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Journal articleLarosa A, Dudok de Wit T, Krasnoselskikh V, et al., 2022,
Langmuir-Slow Extraordinary Mode Magnetic Signature Observations with Parker Solar Probe
, ASTROPHYSICAL JOURNAL, Vol: 927, ISSN: 0004-637X- Author Web Link
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- Citations: 4
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Journal articleMozer FS, Bale SD, Cattell CA, et al., 2022,
Core Electron Heating by Triggered Ion Acoustic Waves in the Solar Wind
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 927, ISSN: 2041-8205- Author Web Link
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- Citations: 4
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Journal articleDesai M, Mitchell DG, McComas DJ, et al., 2022,
Suprathermal ion energy spectra and anisotropies near the heliospheric current sheet crossing observed by the Parker Solar Probe during encounter 7
, The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 927, Pages: 1-12, ISSN: 0004-637XWe present observations of ≳10–100 keV nucleon−1 suprathermal (ST) H, He, O, and Fe ions associated with crossings of the heliospheric current sheet (HCS) at radial distances of <0.1 au from the Sun. Our key findings are as follows: (1) very few heavy ions are detected during the first full crossing, the heavy-ion intensities are reduced during the second partial crossing and peak just after the second crossing; (2) ion arrival times exhibit no velocity dispersion; (3) He pitch-angle distributions track the magnetic field polarity reversal and show up to ∼10:1 anti-sunward, field-aligned flows and beams closer to the HCS that become nearly isotropic farther from the HCS; (4) the He spectrum steepens either side of the HCS, and the He, O, and Fe spectra exhibit power laws of the form ∼E−4–E6; and (5) maximum energies EX increase with the ion's charge-to-mass (Q/M) ratio as ${E}_{X}/{E}_{H}\propto {({Q}_{X}/{M}_{X})}^{\delta }$, where δ ∼ 0.65–0.76, assuming that the average Q states are similar to those measured in gradual and impulsive solar energetic particle events at 1 au. The absence of velocity dispersion in combination with strong field-aligned anisotropies closer to the HCS appears to rule out solar flares and near-Sun coronal-mass-ejection-driven shocks. These new observations present challenges not only for mechanisms that employ direct parallel electric fields and organize maximum energies according to E/Q but also for local diffusive and magnetic-reconnection-driven acceleration models. Reevaluation of our current understanding of the production and transport of energetic ions is necessary to understand this near-solar, current-sheet-associated population of ST ions.
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Journal articleWang S, Toumi R, 2022,
On the intensity decay of tropical cyclones before landfall
, Scientific Reports, Vol: 12, ISSN: 2045-2322It remains unclear how tropical cyclones (TCs) decay from their ocean lifetime maximum intensity (LMI) to landfall intensity (LI), yet this stage is of fundamental importance governing the socio-economic impact of TCs. Here we show that TCs decay on average by 25% from LMI to LI. A logistic decay model of energy production by ocean enthalpy input and surface dissipation by frictional drag, can physically connect the LMI to LI. The logistic model fits the observed intensity decay as well as an empirically exponential decay does, but with a clear physical foundation. The distance between locations of LMI and TC landfall is found to dominate the variability of the decay from the LMI to LI, whereas environmental conditions are generally less important. A major TC at landfall typically has a very large LMI close to land. The LMI depends on the heating by ocean warming, but the LMI location is also important to future landfall TC intensity changes which are of socio-economic importance.
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Journal articleTrofimov H, Post P, Gryspeerdt E, et al., 2022,
Meteorological conditions favorable for strong anthropogenic aerosol impacts on clouds
, Journal of Geophysical Research: Atmospheres, Vol: 127, ISSN: 2169-897XShip-track-like polluted cloud tracks provide a direct way to study aerosol-cloud interactions. Here, we study environmental conditions favorable for pollution tracks' formation. We study polluted cloud tracks forming downwind of localized anthropogenic air pollution hot spots of Norilsk and Cherepovets in Russia and Thompson in Canada. Polluted cloud tracks form on 20%–37% of days with liquid-phase clouds. The large-scale atmospheric circulation largely determines the occurrence of track-favoring conditions. Tracks tend to form in clean and thin clouds under stable and dry conditions that are more often associated with anticyclonic large-scale flow in the studied locations.
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Journal articleChen L-J, Halekas J, Wang S, et al., 2022,
Solitary Magnetic Structures Developed From Gyro-Resonance With Solar Wind Ions at Mars and Earth
, GEOPHYSICAL RESEARCH LETTERS, Vol: 49, ISSN: 0094-8276- Author Web Link
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- Citations: 2
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Journal articleTinoco-Arenas A, Kajdic P, Preisser L, et al., 2022,
Parametric Study of Magnetosheath Jets in 2D Local Hybrid Simulations
, FRONTIERS IN ASTRONOMY AND SPACE SCIENCES, Vol: 9, ISSN: 2296-987X- Author Web Link
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- Citations: 3
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Journal articleMozer FS, Bale SD, Kellogg PJ, et al., 2022,
An Improved Technique for Measuring Plasma Density to High Frequencies on the Parker Solar Probe
, ASTROPHYSICAL JOURNAL, Vol: 926, ISSN: 0004-637X- Author Web Link
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- Citations: 1
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Journal articleRodriguez L, Barnes D, Hosteaux S, et al., 2022,
Comparing the heliospheric cataloging, analysis, and techniques service (HELCATS) manual and automatic catalogues of coronal mass ejections using solar terrestrial relations observatory/heliospheric Imager (STEREO/HI) Data
, Solar Physics: a journal for solar and solar-stellar research and the study of solar terrestrial physics, Vol: 297, ISSN: 0038-0938We present the results of a comparative study between automatic and manually compiled coronal mass ejection (CME) catalogues based on observations from the Heliospheric Imagers (HIs) onboard NASA’s Solar Terrestrial Relations Observatory (STEREO) spacecraft. Using the Computer Aided CME Tracking software (CACTus), CMEs are identified in HI data using an automatic feature-detection algorithm, while the Heliospheric Imagers Catalogue (HICAT) includes CMEs that are detected by visual inspection of HI images. Both catalogues were compiled as part of the EU FP7 Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project (www.helcats-fp7.eu). We compare observational parameters of the CMEs from CACTus to those listed in HICAT, such as CME frequency, position angle (PA), and PA-width. We also compare CACTus-derived speeds to speeds derived from applying geometric modelling to the majority of the HICAT CMEs, the results of which are listed in the HELCATS Heliospheric Imagers Geometric Catalogue (HIGeoCAT). We find that both CACTus and HICAT catalogues contain a similar number of events when we exclude events narrower than 20∘, which are not included in the HICAT catalogue but are found to be identified by CACTus. PA-distributions are strongly peaked around 90∘ and 270∘, with a slightly larger CME frequency northwards of the equatorial plane (particularly for the STEREO-A versions of both catalogues). The CME PA-widths in both HICAT and CACTus catalogues peak at approximately 60∘. Manually derived speeds from HIGeoCAT and automatically derived speeds by CACTus correlate well for values lower than 1000 km s−1, in particular when CMEs are propagating close to the plane of the sky.
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Journal articleShi C, Zhao J, Malaspina DM, et al., 2022,
Multiband Electrostatic Waves below and above the Electron Cyclotron Frequency in the Near-Sun Solar Wind
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205- Author Web Link
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- Citations: 4
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Journal articleVasko IY, Alimov K, Phan T, et al., 2022,
Kinetic-scale Current Sheets in the Solar Wind at 1 au: Scale-dependent Properties and Critical Current Density
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205- Author Web Link
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- Citations: 9
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Journal articleZank GP, Zhao L-L, Adhikari L, et al., 2022,
Turbulence in the Sub-Alfvenic Solar Wind
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205- Author Web Link
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- Citations: 26
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Journal articleMostafavi P, Allen RC, McManus MD, et al., 2022,
Alpha-Proton Differential Flow of the Young Solar Wind: Parker Solar Probe Observations
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205- Author Web Link
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- Citations: 6
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Journal articlevan der Holst B, Huang J, Sachdeva N, et al., 2022,
Improving the Alfven Wave Solar Atmosphere Model Based on Parker Solar Probe Data
, ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X- Author Web Link
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- Citations: 12
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Journal articleBandyopadhyay R, Matthaeus WH, McComas DJ, et al., 2022,
Sub-Alfvenic Solar Wind Observed by the Parker Solar Probe: Characterization of Turbulence, Anisotropy, Intermittency, and Switchback
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205- Author Web Link
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- Citations: 21
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Journal articleGetachew T, McComas DJ, Joyce CJ, et al., 2022,
PSP/IS⊙IS Observation of a Solar Energetic Particle Event Associated with a Streamer Blowout Coronal Mass Ejection during Encounter 6
, ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X- Author Web Link
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- Citations: 2
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Journal articleArcher M, Southwood D, Hartinger M, et al., 2022,
How a realistic magnetosphere alters the polarizations of surface, fast magnetosonic, and Alfvén waves
, Journal of Geophysical Research: Space Physics, Vol: 127, ISSN: 2169-9380System-scale magnetohydrodynamic (MHD) waves within Earth's magnetosphere are often understood theoretically using box models. While these have been highly instructive in understanding many fundamental features of the various wave modes present, they neglect the complexities of geospace such as the inhomogeneities and curvilinear geometries present. Here, we show global MHD simulations of resonant waves impulsively excited by a solar wind pressure pulse. Although many aspects of the surface, fast magnetosonic (cavity/waveguide), and Alfvén modes present agree with the box and axially symmetric dipole models, we find some predictions for large-scale waves are significantly altered in a realistic magnetosphere. The radial ordering of fast mode turning points and Alfvén resonant locations may be reversed even with monotonic wave speeds. Additional nodes along field lines that are not present in the displacement/velocity occur in both the perpendicular and compressional components of the magnetic field. Close to the magnetopause, the perpendicular oscillations of the magnetic field have the opposite handedness to the velocity. Finally, widely used detection techniques for standing waves, both across and along the field, can fail to identify their presence. We explain how all these features arise from the MHD equations when accounting for a non-uniform background field and propose modified methods that might be applied to spacecraft observations.
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Journal articleAgapitov V, Drake JF, Swisdak M, et al., 2022,
Flux Rope Merging and the Structure of Switchbacks in the Solar Wind
, ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X- Author Web Link
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- Citations: 9
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Journal articleLario D, Richardson IG, Wilson III LB, et al., 2022,
The Extended Field-aligned Suprathermal Proton Beam and Long-lasting Trapped Energetic Particle Population Observed Upstream of a Transient Interplanetary Shock
, ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X- Author Web Link
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- Citations: 2
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Journal articleShebanits O, Wahlund J-E, Waite JH, et al., 2022,
Conductivities of Titan's Dusty Ionosphere
, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 127, ISSN: 2169-9380- Author Web Link
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- Citations: 1
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Journal articleSimon Wedlund CL, Volwerk M, Beth A, et al., 2021,
A fast bow shock location predictor-estimator from 2D and 3D analytical models: Application to Mars and the MAVEN mission
, Journal of Geophysical Research: Space Physics, ISSN: 2169-9380 -
Journal articleArcher M, Waters C, Dewan S, et al., 2022,
GC Insights: Space sector careers resources need a greater diversity of roles
<jats:p>Abstract. Educational research highlights that improved careers education is needed to increase participation in STEM. Current careers resources concerning the space sector, however, are found to perhaps not best reflect the diversity of roles present and may in fact perpetuate misconceptions about the usefulness of science. We, therefore, compile a more diverse set of space-related jobs, which will be used in the development of a new space careers resource. </jats:p>
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Journal articleChristensen MW, Gettelman A, Cermak J, et al., 2022,
Opportunistic experiments to constrain aerosol effective radiative forcing
, Atmospheric Chemistry and Physics, Vol: 22, Pages: 641-674, ISSN: 1680-7316Aerosol–cloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due to human activities. The nonlinearity of cloud-state changes to aerosol perturbations make it challenging to attribute causality in observed relationships of aerosol radiative forcing. Using correlations to infer causality can be challenging when meteorological variability also drives both aerosol and cloud changes independently. Natural and anthropogenic aerosol perturbations from well-defined sources provide “opportunistic experiments” (also known as natural experiments) to investigate ACI in cases where causality may be more confidently inferred. These perturbations cover a wide range of locations and spatiotemporal scales, including point sources such as volcanic eruptions or industrial sources, plumes from biomass burning or forest fires, and tracks from individual ships or shipping corridors. We review the different experimental conditions and conduct a synthesis of the available satellite datasets and field campaigns to place these opportunistic experiments on a common footing, facilitating new insights and a clearer understanding of key uncertainties in aerosol radiative forcing. Cloud albedo perturbations are strongly sensitive to background meteorological conditions. Strong liquid water path increases due to aerosol perturbations are largely ruled out by averaging across experiments. Opportunistic experiments have significantly improved process-level understanding of ACI, but it remains unclear how reliably the relationships found can be scaled to the global level, thus demonstrating a need for deeper investigation in order to improve assessments of aerosol radiative forcing and climate change.
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Journal articleChadney JM, Koskinen TT, Hu X, et al., 2022,
Energy deposition in Saturn's equatorial upper atmosphere
, Icarus, Vol: 372, Pages: 1-16, ISSN: 0019-1035We construct Saturn equatorial neutral temperature and density profiles of H, H2, He, and CH4, between 10−12 and 1 bar using measurements from Cassini’s Ion Neutral Mass Spectrometer (INMS) taken during the spacecraft’s final plunge into Saturn’s atmosphere on 15 September 2017, combined with previous deeper atmospheric measurements from the Cassini Composite InfraRed Spectrometer (CIRS) and from the UltraViolet Imaging Spectrograph (UVIS). These neutral profiles are fed into an energy deposition model employing soft X-ray and Extreme UltraViolet (EUV) solar fluxes at a range of spectral resolutions (∆λ = 4×10−3 nm to 1 nm) assembled from TIMED/SEE, from SOHO/SUMER, and from the Whole Heliosphere Interval (WHI) quiet Sun campaign. Our energy deposition model calculates ion production rate profiles through photo-ionisation and electron-impact ionisation processes, as well as rates of photo-dissociation of CH4. The ion reaction rate profiles we determine are important to obtain accurate ion density profiles, meanwhile methane photo-dissociation is key to initiate complex organic chemical processes. We assess the importance of spectral resolution in the energy deposition model by using a high-resolution H2 photo-absorption cross section, which has the effect of producing additional ionisation peaks near 800 km altitude. We find that these peaks are still formed when using low resolution (∆λ = 1 nm) or mid-resolution (∆λ = 0.1 nm) solar spectra, as long as high-resolution cross sections are included in the model.
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Journal articleStawarz J, Eastwood J, Phan T, et al., 2022,
Turbulence-driven magnetic reconnection and the magnetic correlation length: observations from magnetospheric multiscale in Earth's magnetosheath
, Physics of Plasmas, Vol: 29, Pages: 1-20, ISSN: 1070-664XTurbulent plasmas generate a multitude of thin current structures that can be sites for magnetic reconnection. The Magnetospheric Multiscale (MMS) mission has recently enabled the detailed examination of such turbulent current structures in Earth's magnetosheath and revealed that a novel type of reconnection, known as electron-only reconnection, can occur. In electron-only reconnection, ions do not have enough space to couple to the newly reconnected magnetic fields, suppressing ion jet formation and resulting in thinner sub-proton-scale current structures with faster super-Alfvénic electron jets. In this study, MMS observations are used to examine how the magnetic correlation length (λC) of the turbulence, which characterizes the size of the large-scale magnetic structures and constrains the length of the current sheets formed, influences the nature of turbulence-driven reconnection. We systematically identify 256 reconnection events across 60 intervals of magnetosheath turbulence. Most events do not appear to have ion jets; however, 18 events are identified with ion jets that are at least partially coupled to the reconnected magnetic field. The current sheet thickness and electron jet speed have a weak anti-correlation, with faster electron jets at thinner current sheets. When 𝜆𝐶≲20 ion inertial lengths, as is typical near the sub-solar magnetosheath, a tendency for thinner current sheets and potentially faster electron jets is present. The results are consistent with electron-only reconnection being more prevalent for turbulent plasmas with relatively short λC and may be relevant to the nonlinear dynamics and energy dissipation in turbulent plasmas.
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Conference paperAngelini V, O'Brien H, Horbury T, et al., 2022,
Novel magnetic cleaning techniques for Solar Orbiter magnetometer
Solar Orbiter is an ESA mission studying the heliosphere and the Sun. The magnetometer is designed to measure the magnetic field local to the spacecraft and is composed of two sensors located on a boom at different displacement from the spacecraft. This configuration reduces the electromagnetic interference caused by other on-board electrical systems and allows the exploitation of the 'gradiometer technique' to separate spacecraft generated signals from the solar magnetic field. This paper describes the analysis of the magnetometer data to develop a completely novel procedure for removing the magnetic field generated by the spacecraft-controlled heaters, the instruments, and the thrusters on the spacecraft. The difference between the data measured by the two sensors is used to identify this signal, which is then appropriately scaled and removed from the data. This approach produces cleaned magnetic field data which is routinely uploaded to the Solar Orbiter Archive for science exploitation.
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Conference paperEckersley S, Rowe S, Antoniou N, et al., 2022,
A Distributed Space-Weather Sensor System using Small Satellites
, ISSN: 0074-1795Space weather is becoming increasingly important for space and terrestrial activities and is likely to transition to an operational service. Small satellites are ideally suited for space-weather measurements given the need for making simultaneous measurements across both small and large volumes of space. The “Nanosatellites for D3S” Phase 0/A study for ESA was initiated in early 2021 with the objective to assess the feasibility of using nanosatellites for future operational space weather monitoring missions in near-Earth space as part of ESA's Distributed Space Weather Sensor System (D3S) - which itself forms part of the wider ESA Enhanced Space Weather Monitoring System. The study team consortium is highly experienced including sub-contractors supporting SSTL from MSSL, Imperial College London, and VZLU. Surrey Space Centre and Northumbria University are also providing expert consultancy. In the first part of the Phase 0 study, a survey of the measurement requirements and potential space weather instruments was carried out, alongside an investigation into recent relevant nanosatellite missions and future nanosatellite technologies. This was followed by an analysis and trade-off of high level mission architecture concepts eventually converging down to two of the most promising mission architecture concepts, which were further analysed in the latter half of the Phase 0 study. The objective of the first Phase 0 mission architecture concept was to provide near-real time measurements of radiation, thermal plasma and Ionospheric neutrals/plasma, via a constellation of 20x SSTL-21 satellites, in a single LEO orbital plane. The objective of the second Phase 0 mission architecture concept was to provide near-real time measurements of radiation, the Ionosphere and the Thermosphere, via a constellation of 6x 16U SSTL-Cube satellites, in a single LEO orbital plane. The orbit selected for both missions was a 500-600km Sun-Synchronous LEO Orbit with an LTAN of 10:30a
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Journal articleVerniero JL, Chandran BDG, Larson DE, et al., 2022,
Strong Perpendicular Velocity-space Diffusion in Proton Beams Observed by Parker Solar Probe
, ASTROPHYSICAL JOURNAL, Vol: 924, ISSN: 0004-637X- Author Web Link
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- Citations: 9
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Journal articleMalaspina DM, Stenborg G, Mehoke D, et al., 2022,
Clouds of Spacecraft Debris Liberated by Hypervelocity Dust Impacts on Parker Solar Probe
, ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X- Author Web Link
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- Citations: 6
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Journal articleCattell C, Breneman A, Dombeck J, et al., 2022,
Parker Solar Probe Evidence for the Absence of Whistlers Close to the Sun to Scatter Strahl and to Regulate Heat Flux
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 924, ISSN: 2041-8205- Author Web Link
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- Citations: 17
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