Paper#: 58
Poster #:
Session Name: Workshop 2A: Particle/MHD Substorms
Room: 200ABC
Day: Monday
Time: 11:20-11:40 a.m.
Abstract Title: Statistical Assessment of the Magnetotail Current Contribution to Dst
PresentSurname: Maltsev, Y.P.
All Authors: Y.P. Maltsev, A. A. Ostapenko
Abstract : To estimate the magnetotail current contribution to Dst we used the database of Fairfield et al. [JGR, 1994, V.99, 11319] which includes several tens thousand magnetic field observations for 20 years. Our attention was focused on the plane x = 0 separating the dayside and nightside magnetosphere. The symmetrical ring current yields zero normal component in this plane. Nonetheless, as shown by Ostapenko and Maltsev [JGR, 2000, V.105, 311] the database reveals a severe normal component Bx(x=0,y,z,Dst) which is evidently produced by the magnetotail and magnetopause currents. In order to estimate their ground effect we solved the Neumann boundary problem in the dayside magnetosphere. Since magnetic field of the magnetotail and magnetopause currents is curl-free here, the scalar magnetic potential satisfies the Laplace equation. As the boundary conditions we took the observed distribution of the normal magnetic field component. At the magnetopause the normal component was considered to be zero. At the x = 0 plane we took Bx(x=0,y,z,Dst) from the database of Fairfield et al. [1994]. The effect of the magnetopause current can be excluded with the use of the Mead [1964] model. The calculations show that the tail current provides more than 80% contribution to Dst.