The roles of atmospheric stochastic forcing (SF) and oceanic entrainment temperature (T-e) in decadal modulation of ENSO

IOCAS-IR > 海洋环流与波动重点实验室

	The roles of atmospheric stochastic forcing (SF) and oceanic entrainment temperature (T-e) in decadal modulation of ENSO
	Zhang Ronghua; Busalacchi Antonio J.
	2008-02
发表期刊	JOURNAL OF CLIMATE
卷号	21 期号:4 页码:674-704
摘要	The El Nino-Southern Oscillation (ENSO) has been observed to exhibit decadal changes in its properties; the cause and implication of such changes are strongly debated. Here the authors examine the influences of two particular attributors of the ocean-atmospheric system. The roles of stochastic forcing (SF) in the atmosphere and decadal changes in the temperature of subsurface water entrained into the mixed layer (T-e) in modulating ENSO are compared to one another using coupled ocean-atmosphere models of the tropical Pacific climate system. Two types of coupled models are used. One is an intermediate coupled model (ICM) and another is a hybrid coupled model (HCM), both of which consist of the same intermediate ocean model (IOM) with an empirical parameterization for T-e, constructed via singular value decomposition (SVD) analysis of the IOM simulated historical data. The differences in the ICM and HCM are in the atmospheric component: the one in the ICM is an empirical feedback model for wind stress (tau), and that in the HCM is an atmospheric general circulation model (AGCM; ECHAM4.5). The deterministic component of atmospheric tau variability, representing its signal response (tau(Sig)) to an external SST forcing, is constructed statistically by an SVD analysis from a 24-member ensemble mean of the ECHAM4.5 AGCM simulations forced by observed SST; the SF component (tau(SF)) is explicitly estimated from the ECHAM4.5 AGCM ensemble and HCM simulations. Different SF representations are specified in the atmosphere: the SF effect can be either absent or present explicitly in the ICM, or implicitly in the HCM where the ECHAM4.5 AGCM is used as a source for SF. Decadal changes in the ocean thermal structure observed in the late 1970s are incorporated into the coupled systems through the Te parameterizations for the two subperiods before (1963-79) and after (1980-96) the climate shift (T-e(63-79) and T-e(80-96)), respectively. The ICM and HCM simulations well reproduce interannual variability associated with El Nino in the tropical Pacific. Model sensitivity experiments are performed using these two types of coupled models with different realizations of SF in the atmosphere and specifications of decadal T-e changes in the ocean. It is demonstrated that the properties of ENSO are modulated differently by these two factors. The decadal T-e changes in the ocean can be responsible for a systematic shift in the phase propagation of ENSO, while the SF in the atmosphere can contribute to the amplitude and period modulation in a random way. The relevance to the observed decadal ENSO variability in the late 1970s is discussed.
关键词	Sea-surface Temperature Nino-southern-oscillation Hybrid Coupled Model General-circulation Model Sst Anomaly Simulations Tropical Pacific-ocean Interannual Variability Climate Models Interdecadal Change Equatorial Pacific
收录类别	SCI
语种	英语
文献类型	期刊论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/18167
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	Zhang Ronghua,Busalacchi Antonio J.. The roles of atmospheric stochastic forcing (SF) and oceanic entrainment temperature (T-e) in decadal modulation of ENSO[J]. JOURNAL OF CLIMATE,2008,21(4):674-704.
APA	Zhang Ronghua,&Busalacchi Antonio J..(2008).The roles of atmospheric stochastic forcing (SF) and oceanic entrainment temperature (T-e) in decadal modulation of ENSO.JOURNAL OF CLIMATE,21(4),674-704.
MLA	Zhang Ronghua,et al."The roles of atmospheric stochastic forcing (SF) and oceanic entrainment temperature (T-e) in decadal modulation of ENSO".JOURNAL OF CLIMATE 21.4(2008):674-704.

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