Tearing modes at the magnetopause
Abstract
This paper examines the possible occurrence of tearing modes in the dayside magnetopause. First, the expected magnetic signature of tearing, as obtained from existing theory, is reviewed. Magnetometer data from one terrestrial magnetopause crossing of Jupiter's magnetopause are then examined in detail. Magnetic field oscillations are found in three subsegments of the terrestrial crossing at a frequency of 0.1-0.2 Hz and with peak amplitudes of 5-10 nanotesla (nT), and in one segment of the Jovian crossing, at 0.05-0.1 Hz and with 2-nT amplitude. The frequency range, as well as the orientation of the magnetic field perturbation vectors, agrees with a model in which tearing-produced magnetic islands are convected past the satellite with the plasma flow in the current layer. In both cases the magnetopause structure was of the rotational discontinuity type with a nonvanishing normal magnetic field component. Hence, if the tearing structures were active, i.e., growing, at the observation site, ion tearing (or perhaps resistive tearing, with the resistivity provided by microturbulence) must be invoked. But it is also possible that the structures were passive, consisting of 'debris' from active tearing elsewhere on the magnetopause surface, this debris being convected along the magnetopause past the observation site.
- Publication:
-
Journal of Geophysical Research
- Pub Date:
- March 1981
- DOI:
- 10.1029/JA086iA03p01305
- Bibcode:
- 1981JGR....86.1305G
- Keywords:
-
- Earth Atmosphere;
- Jupiter Atmosphere;
- Magnetopause;
- Plasma Layers;
- Tearing Modes (Plasmas);
- Daytime;
- Ogo-5;
- Pioneer 11 Space Probe;
- Plasma Currents;
- Power Spectra