Open AccessA statistical look at plasmaspheric drainage plumes
Author(s) -
Borovsky Joseph E.,
Denton Michael H.
Publication year - 2008
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007ja012994
Subject(s) - plume , plasmasphere , storm , panache , atmospheric sciences , geology , geomagnetic storm , environmental science , plasma , meteorology , magnetosphere , physics , solar wind , oceanography , quantum mechanics
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 × 10 26 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 × 10 31 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.