Accession Number : ADP001445

Title :   Theoretical MHD (Magnetohydrodynamic) Simulations of Coronal Transients and Interplanetary Observations,

Corporate Author : NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION BOULDER CO ENVIRONMENTAL RESEARCH LABS

Personal Author(s) : Dryer,M. ; Steinolfson,R. S. ; Smith,Z. K.

Report Date : 27 DEC 1982

Pagination or Media Count : 15

Abstract : A major long-range goal of theoretical simulations of solar-generated disturbances (transients, coronal holes, etc.) is the realistic modeling of a propagating disturbance from the sun into and throughout interplanetary space. Simulations of this kind, using MHD fluid theory, must always be confronted with observations in order to assess the degree to which one or the other is inadequate. We describe some of this on-going work which is concerned with both one- and two-dimensional, time-dependent MHD simulations. The first example simulates a flare-produced coronal transient. In this case, a sudden current pulse is assumed to produce emerging magnetic flux. This 'magnetic pulse' is sufficient to drive a weak shock wave into the solar wind by virtue of an outwardly-directed Lorentz force. The pulse is assumed to consist of a linearly-increasing (with time) magnetic field of 0.72 G at the base of a closed magnetic topology (initially in hydrostatic equilibrium) to a value ten times larger over a 10-minute period. The shock achieves a velocity of 230 km/s (which would be superimposed upon the existing solar wind). A second example deals with a series of corotating interaction regions observed during a 60-day period by Pioneers 10 and 11 in 1973 prior to, during, and subsequent to the former spacecraft's flyby of Jupiter. An opportunity for a stringent test of our one-dimensional model was made possible by the nearly radial alignment of these two spacecraft.

Descriptors :   *Solar disturbances, *Electromagnetic wave propagation, *Magnetohydrodynamics, Interplanetary space, Transients, Simulation, One dimensional, Two dimensional, Time dependence, Solar wind, Solar corona, Motion, Magnetic fields, Flux(Rate), Pulses, Theory

Distribution Statement : APPROVED FOR PUBLIC RELEASE