NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
On the embedding-dimension analysis of AE and AL time seriesSeveral authors have employed the embedding-dimension method to analyze time series of geomagnetic indices, with differing results for the value of the correlation dimension nu. It is argued that these differences may arise from corresponding differences in the length and construction of the various data sets used. Practical application of the method to sets of discretized data requires use of a delay time scale set by the autocorrelation time of the data set. It is found that a particular data set containing 35 days of AE exhibits an autocorrelation time tau(c) longer by an order of magnitude than that of a short-duration (less than 5 days) set, raising the possibility that extant analyses of long-duration sets may have employed delay times shorter than tau(c). In addition, the power spectrum of AE reveals modulation at a period of 24 hr. A numerical experiment on the logistic map shows that such modulation introduces an extra degree of freedom in the data, resulting in an augmented correlation dimension.
Document ID
19910063757
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Shan, Lin-Hua
(Iowa Univ. Iowa City, IA, United States)
Goertz, Christoph
(Iowa Univ. Iowa City, IA, United States)
Smith, Robert A.
(Iowa, University Iowa City, United States)
Date Acquired
August 14, 2013
Publication Date
August 1, 1991
Publication Information
Publication: Geophysical Research Letters
Volume: 18
ISSN: 0094-8276
Subject Category
Geophysics
Accession Number
91A48380
Funding Number(s)
CONTRACT_GRANT: NAGW-970
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available