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:2018:10.1029/2017JA025067,
author = {Hunt, GJ and Provan, G and Bunce, EJ and Cowley, SWH and Dougherty, MK and Southwood, DJ},
doi = {10.1029/2017JA025067},
journal = {Journal of Geophysical Research: Space Physics},
pages = {3806--3821},
title = {Field-aligned currents in Saturn’s magnetosphere: Observations from the F-ring orbits},
url = {http://dx.doi.org/10.1029/2017JA025067},
volume = {123},
year = {2018}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We investigate the azimuthal magnetic field signatures associated with highlatitude fieldaligned currents observed during Cassini's Fring orbits (October 2016–April 2017). The overall ionospheric meridional current profiles in the northern and southern hemispheres, that is, the regions poleward and equatorward of the fieldaligned currents, differ most from the 2008 observations. We discuss these differences in terms of the seasonal change between data sets and local time (LT) differences, as the 2008 data cover the nightside while the Fring data cover the postdawn and dusk sectors in the northern and southern hemispheres, respectively. The Fring fieldaligned currents typically have a similar four current sheet structure to those in 2008. We investigate the properties of the current sheets and show that the fieldaligned currents in a hemisphere are modulated by that hemisphere's “planetary period oscillation” (PPO) systems. We separate the PPOindependent and PPOrelated currents in both hemispheres using their opposite symmetry. The average PPOindependent currents peak at ~1.5 MA/rad just equatorward of the open closed field line boundary, similar to the 2008 observations. However, the PPOrelated currents in both hemispheres are reduced by ~50% to ~0.4 MA/rad. This may be evidence of reduced PPO amplitudes, similar to the previously observed weaker equatorial oscillations at similar dayside LTs. We do not detect the PPO current systems' interhemispheric component, likely a result of the weaker PPOrelated currents and their closure within the magnetosphere. We also do not detect previously proposed lower latitude discrete fieldaligned currents that act to “turn off” the PPOs.
AU  - Hunt,GJ
AU  - Provan,G
AU  - Bunce,EJ
AU  - Cowley,SWH
AU  - Dougherty,MK
AU  - Southwood,DJ
DO  - 10.1029/2017JA025067
EP  - 3821
PY  - 2018///
SN  - 2169-9402
SP  - 3806
TI  - Field-aligned currents in Saturn’s magnetosphere: Observations from the F-ring orbits
T2  - Journal of Geophysical Research: Space Physics
UR  - http://dx.doi.org/10.1029/2017JA025067
UR  - http://hdl.handle.net/10044/1/59814
VL  - 123
ER  -
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