Asset Details

  • Description:
  • Plots of Saturn inner field line regimes in a meridian plane in cylindrical (ρ, z) coordinates, where ρ is the perpendicular distance from the spin/magnetic axis and z is distance along the axis positive northward. The outer edge of the planetary body (orange spheroid) is taken to be the main conducting ionospheric layer 1,000 km above the 1‐bar reference spheroid, while the arrowed black lines show model field lines derived using the first three terms of the Dougherty et al. () planetary field model plus the Bunce et al. () ring current model for a typical subsolar magnetopause radius of 22 RS. The darker blue areas indicate field lines passing through the main ring region in the planet's equatorial plane (black dotted line), bounded by the field line passing through the outer boundary of the A ring. The lighter blue area corresponds to field lines passing through the innermost D ring. In Figure a, polar field lines have been drawn at 5° colatitude intervals from the southern pole between 0° and 30°, together with their northern conjugate counterparts, while the purple areas indicate the approximate conjugate locations of the main auroral field‐aligned currents in both hemispheres. Cassini trajectories for Revs 287 (blue) and 288 (red) are shown projected into the meridian, representative of those with larger and smaller proximal periapsides. Spacecraft motion is from north to south. Small solid circles just north of the equator indicate the field parallel points where the trajectories in the meridian lie tangent to the field lines, corresponding to the points where they attain maximum mapped colatitudes (minimum mapped latitudes) in the ionosphere, while small open circles located south of the equator indicate the periapsis points. Figure b shows the region containing the D ring field lines in the same format but on an expanded scale. Arrowed green lines show the intra‐D ring current system envisaged, consisting of a variable meridional ionospheric current, Im, positive northward as shown, closed by an outer field‐aligned current, j‖, positive southward along the background field as shown, resulting in an interior positive azimuthal perturbation field Bφ. The blue and red lines show cuts in the meridian through surfaces of revolution about the z axis that are employed in section in the application of Ampère's circuital law to the observation of azimuthal field Bφ at the arbitrary intra‐D ring point shown by the solid black circle. The solid portions of these lines follow field lines from the observation point to the conducting layer of the ionosphere, while the dashed portions complete the surface in some arbitrary manner through the body of the planet.
  • License:
  • Rights Managed
  • Rights Holder:
  • John Wiley & Sons, Inc.
  • License Rights Holder:
  • ©2019. American Geophysical Union. All Rights Reserved.
  • Asset Type:
  • Image
  • Asset Subtype:
  • Image Orientation:
  • Landscape
  • Image Dimensions:
  • 2128 x 1224
  • Image File Size:
  • 7.47 MB
  • Creator:
  • G.J. Hunt, S.W.H. Cowley, G. Provan, H. Cao, E.J. Bunce, M.K. Dougherty, D.J. Southwood
  • Credit:
  • Hunt, G. J., Cowley, S. W. H., Provan, G., Cao, H., Bunce, E. J., Dougherty, M. K., & Southwood, D. J. (2019). Currents Associated With Saturn's Intra‐D Ring Azimuthal Field Perturbations. Journal of Geophysical Research: Space Physics, 124(7), 5675-5691. https://doi.org/10.1029/2019JA026588.
  • Collection:
  • Keywords:
  • Restrictions:
  • Property Release:
  • No
  • Model Release:
  • No
  • Purchasable:
  • Yes
  • Sensitive Materials:
  • No
  • Article Authors:
  • G.J. Hunt, S.W.H. Cowley, G. Provan, H. Cao, E.J. Bunce, M.K. Dougherty, D.J. Southwood
  • Article Copyright Year:
  • 2019
  • Publication Volume:
  • 124
  • Publication Issue:
  • 7
  • Publication Date:
  • 07/01/2019
  • DOI:
  • https://doi.org/10.1029/2019JA026588

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