气候变化领域集成服务门户(CCPortal): Nonlinear optimal moisture perturbations as excitation of primary MJO events in a hybrid coupled climate model

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DOI	10.1007/s00382-019-05021-7
	Nonlinear optimal moisture perturbations as excitation of primary MJO events in a hybrid coupled climate model
	Wei Y.; Ren H.-L.; Mu M.; Fu J.-X.
发表日期	2020
ISSN	0930-7575
起始页码	675
结束页码	699
卷号	54 期号:2020-01-02
英文摘要	Although the moisture feedback has been well known to be essential in the Madden–Julian Oscillation (MJO) dynamics, whether its pre-moistening effect plays a key role in exciting the onset of primary MJO events, as has been confirmed in the successive initiation, remains elusive. In this study, using a hybrid coupled climate model that has a good fidelity in simulating the intraseasonal variability, we develop a new framework of methodology to investigate the nonlinear excitation of primary MJO event, of which the key achievement is the successful implementation of the conditional nonlinear optimal perturbation (CNOP). In an application of this new framework, the CNOP-type moisture perturbations are calculated for the pre-chosen non-MJO reference states and generally favor a moistening in the equatorial region while drying in the poleward. Comparisons of the model simulation with observation give credibility to the existence of moisture signals several weeks before some primary MJO events. A suite of numerical experiments confirms that the CNOPs of moisture can contribute to the excitation and propagation of strong primary MJO events while random perturbations cannot. The moisture budget analysis further reveals the central importance of the horizontal moisture advection, especially the nonlinearly upscaled moisture transports associated with the high-frequency disturbances on the quasi-3–4-day and 6–8-day synoptic time scales, in supporting the nonlinear excitation of the primary MJO events. The subgrid-scale processes of evaporation, condensation and eddy transport of moisture are found to be critical for the pre-moistening effect in the boundary layer as well. This study directly supports the vital importance of the moisture perturbations, which are characterized by a particular pattern concentrated at low levels, to the nonlinear growth and propagation of the primary MJO events. © 2019, The Author(s).
英文关键词	CNOP; Nonlinear moisture advection; Nonlinear optimal excitation; Primary MJO event
语种	英语
scopus关键词	advection; atmospheric moisture; climate modeling; condensation; evaporation; Madden-Julian oscillation; moisture transfer; seasonal variation
来源期刊	Climate Dynamics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/145725
作者单位	Laboratory for Climate Studies and CMA-NJU Joint Laboratory for Climate Prediction Studies, National Climate Center, China Meteorological Administration, Beijing, 100081, China; Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Institute of Atmospheric Sciences and Department of Atmospheric and Oceanic Sciences, Fudan University, Shanghai, 200438, China
推荐引用方式 GB/T 7714	Wei Y.,Ren H.-L.,Mu M.,et al. Nonlinear optimal moisture perturbations as excitation of primary MJO events in a hybrid coupled climate model[J],2020,54(2020-01-02).
APA	Wei Y.,Ren H.-L.,Mu M.,&Fu J.-X..(2020).Nonlinear optimal moisture perturbations as excitation of primary MJO events in a hybrid coupled climate model.Climate Dynamics,54(2020-01-02).
MLA	Wei Y.,et al."Nonlinear optimal moisture perturbations as excitation of primary MJO events in a hybrid coupled climate model".Climate Dynamics 54.2020-01-02(2020).