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Observations of the First Harmonic of Saturn Kilometric Radiation During Cassini's Grand Finale
Lamy, Laurent; Fischer, Georg; Kurth, William S. +6 more
Clear first harmonic emissions of Saturn Kilometric Radiation are discovered during the Cassini Grand Finale orbits. Both ordinary (O) and extraordinary (X) mode fundamental emissions accompanied by X mode harmonics are observed. Analysis shows that the frequency ratio between the fundamental and harmonic emissions is 2.01 ± 0.08, and the harmonic…
Illuminating the Motions of Jupiter's Auroral Dawn Storms
Nichols, J. D.; Rutala, M. J.; Clarke, J. T. +1 more
Jupiter's auroral main emission (ME) has long been considered to be the result of currents keeping plasma corotating with the surrounding magnetosphere. As a result, the ME corotates with the planet, and individual auroral features making up the ME roughly follow suit. Jupiter's dawn storms, some of the rarest and brightest auroral features within…
Ion-Ion Cross-Field Instability of Lower Hybrid Waves in the Inner Coma of Comet 67P
Karlsson, Tomas; Stenberg Wieser, Gabriella; Odelstad, Elias +2 more
We show that an ion-ion cross-field streaming instability between cold newborn cometary ions and heated heavy ions that were picked up upstream is likely a contributing source of observed lower hybrid (LH) waves in the inner coma of comet 67P/Churyumov-Gerasimenko. Electric field oscillations in the LH frequency range are common here, and have pre…
Observations of a Solar Energetic Particle Event From Inside and Outside the Coma of Comet 67P
Coates, A. J.; Palmerio, E.; Jones, G. H. +12 more
We analyze observations of a solar energetic particle (SEP) event at Rosetta's target comet 67P/Churyumov-Gerasimenko during 6-10 March 2015. The comet was 2.15 AU from the Sun, with the Rosetta spacecraft approximately 70 km from the nucleus placing it deep inside the comet's coma and allowing us to study its response. The Eastern flank of an int…
The Response of Saturn's Dawn Field-Aligned Currents to Magnetospheric and Ring Current Conditions During Cassini's Proximal Orbits: Evidence for a Region 2 Response at Saturn
Dougherty, M. K.; Roussos, E.; Cowley, S. W. H. +3 more
Cassini's 2017 proximal orbits provided the opportunity to examine the auroral field-aligned currents in the northern hemisphere dawn sector in relation to wider magnetospheric conditions. We combine three recent studies to examine the response of the dawn region auroral field-aligned currents and the azimuthal ring currents to compressions and ex…
Mirror Mode Storms Observed by Solar Orbiter
Fedorov, A.; Karlsson, T.; Owen, C. J. +8 more
Mirror modes (MMs) are ubiquitous in space plasma and grow from pressure anisotropy. Together with other instabilities, they play a fundamental role in constraining the free energy contained in the plasma. This study focuses on MMs observed in the solar wind by Solar Orbiter (SolO) for heliocentric distances between 0.5 and 1 AU. Typically, MMs ha…
Poleward Moving Auroral Arcs and Pc5 Oscillations
Sato, N.; Tanaka, Y.; Ebihara, Y. +6 more
We present an example of one-to-one correspondence between poleward moving auroral arcs (PMAAs) and Pc5 oscillations observed at the Time History of Events and Macroscale Interactions during Substorms (THEMIS) Ground Based Observatory station Gillam. The PMAAs consisted of four successive intensifications (named PMAA1, PMAA2, PMAA3 and PMAA4) with…
Reply to Comment by Stauning on "The PC Index Variations During 23/24 Solar Cycles: Relation to Solar Wind Parameters and Magnetic Disturbances"
Sormakov, D. A.; Troshichev, O. A.; Dolgacheva, S. A. +1 more
The polar cap magnetic activity index (PC) was approved by IAGA as an index characterizing the solar wind energy input into the magnetosphere. Relation of the PC index to solar wind parameters and solar activity during 23/24 solar cycles has been studied in paper (Troshichev et al., 2021, https://doi.…
Joint Cluster/Ground-Based Studies in the First 20 Years of the Cluster Mission
Fear, R. C.
Ground-based facilities make an important contribution to our understanding of the magnetospheric system. Coordination with ground-based facilities has been embedded within the Cluster mission since before launch, and this has given rise to a large number of studies which have exploited data from both Cluster and one or more of the diverse range o…
Magnetosheath Filamentary Structures Driven by Foreshock Energetic Ions
Wei, Xinhua; Ma, Yuduan; Yang, Junying +1 more
Previous simulation studies have revealed the formation of magnetosheath filamentary structures by foreshock energetic ions. We report Cluster and Double Star observations of three such events triggered by a foreshock bubble, a hot flow anomaly and a traveling foreshock, respectively. In each case, in association with the onset of foreshock energe…