A two-dimensional simulation of the radial and latitudinal evolution of a solar wind disturbance driven by a fast, high-pressure coronal mass ejection

Journal Article · Tue Jul 01 04:00:00 EDT 1997 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/97JA01131· OSTI ID:550419

Riley, P; Gosling, J T ^[1]; Pizzo, V J ^[2]

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1. Los Alamos National Laboratory, Los Alamos, New Mexico (United States)
2. Space Environment Laboratory, National Oceanic and Atmospheric Administration, Boulder, Colorado (United States)

Using a hydrodynamic simulation, we have studied the two-dimensional (symmetry in the azimuthal direction) evolution of a fast, high-pressure coronal mass ejection (CME) ejected into a solar wind with latitudinal variations similar to those observed by Ulysses. The latitudinal structure of the ambient solar wind in the meridional plane is approximated by two zones: At low latitudes ({lt}20{degree}) the solar wind is slow and dense, while at higher latitudes the solar wind is fast and tenuous. The CME is introduced into this ambient wind as a bell-shaped pressure pulse in time, spanning from the equator to 45{degree} with a speed and temperature equal to that of the high-latitude solar wind. Such an ejection profile produces radically different disturbance profiles at low and high latitudes. The low-latitude portion of the ejecta drives a highly asymmetric disturbance because of the relative difference in speed between the fast CME and slower ambient solar wind ahead. The high-latitude portion of the same ejecta material drives a much more radially symmetric disturbance because the relative difference in pressure between the CME and ambient background plasma dominates the dynamics. The simulations reveal other interesting features. There is significant distortion of the CME in the interplanetary medium. By {approximately}1AU the CME has effectively separated (in radius as well as latitude) into two pieces. The radial separation is due to the strong velocity shear between the slow and fast ambient solar wind. The latitudinal separation arises from pressure gradients associated with rarefaction regions that develop as the CME propagates outward. There is significant poleward motion of the highest-latitude portion of the CME and its associated disturbance. The main body of the CME expands poleward by {approximately}18{degree}, while the forward and reverse waves (produced by the overexpanding portion of the CME) propagate all the way to the pole. (Abstract Truncated)

• OSTI ID: 550419
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A7 Vol. 102; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
INTERPLANETARY SPACE
PLASMA PRESSURE
PLASMA SIMULATION
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR CORONA
SOLAR FLARES
SOLAR WIND