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Persistence of the ring current, 1958–1984
Author(s) -
Wrenn Gordon L.
Publication year - 1989
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl016i008p00891
Subject(s) - ring current , magnetosphere , ionosphere , physics , solar minimum , atmospheric sciences , storm , solar maximum , solar cycle , persistence (discontinuity) , current (fluid) , meteorology , environmental science , computational physics , astrophysics , geophysics , solar wind , geology , plasma , nuclear physics , geotechnical engineering , thermodynamics
Statistical evidence for a solar cycle modulation in storm‐time ring current particle lifetimes is presented. Linear regression of Dst with respect to a p (τ), and an optimisation of τ to maximise correlation, gives characteristic persistence times for each year through 2.5 solar cycles. These average persistences vary between less than 10 h at solar minimum (1962, 1975) to greater than 16 h at solar maximum (1970, 1981). The analysis is biassed toward the later stages of recovery when the rate of decay has reduced, but the result is not a function of mean current strength or frequency of large storms. Increased abundance of O + is postulated as the most probable explanation of longer particle lifetimes at solar maximum, this strongly supports the proposition that a large fraction of the ring current is of ionospheric origin, and underlines the importance of dynamic coupling between the ionosphere and magnetosphere during disturbed periods.