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  • Journal article
    Kollhoff A, Kouloumvakos A, Lario D, Dresing N, Gomez-Herrero R, Rodriguez-Garcia L, Malandraki OE, Richardson IG, Posner A, Klein K-L, Pacheco D, Klassen A, Heber B, Cohen CMS, Laitinen T, Cernuda I, Dalla S, Lara FE, Vainio R, Koeberle M, Kuehl R, Xu ZG, Berger L, Eldrum S, Bruedern M, Laurenza M, Kilpua EJ, Aran A, Rouillard AP, Bucik R, Wijsen N, Pomoell J, Wimmer-Schweingruber RF, Martin C, Boettcher S, von Forstner JLF, Terasa J-C, Boden S, Kulkarni SR, Ravanbakhsh A, Yedla M, Janitzek N, Rodriguez-Pacheco J, Mateo MP, Prieto SS, Espada PP, Polo OR, Hellin AM, Carcaboso F, Mason GM, Ho GC, Allen RC, Andrews GB, Schlemm CE, Seifert H, Tyagi K, Lees WJ, Hayes J, Bale SD, Krupar V, Horbury TS, Angelini V, Evans V, O'Brien H, Maksimovic M, Khotyaintsev Y, Vecchio A, Steinvall K, Asvestari Eet al., 2021,

    The first widespread solar energetic particle event observed by Solar Orbiter on 2020 November 29

    , ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361
  • Journal article
    D'Amicis R, Bruno R, Panasenco O, Telloni D, Perrone D, Marcucci MF, Woodham L, Velli M, De Marco R, Jagarlamudi V, Coco I, Owen C, Louarn P, Livi S, Horbury T, Andre N, Angelini V, Evans V, Fedorov A, Genot V, Lavraud B, Matteini L, Muller D, O'Brien H, Pezzi O, Rouillard AP, Sorriso-Valvo L, Tenerani A, Verscharen D, Zouganelis Iet al., 2021,

    First Solar Orbiter observation of the Alfvenic slow wind and identification of its solar source

    , Astronomy and Astrophysics: a European journal, Vol: 656, Pages: 1-17, ISSN: 0004-6361

    Context. Turbulence dominated by large-amplitude, nonlinear Alfvén-like fluctuations mainly propagating away from the Sun is ubiquitous in high-speed solar wind streams. Recent studies have demontrated that slow wind streams may also show strong Alfvénic signatures, especially in the inner heliosphere.Aims. The present study focuses on the characterisation of an Alfvénic slow solar wind interval observed by Solar Orbiter between 14 and 18 July 2020 at a heliocentric distance of 0.64 AU.Methods. Our analysis is based on plasma moments and magnetic field measurements from the Solar Wind Analyser (SWA) and Magnetometer (MAG) instruments, respectively. We compared the behaviour of different parameters to characterise the stream in terms of the Alfvénic content and magnetic properties. We also performed a spectral analysis to highlight spectral features and waves signature using power spectral density and magnetic helicity spectrograms, respectively. Moreover, we reconstruct the Solar Orbiter magnetic connectivity to the solar sources both via a ballistic and a potential field source surface (PFSS) model.Results. The Alfvénic slow wind stream described in this paper resembles, in many respects, a fast wind stream. Indeed, at large scales, the time series of the speed profile shows a compression region, a main portion of the stream, and a rarefaction region, characterised by different features. Moreover, before the rarefaction region, we pinpoint several structures at different scales recalling the spaghetti-like flux-tube texture of the interplanetary magnetic field. Finally, we identify the connections between Solar Orbiter in situ measurements, tracing them down to coronal streamer and pseudostreamer configurations.Conclusions. The characterisation of the Alfvénic slow wind stream observed by Solar Orbiter and the identification of its solar source are extremely important aspects for improving the understanding of future observ
  • Journal article
    Allen RC, Cernuda I, Pacheco D, Berger L, Xu ZG, von Forstner JLF, Rodriguez-Pacheco J, Wimmer-Schweingruber RF, Ho GC, Mason GM, Vines SK, Khotyaintsev Y, Horbury T, Maksimovic M, Hadid LZ, Volwerk M, Dimmock AP, Sorriso-Valvo L, Stergiopoulou K, Andrews GB, Angelini V, Bale SD, Boden S, Boettcher S, Chust T, Eldrum S, Espada PP, Lara FE, Evans V, Gomez-Herrero R, Hayes JR, Hellin AM, Kollhoff A, Krasnoselskikh V, Kretzschmar M, Kuehl P, Kulkarni SR, Lees WJ, Lorfevre E, Martin C, O'Brien H, Plettemeier D, Polo OR, Prieto M, Ravanbakhsh A, Sanchez-Prieto S, Schlemm CE, Seifert H, Soucek J, Steller M, Stverak S, Terasa JC, Travnicek P, Tyagi K, Vaivads A, Vecchio A, Yedla Met al., 2021,

    Energetic ions in the Venusian system: Insights from the first Solar Orbiter flyby

    , ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361
  • Journal article
    von Forstner JLF, Dumbovi M, Moestl C, Guo J, Papaioannou A, Elftmann R, Xu Z, Terasa JC, Kollhoff A, Wimmer-Schweingruber RF, Rodriguez-Pacheco J, Weiss AJ, Hinterreiter J, Amerstorfer T, Bauer M, Belov A, Abunina MA, Horbury T, Davies EE, O'Brien H, Allen RC, Andrews GB, Berger L, Boden S, Cernuda Cangas I, Eldrum S, Espinosa Lara F, Gomez Herrero R, Hayes JR, Ho GC, Kulkarni SR, Lees WJ, Martin C, Mason GM, Pacheco D, Prieto Mateo M, Ravanbakhsh A, Rodriguez Polo O, Sanchez Prieto S, Schlemm CE, Seifert H, Tyagi K, Yedla Met 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
  • Journal article
    Fedorov A, Louarn P, Owen CJ, Horbury TS, Prech L, Durovcova T, Barthe A, Rouillard AP, Kasper JC, Bale SD, Bruno R, O'Brien H, Evans V, Angelini V, Larson D, Livi R, Lavraud B, Andre N, Genot V, Penou E, Mele G, Fortunato Vet al., 2021,

    Switchback-like structures observed by Solar Orbiter

    , ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361
  • Journal article
    Chust T, Kretzschmar M, Graham DB, Le Contel O, Retino A, Alexandrova A, Berthomier M, Hadid LZ, Sahraoui F, Jeandet A, Leroy P, Pellion J-C, Bouzid V, Katra B, Piberne R, Khotyaintsev Y, Vaivads A, Krasnoselskikh V, Soucek J, Santolik O, Lorfevre E, Plettemeier D, Steller M, Stverak S, Vecchio A, Maksimovic M, Bale SD, Horbury TS, O'Brien H, Evans V, Angelini Vet al., 2021,

    Observations of whistler mode waves by Solar Orbiter's RPW Low Frequency Receiver (LFR): In-flight performance and first results

    , ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361
  • Journal article
    Aran A, Pacheco D, Laurenza M, Wijsen N, Lario D, Benella S, Richardson IG, Samara E, von Forstner JLF, Sanahuja B, Rodriguez L, Balmaceda L, Lara FE, Gomez-Herrero R, Steinvall K, Vecchio A, Krupar V, Poedts S, Allen RC, Andrews GB, Angelini V, Berger L, Berghmans D, Boden S, Bottcher S, Carcaboso F, Cernuda I, De Marco R, Eldrum S, Evans V, Fedorov A, Hayes J, Ho GC, Horbury TS, Janitzek NP, Khotyaintsev Y, Kollhoff A, Kuehl P, Kulkarni SR, Lees WJ, Louarn P, Magdalenic J, Maksimovic M, Malandraki O, Martinez A, Mason GM, Martin C, O'Brien H, Owen C, Parra P, Prieto Mateo M, Ravanbakhsh A, Rodriguez-Pacheco J, Rodriguez Polo O, Sanchez Prieto S, Schlemm CE, Seifert H, Terasa JC, Tyagi K, Verbeeck C, Wimmer-Schweingruber RF, Xu ZG, Yedla MK, Zhukov ANet al., 2021,

    Evidence for local particle acceleration in the first recurrent galactic cosmic ray depression observed by Solar Orbiter The ion event on 19 June 2020

    , ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361
  • Journal article
    Louarn P, Fedorov A, Prech L, Owen CJ, Bruno R, Livi S, Lavraud B, Rouillard AP, Genot V, Andre N, Fruit G, Reville V, Kieokaew R, Plotnikov I, Penou E, Barthe A, Khataria D, Berthomier M, D'Amicis R, Sorriso-Valvo L, Allegrini F, Raines J, Verscharen D, Fortunato V, Mele G, Horbury TS, O'brien H, Evans V, Angelini V, Maksimovic M, Kasper JC, Bale SDet al., 2021,

    Multiscale views of an Alfvenic slow solar wind: 3D velocity distribution functions observed by the Proton-Alpha Sensor of Solar Orbiter

    , ASTRONOMY & ASTROPHYSICS, Vol: 656, ISSN: 0004-6361
  • Journal article
    Cargill PJ, Bradshaw SJ, Klimchuk JA, Barnes WTet al., 2021,

    Static and dynamic solar coronal loops with cross-sectional area variations

    , Monthly Notices of the Royal Astronomical Society, Vol: 509, Pages: 4420-4429, ISSN: 0035-8711

    The Enthalpy Based Thermal Evolution of Loops approximate model for static and dynamic coronal loops is developed to include the effect of a loop cross-sectional area which increases from the base of the transition region (TR) to the corona. The TR is defined as the part of a loop between the top of the chromosphere and the location where thermal conduction changes from an energy loss to an energy gain. There are significant differences from constant area loops due to the manner in which the reduced volume of the TR responds to conductive and enthalpy fluxes from the corona. For static loops with modest area variation the standard picture of loop energy balance is retained, with the corona and TR being primarily a balance between heating and conductive losses in the corona, and downward conduction and radiation to space in the TR. As the area at the loop apex increases, the TR becomes thicker and the density in TR and corona larger. For large apex areas, the coronal energy balance changes to one primarily between heating and radiation, with conduction playing an increasingly unimportant role, and the TR thickness becoming a significant fraction of the loop length. Approximate scaling laws are derived that give agreement with full numerical solutions for the density, but not the temperature. For non-uniform areas, dynamic loops have a higher peak temperature and are denser in the radiative cooling phase by of order 50 per cent than the constant area case for the examples considered. They also show a final rapid cooling and draining once the temperature approaches 1 MK. Although the magnitude of the emission measure will be enhanced in the radiative phase, there is little change in the important observational diagnostic of its temperature dependence.
  • Journal article
    Schwartz S, Kucharek H, Farrugia C, Trattner K, Gingell I, Chasapis A, Gershman D, Strangeway Ret al., 2021,

    Characteristics of Intense Current-carrying Structures in the Terrestrial Magnetosheath
  • Journal article
    Volwerk M, Horbury TS, Woodham LD, Bale SD, Simon Wedlund C, Schmid D, Allen RC, Angelini V, Baumjohann W, Berger L, Edberg NJT, Evans V, Hadid LZ, Ho GC, Khotyaintsev YV, Magnes W, Maksimovic M, OBrien H, Steller MB, Rodriguez-Pacheco J, Wimmer-Scheingruber RFet al., 2021,

    Solar Orbiter’s first Venus flyby. MAG observations of structures and waves associated with the induced Venusian magnetosphere

    , Astronomy and Astrophysics: a European journal, Vol: 656, ISSN: 0004-6361

    Context. The induced magnetosphere of Venus is caused by the interaction of the solar wind and embedded interplanetary magnetic field with the exosphere and ionosphere of Venus. Solar Orbiter entered Venus’s magnetotail far downstream, > 70 Venus radii, of the planet and exited the magnetosphere over the north pole. This offered a unique view of the system over distances that had only been flown through before by three other missions, Mariner 10, Galileo, and BepiColombo.Aims. In this study, we study the large-scale structure and activity of the induced magnetosphere as well as the high-frequency plasma waves both in the magnetosphere and in a limited region upstream of the planet where interaction with Venus’s exosphere is expected.Methods. The large-scale structure of the magnetosphere was studied with low-pass filtered data and identified events are investigated with a minimum variance analysis as well as combined with plasma data. The high-frequency plasma waves were studied with spectral analysis.Results. We find that Venus’s magnetotail is very active during the Solar Orbiter flyby. Structures such as flux ropes and reconnection sites were encountered, in addition to a strong overdraping of the magnetic field downstream of the bow shock and planet. High-frequency plasma waves (up to six times the local proton cyclotron frequency) are observed in the magnetotail, which are identified as Doppler-shifted proton cyclotron waves, whereas in the upstream solar wind, these waves appear just below the proton cyclotron frequency (as expected) but are very patchy. The bow shock is quasi-perpendicular, however, expected mirror mode activity is not found directly behind it; instead, there is strong cyclotron wave power. This is most likely caused by the relatively low plasma-β behind the bow shock. Much further downstream, magnetic hole or mirror mode structures are identified in the magnetosheath.
  • Journal article
    Kieokaew R, Lavraud B, Yang Y, Matthaeus WH, Ruffolo D, Stawarz JE, Aizawa S, Foullon C, Génot V, Pinto RF, Fargette N, Louarn P, Rouillard A, Fedorov A, Penou E, Owen CJ, Horbury T, O'Brien H, Evans V, Angelini Vet al., 2021,

    Solar Orbiter observations of the Kelvin-Helmholtz waves in the solar wind

    , Astronomy and Astrophysics: a European journal, Vol: 656, ISSN: 0004-6361

    Context. The Kelvin-HeImholtz (KH) instability is a nonlinear shear-driven instability that develops at the interface between shear flows in plasmas. KH waves have been inferred in various astrophysical plasmas, and have been observed in situ at the magnetospheric boundaries of solar-system planets and through remote sensing at the boundaries of coronal mass ejections.Aims. KH waves are also expected to develop at flow shear interfaces in the solar wind. While they were hypothesized to play an important role in the mixing of plasmas and in triggering solar wind fluctuations, their direct and unambiguous observation in the solar wind was still lacking.Methods. We report in situ observations of quasi-periodic magnetic and velocity field variations plausibly associated with KH waves using Solar Orbiter during its cruise phase. They are found in a shear layer in the slow solar wind in the close vicinity of the heliospheric current sheet. An analysis was performed to derive the local configuration of the waves. A 2D magnetohydrodynamics simulation was also set up with approximate empirical values to test the stability of the shear layer. In addition, magnetic spectra of the event were analyzed.Results. We find that the observed conditions satisfy the KH instability onset criterion from the linear theory analysis, and its development is further confirmed by the simulation. The current sheet geometry analyses are found to be consistent with KH wave development, albeit with some limitations likely owing to the complex 3D nature of the event and solar wind propagation. Additionally, we report observations of an ion jet consistent with magnetic reconnection at a compressed current sheet within the KH wave interval. The KH activity is found to excite magnetic and velocity fluctuations with power law scalings that approximately follow k−5/3 and k−2.8 in the inertial and dissipation ranges, respectively. Finally, we discuss reasons for the lack of in situ KH wave det
  • Journal article
    Bale SD, Horbury TS, Velli M, Desai MI, Halekas JS, McManus MD, Panasenco O, Badman ST, Bowen TA, Chandran BDG, Drake JF, Kasper JC, Laker R, Mallet A, Matteini L, Phan TD, Raouafi NE, Squire J, Woodham LD, Woolley Tet al., 2021,

    A solar source of alfvenic magnetic field switchbacks: in situ remnants of magnetic funnels on supergranulation scales

    , The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 923, Pages: 1-12, ISSN: 0004-637X

    One of the striking observations from the Parker Solar Probe (PSP) spacecraft is the prevalence in the inner heliosphere of large amplitude, Alfvénic magnetic field reversals termed switchbacks. These $\delta {B}_{R}/B\sim { \mathcal O }(1$) fluctuations occur over a range of timescales and in patches separated by intervals of quiet, radial magnetic field. We use measurements from PSP to demonstrate that patches of switchbacks are localized within the extensions of plasma structures originating at the base of the corona. These structures are characterized by an increase in alpha particle abundance, Mach number, plasma β and pressure, and by depletions in the magnetic field magnitude and electron temperature. These intervals are in pressure balance, implying stationary spatial structure, and the field depressions are consistent with overexpanded flux tubes. The structures are asymmetric in Carrington longitude with a steeper leading edge and a small (∼1°) edge of hotter plasma and enhanced magnetic field fluctuations. Some structures contain suprathermal ions to ∼85 keV that we argue are the energetic tail of the solar wind alpha population. The structures are separated in longitude by angular scales associated with supergranulation. This suggests that these switchbacks originate near the leading edge of the diverging magnetic field funnels associated with the network magnetic field—the primary wind sources. We propose an origin of the magnetic field switchbacks, hot plasma and suprathermals, alpha particles in interchange reconnection events just above the solar transition region and our measurements represent the extended regions of a turbulent outflow exhaust.
  • Journal article
    Cochrane CJ, Vance SD, Nordheim TA, Styczinski M, Masters A, Regoli LHet al., 2021,

    In search of subsurface oceans within the Uranian moons

    , Journal of Geophysical Research: Planets, Vol: 126, ISSN: 2169-9097

    The Galileo mission to Jupiter discovered magnetic signatures associated with hidden sub-surface oceans at the moons Europa and Callisto using the phenomenon of magnetic induction. These induced magnetic fields originate from electrically conductive layers within the moons and are driven by Jupiter’s strong time-varying magnetic field. The ice giants and their moons are also ideal laboratories for magnetic induction studies. Both Uranus and Neptune have a strongly tilted magnetic axis with respect to their spin axis, creating a dynamic and strongly variable magnetic field environment at the orbits of their major moons. Although Voyager-2 visited the ice giants in the 1980s, it did not pass close enough to any of the moons to detect magnetic induction signatures. However, Voyager-2 revealed that some of these moons exhibit surface features that hint at recent geologically activity, possibly associated with sub-surface oceans. Future missions to the ice giants may therefore be capable of discovering sub-surface oceans, thereby adding to the family of known “ocean worlds” in our solar system. Here, we assess magnetic induction as a technique for investigating sub-surface oceans within the major moons of Uranus. Furthermore, we establish the ability to distinguish induction responses created by different interior characteristics that tie into the induction response: ocean thickness, conductivity, and depth, and ionospheric conductance. The results reported here demonstrate the possibility of single-pass ocean detection and constrained characterization within the moons of Miranda, Ariel, and Umbriel, and provide guidance for magnetometer selection and trajectory design for future missions to Uranus.
  • Journal article
    Oieroset M, Phan TD, Ergun R, Ahmadi N, Genestreti K, Drake JF, Liu Y-H, Haggerty C, Eastwood JP, Shay MA, Pyakurel PS, Haaland S, Oka M, Goodbred M, Eriksson S, Burch JL, Torbert RB, Khotyaintsev Y, Russell CT, Strangeway RJ, Gershman DJ, Giles BLet al., 2021,

    Spatial evolution of magnetic reconnection diffusion region structures with distance from the X-line

    , Physics of Plasmas, Vol: 28, ISSN: 1070-664X

    We report Magnetospheric Multiscale four-spacecraft observations of a thin reconnecting current sheet with weakly asymmetric inflow conditions and a guide field of approximately twice the reconnecting magnetic field. The event was observed at the interface of interlinked magnetic field lines at the flank magnetopause when the maximum spacecraft separation was 370 km and the spacecraft covered ∼1.7 ion inertial lengths (di) in the reconnection outflow direction. The ion-scale spacecraft separation made it possible to observe the transition from electron-only super ion-Alfvénic outflow near the electron diffusion region (EDR) to the emergence of sub-Alfvénic ion outflow in the ion diffusion region (IDR). The EDR to IDR evolution over a distance less than 2 di also shows the transition from a near-linear reconnecting magnetic field reversal to a more bifurcated current sheet as well as significant decreases in the parallel electric field and dissipation. Both the ion and electron heating in this diffusion region event were similar to the previously reported heating in the far downstream exhausts. The dimensionless reconnection rate, obtained four different ways, was in the range of 0.13–0.27. This event reveals the rapid spatial evolution of the plasma and electromagnetic fields through the EDR to IDR transition region
  • Journal article
    Cheng ZW, Shi JK, Torkar K, Lu GP, Dunlop MW, Carr CM, Reme H, Dandouras I, Fazakerley Aet al., 2021,

    Impact of the solar wind dynamic pressure on the field-aligned currents in the magnetotail: cluster observation

    , JGR: Space Physics, Vol: 126, Pages: 1-12, ISSN: 2169-9402

    We statistically investigate the influence of the solar wind dynamic pressure (SW Pdyn) on the field-aligned currents (FACs) in the magnetotail with 1,492 FAC cases from July to October in 2001 and 2004, which covers 74 Cluster crossings of the plasma sheet boundary layer (PSBL) in both storm time and non-storm time. The FAC density in the magnetotail is derived from the magnetic field data with the four-point measurement of Cluster, and the SW Pdyn is taken from ACE data. The results indicate the FAC density becomes stronger with increasing SW Pdyn. The statistics show that the FAC occurrence increased monotonically with SW Pdyn in the three levels (Weak: SW Pdyn < 2 nPa; Medium: 2 nPa ≤ SW Pdyn ≤ 5 nPa; Strong: SW Pdyn > 5 nPa). The FAC density increased with increasing SW Pdyn, while its footprint (invariant latitude, ILAT) in the polar region decreased with increasing SW Pdyn. The response of the FAC to SW Pdyn in the magnetotail had a north-south hemispheric asymmetry. The FAC density had a better correlation with SW Pdyn in the Northern hemisphere, while the footprint had a better correlation with SW Pdyn in the Southern hemisphere. Possible underlying mechanisms for our results are analyzed and discussed. However, it requires more observations and simulation studies to find out the mechanism of north-south asymmetry.
  • Journal article
    Matteini L, Laker R, Horbury T, Woodham L, Bale SD, Stawarz JE, Woolley T, Steinvall K, Jones GH, Grant SR, Afghan Q, Galand M, O'Brien H, Evans V, Angelini V, Maksimovic M, Chust T, Khotyaintsev Y, Krasnoselskikh V, Kretzschmar M, Lorfevre E, Plettemeier D, Soucek J, Steller M, Stverak S, Travnicek P, Vaivads A, Vecchio A, Wimmer-Schweingruber RF, Ho GC, Gomez-Herrero R, Rodriguez-Pacheco J, Louarn P, Fedorov A, Owen CJ, Bruno R, Livi S, Zouganelis I, Muller Det al., 2021,

    Solar Orbiter's encounter with the tail of comet C/2019 Y4 (ATLAS): Magnetic field draping and cometary pick-up ion waves

    , Astronomy and Astrophysics: a European journal, Vol: 656, ISSN: 0004-6361

    ontext. Solar Orbiter is expected to have flown close to the tail of comet C/2019 Y4 (ATLAS) during the spacecraft’s first perihelion in June 2020. Models predict a possible crossing of the comet tails by the spacecraft at a distance from the Sun of approximately 0.5 AU.Aims. This study is aimed at identifying possible signatures of the interaction of the solar wind plasma with material released by comet ATLAS, including the detection of draped magnetic field as well as the presence of cometary pick-up ions and of ion-scale waves excited by associated instabilities. This encounter provides us with the first opportunity of addressing such dynamics in the inner Heliosphere and improving our understanding of the plasma interaction between comets and the solar wind.Methods. We analysed data from all in situ instruments on board Solar Orbiter and compared their independent measurements in order to identify and characterize the nature of structures and waves observed in the plasma when the encounter was predicted.Results. We identified a magnetic field structure observed at the start of 4 June, associated with a full magnetic reversal, a local deceleration of the flow and large plasma density, and enhanced dust and energetic ions events. The cross-comparison of all these observations support a possible cometary origin for this structure and suggests the presence of magnetic field draping around some low-field and high-density object. Inside and around this large scale structure, several ion-scale wave-forms are detected that are consistent with small-scale waves and structures generated by cometary pick-up ion instabilities.Conclusions. Solar Orbiter measurements are consistent with the crossing through a magnetic and plasma structure of cometary origin embedded in the ambient solar wind. We suggest that this corresponds to the magnetotail of one of the fragments of comet ATLAS or to a portion of the tail that was previously disconnected and advected past the spacec
  • Journal article
    Zhao L-L, Zank GP, He JS, Telloni D, Adhikari L, Nakanotani M, Kasper JC, Bale SDet al., 2021,

    MHD and Ion Kinetic Waves in Field-aligned Flows Observed by Parker Solar Probe

    , ASTROPHYSICAL JOURNAL, Vol: 922, ISSN: 0004-637X
  • Journal article
    Ala-Lahti M, Dimmock AP, Pulkkinen T, Good SW, Yordanova E, Turc L, Kilpua EKJet al., 2021,

    Transmission of an ICME Sheath Into the Earth's Magnetosheath and the Occurrence of Traveling Foreshocks

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380
  • Journal article
    Pitna A, Safrankova J, Nemecek Z, Franci L, Pi Get al., 2021,

    A Novel Method for Estimating the Intrinsic Magnetic Field Spectrum of Kinetic-Range Turbulence

    , ATMOSPHERE, Vol: 12
  • Journal article
    Tao J, Wang L, Li G, Wimmer-Schweingruber RF, Salem C, Jian LK, Bale SDet al., 2021,

    Solar Wind ∼0.15-1.5 keV Electrons around Corotating Interaction Regions at 1 au

    , ASTROPHYSICAL JOURNAL, Vol: 922, ISSN: 0004-637X
  • Journal article
    Pecora F, Servidio S, Greco A, Matthaeus WH, McComas DJ, Giacalone J, Joyce CJ, Getachew T, Cohen CMS, Leske RA, Wiedenbeck ME, McNutt RL, Hill ME, Mitchell DG, Christian ER, Roelof EC, Schwadron NA, Bale SDet al., 2021,

    Parker Solar Probe observations of helical structures as boundaries for energetic particles

    , MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 508, Pages: 2114-2122, ISSN: 0035-8711
  • Journal article
    Graven H, Lamb E, Blake D, Khatiwala Set al., 2021,

    Future changes in δ 13 C of dissolved inorganic carbon in the ocean

    , Earth's Future, Vol: 9, Pages: 1-12, ISSN: 2328-4277

    Emissions of carbon dioxide from fossil fuel combustion are reducing the ratio 13C/12C, δ13C, in atmospheric urn:x-wiley:23284277:media:eft2900:eft2900-math-0001 and in the carbon in the ocean and terrestrial biosphere that exchanges with the atmosphere on timescales of decades to centuries. Future changes to fossil fuel emissions vary across different scenarios and may cause decreases of more than 6‰ in atmospheric δ13urn:x-wiley:23284277:media:eft2900:eft2900-math-0002 between 1850 and 2100. The effects of these potential changes on the three-dimensional distribution of δ13C in the ocean has not yet been investigated. Here, we use an ocean biogeochemical-circulation model forced with a range of Shared Socioeconomic Pathway (SSP)-based scenarios to simulate δ13C in ocean dissolved inorganic carbon from 1850 to 2100. In the future, vertical δ13C gradients characteristic of the biological pump are reduced or reversed, relative to the preindustrial period, with the reversal occurring in higher emission scenarios. For the highest emission scenario, SSP5-8.5, surface δ13C in the centre of Pacific subtropical gyres falls from 2.2‰ in 1850 to -3.5‰ by 2100. In lower emission scenarios, δ13C in the surface ocean decreases but then rebounds. The relationship between anthropogenic carbon (Cant) and δ13C in the ocean shows a larger scatter in all scenarios, suggesting that errors in δ13C-based estimates of Cant may increase in the future. These simulations were run with fixed physical forcing and ocean circulation, providing a baseline of predicted δ13C. Further work is needed to investigate the impact of climate-carbon cycle feedbacks on ocean δ13C changes.
  • Journal article
    Lai T-K, Hendricks EA, Yau MK, 2021,

    Long-Term Effect of Barotropic Instability across the Moat in Double-Eyewall Tropical Cyclone–Like Vortices in Forced and Unforced Shallow-Water Models

    , Journal of the Atmospheric Sciences, Vol: 78, Pages: 4103-4126, ISSN: 0022-4928

    <jats:title>Abstract</jats:title><jats:p>Secondary eyewall formation and the ensuing eyewall replacement cycles may take place in mature tropical cyclones (TCs) during part of their lifetime. A better understanding of the underlying dynamics is beneficial to improving the prediction of TC intensity and structure. Previous studies suggested that the barotropic instability (BI) across the moat (aka type-2 BI) can make a substantial contribution to the inner-eyewall decay through the associated eddy radial transport of absolute angular momentum (AAM). Simultaneously, the type-2 BI can also increase the AAM of the outer eyewall. While the previous studies focused on the early stage of the type-2 BI, this paper explores the long-term effect of the type-2 BI and the underlying processes in forced and unforced shallow-water experiments. Under the long-term effect, it will be shown that the inner eyewalls repeatedly weaken and strengthen (while the order is reversed for the outer eyewalls). Sensitivity tests are conducted to examine the sensitivity of the long-term effect of the type-2 BI to different vortex parameters and the strength of the parameterized diabatic heating. Implication of the long-term effect for the intensity changes of the inner and outer eyewalls of real TCs are also discussed.</jats:p>
  • Journal article
    Papini E, Hellinger P, Verdini A, Landi S, Franci L, Montagud-Camps V, Matteini Let al., 2021,

    Properties of Hall-MHD Turbulence at Sub-Ion Scales: Spectral Transfer Analysis

    , ATMOSPHERE, Vol: 12
  • Journal article
    Vasko IY, Alimov K, Phan TD, Bale SD, Mozer FS, Artemyev Aet al., 2021,

    Kinetic-scale Current Sheets in the Solar Wind at 1 au: Properties and the Necessary Condition for Reconnection

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 923, ISSN: 2041-8205
  • Journal article
    Davies EE, Forsyth RJ, Winslow RM, Moestl C, Lugaz Net al., 2021,

    A Catalog of Interplanetary Coronal Mass Ejections Observed by Juno between 1 and 5.4 au

    , ASTROPHYSICAL JOURNAL, Vol: 923, ISSN: 0004-637X
  • Journal article
    Ceppi P, Fueglistaler S, 2021,

    The El Niño–Southern Oscillation pattern effect

    , Geophysical Research Letters, Vol: 48, Pages: 1-9, ISSN: 0094-8276

    El Niño–Southern Oscillation (ENSO) variability is accompanied by out-of-phase anomalies in the top-of-atmosphere tropical radiation budget, with anomalous downward flux (i.e., net radiative heating) before El Niño and anomalous upward flux thereafter (and vice versa for La Niña). Here, we show that these radiative anomalies result mainly from a sea surface temperature (SST) “pattern effect,” mediated by changes in tropical-mean tropospheric stability. These stability changes are caused by SST anomalies migrating from climatologically cool to warm regions over the ENSO cycle. Our results are suggestive of a two-way coupling between SST variability and radiation, where ENSO-induced radiative changes may in turn feed back onto SST during ENSO.
  • Journal article
    Stephan K, Roatsch T, Tosi F, Matz K-D, Kersten E, Wagner R, Molyneux P, Palumbo P, Poulet F, Hussmann H, Barabash S, Bruzzone L, Dougherty M, Gladstone R, Gurvits LI, Hartogh P, Iess L, Wahlund J-E, Wurz P, Witasse O, Grasset O, Altobelli N, Carter J, Cavalie T, d'Aversa E, Della Corte V, Filacchione G, Galli A, Galluzzi V, Gwinner K, Hauber E, Jaumann R, Krohn K, Langevin Y, Lucchetti A, Migliorini A, Piccioni G, Solomonidou A, Stark A, Tobie G, Tubiana C, Vallat C, Van Hoolst Tet al., 2021,

    Regions of interest on Ganymede's and Callisto's surfaces as potential targets for ESA's JUICE mission

    , PLANETARY AND SPACE SCIENCE, Vol: 208, ISSN: 0032-0633
  • Journal article
    Dunlop MW, Dong XC, Wang TY, Eastwood JP, Robert P, Haaland S, Yang YY, Escoubet P, Rong ZJ, Shen C, Fu HS, De Keyser Jet al., 2021,

    Curlometer technique and applications

    , Journal of Geophysical Research: Space Physics, Vol: 126, Pages: 1-29, ISSN: 2169-9380

    We review the range of applications and use of the curlometer, initially developed to analyze Cluster multi-spacecraft magnetic field data; but more recently adapted to other arrays of spacecraft flying in formation, such as MMS small-scale, 4-spacecraft configurations; THEMIS close constellations of 3–5 spacecraft, and Swarm 2–3 spacecraft configurations. Although magnetic gradients require knowledge of spacecraft separations and the magnetic field, the structure of the electric current density (for example, its relative spatial scale), and any temporal evolution, limits measurement accuracy. Nevertheless, in many magnetospheric regions the curlometer is reliable (within certain limits), particularly under conditions of time stationarity, or with supporting information on morphology (for example, when the geometry of the large scale structure is expected). A number of large-scale regions have been covered, such as: the cross-tail current sheet, ring current, the current layer at the magnetopause and field-aligned currents. Transient and smaller scale current structures (e.g., reconnected flux tube or dipolarisation fronts) and energy transfer processes. The method is able to provide estimates of single components of the vector current density, even if there are only two or three satellites flying in formation, within the current region, as can be the case when there is a highly irregular spacecraft configuration. The computation of magnetic field gradients and topology in general includes magnetic rotation analysis and various least squares approaches, as well as the curlometer, and indeed the added inclusion of plasma measurements and the extension to larger arrays of spacecraft have recently been considered.

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