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Convective plumes and the scarcity of Titan's clouds
Lorenz, Ralph D.; McKay, Christopher P.; Griffith, Caitlin A. +2 more
We show that simple thermodynamic models of convective plumes predict the area fraction of convective plumes (i.e., updrafts) in Titan's atmosphere to be ~12 smaller than on Earth. This result is in agreement with predictions by sophisticated dynamical models and with the relative tropospheric cloud cover, which is only ~1% on Titan. Rainstorms on…
Preliminary results on Saturn's inner plasmasphere as observed by Cassini: Comparison with Voyager
Coates, A. J.; Crary, F.; Johnson, R. E. +12 more
We present an analysis of Saturn's inner plasmasphere as observed by the Cassini Plasma Spectrometer (CAPS) experiment during Cassini's initial entry into Saturn's magnetosphere when the spacecraft was inserted into orbit around Saturn. The ion fluxes are divided into two sub-groups: protons and water group ions. We present the relative amounts of…
Titan's stratospheric zonal wind, temperature, and ethane abundance a year prior to Huygens insertion
Sonnabend, G.; Kostiuk, T.; Murakawa, K. +7 more
Saturn's satellite, Titan, may have stratospheric winds up to ~210 m/s, circling Titan in ~1 terrestrial day compared to its 16-day rotation. Theoretical models explaining such super-rotating winds are not well constrained by observations of Titan or a similar slow rotator, Venus. We report measurements taken in December 2003 of zonal wind near Ti…
New features of electron diffusion regions observed at subsolar magnetic field reconnection sites
Bale, S. D.; Torbert, R. B.; McFadden, J. P. +1 more
Nineteen electron diffusion regions at magnetic field reconnection sites have been found in one hour of Cluster satellite data near the subsolar magnetopause. Investigations on previously unachieved spatial and temporal scales show the following for the first time: direct conversion of magnetic energy to electron energy (The resulting accelerated …
The global plasma environment of Titan as observed by Cassini Plasma Spectrometer during the first two close encounters with Titan
Coates, A. J.; Crary, F.; Johnson, R. E. +17 more
The Cassini spacecraft flew by Titan on October 26, 2004 and December 13, 2004. In both cases it entered the ionosphere of Titan, allowing exploration of its plasma environment. Using observations from the Cassini Plasma Spectrometer (CAPS) and the Cassini magnetometer along the inbound legs of both flybys, we examine Titan's global plasma environ…
Plasma electrons above Saturn's main rings: CAPS observations
Lewis, G. R.; Coates, A. J.; Tokar, R. L. +8 more
We present observations of thermal (~0.6-100eV) electrons observed near Saturn's main rings during Cassini's Saturn Orbit Insertion (SOI) on 1 July 2004. We find that the intensity of electrons is broadly anticorrelated with the ring optical depth at the magnetic footprint of the field line joining the spacecraft to the rings. We see enhancements …
Plasmoid in the high latitude boundary/cusp region observed by Cluster
Balogh, A.; Glassmeier, K. -H.; Zhang, H. +8 more
A plasmoid-like structure without a core magnetic field has been observed by Cluster spacecraft in the high latitude magnetopause region when the interplanetary magnetic field (IMF) is northward and has a dominant duskward component. Bursty electrons and ions are found to be well confined in this plasmoid-like structure. The structure possesses a …
On the formation of the high-altitude stagnant cusp: Cluster observations
Davies, J. A.; Wild, J. A.; Fazakerley, A. N. +7 more
On 16 March 2002, Cluster moved from nightside to dayside, across the high-altitude northern cusp during an extended period of relatively steady positive IMF BY and BZ. Combined Cluster and SuperDARN data imply the existence of two reconnection sites: in the high-latitude northern hemisphere dusk and southern hemisphere dawn …
Cluster observations of currents in the plasma sheet during reconnection
Balogh, A.; Fazakerley, A. N.; Klecker, B. +6 more
We present Cluster PEACE observations of parallel electron currents near a reversal of accelerated ion flows which indicated that the spacecraft were in the vicinity of an active reconnection X-line (XL). Moments calculated from the PEACE electron spectrometer 3D 4s resolution data are analysed. We surveyed the electron current structure to reveal…
A survey of flux transfer events observed by Cluster during strongly northward IMF
Fazakerley, A. N.; Owen, C. J.; Lucek, E. A. +1 more
During Cluster's annual dayside seasons (November-June) the four spacecraft cross the magnetopause at high latitudes near local noon, and at lower latitudes further along the flanks. During these crossings, observations of flux transfer events (FTEs), a signature of transient or variable-rate magnetopause merging, are often made. We have compiled …