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Journal articleArcher M, Waters C, Dewan S, et al., 2022,
GC Insights: Space sector careers resources need a greater diversity of roles
<jats:p>Abstract. Educational research highlights that improved careers education is needed to increase participation in STEM. Current careers resources concerning the space sector, however, are found to perhaps not best reflect the diversity of roles present and may in fact perpetuate misconceptions about the usefulness of science. We, therefore, compile a more diverse set of space-related jobs, which will be used in the development of a new space careers resource.</jats:p>
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Journal articleChristensen MW, Gettelman A, Cermak J, et al., 2022,
Opportunistic experiments to constrain aerosol effective radiative forcing
, Atmospheric Chemistry and Physics, Vol: 22, Pages: 641-674, ISSN: 1680-7316Aerosol–cloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due to human activities. The nonlinearity of cloud-state changes to aerosol perturbations make it challenging to attribute causality in observed relationships of aerosol radiative forcing. Using correlations to infer causality can be challenging when meteorological variability also drives both aerosol and cloud changes independently. Natural and anthropogenic aerosol perturbations from well-defined sources provide “opportunistic experiments” (also known as natural experiments) to investigate ACI in cases where causality may be more confidently inferred. These perturbations cover a wide range of locations and spatiotemporal scales, including point sources such as volcanic eruptions or industrial sources, plumes from biomass burning or forest fires, and tracks from individual ships or shipping corridors. We review the different experimental conditions and conduct a synthesis of the available satellite datasets and field campaigns to place these opportunistic experiments on a common footing, facilitating new insights and a clearer understanding of key uncertainties in aerosol radiative forcing. Cloud albedo perturbations are strongly sensitive to background meteorological conditions. Strong liquid water path increases due to aerosol perturbations are largely ruled out by averaging across experiments. Opportunistic experiments have significantly improved process-level understanding of ACI, but it remains unclear how reliably the relationships found can be scaled to the global level, thus demonstrating a need for deeper investigation in order to improve assessments of aerosol radiative forcing and climate change.
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Journal articleChadney JM, Koskinen TT, Hu X, et al., 2022,
Energy deposition in Saturn's equatorial upper atmosphere
, Icarus, Vol: 372, Pages: 1-16, ISSN: 0019-1035We construct Saturn equatorial neutral temperature and density profiles of H, H2, He, and CH4, between 10−12 and 1 bar using measurements from Cassini’s Ion Neutral Mass Spectrometer (INMS) taken during the spacecraft’s final plunge into Saturn’s atmosphere on 15 September 2017, combined with previous deeper atmospheric measurements from the Cassini Composite InfraRed Spectrometer (CIRS) and from the UltraViolet Imaging Spectrograph (UVIS). These neutral profiles are fed into an energy deposition model employing soft X-ray and Extreme UltraViolet (EUV) solar fluxes at a range of spectral resolutions (∆λ = 4×10−3 nm to 1 nm) assembled from TIMED/SEE, from SOHO/SUMER, and from the Whole Heliosphere Interval (WHI) quiet Sun campaign. Our energy deposition model calculates ion production rate profiles through photo-ionisation and electron-impact ionisation processes, as well as rates of photo-dissociation of CH4. The ion reaction rate profiles we determine are important to obtain accurate ion density profiles, meanwhile methane photo-dissociation is key to initiate complex organic chemical processes. We assess the importance of spectral resolution in the energy deposition model by using a high-resolution H2 photo-absorption cross section, which has the effect of producing additional ionisation peaks near 800 km altitude. We find that these peaks are still formed when using low resolution (∆λ = 1 nm) or mid-resolution (∆λ = 0.1 nm) solar spectra, as long as high-resolution cross sections are included in the model.
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Journal articleStawarz J, Eastwood J, Phan T, et al., 2022,
Turbulence-driven magnetic reconnection and the magnetic correlation length: observations from magnetospheric multiscale in Earth's magnetosheath
, Physics of Plasmas, Vol: 29, Pages: 1-20, ISSN: 1070-664XTurbulent plasmas generate a multitude of thin current structures that can be sites for magnetic reconnection. The Magnetospheric Multiscale (MMS) mission has recently enabled the detailed examination of such turbulent current structures in Earth's magnetosheath and revealed that a novel type of reconnection, known as electron-only reconnection, can occur. In electron-only reconnection, ions do not have enough space to couple to the newly reconnected magnetic fields, suppressing ion jet formation and resulting in thinner sub-proton-scale current structures with faster super-Alfvénic electron jets. In this study, MMS observations are used to examine how the magnetic correlation length (λC) of the turbulence, which characterizes the size of the large-scale magnetic structures and constrains the length of the current sheets formed, influences the nature of turbulence-driven reconnection. We systematically identify 256 reconnection events across 60 intervals of magnetosheath turbulence. Most events do not appear to have ion jets; however, 18 events are identified with ion jets that are at least partially coupled to the reconnected magnetic field. The current sheet thickness and electron jet speed have a weak anti-correlation, with faster electron jets at thinner current sheets. When 𝜆𝐶≲20 ion inertial lengths, as is typical near the sub-solar magnetosheath, a tendency for thinner current sheets and potentially faster electron jets is present. The results are consistent with electron-only reconnection being more prevalent for turbulent plasmas with relatively short λC and may be relevant to the nonlinear dynamics and energy dissipation in turbulent plasmas.
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Journal articleMoestl C, Weiss AJ, Reiss MA, et al., 2022,
Multipoint Interplanetary Coronal Mass Ejections Observed with Solar Orbiter, BepiColombo, Parker Solar Probe, Wind, and STEREO-A
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 924, ISSN: 2041-8205- Cite
- Citations: 37
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Conference paperEckersley S, Rowe S, Antoniou N, et al., 2022,
A Distributed Space-Weather Sensor System using Small Satellites
, ISSN: 0074-1795Space weather is becoming increasingly important for space and terrestrial activities and is likely to transition to an operational service. Small satellites are ideally suited for space-weather measurements given the need for making simultaneous measurements across both small and large volumes of space. The “Nanosatellites for D3S” Phase 0/A study for ESA was initiated in early 2021 with the objective to assess the feasibility of using nanosatellites for future operational space weather monitoring missions in near-Earth space as part of ESA's Distributed Space Weather Sensor System (D3S) - which itself forms part of the wider ESA Enhanced Space Weather Monitoring System. The study team consortium is highly experienced including sub-contractors supporting SSTL from MSSL, Imperial College London, and VZLU. Surrey Space Centre and Northumbria University are also providing expert consultancy. In the first part of the Phase 0 study, a survey of the measurement requirements and potential space weather instruments was carried out, alongside an investigation into recent relevant nanosatellite missions and future nanosatellite technologies. This was followed by an analysis and trade-off of high level mission architecture concepts eventually converging down to two of the most promising mission architecture concepts, which were further analysed in the latter half of the Phase 0 study. The objective of the first Phase 0 mission architecture concept was to provide near-real time measurements of radiation, thermal plasma and Ionospheric neutrals/plasma, via a constellation of 20x SSTL-21 satellites, in a single LEO orbital plane. The objective of the second Phase 0 mission architecture concept was to provide near-real time measurements of radiation, the Ionosphere and the Thermosphere, via a constellation of 6x 16U SSTL-Cube satellites, in a single LEO orbital plane. The orbit selected for both missions was a 500-600km Sun-Synchronous LEO Orbit with an LTAN of 10:30a
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Journal articleVerniero JL, Chandran BDG, Larson DE, et al., 2022,
Strong Perpendicular Velocity-space Diffusion in Proton Beams Observed by Parker Solar Probe
, ASTROPHYSICAL JOURNAL, Vol: 924, ISSN: 0004-637X- Cite
- Citations: 36
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Journal articleCattell C, Breneman A, Dombeck J, et al., 2022,
Parker Solar Probe Evidence for the Absence of Whistlers Close to the Sun to Scatter Strahl and to Regulate Heat Flux
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 924, ISSN: 2041-8205- Cite
- Citations: 28
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Journal articleMalaspina DM, Stenborg G, Mehoke D, et al., 2022,
Clouds of Spacecraft Debris Liberated by Hypervelocity Dust Impacts on Parker Solar Probe
, ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X- Cite
- Citations: 16
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Journal articleLavergne A, Hemming D, Prentice IC, et al., 2022,
Global decadal variability of plant carbon isotope discrimination and its link to gross primary production.
, Global Change Biology, Vol: 28, Pages: 524-541, ISSN: 1354-1013Carbon isotope discrimination (Δ13C) in C3 woody plants is a key variable for the study of photosynthesis. Yet how Δ13C varies at decadal scales, and across regions, and how it is related to gross primary production (GPP), are still incompletely understood. Here we address these questions by implementing a new Δ13C modelling capability in the land-surface model JULES incorporating both photorespiratory and mesophyll-conductance fractionations. We test the ability of four leaf-internal CO2 concentration models embedded in JULES to reproduce leaf and tree-ring (TR) carbon isotopic data. We show that all the tested models tend to overestimate average Δ13C values, and to underestimate interannual variability in Δ13C. This is likely because they ignore the effects of soil water stress on stomatal behavior. Variations in post-photosynthetic isotopic fractionations across species, sites and years, may also partly explain the discrepancies between predicted and TR-derived Δ13C values. Nonetheless, the “least-cost” (Prentice) model shows the lowest biases with the isotopic measurements, and lead to improved predictions of canopy-level carbon and water fluxes. Overall, modelled Δ13C trends vary strongly between regions during the recent (1979–2016) historical period but stay nearly constant when averaged over the globe. Photorespiratory and mesophyll effects modulate the simulated global Δ13C trend by 0.0015 ± 0.005‰ and –0.0006 ± 0.001‰ ppm−1, respectively. These predictions contrast with previous findings based on atmospheric carbon isotope measurements. Predicted Δ13C and GPP tend to be negatively correlated in wet-humid and cold regions, and in tropical African forests, but positively related elsewhere. The negative correlation between Δ13C and GPP is partly due to the strong dominant influences of temperature on GPP and vapor pressure deficit on Δ13
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Journal articleJankee P, Oyedokun D, Soltanian M, et al., 2022,
Geomagnetically Induced Currents: Frequency Spectra and Threats to Voltage Stability
, IEEE ACCESS, Vol: 10, Pages: 62484-62501, ISSN: 2169-3536- Cite
- Citations: 6
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Conference paperAngelini V, O'Brien H, Horbury T, et al., 2022,
Novel magnetic cleaning techniques for Solar Orbiter magnetometer
, 2022 ESA Workshop on Aerospace EMC-Aerospace EMC, Publisher: IEEE -
Journal articleAdhikari S, Parashar TN, Shay MA, et al., 2021,
Energy transfer in reconnection and turbulence
, Physical Review E: Statistical, Nonlinear, and Soft Matter Physics, Vol: 104, ISSN: 1539-3755Reconnection and turbulence are two of the most commonly observed dynamical processes in plasmas, but their relationship is still not fully understood. Using 2.5D kinetic particle-in-cell simulations of both strong turbulence and reconnection, we compare the cross-scale transfer of energy in the two systems by analyzing the generalization of the von Kármán Howarth equations for Hall magnetohydrodynamics, a formulation that subsumes the third-order law for steady energy transfer rates. Even though the large scale features are quite different, the finding is that the decomposition of the energy transfer is structurally very similar in the two cases. In the reconnection case, the time evolution of the energy transfer also exhibits a correlation with the reconnection rate. These results provide explicit evidence that reconnection dynamics fundamentally involves turbulence-like energy transfer.
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Conference paperDipu S, Schwarz M, Ekman A, et al., 2021,
Exploring satellite-derived relationships between cloud droplet number concentration and liquid water path using a large-domain large-eddy simulation
<jats:p>&lt;div class=&quot;page&quot; title=&quot;Page 1&quot;&gt;&lt;div class=&quot;layoutArea&quot;&gt;&lt;div class=&quot;column&quot;&gt;&lt;p&gt;Important aspects of the adjustments to aerosol-cloud interactions can be examined using the relationship between cloud droplet number concentration (Nd) and liquid water path (LWP). Specifically, this relation can constrain the role of aerosols in leading to thicker or thinner clouds in response to adjustment mechanisms. This study investigates the satellite retrieved relationship between Nd and LWP for a selected case of mid-latitude continental clouds using high-resolution Large-eddy simulations (LES) over a large domain in weather prediction mode. Since the satellite retrieval uses adiabatic assumption to derive the Nd (NAd), we have also considered NAd from the LES model for comparison. The NAd-LWP relationship in the satellite and the LES model show similar, generally positive, but non-monotonic relations. This case over continent thus behaves differently compared to previously-published analysis of oceanic clouds, and the analysis illustrates a regime dependency (marine and continental) in the NAd-LWP relation in the satellite retrievals. The study further explores the impact of the satellite&amp;#160;retrieval assumptions on the Nd-LWP relationship. When considering the relationship of the actually simulated cloud-top Nd, rather than NAd, with LWP, the result shows a much more nonlinear relationship. The difference is much less pronounced, however, for shallow stratiform than for convective clouds. Comparing local vs large-scale statistics from satellite data shows that continental clouds exhibit only a weak nonlinear Nd-LWP relationship. Hence a regime based Nd-LWP analysis is even more relevant when it comes to continental clouds.&lt;/p&gt;&lt;
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Journal articleAdhikari L, Zank GP, Zhao L-L, et al., 2021,
Evolution of anisotropic turbulence in the fast and slow solar wind: Theory and Solar Orbiter measurements
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Cite
- Citations: 11
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Journal articlevon Forstner JLF, Dumbovi M, Moestl C, et al., 2021,
Radial evolution of the April 2020 stealth coronal mass ejection between 0.8 and 1AU Comparison of Forbush decreases at Solar Orbiter and near the Earth
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Cite
- Citations: 13
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Journal articleZhao L-L, Zank GP, He JS, et al., 2021,
Turbulence and wave transmission at an ICME-driven shock observed by the Solar Orbiter and Wind
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Cite
- Citations: 32
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Journal articleDavies EE, Mostl C, Owens MJ, et al., 2021,
In situ multi-spacecraft and remote imaging observations of the first CME detected by Solar Orbiter and BepiColombo
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Cite
- Citations: 22
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Journal articleVerscharen D, Stansby D, Finley AJ, et al., 2021,
The angular-momentum flux in the solar wind observed during Solar Orbiter's first orbit
, Astronomy and Astrophysics: a European journal, Vol: 656, Pages: 1-10, ISSN: 0004-6361Aims. We present the first measurements of the angular-momentum flux in the solar wind recorded by the Solar Orbiter spacecraft. Our aim is to validate these measurements to support future studies of the Sun’s angular-momentum loss.Methods. We combined 60-min averages of the proton bulk moments and the magnetic field measured by the Solar Wind Analyser and the magnetometer onboard Solar Orbiter. We calculated the angular-momentum flux per solid-angle element using data from the first orbit of the mission’s cruise phase in 2020. We separated the contributions from protons and from magnetic stresses to the total angular-momentum flux.Results. The angular-momentum flux varies significantly over time. The particle contribution typically dominates over the magnetic-field contribution during our measurement interval. The total angular-momentum flux shows the largest variation and is typically anti-correlated with the radial solar-wind speed. We identify a compression region, potentially associated with a co-rotating interaction region or a coronal mass ejection, which leads to a significant localised increase in the angular-momentum flux, albeit without a significant increase in the angular momentum per unit mass. We repeated our analysis using the density estimate from the Radio and Plasma Waves instrument. Using this independent method, we find a decrease in the peaks of positive angular-momentum flux, but otherwise, our results remain consistent.Conclusions. Our results largely agree with previous measurements of the solar wind’s angular-momentum flux in terms of amplitude, variability, and dependence on radial solar-wind bulk speed. Our analysis highlights the potential for more detailed future studies of the solar wind’s angular momentum and its other large-scale properties with data from Solar Orbiter. We emphasise the need for studying the radial evolution and latitudinal dependence of the angular-momentum flux in combination with data from
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Journal articleCarbone F, Sorriso-Valvo L, Khotyaintsev Y, et al., 2021,
Statistical study of electron density turbulence and ion-cyclotron waves in the inner heliosphere: Solar Orbiter observations
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Cite
- Citations: 1
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Journal articlePisa D, Santolik O, Hanzelka M, et al., 2021,
First-year ion-acoustic wave observations in the solar wind by the RPW/TDS instrument on board Solar Orbiter
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Cite
- Citations: 8
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Journal articleSteinvall K, Khotyaintsev Y, Cozzani G, et al., 2021,
Solar wind current sheets and deHoffmann-Teller analysis First results from Solar Orbiter's DC electric field measurements
, Astronomy and Astrophysics: a European journal, Vol: 656, Pages: 1-7, ISSN: 0004-6361Context. Solar Orbiter was launched on 10 February 2020 with the purpose of investigating solar and heliospheric physics using a payload of instruments designed for both remote and in situ studies. Similar to the recently launched Parker Solar Probe, and unlike earlier missions, Solar Orbiter carries instruments designed to measure low-frequency DC electric fields.Aims. In this paper, we assess the quality of the low-frequency DC electric field measured by the Radio and Plasma Waves instrument (RPW) on Solar Orbiter. In particular, we investigate the possibility of using Solar Orbiter’s DC electric and magnetic field data to estimate the solar wind speed.Methods. We used a deHoffmann-Teller (HT) analysis, based on measurements of the electric and magnetic fields, to find the velocity of solar wind current sheets, which minimises a single component of the electric field. By comparing the HT velocity to the proton velocity measured by the Proton and Alpha particle Sensor (PAS), we have developed a simple model for the effective antenna length, Leff of the E-field probes. We then used the HT method to estimate the speed of the solar wind.Results. Using the HT method, we find that the observed variations in Ey are often in excellent agreement with the variations in the magnetic field. The magnitude of Ey, however, is uncertain due to the fact that the Leff depends on the plasma environment. Here, we derive an empirical model relating Leff to the Debye length, which we can use to improve the estimate of Ey and, consequently, the estimated solar wind speed.Conclusions. The low-frequency electric field provided by RPW is of high quality. Using the deHoffmann-Teller analysis, Solar Orbiter’s magnetic and electric field measurements can be used to estimate the solar wind speed when plasma data are unavailable.
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Journal articleGraham DB, Khotyaintsev Y, Vaivads A, et al., 2021,
Kinetic electrostatic waves and their association with current structures in the solar wind
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Cite
- Citations: 7
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Journal articleKhotyaintsev Y, Graham DB, Vaivads A, et al., 2021,
Density fluctuations associated with turbulence and waves First observations by Solar Orbiter
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Cite
- Citations: 15
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Journal articleWeiss AJ, Moestl C, Davies EE, et al., 2021,
Multi-point analysis of coronal mass ejection flux ropes using combined data from Solar Orbiter, BepiColombo, and Wind
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Cite
- Citations: 9
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Journal articleKretzschmar M, Chust T, Krasnoselskikh V, et al., 2021,
Whistler waves observed by Solar Orbiter/RPW between 0.5 AU and 1 AU
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Cite
- Citations: 11
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Journal articleEastwood JP, Stawarz JE, Phan TD, et al., 2021,
Solar Orbiter observations of an ion-scale flux rope confined to a bifurcated solar wind current sheet
, Astronomy & Astrophysics, Vol: 656, Pages: 1-8, ISSN: 0004-6361Context. Flux ropes in the solar wind are a key element of heliospheric dynamics and particle acceleration. When associated withcurrent sheets, the primary formation mechanism is magnetic reconnection and flux ropes in current sheets are commonly used astracers of the reconnection process.Aims. Whilst flux ropes associated with reconnecting current sheets in the solar wind have been reported, their occurrence, sizedistribution, and lifetime are not well understood.Methods. Here we present and analyse new Solar Orbiter magnetic field data reporting novel observations of a flux rope confined toa bifurcated current sheet in the solar wind. Comparative data and large-scale context is provided by Wind.Results. The Solar Orbiter observations reveal that the flux rope, which does not span the current sheet, is of ion scale, and in areconnection formation scenario, existed for a prolonged period of time as it was carried out in the reconnection exhaust. Wind is alsofound to have observed clear signatures of reconnection at what may be the same current sheet, thus demonstrating that reconnectionsignatures can be found separated by as much as ∼ 2 000 Earth radii, or 0.08 au.Conclusions. The Solar Orbiter observations provide new insight into the hierarchy of scales on which flux ropes can form, and showthat they exist down to the ion scale in the solar wind. The context provided by Wind extends the spatial scale over which reconnectionsignatures have been found at solar wind current sheets. The data suggest the local orientations of the current sheet at Solar Orbiterand Wind are rotated relative to each other, unlike reconnection observed at smaller separations; the implications of this are discussedwith reference to patchy vs. continuous reconnection scenarios.
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Journal articleLavraud B, Kieokaew R, Fargette N, et al., 2021,
Magnetic reconnection as a mechanism to produce multiple protonpopulations and beams locally in the solar wind
, Journal of Astrophysics and Astronomy, Vol: 656, Pages: 1-8, ISSN: 0250-6335Context. Spacecraft observations early revealed frequent multiple protonpopulations in the solar wind. Decades of research on their origin have focusedon processes such as magnetic reconnection in the low corona and wave-particleinteractions in the corona and locally in the solar wind.Aims.This study aimsto highlight that multiple proton populations and beams are also produced bymagnetic reconnection occurring locally in the solar wind. Methods. We use highresolution Solar Orbiter proton velocity distribution function measurements,complemented by electron and magnetic field data, to analyze the association ofmultiple proton populations and beams with magnetic reconnection during aperiod of slow Alfv\'enic solar wind on 16 July 2020. Results. At least 6reconnecting current sheets with associated multiple proton populations andbeams, including a case of magnetic reconnection at a switchback boundary, arefound during this day. This represents 2% of the measured distributionfunctions. We discuss how this proportion may be underestimated, and how it maydepend on solar wind type and distance from the Sun. Conclusions. Althoughsuggesting a likely small contribution, but which remains to be quantitativelyassessed, Solar Orbiter observations show that magnetic reconnection must beconsidered as one of the mechanisms that produce multiple proton populationsand beams locally in the solar wind.
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Journal articleWimmer-Schweingruber RF, Janitzek NP, Pacheco D, et al., 2021,
First year of energetic particle measurements in the inner heliosphere with Solar Orbiter's Energetic Particle Detector
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Cite
- Citations: 53
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Journal articleCohen CMS, Christian ER, Cummings AC, et al., 2021,
PSP/IS⊙IS observations of the 29 November 2020 solar energetic particle event
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Cite
- Citations: 22
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