caa a22 4500 475737784 CHVBK 20180406123451.0 cr unu---uuuuu 170329e20000301xx s 000 0 eng 10.1007/s001900050283 doi (NATIONALLICENCE)springer-10.1007/s001900050283 Improvement of edge effect of the wavelet time-frequency spectrum: application to the length-of-day series [Elektronische Daten] [D. Zheng, B. F. Chao, Y. Zhou, N. Yu] Abstract.:  The edge effect in the wavelet time-frequency spectrum of a time series is treated. The time series is first extended on both ends by applying a non-linear model, namely the leap-step time series analysis (LSTSA) model, prior to the wavelet transform. The results of a series of simulation experiments and an application to the observed length-of-day (LOD) series demonstrate that the edge effect is effectively reduced this way. Thus, the application of the LSTSA model improves the wavelet time-frequency spectrum, especially enhancing the ability to detect the low-frequency signals. Springer-Verlag Berlin Heidelberg, 2000 Key words: Wavelet transform - Edge effect - Length of day nationallicence Zheng D. Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PRC e-mail: zdw@center.shao.ac.cn; Tel.: +86 021 64386191; Fax: +86 021 64384618, CN aut Chao B. F. Space Geodesy Branch, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA, US aut Zhou Y. Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PRC e-mail: zdw@center.shao.ac.cn; Tel.: +86 021 64386191; Fax: +86 021 64384618, CN aut Yu N. Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PRC e-mail: zdw@center.shao.ac.cn; Tel.: +86 021 64386191; Fax: +86 021 64384618, CN aut https://doi.org/10.1007/s001900050283 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s001900050283 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Zheng D. Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PRC e-mail: zdw@center.shao.ac.cn; Tel.: +86 021 64386191; Fax: +86 021 64384618, CN aut NATIONALLICENCE 700 1- Chao B. F. Space Geodesy Branch, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA, US aut NATIONALLICENCE 700 1- Zhou Y. Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PRC e-mail: zdw@center.shao.ac.cn; Tel.: +86 021 64386191; Fax: +86 021 64384618, CN aut NATIONALLICENCE 700 1- Yu N. Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PRC e-mail: zdw@center.shao.ac.cn; Tel.: +86 021 64386191; Fax: +86 021 64384618, CN aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer