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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- Author Web Link
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- Citations: 18
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Journal articleBlasl KA, Nakamura TKM, Plaschke F, et al., 2022,
Multi-scale observations of the magnetopause Kelvin-Helmholtz waves during southward IMF
, PHYSICS OF PLASMAS, Vol: 29, ISSN: 1070-664X- Author Web Link
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- Citations: 9
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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 articleNakamura TKM, Blasl KA, Hasegawa H, et al., 2022,
Multi-scale evolution of Kelvin–Helmholtz waves at the earth's magnetopause during southward IMF periods
, Physics of Plasmas, Vol: 29, Pages: 012901-012901, ISSN: 1070-664XAt the Earth's low-latitude magnetopause, the Kelvin–Helmholtz instability (KHI), driven by the velocity shear between the magnetosheath and magnetosphere, has been frequently observed during northward interplanetary magnetic field (IMF) periods. However, the signatures of the KHI have been much less frequently observed during southward IMF periods, and how the KHI develops under southward IMF has been less explored. Here, we performed a series of realistic 2D and 3D fully kinetic simulations of a KH wave event observed by the Magnetospheric Multiscale (MMS) mission at the dusk-flank magnetopause during southward IMF on September 23, 2017. The simulations demonstrate that the primary KHI bends the magnetopause current layer and excites the Rayleigh–Taylor instability (RTI), leading to penetration of high-density arms into the magnetospheric side. This arm penetration disturbs the structures of the vortex layer and produces intermittent and irregular variations of the surface waves which significantly reduces the observational probability of the periodic KH waves. The simulations further demonstrate that in the non-linear growth phase of the primary KHI, the lower-hybrid drift instability (LHDI) is induced near the edge of the primary vortices and contributes to an efficient plasma mixing across the magnetopause. The signatures of the large-scale surface waves by the KHI/RTI and the small-scale fluctuations by the LHDI are reasonably consistent with the MMS observations. These results indicate that the multi-scale evolution of the magnetopause KH waves and the resulting plasma transport and mixing as seen in the simulations may occur during southward IMF
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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- Author Web Link
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- Citations: 1
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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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Journal articleWright CJ, Hall RJ, Banyard TP, et al., 2021,
Dynamical and surface impacts of the January 2021 sudden stratospheric warming in novel Aeolus wind observations, MLS and ERA5
, WEATHER AND CLIMATE DYNAMICS, Vol: 2, Pages: 1283-1301 -
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 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- Author Web Link
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- Citations: 11
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Journal articleZaslavsky A, Mann I, Soucek J, et al., 2021,
First dust measurements with the Solar Orbiter Radio and Plasma Wave instrument
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Author Web Link
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- Citations: 8
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Journal articleAllen RC, Cernuda I, Pacheco D, et al., 2021,
Energetic ions in the Venusian system: Insights from the first Solar Orbiter flyby
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Author Web Link
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- Citations: 7
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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- Author Web Link
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- Citations: 10
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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- Author Web Link
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- 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- Author Web Link
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- 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- Author Web Link
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- 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- Author Web Link
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- 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- Author Web Link
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- 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- Author Web Link
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- Citations: 9
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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- Author Web Link
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- Citations: 21
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Journal articleKasper JC, Klein KG, Lichko E, et al., 2021,
<i>Parker</i><i> Solar</i><i> Probe</i> Enters the Magnetically Dominated Solar Corona
, PHYSICAL REVIEW LETTERS, Vol: 127, ISSN: 0031-9007- Author Web Link
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- Citations: 64
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Journal articleVecchio A, Maksimovic M, Krupar V, et al., 2021,
Solar Orbiter/RPW antenna calibration in the radio domain and its application to type III burst observations
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Author Web Link
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- Citations: 3
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Journal articleMusset S, Maksimovic M, Kontar E, et al., 2021,
Simulations of radio-wave anisotropic scattering to interpret type III radio burst data from Solar Orbiter, Parker Solar Probe, STEREO, and Wind
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Author Web Link
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- Citations: 7
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Journal articleSoucek J, Pisa D, Kolmasova I, et al., 2021,
Solar Orbiter Radio and Plasma Waves - Time Domain Sampler: In-flight performance and first results
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Author Web Link
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- Citations: 6
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Journal articleGomez-Herrero R, Pacheco D, Kollhoff A, et al., 2021,
First near-relativistic solar electron events observed by EPD onboard Solar Orbiter
, ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361- Author Web Link
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- Citations: 13
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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- Author Web Link
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- Citations: 11
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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- Author Web Link
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- Citations: 11
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