摘要： We extend the spherical harmonic stacking (SHS) method of Buland et al. (1979) for the radial (vertical) component in the seismogram to the transverse (horizontal) components of the displacement field. Taking advantage of the orthogonality of the spherical harmonic functions (scalar and vectorial), SHS isolates and accentuates the signals of individual singlets of the Earth's normal modes of free oscillation. We apply the SHS on the broadband Incorporated Research Institutions for Seismology (IRIS) seismograms from up to 97 IRIS seismic stations for the 2004 Sumatra‐Andaman earthquake, in experiments targeted to spheroidal as well as toroidal modes—2S1, 0S3, 2S2, 3S1, 1S3, 0T2, and 0T3. We report the complete resolution of the singlet frequencies of these multiplets, some for the first time, and estimate the singlets' complex frequencies using the frequency domain autoregressive method of Chao and Gilbert (1980). The latter contain useful information to be used in inversions for the 3‐D structure of the Earth's interior. Key Points A new spherical harmonic stacking method to resolve normal mode singlets We demonstrate the successful application of SHS in real experiments Complete resolution of singlets of interest and new findings are reported 其他題名： Geophys. Res. Lett 出版者： Washington: Blackwell Publishing Ltd 出版日期： 2014-08-16 出處： Geophysical research letters, 2014-08, Vol.41 (15), p.5428-5435 資源來源： Wiley Journals 版權： 2014. American Geophysical Union. All Rights Reserved. 識別號： ISSN: 0094-8276 識別號： ISSN: 1944-8007 識別號： EISSN: 1944-8007 識別號： DOI: 10.1002/2014GL060700
