DOI: 10.1007/s00382-013-1949-8
Scopus记录号: 2-s2.0-84906739413
论文题名: An introduction to combined Fourier-wavelet transform and its application to convectively coupled equatorial waves
作者: Kikuchi K.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2014
卷: 43, 期: 2017-05-06 起始页码: 1339
结束页码: 1356
语种: 英语
英文关键词: Annual cycle
; Convectively coupled equatorial waves
; Interannual variability
; Tropical convection
; Wavelet
英文摘要: Convectively coupled equatorial waves (CCEWs) are major sources of tropical day-to-day variability. The majority of CCEWs-related studies for the past decade or so have based their analyses, in one form or another, on the Fourier-based space-time spectral analysis method developed by Wheeler and Kiladis (WK). Like other atmospheric and oceanic phenomena, however, CCEWs exhibit pronounced nonstationarity, which the conventional Fourier-based method has difficulty elucidating. The purpose of this study is to introduce an analysis method that is able to describe the time-varying spectral features of CCEWs. The method is based on a transform, referred to as the combined Fourier-wavelet transform (CFWT), defined as a combination of the Fourier transform in space (longitude) and wavelet transform in time, providing an instantaneous space-time spectrum at any given time. The elaboration made on how to display the CFWT spectrum in a manner analogous to the conventional method (i.e., as a function of zonal wavenumber and frequency) and how to estimate the background noise spectrum renders the method more practically feasible. As a practical example, this study analyzes 3-hourly cloud archive user service (CLAUS) cloudiness data for 23 years. The CFWT and WK methods exhibit a remarkable level of agreement in the distributions of climatological-mean space-time spectra over a wide range of space-time scales ranging in time from several hours to several tens of days, indicating the instantaneous CFWT spectrum provides a reasonable snapshot. The usefulness of the capability to localize space-time spectra in time is demonstrated through examinations of the annual cycle, interannual variability, and a case study. © 2013 Springer-Verlag Berlin Heidelberg. 资助项目: NSF, National Science Foundation
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/54538
Appears in Collections: 过去全球变化的重建
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作者单位: International Pacific Research Center, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, 1680 East West Road, POST Bldg. 401, Honolulu, HI, 96822, United States
Recommended Citation:
Kikuchi K.. An introduction to combined Fourier-wavelet transform and its application to convectively coupled equatorial waves[J]. Climate Dynamics,2014-01-01,43(2017-05-06)