HR: 1300h
AN: SM52A-0561    [PDF]
TI: A Statistical Study of the Global Structure of the Ring Current
AU: * Jorgensen, A M
EM: ajorg@lanl.gov
AF: Los Alamos National Laboratory, NIS-4, MS D448, Los Alamos, NM 87545 United States
AU: Singer, H J
EM: howard.singer@noaa.gov
AF: NOAA space environment center, 325 Broadway, Boulder, CO 80305 United States
AU: Hughes, W J
EM: hughes@bu.edu
AF: Boston University, Center for Space Physics, 725 Commonwealth Avenue, Boston, MA 02215 United States
AU: Spence, H E
EM: spence@bu.edu
AF: Boston University, Department of Astronomy, 725 Commonwealth Avenue, Boston, MA 02215 United States
AB: In this paper we derive the average configuration of the ring current as a function of the state of the magnetosphere as indicated by the $Dst$ index. We sort magnetic field data from the Combined Release and Radiation Effects Satellite (CRRES) by spatial location and by the $Dst$ index in order to produce magnetic field maps. From these maps we calculate local current systems by taking the curl of the magnetic field. We find both the westward (outer) and the eastward (inner) components of the ring current. We find that the ring current intensity varies linearly with $Dst$ as expected, and that the ring current is asymmetric for all $Dst$ values. The azimuthal peak of the ring current is located in the afternoon sector for quiet conditions, and near midnight for disturbed conditions. The ring current also moves closer to the Earth during disturbed conditions. We attempt to recreate the $Dst$ index by integrating the magnetic perturbations caused by the ring current. We find that we need to multiply our computed disturbance by a factor of $1.88\pm0.27$ and add an offset of $3.84\pm4.33\,nT$ in order to get optimal agreement with $Dst$. When taking into account a tail current contribution of roughly 25% [Turner et al., 2002], this agree well with our expectation of a factor of $1.3$ to $1.5$ based on a partially conducting Earth. The offset does not agree well with an offset of approximately $20\,nT$ based on solar wind pressure.
UR: http://nis-www.lanl.gov/~ajorg/papers/crerc.pdf
DE: 2708 Current systems (2409)
DE: 2730 Magnetosphere--inner
DE: 2778 Ring current
DE: 2788 Storms and substorms
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting