Birkeland Currents and Ring Currents in the Computer Simulation of the Substorm of 19 September 1976,
RICE UNIV HOUSTON TEX DEPT OF SPACE PHYSICS AND ASTRONOMY
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Several computer runs simulating the behavior of the inner magnetosphere during a substorm-type event that occurred on 19 September 1976, have been completed and analyzed. The computer model simulates many aspects of the behavior of the closed-field-line portion of the earths magnetosphere, and the auroral and subauroral ionosphere. For these regions, the program self-consistently computes electric fields, electric currents, hot-plasma densities, plasma velocities and other parameters. Presented here are some highlights of the results of the event simulation. Predicted electric fields for several times during the event agree reasonably well with corresponding data from satellite S3-2. Detailed discussion is presented for a case of rapid subauroral flow that was observed on one S3-2 pass and is predicted by computer runs. The computed global distribution of Birkeland current agrees reasonably well with the observations of IIjima and Potemra. In the simulated substorm-type event, plasma-sheet ions are injected earthward of synchronous orbit near midnight and drift westward, forming a ring half-way around the earth by the end of the simulation, 3 hours after substorm onset. The dispersion of ion energies on the dusk side near synchronous orbit has the form commonly observed by McIlwain and collaborators. It appears that the ions would form a complete ring if the simulation were continued for several more hours.
- Atmospheric Physics