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Journal articleSparks N, Toumi R, 2022,
A physical model of tropical cyclone central pressure filling at landfall
, Journal of the Atmospheric Sciences, Vol: 79, Pages: 2585-2599, ISSN: 0022-4928We derive a simple physically based analytic model which describes the pressure filling of a tropical cyclone (TC) over land. Starting from the axisymmetric mass continuity equation in cylindrical coordinates we derive that the half-life decay of the pressure deficit between the environmentand TC centre is proportional to the initial radius of maximum surface wind speed. The initial pressure deficit and column-mean radial inflow speed into the core are the other key variables. The assumptions made in deriving the model are validated against idealised numerical simulations of TC decay over land. Decay half-lives predicted from a range of initial TC states are tested against the idealized simulations and are in good agreement. Dry idealised TC decay simulations show that without latent convective heating, the boundary layer decouples from the vortex above leading to a fast decay of surface winds while a mid-level vortex persists.
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Journal articleZhao J, Malaspina DM, de Wit TD, et al., 2022,
Broadband Electrostatic Waves near the Lower-hybrid Frequency in the Near-Sun Solar Wind Observed by the Parker Solar Probe
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 938, ISSN: 2041-8205- Author Web Link
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- Citations: 1
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Journal articleSchwartz SJ, Goodrich KA, Wilson LB, et al., 2022,
Energy Partition at Collisionless Supercritical Quasi-Perpendicular Shocks
, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 127, ISSN: 2169-9380- Author Web Link
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- Citations: 5
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Journal articleBrandt PC, Provornikova EA, Cocoros A, et al., 2022,
Interstellar Probe: Humanity?s exploration of the Galaxy Begins
, ACTA ASTRONAUTICA, Vol: 199, Pages: 364-373, ISSN: 0094-5765- Author Web Link
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- Citations: 14
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Journal articleOwen CJ, Abraham JB, Nicolaou G, et al., 2022,
Solar Orbiter SWA Observations of Electron Strahl Properties Inside 1 AU
, UNIVERSE, Vol: 8- Author Web Link
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- Citations: 3
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Journal articleWells CD, Kasoar M, Bellouin N, et al., 2022,
Supplementary material to "Local and remote climate impacts of future African aerosol emissions"
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Journal articleAgiwal O, Moore L, Martinis C, et al., 2022,
First Steps Towards a New Saturn Ionosphere Model Including Ring-Planet Coupling and Electrodynamics
<jats:p>&lt;div&gt;&lt;div&gt;&lt;div&gt;&lt;div&gt;The Cassini Grand Finale revealed that there is still much that we do not understand about Saturn&amp;#8217;s upper atmosphere. In-situ observations reveal highly complex coupling between the planetary atmosphere and rings and inter-hemispheric electrodynamic coupling at latitudes that are magnetically connected to the intra D-ring region in the magnetosphere. Current Saturn models are ill-suited to treating electrodynamics and ring-planet interactions at Saturn. Thus, we adapt SAMI, a well-known terrestrial ionosphere model that is flux-tube based and already includes electrodynamics, to Saturn, with the aim of using it in conjunction with existing Saturn models such as the STIM-GCM (Saturn Thermosphere Ionosphere Model) to decipher the long-standing unexplained morphologies in Saturn&amp;#8217;s ionosphere and investigate the ring-atmosphere coupling and electrodynamics revealed by the Cassini end-of-mission data. We will present initial results having adapted SAMI to Saturn, showing the full extent of the atmospheric chemistry and model capabilities at present. We will discuss future directions of development towards the construction of the new model capable of resolving the complex ring-atmosphere coupling and electrodynamics, and the possibility of adapting this model to other planets.&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;</jats:p>
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Journal articleKaweeyanun N, Masters A, 2022,
Can Ganymede's magnetopause help us probe its subsurface ocean?
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Journal articleGrant S, Jones G, Owen C, et al., 2022,
The Prediction of, and Results from Solar Orbiter's encounter with Comet C/2021 A1 (Leonard).
<jats:p>&lt;p&gt;As the solar wind encounters a comet, ionized gas released from the nucleus propagates away from the Sun with the wind, forming the ion tail of the comet that can stretch for multiple astronomical units. The transport of cometary material antisunward of the comet provides opportunities to measure the cometary composition and plasma interactions at a significant distance from a comet&amp;#8217;s nucleus. Serendipitous crossings by spacecraft of comets&amp;#8217; ion tails is a surprisingly commonplace occurrence, but can go unnoticed, as any measured plasma fluctuations can be small.&lt;/p&gt;&lt;p&gt;Using the measured flow of the solar wind at the spacecraft, we can estimate the motion of the solar plasma upstream of the spacecraft, and compare this trajectory with the locations of known comets. This method can uncover previously unnoticed ion tail encounters and predict future encounters.&lt;/p&gt;&lt;p&gt;In December 2021, while comet C/2021 A1 (Leonard) traversed the ecliptic plane, sunward of the spacecraft Solar Orbiter, the spacecraft was immersed in the comet&amp;#8217;s ion tail. This encounter was predicted using a range of estimated solar wind velocities to estimate the motion of solar wind plasma to the spacecraft. A wealth of data was collected during the encounter, including results from multiple instruments that support the prediction. We present data returned from the SWA and magnetometer instruments, providing information on the structure of the induced magnetotail. Additionally, images of comet Leonard&amp;#8217;s ion tail from other spacecraft during the encounter provide a uniquely complete picture of the tail crossing.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;em&gt;Fig: Orbital configuration of comet Leonard and Sola
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Conference paperStephenson P, Galand M, Deca J, et al., 2022,
Cold electrons at a weakly outgassing comet
, Europlanet Science Congress 2022, Publisher: Copernicus GmbH -
Journal articleDipu S, Schwarz M, Ekman AML, et al., 2022,
Exploring satellite-derived relationships between cloud droplet number concentration and liquid water path using a large- domain large-eddy simulation
, Tellus Series B: Chemical and Physical Meteorology, Vol: 74, Pages: 176-188, ISSN: 0280-6509Important 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 the adiabatic assumption to derive the Nd, we have also considered adiabatic Nd (NAd) from the LES model for comparison. The joint histogram analysis shows that the NAd-LWP relationship in the LES model and the satellite is in approximate agreement. In both cases, the peak conditional probability (CP) is confined to lower NAd and LWP; the corresponding mean LWP (LWP) shows a weak relation with NAd. The CP shows a larger spread at higher NAd (>50 cm–3), and the LWP increases non-monotonically with increasing NAd in both cases. Nevertheless, both lack the negative NAd-LWP relationship at higher NAd, the entrainment effect on cloud droplets. In contrast, the model simulated Nd-LWP clearly illustrates a much more nonlinear (an increase in LWP with increasing Nd and a decrease in LWP at higher Nd) relationship, which clearly depicts the cloud lifetime and the entrainment effect. Additionally, our analysis demonstrates a regime dependency (marine and continental) in the NAd-LWP relation from the satellite retrievals. Comparing local vs large-scale statistics from satellite data shows that continental clouds exhibit only a weak nonlinear NAd-LWP relationship. Hence a regime-based Nd-LWP analysis is even more relevant when it comes to warm continental clouds and their comparison to satellite retrievals.
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Journal articleBuitrago-Casas JC, Glesener L, Christe S, et al., 2022,
The faintest solar coronal hard X-rays observed with FOXSI
, ASTRONOMY & ASTROPHYSICS, Vol: 665, ISSN: 0004-6361- Author Web Link
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- Citations: 2
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Journal articleGryspeerdt E, Glassmeier F, Feingold G, et al., 2022,
Observing short timescale cloud development to constrain aerosol-cloud interactions
, Atmospheric Chemistry and Physics, Vol: 22, Pages: 11727-11738, ISSN: 1680-7316The aerosol impact on liquid water path (LWP) is a key uncertainty in the overall climate impact of aerosol. However, despite a significant effort in this area, the size of the effect remains poorly constrained, and even the sign is unclear. Recent studies have shown that the relationship between droplet number concentration (Nd ) and LWP is an unreliable measure of theimpact of Nd variations on LWP due to the difficulty in establishing causality. In this work, we use satellite observations of the short-term development of clouds to examine the role of Nd perturbations in LWP variations. Similar to previous studies, an increase followed by a general decrease in LWP with increasing Nd is observed, suggesting an overall negative LWP response to Nd and a warming LWP adjustment to aerosol. However, the Nd also responds to the local environment, with aerosol production, entrainment from the free troposphere and wet scavenging all acting to modify the Nd . Many of these effects act to further steepen the Nd -LWP relationship and obscure the causal Nd impact on LWP. Using the temporal development of clouds to account for these feedbacks in the Nd -LWP system, a weaker negative Nd -LWP relationship is observed over most of the globe. This relationship is highly sensitive to the initial cloud state, illuminating the roles of different processes in shaping the Nd -LWP relationship. The nature of the current observing system limits this work toa single time period for observations, highlighting the need for more frequent observations of key cloud properties to constrain cloud behaviour at process timescales.
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Journal articleCorti C, Whitman K, Desai R, et al., 2022,
Galactic Cosmic Rays and Solar Energetic Particles in Cis-Lunar Space: Need for contextual energetic particle measurements at Earth and supporting distributed observations
, White Paper submitted to Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033 -
Journal articleRuohotie J, Kilpua EKJ, Good SW, et al., 2022,
Small-scale flux ropes in ICME sheaths
, FRONTIERS IN ASTRONOMY AND SPACE SCIENCES, Vol: 9, ISSN: 2296-987X- Author Web Link
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- Citations: 1
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Journal articleEggington J, Coxon J, Shore R, et al., 2022,
Response timescales of the magnetotail current sheet during a geomagnetic storm: global MHD simulations
, Frontiers in Astronomy and Space Sciences, Vol: 9, Pages: 1-17, ISSN: 2296-987XThe response of the Earth’s magnetotail current sheet to the external solar wind driver is highly time-dependent and asymmetric. For example, the current sheet twists in response to variations in the By component of the interplanetary magnetic field (IMF), and is hinged by the dipole tilt. Understanding the timescales over which these asymmetries manifest is of particular importance during geomagnetic storms when the dynamics of the tail control substorm activity. To investigate this, we use the Gorgon MHD model to simulate a geomagnetic storm which commenced on 3 May 2014, and was host to multiple By and Bz reversals and a prolonged period of southward IMF driving. We find that the twisting of the current sheet is well-correlated to IMF By throughout the event, with the angle of rotation increasing linearly with downtail distance and being morepronounced when the tail contains less open flux. During periods of southward IMF the twisting of the central current sheet responds most strongly at a timelag of ∼ 100 min for distances beyond 20 RE, consistent with the 1-2 hr convection timescale identified in the open flux content. Under predominantly northward IMF the response of the twisting is bimodal, with the strongest correlations between 15-40 RE downtail being at a shorter timescale of ∼ 30 min consistent with that estimated for induced By due to wave propagation, compared to a longer timescale of ∼ 3 hr further downtail again attributed to convection. This indicates that asymmetries in the magnetotail communicated by IMF By are influenced mostly by global convection during strong solar wind driving, but that more prompt induced By effects can dominate in the near-Earth tail and during periods of weaker driving. These results provide new insight into the characteristic timescales of solar wind-magnetosphere-ionosphere coupling.
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Journal articleNair R, Halekas JS, Whittlesey PL, et al., 2022,
Switchbacks in the Young Solar Wind: Electron Evolution Observed inside Switchbacks between 0.125 au and 0.25 au
, ASTROPHYSICAL JOURNAL, Vol: 936, ISSN: 0004-637X- Author Web Link
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- Citations: 1
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Conference paperStephenson P, Altwegg K, Beth A, et al., 2022,
The source of electrons at a weakly outgassing comet
, Publisher: Copernicus GmbH<jats:p>&lt;p&gt;The Rosetta spacecraft escorted comet 67P/Churyumov-Gerasimenko for two years along its orbit, from Aug 2014 to Sep 2016, observing the evolution of the comet from a close perspective. The Rosetta Plasma Consortium (RPC) monitored the plasma environment at the spacecraft throughout the escort phase.&lt;/p&gt;&lt;p&gt;Cometary electrons are produced by ionization of the neutral gas coma. This occurs through photoionization by extreme ultraviolet photons, and through electron-impact ionization (EII) by collisions of energetic electrons with the coma. Far from perihelion, EII is, at times, more prevalent than photoionization (Galand et al., 2016; Heritier et al., 2018), but the EII frequency has not been assessed across the whole mission. The source of the cometary electrons, and the origin of the ionizing electrons is still unclear.&lt;/p&gt;&lt;p&gt;We have calculated the electron impact ionization (EII) frequency throughout the Rosetta mission and at its location from measurements of RPC&amp;#8217;s Ion and Electron Sensor (RPC/IES). EII ionization is confirmed as the dominant source of cometary electrons and ions when far from perihelion but is much more variable than photoionization. We compare the EII frequency with properties of the neutral coma and cometary plasma to identify key drivers of the energetic electron population. The EII frequency is structured by outgassing rate and magnetic field strength.&lt;/p&gt;&lt;p&gt;The first 3D collision model of electrons at a comet (Stephenson et al. 2022) is also utilised to assess the origin of electrons within the coma. The model uses self-consistently calculated electric and magnetic fields from a fully-kinetic and collisionless Particle-in-Cell model (Deca et al. 2017, 2019)as an input. The modelling approach confirms cometary electrons are produced by impacts of energetic e
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Conference paperLewis Z, Beth A, Altwegg K, et al., 2022,
Ionospheric composition of comet 67P near perihelion with multi-instrument Rosetta datasets
, Publisher: Copernicus GmbH<jats:p>&lt;p&gt;The European Space Agency Rosetta mission escorted comet 67P/Churyumov-Gerasimenko for two years, during which it acquired an extensive dataset, revealing unprecedented detail about the neutral and plasma environment of the coma. The measurements were made over a large range of heliocentric distances, and therefore of outgassing activities, as Rosetta witnessed 67P evolve from a low-activity icy body at 3.8 AU to a dynamic object with large-scale plasma structures and rich ion and neutral chemistry near perihelion at 1.2 AU. One such plasma structure is the diamagnetic cavity, a region of negligible magnetic field surrounding the comet nucleus. It is formed through the interaction of the unmagnetized outwardly expanding cometary plasma with the incoming solar wind. This region was encountered many times by Rosetta between April 2015 and February 2016, as the comet moved towards and away from perihelion.&lt;/p&gt;&lt;p&gt;In this study, we focus on the changing role of chemistry during the escort phase, particularly on trends in the detection of high proton affinity species near perihelion and within the diamagnetic cavity. NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; is produced through the protonation of NH&lt;sub&gt;3&lt;/sub&gt; which has the highest proton affinity of the neutral species and is therefore the terminal ion. The ratio of this species to the major ion species H&lt;sub&gt;3&lt;/sub&gt;O&lt;sup&gt;+&lt;/sup&gt; can then be an indicator of the importance of ion-neutral chemistry as an ion loss process compared to transport. We use data from the high resolution mode of the ROSINA (Rosetta Orbital Spectrometer for Ion-Neutral Analysis)/DFMS (Double Focussing Mass Spectrometer) instrument, which allows certain ions of the
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Journal articleHalekas JS, Whittlesey P, Larson DE, et al., 2022,
The Radial Evolution of the Solar Wind as Organized by Electron Distribution Parameters
, ASTROPHYSICAL JOURNAL, Vol: 936, ISSN: 0004-637X- Author Web Link
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- Citations: 9
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Journal articleMalaspina DM, Chasapis A, Tatum P, et al., 2022,
Inhomogeneous Kinetic Alfven Waves in the Near-Sun Solar Wind
, ASTROPHYSICAL JOURNAL, Vol: 936, ISSN: 0004-637X- Author Web Link
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- Citations: 1
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Journal articleTigik SF, Vaivads A, Malaspina DM, et al., 2022,
Parker Solar Probe Observations of Near-<i>f</i> <sub>Ce</sub> Harmonic Emissions in the Near-Sun Solar Wind and Their Dependence on the Magnetic Field Direction
, ASTROPHYSICAL JOURNAL, Vol: 936, ISSN: 0004-637X- Author Web Link
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- Citations: 5
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Journal articleFranci L, Papini E, Micera A, et al., 2022,
Anisotropic Electron Heating in Turbulence-driven Magnetic Reconnection in the Near-Sun Solar Wind
, ASTROPHYSICAL JOURNAL, Vol: 936, ISSN: 0004-637X -
Journal articleAizawa S, Persson M, Menez T, et al., 2022,
LatHyS global hybrid simulation of the BepiColombo second Venus flyby
, PLANETARY AND SPACE SCIENCE, Vol: 218, ISSN: 0032-0633- Author Web Link
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- Citations: 3
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Journal articleDing M, Pickering JC, 2022,
Comment on: "Hyperfine structure measurements of Co I and Co II with Fourier transform spectroscopy" by Fu et al. [JQSRT 2021, 107590]
, JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER, Vol: 288, ISSN: 0022-4073- Author Web Link
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- Citations: 3
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Journal articleFranci L, Papini E, Del Sarto D, et al., 2022,
Plasma Turbulence in the Near-Sun and Near-Earth Solar Wind: A Comparison via Observation-Driven 2D Hybrid Simulations
, UNIVERSE, Vol: 8- Author Web Link
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- Citations: 1
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Journal articleTeoh R, Schumann U, Gryspeerdt E, et al., 2022,
Aviation contrail climate effects in the North Atlantic from 2016 to 2021
, Atmospheric Chemistry and Physics, Vol: 22, Pages: 10919-10935, ISSN: 1680-7316Around 5 % of anthropogenic radiative forcing (RF) is attributed to aviation CO2 and non-CO2 impacts. This paper quantifies aviation emissions and contrail climate forcing in the North Atlantic, one of the world's busiest air traffic corridors, over 5 years. Between 2016 and 2019, growth in CO2 (+3.13 % yr−1) and nitrogen oxide emissions (+4.5 % yr−1) outpaced increases in flight distance (+3.05 % yr−1). Over the same period, the annual mean contrail cirrus net RF (204–280 mW m−2) showed significant inter-annual variability caused by variations in meteorology. Responses to COVID-19 caused significant reductions in flight distance travelled (−66 %), CO2 emissions (−71 %) and the contrail net RF (−66 %) compared with the prior 1-year period. Around 12 % of all flights in this region cause 80 % of the annual contrail energy forcing, and the factors associated with strongly warming/cooling contrails include seasonal changes in meteorology and radiation, time of day, background cloud fields, and engine-specific non-volatile particulate matter (nvPM) emissions. Strongly warming contrails in this region are generally formed in wintertime, close to the tropopause, between 15:00 and 04:00 UTC, and above low-level clouds. The most strongly cooling contrails occur in the spring, in the upper troposphere, between 06:00 and 15:00 UTC, and without lower-level clouds. Uncertainty in the contrail cirrus net RF (216–238 mW m−2) arising from meteorology in 2019 is smaller than the inter-annual variability. The contrail RF estimates are most sensitive to the humidity fields, followed by nvPM emissions and aircraft mass assumptions. This longitudinal evaluation of aviation contrail impacts contributes a quantified understanding of inter-annual variability and informs strategies for contrail mitigation.
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Journal articleWang S, Toumi R, 2022,
Author Correction: On the intensity decay of tropical cyclones before landfall.
, Sci Rep, Vol: 12 -
Journal articleVuorinen L, Vainio R, Hietala H, et al., 2022,
Monte Carlo simulations of electron acceleration at bow waves driven by fast jets in the Earth’s magnetosheath
, The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 934, Pages: 1-7, ISSN: 0004-637XThe shocked solar wind flows around the Earth’s magnetosphere in the magnetosheath downstreamof the Earth’s bow shock. Within this region, faster flows of plasma, called magnetosheath jets, arefrequently observed. These jets have been shown to sometimes exhibit supermagnetosonic speedsrelative to the magnetosheath flow and to develop bow waves or shocks of their own. Such jet-drivenbow waves have been observed to accelerate ions and electrons. We model electron acceleration bymagnetosheath jet-driven bow waves using test-particle Monte Carlo simulations. Our simulationssuggest that the energy increase of electrons with energies of a few hundred eV to 10 keV can beexplained by a collapsing magnetic trap forming between the bow wave and the magnetopause withshock drift acceleration at the moving bow wave. Our simulations allow us to estimate the efficiencyof acceleration as a function of different jet and magnetosheath parameters. Electron acceleration byjet-driven bow waves can increase the total acceleration in the parent shock environment, most likelyalso at shocks other than the Earth’s bow shock.
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Journal articleShi C, Panasenco O, Velli M, et al., 2022,
Patches of Magnetic Switchbacks and Their Origins
, ASTROPHYSICAL JOURNAL, Vol: 934, ISSN: 0004-637X- Author Web Link
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- Citations: 9
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