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Models of Saturn's Equatorial Ionosphere Based on In Situ Data From Cassini's Grand Finale
Wahlund, J. -E.; Waite, J. H.; Cravens, T. E. +8 more
We present new models of Saturn's equatorial ionosphere based on the first in situ measurements of its upper atmosphere. The neutral spectrum measured by Cassini's Ion and Neutral Mass Spectrometer, which includes substantial methane, ammonia, and organics in addition to the anticipated molecular hydrogen, helium, and water, serves as input for un…
Intense Current Structures Observed at Electron Kinetic Scales in the Near-Earth Magnetotail During Dipolarization and Substorm Current Wedge Formation
Lavraud, B.; Malykhin, A. Yu.; Grigorenko, E. E. +4 more
We use data from the 2013-2014 Cluster Inner Magnetosphere Campaign, with its uniquely small spacecraft separations (less than or equal to electron inertia length, <fi>λ</fi>e), to study multiscale magnetic structures in 14 substorm-related prolonged dipolarizations in the near-Earth magnetotail. Three time scales of dipolar…
Responses of the Martian Magnetosphere to an Interplanetary Coronal Mass Ejection: MAVEN Observations and LatHyS Results
Holmström, M.; Luhmann, J. G.; Chaufray, J. -Y. +12 more
The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft observed a strong interplanetary coronal mass ejection (ICME) reaching Mars on 13 September 2017. In this work we analyze the interaction between such an extreme event and the Martian-induced magnetosphere by means of Laboratoire Atmosphères, Milieux et Observations Spatiales Hybrid Sim…
Electron Distributions in Kinetic Scale Field Line Resonances: A Comparison of Simulations and Observations
Hull, A. J.; Chaston, C. C.; Johnson, J. R. +1 more
Observations in kinetic scale field line resonances, or eigenmodes of the geomagnetic field, reveal highly field-aligned plateaued electron distributions. By combining observations from the Van Allen Probes and Cluster spacecraft with a hybrid kinetic gyrofluid simulation we show how these distributions arise from the nonlocal self-consistent inte…
Thermal Structure and Composition of Saturn's Upper Atmosphere From Cassini/Ion Neutral Mass Spectrometer Measurements
Waite, J. Hunter; Hörst, S. M.; Perry, M. E. +4 more
Analysis of measurements of the H2 density in Saturn's equatorial thermosphere indicates temperatures from 340 to 370 K. The deepest measurements, obtained during Cassini's final plunge into the atmosphere, measure the thermospheric temperature profile. The measurements are well fit by a Bates profile with an exospheric temperature of 3…
The September 2017 SEP Event in Context With the Current Solar Cycle: Mars Express ASPERA-3/IMA and MAVEN/SEP Observations
Holmström, Mats; Futaana, Yoshifumi; Ramstad, Robin +5 more
We use Mars Atmosphere and Volatile Evolution/Solar Energetic Particle (MAVEN/SEP) data to estimate the ranges of particle energies that generate background noise in the Analyzer of Space Plasmas and Energetic Atoms-3/Ion Mass Analyzer (IMA) instrument on Mars Express. The particles that generate IMA background counts are estimated to be electrons…
Ion Acceleration by Flux Transfer Events in the Terrestrial Magnetosheath
Vainio, R.; Palmroth, M.; Turc, L. +6 more
We report ion acceleration by flux transfer events in the terrestrial magnetosheath in a global two-dimensional hybrid-Vlasov polar plane simulation of Earth's solar wind interaction. In the model we find that propagating flux transfer events created in magnetic reconnection at the dayside magnetopause drive fast-mode bow waves in the magnetosheat…
Circulation of Venusian Atmosphere at 90-110 km Based on Apparent Motions of the O2 1.27 µm Nightglow From VIRTIS-M (Venus Express) Data
Piccioni, G.; Zasova, L. V.; Khatuntsev, I. V. +2 more
The paper is devoted to the investigation of Venus mesosphere circulation at 90-110 km altitudes, where tracking of the O2(a1Δg) 1.27 µm nightglow is practically the only method of studying the circulation. The images of the nightglow were obtained by VIRTIS-M on Venus Express over the course of more than 2 y…
An Empirical Model of the Variation of the Solar Lyman-α Spectral Irradiance
Kretzschmar, Matthieu; Curdt, Werner; Snow, Martin
We propose a simple model that computes the spectral profile of the solar irradiance in the hydrogen Lyman alpha line, H Ly-α (121.567 nm), from 1947 to present. Such a model is relevant for the study of many astronomical environments, from planetary atmospheres to interplanetary medium. This empirical model is based on the SOlar Heliospheric Obse…
The Oxygen Ion Circulation in The Outer Terrestrial Magnetosphere and Its Dependence on Geomagnetic Activity
Nilsson, H.; Slapak, R.
We have quantified the O+ transports in the plasma sheet and lobes (-20 < XGSM<-10RE) and their dependencies on geomagnetic activity, Kp, using Cluster data. We found that they have similar behavior as the polar region O+ outflow as well as the O+ fluxes in the plasma mantle and high-lat…