DOI: 10.1007/s00382-016-3304-3
Scopus记录号: 2-s2.0-84982918784
论文题名: Understanding positive feedback between PNA and synoptic eddies by eddy structure decomposition method
作者: Zhou F. ; Ren H.-L. ; Xu X.-F. ; Zhou Y.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2017
卷: 48, 期: 2017-11-12 起始页码: 3813
结束页码: 3827
语种: 英语
英文关键词: Downstream feedback
; Eddy structure decomposition
; Meridional eddy fluxes
; Pacific–North American (PNA) pattern
; Positive eddy feedback
; Zonal eddy fluxes
英文摘要: In the upper troposphere during winter, positive synoptic eddy (SE) feedback plays an indispensible role in maintaining the Pacific–North American (PNA) pattern that dominates climate variability on inter-annual timescales over the North Pacific and downstream regions. This study shows that the eddy forcing, induced by eddy-vorticity (EV) fluxes, is not only in-phase with, but also downstream to the PNA pattern in terms of its northeast Pacific lobe. We employ the eddy structure decomposition method to understand such an observed PNA-SEs feedback, and propose a kinematic mechanism that can depict dynamical processes associated with the eddy structure change and its induced positive eddy feedback relative to the PNA flow pattern. With this method, the winter-mean PNA-related SE structures are separated into climatological (basic) and anomalous SE structures, and these two parts can be used to represent the changes in SE structure in a statistical sense and then to calculate the EV fluxes in order to further elucidate the feedback mechanism. It is demonstrated that, on one hand, the winter-mean PNA flow tends to systematically deform the structures of SEs and induce anomalous EV fluxes, and these winter-mean EV fluxes primarily converge into the PNA cyclonic center, which, in return enhances the PNA flow. On the other hand, the PNA-related northeast Pacific flow is featured by a stronger zonal wind shear in the east than the west, which can induce larger zonal-slanting eddy structure change and then stronger meridional EV fluxes that converge to form downstream feedback. This kinematic mechanism may help to deeply understand the dynamical eddy feedback between the low-frequency PNA flow and high-frequency SEs. © 2016, The Author(s). 资助项目: NSF, National Science Foundation
Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/53208
Appears in Collections: 过去全球变化的重建
There are no files associated with this item.
作者单位: Nanjing University of Information Science and Technology, Nanjing, China; Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, 46 Zhongguancun Nandajie St., Haidian District, Beijing, China; Joint Center for Global Change Studies, Beijing, China
Recommended Citation:
Zhou F.,Ren H.-L.,Xu X.-F.,et al. Understanding positive feedback between PNA and synoptic eddies by eddy structure decomposition method[J]. Climate Dynamics,2017-01-01,48(2017-11-12)