Adaptive filtering and maximum entropy spectra with application to changes in atmospheric angular momentum
Article first published online: 21 SEP 2012
Copyright 1991 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 96, Issue D12, pages 22659–22671, 20 December 1991
How to Cite
1991), Adaptive filtering and maximum entropy spectra with application to changes in atmospheric angular momentum, J. Geophys. Res., 96(D12), 22659–22671, doi:10.1029/91JD02107., , and (
- Issue published online: 21 SEP 2012
- Article first published online: 21 SEP 2012
- Manuscript Accepted: 19 JUN 1991
- Manuscript Received: 13 NOV 1990
The spectral resolution and statistical significance of a harmonic analysis obtained by low-order maximum entropy methods (MEM) can be improved by subjecting the data to an adaptive filter. This adaptive filter consists of projecting the data onto the leading temporal empirical orthogonal functions obtained from singular spectrum analysis (SSA). The combined SSA-MEM method is applied both to a synthetic time series and a time series of atmospheric angular momentum (AAM) data. The procedure is very effective when the background noise is white and less so when the background noise is red. The latter case obtains in the AAM data. Nevertheless, we detect reliable evidence for intraseasonal and interannual oscillations in AAM. The interannual periods include a quasi-biennial one and a low-frequency one, of 5 years, both related to the El Niño/Southern Oscillation. In the intraseasonal band, separate oscillations of about 48.5 and 51 days are ascertained.