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Subion-Scale Flux Rope Nested Inside Ion-Scale Flux Rope in Earth's Magnetotail
DOI: 10.1029/2021GL096169 Bibcode: 2021GeoRL..4896169H

Wang, Z.; Liu, Y. Y.; Fu, H. S. +2 more

Magnetic flux ropes (MFRs)—transient magnetic structures widely observed in Earth's magnetosphere—play crucial roles in particle acceleration and energy dissipation. MFRs above ion scale have been well studied, while MFRs at subion scales and their coupling with larger-scale ropes still remains not well understood. In this paper, we present the fi…

2021 Geophysical Research Letters
Cluster 5
Double Peak Structures of Martian Nightside Total Electron Content in Strong Crustal Magnetic Cusp Regions
DOI: 10.1029/2021GL092662 Bibcode: 2021GeoRL..4892662Q

Futaana, Yoshifumi; Nielsen, Erling; Qin, JunFeng +4 more

With the help of the high spatial resolution total electron content (TEC) data obtained by Mars Advanced Radar for Subsurface and Ionospheric Sounding on board the Mars Express (MEx) during June 2005 to September 2007, the detailed configurations of the Martian nightside ionosphere in crustal magnetic field cusp regions are researched in this pape…

2021 Geophysical Research Letters
MEx 5
The Statistical Morphology of Saturn's Equatorial Energetic Neutral Atom Emission
DOI: 10.1029/2020GL091595 Bibcode: 2021GeoRL..4891595K

Mitchell, D. G.; Paranicas, C.; Badman, S. V. +6 more

Saturn's magnetosphere is an efficient emitter of energetic neutral atoms (ENAs), created through charge exchange of energetic ions with the extended neutral cloud originating from the icy moon Enceladus. We present an analysis using the complete image set captured by Cassini's Ion Neutral Camera to characterize Saturn's average ENA morphology. Co…

2021 Geophysical Research Letters
Cassini 4
Was Gale Crater (Mars) Connected to a Regionally Extensive Groundwater System?
DOI: 10.1029/2020GL092107 Bibcode: 2021GeoRL..4892107R

Horvath, D. G.; Roseborough, V.; Palucis, M. C.

Gale crater, home of the Curiosity rover, contains some of the best geomorphic and sedimentologic evidence on Mars for large lakes during the Hesperian and Amazonian. Orbital data and rover observations of delta deposits and terminations of gully networks suggest several phases of stable lake levels. However, the regional extent, water source (gro…

2021 Geophysical Research Letters
MEx 4
On the Persistent Poloidal Alfven Waves
DOI: 10.1029/2021GL092945 Bibcode: 2021GeoRL..4892945C

Choi, Jiwon; Lee, Dong-Hun

Standing poloidal Alfven waves, radial oscillations with ultralow frequency of 5-20 mHz, are excited by wave-particle interaction in the magnetosphere. It has been a question over several decades why poloidal oscillations often persist and are not quickly converted into toroidal waves even when there is no corresponding particle source. By adoptin…

2021 Geophysical Research Letters
Cluster 3
Caldera Collapse and Volcanic Resurfacing in Arabia Terra Provide Hints of Vast Under-Recognized Early Martian Volcanism
DOI: 10.1029/2021GL093118 Bibcode: 2021GeoRL..4893118C

Michalski, Joseph R.; Wright, Shawn P.; Chu, Yin Yau Yoyo +1 more

Arabia Terra is an ancient, geologically complex region of Mars. It is not typically described as volcanic because it lacks prominent, easily recognizable shield volcanoes. However, Arabia Terra contains flood lavas and widespread layered materials that might represent airfall pyroclastics from unknown sources. Here we explore the geology of some …

2021 Geophysical Research Letters
MEx 3
Titan's Global Radiant Energy Budget During the Cassini Epoch (2004-2017)
DOI: 10.1029/2021GL095356 Bibcode: 2021GeoRL..4895356C

West, Robert A.; Nixon, Conor A.; Fry, Patrick M. +5 more

Radiant energies of planets and moons are of wide interest in the fields of geoscience and planetary science. Based on long-term multiinstrument observations from the Cassini spacecraft, we provide here the first observational study of Titan's global radiant energy budget and its seasonal variations. Our results show that Titan's radiant energy bu…

2021 Geophysical Research Letters
Cassini 3
Properties of Plasmoids Observed in Saturn's Dayside and Nightside Magnetodisc
DOI: 10.1029/2021GL096765 Bibcode: 2021GeoRL..4896765X

Coates, A. J.; Wei, Y.; Ye, S. -Y. +7 more

Plasmoid is a key structure for transferring magnetic flux and plasma in planetary magnetospheres. At Earth, plasmoids are key media which transfer energy and mass in the "Dungey Cycle." For giant planets, plasmoids are primarily generated by the dynamic processes associated with "Vasyliunas cycle." It is generally believed that planetary magnetot…

2021 Geophysical Research Letters
Cassini 3
The Micro-Macro Coupling of Mass-Loading in Symmetric Magnetic Reconnection With Cold Ions
DOI: 10.1029/2020GL090690 Bibcode: 2021GeoRL..4890690S

Hesse, Michael; Spinnangr, Susanne F.; Tenfjord, Paul +4 more

We investigate how magnetic reconnection is influenced by an inflow of a dense cold ion population. We compare two 2.5D Particle-In-Cell simulations, one containing the cold population and one without. We find that the cold population influences the reconnection process on both global and kinetic scales, and that the dominant contribution can be e…

2021 Geophysical Research Letters
Cluster 3
The Cushion Region and Dayside Magnetodisc Structure at Saturn
DOI: 10.1029/2020GL091796 Bibcode: 2021GeoRL..4891796S

Dougherty, M. K.; Masters, A.; Achilleos, N. +1 more

A sustained quasi dipolar magnetic field between the current sheet outer edge and the magnetopause, known as a cushion region, has previously been observed at Jupiter, but not yet at Saturn. Using the complete Cassini magnetometer data, the first evidence of a cushion region forming at Saturn is shown. Only five examples of a sustained cushion are…

2021 Geophysical Research Letters
Cassini 2