, et al., 2023,
Three-dimensional modelling of the shock-turbulence interaction
, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 525, Pages: 1856-1866, ISSN: 0035-8711 -
Journal articleHorbury T, Bale S, mcmanus M, et al., 2023,
Switchbacks, microstreams and broadband turbulence in the solar wind
, Physics of Plasmas, Vol: 30, ISSN: 1070-664XSwitchbacks are a striking phenomenon in near-Sun coronal hole flows, but their origins, evolution, and relation to the broadband fluctuations seen farther from the Sun are unclear. We use the near-radial lineup of Solar Orbiter and Parker Solar Probe during September 2020 when both spacecraft were in wind from the Sun's Southern polar coronal hole to investigate if switchback variability is related to large scale properties near 1 au. Using the measured solar wind speed, we map measurements from both spacecraft to the source surface and consider variations with source Carrington longitude. The patch modulation of switchback amplitudes at Parker at 20 solar radii was associated with speed variations similar to microstreams and corresponds to solar longitudinal scales of around 5°–10°. Near 1 au, this speed variation was absent, probably due to interactions between plasma at different speeds during their propagation. The alpha particle fraction, which has recently been shown to have spatial variability correlated with patches at 20 solar radii, varied on a similar scale at 1 au. The switchback modulation scale of 5°–10°, corresponding to a temporal scale of several hours at Orbiter, was present as a variation in the average deflection of the field from the Parker spiral. While limited to only one stream, these results suggest that in coronal hole flows, switchback patches are related to microstreams, perhaps associated with supergranular boundaries or plumes. Patches of switchbacks appear to evolve into large scale fluctuations, which might be one driver of the ubiquitous turbulent fluctuations in the solar wind.
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Journal articleZazzeri G, Graven H, Xu X, et al., 2023,
Radiocarbon measurements reveal underestimated fossil CH₄ and CO₂ emissions in London
, Geophysical Research Letters, Vol: 50, ISSN: 0094-8276Radiocarbon (14C) is a powerful tracer of fossil emissions because fossil fuels are entirely depleted in 14C, but observations of 14CO2 and especially 14CH4 in urban regions are sparse. We present the first observations of 14C in both methane (CH4) and carbon dioxide (CO2) in an urban area (London) using a recently developed sampling system. We find that the fossil fraction of CH4 and the atmospheric concentration of fossil CO2 are consistently higher than simulated values using the atmospheric dispersion model NAME coupled with emission inventories. Observed net biospheric uptake in June–July is not well correlated with simulations using the SMURF model with NAME. The results show the partitioning of fossil and biospheric CO2 and CH4 in cities can be evaluated and improved with 14C observations when the nuclear power plants influence is negligible.
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Journal articleLivi S, Lepri ST, Raines JM, et al., 2023,
First results from the Solar Orbiter Heavy Ion Sensor
, ASTRONOMY & ASTROPHYSICS, Vol: 676, ISSN: 0004-6361 -
Journal articleHeyns MJ, Lotz SI, Cilliers PJ, et al., 2023,
Adaptations to a geomagnetic field interpolation method in Southern Africa
, ADVANCES IN SPACE RESEARCH, Vol: 72, Pages: 854-865, ISSN: 0273-1177 -
Journal articleZhu X, He J, Duan D, et al., 2023,
Non-field-aligned Proton Beams and Their Roles in the Growth of Fast Magnetosonic/Whistler Waves: Solar Orbiter Observations
, ASTROPHYSICAL JOURNAL, Vol: 953, ISSN: 0004-637X -
Journal articleZimbardo G, Ying B, Nisticò G, et al., 2023,
A high-latitude coronal mass ejection observed by a constellation of coronagraphs: Solar Orbiter/Metis, STEREO-A/COR2, and SOHO/LASCO
, Astronomy and Astrophysics, Vol: 676, ISSN: 0004-6361Context. A few days before the first perihelion of the Solar Orbiter nominal mission, which occurred on 2022 March 26, the Metis coronagraph on board Solar Orbiter detected a coronal mass ejection (CME) that was moving away from the far side of the Sun (with respect to Solar Orbiter) at high northern latitudes. The eruption was also seen by other spacecraft, in particular, by STEREO-A, which was in quadrature configuration with Solar Orbiter. Aims. We analyse the different views of the CME by a constellation of spacecraft with the purpose to determine the speed and acceleration of the CME, and to identify the source region of the CME. Methods. Considering the positions of various spacecraft on 2022 March 22, this CME happened to be within the field of view of STEREO-A/SECCHI, and it was visible over the limb from SOHO/LASCO. We present the results of the 3D reconstruction of the CME based on the graduated cylindrical shell model and of the identification of the possible origin of the CME using extreme-ultraviolet (EUV) observations by Solar Orbiter/EUI, STEREO-A/EUVI, and SDO/AIA. The observations in EUV are compared with the coronal magnetic structure obtained by the potential field source surface method. Results. The 3D reconstruction of the CME derives a central latitude of 29 N, a Stonyhurst longitude of 125, and an average radial speed at the apex of 322 ± 33 km s1 between 4 and 13 RȮ, which is probably not high enough to generate a shock wave. The estimated average acceleration of the CME is 16 ± 11 m s2 in the same range of distances from the Sun. This CME may be associated with the disappearance of a coronal cloud prominence, which is seen in the EUV by STEREO-A/EUVI and SDO/AIA, and is also associated with rapidly evolving emerging magnetic flux.
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Journal articleMisal H, Varela E, Voulgarakis A, et al., 2023,
Assessing public preferences for a wildfire mitigation policy in Crete, Greece
, Forest Policy and Economics, Vol: 153, Pages: 1-16, ISSN: 1389-9341The increased frequency and severity of wildfires in the Mediterranean region generates significant damages in ecosystems and landscapes while harming human populations. Institutional complexities, along with socioeconomic and demographic changes encouraging development into the wildland-urban interface, rural abandonment, and focus on fire suppression, are increasing the vulnerability and flammability of Mediterranean ecosystems. Developing effective strategies for managing wildfire incidence and its aftermath requires understanding of the public preferences for wildfire policy characteristics. Here we elicit public preferences for wildfire mitigation policies employing a stated choice experiment applied in Crete, Greece. A region with typical Mediterranean landscape experiencing significant development and rural-to-urban migration that disrupts existing fire regimes. We estimate conditional logit, mixed logit and latent class models to study the general public's preferences and willingness to pay for limiting wildfire frequency and agricultural land burnt, maintaining landscape features, and managing post-wildfire recovery. Results of our study show that measures to manage post-wildfire damage are consistently valued as the most positive amongst the sampled respondents, achieving values that range between €25.92 in conditional logit model to €46 in one of the latent classes identified. Improving the landscape quality follows in importance, although it shows more heterogeneity in the responses. The latent class approach allowed to identify that those associated with either the agricultural or the tourism sector of the sampled individuals, displayed significantly different preferences for the proposed attributes. Overall, our findings indicate that there is a strong preference amongst the general public to shift current policies based on suppression towards more integrated approaches dealing both with prevention and post-fire management. The outcomes of th
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Journal articleRoberts OW, Voeroes Z, Torkar K, et al., 2023,
Estimation of the Error in the Calculation of the Pressure-Strain Term: Application in the Terrestrial Magnetosphere
, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 128, ISSN: 2169-9380 -
Journal articleUsanova ME, Ergun RE, Stawarz JE, 2023,
Ion Energization by Turbulent Electric Fields in Fast Earthward Flows and Its Implications for the Dynamics of the Inner Magnetosphere
, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 128, ISSN: 2169-9380 -
Journal articleLewis HC, Stawarz JE, Franci L, et al., 2023,
Magnetospheric Multiscale measurements of turbulent electric fields in earth's magnetosheath: How do plasma conditions influence the balance of terms in generalized Ohm's law?
, PHYSICS OF PLASMAS, Vol: 30, ISSN: 1070-664X -
Journal articleVuorinen L, LaMoury AT, Hietala H, et al., 2023,
Magnetosheath Jets Over Solar Cycle 24: An Empirical Model
, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 128, ISSN: 2169-9380 -
Journal articleKilpua E, Vainio R, Cohen C, et al., 2023,
Energetic ion enhancements in sheaths driven by interplanetary coronal mass ejections
, ASTROPHYSICS AND SPACE SCIENCE, Vol: 368, ISSN: 0004-640X -
Journal articleAdhikari S, Shay M, Parashar T, et al., 2023,
Effect of a guide field on the turbulence like properties of magnetic reconnection
, Physics of Plasmas, Vol: 30, Pages: 1-14, ISSN: 1070-664XThe effect of an external guide field on the turbulence-like properties of magneticreconnection is studied using five different 2.5D kinetic particle-in-cell (PIC) simulations. The magnetic energy spectrum is found to exhibit a slope of approximately−5/3 in the inertial range, independent of the guide field. On the contrary, theelectric field spectrum, in the inertial range steepens more with the guide field andapproaches a slope of −5/3. In addition, spectral analysis of the different terms ofthe generalized Ohm’s law is performed and found to be consistent with PIC simulations of turbulence and MMS observations. Finally, the guide field effect on theenergy transfer behavior is examined using von-K´arm´an Howarth (vKH) equationbased on incompressible Hall-MHD. The general characteristics of the vKH equationwith constant rate of energy transfer in the inertial range, is consistent in all the simulations. This suggests that the qualitative behavior of energy spectrum, and energytransfer in reconnection is similar to that of turbulence, indicating that reconnectionfundamentally involves an energy cascade.
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Journal articleLewis ZM, Beth A, Altwegg K, et al., 2023,
Origin and trends in NH4+ observed in the coma of 67P
, Monthly Notices of the Royal Astronomical Society, Vol: 523, Pages: 6208-6219, ISSN: 0035-8711The European Space Agency/Rosetta mission escorted comet 67P/Churyumov–Gerasimenko and witnessed the evolution of its coma from low activity (∼2.5–3.8 au) to rich ion-neutral chemistry (∼1.2–2.0 au). We present an analysis of the ion composition in the coma, focusing on the presence of protonated high proton affinity (HPA) species, in particular NH4+. This ion is produced through the protonation of NH3 and is an indicator of the level of ion-neutral chemistry in the coma. We aim to assess the importance of this process compared with other NH4+ sources, such as the dissociation of ammonium salts embedded in dust grains. The analysis of NH4+ has been possible thanks to the high mass resolution of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/Double Focusing Mass Spectrometer (ROSINA/DFMS). In this work, we examine the NH4+ data set alongside data from the Rosetta Plasma Consortium instruments, and against outputs from our in-house ionospheric model. We show that increased comet outgassing around perihelion yields more detections of NH4+ and other protonated HPA species, which results from more complex ion-neutral chemistry occurring in the coma. We also reveal a link between the low magnetic field strength associated with the diamagnetic cavity and higher NH4+ counts. This suggests that transport inside and outside the diamagnetic cavity is very different, which is consistent with 3D hybrid simulations of the coma: non-radial plasma dynamics outside the diamagnetic cavity is an important factor affecting the ion composition.
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Journal articleGrimmich N, Plaschke F, Archer MO, et al., 2023,
Study of extreme magnetopause distortions under varying solar wind conditions
, JGR: Space Physics, Vol: 128, Pages: 1-22, ISSN: 2169-9402To first order, the magnetopause (MP) is defined by a pressure balance between the solar wind and the magnetosphere. The boundary moves under the influence of varying solar wind conditions and transient foreshock phenomena, reaching unusually large and small distances from the Earth. We investigate under which solar wind conditions such extreme MP distortions occur. Therefore, we construct a database of magnetopause crossings (MPCs) observed by the THEMIS spacecraft in the years 2007 to mid-2022 using a simple Random Forest Classifier. Roughly 7% of the found crossing events deviate beyond reported errors in the stand-off distance from the Shue et al. (1998, https://doi.org/10.1029/98JA01103) MP model and thus are termed extreme distortions. We find the occurrence of these extreme events in terms of expansion or compression of the MP to be linked to different solar wind parameters, most notably to the IMF magnitude, cone angle, velocity, Alfvén Mach number and temperature. Foreshock transients like hot-flow anomalies and foreshock bubbles could be responsible for extreme magnetospheric expansions. The results should be incorporated into future magnetopause models and may be helpful for the reconstruction of the MP locations out of soft x-ray images, relevant for the upcoming SMILE mission.
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Journal articleWilson L, Goodrich K, Turner D, et al., 2023,
The necessity of accurate measurements of thermal velocity distribution functions in the solar wind
, Bulletin of the AAS -
Journal articleWimmer-Schweingruber RF, André N, Barabash S, et al., 2023,
STELLA — In situ Investigations of the Very Local Interstellar Medium
, Bulletin of the AAS -
Journal articleChen L-J, Spence H, Klein K, et al., 2023,
Plasma turbulence: Challenges and next transformative steps from the perspective of multi-spacecraft measurements
, Bulletin of the AAS -
Journal articleHalford AJ, Stawarz JE, Allen RC, et al., 2023,
An Inclusive Heliophysics Community
, Bulletin of the AAS -
Journal articleArridge CS, Xystouris G, Cochrane C, et al., 2023,
Fundamental Space Physics in Uranus’ Magnetosphere
, Bulletin of the AAS -
Journal articleGoodrich K, Schwartz S, III LW, et al., 2023,
The Persistent Mystery of Collisionless Shocks
, Bulletin of the AAS -
Journal articleHalford AJ, Stawarz JE, Allen RC, et al., 2023,
Mentorship within Heliophysics
, Bulletin of the AAS -
Journal articleHalford AJ, Stawarz JE, Dong C, et al., 2023,
The Importance of Policies: It’s not just a pipeline problem
, Bulletin of the AAS -
Journal articleMontgomery J, Ebert R, Allegrini F, et al., 2023,
Investigating the occurrence of Kelvin-Helmholtz instabilities at Jupiter’s dawn magnetopause
, Geophysical Research Letters, Vol: 50, ISSN: 0094-8276We use the Kelvin-Helmholtz instability (KHI) condition with particle and magnetic field observations from Jovian Auroral Distributions Experiment and MAG on Juno along the dawn flank of Jupiter's magnetosphere. We identify the occurrence of magnetopause crossings that show evidence of being KH (Kelvin-Helmholtz) unstable. When estimating the k vector to be parallel to the velocity shear, we find that 25 of 62 (40%) magnetopause crossings satisfy the KHI condition. When considering the k vector of the maximum growth rate through a solid angle approach, we find that 60 of 62 (97%) events are KH unstable. This study shows evidence of KH waves at Jupiter's dawn flank, including primary drivers such as high velocity shears and changes in plasma pressure. Signatures of magnetic reconnection were also observed in ∼25% of the KH unstable crossings. We discuss these results and their implication for the prevalence of KHI at Juno's dawn magnetopause as measured by Juno.
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