scholarly journals Dual-lobe reconnection and cusp-aligned auroral arcs

2021 ◽  
Author(s):  
Stephen E. Milan ◽  
Gemma E. Bower ◽  
Jennifer Alyson Carter ◽  
Larry J. Paxton ◽  
Brian J. Anderson ◽  
...  
Keyword(s):  
Auroral Arcs ◽  
Lobe Reconnection

scholarly journals Interplanetary magnetic field control of Saturn's polar cusp aurora

2005 ◽  
Vol 23 (4) ◽  
pp. 1405-1431 ◽  
Author(s):  
E. J. Bunce ◽  
S. W. H. Cowley ◽  
S. E. Milan
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Interplanetary Magnetic Field ◽  
Field Line ◽  
High Latitude ◽  
Closed Field ◽  
Vortical Flows ◽  
Dayside Magnetopause ◽  
Closed Field Line ◽  
Lobe Reconnection

Abstract. Dayside UV emissions in Saturn's polar ionosphere have been suggested to be the first observational evidence of the kronian "cusp" (Gérard et al., 2004). The emission has two distinct states. The first is a bright arc-like feature located in the pre-noon sector, and the second is a more diffuse "spot" of aurora which lies poleward of the general location of the main auroral oval, which may be related to different upstream interplanetary magnetic field (IMF) orientations. Here we take up the suggestion that these emissions correspond to the cusp. However, direct precipitation of electrons in the cusp regions is not capable of producing significant UV aurora. We have therefore investigated the possibility that the observed UV emissions are associated with reconnection occurring at the dayside magnetopause, possibly pulsed, akin to flux transfer events seen at the Earth. We devise a conceptual model of pulsed reconnection at the low-latitude dayside magnetopause for the case of northwards IMF which will give rise to pulsed twin-vortical flows in the magnetosphere and ionosphere in the vicinity of the open-closed field-line boundary, and hence to bi-polar field-aligned currents centred in the vortical flows. During intervals of high-latitude lobe reconnection for southward IMF, we also expect to have pulsed twin-vortical flows and corresponding bi-polar field-aligned currents. The vortical flows in this case, however, are displaced poleward of the open-closed field line boundary, and are reversed in sense, such that the field-aligned currents are also reversed. For both cases of northward and southward IMF we have also for the first time included the effects associated with the IMF By effect. We also include the modulation introduced by the structured nature of the solar wind and IMF at Saturn's orbit by developing "slow" and "fast" flow models corresponding to intermediate and high strength IMF respectively. We then consider the conditions under which the plasma populations appropriate to either sub-solar reconnection or high-latitude lobe reconnection can carry the currents indicated. We have estimated the field-aligned voltages required, the resulting precipitating particle energy fluxes, and the consequent auroral output. Overall our model of pulsed reconnection under conditions of northwards and southwards IMF, and for varying orientations of IMF By, is found to produce a range of UV emission intensities and geometries which is in good agreement with the data presented by Gérard et al. (2004). The recent HST-Cassini solar wind campaign provides a unique opportunity to test the theoretical ideas presented here.

scholarly journals Dual‐Lobe Reconnection and Horse‐Collar Auroras

2020 ◽  
Vol 125 (10) ◽  
Author(s):  
S. E. Milan ◽  
J. A. Carter ◽  
G. E. Bower ◽  
S. M. Imber ◽  
L. J. Paxton ◽  
...  
Keyword(s):  
Lobe Reconnection

scholarly journals Dual-lobe reconnection and horse-collar auroras

2020 ◽  
Author(s):  
Stephen E. Milan ◽  
Jennifer Alyson Carter ◽  
Gemma E. Bower ◽  
Suzanne Mary Imber ◽  
Larry J. Paxton ◽  
...  
Keyword(s):  
Lobe Reconnection

scholarly journals Spectral observations of FUV auroral arcs and comparison with inverted-V precipitating electrons

2010 ◽  
Vol 115 (A9) ◽  
pp. n/a-n/a ◽  
Author(s):  
C. N. Lee ◽  
K. W. Min ◽  
J.-J. Lee ◽  
G. K. Parks ◽  
M. O. Fillingim ◽  
...  
Keyword(s):  
Auroral Arcs

Relation of substorm breakup arc to other growth-phase auroral arcs

2002 ◽  
Vol 107 (A11) ◽  
Author(s):  
L. R. Lyons
Keyword(s):  
Growth Phase ◽  
Auroral Arcs

scholarly journals Dawn Auroral Breakup at Saturn Initiated by Auroral Arcs: UVIS/Cassini Beginning of Grand Finale Phase

2017 ◽  
Vol 122 (12) ◽  
pp. 12,111-12,119 ◽  
Author(s):  
A. Radioti ◽  
D. Grodent ◽  
Z. H. Yao ◽  
J.-C. Gérard ◽  
S. V. Badman ◽  
...  
Keyword(s):  
Auroral Breakup ◽  
Auroral Arcs

scholarly journals Species dependent energies in upward directed ion beams over auroral arcs as observed with FAST TEAMS

1998 ◽  
Vol 25 (12) ◽  
pp. 2029-2032 ◽  
Author(s):  
E. Möbius ◽  
L. Tang ◽  
L. M. Kistler ◽  
M. Popecki ◽  
E. J. Lund ◽  
...  
Keyword(s):  
Ion Beams ◽  
Auroral Arcs

Midlatitude Auroral Arcs of 6300 Å (O I) and the Concurrent Ionospheric Current System

Radio Science ◽  
1971 ◽  
Vol 6 (10) ◽  
pp. 887-891 ◽  
Author(s):  
M. Okuda ◽  
T. Old ◽  
J. S. Kim
Keyword(s):  
Current System ◽  
Ionospheric Current ◽  
Ionospheric Current System ◽  
Auroral Arcs

Self-excitation of auroral arcs in a three-dimensionally coupled magnetosphere-ionosphere system

1988 ◽  
Vol 15 (7) ◽  
pp. 717-720 ◽  
Author(s):  
Kunihiko Watanabe ◽  
Tetsuya Sato
Keyword(s):  
Auroral Arcs
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