摘要
The continuous wavelet transform (CWT) analysis reveals the instantaneous variability of the foraminiferal δ 18O and δ 13C of Site 1143 for the past 5 Ma at the eccentricity, obliquity and precession bands. The cross CWT analysis further demonstrates nonstationary phases of the benthic -δ 18O relative to ETP at the three primary Milankovitch bands in the last 5 Ma. The instantaneous phases between benthic -δ 18O and δ 13C at the precession band display a prominent 128 ka period, probably the cyclicity of the nonstationary climate close to the eccentricity. To explain these nonstationary phases, it is desirable to introduce a nonlinear response model to the global climate system, in which the output has a prominent cycle around 100 ka to match the 128 ka cycle of the instantaneous phase of the δ 13C and -δ 18O on the precession band.
The continuous wavelet transform (CWT) analysis reveals the instantaneous variability of the foraminiferal δ 18O and δ 13C of Site 1143 for the past 5 Ma at the eccentricity, obliquity and precession bands. The cross CWT analysis further demonstrates nonstationary phases of the benthic -δ 18O relative to ETP at the three primary Milankovitch bands in the last 5 Ma. The instantaneous phases between benthic -δ 18O and δ 13C at the precession band display a prominent 128 ka period, probably the cyclicity of the nonstationary climate close to the eccentricity. To explain these nonstationary phases, it is desirable to introduce a nonlinear response model to the global climate system, in which the output has a prominent cycle around 100 ka to match the 128 ka cycle of the instantaneous phase of the δ 13C and -δ 18O on the precession band.
基金
ThispaperissupportedbytheNationalNaturalScienceFoundationofChina(Nos. 40 30 60 1 1 ,4999560and 40 32 1 60 3 )andtheNKBRSF (No .G2 0 0 0 0 7850 0 )
