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Relation of Pc 1 micropulsations to the ring current and geomagnetic storms

1972; American Geophysical Union; Volume: 77; Issue: 34 Linguagem: Inglês

10.1029/ja077i034p06746

2156-2202

R. R. Heacock, M. Kivinen,

Astro and Planetary Science

The Pc 1 micropulsations were recorded at College, Alaska, Thule, Greenland, and at Sodankyla and Nurmijarvi, Finland, from November 1967 through January 1970. Cross-correlation analysis disclosed a significant tendency for periodically structured Pc 1 to occur during ring current recoveries. Semistructured and unstructured Pc 1 and 2 activity tends to occur in the initial phase and in the early part of the growing phase of magnetic storms. Source lines for structured Pc 1 events are principally on the dayside. These results are related to theoretical results of Kennel and Petschek, Cornwall and associates, and Brice and Lucas; i.e., the plasmasphere fills during the storm recovery phase, preferentially on the dayside, and the intersection of the ring current with the increasing cold-plasma density of the plasmasphere results in the cyclotron instability when the stable trapping limit is reached.