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  • Journal article
    Duan D, He J, Bowen TA, Woodham LD, Wang T, Chen CHK, Mallet A, Bale SDet al., 2021,

    Anisotropy of solar wind turbulence in the inner heliosphere at kinetic scales: PSP observations

    , Letters of the Astrophysical Journal, Vol: 915, Pages: 1-7, ISSN: 2041-8205

    The anisotropy of solar wind turbulence is a critical issue in understanding the physics of energy transfer between scales and energy conversion between fields and particles in the heliosphere. Using the measurement of Parker Solar Probe (PSP), we present an observation of the anisotropy at kinetic scales in the slow, Alfvénic, solar wind in the inner heliosphere. The magnetic compressibility behaves as expected for kinetic Alfvénic turbulence below the ion scale. A steepened transition range is found between the inertial and kinetic ranges in all directions with respect to the local background magnetic field direction. The anisotropy of k⊥ ≫ k∥ is found evident in both transition and kinetic ranges, with the power anisotropy P⊥/P∥ > 10 in the kinetic range leading over that in the transition range and being stronger than that at 1 au. The spectral index varies from αt∥ = −5.7 ± 1.0 to αt⊥ = −3.7 ± 0.3 in the transition range and αk∥ = −3.12 ± 0.22 to αk⊥ = −2.57 ± 0.09 in the kinetic range. The corresponding wavevector anisotropy has the scaling of ${k}_{\parallel }\sim {k}_{\perp }^{0.71\pm 0.17}$ in the transition range, and changes to ${k}_{\parallel }\sim {k}_{\perp }^{0.38\pm 0.09}$ in the kinetic range, consistent with the kinetic Alfvénic turbulence at sub-ion scales.
  • Journal article
    Farrell WM, Rasca AP, MacDowall RJ, Gruesbeck JR, Bale SD, Kasper JCet al., 2021,

    Switchback Boundary Dissipation and Relative Age

    , ASTROPHYSICAL JOURNAL, Vol: 915, ISSN: 0004-637X
  • Journal article
    Madanian H, Schwartz SJ, Fuselier SA, Burgess D, Turner DL, Chen L-J, Desai MI, Starkey MJet al., 2021,

    Direct Evidence for Magnetic Reflection of Heavy Ions from High Mach Number Collisionless Shocks

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 915, ISSN: 2041-8205
  • Journal article
    Gristey JJ, Su W, Loeb NG, Vonder Haar TH, Tornow F, Schmidt KS, Hakuba MZ, Pilewskie P, Russell JEet al., 2021,

    Shortwave radiance to irradiance conversion for earth radiation budget satellite observations: a review

    , Remote Sensing, Vol: 13, ISSN: 2072-4292

    Observing the Earth radiation budget (ERB) from satellites is crucial for monitoring and understanding Earth’s climate. One of the major challenges for ERB observations, particularly for reflected shortwave radiation, is the conversion of the measured radiance to the more energetically relevant quantity of radiative flux, or irradiance. This conversion depends on the solar-viewing geometry and the scene composition associated with each instantaneous observation. We first outline the theoretical basis for algorithms to convert shortwave radiance to irradiance, most commonly known as empirical angular distribution models (ADMs). We then review the progression from early ERB satellite observations that applied relatively simple ADMs, to current ERB satellite observations that apply highly sophisticated ADMs. A notable development is the dramatic increase in the number of scene types, made possible by both the extended observational record and the enhanced scene information now available from collocated imager information. Compared with their predecessors, current shortwave ADMs result in a more consistent average albedo as a function of viewing zenith angle and lead to more accurate instantaneous and mean regional irradiance estimates. One implication of the increased complexity is that the algorithms may not be directly applicable to observations with insufficient accompanying imager information, or for existing or new satellite instruments where detailed scene information is not available. Recent advances that complement and build on the base of current approaches, including machine learning applications and semi-physical calculations, are highlighted.
  • Journal article
    Halekas JS, Bercic L, Whittlesey P, Larson DE, Livi R, Berthomier M, Kasper JC, Case AW, Stevens ML, Bale SD, MacDowall RJ, Pulupa MPet al., 2021,

    The Sunward Electron Deficit: A Telltale Sign of the Sun's Electric Potential

    , ASTROPHYSICAL JOURNAL, Vol: 916, ISSN: 0004-637X
  • Journal article
    Wang R, Vasko IY, Mozer FS, Bale SD, Kuzichev IV, Artemyev AV, Steinvall K, Ergun R, Giles B, Khotyaintsev Y, Lindqvist P-A, Russell CT, Strangeway Ret al., 2021,

    Electrostatic Solitary Waves in the Earth's Bow Shock: Nature, Properties, Lifetimes, and Origin

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380
  • Journal article
    Yao Z, Dunn WR, Woodfield EE, Clark G, Mauk BH, Ebert RW, Grodent D, Bonfond B, Pan D, Rae IJ, Ni B, Guo R, Branduardi-Raymont G, Wibisono AD, Rodriguez P, Kotsiaros S, Ness J-U, Allegrini F, Kurth WS, Gladstone GR, Kraft R, Sulaiman AH, Manners H, Desai RT, Bolton SJet al., 2021,

    Revealing the source of Jupiter's x-ray auroral flares

    , SCIENCE ADVANCES, Vol: 7, ISSN: 2375-2548
  • Journal article
    Chen L, Ma B, Wu D, Zhao G, Tang J, Bale SDet al., 2021,

    An Interplanetary Type IIIb Radio Burst Observed by Parker Solar Probe and Its Emission Mechanism

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 915, ISSN: 2041-8205
  • Journal article
    Kuhn- Regnier A, Voulgarakis A, Nowack P, Forkel M, Prentice IC, Harrison Set al., 2021,

    The importance of antecedent vegetation and drought conditions as global drivers of burnt areas

    , Biogeosciences, Vol: 18, Pages: 3861-3879, ISSN: 1726-4170

    The seasonal and longer-term dynamics of fuel accumulation affect fire seasonality and the occurrence of extreme wildfires. Failure to account for their influence may help to explain why state-of-the-art fire models do not simulate the length and timing of the fire season or interannual variability in burnt area well. We investigated the impact of accounting for different timescales of fuel production and accumulation on burnt area using a suite of random forest regression models that included the immediate impact of climate, vegetation, and human influences in a given month and tested the impact of various combinations of antecedent conditions in four productivity-related vegetation indices and in antecedent moisture conditions. Analyses were conducted for the period from 2010 to 2015 inclusive. Inclusion of antecedent vegetation conditions representing fuel build-up led to an improvement of the global, climatological out-of-sample R2 from 0.579 to 0.701, but the inclusion of antecedent vegetation conditions on timescales ≥ 1 year had no impact on simulated burnt area. Current moisture levels were the dominant influence on fuel drying. Additionally, antecedent moisture levels were important for fuel build-up. The models also enabled the visualisation of interactions between variables, such as the importance of antecedent productivity coupled with instantaneous drying. The length of the period which needs to be considered varies across biomes; fuel-limited regions are sensitive to antecedent conditions that determine fuel build-up over longer time periods (∼ 4 months), while moisture-limited regions are more sensitive to current conditions that regulate fuel drying.
  • Journal article
    Kuhn-Régnier A, Voulgarakis A, Nowack P, Forkel M, Prentice IC, Harrison SPet al., 2021,

    Quantifying the Importance of antecedent fuel-related vegetationproperties for burnt area using random forests

    , Biogeosciences, Vol: 8, ISSN: 1726-4170

    The seasonal and longer-term dynamics of fuel accumulation affect fire seasonality and the occurrence of extreme wildfires. Failure to account for their influence mayhelp to explain why state-of-the-art fire models do not simulate the length and timing of the fire season or interannual variability in burnt area well. We investigated the impact of accounting for different timescales of fuel production and accumulation on burnt area using a suite of random forest regression models that included the immediateimpact of climate, vegetation, and human influences in agiven month and tested the impact of various combinationsof antecedent conditions in four productivity-related vegetation indices and in antecedent moisture conditions. Analyses were conducted for the period from 2010 to 2015 inclusive. Inclusion of antecedent vegetation conditions representing fuel build-up led to an improvement of the global,climatological out-of-sample R2from 0.579 to 0.701, but theinclusion of antecedent vegetation conditions on timescales≥ 1 year had no impact on simulated burnt area. Currentmoisture levels were the dominant influence on fuel drying. Additionally, antecedent moisture levels were importantfor fuel build-up. The models also enabled the visualisationof interactions between variables, such as the importanceof antecedent productivity coupled with instantaneous drying. The length of the period which needs to be consideredvaries across biomes; fuel-limited regions are sensitive to antecedent conditions that determine fuel build-up over longertime periods (∼ 4 months), while moisture-limited regionsare more sensitive to current conditions that regulate fuel drying.
  • Journal article
    Hall RJ, Mitchell DM, Seviour WJM, Wright CJet al., 2021,

    Persistent Model Biases in the CMIP6 Representation of Stratospheric Polar Vortex Variability

    , JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, Vol: 126, ISSN: 2169-897X
  • Journal article
    Pal S, Kilpua E, Good S, Pomoell J, Price DJet al., 2021,

    Uncovering erosion effects on magnetic flux rope twist

    , ASTRONOMY & ASTROPHYSICS, Vol: 650, ISSN: 0004-6361
  • Journal article
    Malaspina DM, Wilson LB, Ergun RE, Bale SD, Bonnell JW, Goodrich K, Goetz K, Harvey PR, MacDowall RJ, Pulupa M, Halekas J, Case A, Kasper JC, Larson D, Stevens M, Whittlesey Pet al., 2021,

    Electron Bernstein waves and narrowband plasma waves near the electron cyclotron frequency in the near-Sun solar wind

    , ASTRONOMY & ASTROPHYSICS, Vol: 650, ISSN: 0004-6361
  • Journal article
    Cattell C, Short B, Breneman A, Halekas J, Whittesley P, Larson D, Kasper JC, Stevens M, Case T, Moncuquet M, Bale S, Bonnell J, de Wit TD, Goetz K, Harvey P, MacDowall R, Malaspina D, Maksimovic M, Pulupa M, Goodrich Ket al., 2021,

    Narrowband oblique whistler-mode waves: comparing properties observed by Parker Solar Probe at <0.3 AU and STEREO at 1 AU

    , ASTRONOMY & ASTROPHYSICS, Vol: 650, ISSN: 0004-6361
  • Journal article
    Finley AJ, McManus MD, Matt SP, Kasper JC, Korreck KE, Case AW, Stevens ML, Whittlesey P, Larson D, Livi R, Bale SD, de Wit TD, Goetz K, Harvey PR, MacDowall RJ, Malaspina DM, Pulupa Met al., 2021,

    The contribution of alpha particles to the solar wind angular momentum flux in the inner heliosphere

    , ASTRONOMY & ASTROPHYSICS, Vol: 650, ISSN: 0004-6361
  • Journal article
    Harra L, Brooks DH, Bale SD, Mandrini CH, Barczynski K, Sharma R, Badman ST, Dominguez SV, Pulupa Met al., 2021,

    The active region source of a type III radio storm observed by Parker Solar Probe during encounter 2

    , ASTRONOMY & ASTROPHYSICS, Vol: 650, ISSN: 0004-6361
  • Journal article
    Schwadron NA, Joyce CJ, Aly A, Cohen CMS, Desai M, McComas DJ, Niehof JT, Mobius E, Lee M, Bower J, Bale S, Case A, Christian ER, Davis AJ, de Wet W, Goetz K, Giacalone J, Hill ME, Allen R, Kasper JC, Korreck K, Leske RA, Malandraki O, Matthaeus WH, McNutt RL, Mewaldt RA, Mitchell DG, Pulupa M, Rankin JS, Roelof EC, Stone EC, Szalay JR, Wiedenbeck MEet al., 2021,

    A new view of energetic particles from stream interaction regions observed by Parker Solar Probe

    , ASTRONOMY & ASTROPHYSICS, Vol: 650, ISSN: 0004-6361
  • Journal article
    Quaas J, Gryspeerdt E, Vautard R, Boucher Oet al., 2021,

    Climate impact of aircraft-induced cirrus assessed from satellite observations before and during COVID-19

    , Environmental Research Letters, Vol: 16, Pages: 1-6, ISSN: 1748-9326

    Aircraft produce condensation trails, which are thought to increase high-level cloudiness under certain conditions. Howeverthe magnitude of such an effect and whether this contributes substantially to the radiative forcing due to the aviation sectorremain uncertain. The very substantial, near-global reduction in air traffic in response to the COVID-19 outbreak offers anunprecedented opportunity to identify the anthropogenic contribution to the observed cirrus coverage and thickness. Here weshow, using an analysis of satellite observations for the period March-May 2020, that in the 20% of the Northern Hemispheremid-latitudes with the largest air traffic reduction, cirrus fraction was reduced by ~9 ± 1.5% on average, and cirrus emissivitywas reduced by ~2 ±5% relative to what they should have been with normal air traffic. The changes are corroborated by aconsistent estimate based on linear trends over the period 2011 – 2019. The change in cirrus translates to a global radiativeforcing of 61 ±39 mWm-2. This estimate is somewhat smaller than previous assessments.
  • Journal article
    Phan TD, Lavraud B S J, Halekas, Øieroset M, Drake JF, Eastwood JP, Shay MA, Bale SD, Larson D, Livi R, Whittlesey PL, Rahmati A, Pulupa M, McManus MD, Verniero JL, Bonnell JW, Stevens M, Case AWet al., 2021,

    Prevalence of magnetic reconnection in the near-Sun heliospheric current sheet

    , Astronomy & Astrophysics, Vol: 650, Pages: 1-14, ISSN: 0004-6361

    During three of its first five orbits around the Sun, Parker Solar Probe (PSP) crossed the large-scale Heliospheric Current Sheet (HCS)multiple times and provided unprecedented detailed plasma and field observations of the near-Sun HCS. We report the commondetections by PSP of reconnection exhaust signatures in the HCS at heliocentric distances of 29.5-107 solar radii during Encounters1, 4 and 5. Both sunward and antisunward-directed reconnection exhausts were observed. In the sunward reconnection exhausts,PSP detected counterstreaming strahl electrons, indicating that HCS reconnection resulted in the formation of closed magnetic fieldlines with both ends connected to the Sun. In the antisunward exhausts, PSP observed dropouts of strahl electrons, consistent withthe reconnected HCS field lines being disconnected from the Sun. The common detection of reconnection in the HCS suggests thatreconnection is almost always active in the HCS near the Sun. Furthermore, the occurrence of multiple long-duration partial crossingsof the HCS suggests that HCS reconnection could produce chains of large bulges with spatial dimensions of up to several solarradii. The finding of the prevalence of reconnection in the HCS is somewhat surprising since PSP has revealed that the HCS is muchthicker than the kinetic scales required for reconnection onset. The observations are also in stark contrast with the apparent absenceof reconnection in most of the small-scale and much more intense current sheets encountered near perihelia, many of which areassociated with ‘switchbacks’. Thus, the PSP findings suggest that large-scale dynamics either locally in the solar wind or within thecoronal source of the HCS (at the tip of helmet streamers) plays a critical role in triggering reconnection onset.
  • Journal article
    Fargette N, Lavraud B, Rouillard A, Eastwood JP, Bale SD, Phan T, Øieroset M, Halekas JS, Kasper J, Berthomier M, Case AW, Korreck KE, Larson DE, Louarn P, Malaspina D, Pulupa M, Stevens ML, Whittlesey PLet al., 2021,

    Magnetic increases with central current sheets: Observations with Parker Solar Probe

    , Astronomy & Astrophysics, Vol: 650, Pages: 1-12, ISSN: 0004-6361

    Aims. We report the observation by Parker Solar Probe (PSP) of magnetic structures in the solar wind that present a strong peak intheir magnetic field magnitude with an embedded central current sheet. Similar structures have been observed, either at the Earth’smagnetopause and called interlinked flux tubes, or in the solar wind and called interplanetary field enhancements.Methods. In this work, we first investigate two striking events in detail; one occurred in the regular slow solar wind on November 2,2018 and the other was observed during a heliospheric current sheet crossing on November 13, 2018. They both show the presenceof a central current sheet with a visible ion jet and general characteristics consistent with the occurrence of magnetic reconnection.We then performed a survey of PSP data from encounters 1 to 4 and find 18 additional events presenting an increase in the magneticfield magnitude of over 30% and a central current sheet. We performed a statistical study on the 20 "magnetic increases with centralcurrent sheet" (MICCS), with 13 observed in the regular slow solar wind with a constant polarity (i.e., identical strahl direction), and7 which were specifically observed near a heliospheric current sheet (HCS) crossing.Results. We analyze and discuss the general properties of the structures, including the duration, location, amplitude, and magnetictopology, as well as the characteristics of their central current sheet. We find that the latter has a preferential orientation in the TNplane of the RTN frame. We also find no significant change in the dust impact rate in the vicinity of the MICCS under study, leadingus to conclude that dust probably plays no role in the MICCS formation and evolution. Our findings are overall consistent with adouble flux tube-configuration that would result from initially distinct flux tubes which interact during solar wind propagation.
  • Journal article
    Akhavan-Tafti M, Kasper J, Huang J, Bale Set al., 2021,

    Discontinuity analysis of the leading switchback transition regions

    , ASTRONOMY & ASTROPHYSICS, Vol: 650, ISSN: 0004-6361
  • Journal article
    Cohen CMS, Christian ER, Cummings AC, Davis AJ, Desai M, de Nolfo GA, Giacalone J, Hill ME, Joyce CJ, Labrador AW, Leske RA, Matthaeus WH, McComas DJ, McNutt RL, Mewaldt RA, Mitchell DG, Mitchell JG, Rankin JS, Roelof EC, Schwadron NA, Stone EC, Szalay JR, Wiedenbeck ME, Vourlidas A, Bale SD, Pulupa M, MacDowall RJet al., 2021,

    Parker Solar Probe observations of He/H abundance variations in SEP events inside 0.5 au

    , ASTRONOMY & ASTROPHYSICS, Vol: 650, ISSN: 0004-6361
  • Journal article
    Vech D, Martinovic MM, Klein KG, Malaspina DM, Bowen TA, Verniero JL, Paulson K, de Wit TD, Kasper JC, Huang J, Stevens ML, Case AW, Korreck K, Mozer FS, Goodrich KA, Bale SD, Whittlesey PL, Livi R, Larson DE, Pulupa M, Bonnell J, Harvey P, Goetz K, MacDowall Ret al., 2021,

    Wave-particle energy transfer directly observed in an ion cyclotron wave

    , ASTRONOMY & ASTROPHYSICS, Vol: 650, ISSN: 0004-6361
  • Journal article
    Allen RC, Ho GC, Jian LK, Vines SK, Bale SD, Case AW, Hill ME, Joyce CJ, Kasper JC, Korreck KE, Malaspina DM, McComas DJ, McNutt R, Mostl C, Odstrcil D, Raouafi N, Schwadron NA, Stevens MLet al., 2021,

    A living catalog of stream interaction regions in the Parker Solar Probe era

    , ASTRONOMY & ASTROPHYSICS, Vol: 650, ISSN: 0004-6361
  • Journal article
    Cattell C, Glesener L, Leiran B, Dombeck J, Goetz K, Oliveros JCM, Badman ST, Pulupa M, Bale SDet al., 2021,

    Periodicities in an active region correlated with Type Ill radio bursts observed by Parker Solar Probe

    , ASTRONOMY & ASTROPHYSICS, Vol: 650, ISSN: 0004-6361
  • Journal article
    Chen CHK, Chandran BDG, Woodham LD, Jones SI, Perez JC, Bourouaine S, Bowen TA, Klein KG, Moncuquet M, Kasper JC, Bale SDet al., 2021,

    The near-Sun streamer belt solar wind: turbulence and solar wind acceleration

    , Astronomy & Astrophysics, Vol: 650, Pages: 1-6, ISSN: 0004-6361

    The fourth orbit of Parker Solar Probe (PSP) reached heliocentric distances down to 27.9 R⊙, allowing solar wind turbulence and acceleration mechanisms to be studied in situ closer to the Sun than previously possible. The turbulence properties were found to be significantly different in the inbound and outbound portions of PSP’s fourth solar encounter, which was likely due to the proximity to the heliospheric current sheet (HCS) in the outbound period. Near the HCS, in the streamer belt wind, the turbulence was found to have lower amplitudes, higher magnetic compressibility, a steeper magnetic field spectrum (with a spectral index close to –5/3 rather than –3/2), a lower Alfvénicity, and a ‘1∕f’ break at much lower frequencies. These are also features of slow wind at 1 au, suggesting the near-Sun streamer belt wind to be the prototypical slow solar wind. The transition in properties occurs at a predicted angular distance of ≈4° from the HCS, suggesting ≈8° as the full-width of the streamer belt wind at these distances. While the majority of the Alfvénic turbulence energy fluxes measured by PSP are consistent with those required for reflection-driven turbulence models of solar wind acceleration, the fluxes in the streamer belt are significantly lower than the model predictions, suggesting that additional mechanisms are necessary to explain the acceleration of the streamer belt solar wind.
  • Journal article
    Laker R, Horbury TS, Bale SD, Matteini L, Woolley T, Woodham LD, Badman ST, Pulupa M, Kasper JC, Stevens M, Case AW, Korreck KEet al., 2021,

    Statistical analysis of orientation, shape, and size of solar wind switchbacks

    , Astronomy & Astrophysics, Vol: 650, Pages: 1-7, ISSN: 0004-6361

    One of the main discoveries from the first two orbits of Parker Solar Probe(PSP) was the presence of magnetic switchbacks, whose deflections dominated themagnetic field measurements. Determining their shape and size could provideevidence of their origin, which is still unclear. Previous work with a singlesolar wind stream has indicated that these are long, thin structures althoughthe direction of their major axis could not be determined. We investigate ifthis long, thin nature extends to other solar wind streams, while determiningthe direction along which the switchbacks within a stream were aligned. We tryto understand how the size and orientation of the switchbacks, along with theflow velocity and spacecraft trajectory, combine to produce the observedstructure durations for past and future orbits. We searched for the alignmentdirection that produced a combination of a spacecraft cutting direction andswitchback duration that was most consistent with long, thin structures. Theexpected form of a long, thin structure was fitted to the results of the bestalignment direction, which determined the width and aspect ratio of theswitchbacks for that stream. The switchbacks had a mean width of $50,000 \,\rm{km}$, with an aspect ratio of the order of $10$. We find that switchbacksare not aligned along the background flow direction, but instead aligned alongthe local Parker spiral, perhaps suggesting that they propagate along themagnetic field. Since the observed switchback duration depends on how thespacecraft cuts through the structure, the duration alone cannot be used todetermine the size or influence of an individual event. For future PSP orbits,a larger spacecraft transverse component combined with more radially alignedswitchbacks will lead to long duration switchbacks becoming less common.
  • Journal article
    Woodham L, Horbury T, Matteini L, Woolley T, Laker R, Bale S, Nicolaou G, Stawarz J, Stansby D, Hietala H, Larson D, Livi R, Verniero J, McManus M, Kasper J, Korreck K, Raouafi N, Moncuquet M, Pulupa Met al., 2021,

    Enhanced proton parallel temperature inside patches of switchbacks in the inner heliosphere

    , Astronomy and Astrophysics: a European journal, Vol: 650, Pages: 1-7, ISSN: 0004-6361

    Context. Switchbacks are discrete angular deflections in the solar wind magnetic field that have been observed throughout the helio-sphere. Recent observations by Parker Solar Probe(PSP) have revealed the presence of patches of switchbacks on the scale of hours to days, separated by ‘quieter’ radial fields. Aims. We aim to further diagnose the origin of these patches using measurements of proton temperature anisotropy that can illuminate possible links to formation processes in the solar corona. Methods. We fit 3D bi-Maxwellian functions to the core of proton velocity distributions measured by the SPAN-Ai instrument onboard PSP to obtain the proton parallel, Tp,‖, and perpendicular, Tp,⊥, temperature. Results. We show that the presence of patches is highlighted by a transverse deflection in the flow and magnetic field away from the radial direction. These deflections are correlated with enhancements in Tp,‖, while Tp,⊥remains relatively constant. Patches sometimes exhibit small proton and electron density enhancements. Conclusions. We interpret that patches are not simply a group of switchbacks, but rather switchbacks are embedded within a larger-scale structure identified by enhanced Tp,‖that is distinct from the surrounding solar wind. We suggest that these observations are consistent with formation by reconnection-associated mechanisms in the corona.
  • Journal article
    Drake JF, Agapitov O, Swisdak M, Badman ST, Bale SD, Horbury TS, Kasper JC, MacDowall RJ, Mozer FS, Phan TD, Pulupa M, Szabo A, Velli Met al., 2021,

    Are switchbacks signatures of magnetic flux ropes generated by interchange reconnection in the corona?

    , Astronomy and Astrophysics: a European journal, Vol: 650, Pages: 1-8, ISSN: 0004-6361

    The structure of magnetic flux ropes injected into the solar wind duringreconnection in the coronal atmosphere is explored with particle-in-cellsimulations and compared with {\it in situ} measurements of magnetic"switchbacks" from the Parker Solar Probe. We suggest that multi-x-linereconnection between open and closed flux in the corona will inject flux ropesinto the solar wind and that these flux ropes can convect outward over longdistances before disintegrating. Simulations that explore the magneticstructure of flux ropes in the solar wind reproduce key features of the"switchback" observations: a rapid rotation of the radial magnetic field intothe transverse direction (a consequence of reconnection with a strong guidefield); and the potential to reverse the radial field component. The potentialimplication of the injection of large numbers of flux ropes in the coronalatmosphere for understanding the generation of the solar wind is discussed.
  • Journal article
    Halekas JS, Whittlesey PL, Larson DE, McGinnis D, Bale SD, Berthomier M, Case AW, Chandran BDG, Kasper JC, Klein KG, Korreck KE, Livi R, MacDowall RJ, Maksimovic M, Malaspina DM, Matteini L, Pulupa MP, Stevens MLet al., 2021,

    Electron heat flux in the near-Sun environment

    , ASTRONOMY & ASTROPHYSICS, Vol: 650, ISSN: 0004-6361

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