Actual Tropical Waves Identified by the Wavenumber-Frequency Spectrum Analysis during Boreal Summer
MAO Jiang-Yu1, WANG Zai-Zhi2
1LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 1000292National Climate Center, China Meteorological Administration, Beijing 100081
Actual Tropical Waves Identified by the Wavenumber-Frequency Spectrum Analysis during Boreal Summer
MAO Jiang-Yu1;WANG Zai-Zhi2
1LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 1000292National Climate Center, China Meteorological Administration, Beijing 100081
摘要Based on daily satellite-observed outgoing longwave radiation (OLR) data, the tropical intraseasonal oscillation (ISO) associated with the Asian summer monsoon is found to be dominant during the 2005 summer. Such an ISO along with other tropical waves are identified using a wavenumber-frequency spectrum analysis. Some of significant spectral peaks coincide well with the dispersion curves of the equatorially trapped wave modes from shallow water theory, with various equivalent depths of 12--200m, suggesting that actual tropical waves can be detected from observational data. Although the formation mechanism of the ISO is more complicated than those of other tropical waves with higher frequencies, significant spectral peaks that correspond to the ISO with a period of 30--60 days distinctly appear in the OLR spectra. The selective wavenumber-frequency filtering of OLR data is thus performed to isolate the ISO, Kelvin and equatorial Rossby waves, and the properties and signatures of such tropical waves that control tropical atmospheric variability for the 2005 summer are clearly identified.
Abstract：Based on daily satellite-observed outgoing longwave radiation (OLR) data, the tropical intraseasonal oscillation (ISO) associated with the Asian summer monsoon is found to be dominant during the 2005 summer. Such an ISO along with other tropical waves are identified using a wavenumber-frequency spectrum analysis. Some of significant spectral peaks coincide well with the dispersion curves of the equatorially trapped wave modes from shallow water theory, with various equivalent depths of 12--200m, suggesting that actual tropical waves can be detected from observational data. Although the formation mechanism of the ISO is more complicated than those of other tropical waves with higher frequencies, significant spectral peaks that correspond to the ISO with a period of 30--60 days distinctly appear in the OLR spectra. The selective wavenumber-frequency filtering of OLR data is thus performed to isolate the ISO, Kelvin and equatorial Rossby waves, and the properties and signatures of such tropical waves that control tropical atmospheric variability for the 2005 summer are clearly identified.
MAO Jiang-Yu;WANG Zai-Zhi. Actual Tropical Waves Identified by the Wavenumber-Frequency Spectrum Analysis during Boreal Summer[J]. 中国物理快报, 2008, 25(4): 1506-1509.
MAO Jiang-Yu, WANG Zai-Zhi. Actual Tropical Waves Identified by the Wavenumber-Frequency Spectrum Analysis during Boreal Summer. Chin. Phys. Lett., 2008, 25(4): 1506-1509.
[1] Chang C P 1970 J. Atmos. Sci. 27 113 [2] Takayabu Y N 1994 J. Meteor. Soc. Jpn. 72 433 [3] Matsuno T 1966 J. Meteor. Soc. Jpn. 44 433 [4] Gill A E 1982 Atmosphere--Ocean Dynamics (New York:Academic) p 662 [5] Wheeler M and Kiladis G N 1999 J. Atmos. Sci. 56 374 [6] Fu Z T et al %, Liu S D and Liu S K2004 Commun. Theor. Phys. 43 509 [7] Madden R A and Julian P R 1972 J. Atmos. Sci. 29 1109 [8] Jones C et al %, Carvalho L M V, Higgins R W, Waliser D and Schemm J K E2004 J. Climat. 17 523 [9] Wang B and Rui H 1990 Meteor. Atmos. Phys. 44 43 [10] Goswami B N and Mohan R S A 2001 J. Climat. 14 1180 [11] Zhang Y S et al %, Li T, Wang B and Wu G X2002 J. Climat. 153206 [12] Mao J Y and Chan J C L 2005 J. Climat. 18 2388 [13] Hayashi Y 1982 J. Meteor. Soc. Jpn. 60 156 [14] Hayashi Y and Golder D G 1997 J. Atmos. Sci. 54 1262 [15] Madden R A and Julian P R 1994 Mon. Wea. Rev. 122 814
2008, Vol. 25 
