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Full-Text Articles in Physical Sciences and Mathematics
Rectification Of The Bias In The Wavelet Power Spectrum, Yonggang Liu, X. San Liang, Robert H. Weisberg
Rectification Of The Bias In The Wavelet Power Spectrum, Yonggang Liu, X. San Liang, Robert H. Weisberg
Yonggang Liu
This paper addresses a bias problem in the estimate of wavelet power spectra for atmospheric and oceanic datasets. For a time series comprised of sine waves with the same amplitude at different frequencies the conventionally adopted wavelet method does not produce a spectrum with identical peaks, in contrast to a Fourier analysis. The wavelet power spectrum in this definition, that is, the transform coefficient squared (to within a constant factor), is equivalent to the integration of energy (in physical space) over the influence period (time scale) the series spans. Thus, a physically consistent definition of energy for the wavelet power …
Current Patterns On The West Florida Shelf From Joint Self-Organizing Map Analyses Of Hf Radar And Adcp Data, Yonggang Liu, Robert H. Weisberg, Lynn K. Shay
Current Patterns On The West Florida Shelf From Joint Self-Organizing Map Analyses Of Hf Radar And Adcp Data, Yonggang Liu, Robert H. Weisberg, Lynn K. Shay
Yonggang Liu
To assess the spatial structures and temporal evolutions of distinct physical processes on the West Florida Shelf, patterns of ocean current variability are extracted from a joint HF radar and ADCP dataset acquired from August to September 2003 using Self-Organizing Map (SOM) analyses. Three separate ocean– atmosphere frequency bands are considered: semidiurnal, diurnal, and subtidal. The currents in the semidiurnal band are relatively homogeneous in space, barotropic, clockwise polarized, and have a neap-spring modulation consistent with semidiurnal tides. The currents in the diurnal band are less homogeneous, more baroclinic, and clockwise polarized, consistent with a combination of diurnal tides and …