ICS-13 Abstract View

 

The Nonlinear Dynamics of Substorms with the WINDMI Model
Spencer, E.A., espencer@southalabama.edu (1)
Srinivas, P.K., ps1621@jagmail.southalabama.edu (1)
Vadepu, S.K., sv1522@jagmail.southalabama.edu (1)
Crabtree, C., chris.crabtree@nrl.navy.mil (2)
Horton, W., wendell.horton@gmail.com (3)
We discuss a low order physics model of the nightside magnetosphere called WINDMI. The model uses solar wind and IMF measurements from the ACE spacecraft as input into a system of 8 nonlinear ordinary differential equations. The state variables of the differential equations represent the energy stored in the geomagnetic tail, central plasma sheet, ring current and field aligned currents. The output from the model is the geomagnetic westward auroral electrojet (AL) index, and the Dst index. We will show how the model has been used to analyze the dynamics of substorms.

Three classes of magnetospheric substorms are studied with the model, isolated substorms, storm time substorms, and periodic substorms. We analyze the model predictions to obtain the statistical average of the energy content in the earth's ring current, central plasma sheet and magnetotail prior to substorm onset. We use these statistical averages and their time rate of change to evaluate the possibility of several different instability mechanisms being the driver of substorm onset.
(1) Electrical and Computer Engineering Dept., Univ. of South Alabama
(2) US Naval Research Laboratory
(3) Dept. of Geophysics, Applied Research Laboratories, The University of Texas at Austin, TX, USA