Mapping the open/closed boundary in Jupiter’s polar cap with a 2-D equatorial magnetic field model

Details Mapping the open/closed boundary in Jupiter’s polar cap with a 2-D equatorial magnetic field model Mapping the open/closed boundary in Jupiter’s polar cap with a 2-D equatorial magnetic field model

Dec 2009

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufmsm23b1616v&link_type=abstract

American Geophysical Union, Fall Meeting 2009, abstract #SM23B-1616

Physics

[2704] Magnetospheric Physics / Auroral Phenomena, [2756] Magnetospheric Physics / Planetary Magnetospheres, [5706] Planetary Sciences: Fluid Planets / Aurorae, [5737] Planetary Sciences: Fluid Planets / Magnetospheres

Scientific paper

The main auroral oval emissions at Jupiter are not associated with the open/closed flux boundary in the polar cap as they are at the Earth, but with the breakdown of plasma corotation in the middle magnetosphere. As a result, the boundary between open and closed flux in the ionosphere is not well defined, though the region of open flux is generally thought to be small. We have mapped contours of constant radial distance from the magnetic equator to the ionosphere with the objective of understanding how auroral features relate to magnetospheric sources. Instead of following along a model field, we map equatorial field lines to the ionosphere by requiring that the magnetic flux in some specified region at the equator equal the magnetic flux in the area to which it maps in the ionosphere. We represent the north-south component of the measured magnetic field (Bθ) at the equator as a function of radial distance and local time by fitting equatorial field measurements to a two-dimensional functional form. From the equatorial field function, we calculate the flux through the equator in pixels of radial increment 5 RJ and a fixed longitudinal. We start by identifying the ionospheric footprint of an equatorial curve at 20 RJ where field models are reasonably accurate. The pixels at 20 RJ are traced to the ionosphere using the field bend back from Khurana and Schwarzl (2005) to determine the corresponding surface longitude. Using a version of the VIP4 model (Connerney et al., 1998) that has been modified to include the effects of the current sheet (Khurana, 1997) to estimate the internal Jovian field in the ionosphere, we then displace the auroral boundary poleward until the ionospheric flux equals the flux in the equatorial pixel. With iteration, we obtain the ionospheric mapping of the 25 RJ circle at the equator. Further iteration provides the mapping of successively distant circles. Equating the fluxes in this way allows us to link a given position in the magnetosphere to a position in the ionosphere and to gain insight into the source of different auroral features. In particular, the approach allows us to identify the mapping of the dayside magnetopause and thereby establish possible locations of a portion of the open/closed flux boundary in Jupiter’s polar cap. The results should be useful in understanding models of dynamics and the open or closed nature of the Jovian magnetosphere.

Affiliated with

Also associated with

No associations

Rating

Mapping the open/closed boundary in Jupiter’s polar cap with a 2-D equatorial magnetic field model does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Mapping the open/closed boundary in Jupiter’s polar cap with a 2-D equatorial magnetic field model, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mapping the open/closed boundary in Jupiter’s polar cap with a 2-D equatorial magnetic field model will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1878014