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Solar wind control of auroral zone geomagnetic activity
Author(s) -
Clauer C. Robert,
McPherron Robert L.,
Searls Craig,
Kivelson Margaret G.
Publication year - 1981
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/gl008i008p00915
Subject(s) - solar wind , substorm , earth's magnetic field , geophysics , magnetopause , magnetosphere , physics , meteorology , atmospheric sciences , environmental science , magnetic field , quantum mechanics
An empirical analysis of solar wind‐magnetosphere energy coupling functions is reported. Using the technique of linear prediction filtering with 2.5 minute data, we examine the relationship of auroral zone geomagnetic activity to solar wind power input functions which depend on the solar wind quantities VB², VB s , or V²B s . In this analysis a least squares prediction filter or impulse response function which relates a solar wind power function to an auroral zone geomagnetic index is designed directly from the data. We find that the computed impulse response functions have the characteristics of a low pass filter with a time delay which may be dependent on the strength of the energy input. While the AL index is reasonably well related to the solar wind energy functions, the AU index shows a substantially poorer relationship. In addition, high frequency variations of the auroral indices and some substorm expansions are not predictable with solar wind information alone, suggesting that internal magnetospheric processes partially control the AL index. We also find that the ϵ parameter which depends on VB² in the solar wind has a poorer relationship to auroral zone geomagnetic activity than a power parameter having a VB s solar wind dependence.