Imperial College London
Alternate

ProfessorMicheleDougherty

Faculty of Natural Sciences, Department of Physics

Head of Department of Physics, Professor of Space Physics
 
 
 
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Contact

 

+44 (0)20 7594 7770m.dougherty Website

 
 
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Assistant

 

Ms Lida Mnatsakanian +44 (0)20 7594 7503

 
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Location

 

Blackett 900aBlackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Hunt:2016:10.1002/2016JA022712,
author = {Hunt, GJ and Cowley, SWH and Provan, G and Bunce, EJ and Alexeev, II and Belenkaya, ES and Kalegaev, VV and Dougherty, MK and Coates, AJ},
doi = {10.1002/2016JA022712},
journal = {Journal of Geophysical Research: Space Physics},
pages = {7785--7804},
title = {Field-aligned currents in Saturn's magnetosphere: local time dependence of southern summer currents in the dawn sector between midnight and noon},
url = {http://dx.doi.org/10.1002/2016JA022712},
volume = {121},
year = {2016}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We examine and compare the magnetic field perturbations associated with field-aligned ionosphere-magnetosphere coupling currents at Saturn, observed by the Cassini spacecraft during two sequences of highly inclined orbits in 2006/2007 and 2008 under late southern summer conditions. These sequences explore the southern currents in the dawn-noon and midnight sectors, respectively, thus allowing investigation of possible origins of the local time (LT) asymmetry in auroral Saturn kilometric radiation (SKR) emissions, which peak in power at ~8 h LT in the dawn-noon sector. We first show that the dawn-noon field data generally have the same four-sheet current structure as found previously in the midnight data and that both are similarly modulated by “planetary period oscillation” (PPO) currents. We then separate the averaged PPO-independent (e.g., subcorotation) and PPO-related currents for both LT sectors by using the current system symmetry properties. Surprisingly, we find that the PPO-independent currents are essentially identical within uncertainties in the dawn-dusk and midnight sectors, thus providing no explanation for the LT dependence of the SKR emissions. The main PPO-related currents are, however, found to be slightly stronger and narrower in latitudinal width at dawn-noon than at midnight, leading to estimated precipitating electron powers, and hence emissions, that are on average a factor of ~1.3 larger at dawn-noon than at midnight, inadequate to account for the observed LT asymmetry in SKR power by a factor of ~2.7. Some other factors must also be involved, such as a LT asymmetry in the hot magnetospheric auroral source electron population.
AU  - Hunt,GJ
AU  - Cowley,SWH
AU  - Provan,G
AU  - Bunce,EJ
AU  - Alexeev,II
AU  - Belenkaya,ES
AU  - Kalegaev,VV
AU  - Dougherty,MK
AU  - Coates,AJ
DO  - 10.1002/2016JA022712
EP  - 7804
PY  - 2016///
SN  - 2169-9402
SP  - 7785
TI  - Field-aligned currents in Saturn's magnetosphere: local time dependence of southern summer currents in the dawn sector between midnight and noon
T2  - Journal of Geophysical Research: Space Physics
UR  - http://dx.doi.org/10.1002/2016JA022712
UR  - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000385811500033&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - http://hdl.handle.net/10044/1/43977
VL  - 121
ER  -
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