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A statistical look at plasmaspheric drainage plumes

Research output: Contribution to journalJournal article

Published

Journal publication date09/2008
JournalJournal of Geophysical Research
Journal numberA09221
Volume113
Number of pages23
Pages1-23
Original languageEnglish

Abstract

The properties of plasmaspheric drainage plumes are examined using cold-plasma measurements in geosynchronous orbit. During high-speed stream-driven storms, 210 plume crossings are collected and statistically analyzed. Plumes that persist for 4 days are common, which was the duration of our search. Plumes weaken with age, becoming narrower in local time with plasma that becomes less dense. Cold-plasma flow velocities are sunward in the plumes, with flow speeds decreasing as the storms progress. Plumes transfer typically 2 × 1026 ions/sec (1.2 ton/hr of protons) when they are young, and the rate of transport decreases with plume age. A total of approximately 2 × 1031 ions (34 tons of protons) are transported via plumes in the life of a storm. About half of the outer plasmasphere is drained in the first 20 hours of a storm. Large density fluctuations in the plumes indicate that the drainage plumes are lumpy, and large velocity fluctuations of the plasma flow indicate that the drainage plumes may be turbulent. Because of their persistence, drainage plumes are anticipated to be a regular feature of any ongoing geomagnetic storm.

Bibliographic note

Copyright (2008) American Geophysical Union. Further reproduction or electronic distribution is not permitted